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BY 4.0 license Open Access Published by De Gruyter July 7, 2023

Transsulfuration pathway: a targeting neuromodulator in Parkinson’s disease

  • Andrea Corona-Trejo , María E. Gonsebatt , Cristina Trejo-Solis , Victoria Campos-Peña , Laura Itzel Quintas-Granados , Edgar Yebrán Villegas-Vázquez , Octavio Daniel Reyes-Hernández , Vicente Jesús Hernández-Abad , Gabriela Figueroa-González ORCID logo EMAIL logo and Daniela Silva-Adaya EMAIL logo

Abstract

The transsulfuration pathway (TSP) is a metabolic pathway involving sulfur transfer from homocysteine to cysteine. Transsulfuration pathway leads to many sulfur metabolites, principally glutathione, H2S, taurine, and cysteine. Key enzymes of the TSP, such as cystathionine β-synthase and cystathionine γ-lyase, are essential regulators at multiple levels in this pathway. TSP metabolites are implicated in many physiological processes in the central nervous system and other tissues. TSP is important in controlling sulfur balance and optimal cellular functions such as glutathione synthesis. Alterations in the TSP and related pathways (transmethylation and remethylation) are altered in several neurodegenerative diseases, including Parkinson’s disease, suggesting their participation in the pathophysiology and progression of these diseases. In Parkinson’s disease many cellular processes are comprised mainly those that regulate redox homeostasis, inflammation, reticulum endoplasmic stress, mitochondrial function, oxidative stress, and sulfur content metabolites of TSP are involved in these damage processes. Current research on the transsulfuration pathway in Parkinson’s disease has primarily focused on the synthesis and function of certain metabolites, particularly glutathione. However, our understanding of the regulation of other metabolites of the transsulfuration pathway, as well as their relationships with other metabolites, and their synthesis regulation in Parkinson´s disease remain limited. Thus, this paper highlights the importance of studying the molecular dynamics in different metabolites and enzymes that affect the transsulfuration in Parkinson’s disease.

1 Introduction

The transsulfuration pathway (TSP) is a process by which the Hcy produced by transmethylation is irreversibly converted to cystine (Cys). The enzyme cystathionine β-synthase (CBS) catalyzes a condensation reaction of the amino acids Hcy and serine to form cystathionine; then, cystathionine γ-lyase (CSE) catalyzes a hydrolyzation reaction to generate Cys and α-ketobutyrate (Paul 2021). Cys is a building block amino acid for protein synthesis and is related to multiple pathways to generate sulfur-containing molecules with neuroprotective properties such as hydrogen sulfide (H2S), glutathione (GSH), and taurine. Cys participates in GSH synthesis by the enzyme ɣ-glutamylcysteine synthetase (GCS). Or to taurine synthesis by the enzyme cysteine dioxygenase (CDO). On the other hand, the gasotransmitter (H2S) is generated by the action of the enzymes CSE, CBS, and 3-mercapto pyruvate sulfurtransferase (3-MPST) having as intermediaries: Hcy, cystathionine, and Cys (Hensley and Denton 2015; Paul 2021; Sbodio et al. 2019).

TSP is a crucial part of sulfur metabolism and cellular redox regulation and is linked to providing methyl groups essential for optimal cell function (Sbodio et al. 2019). In the human brain, all disturbances of this pathway are associated with disorders like homocystinuria, Huntington’s disease, Alzheimer’s disease, PD, and aging (Paul 2021; Sbodio et al. 2019). In this review, we focused on the status of different molecules of the TSP and related pathways, including remethylation and transmethylation in PD.

2 Parkinsons disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuronal loss in the substantia nigra (SN) (Dickson 2018). Symptoms and signs of PD include rapid eye movement, sleep behavior disorder, and decreased smell in early pathology; motor symptoms, like bradykinesia, rigidity, rest tremor, and postural instability, become present in the late stages. Cognitive impairment and hallucinations can also be found in patients with advanced PD (Armstrong and Okun 2020). PD affects 1 % of the population above 60 years, and the peak incidence predominates between 70 and 79 years (Twelves et al. 2003; Tysnes and Storstein 2017). To this date, PD’s cause is uncertain; however, there is a strong association between environmental and genetic factors (5–10 %) (Olanow and Tatton 1999). Mutations can occur in different genes, including the α-synuclein (SNCA) gene, Parkin, PTEN-induced putative kinase one gene loci (PINK1), and DJ-1. The remaining cases are idiopathic (Nuytemans et al. 2010; Repici and Giorgini 2019; Simon et al. 2020). However, exposure to chemical compounds such as pesticides, solvents, metals, and toxicants in the laboral environment or diet increases the risk of PD (Simon et al. 2020).

Compounds such as volatile organic compounds, manganese derivates, and iron can cross the blood–brain barrier (BBB) and enter the brain. Once inside, they can trigger various responses in the central nervous system, including the generation of oxidative stress and the promotion of a pro-inflammatory environment through the activation of glial cells (Ogbodo et al. 2022; Verina et al. 2013; Zheng and Monnot 2012). When these insults occur alongside impaired clearance of SNCA, they can sustain chronic microglial activation. This sustained activation leads to increased production and release of pro-inflammatory and pro-oxidative mediators such as reactive oxygen species (ROS), interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and nitric oxide (NO). Thus, this sustained activation, in turn, contributes to the aggregation of SNCA aggregation and Lewy bodies formation (Li et al. 2010; Pathak and Sriram 2023). In PD, lewy bodies formation is associated with mitochondrial dysfunction (Mullin and Schapira 2013). These molecular events in the SN ultimately result in the loss of dopaminergic neurons (Henchcliffe and Beal 2008; Jankovic and Tan 2020; Olanow and Tatton 1999; Poewe et al. 2017).

All these dynamic processes and several repairing mechanisms could lead to pathophysiological processes and the irreversible cellular damage observed in PD (Jankovic and Tan 2020). PD can be approached pharmacologically and non-pharmacologically. Some of the pharmacological treatments include the dopamine precursor L-DOPA, complemented by catechol o-methyltransferase (COMT)-inhibitors extending the duration of L-DOPA effects; otherwise, the administration of MAO-B inhibitors (monoamine oxidase type B) are used to increase and extend synaptic dopamine concentrations (Poewe et al. 2017). Other pharmacological treatments include N-methyl-D-aspartate (NMDA) antagonists, serotonin re-uptake inhibitors, and tricyclic antidepressants. Non-pharmacological approaches (physical, speech, and occupational) and surgical treatments like deep brain stimulation are used in PD. Currently available therapy for PD helps many patients, though these drugs is linked to an increased risk of adverse events (Calne 1993).

3 Remethylathion, transmethylathion, and homocysteine in PD

Remethylation and transmethylation are two pathways closely interconnected to the TSP (Sbodio et al. 2019). During transmethylation, dietary methionine is adenylated to S-adenosylmethionine (SAM) in a reaction catalyzed by S-adenosylmethionine synthase (Stead et al. 2004). SAM is a methyl donor to biomolecules like DNA, RNA, proteins, and monoamine neurotransmitters (Al Mutairi 2020). Demethylation of SAM by methyl transferases (MT) generates S-adenosylhomocysteine (SAH), which then is finally hydrolyzed by SAH hydrolase to form homocysteine (Hcy) and adenosine (Brosnan et al. 2004; Hoffman et al. 1979). The Hcy can be re-methylated back to methionine via remethylation, where 5-methyltetrahydrofolate participates as a methyl donor to Hcy, yielding methionine and tetrahydrofolate in a reaction catalyzed by methionine synthase (MTR), using vitamin B12 as a cofactor. In the human brain, the enzyme methylenetetrahydrofolate reductase (MTHFR) transforms 5-10-methylenehydrofolate into 5-methyltetrahydrofolate (Martignoni et al. 2007; Selhub 1999).

Hcy, generated during transmethylation, is a sulfhydryl-containing amino acid derived from methionine (Al Mutairi 2020) that can be found in plasma, either free, reduced, or linked to proteins. The oxidized forms of Hcy are bound to amino acids such as Cys via disulfide linkages. Hcy, synthesized via the transmethylation pathway, can be either exported to the extracellular space, undergo a catabolic pathway, or even be remethylated or enter the TSP (Brosnan et al. 2004; Stead et al. 2004).

Hcy homeostasis is disrupted by genetic defects, age, lifestyle, nutritional deficiencies, and demographics, among other factors. The augmented concentration in the plasma of Hcy is known as hyperhomocysteinemia (HHcy) (McCully 2015). The etiology of HHcy is diverse, including gene defects and nutritional deficiencies (Kayadibi et al. 2014). According to different authors, HHcy leads to different anomalies in the organism’s functions, including in the central nervous system. For instance, many potential mechanisms are suggested for HHcy-induced brain damage, including oxidative stress, hypo-methylation of DNA and proteins, reticulum endoplasmic stress, cerebrovascular damage, neuroinflammation, and blood–brain barrier disruption. These are risk factors for neurovascular and neurodegenerative diseases like Alzheimer’s and PD (Kamat et al. 2016; Longoni et al. 2018; Tawfik et al. 2021; Yoon et al. 2014).

HHcy is a significant risk for vascular disease, cognitive decline, and dementia in older people (Yap 2003). Increased ischemic heart disease and cerebrovascular disease ratios have been reported in treated PD patients (Ben-Shlomo and Marmot 1995; Kim et al. 2021). HHcy was found in approximately 30 % of PD patients, related to the onset, progression, and development of cognitive decline of PD (Allain et al. 1995; Fan et al. 2020; Kuhn et al. 1998; Licking et al. 2017; Muller et al. 1999). Likewise, different animal studies have demonstrated that intracerebroventricular administration of Hcy decreases locomotor activity in rats and reduces striatal dopamine levels (Lee et al. 2005). Vasculopathies linked to Hhcy in PD include endothelial dysfunction and arterial stiffness, promoting neurovascular disintegration such as blood–brain barrier (BBB) breakdown in rodents and humans (Beard et al. 2011; Yoon et al. 2014). In this context, Hcy has been proposed to increase BBB permeability via activation of NMDAr regulation of tight junctions (Beard et al. 2011). Extracellular Hcy excitotoxicity via NMDARs increases calcium inflow, causing ROS and nitric oxide (NO) production. The increase in ROS production promotes a proinflammatory environment through nuclear factor κB (NF-κB), leading to neuronal injury (Figure 2) (Djuric et al. 2018; Mattson and Shea 2003). Experimental evidence demonstrates that HHcy sensitizes dopaminergic neurons to dysfunction and death by oxidative stress, mitochondrial dysfunction, and apoptosis in PD models and human neurons exposed to iron and rotenone (Duan et al. 2002). Hcy also promotes DNA damage preceding Hcy-induced oxidative stress and mitochondrial dysfunction. In cultured neurons treated with Hcy, ATP levels are depleted to repair Hcy-induced DNA damage (Kruman et al. 2000). The reduction of intracellular ATP levels is a crucial factor in the development of PD (Streck et al. 2003). Studies in humans and rats have supported L-DOPA treatments as the cause of elevated Hcy plasma levels (Miller et al. 2003; Yoon et al. 2014), The methylation of L-DOPA and dopamine to 3-omethyldopamine and 3-methoxytiramine respectively, depletes the SAM pool and of the available methyl groups, necessary for the remethylation of hcy to methionine, that leads to HHcy (Todorovic et al. 2006). In L-DOPA-treated PD patients, HHcy is reversed by supplementing folate and vitamin B12, which reduces Hcy concentrations (Lamberti et al. 2005a; Miller et al. 2003; Paul and Borah 2016). Vitamin B12 diet supplementation can increase Hcy catabolism, lowering the risk for cerebrovascular diseases, cognitive impairment, and dementia (Boushey et al. 1995; He et al. 2004). Likewise, COMT-inhibitors (COMT-I) prevent the L-DOPA-associated HHcy (Muller and Muhlack 2009). The methylation of L-DOPA by COMT produces SAH, which is converted to Hcy by SAH hydrolase. The chronically increased synthesis of SAM and Hcy exceeds the capacity of cells to metabolize Hcy, leading to HHcy (Lamberti et al. 2005b; Zoccolella et al. 2005). Thus L-DOPA-induced HHcy could be controlled by administering COMT-I or supplementation with B-vitamins (Lamberti et al. 2005a; Zoccolella et al. 2005).

HHcy is related to DNA hypomethylation and is highly correlated to increased plasma levels of SAH (Yi et al. 2000). HHcy inhibits SAH’s catalysis, enhancing SAH levels (Fan et al. 2020). SAH inhibits the methyltransferase, slowing down the methylation processes in the brain and leading neurons to apoptosis (Lin et al. 2008). Higher methylation potential (High SAM or low SAH levels) is related to better cognitive function in patients with PD; an inverse correlation between SAM and α-synuclein plasma levels has been described (Obeid et al. 2009). In this context, PD patients’ brains or peripheral blood show reduced DNA methylation in the promoter region and intron 1 of α synuclein-encoding gene (SNCA), indicating that this hypomethylation could contribute to elevated SNCA expression as seen in PD patients’ brains (Ai et al. 2014; Jowaed et al. 2010; Matsumoto et al. 2010). Also, within the cell, Hcy can be converted to Hcy thiolactone, triggering protein aggregation by incorporating Hcy residues into proteins, enhancing the probability of forming aggregates. Although it remains to be verified if Hcy could enhance α-synuclein aggregation as seen in PD (Jakubowski 2000). Table 1 shows all the associated metabolites to PD discussed in this paper.

Table 1:

Modulation of metabolites and enzymes of TSP involved in PD.

Homocysteine
Specie Sample Changes in metabolites/enzyme expression or activity References
PD patients Plasma Hcy versus healthy controls Dorszewska et al. (2007), Fan et al. (2020), Rodriguez-Oroz et al. (2009)
Serum Hcy versus patients with orthopedic disorders Kuhn et al. (1998)
Hcy versus healthy controls Bakeberg et al. (2019), dos Santos et al. (2009), Li et al. (2020), Todorovic et al. (2006)
Cerebroespinal fluid ↑ Hcy versus healthy controls Isobe et al. (2005)
PD patients L-DOPA treatment Plasma Hcy versus healthy controls (Muller et al. 1999; Religa et al. 2006)
Hcy vs non dementia PD with L-DOPA Yasui et al. (2000)
Hcy in C677T MTHFR versus PD before L-DOPA treatment in C677T MTHFR Ozkan et al. (2004)
Hcy versus PD with dopamine agonist and healthy controls Zoccolella et al. (2005)
Hcy versus PD with L-DOPA + COMT-I and healthy controls Nevrly et al. (2010)
Hcy versus PD with L-DOPA + COMT-I Yuan et al. (2009)
Hcy versus PD without L-DOPA treatment and healthy controls Rogers et al. (2003)
Serum Hcy versus PD without L-DOPA treatment Obeid et al. (2009)
Brain frontal cortex Hcy versus PD with DA-agonist, L-DOPA, L-DOPA + DA-agonist Kalecky et al. (2022)
PD patients treated with L-DOPA and decarboxylase inhibitors Plasma ↑ Hcy versus PD patients with L-DOPA + decarboxylase ihibitors + COMT-I Muller and Muhlack (2009)
PD patients with dementia Plasma ↑ Hcy versus no dementia PD and healthy controls

↑ Hcy versus no dementia PD and healthy controls
Slawek et al. (2013)



Song et al. (2013)
Mouse MTPT-induced PD model SN ↑ Hcy versus sham mice Yin et al. (2021)
Cells SH-SY5Y with MTPT ↑ Hcy versus non-treated Yin et al. (2021)

S-adenosylmethionine and S-adenosylcysteine

PD patient treated with L-DOPA and peripheral DOPA decarboxylase inhibitor Blood ↓ SAM versus healthy controls Cheng et al. (1997)
PD patients treated with L-DOPA Plasma ↑ SAH versus non L-DOPA PD patients Obeid et al. (2009)
PD patient with dementia Brain frontal cortex ↑ SAH versus non dementia PD patients Kalecky et al. (2022)
Rats treated with L-DOPA Brain tissue ↓ SAM versus non L-DOPA treated or with L-DOPA + COMT-I

↑ SAH versus non L-DOPA treated or with L-DOPA + COMT-I
Miller et al. (1997)

Cysteine

PD patients Plasma ↑ Cys versus sham mice Dorszewska et al. (2007)
Mouse MTPT-induced PD mode SN ↑ Cys versus control rats Yin et al. (2021)
Cells SH-SY5Y with MTPT ↑ Cys versus non treated cell culltures Yin et al. (2021)

H2S

Rat rotenone-induced PD model Substantia nigra ↓ H2S versus control rats Hu et al. (2010)
Mouse MPTP-induced PD model Plasma and striatum ↓ H2S versus control mice Yuan et al. (2018)
PC12 + MPP+ ↓ H2S versus non treated cell cultured Tang et al. (2011)

Cystathionine Β-synthase and cystathionine ɣ-LYASE

PC12 MPP+ ↓ CBS expression and activity Tang et al. (2011)
PD patients Analysis of microbiome ↓ CSE activity Hertel et al. (2019)

Glutathione and glutathione peroxidase

PD patient with severe damage to substantia nigra post-mortem Substantia nigra, putamen, frontal cortex ↓ GSH versus non severe SN PD patients Riederer et al. (1989)
Mouse 6-OHDA-induced PD model Substantia nigra ↓ GSH versus control mice Morroni et al. (2014)
PD patients Plasma ↑ GPx activity versus healthy controls Gokce Cokal et al. (2017)

Taurine

PD patients treated with L-DOPA Plasma

↓ Tau versus healthy controls and non L-DOPA treated PD patients Zhang et al. (2016)
Cerebrospinal fluid ↓ Tau versus healthy controls Araki et al. (1986), Engelborghs et al. (2003), Molina et al. (1997)

Specific genetic polymorphisms in genes encoding the MTHFR and MTR enzymes of the remethylation pathway have been associated with neurodegenerative diseases, including PD (Diao et al. 2019; Fong et al. 2011; Lionaki et al. 2022). Studies have described the relationship between PD and different MTHFR genotypes. In the Chinese population, it has been reported that the TT genotype of the rs1801133 variant and the AT haplotype of rs18011131-rs1801133 in the MTHFR gene are protective factors for PD; as well as the genotype AA in the rs13306560 variant in Mexican population (Garcia et al. 2017; Yuan et al. 2016). Thus, it is hypothesized that the reduced activity (TT genotype) or concentration (AA genotype) of MTHFR might be neuroprotective in brain when methionine levels are high, generation of GSH is compromised, or by a disruptive TSP (Garcia et al. 2017). In contrast, the reduced activity of TT genotype rs1801133 in L-DOPA treated PD patients, combined with low folate ingestion, impairs the remethylation causing HHcy in PD patients (Yasui et al. 2000). Meanwhile, the CC of the rs1801133 genotype was associated with sporadic Parkinson’ss disease (SPD) in the Mexican and Italian populations; this genotype has the highest decrease of DNA methylation in comparison to the TT genotype in folate depletion conditions (Garcia et al. 2015; Valleet al. 2014).

4 Cysteine

The Cys produced during TSP, is a semi-essential amino acid that contains sulfur and a polar group, which provides hydrophilic properties to the molecule. This amino acid can be found inside the cell as Cys, but extracellular in an oxidative environment, is predominantly present in a dimeric form known as cystine (Cys2) (Paul et al. 2018; Rehman et al. 2020). The Endogenous Cys synthesis is by TSP. Initially, Hcy condensates with serine by the enzymatic action of cystathionine β-synthase (CBS) to form cystathionine, then this molecule reacts with cystathionine γ-lyase (CSE), to finally produce Cys (Singh et al. 2009).

Cys functions occur in different processes, essential in building fatty acids, enabling the synthesis of cell membranes and the myelin sheaths of neural cells to protect neurons from oxidative stress and its repercussions (Weimbs and Stoffel 1992). Cys is a rate-limiting substrate of the synthesis of GSH, the precursor of taurine, and coenzymeA (CoA). It is relevant to mention that Cys is also a proteinogenic amino acid that takes part in up to 2 % of proteins in the body and is involved in different posttranslational modifications like sulfhydration, palmitoylation, glutathionylation, guanylation, cysteinylation, sumoylation, farnesylation, and nitrosylation (Paul et al. 2018).

Increased levels of Cys are considered neurotoxic in the central nervous system via the overactivation of NMDAr receptors evoking neuronal death and potentiating the Ca2+ influx (Janaky et al. 2000). Elevated plasma levels of Cys to sulfate ratios were found in patients with PD and Alzheimer’s disease (Heafield et al. 1990; Stipanuk et al. 2006). The primary enzymatic route for cysteine breakdown is catalyzed by cysteine dioxygenase (CDO), in which molecular oxygen is added to the sulfhydryl group of Cys. This reaction keeps Cys levels below the toxicity threshold and forms less toxic products than Cys, such as sulfate and taurine (Galvan et al. 2012). In this sense, it has been suggested a reduction in CDO activity in PD patients (Heafield et al. 1990). Studies in rats have shown that CDO is present in the substantia nigra of rats and is degraded by the ubiquitin-26 S proteasome system. The 26 S proteasome recognizes and degrades the ubiquitin–protein conjugates (Dominy et al. 2006; Parsons et al. 2001). A characteristic feature of PD is the presence of Lewy bodies containing free and ubiquitinated proteins. Lewy bodies’ formation is linked to the ubiquitin-proteosome system failing, possibly leading to aberrant cysteine oxidation by CDO (Jameson 2011; McNaught et al. 2001).

Also, Cys neurotoxicity has been linked to the formation of many neurotoxic compounds (Janaky et al. 2000). Cys may generate oxygen-free radical species by Haber-Weiss-type reactions when Cys interacts with transition metal ions like Fe, which are highly present in the substantia nigra of post-mortem PD patients (Sofic et al. 1988). Catecholamines, like dopamine, also form neurotoxic compounds by the nucleophilic addition of Cys to oxidize catechols, forming cysteinylcatechols (Janaky et al. 2000). Cysteinylcatechols are described as contributors to excitotoxic neurodegeneration, principally via mitochondrial dysfunction, increasing sensitivity to endogenous NMDAr agonists (Montine et al. 1997). Cysteine can also form adducts with L-DOPA and 3,4-dihydroxyphenylacetic acid (DOPAC, metabolite of dopamine degradation). The levels of cysteinyl adducts of L-DOPA, dopamine, and DOPAC, significantly increase in the substantia nigra of PD patients (Spencer et al. 1998). Contributing to oxidative stress damage by inhibiting mitochondrial complex I, a hallmark of PD (Danielson and Andersen 2008). Cys is metabolized into three main compounds: hydrogen sulfide (H2S), taurine, and glutathione, as mentioned below.

5 Hydrogen sulfide

H2S is a gas molecule known to be toxic, colorless, and a smell similar to rotten eggs. Numerous studies have revealed the role H2S plays in physiological and pathological regulation in the brain of mammals. The metabolism of H2S is involved in neurodegenerative disorders, including PD. Evidence suggests that H2S production is impaired in the progression of PD (Cao et al. 2018). Hu et al. have shown that H2S levels were lower in rats lesioned unilaterally in the striatum with 6-hydroxydopamine (a PD rat model) in contrast with sham-operated rats (Hu et al. 2010).

Currently, H2S is considered a signaling molecule, a gasotransmitter, an antiapoptotic agent, an antioxidant, and a neuroprotector in the nervous system (Kumar et al. 2018). Different studies have demonstrated the neuroprotective properties of H2S in different rodent and cellular models of PD. Some neuroprotective effects of H2S are a consequence of the support it provides to the mitochondria function because, in lower concentrations, H2S stimulates mitochondrial energetics, enhancing adenosine triphosphate (ATP) production and activation of protein kinase A (PKA) (Paul and Snyder 2015). H2S can also prevent neuronal damage produced by endoplasmic reticulum stress, which can result in endothelial cell apoptosis (Zhong et al. 2020). Depending on the scenario, H2S stimulates or inhibits autophagy, a process essential for the degradation and recycling of cellular components. Autophagy disturbances are involved in pathological changes in many neurodegenerative disorders (Wu et al. 2018).

Furthermore, H2S can protect neural cells from oxidative stress. H2S reduces Cys2 into Cys in the extracellular space for GSH production and makes cells more efficient in Cys transport into neurons (Kimura et al. 2010). Alternatively, the direct effects of H2S are as a scavenger of reactive oxygen species (ROS) as well as peroxynitrites (ONOO) and as a reducing agent of glutathione disulfide (GSSG) (Xiao et al. 2018).

Figure 1: 
The role of glutathione and cysteine in astrocytes and dopaminergic neurons in Parkinson’s disease. Extracellular cystine (Cys2) is transported into the astrocyte via Cys2/glutamate (xCT), and then reduced into cysteine (Cys) by glutathione (GSH). Inside astrocytes, Cys can form cysteinyl adducts or produce GSH, which MRP1 (Multidrug resistance protein 1) can abstract from the inside in a reaction catabolized by ɣ-glutamyltranspeptidase (ɣ-GT), resulting in L-cysgly or L-cysgly conjugate. L-cysgly is hydrolyzed to Cys and glycine (gly), precursors of GSH, which are taken up by the dopaminergic neuron via the excitatory amino-acid carrier 1 (EAAC1). In PD, GSH levels and GPX are decreased in dopaminergic neurons and accompanied by increased levels of cysteinyl adducts, anion superoxide (O2−), hydrogen peroxide (H2O2), hydroxyl radical (OH•) and enhanced activity of ɣ-GT.
Figure 1:

The role of glutathione and cysteine in astrocytes and dopaminergic neurons in Parkinson’s disease. Extracellular cystine (Cys2) is transported into the astrocyte via Cys2/glutamate (xCT), and then reduced into cysteine (Cys) by glutathione (GSH). Inside astrocytes, Cys can form cysteinyl adducts or produce GSH, which MRP1 (Multidrug resistance protein 1) can abstract from the inside in a reaction catabolized by ɣ-glutamyltranspeptidase (ɣ-GT), resulting in L-cysgly or L-cysgly conjugate. L-cysgly is hydrolyzed to Cys and glycine (gly), precursors of GSH, which are taken up by the dopaminergic neuron via the excitatory amino-acid carrier 1 (EAAC1). In PD, GSH levels and GPX are decreased in dopaminergic neurons and accompanied by increased levels of cysteinyl adducts, anion superoxide (O2), hydrogen peroxide (H2O2), hydroxyl radical (OH) and enhanced activity of ɣ-GT.

Different studies have demonstrated that inhalation and intraperitoneal administration of H2S prevents the death of dopaminergic neurons, ameliorates movement disruption, and alleviates astrocytic activation in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD-mouse model, MPTP is a prodrug of the neurotoxin 1-methyl-4-phenylpyridinium (MPP+), causing permanent symptoms of PD in rodents. This protection is conferred by the activation of heme oxygenase and gcs genes, by the uncoupling protein 2 (UCP2)–dependent mechanism, reducing ER stress and apoptosis, and by the attenuation in the increases of ROCK2 (Rho-associated protein kinase 2) through miR-135a-5p by MPTP. ROCK2 is implicated in neurodegenerative processes, including axonal degeneration and neuronal death in the brain (Kida et al. 2011; Liu et al. 2016; Lu et al. 2012). Administration of the NaHS and H2S donor reversed the progression of movement dysfunction and loss of tyrosine-hydroxylase in the substantia nigra of a 6-hydroxidopamine (6-OHDA) and rotenone rat PD models. The proposed mechanism for NaHS-protection is by inhibiting NADPH oxidase activity and oxygen consummation induced by 6-OHDA. Already that NaHS reduce the expression and translocation to the cytoplasmatic membrane of the p47phox, a subunit of NADPH oxidase (Chen et al. 2015; Hu et al. 2010). NaHS also has anti-inflammatory properties through the inhibition of the microglial activation in the substantia nigra and accumulation of pro-inflammatory factors, such as NO and TNFα in the striatum, via NF-кB (Chen et al. 2015; Hu et al. 2010). Moreover, in vitro studies with PC12 and SH-SY5Y cells also demonstrate the protection of H2S against MPP+, rotenone, and 6-OHDA-induced neuronal damage by enhancing mitochondrial functions, mitochondrial potential membrane channel, attenuating intracellular ROS production, apoptosis, and endoplasmic reticulum stress (Hu et al. 2009; Tiong et al. 2010; Xie et al. 2012; Yin et al. 2009).

H2S also modifies many proteins in a mechanism that involves the transformation of protein Cys residues to form protein persulfides, also known as S-sulfhydration (Filipovic 2015). S-sulfhydration (S-SH) modification is a posttranslational process involved in many physiological and pathological processes, like the inflammatory response, cell differentiation, oxidative stress, or neuroprotection (Zhang et al. 2017). Aberrant sulfhydration patterns occur in neurodegenerative conditions such as PD (Paul and Snyder 2015). The E3 ubiquitin ligase, Parkin, suffers sulfhydration by H2S, which occurs mainly in Cys95, Cys59, and Cys182; Parkin sulfhydration enhances its catalytic activity, whereas nitrosylation (oxidative modification of Cys by nitric oxide) inactivates Parkin (Paul and Snyder 2018; Vandiver et al. 2013). The nitrosylation of Parkin inhibits its E3 ligase responsible for the clearance of toxic misfolded proteins (Kida and Ichinose 2015; Vandiver et al. 2013). Parkin nitrosylation is enhanced, and Parkin sulfhydration is decreased in PD brains, indicating a possible reduction of endogenous H2S production and enhanced nitrosative stress in the progression of PD (Chung et al. 2004; Vandiver et al. 2013).

Other strategies have also been designed to evaluate the effects of H2S. Xie et al. observed that the H2S-releasing L-DOPA derivate, ASC84, this compound attenuates oxidative stress by activating the Nrf2 transcription factor in a 6-OHDA-PD induced rat model (Xie et al. 2013). The proposed mechanism for the activation of Nrf2 described is by the S-sulfhydration of Keap1 (Nrf2 inhibitor) at Cys-151, releasing Nrf2 from Keap1 inhibition, activating Nrf2 in the 6-OHDA PD-induced rat model (Yang et al. 2013). Compound GYY4137, another H2S releaser, is neuroprotective and reduced nitrated α-synuclein in an MPTP mouse PD model. α-synuclein tyrosine residues can be nitrated by peroxynitrite when excessive NO is generated, thus facilitating α-synuclein protein aggregation (Hou et al. 2017).

5.1 Enzymatic H2S production in PD

Four enzymes are responsible for H2S biosynthesis in the brain, including CBS, CSE, 3-mercaptopyruvate sulfur transferase, which acts together with cysteine aminotransferase (3-MPST/CAT) or with D-amino acid oxidase (3-MPST/DAO) (Chen et al. 2015). CBS and CSE generate H2S in the cytosol and are pyridoxal-5′ phosphate (PLP)-dependent enzymes, while 3MST produces H2S in mitochondria and is PLP-independent (Cao et al. 2018).

The enzyme CBS has the property to transform Cys and Hcy into H2S and can either catabolize Hcy to the Cys precursor cystathionine (Miles and Kraus 2004). In contrast, CSE can generate Cys from cystathionine but favors the enzymatic production of H2S from Cys or Hcy (Sbodio et al. 2019). 3-mercaptopyruvate (3 MP) is the substrate of the enzyme 3MPST producing H2S under reducing conditions; 3 MP is provided from the metabolism of Cys and α-ketoglutarate due to the action of the enzyme Cysteine aminotransferase (CAT) or by the enzymatic activity of D-amino acid oxidase (DAO) using D-cysteine (Chen et al. 2015; Shibuya et al. 2009; Zhong et al. 2020). On the other hand, the production of H2S by 3-MPST is accompanied by the production of polysulfides, which are an endogenous reservoir of sulfur in the absence of GSH and Cys (Augsburger and Szabo 2020; Tabassum and Jeong 2019).

In general, CBS is recognized as the dominant H2S-producing enzyme in the brain, while CSE may not contribute to H2S generation in this organ since CSE inhibition does not alter the production of H2S (Abe and Kimura 1996). Elevated plasma levels of cystathionine produced by CBS are accumulated over time in PD, while Cys levels were not modified over time (Hertel et al. 2019). Studies from Diwakar in 2007 have demonstrated that even though the activity of the CSE in the mouse brain represents only 1 % of the liver, CSE inhibition by oxidative stress alters GSH levels since CSE is a rate-limiting enzyme for Cys synthesis from cystathionine; thus CSE activity maintains GSH homeostasis in the brain and preserves mitochondrial function, which is altered in PD patients (Diwakar and Ravindranath 2007). In addition, H2S is also produced in the brain by the activity of 3-MPST (Kimura et al. 2015). Shibuya et al. (2009) have demonstrated that brain homogenates of CBS-knockout mice can produce H2S via 3-MPST enzyme in similar levels as wild-type mice (Shibuya et al. 2009).

CBS and CSE are present in astrocytes and microglial cells, while 3-MPST is localized in neurons (Lin et al. 2021). H2S production in glial cells attenuates inflammatory responses, protecting neurons from PD in rodent models where activated glial cells were induced by inflammation. In vivo studies have demonstrated a significant decrease in CBS expression in the MPTP PD mouse model (Yuan et al. 2018). Striatal CBS gene overexpression in 6-OHDA and MPTP PD-induced rodent models enhances H2S production and is neuroprotective, preventing dopaminergic cell death (Yin et al. 2017; Yuan et al. 2018). Also, a significant decrease in CBS expression was observed in MPP+−exposed astrocytes and microglia but not in dopaminergic neurons (Yuan et al. 2018). Likewise, DJ-1 knockout astrocytes have reduced H2S and CBS production (Bae et al. 2013). CBS transcription and protein expression are also decreased in rotenone-treated microglia. While the overexpression of CBS in microglia reduces the expression of pro-inflammatory genes and enhances anti-inflammatory markers in response to rotenone stimulation (Du et al. 2014). As mentioned, reduced sulfhydrated parkin has been observed in PD post-mortem patients compared to healthy post-mortem subjects (Paul and Snyder 2018). Overexpression of CBS in neuronal cells increases Parkin sulfhydration related to enhanced Parkin activity and H2S production (Vandiver et al. 2013). The role of the H2S-generating enzymes in the development of PD is not yet fully elucidated.

6 Glutathione

Glutathione (GSH) is a linear thiol-containing peptide present in every cell, particularly abundant in the liver and kidney (Commandeur et al. 1995). In the brain, GSH concentration ranges from 1 to 2 mM, and astrocytes appear to have higher GSH levels than neurons (Dringen 2000; Rae and Williams 2017). In the presence of oxide radicals and during the enzymatic detoxification of peroxides, GSH is oxidized to GSSG (GSH disulfide) (Dringen et al. 2000). Under normal conditions, GSH is the most prevalent in the brain (97 %) (Iskusnykh et al. 2022).

Thanks to numerous studies, GSH is known to have a large range of functions. GSH can function as a physiological reservoir for Cys and glutamate (Aoyama 2021; Koga et al. 2011). In the brain, it is an essential antioxidant able to protect brain cells from damage produced by ROS, RNS, and other reactive species like hydroxyl radicals, peroxynitrites, and superoxide radicals (Asanuma and Miyazaki 2021; Bjorklund et al. 2021; Dringen and Hirrlinger 2003). The proportion of reduced and oxidized GSH (GSH/GSSG) is used as a biomarker of cellular redox homeostasis (Bjorklund et al. 2021). As well, GSH can protect the organism from inflammatory pathologies and xenobiotic factors (Ghezzi 2011; Sipes et al. 1986). Also participates in the transport of some amino acids and ensures the thiol group in proteins (Griffith et al. 1979; Iskusnykh et al. 2022).

De novo synthesis of GSH is dependent on the “rate limiting precursor,” Cys. This amino acid enters the cell from plasma or through the transmethylation and transsulfuration pathways (Asanuma and Miyazaki 2021; Bjorklund et al. 2021; Iskusnykh et al. 2022). Since GSH cannot cross the brain–blood barrier (BBB), neurons and astrocytes need to produce their own GSH (Aoyama 2021). Extracellular Cys is easily auto-oxided to Cys2 and is principally transported into astrocytes via Cys2/glutamate (xCT) antiporter. Cys2 is taken via xCT into the cell and then is reduced by GSH or thioredoxin to Cys for GSH synthesis (Asanuma and Miyazaki 2021; Mandal et al. 2010). In general, GSH synthesis depends on the activity of the enzyme ɣ-glutamylcysteine synthetase (ɣ-GCS), glutathione synthetase (GS), and through pathways that include its catabolism. GSH catabolism occurs extracellularly through the activity of a membrane ectoenzyme by the Ɣ-glutamyltranspeptidase (ɣ-GT), which hydrolyzes the gamma-glutamyl bond of extracellular GSH or GSH conjugates (Franco et al. 2007). ɣ-GT catalyzes transfers of the ɣ-glutamyl moiety from GSH, or its glutathione conjugates, onto an acceptor; the product of this reaction is L-cysgly or L-cysgly conjugate. Then L-cysgly is hydrolyzed to Cys and glycine, which can be taken up by neurons via excitatory amino-acid carrier 1 (EAAC1) and used as precursors for GSH synthesis; thus, GSH synthesis in neurons depends on the GSH synthesis by surrounding astrocytes (Asanuma and Miyazaki 2021; Valdovinos-Flores and Gonsebatt 2012).

Evidence has demonstrated that oxidative stress plays an important role in the pathophysiology of PD. Post-mortem studies of PD patients reveal lower levels of the antioxidant GSH only in the substantia nigra (40 %) in comparison to control patients, and no depletion in other brain regions was observed (Sian et al. 1994). In addition, the decrease in GSH levels is accompanied by a reduction in the GSH/GSSG ratio in brain tissue and blood of PD patients in comparison to healthy subjects (Bjorklund et al. 2021). The reduction of GSH levels in PD patients is not at all well understood. In different studies, no failure has been found in GSH synthesis since ɣ-GCS activity, like glutathione S-transferase in the substantia nigra, is normal in PD patients. Nevertheless, changes in ɣ-GT and glutathione peroxidase (GPx) were observed in the tissue and blood of patients with PD (Power and Blumbergs 2009; Sian et al. 1994). The enhanced activity of ɣ-GT in PD patients might reflect a compensatory requirement of GSH precursors for dopaminergic neurons. If Cys is not used for GSH synthesis, it forms cisteynil adducts with L-DOPA, dopamine, and DOPAC. These conjugates easily form cytotoxic compounds, which are irreversible complex I mitochondrial inhibitors (Li and Dryhurst 1997; Shen and Dryhurst 1996). Secondly, GPx catalyzes the reduction of H2O2 to water, using GSH to protect cells against oxidative damage. Lower levels of GPx were detected in the blood cells of PD patients (Vida et al. 2019). In contrast, studies from Power and Blumges in 2009 have demonstrated in human brain tissue that GPx1 is highly expressed in microglia and has lower levels in neurons. In the same research, GPx-1 positive microglia were hypertrophied and more abundant in PD tissues, making contacting multiple neurons, proposing that the upregulated levels of the antioxidant GPx-1 protect neurons from oxidative stress (Power and Blumbergs 2009). Different studies have demonstrated that increased oxidative stress and decreased GSH/GSSG activity in the brain of PD patients might boost chronic inflammatory reactions, mitochondrial superoxide, as well as oxidative damage to biomolecules (Dias et al. 2013; Hauser and Hastings 2013).

In the dopaminergic cell, dopamine oxidation occurs in an enzyme-dependent or enzyme-independent manner to produce dopamine quinones and active radicals. Enzymatic oxidation of dopamine by monoamine oxidase leads to the formation of H2O2 and metabolites such as 3,4-dihydroxybenzoic acid (DOPAC) and homovanillic acid (HVA). The H2O2 is inactivated by catalase or GPx, which uses GSH as a co-substrate. Nevertheless, H2O2 may form highly reactive hydroxyl radicals (OH) in excess iron. OH are directly neutralized with GSH in a non-enzymatic reaction (Figure 1) (Fiser et al. 2013).

In contrast, spontaneous dopamine oxidation leads to neuromelanin formation and can generate dopamine-quinone, semiquinone species, and superoxide anion (O2) (Bjorklund et al. 2018; Zhang et al. 2019). Dopamine-quinones exert their toxic effects by binding to sulfhydryl residues on functional proteins, such as tyrosine hydroxylase (TH), dopamine transporter, and parkin, declining protein function and evoking dopaminergic toxicity (Asanuma and Miyazaki 2021; Kuhn et al. 1999; LaVoie et al. 2005; Whitehead et al. 2001). GSH binds to DA quinones via its thiol group, preventing dopaminergic toxicity. Therefore, GSH is critical for the protection of DA neurons in the substantia nigra pars compacta from dopamine-quinone and free radicals neurotoxicity. The loss of the neuroprotective functions of GSH in dopaminergic neurons in the substantia nigra pars compacta may lead to the neurodegenerative processes observed in PD (Andersen 2001; Liddell and White 2018; Smeyne and Smeyne 2013). Figure 1 summarizes the main functions of glutathione and cysteine in astrocytes and dopaminergic neurons in PD.

7 Taurine

Taurine (Tau) is a semi-essential amino acid that contains a sulfur group, endogenously produced from Cys (Chen et al. 2019; Jakaria et al. 2019). The body has different alternatives to get Tau; one is by dietary intake, and from de novo synthesis through the catabolism of Cys which however is limited by the oxidation of hypotaurine to Tau (Wojcik et al. 2010). The enzymes cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSAD) are in charge of producing hypotaurine from Cys (Rafiee et al. 2022). At the same time, cysteamine dioxygenase (ADO) synthesizes Tau from cysteamine instead of Cys as substrate (Dominy et al. 2004). In the brain, ADO expression predominates from CDO expression (Dominy et al. 2007). Tau is mainly produced in the liver and kidney; however, it has also been found in other tissues, including the brain (El Idrissi 2019; Park et al. 2014). In the rat brain, Tau is expressed in all regions (Chen et al. 2019). Tau content in the brain is mainly transported from the periphery and by the local synthesis from de novo catabolism of Cys, both in neurons and astrocytes (Vitvitsky et al. 2011).

Tau concentration levels in the brain vary in the different developmental stages. A high concentration of Tau has been described in the developing brain, decreasing levels in adulthood even more in older stages of different brain species (Baliou et al. 2021; Rafiee et al. 2022), proposing Tau as an essential player in neurodevelopment, including neurite growth and synaptogenesis (Mersman et al. 2020). Studies in mice reported that tissue depletion of Tau leads to a shorter lifespan (Ito et al. 2014). In the brain, Tau is involved in numerous processes in brain cells, acting as an anti-inflammatory, neuromodulator, and osmoregulator (Chen et al. 2019; Niu et al. 2018; Rafiee et al. 2022). Tau has been reported as a neuroprotective agent against excitotoxicity, apoptosis death, reticulum endoplasmic stress, mitochondrial stress, and oxidative stress (Leon et al. 2009; Pan et al. 2010; Pan et al. 2012; Rafiee et al. 2022; Wu et al. 2005).

Levels of Tau in the plasma of PD patients are decreased compared to control patients and are negatively associated with motor severity (Zhang et al. 2016). Dawson et al. (1999) have demonstrated that age-related reductions of striatal Tau and dopamine are correlated in aged rats, suggesting neuronal dopaminergic degeneration (Dawson et al. 1999).

Different studies have demonstrated that taurine exerts neuroprotection in cells and murine models of PD through the inactivation of microglia-mediated neuroinflammation (Che et al. 2018; Hou et al. 2018; Tian et al. 2020; Wang et al. 2021). In the dopaminergic neuron, high levels of iron and dopamine oxidation make neurons more vulnerable to oxidative stress and, in specific ferric iron induces aggregation of SNCA (Jellinger 1999; Li et al. 2010). Dopamine autoxidation is catalyzed by metals such as iron and manganese. Studies in vitro have demonstrated that Tau significantly reduced ferric iron, and manganese stimulated dopamine oxidation in vitro, thus protecting dopaminergic neurons from ROS-induced oxidative stress (Figure 2) (Dawson et al. 2000).

Tau is a neuromodulator of gamma-aminobutyric acid (GABA), glycine, and NMDA receptors and is found in high concentrations in the substantia nigra and striatum, mainly observed in GABAergic terminals coming from the striatum to the substantia nigra pars reticulate (Bianchi et al. 1998; Dray and Straughan 1976; Palkovits et al. 1986). Studies in rat brain slices have demonstrated that Tau acts as a neuroprotector agent against MPP + neurotoxicity via the activation of GABAA receptors (O’Byrne and Tipton 2000). Studies in rat brain slices reported that inhibition by Tau in the substantia nigra pars compacta is mediated by GABA receptors (Ye et al. 1997). Thus Tau could be inhibiting the PD-induced hyperactive projection from the subthalamic nucleus to substantia nigra pars reticulata, disinhibiting the motor thalamus and generating movement (Dray and Straughan 1976; Menzie et al. 2014). Likewise, Tau plays a vital role in the modulation of the release and metabolism of striatal dopamine by the glycine activation, in turn enhancing the activity of dopaminergic neurons of the ventral tegmental area, enhancing dopamine levels in the striatum (nucleo accumbens) (Ericson et al. 2013; Ruotsalainen and Ahtee 1996). Figure 2 Associates the pro-inflammatory and oxidative events in Parkinson’s disease and different compounds of the transsulfuration pathway. Figure 3 shows the transsulfuration pathway in PD in which the previously described molecules are involved (Figure 3).

Figure 2: 
Association of pro-inflammatory and oxidative events in Parkinson’s disease and different compounds of the transsulfuration pathway. Chemical compounds such as manganese (Mn), iron (Fe), and volatile organic compounds (VOC) can cross the blood-brain barrier (BBB). Once inside the brain, along with impaired clearance of α-synuclein (SNCA), they induce microglia to release inflammatory and pro-oxidative mediators, including tumor necrosis factor (TNFα), interleukin 1β (IL1β), transforming growth factor β (TGFβ), nitric oxide (NO), and reactive oxygen species (ROS). This leads to SNCA aggregation and stimulates astrocytes to release TNFα, IL-1β, NO, ROS, and interleukin 6 (IL-6), promoting dopaminergic injury and death. Fe additionally induces ROS generation and SNCA fibrillation and aggregation. Compounds of the transsulfuration pathway (TSP) are closely related to the events described above. Homocysteine (Hcy) increases BBB permeability, NO, ROS, and proinflammatory cytokines through N-methyl-D-aspartate receptor (NMDAr) activation, favoring dopaminergic neuron death. Reduced levels of hydrogen sulfide (H2S), taurine (Tau), and glutathione (GSH) promote oxidative stress and inflammation in neurons, inducing SNCA aggregation and dopaminergic neuron damage.
Figure 2:

Association of pro-inflammatory and oxidative events in Parkinson’s disease and different compounds of the transsulfuration pathway. Chemical compounds such as manganese (Mn), iron (Fe), and volatile organic compounds (VOC) can cross the blood-brain barrier (BBB). Once inside the brain, along with impaired clearance of α-synuclein (SNCA), they induce microglia to release inflammatory and pro-oxidative mediators, including tumor necrosis factor (TNFα), interleukin 1β (IL1β), transforming growth factor β (TGFβ), nitric oxide (NO), and reactive oxygen species (ROS). This leads to SNCA aggregation and stimulates astrocytes to release TNFα, IL-1β, NO, ROS, and interleukin 6 (IL-6), promoting dopaminergic injury and death. Fe additionally induces ROS generation and SNCA fibrillation and aggregation. Compounds of the transsulfuration pathway (TSP) are closely related to the events described above. Homocysteine (Hcy) increases BBB permeability, NO, ROS, and proinflammatory cytokines through N-methyl-D-aspartate receptor (NMDAr) activation, favoring dopaminergic neuron death. Reduced levels of hydrogen sulfide (H2S), taurine (Tau), and glutathione (GSH) promote oxidative stress and inflammation in neurons, inducing SNCA aggregation and dopaminergic neuron damage.

Figure 3: 
The transsulfuration pathway in Parkinson’s disease. The figure shows an overview of the modulation of different enzymes and metabolites of the transsulfuration pathway (TSP) in PD. TSP generates cysteine (Cys) from homocysteine (Hcy), which in turn is synthesized from methionine during transmethylation, having as intermediates S-adenosylhomocysteine (SAH) and the methyl donor S-adenosyl methionine (SAM). Hcy can be remethylated to methionine by the activity of the enzyme methylenetetrahydrofolate reductase (MTHFR). Then Hcy is converted to cysteine (Cys) by the activity of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), having cystathionine as an intermediate. Likewise, Cys is a precursor of different molecules, including glutathione (GSH), taurine, and hydrogen sulfide (H2S). GSH is synthesized from Cys by the activity of ɣ-glutamylcysteine synthetase (ɣ-GCS) and glutathione synthetase (GS); taurine by the activity of cysteamine dioxygenase (ADO), cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSAD); and finally, H2S by the activity of CBS, CSE, and 3-mercaptopyruvate sulfur transferase (3-MPST) in conjunction with cysteine aminotransferase (3-MPST/CAT) or (3-MPST/DAO). The down black arrow or up red arrow denotes the downregulation and upregulation respectively, in metabolites or enzymes of the TSP in PD. Association of pro-inflammatory and oxidative events in Parkinson’s disease and different compounds of the transsulfuration pathway. Chemical compounds such as manganese (Mn), iron (Fe), and volatile organic compounds (VOC) can cross the blood-brain barrier (BBB). Once inside the brain, along with impaired clearance of α-synuclein (SNCA), they induce microglia to release inflammatory and pro-oxidative mediators, including tumor necrosis factor (TNFα), interleukin 1β (IL1β), transforming growth factor β (TGFβ), nitric oxide (NO), and reactive oxygen species (ROS). This leads to SNCA aggregation and stimulates astrocytes to release TNFα, IL-1β, NO, ROS, and interleukin 6 (IL-6), promoting dopaminergic injury and death. Fe additionally induces ROS generation and SNCA fibrillation and aggregation. Compounds of the transsulfuration pathway (TSP) are closely related to the events described above. Homocysteine (Hcy) increases BBB permeability, NO, ROS, and proinflammatory cytokines through N-methyl-D-aspartate receptor (NMDAr) activation, favoring dopaminergic neuron death. Reduced levels of hydrogen sulfide (H2S), taurine (Tau), and glutathione mmm(GSH) promote oxidative stress and inflammation in neurons, inducing SNCA aggregation and dop.
Figure 3:

The transsulfuration pathway in Parkinson’s disease. The figure shows an overview of the modulation of different enzymes and metabolites of the transsulfuration pathway (TSP) in PD. TSP generates cysteine (Cys) from homocysteine (Hcy), which in turn is synthesized from methionine during transmethylation, having as intermediates S-adenosylhomocysteine (SAH) and the methyl donor S-adenosyl methionine (SAM). Hcy can be remethylated to methionine by the activity of the enzyme methylenetetrahydrofolate reductase (MTHFR). Then Hcy is converted to cysteine (Cys) by the activity of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), having cystathionine as an intermediate. Likewise, Cys is a precursor of different molecules, including glutathione (GSH), taurine, and hydrogen sulfide (H2S). GSH is synthesized from Cys by the activity of ɣ-glutamylcysteine synthetase (ɣ-GCS) and glutathione synthetase (GS); taurine by the activity of cysteamine dioxygenase (ADO), cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSAD); and finally, H2S by the activity of CBS, CSE, and 3-mercaptopyruvate sulfur transferase (3-MPST) in conjunction with cysteine aminotransferase (3-MPST/CAT) or (3-MPST/DAO). The down black arrow or up red arrow denotes the downregulation and upregulation respectively, in metabolites or enzymes of the TSP in PD. Association of pro-inflammatory and oxidative events in Parkinson’s disease and different compounds of the transsulfuration pathway. Chemical compounds such as manganese (Mn), iron (Fe), and volatile organic compounds (VOC) can cross the blood-brain barrier (BBB). Once inside the brain, along with impaired clearance of α-synuclein (SNCA), they induce microglia to release inflammatory and pro-oxidative mediators, including tumor necrosis factor (TNFα), interleukin 1β (IL1β), transforming growth factor β (TGFβ), nitric oxide (NO), and reactive oxygen species (ROS). This leads to SNCA aggregation and stimulates astrocytes to release TNFα, IL-1β, NO, ROS, and interleukin 6 (IL-6), promoting dopaminergic injury and death. Fe additionally induces ROS generation and SNCA fibrillation and aggregation. Compounds of the transsulfuration pathway (TSP) are closely related to the events described above. Homocysteine (Hcy) increases BBB permeability, NO, ROS, and proinflammatory cytokines through N-methyl-D-aspartate receptor (NMDAr) activation, favoring dopaminergic neuron death. Reduced levels of hydrogen sulfide (H2S), taurine (Tau), and glutathione mmm(GSH) promote oxidative stress and inflammation in neurons, inducing SNCA aggregation and dop.

8 Concluding remarks

In this review, we highlighted and offered a summary of the role of different intermediates, products, and enzymes related to TSP. This pathway maintains redox homeostasis, integrates stress responses, and synthesizes various molecules with many functions in the brain (antioxidant, antiapoptotic, neuromodulator, structural, reducing power, etc.). Low methylation potential (SAM/SAH) is found in PD patients and is influenced by the transmethylation and remethylation pathway, ingesting folates and vitamin B12, and the pharmacological treatment for PD. This methylation potential regulates TSP, since it inversely regulates Hcy levels and directly regulates CBS activation for H2S synthesis. The TSP products, H2S and Cys, are downregulated and upregulated in PD. Although Cys levels are elevated, the products of its metabolism (GSH, taurine, and H2S) are decreased in PD, possibly due to the down-regulation of enzymes related to its synthesis and greater consumption of these molecules due to the increase in the generation of ROS in PD (Dias et al. 2013; Heafield et al. 1990). GSH, taurine, and H2S are molecules with anti-inflammatory and antioxidant properties in the brain, so their decrease can lead to neuronal death, as occurs in dopaminergic neurons in PD and other neurodegenerative processes (Mosley et al. 2006). Therefore, metabolites of TSP can potentially predict the development and progression of PD, and can be proposed as predictive biomarkers.

Despite the increased knowledge about the molecular mechanisms of the TSP and its relationship with PD, it is crucial to consider that it is only a tiny part of the extensive network of interconnected pathways. Additionally, more in vivo, and in vitro studies are needed to elucidate the connection between TSP and other more complex pathways involved in PD to propose possible targets and biomarkers against dopaminergic neuronal damage.


Corresponding authors: Gabriela Figueroa-González, Laboratorio de Farmacogenética, Unidad Multidisciplinaria de Investigación Experimental Zaragoza, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, 09230 Mexico City, Mexico, E-mail: ; and Daniela Silva-Adaya, Laboratorio Experimental de Enfermedades Neurodegenerativas, Instituto Nacional de Neurología y Neurocirugía, Mexico, 14269, Mexico, E-mail:

Funding source: PAPIIT

Award Identifier / Grant number: IA208422 and IT-200323

Acknowledgments

This study was performed in partial fulfillment of the requirements for the Biology degree of Corona-Trejo A. in the Facultad de Estudios Superiores Zaragoza at the Universidad Nacional Autónoma de México. The authors want to thank Dr. P. Petrosyan for his important comments. All of the figures in this manuscript were created using BioRender.com

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: We thank PAPIIT-IA208422 and PAPIIT IT-200323 for academic and financial support. Villegas-Vázquez E. Y. received a Postdoctoral Fellowship from DGAPA-UNAM.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.

References

Abe, K. and Kimura, H. (1996). The possible role of hydrogen sulfide as an endogenous neuromodulator. J. Neurosci. 16: 1066–1071, https://doi.org/10.1523/jneurosci.16-03-01066.1996.Search in Google Scholar PubMed PubMed Central

Ai, S.X., Xu, Q., Hu, Y.C., Song, C.Y., Guo, J.F., Shen, L., Wang, C.R., Yu, R.L., Yan, X.X., and Tang, B.S. (2014). Hypomethylation of SNCA in blood of patients with sporadic Parkinson’s disease. J. Neurol. Sci. 337: 123–128, https://doi.org/10.1016/j.jns.2013.11.033.Search in Google Scholar PubMed

Al Mutairi, F. (2020). Hyperhomocysteinemia: clinical insights. J. Cent. Nerv. Syst. Dis. 12: 1179573520962230, https://doi.org/10.1177/1179573520962230.Search in Google Scholar PubMed PubMed Central

Allain, P., Le Bouil, A., Cordillet, E., Le Quay, L., Bagheri, H., and Montastruc, J.L. (1995). Sulfate and cysteine levels in the plasma of patients with Parkinson’s disease. Neurotoxicology 16: 527–529.Search in Google Scholar

Andersen, J.K. (2001). Do alterations in glutathione and iron levels contribute to pathology associated with Parkinson’s disease? Novartis Found. Symp. 235: 11–20.10.1002/0470868694.ch3Search in Google Scholar

Aoyama, K (2021). Glutathione in the brain. Int. J. Mol. Sci. 22: 5010, https://doi.org/10.3390/ijms22095010.Search in Google Scholar PubMed PubMed Central

Araki, K., Takino, T., Ida, S., and Kuriyama, K. (1986). Alteration of amino acids in cerebrospinal fluid from patients with Parkinson’s disease and spinocerebellar degeneration. Acta Neurol. Scand. 73: 105–110, https://doi.org/10.1111/j.1600-0404.1986.tb03249.x.Search in Google Scholar PubMed

Armstrong, M.J. and Okun, M.S. (2020). Diagnosis and treatment of Parkinson disease: a review. J. Am. Med. Assoc. 323: 548–560, https://doi.org/10.1001/jama.2019.22360.Search in Google Scholar PubMed

Asanuma, M. and Miyazaki, I. (2021). Glutathione and related molecules in Parkinsonism. Int. J. Mol. Sci. 22: 8689, https://doi.org/10.3390/ijms22168689.Search in Google Scholar PubMed PubMed Central

Augsburger, F. and Szabo, C. (2020). Potential role of the 3-mercaptopyruvate sulfurtransferase (3-MST)-hydrogen sulfide (H2S) pathway in cancer cells. Pharmacol. Res. 154: 104083, https://doi.org/10.1016/j.phrs.2018.11.034.Search in Google Scholar PubMed

Bae, S.K., Heo, C.H., Choi, D.J., Sen, D., Joe, E.H., Cho, B.R., and Kim, H.M. (2013). A ratiometric two-photon fluorescent probe reveals reduction in mitochondrial H2S production in Parkinson’s disease gene knockout astrocytes. J. Am. Chem. Soc. 135: 9915–9923, https://doi.org/10.1021/ja404004v.Search in Google Scholar PubMed

Bakeberg, M.C., Jefferson, A., Riley, M., Byrnes, M., Ghosh, S., Mastaglia, F.L., Horne, M.K., McGregor, S., Stell, R., Kenna, J., et al.. (2019). Elevated serum homocysteine levels have differential gender-specific associations with motor and cognitive states in Parkinson’s disease. Parkinsons Dis. 2019: 3124295, https://doi.org/10.1155/2019/3124295.Search in Google Scholar PubMed PubMed Central

Baliou, S., Adamaki, M., Ioannou, P., Pappa, A., Panayiotidis, M.I., Spandidos, D.A., Christodoulou, I., Kyriakopoulos, A.M., and Zoumpourlis, V. (2021). Protective role of taurine against oxidative stress. Mol. Med. Rep. 24: 605, https://doi.org/10.3892/mmr.2021.12242.Search in Google Scholar PubMed PubMed Central

Beard, R.S.Jr., Reynolds, J.J., and Bearden, S.E. (2011). Hyperhomocysteinemia increases permeability of the blood-brain barrier by NMDA receptor-dependent regulation of adherens and tight junctions. Blood 118: 2007–2014, https://doi.org/10.1182/blood-2011-02-338269.Search in Google Scholar PubMed PubMed Central

Ben-Shlomo, Y. and Marmot, M.G. (1995). Survival and cause of death in a cohort of patients with parkinsonism: possible clues to aetiology? J. Neurol. Neurosurg. Psychiatry. 58: 293–299, https://doi.org/10.1136/jnnp.58.3.293.Search in Google Scholar PubMed PubMed Central

Bianchi, L., Colivicchi, M.A., Bolam, J.P., and Della Corte, L. (1998). The release of amino acids from rat neostriatum and substantia nigra in vivo: a dual microdialysis probe analysis. Neuroscience 87: 171–180, https://doi.org/10.1016/s0306-4522(98)00090-6.Search in Google Scholar PubMed

Bjorklund, G., Peana, M., Maes, M., Dadar, M., and Severin, B. (2021). The glutathione system in Parkinson’s disease and its progression. Neurosci. Biobehav. Rev. 120: 470–478, https://doi.org/10.1016/j.neubiorev.2020.10.004.Search in Google Scholar PubMed

Bjorklund, G., Stejskal, V., Urbina, M.A., Dadar, M., Chirumbolo, S., and Mutter, J. (2018). Metals and Parkinson’s disease: mechanisms and biochemical processes. Curr. Med. Chem. 25: 2198–2214, https://doi.org/10.2174/0929867325666171129124616.Search in Google Scholar PubMed

Boushey, C.J., Beresford, S.A., Omenn, G.S., and Motulsky, A.G. (1995). A quantitative assessment of plasma homocysteine as a risk factor for vascular disease. Probable benefits of increasing folic acid intakes. J. Am. Med. Assoc. 274: 1049–1057, https://doi.org/10.1001/jama.274.13.1049.Search in Google Scholar

Brosnan, J.T., Jacobs, R.L., Stead, L.M., and Brosnan, M.E. (2004). Methylation demand: a key determinant of homocysteine metabolism. Acta Biochim. Pol. 51: 405–413, https://doi.org/10.18388/abp.2004_3580.Search in Google Scholar

Calne, D.B. (1993). Treatment of Parkinson’s disease. N. Engl. J. Med. 329: 1021–1027, https://doi.org/10.1056/nejm199309303291408.Search in Google Scholar

Cao, X., Cao, L., Ding, L., and Bian, J.S. (2018). A new hope for a devastating disease: hydrogen sulfide in Parkinson’s disease. Mol. Neurobiol. 55: 3789–3799, https://doi.org/10.1007/s12035-017-0617-0.Search in Google Scholar PubMed

Che, Y., Hou, L., Sun, F., Zhang, C., Liu, X., Piao, F., Zhang, D., Li, H., and Wang, Q. (2018). Taurine protects dopaminergic neurons in a mouse Parkinson’s disease model through inhibition of microglial M1 polarization. Cell Death Dis. 9: 435, https://doi.org/10.1038/s41419-018-0468-2.Search in Google Scholar PubMed PubMed Central

Chen, C., Xia, S., He, J., Lu, G., Xie, Z., and Han, H. (2019). Roles of taurine in cognitive function of physiology, pathologies and toxication. Life Sci. 231: 116584, https://doi.org/10.1016/j.lfs.2019.116584.Search in Google Scholar PubMed

Chen, W.L., Niu, Y.Y., Jiang, W.Z., Tang, H.L., Zhang, C., Xia, Q.M., and Tang, X.Q. (2015). Neuroprotective effects of hydrogen sulfide and the underlying signaling pathways. Rev. Neurosci. 26: 129–142, https://doi.org/10.1515/revneuro-2014-0051.Search in Google Scholar PubMed

Cheng, H., Gomes-Trolin, C., Aquilonius, S.M., Steinberg, A., Lofberg, C., Ekblom, J., and Oreland, L. (1997). Levels of L-methionine S-adenosyltransferase activity in erythrocytes and concentrations of S-adenosylmethionine and S-adenosylhomocysteine in whole blood of patients with Parkinson’s disease. Exp. Neurol. 145: 580–585, https://doi.org/10.1006/exnr.1997.6466.Search in Google Scholar PubMed

Chung, K.K., Thomas, B., Li, X., Pletnikova, O., Troncoso, J.C., Marsh, L., Dawson, V.L., and Dawson, T.M. (2004). S-nitrosylation of parkin regulates ubiquitination and compromises parkin’s protective function. Science 304: 1328–1331, https://doi.org/10.1126/science.1093891.Search in Google Scholar PubMed

Commandeur, J.N., Stijntjes, G.J., and Vermeulen, N.P. (1995). Enzymes and transport systems involved in the formation and disposition of glutathione S-conjugates. Role in bioactivation and detoxication mechanisms of xenobiotics. Pharmacol. Rev. 47: 271–330.Search in Google Scholar

Danielson, S.R. and Andersen, J.K. (2008). Oxidative and nitrative protein modifications in Parkinson’s disease. Free Radic. Biol. Med. 44: 1787–1794, https://doi.org/10.1016/j.freeradbiomed.2008.03.005.Search in Google Scholar PubMed PubMed Central

Dawson, R.Jr., Baker, D., Eppler, B., Tang, E., Shih, D., Hern, H., and Hu, M. (2000). Taurine inhibition of metal-stimulated catecholamine oxidation. Neurotox. Res. 2: 1–15, https://doi.org/10.1007/bf03033322.Search in Google Scholar

Dawson, R.Jr., Pelleymounter, M.A., Cullen, M.J., Gollub, M., and Liu, S. (1999). An age-related decline in striatal taurine is correlated with a loss of dopaminergic markers. Brain Res. Bull. 48: 319–324, https://doi.org/10.1016/s0361-9230(99)00003-9.Search in Google Scholar PubMed

Diao, H.M., Song, Z.F., and Xu, H.D. (2019). Association between MTHFR genetic polymorphism and Parkinson’s disease susceptibility: a meta-analysis. Open Med. 14: 613–624, https://doi.org/10.1515/med-2019-0069.Search in Google Scholar PubMed PubMed Central

Dias, V., Junn, E., and Mouradian, M.M. (2013). The role of oxidative stress in Parkinson’s disease. J. Parkinsons Dis. 3: 461–491, https://doi.org/10.3233/jpd-130230.Search in Google Scholar PubMed PubMed Central

Dickson, D.W. (2018). Neuropathology of Parkinson disease. Parkinsonism Relat. Disord. 46: S30–S33, https://doi.org/10.1016/j.parkreldis.2017.07.033.Search in Google Scholar PubMed PubMed Central

Diwakar, L. and Ravindranath, V. (2007). Inhibition of cystathionine-gamma-lyase leads to loss of glutathione and aggravation of mitochondrial dysfunction mediated by excitatory amino acid in the CNS. Neurochem. Int. 50: 418–426, https://doi.org/10.1016/j.neuint.2006.09.014.Search in Google Scholar PubMed

Djuric, D., Jakovljevic, V., Zivkovic, V., and Srejovic, I. (2018). Homocysteine and homocysteine-related compounds: an overview of the roles in the pathology of the cardiovascular and nervous systems. Can. J. Physiol. Pharmacol. 96: 991–1003, https://doi.org/10.1139/cjpp-2018-0112.Search in Google Scholar PubMed

Dominy, J., Eller, S., and Dawson, R.Jr. (2004). Building biosynthetic schools: reviewing compartmentation of CNS taurine synthesis. Neurochem. Res. 29: 97–103, https://doi.org/10.1023/b:nere.0000010437.81860.d5.10.1023/B:NERE.0000010437.81860.d5Search in Google Scholar

Dominy, J.E.Jr., Hirschberger, L.L., Coloso, R.M., and Stipanuk, M.H. (2006). Regulation of cysteine dioxygenase degradation is mediated by intracellular cysteine levels and the ubiquitin-26 S proteasome system in the living rat. Biochem. J. 394: 267–273, https://doi.org/10.1042/bj20051510.Search in Google Scholar

Dominy, J.E.Jr., Simmons, C.R., Hirschberger, L.L., Hwang, J., Coloso, R.M., and Stipanuk, M.H. (2007). Discovery and characterization of a second mammalian thiol dioxygenase, cysteamine dioxygenase. J. Biol. Chem. 282: 25189–25198, https://doi.org/10.1074/jbc.m703089200.Search in Google Scholar PubMed

Dorszewska, J., Florczak, J., Rozycka, A., Kempisty, B., Jaroszewska-Kolecka, J., Chojnacka, K., Trzeciak, W.H., and Kozubski, W. (2007). Oxidative DNA damage and level of thiols as related to polymorphisms of MTHFR, MTR, MTHFD1 in Alzheimer’s and Parkinson’s diseases. Acta Neurobiol. Exp. 67: 113–129.Search in Google Scholar

dos Santos, E.F., Busanello, E.N., Miglioranza, A., Zanatta, A., Barchak, A.G., Vargas, C.R., Saute, J., Rosa, C., Carrion, M.J., Camargo, D., et al.. (2009). Evidence that folic acid deficiency is a major determinant of hyperhomocysteinemia in Parkinson’s disease. Metab. Brain Dis. 24: 257–269, https://doi.org/10.1007/s11011-009-9139-4.Search in Google Scholar PubMed

Dray, A. and Straughan, D.W. (1976). Synaptic mechanisms in the substantia nigra. J. Pharm. Pharmacol. 28: 400–405, https://doi.org/10.1111/j.2042-7158.1976.tb04187.x.Search in Google Scholar PubMed

Dringen, R. (2000). Metabolism and functions of glutathione in brain. Prog. Neurobiol. 62: 649–671, https://doi.org/10.1016/s0301-0082(99)00060-x.Search in Google Scholar PubMed

Dringen, R., Gutterer, J.M., and Hirrlinger, J. (2000). Glutathione metabolism in brain metabolic interaction between astrocytes and neurons in the defense against reactive oxygen species. Eur. J. Biochem. 267: 4912–4916, https://doi.org/10.1046/j.1432-1327.2000.01597.x.Search in Google Scholar PubMed

Dringen, R. and Hirrlinger, J. (2003). Glutathione pathways in the brain. Biol. Chem. 384: 505–516, https://doi.org/10.1515/bc.2003.059.Search in Google Scholar

Du, C., Jin, M., Hong, Y., Li, Q., Wang, X.H., Xu, J.M., Wang, F., Zhang, Y., Jia, J., Liu, C.F., et al.. (2014). Downregulation of cystathionine beta-synthase/hydrogen sulfide contributes to rotenone-induced microglia polarization toward M1 type. Biochem. Biophys. Res. Commun. 451: 239–245, https://doi.org/10.1016/j.bbrc.2014.07.107.Search in Google Scholar PubMed

Duan, W., Ladenheim, B., Cutler, R.G., KrumanII, Cadet, J.L., and Mattson, M.P. (2002). Dietary folate deficiency and elevated homocysteine levels endanger dopaminergic neurons in models of Parkinson’s disease. J. Neurochem. 80: 101–110, https://doi.org/10.1046/j.0022-3042.2001.00676.x.Search in Google Scholar PubMed

El Idrissi, A. (2019). Taurine regulation of neuroendocrine function. Adv. Exp. Med. Biol. 1155: 977–985, https://doi.org/10.1007/978-981-13-8023-5_81.Search in Google Scholar PubMed

Engelborghs, S., Marescau, B., and De Deyn, P.P. (2003). Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson’s disease. Neurochem. Res. 28: 1145–1150, https://doi.org/10.1023/a:1024255208563.10.1023/A:1024255208563Search in Google Scholar PubMed

Ericson, M., Chau, P., Adermark, L., and Soderpalm, B. (2013). Rising taurine and ethanol concentrations in nucleus accumbens interact to produce the dopamine-activating effects of alcohol. Adv. Exp. Med. Biol. 775: 215–223, https://doi.org/10.1007/978-1-4614-6130-2_18.Search in Google Scholar PubMed

Fan, X., Zhang, L., Li, H., Chen, G., Qi, G., Ma, X., and Jin, Y. (2020). Role of homocysteine in the development and progression of Parkinson’s disease. Ann. Clin. Transl. Neurol. 7: 2332–2338, https://doi.org/10.1002/acn3.51227.Search in Google Scholar PubMed PubMed Central

Filipovic, M.R. (2015). Persulfidation (S-sulfhydration) and H2S. Handb. Exp. Pharmacol. 230: 29–59, https://doi.org/10.1007/978-3-319-18144-8_2.Search in Google Scholar PubMed

Fiser, B., Jojart, B., Csizmadia, I.G., and Viskolcz, B. (2013). Glutathione - hydroxyl radical interaction: a theoretical study on radical recognition process. PLoS One 8: e73652, https://doi.org/10.1371/journal.pone.0073652.Search in Google Scholar PubMed PubMed Central

Fong, C.S., Shyu, H.Y., Shieh, J.C., Fu, Y.P., Chin, T.Y., Wang, H.W., and Cheng, C.W. (2011). Association of MTHFR, MTR, and MTRR polymorphisms with Parkinson’s disease among ethnic Chinese in Taiwan. Clin. Chim. Acta 412: 332–338, https://doi.org/10.1016/j.cca.2010.11.004.Search in Google Scholar PubMed

Franco, R., Schoneveld, O.J., Pappa, A., and Panayiotidis, M.I. (2007). The central role of glutathione in the pathophysiology of human diseases. Arch. Physiol. Biochem. 113: 234–258, https://doi.org/10.1080/13813450701661198.Search in Google Scholar PubMed

Galvan, I., Ghanem, G., and Moller, A.P. (2012). Has removal of excess cysteine led to the evolution of pheomelanin? Pheomelanogenesis as an excretory mechanism for cysteine. Bioessays 34: 565–568, https://doi.org/10.1002/bies.201200017.Search in Google Scholar PubMed

Garcia, S., Cano-Martinez, L.J., Coral-Vazquez, R.M., Coronel-Perez, A., Gomez-Diaz, B., Toledo-Lozano, C.G., Gallegos-Arreola, M.P., Davila-Maldonado, L., Jimenez-Hernandez, D.A., Alcaraz-Estrada, S.L., et al.. (2017). Analysis of the rs13306560 functional variant in the promoter region of the MTHFR gene in sporadic Parkinson s disease. Neuro. Endocrinol. Lett. 38: 257–260.Search in Google Scholar

Garcia, S., Coral-Vazquez, R., Gallegos-Arreola, M.P., Montes-Almanza, L.A., Canto, P., Garcia-Martinez, F.A., Chavira-Hernandez, G., Palma-Flores, C., Davila-Maldonado, L., Cuevas-Garcia, C.F., et al.. (2015). Association of the rs1801133 variant in the MTHFR gene and sporadic Parkinson’s disease. Folia Neuropathol. 53: 24–28, https://doi.org/10.5114/fn.2015.49971.Search in Google Scholar PubMed

Ghezzi, P. (2011). Role of glutathione in immunity and inflammation in the lung. Int. J. Gen. Med. 4: 105–113, https://doi.org/10.2147/ijgm.s15618.Search in Google Scholar

Gokce Cokal, B., Yurtdas, M., Keskin Guler, S., Gunes, H.N., Atac Ucar, C., Aytac, B., Durak, Z.E., Yoldas, T.K., Durak, I., and Cubukcu, H.C. (2017). Serum glutathione peroxidase, xanthine oxidase, and superoxide dismutase activities and malondialdehyde levels in patients with Parkinson’s disease. Neurol. Sci. 38: 425–431, https://doi.org/10.1007/s10072-016-2782-8.Search in Google Scholar PubMed

Griffith, O.W., Bridges, R.J., and Meister, A. (1979). Transport of gamma-glutamyl amino acids: role of glutathione and gamma-glutamyl transpeptidase. Proc. Natl. Acad. Sci. U. S. A. 76: 6319–6322, https://doi.org/10.1073/pnas.76.12.6319.Search in Google Scholar PubMed PubMed Central

Hauser, D.N. and Hastings, T.G. (2013). Mitochondrial dysfunction and oxidative stress in Parkinson’s disease and monogenic parkinsonism. Neurobiol. Dis. 51: 35–42, https://doi.org/10.1016/j.nbd.2012.10.011.Search in Google Scholar PubMed PubMed Central

He, K., Merchant, A., Rimm, E.B., Rosner, B.A., Stampfer, M.J., Willett, W.C., and Ascherio, A. (2004). Folate, vitamin B6, and B12 intakes in relation to risk of stroke among men. Stroke 35: 169–174, https://doi.org/10.1161/01.str.0000106762.55994.86.Search in Google Scholar

Heafield, M.T., Fearn, S., Steventon, G.B., Waring, R.H., Williams, A.C., and Sturman, S.G. (1990). Plasma cysteine and sulphate levels in patients with motor neurone, Parkinson’s and Alzheimer’s disease. Neurosci. Lett. 110: 216–220, https://doi.org/10.1016/0304-3940(90)90814-p.Search in Google Scholar PubMed

Henchcliffe, C. and Beal, M.F. (2008). Mitochondrial biology and oxidative stress in Parkinson disease pathogenesis. Nat. Clin. Pract. Neurol. 4: 600–609, https://doi.org/10.1038/ncpneuro0924.Search in Google Scholar PubMed

Hensley, K. and Denton, T.T. (2015). Alternative functions of the brain transsulfuration pathway represent an underappreciated aspect of brain redox biochemistry with significant potential for therapeutic engagement. Free Radic. Biol. Med. 78: 123–134, https://doi.org/10.1016/j.freeradbiomed.2014.10.581.Search in Google Scholar PubMed PubMed Central

Hertel, J., Harms, A.C., Heinken, A., Baldini, F., Thinnes, C.C., Glaab, E., Vasco, D.A., Pietzner, M., Stewart, I.D., Wareham, N.J., et al.. (2019). Integrated analyses of microbiome and longitudinal metabolome data reveal microbial-host interactions on sulfur metabolism in Parkinson’s disease. Cell. Rep. 29: 1767–1777 e1768, https://doi.org/10.1016/j.celrep.2019.10.035.Search in Google Scholar PubMed PubMed Central

Hoffman, D.R., Cornatzer, W.E., and Duerre, J.A. (1979). Relationship between tissue levels of S-adenosylmethionine, S-adenylhomocysteine, and transmethylation reactions. Can. J. Biochem. 57: 56–65, https://doi.org/10.1139/o79-007.Search in Google Scholar PubMed

Hou, L., Che, Y., Sun, F., and Wang, Q. (2018). Taurine protects noradrenergic locus coeruleus neurons in a mouse Parkinson’s disease model by inhibiting microglial M1 polarization. Amino Acids 50: 547–556, https://doi.org/10.1007/s00726-018-2547-1.Search in Google Scholar PubMed

Hou, X., Yuan, Y., Sheng, Y., Yuan, B., Wang, Y., Zheng, J., Liu, C.F., Zhang, X., and Hu, L.F. (2017). GYY4137, an H2S slow-releasing donor, prevents nitrative stress and alpha-synuclein nitration in an MPTP mouse model of Parkinson’s disease. Front. Pharmacol. 8: 741, https://doi.org/10.3389/fphar.2017.00741.Search in Google Scholar PubMed PubMed Central

Hu, L.F., Lu, M., Tiong, C.X., Dawe, G.S., Hu, G., and Bian, J.S. (2010). Neuroprotective effects of hydrogen sulfide on Parkinson’s disease rat models. Aging Cell 9: 135–146, https://doi.org/10.1111/j.1474-9726.2009.00543.x.Search in Google Scholar PubMed

Hu, L.F., Lu, M., Wu, Z.Y., Wong, P.T., and Bian, J.S. (2009). Hydrogen sulfide inhibits rotenone-induced apoptosis via preservation of mitochondrial function. Mol. Pharmacol. 75: 27–34, https://doi.org/10.1124/mol.108.047985.Search in Google Scholar PubMed

Iskusnykh, I.Y., Zakharova, A.A., and Pathak, D. (2022). Glutathione in brain disorders and aging. Molecules 27: 324.10.3390/molecules27010324Search in Google Scholar PubMed PubMed Central

Isobe, C., Murata, T., Sato, C., and Terayama, Y. (2005). Increase of total homocysteine concentration in cerebrospinal fluid in patients with Alzheimer’s disease and Parkinson’s disease. Life Sci. 77: 1836–1843, https://doi.org/10.1016/j.lfs.2005.02.014.Search in Google Scholar PubMed

Ito, T., Yoshikawa, N., Inui, T., Miyazaki, N., Schaffer, S.W., and Azuma, J. (2014). Tissue depletion of taurine accelerates skeletal muscle senescence and leads to early death in mice. PLoS One 9: e107409, https://doi.org/10.1371/journal.pone.0107409.Search in Google Scholar PubMed PubMed Central

Jakaria, M., Azam, S., Haque, M.E., Jo, S.H., Uddin, M.S., Kim, I.S., and Choi, D.K. (2019). Taurine and its analogs in neurological disorders: focus on therapeutic potential and molecular mechanisms. Redox Biol. 24: 101223, https://doi.org/10.1016/j.redox.2019.101223.Search in Google Scholar PubMed PubMed Central

Jakubowski, H. (2000). Calcium-dependent human serum homocysteine thiolactone hydrolase. A protective mechanism against protein N-homocysteinylation. J. Biol. Chem. 275: 3957–3962, https://doi.org/10.1074/jbc.275.6.3957.Search in Google Scholar PubMed

Jameson, G.N.L. (2011). Iron, cysteine and Parkinson’s disease. Monatsh. Chem. 142: 325–329, https://doi.org/10.1007/s00706-011-0475-9.Search in Google Scholar

Janaky, R., Varga, V., Hermann, A., Saransaari, P., and Oja, S.S. (2000). Mechanisms of L-cysteine neurotoxicity. Neurochem. Res. 25: 1397–1405, https://doi.org/10.1023/a:1007616817499.10.1023/A:1007616817499Search in Google Scholar

Jankovic, J. and Tan, E.K. (2020). Parkinson’s disease: etiopathogenesis and treatment. J. Neurol Neurosurg. Psychiatr. 91: 795–808, https://doi.org/10.1136/jnnp-2019-322338.Search in Google Scholar PubMed

Jellinger, K.A. (1999). The role of iron in neurodegeneration: prospects for pharmacotherapy of Parkinson’s disease. Drugs Aging 14: 115–140, https://doi.org/10.2165/00002512-199914020-00004.Search in Google Scholar PubMed

Jowaed, A., Schmitt, I., Kaut, O., and Wullner, U. (2010). Methylation regulates alpha-synuclein expression and is decreased in Parkinson’s disease patients’ brains. J. Neurosci. 30: 6355–6359, https://doi.org/10.1523/jneurosci.6119-09.2010.Search in Google Scholar

Kalecky, K., Ashcraft, P., and Bottiglieri, T. (2022). One-carbon metabolism in Alzheimer’s disease and Parkinson’s disease brain tissue. Nutrients 14: 599, https://doi.org/10.3390/nu14030599.Search in Google Scholar PubMed PubMed Central

Kamat, P.K., Kyles, P., Kalani, A., and Tyagi, N. (2016). Hydrogen sulfide ameliorates homocysteine-Induced Alzheimer’s disease-like pathology, blood-brain barrier disruption, and synaptic disorder. Mol. Neurobiol. 53: 2451–2467, https://doi.org/10.1007/s12035-015-9212-4.Search in Google Scholar PubMed PubMed Central

Kayadibi, H., Sertoglu, E., and Uyanik, M. (2014). Important issues in studies dealing with total homocysteine. Transplantation 98: e89, https://doi.org/10.1097/tp.0000000000000492.Search in Google Scholar

Kida, K. and Ichinose, F. (2015). Hydrogen sulfide and neuroinflammation. Handb. Exp. Pharmacol. 230: 181–189, https://doi.org/10.1007/978-3-319-18144-8_9.Search in Google Scholar PubMed

Kida, K., Yamada, M., Tokuda, K., Marutani, E., Kakinohana, M., Kaneki, M., and Ichinose, F. (2011). Inhaled hydrogen sulfide prevents neurodegeneration and movement disorder in a mouse model of Parkinson’s disease. Antioxid. Redox Signaling 15: 343–352, https://doi.org/10.1089/ars.2010.3671.Search in Google Scholar PubMed PubMed Central

Kim, W.Y., Kim, H., Hong, J.B., Sheen, S.H., Han, I.B., and Sohn, S. (2021). Association of Parkinson’s disease with ischemic stroke in Korea: a nationwide longitudinal cohort study in Korea. J. Cerebrovasc. Endovasc. Neurosurg. 23: 233–239, https://doi.org/10.7461/jcen.2021.e2021.03.007.Search in Google Scholar

Kimura, Y., Goto, Y., and Kimura, H. (2010). Hydrogen sulfide increases glutathione production and suppresses oxidative stress in mitochondria. Antioxid. Redox Signaling 12: 1–13, https://doi.org/10.1089/ars.2008.2282.Search in Google Scholar PubMed

Kimura, Y., Toyofuku, Y., Koike, S., Shibuya, N., Nagahara, N., Lefer, D., Ogasawara, Y., and Kimura, H. (2015). Identification of H2S3 and H2S produced by 3-mercaptopyruvate sulfurtransferase in the brain. Sci. Rep. 5: 14774, https://doi.org/10.1038/srep14774.Search in Google Scholar PubMed PubMed Central

Koga, M., Serritella, A.V., Messmer, M.M., Hayashi-Takagi, A., Hester, L.D., Snyder, S.H., Sawa, A., and Sedlak, T.W. (2011). Glutathione is a physiologic reservoir of neuronal glutamate. Biochem. Biophys. Res. Commun. 409: 596–602, https://doi.org/10.1016/j.bbrc.2011.04.087.Search in Google Scholar PubMed PubMed Central

KrumanII, Culmsee, C., Chan, S.L., Kruman, Y., Guo, Z., Penix, L., and Mattson, M.P. (2000). Homocysteine elicits a DNA damage response in neurons that promotes apoptosis and hypersensitivity to excitotoxicity. J. Neurosci. 20: 6920–6926, https://doi.org/10.1523/jneurosci.20-18-06920.2000.Search in Google Scholar

Kuhn, D.M., Arthur, R.E.Jr., Thomas, D.M., and Elferink, L.A. (1999). Tyrosine hydroxylase is inactivated by catechol-quinones and converted to a redox-cycling quinoprotein: possible relevance to Parkinson’s disease. J. Neurochem. 73: 1309–1317, https://doi.org/10.1046/j.1471-4159.1999.0731309.x.Search in Google Scholar PubMed

Kuhn, W., Roebroek, R., Blom, H., van Oppenraaij, D., Przuntek, H., Kretschmer, A., Buttner, T., Woitalla, D., and Muller, T. (1998). Elevated plasma levels of homocysteine in Parkinson’s disease. Eur. Neurol. 40: 225–227, https://doi.org/10.1159/000007984.Search in Google Scholar PubMed

Kumar, M., Ray, R.S., and Sandhir, R. (2018). Hydrogen sulfide attenuates homocysteine-induced neurotoxicity by preventing mitochondrial dysfunctions and oxidative damage: in vitro and in vivo studies. Neurochem. Int. 120: 87–98, https://doi.org/10.1016/j.neuint.2018.07.010.Search in Google Scholar PubMed

Lamberti, P., Zoccolella, S., Armenise, E., Lamberti, S.V., Fraddosio, A., de Mari, M., Iliceto, G., and Livrea, P. (2005a). Hyperhomocysteinemia in L-dopa treated Parkinson’s disease patients: effect of cobalamin and folate administration. Eur. Neurol. J. 12: 365–368, https://doi.org/10.1111/j.1468-1331.2004.00973.x.Search in Google Scholar PubMed

Lamberti, P., Zoccolella, S., Iliceto, G., Armenise, E., Fraddosio, A., de Mari, M., and Livrea, P. (2005b). Effects of levodopa and COMT inhibitors on plasma homocysteine in Parkinson’s disease patients. Mov. Disord. 20: 69–72, https://doi.org/10.1002/mds.20261.Search in Google Scholar PubMed

LaVoie, M.J., Ostaszewski, B.L., Weihofen, A., Schlossmacher, M.G., and Selkoe, D.J. (2005). Dopamine covalently modifies and functionally inactivates parkin. Nat. Med. 11: 1214–1221, https://doi.org/10.1038/nm1314.Search in Google Scholar PubMed

Lee, E.S., Chen, H., Soliman, K.F., and Charlton, C.G. (2005). Effects of homocysteine on the dopaminergic system and behavior in rodents. Neurotoxicology 26: 361–371, https://doi.org/10.1016/j.neuro.2005.01.008.Search in Google Scholar PubMed

Leon, R., Wu, H., Jin, Y., Wei, J., Buddhala, C., Prentice, H., and Wu, J.Y. (2009). Protective function of taurine in glutamate-induced apoptosis in cultured neurons. J. Neurosci. Res. 87: 1185–1194, https://doi.org/10.1002/jnr.21926.Search in Google Scholar PubMed

Li, H. and Dryhurst, G. (1997). Irreversible inhibition of mitochondrial complex I by 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxyli c acid (DHBT-1): a putative nigral endotoxin of relevance to Parkinson’s disease. J. Neurochem. 69: 1530–1541, https://doi.org/10.1046/j.1471-4159.1997.69041530.x.Search in Google Scholar PubMed

Li, W.J., Jiang, H., Song, N., and Xie, J.X. (2010). Dose- and time-dependent alpha-synuclein aggregation induced by ferric iron in SK-N-SH cells. Neurosci. Bull. 26: 205–210, https://doi.org/10.1007/s12264-010-1117-7.Search in Google Scholar PubMed PubMed Central

Li, J., Gu, C., Zhu, M., Li, D., Chen, L., and Zhu, X. (2020). Correlations between blood lipid, serum cystatin C, and homocysteine levels in patients with Parkinson’s disease. Psychogeriatrics 20: 180–188, https://doi.org/10.1111/psyg.12483.Search in Google Scholar PubMed

Licking, N., Murchison, C., Cholerton, B., Zabetian, C.P., Hu, S.C., Montine, T.J., Peterson-Hiller, A.L., Chung, K.A., Edwards, K., Leverenz, J.B., et al.. (2017). Homocysteine and cognitive function in Parkinson’s disease. Parkinsonism Relat. Disorders 44: 1–5, https://doi.org/10.1016/j.parkreldis.2017.08.005.Search in Google Scholar PubMed PubMed Central

Liddell, J.R. and White, A.R. (2018). Nexus between mitochondrial function, iron, copper and glutathione in Parkinson’s disease. Neurochem. Int. 117: 126–138, https://doi.org/10.1016/j.neuint.2017.05.016.Search in Google Scholar PubMed

Lin, H.C., Yang, C.M., Liu, C.L., and Hu, M.L. (2008). Synergistic effects of homocysteine, S-adenosylhomocysteine and adenosine on apoptosis in BV-2 murine microglial cells. Biofactors 34: 81–95, https://doi.org/10.1002/biof.5520340201.Search in Google Scholar PubMed

Lin, J.Y., Ho, T.J., Tsai, B.C., Chiang, C.Y., Kao, H.C., Kuo, W.W., Chen, R.J., Viswanadha, V.P., Huang, C.W., and Huang, C.Y. (2021). Exercise renovates H2S and Nrf2-related antioxidant pathways to suppress apoptosis in the natural ageing process of male rat cortex. Biogerontology 22: 495–506, https://doi.org/10.1007/s10522-021-09929-8.Search in Google Scholar PubMed

Lionaki, E., Ploumi, C., and Tavernarakis, N. (2022). One-carbon metabolism: pulling the strings behind aging and neurodegeneration. Cells 11: 214.10.3390/cells11020214Search in Google Scholar PubMed PubMed Central

Liu, Y., Liao, S., Quan, H., Lin, Y., Li, J., and Yang, Q. (2016). Involvement of microRNA-135a-5p in the protective effects of hydrogen sulfide against Parkinson’s disease. Cell. Physiol. Biochem. 40: 18–26, https://doi.org/10.1159/000452521.Search in Google Scholar PubMed

Longoni, A., Bellaver, B., Bobermin, L.D., Santos, C.L., Nonose, Y., Kolling, J., Dos Santos, T.M., de Assis, A.M., Quincozes-Santos, A., and Wyse, A.T.S. (2018). Homocysteine induces glial reactivity in adult rat astrocyte cultures. Mol. Neurobiol. 55: 1966–1976, https://doi.org/10.1007/s12035-017-0463-0.Search in Google Scholar PubMed

Lu, M., Zhao, F.F., Tang, J.J., Su, C.J., Fan, Y., Ding, J.H., Bian, J.S., and Hu, G. (2012). The neuroprotection of hydrogen sulfide against MPTP-induced dopaminergic neuron degeneration involves uncoupling protein 2 rather than ATP-sensitive potassium channels. Antioxid. Redox Signaling 17: 849–859, https://doi.org/10.1089/ars.2011.4507.Search in Google Scholar PubMed PubMed Central

Mandal, P.K., Seiler, A., Perisic, T., Kolle, P., Banjac Canak, A., Forster, H., Weiss, N., Kremmer, E., Lieberman, M.W., Bannai, S., et al.. (2010). System x(c)- and thioredoxin reductase 1 cooperatively rescue glutathione deficiency. J. Biol. Chem. 285: 22244–22253, https://doi.org/10.1074/jbc.m110.121327.Search in Google Scholar

Martignoni, E., Tassorelli, C., Nappi, G., Zangaglia, R., Pacchetti, C., and Blandini, F. (2007). Homocysteine and Parkinson’s disease: a dangerous liaison? J. Neurol. Sci. 257: 31–37, https://doi.org/10.1016/j.jns.2007.01.028.Search in Google Scholar PubMed

Matsumoto, L., Takuma, H., Tamaoka, A., Kurisaki, H., Date, H., Tsuji, S., and Iwata, A. (2010). CpG demethylation enhances α-synuclein expression and affects the pathogenesis of Parkinson’s disease. PLoS One 5: e15522, https://doi.org/10.1371/journal.pone.0015522.Search in Google Scholar PubMed PubMed Central

Mattson, M.P. and Shea, T.B. (2003). Folate and homocysteine metabolism in neural plasticity and neurodegenerative disorders. Trends Neurosci. 26: 137–146, https://doi.org/10.1016/s0166-2236(03)00032-8.Search in Google Scholar

McCully, K.S. (2015). Homocysteine metabolism, atherosclerosis, and diseases of aging. Compr. Physiol. 6: 471–505, https://doi.org/10.1002/cphy.c150021.Search in Google Scholar PubMed

McNaught, K.S., Olanow, C.W., Halliwell, B., Isacson, O., and Jenner, P. (2001). Failure of the ubiquitin-proteasome system in Parkinson’s disease. Nat. Rev. Neurosci. 2: 589–594, https://doi.org/10.1038/35086067.Search in Google Scholar PubMed

Menzie, J., Pan, C., Prentice, H., and Wu, J.Y. (2014). Taurine and central nervous system disorders. Amino Acids 46: 31–46, https://doi.org/10.1007/s00726-012-1382-z.Search in Google Scholar PubMed

Mersman, B., Zaidi, W., Syed, N.I., and Xu, F. (2020). Taurine promotes neurite outgrowth and synapse development of both vertebrate and invertebrate central neurons. Front. Synaptic Neurosci. 12: 29, https://doi.org/10.3389/fnsyn.2020.00029.Search in Google Scholar PubMed PubMed Central

Miles, E.W. and Kraus, J.P. (2004). Cystathionine beta-synthase: structure, function, regulation, and location of homocystinuria-causing mutations. J. Biol. Chem. 279: 29871–29874, https://doi.org/10.1074/jbc.r400005200.Search in Google Scholar

Miller, J.W., Selhub, J., Nadeau, M.R., Thomas, C.A., Feldman, R.G., and Wolf, P.A. (2003). Effect of L-dopa on plasma homocysteine in PD patients: relationship to B-vitamin status. Neurology 60: 1125–1129, https://doi.org/10.1212/01.wnl.0000055899.24594.8e.Search in Google Scholar PubMed

Miller, J.W., Shukitt-Hale, B., Villalobos-Molina, R., Nadeau, M.R., Selhub, J., and Joseph, J.A. (1997). Effect of L-Dopa and the catechol-O-methyltransferase inhibitor Ro 41-0960 on sulfur amino acid metabolites in rats. Clin. Neuropharmacol. 20: 55–66, https://doi.org/10.1097/00002826-199702000-00007.Search in Google Scholar PubMed

Molina, J.A., Jimenez-Jimenez, F.J., Gomez, P., Vargas, C., Navarro, J.A., Orti-Pareja, M., Gasalla, T., Benito-Leon, J., Bermejo, F., and Arenas, J. (1997). Decreased cerebrospinal fluid levels of neutral and basic amino acids in patients with Parkinson’s disease. J. Neurol. Sci. 150: 123–127, https://doi.org/10.1016/s0022-510x(97)00069-5.Search in Google Scholar PubMed

Montine, T.J., Picklo, M.J., Amarnath, V., Whetsell, W.O.Jr., and Graham, D.G. (1997). Neurotoxicity of endogenous cysteinylcatechols. Exp. Neurol. 148: 26–33, https://doi.org/10.1006/exnr.1997.6662.Search in Google Scholar PubMed

Morroni, F., Sita, G., Tarozzi, A., Cantelli-Forti, G., and Hrelia, P. (2014). Neuroprotection by 6-(methylsulfinyl)hexyl isothiocyanate in a 6-hydroxydopamine mouse model of Parkinson׳s disease. Brain Res. 1589: 93–104, https://doi.org/10.1016/j.brainres.2014.09.033.Search in Google Scholar PubMed

Mosley, R.L., Benner, E.J., Kadiu, I., Thomas, M., Boska, M.D., Hasan, K., Laurie, C., and Gendelman, H.E. (2006). Neuroinflammation, oxidative stress and the pathogenesis of Parkinson’s disease. Clin. Neurosci. Res. 6: 261–281, https://doi.org/10.1016/j.cnr.2006.09.006.Search in Google Scholar PubMed PubMed Central

Muller, T. and Muhlack, S. (2009). Peripheral COMT inhibition prevents levodopa associated homocysteine increase. J. Neural. Transm. 116: 1253–1256, https://doi.org/10.1007/s00702-009-0275-0.Search in Google Scholar PubMed

Muller, T., Werne, B., Fowler, B., and Kuhn, W. (1999). Nigral endothelial dysfunction, homocysteine, and Parkinson’s disease. Lancet 354: 126–127, https://doi.org/10.1016/s0140-6736(99)01660-8.Search in Google Scholar PubMed

Mullin, S. and Schapira, A. (2013). alpha-Synuclein and mitochondrial dysfunction in Parkinson’s disease. Mol. Neurobiol. 47: 587–597, https://doi.org/10.1007/s12035-013-8394-x.Search in Google Scholar PubMed PubMed Central

Nevrly, M., Kanovsky, P., Vranova, H., Langova, K., and Hlustik, P. (2010). Effect of entacapone on plasma homocysteine levels in Parkinson’s disease patients. Neurol. Sci. 31: 565–569, https://doi.org/10.1007/s10072-010-0262-0.Search in Google Scholar PubMed

Niu, X., Zheng, S., Liu, H., and Li, S. (2018). Protective effects of taurine against inflammation, apoptosis, and oxidative stress in brain injury. Mol. Med. Rep. 18: 4516–4522, https://doi.org/10.3892/mmr.2018.9465.Search in Google Scholar PubMed PubMed Central

Nuytemans, K., Theuns, J., Cruts, M., and Van Broeckhoven, C. (2010). Genetic etiology of Parkinson disease associated with mutations in the SNCA, PARK2, PINK1, PARK7, and LRRK2 genes: a mutation update. Hum. Mutat. 31: 763–780, https://doi.org/10.1002/humu.21277.Search in Google Scholar PubMed PubMed Central

O’Byrne, M.B. and Tipton, K.F. (2000). Taurine-induced attenuation of MPP+ neurotoxicity in vitro: a possible role for the GABA(A) subclass of GABA receptors. J. Neurochem. 74: 2087–2093, https://doi.org/10.1046/j.1471-4159.2000.0742087.x.Search in Google Scholar PubMed

Obeid, R., Schadt, A., Dillmann, U., Kostopoulos, P., Fassbender, K., and Herrmann, W. (2009). Methylation status and neurodegenerative markers in Parkinson disease. Clin. Chem. 55: 1852–1860, https://doi.org/10.1373/clinchem.2009.125021.Search in Google Scholar PubMed

Ogbodo, J.O., Arazu, A.V., Iguh, T.C., Onwodi, N.J., and Ezike, T.C. (2022). Volatile organic compounds: a proinflammatory activator in autoimmune diseases. Front. Immunol. 13: 928379, https://doi.org/10.3389/fimmu.2022.928379.Search in Google Scholar PubMed PubMed Central

Olanow, C.W. and Tatton, W.G. (1999). Etiology and pathogenesis of Parkinson’s disease. Annu. Rev. Neurosci. 22: 123–144, https://doi.org/10.1146/annurev.neuro.22.1.123.Search in Google Scholar PubMed

Ozkan, S., Colak, O., Kutlu, C., Ertan, M., and Alatas, O. (2004). Plasma homocysteine levels in pergolide-treated Parkinson disease patients. Clin. Neuropharmacol. 27: 163–165, https://doi.org/10.1097/01.wnf.0000136890.78887.b9.Search in Google Scholar PubMed

Palkovits, M., Elekes, I., Lang, T., and Patthy, A. (1986). Taurine levels in discrete brain nuclei of rats. J. Neurochem. 47: 1333–1335, https://doi.org/10.1111/j.1471-4159.1986.tb00761.x.Search in Google Scholar PubMed

Pan, C., Giraldo, G.S., Prentice, H., and Wu, J.Y. (2010). Taurine protection of PC12 cells against endoplasmic reticulum stress induced by oxidative stress. J. Biomed. Sci. 17: S17, https://doi.org/10.1186/1423-0127-17-s1-s17.Search in Google Scholar

Pan, C., Prentice, H., Price, A.L., and Wu, J.Y. (2012). Beneficial effect of taurine on hypoxia- and glutamate-induced endoplasmic reticulum stress pathways in primary neuronal culture. Amino Acids 43: 845–855, https://doi.org/10.1007/s00726-011-1141-6.Search in Google Scholar PubMed

Park, E., Park, S.Y., Dobkin, C., and Schuller-Levis, G. (2014). Development of a novel cysteine sulfinic Acid decarboxylase knockout mouse: dietary taurine reduces neonatal mortality. J. Amino Acids 2014: 346809, https://doi.org/10.1155/2014/346809.Search in Google Scholar PubMed PubMed Central

Parsons, R.B., Waring, R.H., Williams, A.C., and Ramsden, D.B. (2001). Cysteine dioxygenase: regional localisation of protein and mRNA in rat brain. J. Neurosci. Res. 65: 78–84, https://doi.org/10.1002/jnr.1130.Search in Google Scholar PubMed

Pathak, D. and Sriram, K. (2023). Molecular mechanisms underlying neuroinflammation elicited by occupational injuries and toxicants. Int. J. Mol. Sci. 24, https://doi.org/10.3390/ijms24032272.Search in Google Scholar PubMed PubMed Central

Paul, B.D. (2021). Neuroprotective roles of the reverse transsulfuration pathway in Alzheimer’s disease. Front. Aging Neurosci. 13: 659402, https://doi.org/10.3389/fnagi.2021.659402.Search in Google Scholar PubMed PubMed Central

Paul, B.D., Sbodio, J.I., and Snyder, S.H. (2018). Cysteine metabolism in neuronal redox homeostasis. Trends Pharmacol. Sci. 39: 513–524, https://doi.org/10.1016/j.tips.2018.02.007.Search in Google Scholar PubMed PubMed Central

Paul, B.D. and Snyder, S.H. (2015). Modes of physiologic H2S signaling in the brain and peripheral tissues. Antioxid. Redox Signaling 22: 411–423, https://doi.org/10.1089/ars.2014.5917.Search in Google Scholar PubMed PubMed Central

Paul, B.D. and Snyder, S.H. (2018). Gasotransmitter hydrogen sulfide signaling in neuronal health and disease. Biochem. Pharmacol. 149: 101–109, https://doi.org/10.1016/j.bcp.2017.11.019.Search in Google Scholar PubMed PubMed Central

Paul, R. and Borah, A. (2016). L-DOPA-induced hyperhomocysteinemia in Parkinson’s disease: elephant in the room. Biochim. Biophys. Acta 1860: 1989–1997, https://doi.org/10.1016/j.bbagen.2016.06.018.Search in Google Scholar PubMed

Poewe, W., Seppi, K., Tanner, C.M., Halliday, G.M., Brundin, P., Volkmann, J., Schrag, A.E., and Lang, A.E. (2017). Parkinson disease. Nat. Rev. Dis. Prim. 3: 17013, https://doi.org/10.1038/nrdp.2017.13.Search in Google Scholar PubMed

Power, J.H. and Blumbergs, P.C. (2009). Cellular glutathione peroxidase in human brain: cellular distribution, and its potential role in the degradation of Lewy bodies in Parkinson’s disease and dementia with Lewy bodies. Acta Neuropathol. 117: 63–73, https://doi.org/10.1007/s00401-008-0438-3.Search in Google Scholar PubMed

Rae, C.D. and Williams, S.R. (2017). Glutathione in the human brain: review of its roles and measurement by magnetic resonance spectroscopy. Anal. Biochem. 529: 127–143, https://doi.org/10.1016/j.ab.2016.12.022.Search in Google Scholar PubMed

Rafiee, Z., Garcia-Serrano, A.M., and Duarte, J.M.N. (2022). Taurine supplementation as a neuroprotective strategy upon brain dysfunction in metabolic syndrome and diabetes. Nutrients 14: 1292, https://doi.org/10.3390/nu14061292.Search in Google Scholar PubMed PubMed Central

Rehman, T., Shabbir, M.A., Inam-Ur-Raheem, M., Manzoor, M.F., Ahmad, N., Liu, Z.W., Ahmad, M.H., Siddeeg, A., Abid, M., and Aadil, R.M. (2020). Cysteine and homocysteine as biomarker of various diseases. Food Nutr. Sci. 8: 4696–4707, https://doi.org/10.1002/fsn3.1818.Search in Google Scholar PubMed PubMed Central

Religa, D., Czyzewski, K., Styczynska, M., Peplonska, B., Lokk, J., Chodakowska-Zebrowska, M., Stepien, K., Winblad, B., and Barcikowska, M. (2006). Hyperhomocysteinemia and methylenetetrahydrofolate reductase polymorphism in patients with Parkinson’s disease. Neurosci. Lett. 404: 56–60, https://doi.org/10.1016/j.neulet.2006.05.040.Search in Google Scholar PubMed

Repici, M. and Giorgini, F. (2019). DJ-1 in Parkinson’s disease: clinical insights and therapeutic perspectives. J. Clin. Med. 8: 1377, https://doi.org/10.3390/jcm8091377.Search in Google Scholar PubMed PubMed Central

Riederer, P., Sofic, E., Rausch, W.D., Schmidt, B., Reynolds, G.P., Jellinger, K., and Youdim, M.B. (1989). Transition metals, ferritin, glutathione, and ascorbic acid in parkinsonian brains. J. Neurochem. 52: 515–520, https://doi.org/10.1111/j.1471-4159.1989.tb09150.x.Search in Google Scholar PubMed

Rodriguez-Oroz, M.C., Lage, P.M., Sanchez-Mut, J., Lamet, I., Pagonabarraga, J., Toledo, J.B., Garcia-Garcia, D., Clavero, P., Samaranch, L., Irurzun, C., et al.. (2009). Homocysteine and cognitive impairment in Parkinson’s disease: a biochemical, neuroimaging, and genetic study. Mov. Disord. 24: 1437–1444, https://doi.org/10.1002/mds.22522.Search in Google Scholar PubMed

Rogers, J.D., Sanchez-Saffon, A., Frol, A.B., and Diaz-Arrastia, R. (2003). Elevated plasma homocysteine levels in patients treated with levodopa: association with vascular disease. Arch. Neurol. 60: 59–64, https://doi.org/10.1001/archneur.60.1.59.Search in Google Scholar PubMed

Ruotsalainen, M. and Ahtee, L. (1996). Intrastriatal taurine increases striatal extracellular dopamine in a tetrodotoxin-sensitive manner in rats. Neurosci. Lett. 212: 175–178, https://doi.org/10.1016/0304-3940(96)12821-4.Search in Google Scholar PubMed

Sbodio, J.I., Snyder, S.H., and Paul, B.D. (2019). Regulators of the transsulfuration pathway. Br. J. Pharmacol. 176: 583–593, https://doi.org/10.1111/bph.14446.Search in Google Scholar PubMed PubMed Central

Selhub, J. (1999). Homocysteine metabolism. Annu. Rev. Nutr. 19: 217–246, https://doi.org/10.1146/annurev.nutr.19.1.217.Search in Google Scholar PubMed

Shen, X.M. and Dryhurst, G. (1996). Further insights into the influence of L-cysteine on the oxidation chemistry of dopamine: reaction pathways of potential relevance to Parkinson’s disease. Chem. Res. Toxicol. 9: 751–763, https://doi.org/10.1021/tx960008f.Search in Google Scholar PubMed

Shibuya, N., Tanaka, M., Yoshida, M., Ogasawara, Y., Togawa, T., Ishii, K., and Kimura, H. (2009). 3-Mercaptopyruvate sulfurtransferase produces hydrogen sulfide and bound sulfane sulfur in the brain. Antioxid. Redox Signaling 11: 703–714, https://doi.org/10.1089/ars.2008.2253.Search in Google Scholar PubMed

Sian, J., Dexter, D.T., Lees, A.J., Daniel, S., Jenner, P., and Marsden, C.D. (1994). Glutathione-related enzymes in brain in Parkinson’s disease. Ann. Neurol. 36: 356–361, https://doi.org/10.1002/ana.410360306.Search in Google Scholar PubMed

Simon, D.K., Tanner, C.M., and Brundin, P. (2020). Parkinson disease epidemiology, pathology, genetics, and pathophysiology. Clin. Med. Geriatr. 36: 1–12, https://doi.org/10.1016/j.cger.2019.08.002.Search in Google Scholar PubMed PubMed Central

Singh, S., Padovani, D., Leslie, R.A., Chiku, T., and Banerjee, R. (2009). Relative contributions of cystathionine beta-synthase and gamma-cystathionase to H2S biogenesis via alternative trans-sulfuration reactions. J. Biol. Chem. 284: 22457–22466, https://doi.org/10.1074/jbc.m109.010868.Search in Google Scholar

Sipes, I.G., Wiersma, D.A., and Armstrong, D.J. (1986). The role of glutathione in the toxicity of xenobiotic compounds: metabolic activation of 1,2-dibromoethane by glutathione. Adv. Exp. Med. Biol. 197: 457–467, https://doi.org/10.1007/978-1-4684-5134-4_44.Search in Google Scholar PubMed

Slawek, J., Roszmann, A., Robowski, P., Dubaniewicz, M., Sitek, E.J., Honczarenko, K., Gorzkowska, A., Budrewicz, S., Mak, M., Golab-Janowska, M., et al.. (2013). The impact of MRI white matter hyperintensities on dementia in Parkinson’s disease in relation to the homocysteine level and other vascular risk factors. Neurodegener. Dis. 12: 1–12, https://doi.org/10.1159/000338610.Search in Google Scholar PubMed

Smeyne, M. and Smeyne, R.J. (2013). Glutathione metabolism and Parkinson’s disease. Free Radic. Biol. Med. 62: 13–25, https://doi.org/10.1016/j.freeradbiomed.2013.05.001.Search in Google Scholar PubMed PubMed Central

Sofic, E., Riederer, P., Heinsen, H., Beckmann, H., Reynolds, G.P., Hebenstreit, G., and Youdim, M.B. (1988). Increased iron (III) and total iron content in post mortem substantia nigra of parkinsonian brain. J. Neural. Transm. 74: 199–205, https://doi.org/10.1007/bf01244786.Search in Google Scholar

Song, I.U., Kim, J.S., Park, I.S., Kim, Y.D., Cho, H.J., Chung, S.W., and Lee, K.S. (2013). Clinical significance of homocysteine (hcy) on dementia in Parkinson’s disease (PD). Arch. Gerontol. Geriatr. 57: 288–291, https://doi.org/10.1016/j.archger.2013.04.015.Search in Google Scholar PubMed

Spencer, J.P., Jenner, P., Daniel, S.E., Lees, A.J., Marsden, D.C., and Halliwell, B. (1998). Conjugates of catecholamines with cysteine and GSH in Parkinson’s disease: possible mechanisms of formation involving reactive oxygen species. J. Neurochem. 71: 2112–2122, https://doi.org/10.1046/j.1471-4159.1998.71052112.x.Search in Google Scholar PubMed

Stead, L.M., Jacobs, R.L., Brosnan, M.E., and Brosnan, J.T. (2004). Methylation demand and homocysteine metabolism. Adv. Enzym. Regul. 44: 321–333, https://doi.org/10.1016/j.advenzreg.2003.11.012.Search in Google Scholar PubMed

Stipanuk, M.H., Dominy, J.E.Jr., Lee, J.I., and Coloso, R.M. (2006). Mammalian cysteine metabolism: new insights into regulation of cysteine metabolism. J. Nutr. 136: 1652S–1659S, https://doi.org/10.1093/jn/136.6.1652s.Search in Google Scholar

Streck, E.L., Matte, C., Vieira, P.S., Calcagnotto, T., Wannmacher, C.M., Wajner, M., and Wyse, A.T. (2003). Impairment of energy metabolism in hippocampus of rats subjected to chemically-induced hyperhomocysteinemia. Biochim. Biophys. Acta 1637: 187–192, https://doi.org/10.1016/s0925-4439(03)00019-x.Search in Google Scholar PubMed

Tabassum, R. and Jeong, N.Y. (2019). Potential for therapeutic use of hydrogen sulfide in oxidative stress-induced neurodegenerative diseases. Int. J. Med. Sci. 16: 1386–1396, https://doi.org/10.7150/ijms.36516.Search in Google Scholar PubMed PubMed Central

Tang, X.Q., Fan, L.L., Li, Y.J., Shen, X.T., Zhuan, Y.Y., He, J.Q., Xu, J.H., Hu, B., and Li, Y.J. (2011). Inhibition of hydrogen sulfide generation contributes to 1-methy-4-phenylpyridinium ion-induced neurotoxicity. Neurotox. Res. 19: 403–411, https://doi.org/10.1007/s12640-010-9180-4.Search in Google Scholar PubMed

Tawfik, A., Elsherbiny, N.M., Zaidi, Y., and Rajpurohit, P. (2021). Homocysteine and age-related central nervous system diseases: role of inflammation. Int. J. Mol. Sci. 22, https://doi.org/10.3390/ijms22126259.Search in Google Scholar PubMed PubMed Central

Tian, T., Zhang, B.Y., Wang, K.D., Zhang, B.F., and Huang, M. (2020). Protective effects of taurine on neurons and microglia in Parkinson’s disease-like mouse model induced by paraquat. Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi 38: 801–808, https://doi.org/10.3760/cma.j.cn121094-20200121-00036.Search in Google Scholar PubMed

Tiong, C.X., Lu, M., and Bian, J.S. (2010). Protective effect of hydrogen sulphide against 6-OHDA-induced cell injury in SH-SY5Y cells involves PKC/PI3K/Akt pathway. Br. J. Pharmacol. 161: 467–480, https://doi.org/10.1111/j.1476-5381.2010.00887.x.Search in Google Scholar PubMed PubMed Central

Todorovic, Z., Dzoljic, E., Novakovic, I., Mirkovic, D., Stojanovic, R., Nesic, Z., Krajinovic, M., Prostran, M., and Kostic, V. (2006). Homocysteine serum levels and MTHFR C677T genotype in patients with Parkinson’s disease, with and without levodopa therapy. J. Neurol. Sci. 248: 56–61, https://doi.org/10.1016/j.jns.2006.05.040.Search in Google Scholar PubMed

Twelves, D., Perkins, K.S., and Counsell, C. (2003). Systematic review of incidence studies of Parkinson’s disease. Mov. Disord. 18: 19–31, https://doi.org/10.1002/mds.10305.Search in Google Scholar PubMed

Tysnes, O.B. and Storstein, A. (2017). Epidemiology of Parkinson’s disease. J. Neural. Transm. 124: 901–905, https://doi.org/10.1007/s00702-017-1686-y.Search in Google Scholar PubMed

Valdovinos-Flores, C. and Gonsebatt, M.E. (2012). The role of amino acid transporters in GSH synthesis in the blood-brain barrier and central nervous system. Neurochem. Int. 61: 405–414, https://doi.org/10.1016/j.neuint.2012.05.019.Search in Google Scholar PubMed

Vallelunga, A., Pegoraro, V., Pilleri, M., Biundo, R., De Iuliis, A., Marchetti, M., Facchini, S., Formento Dojot, P., and Antonini, A. (2014). The MTHFR C677T polymorphism modifies age at onset in Parkinson’s disease. Neurol. Sci. 35: 73–77, https://doi.org/10.1007/s10072-013-1545-z.Search in Google Scholar PubMed

Vandiver, M.S., Paul, B.D., Xu, R., Karuppagounder, S., Rao, F., Snowman, A.M., Ko, H.S., Lee, Y.I., Dawson, V.L., Dawson, T.M., et al.. (2013). Sulfhydration mediates neuroprotective actions of parkin. Nat. Commun. 4: 1626, https://doi.org/10.1038/ncomms2623.Search in Google Scholar PubMed PubMed Central

Vida, C., Kobayashi, H., Garrido, A., Martinez de Toda, I., Carro, E., Molina, J.A., and De la Fuente, M. (2019). Lymphoproliferation impairment and oxidative stress in blood cells from early Parkinson’s disease patients. Int. J. Mol. Sci. 20: 771, https://doi.org/10.3390/ijms20030771.Search in Google Scholar PubMed PubMed Central

Verina, T., Schneider, J.S., and Guilarte, T.R. (2013). Manganese exposure induces α-synuclein aggregation in the frontal cortex of non-human primates. Toxicol. Lett. 217: 177–183, https://doi.org/10.1016/j.toxlet.2012.12.006.Search in Google Scholar PubMed PubMed Central

Vitvitsky, V., Garg, S.K., and Banerjee, R. (2011). Taurine biosynthesis by neurons and astrocytes. J. Biol. Chem. 286: 32002–32010, https://doi.org/10.1074/jbc.m111.253344.Search in Google Scholar

Wang, K., Shi, Y., Liu, W., Liu, S., and Sun, M.Z. (2021). Taurine improves neuron injuries and cognitive impairment in a mouse Parkinson’s disease model through inhibition of microglial activation. Neurotoxicology 83: 129–136, https://doi.org/10.1016/j.neuro.2021.01.002.Search in Google Scholar PubMed

Weimbs, T. and Stoffel, W. (1992). Proteolipid protein (PLP) of CNS myelin: positions of free, disulfide-bonded, and fatty acid thioester-linked cysteine residues and implications for the membrane topology of PLP. Biochemistry 31: 12289–12296, https://doi.org/10.1021/bi00164a002.Search in Google Scholar PubMed

Whitehead, R.E., Ferrer, J.V., Javitch, J.A., and Justice, J.B. (2001). Reaction of oxidized dopamine with endogenous cysteine residues in the human dopamine transporter. J. Neurochem. 76: 1242–1251, https://doi.org/10.1046/j.1471-4159.2001.00125.x.Search in Google Scholar PubMed

Wojcik, O.P., Koenig, K.L., Zeleniuch-Jacquotte, A., Costa, M., and Chen, Y. (2010). The potential protective effects of taurine on coronary heart disease. Atherosclerosis 208: 19–25, https://doi.org/10.1016/j.atherosclerosis.2009.06.002.Search in Google Scholar PubMed PubMed Central

Wu, D., Wang, H., Teng, T., Duan, S., Ji, A., and Li, Y. (2018). Hydrogen sulfide and autophagy: a double edged sword. Pharmacol. Res. 131: 120–127, https://doi.org/10.1016/j.phrs.2018.03.002.Search in Google Scholar PubMed

Wu, H., Jin, Y., Wei, J., Jin, H., Sha, D., and Wu, J.Y. (2005). Mode of action of taurine as a neuroprotector. Brain Res. 1038: 123–131, https://doi.org/10.1016/j.brainres.2005.01.058.Search in Google Scholar PubMed

Xiao, Q., Ying, J., Xiang, L., and Zhang, C. (2018). The biologic effect of hydrogen sulfide and its function in various diseases. Medicine 97: e13065, https://doi.org/10.1097/md.0000000000013065.Search in Google Scholar PubMed PubMed Central

Xie, L., Hu, L.F., Teo, X.Q., Tiong, C.X., Tazzari, V., Sparatore, A., Del Soldato, P., Dawe, G.S., and Bian, J.S. (2013). Therapeutic effect of hydrogen sulfide-releasing L-Dopa derivative ACS84 on 6-OHDA-induced Parkinson’s disease rat model. PLoS One 8: e60200, https://doi.org/10.1371/journal.pone.0060200.Search in Google Scholar PubMed PubMed Central

Xie, L., Tiong, C.X., and Bian, J.S. (2012). Hydrogen sulfide protects SH-SY5Y cells against 6-hydroxydopamine-induced endoplasmic reticulum stress. Am. J. Physiol. Cell Physiol. 303: C81–C91, https://doi.org/10.1152/ajpcell.00281.2011.Search in Google Scholar PubMed

Yang, G., Zhao, K., Ju, Y., Mani, S., Cao, Q., Puukila, S., Khaper, N., Wu, L., and Wang, R. (2013). Hydrogen sulfide protects against cellular senescence via S-sulfhydration of Keap1 and activation of Nrf2. Antioxid. Redox Signaling 18: 1906–1919, https://doi.org/10.1089/ars.2012.4645.Search in Google Scholar PubMed

Yap, S. (2003). Classical homocystinuria: vascular risk and its prevention. J. Inherit. Metab. Dis. 26: 259–265, https://doi.org/10.1023/a:1024497419821.10.1023/A:1024497419821Search in Google Scholar

Yasui, K., Kowa, H., Nakaso, K., Takeshima, T., and Nakashima, K. (2000). Plasma homocysteine and MTHFR C677T genotype in levodopa-treated patients with PD. Neurology 55: 437–440, https://doi.org/10.1212/wnl.55.3.437.Search in Google Scholar PubMed

Ye, G., Tse, A.C., and Yung, W. (1997). Taurine inhibits rat substantia nigra pars reticulata neurons by activation of GABA- and glycine-linked chloride conductance. Brain Res. 749: 175–179, https://doi.org/10.1016/s0006-8993(96)01427-8.Search in Google Scholar PubMed

Yi, P., Melnyk, S., Pogribna, M., Pogribny, I.P., Hine, R.J., and James, S.J. (2000). Increase in plasma homocysteine associated with parallel increases in plasma S-adenosylhomocysteine and lymphocyte DNA hypomethylation. J. Biol. Chem. 275: 29318–29323, https://doi.org/10.1074/jbc.m002725200.Search in Google Scholar PubMed

Yin, G., Gan, Y., Jiang, H., Yu, T., Liu, M., Zhang, Y., Li, H., Yin, P., and Yao, S. (2021). Direct quantification and visualization of homocysteine, cysteine, and glutathione in Alzheimer’s and Parkinson’s disease model tissues. Anal. Chem. 93: 9878–9886, https://doi.org/10.1021/acs.analchem.1c01945.Search in Google Scholar PubMed

Yin, W.L., He, J.Q., Hu, B., Jiang, Z.S., and Tang, X.Q. (2009). Hydrogen sulfide inhibits MPP(+)-induced apoptosis in PC12 cells. Life Sci. 85: 269–275, https://doi.org/10.1016/j.lfs.2009.05.023.Search in Google Scholar PubMed

Yin, W.L., Yin, W.G., Huang, B.S., and Wu, L.X. (2017). Neuroprotective effects of lentivirus-mediated cystathionine-beta-synthase overexpression against 6-OHDA-induced Parkinson’s disease rats. Neurosci. Lett. 657: 45–52, https://doi.org/10.1016/j.neulet.2017.07.019.Search in Google Scholar PubMed

Yoon, J.H., Lee, J.S., Yong, S.W., Hong, J.M., and Lee, P.H. (2014). Endothelial dysfunction and hyperhomocysteinemia in Parkinson’s disease: flow-mediated dilation study. Mov. Disord. 29: 1551–1555, https://doi.org/10.1002/mds.26005.Search in Google Scholar PubMed

Yuan, L., Song, Z., Deng, X., Xiong, W., Yang, Z., and Deng, H. (2016). Association of the MTHFR rs1801131 and rs1801133 variants in sporadic Parkinson’s disease patients. Neurosci. Lett. 616: 26–31, https://doi.org/10.1016/j.neulet.2016.01.031.Search in Google Scholar PubMed

Yuan, R.Y., Sheu, J.J., Yu, J.M., Hu, C.J., Tseng, I.J., Ho, C.S., Yeh, C.Y., Hung, Y.L., and Chiang, T.R. (2009). Methylenetetrahydrofolate reductase polymorphisms and plasma homocysteine in levodopa-treated and non-treated Parkinson’s disease patients. J. Neurol. Sci. 287: 64–68, https://doi.org/10.1016/j.jns.2009.09.007.Search in Google Scholar PubMed

Yuan, Y.Q., Wang, Y.L., Yuan, B.S., Yuan, X., Hou, X.O., Bian, J.S., Liu, C.F., and Hu, L.F. (2018). Impaired CBS-H(2)S signaling axis contributes to MPTP-induced neurodegeneration in a mouse model of Parkinson’s disease. Brain Behav. Immun. 67: 77–90, https://doi.org/10.1016/j.bbi.2017.07.159.Search in Google Scholar PubMed

Zhang, D., Du, J., Tang, C., Huang, Y., and Jin, H. (2017). H(2)S-Induced sulfhydration: biological function and detection methodology. Front. Pharmacol. 8: 608, https://doi.org/10.3389/fphar.2017.00608.Search in Google Scholar PubMed PubMed Central

Zhang, L., Yuan, Y., Tong, Q., Jiang, S., Xu, Q., Ding, J., Zhang, L., Zhang, R., and Zhang, K. (2016). Reduced plasma taurine level in Parkinson’s disease: association with motor severity and levodopa treatment. Int. J. Oper. Res. 126: 630–636, https://doi.org/10.3109/00207454.2015.1051046.Search in Google Scholar PubMed

Zhang, S., Wang, R., and Wang, G. (2019). Impact of dopamine oxidation on dopaminergic neurodegeneration. ACS Chem. Neurosci. 10: 945–953, https://doi.org/10.1021/acschemneuro.8b00454.Search in Google Scholar PubMed

Zheng, W. and Monnot, A.D. (2012). Regulation of brain iron and copper homeostasis by brain barrier systems: implication in neurodegenerative diseases. Pharmacol. Ther. 133: 177–188, https://doi.org/10.1016/j.pharmthera.2011.10.006.Search in Google Scholar PubMed PubMed Central

Zhong, H., Yu, H., Chen, J., Sun, J., Guo, L., Huang, P., and Zhong, Y. (2020). Hydrogen sulfide and endoplasmic reticulum stress: a potential therapeutic target for central nervous system degeneration diseases. Front. Pharmacol. 11: 702, https://doi.org/10.3389/fphar.2020.00702.Search in Google Scholar PubMed PubMed Central

Zoccolella, S., Lamberti, P., Armenise, E., de Mari, M., Lamberti, S.V., Mastronardi, R., Fraddosio, A., Iliceto, G., and Livrea, P. (2005). Plasma homocysteine levels in Parkinson’s disease: role of antiparkinsonian medications. Parkinsonism Relat. Disord. 11: 131–133, https://doi.org/10.1016/j.parkreldis.2004.07.008.Search in Google Scholar PubMed

Received: 2023-03-31
Accepted: 2023-06-04
Published Online: 2023-07-07
Published in Print: 2023-12-15

© 2023 the author(s), published by De Gruyter, Berlin/Boston

This work is licensed under the Creative Commons Attribution 4.0 International License.

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