Background

The pathophysiology of diabetic retinopathy (DR) is thought to be influenced by oxidative stress. Astaxanthin (ASX) is a natural product with antioxidant effect, but it is not clear whether its mechanism of inhibiting the development of DR is related to anti-oxidation.

Methods

Rats were intraperitoneally injected with streptozotocin (60 mg/kg) to create DR rat models followed by ASX (20 mg/kg) for 45 days. Retinal tissue was examined by Hematoxylin and Eosin staining. By using Enzyme-linked immunosorbent assay (ELISA), 2,7-Dichlorodrhydrofluorescein diace (DCFH-DA) probes, immunohistochemistry and western blot, it was feasible to evaluate the contents of inflammation-related factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and macrophage inhibitory cytokine-1 (MIC-1)), oxidative stress-related indicators (glutathione (GSH), malonic dialdehyde (MDA), glutathione peroxidase (GPx), reactive oxygen species (ROS) and Total antioxidant capacity (T-AOC)), antioxidant enzymes (hemoxgenase-1(HO-1) and Quinone Oxidoreductase 1 (NQO1)), and apoptosis-related proteins (Bcl-2, Bcl2 Associated X Protein (BAX), and cleaved-caspase-3). Additionally, antioxidant proteins downstream of the nuclear factor E2 related factors (Nrf-2) pathway, expression levels of Nrf2/ Kelch-like ECH-associated protein 1(Keap 1) pathway-associated proteins, and nuclear and cytoplasmic levels of Nrf2 were assessed using immunohistochemistry, western blot, or quantitative real-time polymerase chain reaction (qRT-PCR).

Results

ASX alleviated retinal tissue damage by increasing overall retina thickness and ganglion cell layer (GCL) cell numbers and exerted the anti-inflammatory, anti-oxidative stress, and anti-apoptosis effects in DR rats. Additionally, ASX could inhibit the expression of Keap1, promote the transport of Nrf2 from cytoplasm to nucleus and facilitate the expressions of HO-1, NQO1, γ-glutamylcysteine synthetase, (γ-GCS) and GPx.

Conclusion

ASX exerted antioxidant effects through Nrf2/keap1 pathway, thereby alleviating apoptosis, inflammation, and oxidative stress in retinal tissues of DR rats.

中文翻译：

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虾青素抑制糖尿病视网膜病变的氧化应激和细胞凋亡

背景

糖尿病视网膜病变（DR）的病理生理学被认为受到氧化应激的影响。虾青素（ASX）是一种具有抗氧化作用的天然产物，但其抑制DR发生的机制是否与抗氧化有关尚不清楚。

方法

给大鼠腹腔注射链脲佐菌素(60 mg/kg) 以创建 DR 大鼠模型，然后注射 ASX (20 mg/kg) 45 天。通过苏木精和伊红染色检查视网膜组织。采用酶联免疫吸附法（ELISA）、2,7-二氯氢荧光素双酶（DCFH-DA）探针、免疫组化和Western blot等方法评价炎症相关因子（肿瘤坏死因子-α（TNF-α））的含量是可行的。 α）、白细胞介素-1β（IL-1β）、IL-6和巨噬细胞抑制性细胞因子-1（MIC-1））、氧化应激相关指标（谷胱甘肽（GSH）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GPx ） 、活性氧（ROS）和总抗氧化能力（T-AOC））、抗氧化酶（血氧合酶-1（HO-1）和醌氧化还原酶1（NQO1））以及凋亡相关蛋白（Bcl-2、Bcl2相关蛋白） X 蛋白 (BAX) 和 cleaved-caspase-3)。此外，还评估了核因子 E2 相关因子 (Nrf-2) 途径下游的抗氧化蛋白、Nrf2/Kelch 样 ECH 相关蛋白 1(Keap 1) 途径相关蛋白的表达水平以及 Nrf2 的核和细胞质水平使用免疫组织化学、蛋白质印迹或定量实时聚合酶链反应 (qRT-PCR)。

结果

ASX 通过增加视网膜整体厚度和神经节细胞层 (GCL) 细胞数量来减轻视网膜组织损伤，并在 DR 大鼠中发挥抗炎、抗氧化应激和抗凋亡作用。此外，ASX还可以抑制Keap1的表达，促进Nrf2从细胞质向细胞核的转运，并促进HO-1、NQO1、γ-谷氨酰半胱氨酸合成酶、(γ-GCS)和GPx的表达。

结论

ASX通过Nrf2/keap1通路发挥抗氧化作用，从而减轻DR大鼠视网膜组织的细胞凋亡、炎症和氧化应激。