The neuroprotective effect of Dl-3-n-butylphthalide in epileptic rats via inhibiting endoplasmic reticulum stress

Introduction:
The purpose of this study is to investigate whether Dl-3-n-Butylphthalide (NBP) has a neuroprotective effect on pilocarpine-induced epileptic (EP) rats through endoplasmic reticulum stress (ERS)-mediated apoptosis.

Material and methods:
The Sprague-Dawley rats were divided into four groups: control (CON), EP, EP + NBP₆₀ (NBP 60 mg/kg) and EP + NBP₁₂₀ (NBP 120 mg/kg) groups. After the successful establishment of the temporal lobe EP model using the lithium-pilocarpine, the rats were given NBP for 28 consecutive days in EP + NBP₆₀ and EP + NBP₁₂₀ groups. Then, the spontaneous recurrent seizure (SRS) latency, SRS frequency and seizure duration were observed in each group. In order to observe the abnormal discharge of rats, the intracranial electrodes were implanted to monitor the electroencephalogram. Nissl staining was used to observe the damage to the hippocampal CA1 neurons, TUNEL staining was employed to observe hippocampal neuronal apoptosis. Western blot was used to detect the expression of ERS and ERS-mediated apoptotic proteins.

Results:
NBP₆₀ and NBP₁₂₀ decreased SRS frequency (all p < 0.05), shortened seizure duration (all p < 0.05), and reduced the abnormal discharge of the brain. Nissl staining and TUNEL staining results show that NBP protected the hippocampal neurons from damage (all p < 0.05) and inhibited hippocampal neuronal apoptosis in EP rats (all p < 0.05). NBP₆₀ and NBP₁₂₀ could reduce ERS and ERS-mediated apoptotic protein expression in EP rats (all p < 0.05). In addition, the therapeutic effect of NBP on epilepsy in rats is dose-dependent. The SRS frequency of the EP + NBP₁₂₀ group was lower, and the seizure duration was shorter than in the EP + NBP₆₀ group (all p < 0.05), and there were more neurons in the EP + NBP₁₂₀ group than in the EP + NBP₆₀ group (p < 0.05).

Conclusions:
NBP had a significant neuroprotective effect in EP rats. Large doses of NBP are more effective than low doses. The mechanism may be associated with the inhibition of ERS and ERS-mediated apoptosis.