醉茄素A对缺血性脑卒中大鼠的神经保护作用及其机制

Neuroprotective effect of Withaferin A on ischemic stroke rats and its mechanism

目的:探讨醉茄素A对缺血性脑卒中大鼠神经功能的保护作用,阐明其可能作用机制。方法:75只SD大鼠随机分为假手术组、模型组、阳性对照组(尼莫地平组,12 mg·kg^(-1))、低剂量醉茄素A组(25 mg·kg^(-1))和高剂量醉茄素A组(100 mg·kg^(-1)),每组15只。采用改良Longa线栓法制备缺血性脑卒中大鼠模型,建模成功后灌胃给药,每天1次,连续14 d。采用Zea-Longa评分法评估各组大鼠神经功能,检测大鼠脑组织含水量,TTC染色法检测大鼠脑梗死体积,生化法检测大鼠脑组织中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活性和丙二醛(MDA)水平,TUNEL染色法检测大鼠脑细胞凋亡率,实时荧光定量PCR(RT-qPCR)和Western blotting法检测大鼠脑组织中核因子E2相关因子2(Nrf2)和血红素加氧酶1(HO-1)mRNA和蛋白表达水平。结果:与假手术组比较,模型组大鼠神经功能评分、脑组织含水量、脑梗死体积、细胞凋亡率和脑组织中MDA水平均明显升高(P<0.05),脑组织中SOD、GSH-Px、CAT活性及Nrf2、HO-1 mRNA和蛋白表达水平明显降低(P<0.05);与模型组比较,尼莫地平组和高剂量醉茄素A组大鼠神经功能评分、脑组织含水量、脑梗死体积、细胞凋亡率和脑组织中MDA水平明显降低(P<0.05),脑组织中SOD、GSH-Px和CAT活性及Nrf2、HO-1 mRNA和蛋白表达水平均明显升高(P<0.05),而低剂量醉茄素A组大鼠上述指标差异无统计学意义(P>0.05)。结论:醉茄素A能提高缺血性脑卒中大鼠机体抗氧化水平,减轻脑组织氧化损伤,抑制脑组织神经细胞凋亡,改善大鼠神经行为功能,其机制可能与Nrf2/HO-1信号通路的激活有关。

Objective:To investigate the protective effect of Withaferin A on the neurological function of the rats with ischemic stroke,and to clarify its possible mechanism.Methods:A total of 75 SD rats were randomly divided into sham operation group,model group,positive control group(nimodipine group,12 mg·kg^(-1)),low dose of Withaferin A group(25 mg·kg^(-1))and high dose of Withaferin A group(100 mg·kg^(-1)),and there were 15 rats in each group.The rat models of ischemic stroke were established by improved Longa line embolization.After successful modeling,the drugs were administered by gavage once per day for 14 d.Subsequently,the neurological function,the content of water in brain and the volume of cerebral infarction were evaluated.The activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-PX),catalase(CAT)and the levels of malondialdehyde(MDA)in brain tissue of the rats were determined by biochemical method.The apoptotic rates of cells of the rats were detected by TUNEL staining,and the mRNA and protein expression levels of nuclear E2-related factors 2(Nrf2)and heme oxygenase-1(HO-1)in brain tissue of the rats were respectively detected by RT-qPCR and Western blotting methods.Results:Compared with sham operation group,the score of neurological function,the volume of cerebral infarction,the content of water in brain tissue,the apoptotic rate of cells and the level of MDA in brain tissue of the rats in model group were significantly increased(P<0.05),while the activities of SOD,GSH-PX and CAT,as well as the mRNA and protein expression levels of Nrf2 and HO-1 in brain tissue of the rats were significantly decreased(P<0.05).Compared with model group,the scores of neurological function,the volumes of cerebral infarction,the contents of water in brain tissue,the apoptotic rates of cells and the levels of MDA in brain tissue of the rats in high dose of Withaferin A group and nimodipine group were significantly reduced(P<0.05),and the activities of SOD,GSH-PX and CAT as well as the mRNA and protein expression levels of Nrf2 and HO-1 in brain tissue of the rats were significantly increased(P<0.05);However,there were no significant differences in the related indexes in low dose of Withaferin A group(P>0.05).Conclusion:Withaferin A can improve the level of antioxidant in the rats with ischemic stroke,reduce the oxidative damage of brain tissue,inhibit the apoptosis of nerve cells of brain tissue,and improve the neurological function of the rats;its mechanism may be related to the activation of Nrf2/HO-1 signaling pathway.