Objective:To investigate the preventive and protective effects of Schisandrin B in the mice of Alzheimer's disease (AD),and to clarify its mechanism.Methods:Fifty Balb/c mice were randomly divided into blank group,model group,pasitive control group,low dose of Schisandrin B group(0.1 g·kg-1)and high dose of Schisandrin B group(0.5 g·kg-1);there were 10 mice in each group.Step-through test was conducted after last administration to detect the latencies and number of errors of the mice in various groups,and the brain tissue was taken.Congo red staining was to detect the morphology changes of cells and neuronal amyloidosis in brain tissue of the mice.The levels of ROS in brain tissue of the mice were tested by Flow Cytometry.The contents of MDA,the levels of LDH,and the activities of CAT,GSH-Px and SOD in brain tissue of the mice were tested by biochemical method.Western blotting method was used to detect the expression levels of signaling pathway proteins Nrf2 and Keap1 in brain tissue of the mice.Results:Compared with model group,the latencies of the mice in low and high dose of Schisandrin B groups were increased (P<0.01) and the number of errors in step-through tests was decreased (P<0.05 or P<0.01).The Congo red staining results showed that compared with model group,the neuronal amyloidosis in brain tissue of the mice in Schisandrin B groups was decreased significantly.Compared with model group,the levels of ROS,LDH and the contents of MDA in brain tissue of the mice in low and high doses of Schisandrin B groups were decreased (P<0.05 or P<0.01),and the activities of CAT,SOD and GSH-Px were increased (P<0.01).Compared with low dose of Schisandrin B group,the content of MDA and the activities of SOD and GSH-Px in brain tissue of the mice in high dose of Schisandrin B group were increased (P<0.001).Compared with model group,the expression level of Nrf2 protein in brain tissue of the mice in low dose of Schisandrin B group was increased (P<0.01),while the expression level of Nrf2 protein in brain tissue of the mice in high dose of Schisandrin B group was decreased (P<0.01);the expression levels of Keap1 protein in brain tissue of the mice in low and high doses of Schisandrin B groups was decreased (P<0.01).Conclusion:Schisandrin B could decrease the level of peroxidation in brain tissue of the mice and reduce the oxidative damage and improve the memory function of the AD mice.The mechanism is related to the activation of Nrf2 signaling pathway which improve the activity of antioxidant enzymes.%目的:探讨五味子乙素对阿尔兹海默病(AD)模型小鼠的预防保护作用,阐明其作用机制.方法:50只Balb/c小鼠随机分为空白组、模型组、阳性药对照组、低剂量五味子乙素组(0.1 g·kg-1)和高剂量五味子乙素组(0.5 g·kg-1),每组10只.小鼠避暗实验观察各组小鼠避暗潜伏期和避暗实验错误次数;末次给药后取小鼠脑组织行刚果红染色,观察小鼠脑组织中细胞形态改变与淀粉样变;流式细胞术测定小鼠脑组织中ROS水平;生化法测定小鼠脑组织中丙二醛(MDA)含量、乳酸脱氢酶(LDH)水平及过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)活性;Western blotting法检测小鼠脑组织中细胞信号通路蛋白Nrf2和Keap1表达水平.结果:与模型组比较,低和高剂量五味子乙素组小鼠避暗潜伏期延长(P<0.01),避暗实验错误次数减少(P<0.05或P<0.01).刚果红染色,与模型组比较,低和高剂量五味子乙素组小鼠脑组织神经元中淀粉样变表现明显减轻;低和高剂量五味子乙素组小鼠脑组织中ROS和LDH水平及MDA含量明显降低(P<0.05或P<0.01),CAT、SOD和GSH-Px活性明显升高(P<0.01);高剂量五味子乙素组小鼠MDA含量和SOD及GSH-Px活性均高于低剂量五味子乙素组(P<0.01).与模型组比较,低剂量五味子乙素组小鼠脑组织中Nrf2蛋白表达水平升高(P<0.01),高剂量五味子乙素组小鼠脑组织中Nrf2蛋白表达水平降低(P<0.01);低和高剂量五味子乙素组小鼠脑组织中Keap1蛋白表达水平均降低(P<0.01).结论:五味子乙素可降低小鼠脑组织过氧化水平,减轻氧化损伤,从而改善AD小鼠的记忆功能,其机制与激活Nrf2信号通路提高抗氧化酶活性有关.
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