北五味子酸性多糖对阿尔茨海默病模型小鼠学习记忆能力的改善作用

Improvement of acidic polysaccharose of Schisandra Chinensis on learning and memory functions of Alzheimer's disease model mice

目的:观察北五味子酸性多糖(SCP-A)对Aβ25-35致阿尔茨海默病(AD)模型小鼠学习记忆能力的改善作用,并阐明其相关机制。方法:75只雄性C57BL小鼠随机分为空白组(侧脑室注射生理盐水,灌胃蒸馏水),模型组(侧脑室注射Aβ_(25-35),灌胃蒸馏水),5、10和20 mg·kg-1 SCP-A组(侧脑室注射Aβ25-35,灌胃SCP-A),每组15只。灌胃药物每日1次,连续14d,于第8天给予Aβ25-35进行侧脑室注射。给药完毕后,第15天依次进行避暗实验及Morris水迷宫实验观察小鼠的潜伏期、错误次数、找到平台时间、穿越平台次数和目标象限停留时间,Western blotting法检测小鼠海马组织中Tau蛋白、糖原合成酶激酶3(GSK-3β)及其磷酸化蛋白的表达水平。结果:避暗实验,与空白组比较,模型组小鼠潜伏期明显缩短,错误次数明显升高(P<0.01);与模型组比较,10和20mg·kg-1 SCP-A组小鼠潜伏期明显延长(P<0.01),错误次数明显减少(P<0.05或P<0.01)。Morris水迷宫,与空白组比较,模型组小鼠找到平台时间明显延长(P<0.01),穿越平台次数及目标象限停留时间明显缩短(P<0.01);与模型组比较,10和20mg·kg-1 SCP-A组小鼠找到平台时间明显缩短(P<0.01),穿过平台次数及平台区域停留时间明显增加(P<0.01)。Western blotting法检测,与模型组比较,20mg·kg-1SCP-A组小鼠海马组织中磷酸化蛋白Tau Ser199、Tau Ser396及Tau Ser404表达水平明显降低(P<0.05),GSK-3β表达水平明显降低(P<0.01),磷酸化蛋白GSK-3βTyr216相对表达水平明显降低(P<0.05),磷酸化蛋白GSK-3βSer9相对表达水平明显升高(P<0.05)。结论:SCP-A具有抗AD作用,该作用与其调节GSK-3β活性进而降低海马组织中Tau蛋白磷酸化水平有关。

Objective:To observe the improvement of acidic polysaccharose of Schisandrae Chinensis(SCP-A)on the learning and memory functions of Alzheimer’s disease(AD)model mice induced by Aβ25-35,and to clarify the related mechanisms Methods:A total of75male C57BL mice were randomly divided into control group(injected with saline in intracerebroventricular,given distilled water intragastrically),model group(injected with Aβ25-35intracerebroventricularly,given distilled water intragastrically),and5,10,20mg·kg-1SCP-A groups(injected with Aβ25-35intracerebroventricularly,given SCP-A intragastrically)(n=15).The agents were administered once daily for14d,in which Aβ25-35was injected intracerebroventricularly on the8th day.On the15th day after administration,step through test and Morris water maze test were used to detect the escape latency,number of errors,and time of finding platform,number of passing platforms,dwell time in target quadrant of the mice;Western blotting method was used to detected the levels of Tau,GSK-3βand their phosphorylated proteins in hippocampus tissue of the mice.Results:The step through test results showed that compared with control group,the escape latency of the mice in model group was obviously shortened and the number of errors was significantly increased(P<0.01);compared with model group,the escape latencies of the mice in10and20mg·kg-1SCP-A groups were significantly prolonged(P<0.01),the number of errors was significantly decreased(P<0.05or P<0.01).The Morris water maze test results showed that compared with control group,the time of finding platform of the mice in model group was significantly prolonged,the number of passing platform and dwell time in target quadrant were significantly reduced(P<0.01);compared with model group,the time of finding platform of the mice in10and20mg·kg-1SCP-A groups was significantly shortened(P<0.01),and the number of passing platform and the dwell time in target quadrant were significantly increased(P<0.01).The Western blotting results showed that compared with model group,the expression levels of phosphorylated protein Tau Ser199,Tau Ser396and Tau Ser404in hippocampus of the mice in20mg·kg-1SCP-A group were significantly decreased(P<0.05),and the expression level of GSK-3βwas significantly decreased(P<0.01);the expression level of phosphorylated protein GSK-3βTyr216was significantly decreased,and the expression level of phosphorylated protein GSK-3βSer9was significantly increased(P<0.05).Conclusion:SCP-A has an anti AD effect,which is related to regulating the activity of GSK-3βto reduce the level of phosphorylated protein Tau in the hippocampus tissue of the mice.