小檗碱对三转基因阿尔茨海默病小鼠的学习记忆和海马PSD95突触相关蛋白表达水平的影响

摘要

目的 探讨小檗碱(BBR)对三转基因阿尔茨海默病(AD)小鼠的学习记忆及海马组织 PSD95突触蛋白表达水平的影响.方法 将30只三转基因(APP/Tau/PS1)AD小鼠按随机数字表法分成3组,即AD对照组、AD+25 mgBBR组、AD+50 mgBBR,每组各10只,后2组以灌胃方式且剂量分别为25 mg·kg -1 ·d-1、50 mg·kg -1·d-1,对照组给予等剂量生理盐水连续3个月灌胃处理;采用Morris水迷宫方法探测各组AD小鼠行为学改变、空间记忆及探索情况;免疫荧光染色检测各组小鼠海马组织突触后致密蛋白95 (PSD95)阳性表达水平;Western blotting(WB)法检测各组三转基因AD小鼠海马脑组织PSD95蛋白、磷酸化蛋白激酶B(p-Akt)和磷酸化雷帕霉素靶蛋白(p-mTOR)表达水平及微管相关蛋白轻链3-Ⅱ(LC3-Ⅱ)自噬水平.结果 AD+25 mgBBR组的逃避潜伏期的学习记忆能力、免疫荧光PSD95表达水平以及 PSD995、LC3-Ⅱ、p-Akt、p-mTOR蛋白表达水平与AD对照组比较均有明显差异(P<0.05);AD+50 mgBBR组逃避潜伏期的学习记忆能力、免疫荧光PSD95表达水平以及LC3-Ⅱ、p-Akt、p-mTOR表达水平与AD对照组比较差异均更明显(P<0.05,P<0.01).结论 应用50 mg小檗碱能较好改善三转基因AD小鼠的学习记忆、空间探索能力,其机制可能是通过增加自噬水平LC3-Ⅱ调控Akt/mTOR信号通路,增加突触蛋白PSD95的表达水平及突触数量,以改善AD相关临床症状.%Objective To expore the effect of berberine(BBR)on learning and memory and expression level of synaptic related protein(PSD95)in hippocampus of amyloid precursor protein/tau protein/presenilin-1 (APP/Tau/PS1)transgenic Alzheimer's disease(AD)mice.Methods 30 mice were divided into three groups according to the random number table method,namely AD control group,AD+25 mg BBR group,AD+50 mg BBR group.There were 10 rats in each group,then the later two groups were gavaged dosage of 25 mg· kg -1·d-1and 50 mg·kg -1·d-1for 3 months respectively.And the control group was given equal volume of nor-mal saline for 3 months.Morris water maze test was used to detect the behavioral changes of AD mice in each group.The expression level of PSD95 in hippocampus was detected by immunofluorescence staining.The ex-pression level of PSD95 protein as well as tube-associated protein 1 light chain 3(LC3)autophagy levels,p-Akt and p-mTOR protein levels were detected by Western blotting.Results There were significant differences between AD control group and AD model+25 mg dose BBR group in average scores,escape latency frequency through the original platform and dwell time percentages in the original platform quadrant in the traction exper-iments,positvie cell counts and average gray scale of PSD95,the expression protein level of PSD95、LC3-Ⅱ、p-Akt、p-mTOR(P<0.05).As compared with AD control group,the AD model+50mg dose BBR group showed more significantly different PSD95 protein LC3-Ⅱ、p-Akt、p-mTOR(P< 0.05,P< 0.01).Conclusion The 50mg-dose BBR application could better improve learning ability and memory capacity of the(APP/Tau/PS1) transgenic AD mice,whose mechanism might increase the autophagy level of LC3-Ⅱto regulate the Akt/mTOR signaling pathway,thereby increasing the expression level of synaptic-associated protein PSD95 and the num-ber of synapses to ameliorate AD-related clinical symptoms.