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

Effects of berberine on learning and memory and expression level of synaptic protein-related protein PSD95 in hippocampus of amyloid precursor protein/tau protein/presenilin-1 transgenic AD mice

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^-1 and 50 mg·kg^-1·d^-1 for 3 months respectively.And the control group was given equal volume of normal 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 expression level of PSD95 protein as well as tube-associated protein 1 light chain 3（LC3）autophagy levels,pAkt 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 experiments,positvie cell counts and average gray scale of PSD95,the expression protein level of PSD95、LC3-Ⅱ、pAkt、p-mTOR（P〈0.05）.As compared with AD control group,the AD model＋50 mg dose BBR group showed more significantly different PSD95 protein LC3-Ⅱ、p-Akt、p-mTOR（P〈0.05,P〈0.01）.Conclusion The50 mg-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 number of synapses to ameliorate AD-related clinical symptoms.