电针“百会”“涌泉”对APP/PS1双转基因小鼠海马突触可塑性相关蛋白表达的影响

Effects of electroacupuncture at “Baihui” and “Yongquan” on the levels of synaptic plasticity related proteins postsynaptic density-95 and synaptophysin in hippocampus of APP/PS1 mice

目的:从β-淀粉样蛋白(Aβ)对突触的毒性作用和突触可塑性的角度探讨电针在阿尔茨海默病病理前期改善学习记忆能力的机制。方法:将12只4月龄雄性APP/PS1转基因小鼠随机分为电针组和模型组,每组6只;以6只4月龄雄性C57BL/6小鼠作为正常组。电针组针刺"百会""涌泉"穴,双侧"涌泉"穴接电针,每次电针15 min,每周3次,连续6周。采用免疫荧光法观察小鼠左侧海马Aβ阳性表达水平,免疫组织化学法观察小鼠左侧海马突触后致密物-95(PSD-95)的阳性表达,Western blot法检测小鼠右侧海马PSD-95和突触素(SYN)的蛋白表达水平。结果:免疫荧光结果显示,模型组和电针组海马区可见细胞外的Aβ,但未见团状老年斑;与正常组比较,模型组海马区Aβ表达水平显著增加(P<0.01);与模型组比较,电针组海马区Aβ表达水平减少(P<0.05)。免疫组织化学结果显示,与正常组比较,模型组左侧海马区PSD-95阳性表达减少(P<0.05);与模型组比较,电针组左侧海马区PSD-95阳性表达增加(P<0.05)。Western blot结果显示,与正常组比较,模型组右侧海马区PSD-95、SYN的表达水平降低(P<0.05,P<0.01);与模型组比较,电针组右侧海马区PSD-95、SYN的表达水平增高(P<0.05,P<0.01)。结论:电针可以降低APP/PS1小鼠海马内Aβ的表达水平、升高PSD-95和SYN表达水平,提示电针可能通过降低海马内Aβ表达,减少Aβ对突触的毒性作用,从而改善其突触可塑性。

Objective From the perspective of β-amyloid(Aβ) toxicity and synaptic plasticity, the mechanism of electroacupuncture to improve learning and memory ability in the early pathological stages of Alzheimer’s disease was explored. Methods Twelve male amyloid-protein precursor(APP)/γ-secretase(PS1) double transgenic AD mice were randomly and equally divided into electroacupuncture(EA) group and model group, and other 6 male C57 BL/6 mice were used as the normal group. EA(1 Hz/50 Hz, 0.5 mA) was applied to "Baihui"(GV20) and bilateral "Yongquan"(KI1) for 15 min, once every other day for 6 weeks. Immunofluorescence was used to observe the positive expression of Aβ in the left hippocampus. Immunohistochemistry was used to observe the positive expression of postsynaptic density-95(PSD-95) in the left hippocampus. Western blot was used to detect the expression of PSD-95 and synaptophysin(SYN)in the right hippocampus. Results Immunofluorescence results showed that extracellular Aβ was seen in the model group and electroacupuncture group, but no senile plaques were seen. Compared with the normal group, the expression level of Aβ in the hippocampus of the model group increased significantly(P<0.01). Compared with the model group, the expression of Aβ in the hippocampus of the EA group decreased(P<0.05). Immunohistochemical results showed that compared with the normal group, the PSD-95 positive expression in the model group was decreased(P<0.05). Compared with the model group, the expression of PSD-95 in the EA group was increased(P<0.05). Western blot results showed that compared with the normal group, the expression levels of PSD-95 and SYN in the hippocampus of the model group were decreased(P<0.05, P<0.01). Compared with the model group, the expression levels of PSD-95 and SYN in the EA group were increased(P<0.05,P <0.01). Conclusion EA can reduce the expression of Aβ in the hippocampus of APP/PS1 mice and increase the expression of PSD-95 and SYN, which may contribute to its effect in improving the synaptic plasticity.