Objective: To observe the effect of electroacupuncture (EA) of "Xiusanzhen" ［bilateral "Yingxiang"(LI20)+"Yintang"(GV24+)］ on synaptophysin (SYN), postsynaptic density protein-95 (PSD-95), Iba-1+ CD68+ microglia and complement C related protein expression of hippocampus in Parkinson's disease dementia (PDD) mice, so as to explore its mechanism in improving memory impairment of PDD.
Methods: Male C57BL/6 mice were randomly divided into control, sham operation, model and EA groups, with 10 mice in each group. The PDD model was established by injecting 6-OHDA into the medial forebrain tract. EA (2 Hz, 1 mA) was applied to unilateral LI20 and GV29 for 20 min once daily for consecutive 14 days. Morris water maze and new object recognition test were used to evaluate the learning and memory ability. Western blot was used to detect the expression of SYN and PSD-95 proteins in hippocampus. Immunofluorescence was used to label Iba-1+ CD68+ microglia and C1q positive cells in hippocampal CA1 region. The content of C3 protein in hippocampus was detected by ELISA.
Results: Compared with the control group, there was no statistical significance in all the observed indexes in the sham operation group. Compared with the sham operation group, the average escape latency (AEL) prolonged significantly (P<0.01), the target platform crossing times (TPCT) and new object recognition index (NORI) decreased remarkably (P<0.01); the expressions of SYN and PSD-95 proteins in hippocampal CA1 region were significantly decreased (P<0.01); the rate of Iba-1+CD68+ microglia, the rate of C1q positive cells and the content of C3 protein were significantly increased (P<0.01) in the model group. In comparison with the model group, the AEL was shortened (P<0.01), the TPCT and NORI were increased (P<0.05) remarkably; the expressions of SYN and PSD-95 proteins in hippocampal CA1 region were increased (P<0.01, P<0.05); the rate of Iba-1+ CD68+ microglia, the rate of C1q positive cells and the content of C3 protein were significantly decreased (P<0.01) in the EA group.
Conclusion: "Xiusanzhen" can alleviate the learning and memory impairment of PDD model mice, and improve the synaptic plasticity of hippocampal CA1 area. The mechanism may be related to the reduction of C1q and C3 deposition in hippocampal CA1 region and the reduction of microglia phagocytosis.
目的：观察电针干预对帕金森病痴呆(PDD)模型小鼠海马CA1区突触素(SYN)、突触后密度蛋白95(PSD-95)、离子钙结合接头分子1(Iba-1)+CD68+小胶质细胞数及补体（C）相关蛋白表达的影响，探讨“嗅三针”改善PDD记忆障碍的部分作用机制。方法：雄性C57BL/6小鼠随机分为空白组、假手术组、模型组和电针组，每组10只。采用单侧内侧前脑束注射6-羟多巴胺建立PDD小鼠模型。电针组予“嗅三针”电针干预，每日1次，每次20 min，连续14 d。采用Morris水迷宫及新物体识别实验评估各组小鼠学习记忆能力；Western blot法检测海马CA1区SYN、PSD-95蛋白的表达量；免疫荧光法标记海马CA1区Iba-1+ CD68+小胶质细胞及C1q阳性细胞并计算阳性细胞率；ELISA法检测海马CA1区C3蛋白含量。结果：与空白组比较，假手术组各指标差异均无统计学意义（P>0.05）。与假手术组比较，模型组小鼠逃避潜伏期延长(P<0.01)，穿越原平台次数、新物体识别认知指数（NORI）降低(P<0.01)；与模型组比较，电针组小鼠逃避潜伏期缩短(P<0.01)，穿越原平台次数、NORI升高(P<0.05)。与假手术组比较，模型组小鼠海马CA1区SYN、PSD-95蛋白表达量显著降低(P<0.01)，Iba-1+ CD68+小胶质细胞率、C1q阳性细胞率及C3蛋白含量显著升高(P<0.01)；与模型组比较，电针组小鼠海马CA1区SYN、PSD-95蛋白表达量升高(P<0.01, P<0.05)，Iba-1+ CD68+小胶质细胞率、C1q阳性细胞率及C3蛋白含量显著降低(P<0.01)。结论：“嗅三针”可缓解PDD模型小鼠学习记忆障碍，改善海马CA1区突触可塑性，其机制可能与减少海马CA1区C1q、C3表达，降低小胶质细胞吞噬能力有关。.
Keywords: Complement 1q; Complement 3; Electroacupuncture; Microglia; Parkinson’s disease dementia; Synapse.