电针对局灶性脑缺血大鼠缺血区突触结构的影响

Effect of electroacupuncture on the synaptic structure in the ischemic areas of rats with focal cerebral ischemia

目的:探讨针刺对缺血性脑损伤后的突触可塑性促进作用的机制。方法:36只SD大鼠分为假手术2、5周,缺血2、5周,缺血+针刺2、5周共6个组,采用热凝闭大鼠大脑中动脉致局灶性脑缺血模型,研究缺血2和5周后缺血区皮质突触超微结构的变化规律和针刺对其影响。结果:造模后突触的面数密度(Nv)、突触连接带面密度(Sv)和突触后膜致密物质(PSD)显著下降。缺血5周组大鼠缺血脑区Nv,Sv为(0.879±0.104)个/μm3,(0.082±0.003)μm2/μm3,均多于缺血2周组(0.489±0.122),(0.038±0.002)μm2/μm3;其中Sv和PSD在电针治疗2和5周时均显著上升,而Nv,在电针治疗5周时才显著增加(P<0.05);造模后突触的体密度和突触界面曲率数值都会显著减少(P<0.05),电针似不能提高这两个指标的数值。结论:提示电针可以保护与改善脑缺血模型大鼠皮质的神经突触结构,为电针促进缺血性脑损伤后的恢复提供了有力的物质形态学基础。

AIM: To investigate the mechanism for electroacupuncture in improving the plasticity of synapse after ischemic brain injury. METHODS: Totally 36 SD rats were divided into 6 groups: sham operated 2 and 5 weeks groups, ischemia 2 and 5 weeks groups, ischemia+electroacupuncture 2 and 5 weeks groups. Models of focal cerebral ischemia were established by heat coagulating occlusion of the middle cerebral artery .The changing rules of synaptic ultrastructure in the ischemic cortex were studied 2 and 5 weeks after ischemia, and the influence of electroacupuncture was also investigated. RESULTS: There were significant decreases in the number density(Nv) of synapse, surface density(Sv) of synaptic joining band and postsynaptic densities (PSD) after establishment of models. The Nv and Sv in the ischemic area of rat brain in the ischemic 5 weeks group[(0.879±0.104)/μm3,(0.082±0.003)/μm3] were higher than those in the ischemic 2 weeks group [(0.489±0.122) /μm3, (0.038±0.002)/μm3]. The Sv and PSD were significantly increased 2 and 5 weeks after electroacupuncture therapy, while the Nv was significantly increased 5 weeks after electroacupuncture therapy (P< 0.05). The volume density (Vv) and the curve rate of synaptic surface were significantly decreased after establishment of model(P< 0.05), which could not be increased by electroacupuncture. CONCLUSION: Electroacupuncture can protect and improve the synaptic structure in the cortex of rat model of cerebral ischemia, and provide powerful substantial morphological basis for the improvement of recovery after ischemic brain injury by electroacupuncture.