[Electroacupuncture improves learning and memory impairment and enhances hippocampal synaptic plasticity through BDNF/TRKB/CREB signaling pathway in cerebral ischemia-reperfusion injury rats].

To observe the effect of electroacupuncture on brain-derived neurotrophin factor (BDNF) / tyrosine kinase receptor B (TRKB) / cyclic adenosine monophosphate response element binding protein (CREB) pathway, synaptic plasticity marker protein and synaptic ultrastructure in the hippocampus of rats with learning and memory impairment induced by cerebral ischemia reperfusion (IR), so as to explore its mechanisms underlying improvement of cognitive impairment after stroke.SD rats were randomly divided into blank, sham operation, model, and EA groups, with 12 rats in each group. The model of IR was established by occlusion of the middle cerebral artery. EA (2 Hz/10 Hz, 1-3 mA) was applied to "Shenting" (GV24) and "Baihui" (GV20) for 30 min, once daily for 14 days. The neurological function was evaluated according to the Zea Longa's score criteria. Morris water maze test was used to detect the learning and memory function of the rats. Nissl staining was used to observe the pathological morphology of the hippocampus. Transmission electron microscopy was used to observe the ultrastructure of the syna-pse in the hippocampus, the synaptic gap width and postsynaptic dense substance (PSD) thickness were measured. Immunofluorescence staining was used to observe the positive expression levels of BDNF, PSD-95 and synaptophysin (SYN) in hippocampal CA1 region. The protein expression levels of BDNF, TRKB, CREB, PSD-95, and SYN in hippocampal tissue were detected by Western blot.Compared with the sham operation group, the neurological function score and escape latency (EL) were significantly increased (P<0.01), the times of crossing the original platform were decreased (P<0.01), the number of neurons in the CA1 area of the hippocampus was reduced, with incomplete morphology, widened synaptic gaps and significantly decreased PSD thickness (P<0.01), the positive expressions of BDNF, PSD-95, SYN and the protein expression levels of BDNF, TRKB, CREB, PSD-95, SYN were significantly decreased (P<0.01) in the model group. Compared with the model group, the neurological function scores and EL on the 12th and 13th day were decreased (P<0.01, P<0.05), the times of crossing the original platform were increased (P<0.01), the morphology of hippocampal CA1 neurons improved, the synaptic gaps was decreased (P<0.01), the PSD thickness was significantly increased (P<0.01), the positive expressions of BDNF, PSD-95, SYN, and the protein expression levels of BDNF, TRKB, CREB, PSD-95, SYN were increased (P<0.05, P<0.01) in the EA group.EA can alleviate cognitive impairment in IR rats, which may be related to its function in up-regulating the proteins of BDNF/TRKB/CREB pathway, promoting the expressions of synaptic plasticity marker proteins PSD-95 and SYN, thus improving the synaptic plasticity.目的：观察电针对脑缺血再灌注损伤学习记忆障碍模型大鼠海马中脑源性神经营养因子（BDNF）/酪氨酸激酶受体B（TRKB）/磷酸腺苷反应元件结合蛋白（CREB）通路蛋白、突触可塑性标志蛋白及突触超微结构的影响，探讨电针改善脑卒中后认知障碍的机制。方法：SD大鼠随机分为空白组、假手术组、模型组和电针组，每组12只。采用改良的Zea Longa线栓法构建并结合神经功能缺损评分筛选出脑缺血再灌注后学习记忆障碍大鼠模型。电针组予“神庭”“百会”电针治疗，30 min/次，1次/d，连续14 d。采用Zea Longa神经功能评分评价大鼠神经功能缺损程度，Morris水迷宫检测大鼠空间学习记忆能力，尼氏染色观察大鼠海马CA1区神经元形态，透射电镜观察海马CA1区突触超微结构并测量突触间隙宽度和突触后致密物（PSD）厚度，免疫荧光染色法观察海马CA1区BDNF、PSD-95、突触素（SYN）阳性表达水平，Western blot法检测海马组织BDNF、TRKB、CREB、PSD-95和SYN的蛋白表达水平。结果：与假手术组相比，模型组的神经功能评分显著升高（P<0.01），逃避潜伏期（EL）显著延长（P<0.01），穿越原平台次数显著减少（P<0.01），海马CA1区神经元数量减少、形态不完整，突触间隙增宽（P<0.01），PSD厚度显著减小（P<0.01），BDNF、PSD-95、SYN阳性表达显著降低（P<0.01），BDNF、TRKB、CREB、PSD-95和SYN蛋白表达水平显著降低（P<0.01）。与模型组相比，治疗后电针组的神经功能评分显著降低（P<0.01），在造模后的第12、13天EL显著缩短（P<0.05，P<0.01），穿越原平台次数显著增加（P<0.01），神经元形态改善，突触间隙缩窄（P<0.01），PSD厚度显著增大（P<0.01），BDNF、PSD-95、SYN阳性表达显著升高（P<0.05），BDNF、TRKB、CREB、PSD-95和SYN蛋白表达水平显著升高（P<0.05，P<0.01）。结论：电针可能通过上调BDNF/TRKB/CREB通路蛋白，促进突触可塑性标志蛋白PSD-95、SYN的表达，改善突触超微结构，增强突触可塑性，减轻脑缺血再灌注损伤大鼠的认知障碍。.