脑血流低灌注对大鼠突触后致密物结构及PSD-95蛋白表达的影响

The influence of cerebral hypo-perfusion on postsynaptic density structure and postsynaptic density-95 protein expression in rats

目的研究脑血流低灌注对大鼠学习记忆、脑组织突触后致密物(postsynaptic density,PSD)超微结构及PSD-95蛋白表达的影响。方法利用双侧颈总动脉永久性结扎制备SD大鼠脑血流低灌注模型。将SD大鼠随机分为假手术组和脑血流低灌注模型组。采用Morris水迷宫检测大鼠学习记忆情况。采用透射电镜结合Image Pro Plus图像分析系统定量分析大鼠海马突触数量、PSD长度和厚度。采用免疫组化观察大鼠脑组织PSD-95的表达。结果脑血流低灌注大鼠空间参考记忆及工作记忆能力减退,在第2至4天游泳训练时间段,搜寻隐藏平台路径较假手术组明显增加(P<0.05);撤离平台后,在原平台象限游泳时间及路径较假手术组降低,准确穿越原平台所在位置次数减少(P<0.05);当平台移动到第Ⅱ、Ⅳ象限时,搜索移动平台路径较假手术组明显延长(P<0.05)。与假手术组比较,脑血流低灌注大鼠海马突触数量明显减少,PSD长度变短,厚度变薄(P<0.05);海马CA1区、丘脑前内侧核、颞叶皮层PSD-95积分吸光度降低(P<0.05)。结论脑血流低灌注所致学习记忆功能减退与海马突触后致密物结构损伤、PSD-95蛋白表达下降有关。

Objective To observe the influence of cerebral hypo-perfusion on the learning and memory ability of rats,and the ultrastructure of postsynaptic density（PSD）and PSD-95 protein expression changes.Methods SD rats were randomly divided into sham-operated group and cerebral hypo-perfusion group.The cerebral hypo-perfusion model was produced by permanent bilateral common carotid artery ligation.Learningmemory function examination was assessed by Morris water-maze.The number of synapses,length and thickness of PSD were analyzed by means of transmission electron microscopy combined with Image Pro Plus image analysis system.PSD-95 expression in brain of rats＇ tissues was observed by immunohistochemical staining.ResultsThe swim distance for searching the hidden platform was obviously longer in cerebral hypo-perfusion group（P〈0.05）in comparison with sham-operated group in the first 2-4days of swimming training period.After the withdrawal of the platform,the time and swim distance of cerebral hypo-perfusion group were less than the shamoperated group in the target quadrant.The frequency of going through the platform correctly also decreased in cerebral hypo-perfusion group（P〈0.05）.When the platform was moved to the second and third quadrant,the distance for searching the moving platform was obviously longer in cerebral hypo-perfusion group compared with sham-operated group（P〈0.05）.The number of hippocampal synapses also reduced significantly in cerebral hypo-perfusion group.The activity length and thickness of PSD were obviously decreased in cerebral hypoperfusion group（P〈0.05）.The integrated optical density of PSD-95 in hippocampal CA1 region,anteromedial thalamic nucleus and temporal cortex were significantly decreased in cerebral hypo-perfusion group.ConclusionsCerebral hypo-perfusion can lead to learning-memory dysfunction;it is related to the damage of postsynaptic dense structure and the decrease of PSD-95 expression.