丰富环境对脑缺血大鼠突触界面结构修饰和PSD-95基因表达的影响

The Effects of Enriched Environment on Structural Modification of Synaptic Interface and PSD-95 mRNA of Rats after Transient Focal Cerebral Ischemia

探讨丰富环境干预对局部脑缺血大鼠突触界面结构修饰和突触后致密物-95 (postsynaptic density-95，PSD-95 ) mRNA表达的影响。栓塞健康雄性Sprague-Dawley大鼠的右侧大脑中动脉，建立脑中动脉栓塞(middle cerebral artery occlusion，MCAO)模型后，分为丰富环境缺血组(IE)、标准环境缺血组(IS)，同时分别设丰富环境假手术组(SE)、标准环境假手术组 (SS)。以Morris水迷宫检测大鼠的空间学习记忆能力，应用透射电镜、图像分析和细胞形态计量学技术，观察海马CA1区和额叶皮层突触界面结构变化，采用RT-PCR检测突触后脚手架蛋白PSD-95 mRNA的表达。结果表明：丰富环境干预能有效改善脑缺血导致的空间学习记忆能力下降，并对正常大鼠的空间学习记忆能力也有改善作用。同时，丰富环境干预能抑制局部脑缺血导致的突触数密度减少，该作用对额叶皮层特别明显；丰富环境干预不同程度地逆转脑缺血造成的突触界面参数变化，特别使突触间隙宽度显著减小、PSD厚度明显增加；并有效抑制因脑缺血诱导的PSD-95 mRNA表达下调。以上结果提示，丰富环境改善脑缺血大鼠的空间学习记忆能力可能与其促进缺血区边缘组织突触界面结构修饰，提高PSD-95 mRNA表达有关。

Reports have shown that damage to the adult brain can result in adaptive changes in regions adjacent to or surrounding the site of the principal injury， and that these changes may be modulated by rehabilitation training. An enriched environment has been shown to improve the cognitive， behavioral， and histopathological outcomes following focal cerebral ischemia and head trauma. Morphological changes in areas adjacent to the injury site have been reported following damage to the adult brain. In tr