脑缺血再灌注大鼠皮质NMDA受体亚单位NR2A/B蛋白的表达变化

目的 采用免疫细胞化学技术，探讨急性脑缺血再灌注不同时间段大鼠脑顶皮质NMDA受体亚单位NR2A及NR2B蛋白的表达变化。方法 雄性Wistar大鼠70只,随机分成正常对照组、假手术对照组、脑缺血再灌注对照组；以颈动脉引流法行全脑缺血7min再灌注造模，术后分6h、24h、72h3个时间段取脑．脑组织恒冷箱连续冠状切片,免疫细胞化学ABC反应，图像分析系统行顶皮质Ⅰ区V层免疫阳性面积检测。结果 （1）麻醉及假手术可导致顶皮质NR2A、NR2B蛋白表达短暂增多，24h内恢复正常；（2）缺血再灌注后6h前后形成表达高峰,24h恢复正常，随后表达急剧减少，持续至72h以后。结论（1）脑缺血再灌注可导致顶皮质神经元NR2A、NR2B蛋白表达变化，且表达存在明显的时间依赖性；（2）缺血再灌注早期皮质NR2A、NR2B蛋白高度表达可能是导致迟发性神经元丢失的重要原因。

Alterations in protein expression of NMDA receptor subunits NR2A and NR2B during reperfusion after ischemia in the rat brain

Objective By immunohistochemistry and compute-assisted image analysis,We investigated the changes in protein expression of NMDA receptor subunits NR2A and NR2B levels in rat brain area 1 of parietal cortex during reperfusion after ischemia. Methods 70 male wistar rats were randomly divided into 3 groups:normal control group(n= 10),sham-ischemia group(n=30),cerebral ischemia-reperfusion group(n=30). Temporary cerebral ischemia-reperfusion injury model was established by using common carotid artery blood drainage method. Brain section was obtained by cryostat sectioning. The section was prepared for NR2A/B immunohistochemistry staining and was observed by optical microscope. Quantitate analysis was carried out for NR2A/B immunoreactive matter and stain area. Results (1)The expression of NR2A and NR2B protein in area of parietal cortex transitory and lightly increased after narcosis and sham-operated, but came back to the normal control level at 24h. (2)Dur-ing ischemia-reperfusion,the expression of NR2A and NR2B protein in area of parietal cortex is increased sharply at 6h, and fall back to the control level at 24h,then it reduced sharply at 72h. Conclusion The present results demonstrate that the sharply expression of NR2A and NR2B protein in brain at early reperfusion might be one of the mechanism for delayed brain ischemia reperfusion injury.