内皮素在脑缺血大鼠脑内激活的小胶质细胞中的表达

Expression of endothelins in the activated microglial cells following cerebral ischemia in the adult rats

目的：研究大鼠局灶性脑缺血后内皮素 （ETs） 在激活的小胶质细胞中的表达变化,探讨ETs与脑缺血的关系.方法：采用微创开颅法建立大鼠大脑中动脉闭塞 （MCAO） 模型,分为缺血组和假手术组.应用荧光双标和激光共聚焦显微镜观察脑缺血后小胶质细胞的变化及ETs在激活的小胶质细胞的表达变化;应用Real time PCR分析脑缺血后大脑皮层ETs mRNA的表达.结果： 在缺血中央区可见大量坏死细胞,在半暗区可见大量激活的小胶质细胞,以缺血后3d、1周数量最多,达高峰,正常灌注区小胶质细胞与对照组及缺血对侧脑组织相似,为静息状态的小胶质细胞.荧光双标染色可见激活的小胶质细胞与ETs免疫阳性细胞有共表达,静息状态的小胶质细胞则呈阴性.Real time PCR分析显示,缺血侧皮层ET-1 mRNA和ET-3 mRNA水平与对侧及假手术组皮层比较均升高,高峰分别在缺血后12h和2h.结论： 脑缺血后激活的小胶质细胞如胚胎时期和生后早期的阿米巴样小胶质细胞一样表达ETs,成为ETs的一个重要细胞来源,可能参与了脑缺血的病理过程.

Objective： To study the expression of endothelins （ETs） in the activated microglial cells after focal cerebral ischemia in adult rats. Methods： To establish the middle cerebral artery occlusion model in rats with minimally invasive open skull operation, the adult male rats were randomly divided into an ischemia group and a sham operation group. Fluorescence double-lableing staining technique and laser scanning confocal microscope were used to investigate the variation of microglial cells and the expression of endothelins in the activated microglial cells after focal cerebral ischemia in rats. Real-time PCR was used to analyse the expression of endothelins mRNA in cerebral cortex after focal cerebral ischemia. Results ： After focal cerebral ischemia, there were many necrotic ceils in the ischemic core; in the peri-infacted zones, a large number of activated microglia cells appeared, and reached the peak at 3 days or 1 week. Normal perfusion area was similar to the control group or contralateral brain tissue, having the resting state of microglia. The co-expression of actived microglial cells and endothelins immunoreactive ceils was showed by imrnunofluorescence double labeling. The real-time PCR study demonstrated that the level of ET-1 mRNA and ET-3 mRNA be significantly higher than that of contralateral cortex or the sham operation group, respectively reach the peak at 12 hours and 2 hours after ischemia. Conclusion： Just like amoeboid microglial cells in embryonic and early postnatal period, activated microglial cells also can express ETs after cerebral ischemia, which can be regarded as an important cellular source of ETs. It appears to play a central role in the pathological process of cerebral ischemia.