大鼠局部脑缺血再灌注后淀粉样前置蛋白基因的表达

Expression of Amyloid Precursor Protein Genes following Focal Cerebral Ischemia and Reperfusion in Rats

目的 检测大鼠局部脑缺血再灌注后淀粉样前置蛋白(APP)基因的表达情况。方法 选取SD大鼠136只,随机分为八组。采用线栓法制作右侧大脑中动脉(MCA)缺血再灌注模型。A组为对照组,B～H各组大鼠脑缺血1h后,分别再灌注0、1、3、8h和1、3、7d后处死。取双侧脑皮质,用RT-PCR方法检测APP770、APP751、APP695 mRNA的表达水平;应用Western印迹及免疫组化方法检测APP蛋白质的表达。结果 缺血再灌注后脑皮质含KPI结构区的APP770和APP751mRNA水平在再灌注1d后开始升高(P≤0.01),第3d达高峰后逐渐下降,第7d达基础水平。APP695 mRNA在缺血再灌注后第1d到第3d逐渐下降后回升(P≤0.01),直到第7d达基础水平。再灌注8h后神经变性开始出现,同时神经胶质酸性蛋白(GFAP)免疫阳性的星形细胞开始增多。结论 缺血再灌注损伤能诱发APP mRNA的表达升高;选择性诱发KPI-APP表达升高的原因可能是由于反应性星形细胞增多所致,调节APP剪切的一些因素也参与脑缺血病理过程。

Objective To elucidate amyloid precursor protein ( APP) gene expression in cerebral cortex following cerebral ischemia -reperfusion injuries. Methods Rats(n=136) were given an is-chemic insult through unilateral MCA occlusion and reperfusion by use of intralurainal suture, which was composed of 1 hour's occlusion and reperfusion for Oh, Ih, 3h, 8h, 1d, 3d, 7d, respectively. The rats were sacrificed and cerebral cortex was dissected. The mRNA levels of APP770,751,695 was investigated by RT - PCR. Also neuronal damage and glial fibrillary acidic protein immunohistochemistry were histologi-cally examined. Results After transient ischemia, the Kunitz protease inhibitor - bearing isoforms(KPI -APP) were increased whereas APP695 which lack KPI domain was decreased. Neuronal damage and GFAP immunoreactive astrocytes were also observed. Conclusion The results indicate that focal transient ischemia alters KPI - APP/APP695 ratio in cerebral cortex and this shift in APP isoforms could be related to neurodegeneration and /or activation of astrocytes during the ischemic process.