局部脑缺血预处理对大鼠脑梗死的影响和HSP70的表达及mRNA的变化

目的建立局灶性可重复性大鼠脑缺血动物模型,研究短暂性局部脑缺血后再灌注不同时间对大脑中动脉阻塞(MCAO)的影响。方法应用改进的Longa's法,建立阻断左侧中动脉的局部脑缺血预处理模型。各组大鼠均经两次处理预处理(PC)组大鼠20min短暂脑缺血,分别在再灌注12h、1d、3d、5d、7d、14d后,造成MCAO;脑梗死组大鼠只在第二次处理造成大脑中动脉闭塞;短暂缺血组只在第一次处理时缺血20min,各组大鼠均在第二次处理后24h断头处死,检测以下指标神经功能缺失评分;TTC染色测量梗死范围HE染色观察组织结构变化;免疫印迹(原位杂交)和免疫组织化学染色观察HSP70的表达。结果PC后1d、2d、3d、5d、7d组与脑梗死组相比较,脑梗死范围,梗死周边区脑组织的缺血性损伤明显减轻了;短暂性脑缺血引起了轻微的神经细胞结构的改变并使缺血区HSP70的表达增加,MCAO后24hHSP70蛋白在缺血周边区出现了广泛表达。结论短暂局部缺血预处理可以诱导脑梗死后脑组织产生缺血耐受性,其保护作用出现再灌注后l~7d;缺血预处理引起HSP70的变化与缺血耐受的产生有一定联系。

Protective effects of focal ischemical preconditioning and HSP70 expression on middle cerebral artery occlusion in rats

Objective: To investigate the protective effect of a short duration focal ischemia on the subsequent middle cerebral artery occlusion(MCAO) of the transient ischemia in rat brain. Methods:Temporary MCAO (20 minutes) was used for PC (ischemic precondioning),.Various periods of repeffusion (ic, 12 hours and ld,3, 5, 7, and 14days) were allowed after PC and before permanent MCAO (PMCAO) (n=5 per group) establish ischemic tolerance (IT) compared with non-PC (sham- operated) rats (n=5 per group). Infarct size, neurological deficits were measured after PMCAO. The hitological damage was evaluated by HE staining. The expression of HSP70 was analyzed by in situ hybridization and immunohistoehemistry at 12h, 1, 3, 5, 7, and 14 adys after PC or non-PC before PMCAO. Results: Hemispheric infarct was significantly (P<0.01= reduced only if PC was performed lday (decreased 53.2%), 3days (decreased 55.8%), 5 days(decreased 53.9%), 7 days (decreased 56.1%) before PMCAO. PC significantly (P<0.01) reduced neurological deficits (similar to reductions in infarct size). PC produced no brain injury but did increased HSP70 gene and protein at 1, 3, 5, and 7days. HSPT0 expression was greatly enhanced in penumbra area after PMCAO. Conclusions: The results suggest that PC is a powerful inducer ofisehemic brain tolerance as reflected preservation of brain tissue and motor function. The protective effects occur after 1 day and last for 7days, meanwhile ,we found that PC increase HSP70 expression in after I day and last for 7days, which indicate that the protective mechenism of PC associate with upregulation of the ptotein in cells in ischemic region