短暂脑缺血诱导大鼠海马PKC-ε膜转位及HSP70表达

Transient ischemia induced membrane translocation of PKC-ε and expression of HSP70 in rat hippocampus

目的探讨蛋白激酶C-ε(protein kinase C,PKC-ε)和热休克蛋白70(heat shock protein,HSP70)在脑缺血耐受形成过程中的作用。方法将80只大鼠分为短暂脑缺血组和假手术组(n=40),每大组根据取材时间又分为缺血后1 h、6 h、1 d、2 d、4 d 5个亚组(n=8)。应用大脑中动脉阻闭(middle cerebral artery occlusion,MCAO)方法和免疫印迹(western blot)技术观察大鼠短暂脑缺血20 min后海马神经细胞不同时间点PKC-ε膜转位及HSP70表达的变化。结果假手术组各时间点的PKC-ε与HSP70无明显变化。在短暂脑缺血组,缺血后1 h海马神经细胞胞质PKC-ε的含量开始下降,至1天达最低点,持续到4天;而胞膜PKC-ε的变化趋势相反,含量于6 h显著增高,1天达到高峰,持续到4天;短暂缺血1 h后HSP70的表达无明显增加,6 h增多明显,1天达最高,持续至4天均处于较高水平。结论短暂脑缺血诱导海马神经细胞PKC-ε膜转位和HSP70表达增加,可能是短暂脑缺血诱导缺血耐受的机制。

Objective To investigate the roles of PKC-ε and HSP70 in the formation of brain ischemic tolerance. Methods Middle cerebral artery occlusion （MCAO） model and Western blot analysis were used to observe the membrane translocation of PKC-ε and the changes in HSP70 expression in the hippocampal neurons at different time points （ 1 h, 6 h, 1 d, 2 d and 4 d after a 20 rain transient cerebral ischemia）. The results were compared with those of the sham - operation group. Results No significant changes in PKC - 8 and HSP70 were found in the sham - operation group. In the transient cerebral ischemic group, cytoplasm PKC - 8 began to decrease 1 h after treatment, reached its lowest level on 1 d and remained at such a level until 4 d ; while the membrane PKC - 8 tended to vary the opposite way ： i.e. the membrane PKC - 8 increased notably 6 h after transient ischemia, peaked on 1 d and remained high until 4 d. The expression of HSP70 began to increase obviously 1 h after transient ischemia, increased markedly at 6 h, peaked on 1 d and remained high until 4 d. Conclusion Transient ischemia induces membrane translocation of PKC - 8 and increases the expression of HSP70, which may be the genetic mechanism of ischemic tolerance induced by transient ischemia.