+Gz诱导热休克蛋白表达及其对+Gz致脑损伤保护作用的研究

Expression of Heat Shock Protein after +Gz Exposure and Its Protective Effects on +Gz-induced Brain Injury

目的探讨不同 +Gz重复暴露后 ,大鼠不同脑区HSP70表达强度和时程的变化规律 ,及其与正加速度致脑损伤的相关性。方法将雄性SD大鼠随机分为对照组、+ 2Gz、+ 4Gz、+ 6Gz、和 + 1 0Gz暴露组。分别在暴露后 6h ,1 0h ,1d ,2d ,4d和 6d处死取脑 ,观察HSP70和HSP70mRNA在鼠脑不同部位的表达以及脑神经元形态学的变化。结果低G值 ( + 2Gz)下 ,HSP70表达强度弱 ,持续时间短 ,但范围较广 ;高G值 ( + 1 0Gz)下 ,表达仅局限在下丘脑部位 ,呈中等强度反应 ;中等强度G值 ( + 4Gz和 + 6Gz)下 ,表达范围广 ,持续时间长。各组表达峰值均在暴露后 1d左右 ,但暴露 1次组 2d后强度明显减弱 ,而暴露 3～ 5次组在 2d后仍然维持较高水平。不同 +Gz暴露后HSP70mRNA的表达在分布上与蛋白表达无明显变化 ,但其表达高峰提前 ( 1 0h) ,持续时间缩短。直接 + 1 0Gz/5min暴露后 ,在皮层、海马、丘脑等部位均可见到变性的神经元。而经过 + 4Gz/3min 3次和 5次预暴露再作 + 1 0Gz/5min暴露组 ,变性神经元的数目在顶叶皮层、梨状皮层、海马和丘脑下部等部位明显减少。结论 + 4Gz和 + 6Gz诱导的HSP70表达比 + 2Gz和 + 1 0Gz诱导的HSP70表达强 ,持续时间也长。 + 4Gz/3min反复暴露 3次和 5次 ,再暴露于 + 1 0Gz/5min ,其神经元损伤程度明?

Objective To investigate the rule of intensity and duration of HSP70 expression in rat brain and its relationship with brain injury after repeated +Gz exposures. Method SD male rats were aranged into control group, +2 Gz, +4 Gz, +6 Gz,and +10 Gz exposure groups. Rat brains were taken 6 h, 10 h, 1 d, 2 d, 4 d or 6 d after +Gz exposure for histopathologic and immunohistochemic or in situ hybridization studies. The expression of HSP70 and HSP70 mRNA or morphology of neurons were observed. Result The intensity and duration of HSP70 expression were weak and brief at +2 Gz exposure, but was relatively extensive. There was a middling reaction of HSP70 only in hippocampal area after +10 Gz exppossure. The duration, extension and intensity of HSP70 expression were wide, long and strong after +4 Gz and +6 Gz exposures. After 1 or 3～5 times exposures, the HSP70 expression reached its peak on the first day after +4 Gz exposures, and dropped obviously on the second day.However the expression of HSP70 maintained a high level after 2 d and was still higher than normal on the 6 d after 3～5 times repeated +4 Gz exposures. The distribution of HSP70 mRNA expression was as same as that of the HSP70 expression but the peak appeared much earlier(10 h) and its duration was shorter. After +10 Gz/5 min exposure,degenerated neurons were found in cortex, hippocampus and thalamus regions while the number of degenerated neurons were obviously decreased in such areas in pre exposure groups with repeated +4 Gz/3 min for 3～5 times. Conclusion The intensity and duration of HSP70 and HSP70 mRNA expression after +4 Gz and +6 Gz exposure were stronger and longer than +2 Gz and +10 Gz exposure. The degree of neuron damage after +10 Gz/5 min exposure in pre exposure groups with repeated +4 Gz/3 min 3～5 times was obviously slight comparing with that of single +10 Gz exposure group.