亚低温减轻沙土鼠海马前脑缺血再灌注损伤和对Hsp70表达的影响

Mild hypothermia alleviating hippocampal CA1 regions forebrain ischemia-reperfusion injury in gerbils and its effects on the expression of Hsp70

目的观察亚低温(维持沙土鼠鼓膜温度在33℃,持续4h)对前脑缺血再灌注后沙土鼠海马CA1区细胞损伤和热休克蛋白70(Hsp70)表达的影响,研究亚低温减轻脑损伤可能的机制。方法采用沙土鼠前脑缺血再灌注损伤模型:双侧颈总动脉阻断5min。随机分为假手术组(SH组),假手术低温组(HSH组),再灌注常温组(IR组),再灌注低温组(HIR组),根据再灌注的不同时间点(2h、4h、1d、3d、5d)每组又分为5个对应的亚组(每亚组n=6)。在预定时间点行行为学检查,原位末端转移酶标记法(TUNEL)检测海马CA1区的凋亡细胞,免疫组化检测Hsp70在海马CA1区的动态变化。结果亚低温处理4h可减轻缺血沙土鼠的行为学异常,减少海马CA1区的凋亡细胞,促进Hsp70蛋白1d后的表达。结论 4h亚低温增加沙土鼠5min前脑缺血再灌注后海马CA1区Hsp70的表达,可能是其减少凋亡细胞产生脑保护作用的机制之一。

Objective To explore the effects of mild hypothermia （ keep the temperature of gerbil eardrum at 33 ℃ for 4 hs） on hippocampal CA1 regions cell injuries in gerbils after forebrain ischemia-reperfusion and the expressions of Hsp70,and detect the possible mechanism of mild hypothermia alleviating brain injury. Methods The experimentation adopted gerbil forebrain ischemia reperfusion injury model induced by 5 rain of obstruction in bilateral common carotid artery. The gerbils were randomly divided into 4 groups： sham group（SH）,hypothermia sham group （HSH）,normothermic ischemic reperfusion group （IR） and hypothermic ischemic reperfusion group （HIR）. Then the animals were designated as subgroups 2 h,4 h, 1 d, 3 d,and 5 d （n = 6 in each） at different time spots after ischemia. Behavioral studies were conducted at predetermined time points. The apoptotic cells in CA1 region were detected by TUNEL method. The variation of Hsp70 in CA1 region was detected by SP immunocytochemical technique. Results The abnormal behaviors and the number of apoptotic cells in hippocampal CA1 region were much less in HIR group than in IR group （P〈0.01） after 4 h of mild hypothermia. The expression of Hsp70 increased in HIR group compared with that in IR group after 1 d（P〈0.01）. Conclusion 4 h mild hypothermia could increase the expression of Hsp70 in gerbils CA1 region after forebrain iscbemia-reperfusion,and it may be one of the mechanisms that reduce apoptotic cells and protect the brain.