摘要目的 探讨浅低温对大鼠全脑缺血再灌注后酸敏感离子通道1a(ASIC1a)和2a(ASIC2a)的影响及在脑复苏作用中的潜在机制.方法 95只雄性SD大鼠随机数字表分为以下5组(n=19):假手术组(Ⅰ)、模型组(Ⅱ)、浅低温组(Ⅲ)、PcTX1组(Ⅳ)、浅低温+PcTX1组(Ⅴ).四血管阻塞法建立大鼠全脑缺血再灌注损伤模型,缺血15 min,再灌注即刻Ⅳ组和Ⅴ组侧脑室注射500 ng/ml PcTX1 6μl,其余组侧脑室注射等容量生理盐水.同时Ⅲ组和Ⅴ组于再灌注15 min内将直肠温度降至32～ 33℃,并维持6h,其余组维持直肠温度36～37℃.测定再灌注6h及24 h海马ASIC1a和ASIC2a蛋白水平、再灌注24 h海马ASIC1a和ASIC2a mRNA表达水平；观察再灌注24h海马CA1区病理改变；以及测定再灌注72 h大鼠脑含水量.结果 与Ⅰ组比,其余各组ASIC1a mRNA和蛋白的表达差异无统计学意义(P＞0.05)；与Ⅰ组比,其余各组ASIC2a mRNA和蛋白的表达均增高(P＜0.05)；与Ⅱ组和Ⅳ组比,Ⅲ组和Ⅴ组ASIC2a mRNA和蛋白的表达增高(P＜0.05)；与再灌注6h相比,再灌注24hⅡ、Ⅲ、Ⅳ和Ⅴ组ASIC2a蛋白表达均增高(P＜0.05)；与Ⅰ组比,Ⅱ、Ⅲ、Ⅳ和Ⅴ组CA1区锥体细胞数均减少(P＜0.01)；与Ⅱ组比,Ⅲ、Ⅳ和Ⅴ组CA1区锥体细胞数均增加(P＜0.01),尤以Ⅴ组效果最明显(P＜0.01)；与Ⅰ组比,Ⅱ、Ⅲ和Ⅳ组脑水含量均增加(P＜0.01)；与Ⅱ组比,Ⅲ、Ⅳ和Ⅴ组脑水含量均降低(P＜0.01),Ⅴ组降低最明显(P＜0.01).结论 浅低温减轻大鼠全脑缺血再灌注损伤可能与ASIC2a mRNA和蛋白表达上调有关,且浅低温联合PcTX1对缺血脑组织的复苏具有协同作用.

abstractsObjective To investigate the effects of mild hypothermia on the expression of ASIC1a and ASIC2a in the rat hippocampus following global cerebral ischemia-reperfusion,so as to speculate the underlying mechanisms of neuroresuscitation.Methods Ninety five male SD rats were randomly divided into five groups (n =19):sham operation group(Ⅰ),model group(Ⅱ),mild hypothermia group(Ⅲ),PcTX1 group(Ⅳ),mild hypothermia combined PcTX1 group(Ⅴ).Transient (15 min) global cerebral ischemia was induced by the four-vessel occlusion.PcTX1 (500 ng/ml) 6 μl were injected into lateral cerebral ventricle immediately after reperfusion in group Ⅳ and Ⅴ,while the equal volume of normal saline was injected into lateral cerebral ventricle immediately after reperfusion in the other three groups.At the same time,mild hypothermia after reperfusion was performed and lasted for 6 hours in group Ⅲ and Ⅴ,the rectal temperature was reduced to 32-33 ℃ within 15 min,while it was maintained at 36-37 ℃ by lamp in other three groups.Determination the expression of ASIC1a and ASIC2a protein at 6 h and 24 h of reperfusion,and the expression of ASIC1 a and ASIC2a mRNA at 24 h of reperfusion.Observe the pathomorphological changes of hippocampal CA1 neurons at 24 h of reperfusion.Detect the brain water content at 72 h of reperfusion.Results The difference in the expression of ASIC1a mRNA and protein among the groups was not changedsignificantly (P ＞ 0.05).Compared with group Ⅰ,the expression of ASIC2a mRNA and ASIC2a protein was up-regulated in other groups (P ＜ 0.05).It was significantly higher in group Ⅲ and Ⅴ than in group Ⅱ and Ⅳ (P ＜ 0.05).Compared to 6 h of reperfusion,the expression of ASIC2a protein was higher in group Ⅱ,Ⅲ,Ⅳ and Ⅴ respectively after 24 h of reperfusion.Compared to group Ⅰ,the number of pyramidal cells in CA1 region of hippocampus in group Ⅱ,Ⅲ,Ⅳ and Ⅴ were decreased at 24 h of reperfusion (P ＜0.01).Compared to group Ⅱ,the number of pyramidal cells in CA1 region of hippocampus in group Ⅲ,Ⅳ and Ⅴ were increased at 24 h of reperfusion (P ＜ 0.01) ; and compared to group Ⅲ and Ⅳ,the number of pyramidal cells at 24 h of reperfusion in group Ⅴ was significantly higher (P ＜ 0.01).Compared to group Ⅰ,the content of brain water in Ⅱ,Ⅲ and Ⅳ group were increased at 72 h of reperfusion (P ＜0.01).Compared to group Ⅱ,the content of brain water in group Ⅲ,Ⅳ and Ⅴ were decreased at 72 h of reperfusion (P ＜ 0.01).Giving mild hypothermia or PcTX1 could alleviant the damage in CA1 region of hippocampus,with the best effect in group Ⅴ,which administers PcTX1 combined mild hypothermia.Conclusion Mild hypothermia attenuates global cerebral ischemia-reperfusion of rat,which may up-regulate the expression of ASIC2a mRNA and protein.Mild hypothermia combined by PcTX1 could induce neuroresuscitation.