沙土鼠脑缺血后海马CA1区神经细胞凋亡、相关基因表达及亚低温的干预作用

目的 研究沙土鼠脑缺血后海马CA1区神经细胞凋亡、相关基因表达及亚低温的干预作用. 方法 72只沙土鼠采用随机数字表法分为假手术组(SH)、低温假手术组(HSH)、常温再灌注组(IR)和低温再灌注组(HIR).采用双侧颈总动脉阻断5 min制作脑缺血再灌注损伤模型,各组依术后处死动物时间的不同再分为1、3、7d亚组(n=6),在预定时间点行开阔法迷宫检查、TUNEL法检测海马CA1区神经细胞的凋亡、免疫组化检测肿瘤抑制基因p53、核因子-kB的表达情况.结果 常温状态下脑缺血5 min可诱导沙土鼠1、3、7d的探索活动增加(P<0.051.亚低温状态下仅缺血再灌注后1 d探索活动增加(P<0.05);TUNEL与免疫组化染色显示海马CA1区神经细胞凋亡数量及p53蛋白和NF-KB表达增加,亚低温对以上过程有明显抑制作用(P均<0.05). 结论 海马CA1区p53蛋白和NF-KB表达增加可能是沙土鼠脑缺血5 min神经元凋亡的机制之一,亚低温脑保护机制可能与其对此过程的抑制作用有关.

Neuronal apoptosis and apoptosis-related gene expression in the hippocampai CA1 region following cerebral ischemia in gerbils and their changes after intervention with mild hypothermia

Objective To study the neuronal apoptosis and expressions of apoptosis-related genes in the hippocampal CAI region after cerebral ischemia in gerbils and investigate the protective effects of mild hypothermia. Methods Seventy-two gerbils were randomized equally into sham-operated group, hypothermic sham-operated group, normothermic ischemia-reperfusion (IR) group and hypothermic IR groups, and 5-minute forebrain iscbemia was induced in the latter 2 groups by bilateral common carotid artery obstruction. Normothermic or mild hypothermic condition was applied to the groups after the operation as indicated. At 1, 3 and 7 days after the operation, 6 gerbils were selected from each group for behavioral test using open field test, followed by detection of neuronal apoptosis in the hippocampal CAI region using TUNEL staining and by immunohistocheraistry for p53 and nuclear factor-kB (NF-kB) expressions. Results In normothermic condition, the 5-minute forebrain ischemia induced significant enhancement of the exploratory activities in the gerbils 1, 3 and 7 days after the operation (P<0.05). This enhancement was observed only 1 day after the operation in mild hypothennic condition (P<0.05). Increased neuronal apoptosis and up-regulated expressions of p53 protein and NF-kBin the hippocampal CA1 region occurred after the forebrain ischemia as shown by TUNEL staining and immunohistochemistry, and all these changes were significantly inhibited by the application of mild hypothermia (P<0.05). Conclusions Up-regulated p53 and NF-kB protein expression in the hippocampal CA1 region might be one of the mechanisms for ischemia-induced neuronal apoptosis in gerbils, and mild hypothermia may produce protective effects against these changes for brain protection following the iscbemia.