亚低温对大鼠短暂性全脑缺血后APE/Ref-1表达、神经元凋亡的影响

Effects of Hypothermia on apoptosis and the expression of APE/Ref-1 following transient forebrain ischemia in rat

关键词:  脑缺血  神经元  凋亡  亚低温  APE/Ref-1  DNA修复  大鼠

Key words:  cerebral ischemia  neuron  apoptosis  mild hypothermia  APE/Ref-1  DNA repair  rat

摘要:

[目的] 通过大鼠短暂全脑缺血模型来探讨亚低温对大鼠脑缺血后APE/Ref-1(apurinic/apyrimidimic endonuclase/redox factor 1, 无嘌呤/无嘧啶核酸内切酶/氧化还原因子-1)蛋白表达及缺血性神经元凋亡的影响,揭示亚低温的部分神经保护机制。[方法] 采用“双侧颈总动脉夹闭+低血压法”建立大鼠短暂性全脑缺血模型。实验动物分假手术组、手术后常温存活1 d、2 d、3 d 组及手术后亚低温存活1 d、2 d、3 d 组。用免疫组化方法检测各组APE/Ref-1蛋白的表达；用TUNEL染色观察全脑缺血后海马CA1区神经元凋亡的情况。[结果] 免疫组化显示假手术组神经元广泛表达APE/Ref-1蛋白。在10 min全脑缺血后的1 d时，海马CA1区APE/Ref-1阳性细胞开始减少，2 d时明显减少。该区TUNEL阳性细胞在缺血后2 d时出现，3 d时表现明显。亚低温缺血组APE/Ref-1蛋白表达下降程度较常温缺血组明显减轻（P<0.01）且时间推迟；神经元凋亡出现的时间亦比常温缺血组迟，且凋亡数较常温组少（P<0.01）。APE/Ref-1和TUNEL双重染色提示丧失了APE/Ref-1免疫活性的细胞转变为TUNEL阳性细胞。[结论] 亚低温对缺血后神经元具有保护作用，其机制可能为抑制缺血后APE/Ref-1下降，及减少神经元凋亡。

Abstract:

[Objective] To explore the neuroprotective mechanism of mild hypothermia by studying the effects of mild hypothermia on the expression of APE/Ref-1 and neuronal apoptosis in the hippocampal CA1 subregion after transient global cerebral ischemia in rats. [Methods] A model of transient global cerebral ischemia was made by 10min of bilateral common carotid artery occlusion and hypotension in rat. Expression of the APE/Ref-1 protein was detected by immunohistochemical analysis. Apoptosis after global ischemia was observed with TUNEL. [Results] Immunohisto-chemistry showed the nuclear expression of APE/Ref-1 in the control brains. Nuclear decreasing immunoreactivity of APE/Ref-1 started at 1st day and became significantly at 2nd day and the TUNEL positive neurons were observed at 2nd day and became significant at 3rd day in the hippocampal CA1 subregion after transient global ischemia in normothermic group. Mild hypothermic ischemic group was less decreased in nuclear immunoreactivity of APE/Ref-1 (P<0.01) and less quantity of apoptotic neurons(P<0.01) than those of normothermic group . Double staining with APE/Ref-1 and TUNEL clearly showed that the neurons which lost APE/Ref-1 immunoreactivity became TUNEL positive. [Conclusions] The mild hypothermia had remarkable neuroprotection action. The inhibition of APE/Ref-1 reduction and ischemic neuronal apoptosis were assumed to be a neuroprotective mechanism of mild hypothermia.