亚低温对大鼠短暂全脑缺血后神经元凋亡的影响

目的 探讨亚低温对大鼠脑缺血后神经元凋亡的影响，揭示亚低温的部分神经保护机制。方法 采用“双侧颈总动脉阻断＋全身低血压”方法来建立大鼠短暂性全脑缺血模型。用神经元尼氏体亚甲兰特殊染色法观察大鼠脑缺血后海马CA1区神经元损害情况；原位细胞凋亡检测法（TUNEL染色）及电镜观察脑缺血后CA1区神经元凋亡情况。结果 与假手术组、低温缺血组相比，常温缺血组海马CA1区神经元缺失明显（P＜0．01）。常温及低温缺血组海马CA1区均存在神经元凋亡，但低温缺血组海马CA1区凋亡神经元数明显少于缺血组（P＜0．01）。结论 经“双侧颈总动脉阻断＋全身低血压”方法建立的大鼠短暂全脑缺血模型证实了亚低温的脑保护作用。全脑缺血后的迟发性神经元死亡很可能经由凋亡途径，而亚低温可通过抑制缺血性神经元凋亡而发挥一定的神经保护作用。

Effect of mild hypothermia on neuronal apoptosis after transient global cerebral ischemia in rats

Objective To explore the neuroprotective mechanism of mild hypothermia by studying the effect of mild hypothermia on neuronal apoptosis after transient global cerebral ischemia in rats.Methods A model of transient global cerebral ischemia was made by bilateral common carotid artery occlusion and hypotension in rats. The neuronal demage in the CA 1 section of the hippocampus after cerebral ischemia was observed by nissel body stain mothed;apoptosis was detected by in situ end-labeling of fragmented DNA using the terminal deoxynucleotidyl transferase reaction (TUNEL) and the electrical microscope.Results The hippocampal CA 1 section neurons in normothermic ischemic group were significantly deficit as compared with the false operative group in mild hypothermic ischemic group (P< 0.01).The neuronal apoptosis in hippocampal CA 1 section was found in both normothermic and hypothermic ischemic groups, the quantity of apoptotic neurons in mild hypothermic ischemic group in hippocampal CA 1 section was decreased compared with that of the normothermic group (P<0.01).Conclusion The model of transient global cerebral ischemia made by bilateral common carotid artery occlusion and hypotension in rats was fit this study. With this model, the neuroprotection of hypothermia was confirmed. The delayed neuronal deaths after global cerebral ischemia were possibly in part caused by apoptosis. The inhibition of ischemic neuronal apoptosis was assumed to be a neuroprotective mechanism of mild hypothermia.