亚低温对大鼠急性脑缺血再灌注损伤后脑组织半胱氨酸蛋白酶-12表达及神经元凋亡的影响

Influence of mild hypothermia on expression of caspase-12 and neuron apoptosis in brain tissue in rats with acute cerebral ischemia-reperfusion injury

目的观察亚低温对大鼠急性脑缺血再灌注损伤后脑组织半胱氨酸蛋白酶(caspase)-12表达及神经元凋亡的影响。方法 56只大鼠随机分为正常组、假手术组、缺血组和亚低温组;后两组再分为再灌注3 h、6 h、12 h、24 h、72 h及7 d 6个亚组。应用线栓法制作大鼠大脑中动脉栓塞局灶性脑缺血(2 h)再灌注模型;亚低温组于缺血30 min实施病灶侧头部亚低温4 h。各组大鼠在相应时点处死前行神经功能缺损评分(NDS);脑组织切片行HE、免疫组化及原位末端标记法(TUNEL)染色观察病理改变、caspase-12表达及神经元凋亡。结果正常组及假手术组脑组织均未见明显病理改变及caspase-12和TUNEL阳性细胞。缺血组可见明显的脑梗死灶,大量神经元坏死及消失;亚低温组梗死灶较小,可见神经元固缩。与缺血组比较,亚低温组各时间点亚组NDS明显降低,脑组织caspase-12及TUNEL阳性细胞数明显减少(均P<0.05)。结论急性脑缺血再灌注损伤后亚低温治疗可抑制脑组织caspase-12表达,减少神经元凋亡及神经功能的损害。

Objective To observe the influence of mild hypothermia on expression of caspase-12 and neuron apoptosis in brain tissue in rats with acute cerebral ischemia reperfusion injury.Methods Fifty-six rats were randomly divided into normal group,sham-operation group,ischemia group and mild hypothermia group.The last two groups were again randomly divided into reperfusion 3 h,6 h,12 h,24 h,72 h and 7 d total 6 subgroups.The rat focal cerebral ischemia（2 h）reperfusion models were established by modified thread embolism.The mild hypothermia on lesions side of head in mild hypothermia group was performed at 30 min after ischemia for 4 h.In the corresponding time point before the rats put to death,the neural functional defect score（NDS） was evaluated.The cerebral tissue slices were HE staining,immunohistochemical staining and in situ end labeling method（TUNEL）to observed the pathology change,and caspase-12,TUNEL positive cells.Results In the normal group and sham-operation group,the pathological change and caspase-12,TUNEL positive cells were not found out in the brain tissue.The cerebral infarction lesions in ischemic group was obviously,and a large number of neurons was necrosis and disappear.The cerebral infarction lesions in the mild hypothermia group was smaller and neurons pyknosis could be observed.Compared with the ischemic group,NDS in the mild hypothermia group in each time point subgroup were significantly decreased,the quantity of caspase-12,TUNEL positive cells in cerebral tissue were remarkably reduced（allP0.05）.Conclusion Mild hypothermia can inhibited the expression of caspase-12 in cerebral tissue,reducing neuron apoptosis and nerve function damage after cerebral ischemia reperfusion injury.