高血糖对大鼠局灶性脑缺血再灌注后神经细胞凋亡及caspase-9、caspase-3表达的影响

目的探讨高血糖对大鼠局灶性脑缺血再灌注后神经细胞凋亡及半胱氨酸天冬氨酸蛋白酶-9(caspase-9)、caspase-3表达的影响,进一步探讨其加重脑缺血损伤的作用机制。方法将30只雄性Sprague-Dawley(SD)大鼠随机分为3组:高血糖组、正常血糖组和假手术组。按体质量4g/kg给予大鼠尾静脉注射25%(质量浓度)的葡萄糖,造成大鼠高血糖状态;继而制作大脑中动脉阻塞脑缺血再灌注模型。于缺血2h再灌注24h进行神经功能评分,采用脱氧核糖核苷酸末端转移酶介导的dUTP缺口末端标记法(terminal-deoxy-nucleotidyl transferase mediated dUTP nick end labeling,TUNEL)检测大鼠脑组织细胞凋亡数,采用免疫组化染色检测大鼠脑组织caspase-9和caspase-3表达。结果 (1)高血糖组神经功能评分为(4.20±0.63)分,正常血糖组为(3.50±0.70)分,假手术组为0分。高血糖组及正常血糖组的神经功能评分较假手术组均显著增加(P<0.05),且高血糖组神经功能评分较正常血糖组增加(P<0.05)。(2)高血糖组凋亡细胞数为(16.30±3.30)个,正常血糖组为(14.60±3.27)个,假手术组为(0.50±0.53)个。高血糖组及正常血糖组的凋亡细胞数较假手术组增多(P<0.05),且高血糖组细胞凋亡数较正常血糖组增多(P<0.05)。(3)高血糖组caspase-9和caspase-3灰度值分别为114.30±3.83、111.50±3.17,正常血糖组分别为117.20±4.34、117.40±3.24,假手术组分别为146.20±1.98、146.80±0.74。高血糖组及正常血糖组的caspase-9和caspase-3表达水平较假手术组均增强(P<0.05),且高血糖组caspase-9和caspase-3表达水平较正常血糖组增强(P<0.05)。结论高血糖可增加缺血再灌注后脑神经细胞凋亡;caspase-9、caspase-3的激活及表达增强可能是高血糖加重脑缺血再灌注损伤的机制之一。

The effects of hyperglycemia on cell apoptosis and expressions of caspase-9,caspase-3 in rats with focal cerebral ischemia-reperfusion injury

Objective To study the effects of hyperglycemia on cell apoptosis and expressions of caspase-9 and caspase-3 in rats with focal cerebral ischemia-reperfusion injury and further to discuss the mechanism of hyperglycemia-induced cerebral ischemia injury.Methods Thirty adult male Sprague-Dawley(SD) rats were divided randomly into 3 groups: the hyperglycemic group,the normal glycemic group and the sham-operated group.Hyperglycemia was induced by tail vein injection of 25% glucose(4 g/kg),and focal cerebral ischemia injury was made by occluding the middle cerebral artery.Neurological deficits were estimated after 2 h ischemia and 24 h reperfusion.The apoptotic neurons were stained with the terminal-deoxynucleotidyl transferase mediated dUTP nick end labeling(TUNEL).The expressions of caspase-9 and caspase-3 were evulated with immunohistochemistry.Results(1)The scores of neurological deficit: The neurological deficit score was 4.20±0.63 in the hyperglycemic group,3.50±0.70 in the normal glycemic group,and 0 in the sham-operated group.The neurological deficit score was higher significantly in the hyperglycemic group,as well as in the normal glycemic group,in comparison with the sham-operated group(both P<0.05).Compared with the normal glycemic group,the neurological deficit score in the hyperglycemic group was higher(P<0.05).(2)The number of apoptotic neurons: The number of apoptotic neurons in the hyperglycemic group、the normal glycemic group and sham-operated group was respectively(16.30±3.30),(14.60±3.27) and(0.50±0.53).The number of apoptotic neurons in the hyperglycemic group and the normal glycemic group were higher than that in the sham-operated group significantly(P<0.05).Compared with the normal glycemic group,the number of apoptotic neurons in the hyperglycemic group was higher significantly(P<0.05).(3)Caspase-9 gray value detected by immunohistochemical staining: Caspase-9 gray value in the hyperglycemic group,the normal glycemic group and the sham-operated group were respectively(114.30±3.83),(117.20±4.34) and(146.20±1.98).Compared with the normal glycemic group,caspase-9 gray value in the hyperglycemic group was higher siginificantly(P<0.05).(4)Caspase-3 gray value detected by immunohistochemical staining: Caspase-3 gray value of the hyperglycemic group、the normal glycemic group and the sham-operated group were respectively(111.50±3.17),(117.40±3.24) and(146.80±0.74).Compared with the normal glycemic group,caspase-3 gray value in the hyperglycemic group was higher siginificantly(P<0.05).Caspase-9 and caspase-3 gray value in the hyperglycemic group and the normal glycemic group were higher than the sham-operated group significantly(P<0.05).Conclusions The increased expression of caspases-9 and caspases-3 may be one of the mechanisms in ischemia reperfusion injury aggravated by hyperglycemia.