二氮嗪对大鼠脑缺血再灌注细胞凋亡的影响

Effects of diazoxide on neuronal apoptosis after acute cerebral ischemia-reperfusion in rats

目的研究二氮嗪开放线粒体ATP敏感性钾通道对大鼠脑缺血再灌注细胞凋亡的影响。方法采用线栓法建立大鼠局灶性脑缺血再灌注损伤模型,将20只大鼠随机分成4组,假手术组、缺血组、缺血+二氮嗪治疗组和缺血+二氮嚷+MitoK_(ATP)通道特异性抑制剂5-HD组。观察各组凋亡细胞数和凋亡相关蛋白Bcl-2、Bax的变化。结果与缺血组比较,二氮嗪使凋亡细胞数明显减少(83.2±9.04 vs 123.96±13.45),Bcl-2表达增高(0.17±0.01 vs 0.13±0.01),Bax表达下降(0.15±0.02 vs 0.20±0.03),差异具有显著性(P<0.05)。5-HD能取消这些作用(P<0.05)。结论局灶性脑缺血再灌注损伤时,二氮嗪能通过上调半暗带区Bcl-2蛋白表达,下调Bax蛋白表达,减少神经元凋亡,对脑缺血损伤起保护作用。

Objective To investigate the effects of diazoxide on neuronal apoptosis after middle cerebral artery occlusion （MCAO） in male Sprague-Dawley rats. Methods The rat focal cerebral ischemia and reperfusion model was performed by 2h thread embolism of middle cerebral artery and 22h of reperfusion（I/R）. Diazoxide,a selective opener of MitoKATp,was infused into the right lateral ventricle 30min before MCAO. 20 rats were assigned to 4 groups randomly,which received 1 of the following pretreatments before I/R：sham operation,I/R,I/R after giving diazoxide and I/R after giving diazoxide and 5-HD,a selective blocker of MitoKnTp. DNA fragmentation was measured in paraffin sections with the use of a terminal deoxynucleotidyl transferase （TdT） mediated dUTPbiotin nick end-labeling （TUNEL） method. Bcl-2 and Bax were measured by immunohistochemical method. Results When opened MitoKATp channels by using diazoxide,apoptotic cells exhibiting DNA fragmentation decreased （83.2±9.04 vs 123.96±13.45） ,the expression of Bcl-2 protein increased （0.17±0. 01 vs 0.13±0. 01） while the expression of Bax decreased（0. 15±0.02 vs 0.20±0.03） （P〈0.05）. The effects of diazoxide were completely abolished by 5-HD（P〈0.05）. Conclusion Diazoxide plays a benefit role in rat cerebral ischemia and reperfusion injury through inhibiting neuron apoptosis ,up-regulating Bcl-2 expression while down-regulating Bax expression.