高压氧治疗对新生大鼠缺氧缺血性脑损伤模型

Effect of hyperbaric oxygenation therapy on the expression of Bcl-2, Bax and cytochrome C in nerve cells of neonatal rats with hypoxic-ischemic brain damage

摘要:

目的：探讨新生大鼠缺氧缺血性脑损伤(HIBD)模型脑组织神经细胞凋亡抑制蛋白Bcl2、促凋亡蛋白Bax的表达和胞浆线粒体细胞色素C(CytC)水平的关系及高压氧(HBO)对其的影响。方法：新生7日龄健康SD大鼠随机分为4组:空白对照组(n=34),假手术组(n=33,分离左颈总动脉后不结扎直接缝合皮肤),HIBD组(n=30,分离并结扎左颈总动脉联合8%低氧暴露2h),HBO组[n=33,HIBD后行HBO治疗(2个绝对大气压,1h/d,连续7d)]。免疫组织化学法检测脑组织神经细胞Bcl2和Bax的表达,Westernblot检测神经细胞胞浆线粒体CytC的水平。结果：HBO组Bcl2阳性细胞较HIBD组明显增多,阳性表达率分别为64%和47%(P<0.05),但较空白对照组(82%)和假手术组(79%)低,(P均<0.05);HBO组Bax免疫阳性细胞表达率(67%)与HIBD组(77%)比较差异无显著性(P>0.05),但明显高于空白对照组(15%)和假手术组(36%),(P<0.01和P<0.05)。空白对照组和假手术组神经细胞胞浆仅有弱阳性的CytC表达,HIBD组胞浆CytC的表达最强,HBO组的表达较HIBD组减轻。结论：HBO治疗可能通过诱导脑组织神经细胞Bcl2蛋白的表达,减轻线粒体CytC的释放,从而减轻缺氧缺血性脑损伤后神经细胞的凋亡。

Abstract:

OBJECTIVE: This study examined the expression of Bcl-2, Bax and cytochrome C (Cyt C) in nerve cells and the effect of hyperbaric oxygenation (HBO) therapy on the expression levels in a neonatal rat model of hypoxic-ischemic brain damage (HIBD). METHODS: Seven- day-old SD rats weighing 12-14 g were randomly assigned into four groups:Normal group (n=34), Sham -operated group (n=33), of which the left common carotid artery of the rats was isolated but not ligated, HIBD group (n=30) in which the rats were subjected to left common carotid artery ligation followed by 2 hrs of hypoxia (8% O_2) and HBO treated group (n=33). HBO treatment was administered by placing the pups in a chamber after HIBD (2 atmosphere absolute for 1 hr per day for 7 days) in the HBO treated group. The expression of Bcl-2 and Bax in nerve cells of the brain was determined by immunohistochemistry and Cyt C expression was determined by Werstern blot analysis. RESULTS: The expression rate of Bcl-2 protein in the HBO treated group was obviously higher than that in the HIBD group(64% vs 47%, P < 0.05)), although it was lower than in the Normal group (82%) and the Sham-operated group (79%)(both P < 0.05). The expression rate of Bax protein in the HIBD group (77%) was significantly higher than that in the Normal group (15%, P < 0.01) and the Sham-operated group (36%, P < 0.05). HBO treatment did not result in a decreased expression of Bax protein. Cyt C was weakly expressed in nerve cells of the Normal and the Sham-operated groups, but was strongly expressed in the HIBD group. HBO treatment significantly decreased the Cyt C expression. CONCLUSIONS: HBO treatment can induce the expression of Bcl-2 protein and decrease the release of Cyt C from mitochondria, thereby protects the nerve cells from apoptosis after HIBD.