纯氧与空气复苏对窒息新生大鼠心肌细胞凋亡及Bcl-2、Bax蛋白表达的影响

Effects of pure oxygen and room-air resuscitation on myocardial cell apoptosis and expressions of Bcl-2 and Bax protein in neonatal rats after asphyxia

目的:在建立新生大鼠窒息的动物模型基础上,比较纯氧与空气复苏对窒息新生大鼠心肌细胞凋亡及Bcl-2、Bax蛋白表达的影响。方法:采用SD新生大鼠建立窒息模型2.5h,并分组进行纯氧与空气复苏。实验分为正常对照组、纯氧复苏组(PO组)和空气复苏组(RA组),均在复苏后24h和72h取心肌组织,制成石蜡切片,HE染色光镜观察心肌组织病理变化,TUNEL法测定心肌细胞凋亡指数,免疫组织化学S-P法检测心肌组织Bcl-2、Bax蛋白的表达情况。结果:HE染色光镜观察,与正常对照组相比,PO组可见大部分心肌纤维肿胀,有少许断裂,心肌间质及小静脉明显淤血,RA组心肌纤维则表现明显的片状或灶性坏死。RA组心肌细胞凋亡指数明显高于PO组,且以24h升高最显著。PO组凋亡抑制基因Bcl-2表达高于RA组,RA组促凋亡基因Bax明显高于PO组。结论:空气复苏较纯氧复苏后心肌细胞凋亡更严重,且以复苏后24h最明显,空气复苏促进Bax基因的表达上调,纯氧复苏可使凋亡抑制基因Bcl-2表达上调,提示高浓度氧对窒息复苏后心肌有一定的保护作用。

Objective To compare the effect of pure oxygen resuscitation with that of room-air resuscitation on myocardial cell apoptosis and expressions of Bcl-2 and Bax protein using the neonatal rat model of asphyxia. Methods The neonatal SD rat model of asphyxia was established for 2.5 h and the rats were then divided into normal control group, group with pure oxygen resuscitation （PO group）, and group with room-air resuscitation （RA group）. Pathological changes of the myocardial tissues were microscopically observed using HE staining 24 h and 72 h after resuscitation. Apoptotic index of the myocardial cell was detected by TUNEL assay, and expressions of Bcl-2 and Bax protein in the myocardial tissues were detected by immunohistochemistry （S-P method）. Results As compared with those in the normal control group, in PO group most myocardial fibers were swelling and some were ruptured and myocardial interstitial and venules were apparently congested,in RA group, however, myocardial fibers showed obvious flake-like or focal necrosis. There was no significant difference in the present of pathological changes between the two groups. The apoptotic index was markedly greater in RA group than in PO group, with the highest level at 24 h. The expression of Bcl-2, an anti-apoptotic gene, was stronger in PO group than in RA group whereas the expression of Bax, a pro-apoptotie gene, was significantly weaker. Conclusions Myocardial cell apoptosis is more serious using room-air resuscitation than pure oxygen resuscitation, especially 24 hours after resuscitation. Room-alr resuscitation promotes the upregulation of Bax expression and pure oxygen enhances the upregulation of Bcl-2 expression, suggesting that a higher concentration of oxygen plays a role in protection of the myocardial cell after asphyxia.