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《Chinese Journal of Perinatal Medicine》 2006-05
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Effect of 60% oxygen exposure on expression of Bax and Bcl-X_L in lungs of newborn rats

WANG An-ru, WANG Wei, LIU Xin, et al. Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China  
Objective To investigate the effect of Bax and Bcl-X_L expression in newborn rat with moderate hyperoxic exposure. Methods Hyperoxic lung injury model was established by exposure to 60% O_2 in the neonatal period of SD rats. Rats exposed to air were used as control groups, with 8 animals in each group on repeated experiments. The pathology of pulmonary tissues was detected by HE stain. Mean alveolar area and alveolar number per μm~2 were applied to estimate the pathological effects of prolonged hyperoxia in neonatal rats. The expression of Bax and Bcl-X_L proteins in lung were detected by immunohistochemistry and the expressions of Bax and Bcl-X_L mRNA by RT-PCR. Results In hyperoxia groups, alveolar dysplasia appeared 4 days after hyperoxia, mean alveolar area increased and alveolar number per μm~2 decreased from the 4th day. Bax and Bcl-X_L protein were mainly expressed on bronchiolar epithelial cells and vascular endothelial cells. Compared with control group, the expression of Bax increased from the 1st day after hyperoxia, Bax mRNA decreased from the 11th day (q=8.4802, P0.05) and the level of Bax protein decreased until the 14th day (q=6.8364, P0.05). The expression of Bcl-X_L mRNA augmented from the 1st to 14th day, while the expression of its protein diminished on the 1st day (q=10.4299, P0.05) and then raised up. With the prolonged duration of hyperoxia, the levels of Bax mRNA, its protein and Bcl-X_L mRNA degraded, while the level of Bcl-X_L protein upgraded. In the air groups, the level of Bax mRNA increased on the 11th day after exposure and the level of its protein increased on the 14th day after exposure. The levels of Bcl-X_L mRNA and protein were the highest among the air groups on the 1st day. Conclusions Apoptosis is timely related with oxygen exposure manifested by significant apoptosis early after hypoxic exposure and reduced apoptosis after longer duration.
【Fund】: 国家杰出青年科学基金资助项目(30125019);; 国家自然科学基金面上项目(30271379)
【CateGory Index】: R722.1
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