Dynamic Changes of Bax/Bcl-2 Expression in Lung Tissue and Fibroblasts of Neonatal Rats after Inhaling High Concentration Oxygen

Objective To provide more information of Bax and Bcl-2 expression in lung tissue and lung fibroblasts in newborn rats with chronic lung disease(CLD) caused by hyperoxia.Methods Full-term newborn rats were continuously exposed to oxygen(900 mL·L-1) or room air within 12 hours after birth.Lung specimens were obtained and primary culture of lung fibroblasts were made respectively on postnatal days 3,7 and 14.Bcl-2 and Bax were quantitated by immunohistochemistry both in lung tissue and fibroblasts.Results In lung tissue,Bcl-2 was significantly elevated in the hyperoxia-exposed lungs at 7 and 14 days(P0.001),but not at 3 days(P0.05).The expression of Bax and the ratios of Bax/Bcl-2 were significantly higher in the hyperoxia-exposed lungs from 3 days of age and reached a peak at 14 days(P0.01).In fibroblasts,Bcl-2 was significantly elevated in the hyperoxia groups at 14 days(P0.001),but not at 3 and 7 days(P0.05).The expression of Bax and the ratios of Bax/Bcl-2 were significantly higher in the hyperoxia groups at 3,7 and 14 days(P0.01).Conclusion Prolonged hyperoxia results in the shifting balance of Bax and Bcl-2 may promote apoptosis of lung fibroblasts and be related to the evolution of the CLD.