Abstract: Objective To explore the variation of RB (retinoblastoma, RB ) phosphorylation in lung fibroblasts of neonatal rats treated with hyperoxia.. Methods In 12 hours after birth, full-term newborn rats were continuously exposed to oxygen (0.85) or room air. Pups were randomly selected to be sacrificed on postnatal 3d, 7d, 14d and 21d, lungs were immediately resected under sterile condition and primary cell culture were done. the protein expressions of RB and phosphorylated RB(p-RB, ser-795) were detected by immunohistochemistry. Results Exposure neonatal rats in hyperoxia for 3 days did not change the expression of p-RB in lung fibroblast.(p>0.05). However, the expression of p-RB in hyperoxia groups was significant upregulated on 7day, 14day and 21day compared with that in air-exposed groups(p<0.05 on 7 day, p<0.01 on 14day and 21day). No notable difference was observed in the expression of RB between hyperoxia groups and air-exposed groups. Conclusion Exposure of neonatal rats in hyperoxia can down-regulate expression of P16 gene, change the phosphorylation of RB protein, ultimately lead the pulmonary interstitial fibrosis.

Key words: hyperoxia, chronic lung disease, RB phosphorylation, lung fibrolast.