Dynamic Effects of Prolonged Inhaling High Concentration of Oxygen on Collagen Type Iand IV Massenger Ribonucleic Acid Expression in the Lung Tissue of Neonatal Rats

Objective To explore the dynamic changes of collagen type Ⅰand Ⅳ messenger ribonucleic acid(mRNA)expression in the lung tissue of neonatal rats after inhaling high concentration of oxygen and the role of collagen type Ⅰand Ⅳ mRNA in chronic lung disease(CLD)induced by hyperoxia.Methods Full-term newborn rats were grouped according to inhale the concentration of oxygen into hypero-xia group and air control group after birth within 12 hours.Lung histological section at day 1,3,7,14 and 21 in 2 groups were prepared for hematoxylin-eosin staining and the detection of mRNA level of collagen type Ⅰand Ⅳ by in situ hybridization.The results were analyzed with SPSS 11.0 software.Results Compared with air control group,inflammation response was seen in early stage,the arrest of lung development was evident after 7 d of oxygen exposure,at last interstitial fibrosis.It was shown that the positive expression of collagen typeⅠ was mainly in the alveolar epithelial cells and endothelial cells by in situ hybridization.The expression of collagen typeⅠ mRNA was weakened compared to air group on 7 d(P0.05)and 14 d of oxygen exposure(P0.01).While for collagen type Ⅳ,the positive expression was mainly in the endothelial cells,whose mRNA expression showed no evident change between two groups on each time(Pa0.05).Conclusions Prolonged hyperoxia may cause the onset of arrested lung development and lung fibrosis,which are similar to the changes of chronic lung disease.The collagen type Ⅰand Ⅳ mRNA expressions are not parallel to their protein contents,suggesting the main modulation of these collagens may be not at transcriptional level.