Expression changes of cytochrome oxidase genes in hyperoxia induced lung injury in premature newborn rat.

Objective To observe the expression of mitochondrial encoding cytochrome oxidase genes(COXI、COXII、COXIII)in lungs of premature newborn rats exposed to 85% hyperoxia and explore the role of COX in hyperoxia-induced lung injury.Methods The one-day-old premature SD rats were randomly divided into room air group and hyperoxia group.Hyperoxia group were continuously exposed to 85% oxygen and air group in room air.After 1,4,7,10,14 days of exposure,eight rats of each group were sacrified to assess lung histopathologic changes.Expression of COXI,COXII and COXIII mRNA were detected by reverse transcription polymerase chain reaction(RT-PCR).Results(1) lung pathological changes:On day 4 of exposure,hyperoxia group showed lung injury characterized by alveolitis and inhibition of lung development.(2) expression of mRNA:As compared with that of room air group,COXI mRNA expression of hyperoxia group first increased significantly on day 1 and day 4(P0.05 and P0.01 respectively),then decreased to the equivalent level on day 7(P0.05) and a lower level on day 10,but finally recovered the increasing tendency to a significantly higher level on day 14(P0.01).There were not significant differences of COXIIand COXIII mRNA expression levels between two groups at every time point.Conclusion Exposure of 85% hyperoxia has significant impact on the expression of cytochrome oxidase subunits in premature newborn rats,which is likely to contribute to the pathogenesis of hyperoxia-induced lung injury.