Differential Gene Expression of Antioxidant Enzymes in the Perinatal Rat Lung

It has been previously demonstrated that the developing rat lung markedly increases its catalase (CAT) and glutathione peroxidase (GP) activities during the final 10 to 15% of gestation. In the present studies, we tested whether four major antioxidant enzymes (AOE) in peri- natal rat lungs might share a similar pattern of develop- mental AOE gene expression via a pretranslational mech- anism. The left lungs of 18-d to term fetuses and early postnatal rat pups were used to measure the concentrations of AOE mRNA by solution hybridization and the right lungs of the same group of animals were assayed for AOE activities. Results revealed differential AOE gene expres- sion in developing rat lungs. Whereas the CAT and GP activities progressively increased prenatally, the superox- ide dismutase (SOD) activity either declined (copper-zinc SOD (Cu,ZnSOD)) or remained constant (manganese SOD (MnSOD)) in late gestation. Postnatally, Cu,ZnSOD and CAT activities progressively increased, whereas MnSOD remained constant and GP activity declined slightly. For Cu,ZnSOD, MnSOD, and CAT, the activity changes were generally consistent with the patterns of changes in their mRNA concentrations in both the prenatal and postnatal period, but for GP they were not. At the time of birth, however, the mRNA levels of Cu,ZnSOD and CAT de- creased -40%, whereas their enzyme activities increased. For MnSOD, only a slight rise in mRNA level was ob- served versus -100% increase in its activity at the time of birth. These findings suggest that the AOE are not coor- dinately regulated, and that developmental regulation of AOE gene expression in the perinatal rat lung is complex and likely exerted at different levels of regulation. (Pediatr