Postnatal selenium repletion protects lungs of neonatal rats from hyperoxia

We reported previously that Se-adequate neonatal rat pups born to Se- adequate dams were resistant to lung damage by hyperoxia. To assess whether early postnatal Se repletion could also protect developing pups reared under hyperoxia, female Sprague-Dawley rats (n = 20) were bred and fed a Se- deficient (0.04 μg/g) diet during pregnancy. On d 1 postpartum, dams were divided into two groups and fed either a Se-deficient diet or a Se-repleted (0.5 μg/g) diet. On d 4 postpartum, litters in each group were randomly assigned to either air or high oxygen (>95% O₂) environments. Histologic evaluation of lungs from d-8 pups indicated that Se repletion significantly reduced the incidence of lung lesions caused by hyperoxia. Selenium-repleted pups also had significantly greater lung volumes and internal surface areas. The 7-d period of Se repletion resulted in significantly elevated maternal milk Se concentrations compared with a Se-deficient group, which was reflected in the pups by elevated plasma and hepatic Se concentrations and Se-dependent glutathione peroxidase (SeGPx) activities. Pulmonary glutathione concentration and SeGPx activity in pups were affected by oxygen exposure only, not by Se nutrition. Therefore, early postnatal Se repletion can protect the developing lung from oxygen-induced injury, a protection that is not entirely due to the effects of Se on pulmonary SeGPx activity and glutathione concentration.