Assistant Professor University of Oklahoma Health Sciences Center Oklahoma City, Oklahoma, United States
Background: Selenium (Se) modulates endogenous antioxidant responses. Extremely and very low birthweight infants are up to 17-times more likely to be Se deficient than term infants. Selenoenzymes modulate the activity of the glutathione and thioredoxin antioxidant systems. The impacts of Se neonatal lung antioxidant capacity are unknown. Objective: The presents studies tested the hypothesis that maternal Se supplementation (prenatally vs postnatally) would restore the diminished antioxidant responses caused by Se deficiency. Design/Methods: Male and female C3H/HeN mice were fed Se-sufficient (SeS; 0.4 ppm Na2SeO3) or Se-deficient (SeD; < 0.01 ppm Na2SeO3) diets from weaning and subsequently bred to create SeS and SeD litters. After birth, SeS and SeD pups either remained with their corresponding dams or were nursed by SeS and SeD dams to create 4 maternal/pup groups: SeS/SeS (control), SeS/SeD, SeD/SeD, or SeD/SeS. Pups were exposed to room air (21% O2) or hyperoxia (85% O2) from birth through 14 d. Upon euthanasia, lung tissues were harvested, and homogenates analyzed for glutathione peroxidase (Gpx)-1, -2, -3, -4; thioredoxin reductase 1 (Txnrd1), and Selenoprotein P (Selenop). Data (mean ± SD, n=6-11) were analyzed by 2-way ANOVA followed by Tukey’s post-hoc (p < 0.0001). Results: Lung GPX activity was not measurable in lung tissues from SeD/SeD pups. SeS /SeD pup tissues had measurable but low GPX activities. SeD/SeS pups had near 50% GPX activity compared to controls in both room air and 85% O2. Similarly, GPX-1, -2, -3, and -4 protein levels were minimally detectable in SeS/SeD and SeD/SeD pup tissues, but levels were equal to or greater than control in SeD/SeS pups. Txnrd protein levels were not different in RA but were 40% higher in SeD/SeS pups exposed to 85% O2, compared to control. Sepp levels were lower in SeD/SeD pups in room air but SeD/SeD, SeS/SeD, and SeD/SeS pup tissues exposed to 85% O2 had lower levels of Sepp than controls.
Conclusion(s): Our data indicate that postnatal Se supplementation is more efficacious at restoring normal antioxidant expression than prenatal Se supplementation in the context of Se deficiency. This observation could have important clinical implication in providing appropriate levels of Se supplementation to preterm infants after birth to optimize antioxidant capabilities.
