Abstract
Antenatal steroids (ANS) accelerate fetal lung maturation and reduce the incidence of respiratory distress syndrome. However, sex specificity, i.e., being less effective in males, and potential long-term neurodevelopmental sequelae, particularly with repeated courses, remain significant limitations. The differential sex response to ANS is likely mediated via the inhibitory effect of fetal androgens on steroid's stimulatory effect on alveolar epithelial-mesenchymal interactions. Since peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists accelerate lung maturation by stimulating alveolar epithelial-mesenchymal interactions, independent of fetal sex, we hypothesized that the effect of PPAR-γ agonist pioglitazone (PGZ) would be sex-independent. Pregnant Sprague-Dawley rat dams were intraperitoneally administered dexamethasone (DEX) or PGZ on embryonic day (e) 18 and e19. At e20, pups were delivered by cesarean section, and fetal lungs and brains were examined for markers of lung maturation and apoptosis, respectively. Mixed epithelial-fibroblast cell cultures were examined to gain mechanistic insights. Antenatal PGZ increased alveolar epithelial and mesenchymal maturation markers equally in males and females; in contrast, antenatal DEX had sex-specific effects. Additionally, unlike DEX, antenatal PGZ did not increase hippocampal apoptosis. We conclude that PPAR-γ agonist administration is an effective, and probably even a superior, alternative to ANS for accelerating fetal lung maturity equally in both males and females.