Abstract
The physiological development and homeostasis of the lung alveolus is determined by the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) by the interstitial lipofibroblast. We have recently shown (Dasgupta C et al., Am J Physiol Lung Cell Mol Physiol 296: L1031-L1041, 2009.) that PPAR-γ agonists administered postnatally accelerate lung maturation and prevent hyperoxia-induced lung injury. However, whether the same occurs antenatally is not known. The objective of this study was to test the hypothesis that the potent PPAR-γ agonist rosiglitazone (RGZ), administered antenatally, enhances fetal lung maturation and protects against hyperoxia-induced neonatal lung injury. Sprague-Dawley rat dams were administered either diluent or RGZ (3 mg/kg), at late gestation, to determine its effect on lung maturation and on hyperoxia (95% O(2) exposure for 24 h)-induced neonatal lung injury. The lungs were examined for the expression of specific markers of alveolar development (surfactant proteins A and B, cholinephosphate cytidylyltransferase-α, leptin receptor, triglyceride uptake, and [(3)H]choline incorporation into saturated phosphatidylcholine) and injury/repair, in particular, the markers of transforming growth factor-β signaling (activin receptor-like kinase-5, SMAD3, lymphoid enhancer factor-1, fibronectin, and calponin). Overall, antenatal RGZ accelerated lung maturation and blocked the inhibition of alveolar sacculation and septal wall thinning by hyperoxia. RGZ specifically stimulated the development of the alveolar epithelial type II cell, the lipofibroblast, and the vasculature. The increased expression of the transforming growth factor-β intermediates, such as SMAD3 and lymphoid enhancer factor-1, implicated in hyperoxic lung injury, was also blocked by antenatal RGZ treatment. In conclusion, PPAR-γ agonists can enhance fetal lung maturation and can effectively prevent hyperoxia-induced neonatal lung injury.