Antenatal dexamethasone improves atrial natriuretic peptide receptors in hypoplastic: lung in nitrofen-induced diaphragmatic hernia in rats

Atrial natriuretic peptide (ANP) plays a major role in electrolyte and volu me homeostasis through potent biological effects including vasorelaxation, bronchorelaxation, lung permeability, and clearance. There are two distinct biochemical and functional classes of ANP receptors, guanylate cyclase rec eptor (GC-R) and clearance receptors (clearance-R). Two subtypes of GCR hav e been described, GCA-R and GCB-R. Antenatal glucocorticoid therapy (AGT) h as been demonstrated to improve pulmonary immaturity and abnormal structure of pulmonary arteries in animal models of congenital diaphragmatic hernia (CDH). The aim of this study was to investigate the effect of antenatal glu cocorticoid administration on the ANP system in nitrofen-induced CDH hypopl astic lung in rats. A CDH model was induced in pregnant rats following admi nistration of nitrofen on day 9.5 of gestation. Dexamethasone (Dex) was giv en intraperitoneally on days 18.5 and 19.5; cesarean section was performed on day 21. Reverse transcription polymerase chain reaction was performed to evaluate the relative amounts of GCA-R, GCB-R and clearance-R mRNA express ion. The mRNA expression of GCA-R, GCB-R, and clearance-R was significantly increased in CDH compared to control lung. ANP receptor mRNA expression wa s significantly decreased in CDH lung with compared to without Dex treatmen t. Our finding of increased ANP receptor mRNA expression in CDH lung sugges ts that the hypoplastic lung has high sensitivity for ANP. Decreased mRNA e xpression of ANP receptors in CDH lung after Dex treatment suggests that AG T may improve pulmonary physiological function of ANP in hypoplastic CDH lu ng.