Morphometric and functional pulmonary changes of premature neonatal puppies after antenatal corticoid therapy

Abstract

Among prematurity complications, the most important disorder is structural immaturity and inadequate production of pulmonary surfactant. Betamethasone is the drug of choice to artificially improve pulmonary capacity, thus we aimed to verify the effect of prenatal maternal treatment on lung development of premature puppies. Pregnant bitches were allocated in Term Group (n = 7), Preterm-Treated Group (interrupted pregnancies with maternal administration of betamethasone; n = 7), Preterm-Control Group (untreated interrupted pregnancies; n = 7), Extremely-Preterm Group (interrupted pregnancies at 55d; n = 6). Puppies were subjected to chest radiographic at birth, morphometric description of pulmonary structures and immunohistochemical analysis of surfactant protein B, proliferating cell nuclear antigen and cytokeratin were performed. In Preterm-Treated Group it was possible to more clearly identify cardiac silhouette and lung parenchyma by X-Ray. Saccular formation was higher in Preterm Groups, while Term Group had higher subsaccular development. Lung septation was higher in Treated and Term Groups. Term Group had higher number of cells marked for SP-B, whereas higher proliferation was observed in Extreme-Preterm and Preterm-Control Groups. Preterm Treated and Term Groups had higher tissue differentiation. In conclusion, antenatal maternal corticotherapy in dogs acted by increasing lung morphology and development of areas of gas exchange, regulate metabolism of pulmonary fluids rather than stimulate surfactant production.