Dihydrotestosterone stimulates branching morphogenesis, cell proliferation, and programmed cell death in mouse embryonic lung explants

Early gestation lung development is characterized by branching morphogenesi s of the airways and basic lung structure formation. Androgens delay late-g estation lung development if the androgen exposure begins in early gestatio n. We hypothesized that there would be effects of early gestation androgens on lung development. Embryonic mouse lungs (d 11.5) were cultured with dih ydrotestosterone (DHT), DHT plus flutamide, or with nothing as controls. Br anching morphogenesis was significantly increased after 24, 48, and 72 h of culture. This effect was blocked by simultaneous flutamide treatment. Feta l sex did not influence the DHT response. DHT increased cell proliferation as measured by [H-3]thymidine incorporation into DNA. Autoradiography showe d prominent [H-3]thymidine labeling of epithelia and mesenchyme in regions of new bud formation. DHT treatment significantly increased the thymidine-l abeling index of fibroblasts and airway epithelial cells. Programmed cell d eath, which is found in developing organs in association with cell prolifer ation during structure formation and tissue remodeling, was studied using t erminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling assay. In control lungs, programmed cell death occurred in the pe ripheral mesenchyme surrounding newly forming buds and underlying airway br anch points. DHT treatment increased programmed cell death in association w ith increased branching morphogenesis. Evaluation of near-adjacent sections (control and DHT-treated lungs) showed that apoptotic mesenchymal cells we re flanked by [H-3]thymidine-labeled fibroblasts and epithelial cells, sugg esting a coordination of these processes in the progression of branching mo rphogenesis. We conclude that androgen enhances the process of early lung m orphogenesis by increasing cell proliferation and programmed cell death and by promoting the structural progression of branching morphogenesis.