PLATELET DERIVED GROWTH-FACTOR INHIBITS 5-ALPHA-REDUCTASE AND DELTA-5-3-BETA-HYDROXYSTEROID DEHYDROGENASE-ACTIVITIES IN CULTURED IMMATURE LEYDIG-CELLS

Platelet derived growth factor inhibited both hCG- and 8-Br-cAMP-stimulated 5α-reductase activity in cultured immature Leydig cells in a dose-dependent manner, while not significantly inhibiting basal enzyme activity. Platelet derived growth factor also inhibited basal Δ5-3β-hydroxysteroid dehydrogenase activity and hCG-stimulated testosterone formation. Maximal inhibitions were achieved with 10 ng/ml of platelet derived growth factor. These studies suggest that platelet derived growth factor should be included among the variety of locally produced regulatory factors which modulate Leydig cell function. © 1990.