Progestin augmentation of gonadotropin-stimulated progesterone production by cultured rat granulosa cells.

Ovarian progesterone production is stimulated by FSH and LH. Concomitant treatment with a synthetic progestin, R5020, (10(-6)M) increases the FSH-stimulated production of progesterone and 20 alpha-hydroxypregn-4-en-3-one (20 alpha-OH-P) in cultured rat granulosa cells. Likewise, R5020 augments the LH-stimulated progestin production in FSH-primed cells. Furthermore, the FSH stimulation of pregnenolone biosynthesis is enhanced by 10(-6) M of progesterone or R5020. These in vitro findings suggest that progestins may exert an autoregulatory positive feedback action to enhance gonadotropin-stimulated production of progesterone and 20 alpha-OH-P.