Inhibitory effect of nomegestrol acetate on steroidogenesis of cultured granulosa cells from rat ovary in vitro

To study the effect of nomegestrol acetate, a new synthetic progesterone on granulosa cells' viability and steroidogenesis function. Granulosa cells were cultured in McCoy's 5A medium. Trypan blue stain was used to measure viable cells. FSH and testosterone were added to stimulate the steroid secretion. Specific RIA assay was used to evaluate the estrogen and progesterone secretion respectively. IC50 of nomegestrol acetate to damage cells is 6.85 mg/L (95 % confidence limits 5.36-8.75 mg/L). Nomegestrol acetate 0.45, 0.9, and 1.8 mg/L greatly inhibited the estrogen secretion from granulosa cells by 7.6 %, 12.5 %, 28.3 % in the presence of testosterone 0.5 micromol/L and FSH 10 U/L without affecting the number of viable cells. The secretion of progesteron were markedly decreased by 44.5 %, 53.3 %, and 62.0 % concurrently. Nomegestrol acetate directly inhibited the steroidogenesis of granulosa cells.