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

AIM: To study the effect of nomegestrol acetate, a new synthetic progestero ne on granulosa cells' viability and steroidogenesis function. METHODS: Gra nulosa 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. RESULTS:IC50 of nomegestrol acetate t o damage cells is 6.85 mg/L, (95 % confidence limits 5.36-8.75 mg/L). Nomeg estrol acetate 0.45, 0.9, and 1.8 mg/L, greatly inhibited the estrogen secr etion from granulosa cells by 7.6 %, 12.5 %, 28.3 % in the presence of test osterone 0.5 mu mol/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. CONCLUSION: Nomegestrol acetate directly inhi bited the steroidogenesis of granulosa cells.