Inhibitory effect of gossypol on steroidogenic pathways in cultured bovine luteal cells.

Gossypol inhibits the reproductive system and steroidogenesis in both sexes. The present study investigated some possible sites subsequent to cAMP formation at which gossypol may inhibit progesterone biosynthesis. Bovine luteal cells were cultured with dibutyryl cAMP (dbcAMP), 25-OH cholesterol, or pregnenolone in the presence or absence of gossypol. Gossypol, at 17-34 microM, inhibited dbcAMP-induced progesterone secretion. Gossypol significantly inhibited the conversions of exogenous 25-OH cholesterol and pregnenolone to progesterone. However, the conversion of 25-OH cholesterol to pregnenolone was not significantly inhibited by gossypol at low doses (less than or equal to 34 microM). These results suggest that gossypol inhibits progesterone synthesis in bovine luteal cells by suppressing steroidogenic enzyme activity.