Effects of gossypol on in vitro bovine oocyte maturation and steroidogenesis in bovine granulosa cells

Abstract

Abstract Recently, we demonstrated an adverse effect of gossypol on steroidogenesis of bovine luteal, porcine granulosa and rat adrenocortical cells as well as on bovine, rat and hamster early embryonic development. The purpose of this study was to evaluate the effects of varying dosages of gossypol on bovine oocytes and granulosa cells from small and large follicles. Oocytes and bovine granulosa cells from small follicles were harvested from 3- to 8-mm follicles, and bovine granulosa cells from larger follicles (>15 mm) were used. Bovine oocytes were cultured in the presence of 10, 50 and 150 μg/ml gossypol for 26 to 28 h. Both bovine granulosa cells and bovine granulosa cells from larger follicles were treated with 0.1, 0.5, 2.5 and 12.5 μg/ml gossypol in the presence or absence of human chorionic gonadotropin (hCG) for 6 h. Cumulus expansion, meiotic progression of oocytes, progesterone production and intracellular cAMP formation in granulosa cells were measured. Gossypol significantly decreased cumulus expansion and inhibited nuclear maturation of oocytes. In bovine granulosa cells, gossypol inhibited cAMP formation only at 12.5 μg/ml. In bovine granulosa cells from larger follicles, hCG significantly increased both progesterone and cAMP levels. Treatment with gossypol significantly decreased hCG-induced cAMP formation in a dose-dependent manner. Basal cAMP level and progesterone secretion were significantly inhibited by only 12.5 μg/ml gossypol. However, inhibition of hCG-induced progesterone secretion was more dramatic. These results indicate that gossypol is capable of inhibiting cumulus expansion and nuclear maturation of bovine oocytes, and progesterone production and cAMP formation in bovine granulosa cells from larger follicles.