Gossypol inhibits LH‐induced steroidogenesis in bovine theca cells

Gossypol, a polyphenolic aldehyde found in cottonseed, has been shown to perturb steroidogenesis in granulosa and luteal cells of rats, pigs and cattle. However, little is known about the direct effect of gossypol on theca cell functions in any species. The present study was conducted to investigate the effect of gossypol on the steroidogenesis and the expression of genes involved in it in cultured bovine theca cells. Theca cells were isolated from healthy preovulatory follicles and were cultured in the presence of luteinizing hormone (LH) for up to 7 days. During the culture period, main steroid products of the theca cells shifted from androstenedione (A4) at day 1 to progesterone (P4) from day 2 onward. At days 1 and 7, theca cells were treated with gossypol (0‐25 μg/mL) for 24 h. Gossypol inhibited LH‐stimulated theca cell A4 and P4 production in a dose‐dependent manner at both occasions. The viability of theca cells was not affected by gossypol at any doses used. Gossypol down‐regulated expressions of steroidogenic enzymes CYP11A1, HSD3B1 and CYP17A1, but not that of LHR. These results indicate that gossypol inhibits thecal steroidogenesis through down‐regulating gene expressions of steroidogenic enzymes but without affecting cell viability in cattle.