RESUMO
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.
Assuntos
Androstenodiona/biossíntese , Gossipol/farmacologia , Hormônio Luteinizante/farmacologia , Progesterona/biossíntese , Células Tecais/metabolismo , Animais , Bovinos , Células Cultivadas , Enzima de Clivagem da Cadeia Lateral do Colesterol/genética , Enzima de Clivagem da Cadeia Lateral do Colesterol/metabolismo , Óleo de Sementes de Algodão , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Feminino , Expressão Gênica/efeitos dos fármacos , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Progesterona Redutase/genética , Progesterona Redutase/metabolismo , Esteroide 17-alfa-Hidroxilase/genética , Esteroide 17-alfa-Hidroxilase/metabolismo , Esteroide Isomerases/genética , Esteroide Isomerases/metabolismo , Células Tecais/enzimologiaRESUMO
Glucocorticoid action in target organs is regulated by relative activities of 11ß-HSD type 1 (HSD11B1) that mainly converts cortisone to active cortisol and type 2 (HSD11B2) that inactivates cortisol to cortisone. HSD11Bs have been shown to be expressed in the ovary of various species. However, little is known about the expression and activity of HSD11Bs in the bovine cumulus-oocyte complex (COC). In the present study, we investigated the expression and activities of HSD11Bs in in vitro-matured (IVM) bovine COCs. Bovine COCs were matured in M199 supplemented with or without FSH and FCS. The expression of HSD11B1 and HSD11B2 was measured by using quantitative RT-PCR in denuded oocytes (DO) and cumulus cells (CC). Reductive and oxidative activities of HSD11Bs were determined by radiometric conversion assay using labeled cortisol, cortisone or dexamethasone in intact COCs, DO or CC in the presence or absence of 11-keto-progesterone (11kP), a selective inhibitor of HSD11B2. The presence of HSD11Bs in the oocyte was examined by immunofluorescence microscopy. Oocytes exclusively expressed HSD11B2 and its expression and activity were largely unchanged during IVM. CC, on the other hand, exclusively expressed HSD11B1 and its expression and activity were upregulated as IVM progressed. As a result, the net glucocorticoid metabolism shifted from inactivation to activation towards the end of IVM. These results indicate that the bovine COC is capable of modulating local glucocorticoid concentration and, by doing so, may create an environment that is favorable to ovulating oocyte for maturation, fertilization and subsequent development.
