Effect of adiponectin on estradiol and progesterone secretion from human luteinized granulosa cells in vitro.

Ιnformation on the role of adiponectin in human ovarian steroidogenesis is limited. The present study aimed to investigate the effect of different doses of adiponectin on the secretion of estradiol and progesterone by human luteinized granulosa cells in culture. Granulosa cells, obtained from women undergoing in vitro fertilization (IVF) treatment, were pre-incubated for 24 h and then cultured for 48 h. Adiponectin was used in 3 doses, i.e., 5, 10, and 100 µg/ml alone and in combinations with FSH (10 and 100 ng/ml). Estradiol and progesterone were measured by radioimmunoassays in culture supernatants at 24 h and 48 h. Adiponectin after 48 h of culture stimulated the secretion of estradiol and, to a lesser extent, progesterone in a dose-dependent manner. FSH showed a variable effect on steroidogenesis. However, when the low dose FSH was combined with adiponectin, estradiol, and progesterone secretion were increased disproportionally to the dose of adiponectin. With the high dose FSH, the positive effect of adiponectin on FSH-induced estradiol secretion was less pronounced, while the effect on progesterone secretion was negligible. This study shows for the first time a stimulatory effect of adiponectin on the secretion of estradiol and progesterone by human luteinized granulosa cells in vitro. It is suggested that adiponectin plays a paracrine role in human ovarian steroidogenesis by sensitizing the granulosa cells to FSH.

Effect of resistin on estradiol and progesterone secretion from human luteinized granulosa cells in culture.

Information on the role of resistin on steroidogenesis is limited to animal studies. The aim of this study was to investigate the effect of various doses of resistin on estradiol and progesterone secretion from human luteinized granulosa cells in culture. Granulosa cells were obtained from follicular fluid aspirated from 50 women undergoing in vitro fertilization (IVF) treatment. The cells were cultured for 48 h after a 24 h pre-incubation period. The effect of resistin at dosages 1, 10 and 100 ng/ml alone or in combinations with FSH (10 and 100 ng/ml) on steroidogenesis was investigated. Estradiol and progesterone were measured by radioimmunoassays in culture supernatants at 24 h and 48 h. FSH treatment increased both estradiol and progesterone secretion. Resistin suppressed basal estradiol (at 1 ng/ml) and progesterone secretion (at all concentrations tested). When resistin (all concentrations) was combined with FSH (100 ng/ml), it eliminated the stimulatory effect of FSH on the secretion of estradiol and progesterone. This study indicates an inhibitory effect of resistin on the secretion of estradiol and progesterone by human luteinized granulosa cells in vitro. It is likely that this adipokine locally affects ovarian function in women. Abbreviations: 3ß-HSD: 3ß-hydroxysteroid dehydrogenase; CAP1: cyclase-associated protein 1; DCN: decorin; FIZZ: Found in Inflammatory Zones; hCG: human chorionic gonadotropin; IGF1: insulin-like growth factor type 1; IVF: in vitro fertilization; PCOS: polycystic ovary syndrome; RIA: radioimmunoassay; ROR1: receptor tyrosine kinase-like orphan receptor-1; TLR4: Toll-like receptor 4.