Dexamethasone increases follicle-stimulating hormone secretion via suppression of inhibin in rats

in the present study, the effects of dexamethasone on follicle-stimulating hormone (FSH) secretion in immature female rats were investigated. Dexameth asone increased the selective secretion of FSH and decreased plasma concent rations of inhibin in immature female rats. The effects of dexamethasone on FSH secretion were not confirmed in rats treated with ovariectomy or immun oneutralization against inhibin. In addition to the direct effect of dexame thasone on FSH synthesis in gonadotrophs, the present study has clearly dem onstrated that the increased level of FSH in dexamethasone-treated rats is mediated by suppression of ovarian function, especially by the inhibition o f inhibin secretion. (C) 1999 Elsevier Science B.V. All rights reserved.