Dexamethasone or triamcinolone increases follicular development in immature female rats

We have previously reported that dexamethasone increased follicle-stimulati ng hormone (FSH) secretion via suppression of inhibin in immature female ra ts. In the present study, we investigated the effects of dexamethasone or t riamcinolone on follicular development and ovarian functions (estradiol and inhibin secretion) in equine chorionic gonadotropin (eCG)-primed immature female rats. Dexamethasone significantly increased the number of ovulated o ocytes in immature female rats treated with 5 i.u. eCG. Serum concentration of FSH in eCG-treated female rats was increased by administration of dexam ethasone or triamcinolone, showing the peak value at 9 h after its administ ration, although the levels of inhibin markedly decreased at that time. Ser um concentrations of inhibin and estradiol in eCG-treated female rats incre ased at 24 h after administration of dexamethasone or triamcinolone. These results demonstrate that dexamethasone or triamcinolone increases FSH secre tion, and the excess amount of FSH strongly stimulates follicular developme nt cooperating with exogenous eCG.