Activin inhibition of estradiol and progesterone production in porcine granulosa cells.
1997
Ford J.J. | Howard H.J.
Two studies evaluated the influence of activin on steroidogenesis in cultured porcine granulosa cells obtained at various stages of differentiation. In granulosa cells isolated from 1- to 3-mm follicles, obtained at random stages of the estrous cycle, treatment with activin or transforming growth factor beta (TGFbeta) decreased progesterone production during the first 48 h of culture, but neither had an effect on estradiol production. One-half of these cells received FSH treatment at 48 h, and at 96 and 144 h of culture FSH increased estradiol and progesterone production. Activin or TGFbeta reduced, in a dose-dependent manner, both basal and FSH-stimulated production of both steroids. In the second study, granulosa cells were obtained during follicular growth associated with weaning and were separated into two subpopulations (weakly associated [WA] and tightly bound [TB]). Estradiol production in culture increased with time after weaning. Tightly bound cells produced more estradiol than WA cells and maintained FSH-stimulated estradiol production, whereas production of progesterone increased in both cell types after treatment with FSH. Activin depressed FSH-stimulated estradiol production in TB cells and depressed FSH-stimulated progesterone production in both cell types. These results clearly indicate that activin depresses in vitro steroidogenesis by granulosa cells from antral, porcine follicles; thus, activin may participate in atresia of antral follicles of this species.
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