Follicle-stimulating hormone–testosterone interaction in modulating steroidogenesis in bovine granulosa cells. I. Effect on progesterone production

Abstract

Grasselli F, Basini G, Bussolati S, Tamanini C. Follicle-stimulating hormone–testosterone interaction in modulating steroidogenesis in bovine granulosa cells. I. Effect on progesterone production. Eur J Endocrinol 1995;132:759–64. ISSN 0804–4643 The aim of this study was to investigate the effects of testosterone on basal and follicle-stimulating hormone (FSH)-induced progesterone production by cultured bovine granulosa cells. Granulosa cells were isolated from small (< 5 mm) and large (>8 mm) follicles and cultured for 48 h in 1 ml of Medium-199 with different concentrations of FSH (0.1, 1, 10 and 35 mg/l). In addition, the combined effects of different amounts of testosterone (1 nmol–10 μmol) and 1 mg/l FSH for 48 h on progesterone production by granulosa cells of both groups of follicles were studied; progesterone production during the subsequent 24-h incubation period was evaluated in the absence of hormones. In a third experiment, granulosa cells were treated with 500 μg of dibutyryl-cAMP and 10 μmol of testosterone for 48 h. At the end of each incubation period, the progesterone content in the culture media was determined by a validated radioimmunoassay. Basal progesterone release during the 48-h incubation period was higher in granulosa cells from small as compared to cells from large follicles; in both groups of cells, progesterone production was stimulated maximally by 1 mg/l FSH. The treatment with 10 μmol of testosterone induced a decrease of progesterone production in both groups of cells, while lower amounts exerted an inhibitory effect only in cells from large follicles. Furthermore, 10 μmol of testosterone inhibited FSH-induced progesterone release, while lower dosages were ineffective. Dibutyryl-cAMP stimulated significantly the progesterone output by granulosa cells of both groups and testosterone was effective in suppressing this increase. Our data demonstrate that testosterone plays an important role in regulating progesterone production by granulosa cells in that it inhibits (at high dosages) both basal and FSH-induced progesterone output. These data also suggest that the site of inhibition is distal to cAMP formation. Carlo Tamanini, Istituto di Fisiologia Veterinaria. Via del Taglio 8, 43100 Parma, Italy