Inhibin production by bovine ovarian tissues in vitro and its regulation by androgens

Abstract

No detectable amounts of inhibin were produced by cultured ovarian stroma or luteal tissue. Follicular tissue produced inhibin in vitro and removal of the granulosa cells from the follicle wall caused inhibin production to fall by 80%. Granulosa cells alone had the greatest ability of any ovarian cell type to produce inhibin in vitro, and are probably the major site of follicular inhibin production. Cyproterone acetate at concentrations of 35 and 350 .mu.M inhibited basal and testosterone (3-5 .mu.M)-stimulated inhibin production by cultured intact follicle wall and granulosa cells. In addition, each concentration of cyproterone acetate inhibited progesterone but not estradiol-17.beta. production by the follicle wall and granulosa cell cultures. The synthetic, non-aromatizable androgens, methylestrenolone and mesterolone, at concentrations of 5 and 25 .mu.M, mimicked the effect of testosterone and stimulated granulosa cell inhibin production, methylestrenolone being the more potent. Androgens evidently regulate follicular inhibin and progesterone production and these may be receptor-mediated processes, inhibin production may be a general property of androgenic compounds. Preliminary examination of the physicochemical characteristics of inhibin indicated that the inhibin activity of bovine granulosa cell culture medium was retained by an Amicon XM100A filter with a nominal MW cut-off point of 100,000; and destroyed by heating to 80.degree. C for 30 min.