Male and Female Inhibin

Abstract

The testis and ovary secrete a nonsteroidal hormone that selectively inhibits pituitary FSH secretion. Inhibin, a polypeptide hormone produced by Sertoli cells in the seminiferous tubules and by the granulosa cells of the ovarian follicle, is isolated from seminal fluid, rete testis fluid testicular and ovarian extracts, and follicular fluid. There may be two forms of inhibin. a form of higher molecular weight (> 10,000 daltons) being the precursor of a low-moleculay-weight form (>5,000 daltons). The functional integrity of inhibin is destroyed by trypsin or pepsin digestion and exposure to heat. This induces the formation of antibodies that are able to neutralize endogenous inhibin when injected into adult males or females. Apart from its main action at the pituitary level, inhibin could also function at the hypothalamus or directly at the gonad. Inhibin inhibits the release of FSH and to a lesser extent of LH induced by exogenous GnRH in vivo and in vitro. Inhibin reduces the endogenous GnRH content of hypothalami maintained in organ culture. These reactions have been utilized in the development of in vivo and in vitro assay methods. It is feasible that inhibin is involved in the regulation of the ovarian cycle, and that this hormone plays a more important role in the feedback regulation of FSH in the adult female than in the adult male.

On the Negative Feedback Regulation of Gonadotropins in Castrate and Intact Cattle with Comparison of Two FSH Radioimmunoassays1

“…However, in addition to estrogen and progesterone, regulation of FSH in sheep appears to involve another ovarian factor such as inhibin (Goodman et al, 1981a). It can be speculated that this is also the case in cattle (Hafez, 1980), where the presence of this factor in the circulation may provide an alternative explanation for the delayed FSH response. If true, the effect of inhibin is relatively long.…”

Stimulation of ornithine decarboxylase in the rat prostate by seminal plasma inhibin

“…The regulation of pituitary secretion of FSH by the negative feedback effect of gonadal inhibin is well established (Hudson et al 1979; Davies et al 1978). Several peptides with inhibin-like activity, but differing in sue and purification pattern have been detected in extracts of the gonads (Franchimont et al 1979;deJong 1979;Hafez 1980). These materials show biological effects of either selectively inhibiting the synthesis and/or the secretion of pituitary FSH.…”

Control of Spermatogenesis in Primate and Prospect of Male Contraception

“…These changes are under the control of pituitary FSH and LH regulated by hypothalamus gonadotrophin releasing hormone and testicular paracrine= autocrine factors [20,21,38,63]. Sperm production depends on the concerted action of FSH and testosterone on the testis [21,68]. Local 78 Y.-X.…”

“…Local 78 Y.-X. Liu testicular paracrine factor inhibin may play an important role in spermatogenesis [21,52].…”