Nature and Mechanisms of Action of Inhibin: Perspective in Regulation of Male Fertility

Abstract

Inhibin extracted from human seminal plasma and from rete testis fluid is a protein substance. Two forms of inhibin exist in RTF and each has a different molecular weight. The species of higher molecular weight systematically yields a product of lower molecular weight during chromatography. This phenomenon could represent depolymerization of the molecule, an associated transport protein or alternatively a precursor form of inhibin. The inhibin preparations utilized selectively lowered the levels of FSH as assessed both in vivo and in vitro. This action was not totally specific since increasing doses of inhibin also produced a lowering of the levels of LH. In contrast, these preparations did not influence the secretion of TSH, growth hormone or prolactin in vivo or in vitro. A direct effect of inhibin on pituitary cells has been clearly established by demonstrating a reduction in the release of FSH in response to GnRH and its synthesis in the pituitary cells. Additional direct effects on the hypothalamus and on gametogenesis in the testis remain to be excluded. On the basis of selective effects of inhibin on FSH secretion, one could envisage the utilization of this hormone as an antifertility agent.

The role of follicle stimulating hormone in testicular function of the mature rhesus monkey

“…This gives a further example that results ob¬ tained in small rodents may not necessarily reflect the situation in the primate, and that each species requires separate investigation. These results also provide a valuable incentive to explore further the possibilities of selective suppression of FSH, for example with inhibin (Franchimont et al 1978) or with steroids (Neumann et al 1978), for the regula¬ tion of male fertility.…”

Functional Relationships of the Mammalian Testis and Epididymis

“…The substance was named 'inhibin' by McCullagh (1932) and several laboratories in recent years have contributed new knowledge about its source, identity and possible function (see Setchell et al 1977;Hudson et al 1979;Main et al 1979;Sheth et al 1979). Rete testis fluid from rams has been shown to contain proteins which, when isolated and fractionated, are capable of dose-related inhibition of FSH secretion by pituitary cells in culture (Franchimont et al 1978). However, high concentrations of these fractions also depress LH secretion and there are indications that ram rete testis fluid contains proteins which may also depress LH secretion when injected into cryptorchid ranis which have raised FSH and LH levels (Cahoreau et al 1979).…”

L'Inhibine

“…Cependant, nous avons montré (Blanc et al,1978;Cahoreau et al,1979) (Baker et al, 1976 ; Steinberger, 1976 ;Erickson et Hsueh, 1978 ;de Jong et al,1978de Jong et al, ,1979aLabrie et al, 1978 (Baker et al, 1976 ;Franchimont et al, 1978 ;de Jong et al, 1978 ;Labrie et al, 1978 ;Hudson et al, 1979) (Lugaro et ai., 1969(Lugaro et ai., , 1973(Lugaro et ai., , 1974 Dacheux, 1976 ;Baker et al, 1976Baker et al, ,1978Davies et al, 1976Davies et al, , 1978Franchimont et al, 1977Franchimont et al, , 1978 Franchimont, 1976 Main, 1977a ;humain : Franchimont et al, 1973humain : Franchimont et al, ,1975ahumain : Franchimont et al, , b, 1977humain : Franchimont et al, , 1978Thakur et al, 1978 ;Chari et al, 1979) Lugaro et al,1973 ; Demoulin, 1975a ;Baker et al, 1976 ;papaïne : Cahoreau et al, 1979) ou par les traitements thermiques supérieurs à 65 °C (Lugaro et al,1973 ;Baker et al,1976 ;Setchell, Davies et Main, 1977a ; (Vaughan, 1978). Cependant, l'arginine vasotocine ne modifie pas la sécrétion des gonadotropines de rat in vitro (Moskowska et Ebels, 1968 ;…”