Isolation and Characterization of Inhibin From Bull Seminal Plasma

Abstract

A simple, short procedure for the isolation of inhibin from bull seminal plasma has been described. Following conversion of the seminal plasma into acetone powder, it was subjected to gel filtration on Sephadex G-100 using 4 m urea\p=m-\0.05 m sodium acetate buffer pH 4.0 as the eluent. Further purification of the active fraction was achieved by 'straight elution analysis' using CM-cellulose. The final preparation (UX) has been shown to reduce the response of immature rat ovaries to human chorionic gonadotrophic hormone (HCG) stimulation in the bioassay system of Chari et al. (1976) and also been shown to suppress the immediate post-castration rise in serum gonadotrophin levels in immature male rats. Homogeneity of the isolated fraction has been assessed electrophoretically at different pH's above and below its isoelectric point. On the basis of gel filtration studies, electrophoresis and amino acid analysis, the molecular weight of UX has been estimated to be 19 000 daltons. The electrophoretic behaviour of UX at an alkaline pH has been discussed as a possible evidence for its existence as isohormones.

Gonadotrophin-inhibiting activity in seminal plasma from intact and vasectomized bulls

“…As yet, we cannot be certain that the gonadotrophin-inhibiting activity observed here is the same as the "bSP-inhibin" described and isolated by Chari et al (1978).…”

“…This gonado¬ trophin-inhibiting activity has some properties in common with the FSH-suppressing activity in bull seminal plasma described by Franchimont et al (1975a) and recently purified and called "bSP-inhibin" by Chari, Duraiswami & Franchimont (1978 Such variation may be due to differences in the methods used to detect FSH and LH suppres¬ sion, or in the material under study. Chari et al (1978) have shown that intravenous injection of freshly prepared "bSP-inhibin" into acutely castrated 35-day-old rats caused suppression of FSH alone, while material which had been stored at -20°C for 6 weeks suppressed both FSH and LH. The seminal plasma samples used in the present study were stored at -20°C for more than 6 weeks before they were used.…”

Synthetic human seminal alpha-inhibin-92 selectively suppresses follicle-stimulating hormone release in vivo.

“…FSH inhibiting substances have been detected in numerous gonadal tissues and fluids of mammals, such as rete testis fluid (4,5), seminal plasma (5)(6)(7)(8), ovarian follicular fluid (9)(10)(11)(12)(13)(14)(15), and media of cultured Sertoli (16,17) and granulosa cells (18). An inhibin-like peptide containing 31 amino acids (a-inhibin-31) was first synthesized and shown to be biologically active in vivo and in vitro (8,19).…”

Effect of Neuraminidase on Inhibin Activity in vivo and in vitro

“…Besides differences in the acid-base and molecular weight characteristics, contradictory evi dence has been reported concerning the gly coprotein nature of inhibin. On one hand it has been claimed that relatively pure inhibin preparations obtained from seminal plasma or testicular extracts contain no sialic acid or other carbohydrate residues and that semipure material obtained from extracts of ham ster ovaries does not bind to concanavalin ASepharose [Chari et al, 1978;Thakur et al, 1978;Chappel ct al., 1979;Sairam, 1981]. On the other hand, some investigators have shown that neuraminidase treatment of in hibin abolishes its biological activity and that inhibin does bind to concanavalin A-Sepharose [Setchell et al, 1977;de Jong et al, 1981;Franchimonl et al, 1982].…”