Isolation of inhibin like peptides from human placenta

Two moieties of inhibin could be obtained by chromatography of partially purified preparations of inhibin from human placenta on Sephadex G-100, G-25 and ion exchange chromatography on diethylaminoethyl Sephadex A-50. The higher molecular weight moiety (14,000) designated as HPI-H appears to be similar to inhibin from human seminal plasma. While the lower molecular weight moiety (1500) designated as HPI-L appears to be similar to that of sheep testicular inhibin. The preparations from both human term placenta and human seminal plasma inhibited the binding of [125I] human follicle stimulating hormone to rat testicular receptors. This effect of inhibins could be neutralized by antisera raised against corresponding polypeptide. Further these antibodies could neutralize endogenous inhibin resulting in 2 to 3 fold increase in serum follicle stimulating harmone levels, which could then be reversed by exogenous administration of the isolated inhibin preparations

Potential application of inhibin in male and female contraception

After a review of investigations into the possible use of inhibin in the regulation of male and female fertility, briefly described and summarized in this article, the authors conclude that, at least in experimental animals, inhibin causes a significant reduction in testicular and epididymal spermatozoa in the male and luteal phase defect in the female. The precise mechanism by which inhibin brings about these effects is not known at present, and its elucidation will greatly help in the more effective use of inhibin

Comparative evaluation of three methods for extraction of gonadotrophins from buffalo pituitaries

This article does not have an abstract

Localization of inhibin in testes of human, bonnet monkey, dog and rat by immunoperoxidase technique

Immunocytochemical study on the localization of inhibin in the testes of human, bonnet monkey, dog and rat was carried out using indirect immunoperoxidase technique, in order to investigate the cell types involved in inhibin production/storage. A positive reaction was observed in the testes of human, monkey and dog while it was negative in rat testis using specific antiserum to human testicular inhibin generated against homogeneous preparation of human testicular inhibin in our laboratory. Inhibin was found to be localized in Sertoli cells, spermatogonia and primary spermatocytes of human, monkey and dog testes. A weak positive reaction was observed in spermatids of human testis only. Interestingly, Leydig cells of human, monkey and dog testes showed positive reaction indicating presence of inhibin in these cells also

An enzyme-linked immunosorbent assay for the detection of human seminal plasma inhibin

A simple and sensitive enzyme-linked immunosorbent assay (ELISA) is described for the measurement of inhibin in urine and seminal plasma. Standards used cover a range from 50 ng to 0.05 ng/0.1 ml with a detection limit of 0.098 ng/0.1 ml. Coefficients of variation for intra-assay precision and for inter-assay precision were obtained and compared favourably with RIA. Given the ease of application, this technique is an useful alternative to existing radioimmuno-assays for this peptide

Binding of radio iodinated human placental lactogen to buffalo corpus luteum in vitro

Binding of human placental [125I]lactogen to homogenates of the buffalo CL was studied. Differential centrifugation studies revealed the existence of hormone-binding components in fractions of the CL homogenate sedimenting at 800 g, 10,000 g and 100,000 g. The binding was affected by incubation time and hormone concentration. The hormone-binding components were heat-labile and susceptible to proteolytic enzymes

Inhibin: unity in diversity

Historically, inhibin was thought to be a testicular hormone involved in the regulation of pituitary FSH by a negative feedback control. The ability of inhibin to preferentially suppress FSH without affecting LH triggered extensive research for its possible use as a male contraceptive, suggesting a plurality of molecular forms and a multiplicity of biological actions of this putative hormone. It also became evident that inhibin is not unique to the testis, as presumed earlier, and can even be obtained from the ovary. This has necessitated a fundamental revision of the original concept of inhibin. Unfortunately, not many perceive inhibin as a loose conglomerate of structurally dissimilar, FSH-suppressing proteins and insist on singling out a 32-kDa protein derived from ovarian follicular fluid to be designated as inhibin. This article highlights features common to two distinctly different types of inhibin: seminal inhibin and ovarian inhibin. Evidence is also provided to indicate that the term inhibin need not be specific to the ovarian protein, but encompasses proteins hitherto dismissed as inhibin-like or inhibin-related proteins

On the mechanism of action of low molecular weight inhibin from ram testes

This article does not have an abstract

Measurement of inhibin

The bioassays developed so far, although good for detecting inhibin from different sources and for monitoring their purification, are not really practical for physiological studies. Moreover, they are influenced by steroidal hormones. In this regard radioimmunoassays, with their high capacity and greater sensitivity, are of immense value in studies involving the physiology of inhibin. More information on this aspect will probably lead to the development of more rational methods of assay. However, the need for an international reference preparation that will provide a common basis for comparing data from different laboratories cannot but be emphasized

Inhibition of hypothalamic GnRH synthesis by inhibin

Both testicular and ovarian inhibin preparations blocked GnRH synthesis by the hypothalamus and consequently reduced the circulating level of FSH. The serum level of LH was unaffected