Research endocrinologists are well aware of inhibin and the family of proteins of which it is a part. Inhibin was discovered almost 70 years ago as a product of the gonads that selectively inhibited the secretion of folliclestimulating hormone (FSH) at the level of the pituitary gland. We now know that inhibin is present in at least two biologically active forms (inhibin A and B) as well as in ...

Inhibin, a member of the TGF-beta superfamily, has been proposed to act as an inhibitor of activin and bone morphogenetic protein (BMP) by sequestering their type II receptors in nonsignaling complexes with betaglycan. This mechanism of inhibin action was tested in a mouse adrenocortical (AC) cell line by examining the effects of inhibins A and B on cytochrome P450 17alpha-hydroxylase 17,20-lya...

This study investigates the effects of spermatogenic germ cells on inhibin -subunit and B-subunit expression, and inhibin -subunit and inhibin B production by rat Sertoli cells in vitro. Sertoli cells isolated from 19-day-old rats were cultured for 48 h at 32 C, in the presence or absence of FSH (2·3–2350 mIU/ml), and in the presence of pachytene spermatocytes, round spermatids or cytoplasts of...

OBJECTIVES It has been suggested that inhibin secretion is altered in women with the polycystic ovary syndrome (PCOS). However, the contribution of a preceding luteal phase has not been taken into account. The aim of the present study was to investigate whether progesterone in the context of a simulated luteal phase affects basal and FSH-induced inhibin secretion in women with PCOS and elevated...

Using new specific and sensitive enzyme-linked immunosorbent assays for inhibin A and inhibin B, we measured these proteins in amniotic fluid (AF), maternal serum (MS), and umbilical cord serum in normal pregnancies. Inhibin A levels in AF rose from a median (10-90th percentile) level of 615 (158.2-1124.6) pg/mL at 14 weeks to 1336.0 (489.4-2084.1) pg/mL at 20 weeks, and inhibin B rose from 216...

Malignant ovarian epithelial tumors have been shown to have decreased inhibin production relative to activin production compared with normal ovarian surface epithelial (OSE) cells and nonmalignant ovarian tumors. Activin stimulates proliferation of many ovarian cancer cell lines. Inhibin antagonizes the action of activin, and inhibin-deficient mice develop gonadal tumors, suggesting that inhibi...

Plasma concentrations of inhibin A and inhibin B during pregnancy and early lactation in chimpanzees were determined by enzyme-linked immunosorbent assay (ELISA). Plasma samples were taken from five pregnant chimpanzees at 6-9, 10, 20 and 25 weeks of pregnancy, and following parturition. Throughout pregnancy and the early postpartum period, circulating inhibin A and inhibin B concentrations rem...

The contribution of specific follicle populations to dimeric inhibin production and inhibin subunit mRNA expression by the rat ovary has been investigated in two model systems, granulosa cells isolated from 25-day-old diethylstilboestrol (DES)-treated rats and post-natal rat ovaries, dispersed in culture or whole ovaries, using specific two-site immunoassays and 'real time' PCR. Media from FSH-...

In a previous study (see Ref.7), the molecular weight distribution of inhibin activity in fractionated human follicular fluid (hFF) and human male and female plasma/serum was determined by in vitro bioassay using ovine pituitary cells in culture and various specific inhibin A and inhibin alpha-subunit-directed immunoassays. It was shown, however, that the ovine in vitro bioassay detected inhibi...

Activin-stimulated FSH synthesis and secretion from the pituitary gonadotrope is negatively modulated by ovarian inhibin; however, the cellular mechanism of inhibin antagonism is unknown. Inhibin and activin share a common beta-subunit through which inhibin can compete with activin for binding to the activin type II receptor and prevent activin signal transduction. Although the affinity of inhi...