Measurement of dimeric inhibin B throughout the human menstrual cycle.

Abstract

This report describes the development of a specific and sensitive assay for inhibin B and its application to the measurement of inhibin B concentrations in plasma during the human menstrual cycle. A monoclonal antibody raised against a synthetic peptide from the betaB-subunit was combined with an antibody to an inhibin alpha-subunit sequence in a double antibody enzyme-linked immunosorbent assay format. The validated assay had a limit of detection of 10 pg/mL and 0.5% cross-reactivity with inhibin A. Using this immunoassay, we found that the plasma concentration of inhibin B rose rapidly in the early follicular phase to a peak of 85.2 +/- 9.6 pg/mL on the day after the intercycle FSH rise, then fell progressively during the remainder of the follicular phase. Two days after the midcycle LH peak, there was a short lived peak in the inhibin B concentration (133.6 +/- 31.2 pg/mL), which then fell to a low concentration (<20 pg/mL) for the remainder of the luteal phase. In contrast, the inhibin A concentration was low in the early follicular phase, rose at ovulation, and was maximal during the midluteal phase. The concentration of inhibin B in individual follicular fluid samples was 20- to 200-fold higher than the concentration of inhibin A and was highest in follicular fluid samples from the early follicular phase. Inhibin B appears to be the predominant form of inhibin in the preovulatory follicle. The different patterns of circulating inhibin B and inhibin A concentrations observed during the human menstrual cycle suggest that these forms may have different physiological roles.

Multiple Stable Periodic Solutions in a Model for Hormonal Control of the Menstrual Cycle

“…For instance, the data of McLachlan et al (1990) were collected before the assay distinguishing inhibin A and inhibin B was available. With data for inhibin A and B now in the literature (Groome et al, 1996) both should be included in the model. The inhibin profile in the present model is similar to inhibin A while inhibin B is prominent during the follicular phase of the cycle.…”

Luteal-phase inhibin A and follicular-phase inhibin B levels are not characteristic of patients with an elevated LH-to-FSH ratio

“…Inhibins are gonadally derived heterodimeric glycoprotein hormones, which are built up from an α and one of two partially homologous β subunits, β A or β B , giving rise to the two isoforms inhibin A and inhibin B. Inhibin B levels increase from the early follicular phase to reach a peak coinciding with the onset of the midfollicular phase decline in FSH levels and then decrease during the luteal phase apart from a periovulatory peak [4]. This suggests inhibin B secretion by the developing small antral follicles.…”

Relationship between apoptotic markers in semen from fertile men and demographic, hormonal and seminal characteristics

“…Inhibin B levels were assessed using a specific immunometric method, as previously described, with a detection limit of 15 ng l 21 and intra-assay and total assay variation coefficients ,7%. 20,21 All assays were performed at Malmö University Hospital (Sweden) after completion of sample collection.…”