Endocrinology: Serum concentrations of dimeric inhibin during the spontaneous human menstrual cycle and after treatment with exogenous gonadotrophin

Abstract

A recently described two-site enzyme immunoassay incorporating a pre-assay oxidation step was validated and used to measure serum concentrations of dimeric inhibin in five normally cycling women and in 13 women undergoing gonadotrophin therapy. Recombinant human inhibin A (standard) gave an assay response curve which was parallel to those for human serum samples and recovery of exogenous inhibin added to serum samples before assay was quantitative (109 +/- 8%, n = 11). During the normal menstrual cycle dimeric inhibin concentration increased from 9.0 +/- 2.0 pg/ml during the early follicular phase to reach a mid-cycle peak of 55.3 +/- 11.1 pg/ml coincident with the pre-ovulatory gonadotrophin surge. After falling to 27.9 +/- 5.7 pg/ml 1 day after the luteinizing hormone surge, inhibin then rose in parallel with serum progesterone to reach a peak value of 115.6 +/- 19.3 pg/ml during the mid-luteal phase, before falling to 14.1 +/- 4.9 pg/ml by the onset of next menses. During the follicular phase, dimeric inhibin concentrations were closely correlated with those of serum oestradiol (r = 0.69; P < 0.001), whereas during the luteal phase they were most closely correlated with serum progesterone concentrations (r = 0.73; P < 0.001). Daily treatment with human menopausal gonadotrophin promoted a progressive increase in serum dimeric inhibin concentration which increased approximately 20-fold in 6 days. In the same period total alpha-inhibin (measured by radioimmunoassay) increased approximately 5-fold, while serum oestradiol increased approximately 30-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic changes in messenger RNAs encoding inhibin/activin subunits in the ovary of the golden hamster (Mesocricetus auratus)

“…The changing pattern of plasma inhibin B in the golden hamster was very similar to that in the rat. However, plasma concentrations of inhibin A showed a striking rise during the preovulatory period (Ohshima et al 1999), which was not observed in rats (Woodruff et al 1996, cows (Kaneko et al 2002) and humans (Muttukrishna et al 1994). Although these data suggest that the golden hamster ovary would show a unique changing pattern of A-subunit mRNA during the preovulatory period, cyclic changes in levels and distribution patterns of inhibin/activin subunit mRNAs in the golden hamster ovary remain unknown.…”

Predictors of ovarian reserve in young women with breast cancer

“…Inhibin A: Serum concentrations of dimeric inhibin A were measured in duplicate 50 ml aliquots as described previously (Muttukrishna et al, 1994). The sensitivity of the assay was 2 pg ml À1 and the intra-and interassay variations were o6%.…”

Attenuin: What It Is, How It Works and What It Does

“…The ovarian origin of attenuin was confirmed when Fowler et al (2002), culturing theca, stroma and granulosa cells from cyclic women, showed that attenuin bioactivity was present only in granulosa-cell-conditioned medium. Use of a superovulated protocol as a model for increased attenuin bioactivity posed a number of problems, including elevated peripheral estradiol and inhibin levels during gonadotropin administration (de Jong, 1988;Messinis & Templeton, 1988; www.intechopen.com Muttukrishna et al, 1994), which raised doubts as to the origin of this bioactivity. With regard to estradiol, studies carried out in women have proved that effects on LH secretion are not due to negative feedback: Messinis et al (1991Messinis et al ( , 1993 demonstrated that a single FSH injection had dose-dependent suppressive effects on pituitary responsiveness to exogenous GnRH pulses.…”