What, as Gynaecologist we need to know on Inhibin-B?
Inhibin is a dimeric glycoprotein complex
that suppresses the secretion of FSH
by the pituitary gland. Inhibins are hormones
secreted by granulosa cells of the ovary in the female and Sertoli cells of the
testis in the male. They selectively suppress the secretion of pituitary
follicle stimulating hormone (FSH) and also have local paracrine actions in the
gonads. The inhibins consist of a dimer of 2 homologous subunits, an alpha
subunit and either a beta A or beta B subunit, to form inhibin A and inhibin B,
respectively. Inhibin-b are produced
by the 1) gonads by Sertoli cells in particular in men and 2) by granulosa
cells in women. Inhibin plays a vital role in controlling the production of
gametes and embryonic and the foetal development. They
selectively suppress the secretion of pituitary follicle stimulating hormone
(FSH) and also have local paracrine actions in the gonads.
Reference Values
Males:
<2.0 pg/mL
Females
<11
years: <4.7 pg/mL
11-17
years: <97.5 pg/mL
Premenopausal:
<97.5 pg/mL
Postmenopausal:
<2.1 pg/mL
The inhibins consist of a dimer of 2 homologous subunits,
an alpha subunit and either a beta A or beta B subunit, to form inhibin A and
inhibin B, respectively.
In females, inhibin A
is primarily produced by the dominant follicle and corpus luteum: whereas
inhibin B is predominantly produced by small developing follicles. Serum
inhibin A and B levels fluctuate during the menstrual cycle. At menopause, with
the depletion of ovarian follicles, serum inhibin A and B decrease to very low
or undetectable levels. Inhibins are glycoproteins produced by the
granulosa and theca cells of the ovary and belong to the superfamily of
transforming growth factors-β (TGFs-β). Role of inhibin includes
suppression of FSH production from the pituitary. Levels of inhibit
B vary with exogeneous GnRH or FSH stimulation and also between menstrual
cycles. Levels are lower (<45 pg/ml) in women who are poor responders. Women
with reduced ovarian reserve have reduced values of estradiol (E2) up to 50
pg/ml. When measured along with basal FSH, increased day 3 estradiol
reflects a poor response to ovarian stimulation. Early elevation of estradiol
reflects the advanced follicular development and early selection of dominant
follicle.
No comments:
Post a Comment