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inhibin, alpha
Symbol INHA
Entrez 3623
HUGO 6065
OMIM 147380
RefSeq NM_002191
UniProt P05111
Other data
Locus Chr. 2 q33-qter
inhibin, beta A (activin A, activin AB alpha polypeptide)
Symbol INHBA
Entrez 3624
HUGO 6066
OMIM 147290
RefSeq NM_002192
UniProt P08476
Other data
Locus Chr. 7 p15-p13
inhibin, beta B (activin AB beta polypeptide)
Symbol INHBB
Entrez 3625
HUGO 6067
OMIM 147390
RefSeq NM_002193
UniProt P09529
Other data
Locus Chr. 2 cen-q13

Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion,[1] and participates in the regulation of the menstrual cycle.



Inhibin contains an alpha and beta subunit linked by disulfide bonds. Two forms of inhibin differ in their beta subunits (A or B), while their alpha subunits are identical.

Inhibin belongs to the transforming growth factor-β (TGF-β) superfamily.


In both females and males, inhibin inhibits FSH production. However, the overall mechanism differs between the genders:

In females

In women, FSH stimulates the secretion of inhibin from the granulosa cells of the ovarian follicles in ovary. In turn, inhibin suppresses FSH.

Inhibin secretion is diminished by GnRH, and enhanced by insulin-like growth factor-1 (IGF-1).

  • Inhibin B reaches a peak in the early- to mid-follicular phase, and a second peak at ovulation.
  • Inhibin A reaches its peak in the mid-luteal phase.

Inhibin is produced in the gonads, pituitary gland, placenta and other organs.

In males

In men, it is a hormone that inhibits FSH production.

It is secreted from the Sertoli cells,[2] located in the seminiferous tubule inside the testes.


Activin is a related peptide that counteracts inhibin.

Clinical significance

Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16-18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is[3] suggestive of the presence of a fetus with Down's syndrome. As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.

It also has been used as a marker for ovarian cancer.[4][5]


  1. ^ van Zonneveld P, Scheffer G, Broekmans F, Blankenstein M, de Jong F, Looman C, Habbema J, te Velde E (2003). "Do cycle disturbances explain the age-related decline of female fertility? Cycle characteristics of women aged over 40 years compared with a reference population of young women". Hum Reprod 18 (3): 495-501. PMID 12615813.
  2. ^ Skinner M, McLachlan R, Bremner W (1989). "Stimulation of Sertoli cell inhibin secretion by the testicular paracrine factor PModS". Mol Cell Endocrinol 66 (2): 239-49. PMID 2515083.
  3. ^ Aitken D, Wallace E, Crossley J, Swanston I, van Pareren Y, van Maarle M, Groome N, Macri J, Connor J (1996). "Dimeric inhibin A as a marker for Down's syndrome in early pregnancy". N Engl J Med 334 (19): 1231-6. PMID 8606718.
  4. ^ Robertson D, Pruysers E, Jobling T. "Inhibin as a diagnostic marker for ovarian cancer". Cancer Lett. PMID 17320281.
  5. ^ Robertson D, Pruysers E, Burger H, Jobling T, McNeilage J, Healy D (2004). "Inhibins and ovarian cancer". Mol Cell Endocrinol 225 (1-2): 65-71. PMID 15451569.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Inhibin". A list of authors is available in Wikipedia.
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