Inhibin

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inhibin, alpha
Identifiers
Symbol(s)	INHA
Entrez	3623
OMIM	147380
RefSeq	NM_002191
UniProt	P05111
Other data
Locus	Chr. 2 q33-qter

inhibin, beta A (activin A, activin AB alpha polypeptide)
Identifiers
Symbol(s)	INHBA
Entrez	3624
OMIM	147290
RefSeq	NM_002192
UniProt	P08476
Other data
Locus	Chr. 7 p15-p13

inhibin, beta B (activin AB beta polypeptide)
Identifiers
Symbol(s)	INHBB
Entrez	3625
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, and participates in the regulation of the menstrual cycle.

Contents 1 Structure 2 Action 3 Activin 4 Prenatal Testing 5 External links 6 References

[edit] Structure

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) family.

[edit] Action

In women, FSH stimulates the secretion of inhibin from the granulosa cells of the 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, in contrast to inhibin A, which reaches its peak in the mid-luteal phase. Inhibin is produced in the gonads, pituitary gland, placenta and other organs.

In men, it is a hormone that inhibits FSH production. It is secreted from the sustentacular cell, located in the seminiferous tubule inside the testes.

[edit] Activin

Activin is a related peptide that counteracts inhibin.

[edit] Prenatal Testing

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 ^[1] suggestive of the presence of a fetus with Downs syndrome. As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.

[edit] External links

• http://www.inhibin.com

[edit] References

1. ^ (1996-05-09) "Dimeric Inhibin A as a Marker for Down's Syndrome in Early Pregnancy". New England Journal of Medicine, The 334 (19): 1231-1236. Retrieved on 2006-08-04.

Hormones and endocrine glands - edit

Hypothalamus: - TRH - CRH - GnRH - GHRH - somatostatin - dopamine | Posterior pituitary: vasopressin - oxytocin - lipotropin | Anterior pituitary: GH - ACTH - TSH - LH - FSH - prolactin - MSH - endorphins - lipotropin Thyroid: T3 and T4 - calcitonin | Parathyroid: PTH | Adrenal medulla: epinephrine - norepinephrine | Adrenal cortex: aldosterone - cortisol - DHEA | Pancreas: glucagon- insulin - somatostatin | Ovary: estradiol - progesterone - inhibin - activin | Testis: testosterone - AMH - inhibin | Pineal gland: melatonin | Kidney: renin - EPO - calcitriol - prostaglandin | Heart atrium: ANP Stomach: gastrin | Duodenum: CCK - GIP - secretin - motilin - VIP | Ileum: enteroglucagon | Liver: IGF-1 Placenta: hCG - HPL - estrogen - progesterone Adipose tissue: leptin, adiponectin Target-derived NGF, BDNF, NT-3