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Symbol SST
Entrez 6750
HUGO 11329
OMIM 182450
RefSeq NM_001048
UniProt P61278
Other data
Locus Chr. 3 q28

Somatostatin (also known as growth hormone inhibiting hormone (GHIH) or somatotropin release-inhibiting hormone (SRIF)) is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones.

Somatostatin has two active forms produced by alternative cleavage of a single preproprotein: one of 14 amino acids, the other of 28 amino acids.[1]



Digestive system

Somatostatin is secreted in several locations in the digestive system:


Somatostatin is produced by neuroendocrine neurons of the periventricular nucleus of the hypothalamus. These neurons project to the median eminence, where somatostatin is released from neurosecretory nerve endings into the hypothalamo-hypophysial portal circulation. These blood vessels carry somatostatin to the anterior pituitary gland, where somatostatin inhibits the secretion of growth hormone from somatotrope cells. The somatostatin neurons in the periventricular nucleus mediate negative feedback effects of growth hormone on its own release; the somatostatin neurons respond to high circulating concentrations of growth hormone and somatomedins by increasing the release of somatostatin, so reducing the rate of secretion of growth hormone.

Somatostatin is also produced by several other populations that project centrally - i.e. to other areas of the brain, and somatostatin receptors are expressed at many different sites in the brain. In particular, there are populations of somatostatin neurons in the arcuate nucleus, the hippocampus and the brainstem nucleus of the solitary tract.



Somatostatin is classified as an inhibitory hormone,[1] whose actions are spread to different parts of the body:

Anterior pituitary

In the anterior pituitary gland, the effects of somatostatin are:

Gastrointestinal system

  • Suppress the release of gastrointestinal hormones
  • Lowers the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within the intestine[3]
  • Suppress the release of pancreatic hormones
  • Suppress the exocrine secretory action of pancreas.

Synthetic substitutes

Octreotide (brand name Sandostatin, Novartis Pharmaceuticals) is an octopeptide that mimics natural somatostatin pharmacologically, though is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone.


  1. ^ a b Physiology at MCG 5/5ch4/s5ch4_16
  2. ^ Costanzo, LS. Board Review Series: Physiology 3rd Ed. Lippincott, Williams & Wilkins. 2003. p. 280.
  3. ^ a b Colorado State University - Biomedical Hypertextbooks - Somatostatin
  4. ^ a b Physiology at MCG 5/5ch4/s5ch4_17
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Somatostatin". A list of authors is available in Wikipedia.
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