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Somatostatin
Identifiers
Symbols SST; SMST
External IDs OMIM182450 MGI98326 HomoloGene819 GeneCards: SST Gene
RNA expression pattern
PBB GE SST 213921 at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 6750 20604
Ensembl ENSG00000157005 ENSMUSG00000004366
UniProt P61278 Q545V6
RefSeq (mRNA) NM_001048 NM_009215
RefSeq (protein) NP_001039 NP_033241
Location (UCSC) Chr 3:
188.87 - 188.87 Mb
Chr 16:
23.8 - 23.81 Mb
PubMed search [1] [2]

Somatostatin (also known as growth hormone-inhibiting hormone (GHIH) or somatotropin release-inhibiting factor (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]

Contents

Production

Digestive system

Somatostatin is secreted in several locations in the digestive system:

Brain

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.

Actions

D cell is visible at upper-right, and somatostatinis represented by middle arrow pointing left

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

Synthetic substitutes

Octreotide (brand name Sandostatin, Novartis Pharmaceuticals) is an octapeptide that mimics natural somatostatin pharmacologically, though is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone and has a much longer half-life (approximately 90 minutes, compared to 2-3 minutes for somatostatin). Since it is absorbed poorly from the gut, it is administered parenterally (subcutaneously, intramuscularly, or intravenously). It is indicated for symptomatic treatment of carcinoid syndrome, acute variceal bleeding, and acromegaly. It is also finding increased use in polycystic diseases of the liver and kidney.

Lanreotide (INN) is a medication used in the management of acromegaly and symptoms caused by neuroendocrine tumors, most notably carcinoid syndrome. It is a long-acting analogue of somatostatin, like octreotide.

Lanreotide(as lanreotide acetate) is manufactured by Ipsen, and marketed under the trade name Somatuline. It is available in several countries, including the United Kingdom, Australia, and Canada, and was approved for sale in the United States by the Food and Drug Administration (FDA) on August 30, 2007.

References

  1. ^ a b Costoff A. "Sect. 5, Ch. 4: Structure, Synthesis, and Secretion of Somatostatin". Endocrinology: The Endocrine Pancreas. Medical College of Georgia. pp. page 16. http://www.lib.mcg.edu/edu/eshuphysio/program/section5/5ch4/s5ch4_16.htm. Retrieved 2008-02-19. 
  2. ^ Costanzo, Linda S. (2003). Physiology (3rd ed.). Hagerstown, MD: Lippincott Williams & Wilkins. pp. 280. ISBN 0-7817-3919-5. 
  3. ^ a b Bowen R (2002-12-14). "Somatostatin". Biomedical Hypertextbooks. Colorado State University. http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/somatostatin.html. Retrieved 2008-02-19. 
  4. ^ a b Costoff A. "Sect. 5, Ch. 4: Structure, Synthesis, and Secretion of Somatostatin". Endocrinology: The Endocrine Pancreas. Medical College of Georgia. pp. page 17. http://www.lib.mcg.edu/edu/eshuphysio/program/section5/5ch4/s5ch4_17.htm. Retrieved 2008-02-19. 

Further reading








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