Somatostatin

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Somatostatin
Somatostatin

Existing structural data : 1P2W , 2MI1

Properties of human protein
Mass / length primary structure 14 and 28 amino acids, respectively
Precursor 92 amino acids
Identifier
Gene names SST  ; SMS; SMST; GHIH
External IDs
Occurrence
Homology family Somatostatin
Parent taxon Euteleostomi
Orthologue
human House mouse
Entrez 6750 20604
Ensemble ENSG00000157005 ENSMUSG00000004366
UniProt P61278 P60041
Refseq (mRNA) NM_001048 NM_009215
Refseq (protein) NP_001039 NP_033241
Gene locus Chr 3: 187.67 - 187.67 Mb Chr 16: 23.89 - 23.89 Mb
PubMed search 6750 20604

Somatostatin is a peptide hormone in vertebrates that is secreted by the pancreas during digestion and, as an inhibiting hormone of the hypothalamus, inhibits the formation of the growth hormone somatropin in the pituitary gland . This is where the synonym somatotropin (release) -inhibiting hormone (SIH or SRIH) or growth hormone (release) -inhibiting hormone (GHIH or GHRIH) comes from. It also takes part in signal transduction when initiating apoptosis . Synthetic analogues of somatostatin are lanreotide , pasireotide and octreotide , which are approved as medicinal substances . A peptide formerly known as bulbogastron is likely identical to somatostatin.

Somatostatin is not only produced by the δ cells of the pancreas, but also by individual cells of the hypothalamus and the gastrointestinal tract . It is an important regulator of the hormonal and nervous system and works by binding to G-protein-coupled receptors (GPCRs) on the surface of various cell types.

Somatostatin inhibits the secretion of pancreatic enzymes , gastrin and pepsin and lowers the blood flow in the splanchnic nerve area (supply area of ​​the visceral nerves major and minor splanchnic nerves ). It is therefore indicated for the treatment of severe acute gastroduodenal ulcer bleeding, bleeding in erosive or hemorrhagic gastritis, for adjuvant therapy to inhibit the secretion of heavily secreting postoperative fistulas of the pancreas and the upper small intestine, and for the prophylaxis of postoperative pancreatic complications after pancreatic surgery. It is also used for the therapy of secretory diarrhea. Somatostatin has a half-life of 1–3 minutes.

Biosynthesis and Isoforms

Two active forms (somatostatin-14 and somatostatin-28) are known, both of which form a cyclic structure through a disulfide bridge and are processed from a common precursor . The human SST gene encoding somatostatin is located in humans on chromosome 3 , gene locus 3q28.

regulation

Hormones and hormonal control circuits of the islet cells of the pancreas.

In the pancreas, somatostatin has a paracrine role like a tissue hormone , whereby it inhibits the release of glucagon and insulin from the neighboring α and β cells. It is also known to have an inhibitory effect on STH (somatotropic hormone), gastrin and cholecystokinin .

The release of somatostatin is a slow response to the formation of the second messenger cAMP . Over the course of hours , cAMP induces gene expression of this hormone through the following steps:

  • Activation of protein kinase A (PKA),
  • thereby phosphorylation of the CREB ( CRE binding protein ) on a serine residue ,
  • Binding of CREB modified in this way to a CRE recognition site ( cAMP response element ) on the promoter of the somatostatin gene,
  • Expression of this gene.

See also

literature

Individual evidence

  1. ↑ David Binas et al. a .: Perioperative management in patients with carcinoid syndrome / neuroendocrine neoplasia. In: Anästh Intensivmed Volume 61, 2020, pp. 16–24, here: p. 22 (“Somatostatin inhibits all other gastrointestinal hormones”).
  2. ^ SST somatostatin

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