Somatostatin-14
Hormonal / InhibitoryAlso known as: SRIF-14, SST-14, Somatotropin Release-Inhibiting Factor, Growth Hormone Inhibiting Hormone, GHIH
Mechanism
Somatostatin-14 is the body's primary brake on growth hormone secretion. This 14-amino-acid cyclic peptide is produced in the hypothalamus, GI tract, and pancreas, where it broadly inhibits the release of numerous hormones including GH, TSH, insulin, glucagon, and gastric acid. It is the endogenous form that inspired drugs like octreotide and lanreotide.
Technical detail
Somatostatin-14 (SRIF-14) is an endogenous cyclic tetradecapeptide (Ala-Gly-Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys, disulfide bridge Cys3-Cys14) that binds all five somatostatin receptor subtypes (SSTR1-5), all Gi/Go-coupled GPCRs. Signaling includes inhibition of adenylyl cyclase (reducing cAMP), activation of K+ channels (hyperpolarization), inhibition of voltage-gated Ca2+ channels, and activation of protein phosphatases. In the anterior pituitary, it inhibits GH and TSH secretion. In the pancreas, it inhibits insulin and glucagon. In the GI tract, it suppresses gastric acid, gastrin, secretin, CCK, and VIP. Half-life is only 1-3 minutes due to rapid enzymatic degradation.
Evidence
- strong
Randomized controlled multicentre trial of somatostatin infusion after pancreaticoduodenectomy.
Gouillat et al. (2001) — The British Journal of Surgery — PMID: 11683740
In 75 post-pancreaticoduodenectomy patients, somatostatin-14 infusion reduced pancreatic juice leakage, clinical fistula incidence, stump-related complications, and hospital length of stay versus placebo.
- moderate
Dose-response effect of somatostatin-14 on human basal pancreatic hormones.
Annibale et al. (1987) — Pancreas — PMID: 2890157
In eight healthy volunteers, escalating somatostatin-14 infusions produced dose-related suppression of insulin, glucagon, and pancreatic polypeptide, showing that modest increases in circulating somatostatin can regulate basal pancreatic hormone release.
- moderate
Skamene et al. (1984) — Clinical Endocrinology — PMID: 6146413
Controlled somatostatin-14 infusions in healthy subjects showed a short plasma half-life (~2.7 minutes) and dose-dependent suppression of growth hormone, TSH, insulin, and glucagon secretion.