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FDA Approved Growth Hormone Axis

Somatostatin

also known as: SRIF, Somatotropin release-inhibiting factor, SST, SST-14, SST-28, GHIH

The body's master 'off switch' for growth hormone and gut hormone secretion — the endogenous peptide behind octreotide, lanreotide, and pasireotide.

A cyclic 14- or 28-amino-acid peptide produced in the hypothalamus, pancreatic delta cells, and GI tract that broadly inhibits GH, TSH, insulin, glucagon, and gastrin release via five G-protein-coupled SSTR subtypes.

Mechanism of action

Binds five somatostatin receptor subtypes (SSTR1-5), all Gi/o-protein-coupled receptors. Activation inhibits adenylyl cyclase, reduces cAMP, opens K+ channels, and closes Ca2+ channels. Net effects: suppression of GH release from somatotrophs, inhibition of TSH, ACTH, insulin, glucagon, gastrin, secretin, VIP, and motilin. Also exerts antiproliferative effects via SSTR2/SSTR5 signaling, exploited in neuroendocrine tumor therapy.

Primary uses

  • Endogenous regulation of GH pulsatility (hypothalamic somatostatin tone)
  • Inhibition of pancreatic endocrine secretion (insulin, glucagon)
  • Suppression of GI hormones and gastric acid (paracrine role in gut)
  • Parent molecule for FDA-approved analogs used in acromegaly and carcinoid tumors

Typical dosing

N/A N/A N/A (endogenous)

Native somatostatin is not used therapeutically due to its ~2-minute half-life. Synthetic analogs (octreotide 100-500 mcg SC 2-3x daily; lanreotide 60-120 mg deep SC monthly) are used clinically instead.

Regulatory status

Native somatostatin is not marketed as a drug due to its ultra-short half-life, but its synthetic analogs octreotide (Sandostatin, approved 1988), lanreotide (Somatuline Depot, approved 2007), and pasireotide (Signifor, approved 2012) are FDA-approved for acromegaly, neuroendocrine tumors, and Cushing's disease respectively.

References

  1. [review] Patel YC. "Somatostatin and its receptor family." Front Neuroendocrinol. 1999;20(3):157-198.
  2. [review] Theodoropoulou M, Stalla GK. "Somatostatin receptors: from signaling to clinical practice." Front Neuroendocrinol. 2013;34(3):228-252.
  3. [pubmed] Brazeau P, et al. "Hypothalamic polypeptide that inhibits the secretion of immunoreactive pituitary growth hormone." Science. 1973;179(4068):77-79.

Related peptides

Octreotide

The first-generation somatostatin analog (FDA-approved as Sandostatin, 1988) — the pharmacological counterweight to growth-hormone excess. Used for acromegaly, carcinoid syndrome, and VIPoma; now available in injectable, LAR-depot, and oral (Mycapssa, 2020) formulations.

Lanreotide

The second-generation somatostatin analog (FDA-approved as Somatuline Depot, 2007 for acromegaly; 2014 for GEP-NETs; 2017 for carcinoid) — monthly deep-SC prefilled syringe. Functionally equivalent to octreotide LAR for most indications.

Pasireotide

The somatostatin analog for Cushing's disease — the only FDA-approved medical therapy targeting pituitary ACTH secretion, with uniquely broad somatostatin receptor affinity.

Somatropin (HGH)

FDA-approved recombinant human growth hormone — the direct hormone replacement, with multiple clinical indications, prescription-only status, and specific federal criminal provisions against off-label distribution.

Ghrelin

The 'hunger hormone' — the only known circulating appetite stimulant, and the endogenous ligand that GHRP-2, GHRP-6, and MK-677 were designed to mimic.

Sermorelin

The N-terminal 29 amino acids of native GHRH — a former FDA-approved diagnostic and pediatric GH-deficiency therapy, now widely compounded for adult anti-aging protocols.
Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.