Somatostatin receptor type 1, 3, and 4 (SSTR1/3/4)

Somatostatin receptor type 1 (SSTR1), type 3 (SSTR3), and type 4 (SSTR4) are members of the G protein-coupled receptor family that respond to the endogenous peptide somatostatin [UniProt P30872, P32745, P31391]. These receptors are widely distributed throughout the central nervous system, pancreas, and gastrointestinal tract, where they play critical roles in regulating physiological processes [PubMed PMID: 21153123]. SSTR1 and SSTR3 are primarily involved in the inhibition of hormone secretion, including growth hormone and insulin, and are often overexpressed in neuroendocrine tumors [StatPearls: Somatostatin]. SSTR3 is also uniquely linked to the induction of apoptosis and cell cycle arrest, making it a target for anti-tumor therapies [PubMed PMID: 15155836]. SSTR4 is distinct for its role in modulating inflammatory pain and neurogenic inflammation, offering a potential pathway for non-opioid analgesics [PubMed PMID: 23603431]. Pharmacologically, these receptors are targeted by somatostatin analogs; for instance, pasireotide is a multi-receptor ligand with high affinity for SSTR1 and SSTR3 used in treating Cushing's disease and acromegaly [FDA: Signifor Label]. Understanding the specific distribution and signaling of these subtypes is essential for developing selective therapies that minimize off-target effects while maximizing clinical efficacy in oncology and endocrinology [PubMed PMID: 28914573].

Other names

SSTR1SSTR3SSTR4SS1RSS3RSS4RSomatostatin receptor 1Somatostatin receptor 3Somatostatin receptor 4SRIF-2SRIF-3SRIF-4

Agonism of SSTR1, SSTR3, and SSTR4 triggers the activation of inhibitory G-proteins (Gi/o), which subsequently inhibits adenylyl cyclase activity and reduces intracellular cyclic AMP (cAMP) concentrations [PubChem]. This signaling cascade also involves the modulation of inward-rectifying potassium channels and the inhibition of voltage-gated calcium channels, leading to cellular hyperpolarization and the suppression of exocytosis, which effectively inhibits the secretion of hormones such as growth hormone, insulin, and glucagon [PubMed PMID: 21153123]. Additionally, SSTR3 activation is specifically associated with the induction of phosphotyrosine phosphatase (PTP) activity, which can lead to cell cycle arrest and apoptosis [PubMed PMID: 15155836].