Somatostatin receptor (subtypes 1, 2, 3, and 5) (SSTR1/2/3/5)

Somatostatin receptors (SSTRs) are a group of five G protein-coupled receptors (SSTR1-5) that mediate the inhibitory actions of the peptide hormone somatostatin (Source: UniProt). Subtypes 1, 2, 3, and 5 are of particular clinical importance as they are frequently overexpressed in neuroendocrine tumors and pituitary adenomas (Source: PubMed, PMID: 21156721). These receptors function primarily by inhibiting adenylate cyclase and decreasing intracellular cAMP, which suppresses the secretion of various hormones including growth hormone, insulin, and glucagon (Source: StatPearls, NBK537256). In clinical practice, these receptors are targeted by somatostatin analogs (SSAs) to manage hypersecretory states and tumor growth. While first-generation SSAs like octreotide primarily target SSTR2, second-generation multi-receptor ligands like pasireotide exhibit high affinity for SSTR1, 2, 3, and 5, offering broader therapeutic potential for conditions like Cushing's disease (Source: FDA, Signifor Label). Additionally, the high expression of these receptors on tumor cells allows for their use in diagnostic imaging and peptide receptor radionuclide therapy (PRRT) (Source: NIH, NCI).

Other names

SRIF receptorsSS-RSomatotropin release-inhibiting factor receptorsSSTR1SSTR2SSTR3SSTR5

Agonism of these receptors activates inhibitory G proteins (Gi/o), which leads to the inhibition of adenylate cyclase, reduction of intracellular cyclic AMP (cAMP), and closure of voltage-gated calcium channels, ultimately suppressing the exocytosis of hormones and neurotransmitters (Source: StatPearls, NBK537256; UniProt).