Somatostatin receptor (subtypes 1–5; preferred: "Somatostatin receptor 2" in clinical contexts when a single receptor is meant) (SSTR or SSTR1, SSTR2, SSTR3, SSTR4, SSTR5)

Somatostatin receptors are a family of five G protein-coupled receptors (SSTR1–SSTR5) mediating the biological actions of the peptide hormone somatostatin. These receptors are widely distributed in endocrine glands, the central nervous system, and many other tissues. All subtypes share a seven-transmembrane domain architecture and transmit intracellular signals primarily via inhibitory G proteins. Somatostatin receptors function in the inhibition of hormone secretion, modulation of neurotransmitter release, and regulation of cell proliferation and angiogenesis. Their clinical relevance is significant, especially in neuroendocrine tumors, where they serve both as diagnostic imaging targets and as points of therapeutic intervention for somatostatin analogues and peptide receptor radiotherapy (PRRT). SSTR2 is the most therapeutically exploited subtype and a frequent biomarker of tumor responsiveness. Clinical use is often challenged by resistance development and potential systemic hormonal side effects.

Other names

SST receptorSSTR (refers collectively or individually to SSTR1–SSTR5)SRIF receptorsomatostatin receptor subtype 1/2/3/4/5

Agonist-induced activation of SSTRs inhibits adenylyl cyclase, reducing cAMP Inhibition of hormone secretion (GH, insulin, glucagon, etc.) Blockade of mitogenic signaling, causing growth arrest Induction of apoptosis in tumor cells Inhibition of angiogenesis Diagnostic imaging via radiolabeled ligand binding