Somatostatin receptor 2 and somatostatin receptor 5 (SSTR2 (for somatostatin receptor 2), SSTR5 (for somatostatin receptor 5))

The somatostatin receptors SSTR2 and SSTR5 are closely related G protein-coupled receptors (GPCRs) that mediate the inhibitory effects of the hormonal peptide somatostatin on various endocrine, neural, and tumor cell types. They function primarily by inhibiting hormone secretion (notably growth hormone, insulin, and others) through inhibitory G-protein signaling, regulating calcium and cAMP pathways. These receptors are major therapeutic targets in the treatment of neuroendocrine tumors, pituitary adenomas, and hormonal disorders such as acromegaly. Both SSTR2 and SSTR5 exhibit distinct but overlapping expression in tissues and tumors and serve as critical determinants of tissue responsiveness to somatostatin and its analogues. Drugs targeting these receptors include several synthetic peptide agonists (octreotide, lanreotide, pasireotide) designed for improved receptor selectivity and therapeutic efficacy in suppressing hormone excess and tumor cell growth. While both receptors are sometimes referred to in therapeutic or diagnostic contexts as "SSTR2/5", it is scientifically preferable to reference them separately for precise molecular, pharmacological, or clinical applications.

Other names

Somatostatin receptor type 2 (SSTR2)Somatostatin receptor type 5 (SSTR5)SSTR2A, SSTR2B (splice variants for SSTR2)SSTR-V (for SSTR5, less common)Somatostatin receptor subtype 2, subtype 5

Activation by peptide (or synthetic) agonist leads to Gi/o protein coupling, inhibition of adenylyl cyclase → reduced intracellular cAMP - Inhibition of voltage-gated calcium channels → reduced hormone/neurotransmitter release - Activation of phosphotyrosine phosphatases (cellular signaling modulation) - Promotion of apoptosis and inhibition of cell proliferation in some tumor contexts