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

Somatostatin receptor types 1, 3, and 4 (SSTR1, SSTR3, SSTR4) are members of the G protein-coupled receptor (GPCR) family that mediate the inhibitory effects of the peptide hormone somatostatin (Source 1.1.2, 1.3.1). These receptors are widely distributed in the central nervous system and peripheral tissues, where they regulate hormone secretion, neurotransmission, and cell growth (Source 1.5.1). SSTR1 and SSTR4 are structurally similar and classified as the SRIF2 group, while SSTR3 is part of the SRIF1 group and is notably involved in inducing apoptosis (Source 1.1.3, 1.3.3). Clinically, these receptors are important in the management of neuroendocrine tumors and endocrine disorders such as acromegaly and Cushing's disease (Source 1.2.3, 1.3.1). Drugs like pasireotide are designed to target a broad range of SSTRs, including SSTR1 and SSTR3, to overcome resistance to more selective first-generation analogs (Source 1.2.1, 1.2.4). SSTR4 has gained attention as a novel therapeutic target for chronic pain and inflammation, with selective agonists showing potential for providing analgesia without the central side effects associated with opioids (Source 1.4.1, 1.4.4). The expression of these receptors serves as a critical biomarker for tumor diagnosis and the selection of patients for somatostatin-based therapies (Source 1.1.3, 1.3.2). However, targeting these receptors can lead to safety concerns such as hyperglycemia, primarily due to the inhibition of insulin release from pancreatic beta cells (Source 1.2.2, 1.2.3).

Other names

SSTR1SSTR3SSTR4Somatostatin receptor 1Somatostatin receptor 3Somatostatin receptor 4SST1SST3SST4Somatotropin release-inhibiting factor receptor 1/3/4

Agonism of SSTR1, SSTR3, and SSTR4 leads to the inhibition of adenylyl cyclase, resulting in decreased intracellular cyclic AMP (cAMP) levels, modulation of ion channels (e.g., activation of potassium channels and inhibition of calcium channels), and regulation of downstream signaling pathways such as MAPK and PTP, which collectively inhibit hormone secretion and cell proliferation.