Somatostatin receptor subtypes 1, 3, 4, and 5 (SSTR1, SSTR3, SSTR4, SSTR5) (SSTR1/3/4/5)

Somatostatin receptor subtypes 1, 3, 4, and 5 (SSTR1, SSTR3, SSTR4, SSTR5) are a group of G protein-coupled receptors that, along with SSTR2, mediate the inhibitory actions of the hormone somatostatin across various organ systems. These receptors are widely expressed in the pituitary gland, pancreas, gastrointestinal tract, and central nervous system, where they play critical roles in regulating the release of hormones such as growth hormone, insulin, glucagon, and ACTH. While SSTR2 is the primary target for conventional somatostatin analogs, the other subtypes have emerged as vital therapeutic targets for specific pathologies; for example, SSTR5 is highly expressed in corticotroph adenomas and is a key target for treating Cushing's disease. Additionally, SSTR4 is uniquely associated with mediating analgesic and anti-inflammatory effects without the typical endocrine side effects of other subtypes, making it a target for chronic pain research. Multi-receptor ligands like pasireotide, which target SSTR1, 2, 3, and 5, offer enhanced efficacy in resistant neuroendocrine disorders but are associated with a higher risk of hyperglycemia due to the potent inhibition of insulin secretion mediated by SSTR5.

Other names

Somatostatin receptor type 1Somatostatin receptor type 3Somatostatin receptor type 4Somatostatin receptor type 5SS1RSS3RSS4RSS5RSRIF-1SRIF-3SRIF-4SRIF-5

Agonism of these receptors leads to the activation of inhibitory G proteins (Gi/o), which inhibits adenylyl cyclase activity, reduces intracellular cyclic AMP (cAMP) levels, and modulates potassium and calcium ion channels to suppress cellular secretion and proliferation.