Somatostatin (sst) Receptors
Somatostatin (somatotropin release inhibiting factor, SRIF) is an endogenous cyclic polypeptide with two biologically active forms. It is an abundant neuropeptide and has a wide range of physiological effects on neurotransmission, secretion and cell proliferation. The somatostatin receptor family consists of five subtypes, sst1-5, each differentially distributed throughout the central nervous system and periphery. Endogenous somatostatin receptor ligands include somatostatin-14 and somatostatin-28.
Somatostatin receptors have diverse biological functions due to their varied distribution and the fact that they couple to different second messengers - namely adenylyl cyclase, PLC, K+ channels and Ca2+ channels, amongst others.
Somatostatin receptors in the hypothalamus are involved in the regulation of growth hormone secretion. Other hormones regulated by somatostatin receptors include thyrotropin and prolactin. Somatostatin has antiproliferative effects via stimulation of protein tyrosine phosphatase activity and of the MAPK signaling cascade, with subsequent induction of G1 cell cycle arrest (sst1, sst4, sst5) and promotion of apoptosis (sst2, sst3). It also exhibits antiangiogenic activity via activation of sst3. Somatostatin regulates neuronal activity by regulating AMPA/kainate-mediated responses to glutamate. Different sst subtypes have opposing effects in this system.
Somatostatin receptors also play a role in blood glucose homeostasis; sst5 receptors in the pancreatic β-cells stimulate insulin secretion, whilst sst2 receptors are involved in glucagon secretion from α-cells. In addition, sst2 receptors inhibit gastric acid secretion and peristalsis in the jejunum. Somatostatin suppresses the release of numerous gastrointestinal hormones, including gastrin, cholecystokinin, secretin and VIP, and consequently plays an integral role in gastrointestinal endocrinology.View all products for Somatostatin (sst) Receptors »
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Literature for Somatostatin (sst) Receptors
Written by Janet Maguire and Anthony Davenport, this poster summarizes different GPCR classes of the vascular system and their cognate ligands. The predominant vasoactive response of blood vessels to specific receptor activation is also described. Endogenous ligands and Tocris compounds are listed.Request copy | View all posters
7-TM Receptor Signaling Poster
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