title: Colocalization of somatostatin receptor sst5 and insulin in rat pancreatic beta-cells.
abstract: Somatostatin, also known as somatotropin release-inhibiting factor (SRIF), is secreted by pancreatic delta-cells and inhibits the secretion of both insulin and glucagon. SRIF initiates its actions by binding to a family of six G protein-coupled receptors (sst1, -2A, -2B, -3, -4, and -5) encoded by five genes. Messenger RNA for both sst2 and sst5 have been reported in the rat pancreas, and the sst2A receptor protein has been localized to rat pancreatic alpha and pancreatic polypeptide-secreting cells in the islets as well as to pancreatic acinar cells. In this study we have used double immunostaining to show that the sst5 protein is expressed exclusively in the beta-cells of rat pancreatic islets and localizes with insulin-secreting alpha-cells. The sst5 receptor is not colocalized with sst2A. Thus, in the rat SRIF inhibits pancreatic insulin and glucagon secretion via different sst receptor subtypes.
authors.affiliation: Department of Endocrinology and Chemical Biology, Merck Research Laboratories, Merck & Co., Inc, Rahway, New Jersey 07065, USA. sudha_mitra@merck.com
authors.forename: S W
authors.initials: SW
authors.lastname: Mitra
authors.forename: E
authors.initials: E
authors.lastname: Mezey
authors.forename: B
authors.initials: B
authors.lastname: Hunyady
authors.forename: L
authors.initials: L
authors.lastname: Chamberlain
authors.forename: E
authors.initials: E
authors.lastname: Hayes
authors.forename: F
authors.initials: F
authors.lastname: Foor
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Schonbrunn
authors.forename: J M
authors.initials: JM
authors.lastname: Schaeffer
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000032:analysis* / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017481:Receptors, Somatostatin / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D007328:Insulin; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; D011994:Recombinant Proteins; C094573:somatostatin receptor 5