title: Ghrelin is present in pancreatic alpha-cells of humans and rats and stimulates insulin secretion.
abstract: Ghrelin, a novel growth hormone-releasing peptide isolated from human and rat stomach, is a 28-amino acid peptide with a posttranslational acylation modification that is indispensable for stimulating growth hormone secretion by increasing intracellular Ca(2+) concentration. It also functions in the regulation of feeding behavior, energy metabolism, and gastric acid secretion and motility. Using two different antibodies against the NH(2)- and COOH-terminal regions of ghrelin, we studied its localization in human and rat pancreas by immunohistochemistry. Ghrelin-immunoreactive cells were identified at the periphery of pancreatic islets in both species. Ghrelin co-localized exclusively with glucagon in rat islets, indicating that it is produced in alpha-cells. We identified ghrelin and des-acyl ghrelin in the rat pancreas using reverse-phase high-performance liquid chromatography combined with two radioimmunoassays. We also detected mRNA encoding ghrelin and its receptor in the rat pancreatic islets. Ghrelin increased the cytosolic free Ca(2+) concentration in beta-cells and stimulated insulin secretion when it was added to isolated rat pancreatic islets. These findings indicate that ghrelin may regulate islet function in an endocrine and/or paracrine manner.
authors.affiliation: Department of Internal Medicine, Miyazaki Medical College, Kiyotake, Miyazaki, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Date
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Nakazato
authors.forename: Suzuko
authors.initials: S
authors.lastname: Hashiguchi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Dezaki
authors.forename: Muhtashan S
authors.initials: MS
authors.lastname: Mondal
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoda
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kojima
authors.forename: Kenji
authors.initials: K
authors.lastname: Kangawa
authors.forename: Terukatsu
authors.initials: T
authors.lastname: Arima
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Matsuo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yada
authors.forename: Shigeru
authors.initials: S
authors.lastname: Matsukura
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D054439:Ghrelin; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D036361:Peptide Hormones; D010455:Peptides / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D010455:Peptides; D005947:Glucose; D002118:Calcium