Ghrelin is present in pancreatic alpha-cells of humans and rats and stimulates insulin secretion.
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.
Date
Yukari
Y
Department of Internal Medicine, Miyazaki Medical College, Kiyotake, Miyazaki, Japan.
Nakazato
Masamitsu
M
Hashiguchi
Suzuko
S
Dezaki
Katsuya
K
Mondal
Muhtashan S
MS
Hosoda
Hiroshi
H
Kojima
Masayasu
M
Kangawa
Kenji
K
Arima
Terukatsu
T
Matsuo
Hisayuki
H
Yada
Toshihiko
T
Matsukura
Shigeru
S
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
D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D010455:Peptides; D005947:Glucose; D002118:Calcium