title: Ghrelin and the endocrine pancreas.
abstract: Ghrelin is a 28-amino-acid peptide predominantly produced by the stomach, while substantially lower amounts derive from other tissues including the pancreas. It is a natural ligand of the GH secretagogue (GHS) receptor (GHS-R1a) and strongly stimulates GH secretion, but acylation in serine 3 is needed for its activity. Ghrelin also possesses other endocrine and nonendocrine actions reflecting central and peripheral GHS-R distribution including the pancreas. The wide spectrum of ghrelin activities includes orexigenic effect, control of energy expenditure, and peripheral gastroenteropancreatic actions. Circulating ghrelin levels mostly reflect gastric secretion as indicated by evidence that they are reduced by 80% after gastrectomy and even after gastric by-pass surgery. Ghrelin secretion is increased in anorexia and cachexia but reduced in obesity, a notable exception being Prader-Willi syndrome. The negative association between ghrelin secretion and body weight is emphasized by evidence that weight increase and decrease reduces and augments circulating ghrelin levels in anorexia and obesity, respectively, and agrees with the clear negative association between ghrelin and insulin levels. In fact, ghrelin secretion is increased by fasting whereas it is decreased by glucose load as well as during euglycemic clamp but not after arginine or free fatty acid load in normal subjects; in physiological conditions, however, the most remarkable inhibitory input on ghrelin secretion is represented by somatostatin as well as by its natural analog cortistatin that concomitantly reduce beta-cell secretion. This evidence indicates that the endocrine pancreas plays a role in directly or indirectly modulating ghrelin secretion.
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, Ospedale Molinette, Corso Dogliotti 14, 10126 Turin, Italy.
authors: Fabio
authors: F
authors: Broglio
authors: Cristina
authors: C
authors: Gottero
authors: Andrea
authors: A
authors: Benso
authors: Flavia
authors: F
authors: Prodam
authors: Marco
authors: M
authors: Volante
authors: Silvia
authors: S
authors: Destefanis
authors: Carlotta
authors: C
authors: Gauna
authors: Giampiero
authors: G
authors: Muccioli
authors: Mauro
authors: M
authors: Papotti
authors: Aart Jan
authors: AJ
authors: van der Lely
authors: Ezio
authors: E
authors: Ghigo
mesh_terms: D000818:Animals; D004734:Energy Metabolism / Q000502:physiology; D054439:Ghrelin; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007515:Islets of Langerhans / Q000378:metabolism / Q000502:physiology*; D009490:Neurosecretory Systems / Q000502:physiology; D036361:Peptide Hormones / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones; D005947:Glucose