Ghrelin, a new gastrointestinal endocrine peptide that stimulates insulin secretion: enteric distribution, ontogeny, influence of endocrine, and dietary manipulations.
Ghrelin, an endogenous ligand for the GH secretagogue receptor was characterized recently from extracts of rat stomach. We describe the enteric distribution of ghrelin, ontogeny of stomach ghrelin gene expression, effects of dietary and endocrine manipulations, and vagotomy on stomach ghrelin mRNA and peptide levels and secretion in the rat. Ghrelin expression was examined by Northern blotting. Tissue and plasma ghrelin levels were measured by RIA. A gradient of ghrelin production occurs in the rat gastrointestinal tract with the highest ghrelin expression and peptide levels in the mucosal layer of the stomach-fundus and the lowest levels in the colon. Ghrelin was not detectable in the fetal stomach and increased progressively after birth especially during the second and third postnatal weeks. Plasma ghrelin levels also increased in parallel with stomach ghrelin levels postnatally. Exogenous GH treatment decreased stomach ghrelin expression significantly. A high-fat diet decreased plasma ghrelin levels, whereas a low-protein diet increased plasma ghrelin levels significantly. Intravenous administration of ghrelin stimulates gastrin and insulin secretion. Our findings indicate that ghrelin is an important stomach hormone sensitive to nutritional intake; ghrelin may link enteric nutrition with secretion of GH, insulin, and gastrin.
Lee
Heung-Man
HM
Department of Surgery, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
Wang
Guiyun
G
Englander
Ella W
EW
Kojima
Masayasu
M
Greeley
George H
GH
D000821:Animal Feed; D000818:Animals; D004032:Diet; D004064:Digestive System / Q000378:metabolism*; D004702:Endocrine Glands / Q000502:physiology*; D005215:Fasting; D005753:Gastric Mucosa / Q000378:metabolism; D005755:Gastrins / Q000378:metabolism; D015870:Gene Expression; D054439:Ghrelin; D007275:Injections, Intravenous; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D036361:Peptide Hormones; D010455:Peptides / Q000097:blood / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014628:Vagotomy
D005755:Gastrins; D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D010455:Peptides; D012333:RNA, Messenger