title: GLP-1 secretion in response to oral and luminal palatinose (isomaltulose) in rats.
abstract: Palatinose (isomaltulose), a slowly digested disaccharide, is used as a non-cariogenic sugar and as a sucrose substitute in several foods. Because of its ability to lower postprandial glycemia, palatinose may be beneficial as a treatment for impaired glucose metabolism. Glucagon-like peptide-1 (GLP-1) improves glycemia via enhancing pancreatic beta-cell functions. The secretion of GLP-1 is stimulated by sugars, including glucose and artificial sweeteners. In this study, we examined whether palatinose induced GLP-1 secretion in vivo and in vitro. Firstly, portal GLP-1 and glucose were measured after oral administration of palatinose or sucrose in conscious rats. Secondly, portal GLP-1 and glucose were measured after jejunal or ileal administration of each sugar in anesthetized rats. Finally, GLUTag, a murine GLP-1-producing cell line, was exposed to several sugars, including palatinose and sucrose, to observe the direct effect of these sugars on GLP-1 secretion. Compared with sucrose, palatinose enhanced portal GLP-1 level when administered orally in conscious rats. Both palatinose and sucrose induced a significant increase in portal GLP-1 after jejunal or ileal administration of each sugar in anesthetized rats. Ileal administration triggered a greater response than did jejunal administration. Glycemic responses were higher in sucrose-treated rats than in palatinose-treated rats in every experiment. In GLUTag cells, glucose induced a significant increase in GLP-1 secretion, but neither sucrose nor palatinose had an effect. These data demonstrate that luminal palatinose induces GLP-1 secretion in rats. However, it is likely that GLP-1 secretion is triggered mainly by glucose released in the lumen rather than by palatinose itself.
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo, Japan. hira@chem.agr.hokudai.ac.jp
authors.forename: Tohru
authors.initials: T
authors.lastname: Hira
authors.forename: Maya
authors.initials: M
authors.lastname: Muramatsu
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okuno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hara
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002460:Cell Line; D019858:Enteroendocrine Cells / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000097:blood / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D007534:Isomaltose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010634:Phenobarbital / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000008:administration & dosage / Q000378:metabolism; D013549:Sweetening Agents / Q000008:administration & dosage* / Q000378:metabolism
chemical_list: D013549:Sweetening Agents; D013395:Sucrose; D007534:Isomaltose; D052216:Glucagon-Like Peptide 1; D005947:Glucose; C008189:isomaltulose; D010634:Phenobarbital