Galanin is a potent inhibitor of glucagon-like peptide-1 secretion from rat ileum.
The insulinotropic glucagon-like peptide 1 (GLP-1) originates from the lower intestines. Surprisingly, food ingestion induces a rapid increase of GLP-1 plasma levels. Therefore, a complex regulation for postprandial GLP-1 secretion must exist, which cannot be solely explained by direct contact of nutrients in the gut lumen with the GLP-1-releasing L cells. This was addressed in the present study utilizing an isolated vascularly perfused rat ileum preparation. Cholinergic (methacholine) as well as peptidergic stimulation by glucose-dependent insulin-releasing polypeptide (synonym: gastric inhibitory polypeptide) (GIP) strongly enhanced GLP-1 secretion from the rat ileum. The stimulation of GLP-1 secretion by methacholine was abolished by addition of atropine and partly reduced by galanin. Galanin dose-dependently antagonized the stimulatory effect of GIP on GLP-1 release. Atropine was without effect. Furthermore, employing double immunohistochemistry labeling techniques galanin-immunoreactive nerves were detected in the vicinity of GLP-1-immunostained cells. Our data indicate that stimulatory and inhibitory mediators regulate GLP-1 secretion and that galanin is a likely inhibitor.
Herrmann-Rinke
C
C
Department of Internal Medicine, Philipps University of Marburg, Germany.
Hörsch
D
D
McGregor
G P
GP
Göke
B
B
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D019004:Galanin / Q000032:analysis / Q000494:pharmacology*; D005934:Glucagon / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052216:Glucagon-Like Peptide 1; D007082:Ileum / Q000098:blood supply / Q000294:innervation; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000098:blood supply / Q000294:innervation / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D010446:Peptide Fragments / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011498:Protein Precursors / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D010446:Peptide Fragments; D011498:Protein Precursors; D016210:Methacholine Chloride; D001285:Atropine; D019004:Galanin; D052216:Glucagon-Like Peptide 1; D005934:Glucagon