title: Impact of intestinal electrical stimulation on nutrient-induced GLP-1 secretion in vivo.
abstract: BACKGROUND
  Increases in L-cell release of GLP-1 are proposed to serve as a negative feedback signal for postprandial changes in gastric emptying and/or motility. Previous ex vivo data suggests that direct electrical stimulation (E-stim) of ileal segments stimulates secretion of GLP-1. This suggests potential feed-forward increases in GLP-1 driven by intestinal neuronal and/or motor activity.
  
  
  METHODS
  To determine if E-stim could increase GLP-1 levels in an in vivo setting, we administered E-stim and nutrients to male Long- Evans rats (300-350 g) under general anesthesia.
  
  
  RESULTS
  Nutrient infusion into the duodenum or ileum significantly increased plasma GLP-1 levels, but E-stim applied to these locations did not (P < 0.05). However, the combination of E-stim and nutrient infusion, in either the ileum or duodenum, significantly increased plasma GLP-1 when compared to nutrient infusion alone (P < 0.05), and this effect was not blocked by either norepinephrine or atropine. To test the impact of intestinal motor activity, the effect of extra-luminal mechanical stimulation (M-stim) on GLP-1 levels was assessed. In the duodenum, but not the ileum, M-stim plus nutrient infusion significantly increased GLP-1 over nutrient infusion or M-stim alone (P < 0.05).
  
  
  CONCLUSIONS
  Thus, both E- and M-stim of the duodenum, but only E-stim of the ileum augmented nutrient-stimulated GLP-1 release. These data demonstrate that factors beyond enteral nutrients could contribute to the regulation of GLP-1 secretion.
authors.affiliation: Division of Endocrinology and Metabolism, University of Cincinnati, Cincinnati, OH 45237, USA. darleen.sandoval@uc.edu
authors.forename: D
authors.initials: D
authors.lastname: Sandoval
authors.forename: A
authors.initials: A
authors.lastname: Dunki-Jacobs
authors.forename: J
authors.initials: J
authors.lastname: Sorrell
authors.forename: R J
authors.initials: RJ
authors.lastname: Seeley
authors.forename: D D
authors.initials: DD
authors.lastname: D'Alessio
mesh_terms: D000818:Animals; D004386:Duodenum / Q000378:metabolism*; D004558:Electric Stimulation / Q000379:methods; D005502:Food; D052216:Glucagon-Like Peptide 1 / Q000097:blood / Q000378:metabolism*; D007082:Ileum / Q000378:metabolism*; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D052216:Glucagon-Like Peptide 1
keywords: GLP-1; electrical stimulation