The effects of duodenal peptides on glucagon-like peptide-1 secretion from the ileum. A duodeno--ileal loop?

Regul Pept. 2002 Dec 31;110(1):39-45. doi: 10.1016/s0167-0115(02)00157-x.

Abstract

Secretion of the gut hormone glucagon-like peptide-1 (GLP-1) is stimulated by meal ingestion. The response is rapid, suggesting a stimulatory pathway elicited from the upper gastrointestinal area. In pigs, we have been unable to demonstrate a neural stimulatory pathway, but GLP-1 secretion is regulated by local somatostatin secretion. In search for an endocrine pathway, we studied the effect of a range of concentrations of cholecystokinin octapeptide (26-33) (CCK 8), gastric inhibitory peptide 1-42 (GIP), secretin, motilin, calcitonin gene-related peptide (CGRP), and the modified amino acid, 5-hydroxytryptamine (serotonin, 5-HT) on GLP-1 and somatostatin release from isolated perfused segments of porcine ileum.GLP-1 secretion was stimulated by 1 nM CCK 8 and 10 nM GIP, but suppressed by 1 nM motilin and 1 microM 5-HT. Secretin and CGRP had no effect. Somatostatin secretion was stimulated by CCK 8 at 1 and 10 nM, by GIP at 1 and 10 nM and by 10 nM CGRP. Secretin, 5-HT and motilin had no effect on somatostatin secretion. We conclude that CCK 8 and GIP 1-42 stimulated GLP-1 secretion, but only in concentrations greatly exceeding normal postprandial concentrations. Thus, we find it unlikely that endocrine agents from the duodenum regulate GLP-1 secretion in pigs.

MeSH terms

  • Animals
  • Calcitonin Gene-Related Peptide / pharmacology
  • Chemotherapy, Cancer, Regional Perfusion
  • Duodenum / drug effects
  • Duodenum / metabolism*
  • Gastric Inhibitory Polypeptide / pharmacology
  • Gastrointestinal Hormones / pharmacology*
  • Glucagon / metabolism*
  • Glucagon-Like Peptide 1
  • Ileum / drug effects
  • Ileum / metabolism*
  • Motilin / pharmacology
  • Peptide Fragments / metabolism*
  • Postprandial Period / physiology
  • Protein Precursors / metabolism*
  • Sincalide / analogs & derivatives*
  • Sincalide / pharmacology
  • Swine

Substances

  • Gastrointestinal Hormones
  • Peptide Fragments
  • Protein Precursors
  • Motilin
  • Gastric Inhibitory Polypeptide
  • cholecystokinin (26-33)
  • Glucagon-Like Peptide 1
  • Glucagon
  • Calcitonin Gene-Related Peptide
  • Sincalide