Glucagonlike peptide-1 (GLP-1) participation in ileal brake induced by intraluminal peptones in rat

The aim of this study was to determine the mechanisms implicated in the gas trointestinal inhibition induced by ovoalbumin hydrolysate infused intralum inally. We studied the site of action, the possible implication of GLP-1, a nd the nervous mechanisms involved. We prepared anesthetized Sprague-Dawley rats with strain gauges in the antrum, duodenum, and proximal jejunum and a catheter in the duodenum or ileum for peptone infusion. Both intraduodena l (N = 6) and intraileal (N = 5) infusion of ovoalbumin hydrolysate induced inhibition of spontaneous motor activity in the antrum, duodenum, and prox imal jejunum. Duodenal inhibition induced by intraduodenal (N = 6) or intra ileal (N = 6) infusion of ovoalbumin hydrolysate was reversed by intraarter ial infusion of GLP-1 receptor antagonist, exendin (9-39) (3 x 10(-8) mol/k g/40 min). Finally, a combination of the adrenergic blockers phentolamine a nd propranolol (1 mg/kg, each; N = 7) completely blocked inhibitory gastroi ntestinal motor actions caused by intraduodenal infusion of ovoalbumin hydr olysate. This study demonstrates that peptone, intraluminally infused, part icipates in the regulation of gastrointestinal motility through stimulation of adrenergic pathways in anaesthetized rats. Moreover, these effects are partly mediated by GLP-1 secretion. The ileum seems to be the site of actio n, indicating a role of GLP-1 on the ileal break mechanism.