Effect of peptide YY on insulin release stimulated by 2-deoxyglucose and neuropeptides in dogs

Peptide YY (PYY) is a hormone released from gut after a meal. The objective of this study was to determine the effect of PYY on insulin release stimulated by either 2-deoxyglucose (2-DG) or neuropeptides in conscious dogs with gastric and duodenal fistulas. In control experiments dogs received either 2-DG (75 mg/kg i.v. bolus) or atropine (25 micrograms/kg bolus followed by 20 micrograms/kg/h i.v.) plus 2-DG (75 mg/kg i.v.) or bethanechol (80 micrograms/kg/h i.v.) or vasoactive intestinal peptide (VIP, 4 micrograms/kg i.v. bolus) or gastrin-releasing peptide (GRP, 400 pmol/kg/h i.v.) or tetragastrin (G4, 100 micrograms/dog, i.v. bolus). On separate days, PYY was also infused intravenously in combination with one of the above stimulants. Given intravenously, PYY (200, 400 pmol/kg/h) significantly inhibited 2-DG stimulated-insulin secretion in a dose-dependent fashion. This inhibitory effect also existed in the presence of atropine. Peptide YY (400 pmol/kg/h) depressed the insulin levels in response to GRP or G4 but failed to inhibit bethanechol- and VIP-stimulated insulin release. After administration of the above stimulants, PYY did not modify the blood sugar concentrations. These results demonstrated that PYY might inhibit the cephalic phase of insulin release from dogs triggered by 2-DG and by the neuropeptides GRP and G4. Thus, PYY may play a negative feedback regulatory role on insulin release.