PROLONGATION OF THE POSTPRANDIAL INTERMEAL INTERVAL BY GASTRIN-RELEASING PEPTIDE(1-27) IN SPONTANEOUSLY FEEDING RATS

The present study explored the effects of intravenous gastrin-releasin g peptide(1-27) (GRP) on the postprandial intermeal interval (IMI) whe n delivered shortly after termination of the first spontaneous nocturn al meal in freely-feeding rats. Undisturbed, ad Lib-fed (milk), male r ats (n = 11) with chronic inferior vena caval catheters were infused w ith saline and each of three doses (2.5, 5 and 10 nmol/kg) of GRP in c ounterbalanced order. Infusions began 5 min after the last lick of the first nocturnal meal and continued for 2 min (60 mu l/min), with deli very of the peptide during the first minute. Infusions and recording o f meal data (licks) were fully automated and computer controlled. Both 5 and 10 nmol/kg of GRP significantly prolonged the IMI by over 50%, but had no effect on the size of the following meal. This is the first demonstration of the prolongation of the IMI by intravenous GRP in un disturbed, freely-feeding rats, and the result suggests that endogenou s GRP may play a role in the control of the postprandial intermeal int erval. (C) 1998 Elsevier Science Inc.