MAMMALIAN BOMBESIN-LIKE PEPTIDES EXTEND THE INTERMEAL INTERVAL IN FREELY FEEDING RATS

We evaluated the effects of systemic delivery of amphibian bombesin an d its mammalian homologues on the length of the postprandial intermeal interval. Adult male rats, feeding ad libitum, were injected intraper itoneally (i.p.) 5 min after the end of the first nocturnal meal with 0 (vehicle), 2.5, 5, or 10 nM/kg of tetradecapeptide bombesin (BN), ga strin-releasing peptide(1-27) (GRP(1-27)), the C-terminal decapeptide of GRP(1-27) (GRP(18-27)), the C-terminal decapeptide of neuromedin B (NMB23-32), or combinations of equimolar doses of GRP(1-27) and NMB23- 32. BN produced a potent, dose-related extension (maximum of 177%) of the first postprandial intermeal interval; GRP(1-27) produced a lesser but significant prolongation (maximum of 47%); the combination of GRP (1-27) and NMB23-32 produced an intermediate prolongation (maximum of 70%); GRP(18-27) alone and NMB23-32 alone failed to produce any signif icant change. Peptide effects were limited to the first postprandial i ntermeal interval. The results demonstrate that systemic, postprandial injection of BN, GRP(1-27), or the combination of GRP(1-27) and NMB23 -32 extends the duration of the postprandial intermeal interval. The r esults suggest that the endogenous peptides, released in the gastroint estinal tract by ingested food, have a potent satiety action, selectiv ely lengthening the inter-meal interval. (C) 1998 Elsevier Science Inc .