Interaction of corticotropin-releasing factor and glucagon-like peptide-1 on behaviors in chicks

Both corticortropin-releasing factor (CRF) and glucagon-like peptide-1 (GLP -1) inhibit food intake of chicks, but they also produce other behaviors. T he present experiments were undertaken to clarify the interaction of CRF an d GLP-1 regarding their anorectic actions as well as other behaviors. In Ex periment 1, birds were injected intracerebroventricularly (i.c.v.), followi ng a 3-h fast, with either saline, 0.1 mug of CRF, 0.1 mug of CRF + 0.1 mug of GLP-1 or 0.1 mug of CRF + 1 mug of GLP-1, and food intake was measured for 2 h. The injection of CRF decreased food intake, and CRF injected with GLP-1 suppressed food intake for up to 2 h. Birds were treated similarly in Experiment 2 in which the doses of CRF and GLP-1 were reversed. GLP-1 stro ngly suppressed food intake, and this effect was augmented by coadministrat ion of CRF. In Experiment 3, the behaviors of chicks injected with saline, CRF (0.1 mug), GLP-1 (0.1 mug) or CRF (0.1 mug) + GLP-1 (0.1 mug) were moni tored for the numbers of steps, vocalization and locomotion. Chicks were ex cited, moved more and vocalized loudly following injection of CRF, whereas an opposite response was seen with GLP-1. The behaviors were intermediate f ollowing the coinjection of the two peptides. In conclusion, CRF and GLP-1 interact in the chick brain, but the response depends on the behavior being measured. (C) 2001 Elsevier Science B.V. All rights reserved.