Suppression of food intake induced by corticotropin-releasing factor family in neonatal chicks

Corticotropin-releasing factor (CRF), urocortin and urotensin I share amino acid sequences, and they inhibit food intake in mammals. CRF plays a poten t role in decreasing food intake in avian species, but the effects of uroco rtin and urotensin I have not been investigated. Therefore, the effect of t hese three peptides on food intake in the neonatal chick was compared. In E xperiment 1, birds were injected intracerebroventricularly (i.c.v.) with ei ther 0, 0.01, 0.1 or 1 mug of urocortin following a 3-h fast, and food inta ke was measured for 2 h post-injection. Food intake was suppressed in a dos e-dependent manner. Using a similar design in Experiment 2, the effect of u rotensin I was investigated. Urotensin I appeared to suppress food intake i n neonatal chicks more than urocortin did. In Experiment 3, the efficacy of CRF, urocortin and urotensin I was directly compared using one dose, 0.1 m ug. The results indicated that the suppressive effect on food intake was st rongest for CRF followed by urotensin 1, then urocortin. These results sugg est that the structure of receptors for the CRF family in chicks may be som ewhat different than in mammals. (C) 2001 Elsevier Science B.V. All rights reserved.