Alpha-helical crf_9-41, blocks stress- and crf- induced behavior changes in chicks

Three experiments were conducted to test the role of the brain corticotropin- releasing factor (CRF) system in mediating stress-induced behaviors and regulating food intake by using CRF receptor antagonists (a-helical CRF9_41 and astressin) in chicks. In Experiment 1, birds were intracerebro­ventricularly (i.c.v.) injected with 10 /ug of a-helical CRF_9-41 or saline and placed individually into an acrylic glass recording chamber 20 min post­injection and automatically monitored by an audio analysis application for 60 seconds. The number of distress vocalizations (DVs) induced by isolation was significantly suppressed by a-helical CRF_9-41 compared to the control group. Chicks were similarly treated with astressin in doses of 0, and 10 pg in Experiment 2, but no significant difference of DVs was observed. In Experiment 3, after a 3h fast, birds were i.c.v. injected with either saline, 0.1 µg of CRF, 0.1 µg of CRF + 5 µg of a-helical CRF_9-41 or 0.1 µg of CRF + 10 µg of a-helical CRF_9-41 and food intake was measured for 2h. CRF suppressed food intake and a-helical CRF_9-41 partially blocked such effect. The results suggested that 1) a-helical CRF_9-41 attenuated the behavior changes induced by isolation and exogenous CRF; 2) CRF receptors in avian species may be somewhat different from that in mammals.