Alpha-helical CRF_9–41, Blocks Stress- and CRF-induced Behavior Changes in Chicks

Abstract

Zhang, R., Ohgushi, A., Takagi, T., Nakanishi, T., Saito, E.-S., Yoshimatsu, T., Denbow, D.M. and Furuse, M. 2002. Alpha-helical CRF_9–41, blocks stress- and CRF-induced behavior changes in chicks. J. Appl. Anim. Res., 22: 169–176.

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 (α-helical CRF_9–41 and astressin) in chicks. In Experiment 1, birds were intracerebro-ventricularly (i.c.v.) injected with 10 fig of a-helical CRF_9–41 or saline and placed individually into an acrylic glass recording chamber 20 min post-injection and automatically monitored by an audio analysis application for 60 seconds. The number of distress vocalizations (DVs) induced by isolation was significantly suppressed by α-helical CRF_9–41 compared to the control group. Chicks were similarly treated with astressin in doses of 0, 5 and 10 fig 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 α-helical CRF_9–41 or 0.1 μg of CRF + 10 μg of α-helical CRF_9–41 and food intake was measured for 2h. CRF suppressed food intake and α-helical CRF_9–41 partially blocked such effect. The results suggested that 1) α-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.

Key words:

• Corticotropin-releasing factor (CRF)
• α-helical CRF_9–41
• astressin
• distress vocalizations (DVs)
• food intake
• chicks