Differential feed intake responses to central corticotrophin releasing factor in lines of chickens divergently selected for low or high body weight

Effects of intracerebroventricular (ICV) injection of corticotrophin releasing factor (CRF) on feed intake were evaluated in two lines of White Plymouth Rock chickens that have been selected from a common base population for high (HWS) or low (LWS) juvenile body weight. Both lines responded with reduced feed intake after ICV CRF; however, the threshold of response was lower in line LWS than HWS. Additionally, the effects of two receptor antagonists, astressin and α-helical CRF (9–41; α-CRF), and the effect of CRF fragment 6–33, (which displaces CRF from its binding protein), were evaluated in these lines. Although all three antagonists increased feed intake in line LWS but not line HWS, they attenuated the appetite-reducing effects of CRF only in line HWS. Peripheral plasma corticosterone concentrations after an acute stressor were higher in line LWS than in line HWS. These data support the thesis of correlated responses in the CRF system to selection for high or low juvenile body weight. These differences may contribute to differential feed intake, and hence altered body weights.