Growing evidence suggests that insulin interacts with both orexigenic and anorexigenic peptides in the brain for the control of feeding behavior in mammals. However, the action of central insulin in chicks has not yet been identified. In the present study, we investigated the effects of central injection of insulin on feeding behavior in chicks. Intracerebroventricular (ICV) administration of insulin, at doses that do not influence peripheral glucose levels, significantly inhibited food intake in chicks. Central injection of insulin in chicks significantly increased expression of pro-opiomelanocortin (POMC) mRNA, and decreased that of neuropeptide Y (NPY) mRNA. Finally, co-injection of the melanocortin antagonist (SHU9119 or HS014) prevented the reduction in food intake caused by ICV administration of insulin. These data suggest that insulin functions in chicks as an appetite-suppressive peptide in the central nervous system, and that the central melanocortin system mediates this anorexic effect of insulin, as in mammals.

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It is important to quantify and estimate stressful stimulation because stress appears to limit productivity and welfare in poultry. The purpose of this study is to investigate the e ect of acute isolation stress ( , or min) on the levels of blood parameters (glucose, free fatty acid (FFA) and corticosterone (CORT)) and diencephalic stress related peptide gene expressions (corticotrophin-releasing hormone (CRH) and arginine vasotocin (AVT)) in neonatal chicks. Although the isolation treatment did not a ect concentration of plasma glucose ( . ), plasma FFA at min after treatment was higher than control ( . ). The level of CORT increased significantly after and min of treatment ( . ), but that significant increase had disappeared in the chicks isolated for min. The expression level of CRH in the chicks treated for min, but not in the chicks treated for and min, was higher than in control ( . ), whereas there was no change in AVT mRNA for any of the isolation treatments ( . ). These findings demonstrate that high levels of CORT, through negative feedback, decrease CRH synthesis until min after isolation, and further suggest that AVT expression in the diencephalons may not be applicable as an indicator of acute isolation stress in neonatal chicks.: AVT, Chick, Corticosterone, CRH, Isolation stress as a measure of endocrine response to stress in the HPA axis (Selye, ; Natelson ; Charmandari In recent years, stress in livestock has been the greatest ). Also, the activation of the HPA axis under concern of animal scientists and producers because it not stressful conditions is accompanied by the SAM axis, as only reduces productivity and increases morbidity but it suggested by the increase in plasma catecholamines also a ects to animal welfare. Thus, it is important to (Gisolfi ; Kregel ). Activation of quantify and estimate various stress conditions in animals.both HPA and SAM axis, thereafter, induce glucocorThe physiological stress pathways are channeled along two ticoid-and -adrenoceptor-mediated lipolysis (Bjorntorp, main routes: the hypothalamic-pituitary-adrenal (HPA) ; Bowers ), respectively, which results in axis and the sympathetic-adrenal-medullary (SAM) axis increase in plasma free fatty acid (FFA). FFA is, there-(e.g., Gregory, ). In stress response, the HPA axis is fore, used as a measure of neural stress response both in the primary neuroendocrine system activated. The HPA the HPA and SAM axis. axis has been studied extensively and corticotrophinAlthough these parameters in stress response di er acreleasing hormone (CRH) and arginine vasotocin (AVT) cording to the intensity or kind of stressor and in the time both stimulate the release of adrenocorticotropic hormone course, the details of endocrine response to stressors in (ACTH) and glucocorticoids in an attempt to maintain chickens, especially in the neonatal period system, remain homeostasis (Sapolsky ). Plasma cortisol or to be fully explored. To quantify and estimate various corticosterone (CORT) is the primary glucocorticoid used stress conditions in...

The objective of the present study was to evaluate the temperament of a native Japanese chicken breed (TosaJidori) using the tonic immobility test for the detection of fearfulness. Each chick (2, 5, 10 or 15-day old) was placed on its back on a table and restrained by hand. Thereafter, if the chick lay still, it was then released and observed. The number of inductions and tonic immobility duration was recorded. The duration in the male was shorter than that in the female at 2-day old, whereas higher than that in the female at 15-day old. The duration of tonic immobility was affected by age in the male (P＜0.05). There was a positive correlation between them in the male, and a negative correlation in the female. As for the number of induction, no significant differences and tendencies were found between sex and age. These findings demonstrate that Tosa-Jidori chicks show sexual differences in the fear response and further suggest that the temperamental differences may correspond to genetic characteristics of breeds.