Age-Dependent Changes in the mRNA Levels of Neuropeptide Y, Proopiomelanocortin, and Corticotropin-Releasing Factor in the Hypothalamus in Growing Broiler Chicks

Lines of evidence suggest that hypothalamic neuropeptides have a physiological role in the regulation of food intake in mammals. However, little is known about the age-dependent change of hypothalamic neuropeptides in chicks. In this study, we investigated the age-dependent changes in hypothalamic mRNA levels of neuropeptide Y (NPY, an orexigenic neuropeptide), proopiomelanocortin (POMC, the precursor of anorexigenic neuropeptides), and corticotropin-releasing factor (CRF, a possible mediator in the POMC-induced anorexigenic pathway) in growing broiler chicks. The weights of body and abdominal adipose tissue of chicks were measured at 7, 14, 21, and 28 days of age, and the hypothalamic mRNA levels of NPY, POMC, and CRF were analyzed by real-time PCR. Hypothalamic NPY mRNA levels at 14 and 28 days of age were significantly (P<0.05) lower than that at 7 days of age. Hypothalamic POMC mRNA level at 28 days of age was significantly lower than that at 7 days of age. Hypothalamic CRF mRNA level was not affected throughout the experimental period. Abdominal adipose tissue weight was significantly increased after 14 days of age in chicks. Our findings demonstrated that the expressions of NPY and POMC are dependent on age in boiler chicken hypothalamus.