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

Abstract

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.

Correlation analysis of hypothalamic mRNA levels of appetite regulatory neuropeptides and several metabolic parameters in 28‐day‐old layer chickens

“…Similar results were previously observed in broiler chickens (Saneyasu et al . ). Thus, age‐dependent changes in hypothalamic NPY mRNA levels were similar between broiler and layer chickens.…”

“…This result was not in agreement with the result in broiler chickens: hypothalamic POMC mRNA level at 28 days of age was significantly ( P < 0.05) lower than that at 7 days of age (Saneyasu et al . ). It is therefore likely that the age‐dependent change of hypothalamic POMC mRNA level differs between broiler and layer chickens.…”

“…We previously reported that the expressions of NPY and POMC are dependent on age in broiler chicken hypothalamus (Saneyasu et al . ). Therefore, in order to compare the results of the present layer study and our previous broiler study (Saneyasu et al .…”

“…Complementary DNAs of NPY, POMC and CRF were amplified with the primers as described previously (Saneyasu et al . ). As an internal standard, cDNA of ribosomal protein S17 was also amplified with the primers as previously described (Ibuki et al .…”

“…Therefore, in order to compare the results of the present layer study and our previous broiler study (Saneyasu et al . ), we used the same diet in these studies. This study was approved by the Institutional Animal Care and Use Committee (Permission number: 22‐05‐10) and carried out according to the Kobe University Animal Experimentation Regulation.…”