The distribution of neuropeptide Y gene expression in the chicken brain

Neuropeptide Y (NPY) is demonstrated to play an important role in central control of voluntary feed intake (FI) of a variety of species. The commercial broiler chicken has been intensively selected over generations for increased body weight, achieved largely through increased FI. This has resulted in a contemporary animal that does not regulate FI to maintain energy balance, and represents a model for hyperphagia and obesity if allowed unrestricted access to feed. In the present study, the distribution of NPY mRNA was mapped in the brain of juvenile, broiler-strain chicken, and results interpreted in the context of previous data for strains that do not exhibit hyperphagia.NPY mRNA was widely distributed in the broiler brain, and highly expressed in the hippocampus, nucleus commissurae pallii, infundibular hypothalamic nucleus, nucleus pretectalis pars ventralis and neurons around the nucleus rotundus. Moderately labeled neurons were found in the lateral septal organ, nucleus periventricularis hypothalamus and nucleus paraventricularis magnocellularis. The pallium exhibited only sparse labeling.Generally, the distribution of cell groups expressing NPY mRNA was consistent with those regions exhibiting NPY immunoreactivity, and also matches the distribution of receptor binding sites reported in the literature for the chicken brain. This suggests that NPY may be involved in functions controlled by these regions. The observation of NPY gene expression in brain regions involved in appetite regulation is consistent with the recognized importance of NPY in FI regulation in a variety of species, and with the chronic hyperphagia, characteristic of the broiler.