Hypothalamic neuropeptide Y mRNA is increased after feed restriction in growing broilers

As part of an approach to uncover the brain mechanisms underlying the regul ation of energy balance in broiler chickens, we investigated the possible r ole of neuropeptide Y (NPY). The NPY gene expression was measured in the hy pothalamus of birds from a standard Ross male line and a Ross relaxed line. Both lines are derived from the same founder stock, but the relaxed line h as not been selected for rapid growth since 1976. Birds of each line consum ed feed either nd libitum or according to a standard commercial restricted feeding program. All groups of birds were killed at an average body weight of 2.4 kg. The NPY mRNA levels were significantly increased (P < 0.0001) in feed-restricted birds of both lines relative to ad libitum controls. No si gnificant differences were detected between the lines. These results show t hat NPY gene expression in the broiler hypothalamus is sensitive to changes in energetic status, as it is in mammals. However, the maintenance of sele ction pressure for high growth rate is not associated with altered hypothal amic NPY mRNA levels in the ad libitum or restricted state.