Examination of difference in central nervous system between chickens selected for meat and egg production

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The aim of this project is to clarify the difference in the central nervous system related to homeostasis, feeding behavior, responses to stress and osmotic regulation, between chickens selected for meat and egg production.Neuropeptide Y (NPY) peptide content in the hypothalamus during embryonic and early post-hatched period was larger in the egg-type than in the meat-type chickens, which is inconsistent with orexigenic exogenous NPY. Compared to egg-type chickens, higher abundance proopiomelanocortin mRNA in the hypothalamus and larger anorexigenic effect of intracerebroventricularly injected beta-MSH in the meta-type chickens are likely to be responsible for their ability to eat more feed. In addition to this, the turnover rate of serotonin and dopamine in the hypothalamus might be also associated with the different feeding behavior between both types of chickens.Less locomotion activity and vocalization number induced by isolation of chickens was involved in the lower melatonin prod … More uction in the pineal, lobe, brain stem in the meat-type chickens. Heat production during embryonic period was less and lipid metabolism in the meat-type chickens was more active than those in the egg-type chickens, which may be one of factors to make the former grow faster. Nagoya chickens being selected for meat- and egg-types were useful animals to show that the embryonic heat production and responses to stressor are items for selection.Arginine vasotocin gene expression in the hypothalamus responding to hypertonic saline injection was likely to be mediated through hypothalamic not only TonEBP but any other pathway than TonEBP.Distribution of cells and fibers immunoreactive to galanin and NPY in the hypothalamus was similar between both the types of chickens. NPY neuron in the hypothalamus was suggested to project to the parvocellular neuron of the paraventriclular nucleus in both types of chickens.Collectively, there is little differences in the structure of the neuron containing regulatory peptide between the two types of chickens, but some differences in the expression of peptide genes and in neurotransmitters metabolism have been shown to contribute to the phenotype of chickens. Less