Increased hypothalamic neuropeptide Y expression following food deprivation.

Neuropeptide Y potently stimulates food intake by acting within the hypothalamus. In this study we examined the possibility that hypothalamic neuropeptide Y expression is increased following food deprivation, as assessed by measuring the hypothalamic content of the mRNA coding for preproneuropeptide Y. Adult male Sprague-Dawley rats were allowed free access to water but were subjected to food withdrawal either overnight or for 72 h or not. Total RNA was isolated from whole hypothalamic dissections and the content of mRNA coding for preproneuropeptide Y was determined by RNase protection analysis. This study revealed a 2.6-fold increase in hypothalamic preproneuropeptide Y mRNA content in 72-h-food- deprived versus control rats with a small increase (40%), which did not reach statistical significance, in overnight-fasted versus control rats. In situ hybridization analysis was used to determine the cellular localization of this increased mRNA content. This study revealed an increase in hybridization in the arcuate nucleus of the hypothalamus of a magnitude similar to that observed using nuclease protection with no change observed over neocortex or reticular nucleus of the thalamus. These data are consistent with the hypothesis that expression of hypothalamic neuropeptide Y is modulated by peripheral metabolic status and support a role for neuropeptide Y in the control of food intake.