ONTOGENY OF NEUROPEPTIDE-Y EXPRESSION IN RESPONSE TO DEPRIVATION IN LEAN ZUCKER RAT PUPS

Hypothalamic neuropeptide Y (NPY) activity is believed to play an impo rtant role in the response to food deprivation in adult rats. Little i s known, however, about the role of the hypothalamic NPY system in the control of food intake in the preweanling rat. To address this issue, we examined the effect of deprivation on arcuate nucleus preproNPY ex pression in lean Zucker rat pups, using in situ hybridization. PreproN PY expression within the arcuate nucleus was localized to cells in the medial portion. Twenty-four hours of food, water, and maternal depriv ation significantly increased the relative abundance of preproNPY mRNA in pups on postnatal day (P)2, P9, P12, and P15 by 14-31%. This respo nse, however, was not observed on P5. The absence of an effect on P5 a nd the magnitude of the response at the other ages tested were not cor related with the amount of weight lost during deprivation.