HYPOTHALAMIC NPY AND PREPRO-NPY MESSENGER-RNA IN DJUNGARIAN HAMSTERS - EFFECTS OF FOOD-DEPRIVATION AND PHOTOPERIOD

Two catabolic states leading to loss of body weight were compared in t he Djungarian hamster (Phodopus sungorus campbelli). Hypothalamic neur opeptide Y (NPY) and gene expression for NPY and corticotropin-releasi ng factor (CRF) were examined after withdrawal of food for 48 h or exp osure to short photoperiod for 10 or 20 wk. Food deprivation was accom panied by increases in both NPY and prepro-NPY mRNA in the hypothalami c arcuate nucleus (ARC). Increases in gene expression were limited com pared with published data from the rat and were inversely related to p redeprivation body weight. Exposure to short photoperiod for 20 wk red uced body weight by 39%, but the activity of the NPY-ergic system was not affected; peptide concentration and gene expression were similar i n short photoperiod hamsters and long photoperiod controls. The hypoth alamic NPY-ergic system of the Djungarian hamster is sensitive to weig ht loss due to imposed manipulations of energy balance, but the catabo lism observed in short photoperiod gives rise to a body weight that is appropriate to the season encoded by the photoperiod. CRF gene expres sion was not affected by food deprivation or short photoperiod.