DISSOCIATION OF PARAVENTRICULAR NPY RELEASE AND PLASMA-CORTICOSTERONELEVELS IN RATS UNDER FOOD-DEPRIVATION

Extracellular neuropeptide Y (NPY) in the vicinity of the paraventricu lar nucleus (PVN) as well as NPY concentrations in the PVN were measur ed in rats under ad libitum feeding and 2-day and 10-day food deprivat ion. Plasma corticosterone levels were not changed by 2-day food depri vation but were increased by subsequent refeeding. In contrast, the ex tracellular NPY levels were increased by 2-day food deprivation and we re decreased rapidly by refeeding. The NPY concentrations were also in creased and increased further by refeeding. On the other hand, plasma corticosterone levels were elevated by 10-day food deprivation and wer e decreased by subsequent refeeding. The extracellular NPY levels were also increased by food deprivation and decreased gradually after refe eding. However, the postprandial levels were still elevated when plasm a corticosterone levels were returned to the basal levels. The NPY con centrations were also increased and increased further by refeeding. Th e amount of food intake after refeeding was positively correlated with the extracellular NPY levels. It is concluded that extracellular NPY levels in the PVN do not necessarily covariate with plasma corticoster one levels in rats under food deprivation.