Food intake after adrenaline and noradrenaline injections into the hypothalamic paraventricular nucleus in pigeons.

ABSTRACT

The effects of local injections of adrenaline (Adr, 6 nmol) or noradrenaline (Nor, 16 nmol) into the paraventricular nucleus (PVN) and into other anterior hypothalamic districts on feeding behavior were examined in satiated pigeons bearing a chronically implanted cannula. When infused into the PVN, both Adr and Nor reliably elicited feeding responses during the first hour after the injection. Feeding responses to Adr injections were significantly higher than those evoked by Nor. Other behavioral measurements (sleep, exploratory, and preening) were not affected by these treatments. Local pretreatment with phentolamine (20 nmol) but not with propranolol (20 nmol) abolished the feeding response induced by both Adr and Nor into the PVN. Lateral hypothalamic sites were also shown to respond to catecholamine injections with an increase in feeding, followed also by an increased sleep-like behavior duration. Together with other evidence, the present results indicate that adrenergically mediated circuits into the avian PVN play an important role in the mechanisms of food intake control, equivalent to that observed in mammalian species.