Cholecystokinin acts through catecholaminergic mechanisms in the hypothalamus to influence ingestive behaviour in the rat

Administration of cholecystokinin (CCK)(0.2-0.6 μg in a volume of 2 μl) into the lateral cerebral ventricle caused a decrease in intake of food but a relative increase in intake of water (or water-to-food ratio) in rats. To determine whether the anorexic actions of CCK were mediated through the hypothalamic nuclei, rats were infused with CCK (0.02-0.12 μg in a volume of 0.5 μl) through previously implanted hypothalamic cannulae. Administration of CCK into the lateral hypothalamus, but not the anterior hypothalamus or ventromedial hypothalamus, caused decreased intake of food and a relative increased intake of water. In addition, the responses induced by injection of CCK into the hypothalamus were completely abolished by selective depletion of catecholamines in the hypothalamus (eg. noradrenaline and dopamine) with intra-hypothalamic injection of 6-hydroxydopamine. Intraperitoneal administration of 0.12 μg of CCK had no effect on the intake of food and water in rats. The data indicate that CCK acts through catecholaminergic mechanisms in the hypothalamus to influence feeding behaviour.