Effect of intra-third ventricular administration of insulin on food intake after food deprivation.

It has been suggested that insulin may participate as a signal in the overall control of feeding. To further study this possible role of insulin, food-deprived male Wistar rats were subjected to intra-third cerebro-ventricular infusions of insulin. Infusion of 0.5 and 2.0 mIU/rat at 0745 hr, and 2.0 mIU/rat of insulin at 1900 hr in 24.5 hr food-deprived rats, and 2.0 mIU/rat of insulin at 2200 hr in 4 hr food-deprived rats did not significantly affect food intake. Infusion of the high dose of 8.0 mIU/rat of insulin at 2200 hr in 4 hr food-deprived rats significantly decreased food intake with a long-delayed and long-lasting effect. This and previous evidence suggest that intra-third ventricular administration of small amounts of insulin induce a decrease of food intake only in non-food-deprived rats.