EFFECT OF CENTRAL GLUCAGON-INFUSION ON MACRONUTRIENT SELECTION IN RATS

Compared were the light-dark pattern of absolute energy intake-and mac ronutrient selection of male Wistar rats intracerebroventricularly inf used with glucagon (5 ng/h) or saline for 7 days in a three-way select ion of macronutrients. Glucagon infusion induced a decrease in 24 h an d nocturnal energy intake, whereas no significant change in kcal intak e accompanied vehicle infusion. The decrease in kcal intake was due to a suppression of nocturnal ingestion of carbohydrate. This parameter was left unaffected with central vehicle infusion. Glucagon-infused ra ts had a significantly lower body weight gain than those infused with vehicle. Our study supports the hypothesis of central glucagon's suppr essive effect on food intake, but reveals that the latter reflects a l ower disposition to eat carbohydrate during the dark phase. The presen t work emphasizes the role of glucagon in the circadian regulation of carbohydrate intake.