The effects of glucose or lipid infused intravenously or intragastrically on voluntary food intake in the rat

Glucose or lipid was infused intravenously (IV) or intragastrically (IG) 30 min before and also during the 17 h when rats were fed both a high-carbohydrate diet and a high-fat diet. Three-day infusions of 28.1 kcal of glucose reduced daily food intake by 19.7 +/- 1.9 kcal/day, representing an oral intake reduction equivalent to 70% of each calorie infused. Infusions of 28.1 kcal of lipid reduced baseline food intake by 11.2 +/- 2.7 kcal/day or 40% of each calorie infused (p < 0.0005). Furthermore, infusions of nutrient IG reduced baseline food intake by 17.6 +/- 2.1 kcal/day or 63% of each calorie infused, and infusions of nutrient TV reduced baseline food intake by 13.7 +/- 2.6 kcal/day or 49% of each calorie infused (p < 0.05). Also, glucose infusions (1.0 kcal/40 min) reduced 10-min food intake from saline baseline levels by 1.1 +/- 0.5 kcal, but lipid infusions had no effect. Infused glucose is more effective than lipid in inhibiting short-term intake, daily food intake, and intake of high-carbohydrate diet, and IG infusion is more effective than IV infusion in inhibiting daily food intake. (C) 1997 Elsevier Science Inc.