HEPATIC PORTAL AND VENA-CAVA INSULIN INFUSIONS INCREASE FOOD-INTAKE IN DIABETIC RATS

To test whether the route of insulin delivery has a major effect on the increase in daily food intake associated with chronic insulin treatment, insulin was continuously infused into either the vena cava (VC) or the hepatic portal (HP) vein of 23 diabetic Lewis rats. Increasing insulin doses in both the VC (2 to 6 U/day) and HP (1.5 to 3.5 U/day) groups significantly increased daily food intake (p < .05). Intake was higher in the VC group at 3 U/day but not at 2U/day. When insulin was delivered at a low fixed dose, daily food intake of both the VC and HP groups only increased after urinary glucose losses increased. The rate of weight gain increased significantly in the VC varied group (p < .05). Insulin administration also increased energy expenditure (p < .01). These results suggest that the extent of the increase in daily food intake and body weight that occurs with peripheral exogenous insulin administration is dependent on the route of infusion.