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 th e increase in daily food intake associated with chronic insulin treatm ent, insulin was continuously infused into either the vena cava (VC) o r the hepatic portal (HP) vein of 23 diabetic Lewis rats. Increasing i nsulin doses in both the VC (2 to 6 U/day) and HP (1.5 to 3.5 U/day) g roups 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 rat e 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.