Feeding after nutrient infusions: Effects of hypothalamic lesions and vagotomy

Normal rats, and rats with lesions in the lateral hypothalamic area (LHA), ventromedial hypothalamus (VMH), or with subdiaphragmatic vagotomies were duodenally infused with nutrient solutions representative of all three macronutrients, and the effect on food intake for a period up to 3 hr was assessed. Glucose reduced consumption in the control and VMH controls, but not in the LHA or vagotomized groups. Amino acids decreased intake in the control and LHA groups and showed a trend toward a decrease in the VMH group, but not in the vagotomized group. Fat suppressed intake significantly in control, VMH and LHA groups and there was a trend toward suppression in vagotomized rats. The subcutaneous injection of insulin to the same animals elicited eating in all but LHA animals. These results suggest that different nutrients reduce food consumption in the short term through different anatomical substrates involving the peripheral and central nervous system.