AMYGDALOID-LESION HYPERPHAGIA - IMPAIRED RESPONSE TO CALORIC CHALLENGES AND ALTERED MACRONUTRIENT SELECTION

Lesions of the most posterodorsal aspects of the amygdala in female ra ts result in hyperphagia and moderate obesity. In the present study, r ats with amygdaloid lesions did not increase their daily food intake w hen their powdered diet was diluted with 25 or 50% nonnutritive bulk. Control animals adjusted their food intake appropriately. In a second study, rats with lesions ate less food (lab chow pellets) than control s when allowed to eat for only 1 h/day for 10 days. In experiment 3, r ats were offered a three-choice macronutrient diet. Whereas four of si x control animals preferred the high-fat diet, all eight of the rats w ith amygdaloid lesions displayed a distinct preference for the high-ca rbohydrate diet, including those that had preferred the high-fat diet before surgery. These results, along with the previous finding that id entical lesions result in hyperinsulinemia, indicate that the amygdala is involved in both the homeostatic regulation of food (caloric) inta ke and the selection of macronutrients.