Relationship of the middle hypothalamus to amygdalar hyperphagia

Abstract

Stereotaxic lesions in the lateral hypothalamus of the cat at the level of the tuberal region were found not to alter food intake or body weight from preoperative control levels whereas lesions restricted to the ventromedial nuclei produced hyperphagia and obesity. Cats with combined lateral and ventromedial lesions showed no changes in food intake or body weight. Cats with combined amygdalar, lateral and ventromedial lesions developed hyperphagia and obesity but the rates of weight gain were about three times faster than occurred with amygdalectomy alone. Food intake in this group after operation more than doubled preoperative levels and the gain in weight of the group during the dynamic phase of obesity amounted to 23.6% as compared to 2.3% for normal and sham-operated controls. It is concluded that the lateral hypothalamus does not function as a ‘feeding’ center in the cat but that the ventromedial nucleus is probably a ‘satiety’ center. Furthermore it is probable that inhibitory amygdalar effects on food intake do not operate through the middle hypothalamus since hyperphagia and obesity results following destruction of the entire middle hypothalamus and amygdalae.