Effects of lateral hypothalamic lesions on food intake of rats during exposure to cold

Lateral hypothalamic damage impaired both physiological and behavioral responses of rats during exposure to a 5 degree C environment. The brain-damaged animals usually did not conserve heat in the cold as well as control rats did, nor did they always increase their caloric intake to meet their energy needs. However, when given sucrose solution to drink instead of water, they did increase their ingestion of chow in response to cold exposure. It is likely that the elevated consumption of palatable fluid served to relieve dehydration and thereby removed its constraints on eating, thus permitting hyperphagia to occur. In contrast to these results, rats with large dopamine-depleting brain lesions, produced by intraventricular 6-hydroxydopamine treatments, always increased food intake when exposed to cold stress and demonstrated no apparent problems in peripheral vasoconstriction. Thus, it is unlikely that striatal dopamine depletions account for either the impaired feeding response or the inadequate heat conservation of rats with lateral hypothalamic lesions during cold stress.