Reciprocal relation between the sympathetic nervous system and food intake.

The present studies have examined the hypothesis that food intake and sympathetic activity are inversely related. Following lateral hypothalamic lesions, food intake decreases and sympathetic activity rises. When pair-gained animals are used, the sympathetic activity of the LH-lesioned animals is above that of ad lib fed controls, and the sympathetic activity of the pair-gained animals is below that of the controls. With VMH-lesions, food intake rises and sympathetic activity falls. Several drugs, including 2-deoxy-D-glucose, fenfluramine, corticotropin releasing hormone, and neuropeptide Y, all show this reciprocal relationship. Three exceptions to this rule, the rat with a PVN lesion, cold exposure and animals eating a highly palatable diet, are discussed. Under the usual circumstances, the sympathetic activity appears to play a tonic role in regulating the onset of a meal, and the acute changes in sympathetic activity after eating may play a role in the onset of satiety.