Autonomic and endocrine factors in the regulation of energy balance.

The regulation of energy reserves is modified by both the autonomic nervous system and the hormonal milieu. The activity of the two limbs of the autonomic nervous system shows a reciprocal response to stimulation or damage in either the ventromedial or the lateral hypothalamus. Ventromedial hypothalamic lesions decrease the activity of the sympathetic nervous system and increase the activity of the vagus nerve. Lateral hypothalamic lesions, on the other hand, increase the activity of the sympathetic nervous system. Central neurotransmitters involved in energy balance include the monoamines, amino acids, and peptides. Removal of adrenal steroids by adrenalectomy reverses or attenuates all forms of obesity by reducing food intake and possibly by increasing energy expenditure. Acute insulin injections increase food intake, but chronic injections may reduce it. A model showing the reciprocal relation of sympathetic activity to energy reserves is presented.