Hypothalamic modulation of energy expenditure.

The acute effects of electrical stimulation of the hypothalamus on energy expenditure as measured by indirect calorimetry were investigated in 20 unanaesthetized rats. Thirty sec of stimulation increased both O2 consumption and respiratory quotient (R.Q.). The largest magnitude hypermetabolic response (39% mean peak increase in O2 consumption) was produced by stimulation of the ventromedial hypothalamic nucleus. Stimulation of the lateral hypothalamus produced hypermetabolic effects similar to but smaller than those produced by medial stimulation. A number of considerations suggest that the hypermetabolism is not secondary to changes in motor activity, carbohydrate utilization or blood glucose levels. Consequently, these data suggest that the hypothalamus modulates energy expenditure through changes in non-shivering thermogenesis. These metabolic changes may modulate the effects of various hypothalamic manipulations on body weight.