PARELLEL METABOLIC AND FEEDING RESPONSES TO LATERAL HYPOTHALAMIC-STIMULATION

Energy metabolism and food intake affect each other. Many studies demonstrated that the lateral hypothalamus (LH) participates in the control of both feeding behavior and energy metabolism. We assessed the effect of a bipolar near threshold feeding eliciting electrical stimulation of the LH first on the feeding response and then on the background metabolism (metabolism free from the part due to locomotion) and respiratory quotient (RQ), on Wistar male rats, during either the light or the dark phase of the nycthemeron. LH stimulation resulted in a delayed and rather long increase in background metabolism that was more dramatic during the light phase. This metabolic response paralleled the delayed feeding response (more than 10 min) we obtained during behavioral tests. The increase in energy production was sustained by release of energy substrates from the endogenous stores, and this showed a circadian dependence. Mainly carbohydrates (rise in RQ) were used during the light phase stimulation whereas lipids (decrease in RQ) were released in the dark phase.