PARELLEL METABOLIC AND FEEDING RESPONSES TO LATERAL HYPOTHALAMIC-STIMULATION

Energy metabolism and food intake affect each other. Many studies demo nstrated that the lateral hypothalamus (LH) participates in the contro l of both feeding behavior and energy metabolism. We assessed the effe ct of a bipolar near threshold feeding eliciting electrical stimulatio n of the LH first on the feeding response and then on the background m etabolism (metabolism free from the part due to locomotion) and respir atory quotient (RQ), on Wistar male rats, during either the light or t he dark phase of the nycthemeron. LH stimulation resulted in a delayed and rather long increase in background metabolism that was more drama tic during the light phase. This metabolic response paralleled the del ayed 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 circad ian dependence. Mainly carbohydrates (rise in RQ) were used during the light phase stimulation whereas lipids (decrease in RQ) were released in the dark phase.