Correlation between metabolic and behavioral effects of dexfenfluramine treatment

The consequences of dexfenfluramine (dFF) treatments on food intake (FI), locomotor activity (LA), respiratory quotient (RQ), and on changes in metabolic rate (MR) and in RQ that are induced by LA and FI, were investigated in 12 female Wistar rats fed ad libitum. Reduction of FI induced by dFF was correlated with an overall decrease in RQ that expresses increased lipogenesis. For a given amount of activity, MR and RQ changes were enhanced by dFF. On the other hand, dFF appeared to increase energy expenditure in relation to FI only to the extent that the energetic cost of LA itself was not taken into account. It is concluded that the anorexia induced by dFF may be due to the peripheral consequences of dFF treatments on the peripheral metabolism of glucides and lipids according to a lipostatic, glucostatic, or an ischymetric mechanism, and that the increase in energy expenditure previously reported after feeding, may reflect an increase in the energy produced in relation to LA rather than an increase in the thermic effect of feeding per se.