Intracerebroventricular capsaicin influences the body weight increasing of rats

Adult rats were treated for ten days with capsaicin or with NaCl 0.9% directly injected into the lateral cerebral ventricles through a surgically implanted cannula. A third group of rats was implanted with the same cannula but did not receive any treatment. The food intake and the body weight were recorded for at least six weeks after stopping the treatment. The animals were always kept at constant ambient temperature of 22°C. The body weight of the capsaicin-treated group was reduced by the treatment, and showed a regular but lower degree of recovery trend than the control groups after the treatment period. In fact the capsaicin treated animals never reached the bodyweight of the controls.Nevertheless, food intake did not significantly vary after the capsaicin treatment. On the basis of these and previous findings,we can assume that capsaicin injected into the cerebral ventricles to rats kept at constant ambient temperature can acts on hypothalamic neurons, but a permanent action on metabolic pathways can not be excluded.