Effects of capsaicin on abdominal fat and serum free-fatty acids in exercise-trained rats

Abstract

This study was undertaken to determine whether capsaicin may influence abdominal fat deposition and circulating free-fatty acids in exercise-trained rats. In addition, the contribution of beta-adrenergic stimulation to capsaicin-induced changes in serum free-fatty acids was examined. All rats (n=144) were submitted to a treadmill exercise protocol for 14 days. During the first seven days, they were all fed ad libitum with a diet supplemented with capsaicin. Two thirds of rats maintained this diet during the last seven days (capsaicin-diet group) whereas the other rats were pair fed without capsaicin intake (control-diet group). At the end of the protocol, the acute effect of beta-adrenergic blockade (propranolol) on serum free fatty acid concentrations was tested in half of the capsaicin-diet group (propranolol-capsaicin-diet group). A placebo was injected to all other rats, i. e., the other half of rats in the capsaicin-diet group (placebo-capsaicin-diet group) and those in the control-diet group. Epididymal adipose tissue weight was significantly lower in the placebo-capsaicin-diet and propranorol-capsaicin-diet groups than in the control-diet group (p<0.0001). This change was accompanied by a higher level of fasting serum free fatty acids in the placebo-capsaicin-diet group. These results show that under conditions of pair feeding and exercise training, capsaicin intake induces a significant negative energy balance after only one week of treatment. This is associated with an increase in circulating free-fatty acids which is mediated by beta-adrenergic stimulation.