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

This study was undertaken to determine whether capsaicin may influence abdo minal fat deposition and circulating free-fatty acids in exercise-trained r ats. In addition, the contribution of beta-adrenergic stimulation to capsai cin-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 f irst 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 d ays (capsaicin-diet group) whereas the other rats were pair fed without cap saicin intake (control-diet group). At the end of the protocol, the acute e ffect of beta-adrenergic blockade (propranolol) on serum free fatty acid co ncentrations was tested in half of the capsaicin-diet group (propranolol-ca psaicin-diet group). A placebo was injected to all other rats, i. e., the o ther 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 propranolol-capsaici n-diet groups than in the control-diet group (p<0.0001). This change was ac companied by a higher level of fasting serum free fatty acids in the placeb o-capsaicin-diet group. These results show that under conditions of pair fe eding and exercise training, capsaicin intake induces a significant negativ e energy balance after only one week of treatment. This is associated with an increase in circulating free-fatty acids which is mediated by beta-adren ergic stimulation. (C) 2000 Elsevier Science Inc.