Abstract

Introduction: The purpose of this study was evaluating the effect of obesity and weight reduction induced by endurance training on UCP3 mRNA expression in C57BL/6 mice. Materials and Methods: Twenty-four C57BL/6 mice consumed a high-fat diet, while 6 (NB Group) were fed a normal chow for 12 weeks. After the fattening period, 6 obese mice (OB Group) were sacrificed. Twelve mice trained 5 sessions per week for 12 weeks on a rodent treadmill with high (HI Group) (~75% VO2max) and/or low intensity (LI Group) (~50% VO2max) during a training period. The control group (OC Group) was kept inactive in the cages till the end of the period. Body weight was measured and recorded weekly. UCP3 mRNA expression was measured in gastrocnemius muscle using Real Time-PCR method and plasma FFA concentrations were measured using the ELISA method. Results: In the training groups, weight reduction was significant in the 8th week (p<0.05). Average relative UCP3 mRNA expression was significantly lower in the HI and LI groups, than in the OC group (0.5±0.25 and 1.04±0.96, respectively, vs. 2.58±0.57 arbitrary unit p<0.05). Plasma FFA conce­ntrations were significantly lower in the HI and OB groups compared to the LI group (p<0.05). Conclusion: When energy intake and consequently body weight increases, UCP3 increases to extend the thermogenesis and fatty acid oxidation’s process. In contrast, UCP3 downregulates with exercise-induced weight loss in order to counteract this process.