Effects of Treadmill Exercise on Muscle and Fat Growth Factor Expression in Obese Zucker Rats

Abstract

PURPOSE: The purpose of this study was to determine the effects of different intensity treadmill exercise programs over an 8 week period on the expression of UCP-2 in brown adipose tissue and TNF-α in soleus muscle in obese Zucker rats. METHODS: Zucker rats were divided into four groups (n=7 in each group): control, low intensity exercise (5-8m/min, 50-60%VO2max), moderate intensity exercise (14-16 m/min, 65-70%VO2max), and high intensity (22-25 m/min, 80%VO2 max) exercise groups. Rats in each exercise group were made to run on a motorized treadmill for 30 minutes per day, each day of the 8 week training period. Rats were sacrificed 24 hours after the last bout of exercise. Blood glucose was measured by Gluco-Card II. Brown adipose tissue was extracted and UCP-2 and TNF-α expression was analyzed using the Western Blotting technique. Data were analyzed by repeated measures ANOVA and Duncan's post hoc analyses. Statistical significance was set at p<0.05. RESULTS: UCP-2 protein expression of brown adipose tissue in the obese Zucker rats significantly increased following low and moderate intensity exercise training compared to the control group after 8 weeks. TNF-α protein expression in the soleus muscle was significantly decreased following the low and moderate intensity training programs compared to control group values after 8 weeks. Fasting glucose levels were not different between the groups after the exercise intervention. CONCLUSIONS: The present data suggests that low and moderate intensity treadmill exercise may improve glycometabolism control and fat oxidation by up-regulating UCP-2 expression, as well as minimizing skeletal muscle damage by the down-regulation TNF-α. Thus, low and moderate intensity exercise may be best for demonstrating anti-obesity and anti-inflammatory effects.