Relationship between exercise-induced changes in serum and hepatic cholesterol metabolism in rats

The purpose of the present study was to determine the effects of exercise training on serum cholesterol level and hepatic cholesterol metabolism in rats. Twenty-four male Wistar strain rats, aged 6 weeks, were assigned to one of three experimental groups; control (n = 8), exercised 20 minutes a day (E20, n = 8), and exercised 60 minutes a day (E60, n = 8). Rats were sacrificed after ten weeks exercise. The levels of serum total cholesterol and HDL-cholesterol in the group E20 and group E60 were lower than that of control, 8% and 24% (p less than 0.01) for the total cholesterol and 10% and 24% (p less than 0.05) for the HDL-cholesterol, respectively. The activity of HMG-CoA reductase in liver microsome was significantly higher in the group E60 than that of control. The hepatic microsomal HMG-CoA reductase activity was negatively related to serum total (r = -0.62, p less than 0.01) and HDL (r = -0.58, p less than 0.01) cholesterol levels. From these results, we concluded that the enhancement of the cholesterol metabolism in the liver by exercise is a major course of the exercise-induced change in serum cholesterol of Wistar rats.