Effect of voluntary wheel-running on insulin sensitivity and responsiveness in high-fat-fed rats

The effect of voluntary wheel-running on insulin resistance was studied in high-fat-fed rats. A sequential hyperinsulinemic euglycemic clamp procedure was employed (insulin infusion rates: 3 and 30 mU/kg BW/min) in 14 high-fa t-fed rats and 7 chow-fed rats under the awake condition. The high-fat-fed rats were further divided into a sedentary (n=7) and a voluntary wheel-runn ing (n=7) groups. Blood glucose was clamped at the fasting level in each ra t. Plasma insulin levels during the 3- and 30-mU/kg BW/min insulin infusion s were 40-50 and 450-550, muU/ml, respectively. At both 3 and 30 mU/kg BW/m in insulin infusions, high-fat-feeding showed a significant decrease in glu cose infusion rate (GIR), compared with the chow-fed rats. However, decreas ed GIRs were restored by the 4-wk wheel-running and reached similar levels as the chow-fed rats. Therefore, it could be concluded that voluntary wheel -running prevents insulin resistance induced by high-fat feeding.