EFFECTS OF DIETARY PYRUVATE AND EXERCISE TRAINING ON INSULIN RESISTANCE IN ZUCKER RATS

Abstract

884 The effects of exercise training, pyruvate supplementation, and the combination of these two treatments were examined on total body and skeletal muscle insulin resistance in obese ( fa/fa) Zucker rats. Obese rats were randomly assigned to one of the following groups: control diet (Con), control diet/training (Con-Tr), pyruvate diet (Pyr), or pyruvate diet/training(Pyr-Tr). The pyruvate diet was the same as the control diet except Ca++-pyruvate was substituted for 6.3% of the dextrose. Exercise training was high-intensive interval training for 8 weeks. Total body insulin resistance and muscle insulin resistance were assessed by oral glucose tolerance and hindlimb perfusion, respectively. Plasma insulin responses during the OGTT were significantly lower in Con-Tr, Pyr, and Pyr-Tr rats than Con rats, whereas plasma glucose concentrations did not differ between the treatment groups. Insulin-stimulated hindlimb glucose uptake in Con-Tr, Pyr, Pyr-Tr rats (10.52±0.46, 9.86±0.89, and 10.63±0.44μmol/g/h, respectively) was significantly greater than in Con rats(6.64±0.34 μmol/g/h). Red quadriceps GLUT-4 protein was significantly greater in Con-Tr (61.5±3.0%) and Pyr-Tr(62.7±3.0%) rats than either Con (40.9±4.1%) or Pyr(38.7±3.5%) rats. These results indicate that exercise training and pyruvate supplementation attenuated the insulin resistance of the obese Zucker rat, by improving the effectiveness of insulin action on skeletal muscle, through distinct, yet related mechanisms.