Effect of long-term exercise on gene expression of insulin signaling pathway intermediates in skeletal muscle

To elucidate the molecular mechanism underlying insulin sensitivity, we hav e thought to investigate gene expression of insulin signaling pathway inter mediates in skeletal muscle from sedentary and endurance-trained rats. Adul t male Sprague-Dawley rats were trained for 9 weeks on a treadmill; 30 m/mi n at a 6 degrees incline, 90 min/day, 5 days/week. The levels of PI 3-kinas e, GLUT4, p70 S6 kinase and Ras mRNA were significantly increased by 89, 40 , 38, and 47%, respectively, with running training; however, the Nck mRNA l evel was decreased by 24%. mRNA levels of SHP-2, Grb2, Sos, Shc, GAP, p62 a nd p90 S6 kinase were unaltered by running training. We have previously rep orted that endurance training increases mRNA levels of insulin receptor, IR S-1 and ERK1 in skeletal muscle of rats. Taken together, our data suggest t hat gene expression of the insulin signal pathway intermediates is modulate d by endurance training that may be associated with alteration of insulin s ensitivity. (C) 1999 Academic Press.