Endurance training ameliorates insulin resistance via suppressing of muscle endoplasmic reticulum stress (884.8)

Abstract

It has been reported that ER stress caused by obesity triggers insulin resistance. In this study, we examined the effect of endurance training on ER stress in skeletal muscle caused by diet‐induced obesity (DIO). Male C57BL/6 mice were fed a control diet (10 kcal% fat) or a high‐fat (HF) diet (60 kcal% fat) for 12 weeks. At week 5 in the experiment, each dietary group of mice was subdivided into two groups (i.e. rest and training groups), and the training groups were loaded with endurance training using a treadmill (15 m/min, 30 min/day, 5 days/week). An oral glucose tolerance test (OGTT) was conducted at week 11 in the experiments. Plasma glucose concentration at 30 min of the OGTT and the area under the curve of the glucose concentration were higher in the rest group fed HF diet than in the rest group fed the control diet. The protein amount of Bip and phosphorylation levels of IRE1 alpha, JNK, and S307‐IRS‐1 were greater in the rest group fed HF diet than in that fed control diet. This impaired glucose tolerance caused by HF diet feeding was not observed in the trained group fed HF diet, and the plasma insulin concentration at 30 min of the OGTT was not different between rest and training groups fed HF diet. The increased ER stress signals were not observed in the training group fed HF diet. These results suggest that endurance training ameliorates insulin resistance caused by DIO via suppression of ER stress in the muscle.