운동 강도 차이가 고지방식이 Sprague-Dawley Rat의 골격근 내 PGC-1α, PPAR-γ 및 인슐린 저항에 미치는 영향

Abstract

This study investigated the effects of exercise intensity on PGC-1α, PPAR-γ, and insulin resistance in skeletal muscle of high fat diet-fed Sprague-Dawley rats. Forty rats were randomly divided into five groups: sedentary control group (SED), high fat diet group (HF), high fat diet+low-intensity exercise group (HFLE, 22 m/min, 60 min, 6 days/week), high fat diet+moderate-intensity exercise group (HFME, 26 m/min, 51 min), and high fat diet+high-intensity exercise group (HFHE, 30 m/min, 46 min). After 4 weeks of high fat diet and endurance exercise training, the lipid profiles, insulin, and glucose concentrations were determined in plasma. PGC-1α, PPAR-γ, and GLUT-4 contents were measured in plantaris muscle. The rate of glucose transport in soleus muscle was determined under submaximal insulin concentration (1,000 μIU/mL insulin, 20 min) during muscle incubation. Plasma glucose during oral glucose tolerance test in HF was significantly greater than that in SED, and plasma glucose levels in the three exercise (EX) groups were significantly lower that those in SED and HF at 30 and 60 min, respectively (P<0.05). Plasma insulin levels in the EX groups were significantly reduced by 60 min compared to that in HF (P<0.05). The protein expression level of PGC-1α as well as muscle glucose uptake were significantly higher in SED and HF than those in the three EX groups (P<0.05), and HFHE showed significantly higher levels than HFLE and HFME. Expression levels of GLUT-4 and PPAR-γ were significantly higher in the HFLE, HFME, and HFHE groups compared to the SED and HF (P<0.05). Therefore, the results of this study indicate that 4 weeks of high fat diet significantly developed whole body insulin resistance but did not affect PGC-1α, PPAR-γ, or the glucose transport rate in skeletal muscle, and exercise training was able to attenuate deteriorated whole body insulin resistance due to high fat diet. In addition, high intensity training significantly affected PGC-1α expression and the glucose transport rate of skeletal muscle in comparison with low and middle training intensities.