High-fat diet affects plasma membrane GLUT4 content in skeletal muscle from Sprague-Dawley rats

AIM: To explore the change of the amount of GLUT4 protein at the plasma membrane of the rat skeletal muscle after high-fat feeding. METHODS: The animals were divided into three groups (ten for each): group I: control; group II: high-fat feeding; group III: high-fat feeding + dietary treatment. The rat model of insulin resistance (IR) was made by feeding high-fat diet for eight weeks. And then insulin-resistant rats were fed with chow diet for 4 weeks. Fasting plasma glucose and fasting serum insulin levels were measured before and after dietary treatment, respectively. Insulin treatment was achieved by intraperitoneal injection of insulin (10 unit insulin per kg body weight) 15 minutes before killing the animals. The right hindlimb skeletal muscle was rapidly dissected. Then the expression of GLUT4 protein at the plasma membrane in all the animals was assessed with Western bloting. RESULTS: The GLUT4 content at the plasma membrane in high-fat-fed rat skeletal muscle was significantly lower (about 31%) than that in controls (P<0.01). Dietary treatment partly corrected fasting blood glucose from(6.20±0.39)mmol/L to(5.78±0.74)mmol/L]and fasting serum insulin levels from(17.19±1.93)mU/L to(11.68±1.28)mU/L] and increased the GLUT4 content at the plasma membrane by 1.14-fold in insulin-resistant rat skeletal muscle. CONCLUSION: High-fat feeding induces IR in Sprague-Dawley rats. The mechanism may be involved in decreased cell-surface level of GLUT4 through affecting intracellular insulin signaling and then decreasing GLUT4 trafficking.