Effects of Physical Exercise in the Ampkα Expression and Activity in High-fat Diet Induced Obese Rats

Introduction: High-fat diet is a special risk factor in the development of insulin resistance and type 2 diabetes. Objective: To investigate the effects of physical exercise on the AMPK expression and activity in high-fat diet induced obese rats. Methods: Wistar rats were randomly divided into four groups and received either a rat maintenance diet (control group) or an isocaloric high-fat diet (HFD) (sedentary groups and exercised groups) for four months. Two different exercise protocols were utilized: acute or chronic swimming exercise. Insulin tolerance test was performed to estimate whole-body insulin sensitivity. AMPK alpha and GLUT4 as well as pAMPK alpha and pACC of rats' skeletal muscle levels were determined using Western blot. Results: Insulin tolerance test revealed a significantly impaired insulin action after HFDt feeding, indicating high-fat induced insulin resistance when compared to control group. Four months of HFD treatment induced to significant decrease of AMPKa (2.2-fold) and GLUT4 (2.5-fold) protein contents and also of p-AMPK alpha (2.4-fold) and p-ACC (2.5-fold) in sedentary rats' skeletal muscle when compared with the control group. Both exercise protocols resulted in increase of AMPKa and ACC phosphorylation and increase in insulin sensitivity, while chronic physical exercise alone provoked increase in these proteins expression (p < 0.05). Conclusion: High-fat feeding impairs AMPKa activity, while AMPKa activation by physical exercise improves insulin resistance, thus indicating that obese rats normally have the AMPK pathway preserved.