Aerobic exercise training as a mitigator of nonalcoholic fatty liver disease related fibrosis

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Nonalcoholic steatohepatitis (NASH) is a liver disease that is associated with obesity and is characterized by inflammation and fibrosis (scar tissue) within the liver. This condition is difficult to study in humans, therefore rodent models often are used to better understand factors that cause NASH. Additionally, it is unclear if aerobic exercise training can be used to treat the fibrosis that is associated with NASH. In the present study, lean and hyperphagic,obese rats were fed a diet high in fat, sugar and cholesterol to induce NASH. Hyperphagic, obese rats developed more fibrosis and inflammation within the liver than their lean counterparts, suggesting a more advanced disease state. When animals underwent exercise training or food restriction (~25% reduction in daily caloric intake)for 12 weeks, the obese rats had modest improvements in both liver fibrosis and inflammation. These improvements were associated with lowered hepatic stellate cell activation, a cell type in the liver that when activated begins to lay down scar tissue. Interestingly, the inactive, obese rat may actually have had the greatest capacity to turn over fibrotic tissue but this was not enough to overcome the diet-induced fibrosis. It is important to note that although both aerobic exercise training and modest food restriction improved liver health, these animals did not have a complete resolution of the liver disease.