Obesity is a primary cause of hepatic lipid accumulation, leading to nonalcoholic fatty liver disease (NAFLD). As there are no FDA-approved therapies for NAFLD treatment, weight loss through lifestyle intervention is the first-line therapy. Exercise improves hepatic function in patients with obesity related NAFLD. However, the mechanisms whereby exercise mediates the enhancement of liver function are largely unknown. This study evaluated the impact of exercise training on NAFLD in mice with obesity. At 8 weeks of age, mice were randomized to low-fat (LFD) or high-fat diet (HFD). After 4 weeks of dietary intervention, mice were randomized to either control (SED) or exercise training (ExT) with experimental diet for 10 weeks. ExT mice completed 45 minutes of moderate-intensity treadmill running 4 days/week. Body weight was measured weekly, and body composition and maximal treadmill running were evaluated at weeks 0, 4, and 14. Blood lactate accumulation was measured during the final treadmill test. Mice were euthanized 48 hours after the last exercise session for liver histopathology, blood chemistry, and ex vivo mitochondrial function analysis. Liver function was assessed via serum liver panel and quantification of hepatic lipids. High-resolution respirometry was used to determine maximal hepatic fatty acid oxidation, NADH- and succinate-linked oxidative phosphorylation (OXPHOS), and electron transfer capacity in tissue homogenates. HFD increased body mass, which was reduced with ExT. ExT increased maximal running time independent of diet. HFD worsened lactate metabolism, which was improved with ExT. HFD increased liver weight, which was decreased with ExT. HFD-induced increases in hepatic lipid and serum ALT and ALP were reversed with ExT. Hepatic mitochondrial OXPHOS and electron transfer were reduced with HFD relative to LFD. These data suggest that exercise-induced reversal of NAFLD is not mediated by hepatic mitochondrial oxidative capacity.


E.C. Heintz: None. W.S. Dantas: None. J.E. Stampley: None. G.M. Davis: None. B.A. Irving: None. C.L. Axelrod: None. J.P. Kirwan: None.


Nutrition Obesity Research Center (P30DK072476); Louisiana Clinical and Translational Science Center (U54GM104940); Centers of Biomedical Research Excellence (P20GM103528)

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