Aerobic exercise training improves mitochondrial biogenesis and oxidative status in obese mice with nonalcoholic fatty liver disease: a non-randomized experimental study

Non-alcoholic fatty liver disease (NAFLD) is one of the most common forms of liver disease. Lifestyle modifications, such as a reduction in body weight (BW) and aerobic exercise training (AET), are effective treatments for NAFLD. The aim of the present study was to evaluate the effect of AET on hepatic oxidative metabolism in ob/ob mice. Male ob/ob mice were separated into two groups: the sedentary group (S), n=7, and the trained group (T), n=7. The T mice were submitted to an 8-week protocol of AET at 60% of the maximum velocity achieved in the running test. Before AET, no difference was observed in running capacity between the groups (S=10.4 ± 0.7 min vs. T= 13 ± 0.47 min). However, after AET, the running capacity was increased in the T group (12.8 ± 0.87 min) compared to the S group (7.2±0.63 min). Skeletal muscle in the T group (26.91±1.12 U/mg of protein) showed higher citrate synthase activity compared with the S group (19.28±0.88 U/mg of protein) (p =0.004) . BW and food consumption were significantly reduced in the T group compared to the S group (p=0.008 and p=0.001, respectively). The analysis of hepatic gene expression showed an increase in PGC-1a levels (p=0.002) and a reduction in CPT-1a levels (p=0.03). The levels of TBARs and carbonyls, as well as SOD, CAT and GST, were not different between the groups. In the nonenzymatic antioxidant system, we found that the T group had higher sulfhydryl (p = 0.02), GSH (p=0.001) and GSH/GSSG (p=0.02) activity. The activity of the metabolic enzymes citrate synthase (p=0.004) and β-HAD (p=0.01) was also increased in the T group. Besides improve in metabolism, no differences were observed in the histological analyses. In conclusion, our data demonstrate that AET improves BW control, mitochondrial functionality and oxidative metabolism in ob/ob mice.