Physical exercise prevents and mitigates non-alcoholic steatohepatitis-induced liver mitochondrial structural and bioenergetics impairments

Exercise is considered a non-pharmacological tool against several lifestyle disorders in which mitochondrial dysfunction is involved. The present study aimed to analyze the preventive (voluntary physical activity-VPA) and therapeutic (endurance training-ET) role of exercise against non-alcoholic steatohepatitis (NASH)-induced liver mitochondrial dysfunction. Sixty male Sprague-Dawley rats were divided into standard-diet sedentary (SS, n = 20), standard-diet VPA (SVPA, n = 10), high-fat diet sedentary (HS, n = 20) and high-fat diet VPA (HVPA, n = 10). After 9 weeks of diet-treatment, half of SS and HS animals were engaged in an ET program (SET and HET) for 8 weeks, 5 days/week and 60 min/day. Liver mitochondrial oxygen consumption and transmembrane-electric potential (ΔΨ) were evaluated in the presence of glutamate-malate (G/M), palmitoyl-malate (P/M) and succinate (S/R). Mitochondrial enzymes activity, lipid and protein oxidation, oxidative phosphorylation (OXPHOS) subunits, cytochrome c, adenine nucleotide translocator (ANT) and uncoupling protein-2 (UCP2) content were assessed. HS groups show the histological features of NASH in parallel with decreased ΔΨ and respiratory control (RCR) and ADP/O ratios (G/M and P/M). A state 3 decrease (G/M and S/R), FCCP-induced uncoupling respiration (S/R) and ANT content were also observed. Both exercise types counteracted oxygen consumption (RCR, ADP/O and FCCP-uncoupling state) impairments and improved ΔΨ (lag-phase). In conclusion, exercise prevented or reverted (VPA and ET, respectively) the bioenergetic impairment induced by NASH, but only ET positively remodeled NASH-induced liver structural damage and abnormal mitochondria. It is possible that alterations in inner membrane integrity and fatty acid oxidation may be related to the observed phenotypes induced by exercise.