The effects of swimming exercise on high-fat-diet-induced steatohepatitis

Aim. The aim of this study was to assess the effects of swimming exercise on high-fat (HF) diet-induced steatohepatitis. Methods. Two groups of rats were fed a HF diet (35%; kcal) for 12 weeks, with one group remained sedentary (HF-Sed) and the other group swam (HF-Tr) during this entire period. A third group was fed a standard diet and remained sedentary for 12 weeks (SD-Sed). Swimming exercise (5 days/week) was initiated at the same time as the HF diet and was progressively increased, until it reached 90 min after 4 weeks. Results. At the end of the 12-week period, HF-Sed rats exhibited higher body weight (means ± standard error [SE]: 492±40vs 432±21 g; P<0.05), liver weight (16.21±2.23 vs 9.92±1.14 g; P<0.05), serum alanine aminotransferase (73.62±36.11 vs 27.16±4.62 U/L; P<0.05), aspartic aminotransferase (AST; 198.87±120.16 vs 120.16±19.09 U/L; P<0.05), nonesterified fatty acids (NEFA; 897.48±133.62 vs 437.5 μmol/L; P<0.05), triglyceride (0.92±0.1 vs 0.56±0.04 mmol/L; P<0.05), tumor necrosis factor (TNF)-a (21.74±2.93 vs 16.57±3.53 pg/mL; P < 0.05) as well as liver malondialdehyde (MDA; 5.3±1.45 vs 3.48±0.94 nmol/mg protein; P<0.05) and NEFA (305.47±69.23 vs 204.56±64.26 μmol/mg protein; P<0.05) than SD-Sed rats. All HF-Sed rats developed moderate to severe hepatic steatosis and steatohepatitis according to liver histological findings. Compared with HF-Sed, HF-Tr rats' hepatopathological manifestations of steatosis and inflammation were much attenuated, and their serum and liver parameters were all lower with the exception of serum AST. Conclusion. It was concluded that swimming exercise might reduce the incidence of HF-diet-induced steatohepatitis.