Effects of Dietary and Hiit on Lipid Metabolism of the Liver Tissue in Obese Rats

PURPOSE: This study aimed to investigate the effects of diet and High Intensity Interval Training (HIIT) on body mass gain, serum inflammatory markers and hepatic lipid metabolism of obese rats. METHOD: Male Sprague-Dawley rats were fed with a normal standard diet (N) or a high fat diet (H; 45% kcal as fat) for eight weeks without exercise stimuli. Obese rats were defined as increased at least 20% body weight than normal diet rats. Normal diet rats were then continue fed with a normal diet (N), and half of obese rats were fed with a normal diet (ON), while the other half were continue fed with a high-fat diet (OH). Each diet type group was then divided into two subgroups, control (NC, ONC, OHC groups) and High Intensity Interval training (NHI, ONHI, OHHI groups) (n=10-12). The HIIT training consisted of a swimming exercise performed over eight weeks. RESULTS: Obese high fat diet rats showed greater body weight, visceral adipose mass, serum lipid levels (LDL, TG, TC), and inflammatory markers(MCP-1,IL-1β,TNF-α)in values than normal diet rats, but were significantly reduced with HIIT, but this phenomenon was not observed in obese normal diet rats, except MCP-1. In addition, compared to normal rats, OHC group rats exhibited high levels of hepatic wet weight and liver triglycerides, but not in ONC group. HIIT significantly deceased liver TG content compared with control groups, which consistent with liver oil red O stain images. Moreover, compare to the control groups, mitochondrial CS activity and the biogenesis marker PGC-1α expression were upregulated with HIIT in obese high fat diet rats, meanwhile, the activity of mitochondrial fatty acid oxidation enzymes, include CPT-1α,β-HAD were significantly increased in HIIT groups. However, the activity of LPL and FAT/CD36 enzymes, which are key regulators of tissue fatty acid uptake from plasma were not changed with HIIT. CONCLUSION: HIIT was shown to be effective in controlling body weight, adiposity levels and serum lipid contents in high-fat diet fed obese rats, HIIT displayed positive effects on mitochondrial lipid oxidation enzyme activities and significantly attenuated lipid accumulation of liver tissue in obese rats. Additionally, diet and exercise was more effective than exercise alone in reducing body weight, VAT mass, serum inflammatory and liver TG content.