RESUMO
Objective: To investigate the effects of continuous exercise training (CT) and high-intensity interval exercise training (HIIT) on liver lipid metabolism and the correlation of the level of fibroblast growth factor 21(FGF21) in serum and liver tissues. Methods: Male SD rats were randomly divided into normal diet group (N) and obesity model group (H) after 1 week of adaptive feeding. Rats in the obesity model group were fed with 45% high-fat diet for about 8 weeks, and 20% weight increase compared with normal rats was considered as obesity. The rats were divided into normal diet control group (LC), normal diet HIIT group (LHI), normal diet CT group (LCT), High fat diet-induced obese control group (OC), obese HIIT group (OHI), and obese CT group (OCT) (n=10). Exercised rats were given weight-bearing swimming training intervention for 8 weeks. Blood samples were collected at least 24h after the last exercise intervention to detect the serum levels of inflammatory factors and FGF21. Liver tissue samples were collected to detect the lipid content, lipid metabolic enzyme content and FGF21 expression level. Results: Compared with LC group, the body weight, serum inflammatory factors levels and hepatic triglyceride content were increased significantly (P＜0.05). Hepatic triglyceride content was downregulated in LHI group and FGF21 expression level was enhanced in LCT group (P＜0.05). Compared with OC group, the body weight and hepatic triglyceride content were decreased significantly (P＜0.05), mitochondrial CPT-1β and β-HAD enzyme contents in liver were increased significantly (P＜0.05) in OHI group, the contents of LPL and FAT/CD36 enzyme in liver and the levels of FGF21 in serum and liver of OCT group were increased significantly (P＜0.05). Conclusion: Both exercise modes can reduce the body weight in normal and obese rats, and lipid deposition in the liver of obese rats. HIIT has a more significant effect on alleviating liver lipid deposition in obese rats by upregulating mitochondrial lipid oxidation level in normal and obese rats. CT improves the levels of FGF21 in serum and liver tissues of normal and obese rats, enhances enzyme contents that involved in fatty acids uptake to the liver, which has limited effect on alleviating lipid deposition in liver of obese rats.