Effects Of Aerobic Exercise On Preventing HFD-induced NAFLD In C57BL/6Mice

ObjectiveThe study aimed to investigate the effect of aerobic exercise on preventingthe nonalcoholic fatty liver disease (NAFLD) induced by feeding high-fat dietand improving the expression of lipid metabolism-associated genes.MethodsForty-two male C57BL/6mice were randomized into four groups (n=8-13):normal diet sedentary group (ND)(n=8), normal diet exercised group (ND-Ex),high-fat diet sedentary group (HFD) and high-fat diet exercised group (HFD-Ex).Simultaneously to starting high-fat diet feeding, the mice were submitted to anaerobic swimming training protocol (60minutes/day) five days per week, for12weeks. At the end of the experiment, the mass of fat was determined byquantitative magnetic resonance body composition analyzers. mice liver, bloodtriglycerides and total cholesterol, fasting blood glucose, oral glucose tolerancewere determined. The neutral fat deposited in the liver was measured by OilRed O staining. The level of Akt phosphorylation in liver was measured byWestern blot. The expression of lipid metabolism-associated genes weremeasured by RT-qPCR.Results1. Compared with group ND, group HFD had significantly higher body weight,impaired oral glucose tolerance, dyslipidemia, liver steatosis and NAFLD (P<0.05).Compared with group HFD, aerobic exercise reduced overweight and all the otherworst findings, especially NAFLD (P<0.05).2. The mass of fat: Compared with group ND, mass of fat was increased ingroup HFD (P<0.01). Compared with group HFD, mass of fat was reduced in groupND-Ex (P<0.01).3. Oil Red O staining: In group HFD, there is neutral fat depositing in liver. Butother three groups had not. 4. The level of Akt phosphorylation in liver: Compared with group ND, the levelof Akt phosphorylation in liver was reduced in group HFD (P<0.01). Compared withgroup HFD, it was increased in group ND-Ex (P<0.01).5. Genes about fatty acid transport: Compared with group ND, the expressionsof CD36and LFABP were increased (P<0.01), but the expression of FATP5had nochange in group HFD. Compared with group HFD, the expressions of CD36andLFABP were reduced (P<0.05), but the expression of FATP5had no change ingroup ND-Ex.6. Genes about lipogenesis: Compared with group ND, the expressions of FAS(P<0.05) and SCD1(P<0.01) were increased, but the expression of ELOVL6hadno change in group HFD. Compared with group HFD, the expressions of ELOVL6(P<0.05), FAS (P<0.01) and SCD1(P<0.01) were reduced in group ND-Ex.7. Genes about fatty acid β-oxidation: Compared with group ND, theexpressions of PPARα and CPT-1α were increased (P<0.01), but the expression ofAOX had no change in group HFD. Compared with group HFD, the expression ofAOX was increased (P<0.01), but the expressions of PPARα and CPT-1α had nochange in group ND-Ex.8．The expression of ChREBP：Compared with group ND, the expression ofChREBP was increased (P<0.01) in group HFD. Compared with group HFD, theexpression of ChREBP was reduced (P<0.01) in group ND-Ex.Conclusions1. High-fat-diet can induce NAFLD and glucose metabolism disorder.Aerobic exercise can prevent these induced by high-fat-diet.2. Aerobic exercise can prevent the suppression of Akt signaling andinsulin resistance in liver induced by high-fat-diet.3. Aerobic exercise can reduce neutral fat depositing in liver though theeffect on the expression of lipid metabolism-associated genes in liver, andprevent high-fat-diet induced NAFLD.4. The effect of aerobic exercise on the expressions of FAS and SCD1maybe related with the effect of aerobic exercise on the expression of ChREBP.