| Objective:(1)To examine the role of high-fructose diet in liver autophagy in MAFLD.(2)To explore the effects of aerobic exercise,dietary intervention and their combination on liver autophagy in MAFLD induced by high fructose diet.Methods: W SPF C57BL/6 mice were randomly divided into two groups,one group was fed with normal diet as control group(n=10),the other group was fed with 60% high fructose diet as MAFLD group(n=40).After12 weeks,the MAFLD group was randomly divided into model group(n=10),exercise group(n = 10),diet group(n=10)and combined group(n=10).The model group and exercise group were fed with 60% high fructose diet for 8 weeks,while the diet group and combined group were fed with common diet for 8 weeks.Exercise group and combined group were given aerobic treadmill exercise for 8 weeks.After 8 weeks of intervention,(1)body weight,abdominal viscera and fat weight were measured;(2)The changes of serum lipids and liver function were analyzed by automatic blood biochemical analyzer;(3)HE staining and oil red O staining were used to assess liver pathologies and lipid deposition.(4)Western-Blot and RT-PCR were used to detect the relative expression of Beclin-1,LC3-II,p62 and their m RNA in liver tissue.(5)The distribution of autophagosomes and lipid droplets in liver tissue was observed by transmission electron microscope.(6)To analyze the correlation between the relative expression of autophagyassociated protein m RNA and liver index,NAS.Results: Compared to the control group,the model group showed significant increases in body weight,liver index,TG,ALT,AST,LDL-C,NAS,p62 m RNA and protein relative expression(P<0.05),and significant decreases in Beclin-1 m RNA and protein expression,autophagosome number,and HDL-C(P<0.05);compared to the model group,the exercise group,diet group,and combination group showed significant decreases in body weight,liver index,TC,TG,AST,ALT,LDLC,NAS,p62 m RNA and protein expression,etc.(P<0.05),and increases in Beclin-1 m RNA and protein expression,autophagosome number,and HDL-C(P<0.05);compared to the exercise group and diet group,the combination group showed significant decreases in body weight,lipid deposition,inflammation,balloon-like change,NAS,TG,AST,ALT,and LDL-C(P<0.05);there was no difference in autophagy-related protein and m RNA relative expression between the exercise group and the diet group,and the combination group had increased Beclin-1 and Lc3-II m RNA and protein relative expression(P<0.05),and reduced p62 m RNA and protein relative expression(P<0.05);NAS was positively correlated with Beclin-1 m RNA relative expression(P<0.05)and negatively correlated with p62 m RNA relative expression(P<0.05).Conclusion:(1)Long-term high-fructose diet inhibits autophagy activity in mouse liver,resulting in massive lipid deposition and inflammation in liver tissue.(2)Exercise and diet intervention can improve the MAFLD induced by high fructose diet,reduce the body weight and dyslipidemia of mice,inhibit liver lipid deposition and inflammation,promote the expression of Beclin-1 and inhibit the expression of p62 in liver tissue of mice,activate liver autophagy and delay the progression of MAFLD,and the activation effect is more obvious when the two interventions are combined. |
