Protective Effect Of Apigenin On Nonalcoholic Fatty Liver Disease And Its Mechanism

At present,non-alcoholic fatty liver disease(NAFLD)has become one of the major causes of chronic liver disease in western countries.However,the incidence of the NAFLD in our country also shows an obvious rising trend in recent years.Although researchers have established a certain basis for the pathogenesis of NAFLD and the use of existing drugs to treat with NAFLD,clinical data on the therapeutic effects of drugs is not enough.Long-term use of some drugs will cause obvious toxic side effects.These factors have greatly limited the research progress and strategic application of NAFLD drugs.Apigenin is a common,low-toxic,food-derived flavonoid.Much research data showed that apigenin has a variety of biological activities,such as antioxidant,anti-inflammatory,antiviral,antibacterial and anti-tumor.Based on the antioxidant and anti-inflammatory activities of apigenin,we will preliminarily elucidate the mechanism of apigenin’s protective effect on NAFLD in vivo and vitro NAFLD models in this study1.The liver protection effect of apigenin on mice fed with a high fat dietIn this study,mice model of NAFLD was established by feeding male C57BL/6 mice with a high-fat diet for 16 weeks.Mice in the high-fat diet model group and the corresponding administration group fed with a high-fat diet.After 12 weeks,administration group were administrated apigenin(50 mg/kg)and positive control drug allopurinol(5 mg/kg)by gavage every day,the administration cycle was 4 weeks.The normal group fed with normal water and food for 16 weeks.Our results showed that the weight and liver/body weight of the mice in the high-fat model group were higher than normal group after the experiment.Meanwhile,the liver color is changed from dark red to khaki yellow and feels greasy.Further serological tests showed that serum AST,ALT,TG and TC levels were significantly increased,suggesting that long-term high-fat diet could induce liver injury.Compared with the high-fat model group,apigenin(50 mg/kg)significantly reduced the body weight,serum AST,ALT,TG and TC levels of mice after 4 weeks of apigenin administration.The liver color tends to be normal.The results indicated that apigenin had a protective effect on liver injury induced by high-fat diet.2.The effect of apigenin on the improvement of lipid accumulation in NAFLDIn this experiment,hematoxylin-eosin(HE)was used to stain the liver tissue of mice,the results showed that large vacuoles were found in the liver of mice in the high-fat diet group,suggesting that severe steatosis was occured in the liver of mice.In addition,the results of oil red O staining of liver sections of mice showed that large areas of red lipid droplets appeared in the liver of mice in the high-fat feed model group,indicting that the liver of the high-fat diet mice was accumulated with a large amount of lipid.These results indicated that the mice NAFLD model has been successfully established.These phenomenon were significantly improved after the administrated of apigenin,indicating that apigenin could alleviate liver steatosis and lipid accumulation induced by high-fat diet.In addition,this experiment also clarified the phenomenon of apigenin reducing lipid accumulation induced by high-fat feed at the molecular level.Our results found that apigenin could inhibit the expression of lipogenic genes such as srebp-1,Fasn and Ppar-y.At the same time,the same results also found in the cellular NAFLD model which was established with 0.5 mM free fatty acid(FFA).All of these results suggesting that apigenin can alleviate the accumulation of lipid in the liver by inhibiting the expression of lipogenic genes.3.The liver protective effect of apigenin on NAFLD and its mechanism.Compared with the normal group,the levels of inflammatory cytokines Il-6,TNF-,Ccl2 and Ccr2 in the liver of NAFLD mice induced by high-fat diet were significantly increased,which was consistent with the phenomenon of accumulation of activated macrophages identified by F4/80 positive staining and observed by KCs immunohistochemistry.ELISA results showed that the levels of IL-1β and IL-18 in serum and liver were significantly higher than normal mice.All of these indicated that long-term high-fat diet could induce liver inflammation.In this study,we found that the above phenomenon was significantly improved after adminstration of apigenin,indicating that apigenin can alleviate the liver inflammation induced by high-fat diet.Consistent with the high levels of IL-1β and IL-18 in the liver and serum,the NLRP3 inflammasome was activated in the NAFLD model induced by high-fat diet,while the activation of the NLRP3 NLRP3 inflammasome was inhibited after adminstration of apigenin.Compared with high-fat diet group,the liver XO activity and its catalytic products uric acid and ROS levels were significantly higher than normal group,but apigenin adminstration could significantly inhibit XO activity,uric acid and ROS production.These results suggest that XO may be the key to mediate apigenin and allopurinol resistance to oxidative stress and inflammation induced by high-fat diets.In summary,apigenin and allopurinol may have therapeutic effects on NAFLD by inhibiting XO activity in hepatocytes,which further inhibiting the activation of NLRP3 inflammasome,and reducing IL-1β and IL-18,thereby alleviating hepatic inflammatory injury.