Effect Of Endogenous Ethanol On The Development Of NAFLD

Objectives: To observe hepatic NAS,biomedical indices,portal vein endogenous ethanol level and liver ALDH2 and ADH1 gene and protein expression,and activity of ADH1 in rats fed with normal diet,high-fat diet or high fructose diet.Furthermore,we investigate whether hepatic ALDH2 overexpression can affect the development of NASH induced by High-fat diet for rats.Methods: 1.Eighteen male Sprague Dawley rats were randomly divided into control group fed normal diet(n=6),high-fat group fed high-fat diet(n=6)and high-fructose group fed normal diet with 20% fructose water(n=6).At the end of 16 th week,nonalcoholic fatty liver disease(NAFLD)activity score(NAS)of liver tissues was evaluated.The endogenous ethanol in portal vein was detected.The mRNA levels of hepatic ADH1 and ALDH2 were detected by real time PCR.The protein levels of hepatic ADH1 and ALDH2 were detected by Western blot.The activity of ADH1 was detected by ADH1 enzyme activity kits.2.Thirty two male SD rats were divided randomly into 4 groups.They are normal group,high-fat group,high fat control adenovirus group and high fat adenovirus group.The normal group and high-fat group were fed with normal diet and high fat diet respectively for 20 weeks,other two groups fed high fat diet for 12 weeks,then high fat control adenovirus group started control adenovirus injection through tail vein since the 12 th week.Also the high-fat adenovirus group started adenovirus injection through tail vein since the 12 th week.After that,we detected the liver NAS,ADH1 and ALDH2 mRNA and protein expression levels among the groups.Results: 1.At the end of 16 th week,the NAS score,ADH1 and ALDH2 mRNA level,the protein expression level of ADH1 and ALDH2,endogenous ethanol level in the portal vein and activity of ADH1 in high-fat group were significant higher when compared with that in normal group and in high-fructose group.2.At the end of 20 th week,We found that the gene expression level and protein expression level of ALDH2 was significantly higher in the high-fat adenovirus group than the high-fat control adenovirus group and high-fat group.Furthermore,the NAS score and biomedical indices presented no significant difference among the high-fat group,high-fat control adenovirus group and high fat adenovirus group.Conclusions: 1.High-fat diet can significantly increase the endogenous ethanol levels in the portal vein,and up-regulate the expression of ADH1 and ALDH2 in the livers.2.The adenovirus overexpression of ALDH2 fail to affect the development of NAFLD.Role of endogenous ethanol in NAFLD is still in dispute.