Effect of n-3 polyunsaturated fatty acids on gene expression associated with non-alcoholic fatty liver disease in diet-induced obese mice

Abstract

Objective To investigate the protective effect of n-3 polyunsaturated fatty acids(n-3 PUFAs) on non-alcoholic fatty liver disease caused by high fat diet-induced obese(DIO) mice. Methods Three to four-week-old male C57BL/6J mice were randomly divided into 3 groups with 15 cases in each group.These mice were fed with 2 types of high-fat diet(34.9% fat providing 60% of total energy) with n-6 PUFAs(sunflower oil) and n-3 PUFAs(fish oil) respectively to induce obesity for 20 weeks, with a normal-fat diet(4.3% fat providing 10% of total energy) as lean control group.After being fasted for 12 hours, blood samples were drawn, and livers were collected.Plasma markers, insulin, glucose, lipids, alanine aminotransferase(ALT), aspartate aminotransferase(AST), and the lipids of liver were measured by biochemical methods.The mRNA expressions of hepatic genes associated with lipid metabolism, oxidative stress, inflammation and fibrosis were examined by real-time PCR. Results As compared to the control lean mice, the plasma glucose, insulin, total cholesterol(TCH), low density lipoprotein cholesterol(LDL-C) and ALT in the DIO mice with the n-6 PUFA diet were all increased(P<0.05), and also the mRNA expressions of the hepatic genes reflecting hepatic damage, oxidative stress, inflammation and fibrosis were higher(P<0.05). As compared to the DIO mice with the n-6 PUFA diet, the above markers in the plasma and the related genes' expressions in the liver were reduced in DIO mice with the n-3 PUFA diet(P<0.05). Conclusions Dietary fish oil n-3 PUFAs may play some positive roles by antagonizing the abnormal expression of the genes associated with hepatic lipid metabolism, oxidative stress, inflammation and fibrosis in the DIO mice. Key words: N-3 polyunsaturated fatty acids; Non-alcoholic fatty liver disease; Obesity; Mouse