Study On ?-3 PUFA Attenuating Oxidative Stress Induced By Non-alcoholic Fatty Liver Disease

Aims : The worldwide epidemic of nonalcoholic fatty liver disease(NAFLD).makes studies on the mechanisam of NAFLD being warranted.In this article,compared the effect of ?-3 polyunsaturated fatty acids(PUFA)on attenuating NAFLD with that effect of ?-6 polyunsaturated fatty acids.Methods:In animal trials,used high fat diet-induced C57 mice NAFLD module,compared to FO(fish oil)group fed with diet containing isocaloric fish oil.Also set two control groups(CON,FOCON)feeding normal chow with low content of oil/fish oil.After 24 weeks feeding,we tested the plasma contents of total triglyceride,total cholesterol,HDLC,LDLC and plasma activities of AST,ALT,SOD,GST.And collected liver tissue for histological pathological analysis.In addition,in vitro experiments adopted BRL rat liver cell as material,in order to compare the differences between effects of several PUFAs on attenuating cellular toxicity of high concentration palmitic acids.MTT test for cell viability,rhodamine 123 and DCFH-DA fluorescence staining to detect mitochondrial membrane potential and intracellular ROS level.Biochemistrical tests for introcellular GSH content and SOD activity;adopting flow cytometry to measure cell apoptosis rate;detecting genes(FASN,UQCRQ,CPT1 A,SLC25A20,PCK1)transcription and expression by realtime PCR and western blot.High performance Liquid Chromatography technology to analyze fatty acids of mitochondrial membrane phospholipid;gas chromatography tandem mass spectrum to analyze mitochondrial membrane phospholipids.Results:In this article,found that it is the fish oil,not lard,can improved the state of NALFD,such as lower the content of plasma TG,TC,LDL-C and decrease the activity of ALT?AST and GST,in the meanwhile with higher HDL-C content in plasma.Along with a better score of histochemistral analysis in liver tissue.Further in vitro experiments revealed the fact that ?-3 PUFAs(EPA,DHA & ALA)can enhanced the tolerance of liver cell on heavy load of lipids,rather then ?-6 PUFAs.Also help maintaining a sound mitochondrial membrane potential and mitochondria content in liver cells after treatment of high concentration of palmtic acid.In particular,?-3PUFA can reduced the level of intra cellular reactive oxygen species(ROS)induced by heavy load of palmitic acid.Thus ?-3 PUFAs are capable to enhance cell viability and mitochondrial function under the condition of overloaded lipids.Moreover,?-3PUFA can regulate genes expression involved in lipid oxydation and other important metabolic pathway,such as down regulate FASN expression and increase CPT1 A & SLC25A20 expression;as well as increase gluconeogenesis key enzyme PCK1 expression.Analysis also demonstrate that PUFAs can effectively integrate into mitochondrial membrane phospholipid after PUFAs supplementations in vitro.Thus lower the ratio of ?-6PUFA/?-3PUFA in membrane phospholipid.Conclusion:?-3 PUFAs cam attenuate introcellular oxidative stress,enhancing mitochondrial functions,alters mitochondrial phospholipid contents and ameliorate cell apoptosis induced by palmitic acid.?-3 PUFA can regulate energetic and substrate metabolism by modifying multiple metabolic pathway.Maybe enhencing fatty acids oxydation in association with enhenced gluconeogenesis in order to consume redundant energetic material,likely result in strengthen pentose phosphate pathway activity,subsequently increase glycogen biosynthesis and antioxidant capacity.?-3 PUFAs supplementations can lower the ratio of ?-6PUFA/?-3PUFA in membrane phospholipid,then influenceing mitochondrial membrane structure and properties,further membrane protein activity and the synthesis of bioactive compounds(such as inflammatory cytokines),finally enhencing mitochondria function,attenuating lipotoxicity;preventing inflammation and regulating activity of transcription factors.This article preliminarily laid a foundation for further study on the mechanism of this effect.