Effects Of Branched Chain Fatty Acids Iso-15:0 And Iso-18:0 In Vitro And Its Mechanism

Objective: It was aimed to explore the lipid-lowering effect of two branched chain fatty acids(BCFA),iso-15:0 and iso-18:0,and study the mechanisms involved so as to deepen our understanding of the biological activity of BCFA and their application,and also provide new clues for the development of natural drugs or health food for nonalcoholic fatty liver disease(NAFLD)control.Methods: To establish a cell model for investigating hepatic steatosis in vitro,L02 cells were exposed to a mixture of free fatty acids(FFA)(oleates: palmitates=2:1).The morphology of lipid droplets,triglyceride(TG)level and cell proliferation rate were evaluated by using Oil Red O staining,GPO-PAP and MTT methods,respectively.Then established cell model were treated with different concentrations of iso-15:0 and iso-18:0BCFA,respectively,and the TG-lowing effects were observed by determination of total lipid content and TG level.Furthermore,m RNA levels of several key factors of lipid metabolism(PPAR-?,CPT1,CPT2,ACOX1,SREBP-1c,ACC,m TOR,FASN m RNA)and protein levels of PPAR-?,CPT1,SREBP-1c,ACC,AMPK and P-AMPK were examined by using q PCR and Western Blotting methods to explore the molecular mechanisms of iso-15:0 and iso-18:0.The data were statistically analyzed using software SPSS 19.0,and P < 0.05 was considered to be statistically signi?cant.Results:(1)After treated with 1 m M FFA for 24 h,L02 cells showed a markedly increased level of TG without significant changes of cell proliferation rate,which indicated that the hepatic steatosis cell model was successfully established.(2)Both iso-15:0 and iso-18:0BCFA could decrease the lipid content in the established cell model.(3)iso-15:0 and iso-18:0 BCFA played their roles through suppression of SREBP-1c,ACC and FASN.In addition,incubation with iso-15:0 and iso-18:0 BCFA up-regulated the expression of lipolytic enzyme,CPT1,CPT2,PPAR-?,ACOX1,AMPK.Conclusions: Iso-15:0 and iso-18:0 can significantly decrease the level of TG in a hepatic steatosis cell model.Suppression of hepatic cell fatty synthase,SREBP-1c,ACC and FASN etc,and up-regulation of the expression of catabolismenzyme,like CPT1,CPT2,PPAR-?,ACOX1 etc,may account for the molecular mechanism for the biological activity.Also,iso-15:0 and iso-18:0 are able to activate the AMPK pathway,leading to a decrease in the rate of lipid synthesis but an increase in the rate of breakdown of lipids in cells.