title: Dietary polyunsaturated fatty acids (C18:2 omega6 and C18:3 omega3) do not suppress hepatic lipogenesis.
abstract: Omega 3 polyunsaturated fatty acids are promoted as beneficial in the prevention of metabolic and cardiovascular diseases. In general, dietary omega 3 fatty acids are derived from plant sources as linolenic acid (LNA, C18:3 omega3) the precursor to eicosapentaenoic acid (EPA, C20:5 omega3) and docosahexaenoic acid (DHA, C22:6 omega3). However, it remains unclear if the polyunsaturated fatty acid (PUFA) LNA can provide the same health benefits as the very long chain highly unsaturated fatty acids (HUFA) EPA and DHA generally derived from oily fish. In this study, mice were fed synthetic diets containing lard (low in PUFA and HUFA), canola oil (to supply PUFA), or a mixture of menhaden and arasco (fish and fungal) oils (to supply HUFA) for 8 weeks. The diets were neither high in calories nor fat, which was supplied at 6%. The lard and canola oil diets resulted in high levels of hepatic triglycerides and cholesterol and elevation of lipogenic gene expression. By comparison livers from mice fed the fish/fungal oil diet had low levels of lipid accumulation and more closely resembled livers from mice fed standard laboratory chow. SREBP1c and PPARgamma gene and protein expression were high in livers of animals fed diets containing lard or canola oil compared with fish/fungal oil. Hepatic fatty acid analyses indicated that dietary PUFA were efficiently converted to HUFA regardless of source. Therefore, differences in hepatic lipid levels and gene expression between dietary groups were due to exogenous fatty acid supplied rather than endogenous pools. These results have important implications for understanding the regulation of hepatic lipogenesis by dietary fatty acids.
authors.affiliation: Center for Metabolic Disease, Ordway Research Institute, Albany Medical College, Albany, NY 12208, USA.
authors.forename: Whitney
authors.initials: W
authors.lastname: Sealls
authors.forename: Monica
authors.initials: M
authors.lastname: Gonzalez
authors.forename: M Julia
authors.initials: MJ
authors.lastname: Brosnan
authors.forename: Paul N
authors.initials: PN
authors.lastname: Black
authors.forename: Concetta C
authors.initials: CC
authors.lastname: DiRusso
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D064429:Fatty Acid Synthases / Q000378:metabolism; D005229:Fatty Acids, Monounsaturated / Q000008:administration & dosage / Q000494:pharmacology; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D043371:Fatty Acids, Omega-6 / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D050155:Lipogenesis / Q000187:drug effects; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size / Q000187:drug effects; D000074262:Rapeseed Oil; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004041:Dietary Fats; D004042:Dietary Fats, Unsaturated; D005229:Fatty Acids, Monounsaturated; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D000074262:Rapeseed Oil; D014157:Transcription Factors; C490333:Scd1 protein, mouse; D013230:Stearoyl-CoA Desaturase; D064429:Fatty Acid Synthases; C029310:lard