Sealls Whitney, Gonzalez Monica, Brosnan M Julia, Black Paul N, DiRusso Concetta C
Center for Metabolic Disease, Ordway Research Institute, Albany Medical College, Albany, NY 12208, USA.
Biochim Biophys Acta. 2008 Aug;1781(8):406-14. doi: 10.1016/j.bbalip.2008.06.010. Epub 2008 Jul 4.
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.
ω-3多不饱和脂肪酸被认为对预防代谢性疾病和心血管疾病有益。一般来说，膳食中的ω-3脂肪酸来源于植物性来源，如亚麻酸（LNA，C18:3 ω3），它是二十碳五烯酸（EPA，C20:5 ω3）和二十二碳六烯酸（DHA，C22:6 ω3）的前体。然而，尚不清楚多不饱和脂肪酸（PUFA）亚麻酸是否能提供与通常来源于油性鱼类的超长链高度不饱和脂肪酸（HUFA）二十碳五烯酸和二十二碳六烯酸相同的健康益处。在本研究中，给小鼠喂食含猪油（PUFA和HUFA含量低）、菜籽油（提供PUFA）或鲱鱼油和阿拉斯加鳕鱼鱼油混合物（提供HUFA）的合成饲料8周。这些饲料的热量和脂肪含量都不高，脂肪含量为6%。猪油和菜籽油饲料导致肝脏甘油三酯和胆固醇水平升高以及脂肪生成基因表达增加。相比之下，喂食鱼/鱼油饲料的小鼠肝脏脂质积累水平较低，更类似于喂食标准实验室饲料的小鼠肝脏。与鱼/鱼油饲料相比，喂食含猪油或菜籽油饲料的动物肝脏中SREBP1c和PPARγ基因及蛋白表达较高。肝脏脂肪酸分析表明，无论来源如何，膳食中的PUFA都能有效地转化为HUFA。因此，不同饮食组之间肝脏脂质水平和基因表达的差异是由于外源脂肪酸的供应而非内源性储备。这些结果对于理解膳食脂肪酸对肝脏脂肪生成的调节具有重要意义。
