ABSTRACT
Fatty acids play an important role not only as an energy source but also as the components of cell membrane because their composition influences membrane fluidity and the function of receptors or channels.[1] Polyunsaturated fatty acids (PUFAs) are essential for mammalians and play an important role in maintaining their physiological conditions. Metabolites of PUFAs, eicosanoids including prostaglandins and leukotrienes, regulate platelet aggregation, blood vessels construction, immune reaction, and inflammation. In addition to these roles it is well known that PUFAs, such as linoleic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), decrease plasma concentrations of cholesterol and triacylglycerol, and influence lipid metabolism.[2 – 5] Magnitude of these effects is different between the types of PUFA, for example, the numbers and the position of double bonds and their chain length. Furthermore, PUFAs, especially DHA, are related to the development of nervous system and retinal function.[6 – 8] Many studies within the past decade have shown that PUFAs function as mediators of gene transcription. One 102of the mechanisms is explained by the downregulation of sterol regulatory element binding protein (SREBP), which regulates the intracellular cholesterol metabolism.[9,10] Peroxisome proliferator activated receptor (PPAR), which binds fatty acids and their metabolites, regulates the gene expression concerned with the β-oxidation and biosynthesis of fatty acids.[11 – 14] Several other factors such as liver X receptor (LXR),[15] hepatocyte nuclear factor 4 (HNF4),[16] c-fos,and nur-77[17] are also thought to regulate the expression of genes that respond to fatty acids.
