Comparative Effects of Eicosapentaenoic Acid and Docosahexaenoic Acid on n-6 and n-3 Fatty Acid Profiles of Phospholipid Classes in Several Tissues of Rats Fed a Hypertriglyceridemic Diet.

Dietary hypertriglyceridemic rats were treated with refined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and changes in the n-6 and n-3 polyunsaturated fatty acid (PUFA) profiles in phospholipid (PL) classes in their tissues were analyzed in various aspects. The effects of EPA on the PUFA profiles in tissue PL classes were different from those of DHA. The effects were manifested differently depending on tissues and on the PL classes even in the same tissue. A decrease in the proportion of n-6 PUFA and an increase in the proportion of n-3 PUFA were both marked, particularly in the liver and heart, due to treatment with EPA and DHA; whereas these changes were somewhat slighter in the testes and were hardly observed in the brain. The variation pattern of tissue difference in the individual PUFA of each PL class differed, depending on the kind of PUFA, among the control, EPA, and DHA groups. The variation pattern of PL class difference in the individual PUFA of each tissue showed a similar tendency. Suppression of metabolic conversion from linoleic acid to arachidonic acid was not uniform depending on the tissue and also on the PL class, but the effect of DHA was more intense compared with that of EPA. On the other hand, the ratio of n-3 PUFA/total PUFA (n-3/PUFA) was largest in phosphatidylethanolamine, following by phosphatidylcholine and cardiolipin, in all the tissues, and was larger in the DHA group than in the EPA group. These findings suggest that a large uptake of n-3 PUFA by the liver PC and PE classes may decrease the secretion of VLDL-TG from the liver and may be related to the decrease of serum triglyceride.