Vitamin E influences the effects of fish oil on fatty acids and eicosanoid production in plasma and circulating cells in the rat

An EPA enriched oil (MaxEPA, Seven Seas, U.K. containing 18% EPA and 12% DHA) alone or supplemented with 10 mg/ml/αtocopherol, was administered by gastric intubation at the dose of 3.2 ml/kg/day for a period of eight weeks to male rats fed a standard diet. An additional group of animals was treated with the same amount of olive oil. The administration of MaxEPA alone resulted, as expected, in accumulation of EPA and reduction of AA levels in plasma, platelet, red blood cell and PMNL phospholipids, when compared to values in the olive oil group. In addition, levels of linoleic acid were elevated, suggesting inhibition of the conversion of linoleic to arachidonic acid. Formation of i.r. TxB₂ by stimulated PRP, of i.r. 6-keto-PGF_1α by perfused aortas, and of IR LTB₄ and C₄ by stimulated PMNL were reduced, but production of Superoxide anion by PMNL was enhanced by MaxEPA treatment vs the olive oil treatment. Supplementation of MaxEPA with vitamin E caused a smaller reduction of 20:4 levels and a smaller increase of 20:5 levels in plasma and cell phospholipids and modified the effects of MaxEPA on eicosanoid and Superoxide anion production, suggesting that lipid peroxidation may mediate some of the biological effects of ω3 fatty acids.