MODIFICATION OF SPLEEN PHOSPHOLIPID FATTY-ACID COMPOSITION BY DIETARYFISH-OIL AND BY N-3 FATTY-ACID ETHYL-ESTERS

We have compared the effects of diets containing purified ethyl esters of either eicosapentaenoic acid, docosahexaenoic acid, or a mixture o f both of these compounds, with diets containing either purified fish oil or beef tallow on spleen phospholipid fatty acid composition. Auto immune mice, the (NZB x NZW)F1 strain, were fed with experimental diet s for 14 weeks, after which spleen phospholipids were extracted and se parated into classes by HPLC, and the alkenylacyl, alkylacyl, and diac yl subclasses of glycerylphosphatidylethanolamine and glycerylphosphat idylcholine were resolved as their benzoyl esters by HPLC. Fatty acids were analyzed by capillary gas-liquid chromatography of their methyl esters. Each of the marine lipid diets suppressed n-6 fatty acids and elevated n-3 fatty acids in all phospholipids. The eicosapentaenoic ac id ethyl ester diets led to high levels of eicosapentaenoic acid and d ocosapentaenoic acid (C22:5n-3), but little or no increase in docosahe xaenoic acid. The docosahexaenoic acid ethyl ester diets elevated doco sahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid in all phospholipids, indicating that extensive retroconversion of 22 car bon n-3 fatty acids had occurred. These results document changes in th e fatty acid composition of mammalian phospholipids that are induced b y dietary fish oil triglycerides and by dietary long chain n-3 fatty a cid ethyl esters.