Phospholipid molecular species composition of mouse liver nuclei. Influence of dietary n-3 fatty acid ethyl esters.

The effect of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ethyl esters on the individual molecular species composition of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was determined in mouse liver nuclei. After a 10 day feeding period, there was a depletion of the sn-2 position of n-6 polyunsaturated fatty acids (PUFA) and substitution with n-3 PUFA. EPA feeding significantly increased (P less than 0.05) diacyl PC and PE 16:0-20:5, n-3, 16:0-22:6,n-3, 18:0-20:5,n-3 and 18:0-22:6,n-3 relative to control (safflower oil ethyl ester fed) animals. In comparison, DHA feeding significantly increased (P less than 0.05) 22:6 n-3-containing species, specifically 18:1-22:6,n-3, 16:0-22:6,n-3 and 18:0-22:6,n-3 in PC, and 18:1-22:6,n-3, 16:0-22:6,n-3 and 18:0-22:6,n-3 in PE. In addition, the presence of 18:0-20:5,n-3 PC in the nuclei of DHA-fed rats and of 18:2-20:5,n-3, 18:1-20:5,n-3 and 18:0-20:5,n-3 in nuclear PE indicate that incorporation of DHA retroconversion (22:6,n-3-->20:5,n-3) products. These results indicate both EPA and DHA are extensively incorporated into nuclear phospholipids, and therefore could potentially influence gene function.