Effect of dietary N-6 and N-3 polyunsaturated fatty acids on composition and enzyme activities in liver plasma membrane of mice

Abstract

The effects of increasing amounts of dietary linoleic acid (18:2n-6) and 5 and 10 wt. % menhaden oil on the fatty acid composition and enzyme activities of mouse liver plasma membrane was studied. Groups of male mice were fed a diet containing 20 wt.% fat for 2 weeks and 15%, 35% and 47% of the total fat was composed of 18:2n-6. The increased amount of 18:2n-6 in the diet did not alter 18:2n-6, arachidonic acid (20:4n-6_ nor total polyunsaturated fatty acid (PUFA) composition of mouse liver plasma membranes. This did not affect membrane bound 5′-nucleotidase activity but moderately decreased Na +-K + ATPase activity in plasma membranes when high levels of 18:2n-6 (47%) was used in the diet. The inclusion of 5 or 10 wt% of menhaden oil in the diets containing (13%) 18:2n-6 resulted in the incorporation of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) which replaced 18:2n-6 (20–40%) and 20:4n-6 (65–80%) in the membrane phospholipids. The 5′-nucleotidase and Na +-K + ATPase activity of plasma membrane were not significantly affected by these changes in membrane fatty acid.