Feeding pure docosahexaenoate or arachidonate decreases plasma triacylglycerol secretion in rats

Essential fatty acid (EFA)-deficient rats were fed highly purified methyl esters of docosahexaenoate (22:6n-3), arachidonate (20:4n-6), alpha-linolenate (18:3n-3) or oleate (18:1n-9) (100 mg/day, tube fed for 3-10 days), and their plasma triacylglycerol (TG) secretion rates were measured. Secretion rates of TG into plasma were reduced by tube-feeding 22:6n-3, 20:4n-6, 18:3n-3, but not 18:1n-9, to EFA-deficient rats. A significant reduction occurred after feeding 22:6n-3 for only three days. Feeding 22:6n-3 or 18:3n-3 to EFA-deficient rats for three days also reduced the activities of liver lipogenic enzymes and sharply increased the proportions of 22:6n-3 and 20:5n-3 in liver phospholipid fractions. Mechanisms by which these EFA may reduce lipogenesis are discussed.