INCORPORATION AND METABOLISM OF THE DIETARY TRANS-UNSATURATED FATTY-ACID, ELAIDIC ACID, BY DEVELOPING RAT-BRAIN

Trans-unsaturated fatty acids, geometrical isomers of naturally occurring cis-acids, are dietary components and are incorporated into complex lipids of many tissues. There is little information on incorporation into brain and effects on CNS functions. Mixtures of [1-14C]-elaidic acid and [9,10-3H]oleic were injected intragastrically into 34 rats at 6, 12 and 16 days of age. Animals were killed 4, 8, 24, 48 and 96 h after administration and brain and liver lipids were analyzed. With all ages examined, about 0.02-0.22% of the administered radioactivity from each fatty acid was found in brain lipids with incorporation increasing with time after administration. Phospholipids accounted for 60-85% of the total label from both fatty acids; of this phospholipid label, 40-50% of the 14C was in unaltered trans-monoene. Up to 22% of the total 14C label recovered from brain was in cholesterol. By contrast to brain, labeling of liver lipid was much greater and was highest at 4 h after administration; there was proportionally less 14C or 3H label in palmitate and cholesterol compared to brain. Intact trans-fatty acid, elaidic acid, was incorporated into developing brain, but at slower rates than into liver. These studies establish that the developing CNS does not exclude dietary trans-acids.