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 about incorporation into brain and effects on CNS functions. In our experiments, mixtures of [l‐¹⁴C]‐elaidic acid and [9,10‐³H]oleic were injected intragastrically into a total of 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 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 irans‐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. Thus, intact trans‐fatty acid, elaidic acid, was incorporated into developing brain, but at slower rates than into liver. These studies establish that the developing central nervous system does not exclude dietary trans‐acids.