Effect of early postnatal dietary sterculate on the fatty acid composition of rat liver and brain lipids.

Pregnant rats were fed a high carbohydrate diet containing either 1% trilinolein or 1% trilinolein with 0.2% methyl sterculate from 18 day gestation to 21 day postpartum. The pups were weaned at 21 days and continued on the same diet for an additional 10 days. The microsomal stearyl CoA desaturase activities of the liver were effectively inhibited. Liver triglycerides showed increases in the saturated fatty acids concentrations at the expense of the corresponding monoenes. The concentration of cis 6-7 octadecenoic acid was elevated. In liver phospholipids, the concentration of stearic acid was increased without a corresponding decrease in the oleic acid content. A drastic decrease in the nervonic acid (24:1, n-9) concentration of liver sphingomyelin was observed. The lipids of the brain did not contain sterculic acid, and brain desaturase activity was unaffected. There was no significant change in the concentration of monoenoic acids from 16:1 to 22:1. However, nervonic acid was decreased by 32%. These results suggest that brain nervonic acid may be derived from a precursor other than oleic acid.