Fatty acid uptake by the brain. V. Incorporation of (I- 14 C)linolenic acid into adult rat brain.

Abstract

Abstract Linolenic acid seems to have special importance in the brain lipids since the ω-3 polyunsaturated acids are predominant brain fatty acids. Thus [I-14C]linolenic acid was fed to adult rats to investigate its passage from blood to the brain. Unlike palmitic and oleic acids that are present in large amounts linolenic acid is present in only trace amounts but its product docosahexaenoic acid is present in large amounts. Label distribution in brain docosahexaenoic acid 4 and 24 h after feeding linolenic acid showed the percentage of the total radioactivity in the carboxyl carbon was 23% and 12.4%, respectively, compared to 70.2% and 81.9% when [I-14C]acetate was injected. This pattern of distribution clearly shows that the fed material, [I-14C]linolenic acid, was incorporated into the brain lipids and directly converted into docosahexaenoic acid without appreciable oxidation to acetate. It was surprising to note that cerebrosides had a rather high specific activity when linoleic or linolenic acid were fed but not when acetate was injected.