Fatty acid and fatty aldehyde composition of the major brain lipids in normal human gray matter, white matter, and myelin

Abstract

Gray matter, white matter, and myelin were isolated from the frontal lobes of the brains of humans aged 10 months, 6 yr, 9 yr, and 55 yr. The major lipids, including ethanolamine glycerophosphatides (EGP), serine glycerophosphatides (SGP), choline glycerophosphatides (CGP), sphingomyelin, cerebroside, cerebroside sulfate, and ceramide were isolated by column chromatography and their fatty acid and fatty aldehyde compositions were determined by gas–liquid chromatography. EGP and SGP from myelin had a fatty aldehyde composition which differed from that of EGP and SGP from gray matter; octadecenaldehydes were present in much higher proportions in these lipids from myelin than in those from gray matter. EGP and SGP also contained high proportions of 20- and 22-carbon polyunsaturated fatty acids, whereas CGP contained small proportions of these acids. Each glycerophosphatide from gray matter contained approximately 3- to 6-fold higher proportions of polyunsaturated fatty acids than did the same glycerophosphatide from myelin. Sphingomyelin, cerebroside, cerebroside sulfate, and ceramide also differed in their fatty acid compositions depending upon their tissue source; each sphingolipid from myelin in the younger subjects contained 5- to 9-fold higher proportions of long-chain fatty acids (C19-C26) than did the same sphingolipid from gray matter. The lipids from myelin in the baby (10 months) were very similar to those from myelin in the adult, both with respect to their content of polyunsaturated fatty acids and to their content of long-chain fatty acids. These findings suggest that myelin in the baby is “chemically mature” in its lipid composition at an early age.