Gray matter lipid composition

In multiple sclerosis, which is a demyelinating disease, there is loss of both phospholipids (particularly ethanolamine plasmalogen) and of sphingolipids from white matter. Thus, the lipid composition of white matter resembles that of gray matter. The cerebrospinal fluid shows raised phospholipid levels. 

O Brien, J. S. and Sampson, E. L. Lipid composition of the normal human brain gray matter, white matter, and myelin. /. Lipid Res. 6 537-544.1965. 

Central nervous system myelin is enriched in certain lipids. Table 4-1 lists the composition of bovine, rat, and human myelin compared to bovine and human white matter, human gray matter, and rat whole brain [1] (see Ch. 3). While there are no absolutely myelin-specific lipids, cerebroside (galactosyl ceramide) is the most typical of myelin. With the exception of early development,... 

The data in Table 4-1 indicate that myelin accounts for much of the total lipid of white matter, and that the lipid composition of gray matter is quite different from that of myelin. The composition of brain myelin from all mammalian species studied is very much the same. There are, however, some species differences for example, myelin of rat has less sphingomyelin than does that of bovine or human (Table 4-1). Although not shown in the table, there are also regional variations for example, myelin isolated from the spinal cord has a higher lipid-to-protein ratio than brain myelin from the same species. 

In this chapter, our intent is to review the rapid changes that take place in the cerebral cortex of n-3 fatty acid-deficient monkeys when their diet is subsequently supplied with ample dietary n-3 fatty acids. Juvenile rhesus monkeys who had developed n-3 fatty acids deficiency since intrauterine life were repleted with a fish-oil diet rich in n-3 fatty acids, DHA, and 20 5n-3 (eicosapentaenoic acid, EPA). The fatty acid composition was determined for the lipid classes of plasma and erythrocytes and for the phospholipid classes and molecular species of frontal cortex samples obtained from serial biopsies and at the time of autopsy. From these analyses, the half-lives ofDHA and EPA in the phospholipids of plasma, erythrocytes, and cerebral cortex were estimated. The deficient brain rapidly regained a normal or even supernormal content ofDHA with a reciprocal decline in n-6 fatty acids, demonstrating that the fatty acids of the gray matter of the brain turn over with relative rapidity under the circumstances of these experiments. 

The lipid composition of the brain varies slightly depending on the particular section of the brain studied (Table 1). The white matter of the brain consists primarily of myelinated neurons and myelin is predominantly sphingolipid (e.g., sphingomyelin) and cholesterol (Fig. 1). The fatty acid composition of myelin is mostly saturated and contains relatively little DHA. The gray matter of the brain, on the other hand, has very little myelin and the phosphatides PS, PE, and PI of the active neuronal membranes make up the bulk of the lipid (Salem, et al., 1986). These lipids are very unsaturated and DHA and AA are the predominant building blocks thereof. 

J. S. O Brien and E. L. Sampson, Fatty Acid and Fatty Aldehyde Composition of the Major Brain Lipids in Normal Human Gray Matter, White Matter, and Myelin, J. Lipid Res. 6, 545-551 (1965). 

O Brien JS, Eillerup DL, Mead JF. Quantification and fatty acid and fatty aldehyde composition of ethanolamine, choline, and serine glycerophosphatides in human cerebral gray and white matter. J Lipid Res 1964 5 329-338. 

F. D. Fillerup and J. F. Mead Quantification and fatty acid composition of cerebroside sulfate in human cerebral gray and white matter. J. Lipid Res. 5, 109 (1964). 

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