THE CHARACTERIZATION OF SPHINGOLIPIDS OF OLIGODENDROGLIA FROM CALF BRAIN

Abstract— Purified oligodendroglia isolated from bovine brain white matter were found to contain, in addition to galactosylceramide, sulfatide and sphingomyelin, significant quantities of glucosylcerai‐mide, dihexosylceramide and esterified galactosylceramide. These sphingolipids were isolated and quan‐titated and their fatty acid and long chain base patterns compared with those from sphingolipids isolated from bovine myelin, white matter and gray matter. The minor glycosphingolipids, glucosylceramide, dihexosylceramide and esterified galactosylceramide, constituted a higher percentage of glial lipids than of myelin lipids. Glucosylceramide accounted for 12% of the total glial monohexosylceramide fraction and 0.8% of total lipids; dihexosylceramide was 0.9% of total glial lipids. Both of these lipids had small quantities of α‐hydroxy fatty acids. The unsubstituted fatty acids of glucosylceramide were mostly short chain (16 and 18 carbons) and were different from those of the dihexosylceramides which were a mixture of short and long chain. The hydroxy acids of each of these lipids were, however, similar and resembled those of galactosylceramide. The fatty acid patterns of galactosylceramide, sulfatide and sphingomyelin from glial cells resembled those of the corresponding lipids from myelin and white matter. The amide‐linked acids of esterified galactosylceramide contained both unsubstituted and α‐hydroxy chains. Their patterns were not identical to those of galactosylceramide, but were similar in all brain fractions. With the exception of sphingomyelin and dihexosylceramide, which contained small amounts of C20‐sphingosine, all sphingolipids analyzed contained mostly sphingosine and dihydrosphingosine. We conclude that the distribution of sphingolipids in the oligodendroglia is characteristic, but the lipophilic residues of these lipids are not cell‐specific.