The Characterization of Sphingolipids From Neurons and Astroglia of Immature Rat Brain¹

Isolated neuronal cell bodies and astroglia of young (15–20‐day‐old) rat brains were both found to contain small concentrations of a variety of glycosphingolipids, including glucosylceramide, galactosylceramide, sulphatide, dihexosylceramide and gangliosides. These sphingolipids, plus sphingomyelin, were isolated, quantitated and their fatty acid and long chain base patterns determined. These data were compared to similar data obtained on these lipids isolated from whole brain and myelin of rats of the same age range. Glucosylceramide was found in an amount equal to galactosylceramide in neurons, and accounted for 35 per cent of the total monohexosylceramide in astroglia. Dihexosylceramide was present in nearly the same amount as sulphatide in both cell types. The sphingolipids of each cell type had characteristic fatty acid patterns. Generally the whole brain fatty acid patterns resembled those of astroglial lipids rather than neuronal lipids. In no case did the cell sphingolipid fatty acids resemble those of myelin. However, the galactosylceramide and sulphatides of both cells had unsubstituted and α‐hydroxy acids, both of which had appreciable quantities of C 24 acids. The ganglioside fatty acids of each cell type were similar and not unusual, but were quite different from those of glucosylceramide and dihexosylceramide; the latter having appreciable quantities of 16:0 and acids longer than 18:0. The ganglioside patterns of these cells were similar and only slightly different from that of whole brain. Long chain bases of sphingolipids were mainly C 18 ‐sphingosine in both cell types, and those of ganglioside and sphingomyelin contained small amounts of C 20 ‐sphingosine.