The quantitative estimation of cerebrosides in nervous tissue.

TLDR: The values for cerebrosides found in the current literature include gangliosides, and other investigators (JOHNSON, MCNABB, and ROSSITER, 1950; CUMINGS, 1953; BLACKWOOD and CUMings, 1954) have neglected the ganglariosides.

Abstract: THE extensive research work in the physiological and pathological processes in which lipids are involved has increased the necessity for accurate micromethods for their quantitative estimation. BRANTE (1949) reviewed modern micromethods for the determination of the lipids in nervous tissue, and made a thorough investigation of the various factors which may influence them. Like most other investigators, BRANTE determined the cerebroside content only by estimating the reducing substances in a lipid extract before and after hydrolysis. From the important work of KLENK and collaborators (KLENK, 1941, 1942; KLENK and LANGERBEINS, 1941 ; SCHUWIRTH. 1940) we know that cerebrosides are not the only lipids containing carbohydrates in the central nervous system. They have isolated gangliosides from the brain and determined their amount in different nervous tissues. Besides these two glycolipids, a third has been described by ARSOVE, FOLCH, and MEATH (1951a). They named the new lipid strandin, but my preparations like DAWN'S (1952), showed that strandin consisted of gangliosides in a different physico-chemical state contaminated with low-molecular substances and mucopolysaccharides. CHATAGNON and CHATAGNON (1953, 1954) have suggested that sphingomyelin is also a part of the complex. BRANTE (1949) discussed the interference of gangliosides on the cerebroside values, and we (BRANTE and SVENNERHOLM, 1949, 1951) determined both total glycolipids and gangliosides in some foetuses. Other investigators (JOHNSON, MCNABB, and ROSSITER, 1950; CUMINGS, 1953; BLACKWOOD and CUMINGS, 1954) have neglected the gangliosides. Therefore the values for cerebrosides found in the current literature include gangliosides. EDGAR (1955) who has thoroughly discussed the problem, used the term glyco-sphingosides instead of cerebrosides. He has also made some estimations of both gangliosides and cerebrosides. Consequently, the carbohydrates in a lipid extract are derived from at least two lipid sources. But lipid extracts are contaminated to some extent with low-molecular substances, partly of carbohydrate nature. It is impossible to remove them completely by the methods generally used, i.e., precipitation of the lipids before extraction or re-extraction of a primary lipid extract. Generally, the error introduced by the contaminants is negligible i n the determination of glycolipids in adult nervous tissue, but this is not so in foetal tissue, where the amount of glycolipids is low and that of the contaminants is both relatively and absolutely higher. FOLCH, ASCOLI, LEES. MEATH, and LEBARON (1951b), however, succeeded in removing these substanccs by partition dialysis. By this procedure the gangliosides too are separated from the other lipids. It therefore appeared that it might be possible to use this method to separate cerebrosides from other substances containing carbohydrates.