Cerebroside

CEREBROSIDE represents a very complex, difficult-to-separate mixture of various cerebrosides and saturated brain phosphatids. Its composition includes C, H, O, N, S, and P. It possesses strong reducing ability, depending on the presence of d-galactose. When cooling an alcoholic extract of the brain, P. immediately precipitates as a crystalline sediment—"substance blanche" of Vauquelin. For some time after Liebreich (1865), it was believed that all lipoid substances of the brain are formed from P. By repeated recrystallization from alcohol, it is impossible to change the chemical composition of P., and this was the basis for considering P. as a perfectly definite chemical compound. In reality, however, P. can be separated into its constituent parts by the use of various organic solvents, such as chloroform, benzene. It can serve as a starting product in the preparation of phrenosine, sphingomyelin, and cerebrosides. At present, apparently not all substances included in its composition have been studied. The content of P. is not the same in the normal and pathologically altered brain (progressive paralysis, early and senile dementia, etc.). It increases with age both during the embryonic and post-embryonic development of the organism. Degeneration of the peripheral nerve, caused by its sectioning, is associated with a gradual decrease in the amount of P. Recent works (chiefly by Winterstein and his school) on the study of the isolated brain in its state of rest, upon its irritation and excitation, speak of the important role of the components of P. (cerebrosides) in the metabolism of the brain.