Effect of glucose deprivation on sulfatide synthesis and oligodendrocytes in cultured brain cells of newborn mice.

Abstract

Summary: The present work was designed to develop a model for studying the effect of substrates on brain cell metabolism. The synthesis of sulfatide, a myelin lipid, which takes place predominantly in oligodendrocytes was measured in vitro in dissociated cell cultures of newborn mouse brains at 13 days in culture. This corresponds to an active stage of in vivo myelination. The effect of increasing durations of severe glucose deprivation (below 1 mM in the medium) was assessed on morphology, cellular protein, DNA, sulfatide synthesis, cerebroside sulfotransferase activity, and mucopolysaccharide synthesis. Glucose was rapidly consumed by the cultured cells above a concentration of 0.4 mM in the medium. At high and intermediate glucose concentrations, between 43.8 and 63.6% of the glucose consumed was accumulated as lactate on a molar ratio, indicating that the pyruvate dehydrogenase complex was rate limiting. In severe glucose deprivation, lactate consumption of the cultures exceeded accumulation. With increasing duration of severe glucose deprivation (below 1 mM), the following major changes were observed. The number of phase dark cells identified by immunofluorescence as oligoden-drocytes progressively decreased. Immunologically identified astrocytes apparently were unaffected by glucose deprivation. Sulfatide synthesis progressively dropped to 3.8% of control, and cerebroside sulfotransferase dropped to 10.3% of control with prolonged glucose deprivation. Thus, oligodendrocytes and one of their specific functions were damaged by glucose deprivation. Lactate, in spite of its being consumed by the brain cell cultures, was unable to replace glucose as a substrate for sulfatide synthesis. Uninfluenced by glucose deprivation were total cellular phosphocreatinkinase, arylsulfatase A, as well as total mucopolysaccharide synthesis by the brain cell cultures. Speculation: The present study shows that sulfatide synthesis in cultured brain cells of newborn mice at a stage corresponding to active in vivo myelination is dependent upon availability of glucose. Lactate, in spite of its being consumed by the brain cells, is unable to replace glucose with respect to sulfatide synthesis. This system of cultivated brain cells may serve as a model for studying other potential fuels for the maintenance of oligodendrocyte function.