Metabolism of sulfogalactosyl glycerolipids in the myelinating mouse brain

The in vivo metabolism of sulfogalactosyl glycerolipids (SGG) was studied in the cerebrum and cerebellum of developing mice after intraperitoneal injection of [35S]sulfate. After correction for the specific radioactivity changes of blood sulfate the quantitative rates of biosynthesis and biodegradation of this lipid could be determined. In addition, the net accumulation of SGG was measured. Throughout development the rates of SGG biosynthesis and net accumulation were higher in the cerebellum than in the cerebrum. The developmental patterns of SGG net synthesis in both parts of the brain were closely related to those observed earlier for sulfatide. During development the rate of SGG biosynthesis in both parts of the brain showed a peak earlier than that of sulfatide (at 14 days versus 20 days). The in vivo patterns of SGG degradation followed those of biosynthesis in the cerebrum and cerebellum. During postnatal development 40 to 80% of the daily synthesized SGG disappeared within 24 hr, suggesting that degradation may also be involved in the regulation of SGG net synthesis during myelination, as previously indicated for sulfatide.