Molecular characterization of gangliotetraosylceramide (GA1) in normal human brain and its developmental change

Several neutral glycosphingolipids have recently been purified from normal human brain to the criterion of migration as homogeneous bands in two different solvent systems. One of these has been permethylated and analyzed by gas chromatography. Stepwise specific exoglycosidase hydrolysis confirms its structure as GAl or Gal beta 1-->3GalNAc beta 1-->4Gal beta 1-->4Glc beta 1-->1Cer. The neutral glycosphingolipids of rat CNS have been examined in order to investigate changes in GA1 during critical ages of brain development. Employing the highly sensitive techniques of digoxigenin (DIG) immunostaining and Fluorescence Assisted Carbohydrate Electrophoresis (FACE), we have identified several previously uncharacterized long chain neutral glycosphingolipids in brain and myelin. A major band with Rf close to that of nLcOse5Cer purified from bovine erythrocytes has been identified as GA1 by immuno-TLC using mono-specific polyclonal anti-GA1 antisera. It appears in 5 day-postpartum (P5) developing brain, increases until 21 days (P21) and subsequently declines. This phasic change along with changes in other nonsialylated glycosphingolipids of the developing brain strongly suggests that GA1 and other neutral glycosphingolipids may play a mediator role(s) in brain development and/or myelinogenesis.