Human fetal brain contains galactosylceramide/glucosylceramide (48%), lactosylceramide (17%), two trihexaosylceramides (12%), fuconeotetraosylceramide (10%) and neolactotetraosylceramide (13% as neutral glycosphingolipids (ngsls). We recently characterized a gangliotetraglycosylceramide (GgOse4Cer) and a globopentaglycosylceramide (Ga1GbOse4Cer) from bovine brain. Although GgOse4Cer has been detected by immunohistology in mouse brain myelin, it has not previously been characterized analytically. This project examines the ngsls from normal adult brain and has the following specific aims: (1) Characterization of ngsls from bovine brain and comparison of the ngsls of human and rat brain; (2) Characterization of ngsls expressed during brain development; (3) Putative regulation of carbohydrate expression by specific glycosidases and glycosyltransferases; (4) Delineation of the topographic distribution of ngsls by immunohistology. The ngsls will be purified and characterized by chemical and biochemical methods. Enzyme activity will be assayed using radioactively-labelled glycolipid substrates. Ngsls expression during brain development will be examined both qualitatively and quantitatively. Specific carbohydrate antigens will be determined by immunohistology of ngsls at different brain developmental stages using fluorescent antibodies and lectins. Our long-term goal is to evaluate the role of such carbohydrate antigens in developmental disorders and other neurological and demyelinating diseases including multiple sclerosis and polyneuropathy.
