ABSTRACT
The chemical characteristic of the nervous tissue is the higher level of sialylated glycolipids, essentially gangliosides, but other compounds are also present, showing a cellular specificity. For example, myelin from both the central (CNS) and peripheral (PNS) nervous tissue contains high level of galactosyl-ceramide (Gal-Cer) and of its sulfated derivative on the 3 position of Gal, the sulfatide (SO4-Gal-Cer). In contrast, glucosyl-ceramide (Glc-Cer) is virtually absent in normal conditions. Myelin contains also sialylated compounds: GM1 is the major myelin ganglioside in mammals, although its level is very low compared to that of neuronal membranes. Its actual localization in compact myelin is questioned, since its only clear localization is the areas of contacts between
The interactions between endogenous lectins and their glycoconjugate ligands play essential roles in adhesion or recognition mechanisms as well as in the regulation of cell proliferation. Such interactions occur not only during the ontogenesis of the nervous tissue (myelinating cell proliferation, neuron migration, axon fasciculation, synaptogenesis and myelination), but also in maintaining cellular contacts in the adult (myelin compaction). These essential functions can be perturbed by anomalies (genetic or not) of the biosynthesis or the degradation of glycoconjugate constituents or by auto-immune attacks against glycans or lectins. This chapter will review the glycobiological basis of several neuropathologies, discussing these effects based on the knowledge on the morphological and functional features on the nervous tissue.
