Structure and functions of lectins in the central and peripheral nervous system

There is increasing evidence that lectins are widely distributed in mammalian tissues, including the nervous tissue. Based on histochemical techniques using neoglycoproteins, different lectin activities specific for different monosaccharides or glycans have been identified (fucose, galactose, mannose, N-acetylglucosamine, N-acetylgalactosamine, N-acetylneuraminic acid and heparin). Most of them showed a cellular specificity and developmental regulation in the central nervous system. Several lectins isolated from the nervous tissue seem to play an essential role during ontogenetic processes, especially as far as cell adhesion and cell recognition mechanisms are concerned (axonal growth and fasciculation, neuron migration, synaptogenesis, myelination). But some of them seem to be involved in signaling events both intracellularly (nuclear lectins) or at the cell surface by autocrine and paracrine mechanisms. This review discusses the structure and the identified functions of these important constituents of the nervous tissue.