Binding patterns of lectins with GalNAc specificity in the mouse dorsal root ganglia and spinal cord

To localize membrane glycoconjugates in neurons of the mouse spinal cord and dorsal root ganglia (DRG), cryostat sections of newborn (P0), 7 day-old (P7), P14, P21 and P31 animals were stained with ten FITC-conjugated plant lectins, the majority of them recognizing N-acetyl-D-galactosamine (GalNAc) terminal sugar residues. In the dorsal root ganglia of P0 animals, the different lectins showed distinct patterns of labeling in either cells of the nervous system, including neurons, or other structures such as nerves or blood vessels. Moreover, some of these lectins showed important changes in their pattern of labeling during postnatal development. This was especially relevant for lectins that label a subpopulation of small-sized cells that have been previously identified as the nociceptive cells of the DRG. Enzymatic digestion of sections with neuraminidase removes sialic acid from the carbohydrate chains of glycoconjugates thus exposing novel sugar residues. When this treatment was applied to DRG sections from postnatal animals the pattern of lectin staining was either changed or eliminated and heterogeneous subsets of glycoconjugates normally masked by this sugar were exposed. In the spinal cord of PO animals, none of the lectins labeled cells in the central gray matter. However, after the enzymatic digestion of sections with neuraminidase, spinal cord motoneurons and some other cells were labeled by two of the lectins suggesting that GalNAc residues present in these cells are normally masked by terminal sialic acid. Altogether, these results show important changes in the temporal and spatial expression of glycoconjugates that may be relevant for the postnatal development of the CNS and PNS of mice.