Selective cytochemical demonstration of glycoconjugate‐containing terminal N‐acetylgalactosamine on some brain neurons

Abstract

Paraffin embedded sections of rat, mouse, dog, and human brain were stained with a battery of lectin-horseradish perioxidase conjugates to localize and characterize glycoconjugates. In the rat and mouse cerebral cortex, a subpopulation of nonpyramidal neurons stained selectively with three lectins with specific affinity for terminal N-acetylgalactosamine (GalNAc). These and only these lectins stained the surface of the cell body, dendritic shafts, and proximal parts of the dendritic arborization. Most reactive, nonpyramidal neurons revealed a multipolar dendritic pattern, but some possibly belonged to the bitufted and bipolar types of neuron. The GalNAc-containing neurons appeared widely distributed in layers II-VI with relatively greater abundance in layers IV and V. In the cortex of rats and mice the stained neurons occurred in moderate numbers in the frontal, frontoparietal, striate, retrosplenial, and entorhinal regions, but were less numerous in the hippocampal gyrus, dentate gyrus, and olfactory area. Other neurons in the basal ganglia and brain stem stained weakly for GalNAc. Examination of the frontal cortex of human and canine brains showed a similar distribution of nonpyramidal neurons with affinity for GalNAc-binding lectins. At high magnification, the surface staining of neurons in the cerebral cortex, deep cerebellar nucleus, and other sites appeared periodic rather than continuous. The periodic character of the neuronal surface staining suggested a location for the reactive glycoconjugate in or between the synapses. The GalNAc-containing glycoconjugate occurred in a selected cell type, failed to bind the other lectin conjugates, and differed from biochemically detected glycoconjugates. It is, therefore, considered a newly recognized entity of possible physiologic significance for a population of cortical neurons.

The distribution of N-acetylgalactosamine in the cochlear nucleus of the gerbil revealed by lectin binding with soybean agglutinin

“…The observation that SBA labels specifically the surface of somata and proximal dendrites agrees well with the findings of Nakagawa et al (1986) and Kosaka and Heizmann (1989). They described that SBA labelling appeared as unevenly distributed periodic foci on the surface of the somata and dendritic shafts of nonpyramidal cells in the cerebral cortex of several mammalian species.…”

“…Fig. lb shows a typical section through the cerebral cortex of the gerbil after SBA staining to demonstrate the similarity of the present results with those of previous studies in other mammalian species (Nakagawa et al, 1986). SBA gave a distinct staining pattern in the cochlear nucleus (Fig.…”

“…The lectin from Giycine rnax (soybean agglutinin, SBA) was selected because it has been shown to selectively bind to N-acetylgalactosamine in other preparations of neuronal tissue (Nakagawa et al, 1986;Hofman and Meyer, 1991;Key and Giorgi, 1986). Endogenous peroxidase was inactivated by treatment in 0.5% H,O, in 0.1 M, pH 7.4 sodium phosphate buffer for 30 min.…”

“…It has been shown that characteristic distributions of glycoconjugates in the mammalian brain can be demonstrated by lectin cytochemistry (Nakagawa et al, 1986). Nakagawa et al (1986) described in detail the binding patterns of lectins, which are specific for ZVacetylgalactosamine, in the cortex of rat, mouse, dog and man.…”

“…Nakagawa et al (1986) described in detail the binding patterns of lectins, which are specific for ZVacetylgalactosamine, in the cortex of rat, mouse, dog and man. Extracortically, they found weak to strong binding in large cells at different brain locations.…”