On the histochemistry of N-acetyl-β-D-glucosaminidase in rat central nervous system

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Abstract
The optimal conditions for histochemical demonstration of NAG activity in the cerebrum, diencephalon, midbrain, cerebellum, medulla oblangata, and spinal cord were studied in a series of 37 Wistar rats of either sex. The following more important results were obtained: Each CNS zone required a definite methodological approach. Optimal fixation for most structures was achieved after 2h treatment with formol-calcium and subsequent immersion of tissue blocks in formol-calcium 0.88 M saccharose. By this fixation technique it was possible to preserve high enzyme activity and good tissue structure. Only for the large pyramidal cells of the cerebral cortex the method of Holt provided optimal fixation. Formolcalcium-saccharose mixture and pure 0.88 M saccharose produced the opposide osmotic effect on nervous tissue previously fixed with formol-calcium: the former induced tissue shrinkage, the latter edema. The use of hexazonium p-rosaniline coupler prompted preliminary alcohol treatment of sections and introduction of 0.1 M acetate buffer in the incubation solution. Acetate buffer concentrations lower than 0.2 M diminished the difuse cytoplasmic coloration and permitted a clear-cut demonstration of the lysosomal reaction. Ample information on the distribution of NAG activity in the CNS was obtained by using fast garnet GBC coupler and 0.1 M citrate buffer. Manganese chloride in a 0.2 mM concentration activates the reaction. The distribution of NAG reaction product in the cells of the different sections of the CNS was studied. The neurons, glial cells, and blood vessels showed positive reaction. Strongest activity was reported for the neurons of the supraoptic and paraventricular nucleus, the epithelial cells of the chorioid plexus, nucleus ruber of the mesencephalon, and the vascular wall pericytes.