Enhanced resolution of histochemical distribution of glucose-6-phosphate dehydrogenase activity in rat neural tissue by use of a semipermeable membrane.

We examined the histochemical distribution of glucose-6-phosphate dehydrogenase (G6PD) activity in neural tissue using different diffusion barriers. Although polyvinyl alcohol and agar overlays permitted regional localization of G6PD, a semipermeable membrane revealed cellular differences in G6PD activity within populations of neurons. Distribution of G6PD activity in selected regions of the nervous system was examined using the membrane technique. White matter usually exhibited strong G6PD activity. The neuronal somata of the dorsal root ganglia (L4-L6) and anterior horns of the spinal lumbar enlargement demonstrated a variation in activity which was independent of somal size. Satellite cells showed intense activity when the membrane technique was used. Hippocampal pyramidal and granular cells of the dentate gyrus exhibited moderate, uniform G6PD activity, but only weak activity was seen in hippocampal and dentate molecular layers. High levels of activity were observed in the vascular endothelial cells of the brain, spinal cord, and choroid plexus, and in the ependymal cells of the spinal central canal and ventricles of the brain. The superior vestibular nucleus appeared to have little G6PD activity in either the neuron cell bodies or the surrounding parenchyma. The use of a semipermeable membrane for localization of G6PD activity in neural tissues permits enhanced resolution of neuron elements and may provide a more accurate assessment of G6PD activity in histological preparations.