Abstract
Various chromophilic neurons in the normal and experimental anemic rabbit brain were histochemically explored with special reference to glycogen metabolism. The present observations were restricted to the brain stem including the nucleus of the mesencephalic tract of the fifth nerve, pontine reticular nucleus and dorsal nucleus of the vagus nerve. In the normal brain, the nerve cells of the former two nuclei were heterogeneously stained by basic dye from chromoneutrally to hyperchromically with close correlation with PAS positivity, while those of the last nucleus showed the homogeneous chromoneutral staining and negative PAS reaction. Under anemic condition the PAS positive hyperchromic neurons were conspicuously recognized in the pontine reticular formation and the neurons of the dorsal nucleus of the vagus nerve increased thier chromophilia and PAS positivity, but those of the mesencephalic tract of the fifth nerve slightly showed their neuronal change. In the cerebral cortex hyperchromic neurons were never observed under normal and experimental conditions.
The relation of chromophilia and glycogen metabolism is summarized as follows:
1) Moderate chromophilia (or hyperchromasia) of neuron is due to heavy staining of Nissl bodies, while PAS positive substance exclusively consits of glycogen accompanied by phosphorylase activity.
Further staining between Nissl bodies causes extreme chromophilia of neuron which is intensely stained by PAS reaction largely due to phosphorylase negative glycogen or glycoprotein, and then shrinkage of neuron further strengthens its hyperchromasia.
2) Intensity of chromophilia of the neuron fairly well corresponds to that of glucose-6-phosphate dehydrogenase activity, while activities of succinic and lactic-dehydrogenase and aldolase show the opposite relation to the chromophilia.
3) From the present results it is suggested that PAS positive hyperchromic neurons occurring in the brain stem must not be artefact but reflect their physiological and metabolic conditions.
