HISTOCHEMICAL STUDIES ON CARBOHYDRATE METABOLISM IN THE OLFACTORY BULB OF THE RABBIT

The present investigation was undertaken to study in detail the carbohydrate metabolism in the olfactory bulb of the rabbit. The recent histochemical methods (ALD, SDH, LDH, LDH isozymes, G6PD, and CO) were applied to the olfactory bulb of the rabbit. The olfactory glomeruli showed the most intense activity in all the layers for the mitochondrial and non-mitochondrial enzymes. The internal plexiform layer, which consists mainly of collaterals of the axons of tufted cells and mitral cells, and the axons of the internal granular cells, exhibited less activity than the layer of olfactory glomeruli. The external plexiform layer did not show so strong activity for even the mitochondrial enzymes as compared with the internal plexiform layer. The mitral cells showed variable reactions. It is suggested that the mitral cells pass through different phases of metabolic activity. Tewari and Bourne’s hypothesis1,2) concerning the relation between the nucleolus and the perinuclear concentration of oxidative enzymes is not supported by the present results. The nerve cell revealed enzyme activity in the nucleus for ALD, SDH, LDH, LDH isozymes, G6PD and CO. Glial cells also showed variable reactions for ALD, SDH, LDH, LDH isozymes, G6PD and CO. It is suggested that glial cells as well as the mitral cell of the rabbit olfactory bulb may have cyclic activity. Glial cells in and around the olfactory glomeruli showed positive reactions for all the enzymes studied. These findings may provide the support to the hypothesis (Iijima et al. 1967b)3). The histochemical distribution of LDH slow-moving isozyme (M-type) was similar to that of ALD in the mitral cell; The distribution of LDH fast-moving isozyme (H-type) was similar to that of CO and SDH in this cell