Abstract
Endogenous diaminobenzidine (DAB)-positive granules in the astrocyte of rat brain were demonstrated with the peroxidase histochemical method slightly modified by us. The most prominent accumulation of endogenous DAB-positive granules was present in the astrocytic cytoplasm and astrocytic processes of the lateral and ventral marginal zone of area postrema, olivary nucleus, hypothalamic arcuate nucleus, fimbria hippocampi, subependymal periventricular region, stria medullaris thalami and cerebellar flocculus. Astrocytes containing a moderate amount of DAB-positive granules were demonstrated in the olfactory bulb, neocortex, corpus callosum, basal ganglia and other regions of the rat brain.
Histoenzymological characteristics of endogenous DAB-positive granules include presence of a “pseudoperoxidase” (hemoglobin-like peroxidase) and a native organelle in the astrocyte itself. Their activity, however, exhibits a 6.5 to 7.6 optimal pH and is inhibited with KCN, CuSO4 and HIO4-NaBH4. Contrarily, this activity was not inhibited where treated with boiling water.
The histochemical fine structural finding showed a presence of distinctive highly electron dense bodies, 0.4 to 1.6μm in diameter, located in the astrocytes and their processes. Highly electron dense reaction products for DAB were also found and may have a possible relation with the lipid-like dense bodies.
