REGIONAL BRAIN EFFECTS OF SODIUM-AZIDE TREATMENT ON CYTOCHROME-OXIDASE ACTIVITY - A QUANTITATIVE HISTOCHEMICAL-STUDY

The objective of the present study was to determine if regional variat ion in brain cytochrome oxidase activity was observed following system ic administration of sodium azide. An image analysis system calibrated with internal standards of known cytochrome oxidase activity was used to quantify cytochrome oxidase in histochemically stained brain secti ons. Rats receiving chronic infusion of sodium azide (400 mu g/hr), wh ich were sacrificed after two weeks, showed a substantial decrease in brain cytochrome oxidase activity over those infused with saline. All of the 22 regions sampled from telencephalic, diencephalic, and mesenc ephalic levels, showed a significant activity reduction which ranged b etween 26% and 37%. The regions that appeared significantly more vulne rable to the sodium azide effects were the mesencephalic reticular for mation and the central amygdala, which displayed the largest decrease in activity. In addition, interregional correlations of activity showe d a deeply modified pattern of correlative metabolic activity between hippocampal, amygdaloid and cortical areas after azide treatment. The regional effects found were consistent with azide-induced learning and memory dysfunctions.