HISTOCHEMICAL-LOCALIZATION OF SUPEROXIDE-DISMUTASE ACTIVITY IN RAT-BRAIN

Histochemical localization of superoxide anion (O-2(.-)) scavenging ac tivity in rat brain was visualized by the tissue-blotting technique. T he activity was thought to mainly depend on Cu/Zn-SOD, because the loc alization of the activity was identical with the immunohistochemistry of Cu/Zn-SOD and the localization of its mRNA in the brain. Moreover. the activity was dramatically decreased after treatment of Cu (I) chel ater, The activity was detected in pyramidal cells of the cortex, gran ular, and mitral cells of the olfactory bulbs, pyramidal cell layer CA 1 to CA3, and dentate gyrus of hippocampus formation and granular cell s of the cerebellum. Moreover, the activity was detected in the pontin e nuclei of brain stem. Olfactory bulbs, hippocampus, and cerebellum w ere believed to be bestowed high brain functions, i.e., long-term pote ntiation and long-term depression. A part of the function was regulate d by a retrograde neurotransmitter, nitric oxide ((NO)-N-.). Our findi ngs suggest that the SOD is colocalized with NO synthase in olfactory bulbs, hippocampus, and cerebellum, where (NO)-N-. plays the important roles. In contrast, low SOD activity was observed in the axonal neuro fiber bundles, although the regions contain a lot of membrane lipids, which was thought to be peroxidized by O-2(.-) and related radicals su ch as (OH)-O-. in the regions. From these findings, it was suggested t hat the SOD did not only play a role in protecting the neurons from en dogenously formed O-2(.-), but also play a role in preservation of ben eficial natures of (NO)-N-. in the brain. (C) 1998 Elsevier Science In c.