Cortical spreading depression affects reactive oxygen species production

Cortical spreading depression (CSD) is a reversible electrophysiological phenomenon that is not associated with tissue damage under normal blood supply. The induction of CSD during ischemia causes an increase in tissue damage, while pre-conditioning with CSD decreases the damage induced by a subsequent episode of ischemia. The mechanisms underlying these effects are not clear. Because the production of reactive oxygen species (ROS) is involved in tissue damage during ischemia-reperfusion, the aim of the present study was to evaluate the effects of CSD on superoxide production (O-2(-)), on hydrogen peroxide (H2O2) production and on superoxide dismutase (SOD) activity in the cerebral cortex. CSD was induced by KCl application on the cortical surface in rats. O-2(-) production was evaluated using dihydroethidium (DHE) that is oxidized to the fluorescent dye ethidium (HEt) by O-2(-). The extracellular level of H2O2 was evaluated by microdialysis sampling and HPLC analysis. SOD activity was evaluated with a histochemical assay. The results showed an increase in H2O2 production, an increase in SOD activity and a decrease in O-2(-) concentration 1 h after CSD induction. (C) 2010 Published by Elsevier B.V.