Oxidative Cellular Damage and the Reduction of APE/Ref-1 Expression after Experimental Traumatic Brain Injury

Oxidative Cellular Damage and the Reduction of APE/Ref-1 Expression after Experimental Traumatic Brain Injury

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The DNA repair enzyme, apurinic/apyrimidinic endonuclease (or redox effector factor-1, APE/Ref-1), is involved in base excision repair of apurinic/apyrimidinic sites after oxidative DNA damage.We investigated the expression of APE/Ref-1 and its relationship to oxidative stress after severe traumatic brain injury produced by controlled cortical impact in normal mice, and in mice over- or underexpressing copper-zinc superoxide dismutase 2.75x100 (SOD1TG and SOD1KO, respectively).Oxygen free radical-mediated cellular injury was visualized with 8-hydroxyguanine immunoreactivity as a marker for DNA oxidation, and in situ hydroethidine oxidation as a marker for superoxide production.After trauma there was a reduced expression of APE/Ref-1 in the ipsilateral cortex and hippocampus that correlated with the gene dosage levels of cytosolic superoxide dismutase.The decrease in APE/Ref-1 expression preceded DNA fragmentation.

There was also a close correlation between APE/Ref-1 protein levels 4 h after trauma and the volume of jordan 5 space jam for sale the lesion 1 week after injury.Our data have demonstrated that reduction of APE/Ref-1 protein levels correlates closely with the level of oxidative stress after traumatic brain injury.We suggest that APE/Ref-1 immunoreactivity is a sensitive marker for oxidative cellular injury.