RESUMEN
Objective To investigate changes in the expression of apurinic/apyrimidinic endonuclease (APE) and the oxidative DNA damage marker 8 OHdG in distant hippocampus regions of the rat brain after focal cerebral ischemia of the middle cerebral artery.Methods SD rats were divided into the sham surgery group and the pMCAO group (induced by middle cerebral artery occlusion).Pathological changes in brain tissues were examined at 2 h,6 h,12 h,24 h,48 h and 72 h.The expression of APE and 8-OHdG was measured by immunohistochemical staining methods.TUNEL staining was performed to detect apoptosis.Results Reduction of APE expression in the CA1 region of the hippocampus on the ischemia side appeared at 2 h in the pMCAO group and continued as ischemia persisted (F=11.91,P＜0.05).The expression of 8OHdG and TUNEL immunoreactivity in the CA1 region of the hippocampus on the ischemia side were first observed at 6h in the pMCAO group and intensified during the remainder of induced ischemia (F=9.23 and 10.46 respectively,P＜0.05 for both).Compared with the sham group,8-OHdG expression and TUNEL immunoreactivity in the pMCAO group were at nearly the same levels from 24 h to 72h.Conclusions Oxidative DNA damage occurs in hippocampus regions of the rat brain after experimentally induced focal cerebral ischemia of the middle cerebral artery.APE expression declines in regions distant from focal cerebral ischemia.Development and accumulation of oxidative DNA damage can induce apoptosis in certain brain regions.