Antioxidants attenuate reperfusion injury after global brain ischemia through inhibiting nuclear factor-kappa B activity in rats

摘要

AIM: To investigate the effects of two antioxidants on the alterations of nuclear factor kappaB (NF-κB) activity and p65, p50 protein expression and phosphorylation of IκBα in rat hippocampus following global brain ischemia. METHODS: Using a 4-vessel occlusion (4-VO) as brain ischemia model, NF-κB protein (p65 or p50 subunit) expression was examined by Western blot analysis, and NF-κB activity was assayed by electrophoretic mobility shift assay (EMSA), and neuronal loss was observed by histology. RESULTS: NF-κB activity displayed a time-dependent manner, and p65, p50 proteins showed their peak levels after ischemia/reperfusion 6 h. NF-κB inductions (p65: 4.79+-0.78, p50: 5.50+-0.33, sham control=1) and activity (4.93+-0.95) after 6 h of reperfusion were markedly reduced by pretreatment with antioxidants pyrrolidine dithiocarbamate (PDTC, 200 mg/kg) (p65: 1.11+-0.74, p50: 1.38+-0.98, activity: 2.20+-0.86, respectively) or N-acetylcysteine (NAC, 300 mg/kg) (p65: 0.64+-0.39, p50: 1.89+-0.87, activity: 0.61+-0.65), and histological observations of the pyramidal layer of CA1 also showed a reduction of neuronal loss in rat hippocampus (70%+-5% or 92%+-4% cells are survival, respectively). Furthermore, PDTC and NAC prevented the decrease (from 0.50+-0.10 to 0.80+-0.20 or 1.20+-0.24, respectively) and phosphorylation (from 2.00+-0.15 to 0.46+-0.10 or 0.41+-0.10, respectively) of IκBα protein in the cytoplasm. CONCLUSION: The protective effects of antioxidants against ischemia/reperfusion-induced injury may be mediated by down-regulation of NF-κB activity. NF-κB activation and deactivation are controlled mainly through phosphorylation and degradation of IκBκα following brain ischemia.