The Effects of Xanthine Oxidoreductase Inhibitors on Oxidative Stress Markers following Global Brain Ischemia Reperfusion Injury in C57BL/6 Mice

We demonstrated that 3-nitrotyrosine and 4-hydroxy-2-nonenal levels in mouse brain were elevated from 1 h until 8 h after global brain ischemia for 14 min induced with the 3-vessel occlusion model; this result indicates that ischemia reperfusion injury generated oxidative stress. Reactive oxygen species production was observed not only in the hippocampal region, but also in the cortical region. We further evaluated the neuroprotective effect of xanthine oxidoreductase inhibitors in the mouse 3-vessel occlusion model by analyzing changes in the expression of genes regulated by the transcription factor nuclear factor-kappa B (including pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 and intercellular adhesion molecules-1). Administration of allopurinol resulted in a statistically significant decrease in IL-1β and TNF-α mRNA expression, whereas febuxostat had no significant effect on expression of these genes; nevertheless, both inhibitors effectively reduced serum uric acid concentration. It is suggested that the neuroprotective effect of allopurinol is derived not from inhibition of reactive oxygen species production by xanthine oxidoreductase, but rather from a direct free-radical-scavenging effect.