Moderate hypothermia suppresses jugular venous superoxide anion radical, oxidative stress, early inflammation, and endothelial injury in forebrain ischemia/reperfusion rats

The aim of this study was to assess the effect of moderate hypothermia (MH) on generation of jugular venous superoxide radical (O2−·), oxidative stress, early inflammation, and endothelial injury in forebrain ischemia/reperfusion (FBI/R) rats. Twenty-one Wistar rats were allocated to a control group (n = 7, 37 °C), a pre-MH group (n =   7, 32 °C before ischemia), and a post-MH group (n =   7, 32 °C after reperfusion). MH was induced before induction of ischemia in the pre-MH group and just after reperfusion in the post-MH group. Forebrain ischemia was induced by occlusion of bilateral common carotid arteries with hemorrhagic hypotension for 10 min, followed by reperfusion. O2−· in the jugular vein was measured from the produced current using a novel O2−· sensor. The O2−· current showed a gradual increase during forebrain ischemia in the control and post-MH groups but was attenuated in the pre-MH group. Following reperfusion, the current showed a marked increase in the control group but was strongly attenuated in the pre- and post-MH groups. Concentrations of malondialdehyde, high-mobility group box 1 (HMGB1) protein, and intercellular adhesion molecule-1 (ICAM-1) in the brain and plasma 120 min after reperfusion in the pre- and post-MH groups were significantly lower than those in the control group, except for plasma HMGB1 in the post-MH group. In conclusion, MH suppressed O2−· measured in the jugular vein, oxidative stress, early inflammation, and endothelial injury in FBI/R rats.