Therapeutic effect of tPA in ischemic stroke is enhanced by its combination with normobaric oxygen and hypothermia or ethanol

Background and Purpose: Our lab has previously elucidated the neuroprotective effects of normobaric oxygen (NBO) and ethanol (EtOH) in ischemic stroke. The present study further evaluated the effect of EtOH or hypothermia (Hypo) in the presence of low concentration of NBO and determined whether EtOH can substitute hypothermia in a more clinically relevant autologous embolus rat stroke model in which reperfusion was established by tissue-type plasminogen activator (t-PA). Methods: At 1 h of middle cerebral artery occlusion (MCAO) by an autologous embolus, rats received t-PA. In addition, at the same time, ischemic animals were treated with either EtOH (1.0 g/kg) or hypothermia (33 degrees C for 3 h) in combination with NBO (60% for 3 h). Extent of neuroprotection was assessed by apoptotic cell death measured by ELISA and Western immunoblotting analysis for pro- (AIF, activated Caspase-3, Bax) and anti-apoptotic (Bcl-2) protein expression at 3 and 24 h of reperfusion induced by t-PA administration. Results: Compared to ischemic rats treated only with t-PA, animals with NBO, hypothermia or EtOH had significantly reduced apoptotic cell death by 32.5%, 43.1% and 36.0% respectively. Furthermore, combination therapy that included NBO+EtOH or NBO+Hypo with t-PA exhibited a much larger decline (p < 0.01) in the cell death by 71.1% and 73.6%, respectively. Similarly, NBO+EtOH or NBO+Hypo treatment in addition to t-PA enhanced beneficial effects on both pro- and antiapoptotic protein expressions as compared to other options. Conclusions: Neuroprotection after stroke can be enhanced by combination treatment with either EtOH or hypothermia in the presence of t-PA and 60% NBO. Because the effects produced by EtOH and hypothermia are comparable, their mechanism of action may be not only similar but also could be interchangeable in future clinical trials. (C) 2015 Published by Elsevier B.V.