Abstract WP272: A Powerful Combination Therapy for Stroke: Post-Ischemia Ethanol Administration and Normobaric Oxygenation on Ischemic Rats

Abstract

Objectives: Normobaric oxygenation (NBO) has been reported to be neuroprotective against acute cerebral ischemia. Recently, a clinical trial was terminated because beneficial outcomes were not definitive. Our recent study ( Stroke. 2012 43(1):205-10 ) demonstrated a strong neuroprotective effect induced by acute administration of ethanol (EtOH) at 1.5g/kg. In this study, we assessed the therapeutic influence of EtOH in combination with NBO. Methods: Sprague-Dawley rats were subjected to right middle cerebral artery occlusion for 2h. Ischemic animals received either an intraperitoneal injection of EtOH (1.0g/kg), a course of NBO (100% for 2h), or a combination of both immediately prior to reperfusion onset. Brain injury was determined by infarct volume and behavioral outcomes at 48h post-reperfusion. Metabolic dysfunction was investigated by assessing ADP/ATP ratios, reactive oxygen species (ROS) levels, NADPH oxidase (NOX) activity, and protein expression of NOX subunits (p47 phox , gp91 phox , and p67 phox ), as well as the protein expression and enzyme activity of pyruvate dehydrogenase (PDH), at both 3h and 24h after reperfusion. Results: Combination therapy led to a significant decrease in infarct volumes (Saline: 48±4%, EtOH: 38±3%, NBO: 37±4%, Combination: 19±3% ) and in neurological deficits (Belayev Scale 0-12, Saline: 8.4±0.7; EtOH: 6.5±0.7; NBO: 6.4±0.6; Combination: 4.4±0.3 ). At 3h and 24h post-reperfusion the decrease in ADP/ATP ratio was significantly enhanced, reflecting a preservation of cellular energy. A greater decrease in NOX activity and protein expression was observed, in association with decreased ROS levels, suggesting that improved glycolysis may contribute to neuroprotection. PDH activity and protein expression was dramatically increased, making the facilitation of aerobic metabolism a probable mechanism for preserving cellular ATP. Conclusions: Our findings demonstrate that a synergistic relationship exists between EtOH and NBO. Both are promising neuroprotective agents when used together, even at low doses. Moreover, both are inexpensive, widely available, easy to administer, and have little side effects. Thus, combination therapy could be an effective and efficient approach to future stroke treatments.