Novel Approach in Modulating Pyruvate Dehydrogenase Complex After

Stroke is one of the most debilitating vascular diseases worldwide, which is keeping our healthcare costs as high as $38.6 billion each year. Systemic thrombolysis with intravenous tissue-type plasminogen activator and in situ clot retrieval remain the only reperfusion strategies approved by the Food and Drug Administration. However, after nearly 2 decades of tissue-type plasminogen activator use in the United States, most patients with acute ischemic stroke have not benefited from a reperfusion strategy, with <10% of patients actually receiving systemic thrombolysis. This is attributed to tissue-type plasminogen activator’s contraindications, and most importantly, its narrow therapeutic time window. Furthermore, while a small portion of patients (17%) undergo spontaneous lysis by 6 to 8 hours, many patients experience permanent artery occlusion. In addition, even if recanalization is successful, outcome is often poor because of reperfusion injury. Although energy failure and oxidative stress with reactive oxygen species (ROS) generation after ischemia are well-documented pathophysiologies of neural injury, recent research has failed to develop targeted therapies to address Background and Purpose—Ischemic stroke induces metabolic disarray. A central regulatory site, pyruvate dehydrogeanse complex (PDHC) sits at the cross-roads of 2 fundamental metabolic pathways: aerobic and anaerobic. In this study, we combined ethanol (EtOH) and normobaric oxygen (NBO) to develop a novel treatment to modulate PDHC and its regulatory proteins, namely pyruvate dehydrogenase phosphatase and pyruvate dehydrogenase kinase, leading to improved metabolism and reduced oxidative damage. Methods—Sprague–Dawley rats were subjected to transient (2, 3, or 4 hours) middle cerebral artery occlusion followed by 3or 24-hour reperfusion, or permanent (28 hours) middle cerebral artery occlusion without reperfusion. At 2 hours after the onset of ischemia, rats received either an intraperitoneal injection of saline, 1 dose of EtOH (1.5 g/kg) for 2and 3-hour middle cerebral artery occlusion, 2 doses of EtOH (1.5 g/kg followed by 1.0 g/kg in 2 hours) in 4 hours or permanent middle cerebral artery occlusion, and EtOH+95% NBO (at 2 hours after the onset of ischemia for 6 hours) in permanent stroke. Infarct volumes and neurological deficits were examined. Oxidative metabolism and stress were determined by measuring ADP/ATP ratio and reactive oxygen species levels. Protein levels of PDHC, pyruvate dehydrogenase kinase, and pyruvate dehydrogenase phosphatase were assessed. Results—EtOH induced dose-dependent neuroprotection in transient ischemia. Compared to EtOH or NBO alone, NBO+EtOH produced the best outcomes in permanent ischemia. These therapies improved brain oxidative metabolism by decreasing ADP/ATP ratios and reactive oxygen species levels, in association with significantly raised levels of PDHC and pyruvate dehydrogenase phosphatase, as well as decreased pyruvate dehydrogenase kinase. Conclusions—Both EtOH and EtOH+NBO treatments conferred neuroprotection in severe stroke by affecting brain metabolism. The treatment may modulate the damaging cascade of metabolic events by bringing the PDHC activity back to normal metabolic levels. (Stroke. 2015;46:492-499. DOI: 10.1161/STROKEAHA.114.006994.)