Neuroprotection conferred by post-ischemia ethanol therapy in experimental stroke: an inhibitory effect on hyperglycolysis and NADPH oxidase activation

Ethanol provides neuroprotection following ischemia/reperfusion. This study assessed ethanol's effect on hyperglycolysis and NADPH oxidase (NOX) activation. Adult, male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2h. Three sets of experiments were conducted to determine ethanol's effect on (i) conferring neuroprotection by measuring infarct volume and neurological deficits 24h post reperfusion; (ii) cerebral glucose metabolism and lactic acidosis by measuring brain and blood glucose concentrations and protein expression of glucose transporter 1 and 3 (GLUT1, GLUT3), phosphofructokinase (PFK), as well as lactic acidosis by measuring lactate dehydrogenase (LDH), and lactate; and (iii) nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activation by detecting enzymatic activity and subunit expression at 3h after reperfusion. When administered upon reperfusion, ethanol (1.5g/kg) reduced infarct volume by 40% (p<0.01) and neurological deficits by 48% at 24h post reperfusion while reducing (p<0.01) elevations in glycolytic protein expression and lactate levels during early reperfusion (3h). Ethanol increased the reductions in cerebral glucose concentration at 3h post reperfusion by 64% (p<0.01) while enhancing (p<0.01) post stroke blood glucose concentration, suggesting a reduced cellular glucose uptake and utilization. Ethanol decreased (p<0.01) stroke-induced NOX activation by reducing enzymatic activity and gp91phox expression by 45% and 38%, respectively. Post-ischemia ethanol treatment exerts neuroprotection through attenuation of hyperglycolysis and associated NOX activation. Because of the lack of associated hypoglycemia and selectivity toward decreasing cerebral metabolism, further investigation of ethanol's use as a post-stroke therapy, especially in the context of hyperglycemia, seems warranted.