Effect of hyperbaric oxygen on striatal metabolites: a microdialysis studyin awake freely moving rats after MCA occlusion

We have shown that hyperbaric oxygen (HBO) reduced cerebral infarction in r at middle cerebral artery occlusion model (MCAO). The present study was und ertaken to evaluate the effect of HBO on ischemic striatal metabolites at d ifferent times after MCAO and reperfusion. A rat MCAO model was produced vi a the intraluminal filament method. After 2 h of occlusion the suture was r emoved and reperfusion was allowed. The rats were sacrificed at 24 h after reperfusion. HBO treatment was administered by putting rats in the HBO cham ber at 3 atmospheres absolute (ATA) HBO for I h. Glucose, lactate, pyruvate , and glutamate in striatal extracellular fluid were collected and measured by a microdialysis system at 7, 10, and 24 h after reperfusion. Glucose, p yruvate and glutamate concentrations were increased after reperfusion. HBO treatment decreased glucose, pyruvate, and glutamate almost to the control level (preocclusion level). The lactate concentration remained unchanged af ter ischemic/reperfusion and after HBO treatment. This study suggested that altered brain energy metabolites and excitatory amino acids occurred durin g cerebral ischemia and and HBO regulated these striatal metabolites, which might contribute to the protective effect of HBO in cerebral ischemia. (C) 2001 Elsevier Science B.V. All rights reserved.