Experimental study on normobaric hyperoxia effect for ischemic brain edema

Objective To explore the effect of normobaric hyperoxia on brain edema following acute ischemic stroke. Methods We chose male sprague dawley rats. They were randomly divided into three groups, including the sham group, the model group and oxygen-inspiration group. And then each group was randomly divided into five subgroups which were reperfusion for 0.5, 3.0, 6.0, 12.0 and 24.0 h. We used the middle cerebral artery ischemic reperfusion model referring to Zea Longa suture method. The quantitative polymerase chain reaction (PCR) was used to detect the expression of aquaporin 4 (AQP4) mRNA. Results The AQP4 mRNA expression levels of the ischemic brain tissue in rats were significantly increased in the model group (4.808±1.091) and oxygen-inspiration group (4.268±1.032) relative to the sham group (1.003±0.003) at each time point (P=0.000). Also, the mRNA expression levels of AQP4 were significantly lower in oxygen-inspiration group than the model group at 3 h (P=0.011), 6 h (P=0.008), 12 h (P=0.019) and 24 h (P=0.014). Conclusion 61% NBO can inhibit the expression of AQP4 mRNA and reduce the brain edema in acute ischemic reperfusion model rats. Key words: Normobaric hyperoxia; Brain edema; Aquaporin 4; Rats