Effect of intermittent normobaric hyperoxia on bloodbrain barrier in a rat model of stroke

  Background: Recent studies have shown that the use of prolonged or intermittent normobaric hyperoxia (90 percent) can decrease brain damages caused by stroke.   Objective: The aim of this study was to investigate the effects of oxygen radicals in potentiating the blood-brain barrier caused by normobaric hyperoxia in a rat model of stroke.   Methods: This was a experimental study performed in spring 2010. A total of 42 male Wistar rats (250-350 g) were initially divided into two main groups. Both group were exposed to normobaric hyperoxia (90 percent HO) and room air (21 percent RA) 4 h/day for 6 days. Later, each main group was subdivided into three subgroups to receive dimethyltiourea. After 24 h, the neurologic deficit scores and blood-brain barrier permeability were assessed. Data were analyzed by one way ANOVA and Mann Whitney U tests.   Findings: The medians of neurologic deficit scores and blood-brain barrier permeability decreased in RA and HO (P=0.02). The neurologic deficit score and the reduced brain edema were significantly relived by MT (P=0.43).   Conclusion: The blood-brain impermeability caused by intermittent normobaric hyperoxia was relieved by use of oxygen radical scavengers.