Effect of Normobaric Oxygen Therapy in a Rat Model of Intracerebral Hemorrhage

Abstract

Background and Purpose— Normobaric oxygen (NBO) therapy may be neuroprotective in acute ischemic stroke. However, how NBO may affect intracerebral hemorrhage is unclear. We tested NBO in a rat model of striatal intracerebral hemorrhage. Methods— Intracerebral hemorrhage was induced by stereotactic injection of collagenase Type VII (0.5 U) into the right striatum of male Sprague-Dawley rats. One hour later, rats were randomized into controls (n=13) versus NBO treatment (n=13). NBO was applied for 2 hours. Hemorrhagic blood volume, brain water content, and neurological outcomes (forelimb placement test, forelimb asymmetry, neuroscore) were quantified at 72 hours. Experiments were repeated in a second independent laboratory to assess reproducibility in neurological outcomes (n=10 per group). Results— NBO did not worsen hemorrhage severity or brain edema. There were no significant differences in hemorrhagic blood volumes (control, 6.4±0.9 μL versus NBO, 7.0±2.1 μL; P =0.18) or brain water content (control, 81.9%±1.1% versus NBO, 81.6%±0.5%; P =0.58). NBO did not affect any of the neurological outcome tests in the primary or secondary studies. Conclusions— NBO therapy may not worsen outcomes in intracerebral hemorrhage.