Impact of reoxygenation with oxygen and air on the extent of the brain damage after hypoxia-ischaemia in neonatal rats.

Brain damage after hypoxia-ischaemia develops partly during the state of reoxygenation. The generation of free oxygen radicals is considered to be one possible mechanism. In order to evaluate the role of hyperoxygenation, a comparison was made between reoxygenation with pure oxygen and with air after hypoxia-ischaemia in a rat model of unilateral cerebral hemisphere damage. Brain damage was induced in 7-day-old rats. The animals were treated during reoxygenation with either 100% oxygen for 0.5 h or air. The extent of the brain damage was determined at 3 weeks of age by weighing the left and right hemispheres separately. No significant difference in weight deficit of the hemispheres was seen in the oxygen-treated group (15.5%, median) compared to the air-treated group (25.0%). Reoxygenation with pure oxygen after hypoxia-ischaemia in neonatal rats does not cause increased brain damage compared with reoxygenation with room air.