This study aimed to explore the effects of hyperbaric
oxygen (HBO2) on blood-brain barrier (BBB) integrity
in rats, when administered for one (at 2.5 ATA, 3 HBO2
sessions a day) and five days (at 2.5 ATA, 3 HBO2
sessions a day for the first two days, and twice a day
for the last three days). Horseradish peroxidase (HRP)
was used to evaluate the BBB permeability. Superoxide
dismutase (SOD) activity, glutathione (GSH) and
malondialdehyde (MDA) levels were measured in the
cerebral cortex and hippocampus regions. Frequent
vesicles containing HRP reaction products were observed
in capillary endothelial cells in the cerebral
cortex and hippocampus of rats subjected to HBO2.
The accumulation of HRP reaction products in these
brain regions was significantly higher than that of superoxide dismutase.
control animals (P<0.01). In animals that received HBO2,
MDA levels (P<0.01 for 5 days) and GSH (p<0.05 for one
day, and P<0.01 for five days) were decreased in the
cerebral cortex, whereas SOD activities slightly
increased in this region. In animals that received HBO2
significant decreases in MDA (P<0.05 for one day;
P<0.01 for five days) and GSH (P<0.05 for five days) levels
were observed in the hippocampus region, but SOD
activities decreased in this region.
We showed that HBO2 administered with the doses
described above impaired BBB integrity in otherwise
healthy rats. Therefore, we suggest that the results
of this study should be taken into consideration when
patients are exposed to HBO2 with the same doses.