Hyperbaric oxygen therapy for five days increases blood-brain barrier permeability

Area of Science:

• Neuroscience
• Biomedical Engineering
• Pharmacology

Background:

• The blood-brain barrier (BBB) protects the central nervous system but can be compromised in various conditions.
• Hyperbaric oxygen therapy (HBO₂) involves breathing pure oxygen at increased atmospheric pressure, with potential therapeutic applications but also risks.
• Understanding HBO₂ effects on BBB integrity is crucial for patient safety and treatment optimization.

Purpose of the Study:

• To investigate the impact of specific hyperbaric oxygen (HBO₂) regimens on blood-brain barrier (BBB) integrity in a rat model.
• To assess changes in BBB permeability and oxidative stress markers in response to HBO₂ exposure.

Main Methods:

• Rats were exposed to HBO₂ at 2.5 ATA for one or five days, with varying daily session counts.
• Blood-brain barrier permeability was evaluated using horseradish peroxidase (HRP) extravasation.
• Oxidative stress markers, including superoxide dismutase (SOD) activity, glutathione (GSH), and malondialdehyde (MDA) levels, were measured in the cerebral cortex and hippocampus.

Main Results:

• HBO₂ administration led to increased HRP accumulation in the cerebral cortex and hippocampus, indicating compromised BBB integrity.
• Significant alterations in oxidative stress markers were observed: decreased MDA and GSH levels in both brain regions, and altered SOD activity.
• These changes were dose- and duration-dependent, with more pronounced effects after five days of HBO₂ treatment.

Conclusions:

• The studied HBO₂ regimens, particularly the five-day protocol, significantly impaired blood-brain barrier integrity in healthy rats.
• The observed biochemical changes suggest HBO₂ can induce oxidative stress within the brain tissue.
• These findings highlight the importance of considering potential BBB disruption when administering HBO₂ at the described doses, especially in patient populations.