Mild Hyperoxia Stimulation Increases Regional Tissue Oxygen Pressure in Rat Hippocampus via Oxygen Radical

Aims: The purpose of this study is to examine a rise of the local tissue oxygen pressure in hippocampus (Hip-pO2) which means neuronal activation by mild hyperoxia through oxygen radical.

Study Design: Study was an animal experiment with rat.

Place and Duration of Study: Department of Department of Life Science and Applied Chemistry, Nagaya Institute of Technology, between January 2014 and January 2018.

Methodology: Rats were exposed to air or mild oxygen gas. At the same time, Local tissue oxygen pressure in hippocampus (Hip-pO2) were measured for 20 min with or without treatment of two type of radical scavengers.

Results: The Hip-pO2 levels were significantly increased by mild hyperoxia exposure (50-60% above resting level). The mild hyperoxia-induced enhancement of the Hip-pO2 levels were inhibited by MnTMPyP (radical scavenger), but not by NADPH oxidase (NOX) inhibitor Apocynin.

Conclusion: These findings suggested that mild hyperoxia could activate hippocampus through generation of oxygen radicals.