Frontiers in Aging Neuroscience · Mar 4, 2026

Effect of inspired oxygen fraction during anesthesia on inflammation and antioxidant enzyme activity in the mouse cortex and hippocampus

By Chang JE, Lee EH, Oh SJ et al.

INTRODUCTION: Although high inspired oxygen fraction (FiO₂) is used during anesthesia to prevent hypoxemia, the effect of different oxygen fraction on the brain remains unclear. This study aims to evaluate whether different inspired oxygen fractions (FiO₂ 30% vs. 80%) during anesthesia affect inflammation and antioxidant enzyme activity in the cortex and hippocampus of young and aged mice. METHODS: Young and old mice were anesthetized with sevoflurane at FiO₂ 30% or 80% for 3 h. Mice in the control group were exposed to medical air (FiO₂ 21%) for 3 h. Cytokine and superoxide dismutase (SOD) assays were performed on the cortex and hippocampus samples after anesthesia. RESULTS: The IL-1β level in the hippocampus was significantly higher in the FiO₂ 80% group compared with controls [5.0 (4.0-6.9) pg. mL⁻¹ vs. 2.3 (1.6-2.7) pg. mL⁻¹; adjusted p = 0.032], whereas no significant differences were observed in IL-1β levels between the control and FiO₂ 30% groups [adjusted p = 0.164] or the FiO₂ 30% and FiO₂ 80% groups [adjusted p = 0.390]. Except for IL-1β in the hippocampus, no significant differences in the cytokine levels and SOD activities were observed among the groups according to the inspired oxygen fraction in either brain region or age group [p > 0.05]. DISCUSSION: Only 80% oxygen increased hippocampal IL-1β compared with controls, suggesting region-specific vulnerability to oxygen-induced neuroinflammation. However, no significant differences between FiO₂ levels (30% vs. 80%) indicate a limited neuroinflammatory impact under 3 h of anesthesia. Further studies with longer exposure and surgical conditions are needed to clarify the clinical implications.

doi.org/10.3389/fnagi.2026.1761281Open accessPubMed 41858786Mechanisms