^aDepartment of Neurology, Changhai Hospital,174 Changhai Road, Shanghai 200433, PR China

^bDepartment of Diving Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai, 200433, PR China

^cDepartment of Neurosurgery, Loma Linda University, Loma Linda, California, USA

Abstract

The present study examined the hypothesis that cerebral ischemic tolerance induced by hyperbaric oxygen preconditioning (HBO-PC) is associated with an increase of antioxidant enzyme activity. Male Sprague–Dawley rats (250–280 g, n = 74) were divided into sham, middle cerebral artery occlusion (MCAO) for 90 min, and MCAO plus HBO-PC groups. HBO-PC was conducted four times by given 100% oxygen at 2.5 atmosphere absolute (ATA), for 1 h at every 12 h interval for 2 days. At 24 h after the last HBO-PC, MCAO was performed and at 24 h after MCAO, neurological function and Nissl Staining were performed to evaluate the effect of HBO-PC. Malondialdehyde (MDA) content, activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) sampled from the hippocampus, ischemic penumbra or core of cortex were measured. HBO-PC decreased mortality rate, improved neurological recovery, lessened neuronal injury, reduced the level of MDA and increased the antioxidant activity of CAT and SOD. These observations demonstrated that an upregulation of the antioxidant enzyme activity by HBO preconditioning plays an important role in the generation of tolerance against brain ischemia–reperfusion injury.

Keywords: Hyperbaric oxygen; Prevention; Antioxidant enzyme; Ischemic tolerance; Reactive oxygen species

Article Outline

1. Introduction

2. Results

2.1. Physiologic variables

2.2. Mortality rate and neurologic outcome

2.3. Nissl staining

2.4. MDA content

2.5. Antioxidant enzyme activities

3. Discussion

4. Experimental procedures

4.1. Animals and groups

4.2. HBO preconditioning

4.3. MCAO procedures

4.4. Neurologic functional scoring

4.5. Nissl staining

4.6. Ischemic core and penumbra dissections

4.7. Measurement of antioxidant enzyme activity and malondialdehyde content

4.8. Statistical analyses

Acknowledgements

Glossary

References