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Updated: Jun 19, 2026
Quantification of Neurovascular Protection Following Repetitive Hypoxic Preconditioning and Transient Middle Cerebral Artery Occlusion in Mice
Published on: May 4, 2015
Reduced matrix metalloproteinase-9 activity and cell death after global ischemia in the brain preconditioned with
Robert P Ostrowski1, Vikram Jadhav, Wanqiu Chen
1Department of Physiology and Pharmacology, Linda University School of Medicine, Loma Linda, CA 92350, USA.
Abstract:
Matrix metalloproteinase-9 (MMP-9) plays a deleterious role in cell death after global cerebral ischemia. Preconditioning with hyperbaric oxygen (HBO-PC) reduces neuronal damage in the post-ischemic brain; however, its effect on ischemia-induced increase in MMP-9 activity and expression remains unexplored.We investigated effects of HBO-PC on alterations in MMP-9 activity/tissue expression accompanying neuronal death after transient global cerebral ischemia.Male SD rats (300-350 g), were allocated either to non-ischemic (naive control or sham-operated) or ischemic (four-vessel occlusion, 4VO; 10 min) groups that were HBO-preconditioned (2.5 ATA, 1 h daily for 5 days; the last session 24 h before ischemia) or not. Neurobehavioral deficits were assessed prior to collection of brain tissue for gel zymography (MMP-9) and histology (MMP-9 immunofluorescence, TUNEL) at 0 (without ischemia), 6, 24, 72 h and 7 days after 4VO.Both, MMP-9 levels and cell death increased in the hippocampus at 72 h after 4VO. HBO-PC suppressed postischemic MMP-9 activity and CA1 cell damage, and improved functional performance. The increase in MMP-9 immunoreactivity in the brain was also detected after HBO-PC alone. HBO-PC suppresses MMP-9 activity and expression in the postischemic hippocampus. The mechanism of HBO preconditioning may depend on the induction of MMP-9 in the preischemic phase and may be in part mediated by exhaustion of MMP-9 stores in cerebral tissues.
Insights
Hyperbaric oxygen preconditioning (HBO-PC) reduces neuronal death after cerebral ischemia by suppressing matrix metalloproteinase-9 (MMP-9) activity and expression. This neuroprotective effect may involve MMP-9 induction during preconditioning.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Matrix metalloproteinase-9 (MMP-9) exacerbates neuronal damage following global cerebral ischemia.
- Hyperbaric oxygen preconditioning (HBO-PC) is known to reduce brain injury post-ischemia.
- The specific impact of HBO-PC on MMP-9 activity and expression after ischemia is not well understood.
Purpose of the Study:
- To investigate the effects of HBO-PC on MMP-9 activity and expression in the context of neuronal death after transient global cerebral ischemia.
- To determine if HBO-PC can mitigate ischemia-induced increases in MMP-9 and subsequent neuronal damage.
Main Methods:
- Male Sprague-Dawley rats underwent transient global cerebral ischemia (10 min four-vessel occlusion).
- Animals were either HBO-preconditioned (2.5 ATA for 5 days) or not.
- MMP-9 activity (gel zymography), expression (immunofluorescence), cell death (TUNEL), and neurobehavioral deficits were assessed at various time points post-ischemia.
Main Results:
- Global cerebral ischemia led to increased MMP-9 levels and hippocampal cell death 72 hours post-injury.
- HBO-PC significantly suppressed post-ischemic MMP-9 activity and CA1 neuronal damage.
- HBO-PC also improved neurobehavioral outcomes, and increased MMP-9 immunoreactivity was observed even with HBO-PC alone.
Conclusions:
- HBO-PC effectively suppresses MMP-9 activity and expression in the post-ischemic hippocampus.
- The neuroprotective mechanism of HBO-PC may involve the induction of MMP-9 during the preconditioning phase, potentially leading to the exhaustion of MMP-9 stores.
