Preconditioning with Ischemia and Intermittent Normobaric Hyperoxia Upregulate Glutamate Transporters and NF-kB activity in the Rat Brain
Trauma Monthly: 13 (1); 17-27 Article Type: Research Article
A. Preconditioning with Ischemia and Intermittent Normobaric Hyperoxia Upregulate Glutamate Transporters and NF-kB activity in the Rat Brain,
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Introduction: Recent studies suggest that intermittent and prolonged normobaric hyperoxia (HO) results in ischemic tolerance to reduce ischemia brain injury. In this research attempts were made to see the changes in excitatory amio-acid transporters (EAATs) and NF-kB activity following intermittent HO and ischemia preconditioning. Method: Rats were divided into two experimental groups, each of 21 animals. The first group was exposed to 95% inspired HO for 4h/day for 6 consecutive days (intermittent HO InHO). The second group acted as controls, and were exposed to 21% oxygen in the same chamber (normobaric normoxia or room air RA) continuously for six days (intermittent RA InRA). Each main group was subdivided to MCAO-operated (middle cerebral artery occlusion), sham-operated (without MCAO), and intact (without any surgery) subgroups. After 24h, MCAO-operated subgroups were subjected to 60min of right MCAO. After 24h reperfusion, neurologic deficit score (NDS) were assessed in MCAO-operated subgroups. Immediately and 48h after pretreatment, blood sampling for assessment of serum TNF-a levels were subjected. Then, the effect of intermittent HO and ischemia on NF-kB activity and EAATs expression were measured. Result: Preconditioning with intermittent HO and ischemia decreased NDS and upregulate EAAT1, EAAT2, and EAAT3 and increase NF-kB activity significantly. Conclusion: Although further studies are needed to clarify the mechanisms of ischemic tolerance, InHO and ischemia seems to partly exert their effects via increase upregulation of glutamate transporters and NF-kB activity.
normobaric hyperoxia; brain ischemia tolerance; stroke; neuroprotection; glutamate transporter; NF-kB activity
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