Time course of neuroprotection induced by normobaric hyperoxia and NCX1 expression.
BACKGROUND
The purpose of this study was to determine if normobaric hyperoxia (HO) pre-conditioning offers durable neuroprotection against cerebral ischaemia and its effects on NCX1 expression.


METHODS
Rats were divided into two experimental groups. The first group was exposed to 95% inspired HO for 4 hours/day for 6 consecutive days (HO). The second group acted as control and was exposed to 21% oxygen in the same chamber. Each main group was sub-divided to middle cerebral artery occlusion (MCAO-operated) and intact (without any surgery) sub-groups. After 2, 5, 10 and 15 days from pre-treatment, MCAO-operated sub-groups were subjected to 60 minutes of right MCAO. After 24 hours reperfusion, neurologic deficit score and infarct volume were measured in MCAO-operated sub-groups. The NCX1 expression levels of core, penumbra and sub-cortex regions were assessed in sham-operated and intact sub-groups.


RESULTS
Pre-conditioning with HO decreased neurologic deficit score and infarct volume, and increased expression of NCX1 in penumbra and sub-cortex. These effects of hyperoxia disappeared gradually during 15 days after pre-treatment.


CONCLUSIONS
Although further studies are needed to clarify the mechanisms of time course of neuroprotection, HO partly is associated with expression of NCX1 consistent with an active role in the genesis of ischaemic neuroprotection.
Department of Physiology, Faculty of Biological Sciences, Shaheid Beheshti University , G.C., Tehran , Iran.
Ekram
E
Mohammadi
Mohammad Reza
MR
Bigdeli
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D018496:Hyperoxia; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D018696:Neuroprotective Agents / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*
D018696:Neuroprotective Agents; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1
Brain ischaemia tolerance; NCX1; neuroprotection; normobaric hyperoxia; reactive oxygen speciestime course; stroke