Normobaric hyperoxia induces ischemic tolerance and upregulation of glutamate transporters in the rat brain and serum TNF-alpha level.
Recent studies suggest that intermittent and prolonged normobaric hyperoxia (HO) results in ischemic tolerance to reduce ischemic brain injury. In this research, we attempted to see changes in excitatory amino acid transporters (EAATs) and TNF-alpha levels following prolonged and intermittent hyperoxia preconditioning. Rats were divided into four experimental groups, each of 21 animals. The first two were exposed to 95% inspired HO for 4 h/day for 6 consecutive days (intermittent HO, InHO) or for 24 continuous hours (prolonged HO, PrHO). The second two groups acted as controls, and were exposed to 21% oxygen in the same chamber. Each main group was subdivided to middle cerebral artery occlusion (MCAO-operated), sham-operated (without MCAO), and intact (without any surgery) subgroups. After 24 h from pretreatment, MCAO-operated subgroups were subjected to 60 min of right MCAO. After 24 h reperfusion, neurologic deficit score (NDS) and infarct volume were measured in MCAO-operated subgroups. EAATs expression and serum TNF-alpha levels were assessed in sham-operated and intact subgroups. Preconditioning with prolonged and intermittent HO decreased NDS and upregulated EAAT1, EAAT2, and EAAT3 and increased serum TNF-alpha levels significantly. Although further studies are needed to clarify the mechanisms of ischemic tolerance, the intermittent and prolonged HO seems to partly exert their effects via increase serum TNF-alpha levels and upregulation of EAATs.
Faculty of Biological Sciences, Shahid Beheshti University, G.C., Tehran, Iran.
Mohammad Reza
MR
Bigdeli
Sohrab
S
Hajizadeh
Mehdi
M
Froozandeh
Ali
A
Heidarianpour
Bahram
B
Rasoulian
Ali Reza
AR
Asgari
Khalil
K
Pourkhalili
Ali
A
Khoshbaten
D000818:Animals; D001921:Brain / Q000378:metabolism*; D020520:Brain Infarction / Q000209:etiology / Q000473:pathology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D027342:Excitatory Amino Acid Transporter 2 / Q000378:metabolism*; D018496:Hyperoxia; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology; D019194:Ischemic Preconditioning; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*; D015854:Up-Regulation / Q000502:physiology*
D027342:Excitatory Amino Acid Transporter 2; D014409:Tumor Necrosis Factor-alpha