Neuroprotection by hyperbaric oxygenation after experimental focal cerebral ischemia monitored by MRI.
BACKGROUND
Hyperbaric oxygenation (HBO) after focal cerebral ischemia reduces infarct size and improves outcome when applied early after stroke. Here, we evaluated effects of HBO on permanent focal cerebral ischemia and applied magnetic resonance imaging (MRI) monitoring to study lesion evolution.


METHODS
Rats underwent permanent middle cerebral artery occlusion (MCAO). Two hours later, animals were treated with HBO (100% O(2)/2 atm; n=17) for 1 hour or treated with room air (n=17). Animals underwent serial MRI studies (DWI, PI, T2) beginning 90 minutes after MCAO. Neuroscore was assessed (5-point rating scale). Animals were euthanized and brains were 2,3,5-triphenyltetrazolium chloride (TTC)-stained for infarct volume calculation 120 hours after MCAO. Immunohistochemistry was performed with antibodies against c-FOS and 4-hydroxy-2-nonenal-modified proteins (HNE) to check for effects of oxidative stress caused by HBO treatment.


RESULTS
HBO reduced infarct volume by 38% (P<0.001). As shown by MRI, neuroprotection began 5 hours after ischemia and remained effective for 5 days. The relative regional cerebral blood flow was not different between groups at 3.5 and 5 hours after occlusion. There was less neurological deficit in HBO-treated animals compared with controls (P<0.05). Lipid peroxidation of cerebral vessels after HBO treatment as measured by HNE staining and pattern of c-FOS induction were not significantly different between groups at 3.5 and 8 hours after ischemia.


CONCLUSIONS
As monitored by MRI HBO treatment reversed ischemic lesion size between 3 and 5 hours after ischemia and achieved a long-lasting neuroprotective effect without significant oxidative damage.
Schäbitz
Wolf-Ruediger
WR
Department of Neurology , University of Heidelberg, Germany.
Schade
Holger
H
Heiland
Sabine
S
Kollmar
Rainer
R
Bardutzky
Jürgen
J
Henninger
Nils
N
Müller
Harald
H
Carl
Ulrich
U
Toyokuni
Shinya
S
Sommer
Clemens
C
Schwab
Stefan
S
D000818:Animals; D001273:Atmosphere Exposure Chambers; D002545:Brain Ischemia / Q000473:pathology / Q000517:prevention & control / Q000628:therapy*; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D006624:Hippocampus / Q000098:blood supply / Q000473:pathology; D006801:Humans; D006931:Hyperbaric Oxygenation / Q000379:methods*; D007150:Immunohistochemistry; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology* / Q000517:prevention & control; D008279:Magnetic Resonance Imaging; D008297:Male; D018384:Oxidative Stress / Q000276:immunology / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar