Antioxidant CR-6 Protects against Reperfusion Injury after a Transient Episode of Focal Brain Ischemia in Rats

Abstract

Oxidative and nitrosative stress are targets for intervention after ischemia/reperfusion. The aim of this study was to explore the effect of CR-6, a vitamin-E analogue that is antioxidant and scavenger of nitrogen-reactive species. Sprague-Dawley rats had the middle cerebral artery (MCA) occluded either for 90 mins or permanently. Cortical perfusion was continuously monitored by laser-Doppler flowmetry. CR-6 (100 mg/kg) was administered orally either at 2 and 8 h after MCA occlusion, or at 2 h only. Infarct volume, neurological deficit, and signs of reperfusion injury were evaluated. CR-6 was detected in plasma and brain by HPLC. CR-6 reduced glutathione consumption in the ischemic brain and superoxide generation in the isolated MCA. CR-6 decreased infarct volume and attenuated the neurological deficit at 1 and 7 days after ischemia/reperfusion, but not after permanent ischemia. Immediately after reperfusion, cortical blood flow values returned to their baseline ( ± 20%) in several animals, whereas others showed hyper-perfusion ( > 20% of baseline). Reactive hyperemia was associated with adverse events such as increased cortical BBB leakage, edema, protein nitrotyrosination, COX-2 expression, and neutrophil accumulation; and with a poorer outcome, and CR-6 attenuated these effects. In conclusion, oral CR-6 administration after transient ischemia protects the brain from reperfusion injury.

Middle cerebral artery remodeling following transient brain ischemia is linked to early postischemic hyperemia: A target of uric acid treatment

“…Sham-operated animals were also carried out by performing the full surgical procedure and by introducing the filament through the MCA for less than 1 min. A simple neurological test on a nine-point scale (0=no deficit to 9=highest handicap) was performed before killing the animals, as reported (23). At 24 h, rats were euthanized under deep isoflurane anesthesia, and the brain was removed and placed in cold Krebs-Henseleit solution (KHS) (14,15).…”

“…At 24 h, rats were euthanized under deep isoflurane anesthesia, and the brain was removed and placed in cold Krebs-Henseleit solution (KHS) (14,15). Evaluation of infarct volume was performed with the 2,3,5-triphenyltetrazolium chloride (Sigma-Aldrich, St. Louis, MO) technique, as described (23).…”

“…The surgical procedure for induction of focal cerebral ischemia was previously described (23). Rats were anesthetized with isoflurane (2.5-3%) vaporized in O 2 and N 2 O (30:70).…”

“…In a more recent study, rats that developed cortical hyperemia immediately after reperfusion showed larger cortical infarcts and worse neurological deficits than rats not showing hyperemia (23). Therefore, it is suggested that reactive hyperemia at early reperfusion could be a sign of reperfusion injury and also a potential target for therapeutic intervention.…”

“…NO can react with superoxide anion (O 2 .-) generated at reperfusion to form the potentially harmful molecule peroxynitrite (ONOO -) leading to tissue damage (4). Hyperemic rats show comparatively more brain protein nitrotyrosination that may contribute to the worse outcome (23).…”