Edaravone inhibits JNK-c-Jun pathway and restores anti-oxidative defense after ischemia-reperfusion injury in aged rats

Abstract

Edaravone, a potent antioxidant, is currently being used in the management of acute ischemic stroke in relatively high-aged populations. Mitogen activated protein kinase (MAPK) pathways have been shown to play important roles in neuronal cell death. We examined the role of MAPK pathways and the effect of treatment with edaravone in the brain after cerebral ischemia-reperfusion (I/R) injury in a bilateral carotid artery occlusion (BCAO) model with ischemia for 85 min followed by reperfusion for 45 min in aged rats. Western immunoblotting, immunostaining, enzyme-linked immunosorbent assay (ELISA), spectrophotometry, terminal deoxynucleotidyl transferase nick end labeling (TUNEL) and triphenyl tetrazolium chloride (TTC) staining were performed to evaluate various proteins in the homogenate, c-Jun NH2-terminal kinase (JNK) in the tissue sections, protein carbonyl, glutathione peroxidase (GSHPx), apoptosis and infarct size, respectively. Our results showed that I/R injury resulted in a reduction of GSHPx, but protein carbonyl content and inducible nitric oxide synthase were increased. The activation of JNK and its downstream molecule c-Jun was significantly increased after injury, whereas the activities of p38 MAPK and extracellular-regulated kinase 1/2 were slightly but not significantly increased. Edaravone (3 mg/kg, i.v.) treatment significantly reduced all of these changes. Our findings suggest that the JNK pathway differentially mediates neuronal injury in aged rats after BCAO, and edaravone treatment significantly reduces the neuronal damage after I/R injury by inhibiting oxidative stress and the JNK-c-Jun pathway with concomitant inhibition of overall MAPK activity in the brains of aged rats.