PURPOSE.To assess the therapeutic potential of edaravone, a free radical scavenger that is used for the treatment of acute brain infarction and amyotrophic lateral sclerosis, in a mouse model of optic nerve injury (ONI).METHODS. Two microliters of edaravone (7.2 mM) or vehicle were injected intraocularly 3 minutes after ONI. Optical coherence tomography, retrograde labeling of retinal ganglion cells (RGCs), histopathology, and immunohistochemical analyses of phosphorylated apoptosis signal-regulating kinase-1 (ASK1) and p38 mitogen-activated protein kinase (MAPK) in the retina were performed after ONI. Reactive oxygen species (ROS) levels were assessed with a CellROX Green Reagent.RESULTS. Edaravone ameliorated ONI-induced ROS production, RGC death, and inner retinal degeneration. Also, activation of the ASK1-p38 MAPK pathway that induces RGC death following ONI was suppressed with edaravone treatment.
CONCLUSIONS.The results of this study suggest that intraocular administration of edaravone may be a useful treatment for posttraumatic complications.Keywords: edaravone, oxidative stress, neuroprotection, ASK1, retinal ganglion cell T raumatic optic neuropathy is a common clinical problem that occurs in 0.5% to 5% of patients with closed head injury.1 Damage to the optic nerve induces secondary swelling within the optic canal, accompanied by subsequent retinal ganglion cell (RGC) loss and optic nerve atrophy.2 Although no large natural history or randomized controlled trials have been published, corticosteroid therapy and optic canal decompression surgery are not considered to be effective for patients with traumatic optic neuropathy.3 Research into finding therapeutic targets for treatment of traumatic optic neuropathy indicated that neuroprotection might be an effective strategy and studies using an optic nerve injury (ONI) model in rodents have provided useful information. For example, neurotrophins, such as brain-derived neurotrophic factor and ciliary neurotrophic factor, protect retinal RGCs in an ONI model. [4][5][6] Also, inhibitors of glutamate receptors, tumor necrosis factor receptors, and nitric oxide synthase may be effective for RGC protection.
7-11The ONI model mimics some aspects of glaucoma, including RGC death induced by oxidative stress, and therefore, it is also a useful animal model for glaucoma.Edaravone is a free radical scavenger that has been used clinically to treat acute brain infarction and amyotrophic lateral sclerosis (ALS). Edaravone quenches hydroxyl radicals ( Á OH) and inhibits lipid peroxidation dependent and independent of Á OH. 12,13 In an in vitro cell culture study using the RGC-5 to study the neurobiology of RGCs, edaravone scavenged the intracellular Á OH, superoxide anion (O 2 ÀÁ ), and hydrogen peroxide (H 2 O 2 ) while demonstrating the strongest scavenging activity against14 Recent studies have shown that oxidative stress plays an important role in many ocular diseases including glaucoma. [15][16][17][18] Interestingly, edaravone attenuates retinal ischemia/reperfusion ...