Effect of Free Radical Scavenger Edaravone on Experimental Spinal Cord Injury : Functional Recovery and Axonal Protection

Generation of free radical plays an important role in development of secondary spinal cord injury (SCI). Edaravone is a free radical scavenger, and has been used for protection against ischemia in patients with cerebral infarction. We investigated the effect of edaravone on severe experimental SCI. Treatment with edaravone (3mg/kg of body weight administered intravenously and subcutaneously (s.c.) immediately after injury, plus 3mg/kg s.c. on day 1 and day 2) was compared with saline treatment in rats subjected to severe 50 g · cm weight drop thoracic SCI. Neurological recovery was evaluated periodically over 3 weeks by BBB locomotor rating scale and inclined plane method (IPM). To investigate protective effect of edaravone on axons, we evaluated the preservation of rubrospinal tract by counting red nucleus (RN) cells labeled retrogradely from lumbar spinal cord with fluorescent tracer. Edaravone significantly improved recovery in early phase in both BBB scale and IPM. The number of labeled RN neurons of edaravone-treated group had a tendency to be larger than of control group. These results indicate that edaravone has therapeutic potential for protecting the injured spinal cord.