NITRIC-OXIDE - A POSSIBLE ETIOLOGIC FACTOR IN SPINAL-CORD CAVITATION

To determine whether nitric oxide (NO) is related to spinal cord cavit ation, we treated mice that underwent spinal cord injury with N-G-mono -methyl-L-arginine (N-MMA). Spinal cord specimens were subjected to gl ial fibrillary acidic protein (GFAP) immunostaining, which is selectiv e for astrocytes. Spinal cord cavities and GFAP-positive glial cells a ppeared simultaneously at 3 days after spinal cord injury, and the cav ities enlarged at 7 days. In mice receiving N-MMA, the cavities were s ignificantly smaller than those in the mice that underwent spinal cord injury only. However, the numbers of GFAP-positive cells showed no di fference between these two groups. These experimental findings suggest that cavitation of the spinal cord is caused mainly by NO released fr om activated glial cells.