PRETREATMENT WITH NMDA RECEPTOR ANTAGONIST MK801 IMPROVES NEUROPHYSIOLOGICAL OUTCOME AFTER AN ACUTE SPINAL-CORD INJURY

The post-traumatic release of excitatory amino acids (EAA) and their a ctions on N-methyl-D-aspartate (NMDA) receptors plays a major role in the spinal cord secondary injury process. The neuronal damage caused b y the release of EAA may be reduced by NMDA-receptor channel blockers. To investigate the involvement of NMDA receptors in spinal cord injur y (SCI), we pretreated animals with the noncompetitive NMDA antagonist MK801 (1.0 mg kg(-1)) before a compressive acute SCI. Pretreated anim als with MK801 significantly (p = 0.038) improved the recovery of func tion as measured by evoked potential activities. Morphologically, spec imens from rats treated with MK801 were characterized by milder and mo re localized hemorrhage in the gray matter. Immunohistochemical staini ng for glial fibrillary acidic protein (GFAP) and neurofilament (NF) h istochemistry showed leakage of these antigens in traumatized cord whi le characteristic staining of astrocytes and neurons and their process es was observed in morphologically preserved tissue. The loss of NF im munoreactivity was reduced by MK801 treatment.