MICROGLIAL RESPONSE TO UNILATERAL SPINAL CORD COMPRESSION IN RABBITS

Abstract

There have been several pathologic descriptions of the spinal cord compressed chronically. Microglial changes, however, have been described scarcely. In the present study, microglial responses to the anterior unilateral compression were investigated by immunohistochemistry in the rabbit model. The cervical spinal cord was unilaterally compressed with a small screw at C5. The microglial response in the compressed and the contralateral halves of the spinal cord were investigated after 48 hours with the lectin RCA-1 immunostaining. Microglia were classified morphologically into resting and reactive microglia. Under mild compression, the mild proliferation of reactive microglia was observed in the anterior horn of the compressed half. A few reactive microglia were observed in the anterior horn of the contralateral half. The total number of resting and reactive microglia in each area of the gray and white matters did not differ between the sham and mild compression groups. Under severe compression, marked proliferation of reactive microglia was observed around the cavity in the gray matter of the compressed half. Moderate proliferation of reactive microglia was observed in gray matter of the contralateral half. These findings suggested that the resting microglia transformed into the reactive microglia, but not proliferated in the early stage of compression myelopathy.