The gliotic scar in the demyelinated plaque is a prominent feature of the pathology of multiple sclerosis. Chronic relapsing experimental allergic encephalomyelitis (EAE) in the SJL/J mouse has many characteristics in common with multiple sclerosis in the human, including the development of intense gliosis during the course of the demyelinating disease. With the use of antibody to the astrocyte marker glial fibrillary acidic protein (GFAP) we have measured the increase of GFAP over an 11-month course of chronic EAE. Intense staining of astrocyte fibers was seen around EAE lesions, which were most frequently observed in the cerebellum, periventricular areas, and in the spinal cord. The relative amount of GFAP was estimated by preparation of cytoskeletai proteins from the affected CNS areas, separation of proteins by polyacrylamide gel electrophoresis, and quantitation of GFAP in relation to the 70-kD neurofilament protein (NF) in gel scans. The ratio GFAP/7O-kD NF protein in control animals did not change significantly over 11 months, whereas this ratio gradually increased to 2.54 in animals with chronic relapsing EAE 6 months after immunization. Although some decrease of neural fibers may have contributed partially to this change in ratio, the amounts of GFAP were greatly increased.
These results indicate that the SJL/J mouse with chronic relapsing EAE provides an excellent model with which to investigate the formation and development of the gliotic plaque analogous to that seen in demyelinated areas in multiple sclerosis tissue.