OBJECTIVETo observe the pathological changes of axonal injury in a rat model of experimental allergic encephalomyelitis (EAE).

METHODSWith HE, luxol fast blue and Bielschowsky staining, the expression of APP, MBP, SMI-32 and MBP in the brain and spinal cord of EAE rats using double-labeling indirect immunofluorescence.

RESULTSExtensive cuffing lesions of inflammatory cell infiltrations were found in the brain and spinal cord of the rats, accompanied by multiple lesions of demyelination, axonal disarrangement with vesicular loss. SMI-32 staining identified numerous nonphosphorylated neurofilament, indicating the presence of axonal injury. Axonal oval bodies formed by APP accumulation were found in the white matters of the spinal cord 14 days after EAE, suggesting that neuraxial damage occurred in the early stage of EAE which was not synchronous with myelin loss.

CONCLUSIONDifferent levels of inflammation occur in different stages of EAE, and inflammatory cell infiltration is the most obvious at the peak of EAE. Axonal injury occurs in the early stage of EAE and progresses over the entire disease course.