| Objective To explore early visual dysfunction in a rat model of experimental autoimmune encephalomyelitis (EAE) by monitoring functional combined with pathological techniques.Methods Established a Wistar rat model of EAE and recorded flash visual evoked potentials (F-VEP) in control group as normal reference value for this study. The EAE rats in experimental group were performed F-VEP tests at different time points after immunization. Animals were executed when the electrophysiological tests were finished by perfusing 4% paraformaldehyde 6 days after disease onset, and optic nerves, brains, spinal cords and sciatic nerves were removed for light and electron microscope pathological analysis. Quantitative techniques were utilized to examine relationships among F-VEP, optic nerve pathology and clinical scores.Results Disease incidence of EAE was 90% in experimental group. Distinct degrees of dysfunctions in electrophysiological responses as well as histological evidences in optic nerves were observed. F-VEP changes were characterized by prolonged latencies of P waves and N1 waves. Latencies of P and N1 waves were maximally prolonged by 59.58% and 35.33% respectively. Pathological studies demonstrated various degrees of inflammation and demyelination within CNS including optic nerves, and also sciatic nerves and spinal roots in periphery. Optic neuritis incidence was 77.8% of eyes by day 6 after disease onset. Demyelination changes were more obvious than inflammation in optic nerves. There was positive correlation between prolonged latency of P wave and optic nerve demyelination in this rat model of EAE(rs=0.533, P<0.05).Conclusions As visual function is remarkably impaired in this rat model of EAE, this model can be used for further study of inflammatory optic diseases. And F-VEP can be an operative indication during evaluating optic nerve involvement and monitoring pathological course of EAE.
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