BACKGROUND: It demonstrates that erhuangfang can improve clinical symptoms of multiple sclerosis and relieve side effects of hormone. However, whether erhuangfang can improve experimental allergic encephalomyelitis (EAE) or not needs a further study.OBJECTIVE: To observe the effect of erhuangfang on neuro-pathology and astrocyte in EAE rats and compare with the effect of hormone.DESIGN: Randomized controlled animal study.SETTINGS: Department of Traditional Chinese Medicine, Beijing Tiantan Hospital, Capital Medical University; College of Traditional Chinese Medicine, Capital Medical University.MATERIALS: The experiment was carried out in the Laboratory Center of Capital Medical University from August to October 2005. Ten adult guinea pigs (SPF grade, weighing 400 - 450 g) and 70 adult Lewis rats (SPF grade, weighing 200- 220 g) were selected in this study. Erhuangfang consisted of jiudahuang,shengdi, shuizhi, dabeimu, etc.METHODS: ① Experimental intervention: Rats were randomly divided into normal group (n=10), model group (n=20), western medicine group (n=20) and Chinese herb group (n=20). Mixed emulsion, which was consisted of Freund's adjuvant and spinal cord homogenate of guinea pigs, was subcutaneously injected into palms of the two hindfeet of rats in the latter three groups to establish EAE models. Foot pads were injected with saline and then rats were perfused with saline in the normal group. In the model group, models were established as the same as those mentioned above, and rats were also perfused with saline. Rats in the western medicine group were perfused with saline and then 5 mg/kg prednisone acetate suspension. Rats in the Chinese herb group were perfused with erhuangfang decoction (15 g raw materials per kilogram) at 5 days before model establishment. The dosage in the four groups was 3 mL/day per rat. ② Experimental evaluation: At 28 days after model establishment, rats were randomly selected for cerebral (mainly surrounding cerebral ventricle) and spinal cord (cervical enlargement and lumbar enlargement) collections,and then haematine-eosin (HE) staining and SLG myelin staining were used to observe demyelination and regeneration; meanwhile, immunohistochemical staining was used to observe the expression of glial fibriliary acidic protein (GFAP).MAIN OUTCOME MEASURES: Cerebral and spinal demyelination and regeneration as well as expression of GFAP in EAE rats.RESULTS: All 70 Lewis rats were involved in the final analysis. ① Demyelination and regeneration:Infiltration of inflammatory cells surrounding cerebrum and small venous vessels of spinal cord white matter,demyelination surrounding vessels and plentiful foam cells at myelinolysis sites were observed in the model group. Symptoms were relieved in the western medicine group and the Chinese herb group as compared with those in the model group. While, numbers of inflammatory infiltrated cells and vascular cuffs were decreased in focal region as compared with those in the model group; in addition, areas of softening focus and demyelination were decreased. ② Expression of GFAP: Volumes and numbers of positive cells of GFAP in white matter region were respectively bigger and higher than those of normal cells in the model group.Plentiful positive cells of GFAP were disorderly aggregated in hippocampus and surrounding small vessel cuffs. While, expression of GFAP was mildly increased surrounding focus in the Chinese herb group;however, GFAP did not express surrounding focus in the western medicine group. In addition, expressions of GFAP were not increased in non-focal region in both Chinese herb group and western medicine group.CONCLUSION: Both erhuangfang and hormone can relieve inflammatory reaction of central nervous system and demyelination of EAE rats. On one hand, erhuangfang can regulate reaction of astrocyte in two ways, relieve reaction and proliferation of astrocyte in non-focal region and maintain the protective effect of astrocyte on brain tissue in focal region; on the other hand, hormone can overall inhibit reaction of astrocyte.