Objective   To study the therapeutic effect of progesterone for rats with experimental allergic encephalomyelitis （EAE）.    Methods   The male Wistar rats were immunized with guinea pig’s spinal cord homogenate. After neurological symptoms occurred in the rats

intraperitoneal injection of  progesterone which was dissolved in 2.5 ml sesame oil was given to the therapeutic group at the dose of 4 mg/kg once a day for 4 d and the control group was given the same amount of sesame oil. All the rats were graded with the nerve function score. Their brains were examined by electron microscopy and stained by LFB and Marchi method. The IPP system was used to calculate the IOD values of normal and degenerative myelin.    Results   There was no significant difference in the nerve function score between therapeutic and control group. But in the 6th

10th

25th day after progesterone injection

the IOD values of normal myelin of therapeutic group were higher than those of control group. The IOD values of degenerative myelin of therapeutic group were lower than those of control group.    Conclusion   Progesterone is profit to the remyelination of central nervous system of the rats with experimental allergic encephalomyelitis.