Objective      To determine the efficacy and possible mechanism of glucocorticoid at different doses in complex regional pain syndrome type 1 (CRPS1) rat model and its effect on serum P substance (SP)

macrophage migration inhibitory factor (MIF) and tumor necrosis factor alpha (TNF-α).       Methods       Thirty adult health SD rats were randomly divided into control group

treatment-1 group and treatment-2 group with 10 rats in each group. Methylprednisolone (MP) was abdominally administered in treatment-1 group [4 mg/(kg·d)] and treatment-2 group [20 mg/(kg·d)]. Pain behaviors were observed after 1-week-treatment. Serum SP

MIF and TNF-α were measured by ELISA at 8 h

1 and 3 weeks after 1-week-treatment.       Results      Hindpaw edema and pain was better after 1-week-treatment in 2 groups. T-2 group had higher pain threshold and lower serum levels of SP

MIF and TNF-α when compared to T-1 group and control group (P0.01

0.05).       Conclusion      It is suggested high-dose glucocorticoid is more effective in releasing edema and pain in CRPS1 rat model than low-dose glucocorticoid. Glucocorticoid might be through instantly suppressing some inflammatory factors. The difference of different doses of glucocorticoid might be due to whether suppresses MIF.