Objective: To observe the effect of norcantharidin(NCTD) on collagen-induced arthritis(CIA) rats. Methods: Sixty Sprague-Dawley(SD) rats were randomly divided into 6 groups(n=10): normal group, CIA model group(model group), NCTD low-dose group [1.35 mg/(kg·d)], NCTD middle-dose group [2.7 mg/(kg·d)], NCTD high-dose group [5.4 mg/(kg·d)] and methotrexate(MTX) group [1.8 mg/(kg/w)]. Anesthetized rats were sacrificed by luxation of cervical vertebra after 4 weeks of administration. The arthritis scores were evaluated twice a week. The pathological changes in the ankle joints of rats were observed by hematoxylin-eosin(H&E) staining. The serum levels of interleukin(IL) 1β, IL-6, tumor necrosis factor(TNF)-α, vascular endothelial growth factor(VEGF), IL-17 and transform growth factor(TGF) β were detected by enzyme linked immunosorbent assay(ELISA). The mRNA expression of retinoid-related orphan nuclear receptor γ t(ROR γ t) and forkhead box P3(Foxp3) in peripheral blood lymphocytes were confirmed by real-time polymerase chain reaction. Results: MTX and high-dose NCTD not only decreased the arthritis scores but also alleviated the pathological changes in CIA rats' ankle joints compared with the model group(P<0.05 or P<0.01). All doses of NCTD significantly inhibited the serum levels of IL-6, IL-17 and TNF-α in CIA rats(P<0.05). Only middle-and high-dose of NCTD prominently decreased serum IL-1β and TGF-β levels of CIA rats(P<0.05). However, NCTD has no effect on vascular endothelial growth factor(VEGF) level in CIA rats. The Foxp3 mRNA expression in all NCTD groups were increased significantly than in the model group(P<0.05). The mRNA expression of RORγt in NCTD high-dose group was decreased apparently in comparison with the model group(P<0.05). Conclusion: NCTD showed therapeutic effect on CIA rats by inhibition of cytokines and regulation of Th17/Treg cells.
