The Effects And Mechanisms Of Melatonin On Collagen-induced Arthritis In Mice

Objective To investigate the prophylactic and therapeutic effects and mechanisms ofmelatonin on collagen-induced arthritis (CIA) in mice.Methods The model of CIA in mice was prepared and the change of secondarypaw-swelling and the mean scores of arthritis were observed. Indexs of immuneorgan(thymus and spleen) were also examined. The level of PGE was assayed byspectrophotometer; Meanwhile, 3H-TdR incorporation method was used to detectConA- and LPS- induced splenocytes proliferation and the production of interleukin(IL)-1 and IL-2. The content of antibodies to CII was determined by ELISA method.Pathological examination of articulus tissue was observed by Hematoxylin-eosin (HE)stain.Result Treatment of igmelatonin(10, 100, 1000 g kg-1) significantly decreasedinflammation of the arthritis and content of PGE in ankle. The increased index of spleenand thymic lymphocyte or splenocytes proliferation induced by LPS or ConA werereversed by melatonin. Meanwhile, production of IL-1 and IL-2 by peritonealmacrophages and T cells respective was inhibited by melatonin. Content of antibodies toCII in serum also decreased. The pathological examination results showed that articuluscartilage degeneration with synovial hyperplasia and inflammatory cells infiltration inCIA mice was suppressed by melatonin.Conclusion Melatonin had prophylactic and therapeutic effects on CIA in mice, whichmay be related to its immunoregulative function and inhibiting the production ofpro-inflammation mediator.