Abstract: Objective The expression of ASICs is closely related to the destruction of articular cartilage in rats due to inflammation leading to localized acidification of the joints in the course of RA.In this study,we investigated the effect of amygdalin on the immune response of articular synovium in CIA rats,and discussed the mechanism of amygdalin against RA. Methods Forty-five Wistar female rats were randomly selected for the blank control group.Thirty-five CIA rat models were randomly divided into model group(n=5),tripterygium wilfordii polyglycoside group(ie,positive control group),high dose of amygdalin and low dose of amygdalin.Blank control group and CIA model group were given 0.9% saline,Tripterygium wilfordii polyglycoside group to give tripterygium polyglycoside 1 mg/(kg·d),amygdalin high dose group to 120 mg/(kg·d),low amygdalin low dose group to 60 mg/(kg·d),once a day after continuous administration of oral administration 28 d,by abdominal anesthesia,femoral artery blood,conventional serum for IL-1β,sICAM-1 detection;separation of the left knee synovial membrane with 40 g/L Polyoxymethylene was used as HE staining specimen.The right knee joint synovial tissue was stored at -80℃ for preservation of Western blot ASIC3 protein.Simultaneous extraction of brain tissue at -80℃ was performed as a positive control. Results HE staining showed that the synovial cells in the CIA model group showed evacuation,disorder,hyperplasia and inflammatory cell infiltration.The mild hyperplasia and inflammatory cell infiltration of the high dose group,low dose group and Tripterygium wilfordii polyglycoside group were significantly decreased(P<0.05).Compared with the blank group,the levels of IL-1β and sICAM-1 in the peripheral blood were significantly decreased,and the expression of ASIC3 protein in the synovium was significantly decreased.There was no significant difference(P>0.05). Conclusion Amygdalin can effectively inhibit the expression of inflammatory cytokines IL-1β and sICAM-1 in peripheral blood of CIA rats and down-regulate the expression of synovial membrane ASIC3 protein,interfere with the damage of synovial membrane,immunosuppressive effects,may be amygdalin anti-inflammatory analgesic and protective cartilage effect of one of the mechanisms.