〔Abstract〕 Objective To explore the therapeutic mechanism of puerarin in treating rheumatoid arthritis (RA) rats based on the serine/tyrosine protein kinase B (AKT)-phosphorylated forkhead box protein O1 (FOXO1)-interleukin-9 (AKT-FOXO1-IL-9) signaling pathway. Methods 36 rats were randomly divided into a blank group, a model group, a positive control group, and low, medium, and high dose groups of puerarin. Except for the blank group, the other groups were induced with type II collagen to establish a RA rat model. After successful modeling, different doses of puerarin and methotrexate were given to treat the rats. The body mass and toe thickness of the rats were measured, and biochemical indicators of rat blood rheology were detected. X-ray was used to observe changes in rat joint morphology. Safranin green staining and Alixin blue staining were used to observe the pathology of rat joint tissue. ELISA was used to detect the levels of IL-9 and rheumatoid factors in rat serum, and Western blot was used to detect changes in levels of AKT and FOXO1. ResultsCompared with the blank group, the model group had the lowest toe thickness, and X-ray images showed more obvious segmental stenosis and more severe marginal bone invasion; scaly like changes appeared at the edges of joints stained with safranin green, accompanied by the exudation of inflammatory cells and increased proliferation and secretion of chondrocytes; the expression levels of inflammatory factors IL-9 and rheumatoid factors were the highest, and the expression levels of AKT and FOXO1 proteins were the highest ( P<0.05) . Compared with the model group, the toe thickness of rats treated with different doses of puerarin decreased; X-ray images showed that the puerarin treatment group of rats showed improvement in plantar joint stenosis and marginal bone invasion; the results of safranin green staining showed that after treatment with different doses of puerarin, the infiltration of inflammatory cells decreased, and the expression levels of inflammatory factor IL-9, rheumatoid factors, AKT, and FOXO1 proteins decreased significantly ( P<0.05), with the high-dose puerarin group showing the most significant difference. Compared with the high-dose puerarin group, the positive control group showed a significant decrease in the above results and statistical differences ( P<0.05). ConclusionPuerarin has a good therapeutic effect on rats with RA by inhibiting the AKT-FOXO1-IL-9 pathway. The high-dose puerarin group (60 mg/kg) has the best therapeutic effect and the results show a dose-response relationship.