ObjectiveTo explore the effect of blocking the JAK/STAT signal pathway on the activity of Caspase-3 in the synovial tissue of rheumatoid arthritis rats.MethodsFifty rat models of collageninduced arthritis,which had arthritis index more than 2 were divided into the model group,the low dosage of AG490 group,the medium dosage of AG490 group and high dosage of AG490 group.Inaddition,6 rats were treated as normal control group.Normal saline,AG490 1,5,10 mg·kg-1 ·d-1 were given by intraperitoneal injection.Then the volume claws and pathologic scores of the rat models were recorded and the activity of Caspase-3 in the synovial tissue were compared.The results were analyzed by one-way ANOVA and LSD-t or Tamhane's T2 test.ResultsThe arthritis of the CIA models progressed fast,the volume of the claws and the pathological score of them were significantly higher than those of the control group.At the same time,no Caspase-3 positive express could be detected in the control group,whilethe model group had slightly increased expression.After different dosages of AG490 were applied,the swollen of joints was significantly improved compared with the model group.The histopathological score of the medium AG490 dosage of group and high dosage group(2.7±0.8,1.8+0.9) were remarkably decreased than those of the model group(4.3+1.2),the differences were statistically significant (P＜0.01).In addition,the Caspase-3 expression in the low,medium and high AG490 dosage group ( 1.90±0.15,3.13±0.33,3.56+0.34) was significantly higher than that of the model group(1.48±0.18)(P＜0.05 or P＜0.01 ).ConclusionBlocking JAK/STAT signal pathway can increase the activity of Caspase-3,reduce the excessive proliferation of synovial tissue,and improve arthritis symptoms.