Effect of electroacupuncture on JAK2/STAT3 pathway in synovial tissues of rats with rheumatoid arthritis

Objective To observe the effect of electroacupuncture (EA) on Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway in knee joint synovial tissues of rats with rheumatoid arthritis (RA) and to explore the action mechanism of EA on RA. Methods Twelve of the 48 SPF male Sprague-Dawley (SD) rats were assigned to a normal group by the random number table method. The remaining 36 rats were subjected to RA model preparation by intradermal injection of the Freund's complete adjuvant into the right hind foot pad of each rat under sterile conditions. After the model was successfully prepared, rats were then divided into a model group, a drug group and an EA group according to a random number table method (n=12). Rats in the drug group were treated with 2 mL aqueous solution of tripterygium glycosides [8.1 mg/(kg center dot bw)]; rats in the EA group were treated with EA at bilateral Yanglingquan (GB 34) and Zusanli (ST 36), for 30 min each time; rats in the normal group and the model group were placed in a special rat fixation tank for 30 min each time, and received the same dose of normal saline as those in the drug group. Rats in all groups received intervention once a day for 4 weeks. Diameter of rat ankle joint and rat arthritis index were measured before and after the intervention. At the end of the experiment, the expressions of phospho-JAK2 and phospho-STAT3 were determined by immunohistochemistry. Quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect JAK2 and STAT3 mRNAs expressions. Results After the model was produced, the arthritis index <2 was considered successful in model preparation. Compared with the model group, the ankle joint diameters and arthritis indexes of rats in the drug group and the EA group were significantly lower (all P>0.01); immunohistochemical staining cells with phospho-JAK2 and phospho-STAT3 were significantly decreased (all P>0.01); the expression levels of JAK2 and STAT3 mRNAs were decreased with statistical differences (all P>0.01). There were no significant differences between the EA group and the drug group (all P<0.05). Conclusion EA can alleviate the inflammatory response of RA rats, improve their pathological conditions, reduce the expressions of phospho-JAK2 and phospho-STAT3 in the synovial tissue of knee joint, and decrease the expressions of JAK2 and STAT3 mRNAs. The therapeutic effect of EA is comparable to that of the tripterygium glycosides. The mechanism of EA treatment may be related to the inactivation of the JAK2/STAT3 pathway.