PROKR2 and synovitis: It has been shown that Prokr2-positive neurons in the ST36 acupoint mediate the activation of SNS during acute inflammation.156 Based on ST36 acupoint, Chen and colleagues found that electroacupuncture at ipsilateral ST36-GB34 acupoints in OA rats significantly alleviates synovitis and joint pain by activating the local sympathetic noradrenergic signaling, suggesting a potential therapeutic effect for OA.157 Apart from electroacupuncture, sympathectomy in the early inflammatory phase or α-adrenergic agonists may also be potential approaches for treating OA synovitis.