Electroacupuncture at "Zusanli"(ST36) and "Xuanzhong"(GB39) improves inflammatory reactions and reduces levels of serum MMP-3 and MMP-9 in adjuvant arthritis rats

Abstract

To observe the effect of electroacupuncture (EA) at "Zusanli" (ST36) and "Xuanzhong" (GB39) on joint inflammatory reactions and serum matrix metalloproteinase-3 (MMP-3) and MMP-9 contents in rats with adjuvant arthritis (AA), so as to explore its mechanism underlying improvement of AA. Forty male SD rats were randomly divided into control, model, acupoint and non-acupoint groups (n=10 in each group). The arthritis model was established by hypodermic injection of complete Freund's adjuvant (0.1 mL) into the bilateral footpads. EA (2 Hz, 3 V) was applied to bilateral ST36 and GB39 or two non-acupoints (5 mm left to ST36 and GB39) for 15 min, once every other day for a total of 8 times. The arthritis index score was evaluated according to the severity of local erythema and swelling of the ankle joint, plantar joint, toe joint and foot metacarpal joint (0-4 points). The inflammatory conditions of the ankle joint were observed by H.E. staining, and the contents of serum MMP-3 and MMP-9 were assayed by ELISA. The arthritis index score and serum concentrations of MMP-3 and MMP-9 were significantly increased in the model group relevant to the control group (P<0.01), and obviously decreased after EA intervention on the 18th day (P<0.01). The therapeutic effect of acupoint EA was notably superior to non-acupoint EA in down-regulating the arthritis index score and serum MMP-3 and MMP-9 concentrations (P<0.01). Under light microscope, marked proliferation of the synovial cells, inflammatory cell infiltration and increase of newly blood vessels were observed in the ankle joint of the model group, which was relatively milder in the acupoint group. acupoint EA intervention can significantly alleviate the inflammatory reaction of AA rats, which may be related to its effects in reducing the levels of serum MMP-3 and MMP-9.