Objective: To observe the analgesic effect of heat-reinforcing needling manipulation for acute inflammatory arthritis and its underlying mechanism in experimental rheumatoid arthritis rabbits.
Methods: A total of 60 rabbits were randomized into control (n=6), model (n=6), needle-twirling (n=24) and heat-reinforcing (n=24) groups, and the later 2 groups were further divided into 0 h, 0.5 h, 1 h and 2 h subgroups,with 6 cases in each. Rheumatoid arthritis model was established by injecting mixed solution of egg-albumin (4 mg/ml) and equal volume of complete Freund's adjuvant (CFA) into the subcutaneous tissue (6 points around the shoulder, 0.2 ml/point). Fourteen days later,the injection was repeated once again,and another 6 days later, egg-albumin (0.4 ml, 20 mg/ml) solution was injected into the bilateral knee-joints. "Zusanli" (ST 36) and "Hegu" (LI 4) were punctured and stimulated by needle-twirling or by heat-reinforcing needling technique for 1 min, with the needle retained for 30 min. The pain threshold of the paw was detected with K+ import stimulation method. beta-EP and PGE2 contents of the joint tissue were assayed with radioimmunoassay.
Results: Compared with model group, the pain threshold of needle-twirling group and heat-reinforcing group at each time-point increased significantly (P<0.01, P<0.05). Compared with needle-twirling group, the pain threshold of heat-reinforcing group at 0.5 h, 1 h and 2 h subgroups increased significantly (P<0.05, P<0.01). Both beta-EP and PGE2 contents of model group were significantly higher than those of control group (P<0.01, P<0.05). In comparison with model group, beta-EP contents of needle-twirling group and heat-reinforcing group at each time-point increased significantly (P<0.01, P<0.05), and PGE2 contents of needle-twirling group and heat-reinforcing group at each time-point decreased significantly (P<0.01, P<0.05). The beta-EP content of heat-reinforcing group was significantly higher than that of needle-twirling group at 2 h (P<0.05), while PGE2 content of the former group was significantly lower than that of needle-twirling group at 0 h (P<0.01).
Conclusion: Both needle-twirling and heat-reinforcing needling can effectively raise the pain threshold in acute arthritis rabbits, which my be closely associated with their effects in upregulating beta-EP content and lowering PGE2 level in the local joint tissue. The analgesic effect of heat-reinforcing needling manipulation is superior to that of needle-twirling.