Analgesic effect of buccal acupuncture on acute arthritis in rabbits and underlying mechanisms

Abstract

To observe the analgesic effect of acupuncture and to explore its central analgesic mechanism in rheumatoid arthritis rabbits. Methods: A total of 60 flap-eared white rabbits were randomly assigned into a normal control group (n=6), a model group (n=6), a body-acupuncture group (n=24), and a buccal acupuncture group (n=24). The later 2 groups were further randomly assigned into 0, 0.5, 1, and 2 h subgroups, with 6 cases in each group. The rheumatoid arthritis model was established by induction of egg-albumin. In the body acupuncture group, bilateral "Xiyan" and "Zusanli" were punctured for 15 s while in the buccal acupuncture group, acupuncture was applied to "Xi" for 15 s, with the needle retaining for 30 min. The pain threshold was detected with PL-200, taking struggle movements of rabbits as a measurement index, response latency from irradiation to struggling movements as the rabbit's pain threshold. The contents of β-endorplhin (β-EP) and cholecystokinin-8 (CCK-8) in cerebrospinal fluid were examined by radioimmunoassay. Results: Compared with the control group, pain threshold and CCK-8 levels decreased significantly (P<0.01) and the concentration of β-EP significantly increased (P<0.05) in the model group. The pain threshold in the body-acupuncture group and the buccal acupuncture group at 0 and 1 h (P<0.05 or P<0.01) increased significantly, while the β-EP and CCK-8 contents in the body-acupuncture group and the buccal acupuncture group were significantly higher than those in the model group (P<0.01 or P<0.05). Both β-EP and CCK-8 contents in the buccal acupuncture group at 0 h were significantly higher than those in the body-acupuncture group (P<0.05). Conclusion: The analgesic effect of buccal acupuncture is superior to that of body-acupuncture. Both buccal acupuncture and body-acupuncture can effectively raise the pain threshold in acute arthritis rabbits, which is closely associated with their effects in the up-regulation of β-EP and CCK-8 contents in cerebrospinal fluid.