Objective: To probe into the mechanism of acupuncture analgesia.
Methods: Type-I collagenase was injected to destroy the structure of collagen fibers in the acupoint. Paw withdrawing latency and mast cell degranulation rate in the acute adjuvant arthritis rat were investigated. Effects of acupuncture at "Zusanli" (ST 36) with twirling or thrusting-lifting manipulation on acupuncture analgesia and mast cells were compared when the structures of collagen fibers in the acupoint were destroyed or not.
Results: When the structures of collagen fiber were destroyed, the analgesic effects of both acupuncture manipulations were attenuated and the degranulation rate of mast cells caused by acupuncture were significantly inhibited.
Conclusion: Collagen fibers and mast cells in the acupoint play an important role in acupuncture analgesia. Collagen fibers participate in transmission and transform process of acupuncture signs from the acupoint to the target organ, and the degranulation of mast cells is positively correlated with acupuncture analgesia.