RESUMO
OBJECTIVE: To compare the analgesic effect of manual acupuncture(MA) stimulation of "Zusanli" (ST36) in rats with inflammatory pain under unrestrained conscious, restrained and general anesthesia conditions, so as to explore the applicability of unrestrained conscious model in the evaluation of acupuncture analgesia effect. METHODS: Male SD rats were divided into 5 groups: blank control (n=9), pain model (n=7), unrestrained conscious conditions+MA (n=6), restrained conditions+MA (n=6), and general anesthesia (GA)+MA(n=6). The acute pain model was established by injection of complete Freund's adjuvant (CFA) into the left ankle joint 48 h ahead of acupuncture. Subsequently, a single 20 min session of MA was applied to the left ST36. The mechanical and thermal pain thresholds (MPT and TPT) were determined before and after injection of CFA, and after MA stimulation. In order to evaluate the autonomic behavior activities, rats were randomly divided into blank control (n=11), pain model (n=11) and conscious-unrestrained conditions +MA (n=12) groups. The rats' exploratory movements were assessed by open field tests. RESULTS: Both MPT and TPT were significantly decreased after injection of CFA in the model group relevant to the blank control group (P0.05). No significant changes were found in the total moving distance after MA and in the central area moving distance after modeling and MA (P>0.05). CONCLUSION: MA has a better therapeutic effect in relieving pain and pain-induced depression-like behavior in conscious unrestrained rats than in restrained and GA rats, implying a higher applicability of unrestrained conscious pain model to the assessment of acupuncture analgesia.