Objective: To observe the effect of electroacupuncture (EA) on serum tumor necrosis factor-alpha (TNF-alpha), IL-1 and IL-4 levels in rats with chronic inflammatory pain, so as to investigate its underlying mechanism in relieving pain. Methods Forty-eight SD rats were randomized into control, model, EA-unilateral ST 36, and EA-bilateral ST 36 groups, with 12 rats in each. Chronic inflammatory pain model was established by intradermal injection of Freund's complete adjuvant (0.1 mL) into the right paw. EA (2 Hz/100 Hz, 1-2-3 mA) was applied to the unilateral "Zusanli" (ST 36) and bilateral "Zusanli" (ST 36) for 30 min, once every 3 days and continuously for 4 weeks. Serum TNF-alpha, IL-1 and IL-4 contents were detected by enzyme linked immunosorbent assay. Results Compared with the control group, serum TNF-alpha, IL-1 and IL-4 contents of the model group increased significantly (P < 0.01), while in comparison with the model group, the levels of the 3 indexes were decreased considerably in both unilateral and bilateral ST 36 groups (P < 0.01). No significant differences were found between the unilateral ST 36 and bilateral ST 36 groups in serum TNF-alpha, IL-1 and IL-4 contents (P > 0.05).
Conclusion: EA can effectively lower serum TNF-alpha, IL-1 and IL-4 levels in inflammatory pain rats, which may contribute to its effect in relieving inflammatory pain.