Anti-nociceptive effect of bee venom treatment on chronic arthritic pain in rats

Bee venom (BV) has been traditionally applied to relieve pain and to cure inflammatory diseases such as rheumatoid arthritis (RA) and neuritis. While several investigators have evaluated the anti-inflammatory effect of BV treatment, the anti-nociceptive effect of BV treatment on inflammatory pain is not reported. Therefore, we decided to evaluate the analgesic effect of BV treatment using Freund's adjuvant induced chronic arthritis model. Freund's adjuvant-induced arthritis has been used as an experimental animal model for RA in humans to assess the efficacy of the anti-inflammatory/analgesic drugs. In this study, subcutaneous BV treatment (1mg/kg/day) produced significantly reductions of symptoms related to arthritic pain (i.e. mechanical hyperalgesia and thermal hyperalgesia). The anti-nociceptive effect of BV was observed from at least 12 days after BV treatment. Furthermore, BV treatment significantly suppressed adjuvant induced Fos expression in lumbar spinal cord. We also found that local injection of BV into near the inflammatory site (especially Zusanli-acupoint) showed more potent analgesic effect on arthritic pain rather than distant injection of BV from inflammatory site (arbitrary side of back). The present study demonstrates that BV treatment has anti-nociceptive effect on arthritis induced inflammatory pain. The analgesic effect of BV on RA is probably mediated by the effect of BV itself or possible other mechanism such as counter-irritation. Furthermore, it is possible that BV acupuncture is one of the promising candidates for long-term therapy of RA.