Antinociceptive effects of bee venom acupuncture (apipuncture) in rodent animal models: A comparative study of acupoint versus non-acupoint stimulation

From a clinical perspective, the alternative forms of acupoint stimulation including electroacupuncture, moxibustion and acupressure appear to have more potent analgesic effects than manual needle acupuncture. Bee venom (BV) injection has also been reported to produce persistent nociceptive stimulation and to cause neuronal activation in the spinal cord. In previous study, we observed that BV stimulation into acupoint, namely BV acupuncture or Apipuncture, produced more potent anti-inflammatory and antinociceptive potency in rodent arthritis model as comparing with that of non-acupoint injection. Based on previous report, we decided to further investigate that BV injection into an acupoint produces antinociception as a result of its potent chemical stimulatory effect in both abdominal stretch assay and formalin test. Different doses of BV were injected into an acupoint or a non-acupoint 30 min prior to intraplantar formalin injection or intraperitoneal acetic acid injection. Using the abdominal stretch assay, we found that the high dose of BV (1:100 diluted in 20μl saline) produced a potent antinociceptive effect irrespective of the site of BV injection. In contrast the antinociceptive effect observed in both the writhing and formalin tests following administration of a low dose of BV (1:1000 diluted in 20μl saline) was significantly different between acupoint and non-acupoint sites. BV injection into an acupoint (Zhongwan, Cv. 12) was found to produce significantly greater antinociception than non-acupoint injection (10 mm from Zhongwan, Cv. 12) in the abdominal stretch assay. Similarly, in the formalin test, acupoint (Zusanli, St. 36) injection of BV produced more potent antinociception than non-acupoint injection (gluteal muscle). In contrast, BV injection into an arbitrary non-acupoint site on the back did not produce antinociception in either the writhing or formalin test. These results indicate that BV injection directly into an acupoint can produce a potent antinociceptive effect and suggest that this alternative form of acupoint stimulation (Apipuncture) may be a promising method for the relief of pain.