Visceral antinociception produced by bee venom stimulation of the Zhongwanacupuncture point in mice: role of alpha(2) adrenoceptors

The goal of the present study was to determine whether bee venom (BV) injec tion into the Zhongwan acupoint (CV12), compared to injection into a non-ac upoint, produced antinociception in an acetic acid-induced visceral pain mo del. This was accomplished by injecting BV subcutaneously into the Zhongwan acupoint or into a non-acupoint 30 min before intraperitoneal injection of acetic acid in ICR mice. BV injection into the acupoint produced a dose de pendent suppression of acetic acid-induced abdominal stretches and of aceti c acid-induced Fos expression in the spinal cord and the nucleus tractus so litarii. In contrast BV injection into the non-acupoint only produced antin ociception at the highest dose of BV tested. Naloxone pretreatment did not alter the antinociceptive effect of BV acupoint injection on the abdominal stretch reflex. On the other hand, pretreatment with the alpha2-adrenocepto r antagonist, yohimbine completely blocked the antinociceptive effect of BV acupoint injection. These results imply that BV acupoint stimulation can p roduce visceral antinociception that is associated with activation of alpha 2-adrenoceptors, but not with naloxone-sensitive opioid receptors. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.