In a previous report, subcutaneous injection of diluted bee venom (dBV) into a specific acupuncture point (Zusanli, ST36), a procedure termed apipuncture, was shown to produce an antinociceptive effect in the rat formalin pain model. However, the central antinociceptive mechanisms responsible for this effect have not been established. Traditional acupuncture-induced antinociception is considered to be mediated by activation of the descending pain inhibitory system (DPIS) including initiation of its opioidergic, adrenergic and serotonergic components. The purpose of the present study was to investigate whether the antinociceptive effect of apipuncture is also mediated by the DPIS. Behavioral experiments verified that apipuncture significantly reduces licking behavior in the late phase of formalin test in rats. This antinociceptive effect of apipuncture was not modified by intrathecal pretreatment with naltrexone (a non-selective opioid receptor antagonist), prazosin (a α 1 adrenoceptor antagonist) or propranolol (an β adrenoceptor antagonist). In contrast, intrathecally injected idazoxan (an α 2 adrenoceptor antagonist) or intrathecal methysergide (a serotonin receptor antagonist) significantly reversed apipuncture-induced antinociception. These results suggest that apipuncture-induced antinociception is produced by activation of α 2 adrenergic and serotonergic components of the DPIS.
Bibliographical noteFunding Information:
This research was supported by a grant (M103KV01000903K220100940) from the Brain Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology of the Republic of Korea. The publication of this manuscript was also supported by a Research Fund from the Research Institute for Veterinary Science (RIVS) in the College of Veterinary Medicine, Seoul National University, as well as the Brain Korea 21 project.
- Bee venom
- α Adrenergic