Abstract

In the present study, the antinociceptive profiles of Aster koraiensis extract (AKE) were examined in ICR mice. AKE administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate paw-licking tests. In addition, AKE attenuated the writhing numbers in the acetic acid-induced writhing test. Moreover, the cumulative response time of nociceptive behaviors induced by an intraplantar formalin injection was reduced by AKE treatment during the 2nd phases. Furthermore, the cumulative nociceptive response time for intrathecal (i.t.) injection of substance P (0.7 µg) was diminished by AKE. Intraperitoneal (i.p.) pretreatment with yohimbine (α₂-adrenergic receptor antagonist) attenuated antinociceptive effect induced by AKE in the writhing test. However, naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist) did not affect antinociception induced by AKE in the writhing test. Our results suggest that AKE shows an antinociceptive property in various pain models. Furthermore, this antinociceptive effect of AKE may be mediated by α₂-adrenergic, but not opioidergic and serotonergic receptors.

Key words: Aster koraiensis, anti-nociception, inflammatory pain, α2 adrenoceptor.