Antinociception Profiles and Mechanisms of Orally Administered Aralia cordata Thunb. Extract in the Mouse

In the present study, the antinociceptive profiles of Aralia cordata Thunb. extract were examined in ICR mice. A. cordata extract administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate tests. A. cordata extract attenuated the writhing numbers in the acetic acid-induced writhing test and reduced the cumulative nociceptive response time for intrathecal (It.) injection of substance P (0.7 mu g). Intraperitoneal (i.p.) pretreatment with yohimbine (alpha(2)-adrenergic receptor antagonist) attenuated antinociceptive effect induced by A. cordata extract in the writhing test, whereas naloxone (opioid receptor antagonist) and methysergide (5HT2 serotonergic receptor antagonist) did not affect antinociception. Results suggest that A. cordata extract has an antinociceptive property in various pain models and may be mediated by alpha(2)-adrenergic receptor, but not by opioidergic and 5HT2 serotonergic receptors.