Mechanism of anti-nociceptive effects of Asarum sieboldii Miq. radix: potential role of bradykinin, histamine and opioid receptor-mediated pathways.

The radix of Asarum sieboldii Miq. (AR) has been used to treat pain and inflammation in Korea. The present study was conducted to gain insights into the mechanism of actions regarding anti-nociceptive and anti-inflammatory activities of AR. Administration of methanol extract of AR caused dramatic anti-nociceptive effects based on acetic acid writhing and tail-flick assay. When naloxone (Nx) was pre-treated, AR extract failed to exert such anti-nociceptive effect in the tail-flick assays. These results suggest that AR extract have opioid-like activity. It also exerted significant anti-inflammatory effects in the rat paw edema assay. AR extract caused inhibition in the bradykinin (BK)/histamine-mediated ileum contractions of guinea pig. Taken together, these results provide evidence that the methanol extract of AR exerts anti-nociceptive and anti-inflammatory effects by activating opioid receptor as well as by inhibiting bradykinin and histamine-mediated actions.