OBJECTIVETo compare the anti-inflammatory and anti-nociceptive effects of the different water extracts which were prepared by regular decoction time or removing volatie oil and ethanol extracts which were prepared in different concentration ethanol of Xixin (the roots and rhizomes of Asarum heterotropoides var. mandshuricum), and then to investigate the anti-inflammatory and antinociceptive mechanisms.

METHODXylene-induced ICR mouse ear edema and hot plate test were utilized to evaluate the anti-inflammatory and anti-nociceptive effects of Xixin at different dose level (water extracts of regular decoction time or removing volatie oil at the dose of 0.8 g x kg(-1) and 1.6 g x kg(-1); 95% ethanol extracts at the dose of 0.91 g x kg(-1) and 1.82 g x kg(-1); 50% ethanol extracts at the dose of 0.76 g x kg(-1) and 1.52 g x kg(-1)). Xylene-induced adrenalectomized mouse ear edema model was used to study the anti-inflammatory mechanisms. To reveal the anti-nociceptive mechanisms, mice were pretreated with naloxone in the hot plate test.

RESULTThe water extracts significantly reduced the weight of ear edema as compared with control group. Inhibition ratios were 43.20% and 63.69% at the higher dose, respectively. The ethanol extracts also significantly reduced the weight of ear edema and the inhibition ratios were 61.86% and 52. 56% at the higher dose, respectively. Mice administered water extracts delayed the latency times in the hot plate test. The anti-nociceptive effects of water extracts peaked at 2.0 h after i.g. administration. The hot plate latency times were increased by 51.27%, 62.78%, 60.08% and 68.00% at peak time, respectively. Regular decoction time group showed more significant effects in both models. The anti-inflammatory effect of 95% ethanol extracts was similar to 50% ethanol extracts. The water extracts were not effective in reducing xylene-induced adrenalectomized mouse ear edema. The anti-nociceptive effect of water extracts was blocked by naloxone.

CONCLUSIONBoth the water extracts and ethanol extracts of Xixin showed considerable anti-inflammatory potency against xylene induced inflammation. The water extracts produced anti-nociception in thermal model. The water extracts prepared in regular decoction time showed better anti-inflammatory and anti-nociceptive effects. Both the 95% ethanol and 50% ethanol extracts showed similarly anti-inflammatory effects. The anti-inflammatory effect of water extracts related to adrenal gland. The anti-nociceptive effect of water extracts was involved in activating opioid receptor.