Study on the effect of ethanolic extract from aerial part of Achillea millefolium, on the development of tolerance to morphine analgesia in rat

Abstract

Background long term use of opiates can lead to development of tolerance to their analgesic effects. It has been shown that increase in proinflammatory factors and oxidative stress are indicated in dicreesing the analgesic effect of morphine. Achillea millefolium can show anti-inflammatory, analgesic and antioxidant effects due to fenolic compounds and felavenoids. Therefore, it may delay tolerance to the analgesic effects of morphine.

Objectives The aim of the present study was to evaluate the effect of chronic use of Achillea millefolium extract on tolerance to morphine analgesic effects in male rats.

Methods Ethanolic extract of A. millefoliom was obtained via maceration with soxhlet method. Seven groups of male rats were investigated in this study that included: morphine injected group (10 mg/kg), morphine and vehicle administered group (1ml/kg , 25% DMSO and 75% NS),morphine and three doses of extract administered groups (25,50,100 mg/kg) and control group and finally the last group was administrated the most effective dose of extract (100 mg/kg) alone. At the beginning after taking BL, a hot plate test (52˚c ± 0.5) was performed every other day half an hour after the drug injections.

Results In the group receiving morphine and the group receiving the extract vehicle with morphine, tolerance was established on the 9th day, while in groups receiving different doses of extract (25,50,100 mg/kg) tolerance was established on days 9,15 and 23 respectively. There was a significant difference in the level of MDA between morphine received group and the most effective dose of extract (p < 0.001).

Conclusion According to the results, ethanolic extract of A. millefolium could delay tolerance to analgesic effect of morphine, and the most effective dose of the extract also had a higher antioxidant activity than the morphine control group