Effects of Papaver rhoeas Extract on the Tolerance Development to Analgesic Effects of Morphine in Mice

Previous studies have shown that the extract of papaver rhoeas reduces morphinedependence, locomotor activity and reward. in present study, the effects of hydro-alcoholextract ofpapaver rhoeas on the tolerance to analgesic effects of morphine in mice have beeninvestigated using tail flick method. subcutaneous (s.c.) administration of morphine (1, 2, 5and 10 mg/kg) induced analgesia. however, intrapretoneal administration of the hydro-alcoholextract ofpapaver rhoeas (25, 50 and 100 mg/kg) had not an effects on analgesia. reduction ofanalgesic in mice pretreated with morphine (50 mg/kg, twice daily; for 3 days), alone, indicatedthat tolerance has been developed. hydro-alcohol extract of papaver rhoeas (25,50 and 100mg/kg, i.p.) administration, 30 min before each of three daily doses of morphine, attenuatedthe morphine tolerance dose-independently, indicating that administration ofthe extract reducesmorphine tolerance in mice.