Keywords:morphine;bee venom test;spontaneous pain;antinociceptive;rat

    Abstract:AIM To compare two methods of quantitating spontaneous pain-related responses on evaluating the anal-gesic effect of morphine.METHODS After subcutaneous injection of bee venom into the plantar of one hindpaw in rats，the nociceptive responses were evaluated by two differ-ent methods:by counting the number of flinching reflex and by the four grade weight scoring.RESULTS The suppres-sive effect of pretreatment with morphine i.v.was found.Pretreatment with0.015，0.15，0.3，0.47，1.5，3.0mg kg-1 morpine i.v.significantly produced a dose-dependent suppression of the bee venom-induced spontaneous pain-relat-ed responses(P<0.05).The inhibitory rates were17，39，48，52，62and89per cent.The ED50 of morphine was0.29mg kg-1 .Pretreatment with1.5mg kg-1 morphine i.v.produced significant suppression on the bee venom-induced lifting/licking nociceptive score.CONCLUSION Pretreat-ment with morphine i.v.can produce a dose-dependent sup-pression on the bee venom-induced spontaneous flinching re-flex.In the bee venom test，the spontaneous flinching reflex as quantitative measure of spontaneous pain-related responses is more simple ......