Involvement of opioid and monoaminergic pain pathways in Aegle marmelos induced analgesia in mice

OBJECTIVE: To study analgesic activity and to evaluate the involvement of opioid and monoamines in the antinociceptive activity of methanol extract of leaves of Aegle marmelos. MATERIALS AND METHODS: Analgesic activity of methanol extract (ME) of A. marmelos alone (75,150 and 300mg/kg orally) and in combination with morphine or venlafaxine (subanalgesic) were studied using tail flick test and acetic acid-induced writhing in mice. The effect of pre-treatment with opioid antagonist naltrexone 1mg/kg was also studied on antinociception induced due to ME. RESULT: ME produced a dose-dependent significant antinociceptive activity in the tail flick test and acetic acid-induced writhing in mice. (P<0.05) Administration of subanalgesic dose of ME with morphine or venlafaxine also resulted in significant (P<0.05) antinociceptive activity in both the pain models. Pre-treatment with naltrexone inhibited analgesic activity induced by ME alone and combination with morphine or venlafaxine. CONCLUSION: A.marmelos in induced antinociception is mediated through both opioid and monoaminergic pain pathways, suggest its possible use in chronic pain.