Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Paper Med Princ Pract 2011;20:66–70 DOI: 10.1159/000319763 Involvement of Opioid, Adenosine and 5-HT 3 Receptors in Antinociceptive Effects of an Ayurvedic Polyherbal Formulation S.B. Chandrasekar   a Kalyani Divakar   a A.T. Pawar   a Divakar Goli   a R. Harisha   b M. Bhanumathy   c G. Sushma   c H.N. Shivaprasad   c a  Department of Pharmacology, Acharya BM Reddy College of Pharmacy, Soldevanahalli, b  Milind Institute of Pharmacy, Kurubarahalli, and c  Natural Remedies Pvt. Ltd., Bangalore, India lation apparently involved an opiate-like mechanism, since its antinociceptive action was attenuated by naloxone pre- treatment. In addition, antinociceptive activity was attenu- ated by caffeine and reversed by ondansetron pretreatment. Conclusion: Our data suggest that the polyherbal formula- tion possessed centrally and peripherally mediated antino- ciceptive properties. The activity could be mediated through opioid, adenosine, and serotonin receptors and via inhibi- tion of cyclo-oxygenase- and/or lipoxygenase-dependent pathways. Copyright © 2010 S. Karger AG, Basel Introduction From time immemorial, plants have served as the pri- mary source of medicines and food, and they have con- tinued to provide mankind with new and novel therapeu- tic remedies to date. Over the last four decades, there has been a remarkably steady resurgence of interest in the study and use of medicinal plants. This current renewed global interest in the study and use of medicinal plants has led to the characterization and identification of novel lead molecules, and the isolation of active chemical com- pounds of potential therapeutic value. This revival of in- terest in plant-derived drugs is mainly due to the wide- spread belief that ‘natural medicines’ are safe and more dependable than costly synthetic pharmaceutical drugs, Key Words Acetic acid-induced writhing  Antinociceptive  Diclofenac sodium  Pethidine  Polyherbal formulation  Tail immersion test Abstract Objective: The present study was undertaken to evaluate the antinociceptive effects of an ayurvedic polyherbal for- mulation in rats and mice employing the tail immersion test and acetic acid-induced writhing test, respectively. Materi- als and Methods: With the tail immersion method, rats re- ceived two different doses (270 and 405 mg/kg BW, p.o.) of a formulation, pethidine (5.4 mg/kg BW, p.o.) as a reference standard and the combination of the higher dose of the for- mulation with naloxone (2 mg/kg, i.p.), an opioid receptor antagonist, and caffeine (16 mg/kg, i.p.), used as an adeno- sine receptor antagonist. In the acetic acid-induced writhing test, mice received two different doses (390 and 585 mg/kg, BW, p.o.) of formulation, diclofenac sodium (15 mg/kg, BW, p.o.) as a reference standard and the combination of the higher dose of the polyherbal formulation with ondansetron (0.5 mg/kg, i.p.), a serotonin receptor antagonist. Results: The polyherbal formulation (405 mg/kg) exhibited a signifi- cant (p ! 0.01) antinociceptive effect using the tail immer- sion method. In the acetic acid-induced writhing test, the formulation showed significant (p ! 0.01) dose-dependent activity. The antinociceptive effect of the polyherbal formu- Received: October 21, 2009 Accepted: April 19, 2010 S.B. Chandrasekar, M. Pharm. Department of Pharmacology, Acharya BM Reddy College of Pharmacy Soldevanahalli, Hesaraghatta Main Road, Chikabhanavara Post Bangalore 90, Karnataka (India) Tel. +91 99 8638 7768, E-Mail sbchandrasekar  @  gmail.com © 2010 S. Karger AG, Basel 1011–7571/11/0201–0066$38.00/0 Accessible online at: www.karger.com/mpp