Antinociceptive mechanisms of Bunium persicum essential oil in the mouse writhing test: role of opioidergic and histaminergic systems

Bunium persicum (Boiss.) is an economically important medicinal plant growing wildly in arid regions in Iran. The fruit of B. persicum is widely used in traditional Iranian medicine to control colic pain and dysmenorrhoea. The aim of the current study was to determine antinociceptive mechanisms of B. persicum essential oil using an acetic acid-induced writhing test as a model of visceral pain and to determine the possible involvement of opioidergic, serotoninergic and histaminergic systems on antinociceptive mechanisms of B. persicum in male mice. In experiment 1, B. persicum was intraperitoneally (i.p.) injected (0.001, 0.01, 0.05, 0.1, 0.5 and 1%; 10 ml/kg) in Tween-80 (0.5%) and a writhing test served as a model of visceral pain. In experiments 2-5, opioidergic receptor antagonist (naloxone, 2 mg/kg), serotonergic receptor antagonist (cyproheptadine, 4 mg/kg), histamine H1-receptor antagonist (chlorpheniramine, 20 mg/kg) and histamine H2-receptor antagonist (cimetidine, 12.5mg/kg) injection was followed by B. persicum (0.01%; 10 ml/kg) and the writhing test response was measured for 30 min. According to the results, essential oil of B. persicum, administered i.p. (0.001, 0.01, 0.05, 0.1, 0.5, and 1%; 10 ml/kg) in Tween-80 (0.5%), elicited antinociceptive effects in a dose-dependent manner. Moreover, the antinociceptive effect of B. persicum was significantly attenuated by pre-treatment with naloxone, chlorpheniramine and cimetidine (P < 0.001). These results suggest that B. persicum-induced analgesia may be mediated via opioidergic and histamine H1 and H2 receptors.