Pii: S0091-3057(96)00314-0
نویسندگان
چکیده
MATSUMOTO, K., M. MIZOWAKI, H. TAKAYAMA, S.-I. SAKAI, N. AIMI, AND H. WATANABE. Suppressive effect of mitragynine on the 5-methoxy-N,N-dimethyltryptamine-induced head-twitch response in mice. PHARMACOL BIOCHEM BEHAV 57(1/2) 319–323, 1997.—We investigated the effects of mitragynine, a major alkaloid isolated from the leaves of Mitragyna speciosa Korth (Rubiaceae), on the 5-HT2A receptor-mediated head-twitch response in mice. Intraperitoneal injection of mitragynine (5–30 mg/kg), as well as intraperitoneal injection of 5-HT2A receptor antagonist ritanserin, inhibited the 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT; 16 mg/kg, IP)-induced head-twitch response in a dosedependent manner. In contrast, mitragynine affected neither head-weaving caused by 5-MeO-DMT, nor drug-free spontaneous motor activity. Pretreatment of mice with reserpine (5 mg/kg, IP), p-chlorophenylalanine (p-CPA, 300 mg/kg 3 3 times, IP), or 6-hydroxydopamine (6-OHDA, 50 mg/mouse, ICV) plus nomifensine (5 mg/kg, IP) did not change the suppressant effect of mitragynine on the head-twitch response caused by 5-MeO-DMT. On the other hand, the a2-adrenoceptor antagonists yohimbine (0.5 mg/kg, IP), and idazoxan (0.2 mg/kg, IP), significantly attenuated the suppressant effect of mitragynine. Lesion of central noradrenergic systems by 6-OHDA plus nomifensine did not alter the effect of idazoxan (0.2 mg/kg) on mitragynine-induced suppression of the head-twitch response. These results indicate that stimulation of postsynaptic a2adrenoceptor, blockade of 5-HT2A receptors, or both, are involved in suppression of 5-HT2A receptor-mediated head-twitch response by mitragynine. 1997 Elsevier Science Inc.
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