The effect of cannabinoids on motion-induced emesis is unknown. The present study investigated the action of phytocannabinoids against motion-induced emesis in Suncus murinus. Suncus murinus were injected intraperitoneally with either cannabidiol (CBD) (0.5, 1, 2, 5, 10, 20 and 40 mg/kg), ∆9 -tetrahydrocannabinol (∆9 -THC; 0.5, 3, 5 and 10 mg/kg) or vehicle 45 min. before exposure to a 10-min. horizontal motion stimulus (amplitude 40 mm, frequency 1 Hz). In further investigations, the CB1 receptor antagonist, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1Hpyrazole-3-carboxamide (AM 251; 5 mg/kg), was injected 15 min. prior to an injection of ∆9 -THC (3 mg/kg). The motion stimulus was applied 45 min. later. The number...

The effect of the plant-derived nonpsychotropic cannabinoid, cannabidiol (CBD), on the function of hydroxytryptamine (5-HT)3A receptors expressed in Xenopus laevis oocytes was investigated using two-electrode voltage-clamp techniques. CBD reversibly inhibited 5-HT (1 M)-evoked currents in a concentration-dependent manner (IC50 0.6 M). CBD (1 M) did not alter specific binding of the 5-HT3A antagonist [3 H]3-(5-methyl-1H-imidazol-4-yl)-1-(1-methylindol-3-yl)propan-1-one (GR65630), in oocytes expressing 5-HT3A receptors. In the presence of 1 M CBD, the maximal 5-HT-induced currents were also inhibited. The EC50 values were 1.2 and 1.4 M, in the absence and presence of CBD, indicating that CBD acts as a noncompetitive antagonist of 5-HT3 receptors. Neither intracellular BAPTA...