The effect of the 5-HT_1A receptor agonist, 8-OH-DPAT, on motion-induced emesis in Suncus murinus

In the present study we evaluated the role of 5-HT_1A receptors in mediating the inhibitory action of 8-OH-DPAT, a 5-HT_1A receptor agonist, in motion sickness in Suncus murinus. 8-OH-DPAT (0.1 mg/kg, i. p) attenuated motion-induced emesis which was associated with an increase in the latency of the onset to the first emetic episode. Pre-treatment with methysergide (a 5-HT_1/2/7 receptor antagonist, 1.0 mg/kg, i. p.), WAY-100635 (a 5-HT_1A receptor antagonist, 1.0 mg/kg, i. p.), SB269970A (a 5-HT₇ receptor antagonist, 1.0 and 5.0 mg/kg, i. p.), ondansetron (a 5-HT₃ receptor antagonist, 1.0 mg/kg, i. p) or GR13808 (a 5-HT₄ receptor antagonist, 0.5 mg/kg, i. p) failed to modify the inhibitory action of 8-OH-DPAT on motion sickness. Furthermore, the application of either methysergide, WAY-100635, SB269970A, ondansetron or GR13808 alone had no effect on motion sickness in its own right. These data indicate that neither 5-HT_1A nor any 5-HT₂ receptor subtypes, 5-HT₃, 5-HT₄ and 5-HT₇ receptors are likely to be involved in the inhibition of motion-induced emesis mediated by 8-OH-DPAT.