Antiemetic Effects of Serotonergic 5-HT1A-Receptor Agonists in Suncus Murinus

The antiemetic effects of six serotonergic 5-HT1A-receptor agonists, 8-hydroxy-2-(di-n-propylamino)tetrarin (8-OH-DPAT), 4-(4-[4-(2-pyrimidinyl)piperazin-1-yl]butyl)-2,3,4,5- tetrahydro-1,4-benzoxazepine-3,5-dione (SUN8399), buspirone, gepirone, ipsapirone and tandospirone, against motion sickness were investigated in Suncus murinus. Subcutaneous injection of all six agonists completely and dose-dependently suppressed motion-induced emesis. Pretreatment with 8-OH-DPAT or SUN8399 dose-dependently inhibited emesis elicited by nicotine (4.0 mg/kg, s.c.), veratrine (0.7 mg/kg, s.c.), cisplatin (20 mg/kg, i.p.) and copper sulfate (40 mg/kg, p.o.). These results suggest that serotonergic 5-HT1A-receptor agonists are effective as anti-motion sickness drugs, and these drugs may block a common mechanism(s) for the emetic reflex of the suncus because the antiemetic effects of the 5-HT1A-receptor agonists were exerted irrespective of the stimulus.