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), yl}-2,3,4,5-tetrahy dro-1,4-benzoxazepine-3,5-dione (SUN8399), buspirone, gepirone, ipsapi rone and tandospirone, against motion sickness were investigated in Su ncus murinus. Subcutaneous injection of all six agonists completely an d dose-dependently suppressed motion-induced emesis. Pretreatment with 8-OH-DPAT or SUN8399 dose-dependently inhibited emesis elicited by ni cotine (4.0 mg/kg, s.c.), veratrine (0.7 mg/kg, s.c.), cisplatin (20 m g/kg, i.p.) and copper sulfate (40 mg/kg, p.o.). These results suggest that serotonergic 5-HT1A-receptor agonists are effective as anti-moti on 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.