EFFECTS OF 5-HT3, D-1 AND D-2 RECEPTOR ANTAGONISTS ON ETHANOL-INDUCEDAND COCAINE-INDUCED LOCOMOTION

The effects of acute treatment with 5-HT3 receptor antagonists, ondans etron and ICS 205-930, on the stimulation of activity induced by ethan ol- and cocaine were examined. Ethanol (1.8 or 2 g/kg i.p.) or cocaine (15 mg/kg i.p.) produced a significant increase in locomotor activity (LMA) in DBA/2N mice. Pretreatment with ondansetron or ICS 205-930, i n doses ranging from 0.001 to 0.1 mg/kg (s.c), did not modify ethanol or cocaine induced stimulation of activity. In contrast, pretreatment with a 10 mu g/kg dose of either SCH 23390 or spiperone, a D-1 and D-2 dopamine (DA) receptor antagonist respectively, completely antagonize d the stimulation of LMA induced by ethanol. Similar dose of SCH23390, but not spiperone, blocked the stimulation of activity induced by coc aine. These results indicate that D-1 but not D 2 DA receptors play a significant role in cocaine induced hyperactivity whereas both D-1 and D 2 are involved the locomotor activating effects of ethanol. (C) 199 7 Elsevier Science Inc.