Effects of 5-HT3, D-1 and D-2 receptor antagonists on ethanol- and cocaine-induced locomotion

The effects of acute treatment with 5-HT3 receptor antagonists, ondansetron and ICS 205-930, on the stimulation of activity induced by ethanol- 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, in 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 antagonized the stimulation of LMA induced by ethanol. Similar dose of SCH23390, but not spiperone, blocked the stimulation of activity induced by cocaine. 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) 1997 Elsevier Science Inc.