Dextromethorphan alters the reinforcing effect of cocaine in the rat.
Dextromethorphan (DM) at supra-antitussive doses produces psychotomimetic effects in humans. In order to achieve a better understanding of the pharmacological mechanisms responsible for the behaviors induced by DM, we examined the effects of DM on the intravenous self-administration of cocaine in the rat. The effects of DM (40 mg/kg, p.o.) on responding for 0.5, 0.25, 0.125, 0.06 and 0.03 mg/kg/infusion of cocaine was assessed. DM decreased the rate of responding for higher doses of cocaine (0.5, 0.25 and 0.125 mg/kg/infusion), and increased the rate of responding for lower doses of cocaine (0.06 and 0.03 mg/kg/infusion), suggesting that DM shifted the dose-response curve for cocaine self-administration to the left. Therefore, our results indicate that the sensitivity to cocaine's behavioral effects appears to be enhanced by DM.
Kim
H C
HC
Department of Pharmacy, College of Pharmacy, Kangwon National University, Chunchon, Korea.
Park
B K
BK
Hong
S Y
SY
Jhoo
W K
WK
D000818:Animals; D000996:Antitussive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects*; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D003915:Dextromethorphan / Q000008:administration & dosage / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007262:Infusions, Intravenous; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012646:Self Administration
D000996:Antitussive Agents; D018765:Dopamine Uptake Inhibitors; D003915:Dextromethorphan; D003042:Cocaine