Hc. Kim et al., DEXTROMETHORPHAN ALTERS THE REINFORCING EFFECT OF COCAINE IN THE RAT, Methods and findings in experimental and clinical pharmacology, 19(9), 1997, pp. 627-631
Dextromethorpohan (DM) at supra-antitussive doses produces psychotomin
etic effects in humans. In order to achieve a better understanding of
the pharmacological mechanisms responsible for the behaviors induced b
y DM, we examined the effects of DM on rile intravenous self-administr
ation of cocaine in the rat. The effects of DM (40 mg/kg, p. o.) on re
sponding 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 tile
sensitivity to cocaine's behavioral effects appears to be enhanced by
DM.