Haloperidol differentially affects reinforcement and motivational processes in rats running an alley for intravenous heroin.
The role of drug-paired environmental stimuli in opiate self-administration was investigated by exposing animals to discrete cues that were predictive of the availability or unavailability of heroin reinforcement. Rats were trained to traverse a straight arm runway for a reinforcement consisting of a single 0.1 mg/kg intravenous infusion of heroin delivered upon entrance to the goal box. On each trial, one of two discriminative olfactory stimuli (orange and almond) was used: one which signaled the availability of heroin in the goal box (S+), and one which signaled its absence (S-). The effect of dopamine (DA) receptor antagonism on reinforcement and motivational processes was investigated by pretreating subjects with 0.0, 0.15 or 0.30 mg/kg of the DA receptor antagonist drug, haloperidol. Haloperidol had no effect on operant runway performance (i.e. goal time) in any condition. However, 24 h later, on the first post-treatment trial, those haloperidol animals that received heroin in the goal box on the previous trial (i.e. the S+ condition) ran reliably more slowly than subjects that received vehicle on the previous S+ trial. These results suggest that haloperidol does not affect the motivational properties of stimuli which predict the availability of heroin, while it does diminish the reinforcing effects of actually receiving heroin.
McFarland
K
K
Department of Psychology, University of California, Santa Barbara 93106 USA.
Ettenberg
A
A
D000704:Analysis of Variance; D000818:Animals; D004193:Discrimination Learning; D018492:Dopamine Antagonists / Q000494:pharmacology*; D006220:Haloperidol / Q000494:pharmacology*; D003932:Heroin / Q000037:antagonists & inhibitors; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D012646:Self Administration; D012903:Smell; D015819:Substance Abuse, Intravenous / Q000523:psychology*
D018492:Dopamine Antagonists; D009292:Narcotic Antagonists; D003932:Heroin; D006220:Haloperidol