Effects of Chronic Haloperidol and Intermittent Cocaine Administration on Behavior Elicited by Apomorphine

Relatively little is known about the behavioral or neurophysiological effects resulting from the concurrent administration of haloperidol and cocaine. To investigate this drug interaction, the effects of chronic, daily administration of haloperidol, intermittent cocaine injections, or the combination of both drug treatments on locomotion and stereotypy elicited by apomorphine in rats ( Rattus norvegicus ) were compared. The results indicated that, in comparison to treatment with either drug alone, the combination of daily haloperidol and intermittent injections of cocaine produced unique behavioral effects. Rats coadministered both drugs exhibited significant increases in apomorphine-induced locomotion that were maintained throughout the 64 days following suspension of drug treatment. These results are discussed in terms of the possible neurophysiological mechanisms underlying the observed behavioral changes and are related to the consequences of psychostimulant abuse in human neuroleptic treated populations.