PHARMACOLOGICAL MODIFICATION OF COCAINE AND APOMORPHINE SELF-ADMINISTRATION IN THE SQUIRREL MONKEY

Abstract Squirrel monkeys with intravenous catheters self-administered apomorphine and piribedil which have relatively specific dopamine agonist activity, as well as cocaine which indirectly activates both dopaminergic and noradrenergic receptors. The frequency of apomorphine and cocaine self-administration increased when the monkeys were pre-treated with low doses of pimozide and chlorpromazine. These increased intakes suggest that the reinforcing effects of cocaine and apomorphine were antagonized by these dopamine blocking agents. Compounds such as chlordiazepoxide and amitriptyline did not affect cocaine self-administration frequency. These findings link dopamine to the reinforcing actions of psychomotor stimulants.