Amphetamine-like discriminative stimulus effects of ephedrine and its stereoisomers in pigeons

This study assessed the discriminative stimulus effects of (+/-)-ephedrine and its stereoisomers in pigeons discriminating 1.0 mg/kg of amphetamine from saline. Amphetamine, (+/-)-, (-)-, and (+)-ephedrine, and cocaine occasioned greater than 80% drug-key responding with the following rank order of potency: amphetamine > cocaine greater than or equal to (+/-)-ephedrine greater than or equal to (+/-)-ephedrine greater than or equal to (+)-ephedrine. Neither the alpha-adrenergic antagonist, phentolamine, nor the beta-adrenergic antagonist, propranolol, antagonized the effects of amphetamine or ()-ephedrine. In contrast, the dopamine receptor antagonist, haloperidoi, antagonized the discriminative stimulus effects of amphetamine and (+/-)-ephedrine as well as those of (-)- and (+/-)-ephedrine. These results indicate that, like cocaine, ( -)-ephedrine and its stereoisomers share discriminative stimulus effects with amphetamine. Moreover, these effects appear to be the result of increased activity in dopaminergic systems.