Discriminative properties of l-cathinone compared to dl- and d-cathinone.

Rats were trained to discriminate between the stimulus properties of 0.6 mg/kg l-cathinone and its vehicle in a two-lever, food-motivated operant task. Once trained, rats showed a dose-dependent decrease in discrimination performance with lower l-cathinone doses and analysis of the dose-response relationship indicated an ED50 of 0.19 mg/kg. Administration of either dl-or d-cathinone produced a pattern of discriminative responding similar to l-cathinone with ED50s of 0.29 and 0.63 mg/kg, respectively. Thus, the potency of the racemeric cathinone lies approximately midway between that of the two isomers. Time-course data indicate that l-cathinone has a peak effect at 15-30 min post-administration with a duration of 180 min. Pretreatment with the serotonic receptor blocker pirenperone did not affect l-cathinone discrimination, whereas pretreatment with 0.2 mg/kg haloperidol, a dopamine receptor blocking agent, attenuated the l-cathinone discrimination. These data suggest that the stimulus properties of l-cathinone are possibly mediated by brain dopaminergic systems.