Stereoisomers of the atypical neuroleptic carbidine modulate striatal dopamine release in awake rats.

Intracerebral microdialysis was used to monitor extracellular levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid and homovanillic acid in awake rats, after intraperitoneal administration of the cis- and trans-isomers (25 mg/kg and 1 mg/kg, respectively) of carbidine, the atypical neuroleptic drug, in comparison with sulpiride (50 mg/kg) and haloperidol (1 mg/kg). Trans-carbidine was found to be more potent than the cis-isomer in increasing the release of DA. In contrast to sulpiride and haloperidol, both isomers at the doses used, produced only a moderate elevation in the levels of the metabolites of DA. Transcarbidine seemed to be more potent as a neuroleptic drug, in comparison with the cis-isomer.