3-Methoxytyramine and different neuroleptics: Dissociation from HVA and DOPAC

The effect of haloperidol and clozapine, a cataleptogenic and a non cataleptogenic neuroleptic, on striatal concentrations of 3-methoxytyramine (3-MT), DOPAC and HVA was studied. The data indicate that 3-MT changes seem to parallel the electrophysiological and behavioral profile of these two neuroleptics. In fact, haloperidol and clozapine, given at doses which elicit a comparable increase of DOPAC and HVA concentrations, affect differently 3-MT content which is increased by haloperidol but not modified by clozapine. Moreover, the results obtained after various lesions which differently affect the integrity of striatal or nigral neuronal organization, seem to suggest that mechanisms localized in the substantia nigra may play an important role in the modulation of the haloperidol induced increase of striatal 3-MT.