FAILURE BY TRICYCLIC ANTIDEPRESSANTS TO AFFECT THE INCREASE OF DOPAMINE EXTRACELLULAR CONCENTRATIONS PRODUCED BY HALOPERIDOL IN THE CAUDATE AND ACCUMBENS NUCLEI OF RATS

The effect of different inhibitors of monoamine uptake on dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) neuronal outflow was studied in the caudate and accumbens nuclei of rats, using the in vivo brain microdialysis method coupled to HPLC electrochemical detection. Under conditions of DA receptor blockade (as produced by the i.p. administration of 0.25 mg/kg of haloperidol), cocaine, GBR-12909 and d-amphetamine increased the concentration of extracellular DA beyond the effect produced by haloperidol alone in both areas studied. GBR-12909 and cocaine also increased DOPAC concentration, while d-amphetamine decreased it. On the contrary, the tricyclic antidepressants (TCA), desipramine and chloripramine, failed to modify the effect of haloperidol on DA and DOPAC neuronal outflow. It was concluded that: (a) noradrenergic and serotonergic nerve terminals do not take up DA released from dopaminergic neurons, and (b) TCA have no effect on dopaminergic terminals.