Antipsychotic drugs induce similar effects on the release of dopamine and noradrenaline in the medial prefrontal cortex of the rat brain

In the present study we have compared the effects of the classical antipsyc hotic drug haloperidol and four different atypical antipsychotics (clozapin e, risperidone, olanzapine, ziprasidone) on extracellular levels of dopamin e and noradrenaline in the medial prefrontal cortex (MPFC) of conscious rat s. Haloperidol(10, 100 and 800 nmol/kg), clozapine (0.3, 1, 10 and 30 mu mo l/kg), risperidone (100 500 and 5000 nmol/kg), olanzapine (10, 100 and 500 nmol/kg) and ziprasidone (10, 100 and 1000 nmol/kg) were administered subcu taneously to rats. All compounds induced increases in dialysate levels of d opamine and noradrenaline in the medial prefrontal cortex. The increases in duced by the four antipsychotic agents in extracellular levels of dopamine and noradrenaline displayed a striking co-variation both in dose and time. A similar cc-variation was seen in the decrease of dopamine and noradrenali ne, after administration of a low dose (30 nmol/kg, s.c.) of the dopamine D -2/3 receptor agonist (+)-7-hydroxy-2-(N,N-di-n-propylamino) tetralin ((+)- 7-OH-DPAT). It is concluded that there is a close coupling between the rele ase of dopamine and noradrenaline in the medial prefrontal cortex. The mech anism of action of this interaction, that might be of importance for a bett er understanding of the mechanism of action of antipsychotic drugs, is disc ussed. (C) 1998 Elsevier Science B.V. All rights reserved.