EFFECTS OF PRAZOSIN ON THE DOPAMINERGIC NEUROTRANSMISSION IN RAT-BRAIN

Effects of systemic and local administration of prazosin, an alpha(1)- adrenoceptor antagonist, on dopaminergic neurotransmission in the caud ate putamen and nucleus accumbens were characterized in microdialysis experiments. Prazosin (10 mg/kg s.c.) resulted in blood pressure reduc tion, however, did not alter dopamine release in the two examined brai n areas. In contrast, local administration of prazosin (10 mu M) via t he microdialysis probe resulted in a clear attenuation of dopamine out put, indicating that tonically activated alpha(1)-adrenoceptors stimul ate dopamine release in the caudate putamen as well as in the nucleus accumbens. The relevance of this finding for antipsychotics exhibiting antagonism at alpha(1)-adrenoceptors is discussed.