Effect of subchronic administration of tolcapone on L-DOPA-and carbidopa-induced release of striatal dopamine and its metabolites

Abstract

Effect of tolcapone (30 mg/kg), a catechol-O-methyltransferase (COMT) inhibitor, on the release of striatal dopamine and its metabolites induced by L-DOPA and carbidopa is studied in freely moving rats by brain microdialysis. It is shown that inhibition of COMT induced by single injection of tolcapone leads to pronounced shifts in the concentration of metabolites, the concentration of dopamine being unchanged. The preparation stimulated the release of the neurotransmitter induced by combined administration of L-DOPA (50 mg/kg) and carbidopa (50 mg/kg). Maximum efficiency of this combination is attained upon subchronic administration.