EFFECT OF A SELECTIVE MAO-A INHIBITOR (RO-41-1049) ON STRIATAL L-DOPAAND DOPAMINE METABOLISM - AN IN-VIVO STUDY

We administered Ro 41-1049, an inhibitor of the enzyme monoamine oxida se type A (MAO-A) to rats and monitored extracellular catecholamine le vels in the corpus striatum before and after the intraperitoneal (IP) administration of a bolus of L-dopa. Acute administration of Ro 42-104 9 (1-50 mg/kg IP) produced a dose-dependent decrease in basal levels o f the dopamine metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and an increase in basal levels of dopamine. I n rats treated with Ro 42-1049 (20 mg/kg IP), L-dopa administration (1 00 mg/kg IP) produced a greater increase in striatal levels of dopamin e than it did in controls, while DOPAC and HVA formation was attenuate d. We conclude that inhibition of central MAO-A activity promotes syna ptic accumulation of dopamine following administration of pharmacologi cal doses of L-dopa.