Catechol-O-methyltransferase inhibition increases striatal L-dopa and dopamine: an in vivo study in rats.
We administered Ro 40-7592, an inhibitor of the enzyme catechol-O-methyltransferase (COMT) that crosses the blood-brain barrier, to rats and monitored extracellular catecholamine levels in the corpus striatum before and after the intraperitoneal administration of a bolus of l-dopa. Acute administration of Ro 40-7592 increased basal levels of l-dopa and dihydroxyphenylacetic acid (DOPAC) and decreased basal homovanillic acid (HVA) levels, but did not affect basal dopamine levels. In rats treated with Ro 40-7592, l-dopa administration produced a greater increase in striatal levels of l-dopa, dopamine, and DOPAC than it did in controls, while HVA formation was attenuated. We conclude that inhibition of COMT activity promotes central dopamine synthesis and release following administration of pharmacologic doses of l-dopa.
Brannan
T
T
Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029.
Martínez-Tica
J
J
Yahr
M D
MD
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001577:Benzophenones / Q000494:pharmacology*; D065098:Catechol O-Methyltransferase Inhibitors; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D006719:Homovanillic Acid / Q000378:metabolism; D007980:Levodopa / Q000378:metabolism*; D008297:Male; D009596:Nitrophenols; D051381:Rats; D011919:Rats, Inbred Strains; D000077867:Tolcapone
D001577:Benzophenones; D065098:Catechol O-Methyltransferase Inhibitors; D009596:Nitrophenols; D015102:3,4-Dihydroxyphenylacetic Acid; D007980:Levodopa; D000077867:Tolcapone; D004298:Dopamine; D006719:Homovanillic Acid