nitecapone and levodopa-methyl-ester

A new COMT inhibitor, nitecapone (OR-462) or clorgyline, a MAO-A inhibitor, was infused into the 3rd brain ventricle (i.c.v.) of conscious male rats. None of the enzyme inhibitors given alone alter hypothalamic or striatal levels of L-dopa, dopamine or their metabolites. Most of the rats were pretreated with levodopa/carbidopa (LD/CD, 15/30 mg kg-1 intraperitoneally). Now, the action of nitecapone is localized in the hypothalamus since homovanillic acid (HVA) is decreased there, not in the striatum. The levels of 3-O-methyldopa (3-OMD) are not changed in either brain region, suggesting a lack of the peripheral leakage of nitecapone. Clorgyline (3 and 10 micrograms rat-1) elevates hypothalamic and dopamine levels. Nitecapone and clorgyline decrease prolactin (PRL) levels below those reduced by LD/CD treatment.

Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Brain; Carbidopa; Catechols; Cerebral Ventricles; Clorgyline; Corpus Striatum; Dopamine; Homovanillic Acid; Hypothalamus; Injections, Intraventricular; Levodopa; Male; Pentanones; Prolactin; Rats; Rats, Wistar; Thyrotropin