Influence of L-3-methoxytyrosine on monoamine synthesis in rat brain.
Rats were injected i.p. with L-3-methoxytyrosine, 100 or 300 mg/kg. One h later brain, liver, heart and blood plasma were analyzed for catecholamines and their precursors. In brain Dopa as well as dopamine and noradrenaline levels were unchanged, while demethylation of L-3-methoxytyrosine might have occurred in peripheral organs since Dopa levels in liver and dopamine in heart were elevated. 3-Methoxytyramine could not be detected in brain and liver after treatment with L-3-methoxytyrosine. Monoamine synthesis in vivo was measured in whole brain by determining the accumulation of Dopa and 5-hydroxytryptophan 30 min after the i.p. injection of NSD 1015(3-hydroxybenzylhydrazine HC1, 100 mg/kg), an inhibitor of the aromatic amino acid decarboxylase. L-3-Methoxytyrosine attenuated the formation of Dopa and 5-hydroxytryptophan by about 25% in brain tissue. The effect was paralleled by a decrease in the brain concentration of tryptophan.
D006916:5-Hydroxytryptophan / Q000096:biosynthesis; D000818:Animals; D001679:Biogenic Amines / Q000096:biosynthesis*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004295:Dihydroxyphenylalanine / Q000096:biosynthesis; D004298:Dopamine / Q000096:biosynthesis; D006834:Hydrazines / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000096:biosynthesis; D007980:Levodopa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000096:biosynthesis; D051381:Rats; D012701:Serotonin / Q000096:biosynthesis; D014364:Tryptophan / Q000096:biosynthesis; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000494:pharmacology
D001679:Biogenic Amines; D006834:Hydrazines; D012701:Serotonin; D014443:Tyrosine; D007980:Levodopa; D006897:Hydroxyindoleacetic Acid; D004295:Dihydroxyphenylalanine; D014364:Tryptophan; C004297:3-hydroxybenzylhydrazine; D006916:5-Hydroxytryptophan; D004298:Dopamine; D009638:Norepinephrine