Dopa Decarboxylase Activity of the Living Human Brain

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 7; pp. 2721 - 2725
• Main Authors: Gjedde, Albert, Reith, Jakob, Dyve, Suzan, Leger, Gabriel, Guttman, Mark, Diksic, Mirko, Evans, Alan, Kuwabara, Hiroto
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.04.1991; National Acad Sciences
• Subjects: 550601 - Medicine- Unsealed Radionuclides in Diagnostics; AMINES; AMINO ACIDS; ANIMALS; AROMATICS; AUTONOMIC NERVOUS SYSTEM AGENTS; BETA DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; Biochemistry and metabolism; Biological and medical sciences; BIOSYNTHESIS; Blood plasma; BODY; BRAIN; Brain - diagnostic imaging; Brain - enzymology; CARBON-CARBON LYASES; CARBOXY-LYASES; CARBOXYLIC ACIDS; CARDIOTONICS; CARDIOVASCULAR AGENTS; Caudate nucleus; CENTRAL NERVOUS SYSTEM; Coefficients; COMPUTERIZED TOMOGRAPHY; DECARBOXYLASES; Decarboxylation; DIAGNOSTIC TECHNIQUES; Dihydroxyphenylalanine - analogs & derivatives; Dihydroxyphenylalanine - metabolism; DOPA; Dopa Decarboxylase - metabolism; DOPAMINE; DRUGS; EMISSION COMPUTED TOMOGRAPHY; ENZYME ACTIVITY; ENZYMES; FLUORINE 18; FLUORINE ISOTOPES; Fluorine Radioisotopes; Fundamental and applied biological sciences. Psychology; HOURS LIVING RADIOISOTOPES; Humans; HYDROXY ACIDS; HYDROXY COMPOUNDS; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; Kinetics; LIGHT NUCLEI; LYASES; Magnetic Resonance Imaging - methods; MAMMALS; MAN; MATHEMATICAL MODELS; Mathematics; Methylation; NERVOUS SYSTEM; NEUROREGULATORS; NUCLEI; ODD-ODD NUCLEI; Organ Specificity; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANS; Oxidases; PHENOLS; POLYPHENOLS; POSITRON COMPUTED TOMOGRAPHY; Positron emission tomography; PRIMATES; Putamen; Radioactive decay; RADIOISOTOPES; RADIOLOGY AND NUCLEAR MEDICINE; Reference Values; SYMPATHOMIMETICS; SYNTHESIS; Tissue samples; TOMOGRAPHY; Tomography, Emission-Computed - methods; VERTEBRATES; Vertebrates: nervous system and sense organs; Human; Brain; In vivo; Dopamine; Enzymatic activity; Distribution; Central nervous system; Aromatic-L-amino-acid decarboxylase; Positron emission tomography
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.7.2721

Monoaminergic neurons use dopa decarboxylase (DDC; aromatic-L-amino-acid carboxy-lyase, EC 4.1.1.28) to form dopamine from L-3,4-dihydroxyphenylalanine (L-dopa). We measured regional dopa decarboxylase activity in brains of six healthy volunteers with 6-[18F]fluoro-L-dopa and positron emission tomography. We calculated the enzyme activity, relative to its Km, with a kinetic model that yielded the relative rate of conversion of 6-[18F]fluoro-L-dopa to [18F]fluorodopamine. Regional values of relative dopa decarboxylase activity ranged from nil in occipital cortex to 1.9 h-1in caudate nucleus and putamen, in agreement with values obtained in vitro.