Effect of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin and infusion of L-tyrosine on the in vivo L-[beta-11C] DOPA disposition in the monkey brain. 1996

H Tsukada, and K J Lindner, and P Hartvig, and Y Tani, and J Valtysson, and P Bjurling, and T Kihlberg, and G Westerberg, and Y Watanabe, and B Långström
Central Research Laboratory, Hamamatsu Photonics K.K., Shizuoka, Japan.

The effect of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4) and L-tyrosine infusion on [11C]dopamine synthesis was analyzed in the striatum of Rhesus using positron emission tomography (PET). The rate for decarboxylation from L-[beta-11C]DOPA to [11C]dopamine was calculated using a graphical method with cerebellum as a reference region. Although the peripheral administration of 6R-BH4 at low dose (2 mg/kg) did not provide a significant increase in the rate of dopamine biosynthesis, a high dose of 6R-BH4 (20 mg/kg) induced an elevation of the rate. This 6R-BH4-induced elevation of the dopamine synthesis rate was further dose-dependently enhanced by the continuous infusion of L-tyrosine (0.2 and 1.0 mumol/min/kg). L-Tyrosine infusion with a rate of 1.0 mumol/min/kg caused an enhancement of the rate even during low dose administration of 6R-BH4 (2 mg/kg). L-Tyrosine infusion alone did not induce any elevation of the dopamine biosynthesis rate. The analysis of plasma indicated that the metabolic ratios of L-[beta-11C]DOPA to each metabolite were not affected by 6R-BH4 and/or L-tyrosine infusion. The results suggest that the low dose loading of tyrosine facilitates the activity of 6R-BH4 on the presynaptic dopamine biosynthesis, and also that the combined effects can be monitored by PET using L-[beta-11C]DOPA as a biochemical probe.

UI MeSH Term Description Entries
D008253 Macaca mulatta A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans. Chinese Rhesus Macaques,Macaca mulatta lasiota,Monkey, Rhesus,Rhesus Monkey,Rhesus Macaque,Chinese Rhesus Macaque,Macaca mulatta lasiotas,Macaque, Rhesus,Rhesus Macaque, Chinese,Rhesus Macaques,Rhesus Macaques, Chinese,Rhesus Monkeys
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D004295 Dihydroxyphenylalanine A beta-hydroxylated derivative of phenylalanine. The D-form of dihydroxyphenylalanine has less physiologic activity than the L-form and is commonly used experimentally to determine whether the pharmacological effects of LEVODOPA are stereospecific. Dopa,3,4-Dihydroxyphenylalanine,3-Hydroxy-DL-tyrosine,Dihydroxyphenylalanine Hydrochloride, (2:1),beta-Hydroxytyrosine,3 Hydroxy DL tyrosine,3,4 Dihydroxyphenylalanine,beta Hydroxytyrosine
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005260 Female Females
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D000975 Antioxidants Naturally occurring or synthetic substances that inhibit or retard oxidation reactions. They counteract the damaging effects of oxidation in animal tissues. Anti-Oxidant,Antioxidant,Antioxidant Activity,Endogenous Antioxidant,Endogenous Antioxidants,Anti-Oxidant Effect,Anti-Oxidant Effects,Anti-Oxidants,Antioxidant Effect,Antioxidant Effects,Activity, Antioxidant,Anti Oxidant,Anti Oxidant Effect,Anti Oxidant Effects,Anti Oxidants,Antioxidant, Endogenous,Antioxidants, Endogenous
D001708 Biopterins Pterin derivatives based on 2-amino-6-(1,2-dihydroxypropyl)-4(1H)-pteridinone. Biopterins are natural products that have been considered as growth factors for some insects. Biopterins are cofactors for the AROMATIC AMINO ACID hydroxylases and NITRIC OXIDE SYNTHASE. Deficiencies in BIOPTERINS metabolism (e.g., lowered TETRAHYDROBIOPTERIN) are associated with neurological deterioration (e.g., HYPERPHENYLALANINAEMIA). 2-Amino-6-((1S,2R)-1,2-dihydroxypropyl)-4(1H)-pteridinone,2-Amino-6-((1S,2S)-1,2-dihydroxypropyl)-4(1H)-pteridinone,2-Amino-6-(1,2-dihydroxypropyl)-4(8H)-pteridinone,2-amino-6-((1R,2R)-1,2-dihydroxypropyl)-4(3H)-pteridinone,4(1H)-Pteridinone, 2-amino-6-(1,2-dihydroxypropyl)-, (S-(R*,S*))-,6-Biopterin,Biopterin,D-threo-Biopterin,L-Biopterin,L-erythro-Biopterin,L-threo-Biopterin,2-Amino-6-(1,2-dihydroxypropyl)-4(1H)-pteridinone,Dictyopterin,Orinapterin,6 Biopterin,D threo Biopterin,L Biopterin,L erythro Biopterin,L threo Biopterin
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor
D014443 Tyrosine A non-essential amino acid. In animals it is synthesized from PHENYLALANINE. It is also the precursor of EPINEPHRINE; THYROID HORMONES; and melanin. L-Tyrosine,Tyrosine, L-isomer,para-Tyrosine,L Tyrosine,Tyrosine, L isomer,para Tyrosine

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