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  • Parkinson's disease  (4)
  • 1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline  (1)
  • 6,7-dihydroxytetra-hydroisoquinolines  (1)
  • Keywords: 1(N)-Amino-4-phenyl-1  (1)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    A new metabolic pathway of L-threo-3,4-dihydroxyphenylserine, a precursor amino acid of norepinephrine, in the brain Studies by in vivo microdialysis (1994)
    Springer
    Journal of neural transmission 7 (1994), S. 21-33 
    Details
    ISSN: 1435-1463
    Keywords: L-threo-3,4-dihydroxyphenylserine ; DOPS-aldolase ; norepinephrine ; supplement therapy ; Parkinson's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The metabolism and the effects of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) were studied in the rat brain striatum by in vivo microdialysis. In the brain L-threo-DOPS was metabolized by 3 different enzymes; aromatic L-amino acid decarboxylase, catechol-O-methyltransferase, and DOPS-aldolase. DOPS-aldolase was the main enzyme which metabolizes L-threo-DOPS. The amounts of the metabolites by L-amino acid decarboxylase (norepinephrine and its metabolites) were 0.4% of the total amounts of metabolites detected in the dialysate, while those by catechol-O-methyltransferase, 2.1%, and by DOPS-aldolase, 97.5%, after 100 min perfusion of L-threo-DOPS. L-threo-DOPS was found to increase extracellular levels of dopamine and serotonin, and to inhibit monoamine catabolism in the brain. Inhibition of DOPS-aldolase should improve its effectiveness as the supplement therapy of norepinephrine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02252660
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  • 2
    Electronic Resource
    Electronic Resource
    Stereospecific occurrence of a parkinsonism-inducing catechol isoquinoline, n-methyl(R)salsolinol, in the human intraventricular fluid (1996)
    Springer
    Journal of neural transmission 103 (1996), S. 1069-1076 
    Details
    ISSN: 1435-1463
    Keywords: Parkinson's disease ; neurotoxin ; dopamine ; intraventricular fluid ; N-methylsalsolinol ; catechol isoquinolinium ion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N-Methyl(R)salsolinol, an endogenous neurotoxin, has been proposed to be closely involved in the pathogenesis of Parkinson's disease. The selective toxicity to dopaminergic neurons was strictly limited for (R)-enantiomer of N-methylsalsolinol. Its precursor, (R)salsolinol was enzymatically synthesized from dopamine and acetaldehyde in human. However, it has never been examined whether a non-enzymatic reaction produces racemic salsolinol derivatives from dopamine especially in patients under L-DOPA therapy. To clarify the point, their contents were examined in intraventricular fluid from parkinsonian patients administrated with L-DOPA. Only (R)-enantiomer of N-methylsalsolinol and very low concentration of salsolinol could be detected. The results suggest that N-methyl(R)salsolinol synthesis may not depend on dopamine level, but on the activity of enzymes related to its synthesis and/or catabolism. The results are discussed in relation to pathogenesis Parkinson's disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291791
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation of 1-amino-4-phenyl-1,2,3,6-tetrahydropyridine, a 1-amino analog of MPTP, by type A and B monoamine oxidase (1998)
    Springer
    Journal of neural transmission 105 (1998), S. 1253-1264 
    Details
    ISSN: 1435-1463
    Keywords: Keywords: 1(N)-Amino-4-phenyl-1 ; 2 ; 3 ; 6-tetrahydropyridine ; oxidation ; monoamine oxidase ; MPTP ; MPP+ ; human brain synaptosomes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. A 1-amino analog of MPTP, 1(N)-amino-4-phenyl-1,2,3,6-tetrahydropyridine, was synthesized and the oxidation was examined using human synaptosomal mitochondria as sources of type A and B monoamine oxidase. An oxidation product, 1-amino-4-phenylpyridinium ion, was quantified by high-performance liquid chromatography-fluorometric detection. The amino analog was a substrate of both type A and B monoamine oxidase and the oxidation depended linearly on the enzyme amount and the reaction time with an optimal pH around 7.5. After the systemic injection of the amino analog in C57/black mice for one week, 1-amino-4-phenylpyridinium ion was detected in the brain. 1(N)-Amino-4-phenyl-1,2,3,6-tetrahydropyridine was proved to be cytotoxic to pheochromocytoma PC12 cells, and it may be a new neurotoxin bioactivated through the oxidation by type A and B monoamine oxidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007020050128
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  • 4
    Electronic Resource
    Electronic Resource
    Naturally-occurring isoquinolines perturb monoamine metabolism in the brain: studied by in vivo microdialysis (1993)
    Springer
    Journal of neural transmission 94 (1993), S. 91-102 
    Details
    ISSN: 1435-1463
    Keywords: Tetrahydroisoquinolines ; monoamine oxidase ; catechol-O-methyl-transferase ; monoamines ; rat striatum ; in vivo microdialysis ; Parkinson's disease ; alcoholism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Naturally occurring isoquinolines affected the monoamine metabolism in the rat striatum, as proved by in vivo microdialysis technique. By analysis of monoamines and their metabolites in the dialysate, dopamine-derived 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines were found to inhibit monoamine oxidase and catechol-O-methyltransferase activity. 1-Methyl- and 2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline were found to inhibit activity of type A monoamine oxidase most markedly. To compare the structure-activity relationship, corresponding isoquinolines without a catechol structure were also examined. The inhibition by catechol isoquinolines was more manifest than those without a catechol structure. Among latter isoquinolines, N-methyl-isoquinolinium ion was the most potent inhibitor of monoamine oxidase. In addition, catechol isoquinolines increased monoamine levels in the brain. The number and the site of the methyl group are essentially required for the inhibition of monoamine oxidase and a catechol structure for that of catechol-O-methyl-transferase. These results are discussed in relation to possible involvement of these isoquinolines to the clinical features of some neuro-psychiatric diseases, such as alcoholism or in L-DOPA therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245003
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  • 5
    Electronic Resource
    Electronic Resource
    Uptake of a neurotoxin-candidate, (R)-1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline into human dopaminergic neuroblastoma SH-SY5Y cells by dopamine transport system (1994)
    Springer
    Journal of neural transmission 98 (1994), S. 107-118 
    Details
    ISSN: 1435-1463
    Keywords: Uptake ; inhibition ; dopamine transporter ; 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline ; 1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline ; 1,2-dimethyl-6,7-dihydroxyisoquinolinium ion ; neuroblastoma SH-SY5Y cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Uptake of catechol isoquinolines to dopamine cells was studied using human dopaminergic neuroblastoma SH-SY5Y cells. Only (R)-1,2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-1,2-DiMeDHTIQ] was transported by dopamine uptake system, while (S)-1,2-DiMeDHTIQ, (R)- and (S)-1-methyl-6,7-dihydroxy-tetrahydroisoquinoline, and 1,2-dimethyl-6,7-dihydroxyisoquinolinum ion were not. Kinetical study showed that the uptake of (R)-1,2-DiMeDHTIQ followed the Michaelis-Menten equation, and the values of the Michaelis constant and the maximal velocity were obtained to be 102.6 ± 36.9 μM and 66.0 ± 2.8 pmol/min/mg protein. Dopamine was found to inhibit (R-1-DiMeDHTIQ uptake competitively. These results suggest that the selective uptake by dopamine transporter may account for the specific neurotoxicity of (R)-1,2-DiMeDHTIQ to dopamine neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277014
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  • 6
    Electronic Resource
    Electronic Resource
    The mechanism of perturbation in monoamine metabolism by L-DOPA therapy: in vivo and in vitro studies (1992)
    Springer
    Journal of neural transmission 90 (1992), S. 183-197 
    Details
    ISSN: 1435-1463
    Keywords: L-DOPA therapy ; Parkinson's disease ; 3-O-methyl-DOPA ; tyrosine hydroxylase ; tryptophan hydroxylase ; biopterin cofactor ; allosteric effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the cerebrospinal fluid of the patients with Parkinson's disease treated with L-DOPA, L-3-O-methyldopa was the major metabolite of administered L-DOPA. Using a dopaminergic cell model, clonal rat phenochromocytoma PC 12h cells, and by microdialysis of the rat striatum it was proved that L-3-O-methyldopa was taken up into monoamine neurons by transport system specific for aromatic L-amino acids and inhibited transport of L-DOPA and other amino acids competitively. L-3-O-Methyldopa depleted allosteric regulation of the biopterin cofactor on activity of tyrosine hydroxylase, the rate-limiting enzyme of catecholamine synthesis. Depletion of the allostery may perturb the buffer action of endogenous L-DOPA synthesis that stabilizes dopamine level in the brain. By these mechanisms L-3-O-methyldopa may reduce clinical effectiveness of administrated L-DOPA and be involved in wearing-off phenomenon. L-DOPA inhibited the activity of tryptophan hydroxylase and thus serotonin synthesis, which may be related to psychiatric side-effects in the patients under L-DOPA therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01250960
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  • 7
    Electronic Resource
    Electronic Resource
    Inhibition of type A and B monoamine oxidase by 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines and their N-methylated derivatives (1993)
    Springer
    Journal of neural transmission 92 (1993), S. 125-135 
    Details
    ISSN: 1435-1463
    Keywords: Type A and B monoamine oxidase ; inhibitors ; 6,7-dihydroxytetra-hydroisoquinolines ; salsolinols ; human brain synaptosomal mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 6,7-Dihydroxy-1,2,3,4-tetrahydroisoquinoline (norsalsolinol) and 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol), and their N-methylated derivatives were found to inhibit type A and B monoamine oxidase isolated from human brain synaptosomal mitochondria. N-Methyl-norsalsolinol, (R) and (S) enantiomer of salsolinol, and N-methyl-salsolinols inhibited type A monoamine oxidase competitively to the substrate, kynuramine, andR enantiomers were more potent inhibitors thanS enantiomers. The inhibition was reversible. Norsalsolinol induced positive cooperativity toward kynuramine. Both norsalsolinol and N-methyl-norsalsolinol inhibited type B oxidase non-competitively to the substrate, and their K1 values were much higher than those to type A. Types of inhibition of type A monoamine oxidase depended on the enzyme sources. Inhibition of monoamine oxidase by 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines is discussed in relation to their chemical structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244872
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