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Neurotransmitter metabolites, Urinary

Urinary Neurotransmitter Metabolites in Drug-Free Chronic Schizophrenic Patients Measured by Gas Chromatography Selected Positive Ion Monitoring... [Pg.65]

Peripheral Dopaminergic System Dopamine is usually thought of as a neurotransmitter in the brain or as an intermediate in the production of norepinephrine and epinephrine in the periphery. It has been presumed tliat these sources account for the large amounts of dopamine and dopamine metabolites excreted in urine. The contribution of the brain to circulating levels and urinary excretion of dopamine metabolites is, however, now known to be relatively minor. Also, in sympathetic nerves and the adrenal medulla most dopamine is converted to norepinephrine. Therefore other sources and functions of dopamine in the periphery must be considered. Emerging evidence suggests the presence of a third peripheral catecholamine system, in which dopamine functions not as a neurotransmitter or circulating hormone, but as an autocrine or paracrine substance. ... [Pg.1044]

Measurement of altered levels of dopamine and other neurotransmitters in the basal ganglia has proven to be a useful means of evaluating central nervous system effects in animals (e.g., Bonilla and Prasad 1984 Eriksson et al. 1987a, 1987b), and these changes are often observed before any behavioral or motor effects are apparent (Bird et al. 1984). No noninvasive methods are currently available to determine whether there are decreased dopamine levels in the brain of exposed humans, but decreased urinary excretion of dopamine and its metabolites has been noted in groups of manganese-exposed workers (Bernheimer et al. 1973 ... [Pg.319]

Effect. No reliable biomarkers of manganese effect are known. Biochemical changes such as altered blood or urinary levels of steroids, neurotransmitters, or their metabolites are plausible biomarkers of exposure, but this possibility has not been thoroughly investigated. Although methods exist for the analysis of these biochemicals, further work to improve the analyses does not seem warranted unless the utility of this approach is established. [Pg.427]

Catecholamines and their metabolites The catecholamines, adrenaline, noradrenaline, and dopamine are essential components of the central nervous system acting as neurotransmitters both within the brain and at peripheral nerves. All are synthesized in the adrenal medulla from phenylalanine or tyrosine and are metabolized by a mixture of enzymatic side chain oxidation and methylation of the hydroxy groups on the ring. If the metabolism is complete, adrenaline and noradrenaline are degraded to 4-hydroxy-3-methoxy mandelic acid (HMMA, commonly called vanillylmandelic acid - VMA), while dopamine is broken down to homovanillic acid (HVA). Urinary excretion of these metabolites and their conjugates is the major route of elimination of catecholamines from the body, although small amounts are excreted unchanged as the free catecholamines. [Pg.2699]


See other pages where Neurotransmitter metabolites, Urinary is mentioned: [Pg.711]    [Pg.345]    [Pg.50]    [Pg.1459]    [Pg.21]    [Pg.228]   
See also in sourсe #XX -- [ Pg.99 ]




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