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Enhancement of Brain Dopamine Metabolism by Tyrosine During Immobilisation: An In Vivo Study Using Repeated Cerebrospinal Fluid Sampling in Conscious Rats
Author(s) -
Marcou M.,
Kennett G. A.,
Curzon G.
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb05653.x
Subject(s) - metabolite , neurochemical , cisterna magna , homovanillic acid , tyrosine , chemistry , dopamine , 3,4 dihydroxyphenylacetic acid , endocrinology , medicine , metabolism , cerebrospinal fluid , biogenic amine , 5 hydroxyindoleacetic acid , microdialysis , serotonin , biochemistry , central nervous system , neurotransmitter , biology , receptor
Central dopamine (DA) and 5‐hydroxytrypta‐mine (5‐HT) metabolism was monitored in conscious, freely moving rats by determination of levels of the DA metabolites 3,4‐dihydroxyphenylacetic acid (DOPAC) and ho‐movanillic acid (HVA) and the 5‐HT metabolite 5‐hydroxy‐indoleacetic acid (5‐HIAA) in CSF samples withdrawn repeatedly from the cisterna magna and treated with acid to hydrolyse DOPAC and HVA conjugates. The effect of tyrosine on DA metabolism was investigated. Time courses of metabolite concentrations in individual rats in a quiet room showed that tyrosine (20, 50, or 200 mg/kg i.p.) was without significant effect; brain changes were essentially in agreement. However, the increases of CSF DOPAC and HVA levels that occurred on immobilisation for 2 h were further enhanced by tyrosine (200 mg/kg). The associated increases of 5‐HIAA level were unaffected. The corresponding increases of DA metabolite concentrations in the brains of immobilised rats given tyrosine were less marked than the CSF changes and only reached significance for “rest of brain” DOPAC. The CSF studies revealed large interindividual variation in the magnitude and duration of the effects of immobilisation on transmitter amine metabolism. These results may help toward the elucidation of possible relationships between the neurochemical and behavioural effects of stress.