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Tyrosine - Effects on catecholamine releaseTyrosine administration elevates striatal levels of dopamine metabolites in animals given treatments that accelerate nigrostriatal firing, but not in untreated rats. We examined the possibility that the amino acid might actually enhance dopamine release in untreated animals, but that the technique of measuring striatal dopamine metabolism was too insensitive to demonstrate such an effect. Dopamine release was assessed directly, using brain microdialysis of striatal extracellular fluid. Tyrosine administration (50-200 mg/kg IP) did indeed cause a dose related increase in extracellular fluid dopamine levels with minor elevations in levels of DOPAC and HVA, its major metabolites, which were not dose-related. The rise in dopamine was short-lived, suggesting that receptor-mediated feedback mechanisms responded to the increased dopamine release by diminishing neuronal firing or sensitivity to tyrosine. These observations indicate that measurement of changes in striatal DOPAC and HVA, if negative, need not rule out increases in nigrostriatal dopamine release.
Document ID
19930049041
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Acworth, Ian N.
(NASA Headquarters Washington, DC United States)
During, Matthew J.
(NASA Headquarters Washington, DC United States)
Wurtman, Richard J.
(MIT Cambridge, MA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Brain Research Bulletin
ISSN: 0361-9320
Subject Category
Life Sciences (General)
Accession Number
93A33038
Distribution Limits
Public
Copyright
Other

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