Tyrosine availability modulates potassium-induced striatal catecholamine efflux in vivo.
Brain Res
; 1209: 74-84, 2008 May 13.
Article
in En
| MEDLINE
| ID: mdl-18400209
ABSTRACT
The relationship between tyrosine availability and high potassium (K+) induced dopamine (DA) and norepinephrine (NE) efflux was examined in striatum using in vivo microdialysis. High K+ (80 mM) was included in perfusate for two 30 min periods, 2.5 h apart. After the first high-K+ perfusion, a tyrosine- and phenylalanine-free mixture of large neutral amino acids (LNAA(-)) was administered (IP) to lower brain tyrosine. Tyrosine (0, 25, 50 or 100 mg/kg IP) was administered 30 min prior to the second high-K+ perfusion. The ratio of catecholamine efflux during the two perfusions (P2/P1) was compared between groups. LNAA(-) significantly lowered P2/P1 for both DA and NE. Tyrosine 25-50 mg/kg blocked the LNAA(-) effect. We conclude that catecholamine efflux during prolonged depolarization is tyrosine dependent. Analyses of LNAA levels suggest that availability of tyrosine for tyrosine hydroxylation may be modulated by competition between LNAAs within brain extracellular fluid.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Potassium
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Tyrosine
/
Catecholamines
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Presynaptic Terminals
/
Synaptic Transmission
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Corpus Striatum
Limits:
Animals
Language:
En
Journal:
Brain Res
Year:
2008
Type:
Article
Affiliation country:
United States