1. Tyrosine-free amino acid mixture attenuates amphetamine-induced displacement of [11C]raclopride in striatum in vivo: A rat PET study.
- Author
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Marisa Le Masurier, Gavin Houston, Philip Cowen, Paul Grasby, Trevor Sharp, and Susan Hume
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TYROSINE , *AMINO acids , *MIXTURES , *AMPHETAMINES , *DOPAMINE , *POSITRON emission , *POSITRON emission tomography - Abstract
Previous neurochemical and behavioural studies show that tyrosine depletion using a nutritionally balanced tyrosine-free amino acid mixture attenuates the dopamine-releasing and psychostimulant properties of amphetamine. Here we investigate the effect of a tyrosine-free amino acid mixture on striatal binding of [11C]raclopride, and amphetamine-induced [11C]raclopride displacement, using positron emission tomography in the rat. Rats were scanned for 60 min after an i.v. injection of ~11 MBq [11C]raclopride using a quad-HIDAC system. Amphetamine (2 mg/kg i.p., 30 min prior to scan) caused a 12% reduction in [11C]raclopride distribution volume ratio (DVR) compared to saline-injected controls. The tyrosine-free amino acid mixture (1 g/kg i.p.) caused a small (+7%) but statistically insignificant increase in [11C]raclopride DVR and attenuated, although it did not fully block, the amphetamine-induced reduction. These data are in keeping with previous neurochemical, immunocytochemical, and behavioural studies showing that tyrosine-free amino acid mixtures reduce dopamine function and offer promise for future PET studies testing the effect of tyrosine-depleting paradigms on dopamine release in humans. Synapse 51:151157, 2004. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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