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Fifteen healthy volunteers received d-amphetamine (20 mg orally) 2 h after ingesting either a nutritionally balanced amino acid mixture or one lacking the catecholamine precursors, tyrosine and phenylalanine (TYR-free). Plasma tyrosine levels were significantly lowered in subjects who received the TYR-free mixture but mean plasma amphetamine levels were higher. Despite this, the TYR-free mixture appeared to decrease the subjective psychostimulant effects of amphetamine, as determined by visual analogue scales. In contrast, the TYR-free mixture failed to lower the subjective anorectic effect of amphetamine. These findings are consistent with animal experimental studies indicating that tyrosine depletion attenuates the release of dopamine produced by amphetamine but not the release of noradrenaline.

Original publication

DOI

10.1177/026988119901300205

Type

Journal article

Journal

J Psychopharmacol

Publication Date

1999

Volume

13

Pages

144 - 147

Keywords

Adult, Appetite, Arousal, Dextroamphetamine, Dopamine, Double-Blind Method, Female, Humans, Hunger, Male, Middle Aged, Norepinephrine, Pain Measurement, Phenylalanine, Tyrosine