Tyrosine depletion attenuates the behavioural stimulant effects of amphetamine and cocaine in rats.
Neurochemical studies show that a tyrosine-free amino acid mixture depletes brain tyrosine and decreases dopamine synthesis and release. Here, we tested whether such a mixture would reduce the behavioural effects of amphetamine and other psychostimulants. A tyrosine-free amino acid mixture decreased the behavioural activation induced by both D-amphetamine (2 mg/kg s.c.) and cocaine (2 mg/kg s.c.). In contrast, the activation induced by the dopamine agonist, apomorphine (0.75 and 5 mg/kg s.c.), or the 5-hydroxytryptamine releasing agent, p-chloroamphetamine (2 mg/kg s.c.) was not altered. These findings provide behavioural evidence that tyrosine-free amino acid mixtures reduce presynaptic dopamine function in the brain.
McTavish
S F
SF
University Department of Psychiatry, Warneford Hospital, Oxford, UK.
Raumann
B
B
Cowen
P J
PJ
Sharp
T
T
D000596:Amino Acids / Q000494:pharmacology; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014443:Tyrosine / Q000494:pharmacology*; D010133:p-Chloroamphetamine / Q000494:pharmacology
D000596:Amino Acids; D000697:Central Nervous System Stimulants; D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D014443:Tyrosine; D010133:p-Chloroamphetamine; D000661:Amphetamine; D003042:Cocaine; D001058:Apomorphine