title: Dietary Tyrosine Protects Striatal Dopamine Receptors from the Adverse Effects of REM Sleep Deprivation.
abstract: L-Tyrosine is a non-essential amino acid that is produced as an intermediary metabolite in the conversion of phenylalanine to 3,4-dihyroxyphenylalanine (DOPA), and is a precursor of the neurotransmitter dopamine. In previous studies, tyrosine pretreatment was shown to protect against the neurochemical and behavioral deficits of acute stress caused by tail shock or cold exposure in rodents. The present study addressed the hypothesis that tyrosine administration may be an effective counter-measure to dopamine-mediated behaviors induced by rapid eye-movement sleep deprivation (RSD). In order to test the hypothesis, Sprague-Dawley rats were divided into 9 treatment groups: RSD-treated rats on normal-protein diet (20% casein: 1% tyrosine, 1% valine); tank control (TC) rats on a normal diet; cage control (CC) rats on normal diet; RSD-treated rats on 4% tyrosine diet; TC rats on 4% tyrosine diet; CC rats on 4% tyrosine diet; RSD-treated rats on 4% valine diet; TC rats on 4% valine diet; CC rats on 4% valine diet. In the RSD group receiving tyrosine, there was no apparent change in Bmax for binding of the dopamine D2 receptor ligand [(3)H]YM-09151-2 in the striata as compared to the respective TC and CC groups; whereas RSD-treated rats maintained on the normal diet and valine supplementation demonstrated expected increases in Bmax for ligand binding. The TC group on the tyrosine diet showed attenuated catalepsy compared to the corresponding CC group, while the RSD group consuming tyrosine showed a catalepsy that was significantly increased, and similar to that of cage control animais on a control diet. These data suggest that the tyrosine-supplemented diet significantly attenuated RSD-induced changes in striatal dopamine D2 receptors, and the effect appeared sufficient to influence RSD-induced behaviors.
authors.affiliation: a Department of Pharmacology , King Saud University College of Medicine , Abha , Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Hamdi
authors.affiliation: b Neurobehavioral Research Institute , Nashville , Tennessee 37211 , USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Brock
authors.affiliation: b Neurobehavioral Research Institute , Nashville , Tennessee 37211 , USA.
authors.forename: S
authors.initials: S
authors.lastname: Payne
authors.affiliation: b Neurobehavioral Research Institute , Nashville , Tennessee 37211 , USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Ross
authors.affiliation: b Neurobehavioral Research Institute , Nashville , Tennessee 37211 , USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Bond
authors.affiliation: c Section of Endocrinology, Department of Medicine , Louisiana State University Medical Center , New Orleans , Louisiana 70112 , USA.
authors.forename: C
authors.initials: C
authors.lastname: Prasad
keywords: Dopamine receptors; REM sleep deprivation; Tyrosine