2013 Volume 16 Issue 2 Pages 67-72
Although it was reported that a long term supplementation of dietary L-tyrosine, an amino acid that is a precursor of catecholamine, alleviated the chronic stress induced behaviors, limited information is available on the comparison between the effects of L- and D-tyrosine during acute stress. In the present study, the short term effects of oral administration of L- and D-tyrosine on behavioral alterations induced by acute stress were investigated along with the analysis of these two forms of amino acid concentrations in the mouse brain. Locomotor activity in the open field was not altered by either L- or D-tyrosine. Plasma L-tyrosine concentration was greatly but D-tyrosine was moderately increased after 35 min of the treatment. Interestingly, D-tyrosine concentrations were 1.8-2.5 folds higher compared with L-tryrosine in the several brain sites, namely prefrontal cortex, hippocampus, striatum, thalamus, hypothalamus, brain stem and cerebellum of control mice. In all the brain sites determined, L-tyrosine treatment increased the concentrations of L-tyrosine, but D-tyrosine treatment did not increase D-tyrosine levels. In conclusion, our results suggest that orally administered L- and D-tyrosine did not modify locomotor activity, but transportation of tyrosine into brain may be different between L- and D-tyrosine in mice.
