L-Tyrosine

L-Tyrosine is a non-essential amino acid which can inhibit citrate synthase activity in the posterior cortex. IC50 & Target: Citrate synthase^[1] In Vitro: L-Tyrosine inhibits citrate synthase activity in the posterior cortex (2.0 and 4.0 mM), malate dehydrogenase is not altered by L-Tyrosine and succinate dehydrogenase is increased in the posterior cortex (0.1-4.0 mM), hippocampus (1.0-4.0 mM), striatum (4.0 mM) and liver (0.1-4.0 mM). When complex I activity is analyzed, inhibition is observed in hippocampus (4.0 mM). In addition to inhibition in the hippocampus, complex II also is inhibited in the posterior cortex (0.1-4.0 mM) and liver (1.0, 2.0 and 4.0 mM). For complex II–III, activity is not altered by L-Tyrosine, and complex IV activity has decreased in the posterior cortex (1.0-4.0 mM) following treatment with L-Tyrosine^[1]. In Vivo: The acute administration of L-Tyrosine inhibits the activity of citrate synthase in the posterior cortex and liver; however, in the striatum, the activity is increased. The results also demonstrate that acute administration of L-Tyrosine inhibits malate dehydrogenase and complex II, II–III and IV of the mitochondrial respiratory chain activity in the posterior cortex and liver of rats. The succinate dehydrogenase enzyme and complex I activity are inhibited in the posterior cortex and increased in the striatum. Furthermore, energy metabolism in the hippocampus is not amended by an acute administration of L-Tyrosine^[1].