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.