Meanwhile, disturbances in the metabolism of glutamate, GABA, tryptophan (TRP), serotonin, taurine, dopamine, and norepinephrine, which are synthesized and/or metabolized by PLPdependent enzymes [20–32], have been repeatedly found in epileptic patients. The increased levels of excitatory amino acids—glutamate, aspartate, and glycine [21–27] along with the reduced levels of inhibitory amino acids and amines—GABA, serotonin, and taurine [28–32] were detected in the plasma, cerebrospinal fluid (CSF), and epileptogenic foci of patients with different forms of epilepsy. Moreover, a moderate increase in the activity of glutamic acid dehydrogenase, the glutamate-synthesizing enzyme, which is specifically inhibited by PLP, has been found in epileptic foci [33].