Two essential amino acids, L-lysine and L-histidine, in five types of experimental seizures.

L-Lysine (250-2,000 mg/kg) and L-histidine (1,000-2,000 mg/kg) significantly raised the electroconvulsive threshold. D-Histidine (1,000 mg/kg) was completely ineffective in this regard. Both amino acids were generally inactive in pentetrazole-, picrotoxin- and aminophylline-induced seizures, though L-histidine (2,500 mg/kg) significantly reduced the number of mice with clonic convulsions in the pentetrazole test. Also, L-lysine (2,500 and 3,000 mg/kg) significantly diminished mortality rate in aminophylline-induced seizures. In addition, L-lysine (2,500-3,000 mg/kg) and L-histidine (2,000-2,500 mg/kg) delayed the onset of aminophylline- and picrotoxin-evoked convulsions. L-Lysine and L-histidine (both up to 1,000 mg/kg) did not affect amygdala-kindled seizures in rats. The results indicate that some of indispensable amino acids may play a role in the inhibitory transmission in the central nervous system. A possibility arises that appropriate diet may be an important supportive factor in the treatment of some epileptic patients, probably suffering from generalized tonic-clonic seizures.