Brain amino acid levels in audiogenic seizure-susceptible rats following habituation to the auditory stimulus.

Hippocampic and brain stem levels of amino acids were determined in audiogenic seizure-susceptible rats following habituation by repeated exposure to the acoustic stimulus. The biochemical determinations were performed in the brains of 42 habituated animals and 23 not habituated seizure susceptible rats used as controls. It was found that the habituation process is associated with: a) increased levels of aspartate in hippocampus and pons; b) significantly decreased levels of glycine in the hippocampus and pons; c) decreased concentration of glutamate in the pons; d) no significant changes in the GABA concentrations in hippocampus and brain stem. The changes of the excitatory and inhibitory amino acids in the brain of the habituated rats cannot explain the fall in epileptic susceptibility associated with habituation.