Effect of α‐Amino‐4‐Phosphonobutyrate on the Release of Endogenous Glutamate and Aspartate from Cortical Synaptosomes of Epileptic Rats

Abstract

The effect of the glutamate antagonist-.alpha.-amino-4-phosphonobutyrate (APBA) on the release of endogenous amino acids from sensorimotor cortical synaptosomes of rats with a cortical Co focus and from non-epileptic rats was studied. The release of endogenous glutamate, aspartate and .gamma.-GABA from synaptosomal preparations of Co-induced epileptogenic tissues was increased compared with the release from the contralateral (sensorimotor) region or the sensorimotor cortex of normal animals. The intrasynaptosomal content of these amino acids was reduced in proportion to the amount released. The levels of other amino acids were unaffected or showed much smaller changes. APBA (0.5-1 mM) decreased significantly the spontaneous release of asparate and glutamate from the epileptic foci without affecting GABA or ony other amino acid. APBA produced no effect whatsoever on the release of any amino acid from synaptosomal preparations of nonepileptic focus.