The effect of increased brain
GABA levels on fully kindled amygdala
seizures was investigated in Long-Evans rats. The newly synthesized
GABA-transaminase inhibitor,
gamma-acetylenic GABA (GAG) administered on four consecutive days (100 mg/kg, followed by 50 mg/kg, i.p.) was found to either significantly reduce, or eliminate entirely, the behavioral
seizures normally produced by amygdala stimulation. The effect is seen after the first injection of GAG although its magnitude was greater on subsequent days. Behavioral
seizures reappeared 2 to 3 days after termination of GAG treatment. The duration of electrographic
seizures (self-sustained amygdala after discharge) was either unchanged or greater on the first day of GAG treatment, but was briefer on subsequent days. The duration of afterdischarges returned to normal levels 1 to 2 days earlier than the behavioral
seizures after the termination of GAG.
Picrotoxin (1.5-2 mg/kg, i.p.) did not antagonize either electrographic or behavioral effects of inhibition produced with GAG. Electrical stimulation of amygdala delivered during the initial sedation stage induced by
picrotoxin resulted in further regression of kindled
seizures in the majority of animals. Although in doses employed, GAG alleviates amygdaloid-kindled
seizures its use requires caution in view of its ability to reduce arousal level.