BILATERAL SEIZURE-RELATED CHANGES OF EXTRACELLULAR GLUTAMATE CONCENTRATION IN HIPPOCAMPI DURING DEVELOPMENT OF AMYGDALOID KINDLING

To monitor the seizure-related changes of extracellular hippocampal gl utamate (Glu) concentration during the development of amygdaloid kindl ing, we used brain dialysates and an enzymatic cycling technique for G lu determination with a highly sensitive assay and high time resolutio n (1 min). The extracellular Glu level was transiently (for 3 min) enh anced after stimulus and returned rapidly to baseline. In partially ki ndled rats (stage 3), the extracellular Glu level during the first min ute post stimulus was 2.5-3.5-fold that of baseline, while fully kindl ed rats exhibited about a 5-fold increase in Glu level. Amygdaloid kin dling is accompanied by a progressive, transient, stimulus-induced enh ancement of extracellular Glu levels during the first minute post stim ulus in both hippocampi.