Abstracts

Rationale: Seizures and status epilepticus wereinduced when N-methyl D-aspartate (NMDA was co-perfused into ventral hippocampusof rats. Microdialysis was used to measure extracellular glutamate andg-aminobutyric acid (GABA) levels prior to and during seizures to assessbalance between excitation and inhibition. Methods: In vivo microdialysis was combined withon-line enzyme fluorometric detection of glutamate and GABA prior to and duringinfusion of either 10 mM or 1 mM NMDA for 10 minutes. NMDA receptor stimulation baseline was obtained with aCSF. Results: With seizure induction marked elevation in glutamate was followed by a delay in the appearance of GABA(see Figure). Conclusions: Marked increase in glutamate release was associated with NMDA-R stimulation and subsequent seizures. Increased quantities of GABA in microdialysate were delayed; we wondered if continuousseizures were related to a delay in compensatory responses that should suppress seizures.