Brain amino acid concentration changes during status epilepticus induced by lithium and pilocarpine

Amino acid concentrations were measured in specific structures from the brains of rats decapitated before and during the course of status epilepticus induced by lithium and pilocarpine, with the stages of status defined by the electroencephalographic (EEG) pattern displayed. Early status was marked by discrete seizures on EEG, mid status by continuous spiking, and late status by periodic epileptiform discharges. Aspartate levels were lower than control levels in most regions prior to the onset of status. The decline continued and reached statistical significance in different regions at times from early to late status. Glutamate concentrations were typically higher than control just prior to status onset and then decreased in a manner similar to aspartate, but with less percentage change. gamma-Aminobutyric acid increased during status, with the earliest statistically significant differences observed in mid status. These changes were observed in most forebrain structures studied, but the largest percentage changes in excitatory amino acid concentration were found in substantia nigra, where they fell to less than half of control.