Relationships between electroencephalographic pattern and biochemical picture of the cobalt epileptogenic lesion after cortical superfusion with taurine

Abstract Cobalt gelatin pellets were implanted into the feline cortex pretreated with a superfusion of taurine. The following results were obtained. (i) The antiepileptic action of taurine was confirmed. Taurine superfusion remarkably delayed the onset and subsequent development of focal epileptic activity. At the end of superfusion, the taurine cortical concentration was highly increased whereas the glutamic acid level was reduced. The appearance and evolution of focal epileptic discharges was paralleled by a progressively more extensive decrease in concentration of several amino acids. A relationship between the taurine and glutamate levels and the depression of epileptic susceptibility of cortex is pointed out. In addition, the more severe alterations of cortical amino acid content in the cobalt focus in comparison with the penicillin focus under the same experimental conditions as used previously (L. Durelli et al. 1976. Exp. Neurol. 52 : 30–39) are outlined. (ii) The taurine-induced prolonged suppression of focal epileptic activity was associated with epileptiform electroencephalographic abnormalities recorded in cortical regions far from the site of cobalt implantation. These extrafocal spikes occurred before the onset of the focal activity and decreased, even disappeared, simultaneously with progressive enhancement of the epileptic discharges in the cobalt area. The hypothesis is put forward that cobalt, though topically implanted, might exert an epileptogenic action diffuse to different regions of the brain. Under normal conditions the inhibition by the epileptogenic focus in the cobalt area would not allow the simultaneous development of other epileptogenic zones. The latter would, however, develop if the first zone had been previously inhibited by the local action of taurine.