Action of inhibitory amino acids on acute epileptic foci: An electrographic study

Abstract

Epileptiform activity was induced in adult cats anesthetized with Ketamine or Na-pentobarbital. Acute models of focal epilepsy were created by application of various epileptogenic agents to neocortical or limbic structures. Inhibitory amino acids were injected intravenously and their effects on epileptiform discharges monitored for 2 h after administration. Amino acid solutions were adjusted to pH between 5.5 and 8. Glycine (to 250 mg/kg) did not induce any change. Short-lasting inhibitory effects (5 s to 9 min) were noted with β-alanine, γ-aminobutyric acid (GABA) (>80 mg/kg), taurine (>50 mg/kg), and 3-aminopropane sulfonic acid (3-APS, >5 mg/kg). The action of 3-APS was particularly powerful in abolishing cortical spiking with only moderate depression of background EEG activity. GABA, taurine, and 3-APS also induced depression of respiration in animals under barbiturate anesthesia. In addition, 3-APS caused a 20% decrease in systolic blood pressure. Similar and even greater pressure decreases were observed after injection of control drugs which did not, however, affect the epileptic firing rate. 3-APS seems to deserve further investigation as a possible antiepileptic and GABA-mimetic agent.