Comparison of seizure related amino acid release in human epileptic hippocampus versus a chronic, kainate rat model of hippocampal epilepsy

Wilson, Charles L.; Maidment, Nigel T.; Shomer, Marc H.; Behnke, Eric J.; Ackerson, Larry; Fried, Itzhak; Engel, Jerome

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Volume 26, Issue 1 , Pages 245-254, December 1996

Comparison of seizure related amino acid release in human epileptic hippocampus versus a chronic, kainate rat model of hippocampal epilepsy

Charles L. Wilson
- Corresponding author. Tel.: +1 (310) 825 0576; fax: +1 (310) 206 8461.
- Department of Neurology, UCLA School of Medicine, Los Angeles, CA 90024, USA
- Brain Research Institute, UCLA School of Medicine, Los Angeles, CA 90024, USA
Nigel T. Maidment
- Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine, Los Angeles, CA 90024, USA
- Brain Research Institute, UCLA School of Medicine, Los Angeles, CA 90024, USA
Marc H. Shomer
- Department of Neurology, UCLA School of Medicine, Los Angeles, CA 90024, USA
Eric J. Behnke
- Brain Research Institute, UCLA School of Medicine, Los Angeles, CA 90024, USA
Larry Ackerson
- Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine, Los Angeles, CA 90024, USA
Itzhak Fried
- Division of Neurological Surgery, UCLA School of Medicine, Los Angeles, CA 90024, USA
- Brain Research Institute, UCLA School of Medicine, Los Angeles, CA 90024, USA
Jerome Engel Jr.
- Department of Neurology, UCLA School of Medicine, Los Angeles, CA 90024, USA
- Department of Neurobiology, UCLA School of Medicine, Los Angeles, CA 90024, USA
- Brain Research Institute, UCLA School of Medicine, Los Angeles, CA 90024, USA

Received 29 October 1995; accepted 31 October 1995.

Abstract

Recent microdialysis studies of excitatory and inhibitory amino acid release associated with paroxysmal hippocampal activity have found significant increases in the hippocampus of epileptic patients, but minimal or variable increases in animal models. One possible reason for the differences is that the animal models employed in these studies have not adequately reflected the pathophysiology of human epilepsy. The present study sought to verify the amino acid release reported in human epileptic hippocampus and then employs animal studies using a chronic rat model of epilepsy, in which rats exhibit spontaneous seizure activity 3 to 4 months after injection of kainic acid into the hippocampus. In agreement with earlier reports, we found increases in glutamate, aspartate and GABA during seizures in human hippocampus. In addition we found increases in taurine which have not previously been reported. The chronic rat model shows increases in the same amino acids as in the human epileptic hippocampus, both during spontaneous seizures and stimulation evoked after-discharges (ADs). In contrast, minimal increases are elicited by hippocampal stimulation in control (non-kainate injected) animals. These results correlate with the degree of mossy fiber reorganization found in the dentate gyrus of kainate rats or epileptic humans.

Keywords: In vivo microdialysis, Glutamate, GABA, Taurine, After-discharges, EEG

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