Enhanced expression of glutamate-aspartate transporter (GLAST) mRNA in the hippocampus and frontal cortex of rats during kainic acid-induced seizure activity

概要

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In vivo microdialysis measurement of extracellular amino acids during kainate (KA)-induced seizure shows an increase of glutamate. Glutamate transporters may regulate the extracellular glutamate concentration during epileptogenesis. We used Northern blotting to measure sequential changes of the glutamate-aspartate transporter (GLAST) mRNA expression in rat hippocampus and frontal cortex during KA-induced epileptogenesis. Systemic administration of KA to induce acute seizures increased GLAST mRNA expression in both the hippocampus and cortex. Enhancement of GLAST mRNA expression was also observed in a chronic seizure model induced by unilateral microinjection of kainic acid into the amygdaloid body. The level of expression increased just after injection of KA and continued to increase in rats sacrificed 1 day, 7 days and 30 days after injection. Thus we found that GLAST mRNA expression is induced by either a single seizure or by repetitive seizure activity. These results suggest that the failure to maintain glutamate and/or the GLAST protein at a normal level could be one of the causes of the molecular and cellular events responsible for the selective vulnerability of neurons during the process of KA-induced epileptogenesis.
日本脳科学会の論文
1998-03-01