KAINIC ACID-INDUCED GENERALIZED SEIZURES ALTER THE REGIONAL HIPPOCAMPAL EXPRESSION OF THE RAT KV4.2 POTASSIUM CHANNEL GENE

Potassium channels play a key role in the regulation of membrane excit ability. We investigated the gene expression response of the Kv4.2 sub type of potassium channel, in the rat hippocampus, to a brief (5 min) episode of kainic acid-induced seizures. Our results demonstrate that Kv4.2 expression is reduced in the granule cell layer of the dentate g yrus at 3 h post-seizure, while no significant changes in expression a re observed in other hippocampal subfields. At 6 h post-challenge, exp ression in both dentate hilar cells and granule cells is reduced, whil e no other significant changes are observed, At 24 h post-challenge, e xpression levels for Kv4.2 in the dentate granule cells have rebounded to levels greater than control, while expression levels are significa ntly reduced in the CA3 and CA4 subfields. No significant changes in K v4.2 expression are observed in kainic acid-administered animals that fail to seize, indicating that the changes in gene expression result f rom seizure activity and not from the direct actions of the administer ed kainic acid. These results demonstrate that brief kainic acid-induc ed epileptiform activity promotes alterations in the expression levels for the Kv4.2 subtype of potassium channel gene. (C) 1997 Elsevier Sc ience Ireland Ltd.