Nav1.1 localizes to axons of parvalbumin-positive inhibitory interneurons: A circuit basis for epileptic seizures in mice carrying an Scn1a gene mutation

Ikuo Ogiwara, Hiroyuki Miyamoto, Noriyuki Morita, Nafiseh Atapour, Emi Mazaki, Ikuyo Inoue, Tamaki Takeuchi, Shigeyoshi Itohara, Yuchio Yanagawa, Kunihiko Obata, Teiichi Furuichi, Takao K. Hensch, Kazuhiro Yamakawa

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492 Citations (Scopus)

Abstract

Loss-of-function mutations in human SCN1A gene encoding Nav1.1 are associated with a severe epileptic disorder known as severe myoclonic epilepsy in infancy. Here, we generated and characterized a knock-in mouse line with a loss-of-function nonsense mutation in the Scn1a gene. Both homozygous and heterozygous knock-in mice developed epileptic seizures within the first postnatal month. Immunohistochemical analyses revealed that, in the developing neocortex, Nav1.1 was clustered predominantly at the axon initial segments of parvalbumin-positive (PV) interneurons. In heterozygous knock-in mice, trains of evoked action potentials in these fast-spiking, inhibitory cells exhibited pronounced spike amplitude decrement late in the burst. Our data indicate that Nav1.1 plays critical roles in the spike output from PV interneurons and, furthermore, that the specifically altered function of these inhibitory circuits may contribute to epileptic seizures in the mice.

Original languageEnglish
Pages (from-to)5903-5914
Number of pages12
JournalJournal of Neuroscience
Volume27
Issue number22
DOIs
Publication statusPublished - 30 May 2007

Keywords

  • Fast spiking
  • Interneurons
  • Na1.1
  • Parvalbumin-positive
  • SCN1A
  • Severe myoclonic epilepsy in infancy

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