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Updated: Jul 3, 2026

Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments
Published on: February 12, 2021
Nav1.1 is predominantly expressed in nodes of Ranvier and axon initial segments
Amandine Duflocq1, Barbara Le Bras, Erika Bullier
1UPMC Univ Paris 06, UMR 7101, Paris, France.
Abstract:
Aggregation of voltage-gated sodium (Nav) channels in the axon initial segment (AIS) and nodes of Ranvier is essential for the generation and propagation of action potentials. From the three Nav channel isoforms (Nav1.1, Nav1.2 and Nav1.6) expressed in the adult CNS, Nav1.1 appears to play an important function since numerous mutations in its coding sequence cause epileptic syndromes. Yet, its distribution is still controversial. Here we demonstrate for the first time that in the adult CNS Nav1.1 is expressed in nodes of Ranvier throughout the mouse spinal cord and in many brain regions. We identified three populations of nodes: expressing Nav1.1, Nav1.6 or both. We also found Nav1.1 expression concentrated in a proximal AIS subcompartment in spinal cord neurons including 80% of motor neurons and in multiple brain areas. This novel distribution suggests that Nav1.1 is involved in the control of action potential generation and propagation.
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