Abstract
Expressions of voltage-gated sodium channels Nav1.1 and Nav1.2, encoded by SCN1A and SCN2A genes, respectively, have been reported to be mutually exclusive in most brain regions. In adult neocortex, Nav1.1 is dominant in inhibitory neurons while Nav1.2 is dominant in excitatory neurons. Although a distinct subpopulation of neocortical excitatory neurons was also reported to express Nav1.1, their nature has been uncharacterized. By using newly-generated transgenic mouse lines expressing Scn1a promoter-driven green fluorescent protein (GFP), here we confirm mutually-exclusive expressions of Nav1.1 and Nav1.2, absence of Nav1.1 in hippocampal excitatory neurons, and further show that among neocortical excitatory neurons Nav1.1 is expressed in pyramidal tract and a subpopulation of cortico-cortical while Nav1.2 in cortico-striatal, cortico-thalamic and a distinct subpopulation of cortico-cortical projection neurons. These observations now contribute to the elucidation of pathological neural circuits for epilepsies and neurodevelopmental disorders caused by SCN1A and SCN2A mutations including sudden death in Dravet syndrome.
Competing Interest Statement
The authors have declared no competing interest.