Sodium channel β1 subunit localizes to axon initial segments of excitatory and inhibitory neurons and shows regional heterogeneity in mouse brain

Abstract

The β1 subunit of voltage-gated sodium channels, Navβ1, plays multiple roles in neurons spanning electrophysiological modulation of sodium channel α subunits to cell adhesion and neurite outgrowth. This study used immunohistochemistry to investigate Navβ1 subneuronal and regional expression. Navβ1 was enriched at axon initial segments (AIS) and nodes of Ranvier. Navβ1 expression at the AIS was detected throughout the brain, predominantly in the hippocampus, cortex, and cerebellum. Despite expression of Navβ1 in both excitatory and inhibitory AIS, it displayed a marked and fine-grained heterogeneity of expression. Such heterogeneity could have important implications for the tuning of single n..