Voltage-gated Na+ channels (Nav) are essential for the generation of action potentials and for cell excitability1. Nav channels are activated in response to depolarization and selectively allow the flow of Na+ ions. To date, nine Nav α subunits have been cloned and named Nav1.1-1.9 . Their expression is developmentally regulated and tissue specific.nNav channels are classified into two groups according to their sensitivity to tetrodotoxin (TTX): TTX-sensitive and TTX-resistant channels.nTTX-resistant channels have been suggested to play an important role in nociceptive transmission. Two TTX-resistant Nav channels are expressed in dorsal root ganglion (DRG) neurons, Nav1.8 and Nav1.9. The Nav1.9 channel (also called NAN or SNS2) is preferentially expressed in small-diameter DRG neurons.nRecently, it has been shown that BDNF activated Nav1.9 channels in the hippocampus suggesting that its expression is not restricted to DRG alone
