Voltage-gated Na+ channels (NaV) are essential for the generation of action potentials and for cell excitability.1 NaV channels are activated in response to depolarization and selectively allow flow of Na+ ions. To date, nine NaV α subunits have been cloned and named NaV1.1-1.9.Expression of the α subunit is developmentally and tissue specific.The NaV channels are classified into two groups according to their sensitivity to tetrodotoxin (TTX): TTX-sensitive and TTX-resistant channelsnTTX-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 was shown that BDNF activates Nav1.9 channels in the hippocampus suggesting that its expression is not restricted to DRG alone
