Expression of the sodium channel beta3 subunit in injured human sensory neurons.
Casula MA., Facer P., Powell AJ., Kinghorn IJ., Plumpton C., Tate SN., Bountra C., Birch R., Anand P.
Voltage-gated sodium channel alpha-subunits play a key role in pain pathophysiology, and are modulated by beta-subunits. We previously reported that beta1- and beta2-subunits were decreased in human sensory neurons after spinal root avulsion injury. We have now detected, by immunohistochemistry, beta3-subunits in 82% of small/medium and 67% of large diameter sensory neurons in intact human dorsal root ganglia: 54% of beta3 small/medium neurons were NGF receptor trkA negative. Unlike beta1- and beta2, beta3-immunoreactivity did not decrease after avulsion injury, and the beta3:neurofilament ratio was significantly increased in proximal injured human nerves. beta3-subunit expression may thus be regulated differently from beta1, beta2 and Nav1.8. Targeting beta3 interactions with key alpha-subunits, particularly Nav1.3 and Nav1.8, may provide novel selective analgesics.