Expression of the sodium channel β3 subunit in injured human sensory neurons

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 Na(v)1.8. Targeting beta3 interactions with key alpha-subunits, particularly Na(v)1.3 and Na(v)1.8, may provide novel selective analgesics.