The contribution of capsaicin-sensitive afferents to the dorsal root ganglion sprouting of sympathetic axons after peripheral nerve injury in the rat.

Transection of the sciatic nerve leads to sprouting of sympathetic efferent, noradrenergic axons and terminals around large cell bodies in the dorsal root ganglion. Here we examined whether injury to unmyelinated afferents contributes to the sprouting. Neonatal treatment with the C-fiber neurotoxin capsaicin increased sprouting after nerve injury. We conclude that injury to large, rather than small diameter fibers, triggers the sprouting of sympathetic efferents after nerve injury.