Centrifugal activity in afferent C-fibers influences the spontaneous afferent barrage generated in nerve-end neuromas.

We have investigated the effect of a prolonged, low-frequency impulse barrage on the spontaneous afferent discharge that originates in experimental nerve-end neuromas in the rat sciatic nerve. Centrifugal activity in afferent A-fibers did not affect electrogenesis in the neuroma. When C-fibers were recruited, however, over half of the axons tested were either suppressed or excited. We suggest that these effects resulted from the stimulation-evoked release of neuroactive peptides or related substances from the cut ends of afferent C-fibers.