Degeneration of Myelinated Efferent Fibers Induces Spontaneous Activity in Uninjured C-Fiber Afferents

• DOI: 10.1523/jneurosci.22-17-07746.2002
• Publication Date: 2018-04-13T22:27:17Z
• Authors: Gang Wu; Matthias Ringkamp; Beth B. Murinson; Esther M. Pogatzki; Timothy V. Hartke; Himali M. Weerahandi; James N. Campbell; John W. Griffin; Richard A. Meyer
• Keywords: Wallerian degeneration; Degeneration (medical); Nociceptor; Fasciculus; Rhizotomy; Spinal nerve

We demonstrated recently that uninjured C-fiber nociceptors in the L4 spinal nerve develop spontaneous activity after transection of L5 nerve. postulated Wallerian degeneration leads to an alteration properties neighboring, afferents from adjacent nerves. To explore role myelinated versus unmyelinated fibers, we investigated effects ventral rhizotomy rat. This lesion predominantly fibers. Mechanical paw-withdrawal thresholds were assessed with von Frey hairs, and teased-fiber techniques used record single Behavioral electrophysiological data collected a blinded manner. Seven days surgery, marked decrease withdrawal was observed but not sham operation. Single fiber recordings revealed low-frequency 25% 8–10 d compared only 11% Paw-withdrawal inversely correlated incidence high-threshold afferents. In normal animals, electrocutaneous stimulation at C-fiber, A-fiber, strength produced behavioral signs secondary mechanical hyperalgesia on paw. These results suggest efferent fibers is sufficient induce hyperalgesia. Ectopic injured required for development neuropathic pain behavior. provide additional evidence pain.