Selective increase of tumour necrosis factor‐alpha in injured and spared myelinated primary afferents after chronic constrictive injury of rat sciatic nerve

• DOI: 10.1046/j.1460-9568.2003.02504.x
• Publication Date: 2003-03-06T14:51:01Z
• Authors: Maria Schäfers; Christian Geis; Camilla I. Svensson; Z. David Luo; Claudia Sommer
• Keywords: Neurofilament; Dorsal root ganglion; Sensory neuron; Axotomy; Nerve Injury

Abstract Chronic constriction of the sciatic nerve, leading to a hyperalgesic state, results in partial lesion wherein some axons are injured and others remain intact. Here we sought characterize reactive changes which occur DRG cell bodies uninjured projecting skin muscle. Using immunohistochemistry combined with flurorogold fluororuby retrograde labelling define associated axons, analysed immunoreactivity (IR) for tumour necrosis factor‐alpha (TNF), interleukin‐10 (IL‐10), sensory neuron‐specific channel vanilloid receptor 1 (VR1), isolectin B4 (IB4) calcitonin‐gene‐related peptide (CGRP) 4 days after unilateral chronic injury (CCI) rat nerve. TNF IR was predominantly localized neuronal cells. In an intact present 45%, IL‐10 46%, VR1 44%, IB4 51% CGRP 40% all profiles. Four CCI, increased medium‐sized neurons, whereas IL‐10, IB4, small reduced. Importantly, not only but also adjacent spared neurons contributed markedly IR. Neurons both muscle displayed upregulated CCI. colocalized neurofilament trkB, trkA or RET, suggesting selective phenotypic switch presumably low‐threshold myelinated primary afferents. Spared fibres functions expression may contribute behavioural observed nerve injury.