Sympathetic Sprouting Near Sensory Neurons After Nerve Injury Occurs Preferentially on Spontaneously Active Cells and Is Reduced by Early Nerve Block
- 1 January 2007
- journal article
- research article
- Published by American Physiological Society in Journal of Neurophysiology
- Vol. 97 (1), 492-502
- https://doi.org/10.1152/jn.00899.2006
Abstract
Some chronic pain conditions are maintained or enhanced by sympathetic activity. In animal models of pathological pain, abnormal sprouting of sympathetic fibers around large- and medium-sized sensory neurons is observed in dorsal root ganglia (DRGs). Large- and medium-sized cells are also more likely to be spontaneously active, suggesting that sprouting may be related to neuron activity. We previously showed that sprouting could be reduced by systemic or locally applied lidocaine. In the complete sciatic nerve transection model in rats, spontaneous activity initially originates in the injury site; later, the DRGs become the major source of spontaneous activity. In this study, spontaneous activity reaching the DRG soma was reduced by early nerve blockade (local perfusion of the transected nerve with TTX for the 1st 7 days after injury). This significantly reduced sympathetic sprouting. Conversely, increasing spontaneous activity by local nerve perfusion with K+ channel blockers increased sprouting. The hyperexcitability and spontaneous activity of DRG neurons observed in this model were also significantly reduced by early nerve blockade. These effects of early nerve blockade on sprouting, excitability, and spontaneous activity were all observed 4–5 wk after the end of early nerve blockade, indicating that the early period of spontaneous activity in the injured nerve is critical for establishing the more long-lasting pathologies observed in the DRG. Individual spontaneously active neurons, labeled with fluorescent dye, were five to six times more likely than quiescent cells to be co-localized with sympathetic fibers, suggesting a highly localized correlation of activity and sprouting.Keywords
This publication has 100 references indexed in Scilit:
- Robust increase of cutaneous sensitivity, cytokine production and sympathetic sprouting in rats with localized inflammatory irritation of the spinal gangliaNeuroscience, 2006
- Sympathetic sprouting and changes in nociceptive sensory innervation in the glabrous skin of the rat hind paw following partial peripheral nerve injuryJournal of Comparative Neurology, 2006
- Autonomic fibre sprouting and changes in nociceptive sensory innervation in the rat lower lip skin following chronic constriction injuryEuropean Journal of Neuroscience, 2005
- Sympathetic Fiber Sprouting in Chronically Compressed Dorsal Root Ganglia Without Peripheral AxotomyJournal Of Neuropathic Pain & Symptom Palliation, 2005
- Dendritic calcium transients in the leech giant glial cell in situGlia, 1999
- Spontaneous discharge originates in the dorsal root ganglion at the onset of a painful peripheral neuropathy in the ratNeuroscience Letters, 1992
- Neuronal activity triggers calcium waves in hippocampal astrocyte networksNeuron, 1992
- Sympathetically-maintained Causalgiform Disorders in a Model for Neuropathic Pain: A ReviewJournal of Basic and Clinical Physiology and Pharmacology, 1991
- Properties of primary afferent neurons from muscle which are spontaneously active after a lesion of their peripheral processesExperimental Neurology, 1982
- The postnatal development of large light and small dark neurons in mouse dorsal root ganglia: a statistical analysis of cell numbers and sizeJournal of Neurocytology, 1979