Sprouting sympathetic fibers form synaptic varicosities in the dorsal root ganglion of the rat with neuropathic injury

Kyungsoon Chung, Young Wook Yoon, Jin Mo Chung

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65 Scopus citations


Peripheral nerve injury in a rat model (spinal nerve ligation) of neuropathic pain triggers sprouting of sympathetic fibers in the dorsal root ganglion (DRG). This sympathetic sprouting has been suggested as an important underlying mechanism for pain behaviors. To investigate the possibility of functional interaction between sprouted sympathetic fibers and sensory neurons, the present study examined the fine morphology and structural relationship between sympathetic fibers and the DRG neurons by electron microscopy. Sympathetic postganglionic fibers, as identified by electron microscopic immunostaining for tyrosine hydroxylase (TH), were all unmyelinated fibers and some of them ended as growth cones. In addition, many vesicle-containing axonal enlargements (we will refer these as synaptic varicosities) were found in the interstitial space around DRG neurons, and some were enclosed within the satellite cell capsule which surrounded the DRG soma. The presence of sympathetic synaptic varicosities near or in apposition with either the DRG somata or their processes provides a structural basis for possible interactions between sensory neurons and sympathetic fibers in the DRG of neuropathic rats.

Original languageEnglish (US)
Pages (from-to)275-280
Number of pages6
JournalBrain Research
Issue number2
StatePublished - Mar 21 1997


  • immunohistochemistry
  • mechanical allodynia
  • peripheral nerve injury
  • sensory ganglion
  • sympathetic sprouting
  • tyrosine hydroxylase
  • ultrastructure

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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