Direct injection into the dorsal root ganglion: Technical, behavioral, and histological observations

Gregory Fischer, Sandra Kostic, Hiroyuki Nakai, Frank Park, Damir Sapunar, Hongwei Yu, Quinn Hogan

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Direct injection of agents into the dorsal root ganglia (DRGs) offers the opportunity to manipulate sensory neuron function at a segmental level to explore pathophysiology of painful conditions. However, there is no described method that has been validated in detail for such injections in adult rats. We have found that 2. μl of dye injected through a pulled glass pipette directly into the distal DRG, exposed by a minimal foraminotomy, produces complete filling of the DRG with limited extension into the spinal roots. Injection into the spinal nerve required 3. μl to achieve comparable DRG filling, produced preferential spread into the ventral root, and was accompanied by substantial leakage of injected solution from the injection site. Injections into the sciatic nerve of volumes up to 10. μl did not reach the DRG. Transient hypersensitivity to mechanical stimulation at threshold (von Frey) and noxious levels (pin) developed after 2. μl saline injection directly into the DRG that was in part attributable to the surgical exposure procedure alone. Only minimal astrocyte activation in the spinal dorsal horn was evident after DRG saline injections. Injection of adeno-associated virus (AAV) vector conveying green fluorescent protein (GFP) transgene resulted in expression as soon as 1 day after injection into the DRG, including fibers in the spinal dorsal horn and columns. AAV injection into the DRG produced additional thermal hypersensitivity and withdrawal from the stroke of a brush and compromised motor performance. These findings demonstrate a method for selective injection of agents into single DRGs for anatomically restricted actions.

Original languageEnglish (US)
Pages (from-to)43-55
Number of pages13
JournalJournal of Neuroscience Methods
Volume199
Issue number1
DOIs
StatePublished - Jul 15 2011

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Keywords

  • Dorsal root ganglion
  • Gene therapy
  • Injection technique
  • Neuropathic pain
  • Pain treatment
  • Regional anesthesia

ASJC Scopus subject areas

  • Neuroscience(all)

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