TY - JOUR
T1 - Direct injection into the dorsal root ganglion
T2 - Technical, behavioral, and histological observations
AU - Fischer, Gregory
AU - Kostic, Sandra
AU - Nakai, Hiroyuki
AU - Park, Frank
AU - Sapunar, Damir
AU - Yu, Hongwei
AU - Hogan, Quinn
N1 - Funding Information:
This study was funded in part by the VA Rehabilitation Research and Development grant 3690-03 (to Q Hogan), and NIH grant DK078388 (to H Nakai).
PY - 2011/7/15
Y1 - 2011/7/15
N2 - 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.
AB - 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.
KW - Dorsal root ganglion
KW - Gene therapy
KW - Injection technique
KW - Neuropathic pain
KW - Pain treatment
KW - Regional anesthesia
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U2 - 10.1016/j.jneumeth.2011.04.021
DO - 10.1016/j.jneumeth.2011.04.021
M3 - Article
C2 - 21540055
AN - SCOPUS:79958117790
SN - 0165-0270
VL - 199
SP - 43
EP - 55
JO - Journal of Neuroscience Methods
JF - Journal of Neuroscience Methods
IS - 1
ER -