Use of In Vivo Single-fiber Recording and Intact Dorsal Root Ganglion with Attached Sciatic Nerve to Examine the Mechanism of Conduction Failure

10.3791/59234 ◽  
2019 ◽  
Author(s):  
Honghui Mao ◽  
Xiuchao Wang ◽  
Wen Chen ◽  
FengYu Liu ◽  
You Wan ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Single Fiber ◽  
Conduction Failure

scholarly journals Cdk5 Phosphorylation of STAT3 in Dorsal Root Ganglion Neurons Is Involved in Promoting Axonal Regeneration After Peripheral Nerve Injury

2020 ◽  
Vol 24 (Suppl 1) ◽  
pp. S19-27
Author(s):  
Jinyeon Hwang ◽  
Uk Namgung
Keyword(s):  
Sciatic Nerve ◽  
Dorsal Root Ganglion ◽  
Peripheral Nerve ◽  
Nerve Injury ◽  
Axonal Regeneration ◽  
Dorsal Root ◽  
Immunofluorescence Staining ◽  
Drg Neurons ◽  
Ganglion Neurons

Purpose: The goal of this study is to investigate the role of cyclin-dependent kinase 5 (Cdk5) in axonal regeneration in dorsal root ganglion (DRG) neurons after peripheral nerve injury.Methods: Crush injury was given on the sciatic nerve in rats. The DRG tissues were prepared 1, 3, and 7 days after injury and used for western blotting and immunofluorescence staining experiments. Primary DRG neurons were prepared and treated with Cdk5 inhibitor roscovitine or used for transfections with plasmid constructs. After immunofluorescence staining, neurite length of DRG neurons was analyzed and compared among experimental groups. In addition, roscovitine was injected into the DRG <i>in vivo</i>, and the sciatic nerve after injury was prepared and used for immunofluorescence staining to analyze axonal regeneration in nerve sections.Results: Levels of Cdk5 and p25 were increased in DRG neurons after sciatic nerve injury (SNI). Levels of S727-p-STAT3, but not Y705-p-STAT3, were increased in the DRG. Immunofluorescence staining revealed that Cdk5 and STAT3 proteins were mostly colocalized in DRG neurons and Y705-p-STAT3 signals were localized within the nucleus area of DRG neurons. A blockade of Cdk5 activity by roscovitine or by transfection with dominant negative Cdk5 (dn-Cdk5) and nonphosphorylatable forms of STAT3 (S727A or Y705F) resulted in significant reductions of the neurite outgrowth of cultured DRG neurons. <i>In vivo</i> administration of roscovitine into the DRG markedly attenuated distal elongation of regenerating axons in the sciatic nerve after injury.Conclusions: Our study demonstrated that Cdk5 activity induced from DRG neurons after SNI increased phosphorylation of STAT3. The activation of Cdk5-STAT3 pathway may be involved in promoting axonal regeneration in the peripheral nerve after injury.

Somatostatin Type 2 Receptor Antibody Enhances Mechanical Hyperalgesia in the Dorsal Root Ganglion Neurons after Sciatic Nerve-pinch Injury: Evidence of Behavioral Studies and Bax Protein Expression

2020 ◽  
Vol 18 (10) ◽  
pp. 791-797
Author(s):  
Qiong Xiang ◽  
Jing-Jing Li ◽  
Chun-Yan Li ◽  
Rong-Bo Tian ◽  
Xian-Hui Li
Keyword(s):  
Sciatic Nerve ◽  
Dorsal Root Ganglion ◽  
Nerve Injury ◽  
Dorsal Root ◽  
Underlying Mechanism ◽  
Dorsal Root Ganglion Neurons ◽  
Mechanical Hyperalgesia ◽  
Bax Protein ◽  
Ganglion Neurons

Background: Our previous study has indicated that somatostatin potently inhibits neuropathic pain through the activation of its type 2 receptor (SSTR2) in mouse dorsal root ganglion and spinal cord. However, the underlying mechanism of this activation has not been elucidated clearly Objective: The aim of this study is to perform the pharmacological studies on the basis of sciatic nerve-pinch mice model and explore the underlying mechanism involving SSTR2. Methods: On the basis of a sciatic nerve-pinch injury model, we aimed at comparing the painful behavior and dorsal root ganglion neurons neurochemical changes after the SSTR2 antibody (anti- SSTR2;5μl,1μg/ml) administration in the mouse. Results: After pinch nerve injury, we found that the mechanical hyperalgesia and severely painful behavior (autotomy) were detected after the application of SSTR2 antibody (anti-SSTR2; 5μl, 1μg/ml) on the pinch-injured nerve. The up-regulated phosphorylated ERK (p-ERK) expression and the apoptotic marker (i.e., Bax) were significantly decreased in DRGs after anti-SSTR2 treatment. Conclusion: The current data suggested that inhibitory changes in proteins from the apoptotic pathway in anti-SSTR2-treated groups might be taking place to overcome the protein deficits caused by SSTR2 antibody and supported the new therapeutic intervention with SSTR2 antagonist for neuronal degeneration following nerve injury.

scholarly journals Temporal mechanically-induced signaling events in bone and dorsal root ganglion neurons after in vivo bone loading

PLoS ONE ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. e0192760
Author(s):  
Jason A. Bleedorn ◽  
Troy A. Hornberger ◽  
Craig A. Goodman ◽  
Zhengling Hao ◽  
Susannah J. Sample ◽  
...  
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Dorsal Root Ganglion Neurons ◽  
Signaling Events ◽  
Bone Loading ◽  
Ganglion Neurons

Axotomy- and Autotomy-Induced Changes in the Excitability of Rat Dorsal Root Ganglion Neurons

2001 ◽  
Vol 85 (2) ◽  
pp. 630-643 ◽  
Author(s):  
Fuad A. Abdulla ◽  
Peter A. Smith
Keyword(s):  
Sciatic Nerve ◽  
Dorsal Root Ganglion ◽  
Spontaneous Activity ◽  
Dorsal Root ◽  
Sensory Nerves ◽  
Dorsal Root Ganglion Neurons ◽  
Small Cells ◽  
Resting Membrane Potential ◽  
Ganglion Neurons ◽  
Induced Changes

The spontaneous, ectopic activity in sensory nerves that is induced by peripheral nerve injury is thought to contribute to the generation of “neuropathic” pain in humans. To examine the cellular mechanisms that underlie this activity, neurons in rat L4–L5 dorsal root ganglion (DRG) were first grouped as “large,” “medium,” or “small” on the basis of their size (input capacitance) and action potential (AP) shape. A fourth group of cells that exhibited a pronounced afterdepolarization (ADP) were defined as AD-cells. Whole cell recording was used to compare the properties of control neurons with those dissociated from rats in which the sciatic nerve had been sectioned (“axotomy” group) and with neurons from rats that exhibited self-mutilatory behavior in response to sciatic nerve section (“autotomy” group). Increases in excitability in all types of DRG neuron were seen within 2–7 wk of axotomy. Resting membrane potential (RMP) and the amplitude and duration of the afterhyperpolarization (AHP) that followed the AP were unaffected. Effects of axotomy were greatest in the small, putative nociceptive cells and least in the large cells. Moderate changes were seen in the medium and AD-cells. Compared to control neurons, axotomized neurons exhibited a higher frequency of evoked AP discharge in response to 500-ms depolarizing current injections; i.e., “gain” was increased and accommodation was decreased. The minimum current required to discharge an AP (rheobase) was reduced. There were significant increases in spike width in small cells and significant increases in spike height in small, medium, and AD-cells. The electrophysiological changes promoted by axotomy were intensified in animals that exhibited autotomy; spike height, and spike width were significantly greater than control for all cell types. Under our experimental conditions, spontaneous activity was never encountered in neurons dissociated from animals that exhibited autotomy. Thus changes in the electrical properties of cell bodies alone may not entirely account for injury-induced spontaneous activity in sensory nerves. The onset of autotomy coincided with alterations in the excitability of large, putative nonnociceptive, neurons. Thus large cells from the autotomy group were muchmore excitable than those from the axotomy group, whereas small cells from the autotomy group were only slightly more excitable. This is consistent with the hypothesis that the onset of autotomy is associated with changes in the properties of myelinated fibers. Changes in Ca2+ and K+ channel conductances that contribute to axotomy- and autotomy-induced changes in excitability are addressed in the accompanying paper.

Rescue of α-SNS Sodium Channel Expression in Small Dorsal Root Ganglion Neurons After Axotomy by Nerve Growth Factor In Vivo

1998 ◽  
Vol 79 (5) ◽  
pp. 2668-2676 ◽  
Author(s):  
S. D. Dib-Hajj ◽  
J. A. Black ◽  
T. R. Cummins ◽  
A. M. Kenney ◽  
J. D. Kocsis ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Dorsal Root Ganglion ◽  
Sodium Channel ◽  
Dorsal Root ◽  
Sodium Current ◽  
Mrna Levels ◽  
Drg Neurons ◽  
Nerve Growth

Dib-Hajj, S. D., J. A. Black, T. R. Cummins, A. M. Kenney, J. D. Kocsis, and S. G. Waxman. Rescue of α-SNS sodium channel expression in small dorsal root ganglion neurons after axotomy by nerve growth factor in vivo. J. Neurophysiol. 79: 2668–2676, 1998. Small (18–25 μm diam) dorsal root ganglion (DRG) neurons are known to express high levels of tetrodotoxin-resistant (TTX-R) sodium current and the mRNA for the α-SNS sodium channel, which encodes a TTX-R channel when expressed in oocytes. These neurons also preferentially express the high affinity receptor for nerve growth factor (NGF), TrkA. Levels of TTX-R sodium current and of α-SNS mRNA are reduced in these cells after axotomy. To determine whether NGF participates in the regulation of TTX-R current and α-SNS mRNA in small DRG neurons in vivo, we axotomized small lumbar DRG neurons by sciatic nerve transection and administered NGF or Ringer solution to the proximal nerve stump using osmotic pumps. Ten to 12 days after pump implant, whole cell patch-clamp recording demonstrated that TTX-R current density was decreased in Ringer-treated axotomized neurons (154 ± 45 pA/pF; mean ± SE) compared with nonaxotomized control neurons (865 ± 123 pA/pF) and was restored partially toward control levels in NGF-treated axotomized neurons (465 ± 78 pA/pF). The V 1/2 for steady-state activation and inactivation of TTX-R currents were similar in control, Ringer- and NGF-treated axotomized neurons. Reverse transcription polymerase chain reaction revealed an upregulation of α-SNS mRNA levels in NGF-treated compared with Ringer-treated axotomized DRG. In situ hybridization showed that α-SNS mRNA levels were decreased significantly in small Ringer-treated axotomized DRG neurons in vivo and also in small DRG neurons that were dissociated and maintained in vitro, so as to correspond to the patch-clamp conditions. NGF-treated axotomized neurons had a significant increase in α-SNS mRNA expression, compared with Ringer-treated axotomized cells. These results show that the administration of exogenous NGF in vivo, to the proximal nerve stump of the transected sciatic nerve, results in an upregulation of TTX-R sodium current and of α-SNS mRNA levels in small DRG neurons. Retrogradely transported NGF thus appears to participate in the control of excitability in these cells via actions that include the regulation of sodium channel gene expression in vivo.

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