scholarly journals Melatonin inhibits the up-regulation of N-type calcium channel in neuropathic pain by activating the MT2 receptor in rats

2021 ◽  
Author(s):  
JUN-JIE TIAN ◽  
YING-YING ZHANG ◽  
ZHAO-YANG TAN ◽  
NAN CAO ◽  
ZU-WEI QU ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Calcium Channel ◽  
Dorsal Root ◽  
The Other ◽  
Spared Nerve Injury ◽  
Drg Neurons ◽  
Activation Curve ◽  
Inactivation Curve ◽  
Whole Cell Patch Clamp ◽  
Behavioral Studies

The aim of the study was to clarify the effect of melatonin on neuropathic pain by N-type calcium channel (Cav2.2) inhibition in dorsal root ganglion (DRG) neurons after spared nerve injury (SNI) surgery. Immunofluorescence was used to identify the co-expression of Cav2.2 and the MT2 receptor and detect the changes in Cav2.2 expression in DRG neurons. Western-blot was also performed to detect the expression of Cav2.2 in DRG neurons. The action potential and current of Cav2.2 channels in DRG neurons were detected using whole-cell patch clamp analysis. Behavioral studies were conducted using thermal stimulation and acetone after melatonin was injected intraperitoneally. The results revealed that Cav2.2 and the MT2 receptor were co-expressed in medium and small sized DRG neurons, and the intensity of Cav2.2 increased after SNI. Injection of melatonin activated the MT2 receptor and relieved nociceptive pain through decreased the Cav2.2 expression and current in DRG neurons. Melatonin can significantly decrease the increase in Cav2.2 current density and excitability after SNI. In addition, the Cav2.2 activation curve shifted to the left after SNI, but there was no change in inactivation. 10 μM melatonin significantly inhibited the excitability of DRG neurons and Cav2.2 current, the inactivation curve of Cav2.2 current shifted significantly to the left. However, the MT2 receptor antagonist 4-P-PDOT reversed the inhibition of melatonin on Cav2.2 current. We conclude that melatonin inhibits the increased Cav2.2 expression and current; on the other hand, it reduces the excitability of DRG neurons after SNI surgery via the MT2 receptor pathway.

scholarly journals Abnormal Reinnervation of Denervated Areas Following Nerve Injury Facilitates Neuropathic Pain

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1007 ◽  
Author(s):  
Hodaya Leibovich ◽  
Nahum Buzaglo ◽  
Shlomo Tsuriel ◽  
Liat Peretz ◽  
Yaki Caspi ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Nerve Injury ◽  
Peripheral Nerves ◽  
Dorsal Root ◽  
Pain Sensitivity ◽  
Spared Nerve Injury ◽  
Drg Neurons ◽  
Nociceptive Neurons ◽  
Peripheral Innervation ◽  
Innervation Patterns

An injury to peripheral nerves leads to skin denervation, which often is followed by increased pain sensitivity of the denervated areas and the development of neuropathic pain. Changes in innervation patterns during the reinnervation process of the denervated skin could contribute to the development of neuropathic pain. Here, we examined the changes in the innervation pattern during reinnervation and correlated them with the symptoms of neuropathic pain. Using a multispectral labeling technique—PainBow, which we developed, we characterized dorsal root ganglion (DRG) neurons innervating distinct areas of the rats’ paw. We then used spared nerve injury, causing partial denervation of the paw, and examined the changes in innervation patterns of the denervated areas during the development of allodynia and hyperalgesia. We found that, differently from normal conditions, during the development of neuropathic pain, these areas were mainly innervated by large, non-nociceptive neurons. Moreover, we found that the development of neuropathic pain is correlated with an overall decrease in the number of DRG neurons innervating these areas. Importantly, treatment with ouabain facilitated reinnervation and alleviated neuropathic pain. Our results suggest that local changes in peripheral innervation following denervation contribute to neuropathic pain development. The reversal of these changes decreases neuropathic pain.

scholarly journals An integrated cell isolation and purification method for rat dorsal root ganglion neurons

2019 ◽  
Vol 47 (7) ◽  
pp. 3253-3260
Author(s):  
Huaishuang Shen ◽  
Minfeng Gan ◽  
Huilin Yang ◽  
Jun Zou
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root Ganglion ◽  
Primary Culture ◽  
Dorsal Root ◽  
Cell Isolation ◽  
Dorsal Root Ganglion Neurons ◽  
Drg Neurons ◽  
Purification Method ◽  
Isolation And Purification ◽  
Ganglion Neurons

Objective Neurobiology studies are increasingly focused on the dorsal root ganglion (DRG), which plays an important role in neuropathic pain. Existing DRG neuron primary culture methods have considerable limitations, including challenging cell isolation and poor cell yield, which cause difficulty in signaling pathway studies. The present study aimed to establish an integrated primary culture method for DRG neurons. Methods DRGs were obtained from fetal rats by microdissection, and then dissociated with trypsin. The dissociated neurons were treated with 5-fluorouracil to promote growth of neurons from the isolated cells. Then, reverse transcription polymerase chain reaction and immunofluorescence assays were used to identify and purify DRG neurons. Results Isolated DRGs were successfully dissociated and showed robust growth as individual DRG neurons in neurobasal medium. Both mRNA and protein assays confirmed that DRG neurons expressed neurofilament-200 and neuron-specific enolase. Conclusions Highly purified, stable DRG neurons could be easily harvested and grown for extended periods by using this integrated cell isolation and purification method, which may help to elucidate the mechanisms underlying neuropathic pain.

scholarly journals The fibroblast-derived protein PI16 controls neuropathic pain

2020 ◽  
Vol 117 (10) ◽  
pp. 5463-5471 ◽  
Author(s):  
Pooja Singhmar ◽  
Ronnie The Phong Trinh ◽  
Jiacheng Ma ◽  
XiaoJiao Huo ◽  
Bo Peng ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root ◽  
Clinical Problem ◽  
Endothelial Barrier ◽  
Leukocyte Infiltration ◽  
Spared Nerve Injury ◽  
Protein Levels ◽  
Major Clinical Problem

Chronic pain is a major clinical problem of which the mechanisms are incompletely understood. Here, we describe the concept that PI16, a protein of unknown function mainly produced by fibroblasts, controls neuropathic pain. The spared nerve injury (SNI) model of neuropathic pain increases PI16 protein levels in fibroblasts in dorsal root ganglia (DRG) meninges and in the epi/perineurium of the sciatic nerve. We did not detect PI16 expression in neurons or glia in spinal cord, DRG, and nerve. Mice deficient in PI16 are protected against neuropathic pain. In vitro, PI16 promotes transendothelial leukocyte migration. In vivo, Pi16−/− mice show reduced endothelial barrier permeability, lower leukocyte infiltration and reduced activation of the endothelial barrier regulator MLCK, and reduced phosphorylation of its substrate MLC2 in response to SNI. In summary, our findings support a model in which PI16 promotes neuropathic pain by mediating a cross-talk between fibroblasts and the endothelial barrier leading to barrier opening, cellular influx, and increased pain. Its key role in neuropathic pain and its limited cellular and tissue distribution makes PI16 an attractive target for pain management.

scholarly journals Oxaliplatin Depolarizes the IB4– Dorsal Root Ganglion Neurons to Drive the Development of Neuropathic Pain Through TRPM8 in Mice

2021 ◽  
Vol 14 ◽  
Author(s):  
Bin Wu ◽  
Xiaolin Su ◽  
Wentong Zhang ◽  
Yi-Hong Zhang ◽  
Xinghua Feng ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Trp Channels ◽  
Membrane Depolarization ◽  
Membrane Excitability ◽  
Drg Neurons ◽  
Induced Membrane ◽  
Sensory Hypersensitivity ◽  
Ganglion Neurons

Use of chemotherapy drug oxaliplatin is associated with painful peripheral neuropathy that is exacerbated by cold. Remodeling of ion channels including TRP channels in dorsal root ganglion (DRG) neurons contribute to the sensory hypersensitivity following oxaliplatin treatment in animal models. However, it has not been studied if TRP channels and membrane depolarization of DRG neurons serve as the initial ionic/membrane drives (such as within an hour) that contribute to the development of oxaliplatin-induced neuropathic pain. In the current study, we studied in mice (1) in vitro acute effects of oxaliplatin on the membrane excitability of IB4+ and IB4– subpopulations of DRG neurons using a perforated patch clamping, (2) the preventative effects of a membrane-hyperpolarizing drug retigabine on oxaliplatin-induced sensory hypersensitivity, and (3) the preventative effects of TRP channel antagonists on the oxaliplatin-induced membrane hyperexcitability and sensory hypersensitivity. We found (1) IB4+ and IB4– subpopulations of small DRG neurons displayed previously undiscovered, substantially different membrane excitability, (2) oxaliplatin selectively depolarized IB4– DRG neurons, (3) pretreatment of retigabine largely prevented oxaliplatin-induced sensory hypersensitivity, (4) antagonists of TRPA1 and TRPM8 channels prevented oxaliplatin-induced membrane depolarization, and (5) the antagonist of TRPM8 largely prevented oxaliplatin-induced sensory hypersensitivity. These results suggest that oxaliplatin depolarizes IB4– neurons through TRPM8 channels to drive the development of neuropathic pain and targeting the initial drives of TRPM8 and/or membrane depolarization may prevent oxaliplatin-induce neuropathic pain.

scholarly journals Intrathecal injection of bone marrow stromal cells attenuates neuropathic pain via inhibition of P2X4R in spinal cord microglia

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Yongbo Teng ◽  
Yang Zhang ◽  
Shouwei Yue ◽  
Huanwen Chen ◽  
Yujuan Qu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Bone Marrow ◽  
Neuropathic Pain ◽  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Purinergic Receptor ◽  
Intrathecal Injection ◽  
Transient Receptor Potential Vanilloid ◽  
Drg Neurons ◽  
Analgesic Effects

Abstract Background Neuropathic pain is one of the most debilitating of all chronic pain syndromes. Intrathecal (i.t.) bone marrow stromal cell (BMSC) injections have a favorable safety profile; however, results have been inconsistent, and complete understanding of how BMSCs affect neuropathic pain remains elusive. Methods We evaluated the analgesic effect of BMSCs on neuropathic pain in a chronic compression of the dorsal root ganglion (CCD) model. We analyzed the effect of BMSCs on microglia reactivity and expression of purinergic receptor P2X4 (P2X4R). Furthermore, we assessed the effect of BMSCs on the expression of transient receptor potential vanilloid 4 (TRPV4), a key molecule in the pathogenesis of neuropathic pain, in dorsal root ganglion (DRG) neurons. Results I.t. BMSC transiently but significantly ameliorated neuropathic pain behavior (37.6% reduction for 2 days). We found no evidence of BMSC infiltration into the spinal cord parenchyma or DRGs, and we also demonstrated that intrathecal injection of BMSC-lysates provides similar relief. These findings suggest that the analgesic effects of i.t. BMSC were largely due to the release of BMSC-derived factors into the intrathecal space. Mechanistically, we found that while i.t. BMSCs did not change TRPV4 expression in DRG neurons, there was a significant reduction of P2X4R expression in the spinal cord microglia. BMSC-lysate also reduced P2X4R expression in activated microglia in vitro. Coadministration of additional pharmacological interventions targeting P2X4R confirmed that modulation of P2X4R might be a key mechanism for the analgesic effects of i.t. BMSC. Conclusion Altogether, our results suggest that i.t. BMSC is an effective and safe treatment of neuropathic pain and provides novel evidence that BMSC’s analgesic effects are largely mediated by the release of BMSC-derived factors resulting in microglial P2X4R downregulation.

Effects of dopamine, SKF-38393 and R(-)-NPA on ATP-activated currents in rat DRG neurons

2005 ◽  
Vol 83 (3) ◽  
pp. 267-277 ◽  
Author(s):  
Guo-Hua Li ◽  
Bing-Cai Guan ◽  
Zhi-Wang Li
Keyword(s):  
Dorsal Root Ganglion ◽  
Patch Clamp ◽  
Dorsal Root ◽  
Receptor Agonist ◽  
Skf 38393 ◽  
Drg Neurons ◽  
Whole Cell ◽  
Cell Patch Clamp ◽  
Da Receptors ◽  
Whole Cell Patch Clamp

This study aimed to investigate the effect of the activation of dopamine (DA) receptors on ATP-activated currents (IATP) in freshly isolated dorsal root ganglion (DRG) neurons of rats using whole-cell patch clamp technique in combination with intracellular dialysis. Extracellular application of DA inhibited IATP in half of the neurons tested (39/77, 50.6%), enhanced IATP in a small subset of the neurons (22/77, 28.6%), and had no effect on IATP in the rest (16/77, 20.8%). To investigate the DA receptor subtypes that mediate these modulations, the effects of R(-)-NPA, a D2 receptor agonist, and SKF-38393, a D1 receptor agonist, were examined. Preapplication of R(-)-NPA inhibited IATP in most of the cells tested (53/57, 93.0%) and had no effect in the rest (4/57, 7.0%); no potentiating effect was observed. Preapplication of SKF-38393 inhibited IATP in a majority of the cells tested (57/77, 74.0%), potentiated IATP in some cells (12/77, 15.6%), and had no effect in the remainder (8/77, 10.4%). Further study of the inhibitory effect of R(-)-NPA and SKF-38393 revealed that both of them acted in a noncompetitive manner, shifting the concentration-response curve for IATP downwards with the maximal response markedly reduced and EC50 basically unchanged; and the inhibition was independent of the holding potential. Intracellular dialysis of GDP-β-S and H-7 abolished R(-)-NPA inhibition of IATP completely, and SKF-38393 inhibition of IATP was removed by intracellular application of H-7 but not by H-9. These results suggest that the activation of DA receptors dominantly inhibits IATP in dorsal root ganglion cells, and this inhibition may be involved in the modulation of afferent information by the diencephalon-derived DA in the primary sensory neurons.Key words: dopamine, ATP, R(-)-NPA, SKF-38393, dorsal root ganglion, whole-cell patch clamp recording, intracellular dialysis.

The Roles of T-Type Calcium Channel in the Development of Neuropathic Pain following Chronic Compression of Rat Dorsal Root Ganglia

Pharmacology ◽  
2010 ◽  
Vol 85 (5) ◽  
pp. 295-300 ◽  
Author(s):  
Xian-Jie Wen ◽  
Shi-Yuan Xu ◽  
Zhi-Xin Chen ◽  
Cheng-Xiang Yang ◽  
Hua Liang ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Calcium Channel ◽  
Dorsal Root Ganglia ◽  
Dorsal Root
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