scholarly journals Evans Blue Reduces Neuropathic Pain Behavior by Inhibiting Spinal ATP Release

2019 ◽  
Vol 20 (18) ◽  
pp. 4443 ◽  
Author(s):  
Yin ◽  
Hong ◽  
Phạm ◽  
Shin ◽  
Gwon ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Evans Blue ◽  
Spinal Dorsal Horn ◽  
Critical Role ◽  
Atp Release ◽  
Pain Behavior ◽  
Dependent Manner ◽  
Spinal Dorsal

Upon peripheral nerve injury, vesicular ATP is released from damaged primary afferent neurons. This extracellular ATP subsequently activates purinergic receptors of the spinal cord, which play a critical role in neuropathic pain. As an inhibitor of the vesicular nucleotide transporter (VNUT), Evans blue (EB) inhibits the vesicular storage and release of ATP in neurons. Thus, we tested whether EB could attenuate neuropathic pain behavior induced by spinal nerve ligation (SNL) in rats by targeting VNUT. An intrathecal injection of EB efficiently attenuated mechanical allodynia for five days in a dose-dependent manner and enhanced locomotive activity in an SNL rat model. Immunohistochemical analysis showed that EB was found in VNUT immunoreactivity on neurons in the dorsal root ganglion and the spinal dorsal horn. The level of ATP in cerebrospinal fluid in rats with SNL-induced neuropathic pain decreased upon administration of EB. Interestingly, EB blocked ATP release from neurons, but not glial cells in vitro. Eventually, the loss of ATP decreased microglial activity in the ipsilateral dorsal horn of the spinal cord, followed by a reduction in reactive oxygen species and proinflammatory mediators, such as interleukin (IL)-1β and IL-6. Finally, a similar analgesic effect of EB was demonstrated in rats with monoiodoacetate-induced osteoarthritis (OA) pain. Taken together, these data demonstrate that EB prevents ATP release in the spinal dorsal horn and reduces the ATP/purinergic receptor-induced activation of spinal microglia followed by a decline in algogenic substances, thereby relieving neuropathic pain in rats with SNL.

scholarly journals A systematic review on descending serotonergic projections and modulation of spinal nociception in chronic neuropathic pain and after spinal cord stimulation

2021 ◽  
Vol 17 ◽  
pp. 174480692110439
Author(s):  
Lonne Heijmans ◽  
Martijn R Mons ◽  
Elbert A Joosten
Keyword(s):  
Systematic Review ◽  
Spinal Cord ◽  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Serotonergic System ◽  
Chronic Neuropathic Pain ◽  
Spinal Dorsal ◽  
Important Target ◽  
Serotonergic Modulation

Chronic neuropathic pain is a debilitating ordeal for patients worldwide and pharmacological treatment efficacy is still limited. As many pharmacological interventions for neuropathic pain often fail, insights into the underlying mechanism and role of identified receptors is of utmost importance. An important target for improving treatment of neuropathic pain is the descending serotonergic system as these projections modulate nociceptive signaling in the dorsal horn. Also with use of last resort treatments like spinal cord stimulation (SCS), the descending serotonergic projections are known to be involved in the pain relieving effect. This systematic review summarizes the involvement of the serotonergic system on nociceptive modulation in the healthy adult rodent and the chronic neuropathic rodent and summarizes all available literature on the serotonergic system in the SCS-treated neuropathic rodent. Medline, Embase and Pubmed databases were used in the search for articles. Descending serotonergic modulation of nociceptive signaling in spinal dorsal horn in normal adult rat is mainly inhibitory and mediated by 5-HT1a, 5-HT1b, 5-HT2c, 5-HT3 and 5-HT4 receptors. Upon injury and in the neuropathic rat, this descending serotonergic modulation becomes facilitatory via activation of the 5-HT2a, 5-HT2b and 5-HT3 receptors. Analgesia due to neuromodulatory intervention like SCS restores the inhibitory function of the descending serotonergic system and involves 5-HT2, 5-HT3 and 5-HT4 receptors. The results of this systematic review provide insights and suggestions for further pharmacological and or neuromodulatory treatment of neuropathic pain based on targeting selected serotonergic receptors related to descending modulation of nociceptive signaling in spinal dorsal horn. With the novel developed SCS paradigms, the descending serotonergic system will be an important target for mechanism-based stimulation induced analgesia.

scholarly journals https://painphysicianjournal.com/current/pdf?article=MTgwMw%3D%3D&journal=71

2012 ◽  
Vol 6;15 (6;12) ◽  
pp. E995-E1006
Author(s):  
Prof. Yun-Qing Li
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Inflammatory Cytokines ◽  
Glial Cells ◽  
Mechanical Allodynia ◽  
Spinal Dorsal Horn ◽  
Pain Behavior ◽  
Repeated Treatment ◽  
Single Bolus ◽  
Spinal Dorsal

Background: Current treatments for neuropathic pain are far from satisfactory. Considering the essential contribution of central immune factors to the pathogenesis of neuropathic pain, targeting inflammatory response is well accepted as an effective strategy for treating neuropathic pain. Triptolide has a long history in traditional Chinese medicine for treating inflammatory diseases and has been proven to inhibit cytokines released from glial cells. Objective: In the present study, we tested whether systemic treatment with triptolide could prevent or attenuate nocifensive behaviors associated with neuropathic pain. We further tried to explore the underlying mechanism of the potential anti-allodynia effect of triptolide. Study Design: A randomized, double blind, controlled animal trial. Methods: Triptolide was administered systemically in a rat model of neuropathic pain induced by spinal nerve ligation (SNL) in the single bolus and repeated treatment manners. In the single bolus treatment experiment, triptolide (30 μg/kg, 100 μg/kg, 300 μg/kg) or vehicle was given to SNL and sham-operated rats once on day 1 or on day 10 after surgery (n = 6 each). In the repeated treatment study, prophylactic treatment with triptolide (30 μg/kg, 100 μg/kg, 300 μg/kg) was given to rats during the period of day -3 (3 days prior to SNL) to day 7 (7 days post-SNL) inclusively (n = 6 each). Another set of SNL and sham rats on postoperative day 10 received treatment with triptolide (30 μg/kg, 100 μg/kg, 300 μg/kg) or vehicle during the period of days 11–20 inclusively (n = 6 each), to assess potential reversal of established pain behavior. Mechanical allodynia of the rats was tested with von Frey filaments. Astrocytic and microglial activation in the spinal dorsal horn was evaluated with immunofluorescent histochemistry. Phosphorylation of mitogen-activated protein kinases (MAPKs), and expression of inflammatory cytokines (interleukin-6, interleukin-1beta, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) were examined with Western blot analysis and real-time reverse transcription polymerase chain reaction study. Results: A single bolus treatment with triptolide could neither prevent the induction nor reverse the maintenance of SNL-induced mechanical allodynia. However, repeated administration of triptolide dose-dependently inhibited neuropathic pain behavior in both preventative and interventional paradigms. Triptolide hampered SNL-induced activation of glial cells (astrocytes and microglia) in the spinal dorsal horn without influencing neurons. In addition, SNL-induced phosphorylation of MAPKs could be inhibited by triptolide. Furthermore, up-regulated expression of inflammatory cytokines in neuropathic pain states could be remarkably blocked by triptolide. Limitations: The direct target site (such as a specific receptor) of triptolide is still to be determined. In addition, triptolide could not completely block the SNL-induced mechanical allodynia. Conclusions: Our data suggest that triptolide may be a potential novel treatment for neuropathic pain through modulating immune response in the spinal dorsal horn. Key words: Triptolide, neuropathic pain, spinal dorsal horn, astrocyte, microglia, MAPK.

scholarly journals Sanguinarine Attenuates Neuropathic Pain in a Rat Model of Chronic Constriction Injury

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ping Li ◽  
Yan-Xiu Wang ◽  
Guang Yang ◽  
Zun-Cheng Zheng ◽  
Chao Yu
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
P38 Mapk ◽  
Spinal Dorsal Horn ◽  
Chronic Constriction Injury ◽  
Mapk Signaling ◽  
Dependent Manner ◽  
Withdrawal Threshold ◽  
Spinal Dorsal ◽  
Plant Medicine

Objective. There is still no effective treatment of neuropathic pain. Sanguinarine is a natural plant medicine with anti-inflammatory effects, but its effect on neuropathic pain remains unclear. This study was aimed at investigating the potential of sanguinarine to attenuate neuropathic pain. Methods. Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve. Rats were randomly divided into several groups: sham, CCI, CCI+SG (1.00 mg/kg), CCI+SG (2.50 mg/kg), and CCI+SG (6.25 mg/kg). SG was injected intraperitoneally from the day of surgery every three days. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded before surgery and on days 1, 3, 7, and 14 after surgery. The microglia in the spinal dorsal horn were examined by immunofluorescence. p38 MAPK expression in the spinal dorsal horn was detected by PCR and Western blot analysis. Cytokine levels in the spinal dorsal horn were measured by ELISA. Results. MWT and TWL were significantly reduced in the CCI group, but sanguinarine recovered MWT and TWL in the CCI group. In addition, sanguinarine inhibited the activation of microglia and decreased the expression of p-p38 and TNF-α, IL-1β, and IL-6 in the spinal dorsal horn of the CCI group in a dose-dependent manner. Conclusions. Our results suggest that sanguinarine can attenuate neuropathic pain via inhibiting the activation of microglia and the activation of the p38 MAPK signaling pathway.

scholarly journals Downregulation of Metallothionein-2 Contributes to Oxaliplatin-induced Neuropathic Pain

2020 ◽  
Author(s):  
Xuelin Huang ◽  
Jie Deng ◽  
Ting Xu ◽  
Wenjun Xin ◽  
Yuehong Zhang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Genetic Alterations ◽  
Mrna Levels ◽  
Spinal Cord Neurons ◽  
Spinal Dorsal ◽  
Dorsal Horns ◽  
Prevention And Treatment

Abstract Background We previously reported a correlation between small doses of oxaliplatin penetrating onto the spinal cord and acute pain after chemotherapy. Here we propose that MT2 within the spinal dorsal horns participates the development of oxaliplatin-induced neuropathic pain and may be a pharmacological target for the prevention and treatment of chemotherapy-induced peripheral neuropathy (CIPN). Methods The rat model of CIPN was established by a 5 consecutive injection of oxaliplatin (0.4 mg/ 100 g/ day). Genetic restoration or inhibition of neuron-specific metallothionein-2 was implemented 21 days before oxaliplatin treatment. Mechanical allodynia and locomotor activity were assayed. Cell-specific expression of metallothionein-2, the mRNA levels of pro-inflammatory cytokines, nuclear translocation of NF-κB, the protein levels of expression of IκB-α, and interaction between IκB-α and P65 were evaluated in the spinal dorsal horns. Also, in vitro interaction of sequentially deleted IκB-α promoter with metallothionein-2 was used to assess the signal transduction mechanism. Results We found that oxaliplatin induced downregulation of metallothionein-2 in rat spinal cord neurons. By contrast, genetic restoration of metallothionein-2 in the spinal dorsal horn neuron blocked and reversed neuropathic pain in oxaliplatin-treated rats of both sexes, whereas genetic inhibition of metallothionein-2 triggered neuropathic pain in normal rats. No locomotor impairment was observed after the genetic alterations of metallothionein-2. At the molecular level, metallothionein-2 modulated oxaliplatin-induced neuroinflammation, activation of NF-κB, and transcriptional expression of IκB-α promoter, and these processes could be blocked by genetic restoration of metallothionein-2 in the spinal dorsal horn neurons. Conclusions Metallothionein-2 is a potential target for the prevention and treatment of CIPN. A reduction of NF-κB activation and inflammatory responses by enhancing the transcription of IκB-α promoter is proposed in the mechanism.

scholarly journals Downregulation of metallothionein-2 contributes to oxaliplatin-induced neuropathic pain

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Xuelin Huang ◽  
Jie Deng ◽  
Ting Xu ◽  
Wenjun Xin ◽  
Yuehong Zhang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Locomotor Activity ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Genetic Alterations ◽  
Mrna Levels ◽  
Spinal Dorsal ◽  
Dorsal Horns ◽  
Prevention And Treatment

Abstract Background We previously reported a correlation between small doses of oxaliplatin penetrating onto the spinal cord and acute pain after chemotherapy. Here, we propose that MT2 within the spinal dorsal horns participates in the development of oxaliplatin-induced neuropathic pain and may be a pharmacological target for the prevention and treatment of chemotherapy-induced peripheral neuropathy (CIPN). Methods The rat model of CIPN was established by 5 consecutive injections of oxaliplatin (0.4 mg/100 g/day). Genetic restoration of neuron-specific metallothionein-2 was implemented 21 days before oxaliplatin treatment, and also, genetic inhibition by metallothionein-2 siRNA was performed. Mechanical allodynia and locomotor activity were assayed. Cell-specific expression of metallothionein-2, the mRNA levels of pro-inflammatory cytokines, nuclear translocation of NF-κB, the protein levels of expression of IκB-α, and interaction between IκB-α and P65 were evaluated in the spinal dorsal horns. Also, in vitro interaction of sequentially deleted IκB-α promoter with metallothionein-2 was used to assess the signal transduction mechanism. Results We found that oxaliplatin induced downregulation of metallothionein-2 in rat spinal cord neurons. By contrast, genetic restoration of metallothionein-2 in the spinal dorsal horn neuron blocked and reversed neuropathic pain in oxaliplatin-treated rats of both sexes, whereas genetic inhibition of metallothionein-2 triggered neuropathic pain in normal rats. Overall locomotor activity was not impaired after the genetic alterations of metallothionein-2. At the molecular level, metallothionein-2 modulated oxaliplatin-induced neuroinflammation, activation of NF-κB, and inactive transcriptional expression of IκB-α promoter, and these processes could be blocked by genetic restoration of metallothionein-2 in the spinal dorsal horn neurons. Conclusions Metallothionein-2 is a potential target for the prevention and treatment of CIPN. A reduction of NF-κB activation and inflammatory responses by enhancing the transcription of IκB-α promoter is proposed in the mechanism.

scholarly journals Calcitonin gene-related peptide regulates spinal microglial activation through the histone H3 lysine 27 trimethylation via enhancer of zeste homolog-2 in rats with neuropathic pain

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Qi An ◽  
Chenyan Sun ◽  
Ruidi Li ◽  
Shuhui Chen ◽  
Xinpei Gu ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Spinal Dorsal Horn ◽  
Microglial Activation ◽  
Microglial Cells ◽  
Gene Promoters ◽  
Spinal Dorsal ◽  
Related Peptide ◽  
Calcitonin Gene

Abstract Background Calcitonin gene-related peptide (CGRP) as a mediator of microglial activation at the transcriptional level may facilitate nociceptive signaling. Trimethylation of H3 lysine 27 (H3K27me3) by enhancer of zeste homolog 2 (EZH2) is an epigenetic mark that regulates inflammatory-related gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K27me3 in microglial activation after nerve injury, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain. Methods Microglial cells (BV2) were treated with CGRP and differentially enrichments of H3K27me3 on gene promoters were examined using ChIP-seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on microglial activation and EZH2/H3K27me3 signaling in CCI-induced neuropathic pain. Results Overexpressions of EZH2 and H3K27me3 were confirmed in spinal microglia of CCI rats by immunofluorescence. CGRP treatment induced the increased of H3K27me3 expression in the spinal dorsal horn and cultured microglial cells (BV2) through EZH2. ChIP-seq data indicated that CGRP significantly altered H3K27me3 enrichments on gene promoters in microglia following CGRP treatment, including 173 gaining H3K27me3 and 75 losing this mark, which mostly enriched in regulation of cell growth, phagosome, and inflammation. qRT-PCR verified expressions of representative candidate genes (TRAF3IP2, BCL2L11, ITGAM, DAB2, NLRP12, WNT3, ADAM10) and real-time cell analysis (RTCA) verified microglial proliferation. Additionally, CGRP treatment and CCI increased expressions of ITGAM, ADAM10, MCP-1, and CX3CR1, key mediators of microglial activation in spinal dorsal horn and cultured microglial cells. Such increased effects induced by CCI were suppressed by CGRP antagonist and EZH2 inhibitor, which were concurrently associated with the attenuated mechanical and thermal hyperalgesia in CCI rats. Conclusion Our findings highly indicate that CGRP is implicated in the genesis of neuropathic pain through regulating microglial activation via EZH2-mediated H3K27me3 in the spinal dorsal horn.

Driving effect of BDNF in the spinal dorsal horn on neuropathic pain

2021 ◽  
pp. 135965
Author(s):  
Zhou Wu ◽  
Xie Zhiping ◽  
Li Chengcai ◽  
Zelong Xing ◽  
Xie Shenke ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Spinal Dorsal
Sign in / Sign up

Export Citation Format

Share Document