scholarly journals Activity of novel lipid glycine transporter inhibitors on synaptic signalling in the dorsal horn of the spinal cord

2018 ◽  
Vol 175 (12) ◽  
pp. 2337-2347 ◽  
Author(s):  
Bryony L Winters ◽  
Tristan Rawling ◽  
Robert J Vandenberg ◽  
Macdonald J Christie ◽  
Rebecca F Bhola ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Glycine Transporter ◽  
Synaptic Signalling

scholarly journals Spinal Cord Glycine Transporter 2 Mediates Bilateral ST35 Acupoints Sensitization in Rats with Knee Osteoarthritis

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Fuhai Bai ◽  
Yongyuan Ma ◽  
Haiyun Guo ◽  
Yuheng Li ◽  
Feifei Xu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Mast Cell ◽  
Knee Osteoarthritis ◽  
Dorsal Horn ◽  
Intrathecal Administration ◽  
Mast Cell Degranulation ◽  
Spinal Cord Dorsal Horn ◽  
Glycine Transporter ◽  
Mechanical Threshold ◽  
Glycine Transporter 2

The concept of “acupoint sensitization” refers to the functional status of acupoint switches from silent to active under pathological conditions. In clinic, acupoint sensitization provides important guidance for acupoints selection in different diseases. However, the mechanism behind this phenomenon remains unclear. We generated a model of knee osteoarthritis (KOA) by intra-articular injection of monosodium iodoacetate (MIA) into the left knee of rats. The paw withdrawal mechanical threshold (PWMT) and the total number of mast cells as well as mast cell degranulation rate (MCDR) of acupoint tissue were used to test whether the acupoints were sensitized. The results showed that KOA resulted in a reduced mechanical threshold and elevated total number of mast cell as well as mast cell degranulation rate at bilateral ST35 (Dubi) but not GB37 (Guangming) or nonacupoint area. The acupoint sensitization was accompanied by upregulation of glycine transporter 2 (GlyT2) and reduction of extracellular glycine levels in the bilateral dorsal horns of the spinal cord at L3-5. Selective inhibition of GlyT2 or intrathecal administration of glycine attenuated ST35 acupoint sensitization. The sensitization of bilateral ST35 was blocked after intraspinal GlyT2 short hairpin (sh) RNA (GlyT2-shRNA) microinjection to specifically downregulate GlyT2 expression in the left side (ipsilateral) L3-5 spinal cord dorsal horn before MIA injection. Moreover, electroacupuncture (EA) stimulation at ST35 ameliorated articular pathological lesions and improved KOA-related pain behaviors. GlyT2-shRNA injection reversed EA-induced pain relief but not EA-induced reduction of joint lesions. Overall, this study demonstrated that spinal GlyT2, especially elevated GlyT2 expression in the ipsilateral dorsal horn of the spinal cord, is a crucial mediator of ST35 acupoint sensitization in KOA rats.

scholarly journals Inhibition of Glycine Re-Uptake: A Potential Approach for Treating Pain by Augmenting Glycine-Mediated Spinal Neurotransmission and Blunting Central Nociceptive Signaling

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 864
Author(s):  
Christopher L. Cioffi
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Therapeutic Potential ◽  
Opioid Analgesic ◽  
Critical Role ◽  
Analgesic Efficacy ◽  
Standard Of Care ◽  
Current Standard ◽  
Glycine Transporters ◽  
Pathological Pain

Among the myriad of cellular and molecular processes identified as contributing to pathological pain, disinhibition of spinal cord nociceptive signaling to higher cortical centers plays a critical role. Importantly, evidence suggests that impaired glycinergic neurotransmission develops in the dorsal horn of the spinal cord in inflammatory and neuropathic pain models and is a key maladaptive mechanism causing mechanical hyperalgesia and allodynia. Thus, it has been hypothesized that pharmacological agents capable of augmenting glycinergic tone within the dorsal horn may be able to blunt or block aberrant nociceptor signaling to the brain and serve as a novel class of analgesics for various pathological pain states. Indeed, drugs that enhance dysfunctional glycinergic transmission, and in particular inhibitors of the glycine transporters (GlyT1 and GlyT2), are generating widespread interest as a potential class of novel analgesics. The GlyTs are Na+/Cl−-dependent transporters of the solute carrier 6 (SLC6) family and it has been proposed that the inhibition of them presents a possible mechanism by which to increase spinal extracellular glycine concentrations and enhance GlyR-mediated inhibitory neurotransmission in the dorsal horn. Various inhibitors of both GlyT1 and GlyT2 have demonstrated broad analgesic efficacy in several preclinical models of acute and chronic pain, providing promise for the approach to deliver a first-in-class non-opioid analgesic with a mechanism of action differentiated from current standard of care. This review will highlight the therapeutic potential of GlyT inhibitors as a novel class of analgesics, present recent advances reported for the field, and discuss the key challenges associated with the development of a GlyT inhibitor into a safe and effective agent to treat pain.

scholarly journals SUR1, newly expressed in astrocytes, mediates neuropathic pain in a mouse model of peripheral nerve injury

2021 ◽  
Vol 17 ◽  
pp. 174480692110066
Author(s):  
Orest Tsymbalyuk ◽  
Volodymyr Gerzanich ◽  
Aaida Mumtaz ◽  
Sanketh Andhavarapu ◽  
Svetlana Ivanova ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Sciatic Nerve ◽  
Peripheral Nerve ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Peripheral Nerve Injury ◽  
Thermal Sensitivity ◽  
Gradual Improvement ◽  
Pain Behaviors

Background Neuropathic pain following peripheral nerve injury (PNI) is linked to neuroinflammation in the spinal cord marked by astrocyte activation and upregulation of interleukin 6 (IL -6 ), chemokine (C-C motif) ligand 2 (CCL2) and chemokine (C-X-C motif) ligand 1 (CXCL1), with inhibition of each individually being beneficial in pain models. Methods Wild type (WT) mice and mice with global or pGfap-cre- or pGFAP-cre/ERT2-driven Abcc8/SUR1 deletion or global Trpm4 deletion underwent unilateral sciatic nerve cuffing. WT mice received prophylactic (starting on post-operative day [pod]-0) or therapeutic (starting on pod-21) administration of the SUR1 antagonist, glibenclamide (10 µg IP) daily. We measured mechanical and thermal sensitivity using von Frey filaments and an automated Hargreaves method. Spinal cord tissues were evaluated for SUR1-TRPM4, IL-6, CCL2 and CXCL1. Results Sciatic nerve cuffing in WT mice resulted in pain behaviors (mechanical allodynia, thermal hyperalgesia) and newly upregulated SUR1-TRPM4 in dorsal horn astrocytes. Global and pGfap-cre-driven Abcc8 deletion and global Trpm4 deletion prevented development of pain behaviors. In mice with Abcc8 deletion regulated by pGFAP-cre/ERT2, after pain behaviors were established, delayed silencing of Abcc8 by tamoxifen resulted in gradual improvement over the next 14 days. After PNI, leakage of the blood-spinal barrier allowed entry of glibenclamide into the affected dorsal horn. Daily repeated administration of glibenclamide, both prophylactically and after allodynia was established, prevented or reduced allodynia. The salutary effects of glibenclamide on pain behaviors correlated with reduced expression of IL-6, CCL2 and CXCL1 by dorsal horn astrocytes. Conclusion SUR1-TRPM4 may represent a novel non-addicting target for neuropathic pain.

scholarly journals Delta Opioid Receptors Presynaptically Regulate Cutaneous Mechanosensory Neuron Input to the Spinal Cord Dorsal Horn

Neuron ◽  
2014 ◽  
Vol 81 (6) ◽  
pp. 1443 ◽  
Author(s):  
Rita Bardoni ◽  
Vivianne L. Tawfik ◽  
Dong Wang ◽  
Amaury François ◽  
Carlos Solorzano ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Opioid Receptors ◽  
Spinal Cord Dorsal Horn ◽  
Mechanosensory Neuron ◽  
Delta Opioid Receptors ◽  
Spinal Cord Dorsal

How to Do It: Microsurgical DREZotomy for Pain After Brachial Plexus Injury: 2-Dimensional Operative Video

2021 ◽  
Author(s):  
Manon Duraffourg ◽  
Andrei Brinzeu ◽  
Marc Sindou
Keyword(s):  
Spinal Cord ◽  
Pain Relief ◽  
Brachial Plexus ◽  
Dorsal Horn ◽  
Brachial Plexus Injury ◽  
Dorsal Column ◽  
Motor Deficit ◽  
Complete Disappearance ◽  
Burning Pain ◽  
Root Entry Zone

Abstract More than three-quarters of victims of brachial plexus injury suffer from refractory neuropathic pain.1-6 Main putative mechanism is paroxysmal hyperactivity in the dorsal horn neurons at the dorsal root entry zone (DREZ) as demonstrated by microelectrode recordings in animal models7 and patients.8 Pain relief can be achieved by lesioning the responsible neurons in the spinal cord segments with avulsed rootlets.9,10  This video illustrates the technique for microsurgical DREZotomy.11,12 A C3-C7 hemilaminectomy is performed to access the C4-Th1 medullary segments. After opening the dura and arachnoid, and freeing the cord from arachnoid adhesions, the dorsolateral sulcus is identified. Identification can be difficult when the spinal cord is distorted and/or has a loss of substance. The dorsolateral sulcus is then opened with a microknife, so that microcoagulations are performed: 4 mm deep, at 35° angle in the axis of the dorsal horn, every millimeter in a dotted fashion along the avulsed segments. Care should be taken not to damage the corticospinal tract, laterally, and the dorsal column, medially.  The patient consents to the procedure. In the presented case, surgery led to complete disappearance of the paroxysmal pain and reduced the background of burning pain to a bearable level without the need of opioid medication. There was no motor deficit or ataxia in the ipsilateral lower limb postoperatively. According to Kaplan-Meier analysis at 10 yr follow-up, in our overall series, microsurgical DREZotomy achieved total pain relief without any medication in 60% of patients, and in 85% without the need for opioids.10,13-15  Microelectrode recording at 1:26 reproduced from Guenot et al7 with permission from JNSPG.

Acetaminophen Inhibits Spinal Prostaglandin E2Release after Peripheral Noxious Stimulation 

1999 ◽  
Vol 91 (1) ◽  
pp. 231-239 ◽  
Author(s):  
Uta S. Muth-Selbach ◽  
Irmgard Tegeder ◽  
Kay Brune ◽  
Gerd Geisslinger
Keyword(s):  
Spinal Cord ◽  
Urinary Excretion ◽  
Dorsal Horn ◽  
Formalin Test ◽  
Intraperitoneal Administration ◽  
Noxious Stimulation ◽  
Cyclooxygenase Inhibitor ◽  
Nociceptive Processing ◽  
Pge2 Release

Background Prostaglandin play a pivotal role in spinal nociceptive processing. At therapeutic concentrations, acetaminophen is not a cyclooxygenase inhibitor. inhibitor. Thus, it is antinociceptive without having antiinflammatory or gastrointestinal toxic effects. This study evaluated the role of spinal prostaglandin E2 (PGE2) in antinociception produced by intraperitoneally administered acetaminophen. Methods The PGE2 concentrations in the dorsal horn of the spinal cord were measured after formalin was injected into the hind paw of rats. The effect of antinociceptive doses of acetaminophen (100, 200, and 300 mg/kg given intraperitoneally) on PGE2 levels and flinching behavior was monitored Spinal PGE2 and acetaminophen concentrations were obtained by microdialysis using a probe that was implanted transversely through the dorsal horn of the spinal cord at L4. Furthermore, the effects of acetaminophen on urinary prostaglandin excretion were determined. Results Intraperitoneal administration of acetaminophen resulted in a significant decrease in spinal PGE2 release that was associated with a significant reduction in the flinching behavior in the formalin test Acetaminophen was distributed rapidly into the spinal cord with maximum dialysate concentrations 4560 min after intraperitoneal administration. Urinary excretion of prostanoids (PGE2, PGF2alpha, and 6-keto-PGF1alpha) was not significantly altered after acetaminophen administration. Conclusions The data confirm the importance of PGE2 in spinal nociceptive processing. The results suggest that antinociception after acetaminophen administration is mediated, at least in part, by inhibition of spinal PGE2 release. The mechanism, however, remains unknown. The finding that urinary excretion of prostaglandins was not affected might explain why acetaminophen is antinociceptive but does not compromise renal safety.

scholarly journals Neuron-specific spinal cord translatomes reveal a neuropeptide code for mouse dorsal horn excitatory neurons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Rani Das Gupta ◽  
Louis Scheurer ◽  
Pawel Pelczar ◽  
Hendrik Wildner ◽  
Hanns Ulrich Zeilhofer
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Functional Organization ◽  
Affinity Purification ◽  
Expression Patterns ◽  
Inhibitory Neurons ◽  
Dorsal Horn Neurons ◽  
Expression Of Genes ◽  
Excitatory Neurons ◽  
Genes Encoding

AbstractThe spinal dorsal horn harbors a sophisticated and heterogeneous network of excitatory and inhibitory neurons that process peripheral signals encoding different sensory modalities. Although it has long been recognized that this network is crucial both for the separation and the integration of sensory signals of different modalities, a systematic unbiased approach to the use of specific neuromodulatory systems is still missing. Here, we have used the translating ribosome affinity purification (TRAP) technique to map the translatomes of excitatory glutamatergic (vGluT2+) and inhibitory GABA and/or glycinergic (vGAT+ or Gad67+) neurons of the mouse spinal cord. Our analyses demonstrate that inhibitory and excitatory neurons are not only set apart, as expected, by the expression of genes related to the production, release or re-uptake of their principal neurotransmitters and by genes encoding for transcription factors, but also by a differential engagement of neuromodulator, especially neuropeptide, signaling pathways. Subsequent multiplex in situ hybridization revealed eleven neuropeptide genes that are strongly enriched in excitatory dorsal horn neurons and display largely non-overlapping expression patterns closely adhering to the laminar and presumably also functional organization of the spinal cord grey matter.

scholarly journals Role of the immune system in neuropathic pain

2019 ◽  
Vol 20 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Marzia Malcangio
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Nervous System ◽  
Neuropathic Pain ◽  
Immune System ◽  
Peripheral Nerve ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Immune Cells ◽  
Peripheral Nerve Injury

AbstractBackgroundAcute pain is a warning mechanism that exists to prevent tissue damage, however pain can outlast its protective purpose and persist beyond injury, becoming chronic. Chronic Pain is maladaptive and needs addressing as available medicines are only partially effective and cause severe side effects. There are profound differences between acute and chronic pain. Dramatic changes occur in both peripheral and central pathways resulting in the pain system being sensitised, thereby leading to exaggerated responses to noxious stimuli (hyperalgesia) and responses to non-noxious stimuli (allodynia).Critical role for immune system cells in chronic painPreclinical models of neuropathic pain provide evidence for a critical mechanistic role for immune cells in the chronicity of pain. Importantly, human imaging studies are consistent with preclinical findings, with glial activation evident in the brain of patients experiencing chronic pain. Indeed, immune cells are no longer considered to be passive bystanders in the nervous system; a consensus is emerging that, through their communication with neurons, they can both propagate and maintain disease states, including neuropathic pain. The focus of this review is on the plastic changes that occur under neuropathic pain conditions at the site of nerve injury, the dorsal root ganglia (DRG) and the dorsal horn of the spinal cord. At these sites both endothelial damage and increased neuronal activity result in recruitment of monocytes/macrophages (peripherally) and activation of microglia (centrally), which release mediators that lead to sensitisation of neurons thereby enabling positive feedback that sustains chronic pain.Immune system reactions to peripheral nerve injuriesAt the site of peripheral nerve injury following chemotherapy treatment for cancer for example, the occurrence of endothelial activation results in recruitment of CX3C chemokine receptor 1 (CX3CR1)-expressing monocytes/macrophages, which sensitise nociceptive neurons through the release of reactive oxygen species (ROS) that activate transient receptor potential ankyrin 1 (TRPA1) channels to evoke a pain response. In the DRG, neuro-immune cross talk following peripheral nerve injury is accomplished through the release of extracellular vesicles by neurons, which are engulfed by nearby macrophages. These vesicles deliver several determinants including microRNAs (miRs), with the potential to afford long-term alterations in macrophages that impact pain mechanisms. On one hand the delivery of neuron-derived miR-21 to macrophages for example, polarises these cells towards a pro-inflammatory/pro-nociceptive phenotype; on the other hand, silencing miR-21 expression in sensory neurons prevents both development of neuropathic allodynia and recruitment of macrophages in the DRG.Immune system mechanisms in the central nervous systemIn the dorsal horn of the spinal cord, growing evidence over the last two decades has delineated signalling pathways that mediate neuron-microglia communication such as P2X4/BDNF/GABAA, P2X7/Cathepsin S/Fractalkine/CX3CR1, and CSF-1/CSF-1R/DAP12 pathway-dependent mechanisms.Conclusions and implicationsDefinition of the modalities by which neuron and immune cells communicate at different locations of the pain pathway under neuropathic pain states constitutes innovative biology that takes the pain field in a different direction and provides opportunities for novel approaches for the treatment of chronic pain.

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