scholarly journals Spinal NGF Restores Opioid Sensitivity in Neuropathic Rats: Possible Role of NGF as a Regulator of CCK-Induced Anti-Opioid Effects

2000 ◽  
Vol 5 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Catherine M Cahill ◽  
Terence J Coderre
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Nerve Injury ◽  
Postnatal Period ◽  
Spontaneous Pain ◽  
Pain Mechanisms ◽  
Nociceptive Neurons ◽  
Nociceptive Transmission ◽  
Chronic Pain Conditions ◽  
Injury Models

The breadth of peripheral effects produced by nerve growth factor (NGF) in nociceptive processing has been well documented. However, less is known about the functional significance of central NGF in nociceptive transmission. The effect of NGF on the nervous system is dependent on the developmental stage. During the prenatal developmental period, NGF is critical for survival of nociceptors; in the postnatal period it regulates the expression of nociceptor phenotype, and in the adult it contributes to pain following an inflammatory insult. The implications for central NGF in the expression and regulation of spinal neuropeptides that are involved in pain mechanisms are reviewed. Knowledge has been gained by studies using peripheral nerve injury models that cause a deprivation of central NGF. These models also give rise to the development of pain syndromes, which encompass spontaneous pain, hyperalgesia and allodynia, routinely referred to as neuropathic pain. These models provide an approach for examining the contribution of central NGF to nociceptive transmission. Chronic pain emanating from a nerve injury is typically refractory to traditional analgesics such as opioids. Recent evidence suggests that supplementation of spinal NGF restores morphine-induced antinociception in an animal model of neuropathic pain. This effect appears to be mediated by alterations in spinal levels of cholecystokinin. The authors hypothesize that NGF is critical in maintaining neurochemical homeostasis in the spinal cord of nociceptive neurons, and that supplementation may be beneficial in restoring and/or maintaining opioid analgesia in chronic pain conditions resulting from traumatic nerve injury.

Neuropathic pain in patients with haemophilia, that is the question

2015 ◽  
Vol 35 (S 01) ◽  
pp. S5-S9 ◽  
Author(s):  
S. Krüger ◽  
T. Hilberg
Keyword(s):  
Rheumatoid Arthritis ◽  
Chronic Pain ◽  
Neuropathic Pain ◽  
Differential Diagnosis ◽  
Pain Management ◽  
Pain Mechanisms ◽  
Number Of Patients ◽  
Paindetect Questionnaire ◽  
Chronic Disorders ◽  
Chronic Pain Conditions

SummaryChronic pain caused by recurrent joint bleedings affects a large number of patients with haemophilia (PwH). The basis of this pain, nociceptive or neuropathic, has not been investigated so far. In other pain-related chronic disorders such as osteoarthritis or rheumatoid arthritis, initial studies showed nociceptive but also neuropathic pain features. 137 PwH and 33 controls (C) completed the painDETECT-questionnaire (pDq), which identifies neuropathic components in a person´s pain profile. Based on the pDq results, a neuropathic pain component is classified as positive, negative or unclear. A positive neuropathic pain component was found in nine PwH, but not in C. In 20 PwH an unclear pDq result was observed. In comparison to C the allocation of pDq results is statistically significant (p≤0.001). Despite various pDq results in PwH and C a similar appraisal pain quality, but on a different level, was determined. Summarising the results, there is a potential risk to misunderstand underlying pain mechanisms in PwH. In chronic pain conditions based on haemophilic arthopathy, a differential diagnosis seems to be unalterable for comprehensive and individualised pain management in PwH.

scholarly journals Relief of neuropathic pain by cell-specific manipulation of nucleus accumbens dopamine D1- and D2-receptor-expressing neurons

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Daisuke Sato ◽  
Michiko Narita ◽  
Yusuke Hamada ◽  
Tomohisa Mori ◽  
Kenichi Tanaka ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Nucleus Accumbens ◽  
Sciatic Nerve ◽  
Nerve Injury ◽  
D2 Receptor ◽  
D1 Receptor ◽  
Cholinergic Interneurons ◽  
Chronic Pain Conditions ◽  
Stimulation Of

AbstractEmerging evidence suggests that the mesolimbic dopaminergic network plays a role in the modulation of pain. As chronic pain conditions are associated with hypodopaminergic tone in the nucleus accumbens (NAc), we evaluated the effects of increasing signaling at dopamine D1/D2-expressing neurons in the NAc neurons in a model of neuropathic pain induced by partial ligation of sciatic nerve. Bilateral microinjection of either the selective D1-receptor (Gs-coupled) agonist Chloro-APB or the selective D2-receptor (Gi-coupled) agonist quinpirole into the NAc partially reversed nerve injury-induced thermal allodynia. Either optical stimulation of D1-receptor-expressing neurons or optical suppression of D2-receptor-expressing neurons in both the inner and outer substructures of the NAc also transiently, but significantly, restored nerve injury-induced allodynia. Under neuropathic pain-like condition, specific facilitation of terminals of D1-receptor-expressing NAc neurons projecting to the VTA revealed a feedforward-like antinociceptive circuit. Additionally, functional suppression of cholinergic interneurons that negatively and positively control the activity of D1- and D2-receptor-expressing neurons, respectively, also transiently elicited anti-allodynic effects in nerve injured animals. These findings suggest that comprehensive activation of D1-receptor-expressing neurons and integrated suppression of D2-receptor-expressing neurons in the NAc may lead to a significant relief of neuropathic pain.

scholarly journals Ketamine for Non-Neuropathic Pain

2021 ◽  
Author(s):  
Subbulakshmi Sundaram ◽  
Ashok Swaminathan Govindarajan
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Complex Regional Pain Syndrome ◽  
Antinociceptive Effect ◽  
Pain Syndrome ◽  
Well Being ◽  
Pain Mechanisms ◽  
Cardiovascular Side Effects ◽  
Chronic Pain Conditions ◽  
Rescue Agent

Chronic pain is one of the leading causes of years lost to disability, as most of the time it is refractory to conventional treatment. Recent advances in understanding the pain mechanisms have favored the use of ketamine as a rescue agent in refractory chronic pain conditions, as it has potential modulating effect on both sensory-discriminative and affective motivational components of pain. Preclinical studies also suggested the antinociceptive effect of sub anesthetic dose of ketamine against central and peripheral neuropathic pain conditions and non-neuropathic pain conditions such as inflammatory and nociceptive pain states. Subanesthetic infusion of ketamine along with adjuvants such as midazolam and clonidine is found to reduce the psychomimetic and cardiovascular side effects of ketamine. Even though the consensus guidelines for intravenous use of ketamine for chronic pain advocate the use of ketamine only for complex regional pain syndrome, various other clinical studies suggested its role in other refractory painful conditions. Hence the present topic focuses specifically on the effect of ketamine on non-neuropathic pain conditions such as complex regional pain syndrome, fibromyalgia, headache, ischemic limb pain, etc. Many studies had shown that ketamine not only reduces the pain scores but also the analgesic medications, which further improves the well-being and quality of life.

scholarly journals Nuclear Factor κB-COX2 Pathway Activation in Non-myelinating Schwann Cells Is Necessary for the Maintenance of Neuropathic Pain in vivo

2022 ◽  
Vol 15 ◽  
Author(s):  
Alison Xiaoqiao Xie ◽  
Sarah Taves ◽  
Ken McCarthy
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Schwann Cells ◽  
Nerve Injury ◽  
Glial Cells ◽  
Nuclear Factor Κb ◽  
Pain Behavior ◽  
Nuclear Factor ◽  
Nociceptive Neurons

Chronic neuropathic pain leads to long-term changes in the sensitivity of both peripheral and central nociceptive neurons. Glial fibrillary acidic protein (GFAP)-positive glial cells are closely associated with the nociceptive neurons including astrocytes in the central nervous system (CNS), satellite glial cells (SGCs) in the sensory ganglia, and non-myelinating Schwann cells (NMSCs) in the peripheral nerves. Central and peripheral GFAP-positive cells are involved in the maintenance of chronic pain through a host of inflammatory cytokines, many of which are under control of the transcription factor nuclear factor κB (NFκB) and the enzyme cyclooxygenase 2 (COX2). To test the hypothesis that inhibiting GFAP-positive glial signaling alleviates chronic pain, we used (1) a conditional knockout (cKO) mouse expressing Cre recombinase under the hGFAP promoter and a floxed COX2 gene to inactivate the COX2 gene specifically in GFAP-positive cells; and (2) a tet-Off tetracycline transactivator system to suppress NFκB activation in GFAP-positive cells. We found that neuropathic pain behavior following spared nerve injury (SNI) significantly decreased in COX2 cKO mice as well as in mice with decreased glial NFκB signaling. Additionally, experiments were performed to determine whether central or peripheral glial NFκB signaling contributes to the maintenance of chronic pain behavior following nerve injury. Oxytetracycline (Oxy), a blood-brain barrier impermeable analog of doxycycline was employed to restrict transgene expression to CNS glia only, leaving peripheral glial signaling intact. Signaling inactivation in central GFAP-positive glia alone failed to exhibit the same analgesic effects as previously observed in animals with both central and peripheral glial signaling inhibition. These data suggest that the NFκB-COX2 signaling pathway in NMSCs is necessary for the maintenance of neuropathic pain in vivo.

Autotomy

2018 ◽  
Author(s):  
Nicholas D. James ◽  
Elizabeth J. Bradbury
Keyword(s):  
Neuropathic Pain ◽  
Peripheral Nerve ◽  
Nerve Injury ◽  
Spontaneous Pain ◽  
Self Mutilation ◽  
Peripheral Nerve Lesions ◽  
Underlying Causes ◽  
Ectopic Firing ◽  
Injury Models ◽  
Anaesthesia Dolorosa

The landmark paper discussed in this chapter is ‘Autotomy following peripheral nerve lesions: Experimental anaesthesia dolorosa’, published by Wall et al. in 1979. This paper was the culmination of a series of studies in which Wall, together with a number of colleagues, investigated the underlying causes of neuropathic pain following peripheral nerve injury. In this paper, the authors used a variety of nerve injury models to show that the extent of resultant anaesthesia combined with ectopic firing from damaged axons in nerve-end neuromas correlated with the severity of self-mutilation (termed ‘autotomy’) observed in the affected hindlimb. The authors therefore suggested that these simple models might be suitable for studies of the prevention of irritations originating from chronic lesions of peripheral nerves. Indeed, this proved to be the case, sparking the development of numerous animal models of spontaneous pain following nerve injury and spawning a new field of neuropathic pain research.

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.

HCN2 ion channels: basic science opens up possibilities for therapeutic intervention in neuropathic pain

2016 ◽  
Vol 473 (18) ◽  
pp. 2717-2736 ◽  
Author(s):  
Christoforos Tsantoulas ◽  
Elizabeth R. Mooney ◽  
Peter A. McNaughton
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Ion Channels ◽  
Warning Signal ◽  
Sensory Nerves ◽  
Nociceptive Neurons ◽  
Pain Syndromes ◽  
Medical Need ◽  
Pathological Pain ◽  
Genetic Deletion

Nociception — the ability to detect painful stimuli — is an invaluable sense that warns against present or imminent damage. In patients with chronic pain, however, this warning signal persists in the absence of any genuine threat and affects all aspects of everyday life. Neuropathic pain, a form of chronic pain caused by damage to sensory nerves themselves, is dishearteningly refractory to drugs that may work in other types of pain and is a major unmet medical need begging for novel analgesics. Hyperpolarisation-activated cyclic nucleotide (HCN)-modulated ion channels are best known for their fundamental pacemaker role in the heart; here, we review data demonstrating that the HCN2 isoform acts in an analogous way as a ‘pacemaker for pain’, in that its activity in nociceptive neurons is critical for the maintenance of electrical activity and for the sensation of chronic pain in pathological pain states. Pharmacological block or genetic deletion of HCN2 in sensory neurons provides robust pain relief in a variety of animal models of inflammatory and neuropathic pain, without any effect on normal sensation of acute pain. We discuss the implications of these findings for our understanding of neuropathic pain pathogenesis, and we outline possible future opportunities for the development of efficacious and safe pharmacotherapies in a range of chronic pain syndromes.

scholarly journals Plasticity-Related PKMζSignaling in the Insular Cortex Is Involved in the Modulation of Neuropathic Pain after Nerve Injury

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Jeongsoo Han ◽  
Minjee Kwon ◽  
Myeounghoon Cha ◽  
Motomasa Tanioka ◽  
Seong-Karp Hong ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Neuropathic Pain ◽  
Nerve Injury ◽  
Neural Plasticity ◽  
Mechanical Allodynia ◽  
Insular Cortex ◽  
Long Term Potentiation ◽  
Inhibitory Peptide ◽  
Term Potentiation ◽  
Potential Applications

The insular cortex (IC) is associated with important functions linked with pain and emotions. According to recent reports, neural plasticity in the brain including the IC can be induced by nerve injury and may contribute to chronic pain. Continuous active kinase, protein kinase Mζ(PKMζ), has been known to maintain the long-term potentiation. This study was conducted to determine the role of PKMζin the IC, which may be involved in the modulation of neuropathic pain. Mechanical allodynia test and immunohistochemistry (IHC) of zif268, an activity-dependent transcription factor required for neuronal plasticity, were performed after nerve injury. Afterζ-pseudosubstrate inhibitory peptide (ZIP, a selective inhibitor of PKMζ) injection, mechanical allodynia test and immunoblotting of PKMζ, phospho-PKMζ(p-PKMζ), and GluR1 and GluR2 were observed. IHC demonstrated that zif268 expression significantly increased in the IC after nerve injury. Mechanical allodynia was significantly decreased by ZIP microinjection into the IC. The analgesic effect lasted for 12 hours. Moreover, the levels of GluR1, GluR2, and p-PKMζwere decreased after ZIP microinjection. These results suggest that peripheral nerve injury induces neural plasticity related to PKMζand that ZIP has potential applications for relieving chronic pain.

Spontaneous pain in partial nerve injury models of neuropathy and the role of nociceptive sensory cover

2012 ◽  
Vol 236 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Pini Koplovitch ◽  
Anne Minert ◽  
Marshall Devor
Keyword(s):  
Nerve Injury ◽  
Spontaneous Pain ◽  
Injury Models
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