scholarly journals Injectable Capsaicin for the Management of Pain Due to Osteoarthritis

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 778
Author(s):  
James N. Campbell ◽  
Randall Stevens ◽  
Peter Hanson ◽  
James Connolly ◽  
Diana S. Meske ◽  
...  
Keyword(s):  
Nervous System ◽  
Neuropathic Pain ◽  
Disruptive Effect ◽  
Single Administration ◽  
Trpv1 Channel ◽  
Therapeutic Benefits ◽  
Activation Mechanisms ◽  
Nociceptive Fibers ◽  
Potent Agonist ◽  
Topical Capsaicin

Capsaicin is a potent agonist of the TRPV1 channel, a transduction channel that is highly expressed in nociceptive fibers (pain fibers) throughout the peripheral nervous system. Given the importance of TRPV1 as one of several transduction channels in nociceptive fibers, much research has been focused on the potential therapeutic benefits of using TRPV1 antagonists for the management of pain. However, an antagonist has two limitations. First, an antagonist in principle generally only affects one receptor. Secondly, most antagonists must have an ongoing presence on the receptor to have an effect. Capsaicin overcomes both liabilities by disrupting peripheral terminals of nociceptive fibers that express TRPV1, and thereby affects all of the potential means of activating that pain fiber (not just TRPV1 function). This disruptive effect is dependent on the dose and can occur within minutes. Thus, unlike a typical receptor antagonist, continued bioavailability at the level of the receptor is not necessary. By disrupting the entire terminal of the TRPV1-expressing nociceptive fiber, capsaicin blocks all the activation mechanisms within that fiber, and not just TRPV1 function. Topical capsaicin, an FDA approved treatment for neuropathic pain, addresses pain from abnormal nociceptor activity in the superficial layers of the skin. Effects after a single administration are evident over a period of weeks to months, but in time are fully reversible. This review focuses on the rationale for using capsaicin by injection for painful conditions such as osteoarthritis (OA) and provides an update on studies completed to date.

The Therapeutic Potential of Chemokines in the Treatment of Chemotherapy- Induced Peripheral Neuropathy

2020 ◽  
Vol 21 (3) ◽  
pp. 288-301 ◽  
Author(s):  
Lin Zhou ◽  
Luyao Ao ◽  
Yunyi Yan ◽  
Wanting Li ◽  
Anqi Ye ◽  
...  
Keyword(s):  
Nervous System ◽  
Neuropathic Pain ◽  
Immune System ◽  
Peripheral Neuropathy ◽  
Immune Cell ◽  
Therapeutic Potential ◽  
Chemotherapeutic Agents ◽  
Cell Trafficking ◽  
Mediated Communication ◽  
Novel Therapeutic Strategies

Background: Some of the current challenges and complications of cancer therapy are chemotherapy- induced peripheral neuropathy (CIPN) and the neuropathic pain that are associated with this condition. Many major chemotherapeutic agents can cause neurotoxicity, significantly modulate the immune system and are always accompanied by various adverse effects. Recent evidence suggests that cross-talk occurs between the nervous system and the immune system during treatment with chemotherapeutic agents; thus, an emerging concept is that neuroinflammation is one of the major mechanisms underlying CIPN, as demonstrated by the upregulation of chemokines. Chemokines were originally identified as regulators of peripheral immune cell trafficking, and chemokines are also expressed on neurons and glial cells in the central nervous system. Objective: In this review, we collected evidence demonstrating that chemokines are potential mediators and contributors to pain signalling in CIPN. The expression of chemokines and their receptors, such as CX3CL1/CX3CR1, CCL2/CCR2, CXCL1/CXCR2, CXCL12/CXCR4 and CCL3/CCR5, is altered in the pathological conditions of CIPN, and chemokine receptor antagonists attenuate neuropathic pain behaviour. Conclusion: By understanding the mechanisms of chemokine-mediated communication, we may reveal chemokine targets that can be used as novel therapeutic strategies for the treatment of CIPN.

Preparation of domoic acid analogues using a bioconversion system, and their toxicity in mice

2021 ◽  
Author(s):  
Yukari Maeno ◽  
Yuichi Kotaki ◽  
Ryuta Terada ◽  
Masafumi Hidaka ◽  
Yuko Cho ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Chemical Synthesis ◽  
Glutamate Receptors ◽  
Domoic Acid ◽  
Ionotropic Glutamate Receptors ◽  
The Central Nervous System ◽  
Potent Agonist

Domoic acid (1, DA), a member of the natural kainoid family, is a potent agonist of ionotropic glutamate receptors in the central nervous system. The chemical synthesis of DA and...

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.

Understanding Neuropathic Pain

CNS Spectrums ◽  
2005 ◽  
Vol 10 (4) ◽  
pp. 298-308 ◽  
Author(s):  
Walter Zieglgänsberger ◽  
Achim Berthele ◽  
Thomas R. Tölle
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neuropathic Pain ◽  
Neuronal Excitability ◽  
Traumatic Injury ◽  
Nerve Fibers ◽  
Cellular Events ◽  
Excitatory Neurotransmitters ◽  
The Central Nervous System ◽  
Activity Dependent

AbstractNeuropathic pain is defined as a chronic pain condition that occurs or persists after a primary lesion or dysfunction of the peripheral or central nervous system. Traumatic injury of peripheral nerves also increases the excitability of nociceptors in and around nerve trunks and involves components released from nerve terminals (neurogenic inflammation) and immunological and vascular components from cells resident within or recruited into the affected area. Action potentials generated in nociceptors and injured nerve fibers release excitatory neurotransmitters at their synaptic terminals such as L-glutamate and substance P and trigger cellular events in the central nervous system that extend over different time frames. Short-term alterations of neuronal excitability, reflected for example in rapid changes of neuronal discharge activity, are sensitive to conventional analgesics, and do not commonly involve alterations in activity-dependent gene expression. Novel compounds and new regimens for drug treatment to influence activity-dependent long-term changes in pain transducing and suppressive systems (pain matrix) are emerging.

Central and Peripheral Nervous System

2021 ◽  
Author(s):  
Esther Benedetti ◽  
James Burnett ◽  
Meredith Degnan ◽  
Danielle Horne ◽  
Andres Missair ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Nervous System ◽  
Neuropathic Pain ◽  
Cancer Pain ◽  
Pain Perception ◽  
Visceral Pain ◽  
Influential Factors ◽  
Electrical Transmission ◽  
Somatic Pain ◽  
Spine Pain

The neuronal, chemical, and electrical transmission of pain is a complex and intricate subject that continues to be studied and expounded. This review discusses the relevant physiology and influential factors contributing to the experience and subjective variation in a variety of acute and chronic pain presentations. This review contains 4 figures, 4 tables, and 30 references Keywords: acute pain, chronic pain, somatic pain, neuropathic pain, visceral pain, nociception, pain perception, gender-related pain, cancer pain, spine pain

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