Ion channels in nociceptors

G Protein-Coupled Receptors and Ion Channels Involvement in Cisplatin-Induced Peripheral Neuropathy: A Review of Preclinical Studies

Cisplatin is a platinum-based chemotherapy drug widely used to treat various solid tumours. Although it is effective in anti-cancer therapy, many patients develop peripheral neuropathy during and after cisplatin treatment. Peripheral neuropathy results from lesions or diseases in the peripheral somatosensory nervous system and is a significant cause of debilitation and suffering in patients. In recent years, preclinical studies have been conducted to elucidate the mechanisms involved in chemotherapy-induced peripheral neuropathic pain, as well as to promote new therapeutic targets since current treatments are ineffective and are associated with adverse effects. G-protein coupled receptors and ion channels play a significant role in pain processing and may represent promising targets for improving the management of cisplatin-induced neuropathic pain. This review describes the role of G protein-coupled receptors and ion channels in cisplatin-induced pain, analysing preclinical experimental studies that investigated the role of each receptor subtype in the modulation of cisplatin-induced pain.

A Manifesto in Defense of Pain Complexity: A Critical Review of Essential Insights in Pain Neuroscience

Chronic pain has increasingly become a significant health challenge, not just as a symptomatic manifestation but also as a pathological condition with profound socioeconomic implications. Despite the expansion of medical interventions, the prevalence of chronic pain remains remarkably persistent, prompting a turn towards non-pharmacological treatments, such as therapeutic education, exercise, and cognitive-behavioral therapy. With the advent of cognitive neuroscience, pain is often presented as a primary output derived from the brain, aligning with Engel's Biopsychosocial Model that views disease not solely from a biological perspective but also considering psychological and social factors. This paradigm shift brings forward potential misconceptions and over-simplifications. The current review delves into the intricacies of nociception and pain perception. It questions long-standing beliefs like the cerebral-centric view of pain, the forgotten role of the peripheral nervous system in pain chronification, misconceptions around central sensitization syndromes, the controversy about the existence of a dedicated pain neuromatrix, the consciousness of the pain experience, and the possible oversight of factors beyond the nervous system. In re-evaluating these aspects, the review emphasizes the critical need for understanding the complexity of pain, urging the scientific and clinical community to move beyond reductionist perspectives and consider the multifaceted nature of this phenomenon.

A Rare Skeletal Disorder, Fibrous Dysplasia: A Review of Its Pathogenesis and Therapeutic Prospects

Fibrous dysplasia (FD) is a rare, non-hereditary skeletal disorder characterized by its chronic course of non-neoplastic fibrous tissue buildup in place of healthy bone. A myriad of factors have been associated with its onset and progression. Perturbation of cell-cell signaling networks and response outputs leading to disrupted building blocks, incoherent multi-level organization, and loss of rigid structural motifs in mineralized tissues are factors that have been identified to participate in FD induction. In more recent years, novel insights into the unique biology of FD are transforming our understandings of its pathology, natural discourse of the disease, and treatment prospects. Herein, we built upon existing knowledge with recent findings to review clinical, etiologic, and histological features of FD and discussed known and potential mechanisms underlying FD manifestations. Subsequently, we ended on a note of optimism by highlighting emerging therapeutic approaches aimed at either halting or ameliorating disease progression.

Multi-target modulation of ion channels underlying the analgesic effects of α-mangostin in dorsal root ganglion neurons

BACKGROUND

α-Mangostin is a xanthone isolated from the pericarps of mangosteen fruit with, and has analgesic properties. Although the effects suggest an interaction of α-mangostin with ion channels in the nociceptive neurons, electrophysiological investigation of the underlying mechanism has not been performed.

HYPOTHESIS

We hypothesized that α-Mangostin exerts its analgesic effects by modulating the activity of various ion channels in dorsal root ganglion (DRG) neurons.

METHODS

We performed a whole-cell patch clamp study using mouse DRG neurons, HEK293T cells overexpressing targeted ion channels, and ND7/23 cells. Molecular docking (MD) and in silico absorption, distribution, metabolism, and excretion (ADME) analyses were conducted to obtain further insights into the binding sites and pharmacokinetics, respectively.

RESULTS

Application of α-mangostin (1-3 µM) hyperpolarized the resting membrane potential (RMP) of small-sized DRG neurons by increasing background K⁺ conductance and thereby inhibited action potential generation. At micromolar levels, α-mangostin activates TREK-1, TREK-2, or TRAAK, members of the two-pore domain K⁺ channel (K2P) family known to be involved in RMP formation in DRG neurons. Furthermore, capsaicin-induced TRPV1 currents were potently inhibited by α-mangostin (0.43 ± 0.27 µM), and partly suppressed tetrodotoxin-sensitive voltage-gated Na⁺ channel (Na_V) currents. MD simulation revealed that multiple oxygen atoms in α-mangostin may form stable hydrogen bonds with TREKs, TRAAK, TRPV1, and Na_V channels. In silico ADME tests suggested that α-mangostin may satisfy the drug-likeness properties without penetrating the blood-brain barrier.

CONCLUSION

The analgesic properties of α-mangostin might be mediated by the multi-target modulation of ion channels, including TREK/TRAAK activation, TRPV1 inhibition, and reduction of the tetrodotoxin-sensitive Na_V current. The findings suggest that the phytochemical can be a multi-ion channel-targeting drug and an alternative drug for effective pain management.

Multiple Effects of Echinochrome A on Selected Ion Channels Implicated in Skin Physiology

Echinochrome A (Ech A), a naphthoquinoid pigment from sea urchins, is known to have anti-inflammatory and analgesic effects that have been suggested to be mediated by antioxidant activity and intracellular signaling modulation. In addition to these mechanisms, the ion channels in keratinocytes, immune cells, and nociceptive neurons may be the target for the pharmacological effects. Here, using the patch clamp technique, we investigated the effects of Ech A on the Ca²⁺-permeable TRPV3, TRPV1 and Orai1 channels and the two-pore domain K⁺ (K2P) channels (TREK/TRAAK, TASK-1, and TRESK) overexpressed in HEK 293 cells. Ech A inhibited both the TRPV3 and Orai1 currents, with IC₅₀ levels of 2.1 and 2.4 μM, respectively. The capsaicin-activated TRPV1 current was slightly augmented by Ech A. Ech A alone did not change the amplitude of the TREK-2 current (I_TREK2), but pretreatments with Ech A markedly facilitated I_TREK2 activation by 2-APB, arachidonic acid (AA), and acidic extracellular pH (pH_e). Similar facilitation effects of Ech A on TREK-1 and TRAAK were observed when they were stimulated with 2-APB and AA, respectively. On the contrary, Ech A did not affect the TRESK and TASK-1 currents. Interestingly, the I_TREK2 maximally activated by the combined application of 2-APB and Ech A was not inhibited by norfluoxetine but was still completely inhibited by ruthenium red. The selective loss of sensitivity to norfluoxetine suggested an altered molecular conformation of TREK-2 by Ech A. We conclude that the Ech A-induced inhibition of the Ca²⁺-permeable cation channels and the facilitation of the TREK/TRAAK K2P channels may underlie the analgesic and anti-inflammatory effects of Ech A.

In silico Identification of Key Factors Driving the Response of Muscle Sensory Neurons to Noxious Stimuli

Nociceptive nerve endings embedded in muscle tissue transduce peripheral noxious stimuli into an electrical signal [i.e., an action potential (AP)] to initiate pain sensations. A major contributor to nociception from the muscles is mechanosensation. However, due to the heterogeneity in the expression of proteins, such as ion channels, pumps, and exchangers, on muscle nociceptors, we currently do not know the relative contributions of different proteins and signaling molecules to the neuronal response due to mechanical stimuli. In this study, we employed an integrated approach combining a customized experimental study in mice with a computational model to identify key proteins that regulate mechanical nociception in muscles. First, using newly collected data from somatosensory recordings in mouse hindpaw muscles, we developed and then validated a computational model of a mechanosensitive mouse muscle nociceptor. Next, by performing global sensitivity analyses that simulated thousands of nociceptors, we identified three ion channels (among the 17 modeled transmembrane proteins and four endoplasmic reticulum proteins) as potential regulators of the nociceptor response to mechanical forces in both the innocuous and noxious range. Moreover, we found that simulating single knockouts of any of the three ion channels, delayed rectifier voltage-gated K⁺ channel (Kv1.1) or mechanosensitive channels Piezo2 or TRPA1, considerably altered the excitability of the nociceptor (i.e., each knockout increased or decreased the number of triggered APs compared to when all channels were present). These results suggest that altering expression of the gene encoding Kv1.1, Piezo2, or TRPA1 might regulate the response of mechanosensitive muscle nociceptors.

Selective Expression of a SNARE-Cleaving Protease in Peripheral Sensory Neurons Attenuates Pain-Related Gene Transcription and Neuropeptide Release

Chronic pain is a leading health and socioeconomic problem and an unmet need exists for long-lasting analgesics. SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) are required for neuropeptide release and noxious signal transducer surface trafficking, thus, selective expression of the SNARE-cleaving light-chain protease of botulinum neurotoxin A (LCA) in peripheral sensory neurons could alleviate chronic pain. However, a safety concern to this approach is the lack of a sensory neuronal promoter to prevent the expression of LCA in the central nervous system. Towards this, we exploit the unique characteristics of Pirt (phosphoinositide-interacting regulator of TRP), which is expressed in peripheral nociceptive neurons. For the first time, we identified a Pirt promoter element and cloned it into a lentiviral vector driving transgene expression selectively in peripheral sensory neurons. Pirt promoter driven-LCA expression yielded rapid and concentration-dependent cleavage of SNAP-25 in cultured sensory neurons. Moreover, the transcripts of pain-related genes (TAC1, tachykinin precursor 1; CALCB, calcitonin gene-related peptide 2; HTR3A, 5-hydroxytryptamine receptor 3A; NPY2R, neuropeptide Y receptor Y2; GPR52, G protein-coupled receptor 52; SCN9A, sodium voltage-gated channel alpha subunit 9; TRPV1 and TRPA1, transient receptor potential cation channel subfamily V member 1 and subfamily A member 1) in pro-inflammatory cytokines stimulated sensory neurons were downregulated by viral mediated expression of LCA. Furthermore, viral expression of LCA yielded long-lasting inhibition of pain mediator release. Thus, we show that the engineered Pirt-LCA virus may provide a novel means for long lasting pain relief.

Analgesia for Sheep in Commercial Production: Where to Next?

Simple Summary

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on industry to alleviate pain associated with husbandry practices, injury and illness. Although a number of analgesic solutions are now available for sheep, providing some amelioration of the acute pain responses, this review has highlighted a number of potential areas for further research.

Abstract

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.

Peripheral neuroimmune interactions: selected review and some clinical implications

Purpose

To provide a brief and focused review on peripheral neuroimmune interactions and their implications for some clinical disorders.

Methods

Narrative review of the literature including of English-language articles published between 1985 and 2021 using PubMed and MEDLINE.

Results

Many studies on experimental models and in vitro indicate that there are close interactions between the neural and immune systems. Processes from sensory afferents and autonomic efferents co-localize with immune cells and interact at discrete anatomical sites forming neuroimmune units. These neuroimmune interactions are bidirectional and mediated by a wide range of soluble factors including neuropeptides, classical neurotransmitters, cytokines, and other molecules that mediate complex cross-talk among nerves and immune cells. Small-diameter sensory afferents express a wide range of receptors that respond directly to tissue damage or pathogen signals and to chemokines, cytokines, or other molecules released from immune cells. Reciprocally, immune cells respond to neurotransmitters released from nociceptive and autonomic fibers. Neuroimmune interactions operate both at peripheral tissues and at the level of the central nervous system. Both centrally and peripherally, glial cells have a major active role in this bidirectional communication.

Conclusions

Peripheral neuroimmune interactions are complex and importantly contribute to the pathophysiology of several disorders, including skin, respiratory, and intestinal inflammatory disorders typically associated with pain and altered barrier function. These interactions may be relevant for persistence of symptoms in disorders associated with intense immune activation.

Pain in Axial Spondyloarthritis: Insights from Immunology and Brain Imaging

Inflammatory back pain is characteristic of spondyloarthritis (SpA); however, this pain may not respond to treatment with NSAIDs or biologics. Pain is multifactorial and a combination of mechanical and inflammatory factors. A growing body of literature examines the impact of emotions on pain in SpA; many patients with this condition suffer from depression and fibromyalgia. Advanced imaging techniques can investigate the interplay of various brain networks in pain perception. Animal models have helped understand the interplay between the immune and nervous systems in pain generation and have highlighted differences in pain perception between the sexes.

Prioritizing Pain-Associated Targets with Machine Learning

While hundreds of genes have been associated with pain, much of the molecular mechanisms of pain remain unknown. As a result, current analgesics are limited to few clinically validated targets. Here, we trained a machine learning (ML) ensemble model to predict new targets for 17 categories of pain. The model utilizes features from transcriptomics, proteomics, and gene ontology to prioritize targets for modulating pain. We focused on identifying novel G-protein-coupled receptors (GPCRs), ion channels, and protein kinases because these proteins represent the most successful drug target families. The performance of the model to predict novel pain targets is 0.839 on average based on AUROC, while the predictions for arthritis had the highest accuracy (AUROC = 0.929). The model predicts hundreds of novel targets for pain; for example, GPR132 and GPR109B are highly ranked GPCRs for rheumatoid arthritis. Overall, gene-pain association predictions cluster into three groups that are enriched for cytokine, calcium, and GABA-related cell signaling pathways. These predictions can serve as a foundation for future experimental exploration to advance the development of safer and more effective analgesics.

Excitation properties of computational models of unmyelinated peripheral axons

Biophysically based computational models of nerve fibers are important tools for designing electrical stimulation therapies, investigating drugs that affect ion channels, and studying diseases that affect neurons. Although peripheral nerves are primarily composed of unmyelinated axons (i.e., C-fibers), most modeling efforts focused on myelinated axons. We implemented the single-compartment model of vagal afferents from Schild et al. (1994) (Schild JH, Clark JW, Hay M, Mendelowitz D, Andresen MC, Kunze DL. J Neurophysiol 71: 2338-2358, 1994) and extended the model into a multicompartment axon, presenting the first cable model of a C-fiber vagal afferent. We also implemented the updated parameters from the Schild and Kunze (1997) model (Schild JH, Kunze DL. J Neurophysiol 78: 3198-3209, 1997). We compared the responses of these novel models with those of three published models of unmyelinated axons (Rattay F, Aberham M. IEEE Trans Biomed Eng 40: 1201-1209, 1993; Sundt D, Gamper N, Jaffe DB. J Neurophysiol 114: 3140-3153, 2015; Tigerholm J, Petersson ME, Obreja O, Lampert A, Carr R, Schmelz M, Fransén E. J Neurophysiol 111: 1721-1735, 2014) and with experimental data from single-fiber recordings. Comparing the two models by Schild et al. (1994, 1997) revealed that differences in rest potential and action potential shape were driven by changes in maximum conductances rather than changes in sodium channel dynamics. Comparing the five model axons, the conduction speeds and strength-duration responses were largely within expected ranges, but none of the models captured the experimental threshold recovery cycle-including a complete absence of late subnormality in the models-and their action potential shapes varied dramatically. The Tigerholm et al. (2014) model best reproduced the experimental data, but these modeling efforts make clear that additional data are needed to parameterize and validate future models of autonomic C-fibers.NEW & NOTEWORTHY Peripheral nerves are primarily composed of unmyelinated axons, and there is growing interest in electrical stimulation of the autonomic nervous system to treat various diseases. We present the first cable model of an unmyelinated vagal nerve fiber and compare its ion channel isoforms and conduction responses with other published models of unmyelinated axons, establishing important tools for advancing modeling of autonomic nerves.

Nerve injury elevates functional Cav3.2 channels in superficial spinal dorsal horn

Cav3 channels play an important role in modulating chronic pain. However, less is known about the functional changes of Cav3 channels in superficial spinal dorsal horn in neuropathic pain states. Here, we examined the effect of partial sciatic nerve ligation (PSNL) on either expression or electrophysiological properties of Cav3 channels in superficial spinal dorsal horn. Our in vivo studies showed that the blockers of Cav3 channels robustly alleviated PSNL-induced mechanical allodynia and thermal hyperalgesia, which lasted at least 14 days following PSNL. Meanwhile, PSNL triggered an increase in both mRNA and protein levels of Cav3.2 but not Cav3.1 or Cav3.3 in rats. However, in Cav3.2 knockout mice, PSNL predominantly attenuated mechanical allodynia but not thermal hyperalgesia. In addition, the results of whole-cell patch-clamp recordings showed that both the overall proportion of Cav3 current-expressing neurons and the Cav3 current density in individual neurons were elevated in spinal lamina II neurons from PSNL rats, which could not be recapitulated in Cav3.2 knockout mice. Altogether, our findings reveal that the elevated functional Cav3.2 channels in superficial spinal dorsal horn may contribute to the mechanical allodynia in PSNL-induced neuropathic pain model.

Potential for endocannabinoid system modulation in ocular pain and inflammation: filling the gaps in current pharmacological options

Challenges in the management of ocular pain are an underappreciated topic. Currently available therapeutics lack both efficacy and clear guidelines for their use, with many also possessing unacceptable side effects. Promising novel agents would offer analgesic, anti-inflammatory, and possibly neuroprotective actions; have favorable ocular safety profiles; and show potential in managing neuropathic pain. Growing evidence supports a link between the endocannabinoid system (ECS) and a range of physiological and disease processes, notably those involving inflammation and pain. Both preclinical and clinical data suggest analgesic and anti-inflammatory actions of cannabinoids and ECS-modifying drugs in chronic pain conditions, including those of neuropathic origin. This review will examine existing evidence for the anatomical and physiological basis of ocular pain, specifically, ocular surface disease and the development of chronic ocular pain. The mechanism of action, efficacy, and limitations of currently available treatments will be discussed, and current knowledge related to ECS-modulation of ocular pain and inflammatory disease will be summarized. A perspective will be provided on the future directions of ECS research in terms of developing cannabinoid therapeutics for ocular pain.

Emerging neurotechnology for antinoceptive mechanisms and therapeutics discovery

The tolerance, abuse, and potential exacerbation associated with classical chronic pain medications such as opioids creates a need for alternative therapeutics. Phenotypic screening provides a complementary approach to traditional target-based drug discovery. Profiling cellular phenotypes enables quantification of physiologically relevant traits central to a disease pathology without prior identification of a specific drug target. For complex disorders such as chronic pain, which likely involves many molecular targets, this approach may identify novel treatments. Sensory neurons, termed nociceptors, are derived from dorsal root ganglia (DRG) and can undergo changes in membrane excitability during chronic pain. In this review, we describe phenotypic screening paradigms that make use of nociceptor electrophysiology. The purpose of this paper is to review the bioelectrical behavior of DRG neurons, signaling complexity in sensory neurons, various sensory neuron models, assays for bioelectrical behavior, and emerging efforts to leverage microfabrication and microfluidics for assay development. We discuss limitations and advantages of these various approaches and offer perspectives on opportunities for future development.

TRPs et al.: a molecular toolkit for thermosensory adaptations

The ability to sense temperature is crucial for the survival of an organism. Temperature influences all biological operations, from rates of metabolic reactions to protein folding, and broad behavioral functions, from feeding to breeding, and other seasonal activities. The evolution of specialized thermosensory adaptations has enabled animals to inhabit extreme temperature niches and to perform specific temperature-dependent behaviors. The function of sensory neurons depends on the participation of various types of ion channels. Each of the channels involved in neuronal excitability, whether through the generation of receptor potential, action potential, or the maintenance of the resting potential have temperature-dependent properties that can tune the neuron's response to temperature stimuli. Since the function of all proteins is affected by temperature, animals need adaptations not only for detecting different temperatures, but also for maintaining sensory ability at different temperatures. A full understanding of the molecular mechanism of thermosensation requires an investigation of all channel types at each step of thermosensory transduction. A fruitful avenue of investigation into how different molecules can contribute to the fine-tuning of temperature sensitivity is to study the specialized adaptations of various species. Given the diversity of molecular participants at each stage of sensory transduction, animals have a toolkit of channels at their disposal to adapt their thermosensitivity to their particular habitats or behavioral circumstances.

Slick (Kcnt2) Sodium-Activated Potassium Channels Limit Peptidergic Nociceptor Excitability and Hyperalgesia

The Slick (Kcnt2) sodium-activated potassium (K_Na) channel is a rapidly gating and weakly voltage-dependent and sodium-dependent potassium channel with no clearly defined physiological function. Within the dorsal root ganglia (DRGs), we show Slick channels are exclusively expressed in small-sized and medium-sized calcitonin gene–related peptide (CGRP)-containing DRG neurons, and a pool of channels are localized to large dense-core vesicles (LDCV)-containing CGRP. We stimulated DRG neurons for CGRP release and found Slick channels contained within CGRP-positive LDCV translocated to the neuronal membrane. Behavioral studies in Slick knockout (KO) mice indicated increased basal heat detection and exacerbated thermal hyperalgesia compared with wild-type littermate controls during neuropathic and chronic inflammatory pain. Electrophysiologic recordings of DRG neurons from Slick KO mice revealed that Slick channels contribute to outward current, propensity to fire action potentials (APs), and to AP properties. Our data suggest that Slick channels restrain the excitability of CGRP-containing neurons, diminishing pain behavior after inflammation and injury.

Pain in ankylosing spondylitis: a neuro-immune collaboration

Clinicians have commonly differentiated chronic back pain into two broad subsets: namely, non-inflammatory (or mechanical) back pain and inflammatory back pain. As the terminology suggests, the latter category, in which ankylosing spondylitis (AS) is prominent, presupposes a close link between pain and inflammation. Advances in research into the genetics and immunology of AS have improved our understanding of the inflammatory processes involved in this disease, and have led to the development of potent anti-inflammatory biologic therapeutic agents. However, evidence from clinical trials and from biomarker and imaging studies in patients with AS indicate that pain and inflammation are not always correlated. Thus, the assumption that pain in AS is a reliable surrogate marker for inflammation might be an over-simplification. This Review provides an overview of current concepts relating to neuro-immune interactions in AS and summarizes research that reveals an increasingly complex interplay between the activation of the immune system and pain pathways in the nervous system. The different types of pain experienced by patients with AS, insights from brain imaging studies, neurological mechanisms of pain, sex bias in pain and how the immune system can modify pain in patients with AS are also discussed.

An integrated perspective on diabetic, alcoholic, and drug-induced neuropathy, etiology, and treatment in the US

Neuropathic pain (NeuP) is a syndrome that results from damaged nerves and/or aberrant regeneration. Common etiologies of neuropathy include chronic illnesses and medication use. Chronic disorders, such as diabetes and alcoholism, can cause neuronal injury and consequently NeuP. Certain medications with antineoplastic effects also carry an exquisitely high risk for neuropathy. These culprits are a few of many that are fueling the NeuP epidemic, which currently affects 7%-10% of the population. It has been estimated that approximately 10% and 7% of US adults carry a diagnosis of diabetes and alcohol disorder, respectively. Despite its pervasiveness, many physicians are unfamiliar with adequate treatment of NeuP, partly due to the few reviews that are available that have integrated basic science and clinical practice. In light of the recent Centers for Disease Control and Prevention guidelines that advise against the routine use of μ-opioid receptor-selective opioids for chronic pain management, such a review is timely. Here, we provide a succinct overview of the etiology and treatment options of diabetic and alcohol- and drug-induced neuropathy, three different and prevalent neuropathies fusing the combined clinical and preclinical pharmacological expertise in NeuP of the authors. We discuss the anatomy of pain and pain transmission, with special attention to key ion channels, receptors, and neurotransmitters. An understanding of pain neurophysiology will lead to a better understanding of the rationale for the effectiveness of current treatment options, and may lead to better diagnostic tools to help distinguish types of neuropathy. We close with a discussion of ongoing research efforts to develop additional treatments for NeuP.