Neuropathic pain: diagnosis, pathophysiological mechanisms, and treatment. Lancet Neurol. 2010;9:807-819. [PMID: 20650402 DOI: 10.1016/s1474-4422(10)70143-5]

Default mode network-basal ganglia network connectivity predicts the transition to postherpetic neuralgia

Background

Neuroimaging studies have revealed aberrant network functional connectivity in postherpetic neuralgia (PHN) patients. However, there is a lack of knowledge regarding the relationship between the brain network connectivity during the acute period and disease prognosis.

Objective

The purpose of this study was to detect characteristic network connectivity in the process of herpes zoster (HZ) pain chronification and to identify whether abnormal network connectivity in the acute period can predict the outcome of patients with HZ.

Methods

In this cross-sectional study, 31 patients with PHN, 33 with recuperation from herpes zoster (RHZ), and 28 with acute herpes zoster (AHZ) were recruited and underwent resting-state functional magnetic resonance imaging (fMRI). We investigated the differences in the connectivity of four resting-state networks (RSN) among the three groups. Receiver operating characteristic (ROC) curve analysis was performed to identify whether abnormal network connectivity in the acute period could predict the outcome of patients with HZ.

Results

First, we found within-basal ganglia network (BGN) and default mode network (DMN)-BGN connectivity differences, with PHN patients showing increased DMN-BGN connectivity compared to AHZ and RHZ patients, while RHZ patients showing increased within-BGN connectivity compared to AHZ and PHN patients. Moreover, DMN-BGN connectivity was associated with the ID pain score in patients with AHZ. Finally, the DMN-BGN connectivity of AHZ patients could predict the outcome of HZ patients with sensitivity and specificity of 77.8 % and 63.2 %, respectively.

Conclusions

Our results provide evidence that DMN-BGN connectivity during the acute period confers a risk for the development of chronic pain and can act as a neuroimaging biomarker to predict the outcome of patients with HZ.

Combat-related peripheral nerve injuries

Active-duty service members (ADSM) and military Veterans represent a population with increased occupational risk for nerve injuries sustained both during training operations and wartime. Mechanisms of war-related nerve injuries have evolved over time, from the musket ball-related traumas described by S.W. Mitchell to complex blast injuries and toxic exposures sustained during Middle East conflicts in the 21st century. Commonly encountered nerve injury etiologies in this population currently include compression, direct trauma, nutritional deficits, traumatic limb amputation, toxic chemical exposures, or blast-related injuries. Expeditious identification and comprehensive, interdisciplinary treatment of combat-associated neuropathies, as well as prevention of these injuries whenever possible is critical to reduce chronic morbidity and disability for service members and to maintain a well-prepared military. However, diagnosis of a combat-associated nerve injury may be particularly challenging due to comorbid battlefield injuries or delayed presentation of neuropathy from military toxic exposures. Advances in imaging for nerve injury, including MRI and ultrasound, provide useful tools to compliment EMG in establishing a diagnosis of combat-associated nerve injury, particularly in the setting of anatomic disruption or edema. Surgical techniques can improve pain control or restoration of function. In all cases, comprehensive interdisciplinary rehabilitation provides the best framework for optimization of recovery. Further work is needed to prevent combat-associated nerve injuries and promote nerve recovery following injury.

Diabetic neuropathy: cutting-edge research and future directions

Diabetic neuropathy (DN) is a prevalent and debilitating complication of diabetes mellitus, significantly impacting patient quality of life and contributing to morbidity and mortality. Affecting approximately 50% of patients with diabetes, DN is predominantly characterized by distal symmetric polyneuropathy, leading to sensory loss, pain, and motor dysfunction, often resulting in diabetic foot ulcers and lower-limb amputations. The pathogenesis of DN is multifaceted, involving hyperglycemia, dyslipidemia, oxidative stress, mitochondrial dysfunction, and inflammation, which collectively damage peripheral nerves. Despite extensive research, disease-modifying treatments remain elusive, with current management primarily focusing on symptom control. This review explores the complex mechanisms underlying DN and highlights recent advances in diagnostic and therapeutic strategies. Emerging insights into the molecular and cellular pathways have unveiled potential targets for intervention, including neuroprotective agents, gene and stem cell therapies, and innovative pharmacological approaches. Additionally, novel diagnostic tools, such as corneal confocal microscopy and biomarker-based tests, have improved early detection and intervention. Lifestyle modifications and multidisciplinary care strategies can enhance patient outcomes. While significant progress has been made, further research is required to develop therapies that can effectively halt or reverse disease progression, ultimately improving the lives of individuals with DN. This review provides a comprehensive overview of current understanding and future directions in DN research and management.

Clinical Benefits of Ibuprofen Arginine: A Narrative Review

Ibuprofen arginine (IBA) combines well-established analgesic and anti-inflammatory properties with enhanced pharmacokinetics. The addition of arginine significantly improves solubility and absorption, leading to a faster onset of action compared to conventional ibuprofen. Clinical studies consistently demonstrate that IBA achieves meaningful pain relief within a shorter timeframe while maintaining a favorable safety profile. IBA's rapid action is particularly valuable in managing acute exacerbations of chronic pain and preventing central sensitization, thus improving patient comfort, adherence, and overall quality of life. By addressing both the inflammatory and nociceptive components of pain, IBA offers an effective and well-tolerated alternative in multimodal pain management strategies. This review explores the clinical benefits of IBA in pain management among various clinical settings.

Kilohertz High-Frequency Electrical Stimulation Effectively Mitigates Hyperalgesia in Mice With Neuropathic Pain Through Regulation of the Calcium/Calmodulin-Dependent Protein Kinase II/N-Methyl-D-Aspartate 2B Signaling Pathway

OBJECTIVES

Kilohertz high-frequency electrical stimulation (KHES), an avant-garde neuromodulation strategy, is progressively emerging in the field of neuropathic pain management, showing its unique therapeutic potential. This study delves into the mechanisms by which KHES exerts therapeutic effects on neuropathic pain induced by chronic constriction injury (CCI) in mice through modulation of the calcium/calmodulin-dependent protein kinase II (CaMKII)/N-methyl-D-aspartate receptor 2B (NMDAR2B) signaling pathway.

MATERIALS AND METHODS

In this study, mice were randomly assigned to groups and received intrathecal injections of CaMKII activator BayK8644, CaMKII inhibitor KN93, and N-methyl-D-aspartate (NMDA). Subsequently, mice underwent a week-long KHES treatment, with each session lasting 30 minutes. The impact of KHES on mechanical allodynia and thermal hyperalgesia in mice was assessed through paw withdrawal threshold and thermal withdrawal latency measurements, respectively. In addition, anxiety and depressive-like behaviors in mice were evaluated using pole climbing, open field, and forced swim tests. Quantitative reverse transcription polymerase chain reaction, Western blot, and immunofluorescence techniques were used to detect the expression levels of CaMKII, phosphorylated CaMKII (p-CaMKII), and NMDAR2B in the spinal cord.

RESULTS

Results indicated that KHES not only significantly reduced mechanical allodynia in CCI mice, with a sustained analgesic effect lasting up to six hours, but also somewhat alleviated anxiety and depressive-like symptoms. KHES inhibited the expression of p-CaMKII and NMDAR2B in the spinal cord. This inhibitory effect was reversed in the presence of BayK8644 and NMDA, suggesting that activation of CaMKII and NMDAR2B may contribute to the maintenance of neuropathic pain. Conversely, KN93 enhanced the analgesic effect of KHES by reducing mechanical allodynia and downregulating p-CaMKII and NMDAR2B expression, further confirming the significance of the CaMKII/NMDAR2B signaling pathway in KHES-mediated neuropathic pain relief.

CONCLUSION

This study not only unveils the potential therapeutic value of KHES in treating neuropathic pain induced by CCI in mice but also provides insights into its molecular mechanisms of action through inhibition of the CaMKII/NMDAR2B signaling pathway.

Anxa10 and neuropathic pain: Insights into dysregulation of endoplasmic reticulum-mitochondria contact tethering complex and therapeutic potential

The stability of membrane contact sites is critically dependent on Endoplasmic Reticulum mitochondria contact tethering complexes (EMCTCs), and dysregulation of these sites has been implicated in neuropathic diseases. In this study, we examined the role of Annexin A10 (Anxa10), a calcium-dependent protein, in neuropathic pain by investigating its influence on EMCTCs dysregulation. Using RNA sequencing, western blotting, and behavioral assays, we observed that spared nerve injury (SNI)-induced neuropathic pain significantly increased Anxa10 expression levels within the spinal dorsal horn (SDH) of mice. By employing cell-specific gene regulation via the Cre/loxp system, we utilized loxp-modified adeno-associated virus vectors to modulate Anxa10 expression in GAD2-Cre (inhibitory neurons), vGlut2-Cre (excitatory neurons), and Fos-Cre (activity-induced neurons) transgenic mice. Our results demonstrated that specific down-regulation of Anxa10 in excitatory neurons within the SDH alleviated neuropathic pain, whereas up-regulation of Anxa10, regardless of cell type, induced spontaneous pain in mice. Ultrastructural analysis of the endoplasmic reticulum (ER) and mitochondria, as well as double immunofluorescence staining, revealed that downregulation of Anxa10 mitigated the SNI-induced reduction in ER-mitochondrial distance. Additionally, it attenuated the SNI-induced upregulation of key components of EMCTCs, including IP3R, GRP75, and VDAC1, while preventing the SNI-induced downregulation of NCX3 expression. Furthermore, we formulated and validated the hypothesis that SGK1 and PI3K are positioned downstream of Anxa10. The up-regulation of Anxa10 compromised mitochondrial integrity and disrupted mitochondrial networks, ultimately leading to elevated oxidative stress. Collectively, these findings suggest that Anxa10 represents a promising therapeutic target for correcting EMCTCs dysregulation and mitigating neuropathic pain.

In situ piezoelectricity induces M2 polarization of macrophages to regulate Schwann cells for alleviating neuropathic pain of CCI rats

Peripheral nerve injuries often lead to neuropathic pain (NP), which is influenced by macrophage polarization, impacting Schwann cell function. Bioelectric signals, particularly from piezoelectric materials like polyvinylidene fluoride (PVDF), play a pivotal role in modulating macrophage polarization. In this study, we demonstrate that PVDF's piezoelectric properties enhance M2 polarization during hypoxia macrophage model, as indicated by increased CD206 (M2 marker) expression and decreased CD8 (M1 marker). This shift in polarization is linked to enhanced secretion of Arg-1 and IL-10 from M2 macrophages, and reduced levels of ROS, iNOS, and TNF-α from M1 macrophages. The underlying mechanism driving this polarization shift involves the activation of the AMPK signaling pathway. In vitro, M2-conditioned medium significantly promoted Schwann cell proliferation and migration. In a chronic sciatic nerve constriction (CCI) rat model, PVDF treatment improved pain sensitivity, as shown by increased mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). Additionally, PVDF treatment reduced the CD80/CD206 (M1/M2) ratio, promoting an anti-inflammatory environment, and increased the NF200/S100 ratio, indicating enhanced axonal regeneration. RNA sequencing revealed that Schwann cells co-cultured with M2-conditioned medium upregulated Cell Adhesion Molecule (CAM), Ca+ signaling pathway, and Mitogen Activated Protein Kinases (MAPK), critical signal pathway for Schwann cell regeneration and nerve repair. Our findings suggest that PVDF's piezoelectric properties offer a novel strategy for modulating macrophage polarization and enhancing Schwann cell activity, providing a potential therapeutic approach for NP.

Protein Kinases as Mediators for miRNA Modulation of Neuropathic Pain

Neuropathic pain is a chronic condition resulting from injury or dysfunction in the somatosensory nervous system, which leads to persistent pain and a significant impairment of quality of life. Research has highlighted the complex molecular mechanisms that underlie neuropathic pain and has begun to delineate the roles of microRNAs (miRNAs) in modulating pain pathways. miRNAs, which are small non-coding RNAs that regulate gene expression post-transcriptionally, have been shown to influence key cellular processes, including neuroinflammation, neuronal excitability, and synaptic plasticity. These processes contribute to the persistence of neuropathic pain, and miRNAs have emerged as critical regulators of pain behaviors by modulating signaling pathways that control pain sensitivity. miRNAs can influence neuropathic pain by targeting genes that encode protein kinases involved in pain signaling. This review focuses on miRNAs that have been demonstrated to modulate neuropathic pain behavior through their effects on protein kinases or their immediate upstream regulators. The relationship between miRNAs and neuropathic pain behaviors is characterized as either an upregulation or a downregulation of miRNA levels that leads to a reduction in neuropathic pain. In the case of miRNA upregulation resulting in an alleviation of neuropathic pain behaviors, protein kinases exhibit a positive correlation with neuropathic pain, whereas decreased protein kinase levels correlate with diminished neuropathic pain behaviors. The only exception is GRK2, which shows an inverse correlation with neuropathic pain. In the case of miRNA downregulation resulting in a reduction in neuropathic pain behaviors, protein kinases display mixed relationships to neuropathic pain, with some kinases exhibiting positive correlation, while others exhibit negative correlation. By exploring how protein kinases mediate miRNA modulation of neuropathic pain, valuable insight may be gained into the pathophysiology of neuropathic pain, offering potential therapeutic targets for developing more effective strategies for pain management.

The use of TENS for the treatment of back pain in the emergency department: A randomized controlled trial

OBJECTIVE

Back pain is one of the most common complaints in the emergency department (ED). Since current pharmacological treatments for back pain are often suboptimal, a multimodal approach that includes nonpharmacological modalities has promise to improve pain management. The objective of the current study was to test the hypothesis that transcutaneous electrical nerve stimulation (TENS) would be more effective at relieving back pain than sham TENS.

METHODS

We conducted a patient- and observer-blinded, randomized controlled trial that included adult (≥18 years) ED patients with lumbar or thoracic back pain of at least moderate pain severity. Participants were randomly assigned (1:1) to TENS or sham TENS. The primary outcome was absolute reduction in pain severity at 30 min after treatment measured with a verbal numeric scale from 0 to 10 (none to worst). A sample of 80 patients had 80% power to detect a 1.5-point between-group difference in pain severity. The trial was registered with ClinicalTrials.gov (NCT04227067).

RESULTS

We enrolled 80 subjects (40 to the TENS group, 40 to the sham group). Mean (±SD) age was 46 (±16) years, and 51% were female. Mean (±SD) pain scores before and after treatment were 8.4 (±1.6) and 6.8 (±2.4) in patients treated with TENS. Mean (±SD) pain scores before and after treatment were 8.0 (±1.7) and 7.5 (±2.1) in patients treated with sham TENS. The mean (±SD) reduction in pain score was significantly greater in TENS versus sham patients, 1.7 (±2.0) versus 0.5 (±1.0; p = 0.002). Rescue medication was administered to fewer patients treated with TENS than with sham (45% vs. 73%, p = 0.02) and patient satisfaction was higher in the TENS than in the sham group (78% vs. 50%, p = 0.02).

CONCLUSIONS

TENS was more effective than sham TENS at reducing pain severity in adult ED patients with back pain.

Ending neck pain: the impact of anterior cervical discectomy and fusion in cervical radiculopathy

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) is a well-established surgical intervention for cervical radiculopathy, primarily indicated to relieve radicular symptoms. While some studies suggest that ACDF improves neck pain, historical data report inconsistent results. This study aimed to evaluate the impact of ACDF on neck pain in patients with isolated cervical radiculopathy treated at a high-volume tertiary care center.

METHODS

A retrospective review of all ACDF procedures performed at Leeds General Infirmary between January 2021 and March 2023 was conducted. Inclusion criteria were patients undergoing ACDF for isolated cervical radiculopathy. Exclusion criteria included procedures performed for other indications, including myelopathy, myeloradiculopathy, trauma, or tumors. VAS (Visual Analogue Scale) scores for neck pain were collected at four time points: preoperatively, 3 months, 6 months, and 12 months postoperatively. Statistical analysis included mean score comparisons and binomial distribution testing at a 1 % significance level. A total of 41 patients with complete data were included in the final analysis.

RESULTS

The mean preoperative VAS score was 8.32, indicating severe pain (VAS > 7.5). The reduction in neck pain following ACDF exceeded the minimum clinically important difference (MCID) of 2.6 at all postoperative time points, with mean improvements of 3.24 ± 1.76 (39.1 % pain reduction, t(40) = 11.8, p < 0.001), 3.61 ± 1.90 (43.4 % pain reduction, t(40) = 12.2, p < 0.001), and 3.83 ± 2.11 (46.0 % pain reduction, t(40) = 12.2, p < 0.001) at 3, 6, and 12 months, respectively. The proportion of patients reporting severe neck pain decreased significantly from 78.0 % preoperatively to 14.6 % postoperatively (p < 0.01).

CONCLUSIONS

ACDF significantly reduces neck pain in patients with cervical radiculopathy, with the most substantial improvement observed within the first three months postoperatively. Pain reduction remained stable and clinically meaningful for up to 12 months. These findings support the efficacy of ACDF in addressing radiculopathy and associated neck pain. Future prospective studies incorporating additional outcome measures, such as quality of life and mental health, are warranted to provide a more comprehensive assessment of patient benefits.

Electrical Nerve Stimulation Induces Synaptic Plasticity in the Brain and the Spinal Cord: A Systematic Review

OBJECTIVES

This review aimed to compile the literature on synaptic plasticity induced by electrical nerve stimulation (ENS) in nociceptive and somatosensory circuits within the central nervous system, with a particular focus on its effects on both the brain and spinal cord. Understanding the mechanisms underlying synaptic changes, enhances our comprehension of how ENS contributes to both pain relief and the development of experimental pain models.

MATERIALS AND METHODS

We conducted a systematic search of PubMed, Scopus, PEDro, SciELO, and Cochrane databases, adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, and evaluated the quality of evidence using SYRCLE's risk of bias tool. The inclusion criteria were application of ENS to peripheral nerves, reporting of a detailed methodology, providing direct physiological measurements of synaptic activity (eg, field potentials or intracellular recordings), and publication in English or Spanish. From 8094 results, 85 studies met the inclusion criteria.

RESULTS

ENS was found to induce synaptic potentiation in 70 studies, depression in 7, and both effects in 8. These outcomes were determined by specific stimulation parameters and individual characteristics, with distinct molecular mechanisms involved in each case. Notably, most research focused on long-term potentiation in nociceptive pathways to create experimental pain models, with most studies conducted in the spinal cord. Few studies explored the link between ENS-induced synaptic plasticity and its analgesic effects or the role of plasticity in supraspinal brain regions, suggesting promising areas for future research.

CONCLUSIONS

ENS-induced synaptic plasticity presents a valuable opportunity for both pain management and the development of experimental pain models. Further research is needed to explore the connections between plasticity, analgesia, and higher brain regions.

( +)-Catechin Alleviates CCI-Induced Neuropathic Pain by Modulating Microglia M1 and M2 Polarization via the TLR4/MyD88/NF-κB Signaling Pathway

The aim of this research endeavor was to explore the therapeutic potential of ( +)-catechin in mitigating neuropathic pain. A total of thirty-two Sprague‒Dawley rats were randomly allocated into four groups: the sham group, the chronic constriction injury (CCI) group, the CCI + ibuprofen group, and the CCI + ( +)-catechin group. The results of the in vivo experiment show that ( +)-catechin has the potential to improve mechanical hyperalgesia induced by CCI and reduce the infiltration of inflammatory cells in the injured sciatic nerve. CCI induces the upregulation of nNOS, iNOS, IL-1β, and COX-2 within the rat sciatic nerve and leads to an elevation in the levels of IL-1β, PGE2, and TNF-α in the serum of rats, while simultaneously diminishing the secretion of IL-10. Moreover, immunofluorescence analysis reveals that CCI enhances the expression of CD32 (an M1 polarization marker) in the rat spinal cord, while diminishing the expression of CD206 (an M2 polarization marker). However, the administration of ( +)-catechin effectively counteracts these effects. Western blot analysis further demonstrates that ( +)-catechin significantly reduces the protein expression of IBA-1, IL-1β, MyD88, p-NF-κB, p-JNK, p-ERK, p-p38MAPK, COX-2, and TLR4 within the spinal cord. The findings of the BV2 cell experiment revealed the attenuating effects of ( +)-catechin on M1 polarization markers (such as IL-1β, TNF-α, iNOS, and CD32), while concurrently boosting the levels of M2 polarization markers (including CD206, IL-10, and Arg-1). Notably, administration of LPS significantly heightened the accumulation of IBA-1, IL-1β, MyD88, p-NF-κB, p-JNK, p-ERK, p-p38MAPK, TLR4, COX-2, and iNOS, while concurrently suppressing Arg-1 expression. However, the administration of ( +)-catechin effectively reversed these alterations. Overall, these findings suggest that ( +)-catechin alleviates neuropathic pain by modulating the M1 and M2 phenotypes of microglia through the TLR4/MyD88/NF-κB pathway.

Bidirectional Modulation of Somatostatin-expressing Interneurons in the Basolateral Amygdala Reduces Neuropathic Pain Perception in Mice

Neuropathic pain is characterized by mechanical allodynia and thermal (heat and cold) hypersensitivity, yet the underlying neural mechanisms remain poorly understood. This study examines the role of inhibitory interneurons in the basolateral amygdala (BLA) in modulating pain perception following nerve injury. Chemogenetic excitation of parvalbumin-positive (PV + ) interneurons significantly alleviated mechanical allodynia but had minimal effects on thermal hypersensitivity. However, inhibition of PV + interneurons did not produce significant changes in pain sensitivity, suggesting that reductions in perisomatic inhibition do not contribute to chronic pain states. In contrast, bidirectional modulation of somatostatin-positive (SST + ) interneurons influenced pain perception in a modality-specific manner. Both excitation and inhibition of SST + interneurons alleviated mechanical allodynia, indicating a potential compensatory role in nociceptive processing. Additionally, SST + neuron excitation reduced cold hypersensitivity without affecting heat hypersensitivity, whereas inhibition improved heat hypersensitivity but not cold responses. These findings suggest that, in addition to PV + neurons, SST + interneurons in the BLA play a complex role in modulating neuropathic pain following nerve injury and may serve as a potential target for future neuromodulation interventions in chronic pain management.

Epidermal Transient Receptor Potential Vanilloid 1 innervation is increased in patients with painful diabetic polyneuropathy experiencing ongoing burning pain

ABSTRACT

Preclinical studies suggested that Transient Receptor Potential Vanilloid 1 (TRPV1) channels contribute to neuropathic pain in animal models of diabetic polyneuropathy. Patients with painful diabetic polyneuropathy commonly experience ongoing burning pain. This study aimed at evaluating the association between this specific type of pain and TRPV1 intraepidermal nerve fibers in patients with painful diabetic polyneuropathy. We consecutively enrolled 70 patients with diabetic polyneuropathy. Each patient completed the Neuropathic Pain Symptom Inventory (NPSI) to identify the various types of neuropathic pain. All patients underwent a distal leg skin biopsy, with immunostaining of skin nerve fibers using antibodies for the pan-axonal marker Protein Gene Product 9.5 (PGP9.5), TRPV1, Calcitonin Gene-Related Peptide (CGRP), and Substance P. We found that 57% of patients (n = 40) had neuropathic pain symptoms, with ongoing burning pain being the most frequently reported type of pain at the NPSI (70% of patients with pain, n = 28). Patients with ongoing burning pain had higher TRPV1 intraepidermal nerve fiber density and TRPV1/PGP9.5 ratio compared with those with painless polyneuropathy ( P = 0.014, P = 0.013) and painful polyneuropathy with other types of pain ( P < 0.0001, P = 0.024); they also had increased CGRP dermal nerve fiber density compared with patients with painless polyneuropathy ( P = 0.005). Our study showed that ongoing burning pain is associated with an increased expression of intraepidermal TRPV1 fibers, as well as an increased dermal representation of CGRP fibers. These findings suggest that TRPV1 contributes to ongoing burning pain, possibly in conjunction with elevated CGRP expression, highlighting its significance as a therapeutic target for patients with painful diabetic polyneuropathy.

Mechanisms and Therapeutic Prospects of Microglia-Astrocyte Interactions in Neuropathic Pain Following Spinal Cord Injury

Neuropathic pain is a prevalent and debilitating condition experienced by the majority of individuals with spinal cord injury (SCI). The complex pathophysiology of neuropathic pain, involving continuous activation of microglia and astrocytes, reactive gliosis, and altered neuronal plasticity, poses significant challenges for effective treatment. This review focuses on the pivotal roles of microglia and astrocytes, the two major glial cell types in the central nervous system, in the development and maintenance of neuropathic pain after SCI. We highlight the extensive bidirectional interactions between these cells, mediated by the release of inflammatory mediators, neurotransmitters, and neurotrophic factors, which contribute to the amplification of pain signaling. Understanding the microglia-astrocyte crosstalk and its impact on neuronal function is crucial for developing novel therapeutic strategies targeting neuropathic pain. In addition, this review discusses the fundamental biology, post-injury pain roles, and therapeutic prospects of microglia and astrocytes in neuropathic pain after SCI and elucidates the specific signaling pathways involved. We also speculated that the extracellular matrix (ECM) can affect the glial cells as well. Furthermore, we also mentioned potential targeted therapies, challenges, and progress in clinical trials, as well as new biomarkers and therapeutic targets. Finally, other relevant cell interactions in neuropathic pain and the role of glial cells in other neuropathic pain conditions have been discussed. This review serves as a comprehensive resource for further investigations into the microglia-astrocyte interaction and the detailed mechanisms of neuropathic pain after SCI, with the aim of improving therapeutic efficacy.

New generation capsaicin-diclofenac containing, silicon-based transdermal patch provides prolonged analgesic effect in acute and chronic pain models

OBJECTIVE

Pain is one of the major public health burdens worldwide, however, conventional analgesics are often ineffective. Capsaicin-the active compound of Capsicum species, being responsible for their pungency-has been part of traditional medicine long ago. Capsaicin is a natural agonist of the Transient Receptor Potential Vanilloid 1 receptor-localized on capsaicin-sensitive sensory neurons and strongly involved in pain transmission-, and has been in focus of analgesic drug research for many years. In this study, we aimed to develop a sustained release transdermal patch (transdermal therapeutic system, TTS) combining the advantages of low-concentration capsaicin and diclofenac embedded in an innovative structure, as well as to perform complex preclinical investigations of its analgesic effect.

METHODS

Drug delivery properties of the TTS were investigated with Franz cell and flow-through cell tests. Analgesic effect of the TTS was examined in in vivo models of acute postoperative and inflammatory, chronic neuropathic and osteoarthritic pain.

RESULTS

Modified silicone polymer matrix-based TTS containing low-concentration capsaicin and diclofenac has been developed, releasing both compounds according to zero-order kinetics. Moreover, capsaicin and diclofenac facilitated the liberation of each other. Combined TTS significantly reduced acute postoperative and inflammatory pain, as well as chronic neuropathic and osteoarthritic pain. Interestingly, in acute postoperative and chronic osteoarthritic pain, capsaicin prolonged and potentiated the pain-relieving effect of diclofenac.

CONCLUSIONS

New generation combined low-concentration capsaicin-diclofenac containing TTS can be an effective therapeutic tool in acute and chronic pain states involving neuropathic and inflammatory components.

Resolvin D1 accelerates resolution of neuroinflammation by inhibiting microglia activation through the BDNF/TrkB signaling pathway

BACKGROUND

Neuropathic pain is characterized by hyperalgesia, allodynia, and inflammation and it is often resistant to treatment. The formyl peptide receptor 2 (ALX/FPR2), a G-protein-coupled receptor, has been implicated in resolving inflammation, making its agonist, Resolvin D1 (RvD1), a potential therapeutic agent. Previous studies suggest that RvD1 alleviates neuropathic pain via anti-inflammatory effects, but its mechanisms remain unclear, particularly in relation to microglial activation and the brain-derived neurotrophic factor (BDNF)/TrkB signaling pathway.

OBJECTIVE

To investigate the analgesic effects of RvD1 in a spared nerve injury (SNI) model of neuropathic pain and explore its mechanisms through the regulation of neuroinflammation and the BDNF/TrkB signaling pathway.

METHODS

SNI mice received intrathecal RvD1 at varying doses (10-40 ng) to determine its efficacy in reducing mechanical allodynia and thermal sensitivity. The anti-inflammatory effects of RvD1 were assessed using ELISA, immunofluorescence, and western blotting to measure the expression of pro-inflammatory cytokines and BDNF. The involvement of ALX/FPR2 and TrkB receptors was further examined using antagonists Boc2 and K252a.

RESULTS

RvD1 significantly reduced mechanical and thermal allodynia in SNI mice in a dose-dependent manner. RvD1 also decreased microglial activation and expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and BDNF in both in vivo and in vitro models. These effects were reversed by Boc2 and K252a, confirming that the analgesic actions of RvD1 are mediated via the ALX/FPR2 receptor and inhibition of BDNF/TrkB signaling.

CONCLUSION

RvD1 alleviates neuropathic pain by reducing neuroinflammation through the ALX/FPR2 receptor and suppressing BDNF/TrkB signaling. These findings suggest RvD1 as a promising therapeutic agent for neuropathic pain management.

The silence of opioids-dependent chronic pain patients: A text mining analysis from sex and gender perspective

Existing evidence indicates sex-related differences in Prescription Opioid Use Disorder (OUD) in Chronic Non-Cancer Pain (CNCP). However to date, there is scant evidence for other socioeconomic factors in these differences. Our aim was to enquire about the influence of gender and drug copayment of OUD narratives by the text mining analysis. A prospective mixed-methods study was designed and performed at Pain Unit (PU) including 238 real world patients with CNCP divided in controls (n = 206) and OUD cases (n = 32) due to DSM-5 diagnosis Variables related to pain, sleep, mental and health status were collected in together with sex and gender interaction, in pain status, along 30-45 min face-to-face interviews. Sex differences were observed due to women's significantly older ages, with a stronger impact on mental health, and an even stronger one for the OUD women. Globally, OUD cases were more unemployed vs the CNCP controls, and on a significantly higher median opioid daily dose of 90 [100] mg/day. Although OUD participants did more social activities, they tended to use less vocabulary to express themselves regardless of their sex, gender role or economic status. In contrast, the CNCP participants presented more differences driven by their incomes, with "limited" being the most discriminating word for those on low income, followed by "less" and "help". Here, the most significant word of CNCP women was "husband", followed by "tasks". In contrast, gender reproductive roles shared similarities in both sexes, being one of the most discriminatory words "help". The data show that OUD patients seem to have a marked influence of OUD on poorer lexicon and simpler narrative, together with a significant impact of socioeconomic factors on the CNCP narratives. The conclusion suggests to extend the research to better understand the effect of sex, gender and socioeconomic status in CNCP especially on OUD women's health.

Using Integrated Network Pharmacology and Metabolomics to Reveal the Mechanisms of the Combined Intervention of Ligustrazine and Sinomenine in CCI-Induced Neuropathic Pain Rats

Neuropathic pain (NP) is a type of chronic pain resulting from injury or dysfunction of the nerves or spinal cord. Previous studies have shown that the combination of ligustrazine (LGZ) and sinomenine (SIN) exerts a synergistic antinociceptive effect in peripheral and central NP models. On this basis, a comprehensive analgesic evaluation was performed in a chronic constriction injury (CCI)-induced NP model in rats. Sciatic nerve histopathological changes were observed, and 22 cytokines and chemokines levels were analyzed. We also combined network pharmacology and metabolomics to explore their molecular mechanisms. Results showed that the combination of LGZ and SIN significantly alleviated the pain-like behaviors in CCI rats in a time- and dose-dependent manner, demonstrating superior therapeutic effects compared to LGZ or SIN alone. It also improved pathological damage to sciatic nerves and regulated inflammatory cytokine levels. Network pharmacology identified shared and distinct pain-related targets for LGZ and SIN, while metabolomics revealed 54 differential metabolites in plasma, and 17 differential metabolites in CSF were associated with the combined intervention of LGZ and SIN. Finally, through an integrated analysis of the core targets and differential metabolites, tyrosine metabolism, phenylalanine metabolism, and arginine and proline metabolism were identified as potential key metabolic pathways underlying the therapeutic effects of LGZ and SIN in CCI treatment. In conclusion, our study provides evidence to support the clinical application of LGZ and SIN in the treatment of NP.

Genetic Evidence Indicates that Serum Micronutrient Levels Mediate the Causal Relationships Between Immune Cells and Neuropathic Pain: A Mediation Mendelian Randomization Study

A growing body of evidence suggests a correlation among immune cells, serum micronutrient levels, and neuropathic pain. However, previous studies have been limited in scope, hindering the establishment of conclusive findings. Therefore, this study employs mendelian randomization (MR) analysis to investigate the genetic perspectives on the causal relationships among these factors. Initially, the relationship between five serum micronutrient levels (specifically, four vitamin levels and zinc levels) and neuropathic pain was examined using a bidirectional MR design. Subsequently, positive results identified through the inverse variance weighted (IVW) method prompted further analysis, using immune cells as exposures to explore their causal links with neuropathic pain. As a result, a two-step MR analysis demonstrated that serum vitamin levels mediate the relationship between immune cells and neuropathic pain, quantifying both direct impacts and mediation effects. This study revealed that low serum levels of vitamin D and 25-hydroxyvitamin D increased the risk of postherpetic neuralgia and thoracic spine pain. Reverse MR analysis suggested that neuropathic pain does not contribute to a reduction in the serum levels of vitamin D and 25-hydroxyvitamin D. Furthermore, significant associations were observed between 27 immune cells and postherpetic neuralgia, as well as between 22 immune cells and thoracic spine pain. Additionally, the mediation analysis identified causal relationships between immune cells and serum micronutrient levels, confirming the "immune cells-serum micronutrient levels-neuropathic pain" pathway. This study provides valuable insights into the potential mechanisms by which vitamin D and 25-hydroxyvitamin D regulate the interaction between the immune system and neuropathic pain. These findings are crucial for the timely detection, treatment, and management of neuropathic pain, offering new perspectives on how vitamin levels influence immune cell behavior and neuropathic pain susceptibility.

Predictors for quality of life improvement following rTMS treatment in neuropathic pain patients

OBJECTIVES

Recently, Repetitive Transcranial Magnetic Stimulation (rTMS) has gained attention for its potential in relieving neuropathic pain (NP). NP encompasses central and peripheral neuralgia, characterized by sensory abnormalities and spontaneous pain. Pharmacological treatments often provide partial relief with significant side effects, making rTMS an attractive alternative. This study aimed to assess the efficacy of rTMS in treating NP and its impact on quality of life over three months.

METHODS

A total of 51 patients with drug-resistant NP were included, undergoing 15 sessions of rTMS targeting motor cortex areas over three weeks. Clinical response was evaluated using various psychometric scales, including VAS for pain and PGIC. Quality of life was assessed using the SF-36 questionnaire.

RESULTS

Results showed significant clinical improvements in pain severity and quality of life following rTMS treatment. Predictive factors of quality of life improvement were identified, with mental health being crucial across all NP areas. Notably, patients with cerebral NP showed improvements linked to physical dimensions, emphasizing tailored treatment approaches.

CONCLUSIONS

This study underscores the efficacy of rTMS in managing NP, highlighting sustained improvements in pain severity and quality of life. The findings offer valuable insights for personalized treatment approaches and optimizing patient outcomes in NP management.

Comparison of intermittent theta burst stimulation and high-frequency repetitive transcranial magnetic stimulation on spinal cord injury-related neuropathic pain: A sham-controlled study

OBJECTIVE

To compare the effects of intermittent theta burst stimulation (iTBS) and high-frequency repetitive transcranial magnetic stimulation (rTMS) on spinal cord injury-related neuropathic pain with sham controls, using neuropathic pain-specific evaluation tools.

DESIGN

A randomized, double-blind, sham-controlled trial.

SETTING

Rehabilitation medicine department of a university hospital.

PARTICIPANTS

Thirty-three patients with spinal cord injury-related neuropathic pain.

INTERVENTIONS

Patients were randomly allocated to one of three groups (real iTBS, real rTMS, and sham rTMS). Each patient underwent five sessions of assigned stimulation.

OUTCOME MEASURES

Before and after completion of the five sessions, patients were evaluated using the self-completed Leeds Assessment of Neuropathic Symptoms and Signs, Numeric Rating Scale, Neuropathic Pain Symptom Inventory, and Neuropathic Pain Scale.

RESULTS

Real iTBS and real rTMS reduced pain levels after stimulation according to all the evaluation tools, and the changes were significant when compared to the values of the sham rTMS group. No significant differences were found between the real iTBS and real rTMS groups.

CONCLUSION

Both iTBS and rTMS were effective in reducing spinal cord injury-related neuropathic pain. When safety, convenience, and compliance are considered, iTBS would have an advantage over rTMS in clinical situations with spinal cord injury-related neuropathic pain.Trial Registration: This trial was registered with the Clinical Research Information Service (registration no. KCT0004976).

Understanding the Pain Experience and Treatment Considerations Along the Spectrum of Peripheral Artery Disease: A Scientific Statement From the American Heart Association

Peripheral artery disease (PAD) is an atherosclerotic condition that affects a growing number of individuals worldwide, with estimates exceeding 220 million. One of the central hallmarks of PAD is lower extremity pain, which may present as intermittent claudication and atypical leg pain, and, in more severe cases, ischemic rest pain, neuropathic pain, or phantom limb pain in those who underwent amputation. Although the majority of individuals with PAD may experience pain that is chronic in nature, the pathogenesis and phenomenology of pain may differ. Nociceptive, inflammatory, and neuropathic mechanisms all play a role in the generation of pain. Pain in PAD results in severe disability and can copresent with distress, sickness behaviors such as avoidance and further deconditioning, and concomitant depression, anxiety, and addiction secondary to opioid use. These factors potentially lead to chronic pain interacting with a multitude of domains of functioning, including physical, emotional, and behavioral. Whereas pain is a normal adaptive response, self-defeating behaviors and cognitions contribute to the persistence or worsening of the chronic pain experience, disability, and distress. Much remains unknown about the phenomenology of pain in PAD and its clinical subgroups and how it affects outcomes. Borrowing from other chronic pain syndromes, multimodal pain management strategies that emphasize a biopsychosocial model have generated a solid evidence base for the use of cognitive behavioral approaches to manage pain. Multimodal pain management in PAD is not the norm, but theoretical pathways and road maps for further research, assessment, and clinical implementation are presented in this scientific statement.

Decoding the mechanism of proanthocyanidins in central analgesia: redox regulation and KCNK3 blockade

Neuropathic pain causes enduring physical discomfort and emotional distress. Conventional pharmacological treatments often provide restricted relief and may result in undesirable side effects, posing a substantial clinical challenge. Peripheral and spinal redox homeostasis plays an important role in pain processing and perception. However, the roles of oxidative stress and antioxidants in pain and analgesia on the cortical region during chronic pain remains obscure. Here we focus on the ventrolateral orbital cortex (VLO), a brain region associated with pain severity and involved in pain inhibition. Using a spared nerve injury mouse model, we observed the notable reactive oxygen species (ROS)-mediated suppression of the excitability of pyramidal cells (PYRVLO) in the VLO. Nasal application or microinjection of the natural antioxidants proanthocyanidins (PACs) to the VLO specifically increased the activity of PYRVLO and induced a significant analgesic effect. Mechanistically, PACs activate PYRVLO by inhibiting distinct potassium channels in different ways: (1) by scavenging ROS to reduce ROS-sensitive voltage-gated potassium currents and (2) by acting as a channel blocker through direct binding to the cap structure of KCNK3 to inhibit the leak potassium current (Ileak). These results reveal the role of cortical oxidative stress in central hyperalgesia and elucidate the mechanism and potential translational significance of PACs in central analgesia. These findings suggest that the effects of PACs extend beyond their commonly assumed antioxidant or anti-inflammatory effects.

Prevalence and risk factors for the development of chronic postoperative pain after cataract surgery in the Age-related Eye Disease Study (AREDS)

Chronic ocular pain impacts quality of life and is often linked to ocular surgery. We assessed the prevalence of chronic postoperative pain (CPOP) after cataract surgery and associated risk factors using a secondary cohort post-hoc analysis of data from the Age-Related Eye Disease Study (AREDS), a multicenter, controlled, randomized clinical trial of antioxidant vitamins and minerals. Ocular pain was determined from item 4 of the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25), administered between 1997 and 2005. We included participants who underwent cataract surgery during the study and reported no or mild ocular pain before first-eye cataract surgery (n=325). Controls (n=283) reported no or mild ocular pain 3 or more months after first-eye cataract surgery; cases (n=42) reported moderate or severe pain 3 or more months after first-eye cataract surgery. Multivariable logistic regression models assessed associations between potential risk factors (age, sex, body mass index, smoking, diabetes, education level, use of anti-inflammatory agents, use of antacids, general health, AREDS treatment group) and CPOP. Of the 325 participants (mean age, 69.7±4.4 years, 59.4 % female); CPOP developed in 42 (13 %; 95 % CI, 9.3 - 16.6 %). The average time between cataract surgery and the post-surgery VFQ was 18.4±11.8 months (range 3.0 - 65.0 months). Multivariable analysis did not reveal any statistically significant associations with odds of developing CPOP after cataract surgery. As such, in this AREDS cohort who underwent cataract surgery, 13% developed CPOP, consistent with previous reports from cataract and refractive surgery. Our post-hoc analyses did not identify any significant risk factors for CPOP. PERSPECTIVE: We found a high prevalence of Chronic Postoperative Pain (CPOP) in the AREDS cohort, with 13 % of participants who underwent cataract surgery developing CPOP. Post-hoc analysis did not identify significant risk factors for CPOP. Our study contributes valuable insights into a growing area of interest in pain management within ophthalmology.

[Systematic review of the effectiveness of local anaesthetics in the treatment of neuropathic pain or phantom pain]

BACKGROUND

Chronic pain is still a relevant medical and socioeconomic problem. The treatment focuses not only on pain reduction but also on functional treatment goals. Neuropathic pain includes biological, social and psychological aspects. In September 2023, the updated S3 guidelines for the management of peripheral nerve injuries were published. Multimodal pain management strategies encompassing systemic and local pharmacological, physiotherapeutic and occupational therapeutic interventions, are part of the guidelines. A central question addressed the widely debated treatment option using perineural local anaesthetics.

OBJECTIVE

The aim of the study was to evaluate the effectiveness of local anaesthetic infiltration in the treatment of neuropathic pain following nerve injuries through a systematic literature review and evaluation of the evidence by a meta-analysis.

MATERIAL AND METHODS

After formulating a PICO (patient/population, intervention, comparison and outcomes) question (Infobox 1) within the guideline group, a selective literature analysis of controlled trials in databases (PubMed, Cochrane Central Register of Controlled Trials-CENTRAL) was conducted until 31 July 2023. The literature was assessed by two reviewers and systematic reviews were examined for additional references. The studies were assessed using the Risk of Bias Tool 2.0 of the Cochrane Collaboration for randomized trials and the evidence was classified according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

RESULTS

A total of 357 publications were identified in the literature search. After removing duplicates (n = 15) 327 publications were evaluated. The literature analysis showed heterogeneity with respect to the pain localization, local anaesthetics and reported outcomes. In an in-depth literature analysis one relevant study was identified and included in the evaluation of the evidence. This study enrolled and randomized 144 patients between December 2013 and October 2018 and evaluated the effectivity of the continuous infusion of local anaesthetics (lidocaine 2% with epinephrine 2.5 µg/ml as an initial bolus in both study groups followed by an infusion of ropivacaine 0.5% in the intervention group over 6 days) on the intensity of the phantom pain in comparison to the placebo group with a continuous infusion of saline over 6 days. The mean pain intensity and pain-related dysfunctions were reduced in the intervention group after 4 weeks. In the intervention group 25 patients and in the placebo group 40 patients received the crossover treatment after 4 weeks.

CONCLUSION

Infiltration with local anaesthetics represents a potential therapeutic option for neuropathic pain and phantom pain after amputations. A randomized, blinded, placebo-controlled study from 2021 demonstrated lower pain intensity and a reduction in pain-related functional limitations after 4 weeks of continuous perineural local anesthetic infiltration. Further studies are necessary to establish a higher level of evidence regarding the effectiveness of minimally invasive pain treatment with local anaesthetics. In particular, long-term follow-up is necessary to be able to draw conclusions with respect to the analgesic efficacy of infiltration with local anaesthetics.

Association of Nerve Conduction Study Variables with Hematologic Tests in Patients with Type 2 Diabetes Mellitus

Background and Objective: Diabetic peripheral neuropathy (DPN) is a prevalent complication of type 2 diabetes mellitus (T2DM), with nerve conduction studies (NCSs) serving as the diagnostic gold standard. Early diagnosis is critical for effective management, yet many cases are detected late due to the gradual onset of symptoms. This study explores the relationship between hematological tests and NCS outcomes in T2DM patients to improve the early detection of DPN. Material and Methods: This retrospective study involved T2DM patients exhibiting neuropathic symptoms, and patients were divided based on NCS findings into groups with normal and abnormal results to assess the diagnostic value of various hematological markers, clinical, and demographic data for DPN. Results: Among 400 participants, 57% (n = 228) had abnormal NCS results indicative of DPN. Significant differences were observed in the abnormal-NCS group, including older age, longer diabetes duration, higher levels of fasting plasma glucose, HbA1c, and apolipoprotein B, along with lower eGFR, HDL-C, and Apo A-I levels. Notably, negative correlations were found between HDL-C, Apo A-I, vitamin B12, and specific NCS measurements, while positive correlations existed with sural sensory nerve amplitudes. Multivariate analysis highlighted the importance of age, diabetes duration, hyperglycemia, and specific hematologic markers in predicting DPN. Conclusions: The findings confirm that NCSs, combined with hematologic testing, can effectively identify DPN in T2DM patients. Consistent with prior research, prolonged hyperglycemia and nephropathy progression are strongly linked to DPN development. Additionally, lower levels of HDL-C, Apo A-I, and vitamin B12 are associated with the condition, suggesting their potential utility in early diagnostic protocols.

The properties of TREM1 and its emerging role in pain-related diseases

The TREM1 receptor, a member of the TREMs family, is expressed by myeloid cells and functions as an initiator or enhancer of the inflammatory response, playing a pivotal role in the regulation of inflammation. In recent years, it has been found that TREM1-mediated inflammatory response is involved in the regulation of pain-related diseases. This article provides an extensive review on the structural characteristics and distribution patterns, ligand, signaling pathways, inhibitors, and pathophysiological roles of TREM1 in pain disorders aiming to further elucidate its biological function and offer novel insights for clinical interventions targeting pain-related diseases.

Risk factors for residual neuropathic pain using specific screening tools in postoperative patients with ossification of the posterior longitudinal ligament of the cervical spine

PURPOSE

Ageing, long illness duration, and poor preoperative Japanese Orthopaedic Association (JOA) score were reported to be risk factors for residual pain after cervical ossification of the posterior longitudinal ligament (cOPLL). In this study, we focused on residual neuropathic pain (NeP) and aimed to elucidate risk factors for residual NeP after cOPLL.

METHODS

Total of 234 patients who underwent cOPLL surgery were included. NeP was evaluated using painDETECT (PDQ) and Spine painDETECT (SPDQ) questionnaires. Score of ≥ 13 / ≥ 0 was defined as NeP for PDQ/SPDQ. Patient backgrounds factors, preoperative radiographic factors and surgical factors were reviewed, and comparisons between the NeP(+) and NeP(-) groups were made. Independent risk factors for residual NeP were evaluated using multiple logistic regression analysis.

RESULTS

Prevalence of residual NeP after cOPLL was 22.6% on PDQ and 55.1% on SPDQ. Preoperative JOA score was significantly lower in the NeP(+) group for PDQ compared with that in the NeP(-) group. Additionally, cervical lordosis angle was significantly lower in the NeP(+) group for SPDQ compared with that in the NeP(-) group. Following multiple logistic regression analysis, poor preoperative JOA score was identified as a risk factor for NeP on the PDQ. Poor preoperative JOA score and low cervical lordosis angle were identified as risk factors using the SPDQ.

CONCLUSIONS

We found high prevalence of residual NeP after cOPLL. Patients with a poor preoperative JOA score and low cervical lordosis angle might be at risk for residual NeP after surgery evaluated by PDQ or SPDQ and should be monitored with greater care after surgery.

(-) - (11R, 12S)-mefloquine ameliorates neuropathic pain by modulating Cx36-ER stress interaction in the pain-related central nervous system in rats

AIMS

To explore the specific molecular and cellular mechanisms of (-) - Mefloquine (one of Mefloquine's enantiomers) in modulating the interaction between Connexin 36 (Cx36) and endoplasmic reticulum stress (ERS) both in rats with CCI-induced neuropathic pain and in tunicamycin-induced ERS cells.

MATERIALS AND METHODS

The authors conducted chronic constriction injury (CCI) in rats to induce neuropathic pain and established the ERS model in SH-SY5Y cells to mimic the stress state after neuropathic pain. The study employed behavioral tests and various molecular biology techniques, including Western blot analysis, cell transfection, and co-immunoprecipitation (co-IP).

KEY FINDINGS

In vivo, we found that (-) - MQ treatment alleviated CCI-induced ERS to regulate the cytoplasmic Cx36 by inhibiting the activation of PERK in spinal cord and ATF-6 in hippocampus, thereby ameliorating neuropathic pain significantly. In vitro, (-) - MQ not only promoted Cx36 synthesis in the ER and inhibited the excessive transport of Cx36 from the ER to the Golgi apparatus, but also interrupted the binding of Cx36 with calmodulin (CaM), which led to diminished junction formation as indicated by the reduced over-stacking of Cx36 on the membrane of the ERS-exposed cells. Together, these findings clarified that (-) - MQ could ameliorate neuropathic pain through modulating Cx36-ERS interactions within pain-associated regions of the central nervous system in CCI rats.

SIGNIFICANCE

This study, for the first time, elucidated the cellular and molecular mechanisms of (-) - MQ in modulating Cx36-ERS interaction in neuropathic pain, thereby providing new therapeutic options for clinical treatment.

Exploratory study on the ascending pain pathway in patients with chronic neck and shoulder pain based on combined brain and spinal cord diffusion tensor imaging

Objective

To explore the changes in the white matter microstructure of the ascending pain conduction pathways in patients with chronic neck and shoulder pain (CNSP) using combined brain and spinal cord diffusion tensor imaging techniques, and to assess its correlation with clinical indicators and cognitive functions.

Materials and methods

A 3.0T MRI scanner was used to perform combined brain and spinal cord diffusion tensor imaging scans on 31 CNSP patients and 24 healthy controls (HCs), extracting the spinothalamic tract (STT) and quantitatively analyzing the fractional anisotropy (FA) and mean diffusivity (MD) which reflect the microstructural integrity of nerve fibers. Additionally, these differences were subjected to partial correlation analysis in relation to Visual Analog Scale (VAS) scores, duration of pain, Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS).

Results

Compared to HCs, CNSP patients showed decreased mean FA values and increased mean MD values in bilateral intracranial STT compared to the HC group, but two-sample t-test results indicated no statistically significant differences (p > 0.05). FA values of the left STT (C2 segment, C5 segment) and right STT (C1 segment, C2 segment) were significantly decreased in bilateral cervical STTs of CNSP patients; MD values of the left STT (C1 segment, C2 segment, C5 segment) and right STT (C1 segment, C5 segment) were significantly increased (p < 0.05). Partial correlation analysis results showed that FA values of STT in CNSP patients were negatively correlated with VAS scores, duration of pain, SAS scores, and SDS scores, while MD values were positively correlated with VAS scores and duration of pain (Bonferroni p < 0.05).

Conclusion

This research identified that patients with CNSP exhibited reduced mean FA and increased mean MD in the bilateral intracranial STT, although these differences were not statistically significant (p > 0.05). Conversely, significant abnormalities were observed in specific segments of the bilateral cervical STT (p < 0.05), which were also correlated with variations in pain intensity, illness duration, and levels of anxiety and depression. These findings contribute a novel neuroimaging perspective to the evaluation and elucidation of the pathophysiological mechanisms underlying chronic pain in the ascending conduction pathways.

Electroacupuncture Regulates Macrophage Polarization to Alleviate the Neuropathic Pain Induced by Spared Nerve Injury

Purpose

The current therapeutic strategies for neuropathic pain have limited efficacy. The activation of macrophages and pro-inflammatory responses following peripheral nerve injury can effectively prevent the progression of neuropathic pain. Macrophage polarization to the M2 or M1 (respectively anti- and pro- inflammatory) phenotypes frequently occurs during neuroinflammation. Electroacupuncture (EA) therapy has been shown to exert anti-inflammatory functions in several pain models, and has thus been applied to alleviate neuropathic pain. Therefore, the present study aimed to determine whether EA could reduce neuroinflammation and induce analgesia by regulating macrophage polarization.

Methods

Forty-five male rats were used to create a spared nerve injury (SNI) model of peripheral nerve injury. Subsequently, EA was applied to the ipsilateral huantiao (GB30) and yanglingquan (GB34), and the von Frey assay was conducted to monitor the effect of EA on the paw withdrawal threshold. Immunofluorescence analyses were further performed to detect the effects of EA on interleukin-1β (IL-1β) expression and peripheral macrophage polarization.

Results

EA attenuated pain behavior (P=0.002) and decreased inflammatory cytokines derived from macrophages (P=0.002 in the sciatic nerve; P=0.002 in the dorsal root ganglion, DRG) but not in Schwann (P>0.05) or mast (P>0.05) cells in SNI rats. In addition, EA increased M2 macrophage polarization (P<0.0001 in the sciatic nerve; P=0.001 in the DRG) and decreased M1 macrophage expression (P=0.036 in the sciatic nerve; P=0.022 in the DRG).

Conclusion

These data revealed that EA exerted analgesia by adjusting the polarization of macrophages and inhibiting the IL-1β expressing in macrophages in SNI rats.

Bioinspired Intelligent Electronic Skin for Medicine and Healthcare

Intelligent electronic skin aims to mimic, enhance, and even surpass the functions of biological skin, enabling artificial systems to sense environmental stimuli and interact more naturally with humans. In healthcare, intelligent electronic skin is revolutionizing diagnostics and personalized medicine by detecting early signs of diseases and programming exogenous stimuli for timely intervention and on-demand treatment. This review discusses latest progress in bioinspired intelligent electronic skin and its application in medicine and healthcare. First, strategies for the development of intelligent electronic skin to simulate or even surpass human skin are discussed, focusing on its basic characteristics, as well as sensing and regulating functions. Then, the applications of electronic skin in health monitoring and wearable therapies are discussed, illustrating its potential to provide early warning and on-demand treatment. Finally, the significance of electronic skin in bridging the gap between electronic and biological systems is emphasized and the challenges and future perspectives of intelligent electronic skin are summarized.

Effects of Percutaneous Electrical Stimulation on Chronic Neuropathic Pain: A Retrospective Observational Study

INTRODUCTION

Chronic pain affects millions worldwide, with 15% to 25% being neuropathic due to conditions like diabetic neuropathy and radiculopathy. Neuropathic pain, often described as burning or shooting, includes symptoms like allodynia, significantly impacting the quality of life and posing high economic costs. While pharmacological treatments are common, many patients require more invasive, costly interventions such as spinal cord stimulation. As an alternative, percutaneous electrical nerve stimulation (PENS) therapy (PT) offers a less invasive, cost-effective approach that can be administered outpatient, reducing hospitalization costs and providing psychological benefits like anxiety and stress relief.

AIM

This study aimed to compare the efficacy of PT in the short, medium, and long term in patients affected by chronic neuropathic pain, resistant to conventional pharmacological therapies, using a single active PT probe.

METHODS

A total of 100 patients were enrolled for the first PT procedure, and 190 procedures were performed from 2021 to 2023. Excluding those for whom pain could not be detected during follow-up, 41 patients were enrolled, to whom only one PT procedure was performed (Group I). Fourteen patients were enrolled, to whom two PT treatments were performed (Group II), and finally, eight patients were enrolled, to whom three or more PT treatments were performed (Group III). Therefore, a total of 63 patients were enrolled, and 106 PT procedures were performed with pain detected according to the Numeric Pain Scale (NRS) during the entire follow-up period. All patients who presented a trigger point and a specific nevus path or who presented a specific allodynic area caused by a surgical scar were treated.

RESULTS

The group of patients who showed a greater decrease in pain from T0 (baseline) to T1 (three hours after PT) were those who underwent two PT sessions (-52.7%, p = .001). The greatest percentage decrease between before the procedure and seven days after the PT was obtained in the group of patients who underwent three or more PT sessions (T0 4.9 vs. T2 2.9, -40.8%, p < .001). The same group of patients also showed the greatest decrease in pain four weeks after the PT (T0 4.9 vs. T3 3.1, -36.7%, p < .001).

CONCLUSION

PT appears to be an alternative therapy to pharmacological and infiltrative therapy against chronic neuropathic pain.

MTOR Promotes Astrocyte Activation and Participates in Neuropathic Pain through an Upregulation of RIP3

Neuropathic pain (NP), a chronic pain condition, is the result of abnormalities in both central and peripheral pain conduction pathways. Here, we investigated the underlying mechanisms associated with this effect. We found that following chronic constriction injury (CCI) surgery, there was an increase of mTOR in astrocytes and an activation of astrocytes within the spinal cord. Pharmacological inhibition of mTOR reversed CCI-induced hyperalgesia and neuroinflammation. Moreover, knockdown of astrocytic mTOR rescued the downregulation of spinal glutamate metabolism-related protein expression, underscoring the pivotal role of mTOR in modulating this pathway. Intriguingly, we observed that overexpression of mTOR, achieved via intrathecal administration of TSC2-shRNA, led to an upregulation of RIP3. Notably, pharmacological inhibition of RIP3, while ineffective in modulating mTOR activation, effectively eliminated the mTOR-induced astrocyte activation. Mechanistically, we found that mTOR controlled the expression of RIP3 in astrocytes through ITCH-mediated ubiquitination and an autophagy-dependent degradation. Taken together, our results reveal an unanticipated link between mTOR and RIP3 in promoting astrocyte activation, providing new avenues of investigation directed toward the management and treatment of NP.

The Voltage-Gated Calcium Channel α2δ Subunit in Neuropathic Pain

Neuropathic pain (NP) is a chronic pain caused by injury or disease of the somatosensory nervous system, or it can be directly caused by disease. It often presents with clinical features like spontaneous pain, hyperalgesia, and dysesthesia. At present, voltage-gated calcium ion channels (VGCCs) are known to be closely related to the development of NP, especially the α2δ subunit. The α2δ subunit is a regulatory subunit of VGCCs. It exists mainly in the brain and peripheral nervous system, especially in nerve cells, and it plays a crucial part in regulating presynaptic and postsynaptic functions. Furthermore, the α2δ subunit influences neuronal excitation and pain signaling by promoting its expression and localization through binding to VGCC-related subunits. The α2δ subunit is widely used in the management of NP as a target of antiepileptic drugs gabapentin and pregabalin. Although drug therapy is one of the treatments for NP, its clinical application is limited due to the adverse reactions caused by drug therapy. Therefore, further research on the therapeutic target α2δ subunit is needed, and attempts are made to obtain an effective treatment for relieving NP without side effects. This review describes the current associated knowledge on the function of the α2δ subunit in perceiving and modulating NP.

Influence of Intraoperative Pain Management on Postoperative Delirium in Elderly Patients: A Prospective Single-Center Randomized Controlled Trial

INTRODUCTION

Intraoperative analgesia and sedation are closely related to postoperative delirium. Depth of sedation based on bispectral index (BIS) guidance has been shown to reduce the occurrence of postoperative delirium (POD). However, the correlation between intraoperative analgesia levels and POD is unclear. The aim of this study was to investigate the effect of intraoperative analgesic management guided by the nociceptive stimulus index (NOX) on postoperative delirium.

METHODS

In this prospective single-center randomized controlled study, elderly patients aged 65 and above, who are scheduled to undergo unilateral total knee arthroplasty (TKA), were allocated into two groups: the routine monitoring group (group R), which solely monitored patient sedation levels using BIS; and the NOX monitoring group (group N), which monitored patient analgesic levels using NOX based on BIS-monitored sedation levels. The primary outcome was the incidence of postoperative delirium within 3 days after surgery, using the confusion assessment method (CAM).

RESULTS

From May 2022 to December 2022, a total of 240 patients were randomized; 12 were excluded because of failure to meet experimental conditions or were lost to follow-up. Patients in group N had a lower incidence rate (%) of POD on the first day compared to those in group R (8 (7%) vs 18 (16%), P = 0.041). The dosage of remifentanil administered in group N was significantly higher than that in group R (927.07 ± 268.09 vs 882.32 ± 187.91 mg, P = 0.002).

CONCLUSIONS

Appropriate intraoperative analgesia guided by NOX is associated with POD. When sedation levels were consistent, the incidence of POD was significantly reduced in older patients with NOX-guided analgesic management during unilateral TKA surgery.

Early CRPS Is a Heterogeneous Condition: Results From a Latent Class Analysis

BACKGROUND

Complex regional pain syndrome (CRPS) is a debilitating condition characterised by significant heterogeneity. Early diagnosis is critical, but limited data exists on the condition's early stages. This study aimed to characterise (very) early CRPS patients and explore potential subgroups to enhance understanding of its mechanisms.

METHODS

A total of 113 early CRPS patients were recruited, with 89 undergoing physical assessments. Data included demographic information, work-related factors, CRPS history and clinical features, body perception disturbances, quantitative sensory testing (QST), and a visuospatial attention task.

RESULTS

QST identified deficits in detecting thermal and mechanical stimuli, alongside increased sensitivity to thermal and blunt pressure painful stimuli. Participants reported body perception disturbances similar to those of persistent CRPS. Visuospatial biases were observed in two subgroups of patients. Latent class analysis (LCA) of 85 participants, based on five clinical parameters, identified four profiles: Mild, Moderate, Body Representation Disturbance (BRD), and Pressure Allodynia CRPS. The Mild and Moderate profiles were associated with higher-intensity trauma, with the latter showing worse outcomes. BRD and Pressure Allodynia CRPS followed mild trauma but exhibited the poorest outcomes. BRD CRPS displayed significant body perception disturbances, while Pressure Allodynia CRPS presented the highest sensitivity to pressure and psychosocial risk of chronification. Neither condition duration nor skin temperature effectively distinguished subgroups.

CONCLUSIONS

These findings emphasise the heterogeneity within (very) early CRPS patients and support the absence of a minimum required duration prior to the CRPS diagnosis. Central/systemic mechanisms may play critical roles in severe cases.

SIGNIFICANCE

This study identifies distinct (very) early CRPS profiles, suggesting different pathophysiological mechanisms and challenging traditional classifications. It paves the way for improved diagnosis and tailored treatments.

Systemic antihyperalgesic effect of a novel conotoxin from Californiconus californicus in an inflammatory pain model

Introduction

This study explores the analgesic potential of the novel conotoxin O1_cal6.4b, derived from Californiconus californicus, as a candidate for pain management in a model of inflammatory pain.

Methods

O1_cal6.4b was systemically administered to Wistar rats, and its effects on thermal hyperalgesia and motor coordination were evaluated. Comparative analyses were conducted against O1_cal6.4d, ω-MVIIA, and standard analgesics (morphine, dexamethasone, and diclofenac). Structural differences between O1_cal6.4b and O1_cal6.4d were examined using in silico modeling and molecular dynamics simulations.

Results

Systemic administration of O1_cal6.4b significantly reduced thermal hyperalgesia in a dose-dependent manner without impairing motor coordination. The analgesic effect of O1_cal6.4b was superior to that of O1_cal6.4d, ω-MVIIA, and standard analgesics. Structural analyses revealed notable differences between O1_cal6.4b and O1_cal6.4d, suggesting unique functional properties.

Discussion

The findings indicate that O1_cal6.4b exhibits a promising analgesic profile with advantages over traditional opioid-based therapies. These results underscore the molecular diversity of conotoxins and highlight their potential as innovative analgesic treatments. Further research is needed to elucidate the mechanism of action of this novel conotoxin.

NaHS modulates astrocytic EAAT2 expression to impact SNI-induced neuropathic pain and depressive-like behaviors

The potential role of hydrogen sulfide (H2S) in the modulation of neuropathic pain is increasingly recognized. This study investigated the therapeutic effect of intraperitoneal injection of the H2S donor sodium hydrosulfide (NaHS) on neuropathic pain. Utilizing the spared nerve injury (SNI) model in mice, the research investigates the role of astrocytes and the excitatory neurotransmitter glutamate in chronic pain. The findings reveal that sodium hydrosulfide (NaHS), an H2S donor, effectively enhances the mechanical pain threshold and thermal pain escape latency in SNI mice. The study further demonstrates NaHS's potential in reducing glutamate levels in the spinal cord and the discharge frequency of neurons in the primary somatosensory cortex hindlimb region (S1HL) brain area, suggesting a novel therapeutic approach for neuropathic pain through the modulation of astrocyte function and EAAT2 expression.

Abnormal alterations in structure-function coupling at the modular level in patients with postherpetic neuralgia

To investigate the presence of modular loss of coupling and abnormal alterations in functional and structural networks in the brain networks of patients with postherpetic neuralgia (PHN). We collected resting-state functional magnetic resonance imaging data and diffusion tensor imaging data from 82 healthy controls (HCs) and 71 PHN patients, generated structural connectivity (SC) and functional connectivity (FC) networks, and assessed the corresponding clinical information assessment. Based on AAL(90) mapping, the brain network was divided into 9 modules, and the structural-functional connectivity (SC-FC) coupling was compared at the whole-brain level and within the modules, as well as alterations in the topological properties of the brain network in the patient group. Finally, correlation analyses were performed using the following clinical scales: Visual Analogue Scale (VAS), Hamilton Anxiety Scale (HAMA), and Hamilton Depression Scale (HAMD). Compared with HCs, patients with PHN had reduced global efficiency (Eg) and local efficiency (Eloc) of structural and functional networks. The FC in the PHN group presented abnormal node clustering coefficients (NCp), local node efficiencies (NLe), and node efficiencies (Ne), and the SC presented abnormal node degrees (Dc), NCp, NLe, characteristic path lengths (NLp), and Ne. In addition, SC-FC coupling was reduced in the patient default network (DMN), salient network (SN), and visual network (VIS). Moreover, the degree of impairment of graph theory indicators was significantly positively correlated with scales such as VAS scores, and the coupling of modules was significantly negatively correlated with the early course of the patient's disease. Large-scale impaired topological properties of the FC and SC networks were observed in patients with PHN, and SC-FC decoupling was detected in these modules of the DMN, SN, and VIS. These aberrant alterations may have led to over-transmission of pain information or central sensitization of pain.

Quantification of crisugabalin (HSK16149) in biological matrix by LC-MS/MS method: An application to rat pharmacokinetic and tissue distribution studies

Crisugabalin (HSK16149), a novel VGCC α2δ ligand, has been approved for the treatment of adult diabetic peripheral neuropathic pain (DPNP) and postherpetic neuralgia (PHN). In this study, an LC-MS/MS method was developed for the determination of crisugabalin in rat plasma and tissues homogenate. Samples were extracted by protein precipitation and separated on a Hypersil GOLD aQ column with methanol and 2 mM ammonium acetate in water containing 0.1 % formic acid as mobile phase. Crisugabalin and its internal standard HSK7891 were ionized by electrospray ionization source and detected by multiple reaction monitoring with transitions of m/z 210.9 → 134.4 and m/z 246.0 → 129.3. Over the range of 0.0100-10.0 μg/mL, the selectivity, linearity, precision and accuracy, matrix effect, stability, recovery and dilution integrity of crisugabalin were validated in rat plasma. Validation was also performed in rat liver homogenate at concentrations ranging from 0.0200-20.0 μg/g. The method was then successfully applied to determine the pharmacokinetics and tissue distribution of crisugabalin. In rats, orally administered crisugabalin was completely and rapidly absorbed with a peak time of about 0.57 h, and was mainly distributed to kidney, bladder and liver tissues. Crisugabalin exhibited linear pharmacokinetics over the oral dose range of 3-30 mg/kg.

Intranasal Administration of the Combination of Dextro-Ketamine and Dexmedetomidine for Treatment of Diabetic Neuropathic Pain in Rats

Introduction

Diabetes mellitus (DM) has become a public health problem, which is associated with high morbidity and mortality, due to the chronic complications, such as diabetic neuropathy. Current recommendations for the treatment of neuropathic pain achieve a reduction of 30% in only 30% of cases. Therefore, it is necessary to identify new therapeutic approaches to improve the quality of life of diabetic patients.

Methods

This work evaluated the antinociceptive effect of intranasal administration of the combination of dextro-ketamine (keta), a non-competitive glutamatergic receptor antagonist, and dexmedetomidine (DEX), a selective alpha2-adrenergic agonist, in rats with neuropathic pain induced by streptozotocin-DM.

Results

The thermal hyperalgesia and mechanical allodynia observed in DM model are reduced with the intranasal administration of the combination of keta and DEX (200 + 0.10 μg/kg) after 3 days of treatment. The antinociceptive action could be due to reduction of Ca2+ influx with lower glutamate release and reduced excitability through the activation of alpha2-adrenergic receptors by DEX and reduction of NMDA receptor activation by glutamate with lower excitability due to the antagonism produced by keta. DM induced increased expression of glial fibrillary acid protein (GFAP) and tumor necrosis factor-alpha (TNF-alpha) detected by immunohistochemistry, indicating greater astrocyte activity and intense inflammatory response. Intranasal administration for 10 days of the combination of low doses of keta and DEX promoted an intense decrease in the expression of both GFAP and TNF-alpha, indicating lower activation of astrocytes in the spinal cord and reduced production and release of TNF-alpha, favoring the reduction of inflammation.

Conclusion

Intranasal administration of low doses of keta with DEX could be a new therapeutic approach to reduce neuropathic pain and consequently improve the quality of life of diabetic patients.

A novel approach to completely alleviate peripheral neuropathic pain in human patients: insights from preclinical data

Neuropathic pain is a pervasive health concern worldwide, posing significant challenges to both clinicians and neuroscientists. While acute pain serves as a warning signal for potential tissue damage, neuropathic pain represents a chronic pathological condition resulting from injury or disease affecting sensory pathways of the nervous system. Neuropathic pain is characterized by long-lasting ipsilateral hyperalgesia (increased sensitivity to pain), allodynia (pain sensation in response to stimuli that are not normally painful), and spontaneous unprovoked pain. Current treatments for neuropathic pain are generally inadequate, and prevention remains elusive. In this review, we provide an overview of current treatments, their limitations, and a discussion on the potential of capsaicin and its analog, resiniferatoxin (RTX), for complete alleviation of nerve injury-induced neuropathic pain. In an animal model of neuropathic pain where the fifth lumbar (L5) spinal nerve is unilaterally ligated and cut, resulting in ipsilateral hyperalgesia, allodynia, and spontaneous pain akin to human neuropathic pain. The application of capsaicin or RTX to the adjacent uninjured L3 and L4 nerves completely alleviated and prevented mechanical and thermal hyperalgesia following the L5 nerve injury. The effects of this treatment were specific to unmyelinated fibers (responsible for pain sensation), while thick myelinated nerve fibers (responsible for touch and mechanoreceptor sensations) remained intact. Here, we propose to translate these promising preclinical results into effective therapeutic interventions in humans by direct application of capsaicin or RTX to adjacent uninjured nerves in patients who suffer from neuropathic pain due to peripheral nerve injury, following surgical interventions, diabetic neuropathy, trauma, vertebral disc herniation, nerve entrapment, ischemia, postherpetic lesion, and spinal cord injury.

H3K27 Trimethylation-Mediated Downregulation of miR-216a-3p in Sensory Neurons Regulates Neuropathic Pain Behaviors via Targeting STIM1

Although the therapeutic potential of microRNA-mediated gene regulation has been investigated, its precise functional regulatory mechanism in neuropathic pain remains incompletely understood. In this study, we elucidate that miR-216a-3p serves as a critical noncoding RNA involved in the modulation of trigeminal-mediated neuropathic pain. By conducting RNA-seq and qPCR analysis, we observed a notable decrease of miR-216a-3p in the injured trigeminal ganglia (TG) of male rats. Intra-TG administration of miR-216a-3p agomir or lentiviral-mediated overexpression of miR-216a-3p specifically in sensory neurons of injured TGs alleviated established neuropathic pain behaviors, while downregulation of miR-216a-3p (pharmacologically or genetically) in naive rats induced pain behaviors. Moreover, nerve injury significantly elevated the histone H3 lysine-27 (H3K27) trimethylation (H3K27me3) levels in the ipsilateral TG, thereby suppressing the SRY-box TF 10 (SOX10) binding to the miR-216a-3p promoter and resulting in the reduction of miR-216a-3p. Inhibiting the enzymes responsible for catalyzing H3K27me3 restored the nerve injury-induced reduction in miR-216a-3p expression and markedly ameliorated neuropathic pain behaviors. Furthermore, miR-216a-3p targeted stromal interaction molecule 1 (STIM1), and the decreased miR-216a-3p associated with neuropathic pain caused a significant upregulation in the protein abundance of STIM1. Conversely, overexpression of miR-216a-3p in the injured TG suppressed the upregulation of STIM1 expression and reversed the mechanical allodynia. Together, the mechanistic understanding of H3K27me3-dependent SOX10/miR-216a-3p/STIM1 signaling axial in sensory neurons may facilitate the discovery of innovative therapeutic strategies for neuropathic pain management.

miR-363-5p protects from neuropathic pain in chronic constriction injury (CCI) rat models and regulates Schwann cell injury via negatively modulating SERPING1

OBJECTIVES

Due to the complex and unclear pathogenesis of neuropathic pain, there is a lack of effective therapeutic strategy. miR-363-5p was considered of great potential in mediating the development of neuropathic pain, which has not been confirmed with direct evidence. This study evaluated the role of miR-363-5p in neuropathic pain with animal and cell models, aiming to reveal the potential of miR-363-5p in target therapy of neuropathic pain.

METHODS

Chronic constriction injury (CCI) rat models were established as the neuropathic pain model. The expression of miR-363-5p and its target was evaluated by PCR. The painology behaviors were evaluated to assess the function of miR-363-5p. Schwann cells were induced with LPS mimicking cell injury during neuropathic pain. Inflammation and cell growth were estimated by ELISA and CCK8 assays.

RESULTS

Significant downregulation of miR-363-5p and upregulation of SERPING1 were observed in CCI rats. miR-363-5p negatively regulated SERPING1 in CCI rats and LPS-induced Schwann cells. Overexpressing miR-363-5p could improve pain threshold and alleviate inflammation in CCI rats. It also a ttenuated LPS-induced inflammation and reduced proliferation in Schwann cells. The overexpression of SERPING1 could reverse the protective effect of miR-363-5p on CCI rats and LPS-induced Schwann cell injury.

CONCLUSION

miR-363-5p protected from neuropathic pain via alleviating Schwann cell injury by negatively modulating SERPING1.

Discovery of E0199: A novel compound targeting both peripheral NaV and KV7 channels to alleviate neuropathic pain

This research study focuses on addressing the limitations of current neuropathic pain (NP) treatments by developing a novel dual-target modulator, E0199, targeting both NaV1.7, NaV1.8, and NaV1.9 and KV7 channels, a crucial regulator in controlling NP symptoms. The objective of the study was to synthesize a compound capable of modulating these channels to alleviate NP. Through an experimental design involving both in vitro and in vivo methods, E0199 was tested for its efficacy on ion channels and its therapeutic potential in a chronic constriction injury (CCI) mouse model. The results demonstrated that E0199 significantly inhibited NaV1.7, NaV1.8, and NaV1.9 channels with a particularly low half maximal inhibitory concentration (IC50) for NaV1.9 by promoting sodium channel inactivation, and also effectively increased KV7.2/7.3, KV7.2, and KV7.5 channels, excluding KV7.1 by promoting potassium channel activation. This dual action significantly reduced the excitability of dorsal root ganglion neurons and alleviated pain hypersensitivity in mice at low doses, indicating a potent analgesic effect without affecting heart and skeletal muscle ion channels critically. The safety of E0199 was supported by neurobehavioral evaluations. Conclusively, E0199 represents a ground-breaking approach in NP treatment, showcasing the potential of dual-target small-molecule compounds in providing a more effective and safe therapeutic option for NP. This study introduces a promising direction for the future development of NP therapeutics.