Maresin 1 promotes nerve regeneration and alleviates neuropathic pain after nerve injury

EZH2-dependent myelination following sciatic nerve injury

JOURNAL/nrgr/04.03/01300535-202508000-00028/figure1/v/2024-09-30T120553Z/r/image-tiff Demyelination and remyelination have been major focal points in the study of peripheral nerve regeneration following peripheral nerve injury. Notably, the gene regulatory network of regenerated myelin differs from that of native myelin. Silencing of enhancer of zeste homolog 2 (EZH2) hinders the differentiation, maturation, and myelination of Schwann cells in vitro. To further determine the role of EZH2 in myelination and recovery post-peripheral nerve injury, conditional knockout mice lacking Ezh2 in Schwann cells (Ezh2fl/fl;Dhh-Cre and Ezh2fl/fl;Mpz-Cre) were generated. Our results show that a significant proportion of axons in the sciatic nerve of Ezh2-depleted mice remain unmyelinated. This highlights the crucial role of Ezh2 in initiating Schwann cell myelination. Furthermore, we observed that 21 days after inducing a sciatic nerve crush injury in these mice, most axons had remyelinated at the injury site in the control nerve, while Ezh2fl/fl;Mpz-Cre mice had significantly fewer remyelinated axons compared with their wild-type littermates. This suggests that the absence of Ezh2 in Schwann cells impairs myelin formation and remyelination. In conclusion, EZH2 has emerged as a pivotal regulatory factor in the process of demyelination and myelin regeneration following peripheral nerve injury. Modulating EZH2 activity during these processes may offer a promising therapeutic target for the treatment of peripheral nerve injuries.

Formoterol alters chemokine expression and ameliorates pain behaviors after moderate spinal cord injury in female mice

Secondary spinal cord injury (SCI) is characterized by increased cytokines and chemokines at the site of injury that have been associated with the development of neuropathic pain. Nearly 80% of SCI patients report suffering from chronic pain, which is poorly managed with available analgesics. While treatment with the US Food and Drug Administration-approved β2-adrenergic receptor agonist formoterol improves various aspects of recovery post-SCI in vivo, its effects on cytokines, chemokines, and neuropathic pain remain unknown. Female mice were subjected to moderate (60 kilodynes [kdyn]) or severe (80 kdyn) SCI followed by daily treatment with vehicle or formoterol (0.3 mg/kg, i.p.) beginning 8 hours after injury. The expression of proinflammatory cytokines/chemokines, such as interferon gamma-induced protein 10, macrophage inflammatory protein 1a, monocyte chemoattractant protein 1, B-cell attracting chemokine 1, and nuclear factor kappa-light-chain-enhancer of activated B-cells, was increased in the injury site of vehicle-treated mice 24 hours post-SCI, which was ameliorated with formoterol treatment, regardless of injury severity. Thermal hyperalgesia and mechanical allodynia, as measured by Hargreaves infrared apparatus and von Frey filaments, respectively, were assessed prior to SCI and then weekly beginning 21 days post-injury (DPI). While all injured mice exhibited decreased withdrawal latency following thermal stimulation compared with baseline, formoterol treatment reduced this response ∼15% by 35 DPI. Vehicle-treated mice displayed significant mechanical allodynia, as evidenced by a 55% decrease in withdrawal threshold from baseline. In contrast, mice treated with formoterol maintained a consistent withdrawal time at all times tested. These data indicate that formoterol reduces inflammation post-SCI, likely contributing to mitigation of neuropathic pain and further supporting the therapeutic potential of this treatment strategy. SIGNIFICANCE STATEMENT: Chronic pain is a detrimental consequence of spinal cord injury (SCI). We show that treatment with the US Food and Drug Administration-approved drug formoterol after SCI decreases injury site proinflammatory chemo-/cytokines and alters markers of glial cell activation and infiltration. Additionally, formoterol treatment improves locomotor function and body composition, and decreases lesion volume. Finally, formoterol treatment decreased mechanical allodynia and thermal hyperalgesia post-SCI. These data are suggestive of the mechanism of formoterol-induced recovery, and further indicate its potential as a therapeutic strategy for SCI.

Pathophysiology-Directed Engineering of a Combination Nanoanalgesic for Neuropathic Pain

Neuropathic pain, one of the most refractory pain diseases, remains a formidable medical challenge. There is still an unmet demand for effective and safe therapies to address this condition. Herein, a rat model of nerve injury-induced neuropathic pain is first established to explore its pathophysiological characteristics. Recognizing the role of neuroinflammation, an inflammation-resolving amphiphilic conjugate PPT is designed and synthesized by simultaneously conjugating polyethylene glycol, phenylboronic acid pinacol ester, and Tempol onto a cyclic scaffold. PPT can self-assemble into nanomicelles (termed PPTN). Following intravenous injection, PPTN preferentially accumulates in the injured nerve, ameliorates the neuroinflammatory milieu, and promotes nerve regeneration, thereby shortening neuropathic pain duration in rats. Moreover, the Ca2+ channel α2δ1 subunit is identified as a therapeutic target by RNA-sequencing analysis of the injured nerve. Based on this target, a mimicking peptide (AD peptide) is screened as an analgesic. By packaging AD peptide into PPTN, a combination nano-analgesic APTN is developed. Besides potentiated anti-hyperalgesic effects due to site-specific delivery and on-demand release of AD peptide at target sites, APTN simultaneously inhibits neuroinflammation and promotes nerve regeneration by reprogramming macrophages via regulating MAPK/NF-kB signaling pathways and NLRP3 inflammasome activation, thus affording synergistic efficacies in treating nerve injury-induced neuropathic pain.

Maladaptive changes in the homeostasis of AEA-TRPV1/CB1R induces pain-related hyperactivity of nociceptors after spinal cord injury

BACKGROUND

Neuropathic pain resulting from spinal cord injury (SCI) is associated with persistent hyperactivity of primary nociceptors. Anandamide (AEA) has been reported to modulate neuronal excitability and synaptic transmission through activation of cannabinoid type-1 receptors (CB1Rs) and transient receptor potential vanilloid 1 (TRPV1). However, the role of AEA and these receptors in the hyperactivity of nociceptors after SCI remains unclear.

RESULTS

In this study, we investigated the effects of AEA and its receptors on the hyperexcitability of mouse dorsal root ganglion (DRG) neurons after SCI. Using a whole-cell patch-clamp technique, we found that the timing of SCI-induced hyperexcitability in nociceptors paralleled an increase in the endocannabinoid AEA content. The expression of TRPV1 and CB1R was also upregulated at different time points after SCI. High-dose extracellular administration of AEA increased the excitability of naive DRG neurons, leading to the transition from a rapidly accommodating (RA) hypoexcitable state to a highly excitable non-accommodating (NA) state. These AEA-induced transitions were facilitated by increased TRPV1 transcription. Pharmacological and Ca2+ imaging experiments revealed that AEA induced hyperexcitability in nociceptors after SCI via the AEA-TRPV1-Ca2+ pathway, whereas activation of CB1Rs reduced SCI-induced hyperexcitability and maintained cytosolic Ca2+ concentration ([Ca2+]cyto) at low levels in the early stages of SCI. As the AEA and TRPV1 levels increased after SCI, adaptive neuroprotection transitioned to a maladaptive hyperactive state, leading to sustained pain.

CONCLUSIONS

Taken together, this study provides new insights into how endocannabinoids regulate nociceptor activity after SCI, offering potential targets for the treatment of neuropathic pain.

A high seizure burden increases brain concentrations of specialized pro-resolving mediators in the Scn1a+/- mouse model of Dravet syndrome

OBJECTIVE

Dravet syndrome is a severe, intractable epilepsy in which 80 % of patients have a de novo mutation in the gene SCN1A. We recently reported that a high seizure burden increased hippocampal concentrations of an array of pro-inflammatory prostaglandins in the Scn1a+/- mouse model of Dravet syndrome. This raised the possibility that a high seizure burden might also trigger the accumulation of specialized pro-resolving mediators that facilitate the resolution of neuroinflammation and brain repair. The present study therefore aimed to examine whether a high seizure burden increased hippocampal concentrations of various specialized pro-resolving mediators in the Scn1a+/- mouse model of Dravet syndrome.

METHODS

Scn1a+/- mice at postnatal day 21 (P21) were primed with a single hyperthermia-induced seizure event to induce a high seizure burden. On P24 primed Scn1a+/- mice with a high seizure burden, unprimed naïve Scn1a+/- mice and wild-type (WT) mice were euthanized and hippocampal tissue was collected for analysis of various specialized pro-resolving mediators using liquid chromatography mass spectrometry.

RESULTS

Scn1a+/- mice with a high seizure burden showed increased hippocampal concentrations of the pro-inflammatory leukotrienes B4 and E4. Further, a high seizure burden increased hippocampal concentrations of various special pro-resolving mediators, including the maresins (maresin1), D-series resolvins (RVD1 and RVD4), and protectin (PCTR1). To further characterize these changes, we determined the mRNA expression of lipoxygenase genes, as these synthetic enzymes are common across classes of specialized pro-resolving mediators. However, hippocampal expression of Alox5, Alox12 and Alox15 were not influenced by a high seizure burden.

SIGNIFICANCE

We report for the first time that a high seizure burden increases the hippocampal concentrations of various specialized pro-resolving mediators in Scn1a+/- mice. This provides a platform for future studies to examine whether modulation of these mediators might be exploited to reduce seizures and facilitate brain repair in intractable epilepsy syndromes.

Preventive and Therapeutic Effects of Intracerebroventricular Administration of Maresin-1 on Lipopolysaccharide-Induced Depression-Like Behaviors in Mice

Enhanced inflammatory and immune responses have been observed in patients with major depressive disorder, pointing to anti-inflammatory substances as potential seeds for developing novel antidepressants. Omega-3 polyunsaturated fatty acid metabolites, such as resolvin D and E series, maresins, and protectins (collectively known as specialized pro-resolving mediators) demonstrate anti-inflammatory effects. This study examined the antidepressant-like effects of maresin-1 (MaR1) on lipopolysaccharide (LPS)-induced depression-like behaviors in mice. Using the tail suspension test (TST) and the forced swim test (FST), we assessed depression-like behaviors 26 and 28 h after intraperitoneal injection of LPS (0.8 mg/kg), respectively. An open field test (OFT) was also conducted to evaluate locomotor activity 24 h after LPS injection. Intracerebroventricular (i.c.v.) injection of MaR1 (10 ng/mouse) immediately after the LPS challenge mitigated the increased immobility time in the TST and FST, without affecting locomotor activity in the OFT, indicating the preventive effects of MaR1 on LPS-induced depression-like behaviors. Furthermore, i.c.v. injection of MaR1 23 h after the LPS challenge reduced the immobility time in both tests, underscoring its therapeutic potential. These findings suggest that MaR1 could be a promising seed for developing novel antidepressants.

Pharmacodynamic insights into maresin 1: Enhancing flap viability via the keap1/Nrf2 axis to control ROS-driven apoptosis and ferroptosis

Random flaps are widely used in tissue reconstruction, but the high incidence of flap necrosis after operation remains a significant challenge. Maresin 1 (MaR1), a mediator derived from docosahexaenoic acid, has been shown to have significant effects in resolving inflammation and promoting tissue regeneration. This study investigated the role of MaR1 in the survival of random flaps. Histological analysis, laser Doppler blood flow imaging, Masson trichrome staining, and survival area analysis were used to assess the viability of the flaps. Apoptosis, ferroptosis, oxidative stress, angiogenesis, and the underlying mechanisms were explored by examining the expression of specific molecules using immunofluorescence, western blotting, and other immunological and molecular biology techniques. The findings demonstrated that MaR1 could improve flap lifespan by significantly reducing oxidative stress, apoptosis, and ferroptosis, as well as by enhancing angiogenesis. The Keap1-Nrf2 pathway was upregulated by MaR1, which inhibited ROS-mediated apoptosis and ferroptosis. The protective effect of MaR1 on flap survival was abolished by ML385. Our findings indicate that MaR1 could be a novel therapeutic agent for enhancing flap treatment outcomes.

Research progress in the mechanisms and functions of specialized pro-resolving mediators in neurological diseases

The nervous system interacts with the immune system through a variety of cellular regulators, signaling pathways, and molecular mechanisms. Disruptions in these interactions lead to the development of multiple neurological diseases. Recent studies have identified that specialized pro-resolving mediators (SPMs) play a regulatory role in the neuroimmune system. This study reviews recent research on the function of SPMs in the inflammatory process and their association with the nervous system. The review aims to provide new perspectives for studying the pathogenesis of neurological diseases and identify novel targets for clinical therapy.

Neuroprotective Effect of Maresin-1 in Rotenone-Induced Parkinson's Disease in Rats: The Putative Role of the JAK/STAT Pathway

Exposure to rotenone results in similar pathophysiological features as Parkinson's disease. Inflammation and oxidative stress are essential to PD pathogenesis. Maresin-1 has potent anti-inflammatory properties and promotes the regression of inflammation function. The current study aimed to evaluate the protective effects of Maresin-1 (MaR1) in rotenone (ROT)-induced PD and whether this protective role is associated with the initiation of the Janus kinase (JAK)-signal transducers and activator of transcription (STAT) signaling pathway. Thirty male Wister rats were classified into control, ROT-treated, and ROT + MaR1-treated groups. Rats underwent rotarod, open field, grip strength, and stepping tests as part of their motor behavioral evaluation. Serum glial cell-derived neurotrophic factor (GDNF) and striatal dopamine, acetylcholine, malondialdehyde (MDA), reduced glutathione (GSH), TNF-α, IL-6, and IL-1β were evaluated. Expression of JAK1 and STAT3 genes was assessed in striatum. Then, the tissue was subjected to histological and immunohistochemical evaluation for caspase-3, GFAP, and NF-kB. The administrated group with rotenone showed significant motor behavioral impairment. This was accompanied by reduced levels of GDNF and dopamine and increased levels of acetylcholine, as well as augmented oxidative stress and inflammatory biomarkers and reduced antioxidant activity. Inflammatory pathways (JAK1/STAT3, caspase-3, and NF-kB) were upregulated. Histopathological changes and upregulation in GFAP immunopositive reaction were observed. Remarkably, MaR1 treatment effectively alleviated behavior, histopathological changes, and biochemical alterations induced by ROT. MaR1 exerts protective effects against ROT-induced PD by its anti-inflammatory, antiapoptotic, and antioxidant properties. MaR1 mechanisms of action may involve modulation of pathways such as JAK/STAT.

Maresin-1 Ameliorates Sepsis-Induced Microglial Activation Through Modulation of the P38 MAPK Pathway

Sepsis is a life-threatening disease characterized by a dysregulated immune response to infection, often leading to neuroinflammation. As a known immunomodulator, Maresin-1 (MaR1) may have potential applications in the treatment of sepsis-induced neuroinflammation, but its effects in this context are unknown. We used a mouse cecum ligation and puncture (CLP)-induced sepsis model and an in vitro lipopolysaccharide (LPS)-induced neuroinflammatory model of BV2 microglia. Expression of microglial cell markers (IBA1, CD11B, CD68, CD86 and CD206) and pro-inflammatory markers (iNOS and COX2) was assessed. The role of MaR1 in regulating the P38 MAPK pathway was explored using the P38 MAPK inhibitor SB203580. In the CLP model, an increased proportion of M1-type microglia was observed, and MaR1 was able to reverse it. However, the combination of SB203580 and MaR1 did not enhance the therapeutic effect compared to SB20580 alone. In vitro experiments, MaR1 inhibited LPS-induced P38 MAPK nuclear translocation and decreased the expression of pro-inflammatory markers such as iNOS and COX2. As with the animal results, no stacking effect could be obtained with the co-administration of SB203580 and MaR1. Our findings suggest that MaR1 attenuates sepsis-induced neuroinflammation mainly by inhibiting phosphorylation of P38 MAPK in microglial cells. This suggests that MaR1 may have a potential therapeutic role in the treatment of sepsis neuroinflammation.

Molecular mechanisms of neuropathic pain

Peripheral neuropathic pain, which occurs after a lesion or disease affecting the peripheral somatosensory nervous system, is a complex and challenging condition to treat. This chapter will cover molecular mechanisms underlying the pathophysiology of peripheral neuropathic pain, focusing on (1) sensitization of nociceptors, (2) neuro-immune crosstalk, and (3) axonal degeneration and regeneration. The chapter will also emphasize the importance of identifying novel therapeutic targets in non-neuronal cells. A comprehensive understanding of how changes at both neuronal and non-neuronal levels contribute to peripheral neuropathic pain may significantly improve pain management and treatment options, expanding to topical application that bypass the side effects associated with systemic administration.

The efficacy and safety of monoclonal antibody therapies for interstitial cystitis/bladder pain syndrome: A meta-analysis of randomized controlled trials

OBJECTIVES

This study aimed to assess the efficacy and safety of monoclonal antibody therapies (MATs) for interstitial cystitis/bladder pain syndrome (IC/BPS).

METHODS

A systematic search was conducted across databases including PubMed, Embase, clinicalTrial.gov, and the Cochrane Library Central Register of Controlled Trials. Randomized controlled trials (RCTs) comparing MATs versus placebo were included. Primary outcomes comprised the Global Response Assessment (GRA) scale and the O'Leary-Sant Interstitial Cystitis Symptom Index (ICSI). Additional analyses encompassed mean daily frequency of voids, the O'Leary-Sant Interstitial Cystitis Problem Index, pain scores, and complications. Statistical analyses were performed using Review Manager 5.3.

RESULTS

Five high-quality RCTs, comprising 263 patients with IC/BPS, were ultimately selected. MATs were generally effective in treating IC/BPS. Patients receiving MATs exhibited a higher satisfaction rate (odds ratio [OR]: 2.7, confidence interval [CI]: 1.31-5.58, p = 0.007) and lower ICSI scores (mean difference [MD]: -1.44, CI: -2.36 to -0.52, p = 0.002). Moreover, MAT recipients experienced reduced pain (MD: -0.53, CI: -0.79 to -0.26, p < 0.0001) and decreased frequency of urination (MD: -1.91, CI: -2.55 to -1.27, p < 0.00001). Importantly, there were no disparities regarding complication incidence in the MAT and control groups.

CONCLUSIONS

The current findings indicate that MATs are effective and safe for treating IC/BPS. Nonetheless, future RCTs with larger sample sizes and long-term follow-up are warranted.

Omega-3 polyunsaturated fatty acids alleviate endoplasmic reticulum stress-induced neuroinflammation by protecting against traumatic spinal cord injury through the histone deacetylase 3/ peroxisome proliferator-activated receptor-γ coactivator pathway

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) attenuate inflammatory responses in the central nervous system, leading to neuroprotective effects. Inhibition of histone deacetylase 3 (HDAC3) has neuroprotective effects after spinal cord injury (SCI) through the SIRT1 pathway, but the pathophysiological mechanisms of SCI are complex and the interactions between ω-3 PUFAs and organelles remain largely unknown. This study aimed to investigate the effect of ω-3 PUFAs on endoplasmic reticulum (ER) stress-induced neuroinflammation through the HDAC3/peroxisome proliferator-activated receptor-γ coactivator (PGC)-1ɑ pathway after SCI. To this end, a contusion-induced SCI rat model was established to evaluate the effects of ω-3 PUFAs on ER stress-mediated inflammation in SCI. ER stress was rapidly induced in spinal cord lesions after SCI and was significantly reduced after ω-3 PUFA treatment. Consistent with reduced ER stress, HDAC3 expression levels and inflammatory responses were decreased, and PGC-1ɑ expression levels were increased after SCI. We found that ω-3 PUFA treatment attenuated ER stress through HDAC3 inhibition, thereby reducing SCI-induced inflammation. Taken together, these results suggest a role for ω-3 PUFA in protecting against SCI-induced neuroinflammation and promoting neurological functional recovery by regulating the histone deacetylase 3/ peroxisome proliferator-activated receptor-γ coactivator pathway.

Fentanyl induces analgesic effect through miR-381-3p/TRPM7 when combined with bupivacaine in subarachnoid injection

Fentanyl combined with bupivacaine in subarachnoid anesthesia exerts a strong synergistic analgesic effect, extending the duration of analgesia. However, the mechanism of enhanced analgesic effect of fentanyl remains elusive. The present study investigated the potential mechanism of the analgesic effect of fentanyl when combined with bupivacaine. The subarachnoid injection (SI) rat model was employed, and SI of fentanyl or/and bupivacaine was used to investigate their analgesic effect. Dorsal root ganglion (DRG)' RNA sequencing (RNA-Seq) and bioinformatics analysis were performed to evaluate the downstream mechanisms of MicroRNAs (miRNAs). Further validation tests included RT-PCR, Western blot, and immunofluorescence. A single SI of fentanyl or bupivacaine decreased the positive responses to stimulation when used alone or in combination. RNA-seq results revealed that miR-381-3p played a role in the fentanyl-driven promotion of analgesia. Bioinformatics analysis and dual-luciferase reporter identified TRPM7 as a direct downstream target gene of miR-381-3p. In vitro, overexpression of miR-381-3p could further block fentanyl-induced expression of TRPM7, p-ERK1/2, CGRP, and SP. In addition, antagomir-381-3p reversed the inhibitory effect of fentanyl on the expression of TRPM7, p-ERK1/2, CGRP, and SP, in vivo; however, TRPM7 siRNA rescued the effect of antagomir-381-3p. In conclusion, fentanyl inhibits p-ERK by targeting TRPM7 via miR-381-3p, lowering the production of CGRP and SP, and ultimately inducing analgesic effects.

Association between human herpes simplex virus and severe headache or migraine among aged 20-49 years: a cross-sectional study

Background and purpose

Previous studies have shown that human herpes simplex virus (HSV) infection may be associated with the onset of headache or migraine. We aimed to investigate the association between HSV infection and severe headache or migraine.

Materials and methods

The cross-sectional data on 5,730 participants aged 20-49 years were obtained from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). We used weighted logistic regression analysis to assess the association between HSV infection (HSV-1 gG-1 and HSV-2 gG-2) and severe headache or migraine, and performed subgroup analyses.

Results

Our study found that women, higher education, higher body mass index, better family conditions, smoking and alcohol consumption were all associated with severe headaches or migraines. After adjusting for confounding factors such as sex, age, race, and education, HSV-2 (+) was still significantly associated with severe headache or migraine (OR = 1.22, 95%CI:1.03-1.46, p = 0.0443). In subgroup analyses, we found that participants with HSV-1 (-) and HSV-2 (+) were also significantly associated with severe headache or migraine (OR = 1.41, 95%CI:1.04-1.91, p = 0.0281).

Conclusion

HSV-2 gG-2(+) was significantly associated with severe headache or migraine.

Downregulation of chloride voltage-gated channel 7 contributes to hyperalgesia following spared nerve injury

Alterations in anion balance potential, along with the involvement of cation-chloride cotransporters, play pivotal roles in the development of hyperalgesia after peripheral nerve injury. Chloride voltage-gated channel seven (CLCN7) is the predominant member of the CLC protein family. Investigations on CLCN7 have focused primarily on its involvement in osteosclerosis and lysosomal storage disorders; nevertheless, its contribution to neuropathic pain has not been determined. In this investigation, we noted high expression of CLCN7 in neurons situated within the spinal dorsal horns and dorsal root ganglions (DRGs). Immunofluorescence analysis revealed that CLCN7 was predominantly distributed among IB4-positive and CGRP-positive neurons. Furthermore, the expression of CLCN7 was observed to be mainly reduced in neurons within the spinal dorsal horns and in small- and medium-sized neurons located in the DRGs of spared nerve injury mice. Knockdown of CLCN7 via siRNA in the DRGs resulted in increased mechanical and thermal hyperalgesia in naïve mice. Furthermore, the excitability of cultured DRG neurons in vitro was augmented upon treatment with CLCN7 siRNA. These findings suggested that CLCN7 downregulation following SNI was crucial for the manifestation of mechanical and thermal hyperalgesia, highlighting potential targeting strategies for treating neuropathic pain.

Rab8a/SNARE complex activation promotes vesicle anchoring and transport in spinal astrocytes to drive neuropathic pain

Neuropathic pain (NPP) remains a clinically challenging condition, driven by the activation of spinal astrocytes and the complex release of inflammatory mediators. This study aimed to examine the roles of Rab8a and SNARE complex proteins in activated astrocytes to uncover the underlying mechanisms of NPP. The research was conducted using a rat model with chronic constriction injury (CCI) of the sciatic nerve and primary astrocytes treated with lipopolysaccharide. Enhanced expression of Rab8a was noted specifically in spinal dorsal horn astrocytes through immunofluorescence. Electron microscopy observations showed increased vesicular transport and exocytic activity in activated astrocytes, which was corroborated by elevated levels of inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α detected through quantitative PCR. Western blot analyses confirmed significant upregulation of Rab8a, VAMP2, and Syntaxin16 in these cells. Furthermore, the application of botulinum neurotoxin type A (BONT/A) reduced the levels of vesicle transport-associated proteins, inhibiting vesicular transport in activated astrocytes. These findings suggest that the Rab8a/SNARE pathway in astrocytes enhances vesicle transport and anchoring, increasing the secretion of bioactive molecules that may play a crucial role in the pathophysiology of NPP. Inhibiting this pathway with BONT/A offers a novel therapeutic target for managing NPP, highlighting its potential utility in clinical interventions.

Research trends on cancer neuroscience: a bibliometric and visualized analysis

Background

Recently, cancer neuroscience has become the focus for scientists. Interactions between the nervous system and cancer (both systemic and local) can regulate tumorigenesis, progression, treatment resistance, compromise of anti-cancer immunity, and provocation of tumor-promoting inflammation. We assessed the related research on cancer neuroscience through bibliometric analysis and explored the research status and hotspots from 2020 to 2024.

Methods

Publications on cancer neuroscience retrieved from the Web of Science Core Collection. CiteSpace, VOSviewer, and Scimago Graphica were used to analyze and visualize the result.

Results

A total of 744 publications were retrieved, with an upward trend in the overall number of articles published over the last 5 years. As it has the highest number of publications (n = 242) and citations (average 13.63 citations per article), the United States holds an absolute voice in the field of cancer neuroscience. The most productive organizations and journals were Shanghai Jiaotong University (n = 24) and Cancers (n = 45), respectively. Monje M (H-index = 53), Hondermarck H (H-index = 42), and Amit M (H-index = 39) were the three researchers who have contributed most to the field. From a global perspective, research hotspots in cancer neuroscience comprise nerve/neuron-tumor cell interactions, crosstalk between the nervous system and other components of the tumor microenvironment (such as immune cells), as well as the impact of tumors and tumor therapies on nervous system function.

Conclusion

The United States and European countries are dominating the field of cancer neuroscience, while developing countries such as China are growing rapidly but with limited impact. The next focal point in this field is likely to be neurotrophic factors. Cancer neuroscience is still in its infancy, which means that many of the interactions and mechanisms between the nervous system and cancer are not yet fully understood. Further investigation is necessary to probe the interactions of the nervous system with cancer cell subpopulations and other components of the tumor microenvironment.

Silicon-induced biofilm improves peripheral nerve defect in rats mediated by VEGF/VEGFR2/ERK

Background: Injury of peripheral nerve capable of regeneration with much poorer prognosis affects people's life quality. The recovery of nerve function after transplantation for peripheral nerve injury remain a worldwide problem. Silicon-induced biofilms as vascularized biological conduits can promote nerve regeneration by encapsulating autologous or allogeneic nerve graft.Objective: We proposed to explore the effect of silicon-induced biofilms on nerves regeneration and whether the VEGF/VEGFR2/ERK pathway was involved in the present study.Methods: Biofilms around the transplanted nerves in peripheral nerve injury rats were induced by silicon. Vascularization and proteins related to VEGF/VEGFR2/ERK were measured. Pathology and morphology of nerves were investigated after encapsulating the transplanted nerves by silicon-induced biofilms.Results: Our results indicated that the biofilms induced by silicon for 6 weeks showed the most intensive vascularization and the optimal effect on nerve regeneration. Moreover, silicon-induced biofilms for 4, 6 and 8 weeks could significantly secrete VEGF with the highest content at week 6 after induction. VEGFR2, VEGF, p-VEGFR2, ERK1, ERK2, p-ERK1 and p-ERK2 were expressed in the biofilms. p-VEGFR2, p-ERK1 and p-ERK2 expression were different at each time point and significantly increased at week 6 compared with that at week 4 or week 8 which was consistent with that 6 week of was the optimum time for biofilms induction to improve the nerve repair after peripheral nerve injury.Conclusion: Our results suggested that combination of silicon-induced autologous vascularized biofilm and autologous transplantation may promote the repair of rat sciatic nerve defect quickly through VEGF/VEGFR2/ERK pathway.

Maresin 1 alleviates neuroinflammation and cognitive decline in a mouse model of cecal ligation and puncture

OBJECTIVES

Inflammation in the central nervous system plays a crucial role in the occurrence and development of sepsis-associated encephalopathy. This study aims to explore the effects of maresin 1 (MaR1), an anti-inflammatory and pro-resolving lipid mediator, on sepsis-induced neuroinflammation and cognitive impairment.

METHODS

Mice were randomly assigned to 4 groups: A sham group (sham operation+vehicle), a cecal ligation and puncture (CLP) group (CLP operation+vehicle), a MaR1-LD group (CLP operation+1 ng MaR1), and a MaR1-HD group (CLP operation+10 ng MaR1). MaR1 or vehicle was intraperitoneally administered starting 1 h before CLP operation, then every other day for 7 days. Survival rates were monitored, and serum inflammatory cytokines [tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6] were measured 24 h after operation using enzyme-linked immunosorbent assay (ELISA). Cognitive function was assessed 7 days after operation using the Morris water maze (MWM) test and novel object recognition (NOR) task. The mRNA expression of TNF-α, IL-1β, IL-6, inducible nitric oxide synthase (iNOS), IL-4, IL-10, and arginase 1 (Arg1) in cortical and hippocampal tissues was determined by real-time reverse transcription PCR (RT-PCR). Western blotting was used to determine the protein expression of iNOS, Arg1, signal transducer and activator of transcription 6 (STAT6), peroxisome proliferator-activated receptor gamma (PPARγ), and phosphorylated STAT6 (p-STAT6) in hippocampal tissue. Microglia activation was visualized via immunofluorescence. Mice were also treated with the PPARγ antagonist GW9662 to confirm the involvement of this pathway in MaR1's effects.

RESULTS

CLP increased serum levels of TNF-α, IL-1β, and IL-6, and reduced body weight and survival rates (all P<0.05). Both 1 ng and 10 ng doses of MaR1 significantly reduced serum TNF-α, IL-1β, and IL-6 levels, improved body weight, and increased survival rates (all P<0.05). No significant difference in efficacy was observed between the 2 doses (all P>0.05). MWM test and NOR task indicated that CLP impaired spatial learning, which MaR1 mitigated. However, GW9662 partially reversed MaR1's protective effects. Real-time RT-PCR results demonstrated that, compared to the sham group, mRNA expression of TNF-α, IL-1β, and iNOS significantly increased in hippocampal tissues following CLP (all P<0.05), while IL-4, IL-10, and Arg1 showed a slight decrease, though the differences were not statistically significant (all P>0.05). Compared to the CLP group, both 1 ng and 10 ng MaR1 decreased TNF-α, IL-1β, and iNOS mRNA expression in hippocampal tissues and increased IL-4, IL-10, and Arg1 mRNA expression (all P<0.05). Immunofluorescence results indicated a significant increase in Iba1-positive microglia in the hippocampus after CLP compared to the sham group (P<0.05). Administration of 1 ng and 10 ng MaR1 reduced the percentage area of Iba1-positive cells in the hippocampus compared to the CLP group (both P<0.05). Western blotting results showed that, compared to the CLP group, both 1 ng and 10 ng MaR1 down-regulated the iNOS expression, while up-regulated the expression of Arg1, PPARγ, and p-STAT6 (all P<0.05). However, the inclusion of GW9662 counteracted the MaR1-induced upregulation of Arg1 and PPARγ compared to the MaR1-LD group (all P<0.05).

CONCLUSIONS

MaR1 inhibits the classical activation of hippocampal microglia, promotes alternative activation, reduces sepsis-induced neuroinflammation, and improves cognitive decline.

Pathology of pain and its implications for therapeutic interventions

Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.

Peripheral Mechanism of Cancer-Induced Bone Pain

Cancer-induced bone pain (CIBP) is a type of ongoing or breakthrough pain caused by a primary bone tumor or bone metastasis. CIBP constitutes a specific pain state with distinct characteristics; however, it shares similarities with inflammatory and neuropathic pain. At present, although various therapies have been developed for this condition, complete relief from CIBP in patients with cancer is yet to be achieved. Hence, it is urgent to study the mechanism underlying CIBP to develop efficient analgesic drugs. Herein, we focused on the peripheral mechanism associated with the initiation of CIBP, which involves tissue injury in the bone and changes in the tumor microenvironment (TME) and dorsal root ganglion. The nerve-cancer and cancer-immunocyte cross-talk in the TME creates circumstances that promote tumor growth and metastasis, ultimately leading to CIBP. The peripheral mechanism of CIBP and current treatments as well as potential therapeutic targets are discussed in this review.

Development of ovalbumin implants with different spatial configurations for treatment of peripheral nerve injury

Peripheral nerve injury (PNI) seriously affects the health and life of patients, and is an urgent clinical problem that needs to be resolved. Nerve implants prepared from various biomaterials have played a positive role in PNI, but the effect should be further improved and thus new biomaterials is urgently needed. Ovalbumin (OVA) contains a variety of bioactive components, low immunogenicity, tolerance, antimicrobial activity, non-toxicity and biodegradability, and has the ability to promote wound healing, cell growth and antimicrobial properties. However, there are few studies on the application of OVA in neural tissue engineering. In this study, OVA implants with different spatial structures (membrane, fiber, and lyophilized scaffolds) were constructed by casting, electrospinning, and freeze-drying methods, respectively. The results showed that the OVA implants had excellent physicochemical properties and were biocompatible without significant toxicity, and can promote vascularization, show good histocompatibility, without excessive inflammatory response and immunogenicity. The in vitro results showed that OVA implants could promote the proliferation and migration of Schwann cells, while the in vivo results confirmed that OVA implants (the E5/70% and 20 kV 20 μL/min groups) could effectively regulate the growth of blood vessels, reduce the inflammatory response and promote the repair of subcutaneous nerve injury. Further on, the high-throughput sequencing results showed that the OVA implants up-regulated differential expression of genes related to biological processes such as tumor necrosis factor-α (TNF-α), phosphatidylinositide 3-kinases/protein kinase B (PI3K-Akt) signaling pathway, axon guidance, cellular adhesion junctions, and nerve regeneration in Schwann cells. The present study is expected to provide new design concepts and theoretical accumulation for the development of a new generation of nerve regeneration implantable biomaterials.

Octanol alleviates chronic constriction injury of sciatic nerve-induced peripheral neuropathy by regulating AKT/mTOR signaling

OBJECTIVE

Activation of gap junction channels can induce neuropathic pain. Octanol can limit the conductance of gap junctions containing connexin 43 proteins. Thus, this study focused on the roles of octanol in chronic constriction injury (CCI)-induced peripheral neuropathy in mice and its mechanisms of action.

METHODS

Male mice were assigned into control, sham, CCI, CCI + Octanol-20 mg/kg, CCI + Octanol-40 mg/kg and CCI + Octanol-80 mg/kg groups. CCI was performed by applying three loose ligations to mouse sciatic nerve, and the mice with CCI was administered with 20 mg/kg, 40 mg/kg, or 80 mg/kg octanol. The neuropathic pain development was examined by assessing thermal withdrawal latency, paw withdrawal mechanical threshold, and sciatic functional index. Histopathological changes were evaluated by hematoxylin and eosin staining. The phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR) was examined by western blotting. The expression of Akt and mTOR was also evaluated by immunofluorescence staining.

RESULTS

Octanol alleviated the CCI-induced mechanical and thermal hyperalgesia and sciatic functional loss. Additionally, octanol relieved the CCI-induced abnormal histopathological changes. Mechanistically, octanol inactivated the Akt/mTOR pathway in the mice with CCI.

CONCLUSION

In conclusion, octanol can alleviate CCI-induced peripheral neuropathic by regulating the Akt/mTOR pathway and might be a novel pharmacological intervention for neuropathic pain.

Surgical vs. Conservative Management of Chronic Sciatica (>3 Months) Due to Lumbar Disc Herniation: Systematic Review and Meta-Analysis

Sciatica, characterized by leg or back symptoms along the sciatic nerve pathway, often manifests as a chronic condition lasting over 12 weeks. Decision-making between nonoperative treatment and immediate microdiscectomy for chronic sciatica remains challenging, due to the complex relationship between symptom duration, severity, and lumbar discectomy outcomes. In this systematic review, we conducted a comprehensive search across Scopus, PubMed, Web of Science, and the Cochrane Library, identifying relevant two-arm clinical trials up to September 2023. Rigorous screening and data extraction were performed by two independent reviewers, with study quality evaluated using the risk of bias 2 (RoB) tool. This meta-analysis incorporated four studies comprising 352 participants. Our analysis revealed that conservative treatment was associated with a significant reduction in leg pain and improvement in, SF mental, and physical scores compared to surgical intervention. However surgical treatment demonstrated significant improvement in back pain. In conclusion, our findings suggest that surgical intervention may be more effective than non-surgical treatment for chronic sciatica-related back pain. Conservative treatment significantly reduces leg pain while improving mental and physical health outcomes. Ultimately, our findings support conservative as the initial approach unless surgery is warranted, particularly in cases with neurological deficits or cauda equina syndrome.

Neuronal Panx1 drives peripheral sensitization in experimental plantar inflammatory pain

BACKGROUND

The channel-forming protein Pannexin1 (Panx1) has been implicated in both human studies and animal models of chronic pain, but the underlying mechanisms remain incompletely understood.

METHODS

Wild-type (WT, n = 24), global Panx1 KO (n = 24), neuron-specific Panx1 KO (n = 20), and glia-specific Panx1 KO (n = 20) mice were used in this study at Albert Einstein College of Medicine. The von Frey test was used to quantify pain sensitivity in these mice following complete Freund's adjuvant (CFA) injection (7, 14, and 21 d). The qRT-PCR was employed to measure mRNA levels of Panx1, Panx2, Panx3, Cx43, Calhm1, and β-catenin. Laser scanning confocal microscopy imaging, Sholl analysis, and electrophysiology were utilized to evaluate the impact of Panx1 on neuronal excitability and morphology in Neuro2a and dorsal root ganglion neurons (DRGNs) in which Panx1 expression or function was manipulated. Ethidium bromide (EtBr) dye uptake assay and calcium imaging were employed to investigate the role of Panx1 in adenosine triphosphate (ATP) sensitivity. β-galactosidase (β-gal) staining was applied to determine the relative cellular expression levels of Panx1 in trigeminal ganglia (TG) and DRG of transgenic mice.

RESULTS

Global or neuron-specific Panx1 deletion markedly decreased pain thresholds after CFA stimuli (7, 14, and 21 d; P < 0.01 vs. WT group), indicating that Panx1 was positively correlated with pain sensitivity. In Neuro2a, global Panx1 deletion dramatically reduced neurite extension and inward currents compared to the WT group (P < 0.05), revealing that Panx1 enhanced neurogenesis and excitability. Similarly, global Panx1 deletion significantly suppressed Wnt/β-catenin dependent DRG neurogenesis following 5 d of nerve growth factor (NGF) treatment (P < 0.01 vs. WT group). Moreover, Panx1 channels enhanced DRG neuron response to ATP after CFA injection (P < 0.01 vs. Panx1 KO group). Furthermore, ATP release increased Ca2+ responses in DRGNs and satellite glial cells surrounding them following 7 d of CFA treatment (P < 0.01 vs. Panx1 KO group), suggesting that Panx1 in glia also impacts exaggerated neuronal excitability. Interestingly, neuron-specific Panx1 deletion was found to markedly reduce differentiation in cultured DRGNs, as evidenced by stunted neurite outgrowth (P < 0.05 vs. Panx1 KO group; P < 0.01 vs. WT group or GFAP-Cre group), blunted activation of Wnt/β-catenin signaling (P < 0.01 vs. WT, Panx1 KO and GFAP-Cre groups), and diminished cell excitability (P < 0.01 vs. GFAP-Cre group) and response to ATP stimulation (P < 0.01 vs. WT group). Analysis of β-gal staining showed that cellular expression levels of Panx1 in neurons are significantly higher (2.5-fold increase) in the DRG than in the TG.

CONCLUSIONS

The present study revealed that neuronal Panx1 is a prominent driver of peripheral sensitivity in the setting of inflammatory pain through cell-autonomous effects on neuronal excitability. This hyperexcitability dependence on neuronal Panx1 contrasts with inflammatory orofacial pain, where similar studies revealed a prominent role for glial Panx1. The apparent differences in Panx1 expression in neuronal and non-neuronal TG and DRG cells are likely responsible for the distinct impact of these cell types in the two pain models.

Endoplasmic reticular stress as an emerging therapeutic target for chronic pain: a narrative review

Chronic pain is a severely debilitating condition with enormous socioeconomic costs. Current treatment regimens with nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, or opioids have been largely unsatisfactory with uncertain benefits or severe long-term side effects. This is mainly because chronic pain has a multifactorial aetiology. Although conventional pain medications can alleviate pain by keeping several dysfunctional pathways under control, they can mask other underlying pathological causes, ultimately worsening nerve pathologies and pain outcome. Recent preclinical studies have shown that endoplasmic reticulum (ER) stress could be a central hub for triggering multiple molecular cascades involved in the development of chronic pain. Several ER stress inhibitors and unfolded protein response modulators, which have been tested in randomised clinical trials or apprpoved by the US Food and Drug Administration for other chronic diseases, significantly alleviated hyperalgesia in multiple preclinical pain models. Although the role of ER stress in neurodegenerative disorders, metabolic disorders, and cancer has been well established, research on ER stress and chronic pain is still in its infancy. Here, we critically analyse preclinical studies and explore how ER stress can mechanistically act as a central node to drive development and progression of chronic pain. We also discuss therapeutic prospects, benefits, and pitfalls of using ER stress inhibitors and unfolded protein response modulators for managing intractable chronic pain. In the future, targeting ER stress to impact multiple molecular networks might be an attractive therapeutic strategy against chronic pain refractory to steroids, NSAIDs, or opioids. This novel therapeutic strategy could provide solutions for the opioid crisis and public health challenge.

Maresins as novel anti-inflammatory actors and putative therapeutic targets in sepsis

Sepsis, a complex clinical syndrome characterized by an exaggerated host response to infection, often necessitates hospitalization and intensive care unit admission. Delayed or inaccurate diagnosis of sepsis, coupled with suboptimal treatment strategies, can result in unfavorable outcomes, including mortality. Maresins, a newly discovered family of lipid mediators synthesized from docosahexaenoic acid by macrophages, have emerged as key players in promoting inflammation resolution and the termination of inflammatory processes. Extensive evidence has unequivocally demonstrated the beneficial effects of maresins in modulating the inflammatory response associated with sepsis; however, their bioactivity and functions exhibit remarkable diversity and complexity. This article presents a comprehensive review of recent research on the role of maresins in sepsis, aiming to enhance our understanding of their effectiveness and elucidate the specific mechanisms underlying their actions in sepsis treatment. Furthermore, emerging insights into the management of patients with sepsis are also highlighted.

Optogenetic Activation of Peripheral Somatosensory Neurons in Transgenic Mice as a Neuropathic Pain Model for Assessing the Therapeutic Efficacy of Analgesics

Optogenetics is a novel biotechnology widely used to precisely manipulate a specific peripheral sensory neuron or neural circuit. However, the use of optogenetics to assess the therapeutic efficacy of analgesics is elusive. In this study, we generated a transgenic mouse stain in which all primary somatosensory neurons can be optogenetically activated to mimic neuronal hyperactivation in the neuropathic pain state for the assessment of analgesic effects of drugs. A transgenic mouse was generated using the advillin-Cre line mated with the Ai32 strain, in which channelrhodopsin-2 fused to enhanced yellow fluorescence protein (ChR2-EYFP) was conditionally expressed in all types of primary somatosensory neurons (advillincre/ChR2+/+). Immunofluorescence and transdermal photostimulation on the hindpaws were used to verify the transgenic mice. Optical stimulation to evoke pain-like paw withdrawal latency was used to assess the analgesic effects of a series of drugs. Injury- and pain-related molecular biomarkers were investigated with immunohistofluorescence. We found that the expression of ChR2-EYFP was observed in many primary afferents of paw skin and sciatic nerves and in primary sensory neurons and laminae I and II of the spinal dorsal horns in advillincre/ChR2+/+ mice. Transdermal blue light stimulation of the transgenic mouse hindpaw evoked nocifensive paw withdrawal behavior. Treatment with gabapentin, some channel blockers, and local anesthetics, but not opioids or COX-1/2 inhibitors, prolonged the paw withdrawal latency in the transgenic mice. The analgesic effect of gabapentin was also verified by the decreased expression of injury- and pain-related molecular biomarkers. These optogenetic mice provide a promising model for assessing the therapeutic efficacy of analgesics in neuropathic pain.

Leishmania mexicana promotes pain-reducing metabolomic reprogramming in cutaneous lesions

Cutaneous leishmaniasis (CL) is characterized by extensive skin lesions, which are usually painless despite being associated with extensive inflammation. The molecular mechanisms responsible for this analgesia have not been identified. Through untargeted metabolomics, we found enriched anti-nociceptive metabolic pathways in L. mexicana-infected mice. Purines were elevated in infected macrophages and at the lesion site during chronic infection. These purines have anti-inflammatory and analgesic properties by acting through adenosine receptors, inhibiting TRPV1 channels, and promoting IL-10 production. We also found arachidonic acid (AA) metabolism enriched in the ear lesions compared to the non-infected controls. AA is a metabolite of anandamide (AEA) and 2-arachidonoylglycerol (2-AG). These endocannabinoids act on cannabinoid receptors 1 and 2 and TRPV1 channels to exert anti-inflammatory and analgesic effects. Our study provides evidence of metabolic pathways upregulated during L. mexicana infection that may mediate anti-nociceptive effects experienced by CL patients and identifies macrophages as a source of these metabolites.

The identification of new roles for nicotinamide mononucleotide after spinal cord injury in mice: an RNA-seq and global gene expression study

Background

Nicotinamide mononucleotide (NMN), an important transforming precursor of nicotinamide adenine dinucleotide (NAD+). Numerous studies have confirmed the neuroprotective effects of NMN in nervous system diseases. However, its role in spinal cord injury (SCI) and the molecular mechanisms involved have yet to be fully elucidated.

Methods

We established a moderate-to-severe model of SCI by contusion (70 kdyn) using a spinal cord impactor. The drug was administered immediately after surgery, and mice were intraperitoneally injected with either NMN (500 mg NMN/kg body weight per day) or an equivalent volume of saline for seven days. The central area of the spinal cord was harvested seven days after injury for the systematic analysis of global gene expression by RNA Sequencing (RNA-seq) and finally validated using qRT-PCR.

Results

NMN supplementation restored NAD+ levels after SCI, promoted motor function recovery, and alleviated pain. This could potentially be associated with alterations in NAD+ dependent enzyme levels. RNA sequencing (RNA-seq) revealed that NMN can inhibit inflammation and potentially regulate signaling pathways, including interleukin-17 (IL-17), tumor necrosis factor (TNF), toll-like receptor, nod-like receptor, and chemokine signaling pathways. In addition, the construction of a protein-protein interaction (PPI) network and the screening of core genes showed that interleukin 1β (IL-1β), interferon regulatory factor 7 (IRF 7), C-X-C motif chemokine ligand 10 (Cxcl10), and other inflammationrelated factors, changed significantly after NMN treatment. qRT-PCR confirmed the inhibitory effect of NMN on inflammatory factors (IL-1β, TNF-α, IL-17A, IRF7) and chemokines (chemokine ligand 3, Cxcl10) in mice following SCI.

Conclusion

The reduction of NAD+ levels after SCI can be compensated by NMN supplementation, which can significantly restore motor function and relieve pain in a mouse model. RNA-seq and qRT-PCR systematically revealed that NMN affected inflammation-related signaling pathways, including the IL-17, TNF, Toll-like receptor, NOD-like receptor and chemokine signaling pathways, by down-regulating the expression of inflammatory factors and chemokines.

A Side-Effect-Free Interventional Therapy for Precisely Eliminating Unresectable Cancer Pain

Of patients bearing unresectable tumors at advanced stages, most undergo serious pain. For unresectable tumors adjacent to vital organs or nerves, eliminating local cancer pain without adverse effects remains a formidable challenge. Interventional ablative therapies (IATs), such as radio frequency ablation (RFA), microwave ablation, and irreversible electroporation, have been clinically adopted to treat various carcinomas. In this study, we established another palliative interventional therapy to eliminate local cancer pain, instead of relieving nociception temporarily. Here, we developed another interventional ablative therapy (termed nanoparticle-mediated microknife ablation) to locoregionally eliminate cancer pain and tumors. The IAT system was composed of self-assembled nanodrugs, infusion catheters, puncture needles, injection pump, and an empirical tumor ablation formula. Notably, the ablation formula established in the IAT system enables us to predict the essential nanoparticle (NP) numbers used for completely destroying tumors. In a mouse model of cancer pain, tumor-targeted nanodrugs made of Paclitaxel and Hematoporphyrin, which have an extremely high drug-loading efficiency (more than 60%), were infused into tumors through injection pumps under imaging guidance. In conclusion, when compared to classic chemotherapeutic agents, IAT showed significantly higher effectiveness in cancer pain removal. It also presented no damage to the nervous, sensory, and motor capabilities of the treated mice. All of these merits resulted from NPs' long-lasting retention, targeted ablation, and confined diffusion in tumor stroma. Therefore, this safe treatment modality has great potential to eradicate local cancer pain in the clinic.

Bell's palsy was associated with TRPV2 downregulation of Schwann cell by cold stress

OBJECTIVE

Epidemiological and clinical studies have shown that sharp changes in the ambient temperature are associated with the occurrence and development of Bell's palsy. However, the specific pathogenesis of peripheral facial paralysis remains nebulous. This study investigated the effect of cold stress on transient receptor potential cation channel subfamily V member 2 (TRPV2) secretion by Schwann cells and its role in Bell's palsy.

MATERIALS AND METHODS

Schwann cell morphology was observed using transmission electron microscopy (TEM). Cell proliferation, apoptosis and cell cycle were analysed using CCK8 and flow cytometry. ELISA, Reverse transcription-quantitative PCR, western blotting and immunocytochemical fluorescence staining were used to detect the effects of cold stress on TRPV2, neural cell adhesion molecule (NCAM) and nerve growth factor (NGF) expression in Schwann cells.

RESULTS

Cold stress resulted in a widening of the intercellular space, and the particles on the membrane showed different degrees of loss. Cold stress may cause Schwann cells to enter a cold dormant state. ELISA, RT-qPCR, western blotting and immunocytochemical fluorescences staining indicated that cold stress inhibited the expression of TRPV2, NCAM, and NGF.

CONCLUSIONS

Drastic temperature difference between cold and heat can downregulate TRPV2 and the secretome of Schwann cells. The imbalance of Schwann cell homeostasis under such stress may contribute to nerve signalling dysfunction leading to the development of facial paralysis.

Macrophages and microglia in inflammation and neuroinflammation underlying different pain states

Pain is a main symptom in inflammation, and inflammation induces pain via inflammatory mediators acting on nociceptive neurons. Macrophages and microglia are distinct cell types, representing immune cells and glial cells, respectively, but they share similar roles in pain regulation. Macrophages are key regulators of inflammation and pain. Macrophage polarization plays different roles in inducing and resolving pain. Notably, macrophage polarization and phagocytosis can be induced by specialized pro-resolution mediators (SPMs). SPMs also potently inhibit inflammatory and neuropathic pain via immunomodulation and neuromodulation. In this review, we discuss macrophage signaling involved in pain induction and resolution, as well as in maintaining physiological pain. Microglia are macrophage-like cells in the central nervous system (CNS) and drive neuroinflammation and pathological pain in various inflammatory and neurological disorders. Microglia-produced inflammatory cytokines can potently regulate excitatory and inhibitory synaptic transmission as neuromodulators. We also highlight sex differences in macrophage and microglial signaling in inflammatory and neuropathic pain. Thus, targeting macrophage and microglial signaling in distinct locations via pharmacological approaches, including immunotherapies, and non-pharmacological approaches will help to control chronic inflammation and chronic pain.

Maresin: Macrophage Mediator for Resolving Inflammation and Bridging Tissue Regeneration-A System-Based Preclinical Systematic Review

Maresins are lipid mediators derived from omega-3 fatty acids with anti-inflammatory and pro-resolving properties, capable of promoting tissue regeneration and potentially serving as a therapeutic agent for chronic inflammatory diseases. The aim of this review was to systematically investigate preclinical and clinical studies on maresin to inform translational research. Two independent reviewers performed comprehensive searches with the term "Maresin (NOT) Review" on PubMed. A total of 137 studies were included and categorized into 11 human organ systems. Data pertinent to clinical translation were specifically extracted, including delivery methods, optimal dose response, and specific functional efficacy. Maresins generally exhibit efficacy in treating inflammatory diseases, attenuating inflammation, protecting organs, and promoting tissue regeneration, mostly in rodent preclinical models. The nervous system has the highest number of original studies (n = 25), followed by the cardiovascular system, digestive system, and respiratory system, each having the second highest number of studies (n = 18) in the field. Most studies considered systemic delivery with an optimal dose response for mouse animal models ranging from 4 to 25 μg/kg or 2 to 200 ng via intraperitoneal or intravenous injection respectively, whereas human in vitro studies ranged between 1 and 10 nM. Although there has been no human interventional clinical trial yet, the levels of MaR1 in human tissue fluid can potentially serve as biomarkers, including salivary samples for predicting the occurrence of cardiovascular diseases and periodontal diseases; plasma and synovial fluid levels of MaR1 can be associated with treatment response and defining pathotypes of rheumatoid arthritis. Maresins exhibit great potency in resolving disease inflammation and bridging tissue regeneration in preclinical models, and future translational development is warranted.

The pro-resolving lipid mediator Maresin 1 ameliorates pain responses and neuroinflammation in the spared nerve injury-induced neuropathic pain: A study in male and female mice

Specialized pro-resolving mediators (SPMs) have recently emerged as promising therapeutic approaches for neuropathic pain (NP). We evaluated the effects of oral treatment with the SPM Maresin 1 (MaR1) on behavioral pain responses and spinal neuroinflammation in male and female C57BL/6J mice with spared nerve injury (SNI)-induced NP. MaR1, or vehicle, was administered once daily, on post-surgical days 3 to 5, by voluntary oral intake. Sensory-discriminative and affective-motivational components of pain were evaluated with von Frey and place escape/avoidance paradigm (PEAP) tests, respectively. Spinal microglial and astrocytic activation were assessed by immunofluorescence, and the spinal concentration of cytokines IL-1β, IL-6, IL-10, and macrophage colony-stimulating factor (M-CSF) were evaluated by multiplex immunoassay. MaR1 treatment reduced SNI-induced mechanical hypersensitivity on days 7 and 11 in both male and female mice, and appeared to ameliorate the affective component of pain in males on day 11. No definitive conclusions could be drawn about the impact of MaR1 on the affective-motivational aspects of pain in female mice, since repeated suprathreshold mechanical stimulation of the affected paw in the dark compartment did not increase the preference of vehicle-treated SNI females for the light side, during the PEAP test session (a fundamental assumption for PAEP's validity). MaR1 treatment also reduced ipsilateral spinal microglial and astrocytic activation in both sexes and marginally increased M-CSF in males, while not affecting cytokines IL-1β, IL-6 and IL-10 in either sex. In summary, our study has shown that oral treatment with MaR1 (i) produces antinociception even in an already installed peripheral NP mouse model, and (ii) this antinociception may extend for several days beyond the treatment time-frame. These therapeutic effects are associated with attenuated microglial and astrocytic activation in both sexes, and possibly involve modulation of M-CSF action in males.

Identification and validation of Rab11a in Rat orofacial inflammatory pain model induced by CFA

Orofacial pain (OFP) is a clinically very common and the most troubling condition; however, there is few effective way to relieve OFP. Rab11a, a small molecule guanosine triphosphate enzyme, is one of the Rab member family playing a vital role in intracellular endocytosis and the pain process. Therefore, we investigated the hub genes of rat OFP model induced by Complete Freund's Adjuvant (CFA) via re-analyzing microarray data (GSE111160). We found that Rab11a acted as a key hub gene in the process of OFP. During the validation of Rab11a, the OFP model was established by peripheral injection of CFA, which decreased the head withdrawal threshold (HWT) and head withdrawal lantency (HWL). Rab11a was observed in NeuN of Sp5C instead of GFAP/IBA-1, and double-IF of Rab11a and Fos positive cells were increased on the 7th day after CFA modeling statistically. Rab11a protein expression in TG and Sp5C of CFA group was also significantly increased. Interestingly, injection of Rab11a-targeted short hairpin RNA (Rab11a-shRNA) into Sp5C could reverse the decrease in HWT and HWL and reduce the expression level of Rab11a. Electrophysiological recording further demonstrated that the activity of Sp5C neuron was improved in CFA group, while Rab11a-shRNA considerably decreased the enhancement of Sp5C neuronal activity. Finally, we detected the expression level of p-PI3K, p-AKT, and p-mTOR in Sp5C of rats after injecting the Rab11a-shRNA virus. To our surprise, CFA upregulated the phosphorylation of PI3K, AKT and mTOR in Sp5C, and Rab11a-shRNA downregulated these molecules' expression. Our data suggest that CFA activates the PI3K/AKT signaling pathway through up-regulating Rab11a expression, which can induce OFP hyperalgesia development furtherly. Targeting Rab11a may be a novel treatment strategy for OFP.

Maresin1 ameliorates postoperative cognitive dysfunction in aged rats by potentially regulating the NF-κB pathway to inhibit astrocyte activation

Postoperative cognitive dysfunction (POCD) is one of the most serious postoperative complications in the elderly population. Perioperative central neuroinflammation is considered to be an important pathological mechanism of POCD, with the activation of astrocytes playing a key role in central neuroinflammation. Maresin1 (MaR1) is a specific pro-resolving mediator synthesized by macrophages in the resolution stage of inflammation, and provides unique anti-inflammatory and pro-resolution effects by limiting excessive neuroinflammation and promoting postoperative recovery. However, the question remains whether MaR1 can have a positive effect on POCD. The objective of this study was to investigate the protective effect of MaR1 on POCD cognitive function in aged rats after splenectomy. Morris water maze test and IntelliCage test showed that splenectomy could cause transient cognitive dysfunction in aged rats; however, the cognitive impairment of rats was significantly mitigated when MaR1 pretreatment was administered. MaR1 significantly alleviated the fluorescence intensity and protein expression of glial fibrillary acidic protein and central nervous system specific protein in the cornu ammonis 1 region of the hippocampus. Simultaneously, the morphology of astrocytes was also severely altered. Further experiments showed that MaR1 inhibited the mRNA and protein expression of several key proinflammatory cytokines-interleukin-1β, interleukin-6, and tumor necrosis factor-α in the hippocampus of aged rats following splenectomy. The molecular mechanism underlying this process was explored by evaluating expression of components of the nuclear factor κB (NF-κB) signaling pathway. MaR1 substantially inhibited the mRNA and protein expression of NF-κB p65 and κB inhibitor kinase β. Collectively, these results suggest that MaR1 ameliorated splenectomy-induced transient cognitive impairment in elderly rats, and this neuroprotective mechanism may occur through regulating the NF-κB pathway to inhibit astrocyte activation.

Ferulic acid alleviates sciatica by inhibiting neuroinflammation and promoting nerve repair via the TLR4/NF-κB pathway

INTRODUCTION

Sciatica causes intense pain. No satisfactory therapeutic drugs exist to treat sciatica. This study aimed to probe the potential mechanism of ferulic acid in sciatica treatment.

METHODS

Thirty-two SD rats were randomly divided into 4 groups: sham operation, chronic constriction injury (CCI), mecobalamin, and ferulic acid. We conducted RNA sequencing, behavioral tests, ELISA, PCR, western blotting, and immunofluorescence analysis. TAK-242 and JSH23 were administered to RSC96 and GMI-R1 cells to explore whether ferulic acid can inhibit apoptosis and alleviate inflammation.

RESULTS

RNA sequencing showed that TLR4/NF-κB pathway is involved in the mechanism of sciatica. CCI induced cold and mechanical hyperalgesia; destroyed the sciatic nerve structure; increased IL-1β, IL-6, TNF-α, IL-8, and TGF-β protein levels and IL-1β, IL-6, TNF-α, TGF-β, TLR4, and IBA-1 mRNA levels; and decreased IL-10 and INF-γ protein levels and IL-4 mRNA levels. Immunohistochemistry showed that IBA-1, CD32, IL-1β, iNOS, nNOS, COX2, and TLR4 expression was increased while S100β and Arg-1 decreased. CCI increased TLR4, IBA-1, IL-1β, iNOS, Myd88, p-NF-κB, and p-p38MAPK protein levels. Treatment with mecobalamin and ferulic acid reversed these trends. Lipopolysaccharide (LPS) induced RSC96 cell apoptosis by reducing Bcl-2 and Bcl-xl protein and mRNA levels and increasing Bax and Bad mRNA and IL-1β, TLR4, Myd88, p-NF-κB, and p-p38MAPK protein levels, while ferulic acid inhibited cell apoptosis by decreasing IL-1β, TLR4, Myd88, p-NF-κB, and p-p38MAPK levels and increasing Bcl-2 and Bcl-xl levels. In GMI-R1 cells, Ferulic acid attenuated LPS-induced M1 polarization by decreasing the M1 polarization markers IL-1β, IL-6, iNOS, and CD32 and increasing the M2 polarization markers CD206, IL-4, IL-10 and Arg-1. After LPS treatment, IL-1β, iNOS, TLR4, Myd88, p-p38MAPK, and p-NF-κB levels were obviously increased, and Arg-1 expression was reduced, while ferulic acid reversed these changes.

CONCLUSION

Ferulic acid can promote injured sciatic nerve repair by reducing neuronal cell apoptosis and inflammatory infiltration though the TLR4/NF-κB pathway.

Maresin1 Ameliorates Sepsis-Induced Microglial Neuritis Induced through Blocking TLR4-NF-κ B-NLRP3 Signaling Pathway

Objective: Neuroinflammation is a major etiology of cognitive dysfunction due to sepsis. Maresin1 (MaR1), identified as a docosahexaenoic acid (DHA)-derived metabolite from macrophages, has been demonstrated to exhibit potent neuroprotective and anti-inflammatory effects. Nevertheless, detailed functions and molecular mechanism of MaR1 in sepsis-induced cognitive dysfunction has not been fully elucidated. Here, we aimed to investigate potential neuroprotective effects of MaR1 on microglia-induced neuroinflammation in sepsis-induced cognitive impairment and to explore its anti-inflammatory mechanism. Methods: Different doses of MaR1 were administered to septic rats by via tail vein injection. The optimal dose was determined based on the 7-day survival rate of rats from each group. derived from macrophages with both anti-inflammatory to observe the ameliorative effects of MaR1 at optimal doses on cognitive dysfunction in septic rats. The effects of MaR1 on neuroinflammation-mediated microglial activation, neuronal apoptosis, and pro-inflammatory cytokine productions were in vivo and in vitro assayed, using Western blot, ELISA, TUNEL staining, Nissl staining, and the immunofluorescence method. To further elucidate anti-inflammatory machinery of MaR1, protein expressions of NLRP3 inflammatory vesicles and TLR4-NF-κB pathway-related proteins were subjected to Western blot assay. Results: After tail vein injection of MaR1 with different doses (2 ng/g, 4 ng/g, 8 ng/g), the results showed that 4 ng/g MaR1 treatment significantly increased the rats’ 7-day survival rate compared to the CLP controls. Therefore, subsequent experiments set 4 ng/g MaR1 as the optimal dose. Morris water maze experiments confirmed that MaR1 significantly reduced space memory dysfunction in rats. In addition, in CLP rats and LPS-stimulated BV2 microglia, MaR1 significantly reduced activated microglia and pro-inflammatory cytokines levels and neuronal apoptosis. Mechanically, MaR1 inhibits microglia-induced neuroinflammation through suppressing activations of NLRP3 inflammatory vesicles and TLR4-NF-κB signal pathway. Conclusion: Collectively, our findings suggested that MaR1 might be a prospective neuroprotective compound for prevention and treatment in the sepsis process.

Maresin1 can be a potential therapeutic target for nerve injury

Nerve injury significantly affects human motor and sensory function due to destruction of the integrity of nerve structure. In the wake of nerve injury, glial cells are activated, and synaptic integrity is destroyed, causing inflammation and pain hypersensitivity. Maresin1, an omega-3 fatty acid, is a derivative of docosahexaenoic acid. It has showed beneficial effects in several animal models of central and peripheral nerve injuries. In this review, we summarize the anti-inflammatory, neuroprotective and pain hypersensitivity effects of maresin1 in nerve injury and provide a theoretical basis for the clinical treatment of nerve injury using maresin1.

Specialized Pro-Resolving Mediators as Resolution Pharmacology for the Control of Pain and Itch

Specialized pro-resolving mediators (SPMs), including resolvins, protectins, and maresins, are endogenous lipid mediators that are synthesized from omega-3 polyunsaturated fatty acids during the acute phase or resolution phase of inflammation. Synthetic SPMs possess broad safety profiles and exhibit potent actions in resolving inflammation in preclinical models. Accumulating evidence in the past decade has demonstrated powerful analgesia of exogenous SPMs in rodent models of inflammatory, neuropathic, and cancer pain. Furthermore, endogenous SPMs are produced by sham surgery and neuromodulation (e.g., vagus nerve stimulation). SPMs produce their beneficial actions through multiple G protein-coupled receptors, expressed by immune cells, glial cells, and neurons. Notably, loss of SPM receptors impairs the resolution of pain. I also highlight the emerging role of SPMs in the control of itch. Pharmacological targeting of SPMs or SPM receptors has the potential to lead to novel therapeutics for pain and itch as emerging approaches in resolution pharmacology.

Frankincense-Myrrh treatment alleviates neuropathic pain via the inhibition of neuroglia activation mediated by the TLR4/MyD88 pathway and TRPV1 signaling

BACKGROUND

Neuroglia are important modulators of neuronal functionality, and thus play an integral role in the pathogenesis and treatment of neuropathic pain (NP). According to traditional Chinese medicine, Frankincense-Myrrh is capable of "activating blood and dissipating blood stasis", and as such these two biological compounds are commonly used to treat NP, however, the mechanisms underlying the efficacy of such treatment are unclear.

PURPOSE

This study aimed to further elucidate the protective effects associated with the Frankincense-Myrrh treatment of NP.

METHODS

A chronic sciatic nerve compression injury (CCI) model of NP was established, after which animals were gavaged with Frankincense, Myrrh, Frankincense-Myrrh, or the positive control drug pregabalin for 14 days. Network pharmacology approaches were used to identify putative pathways and targets associated with the Frankincense-Myrrh-mediated treatment of NP, after which these targets were subjected to in-depth analyses. The impact of TLR4 blockade on NP pathogenesis was assessed by intrathecally administering a TLR4 antagonist (LRU) or the MyD88 homodimerization inhibitory peptide (MIP).

RESULTS

Significant alleviation of thermal and mechanical hypersensitivity in response to Frankincense and Myrrh treatment was observed in NP model mice, while network pharmacology analyses suggested that the pathogenesis of NP may be related to TLR4/MyD88-mediated neuroinflammation. Consistently, Frankincense-Myrrh treatment was found to reduce TLR4, MyD88, and p-p65 expression in spinal dorsal horn neuroglia from treated animals, in addition to inhibiting neuronal TRPV1 and inflammatory factor expression. Intrathecal LRU and MIP delivery were sufficient to alleviate thermal and mechanical hyperalgesia in these CCI model mice, with concomitant reductions in neuronal TRPV1 expression and neuroglial activation in the spinal dorsal horn.

CONCLUSION

These data suggest that Frankincense-Myrrh treatment was sufficient to alleviate NP in part via inhibiting TLR4/MyD88 pathway and TRPV1 signaling activity. Blocking TLR4 and MyD88 activation may thus hold value as a means of treating NP.

Dulaglutide Improves Gliosis and Suppresses Apoptosis/Autophagy Through the PI3K/Akt/mTOR Signaling Pathway in Vascular Dementia Rats

Dulaglutide is a new type of hypoglycemic agent that agonizes glucagon-like peptide-1 receptor (GLP-1RA). It can be concluded from previous studies that a GLP-1RA can reduce apoptosis and regulate autophagy in the nervous system, while related research on dulaglutide in vascular dementia (VD) has not been reported. In our study, the VD rat model was established by bilateral carotid artery occlusion, and the results of the Morris water maze test (MWM) and open-field test showed that the application of dulaglutide could effectively reduce the cognitive decline of VD rats without changing the behavior in the open-field test, which was used to assess an anxiety-like phenotype. We applied HE staining and immunofluorescence labeling to show that dulaglutide treatment significantly alleviated neuronal damage in the hippocampal region of VD rats, and reduced microglial and astrocyte proliferation. Western blot results showed that dulaglutide reduced VD-induced neuronal apoptosis (BCL2/BAX, c-caspase3) and autophagy (P62, LC3B, Beclin-1), and upregulated phosphorylation of PI3K/Akt/mTOR signaling pathway. KEGG pathway analysis of RNA-Sequence results showed that the differentially expressed genes in the dulaglutide treatment group were significantly enriched in the mTOR signaling pathway, and the repressor of mTOR, Deptor, was down-regulated. In conclusion, this study suggested that dulaglutide may alleviate learning and memory impairment and neuron damage in VD rats by attenuating apoptosis, regulating autophagy, and activating the PI3K/Akt/mTOR signaling pathway in neurons, which may make it a promising candidate for the simultaneous treatment of VD and diabetes.

Comprehensive analysis of m6A methylation modification in chronic spinal cord injury in mice

Chronic spinal cord injury (CSCI) is a catastrophic disease of the central nervous system (CNS), resulting in partial or complete loss of neurological function. N6-methyladenosine (m6A) is the most common form of reversible posttranslational modification at the RNA level. However, the role of m6A modification in CSCI remains unknown. In this study, we established a CSCI model using a water-absorbable polyurethane polymer, with behavioral assessment, electrophysiological analysis, and histochemical staining for validation. Methylated RNA immunoprecipitation sequencing (meRIP-seq) and messenger RNA sequencing (mRNA-seq) were jointly explored to compare the differences between CSCI spinal tissue and normal spinal tissue. Furthermore, real-time quantitative reverse transcription pcr (qRT-PCR), western blot analysis, and immunofluorescence staining were used to analyze m6A modification-related proteins. We found that water-absorbable polyurethane polymer simulated well chronic spinal cord compression. Basso mouse scale scores and electrophysiological analysis showed continuous neurological function decline after chronic compression of the spinal cord. meRIP-seq identified 642 differentially modified m6A genes, among which 263 genes were downregulated and 379 genes were upregulated. mRNA-seq showed that 1544 genes were upregulated and 290 genes were downregulated after CSCI. Gene Ontology terms and enriched Kyoto Encyclopedia of Genes and Genomes pathways were also identified. qRT-PCR, western blotting, and immunofluorescence staining showed that Mettl14, Ythdf1, and Ythdf3 were significantly upregulated after CSCI. Our study revealed a comprehensive profile of m6A modifications in CSCI which may act as a valuable key for future research on CSCI.

Corydecumine G inhibits microglia activation via MAPK pathway in a rat model of neuropathic pain

BACKGROUND AND PURPOSE

Microglial activation plays an important role in the onset and progression of neuropathic pain by producing a variety of pro-inflammatory cytokines that interact with neurons to enhance neuronal hyperexcitability. Corydalis decumbens (Thunb.) pers., a traditional Chinese medicine has been used to treat mild cancer pain, dementia and to remit cerebral ischemia in clinics. Phenylphthalide isoquinolines are the major type of metabolites of C. decumbens and one of the derivatives, Corydecumine G (Cor G) has been shown to inhibit neuronal excitability. The present study aims to investigate the analgesic efficacy of Cor G in neuropathic pain rat model, the effects of Cor G on microglia activation and the possible mechanisms.

EXPERIMENTAL APPROACH

Neuropathic pain was modeled using chronic constriction sciatic nerve injury (CCI) in rats. Western blot, immunofluorescence, and qRT-PCR were used to evaluate the levels of protein and mRNA.

KEY RESULTS

Intraperitoneal administration of Cor G concentration-dependently ameliorates mechanical and thermo allodynia, suppresses CCI-induced p38/ERK phosphorylation and spinal cord microglia activation, and attenuates the expression levels of NO, inos, Tnf-α, Pge₂ in dorsal horn of L4-L6 spinal cord on the ligation side in CCI rats. Pretreatment with 30 μM Cor G decreased LPS-induced BV2 microglia activation, which occurred via the inos, Tnf-α, Il-1β, Il-6 and phospho-p38/ERK pathways.

CONCLUSIONS AND IMPLICATIONS

Taken together, we suggest that Cor G, the specific phthalide isoquinoline from traditional Chinese medicine Corydalis Decumbentis Rhizoma, may be promising for treatment of neuropathic pain.