Objective To explore the functional mechanism of spinal cord fragile X mental retardation protein(FMRP)involved in neuropathic pain(NP)by using the sciatic nerve model of chronic compression injury(CCI).Methods First,to investigate the changes of spinal cord FMRP and β-catenin following the development of NP,this study compared the 50%mechanical withdrawal threshold(MWT)and thermal withdrawal latency(TWL)in CCI rats,as well as changes of FMRP and β-catenin in the spinal dorsal horn post-surgery,through random grouping.Immunofluorescence staining was performed on spinal cord tissue sections from CCI rats.Second,to further validate the alterations in pain behavior when the FMRP function was lost,we measured the 50%MWT,TWL,and FMRP and β-catenin in the spinal dorsal horn after FMRP knockdown in CCI rats.Finally,we measured the 50%MWT,TWL,and FMRP and β-catenin in the case of FMRP hyperfunction for validation.Results Compared with the baseline CCI group and the naive and sham groups after modeling,the CCI group after modeling showed decreases in 50%MWT and TWL(all P<0.001).After modeling,compared with the naive group and the sham group,the CCI group presented up-regulated expression of FMRP(P=0.027,P=0.022)and β-catenin(P<0.001,P=0.001)in the spinal dorsal horn.No co-localization of FMRP with astrocytes and microglia was observed in the spinal cord,while the co-localization with neurons was observed.Compared with the baseline,the CCI+FMRP knockdown group showed decreases in 50%MWT(P=0.015)and TWL(P=0.001)after modeling.After intrathecal injection of small interfering RNA(siRNA),the 50%MWT(P=0.020)and TWL(P=0.009)of the CCI+FMRP knockdown group were increased.Moreover,compared with the CCI group and the CCI+solvent group,the CCI+FMRP knockdown group showed increases in 50%MWT(both P<0.001)and TWL(P=0.005,P=0.006).After intrathecal injection of siRNA,the expression levels of FMRP(P=0.012,P=0.007)and β-catenin(both P<0.001)in the spinal dorsal horn of the CCI+FMRP knockdown group were lower than those of the CCI group and the CCI+solvent group.Compared with the baseline FMRP overexpression group and the naive and negative control groups after adeno-associated virus(AAV)injection,the FMRP overexpression group after AAV injection showed decreases in 50%MWT and TWL(all P<0.001).After AAV injection,compared with the naive group and the negative control group,the FMRP overexpression group demonstrated up-regulated expression of FMRP(both P<0.001)and β-catenin(P=0.006,P=0.008)in the spinal cord.Conclusions This study confirms that spinal cord FMRP and β-catenin are involved in NP induced by CCI.Spinal cord FMRP may be one of the potential therapeutic targets for NP.
Animals ; beta Catenin/metabolism* ; Neuralgia/metabolism* ; Fragile X Mental Retardation Protein/physiology* ; Spinal Cord/metabolism* ; Rats ; Rats, Sprague-Dawley ; Male

OBJECTIVE: To observe the effects of point-moxibustion with Zhuang medicinal thread on differentially expressed genes (DEGs) in the dorsal root ganglion (DRG), tissue morphology, and the expression of Fc epsilon RI (FcεRI) pathway proteins spleen tyrosine kinase (Syk) and membrane spanning 4-domain A2 (MS4A2) in rat model of postherpetic neuralgia (PHN), and to explore the potential mechanism by which this therapy alleviates pain sensitization. METHODS: Thirty-nine male Sprague-Dawley (SD) rats were randomly divided into a control group, a model group, and a moxibustion group, with 13 rats in each group. The PHN model was established in the model and moxibustion groups by intraperitoneal injection of resiniferatoxin. In the moxibustion group, bilateral L₄-L₆ "Jiaji" (EX-B2) points were treated with point-moxibustion with Zhuang medicinal thread from day 7 post-modeling, with two cones per acupoint per session, every other day for a total of 10 sessions. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured at 1 day before modeling and on days 1, 4, 7, 13, 19, and 25 after modeling. After intervention, HE staining was used to observe DRG morphology. RNA sequencing was performed to analyze DEGs in DRG and conduct bioinformatics analysis. The expression of Syk and MS4A2 mRNA and proteins in the FcεRI pathway in DRG was detected by quantitative PCR and Western blot. RESULTS: Compared with the control group, the model group exhibited decreased MWT (P<0.05) and increased TWL (P<0.05); histopathological analysis revealed neuronal atrophy, nuclear displacement, and intracellular vacuoles, with a slightly loose arrangement; the RNA-Seq identified 3,207 DEGs (1,997 upregulated and 1,210 downregulated); the mRNA and protein expression levels of Syk and MS4A2 were significantly increased (P<0.01). Compared with the model group, the moxibustion group showed increased MWT (P<0.05) and decreased TWL (P<0.05), with relatively normal neuronal morphology; the RNA-Seq identified 426 DEGs (250 upregulated and 176 downregulated); the mRNA and protein expression levels of Syk and MS4A2 were significantly decreased (P<0.05). Venn diagram analysis identified 156 DEGs that showed a reversal in expression trends after treatment, including Syk and MS4A2, which are associated with pain sensitization. KEGG pathway analysis indicated that these DEGs were primarily enriched in the FcεRI pathway. CONCLUSION Point-moxibustion with Zhuang medicinal thread could alleviate pain sensitization in PHN rats, possibly by inhibiting the FcεRI signaling pathway and downregulating the expression of Syk and MS4A2.
Animals ; Rats, Sprague-Dawley ; Male ; Rats ; Moxibustion ; Neuralgia, Postherpetic/physiopathology* ; Syk Kinase/metabolism* ; Acupuncture Points ; Humans ; Ganglia, Spinal/metabolism* ; Signal Transduction

OBJECTIVE: To observe the clinical efficacy of chicken-claw needling with blade needle for postherpetic neuralgia (PHN). METHODS: A total of 30 patients with PHN were treated with chicken-claw needling with blade needle, the most painful area, costal angle on the same side with the affected intercostal nerve and the midpoint of the line connecting the first two points along the intercostal nerve were selected as treatment points, without needle retained, once a week, a total of 2 times were required. Before and after treatment, the scores of pain visual analogue scale (VAS) and dermatology life quality index (DLQI) were observed, and the clinical efficacy was evaluated after treatment. The recurrence rate of neuralgia was evaluated on the 60th day after treatment. RESULTS: After treatment, the scores of VAS and DLQI were decreased compared with those before treatment (P<0.05). Of 30 patients, 4 cases were cured, 20 cases showed markedly efficacy, 4 cases were improved, 2 cases were ineffective, the total effective rate was 93.3% (28/30). The recurrence rate of neuralgia was 6.7% (2/30). CONCLUSION Chicken-claw needling with blade needle could effectively relieve the pain in patients with PHN, improve the quality of life and reduce the recurrence rate of neuralgia.
Humans ; Male ; Female ; Neuralgia, Postherpetic/therapy* ; Middle Aged ; Aged ; Acupuncture Therapy/methods* ; Acupuncture Points ; Treatment Outcome ; Needles ; Adult

The paper introduces Professor LIU Xing's clinical experience and characteristics of integrative acupuncture and medication in treatment of primary trigeminal neuralgia (PTN). It is believed that the essential pathogenesis of PTN is pathogenic wind, and qi and blood obstruction results from invasion of pathogenic wind. Hence, dispelling wind is the key principle of treatment. Palpation is done at first in the neck, face and buccal mucosal region to detect the masses in treatment. Acupotomy is operated at the masses distributed at Shangguan (GB3), Xiaguan (ST7) and the white line of buccal mucosa, so as to release masses. Additionally, five-wind points (Fengfu [GV16], bilateral Fengchi [GB20], Yifeng [TE17], Bingfeng [SI12] and Fengmen [BL12]), three-nape points (bilateral Naokong [GB19], Tianzhu [BL10] and Jianjing [GB21]) and three-governor-vessel points (Baihui [GV20], Zhiyang [GV9] and Yintang [GV24⁺]) are selected to dispel wind and stop pain. Besides, herbal decoction (wu feng tang) and blood-letting at ear apex are administered in combination. The integration of acupuncture and medication obtains a holistic effect on PTN by dispelling wind pathogen, and promoting qi and blood circulation.
Humans ; Trigeminal Neuralgia/drug therapy* ; Acupuncture Therapy ; Acupuncture Points ; Female ; Male ; Middle Aged ; Drugs, Chinese Herbal/administration & dosage* ; Combined Modality Therapy ; Adult ; Aged

Endothelin-1 is a peptide derived from endothelial cells, consisting of 21 amino acid residues. In recent years, research has found that endothelin-1 not only plays a key role in vascular tone regulation but also participates in the occurrence and development of various types of pathological pain, including inflammatory pain, neuropathic pain, and cancer pain. Endothelin-1 binds to its receptors and activates multiple signaling pathways such as protein kinase C, calcium ion channels, and the phosphoinositide pathway, thereby influencing neuronal excitability and nociceptive information transmission. This article briefly reviews the current understanding of the mechanisms and potential roles of endothelin-1 in the development of pain, as well as commonly used endothelin-1 receptor antagonists, aiming to provide clues for better utilizing endothelin-1 and its receptors to alleviate and treat pathological pain.
Humans ; Endothelin-1/physiology* ; Pain/physiopathology* ; Signal Transduction/physiology* ; Animals ; Neuralgia/physiopathology* ; Cancer Pain/physiopathology* ; Endothelin Receptor Antagonists

Central sensitization(CS) is an important factor in inducing neuropathic pain(NPP), and the association between signal transduction protein 1(Epac1) and piezoelectric type mechanosensitive ion channel component 2(Piezo2) is a new and significant pathway for initiating CS. This study whether the central analgesic effect of Maxiong Powder is achieved through the synchronized regulation of the Epac1-Piezo2 signaling pathway in the medial habenular nucleus(MHb) and interpeduncular nucleus(IPN) of the brain. Dynamic in vivo microdialysis, combined with high-performance liquid chromatography-fluorescence detection(HPLC-RFC), behavioral assessments, immunohistochemistry, Western blot, and quantitative reverse transcription PCR, were employed in rats with partial sciatic nerve injury(SNI) to investigate the distribution and expression of Epac1 and Piezo2 proteins and genes in the MHb and IPN regions, and the changes in the extracellular levels of glutamate(Glu), aspartic acid(Asp), and glycine(Gly). Compared with the sham group, rats in the SNI group showed significantly reduced analgesic activity, a significant increase in cold pain sensitivity scores, and elevated Glu levels in the MHb and IPN regions. Additionally, the number of Piezo2-positive cells in these regions, as well as the expression levels of Epac1 and Piezo2 proteins and genes, were significantly increased. Compared with the SNI group, after Maxiong Powder administration, the analgesic activity in rats significantly increased, and cold pain sensitivity scores were significantly reduced. Maxiong Powder also significantly decreased the Glu content in the MHb and IPN regions and the Gly content in the MHb region, while significantly increasing the Asp content in both regions. Furthermore, Maxiong Powder significantly reduced the number of Piezo2-positive cells and lowered the protein and gene expression levels of Epac1 and Piezo2 in both brain regions. The central analgesic effect of Maxiong Powder may be related to its inhibition of Glu and Gly release in the extracellular fluid of the MHb and IPN regions, the increase of Asp levels in these regions, and the regulation of the Epac1-Piezo2 pathway through the reduction of Epac1 and Piezo2 protein and gene expression. These results provide partial scientific evidence for the clinical analgesic efficacy of Maxiong Powder and offer new ideas and approaches for the clinical treatment of NPP.
Animals ; Neuralgia/genetics* ; Rats ; Signal Transduction/drug effects* ; Male ; Rats, Sprague-Dawley ; Guanine Nucleotide Exchange Factors/genetics* ; Drugs, Chinese Herbal/administration & dosage* ; Habenula/drug effects* ; Ion Channels/genetics* ; Humans

BACKGROUND: Postherpetic neuralgia (PHN) is the most common complication of herpes zoster infection and affects patients' quality of life. Acupuncture therapy is regarded as a competitive method of treatment for analgesia. OBJECTIVE: To summarize evidence from systematic reviews (SRs) and evaluate the effectiveness and safety of different acupuncture therapies for treating PHN. METHODS: Eight electronic databases were searched from their inception to August 5, 2022, including 4 international electronic databases (PubMed, EMBASE, the Cochrane Library, and Web of Science) and 4 Chinese databases (Chinese Biomedical Database, China National Knowledge Infrastructure, VIP Database and Wanfang Database). Methodological quality was assessed by A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2). The Risk of Bias in Systematic Review (ROBIS) tool was used to assess the risk of bias in SRs. Evidence level was assessed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: Totally, 7 SRs were included, including 128 studies and 9,792 patients. In AMSTAR 2, most of the SRs were of low or critically low levels since they had more than 1 critical deficiency. In ROBIS, 1 SR (14.29%) was rated as high risk, and the other 6 (85.71%) were rated as low risk. In the GRADE system, 9 outcomes (28.13%) were valued as high level, 5 (15.63%) as moderate level, 1 (3.13%) as low, and 17 (53.13%) as very low. In the effectiveness of acupuncture therapy, the group "moxibustion vs. original medical treatment" [mean difference (MD)=-1.44, 95% confidence interval (CI): -1.80 to -1.08, I²=99%, P<0.00001] was of the highest heterogeneity and the group "bloodletting vs. original medical treatment" (MD=-2.80, 95% CI: -3.14 to -2.46, I²=0, P<0.00001) was of the lowest heterogeneity. Six SRs have reported the safety of their studies and no serious events were shown in the treatment and control groups. CONCLUSIONS Acupuncture therapy seems to be effective in treating PHN. Despite the evidence that suggested the advantages of acupuncture therapy in relieving pain and promoting efficacy and safety, the methodological quality was quite low. Further studies should pay more attention to the quality of original studies and evidence for SRs to confirm these findings. (PROSPERO registration No. CRD42022344790).
Humans ; Neuralgia, Postherpetic/therapy* ; Acupuncture Therapy/methods* ; Systematic Reviews as Topic

OBJECTIVE: To illustrate the role of dehydrocorydaline (DHC) in chronic constriction injury (CCI)-induced neuropathic pain and the underlying mechanism. METHODS: C57BL/6J mice were randomly divided into 3 groups by using a random number table, including sham group (sham operation), CCI group [intrathecal injection of 10% dimethyl sulfoxide (DMSO)], and CCI+DHC group (intrathecal injection of DHC), 8 mice in each group. A CCI mouse model was conducted to induce neuropathic pain through ligating the right common sciatic nerve. On day 14 after CCI modeling or sham operation, mice were intrathecal injected with 5 µL of 10% DMSO or 10 mg/kg DHC (5 µL) into the 5th to 6th lumbar intervertebral space (L5-L6). Pregnant ICR mice were sacrificed for isolating primary spinal neurons on day 14 of embryo development for in vitro experiment. Pain behaviors were evaluated by measuring the paw withdrawal mechanical threshold (PWMT) of mice. Immunofluorescence was used to observe the activation of astrocytes and microglia in mouse spinal cord. Protein expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), phosphorylation of N-methyl-D-aspartate receptor subunit 2B (p-NR2B), and NR2B in the spinal cord or primary spinal neurons were detected by Western blot. RESULTS: In CCI-induced neuropathic pain model, mice presented significantly decreased PWMT, activation of glial cells, overexpressions of iNOS, TNF-α, IL-6, and higher p-NR2B/NR2B ratio in the spinal cord (P<0.05 or P<0.01), which were all reversed by a single intrathecal injection of DHC (P<0.05 or P<0.01). The p-NR2B/NR2B ratio in primary spinal neurons were also inhibited after DHC treatment (P<0.05). CONCLUSION An intrathecal injection of DHC relieved CCI-induced neuropathic pain in mice by inhibiting the neuroinflammation and neuron hyperactivity.
Animals ; Neuralgia/etiology* ; Mice, Inbred C57BL ; Analgesics/pharmacology* ; Neuroinflammatory Diseases/pathology* ; Constriction ; Male ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Nitric Oxide Synthase Type II/metabolism* ; Mice, Inbred ICR ; Microglia/pathology* ; Spinal Cord/drug effects* ; Female ; Mice ; Tumor Necrosis Factor-alpha/metabolism* ; Disease Models, Animal ; Constriction, Pathologic/complications* ; Interleukin-6/metabolism* ; Astrocytes/metabolism* ; Chronic Disease ; Neurons/metabolism*

OBJECTIVES: Neuropathic pain (NP) is one of the most common forms of chronic pain, yet current treatment options are limited in effectiveness. Peripheral nerve injury activates spinal microglia, altering their inflammatory response and phagocytic functions, which contributes to the progression of NP. Most current research on NP focuses on microglial inflammation, with relatively little attention to their phagocytic function. Early growth response factor 2 (EGR2) has been shown to regulate microglial phagocytosis, but its specific role in NP remains unclear. This study aims to investigate how EGR2 modulates microglial phagocytosis and its involvement in NP, with the goal of identifying potential therapeutic targets. METHODS: Adult male Sprague-Dawley (SD) rats were used to establish a chronic constriction injury (CCI) model of the sciatic nerve. Pain behaviors were assessed on days 1, 3, 7, 10, and 14 post-surgery to confirm successful model induction. The temporal and spatial expression of EGR2 in the spinal cord was examined using real-time quantitative PCR (RT-qPCR), Western blotting, and immunofluorescence staining. Adeno-associated virus (AAV) was used to overexpress EGR2 in the spinal cord, and behavioral assessments were performed to evaluate the effects of EGR2 modulation of NP. CCI and lipopolysaccharide (LPS) models were established in animals and microglial cell lines, respectively, and changes in phagocytic activity were measured using RT-qPCR and fluorescent latex bead uptake assays. After confirming the involvement of microglial phagocytosis in NP, AAV was used to overexpress EGR2 in both in vivo and in vitro models, and phagocytic activity was further evaluated. Finally, eukaryotic transcriptome sequencing was conducted to screen differentially expressed mRNAs, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses to identify potential downstream effectors of EGR2. RESULTS: The CCI model successfully induced NP. Following CCI, EGR2 expression in the spinal cord was upregulated in parallel with NP development. Overexpression of EGR2 via spinal AAV injection enhanced microglial phagocytic activity and increased pain hypersensitivity in rats. Both animal and cellular models showed that CCI or LPS stimulation enhanced microglial phagocytosis, which was further amplified by EGR2 overexpression. Transcriptomic analysis of spinal cord tissues from CCI rats overexpressing EGR2 revealed upregulation of numerous genes associated with microglial phagocytosis and pain regulation. Among them, Lag3 emerged as a potential downstream target of EGR2. CONCLUSIONS EGR2 contributes to the maintenance of NP by enhancing microglial phagocytosis in the spinal dorsal horn.
Animals ; Microglia/metabolism* ; Phagocytosis/physiology* ; Rats, Sprague-Dawley ; Neuralgia/physiopathology* ; Early Growth Response Protein 2/metabolism* ; Male ; Rats ; Spinal Cord/metabolism* ; Sciatic Nerve/injuries*

OBJECTIVES: Pain sensitization, as a core feature of neuropathic pain (NP), is closely associated with inflammatory imbalance within the central nervous system. To investigate the effects of intrathecal injection of noggin (NOG) on mechanical hypersensitivity, microglial (MG) activation and polarization, and iron metabolism in a spinal nerve ligation (SNL)-induced rat model of NP, and to explore the role of signal transducer and activator of transcription 3 (STAT3) in MG phenotypic transformation. METHODS: Sixty-six Sprague-Dawley (SD) rats were randomly divided into 3 groups: Sham, SNL, and SNL+NOG. Paw withdrawal threshold (PWT) was assessed using von Frey filaments. Western blotting and real-time polymerase chain reaction (RT-PCR) were used to detect spinal cord expression of MG activation marker CD11b, STAT3, phosphorylated STAT3 (p-STAT3), M1 polarization markers [CD86, CD32, interleukin (IL)-1β], tumor necrosis factor-alpha (TNF-α), and CC chemokine receptor 2 (CCR2), M2 markers [CD204, CD163, CX3C chemokine receptor 1 (CX3CR1), IL-10, and arginase-1 (ARG-1)], and iron metabolism-related proteins including ferroportin (FPN, gene: SLC40A1), hepcidin (gene: HAMP), transferrin receptor (gene: TFRC), and divalent metal transporter 1 (DMT-1, gene: SLC11A2). p-STAT3 localization in MGs was visualized via immunofluorescence. In vitro, primary MGs were divided into Control, bone morphogenetic protein-4 (BMP4), and BMP4+Stattic (STAT3 inhibitor) groups to examine the effects of STAT3 inhibition on MG activation, polarization, and iron regulation. RESULTS: In vivo, compared with the Sham group, the SNL and SNL+NOG groups exhibited significantly decreased PWT (P<0.05), elevated spinal CD11b and p-STAT3 protein levels (all P<0.05), increased M1 markers (CD86, CD32, IL-1β, TNF-α, and CCR2) (all P<0.05), and decreased M2 markers (CD204 protein; mRNA of CD204, ARG-1) (all P<0.05). Hepcidin protein and mRNA levels of HAMP, SLC11A2, and TFRC were significantly elevated, while FPN protein and SLC40A1 mRNA were reduced (all P<0.05). Compared to SNL alone, the SNL+NOG group showed increased PWT, decreased CD11b, p-STAT3, and M1 marker expression (except TNF-α), increased M2 marker expression, reduced hepcidin and HAMP levels, and increased FPN and SLC40A1 expression (all P<0.05). In vitro, BMP4 treatment increased CD11b, STAT3, p-STAT3, CD86, and hepcidin levels, while reducing CD204 and FPN (all P<0.05). Inhibition STAT3 with Stattic reversed these changes (all P<0.05). CONCLUSIONS NOG alleviates SNL-induced NP by antagonizing the STAT3 signaling pathway, thereby rebalancing microglial polarization and restoring iron metabolism.
Animals ; Neuralgia/drug therapy* ; Rats, Sprague-Dawley ; Microglia/cytology* ; STAT3 Transcription Factor/metabolism* ; Rats ; Iron/metabolism* ; Male ; Signal Transduction/drug effects* ; Carrier Proteins/therapeutic use* ; Homeostasis/drug effects* ; Spinal Cord/metabolism*