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

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*

Neuropathic pain, often featuring allodynia, imposes significant physical and psychological burdens on patients, with limited treatments due to unclear central mechanisms. Addressing this challenge remains a crucial unsolved issue in pain medicine. Our previous study, using protein kinase C gamma (PKCγ)-tdTomato mice, highlights the spinal feedforward inhibitory circuit involving PKCγ neurons in gating neuropathic allodynia. However, the regulatory mechanisms governing this circuit necessitate further elucidation. We used diverse transgenic mice and advanced techniques to uncover the regulatory role of the descending serotonin (5-HT) facilitation system on spinal PKCγ neurons. Our findings revealed that 5-HT neurons from the rostral ventromedial medulla hyperpolarize spinal inhibitory interneurons via 5-HT_2C receptors, disinhibiting the feedforward inhibitory circuit involving PKCγ neurons and exacerbating allodynia. Inhibiting spinal 5-HT_2C receptors restored the feedforward inhibitory circuit, effectively preventing neuropathic allodynia. These insights offer promising therapeutic targets for neuropathic allodynia management, emphasizing the potential of spinal 5-HT_2C receptors as a novel avenue for intervention.
Animals ; Neuralgia/physiopathology* ; Protein Kinase C/metabolism* ; Receptor, Serotonin, 5-HT2C/metabolism* ; Hyperalgesia/physiopathology* ; Mice, Transgenic ; Mice ; Spinal Cord/metabolism* ; Serotonin/metabolism* ; Male ; Neurons/metabolism* ; Mice, Inbred C57BL

PURPOSE: The TWIK-related spinal cord K+ channel (TRESK) has recently been discovered and plays an important role in nociceptor excitability in the pain pathway. Because there have been no reports on the TRESK expression or its function in the dorsal horn of the spinal cord in neuropathic pain, we analyzed TRESK expression in the spinal dorsal horn in a spinal nerve ligation (SNL) model. MATERIALS AND METHODS: We established a SNL mouse model by using the L5-6 spinal nerves ligation. We used real-time polymerase chain reaction and immunohistochemistry to investigate TRESK expression in the dorsal horn and L5 dorsal rot ganglion (DRG). RESULTS: The SNL group showed significantly higher expression of TRESK in the ipsilateral dorsal horn under pain, but low expression in L5 DRG. Double immunofluorescence staining revealed that immunoreactivity of TRESK was mostly restricted in neuronal cells, and that synapse markers GAD67 and VGlut2 appeared to be associated with TRESK expression. We were unable to find a significant association between TRESK and calcineurin by double immunofluorescence. CONCLUSION: TRESK in spinal cord neurons may contribute to the development of neuropathic pain following injury.
Animals ; Disease Models, Animal ; Hyperalgesia ; Ligation ; Male ; Neuralgia/*metabolism/physiopathology ; Neurons/metabolism ; Nociceptors ; Pain/metabolism/*physiopathology ; Potassium Channels/*metabolism ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Spinal Cord Dorsal Horn/*metabolism ; Spinal Nerves/*injuries

OBJECTIVETo study the possible mechanisms of chronic nonbacterial prostatitis (CNP) pain.

METHODSCNP models were established in male Wistar rats by the autoimmune method. Then the paw withdrawal threshold (PWT) was detected using the Von Frey filament, prostate pathological examination was conducted, the expressions of substance P (SP) and transient receptor potential vanilloid 1 (TRPV1) in the prostate tissue and L5-S2 spinal segments were determined by immunohistochemistry and their correlations were analyzed.

RESULTSCompared with the control group, the CNP model rats showed markedly decreased PWT (P < 0.05) and obvious inflammation in the prostate tissue, with significant differences in the scope of lesion and interstitial lymphocyte infiltration (P < 0.05). The expressions of SP and TRPV1 in the prostate and spinal cord dorsal horn L5-S2 were remarkably upregulated in the models as compared with the control rats (P < 0.05). However, the expression of SP in the prostate was not correlated with that in the spinal cord (r = 0.099, P = 0.338), nor was that of TRPV1 (r = 0.000, P = 0.5).

CONCLUSIONSP and TRPV1 were involved in the formation and persistence of pain in CNP rats through their upregulated expressions in the L5-S2 spinal segments.

Animals ; Lumbosacral Region ; Male ; Neuralgia ; metabolism ; physiopathology ; Pain ; metabolism ; physiopathology ; Prostate ; metabolism ; Prostatitis ; metabolism ; physiopathology ; Rats ; Rats, Wistar ; Spinal Cord ; metabolism ; Substance P ; metabolism ; TRPV Cation Channels ; metabolism

Charcot-Marie-Tooth disease (CMT) is the most common inherited motor and sensory neuropathy. Previous studies have found that, according to CMT patients, neuropathic pain is an occasional symptom of CMT. However, neuropathic pain is not considered to be a significant symptom associated with CMT and, as a result, no studies have investigated the pathophysiology underlying neuropathic pain in this disorder. Thus, the first animal model of neuropathic pain was developed by our laboratory using an adenovirus vector system to study neuropathic pain in CMT. To this end, glycyl-tRNA synthetase (GARS) fusion proteins with a FLAG-tag (wild type [WT], L129P and G240R mutants) were expressed in spinal cord and dorsal root ganglion (DRG) neurons using adenovirus vectors. It is known that GARS mutants induce GARS axonopathies, including CMT type 2D (CMT2D) and distal spinal muscular atrophy type V (dSMA-V). Additionally, the morphological phenotypes of neuropathic pain in this animal model of GARS-induced pain were assessed using several possible markers of pain (Iba1, pERK1/2) or a marker of injured neurons (ATF3). These results suggest that this animal model of CMT using an adenovirus may provide information regarding CMT as well as a useful strategy for the treatment of neuropathic pain.
Animals ; Charcot-Marie-Tooth Disease/*diagnosis/*physiopathology ; *Disease Models, Animal ; Glycine-tRNA Ligase/*genetics/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Mutagenesis, Site-Directed ; Mutation/genetics ; Neuralgia/*diagnosis/*physiopathology

Charcot-Marie-Tooth disease (CMT) is the most common inherited motor and sensory neuropathy. Previous studies have found that, according to CMT patients, neuropathic pain is an occasional symptom of CMT. However, neuropathic pain is not considered to be a significant symptom associated with CMT and, as a result, no studies have investigated the pathophysiology underlying neuropathic pain in this disorder. Thus, the first animal model of neuropathic pain was developed by our laboratory using an adenovirus vector system to study neuropathic pain in CMT. To this end, glycyl-tRNA synthetase (GARS) fusion proteins with a FLAG-tag (wild type [WT], L129P and G240R mutants) were expressed in spinal cord and dorsal root ganglion (DRG) neurons using adenovirus vectors. It is known that GARS mutants induce GARS axonopathies, including CMT type 2D (CMT2D) and distal spinal muscular atrophy type V (dSMA-V). Additionally, the morphological phenotypes of neuropathic pain in this animal model of GARS-induced pain were assessed using several possible markers of pain (Iba1, pERK1/2) or a marker of injured neurons (ATF3). These results suggest that this animal model of CMT using an adenovirus may provide information regarding CMT as well as a useful strategy for the treatment of neuropathic pain.
Animals ; Charcot-Marie-Tooth Disease/*diagnosis/*physiopathology ; *Disease Models, Animal ; Glycine-tRNA Ligase/*genetics/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Mutagenesis, Site-Directed ; Mutation/genetics ; Neuralgia/*diagnosis/*physiopathology

OBJECTIVE: To investigate the effect of intrathecal sufentanil and protein kinase C inhibitor on pain threshold and the expression of N-methyl-D-aspartate receaptors (NMDAR)/calcitonin generelated peptide (CGRP) in spinal dorsal horn in rats with neuropathic pain. METHODS: Fifty-four healthy male Sprague-Dawley rats were randomly divided into 6 groups (9 in each group). The rats in the sham group(Group S) + spared nerve injury (SNI), SP+SNI, and P+SNI were intrathecally injected sufentanil (1 μg), sufentanil (1 μg) and chelerythrine chloride (11 μg), chelerythrine chloride (11 μg) followed by 10 μL normal saline once every day for 14 days postoperatively, respectively. Similarly, rats in the control group (Group C), the sham group (Group S), and SNI model group (Group SNI) were intrathecally injected 20 μL normal saline in the uniform interval. Pain behaviours were measured on Day 1 pre-surgery and on Day 1, 2, 7, and 14 after the intrathecal injection. The expressions of NMDAR and CGRP in the spinal dorsal horn of L5 segment were determined by immunohistochemistry on Day 2, 7, and 14 after the intrathecal injection. RESULTS: Compared with Group C and Group S, mechanical allodynia threshold in group SNI was decreased after the surgery (P<0.01), and expressions of NMDAR and CGRP immunoreactive soma in the spinal dorsal horn was significantly increased (P<0.01). Mechanical stimulation pain threshold was elevated in Group S+SNI, Group P+SNI, and Group SP+SNI compared with Group SNI (P<0.01), while expressions of NMDAR and CGRP immunoreactive soma in Group S+SNI, Group P +SNI, and Group SP+SNI were significantly decreased (P<0.05 or 0.01). CONCLUSION Intrathecal administration of sulfentanil and protein kinase C inhibitor can provide significant antinociception in rats with neuropathic pain and obviously inhibit the upregulation of NMDAR and CGRP expressions in the spinal dorsal horn of SNI rat models.
Animals ; Benzophenanthridines ; administration & dosage ; Calcitonin Gene-Related Peptide ; metabolism ; Injections, Spinal ; Male ; Neuralgia ; drug therapy ; metabolism ; physiopathology ; Pain Measurement ; Posterior Horn Cells ; metabolism ; Protein Kinase C ; antagonists & inhibitors ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Sufentanil ; administration & dosage

OBJECTIVETo investigate the changes of GABA-activated currents in isolated dorsal root ganglion neurons in rats with neuropathic pain.

METHODSThe neuropathic pain model was established by chronic constriction injury (CCI) 7 days before electrophysiological-recording. The rat DRG neurons were enzymatically dissociated. Whole-cell patch clamp technique was used to record GABA-activated currents. The changes of currents of injured side and opposite side were expected to compare with control group.

RESULTS(1) The currents of injured side of CCI group were notablely decreased compared with control group (GABA concentration, 0.1-1000 micromol/L). (2) By the contrast, opposite side currents of CCI group increased significantly compared with those in injured side and control group (GABA concentration, 0.01-1000 micromol/L).

CONCLUSIONThe data indicates that the chronic constriction injury change both the function of GABAA receptors of injury side and opposite side. The decrease of pre-synaptic inhibition of GABA may be the possible reason of neuropathic pain.

Animals ; Cell Separation ; Constriction ; Ganglia, Spinal ; pathology ; physiopathology ; Male ; Neuralgia ; etiology ; physiopathology ; Neurons ; metabolism ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-A ; metabolism ; physiology ; Sciatic Nerve ; injuries

Voltage-gated sodium channels are critical for the generation and conduction of nerve impulses. Recent studies show that in primary sensory neurons, the expression and dynamic regulation of several sodium channel subtypes play important roles in neuropathic pain. A number of SCN9A (encoding Nav1.7) gene point mutations are related with human genetic pain disorders. Transgenic and specific knockout techniques have revealed that Nav1.3, Nav1.8, Nav1.9 are important for the development and maintenance of neuropathic pain condition. Specific blockers of these sodium channels have been demonstrated to be effective in alleviating allodynia and hyperalgesia. Here we reviewed the roles of sodium channels in neuropathic pain, which may be applicable for the development of new drugs with enhanced efficacy for neuropathic pain treatment.
Animals ; Humans ; Neuralgia ; genetics ; metabolism ; physiopathology ; Neurons ; metabolism ; physiology ; Sodium Channels ; genetics ; metabolism ; physiology