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

Neuropathic pain, a debilitating condition caused by dysfunction of the somatosensory nervous system, remains difficult to treat due to limited understanding of its molecular mechanisms. Bioinformatics analysis identified cerebellin 2 (CBLN2) as highly enriched in human and murine proprioceptive and nociceptive neurons. We found that CBLN2 expression is persistently upregulated in dorsal root ganglia (DRG) following spinal nerve ligation (SNL) in mice. In addition, transcription factor SOX11 binds to 12 cis-regulatory elements within the Cbln2 promoter to enhance its transcription. SNL also induced SOX11 upregulation, with SOX11 and CBLN2 co-localized in nociceptive neurons. The siRNA-mediated knockdown of Sox11 or Cbln2 attenuated SNL-induced mechanical allodynia and thermal hyperalgesia. High-throughput sequencing of DRG following intrathecal injection of CBLN2 revealed widespread gene expression changes, including upregulation of numerous NF-κB downstream targets. Consistently, CBLN2 activated NF-κB signaling, and inhibition with pyrrolidine dithiocarbamate reduced CBLN2-induced pain hypersensitivity, proinflammatory cytokines and chemokines production, and neuronal hyperexcitability. Together, these findings identified the SOX11/CBLN2/NF-κB axis as a critical mediator of neuropathic pain and a promising target for therapeutic intervention.
Animals ; Neuralgia/metabolism* ; Ganglia, Spinal/metabolism* ; Up-Regulation ; Mice ; NF-kappa B/metabolism* ; SOXC Transcription Factors/genetics* ; Male ; Neuroinflammatory Diseases/metabolism* ; Mice, Inbred C57BL ; Nerve Tissue Proteins/genetics* ; Hyperalgesia/metabolism* ; Signal Transduction ; Spinal Nerves

Effective axon regeneration is essential for the successful restoration of nerve functions in patients suffering from axon injury-associated neurological diseases. Certain self-regeneration occurs in injured peripheral axonal branches of dorsal root ganglion (DRG) neurons but does not occur in their central axonal branches. By performing rat sciatic nerve or dorsal root axotomy, we determined the expression of the dysbindin domain containing 2 (DBNDD2) in the DRGs after the regenerative peripheral axon injury or the non-regenerative central axon injury, respectively, and found that DBNDD2 is down-regulated in the DRGs after peripheral axon injury but up-regulated after central axon injury. Furthermore, we found that DBNDD2 expression differs in neonatal and adult rat DRGs and is gradually increased during development. Functional analysis through DBNDD2 knockdown revealed that silencing DBNDD2 promotes the outgrowth of neurites in both neonatal and adult rat DRG neurons and stimulates robust axon regeneration in adult rats after sciatic nerve crush injury. Bioinformatic analysis data showed that transcription factor estrogen receptor 1 (ESR1) interacts with DBNDD2, exhibits a similar expression trend as DBNDD2 after axon injury, and may targets DBDNN2. These studies indicate that reduced level of DBNDD2 after peripheral axon injury and low abundance of DBNDD2 in neonates contribute to axon regeneration and thus suggest the manipulation of DBNDD2 expression as a promising therapeutic approach for improving recovery after axon damage.
Animals ; Ganglia, Spinal/metabolism* ; Nerve Regeneration/genetics* ; Rats ; Axons/metabolism* ; Sciatic Nerve/injuries* ; Rats, Sprague-Dawley ; Male

Cancer pain is one of the most common symptoms in patients with advanced cancer. In this study, we aimed to investigate the effects of the Mas-related gene C (MrgC) receptors on bone cancer pain. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured after the inoculation of Walker 256 mammary gland carcinoma cells into the tibia of adult Sprague-Dawley rats. The effects of MrgC receptor agonist bovine adrenal medulla 8-22 (BAM8-22) on nociceptive behaviors were investigated after intrathecal injection on days 16 and 17. Glial fibrillary acidic protein (GFAP)-positive cells in the spinal dorsal cord, and calcitonin gene related peptide (CGRP)-, neuronal nitric oxide synthase (nNOS)- and IL-1β-positive neurons in the dorsal root ganglia (DRG) were examined by immunofluorescence staining. The expression of nNOS and IL-1β proteins in the spinal dorsal horn and the DRG was examined by Western blotting after treatment with (Tyr6)-γ2-MSH-6-12 (MSH), which was another MrgC receptor agonist. The results showed that intrathecal injection of BAM8-22 (30 nmol) attenuated mechanical allodynia in a rat model of bone cancer pain and the effects could last for about 60 min, and single administration of BAM8-22 for two consecutive days reduced mechanical allodynia by about half on the third day. Moreover, the number of GFAP-positive cells in the spinal dorsal horn, and the number of CGRP-, nNOS- and IL-1β-positive neurons in the DRG were decreased. Similarly, intrathecal administration of MSH (15 nmol) reduced the expression of nNOS and IL-1β in the spinal dorsal horn and the DRG. In conclusion, activation of MrgC receptors suppresses the activation of astrocytes in the spinal dorsal cord and the expression of CGRP, nNOS, and IL-1β in the spinal dorsal cord and/or DRG, which may underlie the inhibition of bone cancer pain. These findings provide a novel strategy for the treatment of bone cancer pain.
Animals ; Cancer Pain/drug therapy* ; Rats ; Rats, Sprague-Dawley ; Bone Neoplasms/complications* ; Ganglia, Spinal/metabolism* ; Spinal Cord Dorsal Horn/metabolism* ; Receptors, G-Protein-Coupled/genetics* ; Female ; Calcitonin Gene-Related Peptide/genetics* ; Interleukin-1beta/metabolism* ; Peptide Fragments/metabolism* ; Nitric Oxide Synthase Type I/genetics* ; Disease Models, Animal

Post-amputation pain causes great suffering to amputees, but still no effective drugs are available due to its elusive mechanisms. Our previous clinical studies found that surgical removal or radiofrequency treatment of the neuroma at the axotomized nerve stump effectively relieves the phantom pain afflicting patients after amputation. This indicated an essential role of the residual nerve stump in the formation of chronic post-amputation pain (CPAP). However, the molecular mechanism by which the residual nerve stump or neuroma is involved and regulates CPAP is still a mystery. In this study, we found that nociceptors expressed the mechanosensitive ion channel TMEM63A and macrophages infiltrated into the dorsal root ganglion (DRG) neurons worked synergistically to promote CPAP. Histology and qRT-PCR showed that TMEM63A was mainly expressed in mechanical pain-producing non-peptidergic nociceptors in the DRG, and the expression of TMEM63A increased significantly both in the neuroma from amputated patients and the DRG in a mouse model of tibial nerve transfer (TNT). Behavioral tests showed that the mechanical, heat, and cold sensitivity were not affected in the Tmem63a^-/- mice in the naïve state, suggesting the basal pain was not affected. In the inflammatory and post-amputation state, the mechanical allodynia but not the heat hyperalgesia or cold allodynia was significantly decreased in Tmem63a^-/- mice. Further study showed that there was severe neuronal injury and macrophage infiltration in the DRG, tibial nerve, residual stump, and the neuroma-like structure of the TNT mouse model, Consistent with this, expression of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β all increased dramatically in the DRG. Interestingly, the deletion of Tmem63a significantly reduced the macrophage infiltration in the DRG but not in the tibial nerve stump. Furthermore, the ablation of macrophages significantly reduced both the expression of Tmem63a and the mechanical allodynia in the TNT mouse model, indicating an interaction between nociceptors and macrophages, and that these two factors gang up together to regulate the formation of CPAP. This provides a new insight into the mechanisms underlying CPAP and potential drug targets its treatment.
Animals ; Mice ; Amputation, Surgical ; Chronic Pain/pathology* ; Disease Models, Animal ; Ganglia, Spinal/pathology* ; Hyperalgesia/etiology* ; Ion Channels/metabolism* ; Macrophages ; Neuroma/pathology*

Mechanical allodynia (MA), including punctate and dynamic forms, is a common and debilitating symptom suffered by millions of chronic pain patients. Some peripheral injuries result in the development of bilateral MA, while most injuries usually led to unilateral MA. To date, the control of such laterality remains poorly understood. Here, to study the role of microglia in the control of MA laterality, we used genetic strategies to deplete microglia and tested both dynamic and punctate forms of MA in mice. Surprisingly, the depletion of central microglia did not prevent the induction of bilateral dynamic and punctate MA. Moreover, in dorsal root ganglion-dorsal root-sagittal spinal cord slice preparations we recorded the low-threshold Aβ-fiber stimulation-evoked inputs and outputs of superficial dorsal horn neurons. Consistent with behavioral results, microglial depletion did not prevent the opening of bilateral gates for Aβ pathways in the superficial dorsal horn. This study challenges the role of microglia in the control of MA laterality in mice. Future studies are needed to further understand whether the role of microglia in the control of MA laterality is etiology-or species-specific.
Mice ; Animals ; Hyperalgesia/metabolism* ; Microglia/metabolism* ; Disease Models, Animal ; Spinal Cord/metabolism* ; Spinal Cord Dorsal Horn/metabolism* ; Ganglia, Spinal/metabolism*

Although sympathetic blockade is clinically used to treat pain, the underlying mechanisms remain unclear. We developed a localized microsympathectomy (mSYMPX), by cutting the grey rami entering the spinal nerves near the rodent lumbar dorsal root ganglia (DRG). In a chemotherapy-induced peripheral neuropathy model, mSYMPX attenuated pain behaviors via DRG macrophages and the anti-inflammatory actions of transforming growth factor-β (TGF-β) and its receptor TGF-βR1. Here, we examined the role of TGF-β in sympathetic-mediated radiculopathy produced by local inflammation of the DRG (LID). Mice showed mechanical hypersensitivity and transcriptional and protein upregulation of TGF-β1 and TGF-βR1 three days after LID. Microsympathectomy prevented mechanical hypersensitivity and further upregulated Tgfb1 and Tgfbr1. Intrathecal delivery of TGF-β1 rapidly relieved the LID-induced mechanical hypersensitivity, and TGF-βR1 antagonists rapidly unmasked the mechanical hypersensitivity after LID+mSYMPX. In situ hybridization showed that Tgfb1 was largely expressed in DRG macrophages, and Tgfbr1 in neurons. We suggest that TGF-β signaling is a general underlying mechanism of local sympathetic blockade.
Mice ; Animals ; Receptor, Transforming Growth Factor-beta Type I/metabolism* ; Transforming Growth Factor beta/pharmacology* ; Transforming Growth Factor beta1/metabolism* ; Hyperalgesia/metabolism* ; Radiculopathy/metabolism* ; Pain/metabolism* ; Analgesics/pharmacology* ; Ganglia, Spinal/metabolism*

Dorsal root ganglia (DRG) is an essential part of the peripheral nervous system and the hub of the peripheral sensory afferent. The dynamic changes of neuronal cells and their gene expression during the development of dorsal root ganglion have been studied through single-cell RNAseq analysis, while the dynamic changes of non-neuronal cells have not been systematically studied. Using single cell RNA sequencing technology, we conducted a research on the non-neuronal cells in the dorsal root ganglia of rats at different developmental stage. In this study, primary cell suspension was obtained from using the dorsal root ganglions (DRGs, L4-L5) of ten 7-day-old rats and three 3-month-old rats. The 10×Genomics platform was used for single cell dissociation and RNA sequencing. Twenty cell subsets were acquired through cluster dimension reduction analysis, and the marker genes of different types of cells in DRG were identified according to previous researches about DRG single cell transcriptome sequencing. In order to find out the non-neuronal cell subsets with significant differences at different development stage, the cells were classified into different cell types according to markers collected from previous researches. We performed pseudotime analysis of 4 types Schwann cells. It was found that subtype Ⅱ Schwann cells emerged firstly, and then were subtype Ⅲ Schwann cells and subtype Ⅳ Schwann cells, while subtype Ⅰ Schwann cells existed during the whole development procedure. Pseudotime analysis indicated the essential genes influencing cell fate of different subtypes of Schwann cell in DRG, such as Ntrk2 and Pmp2, which affected cell fate of Schwann cells during the development period. GO analysis of differential expressed genes showed that the up-regulated genes, such as Cst3 and Spp1, were closely related to biological process of tissue homeostasis and multi-multicellular organism process. The down regulated key genes, such as Col3a1 and Col4a1, had close relationship with the progress of extracellular structure organization and negative regulation of cell adhesion. This suggested that the expression of genes enhancing cell homestasis increased, while the expression of related genes regulating ECM-receptor interaction pathway decreased during the development. The discovery provided valuable information and brand-new perspectives for the study on the physical and developmental mechanism of Schwann cell as well as the non-neuronal cell changes in DRG at different developmental stage. The differential gene expression results provided crucial references for the mechanism of somatosensory maturation during development.
Rats ; Animals ; Ganglia, Spinal/metabolism* ; Rats, Sprague-Dawley ; Transcriptome ; Neurons/metabolism* ; Schwann Cells/physiology*

The Baimai Ointment with the effect of relaxing sinew and activating collaterals demonstrates a definite effect on Baimai disease with pain, spasm, stiffness and other symptoms, while the pharmacodynamic characteristics and mechanism of this agent remain unclear. In this study, a rat model of chronic compression of L4 dorsal root ganglion(CCD) was established by lumbar disc herniation, and the efficacy and mechanism of Baimai Ointment in the treatment of CCD were preliminarily explored by behavioral tests, side effect evaluation, network analysis, antagonist and molecular biology verification. The pharmacodynamic experiment indicated that Baimai Ointment significantly improved the pain thresholds(mechanical pain, thermal pain, and cold pain) and gait behavior of CCD model rats without causing tolerance or obvious toxic and side effects. Baimai Ointment inhibited the second-phase nociceptive response of mice in the formalin test, increased the hot plate threshold of normal mice, and down-regulated the expression of inflammatory cytokines in the spinal cord. Network analysis showed that Baimai Ointment had synergistic effect in the treatment of CCD and was related to descending inhibition/facilitation system and neuroinflammation. Furthermore, behavioral tests, Western blot, and immunofluorescence assay revealed that the pain-relieving effect of Baimai Ointment on CCD may be related to the regulation of the interaction between neuroactive ligand and receptors(neuroligands) such as CHRNA7, ADRA2A, and ADRB2, and the down-regulation of the expression of NOS2/pERK/PI3K, the core regulatory element of HIF-1 signaling pathway in spinal microglia. The findings preliminarily reveal the mechanism of relaxing sinew and activating collaterals of Baimai Ointment in the treatment of Baimai disease, providing a reference for the rational drug use and further research of this agent.
Rats ; Mice ; Animals ; Chronic Pain/metabolism* ; Rats, Sprague-Dawley ; Ganglia, Spinal/metabolism* ; Ligands ; Signal Transduction ; Hyperalgesia/metabolism* ; Drugs, Chinese Herbal

OBJECTIVES: Neuropathic pain (NP) is a chronic pain caused by somatosensory neuropathy or disease, and genistein (Gen) might be a potential drug for the treatment of NP. Therefore, this study aims to investigate the effect of Gen on lipopolysaccharide (LPS)-induced inflammatory injury of dorsal root ganglion neuron (DRGn) in rats and the possible molecular mechanism. METHODS: The DRGn of 1-day-old juvenile rats were taken for isolation and culture. The DRGn in logarithmic growth phase were divided into a control group, a LPS group, a tubastatin hydrochloride (TSA)+LPS group, a Gen1+LPS group, a Gen2+LPS group, a Gen2+LPS+TSA group, a Gen2+pcDNA-histone deacetylase 6 (HDAC6)+LPS group, and a Gen2+pcDNA3.1+LPS group. The LPS group was treated with 1 μg/mL LPS for 24 h; the TSA+LPS group, the Gen1+LPS group, the Gen2+LPS group were treated with 5 μmol/L TSA, 5 μmol/L Gen, 10 μmol/L Gen respectively for 0.5 h, and then added 1 μg/mL LPS for 24 h; the Gen2+TSA+LPS group was treated with 10 μmol/L Gen and 5 μmol/L TSA for 0.5 h and then added 1 μg/mL LPS for 24 h; the Gen2+pcDNA-HDAC6+LPS group and the Gen2+pcDNA3.1+LPS group received 100 nmol/L pcDNA-HDAC6 and pcDNA3.1 plasmids respectively, and 24 h after transfection, 10 μmol/L Gen was pretreated for 0.5 h, and then added 1 μg/mL LPS for 24 h. Real-time RT-PCR was used to detect the HDAC6 mRNA expression in DRGn; CCK-8 method was used to detect cell viability of DRGn; flow cytometry was used to detect cell apoptosis of DRGn; ELISA was used to detect the levels of IL-1β, IL-6, and TNF-α in DRGn culture supernatant; Western blotting was used to detect the protein expression of HDAC6, Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and NF-κB p65 in DRGn. RESULTS: Compared with the control group, the expression levels of HDAC6 mRNA and protein, the expression levels of TLR4 and MyD88 protein in DRGn of LPS group rats were significantly up-regulated, the ratio of p-NF-κB p65/NF-κB p65 was significantly increased, and the activity of DRGn was significantly decreased, the apoptosis rate was significantly increased, and the levels of IL-1β, IL-6 and TNF-α in the DRGn culture supernatant were significantly increased (all P<0.05). Compared with the LPS group, the expression levels of HDAC6 mRNA and protein, TLR4 and MyD88 protein expression levels in DRGn of the TSA+LPS group, the Gen1+LPS group, the Gen2+LPS group and the Gen2+TSA+LPS group were significantly down-regulated, the ratio of p-NF-κB p65/NF-κB p65 was significantly decreased, the activity of DRGn was significantly increased, the apoptosis rate was significantly decreased, and the levels of IL-1β, IL-6 and TNF-α in the DRGn culture supernatant were significantly decreased (all P<0.05), and the above changes were most obvious in the Gen2+TSA+LPS group. Compared with the Gen2+LPS group, the expression levels of HDAC6 mRNA and protein, TLR4 and MyD88 protein expression levels in DRGn of the Gen2+pcDNA-HDAC6+LPS group were significantly up-regulated, the ratio of p-NF-κB p65/NF-κB p65 was significantly increased, the activity of DRGn was significantly decreased, and the apoptosis rate was significantly increased, and the levels of IL-1β, IL-6 and TNF-α in the DRGn culture supernatant were significantly increased (all P<0.05). CONCLUSIONS Gen can alleviate LPS-induced DRGn inflammatory injury in rats, which might be related to down-regulating the expression of HDAC6 and further inhibiting the activation of TLR4/MyD88/NF-κB signaling pathway.
Animals ; Ganglia, Spinal ; Genistein/pharmacology* ; Histone Deacetylase 6/metabolism* ; Interleukin-6/metabolism* ; Lipopolysaccharides ; Myeloid Differentiation Factor 88 ; NF-kappa B/metabolism* ; Neurons/metabolism* ; RNA, Messenger ; Rats ; Toll-Like Receptor 4/metabolism* ; Tumor Necrosis Factor-alpha/metabolism*