Effects of miR-141-3p on dorsal root ganglion inflammation and lower limb pain in rats with lumbar disc herniation / 中国组织工程研究

BACKGROUND:Studies have shown that insulin-like growth factor 1/platelet-derived growth factor has an inhibitory effect on fibroblast apoptosis.miR-141-3p in bone marrow stromal cells increases with age and has a relationship with the activation of inflammatory signaling pathways,suggesting that it may be a therapeutic target for lumbar disc herniation. OBJECTIVE:To explore the effects of miR-141-3p on dorsal root ganglion inflammation and lower limb pain in rats with lumbar disc herniation by regulating insulin-like growth factor 1/platelet-derived growth factor. METHODS:Fifty male Sprague-Dawley rats,SPF level,were randomly divided into normal group,model group,miR-NC group,miR-141-3p inhibitor group and miR-141-3p mimics group,with 10 rats in each group.Except for the normal group,animal models of lumbar disc herniation were established in rats by autologous nucleus pulposus transplantation.After successful modeling,rats in the miR-NC,miR-141-3p inhibitor and miR-141-3p mimics groups were injected intrathecally with 10 μL of 20 μmol/L miR-NC,miR-141-3p inhibitor,miR-141-3p mimics,once a day for 28 days,respectively,while those in the normal and model groups were injected with the same volume of saline at the same location at the same time.Paw withdrawal thermal latency threshold was used to evaluate lower limb pain in rats.The mRNA expression of miR-141-3p in dorsal root ganglion tissue was detected by real-time fluorescence quantitative PCR,the levels of inflammatory factors in dorsal root ganglion tissue were detected by ELISA,and the expression of insulin-like growth factor 1/platelet-derived growth factor in dorsal root ganglion tissue was detected by western blot.The correlation between miR-141-3p and insulin-like growth factor 1/platelet-derived growth factor was analyzed. RESULTS AND CONCLUSION:There were no significant differences in all indexes between the miR-NC group and the model group.Paw withdrawal thermal latency threshold was significantly lower in the model group than in the normal group(P＜0.05),significantly lower in the miR-141-3p inhibitor group than the miR-NC group(P＜0.05),and significantly higher in the miR-141-3p mimics group than in the miR-141-3p inhibitor group(P＜0.05).The mRNA expression of miR-141-3p in dorsal root ganglion tissue was significantly lower in the model group than in the normal group(P＜0.05),significantly lower in the miR-141-3p inhibitor group than in the miR-NC group(P＜0.05),and significantly higher in the miR-141-3p mimics group than in the miR-141-3p inhibitor group(P＜0.05).The levels of tumor necrosis factor α,interleukin 1β,and interleukin 1 in dorsal root ganglion tissue were significantly higher in the model group than in the normal group(P＜0.05),significantly higher in the miR-141-3p inhibitor group than in the miR-NC group(P＜0.05),and significantly lower in the miR-141-3p mimics group than in the miR-141-3p inhibitor group(P＜0.05).The protein expressions of insulin-like growth factor 1 and platelet-derived growth factor in dorsal root ganglion tissue were significantly lower in the model group than in the normal group(P＜0.05),significantly lower in the miR-141-3p inhibitor group than in the miR-NC group(P＜0.05),and significantly higher in the miR-141-3p mimics group than in the miR-141-3p inhibitor group(P＜0.05).The expressions of insulin-like growth factor 1 and platelet-derived growth factor showed a positive correlation with miR-141-3p(r=0.904,P＜0.001;r=0.879,P＜0.001).To conclude,miR-141-3p can significantly improve lower limb pain and inhibit inflammation in dorsal root ganglia in rats with lumbar disc herniation,and its mechanism may be related to the promotion of insulin-like growth factor 1/platelet-derived growth factor expression.

Effects of ZXDC Mediates CCL2 on Chronic Neuropathic Pain in Spinal Dorsal Root Ganglion / 医学研究杂志

Objective To explore the effect and mechanism of C-C motif chemokine ligand 2(CCL2)/C-C chemokine receptor type 2(CCR2)signaling pathway mediated by ZXDC in spinal dorsal root ganglion(DRG)on neuropathic pain after chronic compressive injury.Methods A chronic compressive injury(CCI)mouse model was established.The expression of ZXDC and CCL2 in DRG was detected by immunofluorescence,Western blot,and real-time fluorescent quantitative PCR(RT-qPCR).The animals were divided in-to sham group,CCI+AAV-NC group,and CCI+AAV-ZXDC siRNA group.Western blot and immunofluorescence were employed to measure the expression of ZXDC,CCL2,and CCR2 in DRG after CCI,and the expression of pro-inflammatory factor TNF-α and IL-1β mRNA was evaluated by RT-qPCR.At last,the paw withdrawal threshold was used to evaluate the changes in neuropathic pain be-havior.Results ZXDC was localized in large,medium,and small DRG neurons.The expression of ZXDC and CCL2 protein and mRNA were significantly increased 1-3 days after CCI,and decreased 7days after CCI in DRG.The expression of ZXDC and CCL2mRNA was positively correlated(P＜0.05).3 days after CCI,compared with sham group,ZXDC,CCL2,CCR2 protein expression,TNF-α and IL-1 β mRNA in CCI+AAV-NC group and CCI+AAV-ZXDC siRNA group were significantly increased,and ZXDC,CCL2,CCR2 protein expression,TNF-α and IL-1 β mRNA in CCI+AAV-ZXDC siRNA group were significantly decreased than those in CCI+AAV-NC group(P＜0.05).Compared with sham group,the paw withdrawal threshold of CCI+AAV-ZXDC siRNA group and CCI+AAV-NC group were significantly decreased at various time points after CCI,and the withdrawal threshold in CCI+AAV-ZXDC siRNA group was significantly increased than that in CCI+AAV-NC group at 7days after CCI(P＜0.05).Conclusion Spinal dorsal root gan-glion ZXDC siRNA can inhibit neuropathic pain after CCI injury by downregulating CCL2/CCR2signaling axis.

Progress in mechanism of complement system involved in pathological pain / 中国病理生理杂志

The complement system comprises intrinsic complement components,complement regulatory pro-teins,and complement receptors.Complement activation plays a role in promoting the sensitization of peripheral pain re-ceptors,enhancing immune cell activity,and participating in the regulation of axon regeneration after nerve injury.The in-teraction of the complement system contributes to the development and maintenance of pathological pain,affecting the dor-sal root ganglion neurons,spinal dorsal horn,and brain.Consequently,targeting the complement system holds promise as a therapeutic approach for neuropathic pain treatment.This paper reviews the progress in understanding the functions of the complement system and its implications in pathological pain,offering valuable insights for the future development of targeted drug therapies.

Dorsal root ganglion-derived exosomes deteriorate neuropathic pain by activating microglia via the microRNA-16-5p/HECTD1/ HSP90 axis

Background The activated microglia have been reported as pillar factors in neuropathic pain (NP) pathology, but the molecules driving pain-inducible microglial activation require further exploration. In this study, we investigated the effect of dorsal root ganglion (DRG)-derived exosomes (Exo) on microglial activation and the related mechanism. Methods A mouse model of NP was generated by spinal nerve ligation (SNL), and DRG-derived Exo were extracted. The effects of DRG-Exo on NP and microglial activation in SNL mice were evaluated using behavioral tests, HE staining, immunofluorescence, and western blot. Next, the differentially enriched microRNAs (miRNAs) in DRG-Exo-treated microglia were analyzed using microarrays. RT-qPCR, RNA pull-down, dual-luciferase reporter assay, and immunofluorescence were conducted to verify the binding relation between miR-16-5p and HECTD1. Finally, the effects of ubiquitination modification of HSP90 by HECTD1 on NP progression and microglial activation were investigated by Co-IP, western blot, immunofluorescence assays, and rescue experiments. Results DRG-Exo aggravated NP resulting from SNL in mice, promoted the activation of microglia in DRG, and increased neuroinflammation. miR-16-5p knockdown in DRG-Exo alleviated the stimulating effects of DRG-Exo on NP and microglial activation. DRG-Exo regulated the ubiquitination of HSP90 through the interaction between miR-16-5p and HECTD1. Ubiquitination alteration of HSP90 was involved in microglial activation during NP. Conclusions miR-16-5p shuttled by DRG-Exo regulated the ubiquitination of HSP90 by interacting with HECTD1, thereby contributing to the microglial activation in NP.

Potentiation of PIEZO2 mechanically-activated currents in sensory neurons mediates vincristine-induced mechanical hypersensitivity

Vincristine, a widely used chemotherapeutic agent for treating different cancer, often induces severe peripheral neuropathic pain. A common symptom of vincristine-induced peripheral neuropathic pain is mechanical allodynia and hyperalgesia. However, mechanisms underlying vincristine-induced mechanical allodynia and hyperalgesia are not well understood. In the present study, we show with behavioral assessment in rats that vincristine induces mechanical allodynia and hyperalgesia in a PIEZO2 channel-dependent manner since gene knockdown or pharmacological inhibition of PIEZO2 channels alleviates vincristine-induced mechanical hypersensitivity. Electrophysiological results show that vincristine potentiates PIEZO2 rapidly adapting (RA) mechanically-activated (MA) currents in rat dorsal root ganglion (DRG) neurons. We have found that vincristine-induced potentiation of PIEZO2 MA currents is due to the enhancement of static plasma membrane tension (SPMT) of these cells following vincristine treatment. Reducing SPMT of DRG neurons by cytochalasin D (CD), a disruptor of the actin filament, abolishes vincristine-induced potentiation of PIEZO2 MA currents, and suppresses vincristine-induced mechanical hypersensitivity in rats. Collectively, enhancing SPMT and subsequently potentiating PIEZO2 MA currents in primary afferent neurons may be an underlying mechanism responsible for vincristine-induced mechanical allodynia and hyperalgesia in rats. Targeting to inhibit PIEZO2 channels may be an effective analgesic method to attenuate vincristine-induced mechanical hypersensitivity.

Deciphering the dynamic characteristics of non-neuronal cells in dorsal root ganglion of rat at different developmental stage based on single cell transcriptome data / 生物工程学报

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.

Analgesic Effect of Intrathecal 2R， 6R-HNK on Neuropathic Pain in Female Mice / 中山大学学报(医学科学版)

ObjectiveTo investigate the analgesic action and mechanism of intrathecal 2R， 6R-hydroxynorketamine （2R， 6R-HNK） on spared nerve injury （SNI）-induced chronic neuropathic pain （CNP） in female mice. MethodsSNI was used to establish acute and chronic CNP models in female mice. The mice were randomly divided into different groups with administration of vehicle， 2R， 6R-HNK or S-ketamine （10 mg/kg intraperitoneal injection/i.p. or 7， 21 μmol/L intrathecal injection/i.t.） at 3 weeks after or 30 min/1 d before operation （n = 3 - 7 mice/group）. The curative or preventive effect of 2R， 6R-HNK was evaluated by mechanical paw withdrawal threshold （PWT） and the analgesic efficiency. Finally， immunofluorescence and RT-PCR of dorsal root ganglion （DRG） and spinal dorsal horn （SDH） were used to explore the possible mechanisms. ResultsCompared with vehicle， intrathecal injection of 2R， 6R-HNK largely reversed SNI-induced bilateral mechanical allodynia in a delayed-and-dose-dependent way. Among them， 21 μmol/L 2R， 6R-HNK reached its maximum analgesic efficiency （75.32±7.69） % at 2 d. Pre-intrathecal delivery of 2R， 6R-HNK also delayed the development of bilateral mechanical hypersensitivity 2 - 3 d induced by SNI. Mechanically， 2R， 6R-HNK reversed not only the abnormal excitability of neurons in bilateral DRG and superficial SDH， but also the upregulation of calcitonin gene-related peptide （CGRP） and brain-derived nerve growth factor （BDNF） in DRG. ConclusionIntrathecal administration of 2R， 6R-HNK exerts an analgesic effect against CNP， probably via suppressing abnormal neuronal excitability in ascending pain pathway as well as down-regulating CGRP and BDNF expression in DRG neurons.

Remifentanil Down-regulates GIRK2 Expression in Rat Dorsal Root Ganglion and Spinal Dorsal Horn / 中山大学学报(医学科学版)

ObjectiveTo observe the changes in the expression and distribution of G protein-gated inwardly rectifying potassium channel subunit 2 （GIRK2） in the dorsal root ganglion （DRG） and spinal cord dorsal horn of rats with remifentanil-induced hyperalgesia. MethodsHyperalgesia was induced by intravenous infusion of remifentanil 4 μg/kg/min for 2 h in adult male SD rats. At 6th hour and on days 1， 3 and 5 following remifentanil treatment， we used immunofluorescence to examine the changes in the GIRK2 distribution and expression. Immunoblotting was used to detect GIRK2 expression of the total protein and membrane protein in DRG and spinal dorsal horn of rats. Behavioral testing was applied to evaluate the effect of intrathecal injection of GIRK2-specific agonist ML297 on thermal nociceptive threshold on day 1 after remifentanil infusion. Resultsmmunofluorescence results showed that GIRK2 was mainly co-localized with IB4-positive small neurons in DRG and nerve fibers in spinal dorsal horn. GIRK2 expression was significantly downregulated following remifentanil treatment. Immunoblotting results revealed that on day 1 following intravenous infusion of remifentanil， compared with those in the control group， GIRK2 expression levels of the total protein and membrane protein in DRG （0.47 ± 0.10 vs. 1.01 ± 0.17， P < 0.001； 0.47 ± 0.11 vs. 1.06 ± 0.12， P < 0.001） and spinal dorsal horn （0.52 ± 0.09 vs. 1.10 ± 0.08， P < 0.001； 0.54 ± 0.10 vs. 1.01 ± 0.13， P < 0.001） were all significantly decreased. The behavioral results showed that intrathecal ML297 effect on thermal withdrawal latency was significantly reduced following remifentanil treatment （P < 0.001）. ConclusionsRemifentanil might induce hyperalgesia via down-regulating GIRK2 expression in rat DRG and spinal cord dorsal horn.

Analgesic Effect and Mechanism of Osteoking on Dorsal Root Ganglion Compression Model Rats / 中国实验方剂学杂志

ObjectiveTo investigate the analgesic effect and mechanism of Osteoking （OK） on nerve compression in lumbar disc herniation. MethodThe rat model of chronic compression of dorsal root ganglion （CCD） was established to simulate clinical lumbar disc herniation. The CCD rats were randomly divided into model group， low， medium， and high dose OK groups （1.31， 2.63， 5.25 mL·kg-1·d-1）， and pregabalin group （5 mg·kg-1）， with eight rats in each group. Another eight SD rats were taken as the blank group， and the same volume of normal saline was given by gavage. Behavioral tests， side effect evaluation， network analysis， Western blot， immunofluorescence， and antagonist application were used to explore the effect. ResultCompared with the blank group， the mechanical hyperalgesia threshold， thermal hyperalgesia threshold， and the expression of inflammatory factors in the spinal dorsal horn of the model group are significantly increased （P<0.01）， and the related indicators of the affected foot footprints are significantly down-regulated （P<0.01）. The expression of signal transducer and activator of transcription 3 （STAT3）， vascular endothelial growth factor A （VEGFA）， and phosphorylated extracellular regulated protein kinase （p-ERK） in microglia in the spinal dorsal horn is significantly increased in the model group （P<0.01）. Compared with the model group， low， medium， and high dose OK groups can increase the mechanical hyperalgesia and thermal hyperalgesia thresholds of CCD rats （P<0.05， P<0.01） in a dose-dependent manner， improve the gait of CCD rats （P<0.05， P<0.01）， and reduce the expression of inflammatory factors in the spinal dorsal horn （P<0.05， P<0.01）. The expression of STAT3， VEGFA， and p-ERK in the spinal dorsal horn microglia of CCD rats is significantly decreased （P<0.05， P<0.01）， and the acetic acid-induced nociceptive response in rats is effectively reduced （P<0.05， P<0.01）. In addition， there is no tolerance. The results of the body mass test， organ index， forced swimming， and rotation show that OK has no obvious toxic or side effects. Further antagonist experiments show that MRS1523 and RS127445 can reverse the transient analgesic effect of OK compared with the high dose OK group （P<0.01）. ConclusionOK has a good analgesic effect on the CCD model without obvious toxic side effects， and its mechanism may be related to the activation of ADORA3 and HTR2B and the inhibition of STAT3， VEGFA， p-ERK， and other elements in microglia.

Effect of endomorphin 2 on expression of μ⁃opioid receptors in the dorsal root ganglion in rats with neuropathic pain / 安徽医科大学学报

Objective @#To explore the expression of the μ⁃opioid receptor ( MOR) and the effects of intracellular vesicle transport on the MOR expression during endomorphin 2 ( EM2) analgesia. @*Methods @# Adult male SD rats were randomly divided into 3 groups : control (naive) group , neuropathic pain group and drug group. Spared nerve injury (SNI) induced neuropathic pain rats were employed as the pain model. The drug group rats were the SNI pain ones intrathecally injected with EM2. The methods of immunofluorescence single staining and Western blot were used to detect the expression of MOR total protein , phosphorylated protein and Rab7 protein. Immunofluorescence double staining was used to detect the expression of MOR/Rab7 and MOR/LAMP1 co⁃labeled immunoreactivity.@*Results @#Compared with the control group , the expression of total MOR protein and phosphorylated protein in the dorsal root ganglion (DRG) of the SNI pain rats decreased (P < 0. 05) , and the expression of Rab7 significantly increased (P < 0. 05) . The expression of MOR/Rab7 co⁃labeled immunoreactivity in Rab7 and MOR immunoreactive ( Ⅳir) products and MOR/LAMP1 co⁃labeled immunoreactivity in MOR and LAMP1 ⁃ir products both increased (P < 0. 05) . Multiple intrathecal injection of EM2 significantly increased paw withdrawal threshold in the SNI neuropathic pain rats (P < 0. 01) , the expression of MOR protein and phosphorylated protein in DRG was increased (P < 0. 05) , while the expression of Rab7 decreased (P < 0. 05) . Compared with the control group , the expression of MOR/Rab7 positive products in Rab7 and MOR positive ones decreased , and the expression of MOR/LAMP1 positive products in LAMP1 and MOR positive markers decreased ( P < 0. 05 ) . @*Conclusion @#In the process of analgesia , EM2 inhibits the expression of Rab7 in the DRG of SNI neuropathic pain rats , reduces the transport of MOR to lysosomes , and promotes the re⁃sensitization of MOR.

An experimental study of tangzhouling on morphological changes of nissl bodies in the dorsal root ganglion of DM rats / Un estudio experimental de tangzhouling sobre los cambios morfológicos de los cuerpos de nissl en el ganglio de la raíz dorsal de ratas DM

SUMMARY: This study aims to investigate the effect of Tangzhouling on the morphological changes of Nissl bodies in the dorsal root ganglion of DM Rats. In this study, 69 rats were randomly divided into a control group (n = 10) and a model group (n = 59). The rats in the model group were randomly divided into a diabetic group (n = 11), a vitamin C group (n = 12), a low dose Tangzhouling group (n = 12), a medium dose Tangzhouling group (n = 12) and a high dose Tangzhouling group (n = 12). The dose of Tangzhouling in the low dose group was 5 times that of the adult dose, being 0.44g/kg/d. The dose of Tangzhouling in the medium dose group was 10 times that of the adult dose, being 0.88g/kg/d. The dose of Tangzhouling in the high dose group was 20 times that of the adult dose, being 1.75g/kg/d. All doses above are crude drug dosages. Rats in the vitamin C group were given 10 times the dose of an adult, being, 0.05 g/ kg/d. The diabetic group and the control group were given the same amount of distilled water. Drug delivery time is 16 weeks. The dorsal root ganglion was placed in a freezing tube at the end of the experiment. The morphological changes of Nissl bodies in the dorsal root ganglion were detected by HE and Nissl staining. The study results showed that vitamin C had no significant effect on the quantity, size and nucleolus. Tangzhouling can improvee the morphology, quantity and nucleolus of Nissl bodies to a certain extent, and the high dose is better than the lower dose. Tangzhouling capsules can improve the nerve function of DM rats through Nissl bodies.

RESUMEN: Este estudio tuvo como objetivo investigar el efecto de Tangzhouling en los cambios morfológicos de los cuerpos de Nissl en el ganglio de la raíz dorsal de las ratas DM. En este estudio, 69 ratas se dividieron aleatoriamente en un grupo control (n = 10) y un grupo modelo (n = 59). Las ratas del grupo modelo se dividieron aleatoriamente en un grupo diabéticos (n = 11), un grupo vitamina C (n = 12), un grupo de dosis baja de Tangzhouling (n = 12), un grupo de dosis media de Tangzhouling (n = 12) y un grupo de dosis alta de Tangzhouling (n = 12). La dosis de Tangzhouling en el grupo de dosis baja fue 5 veces mayor que la dosis del adulto, siendo 0,44 g/kg/d. La dosis de Tangzhouling en el grupo de dosis media fue 10 veces mayor que la dosis del adulto, siendo 0,88 g/kg/d. La dosis de Tangzhouling en el grupo de dosis alta fue 20 veces mayor que la dosis del adulto, siendo 1,75 g/kg/d. Todas las dosis anteriores son dosis de fármaco crudo. Se les administró 10 veces la dosis de un adulto a las ratas del grupo vitamina C, siendo 0,05 g/kg/d. El grupo de diabéticos y el grupo de control recibieron la misma cantidad de agua destilada. El tiempo de entrega del fármaco fue de 16 semanas. El ganglio de la raíz dorsal se colocó en un tubo de congelación al final del experimento. Los cambios morfológicos de los cuerpos de Nissl en el ganglio de la raíz dorsal se detectaron mediante tinción de HE y Nissl. Los resultados del estudio mostraron que la vitamina C no tuvo un efecto significativo sobre la cantidad, el tamaño y el nucléolo. Tangzhouling puede mejorar la morfología, la cantidad y el nucléolo de los cuerpos de Nissl hasta cierto punto, y es mejor la dosis alta que la dosis baja. Las cápsulas de Tangzhouling pueden mejorar la función nerviosa de las ratas DM a través de los cuerpos de Nissl.

Analgesic effect of α-cobratoxin on mice and its effect on protein kinase A activity of spinal dorsal root ganglion in mice / 中华行为医学与脑科学杂志

Objective:To study the analgesic effect of α-cobratoxin (α-CbTX) on mice and its effect on protein kinase A (PKA) activity of spinal dorsal root ganglion (DRG) in mice.Methods:Healthy male ICR mice( n=102) were randomly divided into low-, medium-, and high-dose α-CbTX groups (1 mg/kg, 3 mg/kg, 9 mg/kg respectively, gavage, n=21), solvent control group (equivalent volume of 0.9% normal saline, gavage, n=21), morphine positive control group (3 mg/kg, intraperitoneal injection, n=6)or aspirin positive control group(300 mg/kg, gavage, n=12). The analgesic effect of α-CbTX was evaluated by hot plate test, acetic acid twisting test and formalin foot licking test. Formalin plantar injection was used to induce pain and then the L4-L6 DRG was taken 30 minutes later. The expression of PKA C-α in L4-L6 DRG of mice were detected by Western blot.SPSS 16.0 software was used for statistical analysis. Repeated measurement ANOVA was used to evaluate the hot plate experimental data, and one-way ANOVA was used for other experimental data. LSD- t test was used for further pairwise comparison. Results:In the hot plate test, the interaction between group and time of mice paw licking latency was significant ( F=8.902, P<0.05). At 0.5 h after administration, the paw licking latencies of α-CbTX medium-dose group ((11.83±1.47)s)and α-CbTX high-dose group (( 14.33±12.1)s) were both longer than that of solvent control group((8.17±0.75) s) ( t=4.461, 7.053, both P<0.05). The efficacy of α-CbTX medium dose group lasted until 1.5 h after administration (all P<0.05), and that of α-CbTX high dose group lasted until 2 h after administration(all P<0.05). In the acetic acid writhing test, the writhing times in the low-, medium- and high-dose α-CbTX group((34.50±3.62) times, (26.17±2.40) times, (13.83±3.76) times)) were significantly lower than that in solvent control group ((42.50±4.59) times) ( t=3.938, 8.040, 14.112, all P<0.05). In the period of the formalin test phase Ⅱ, the total licking time of α-CbTX low-, medium- and high-dose groups ((71.17±6.46) s), (54.67±6.41) s, (40.50±3.89)s) were significantly shorter than that of the solvent control group ((98.67±11.50) s)( t=6.950, 11.120, 14.700, all P<0.05). In the Western blot experiment, compared with solvent control group (0.22±0.01), the levels of PKA C-α in the DRG of mice in low-, medium- and high-dose α-CbTX groups ((0.31±0.02), (0.41±0.03), (0.44±0.02)) were up-regulated ( t=3.140, 6.471, 7.492, all P<0.05). Conclusion:α-CbTX has obvious analgesic effect, and its analgesic mechanism may be related to the activation of PKA.

Protective Mechanism of Electroacupuncture on Peripheral Neurotoxicity Induced by Oxaliplatin in Rats / 中国结合医学杂志

OBJECTIVE@#To study the effect of electroacupuncture (EA) on oxaliplatin-induced peripheral neuropathy (OIPN) in rats.@*METHODS@#Male Sprague-Dawley rats were equally divided into 3 groups using a random number table: the control group, the OIPN group, and the EA (OIPN + EA) group, with 10 rats in each. The time courses of mechanical, cold sensitivity, and microcirculation blood flow intensity were determined. The morphology of the dorsal root ganglion (DRG) was observed by electron microscopic examination. The protein levels of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the transient receptor potential (TRP) protein family in DRGs were assayed by Western blot.@*RESULTS@#EA treatment significantly reduced mechanical allodynia and cold allodynia in OIPN rats (P<0.01). Notably, oxaliplatin treatment resulted in impaired microcirculatory blood flow and pathomorphological defects in DRGs (P<0.01). EA treatment increased the microcirculation blood flow and attenuated the pathological changes induced by oxaliplatin (P<0.01). In addition, the expression levels of Nrf2 and HO-1 were down-regulated, and the TRP protein family was over-expressed in the DRGs of OIPN rats (P<0.01). EA increased the expression levels of Nrf2 and HO-1 and decreased the level of TRP protein family in DRG (P<0.05 or P<0.01).@*CONCLUSION@#EA may be a potential alternative therapy for OIPN, and its mechanism may be mainly mediated by restoring the Nrf2/HO-1 signaling pathway.

Genistein attenuates LPS-induced inflammatory injury of rat dorsal root ganglion neuron via down-regulating HDAC6 / 中南大学学报(医学版)

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.

Recent advance in mechanism of advanced glycation end-product receptors in pathological pain / 中华神经医学杂志

The advanced glycation end-products (RAGE) receptors are a kind of new pattern-recognition receptors, which express in both immune cells and nerve cells. New studies have shown that aberrant activation of RAGE involves in pathological pain, and inhibiting the activation of RAGE can prevent or alleviate pathological pain in animals. In this paper, we review the recent literatures in the involvement of RAGE in pathological pain, and discuss the possibility and challenges of RAGE as a therapeutic target for pathological pain.

Research of high glucose on the injury of dorsal root ganglion cells / 国际外科学杂志

Diabetic bladder dysfunction is one of the most common complications of urinary tract in diabetes. It is believed that the disorders of glucose metabolism, local tissue ischemia, superoxide-induced free radical production and axonal transport disorder are all involved in the development of diabetic bladder nerve dysfunction. Oxidative stress is believed to be the core mechanism of the above mentioned etiology. It may affect the transcription and translation process in the nucleus by interfering with the balance of intracellular oxidation and antioxidant, metabolism of neurotrophic factors and cellular signal transduction pathways, resulting in dysfunction of several important cellular pathways and decreased membrane stability. And eventually lead to nerve cell apoptosis. Therefore, controlling blood glucose, improving the microenvironment around dorsal root neurons, and protecting the stability of mitochondrial membrane may be potential methods for the treatment of diabetic bladder nerve dysfunction.

Growth Differentiation Factor-15 Produces Analgesia by Inhibiting Tetrodotoxin-Resistant Nav1.8 Sodium Channel Activity in Rat Primary Sensory Neurons / 神经科学通报·英文版

Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. It is widely distributed in the central and peripheral nervous systems. Whether and how GDF-15 modulates nociceptive signaling remains unclear. Behaviorally, we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats. Electrophysiologically, we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia (DRG) neurons. Furthermore, GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents, and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction. GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels, suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel. Immunohistochemistry results showed that activin receptor-like kinase-2 (ALK2) was widely expressed in DRG medium- and small-diameter neurons, and some of them were Nav1.8-positive. Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors. Inhibition of PKA and ERK, but not PKC, blocked the inhibitory effect of GDF-15 on Nav1.8 currents. These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK, which mediate the peripheral analgesia of GDF-15.

Expression and distribution of annexin A2 in dorsal root ganglion after chronic compression of dorsal root ganglion in rats / 中华神经医学杂志

Objective:To explore the annexin A2 (ANXA2) expression and distribution in dorsal root ganglion (DRG) after chronic compression of DRG (CCD) in rat models.Methods:One hundred and two adult male Wistar rats were randomly divided into control group ( n=24), CCD model group A (7 d after modeling, n=30), CCD model group B (14 d after modeling, n=24), and CCD model group D (28 d after modeling, n=24). Rats in the later 3 groups were established CCD models with the help of "U" rod screw. Mechanical withdrawal threshold (MWT) and thermal radiation paw withdrawal latency (TWL) were measured by mechanical pain stimulator and thermal pain stimulator. The ANXA2 protein expression in the DRG was detected by Western blotting and immunofluorescent staining. The distributions of ANXA2 and class III β-tubulin (TUBB3) positive cells in DRG were detected by immunofluorescence double staining. Results:As compared with those in the control group, MWT and TWL in the CCD model group A and CCD model group B were significantly decreased ( P<0.05). Western blotting showed that ANXA2 protein expression in the DRG of CCD model group A was statistically increased as compared with that in the control group ( P<0.05). Immunofluorescent staining showed that the immunoreactivity of ANXA2 in DRG of CCD model group A was enhanced as compared with that in control group. Immunofluorescence double staining showed that ANXA2 was mainly expressed in the cell membrane of neurons in the DRG of CCD model group A. Conclusion:The mechanical and thermal pain thresholds are decreased, while the ANXA2 protein expression at the pressure side of DRG is up-regulated and the immunoreactivity is increased in CCD models; ANXA2 may be involved in the occurrence and development of pathological neuralgia after CCD.

Growth Differentiation Factor-15 Produces Analgesia by Inhibiting Tetrodotoxin-Resistant Nav1.8 Sodium Channel Activity in Rat Primary Sensory Neurons / 神经科学通报·英文版

Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. It is widely distributed in the central and peripheral nervous systems. Whether and how GDF-15 modulates nociceptive signaling remains unclear. Behaviorally, we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats. Electrophysiologically, we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia (DRG) neurons. Furthermore, GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents, and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction. GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels, suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel. Immunohistochemistry results showed that activin receptor-like kinase-2 (ALK2) was widely expressed in DRG medium- and small-diameter neurons, and some of them were Nav1.8-positive. Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors. Inhibition of PKA and ERK, but not PKC, blocked the inhibitory effect of GDF-15 on Nav1.8 currents. These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK, which mediate the peripheral analgesia of GDF-15.

Improving neuronal transfection by electroporation of dorsal root ganglion / 中国组织工程研究

BACKGROUND: Electroporation of dorsal root ganglion is a high-efficiency gene transfection method to study nerve regeneration. In the past, the voltage condition of dorsal root ganglion electroporation resulted in a reduction in the number of labeled neurons and axons, with a high statistical error. OBJECTIVE: To improve the marker rate of neurons and their axons, and to provide theoretical basis for the study of peripheral nerve regeneration. METHODS: The enhanced green fluorescent protein was as an outcome measure to optimize dorsal root ganglion electroporation in axonal regeneration. ICR mice were randomly divided into two groups, respectively, and underwent dorsal root ganglion electroperforation surgery to detect the labeling rates of neurons and their axons under the intervention of 35 and 60 V voltages. RESULTS AND CONCLUSION: Voltages at 35 and 60 V did not cause significant neuronal death. Compared with 35 V voltage, 60 V voltage significantly increased the labeling rate of neurons and their axons as well as the number of axons passing through the injured site (P < 0.05). The 60 V voltage did not damage the behavioral function of the experimental animals. These results suggest that 60 V voltage can increase the labeling rate of neurons and their axons, providing a basis for the study of axonal regeneration in peripheral nerves.