The dorsal root ganglion as a target for neurorestoration in neuropathic pain

Neuropathic pain is a severe and chronic condition widely found in the general population.The reason for this is the extensive variety of damage or diseases that can spark this unpleasant constant feeling in patients.During the processing of pain,the dorsal root ganglia constitute an important region where dorsal root ganglion neurons play a crucial role in the transmission and propagation of sensory electrical stimulation.Furthermore,the dorsal root ganglia have recently exhibited a regenerative capacity that should not be neglected in the understanding of the development and resolution of neuropathic pain and in the elucidation of innovative therapies.Here,we will review the complex interplay between cells(satellite glial cells and inflammatory cells)and factors(cytokines,neurotrophic factors and genetic factors)that takes place within the dorsal root ganglia and accounts for the generation of the aberrant excitation of primary sensory neurons occurring in neuropathic pain.More importantly,we will summarize an updated view of the current pharmacologic and nonpharmacologic therapies targeting the dorsal root ganglia for the treatment of neuropathic pain.

Gene expression changes in dorsal root ganglia following peripheral nerve injury: roles in inflammation,cell death and nociception

Subsequent to a peripheral nerve injury, there are changes in gene expression within the dorsal root ganglia in response to the damage. This review selects factors which are well-known to be vital for inflammation, cell death and nociception, and highlights how alterations in their gene expression within the dorsal root ganglia can affect functional recovery. The majority of studies used polymerase chain reaction within animal models to analyse the dynamic changes following peripheral nerve injuries. This review aims to highlight the factors at the gene expression level that impede functional recovery and are hence are potential targets for therapeutic approaches. Where possible the experimental model, specific time-points and cellular location of expression levels are reported.

Differential expression of microRNAs in dorsal root ganglia after sciatic nerve injury

This study investigated the possible involvement of microRNAs in the regulation of genes that participate in peripheral neural regeneration. A microRNA microarray analysis was conducted and 23 microRNAs were identiifed whose expression was signiifcantly changed in rat dorsal root ganglia after sciatic nerve transection. The expression of one of the downregulated microRNAs, microRNA-214, was validated using quantitative reverse transcriptase-PCR. MicroRNA-214 was predicted to target the 3′-untranslated region of Slit-Robo GTPase-activating protein 3. In situ hybridization veriifed that microRNA-214 was located in the cytoplasm of dorsal root ganglia primary neurons and was downregulated following sciatic nerve transection. Moreover, a com-bination of in situ hybridization and immunohistochemistry revealed that microRNA-214 and Slit-Robo GTPase-activating protein 3 were co-localized in dorsal root ganglion primary neu-rons. Western blot analysis suggested that Slit-Robo GTPase-activating protein 3 was upregulated in dorsal root ganglion neurons after sciatic nerve transection. These data demonstrate that mi-croRNA-214 is located and differentially expressed in dorsal root ganglion primary neurons and may participate in regulating the gene expression of Slit-Robo GTPase-activating protein 3 after sciatic nerve transection.

Biological characteristics of dynamic expression of nerve regeneration related growth factors in dorsal root ganglia after peripheral nerve injury

The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regeneration.Our previous study observed the dynamic changes of genes in L4–6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing.Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3,9 hours,1,4,or 7 days after nerve crush,compared with the 0 hour control.Thirty-six rat models of sciatic nerve crush injury were prepared as described previously.Then,they were divided into six groups to measure the expression changes of representative genes at 0,3,9 hours,1,4 or 7 days post crush.Our current study measured the expression levels of representative upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin genes,and explored critical signaling pathways and biological process through bioinformatic analysis.Our data revealed that many of these dysregulated upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin,participated in tissue remodeling and axon growth-related biological processes Therefore,the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury.Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves.All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals,China(approval No.20170302-017)on March 2,2017.

Transcription factor networks involved in cell death in the dorsal root ganglia following peripheral nerve injury

The peripheral nervous system has the potential to regenerate after nerve injury owing to the intrinsic regrowth ability of neurons and the permissive microenvironment.The regenerative process involves numerous gene expression changes,in which transcription factors play a critical role.Previously,we profiled dysregulated genes in dorsal root ganglion neurons at different time points（0,3 and 9 hours,and 1,4 and 7 days） after sciatic nerve injury in rats by RNA sequencing.In the present study,we investigated differentially expressed transcription factors following nerve injury,and we identified enriched molecular and cellular functions of these transcription factors by Ingenuity Pathway Analysis.This analysis revealed the dynamic changes in the expression of transcription factors involved in cell death at different time points following sciatic nerve injury.In addition,we constructed regulatory networks of the differentially expressed transcription factors in cell death and identified some key transcription factors（such as STAT1,JUN,MYC and IRF7）.We confirmed the changes in expression of some key transcription factors（STAT1 and IRF7） by quantitative reverse transcription-polymerase chain reaction.Collectively,our analyses provide a global overview of transcription factor changes in dorsal root ganglia after sciatic nerve injury and offer insight into the regulatory transcription factor networks involved in cell death.

Na_v1.7 protein and mRNA expression in the dorsal root ganglia of rats with chronic neuropathic pain

Neuropathic pain was produced by chronic constriction injury of the sciatic nerve in rats. Behaviora tests showed that the thresholds for thermal and mechanical hyperalgesia were significantly reduced in neuropathic pain rats 3 28 days following model induction. The results of immunohistochemistry, western blot assays and reverse transcription-PCR showed that Nay1.7 protein and mRNA expression was significantly increased in the injured dorsal root ganglia. These findings indicated that Nay1.7 might play an important role in the model of chronic neuropathic pain

Prokaryotic expression of recombinant human p75NTR-Fc fusion protein and its effect on the neurite outgrowth of dorsal root ganglia neuron

Objective： To clone, express, and identify the extracellular domain gene of human p75 neurotrophin receptor with IgG-Fe （hp75NTR-Fc） in prokaryotic expression system, and investigate the effect of the recombinant protein on dorsal root ganglia （DRG） neuron neurites. Methods： The hp75NTR-Fc coding sequence was amplified from pcDNA-hp75NTR-Fc by polymerase chain reaction （PCR） and subcloned into vector pET30a （＋）, in which hp75NTR-Fc expression was controlled under the T7 promoter. The recombinant vectors were amplified in E. coli DH5α and identified by PCR, enzyme digestion and sequencing, and then transformed into E. coli BL21 （DE3）. The expression product was analyzed with SDS-PAGE and Western blot. Then after the recombinant protein purified with Protein A affinity chromatograph, and renaturated with dialysis, respectively, the effect of the recombinant protein on DRG neuron neuritis was further investigated. Results： The results of PCR, enzyme digestion, and sequencing demonstrated the success of inserting the hp75NTR-Fc fragment into vector pET30a （＋）. SDS-PAGE and Western blot showed a positive protein band with molecular weight about 50 kD in the expression product, which is accordant with the interest protein, and this band could be specifically recognized by rabbit anti-NGFRp75 antibody. The purified infusion protein following dialysis could promote neurite outgrowth of DRG neurons cultured with myelin-associated glycoprotein （MAG）. Conclusion： The hp75NTR-Fc coding sequence was subcloned into the expression vector pET30a （＋） correctly and expressed successfully in the prokaryotie expression system. The infusion protein could promote neurite outgrowth of DRG neurons cultured with MAG.

Pain-related mediators underlie incision-induced mechanical nociception in the dorsal root ganglia

Approximately 50-70% of patients experience incision-induced mechanical nociception after sur- gery. However, the mechanism underlying incision-induced mechanical nociception is still unclear. Interleukin-10 and brain-derived neurotrophic factor are important pain mediators, but whether in- terleukin-10 and brain-derived neurotrophic factor are involved in incision-induced mechanical no- ciception remains uncertain. In this study, forty rats were divided randomly into the incision surgery （n = 32） and sham surgery （n = 8） groups. Plantar incision on the central part of left hind paw was performed under anesthesia in rats from the surgery group. Rats in the sham surgery group re- ceived anesthesia, but not an incision. Yon Frey test results showed that, compared with the sham surgery group, incision surgery decreased the withdrawal threshold of rats at 0.5, 3, 6 and 24 hours after incision. Immunofluorescence staining in the dorsal root ganglia of the spinal cord （L3-5） showed that interleukin-10 and brain-derived neurotrophic factor were expressed mainly on small- and medium-sized neurons （diameter 〈 20 pm and 20-40 pm） and satellite cells in the dorsal root ganglia of the spinal cord （L3-5） in the sham surgery group. By contrast, in the surgery group, high expression of interleukin-10 and brain-derived neurotrophic factor appeared in large-sized neurons （diameter 〉 40 pm） at 6 and 24 hours after incision surgery, which corresponded to the decreased mechanical withdrawal threshold of rats in the surgery group. These experimental findings suggest that expression pattern shift of interleukin-10 and brain-derived neurotrophic factor induced by inci- sion surgery in dorsal root ganglia of rats was closely involved in lowering the threshold to me- chanical stimulus in the hind paw following incision surgery. Pain-related mediators induced by in- cision surgery in dorsal root ganglia of rats possibly underlie mechanical nociception in ipsilateral hind paws.

Proteome profiling of spinal cord and dorsal root ganglia in rats with trinitrobenzene sulfonic acid-induced colitis

AIM: To investigate proteomic changes in spinal cord and dorsal root ganglia (DRG) of rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis. METHODS: The colonic myeloperoxidase (MPO) activity and tumor necrosis factor-(TNF- ) level were determined. A two-dimensional electrophoresis (2-DE)-based proteomic technique was used to profile the global protein expression changes in the DRG and spinal cord of the rats with acute colitis induced by intracolonic injection of TNBS. RESULTS: TNBS group showed significantly elevated colonic MPO activity and increased TNF-level. The proteins derived from lumbosacral enlargement of the spinal cord and DRG were resolved by 2-DE; and 26 and 19 proteins that displayed significantly different expression levels in the DRG and spinal cord were identified respectively. Altered proteins were found to be involved in a number of biological functions, such as inflammation/immunity, cell signaling, redox regulation, sulfate transport and cellular metabolism. The over-expression of the protein similar to potassium channel tetramerisation domain containing protein 12 (Kctd 12) and low expression of proteasome subunit type-1 (psma) were validated by Western blotting analysis. CONCLUSION: TNBS-induced colitis has a profound impact on protein profiling in the nervous system. This result helps understand the neurological pathogenesis of inflammatory bowel disease.

Increased phosphorylation of cyclic AMP response element binding protein(CREB)in the dorsal root ganglia and superficial dorsal horn neurons following chronic constriction injury

Objective To investigate whether chronic constriction injury(CCI)of the sciatic nerve of rats could produce alterations in the phosphorylation of cyclic AMP response element binding(CREB)protein in dorsal root ganglia(DRG)and superficial dorsal horn neurons of the spinal cord.Methods Chronic constriction injury(CCI)of the sciatic nerve was employed as a model of neuropathic pain.Thirty-two Sprague-Dawley rats were randomly divided into Na⒍ve,Sham,CCI2w(received CCI for2weeks)and CCI4w(received CCI for4weeks)groups.Hind pawwithdrawal threshold to mechanical stimuli and withdrawal latency to thermal stimuli were used to determine the mechanical and thermal hyperalgesia.Then all the rats were deeply anesthetized and perfused intracardially with paraformaldehyde.The fixed L 4-5 spinal cord and the L 5 DRG ipsilateral to CCI were harvested for fixation.The pCREB-immunoreactive(pCREB-IR)cells in both DRG and superficial dorsal horn neurons were quantified for analysis using immunohistochemistry methods.Results On the14th day after sciatic nerve injury,all the rats exhibited significant mechanical and thermal hyperalgesia.The mechanical withdrawal thresholds to von Frey filament from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01);Thermal withdwal latencies from CCI2w group decreased significantly compared to both baseline values and those of Sham group(P<0.01).Some rats from Sham group also showed mechanical hyperalgesia compared to both baseline values and those of Na⒍ve group(P<0.01).28days after CCI,both mechanical and thermal hypersensitivity were significantly alleviated,with no statistical significance compared to those of Sham group.On the14th day after CCI,the number of pCREB-IR cells significantly increased in ipsilateral L 5 DRGs and superficial dorsal horns(P<0.01)compared to Sham group.The number of phosphorylated CREB-IR cells in the ipsilateral DRGs from Sham group also increased compared to that of Naive rats(P<0.05).There were no significant statistical differences of numbers of CREB-IR neuron between Sham group and CCI4wgroup.Conclusion CCI increases CREB phosphorylation both in DRG and superficial dorsal horn neurons of the lumbar spinal cord,and may be one of the key molecular mechanisms of central and peripheral sensitization following peripheral nerve injury.

Dorsal root ganglion-derived Schwann cells combined with poly(lactic-co-glycolic acid)/chitosan conduits for the repair of sciatic nerve defects in rats

Schwann cells, nerve regeneration promoters in peripheral nerve tissue engineering, can be used to repair both the peripheral and central nervous systems. However, isolation and puriifcation of Schwann cells are complicated by contamination with ifbroblasts. Current reported measures are mainly limited by either high cost or complicated procedures with low cell yields or purity. In this study, we collected dorsal root ganglia from neonatal rats from which we obtained highly puriifed Schwann cells using serum-free melanocyte culture medium. The purity of Schwann cells （〉95%） using our method was higher than that using standard medium containing fetal bovine serum. The obtained Schwann cells were implanted into poly（lactic-co-glycolic acid）/chi-tosan conduits to repair 10-mm sciatic nerve defects in rats. Results showed that axonal diameter and area were signiifcantly increased and motor functions were obviously improved in the rat sciatic nerve tissue. Experimental ifndings suggest that serum-free melanocyte culture medium is conducive to purify Schwann cells and poly（lactic-co-glycolic acid）/chitosan nerve conduits combined with Schwann cells contribute to restore sciatic nerve defects.

A novel primary culture method for high-purity satellite glial cells derived from rat dorsal root ganglion

Satellite glial cells surround neurons within dorsal root ganglia. Previous studies have focused on single-cell suspensions of cultured neurons derived from rat dorsal root ganglia. At present, the primary culture method for satellite glial cells derived from rat dorsal root ganglia requires no digestion skill. Hence, the aim of the present study was to establish a novel primary culture method for satellite glial cells derived from dorsal root ganglia. Neonatal rat spine was collected and an incision made to expose the transverse protrusion and remove dorsal root ganglia. Dorsal root ganglia were freed from nerve fibers, connective tissue, and capsule membranes, then rinsed and transferred to 6-well plates, and cultured in a humidified 5% CO_2 incubator at 37°C. After 3 days in culture, some cells had migrated from dorsal root ganglia. After subculture, cells were identified by immunofluorescence labeling for three satellite glial cell-specific markers: glutamine synthetase, glial fibrillary acidic protein, and S100β. Cultured cells expressed glutamine synthetase, glial fibrillary acidic protein, and S100β, suggesting they are satellite glial cells with a purity of > 95%. Thus, we have successfully established a novel primary culture method for obtaining high-purity satellite glial cells from rat dorsal root ganglia without digestion.

Chemokine platelet factor 4 accelerates peripheral nerve regeneration by regulating Schwann cell activation and axon elongation

Schwann cells in peripheral nerves react to traumatic nerve injury by attempting to grow and regenerate.Howeve r,it is unclear what factors play a role in this process.In this study,we searched a GEO database and found that expression of platelet factor 4 was markedly up-regulated after sciatic nerve injury.Platelet factor is an important molecule in cell apoptosis,diffe rentiation,survival,and proliferation.Further,polymerase chain reaction and immunohistochemical staining confirmed the change in platelet factor 4 in the sciatic nerve at different time points after injury.Enzyme-linked immunosorbent assay confirmed that platelet factor 4 was secreted by Schwann cells.We also found that silencing platelet factor 4 decreased the proliferation and migration of primary cultured Schwann cells,while exogenously applied platelet factor 4 stimulated Schwann cell prolife ration and migration and neuronal axon growth.Furthermore,knocking out platelet factor 4 inhibited the prolife ration of Schwann cells in injured rat sciatic nerve.These findings suggest that Schwann cell-secreted platelet factor 4 may facilitate peripheral nerve repair and regeneration by regulating Schwann cell activation and axon growth.Thus,platelet factor 4 may be a potential therapeutic target for traumatic peripheral nerve injury.

神经病理痛大鼠DRG神经元GABA_A受体激活电流的变化

目的:观察坐骨神经慢性压榨损伤(CCI)致神经病理痛后,大鼠背根节神经元GABAA受体(γ-氨基丁酸A受体)激活电流的变化。方法:运用全细胞膜片钳技术记录CCI模型手术侧、手术对侧及假手术组大鼠背根神经节细胞GABAA受体激活电流,比较坐骨神经慢性压榨损伤后GABAA受体激活电流的变化。结果:①CCI模型组大鼠手术侧DRG神经元在不同浓度(0.1-1000μmol/L)GABAA受体激活电流幅值均显著小于假手术组。②CCI模型组大鼠手术对侧DRG神经元在不同浓度(0.01-1000μmol/L)GABAA受体激活电流幅值均显著大于手术同侧及假手术组。结论:在坐骨神经慢性压榨损伤的过程中,不仅损伤侧的DRG神经元GABAA受体激活电流显著减小,这种损伤同时还引起了手术对侧的DRG神经元GABA激活电流代偿性的增强,GABAA受体功能的改变导致的突触前抑制作用的减弱可能是神经病理痛产生的根本原因之一。

咪达唑仑对神经病理性痛大鼠DRG神经元GABA-AR激活电流的增强作用

目的:观察大鼠坐骨神经慢性压迫性损伤(chronic constriction injury CCI)致神经病理性痛后,咪达唑仑对背根神经节(dorsal root ganglion,DRG)神经元上γ-氨基丁酸A受体(gamma-aminobutyricacid A receptor,GABA-AR)激活电流的调控作用。方法:运用全细胞膜片钳技术,记录假手术、CCI组、正常组GABA-AR激活电流的变化、以及咪达唑仑对坐骨神经慢性压迫性损伤后GABA-AR激活电流的影响。结果:CCI组GABA(0.1～1000μmol/L)激活的电流幅值显著小于假手术组和正常组。假手术组和正常组由GABA(0.1～1000μmol/L)激活的电流幅值差异无统计学意义。不同浓度咪达唑仑(0.03～100μmol/L)对CCI组GABA-AR激活电流均有增强作用,且随咪达唑仑浓度升高,对DRG神经元GABA-AR激活电流的增强率逐渐升高,3.00μmol/L咪达唑仑时达峰值(P<0.05或0.01)。结论:在CCI组中,DRG神经元GABA-AR功能的改变导致的突触前抑制作用的减弱可能是疼痛产生的关键因素之一。咪达唑仑对CCI组GABA-AR功能有增强作用,增强GABA-AR参与突触前抑制作用,可能是其在脊髓水平产生镇痛的机制之一。

罗哌卡因对大鼠DRG神经元GABA_A受体激活电流的影响

目的：研究罗哌卡因对大鼠背根神经节（DRG）神经元γ-氨基丁酸（GABA）介导膜电流的作用,探讨罗哌卡因的镇痛机理。方法：采用全细胞膜片钳技术,观察预灌流罗哌卡因对急性新鲜分离大鼠DRG神经元GABA激活电流（IGABA）的调制作用。结果：①在受检的73个DRG神经元中大多数（65.7%,48/73）对灌流罗哌卡因（0.1~1 000μmol/L）敏感。产生一幅值在0~380 pA具有浓度依赖性的内向电流。②实验中大部分受检细胞（74.5%,73/98）对外加的GABA敏感。浓度为0.1~1 000μmol/LGABA可引起具有剂量依赖性和明显去敏感作用的内向电流,并且这种内向电流能被GABAA受体选择性拮抗剂bicuculline（100μmol/L）所阻断。③预灌流罗哌卡因（0.1~1 000μmol/L）30 s后再灌流GABA能显著增强GABA（100μmol/L）激活电流的幅值。预加罗哌卡因后GABA量效曲线明显上移,EC50为23.46μmol/L;GABA激活电流的最大值较之对照增强约153%。结论：罗哌卡因对DRG神经元GABA激活电流的增强作用,可导致突触前抑制作用增强,这可能是罗哌卡因在硬膜外麻醉中产生镇痛和麻醉作用的原因之一。

舒芬太尼对大鼠DRG神经元GABA_A激活电流的增强作用

目的:观察不同浓度舒芬太尼对大鼠背根神经节细胞GABAA激活电流(GABA-activated current,IGABA)的调控作用。方法 :在急性分离的大鼠背根神经节细胞上,应用全细胞膜片钳技术记录预加0.02、0.1、0.5、2.5μmol/L的舒芬太尼,以及非特异性阿片受体拮抗剂纳洛酮1 nmol/L+0.5μmol/L舒芬太尼对IGABA的影响。结果:0.02、0.1、0.5、2.5μmol/L舒芬太尼将IGABA分别增强到(108.7±6.7)%、(122.0±2.3)%、(146.7±7.9)%、(130.1±5.6)%(n=10;*P<0.05,觹觹P<0.01)。0.1、0.5、2.5μmol/L舒芬太尼对IGABA的增强作用在撤药后12、18、12 min消失(n=10;觹P<0.05,觹觹P<0.01),且舒芬太尼样受体增强IGABA作用可被1nmol/L纳洛酮部分阻断(n=7;觹P<0.05,觹觹P<0.01)。结论 :舒芬太尼激活μ阿片样受体增强IGABA,并可部分被纳洛酮拮抗,舒芬太尼增强GABAA受体的脊髓突触前抑制可能是其在脊髓水平产生镇痛作用的机制之一。

2,5-HD对大鼠DRG神经元神经丝蛋白表达的影响

目的比较2,5-己二酮(2,5-HD)和3,3′-亚氨基二丙腈(3,3-′IDPN)对大鼠DRG神经元神经丝蛋白(NF-M)的损伤作用。方法用出生后2 d的大鼠背根神经节(DRG)神经元,在培养皿中加不同浓度的2,5-HD和3,3-′IDPN进行培养,用荧光染料测定细胞毒性,计算细胞死亡率。用蛋白免疫荧光方法测定NF-M,计算DRG神经元细胞体的神经丝表达。结果DRG神经元24 h接触2,5-HD和3,3-′IDPN的LD50约为32和102 mmol/L。DRG细胞体内的NF-M蛋白含量在接触2,5-HD(0、4、8和16 mmo/L浓度)24和48 h后结果显示,各个剂量组均有明显降低(P<0.05,P<0.01);而在接触3,3-′IDPN 24 h后,各个剂量组之间没有发生明显改变,但在接触48 h后,仅有64,128 mmol/L组与对照相比,差异有统计学意义(P<0.05,P<0.01)。在DRG神经元具有相同死亡率时,2,5-HD和3,3-I′DPN 24 h后对NF-M蛋白表达差异有统计学意义(P<0.05)。结论2,5-HD与3,3-′IDPN对NF-M的损伤不同。2,5-HD减少NF-M蛋白表达要早于细胞死亡。NF-M对2,5-HD比对3,3-′IDPN敏感。

6-羟多巴胺通过p38 MAPK信号通路诱发大鼠机械痛敏反应

目的:研究p38 MAPK信号通路参与6-羟多巴胺(6-OHDA)诱导的帕金森病(PD)模型大鼠痛敏反应的调节机制。方法:将40只雄性Sprague Dawley(SD)大鼠随机分为4组:假手术组(Sham)、模型组(6-OHDA)、p38 MAPK抑制剂SB203580处理组(6-OHDA+SB203580)、p38 MAPK激动剂茴香霉素(ANS)处理组(6-OHDA+ANS)。采用脑内右侧纹状体立体定向注射6-OHDA的方法建立大鼠PD模型。6-OHDA+SB203580组与6-OHDA+ANS组大鼠注射6-OHDA构建PD模型后分别注射SB203580与ANS进行处理。von Frey纤维丝测痛仪测定大鼠机械缩足阈值(PWT);酶联免疫吸附测定(ELISA)法检测大鼠背根神经节(DRG)中IL-6、IL-1β、TNF-α的含量;real time RT-PCR检测大鼠DRG中IL-6、IL-1β、TNF-α及p38 MAPK的mRNA水平。结果:在6-OHDA诱导的PD模型大鼠DRG中,IL-6、IL-1β、TNF-α和p38 MAPK的表达水平显著升高(P<0.05),大鼠PWT显著下降(P<0.05);而应用激动剂ANS会更进一步地导致大鼠DRG中IL-6、IL-1β、TNF-α和p38 MAPK的表达水平升高,并使大鼠PWT降低;应用抑制剂SB203580后大鼠DRG中IL-6、IL-1β、TNF-α和p38 MAPK的表达水平均显著降低(P<0.05),大鼠PWT显著升高(P<0.05)。结论:6-OHDA可诱导大鼠产生机械性痛敏反应,其分子机制与p38 MAPK信号通路激活有关。

大鼠慢性背根节压迫诱致DRG大神经元兴奋性增强和Ih电流显著上调

目的:探讨大鼠CCD模型模拟的腰背痛诱致的DRG大神经元兴奋性改变及其离子通道机制。方法:建立大鼠慢性压迫腰膨大L4/L5 DRG的CCD模型,模拟临床常见的腰背痛的触诱发痛表现。制备整节L4/L5 DRG标本,应用全细胞膜片钳技术记录去极化电流刺激诱致的DRG大型神经元的兴奋性改变及其离子通道机制。结果:对直径>50μm的健康的DRG大神经元进行全细胞膜片钳记录。结果显示:给予去极化方波电流刺激可以诱致CCD模型大鼠DRG大神经元呈现兴奋性增强的表现,具体表现为相同刺激强度的电流注射在CCD模型DRG大神经元上诱致的动作电位的频率显著高于对照组神经元。同样的细胞放电增强也见于给予细胞斜波电流刺激。进一步的机制研究分析显示CCD模型大鼠上DRG大神经元的I_h电流明显高于对照组大鼠。结论:CCD模型可以诱致DRG大神经元呈现超兴奋状态,该兴奋性增强的状态主要由I_h电流增强来介导,为认识神经损伤诱致的病理性痛觉敏化尤其是触诱发痛的神经机制提供了实验证据。