Drebrin在坐骨神经慢性压迫性损伤大鼠远位触液神经元的表达

为观察坐骨神经慢性压迫性损伤(chronic constriction injury,CCI)后大鼠远位触液神经元(distal cerebrospinal fluid con-tacting neurons,dCSF-CNs)中drebrin的表达,探讨免疫荧光技术用于dCSF-CNs研究的可能性,将雄性Sprague-Dawley大鼠随机分为空白对照组、假手术组和CCI组,采用侧脑室注射霍乱毒素亚单位B(choleratoxin subunit B,CB)与辣根过氧化物酶(horseradish peroxidase,HRP)结合物(CB-HRP)示踪标记大鼠dCSF-CNs,观测三组大鼠行为学评分,并应用免疫荧光双标记和激光共聚焦显微镜技术比较各组dCSF-CNs中drebrin的表达.结果显示,三组中仅CCI组大鼠痛阈下降,三组大鼠dCSF-CNs均显示清晰,空白对照组和假手术组dCSF-CNs胞浆内无drebrin表达,CCI组dCSF-CNs胞浆内drebrin表达较多.结果表明,应用免疫荧光双标记观察dCSF-CNs,形态清晰,技术可靠.dCSF-CNs可能参与了神经病理性疼痛的信息传递.     

cAMP反应元件结合蛋白介导磷酸化细胞外信号调节激酶在神经病理性痛形成中的作用

采用行为学、免疫组织化学和Western blot方法,观察鞘内注射细胞外信号调节激酶(extracellular signal-regulate kinase,ERK)信号转导通路阻滞剂对慢性压迫性损伤(chronic constriction injury,CCI)大鼠痛行为及脊髓背角内磷酸化cAMP反应元件结合蛋白(phosphorylated cAMP response-element binding protein,pCREB)和Fos表达变化的影响,探讨ERK／CREB转导通路在神经病理性疼痛中的作用。结果表明,CCI可明显增加双侧脊髓背角pCREB、损伤侧脊髓背角浅层Fos阳性神经元表达,以CCI后3与5d时尤为显著。鞘内沣射促分裂原活化蛋白激酶激酶(mitogen-activated protein kinase kinase,MEK)阻滞剂U0126及ERK反义寡核苷酸在减轻大鼠痛行为的同时,能明显抑制双侧脊髓背角内pCREB的表达,同时,Fos阳性神经元的表达也明显减少。大鼠痛行为及脊髓背角pCREB和Fos的表达在时相上一致。上述结果提示pCREB参与pERK介导的神经病理性疼痛。     

脊髓p38丝裂原活化蛋白激酶激活参与坐骨神经压迫性损伤所致神经病理性痛

本研究旨在观察脊髓p38丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase,p38 MAPK）在坐骨神经压迫性损伤所致神经病理性痛中的作用。雄性Sprague-Dawley大鼠鞘内置管后,4-0丝线松结扎左侧坐骨神经制作慢性压迫性损伤（chronic constriction injury,CCI）模型。CCI后第5天,鞘内注射不同剂量的p38 MAPK特异性抑制剂SB203580,并在给药前及给药后不同时间点,分别用von Frey机械痛敏监测仪和热辐射刺激仪监测大鼠损伤侧后爪机械和热刺激反应闽值,用免疫印迹技术（Western blot）观察给药前后脊髓磷酸化p38 MAPK（p-p38 MAPK）和磷酸化环磷酸腺苷反应元件结合蛋白（phosphorylated cAMP response element binding protein,pCREB）表达变化。结果发现：坐骨神经压迫性损伤引起脊髓p-p38 MAPK蛋白表达明显增加;鞘内注射SB203580能剂量依赖性逆转CCI引起的机械性痛觉异常和热痛觉过敏及脊髓水平p-p38 MAPK表达的增加,也明显抑制CCI引起的脊髓pCREB表达的增加。结果提示,脊髓水平p38 MAPK激活参与坐骨神经压迫性损伤所致神经病理性痛的发展,其作用可能通过pCREB介导。     

Proteomic analysis of differential protein expression in neuropathic pain and electroacupuncture treatment models

Acupuncture has long been used for pain relief. Although recent studies have shown that acupuncture can reduce neuropathic pain, the mechanism of this effect is not clear and little information is available regarding proteins that are involved in the development of neuropathic pain and the effects of acupuncture. We have developed an animal model for neuropathic pain using young adult male Sprague-Dawley rats. The model was confirmed by behavioral tests. Electroacupuncture (EA) treatment was applied to Zusanli (ST36) of neuropathic pain model to examine the analgesic effect of EA. The protein expression profile of the hypothalamus in both neuropathic pain and EA treatment models was analyzed using two-dimensional electrophoresis-based proteomics. We detected thirty-six proteins that were differentially expressed in the neuropathic pain model compared with normal rats and that restored to normal expression levels after EA treatment. Twenty-one of these proteins were identified in the MS-FiT database and are involved in a number of biological processes, including inflammation, enzyme metabolism and signal transduction. Potential applications of our results include the identification and characterization of signaling pathways involved in EA treatment and further exploration of the role of selected identified proteins in the animal model.     

Experimental Characterization of the Chronic Constriction Injury-Induced Neuropathic Pain Model in Mice

Number of ligations made in the chronic constriction injury (CCI) neuropathic pain model has raised serious concerns. We compared behavioural responses, nerve morphology and expression of pain marker, c-fos among CCI models developed with one, two, three and four ligations. The numbers of ligation(s) on sciatic nerve shows no significant difference in displaying mechanical and cold allodynia, and mechanical and thermal hyperalgesia throughout 84 days. All groups underwent similar levels of nerve degeneration post-surgery. Similar c-fos level in brain cingulate cortex, parafascicular nuclei and amygdala were observed in all CCI models compared to sham-operated group. Therefore, number of ligations does not impact intensity of pain symptoms, pathogenesis and neuronal activation. A single ligation is sufficient to develop neuropathic pain, in contrast to the established model of four ligations. This study dissects and characterises the CCI model, ascertaining a more uniform animal model to surrogate actual neuropathic pain condition.

     

Role of IL‐15 in spinal cord and sciatic nerve after chronic constriction injury: regulation of macrophage and T‐cell infiltration

The release of inflammatory mediators from immune and glial cells either in the peripheral or CNS may have an important role in the development of physiopathological processes such as neuropathic pain. Microglial, then astrocytic activation in the spinal cord, lead to chronic inflammation, alteration of neuronal physiology and neuropathic pain. Standard experimental models of neuropathic pain include an important peripheral inflammatory component, which involves prominent immune cell activation and infiltration. Among potential immunomodulators, the T‐cell cytokine interleukin‐15 (IL‐15) has a key role in regulating immune cell activation and glial reactivity after CNS injury. Here we show, using the model of chronic constriction of the sciatic nerve (CCI), that IL‐15 is essential for the development of the early inflammatory events in the spinal cord after a peripheral lesion that generates neuropathic pain. IL‐15 expression in the spinal cord was identified in both astroglial and microglial cells and was present during the initial gliotic and inflammatory (NFκB) response to injury. The expression of IL‐15 was also identified as a cue for macrophage and T‐cell activation and infiltration in the sciatic nerve, as shown by intraneural injection of the cytokine and activity blockage approaches. We conclude that the regulation of IL‐15 and hence the initial events following its expression after peripheral nerve injury could have a future therapeutic potential in the reduction of neuroinflammation.     

Proteomics of the injured rat sciatic nerve reveals protein expression dynamics during regeneration

Using proteomics, we investigated the temporal expression profiles of proteins in rat sciatic nerve after experimental crush. Extracts of sciatic nerves collected at 5, 10, and 35 days after injury were analyzed by two-dimensional gel electrophoresis and quantitative image analysis. Of the approximately 1,500 protein spots resolved on each gel, 121 showed significant regulation during at least one time point. Using cluster analysis, these proteins were grouped into two expression profiles of down-regulation and four of up-regulation. These profiles mainly reflected differences in cellular origins in addition to different functional roles. Mass spectrometric analysis identified 82 proteins pertaining to several functional classes, i.e. acute-phase proteins, antioxidant proteins, and proteins involved in protein synthesis/maturation/degradation, cytoskeletal (re)organization, and in lipid metabolism. Several proteins not previously implicated in nerve regeneration were identified, e.g. translationally controlled tumor protein, annexin A9/31, vitamin D-binding protein, alpha-crystallin B, alpha-synuclein, dimethylargininases, and reticulocalbin. Real-time PCR analysis of selected genes showed which were expressed in the nerve versus the dorsal root ganglion neurons. In conclusion, this study highlights the complexity and temporal aspect of the molecular process underlying nerve regeneration and points to the importance of glial and inflammatory determinants.     

姜黄素下调脊髓Toll样受体4及下游细胞因子减弱大鼠神经病理性痛

观察鞘内注射姜黄素对坐骨神经慢性压迫性损伤(CCI)大鼠痛阈和脊髓组织Toll样受体4(TLR4)及TNF-α、IL-1β和IL-10表达的影响．鞘内置管的120只大鼠随机均分为4组：假手术组(Sham),CCI组,溶剂对照组(SC),姜黄素治疗组(Cur,100 μg/天),建立CCI大鼠疼痛模型,术后第1、3、7、10和14天鞘内给药并测定痛阈,第3、7天取腰段脊髓第4～6节段(L4～L6)以Real-time PCR与Western blotting方法检测TLR4、HMGB1 mRNA和蛋白质的表达,ELISA法观察脊髓组织中TNF-α、IL-1β及IL-10表达变化．与Sham组相比,CCI组大鼠机械性痛阈与热痛阈显著降低(均P<0.05),同时脊髓组织TLR4、HMGB1 mRNA和蛋白质的表达明显增加(均P<0.05),TNF-α、IL-1β与IL-10的含量也明显升高(均P<0.05);鞘内注射姜黄素明显降低脊髓TLR4、高迁移率族蛋白1(HMGB1),TNF-α和IL-1β的表达,显著升高脊髓IL-10的表达,同时明显改善CCI大鼠疼痛行为(P<0.05)．姜黄素减轻神经病理性疼痛可能与下调TLR4途径促炎症因子表达有关,抑制TLR4途径有望成为治疗神经病理性疼痛的新策略．     

Differential Regulation of Glucocorticoid Receptor Expression in Distinct Columns of Periaqueductal Grey in Rats with Behavioural Disability Following Nerve Injury

Neuropathic pain is diagnosed primarily by sensory dysfunction, which includes both spontaneous, and stimulus-evoked pain. Clinical evaluation highlights the disabilities which characterise this condition for most patients. Chronic constriction injury of the sciatic nerve (CCI) evokes sensory dysfunction characteristic of neuropathic pain. Approximately, 30 % of CCI rats show disabilities similar to those identified in clinical evaluation of neuropathic pain patients, these include: altered social behaviours; sleep disturbances; and endocrine dysfunction. The periaqueductal grey (PAG) is a nodal point in the brain circuits which regulate these functions, and undergoes a distinct set of neural and glial adaptations following CCI, in rats with disabilities. CCI increases corticosterone, which through its actions at the glucocorticoid receptor (GR), can trigger cellular adaptation. GR expression in PAG was quantified using qRT-PCR, Western blotting and immunohistochemical analyses and nerve-injured rats, with and without disabilities, were compared. Our data showed that the PAG of disabled rats has significantly increased expression of GR mRNA and protein. Further, this increased protein expression reflects contrasting patterns of change in GR expression in PAG subregions. The dorsolateral PAG had significant increases in the number of GR-immunoreactive (GR-IR) cells and the caudal lateral and ventrolateral PAG each had significant reductions in the number of GR-IR cells. These regional increases and decreases correlated with the degree of disability, as indicated by the degree of change in social behaviours. Our results suggest a role for altered PAG, GR–corticosterone interactions and their resultant cellular consequences in the expression of disabilities in a subpopulation of nerve-injured rats.     

Upregulation of miR-183 represses neuropathic pain through inhibiton of MAP3K4 in CCI rat models

Many studies have verified that microRNAs contribute a lot to neuropathic pain progression. Furthermore, nerve-related inflammatory cytokines play vital roles in neuropathic pain progression. miR-183 has been identified to have a common relationship with multiple pathological diseases. However, the potential effects of miR-183 in the process of neuropathic pain remain undetermined. Therefore, we performed the current study with the purpose of finding the functions of miR-183 in neuropathic pain progression using a chronic sciatic nerve injury (CCI) rat model. We demonstrated that miR-183 expression levels were evidently reduced in CCI rats in contrast with the control group. Overexpression of miR-183 produced significant relief of mechanical hyperalgesia, as well as thermal hyperalgesia in CCI rats. Furthermore, neuropathic pain-correlated inflammatory cytokine expression levels containing interleukin-6 (IL-6) and interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2) were obviously inhibited by upregulation of miR-183. Meanwhile, dual-luciferase reporter assays showed MAP3K4 was a direct downstream gene of miR-183. The expression levels of MAP3K4 were modulated by the increased miR-183 negatively, which lead to the downregulation of IL-6, IL-1β, and COX-2, and then reduced neuropathic pain progression, respectively. Overall, our study pointed out that miR-183 was a part of the negative regulator which could relieve neuropathic pain by targeting MAP3K4. Thus it may provide a new clinical treatment for neuropathic pain patients clinical therapy.     

不同浓度沙利度胺对大鼠慢性坐骨神经缩窄模型的镇痛效果及机制

目的:比较不同剂量沙利度胺对大鼠慢性坐骨神经缩窄(chronic sciatic nerve constriction,CCI)的镇痛效果及可能机制。方法:将50只大鼠随机分为S组、C组、L组、M组及H组,S组作为假手术组,其余四组建立CCI模型,术后分别用20 mg/kg、50mg/kg、100 mg/kg沙利度胺处理L组、M组、H组。于术后第1、2、3、4周测量和比较各组大鼠机械性痛阈与热痛阈,采用蛋白质印迹法(Western blot)及实时荧光定量PCR(Q-PCR)检测各组大鼠肿瘤坏死因子受体(TNFR)的mRNA和蛋白表达,并分析沙利度胺浓度与TNFR mRNA相对表达的相关性。结果:S组术前术后的机械性痛阈与热痛阈均无明显改变(P0.05),其余四组术后痛阈均较术前明显下降(P0.05);C组术后第4周时机械性痛阈明显升高(P0.05),而术后其他时间点的机械性痛阈与热痛阈无明显差异(P0.05);L组、M组、H组术后机械性痛阈、热痛阈随时间的延长呈上升趋势,差异有统计学意义(P0.05)。术后,C组机械性痛阈与热痛阈对比S组明显降低(P=0.000),亦显著低于L组(P=0.000);而不同剂量组机械性痛阈、热痛阈相比,H组高于M组(P=0.000),M组高于L组(P=0.000)。相对于C组,L组、M组、H组术后第4周TNFR1 mRNA及蛋白相对含量显著下降(P0.05),其中H组下降最为明显,M组次之。Pearson相关性分析结果显示:沙利度胺浓度的增加与TNFR1表达水平的升高呈明显负相关关系(r=-0.497,P=0.036)。结论:沙利度胺可能通过影响TNFR表达水平对大鼠慢性坐骨神经缩窄发挥镇痛效应,其镇痛效应随剂量增加而加强,有望作为神经病理性疼痛的辅助镇痛药物之一。     

miR-98 acts as an inhibitor in chronic constriction injury-induced neuropathic pain via downregulation of high-mobility group AT-hook 2

Neuropathic pain, resulting from somatosensory nervous system dysfunction, remains a serious public health problem worldwide. microRNAs are involved in the physiological processes of neuropathic pain. However, the biological roles of miR-98 in neuropathic pain development have not been investigated. Therefore, in our current study, we focused on the effects of miR-98 in neuropathic pain. It was shown that miR-98 was significantly downregulated in chronic sciatic nerve injury (CCI) rat models. In addition, high mobility group A2 (HMGA2) was obviously upregulated in CCI rats. Overexpression of miR-98 inhibited neuropathic pain progression, including mechanical and thermal hyperalgesia. By a bioinformatics analysis, HMGA2 was predicted as a direct target of miR-98. The negative correlation between miR-98 and HMGA2 was validated in our present study. Furthermore, overexpression of miR-98 dramatically repressed HMGA2 protein and messenger RNA (mRNA) expression. Neuroinflammation participates in neural-immune interactions, which can contribute to the neuropathic pain development. Meanwhile, we found that inflammatory cytokine (interleukin [IL]-6, IL-1β, and COX-2) protein expression in rats infected with LV-miR-98 was greatly suppressed. Taking these results together, we concluded that miR-98 might depress neuropathic pain development through modulating HMGA2.     

Antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain

The synthetic peptide identical to the C-terminus of murine S100A9 protein (mS100A9p) has antinociceptive effect on different acute inflammatory pain models. In this study, the effect of mS100A9p was investigated on neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Hyperalgesia, allodynia, and spontaneous pain were assessed to evaluate nociception. These three signs were detected as early as 2 days after sciatic nerve constriction and lasted for over 14 days after CCI. Rats were treated with different doses of mS100A9p by intraplantar, oral, or intrathecal routes on day 14 after CCI, and nociception was evaluated 1h later. These three routes of administration blocked hyperalgesia, allodynia and spontaneous pain. The duration of the effect of mS100A9p depends on the route used and phenomenon analyzed. Moreover, intraplantar injection of mS100A9p in the contralateral paw inhibited the hyperalgesia on day 14 days after CCI. The results obtained herein demonstrate the antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain, suggesting a potential therapeutic use for it in persistent pain syndromes, assuming that tolerance does not develop to mS100A9p.     

不同频率电针刺激对神经痛模型大鼠脊髓背角P物质的影响

目的:观察P物质(Substance P,SP)在慢性坐骨神经压迫损伤(chronic constriction injury,CCI)模型脊髓中表达的变化,探讨电针镇痛的机制是否与脊髓背角中SP表达的变化有关。方法:选择32只雄性、体重180-200 g的SD大鼠,并将其随机均分为4组(n=8)。空白组(Con组)为正常痛阈值大鼠;假电针组(CCI+A组)在损伤的坐骨神经旁置入电针,但无电流刺激;2 Hz组和100Hz组分别给予相应频率电流刺激30 min。在实验开始前和术后1、4、7、14、20、22天记录大鼠的热缩足反射潜伏期(Paw Withdrawal Latency,PWL)和机械刺激缩足反射阈值(Paw Withdrawal Threshold,PWT)。免疫组化方法检测脊髓背角SP的表达。结果:术后20天,电针治疗后,100 Hz组和2 Hz组PWT分别为(7.33±1.42)g和(7.80±1.42)g,均显著高于假电针组(2.60±1.46)g,差异有统计学意义(P0.05)。100 Hz组在术后20天后和2 Hz组在术后14天后PWL值均显著高于假电针组,差异有统计学意义(P0.05)。免疫组化显示:2 Hz组和100 Hz组大鼠脊髓背角中P物质阳性细胞显著低于假电针组(P0.05)。结论:坐骨神经旁电针刺激能够显著减轻CCI模型大鼠热痛觉及机械痛觉过敏,其机制可能与抑制脊髓背角SP的表达有关。     

MiR-183-5p Alleviates Chronic Constriction Injury-Induced Neuropathic Pain Through Inhibition of TREK-1

MicroRNAs have been implicated in nerve injury and neuropathic pain. In the previous study we had shown that miR-96 can attenuate neuropathic pain through inhibition of Nav1.3. In this study, we investigated the role of miR-183, a same cluster member of microRNA with miR-96, in neuropathic pain and its potential mechanisms. We found that the expression level of miR-183-5p in dorsal root ganglion was decreased with the development of neuropathic pain induced by chronic constriction sciatic nerve injury (CCI). By contrast, the TREK-1, a K⁺ channel, was increased. Further investigation identified that intrathecal injection of miR-183-5p mimic efficiently ameliorated neuropathic pain and inhibited the expression of TREK-1, a predicted target gene of miR-183-5p. Luciferase assays confirmed the binding of miR-183-5p and TREK-1. In addition, over-expression of TREK-1 blocked the roles of miR-183-5p in neuropathic pain. Our findings suggested that miR-183-5P participated in the regulation of CCI-induced neuropathic pain through inhibiting the expression of TREK-1.     

Assessment of Oxidative Parameters in Rat Spinal Cord After Chronic Constriction of the Sciatic Nerve

Although reactive oxygen species (ROS) are involved in neuropathic pain, the direct relationship between these species and chronic constriction of sciatic nerve (CCI) has not been studied in spinal cord. Thus, this study induced CCI in rats and these animals were sacrificed 3 and 10?days after the surgical procedure to determine the superoxide dismutase (SOD) and catalase activities, as well as ascorbic acid, hydrogen peroxide (H(2)O(2)) and lipid hydroperoxide levels in lumbosacral spinal cord. Von Frey Hair and hot plate tests were performed to assess the degree of mechanical and thermal hyperalgesia at days 0, 3 and 10. The results showed that CCI significantly induced mechanical and thermal hyperalgesia at days 3 and 10. Parallel there was increase in spinal cord lipid hydroperoxide at days 3 and 10 in rats submitted to CCI. In Sham rats a significant increase in this parameter occurred at day 10. H(2)O(2) decreased at day 10 only in CCI group. SOD activity was decreased in Sham and CCI groups at day 3, while catalase activity was increased in CCI rats at days 3 and 10. Ascorbic acid levels were reduced only in CCI rats at day 3. Although the role of such changes is unclear, many were not specific to neuropathic pain and the differences could be related to different degrees of central sensitization in Sham and CCI rats.