The effects of claudin 14 during early Wallerian degeneration after sciatic nerve injury

Claudin 14 has been shown to promote nerve repair and regeneration in the early stages of Wallerian degeneration （0-4 days） in rats with sciatic nerve injury, but the mechanism underlying this process remains poorly understood. This study reported the effects of claudin 14 on nerve degeneration and regeneration during early Wallerian degeneration. Claudin 14 expression was up-regulated in sciatic nerve 4 days after Wallerian degeneration. The altered expression of claudin 14 in Schwann cells resulted in expression changes of cytokines in vitro. Expression of claudin 14 affected c-Jun, but not Akt anal ERK1/2 patl^ways, l^urther studies reve^ed that enhanced expression of claudin 14 could promote Schwann cell proliferation and migration. Silencing of claudin 14 expression resulted in Schwann cell apoptosis and reduction in Schwann cell proliferation. Our data revealed the role of claudin 14 in early Wallerian degeneration, which may provide new insights into the molecular mechanisms of Wallerian degeneration.

Differential gene expression in proximal and distal nerve segments of rats with sciatic nerve injury during Wallerian degeneration

Wallerian degeneration is a subject of major interest in neuroscience. A large number of genes are differentially regulated during the distinct stages of Wallerian degeneration： transcription factor activation, immune response, myelin cell differentiation and dedifferentiation. Although gene expression responses in the distal segment of the sciatic nerve after peripheral nerve injury are known, differences in gene expression between the proximal and distal segments remain unclear. In the present study in rats, we used microarrays to analyze changes in gene expression, biological processes and signaling pathways in the proximal and distal segments of sciatic nerves under- going Wallerian degeneration. More than 6,000 genes were differentially expressed and 20 types of expression tendencies were identified, mainly between proximal and distal segments at 7-14 days after injury. The differentially expressed genes were those involved in cell differentiation, cytokinesis, neuron differentiation, nerve development and axon regeneration. Furthermore, 11 biological processes were represented, related to responses to stimuli, cell apoptosis, inflammato- ry response, immune response, signal transduction, protein kinase activity, and cell proliferation. Using real-time quantitative PCR, western blot analysis and immunohistochemistry, microarray data were verified for four genes： aquaporin-4, interleukin 1 receptor-like 1, matrix metallopro- teinase-12 and periaxin. Our study identifies differential gene expression in the proximal and distal segments of a nerve during Wallerian degeneration, analyzes dynamic biological changes of these genes, and provides a useful platform for the detailed study of nerve injury and repair during Wallerian degeneration.

Gene expression profiling of the rat sciatic nerve in early Wallerian degeneration after injury

Wallerian degeneration is an important area of research in modern neuroscience. A large number of genes are differentially regulated in the various stages of Wallerian degeneration, especially during the early response. In this study, we analyzed gene expression in early Wallerian degeneration of the distal nerve stump at 0, 0.5, 1,6, 12 and 24 hours after rat sciatic nerve injury using gene chip microarrays. We screened for differentially-expressed genes and gene expression patterns. We examined the data for Gene Ontology, and explored the Kyoto EncycLopedia of Genes and Genomes Pathway. This allowed us to identify key regulatory factors and recurrent network motifs. We identified 1 546 differentially-expressed genes and 21 distinct patterns ofgene expression in early Wallerian degeneration, and an enrichment of genes associated with the immune response, acute inflammation, apoptosis, cell adhesion, ion transport and the extracellular matrix. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed components involved in the Jak-STAT, ErbB, transforming growth factor-13, T cell receptor and calcium signaling pathways. Key factors included interleukin-6, interleukin-1, integrin, c-sarcoma, carcinoembryonic antigen-related cell adhesion molecules, chemokine （C-C motif） ligand, matrix metalloproteinase, BH3 interacting domain death agonist, baculoviral lAP repeat-containing 3 and Rac. The data were validated with real-time quantitative PCR. This study provides a global view of gene expression profiles in eady Wallerian degeneration of the rat sciatic nerve. Our findings provide insight into the molecular mechanisms underlying early Wallerian degeneration, and the regulation of nerve degeneration and regeneration.

Baculoviral inhibitor of apoptosis protein repeatcontaining protein 3 delays early Wallerian degeneration after sciatic nerve injury

Wallerian degeneration is a complex biological process that occurs after nerve injury,and involves nerve degeneration and regeneration.Schwann cells play a crucial role in the cellular and molecular events of Wallerian degeneration of the peripheral nervous system.However,Wallerian degeneration regulating nerve injury and repair remains largely unknown,especially the early response.We have previously reported some key regulators of Wallerian degeneration after sciatic nerve injury.Baculoviral inhibitor of apoptosis protein repeat-containing protein 3(BIRC3)is an important factor that regulates apoptosis-inhibiting protein.In this study,we established rat models of right sciatic nerve injury.In vitro Schwann cell models were also established and subjected to gene transfection to inhibit and overexpress BIRC3.The data indicated that BIRC3 expression was significantly up-regulated after sciatic nerve injury.Both BIRC3 upregulation and downregulation affected the migration,proliferation and apoptosis of Schwan cells and affected the expression of related factors through activating c-fos and ERK signal pathway.Inhibition of BIRC3 delayed early Wallerian degeneration through inhibiting the apoptosis of Schwann cells after sciatic nerve injury.These findings suggest that BIRC3 plays an important role in peripheral nerve injury repair and regeneration.The study was approved by the Institutional Animal Care and Use Committee of Nantong University,China(approval No.2019-nsfc004)on March 1,2019.

Neutrophil peptide 1 accelerates the clearance of degenerative axons during Wallerian degeneration by activating macrophages after peripheral nerve crush injury

Macrophages play an important role in peripheral nerve regeneration,but the specific mechanism of regeneration is still unclear.Our preliminary findings indicated that neutrophil peptide 1 is an innate immune peptide closely involved in peripheral nerve regeneration.However,the mechanism by which neutrophil peptide 1 enhances nerve regeneration remains unclear.This study was designed to investigate the relationship between neutrophil peptide 1 and macrophages in vivo and in vitro in peripheral nerve crush injury.The functions of RAW 264.7 cells we re elucidated by Cell Counting Kit-8 assay,flow cytometry,migration assays,phagocytosis assays,immunohistochemistry and enzyme-linked immunosorbent assay.Axonal debris phagocytosis was observed using the CUBIC(Clear,Unobstructed Brain/Body Imaging Cocktails and Computational analysis)optical clearing technique during Wallerian degeneration.Macrophage inflammatory factor expression in different polarization states was detected using a protein chip.The results showed that neutrophil peptide 1 promoted the prolife ration,migration and phagocytosis of macrophages,and CD206 expression on the surfa ce of macrophages,indicating M2 polarization.The axonal debris clearance rate during Wallerian degeneration was enhanced after neutrophil peptide 1 intervention.Neutrophil peptide 1 also downregulated inflammatory factors interleukin-1α,-6,-12,and tumor necrosis factor-αin invo and in vitro.Thus,the results suggest that neutrophil peptide 1 activates macrophages and accelerates Wallerian degeneration,which may be one mechanism by which neutrophil peptide 1 enhances peripheral nerve regeneration.

Expression changes and bioinformatic analysis of Wallerian degeneration after sciatic nerve injury in rat

Wallerian degeneration （WD） remains an important research topic. Many genes are differentially expressed during the process of WD, but the precise mechanisms responsible for these differentiations are not completely understood. In this study, we used microarrays to analyze the expression changes of the distal nerve stump at 0, 1, 4, 7, 14, 21 and 28 days after sciatic nerve injury in rats. The data revealed 6 076 differentiatly-expressed genes, with 23 types of expression, specifically enriched in genes associated with nerve development and axonogenesis, cytokine biosynthesis, cell differentiation, cytokine/chemokine production, neuron differentiation, cytokinesis, phosphorylation and axon regeneration. Kyoto Encyclopedia of Genes and Genomes pathway analysis gave findings related mainly to the MAPK signaling pathway, the Jak-STAT signaling pathway, the cell cycle, cytokine-cytokine receptor interaction, the p53 signaling pathway and the Wnt signaling pathway. Some key factors were NGF, MAG, CNTF, CTNNA2, p53, JAK2, PLCB1, STAT3, BDNF, PRKC, collagen II, FGF, THBS4, TNC and c-Src, which were further validated by real-time quantitative PCR, Western blot, and immunohistochemistry. Our findings contribute to a better understanding of the functional analysis of differentially-expressed genes in WD and may shed light on the molecular mechanisms of nerve degeneration and regeneration.

Claudin 14/15 play important roles in early wallerian degeneration after rat sciatic nerve injury

Purpose:Wallerian degeneration(WD)is an antegrade degenerative process distal to peripheral nerve injury.Numerous genes are differentially regulated in response to the process.However,the underlying mechanism is unclear,especially the early response.We aimed at investigating the effects of sciatic nerve injury on WD via CLDN 14/15 interactionsin vivo andin vitro.Methods:Using the methods of molecular biology and bioinformatics analysis,we investigated the molecular mechanism by which claudin 14/15 participate in WD.Our previous study showed that claudins 14 and 15 trigger the early signal flow and pathway in damaged sciatic nerves.Here,we report the effects of the interaction between claudin 14 and claudin 15 on nerve degeneration and regeneration during early WD.Results:It was found that claudin 14/15 were upregulated in the sciatic nerve in WD.Claudin 14/15 promoted Schwann cell proliferation,migration and anti-apoptosisin vitro.PKCα,NT3,NF2,and bFGF were significantly upregulated in transfected Schwann cells.Moreover,the expression levels of theβ-catenin,p-AKT/AKT,p-c-jun/c-jun,and p-ERK/ERK signaling pathways were also significantly altered.Conclusion:Claudin 14/15 affect Schwann cell proliferation,migration,and anti-apoptosis via theβ-catenin,p-AKT/AKT,p-c-jun/c-jun,and p-ERK/ERK pathwaysin vitro andin vivo.The results of this study may help elucidate the molecular mechanisms of the tight junction signaling pathway underlying peripheral nerve degeneration.

Changes in proteins related to early nerve repair in a rat model of sciatic nerve injury

Peripheral nerves have a limited capacity for self-repair and those that are severely damaged or have significant defects are challenging to repair. Investigating the pathophysiology of peripheral nerve repair is important for the clinical treatment of peripheral nerve repair and regeneration. In this study, rat models of right sciatic nerve injury were established by a clamping method. Protein chip assay was performed to quantify the levels of neurotrophic, inflammation-related, chemotaxis-related and cell generation-related factors in the sciatic nerve within 7 days after injury. The results revealed that the expression levels of neurotrophic factors(ciliary neurotrophic factor) and inflammationrelated factors(intercellular cell adhesion molecule-1, interferon γ, interleukin-1α, interleukin-2, interleukin-4, interleukin-6, monocyte chemoattractant protein-1, prolactin R, receptor of advanced glycation end products and tumor necrosis factor-α), chemotaxis-related factors(cytokine-induced neutrophil chemoattractant-1, L-selectin and platelet-derived growth factor-AA) and cell generation-related factors(granulocyte-macrophage colony-stimulating factor) followed different trajectories. These findings will help clarify the pathophysiology of sciatic nerve injury repair and develop clinical treatments of peripheral nerve injury. This study was approved by the Ethics Committee of Peking University People's Hospital of China(approval No. 2015-50) on December 9, 2015.

Long noncoding RNA H19 regulates degeneration and regeneration of injured peripheral nerves

Our previous studies have shown that long noncoding RNA(lncRNA)H19 is upregulated in injured rat sciatic nerve during the process of Wallerian degeneration,and that it promotes the migration of Schwann cells and slows down the growth of dorsal root ganglion axons.However,the mechanism by which lncRNA H19 regulates neural repair and regeneration after peripheral nerve injury remains unclear.In this study,we established a Sprague-Dawley rat model of sciatic nerve transection injury.We performed in situ hybridization and found that at 4–7 days after sciatic nerve injury,lncRNA H19 was highly expressed.At 14 days before injury,adeno-associated virus was intrathecally injected into the L4–L5 foramina to disrupt or overexpress lncRNA H19.After overexpression of lncRNA H19,the growth of newly formed axons from the sciatic nerve was inhibited,whereas myelination was enhanced.Then,we performed gait analysis and thermal pain analysis to evaluate rat behavior.We found that lncRNA H19 overexpression delayed the recovery of rat behavior function,whereas interfering with lncRNA H19 expression improved functional recovery.Finally,we examined the expression of lncRNA H19 downstream target SEMA6D,and found that after lncRNA H19 overexpression,the SEMA6D protein level was increased.These findings suggest that lncRNA H19 regulates peripheral nerve degeneration and regeneration through activating SEMA6D in injured nerves.This provides a new clue to understand the role of lncRNA H19 in peripheral nerve degeneration and regeneration.

Polyethylene glycol has immunoprotective effects on sciatic allografts, but behavioral recovery and graft tolerance require neurorrhaphy and axonal fusion

Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.

Autophagy-targeting modulation to promote peripheral nerve regeneration

Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration.However,recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration,particularly in the context of traumatic injuries.Consequently,autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration.Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths,thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation.These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration.A range of autophagyinducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries.This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration,summarizing the potential drugs and interventions that can be harnessed to promote this process.We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.

大鼠坐骨神经Wallerian溃变的分子机制研究

目的:运用基因芯片和蛋白芯片技术及生物信息学分析,系统分析大鼠坐骨神经损伤后远端神经组织Wallerian溃变的差异表达基因和蛋白,从基因和蛋白水平探讨Wallerian溃变的分子机制。方法:建立大鼠损伤坐骨神经远端Wallerian溃变模型,利用表达谱基因芯片和抗体蛋白芯片,进行表达趋势分析、功能分析、京都基因与基因组百科全书信号通路分析。通过生物信息学方法全面系统分析,大鼠坐骨神经损伤后远端Wallerian溃变的基因和蛋白表达变化。结果:在Wallerian溃变和再生过程中,共有6076个基因差异表达和23种表达趋势,有93个蛋白差异表达,108种信号通路参与形成Wallerian溃变的信号调控网络。结论:大鼠坐骨神经损伤后Wallerian溃变过程中,有大量基因的表达变化和多种关键因子的调控,本研究为进一步阐明Wallerian溃变的分子机制提供了基本数据,为经典的Wallerian溃变学说增添了新的内容。

大鼠坐骨神经损伤后Wallerian溃变早期的基因表达变化

目的:探讨Wallerian溃变早期激活神经损伤修复与再生的分子机制。方法:建立大鼠损伤坐骨神经模型,通过表达谱基因芯片和生物信息学方法,全面系统分析大鼠坐骨神经损伤后远端Wallerian溃变早期的基因表达变化,运用RT-PCR、Western Blot和Immunohistochemistry等方法验证和鉴定表达谱基因芯片分析结果。结果:大鼠坐骨神经损伤后,坐骨神经远端在Wallerian溃变早期即有1546个显著表达差异基因和21种显著性差异基因表达趋势;基因功能注释和信号通路分析显示,Wallerian溃变早期有58种信号通路被激活,形成Wallerian溃变早期的信号调控网络。结论:大鼠坐骨神经损伤后Wallerian溃变早期即有大量基因的表达变化和多种信号途径的激活,本研究可为神经损伤修复与再生提供理论基础。

大鼠坐骨神经Wallerian溃变过程中LncRNA的差异表达分析

目的:采用分子生物学和生物信息学方法筛选大鼠坐骨神经损伤后Wallerian溃变(Wallerian degeneration,WD)过程中的关键长链非编码RNA(long none coding RNA, LncRNA),并分析该关键LncRNA分子在大鼠坐骨神经损伤过程中的作用。方法:采用Affymetrix大鼠Non Coding RNA芯片,分析大鼠坐骨神经损伤后WD过程中差异表达的LncRNA;通过实时定量聚合酶链式反应验证关键LncRNA的表达;预测关键LncRNA相关基因及功能。结果:基因芯片分析结果显示共有显著差异性LncRNA 708个和mRNA 2 649个,上调LncRNA 283个,下调LncRNA 425个。通过编码—非编码基因共表达分析和预测竞争性内源RNA(competitive endogenous RNA, ceRNA)机制,显示在WD过程中发挥作用的LncRNA,其中上调19个,下调17个。WD早期差异表达的LncRNA靶基因11个,WD后期差异表达的LncRNA靶基因31个。结论:大鼠坐骨神经损伤后,LncRNA显著差异性表达,提示LncRNA在周围神经损伤修复与再生过程中可能发挥了一定作用,为进一步分析LncRNA在神经再生中的作用提供了实验基础。

黄芪多糖对坐骨神经华勒变性大鼠细胞免疫功能的作用研究

目的:观察黄芪多糖对坐骨神经华勒(Wallerian)变性大鼠细胞免疫功能的影响。方法:Wistar大鼠10只,制作小间隙桥接双侧坐骨神经损伤模型。实验组给予腹腔注射黄芪多糖20mg/kg,对照组给予同体积生理盐水。连续给药7天。ELISA夹心法测定各组大鼠血清、脾细胞和巨噬细胞培养上清中IL-1β的含量。结果:实验组脾T淋巴细胞增殖能力巨噬细胞增殖能力明显强于对照组(P<0.05)。实验组脾细胞、巨噬细胞上清IL-1β水平高于对照组(P<0.05),两组动物血清中IL-1β水平没有显著差异(P>0.05)。结论:黄芪多糖对坐骨神经华勒变性大鼠细胞免疫功能有调节作用,并可能通过此方式影响神经再生。

神经节苷脂对大鼠坐骨神经损伤后神经纤维变化的作用研究

连续8d每天给大鼠ip10，20和50mg／kg神经节苷脂，d9将大鼠坐骨神经损伤，损伤后d7用图象分析仪检查该神经内有髓神经纤维变性情况。其中50mg／kg组有髓神经纤维华勒氏变性程度与对照组（ip生理盐水）相比大幅度减小；10mg／kg组无效；20mg／kg组有轻度减轻作用。以上各组中的有髓神经纤维轴突直径和神经纤维直径以及G值与正常有髓神经纤维相似，P＞0．05。正常大鼠坐骨神经损伤后d15观察发现其内的再生有髓神经纤维数约为正常坐骨神经的三分之一，其中的轴突直径和神经纤维直径均较大，约为正常有髓神经纤维的二倍，G值则较小，P＜0．05。结果提示，大鼠神经损伤前预防性给予的神经节苷脂能储存于机体内，在神经损伤后，它们迅速释放并参与神经的营养与生长修复工作，主要起到防止神经纤维华勒氏变性的作用，而不是促进变性的神经纤维再生。同时也说明，神经损伤之前机体内储存足量神经节苷脂对于预防神经华勒氏变性是重要的。

神经节苷脂对大鼠坐骨神经变性的影响及其机制的研究

目的：观察预防性给与神经节苷脂对大鼠坐骨神经切断后华勒氏变性的影响，并对其机制进行研究。方法：连续８ｄ给大鼠ｉｐ５０和８０ｍｇ·ｋｇ－１·ｄ－１神经节苷脂，第９天将大鼠坐骨神经切断，切断后分别于第７天，第１１天和第１６天用图象分析仪检查该神经远段内有髓神经纤维变性情况。结果：无论于第７天还是于第１１天观察，坐骨神经内均出现完整髓鞘神经纤维，而生理盐水对照组神经纤维全部崩解。前者各自的第７天组坐骨神经内神经纤维数均比第１１天组多，有显著性差异（Ｐ＜０．００１）；８０ｍｇ·ｋｇ－１组坐骨神经内神经纤维数与５０ｍｇ·ｋｇ－１组相比，无论于第７天还是于第１１天均无显著性差异（Ｐ＞０．０５）。以上各组神经纤维轴突直径，神经纤维直径以及它们之间的比值均与正常坐骨神经内有髓神经纤维相似（Ｐ＞０．０５）。无论是５０ｍｇ·ｋｇ－１组还是８０ｍｇ·ｋｇ－１组，于第１６天坐骨神经内均无完整髓鞘神经纤维。坐骨神经切断前后均用５０ｍｇ·ｋｇ－１，各组于切断后第７天、第１１天和第１６天坐骨神经内均保留有完整髓鞘神经纤维，其中第７天组与只在损伤前给５０ｍｇ·ｋｇ－１和８０ｍｇ·ｋｇ－１第７天两组相比无显著性差异（Ｐ＞０．０５）；而第１１?

神经节苷脂预防华勒变性的显微结构研究

目的：观察预防性给予神经节苷脂对神经切断后神经纤维变性的预防作用。方法：连续８ｄ给大鼠ｉｐ２０和５０ｍｇ·ｋｇ－１·ｄ－１神经节苷脂，ｄ９将大鼠坐骨神经切断，切断后分别于ｄ７和ｄ１１用图像分析仪检查该神经远段内有髓神经纤维变性情况。结果：５０ｍｇ·ｋｇ－１组坐骨神经内完整髓鞘的有髓神经纤维数目于ｄ７和ｄ１１分别比２０ｍｇ·ｋｇ－１组多。而且５０ｍｇ·ｋｇ－１和２０ｍｇ·ｋｇ－１２组完整髓鞘的有髓神经纤维数目于ｄ７均比于ｄ１１多。而两个生理盐水对照组（ｄ７和ｄ１１）内神经纤维普遍崩解，以上各组中的有髓神经纤维轴突直径和神经纤维直径以及它们之间的比值与正常有髓神经纤维相似（Ｐ＞０．０５）。而正常大鼠坐骨神经挫伤后ｄ１５观察发现其内的再生有髓神经纤维的轴突直径和神经纤维直径均较大，约为正常有髓神经纤维的２倍，比值则较小（Ｐ＜０．０５）。结论：大鼠神经损伤前预防性给予的神经节苷脂能防止神经纤维华勒氏变性，而不是促进变性的神经纤维再生。同时也说明，神经损伤之前机体内储存足量神经节苷脂在程度和时间上对于预防神经华勒氏变性是有益的。

周围神经Waller变性时的信息传递方式

为了检测 Waller变性时损伤部远侧段的溃变过程是同时发生还是自切断处逐渐向远侧离心式传递 ,本实验切断大鼠坐骨神经 ,将整个远侧段分为连续的 A、B、C三段 ,A段为最靠近切断处的部位。用 c-fos免疫组化方法和 EA50 组化方法 ,比较了三段之间的形态变化和阳性细胞数。结果显示 ,神经切断后 2 d,A、B、C三段间 c-fos阳性细胞数量有显著差异。至第 5天 ,这种差别消失 ,各段间阳性细胞数量表达无显著差异。实验结果说明 ,周围神经切断后 ,信息传递是由近至远地发生 ,也说明 Waller变性是由近至远地发生。至于神经切断后 ,引起

坐骨神经横断伤后远侧段组织的形态学及相关因子表达变化

目的:通过制备GFP小鼠和B6小鼠坐骨神经横断伤模型,应用免疫组化技术以及RealTime-PCR技术观察和分析周围神经损伤后远侧段组织的形态学及相关因子表达变化。方法:制备GFP小鼠坐骨神经横断伤模型,应用免疫组化技术分别染色S100蛋白以显示施万细胞,染色NF蛋白以显示轴突;结合GFP小鼠的自发荧光以及Hoechst核染观察横断伤后不同时间点远侧段组织的形态学变化。制备B6小鼠坐骨神经横断伤模型,应用RealTime-PCR技术检测横断伤后远侧段组织中相关营养因子BDNF、NGF、CNTF及抗凋亡因子Bcl-2 mRNA的表达变化。结果:坐骨神经横断伤后,远侧段施万细胞S100蛋白的表达第7天时达到高峰,第14天时下降,形成狭长细胞索带;第21～28天时仅少数细胞S100蛋白阳性。远侧段NF免疫组化产物于横断伤后第7天时断裂呈碎片状,第28天时碎片亦基本消失不见。远侧段非特异核染数目随损伤时间延长而增加。同时,在远侧段整个溃变过程中,神经基膜管结构仍然可见。坐骨神经横断伤后,BDNF mRNA表达第1～3周内逐渐上调,其中第3周时达到高峰(P<0.01),第4周时下降到与正常值相比无统计学意义的水平。NGF mRNA表达第1周时达到高峰(P<0.01),第2周时比第1周有小幅下降,但仍然具有统计学意义(P<0.01),第二周以后下降到与正常值相似的水平。CNTF mRNA表达则在损伤后第1周时下降了35%,第2周时继续下降到正常水平的42.7%,其下降均具有统计学意义(P<0.01),第3周时有所回升,第4周时下降到低点。Bcl-2 mRNA表达在损伤后第1周时下降,第2、3周时上升,第3周时达到高峰,并且上升具有统计学意义(P<0.01)。结论:坐骨神经横断伤后4周,远侧段神经组织中神经基膜管结构仍然存在。神经营养因子BDNF、NGF、CNTF mRNA的表达时相不同,提示其表达调控机制不同。Bcl-2 mRNA表达变化与施万细胞凋亡相关。