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.

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.

Brain plasticity after peripheral nerve injury treatment with massage therapy based on resting-state functional magnetic resonance imaging

Massage therapy is an alternative treatment for chronic pain that is potentially related to brain plasticity.However,the underlying mechanism remains unclear.We established a peripheral nerve injury model in rats by unilateral sciatic nerve transection and direct anastomosis.The experimental rats were treated over the gastrocnemius muscle of the affected hindlimb with a customized massage instrument(0.45 N,120 times/min,10 minutes daily,for 4 successive weeks).Resting-state functional magnetic resonance imaging revealed that compared with control rats,the amplitude of low-frequency fluctuations in the sensorimotor cortex contralateral to the affected limb was significantly lower after sciatic nerve transection.However,amplitudes were significantly higher in the massage group than in a sham-massage group.These findings suggest that massage therapy facilitated adaptive change in the somatosensory cortex that led to the recovery of peripheral nerve injury and repair.This study was approved by the Animal Ethics Committee of Shanghai University of Traditional Chinese Medicine of China(approval No.201701001)on January 12,2017.

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.

MK-801 attenuates lesion expansion following acute brain injury in rats: a meta-analysis

OBJECTIVE: To evaluate the efficacy and safety of MK-801 and its effect on lesion volume in rat models of acute brain injury.DATA SOURCES: Key terms were "stroke","brain diseases","brain injuries","brain hemorrhage, traumatic","acute brain injury","dizocilpine maleate","dizocilpine","MK-801","MK801","rat","rats","rattus" and "murine". PubMed, Cochrane library, EMBASE, the China National Knowledge Infrastructure, WanFang database, the VIP Journal Integration Platform(VJIP) and SinoMed databases were searched from their inception dates to March 2018.DATA SELECTION: Studies were selected if they reported the effects of MK-801 in experimental acute brain injury. Two investigators independently conducted literature screening, data extraction, and methodological quality assessments.OUTCOME MEASURES: The primary outcomes included lesion volume and brain edema. The secondary outcomes included behavioral assessments with the Bederson neurological grading system and the water maze test 24 hours after brain injury.RESULTS: A total of 52 studies with 2530 samples were included in the systematic review. Seventeen of these studies had a high methodological quality. Overall, the lesion volume(34 studies, n = 966, MD =-58.31, 95% CI:-66.55 to-50.07;P < 0.00001) and degree of cerebral edema(5 studies, n = 75, MD =-1.21, 95% CI:-1.50 to-0.91;P < 0.00001) were significantly decreased in the MK-801 group compared with the control group. MK-801 improved spatial cognition assessed with the water maze test(2 studies, n = 60, MD =-10.88, 95% CI:-20.75 to-1.00;P = 0.03) and neurological function 24 hours after brain injury(11 studies, n = 335, MD =-1.04, 95% CI:-1.47 to-0.60;P < 0.00001). Subgroup analysis suggested an association of reduction in lesion volume with various injury models(34 studies, n = 966, MD =-58.31, 95% CI:-66.55 to-50.07;P = 0.004). Further network analysis showed that 0–1 mg/kg MK-801 may be the optimal dose for treatment in the middle cerebral artery occlusion animal model.CONCLUSION: MK-801 effectively reduces brain lesion volume and the degree of cerebral edema in rat models of experimental acute brain injury, providing a good neuroprotective effect. Additionally, MK-801 has a good safety profile, and its mechanism of action is well known. Thus, MK-801 may be suitable for future clinical trials and applications.

End-to-side neurorrhaphy repairs peripheral nerve injury：sensory nerve induces motor nerve regeneration

End-to-side neurorrhaphy is an option in the treatment of the long segment defects of a nerve.It involves suturing the distal stump of the disconnected nerve（recipient nerve） to the side of the intimate adjacent nerve（donor nerve）.However,the motor-sensory specificity after end-to-side neurorrhaphy remains unclear.This study sought to evaluate whether cutaneous sensory nerve regeneration induces motor nerves after end-to-side neurorrhaphy.Thirty rats were randomized into three groups：（1） end-to-side neurorrhaphy using the ulnar nerve（mixed sensory and motor） as the donor nerve and the cutaneous antebrachii medialis nerve as the recipient nerve;（2） the sham group：ulnar nerve and cutaneous antebrachii medialis nerve were just exposed;and（3） the transected nerve group：cutaneous antebrachii medialis nerve was transected and the stumps were turned over and tied.At 5 months,acetylcholinesterase staining results showed that 34% ± 16% of the myelinated axons were stained in the end-to-side group,and none of the myelinated axons were stained in either the sham or transected nerve groups.Retrograde fluorescent tracing of spinal motor neurons and dorsal root ganglion showed the proportion of motor neurons from the cutaneous antebrachii medialis nerve of the end-to-side group was 21% ± 5%.In contrast,no motor neurons from the cutaneous antebrachii medialis nerve of the sham group and transected nerve group were found in the spinal cord segment.These results confirmed that motor neuron regeneration occurred after cutaneous nerve end-to-side neurorrhaphy.

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.

Analysis of transcriptome sequencing of sciatic nerves in Sprague-Dawley rats of different ages

An aging-induced decrease in Schwann cell viability can affect regeneration following peripheral nerve injury in mammals. It is therefore necessary to investigate possible age-related changes in gene expression that may affect the biological function of peripheral nerves. Ten 1-week-old and ten 12-month-old healthy male Sprague-Dawley rats were divided into young（1 week old） and adult（12 months old） groups according to their ages. mRNA expression in the sciatic nerve was compared between young and adult rats using next-generation sequencing（NGS） and bioinformatics（n = 4/group）. The 18 groups of differentially expressed mRNA（DEmRNAs） were also tested by quantitative reverse transcription polymerase chain reaction（n = 6/group）. Results revealed that（1） compared with young rats, adult rats had 3608 groups of DEmRNAs. Of these, 2684 were groups of upregulated genes, and 924 were groups of downregulated genes. Their functions mainly involved cell viability, proliferation, differentiation, regeneration, and myelination.（2） The gene with the most obvious increase of all DEmRNAs in adult rats was Thrsp（log2 FC = 9.01, P 〈 0.05）, and the gene with the most obvious reduction was Col2 a1（log2 FC = -8.89, P 〈 0.05）.（3） Gene Ontology analysis showed that DEmRNAs were mainly concentrated in oligosaccharide binding, nucleotide-binding oligomerization domain containing one signaling pathway, and peptide-transporting ATPase activity.（4） Analysis using the Kyoto Encyclopedia of Genes and Genomes showed that, with increased age, DEmRNAs were mainly enriched in steroid biosynthesis, Staphylococcus aureus infection, and graft-versus-host disease.（5） Spearman＇s correlation coefficient method for evaluating NGS accuracy showed that the NGS results and quantitative reverse transcription polymerase chain reaction results were positively correlated（rs = 0.74, P 〈 0.05）. These findings confirm a difference in sciatic nerve gene expression between adult and young rats, suggesting that, in peripheral nerves, cells and the microenvironment change with age, thus influencing the function and repair of peripheral nerves.

The longitudinal epineural incision and complete nerve transection method for modeling sciatic nerve injury

Injury severity, operative technique and nerve regeneration are important factors to consider when constructing a model of peripheral nerve injury. Here, we present a novel peripheral nerve injury model and compare it with the complete sciatic nerve transection method. In the experimental group, under a microscope, a 3-mm longitudinal incision was made in the epineurium of the sciatic nerve to reveal the nerve fibers, which were then transected. The small, longitudinal incision in the epineurium was then sutured closed, requiring no stump anastomosis. In the control group, the sciatic nerve was completely transected, and the epineurium was repaired by anastomosis. At 2 and 4 weeks after surgery, Wallerian degeneration was observed in both groups. In the experimental group, at 8 and 12 weeks after surgery, distinct medullary nerve fibers and axons were observed in the injured sciatic nerve. Regular, dense myelin sheaths were visible, as well as some scarring. By 12 weeks, the myelin sheaths were normal and intact, and a tight lamellar structure was observed. Functionally, limb movement and nerve conduction recovered in the injured region between 4 and 12 weeks. The present results demonstrate that longitudinal epineural incision with nerve transection can stably replicate a model of Sunderland grade IV peripheral nerve injury. Compared with the complete sciatic nerve transection model, our method reduced the difficulties of micromanipulation and surgery time, and resulted in good stump restoration, nerve regeneration, and functional recovery.

Penile erectile dysfunction after brachial plexus root avulsion injury in rats

Our previous studies have demonstrated that some male patients suffering from brachial plexus injury, particularly brachial plexus root avulsion, show erectile dysfunction to varying degrees. However, the underlying mechanism remains poorly understood. In this study, we evaluated the erectile function after establishing brachial plexus root avulsion models with or without spinal cord injury in rats. After these models were established, we administered apomorphine （via a sub- cutaneous injection in the neck） to observe changes in erectile function. Rats subjected to simple brachial plexus root avulsion or those subjected to brachial plexus root avulsion combined with spinal cord injury had significantly fewer erections than those subjected to the sham operation. Expression of neuronal nitric oxide synthase did not change in brachial plexus root avulsion rats. However, neuronal nitric oxide synthase expression was significantly decreased in brachial plexus root avulsion ＋ spinal cord injury rats. These findings suggest that a decrease in neuronal nitric oxide synthase expression in the penis may play a role in erectile dysfunction caused by the combi- nation of brachial plexus root avulsion and spinal cord injury.

Characteristics of cytokines in the sciatic nerve stumps and DRG after rat sciatic nerve crush injury

Background: Cytokines are essential cellular modulators of various physiological and pathological activities, including peripheral nerve repair and regeneration. However, the molecular changes of these cellular mediators after peripheral nerve injury are still unclear. This study aimed to identify cytokines critical for the regenerative process of injured peripheral nerves.Methods: The sequencing data of the injured nerve stumps and the dorsal root ganglia(DRG) of Sprague-Dawley(SD) rats subjected to sciatic nerve(SN) crush injury were analyzed to determine the expression patterns of genes coding for cytokines. PCR was used to validate the accuracy of the sequencing data.Results: A total of 46, 52, and 54 upstream cytokines were differentially expressed in the SN at 1 day, 4 days, and 7 days after nerve injury. A total of 25, 28, and 34 upstream cytokines were differentially expressed in the DRG at these time points. The expression patterns of some essential upstream cytokines are displayed in a heatmap and were validated by PCR. Bioinformatic analysis of these differentially expressed upstream cytokines after nerve injury demonstrated that inflammatory and immune responses were significantly involved.Conclusions: In summary, these findings provide an overview of the dynamic changes in cytokines in the SN and DRG at different time points after nerve crush injury in rats, elucidate the biological processes of differentially expressed cytokines, especially the important roles in inflammatory and immune responses after peripheral nerve injury, and thus might contribute to the identification of potential treatments for peripheral nerve repair and regeneration.

Acetyl-11-keto-beta-boswellic acid promotes sciatic nerve repair after injury: molecular mechanism

Previous studies showed that acetyl-11-keto-beta-boswellic acid(AKBA),the active ingredient in the natural Chinese medicine Boswellia,can stimulate sciatic nerve injury repair via promoting Schwann cell proliferation.However,the underlying molecular mechanism remains poorly understood.In this study,we performed genomic sequencing in a rat model of sciatic nerve crush injury after gastric AKBA administration for 30 days.We found that the phagosome pathway was related to AKBA treatment,and brain-derived neurotrophic factor expression in the neurotrophic factor signaling pathway was also highly up-regulated.We further investigated gene and protein expression changes in the phagosome pathway and neurotrophic factor signaling pathway.Myeloperoxidase expression in the phagosome pathway was markedly decreased,and brain-derived neurotrophic factor,nerve growth factor,and nerve growth factor receptor expression levels in the neurotrophic factor signaling pathway were greatly increased.Additionally,expression levels of the inflammatory factors CD68,interleukin-1β,pro-interleukin-1β,and tumor necrosis factor-αwere also decreased.Myelin basic protein-andβ3-tubulin-positive expression as well as the axon diameter-to-total nerve diameter ratio in the injured sciatic nerve were also increased.These findings suggest that,at the molecular level,AKBA can increase neurotrophic factor expression through inhibiting myeloperoxidase expression and reducing inflammatory reactions,which could promote myelin sheath and axon regeneration in the injured sciatic nerve.

Epalrestat protects against diabetic peripheral neuropathy by alleviating oxidative stress and inhibiting polyol pathway

Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.

Decellularized sciatic nerve matrix as a biodegradable conduit for peripheral nerve regeneration

The use of autologous nerve grafts remains the gold standard for treating nerve defects, but current nerve repair techniques are limited by donor tissue availability and morbidity associated with tissue loss. Recently, the use of conduits in nerve injury repair, made possible by tissue engineering, has shown therapeutic potential. We manufactured a biodegradable, collagen-based nerve conduit containing decellularized sciatic nerve matrix and compared this with a silicone conduit for peripheral nerve regeneration using a rat model. The collagen-based conduit contains nerve growth factor, brain-derived neurotrophic factor, and laminin, as demonstrated by enzyme-linked immunosorbent assay. Scanning electron microscopy images showed that the collagen-based conduit had an outer wall to prevent scar tissue infiltration and a porous inner structure to allow axonal growth. Rats that were implanted with the collagen-based conduit to bridge a sciatic nerve defect experienced significantly improved motor and sensory nerve functions and greatly enhanced nerve regeneration compared with rats in the sham control group and the silicone conduit group. Our results suggest that the biodegradable collagen-based nerve conduit is more effective for peripheral nerve regeneration than the silicone conduit.

A novel tissue engineered nerve graft constructed with autologous vein and nerve microtissue repairs a longsegment sciatic nerve defect

Veins are easy to obtain,have low immunogenicity,and induce a relatively weak inflammatory response.Therefore,veins have the potential to be used as conduits for nerve regeneration.However,because of the presence of venous valves and the great elasticity of the venous wall,the vein is not conducive to nerve regeneration.In this study,a novel tissue engineered nerve graft was constructed by combining normal dissected nerve microtissue with an autologous vein graft for repairing 10-mm peripheral nerve defects in rats.Compared with rats given the vein graft alone,rats given the tissue engineered nerve graft had an improved sciatic static index,and a higher amplitude and shorter latency of compound muscle action potentials.Furthermore,rats implanted with the microtissue graft had a higher density and thickness of myelinated nerve fibers and reduced gastrocnemius muscle atrophy compared with rats implanted with the vein alone.However,the tissue engineered nerve graft had a lower ability to repair the defect than autogenous nerve transplantation.In summary,although the tissue engineered nerve graft constructed with autologous vein and nerve microtissue is not as effective as autologous nerve transplantation for repairing long-segment sciatic nerve defects,it may nonetheless have therapeutic potential for the clinical repair of long sciatic nerve defects.This study was approved by the Experimental Animal Ethics Committee of Chinese PLA General Hospital(approval No.2016-x9-07)on September 7,2016.

Experimental nerve transfer model in the neonatal rat

Clinically,peripheral nerve reconstructions in neonates are most frequently applied in brachial plexus birth injuries.Most surgical concepts,however,have investigated nerve reconstructions in adult animal models.The immature neuromuscular system reacts differently to the effects of nerve lesion and surgery and is poorly investigated due to the lack of reliable experimental models.Here,we describe an experimental forelimb model in the neonatal rat,to study these effects on both the peripheral and central nervous systems.Within 24 hours after birth,three groups were prepared:In the nerve transfer group,a lesion of the musculocutaneous nerve was reconstructed by selectively transferring the ulnar nerve.In the negative control group,the musculocutaneous nerve was divided and not reconstructed and in the positive control group,a sham surgery was performed.The animal's ability to adapt to nerve lesions and progressive improvement over time were depict by the Bertelli test,which observes the development of grooming.Twelve weeks postoperatively,animals were fully matured and the nerve transfer successfully reinnervated their target muscles,which was indicated by muscle force,muscle weight,and cross sectional area evaluation.On the contrary,no spontaneous regeneration was found in the negative control group.In the positive control group,reference values were established.Retrograde labeling indicated that the motoneuron pool of the ulnar nerve was reduced following nerve transfer.Due to this post-axotomy motoneuron death,a diminished amount of motoneurons reinnervated the biceps muscle in the nerve transfer group,when compared to the native motoneuron pool of the musculocutaneous nerve.These findings indicate that the immature neuromuscular system behaves profoundly different than similar lesions in adult rats and explains reduced muscle force.Ultimately,pathophysiologic adaptations are inevitable.The maturing neuromuscular system,however,utilizes neonatal capacity of regeneration and seizes a variety of compensation mechanism to restore a functional extremity.The above described neonatal rat model demonstrates a constant anatomy,suitable for nerve transfers and allows all standard neuromuscular analyses.Hence,detailed investigations on the pathophysiological changes and subsequent effects of trauma on the various levels within the neuromuscular system as well as neural reorganization of the neonatal rat may be elucidated.This study was approved by the Ethics Committee of the Medical University of Vienna and the Austrian Ministry for Research and Science(BMWF-66.009/0187-WF/V/3 b/2015)on March 20,2015.

电针与干细胞治疗大鼠急性周围神经损伤的磁共振扩散张量成像评估

目的运用磁共振扩散张量成像技术(diffusion tensor imaging,DTI)评估电针与干细胞移植在急性周围神经损伤疾病中的治疗效果。材料与方法将48只造模成功的成年SD大鼠随机平均分为电针组、干细胞组和对照组,每组16只。电针组大鼠接受环跳和足三里的电针治疗。干细胞组大鼠于损伤处神经外膜下微量注射3μL含有约5×105个骨髓间充质干细胞的生理盐水悬浊液。对照组显微注射同体积的生理盐水。使用多参数磁共振成像技术包括DTI和磁共振T2加权脂肪饱和序列(T2-weighted fat saturation,T2WI-FS)、组织学评估、免疫组化分析监测神经结构的变化(包括神经直径、髓鞘厚度及形态改变、轴突连续性的恢复)。运用坐骨神经功能指数(somatic functional index,SFI)和步行轨迹分析方法评估神经的运动功能。采用重复测量单因素方差分析不同实验组间大鼠磁共振横向弛豫时间(T2值)、DTI指标[各向异性分数(fractional anisotropy,FA)和径向扩散率(radial diffusivity,RD)]、SFI值的差异性。运用Bonferroni检验校正不同时间节点下多重检验的阈值结果。结果急性周围神经损伤后第1周,所有组大鼠的FA值显著下降,随后逐渐升高,直至第4周恢复至接近正常水平;而RD值在手术后1周内显著上升,随后逐渐下降,同样于第4周时恢复至接近正常水平。电针组和干细胞组大鼠在术后不同时间点(2~4周)的恢复均优于对照组,且电针组的恢复最为显著(P<0.001)。T2WI-FS显示在术后的1、2、4周,电针组及干细胞组大鼠与对照组大鼠相比在神经水肿消退速度方面具有显著差异(P<0.001);神经直径与T2值在手术后1周内显著升高,此后逐渐下降,在第4周时恢复至接近正常水平;甲苯胺蓝染色与SPRR1A轴突染色均指向电针组的神经纤维连续性恢复最快,其次是干细胞组。结论电针在急性周围神经损伤疾病中的治疗效果可与干细胞移植治疗相当,并在减轻水肿及炎性反应方面极具优势。DTI参数FA和RD值是髓鞘完整性的成像标志物。

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.

桃红四物汤改善紫杉醇导致的大鼠外周神经损伤的机制研究

目的探索桃红四物汤(THD)改善紫杉醇(PTX)导致的大鼠外周神经损伤的作用机制。方法考察THD(1 g/mL含药血清)、PTX(0.1μmol/L)单用和联用下对施万细胞系RSC96细胞增殖率以及自噬溶酶体关联膜蛋白2(LAMP2)、自噬标记蛋白酵母Atg6同源物(Beclin1)、磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)、哺乳动物雷帕霉素靶蛋白(mTOR)表达的影响,并与自噬促进剂雷帕霉素和自噬抑制剂3-甲基腺嘌呤(3-MA)进行比较。考察THD高、低剂量对PTX导致的外周神经损伤模型大鼠坐骨神经中髓鞘碱性蛋白质(MBP)、鞘磷脂蛋白(MPZ)、S100钙结合蛋白(S100)、LAMP2、Beclin1、PI3K、Akt、mTOR表达的影响。结果THD+PTX作用下RSC96细胞增殖率显著高于PTX单用;THD+PTX、THD+3-MA作用下RSC96细胞中LAMP2、Beclin1蛋白的表达显著高于PTX、3-MA单用,PI3K、Akt、mTOR蛋白的表达显著低于PTX、3-MA单用(P<0.05)。与模型组相比,THD高、低剂量组大鼠坐骨神经中MBP、MPZ、S100、LAMP2、Beclin1蛋白表达均显著升高,PI3K、Akt、mTOR蛋白表达均显著降低(P<0.05)。结论THD可能通过抑制PI3K/Akt/mTOR信号通路来激活施万细胞自噬,从而改善PTX导致的外周神经损伤。

臭牡丹调控脊髓N-甲基-D-天冬氨酸受体亚基缓解神经病理性疼痛

目的:探讨臭牡丹(Clerodendrum bungei Steud.,CBS)的镇痛作用是否与N-甲基-D-天冬氨酸(N-methyl-Daspartate,NMDA)受体相关。方法:雄性成年SD大鼠24只,随机分为假手术组(Sham组)、坐骨神经分支选择性损伤(Spared nerve injury,SNI)模型组(SNI组)和30 g·kg^(-1)CBS治疗组(SNI+CBS组)。SNI+CBS组于SNI术后第7 d灌胃给予CBS,持续21 d,Sham组和SNI组给予同等体积的生理盐水灌胃。于术后第26~28 d检测大鼠步态;第28 d取脊髓,qPCR方法检测NMDA受体亚基GluNR1、GluN2A、GluN2B和GluN3A mRNA表达,Western blot和免疫荧光方法检测GluN2A和GluN2B蛋白水平,分子对接方法模拟CBS中主要成分与GluN2B的亲和力。结果:与Sham组相比,SNI模型组大鼠患肢的站立时间、最大接触时的最大强度、足印长度、足印宽度和爪印面积降低,最大接触时间百分比升高,脊髓GluN2A、GluN2B和GluN3A mRNA表达降低,GluN2A和GluN2B蛋白水平升高。与SNI组相比,SNI+CBS组大鼠患肢的站立时间、最大接触时的最大强度、足印长度和足印宽度升高,最大接触时间百分比降低,脊髓GluN2A、GluN2B和GluN3A mRNA表达升高,GluN2A和GluN2B蛋白水平降低。各组GluNR1 mRNA表达差异无统计学意义(P>0.05)。分子对接实验结果显示,原始配体Ro25-6981与GluN2B对接的结合自由能(△G)为−11.72 KJ·mol^(-1),估计抑制常数(Ki)为2.58 nmol;CBS主要成分α-香树脂醇、赪桐酮和木栓酮与GluN2B对接的△G及Ki与Ro25-6981接近,甚至优于Ro25-6981;从对接构象上看,Ro25-6981与木栓酮占据了GluN1B结合位点,α-香树脂醇和赪桐酮则占据了GluN2B结合位点,呈现出较强的NMDA受体抑制作用。结论:CBS对SNI模型所致神经病理性疼痛具有缓解作用,其机制可能是通过抑制NMDA受体来实现。