Bi-directional Control of Synaptic Input Summation and Spike Generation by GABAergic Inputs at the Axon Initial Segment / 神经科学通报·英文版

Differing from other subtypes of inhibitory interneuron, chandelier or axo-axonic cells form depolarizing GABAergic synapses exclusively onto the axon initial segment (AIS) of targeted pyramidal cells (PCs). However, the debate whether these AIS-GABAergic inputs produce excitation or inhibition in neuronal processing is not resolved. Using realistic NEURON modeling and electrophysiological recording of cortical layer-5 PCs, we quantitatively demonstrate that the onset-timing of AIS-GABAergic input, relative to dendritic excitatory glutamatergic inputs, determines its bi-directional regulation of the efficacy of synaptic integration and spike generation in a PC. More specifically, AIS-GABAergic inputs promote the boosting effect of voltage-activated Na+ channels on summed synaptic excitation when they precede glutamatergic inputs by >15 ms, while for nearly concurrent excitatory inputs, they primarily produce a shunting inhibition at the AIS. Thus, our findings offer an integrative mechanism by which AIS-targeting interneurons exert sophisticated regulation of the input-output function in targeted PCs.

Neuronal guidance genes in health and diseases

Neurons migrate from their birthplaces to the destinations, and extending axons navigate to their synaptic targets by sensing various extracellular cues in spatiotemporally controlled manners. These evolutionally conserved guidance cues and their receptors regulate multiple aspects of neural development to establish the highly complex nervous system by mediating both short- and long-range cell-cell communications. Neuronal guidance genes (encoding cues, receptors, or downstream signal transducers) are critical not only for development of the nervous system but also for synaptic maintenance, remodeling, and function in the adult brain. One emerging theme is the combinatorial and complementary functions of relatively limited classes of neuronal guidance genes in multiple processes, including neuronal migration, axonal guidance, synaptogenesis, and circuit formation. Importantly, neuronal guidance genes also regulate cell migration and cell-cell communications outside the nervous system. We are just beginning to understand how cells integrate multiple guidance and adhesion signaling inputs to determine overall cellular/subcellular behavior and how aberrant guidance signaling in various cell types contributes to diverse human diseases, ranging from developmental, neuropsychiatric, and neurodegenerative disorders to cancer metastasis. We review classic studies and recent advances in understanding signaling mechanisms of the guidance genes as well as their roles in human diseases. Furthermore, we discuss the remaining challenges and therapeutic potentials of modulating neuronal guidance pathways in neural repair.

Projection-Specific Heterogeneity of the Axon Initial Segment of Pyramidal Neurons in the Prelimbic Cortex / 神经科学通报·英文版

The axon initial segment (AIS) is a highly specialized axonal compartment where the action potential is initiated. The heterogeneity of AISs has been suggested to occur between interneurons and pyramidal neurons (PyNs), which likely contributes to their unique spiking properties. However, whether the various characteristics of AISs can be linked to specific PyN subtypes remains unknown. Here, we report that in the prelimbic cortex (PL) of the mouse, two types of PyNs with axon projections either to the contralateral PL or to the ipsilateral basal lateral amygdala, possess distinct AIS properties reflected by morphology, ion channel expression, action potential initiation, and axo-axonic synaptic inputs from chandelier cells. Furthermore, projection-specific AIS diversity is more prominent in the superficial layer than in the deep layer. Thus, our study reveals the cortical layer- and axon projection-specific heterogeneity of PyN AISs, which may endow the spiking of various PyN types with exquisite modulation.

Netrin-3 Suppresses Diabetic Neuropathic Pain by Gating the Intra-epidermal Sprouting of Sensory Axons / 神经科学通报·英文版

Diabetic neuropathic pain (DNP) is the most common disabling complication of diabetes. Emerging evidence has linked the pathogenesis of DNP to the aberrant sprouting of sensory axons into the epidermal area; however, the underlying molecular events remain poorly understood. Here we found that an axon guidance molecule, Netrin-3 (Ntn-3), was expressed in the sensory neurons of mouse dorsal root ganglia (DRGs), and downregulation of Ntn-3 expression was highly correlated with the severity of DNP in a diabetic mouse model. Genetic ablation of Ntn-3 increased the intra-epidermal sprouting of sensory axons and worsened the DNP in diabetic mice. In contrast, the elevation of Ntn-3 levels in DRGs significantly inhibited the intra-epidermal axon sprouting and alleviated DNP in diabetic mice. In conclusion, our studies identified Ntn-3 as an important regulator of DNP pathogenesis by gating the aberrant sprouting of sensory axons, indicating that Ntn-3 is a potential druggable target for DNP treatment.

Protective effects of Slit2 on corneal epithelium and nerves in diabetic mice and its mechanism / 中华实验眼科杂志

Objective:To explore the promoting effects of slit guidance ligand 2 (Slit2) on the repair of corneal epithelium and nerve damage in diabetic mice and possible molecular mechanism.Methods:Sixty SPF C57BL/6 mice aged 5-6 weeks were divided into normal control group, diabetes model group and Slit2 injection group according to the random number table method, 20 for each group.Diabectic model was prepared by intraperitoneal injection of streptozotocin in the diabetes model group and Slit2 injection group.A mouse corneal epithelial injury repair model was established using electric epithelial scraper, and Slit2 recombinant protein was subconjunctivally injected immediately following modeling in the Slit2 injection group.The equal volume of phosphate buffer saline (PBS) was used in a same way in the diabetes model group.No intervention was performed in the normal control group.Corneal epithelial healing were examined at 24, 48 and 72 hours after corneal epithelial defect by corneal fluorescin staining.Real-time fluorescent quantitative PCR was used to detect the expression of Slit2 and its related receptors in the corneal epithelium of normal and diabetic model mice.Fluorescence staining of corneal wholemount with β-tubulin Ⅲ was used to observe the changes in corneal nerve morphology.Immunofluorescence staining was performed to detect the expression and distribution of Slit2 in mouse corneal epithelium in normal control group and diabetes model group, as well as the expression and distribution of Slit2, epidermal growth factor receptor (EGFR), extracellular-signal-regulated kinase (ERK), threonine protein kinase (AKT), β-catenin and Ki67 in the healing corneal epithelium of mice after corneal epithelium damage in different groups.The mouse corneal epithelial stem/progenitor cell line (TKE2) was divided into normal control group, high-glucose group and Slit2 treatment group.Western blot was performed to detect the expression of p-EGFR/EGFR and p-AKT/AKT in the TKE2 of the three groups.The expression of p-EGFR/EGFR and p-AKT/AKT in high glucose-cultured TKE2 with 0.01, 0.1 and 0.5 μg/ml Slit2 treatment for 10 minutes, and before and 10, 20, 30, 60, 120 minutes after 0.5 μg/ml Slit2 treatment was detected by Western blot.The effects of Slit2 on the axon regeneration of mouse trigeminal ganglion cells (TGs) were observed by immunofluorescence staining.The use and care of animals complied with the ARVO statement.This study protocol was approved by an Ethics Committee of Qingdao Eye Hospital of Shandong First Medical University (No.[2020]57).Results:At 48 and 72 hours after corneal epithelial scraping, the speed of corneal epithelial repair was significantly slowed down in diabetes model group in comparison with the normal control group and Slit2 injection group.The relative expression levels of Slit2 and its receptors Robo1, Robo2 and Robo4 mRNA in the normal corneal epithelium in the diabetes model group were significantly higher than those of the normal control group (all at P<0.05). The fluorescence intensity of Slit2 in normal corneal epithelium in diabetes model group was similar to the normal control group, and the fluorescence intensity of Slit2 in damaged corneal epithelium in diabetic mice was significantly weaker than that in normal control group.Corneal nerve plexus was denser at 7 days after corneal epithelial injury and the nerve fibers were increased with more branches in Slit2 injection group compared with diabetic group.The fluorescence intensity of p-EGFR, p-ERK, β-catenin and Ki67 in damaged corneal epithelium in normal control group and Slit2 injection group was stronger than that of the diabetes model group.The relative expression levels of p-EGFR/EGFR, p-AKT/AKT, and β-catenin in TKE2 in high-glucose group were significantly lower than those in normal control group and Slit2 treatment group (all at P<0.05). The relative expression levels of p-EGFR/EGFR and p-AKT/AKT in high glucose-cultured TKE2 after Slit2 treatment were significantly increased in comparison with before Slit2 treatment (both at P<0.05), and the relative expression levels of p-EGFR/EGFR and p-AKT/AKT in TKE2 were elevated as the increase of Slit2 concentration.The activation effect of 0.5 μg/ml Slit2 on EGFR and AKT pathways was most obvious.The synapse length of TGs cultured by high glucose was (40.52±5.44) μm, which was significantly shortened than (72.14±9.48) μm in normal control group and (73.04±4.66) μm in Slit2 injection group (both at P<0.05). Conclusions:Slit2 can protect the corneal epithelium by activating EGFR signaling pathway and play a protective role to neurons by increasing the density of corneal subepithelial plexus and promoting the growth of TGs axons in diabetic mice.

Regulation of Axon Initial Segment Diameter by COUP-TFI Fine-tunes Action Potential Generation / 神经科学通报·英文版

The axon initial segment (AIS) is a specialized structure that controls neuronal excitability via action potential (AP) generation. Currently, AIS plasticity with regard to changes in length and location in response to neural activity has been extensively investigated, but how AIS diameter is regulated remains elusive. Here we report that COUP-TFI (chicken ovalbumin upstream promotor-transcription factor 1) is an essential regulator of AIS diameter in both developing and adult mouse neocortex. Either embryonic or adult ablation of COUP-TFI results in reduced AIS diameter and impaired AP generation. Although COUP-TFI ablations in sparse single neurons and in populations of neurons have similar impacts on AIS diameter and AP generation, they strengthen and weaken, respectively, the receiving spontaneous network in mutant neurons. In contrast, overexpression of COUP-TFI in sparse single neurons increases the AIS diameter and facilitates AP generation, but decreases the receiving spontaneous network. Our findings demonstrate that COUP-TFI is indispensable for both the expansion and maintenance of AIS diameter and that AIS diameter fine-tunes action potential generation and synaptic inputs in mammalian cortical neurons.

Ultrastructural clarification of the peripherally located actin network in the myelinated axons / Aclaración ultraestructural de la red de actina localizada periféricamente en los axones mielinizados

SUMMARY: Despite the existence of a large amount of actin in the axons, the concentration F-actin was quite low in the myelinated axons and almost all the F-actin were located in the peripheries of the myelinated axons. Until now, the ultrastructural localization of F-actin has still not been reported in the myelinated axons, probably due to the lack of an appropriate detection method. In the present study, a phalloidin-based FITC-anti-FITC technique was adopted to investigate the subcellular localization of F-actin in the myelinated axons. By using this technique, F-actin is located in the outer and inner collars of myelinated cytoplasm surrounding the intermodal axon, the Schmidt-Lanterman incisures, the paranodal terminal loops and the nodal microvilli. In addition, the satellite cell envelope, which encapsulates the axonal initial segment of the peripheral sensory neuron, was also demonstrated as an F-actin-enriched structure. This study provided a hitherto unreported ultrastructural view of the F-actin in the myelinated axons, which may assist in understanding the unique organization of axonal actin cytoskeleton.

RESUMEN: A pesar de la existencia de una gran cantidad de actina en los axones, la concentración de F-actina era bastante baja en los axones mielinizados y casi la totalidad de F-actina se localizaba en las periferias de los axones mielinizados. A la fecha aún no se ha reportado la localización ultraestructural de F-actina en los axones mielinizados, probablemente debido a la falta de un método de detección apropiado. En el presente estudio, se adoptó una técnica FITC-anti-FITC basada en faloidina para investigar la localización subcelular de F-actina en los axones mielinizados. Mediante el uso de esta técnica, la F-actina se localiza en los collares externo e interno del citoplasma mielinizado que rodea el axón intermodal, a las incisiones de Schmidt-Lanterman,a las asas terminales paranodales y a las microvellosidades nodales. Además, la envoltura de la célula satélite, que encapsula el segmento axonal inicial de la neurona sensorial periférica, también se demostró como una estructura enriquecida con F-actina. Este estudio proporcionó una vista ultraestructural de la F-actina en los axones mielinizados, que puede ayudar a comprender la organización única del citoesqueleto de actina axonal.

The effect of rehabilitation training on the expression of neuroglobin in the peri-infarct cortex and its mechanism / 中华物理医学与康复杂志

Objective:To study the effect of rehabilitation training on the expression of neuroglobin (Ngb), oxidative stress and axon regeneration in the cortex and explore possible mechanisms of functional recovery after cerebral infarction.Methods:Thirty-six male Sprague-Dawley rats were randomly divided into a sham operation group, a model group and a rehabilitation group. Cerebral infarction was modelled in the model and rehabilitation groups using Longa′s middle cerebral artery occlusion (MCAO) technique. The sham operation group received the same procedure except that no thread was inserted to block the middle cerebral artery. The rats in the rehabilitation group began treadmill training 24h after the operation, while the other two groups were left on the treadmill without training. On the 3rd, 7th and 14th days after the operation, all of the rats′ neurological functioning was assessed using modified neurological severity scores (mNSSs). After the last mNSS test, all of the rats were sacrificed and peri-infarct brain tissue was resected to detect the expression of Ngb and oxidative stress indicators including superoxide dismutase (SOD), nitric oxide and malondialdehyde (MDA), as well as neurofilament-200 (NF-200) indicating axon regeneration.Results:On the 3rd day after the surgery there was no significant difference between the average mNSS scores of the rehabilitation and model groups. On the 7th and 14th day the average mNSS score of the rehabilitation group was significantly better than that of the model group. The average expression of Ngb in the model group was significantly higher than in the sham operation group. After the intervention, the average expression of SOD in the rehabilitation group was significantly higher than in the model group, while NO and MDA expression were significantly lower. After the intervention the average expression of NF-200 in the rehabilitation group was also significantly higher than in the model group.Conclusions:Rehabilitation training benefits the recovery of neurological function after cerebral infarction, at least in rats. The mechanism may be related to the upregulation of Ngb, alleviation of oxidative stress and enhancement of axonal regeneration in the peri-infarct cortex.

Advance of Netrin-1 for Protection and Repairment of Injuries after Cerebral Infarction (review) / 中国康复理论与实践

Netrin-1 may protect and repair the damage caused by cerebral infarction, in terms of inhibiting apoptosis and inflammatory, and promoting angiogenesis and axon regeneration, etc. Netrin-1 may associate with the pathogenesis and outcome of cerebral infarction. The application of Netrin-1 in clinic needs more researches.

Research progress on dental pulp stem cells in the repair of peripheral nerve injury / 口腔疾病防治

@#Peripheral nerve injury (PNI) is a common disease in the oral cavity that can easily lead to loss of function and abnormal appearance. The application of dental pulp stem cells (DPSCs) combined with tissue engineering in the repair of PNI is a research hotspot. DPSCs have the advantages of abundant sources, simple extraction, low immunogenicity and a high proliferation rate in vitro. They can differentiate into Schwann cells (SCs). SCs can induce autophagy and secrete key neurotrophic factors, such as nerve growth factor, brain-derived neurotrophic factor, ciliary neurotrophic factor and glial cell-derived neurotrophic factor. SCs are beneficial for the repair of nerve injury. DPSCs in different periods have differences in immune regulation, anti-inflammatory effects, expression of neural markers, angiogenesis and so on, which provide more diversified choices for nerve repair. At present, the introduction of tissue engineering provides a more controllable and improved microenvironment for DPSCs, which is conducive to the application and development of DPSCs in regenerative medicine and tissue engineering. However, there are still many problems to be solved, such as the selection of stem cells, functional link recovery, uncontrollable direction of axon regeneration, regulation of the peripheral nervous system and mechanism of repair.

Axonal cytomechanics in neuronal development

For more than a century, mechanical forces have been predicted to govern many biological processes duringdevelopment, both at the cellular level and in tissue homeostasis. The cytomechanics of the thin and highlyextended neuronal axons have intrigued generations of biologists and biophysicists. However, our knowledgeof the biophysics of neurite growth and development is far from complete. Due to its motile behavior and itsimportance in axonal pathfinding, the growth cone has received significant attention. A considerable amount ofinformation is now available on the spatiotemporal regulation of biochemical signaling and remodeling of thegrowth cone cytoskeleton. However, the cytoskeletal organization and dynamics in the axonal shaft werepoorly explored until recently. Driven by advances in microscopy, there has been a surge of interest in theaxonal cytoskeleton in the last few years. A major emerging area of investigation is the relationship betweenthe axonal cytoskeleton and the diverse mechanobiological responses of neurons. This review attempts tosummarize our current understanding of the axonal cytoskeleton and its critical role in governing axonalmechanics in the context of neuronal development.

Spinal cord homogenate promotes neurite outgrowth through activation of formyl peptide receptor 2 after spinal cord injury / 中国组织工程研究

BACKGROUND: Previous studies have observed the expression of formyl peptide receptor 2 in newly differentiated neurons from neural stem cells and confirmed that formyl peptide receptor 2 can promote the migration of neural stem/progenitor cells and induce them to differentiate into neurons. Formyl peptide receptor 2 ligands are present in damaged spinal cord tissues, but the binding of different ligands with FPR2 may lead to different and even opposite biological effects. OBJECTIVE: To investigate the neurite outgrowth after the binding of the ligands produced following spinal cord injury with formyl peptide receptor 2. METHODS: The fetal rat cerebral cortical neurons were extracted by enzymatic digestion. Spinal cord injury models were established in Sprague-Dawley rats, and the injured spinal cord homogenate was extracted. (1) Experiment 1: To observe the effect of the activation of formyl peptide receptor 2 on neurite outgrowth, the cells were divided into control group, formyl peptide receptor 2 blocker group (addition of WRW4), spinal cord homogenate group, spinal cord homogenate+WRW4 group. (2) Experiment 2: To observe the effect of blockade of AKT and ERK signaling pathways on neurite outgrowth after activation of formyl peptide receptor 2, the cells were divided into control group, AKT and ERK signaling pathway blocker group (addition of Ly294002+PD98059), spinal cord homogenate group, spinal cord homogenate+ Ly294002+PD98059 group. After 24 hours of culture, adherent neurons were treated with above-mentioned regimens for 7 days. Immunofluorescence staining with confocal microscope detection was used to observe the effect of spinal cord homogenate on neurite outgrowth via the activation of formyl peptide receptor 2. The cells were treated by the above-mentioned regimens for 30 minutes and phosphorylated protein levels were detected by western blot. The cells were treated with the above-mentioned regimens for 24 hours, and western blot assay was used to detect F-actin levels and observe the phosphorylation of key proteins in MAPK and PI3K/Akt pathways with the presence of formyl peptide receptor 2 specific blocker WRW4. RESULTS AND CONCLUSION: WRW4 could eliminate the effects of injured spinal cord homogenates on neurite outgrowth, including neurite length, the number of primary neurites, and the number of branch points. Spinal cord homogenate increased the phosphorylation of ERK1/2 and Akt in neurons, whereas this effect could be blocked by WRW4. Ly294002 and PD98059 could also eliminate the effects of homogenates on the neurite outgrowth. Spinal cord homogenate significantly increased the expression of F-actin in neurons, but this effect was blocked by WRW4. These results suggest that spinal cord homogenates can expedite neurite outgrowth by activating formyl peptide receptor 2, which may be related to the increased phosphorylation of ERK1/2 and Akt.

Difference in the culture of dorsal root ganglion cells in serum-free medium and serum medium / 中国组织工程研究

BACKGROUND: Both serum-free and serum media have been used to culture dorsal root ganglion cells, but the difference between the two remains unclear. OBJECTIVE: To explore whether serum-free medium can completely replace serum medium for culture of dorsal root ganglion cells. METHODS: The dorsal root ganglion of ICR mice at 8-10 weeks was taken and treated with collagenase and trypsin. After that, the mice were divided into the electroporation + serum group, electroporation + serum-free group, non-electroporation + serum group and non-electroporation + serum-free group. In the electroporation groups, the dorsal root ganglion cells were transfected with electroporation buffer and enhanced green fluorescent protein particles. Cells were cultured for three days. After Tuj1 antibody staining, in the non-electroporation + serum group and non-electroporation + serum-free group, axon branches, axon regeneration length, number of cell survival and the expression of proteins related to axon regeneration were counted. In the electroporation + serum group and electroporation + serum-free group, axon branches, length of axon regeneration, number of cell survival, and electroporation efficiency were measured. This study was approved by the Laboratory Animal Ethics Committee of the First Affiliated Hospital of Soochow University. RESULTS AND CONCLUSION: (1) In the non-electroporation + serum group and non-electroporation + serum-free group, there was no significant difference in axon branches, axon regeneration length, number of cell survival and the expression of axon regeneration related proteins (P > 0.05). (2) In the electroporation + serum group and electroporation + serum-free group, there was no significant difference in axon branches, axon regeneration length and electroporation efficiency (P > 0.05). Compared with electroporation + serum group, the number of cell survival of the electroporation + serum-free group was significantly lower (P 0.05). The number of cell survival of the non-electroporation + serum group was significantly higher than that of the electroporation + serum group (P < 0.05). (4) The results showed that, in the condition of non-electroporation, the absence of serum does not affect the culture of dorsal root ganglion in vitro, and serum-free medium can replace serum medium. However, under the condition of electroporation, the number of cell survival would be decreased without serum medium, suggesting that serum plays an important role in the culture of dorsal root ganglion in vitro under the condition of electroporation. Therefore, serum-free media cannot replace serum media.

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

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

Progress on axon regeneration in model organisms / 浙江大学学报·医学版

Different from neurons in the peripheral nervous system, mature neurons in the mammalian central nervous system often fail to regenerate after injury. Recent studies have found that calcium transduction, injury signaling, mitochondrial transportation, cytoskeletal remodeling and protein synthesis play essential roles in axon regeneration. Firstly, axon injury increases the intracellular concentration of calcium, and initiates the injury signaling pathways including cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) and dual leucine kinase (DLK), which are found to promote axon regeneration in multiple animal injury models. The second step for axonal regrowth is to rebuild growth cones. Overexpressing proteins that promote dynamics of microtubules and actin filaments is beneficial for the reassembly of cytoskeletons and initiation of new growth cones. Thirdly, mitochondria, the power factory for cells, also play important roles in growth cone formation and axonal extension. The last but not the least important step is the regulation of gene transcription and protein translation to sustain the regrowth of axons. This review summarizes important findings revealing the functions and mechanisms of these biological progresses.

Effect of Buyang Huanwu Tang on Axonal Regeneration of Rats After Ischemic Stroke Injury / 中国实验方剂学杂志

Objective:To investigate the effects of Buyang Huanwu Tang （BHT） on axonal regeneration and neurological rehabilitation of the rats suffering ischemic stroke （IS）. Method:A total of 180 SD rats were used to establish a middle cerebral artery infarction （MCAO） model. The animals that were successfully modeled were randomly divided into model group， BHT group （12 g·kg-1） and nimodipine group （20 mg·kg-1）， and a sham group was established， with 28 rats in each group. After seven-days intragastric administration of BHT， the animals were sacrificed. TTC staining was used to test cerebral infarction. Brain water content was measured to observe cerebral edema. Bielschowsky's silver staining and immunofluorescence were performed to observe axonal degeneration and the protein expression of neurofilament protein-200（NF-200）. Quantitative real-time polymerase chain reaction （PCR） was used to analyze the mRNA expression of repulsion oriented molecule a （RGMa）， Ras homologous enzyme （Rho）， Rho kinase （ROCK）， and collapsion response regulatory protein 2 （CRMP2）. Neurological function scores assay was used to examine neurological recovery. Result:Compared with sham group， the cerebral infarction volume and brain water content increased significantly（P<0.01）， and motor function was markablely decreased in the model group. Axonal degeneration and nerve fiber damage were obviously observed. Also， gene expression of axon growth-related protein was deviation from normal （P<0.01）. Compared with model group， the cerebral infarction rate （P<0.01）， brain water content （P<0.01） and axonal degeneration of BHT group and nimodipine group were significantly reduced. The expression of NF-200 was increased. Also， the mRNA expression of RGMa， Rho and ROCK was lower （P<0.05） while the mRNA expression of CRMP2 was higher （P<0.01）. And the neurological function was significantly improved （P<0.05）. Conclusion:BHT can promote axon regeneration after ischemic stroke injury by regulating the mRNA expression of axon growth-related protein， thereby improving nerve function.

Research progress of acupuncture and moxibustion on axon guidance cues / 针刺研究

Axon guidance cues includes Slit, Semaphorin, Ephrin and Netrin. They have the function of regulating the regeneration of axons and guiding the regenerated axons to the correct target. They can affect the nervous system, cardiovascular system, and participate in the proliferation and migration of tumor cells. The current research on the influence of acupuncture and moxibustion(mainly focusing on electroacupuncture) on axon guidance cues is limited to animal experiments. Electroacupuncture can treat diseases dominated by the nervous system by regulating the expression of axon guidance cues. This review summarizes the research progress of acupuncture and moxibustion on regulating axonal guidance cues, is hoped to provide references for the mechanism of acupuncture and moxibustion in treating nervous system disease and ideas for acupuncture treatment of diseases related to axon guidance cues.

Axon Guidance Molecules Guiding Neuroinflammation

Axon guidance molecules (AGMs), such as Netrins, Semaphorins, and Ephrins, have long been known to regulate axonal growth in the developing nervous system. Interestingly, the chemotactic properties of AGMs are also important in the postnatal period, such as in the regulation of immune and inflammatory responses. In particular, AGMs play pivotal roles in inflammation of the nervous system, by either stimulating or inhibiting inflammatory responses, depending on specific ligand-receptor combinations. Understanding such regulatory functions of AGMs in neuroinflammation may allow finding new molecular targets to treat neurodegenerative diseases, in which neuroinflammation underlies aetiology and progression.

Transport of alphaherpesviruses in neurons--axonal"shuttling" / 生物工程学报

After a long-term co-evolution, alphaherpesviruses have established mutual adaptability with their hosts. Some alphaherpesviruses have typical neurotropic characteristics, which have received extensive attention and in-depth research. Neurotropic alphaherpesviruses can break through the host barrier to infect neurons and multiply in large numbers in the neuron cell body to complete further proliferation or establish latent infection in the cell body. Either in the process of infecting neurons or further spreading, alphaherpesviruses will undergo transmission along axons or dendrites, so this process is an integral part of the life cycle of the viruses, and is also a key factor for the viruses to spread in nervous system. Therefore, studies on transportation of alphaherpesviruses in neurons will provide new insights of the viruses and promote the development of corresponding vaccines or targeted therapeutic pharmaceuticals. In addition, the neurotropism of alphaherpesviruses is conducive to the analysis of nerve circuits. Herein, the mechanisms of alphaherpesvirus transport in axons were reviewed, and the research direction and application of the transport of alphaherpesviruses in axons were put forward, which can provide reference for the prevention and control of alphaherpesviral infections.

Inhibitory effect of Sema3A on axonal growth of primary retinal ganglion cells in mice / 中华实验眼科杂志

Objective To investigate the effect of Semaphorin3A (Sema3A) on axon growth of primary retinal ganglion cells (RGCs) in mice.Methods C57/BL6 mice within 24 hours after birth were sacrificed and the eyeballs were removed,RGCs was isolated from retina and cultured in vitro.The primary cultured RGCs was identified by Brn3a immunofluorescence staining.Seven days after culture,the RGCs was divided into control group,0.05 μg/ml Sema3A group,0.10 μg/ml Sema3A group and 0.50 μg/ml Sema3A group,and the processing time was 2 hours.Immunofluorescence staining was used to detect the expression of neuron-specific marker β3-tubulin and dendritic marker MAP2,β3-tubulin+/MAP2-was identified as axons.The length of axons was measured by Image J software.The axon lengths of 0.10 μg/ml Sema3A group and control group at 0.5,1 and 2 hours after treatment were calculated.The primary cultured cells were divided into control group,Sema3A treatment group,Y27632 treatment group and combined treatment group according to different drugs.The average axon lengths were compared among the groups.The use and care of the animals complied with the Statement of the Association for Research in Vision and Ophthalmology (ARVO).Results Brn3a was positively expressed in primary cultured RGCs as a specific cell marker.Seven days after culture,RGCs tended to mature,with complete elongated neuronal processes and branches.The axon lengths of 0.05,0.10 and 0.50 μg/ml Sema3A groups were (69.35±1.49),(60.45±1.42) and (93.65±1.86) μm,which were significantly shorter than (109.80±2.29) μm of the control group (all at P＜0.01).The axon length of 0.10 μg/ml Sema3A group was (165.00 ±4.39)μm and (97.63 ±2.79)μm at 1 hour and 2 hours after treatment,respectively,which was significantly lower than (210.40 ±4.44) μm and (199.00 ± 4.36) μm of control group at corresponding time points (both at P＜0.01).There was a significant difference in the axon length of control group,Sema3A treatment group,mixed treatment group and Y27632 treatment group (F =142.50,P＜0.01).The RGC axon length of Sema3A treatment group was significantly lower than that of control group and combined treatment group (both at P＜0.01).Conclusions Sema3A can inhibit axon growth of primary retinal RGCs in mice,and ROCK signaling pathway inhibitors can alleviate such restrain effect.