Anatomical and histomorphometric study of the ulnar nerve at the wrist / Estudio anatómico e histomorfométrico del nervio ulnar en la muñeca

SUMMARY: The ulnar nerve (UN) is the main nerve responsible for innervation of the intrinsic musculature of the hand. It is of great importance to have a deep anatomical knowledge of the UN. The aim of this study is to enrich the knowledge of the UN anatomy at the wrist and provide useful reference information for clinical and surgical applications. In this descriptive cross-sectional study, 44 upper limbs of fresh cadavers were evaluated. The UN, the superficial branch of the ulnar nerve (SBUN), and the deep branch of the ulnar nerve (DBUN) were evaluated. Morphometric variables were measured using a digital caliper, and samples of nervous tissue were taken to evaluate the histomorphometry. Before entering the Guyon's canal, the UN had a diameter of 3.2 ± 0.4 mm. In 36 samples (82 %) the UN presented a bifurcation pattern and in the remaining 8 samples (18 %) a trifurcation was shown. The diameter of the DBUN was 1.9 ± 0.33 mm and that of the SBUN was 1.29 ± 0.22 mm. In the bifurcation patterns, the SBUN had a trunk of 5.71 ± 1.53 mm before bifurcating into the common digital nerve (fourth and fifth fingers) and an ulnar digital collateral nerve (fifth finger). The DBUN had an area of 2.84 ± 0.7 mm2 and was made up of 8 ± 1.4 fascicles and 3595 ± 465 axons. The SBUN area was 1.31 ± 0.27 mm2, it was made up of 6 ± 1.1 fascicles and 2856 ± 362 axons. The reported findings allow the hand surgeon to improve his understanding of the clinical signs of patients with UN pathologies at the wrist level and thus achieve greater precision while planning and performing surgical approaches and dissections.

El nervio ulnar (NU) es el principal nervio responsable de la inervación de la musculatura intrínseca de la mano. Es de gran importancia tener un profundo conocimiento anatómico del NU. El objetivo de este estudio fue enriquecer el conocimiento de la anatomía del NU en la muñeca y proporcionar información de referencia útil para aplicaciones clínicas y quirúrgicas. En este estudio descriptivo transversal se evaluaron 44 miembros superiores de cadáveres frescos. Se evaluó el NU, el ramo superficial del nervio ulnar (RSNU) y el ramo profundo del nervio ulnar (RPNU). Las variables morfométricas se midieron con un caliper digital y se tomaron muestras del nervio para evaluar la histomorfometría. Antes de ingresar al canal del nervio ulnar (canal Guyon), el ONU tenía un diámetro de 3,2 ± 0,4 mm. En 36 muestras (82 %) el ONU presentó un patrón de bifurcación y en las 8 muestras restantes (18 %) se presentó una trifurcación. El diámetro del RPNU fue de 1,9 ± 0,33 mm y el del RSNU de 1,29 ± 0,22 mm. En los patrones de bifurcación, el RSNU presentó un tronco de 5,71 ± 1,53 mm antes de bifurcarse en el nervio digital común (cuarto y quinto dedo) y un nervio digital colateral ulnar (quinto dedo). El RPNU tenía un área de 2,84 ± 0,7 mm2 y estaba formado por 8 ± 1,4 fascículos y 3595 ± 465 axones. El área del RSNU fue de 1,31 ± 0,27 mm2, estaba formado por 6 ± 1,1 fascículos y 2856 ± 362 axones. Los hallazgos reportados permiten al cirujano de mano mejorar su comprensión de los signos clínicos de los pacientes con patologías del NU a nivel de la muñeca y así lograr una mayor precisión en la planificación y realización de abordajes y disecciones quirúrgicas.

Effect of lappaconitine on neuropathic pain mediated by retrograde transport of P2X3 receptor in dorsal root ganglion neurons of rats with chronic constriction injury of the sciatic nerve / 中华创伤杂志

Objective:To investigate the effect of lappaconitine (LA) on neuropathic pain (NPP) mediated by retrograde transport of purinergic P2X3 receptor (P2X3R) in dorsal root ganglion (DRG) neurons of rats with chronic constriction injury (CCI) of the sciatic nerve.Methods:Seventy-two male healthy SD rats were selected to construct the NPP model following CCI of the sciatic nerve by ligating the right sciatic nerve. according to the random number table method. The rats were divided into CCI group, CCI+LA group and normal control group according to the random number table method, with 24 rats in each group. In normal control group, the right sciatic nerve was exposed without ligation. In CCI+LA group, the rats were given 2 g/L LA (ie, 4 mg/kg intravenously for once a day for one day only) after the same treatment as CCI group. Other two groups were injected with the identical amount of normal saline in the same way. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were evaluated before injury and at 2, 6, 12 and 24 hours after injury to evaluate the symptoms of neuralgia caused by nerve injury. The proximal and distal nerve fragments were collected in the three groups at 2, 6, 12 and 24 hours after injury. Western blotting was applied to analyze the expression of P2X3R at 2, 6, 12 and 24 hours after injury and the expression of neurotrophic factor (NGF) and tyrosine kinase receptor A (TrkA) at 24 hours after injury to evaluate the effect of LA on P2X3R, NGF and TrkA.Results:There were insignificant differences in MWT and TWL among all groups before injury (all P>0.05). Compared with normal control group, MWT and TWL were significantly decreased in CCI group and CCI+LA group at 2, 6, 12 and 24 hours after injury (all P<0.05 or 0.01). There were insignificant differences in MWT and TWL between CCI group and CCI+LA group at 2 and 6 hours after injury (all P>0.05), while MWT and TWL were significantly higher in CCI+LA group than those in CCI group at 12 and 24 hours after injury (all P<0.05 or 0.01). In the proximal sciatic nerve segment, Western blotting showed similar levels of P2X3R among all groups at 2, 6, 12 and 24 hours after injury (all P>0.05). In the distal sciatic nerve segment, Western blotting showed higher expression of P2X3R in CCI group than that in normal control group at 2, 6, 12, 24 hours after injury (all P<0.01), higher expression of P2X3R in CCI+LA group than that in normal control group at 2, 6 and 12 hours after injury (all P<0.05), similar expression of P2X3R expression between CCI+LA group and normal control group at 24 hours after injury ( P>0.05), similar expression of P2X3R between CCI group and CCI+LA group at 2 and 6 hours after injury (all P>0.05), and lower expression of P2X3R in CCI+LA group than that in CCI group at 12 and 24 hours after injury ( P<0.05 or 0.01). In the proximal and distal nerve fragments, the expression of NGF was lower in normal control group than that in CCI group and CCI+LA group ( P<0.05 or 0.01), but was similar between CCI group and CCI+LA group at 24 hours after injury ( P>0.05). In the proximal and distal nerve fragments, there were insignificant differences in the expression of TrkA among all groups at 24 hours after injury (all P>0.05). Conclusion:Early LA treatment after injury can alleviate mechanical and thermal hyperalgesia in NPP rats, which may be related to the reduction of P2X3R retrograde transport in DRG neuron axonal.

Sarm1-mediated neurodegeneration within the enteric nervous system protects against local inflammation of the colon

Axonal degeneration is one of the key features of neurodegenerative disorders. In the canonical view, axonal degeneration destructs neural connections and promotes detrimental disease defects. Here, we assessed the enteric nervous system (ENS) of the mouse, non-human primate, and human by advanced 3D imaging. We observed the profound neurodegeneration of catecholaminergic axons in human colons with ulcerative colitis, and similarly, in mouse colons during acute dextran sulfate sodium-induced colitis. However, we unexpectedly revealed that blockage of such axonal degeneration by the Sarm1 deletion in mice exacerbated the colitis condition. In contrast, pharmacologic ablation or chemogenetic inhibition of catecholaminergic axons suppressed the colon inflammation. We further showed that the catecholaminergic neurotransmitter norepinephrine exerted a pro-inflammatory function by enhancing the expression of IL-17 cytokines. Together, this study demonstrated that Sarm1-mediated neurodegeneration within the ENS mitigated local inflammation of the colon, uncovering a previously-unrecognized beneficial role of axonal degeneration in this disease context.

Advances about perineuronal nets in the repair of nerve function after spinal cord injury / 中国骨伤

Perineuronal nets (PNNs) is a complex network composed of highly condensed extracellular matrix molecules surrounding neurons. It plays an important role in maintaining the performance of neurons and protecting them from harmful substances. However, after spinal cord injury, PNNs forms a physical barrier that surrounds the neuron and limits neuroplasticity, impedes axonal regeneration and myelin formation, and promotes local neuroinflammatory uptake. This paper mainly describes the composition and function of PNNs of neurons and its regulatory effects on axonal regeneration, myelin formation and neuroinflammation after spinal cord injury.

Anatomical and ultrastructural sex differences in mean diameter and thickness of myelinated axons in adult rat corpus callosum / Diferencias sexuales anatómicas y ultraestructurales del diámetro medio y grosor de los axones mielinizados en el cuerpo calloso de ratas adultas

Sexual dimorphism exists at all levels of the nervous system. These sex differences could underlie genderrelated differences in behavior and neuropsychological function, as well as the gender differences in the prevalence of various mental disorders such as autism, attention deficit disorders, and schizophrenia. Myelination, on the other hand, is a unique cellular process that can have a dramatic impact on the structure and physiology of an axon and its surrounding tissue. The corpus callosum (CC) is the largest of the brain commissures, which connects the cerebral cortices of the two hemispheres, and provides interhemispheric connectivity for information transfer and processing between cortical regions. Variation in the axonal properties of CC will alter the interhemispheric connectivity. The CC consists of myelinated and unmyelinated axons, glial cells and blood vessels. Several functional studies have reported that the function of CC is associated with its axons density and myelination properties. The sexual dimorphism in the axonal content of the CC has always been controversial; hence, the aim of this study was to analyze the differences in axons' diameter and myelin sheath thickness of the CC between male and female rats. For this purpose, five pairs of adult male and female rats were perfused and the CC were removed and sectioned. Four sections from different subregions of the corpus callosum that represent the genu, anterior body, posterior body, and splenium of the CC were stained and electron microscopic images were captured using stereological guidelines. Later, the axons diameter and myelin sheath thickness for each subregion were calculated and compared between males and females. Our preliminary findings of the present study indicated region specific differences in the myelinated axon thickness and diameter in the CC between male and female rats.

El dimorfismo sexual existe en todos los niveles del sistema nervioso. Estas diferencias de sexo podrían ser la base de las diferencias de comportamiento y función neuropsicológica relacionadas con el sexo, así como las diferencias en la prevalencia de diversos trastornos mentales, como el autismo, los trastornos por déficit de atención y la esquizofrenia. La mielinización, por otro lado, es un proceso celular único que puede tener un impacto dramático en la estructura y fisiología de un axón y su tejido circundante. El cuerpo calloso (CC) es la mayor comisura cerebral, que conecta las cortezas cerebrales de ambos hemisferios, y proporciona la conectividad interhemisférica para la transferencia y el procesamiento de información entre regiones corticales. La variación en las propiedades axonales de CC alterará la conectividad interhemisférica. El CC consiste en axones mielinizados y no mielinizados, células gliales y vasos sanguíneos. Varios estudios funcionales han informado que la función de CC está asociada con la densidad de axones y las propiedades de mielinización. El dimorfismo sexual en el contenido axonal del CC siempre ha sido controvertido; por lo tanto, el objetivo de este estudio fue analizar las diferencias en el diámetro de los axones y el grosor de la vaina de mielina del CC entre ratas macho y hembra. Para este propósito, se perfundieron cinco pares de ratas macho y hembra adultas y se extrajeron y seccionaron las CC. Se tiñeron cuatro secciones de diferentes subregiones del cuerpo calloso que representan el genu, el cuerpo anterior, el cuerpo posterior y el esplenio y se capturaron imágenes de microscopía electrónicas utilizando referencias estereológicas. Posteriormente se calculó el diámetro de los axones y el grosor de la vaina de mielina para cada subregión y se compararon entre machos y hembras. Nuestros hallazgos preliminares del presente estudio indicaron diferencias específicas en el grosor y diámetro del axón mielinizado en el CC entre ratas macho y hembra.

Olfactory ensheathing cell transplantation promotes the ultrastructure repair at the lesion site of rat models of spinal cord injury / 中国组织工程研究

BACKGROUND: Olfactory ensheathing cell transplantation for treating spinal cord injury is an issue of concern, which mainly explores the changes of microenvironment after spinal cord injury. However, the effect of olfactory ensheathing cell transplantation on the ultrastructure of spinal cord after spinal cord injury is never reported. OBJECTIVE: To investigate the ultrastructure alterations of neurocytes, axons, myelin sheaths, synapses, and glial scar after spinal cord Injury, and the effect of olfactory ensheathlng cell transplantation on the protection and regeneration of nerve repair after spinal cord Injury. METHODS: The study was approved by the Ethical Committee of Biomedicine of Medical Department of Xi’an Jiaotong University, approval No. 2018-2048. Twenty female Sprague-Dawley rats were divided into three groups: Blank control group (n=4, complete laminectomy of T10, partial laminectomy of Tg and Tn), DF12 group (n=B, cordotomy+injection of DF12 solution), and olfactory ensheathing cell transplantation group (n=8, cordotomy+olfactory ensheathing cell transplantation). The spinal cord was removed under anesthesia to observe the ultrastructure alterations of neurocytes under transmission electron microscope at 1, 7, 28 and 56 days after injury. RESULTS AND CONCLUSION: (1) Compared with the blank control group, the organelles in the neurons of the injured lesions were significantly reduced, and the obvious changes were found in the ultrastructure of axon, synapses and myelin sheath in the DF12 group. In the olfactory ensheathing cell transplantation group, the organelles in the neurons of the injured lesions were significantly increased with obvious nucleolus, the regeneration of axon, myelin sheath and synapses were significantly promoted, and the glial scar was significantly decreased. (2) The degree of reaction of the astrocytes and pericytes in the olfactory ensheathing cell transplantation group was light. (3) These findings suggest that olfactory ensheathing cell transplantation can effectively protect the nerve tissues in the lesions after spinal cord injury, promote the regeneration of axon, myelin sheath and synapses, and inhibit the hyperplasia of astrocytes and pericytes, so that the post-injury microenvironment is available for the regeneration of neurons, axons and synapses.

Mechanism of bone marrow mesenchymal stem cells differentiation into functional neurons induced by glial cell line derived neurotrophic factor / 中国组织工程研究

BACKGROUND: Glial cell line derived neurotrophic factor (GDNF) plays an important role in inducing the differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro and promoting the regeneration of neuron axons. OBJECTIVE: To observe BMSCs differentiation induced by over-expression of GDNF gene, detect synaptic function of cells and expression of Wnt signaling pathway components after differentiation, and preliminarily explore the mechanism of BMSCs differentiation into mature neurons. METHODS: Rat BMSCs were isolated and cultured, and further divided into recombinant adenovirus-containing GDNF gene transfection group (Ad-GDNF-BMSCs), adenovirus transfection control group (Ad-BMSCs), and untransfected control group. The relative expression of GDNF gene in BMSCs of each group was detected by Q-PCR, and the expression of β-catenin, cyclin D1, NeuN and MAP-2 was detected by immunofluorescence technology in each group. High K+ stimulation induced cell depolarization response after differentiation, and FM4-64 marks synaptic vesicle activity of differentiated cells. RESULTS AND CONCLUSION: (1) The adenovirus-transfected gene had no significant negative effect on the proliferation of BMSCs. BMSCs could express endogenous GDNF gene continuously and at high levels. (2) Under the induction of GDNF gene, BMSCs could express neuron-specific protein NeuN after 3 days cultivation in vitro. The expression of β-catenin protein also could be detected in the cytoplasm of cells. After 7 days cultivation in vitro culture, BMSCs expressed the mature neuronal marker protein MAP-2, and the cell body contracted significantly. Neuron axon-like structures appeared around the cell body. Moreover, β-catenin and cyclin D1 were respectively detected in the cell cytoplasm and the nucleus, while the expression levels of NeuN, MAP-2, β-catenin, and cyclin D1 were not observed in Ad-BMSCs and untransfected control groups, and the cells remained spindle-shaped. (3) After 11 days of in vitro culture, the cells in the Ad-GDNF-BMSCs group showed typical neuronal processes or axons and connected to each other into a network structure, which could be labeled with FM4-64 to show red fluorescence, and induced by high K+ stimulation to induce action potentials in the cells. Synaptic vesicle activity in posterior axons showed FM4-64 red fluorescence gradually decaying. Under the same conditions, cells in the Ad-GDNF-BMSCs group and untransfected control group did not present FM4-64 fluorescently labeled synaptic vesicle activity. (4) Continuous GDNF induction can promote BMSCs differentiated into mature neurons with synaptic cycle function, and may be carried out through the classic Wnt/β-catenin signaling pathway.

Farnesylation-defective Rheb Increases Axonal Length Independently of mTORC1 Activity in Embryonic Primary Neurons

Rheb (Ras homolog enriched in the brain) is a small GTPase protein that plays an important role in cell signaling for development of the neocortex through modulation of mTORC1 (mammalian-target-of-rapamycin-complex-1) activity. mTORC1 is known to control various biological processes including axonal growth in forming complexes at the lysosomal membrane compartment. As such, anchoring of Rheb on the lysosomal membrane via the farnesylation of Rheb at its cysteine residue (C180) is required for its promotion of mTOR activity. To test the significance of Rheb farnesylation, we overexpressed a farnesylation mutant form of Rheb, Rheb C180S, in primary rat hippocampal neurons and also in mouse embryonic neurons using in utero electroporation. Interestingly, we found that Rheb C180S maintained promotional effect of axonal elongation similar to the wild-type Rheb in both test systems. On the other hand, Rheb C180S failed to exhibit the multiple axon-promoting effect which is found in wild-type Rheb. The levels of phospho-4EBP1, a downstream target of mTORC1, were surprisingly increased in Rheb C180S transfected neurons, despite the levels of phosphorylated mTOR being significantly decreased compared to control vector transfectants. A specific mTORC1 inhibitor, rapamycin, also could not completely abolish axon elongation characteristics of Rheb C180S in transfected cells. Our data suggests that Rheb in a non-membrane compartment can promote the axonal elongation via phosphorylation of 4EBP1 and through an mTORC1-independent pathway.

Advances in research on calcium channel inhibition mediating axonal stabilization for repair of optic nerve injury / 国际眼科杂志(Guoji Yanke Zazhi)

@#Optic nerve injury is a common nervous system disease. Its basic pathological features are axonal degeneration and apoptosis of retinal ganglion cells(RGCs), which causes numbers of symptoms including visual dysfunction. Axonal degeneration, including axonal selective degradation, Wallerian degeneration induced by axonal transection, and apoptosis-induced axonal degeneration(axonal apoptosis), is an important part of neurodevelopment, axonal remodeling, and injury response process. Axonal degeneration is one of the initial steps in many traumatic neurological disorders, and damaged axons are generally unable to regenerate, which leads to neuronal cell apoptosis. Neuronal apoptosis causing the degeneration of both cell bodies and axons commonly occurs during the development of brain, as a result of various neuronal damages. Studies in recent years have confirmed that calcium is the main regulator of axonal degeneration. When an optic nerve crush(ONC)occurs, the degree of acute axonal degeneration(AAD)can be reduced by using calcium channel inhibitors to prevent the influx of calcium ions into axons, which will also improve the survival rate of RGCs and accelerate the regeneration of axons.

Axonal injury and repair mechanism after ischemic stroke / 国际脑血管病杂志

The process of axonal injury after ischemic stroke can be roughly divided into three stages. Each stage has its different temporal and spatial pattern, as well as unique molecular cascade reactions. The process of axonal injury is also related to ischemic stroke subtype, and the treatment must be adjusted accordingly. Axon-glial intercellular neurotransmitter-energy metabolism coupling disorder and Ca2 + overload-mediated apoptosis-like degeneration are the main mechanisms of early axonal injury after stroke. Axonal regeneration and remyelination of damaged axons after stroke play an important role for the recovery of neurological function. Elucidating the axonal injury and repair mechanism after stroke can provide a new strategy for stroke treatment.

Molecular guidance cues in the development of visual pathway

70%-80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate nuclei (dLGN) and primary visual cortex (V1) thereafter, constituting the image-forming visual circuit. Molecular cues are one of the key factors to guide the wiring and refinement of the image-forming visual circuit during pre- and post-embryonic stages. Distinct molecular cues are involved in different developmental stages and nucleus, suggesting diverse guidance mechanisms. In this review, we summarize molecular guidance cues throughout the image-forming visual circuit, including chiasm determination, eye-specific segregation and refinement in the dLGN, and at last the reciprocal connections between the dLGN and V1.

Urgent requirements for clinical translational studies in restoration of injured optic nerve / 中华眼底病杂志

The optic nerve belongs to the central nervous system (CNS).Because of the lack of neurotrophic factors in the microenvironment of the CNS and the presence of myelin and glial scar-related inhibitory molecules,and the inherent low renewal potentials of CNS neurons comparing to the peripheral nerve system,it is difficult to spontaneously regenerate the optic nerve after injury.Protecting damaged retinal ganglion cells (RGCs),supplementing neurotrophic factor,antagonizing axon regeneration inhibitory factor,and regulating the inherent regeneration potential of RGCs can effectively promote the regeneration and repair of optic nerve.Basic research has made important progress,including the restoration of visual function,but there are still a lot of unsolved problems in clinical translation of these achievements,so far there is no ideal method of treatment of optic nerve injury.Therefore,it is rather urgent to strengthen the cooperation between basic and clinical research,to promote the transformation of basic research to the clinical applications as soon as possible,which will change the unsatisfactory clinical application status.

Antenatal taurine supplementation improves neural axon development in fetal rats with intrauterine growth restriction by inhibiting the activity of Rho-ROCK signaling pathway / 中华围产医学杂志

ObjectiveTo investigate the effects of prenatal taurine supplementation on the Rho-ROCK signaling pathway activity and synaptophysin (Syp) expression in brain tissues of rats with intrauterine growth restriction.MethodsEighteen pregnant Sprague-Dawley rats were randomly divided into control group, fetal growth restriction (FGR) group and taurine group, with six rats in each group. Low-protein diet was given in FGR and taurine groups to establish an FGR model. Taurine 300 mg/(kg·d) was supplemented from gestational day 12 until delivery in taurine group. The mRNA expression levels of neurite growth inhibitor-A(Nogo-A), neurite growth inhibitor receptor (NgR), Rho-A and ROCKⅡin fetal rat brain were detected using reverse transcriptase polymerase chain reaction (n=24), which are the key signaling molecules of the Rho-ROCK signal pathway. The protein expression levels of Nogo-A and NgR were detected by Western blot (n=12). The mean optical density in Nogo-A, NgR and Syp was determined by immunohistochemistry (n=18). One-way analysis of variance and LSD-t test were used for statistical analysis.Results(1) Expression of mRNA: the expression levels of Nogo-A, NgR, Rho-A and ROCKⅡ mRNA in fetal rat brain were 4.09±1.34, 3.01±0.77, 39.89±7.71 and 7.82±1.83, respectively in FGR group, and were significantly higher than in control group (1.00±0.13, 1.00±0.10, 1.02±0.30 and 1.00±0.10) (t=4.735, 5.204, 7.682 and 10.675, allP0.05). (2) Expression of protein by Western blot: the expressions of Nogo-A and NgR protein in fetal rat brain were 1.51±0.09 and 0.31±0.05 in FGR group, 0.82±0.06 and 0.06±0.01 in taurine group, and 1.04±0.10 and 0.09±0.12 in control group. The expression was significantly higher in FGR group than in control group (t=9.644 and 5.285, bothP0.05). (3) Positive expression of protein: the positive expressions of Nogo-A and NgR protein in fetal rat brain were 0.28±0.06 and 0.11±0.02 in FGR group, 0.10±0.02 and 0.04±0.01 in taurine group, and 0.07±0.01 and 0.04±0.01 in control group. The expression was significantly higher in FGR group than in control group (t=9.778 and 7.645, bothP0.05). The positive expression of Syp protein in fetal rat brain was 0.08±0.01 in FGR group, and was significantly lower than in control group (0.16±0.04,t=4.600,P0.05).ConclusionsPrenatal taurine supplementation can improve neural axon development via down-regulating the expressions of the key molecules of Rho-ROCK signal pathway in fetal rat brain tissue.

Expression change of microRNA-124 and its correlation with axon regeneration after traumatic brain injury in mice / 中华创伤杂志

Objective To observe the expression changes of microRNA-124(miRNA-124) following traumatic brain injury (TBI) in mice and investigate the correlation of miRNA-124 with neural axon regeneration.Methods Ninety-one C57BL/6 mice were assigned into TBI group (n =63) and control group (n =28) according to the random number table.Mice in TBI group were subjected to controlled cortical impact and euthanized at 12 hours and 1,3,7,14,21,28 days postinjury for the collection of brain tissue in the trauma zone.Mice in control group underwent craniectomy only.Trauma zone observation was done using the HE staining.Expression of miRNA-124 was detected using the real-time PCR.Levels of Nrp-1,Gap-43 and Tau were detected using the Western blot and immunohistochemical staining.Results After injtury,study of mice behavior and HE staining indicated the establishment of experimental model was successful.Expression of miRNA-124 reached the peak at 3 days postinjury (3.80 ± 0.22),expression of Nrp-1 reached the peak at 7 days postinjury (2.006 ±0.179),expression of Tau reached the peak at 14 days postinjury (2.063 ±0.172),and expression of Gap-43 sustained high level since 12 hours after injury(1.355 ± 0.093) (P ＜ 0.05).Count of axon marker positive cells in TBI group was the lowest at 1 day postinjury due to the direct damage and edema,and then slowly recovered.There was no significant difference in the count of axon marker positive cells between the two groups at 14,21 and 28 days postinjury (P ＞ 0.05),but the morphology in TBI group changed obviously.Although the positive cells of axon marker decreased at 1 day postinjury,expressions of miRNA-124,Nrp-1,Tau and Gap-43 in TBI group were significantly increased compared to the detections in control group (P ＜ 0.05).Conclusion Increased expression of miRNA-124 in trauma zone may closely related to axon regeneration after TBI in mice.

The different gene methylation levels of rat Schwann cells detected by MeDIP-Seq / 天津医药

Objective To explore the difference of DNA methylation levels between normal Schwann cells (NSCs) and activated Schwann cells (ASCs) in rats. Methods The adult Wistar rats were received sciatic nerve ligation and fed for 7 days. The ASCs and NSCs were separated from ligated sciatic nerves and brachial plexus respectively. Immunocytochemical staining of S-100 antibody was used to identify the cells. The growth condition of cells was detected by CCK-8 method. Methylated DNA immunoprecipitation sequencing (MeDIP-Seq) was applied to filter the differentially methylated regions in ASCs and NSCs. The distribution of differentially methylated genes related with axonal regeneration in chromosome was analyzed, and Gene ontology(GO)and PATHWAY analysis were also conducted. Results High purity of ASCs and NSCs were obtained successfully, which were both positive for S-100 antibody. In the same culture condition, ASCs showed a faster proliferation than that of NSCs. A total of 177 176 differentially methylated regions were found by MeDIP-Seq. Among them, 1 097 were located in the promoter (≤1 kb), 1 136 in the promoter (1-2 kb) and 567 on the CpG. After functional annotation of differentially methylated genes, 214 differentially methylated genes related with axonal regeneration were found in ASCs and NSCs. Compared with NSCs, 191 genes were up-regulated and 23 genes were down-regulated in ASCs. These genes were located on different chromosomes, most of which on chromosome 12 (22 genes) and the least on chromosomes M (2 genes). GO analysis indicated that the differential methylated genes were involved in axon growth, axon formation, axon elongation and axon guidance. The MAPK, cell adhesion molecules, Ras signaling pathway may be related with the differential methylated genes. Conclusion The methylation levels between ASCs and NSCs are significantly different, which are probably related with axon regeneration.

Cellular prion protein-mediated hippocampal neuron axon elongation impairment involved in cognitive impairment induced by sleep deprivation / 中华神经科杂志

Objective To investigate the effect of rapid eye movement (REM) sleep deprivation on spatial memory and hippocampal cellular prion protein (PrPC) expression and to explore the underlying mechanism of cognitive impairment induced by sleep deprivation.Methods Adult Sprague-Dawley rats were sorted by weight,randomly divided into three groups:the cage control (CC) group,the tank control (TC) group,and the sleep deprivation (SD) group.Rats were deprived of REM sleep for 72 h using the modified multiple platform method.The Morris water maze task was used to assess hippocampal-dependent spatial memory.After sleep deprivation,the rats were sacrificed and their brain tissue was analyzed for PrPC protein expression via Western blotting.Hippocampal neuron axon elongation was examined as well after lentivector-mediated RNA interference (RNAi) of PrPC in primary cultured rat hippocampal neurons.Results REM sleep deprivation for 72 h resulted in spatial memory impairment.The number of times of rats passing through the platform was decreased significantly in the SD group (3.17 ±0.95) compared with the CC (7.17 ±0.95) and TC (6.50 ±0.62) groups (Z =2.026 6,Z =2.026 6,P ＜0.05),the mean value of proximity to the platform (mm) was greater for rats of the SD group (711.74 ± 33.99) compared to those of theCC (592.32±31.31) andTC (580.86±11.36) groups (Z=-2.001 6,Z=-2.4820,P ＜ 0.05).REM sleep deprivation for 72 h resulted in reduced PrPC level in the hippocampus (0.33 ± 0.10) compared with the CC (1.01 ±0.33) and TC (0.96 ±0.27) groups (Z=2.152 9,Z=2.152 9,P ＜ 0.05).In primary cultured hippocampal neurons,axon elongation(μm) was inhibited 7 days in infected neurons (326.28 ± 12.53) compared with normal (555.00 ±30.43) or negative control (558.70 ±23.10) cells (Z =4.768 4,Z =4.877 0,P ＜ 0.05).Conclusion These findings suggest that PrPC-mediated hippocampal neuron axon elongation inhibition is probably involved in spatial memory impairment induced by sleep deprivation in rats.

Morphological Analysis of the Myelinated Parent Axons that Innervate Rat Upper Molar Pulps in the Trigeminal Ganglion

Previous studies suggested that myelinated axons innervating rat molar pulps undergo morphological changes in their peripheral course. However, little information is available on the morphological feature of the parent axons at the site of origin. We therefore investigated the size of the myelinated parent axons and their morphological features at the proximal sensory root of the trigeminal ganglion by horseradish peroxidase (HRP) injection into rat upper molar pulps and subsequent light and electron microscopy. A total of 248 HRP-labeled myelinated axons investigated were highly variable in the size. Fiber area, fiber diameter, axon area (axoplasm area), axon diameter (axoplasm diameter), and myelin thickness were 11.32 +/- 8.36 microm2 (0.80~53.17 microm2), 3.99 +/- 1.53 microm (1.08~9.26 microm), 8.70 +/- 6.30 microm2 (0.70~41.83 microm2), 3.13 +/- 1.13 microm (0.94~7.20 microm) and 0.43 +/- 0.23 microm (0.07~1.06 microm), respectively. The g-ratio (axon diameter / fiber diameter) of the labeled axons was 0.79 +/- 0.05 (0.61~0.91). Axon diameter was highly correlated with myelin thickness (correlation coefficients,r=0.83) but little correlated with g-ratio (r=-0.33) of individual myelinated parent axons. These results indicate that myelin thickness of the myelinated parent axons innervating rat molar pulps increase with increasing axon diameter, thus maintaining a constant g-ratio.

Application research of MR diffusion tensor imaging in diagnosis traumatic axonal injury / 中国医师杂志

Objective To explore the value of MR diffusion tensor imaging ( DTI) in diagnosis of traumatic Axonal injury ( TAI) .Methods Twenty nine patients with traumatic brain injury ( TBI) and matched 22 control subjects were performed with DTI . Fractional anisotropy ( FA) was calculated from semioval center , corpus callosum , internal capsule and pons of controls and TBI pa-tients.According to Glasgow Score (GCS), TBI patients were divided into mild group (GCS≥13) and moderate-severe group (GCS≤12), each group compared with control group in FA value .The correlation between FA values in different regions and GCS score were analyzed in DTI group .Results FA value of semioval center was decreased in mild DTI group ( P <0.01 ) .FA values of semio-val center , corpus callosum , and internal capsule were decreased in moderate-severe DTI group ( P <0.05 ) .The FA values in semio-val center , corpus callosum , and internal capsule were positively correlated with GCS score in TBI group ( P <0.05 ) .Conclusions DTI is sensitive to detect the traumatic axonal injury??Changes of FA value in ROIs can access the severity of axonal injury ?? which ishelpful for diagnosis earlier and improving prognosis.

Role and mechanism of retinoic acid in axonal regeneration / 中国组织工程研究

BACKGROUND:Retinoic acid signaling pathways is very important in the formation pf nervous system, specialization of neurons and outgrowth of axons. The recent studies show that, retinoic acid plays an important role in the process of axonal regeneration, but few research reports its exact molecular mechanism. OBJECTIVE:To analyze and summarize the mechanism underlying retinoic acid signaling pathways in the process of axonal regeneration. METHODS:A computer-based online research was conducted among the VIP, CNKI, PubMed, BioMed Centeral, Springer, The Free Medical Journals, EBSCO and Foreign Journals Integration System between January 2000 and December 2013, with the key words of“retinoic acid, the central nervous system, nerve damage, axon regeneration, and mechanism”in Chinese and English. A total of 43 studies addressing the molecular mechanism of retinoic acid in axonal regeneration were screened. According to the supplementary documents, another five references were added. Repetitive research and atypical reports were excluded. RESULTS AND CONCLUSION:Fol owing acute central nervous system injury, axonal regeneration and functional recovery are extremely limited. For proper functionality fol owing injury, axons must regrow, reinnervate their targets, and remyelinate their axons. When the central nervous system injuries occur, retinoic acid signaling pathways express transcription factor retinoic acid receptorβ2 to induce axonal regeneration fol owing injury;in dorsal root ganglion neurons, cAMP levels are greatly increased by lentiviral retinoic acid receptorβ2 expression and contribute to neurite outgrowth. More recently, retinoic acid-retinoic acid receptorβ2 pathways directly transcriptional y repress a member of the inhibitory Nogo receptor complex, Lingo-1, under an axonal growth inhibitory environment in vitro as wel as fol owing spinal cord injury in vivo. Through these molecular mechanisms, retinoic acid signaling pathways play its important role in the process of axonal regeneration.

Axonal regeneration style and speed after axonal transaction: a preliminary study / 中华创伤杂志

ObjectiveTo establish a central nervous system axonal mechanical transection model in vitro and observe the axonal regeneration style and speed following the transection. MethodsThe cortical explants the mice were cultured in vitro,of which the axon and dendrite parts were marked using immunofluorescence.The model was built by mechanically transecting the axons and removing the severed axons.The axonal regeneration style was observed by tracing the undeveloped cellular bodies adhering to the residual axonal surface.The growth speed of the regenerated axons and normal axons were measured as well.Results ( 1 ) After mechauically transecting the axons of explants,the axonal regeneration was largely founded at the transected line.The undeveloped cellular bodies went over the transected line and spread to the distal area with axonai regeneration. (2) The axonal growth speed was (118 ± 32) μm/d and (72 ±41) μm/d in the transection group,but was (41 ± 17) μm/d and (32 ± 19) μm/d in the control group at 24 and 48 hours respectively. ConclusionThe regeneration style of the transected axons is the extension of the axonal stumps,rather than sprouting growth,and the growth speed is faster than that of the normal axons.