Myelin Structure Research Articles

Buyang huanwu decoction promotes remyelination via miR-760-3p/GPR17 axis after intracerebral hemorrhage

Ethnopharmacological relevanceThe repairment of myelin sheaths is crucial for mitigating neurological impairments of intracerebral hemorrhage (ICH). However, the current research on remyelination processes in ICH remains limited. A representative traditional Chinese medicine, Buyang Huanwu decoction (BYHWD), shows a promising therapeutic strategy for ICH treatment. Aim of the studyTo investigate the pro-remyelination effects of BYHWD on ICH and explore the underlying mechanisms. Materials and methodsThe collagenase-induced mice ICH model was created for investigation. BYHWD's protective effects were assessed by behavioral tests and histological staining. Transmission electron microscopy was used for displaying the structure of myelin sheaths. The remyelination and oligodendrocyte differentiation were evaluated by the expressions of myelin proteolipid protein (PLP), myelin basic protein (MBP), MBP/TAU, Olig2/CC1, and PDGFRα/proliferating cell nuclear antigen (PCNA) through RT-qPCR and immunofluorescence. Transcriptomics integrated with disease database analysis and experiments in vivo and in vitro revealed the microRNA-related underlying mechanisms. ResultsHere, we reported that BYHWD promoted the neurological function of ICH mice and improved remyelination by increasing PLP, MBP, and TAU, as well as restoring myelin structure. Besides, we showed that BYHWD promoted remyelination by boosting the differentiation of PDGFRα+ oligodendrocyte precursor cells into olig2+/CC1+ oligodendrocytes. Additionally, we demonstrated that the remyelination effects of BYHWD worked by inhibiting G protein-coupled receptor 17 (GPR17). miRNA sequencing integrated with miRNA database prediction screened potential miRNAs targeting GPR17. By applying immunofluorescence, RNA in situ hybridization and dual luciferase reporter gene assay, we confirmed that BYHWD suppressed GPR17 and improved remyelination by increasing miR-760-3p. ConclusionsBYHWD improves remyelination and neurological function in ICH mice by targeting miR-760-3p to inhibit GPR17. This study may shed light on the orchestration of remyelination mechanisms after ICH, thus providing novel insights for developing innovative prescriptions with brain-protective properties.

Early exercise intervention promotes myelin repair in the brains of ischemic rats by inhibiting the MEK/ERK pathway.

Our previous studies have shown that early exercise intervention after stroke increases neural activity and synaptic plasticity and promotes the recovery of nerve fiber bundle integrity in the brain. However, the effect of exercise on the repair of myelin in the brain and the related mechanism are still unclear. In this study, we randomly divided the rats into three groups. Before and after 28 days of intervention, body weight, nerve function, the infarct size, white matter fiber bundle integrity, and nerve myelin structure and function were observed by measuring body weight, analysis of modified neurological severity score, CatWalk gait analysis, MRI, luxol fast blue staining, immunofluorescence, and transmission electron microscopy. Changes in the expression of proteins in the MEK/ERK pathway were assessed. The results showed that early exercise intervention resulted in neurological recovery, decreased the infarct volume and increased nerve fiber integrity, the myelin coverage area, myelin basic protein (MBP) fluorescence intensity expression, and myelin thickness. Furthermore, the expression level of MBP was significantly increased after early exercise intervention, while the expression levels of p-MEK1/2 and p-ERK1/2 were significantly reduced. In the cell study, MBP expression levels were significantly higher in the oxygen and glucose deprivation and administration group.In summary, early exercise intervention after stroke can promote myelin repair by inhibiting the MEK/ERK signaling pathway.

Nanoscale myelinogenesis image in developing brain via super-resolution nanoscopy by near-infrared emissive curcumin-BODIPY derivatives

Understanding the intricate nanoscale architecture of neuronal myelin during central nervous system development is of utmost importance. However, current visualization methods heavily rely on electron microscopy or indirect fluorescent method, lacking direct and real-time imaging capabilities. Here, we introduce a breakthrough near-infrared emissive curcumin-BODIPY derivative (MyL-1) that enables direct visualization of myelin structure in brain tissues. The remarkable compatibility of MyL-1 with stimulated emission depletion nanoscopy allows for unprecedented super-resolution imaging of myelin ultrastructure. Through this innovative approach, we comprehensively characterize the nanoscale myelinogenesis in three dimensions over the course of brain development, spanning from infancy to adulthood in mouse models. Moreover, we investigate the correlation between myelin substances and Myelin Basic Protein (MBP), shedding light on the essential role of MBP in facilitating myelinogenesis during vertebral development. This novel material, MyL-1, opens up new avenues for studying and understanding the intricate process of myelinogenesis in a direct and non-invasive manner, paving the way for further advancements in the field of nanoscale neuroimaging.Graphical

Myelin figures from microbial glycolipid biosurfactant amphiphiles

AbstractMyelin figures (MFs)—cylindrical lyotropic liquid crystalline structures consisting of concentric arrays of bilayers and aqueous media—arise from the hydration of the bulk lamellar phase of many common amphiphiles. Prior efforts have concentrated on the formation, structure, and dynamics of myelin produced by phosphatidylcholine (PC)‐based amphiphiles. Here, we study the myelinization of glycolipid microbial amphiphiles, commonly addressed as biosurfactants, produced through the process of fermentation. The hydration characteristics (and phase diagrams) of these biological amphiphiles are atypical (and thus their capacity to form myelin) because unlike typical amphiphiles, their molecular structure is characterized by two hydrophilic groups (sugar, carboxylic acid) on both ends with a hydrophobic moiety in the middle. We tested three different glycolipid molecules: C18:1 sophorolipids and single‐glucose C18:1 and C18:0 glucolipids, all in their nonacetylated acidic form. Neither sophorolipids (too soluble) nor C18:0 glucolipids (too insoluble) displayed myelin growth at room temperature (RT, 25°C). The glucolipid C18:1 (G‐C18:1), on the other hand, showed dense myelin growth at RT below pH 7.0. Examining their growth rates, we find that they display a linear (L, myelin length; t, time) growth rate, suggesting ballistic growth, distinctly different from the dependence, characterizing diffusive growth such as what occurs in more conventional phospholipids. These results offer some insight into lipidic mesophases arising from a previously unexplored class of amphiphiles with potential applications in the field of drug delivery.

Impairments of cerebellar structure and function in a zebrafish KO of neuropsychiatric risk gene znf536

Genetic variants in ZNF536 contribute to the risk for neuropsychiatric disorders such as schizophrenia, autism, and others. The role of this putative transcriptional repressor in brain development and function is, however, largely unknown. We generated znf536 knockout (KO) zebrafish and studied their behavior, brain anatomy, and brain function. Larval KO zebrafish showed a reduced ability to compete for food, resulting in decreased total body length and size. This phenotype can be rescued by segregating the homozygous KO larvae from their wild-type and heterozygous siblings, enabling studies of adult homozygous KO animals. In adult KO zebrafish, we observed significant reductions in anxiety-like behavior and social interaction. These znf536 KO zebrafish have decreased cerebellar volume, corresponding to decreased populations of specific neuronal cells, especially in the valvular cerebelli (Va). Finally, using a Tg[mbp:mgfp] line, we identified a previously undetected myelin structure located bilaterally within the Va, which also displayed a reduction in volume and disorganization in KO zebrafish. These findings indicate an important role for ZNF536 in brain development and implicate the cerebellum in the pathophysiology of neuropsychiatric disorders.

A generalizable deep voxel-guided morphometry algorithm for the detection of subtle lesion dynamics in multiple sclerosis

IntroductionMultiple sclerosis (MS) is a chronic neurological disorder characterized by the progressive loss of myelin and axonal structures in the central nervous system. Accurate detection and monitoring of MS-related changes in brain structures are crucial for disease management and treatment evaluation. We propose a deep learning algorithm for creating Voxel-Guided Morphometry (VGM) maps from longitudinal MRI brain volumes for analyzing MS disease activity. Our approach focuses on developing a generalizable model that can effectively be applied to unseen datasets.MethodsLongitudinal MS patient high-resolution 3D T1-weighted follow-up imaging from three different MRI systems were analyzed. We employed a 3D residual U-Net architecture with attention mechanisms. The U-Net serves as the backbone, enabling spatial feature extraction from MRI volumes. Attention mechanisms are integrated to enhance the model's ability to capture relevant information and highlight salient regions. Furthermore, we incorporate image normalization by histogram matching and resampling techniques to improve the networks' ability to generalize to unseen datasets from different MRI systems across imaging centers. This ensures robust performance across diverse data sources.ResultsNumerous experiments were conducted using a dataset of 71 longitudinal MRI brain volumes of MS patients. Our approach demonstrated a significant improvement of 4.3% in mean absolute error (MAE) against the state-of-the-art (SOTA) method. Furthermore, the algorithm's generalizability was evaluated on two unseen datasets (n = 116) with an average improvement of 4.2% in MAE over the SOTA approach.DiscussionResults confirm that the proposed approach is fast and robust and has the potential for broader clinical applicability.

Co-treatment of Astragaloside IV with Vitamin D in Diabetic Peripheral Neuropathic Rats: Protective Effects and Potential Mechanisms.

The potential mechanism underlying the protective effect of Astragaloside IV (AS-IV) co-treatment with 1, 25-dihydroxy-vitamin D (Vit-D) on neuropathy in diabetic high-fat rats was investigated. The rat diabetic hyperlipidemia (DH) model was established via streptozotocin and a high-fat diet (HFD). After co-treatment (of AS-IV and Vit-D at respective doses of 50 mg/kg via oral gavage and 30000 IU/kg via intramuscular injection), blood glucose levels, markers of inflammation and oxidative stress, as well as apoptosis and histopathology were evaluated with appropriate techniques. Co-treatment could effectively reduce blood glucose levels substantially (p< 0.01), improve weight loss, and decrease oral glucose tolerance. Reduced respective sensory and motor nerve conduction velocities in rats were substantially improved (p<0.01) after co-treatment. Also, we observed obvious improvement in DH-induced injured nerve fiber myelin structure and other organ pathologies in co-treated rats. Besides, we observed up-regulated expressions of peroxisomal-proliferator activated receptor-alpha (PPAR-α) and Vit-D receptors (VDR) (p< 0.01) through the western blotting technique. Using the same technique, we also discovered reduced levels of interleukin (IL)1 beta, IL-6, and tumor necrosis factor-alpha, coupled with increased IL-10 and superoxide dismutase levels (p< 0.01). Importantly, co-treatment could effectively exert antioxidative and anti-inflammatory effects. Also, co-treatment resulted in the up-regulation of PPAR-α and VDR expressions, inhibition of the renin-angiotensin-aldosterone system, and promotion of β-cell sensitivity to insulin. The combined application of AS-IV and Vit-D exhibited health effects such as anti-oxidation, regulation of inflammatory factors, and promotion of cell repair, which may be considered as the mechanisms underlying treatment of diabetic peripheral neuropathy and improvement in biochemical indicators.

Adolescent binge ethanol impacts H3K9me3-occupancy at synaptic genes and the regulation of oligodendrocyte development.

Binge drinking in adolescence can disrupt myelination and cause brain structural changes that persist into adulthood. Alcohol consumption at a younger age increases the susceptibility of these changes. Animal models to understand ethanol's actions on myelin and white matter show that adolescent binge ethanol can alter the developmental trajectory of oligodendrocytes, myelin structure, and myelin fiber density. Oligodendrocyte differentiation is epigenetically regulated by H3K9 trimethylation (H3K9me3). Prior studies have shown that adolescent binge ethanol dysregulates H3K9 methylation and decreases H3K9-related gene expression in the PFC. Here, we assessed ethanol-induced changes to H3K9me3 occupancy at genomic loci in the developing adolescent PFC. We further assessed ethanol-induced changes at the transcription level with qPCR time course approaches in oligodendrocyte-enriched cells to assess changes in oligodendrocyte progenitor and oligodendrocytes specifically. Adolescent binge ethanol altered H3K9me3 regulation of synaptic-related genes and genes specific for glutamate and potassium channels in a sex-specific manner. In PFC tissue, we found an early change in gene expression in transcription factors associated with oligodendrocyte differentiation that may lead to the later significant decrease in myelin-related gene expression. This effect appeared stronger in males. Further exploration in oligodendrocyte cell enrichment time course and dose response studies could suggest lasting dysregulation of oligodendrocyte maturation at the transcriptional level. Overall, these studies suggest that binge ethanol may impede oligodendrocyte differentiation required for ongoing myelin development in the PFC by altering H3K9me3 occupancy at synaptic-related genes. We identify potential genes that may be contributing to adolescent binge ethanol-related myelin loss.

Spontaneous remyelination following dimethyl sulfoxide-induced demyelination is accompanied by behavioral and neurological alteration in mice

Introduction: Dimethyl sulfoxide (DMSO) is a commonly used solvent that can be applied in experimental studies for preparation of hydrophobic solutions as well as in capacity of a cryopreservative in transplantology. According to modern data acquired from in vitro experiments, DMSO is able to change the structure of myelin by decreasing synthesis of its main components and inhibiting oligodendrocyte genesis. Aim of the study: We studied influence of DMSO on anxiety and compulsive-like behavior, pain perception, motor coordination and myelin quantity in the corpus callosum of the C57BL/6 mice brain after prolonged oral administration of the solvent and 4 weeks after administration was stopped. Materials and Methods: All the experiments were conducted on male inbreed C57BL/6 mice. DMSO was added to drinking water to achieve 0.01% concentration, and the obtained solution was administered ad libitum for 6 weeks. After 6 weeks of administration of DMSO and 4 weeks after administration of DMSO was stopped, anxiety-like behavior in open field test, compulsive-like behavior in marble burying test, motor coordination in rotarod test, pain perception in tail-immersion test, as well as myelin quantity in the corpus callosum were evaluated. Results: It was established that DMSO consumed for 6 weeks was associated with decrease in the myelin quantity in thecorpus callosum and thermal hyperalgesia in tail-immersion test. During 4-week period after DMSO administration was stopped, attenuation of demyelination was observed, followed by an increase in thermal hyperalgesia in tail-immersion test, as well as vertical locomotion and exploratory activity in open field test. Conclusions: 6-week ad libitum administration of 0.01% DMSO solution was associated with demyelination in corpus callosum of С57BL/6 mice, followed by thermal hyperalgesia. Cessation of DMSO led to spontaneous remyelination with an increase in thermal hyperalgesia, vertical locomotion and exploratory activity of mice.

Recording changes in biochemical parameters &lt;i&gt;in vivo&lt;/i&gt; in the ischemic stroke model

Stroke is a significant and socially insidious disease that ranks second among fatal diseases according to the World Health Organization [1]. Understanding the molecular mechanisms behind the pathogenesis of this ailment will enable the development of more effective preventative measures and treatment strategies to minimize the negative consequences of stroke. Despite the abundance of experimental data, most of which were acquired indirectly, the study of the dynamics of biochemical parameters in brain tissue in real time during the acute phase of ischemic stroke is difficult. The use of genetically-encoded sensors creates novel possibilities for monitoring alterations in different biochemical and metabolic parameters in vivo tissues. In this study, we evaluated pH changes, hydrogen peroxide production (an important type of biologically active ROS), and polysulfide synthesis in various types of brain tissue cells of SHR rats during the development of ischemic stroke in real time using sensors such as SypHer3s (for pH detection), HyPer7 (for H2O2 detection), and PersIc (for polysulfide detection). Middle cerebral artery occlusion was used to simulate an ischemic stroke. The in vivo sensor signals were registered with a fiber optic setup that was created in the laboratory of spectroscopy and nonlinear optics at Moscow State University. The studies revealed that in the acute phase of stroke, acidosis occurred in the cytoplasm of neurons in the caudate nucleus, the epicenter of ischemia. The pH mutated from 7.25±0.08 to 6.7±0.15 within the first few seconds after arterial occlusion initiation. A gradual increase in pH was observed after the initial drop, which persisted throughout reperfusion but did not return to the original value in all animals. In the penumbra zone, a wave-like shift in sensor signal was detected, whereas no change in sensor signal was noted in the healthy hemisphere. Investigation of the dynamics of H2O2 formation in the mitochondrial matrix of caudate neurons revealed minimal sensor oxidation during ischemia/reperfusion in the acute phase of stroke, indicating low ROS production. Nevertheless, a substantial increase in the sensor signal was detected after 24 hours following the surgery. Thus, the confirmation of oxidative stress development in the affected hemisphere differed from the commonly accepted view in terms of its dynamics. Previously, it was believed that excessive production of H2O2 leading to oxidative stress and related brain cell death occurred primarily in the acute phase. However, a comparison of hydrogen peroxide production dynamics in neurons and astrocytes revealed differences between these cell populations. It was discovered that as early as 12 hours after middle cerebral artery occlusion, the sensor signal in astrocytes increased more intensely than in neurons. This trend persisted until the end of the measurements, 40 hours after surgery. The observed distinctions may stem from glial cells’ protective function in counteracting the harmful consequences of hydrogen peroxide on neurons, along with their contribution to maintaining the myelin structure in the brain. Additionally, the role of astrocytes in neuroinflammation development is noteworthy. Reactive sulfur species, in addition to reactive oxygen species, appear to be significant contributors to the development of pathological processes. The PersIc sensor signal measurement did not show any disparities between the caudate nucleus of the healthy hemisphere and the hemisphere affected by stroke development in terms of polysulfide and persulfide appearance detection. However, the area surrounding the core infarction is noteworthy due to the observed bouts of acidosis using the SypHer3s sensor. Our findings suggest a potential association between these bouts, spreading depolarization, changes in calcium concentration, and the development of neuroinflammation. These reactions may ultimately lead to the synthesis of polysulfides, known modulators of inflammatory reactions. Thus, our data provides valuable additions to the existing knowledge on metabolic changes that take place during the progression of ischemic brain injury.

Myelin repair of spinal cord injury in adult mice induced by treadmill training upregulated peroxisome proliferator-activated receptor gamma coactivator 1 alpha.

Growing evidence has proven the efficacy of physical exercise in remyelination and motor function performance after spinal cord injury (SCI). However, the molecular mechanisms of treadmill training on myelin repair and functional recovery after SCI have not yet been fully studied. Here, we explored the effect of treadmill training on upregulating peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α)-mediated myelin repair and functional recovery in a mouse model of thoracic T10 contusion injury. A 4-week treadmill training scheme was conducted on mice with SCI. The expression levels of oligodendrogenesis-related protein and PGC1α were detected by immunofluorescence, RNA fluorescence in situ hybridization and western blotting. Transmission electron microscopy (TEM) was used to observe myelin structure. The Basso Mouse Scale (BMS) and CatWalk automated gait analysis system were used for motor function recovery evaluation. Motor evoked potentials (MEPs) were also identified. In addition, adeno-associated virus (AAV)-mediated PGC1α knockdown in OLs was used to further unravel the role of PGC1α in exercise-induced remyelination. We found that treadmill training boosts oligodendrocyte precursor cells (OPCs) proliferation, potentiates oligodendrocytes (OLs) maturation, and increases myelin-related protein and myelin sheath thickness, thus impelling myelin repair and hindlimb functional performance as well as the speed and amplitude of nerve conduction after SCI. Additionally, downregulating PGC1α through AAV attenuated these positive effects of treadmill training. Collectively, our results suggest that treadmill training enhances remyelination and functional recovery by upregulating PGC1α, which should provide a step forward in the understanding of the effects of physical exercise on myelin repair.

Astrocytes: Lessons Learned from the Cuprizone Model.

A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.

CNSC-31. BESPOKE THREE- PHOTON MICROSCOPY AND ANALYSIS ENABLE DEEP INTRAVITAL BRAIN TUMOR IMAGING

Abstract Glioblastoma is the most common primary brain tumor with a poor prognosis due to its aggressive invasiveness, inevitable recurrence, and therapy resistance. One hallmark of the disease is its whole brain dissemination via preexisting brain structures like blood vessels or white matter tracts. While intravital glioblastoma imaging has been limited to the superficial cortical layers, we developed a method of three photon microscopy allowing the investigation of glioblastoma invasion and colonization in the white matter up to a depth of 1.2 mm over extended time periods. Our method, combining adaptive optics 3P imaging, customized deep learning- based denoising and machine learning segmentation, enables longitudinal volumetric multicolor imaging, being able to distinguish GBM cell signal from myelin structures as well as blood vessel signal. Thus, GBM cells and their interactions with and influence on the microenvironment within the white matter can be investigated longitudinally. We found that compared to cortical invasion, a majority of GBM cells in the corpus callosum are aligned with myelinated axonal tracts, showing the influence of the tumor microenvironment on GBM cell directionality. Also, we found that most GBM cells enter the corpus callosum via a perivascular route. We identified two blood vessel-related mechanisms that allow invasion orthogonal to the myelinated axonal tract direction. We discovered that white matter tract directionality did not change significantly in the early stages of GBM colonization. This might explain limitations of modern clinical imaging to depict white matter glioma infiltration. However, we found that the shape of THG discontinuities differs between GBM cells and other resident cells, which could potentially serve as an imaging biomarker. To summarize, this tailored three-photon microscopy methodology allows unprecedented intravital investigation of GBM invasion in the gray and white matter, enabling the discovery of novel (sub-)cellular mechanisms in cancer and its microenvironment deep in the brain.

Retro is the new modern: Contemporary application of gold impregnation staining on brain cryosections for digital image analysis

Background and purpose: Since the times of Golgi and Cajal, impregnation with gold or silver has been used to visualize microscopic details of the nervous tissue. Although immunohistochemistry has largely replaced impregnation techniques, they are still used, and there is a growing interest in combining them with modern image analysis methods for quantitative studies in neuroscience. The aim of this research was to modify the gold chloride impregnation method published by Schmued to improve consistency of staining, to be adequate for digital image analysis. Materials and methods: Brains of 8 six-month-old female Wistar rats were fixed in 4% PFA, cryoprotected in sucrose and flash‑frozen in liquid nitrogen. Neighboring sets of coronal sections were chosen for gold impregnation, Nissl staining and MAP2 immunohistochemistry. Whole-slide images and images of specific regions were taken for analysis. Results: Myelinated fibers were stained dark reddish to brown on goldstained sections, and other tissue was yellowish, which gave an excellent contrast for digital image analysis. Gold staining was consistent in all regions, and no major artifacts were noticed. When compared to Nissl and MAP2, only myelinated structures were stained with gold impregnation. Conclusions: Modified gold impregnation method is an alternative that’s on par with traditional myelin staining methods. The new, modified gold impregnation method gives a consistent and reproducible staining suitable for digital image analysis. It can be useful in morphometric evaluation of nervous tissue and investigation of neuropathological changes in nervous tissue, especially for quantitative studies.

Multiscale label-free imaging of myelin in human brain tissue with polarization-sensitive optical coherence tomography and birefringence microscopy.

The combination of polarization-sensitive optical coherence tomography (PS-OCT) and birefringence microscopy (BRM) enables multiscale assessment of myelinated axons in postmortem brain tissue, and these tools are promising for the study of brain connectivity and organization. We demonstrate label-free imaging of myelin structure across the mesoscopic and microscopic spatial scales by performing serial-sectioning PS-OCT of a block of human brain tissue and periodically sampling thin sections for high-resolution imaging with BRM. In co-registered birefringence parameter maps, we observe good correspondence and demonstrate that BRM enables detailed validation of myelin (hence, axonal) organization, thus complementing the volumetric information content of PS-OCT.

Recombinant Erythropoietin Induces Oligodendrocyte Progenitor Cell Proliferation After Traumatic Brain Injury and Delayed Hypoxemia

Traumatic brain injury (TBI) can result in axonal loss and demyelination, leading to persistent damage in the white matter. Demyelinated axons are vulnerable to pathologies related to an abnormal myelin structure that expose neurons to further damage. Oligodendrocyte progenitor cells (OPCs) mediate remyelination after recruitment to the injury site. Often this process is inefficient due to inadequate OPC proliferation. To date, no effective treatments are currently available to stimulate OPC proliferation in TBI. Recombinant human erythropoietin (rhEPO) is a pleiotropic neuroprotective cytokine, and its receptor is present in all stages of oligodendroglial lineage cell differentiation. Therefore, we hypothesized that rhEPO administration would enhance remyelination after TBI through the modulation of OPC response. Utilizing a murine model of controlled cortical impact and a primary OPC culture in vitro model, we characterized the impact of rhEPO on remyelination and proliferation of oligodendrocyte lineage cells. Myelin black gold II staining of the peri-contusional corpus callosum revealed an increase in myelinated area in association with an increase in BrdU-positive oligodendrocytes in injured mice treated with rhEPO. Furthermore, morphological analysis of OPCs showed a decrease in process length in rhEPO-treated animals. RhEPO treatment increased OPC proliferation after in vitro CSPG exposure. Erythropoietin receptor (EPOr) gene knockdown using siRNA prevented rhEPO-induced OPC proliferation, demonstrating that the rhEPO effect on OPC response is EPOr activation dependent. Together, our findings demonstrate that rhEPO administration may promote myelination by increasing oligodendrocyte lineage cell proliferation after TBI.

Electroacupuncture alleviates neuropathic pain caused by SNL by promoting M2 microglia polarization through PD-L1

As a common clinical disease, neuropathic pain is difficult to be cured with drugs. The occurrence and progression of pain is closely related to the response of spinal microglia. Aspartof the regulation of microglialactivity,PD-L1 playsacriticalrole. Loss of PD-L1 promoted the polarization of M1-like microglia. Increased expression of PD-L1 promoted M2-like polarization. Electroacupuncture has a significant analgesic effect in clinical practice, but its specific mechanism remains to be further explored. In this study, we verified the role of PD-L1 in EA analgesia and the underlying molecular mechanism through spinal nerve ligation (SNL) in rats and lipopolysaccharide (LPS)-treated BV2 microglial cells. Forbehavioralstudiesofrats,mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured, and spinal cord neuros were examined under transmission electron microscopyto determine changes to their myelin structure. The expression levels of PD-L1 and M1/M2-specific markers in rat spinal cord and BV2 microglial cells were measured by enzyme-linked immunosorbent assay, flow cytometry, immunofluorescence staining and Western blot analysis. Our study showed that EA increased the pain threshold, reduced the destruction of myelin structure, promoted the expression of PD-L1 and PD-1, inhibited the MAPK signaling pathway, and promoted the conversion of microglial polarization from the M1 phenotype to the M2 phenotype in SNL rats. PD-L1 knockdown reversed these effects of EA. In addition, PD-L1 knockdown activated the MAPK signaling pathway, promoted microglial polarization to the M1 phenotype, decreased the expression of anti-inflammatory mediators and increased the expression of proinflammatory factors in LPS-stimulated BV2 microglial cells. Our results showed that EA may regulate the excitability of primary afferent neurons through PD-L1 and then inhibit the MAPK signaling pathway to promote the transformation of activated M1 microglia into M2 microglia, reduce inflammatory reactions, and finally achieve analgesic effects. A therapy targeting PD-L1 may be an effective strategy for treating neuropathic pain.

Joint capsule innervation does not explain the difference in symptoms between scaphotrapezial and trapeziometacarpal osteoarthritis

ObjectivesPeritrapezial osteoarthritis (OA) includes scaphotrapezial and trapeziometacarpal OA. In clinical practice, scaphotrapezial OA seems better tolerated than trapeziometacarpal OA, with fewer complaints and better tolerance. The difference in pain could be linked to a difference in joint capsule innervation, perhaps with fewer nerve fibers in the scaphotrapezial than the trapeziometacarpal joint. Materials and methodsWe performed a histologic evaluation of these two joints to compare their respective innervation in 17 cadaveric specimens with peritrapezial OA. Radiographic scoring confirmed the presence of peritrapezial OA. Mean Kellgren-Lawrence score was 2.2 ± 1.1 in the trapeziometacarpal joint and 1.5 ± 0.7 in the scaphotrapezial joint (p = 0.08). ResultsThere was no difference between scaphotrapezial and trapeziometacarpal joints in number of neurofilaments: 5.2 ± 3.9 and 4.4 ± 4.5, respectively (p = 0.20). A significant difference was found in S100 staining (myelinated structures), with a higher rate in the scaphotrapezial joint: 11.8 ± 7.5 vs 6.6 ± 5.2 (p = 0.005). ConclusionThe present study suggests that lower tolerance of trapeziometacarpal OA is not due to a difference in joint capsule innervation. On the contrary, we found a higher rate of myelinated tissues in the scaphotrapezial joint. These results suggested other pain pathways to explain clinical observations.

Glycine disrupts myelin, glutamatergic neurotransmission, and redox homeostasis in a neonatal model for non ketotic hyperglycinemia

Non ketotic hyperglycinemia (NKH) is an inborn error of glycine metabolism caused by mutations in the genes encoding glycine cleavage system proteins. Classic NKH has a neonatal onset, and patients present with severe neurodegeneration. Although glycine accumulation has been implicated in NKH pathophysiology, the exact mechanisms underlying the neurological damage and white matter alterations remain unclear. We investigated the effects of glycine in the brain of neonatal rats and MO3.13 oligodendroglial cells. Glycine decreased myelin basic protein (MBP) and myelin-associated glycoprotein (MAG) in the corpus callosum and striatum of rats on post-natal day (PND) 15. Glycine also reduced neuroglycan 2 (NG2) and N-methyl-d-aspartate receptor subunit 1 (NR1) in the cerebral cortex and striatum on PND15. Moreover, glycine reduced striatal glutamate aspartate transporter 1 (GLAST) content and neuronal nucleus (NeuN), and increased glial fibrillary acidic protein (GFAP) on PND15. Glycine also increased DCFH oxidation and malondialdehyde levels and decreased GSH concentrations in the cerebral cortex and striatum on PND6, but not on PND15. Glycine further reduced viability but did not alter DCFH oxidation and GSH levels in MO3.13 cells after 48- and 72-h incubation. These data indicate that impairment of myelin structure and glutamatergic system and induction of oxidative stress are involved in the neuropathophysiology of NKH.

Characterization of membrane-interaction mechanisms of proteins using vacuum-ultraviolet circular dichroism spectroscopy.

Protein-membrane interactions play an important role in various biological phenomena, such as material transport, demyelinating diseases, and antimicrobial activity. We combined vacuum-ultraviolet circular dichroism (VUVCD) spectroscopy with theoretical (e.g., molecular dynamics and neural networks) and polarization experimental (e.g., linear dichroism and fluorescence anisotropy) methods to characterize the membrane interaction mechanisms of three soluble proteins (or peptides). α1 -Acid glycoprotein has the drug-binding ability, but the combination of VUVCD and neural-network method revealed that the membrane interaction causes the extension of helix in the N-terminal region, which reduces the binding ability. Myelin basic protein (MBP) is an essential component of the myelin sheath with a multi-layered structure. Molecular dynamics simulations using a VUVCD-guided system showed that MBP forms two amphiphilic and three non-amphiphilic helices as membrane interaction sites. These multivalent interactions may allow MBP to interact with two opposing membrane leaflets, contributing to the formation of a multi-layered myelin structure. The antimicrobial peptide magainin 2 interacts with the bacterial membrane, causing damage to its structure. VUVCD analysis revealed that the M2 peptides assemble in the membrane and turn into oligomers with a β-strand structure. Linear dichroism and fluorescence anisotropy suggested that the oligomers are inserted into the hydrophobic core of the membrane, disrupting the bacterial membrane. Overall, our findings demonstrate that VUVCD and its combination with theoretical and polarization experimental methods pave the way for unraveling the molecular mechanisms of biological phenomena related to protein-membrane interactions.