Nogo receptor inhibition enhances functional recovery following lysolecithin-induced demyelination in mouse optic chiasm

Deferiprone promoted remyelination and functional recovery through enhancement of oligodendrogenesis in experimental demyelination animal model

Remyelination refers to myelin regeneration, which reestablishes metabolic supports to axons. However, remyelination often fails in multiple sclerosis (MS), leading to chronic demyelination and axonal degeneration. Therefore, pharmacological approaches toward enhanced remyelination are highly demanded. Recently, deferiprone (DFP) was reported to exert neuroprotective effects, besides its iron-chelating ability. Since DFP exerts protective effects through various mechanisms, which share several factors with myelin formation process, we aimed to investigate the effects of DFP treatment on remyelination. Focal demyelination was induced by injection of lysolecithin, into the optic nerve of male C57BL/6J mice. The animals were treated with DFP/vehicle, starting from day 7 and continued during the myelin repair period. Histopathological, electrophysiological, and behavioral studies were used to evaluate the outcomes. Results showed that DFP treatment enhanced remyelination, decreased g-ratio and increased myelin thickness. At the mechanistic level, DFP enhanced oligodendrogenesis and ameliorated gliosis during the remyelination period. Furthermore, our results indicated that enhanced remyelination led to functional recovery as evaluated by the electrophysiological and behavioral tests. Even though the exact molecular mechanisms by which DFP-enhanced myelin repair remain to be elucidated, these results raise the possibility of using deferiprone as a therapeutic agent for remyelination therapy in MS.

Forceps minor control of social behaviour

The PRISM project, funded by the EU's Innovative Medicines Initiative, has identified a transdiagnostic, pathophysiological relationship between the integrity of the default mode network (DMN) and social dysfunction. To explore the causal link between DMN integrity and social behaviour, we employed a preclinical back-translation approach, using focal demyelination of the forceps minor to disrupt DMN connectivity in mice. By applying advanced techniques such as functional ultrasound imaging and automated analysis of social behaviour, we demonstrated that reduced DMN connectivity leads to impaired social interactions and increased anxiety in mice. Notably, these effects were reversible, indicating that the forceps minor, a critical fibre tract connecting key DMN regions in the prefrontal cortex, plays a crucial role in social function. This study provides direct evidence for a causal relationship between DMN integrity and social dysfunction, with potential implications for developing targeted treatments in precision psychiatry.

VEP Latency Delay Reflects Demyelination Beyond the Optic Nerve in the Cuprizone Model

Purpose

Remyelination therapies are advancing for multiple sclerosis, focusing on visual pathways and using visual evoked potentials (VEPs) for de/remyelination processes. While the cuprizone (CZ) model and VEPs are core tools in preclinical trials, many overlook the posterior visual pathway. This study aimed to assess functional and structural changes across the murine visual pathway during de/remyelination.

Methods

One group of C57BL/6 mice underwent a CZ diet for 6 weeks to simulate demyelination, with a subset returning to a regular diet to induce remyelination. An additional group was fed a protracted CZ diet for 12 weeks to maintain chronic demyelination. Visual function was evaluated using electrophysiological recordings, including scotopic threshold responses (STRs) and electroretinograms (ERGs), with VEPs serving as a key biomarker for overall pathway health. Tissues from eyes, brains, and optic nerves (ONs) were collected at different time points for structural analysis.

Results

Our results demonstrated significant effects on VEPs, including increased N1 latencies and reduced amplitudes in the CZ mouse model. However, retinal function remained unaffected, as evidenced by unchanged STRs, ERGs, and retinal ganglion cell counts. Analysis of ONs revealed morphological changes, characterized by a significantly decreased axon diameter in the core region compared to the subpial region. Additionally, there was a significant increase in the g-ratio of the core region at 12 weeks CZ compared to controls. Immunofluorescence further demonstrated a decrease in myelin basic protein levels at 6 and 12 weeks in CZ animals. Interestingly, the dorsal lateral geniculate nucleus and primary visual cortex (V1) exhibited similar myelin changes, correlating with VEP latency alterations.

Conclusions

These data reveal that interpreting VEP latency solely as a marker for ON demyelination is incomplete. Previous preclinical studies have overlooked the posterior visual pathways, necessitating a broader interpretation of VEP latency to cover the entire visual pathway.

Arbutin intervention ameliorates memory impairment in a rat model of lysolecethin induced demyelination: Neuroprotective and anti-inflammatory effects

Cognitive impairment (CI) and memory deficit are prevalent manifestations of multiple sclerosis (MS). This study explores the therapeutic potential of arbutin on memory deficits using a rat hippocampal demyelination model induced by lysophosphatidylcholine (LPC). Demyelination was induced by bilateral injection of 1% LPC into the CA1 area of the hippocampus, and the treated group received daily arbutin injections (50 mg/kg, i.p) for two weeks. Arbutin significantly improved memory impairment 14 days post-demyelination as assessed by Morris water maze test. Histological and immunohistochemical analyses demonstrated that arbutin reduced demyelination suppressed pro-inflammatory markers (IL-1β, TNF-α) and increased anti-inflammatory cytokine IL-10. Arbutin also diminished astrocyte activation, decreased iNOS, enhanced anti-oxidative factors (Nrf2, HO-1), and exhibited neuroprotective effects by elevating myelin markers (MBP) and brain derived neurotrophic factor (BDNF). These findings propose arbutin as a potential therapeutic candidate for multiple sclerosis-associated memory deficits, warranting further clinical exploration.

Neural cell membrane-coated DNA nanogels as a potential target-specific drug delivery tool for the central nervous system

A major bottleneck in drug/gene delivery to enhance tissue regeneration after injuries is to achieve targeted delivery to the cells of interest. Unfortunately, we have not been able to attain effective targeted drug delivery in tissues due to the lack of efficient delivery platforms. Since specific cell-cell interactions exist to impart the unique structure and functionality of tissues and organs, we hypothesize that such specific cellular interactions may also be harnessed for drug delivery applications in the form of cell membrane coatings. Here, we employed neural cell-derived membrane coating technique on DNA nanogels to improve target specificity. The efficacy of neural cell membrane-coated DNA nanogels (NCM-nanogels) was demonstrated by using four types of cell membranes derived from the central nervous system (CNS), namely, astrocytes, microglia, cortical neurons, and oligodendrocyte progenitor cells (OPCs). A successful coating of NCMs over DNA nanogels was confirmed by dynamic light scattering, zeta potential measurements and transmission electron microscopy. Subsequently, an overall improvement in cellular uptake of NCM-nanogels over uncoated DNA nanogels (p < 0.005) was seen. Additionally, we observed a selective uptake of OPC membrane-coated DNA nanogels (NCM-O mem) by oligodendrocytes over other cell types both in vitro and in vivo. Our quantitative polymerase chain reaction (qPCR) results also showed selective and effective gene knockdown capacity of NCM-O mem for OPC transfection. The findings in this work may be beneficial for future drug delivery applications targeted at the CNS.

Magnetization transfer ratio for assessing remyelination after transcranial ultrasound stimulation in the lysolecithin rat model of multiple sclerosis

It has been shown that transcranial ultrasound stimulation (TUS) is capable of attenuating myelin loss and providing neuroprotection in animal models of brain disorders. In this study, we investigated the ability of TUS to promote remyelination in the lysolecithin (LPC)-induced local demyelination in the hippocampus. Demyelination was induced by the micro-injection of 1.5 μL LPC (1%) into the rat hippocampus and the treated group received daily TUS for 5 or 12 days. Magnetic resonance imaging techniques, including magnetization transfer ratio (MTR) and T2-weighted imaging, were used to longitudinally characterize the demyelination model. Furthermore, the therapeutic effects of TUS on LPC-induced demyelination were assessed by Luxol fast blue (LFB) staining. Our data revealed that reductions in MTR values observed during demyelination recover almost completely upon remyelination. The MTR values in demyelinated lesions were significantly higher in TUS-treated rats than in the LPC-only group after undergoing TUS. Form histological observation, TUS significantly reduced the size of demyelinated lesion 7 days after LPC administration. This study demonstrated that MTR was a sensitive and reproducible quantitative marker to assess remyelination process in vivo during TUS treatment. These findings might open new promising treatment strategies for demyelinating diseases such as multiple sclerosis.

Peptide mediated targeted delivery of gold nanoparticles into the demyelination site ameliorates myelin impairment and gliosis

Drug development for multiple sclerosis (MS) clinical management focuses on both neuroprotection and repair strategies, and is challenging due to low permeability of the blood-brain barrier, off-target distribution, and the need for high doses of drugs. The changes in the extracellular matrix have been documented in MS patients. It has been shown that the expression of nidogen-1 increases in MS lesions. Laminin forms a stable complex with nidogen-1 through a heptapeptide which was selected to target the lesion area in this study. Here we showed that the peptide binding was specific to the injured area following lysophosphatidylcholine (LPC) induced demyelination. In vivo data showed enhanced delivery of the peptide-functionalized gold nanoparticles (Pep-GNPs) to the lesion area. In addition, Pep-GNPs administration significantly enhanced myelin content and reduced astrocyte/microglia activation. Results demonstrated the possibility of using this peptide to target and treat lesions in patients suffering from MS.

Cis-p-tau plays crucial role in lysolecithin-induced demyelination and subsequent axonopathy in mouse optic chiasm

Multiple sclerosis (MS) is an autoimmune demyelinating disease that leads to axon degeneration as the major cause of everlasting neurological disability. The cis-phosphorylated tau (cis-p-tau) is an isoform of tau phosphorylated on threonine 231 and causes tau fails to bind micro-tubules and promotes assembly. It gains toxic function and forms tangles in the cell which finally leads to cell death. An antibody raised against cis- p-tau (cis mAb) detects this isoform and induces its clearance. Here, we investigated the formation of cis-p-tau in a lysophosphatidylcholine (LPC)-induced prolonged demyelination model as well as the beneficial effects of its clearance using cis mAb. Cis -p-tau was increased in the lesion site, especially in axons and microglia. Behavioral and functional studies were performed using visual cliff test, visual placing test, and visual evoked potential recording. Cis-p-tau clearance resulted in decreased gliosis, protected myelin and reduced axon degeneration. Analysis of behavioral and electrophysiological data showed that clearance of cis-p-tau by cis mAb treatment improved the visual acuity along with the integrity of the optic pathway. Our results highlight the opportunity of using cis mAb as a new therapy for protecting myelin and axons in patients suffering from MS.

Ultrasound Neuromodulation Reduces Demyelination in a Rat Model of Multiple Sclerosis

Microglia, astrocytes, and oligodendrocyte progenitor cells (OPCs) may serve as targets for remyelination-enhancing therapy. Low-intensity pulsed ultrasound (LIPUS) has been demonstrated to ameliorate myelin loss and inhibit neuroinflammation in animal models of brain disorders; however, the underlying mechanisms through which LIPUS stimulates remyelination and glial activation are not well-understood. This study explored the impacts of LIPUS on remyelination and resident cells following lysolecithin (LPC)-induced local demyelination in the hippocampus. Demyelination was induced by the micro-injection of 1.5 μL of 1% LPC into the rat hippocampus, and the treatment groups received daily LIPUS stimulation for 5 days. The therapeutic effects of LIPUS on LPC-induced demyelination were assessed through immunohistochemistry staining. The staining was performed to evaluate remyelination and Iba-1 staining as a microglia marker. Our data revealed that LIPUS significantly increased myelin basic protein (MBP) expression. Moreover, the IHC results showed that LIPUS significantly inhibited glial cell activation, enhanced mature oligodendrocyte density, and promoted brain-derived neurotrophic factor (BDNF) expression at the lesion site. In addition, a heterologous population of microglia with various morphologies can be found in the demyelination lesion after LIPUS treatment. These data show that LIPUS stimulation may serve as a potential treatment for accelerating remyelination through the attenuation of glial activation and the enhancement of mature oligodendrocyte density and BDNF production.

Current status of neuroprotective and neuroregenerative strategies in multiple sclerosis: A systematic review

BACKGROUND

Immune-mediated demyelination and consequent degeneration of oligodendrocytes and axons are hallmark features of multiple sclerosis (MS). Remyelination declines in progressive MS, causing permanent axonal loss and irreversible disabilities. Strategies aimed at enhancing remyelination are critical to attenuate disease progression.

OBJECTIVE

We systematically reviewed recent advances in neuroprotective and regenerative therapies for MS, covering preclinical and clinical studies.

METHODS

We searched three biomedical databases using defined keywords. Two authors independently reviewed articles for inclusion based on pre-specified criteria. The data were extracted from each study and assessed for risk of bias.

RESULTS

Our search identified 7351 studies from 2014 to 2020, of which 221 met the defined criteria. These studies reported 262 interventions, wherein 92% were evaluated in animal models. These interventions comprised protein, RNA, lipid and cellular biologics, small molecules, inorganic compounds, and dietary and physiological interventions. Small molecules were the most highly represented strategy, followed by antibody therapies and stem cell transplantation.

CONCLUSION

While significant strides have been made to develop regenerative treatments for MS, the current evidence illustrates a skewed representation of the types of strategies that advance to clinical trials. Further examination is thus required to address current barriers to implementing experimental treatments in clinical settings.

The Cross Talk between Underlying Mechanisms of Multiple Sclerosis and Epilepsy May Provide New Insights for More Efficient Therapies

Despite the significant differences in pathological background of neurodegenerative diseases, epileptic seizures are a comorbidity in many disorders such as Huntington disease (HD), Alzheimer's disease (AD), and multiple sclerosis (MS). Regarding the last one, specifically, it has been shown that the risk of developing epilepsy is three to six times higher in patients with MS compared to the general population. In this context, understanding the pathological processes underlying this connection will allow for the targeting of the common and shared pathological pathways involved in both conditions, which may provide a new avenue in the management of neurological disorders. This review provides an outlook of what is known so far about the bidirectional association between epilepsy and MS.

Piperine Improves Experimental Autoimmune Encephalomyelitis (EAE) in Lewis Rats Through its Neuroprotective, Anti-inflammatory, and Antioxidant Effects

Inflammation, demyelination, glial activation, and oxidative damage are the most pathological hallmarks of multiple sclerosis (MS). Piperine, a main bioactive alkaloid of black pepper, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has been less studied in the experimental autoimmune encephalomyelitis (EAE) models. In this study, the efficiency of piperine on progression of EAE model and myelin repair mechanisms was investigated. EAE was induced in female Lewis rats and piperine and its vehicle were daily administrated intraperitoneally from day 8 to 29 post immunization. We found that piperine alleviated neurological deficits and EAE disease progression. Luxol fast blue and H&E staining and immunostaining of lumbar spinal cord cross sections confirmed that piperine significantly reduced the extent of demyelination, inflammation, immune cell infiltration, microglia, and astrocyte activation. Gene expression analysis in lumbar spinal cord showed that piperine treatment decreased the level of pro-inflammatory cytokines (TNF-α, IL-1β) and iNOS and enhanced IL-10, Nrf2, HO-1, and MBP expressions. Piperine supplementation also enhanced the total antioxidant capacity (FRAP) and reduced the level of oxidative stress marker (MDA) in the CNS of EAE rats. Finally, we found that piperine has anti-apoptotic and neuroprotective effect in EAE through reducing caspase-3 (apoptosis marker) and enhancing BDNF and NeuN expressing cells. This study strongly indicates that piperine has a beneficial effect on the EAE progression and could be considered as a potential therapeutic target for MS treatment. Upcoming clinical trials will provide a deeper understanding of piperine's role for the treatment of the MS.

Modulation of Nogo receptor 1 expression orchestrates myelin-associated infiltration of glioblastoma

As the clinical failure of glioblastoma treatment is attributed by multiple components, including myelin-associated infiltration, assessment of the molecular mechanisms underlying such process and identification of the infiltrating cells have been the primary objectives in glioblastoma research. Here, we adopted radiogenomic analysis to screen for functionally relevant genes that orchestrate the process of glioma cell infiltration through myelin and promote glioblastoma aggressiveness. The receptor of the Nogo ligand (NgR1) was selected as the top candidate through Differentially Expressed Genes (DEG) and Gene Ontology (GO) enrichment analysis. Gain and loss of function studies on NgR1 elucidated its underlying molecular importance in suppressing myelin-associated infiltration in vitro and in vivo. The migratory ability of glioblastoma cells on myelin is reversibly modulated by NgR1 during differentiation and dedifferentiation process through deubiquitinating activity of USP1, which inhibits the degradation of ID1 to downregulate NgR1 expression. Furthermore, pimozide, a well-known antipsychotic drug, upregulates NgR1 by post-translational targeting of USP1, which sensitizes glioma stem cells to myelin inhibition and suppresses myelin-associated infiltration in vivo. In primary human glioblastoma, downregulation of NgR1 expression is associated with highly infiltrative characteristics and poor survival. Together, our findings reveal that loss of NgR1 drives myelin-associated infiltration of glioblastoma and suggest that novel therapeutic strategies aimed at reactivating expression of NgR1 will improve the clinical outcome of glioblastoma patients.

Metformin Protects Myelin from Degeneration in A Mouse Model of Iysophosphatidylcholine-Induced Demyelination in The Optic Chiasm

Objective

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system. The autoimmune pathology and long-term inflammation lead to substantial demyelination. These events lead to a substantial loss of oligodendrocytes (OLs), which in a longer period, results in axonal loss and long-term disabilities. Neural cells protection approaches decelerate or inhibit the disease progress to avoid further disability. Previous studies showed that metformin has beneficial effects against neurodegenerative conditions. In this experimental study, we examined possible protective effects of metformin on toxin-induced myelin destruction in adult mice brains.

Materials and Methods

Lysophosphatidylcholine (LPC) was used to induce demyelination in mice optic chiasm. We examined the extent of demyelination at different time points post LPC injection using myelin staining and evaluated the severity of inflammation. Functional state of optic pathway was evaluated by visual evoked potential (VEP) recording.

Results

Metformin attenuated LPC-induced demyelination (P<0.05) and inflammation (P<0.05) and protected against significant decrease (P<0.05) in functional conductivity of optic tract. These data indicated that metformin administration attenuates the myelin degeneration following LPC injection which led to functional enhancement.

Conclusion

Our findings suggest metformin for combination therapy for patients suffering from the myelin degenerative diseases, especially multiple sclerosis; however, additional mechanistic studies are required.

An optimized animal model of lysolecithin induced demyelination in optic nerve; more feasible, more reproducible, promising for studying the progressive forms of multiple sclerosis

BACKGROUND

Multiple Sclerosis (MS) is a demyelinating disease leading to long-term neurological deficit due to unsuccessful remyelination and axonal loss. Currently, there are no satisfactory treatments for progressive MS somewhat due to the lack of an adequate animal model for studying the mechanisms of disease progression and screening new drugs.

NEW METHOD

Lysolecithin (LPC) or agarose-gel loaded LPC (AL-LPC) were applied to mouse optic nerve behind the globe via a minor surgery. Agarose loading was used to achieve longer time of LPC exposure and subsequently long-lasting demyelination.

RESULTS

The lesion sites characterized by luxol fast blue (LFB), FluoroMyelin, Bielschowsky's staining, and immunostaining showed extensive demyelination and axonal damage. The loss of Retinal ganglion cells (RGCs) in the corresponding retinal layer was shown by immunostaining and H&E staining. Visual evoked potential (VEP) recordings showed a significant increase in the latency of the P1 wave and a decrease in the amplitude of the P1N1 wave.

COMPARISON WITH EXISTING METHODS

The new approach with a very minor surgery seems to be more feasible and reproducible compared to stereotaxic LPC injection to optic chiasm. Our data revealed prolonged demyelination, axonal degeneration and RGCs loss in both AL-LPC and LPC groups; however, these pathologies were more extensive in the AL-LPC group.

CONCLUSION

The optimized model provides a longer demyelination time frame and axonal damage followed by RGC degeneration; which is of exceptional interest in investigating axonal degeneration mechanisms and screening the new drugs for progressive MS.

Arbutin Improves Functional Recovery and Attenuates Glial Activation in Lysolecethin-Induced Demyelination Model in Rat Optic Chiasm

Neuroinflammation, glial activation, and oxidative injury are the main pathological mechanisms of demyelination in multiple sclerosis (MS). Arbutin, a natural polyphenol compound, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has not been studied in the experimental animal models of MS. In the present study, the efficiency of arbutin on lysolecthin (LPC)-induced local demyelination model was investigated. Demyelination was induced by micro-injection of 2 μl LPC (1%) into the rat optic chiasm and the treated group received daily injection of arbutin (50 mg/kg, i.p) during 2 weeks. Visual-evoked potential (VEP) recordings were used to functionally assess the visual pathway. Gene expression analysis was done to evaluate the arbutin effect on the inflammatory, stress oxidative-related mediators, and myelin markers. The myelin-specific staining was performed to assess demyelination and GFAP staining as an astrocyte marker. We found that arbutin significantly reduced P1-latency of VEPs waves and demyelination at 7 and 14 days post-demyelination. Arbutin decreased inflammatory cytokines (IL-1B, IL-17, TNF-α) and iNOS mRNA expression level. In addition, the expression level of anti-inflammatory cytokine (IL-10) and antioxidant mediators (Nrf-2 and HO-1) was enhanced by arbutin treatment. Arbutin increased MBP and Olig2 expression levels in demyelination context. Finally, arbutin attenuated GFAP as an astrocyte marker. Finally, this study demonstrates that arbutin improves functional recovery and myelin repair in the demyelinated optic chiasm through attenuation of inflammation, astrocyte activation, and oxidative stress. These findings might open new promising avenues for treating demyelinating disorders such as multiple sclerosis. Graphical abstract.

Piperine ameliorated memory impairment and myelin damage in lysolecethin induced hippocampal demyelination

AIMS

We still do not have effective treatment for hippocampal demyelination and memory deficit, the two common comorbidities in multiple sclerosis (MS). This study aimed to assess the therapeutic effect of Piperine (the main alkaloid of black pepper) in an experimental model of demyelination.

MAIN METHODS

Demyelination was induced in male Wistar rats by bilateral injection of lysolecithin (LPC) into the CA1 region of the hippocampus. Piperine (5, 10, 20 mg/kg) was daily injected intraperitoneally three days post LPC injection for ten days. The spatial memory was examined by the Morris water maze task. Demyelination and astrocyte activation were assessed by an immunohistological study. The gene expression analysis of TNF-α, IL1-β, NF-κB, IL-10, Foxp3, iNOS, Nrf2, HO1, MBP, and BDNF was done using qPCR. The total antioxidant capacity of hippocampal tissue was measured using FRAP assay.

KEY FINDINGS

Our results showed that piperine improved the memory performance and myelin repair in the hippocampal demyelination model. Piperine inhibited iNOS expression concomitant with enhanced expression levels of Nrf2, HO1 and the total antioxidant capacity in the hippocampal tissue. Piperine treatment significantly reduced the gene expression level of TNF-α, IL1-β, NF-κB, and glial activation in the injured area; however, the mRNA level of IL-10, Foxp3, BDNF and MBP were significantly increased.

SIGNIFICANCE

We found piperine to be an effective treatment for spatial memory impairment and myelin repair in the hippocampal demyelination model. However, further experimental evidence is needed to investigate the precise mechanisms underlying piperine as a promising therapeutic target in MS patients.

Enhancing myelin repair in experimental model of multiple sclerosis using immobilized chondroitinase ABC I on porous silicon nanoparticles

Removal of chondroitin sulfate proteoglycans (CSPGs) with chondroitinase ABC I (ChABC) facilitates axonal plasticity, axonal regeneration and remyelination, following injury to the central nervous system (CNS). However, the ChABC rapidly undergoes thermal inactivity and needs to be injected repeatedly. Here this limitation was overcame by immobilizing the ChABC on porous silicon (PSi) nanoparticles (ChABC@PSi). The efficacy of immobilized ChABC on CSPGs level and the demyelination insult was assessed in mice corpora callosa demyelinated by 6 weeks cuprizone (CPZ) feeding. ChABC@PSi was able to reduce the amount of CSPGs two weeks after animals treatment. CSPGs digestion by ChABC@PSi reduced the extent of demyelinated area as well as the astrogliosis. Furthermore, ChABC@PSi treatment increased the number of newly generated oligodendrocyte lineage cells which imply for enhanced myelin repair. Our results showed that effective CSPGs digestion by ChABC@PSi enhanced remyelination in CPZ model. Accordingly, ChABC@PSi may have a great potential to be used for treatment of diseases like multiple sclerosis and spinal cord injury by promoting the regeneration of damaged nerves.

Fasudil alleviates brain damage in rats after carbon monoxide poisoning through regulating neurite outgrowth inhibitor/oligodendrocytemyelin glycoprotein signalling pathway

Carbon monoxide (CO) poisoning can lead to many serious neurological symptoms. Currently, there are no effective therapies for CO poisoning. In this study, rats exposed to CO received hyperbaric oxygen therapy, and those in the Fasudil group were given additional Fasudil injection once daily. We found that the escape latency in CO poisoning group (CO group) was significantly prolonged, the T₁ /T_total was obviously decreased, and the mean escape time and the active escape latency were notably extended compared with those in normal control group (NC group, P < 0.05). After administration of Fasudil, the escape latency was significantly shortened, T₁ /T_total was gradually increased as compared with CO group (>1 week, P < 0.05). Ultrastructural damage of neurons and blood-brain barrier of rats was serious in CO group, while the structural and functional integrity of neuron and mitochondria maintained relatively well in Fasudil group. Moreover, we also noted that the expressions of neurite outgrowth inhibitor (Nogo), oligodendrocyte-myelin glycoprotein (OMgp) and Rock in brain tissue were significantly increased in CO group, and the elevated levels of the three proteins were still observed at 2 months after CO poisoning. Fasudil markedly reduced their expressions compared with those of CO group (P < 0.05). In summary, the activation of Nogo-OMgp/Rho signalling pathway is associated with brain injury in rats with CO poisoning. Fasudil can efficiently down-regulate the expressions of Nogo, OMgp and Rock proteins, paving a way for the treatment of acute brain damage after CO poisoning.

Impairment of frequency-specific responses associated with altered electrical activity patterns in auditory thalamus following focal and general demyelination

Multiple sclerosis is characterized by intermingled episodes of de- and remyelination and the occurrence of white- and grey-matter damage. To mimic the randomly distributed pathophysiological brain lesions observed in MS, we assessed the impact of focal white and grey matter demyelination on thalamic function by directing targeted lysolecithin-induced lesions to the capsula interna (CI), the auditory cortex (A1), or the ventral medial geniculate nucleus (vMGN) in mice. Pathophysiological consequences were compared with those of cuprizone treatment at different stages of demyelination and remyelination. Combining single unit recordings and auditory stimulation in freely behaving mice revealed changes in auditory response profile and electrical activity pattern in the thalamus, depending on the region of the initial insult and the state of remyelination. Cuprizone-induced general demyelination significantly diminished vMGN neuronal activity and frequency-specific responses. Targeted lysolecithin-induced lesions directed either to A1 or to vMGN revealed a permanent impairment of frequency-specific responses, an increase in latency of auditory responses and a reduction in occurrence of burst firing in vMGN neurons. These findings indicate that demyelination of grey matter areas in the thalamocortical system permanently affects vMGN frequency specificity and the prevalence of bursting in the auditory thalamus.

Curcumin-loaded nanoparticles ameliorate glial activation and improve myelin repair in lyolecithin-induced focal demyelination model of rat corpus callosum

Curcumin has been introduced as effective anti-inflammatory agent in treatment of several inflammatory disorders. Despite the wide range pharmacological activities, clinical application of curcumin is restricted mainly due to the low water solubility of this substance. More recently, we could remarkably improve the aqueous solubility of curcumin by its encapsulation in chitosan-alginate-sodium tripolyphosphate nanoparticles (CS-ALG-STPP NPs). In this study, the anti-inflammatory and myelin protective effects of curcumin-loaded NPs were evaluated in lysolecithin (LPC)-induced focal demyelination model. Pharmacokinetic of curcumin was assessed using high performance liquid chromatography (HPLC). Local demyelination was induced by injection of LPC into corpus callosum of rats. Animals were pre-treated with intraperitoneal (i.p.) injections of curcumin or curcumin-loaded NPs at dose of 12.5 mg/kg, 10 days prior to LPC injection and the injections were continued for 7 or 14 days post lesion. Hematoxylin and eosin (H&E) staining and immunostaining against activated glial cells including astrocytes and microglia were carried out for assessment of inflammation level in lesion site. Myelin specific staining was performed to evaluate the effect of curcumin-loaded NPs on myelination of LPC receiving animals. HPLC results showed the higher plasma concentration of curcumin after administration of NPs. Histological evaluation demonstrated that, the extent of demyelination areas was reduced in animals under treatment of curcumin-loaded NPs. Furthermore, treatment with curcumin-loaded NPs effectively attenuated glial activation and inflammation in LPC-induced demyelination model compared to curcumin receiving animals. Overall; these findings indicate that treatment with curcumin-loaded NPs preserve myelinated axons through amelioration of glial activation and inflammation in demyelination context.

p75NTR and TROY: Uncharted Roles of Nogo Receptor Complex in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), have been on the forefront of drug discovery for most of the myelin inhibitory molecules implicated in axonal regenerative process. Nogo-A along with its putative receptor NgR and co-receptor LINGO-1 has paved the way for the production of pharmaceutical agents such as monoclonal antibodies, which are already put into handful of clinical trials. On the other side, little progress has been made towards clarifying the role of neurotrophin receptor p75 (p75NTR) and TROY in disease progression, other key players of the Nogo receptor complex. Previous work of our lab has shown that their exact location and type of expression is harmonized in a phase-dependent manner. Here, in this review, we outline their façade in normal and diseased central nervous system (CNS) and suggest a role for p75NTR in chronic axonal regeneration whereas TROY in acute inflammation of EAE intercourse.

Baseline effects of lysophosphatidylcholine and nerve growth factor in a rat model of sciatic nerve regeneration after crush injury

Schwann cells play a major role in helping heal injured nerves. They help clear debris, produce neurotrophins, upregulate neurotrophin receptors, and form bands of Büngner to guide the healing nerve. But nerves do not always produce enough neurotrophins and neurotrophin receptors to repair themselves. Nerve growth factor (NGF) is an important neurotrophin for promoting nerve healing and lysophosphatidylcholine (LPC) has been shown to stimulate NGF receptors (NGFR). This study tested the administration of a single intraneural injection of LPC (1 mg/mL for single LPC injection and 10 mg/mL for multiple LPC injections) at day 0 and one (day 7), two (days 5 and 7), or three (days 5, 7, and 9) injections of NGF (160 ng/mL for single injections and 80 ng/mL for multiple injections) to determine baseline effects on crushed sciatic nerves in rats. The rats were randomly divided into four groups: control, crush, crush-NGF, and crush-LPC-NGF. The healing of the nerves was measured weekly by monitoring gait; electrophysiological parameters: compound muscle action potential (CMAP) amplitudes; and morphological parameters: total fascicle areas, myelinated fiber counts, fiber densities, fiber packing, and mean g-ratio values at weeks 3 and 6. The crush, crush-NGF, and crush-LPC-NGF groups statistically differed from the control group for all six weeks for the electrophysiological parameters but only differed from the control group at week 3 for the morphological parameters. The crush, crush-NGF, and crush-LPC-NGF groups did not differ from each other over the course of the study. Single injections of LPC and NGF one week apart or multiple treatments of NGF at 5, 7 and 9 days post-injury did not alter the healing rate of the sciatic nerves during weeks 1-6 of the study. These findings are important to define the baseline effects of NGF and LPC injections, as part of a larger effort to determine the minimal dose regimen of NGF to regenerate peripheral nerves.

Attempts to Overcome Remyelination Failure: Toward Opening New Therapeutic Avenues for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic immune-mediated disorder of the central nervous system that results in destruction of the myelin sheath wrapped around the axons and eventual axon degeneration. The disease is pathologically heterogeneous; however, perhaps its most frustrating aspect is the lack of efficient regenerative response for remyelination. Current treatment strategies are based on anti-inflammatory or immunomodulatory medications that have the potential to reduce the numbers of newly evolving lesions. However, therapies are still required that can repair already damaged myelin for which current treatments are not effective. A prerequisite for the development of such new treatments is understanding the reasons for insufficient endogenous repair. This review briefly summarizes the currently suggested causes of remyelination failure in MS and possible solutions.

Nogo-A antibodies enhance axonal repair and remyelination in neuro-inflammatory and demyelinating pathology

Two hallmarks of chronic multiple sclerosis lesions are the absence of significant spontaneous remyelination and primary as well as secondary neurodegeneration. Both characteristics may be influenced by the presence of inhibitory factors preventing myelin and neuronal repair. We investigated the potential of antibodies against Nogo-A, a well-known inhibitory protein for neuronal growth and plasticity, to enhance neuronal regeneration and remyelination in two animal models of multiple sclerosis. We induced a targeted experimental autoimmune encephalomyelitis (EAE) lesion in the dorsal funiculus of the cervical spinal cord of adult rats resulting in a large drop of skilled forelimb motor functions. We subsequently observed improved recovery of forelimb function after anti-Nogo-A treatment. Anterograde tracing of the corticospinal tract revealed enhanced axonal sprouting and arborisation within the spinal cord gray matter preferentially targeting pre-motor and motor spinal cord laminae on lesion level and above in the anti-Nogo-A-treated animals. An important additional effect of Nogo-A-neutralization was enhanced remyelination observed after lysolecithin-induced demyelination of spinal tracts. Whereas remyelinated fiber numbers in the lesion site were increased several fold, no effect of Nogo-A-inhibition was observed on oligodendrocyte precursor proliferation, migration, or differentiation. Enhancing remyelination and promoting axonal regeneration and plasticity represent important unmet medical needs in multiple sclerosis. Anti-Nogo-A antibodies hold promise as a potential new therapy for multiple sclerosis, in particular during the chronic phase of the disease when neurodegeneration and remyelination failure determine disability evolution.

Inhibition of GABA A receptor improved spatial memory impairment in the local model of demyelination in rat hippocampus

Cognitive impairment and memory deficit are common features in multiple Sclerosis patients. The mechanism of memory impairment in MS is unknown, but neuroimaging studies suggest that hippocampal demyelination is involved. Here, we investigate the role of GABA A receptor on spatial memory in the local model of hippocampal demyelination. Demyelination was induced in male Wistar rats by bilaterally injection of lysophosphatidylcholine (LPC) 1% into the CA1 region of the hippocampus. The treatment groups were received daily intraventricular injection of bicuculline (0.025, 0.05μg/2μl/animal) or muscimol (0.1, 0.2μg/2μl/animal) 5days after LPC injection. Morris Water Maze was used to evaluate learning and memory in rats. We used Luxol fast blue staining and qPCR to assess demyelination extention and MBP expression level respectively. Immunohistochemistry (IHC) for CD45 and H&E staining were performed to assess inflammatory cells infiltration. Behavioral study revealed that LPC injection in the hippocampus impaired learning and memory function. Animals treated with both doses of bicuculline improved spatial learning and memory function; however, muscimol treatment had no effect. Histological and MBP expression studies confirmed that demylination in LPC group was maximal. Bicuculline treatment significantly reduced demyelination extension and increased the level of MBP expression. H&E and IHC results showed that bicuculline reduced inflammatory cell infiltration in the lesion site. Bicuculline improved learning and memory and decreased demyelination extention in the LPC-induced hippocampal demyelination model. We conclude that disruption of GABAergic homeostasis in hippocampal demyelination context may be involved in memory impairment with the implications for both pathophysiology and therapy.

RNAi targeting Nogo Receptor enhanced survival and proliferation of murine retinal ganglion cells during N-methyl-D-aspartate-induced optic nerve crush

We investigated the effects of lentivirus-mediated RNAi targeting of Nogo Receptor (NgR) on the proliferation and survival of murine retinal ganglion cells (mRGCs) in vitro and in vivo. Cultured mRGCs and C57BL/6 male mice were divided into 4 experimental groups: blank, model [100 μM N-methyl-D-aspartate (NMDA)], nscRNA (100 μM NMDA+ nscRNA vectors) and siNgR (100 μM NMDA+ siNgR vectors). CCK-8 and flow cytometry analyses revealed that silencing NgR enhanced proliferation, cell cycling and survival of NMDA-treated mRGCs. H&E staining showed that NgR silencing enhanced mRGC cell density and reduced angiogenesis in NMDA-treated retinal tissues. TUNEL assays showed that mRGC apoptosis was significantly diminished by NgR silencing in NMDA-treated retinal tissues. Western blotting and qRT-PCR analysis in NMDA-treated mRGCs and murine retinal tissues revealed that NgR silencing resulted in downregulation of RhoA signaling (RhoA and ROCK2). Western blotting showed that levels of activated Bax and cleaved caspase 3 were decreased, while Bcl-2 and pro-caspase 3 were increased in NMDA-treated mRGCs and murine retinal tissues, which corroborated the decreased apoptosis. These findings indicate that NgR gene silencing increases proliferation and survival of mRGCs in NMDA-treated murine retinas, which suggests a potential for therapeutic application to preventing optic nerve damage.

Safety and efficacy of opicinumab in acute optic neuritis (RENEW): a randomised, placebo-controlled, phase 2 trial

BACKGROUND

The human monoclonal antibody opicinumab (BIIB033, anti-LINGO-1) has shown remyelinating activity in preclinical studies. We therefore assessed the safety and tolerability, and efficacy of opicinumab given soon after a first acute optic neuritis episode.

METHODS

This randomised, double-blind, placebo-controlled, phase 2 study (RENEW) was done at 33 sites in Australia, Canada, and Europe in participants (aged 18-55 years) with a first unilateral acute optic neuritis episode within 28 days from study baseline. After treatment with high-dose methylprednisolone (1 g/day, intravenously, for 3-5 days), participants were assigned with a computer-generated sequence with permuted block randomisation (1:1) using a centralised interactive voice and web response system to receive 100 mg/kg opicinumab intravenously or placebo once every 4 weeks (six doses) and followed up to week 32. All study participants and all study staff, including the central readers, were masked to treatment assignment apart from the pharmacist responsible for preparing the study treatments and the pharmacy monitor at each site. The primary endpoint was remyelination at 24 weeks, measured as recovery of affected optic nerve conduction latency using full-field visual evoked potential (FF-VEP) versus the unaffected fellow eye at baseline. Analysis was by intention-to-treat (ITT); prespecified per-protocol (PP) analyses were also done. This study is registered with ClinicalTrials.gov, number NCT01721161.

FINDINGS

The study was done between Dec 21, 2012, and Oct 21, 2014. 82 participants were enrolled, and 41 in each group comprised the ITT population; 33 participants received opicinumab and 36 received placebo in the PP population. Adjusted mean treatment difference of opicinumab versus placebo was -3·5 ms (17·3 vs 20·8 [95% CI -10·6 to 3·7]; 17%; p=0·33) in the ITT population, and -7·6 ms in the PP population (14·7 vs 22·2 [-15·1 to 0·0]; 34%; p=0·050) at week 24 and -6·1 ms (15·1 vs 21·2 [-12·7 to 0·5]; 29%; p=0·071) in the ITT population and -9·1 ms (13·2 vs 22·4 [-16·1 to -2·1]; 41%; p=0·011) in the PP population at week 32. The overall incidence (34 [83%] of 41 in each group) and severity of adverse events (two [5%] of 41 severe adverse events with placebo vs three [7%] of 41 with opicinumab) were similar between groups and no significant effects on brain MRI measures were noted in either group (mean T2 lesion volume change, 0·05 mL [SD 0·21] for placebo vs 0·20 mL [0·52] with opicinumab; 27 [77%] of 35 participants with no change in gadolinium-enhancing [Gd+] lesion number with opicinumab vs 27 [79%] of 34 with placebo; mean 0·4 [SD 0·79 for the placebo group and 0·85 for the opicinumab group] new Gd+ lesions per participant in both groups). Treatment-related serious adverse events were reported in three (7%) of 41 participants in the opicinumab group (hypersensitivity [n=2], asymptomatic increase in transaminase concentrations [n=1]) and none of the participants in the placebo group.

INTERPRETATION

Remyelination did not differ significantly between the opicinumab and placebo groups in the ITT population at week 24. However, results from the prespecified PP population suggest that enhancing remyelination in the human CNS with opicinumab might be possible and warrant further clinical investigation.

FUNDING

Biogen.

The quality of cortical network function recovery depends on localization and degree of axonal demyelination

Myelin loss is a severe pathological hallmark common to a number of neurodegenerative diseases, including multiple sclerosis (MS). Demyelination in the central nervous system appears in the form of lesions affecting both white and gray matter structures. The functional consequences of demyelination on neuronal network and brain function are not well understood. Current therapeutic strategies for ameliorating the course of such diseases usually focus on promoting remyelination, but the effectiveness of these approaches strongly depends on the timing in relation to the disease state. In this study, we sought to characterize the time course of sensory and behavioral alterations induced by de- and remyelination to establish a rational for the use of remyelination strategies. By taking advantage of animal models of general and focal demyelination, we tested the consequences of myelin loss on the functionality of the auditory thalamocortical system: a well-studied neuronal network consisting of both white and gray matter regions. We found that general demyelination was associated with a permanent loss of the tonotopic cortical organization in vivo, and the inability to induce tone-frequency-dependent conditioned behaviors, a status persisting after remyelination. Targeted, focal lysolecithin-induced lesions in the white matter fiber tract, but not in the gray matter regions of cortex, were fully reversible at the morphological, functional and behavioral level. These findings indicate that remyelination of white and gray matter lesions have a different functional regeneration potential, with the white matter being able to regain full functionality while cortical gray matter lesions suffer from permanently altered network function. Therefore therapeutic interventions aiming for remyelination have to consider both region- and time-dependent strategies.

Comparison of RNAi NgR and NEP1-40 in Acting on Axonal Regeneration After Spinal Cord Injury in Rat Models

This study was intended to compare the therapeutic efficacies of NEP1-40 and SiNgR199 on treating spinal cord injury (SCI). Nogo-A, growth associated protein 43 (GAP-43), microtubule associated protein 2 (MAP-2), and amyloid βA4 precursor protein (APP) expressions were determined using western blot and quantitative PCR. Neurite outgrowth detected the growth of neurites, and BDA anterograde tracing was used to label the regenerated axonal. Rats' behavior was assessed with Basso, Beattie, and Bresnahan locomotor rating scale (BBB). Somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) were recorded to evaluate the recovery of the sensory and motor systems. Successful establishment of SCI model was verified by immunocytochemical analysis. The increased expression of APP, as well as the decreased expression of GAP-43 and MAP-2, was observed in the SCI model group, but the trends were reversed after the treatments of NEP1-40, siNgR199, and NEP1-40 + siNgR199. Compared with the SCI group, the average neurite length and the BDA-positive fibers were increased in the NEP1-40, siNgR199, and NEP1-40 + siNgR199 groups. The rats in the siNgR199 group and the NEP1-40 + siNgR199 group both showed significantly higher BBB scores than SCI model group and NEP1-40 group. Suggested by electrophysiological evaluation, both the latency and the amplitude of SEPs as well as MEPs had recovered in the NEP1-40, siNgR199, and NEP1-40 + siNgR199 groups after SCI. Both NEP1-40 and siNgR had repairing effects on SCI, suggesting their role in facilitating axonal regeneration after SCI.

Nogo receptor complex expression dynamics in the inflammatory foci of central nervous system experimental autoimmune demyelination

BACKGROUND

Nogo-A and its putative receptor NgR are considered to be among the inhibitors of axonal regeneration in the CNS. However, few studies so far have addressed the issue of local NgR complex multilateral localization within inflammation in an MS mouse model of autoimmune demyelination.

METHODS

Chronic experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6 mice. Analyses were performed on acute (days 18-22) and chronic (day 50) time points and compared to controls. The temporal and spatial expression of the Nogo receptor complex (NgR and coreceptors) was studied at the spinal cord using epifluorescent and confocal microscopy or real-time PCR. Data are expressed as cells/mm2, as mean % ± SEM, or as arbitrary units of integrated density.

RESULTS

Animals developed a moderate to severe EAE without mortality, followed by a progressive, chronic clinical course. NgR complex spatial expression varied during the main time points of EAE. NgR with coreceptors LINGO-1 and TROY was increased in the spinal cord in the acute phase whereas LINGO-1 and p75 signal seemed to be dominant in the chronic phase, respectively. NgR was detected on gray matter NeuN+ neurons of the spinal cord, within the white matter inflammatory foci (14.2 ± 4.3 % NgR+ inflammatory cells), and found to be colocalized with GAP-43+ axonal growth cones while no β-TubIII+, SMI-32+, or APP+ axons were found as NgR+. Among the NgR+ inflammatory cells, 75.6 ± 9.0 % were microglial/macrophages (lectin+), 49.6 ± 14.2 % expressed CD68 (phagocytic ED1+ cells), and no cells were Mac-3+. Of these macrophages/monocytes, only Arginase-1+/NgR+ but not iNOS+/NgR+ were present in lesions both in acute and chronic phases.

CONCLUSIONS

Our data describe in detail the expression of the Nogo receptor complex within the autoimmune inflammatory foci and suggest a possible immune action for NgR apart from the established inhibitory one on axonal growth. Its expression by inflammatory macrophages/monocytes could signify a possible role of these cells on axonal guidance and clearance of the lesioned area during inflammatory demyelination.

[Neuroprotective effect of Nogo-66 receptor silencing in preterm rats with brain injury caused by intrauterine infection]

OBJECTIVE

To investigate the effect of Nogo-66 receptor (NgR) silencing with specific small interfering RNA (siRNA) on brain injury repair in preterm rats with brain injury caused by intrauterine infection and related mechanism of action.

METHODS

The pregnant Sprague-Dawley rats (with a gestational age of 15 days) were selected, and premature delivery was induced by RU486 or lipopolysaccharide (LPS). The preterm rats delivered by those treated with RU486 were selected as the control group. The preterm rats with brain injury caused by intrauterine infection induced by LPS were divided into model, empty vector, and NgR-siRNA groups, with 36 rats in each group. The rats in the control and model groups were given routine feeding only, and those in the empty vector and NgR-siRNA groups were given an injection of lentiviral empty vector or NgR-siRNA lentivirus via the lateral ventricle on postnatal day 1 (P1) and then fed routinely. On P3, P7, and P14, 8 rats in each group were randomly selected and sacrificed to harvest the brain tissue. RT-PCR was used to measure the mRNA expression of NgR. Western blot was used to to measure the protein expression of active RhoA. The immunofluorescence histochemistry was used to determine the degree of activation of microglial cells and the morphology of oligodendrocyte precursor cells (OPCs). Hematoxylin and eosin staining was used to observe the pathological changes in brain tissue. The behavioral score was evaluated on P30.

RESULTS

On P3, the NgR-siRNA group had significantly lower mRNA expression of NgR and protein expression of active RhoA in brain tissue than the model and empty vector groups (P<0.05). In each group, the mRNA expression of NgR was positively correlated with the protein expression of active RhoA (P<0.05). The results of immunofluorescence histochemistry showed that on P3, the NgR-siRNA group had a significantly reduced fluorescence intensity of the microglial cells labeled with CD11b compared with the model and empty vector groups (P<0.05). The OPCs labeled with O4 antibody in the four groups were mainly presented with tripolar cell morphology. The results of pathological examination showed a normal structure of white matter with clear staining in the periventriclar area in the control group, a loose structure of white matter with disorganized fibers and softening lesions in the model and empty vector groups, and a loose structure of white matter with slightly disorganized fibers, slight gliocyte proliferation, and no significant necrotic lesions in the NgR-siRNA group. As for the behavioral score, compared with the model and empty vector groups, the NgR-siRNA group had a higher score in the suspension test, a longer total activity distance, and greater mean velocity and number of squares crossed, as well as a shorter time of slope test and a shorter time and distance of activity in the central area (P<0.05), while there were no significant differences in these parameters between the NgR-siRNA and control groups (P>0.05).

CONCLUSIONS

NgR silencing with specific siRNA can effectively silence the expression of NgR in pertem rats with brain injury caused by interauterine infection and has a significant neuroprotective effect in brain injury repair.

[Neuroprotective effect of Nogo-66 receptor silencing in preterm rats with brain injury caused by intrauterine infection]

OBJECTIVE

To investigate the effect of Nogo-66 receptor (NgR) silencing with specific small interfering RNA (siRNA) on brain injury repair in preterm rats with brain injury caused by intrauterine infection and related mechanism of action.

METHODS

The pregnant Sprague-Dawley rats (with a gestational age of 15 days) were selected, and premature delivery was induced by RU486 or lipopolysaccharide (LPS). The preterm rats delivered by those treated with RU486 were selected as the control group. The preterm rats with brain injury caused by intrauterine infection induced by LPS were divided into model, empty vector, and NgR-siRNA groups, with 36 rats in each group. The rats in the control and model groups were given routine feeding only, and those in the empty vector and NgR-siRNA groups were given an injection of lentiviral empty vector or NgR-siRNA lentivirus via the lateral ventricle on postnatal day 1 (P1) and then fed routinely. On P3, P7, and P14, 8 rats in each group were randomly selected and sacrificed to harvest the brain tissue. RT-PCR was used to measure the mRNA expression of NgR. Western blot was used to to measure the protein expression of active RhoA. The immunofluorescence histochemistry was used to determine the degree of activation of microglial cells and the morphology of oligodendrocyte precursor cells (OPCs). Hematoxylin and eosin staining was used to observe the pathological changes in brain tissue. The behavioral score was evaluated on P30.

RESULTS

On P3, the NgR-siRNA group had significantly lower mRNA expression of NgR and protein expression of active RhoA in brain tissue than the model and empty vector groups (P<0.05). In each group, the mRNA expression of NgR was positively correlated with the protein expression of active RhoA (P<0.05). The results of immunofluorescence histochemistry showed that on P3, the NgR-siRNA group had a significantly reduced fluorescence intensity of the microglial cells labeled with CD11b compared with the model and empty vector groups (P<0.05). The OPCs labeled with O4 antibody in the four groups were mainly presented with tripolar cell morphology. The results of pathological examination showed a normal structure of white matter with clear staining in the periventriclar area in the control group, a loose structure of white matter with disorganized fibers and softening lesions in the model and empty vector groups, and a loose structure of white matter with slightly disorganized fibers, slight gliocyte proliferation, and no significant necrotic lesions in the NgR-siRNA group. As for the behavioral score, compared with the model and empty vector groups, the NgR-siRNA group had a higher score in the suspension test, a longer total activity distance, and greater mean velocity and number of squares crossed, as well as a shorter time of slope test and a shorter time and distance of activity in the central area (P<0.05), while there were no significant differences in these parameters between the NgR-siRNA and control groups (P>0.05).

CONCLUSIONS

NgR silencing with specific siRNA can effectively silence the expression of NgR in pertem rats with brain injury caused by interauterine infection and has a significant neuroprotective effect in brain injury repair.

Oct4 transcription factor in conjunction with valproic acid accelerates myelin repair in demyelinated optic chiasm in mice

Multiple sclerosis is a demyelinating disease with severe neurological symptoms due to blockage of signal conduction in affected axons. Spontaneous remyelination via endogenous progenitors is limited and eventually fails. Recent reports showed that forced expression of some transcription factors within the brain converted somatic cells to neural progenitors and neuroblasts. Here, we report the effect of valproic acid (VPA) along with forced expression of Oct4 transcription factor on lysolecithin (LPC)-induced experimental demyelination. Mice were gavaged with VPA for one week, and then inducible Oct4 expressing lentiviral particles were injected into the lateral ventricle. After one-week induction of Oct4, LPC was injected into the optic chiasm. Functional remyelination was assessed by visual-evoked potential (VEP) recording. Myelination level was studied using FluoroMyelin staining and immunohistofluorescent (IHF) against proteolipid protein (PLP). IHF was also performed to detect Oct4 and SSEA1 as pluripotency markers and Olig2, Sox10, CNPase and PDGFRα as oligodendrocyte lineage markers. One week after injection of Oct4 expressing vector, pluripotency markers SSEA1 and Oct4 were detected in the rims of the 3rd ventricle. LPC injection caused extensive demyelination and significantly delayed the latency of VEP wave. Animals pre-treated with VPA+Oct4 expressing vector, showed faster recovery in the VEP latency and enhanced myelination. Immunostaining against oligodendrocyte lineage markers showed an increased number of Sox10+ and myelinating cells. Moreover, transdifferentiation of some Oct4-transfected cells (GFP+ cells) to Olig2+ and CNPase+ cells was confirmed by immunostaining. One-week administration of VPA followed by one-week forced expression of Oct4 enhanced myelination by converting transduced cells to myelinating oligodendrocytes. This finding seems promising for enhancing myelin repair within the adult brains.

The axon-glia unit in white matter stroke: mechanisms of damage and recovery

Approximately one quarter of all strokes in humans occur in white matter, and the progressive nature of white matter lesions often results in severe physical and mental disability. Unlike cortical grey matter stroke, the pathology of white matter stroke revolves around disrupted connectivity and injured axons and glial cells, rather than neuronal cell bodies. Consequently, the mechanisms behind ischemic damage to white matter elements, the regenerative responses of glial cells and their signaling pathways, all differ significantly from those in grey matter. Development of effective therapies for white matter stroke would require an enhanced understanding of the complex cellular and molecular interactions within the white matter, leading to the identification of new therapeutic targets. This review will address the unique properties of the axon-glia unit during white matter stroke, describe the challenging process of promoting effective white matter repair, and discuss recently-identified signaling pathways which may hold potential targets for repair in this disease. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.