Demyelination initiated by oligodendrocyte apoptosis through enhancing endoplasmic reticulum-mitochondria interactions and Id2 expression after compressed spinal cord injury in rats

Potential Role of Endoplasmic Reticulum Stress in Modulating Protein Homeostasis in Oligodendrocytes to Improve White Matter Injury in Preterm Infants

Preterm white matter injury (WMI) is a demyelinating disease with high incidence and mortality in premature infants. Oligodendrocyte cells (OLs) are a specialized glial cell that produces myelin proteins and adheres to the axons providing energy and metabolic support which susceptible to endoplasmic reticulum protein quality control. Disruption of cellular protein homeostasis led to OLs dysfunction and cell death, immediately, the unfolded protein response (UPR) activated to attempt to restore the protein homeostasis via IRE1/XBP1s, PERK/eIF2α and ATF6 pathway that reduced protein translation, strengthen protein-folding capacity, and degraded unfolding/misfolded protein. Moreover, recent works have revealed the conspicuousness function of ER signaling pathways in regulating influenced factors such as calcium homeostasis, mitochondrial reactive oxygen generation, and autophagy activation to regulate protein hemostasis and improve the myelination function of OLs. Each of the regulation modes and their corresponding molecular mechanisms provides unique opportunities and distinct perspectives to obtain a deep understanding of different actions of ER stress in maintaining OLs' health and function. Therefore, our review focuses on summarizing the current understanding of ER stress on OLs' protein homeostasis micro-environment in myelination during white matter development, as well as the pathophysiology of WMI, and discussing the further potential experimental therapeutics targeting these factors that restore the function of the UPR in OLs myelination function.

The Emerging Role of Microglial Hv1 as a Target for Immunomodulation in Myelin Repair

In the central nervous system (CNS), the myelin sheath ensures efficient interconnection between neurons and contributes to the regulation of the proper function of neuronal networks. The maintenance of myelin and the well-organized subtle process of myelin plasticity requires cooperation among myelin-forming cells, glial cells, and neural networks. The process of cooperation is fragile, and the balance is highly susceptible to disruption by microenvironment influences. Reactive microglia play a critical and complicated role in the demyelination and remyelination process. Recent studies have shown that the voltage-gated proton channel Hv1 is selectively expressed in microglia in CNS, which regulates intracellular pH and is involved in the production of reactive oxygen species, underlying multifaceted roles in maintaining microglia function. This paper begins by examining the molecular mechanisms of demyelination and emphasizes the crucial role of the microenvironment in demyelination. It focuses specifically on the role of Hv1 in myelin repair and its therapeutic potential in CNS demyelinating diseases.

The role of myelin in neurodegeneration: implications for drug targets and neuroprotection strategies

Myelination of axons in the central nervous system offers numerous advantages, including decreased energy expenditure for signal transmission and enhanced signal speed. The myelin sheaths surrounding an axon consist of a multi-layered membrane that is formed by oligodendrocytes, while specific glycoproteins and lipids play various roles in this formation process. As beneficial as myelin can be, its dysregulation and degeneration can prove detrimental. Inflammation, oxidative stress, and changes in cellular metabolism and the extracellular matrix can lead to demyelination of these axons. These factors are hallmark characteristics of certain demyelinating diseases including multiple sclerosis. The effects of demyelination are also implicated in primary degeneration in diseases such as glaucoma and Alzheimer's disease, as well as in processes of secondary degeneration. This reveals a relationship between myelin and secondary processes of neurodegeneration, including resultant degeneration following traumatic injury and transsynaptic degeneration. The role of myelin in primary and secondary degeneration is also of interest in the exploration of strategies and targets for remyelination, including the use of anti-inflammatory molecules or nanoparticles to deliver drugs. Although the use of these methods in animal models of diseases have shown to be effective in promoting remyelination, very few clinical trials in patients have met primary end points. This may be due to shortcomings or considerations that are not met while designing a clinical trial that targets remyelination. Potential solutions include diversifying disease targets and requiring concomitant interventions to promote rehabilitation.

Ameliorative effect of vitamin E and selenium against bisphenol A-induced toxicity in spinal cord and submandibular salivary glands of adult male albino rats

Bisphenol A (BPA) used in plastic industry. This study evaluate ameliorative effect of vitamin E and selenium in combating BPA toxicity in spinal cord (SC) and submandibular glands (SMGs). Thirty rats divided into three groups [Group I, controls; Group II, BPA orally (25 mg/kg) three times a week, 60 days; Group III, BPA (25 mg/kg) plus vitamin E and selenium in water (1 ml/L/day)]. By histopathological, immunohistochemical, and biochemical investigations. Bisphenol A group showed degenerative alterations. SC gray matter showed pyknotic nuclei and white matter revealed neuropil degeneration. Myelinated fibers showed dispersed myelin. SMGs, exhibited vacuolated cytoplasm in acinar cells. Intense glial fibrillary acidic protein in SC and strong proliferating cell nuclear antigen in acinar and ductal cell nuclei of SMGs. Malondialdehyde elevated in SC and catalase decreased in SMG. Group III, SC and SMG revealed partial recovery. Vitamin E and selenium displayed protective effects against BPA toxicity in SC and SMGs.

Thoracic Jia-Ji electro-acupuncture mitigates low skeletal muscle atrophy and improves motor function recovery following thoracic spinal cord injury in rats

OBJECTIVES

The goal of this study was to determine whether electro-acupuncture (EA) stimulation might protect the motor endplate, minimize muscle atrophy in the hind limbs, and enhance functional recovery of rats with spinal cord injury (SCI).

METHODS

Sprague-Dawley adult female rats (n = 30) were randomly assigned into Sham, SCI, and EA + SCI groups (n = 10 each). Rats in the Sham and SCI groups were bound in prone position only for 30 min, and rats in the EA + SCI group were treated with electro-acupuncture. The EA was conducted from the first day after surgery, lasted for 30 mins, once every day for 28 consecutive days.

RESULTS

EA significantly prevented motor endplate degeneration, improved electrophysiological function, and ameliorated hindlimb muscle atrophy after SCI. Meanwhile, EA upregulated Tuj-1 expression, downregulated GFAP expression, and reduced glial scar formation. Additionally, after 4 weeks of EA treatment, the serum of SCI rats exhibited a reduced inflammatory response.

CONCLUSION

These findings suggest that EA can preserve the motor endplate and reduce muscular atrophy. In addition, EA has been shown to improve the function of upper and lower neurons, reduce glial scar formation, suppress systemic inflammation, and improve axon regeneration.

Honokiol exerts protective effects on neural myelin sheaths after compressed spinal cord injury by inhibiting oligodendrocyte apoptosis through regulation of ER-mitochondrial interactions

OBJECTIVE

To investigate the effect of honokiol on demyelination after compressed spinal cord injury (CSCI) and it's possible mechanism.

DESIGN

Animal experiment study.

SETTING

Institute of Neuroscience of Chongqing Medical University.

INTERVENTIONS

Total of 69 Sprague-Dawley (SD) rats were randomly divided into 3 groups: sham group (n=15), honokiol group (n=27) and vehicle group (n=27). After established CSCI model by a custom-made compressor successfully, the rats of sham group were subjected to the limited laminectomy without compression; the rats of honokiol group were subjected to CSCI surgery and intraperitoneal injection of 20 mg/kg honokiol; the rats of vehicle group were subjected to CSCI surgery and intraperitoneal injection of an equivalent volume of saline.Outcome measures: The locomotor function of each group was assessed using the Basso, Beattie and Bresnahan (BBB) rating scale. The pathological changes of myelinated nerve fibers of spinal cord in 3 groups were detected by osmic acid staining and transmission electron microcopy (TME). Immunofluorescence and Western blot were used to research the experessions of active caspase-3, caspase-12, cytochrome C and myelin basic protein (MBP) respectively.

RESULTS

In the vehicle group, the rats became paralyzed and spastic after injury, and the myelin sheath became swollen and broken down along with decreased number of myelinated nerve fibers. Western blot analysis manifested that active caspase-3, caspase-12 and cytochrome C began to increase 1 d after injury while the expression of MBP decreased gradually. After intervened with honokiol for 6 days, compared with the vehicle group, the locomotor function and the pathomorphological changes of myelin sheath of the CSCD rats were improved with obviously decreased expression of active caspase-3, caspase-12 and cytochrome C.

CONCLUSIONS

Honokiol may improve locomotor function and protect neural myelin sheat from demyelination via prevention oligodendrocytes (OLs) apoptosis through mediate endoplasmic reticulum (ER)-mitochondria pathway after CSCI.

Minocycline Alleviates White Matter Injury following Intracerebral Hemorrhage by Regulating CD4+ T Cell Differentiation via Notch1 Signaling Pathway

Neuroinflammation is a major reason for white matter injury (WMI) after intracerebral hemorrhage (ICH). Apart from microglia/macrophage activation, T cells also play an important role in regulating immune responses after ICH. In a previous study, we have revealed the role of minocycline in modulating microglia/macrophage activation after ICH. However, the exact mechanisms of minocycline in regulating T cells differentiation after ICH are still not well understood. Hence, this study explored the relationship between minocycline and CD4⁺ T cell differentiation after ICH. Piglet ICH model was used to investigate naive CD4⁺ T cell differentiation and T cells signal gene activation after ICH with immunofluorescence and whole transcriptome sequencing. Naive CD4⁺ T cells and primary oligodendrocyte coculture model were established to explore the effect and mechanism of minocycline in modulating CD4⁺ T cell differentiation after ICH. Flow cytometry was used to indicate CD4⁺ T cell differentiation after ICH. The mechanism of minocycline in modulating CD4⁺ T cell differentiation was demonstrated with immunofluorescence and western blot. Double immunostaining of representative CD4⁺ T cell marker CD3 and different subtype CD4⁺ T cell assisted proteins (IL17, IL4, Foxp3, and IFNγ) demonstrated naive CD4⁺ T cell differentiation in piglet after ICH. Whole transcriptome sequencing for perihematomal white matter sorted from piglet brains indicated T cell signal gene activation after ICH. The results of luxol fast blue staining, immunofluorescent staining, and electron microscopy showed that minocycline alleviated white matter injury after ICH in piglets. For our in vitro model, minocycline reduced oligodendrocyte injury and neuroinflammation by regulating CD4⁺ T cell differentiation after ICH. Moreover, minocycline increased the expression of NOTCH1, ACT1, RBP-J, and NICD1 in cultured CD4⁺ T cell when stimulated with hemoglobin. Hence, minocycline treatment could modulate naive CD4⁺ T cell differentiation and attenuate white matter injury via regulating Notch1 signaling pathway after ICH.

Clemastine Enhances Myelination, Delays Axonal Loss and Promotes Functional Recovery in Spinal Cord Injury

Recent evidence has shown that demyelination occurs along with axonal degeneration in spinal cord injury (SCI) during the secondary injury phase. Oligodendrocyte precursor cells (OPC) are present in the lesions but fail to differentiate into mature oligodendrocytes and form new myelin. Given the limited recovery of neuronal functions after SCI in adults without effective treatment available so far, it remains unknown whether enhancing OPC differentiation and myelination could benefit the recovery of SCI. To show the significance of myelin regeneration after SCI, the injury was treated with clemastine in the rat model. Clemastine is an FDA-approved drug that is potent in promoting oligodendrocyte differentiation and myelination in vivo, for four weeks following SCI. Motor function was assessed using sloping boards and grid walking tests and scored according to the Basso, Beattie, and Bresnahan protocol. The myelin integrity and protein expression were evaluated using transmission electron microscopy and immunofluorescence, respectively. The results indicated that clemastine treatment preserves myelin integrity, decreases loss of axons and improves functional recovery in the rat SCI model. The presented data suggest that myelination-enhancing strategies may serve as a potential therapeutic approach for the functional recovery in SCI.

Effect of Schwann cell transplantation combined with electroacupuncture on axonal regeneration and remyelination in rats with spinal cord injury

Axonal impairment and demyelination after compressed spinal cord injury lead to serious neurological dysfunction. Increasing studies have suggested that Schwann cells (SCs) transplantation is a reliable, effective, and promising method for treating spinal cord injury. However, single SCs transplantation is insufficient to promote the full recovery of neurological function. Additional approaches are required to support SCs transplantation as a treatment for spinal cord injury. In the study, we investigated whether the combination of electroacupuncture (EA) and SCs transplantation was a reliable intervention for spinal cord injury. We found that rats in the combination group had significantly higher functional locomotor scores than those received single treatment. By immunostaining, we found EA can not only improve survival and proliferation of transplanted SCs but also inhibit SC apoptosis and block the formation of an astrocytic scar. Additionally, EA promoted regenerated axons extending "bullet-shaped" growth cones into the lesion. Remarkably, EA can modify astrogliosis to promote axonal regeneration following SCs transplantation through inducing extension of astrocytic processes in the SCs graft interface. More importantly, the combination of SCs engraftment and EA can enhance corticospinal-tract axonal regeneration and remyelination after spinal cord injury through up-regulating neuregulin 1 type III in SCs and its downstream signaling mediators. Thus, it is concluded that SCs effectively promote axonal recovery after spinal cord injury when combined with EA stimulation. The experimental results have reinforced the theoretical basis of EA for its clinical efficacy in patients with spinal cord injury and merited further investigation for potential clinical application.

Ginkgolide B promotes oligodendrocyte precursor cell differentiation and survival via Akt/CREB/bcl-2 signaling pathway after white matter lesion

White matter lesion (WML) is caused by chronic cerebral hypoperfusion, which are usually associated with cognitive impairment. Evidence from recent studies has shown that ginkgolide B has a neuroprotective effect that could be beneficial for the treatment of ischemia; however, it is not clear whether ginkgolide B has a protective effect on WML. Our data show that ginkgolide B can promote the differentiation of oligodendrocyte precursor cell (OPC) into oligodendrocytes and promote oligodendrocyte survival following a WML. Ginkgolide B (5, 10, 20 mg/kg) or saline is administered intraperitoneally every day after WML. After 4 weeks, the data of Morris water maze suggested that rats' memory and learning abilities were impaired, and the administration of ginkgolide B enhanced behavioral achievement. Also, treatment with ginkgolide B significantly attenuated this loss of myelin. Our result suggests that ginkgolide B promotes the differentiation of OPC into oligodendrocytes. We also found that ginkgolide B ameliorates oligodendrocytes apoptosis. Furthermore, ginkgolide B enhanced the expression of phosphorylated Akt and CREB. In conclusion, our data firstly show that ginkgolide B promotes oligodendrocyte genesis and oligodendrocyte myelin following a WML, possibly involving the Akt and CREB pathways.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

Role of curcumin and its nanoformulations in neurotherapeutics: A comprehensive review

Curcumin, a dietary polyphenol and major constituent of Curcuma longa (Zingiberaceae), is extensively used as a spice in Asian countries. For ages, turmeric has been used in traditional medicine systems to treat various diseases, which was possible because of its anti-inflammatory, antioxidant, anticancerous, antiepileptic, antidepressant, immunomodulatory, neuroprotective, antiapoptotic, and antiproliferative effects. Curcumin has potent antioxidant, anti-inflammatory, antiapoptotic, neurotrophic activities, which support its plausible neuroprotective effects in neurodegenerative disease. However, there is limited information available regarding the clinical efficacy of curcumin in neurodegenerative cases. The low oral bioavailability of curcumin may be speculated as a plausible factor that limits its effects in humans. Therefore, utilization of several approaches for the enhancement of bioavailability may improve clinical outcomes. Furthermore, the use of nanotechnology and a targeted drug delivery system may improve the bioavailability of curcumin. The present review is designed to summarize the molecular mechanisms pertaining to the neuroprotective effects of curcumin and its nanoformulations.

Minocycline reduces intracerebral hemorrhage-induced white matter injury in piglets

Aims

White matter (WM) injury after intracerebral hemorrhage (ICH) results in poor or even fatal outcomes. As an anti‐inflammatory drug, minocycline has been considered a promising choice to treat brain injury after ICH. However, whether minocycline can reduce WM injury after ICH is still controversial. In the present study, we investigate the effect and underlying mechanism of minocycline on WM injury after ICH.

Methods

An ICH model was induced by an injection of autologous blood into the right frontal lobe of piglets. First, transcriptional analysis was performed at day 1 or 3 to investigate the dynamic changes in neuroinflammatory gene expression in WM after ICH. Second, ICH piglets were treated either with minocycline or with vehicle alone. All piglets then underwent magnetic resonance imaging to measure brain swelling. Brain tissue was used for real‐time polymerase chain reaction (RT‐PCR), immunohistochemistry, Western blot, and electron microscopy.

Results

Transcriptional analysis demonstrated that transforming growth factor‐β (TGF‐β)/mitogen‐activated protein kinase (MAPK) signaling is associated with microglia/macrophage‐mediated inflammation activation after ICH and is then involved in WM injury after ICH in piglets. Minocycline treatment results in less ICH‐induced brain swelling, fewer neurological deficits, and less WM injury in comparison with the vehicle alone. In addition, minocycline reduces microglial activation and alleviates demyelination in white matter after ICH. Finally, we found that minocycline attenuates WM injury by increasing the expression of TGF‐β and suppressing MAPK activation after ICH.

Conclusion

These results indicate that TGF‐β–mediated MAPK signaling contributes to WM injury after ICH, which can be altered by minocycline treatment.

APC-Cdh1 Inhibits the Proliferation and Activation of Oligodendrocyte Precursor Cells after Mechanical Stretch Injury

The incidence of spinal cord injury (SCI) continues to increase; however, the involved mechanisms remain unclear. Anaphase promoting complex (APC) and its regulatory subunit Cdh1 play important roles in the growth, development, and repair of the central nervous system (CNS). Cdh1 is involved in the pathophysiological processes of neuronal apoptosis and astrocyte-reactive proliferation after ischemic brain injury, whereas the role played by APC-Cdh1 in the proliferation and activation of oligodendrocyte precursor cells (OPCs) after SCI remains unresolved. Using primary cultures of spinal oligodendrocyte precursor cells, we successfully established an in vitro mechanical stretch injury model to simulate SCI. Cell viability and proliferation were determined by MTT assay and flow cytometric analysis of the cell cycle. Real-time fluorescent quantitative PCR and Western blot analysis determined the mRNA and protein expression levels of Cdh1 and its downstream substrates Skp2 and Id2. Mechanical stretch injury decreased the proliferative activity of OPCs and enhanced cellular Cdh1 expression. Dampened expression of Cdh1 in primary OPCs significantly promoted proliferation and activation of OPCs after SCI. In addition, the expression of the downstream substrates of Cdh1, Skp2, and Id2 was decreased following mechanical injury, whereas adenovirus-mediated Cdh1 RNA interference increased postinjury expression of Skp2 and Id2. These findings suggest that APC-Cdh1 might be involved in regulating the proliferation and activation of OPCs after mechanical SCI. Moreover, degraded ubiquitination of the downstream substrates Skp2 and Id2 might play an important role, at least in part, in the beneficial effects of OPCs activity following SCI.

Study on the pathological and biomedical characteristics of spinal cord injury by confocal Raman microspectral imaging

Confocal Raman microspectral imaging (CRMI) in combination with multivariate analysis was used to study pathological progression after spinal cord injury (SCI). By establishing moderate contusion in rat models, ex vivo longitudinal spinal cord tissue sections were prepared for microspectroscopic analysis. Comparative studies were then performed to determine the pathological distinctions among before injury (BI), one day post-injury (1 DPI), seven days post-injury (7 DPI), and 14 days post-injury (14 DPI) groups. Multivariate analysis algorithms, including K-mean cluster analysis (KCA) and principal component analysis (PCA), were conducted to highlight biochemical and structural variations after tissue damage. It is confirmed that typical spectral features and profiles can illustrate some fundamental and significant pathological processes post-injury, such as neuron apoptosis, hemorrhage, demyelination, and chondroitin sulfate proteoglycans (CSPGs) upregulation. Further, by establishing spectra-structure correlations, the reconstructed spectral images revealed some minute and important morphological characteristics following tissue injury, such as glial scar formation surrounding the cavity structure. The observed spectral phenomena also provide a detailed view on relevant pathobiological factors, which are involved in the spread of secondary damage after traumatic spinal cord injury. Our findings not only provide a spectral perspective to the well-known cellular mechanisms underlying SCI, but further provide a sound basis for developing real-time Raman methodologies to evaluate the prognostic factors and therapeutic results of SCI.

Axonal degeneration and demyelination following traumatic spinal cord injury: A systematic review and meta-analysis

The pathophysiology of spinal cord injury (SCI) related processes of axonal degeneration and demyelination are poorly understood. The present systematic review and meta-analysis were performed such to establish quantitative results of animal studies regarding the role of injury severity, SCI models and level of injury on the pathophysiology of axon and myelin sheath degeneration. 39 related articles were included in the analysis. The compiled data showed that the total number of axons, number of myelinated axons, myelin sheath thickness, axonal conduction velocity, and internode length steadily decreased as time elapsed from the injury (P_{for trend}<0.0001). The rate of axonal retrograde degeneration was affected by SCI model and severity of the injury. Axonal degeneration was higher in injuries of the thoracic region. The SCI model and the site of the injury also affected axonal retrograde degeneration. The number of myelinated axons in the caudal region of the injury was significantly higher than the lesion site and the rostral region. The findings of the present meta-analysis show that the pathophysiology of axons and myelin sheath differ in various phases of SCI and are affected by multiple factors related to the injury.

Oligodendrogliogenesis and Axon Remyelination after Traumatic Spinal Cord Injuries in Animal Studies: A Systematic Review

Extensive oligodendrocyte death after acute traumatic spinal cord injuries (TSCI) leads to axon demyelination and subsequently may leave axons vulnerable to degeneration. Despite the present evidence showing spontaneous remyelination after TSCI the cellular origin of new myelin and the time course of the axon ensheathment/remyelination remained controversial issue. In this systematic review the trend of oligodendrocyte death after injury as well as the extent and the cellular origin of oligodendrogliogenesis were comprehensively evaluated. The study design was based on Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-guided systematic review. PubMed and EMBASE were searched with no temporal or linguistic restrictions. Also, hand-search was performed in the bibliographies of relevant articles. Non-interventional animal studies discussing different types of myelinating cells including oligodendrocytes, Schwann cells and oligodendrocyte progenitor cells (OPCs) were evaluated. The extent of oligodendrocyte death, oligodendrocyte differentiation and remyelination were the pathophysiological outcome measures. We found 12,359 studies, 34 of which met the inclusion criteria. The cumulative evidence shows extensive oligodendrocytes cell death during the first week post-injury (pi). OPCs and peripheral invading Schwann cells are the dominant cells contributing in myelin formation. The maximum OPC proliferation was observed at around 2 weeks pi and oligodendrogliogenesis continues at later stages until the number of oligodendrocytes return to normal tissue by one month pi. Taken together, the evidence in animals reveals the potential role for endogenous myelinating cells in the axon ensheathment/remyelination after TSCI and this can be the target of pharmacotherapy to induce oligodendrocyte differentiation and myelin formation post-injury.

Endoplasmic reticulum stress induces apoptosis of arginine vasopressin neurons in central diabetes insipidus via PI3K/Akt pathway

Aims

Central diabetes insipidus (CDI), a typical complication caused by pituitary stalk injury, often occurs after surgery, trauma, or tumor compression around hypothalamic structures such as the pituitary stalk and optic chiasma. CDI is linked to decreased arginine vasopressin (AVP) neurons in the hypothalamic supraoptic nucleus and paraventricular nucleus, along with a deficit in circulating AVP and oxytocin. However, little has been elucidated about the changes in AVP neurons in CDI. Hence, our study was designed to understand the role of several pathophysiologic changes such as endoplasmic reticulum (ER) stress and apoptosis of AVP neurons in CDI.

Methods

In a novel pituitary stalk electric lesion (PEL) model to mimic CDI, immunofluorescence and immunoblotting were used to understand the underlying regulatory mechanisms.

Results

We reported that in CDI condition, generated by PEL, ER stress induced apoptosis of AVP neurons via activation of the PI3K/Akt and ERK pathways. Furthermore, application of N‐acetylcysteine protected hypothalamic AVP neurons from ER stress‐induced apoptosis through blocking the PI3K/Akt and ERK pathways.

Conclusion

Our findings showed that AVP neurons underwent apoptosis induced by ER stress, and ER stress might play a vital role in CDI condition through the PI3K/Akt and ERK pathways.

Insights in pathogenesis of multiple sclerosis: nitric oxide may induce mitochondrial dysfunction of oligodendrocytes

Demyelinating diseases, such as multiple sclerosis (MS), are kinds of common diseases in the central nervous system (CNS), and originated from myelin loss and axonal damage. Oligodendrocyte dysfunction is the direct reason of demyelinating lesions in the CNS. Nitric oxide (NO) plays an important role in the pathological process of demyelinating diseases. Although the neurotoxicity of NO is more likely mediated by peroxynitrite rather than NO itself, NO can impair oligodendrocyte energy metabolism through mediating the damaging of mitochondrial DNA, mitochondrial membrane and mitochondrial respiratory chain complexes. In the progression of MS, NO can mainly mediate demyelination, axonal degeneration and cell death. Hence, in this review, we extensively discuss endangerments of NO in oligodendrocytes (OLs), which is suggested to be the main mediator in demyelinating diseases, e.g. MS. We hypothesize that NO takes part in MS through impairing the function of monocarboxylate transporter 1, especially causing axonal degeneration. Then, it further provides a new insight that NO for OLs may be a reliable therapeutic target to ameliorate the course of demyelinating diseases.

Beneficial Effects of Resveratrol-Mediated Inhibition of the mTOR Pathway in Spinal Cord Injury

Spinal cord injury (SCI) causes a high rate of morbidity and disability. The clinical features of SCI are divided into acute, subacute, and chronic phases according to its pathophysiological events. The mammalian target of rapamycin (mTOR) signaling pathway plays an important role in cell death and inflammation in the acute phase and neuroregeneration in the subacute/chronic phases at different times. Resveratrol has the potential of regulating cell growth, proliferation, metabolism, and angiogenesis through the mTOR signaling pathway. Herein, we explicate the role of resveratrol in the repair of SCI through the inhibition of the mTOR signaling pathway. The inhibition of the mTOR pathway by resveratrol has the potential of serving as a neuronal restorative mechanism following SCI.

Dl-3-n-butylphthalide prevents the disruption of blood-spinal cord barrier via inhibiting endoplasmic reticulum stress following spinal cord injury

After spinal cord injury (SCI), the destruction of blood-spinal cord barrier (BSCB) is shown to accelerate gathering of noxious blood-derived components in the nervous system, leading to secondary neurodegenerative damages. SCI activates endoplasmic reticulum stress (ER stress), which is considered to evoke secondary damages of neurons and glia. Recent evidence indicates that Dl-3-n-butylphthalide (NBP) has the neuroprotective effect in ischaemic brain injury, but whether it has protective effects on SCI or not is largely unclear. Here, we show that NBP prevented BSCB disruption after SCI via inhibition of ER stress. Following a moderate contusion injury of the T9 level of spinal cord, NBP was administered by oral gavage and further treated once a day. NBP significantly attenuated BSCB permeability and breakdown of adherens junction (AJ) and tight junction (TJ) proteins, then improved locomotion recovery following SCI. The protective role of NBP on BSCB disruption is associated with the restrain of ER stress caused by SCI. Furthermore, NBP considerably constrained the expression of ER stress-associated proteins and degradation of TJ and AJ in human brain microvascular endothelial cells (HBMECs) treated with TG. In conclusion, our results indicate that ER stress is associated with the disruption of BSCB integrity after injury, NBP attenuates BSCB disruption via inhibiting ER stress and improve functional recovery following SCI.

A novel translocator protein 18 kDa ligand, ZBD-2, exerts neuroprotective effects against acute spinal cord injury

Traumatic spinal cord injury (SCI) happens accidently and often leads to motor dysfunction due to a series of biochemical and pathological events and damage, either temporarily or permanently. Translocator protein 18 (TSPO) has been found to be involved in the synthesis of endogenous neurosteroids which have multiple effects on neurons, but the internal mechanisms are not clear. N-benzyl-N-ethyl-2-(7,8-oxo-2-phenyl-9H-purin-9-yl) acetamide (ZBD-2), a newly reported ligand of TSPO, shows some neuroprotective effect against focal cerebral ischemia in vivo and NMDA-induced neurotoxicity in vitro. The present study aims to examine the role of ZBD-2 in SCI mice and elucidate the underlying molecular mechanisms. The SCI model was established by crushing spinal cord. ZBD-2 (10 mg/kg) significantly enhanced the hindlimb locomotor functions after SCI and decreased the tissue damage and conserved the white matter of the spinal cord. High-dose ZBD-2 alleviated the oxidative stress induced by SCI and regulated the imbalance between NR2B-containing NMDA and GABA receptors by increasing the levels of GAD67 in the spinal cord of SCI mice. Additionally, ZBD-2 (10 mg/kg) increased phosphorylated Akt (p-Akt) and decreased the ratio of Bax/Bcl-2. These results demonstrate that ZBD-2 performs neuroprotection against SCI through regulating the synaptic transmission and the PI3K/AKT signaling pathway.

G-1 exerts neuroprotective effects through G protein-coupled estrogen receptor 1 following spinal cord injury in mice

Spinal cord injury (SCI) always occurs accidently and leads to motor dysfunction because of biochemical and pathological events. Estrogen has been shown to be neuroprotective against SCI through estrogen receptors (ERs), but the underlying mechanisms have not been fully elucidated. In the present study, we investigated the role of a newly found membrane ER, G protein-coupled estrogen receptor 1 (GPR30 or GPER1), and discussed the feasibility of a GPR30 agonist as an estrogen replacement. Forty adult female C57BL/6J mice (10-12 weeks old) were divided randomly into vehicle, G-1, E2, G-1 + G-15 and E2 + G-15 groups. All mice were subjected to SCI using a crushing injury approach. The specific GPR30 agonist, G-1, mimicked the effects of E2 treatment by preventing SCI-induced apoptotic cell death and enhancing motor functional recovery after injury. GPR30 activation regulated phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK/extracellular signal-regulated kinase (ERK) signalling pathways, increased GPR30 and anti-apoptosis proteins Bcl-2 and brain derived neurotrophic factor (BDNF), but decreased the pro-apoptosis factor Bax and cleaved caspase-3. However, the neuroprotective effects of G-1 and E2 were blocked by the specific GPR30 antagonist, G-15. Thus, GPR30 rather than classic ERs is required to induce estrogenic neuroprotective effects. Given that estrogen replacement therapy may cause unexpected side effects, especially on the reproductive system, GPR30 agonists may represent a potential therapeutic approach for treating SCI.

Oligodendrocyte Precursor Cells in Spinal Cord Injury: A Review and Update

Spinal cord injury (SCI) is a devastating condition to individuals, families, and society. Oligodendrocyte loss and demyelination contribute as major pathological processes of secondary damages after injury. Oligodendrocyte precursor cells (OPCs), a subpopulation that accounts for 5 to 8% of cells within the central nervous system, are potential sources of oligodendrocyte replacement after SCI. OPCs react rapidly to injuries, proliferate at a high rate, and can differentiate into myelinating oligodendrocytes. However, posttraumatic endogenous remyelination is rarely complete, and a better understanding of OPCs' characteristics and their manipulations is critical to the development of novel therapies. In this review, we summarize known characteristics of OPCs and relevant regulative factors in both health and demyelinating disorders including SCI. More importantly, we highlight current evidence on post-SCI OPCs transplantation as a potential treatment option as well as the impediments against regeneration. Our aim is to shed lights on important knowledge gaps and to provoke thoughts for further researches and the development of therapeutic strategies.

Acetyl-L-carnitineameliorates mitochondrial damage and apoptosis following spinal cord injury in rats

Acetyl-l-carnitine (ALC) facilitates the entry and exit of fatty acids from mitochondria and plays an essential role in energy metabolism. Although ALC is known to exert neuroprotective effects in multiple neurological diseases, its effects on spinal cord injury (SCI)-induced mitochondrial impairments and apoptosis remain unclear. In this study, we aimed to evaluate the putative effects of ALC on mitochondrial dysfunction and apoptosis induced by SCI in a rodent model. Our results indicate that SCI elicits dynamic alternations in the expression of mitochondria-related proteins. Transmission electron microscopy analysis showed that ALC administration abrogated key ultrastructural abnormalities in mitochondria at 24h after SCI by maintaining mitochondrial length, reducing the number of damaged mitochondria, and reversing mitochondrial score (P<0.05 compared with SCI group). In addition, ALC administration maintained the mitochondrial membrane potential and mitochondrial Na(+)-K(+)-ATPase activity following SCI (P<0.05 compared with SCI group). ALC administration reversed the downregulation of mitofusin 1 (Mfn1), Mfn2, Bcl-2, and the upregulation of dynamin-related protein 1 (Drp1), mitochondrial fission 1 (Fis1), Bcl-2-associated X protein (Bax) and cytosol cytochrome c (cyto-CytC) induced by SCI (P<0.05 compared with SCI group). Finally ALC administration greatly reduced the percentage of apoptotic cells compared with the SCI group (P<0.01). In conclusion, our findings demonstrated that ALC ameliorated SCI-induced mitochondrial structural alternations, mitochondrial dysfunction, and apoptosis.

Protective Effect of Electroacupuncture on Neural Myelin Sheaths is Mediated via Promotion of Oligodendrocyte Proliferation and Inhibition of Oligodendrocyte Death After Compressed Spinal Cord Injury

Electroacupuncture (EA) has been used worldwide to treat demyelinating diseases, but its therapeutic mechanism is poorly understood. In this study, a custom-designed model of compressed spinal cord injury (CSCI) was used to induce demyelination. Zusanli (ST36) and Taixi (KI3) acupoints of adult rats were stimulated by EA to demonstrate its protective effect. At 14 days after EA, both locomotor skills and ultrastructural features of myelin sheath were significantly improved. Phenotypes of proliferating cells were identified by double immunolabeling of 5-ethynyl-2'-deoxyuridine with antibodies to cell markers: NG2 [oligodendrocyte precursor cell (OPC) marker], 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) (oligodendrocyte marker), and glial fibrillary acidic protein (GFAP) (astrocyte marker). EA enhanced the proliferation of OPCs and CNPase, as well as the differentiation of OPCs by promoting Olig2 (the basic helix-loop-helix protein) and attenuating Id2 (the inhibitor of DNA binding 2). EA could also improve myelin basic protein (MBP) and protect existing oligodendrocytes from apoptosis by inhibiting caspase-12 (a representative of endoplasmic reticulum stress) and cytochrome c (an apoptotic factor and hallmark of mitochondria). Therefore, our results indicate that the protective effect of EA on neural myelin sheaths is mediated via promotion of oligodendrocyte proliferation and inhibition of oligodendrocyte death after CSCI.

Silencing of JMJD2B induces cell apoptosis via mitochondria-mediated and death receptor-mediated pathway activation in colorectal cancer

OBJECTIVE

To investigate the molecular mechanism of colorectal cancer (CRC) cell apoptosis induced by the Jumonji domain containing 2B (JMJD2B) silencing.

METHODS

Both HCT116 and LoVo CRC cell lines were used for analyses. Cell apoptosis after JMJD2B silencing was determined by flow cytometry. JC-1 fluorescence probe was applied to measure the mitochondrial outer membrane permeabilization by flow cytometry and fluorescence microscopy. Immunofluorescence was used to detect cytochrome C translocation from mitochondria to cytosol after JMJD2B silencing. The efficacy of JMJD2B silencing on the protein levels of Bcl-2 family, caspase proteins, CCAAT/enhancer binding protein homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) were detected by Western blot.

RESULTS

JMJD2B silencing induced CRC cell apoptosis via a decrease of the anti-apoptotic gene Bcl-2 family expression, leading to the translocation of Bak and Bax proteins and the promotion of mitochondrial membrane disruption, resulting in the release of cytochrome C from mitochondria and subsequent caspase-9 and caspase-3 cleavage. It also increased the amount of cleaved caspase-8 involved in the death receptor-related apoptotic pathway. Bcl-2 homology 3 interacting-domain death agonist (Bid), a specific caspase-8 substrate involved in the Fas signaling pathway, subsequently induced cleavage via caspase-8 activation. However, levels of CHOP and GRP78 remained unchanged after JMJD2B silencing.

CONCLUSIONS

JMJD2B silencing induced CRC cell apoptosis via both mitochondria-related and death receptor-related pathways. The cleavage of Bid activated by caspase-8 might serve as a crosstalk mediator between these two pathways in CRC.