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Table of Content

    15 June 2023, Volume 18 Issue 6 Previous Issue   
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    Neuro faces of beneficial T cells: essential in brain, impaired in aging and neurological diseases, and activated functionally by neurotransmitters and neuropeptides
    Mia Levite
    2023, 18 (6):  1165-1178.  doi: 10.4103/1673-5374.357903
    Abstract ( 110 )   PDF (4413KB) ( 65 )   Save
    T cells are essential for a healthy life, performing continuously: immune surveillance, recognition, protection, activation, suppression, assistance, eradication, secretion, adhesion, migration, homing, communications, and additional tasks. This paper describes five aspects of normal beneficial T cells in the healthy or diseased brain. First, normal beneficial T cells are essential for normal healthy brain functions: cognition, spatial learning, memory, adult neurogenesis, and neuroprotection. T cells 
    decrease secondary neuronal degeneration, increase neuronal survival after central nervous system (CNS) injury, and limit CNS inflammation and damage upon injury and infection. Second, while pathogenic T cells contribute to CNS disorders, recent studies, mostly in animal models, show that specific subpopulations of normal beneficial T cells have protective and regenerative effects in several neuroinflammatory and neurodegenerative diseases. These include Multiple Sclerosis (MS), Alzheimer’s disease, Parkinson’s disease, Amyotrophic Lateral Sclerosis (ALS), stroke, CNS trauma, chronic pain, and others. Both T cell-secreted molecules and direct cell-cell contacts deliver T cell neuroprotective, neuroregenerative and immunomodulatory effects. Third, normal beneficial T cells are abnormal, impaired, and dysfunctional in aging and multiple neurological diseases. Different T cell impairments are evident in aging, brain tumors (mainly Glioblastoma), severe viral infections (including COVID-19), chronic stress, major depression, schizophrenia, Parkinson’s disease, Alzheimer’s disease, ALS, MS, stroke, and other neuro-pathologies. The main detrimental mechanisms that impair T cell function are activation-induced cell death, exhaustion, senescence, and impaired T cell stemness. Fourth, several physiological neurotransmitters and neuropeptides induce by themselves multiple direct, potent, beneficial, and therapeutically-relevant effects on normal human T cells, via their receptors in T cells. This scientific field is called “Nerve-Driven Immunity”. The main neurotransmitters and neuropeptides that induce directly activating and beneficial effects on naïve normal human T cells are: dopamine, glutamate, GnRH-II, neuropeptide Y, calcitonin gene-related peptide, and somatostatin. Fifth, “Personalized Adoptive Neuro-Immunotherapy”.  This is a novel unique cellular immunotherapy, based on the “Nerve-Driven Immunity” findings, which was recently designed and patented for safe and repeated rejuvenation, activation, and improvement of impaired and dysfunctional T cells of any person in need, by ex vivo exposure of the person’s T cells to neurotransmitters and neuropeptides. Personalized adoptive neuro-immunotherapy includes an early ex vivo personalized diagnosis, and subsequent ex vivo → in vivo personalized adoptive therapy, tailored according to the diagnosis. The Personalized Adoptive Neuro-Immunotherapy has not yet been tested in humans, pending validation of safety and efficacy in clinical trials, especially in brain tumors, chronic infectious diseases, and aging, in which T cells are exhausted and/or senescent and dysfunctional.
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    Profiling neuroprotective potential of trehalose in animal models of neurodegenerative diseases: a systematic review
    Kah Hui Yap, Shahrul Azmin, Suzana Makpol, Hanafi Ahmad Damanhuri, Muzaimi Mustapha, Jemaima Che Hamzah, Norlinah Mohamed Ibrahim
    2023, 18 (6):  1179-1185.  doi: 10.4103/1673-5374.360164
    Abstract ( 165 )   PDF (791KB) ( 96 )   Save
    Trehalose, a unique nonreducing crystalline disaccharide, is a potential disease-modifying treatment for neurodegenerative diseases associated with protein misfolding and aggregation due to aging, intrinsic mutations, or autophagy dysregulation. This systematic review summarizes the effects of trehalose on its underlying mechanisms in animal models of selected neurodegenerative disorders (tau pathology, synucleinopathy, polyglutamine tract, and motor neuron diseases). All animal studies on neurodegenerative diseases treated with trehalose published in Medline (accessed via EBSCOhost) and Scopus were considered. Of the 2259 studies screened, 29 met the eligibility criteria. According to the SYstematic Review Center for Laboratory Animal Experiment (SYRCLE) risk of bias tool, we reported 22 out of 29 studies with a high risk of bias. The present findings support the purported role of trehalose in autophagic flux and protein refolding. This review identified several other lesser-known pathways, including modifying amyloid precursor protein processing, inhibition of reactive gliosis, the integrity of the blood-brain barrier, activation of growth factors, upregulation of the downstream antioxidant signaling pathway, and protection against mitochondrial defects. The absence of adverse events and improvements in the outcome parameters were observed in some studies, which supports the transition to human clinical trials. It is possible to conclude that trehalose exerts its neuroprotective effects through both direct and indirect pathways. However, heterogeneous methodologies and outcome measures across the studies rendered it impossible to derive a definitive conclusion. Translational studies on trehalose would need to clarify three important questions: 1) bioavailability with oral administration, 2) optimal time window to confer neuroprotective benefits, and 3) optimal dosage to confer neuroprotection. 
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    Cdk5 and aberrant cell cycle activation at the core of neurodegeneration
    Raquel Requejo-Aguilar
    2023, 18 (6):  1186-1190.  doi: 10.4103/1673-5374.360165
    Abstract ( 106 )   PDF (2484KB) ( 71 )   Save
    Neurodegenerative diseases are caused by the progressive loss of specific neurons. The exact mechanisms of action of these diseases are unknown, and many studies have focused on pathways related to abnormal accumulation and processing of proteins, mitochondrial dysfunction, and oxidative stress leading to apoptotic death. However, a growing body of evidence indicates that aberrant cell cycle re-entry plays a major role in the pathogenesis of neurodegeneration. The activation of the cell cycle in mature neurons could be promoted by several signaling mechanisms, including c-Jun N-terminal kinases, p38 mitogen-activated protein kinases, and mitogen-activated protein kinase/extracellular signal-regulated kinase cascades; post-translational modifications such as Tau-phosphorylation; and DNA damage response. In all these events, implicated Cdk5, a proline-directed serine/threonine protein kinase, seems to be responsible for several cellular processes in neurons including axon growth, neurotransmission, synaptic plasticity, neuronal migration, and maintenance of neuronal survival. However, under pathological conditions, Cdk5 dysregulation may lead to cell cycle re-entry in post-mitotic neurons. Thus, Cdk5 hyperactivation, by its physiologic activator p25, hyper-phosphorylates downstream substrates related to neurodegenerative diseases. This review summarizes factors such as oxidative stress, DNA damage response, signaling pathway disturbance, and Ubiquitin proteasome malfunction contributing to cell cycle re-entry in post-mitotic neurons. It also describes how all these factors are linked to a greater or lesser extent with Cdk5. Thus, it offers a global vision of the function of cell cycle-related proteins in mature neurons with a focus on Cdk5 and how this protein contributes to the development of Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and Huntington’s disease by cell cycle activation.  
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    Recent advancements in noninvasive brain modulation for individuals with autism spectrum disorder
    Jessica R. Griff, Jake Langlie, Nathalie B. Bencie, Zachary J. Cromar, Jeenu Mittal, Idil Memis, Steven Wallace, Alexander E. Marcillo, Rahul Mittal, Adrien A. Eshraghi
    2023, 18 (6):  1191-1195.  doi: 10.4103/1673-5374.360163
    Abstract ( 125 )   PDF (603KB) ( 99 )   Save
    Autism spectrum disorder is classified as a spectrum of neurodevelopmental disorders with an unknown definitive etiology. Individuals with autism spectrum disorder show deficits in a variety of areas including cognition, memory, attention, emotion recognition, and social skills. With no definitive treatment or cure, the main interventions for individuals with autism spectrum disorder are based on behavioral modulations. Recently, noninvasive brain modulation techniques including repetitive transcranial magnetic stimulation, intermittent theta burst stimulation, continuous theta burst stimulation, and transcranial direct current stimulation have been studied for their therapeutic properties of modifying neuroplasticity, particularly in individuals with autism spectrum disorder. Preliminary evidence from small cohort studies, pilot studies, and clinical trials suggests that the various noninvasive brain stimulation techniques have therapeutic benefits for treating both behavioral and cognitive manifestations of autism spectrum disorder. However, little data is available for quantifying the clinical significance of these findings as well as the long-term outcomes of individuals with autism spectrum disorder who underwent transcranial stimulation. The objective of this review is to highlight the most recent advancements in the application of noninvasive brain modulation technology in individuals with autism spectrum disorder.
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    Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration
    Irene Villalón-García, Suleva Povea-Cabello, Mónica Álvarez-Córdoba, Marta Talaverón-Rey, Juan M. Suárez-Rivero, Alejandra Suárez-Carrillo, Manuel Munuera-Cabeza, Diana Reche-López, Paula Cilleros-Holgado, Rocío Piñero-Pérez, José A. Sánchez-Alcázar
    2023, 18 (6):  1196-1202.  doi: 10.4103/1673-5374.358614
    Abstract ( 126 )   PDF (743KB) ( 82 )   Save
    Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, or neurodegeneration with brain iron accumulation disorders. Mitochondrial dysfunction, lipofuscin accumulation, autophagy disruption, and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders. Currently, the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear. In this review, we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation, and the effect of iron overload on lipid peroxidation and cellular function. The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration. Therefore, the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration. In addition, we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration, particularly in PLA2G6-associated neurodegeneration, a rare neurodegenerative disease with autosomal recessive inheritance, which belongs to the group of neurodegeneration with brain iron accumulation disorders. 
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    Cell-based therapeutic strategies for treatment of spinocerebellar ataxias: an update
    Joana Sofia Correia, Sara Duarte-Silva, António José Salgado, Patrícia Maciel
    2023, 18 (6):  1203-1212.  doi: 10.4103/1673-5374.355981
    Abstract ( 110 )   PDF (771KB) ( 106 )   Save
    Spinocerebellar ataxias are heritable neurodegenerative diseases caused by a cytosine-adenine-guanine expansion, which encodes a long glutamine tract (polyglutamine) in the respective wild-type protein causing misfolding and protein aggregation. Clinical features of polyglutamine spinocerebellar ataxias include neuronal aggregation, mitochondrial dysfunction, decreased proteasomal activity, and autophagy impairment. Mutant polyglutamine protein aggregates accumulate within neurons and cause neural dysfunction and death in specific regions of the central nervous system. Spinocerebellar ataxias are mostly characterized by progressive ataxia, speech and swallowing problems, loss of coordination and gait deficits. Over the past decade, efforts have been made to ameliorate disease symptoms in patients, yet no cure is available. Previous studies have been proposing the use of stem cells as promising tools for central nervous system tissue regeneration. So far, pre-clinical trials have shown improvement in various models of neurodegenerative diseases following stem cell transplantation, including animal models of spinocerebellar ataxia types 1, 2, and 3. However, contrasting results can be found in the literature, depending on the animal model, cell type, and route of administration used. Nonetheless, clinical trials using cellular implants into degenerated brain regions have already been applied, with the expectation that these cells would be able to differentiate into the specific neuronal subtypes and re-populate these regions, reconstructing the affected neural network. Meanwhile, the question of how feasible it is to continue such treatments remains unanswered, with long-lasting effects being still unknown. To establish the value of these advanced therapeutic tools, it is important to predict the actions of the transplanted cells as well as to understand which cell type can induce the best outcomes for each disease. Further studies are needed to determine the best route of administration, without neglecting the possible risks of repetitive transplantation that these approaches so far appear to demand. Despite the challenges ahead of us, cell-transplantation therapies are reported to have transient but beneficial outcomes in spinocerebellar ataxias, which encourages efforts towards their improvement in the future.
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    Do tau-synaptic long-term depression interactions in the hippocampus play a pivotal role in the progression of Alzheimer’s disease?
    Zhengtao Hu, Tomas Ondrejcak, Pengpeng Yu, Yangyang Zhang, Yin Yang, Igor Klyubin, Sean P. Kennelly, Michael J. Rowan, Neng-Wei Hu
    2023, 18 (6):  1213-1219.  doi: 10.4103/1673-5374.360166
    Abstract ( 85 )   PDF (1233KB) ( 83 )   Save
    Cognitive decline in Alzheimer’s disease correlates with the extent of tau pathology, in particular tau hyperphosphorylation that initially appears in the transentorhinal and related regions of the brain including the hippocampus. Recent evidence indicates that tau hyperphosphorylation caused by either amyloid-β or long-term depression, a form of synaptic weakening involved in learning and memory, share similar mechanisms. Studies from our group and others demonstrate that long-term depression-inducing low-frequency stimulation triggers tau phosphorylation at different residues in the hippocampus under different experimental conditions including aging. Conversely, certain forms of long-term depression at hippocampal glutamatergic synapses require endogenous tau, in particular, phosphorylation at residue Ser396. Elucidating the exact mechanisms of interaction between tau and long-term depression may help our understanding of the physiological and pathological functions of tau/tau (hyper)phosphorylation. We first summarize experimental evidence regarding tau-long-term depression interactions, followed by a discussion of possible mechanisms by which this interplay may influence the pathogenesis of Alzheimer’s disease. Finally, we conclude with some thoughts and perspectives on future research about these interactions.
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    Neurotrophic factor-based pharmacological approaches in neurological disorders
    Margherita Alfonsetti#, Michele d’Angelo#, Vanessa Castelli
    2023, 18 (6):  1220-1228.  doi: 10.4103/1673-5374.358619
    Abstract ( 111 )   PDF (1202KB) ( 43 )   Save
    Aging is a physiological event dependent on multiple pathways that are linked to lifespan and processes leading to cognitive decline. This process represents the major risk factor for aging-related diseases such as Alzheimer’s disease, Parkinson’s disease, and ischemic stroke. The incidence of all these pathologies increases exponentially with age. Research on aging biology has currently focused on elucidating molecular mechanisms leading to the development of those pathologies. Cognitive deficit and neurodegeneration, common features of aging-related pathologies, are related to the alteration of the activity and levels of neurotrophic factors, such as brain-derived neurotrophic factor, nerve growth factor, and glial cell-derived neurotrophic factor. For this reason, treatments that modulate neurotrophin levels have acquired a great deal of interest in preventing neurodegeneration and promoting neural regeneration in several neurological diseases. Those treatments include both the direct administration of neurotrophic factors and the induced expression with viral vectors, neurotrophins’ binding with biomaterials or other molecules to increase their bioavailability but also cell-based therapies. Considering neurotrophins’ crucial role in aging pathologies, here we discuss the involvement of several neurotrophic factors in the most common brain aging-related diseases and the most recent therapeutic approaches that provide direct and sustained neurotrophic support.
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    Translational bioengineering strategies for peripheral nerve regeneration: opportunities, challenges, and novel concepts
    Karim A. Sarhane, Chenhu Qiu, Thomas G.W. Harris, Philip J. Hanwright, Hai-Quan Mao, Sami H. Tuffaha
    2023, 18 (6):  1229-1234.  doi: 10.4103/1673-5374.358616
    Abstract ( 144 )   PDF (4569KB) ( 100 )   Save
    Peripheral nerve injuries remain a challenging problem in need of better treatment strategies. Despite best efforts at surgical reconstruction and postoperative rehabilitation, patients are often left with persistent, debilitating motor and sensory deficits. There are currently no therapeutic strategies proven to enhance the regenerative process in humans. A clinical need exists for the development of technologies to promote nerve regeneration and improve functional outcomes. Recent advances in the fields of tissue engineering and nanotechnology have enabled biomaterial scaffolds to modulate the host response to tissue repair through tailored mechanical, chemical, and conductive cues. New bioengineered approaches have enabled targeted, sustained delivery of protein therapeutics with the capacity to unlock the clinical potential of a myriad of neurotrophic growth factors that have demonstrated promise in enhancing regenerative outcomes. As such, further exploration of combinatory strategies leveraging these technological advances may offer a pathway towards clinically translatable solutions to advance the care of patients with peripheral nerve injuries. This review first presents the various emerging bioengineering strategies that can be applied for the management of nerve gap injuries. We cover the rationale and limitations for their use as an alternative to autografts, focusing on the approaches to increase the number of regenerating axons crossing the repair site, and facilitating their growth towards the distal stump. We also discuss the emerging growth factor-based therapeutic strategies designed to improve functional outcomes in a multimodal fashion, by accelerating axonal growth, improving the distal regenerative environment, and preventing end-organs atrophy.  
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    Decoding degeneration: the implementation of machine learning for clinical detection of neurodegenerative disorders
    Fariha Khaliq, Jane Oberhauser, Debia Wakhloo, Sameehan Mahajani
    2023, 18 (6):  1235-1242.  doi: 10.4103/1673-5374.355982
    Abstract ( 133 )   PDF (784KB) ( 124 )   Save
    Machine learning represents a growing subfield of artificial intelligence with much promise in the diagnosis, treatment, and tracking of complex conditions, including neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. While no definitive methods of diagnosis or treatment exist for either disease, researchers have implemented machine learning algorithms with neuroimaging and motion-tracking technology to analyze pathologically relevant symptoms and biomarkers. Deep learning algorithms such as neural networks and complex combined architectures have proven capable of tracking disease-linked changes in brain structure and physiology as well as patient motor and cognitive symptoms and responses to treatment. However, such techniques require further development aimed at improving transparency, adaptability, and reproducibility. In this review, we provide an overview of existing neuroimaging technologies and supervised and unsupervised machine learning techniques with their current applications in the context of Alzheimer’s and Parkinson’s diseases.
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    Long-noncoding RNAs as epigenetic regulators in neurodegenerative diseases
    Paola Ruffo, Francesca De Amicis, Emiliano Giardina, Francesca Luisa Conforti
    2023, 18 (6):  1243-1248.  doi: 10.4103/1673-5374.358615
    Abstract ( 110 )   PDF (4067KB) ( 68 )   Save
    The growing and rapid development of high-throughput sequencing technologies have allowed a greater understanding of the mechanisms underlying gene expression regulation. Editing the epigenome and epitranscriptome directs the fate of the transcript influencing the functional outcome of each mRNA. In this context, non-coding RNAs play a decisive role in addressing the expression regulation at the gene and chromosomal levels. Long-noncoding RNAs, consisting of more than 200 nucleotides, have been shown to act as epigenetic regulators in several key molecular processes involving neurodegenerative disorders, such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis and Huntington’s disease. Long-noncoding RNAs are abundantly expressed in the central nervous system, suggesting that their deregulation could trigger neuronal degeneration through RNA modifications. The evaluation of their diagnostic significance and therapeutic potential could lead to new treatments for these diseases for which there is no cure.
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    The lymphatic system: a therapeutic target for central nervous system disorders
    Jia-Qi Xu, Qian-Qi Liu, Sheng-Yuan Huang, Chun-Yue Duan, Hong-Bin Lu, Yong Cao, Jian-Zhong Hu
    2023, 18 (6):  1249-1256.  doi: 10.4103/1673-5374.355741
    Abstract ( 510 )   PDF (2208KB) ( 236 )   Save
    The lymphatic vasculature forms an organized network that covers the whole body and is involved in fluid homeostasis, metabolite clearance, and immune surveillance. The recent identification of functional lymphatic vessels in the meninges of the brain and the spinal cord has provided novel insights into neurophysiology. They emerge as major pathways for fluid exchange. The abundance of immune cells in lymphatic vessels and meninges also suggests that lymphatic vessels are actively involved in neuroimmunity. The lymphatic system, through its role in the clearance of neurotoxic proteins, autoimmune cell infiltration, and the transmission of pro-inflammatory signals, participates in the pathogenesis of a variety of neurological disorders, including neurodegenerative and neuroinflammatory diseases and traumatic injury. Vascular endothelial growth factor C is the master regulator of lymphangiogenesis, a process that is critical for the maintenance of central nervous system homeostasis. In this review, we summarize current knowledge and recent advances relating to the anatomical features and immunological functions of the lymphatic system of the central nervous system and highlight its potential as a therapeutic target for neurological disorders and central nervous system repair.
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    Plasticity of callosal neurons in the contralesional cortex following traumatic brain injury
    Alexandra Chovsepian, Laura Empl, Florence M. Bareyre
    2023, 18 (6):  1257-1258.  doi: 10.4103/1673-5374.360167
    Abstract ( 90 )   PDF (542KB) ( 70 )   Save
    Traumatic brain injury (TBI) represents a significant cause of disability worldwide. It creates a vast array of damaging macro- and microscopic changes in the affected brain area(s), ranging from neuronal cell death, changes in structural spine integrity and dynamics to axonal injury and overall neuronal circuit disruption, ultimately leading to functional and cognitive deficits in both humans and animal models (Nudo, 2013). 
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    Molecular mechanisms of lesion-induced axonal sprouting in the corticofugal projection: the role of glial cells
    Leechung Chang, Nobuhiko Yamamoto
    2023, 18 (6):  1259-1260.  doi: 10.4103/1673-5374.360168
    Abstract ( 92 )   PDF (1175KB) ( 23 )   Save
    After injury of the central nervous system (CNS), neuronal circuits are known to remodel for functional recovery. In general, there are two strategies for the remodeling: axonal regeneration and sprouting (Figure 1A). Axonal regeneration is re-growth of injured neurons themselves, but axons hardly regenerate in the adult mammalian CNS (Silver and Miller, 2004). On the other hand, axonal sprouting is new growth from intact or spared neurons to the denervated target by forming axon collaterals, compensating for damaged circuits. This process is a more effective way for circuit remodeling, as it does not necessarily require long axonal elongation. A well-known example of axonal sprouting is the ectopic projections of the corticofugal projections after unilateral injury of the motor cortex (Figure 1B). Originally, layer 5 neurons in the cortex project ipsilaterally to the midbrain and hindbrain, and contralaterally to the spinal cord. After one side of the cortex is injured, axon sprouting from cortical neurons on the intact side restores connections to the denervated brainstem and spinal cord (Tsukahara, 1981a, b). The elaborate electrophysiological study revealed that ectopic contralateral projections are formed from the intact cortex to the denervated red nucleus in the midbrain, which is involved in the voluntary muscular movement (Tsukahara, 1981a, b). Subsequent studies have further shown that compensatory remodeling occurs in various parts of the CNS, and contributes to functional recovery (Schwab and Strittmatter, 2014). Despite its importance in the recovery, there has been limited progress toward understanding the molecular mechanism of spontaneous axonal sprouting; how the formation of axonal sprouting is coordinated after the injury. Recently, we have demonstrated that factors expressed in the denervated midbrain are involved in the remodeling process, and are produced by glial cells including astrocytes or microglia (Chang et al., 2022). In this perspective, we will briefly present our current understanding of the mechanisms of lesion-induced axonal sprouting of the corticofugal projections, and a view of how glial cells are involved in this process. 
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    Targeting neuroinflammation after therapeutic hypothermia for perinatal hypoxic-ischemic brain injury
    Kelly Q. Zhou, Joanne O. Davidson
    2023, 18 (6):  1261-1262.  doi: 10.4103/1673-5374.360174
    Abstract ( 86 )   PDF (430KB) ( 22 )   Save
    Hypoxic-ischemic encephalopathy (HIE) has an incidence of 1–3 in 1000 term births in high-income countries (Zhou et al., 2020). The standard treatment for these infants is therapeutic hypothermia. Although therapeutic hypothermia significantly reduces the risk of death and disability for infants with HIE, it is still only partially protective as up to 45% of infants still develop disability despite treatment (Zhou et al., 2020). The current therapeutic hypothermia protocol is optimal for widespread use in infants with moderate to severe HIE. However, it is possible that a more tailored approach for individual babies, including stratification of the cooling regimen for the severity of HIE and the identification of reliable biomarkers to guide treatment, may improve efficacy in the future. Current research efforts are now focused on finding add-on treatments to hypothermia that can provide additive neuroprotection (Zhou et al., 2020). This endeavor has proven to be very difficult, as many therapeutic agents have been tested in preclinical and clinical studies, but have shown a lack of additive neuroprotection to therapeutic hypothermia (Zhou et al., 2020). Therefore, a better understanding of the mechanisms of injury that are not targeted by therapeutic hypothermia is needed, in order to find the appropriate add-on treatment that has complementary mechanisms of action.
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    Ketamine, a trauma analgesic with sex-specific immunomodulatory function
    Haley F. Spencer, Rina Y. Berman, Martin Boese, Kwang H. Choi
    2023, 18 (6):  1263-1264.  doi: 10.4103/1673-5374.358617
    Abstract ( 109 )   PDF (345KB) ( 32 )   Save
    Ketamine, a multimodal dissociative anesthetic, produces powerful analgesia at subanesthetic doses in traumatically injured patients. As ketamine does not induce respiratory depression or hemodynamic instability, the Committee on Tactical Combat Casualty Care for the US military recommends the use of subanesthetic doses of ketamine for acute pain management (Butler et al., 2014). Additionally, ketamine may have immunomodulatory effects after injury at subanesthetic doses, mediating the balance of pro- and anti-inflammatory processes (Loix et al., 2011; De Kock et al., 2013). The majority of preclinical studies have examined the immunomodulatory effects of ketamine using only male animals, leaving the issue of sex as a biological variable unanswered. Therefore, in a recent study, we investigated the effects of subanesthetic doses of an intravenous (IV) ketamine infusion (0, 10, and 40 mg/kg, 2 hours) on inflammatory cytokine levels in both male and female Sprague-Dawley rats (Spencer et al., 2022). Using rats with indwelling jugular venous catheters, we were able to measure time-dependent changes in plasma cytokine levels following the IV ketamine infusion. This is a significant contribution to the scientific community due to the growing interest in how sex-related differences may play a role in immune function. Moreover, we tested IV ketamine in a non-inflammatory condition, which has not been well characterized previously. Due to the basal immune response differences between males and females (Klein and Flanagan, 2016), examining ketamine effects in a non-inflammatory condition lays the groundwork for future studies utilizing injured or inflammatory conditions with ketamine administration in male and female animals. 
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    Neural regeneration research model to be explored: SH-SY5Y human neuroblastoma cells
    Lavynia Ferreira Hoffmann, Alexandre Martins, Fernanda Majolo, Verônica Contini, Stefan Laufer, Márcia Inês Goettert
    2023, 18 (6):  1265-1266.  doi: 10.4103/1673-5374.358621
    Abstract ( 175 )   PDF (401KB) ( 143 )   Save
    In neuroscience research, neuronal models are crucial tools for elucidating the molecular and cellular processes involved in the disorders of the nervous system. Facilitating easily and reproducibly executable studies, in vitro models, such as the SH-SY5Y cell line culture, help us explore the pathophysiological mechanisms of neurodegenerative diseases; they are also essential for the efficient screening of drugs for treating the diseases of the nervous system (Peng et al., 2021; Strother et al., 2021).
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    cGMP signaling: a potential therapeutic target for neurodegeneration in glaucoma?
    Joseph M. Holden, Lauren K. Wareham
    2023, 18 (6):  1267-1268.  doi: 10.4103/1673-5374.360169
    Abstract ( 112 )   PDF (742KB) ( 42 )   Save
    Neurodegeneration of the central nervous system (CNS) underscores many of humanity’s most debilitating diseases, including Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis. Recently, the nitric oxide-guanylate cyclase-cyclic guanosine monophosphate (NO-GC-cGMP) signaling pathway has gained traction as a neuroprotective pathway in the CNS. As an extension of the CNS, the retina is also susceptible to neurodegeneration with age. The most prevalent optic neuropathy is glaucoma, the world’s leading cause of irreversible blindness, predicted to affect more than 112 million people worldwide by 2040 (Calkins, 2021). In glaucoma, vision loss occurs due to the progressive degeneration of retinal ganglion cells (RGCs), the output neurons of the retina, along with their axons which form the optic nerve (Wareham et al., 2022). Degeneration of RGCs leads to a characteristic pattern of scotopic visual field deficiencies that spread from one retinotopic sector to the next (Elze et al., 2015). Visual deficits are linked to increasing age and the sensitivity of RGCs to intraocular pressure  (Calkins, 2021). 
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    Putting PLX5622 into perspective: microglia in central nervous system viral infection
    Alanna G. Spiteri, Nicholas J.C. King
    2023, 18 (6):  1269-1270.  doi: 10.4103/1673-5374.360170
    Abstract ( 126 )   PDF (768KB) ( 77 )   Save
    Elucidating the exact contribution of microglia to central nervous system (CNS) pathology has historically been extremely challenging. These resident parenchymal myeloid cells are considered to have critical roles as frontline responders during pathogen invasion and CNS perturbation. Thus, understanding the precise temporal kinetics of microglial function is central to the evolution of novel therapeutics for disease intervention and/or resolution (Spiteri et al., 2022a). The development of PLX5622, a colony-stimulating factor 1 receptor (CSF-1R) inhibitor typically formulated into a rodent chow for simple oral administration has facilitated exploration of microglial functions in disease (Spangenberg et al., 2019). This molecule is widely used as a microglia-depletion agent, with a 20-fold greater selectivity for CSF-1R than other kinases, greater CNS penetrance and better depletion efficacy than previously developed CSF-1R inhibitors like PLX3397. Moreover, PLX5622 is more effective than other microglia depletion systems, including those using clodronate depletion, or CD11b-HSVTK mice that express the herpes-simplex virus thymidine kinase under the CD11b-promoter (Heppner et al., 2005), or CX3CR1CreER: iDTR mice that express Cre-recombinase under the CX3CR1 promoter and crossed with iDTR animals (Bruttger et al., 2015). These approaches require intracranial injections, bone marrow (BM)-reconstitutions, or administration of ganciclovir or tamoxifen, all of which produce non-physiological effects that may confound data interpretation. However, while PLX5622 has undoubtedly enhanced our understanding of microglia biology, studies investigating the potential off-target or indirect effects of this molecule are few and have focused on circulating blood leukocytes or splenocytes. Moreover, these studies have been confined to major cell subsets due to the limited array of cytometric parameters used, and thus the identification of smaller, equally important immune subsets have not been reported. More recently, ex vivo analysis showed impairment in macrophages and lymphoid subsets 3 weeks post-PLX5622 treatment (Lei et al., 2020). Elucidating the precise impact of this molecule on the periphery is important, particularly if PLX5622 is used to study the role of microglia in diseases where peripheral immune cells demonstrably contribute to disease resolution and/or progression, as seen in viral encephalitis. Indeed, modulation of peripheral immune cell compartments by indirect effects of PLX5622 substantially impeded dissection of the role of microglia in a murine model of West Nile virus (WNV) encephalitis (WNE) (Spiteri et al., 2022b; Figure 1). 
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    Nature can still be the strongest help against aging and neurodegeneration: the sirtuins way
    David Della-Morte, Francesca Pacifici
    2023, 18 (6):  1271-1272.  doi: 10.4103/1673-5374.360173
    Abstract ( 108 )   PDF (453KB) ( 177 )   Save
    Unfortunately, aging is not a reversible phenomenon and the processes of senescence are unavoidable. However, the biological effects of aging may be turned back, and with those, it can be reduced risk of all age-related illnesses, such as cardiovascular diseases, cancer, diabetes, and neurodegenerative diseases, including Alzheimer’s disease (AD), and Parkinson’s diseases (PD). In the latest decades, scientists worldwide therefore have developed several strategies, either natural or pharmacological, to counteract aging phenomena, with the final goal to improve human life expectancy. The main scientific rationale beyond these strategies focuses on the opportunity to reduce chronic low-grade inflammation (inflammaging), the increase in oxidative stress damage, and the impairment in the immune system, all typical mechanisms of senescence (Verdaguer et al., 2012). Then, most innovative anti-aging treatments are mainly based on pharmacological senolytic therapeutics, plasma membrane redox system activators, epigenetic modulators, and stem cell therapies (Verdaguer et al., 2012). More specifically, novel therapies against AD include humanized monoclonal antibodies, such as bapineuzumab and solanezumab, targeting senile plaques (Rygiel, 2016); and those against PD include new pharmaceutical compounds, such as Neu 120, and V1512, EPI-589, targeting neurological central motor system (Zhong et al., 2022). 
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    Neural differentiation protocols: how to choose the correct approach
    Michael Telias
    2023, 18 (6):  1273-1274.  doi: 10.4103/1673-5374.360171
    Abstract ( 106 )   PDF (412KB) ( 33 )   Save
    Pluripotent stem cells in neural differentiation: characterization and potential: The establishment and use of pluripotent stem cells (PSCs), including embryonic (ESCs) and induced (iPSCs), constitutes a major scientific breakthrough of the last decades. Human PSCs hold the potential to deliver regenerative therapies in many diseases, including neurological ones. The general approach is to produce functioning human neurons and glial cells in vitro, to be later implanted in the diseased nervous system, replacing dysfunctional or dead cells. In addition, human and other animal-sourced PSCs make useful and dynamic in vitro models for neurodevelopmental, neurodegenerative and psychiatric disorders, enabling researchers to continuously produce normal and diseased neurons to investigate basic mechanistic questions, which can eventually lead to new therapeutics. Therefore, the development of efficient protocols to induce neural differentiation in ESCs and iPSCs is currently a major effort in the field (Mertens et al., 2016). 
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    Synaptosome microRNAs: emerging synapse players in aging and Alzheimer’s disease
    Subodh Kumar
    2023, 18 (6):  1275-1276.  doi: 10.4103/1673-5374.360172
    Abstract ( 76 )   PDF (1346KB) ( 22 )   Save
    Synaptosome: Synapses are the most critical portion of neuron connections, necessary for cellular organization of the brain. Synapse integrity is uttermost important for healthy brain functioning. Any perturbation in the synapse structure and/or function initiates neurological disorders. Synapses are the prime targets that are smashed in almost all neurodegenerative diseases. The vital components of synapse are essential for neurotransmission, synaptic plasticity and overall synapse function. Synapse dysfunctions are well studied in Alzheimer’s disease (AD) and other neurodegenerative diseases (Gowda et al., 2021). The best way to study the synapse dysfunctions in neurological diseases is the biochemical analysis of “synaptosome”. Researchers studied the synaptosome to understand the molecular reasons of synapse dysfunction in aging, AD and other neurodegenerative diseases (Kumar et al., 2020; Gowda et al., 2021). Synaptosome maintains the cellular machinery and all vital components necessary for autonomous synapse function. Synaptosome retains mitochondria, synaptic vesicles, lysosomes, endosomes along with the postsynaptic membrane and the postsynaptic density (Lugli et al., 2012; Xu et al., 2013; Li et al., 2015; Kumar et al., 2020). Therefore, synaptosomes hold the molecular machinery necessary for uptake, storage, and release of neurotransmitters, channels, receptors, and local signal transduction. Based on these properties, synaptosomes are called as “Ex vivo” model to study synaptic physiology and pathophysiology. They also pronounced as “halfway house” between neurochemistry and electrophysiology (Lugli et al., 2012; Xu et al., 2013; Li et al., 2015; Kumar et al., 2020). However, there are some technical difficulties while studying the synaptosome. Due to synapse degradation and/or reduced synapse numbers in AD, we need the large amount of brain tissue (≥ 50 mg) to isolate the appropriate quantity of synaptosome for electron microscopy, mRNA and protein analysis. Another technical challenge is mitochondria contamination in synaptosome fraction because of the overlapping size of synaptosome (0.6 to 1 μm) and mitochondria (0.5 to 3 μm). Though mitochondria are a part of synaptosome, but sometimes we observed the separate mitochondrial contamination while preparing the synaptosomes. We can avoid the mitochondria contamination by applying the soft and gentle Dounce homogenization for synaptosome extraction (Kumar et al., 2022).  
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    Neuronal nitric oxide synthase/reactive oxygen species pathway is involved in apoptosis and pyroptosis in epilepsy
    Xiao-Xue Xu, Rui-Xue Shi, Yu Fu, Jia-Lu Wang, Xin Tong, Shi-Qi Zhang, Na Wang, Mei-Xuan Li, Yu Tong, Wei Wang, Miao He, Bing-Yang Liu, Gui-Lan Chen, Feng Guo
    2023, 18 (6):  1277-1285.  doi: 10.4103/1673-5374.357906
    Abstract ( 346 )   PDF (29546KB) ( 71 )   Save
    Dysfunction of neuronal nitric oxide synthase contributes to neurotoxicity, which triggers cell death in various neuropathological diseases, including epilepsy. Studies have shown that inhibition of neuronal nitric oxide synthase activity increases the epilepsy threshold, that is, has an anticonvulsant effect. However, the exact role and potential mechanism of neuronal nitric oxide synthase in seizures are still unclear. In this study, we performed RNA sequencing, functional enrichment analysis, and weighted gene coexpression network analysis of the hippocampus of tremor rats, a rat model of genetic epilepsy. We found damaged hippocampal mitochondria and abnormal succinate dehydrogenase level and Na+-K+-ATPase activity. In addition, we used a pilocarpine-induced N2a cell model to mimic epileptic injury. After application of neuronal nitric oxide synthase inhibitor 7-nitroindazole, changes in malondialdehyde, lactate dehydrogenase and superoxide dismutase, which are associated with oxidative stress, were reversed, and the increase in reactive oxygen species level was reversed by 7-nitroindazole or reactive oxygen species inhibitor N-acetylcysteine. Application of 7-nitroindazole or N-acetylcysteine downregulated the expression of caspase-3 and cytochrome c and reversed the apoptosis of epileptic cells. Furthermore, 7-nitroindazole or N-acetylcysteine downregulated the abnormally high expression of NLRP3, gasdermin-D, interleukin-1β and interleukin-18. This indicated that 7-nitroindazole and N-acetylcysteine each reversed epileptic cell death. Taken together, our findings suggest that the neuronal nitric oxide synthase/reactive oxygen species pathway is involved in pyroptosis of epileptic cells, and inhibiting neuronal nitric oxide synthase activity or its induced oxidative stress may play a neuroprotective role in epilepsy.
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    Overexpression of vascular endothelial growth factor enhances the neuroprotective effects of bone marrow mesenchymal stem cell transplantation in ischemic stroke
    Cui Liu, Zhi-Xiang Yang, Si-Qi Zhou, Ding Ding, Yu-Ting Hu, Hong-Ning Yang, Dong Han, Shu-Qun Hu, Xue-Mei Zong
    2023, 18 (6):  1286-1292.  doi: 10.4103/1673-5374.358609
    Abstract ( 151 )   PDF (5150KB) ( 73 )   Save
    Although bone marrow mesenchymal stem cells (BMSCs) might have therapeutic potency in ischemic stroke, the benefits are limited. The current study investigated the effects of BMSCs engineered to overexpress vascular endothelial growth factor (VEGF) on behavioral defects in a rat model of transient cerebral ischemia, which was induced by middle cerebral artery occlusion. VEGF-BMSCs or control grafts were injected into the left striatum of the infarcted hemisphere 24 hours after stroke. We found that compared with the stroke-only group and the vehicle- and BMSCs-control groups, the VEGF-BMSCs treated animals displayed the largest benefits, as evidenced by attenuated behavioral defects and smaller infarct volume 7 days after stroke. Additionally, VEGF-BMSCs greatly inhibited destruction of the blood-brain barrier, increased the regeneration of blood vessels in the region of ischemic penumbra, and reducedneuronal degeneration surrounding the infarct core. Further mechanistic studies showed that among all transplant groups, VEGF-BMSCs transplantation induced the highest level of brain-derived neurotrophic factor. These results suggest that BMSCs transplantation with vascular endothelial growth factor has the potential to treat ischemic stroke with better results than are currently available. 
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    Treadmill exercise exerts a synergistic effect with bone marrow mesenchymal stem cell-derived exosomes on neuronal apoptosis and synaptic-axonal remodeling 
    Xin-Hong Jiang, Hang-Feng Li, Man-Li Chen, Yi-Xian Zhang, Hong-Bin Chen, Rong-Hua Chen, Ying-Chun Xiao, Nan Liu
    2023, 18 (6):  1293-1299.  doi: 10.4103/1673-5374.357900
    Abstract ( 127 )   PDF (10735KB) ( 63 )   Save
    Treadmill exercise and mesenchymal stem cell transplantation are both practical and effective methods for the treatment of cerebral ischemia. However, whether there is a synergistic effect between the two remains unclear. In this study, we established rat models of ischemia/reperfusion injury by occlusion of the middle cerebral artery for 2 hours and reperfusion for 24 hours. Rat models were perfused with bone marrow mesenchymal stem cell-derived exosomes (MSC-exos) via the tail vein and underwent 14 successive days of treadmill exercise. Neurological assessment, histopathology, and immunohistochemistry results revealed decreased neuronal apoptosis and cerebral infarct volume, evident synaptic formation and axonal regeneration, and remarkably recovered neurological function in rats subjected to treadmill exercise and MSC-exos treatment. These effects were superior to those in rats subjected to treadmill exercise or MSC-exos treatment alone. Mechanistically, further investigation revealed that the activation of JNK1/c-Jun signaling pathways regulated neuronal apoptosis and synaptic-axonal remodeling. These findings suggest that treadmill exercise may exhibit a synergistic effect with MSC-exos treatment, which may be related to activation of the JNK1/c-Jun signaling pathway. This study provides novel theoretical evidence for the clinical application of treadmill exercise combined with MSC-exos treatment for ischemic cerebrovascular disease. 
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    The relationship among amyloid-β deposition, sphingomyelin level, and the expression and function of P-glycoprotein in Alzheimer’s disease pathological process
    Zi-Kang Xing, Li-Sha Du, Xin Fang, Heng Liang, Sheng-Nan Zhang, Lei Shi, Chun-Xiang Kuang, Tian-Xiong Han, Qing Yang
    2023, 18 (6):  1300-1307.  doi: 10.4103/1673-5374.358607
    Abstract ( 166 )   PDF (4471KB) ( 149 )   Save
    In Alzheimer’s disease, the transporter P-glycoprotein is responsible for the clearance of amyloid-β in the brain. Amyloid-β correlates with the sphingomyelin metabolism, and sphingomyelin participates in the regulation of P-glycoprotein. The amyloid cascade hypothesis describes amyloid-β as the central cause of Alzheimer’s disease neuropathology. Better understanding of the change of P-glycoprotein and sphingomyelin along with amyloid-β and their potential association in the pathological process of Alzheimer’s disease is critical. Herein, we found that the expression of P-glycoprotein in APP/PS1 mice tended to increase with age and was significantly higher at 9 and 12 months of age than that in wild-type mice at comparable age. The functionality of P-glycoprotein of APP/PS1 mice did not change with age but was significantly lower than that of wild-type mice at 12 months of age. Decreased sphingomyelin levels, increased ceramide levels, and the increased expression and activity of neutral sphingomyelinase 1 were observed in APP/PS1 mice at 9 and 12 months of age compared with the levels in wild-type mice. Similar results were observed in the Alzheimer’s disease mouse model induced by intracerebroventricular injection of amyloid-β1–42 and human cerebral microvascular endothelial cells treated with amyloid-β1–42. In human cerebral microvascular endothelial cells, neutral sphingomyelinase 1 inhibitor interfered with the changes of sphingomyelin metabolism and P-glycoprotein expression and functionality caused by amyloid-β1–42 treatment. Neutral sphingomyelinase 1 regulated the expression and functionality of P-glycoprotein and the levels of sphingomyelin and ceramide. Together, these findings indicate that neutral sphingomyelinase 1 regulates the expression and function of P-glycoprotein via the sphingomyelin/ceramide pathway. These studies may serve as new pursuits for the development of anti-Alzheimer’s disease drugs.
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    Withaferin A inhibits ferroptosis and protects against intracerebral hemorrhage
    Zi-Xian Zhou, Qi Cui, Ying-Mei Zhang, Jia-Xin Yang, Wen-Jing Xiang, Ning Tian, Yan-Lin Jiang, Mei-Ling Chen, Bin Yang, Qing-Hua Li, Ru-Jia Liao
    2023, 18 (6):  1308-1315.  doi: 10.4103/1673-5374.355822
    Abstract ( 179 )   PDF (6427KB) ( 175 )   Save
    Recent studies have indicated that suppressing oxidative stress and ferroptosis can considerably improve the prognosis of intracerebral hemorrhage (ICH). Withaferin A (WFA), a natural compound, exhibits a positive effect on a number of neurological diseases. However, the effects of WFA on oxidative stress and ferroptosis-mediated signaling pathways to ICH remain unknown. In this study, we investigated the neuroprotective effects and underlying mechanism for WFA in the regulation of ICH-induced oxidative stress and ferroptosis. We established a mouse model of ICH by injection of autologous tail artery blood into the caudate nucleus and an in vitro cell model of hemin-induced ICH. WFA was injected intracerebroventricularly at 0.1, 1 or 5 μg/kg once daily for 7 days, starting immediately after ICH operation. WFA markedly reduced brain tissue injury and iron deposition and improved neurological function in a dose-dependent manner 7 days after cerebral hemorrhage. Through in vitro experiments, cell viability test showed that WFA protected SH-SY5Y neuronal cells against hemin-induced cell injury. Enzyme-linked immunosorbent assays in vitro and in vivo showed that WFA markedly decreased the level of malondialdehyde, an oxidative stress marker, and increased the activities of anti-oxidative stress markers superoxide dismutase and glutathione peroxidase after ICH. Western blot assay, quantitative polymerase chain reaction and immunofluorescence results demonstrated that WFA activated the nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling axis, promoted translocation of Nrf2 from the cytoplasm to nucleus, and increased HO-1 expression. Silencing Nrf2 with siRNA completely reversed HO-1 expression, oxidative stress and protective effects of WFA. Furthermore, WFA reduced hemin-induced ferroptosis. However, after treatment with an HO-1 inhibitor, the neuroprotective effects of WFA against hemin-induced ferroptosis were weakened. MTT test results showed that WFA combined with ferrostatin-1 reduced hemin-induced SH-SY5Y neuronal cell injury. Our findings reveal that WFA treatment alleviated ICH injury-induced ferroptosis and oxidative stress through activating the Nrf2/HO-1 pathway, which may highlight a potential role of WFA for the treatment of ICH. 
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    Exosome-transported lncRNA H19 regulates insulin-like growth factor-1 via the H19/let-7a/insulin-like growth factor-1 receptor axis in ischemic stroke
    Jue Wang, Bin Cao, Yan Gao, Yu-Hua Chen, Juan Feng
    2023, 18 (6):  1316-1320.  doi: 10.4103/1673-5374.357901
    Abstract ( 110 )   PDF (1809KB) ( 51 )   Save
    LncRNA (long non-coding RNA) H19 is a transcript of the H19 gene that is expressed during embryogenesis. We previously discovered a role for circular lncRNA H19 in the onset and prognosis of cerebral ischemic stroke. In this study, we used serum from patients with ischemic stroke, and mouse and cell culture models to elucidate the roles of plasma and neuronal exosomes in the regulatory effect of lncRNA H19 on insulin-like growth factor-1 and its mechanism in ischemic stroke, using western blotting, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assays. Plasma exosomal lncRNA H19 was negatively associated with blood levels of insulin-like growth factor-1 in samples from patients with cerebral ischemic stroke. In a mouse model, levels of exosomal lncRNA H19 were positively correlated with plasma and cerebral lncRNA H19. In a cell co-culture model, we confirmed that lncRNA H19 was transported from neurons to astrocytes by exosomes to induce downregulation of insulin-like growth factor-1 through the H19/let-7a/insulin-like growth factor-1 receptor axis. This study provides the first evidence for the transportation of lncRNA H19 by exosomes and the relationship between lncRNA H19 and insulin-like growth factor-1. 
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    A molecular probe carrying anti-tropomyosin 4 for early diagnosis of cerebral ischemia/reperfusion injury
    Teng-Fei Yu, Kun Wang, Lu Yin, Wen-Zhe Li, Chuan-Ping Li, Wei Zhang, Jie Tian, Wen He
    2023, 18 (6):  1321-1324.  doi: 10.4103/1673-5374.357907
    Abstract ( 111 )   PDF (61445KB) ( 59 )   Save
    In vivo imaging of cerebral ischemia/reperfusion injury remains an important challenge. We injected porous Ag/Au@SiO2 bimetallic hollow nanoshells carrying anti-tropomyosin 4 as a molecular probe into mice with cerebral ischemia/reperfusion injury and observed microvascular changes in the brain using photoacoustic imaging with ultrasonography. At each measured time point, the total photoacoustic signal was significantly higher on the affected side than on the healthy side. Twelve hours after reperfusion, cerebral perfusion on the affected side increased, cerebrovascular injury worsened, and anti-tropomyosin 4 expression increased. Twenty-four hours after reperfusion and later, perfusion on the affected side declined slowly and stabilized after 1 week; brain injury was also alleviated. Histopathological and immunohistochemical examinations confirmed the brain injury tissue changes. The nanoshell molecular probe carrying anti-tropomyosin 4 has potential for use in early diagnosis of cerebral ischemia/reperfusion injury and evaluating its progression. 
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    Microglial depletion impairs glial scar formation and aggravates inflammation partly by inhibiting STAT3 phosphorylation in astrocytes after spinal cord injury
    Zhi-Lai Zhou, Huan Xie, Xiao-Bo Tian, Hua-Li Xu, Wei Li, Shun Yao, Hui Zhang
    2023, 18 (6):  1325-1331.  doi: 10.4103/1673-5374.357912
    Abstract ( 208 )   PDF (2863KB) ( 158 )   Save
    Astrocytes and microglia play an orchestrated role following spinal cord injury; however, the molecular mechanisms through which microglia regulate astrocytes after spinal cord injury are not yet fully understood. Herein, microglia were pharmacologically depleted and the effects on the astrocytic response were examined. We further explored the potential mechanisms involving the signal transducers and activators of transcription 3 (STAT3) pathway. For in vivo experiments, we constructed a contusion spinal cord injury model in C57BL/6 mice. To deplete microglia, all mice were treated with colony-stimulating factor 1 receptor inhibitor PLX3397, starting 2 weeks prior to surgery until they were sacrificed. Cell proliferation was examined by 5-ethynyl-2-deoxyuridine (EdU) and three pivotal inflammatory cytokines were detected by a specific Bio-Plex ProTM Reagent Kit. Locomotor function, neuroinflammation, astrocyte activation and phosphorylated STAT3 (pSTAT3, a maker of activation of STAT3 signaling) levels were determined. For in vitro experiments, a microglia and astrocyte coculture system was established, and the small molecule STA21, which blocks STAT3 activation, was applied to investigate whether STAT3 signaling is involved in mediating astrocyte proliferation induced by microglia. PLX3397 administration disrupted glial scar formation, increased inflammatory spillover, induced diffuse tissue damage and impaired functional recovery after spinal cord injury. Microglial depletion markedly reduced EdU+ proliferating cells, especially proliferating astrocytes at 7 days after spinal cord injury. RNA sequencing analysis showed that the JAK/STAT3 pathway was downregulated in mice treated with PLX3397. Double immunofluorescence staining confirmed that PLX3397 significantly decreased STAT3 expression in astrocytes. Importantly, in vitro coculture of astrocytes and microglia showed that microglia-induced astrocyte proliferation was abolished by STA21 administration. These findings suggest that microglial depletion impaired astrocyte proliferation and astrocytic scar formation, and induced inflammatory diffusion partly by inhibiting STAT3 phosphorylation in astrocytes following spinal cord injury.
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    Ginsenoside Rb1 improves energy metabolism after spinal cord injury
    Shan Wen, Zhi-Ru Zou, Shuai Cheng, Hui Guo, Heng-Shuo Hu, Fan-Zhuo Zeng, Xi-Fan Mei
    2023, 18 (6):  1332-1338.  doi: 10.4103/1673-5374.357915
    Abstract ( 214 )   PDF (5330KB) ( 128 )   Save
    Mitochondrial damage caused by oxidative stress and energy deficiency induced by focal ischemia and hypoxia are important factors that aggravate diseases. Studies have shown that ginsenoside Rb1 has neurotrophic and neuroprotective effects. However, whether it influences energy metabolism after spinal cord injury remains unclear. In this study, we treated mouse and cell models of spinal cord injury with ginsenoside Rb1. We found that ginsenoside Rb1 remarkably inhibited neuronal oxidative stress, protected mitochondria, promoted neuronal metabolic reprogramming, increased glycolytic activity and ATP production, and promoted the survival of motor neurons in the anterior horn and the recovery of motor function in the hind limb. Because sirtuin 3 regulates glycolysis and oxidative stress, mouse and cell models of spinal cord injury were treated with the sirtuin 3 inhibitor 3-TYP. When Sirt3 expression was suppressed, we found that the therapeutic effects of ginsenoside Rb1 on spinal cord injury were remarkably inhibited. Therefore, ginsenoside Rb1 is considered a potential drug for the treatment of spinal cord injury, and its therapeutic effects are closely related to sirtuin 3. 
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    Thrombin increases the expression of cholesterol 25-hydroxylase in rat astrocytes after spinal cord injury
    Chen Chen, Huiyuan Ji, Nan Jiang, Yingjie Wang, Yue Zhou, Zhenjie Zhu, Yuming Hu, Yongjun Wang, Aihong Li, Aisong Guo
    2023, 18 (6):  1339-1346.  doi: 10.4103/1673-5374.357905
    Abstract ( 174 )   PDF (7118KB) ( 54 )   Save
    Astrocytes are important cellular centers of cholesterol synthesis and metabolism that help maintain normal physiological function at the organism level. Spinal cord injury results in aberrant cholesterol metabolism by astrocytes and excessive production of oxysterols, which have profound effects on neuropathology. 25-Hydroxycholesterol (25-HC), the main product of the membrane-associated enzyme cholesterol-25-hydroxylase (CH25H), plays important roles in mediating neuroinflammation. However, whether the abnormal astrocyte cholesterol metabolism induced by spinal cord injury contributes to the production of 25-HC, as well as the resulting pathological effects, remain unclear. In the present study, spinal cord injury-induced activation of thrombin was found to increase astrocyte CH25H expression. A protease-activated receptor 1 inhibitor was able to attenuate this effect in vitro and in vivo. In cultured primary astrocytes, thrombin interacted with protease-activated receptor 1, mainly through activation of the mitogen-activated protein kinase/nuclear factor-kappa B signaling pathway. Conditioned culture medium from astrocytes in which ch25h expression had been knocked down by siRNA reduced macrophage migration. Finally, injection of the protease activated receptor 1 inhibitor SCH79797 into rat neural sheaths following spinal cord injury reduced migration of microglia/macrophages to the injured site and largely restored motor function. Our results demonstrate a novel regulatory mechanism for thrombin-regulated cholesterol metabolism in astrocytes that could be used to develop anti-inflammatory drugs to treat patients with spinal cord injury.
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    Overexpression of fibroblast growth factor 13 ameliorates amyloid-β-induced neuronal damage
    Ruo-Meng Li, Lan Xiao, Ting Zhang, Dan Ren, Hong Zhu
    2023, 18 (6):  1347-1353.  doi: 10.4103/1673-5374.357902
    Abstract ( 112 )   PDF (2476KB) ( 106 )   Save
    Previous studies have shown that fibroblast growth factor 13 is downregulated in the brain of both Alzheimer’s disease mouse models and patients, and that it plays a vital role in the learning and memory. However, the underlying mechanisms of fibroblast growth factor 13 in Alzheimer’s disease remain unclear. In this study, we established rat models of Alzheimer’s disease by stereotaxic injection of amyloid-β (Aβ1–42)-induced into bilateral hippocampus. We also injected lentivirus containing fibroblast growth factor 13 into bilateral hippocampus to overexpress fibroblast growth factor 13. The expression of fibroblast growth factor 13 was downregulated in the brain of the Alzheimer’s disease model rats. After overexpression of fibroblast growth factor 13, learning and memory abilities of the Alzheimer’s disease model rats were remarkably improved. Fibroblast growth factor 13 overexpression increased brain expression levels of oxidative stress-related markers glutathione, superoxide dismutase, phosphatidylinositol-3-kinase, AKT and glycogen synthase kinase 3β, and anti-apoptotic factor BCL. Furthermore, fibroblast growth factor 13 overexpression decreased the number of apoptotic cells, expression of pro-apoptotic factor BAX, cleaved-caspase 3 and amyloid-β expression, and levels of tau phosphorylation, malondialdehyde, reactive oxygen species and acetylcholinesterase in the brain of Alzheimer’s disease model rats. The changes were reversed by the phosphatidylinositol-3-kinase inhibitor LY294002. These findings suggest that overexpression of fibroblast growth factor 13 improved neuronal damage in a rat model of Alzheimer’s disease through activation of the phosphatidylinositol-3-kinase/AKT/glycogen synthase kinase 3β signaling pathway.
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    Charcot-Marie-Tooth-1A and sciatic nerve crush rat models: insights from proteomics
    Zeina Msheik, Stephanie Durand, Emilie Pinault, Martial Caillaud, Laetitia Vignaud, Fabrice Billet, Mohamed El Massry, Alexis Desmouliere
    2023, 18 (6):  1354-1363.  doi: 10.4103/1673-5374.357911
    Abstract ( 103 )   PDF (7772KB) ( 53 )   Save
    The sensorimotor and histological aspects of peripheral neuropathies were already studied by our team in two rat models: the sciatic nerve crush and the Charcot-Marie-Tooth-1A disease. In this study, we sought to highlight and compare the protein signature of these two pathological situations. Indeed, the identification of protein profiles in diseases can play an important role in the development of pharmacological targets. In fact, Charcot-Marie-Tooth-1A rats develop motor impairments that are more severe in the hind limbs. Therefore, for the first time, protein expression in sciatic nerve of Charcot-Marie-Tooth-1A rats was examined. First, distal sciatic nerves were collected from Charcot-Marie-Tooth-1A and uninjured wild-type rats aged 3 months. After protein extraction, sequential window acquisition of all theoretical fragment ion spectra liquid chromatography and mass spectrometry was employed. 445 proteins mapped to Swiss-Prot or trEMBL Uniprot databases were identified and quantified. Of these, 153 proteins showed statistically significant differences between Charcot-Marie-Tooth-1A and wild-type groups. The majority of these proteins were overexpressed in Charcot-Marie-Tooth-1A. Hierarchical clustering and functional enrichment using Gene Ontology were used to group these proteins based on their biological effects concerning Charcot-Marie-Tooth-1A pathophysiology. Second, proteomic characterization of wild-type rats subjected to sciatic nerve crush was performed sequential window acquisition of all theoretical fragment ion spectra liquid chromatography and mass spectrometry. One month after injury, distal sciatic nerves were collected and analyzed as described above. Out of 459 identified proteins, 92 showed significant differences between sciatic nerve crush and the uninjured wild-type rats used in the first study. The results suggest that young adult Charcot-Marie-Tooth-1A rats (3 months old) develop compensatory mechanisms at the level of redox balance, protein folding, myelination, and axonogenesis. These mechanisms seem insufficient to hurdle the progress of the disease. Notably, response to oxidative stress appears to be a significant feature of Charcot-Marie-Tooth-1A, potentially playing a role in the pathological process. In contrast to the first experiment, the majority of the proteins that differed from wild-type were downregulated in the sciatic nerve crush group. Functional enrichment suggested that neurogenesis, response to axon injury, and oxidative stress were important biological processes. Protein analysis revealed an imperfect repair at this time point after injury and identified several distinguishable proteins. In conclusion, we suggest that peripheral neuropathies, whether of a genetic or traumatic cause, share some common pathological pathways. This study may provide directions for better characterization of these models and/or identifying new specific therapeutic targets.
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    Glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor regulate the interaction between astrocytes and Schwann cells at the trigeminal root entry zone
    Madeha Ishag Adam, Ling Lin, Amir Mahmoud Makin, Xiao-Fen Zhang, Lu-Xi Zhou, Xin-Yue Liao, Li Zhao, Feng Wang, Dao-Shu Luo
    2023, 18 (6):  1364-1370.  doi: 10.4103/1673-5374.354517
    Abstract ( 213 )   PDF (9375KB) ( 172 )   Save
    The trigeminal root entry zone is the zone at which the myelination switches from peripheral Schwann cells to central oligodendrocytes. Its special anatomical and physiological structure renders it susceptible to nerve injury. The etiology of most primary trigeminal neuralgia is closely related to microvascular compression of the trigeminal root entry zone. This study aimed to develop an efficient in vitro model mimicking the glial environment of trigeminal root entry zone as a tool to investigate the effects of glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor on the structural and functional integrity of trigeminal root entry zone and modulation of cellular interactions. Primary astrocytes and Schwann cells isolated from trigeminal root entry zone of postnatal rats were inoculated into a two-well silicon culture insert to mimic the trigeminal root entry zone microenvironment and treated with glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor. In monoculture, glial cell line-derived neurotrophic factor promoted the migration of Schwann cells, but it did not have effects on the migration of astrocytes. In the co-culture system, glial cell line-derived neurotrophic factor promoted the bidirectional migration of astrocytes and Schwann cells. Brain-derived neurotrophic factor markedly promoted the activation and migration of astrocytes. However, in the co-culture system, brain-derived neurotrophic factor inhibited the migration of astrocytes and Schwann cells to a certain degree. These findings suggest that glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor are involved in the regulation of the astrocyte-Schwann cell interaction in the co-culture system derived from the trigeminal root entry zone. This system can be used as a cell model to study the mechanism of glial dysregulation associated with trigeminal nerve injury and possible therapeutic interventions. 
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    Argon preconditioning protects neuronal cells with a Toll-like receptor-mediated effect
    Stefanie Scheid, Adrien Lejarre, Jakob Wollborn, Hartmut Buerkle, Ulrich Goebel, Felix Ulbrich
    2023, 18 (6):  1371-1377.  doi: 10.4103/1673-5374.355978
    Abstract ( 129 )   PDF (4115KB) ( 59 )   Save
    The noble gas argon has the potential to protect neuronal cells from cell death. So far, this effect has been studied in treatment after acute damage. Preconditioning using argon has not yet been investigated. In this study, human neuroblastoma SH-SY5Y cells were treated with different concentrations of argon (25%, 50%, and 74%; 21% O2, 5% CO2, balance nitrogen) at different time intervals before inflicting damage with rotenone (20 µM, 4 hours). Apoptosis was determined by flow cytometry after annexin V and propidium iodide staining. Surface expressions of Toll-like receptors 2 and 4 were also examined. Cells were also processed for analysis by western blot and qPCR to determine the expression of apoptotic and inflammatory proteins, such as extracellular-signal regulated kinase (ERK1/2), nuclear transcription factor-κB (NF-κB), protein kinase B (Akt), caspase-3, Bax, Bcl-2, interleukin-8, and heat shock proteins. Immunohistochemical staining was performed for TLR2 and 4 and interleukin-8. Cells were also pretreated with OxPAPC, an antagonist of TLR2 and 4 to elucidate the molecular mechanism. Results showed that argon preconditioning before rotenone application caused a dose-dependent but not a time-dependent reduction in the number of apoptotic cells. Preconditioning with 74% argon for 2 hours was used for further experiments showing the most promising results. Argon decreased the surface expression of TLR2 and 4, whereas OxPAPC treatment partially abolished the protective effect of argon. Argon increased phosphorylation of ERK1/2 but decreased NF-κB and Akt. Preconditioning inhibited mitochondrial apoptosis and the heat shock response. Argon also suppressed the expression of the pro-inflammatory cytokine interleukin-8. Immunohistochemistry confirmed the alteration of TLRs and interleukin-8. OxPAPC reversed the argon effect on ERK1/2, Bax, Bcl-2, caspase-3, and interleukin-8 expression, but not on NF-κB and the heat shock proteins. Taken together, argon preconditioning protects against apoptosis of neuronal cells and mediates its action via Toll-like receptors. Argon may represent a promising therapeutic alternative in various clinical settings, such as the treatment of stroke.
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    Chitosan conduits enriched with fibrin-collagen hydrogel with or without adipose-derived mesenchymal stem cells for the repair of 15-mm-long sciatic nerve defect
    Marwa El Soury, Óscar Darío García-García, Isabella Tarulli, Jesús Chato-Astrain, Isabelle Perroteau, Stefano Geuna, Stefania Raimondo, Giovanna Gambarotta, Víctor Carriel
    2023, 18 (6):  1378-1385.  doi: 10.4103/1673-5374.358605
    Abstract ( 113 )   PDF (5290KB) ( 47 )   Save
    Hollow conduits of natural or synthetic origins have shown acceptable regeneration results in short nerve gap repair; however, results are still not comparable with the current gold standard technique “autografts”. Hollow conduits do not provide a successful regeneration outcome when it comes to critical nerve gap repair. Enriching the lumen of conduits with different extracellular materials and cells could provide a better biomimicry of the natural nerve regenerating environment and is expected to ameliorate the conduit performance. In this study, we evaluated nerve regeneration in vivo using hollow chitosan conduits or conduits enriched with fibrin-collagen hydrogels alone or with the further addition of adipose-derived mesenchymal stem cells in a 15 mm rat sciatic nerve transection model. Unexpected changes in the hydrogel consistency and structural stability in vivo led to a failure of nerve regeneration after 15 weeks. Nevertheless, the molecular assessment in the early regeneration phase (7, 14, and 28 days) has shown an upregulation of useful regenerative genes in hydrogel enriched conduits compared with the hollow ones. Hydrogels composed of fibrin-collagen were able to upregulate the expression of soluble NRG1, a growth factor that plays an important role in Schwann cell transdifferentiation. The further enrichment with adipose-derived mesenchymal stem cells has led to the upregulation of other important genes such as ErbB2, VEGF-A, BDNF, c-Jun, and ATF3. 
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    The role of crm-1 in ionizing radiation-induced nervous system dysfunction in Caenorhabditis elegans
    Hui-Qiang Long, Jin Gao, Shu-Qing He, Jian-Fang Han, Yu Tu, Na Chen
    2023, 18 (6):  1386-1392.  doi: 10.4103/1673-5374.357908
    Abstract ( 127 )   PDF (3022KB) ( 64 )   Save
    Ionizing radiation can cause changes in nervous system function. However, the underlying mechanism remains unclear. In this study, Caenorhabditis elegans (C. elegans) was irradiated with 75 Gy of 60Co whole-body γ radiation. Behavioral indicators (head thrashes, touch avoidance, and foraging), and the development of dopaminergic neurons related to behavioral function, were evaluated to assess the effects of ionizing radiation on nervous system function in C. elegans. Various behaviors were impaired after whole-body irradiation and degeneration of dopamine neurons was observed. This suggests that 75 Gy of γ radiation is sufficient to induce nervous system dysfunction. The genes nhr-76 and crm-1, which are reported to be related to nervous system function in human and mouse, were screened by transcriptome sequencing and bioinformatics analysis after irradiation or sham irradiation. The expression levels of these two genes were increased after radiation. Next, RNAi technology was used to inhibit the expression of crm-1, a gene whose homologs are associated with motor neuron development in other species. Downregulation of crm-1 expression effectively alleviated the deleterious effects of ionizing radiation on head thrashes and touch avoidance. It was also found that the expression level of crm-1 was regulated by the nuclear receptor gene nhr-76. The results of this study suggest that knocking down the expression level of nhr-76 can reduce the expression level of crm-1, while down-regulating the expression level of crm-1 can alleviate behavioral disorders induced by ionizing radiation. Therefore, inhibition of crm-1 may be of interest as a potential therapeutic target for ionizing radiation-induced neurological dysfunction. 
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