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    15 July 2024, Volume 19 Issue 7 Previous Issue    Next Issue
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    New insights into the role of the endoplasmic reticulum in microglia
    Veronika E. Neubrand, M. Rosario Sepúlveda
    2024, 19 (7):  1397-1398.  doi: 10.4103/1673-5374.387981
    Abstract ( 210 )   PDF (902KB) ( 92 )   Save
    Microglial cells are the only resident immune cells in the central nervous system and constitute its frontline guardian. They are extremely reactive against infections, trauma, or toxins, but are also responsible for mediating inflammation, taking part in the pathogenic course of many neuropathologies (Sierra et al., 2019). Cell-specific staining, ultrastructural analysis by transmission electron microscopy (TEM), or two-photon-microscopy imaging have been relevant for the characterization of microglia as well as their cell-cell interactions, which have led to a better understanding of microglial roles in health and disease.
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    Neural membrane repair at the core of regeneration
    Catarina Dias, Jesper Nylandsted
    2024, 19 (7):  1399-1400.  doi: 10.4103/1673-5374.386408
    Abstract ( 143 )   PDF (513KB) ( 65 )   Save
    Loss of plasma membrane integrity can compromise cell functioning and viability. To counteract this eminent threat, eukaryotic cells have developed efficient repair mechanisms, which seem to have co-evolved with the emergence of vital membrane processes (Cooper and McNeil, 2015). This relationship between basic cellular functioning and membrane repair highlights the fundamental significance of preserving membrane integrity for cellular life.
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    Mitochondrial recruitment in myelin: an anchor for myelin dynamics and plasticity?
    Jean-David M. Gothié, Timothy E. Kennedy
    2024, 19 (7):  1401-1402.  doi: 10.4103/1673-5374.387982
    Abstract ( 145 )   PDF (842KB) ( 46 )   Save
    Optimal propagation of neuronal electrical impulses depends on the insulation of axons by myelin, produced in the central nervous system by oligodendrocytes. Myelin is an extension of the oligodendrocyte plasma membrane, which wraps around an axon to form a compact multi-layered sheath. Myelin is composed of a substantially higher proportion of lipids compared to other biological membranes and enriched in a small number of specialized proteins. Myelin internodes are plastic, with the capacity to make relatively subtle changes in thickness, elongate or retract, or more dramatically add or delete segments, in response to stimuli such as neuronal activity or memory formation, and during maturation and aging (de Faria et al., 2021). For myelin to rapidly adapt, the capacity to regulate the synthesis and degradation of lipids and myelin-specific proteins is essential. During myelin compaction, the cytoplasm is largely excluded from extending oligodendrocyte processes, and is eventually restricted to the paranodal loops that border the nodes of Ranvier and to specialized myelinic channels that connect paranodal cytoplasm to the cell body (Figure 1A). Paranodal loops contain a rich complement of organelles, including peroxisomes (Kassmann et al., 2011), endoplasmic reticulum-like tubules (Nakamura et al., 2020), and mitochondria (Nakamura et al., 2020; Nakamura and Kennedy, 2021). Mitochondria traveling through the cytoplasmic channels of myelin-like compact membrane of oligodendrocytes have been visualized in vitro (Nakamura et al., 2020; Nakamura and Kennedy, 2021), suggesting that similar migration traversing the internode occurs in vivo. To ensure appropriate myelin growth and maintenance, migrating mitochondria will likely be anchored where local lipid turnover is needed. However, no mitochondrial docking protein in oligodendrocytes had been identified. In axons, mitochondria are anchored to microtubules at metabolically demanding sites by the docking protein syntaphilin (SNPH; Lin and Sheng, 2015). Our recent findings demonstrate that SNPH is also expressed by oligodendrocytes and associated with mitochondria (Nakamura et al., 2023). Identifying how mitochondrial dynamics and migration are regulated in myelinating oligodendrocytes is critical to understand the role of mitochondrial metabolism in myelination.
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    K+ channel-mediated retarded maturation of interneurons and its role in neurodevelopmental disorders
    Kaizhen Li, Daria Savitska, Olga Garaschuk
    2024, 19 (7):  1403-1404.  doi: 10.4103/1673-5374.386409
    Abstract ( 94 )   PDF (3338KB) ( 108 )   Save
    De novo mutations in genes encoding K+ channels are implicated in many severe neurodevelopmental disorders. Specifically, mutations in KCNA2, encoding the Shaker-type voltage-gated K+ channel Kv1.2, and KCNJ2, encoding the inwardly rectifying K+ channel Kir2.1, associate with focal and generalized epilepsies, brain atrophy, autism, ataxia and hereditary spastic paraplegia (Syrbe et al., 2015; Masnada et al., 2017; Cheng et al., 2021). Complicated forms of the disease often include other neurological manifestations, such as cognitive impairment/intellectual disability, aggressiveness, irritability, dysarthria, cerebellar atrophy, polyneuropathy, or amyotrophy (Helbig et al., 2016; Masnada et al., 2017). Strikingly, the gain-of-function mutations of Kv1.2 channels, which are supposed to promote neuronal repolarization and termination of neuronal firing, caused more severe symptoms in terms of epilepsy, ataxia, and intellectual disability than the loss-of-function mutations, which are supposed to promote neuronal hyperactivity (Syrbe et al., 2015; Allen et al., 2020). Likewise, gain-of-function mutations in a Kir2.1 channel were shown to be associated with autism spectrum disorder (Cheng et al., 2021). Moreover, a recent study has shown that Kir2.1 is highly expressed in medulloblastoma, one of the most common childhood malignant brain tumors (Wang et al., 2022). In these cells, Kir2.1 promoted tumor cell invasion, metastasis, as well as epithelial-mesenchymal transitions, and higher levels of Kir2.1 expression were associated with the significantly shorter lifespan of the patients. 
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    Abnormal expression of Tau in damaged oligodendrocytes of HLD1 mice
    Tomohiro Torii
    2024, 19 (7):  1405-1406.  doi: 10.4103/1673-5374.387983
    Abstract ( 84 )   PDF (949KB) ( 89 )   Save
    Patients with hypomyelinating leukodystrophies (HLDs), multiple sclerosis (MS), and leukodystrophies including Aicardi-Goutières syndrome, adrenoleukodystrophy, Alexander disease, Canavan disease, cerebrotendinous xanthomatosis, Krabbe disease/globoid cell leukodystrophy, metachromatic leukodystrophy, and Niemann-Pick disease have severe demyelination or hypomyelination. Congenital HLDs are a rare group of disorders characterized by a myelin deficit of the brain that is identified by magnetic resonance imaging, and patients with HLDs typically have nystagmus and motor deficits. In most cases, symptoms begin in infancy and include problems with feeding, a whistling sound when breathing, progressive spasticity leading to joint deformities (contractures) that restrict movement, speech difficulties (dysarthria), ataxia, and seizures. The molecular pathogenesis of HLD1 (also known as Pelizaeus-Merzbacher disease) and MS has been analyzed and well characterized using mouse models such as proteolipid protein 1 (PLP1)-overexpressing transgenic mice (PLP1-tg) (Kagawa et al., 1994) and cuprizone-induced demyelination mice (Bacmeister et al., 2020). The molecular pathology of HLD1 is known to involve an overdose of PLP1 protein, which causes the accumulation of unfolded proteins, leading to the endoplasmic reticulum stress, apoptosis of oligodendrocytes, and demyelination (Figure 1A panel a; Torii et al., 2014). An increasing number of studies have reported genetic mutations that cause similar protein misfolding, dysfunction, and/or mislocalization associated with HLDs. However, these molecular pathology of HLDs are largely unknown because most of HLDs mice have still not been generated yet. On the other hand, cuprizone-induced mice were used as MS mice and were easily generated. Thus, cuprizone-induced demyelination mice have been widely used in research into acute and chronic demyelination disorders and have been well characterized for at least 40 years (Figure 1A panel b).
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    Insight into endoplasmic reticulum-mitochondria contacts in human amyotrophic lateral sclerosis
    Naomi Hartopp, Andrea Markovinovic, Christopher CJ Miller, Patricia Gomez-Suaga
    2024, 19 (7):  1407-1408.  doi: 10.4103/1673-5374.387988
    Abstract ( 90 )   PDF (1484KB) ( 41 )   Save
    Amyotrophic lateral sclerosis (ALS) is a fast-progressing fatal neurodegenerative disease and the most common form of motor neuron disease. There is currently no cure and approximately 90% of cases are sporadic. ALS shares genetic causes, clinical and neuropathological features with frontotemporal dementia, the second most common form of presenile dementia. ALS and frontotemporal dementia are therefore considered a disease spectrum (Abramzon et al., 2020). Various cellular disruptions contribute to disease pathogenesis making effective treatment via a single target challenging. Therapeutic interventions that modulate multiple cellular mechanisms may therefore be most effective in treating such complex diseases.
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    Activity-dependent mechanisms of neuroprotection: promising avenues against dementia
    Davide Tampellini
    2024, 19 (7):  1409-1410.  doi: 10.4103/1673-5374.387985
    Abstract ( 64 )   PDF (685KB) ( 23 )   Save
    The study of the brain and its complex functions is highly fascinating and, at the same time, extremely important. Indeed, furthering our understanding of the biology of neurons and synapses is a prerequisite to uncover the mechanisms involved in memory formation and the coordination of movement as well as their alterations occurring in several neurological disorders. Synapses are specific anatomical structures regulating the correct interaction and function of our neurons and, ultimately, of our brains. Synapses are responsible for the accurate transmission of information from one neuron to another; they are complex though extremely dynamic, and one neuron can form new synapses or eliminate old ones enhancing or reducing the connectivity with another or more neurons, the so-called synaptic plasticity. An important task associated with synapses and their plasticity is the formation and storage of new memories; this event involves specific brain areas including the entorhinal cortex and the hippocampus, which are mainly affected by Alzheimer’s disease (AD).
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    Cell-type resolved transcriptomic approaches for dissecting selective vulnerability in neurodegeneration
    Caleb A. Wood, Nicholas M. Tran
    2024, 19 (7):  1411-1413.  doi: 10.4103/1673-5374.385868
    Abstract ( 119 )   PDF (1297KB) ( 99 )   Save
    A common feature among neurodegenerative conditions is that certain neuronal populations are selectively vulnerable to loss (Fu et al., 2018). By corollary, other neurons are selectively resilient, suggesting they may possess unique features that support their survival. Understanding the basis of neuronal resilience or vulnerability would provide a logical strategy to identify factors that could be targeted therapeutically. Recent advances in cell-type resolved transcriptomic approaches, in particular single-cell RNA-sequencing (scRNA-seq), are enabling the dissection of neuronal resilience/vulnerability with increasing scale and precision across a variety of neurodegenerative conditions. These transcriptomic approaches can yield new insight into degenerative mechanisms but require thoughtful experimental design and analytical methods to be applied to complex disease models. In this perspective, we highlight recent studies focusing on two characteristically distinct forms of neurodegeneration that employ innovative transcriptomic approaches to similarly determine molecular features associating with resilience and vulnerability. First, we discuss studies on retinal ganglion cell (RGC) degeneration after acute axonal injury, a relatively approachable model which has been particularly fruitful for the discovery of genes that mediate neuroprotection and axon regeneration. Next, we present how similar approaches have been extended to study Alzheimer’s disease (AD), where studying selectively vulnerable populations has been historically challenging. Together, the success of these studies in revealing disease modifiers across degenerative conditions serves as a practical demonstration of the general utility of this research framework. In conclusion, cell-type resolved transcriptomics is a powerful approach to studying selective vulnerability and has the potential to spur the development of improved treatments for neurodegenerative conditions where traditional methods have stalled.
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    Medin synergized with vascular amyloid-beta deposits accelerates cognitive decline in Alzheimer’s disease: a potential biomarker
    Xiao Ge, Li Li, Chunming Xie
    2024, 19 (7):  1414.  doi: 10.4103/1673-5374.387995
    Abstract ( 90 )   PDF (303KB) ( 34 )   Save
    Brain vascular dysfunction in Alzheimer’s disease (AD) pathogenesis has become increasingly clear. Accumulating evidence shows that damaged vascular, including large or small vessels and even neurovascular unit, may accelerate the neuropathological process of AD via disrupting brain hypoperfusion, aberrant angiogenesis, and neuroinflammatory response, etc. Thus, vascular dysfunction makes a substantially contribution to the cognitive decline of AD patients. However, how these blood vessels and pathological markers of AD link or interact to influence cognitive function remains unclear. 
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    Regulation of aging by NELF-A and RNA polymerase II elongation
    Chin-Tong Ong, Zhen-Kai Ngian
    2024, 19 (7):  1415-1416.  doi: 10.4103/1673-5374.387989
    Abstract ( 98 )   PDF (482KB) ( 56 )   Save
    Epigenetic regulation of aging: Aging is defined as the gradual decline of physiological function and cellular integrity, causing organismal vulnerability to age-onset diseases and morbidity. Studies in different animal models have led to the identification of twelve aging hallmarks that shared several features: its age-associated manifestation, how experimental manipulation of individual hallmark may alter the trajectory of aging, as well as their interdependence during the process of aging. These hallmarks include genomic instability, telomere attrition, loss of proteostasis, disabled macro-autophagy, deregulated nutrient-sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, chronic inflammation, dysbiosis, altered intercellular communication and epigenetic alterations (Lopez-Otin et al., 2023).
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    Sleep-based neuronal oscillations as a physiological biomarker for Alzheimer’s disease: is night time the right time?
    Jonathan Witton, Erica S. Brady, Michael T. Craig
    2024, 19 (7):  1417-1418.  doi: 10.4103/1673-5374.386412
    Abstract ( 83 )   PDF (1160KB) ( 26 )   Save
    Dementia is a devastating syndrome characterized by memory problems, confusion, and behavior changes that prevent people from performing everyday activities. It is the leading cause of dependency and disability amongst older people, resulting in a global economic cost of ~$1.3 trillion. Around 58 million people are currently afflicted by dementia worldwide, with Alzheimer’s disease (AD) causing most (60–70%) of these cases. Clinical trials for novel disease-modifying therapies for AD have repeatedly been unsuccessful over the past few decades, despite showing great promise in preclinical studies. However, some optimism has been restored in the last year due to the reported success of two novel biologic therapies in phase 3 clinical trials, lecanameb (Dyck et al., 2023) and donanemab (Sims et al., 2023), which were able to significantly slow disease progression in the prodromal phase of AD. Both treatments are monoclonal antibodies that target amyloid-β (Aβ), a protein that aggregates into the extracellular plaques that begin to form in the earliest stages of the disease. These new disease-modifying interventions highlight the key importance that early diagnosis will have if we are to reach the goal of turning AD into a treatable condition.
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    Aberrant adult neurogenesis in intractable epilepsy: can GABAergic progenitor transplantation normalize this process?
    Muhammad N. Arshad, Janice R. Naegele
    2024, 19 (7):  1419-1420.  doi: 10.4103/1673-5374.387994
    Abstract ( 87 )   PDF (1194KB) ( 32 )   Save
    Temporal lobe epilepsy (TLE) is a common type of focal epilepsy characterized by seizure foci within the temporal lobes. While surgical resection of the foci is an established and effective approach for controlling seizures, both temporal lobes cannot be removed, due to their prominent roles in learning and memory. Additionally, seizures induce changes to the temporal lobes that contribute to hyperexcitability, including mossy fiber sprouting, astrogliosis, granule cell (GC) dispersion, and loss of amma-aminobutyric acid (GABA)ergic interneurons (Swartz et al., 2006; Ammothumkandy et al., 2022).
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    A dysregulated calcium homeostasis as the earliest pathological sign in stem cell-derived Parkinson’s disease neurons?
    Nilima Prakash
    2024, 19 (7):  1421-1422.  doi: 10.4103/1673-5374.387986
    Abstract ( 82 )   PDF (1237KB) ( 35 )   Save
    Parkinson’s disease (PD) is characterized by the slow and progressive demise of dopamine (DA)-synthesizing neurons in the substantia nigra pars compacta (SNc), a nucleus located in the human ventral midbrain. Neuron death also affects other regions in the brain at later stages of PD. The concomitant lack of DA in the human forebrain (striatum) leads to the typical motor symptoms of this still uncurable neurodegenerative disorder. However, these symptoms only appear when at least 50% of the SNc DA neurons have already died, resulting in a relatively late diagnosis of PD usually from the sixth decade of life onward (Surmeier et al., 2017). Current PD treatments are only symptomatic and have time-restricted effectiveness, leading to the appearance of serious side effects over time due to maladaptive processes in the brain. They are focused on the reestablishment of the DA supply in the striatum by pharmacological agents or, eventually, the transplantation of DA-producing neurons. In some cases, PD treatment includes the normalization of forebrain motor circuits affected by the lack of DA through electrical (deep brain) stimulation. Early diagnostic markers and disease-modifying therapies for PD are thus urgently needed in the clinic. Ideally, a predisposition to PD ought to be diagnosed for timely interventions, and the irreversible loss of SNc DA and other neurons in the PD brain ought to be prevented altogether or at least slowed to a similar rate to the normal demise of neurons in the aging brain.
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    Working toward an integrated plasticity/network framework for repetitive transcranial magnetic stimulation to inform tailored treatments
    Jessica Moretti, Jennifer Rodger
    2024, 19 (7):  1423-1424.  doi: 10.4103/1673-5374.387990
    Abstract ( 102 )   PDF (799KB) ( 50 )   Save
    Non-invasive brain stimulation techniques (NIBS), including repetitive transcranial magnetic stimulation (rTMS) and transcranial electric stimulation (tES), are increasingly being adopted clinically for treatment of neuropsychiatric and neurological disorders, albeit with varying success. The rationale behind the use of NIBS has historically been that stimulation techniques modulate neuronal activity in the targeted region and consequently induce plasticity which can lead to therapeutic outcomes. However, over the past decade, there has been a marked increase in our understanding of the neurobiological mechanisms of NIBS, in particular for rTMS. The increasing breadth of research in humans and animal models has resulted in a more nuanced understanding of how NIBS affects the brain with the hope for improved therapeutic applications. In this perspective we summarize some of the newly identified mechanisms contributing to NIBS effects, focusing on rTMS, and propose how emerging experimental techniques could be leveraged to further understand and optimize non-invasive brain stimulation. 
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    NLRP3 inflammasome plays a vital role in the pathogenesis of age-related diseases in the eye and brain
    Jack Jonathan Maran, Odunayo Omolola Mugisho
    2024, 19 (7):  1425-1426.  doi: 10.4103/1673-5374.387991
    Abstract ( 88 )   PDF (1687KB) ( 26 )   Save
    Key points: With aging, there is increased nucleotide-binding oligomerization domain-(NOD-) like receptor (NLR) protein-3 (NLRP3) activation in neural and ocular tissues. Activation of the NLRP3 inflammasome appears to be a common denominator in the pathogenesis of age-related diseases of the eye and brain. Pharmacological inhibition of the NLRP3 inflammasome may be a potent therapy for preventing the development and progression of age-related eye and brain diseases.
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    Hydroxytyrosol and Parkinson’s disease: protective actions against alpha-synuclein toxicity
    Ruth Hornedo-Ortega, Ana M. Espinosa-Oliva
    2024, 19 (7):  1427-1428.  doi: 10.4103/1673-5374.387987
    Abstract ( 96 )   PDF (429KB) ( 102 )   Save
    Parkinson’s disease: Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease, after Alzheimer’s disease, affecting 1% of the general population over the age of 65 years. According to data from the World Health Organization (WHO), its prevalence has doubled in the past 25 years. In 2019, global estimates indicated over 8.5 million individuals with PD and it is suggested that PD caused 329000 deaths, an increase of over 100% since 2000 (WHO, 2022). Although there are pharmacological interventions that improve the quality of life of PD patients, this brain disorder still has no cure.
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    Role of pituitary adenylate cyclase-activating polypeptide in peripheral nerve regeneration: a cellular and molecular perspective
    Grazia Maugeri, Velia D’Agata
    2024, 19 (7):  1429-1430.  doi: 10.4103/1673-5374.387992
    Abstract ( 101 )   PDF (406KB) ( 44 )   Save
    Neuroregeneration is a very complex phenomenon characterized by the generation of new neurons and synapses, involving connections between adjacent cells and axonal projections. Neuroregeneration supplies additional long-term resources to replace those altered by the injury and ensure lasting functional recovery. There are substantial differences between the neurodegeneration in the peripheral nervous system (PNS) and the central nervous system (CNS) particularly in terms of extent and speed. In fact, the PNS has remarkable regenerative properties, both morphological and functional, whereas the CNS is most unable to self-repair and regenerate.
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    The neurovascular unit-on-a-chip: modeling ischemic stroke to stem cell therapy
    Seonghun Kim, Minjun Kim, Gerald A. Grant, Wonjae Lee
    2024, 19 (7):  1431-1432.  doi: 10.4103/1673-5374.385296
    Abstract ( 92 )   PDF (9278KB) ( 38 )   Save
    The neurovascular unit and stem cell therapy in ischemic stroke: Ischemic stroke, accounts for approximately 85% of all stroke incidents and is a major global health burden. It is the leading cause of disability and death worldwide, posing immense societal and economic challenges due to the long-term care required for stroke survivors and the significant healthcare costs associated with its treatment and management (Amarenco et al., 2009). Ischemic stroke inflicts damage that spans multiple aspects, disrupts cerebral blood flow, and leads to a cascade of deleterious events including cellular excitotoxicity, oxidative stress, neuroinflammation, and subsequent neuronal degeneration (Macrez et al., 2011). The neurovascular unit (NVU), a minimal functional unit within the brain, encompasses neurons, astrocytes, microglia, oligodendrocytes, pericytes, and endothelial cells. This complex ensemble is pivotal in maintaining the blood-brain barrier (BBB) integrity and stabilizing the cerebral microenvironment. In the context of ischemic stroke, the NVU not only embodies the disease’s pathological spectrum but also significantly contributes to post-stroke restoration. Damage to the NVU during ischemic stroke disrupts its structural and functional integrity, increases BBB permeability, and induces neuroinflammatory responses. The intricate interactions among the NVU’s cellular and extracellular components are instrumental in tissue repair, angiogenesis, neurogenesis, and functional recovery following a stroke (Wang et al., 2021).
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    Combining neural progenitor cell transplant and rehabilitation for enhanced recovery after cervical spinal cord injury
    Camila M. Freria, Paul Lu
    2024, 19 (7):  1433-1434.  doi: 10.4103/1673-5374.387993
    Abstract ( 82 )   PDF (1032KB) ( 63 )   Save
    Efforts to promote recovery of function after human spinal cord injury (SCI) will likely require interventions targeting the corticospinal tract (CST) motor system: the most important pathway for voluntary motor control in humans. This system has historically been the most refractory to regenerative efforts after SCI. The “non-regeneration” of the CST changed when robust regeneration of the CST into spared tissue was demonstrated by the inactivation of phosphatase and tensin homolog and delivery of inosine. However, a permissive growth matrix was required to achieve CST regeneration into a lesion site (Lu et al., 2012; Kadoya et al., 2016). This was provided by neural progenitor cell (NPC) grafts driven to spinal cord fates (Kadoya et al., 2016). Grafted NPCs differentiate to form new circuitry with the host spinal cord including neurons below the lesion site. However, these new circuits may not form appropriate connections with host neurons in the injured adult spinal cord due to a lack of spatial and temporal regulated axonal guidance cues present during development (Kaplan et al., 2014). Thus, the formation of these new connective circuits must be trained to form functional relays to reconnect the spinal cord and brain through appropriate targets.
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    Modeling mitochondria, where are the numbers?
    Adrian M. Davies, Alan G. Holt
    2024, 19 (7):  1435-1436.  doi: 10.4103/1673-5374.386402
    Abstract ( 90 )   PDF (415KB) ( 21 )   Save
    Models and simulations are particularly useful for exploring ideas and concepts in the biological sciences that are experimentally impracticable.
    In silico methods are also gaining acceptance with regulatory authorities as an alternative to animal testing. For example, the Environmental Protection Agency aims to eliminate animal testing by 2035, and both the Food and Drug Administration and European Medicine Agency no longer require animal testing for biosimilars or generic products if the in vitro and in silico data is acceptable.
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    Rethinking neurodegenerative diseases: neurometabolic concept linking lipid oxidation to diseases in the central nervous system
    Steinunn Sara Helgudóttir, Anne Skøttrup Mørkholt, Jacek Lichota, Preben Bruun-Nyzell, Mads Christian Andersen, Nanna Marie Juhl Kristensen, Amanda Krøger Johansen, Mikela Reinholdt Zinn, Hulda Maria Jensdóttir, John Dirk Vestergaard Nieland
    2024, 19 (7):  1437-1445.  doi: 10.4103/1673-5374.387965
    Abstract ( 169 )   PDF (955KB) ( 122 )   Save
    Currently, there is a lack of effective medicines capable of halting or reversing the progression of neurodegenerative disorders, including amyotrophic lateral sclerosis, Parkinson’s disease, multiple sclerosis, or Alzheimer’s disease. Given the unmet medical need, it is necessary to reevaluate the existing paradigms of how to target these diseases. When considering neurodegenerative diseases from a systemic neurometabolic perspective, it becomes possible to explain the shared pathological features. This innovative approach presented in this paper draws upon extensive research conducted by the authors and researchers worldwide. In this review, we highlight the importance of metabolic mitochondrial dysfunction in the context of neurodegenerative diseases. We provide an overview of the risk factors associated with developing neurodegenerative disorders, including genetic, epigenetic, and environmental factors. Additionally, we examine pathological mechanisms implicated in these diseases such as oxidative stress, accumulation of misfolded proteins, inflammation, demyelination, death of neurons, insulin resistance, dysbiosis, and neurotransmitter disturbances. Finally, we outline a proposal for the restoration of mitochondrial metabolism, a crucial aspect that may hold the key to facilitating curative therapeutic interventions for neurodegenerative disorders in forthcoming advancements.
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    Neuronal conversion from glia to replenish the lost neurons
    Shiyu Liang, Jing Zhou, Xiaolin Yu, Shuai Lu, Ruitian Liu
    2024, 19 (7):  1446-1453.  doi: 10.4103/1673-5374.386400
    Abstract ( 202 )   PDF (2497KB) ( 165 )   Save
    Neuronal injury, aging, and cerebrovascular and neurodegenerative diseases such as cerebral infarction, Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia, amyotrophic lateral sclerosis, and Huntington’s disease are characterized by significant neuronal loss. Unfortunately, the neurons of most mammals including humans do not possess the ability to self-regenerate. Replenishment of lost neurons becomes an appealing therapeutic strategy to reverse the disease phenotype. Transplantation of pluripotent neural stem cells can supplement the missing neurons in the brain, but it carries the risk of causing gene mutation, tumorigenesis, severe inflammation, and obstructive hydrocephalus induced by brain edema. Conversion of neural or non-neural lineage cells into functional neurons is a promising strategy for the diseases involving neuron loss, which may overcome the above-mentioned disadvantages of neural stem cell therapy. Thus far, many strategies to transform astrocytes, fibroblasts, microglia, Müller glia, NG2 cells, and other glial cells to mature and functional neurons, or for the conversion between neuronal subtypes have been developed through the regulation of transcription factors, polypyrimidine tract binding protein 1 (PTBP1), and small chemical molecules or are based on a combination of several factors and the location in the central nervous system. However, some recent papers did not obtain expected results, and discrepancies exist. Therefore, in this review, we discuss the history of neuronal transdifferentiation, summarize the strategies for neuronal replenishment and conversion from glia, especially astrocytes, and point out that biosafety, new strategies, and the accurate origin of the truly converted neurons in vivo should be focused upon in future studies. It also arises the attention of replenishing the lost neurons from glia by gene therapies such as up-regulation of some transcription factors or down-regulation of PTBP1 or drug interference therapies. 
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    Cognitive impairment in cerebral small vessel disease induced by hypertension
    Weipeng Wei, Denglei Ma, Lin Li, Lan Zhang
    2024, 19 (7):  1454-1462.  doi: 10.4103/1673-5374.385841
    Abstract ( 129 )   PDF (681KB) ( 107 )   Save
    Hypertension is a primary risk factor for the progression of cognitive impairment caused by cerebral small vessel disease, the most common cerebrovascular disease. However, the causal relationship between hypertension and cerebral small vessel disease remains unclear. Hypertension has substantial negative impacts on brain health and is recognized as a risk factor for cerebrovascular disease. Chronic hypertension and lifestyle factors are associated with risks for stroke and dementia, and cerebral small vessel disease can cause dementia and stroke. Hypertension is the main driver of cerebral small vessel disease, which changes the structure and function of cerebral vessels via various mechanisms and leads to lacunar infarction, leukoaraiosis, white matter lesions, and intracerebral hemorrhage, ultimately resulting in cognitive decline and demonstrating that the brain is the target organ of hypertension. This review updates our understanding of the pathogenesis of hypertension-induced cerebral small vessel disease and the resulting changes in brain structure and function and declines in cognitive ability. We also discuss drugs to treat cerebral small vessel disease and cognitive impairment.
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    α-Synuclein pathology from the body to the brain: so many seeds so close to the central soil#br#
    Yunying Yang, Zhentao Zhang
    2024, 19 (7):  1463-1472.  doi: 10.4103/1673-5374.387967
    Abstract ( 329 )   PDF (1117KB) ( 336 )   Save
    α-Synuclein is a protein that mainly exists in the presynaptic terminals. Abnormal folding and accumulation of α-synuclein are found in several neurodegenerative diseases, including Parkinson’s disease. Aggregated and highly phosphorylated α-synuclein constitutes the main component of Lewy bodies in the brain, the pathological hallmark of Parkinson’s disease. For decades, much attention has been focused on the accumulation of α-synuclein in the brain parenchyma rather than considering Parkinson’s disease as a systemic disease. Recent evidence demonstrates that, at least in some patients, the initial α-synuclein pathology originates in the peripheral organs and spreads to the brain. Injection of α-synuclein preformed fibrils into the gastrointestinal tract triggers the gut-to-brain propagation of α-synuclein pathology. However, whether α-synuclein pathology can occur spontaneously in peripheral organs independent of exogenous α-synuclein preformed fibrils or pathological α-synuclein leakage from the central nervous system remains under investigation. In this review, we aimed to summarize the role of peripheral α-synuclein pathology in the pathogenesis of Parkinson’s disease. We also discuss the pathways by which α-synuclein pathology spreads from the body to the brain.
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    Lactate: a prospective target for therapeutic intervention in psychiatric disease
    Yanhui Cai, Haiyun Guo, Tianle Han, Huaning Wang
    2024, 19 (7):  1473-1479.  doi: 10.4103/1673-5374.387969
    Abstract ( 404 )   PDF (2673KB) ( 110 )   Save
    Although antipsychotics that act via monoaminergic neurotransmitter modulation have considerable therapeutic effect, they cannot completely relieve clinical symptoms in patients suffering from psychiatric disorders. This may be attributed to the limited range of neurotransmitters that are regulated by psychotropic drugs. Recent findings indicate the need for investigation of psychotropic medications that target less-studied neurotransmitters. Among these candidate neurotransmitters, lactate is developing from being a waste metabolite to a glial-neuronal signaling molecule in recent years. Previous studies have suggested that cerebral lactate levels change considerably in numerous psychiatric illnesses; animal experiments have also shown that the supply of exogenous lactate exerts an antidepressant effect. In this review, we have described how medications targeting newer neurotransmitters offer promise in psychiatric diseases; we have also summarized the advances in the use of lactate (and its corresponding signaling pathways) as a signaling molecule. In addition, we have described the alterations in brain lactate levels in depression, anxiety, bipolar disorder, and schizophrenia and have indicated the challenges that need to be overcome before brain lactate can be used as a therapeutic target in psychopharmacology.
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    Gut flora in multiple sclerosis: implications for pathogenesis and treatment
    Weiwei Zhang, Ying Wang, Mingqin Zhu, Kangding Liu, Hong-Liang Zhang
    2024, 19 (7):  1480-1488.  doi: 10.4103/1673-5374.387974
    Abstract ( 207 )   PDF (5033KB) ( 191 )   Save
    Multiple sclerosis is an inflammatory disorder characterized by inflammation, demyelination, and neurodegeneration in the central nervous system. Although current first-line therapies can help manage symptoms and slow down disease progression, there is no cure for multiple sclerosis. The gut-brain axis refers to complex communications between the gut flora and the immune, nervous, and endocrine systems, which bridges the functions of the gut and the brain. Disruptions in the gut flora, termed dysbiosis, can lead to systemic inflammation, leaky gut syndrome, and increased susceptibility to infections. The pathogenesis of multiple sclerosis involves a combination of genetic and environmental factors, and gut flora may play a pivotal role in regulating immune responses related to multiple sclerosis. To develop more effective therapies for multiple sclerosis, we should further uncover the disease processes involved in multiple sclerosis and gain a better understanding of the gut-brain axis. This review provides an overview of the role of the gut flora in multiple sclerosis
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    Targeting tau in Alzheimer’s disease: from mechanisms to clinical therapy
    Jinwang Ye, Huali Wan, Sihua Chen, Gong-Ping Liu
    2024, 19 (7):  1489-1498.  doi: 10.4103/1673-5374.385847
    Abstract ( 390 )   PDF (933KB) ( 161 )   Save
    Alzheimer’s disease is the most prevalent neurodegenerative disease affecting older adults. Primary features of Alzheimer’s disease include extracellular aggregation of amyloid-β plaques and the accumulation of neurofibrillary tangles, formed by tau protein, in the cells. While there are amyloid-β-targeting therapies for the treatment of Alzheimer’s disease, these therapies are costly and exhibit potential negative side effects. Mounting evidence suggests significant involvement of tau protein in Alzheimer’s disease-related neurodegeneration. As an important microtubule-associated protein, tau plays an important role in maintaining the stability of neuronal microtubules and promoting axonal growth. In fact, clinical studies have shown that abnormal phosphorylation of tau protein occurs before accumulation of amyloid-β in the brain. Various therapeutic strategies targeting tau protein have begun to emerge, and are considered possible methods to prevent and treat Alzheimer’s disease. Specifically, abnormalities in post-translational modifications of the tau protein, including aberrant phosphorylation, ubiquitination, small ubiquitin-like modifier (SUMO)ylation, acetylation, and truncation, contribute to its microtubule dissociation, misfolding, and subcellular missorting. This causes mitochondrial damage, synaptic impairments, gliosis, and neuroinflammation, eventually leading to neurodegeneration and cognitive deficits. This review summarizes the recent findings on the underlying mechanisms of tau protein in the onset and progression of Alzheimer’s disease and discusses tau-targeted treatment of Alzheimer’s disease.
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    Genetic pathways in cerebral palsy: a review of the implications for precision diagnosis and understanding disease mechanisms
    Yiran Xu, Yifei Li, Seidu A. Richard, Yanyan Sun, Changlian Zhu
    2024, 19 (7):  1499-1508.  doi: 10.4103/1673-5374.385855
    Abstract ( 122 )   PDF (1640KB) ( 229 )   Save
    Cerebral palsy is a diagnostic term utilized to describe a group of permanent disorders affecting movement and posture. Patients with cerebral palsy are often only capable of limited activity, resulting from non-progressive disturbances in the fetal or neonatal brain. These disturbances severely impact the child’s daily life and impose a substantial economic burden on the family. Although cerebral palsy encompasses various brain injuries leading to similar clinical outcomes, the understanding of its etiological pathways remains incomplete owing to its complexity and heterogeneity. This review aims to summarize the current knowledge on the genetic factors influencing cerebral palsy development. It is now widely acknowledged that genetic mutations and alterations play a pivotal role in cerebral palsy development, which can be further influenced by environmental factors. Despite continuous research endeavors, the underlying factors contributing to cerebral palsy remain are still elusive. However, significant progress has been made in genetic research that has markedly enhanced our comprehension of the genetic factors underlying cerebral palsy development. Moreover, these genetic factors have been categorized based on the identified gene mutations in patients through clinical genotyping, including thrombosis, angiogenesis, mitochondrial and oxidative phosphorylation function, neuronal migration, and cellular autophagy. Furthermore, exploring targeted genotypes holds potential for precision treatment. In conclusion, advancements in genetic research have substantially improved our understanding of the genetic causes underlying cerebral palsy. These breakthroughs have the potential to pave the way for new treatments and therapies, consequently shaping the future of cerebral palsy research and its clinical management. The investigation of cerebral palsy genetics holds the potential to significantly advance treatments and management strategies. By elucidating the underlying cellular mechanisms, we can develop targeted interventions to optimize outcomes. A continued collaboration between researchers and clinicians is imperative to comprehensively unravel the intricate genetic etiology of cerebral palsy.
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    Gabapentinoids for the treatment of stroke
    Ying Zhang, Chenyu Zhang, Xiaoli Yi, Qi Wang, Tiejun Zhang, Yuwen Li
    2024, 19 (7):  1509-1516.  doi: 10.4103/1673-5374.387968
    Abstract ( 262 )   PDF (16185KB) ( 78 )   Save
    Gabapentinoid drugs (pregabalin and gabapentin) have been successfully used in the treatment of neuropathic pain and in focal seizure prevention. Recent research has demonstrated their potent activities in modulating neurotransmitter release in neuronal tissue, oxidative stress, and inflammation, which matches the mechanism of action via voltage-gated calcium channels. In this review, we briefly elaborate on the medicinal history and ligand-binding sites of gabapentinoids. We systematically summarize the preclinical and clinical research on gabapentinoids in stroke, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, seizures after stroke, cortical spreading depolarization after stroke, pain after stroke, and nerve regeneration after stroke. This review also discusses the potential targets of gabapentinoids in stroke; however, the existing results are still uncertain regarding the effect of gabapentinoids on stroke and related diseases. Further preclinical and clinical trials are needed to test the therapeutic potential of gabapentinoids in stroke. Therefore, gabapentinoids have both opportunities and challenges in the treatment of stroke. 
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    Functional near-infrared spectroscopy in non-invasive neuromodulation
    Congcong Huo, Gongcheng Xu, Hui Xie, Tiandi Chen, Guangjian Shao, Jue Wang, Wenhao Li, Daifa Wang, Zengyong Li
    2024, 19 (7):  1517-1522.  doi: 10.4103/1673-5374.387970
    Abstract ( 542 )   PDF (3163KB) ( 240 )   Save
    Non-invasive cerebral neuromodulation technologies are essential for the reorganization of cerebral neural networks, which have been widely applied in the field of central neurological diseases, such as stroke, Parkinson’s disease, and mental disorders. Although significant advances have been made in neuromodulation technologies, the identification of optimal neurostimulation parameters including the cortical target, duration, and inhibition or excitation pattern is still limited due to the lack of guidance for neural circuits. Moreover, the neural mechanism underlying neuromodulation for improved behavioral performance remains poorly understood. Recently, advancements in neuroimaging have provided insight into neuromodulation techniques. Functional near-infrared spectroscopy, as a novel non-invasive optical brain imaging method, can detect brain activity by measuring cerebral hemodynamics with the advantages of portability, high motion tolerance, and anti-electromagnetic interference. Coupling functional near-infrared spectroscopy with neuromodulation technologies offers an opportunity to monitor the cortical response, provide real-time feedback, and establish a closed-loop strategy integrating evaluation, feedback, and intervention for neurostimulation, which provides a theoretical basis for development of individualized precise neurorehabilitation. We aimed to summarize the advantages of functional near-infrared spectroscopy and provide an overview of the current research on functional near-infrared spectroscopy in transcranial magnetic stimulation, transcranial electrical stimulation, neurofeedback, and brain-computer interfaces. Furthermore, the future perspectives and directions for the application of functional near-infrared spectroscopy in neuromodulation are summarized. In conclusion, functional near-infrared spectroscopy combined with neuromodulation may promote the optimization of central neural reorganization to achieve better functional recovery from central nervous system diseases.
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    MicroRNAs as potential biomarkers for diagnosis of schizophrenia and influence of antipsychotic treatment
    Bridget Martinez, Philip V. Peplow
    2024, 19 (7):  1523-1531.  doi: 10.4103/1673-5374.387966
    Abstract ( 94 )   PDF (671KB) ( 66 )   Save
    Characterized by positive symptoms (such as changes in behavior or thoughts, including delusions and hallucinations), negative symptoms (such as apathy, anhedonia, and social withdrawal), and cognitive impairments, schizophrenia is a chronic, severe, and disabling mental disorder with late adolescence or early adulthood onset. Antipsychotics are the most commonly used drugs to treat schizophrenia, but those currently in use do not fully reverse all three types of symptoms characterizing this condition. Schizophrenia is frequently misdiagnosed, resulting in a delay of or inappropriate treatment. Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of schizophrenia. The recent studies reviewed included microRNA profiling in blood- and urine-based materials and nervous tissue materials. From the studies that had validated the preliminary findings, potential candidate biomarkers for schizophrenia in adults could be miR-22-3p, -30e-5p, -92a-3p, -148b-5p, -181a-3p, -181a-5p, -181b-5p, -199b-5p, -137 in whole blood, and miR-130b, -193a-3p in blood plasma. Antipsychotic treatment of schizophrenia patients was found to modulate the expression of certain microRNAs including miR-130b, -193a-3p, -132, -195, -30e, -432 in blood plasma. Further studies are warranted with adolescents and young adults having schizophrenia and consideration should be given to using animal models of the disorder to investigate the effect of suppressing or overexpressing specific microRNAs.
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    Hemorrhagic transformation in patients with large-artery atherosclerotic stroke is associated with the gut microbiota and lipopolysaccharide
    Qin Huang, Minping Wei, Xianjing Feng, Yunfang Luo, Yunhai Liu, Jian Xia
    2024, 19 (7):  1532-1540.  doi: 10.4103/1673-5374.385846
    Abstract ( 115 )   PDF (8399KB) ( 58 )   Save
    Hemorrhagic transformation is a major complication of large-artery atherosclerotic stroke (a major ischemic stroke subtype) that worsens outcomes and increases mortality. Disruption of the gut microbiota is an important feature of stroke, and some specific bacteria and bacterial metabolites may contribute to hemorrhagic transformation pathogenesis. We aimed to investigate the relationship between the gut microbiota and hemorrhagic transformation in large-artery atherosclerotic stroke. An observational retrospective study was conducted. From May 2020 to September 2021, blood and fecal samples were obtained upon admission from 32 patients with first-ever acute ischemic stroke and not undergoing intravenous thrombolysis or endovascular thrombectomy, as well as 16 healthy controls. Patients with stroke who developed hemorrhagic transformation (n = 15) were compared to those who did not develop hemorrhagic transformation (n = 17) and with healthy controls. The gut microbiota was assessed through 16S ribosomal ribonucleic acid sequencing. We also examined key components of the lipopolysaccharide pathway: lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14. We observed that bacterial diversity was decreased in both the hemorrhagic transformation and non-hemorrhagic transformation group compared with the healthy controls. The patients with ischemic stroke who developed hemorrhagic transformation exhibited altered gut microbiota composition, in particular an increase in the relative abundance and diversity of members belonging to the Enterobacteriaceae family. Plasma lipopolysaccharide and lipopolysaccharide-binding protein levels were higher in the hemorrhagic transformation group compared with the non-hemorrhagic transformation group. lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14 concentrations were associated with increased abundance of Enterobacteriaceae. Next, the role of the gut microbiota in hemorrhagic transformation was evaluated using an experimental stroke rat model. In this model, transplantation of the gut microbiota from hemorrhagic transformation rats into the recipient rats triggered higher plasma levels of lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14. Taken together, our findings demonstrate a noticeable change in the gut microbiota and lipopolysaccharide-related inflammatory response in stroke patients with hemorrhagic transformation. This suggests that maintaining a balanced gut microbiota may be an important factor in preventing hemorrhagic transformation after stroke.
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    Activation of the Wnt/β-catenin/CYP1B1 pathway alleviates oxidative stress and protects the blood-brain barrier under cerebral ischemia/reperfusion conditions
    Xingyong Chen, Nannan Yao, Yanguang Mao, Dongyun Xiao, Yiyi Huang, Xu Zhang, Yinzhou Wang
    2024, 19 (7):  1541-1547.  doi: 10.4103/1673-5374.386398
    Abstract ( 230 )   PDF (10000KB) ( 106 )   Save
    Accumulating evidence suggests that oxidative stress and the Wnt/β-catenin pathway participate in stroke-induced disruption of the blood-brain barrier. However, the potential links between them following ischemic stroke remain largely unknown. The present study found that cerebral ischemia leads to oxidative stress and repression of the Wnt/β-catenin pathway. Meanwhile, Wnt/β-catenin pathway activation by the pharmacological inhibitor, TWS119, relieved oxidative stress, increased the levels of cytochrome P450 1B1 (CYP1B1) and tight junction-associated proteins (zonula occludens-1 [ZO-1], occludin and claudin-5), as well as brain microvascular density in cerebral ischemia rats. Moreover, rat brain microvascular endothelial cells that underwent oxygen glucose deprivation/reoxygenation displayed intense oxidative stress, suppression of the Wnt/β-catenin pathway, aggravated cell apoptosis, downregulated CYP1B1 and tight junction protein levels, and inhibited cell proliferation and migration. Overexpression of β-catenin or knockdown of β-catenin and CYP1B1 genes in rat brain microvascular endothelial cells at least partly ameliorated or exacerbated these effects, respectively. In addition, small interfering RNA-mediated β-catenin silencing decreased CYP1B1 expression, whereas CYP1B1 knockdown did not change the levels of glycogen synthase kinase 3β, Wnt-3a, and β-catenin proteins in rat brain microvascular endothelial cells after oxygen glucose deprivation/reoxygenation. Thus, the data suggest that CYP1B1 can be regulated by Wnt/β-catenin signaling, and activation of the Wnt/β-catenin/CYP1B1 pathway contributes to alleviation of oxidative stress, increased tight junction levels, and protection of the blood-brain barrier against ischemia/hypoxia-induced injury.
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    Reduction of epinephrine in the lumbar spinal cord following repetitive blast-induced traumatic brain injury in rats
    Shigeharu Tsuda, Mustafa Golam, Jiamei Hou, Kevin K.W. Wang, Floyd J. Thompson, Prodip Bose
    2024, 19 (7):  1548-1552.  doi: 10.4103/1673-5374.385838
    Abstract ( 94 )   PDF (959KB) ( 53 )   Save
    Traumatic brain injury-induced unfavorable outcomes in human patients have independently been associated with dysregulated levels of monoamines, especially epinephrine, although few preclinical studies have examined the epinephrine level in the central nervous system after traumatic brain injury. Epinephrine has been shown to regulate the activities of spinal motoneurons as well as increase the heart rate, blood pressure, and blood flow to the hindlimb muscles. Therefore, the purpose of the present study was to determine the impact of repeated blast-induced traumatic brain injury on the epinephrine levels in several function-specific central nervous system regions in rats. Following three repeated blast injuries at 3-day intervals, the hippocampus, motor cortex, locus coeruleus, vestibular nuclei, and lumbar spinal cord were harvested at post-injury day eight and processed for epinephrine assays using a high-sensitive electrochemical detector coupled with high-performance liquid chromatography. Our results showed that the epinephrine levels were significantly decreased in the lumbar spinal cord tissues of blast-induced traumatic brain injury animals compared to the levels detected in age- and sex-matched sham controls. In other function-specific central nervous system regions, although the epinephrine levels were slightly altered following blast-induced traumatic brain injury, they were not statistically significant. These results suggest that blast injury-induced significant downregulation of epinephrine in the lumbar spinal cord could negatively impact the motor and cardiovascular function. This is the first report to show altered epinephrine levels in the spinal cord following repetitive mild blast-induced traumatic brain injury.
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    Structural and functional connectivity of the whole brain and subnetworks in individuals with mild traumatic brain injury: predictors of patient prognosis
    Sihong Huang, Jungong Han, Hairong Zheng, Mengjun Li, Chuxin Huang, Xiaoyan Kui, Jun Liu
    2024, 19 (7):  1553-1558.  doi: 10.4103/1673-5374.387971
    Abstract ( 148 )   PDF (10158KB) ( 66 )   Save
    Patients with mild traumatic brain injury have a diverse clinical presentation, and the underlying pathophysiology remains poorly understood. Magnetic resonance imaging is a non-invasive technique that has been widely utilized to investigate neurobiological markers after mild traumatic brain injury. This approach has emerged as a promising tool for investigating the pathogenesis of mild traumatic brain injury. Graph theory is a quantitative method of analyzing complex networks that has been widely used to study changes in brain structure and function. However, most previous mild traumatic brain injury studies using graph theory have focused on specific populations, with limited exploration of simultaneous abnormalities in structural and functional connectivity. Given that mild traumatic brain injury is the most common type of traumatic brain injury encountered in clinical practice, further investigation of the patient characteristics and evolution of structural and functional connectivity is critical. In the present study, we explored whether abnormal structural and functional connectivity in the acute phase could serve as indicators of longitudinal changes in imaging data and cognitive function in patients with mild traumatic brain injury. In this longitudinal study, we enrolled 46 patients with mild traumatic brain injury who were assessed within 2 weeks of injury, as well as 36 healthy controls. Resting-state functional magnetic resonance imaging and diffusion-weighted imaging data were acquired for graph theoretical network analysis. In the acute phase, patients with mild traumatic brain injury demonstrated reduced structural connectivity in the dorsal attention network. More than 3 months of follow-up data revealed signs of recovery in structural and functional connectivity, as well as cognitive function, in 22 out of the 46 patients. Furthermore, better cognitive function was associated with more efficient networks. Finally, our data indicated that small-worldness in the acute stage could serve as a predictor of longitudinal changes in connectivity in patients with mild traumatic brain injury. These findings highlight the importance of integrating structural and functional connectivity in understanding the occurrence and evolution of mild traumatic brain injury. Additionally, exploratory analysis based on subnetworks could serve a predictive function in the prognosis of patients with mild traumatic brain injury.
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    A “messenger zone hypothesis” based on the visual three-dimensional spatial distribution of motoneurons innervating deep limb muscles
    Chen Huang, Shen Wang, Jin Deng, Xinyi Gu, Shuhang Guo, Xiaofeng Yin
    2024, 19 (7):  1559-1567.  doi: 10.4103/1673-5374.387972
    Abstract ( 193 )   PDF (10526KB) ( 100 )   Save
    Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneurons. However, current research on the spatial location of the spinal motoneurons innervating different muscles is limited. In this study, we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs, which were innervated by the obturator nerve, femoral nerve, inferior gluteal nerve, deep peroneal nerve, and tibial nerve. Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared organs (3DISCO) and 3-D imaging technology based on lightsheet fluorescence microscopy (LSFM). Additionally, we propose the hypothesis that “messenger zones” exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups. We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons. Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse. Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles, but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.
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    Fibroblast growth factor 21 inhibits ferroptosis following spinal cord injury by regulating heme oxygenase-1
    Qi Gu, Weiping Sha, Qun Huang, Jin Wang, Yi Zhu, Tianli Xu, Zhenhua Xu, Qiancheng Zhu, Jianfei Ge, Shoujin Tian, Xiaolong Lin
    2024, 19 (7):  1568-1574.  doi: 10.4103/1673-5374.387979
    Abstract ( 131 )   PDF (17353KB) ( 64 )   Save
    Interfering with the ferroptosis pathway is a new strategy for the treatment of spinal cord injury. Fibroblast growth factor 21 can inhibit ferroptosis and promote neurofunctional recovery, while heme oxygenase-1 is a regulator of iron and reactive oxygen species homeostasis. The relationship between heme oxygenase-1 and ferroptosis remains controversial. In this study, we used a spinal cord injury rat model to show that the levels of fibroblast growth factor 21 in spinal cord tissue decreased after spinal cord injury. In addition, there was a significant aggravation of ferroptosis and a rapid increase in heme oxygenase-1 expression after spinal cord injury. Further, heme oxygenase-1 aggravated ferroptosis after spinal cord injury, while fibroblast growth factor 21 inhibited ferroptosis by downregulating heme oxygenase-1. Thus, the activation of fibroblast growth factor 21 may provide a potential treatment for spinal cord injury. These findings could provide a new potential mechanistic explanation for fibroblast growth factor 21 in the treatment of spinal cord injury.
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    Runx2 regulates peripheral nerve regeneration to promote Schwann cell migration and re-myelination
    Rong Hu, Xinpeng Dun, Lolita Singh, Matthew C. Banton
    2024, 19 (7):  1575-1583.  doi: 10.4103/1673-5374.387977
    Abstract ( 233 )   PDF (24107KB) ( 88 )   Save
    Runx2 is a major regulator of osteoblast differentiation and function; however, the role of Runx2 in peripheral nerve repair is unclear. Here, we analyzed Runx2 expression following injury and found that it was specifically up-regulated in Schwann cells. Furthermore, using Schwann cell-specific Runx2 knockout mice, we studied peripheral nerve development and regeneration and found that multiple steps in the regeneration process following sciatic nerve injury were Runx2-dependent. Changes observed in Runx2 knockout mice include increased proliferation of Schwann cells, impaired Schwann cell migration and axonal regrowth, reduced re-myelination of axons, and a block in macrophage clearance in the late stage of regeneration. Taken together, our findings indicate that Runx2 is a key regulator of Schwann cell plasticity, and therefore peripheral nerve repair. Thus, our study shows that Runx2 plays a major role in Schwann cell migration, re-myelination, and peripheral nerve functional recovery following injury.
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    Effects of mesenchymal stem cell on dopaminergic neurons, motor and memory functions in animal models of Parkinson’s disease: a systematic review and meta-analysis
    Jong Mi Park, Masoud Rahmati, Sang Chul Lee, Jae Il Shin, Yong Wook Kim
    2024, 19 (7):  1584-1592.  doi: 10.4103/1673-5374.387976
    Abstract ( 141 )   PDF (14949KB) ( 66 )   Save
    Parkinson’s disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, and although restoring striatal dopamine levels may improve symptoms, no treatment can cure or reverse the disease itself. Stem cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of Parkinson’s disease. Mesenchymal stem cells are considered a promising option due to fewer ethical concerns, a lower risk of immune rejection, and a lower risk of teratogenicity. We performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function, memory, and preservation of dopaminergic neurons in a Parkinson’s disease animal model. We searched bibliographic databases (PubMed/MEDLINE, Embase, CENTRAL, Scopus, and Web of Science) to identify articles and included only peer-reviewed in vivo interventional animal studies published in any language through June 28, 2023. The study utilized the random-effect model to estimate the 95% confidence intervals (CI) of the standard mean differences (SMD) between the treatment and control groups. We use the systematic review center for laboratory animal experimentation’s risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment. A total of 33 studies with data from 840 Parkinson’s disease model animals were included in the meta-analysis. Treatment with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational test. Among the stem cell types, the bone marrow MSCs with neurotrophic factor group showed largest effect size (SMD [95% CI] = –6.21 [–9.50 to –2.93], P = 0.0001, I2 = 0.0 %). The stem cell treatment group had significantly more tyrosine hydroxylase positive dopaminergic neurons in the striatum ([95% CI] = 1.04 [0.59 to 1.49], P = 0.0001, I2 = 65.1 %) and substantia nigra (SMD [95% CI] = 1.38 [0.89 to 1.87], P = 0.0001, I2 = 75.3 %), indicating a protective effect on dopaminergic neurons. Subgroup analysis of the amphetamine-induced rotation test showed a significant reduction only in the intracranial-striatum route (SMD [95% CI] = –2.59 [–3.25 to –1.94], P = 0.0001, I2 = 74.4 %). The memory test showed significant improvement only in the intravenous route (SMD [95% CI] = 4.80 [1.84 to 7.76], P = 0.027, I2 = 79.6 %). Mesenchymal stem cells have been shown to positively impact motor function and memory function and protect dopaminergic neurons in preclinical models of Parkinson’s disease. Further research is required to determine the optimal stem cell types, modifications, transplanted cell numbers, and delivery methods for these protocols.
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    Neural stem cell-derived exosomes promote mitochondrial biogenesis and restore abnormal protein distribution in a mouse model of Alzheimer’s disease
    Bo Li, Yujie Chen, Yan Zhou, Xuanran Feng, Guojun Gu, Shuang Han, Nianhao Cheng, Yawen Sun, Yiming Zhang, Jiahui Cheng, Qi Zhang, Wei Zhang, Jianhui Liu
    2024, 19 (7):  1593-1601.  doi: 10.4103/1673-5374.385839
    Abstract ( 164 )   PDF (13771KB) ( 121 )   Save
    Mitochondrial dysfunction is a hallmark of Alzheimer’s disease. We previously showed that neural stem cell-derived extracellular vesicles improved mitochondrial function in the cortex of APP/PS1 mice. Because Alzheimer’s disease affects the entire brain, further research is needed to elucidate alterations in mitochondrial metabolism in the brain as a whole. Here, we investigated the expression of several important mitochondrial biogenesis-related cytokines in multiple brain regions after treatment with neural stem cell-derived exosomes and used a combination of whole brain clearing, immunostaining, and lightsheet imaging to clarify their spatial distribution. Additionally, to clarify whether the sirtuin 1 (SIRT1)-related pathway plays a regulatory role in neural stem cell-derived exosomes interfering with mitochondrial functional changes, we generated a novel nervous system-SIRT1 conditional knockout APP/PS1 mouse model. Our findings demonstrate that neural stem cell-derived exosomes significantly increase SIRT1 levels, enhance the production of mitochondrial biogenesis-related factors, and inhibit astrocyte activation, but do not suppress amyloid-β production. Thus, neural stem cell-derived exosomes may be a useful therapeutic strategy for Alzheimer’s disease that activates the SIRT1-PGC1α signaling pathway and increases NRF1 and COXIV synthesis to improve mitochondrial biogenesis. In addition, we showed that the spatial distribution of mitochondrial biogenesis-related factors is disrupted in Alzheimer’s disease, and that neural stem cell-derived exosome treatment can reverse this effect, indicating that neural stem cell-derived exosomes promote mitochondrial biogenesis.
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    Sorl1 knockout inhibits expression of brain-derived neurotrophic factor: involvement in the development of late-onset Alzheimer’s disease
    Mingri Zhao, Xun Chen, Jiangfeng Liu, Yanjin Feng, Chen Wang, Ting Xu, Wanxi Liu, Xionghao Liu, Mujun Liu, Deren Hou
    2024, 19 (7):  1602-1607.  doi: 10.4103/1673-5374.387975
    Abstract ( 260 )   PDF (4329KB) ( 88 )   Save
    Sortilin-related receptor 1 (SORL1) is a critical gene associated with late-onset Alzheimer’s disease. SORL1 contributes to the development and progression of this neurodegenerative condition by affecting the transport and metabolism of intracellular β-amyloid precursor protein. To better understand the underlying mechanisms of SORL1 in the pathogenesis of late-onset Alzheimer’s disease, in this study, we established a mouse model of Sorl1 gene knockout using clustered regularly interspaced short palindromic repeats-associated protein 9 technology. We found that Sorl1-knockout mice displayed deficits in learning and memory. Furthermore, the expression of brain-derived neurotrophic factor was significantly downregulated in the hippocampus and cortex, and amyloid β-protein deposits were observed in the brains of Sorl1-knockout mice. In vitro, hippocampal neuronal cell synapses from homozygous Sorl1-knockout mice were impaired. The expression of synaptic proteins, including Drebrin and NR2B, was significantly reduced, and also their colocalization. Additionally, by knocking out the Sorl1 gene in N2a cells, we found that expression of the N-methyl-D-aspartate receptor, NR2B, and cyclic adenosine monophosphate-response element binding protein was also inhibited. These findings suggest that SORL1 participates in the pathogenesis of late-onset Alzheimer’s disease by regulating the N-methyl-D-aspartate receptor NR2B/cyclic adenosine monophosphate-response element binding protein signaling axis.
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    Homer1a reduces inflammatory response after retinal ischemia/reperfusion injury
    Yanan Dou, Xiaowei Fei, Xin He, Yu Huan, Jialiang Wei, Xiuquan Wu, Weihao Lyu, Zhou Fei, Xia Li, Fei Fei
    2024, 19 (7):  1608-1617.  doi: 10.4103/1673-5374.386490
    Abstract ( 139 )   PDF (7972KB) ( 27 )   Save
    Elevated intraocular pressure (IOP) is one of the causes of retinal ischemia/reperfusion injury, which results in NLRP3 inflammasome activation and leads to visual damage. Homer1a is reported to play a protective role in neuroinflammation in the cerebrum. However, the effects of Homer1a on NLRP3 inflammasomes in retinal ischemia/reperfusion injury caused by elevated IOP remain unknown. In our study, animal models were constructed using C57BL/6J and Homer1flox/–/Homer1a+/–/Nestin-Cre+/– mice with elevated IOP-induced retinal ischemia/reperfusion injury. For in vitro experiments, the oxygen-glucose deprivation/reperfusion injury model was constructed with Müller cells. We found that Homer1a overexpression ameliorated the decreases in retinal thickness and Müller cell viability after ischemia/reperfusion injury. Furthermore, Homer1a knockdown promoted NF-κB P65Ser536 activation via caspase-8, NF-κB P65 nuclear translocation, NLRP3 inflammasome formation, and the production and processing of interleukin-1β and interleukin-18. The opposite results were observed with Homer1a overexpression. Finally, the combined administration of Homer1a protein and JSH-23 significantly inhibited the reduction in retinal thickness in Homer1flox/–/Homer1a+/–/Nestin-Cre+/– mice and apoptosis in Müller cells after ischemia/reperfusion injury. Taken together, these studies demonstrate that Homer1a exerts protective effects on retinal tissue and Müller cells via the caspase-8/NF-κB P65/NLRP3 pathway after I/R injury.
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    Melatonin improves synapse development by PI3K/Akt signaling in a mouse model of autism spectrum disorder
    Luyi Wang, Man Xu, Yan Wang, Feifei Wang, Jing Deng, Xiaoya Wang, Yu Zhao, Ailing Liao, Feng Yang, Shali Wang, Yingbo Li
    2024, 19 (7):  1618-1624.  doi: 10.4103/1673-5374.387973
    Abstract ( 167 )   PDF (3317KB) ( 291 )   Save
    Autism spectrum disorders are a group of neurodevelopmental disorders involving more than 1100 genes, including Ctnnd2 as a candidate gene. Ctnnd2 knockout mice, serving as an animal model of autism, have been demonstrated to exhibit decreased density of dendritic spines. The role of melatonin, as a neurohormone capable of effectively alleviating social interaction deficits and regulating the development of dendritic spines, in Ctnnd2 deletion-induced nerve injury remains unclear. In the present study, we discovered that the deletion of exon 2 of the Ctnnd2 gene was linked to social interaction deficits, spine loss, impaired inhibitory neurons, and suppressed phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signal pathway in the prefrontal cortex. Our findings demonstrated that the long-term oral administration of melatonin for 28 days effectively alleviated the aforementioned abnormalities in Ctnnd2 gene-knockout mice. Furthermore, the administration of melatonin in the prefrontal cortex was found to improve synaptic function and activate the PI3K/Akt signal pathway in this region. The pharmacological blockade of the PI3K/Akt signal pathway with a PI3K/Akt inhibitor, wortmannin, and melatonin receptor antagonists, luzindole and 4-phenyl-2-propionamidotetralin, prevented the melatonin-induced enhancement of GABAergic synaptic function. These findings suggest that melatonin treatment can ameliorate GABAergic synaptic function by activating the PI3K/Akt signal pathway, which may contribute to the improvement of dendritic spine abnormalities in autism spectrum disorders.
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