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Beeraka NM, Vikram PRH, Greeshma MV, Uthaiah CA, Huria T, Liu J, Kumar P, Nikolenko VN, Bulygin KV, Sinelnikov MY, Sukocheva O, Fan R. Recent Investigations on Neurotransmitters' Role in Acute White Matter Injury of Perinatal Glia and Pharmacotherapies-Glia Dynamics in Stem Cell Therapy. Mol Neurobiol 2022; 59:2009-2026. [PMID: 35041139 DOI: 10.1007/s12035-021-02700-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 12/10/2021] [Indexed: 02/05/2023]
Abstract
Periventricular leukomalacia (PVL) and cerebral palsy are two neurological disease conditions developed from the premyelinated white matter ischemic injury (WMI). The significant pathophysiology of these diseases is accompanied by the cognitive deficits due to the loss of function of glial cells and axons. White matter makes up 50% of the brain volume consisting of myelinated and non-myelinated axons, glia, blood vessels, optic nerves, and corpus callosum. Studies over the years have delineated the susceptibility of white matter towards ischemic injury especially during pregnancy (prenatal, perinatal) or immediately after child birth (postnatal). Impairment in membrane depolarization of neurons and glial cells by ischemia-invoked excitotoxicity is mediated through the overactivation of NMDA receptors or non-NMDA receptors by excessive glutamate influx, calcium, or ROS overload and has been some of the well-studied molecular mechanisms conducive to the injury of white matter. Expression of glutamate receptors (GluR) and transporters (GLT1, EACC1, and GST) has significant influence in glial and axonal-mediated injury of premyelinated white matter during PVL and cerebral palsy. Predominantly, the central premyelinated axons express extensive levels of functional NMDA GluR receptors to confer ischemic injury to premyelinated white matter which in turn invoke defects in neural plasticity. Several underlying molecular mechanisms are yet to be unraveled to delineate the complete pathophysiology of these prenatal neurological diseases for developing the novel therapeutic modalities to mitigate pathophysiology and premature mortality of newborn babies. In this review, we have substantially discussed the above multiple pathophysiological aspects of white matter injury along with glial dynamics, and the pharmacotherapies including recent insights into the application of MSCs as therapeutic modality in treating white matter injury.
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Affiliation(s)
- Narasimha M Beeraka
- Cancer Center, Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, People's Republic of China
- Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR), Department of Biochemistry, JSS Medical College, JSS Academy of Higher Education and Research (JSS AHER), Mysuru, Karnataka, India
- Department of Human Anatomy, I. M. Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia
| | - P R Hemanth Vikram
- Department of Pharmaceutical Chemistry, JSS Pharmacy College, Mysuru, Karnataka, India
| | - M V Greeshma
- Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR), Department of Biochemistry, JSS Medical College, JSS Academy of Higher Education and Research (JSS AHER), Mysuru, Karnataka, India
| | - Chinnappa A Uthaiah
- Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR), Department of Biochemistry, JSS Medical College, JSS Academy of Higher Education and Research (JSS AHER), Mysuru, Karnataka, India
| | - Tahani Huria
- Faculty of Medicine, Benghazi University, Benghazi, Libya
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, LE1 7RH, UK
| | - Junqi Liu
- Cancer Center, Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, People's Republic of China
| | - Pramod Kumar
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER-Guwahati), SilaKatamur (Halugurisuk), Changsari, Kamrup, 781101, Assam, India
| | - Vladimir N Nikolenko
- Department of Human Anatomy, I. M. Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia
- Department of Normal and Topographic Anatomy, Faculty of Fundamental Medicine, Lomonosov Moscow State University, Moscow, Russia
| | - Kirill V Bulygin
- Department of Human Anatomy, I. M. Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia
| | - Mikhail Y Sinelnikov
- Department of Human Anatomy, I. M. Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia
- Research Institute of Human Morphology, 3 Tsyurupy Street, Moscow, 117418, Russian Federation
| | - Olga Sukocheva
- Discipline of Health Sciences, College of Nursing and Health Sciences, Flinders University, Bedford Park, South Australia, 5042, Australia
| | - Ruitai Fan
- Cancer Center, Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, People's Republic of China.
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Beeraka NM, Avila-Rodriguez MF, Aliev G. Recent Reports on Redox Stress-Induced Mitochondrial DNA Variations, Neuroglial Interactions, and NMDA Receptor System in Pathophysiology of Schizophrenia. Mol Neurobiol 2022; 59:2472-2496. [PMID: 35083660 DOI: 10.1007/s12035-021-02703-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/14/2021] [Indexed: 10/19/2022]
Abstract
Schizophrenia (SZ) is a chronic psychiatric disorder affecting several people worldwide. Mitochondrial DNA (mtDNA) variations could invoke changes in the OXPHOS system, calcium buffering, and ROS production, which have significant implications for glial cell survival during SZ. Oxidative stress has been implicated in glial cells-mediated pathogenesis of SZ; the brain comparatively more prone to oxidative damage through NMDAR. A confluence of scientific evidence points to mtDNA alterations, Nrf2 signaling, dynamic alterations in dorsolateral prefrontal cortex (DLPFC), and provocation of oxidative stress that enhance pathophysiology of SZ. Furthermore, the alterations in excitatory signaling related to NMDAR signaling were particularly reported for SZ pathophysiology. Current review reported the recent evidence for the role of mtDNA variations and oxidative stress in relation to pathophysiology of SZ, NMDAR hypofunction, and glutathione deficiency. NMDAR system is influenced by redox dysregulation in oxidative stress, inflammation, and antioxidant mediators. Several studies have demonstrated the relationship of these variables on severity of pathophysiology in SZ. An extensive literature search was conducted using Medline, PubMed, PsycINFO, CINAHL PLUS, BIOSIS Preview, Google scholar, and Cochrane databases. We summarize consistent evidence pointing out a plausible model that may elucidate the crosstalk between mtDNA alterations in glial cells and redox dysregulation during oxidative stress and the perturbation of NMDA neurotransmitter system during current therapeutic modalities for the SZ treatment. This review can be beneficial for the development of promising novel diagnostics, and therapeutic modalities by ascertaining the mtDNA variations, redox state, and efficacy of pharmacological agents to mitigate redox dysregulation and augment NMDAR function to treat cognitive and behavioral symptoms in SZ.
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Affiliation(s)
- Narasimha M Beeraka
- Department of Human Anatomy, I M Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia.
| | - Marco F Avila-Rodriguez
- Faculty of Health Sciences, Department of Clinical Sciences, Barrio Santa Helena, University of Tolima, 730006, Ibagué, Colombia
| | - Gjumrakch Aliev
- Department of Human Anatomy, I M Sechenov First Moscow State Medical University (Sechenov University), St. Trubetskaya, 8, bld. 2, Moscow, 119991, Russia.,Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432, Russia.,Research Institute of Human Morphology, 3 Tsyurupy Street, Moscow, 117418, Russia.,GALLY International Research Institute, 7733 Louis Pasteur Drive, #330, San Antonio, TX, 78229, USA
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Yang F, Li Y, Sheng X, Liu Y. Paeoniflorin treatment regulates TLR4/NF-κB signaling, reduces cerebral oxidative stress and improves white matter integrity in neonatal hypoxic brain injury. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2021; 25:97-109. [PMID: 33602880 PMCID: PMC7893490 DOI: 10.4196/kjpp.2021.25.2.97] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 02/04/2023]
Abstract
Neonatal hypoxia/ischemia (H/I), injures white matter, results in neuronal loss, disturbs myelin formation, and neural network development. Neuroinflammation and oxidative stress have been reported in neonatal hypoxic brain injuries. We investigated whether Paeoniflorin treatment reduced H/I-induced inflammation and oxidative stress and improved white matter integrity in a neonatal rodent model. Seven-day old Sprague–Dawley pups were exposed to H/I. Paeoniflorin (6.25, 12.5, or 25 mg/kg body weight) was administered every day via oral gavage from postpartum day 3 (P3) to P14, and an hour before induction of H/I. Pups were sacrificed 24 h (P8) and 72 h (P10) following H/I. Paeoniflorin reduced the apoptosis of neurons and attenuated cerebral infarct volume. Elevated expression of cleaved caspase-3 and Bad were regulated. Paeoniflorin decreased oxidative stress by lowering levels of malondialdehyde and reactive oxygen species generation and while, and it enhanced glutathione content. Microglial activation and the TLR4/NF-κB signaling were significantly down-regulated. The degree of inflammatory mediators (interleukin 1β and tumor necrosis factor-α) were reduced. Paeoniflorin markedly prevented white matter injury via improving expression of myelin binding protein and increasing O1-positive olidgodendrocyte and O4-positive oligodendrocyte counts. The present investigation demonstrates the potent protective efficiency of paeoniflorin supplementation against H/I-induced brain injury by effectually preventing neuronal loss, microglial activation, and white matter injury via reducing oxidative stress and inflammatory pathways.
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Affiliation(s)
- Fan Yang
- Department of Clinical Nutrition, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, Yunnan, China
| | - Ya Li
- Department of Clinical Laboratory, The First Affiliated Hospital of Kunming Medical University, Kunming 650032, Yunnan, China.,Yunnan Institute of Laboratory Diagnosis, Kunming 650032, Yunnan, China.,Yunnan Key Laboratory of Laboratory Medicine, Kunming 650032, Yunnan, China
| | - Xun Sheng
- School of Stomatology, Kunming Medical University, Kunming 650032, Yunnan, China
| | - Yu Liu
- Department of Pharmacy, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, Yunnan, China
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Can miRNAs Be Considered as Diagnostic and Therapeutic Molecules in Ischemic Stroke Pathogenesis?-Current Status. Int J Mol Sci 2020; 21:ijms21186728. [PMID: 32937836 PMCID: PMC7555634 DOI: 10.3390/ijms21186728] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/12/2022] Open
Abstract
Ischemic stroke is one of the leading causes of death worldwide. Clinical manifestations of stroke are long-lasting and causing economic burden on the patients and society. Current therapeutic modalities to treat ischemic stroke (IS) are unsatisfactory due to the intricate pathophysiology and poor functional recovery of brain cellular compartment. MicroRNAs (miRNA) are endogenously expressed small non-coding RNA molecules, which can act as translation inhibitors and play a pivotal role in the pathophysiology associated with IS. Moreover, miRNAs may be used as potential diagnostic and therapeutic tools in clinical practice; yet, the complete role of miRNAs is enigmatic during IS. In this review, we explored the role of miRNAs in the regulation of stroke risk factors viz., arterial hypertension, metabolic disorders, and atherosclerosis. Furthermore, the role of miRNAs were reviewed during IS pathogenesis accompanied by excitotoxicity, oxidative stress, inflammation, apoptosis, angiogenesis, neurogenesis, and Alzheimer's disease. The functional role of miRNAs is a double-edged sword effect in cerebral ischemia as they could modulate pathological mechanisms associated with risk factors of IS. miRNAs pertaining to IS pathogenesis could be potential biomarkers for stroke; they could help researchers to identify a particular stroke type and enable medical professionals to evaluate the severity of brain injury. Thus, ascertaining the role of miRNAs may be useful in deciphering their diagnostic role consequently it is plausible to envisage a suitable therapeutic modality against IS.
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Xu MY, Wang YF, Wei PJ, Gao YQ, Zhang WT. Hypoxic preconditioning improves long-term functional outcomes after neonatal hypoxia-ischemic injury by restoring white matter integrity and brain development. CNS Neurosci Ther 2019; 25:734-747. [PMID: 30689302 PMCID: PMC6515700 DOI: 10.1111/cns.13102] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/16/2022] Open
Abstract
Aims Neonatal hypoxia–ischemia (H/I) results in gray and white matter injury, characterized by neuronal loss, failure of neural network formation, retarded myelin formation, and abnormal accumulation of oligodendrocyte progenitor cells (OPCs). These changes lead to severe neurological deficits and mortality. Sublethal hypoxic preconditioning (HPC) can protect the developing brain against H/I. However, limited evidence is available concerning its effect on white matter injury. Methods In this study, P6 neonatal Sprague‐Dawley rats were subjected to normoxic (21% O2) or HPC (7.8% O2) for 3 hours followed 24 hours later by H/I brain injury. Neurological deficits were assessed by gait, righting reflex, foot fault, and Morris water maze tests. Compound action potential of the corpus callosum was recorded 35 days after surgery, and the correlation between axon myelination and neurological function was determined. Results Hypoxic preconditioning significantly attenuated H/I brain injury at 7 days and remarkably improved both sensorimotor and cognitive functional performances up to 35 days after H/I. HPC‐afforded improvement in long‐term neurological outcomes was attributable, at least in part, to restoration of the differentiation and maturation capacity in oligodendrocyte progenitor cells, amelioration of microglia/macrophage activation and neuroinflammation, and continuation of brain development after H/I. Conclusions Hypoxic preconditioning restores white matter repair, development, and functional integrity in developing brain after H/I brain injury.
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Affiliation(s)
- Ming-Yue Xu
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Yang-Fan Wang
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Peng-Ju Wei
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Yan-Qin Gao
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Wen-Ting Zhang
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
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Cai W, Yang T, Liu H, Han L, Zhang K, Hu X, Zhang X, Yin KJ, Gao Y, Bennett MVL, Leak RK, Chen J. Peroxisome proliferator-activated receptor γ (PPARγ): A master gatekeeper in CNS injury and repair. Prog Neurobiol 2017; 163-164:27-58. [PMID: 29032144 DOI: 10.1016/j.pneurobio.2017.10.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/06/2017] [Accepted: 10/08/2017] [Indexed: 01/06/2023]
Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) is a widely expressed ligand-modulated transcription factor that governs the expression of genes involved in inflammation, redox equilibrium, trophic factor production, insulin sensitivity, and the metabolism of lipids and glucose. Synthetic PPARγ agonists (e.g. thiazolidinediones) are used to treat Type II diabetes and have the potential to limit the risk of developing brain injuries such as stroke by mitigating the influence of comorbidities. If brain injury develops, PPARγ serves as a master gatekeeper of cytoprotective stress responses, improving the chances of cellular survival and recovery of homeostatic equilibrium. In the acute injury phase, PPARγ directly restricts tissue damage by inhibiting the NFκB pathway to mitigate inflammation and stimulating the Nrf2/ARE axis to neutralize oxidative stress. During the chronic phase of acute brain injuries, PPARγ activation in injured cells culminates in the repair of gray and white matter, preservation of the blood-brain barrier, reconstruction of the neurovascular unit, resolution of inflammation, and long-term functional recovery. Thus, PPARγ lies at the apex of cell fate decisions and exerts profound effects on the chronic progression of acute injury conditions. Here, we review the therapeutic potential of PPARγ in stroke and brain trauma and highlight the novel role of PPARγ in long-term tissue repair. We describe its structure and function and identify the genes that it targets. PPARγ regulation of inflammation, metabolism, cell fate (proliferation/differentiation/maturation/survival), and many other processes also has relevance to other neurological diseases. Therefore, PPARγ is an attractive target for therapies against a number of progressive neurological disorders.
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Affiliation(s)
- Wei Cai
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Tuo Yang
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Huan Liu
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Lijuan Han
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Kai Zhang
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Xiaoming Hu
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA; State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Fudan University, Shanghai 200032, China; Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh PA, USA
| | - Xuejing Zhang
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Ke-Jie Yin
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Yanqin Gao
- State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Michael V L Bennett
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, School of Pharmacy, Duquesne University, Pittsburgh, PA 15282, USA.
| | - Jun Chen
- Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA; State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Fudan University, Shanghai 200032, China; Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh PA, USA.
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Kaur C, Rathnasamy G, Ling EA. Biology of Microglia in the Developing Brain. J Neuropathol Exp Neurol 2017; 76:736-753. [PMID: 28859332 DOI: 10.1093/jnen/nlx056] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Microglia exist in different morphological forms in the developing brain. They show a small cell body with scanty cytoplasm with many branching processes in the grey matter of the developing brain. However, in the white matter such as the corpus callosum where the unmyelinated axons are loosely organized, they appear in an amoeboid form having a round cell body endowed with copious cytoplasm rich in organelles. The amoeboid cells eventually transform into ramified microglia in the second postnatal week when the tissue becomes more compact with the onset of myelination. Microglia serve as immunocompetent macrophages that act as neuropathology sensors to detect and respond swiftly to subtle changes in the brain tissues in pathological conditions. Microglial functions are broadly considered as protective in the normal brain development as they phagocytose dead cells and sculpt neuronal connections by pruning excess axons and synapses. They also secrete a number of trophic factors such as insulin-like growth factor-1 and transforming growth factor-β among many others that are involved in neuronal and oligodendrocyte survival. On the other hand, microglial cells when activated produce a plethora of molecules such as proinflammatory cytokines, chemokines, reactive oxygen species, and nitric oxide that are implicated in the pathogenesis of many pathological conditions such as epilepsy, cerebral palsy, autism, and perinatal hypoxic-ischemic brain injury. Although many studies have investigated the origin and functions of the microglia in the developing brain, in-depth in vivo studies along with analysis of their transcriptome and epigenetic changes need to be undertaken to elucidate their full potential be it protective or neurotoxic. This would lead to a better understanding of their roles in the healthy and diseased developing brain and advancement of therapeutic strategies to target microglia-mediated neurotoxicity.
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Affiliation(s)
- Charanjit Kaur
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Gurugirijha Rathnasamy
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Eng-Ang Ling
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
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Baltan S. Age-specific localization of NMDA receptors on oligodendrocytes dictates axon function recovery after ischemia. Neuropharmacology 2015; 110:626-632. [PMID: 26407763 DOI: 10.1016/j.neuropharm.2015.09.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 08/18/2015] [Accepted: 09/12/2015] [Indexed: 11/26/2022]
Abstract
Oligodendrocytes and axons are the main targets of an ischemic white matter injury and the resultant loss of axon function underlies the clinical disability in patients who survive a stroke. The cellular mechanisms of ischemic injury change as a function of age in concordance with age-mediated structural changes in white matter. Shorter periods of injury cause rapid and robust loss of axon function together with widespread oligodendrocyte death. While blockade of NMDA receptors fails to benefit axon function, removal of extracellular Ca2+ during ischemia remarkably promotes axon function recovery in young white matter. However, these same approaches hinder axon function recovery and fail to protect oligodendrocytes in aging white matter. The obligatory GluN1 subunit of the NMDA receptor exhibits an age-specific expression pattern such that in young adult white matter, it is mostly localized on oligodendrocyte cell bodies, while in aging white matter, it is also observed on myelin processes. This age-dependent re-localization and redistribution pattern mimics GluN1 expression observed during development, but in reverse order. During development, GluN1 immunoreactivity traffics from astrocytes at postnatal day 4-11 (P4-11) to myelin processes at P12-18 and to oligodendrocytes cell bodies at P19-21. Although immature axons are more resistant to ischemia, blockade of NMDA receptors during ischemia at P4-11 and P12-18 worsens axon function recovery and fails to benefit axons at P19-21. Thus, age-specific expression patterns of NMDA receptor localization may seem to modulate the plasticity of oligodendrocytes and myelin in response to ischemia as a function of age in white matter. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.
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Affiliation(s)
- Selva Baltan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA.
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Fern R. Ischemic tolerance in pre-myelinated white matter: the role of astrocyte glycogen in brain pathology. J Cereb Blood Flow Metab 2015; 35:951-8. [PMID: 25669910 PMCID: PMC4640254 DOI: 10.1038/jcbfm.2015.3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/15/2014] [Accepted: 12/17/2014] [Indexed: 11/09/2022]
Abstract
In isolated white matter, ischemic tolerance changes dramatically in the period immediately before the onset of myelination. In the absence of an extrinsic energy source, postnatal day 0 to 2 (P0 to P2) white matter axons are here shown to maintain excitability for over twice as long as axons >P2, a differential that was dependent on glycogen metabolism. Prolonged withdrawal of extrinsic energy supply tended to spare axons in zones around astrocytes, which are shown to be the sole repository for glycogen particles in developing white matter. Analysis of mitochondrial volume fraction revealed that neither axons nor astrocytes had a low metabolic rate in neonatal white matter, while oligodendroglia at older ages had an elevated metabolism. The astrocyte population is established early in neural development, and exhibits reduced cell density as maturation progresses and white matter expands. The findings show that this event establishes the necessary conditions for ischemia sensitivity in white matter and indicates that astrocyte proximity may be significant for the survival of neuronal elements in conditions associated with compromised energy supply.
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Affiliation(s)
- Robert Fern
- Peninsula School of Medicine and Dentistry, University of Plymouth, Plymouth, UK
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