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Kula B, Antal B, Weistuch C, Gackière F, Barre A, Velado V, Hubbard JM, Kukley M, Mujica-Parodi LR, Smith NA. D-β-hydroxybutyrate stabilizes hippocampal CA3-CA1 circuit during acute insulin resistance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.23.554428. [PMID: 37662316 PMCID: PMC10473684 DOI: 10.1101/2023.08.23.554428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The brain primarily relies on glycolysis for mitochondrial respiration but switches to alternative fuels such as ketone bodies (KBs) when less glucose is available. Neuronal KB uptake, which does not rely on glucose transporter 4 (GLUT4) or insulin, has shown promising clinical applicability in alleviating the neurological and cognitive effects of disorders with hypometabolic components. However, the specific mechanisms by which such interventions affect neuronal functions are poorly understood. In this study, we pharmacologically blocked GLUT4 to investigate the effects of exogenous KB D-β-hydroxybutyrate (D-βHb) on mouse brain metabolism during acute insulin resistance (AIR). We found that both AIR and D-βHb had distinct impacts across neuronal compartments: AIR decreased synaptic activity and long-term potentiation (LTP) and impaired axonal conduction, synchronization, and action potential (AP) properties, while D-βHb rescued neuronal functions associated with axonal conduction, synchronization, and LTP.
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Affiliation(s)
- Bartosz Kula
- Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester, School of Medicine and Dentistry, Rochester, USA
| | - Botond Antal
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, USA
| | - Corey Weistuch
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Florian Gackière
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, Le Puy Ste Réparade, France
| | - Alexander Barre
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, Le Puy Ste Réparade, France
| | - Victor Velado
- Center for Neuroscience Research, Children’s National Research Institute, Children’s National Hospital, Washington D.C., USA
| | - Jeffrey M Hubbard
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, Le Puy Ste Réparade, France
| | - Maria Kukley
- Achucarro Basque Center for Neuroscience, Leioa, Spain
- Ikerbasque - Basque Foundation for Science, Bilbao, Spain
| | - Lilianne R Mujica-Parodi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, USA
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, USA
| | - Nathan A Smith
- Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester, School of Medicine and Dentistry, Rochester, USA
- Center for Neuroscience Research, Children’s National Research Institute, Children’s National Hospital, Washington D.C., USA
- George Washington University School of Medicine and Health Sciences, Washington D.C., USA
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2
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Kula B, Antal B, Weistuch C, Gackière F, Barre A, Velado V, Hubbard JM, Kukley M, Mujica-Parodi LR, Smith NA. D-ꞵ-hydroxybutyrate stabilizes hippocampal CA3-CA1 circuit during acute insulin resistance. PNAS NEXUS 2024; 3:pgae196. [PMID: 38818236 PMCID: PMC11138115 DOI: 10.1093/pnasnexus/pgae196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 05/06/2024] [Indexed: 06/01/2024]
Abstract
The brain primarily relies on glycolysis for mitochondrial respiration but switches to alternative fuels such as ketone bodies (KBs) when less glucose is available. Neuronal KB uptake, which does not rely on glucose transporter 4 (GLUT4) or insulin, has shown promising clinical applicability in alleviating the neurological and cognitive effects of disorders with hypometabolic components. However, the specific mechanisms by which such interventions affect neuronal functions are poorly understood. In this study, we pharmacologically blocked GLUT4 to investigate the effects of exogenous KB D-ꞵ-hydroxybutyrate (D-ꞵHb) on mouse brain metabolism during acute insulin resistance (AIR). We found that both AIR and D-ꞵHb had distinct impacts across neuronal compartments: AIR decreased synaptic activity and long-term potentiation (LTP) and impaired axonal conduction, synchronization, and action potential properties, while D-ꞵHb rescued neuronal functions associated with axonal conduction, synchronization, and LTP.
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Affiliation(s)
- Bartosz Kula
- Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Botond Antal
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
| | - Corey Weistuch
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Florian Gackière
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, 13610 Le Puy-Sainte-Réparade, France
| | - Alexander Barre
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, 13610 Le Puy-Sainte-Réparade, France
| | - Victor Velado
- Center for Neuroscience Research, Children’s National Research Institute, Children’s National Hospital, Washington, DC 20012, USA
| | - Jeffrey M Hubbard
- Neuroservices Alliance, Les Jardins de l’Entreprise, Quartier de le Confrérie, 13610 Le Puy-Sainte-Réparade, France
| | - Maria Kukley
- Achucarro Basque Center for Neuroscience, 48940 Leioa, Bizkaia, Spain
- Ikerbasque—Basque Foundation for Science, 48009 Bilbao, Spain
| | - Lilianne R Mujica-Parodi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nathan A Smith
- Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA
- Center for Neuroscience Research, Children’s National Research Institute, Children’s National Hospital, Washington, DC 20012, USA
- School of Medicine and Health Sciences, George Washington University, Washington, DC 20052, USA
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3
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Cerutti L, Brofiga M. Unraveling brain diseases: The promise of brain-on-a-chip models. J Neurosci Methods 2024; 405:110105. [PMID: 38460796 DOI: 10.1016/j.jneumeth.2024.110105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 02/23/2024] [Accepted: 03/03/2024] [Indexed: 03/11/2024]
Abstract
Brain disorders, encompassing a wide spectrum of neurological and psychiatric conditions, present a formidable challenge in modern medicine. Despite decades of research, the intricate complexity of the human brain still eludes comprehensive understanding, impeding the development of effective treatments. Recent advancements in microfluidics and tissue engineering have led to the development of innovative platforms known as "Brain-on-a-Chip" (BoC) i.e., advanced in vitro systems that aim to replicate the microenvironment of the brain with the highest possible fidelity. This technology offers a promising test-bed for studying brain disorders at the cellular and network levels, providing insights into disease mechanisms, drug screening, and, in perspective, the development of personalized therapeutic strategies. In this review, we provide an overview of the BoC models developed over the years to model and understand the onset and progression of some of the most severe neurological disorders in terms of incidence and debilitation (stroke, Parkinson's, Alzheimer's, and epilepsy). We also report some of the cutting-edge therapeutic approaches whose effects were evaluated by means of these technologies. Finally, we discuss potential challenges, and future perspectives of the BoC models.
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Affiliation(s)
- Letizia Cerutti
- Department of Informatics, Bioengineering, Robotics, and Systems Engineering (DIBIRS), University of Genova, Genova, Italy
| | - Martina Brofiga
- Department of Informatics, Bioengineering, Robotics, and Systems Engineering (DIBIRS), University of Genova, Genova, Italy; ScreenNeuroPharm s.r.l, Sanremo, Italy; Neurofacility, Istituto Italiano di Tecnologia, Genova, Italy.
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4
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Sharma B, Koren DT, Ghosh S. Nitric oxide modulates NMDA receptor through a negative feedback mechanism and regulates the dynamical behavior of neuronal postsynaptic components. Biophys Chem 2023; 303:107114. [PMID: 37832215 DOI: 10.1016/j.bpc.2023.107114] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/22/2023] [Accepted: 09/24/2023] [Indexed: 10/15/2023]
Abstract
Nitric oxide (NO) is known to be an important regulator of neurological processes in the central nervous system which acts directly on the presynaptic neuron and enhances the release of neurotransmitters like glutamate into the synaptic cleft. Calcium influx activates a cascade of biochemical reactions to influence the production of nitric oxide in the postsynaptic neuron. This has been modeled in the present work as a system of ordinary differential equations, to explore the dynamics of the interacting components and predict the dynamical behavior of the postsynaptic neuron. It has been hypothesized that nitric oxide modulates the NMDA receptor via a feedback mechanism and regulates the dynamic behavior of postsynaptic components. Results obtained by numerical analyses indicate that the biochemical system is stimulus-dependent and shows oscillations of calcium and other components within a limited range of concentration. Some of the parameters such as stimulus strength, extracellular calcium concentration, and rate of nitric oxide feedback are crucial for the dynamics of the components in the postsynaptic neuron.
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Affiliation(s)
- Bhanu Sharma
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India
| | | | - Subhendu Ghosh
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India.
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5
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Tortella L, Santini I, Lozano N, Kostarelos K, Cellot G, Ballerini L. Graphene Oxide Nanosheets Hamper Glutamate Mediated Excitotoxicity and Protect Neuronal Survival In An In vitro Stroke Model. Chemistry 2023; 29:e202301762. [PMID: 37706581 DOI: 10.1002/chem.202301762] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/06/2023] [Accepted: 09/13/2023] [Indexed: 09/15/2023]
Abstract
Small graphene oxide (s-GO) nanosheets reversibly downregulate central nervous system (CNS) excitatory synapses, with potential developments as future therapeutic tools to treat neuro-disorders characterized by altered glutamatergic transmission. Excitotoxicity, namely cell death triggered by exceeding ambient glutamate fueling over-activation of excitatory synapses, is a pathogenic mechanism shared by several neural diseases, from ischemic stroke to neurodegenerative disorders. In this work, CNS cultures were exposed to oxygen-glucose deprivation (OGD) to mimic ischemic stroke in vitro, and it is show that the delivery of s-GO following OGD, during the endogenous build-up of secondary damage and excitotoxicity, improved neuronal survival. In a different paradigm, excitotoxicity cell damage was reproduced through exogenous glutamate application, and s-GO co-treatment protected neuronal integrity, potentially by directly downregulating the synaptic over-activation brought about by exogenous glutamate. This proof-of-concept study suggests that s-GO may find novel applications in therapeutic developments for treating excitotoxicity-driven neural cell death.
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Affiliation(s)
- Lorenza Tortella
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34136, Trieste, Italy
| | - Irene Santini
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34136, Trieste, Italy
| | - Neus Lozano
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain
| | - Kostas Kostarelos
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain
- Nanomedicine Lab, and Faculty of Biology, Medicine & Health, The National Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Giada Cellot
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34136, Trieste, Italy
| | - Laura Ballerini
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34136, Trieste, Italy
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6
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Liu Y, Shuai K, Sun Y, Zhu L, Wu XM. Advances in the study of axon-associated vesicles. Front Mol Neurosci 2022; 15:1045778. [PMID: 36545123 PMCID: PMC9760877 DOI: 10.3389/fnmol.2022.1045778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022] Open
Abstract
The central nervous system is the most important and difficult to study system in the human body and is known for its complex functions, components, and mechanisms. Neurons are the basic cellular units realizing neural functions. In neurons, vesicles are one of the critical pathways for intracellular material transport, linking information exchanges inside and outside cells. The axon is a vital part of neuron since electrical and molecular signals must be conducted through axons. Here, we describe and explore the formation, trafficking, and sorting of cellular vesicles within axons, as well as related-diseases and practical implications. Furthermore, with deepening of understanding and the development of new approaches, accumulating evidence proves that besides signal transmission between synapses, the material exchange and vesicular transmission between axons and extracellular environment are involved in physiological processes, and consequently to neural pathology. Recent studies have also paid attention to axonal vesicles and their physiological roles and pathological effects on axons themselves. Therefore, this review mainly focuses on these two key nodes to explain the role of intracellular vesicles and extracellular vesicles migrated from cells on axons and neurons, providing innovative strategy for future researches.
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Affiliation(s)
- Yanling Liu
- Institute of Special Environmental Medicine, Nantong University, Nantong, Jiangsu, China
| | - Ke Shuai
- Institute of Special Environmental Medicine, Nantong University, Nantong, Jiangsu, China
| | - Yiyan Sun
- Institute of Special Environmental Medicine, Nantong University, Nantong, Jiangsu, China
| | - Li Zhu
- Institute of Special Environmental Medicine, Nantong University, Nantong, Jiangsu, China,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Xiao-Mei Wu
- Institute of Special Environmental Medicine, Nantong University, Nantong, Jiangsu, China,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China,*Correspondence: Xiao-Mei Wu,
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7
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Excitatory Synaptic Transmission in Ischemic Stroke: A New Outlet for Classical Neuroprotective Strategies. Int J Mol Sci 2022; 23:ijms23169381. [PMID: 36012647 PMCID: PMC9409263 DOI: 10.3390/ijms23169381] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/15/2022] [Accepted: 08/17/2022] [Indexed: 01/01/2023] Open
Abstract
Stroke is one of the leading causes of death and disability in the world, of which ischemia accounts for the majority. There is growing evidence of changes in synaptic connections and neural network functions in the brain of stroke patients. Currently, the studies on these neurobiological alterations mainly focus on the principle of glutamate excitotoxicity, and the corresponding neuroprotective strategies are limited to blocking the overactivation of ionic glutamate receptors. Nevertheless, it is disappointing that these treatments often fail because of the unspecificity and serious side effects of the tested drugs in clinical trials. Thus, in the prevention and treatment of stroke, finding and developing new targets of neuroprotective intervention is still the focus and goal of research in this field. In this review, we focus on the whole processes of glutamatergic synaptic transmission and highlight the pathological changes underlying each link to help develop potential therapeutic strategies for ischemic brain damage. These strategies include: (1) controlling the synaptic or extra-synaptic release of glutamate, (2) selectively blocking the action of the glutamate receptor NMDAR subunit, (3) increasing glutamate metabolism, and reuptake in the brain and blood, and (4) regulating the glutamate system by GABA receptors and the microbiota–gut–brain axis. Based on these latest findings, it is expected to promote a substantial understanding of the complex glutamate signal transduction mechanism, thereby providing excellent neuroprotection research direction for human ischemic stroke (IS).
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8
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Lujan BJ, Singh M, Singh A, Renden RB. Developmental shift to mitochondrial respiration for energetic support of sustained transmission during maturation at the calyx of Held. J Neurophysiol 2021; 126:976-996. [PMID: 34432991 PMCID: PMC8560424 DOI: 10.1152/jn.00333.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 11/24/2022] Open
Abstract
A considerable amount of energy is expended following presynaptic activity to regenerate electrical polarization and maintain efficient release and recycling of neurotransmitter. Mitochondria are the major suppliers of neuronal energy, generating ATP via oxidative phosphorylation. However, the specific utilization of energy from cytosolic glycolysis rather than mitochondrial respiration at the presynaptic terminal during synaptic activity remains unclear and controversial. We use a synapse specialized for high-frequency transmission in mice, the calyx of Held, to test the sources of energy used to maintain energy during short activity bursts (<1 s) and sustained neurotransmission (30-150 s). We dissect the role of presynaptic glycolysis versus mitochondrial respiration by acutely and selectively blocking these ATP-generating pathways in a synaptic preparation where mitochondria and synaptic vesicles are prolific, under near-physiological conditions. Surprisingly, if either glycolysis or mitochondrial ATP production is intact, transmission during repetitive short bursts of activity is not affected. In slices from young animals before the onset of hearing, where the synapse is not yet fully specialized, both glycolytic and mitochondrial ATP production are required to support sustained, high-frequency neurotransmission. In mature synapses, sustained transmission relies exclusively on mitochondrial ATP production supported by bath lactate, but not glycolysis. At both ages, we observe that action potential propagation begins to fail before defects in synaptic vesicle recycling. Our data describe a specific metabolic profile to support high-frequency information transmission at the mature calyx of Held, shifting during postnatal synaptic maturation from glycolysis to rely on monocarboxylates as a fuel source.NEW & NOTEWORTHY We dissect the role of presynaptic glycolysis versus mitochondrial respiration in supporting high-frequency neurotransmission, by acutely blocking these ATP-generating pathways at a synapse tuned for high-frequency transmission. We find that massive energy expenditure is required to generate failure when only one pathway is inhibited. Action potential propagation is lost before impaired synaptic vesicle recycling. Synaptic transmission is exclusively dependent on oxidative phosphorylation in mature synapses, indicating presynaptic glycolysis may be dispensable for ATP maintenance.
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Affiliation(s)
- Brendan J Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Mahendra Singh
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Abhyudai Singh
- Electrical & Computer Engineering, University of Delaware, Newark, Delaware
| | - Robert B Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
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Wang Y, Xu L, Liu MZ, Hu DD, Fang F, Xu DJ, Zhang R, Hua XX, Li JB, Zhang L, Huang LN, Mu D. Norepinephrine modulates wakefulness via α1 adrenoceptors in paraventricular thalamic nucleus. iScience 2021; 24:103015. [PMID: 34522858 PMCID: PMC8426266 DOI: 10.1016/j.isci.2021.103015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/10/2021] [Accepted: 08/18/2021] [Indexed: 11/26/2022] Open
Abstract
Norepinephrine (NE) neurons in the locus coeruleus (LC) play key roles in modulating sleep and wakefulness. Recent studies have revealed that the paraventricular thalamic nucleus (PVT) is a critical wakefulness-controlling nucleus in mice. However, the effects of NE on PVT neurons remain largely unknown. Here, we investigated the mechanisms of NE modulating wakefulness in the PVT by using viral tracing, behavioral tests, slice electrophysiology, and optogenetics techniques. We found that the PVT-projecting LC neurons had few collateral projections to other brain nuclei. Behavioral tests showed that specific activation of the LC-PVT projections or microinjection of NE into the PVT accelerated emergence from general anesthesia and enhanced locomotion activity. Moreover, brain slice recording results indicated that NE increased the activity of the PVT neurons mainly by increasing the frequency of spontaneous excitatory postsynaptic currents via α1 adrenoceptors. Thus, our results demonstrate that NE modulates wakefulness via α1 adrenoceptors in the PVT.
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Affiliation(s)
- Yan Wang
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
| | - Ling Xu
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
| | - Ming-Zhe Liu
- Department of Respiratory, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Dan-Dan Hu
- Tongji University School of Medicine, Shanghai, China
| | - Fang Fang
- Department of Endocrinology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Dao-Jie Xu
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Rui Zhang
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
| | - Xiao-Xiao Hua
- Tongji University School of Medicine, Shanghai, China
| | - Jin-Bao Li
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
| | - Ling Zhang
- Tongji University School of Medicine, Shanghai, China
| | - Li-Na Huang
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
| | - Di Mu
- Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, No. 650 Xin Song Jiang Road, Shanghai 201620, China
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McCarty MF, Lerner A. Nutraceutical induction and mimicry of heme oxygenase activity as a strategy for controlling excitotoxicity in brain trauma and ischemic stroke: focus on oxidative stress. Expert Rev Neurother 2020; 21:157-168. [PMID: 33287596 DOI: 10.1080/14737175.2021.1861940] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Introduction: Ischemic stroke and traumatic brain injury are leading causes of acute mortality, and in the longer run, major causes of significant mental and physical impairment. Most of the brain neuronal cell death in the minutes and hours following an ischemic stroke or brain trauma is mediated by the process of excitotoxicity, in which sustained elevations of extracellular glutamate, reflecting a failure of ATP-dependent mechanism which sequester glutamate in neurons and astrocytes, drive excessive activation of NMDA receptors. Areas covered: A literature search was undertaken to clarify the molecular mechanisms whereby excessive NMDA activation leads to excitotoxic neuronal death, and to determine what safe nutraceutical agents might have practical potential for rescuing at-risk neurons by intervening in these mechanisms. Expert opinion: Activation of both NADPH oxidase and neuronal nitric oxide synthase in the microenvironment of activated NMDA receptors drives production of superoxide and highly toxic peroxynitrite. This leads to excessive activation of PARP and p38 MAP kinase, mitochondrial dysfunction, and subsequent neuronal death. Heme oxygenase-1 (HO-1) induction offers protection via inhibition of NADPH oxidase and promotion of cGMP generation. Phase 2-inductive nutraceuticals can induce HO-1, and other nutraceuticals can mimic the effects of its products biliverdin and carbon monoxide.
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Affiliation(s)
| | - Aaron Lerner
- Technion Israel Institute of Technology Ruth and Bruce Rappaport Faculty of Medicine- Research, Haifa, Israel (Retired)
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11
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Bednarczuk N, Milner A, Greenough A. The Role of Maternal Smoking in Sudden Fetal and Infant Death Pathogenesis. Front Neurol 2020; 11:586068. [PMID: 33193050 PMCID: PMC7644853 DOI: 10.3389/fneur.2020.586068] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022] Open
Abstract
Maternal smoking is a risk factor for both sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death syndrome (SIUDS). Both SIDS and SIUDS are more frequently observed in infants of smoking mothers. The global prevalence of smoking during pregnancy is 1.7% and up to 8.1% of women in Europe smoke during pregnancy and worldwide 250 million women smoke during pregnancy. Infants born to mothers who smoke have an abnormal response to hypoxia and hypercarbia and they also have reduced arousal responses. The harmful effects of tobacco smoke are mainly mediated by release of carbon monoxide and nicotine. Nicotine can enter the fetal circulation and affect multiple developing organs including the lungs, adrenal glands and the brain. Abnormalities in brainstem nuclei crucial to respiratory control, the cerebral cortex and the autonomic nervous system have been demonstrated. In addition, hypodevelopment of the intermediolateral nucleus in the spinal cord has been reported. It initiates episodic respiratory movements that facilitate lung development. Furthermore, abnormal maturation and transmitter levels in the carotid bodies have been described which would make infants more vulnerable to hypoxic challenges. Unfortunately, smoking cessation programs do not appear to have significantly reduced the number of pregnant women who smoke.
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Affiliation(s)
- Nadja Bednarczuk
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Anthony Milner
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Anne Greenough
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom.,The Asthma UK Centre for Allergic Mechanisms of Asthma, King's College London, London, United Kingdom.,National Institute for Health Research (NIHR) Biomedical Research Centre at Guy's & St Thomas' National Health Service (NHS) Foundation Trust and King's College London, London, United Kingdom
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12
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Shan W, Hu Y, Ding J, Yang X, Lou J, Du Q, Liao Q, Luo L, Xu J, Xie R. Advances in Ca 2+ modulation of gastrointestinal anion secretion and its dysregulation in digestive disorders (Review). Exp Ther Med 2020; 20:8. [PMID: 32934673 PMCID: PMC7471861 DOI: 10.3892/etm.2020.9136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Intracellular calcium (Ca2+) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca2+]cyt), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca2+]cyt in GI epithelial anion secretion. Ca2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl- channels, Ca2+-activated K+ channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO3- exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca2+-mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO3- and Cl- secretion. An increased understanding of the roles of Ca2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases.
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Affiliation(s)
- Weixi Shan
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Yanxia Hu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jianhong Ding
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xiaoxu Yang
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jun Lou
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qian Du
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qiushi Liao
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Lihong Luo
- Department of Oncology and Geriatrics, Traditional Chinese Medicine Hospital of Chishui City, Guizhou 564700, P.R. China
| | - Jingyu Xu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Rui Xie
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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13
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Transient Receptor Potential Melastatin 2 (TRPM2) Inhibition by Antioxidant, N-Acetyl-l-Cysteine, Reduces Global Cerebral Ischemia-Induced Neuronal Death. Int J Mol Sci 2020; 21:ijms21176026. [PMID: 32825703 PMCID: PMC7504640 DOI: 10.3390/ijms21176026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/14/2022] Open
Abstract
A variety of pathogenic mechanisms, such as cytoplasmic calcium/zinc influx, reactive oxygen species production, and ionic imbalance, have been suggested to play a role in cerebral ischemia induced neurodegeneration. During the ischemic state that occurs after stroke or heart attack, it is observed that vesicular zinc can be released into the synaptic cleft, and then translocated into the cytoplasm via various cation channels. Transient receptor potential melastatin 2 (TRPM2) is highly distributed in the central nervous system and has high sensitivity to oxidative damage. Several previous studies have shown that TRPM2 channel activation contributes to neuroinflammation and neurodegeneration cascades. Therefore, we examined whether anti-oxidant treatment, such as with N-acetyl-l-cysteine (NAC), provides neuroprotection via regulation of TRPM2, following global cerebral ischemia (GCI). Experimental animals were then immediately injected with NAC (150 mg/kg/day) for 3 and 7 days, before sacrifice. We demonstrated that NAC administration reduced activation of GCI-induced neuronal death cascades, such as lipid peroxidation, microglia and astroglia activation, free zinc accumulation, and TRPM2 over-activation. Therefore, modulation of the TRPM2 channel can be a potential therapeutic target to prevent ischemia-induced neuronal death.
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14
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Belov Kirdajova D, Kriska J, Tureckova J, Anderova M. Ischemia-Triggered Glutamate Excitotoxicity From the Perspective of Glial Cells. Front Cell Neurosci 2020; 14:51. [PMID: 32265656 PMCID: PMC7098326 DOI: 10.3389/fncel.2020.00051] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/21/2020] [Indexed: 12/21/2022] Open
Abstract
A plethora of neurological disorders shares a final common deadly pathway known as excitotoxicity. Among these disorders, ischemic injury is a prominent cause of death and disability worldwide. Brain ischemia stems from cardiac arrest or stroke, both responsible for insufficient blood supply to the brain parenchyma. Glucose and oxygen deficiency disrupts oxidative phosphorylation, which results in energy depletion and ionic imbalance, followed by cell membrane depolarization, calcium (Ca2+) overload, and extracellular accumulation of excitatory amino acid glutamate. If tight physiological regulation fails to clear the surplus of this neurotransmitter, subsequent prolonged activation of glutamate receptors forms a vicious circle between elevated concentrations of intracellular Ca2+ ions and aberrant glutamate release, aggravating the effect of this ischemic pathway. The activation of downstream Ca2+-dependent enzymes has a catastrophic impact on nervous tissue leading to cell death, accompanied by the formation of free radicals, edema, and inflammation. After decades of “neuron-centric” approaches, recent research has also finally shed some light on the role of glial cells in neurological diseases. It is becoming more and more evident that neurons and glia depend on each other. Neuronal cells, astrocytes, microglia, NG2 glia, and oligodendrocytes all have their roles in what is known as glutamate excitotoxicity. However, who is the main contributor to the ischemic pathway, and who is the unsuspecting victim? In this review article, we summarize the so-far-revealed roles of cells in the central nervous system, with particular attention to glial cells in ischemia-induced glutamate excitotoxicity, its origins, and consequences.
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Affiliation(s)
- Denisa Belov Kirdajova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia.,Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Jan Kriska
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia.,Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Jana Tureckova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia
| | - Miroslava Anderova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia.,Second Faculty of Medicine, Charles University, Prague, Czechia
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15
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Bragança B, Nogueira-Marques S, Ferreirinha F, Fontes-Sousa AP, Correia-de-Sá P. The Ionotropic P2X4 Receptor has Unique Properties in the Heart by Mediating the Negative Chronotropic Effect of ATP While Increasing the Ventricular Inotropy. Front Pharmacol 2019; 10:1103. [PMID: 31611793 PMCID: PMC6769074 DOI: 10.3389/fphar.2019.01103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/28/2019] [Indexed: 01/09/2023] Open
Abstract
Background: Mounting evidence indicate that reducing the sinoatrial node (SAN) activity may be a useful therapeutic strategy to control of heart failure. Purines, like ATP and its metabolite adenosine, consistently reduce the SAN spontaneous activity leading to negative cardiac chronotropy, with variable effects on the force of myocardial contraction (inotropy). Apart from adenosine A1 receptors, the human SAN expresses high levels of ATP-sensitive ionotropic P2X4 receptors (P2X4R), yet their cardiac role is unexplored. Methods: Here, we investigated the activity of P2 purinoceptors on isolated spontaneously beating atria (chronotropy) and on 2 Hz-paced right ventricular (RV, inotropy) strips from Wistar rats. Results: ATP (pEC 50 = 4.05) and its stable analogue ATPγS (pEC 50 = 4.69) concentration-dependently reduced atrial chronotropy. Inhibition of ATP breakdown into adenosine by NTPDases with POM-1 failed to modify ATP-induced negative chronotropy. The effect of ATP on atrial rate was attenuated by a broad-spectrum P2 antagonist, PPADS, as well as by 5-BDBD, which selectively blocks the P2X4R subtype; however, no effect was observed upon blocking the A1 receptor with DPCPX. The P2X4R positive allosteric modulator, ivermectin, increased the negative chronotropic response of ATP. Likewise, CTP, a P2X agonist that does not generate adenosine, replicated the P2X4R-mediated negative chronotropism of ATP. Inhibition of the Na+/Ca2+ exchanger (NCX) with KB-R7943 and ORM-10103, but not blockage of the HCN channel with ZD7288, mimicked the effect of the P2X4R blocker, 5-BDBD. In paced RV strips, ATP caused a mild negative inotropic effect, which magnitude was 2 to 3-fold increased by 5-BDBD and KB-R7943. Immunofluorescence confocal microscopy studies confirm that cardiomyocytes of the rat SAN and RV co-express P2X4R and NCX1 proteins. Conclusions: Data suggest that activation of ATP-sensitive P2X4R slows down heart rate by reducing the SAN activity while increasing the magnitude of ventricular contractions. The mechanism underlying the dual effect of ATP in the heart may involve inhibition of intracellular Ca2+-extrusion by bolstering NCX function in the reverse mode. Thus, targeting the P2X4R activation may create novel well-tolerated heart-rate lowering drugs with potential benefits in patients with deteriorated ventricular function.
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Affiliation(s)
- Bruno Bragança
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal.,Hospital Pedro Hispano, ULS Matosinhos, Matosinhos, Portugal
| | - Sílvia Nogueira-Marques
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Ana Patrícia Fontes-Sousa
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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16
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You J, Feng L, Bao L, Xin M, Ma D, Feng J. Potential Applications of Remote Limb Ischemic Conditioning for Chronic Cerebral Circulation Insufficiency. Front Neurol 2019; 10:467. [PMID: 31130914 PMCID: PMC6509171 DOI: 10.3389/fneur.2019.00467] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/17/2019] [Indexed: 12/12/2022] Open
Abstract
Chronic cerebral circulation insufficiency (CCCI) refers to a chronic decrease in cerebral blood perfusion, which may lead to cognitive impairment, psychiatric disorders such as depression, and acute ischemic stroke. Remote limb ischemic conditioning (RLIC), in which the limbs are subjected to a series of transient ischemic attacks, can activate multiple endogenous protective mechanisms to attenuate fatal ischemic injury to distant organs due to acute ischemia, such as ischemic stroke. Recent studies have also reported that RLIC can alleviate dysfunction in distant organs caused by chronic, non-fatal reductions in blood supply (e.g., CCCI). Indeed, research has indicated that RLIC may exert neuroprotective effects against CCCI through a variety of potential mechanisms, including attenuated glutamate excitotoxicity, improved endothelial function, increased cerebral blood flow, regulation of autophagy and immune responses, suppression of apoptosis, the production of protective humoral factors, and attenuated accumulation of amyloid-β. Verification of these findings is necessary to improve prognosis and reduce the incidence of acute ischemic stroke/cognitive impairment in patients with CCCI.
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Affiliation(s)
- Jiulin You
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Liangshu Feng
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Liyang Bao
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Meiying Xin
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Di Ma
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Jiachun Feng
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
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17
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Kim AY, Baik EJ. Glutamate Dehydrogenase as a Neuroprotective Target Against Neurodegeneration. Neurochem Res 2018; 44:147-153. [PMID: 29357018 DOI: 10.1007/s11064-018-2467-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/03/2018] [Accepted: 01/05/2018] [Indexed: 10/18/2022]
Abstract
Regulation of glutamate metabolism via glutamate dehydrogenase (GDH) might be the promising therapeutic approach for treating neurodegenerative disorders. In the central nervous system, glutamate functions both as a major excitatory neurotransmitter and as a key intermediate metabolite for neurons. GDH converts glutamate to α-ketoglutarate, which serves as a TCA cycle intermediate. Dysregulated GDH activity in the central nervous system is highly correlated with neurological disorders. Indeed, studies conducted with mutant mice and allosteric drugs have shown that deficient or overexpressed GDH activity in the brain can regulate whole body energy metabolism and affect early onset of Parkinson's disease, Alzheimer's disease, temporal lobe epilepsy, and spinocerebellar atrophy. Moreover, in strokes with excitotoxicity as the main pathophysiology, mice that overexpressed GDH exhibited smaller ischemic lesion than mice with normal GDH expression. In additions, GDH activators improve lesions in vivo by increasing α-ketoglutarate levels. In neurons exposed to an insult in vitro, enhanced GDH activity increases ATP levels. Thus, in an energy crisis, neuronal mitochondrial activity is improved and excitotoxic risk is reduced. Consequently, modulating GDH activity in energy-depleted conditions could be a sound strategy for maintaining the mitochondrial factory in neurons, and thus, protect against metabolic failure.
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Affiliation(s)
- A Young Kim
- Department of Physiology, Ajou University School of Medicine, Suwon, 16499, South Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 16499, South Korea
| | - Eun Joo Baik
- Department of Physiology, Ajou University School of Medicine, Suwon, 16499, South Korea. .,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 16499, South Korea.
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18
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Lujan B, Kushmerick C, Banerjee TD, Dagda RK, Renden R. Glycolysis selectively shapes the presynaptic action potential waveform. J Neurophysiol 2016; 116:2523-2540. [PMID: 27605535 DOI: 10.1152/jn.00629.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/05/2016] [Indexed: 11/22/2022] Open
Abstract
Mitochondria are major suppliers of cellular energy in neurons; however, utilization of energy from glycolysis vs. mitochondrial oxidative phosphorylation (OxPhos) in the presynaptic compartment during neurotransmission is largely unknown. Using presynaptic and postsynaptic recordings from the mouse calyx of Held, we examined the effect of acute selective pharmacological inhibition of glycolysis or mitochondrial OxPhos on multiple mechanisms regulating presynaptic function. Inhibition of glycolysis via glucose depletion and iodoacetic acid (1 mM) treatment, but not mitochondrial OxPhos, rapidly altered transmission, resulting in highly variable, oscillating responses. At reduced temperature, this same treatment attenuated synaptic transmission because of a smaller and broader presynaptic action potential (AP) waveform. We show via experimental manipulation and ion channel modeling that the altered AP waveform results in smaller Ca2+ influx, resulting in attenuated excitatory postsynaptic currents (EPSCs). In contrast, inhibition of mitochondria-derived ATP production via extracellular pyruvate depletion and bath-applied oligomycin (1 μM) had no significant effect on Ca2+ influx and did not alter the AP waveform within the same time frame (up to 30 min), and the resultant EPSC remained unaffected. Glycolysis, but not mitochondrial OxPhos, is thus required to maintain basal synaptic transmission at the presynaptic terminal. We propose that glycolytic enzymes are closely apposed to ATP-dependent ion pumps on the presynaptic membrane. Our results indicate a novel mechanism for the effect of hypoglycemia on neurotransmission. Attenuated transmission likely results from a single presynaptic mechanism at reduced temperature: a slower, smaller AP, before and independent of any effect on synaptic vesicle release or receptor activity.
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Affiliation(s)
- Brendan Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil; and
| | - Tania Das Banerjee
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Ruben K Dagda
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Robert Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada;
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19
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Berret E, Kim SE, Lee SY, Kushmerick C, Kim JH. Functional and structural properties of ion channels at the nerve terminal depends on compact myelin. J Physiol 2016; 594:5593-609. [PMID: 27168396 DOI: 10.1113/jp272205] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/04/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In the present study, we document the role of compact myelin in regulating the structural and functional properties of ion channels at the nerve terminals, using electrophysiology, dynamic Na(+) imaging and immunohistochemistry. The subcellular segregation of Na(+) channel expression and intracellular Na(+) dynamics at the heminode and terminal was lost in the dysmyelinated axon from Long-Evans shaker rats, which lack compact myelin. In Long-Evans shaker rats, loss of the Nav β4 subunit specifically at the heminode reduced resurgent and persistent Na(+) currents, whereas K(+) channel expression and currents were increased. The results of the present study suggest that there is a specific role for compact myelin in dictating protein expression and function at the axon heminode and in regulating excitability of the nerve terminal. ABSTRACT Axon myelination increases the conduction velocity and precision of action potential propagation. Although the negative effects of demyelination are generally attributed to conduction failure, accumulating evidence suggests that myelination also regulates the structural properties and molecular composition of the axonal membrane. In the present study, we investigated how myelination affects ion channel expression and function, particularly at the last axon heminode before the nerve terminal, which regulates the presynaptic excitability of the nerve terminal. We compared the structure and physiology of normal axons and those of the Long-Evans shaker (LES) rat, which lacks compact myelin. The normal segregation of Na(+) channel expression and dynamics at the heminode and terminal was lost in the LES rat. Specifically, NaV -α subunits were dispersed and NaV β4 subunit was absent, whereas the density of K(+) channels was increased at the heminode. Correspondingly, resurgent and persistent Na(+) currents were reduced and K(+) current was increased. Taken together, these data suggest a specific role for compact myelin in the orchestration of ion channel expression and function at the axon heminode and in regulating excitability of the nerve terminal.
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Affiliation(s)
| | | | | | | | - Jun Hee Kim
- Department of Physiology. .,Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, USA.
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