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Pál B. On the functions of astrocyte-mediated neuronal slow inward currents. Neural Regen Res 2024; 19:2602-2612. [PMID: 38595279 PMCID: PMC11168512 DOI: 10.4103/nrr.nrr-d-23-01723] [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: 10/17/2023] [Revised: 12/25/2023] [Accepted: 01/24/2024] [Indexed: 04/11/2024] Open
Abstract
Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extrasynaptic N-methyl-D-aspartate receptors with the contribution of astrocytes. These events are significantly slower than the excitatory postsynaptic currents. Parameters of slow inward currents are determined by several factors including the mechanisms of astrocytic activation and glutamate release, as well as the diffusion pathways from the release site towards the extrasynaptic receptors. Astrocytes are stimulated by neuronal network activity, which in turn excite neurons, forming an astrocyte-neuron feedback loop. Mostly as a consequence of brain edema, astrocytic swelling can also induce slow inward currents under pathological conditions. There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level. These events often occur in synchrony on neurons located in the same astrocytic domain. Besides synchronization of neuronal excitability, slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity. In addition, slow inward currents are also subject to non-synaptic plasticity triggered by long-lasting stimulation of the excitatory inputs. Of note, there might be important region-specific differences in the roles and actions triggering slow inward currents. In greater networks, the pathophysiological roles of slow inward currents can be better understood than physiological ones. Slow inward currents are identified in the pathophysiological background of autism, as slow inward currents drive early hypersynchrony of the neural networks. Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes. These events are related to epilepsy, but also found in Alzheimer's disease, Parkinson's disease, and stroke, leading to the decline of cognitive functions. Events with features overlapping with slow inward currents (excitatory, N-methyl-D-aspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke, traumatic brain injury, or epilepsy. One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation. However, to state this, more experimental evidence from greater neuronal networks or the level of the individual is needed. In this review, I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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2
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Frank R, Szarvas PA, Pesti I, Zsigmond A, Berkecz R, Menyhárt Á, Bari F, Farkas E. Nimodipine inhibits spreading depolarization, ischemic injury, and neuroinflammation in mouse live brain slice preparations. Eur J Pharmacol 2024; 977:176718. [PMID: 38849040 DOI: 10.1016/j.ejphar.2024.176718] [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: 04/11/2024] [Revised: 05/28/2024] [Accepted: 06/05/2024] [Indexed: 06/09/2024]
Abstract
Nimodipine is used to prevent delayed ischemic deficit in patients with aneurysmal subarachnoid hemorrhage (aSAH). Spreading depolarization (SD) is recognized as a factor in the pathomechanism of aSAH and other acute brain injuries. Although nimodipine is primarily known as a cerebral vasodilator, it may have a more complex mechanism of action due to the expression of its target, the L-type voltage-gated calcium channels (LVGCCs) in various cells in neural tissue. This study was designed to investigate the direct effect of nimodipine on SD, ischemic tissue injury, and neuroinflammation. SD in control or nimodipine-treated live mouse brain slices was induced under physiological conditions using electrical stimulation, or by subjecting the slices to hypo-osmotic stress or mild oxygen-glucose deprivation (mOGD). SD was recorded applying local field potential recording or intrinsic optical signal imaging. Histological analysis was used to estimate tissue injury, the number of reactive astrocytes, and the degree of microglia activation. Nimodipine did not prevent SD occurrence in mOGD, but it did reduce the rate of SD propagation and the cortical area affected by SD. In contrast, nimodipine blocked SD occurrence in hypo-osmotic stress, but had no effect on SD propagation. Furthermore, nimodipine prevented ischemic injury associated with SD in mOGD. Nimodipine also exhibited anti-inflammatory effects in mOGD by reducing reactive astrogliosis and microglial activation. The results demonstrate that nimodipine directly inhibits SD, independent of nimodipine's vascular effects. Therefore, the use of nimodipine may be extended to treat acute brain injuries where SD plays a central role in injury progression.
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Affiliation(s)
- Rita Frank
- Hungarian Centre of Excellence for Molecular Medicine - University of Szeged Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary; Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
| | - Péter Archibald Szarvas
- Hungarian Centre of Excellence for Molecular Medicine - University of Szeged Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary; Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - István Pesti
- Hungarian Centre of Excellence for Molecular Medicine - University of Szeged Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary; Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Anna Zsigmond
- Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Róbert Berkecz
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary; Department of Forensic Medicine, Albert Szent-Györgyi Health Centre, Kossuth Lajos Sgt. 40, Szeged, Hungary
| | - Ákos Menyhárt
- Hungarian Centre of Excellence for Molecular Medicine - University of Szeged Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary; Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Eszter Farkas
- Hungarian Centre of Excellence for Molecular Medicine - University of Szeged Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary; Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
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van Hameren G, Aboghazleh R, Parker E, Dreier JP, Kaufer D, Friedman A. From spreading depolarization to blood-brain barrier dysfunction: navigating traumatic brain injury for novel diagnosis and therapy. Nat Rev Neurol 2024; 20:408-425. [PMID: 38886512 DOI: 10.1038/s41582-024-00973-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2024] [Indexed: 06/20/2024]
Abstract
Considerable strides in medical interventions during the acute phase of traumatic brain injury (TBI) have brought improved overall survival rates. However, following TBI, people often face ongoing, persistent and debilitating long-term complications. Here, we review the recent literature to propose possible mechanisms that lead from TBI to long-term complications, focusing particularly on the involvement of a compromised blood-brain barrier (BBB). We discuss evidence for the role of spreading depolarization as a key pathological mechanism associated with microvascular dysfunction and the transformation of astrocytes to an inflammatory phenotype. Finally, we summarize new predictive and diagnostic biomarkers and explore potential therapeutic targets for treating long-term complications of TBI.
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Affiliation(s)
- Gerben van Hameren
- Department of Medical Neuroscience, Faculty of Medicine and Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Refat Aboghazleh
- Department of Medical Neuroscience, Faculty of Medicine and Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Basic Medical Sciences, Faculty of Medicine, Al-Balqa Applied University, Al-Salt, Jordan
| | - Ellen Parker
- Department of Medical Neuroscience, Faculty of Medicine and Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
- Division of Neurosurgery, Dalhousie University QEII Health Sciences Centre, Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
| | - Jens P Dreier
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany
- Einstein Center for Neurosciences Berlin, Berlin, Germany
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Daniela Kaufer
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Alon Friedman
- Department of Medical Neuroscience, Faculty of Medicine and Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada.
- Department of Cell Biology, Cognitive and Brain Sciences, Zelman Inter-Disciplinary Center of Brain Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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4
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Sen A, Erdivanlı B, Tümkaya L, Uydu HA, Mercantepe T, Batcik Ş, Ozdemir A. The effects of dexmedetomidine on trauma-induced secondary injury in rat brain. Neurol Res 2024; 46:23-32. [PMID: 37842946 DOI: 10.1080/01616412.2023.2257446] [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: 03/05/2023] [Accepted: 07/29/2023] [Indexed: 10/17/2023]
Abstract
BACKGROUND The objective of this study was to investigate the effect of dexmedetomidine (Dex), a sedative drug with little or no depressant effect on respiratory centers, on secondary injury in rat brain tissue by means of the Na+/K+ ATPase enzyme, which maintains the cell membrane ion gradient; malondialdehyde, an indicator of membrane lipid peroxidation; glutathione, an indicator of antioxidant capacity; and histopathological analyses. METHODS Eighteen rats were randomized into three groups: the trauma group received anesthesia, followed by head trauma with a Mild Traumatic Brain Injury Apparatus; the Trauma+Dex group received an additional treatment of 100 µg/kg intraperitoneal dexmedetomidine daily for three days; the Control group received anesthesia only. RESULTS The highest MDA levels compared to the Control group were found in the Trauma group. Mean levels in the Trauma+Dex group were lower, albeit still significantly high compared to the Control group. Glutathione levels were similar in all groups. Na/K-ATPase levels were significantly lower in the Trauma group compared to both the Control group and the Trauma+Dex group. Histopathologic findings of tissue degeneration including edema, vascular congestion and neuronal injury, and cleaved caspase-3 levels were lower in the Trauma+Dex group compared with the Trauma group. CONCLUSIONS Dexmedetomidine administered during the early stage of traumatic brain injury may inhibit caspase-3 cleavageHowever, the mechanism does not seem to be related to the improvement of MDA or GSH levels.
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Affiliation(s)
- Ahmet Sen
- Department of Anesthesiology and Reanimation, Trabzon Faculty of Medicine, University of Health Sciences, Trabzon, Turkey
| | - Basar Erdivanlı
- Department of Anestjesıology and Reamınatıon, Faculty of Medıcıne, Recep Tayyıp Erdogan Unıversıty
| | - Levent Tümkaya
- Histology and Embryology, Faculty of Medicine, Recep Tayyip Erdogan University, Rize, Turkey
| | - Hüseyin Avni Uydu
- Histology and Embryology and Biochemistry, Faculty of Medicine, Recep Tayyip Erdogan University, Rize, Turkey
| | - Tolga Mercantepe
- Histology and Embryology, Faculty of Medicine, Recep Tayyip Erdogan University, Rize, Turkey
| | - Şule Batcik
- Department of Anestjesıology and Reamınatıon, Faculty of Medıcıne, Recep Tayyıp Erdogan Unıversıty
| | - Abdullah Ozdemir
- Department of Anestjesıology and Reamınatıon, Faculty of Medıcıne, Recep Tayyıp Erdogan Unıversıty
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5
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Moore B, Sharma A, Goulet M, Suter T, Pelletier C, Hu R, Schaeffer E, Kelleher RJ. Developing a Gene Therapy for the Treatment of Autosomal Dominant Alzheimer's Disease. Hum Gene Ther 2023; 34:1049-1063. [PMID: 37578141 PMCID: PMC10623074 DOI: 10.1089/hum.2023.092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023] Open
Abstract
Autosomal dominant Alzheimer's disease (ADAD) is a rare early-onset form of Alzheimer's disease, caused by dominant mutations in one of three genes: presenilin 1, presenilin 2, and amyloid β precursor protein (APP). Mutations in the presenilin 1 gene (PSEN1) account for the majority of cases, and individuals who inherit a single-mutant PSEN1 allele go on to develop early-onset dementia, ultimately leading to death. The presenilin 1 protein (PS1) is the catalytic subunit of the γ-secretase protease, a tetrameric protease responsible for cleavage of numerous transmembrane proteins, including Notch and the APP. Inclusion of a mutant PS1 subunit in the γ-secretase complex leads to a loss of enzyme function and a preferential reduction of shorter forms of Aβ peptides over longer forms, an established biomarker of ADAD progression in human patients. In this study, we describe the development of a gene therapy vector expressing a wild-type (WT) copy of human PSEN1 to ameliorate the loss of function associated with PSEN1 mutations. We have carried out studies in mouse models using a recombinant AAV9 vector to deliver the PSEN1 gene directly into the central nervous system (CNS) and shown that we can normalize γ-secretase function and slow neurodegeneration in both PSEN1 conditional knockout and PSEN1 mutant knockin models. We have also carried out biodistribution studies in nonhuman primates (NHPs) and demonstrated the ability to achieve broad PS1 protein expression throughout the cortex and the hippocampus, two regions known to be critically involved in ADAD progression. These studies demonstrate preclinical proof of concept that expression of a WT human PSEN1 gene in cells harboring a dominant PSEN1 mutation can correct the γ-secretase dysfunction. In addition, direct administration of the recombinant AAV9 into the NHP brain can achieve broad expression at levels predicted to provide efficacy in the clinic.
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Affiliation(s)
| | | | | | | | | | - Ruoxi Hu
- Paros Bio, Boston, Massachusetts, USA
- Mass General Brigham Ventures (Partners Innovation Fund), Boston, Massachusetts, USA
| | | | - Raymond J. Kelleher
- Department of Neurology, and Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, USA
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Menyhárt Á, Frank R, Farkas AE, Süle Z, Varga VÉ, Nyúl-Tóth Á, Meiller A, Ivánkovits-Kiss O, Lemale CL, Szabó Í, Tóth R, Zölei-Szénási D, Woitzik J, Marinesco S, Krizbai IA, Bari F, Dreier JP, Farkas E. Malignant astrocyte swelling and impaired glutamate clearance drive the expansion of injurious spreading depolarization foci. J Cereb Blood Flow Metab 2022; 42:584-599. [PMID: 34427145 PMCID: PMC8943616 DOI: 10.1177/0271678x211040056] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Spreading depolarizations (SDs) indicate injury progression and predict worse clinical outcome in acute brain injury. We demonstrate in rodents that acute brain swelling upon cerebral ischemia impairs astroglial glutamate clearance and increases the tissue area invaded by SD. The cytotoxic extracellular glutamate accumulation (>15 µM) predisposes an extensive bulk of tissue (4-5 mm2) for a yet undescribed simultaneous depolarization (SiD). We confirm in rat brain slices exposed to osmotic stress that SiD is the pathological expansion of prior punctual SD foci (0.5-1 mm2), is associated with astrocyte swelling, and triggers oncotic neuron death. The blockade of astrocytic aquaporin-4 channels and Na+/K+/Cl- co-transporters, or volume-regulated anion channels mitigated slice edema, extracellular glutamate accumulation (<10 µM) and SiD occurrence. Reversal of slice swelling by hyperosmotic mannitol counteracted glutamate accumulation and prevented SiD. In contrast, inhibition of glial metabolism or inhibition of astrocyte glutamate transporters reproduced the SiD phenotype. Finally, we show in the rodent water intoxication model of cytotoxic edema that astrocyte swelling and altered astrocyte calcium waves are central in the evolution of SiD. We discuss our results in the light of evidence for SiD in the human cortex. Our results emphasize the need of preventive osmotherapy in acute brain injury.
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Affiliation(s)
- Ákos Menyhárt
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Rita Frank
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Attila E Farkas
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Zoltán Süle
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória É Varga
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Ádám Nyúl-Tóth
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Anne Meiller
- Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5292, University Claude Bernard Lyon I, Lyon, France
| | - Orsolya Ivánkovits-Kiss
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Coline L Lemale
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Írisz Szabó
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Réka Tóth
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Dániel Zölei-Szénási
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Johannes Woitzik
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Stephane Marinesco
- Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5292, University Claude Bernard Lyon I, Lyon, France
| | - István A Krizbai
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Institute of Life Sciences, Vasile Goldis Western University, Arad, Romania
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Jens P Dreier
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Eszter Farkas
- HCEMM-USZ Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary.,Department of Cell Biology and Molecular Medicine, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged,Szeged, Hungary
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7
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Lu YL, Scharfman HE. New Insights and Methods for Recording and Imaging Spontaneous Spreading Depolarizations and Seizure-Like Events in Mouse Hippocampal Slices. Front Cell Neurosci 2021; 15:761423. [PMID: 34899190 PMCID: PMC8663723 DOI: 10.3389/fncel.2021.761423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/04/2021] [Indexed: 11/30/2022] Open
Abstract
Spreading depolarization (SD) is a sudden, large, and synchronous depolarization of principal cells which also involves interneurons and astrocytes. It is followed by depression of neuronal activity, and it slowly propagates across brain regions like cortex or hippocampus. SD is considered to be mechanistically relevant to migraine, epilepsy, and traumatic brain injury (TBI), but there are many questions about its basic neurophysiology and spread. Research into SD in hippocampus using slices is often used to gain insight and SD is usually triggered by a focal stimulus with or without an altered extracellular buffer. Here, we optimize an in vitro experimental model allowing us to record SD without focal stimulation, which we call spontaneous. This method uses only an altered extracellular buffer containing 0 mM Mg2+ and 5 mM K+ and makes it possible for simultaneous patch and extracellular recording in a submerged chamber plus intrinsic optical imaging in slices of either sex. We also add methods for quantification and show the quantified optical signal is much more complex than imaging alone would suggest. In brief, acute hippocampal slices were prepared with a chamber holding a submerged slice but with flow of artificial cerebrospinal fluid (aCSF) above and below, which we call interface-like. As soon as slices were placed in the chamber, aCSF with 0 Mg2+/5 K+ was used. Most mouse slices developed SD and did so in the first hour of 0 Mg2+/5 K+ aCSF exposure. In addition, prolonged bursts we call seizure-like events (SLEs) occurred, and the interactions between SD and SLEs suggest potentially important relationships. Differences between rats and mice in different chambers are described. Regarding optical imaging, SD originated in CA3 and the pattern of spread to CA1 and the dentate gyrus was similar in some ways to prior studies but also showed interesting differences. In summary, the methods are easy to use, provide new opportunities to study SD, new insights, and are inexpensive. They support previous suggestions that SD is diverse, and also suggest that participation by the dentate gyrus merits greater attention.
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Affiliation(s)
- Yi-Ling Lu
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, United States
| | - Helen E. Scharfman
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, United States
- Department of Child and Adolescent Psychiatry, New York University Langone Health, New York, NY, United States
- Department of Neuroscience and Physiology, New York University Langone Health, New York, NY, United States
- Department of Psychiatry, New York University Langone Health, New York, NY, United States
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8
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Reinhart KM, Humphrey A, Brennan KC, Carlson AP, Shuttleworth CW. Memantine Improves Recovery After Spreading Depolarization in Brain Slices and can be Considered for Future Clinical Trials. Neurocrit Care 2021; 35:135-145. [PMID: 34657268 PMCID: PMC9938764 DOI: 10.1007/s12028-021-01351-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 09/02/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Spreading depolarization (SD) has been identified as a key mediator of secondary lesion progression after acute brain injuries, and clinical studies are beginning to pharmacologically target SDs. Although initial work has focused on the N-Methyl-D-aspartate receptor antagonist ketamine, there is also interest in alternatives that may be better tolerated. We recently showed that ketamine can inhibit mechanisms linked to deleterious consequences of SD in brain slices. The present study tested the hypothesis that memantine improves recovery of brain slices after SD and explored the effects of memantine in a clinical case targeting SD. METHODS For mechanistic studies, electrophysiological and optical recordings were made from hippocampal area CA1 in acutely prepared brain slices from mice. SDs were initiated by localized microinjection of K+ in conditions of either normal or reduced metabolic substrate availability. Memantine effects were assessed from intrinsic optical signals and extracellular potential recordings. For the clinical report, a subdural strip electrode was used for continuous electrocorticographic recording after the surgical evacuation of a chronic subdural hematoma. RESULTS In brain slice studies, memantine (10-300 µM) did not prevent the initiation of SD, but impaired SD propagation rate and recovery from SD. Memantine reduced direct current (DC) shift duration and improved recovery of synaptic potentials after SD. In brain slices with reduced metabolic substrate availability, memantine reduced the evidence of structural disruption after the passage of SD. In our clinical case, memantine did not noticeably immediately suppress SD; however, it was associated with a significant reduction of SD duration and a reduction in the electrocorticographic (ECoG) suppression that occurs after SD. SD was completely suppressed, with improvement in neurological examination with the addition of a brief course of ketamine. CONCLUSIONS These data extend recent work showing that N-Methyl-D-aspartate receptor antagonists can improve recovery from SD. These results suggest that memantine could be considered for future clinical trials targeting SD, and in some cases as an adjunct or alternative to ketamine.
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Affiliation(s)
- Katelyn M Reinhart
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Alanna Humphrey
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - K C Brennan
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Andrew P Carlson
- Department of Neurosurgery, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - C William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA.
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