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Sriram S, Carstens K, Dewing W, Fiacco TA. Astrocyte regulation of extracellular space parameters across the sleep-wake cycle. Front Cell Neurosci 2024; 18:1401698. [PMID: 38988660 PMCID: PMC11233815 DOI: 10.3389/fncel.2024.1401698] [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: 03/15/2024] [Accepted: 06/07/2024] [Indexed: 07/12/2024] Open
Abstract
Multiple subfields of neuroscience research are beginning to incorporate astrocytes into current frameworks of understanding overall brain physiology, neuronal circuitry, and disease etiology that underlie sleep and sleep-related disorders. Astrocytes have emerged as a dynamic regulator of neuronal activity through control of extracellular space (ECS) volume and composition, both of which can vary dramatically during different levels of sleep and arousal. Astrocytes are also an attractive target of sleep research due to their prominent role in the glymphatic system, a method by which toxic metabolites generated during wakefulness are cleared away. In this review we assess the literature surrounding glial influences on fluctuations in ECS volume and composition across the sleep-wake cycle. We also examine mechanisms of astrocyte volume regulation in glymphatic solute clearance and their role in sleep and wake states. Overall, findings highlight the importance of astrocytes in sleep and sleep research.
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Affiliation(s)
- Sandhya Sriram
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, CA, United States
- Department of Biochemistry and Molecular Biology, University of California, Riverside, Riverside, CA, United States
| | - Kaira Carstens
- Department of Biochemistry and Molecular Biology, University of California, Riverside, Riverside, CA, United States
| | - Wayne Dewing
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, CA, United States
| | - Todd A Fiacco
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, CA, United States
- Department of Biochemistry and Molecular Biology, University of California, Riverside, Riverside, CA, United States
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2
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Renden RB, Institoris A, Sharma K, Tran CHT. Modulatory effects of noradrenergic and serotonergic signaling pathway on neurovascular coupling. Commun Biol 2024; 7:287. [PMID: 38459113 PMCID: PMC10923894 DOI: 10.1038/s42003-024-05996-y] [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: 06/24/2023] [Accepted: 02/28/2024] [Indexed: 03/10/2024] Open
Abstract
Dynamic changes in astrocyte Ca2+ are recognized as contributors to functional hyperemia, a critical response to increased neuronal activity mediated by a process known as neurovascular coupling (NVC). Although the critical role of glutamatergic signaling in this process has been extensively investigated, the impact of behavioral state, and the release of behavior-associated neurotransmitters, such as norepinephrine and serotonin, on astrocyte Ca2+ dynamics and functional hyperemia have received less attention. We used two-photon imaging of the barrel cortex in awake mice to examine the role of noradrenergic and serotonergic projections in NVC. We found that both neurotransmitters facilitated sensory stimulation-induced increases in astrocyte Ca2+. Interestingly, while ablation of serotonergic neurons reduced sensory stimulation-induced functional hyperemia, ablation of noradrenergic neurons caused both attenuation and potentiation of functional hyperemia. Our study demonstrates that norepinephrine and serotonin are involved in modulating sensory stimulation-induced astrocyte Ca2+ elevations and identifies their differential effects in regulating functional hyperemia.
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Affiliation(s)
- Robert B Renden
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA
| | - Adam Institoris
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Kushal Sharma
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA
| | - Cam Ha T Tran
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV, USA.
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3
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Montalant A, Kiehn O, Perrier JF. Dopamine and noradrenaline activate spinal astrocyte endfeet via D1-like receptors. Eur J Neurosci 2024; 59:1278-1295. [PMID: 38052454 DOI: 10.1111/ejn.16205] [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: 09/08/2023] [Revised: 11/02/2023] [Accepted: 11/10/2023] [Indexed: 12/07/2023]
Abstract
Astrocytes, the most abundant glial cells in the central nervous system, respond to a wide variety of neurotransmitters binding to metabotropic receptors. Here, we investigated the intracellular calcium responses of spinal cord astrocytes to dopamine and noradrenaline, two catecholamines released by specific descending pathways. In a slice preparation from the spinal cord of neonatal mice, puff application of dopamine resulted in intracellular calcium responses that remained in the endfeet. Noradrenaline induced stronger responses that also started in the endfeet but spread to neighbouring compartments. The intracellular calcium responses were unaffected by blocking neuronal activity or inhibiting various neurotransmitter receptors, suggesting a direct effect of dopamine and noradrenaline on astrocytes. The intracellular calcium responses induced by noradrenaline and dopamine were inhibited by the D1 receptor antagonist SCH 23390. We assessed the functional consequences of these astrocytic responses by examining changes in arteriole diameter. Puff application of dopamine or noradrenaline resulted in vasoconstriction of spinal arterioles. However, blocking D1 receptors or manipulating astrocytic intracellular calcium levels did not abolish the vasoconstrictions, indicating that the observed intracellular calcium responses in astrocyte endfeet were not responsible for the vascular changes. Our findings demonstrate a compartmentalized response of spinal cord astrocytes to catecholamines and expand our understanding of astrocyte-neurotransmitter interactions and their potential roles in the physiology of the central nervous system.
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Affiliation(s)
- Alexia Montalant
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ole Kiehn
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jean-François Perrier
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Raut RV, Rosenthal ZP, Wang X, Miao H, Zhang Z, Lee JM, Raichle ME, Bauer AQ, Brunton SL, Brunton BW, Kutz JN. Arousal as a universal embedding for spatiotemporal brain dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.06.565918. [PMID: 38187528 PMCID: PMC10769245 DOI: 10.1101/2023.11.06.565918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Neural activity in awake organisms shows widespread and spatiotemporally diverse correlations with behavioral and physiological measurements. We propose that this covariation reflects in part the dynamics of a unified, arousal-related process that regulates brain-wide physiology on the timescale of seconds. Taken together with theoretical foundations in dynamical systems, this interpretation leads us to a surprising prediction: that a single, scalar measurement of arousal (e.g., pupil diameter) should suffice to reconstruct the continuous evolution of multimodal, spatiotemporal measurements of large-scale brain physiology. To test this hypothesis, we perform multimodal, cortex-wide optical imaging and behavioral monitoring in awake mice. We demonstrate that spatiotemporal measurements of neuronal calcium, metabolism, and blood-oxygen can be accurately and parsimoniously modeled from a low-dimensional state-space reconstructed from the time history of pupil diameter. Extending this framework to behavioral and electrophysiological measurements from the Allen Brain Observatory, we demonstrate the ability to integrate diverse experimental data into a unified generative model via mappings from an intrinsic arousal manifold. Our results support the hypothesis that spontaneous, spatially structured fluctuations in brain-wide physiology-widely interpreted to reflect regionally-specific neural communication-are in large part reflections of an arousal-related process. This enriched view of arousal dynamics has broad implications for interpreting observations of brain, body, and behavior as measured across modalities, contexts, and scales.
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Affiliation(s)
- Ryan V. Raut
- Allen Institute, Seattle, WA, USA
- Department of Physiology & Biophysics, University of Washington, Seattle, WA, USA
| | - Zachary P. Rosenthal
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xiaodan Wang
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Hanyang Miao
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Zhanqi Zhang
- Department of Computer Science & Engineering, University of California San Diego, La Jolla, CA, USA
| | - Jin-Moo Lee
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Marcus E. Raichle
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Adam Q. Bauer
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Steven L. Brunton
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | | | - J. Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, WA, USA
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Postnov D, Semyachkina-Glushkovskaya O, Litvinenko E, Kurths J, Penzel T. Mechanisms of Activation of Brain's Drainage during Sleep: The Nightlife of Astrocytes. Cells 2023; 12:2667. [PMID: 37998402 PMCID: PMC10670149 DOI: 10.3390/cells12222667] [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: 10/15/2023] [Revised: 11/09/2023] [Accepted: 11/15/2023] [Indexed: 11/25/2023] Open
Abstract
The study of functions, mechanisms of generation, and pathways of movement of cerebral fluids has a long history, but the last decade has been especially productive. The proposed glymphatic hypothesis, which suggests a mechanism of the brain waste removal system (BWRS), caused an active discussion on both the criticism of some of the perspectives and our intensive study of new experimental facts. It was especially found that the intensity of the metabolite clearance changes significantly during the transition between sleep and wakefulness. Interestingly, at the cellular level, a number of aspects of this problem have been focused on, such as astrocytes-glial cells, which, over the past two decades, have been recognized as equal partners of neurons and perform many important functions. In particular, an important role was assigned to astrocytes within the framework of the glymphatic hypothesis. In this review, we return to the "astrocytocentric" view of the BWRS function and the explanation of its activation during sleep from the viewpoint of new findings over the last decade. Our main conclusion is that the BWRS's action may be analyzed both at the systemic (whole-brain) and at the local (cellular) level. The local level means here that the neuro-glial-vascular unit can also be regarded as the smallest functional unit of sleep, and therefore, the smallest functional unit of the BWRS.
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Affiliation(s)
- Dmitry Postnov
- Department of Optics and Biophotonics, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov, Russia;
| | - Oxana Semyachkina-Glushkovskaya
- Department of Biology, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov, Russia; (O.S.-G.); (J.K.)
- Physics Department, Humboldt University, Newtonstrasse 15, 12489 Berlin, Germany
| | - Elena Litvinenko
- Department of Optics and Biophotonics, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov, Russia;
| | - Jürgen Kurths
- Department of Biology, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov, Russia; (O.S.-G.); (J.K.)
- Physics Department, Humboldt University, Newtonstrasse 15, 12489 Berlin, Germany
- Potsdam Institute for Climate Impact Research, Telegrafenberg A31, 14473 Potsdam, Germany
| | - Thomas Penzel
- Department of Biology, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov, Russia; (O.S.-G.); (J.K.)
- Charité — Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
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Freeze WM, van Veluw SJ, Jansen WJ, Bennett DA, Jacobs HIL. Locus coeruleus pathology is associated with cerebral microangiopathy at autopsy. Alzheimers Dement 2023; 19:5023-5035. [PMID: 37095709 PMCID: PMC10593911 DOI: 10.1002/alz.13096] [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: 10/14/2022] [Revised: 03/10/2023] [Accepted: 03/27/2023] [Indexed: 04/26/2023]
Abstract
INTRODUCTION We investigated the link between locus coeruleus (LC) pathology and cerebral microangiopathy in two large neuropathology datasets. METHODS We included data from the National Alzheimer's Coordinating Center (NACC) database (n = 2197) and Religious Orders Study and Rush Memory and Aging Project (ROSMAP; n = 1637). Generalized estimating equations and logistic regression were used to examine associations between LC hypopigmentation and presence of cerebral amyloid angiopathy (CAA) or arteriolosclerosis, correcting for age at death, sex, cortical Alzheimer's disease (AD) pathology, ante mortem cognitive status, and presence of vascular and genetic risk factors. RESULTS LC hypopigmentation was associated with higher odds of overall CAA in the NACC dataset, leptomeningeal CAA in the ROSMAP dataset, and arteriolosclerosis in both datasets. DISCUSSION LC pathology is associated with cerebral microangiopathy, independent of cortical AD pathology. LC degeneration could potentially contribute to the pathways relating vascular pathology to AD. Future studies of the LC-norepinephrine system on cerebrovascular health are warranted. HIGHLIGHTS We associated locus coeruleus (LC) pathology and cerebral microangiopathy in two large autopsy datasets. LC hypopigmentation was consistently related to arteriolosclerosis in both datasets. LC hypopigmentation was related to cerebral amyloid angiopathy (CAA) presence in the National Alzheimer's Coordinating Center dataset. LC hypopigmentation was related to leptomeningeal CAA in the Religious Orders Study and Rush Memory and Aging Project dataset. LC degeneration may play a role in the pathways relating vascular pathology to Alzheimer's disease.
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Affiliation(s)
- WM Freeze
- Department of Radiology, Leiden University Medical Center, 2333 ZA, Leiden, the Netherlands
- Department of Psychiatry and Neuropsychology, Alzheimer Center Limburg, School for Mental Health and Neuroscience, Maastricht University, 6229 ET, Maastricht, the Netherlands
| | - SJ van Veluw
- Department of Radiology, Leiden University Medical Center, 2333 ZA, Leiden, the Netherlands
- Department of Neurology, J. Philip Kistler Stroke Research Center, MGH, Boston, MA 02114, USA
| | - WJ Jansen
- Department of Psychiatry and Neuropsychology, Alzheimer Center Limburg, School for Mental Health and Neuroscience, Maastricht University, 6229 ET, Maastricht, the Netherlands
- Banner Alzheimer’s Institute, Phoenix, AZ 85006, USA
| | - DA Bennett
- Department of Neurological Sciences, Rush Alzheimer’s Disease Center, Rush University Medical Center; Chicago, IL 60612, USA
| | - HIL Jacobs
- Department of Psychiatry and Neuropsychology, Alzheimer Center Limburg, School for Mental Health and Neuroscience, Maastricht University, 6229 ET, Maastricht, the Netherlands
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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Brazhe A, Verisokin A, Verveyko D, Postnov D. Astrocytes: new evidence, new models, new roles. Biophys Rev 2023; 15:1303-1333. [PMID: 37975000 PMCID: PMC10643736 DOI: 10.1007/s12551-023-01145-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/08/2023] [Indexed: 11/19/2023] Open
Abstract
Astrocytes have been in the limelight of active research for about 3 decades now. Over this period, ideas about their function and role in the nervous system have evolved from simple assistance in energy supply and homeostasis maintenance to a complex informational and metabolic hub that integrates data on local neuronal activity, sensory and arousal context, and orchestrates many crucial processes in the brain. Rapid progress in experimental techniques and data analysis produces a growing body of data, which can be used as a foundation for formulation of new hypotheses, building new refined mathematical models, and ultimately should lead to a new level of understanding of the contribution of astrocytes to the cognitive tasks performed by the brain. Here, we highlight recent progress in astrocyte research, which we believe expands our understanding of how low-level signaling at a cellular level builds up to processes at the level of the whole brain and animal behavior. We start our review with revisiting data on the role of noradrenaline-mediated astrocytic signaling in locomotion, arousal, sensory integration, memory, and sleep. We then briefly review astrocyte contribution to the regulation of cerebral blood flow regulation, which is followed by a discussion of biophysical mechanisms underlying astrocyte effects on different brain processes. The experimental section is closed by an overview of recent experimental techniques available for modulation and visualization of astrocyte dynamics. We then evaluate how the new data can be potentially incorporated into the new mathematical models or where and how it already has been done. Finally, we discuss an interesting prospect that astrocytes may be key players in important processes such as the switching between sleep and wakefulness and the removal of toxic metabolites from the brain milieu.
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Affiliation(s)
- Alexey Brazhe
- Department of Biophysics, Biological Faculty, Lomonosov Moscow State University, Leninskie Gory, 1/24, Moscow, 119234 Russia
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry RAS, GSP-7, Miklukho-Maklay Str., 16/10, Moscow, 117997 Russia
| | - Andrey Verisokin
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Darya Verveyko
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Dmitry Postnov
- Department of Optics and Biophotonics, Saratov State University, Astrakhanskaya st., 83, Saratov, 410012 Russia
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McDonald B, Barth K, Schmidt MHH. The origin of brain malignancies at the blood-brain barrier. Cell Mol Life Sci 2023; 80:282. [PMID: 37688612 PMCID: PMC10492883 DOI: 10.1007/s00018-023-04934-1] [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: 05/17/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/11/2023]
Abstract
Despite improvements in extracranial therapy, survival rate for patients suffering from brain metastases remains very poor. This is coupled with the incidence of brain metastases continuing to rise. In this review, we focus on core contributions of the blood-brain barrier to the origin of brain metastases. We first provide an overview of the structure and function of the blood-brain barrier under physiological conditions. Next, we discuss the emerging idea of a pre-metastatic niche, namely that secreted factors and extracellular vesicles from a primary tumor site are able to travel through the circulation and prime the neurovasculature for metastatic invasion. We then consider the neurotropic mechanisms that circulating tumor cells possess or develop that facilitate disruption of the blood-brain barrier and survival in the brain's parenchyma. Finally, we compare and contrast brain metastases at the blood-brain barrier to the primary brain tumor, glioma, examining the process of vessel co-option that favors the survival and outgrowth of brain malignancies.
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Affiliation(s)
- Brennan McDonald
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany.
| | - Kathrin Barth
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany
| | - Mirko H H Schmidt
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany
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Matt RA, Martin RS, Evans AK, Gever JR, Vargas GA, Shamloo M, Ford AP. Locus Coeruleus and Noradrenergic Pharmacology in Neurodegenerative Disease. Handb Exp Pharmacol 2023. [PMID: 37495851 DOI: 10.1007/164_2023_677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Adrenoceptors (ARs) throughout the brain are stimulated by noradrenaline originating mostly from neurons of the locus coeruleus, a brainstem nucleus that is ostensibly the earliest to show detectable pathology in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The α1-AR, α2-AR, and β-AR subtypes expressed in target brain regions and on a range of cell populations define the physiological responses to noradrenaline, which includes activation of cognitive function in addition to modulation of neurometabolism, cerebral blood flow, and neuroinflammation. As these heterocellular functions are critical for maintaining brain homeostasis and neuronal health, combating the loss of noradrenergic tone from locus coeruleus degeneration may therefore be an effective treatment for both cognitive symptoms and disease modification in neurodegenerative indications. Two pharmacologic approaches are receiving attention in recent clinical studies: preserving noradrenaline levels (e.g., via reuptake inhibition) and direct activation of target adrenoceptors. Here, we review the expression and role of adrenoceptors in the brain, the preclinical studies which demonstrate that adrenergic stimulation can support cognitive function and cerebral health by reversing the effects of noradrenaline depletion, and the human data provided by pharmacoepidemiologic analyses and clinical trials which together identify adrenoceptors as promising targets for the treatment of neurodegenerative disease.
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Affiliation(s)
| | | | - Andrew K Evans
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, CA, USA
| | | | | | - Mehrdad Shamloo
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, CA, USA
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Novorolsky RJ, Kasheke GDS, Hakim A, Foldvari M, Dorighello GG, Sekler I, Vuligonda V, Sanders ME, Renden RB, Wilson JJ, Robertson GS. Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery. Front Cell Neurosci 2023; 17:1226630. [PMID: 37484823 PMCID: PMC10360135 DOI: 10.3389/fncel.2023.1226630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.
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Affiliation(s)
- Robyn J. Novorolsky
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Gracious D. S. Kasheke
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Antoine Hakim
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Marianna Foldvari
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel G. Dorighello
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben Gurion University, Beersheva, Israel
| | | | | | - Robert B. Renden
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, College of Arts and Sciences, Cornell University, Ithaca, NY, United States
| | - George S. Robertson
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Psychiatry, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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11
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Korte N, James G, You H, Hirunpattarasilp C, Christie I, Sethi H, Attwell D. Noradrenaline released from locus coeruleus axons contracts cerebral capillary pericytes via α2 adrenergic receptors. J Cereb Blood Flow Metab 2023; 43:1142-1152. [PMID: 36688515 PMCID: PMC10291462 DOI: 10.1177/0271678x231152549] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/15/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023]
Abstract
Noradrenaline (NA) release from locus coeruleus axons generates vascular contractile tone in arteriolar smooth muscle and contractile capillary pericytes. This tone allows neuronal activity to evoke vasodilation that increases local cerebral blood flow (CBF). Much of the vascular resistance within the brain is located in capillaries and locus coeruleus axons have NA release sites closer to pericytes than to arterioles. In acute brain slices, NA contracted pericytes but did not raise the pericyte cytoplasmic Ca2+ concentration, while the α1 agonist phenylephrine did not evoke contraction. Blocking α2 adrenergic receptors (α2Rs, which induce contraction by inhibiting cAMP production), greatly reduced the NA-evoked pericyte contraction, whereas stimulating α2Rs using xylazine (a sedative) or clonidine (an anti-hypertensive drug) evoked pericyte contraction. Noradrenaline-evoked pericyte contraction and capillary constriction are thus mediated via α2Rs. Consequently, α2Rs may not only modulate CBF in health and pathological conditions, but also contribute to CBF changes evoked by α2R ligands administered in research, veterinary and clinical settings.
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Affiliation(s)
- Nils Korte
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Greg James
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
| | - Haoming You
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Chanawee Hirunpattarasilp
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Isabel Christie
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Huma Sethi
- Dept of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, UK
| | - David Attwell
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
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12
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Ehrenberg AJ, Kelberman MA, Liu KY, Dahl MJ, Weinshenker D, Falgàs N, Dutt S, Mather M, Ludwig M, Betts MJ, Winer JR, Teipel S, Weigand AJ, Eschenko O, Hämmerer D, Leiman M, Counts SE, Shine JM, Robertson IH, Levey AI, Lancini E, Son G, Schneider C, Egroo MV, Liguori C, Wang Q, Vazey EM, Rodriguez-Porcel F, Haag L, Bondi MW, Vanneste S, Freeze WM, Yi YJ, Maldinov M, Gatchel J, Satpati A, Babiloni C, Kremen WS, Howard R, Jacobs HIL, Grinberg LT. Priorities for research on neuromodulatory subcortical systems in Alzheimer's disease: Position paper from the NSS PIA of ISTAART. Alzheimers Dement 2023; 19:2182-2196. [PMID: 36642985 PMCID: PMC10182252 DOI: 10.1002/alz.12937] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/08/2022] [Accepted: 12/19/2022] [Indexed: 01/17/2023]
Abstract
The neuromodulatory subcortical system (NSS) nuclei are critical hubs for survival, hedonic tone, and homeostasis. Tau-associated NSS degeneration occurs early in Alzheimer's disease (AD) pathogenesis, long before the emergence of pathognomonic memory dysfunction and cortical lesions. Accumulating evidence supports the role of NSS dysfunction and degeneration in the behavioral and neuropsychiatric manifestations featured early in AD. Experimental studies even suggest that AD-associated NSS degeneration drives brain neuroinflammatory status and contributes to disease progression, including the exacerbation of cortical lesions. Given the important pathophysiologic and etiologic roles that involve the NSS in early AD stages, there is an urgent need to expand our understanding of the mechanisms underlying NSS vulnerability and more precisely detail the clinical progression of NSS changes in AD. Here, the NSS Professional Interest Area of the International Society to Advance Alzheimer's Research and Treatment highlights knowledge gaps about NSS within AD and provides recommendations for priorities specific to clinical research, biomarker development, modeling, and intervention. HIGHLIGHTS: Neuromodulatory nuclei degenerate in early Alzheimer's disease pathological stages. Alzheimer's pathophysiology is exacerbated by neuromodulatory nuclei degeneration. Neuromodulatory nuclei degeneration drives neuropsychiatric symptoms in dementia. Biomarkers of neuromodulatory integrity would be value-creating for dementia care. Neuromodulatory nuclei present strategic prospects for disease-modifying therapies.
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Affiliation(s)
- Alexander J Ehrenberg
- Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, California, USA
| | - Michael A Kelberman
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Kathy Y Liu
- Division of Psychiatry, University College London, London, UK
| | - Martin J Dahl
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - David Weinshenker
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Neus Falgàs
- Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Service, Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain
- Global Brain Health Institute, University of California, San Francisco, San Francisco, California, USA
| | - Shubir Dutt
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
- Department of Psychology, University of Southern California, Los Angeles, California, USA
| | - Mara Mather
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
- Department of Psychology, University of Southern California, Los Angeles, California, USA
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
| | - Mareike Ludwig
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences, University of Magdeburg, Magdeburg, Germany
| | - Matthew J Betts
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences, University of Magdeburg, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Joseph R Winer
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Stefan Teipel
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Rostock/Greifswald, Rostock, Germany
- Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany
| | - Alexandra J Weigand
- San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, California, USA
| | - Oxana Eschenko
- Department of Computational Neuroscience, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Dorothea Hämmerer
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
- Department of Psychology, University of Innsbruck, Innsbruck, Austria
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Marina Leiman
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Scott E Counts
- Department of Translational Neuroscience, Michigan State University, Grand Rapids, Michigan, USA
- Department of Family Medicine, Michigan State University, Grand Rapids, Michigan, USA
- Michigan Alzheimer's Disease Research Center, Ann Arbor, Michigan, USA
| | - James M Shine
- Brain and Mind Center, The University of Sydney, Sydney, Australia
| | - Ian H Robertson
- Global Brain Health Institute, Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Allan I Levey
- Goizueta Alzheimer's Disease Research Center, Emory University, Atlanta, Georgia, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, USA
- Goizueta Institute, Emory University, Atlanta, Georgia, USA
| | - Elisa Lancini
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Gowoon Son
- Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
| | - Christoph Schneider
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Maxime Van Egroo
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Faculty of Health, Medicine, and Life Sciences, School for Mental Health and Neuroscience, Alzheimer Centre Limburg, Maastricht University, Maastricht, the Netherlands
| | - Claudio Liguori
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
- Neurology Unit, University Hospital of Rome Tor Vergata, Rome, Italy
| | - Qin Wang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Agusta University, Agusta, Georgia, USA
| | - Elena M Vazey
- Department of Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | | | - Lena Haag
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Mark W Bondi
- Department of Psychiatry, University of California, San Diego, La Jolla, California, USA
- Psychology Service, VA San Diego Healthcare System, San Diego, California, USA
| | - Sven Vanneste
- Global Brain Health Institute, Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
- School of Psychology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Whitney M Freeze
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Neuropsychology and Psychiatry, Maastricht University, Maastricht, the Netherlands
| | - Yeo-Jin Yi
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Mihovil Maldinov
- Department of Psychiatry and Psychotherapy, University of Rostock, Rostock, Germany
| | - Jennifer Gatchel
- Division of Geriatric Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Abhijit Satpati
- Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
| | - Claudio Babiloni
- Department of Physiology and Pharmacology "V. Erspamer,", Sapienza University of Rome, Rome, Italy
- Hospital San Raffaele Cassino, Cassino, Italy
| | - William S Kremen
- Center for Behavior Genetics of Aging, University of California, San Diego, La Jolla, California, USA
| | - Robert Howard
- Division of Psychiatry, University College London, London, UK
| | - Heidi I L Jacobs
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Faculty of Health, Medicine, and Life Sciences, School for Mental Health and Neuroscience, Alzheimer Centre Limburg, Maastricht University, Maastricht, the Netherlands
| | - Lea T Grinberg
- Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA
- Global Brain Health Institute, University of California, San Francisco, San Francisco, California, USA
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
- Department of Pathology, University of São Paulo Medical School, São Paulo, Brazil
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13
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Natsubori A, Hirai S, Kwon S, Ono D, Deng F, Wan J, Miyazawa M, Kojima T, Okado H, Karashima A, Li Y, Tanaka KF, Honda M. Serotonergic neurons control cortical neuronal intracellular energy dynamics by modulating astrocyte-neuron lactate shuttle. iScience 2023; 26:105830. [PMID: 36713262 PMCID: PMC9881222 DOI: 10.1016/j.isci.2022.105830] [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: 02/13/2022] [Revised: 08/15/2022] [Accepted: 12/12/2022] [Indexed: 01/07/2023] Open
Abstract
The central serotonergic system has multiple roles in animal physiology and behavior, including sleep-wake control. However, its function in controlling brain energy metabolism according to the state of animals remains undetermined. Through in vivo monitoring of energy metabolites and signaling, we demonstrated that optogenetic activation of raphe serotonergic neurons increased cortical neuronal intracellular concentration of ATP, an indispensable cellular energy molecule, which was suppressed by inhibiting neuronal uptake of lactate derived from astrocytes. Raphe serotonergic neuronal activation induced cortical astrocytic Ca2+ and cAMP surges and increased extracellular lactate concentrations, suggesting the facilitation of lactate release from astrocytes. Furthermore, chemogenetic inhibition of raphe serotonergic neurons partly attenuated the increase in cortical neuronal intracellular ATP levels as arousal increased in mice. Serotonergic neuronal activation promoted an increase in cortical neuronal intracellular ATP levels, partly mediated by the facilitation of the astrocyte-neuron lactate shuttle, contributing to state-dependent optimization of neuronal intracellular energy levels.
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Affiliation(s)
- Akiyo Natsubori
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan,Corresponding author
| | - Shinobu Hirai
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
| | - Soojin Kwon
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
| | - Daisuke Ono
- Department of Neuroscience Ⅱ, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan,Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Fei Deng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Jinxia Wan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Momoka Miyazawa
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan,Faculty of Science Division Ⅱ, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Takashi Kojima
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
| | - Haruo Okado
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
| | - Akihiro Karashima
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, Sendai 982-8577, Japan
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Kenji F. Tanaka
- Division of Brain Sciences, Institute for Advanced Medical Research, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Makoto Honda
- Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan
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14
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Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage. Cells 2022; 11:cells11182823. [PMID: 36139398 PMCID: PMC9496956 DOI: 10.3390/cells11182823] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/18/2022] [Accepted: 08/30/2022] [Indexed: 11/23/2022] Open
Abstract
Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.
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15
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Osorio-Forero A, Cherrad N, Banterle L, Fernandez LMJ, Lüthi A. When the Locus Coeruleus Speaks Up in Sleep: Recent Insights, Emerging Perspectives. Int J Mol Sci 2022; 23:ijms23095028. [PMID: 35563419 PMCID: PMC9099715 DOI: 10.3390/ijms23095028] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 12/03/2022] Open
Abstract
For decades, numerous seminal studies have built our understanding of the locus coeruleus (LC), the vertebrate brain’s principal noradrenergic system. Containing a numerically small but broadly efferent cell population, the LC provides brain-wide noradrenergic modulation that optimizes network function in the context of attentive and flexible interaction with the sensory environment. This review turns attention to the LC’s roles during sleep. We show that these roles go beyond down-scaled versions of the ones in wakefulness. Novel dynamic assessments of noradrenaline signaling and LC activity uncover a rich diversity of activity patterns that establish the LC as an integral portion of sleep regulation and function. The LC could be involved in beneficial functions for the sleeping brain, and even minute alterations in its functionality may prove quintessential in sleep disorders.
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16
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Hartmann DA, Coelho-Santos V, Shih AY. Pericyte Control of Blood Flow Across Microvascular Zones in the Central Nervous System. Annu Rev Physiol 2022; 84:331-354. [PMID: 34672718 PMCID: PMC10480047 DOI: 10.1146/annurev-physiol-061121-040127] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The vast majority of the brain's vascular length is composed of capillaries, where our understanding of blood flow control remains incomplete. This review synthesizes current knowledge on the control of blood flow across microvascular zones by addressing issues with nomenclature and drawing on new developments from in vivo optical imaging and single-cell transcriptomics. Recent studies have highlighted important distinctions in mural cell morphology, gene expression, and contractile dynamics, which can explain observed differences in response to vasoactive mediators between arteriole, transitional, and capillary zones. Smooth muscle cells of arterioles and ensheathing pericytes of the arteriole-capillary transitional zone control large-scale, rapid changes in blood flow. In contrast, capillary pericytes downstream of the transitional zone act on slower and smaller scales and are involved in establishing resting capillary tone and flow heterogeneity. Many unresolved issues remain, including the vasoactive mediators that activate the different pericyte types in vivo, the role of pericyte-endothelial communication in conducting signals from capillaries to arterioles, and how neurological disease affects these mechanisms.
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Affiliation(s)
- David A Hartmann
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California, USA
| | - Vanessa Coelho-Santos
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA;
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Andy Y Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA;
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
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17
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Hussain B, Fang C, Chang J. Blood-Brain Barrier Breakdown: An Emerging Biomarker of Cognitive Impairment in Normal Aging and Dementia. Front Neurosci 2021; 15:688090. [PMID: 34489623 PMCID: PMC8418300 DOI: 10.3389/fnins.2021.688090] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/14/2021] [Indexed: 12/11/2022] Open
Abstract
The blood–brain barrier (BBB) plays a vital role in maintaining the specialized microenvironment of the neural tissue. It separates the peripheral circulatory system from the brain parenchyma while facilitating communication. Alterations in the distinct physiological properties of the BBB lead to BBB breakdown associated with normal aging and various neurodegenerative diseases. In this review, we first briefly discuss the aging process, then review the phenotypes and mechanisms of BBB breakdown associated with normal aging that further cause neurodegeneration and cognitive impairments. We also summarize dementia such as Alzheimer's disease (AD) and vascular dementia (VaD) and subsequently discuss the phenotypes and mechanisms of BBB disruption in dementia correlated with cognition decline. Overlaps between AD and VaD are also discussed. Techniques that could identify biomarkers associated with BBB breakdown are briefly summarized. Finally, we concluded that BBB breakdown could be used as an emerging biomarker to assist to diagnose cognitive impairment associated with normal aging and dementia.
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Affiliation(s)
- Basharat Hussain
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Cheng Fang
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Junlei Chang
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
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18
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Sommonte F, Arduino I, Racaniello GF, Lopalco A, Lopedota AA, Denora N. The Complexity of the Blood-Brain Barrier and the Concept of Age-Related Brain Targeting: Challenges and Potential of Novel Solid Lipid-Based Formulations. J Pharm Sci 2021; 111:577-592. [PMID: 34469749 DOI: 10.1016/j.xphs.2021.08.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022]
Abstract
Diseases that affect the Central Nervous System (CNS) are one of the most exciting challenges of recent years, as they are ubiquitous and affect all ages. Although these disorders show different etiologies, all treatments share the same difficulty represented by the Blood-Brain Barrier (BBB). This barrier acts as a protective system of the delicate cerebral microenvironment, isolating it and making extremely arduous delivering drugs to the brain. To overtake the obstacles provided by the BBB it is essential to explore the changes that affect it, to understand how to exploit these findings in the study and design of innovative brain targeted formulations. Interestingly, the concept of age-related targeting could prove to be a winning choice, as it allows to consider the type of treatment according to the different needs and peculiarities depending on the disease and the age of onset. In this review was considered the prospective contribution of lipid-based formulations, namely Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs), which have been highlighted as able to overcome some limitations of other innovative approaches, thus representing a promising strategy for the non-invasive specific treatment of CNS-related diseases.
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Affiliation(s)
- Federica Sommonte
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., 70125, Bari, Italy
| | - Ilaria Arduino
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., 70125, Bari, Italy
| | | | - Antonio Lopalco
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., 70125, Bari, Italy
| | - Angela Assunta Lopedota
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., 70125, Bari, Italy
| | - Nunzio Denora
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari "Aldo Moro", 4 Orabona St., 70125, Bari, Italy.
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19
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Eltanahy AM, Koluib YA, Gonzales A. Pericytes: Intrinsic Transportation Engineers of the CNS Microcirculation. Front Physiol 2021; 12:719701. [PMID: 34497540 PMCID: PMC8421025 DOI: 10.3389/fphys.2021.719701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 07/29/2021] [Indexed: 12/15/2022] Open
Abstract
Pericytes in the brain are candidate regulators of microcirculatory blood flow because they are strategically positioned along the microvasculature, contain contractile proteins, respond rapidly to neuronal activation, and synchronize microvascular dynamics and neurovascular coupling within the capillary network. Analyses of mice with defects in pericyte generation demonstrate that pericytes are necessary for the formation of the blood-brain barrier, development of the glymphatic system, immune homeostasis, and white matter function. The development, identity, specialization, and progeny of different subtypes of pericytes, however, remain unclear. Pericytes perform brain-wide 'transportation engineering' functions in the capillary network, instructing, integrating, and coordinating signals within the cellular communicome in the neurovascular unit to efficiently distribute oxygen and nutrients ('goods and services') throughout the microvasculature ('transportation grid'). In this review, we identify emerging challenges in pericyte biology and shed light on potential pericyte-targeted therapeutic strategies.
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Affiliation(s)
- Ahmed M. Eltanahy
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Yara A. Koluib
- Tanta University Hospitals, Faculty of Medicine, Tanta University, Tanta, Egypt
| | - Albert Gonzales
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
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20
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Luckey AM, Robertson IH, Lawlor B, Mohan A, Vanneste S. Sex Differences in Locus Coeruleus: A Heuristic Approach That May Explain the Increased Risk of Alzheimer's Disease in Females. J Alzheimers Dis 2021; 83:505-522. [PMID: 34334399 DOI: 10.3233/jad-210404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This article aims to reevaluate our approach to female vulnerability to Alzheimer's disease (AD) and put forth a new hypothesis considering how sex differences in the locus coeruleus-noradrenaline (LC-NA) structure and function could account for why females are more likely to develop AD. We specifically focus our attention on locus coeruleus (LC) morphology, the paucity of estrogens, neuroinflammation, blood-brain barrier permeability, apolipoprotein ɛ4 polymorphism (APOEɛ4), and cognitive reserve. The role of the LC-NA system and sex differences are two of the most rapidly emerging topics in AD research. Current literature either investigates the LC due to it being one of the first brain areas to develop AD pathology or acknowledges the neuroprotective effects of estrogens and how the loss of these female hormones have the capacity to contribute to the sex differences seen in AD; however, existing research has neglected to concurrently examine these two rationales and therefore leaving our hypothesis undetermined. Collectively, this article should assist in alleviating current challenges surrounding female AD by providing thought-provoking connections into the interrelationship between the disruption of the female LC-NA system, the decline of estrogens, and AD vulnerability. It is therefore likely that treatment for this heterogeneous disease may need to be distinctly developed for females and males separately, and may require a precision medicine approach.
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Affiliation(s)
- Alison M Luckey
- Lab for Clinical & Integrative Neuroscience, School of Psychology, Trinity College Dublin, Dublin, Ireland
| | - Ian H Robertson
- Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland
| | - Brian Lawlor
- Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland
| | - Anusha Mohan
- Lab for Clinical & Integrative Neuroscience, School of Psychology, Trinity College Dublin, Dublin, Ireland
| | - Sven Vanneste
- Lab for Clinical & Integrative Neuroscience, School of Psychology, Trinity College Dublin, Dublin, Ireland.,Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland.,Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
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21
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Eskildsen SF, Iranzo A, Stokholm MG, Stær K, Østergaard K, Serradell M, Otto M, Svendsen KB, Garrido A, Vilas D, Borghammer P, Santamaria J, Møller A, Gaig C, Brooks DJ, Tolosa E, Østergaard L, Pavese N. Impaired cerebral microcirculation in isolated REM sleep behaviour disorder. Brain 2021; 144:1498-1508. [PMID: 33880533 DOI: 10.1093/brain/awab054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/19/2020] [Accepted: 12/09/2020] [Indexed: 01/18/2023] Open
Abstract
During the prodromal period of Parkinson's disease and other α-synucleinopathy-related parkinsonisms, neurodegeneration is thought to progressively affect deep brain nuclei, such as the locus coeruleus, caudal raphe nucleus, substantia nigra, and the forebrain nucleus basalis of Meynert. Besides their involvement in the regulation of mood, sleep, behaviour, and memory functions, these nuclei also innervate parenchymal arterioles and capillaries throughout the cortex, possibly to ensure that oxygen supplies are adjusted according to the needs of neural activity. The aim of this study was to examine whether patients with isolated REM sleep behaviour disorder, a parasomnia considered to be a prodromal phenotype of α-synucleinopathies, reveal microvascular flow disturbances consistent with disrupted central blood flow control. We applied dynamic susceptibility contrast MRI to characterize the microscopic distribution of cerebral blood flow in the cortex of 20 polysomnographic-confirmed patients with isolated REM sleep behaviour disorder (17 males, age range: 54-77 years) and 25 healthy matched controls (25 males, age range: 58-76 years). Patients and controls were cognitively tested by Montreal Cognitive Assessment and Mini Mental State Examination. Results revealed profound hypoperfusion and microvascular flow disturbances throughout the cortex in patients compared to controls. In patients, the microvascular flow disturbances were seen in cortical areas associated with language comprehension, visual processing and recognition and were associated with impaired cognitive performance. We conclude that cortical blood flow abnormalities, possibly related to impaired neurogenic control, are present in patients with isolated REM sleep behaviour disorder and associated with cognitive dysfunction. We hypothesize that pharmacological restoration of perivascular neurotransmitter levels could help maintain cognitive function in patients with this prodromal phenotype of parkinsonism.
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Affiliation(s)
- Simon F Eskildsen
- Center of Functionally Integrative Neuroscience and MINDLab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Alex Iranzo
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Morten G Stokholm
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Kristian Stær
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Karen Østergaard
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Mónica Serradell
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Marit Otto
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Alicia Garrido
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Dolores Vilas
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Per Borghammer
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Joan Santamaria
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Arne Møller
- Center of Functionally Integrative Neuroscience and MINDLab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Carles Gaig
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - David J Brooks
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark.,Translational and Clinical Research Institute, Newcastle University, England, UK
| | - Eduardo Tolosa
- Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain.,Parkinson disease and Movement Disorders Unit, Neurology Service, Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Neuroradiology Research Unit, Department of Radiology, Aarhus University Hospital, Denmark
| | - Nicola Pavese
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark.,Translational and Clinical Research Institute, Newcastle University, England, UK
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22
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Bell M, Zempel H. SH-SY5Y-derived neurons: a human neuronal model system for investigating TAU sorting and neuronal subtype-specific TAU vulnerability. Rev Neurosci 2021; 33:1-15. [PMID: 33866701 DOI: 10.1515/revneuro-2020-0152] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/06/2021] [Indexed: 11/15/2022]
Abstract
The microtubule-associated protein (MAP) TAU is mainly sorted into the axon of healthy brain neurons. Somatodendritic missorting of TAU is a pathological hallmark of many neurodegenerative diseases, including Alzheimer's disease (AD). Cause, consequence and (patho)physiological mechanisms of TAU sorting and missorting are understudied, in part also because of the lack of readily available human neuronal model systems. The human neuroblastoma cell line SH-SY5Y is widely used for studying TAU physiology and TAU-related pathology in AD and related tauopathies. SH-SY5Y cells can be differentiated into neuron-like cells (SH-SY5Y-derived neurons) using various substances. This review evaluates whether SH-SY5Y-derived neurons are a suitable model for (i) investigating intracellular TAU sorting in general, and (ii) with respect to neuron subtype-specific TAU vulnerability. (I) SH-SY5Y-derived neurons show pronounced axodendritic polarity, high levels of axonally localized TAU protein, expression of all six human brain isoforms and TAU phosphorylation similar to the human brain. As SH-SY5Y cells are highly proliferative and readily accessible for genetic engineering, stable transgene integration and leading-edge genome editing are feasible. (II) SH-SY5Y-derived neurons display features of subcortical neurons early affected in many tauopathies. This allows analyzing brain region-specific differences in TAU physiology, also in the context of differential vulnerability to TAU pathology. However, several limitations should be considered when using SH-SY5Y-derived neurons, e.g., the lack of clearly defined neuronal subtypes, or the difficulty of mimicking age-related tauopathy risk factors in vitro. In brief, this review discusses the suitability of SH-SY5Y-derived neurons for investigating TAU (mis)sorting mechanisms and neuron-specific TAU vulnerability in disease paradigms.
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Affiliation(s)
- Michael Bell
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931Cologne, Germany
| | - Hans Zempel
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931Cologne, Germany
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23
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Gezalian MM, Mangiacotti L, Rajput P, Sparrow N, Schlick K, Lahiri S. Cerebrovascular and neurological perspectives on adrenoceptor and calcium channel modulating pharmacotherapies. J Cereb Blood Flow Metab 2021; 41:693-706. [PMID: 33210576 PMCID: PMC7983505 DOI: 10.1177/0271678x20972869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 02/02/2023]
Abstract
Adrenoceptor and calcium channel modulating medications are widely used in clinical practice for acute neurological and systemic conditions. It is generally assumed that the cerebrovascular effects of these drugs mirror that of their systemic effects - and this is reflected in how these medications are currently used in clinical practice. However, recent research suggests that there are distinct cerebrovascular-specific effects of these medications that are related to the unique characteristics of the cerebrovascular anatomy including the regional heterogeneity in density and distribution of adrenoceptor subtypes and calcium channels along the cerebrovasculature. In this review, we critically evaluate existing basic science and clinical research to discuss known and putative interactions between adrenoceptor and calcium channel modulating pharmacotherapies, the neurovascular unit, and cerebrovascular anatomy. In doing so, we provide a rationale for selecting vasoactive medications based on lesion location and lay a foundation for future investigations that will define neuroprotective paradigms of adrenoceptor and calcium channel modulating therapies to improve neurological outcomes in acute neurological and systemic disorders.
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Affiliation(s)
- Michael M Gezalian
- Departments of Neurology and Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Luigi Mangiacotti
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Padmesh Rajput
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Nicklaus Sparrow
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Konrad Schlick
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Shouri Lahiri
- Departments of Neurology, Neurosurgery, and Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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24
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Mervin LH, Mitricheva E, Logothetis NK, Bifone A, Bender A, Noori HR. Neurochemical underpinning of hemodynamic response to neuropsychiatric drugs: A meta- and cluster analysis of preclinical studies. J Cereb Blood Flow Metab 2021; 41:874-885. [PMID: 32281457 PMCID: PMC7983335 DOI: 10.1177/0271678x20916003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/26/2020] [Accepted: 03/04/2020] [Indexed: 11/30/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is an extensively used method for the investigation of normal and pathological brain function. In particular, fMRI has been used to characterize spatiotemporal hemodynamic response to pharmacological challenges as a non-invasive readout of neuronal activity. However, the mechanisms underlying regional signal changes are yet unclear. In this study, we use a meta-analytic approach to converge data from microdialysis experiments with relative cerebral blood volume (rCBV) changes following acute administration of neuropsychiatric drugs in adult male rats. At whole-brain level, the functional response patterns show very weak correlation with neurochemical alterations, while for numerous brain areas a strong positive correlation with noradrenaline release exists. At a local scale of individual brain regions, the rCBV response to neurotransmitters is anatomically heterogeneous and, importantly, based on a complex interplay of different neurotransmitters that often exert opposing effects, thus providing a mechanism for regulating and fine tuning hemodynamic responses in specific regions.
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Affiliation(s)
- Lewis H Mervin
- Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Ekaterina Mitricheva
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Nikos K Logothetis
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK
| | - Angelo Bifone
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
- Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Andreas Bender
- Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Hamid R Noori
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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25
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Fischer T, Prey J, Eschholz L, Rotermund N, Lohr C. Norepinephrine-Induced Calcium Signaling and Store-Operated Calcium Entry in Olfactory Bulb Astrocytes. Front Cell Neurosci 2021; 15:639754. [PMID: 33833669 PMCID: PMC8021869 DOI: 10.3389/fncel.2021.639754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/02/2021] [Indexed: 11/30/2022] Open
Abstract
It is well-established that astrocytes respond to norepinephrine with cytosolic calcium rises in various brain areas, such as hippocampus or neocortex. However, less is known about the effect of norepinephrine on olfactory bulb astrocytes. In the present study, we used confocal calcium imaging and immunohistochemistry in mouse brain slices of the olfactory bulb, a brain region with a dense innervation of noradrenergic fibers, to investigate the calcium signaling evoked by norepinephrine in astrocytes. Our results show that application of norepinephrine leads to a cytosolic calcium rise in astrocytes which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. In addition, store-operated calcium entry (SOCE) contributes to the late phase of the response. Antagonists of both α1- and α2-adrenergic receptors, but not β-receptors, largely reduce the adrenergic calcium response, indicating that both α-receptor subtypes mediate norepinephrine-induced calcium transients in olfactory bulb astrocytes, whereas β-receptors do not contribute to the calcium transients.
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Affiliation(s)
- Timo Fischer
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Jessica Prey
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Lena Eschholz
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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26
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Wahis J, Holt MG. Astrocytes, Noradrenaline, α1-Adrenoreceptors, and Neuromodulation: Evidence and Unanswered Questions. Front Cell Neurosci 2021; 15:645691. [PMID: 33716677 PMCID: PMC7947346 DOI: 10.3389/fncel.2021.645691] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/03/2021] [Indexed: 12/27/2022] Open
Abstract
Noradrenaline is a major neuromodulator in the central nervous system (CNS). It is released from varicosities on neuronal efferents, which originate principally from the main noradrenergic nuclei of the brain - the locus coeruleus - and spread throughout the parenchyma. Noradrenaline is released in response to various stimuli and has complex physiological effects, in large part due to the wide diversity of noradrenergic receptors expressed in the brain, which trigger diverse signaling pathways. In general, however, its main effect on CNS function appears to be to increase arousal state. Although the effects of noradrenaline have been researched extensively, the majority of studies have assumed that noradrenaline exerts its effects by acting directly on neurons. However, neurons are not the only cells in the CNS expressing noradrenaline receptors. Astrocytes are responsive to a range of neuromodulators - including noradrenaline. In fact, noradrenaline evokes robust calcium transients in astrocytes across brain regions, through activation of α1-adrenoreceptors. Crucially, astrocytes ensheath neurons at synapses and are known to modulate synaptic activity. Hence, astrocytes are in a key position to relay, or amplify, the effects of noradrenaline on neurons, most notably by modulating inhibitory transmission. Based on a critical appraisal of the current literature, we use this review to argue that a better understanding of astrocyte-mediated noradrenaline signaling is therefore essential, if we are ever to fully understand CNS function. We discuss the emerging concept of astrocyte heterogeneity and speculate on how this might impact the noradrenergic modulation of neuronal circuits. Finally, we outline possible experimental strategies to clearly delineate the role(s) of astrocytes in noradrenergic signaling, and neuromodulation in general, highlighting the urgent need for more specific and flexible experimental tools.
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Affiliation(s)
- Jérôme Wahis
- Laboratory of Glia Biology, VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, Leuven, Belgium
| | - Matthew G. Holt
- Laboratory of Glia Biology, VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, Leuven, Belgium
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27
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Matchett BJ, Grinberg LT, Theofilas P, Murray ME. The mechanistic link between selective vulnerability of the locus coeruleus and neurodegeneration in Alzheimer's disease. Acta Neuropathol 2021; 141:631-650. [PMID: 33427939 PMCID: PMC8043919 DOI: 10.1007/s00401-020-02248-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/20/2020] [Accepted: 11/21/2020] [Indexed: 01/24/2023]
Abstract
Alzheimer's disease (AD) is neuropathologically characterized by the intracellular accumulation of hyperphosphorylated tau and the extracellular deposition of amyloid-β plaques, which affect certain brain regions in a progressive manner. The locus coeruleus (LC), a small nucleus in the pons of the brainstem, is widely recognized as one of the earliest sites of neurofibrillary tangle formation in AD. Patients with AD exhibit significant neuronal loss in the LC, resulting in a marked reduction of its size and function. The LC, which vastly innervates several regions of the brain, is the primary source of the neurotransmitter norepinephrine (NE) in the central nervous system. Considering that NE is a major modulator of behavior, contributing to neuroprotection and suppression of neuroinflammation, degeneration of the LC in AD and the ultimate dysregulation of the LC-NE system has detrimental effects in the brain. In this review, we detail the neuroanatomy and function of the LC, its essential role in neuroprotection, and how this is dysregulated in AD. We discuss AD-related neuropathologic changes in the LC and mechanisms by which LC neurons are selectively vulnerable to insult. Further, we elucidate the neurotoxic effects of LC de-innervation both locally and at projection sites, and how this augments disease pathology, progression and severity. We summarize how preservation of the LC-NE system could be used in the treatment of AD and other neurodegenerative diseases affected by LC degeneration.
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Affiliation(s)
- Billie J. Matchett
- Neuropathology Laboratory, Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Lea T. Grinberg
- Memory and Aging Center, Department of Neurology, University of California, 675 Nelson Rising Lane, San Francisco, CA 94158 USA
| | - Panos Theofilas
- Memory and Aging Center, Department of Neurology, University of California, 675 Nelson Rising Lane, San Francisco, CA, 94158, USA.
| | - Melissa E. Murray
- Neuropathology Laboratory, Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA
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28
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Azizi SA. Monoamines: Dopamine, Norepinephrine, and Serotonin, Beyond Modulation, "Switches" That Alter the State of Target Networks. Neuroscientist 2020; 28:121-143. [PMID: 33292070 DOI: 10.1177/1073858420974336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
How do monoamines influence the perceptual and behavioral aspects of brain function? A library of information regarding the genetic, molecular, cellular, and function of monoamines in the nervous system and other organs has accumulated. We briefly review monoamines' anatomy and physiology and discuss their effects on the target neurons and circuits. Monoaminergic cells in the brain stem receive inputs from sensory, limbic, and prefrontal areas and project extensively to the forebrain and hindbrain. We review selected studies on molecular, cellular, and electrophysiological effects of monoamines on the brain's target areas. The idea is that monoamines, by reversibly modulating the "primary" information processing circuits, regulate and switch the functions of brain networks and can reversibly alter the "brain states," such as consciousness, emotions, and movements. Monoamines, as the drivers of normal motor and sensory brain operations, including housekeeping, play essential roles in pathogenesis of neuropsychiatric diseases.
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Affiliation(s)
- Sayed Ausim Azizi
- Department of Neurology, Global Neuroscience Institute, Chester, PA, USA
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29
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Michalicova A, Majerova P, Kovac A. Tau Protein and Its Role in Blood-Brain Barrier Dysfunction. Front Mol Neurosci 2020; 13:570045. [PMID: 33100967 PMCID: PMC7554615 DOI: 10.3389/fnmol.2020.570045] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022] Open
Abstract
The blood-brain barrier (BBB) plays a crucial role in maintaining the specialized microenvironment of the central nervous system (CNS). In aging, the stability of the BBB declines and the permeability increases. The list of CNS pathologies involving BBB dysfunction is growing. The opening of the BBB and subsequent infiltration of serum components to the brain can lead to a host of processes resulting in progressive synaptic, neuronal dysfunction, and detrimental neuroinflammatory changes. Such processes have been implicated in different diseases, including vascular dementia, stroke, Alzheimer's disease (AD), Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, hypoxia, ischemia, and diabetes mellitus. The BBB damage is also observed in tauopathies that lack amyloid-β overproduction, suggesting a role for tau in BBB damage. Tauopathies represent a heterogeneous group of around 20 different neurodegenerative diseases characterized by abnormal deposition of the MAPT in cells of the nervous system. Neuropathology of tauopathies is defined as intracellular accumulation of neurofibrillary tangles (NFTs) consisting of aggregated hyper- and abnormal phosphorylation of tau protein and neuroinflammation. Disruption of the BBB found in tauopathies is driven by chronic neuroinflammation. Production of pro-inflammatory signaling molecules such as cytokines, chemokines, and adhesion molecules by glial cells, neurons, and endothelial cells determine the integrity of the BBB and migration of immune cells into the brain. The inflammatory processes promote structural changes in capillaries such as fragmentation, thickening, atrophy of pericytes, accumulation of laminin in the basement membrane, and increased permeability of blood vessels to plasma proteins. Here, we summarize the knowledge about the role of tau protein in BBB structural and functional changes.
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Affiliation(s)
- Alena Michalicova
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Petra Majerova
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Andrej Kovac
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia.,Department of Pharmacology and Toxicology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
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30
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Pacholko AG, Wotton CA, Bekar LK. Astrocytes-The Ultimate Effectors of Long-Range Neuromodulatory Networks? Front Cell Neurosci 2020; 14:581075. [PMID: 33192327 PMCID: PMC7554522 DOI: 10.3389/fncel.2020.581075] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/07/2020] [Indexed: 11/21/2022] Open
Abstract
It was long thought that astrocytes, given their lack of electrical signaling, were not involved in communication with neurons. However, we now know that one astrocyte on average maintains and regulates the extracellular neurotransmitter and potassium levels of more than 140,000 synapses, both excitatory and inhibitory, within their individual domains, and form a syncytium that can propagate calcium waves to affect distant cells via release of “gliotransmitters” such as glutamate, ATP, or adenosine. Neuromodulators can affect signal-to-noise and frequency transmission within cortical circuits by effects on inhibition, allowing for the filtering of relevant vs. irrelevant stimuli. Moreover, synchronized “resting” and desynchronized “activated” brain states are gated by short bursts of high-frequency neuromodulatory activity, highlighting the need for neuromodulation that is robust, rapid, and far-reaching. As many neuromodulators are released in a volume manner where degradation/uptake and the confines of the complex CNS limit diffusion distance, we ask the question—are astrocytes responsible for rapidly extending neuromodulator actions to every synapse? Neuromodulators are known to influence transitions between brain states, leading to control over plasticity, responses to salient stimuli, wakefulness, and sleep. These rapid and wide-spread state transitions demand that neuromodulators can simultaneously influence large and diverse regions in a manner that should be impossible given the limitations of simple diffusion. Intriguingly, astrocytes are ideally situated to amplify/extend neuromodulator effects over large populations of synapses given that each astrocyte can: (1) ensheath a large number of synapses; (2) release gliotransmitters (glutamate/ATP/adenosine) known to affect inhibition; (3) regulate extracellular potassium that can affect excitability and excitation/inhibition balance; and (4) express receptors for all neuromodulators. In this review article, we explore the hypothesis that astrocytes extend and amplify neuromodulatory influences on neuronal networks via alterations in calcium dynamics, the release of gliotransmitters, and potassium homeostasis. Given that neuromodulatory networks are at the core of our sleep-wake cycle and behavioral states, and determine how we interact with our environment, this review article highlights the importance of basic astrocyte function in homeostasis, general cognition, and psychiatric disorders.
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Affiliation(s)
- Anthony G Pacholko
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Caitlin A Wotton
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Lane K Bekar
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada
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31
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Giorgi FS, Galgani A, Puglisi-Allegra S, Limanaqi F, Busceti CL, Fornai F. Locus Coeruleus and neurovascular unit: From its role in physiology to its potential role in Alzheimer's disease pathogenesis. J Neurosci Res 2020; 98:2406-2434. [PMID: 32875628 DOI: 10.1002/jnr.24718] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/26/2020] [Accepted: 08/08/2020] [Indexed: 12/15/2022]
Abstract
Locus coeruleus (LC) is the main noradrenergic (NA) nucleus of the central nervous system. LC degenerates early during Alzheimer's disease (AD) and NA loss might concur to AD pathogenesis. Aside from neurons, LC terminals provide dense innervation of brain intraparenchymal arterioles/capillaries, and NA modulates astrocyte functions. The term neurovascular unit (NVU) defines the strict anatomical/functional interaction occurring between neurons, glial cells, and brain vessels. NVU plays a fundamental role in coupling the energy demand of activated brain regions with regional cerebral blood flow, it includes the blood-brain barrier (BBB), plays an active role in neuroinflammation, and participates also to the glymphatic system. NVU alteration is involved in AD pathophysiology through several mechanisms, mainly related to a relative oligoemia in activated brain regions and impairment of structural and functional BBB integrity, which contributes also to the intracerebral accumulation of insoluble amyloid. We review the existing data on the morphological features of LC-NA innervation of the NVU, as well as its contribution to neurovascular coupling and BBB proper functioning. After introducing the main experimental data linking LC with AD, which have repeatedly shown a key role of neuroinflammation and increased amyloid plaque formation, we discuss the potential mechanisms by which the loss of NVU modulation by LC might contribute to AD pathogenesis. Surprisingly, thus far not so many studies have tested directly these mechanisms in models of AD in which LC has been lesioned experimentally. Clarifying the interaction of LC with NVU in AD pathogenesis may disclose potential therapeutic targets for AD.
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Affiliation(s)
- Filippo Sean Giorgi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.,Neurology Unit, Pisa University Hospital, Pisa, Italy
| | | | | | - Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.,I.R.C.C.S. I.N.M. Neuromed, Pozzilli, Italy
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32
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Pamphlett R, Mak R, Lee J, Buckland ME, Harding AJ, Kum Jew S, Paterson DJ, Jones MWM, Lay PA. Concentrations of toxic metals and essential trace elements vary among individual neurons in the human locus ceruleus. PLoS One 2020; 15:e0233300. [PMID: 32428015 PMCID: PMC7237016 DOI: 10.1371/journal.pone.0233300] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/02/2020] [Indexed: 12/17/2022] Open
Abstract
Objective Damage to locus ceruleus neurons could play a part in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis because of impairment of the blood-brain barrier and enhanced neuroinflammation. The locus ceruleus has connections throughout the brain and spinal cord, so the characteristic widespread multifocal pathology in these disorders could be due to damage to different subsets of locus ceruleus neurons. Previous studies have shown that only certain locus ceruleus neurons accumulate the neurotoxic metal mercury. To find out if concentrations of other toxic metals or of essential trace elements also vary between individual locus ceruleus neurons, we used synchrotron X-ray fluorescence microscopy on frozen sections of locus ceruleus neurons taken from people with multiple sclerosis, in whom the locus ceruleus is structurally intact. Materials and methods Paraffin embedded sections containing the locus ceruleus from seven people with multiple sclerosis were stained with autometallography that demonstrates accumulations of mercury, silver and bismuth. These were compared to maps of multiple elements obtained from frozen sections of locus ceruleus neurons from the same people using X-ray fluorescence microscopy. Neurons in the anterior pons from three of these donors were used as internal controls. Results Autometallography staining was observed in scattered locus ceruleus neurons from three of the seven donors. X-ray fluorescence microscopy showed variations among individual locus ceruleus neurons in levels of mercury, selenium, iron, copper, lead, bromine, and rubidium. Variations between donors of locus ceruleus neuronal average levels of mercury, iron, copper, and bromine were also detected. Anterior pons neurons contained no mercury, had varied levels of iron, and had lower copper levels than locus ceruleus neurons. Conclusions Individual human locus ceruleus neurons contain varying levels of toxic metals and essential trace elements. In contrast, most toxic metals are absent or at low levels in nearby anterior pons neurons. The locus ceruleus plays a role in numerous central nervous system functions, including maintaining the blood-brain-barrier and limiting neuroinflammation. Toxic metals, or alterations in essential trace metals within individual locus ceruleus neurons, could be one factor determining the non-random destruction of locus ceruleus neurons in normal aging and neurodegenerative diseases, and subsequently the sites of the widespread multifocal central nervous system pathology in these disorders.
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Affiliation(s)
- Roger Pamphlett
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
- * E-mail:
| | - Rachel Mak
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
| | - Joonsup Lee
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
| | - Michael E. Buckland
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
| | - Antony J. Harding
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
| | - Stephen Kum Jew
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
| | | | | | - Peter A. Lay
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
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Collapsibility of the internal jugular veins in the lateral decubitus body position: A potential protective role of the cerebral venous outflow against neurodegeneration. Med Hypotheses 2019; 133:109397. [DOI: 10.1016/j.mehy.2019.109397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/16/2019] [Accepted: 09/10/2019] [Indexed: 01/26/2023]
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Hirunpattarasilp C, Attwell D, Freitas F. The role of pericytes in brain disorders: from the periphery to the brain. J Neurochem 2019; 150:648-665. [PMID: 31106417 DOI: 10.1111/jnc.14725] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/15/2019] [Accepted: 05/15/2019] [Indexed: 12/13/2022]
Abstract
It is becoming increasingly apparent that disorders of the brain microvasculature contribute to many neurological disorders. In recent years it has become clear that a major player in these events is the capillary pericyte which, in the brain, is now known to control the blood-brain barrier, regulate blood flow, influence immune cell entry and be crucial for angiogenesis. In this review we consider the under-explored possibility that peripheral diseases which affect the microvasculature, such as hypertension, kidney disease and diabetes, produce central nervous system (CNS) dysfunction by mechanisms affecting capillary pericytes within the CNS. We highlight how cellular messengers produced peripherally can act via signalling pathways within CNS pericytes to reshape blood vessels, restrict blood flow or compromise blood-brain barrier function, thus causing neuronal dysfunction. Increased understanding of how renin-angiotensin, Rho-kinase and PDGFRβ signalling affect CNS pericytes may suggest novel therapeutic approaches to reducing the CNS effects of peripheral disorders.
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Affiliation(s)
- Chanawee Hirunpattarasilp
- Department of Neuroscience, Andrew Huxley Building, University College London, Physiology & Pharmacology, Gower Street, London, UK
| | - David Attwell
- Department of Neuroscience, Andrew Huxley Building, University College London, Physiology & Pharmacology, Gower Street, London, UK
| | - Felipe Freitas
- Department of Neuroscience, Andrew Huxley Building, University College London, Physiology & Pharmacology, Gower Street, London, UK
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On the existence of mechanoreceptors within the neurovascular unit of the mammalian brain. Brain Struct Funct 2019; 224:2247-2267. [PMID: 31190162 DOI: 10.1007/s00429-019-01863-3] [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: 11/30/2018] [Accepted: 03/16/2019] [Indexed: 10/26/2022]
Abstract
We describe a set of perivascular interneurons (PINs) with series of fibro-vesicular complexes (FVCs) throughout the gray matter of the adult rabbit and rat brains. PIN-FVCs are ubiquitous throughout the brain vasculature as detected in Golgi-impregnated specimens. Most PINs are small, aspiny cells with short or long (> 1 mm) axons that split and travel along arterial blood vessels. Upon ramification, axons form FVCs around the arising vascular branches; then, paired axons run parallel to the vessel wall until another ramification ensues, and a new FVC is formed. Cytologically, FVCs consist of clusters of perivascular bulbs (PVBs) encircling the precapillary and capillary wall surrounded by end-feet and the extracellular matrix of endothelial cells and pericytes. A PVB contains mitochondria, multivesicular bodies, and granules with a membranous core, similar to Meissner corpuscles and other mechanoreceptors. Some PVBs form asymmetrical, axo-spinous synapses with presumptive adjacent neurons. PINs appear to correspond to the type 1 nNOS-positive neurons whose FVCs co-label with markers of sensory fiber-terminals surrounded by astrocytic end-feet. The PIN is conserved in adult cats and rhesus monkey specimens. The location, ubiquity throughout the vasculature of the mammalian brain, and cytological organization of the PIN-FVCs suggests that it is a sensory receptor intrinsic to the mammalian neurovascular unit that corresponds to an afferent limb of the sensorimotor feed-back mechanism controlling local blood flow.
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How reliable is cerebral blood flow to map changes in neuronal activity? Auton Neurosci 2019; 217:71-79. [PMID: 30744905 DOI: 10.1016/j.autneu.2019.01.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/17/2018] [Accepted: 01/27/2019] [Indexed: 02/06/2023]
Abstract
Neuroimaging techniques, such as functional MRI, map brain activity through hemodynamic-based signals, and are invaluable diagnostic tools in several neurological disorders such as stroke and dementia. Hemodynamic signals are normally precisely related to the underlying neuronal activity through neurovascular coupling mechanisms that ensure the supply of blood, glucose and oxygen to neurons at work. The knowledge of neurovascular coupling has greatly advanced over the last 30 years, it involves multifaceted interactions between excitatory and inhibitory neurons, astrocytes, and the microvessels. While the tight relationship between blood flow and neuronal activity forms a fundamental brain function, whether neurovascular coupling mechanisms are reliable across physiological and pathological conditions has been questioned. In this review, we interrogate the relationship between blood flow and neuronal activity during activation of different brain pathways: a sensory stimulation driven by glutamate, and stimulation of neuromodulatory pathways driven by acetylcholine or noradrenaline, and we compare the underlying neurovascular coupling mechanisms. We further question if neurovascular coupling mechanisms are affected by changing brain states, as seen in behavioral conditions of sleep, wakefulness, attention and in pathological conditions. Finally, we provide a short overview of how alterations of the brain vasculature could compromise the reliability of neurovascular coupling. Overall, while neurovascular coupling requires activation of common signalling pathways, alternate unique cascades exist depending on the activated pathways. Further studies are needed to fully elucidate the alterations in neurovascular coupling across brain states and pathological conditions.
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Roles of tau pathology in the locus coeruleus (LC) in age-associated pathophysiology and Alzheimer’s disease pathogenesis: Potential strategies to protect the LC against aging. Brain Res 2019; 1702:17-28. [DOI: 10.1016/j.brainres.2017.12.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 11/21/2017] [Accepted: 12/19/2017] [Indexed: 12/11/2022]
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Kelly SC, McKay EC, Beck JS, Collier TJ, Dorrance AM, Counts SE. Locus Coeruleus Degeneration Induces Forebrain Vascular Pathology in a Transgenic Rat Model of Alzheimer's Disease. J Alzheimers Dis 2019; 70:371-388. [PMID: 31177220 PMCID: PMC6929678 DOI: 10.3233/jad-190090] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Noradrenergic locus coeruleus (LC) neuron loss is a significant feature of mild cognitive impairment and Alzheimer's disease (AD). The LC is the primary source of norepinephrine in the forebrain, where it modulates attention and memory in vulnerable cognitive regions such as prefrontal cortex (PFC) and hippocampus. Furthermore, LC-mediated norepinephrine signaling is thought to play a role in blood-brain barrier (BBB) maintenance and neurovascular coupling, suggesting that LC degeneration may impact the high comorbidity of cerebrovascular disease and AD. However, the extent to which LC projection system degeneration influences vascular pathology is not fully understood. To address this question in vivo, we stereotactically lesioned LC projection neurons innervating the PFC of six-month-old Tg344-19 AD rats using the noradrenergic immunotoxin, dopamine-β-hydroxylase IgG-saporin (DBH-sap), or an untargeted control IgG-saporin (IgG-sap). DBH-sap-lesioned animals performed significantly worse than IgG-sap animals on the Barnes maze task in measures of both spatial and working memory. DBH-sap-lesioned rats also displayed increased amyloid and inflammation pathology compared to IgG-sap controls. However, we also discovered prominent parenchymal albumin extravasation with DBH-sap lesions indicative of BBB breakdown. Moreover, microvessel wall-to-lumen ratios were increased in the PFC of DBH-sap compared to IgG-sap rats, suggesting that LC deafferentation results in vascular remodeling. Finally, we noted an early emergence of amyloid angiopathy in the DBH-sap-lesioned Tg344-19 AD rats. Taken together, these data indicate that LC projection system degeneration is a nexus lesion that compromises both vascular and neuronal function in cognitive brain areas during the prodromal stages of AD.
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Affiliation(s)
- Sarah C. Kelly
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, USA
| | - Erin C. McKay
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | - John S. Beck
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
| | - Timothy J. Collier
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | - Anne M. Dorrance
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Scott E. Counts
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Family Medicine, Michigan State University, Grand Rapids, MI, USA
- Hauenstein Neurosciences Center, Mercy Health Saint Mary’s Hospital, Grand Rapids, MI, USA
- Michigan Alzheimer’s Disease Core Center, Ann Arbor, MI, USA
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Østergaard L, Jørgensen MB, Knudsen GM. Low on energy? An energy supply-demand perspective on stress and depression. Neurosci Biobehav Rev 2018; 94:248-270. [DOI: 10.1016/j.neubiorev.2018.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/09/2018] [Accepted: 08/13/2018] [Indexed: 12/17/2022]
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40
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Chakravarthy S, Balasubramani PP, Mandali A, Jahanshahi M, Moustafa AA. The many facets of dopamine: Toward an integrative theory of the role of dopamine in managing the body's energy resources. Physiol Behav 2018; 195:128-141. [DOI: 10.1016/j.physbeh.2018.06.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 05/07/2018] [Accepted: 06/20/2018] [Indexed: 02/07/2023]
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41
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Kolinko Y, Kralickova M, Tonar Z. The impact of pericytes on the brain and approaches for their morphological analysis. J Chem Neuroanat 2018; 91:35-45. [DOI: 10.1016/j.jchemneu.2018.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/10/2018] [Accepted: 04/15/2018] [Indexed: 12/15/2022]
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42
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Coggan JS, Keller D, Calì C, Lehväslaiho H, Markram H, Schürmann F, Magistretti PJ. Norepinephrine stimulates glycogenolysis in astrocytes to fuel neurons with lactate. PLoS Comput Biol 2018; 14:e1006392. [PMID: 30161133 PMCID: PMC6160207 DOI: 10.1371/journal.pcbi.1006392] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 09/27/2018] [Accepted: 07/24/2018] [Indexed: 12/20/2022] Open
Abstract
The mechanism of rapid energy supply to the brain, especially to accommodate the heightened metabolic activity of excited states, is not well-understood. We explored the role of glycogen as a fuel source for neuromodulation using the noradrenergic stimulation of glia in a computational model of the neural-glial-vasculature ensemble (NGV). The detection of norepinephrine (NE) by the astrocyte and the coupled cAMP signal are rapid and largely insensitive to the distance of the locus coeruleus projection release sites from the glia, implying a diminished impact for volume transmission in high affinity receptor transduction systems. Glucosyl-conjugated units liberated from glial glycogen by NE-elicited cAMP second messenger transduction winds sequentially through the glycolytic cascade, generating robust increases in NADH and ATP before pyruvate is finally transformed into lactate. This astrocytic lactate is rapidly exported by monocarboxylate transporters to the associated neuron, demonstrating that the astrocyte-to-neuron lactate shuttle activated by glycogenolysis is a likely fuel source for neuromodulation and enhanced neural activity. Altogether, the energy supply for both astrocytes and neurons can be supplied rapidly by glycogenolysis upon neuromodulatory stimulus. Although efficient compared to computers, the human brain utilizes energy at 10-fold the rate of other organs by mass. How the brain is supplied with sufficient on-demand energy to support its activity in the absence of neuronal storage capacity remains unknown. Neurons are not capable of meeting their own energy requirements, instead energy supply in the brain is managed by an oligocellular cartel composed of neurons, glia and the local vasculature (NGV), wherein glia can provide the ergogenic metabolite lactate to the neuron in a process called the astrocyte-to-neuron shuttle (ANLS). The only means of energy storage in the brain is glycogen, a polymerized form of glucose that is localized largely to astrocytes, but its exact role and conditions of use are not clear. In this computational model we show that neuromodulatory stimulation by norepinephrine induces astrocytes to recover glucosyl subunits from glycogen for use in a glycolytic process that favors the production of lactate. The ATP and NADH produced support metabolism in the astrocyte while the lactate is exported to feed the neuron. Thus, rapid energy demands by both neurons and glia in a stimulated brain can be met by glycogen mobilization.
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Affiliation(s)
- Jay S. Coggan
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- * E-mail: (JSC); (PJM)
| | - Daniel Keller
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Corrado Calì
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Heikki Lehväslaiho
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Henry Markram
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Felix Schürmann
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Pierre J. Magistretti
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
- * E-mail: (JSC); (PJM)
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Abstract
The blood-brain barrier (BBB) plays a vital role in the maintenance of brain homeostasis. It strictly restricts the passage of molecules from the brain vasculature into the brain via its high transendothelial electrical resistance and low paracellular and transcellular permeability. Specialized brain endothelial cells, astrocytes, pericytes, neurons, and microglia contribute synergistically to the functional properties of the BBB. Because of its complexity and relative inaccessibility, BBB research is fraught with difficulties. Most studies rely on animal or cell culture models, which are not able to fully recapitulate the properties of the human BBB. The recent development of three-dimensional (3D) microfluidic models of the BBB could address this issue. This chapter aims to provide an overview of the recent advances in modeling the BBB on microdevices, and illustrate important considerations for the design of such models. In addition, protocols for the fabrication of a 3D BBB microfluidic chip and BBB assessment experiments, including immunocytochemistry for analyzing cell morphology and protein marker expression, permeability assay, and calcium imaging for studying neuronal function as a measure of BBB integrity, are presented here. It is envisioned that continued advancements in microtechnology can lead to the creation of realistic in vivo-like BBB-on-chip models.
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Affiliation(s)
- Eunice Chin
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore
| | - Eyleen Goh
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore; Department of Research, National Neuroscience Institute, Singapore.
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44
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Zhu MY. Noradrenergic Modulation on Dopaminergic Neurons. Neurotox Res 2018; 34:848-859. [DOI: 10.1007/s12640-018-9889-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/05/2018] [Accepted: 03/08/2018] [Indexed: 12/24/2022]
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De Cicco V, Tramonti Fantozzi MP, Cataldo E, Barresi M, Bruschini L, Faraguna U, Manzoni D. Trigeminal, Visceral and Vestibular Inputs May Improve Cognitive Functions by Acting through the Locus Coeruleus and the Ascending Reticular Activating System: A New Hypothesis. Front Neuroanat 2018; 11:130. [PMID: 29358907 PMCID: PMC5766640 DOI: 10.3389/fnana.2017.00130] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/15/2017] [Indexed: 12/25/2022] Open
Abstract
It is known that sensory signals sustain the background discharge of the ascending reticular activating system (ARAS) which includes the noradrenergic locus coeruleus (LC) neurons and controls the level of attention and alertness. Moreover, LC neurons influence brain metabolic activity, gene expression and brain inflammatory processes. As a consequence of the sensory control of ARAS/LC, stimulation of a sensory channel may potential influence neuronal activity and trophic state all over the brain, supporting cognitive functions and exerting a neuroprotective action. On the other hand, an imbalance of the same input on the two sides may lead to an asymmetric hemispheric excitability, leading to an impairment in cognitive functions. Among the inputs that may drive LC neurons and ARAS, those arising from the trigeminal region, from visceral organs and, possibly, from the vestibular system seem to be particularly relevant in regulating their activity. The trigeminal, visceral and vestibular control of ARAS/LC activity may explain why these input signals: (1) affect sensorimotor and cognitive functions which are not directly related to their specific informational content; and (2) are effective in relieving the symptoms of some brain pathologies, thus prompting peripheral activation of these input systems as a complementary approach for the treatment of cognitive impairments and neurodegenerative disorders.
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Affiliation(s)
- Vincenzo De Cicco
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Maria P Tramonti Fantozzi
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | | | - Massimo Barresi
- Institut des Maladie Neurodégénératives, University of Bordeaux, Bordeaux, France
| | - Luca Bruschini
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Ugo Faraguna
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy.,Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Diego Manzoni
- Laboratory of Sensorimotor Integration, Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 928] [Impact Index Per Article: 154.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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Hall CN, Howarth C, Kurth-Nelson Z, Mishra A. Interpreting BOLD: towards a dialogue between cognitive and cellular neuroscience. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0348. [PMID: 27574302 DOI: 10.1098/rstb.2015.0348] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2016] [Indexed: 12/11/2022] Open
Abstract
Cognitive neuroscience depends on the use of blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to probe brain function. Although commonly used as a surrogate measure of neuronal activity, BOLD signals actually reflect changes in brain blood oxygenation. Understanding the mechanisms linking neuronal activity to vascular perfusion is, therefore, critical in interpreting BOLD. Advances in cellular neuroscience demonstrating differences in this neurovascular relationship in different brain regions, conditions or pathologies are often not accounted for when interpreting BOLD. Meanwhile, within cognitive neuroscience, the increasing use of high magnetic field strengths and the development of model-based tasks and analyses have broadened the capability of BOLD signals to inform us about the underlying neuronal activity, but these methods are less well understood by cellular neuroscientists. In 2016, a Royal Society Theo Murphy Meeting brought scientists from the two communities together to discuss these issues. Here, we consolidate the main conclusions arising from that meeting. We discuss areas of consensus about what BOLD fMRI can tell us about underlying neuronal activity, and how advanced modelling techniques have improved our ability to use and interpret BOLD. We also highlight areas of controversy in understanding BOLD and suggest research directions required to resolve these issues.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
| | - Clare Howarth
- Department of Psychology, University of Sheffield, Sheffield, UK
| | - Zebulun Kurth-Nelson
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, University College London, London, UK
| | - Anusha Mishra
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Pericytes impair capillary blood flow and motor function after chronic spinal cord injury. Nat Med 2017; 23:733-741. [PMID: 28459438 PMCID: PMC5716958 DOI: 10.1038/nm.4331] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 03/28/2017] [Indexed: 12/19/2022]
Abstract
Blood vessels in the central nervous system (CNS) are controlled by neuronal activity. For example, widespread vessel constriction (vessel tone) is induced by brainstem neurons that release the monoamines serotonin and noradrenaline, and local vessel dilation is induced by glutamatergic neuron activity. Here we examined how vessel tone adapts to the loss of neuron-derived monoamines after spinal cord injury (SCI) in rats. We find that, months after the imposition of SCI, the spinal cord below the site of injury is in a chronic state of hypoxia owing to paradoxical excess activity of monoamine receptors (5-HT1) on pericytes, despite the absence of monoamines. This monoamine-receptor activity causes pericytes to locally constrict capillaries, which reduces blood flow to ischemic levels. Receptor activation in the absence of monoamines results from the production of trace amines (such as tryptamine) by pericytes that ectopically express the enzyme aromatic L-amino acid decarboxylase (AADC), which synthesizes trace amines directly from dietary amino acids (such as tryptophan). Inhibition of monoamine receptors or of AADC, or even an increase in inhaled oxygen, produces substantial relief from hypoxia and improves motoneuron and locomotor function after SCI.
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Brain-Computer Interface-Based Communication in the Completely Locked-In State. PLoS Biol 2017; 15:e1002593. [PMID: 28141803 PMCID: PMC5283652 DOI: 10.1371/journal.pbio.1002593] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 12/27/2016] [Indexed: 12/13/2022] Open
Abstract
Despite partial success, communication has remained impossible for persons suffering from complete motor paralysis but intact cognitive and emotional processing, a state called complete locked-in state (CLIS). Based on a motor learning theoretical context and on the failure of neuroelectric brain–computer interface (BCI) communication attempts in CLIS, we here report BCI communication using functional near-infrared spectroscopy (fNIRS) and an implicit attentional processing procedure. Four patients suffering from advanced amyotrophic lateral sclerosis (ALS)—two of them in permanent CLIS and two entering the CLIS without reliable means of communication—learned to answer personal questions with known answers and open questions all requiring a “yes” or “no” thought using frontocentral oxygenation changes measured with fNIRS. Three patients completed more than 46 sessions spread over several weeks, and one patient (patient W) completed 20 sessions. Online fNIRS classification of personal questions with known answers and open questions using linear support vector machine (SVM) resulted in an above-chance-level correct response rate over 70%. Electroencephalographic oscillations and electrooculographic signals did not exceed the chance-level threshold for correct communication despite occasional differences between the physiological signals representing a “yes” or “no” response. However, electroencephalogram (EEG) changes in the theta-frequency band correlated with inferior communication performance, probably because of decreased vigilance and attention. If replicated with ALS patients in CLIS, these positive results could indicate the first step towards abolition of complete locked-in states, at least for ALS. "Locked in" patients suffering from advanced amyotrophic lateral sclerosis, with no reliable means of communication, can learn to answer questions requiring a “yes” or “no” thought using frontocentral oxygenation changes measurable by functional near-infrared spectroscopy. Despite scientific and technological advances, communication has remained impossible for persons suffering from complete motor paralysis but intact cognitive and emotional processing, a condition that is called completely locked-in state. Brain–computer interfaces based on neuroelectrical technology (like an electroencephalogram) have failed at providing patients in a completely locked-in state with means to communicate. Therefore, here we explored if a brain–computer interface based on functional near infrared spectroscopy (fNIRS)—which measures brain hemodynamic responses associated with neuronal activity—could overcome this barrier. Four patients suffering from advanced amyotrophic lateral sclerosis (ALS), two of them in permanent completely locked-in state and two entering the completely locked-in state without reliable means of communication, learned to answer personal questions with known answers and open questions requiring a “yes” or “no” by using frontocentral oxygenation changes measured with fNIRS. These results are, potentially, the first step towards abolition of completely locked-in states, at least for patients with ALS.
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