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Tran CHT, Peringod G, Gordon GR. Astrocytes Integrate Behavioral State and Vascular Signals during Functional Hyperemia. Neuron 2018; 100:1133-1148.e3. [PMID: 30482689 DOI: 10.1016/j.neuron.2018.09.045] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 06/25/2018] [Accepted: 09/24/2018] [Indexed: 01/17/2023]
Abstract
Dynamic changes in astrocyte free Ca2+ regulate synaptic signaling and local blood flow. Although astrocytes are poised to integrate signals from synapses and the vasculature to perform their functional roles, it remains unclear what dictates astrocyte responses during neurovascular coupling under realistic conditions. We examined peri-arteriole and peri-capillary astrocytes in the barrel cortex of active mice in response to sensory stimulation or volitional behaviors. We observed an AMPA and NMDA receptor-dependent elevation in astrocyte endfoot Ca2+ that followed functional hyperemia onset. This delayed astrocyte Ca2+ signal was dependent on the animal's action at the time of measurement as well as a neurovascular pathway that linked to endothelial-derived nitric oxide. A similar elevation in endfoot Ca2+ was evoked using vascular chemogenetics or optogenetics, and opto-stimulated dilation recruited the same nitric oxide pathway as functional hyperemia. These data show that behavioral state and microvasculature influence astrocyte Ca2+ in active mice. VIDEO ABSTRACT.
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Affiliation(s)
- Cam Ha T Tran
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Govind Peringod
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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Isolation and differential transcriptome of vascular smooth muscle cells and mid-capillary pericytes from the rat brain. Sci Rep 2018; 8:12272. [PMID: 30116021 PMCID: PMC6095852 DOI: 10.1038/s41598-018-30739-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 07/20/2018] [Indexed: 12/20/2022] Open
Abstract
Brain mural cells form a heterogeneous family which significantly contributes to the maintenance of the blood-brain barrier and regulation of the cerebral blood flow. Current procedures to isolate them cannot specifically separate their distinct subtypes, in particular vascular smooth muscle cells (VSMCs) and mid-capillary pericytes (mcPCs), which differ among others by their expression of smooth muscle actin (SMA). We herein describe an innovative method allowing SMA+ VSMCs and SMA− mcPCs to be freshly isolated from the rat cerebral cortex. Using differential RNA-Seq analysis, we then reveal the specific gene expression profile of each subtype. Our results refine the current description of the role of VSMCs in parenchymal cortical arterioles at the molecular level and provide a unique platform to identify the molecular mechanisms underlying the specific functions of mcPCs in the brain vasculature.
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Svane KC, Asis EK, Omelchenko A, Kunnath AJ, Brzustowicz LM, Silverstein SM, Firestein BL. d-Serine administration affects nitric oxide synthase 1 adaptor protein and DISC1 expression in sex-specific manner. Mol Cell Neurosci 2018; 89:20-32. [PMID: 29601869 DOI: 10.1016/j.mcn.2018.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 01/19/2023] Open
Abstract
Antipsychotic medications are inefficient at treating symptoms of schizophrenia (SCZ), and N-methyl d-aspartate receptor (NMDAR) agonists are potential therapeutic alternatives. As such, these agonists may act on different pathways and proteins altered in the brains of patients with SCZ than do antipsychotic medications. Here, we investigate the effects of administration of the antipsychotic haloperidol and NMDAR agonist d-serine on function and expression of three proteins that play significant roles in SCZ: nitric oxide synthase 1 adaptor protein (NOS1AP), dopamine D2 (D2) receptor, and disrupted in schizophrenia 1 (DISC1). We administered haloperidol or d-serine to male and female Sprague Dawley rats via intraperitoneal injection for 12 days and subsequently examined cortical expression of NOS1AP, D2 receptor, and DISC1. We found sex-specific effects of haloperidol and d-serine treatment on the expression of these proteins. Haloperidol significantly reduced expression of D2 receptor in male, but not female, rats. Conversely, d-serine reduced expression of NOS1AP in male rats and did not affect D2 receptor expression. d-serine treatment also reduced expression of DISC1 in male rats and increased DISC1 expression in female rats. As NOS1AP is overexpressed in the cortex of patients with SCZ and negatively regulates NMDAR signaling, we subsequently examined whether treatment with antipsychotics or NMDAR agonists can reverse the detrimental effects of NOS1AP overexpression in vitro as previously reported by our group. NOS1AP overexpression promotes reduced dendrite branching in vitro, and as such, we treated cortical neurons overexpressing NOS1AP with different antipsychotics (haloperidol, clozapine, fluphenazine) or d-serine for 24 h and determined the effects of these drugs on NOS1AP expression and dendrite branching. While antipsychotics did not affect NOS1AP protein expression or dendrite branching in vitro, d-serine reduced NOS1AP expression and rescued NOS1AP-mediated reductions in dendrite branching. Taken together, our data suggest that d-serine influences the function and expression of NOS1AP, D2 receptor, and DISC1 in a sex-specific manner and reverses the effects of NOS1AP overexpression on dendrite morphology.
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Affiliation(s)
- Kirsten C Svane
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA; Neuroscience Graduate Program, Rutgers, The State University of New Jersey, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Ericka-Kate Asis
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - Anton Omelchenko
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA; Neuroscience Graduate Program, Rutgers, The State University of New Jersey, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Ansley J Kunnath
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - Linda M Brzustowicz
- Department of Genetics, Rutgers, The State University of New Jersey, 145 Bevier Road, Piscataway, NJ 08854, USA
| | - Steven M Silverstein
- Division of Schizophrenia Research, Rutgers University Behavioral Health Care, 671 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA.
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Guerra G, Lucariello A, Perna A, Botta L, De Luca A, Moccia F. The Role of Endothelial Ca 2+ Signaling in Neurovascular Coupling: A View from the Lumen. Int J Mol Sci 2018; 19:E938. [PMID: 29561829 PMCID: PMC5979341 DOI: 10.3390/ijms19040938] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+-dependent manner throughout peripheral vasculature. METHODS We analyzed the literature in search of the most recent updates on the potential role of endothelial Ca2+ signaling in NVC. RESULTS We found that several neurotransmitters (i.e., glutamate and acetylcholine) and neuromodulators (e.g., ATP) can induce dilation of cerebral vessels by inducing an increase in endothelial Ca2+ concentration. This, in turn, results in nitric oxide or prostaglandin E2 release or activate intermediate and small-conductance Ca2+-activated K⁺ channels, which are responsible for endothelial-dependent hyperpolarization (EDH). In addition, brain endothelial cells express multiple transient receptor potential (TRP) channels (i.e., TRPC3, TRPV3, TRPV4, TRPA1), which induce vasodilation by activating EDH. CONCLUSIONS It is possible to conclude that endothelial Ca2+ signaling is an emerging pathway in the control of NVC.
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Affiliation(s)
- Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Angela Lucariello
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
| | - Antonio De Luca
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
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Endothelial Ca 2+ Signaling and the Resistance to Anticancer Treatments: Partners in Crime. Int J Mol Sci 2018; 19:ijms19010217. [PMID: 29324706 PMCID: PMC5796166 DOI: 10.3390/ijms19010217] [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: 12/06/2017] [Revised: 01/08/2018] [Accepted: 01/10/2018] [Indexed: 02/06/2023] Open
Abstract
Intracellular Ca2+ signaling drives angiogenesis and vasculogenesis by stimulating proliferation, migration, and tube formation in both vascular endothelial cells and endothelial colony forming cells (ECFCs), which represent the only endothelial precursor truly belonging to the endothelial phenotype. In addition, local Ca2+ signals at the endoplasmic reticulum (ER)-mitochondria interface regulate endothelial cell fate by stimulating survival or apoptosis depending on the extent of the mitochondrial Ca2+ increase. The present article aims at describing how remodeling of the endothelial Ca2+ toolkit contributes to establish intrinsic or acquired resistance to standard anti-cancer therapies. The endothelial Ca2+ toolkit undergoes a major alteration in tumor endothelial cells and tumor-associated ECFCs. These include changes in TRPV4 expression and increase in the expression of P2X7 receptors, Piezo2, Stim1, Orai1, TRPC1, TRPC5, Connexin 40 and dysregulation of the ER Ca2+ handling machinery. Additionally, remodeling of the endothelial Ca2+ toolkit could involve nicotinic acetylcholine receptors, gasotransmitters-gated channels, two-pore channels and Na⁺/H⁺ exchanger. Targeting the endothelial Ca2+ toolkit could represent an alternative adjuvant therapy to circumvent patients' resistance to current anti-cancer treatments.
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Tarantini S, Yabluchanksiy A, Fülöp GA, Hertelendy P, Valcarcel-Ares MN, Kiss T, Bagwell JM, O'Connor D, Farkas E, Sorond F, Csiszar A, Ungvari Z. Pharmacologically induced impairment of neurovascular coupling responses alters gait coordination in mice. GeroScience 2017; 39:601-614. [PMID: 29243191 PMCID: PMC5745218 DOI: 10.1007/s11357-017-0003-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/01/2017] [Indexed: 12/20/2022] Open
Abstract
There is correlative evidence that impaired cerebral blood flow (CBF) regulation, in addition to promoting cognitive impairment, is also associated with alterations in gait and development of falls in elderly people. CBF is adjusted to neuronal activity via neurovascular coupling (NVC) and this mechanism becomes progressively impaired with age. To establish a direct cause-and-effect relationship between impaired NVC and gait abnormalities, we induced neurovascular uncoupling pharmacologically in young C57BL/6 mice by inhibiting the synthesis of vasodilator mediators involved in NVC. Treatment of mice with the epoxygenase inhibitor MSPPOH, the NO synthase inhibitor L-NAME, and the COX inhibitor indomethacin significantly decreased NVC mimicking the aging phenotype. Pharmacologically induced neurovascular uncoupling significantly decreased the dynamic gait parameter duty cycle, altered footfall patterns, and significantly increased phase dispersion, indicating impaired interlimb coordination. Impaired NVC also tended to increase gait variability. Thus, selective experimental disruption of NVC causes subclinical gait abnormalities, supporting the importance of CBF in both cognitive function and gait regulation.
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Affiliation(s)
- Stefano Tarantini
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Andriy Yabluchanksiy
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Gábor A Fülöp
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Hertelendy
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - M Noa Valcarcel-Ares
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Tamas Kiss
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jonathan M Bagwell
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, USA
| | - Daniel O'Connor
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Eszter Farkas
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Farzaneh Sorond
- Department of Neurology, Northwestern University, Chicago, IL, USA
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
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Jiang H, Wu M, Liu Y, Song L, Li S, Wang X, Zhang YF, Fang J, Wu S. Serine racemase deficiency attenuates choroidal neovascularization and reduces nitric oxide and VEGF levels by retinal pigment epithelial cells. J Neurochem 2017; 143:375-388. [PMID: 28892569 DOI: 10.1111/jnc.14214] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/16/2017] [Accepted: 09/05/2017] [Indexed: 02/01/2023]
Abstract
Choroidal neovascularization (CNV) is a leading cause of blindness in age-related macular degeneration. Production of vascular endothelial growth factor (VEGF) and macrophage recruitment by retinal pigment epithelial cells (RPE) significantly contributes to the process of CNV in an experimental CNV model. Serine racemase (SR) is expressed in retinal neurons and glial cells, and its product, d-serine, is an endogenous co-agonist of N-methyl-d-aspartate receptor. Activation of the receptor results in production of nitric oxide (. NO), a molecule that promotes retinal and choroidal neovascularization. These observations suggest possible roles of SR in CNV. With laser-injured CNV mice, we found that inactivation of SR-coding gene (Srrnull ) significantly reduced CNV volume, neovascular density, and invading macrophages. We exploited the underlying mechanism in vivo and ex vivo. RPE from wild-type (WT) mice expressed SR. To explore the possible downstream target of SR inactivation, we showed that choroid/RPE homogenates extracted from laser-injured Srrnull mice contained less inducible nitric oxide synthase and decreased phospho-VEGFR2 compared to amounts in WT mice. In vitro, inflammation-primed WT RPEs expressed more inducible NOS, produced more. NO and VEGF than did inflammation-primed Srrnull RPEs. When co-cultured with inflammation-primed Srrnull RPE, significantly fewer RF/6A-a cell line of choroidal endothelial cell, migrated to the opposite side of the insert membrane than did cells co-cultured with pre-treated WT RPE. Altogether, SR deficiency reduces RPE response to laser-induced inflammatory stimuli, resulting in decreased production of a cascade of pro-angiogenic cytokines, including. NO and VEGF, and reduced macrophage recruitment, which contribute synergistically to attenuated angiogenesis.
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Affiliation(s)
- Haiyan Jiang
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Mengjuan Wu
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Yimei Liu
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Liping Song
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Shifeng Li
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xianwei Wang
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Yun-Feng Zhang
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Junxu Fang
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
| | - Shengzhou Wu
- School of Optometry and Ophthalmolgy and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Visual Science, Wenzhou, Zhejiang, China
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The Neurovascular Unit Coming of Age: A Journey through Neurovascular Coupling in Health and Disease. Neuron 2017; 96:17-42. [PMID: 28957666 DOI: 10.1016/j.neuron.2017.07.030] [Citation(s) in RCA: 1303] [Impact Index Per Article: 186.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/20/2017] [Accepted: 07/25/2017] [Indexed: 02/07/2023]
Abstract
The concept of the neurovascular unit (NVU), formalized at the 2001 Stroke Progress Review Group meeting of the National Institute of Neurological Disorders and Stroke, emphasizes the intimate relationship between the brain and its vessels. Since then, the NVU has attracted the interest of the neuroscience community, resulting in considerable advances in the field. Here the current state of knowledge of the NVU will be assessed, focusing on one of its most vital roles: the coupling between neural activity and blood flow. The evidence supports a conceptual shift in the mechanisms of neurovascular coupling, from a unidimensional process involving neuronal-astrocytic signaling to local blood vessels to a multidimensional one in which mediators released from multiple cells engage distinct signaling pathways and effector systems across the entire cerebrovascular network in a highly orchestrated manner. The recently appreciated NVU dysfunction in neurodegenerative diseases, although still poorly understood, supports emerging concepts that maintaining neurovascular health promotes brain health.
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Csiszar A, Tarantini S, Fülöp GA, Kiss T, Valcarcel-Ares MN, Galvan V, Ungvari Z, Yabluchanskiy A. Hypertension impairs neurovascular coupling and promotes microvascular injury: role in exacerbation of Alzheimer's disease. GeroScience 2017; 39:359-372. [PMID: 28853030 PMCID: PMC5636770 DOI: 10.1007/s11357-017-9991-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/26/2017] [Indexed: 12/13/2022] Open
Abstract
Hypertension in the elderly substantially increases both the risk of vascular cognitive impairment (VCI) and Alzheimer's disease (AD); however, the underlying mechanisms are not completely understood. This review discusses the effects of hypertension on structural and functional integrity of cerebral microcirculation, including hypertension-induced alterations in neurovascular coupling responses, cellular and molecular mechanisms involved in microvascular damage (capillary rarefaction, blood-brain barrier disruption), and the genesis of cerebral microhemorrhages and their potential role in exacerbation of cognitive decline associated with AD. Understanding and targeting the hypertension-induced cerebromicrovascular alterations that are involved in the onset and progression of AD and contribute to cognitive impairment are expected to have a major role in preserving brain health in high-risk older individuals.
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Affiliation(s)
- Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Stefano Tarantini
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Gábor A Fülöp
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamas Kiss
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - M Noa Valcarcel-Ares
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Veronica Galvan
- Department of Cellular and Integrative Physiology, Barshop Institute for Longevity and Aging Studies University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Andriy Yabluchanskiy
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Tarantini S, Fulop GA, Kiss T, Farkas E, Zölei-Szénási D, Galvan V, Toth P, Csiszar A, Ungvari Z, Yabluchanskiy A. Demonstration of impaired neurovascular coupling responses in TG2576 mouse model of Alzheimer's disease using functional laser speckle contrast imaging. GeroScience 2017; 39:465-473. [PMID: 28578467 PMCID: PMC5636768 DOI: 10.1007/s11357-017-9980-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 05/23/2017] [Indexed: 01/28/2023] Open
Abstract
Increasing evidence from epidemiological, clinical, and experimental studies indicates that cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including both vascular cognitive impairment (VCI) and Alzheimer's disease. Vascular contributions to cognitive impairment and dementia (VCID) include impairment of neurovascular coupling responses/functional hyperemia ("neurovascular uncoupling"). Due to the growing interest in understanding and pharmacologically targeting pathophysiological mechanisms of VCID, there is an increasing need for sensitive, easy-to-establish methods to assess neurovascular coupling responses. Laser speckle contrast imaging (LSCI) is a technique that allows rapid and minimally invasive visualization of changes in regional cerebromicrovascular blood perfusion. This type of imaging technique combines high resolution and speed to provide great spatiotemporal accuracy to measure moment-to-moment changes in cerebral blood flow induced by neuronal activation. Here, we provide detailed protocols for the successful measurement in neurovascular coupling responses in anesthetized mice equipped with a thinned-skull cranial window using LSCI. This method can be used to evaluate the effects of anti-aging or anti-AD treatments on cerebromicrovascular health.
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Affiliation(s)
- Stefano Tarantini
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
| | - Gabor A Fulop
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
| | - Tamas Kiss
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
- Faculty of Medicine & Faculty of Science and Informatics, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Eszter Farkas
- Faculty of Medicine & Faculty of Science and Informatics, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Dániel Zölei-Szénási
- Faculty of Medicine & Faculty of Science and Informatics, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Veronica Galvan
- Department of Cellular and Integrative Physiology, Barshop Institute for Longevity and Aging Studies University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Peter Toth
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA
| | - Andriy Yabluchanskiy
- Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma, OK, 73104, USA.
- Translational Geroscience Laboratory, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK, USA.
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Steady-State Free Ca 2+ in Astrocytes Is Decreased by Experience and Impacts Arteriole Tone. J Neurosci 2017; 37:8150-8165. [PMID: 28733356 DOI: 10.1523/jneurosci.0239-17.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 06/23/2017] [Accepted: 07/10/2017] [Indexed: 12/27/2022] Open
Abstract
Astrocytes can control basal synaptic strength and arteriole tone via their resting Ca2+ activity. However, whether resting astrocyte Ca2+ can adjust to a new steady-state level, with an impact on surrounding brain cells, remains unknown. Using two-photon Ca2+ imaging in male rat acute brain slices of the somatosensory neocortex, we found that theta burst neural activity produced an unexpected long-lasting reduction in astrocyte free Ca2+ in the soma and endfeet. The drop in intracellular Ca2+ was attenuated by antagonists targeting multiple ionotropic and metabotropic glutamate receptors, and intracellular cascades involved Ca2+ stores and nitric oxide. The reduction in astrocyte endfoot Ca2+ was coincident with an increase in arteriole tone, and both the Ca2+ drop and the tone change were prevented by an NMDA receptor antagonist. Astrocyte patch-clamp experiments verified that the glutamate receptors in question were located on astrocytes and that Ca2+ changes within astrocytes were responsible for the long-lasting change in arteriole diameter caused by theta burst neural activity. In astrocytes from animals that lived in an enriched environment, we measured a relatively lower resting Ca2+ level that occluded any further drop in Ca2+ in response to theta burst activity. These data suggest that electrically evoked patterns of neural activity or natural experience can adjust steady-state resting astrocyte Ca2+ and that the effect has an impact on basal arteriole diameter.SIGNIFICANCE STATEMENT The field of astrocyte-neuron and astrocyte-arteriole interactions is currently in a state of refinement. Experimental evidence ex vivo suggests that direct manipulation of astrocyte-free Ca2+ regulates synaptic signaling and local blood flow control; however, in vivo experiments fail to link synaptically evoked astrocyte Ca2+ transients and immediate changes to various astrocyte-mediated processes. To clarify this discrepancy, we examined a different aspect of astrocyte Ca2+: the resting, steady-state free Ca2+ of astrocytes, its modulation, and its potential role in the tonic regulation of surrounding brain cells. We found that ex vivo or in vivo neural activity induced a long-lasting reduction in resting free astrocyte Ca2+ and that this phenomenon changed arteriole tone.
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Sifuentes MM, Lechleiter JD. Thyroid Hormone Stimulation of Adult Brain Fatty Acid Oxidation. VITAMINS AND HORMONES 2017; 106:163-193. [PMID: 29407434 DOI: 10.1016/bs.vh.2017.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Thyroid hormone is a critical modulator of brain metabolism, and it is highly controlled in the central nervous system. Recent research has uncovered an important role of thyroid hormone in the regulation of fatty acid oxidation (FAO), an energetic process essential for neurodevelopment that continues to support brain metabolism during adulthood. Thyroid hormone stimulation of FAO has been shown to be protective in astrocytes and mouse models of brain injury, yet a clear mechanism of this relationship has not been elucidated. Thyroid hormone interacts with multiple receptors located in the nucleus and the mitochondria, initiating rapid and long-term effects via both genomic and nongenomic pathways. This has complicated efforts to isolate and study-specific interactions. This chapter presents the primary signaling pathways that have been identified to play a role in the thyroid hormone-mediated increase in FAO. Investigation of the impact of thyroid hormone on FAO in the adult brain has challenged classical models of brain metabolism and widened the window of potential neuroprotective strategies. A detailed understanding of these pathways is essential for any researchers aiming to expand the field of neuroenergetics.
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San Martín A, Arce-Molina R, Galaz A, Pérez-Guerra G, Barros LF. Nanomolar nitric oxide concentrations quickly and reversibly modulate astrocytic energy metabolism. J Biol Chem 2017; 292:9432-9438. [PMID: 28341740 PMCID: PMC5454122 DOI: 10.1074/jbc.m117.777243] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/14/2017] [Indexed: 01/04/2023] Open
Abstract
Nitric oxide (NO) is an intercellular messenger involved in multiple bodily functions. Prolonged NO exposure irreversibly inhibits respiration by covalent modification of mitochondrial cytochrome oxidase, a phenomenon of pathological relevance. However, the speed and potency of NO's metabolic effects at physiological concentrations are incompletely characterized. To this end, we set out to investigate the metabolic effects of NO in cultured astrocytes from mice by taking advantage of the high spatiotemporal resolution afforded by genetically encoded Förster resonance energy transfer (FRET) nanosensors. NO exposure resulted in immediate and reversible intracellular glucose depletion and lactate accumulation. Consistent with cytochrome oxidase involvement, the glycolytic effect was enhanced at a low oxygen level and became irreversible at a high NO concentration or after prolonged exposure. Measurements of both glycolytic rate and mitochondrial pyruvate consumption revealed significant effects even at nanomolar NO concentrations. We conclude that NO can modulate astrocytic energy metabolism in the short term, reversibly, and at concentrations known to be released by endothelial cells under physiological conditions. These findings suggest that NO modulates the size of the astrocytic lactate reservoir involved in neuronal fueling and signaling.
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Affiliation(s)
- Alejandro San Martín
- From the Centro de Estudios Científicos (CECs), 5110466 Valdivia and
- the Universidad Austral de Chile, 5110566 Valdivia, Chile
| | - Robinson Arce-Molina
- From the Centro de Estudios Científicos (CECs), 5110466 Valdivia and
- the Universidad Austral de Chile, 5110566 Valdivia, Chile
| | - Alex Galaz
- From the Centro de Estudios Científicos (CECs), 5110466 Valdivia and
| | - Gustavo Pérez-Guerra
- From the Centro de Estudios Científicos (CECs), 5110466 Valdivia and
- the Universidad Austral de Chile, 5110566 Valdivia, Chile
| | - L Felipe Barros
- From the Centro de Estudios Científicos (CECs), 5110466 Valdivia and
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Acosta C, Anderson HD, Anderson CM. Astrocyte dysfunction in Alzheimer disease. J Neurosci Res 2017; 95:2430-2447. [PMID: 28467650 DOI: 10.1002/jnr.24075] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022]
Abstract
Astrocytes are glial cells that are distributed throughout the central nervous system in an arrangement optimal for chemical and physical interaction with neuronal synapses and brain blood supply vessels. Neurotransmission modulates astrocytic excitability by activating an array of cell surface receptors and transporter proteins, resulting in dynamic changes in intracellular Ca2+ or Na+ . Ionic and electrogenic astrocytic changes, in turn, drive vital cell nonautonomous effects supporting brain function, including regulation of synaptic activity, neuronal metabolism, and regional blood supply. Alzheimer disease (AD) is associated with aberrant oligomeric amyloid β generation, which leads to extensive proliferation of astrocytes with a reactive phenotype and abnormal regulation of these processes. Astrocytic morphology, Ca2+ responses, extracellular K+ removal, glutamate transport, amyloid clearance, and energy metabolism are all affected in AD, resulting in a deleterious set of effects that includes glutamate excitotoxicity, impaired synaptic plasticity, reduced carbon delivery to neurons for oxidative phosphorylation, and dysregulated linkages between neuronal energy demand and regional blood supply. This review summarizes how astrocytes are affected in AD and describes how these changes are likely to influence brain function. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Crystal Acosta
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada
| | - Hope D Anderson
- Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada.,College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Christopher M Anderson
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba, Canada
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Ungvari Z, Tarantini S, Hertelendy P, Valcarcel-Ares MN, Fülöp GA, Logan S, Kiss T, Farkas E, Csiszar A, Yabluchanskiy A. Cerebromicrovascular dysfunction predicts cognitive decline and gait abnormalities in a mouse model of whole brain irradiation-induced accelerated brain senescence. GeroScience 2017; 39:33-42. [PMID: 28299642 DOI: 10.1007/s11357-017-9964-z] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 01/25/2017] [Indexed: 01/02/2023] Open
Abstract
Whole brain irradiation (WBI) is a mainstream therapy for patients with both identifiable brain metastases and prophylaxis for microscopic malignancies. However, it also promotes accelerated senescence in healthy tissues and leads to progressive cognitive dysfunction in up to 50% of tumor patients surviving long term after treatment, due to γ-irradiation-induced cerebromicrovascular injury. Moment-to-moment adjustment of cerebral blood flow (CBF) via neuronal activity-dependent cerebromicrovascular dilation (functional hyperemia) has a critical role in maintenance of healthy cognitive function. To determine whether cognitive decline induced by WBI associates with impaired cerebromicrovascular function, C56BL/6 mice (3 months) subjected to a clinically relevant protocol of fractionated WBI (5 Gy twice weekly for 4 weeks) and control mice were compared. Mice were tested for spatial memory performance (radial arm water maze), sensorimotor coordination (computerized gait analysis, CatWalk), and cerebromicrovascular function (whisker-stimulation-induced increases in CBF, measured by laser Doppler flowmetry) at 3 to 6 months post-irradiation. We found that mice with WBI exhibited impaired cerebromicrovascular function at 3 months post-irradiation, which was associated with impaired performance in the radial arm water maze. At 6 months, post-irradiation progressive impairment in gait coordination (including changes in the regularity index and phase dispersion) was also evident. Collectively, our findings provide evidence for early and persisting neurovascular impairment after a clinically relevant protocol of fractionated WBI, which predict early manifestations of cognitive impairment.
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Affiliation(s)
- Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Stefano Tarantini
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Peter Hertelendy
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - M Noa Valcarcel-Ares
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Gabor A Fülöp
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Sreemathi Logan
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Tamas Kiss
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Eszter Farkas
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Andriy Yabluchanskiy
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.
- Translational Geroscience Laboratory, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Toth P, Tarantini S, Csiszar A, Ungvari Z. Functional vascular contributions to cognitive impairment and dementia: mechanisms and consequences of cerebral autoregulatory dysfunction, endothelial impairment, and neurovascular uncoupling in aging. Am J Physiol Heart Circ Physiol 2017; 312:H1-H20. [PMID: 27793855 PMCID: PMC5283909 DOI: 10.1152/ajpheart.00581.2016] [Citation(s) in RCA: 324] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/10/2016] [Accepted: 10/26/2016] [Indexed: 12/16/2022]
Abstract
Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) are expected to have a major role in preserving brain health in older individuals. Maintenance of cerebral perfusion, protecting the microcirculation from high pressure-induced damage and moment-to-moment adjustment of regional oxygen and nutrient supply to changes in demand are prerequisites for the prevention of cerebral ischemia and neuronal dysfunction. This overview discusses age-related alterations in three main regulatory paradigms involved in the regulation of cerebral blood flow (CBF): cerebral autoregulation/myogenic constriction, endothelium-dependent vasomotor function, and neurovascular coupling responses responsible for functional hyperemia. The pathophysiological consequences of cerebral microvascular dysregulation in aging are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages, microvascular rarefaction, and ischemic neuronal dysfunction and damage. Due to the widespread attention that VCID has captured in recent years, the evidence for the causal role of cerebral microvascular dysregulation in cognitive decline is critically examined.
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Affiliation(s)
- Peter Toth
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Department of Neurosurgery and Szentagothai Research Center, University of Pecs, Pecs, Hungary; and
| | - Stefano Tarantini
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Anna Csiszar
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Zoltan Ungvari
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma;
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
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Mishra A, Reynolds JP, Chen Y, Gourine AV, Rusakov DA, Attwell D. Astrocytes mediate neurovascular signaling to capillary pericytes but not to arterioles. Nat Neurosci 2016; 19:1619-1627. [PMID: 27775719 PMCID: PMC5131849 DOI: 10.1038/nn.4428] [Citation(s) in RCA: 365] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/20/2016] [Indexed: 12/11/2022]
Abstract
Active neurons increase their energy supply by dilating nearby arterioles and capillaries. This neurovascular coupling underlies blood oxygen level-dependent functional imaging signals, but its mechanism is controversial. Canonically, neurons release glutamate to activate metabotropic glutamate receptor 5 (mGluR5) on astrocytes, evoking Ca2+ release from internal stores, activating phospholipase A2 and generating vasodilatory arachidonic acid derivatives. However, adult astrocytes lack mGluR5, and knockout of the inositol 1,4,5-trisphosphate receptors that release Ca2+ from stores does not affect neurovascular coupling. We now show that buffering astrocyte Ca2+ inhibits neuronally evoked capillary dilation, that astrocyte [Ca2+]i is raised not by release from stores but by entry through ATP-gated channels, and that Ca2+ generates arachidonic acid via phospholipase D2 and diacylglycerol lipase rather than phospholipase A2. In contrast, dilation of arterioles depends on NMDA receptor activation and Ca2+-dependent NO generation by interneurons. These results reveal that different signaling cascades regulate cerebral blood flow at the capillary and arteriole levels.
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Affiliation(s)
- Anusha Mishra
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | | | - Yang Chen
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | - Alexander V Gourine
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | | | - David Attwell
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
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Tarantini S, Tran CHT, Gordon GR, Ungvari Z, Csiszar A. Impaired neurovascular coupling in aging and Alzheimer's disease: Contribution of astrocyte dysfunction and endothelial impairment to cognitive decline. Exp Gerontol 2016; 94:52-58. [PMID: 27845201 DOI: 10.1016/j.exger.2016.11.004] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/02/2016] [Accepted: 11/10/2016] [Indexed: 12/11/2022]
Abstract
The importance of (micro)vascular contributions to cognitive impairment and dementia (VCID) in aging cannot be overemphasized, and the pathogenesis and prevention of age-related cerebromicrovascular pathologies are a subject of intensive research. In particular, aging impairs the increase in cerebral blood flow triggered by neural activation (termed neurovascular coupling or functional hyperemia), a critical mechanism that matches oxygen and nutrient delivery with the increased demands in active brain regions. From epidemiological, clinical and experimental studies the picture emerges of a complex functional impairment of cerebral microvessels and astrocytes, which likely contribute to neurovascular dysfunction and cognitive decline in aging and in age-related neurodegenerative diseases. This overview discusses age-related alterations in neurovascular coupling responses responsible for impaired functional hyperemia. The mechanisms and consequences of astrocyte dysfunction (including potential alteration of astrocytic endfeet calcium signaling, dysregulation of eicosanoid gliotransmitters and astrocyte energetics) and functional impairment of the microvascular endothelium are explored. Age-related mechanisms (cellular oxidative stress, senescence, circulating IGF-1 deficiency) impairing the function of cells of the neurovascular unit are discussed and the evidence for the causal role of neurovascular uncoupling in cognitive decline is critically examined.
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Affiliation(s)
- Stefano Tarantini
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Cam Ha T Tran
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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69
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Lecrux C, Hamel E. Neuronal networks and mediators of cortical neurovascular coupling responses in normal and altered brain states. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150350. [PMID: 27574304 PMCID: PMC5003852 DOI: 10.1098/rstb.2015.0350] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 12/18/2022] Open
Abstract
Brain imaging techniques that use vascular signals to map changes in neuronal activity, such as blood oxygenation level-dependent functional magnetic resonance imaging, rely on the spatial and temporal coupling between changes in neurophysiology and haemodynamics, known as 'neurovascular coupling (NVC)'. Accordingly, NVC responses, mapped by changes in brain haemodynamics, have been validated for different stimuli under physiological conditions. In the cerebral cortex, the networks of excitatory pyramidal cells and inhibitory interneurons generating the changes in neural activity and the key mediators that signal to the vascular unit have been identified for some incoming afferent pathways. The neural circuits recruited by whisker glutamatergic-, basal forebrain cholinergic- or locus coeruleus noradrenergic pathway stimulation were found to be highly specific and discriminative, particularly when comparing the two modulatory systems to the sensory response. However, it is largely unknown whether or not NVC is still reliable when brain states are altered or in disease conditions. This lack of knowledge is surprising since brain imaging is broadly used in humans and, ultimately, in conditions that deviate from baseline brain function. Using the whisker-to-barrel pathway as a model of NVC, we can interrogate the reliability of NVC under enhanced cholinergic or noradrenergic modulation of cortical circuits that alters brain states.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- C Lecrux
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Quebec, Canada H3A 2B4
| | - E Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Quebec, Canada H3A 2B4
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Physiological Roles of Non-Neuronal NMDA Receptors. Trends Pharmacol Sci 2016; 37:750-767. [DOI: 10.1016/j.tips.2016.05.012] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/23/2016] [Accepted: 05/27/2016] [Indexed: 12/14/2022]
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Longden TA, Hill-Eubanks DC, Nelson MT. Ion channel networks in the control of cerebral blood flow. J Cereb Blood Flow Metab 2016; 36:492-512. [PMID: 26661232 PMCID: PMC4794103 DOI: 10.1177/0271678x15616138] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/17/2015] [Accepted: 10/14/2015] [Indexed: 12/26/2022]
Abstract
One hundred and twenty five years ago, Roy and Sherrington made the seminal observation that neuronal stimulation evokes an increase in cerebral blood flow.(1) Since this discovery, researchers have attempted to uncover how the cells of the neurovascular unit-neurons, astrocytes, vascular smooth muscle cells, vascular endothelial cells and pericytes-coordinate their activity to control this phenomenon. Recent work has revealed that ionic fluxes through a diverse array of ion channel species allow the cells of the neurovascular unit to engage in multicellular signaling processes that dictate local hemodynamics.In this review we center our discussion on two major themes: (1) the roles of ion channels in the dynamic modulation of parenchymal arteriole smooth muscle membrane potential, which is central to the control of arteriolar diameter and therefore must be harnessed to permit changes in downstream cerebral blood flow, and (2) the striking similarities in the ion channel complements employed in astrocytic endfeet and endothelial cells, enabling dual control of smooth muscle from either side of the blood-brain barrier. We conclude with a discussion of the emerging roles of pericyte and capillary endothelial cell ion channels in neurovascular coupling, which will provide fertile ground for future breakthroughs in the field.
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Affiliation(s)
- Thomas A Longden
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | | | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
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Toth P, Tarantini S, Ashpole NM, Tucsek Z, Milne GL, Valcarcel‐Ares NM, Menyhart A, Farkas E, Sonntag WE, Csiszar A, Ungvari Z. IGF-1 deficiency impairs neurovascular coupling in mice: implications for cerebromicrovascular aging. Aging Cell 2015; 14:1034-44. [PMID: 26172407 PMCID: PMC4693458 DOI: 10.1111/acel.12372] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2015] [Indexed: 12/24/2022] Open
Abstract
Aging is associated with marked deficiency in circulating IGF‐1, which has been shown to contribute to age‐related cognitive decline. Impairment of moment‐to‐moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of age‐related cognitive impairment. To establish the link between IGF‐1 deficiency and cerebromicrovascular impairment, neurovascular coupling mechanisms were studied in a novel mouse model of IGF‐1 deficiency (Igf1f/f‐TBG‐Cre‐AAV8) and accelerated vascular aging. We found that IGF‐1‐deficient mice exhibit neurovascular uncoupling and show a deficit in hippocampal‐dependent spatial memory test, mimicking the aging phenotype. IGF‐1 deficiency significantly impaired cerebromicrovascular endothelial function decreasing NO mediation of neurovascular coupling. IGF‐1 deficiency also impaired glutamate‐mediated CBF responses, likely due to dysregulation of astrocytic expression of metabotropic glutamate receptors and impairing mediation of CBF responses by eicosanoid gliotransmitters. Collectively, we demonstrate that IGF‐1 deficiency promotes cerebromicrovascular dysfunction and neurovascular uncoupling mimicking the aging phenotype, which are likely to contribute to cognitive impairment.
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Affiliation(s)
- Peter Toth
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
| | - Stefano Tarantini
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
| | - Nicole M. Ashpole
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Zsuzsanna Tucsek
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Ginger L. Milne
- Division of Clinical Pharmacology Vanderbilt University Medical Center D‐3100 Medical Center North Nashville TN USA
| | - Noa M. Valcarcel‐Ares
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Akos Menyhart
- Department of Medical Physics and Informatics Faculty of Medicine and Faculty of Science and Informatics University of Szeged Szeged 6720Hungary
| | - Eszter Farkas
- Department of Medical Physics and Informatics Faculty of Medicine and Faculty of Science and Informatics University of Szeged Szeged 6720Hungary
| | - William E. Sonntag
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Anna Csiszar
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Zoltan Ungvari
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Pulmonology 1125 Budapest, Diós árok 1/c Semmelweis University Budapest Hungary
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Galvan V, Hart MJ. Vascular mTOR-dependent mechanisms linking the control of aging to Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2015; 1862:992-1007. [PMID: 26639036 DOI: 10.1016/j.bbadis.2015.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 02/07/2023]
Abstract
Aging is the strongest known risk factor for Alzheimer's disease (AD). With the discovery of the mechanistic target of rapamycin (mTOR) as a critical pathway controlling the rate of aging in mice, molecules at the interface between the regulation of aging and the mechanisms of specific age-associated diseases can be identified. We will review emerging evidence that mTOR-dependent brain vascular dysfunction, a universal feature of aging, may be one of the mechanisms linking the regulation of the rate of aging to the pathogenesis of Alzheimer's disease. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.
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Affiliation(s)
- Veronica Galvan
- Department of Physiology and the Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio.
| | - Matthew J Hart
- Department of Biochemistry, University of Texas Health Science Center at San Antonio
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Pharmacologically-induced neurovascular uncoupling is associated with cognitive impairment in mice. J Cereb Blood Flow Metab 2015; 35:1871-81. [PMID: 26174328 PMCID: PMC4635246 DOI: 10.1038/jcbfm.2015.162] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 05/23/2015] [Accepted: 05/29/2015] [Indexed: 01/15/2023]
Abstract
There is increasing evidence that vascular risk factors, including aging, hypertension, diabetes mellitus, and obesity, promote cognitive impairment; however, the underlying mechanisms remain obscure. Cerebral blood flow (CBF) is adjusted to neuronal activity via neurovascular coupling (NVC) and this mechanism is known to be impaired in the aforementioned pathophysiologic conditions. To establish a direct relationship between impaired NVC and cognitive decline, we induced neurovascular uncoupling pharmacologically in mice by inhibiting the synthesis of vasodilator mediators involved in NVC. Treatment of mice with the epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MSPPOH), the NO synthase inhibitor l-NG-Nitroarginine methyl ester (L-NAME), and the COX inhibitor indomethacin decreased NVC by over 60% mimicking the aging phenotype, which was associated with significantly impaired spatial working memory (Y-maze), recognition memory (Novel object recognition), and impairment in motor coordination (Rotarod). Blood pressure (tail cuff) and basal cerebral perfusion (arterial spin labeling perfusion MRI) were unaffected. Thus, selective experimental disruption of NVC is associated with significant impairment of cognitive and sensorimotor function, recapitulating neurologic symptoms and signs observed in brain aging and pathophysiologic conditions associated with accelerated cerebromicrovascular aging.
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Toth P, Tarantini S, Davila A, Valcarcel-Ares MN, Tucsek Z, Varamini B, Ballabh P, Sonntag WE, Baur JA, Csiszar A, Ungvari Z. Purinergic glio-endothelial coupling during neuronal activity: role of P2Y1 receptors and eNOS in functional hyperemia in the mouse somatosensory cortex. Am J Physiol Heart Circ Physiol 2015; 309:H1837-45. [PMID: 26453330 DOI: 10.1152/ajpheart.00463.2015] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/25/2015] [Indexed: 12/22/2022]
Abstract
Impairment of moment-to-moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of cognitive impairment associated with aging and pathological conditions associated with accelerated cerebromicrovascular aging (e.g., hypertension, obesity). Although previous studies demonstrate that endothelial dysfunction plays a critical role in neurovascular uncoupling in these conditions, the role of endothelial NO mediation in neurovascular coupling responses is not well understood. To establish the link between endothelial function and functional hyperemia, neurovascular coupling responses were studied in mutant mice overexpressing or deficient in endothelial NO synthase (eNOS), and the role of P2Y1 receptors in purinergic glioendothelial coupling was assessed. We found that genetic depletion of eNOS (eNOS(-/-)) and pharmacological inhibition of NO synthesis significantly decreased the CBF responses in the somatosensory cortex evoked by whisker stimulation and by administration of ATP. Overexpression of eNOS enhanced NO mediation of functional hyperemia. In control mice, the selective and potent P2Y1 receptor antagonist MRS2179 attenuated both whisker stimulation-induced and ATP-mediated CBF responses, whereas, in eNOS(-/-) mice, the inhibitory effects of MRS2179 were blunted. Collectively, our findings provide additional evidence for purinergic glio-endothelial coupling during neuronal activity, highlighting the role of ATP-mediated activation of eNOS via P2Y1 receptors in functional hyperemia.
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Affiliation(s)
- Peter Toth
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Department of Neurosurgery, University of Pecs, Pecs, Hungary; Szentagothai Research Center, Medical School, University of Pecs, Pecs, Hungary
| | - Stefano Tarantini
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Antonio Davila
- Institute for Diabetes, Obesity, and Metabolism and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - M Noa Valcarcel-Ares
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Zsuzsanna Tucsek
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Szentagothai Research Center, Medical School, University of Pecs, Pecs, Hungary
| | - Behzad Varamini
- Biological Sciences Department, Biola University, La Mirada, California
| | - Praveen Ballabh
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York; Department of Pediatrics, Regional Neonatal Center, Maria Fareri Children's Hospital at Westchester Medical Center, New York Medical College, Valhalla, New York
| | - William E Sonntag
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Joseph A Baur
- Institute for Diabetes, Obesity, and Metabolism and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Szentagothai Research Center, Medical School, University of Pecs, Pecs, Hungary; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Szentagothai Research Center, Medical School, University of Pecs, Pecs, Hungary; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Goveia J, Stapor P, Carmeliet P. Principles of targeting endothelial cell metabolism to treat angiogenesis and endothelial cell dysfunction in disease. EMBO Mol Med 2015; 6:1105-20. [PMID: 25063693 PMCID: PMC4197858 DOI: 10.15252/emmm.201404156] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The endothelium is the orchestral conductor of blood vessel function. Pathological blood vessel formation (a process termed pathological angiogenesis) or the inability of endothelial cells (ECs) to perform their physiological function (a condition known as EC dysfunction) are defining features of various diseases. Therapeutic intervention to inhibit aberrant angiogenesis or ameliorate EC dysfunction could be beneficial in diseases such as cancer and cardiovascular disease, respectively, but current strategies have limited efficacy. Based on recent findings that pathological angiogenesis and EC dysfunction are accompanied by EC-specific metabolic alterations, targeting EC metabolism is emerging as a novel therapeutic strategy. Here, we review recent progress in our understanding of how EC metabolism is altered in disease and discuss potential metabolic targets and strategies to reverse EC dysfunction and inhibit pathological angiogenesis.
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Affiliation(s)
- Jermaine Goveia
- Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven, Belgium Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center VIB, Leuven, Belgium
| | - Peter Stapor
- Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven, Belgium Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center VIB, Leuven, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven, Belgium Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center VIB, Leuven, Belgium
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Scherf T, Angenstein F. Postsynaptic and spiking activity of pyramidal cells, the principal neurons in the rat hippocampal CA1 region, does not control the resultant BOLD response: a combined electrophysiologic and fMRI approach. J Cereb Blood Flow Metab 2015; 35:565-75. [PMID: 25564229 PMCID: PMC4420892 DOI: 10.1038/jcbfm.2014.252] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 12/15/2014] [Indexed: 11/09/2022]
Abstract
The specific role of postsynaptic activity for the generation of a functional magnetic resonance imaging (fMRI) response was determined by a simultaneous measurement of generated field excitatory postsynaptic potentials (fEPSPs) and blood oxygen level-dependent (BOLD) response in the rat hippocampal CA1 region during electrical stimulation of the contralateral CA3 region. The stimulation electrode was placed either in the left CA3a/b or CA3c, causing the preferentially basal or apical dendrites of the pyramidal cells in the right CA1 to be activated. Consecutive stimulations with low-intensity stimulation trains (i.e., 16 pulses for 8 seconds) resulted in clear postsynaptic responses of CA1 pyramidal cells, but in no significant BOLD responses. In contrast, consecutive high-intensity stimulation trains resulted in stronger postsynaptic responses that came along with minor (during stimulation of the left CA3a/b) or substantial (during stimulation of the left CA3c) spiking activity of the CA1 pyramidal cells, and resulted in the generation of significant BOLD responses in the left and right hippocampus. Correlating the electrophysiologic parameters of CA1 pyramidal cell activity (fEPSP and spiking activity) with the resultant BOLD response revealed no positive correlation. Consequently, postsynaptic activity of pyramidal cells, the most abundant neurons in the CA1, is not directly linked to the measured BOLD response.
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Affiliation(s)
- Thomas Scherf
- Functional Neuroimaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Frank Angenstein
- 1] Functional Neuroimaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany [2] Special Lab for Noninvasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg, Germany
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78
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Pulgar VM. Direct electric stimulation to increase cerebrovascular function. Front Syst Neurosci 2015; 9:54. [PMID: 25870543 PMCID: PMC4378276 DOI: 10.3389/fnsys.2015.00054] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/13/2015] [Indexed: 12/23/2022] Open
Affiliation(s)
- Victor M Pulgar
- Biomedical Research and Infrastructure Center, Faculty of Natural and Physical Sciences, Winston-Salem State University Winston-Salem, NC, USA ; Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA ; Department of Obstetrics and Gynecology, Wake Forest School of Medicine Winston-Salem, NC, USA
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Muñoz MF, Puebla M, Figueroa XF. Control of the neurovascular coupling by nitric oxide-dependent regulation of astrocytic Ca(2+) signaling. Front Cell Neurosci 2015; 9:59. [PMID: 25805969 PMCID: PMC4354411 DOI: 10.3389/fncel.2015.00059] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/07/2015] [Indexed: 12/28/2022] Open
Abstract
Neuronal activity must be tightly coordinated with blood flow to keep proper brain function, which is achieved by a mechanism known as neurovascular coupling. Then, an increase in synaptic activity leads to a dilation of local parenchymal arterioles that matches the enhanced metabolic demand. Neurovascular coupling is orchestrated by astrocytes. These glial cells are located between neurons and the microvasculature, with the astrocytic endfeet ensheathing the vessels, which allows fine intercellular communication. The neurotransmitters released during neuronal activity reach astrocytic receptors and trigger a Ca2+ signaling that propagates to the endfeet, activating the release of vasoactive factors and arteriolar dilation. The astrocyte Ca2+ signaling is coordinated by gap junction channels and hemichannels formed by connexins (Cx43 and Cx30) and channels formed by pannexins (Panx-1). The neuronal activity-initiated Ca2+ waves are propagated among neighboring astrocytes directly via gap junctions or through ATP release via connexin hemichannels or pannexin channels. In addition, Ca2+ entry via connexin hemichannels or pannexin channels may participate in the regulation of the astrocyte signaling-mediated neurovascular coupling. Interestingly, nitric oxide (NO) can activate connexin hemichannel by S-nitrosylation and the Ca2+-dependent NO-synthesizing enzymes endothelial NO synthase (eNOS) and neuronal NOS (nNOS) are expressed in astrocytes. Therefore, the astrocytic Ca2+ signaling triggered in neurovascular coupling may activate NO production, which, in turn, may lead to Ca2+ influx through hemichannel activation. Furthermore, NO release from the hemichannels located at astrocytic endfeet may contribute to the vasodilation of parenchymal arterioles. In this review, we discuss the mechanisms involved in the regulation of the astrocytic Ca2+ signaling that mediates neurovascular coupling, with a special emphasis in the possible participation of NO in this process.
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Affiliation(s)
- Manuel F Muñoz
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mariela Puebla
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Xavier F Figueroa
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
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80
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Astrocytic Gq-GPCR-linked IP3R-dependent Ca2+ signaling does not mediate neurovascular coupling in mouse visual cortex in vivo. J Neurosci 2014; 34:13139-50. [PMID: 25253859 DOI: 10.1523/jneurosci.2591-14.2014] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Local blood flow is modulated in response to changing patterns of neuronal activity (Roy and Sherrington, 1890), a process termed neurovascular coupling. It has been proposed that the central cellular pathway driving this process is astrocytic Gq-GPCR-linked IP3R-dependent Ca(2+) signaling, though in vivo tests of this hypothesis are largely lacking. We examined the impact of astrocytic Gq-GPCR and IP3R-dependent Ca(2+) signaling on cortical blood flow in awake, lightly sedated, responsive mice using multiphoton laser-scanning microscopy and novel genetic tools that enable the selective manipulation of astrocytic signaling pathways in vivo. Selective stimulation of astrocytic Gq-GPCR cascades and downstream Ca(2+) signaling with the hM3Dq DREADD (designer receptors exclusively activated by designer drugs) designer receptor system was insufficient to modulate basal cortical blood flow. We found no evidence of observable astrocyte endfeet Ca(2+) elevations following physiological visual stimulation despite robust dilations of adjacent arterioles using cyto-GCaMP3 and Lck-GCaMP6s, the most sensitive Ca(2+) indicator available. Astrocytic Ca(2+) elevations could be evoked when inducing the startle response with unexpected air puffs. However, startle-induced astrocytic Ca(2+) signals did not precede corresponding startle-induced hemodynamic changes. Further, neurovascular coupling was intact in lightly sedated, responsive mice genetically lacking astrocytic IP3R-dependent Ca(2+) signaling (IP3R2 KO). These data demonstrate that astrocytic Gq-GPCR-linked IP3R-dependent Ca(2+) signaling does not mediate neurovascular coupling in visual cortex of awake, lightly sedated, responsive mice.
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Abstract
Astrocytes have been found to play important roles in physiology being fundamental for ionic homeostasis and glutamate clearance from the synaptic cleft by their plasma membrane glutamate transporters. Astrocytes are electrically non-excitable, but they exhibit Ca(2+) signaling, which now has been demonstrated to serve as an indirect mediator of neuron-glia bidirectional interactions through gliotransmission via tripartite synapses and to modulate synaptic function and plasticity. Spontaneous astrocytic Ca(2+) signaling was observed in vivo. Intercellular Ca(2+) waves in astrocytes can be evoked by a variety of stimulations. Astrocytes are critically involved in many pathological conditions including ischemic stroke. For example, it is well known that astrocytes become reactive and form glial scar after stroke. In animal models of some brain disorders, astrocytes have been shown to exhibit enhanced Ca(2+) excitability featured as regenerative intercellular Ca(2+) waves. This chapter briefly summarizes astrocytic Ca(2+) signaling pathways under normal conditions and in experimental in vitro and in vivo ischemic models. It discusses the possible mechanisms and therapeutic implication underlying the enhanced astrocytic Ca(2+) excitability in stroke.
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Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Bioengineering, University of Missouri-Columbia, 134 Research Park Drive, Columbia, MO, 65211, USA,
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82
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Role of astrocytes in memory and psychiatric disorders. ACTA ACUST UNITED AC 2014; 108:240-51. [PMID: 25169821 DOI: 10.1016/j.jphysparis.2014.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 04/12/2014] [Accepted: 08/18/2014] [Indexed: 01/10/2023]
Abstract
Over the past decade, the traditional description of astrocytes as being merely accessories to brain function has shifted to one in which their role has been pushed into the forefront of importance. Current views suggest that astrocytes:(1) are excitable through calcium fluctuations and respond to neurotransmitters released at synapses; (2) communicate with each other via calcium waves and release their own gliotransmitters which are essential for synaptic plasticity; (3) activate hundreds of synapses at once, thereby synchronizing neuronal activity and activating or inhibiting complete neuronal networks; (4) release vasoactive substances to the smooth muscle surrounding blood vessels enabling the coupling of circulation (blood flow) to local brain activity; and (5) release lactate in an activity-dependent manner in order to supply neuronal metabolic demand. In consequence, the role of astrocytes and astrocytic gliotransmitters is now believed to be critical for higher brain function and recently, evidence begins to gather suggesting that astrocytes are pivotal for learning and memory. All of the above are reviewed here while focusing on the role of astrocytes in memory and psychiatric disorders.
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83
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The actual intrinsic excitability of granular cells determines the ruling neurovascular coupling mechanism in the rat dentate gyrus. J Neurosci 2014; 34:8529-45. [PMID: 24948808 DOI: 10.1523/jneurosci.0472-14.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Paired-pulse stimulation of the perforant pathway was used to study the relation between granular cell activity and the resultant fMRI response in the rat dentate gyrus. By varying the interpulse interval (IPI), paired-pulse stimulations caused: a depression (20 ms IPI), a facilitation (100 ms IPI), a mixture of depression and facilitation (30 ms IPI), or no change (500 ms IPS) in the second response. Eight identical paired pulses were applied during one stimulation train and the evoked field potentials and generated fMRI responses were measured simultaneously. Application of consecutive stimulation trains caused time-dependent variations in electrophysiological and fMRI responses, which were characteristic for each stimulus protocol. Depending on the IPI, the magnitude of the fMRI response either correlated strongly with or was apparently unrelated to the spiking or postsynaptic activity of the granular cells. A strong relation between spiking activity and resultant fMRI response was only found when the stimulation protocol caused an increase in the recorded population spike latency. If the latency was decreased, the fMRI response was more closely related to the applied input activity. Perforant pathway fibers monosynaptically activate granular cells, so variations in population spike latencies reflect changes in their intrinsic excitability. Therefore, during increased intrinsic excitability, signaling cascades upstream of the granular cells determine the fMRI response, whereas granular cell activity-related mechanisms control the fMRI response during decreased intrinsic excitability.
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84
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Tucsek Z, Toth P, Tarantini S, Sosnowska D, Gautam T, Warrington JP, Giles CB, Wren JD, Koller A, Ballabh P, Sonntag WE, Ungvari Z, Csiszar A. Aging exacerbates obesity-induced cerebromicrovascular rarefaction, neurovascular uncoupling, and cognitive decline in mice. J Gerontol A Biol Sci Med Sci 2014; 69:1339-52. [PMID: 24895269 DOI: 10.1093/gerona/glu080] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Epidemiological studies show that obesity has deleterious effects on the brain and cognitive function in the elderly population. However, the specific mechanisms through which aging and obesity interact to promote cognitive decline remain unclear. To test the hypothesis that aging exacerbates obesity-induced cerebromicrovascular impairment, we compared young (7 months) and aged (24 months) high-fat diet-fed obese C57BL/6 mice. We found that aging exacerbates the obesity-induced decline in microvascular density both in the hippocampus and in the cortex. The extent of hippocampal microvascular rarefaction and the extent of impairment of hippocampal-dependent cognitive function positively correlate. Aging exacerbates obesity-induced loss of pericyte coverage on cerebral microvessels and alters hippocampal angiogenic gene expression signature, which likely contributes to microvascular rarefaction. Aging also exacerbates obesity-induced oxidative stress and induction of NADPH oxidase and impairs cerebral blood flow responses to whisker stimulation. Collectively, obesity exerts deleterious cerebrovascular effects in aged mice, promoting cerebromicrovascular rarefaction and neurovascular uncoupling. The morphological and functional impairment of the cerebral microvasculature in association with increased blood-brain barrier disruption and neuroinflammation (Tucsek Z, Toth P, Sosnowsk D, et al. Obesity in aging exacerbates blood-brain barrier disruption, neuroinflammation and oxidative stress in the mouse hippocampus: effects on expression of genes involved in beta-amyloid generation and Alzheimer's disease. J Gerontol Biol Med Sci. 2013. In press, PMID: 24269929) likely contribute to obesity-induced cognitive decline in aging.
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Affiliation(s)
- Zsuzsanna Tucsek
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center.
| | - Peter Toth
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center.
| | - Stefano Tarantini
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center
| | - Danuta Sosnowska
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center
| | - Tripti Gautam
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center
| | - Junie P Warrington
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center. Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson
| | - Cory B Giles
- Oklahoma Medical Research Foundation, Arthritis and Clinical Immunology Research Program
| | - Jonathan D Wren
- Oklahoma Medical Research Foundation, Arthritis and Clinical Immunology Research Program
| | - Akos Koller
- Department of Pathophysiology and Gerontology, Medical School and Szentágothai Research Center, University of Pecs, Hungary
| | - Praveen Ballabh
- Departments of Pediatrics, Anatomy and Cell Biology, New York Medical College-Westchester Medical Center, Valhalla
| | - William E Sonntag
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center
| | - Zoltan Ungvari
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center. Department of Pathophysiology and Gerontology, Medical School and Szentágothai Research Center, University of Pecs, Hungary. Department of Physiology, University of Oklahoma Health Sciences Center.
| | - Anna Csiszar
- Donald W. Reynolds Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center. Department of Pathophysiology and Gerontology, Medical School and Szentágothai Research Center, University of Pecs, Hungary. Department of Physiology, University of Oklahoma Health Sciences Center
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Linne ML, Jalonen TO. Astrocyte-neuron interactions: from experimental research-based models to translational medicine. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 123:191-217. [PMID: 24560146 DOI: 10.1016/b978-0-12-397897-4.00005-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this chapter, we review the principal astrocyte functions and the interactions between neurons and astrocytes. We then address how the experimentally observed functions have been verified in computational models and review recent experimental literature on astrocyte-neuron interactions. Benefits of computational neuroscience work are highlighted through selected studies with neurons and astrocytes by analyzing the existing models qualitatively and assessing the relevance of these models to experimental data. Common strategies to mathematical modeling and computer simulation in neuroscience are summarized for the nontechnical reader. The astrocyte-neuron interactions are then further illustrated by examples of some neurological and neurodegenerative diseases, where the miscommunication between glia and neurons is found to be increasingly important.
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Affiliation(s)
- Marja-Leena Linne
- Computational Neuroscience Group, Department of Signal Processing, Tampere University of Technology, Tampere, Finland
| | - Tuula O Jalonen
- Department of Physiology and Neuroscience, St. George's University, School of Medicine, Grenada, West Indies
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Toth P, Tarantini S, Tucsek Z, Ashpole NM, Sosnowska D, Gautam T, Ballabh P, Koller A, Sonntag WE, Csiszar A, Ungvari Z. Resveratrol treatment rescues neurovascular coupling in aged mice: role of improved cerebromicrovascular endothelial function and downregulation of NADPH oxidase. Am J Physiol Heart Circ Physiol 2013; 306:H299-308. [PMID: 24322615 DOI: 10.1152/ajpheart.00744.2013] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Moment-to-moment adjustment of cerebral blood flow (CBF) to neuronal activity via neurovascular coupling is essential for the maintenance of normal neuronal function. Increased oxidative stress that occurs with aging was shown to impair neurovascular coupling, which likely contributes to a significant age-related decline in higher cortical function, increasing the risk for vascular cognitive impairment. Resveratrol is a polyphenolic compound that exerts significant antiaging protective effects in large vessels, but its effects on the cerebromicrovasculature remain poorly defined. The present study was undertaken to investigate the capacity of resveratrol to improve neurovascular coupling in aging. In aged (24-mo-old) C57BL/6 mice N(ω)-nitro-l-arginine methyl ester-sensitive, nitric oxide-mediated CBF responses to whisker stimulation and to the endothelium-dependent dilator acethylcholine (ACh) were impaired compared with those in young (3-mo-old) mice. Treatment of aged mice with resveratrol rescued neurovascular coupling and ACh-induced responses, which was associated with downregulation of cortical expression of NADPH oxidase and decreased levels of biomarkers of oxidative/nitrative stress (3-nitrotyrosine, 8-isoprostanes). Resveratrol also attenuated age-related increases in reactive oxygen species (ROS) production in cultured cerebromicrovascular endothelial cells (DCF fluorescence, flow cytometry). In conclusion, treatment with resveratrol rescues cortical neurovascular coupling responses to increased neuronal activity in aged mice, likely by restoring cerebromicrovascular endothelial function via downregulation of NADPH oxidase-derived ROS production. Beneficial cerebromicrovascular effects of resveratrol may contribute to its protective effects on cognitive function in aging.
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Affiliation(s)
- Peter Toth
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Dunn KM, Nelson MT. Neurovascular signaling in the brain and the pathological consequences of hypertension. Am J Physiol Heart Circ Physiol 2013; 306:H1-14. [PMID: 24163077 DOI: 10.1152/ajpheart.00364.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The execution and maintenance of all brain functions are dependent on a continuous flow of blood to meet the metabolic needs of the tissue. To ensure the delivery of resources required for neural processing and the maintenance of neural homeostasis, the cerebral vasculature is elaborately and extensively regulated by signaling from neurons, glia, interneurons, and perivascular nerves. Hypertension is associated with impaired neurovascular regulation of the cerebral circulation and culminates in neurodegeneration and cognitive dysfunction. Here, we review the physiological processes of neurovascular signaling in the brain and discuss mechanisms of hypertensive neurovascular dysfunction.
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Affiliation(s)
- Kathryn M Dunn
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, Vermont; and
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Stobart JL, Anderson CM. Multifunctional role of astrocytes as gatekeepers of neuronal energy supply. Front Cell Neurosci 2013; 7:38. [PMID: 23596393 PMCID: PMC3622037 DOI: 10.3389/fncel.2013.00038] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/26/2013] [Indexed: 01/01/2023] Open
Abstract
Dynamic adjustments to neuronal energy supply in response to synaptic activity are critical for neuronal function. Glial cells known as astrocytes have processes that ensheath most central synapses and express G-protein-coupled neurotransmitter receptors and transporters that respond to neuronal activity. Astrocytes also release substrates for neuronal oxidative phosphorylation and have processes that terminate on the surface of brain arterioles and can influence vascular smooth muscle tone and local blood flow. Membrane receptor or transporter-mediated effects of glutamate represent a convergence point of astrocyte influence on neuronal bioenergetics. Astrocytic glutamate uptake drives glycolysis and subsequent shuttling of lactate from astrocytes to neurons for oxidative metabolism. Astrocytes also convert synaptically reclaimed glutamate to glutamine, which is returned to neurons for glutamate salvage or oxidation. Finally, astrocytes store brain energy currency in the form of glycogen, which can be mobilized to produce lactate for neuronal oxidative phosphorylation in response to glutamatergic neurotransmission. These mechanisms couple synaptically driven astrocytic responses to glutamate with release of energy substrates back to neurons to match demand with supply. In addition, astrocytes directly influence the tone of penetrating brain arterioles in response to glutamatergic neurotransmission, coordinating dynamic regulation of local blood flow. We will describe the role of astrocytes in neurometabolic and neurovascular coupling in detail and discuss, in turn, how astrocyte dysfunction may contribute to neuronal bioenergetic deficit and neurodegeneration. Understanding the role of astrocytes as a hub for neurometabolic and neurovascular coupling mechanisms is a critical underpinning for therapeutic development in a broad range of neurodegenerative disorders characterized by chronic generalized brain ischemia and brain microvascular dysfunction.
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Affiliation(s)
- Jillian L Stobart
- Division of Neurodegenerative Disorders, Department of Pharmacology and Therapeutics, St. Boniface Hospital Research, University of Manitoba Winnipeg, MB, Canada ; Department of Nuclear Medicine, Institute of Pharmacology and Toxicology, University of Zürich Zürich, Switzerland
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