101
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Daulatzai MA. Cerebral hypoperfusion and glucose hypometabolism: Key pathophysiological modulators promote neurodegeneration, cognitive impairment, and Alzheimer's disease. J Neurosci Res 2016; 95:943-972. [PMID: 27350397 DOI: 10.1002/jnr.23777] [Citation(s) in RCA: 263] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/06/2016] [Accepted: 05/07/2016] [Indexed: 02/06/2023]
Abstract
Aging, hypertension, diabetes, hypoxia/obstructive sleep apnea (OSA), obesity, vitamin B12/folate deficiency, depression, and traumatic brain injury synergistically promote diverse pathological mechanisms including cerebral hypoperfusion and glucose hypometabolism. These risk factors trigger neuroinflammation and oxidative-nitrosative stress that in turn decrease nitric oxide and enhance endothelin, Amyloid-β deposition, cerebral amyloid angiopathy, and blood-brain barrier disruption. Proinflammatory cytokines, endothelin-1, and oxidative-nitrosative stress trigger several pathological feedforward and feedback loops. These upstream factors persist in the brain for decades, upregulating amyloid and tau, before the cognitive decline. These cascades lead to neuronal Ca2+ increase, neurodegeneration, cognitive/memory decline, and Alzheimer's disease (AD). However, strategies are available to attenuate cerebral hypoperfusion and glucose hypometabolism and ameliorate cognitive decline. AD is the leading cause of dementia among the elderly. There is significant evidence that pathways involving inflammation and oxidative-nitrosative stress (ONS) play a key pathophysiological role in promoting cognitive dysfunction. Aging and several comorbid conditions mentioned above promote diverse pathologies. These include inflammation, ONS, hypoperfusion, and hypometabolism in the brain. In AD, chronic cerebral hypoperfusion and glucose hypometabolism precede decades before the cognitive decline. These comorbid disease conditions may share and synergistically activate these pathophysiological pathways. Inflammation upregulates cerebrovascular pathology through proinflammatory cytokines, endothelin-1, and nitric oxide (NO). Inflammation-triggered ONS promotes long-term damage involving fatty acids, proteins, DNA, and mitochondria; these amplify and perpetuate several feedforward and feedback pathological loops. The latter includes dysfunctional energy metabolism (compromised mitochondrial ATP production), amyloid-β generation, endothelial dysfunction, and blood-brain-barrier disruption. These lead to decreased cerebral blood flow and chronic cerebral hypoperfusion- that would modulate metabolic dysfunction and neurodegeneration. In essence, hypoperfusion deprives the brain from its two paramount trophic substances, viz., oxygen and nutrients. Consequently, the brain suffers from synaptic dysfunction and neuronal degeneration/loss, leading to both gray and white matter atrophy, cognitive dysfunction, and AD. This Review underscores the importance of treating the above-mentioned comorbid disease conditions to attenuate inflammation and ONS and ameliorate decreased cerebral blood flow and hypometabolism. Additionally, several strategies are described here to control chronic hypoperfusion of the brain and enhance cognition. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Mak Adam Daulatzai
- Sleep Disorders Group, EEE Dept/MSE, The University of Melbourne, Parkville, Victoria, Australia
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102
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van de Haar HJ, Jansen JFA, van Osch MJP, van Buchem MA, Muller M, Wong SM, Hofman PAM, Burgmans S, Verhey FRJ, Backes WH. Neurovascular unit impairment in early Alzheimer's disease measured with magnetic resonance imaging. Neurobiol Aging 2016; 45:190-196. [PMID: 27459939 DOI: 10.1016/j.neurobiolaging.2016.06.006] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/03/2016] [Accepted: 06/10/2016] [Indexed: 12/21/2022]
Abstract
The neurovascular unit, which protects neuronal cells and supplies them with essential molecules, plays an important role in the pathophysiology of Alzheimer's Disease (AD). The aim of this study was to noninvasively investigate 2 linked functional elements of the neurovascular unit, blood-brain barrier (BBB) permeability and cerebral blood flow (CBF), in patients with early AD and healthy controls. Therefore, both dynamic contrast-enhanced magnetic resonance imaging and arterial spin labeling magnetic resonance imaging were applied to measure BBB permeability and CBF, respectively. The patients with early AD showed significantly lower CBF and local blood volume in the gray matter, compared with controls. In the patients, we also found that a reduction in CBF is correlated with an increase in leakage rate. This finding supports the hypothesis that neurovascular damage, and in particular impairment of the neurovascular unit constitutes the pathophysiological link between CBF reduction and BBB impairment in AD.
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Affiliation(s)
- Harm J van de Haar
- Departments of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; Department of Neuropsychology and Psychiatry/Alzheimer Center Limburg, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Jacobus F A Jansen
- Departments of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | | | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Majon Muller
- Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Sau May Wong
- Departments of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Paul A M Hofman
- Departments of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Saartje Burgmans
- Department of Neuropsychology and Psychiatry/Alzheimer Center Limburg, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Frans R J Verhey
- Department of Neuropsychology and Psychiatry/Alzheimer Center Limburg, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Walter H Backes
- Departments of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
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103
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Calderón-Garcidueñas L, Reynoso-Robles R, Vargas-Martínez J, Gómez-Maqueo-Chew A, Pérez-Guillé B, Mukherjee PS, Torres-Jardón R, Perry G, Gónzalez-Maciel A. Prefrontal white matter pathology in air pollution exposed Mexico City young urbanites and their potential impact on neurovascular unit dysfunction and the development of Alzheimer's disease. ENVIRONMENTAL RESEARCH 2016; 146:404-17. [PMID: 26829765 DOI: 10.1016/j.envres.2015.12.031] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/30/2015] [Accepted: 12/27/2015] [Indexed: 05/20/2023]
Abstract
Millions of urban children are chronically exposed to high concentrations of air pollutants, i.e., fine particulate matter (PM2.5) and ozone, associated with increased risk for Alzheimer's disease. Compared with children living with clear air those in Mexico City (MC) exhibit systemic, brain and intrathecal inflammation, low CSF Aβ42, breakdown of the BBB, attention and short-term memory deficits, prefrontal white matter hyperintensities, damage to epithelial and endothelial barriers, tight junction and neural autoantibodies, and Alzheimer and Parkinson's hallmarks. The prefrontal white matter is a target of air pollution. We examined by light and electron microscopy the prefrontal white matter of MC dogs (n: 15, age 3.17±0.74 years), children and teens (n: 34, age: 12.64±4.2 years) versus controls. Major findings in MC residents included leaking capillaries and small arterioles with extravascular lipids and erythrocytes, lipofuscin in pericytes, smooth muscle and endothelial cells (EC), thickening of cerebrovascular basement membranes with small deposits of amyloid, patchy absence of the perivascular glial sheet, enlarged Virchow-Robin spaces and nanosize particles (20-48nm) in EC, basement membranes, axons and dendrites. Tight junctions, a key component of the neurovascular unit (NVU) were abnormal in MC versus control dogs (χ(2)<0.0001), and white matter perivascular damage was significantly worse in MC dogs (p=0.002). The integrity of the NVU, an interactive network of vascular, glial and neuronal cells is compromised in MC young residents. Characterizing the early NVU damage and identifying biomarkers of neurovascular dysfunction may provide a fresh insight into Alzheimer pathogenesis and open opportunities for pediatric neuroprotection.
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Affiliation(s)
- Lilian Calderón-Garcidueñas
- The University of Montana, Missoula, MT 59812, USA; Universidad del Valle de México, Mexico City 04850, México.
| | | | | | | | | | | | - Ricardo Torres-Jardón
- Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Mexico City 04310, México
| | - George Perry
- College of Sciences, University of Texas at San Antonio, San Antonio, TX, USA
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104
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Phillips AA, Chan FH, Zheng MMZ, Krassioukov AV, Ainslie PN. Neurovascular coupling in humans: Physiology, methodological advances and clinical implications. J Cereb Blood Flow Metab 2016; 36:647-64. [PMID: 26661243 PMCID: PMC4821024 DOI: 10.1177/0271678x15617954] [Citation(s) in RCA: 256] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/16/2022]
Abstract
Neurovascular coupling reflects the close temporal and regional linkage between neural activity and cerebral blood flow. Although providing mechanistic insight, our understanding of neurovascular coupling is largely limited to non-physiologicalex vivopreparations and non-human models using sedatives/anesthetics with confounding cerebrovascular implications. Herein, with particular focus on humans, we review the present mechanistic understanding of neurovascular coupling and highlight current approaches to assess these responses and the application in health and disease. Moreover, we present new guidelines for standardizing the assessment of neurovascular coupling in humans. To improve the reliability of measurement and related interpretation, the utility of new automated software for neurovascular coupling is demonstrated, which provides the capacity for coalescing repetitive trials and time intervals into single contours and extracting numerous metrics (e.g., conductance and pulsatility, critical closing pressure, etc.) according to patterns of interest (e.g., peak/minimum response, time of response, etc.). This versatile software also permits the normalization of neurovascular coupling metrics to dynamic changes in arterial blood gases, potentially influencing the hyperemic response. It is hoped that these guidelines, combined with the newly developed and openly available software, will help to propel the understanding of neurovascular coupling in humans and also lead to improved clinical management of this critical physiological function.
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Affiliation(s)
- Aaron A Phillips
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada
| | - Franco Hn Chan
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada
| | - Mei Mu Zi Zheng
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada
| | - Andrei V Krassioukov
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada Department of Physical Therapy, UBC, Vancouver, Canada GF Strong Rehabilitation Center, Vancouver, Canada Department of Medicine, Division of Physical Medicine and Rehabilitation, UBC, Vancouver, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
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105
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Guo S, Lok J, Zhao S, Leung W, Som AT, Hayakawa K, Wang Q, Xing C, Wang X, Ji X, Zhou Y, Lo EH. Effects of Controlled Cortical Impact on the Mouse Brain Vasculome. J Neurotrauma 2016; 33:1303-16. [PMID: 26528928 DOI: 10.1089/neu.2015.4101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Perturbations in blood vessels play a critical role in the pathophysiology of brain injury and neurodegeneration. Here, we use a systematic genome-wide transcriptome screening approach to investigate the vasculome after brain trauma in mice. Mice were subjected to controlled cortical impact and brains were extracted for analysis at 24 h post-injury. The core of the traumatic lesion was removed and then cortical microvesels were isolated from nondirectly damaged ipsilateral cortex. Compared to contralateral cortex and normal cortex from sham-operated mice, we identified a wide spectrum of responses in the vasculome after trauma. Up-regulated pathways included those involved in regulation of inflammation and extracellular matrix processes. Decreased pathways included those involved in regulation of metabolism, mitochondrial function, and transport systems. These findings suggest that microvascular perturbations can be widespread and not necessarily localized to core areas of direct injury per se and may further provide a broader gene network context for existing knowledge regarding inflammation, metabolism, and blood-brain barrier alterations after brain trauma. Further efforts are warranted to map the vasculome with higher spatial and temporal resolution from acute to delayed phase post-trauma. Investigating the widespread network responses in the vasculome may reveal potential mechanisms, therapeutic targets, and biomarkers for traumatic brain injury.
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Affiliation(s)
- Shuzhen Guo
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Josephine Lok
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts.,2 Department of Pediatrics, Massachusetts General Hospital , Harvard Medical School, Boston, Massachusetts
| | - Song Zhao
- 3 The Department of Spine Surgery, the First Hospital of Jilin University , Changchun, China
| | - Wendy Leung
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Angel T Som
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Kazuhide Hayakawa
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Qingzhi Wang
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Changhong Xing
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Xiaoying Wang
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Xunming Ji
- 4 Cerebrovascular Research Center, Department of Neurosurgery, Xuanwu Hospital, Capital Medical University , Beijing, China
| | - Yiming Zhou
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
| | - Eng H Lo
- 1 Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital , Harvard Medical School, Charlestown, Massachusetts
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106
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A New Computational Model for Neuro-Glio-Vascular Coupling: Astrocyte Activation Can Explain Cerebral Blood Flow Nonlinear Response to Interictal Events. PLoS One 2016; 11:e0147292. [PMID: 26849643 PMCID: PMC4743967 DOI: 10.1371/journal.pone.0147292] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 01/01/2016] [Indexed: 12/31/2022] Open
Abstract
Developing a clear understanding of the relationship between cerebral blood flow (CBF) response and neuronal activity is of significant importance because CBF increase is essential to the health of neurons, for instance through oxygen supply. This relationship can be investigated by analyzing multimodal (fMRI, PET, laser Doppler…) recordings. However, the important number of intermediate (non-observable) variables involved in the underlying neurovascular coupling makes the discovery of mechanisms all the more difficult from the sole multimodal data. We present a new computational model developed at the population scale (voxel) with physiologically relevant but simple equations to facilitate the interpretation of regional multimodal recordings. This model links neuronal activity to regional CBF dynamics through neuro-glio-vascular coupling. This coupling involves a population of glial cells called astrocytes via their role in neurotransmitter (glutamate and GABA) recycling and their impact on neighboring vessels. In epilepsy, neuronal networks generate epileptiform discharges, leading to variations in astrocytic and CBF dynamics. In this study, we took advantage of these large variations in neuronal activity magnitude to test the capacity of our model to reproduce experimental data. We compared simulations from our model with isolated epileptiform events, which were obtained in vivo by simultaneous local field potential and laser Doppler recordings in rats after local bicuculline injection. We showed a predominant neuronal contribution for low level discharges and a significant astrocytic contribution for higher level discharges. Besides, neuronal contribution to CBF was linear while astrocytic contribution was nonlinear. Results thus indicate that the relationship between neuronal activity and CBF magnitudes can be nonlinear for isolated events and that this nonlinearity is due to astrocytic activity, highlighting the importance of astrocytes in the interpretation of regional recordings.
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107
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Benyó Z, Ruisanchez É, Leszl-Ishiguro M, Sándor P, Pacher P. Endocannabinoids in cerebrovascular regulation. Am J Physiol Heart Circ Physiol 2016; 310:H785-801. [PMID: 26825517 DOI: 10.1152/ajpheart.00571.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 01/25/2016] [Indexed: 02/08/2023]
Abstract
The cerebral blood flow is tightly regulated by myogenic, endothelial, metabolic, and neural mechanisms under physiological conditions, and a large body of recent evidence indicates that inflammatory pathways have a major influence on the cerebral blood perfusion in certain central nervous system disorders, like hemorrhagic and ischemic stroke, traumatic brain injury, and vascular dementia. All major cell types involved in cerebrovascular control pathways (i.e., smooth muscle, endothelium, neurons, astrocytes, pericytes, microglia, and leukocytes) are capable of synthesizing endocannabinoids and/or express some or several of their target proteins [i.e., the cannabinoid 1 and 2 (CB1 and CB2) receptors and the transient receptor potential vanilloid type 1 ion channel]. Therefore, the endocannabinoid system may importantly modulate the regulation of cerebral circulation under physiological and pathophysiological conditions in a very complex manner. Experimental data accumulated since the late 1990s indicate that the direct effect of cannabinoids on cerebral vessels is vasodilation mediated, at least in part, by CB1 receptors. Cannabinoid-induced cerebrovascular relaxation involves both a direct inhibition of smooth muscle contractility and a release of vasodilator mediator(s) from the endothelium. However, under stress conditions (e.g., in conscious restrained animals or during hypoxia and hypercapnia), cannabinoid receptor activation was shown to induce a reduction of the cerebral blood flow, probably via inhibition of the electrical and/or metabolic activity of neurons. Finally, in certain cerebrovascular pathologies (e.g., subarachnoid hemorrhage, as well as traumatic and ischemic brain injury), activation of CB2 (and probably yet unidentified non-CB1/non-CB2) receptors appear to improve the blood perfusion of the brain via attenuating vascular inflammation.
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Affiliation(s)
- Zoltán Benyó
- Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary; and
| | - Éva Ruisanchez
- Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary; and
| | - Miriam Leszl-Ishiguro
- Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary; and
| | - Péter Sándor
- Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary; and
| | - Pál Pacher
- Laboratory of Cardiovascular Physiology and Tissue Injury, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
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108
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Kenney K, Amyot F, Haber M, Pronger A, Bogoslovsky T, Moore C, Diaz-Arrastia R. Cerebral Vascular Injury in Traumatic Brain Injury. Exp Neurol 2016; 275 Pt 3:353-366. [DOI: 10.1016/j.expneurol.2015.05.019] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/19/2015] [Accepted: 05/26/2015] [Indexed: 12/14/2022]
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109
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Heinonen I, Kalliokoski KK, Hannukainen JC, Duncker DJ, Nuutila P, Knuuti J. Organ-specific physiological responses to acute physical exercise and long-term training in humans. Physiology (Bethesda) 2015; 29:421-36. [PMID: 25362636 DOI: 10.1152/physiol.00067.2013] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Virtually all tissues in the human body rely on aerobic metabolism for energy production and are therefore critically dependent on continuous supply of oxygen. Oxygen is provided by blood flow, and, in essence, changes in organ perfusion are also closely associated with alterations in tissue metabolism. In response to acute exercise, blood flow is markedly increased in contracting skeletal muscles and myocardium, but perfusion in other organs (brain and bone) is only slightly enhanced or is even reduced (visceral organs). Despite largely unchanged metabolism and perfusion, repeated exposures to altered hemodynamics and hormonal milieu produced by acute exercise, long-term exercise training appears to be capable of inducing effects also in tissues other than muscles that may yield health benefits. However, the physiological adaptations and driving-force mechanisms in organs such as brain, liver, pancreas, gut, bone, and adipose tissue, remain largely obscure in humans. Along these lines, this review integrates current information on physiological responses to acute exercise and to long-term physical training in major metabolically active human organs. Knowledge is mostly provided based on the state-of-the-art, noninvasive human imaging studies, and directions for future novel research are proposed throughout the review.
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Affiliation(s)
- Ilkka Heinonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku and Turku University Hospital, Turku, Finland; Department of Cardiology, Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Kari K Kalliokoski
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Jarna C Hannukainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Dirk J Duncker
- Department of Cardiology, Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Medicine, University of Turku and Turku University Hospital, Turku, Finland; and
| | - Juhani Knuuti
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
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110
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Kim SS, Lee BH. Measuring cerebral hemodynamic changes during action observation with functional transcranial doppler. J Phys Ther Sci 2015; 27:1379-81. [PMID: 26157224 PMCID: PMC4483402 DOI: 10.1589/jpts.27.1379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/11/2015] [Indexed: 12/31/2022] Open
Abstract
[Purpose] The purpose of this study was to investigate the effects of action observation
training (AOT) on cerebral hemodynamic changes including cerebral blood flow velocity
(CBFV) and cerebral blood flow volume (CBFvol) in healthy subjects. [Subjects] Fifteen
healthy subjects participated in this study. [Methods] All subjects were educated
regarding AOT, and systolic peak velocity (Vs) as well as mean flow velocity (Vm) in the
middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral
artery (PCA) were evaluated using functional transcranial doppler with a 2-MHz probe,
before and after performing AOT. [Results] Healthy subjects showed significant differences
in Vs and Vm in the MCA, ACA, and PCA after AOT compared with those before AOT.
[Conclusion] Our findings indicate that AOT has a positive effect in terms of an increase
in CBFV and CBFvol in healthy subjects, since the brain requires more blood to meet the
metabolic demand during AOT.
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Affiliation(s)
- Seong-Sik Kim
- Department of Physical Therapy, Sahmyook University: 815 Hwarang-ro, Nowon-gu, Seoul 139-742, Republic of Korea
| | - Byoung-Hee Lee
- Department of Physical Therapy, Sahmyook University: 815 Hwarang-ro, Nowon-gu, Seoul 139-742, Republic of Korea
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111
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Abstract
The brain, which represents 2% of body mass but consumes 20% of body energy at rest, has a limited capacity to store energy and is therefore highly dependent on oxygen and glucose supply from the blood stream. Normal functioning of neural circuits thus relies on adequate matching between metabolic needs and blood supply. Moreover, not only does the brain need to be densely vascularized, it also requires a tightly controlled environment free of toxins and pathogens to provide the proper chemical composition for synaptic transmission and neuronal function. In this review, we focus on three major factors that ensure optimal brain perfusion and function: the patterning of vascular networks to efficiently deliver blood and nutrients, the function of the blood-brain barrier to maintain brain homeostasis, and the regulation of cerebral blood flow to adequately couple energy supply to neural function.
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Affiliation(s)
- Benjamin J Andreone
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115; , ,
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112
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Lacoste B, Gu C. Control of cerebrovascular patterning by neural activity during postnatal development. Mech Dev 2015; 138 Pt 1:43-9. [PMID: 26116138 DOI: 10.1016/j.mod.2015.06.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 05/26/2015] [Accepted: 06/16/2015] [Indexed: 01/08/2023]
Abstract
The brain represents only a small portion of the body mass and yet consumes almost a quarter of the available energy, and has a limited ability to store energy. The brain is therefore highly dependent on oxygen and nutrient supply from the blood circulation, which makes it vulnerable to vascular pathologies. Key vascular determinants will ensure proper brain maturation and function: the establishment of vascular networks, the formation of the blood-brain barrier, and the regulation of blood flow. Recent evidence suggests that the phenomenon of neurovascular coupling, during which increased neural activity normally leads to increased blood flow, is not functional until few weeks after birth, implying that the developing brain must rely on alternative mechanisms to adequately couple blood supply to increasing energy demands. This review will focus on these alternative mechanisms, which have been partly elucidated recently via the demonstration that neural activity influences the maturation of cerebrovascular networks. We also propose possible mechanisms underlying activity-induced vascular plasticity.
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Affiliation(s)
- Baptiste Lacoste
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
| | - Chenghua Gu
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
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113
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Mark CI, Mazerolle EL, Chen JJ. Metabolic and vascular origins of the BOLD effect: Implications for imaging pathology and resting-state brain function. J Magn Reson Imaging 2015; 42:231-46. [DOI: 10.1002/jmri.24786] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 09/02/2014] [Indexed: 01/08/2023] Open
Affiliation(s)
- Clarisse I. Mark
- Centre for Neuroscience Studies; Queen's University; Kingston ON Canada
| | | | - J. Jean Chen
- Rotman Research Institute, Baycrest, University of Toronto; Toronto ON Canada
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114
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Fabjan A, Zaletel M, Žvan B. Is there a persistent dysfunction of neurovascular coupling in migraine? BIOMED RESEARCH INTERNATIONAL 2015; 2015:574186. [PMID: 25705673 PMCID: PMC4331400 DOI: 10.1155/2015/574186] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/02/2014] [Indexed: 12/21/2022]
Abstract
Changes in cerebral blood flow are one of the main features of migraine attack and have inspired the vascular theory of migraine. This traditional view has been reshaped with recent experimental data, which gave rise to the neural theory of migraine. In this review, we speculate that there might be an important link between the two theories, that is, the dysfunction of neurovascular coupling.
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Affiliation(s)
- Andrej Fabjan
- Institute of Physiology, Medical Faculty, University of Ljubljana, Zaloška Cesta 4, 1000 Ljubljana, Slovenia
| | - Marjan Zaletel
- Department of Vascular Neurology, University Clinical Centre, Zaloška Cesta 2, 1000 Ljubljana, Slovenia
| | - Bojana Žvan
- Department of Vascular Neurology, University Clinical Centre, Zaloška Cesta 2, 1000 Ljubljana, Slovenia
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115
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Kousik SM, Napier TC, Ross RD, Sumner DR, Carvey PM. Dopamine receptors and the persistent neurovascular dysregulation induced by methamphetamine self-administration in rats. J Pharmacol Exp Ther 2014; 351:432-9. [PMID: 25185214 DOI: 10.1124/jpet.114.217802] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Recently abstinent methamphetamine (Meth) abusers showed neurovascular dysregulation within the striatum. The factors that contribute to this dysregulation and the persistence of these effects are unclear. The current study addressed these knowledge gaps. First, we evaluated the brains of rats with a history of Meth self-administration following various periods of forced abstinence. Micro-computed tomography revealed a marked reduction in vessel diameter and vascular volume uniquely within the striatum between 1 and 28 days after Meth self-administration. Microvessels showed a greater impairment than larger vessels. Subsequently, we determined that dopamine (DA) D2 receptors regulated Meth-induced striatal vasoconstriction via acute noncontingent administration of Meth. These receptors likely regulated the response to striatal hypoxia, as hypoxia inducible factor 1α was elevated. Acute Meth exposure also increased striatal levels of endothelin receptor A and decreased neuronal nitric oxide synthase. Collectively, the data provide novel evidence that Meth-induced striatal neurovascular dysregulation involves DA receptor signaling that results in vasoconstriction via endothelin receptor A and nitric oxide signaling. As these effects can lead to hypoxia and trigger neuronal damage, these findings provide a mechanistic explanation for the selective striatal toxicity observed in the brains of Meth-abusing humans.
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Affiliation(s)
- Sharanya M Kousik
- Center for Compulsive Behavior and Addiction (S.M.K., T.C.N., P.M.C.), Department of Pharmacology (S.M.K., T.C.N., P.M.C.), Department of Psychiatry (T.C.N.), Department of Neurologic Sciences (P.M.C.), and Department of Anatomy and Cell Biology (R.D.R., D.R.S.), Rush University Medical Center, Chicago, Illinois
| | - T Celeste Napier
- Center for Compulsive Behavior and Addiction (S.M.K., T.C.N., P.M.C.), Department of Pharmacology (S.M.K., T.C.N., P.M.C.), Department of Psychiatry (T.C.N.), Department of Neurologic Sciences (P.M.C.), and Department of Anatomy and Cell Biology (R.D.R., D.R.S.), Rush University Medical Center, Chicago, Illinois
| | - Ryan D Ross
- Center for Compulsive Behavior and Addiction (S.M.K., T.C.N., P.M.C.), Department of Pharmacology (S.M.K., T.C.N., P.M.C.), Department of Psychiatry (T.C.N.), Department of Neurologic Sciences (P.M.C.), and Department of Anatomy and Cell Biology (R.D.R., D.R.S.), Rush University Medical Center, Chicago, Illinois
| | - D Rick Sumner
- Center for Compulsive Behavior and Addiction (S.M.K., T.C.N., P.M.C.), Department of Pharmacology (S.M.K., T.C.N., P.M.C.), Department of Psychiatry (T.C.N.), Department of Neurologic Sciences (P.M.C.), and Department of Anatomy and Cell Biology (R.D.R., D.R.S.), Rush University Medical Center, Chicago, Illinois
| | - Paul M Carvey
- Center for Compulsive Behavior and Addiction (S.M.K., T.C.N., P.M.C.), Department of Pharmacology (S.M.K., T.C.N., P.M.C.), Department of Psychiatry (T.C.N.), Department of Neurologic Sciences (P.M.C.), and Department of Anatomy and Cell Biology (R.D.R., D.R.S.), Rush University Medical Center, Chicago, Illinois
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116
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Bartnik-Olson BL, Holshouser B, Wang H, Grube M, Tong K, Wong V, Ashwal S. Impaired Neurovascular Unit Function Contributes to Persistent Symptoms after Concussion: A Pilot Study. J Neurotrauma 2014; 31:1497-506. [DOI: 10.1089/neu.2013.3213] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Barbara Holshouser
- Department of Radiology, Loma Linda University School of Medicine, Loma Linda, California
| | - Harrison Wang
- Department of Radiology, Loma Linda University School of Medicine, Loma Linda, California
| | - Matthew Grube
- Department of Radiology, Loma Linda University School of Medicine, Loma Linda, California
| | - Karen Tong
- Department of Radiology, Loma Linda University School of Medicine, Loma Linda, California
| | - Valarie Wong
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
| | - Stephen Ashwal
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
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117
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Dormanns K, van Disseldorp EMJ, Brown RG, David T. Neurovascular coupling and the influence of luminal agonists via the endothelium. J Theor Biol 2014; 364:49-70. [PMID: 25167790 DOI: 10.1016/j.jtbi.2014.08.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 08/15/2014] [Accepted: 08/18/2014] [Indexed: 11/18/2022]
Abstract
A numerical model of neurovascular coupling (NVC) is presented based on neuronal activity coupled to vasodilation/contraction models via the astrocytic mediated perivascular K(+) and the smooth muscle cell Ca(2+) pathway. Luminal agonists acting on P2Y receptors on the endothelial cell surface provide a flux of IP3 into the endothelial cytosol. This concentration of IP3 is transported via gap junctions between endothelial and smooth muscle cells providing a source of sacroplasmic derived Ca(2+) in the smooth muscle cell. The model is able to relate a neuronal input signal to the corresponding vessel reaction. Results indicate that blood flow mediated IP3 production via the agonist ATP has a substantial effect on the contraction/dilation dynamics of the SMC. The resulting variation in cytosolic Ca(2+) can enhance and inhibit the flow of blood to the cortical tissue. IP3 coupling between endothelial and smooth muscle cells seems to be important in the dynamics of the smooth muscle cell. The VOCC channels are, due to the hyperpolarisation from K(+) SMC efflux, almost entirely closed and do not seem to play a significant role during neuronal activity. The current model shows that astrocytic Ca(2+) is not necessary for neurovascular coupling to occur in contrast to a number of experiments outlining the importance of astrocytic Ca(2+) in NVC, however this Ca(2+) pathway is not the only one mediating NVC. Importantly agonists in flowing blood have a significant influence on the endothelial and smooth muscle cell dynamics.
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Affiliation(s)
- K Dormanns
- Bluefern Supercomputing Unit, University of Canterbury, Christchurch, New Zealand
| | - E M J van Disseldorp
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - R G Brown
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - T David
- Bluefern Supercomputing Unit, University of Canterbury, Christchurch, New Zealand.
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118
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Afonso-Oramas D, Cruz-Muros I, Castro-Hernández J, Salas-Hernández J, Barroso-Chinea P, García-Hernández S, Lanciego JL, González-Hernández T. Striatal vessels receive phosphorylated tyrosine hydroxylase-rich innervation from midbrain dopaminergic neurons. Front Neuroanat 2014; 8:84. [PMID: 25206324 PMCID: PMC4144090 DOI: 10.3389/fnana.2014.00084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/02/2014] [Indexed: 01/11/2023] Open
Abstract
Nowadays it is assumed that besides its roles in neuronal processing, dopamine (DA) is also involved in the regulation of cerebral blood flow. However, studies on the hemodynamic actions of DA have been mainly focused on the cerebral cortex, but the possibility that vessels in deeper brain structures receive dopaminergic axons and the origin of these axons have not been investigated. Bearing in mind the evidence of changes in the blood flow of basal ganglia in Parkinson's disease (PD), and the pivotal role of the dopaminergic mesostriatal pathway in the pathophysiology of this disease, here we studied whether striatal vessels receive inputs from midbrain dopaminergic neurons. The injection of an anterograde neuronal tracer in combination with immunohistochemistry for dopaminergic, vascular and astroglial markers, and dopaminergic lesions, revealed that midbrain dopaminergic axons are in close apposition to striatal vessels and perivascular astrocytes. These axons form dense perivascular plexuses restricted to striatal regions in rats and monkeys. Interestingly, they are intensely immunoreactive for tyrosine hydroxylase (TH) phosphorylated at Ser19 and Ser40 residues. The presence of phosphorylated TH in vessel terminals indicates they are probably the main source of basal TH activity in the striatum, and that after activation of midbrain dopaminergic neurons, DA release onto vessels precedes that onto neurons. Furthermore, the relative weight of this "vascular component" within the mesostriatal pathway suggests that it plays a relevant role in the pathophysiology of PD.
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Affiliation(s)
- Domingo Afonso-Oramas
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Biomedical Technologies Institute (ITB, CIBICAN)La Laguna, Tenerife, Spain
- Spanish Network of Neurodegenerative Diseases (CIBERNED)Madrid, Spain
| | - Ignacio Cruz-Muros
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Biomedical Technologies Institute (ITB, CIBICAN)La Laguna, Tenerife, Spain
- Spanish Network of Neurodegenerative Diseases (CIBERNED)Madrid, Spain
| | - Javier Castro-Hernández
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Biomedical Technologies Institute (ITB, CIBICAN)La Laguna, Tenerife, Spain
| | - Josmar Salas-Hernández
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Spanish Network of Neurodegenerative Diseases (CIBERNED)Madrid, Spain
| | - Pedro Barroso-Chinea
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Biomedical Technologies Institute (ITB, CIBICAN)La Laguna, Tenerife, Spain
| | | | - José L. Lanciego
- Spanish Network of Neurodegenerative Diseases (CIBERNED)Madrid, Spain
- Center for Applied Medical Research (CIMA), University of NavarraPamplona, Spain
| | - Tomás González-Hernández
- Department of Anatomy, Faculty of Medicine, University of La LagunaLa Laguna, Tenerife, Spain
- Biomedical Technologies Institute (ITB, CIBICAN)La Laguna, Tenerife, Spain
- Spanish Network of Neurodegenerative Diseases (CIBERNED)Madrid, Spain
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119
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Lacoste B, Comin CH, Ben-Zvi A, Kaeser PS, Xu X, Costa LDF, Gu C. Sensory-related neural activity regulates the structure of vascular networks in the cerebral cortex. Neuron 2014; 83:1117-30. [PMID: 25155955 DOI: 10.1016/j.neuron.2014.07.034] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2014] [Indexed: 11/15/2022]
Abstract
Neurovascular interactions are essential for proper brain function. While the effect of neural activity on cerebral blood flow has been extensively studied, whether or not neural activity influences vascular patterning remains elusive. Here, we demonstrate that neural activity promotes the formation of vascular networks in the early postnatal mouse barrel cortex. Using a combination of genetics, imaging, and computational tools to allow simultaneous analysis of neuronal and vascular components, we found that vascular density and branching were decreased in the barrel cortex when sensory input was reduced by either a complete deafferentation, a genetic impairment of neurotransmitter release at thalamocortical synapses, or a selective reduction of sensory-related neural activity by whisker plucking. In contrast, enhancement of neural activity by whisker stimulation led to an increase in vascular density and branching. The finding that neural activity is necessary and sufficient to trigger alterations of vascular networks reveals an important feature of neurovascular interactions.
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Affiliation(s)
- Baptiste Lacoste
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Cesar H Comin
- IFSC, University of Sao Paulo, Sao Carlos, SP, Brazil
| | - Ayal Ben-Zvi
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Xiaoyin Xu
- Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA
| | | | - Chenghua Gu
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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120
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Martin C. Contributions and complexities from the use of in vivo animal models to improve understanding of human neuroimaging signals. Front Neurosci 2014; 8:211. [PMID: 25191214 PMCID: PMC4137227 DOI: 10.3389/fnins.2014.00211] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 07/01/2014] [Indexed: 01/18/2023] Open
Abstract
Many of the major advances in our understanding of how functional brain imaging signals relate to neuronal activity over the previous two decades have arisen from physiological research studies involving experimental animal models. This approach has been successful partly because it provides opportunities to measure both the hemodynamic changes that underpin many human functional brain imaging techniques and the neuronal activity about which we wish to make inferences. Although research into the coupling of neuronal and hemodynamic responses using animal models has provided a general validation of the correspondence of neuroimaging signals to specific types of neuronal activity, it is also highlighting the key complexities and uncertainties in estimating neural signals from hemodynamic markers. This review will detail how research in animal models is contributing to our rapidly evolving understanding of what human neuroimaging techniques tell us about neuronal activity. It will highlight emerging issues in the interpretation of neuroimaging data that arise from in vivo research studies, for example spatial and temporal constraints to neuroimaging signal interpretation, or the effects of disease and modulatory neurotransmitters upon neurovascular coupling. We will also give critical consideration to the limitations and possible complexities of translating data acquired in the typical animals models used in this area to the arena of human fMRI. These include the commonplace use of anesthesia in animal research studies and the fact that many neuropsychological questions that are being actively explored in humans have limited homologs within current animal models for neuroimaging research. Finally we will highlighting approaches, both in experimental animals models (e.g. imaging in conscious, behaving animals) and human studies (e.g. combined fMRI-EEG), that mitigate against these challenges.
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Affiliation(s)
- Chris Martin
- Department of Psychology, The University of Sheffield Sheffield, UK
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121
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Gawryluk JR, Mazerolle EL, D'Arcy RCN. Does functional MRI detect activation in white matter? A review of emerging evidence, issues, and future directions. Front Neurosci 2014; 8:239. [PMID: 25152709 PMCID: PMC4125856 DOI: 10.3389/fnins.2014.00239] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 07/21/2014] [Indexed: 12/13/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) is a non-invasive technique that allows for visualization of activated brain regions. Until recently, fMRI studies have focused on gray matter. There are two main reasons white matter fMRI remains controversial: (1) the blood oxygen level dependent (BOLD) fMRI signal depends on cerebral blood flow and volume, which are lower in white matter than gray matter and (2) fMRI signal has been associated with post-synaptic potentials (mainly localized in gray matter) as opposed to action potentials (the primary type of neural activity in white matter). Despite these observations, there is no direct evidence against measuring fMRI activation in white matter and reports of fMRI activation in white matter continue to increase. The questions underlying white matter fMRI activation are important. White matter fMRI activation has the potential to greatly expand the breadth of brain connectivity research, as well as improve the assessment and diagnosis of white matter and connectivity disorders. The current review provides an overview of the motivation to investigate white matter fMRI activation, as well as the published evidence of this phenomenon. We speculate on possible neurophysiologic bases of white matter fMRI signals, and discuss potential explanations for why reports of white matter fMRI activation are relatively scarce. We end with a discussion of future basic and clinical research directions in the study of white matter fMRI.
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Affiliation(s)
- Jodie R Gawryluk
- Division of Medical Sciences, Department of Psychology, University of Victoria Victoria, BC, Canada
| | - Erin L Mazerolle
- Department of Radiology, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Ryan C N D'Arcy
- Applied Sciences, Simon Fraser University Burnaby, BC, Canada ; Fraser Health Authority, Surrey Memorial Hospital Surrey, BC, Canada
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122
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Zhao Y, Bhattacharjee S, Jones BM, Hill J, Dua P, Lukiw WJ. Regulation of neurotropic signaling by the inducible, NF-kB-sensitive miRNA-125b in Alzheimer's disease (AD) and in primary human neuronal-glial (HNG) cells. Mol Neurobiol 2014; 50:97-106. [PMID: 24293102 PMCID: PMC4038663 DOI: 10.1007/s12035-013-8595-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/13/2013] [Indexed: 12/12/2022]
Abstract
Inducible microRNAs (miRNAs) perform critical regulatory roles in central nervous system (CNS) development, aging, health, and disease. Using miRNA arrays, RNA sequencing, enhanced Northern dot blot hybridization technologies, Western immunoblot, and bioinformatics analysis, we have studied miRNA abundance and complexity in Alzheimer's disease (AD) brain tissues compared to age-matched controls. In both short post-mortem AD and in stressed primary human neuronal-glial (HNG) cells, we observe a consistent up-regulation of several brain-enriched miRNAs that are under transcriptional control by the pro-inflammatory transcription factor NF-kB. These include miRNA-9, miRNA-34a, miRNA-125b, miRNA-146a, and miRNA-155. Of the inducible miRNAs in this subfamily, miRNA-125b is among the most abundant and significantly induced miRNA species in human brain cells and tissues. Bioinformatics analysis indicated that an up-regulated miRNA-125b could potentially target the 3'untranslated region (3'-UTR) of the messenger RNA (mRNA) encoding (a) a 15-lipoxygenase (15-LOX; ALOX15; chr 17p13.3), utilized in the conversion of docosahexaneoic acid into neuroprotectin D1 (NPD1), and (b) the vitamin D3 receptor (VDR; VD3R; chr12q13.11) of the nuclear hormone receptor superfamily. 15-LOX and VDR are key neuromolecular factors essential in lipid-mediated signaling, neurotrophic support, defense against reactive oxygen and nitrogen species (reactive oxygen and nitrogen species), and neuroprotection in the CNS. Pathogenic effects appear to be mediated via specific interaction of miRNA-125b with the 3'-UTR region of the 15-LOX and VDR messenger RNAs (mRNAs). In AD hippocampal CA1 and in stressed HNG cells, 15-LOX and VDR down-regulation and a deficiency in neurotrophic support may therefore be explained by the actions of a single inducible, pro-inflammatory miRNA-125b. We will review the recent data on the pathogenic actions of this up-regulated miRNA-125b in AD and discuss potential therapeutic approaches using either anti-NF-kB or anti-miRNA-125b strategies. These may be of clinical relevance in the restoration of 15-LOX and VDR expression back to control levels and the re-establishment of homeostatic neurotrophic signaling in the CNS.
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Affiliation(s)
- Yuhai Zhao
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
| | - Surjyadipta Bhattacharjee
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
| | - Brandon M. Jones
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
| | - Jim Hill
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
- Department of Microbiology, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
| | - Prerna Dua
- Department of Health Information Management, Louisiana State University, Ruston, LA 71272 USA
| | - Walter J. Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
- Department of Neurology, Louisiana State University Health Sciences Center, New Orleans LA 70112 USA
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123
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Huf W, Kalcher K, Boubela RN, Rath G, Vecsei A, Filzmoser P, Moser E. On the generalizability of resting-state fMRI machine learning classifiers. Front Hum Neurosci 2014; 8:502. [PMID: 25120443 PMCID: PMC4114329 DOI: 10.3389/fnhum.2014.00502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 06/20/2014] [Indexed: 12/13/2022] Open
Abstract
Machine learning classifiers have become increasingly popular tools to generate single-subject inferences from fMRI data. With this transition from the traditional group level difference investigations to single-subject inference, the application of machine learning methods can be seen as a considerable step forward. Existing studies, however, have given scarce or no information on the generalizability to other subject samples, limiting the use of such published classifiers in other research projects. We conducted a simulation study using publicly available resting-state fMRI data from the 1000 Functional Connectomes and COBRE projects to examine the generalizability of classifiers based on regional homogeneity of resting-state time series. While classification accuracies of up to 0.8 (using sex as the target variable) could be achieved on test datasets drawn from the same study as the training dataset, the generalizability of classifiers to different study samples proved to be limited albeit above chance. This shows that on the one hand a certain amount of generalizability can robustly be expected, but on the other hand this generalizability should not be overestimated. Indeed, this study substantiates the need to include data from several sites in a study investigating machine learning classifiers with the aim of generalizability.
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Affiliation(s)
- Wolfgang Huf
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna Vienna, Austria ; MR Centre of Excellence, Medical University of Vienna Vienna, Austria ; Department of Statistics and Probability Theory, Vienna University of Technology Vienna, Austria
| | - Klaudius Kalcher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna Vienna, Austria ; MR Centre of Excellence, Medical University of Vienna Vienna, Austria ; Department of Statistics and Probability Theory, Vienna University of Technology Vienna, Austria
| | - Roland N Boubela
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna Vienna, Austria ; MR Centre of Excellence, Medical University of Vienna Vienna, Austria ; Department of Statistics and Probability Theory, Vienna University of Technology Vienna, Austria
| | - Georg Rath
- MR Centre of Excellence, Medical University of Vienna Vienna, Austria ; Department of Radiodiagnostics and Nuclear Medicine, Medical University of Vienna Vienna, Austria
| | - Andreas Vecsei
- Department of Pediatrics and Adolescent Medicine, St. Anna Children's Hospital, Medical University of Vienna Vienna, Austria
| | - Peter Filzmoser
- Department of Statistics and Probability Theory, Vienna University of Technology Vienna, Austria
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna Vienna, Austria ; MR Centre of Excellence, Medical University of Vienna Vienna, Austria ; Department of Psychiatry, University of Pennsylvania Medical Center Philadelphia, PA, USA
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124
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Chen S, Feng H, Sherchan P, Klebe D, Zhao G, Sun X, Zhang J, Tang J, Zhang JH. Controversies and evolving new mechanisms in subarachnoid hemorrhage. Prog Neurobiol 2014; 115:64-91. [PMID: 24076160 PMCID: PMC3961493 DOI: 10.1016/j.pneurobio.2013.09.002] [Citation(s) in RCA: 270] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/07/2013] [Accepted: 09/12/2013] [Indexed: 12/13/2022]
Abstract
Despite decades of study, subarachnoid hemorrhage (SAH) continues to be a serious and significant health problem in the United States and worldwide. The mechanisms contributing to brain injury after SAH remain unclear. Traditionally, most in vivo research has heavily emphasized the basic mechanisms of SAH over the pathophysiological or morphological changes of delayed cerebral vasospasm after SAH. Unfortunately, the results of clinical trials based on this premise have mostly been disappointing, implicating some other pathophysiological factors, independent of vasospasm, as contributors to poor clinical outcomes. Delayed cerebral vasospasm is no longer the only culprit. In this review, we summarize recent data from both experimental and clinical studies of SAH and discuss the vast array of physiological dysfunctions following SAH that ultimately lead to cell death. Based on the progress in neurobiological understanding of SAH, the terms "early brain injury" and "delayed brain injury" are used according to the temporal progression of SAH-induced brain injury. Additionally, a new concept of the vasculo-neuronal-glia triad model for SAH study is highlighted and presents the challenges and opportunities of this model for future SAH applications.
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Affiliation(s)
- Sheng Chen
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Department of Physiology & Pharmacology, Loma Linda University, Loma Linda, CA, USA
| | - Hua Feng
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Prativa Sherchan
- Department of Physiology & Pharmacology, Loma Linda University, Loma Linda, CA, USA
| | - Damon Klebe
- Department of Physiology & Pharmacology, Loma Linda University, Loma Linda, CA, USA
| | - Gang Zhao
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shanxi, China
| | - Xiaochuan Sun
- Department of Neurosurgery, First Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Jianmin Zhang
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jiping Tang
- Department of Physiology & Pharmacology, Loma Linda University, Loma Linda, CA, USA
| | - John H Zhang
- Department of Physiology & Pharmacology, Loma Linda University, Loma Linda, CA, USA; Department of Neurosurgery, Loma Linda University, Loma Linda, CA, USA.
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125
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Muoio V, Persson PB, Sendeski MM. The neurovascular unit - concept review. Acta Physiol (Oxf) 2014; 210:790-8. [PMID: 24629161 DOI: 10.1111/apha.12250] [Citation(s) in RCA: 327] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/01/2013] [Accepted: 01/27/2014] [Indexed: 01/01/2023]
Abstract
The cerebral hyperaemia is one of the fundamental mechanisms for the central nervous system homeostasis. Due also to this mechanism, oxygen and nutrients are maintained in satisfactory levels, through vasodilation and vasoconstriction. The brain hyperaemia, or coupling, is accomplished by a group of cells, closely related to each other; called neurovascular unit (NVU). The neurovascular unit is composed by neurones, astrocytes, endothelial cells of blood-brain barrier (BBB), myocytes, pericytes and extracellular matrix components. These cells, through their intimate anatomical and chemical relationship, detect the needs of neuronal supply and trigger necessary responses (vasodilation or vasoconstriction) for such demands. Here, we review the concepts of NVU, the coupling mechanisms and research strategies.
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Affiliation(s)
- V. Muoio
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
| | - P. B. Persson
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
| | - M. M. Sendeski
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
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126
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Bicker J, Alves G, Fortuna A, Falcão A. Blood-brain barrier models and their relevance for a successful development of CNS drug delivery systems: a review. Eur J Pharm Biopharm 2014; 87:409-32. [PMID: 24686194 DOI: 10.1016/j.ejpb.2014.03.012] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 03/13/2014] [Accepted: 03/20/2014] [Indexed: 02/05/2023]
Abstract
During the research and development of new drugs directed at the central nervous system, there is a considerable attrition rate caused by their hampered access to the brain by the blood-brain barrier. Throughout the years, several in vitro models have been developed in an attempt to mimic critical functionalities of the blood-brain barrier and reliably predict the permeability of drug candidates. However, the current challenge lies in developing a model that retains fundamental blood-brain barrier characteristics and simultaneously remains compatible with the high throughput demands of pharmaceutical industries. This review firstly describes the roles of all elements of the neurovascular unit and their influence on drug brain penetration. In vitro models, including non-cell based and cell-based models, and in vivo models are herein presented, with a particular emphasis on their methodological aspects. Lastly, their contribution to the improvement of brain drug delivery strategies and drug transport across the blood-brain barrier is also discussed.
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Affiliation(s)
- Joana Bicker
- Laboratory of Pharmacology, University of Coimbra, Coimbra, Portugal; CNC - Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Gilberto Alves
- CNC - Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; CICS-UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal.
| | - Ana Fortuna
- Laboratory of Pharmacology, University of Coimbra, Coimbra, Portugal; CNC - Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Amílcar Falcão
- Laboratory of Pharmacology, University of Coimbra, Coimbra, Portugal; CNC - Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
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Bakker MJ, Hofmann J, Churches OF, Badcock NA, Kohler M, Keage HAD. Cerebrovascular function and cognition in childhood: a systematic review of transcranial Doppler studies. BMC Neurol 2014; 14:43. [PMID: 24602446 PMCID: PMC3975716 DOI: 10.1186/1471-2377-14-43] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 02/26/2014] [Indexed: 11/21/2022] Open
Abstract
Background The contribution of cerebrovascular function to cognitive performance is gaining increased attention. Transcranial doppler (TCD) is portable, reliable, inexpensive and extremely well tolerated by young and clinical samples. It enables measurement of blood flow velocity in major cerebral arteries at rest and during cognitive tasks. Methods We systematically reviewed evidence for associations between cognitive performance and cerebrovascular function in children (0-18 years), as measured using TCD. A total of 2778 articles were retrieved from PsychInfo, Pubmed, and EMBASE searches and 25 relevant articles were identified. Results Most studies investigated clinical groups, where decreased blood flow velocities in infants were associated with poor neurological functioning, and increased blood flow velocities in children with Sickle cell disease were typically associated with cognitive impairment and lower intelligence. Studies were also identified assessing autistic behaviour, mental retardation and sleep disordered breathing. In healthy children, the majority of studies reported cognitive processing produced lateralised changes in blood flow velocities however these physiological responses did not appear to correlate with behavioural cognitive performance. Conclusion Poor cognitive performance appears to be associated with decreased blood flow velocities in premature infants, and increased velocities in Sickle cell disease children using TCD methods. However knowledge in healthy samples is relatively limited. The technique is well tolerated by children, is portable and inexpensive. It therefore stands to make a valuable contribution to knowledge regarding the underlying functional biology of cognitive performance in childhood.
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Affiliation(s)
| | | | | | | | | | - Hannah A D Keage
- Cognitive Neuroscience Laboratory, School of Psychology, Social Work and Social Policy, University of South Australia, GPO BOX 2471, 5001 Adelaide, SA, Australia.
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Subarachnoid Hemorrhage: a Review of Experimental Studies on the Microcirculation and the Neurovascular Unit. Transl Stroke Res 2014; 5:174-89. [DOI: 10.1007/s12975-014-0323-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/20/2013] [Accepted: 01/03/2014] [Indexed: 11/29/2022]
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129
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Michalon A, Bruns A, Risterucci C, Honer M, Ballard TM, Ozmen L, Jaeschke G, Wettstein JG, von Kienlin M, Künnecke B, Lindemann L. Chronic metabotropic glutamate receptor 5 inhibition corrects local alterations of brain activity and improves cognitive performance in fragile X mice. Biol Psychiatry 2014; 75:189-97. [PMID: 23910948 DOI: 10.1016/j.biopsych.2013.05.038] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 05/22/2013] [Accepted: 05/24/2013] [Indexed: 12/28/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) is the most common genetic cause for intellectual disability. Fmr1 knockout (KO) mice are an established model of FXS. Chronic pharmacological inhibition of metabotropic glutamate receptor 5 (mGlu5) in these mice corrects multiple molecular, physiological, and behavioral phenotypes related to patients' symptoms. To better understand the pathophysiology of FXS and the effect of treatment, brain activity was analyzed using functional magnetic resonance imaging in relation to learning and memory performance. METHODS Wild-type (WT) and Fmr1 KO animals receiving chronic treatment with the mGlu5 inhibitor CTEP or vehicle were evaluated consecutively for 1) learning and memory performance in the inhibitory avoidance and extinction test, and 2) for the levels of brain activity using continuous arterial spin labeling based functional magnetic resonance imaging. Neural activity patterns were correlated with cognitive performance using a multivariate regression analysis. Furthermore, mGlu5 receptor expression in brains of untreated mice was analyzed by autoradiography and saturation analysis using [(3)H]-ABP688. RESULTS Chronic CTEP treatment corrected the learning deficit observed in Fmr1 KO mice in the inhibitory avoidance and extinction test and prevented memory extinction in WT and Fmr1 KO animals. Chronic CTEP treatment normalized perfusion in the amygdala and the lateral hypothalamus in Fmr1 KO mice and furthermore decreased perfusion in the hippocampus and increased perfusion in primary sensorimotor cortical areas. No significant differences in mGlu5 receptor expression levels between Fmr1 WT and KO mice were detected. CONCLUSIONS Chronic mGlu5 inhibition corrected the learning deficits and partially normalized the altered brain activity pattern in Fmr1 KO mice.
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Affiliation(s)
- Aubin Michalon
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Andreas Bruns
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Céline Risterucci
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Michael Honer
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Theresa M Ballard
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Laurence Ozmen
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Georg Jaeschke
- Discovery Chemistry, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel; and Neurimmune Holding AG, Schlieren, Switzerland
| | - Joseph G Wettstein
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Markus von Kienlin
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Basil Künnecke
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel
| | - Lothar Lindemann
- Discovery Neuroscience, F. Hoffmann-La Roche AG, Pharma Research & Early Development, Basel.
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130
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Edvinsson L, Larsen SS, Maddahi A, Nielsen J. Plasticity of cerebrovascular smooth muscle cells after subarachnoid hemorrhage. Transl Stroke Res 2014; 5:365-76. [PMID: 24449486 DOI: 10.1007/s12975-014-0331-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/19/2013] [Accepted: 01/06/2014] [Indexed: 12/27/2022]
Abstract
Subarachnoid hemorrhage (SAH) is most often followed by a delayed phase of cerebral ischemia which is associated with high morbidity and mortality rates. The causes underlying this delayed phase are still unsettled, but are believed to include cerebral vasospasm, cortical spreading depression, inflammatory reactions, and microthrombosis. Additionally, a large body of evidence indicates that vascular plasticity plays an important role in SAH pathophysiology, and this review aims to summarize our current knowledge on the phenotypic changes of vascular smooth muscle cells of the cerebral vasculature following SAH. In light of the emerging view that the whole cerebral vasculature and the cells of the brain parenchyma should be viewed as one integrated neurovascular network, phenotypical changes are discussed both for the cerebral arteries and the microvasculature. Furthermore, the intracellular signaling involved in the vascular plasticity is discussed with a focus on the Raf-MEK1/2-ERK1/2 pathway which seems to play a crucial role in SAH pathology.
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Affiliation(s)
- Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Glostrup, Denmark,
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131
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Li N, van Zijl P, Thakor N, Pelled G. Study of the spatial correlation between neuronal activity and BOLD fMRI responses evoked by sensory and channelrhodopsin-2 stimulation in the rat somatosensory cortex. J Mol Neurosci 2014; 53:553-61. [PMID: 24443233 DOI: 10.1007/s12031-013-0221-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 12/22/2013] [Indexed: 12/11/2022]
Abstract
In this work, we combined optogenetic tools with high-resolution blood oxygenation level-dependent functional MRI (BOLD fMRI), electrophysiology, and optical imaging of cerebral blood flow (CBF), to study the spatial correlation between the hemodynamic responses and neuronal activity. We first investigated the spatial and temporal characteristics of BOLD fMRI and the underlying neuronal responses evoked by sensory stimulations at different frequencies. The results demonstrated that under dexmedetomidine anesthesia, BOLD fMRI and neuronal activity in the rat primary somatosensory cortex (S1) have different frequency-dependency and distinct laminar activation profiles. We then found that localized activation of channelrhodopsin-2 (ChR2) expressed in neurons throughout the cortex induced neuronal responses that were confined to the light stimulation S1 region (<500 μm) with distinct laminar activation profile. However, the spatial extent of the hemodynamic responses measured by CBF and BOLD fMRI induced by both ChR2 and sensory stimulation was greater than 3 mm. These results suggest that due to the complex neurovascular coupling, it is challenging to determine specific characteristics of the underlying neuronal activity exclusively from the BOLD fMRI signals.
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Affiliation(s)
- Nan Li
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
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132
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The oxygen paradox of neurovascular coupling. J Cereb Blood Flow Metab 2014; 34:19-29. [PMID: 24149931 PMCID: PMC3887356 DOI: 10.1038/jcbfm.2013.181] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 09/12/2013] [Accepted: 09/22/2013] [Indexed: 01/09/2023]
Abstract
The coupling of cerebral blood flow (CBF) to neuronal activity is well preserved during evolution. Upon changes in the neuronal activity, an incompletely understood coupling mechanism regulates diameter changes of supplying blood vessels, which adjust CBF within seconds. The physiologic brain tissue oxygen content would sustain unimpeded brain function for only 1 second if continuous oxygen supply would suddenly stop. This suggests that the CBF response has evolved to balance oxygen supply and demand. Surprisingly, CBF increases surpass the accompanying increases of cerebral metabolic rate of oxygen (CMRO2). However, a disproportionate CBF increase may be required to increase the concentration gradient from capillary to tissue that drives oxygen delivery. However, the brain tissue oxygen content is not zero, and tissue pO2 decreases could serve to increase oxygen delivery without a CBF increase. Experimental evidence suggests that CMRO2 can increase with constant CBF within limits and decreases of baseline CBF were observed with constant CMRO2. This conflicting evidence may be viewed as an oxygen paradox of neurovascular coupling. As a possible solution for this paradox, we hypothesize that the CBF response has evolved to safeguard brain function in situations of moderate pathophysiological interference with oxygen supply.
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133
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Lacalle-Aurioles M, Alemán-Gómez Y, Guzmán-De-Villoria JA, Cruz-Orduña I, Olazarán J, Mateos-Pérez JM, Martino ME, Desco M. Is the cerebellum the optimal reference region for intensity normalization of perfusion MR studies in early Alzheimer's disease? PLoS One 2013; 8:e81548. [PMID: 24386081 PMCID: PMC3873914 DOI: 10.1371/journal.pone.0081548] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 10/22/2013] [Indexed: 01/08/2023] Open
Abstract
The cerebellum is the region most commonly used as a reference when normalizing the intensity of perfusion images acquired using magnetic resonance imaging (MRI) in Alzheimer's disease (AD) studies. In addition, the cerebellum provides unbiased estimations with nuclear medicine techniques. However, no reports confirm the cerebellum as an optimal reference region in MRI studies or evaluate the consequences of using different normalization regions. In this study, we address the effect of using the cerebellum, whole-brain white matter, and whole-brain cortical gray matter in the normalization of cerebral blood flow (CBF) parametric maps by comparing patients with stable mild cognitive impairment (MCI), patients with AD and healthy controls. According to our results, normalization by whole-brain cortical gray matter enables more sensitive detection of perfusion abnormalities in AD patients and reveals a larger number of affected regions than data normalized by the cerebellum or whole-brain white matter. Therefore, the cerebellum is not the most valid reference region in MRI studies for early stages of AD. After normalization by whole-brain cortical gray matter, we found a significant decrease in CBF in both parietal lobes and an increase in CBF in the right medial temporal lobe. We found no differences in perfusion between patients with stable MCI and healthy controls either before or after normalization.
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Affiliation(s)
- María Lacalle-Aurioles
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Yasser Alemán-Gómez
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | | | - Isabel Cruz-Orduña
- Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - Javier Olazarán
- Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - José María Mateos-Pérez
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | | | - Manuel Desco
- Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
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134
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Haring B, Leng X, Robinson J, Johnson KC, Jackson RD, Beyth R, Wactawski‐Wende J, von Ballmoos MW, Goveas JS, Kuller LH, Wassertheil‐Smoller S. Cardiovascular disease and cognitive decline in postmenopausal women: results from the Women's Health Initiative Memory Study. J Am Heart Assoc 2013; 2:e000369. [PMID: 24351701 PMCID: PMC3886762 DOI: 10.1161/jaha.113.000369] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/24/2013] [Indexed: 12/23/2022]
Abstract
BACKGROUND Data on cardiovascular diseases (CVD) and cognitive decline are conflicting. Our objective was to investigate if CVD is associated with an increased risk for cognitive decline and to examine whether hypertension, diabetes, or adiposity modify the effect of CVD on cognitive functioning. METHODS AND RESULTS Prospective follow-up of 6455 cognitively intact, postmenopausal women aged 65 to 79 years old enrolled in the Women's Health Initiative Memory Study (WHIMS). CVD was determined by self-report. For cognitive decline, we assessed the incidence of mild cognitive impairment (MCI) or probable dementia (PD) via modified mini-mental state examination (3 MS) score, neurocognitive, and neuropsychiatric examinations. The median follow-up was 8.4 years. Women with CVD tended to be at increased risk for cognitive decline compared with those free of CVD (hazard ratio [HR], 1.29; 95% CI: 1.00, 1.67). Women with myocardial infarction or other vascular disease were at highest risk (HR, 2.10; 95% CI: 1.40, 3.15 or HR, 1.97; 95% CI: 1.34, 2.87). Angina pectoris was moderately associated with cognitive decline (HR 1.45; 95% CI: 1.05, 2.01) whereas no significant relationships were found for atrial fibrillation or heart failure. Hypertension and diabetes increased the risk for cognitive decline in women without CVD. Diabetes tended to elevate the risk for MCI/PD in women with CVD. No significant trend was seen for adiposity. CONCLUSIONS CVD is associated with cognitive decline in elderly postmenopausal women. Hypertension and diabetes, but not adiposity, are associated with a higher risk for cognitive decline. More research is warranted on the potential of CVD prevention for preserving cognitive functioning.
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Affiliation(s)
- Bernhard Haring
- Department of Internal Medicine I, Comprehensive Heart Failure Center, University of Würzburg, Würzburg, Bavaria, Germany (B.H.)
| | - Xiaoyan Leng
- Department of Biostatistical Sciences, Wake Forest University Health Sciences, Winston‐Salem, NC (X.L.)
| | - Jennifer Robinson
- Departments of Epidemiology & Medicine, College of Public Health, University of Iowa, IA (J.R.)
| | - Karen C. Johnson
- Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN (K.C.J.)
| | - Rebecca D. Jackson
- Center for Clinical and Translational Science, Division of Endocrinology, Diabetes and Metabolism, The Ohio State University, Columbus, OH (R.D.J.)
| | - Rebecca Beyth
- North Florida/South Georgia Veteran Health System Geriatric Research Education Clinical Center and Division of General Internal Medicine, University of Florida and Malcom Randall VA Medical Center, Gainesville, FL (R.B.)
| | - Jean Wactawski‐Wende
- Department of Social and Preventive Medicine, SUNY School of Public Health and Health Professions, University at Buffalo, Buffalo, NY (J.W.W.)
| | - Moritz Wyler von Ballmoos
- Department of Surgery & Division of Cardiothoracic Surgery, Froedtert Memorial Hospital & Medical College of Wisconsin, Milwaukee, WI (M.W.B.)
| | - Joseph S. Goveas
- Department of Psychiatry and Behavioral Medicine and Institute for Health and Society, Milwaukee, WI (J.S.G.)
| | - Lewis H. Kuller
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA (L.H.K.)
| | - Sylvia Wassertheil‐Smoller
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY (S.W.S.)
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135
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Wu J, He Y, Yang Z, Guo C, Luo Q, Zhou W, Chen S, Li A, Xiong B, Jiang T, Gong H. 3D BrainCV: simultaneous visualization and analysis of cells and capillaries in a whole mouse brain with one-micron voxel resolution. Neuroimage 2013; 87:199-208. [PMID: 24185025 DOI: 10.1016/j.neuroimage.2013.10.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/17/2013] [Accepted: 10/21/2013] [Indexed: 01/07/2023] Open
Abstract
Systematic cellular and vascular configurations are essential for understanding fundamental brain anatomy and metabolism. We demonstrated a 3D brainwide cellular and vascular (called 3D BrainCV) visualization and quantitative protocol for a whole mouse brain. We developed a modified Nissl staining method that quickly labeled the cells and blood vessels simultaneously in an entire mouse brain. Terabytes 3D datasets of the whole mouse brains, with unprecedented details of both individual cells and blood vessels, including capillaries, were simultaneously imaged at 1-μm voxel resolution using micro-optical sectioning tomography (MOST). For quantitative analysis, we proposed an automatic image-processing pipeline to perform brainwide vectorization and analysis of cells and blood vessels. Six representative brain regions from the cortex to the deep, including FrA, M1, PMBSF, V1, striatum, and amygdala, and six parameters, including cell number density, vascular length density, fractional vascular volume, distance from the cells to the nearest microvessel, microvascular length density, and fractional microvascular volume, had been quantitatively analyzed. The results showed that the proximity of cells to blood vessels was linearly correlated with vascular length density, rather than the cell number density. The 3D BrainCV made overall snapshots of the detailed picture of the whole brain architecture, which could be beneficial for the state comparison of the developing and diseased brain.
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Affiliation(s)
- Jingpeng Wu
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yong He
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhongqin Yang
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Congdi Guo
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qingming Luo
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Wei Zhou
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Shangbin Chen
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Anan Li
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Benyi Xiong
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Tao Jiang
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hui Gong
- Britton Chance Center for Biomedical Photonics, Huazhong University of Science and Technology - Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China; MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
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136
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Preferential lentiviral targeting of astrocytes in the central nervous system. PLoS One 2013; 8:e76092. [PMID: 24098426 PMCID: PMC3788778 DOI: 10.1371/journal.pone.0076092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/21/2013] [Indexed: 12/22/2022] Open
Abstract
The ability to visualize and genetically manipulate specific cell populations of the central nervous system (CNS) is fundamental to a better understanding of brain functions at the cellular and molecular levels. Tools to selectively target cells of the CNS include molecular genetics, imaging, and use of transgenic animals. However, these approaches are technically challenging, time consuming, and difficult to control. Viral-mediated targeting of cells in the CNS can be highly beneficial for studying and treating neurodegenerative diseases. Yet, despite specific marking of numerous cell types in the CNS, in vivo selective targeting of astrocytes has not been optimized. In this study, preferential targeting of astrocytes in the CNS was demonstrated using engineered lentiviruses that were pseudotyped with a modified Sindbis envelope and displayed anti-GLAST IgG on their surfaces as an attachment moiety. Viral tropism for astrocytes was initially verified in vitro in primary mixed glia cultures. When injected into the brains of mice, lentiviruses that displayed GLAST IgG on their surface, exhibited preferential astrocyte targeting, compared to pseudotyped lentiviruses that did not incorporate any IgG or that expressed a control isotype IgG. Overall, this approach is highly flexible and can be exploited to selectively target astrocytes or other cell types of the CNS. As such, it can open a window to visualize and genetically manipulate astrocytes or other cells of the CNS as means of research and treatment.
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137
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Krainik A, Villien M, Troprès I, Attyé A, Lamalle L, Bouvier J, Pietras J, Grand S, Le Bas JF, Warnking J. Functional imaging of cerebral perfusion. Diagn Interv Imaging 2013; 94:1259-78. [PMID: 24011870 DOI: 10.1016/j.diii.2013.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.
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Affiliation(s)
- A Krainik
- Clinique universitaire de neuroradiologie et IRM, CHU de Grenoble, CS 10217, 38043 Grenoble cedex, France; Inserm U836, université Joseph-Fourier, site santé, chemin Fortuné-Ferrini, 38706 La Tronche cedex, France; UMS IRMaGe, unité IRM 3T recherche, CHU de Grenoble, CS 10217, 38043 Grenoble cedex 9, France.
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138
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Buxton RB. The physics of functional magnetic resonance imaging (fMRI). REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:096601. [PMID: 24006360 PMCID: PMC4376284 DOI: 10.1088/0034-4885/76/9/096601] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm(3) spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology.
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Affiliation(s)
- Richard B Buxton
- Department of Radiology, University of California, San Diego, USA
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139
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Neurochemical changes within human early blind occipital cortex. Neuroscience 2013; 252:222-33. [PMID: 23954804 DOI: 10.1016/j.neuroscience.2013.08.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 08/01/2013] [Accepted: 08/02/2013] [Indexed: 01/01/2023]
Abstract
Early blindness results in occipital cortex neurons responding to a wide range of auditory and tactile stimuli. These changes in tuning properties are accompanied by an extensive reorganization of the occipital cortex that includes alterations in anatomical structure, neurochemical and metabolic pathways. Although it has been established in animal models that neurochemical pathways are heavily affected by early visual deprivation, the effects of blindness on these pathways in humans is still not well characterized. Here, using (1)H magnetic resonance spectroscopy in nine early blind and normally sighted subjects, we find that early blindness is associated with higher levels of creatine, choline and myo-Inositol and indications of lower levels of GABA within the occipital cortex. These results suggest that the cross-modal responses associated with early blindness may, at least in part, be driven by changes within occipital biochemical pathways.
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140
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Pioglitazone improves reversal learning and exerts mixed cerebrovascular effects in a mouse model of Alzheimer's disease with combined amyloid-β and cerebrovascular pathology. PLoS One 2013; 8:e68612. [PMID: 23874687 PMCID: PMC3715495 DOI: 10.1371/journal.pone.0068612] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/31/2013] [Indexed: 12/14/2022] Open
Abstract
Animal models of Alzheimer's disease (AD) are invaluable in dissecting the pathogenic mechanisms and assessing the efficacy of potential new therapies. Here, we used the peroxisome proliferator-activated receptor gamma agonist pioglitazone in an attempt to rescue the pathogenic phenotype in adult (12 months) and aged (>18 months) bitransgenic A/T mice that overexpress a mutated human amyloid precursor protein (APPSwe,Ind) and a constitutively active form of transforming growth factor-β1 (TGF-β1). A/T mice recapitulate the AD-related cognitive deficits, amyloid beta (Aβ) and cerebrovascular pathologies, as well as the altered metabolic and vascular coupling responses to increased neuronal activity. Pioglitazone normalized neurometabolic and neurovascular coupling responses to sensory stimulation, and reduced cortical astroglial and hippocampal microglial activation in both age groups. Spatial learning and memory deficits in the Morris water maze were not rescued by pioglitazone, but reversal learning was improved in the adult cohort notwithstanding a progressing Aβ pathology. While pioglitazone preserved the constitutive nitric oxide synthesis in the vessel wall, it unexpectedly failed to restore cerebrovascular reactivity in A/T mice and even exacerbated the dilatory deficits. These data demonstrate pioglitazone's efficacy on selective AD hallmarks in a complex AD mouse model of comorbid amyloidosis and cerebrovascular pathology. They further suggest a potential benefit of pioglitazone in managing neuroinflammation, cerebral perfusion and glucose metabolism in AD patients devoid of cerebrovascular pathology.
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141
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Furman JM, Marcus DA, Balaban CD. Vestibular migraine: clinical aspects and pathophysiology. Lancet Neurol 2013; 12:706-15. [DOI: 10.1016/s1474-4422(13)70107-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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142
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Bondke Persson A, Persson PB. On beauty. Acta Physiol (Oxf) 2013; 208:215-7. [PMID: 23614940 DOI: 10.1111/apha.12108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A Bondke Persson
- Institute of Vegetative Physiology, Charité-Universitaetsmedizin Berlin, Berlin, Germany.
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143
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Airan RD, Li N, Gilad AA, Pelled G. Genetic tools to manipulate MRI contrast. NMR IN BIOMEDICINE 2013; 26:803-809. [PMID: 23355411 PMCID: PMC3669659 DOI: 10.1002/nbm.2907] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 11/21/2012] [Indexed: 06/01/2023]
Abstract
Advances in molecular biology in the early 1970s revolutionized research strategies for the study of complex biological processes, which, in turn, created a high demand for new means to visualize these dynamic biological changes noninvasively and in real time. In this respect, MRI was a perfect fit, because of the versatile possibility to alter the different contrast mechanisms. Genetic manipulations are now being translated to MRI through the development of reporters and sensors, as well as the imaging of transgenic and knockout mice. In the past few years, a new molecular biology toolset, namely optogenetics, has emerged, which allows for the manipulation of cellular behavior using light. This technology provides a few particularly attractive features for combination with newly developed MRI techniques for the probing of in vivo cellular and, in particular, neural processes, specifically the ability to control focal, genetically defined cellular populations with high temporal resolution using equipment that is magnetically inert and does not interact with radiofrequency pulses. Recent studies have demonstrated that the combination of optogenetics and functional MRI (fMRI) can provide an appropriate platform to investigate in vivo, at the cellular and molecular levels, the neuronal basis of fMRI signals. In addition, this novel combination of optogenetics with fMRI has the potential to resolve pre-synaptic versus post-synaptic changes in neuronal activity and changes in the activity of large neuronal networks in the context of plasticity associated with development, learning and pathophysiology.
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Affiliation(s)
- Raag D. Airan
- Russell H. Morgan Department of Radiology The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Nan Li
- Russell H. Morgan Department of Radiology The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Assaf A. Gilad
- Russell H. Morgan Department of Radiology The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Galit Pelled
- Russell H. Morgan Department of Radiology The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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Abstract
The term cerebral small vessel disease (SVD) describes a range of neuroimaging, pathological, and associated clinical features. Clinical features range from none, to discrete focal neurological symptoms (eg, stroke), to insidious global neurological dysfunction and dementia. The burden on public health is substantial. The pathogenesis of SVD is largely unknown. Although the pathological processes leading to the arteriolar disease are associated with vascular risk factors and are believed to result from an intrinsic cerebral arteriolar occlusive disease, little is known about how these processes result in brain disease, how SVD lesions contribute to neurological or cognitive symptoms, and the association with risk factors. Pathology often shows end-stage disease, which makes identification of the earliest stages difficult. Neuroimaging provides considerable insights; although the small vessels are not easily seen themselves, the effects of their malfunction on the brain can be tracked with detailed brain imaging. We discuss potential mechanisms, detectable with neuroimaging, that might better fit the available evidence and provide testable hypotheses for future study.
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Affiliation(s)
- Pontus B. Persson
- Institute of Vegetative Physiology; Charité Universitaetsmedizin Berlin; Berlin; Germany
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146
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Dabertrand F, Nelson MT, Brayden JE. Ryanodine receptors, calcium signaling, and regulation of vascular tone in the cerebral parenchymal microcirculation. Microcirculation 2013; 20:307-16. [PMID: 23216877 PMCID: PMC3612564 DOI: 10.1111/micc.12027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 11/21/2012] [Indexed: 11/27/2022]
Abstract
The cerebral blood supply is delivered by a surface network of pial arteries and arterioles from which arise (parenchymal) arterioles that penetrate into the cortex and terminate in a rich capillary bed. The critical regulation of CBF, locally and globally, requires precise vasomotor regulation of the intracerebral microvasculature. This vascular region is anatomically unique as illustrated by the presence of astrocytic processes that envelope almost the entire basolateral surface of PAs. There are, moreover, notable functional differences between pial arteries and PAs. For example, in pial VSMCs, local calcium release events ("calcium sparks") through ryanodine receptor (RyR) channels in SR membrane activate large conductance, calcium-sensitive potassium channels to modulate vascular diameter. In contrast, VSMCs in PAs express functional RyR and BK channels, but under physiological conditions, these channels do not oppose pressure-induced vasoconstriction. Here, we summarize the roles of ryanodine receptors in the parenchymal microvasculature under physiologic and pathologic conditions, and discuss their importance in the control of CBF.
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Affiliation(s)
- Fabrice Dabertrand
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont, USA.
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147
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Age dependence of hemodynamic response characteristics in human functional magnetic resonance imaging. Neurobiol Aging 2013; 34:1469-85. [DOI: 10.1016/j.neurobiolaging.2012.11.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 10/01/2012] [Accepted: 11/02/2012] [Indexed: 01/13/2023]
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148
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Stewart JM, Medow MS, DelPozzi A, Messer ZR, Terilli C, Schwartz CE. Middle cerebral O₂ delivery during the modified Oxford maneuver increases with sodium nitroprusside and decreases during phenylephrine. Am J Physiol Heart Circ Physiol 2013; 304:H1576-83. [PMID: 23564308 DOI: 10.1152/ajpheart.00114.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The modified Oxford maneuver is the reference standard for assessing arterial baroreflex function. The maneuver comprises a systemic bolus injection of 100 μg sodium nitroprusside (SNP) followed by 150 μg phenylephrine (PE). On the one hand, this results in an increase in oxyhemoglobin and total hemoglobin followed by a decrease within the cerebral sample volume illuminated by near-infrared spectroscopy (NIRS). On the other hand, it produces a decrease in cerebral blood flow velocity (CBFv) within the middle cerebral artery (MCA) during SNP and an increase in CBFv during PE as measured by transcranial Doppler ultrasound. To resolve this apparent discrepancy, we hypothesized that SNP dilates, whereas PE constricts, the MCA. We combined transcranial Doppler ultrasound of the right MCA with NIRS illuminating the right frontal cortex in 12 supine healthy subjects 18-24 yr old. Assuming constant O₂ consumption and venous saturation, as estimated by partial venous occlusion plethysmography, we used conservation of mass (continuity) equations to estimate the changes in arterial inflow (ΔQa) and venous outflow (ΔQv) of the NIRS-illuminated area. Oxyhemoglobin and total hemoglobin, respectively, increased by 13.6 ± 1.6 and 15.2 ± 1.4 μmol/kg brain tissue with SNP despite hypotension and decreased by 6 ± 1 and 7 ± 1 μmol/kg with PE despite hypertension. SNP increased ΔQa by 0.36 ± .03 μmol·kg(-1)·s(-1) (21.6 μmol·kg(-1)·min(-1)), whereas CBFv decreased from 71 ± 2 to 62 ± 2 cm/s. PE decreased ΔQa by 0.27 ± .2 μmol·kg(-1)·s(-1) (16.2 μmol·kg(-1)·min(-1)), whereas CBFv increased to 75 ± 3 cm/s. These results are consistent with dilation of the MCA by SNP and constriction by PE.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY, USA.
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149
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The astrocytic contribution to neurovascular coupling – Still more questions than answers? Neurosci Res 2013; 75:171-83. [DOI: 10.1016/j.neures.2013.01.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/15/2012] [Accepted: 12/30/2012] [Indexed: 01/03/2023]
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150
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Tejada J, Costa KM, Bertti P, Garcia-Cairasco N. The epilepsies: complex challenges needing complex solutions. Epilepsy Behav 2013; 26:212-28. [PMID: 23146364 DOI: 10.1016/j.yebeh.2012.09.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 09/16/2012] [Indexed: 12/19/2022]
Abstract
It is widely accepted that epilepsies are complex syndromes due to their multi-factorial origins and manifestations. Different mathematical and computational descriptions use appropriate methods to address nonlinear relationships, chaotic behaviors and emergent properties. These theoretical approaches can be divided into two major categories: descriptive, such as flowcharts, graphs and other statistical analyses, and explicative, which include both realistic and abstract models. Although these modeling tools have brought great advances, a common framework to guide their design, implementation and evaluation, with the goal of future integration, is still needed. In the current review, we discuss two examples of complexity analysis that can be performed with epilepsy data: behavioral sequences of temporal lobe seizures and alterations in an experimental cellular model. We also highlight the importance of the creation of model repositories for the epileptology field and encourage the development of mathematical descriptions of complex systems, together with more accurate simulation techniques.
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Affiliation(s)
- Julián Tejada
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil
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