101
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Shin P, Yoon JH, Jeong Y, Oh WY. High-speed optical coherence tomography angiography for the measurement of stimulus-induced retrograde vasodilation of cerebral pial arteries in awake mice. NEUROPHOTONICS 2020; 7:030502. [PMID: 32923509 PMCID: PMC7481125 DOI: 10.1117/1.nph.7.3.030502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 08/18/2020] [Indexed: 06/01/2023]
Abstract
Significance: Having a clear understanding of functional hyperemia is crucial for functional brain imaging and neurological disease research. Vasodilation induced by sensory stimulus propagates from the arterioles to the upstream pial arteries in a retrograde fashion. As retrograde vasodilation occurs briefly in the early stage of functional hyperemia, an imaging technique with a high temporal resolution is required for its measurement. Aim: We aimed to present an imaging method to measure stimulus-induced retrograde vasodilation in awake animals. Approach: An imaging method based on optical coherence tomography angiography, which enables a high-speed and label-free vessel diameter measurement, was developed and applied for the investigation. Results: The propagation speed of retrograde vasodilation of pial artery was measured in awake mice. Other characteristics of functional hyperemia such as temporal profile and amplitude of the vascular response were also investigated. Conclusions: Our results provide detailed information of stimulus-induced hemodynamic response in the brain of awake mice and suggest the potential utility of our imaging method for the study of functional hyperemia in normal and diseased brain.
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Affiliation(s)
- Paul Shin
- Korea Advanced Institute of Science and Technology, Department of Mechanical Engineering, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
| | - Jin-Hui Yoon
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, Department of Bio and Brain Engineering, Daejeon, Republic of Korea
| | - Yong Jeong
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, Department of Bio and Brain Engineering, Daejeon, Republic of Korea
| | - Wang-Yuhl Oh
- Korea Advanced Institute of Science and Technology, Department of Mechanical Engineering, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
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102
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The capillary Kir channel as sensor and amplifier of neuronal signals: Modeling insights on K +-mediated neurovascular communication. Proc Natl Acad Sci U S A 2020; 117:16626-16637. [PMID: 32601236 DOI: 10.1073/pnas.2000151117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuronal activity leads to an increase in local cerebral blood flow (CBF) to allow adequate supply of oxygen and nutrients to active neurons, a process termed neurovascular coupling (NVC). We have previously shown that capillary endothelial cell (cEC) inwardly rectifying K+ (Kir) channels can sense neuronally evoked increases in interstitial K+ and induce rapid and robust dilations of upstream parenchymal arterioles, suggesting a key role of cECs in NVC. The requirements of this signal conduction remain elusive. Here, we utilize mathematical modeling to investigate how small outward currents in stimulated cECs can elicit physiologically relevant spread of vasodilatory signals within the highly interconnected brain microvascular network to increase local CBF. Our model shows that the Kir channel can act as an "on-off" switch in cECs to hyperpolarize the cell membrane as extracellular K+ increases. A local hyperpolarization can be amplified by the voltage-dependent activation of Kir in neighboring cECs. Sufficient Kir density enables robust amplification of the hyperpolarizing stimulus and produces responses that resemble action potentials in excitable cells. This Kir-mediated excitability can remain localized in the stimulated region or regeneratively propagate over significant distances in the microvascular network, thus dramatically increasing the efficacy of K+ for eliciting local hyperemia. Modeling results show how changes in cEC transmembrane current densities and gap junctional resistances can affect K+-mediated NVC and suggest a key role for Kir as a sensor of neuronal activity and an amplifier of retrograde electrical signaling in the cerebral vasculature.
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103
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Kovacs-Oller T, Ivanova E, Bianchimano P, Sagdullaev BT. The pericyte connectome: spatial precision of neurovascular coupling is driven by selective connectivity maps of pericytes and endothelial cells and is disrupted in diabetes. Cell Discov 2020; 6:39. [PMID: 32566247 PMCID: PMC7296038 DOI: 10.1038/s41421-020-0180-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 05/13/2020] [Indexed: 01/01/2023] Open
Abstract
Functional hyperemia, or the matching of blood flow with activity, directs oxygen and nutrients to regionally firing neurons. The mechanisms responsible for this spatial accuracy remain unclear but are critical for brain function and establish the diagnostic resolution of BOLD-fMRI. Here, we described a mosaic of pericytes, the vasomotor capillary cells in the living retina. We then tested whether this net of pericytes and surrounding neuroglia predicted a connectivity map in response to sensory stimuli. Surprisingly, we found that these connections were not only selective across cell types, but also highly asymmetric spatially. First, pericytes connected predominantly to other neighboring pericytes and endothelial cells, and less to arteriolar smooth muscle cells, and not to surrounding neurons or glia. Second, focal, but not global stimulation evoked a directional vasomotor response by strengthening connections along the feeding vascular branch. This activity required local NO signaling and occurred by means of direct coupling via gap junctions. By contrast, bath application of NO or diabetes, a common microvascular pathology, not only weakened the vascular signaling but also abolished its directionality. We conclude that the exclusivity of neurovascular interactions may thus establish spatial accuracy of blood delivery with the precision of the neuronal receptive field size, and is disrupted early in diabetes.
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Affiliation(s)
- Tamas Kovacs-Oller
- Burke Neurological Institute, White Plains, NY 10605 USA
- Szentagothai Research Centre, University of Pécs, Pécs, H-7624 Hungary
| | - Elena Ivanova
- Burke Neurological Institute, White Plains, NY 10605 USA
| | | | - Botir T. Sagdullaev
- Burke Neurological Institute, White Plains, NY 10605 USA
- Department of Ophthalmology, Weill Cornell Medicine, New York, NY 10065 USA
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104
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Aydin AK, Haselden WD, Goulam Houssen Y, Pouzat C, Rungta RL, Demené C, Tanter M, Drew PJ, Charpak S, Boido D. Transfer functions linking neural calcium to single voxel functional ultrasound signal. Nat Commun 2020; 11:2954. [PMID: 32528069 PMCID: PMC7290037 DOI: 10.1038/s41467-020-16774-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 05/11/2020] [Indexed: 12/13/2022] Open
Abstract
Functional ultrasound imaging (fUS) is an emerging technique that detects changes of cerebral blood volume triggered by brain activation. Here, we investigate the extent to which fUS faithfully reports local neuronal activation by combining fUS and two-photon microscopy (2PM) in a co-registered single voxel brain volume. Using a machine-learning approach, we compute and validate transfer functions between dendritic calcium signals of specific neurons and vascular signals measured at both microscopic (2PM) and mesoscopic (fUS) levels. We find that transfer functions are robust across a wide range of stimulation paradigms and animals, and reveal a second vascular component of neurovascular coupling upon very strong stimulation. We propose that transfer functions can be considered as reliable quantitative reporters to follow neurovascular coupling dynamics. Neurovascular coupling refers to changes in cerebral blood flow in response to neuronal stimulation, but to what extent this change can report neuronal activation is not known. Here the authors develop transfer functions between neural calcium signals and functional ultrasound changes in blood volume in co-registered single voxel brain volumes.
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Affiliation(s)
- Ali-Kemal Aydin
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université de Paris, Paris, France.,INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - William D Haselden
- Medical Scientist Training Program and Neuroscience Graduate Program, The Pennsylvania State University, University Park, PA, USA
| | - Yannick Goulam Houssen
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université de Paris, Paris, France
| | - Christophe Pouzat
- MAP5, Mathématiques Appliquées Paris 5, CNRS UMR 8145, Paris, France
| | - Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université de Paris, Paris, France.,INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - Charlie Demené
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France
| | - Mickael Tanter
- Physics for Medicine, ESPCI, INSERM, CNRS, PSL Research University, Paris, France
| | - Patrick J Drew
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université de Paris, Paris, France. .,INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France.
| | - Davide Boido
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université de Paris, Paris, France. .,NeuroSpin, Bât 145, Commissariat à l'Energie Atomique-Saclay Center, 91191, Gif-sur-Yvette, France.
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105
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Gleichman AJ, Carmichael ST. Glia in neurodegeneration: Drivers of disease or along for the ride? Neurobiol Dis 2020; 142:104957. [PMID: 32512150 DOI: 10.1016/j.nbd.2020.104957] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 05/13/2020] [Accepted: 06/03/2020] [Indexed: 02/08/2023] Open
Abstract
While much of the research on neurodegenerative diseases has focused on neurons, non-neuronal cells are also affected. The extent to which glia and other non-neuronal cells are causally involved in disease pathogenesis versus more passively responding to disease is an area of active research. This is complicated by the fact that there is rarely one known cause of neurodegenerative diseases; rather, these disorders likely involve feedback loops that perpetuate dysfunction. Here, we will review genetic as well as experimental evidence that suggest that non-neuronal cells are at least partially driving disease pathogenesis in numerous neurodegenerative disorders, including Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, Huntington's disease, multiple sclerosis, and Parkinson's disease.
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Affiliation(s)
- Amy J Gleichman
- Department of Neurology, David Geffen School of Medicine, University of California - Los Angeles, Los Angeles, CA 90095, United States.
| | - S Thomas Carmichael
- Department of Neurology, David Geffen School of Medicine, University of California - Los Angeles, Los Angeles, CA 90095, United States
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106
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Negri S, Faris P, Pellavio G, Botta L, Orgiu M, Forcaia G, Sancini G, Laforenza U, Moccia F. Group 1 metabotropic glutamate receptors trigger glutamate-induced intracellular Ca 2+ signals and nitric oxide release in human brain microvascular endothelial cells. Cell Mol Life Sci 2020; 77:2235-2253. [PMID: 31473770 PMCID: PMC11104941 DOI: 10.1007/s00018-019-03284-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/02/2019] [Accepted: 08/16/2019] [Indexed: 12/20/2022]
Abstract
Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity causes an increase in local cerebral blood flow (CBF) to ensure local supply of oxygen and nutrients to the activated areas. The excitatory neurotransmitter glutamate gates post-synaptic N-methyl-D-aspartate receptors to mediate extracellular Ca2+ entry and stimulate neuronal nitric oxide (NO) synthase to release NO, thereby triggering NVC. Recent work suggested that endothelial Ca2+ signals could underpin NVC by recruiting the endothelial NO synthase. For instance, acetylcholine induced intracellular Ca2+ signals followed by NO release by activating muscarinic 5 receptors in hCMEC/D3 cells, a widely employed model of human brain microvascular endothelial cells. Herein, we sought to assess whether also glutamate elicits metabotropic Ca2+ signals and NO release in hCMEC/D3 cells. Glutamate induced a dose-dependent increase in intracellular Ca2+ concentration ([Ca2+]i) that was blocked by α-methyl-4-carboxyphenylglycine and phenocopied by trans-1-amino-1,3-cyclopentanedicarboxylic acid, which, respectively, block and activate group 1 metabotropic glutamate receptors (mGluRs). Accordingly, hCMEC/D3 expressed both mGluR1 and mGluR5 and the Ca2+ response to glutamate was inhibited by their pharmacological blockade with, respectively, CPCCOEt and MTEP hydrochloride. The Ca2+ response to glutamate was initiated by endogenous Ca2+ release from the endoplasmic reticulum and endolysosomal Ca2+ store through inositol-1,4,5-trisphosphate receptors and two-pore channels, respectively, and sustained by store-operated Ca2+ entry. In addition, glutamate induced robust NO release that was suppressed by pharmacological blockade of the accompanying increase in [Ca2+]i. These data demonstrate for the first time that glutamate may induce metabotropic Ca2+ signals in human brain microvascular endothelial cells. The Ca2+ response to glutamate is likely to support NVC during neuronal activity, thereby reinforcing the emerging role of brain microvascular endothelial cells in the regulation of CBF.
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Affiliation(s)
- Sharon Negri
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Pawan Faris
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
- Research Center, Salahaddin University, Erbil, Kurdistan-Region of Iraq, Iraq
| | - Giorgia Pellavio
- Human Physiology Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Matteo Orgiu
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Greta Forcaia
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Giulio Sancini
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Umberto Laforenza
- Human Physiology Unit, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Forlanini 6, 27100, Pavia, Italy.
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107
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Todd N, Angolano C, Ferran C, Devor A, Borsook D, McDannold N. Secondary effects on brain physiology caused by focused ultrasound-mediated disruption of the blood-brain barrier. J Control Release 2020; 324:450-459. [PMID: 32470359 DOI: 10.1016/j.jconrel.2020.05.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 12/12/2022]
Abstract
Focused ultrasound (FUS) combined with microbubbles is a non-invasive method for targeted, reversible disruption of the blood-brain barrier (FUS-BBB opening). This approach holds great promise for improving delivery of therapeutics to the brain. In order to achieve this clinically important goal, the approach necessarily breaks a protective barrier, temporarily, which plays a fundamental role in maintaining a homeostatic environment in the brain. Preclinical and clinical research has identified a set of treatment parameters under which this can be performed safely, whereby the BBB is disrupted to the point of being permeable to normally non-penetrant agents without causing significant acute damage to endothelial or neuronal cells. Much of the early work in this field focused on engineering questions around how to achieve optimal delivery of therapeutics via BBB disruption. However, there is increasing interest in addressing biological questions related to whether and how various aspects of neurophysiology might be affected when this fundamental protective barrier is compromised by the specific mechanisms of FUS-BBB opening. Improving our understanding of these secondary effects is becoming vital now that FUS-BBB opening treatments have entered clinical trials. Such information would help to safely expand FUS-BBB opening protocols into a wider range of drug delivery applications and may even lead to new types of treatments. In this paper, we will critically review our current knowledge of the secondary effects caused by FUS-BBB opening on brain physiology, identify areas that remain understudied, and discuss how a better understanding of these processes can be used to safely advance FUS-BBB opening into a wider range of clinical applications.
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Affiliation(s)
- Nick Todd
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
| | - Cleide Angolano
- Division of Vascular and Endovascular Surgery, Center for Vascular Biology Research, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Christiane Ferran
- Division of Vascular and Endovascular Surgery, Center for Vascular Biology Research, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Anna Devor
- Department of Biomedical Engineering, Boston University, Boston, MA, United States; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - David Borsook
- Center for Pain and the Brain, Boston Children's Hospital, Boston, MA, United States; Department of Anesthesia, Perioperative, and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Nathan McDannold
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
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108
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Xie H, Zhang Q, Zhou N, Li C, Yu K, Liu G, Wu J, Jiang C, Hu R, Wu Y. Environmental enrichment enhances post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional somatosensory cortex. Brain Res Bull 2020; 160:91-97. [PMID: 32388014 DOI: 10.1016/j.brainresbull.2020.04.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 02/27/2020] [Accepted: 04/07/2020] [Indexed: 11/16/2022]
Abstract
Environmental enrichment has been reported to promote functional recovery in an ischemic stroke. However, the underlying mechanism remains unclear. This study aimed to investigate the effect of environmental enrichment treatment on post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional primary somatosensory cortex of rats. With laser speckle imaging, we were able to monitor the resting cerebral blood flow alteration in the middle cerebral artery occlusion model. Both 3- and 28-day post-ischemic infarct volumes were then examined with triphenyltetrazolium chloride and cresyl violet staining, respectively. We found that an exposure to environmental enrichment was associated with higher post-ischemic cerebral blood flow and less brain tissue loss in the ipsilesional primary somatosensory cortex compared with the standard cage environment. Furthermore, environmental enrichment also enhanced the cerebral blood flow response to whisker stimulation in the ipsilesional barrel cortex when measured 28 days after the middle cerebral artery occlusion. Together, the data suggested that an exposure to environmental enrichment promoted the restoration of cerebral blood flow in the ipsilesional cortex and contributed to a better coupling between functional activation and cerebral blood flow change, which might be the possible mechanisms underlying the neuroprotective effects of EE after ischemia.
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Affiliation(s)
- Hongyu Xie
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Qun Zhang
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Naiyun Zhou
- Department of Biomedical Engineering, Stony Brook University, New York, USA
| | - Ce Li
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Kewei Yu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Gang Liu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Junfa Wu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Congyu Jiang
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Ruiping Hu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Yi Wu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
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109
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Royea J, Lacalle-Aurioles M, Trigiani LJ, Fermigier A, Hamel E. AT2R's (Angiotensin II Type 2 Receptor's) Role in Cognitive and Cerebrovascular Deficits in a Mouse Model of Alzheimer Disease. Hypertension 2020; 75:1464-1474. [PMID: 32362228 DOI: 10.1161/hypertensionaha.119.14431] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Antihypertensive medications targeting the renin-angiotensin system have lowered the incidence and progression of Alzheimer disease. Understanding how these medications function could lead to novel therapeutic strategies. AT4Rs (angiotensin IV receptors) have been associated with angiotensin receptor blockers' cognitive, cerebrovascular, and neuroinflammatory rescue in Alzheimer disease models. Yet, whether AT4Rs act alone or with AT2Rs remains unknown. Here, we investigated whether AT2Rs contribute to losartan's benefits and whether chronic AT2R activation could mimic angiotensin receptor blocker benefits in transgenic mice overexpressing familial Alzheimer disease mutations of the human APP (amyloid precursor protein). Losartan-treated mice (10 mg/kg per day, drinking water, 7 months) received intracerebroventricular (1 month) administration of vehicle or AT2R antagonist PD123319 (1.6 nmol/day). PD123319 countered losartan's benefits on spatial learning and memory, neurovascular coupling, and hampered those on oxidative stress and nitric oxide bioavailability. PD123319 did not oppose losartan's benefits on short-term memory and vasodilatory function and had no benefit on neuroinflammation or Aβ (amyloid β) pathology. Mice receiving either vehicle or selective AT2R agonist compound 21 (intracerebroventricular: 1 nmol/day, 1 month or drinking water: 10 mg/kg per day, 7 months), showed no improvement in memory, vasodilatory function, or nitric oxide bioavailability. Compound 21 treatment normalized neurovascular coupling, reduced astrogliosis independent of persisting microgliosis, and exacerbated oxidative stress in APP mice. Compound 21 reduced dense core Aβ plaques, but not diffuse plaques or Aβ species. Our findings suggest that targeting AT2Rs is not an ideal strategy for restoring Aβ-related cognitive and cerebrovascular deficits.
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Affiliation(s)
- Jessika Royea
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Maria Lacalle-Aurioles
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Lianne J Trigiani
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Alice Fermigier
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Edith Hamel
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
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110
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Brezzo G, Simpson J, Ameen-Ali KE, Berwick J, Martin C. Acute effects of systemic inflammation upon the neuro-glial-vascular unit and cerebrovascular function. Brain Behav Immun Health 2020; 5:100074. [PMID: 32685933 PMCID: PMC7357601 DOI: 10.1016/j.bbih.2020.100074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 12/30/2022] Open
Abstract
Brain health relies on a tightly regulated system known as neurovascular coupling whereby the cellular constituents of the neuro-glial-vascular unit (NGVU) regulate cerebral haemodynamics in accordance with brain metabolic demand. Disruption of neurovascular coupling impairs brain health and is associated with the development of a number for neurological conditions, including Alzheimer's disease. The NGVU is also a key site of action for neuroinflammatory responses and contributes to the transition of systemic inflammation to neuroinflammatory processes. Thus, systemic inflammatory challenges may cause a shift in NGVU operation towards prioritising neuroinflammatory action and thus altering neurovascular coupling and resultant cerebrovascular changes. To investigate this, rats were injected with lipopolysaccharide (LPS) (2 mg/kg) to induce a systemic inflammatory response, or vehicle, and brain haemodynamic responses to sensory and non-sensory (hypercapnia) stimuli were assessed in vivo using optical imaging techniques. Following imaging, animals were perfused and their brains extracted to histologically characterise components of the NGVU to determine the association between underlying cellular changes and in vivo blood flow regulation. LPS-treated animals showed changes in haemodynamic function and cerebrovascular dynamics 6 hours after LPS administration. Histological assessment identified a significant increase in astrogliosis, microgliosis and endothelial activation in LPS-treated animals. Our data shows that an acutely induced systemic inflammatory response is able to rapidly alter in vivo haemodynamic function and is associated with significant changes in the cellular constituents of the NGVU. We suggest that these effects are initially mediated by endothelial cells, which are directly exposed to the circulating inflammatory stimulus and have been implicated in regulating functional hyperaemia.
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Affiliation(s)
- Gaia Brezzo
- The University of Sheffield, Department of Psychology, Cathedral Court, 1 Vicar Lane, Sheffield, S1 2LT, UK
| | - Julie Simpson
- The University of Sheffield, Sheffield Institute for Translational Neuroscience (SITraN), 385a Glossop Road, Sheffield, S10 2HQ, UK
| | - Kamar E. Ameen-Ali
- The University of Sheffield, Department of Psychology, Cathedral Court, 1 Vicar Lane, Sheffield, S1 2LT, UK
| | - Jason Berwick
- The University of Sheffield, Department of Psychology, Cathedral Court, 1 Vicar Lane, Sheffield, S1 2LT, UK
| | - Chris Martin
- The University of Sheffield, Department of Psychology, Cathedral Court, 1 Vicar Lane, Sheffield, S1 2LT, UK
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111
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Pradhan S, Banda OA, Farino CJ, Sperduto JL, Keller KA, Taitano R, Slater JH. Biofabrication Strategies and Engineered In Vitro Systems for Vascular Mechanobiology. Adv Healthc Mater 2020; 9:e1901255. [PMID: 32100473 PMCID: PMC8579513 DOI: 10.1002/adhm.201901255] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 01/24/2020] [Indexed: 12/17/2022]
Abstract
The vascular system is integral for maintaining organ-specific functions and homeostasis. Dysregulation in vascular architecture and function can lead to various chronic or acute disorders. Investigation of the role of the vascular system in health and disease has been accelerated through the development of tissue-engineered constructs and microphysiological on-chip platforms. These in vitro systems permit studies of biochemical regulation of vascular networks and parenchymal tissue and provide mechanistic insights into the biophysical and hemodynamic forces acting in organ-specific niches. Detailed understanding of these forces and the mechanotransductory pathways involved is necessary to develop preventative and therapeutic strategies targeting the vascular system. This review describes vascular structure and function, the role of hemodynamic forces in maintaining vascular homeostasis, and measurement approaches for cell and tissue level mechanical properties influencing vascular phenomena. State-of-the-art techniques for fabricating in vitro microvascular systems, with varying degrees of biological and engineering complexity, are summarized. Finally, the role of vascular mechanobiology in organ-specific niches and pathophysiological states, and efforts to recapitulate these events using in vitro microphysiological systems, are explored. It is hoped that this review will help readers appreciate the important, but understudied, role of vascular-parenchymal mechanotransduction in health and disease toward developing mechanotherapeutics for treatment strategies.
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Affiliation(s)
- Shantanu Pradhan
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Omar A. Banda
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
| | - Cindy J. Farino
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
| | - John L. Sperduto
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
| | - Keely A. Keller
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
| | - Ryan Taitano
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
| | - John H. Slater
- Department of Biomedical Engineering, University of Delaware, 150 Academy Street, 161 Colburn Lab, Newark, DE, 19716, USA
- Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, DE 19716, USA
- Delaware Biotechnology Institute, 15 Innovation Way, Newark, DE 19711, USA
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112
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Single-cell RNA sequencing identifies senescent cerebromicrovascular endothelial cells in the aged mouse brain. GeroScience 2020; 42:429-444. [PMID: 32236824 PMCID: PMC7205992 DOI: 10.1007/s11357-020-00177-1] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/01/2020] [Indexed: 01/21/2023] Open
Abstract
Age-related phenotypic changes of cerebromicrovascular endothelial cells lead to dysregulation of cerebral blood flow and blood-brain barrier disruption, promoting the pathogenesis of vascular cognitive impairment (VCI). In recent years, endothelial cell senescence has emerged as a potential mechanism contributing to microvascular pathologies opening the avenue to the therapeutic exploitation of senolytic drugs in preclinical studies. However, difficulties with the detection of senescent endothelial cells in wild type mouse models of aging hinder the assessment of the efficiency of senolytic treatments. To detect senescent endothelial cells in the aging mouse brain, we analyzed 4233 cells in fractions enriched for cerebromicrovascular endothelial cells and other cells associated with the neurovascular unit obtained from young (3-month-old) and aged (28-month-old) C57BL/6 mice. We define 13 transcriptomic cell types by deep, single-cell RNA sequencing. We match transcriptomic signatures of cellular senescence to endothelial cells identified on the basis of their gene expression profile. Our study demonstrates that with advanced aging, there is an increased ratio of senescent endothelial cells (~ 10%) in the mouse cerebral microcirculation. We propose that our single-cell RNA sequencing-based method can be adapted to study the effect of aging on senescence in various brain cell types as well as to evaluate the efficiency of various senolytic regimens in multiple tissues.
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113
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Zechariah A, Tran CHT, Hald BO, Sandow SL, Sancho M, Kim MSM, Fabris S, Tuor UI, Gordon GR, Welsh DG. Intercellular Conduction Optimizes Arterial Network Function and Conserves Blood Flow Homeostasis During Cerebrovascular Challenges. Arterioscler Thromb Vasc Biol 2020; 40:733-750. [PMID: 31826653 PMCID: PMC7058668 DOI: 10.1161/atvbaha.119.313391] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Cerebral arterial networks match blood flow delivery with neural activity. Neurovascular response begins with a stimulus and a focal change in vessel diameter, which by themselves is inconsequential to blood flow magnitude, until they spread and alter the contractile status of neighboring arterial segments. We sought to define the mechanisms underlying integrated vascular behavior and considered the role of intercellular electrical signaling in this phenomenon. Approach and Results: Electron microscopic and histochemical analysis revealed the structural coupling of cerebrovascular cells and the expression of gap junctional subunits at the cell interfaces, enabling intercellular signaling among vascular cells. Indeed, robust vasomotor conduction was detected in human and mice cerebral arteries after focal vessel stimulation: a response attributed to endothelial gap junctional communication, as its genetic alteration attenuated this behavior. Conducted responses were observed to ascend from the penetrating arterioles, influencing the contractile status of cortical surface vessels, in a simulated model of cerebral arterial network. Ascending responses recognized in vivo after whisker stimulation were significantly attenuated in mice with altered endothelial gap junctional signaling confirming that gap junctional communication drives integrated vessel responses. The diminishment in vascular communication also impaired the critical ability of the cerebral vasculature to maintain blood flow homeostasis and hence tissue viability after stroke. CONCLUSIONS Our findings highlight the integral role of intercellular electrical signaling in transcribing focal stimuli into coordinated changes in cerebrovascular contractile activity and expose, a hitherto unknown mechanism for flow regulation after stroke.
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Affiliation(s)
- Anil Zechariah
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Cam Ha T. Tran
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Department of Physiology and Cell Biology, University of Nevada, Reno, Nevada, USA 89557
| | - Bjorn O. Hald
- Department of Neuroscience, Translational Neurobiology, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Shaun L. Sandow
- University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4558 Australia
| | - Maria Sancho
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Michelle Sun Mi Kim
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Sergio Fabris
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Ursula I. Tuor
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Grant R.J. Gordon
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Donald G. Welsh
- Robarts Research Institute and the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5B7
- Hotchkiss Brain Institute, Libin Cardiovascular Institute and the Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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114
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Chow BW, Nuñez V, Kaplan L, Granger AJ, Bistrong K, Zucker HL, Kumar P, Sabatini BL, Gu C. Caveolae in CNS arterioles mediate neurovascular coupling. Nature 2020; 579:106-110. [PMID: 32076269 PMCID: PMC7060132 DOI: 10.1038/s41586-020-2026-1] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 01/03/2020] [Indexed: 12/13/2022]
Abstract
Proper brain function depends on neurovascular coupling: neural activity rapidly increases local blood flow to meet moment-to-moment changes in regional brain energy demand1. Neurovascular coupling is the basis for functional brain imaging2, and its impairment is implicated in neurodegeneration1. The underlying molecular and cellular mechanisms of neurovascular coupling remain poorly understood. The conventional view is that neurons or astrocytes release vasodilatory factors that act directly on smooth muscle cells (SMC) to induce arterial dilation and increase local blood flow1. Here, using two-photon microscopy to image neural activity and vascular dynamics simultaneously in the barrel cortex of awake mice under whisker stimulation, we found that arteriolar endothelial cells (aECs) play an active role in mediating neurovascular coupling. We found that aECs, unlike other vascular segments of ECs in the CNS, have abundant caveolae. Acute genetic perturbations that eliminated caveolae in aECs, but not in neighboring SMCs, impaired neurovascular coupling. Strikingly, caveolae function in aECs is independent of the eNOS-mediated nitric oxide (NO) pathway. Ablation of both caveolae and eNOS completely abolished neurovascular coupling, whereas each single mutant exhibited partial impairment, revealing that caveolae-mediated pathway in aECs is a major contributor to neurovascular coupling. Our findings indicate that vasodilation is largely due to ECs that actively relay signals from the CNS to SMCs via a caveolae-dependent pathway.
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Affiliation(s)
- Brian W Chow
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Vicente Nuñez
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Luke Kaplan
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Adam J Granger
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Karina Bistrong
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Hannah L Zucker
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Payal Kumar
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Bernardo L Sabatini
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Chenghua Gu
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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115
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Moretti R, Caruso P. Small Vessel Disease-Related Dementia: An Invalid Neurovascular Coupling? Int J Mol Sci 2020; 21:E1095. [PMID: 32046035 PMCID: PMC7036993 DOI: 10.3390/ijms21031095] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 02/04/2020] [Accepted: 02/04/2020] [Indexed: 12/18/2022] Open
Abstract
The arteriosclerosis-dependent alteration of brain perfusion is one of the major determinants in small vessel disease, since small vessels have a pivotal role in the brain's autoregulation. Nevertheless, as far as we know, endothelium distress can potentiate the flow dysregulation and lead to subcortical vascular dementia that is related to small vessel disease (SVD), also being defined as subcortical vascular dementia (sVAD), as well as microglia activation, chronic hypoxia and hypoperfusion, vessel-tone dysregulation, altered astrocytes, and pericytes functioning blood-brain barrier disruption. The molecular basis of this pathology remains controversial. The apparent consequence (or a first event, too) is the macroscopic alteration of the neurovascular coupling. Here, we examined the possible mechanisms that lead a healthy aging process towards subcortical dementia. We remarked that SVD and white matter abnormalities related to age could be accelerated and potentiated by different vascular risk factors. Vascular function changes can be heavily influenced by genetic and epigenetic factors, which are, to the best of our knowledge, mostly unknown. Metabolic demands, active neurovascular coupling, correct glymphatic process, and adequate oxidative and inflammatory responses could be bulwarks in defense of the correct aging process; their impairments lead to a potentially catastrophic and non-reversible condition.
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Affiliation(s)
- Rita Moretti
- Neurology Clinic, Department of Medical, Surgical and Health Sciences, University of Trieste, 34149 Trieste, Italy;
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116
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Abstract
The blood-brain barrier (BBB) protects the vertebrate central nervous system from harmful blood-borne, endogenous and exogenous substances to ensure proper neuronal function. The BBB describes a function that is established by endothelial cells of CNS vessels in conjunction with pericytes, astrocytes, neurons and microglia, together forming the neurovascular unit (NVU). Endothelial barrier function is crucially induced and maintained by the Wnt/β-catenin pathway and requires intact NVU for proper functionality. The BBB and the NVU are characterized by a specialized assortment of molecular specializations, providing the basis for tightening, transport and immune response functionality.The present chapter introduces state-of-the-art knowledge of BBB structure and function and highlights current research topics, aiming to understanding in more depth the cellular and molecular interactions at the NVU, determining functionality of the BBB in health and disease, and providing novel potential targets for therapeutic BBB modulation. Moreover, we highlight recent advances in understanding BBB and NVU heterogeneity within the CNS as well as their contribution to CNS physiology, such as neurovascular coupling, and pathophysiology, is discussed. Finally, we give an outlook onto new avenues of BBB research.
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Affiliation(s)
- Fabienne Benz
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefan Liebner
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany.
- Excellence Cluster Cardio Pulmonary System (CPI), Partner Site Frankfurt, Frankfurt, Germany.
- German Center for Cardiovascular Research (DZHK), Partner Site Frankfurt/Mainz, Frankfurt, Germany.
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117
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Abdelkarim D, Zhao Y, Turner MP, Sivakolundu DK, Lu H, Rypma B. A neural-vascular complex of age-related changes in the human brain: Anatomy, physiology, and implications for neurocognitive aging. Neurosci Biobehav Rev 2019; 107:927-944. [DOI: 10.1016/j.neubiorev.2019.09.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 08/02/2019] [Accepted: 09/02/2019] [Indexed: 01/09/2023]
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118
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Royea J, Martinot P, Hamel E. Memory and cerebrovascular deficits recovered following angiotensin IV intervention in a mouse model of Alzheimer's disease. Neurobiol Dis 2019; 134:104644. [PMID: 31669735 DOI: 10.1016/j.nbd.2019.104644] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/01/2019] [Accepted: 10/16/2019] [Indexed: 10/25/2022] Open
Abstract
Angiotensin II type 1 receptor antagonists like losartan have been found to lower the incidence and progression to Alzheimer's disease (AD), as well as rescue cognitive and cerebrovascular deficits in AD mouse models. We previously found that co-administration of an angiotensin IV (AngIV) receptor (AT4R) antagonist prevented losartan's benefits, identifying AT4Rs as a possible target to counter AD pathogenesis. Therein, we investigated whether directly targeting AT4Rs could counter AD pathogenesis in a well-characterized mouse model of AD. Wild-type and human amyloid precursor protein (APP) transgenic (J20 line) mice (4.5 months old) received vehicle or AngIV (~1.3 nmol/day, 1 month) intracerebroventricularly via osmotic minipumps. AngIV restored short-term memory, spatial learning and memory in APP mice. AngIV normalized hippocampal AT4R levels, increased hippocampal subgranular zone cellular proliferation and dendritic arborization, and reduced oxidative stress. AngIV rescued whisker-evoked neurovascular coupling, endothelial- and smooth muscle cell-mediated cerebral vasodilatory responses, and cerebrovascular nitric oxide bioavailability. AngIV did not alter blood pressure, neuroinflammation or amyloid-β (Aβ) pathology. These preclinical findings identify AT4R as a promising target to counter Aβ-related cognitive and cerebrovascular deficits in AD.
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Affiliation(s)
- Jessika Royea
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Pauline Martinot
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada.
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119
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Abstract
Cerebral small vessel disease (SVD) is characterized by changes in the pial and parenchymal microcirculations. SVD produces reductions in cerebral blood flow and impaired blood-brain barrier function, which are leading contributors to age-related reductions in brain health. End-organ effects are diverse, resulting in both cognitive and noncognitive deficits. Underlying phenotypes and mechanisms are multifactorial, with no specific treatments at this time. Despite consequences that are already considerable, the impact of SVD is predicted to increase substantially with the growing aging population. In the face of this health challenge, the basic biology, pathogenesis, and determinants of SVD are poorly defined. This review summarizes recent progress and concepts in this area, highlighting key findings and some major unanswered questions. We focus on phenotypes and mechanisms that underlie microvascular aging, the greatest risk factor for cerebrovascular disease and its subsequent effects.
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Affiliation(s)
- T Michael De Silva
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia;
| | - Frank M Faraci
- Departments of Internal Medicine, Neuroscience, and Pharmacology, Francois M. Abboud Cardiovascular Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA;
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120
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Csiszar A, Yabluchanskiy A, Ungvari A, Ungvari Z, Tarantini S. Overexpression of catalase targeted to mitochondria improves neurovascular coupling responses in aged mice. GeroScience 2019; 41:609-617. [PMID: 31643012 PMCID: PMC6885076 DOI: 10.1007/s11357-019-00111-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 09/20/2019] [Indexed: 12/22/2022] Open
Abstract
Moment-to-moment adjustment of cerebral blood flow (CBF) to neuronal activity via the homeostatic mechanism known as neurovascular coupling (NVC) has an essential role in maintenance of normal brain function. In advanced age cerebromicrovascular endothelial dysfunction impairs NVC responses, which contribute to age-related cognitive decline. Recently, we have shown that pharmacological treatments that attenuate mitochondrial production of reactive oxygen species (ROS) provide significant neurovascular protection, improving NVC responses in aged mice. Transgenic mice that overexpress human catalase localized to the mitochondria (mCAT) are protected from age-related mitochondrial oxidative stress and exhibit a longevity phenotype associated with resistance to several age-related pathologies. The present study was designed to test the hypothesis that mitochondria-targeted overexpression of catalase also confers protection against age-related impairment of NVC responses. To achieve this goal, NVC responses were assessed in aged (24 months old) mCAT mice and compared with those in age-matched wild-type mice and young control mice by measuring CBF responses (laser speckle contrast imaging) evoked by contralateral whisker stimulation. We found that mitochondrial overexpression of catalase resulted in improved NVC in aged mice due to preserved NO-mediated (L-NAME inhibitable) component of the response. Thus, our present and previous findings demonstrate that interventions that boost mitochondrial antioxidative defenses confer significant cerebromicrovascular protective effects, which preserve NVC responses in aged mice. Our findings provide additional proof-of-concept for the potential use of mitochondria-targeted antioxidants as therapy for prevention of vascular cognitive impairment associated with aging.
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Affiliation(s)
- Anna Csiszar
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience, Department of Biochemistry, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Theoretical Medicine Doctoral School, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine, Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary
| | - Andriy Yabluchanskiy
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience, Department of Biochemistry, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Anna Ungvari
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience, Department of Biochemistry, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Zoltan Ungvari
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience, Department of Biochemistry, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine, Institute of Clinical Experimental Research, Semmelweis University, Budapest, Hungary
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine, Department of Public Health, Semmelweis University, Budapest, Hungary
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Stefano Tarantini
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience, Department of Biochemistry, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.
- International Training Program in Geroscience, Theoretical Medicine Doctoral School, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine, Department of Public Health, Semmelweis University, Budapest, Hungary.
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121
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Trigiani LJ, Royea J, Tong XK, Hamel E. Comparative benefits of simvastatin and exercise in a mouse model of vascular cognitive impairment and dementia. FASEB J 2019; 33:13280-13293. [PMID: 31557051 PMCID: PMC6894065 DOI: 10.1096/fj.201901002r] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Aerobic physical exercise (EX) and controlling cardiovascular risk factors in midlife can improve and protect cognitive function in healthy individuals and are considered to be effective at reducing late-onset dementia incidence. By investigating commonalities between these preventative approaches, we sought to identify possible targets for effective interventions. We compared the efficacy of EX and simvastatin (SV) pharmacotherapy to counteract cognitive deficits induced by a high-cholesterol diet (2%, HCD) in mice overexpressing TGF-β1 (TGF mice), a model of vascular cognitive impairment and dementia. Cognitive deficits were found in hypercholesterolemic mice for object recognition memory, and both SV and EX prevented this decline. EX improved stimulus-evoked cerebral blood flow responses and was as effective as SV in normalizing endothelium-dependent vasodilatory responses in cerebral arteries. The up-regulation of galectin-3-positive microglial cells in white matter (WM) of HCD-fed TGF mice with cognitive deficits was significantly reduced by both SV and EX concurrently with cognitive recovery. Altered hippocampal neurogenesis, gray matter astrogliosis, or microgliosis did not correlate with cognitive deficits or benefits. Overall, results indicate that SV and EX prevented cognitive decline in hypercholesterolemic mice and that they share common sites of action in preventing endothelial cell dysfunction and reducing WM inflammation.-Trigiani, L. J., Royea, J., Tong, X.-K., Hamel, E. Comparative benefits of simvastatin and exercise in a mouse model of vascular cognitive impairment and dementia.
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Affiliation(s)
- Lianne J Trigiani
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jessika Royea
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Xin-Kang Tong
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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122
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Sivakolundu DK, West KL, Maruthy GB, Zuppichini M, Turner MP, Abdelkarim D, Zhao Y, Nguyen D, Spence JS, Lu H, Okuda DT, Rypma B. Reduced arterial compliance along the cerebrovascular tree predicts cognitive slowing in multiple sclerosis: Evidence for a neurovascular uncoupling hypothesis. Mult Scler 2019; 26:1486-1496. [PMID: 31373536 DOI: 10.1177/1352458519866605] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Cognitive slowing occurs in ~70% of multiple sclerosis (MS) patients. The pathophysiology of this slowing is unknown. Neurovascular coupling, acute localized blood flow increases following neural activity, is essential for efficient cognition. Loss of vascular compliance along the cerebrovascular tree would result in suboptimal vasodilation, neurovascular uncoupling, and cognitive slowing. OBJECTIVE To assess vascular compliance along the cerebrovascular tree and its relationship to MS-related cognition. METHODS We tested vascular compliance along the cerebrovascular tree by dividing cerebral cortex into nested layers. MS patients and healthy controls were scanned using a dual-echo functional magnetic resonance imaging (fMRI) sequence while they periodically inhaled room air and hypercapnic gas mixture. Cerebrovascular reactivity was calculated from both cerebral blood flow (arterial) and blood-oxygen-level-dependent signal (venous) increases per unit increase in end-tidal CO2. RESULTS Arterial cerebrovascular reactivity changes along the cerebrovascular tree were reduced in cognitively slow MS compared to cognitively normal MS and healthy controls. These changes were fit to exponential functions, the decay constant (arterial compliance index; ACI) of which was associated with individual subjects' reaction time and predicted reaction time after controlling for disease processes. CONCLUSION Such associations suggest prospects for utility of ACI in predicting future cognitive disturbances, monitoring cognitive deficiencies and therapeutic responses, and implicates neurovascular uncoupling as a mechanism of cognitive slowing in MS.
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Affiliation(s)
- Dinesh K Sivakolundu
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Kathryn L West
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Gayathri B Maruthy
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Mark Zuppichini
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Monroe P Turner
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Dema Abdelkarim
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Yuguang Zhao
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Dylan Nguyen
- Neuroinnovation Program, Multiple Sclerosis and Neuroimmunology Imaging Program, Clinical Center for Multiple Sclerosis, Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey S Spence
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
| | - Darin T Okuda
- Neuroinnovation Program, Multiple Sclerosis and Neuroimmunology Imaging Program, Clinical Center for Multiple Sclerosis, Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bart Rypma
- NeuroPsychometric Research Laboratory, Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, TX, USA/Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX, USA
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Bogorad MI, DeStefano JG, Linville RM, Wong AD, Searson PC. Cerebrovascular plasticity: Processes that lead to changes in the architecture of brain microvessels. J Cereb Blood Flow Metab 2019; 39:1413-1432. [PMID: 31208241 PMCID: PMC6681538 DOI: 10.1177/0271678x19855875] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabolic demands of the brain are met by oxygen and glucose, supplied by a complex hierarchical network of microvessels (arterioles, capillaries, and venules). Transient changes in neural activity are accommodated by local dilation of arterioles or capillaries to increase cerebral blood flow and hence nutrient availability. Transport and communication between the circulation and the brain is regulated by the brain microvascular endothelial cells that form the blood-brain barrier. Under homeostatic conditions, there is very little turnover in brain microvascular endothelial cells, and the cerebrovascular architecture is largely static. However, changes in the brain microenvironment, due to environmental factors, disease, or trauma, can result in additive or subtractive changes in cerebrovascular architecture. Additions occur by angiogenesis or vasculogenesis, whereas subtractions occur by vascular pruning, injury, or endothelial cell death. Here we review the various processes that lead to changes in the cerebrovascular architecture, including sustained changes in the brain microenvironment, development and aging, and injury, disease, and repair.
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Affiliation(s)
- Max I Bogorad
- 1 Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,2 Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Jackson G DeStefano
- 1 Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,2 Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Raleigh M Linville
- 1 Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,3 Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Andrew D Wong
- 1 Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,2 Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Peter C Searson
- 1 Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,2 Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA.,3 Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
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124
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Drew PJ. Vascular and neural basis of the BOLD signal. Curr Opin Neurobiol 2019; 58:61-69. [PMID: 31336326 DOI: 10.1016/j.conb.2019.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 06/22/2019] [Indexed: 12/26/2022]
Abstract
Neural activity in the brain is usually coupled to increases in local cerebral blood flow, leading to the increase in oxygenation that generates the BOLD fMRI signal. Recent work has begun to elucidate the vascular and neural mechanisms underlying the BOLD signal. The dilatory response is distributed throughout the vascular network. Arteries actively dilate within a second following neural activity increases, while venous distensions are passive and have a time course that last tens of seconds. Vasodilation, and thus local blood flow, is controlled by the activity of both neurons and astrocytes via multiple different pathways. The relationship between sensory-driven neural activity and the vascular dynamics in sensory areas are well-captured with a linear convolution model. However, depending on the behavioral state or brain region, the coupling between neural activity and hemodynamic signals can be weak or even inverted.
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Affiliation(s)
- Patrick J Drew
- Departments of Engineering Science and Mechanics, Biomedical Engineering and Neurosurgery, Pennsylvania State University, University Park, PA 16802, United States.
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Nizari S, Carare RO, Romero IA, Hawkes CA. 3D Reconstruction of the Neurovascular Unit Reveals Differential Loss of Cholinergic Innervation in the Cortex and Hippocampus of the Adult Mouse Brain. Front Aging Neurosci 2019; 11:172. [PMID: 31333445 PMCID: PMC6620643 DOI: 10.3389/fnagi.2019.00172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/20/2019] [Indexed: 01/02/2023] Open
Abstract
Increasing evidence supports a role for cerebrovasculature dysfunction in the etiology of Alzheimer’s disease (AD). Blood vessels in the brain are composed of a collection of cells and acellular material that comprise the neurovascular unit (NVU). The NVU in the hippocampus and cortex receives innervation from cholinergic neurons that originate in the basal forebrain. Death of these neurons and their nerve fibers is an early feature of AD. However, the effect of the loss of cholinergic innervation on the NVU is not well characterized. The purpose of this study was to evaluate the effect of the loss of cholinergic innervation of components of the NVU at capillaries, arteries and veins in the hippocampus and cortex. Adult male C57BL/6 mice received an intracerebroventricular injection of the immunotoxin p75NTR mu-saporin to induce the loss of cholinergic neurons. Quadruple labeling immunohistochemistry and 3D reconstruction were carried out to characterize specific points of contact between cholinergic fibers and collagen IV, smooth muscle cells and astrocyte endfeet. Innate differences were observed between vessels of the hippocampus and cortex of control mice, including a greater amount of cholinergic contact with perivascular astrocytes in hippocampal capillaries and a thicker basement membrane in hippocampal veins. Saporin treatment induced a loss of cholinergic innervation at the arterial basement membrane and smooth muscle cells of both the hippocampus and the cortex. In the cortex, there was an additional loss of innervation at the astrocytic endfeet. The current results suggest that cortical arteries are more strongly affected by cholinergic denervation than arteries in the hippocampus. This regional variation may have implications for the etiology of the vascular pathology that develops in AD.
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Affiliation(s)
- Shereen Nizari
- School of Life, Health and Chemical Science, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Roxana O Carare
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Ignacio A Romero
- School of Life, Health and Chemical Science, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Cheryl A Hawkes
- School of Life, Health and Chemical Science, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
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126
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Mejía-Rentería H, Matias-Guiu JA, Lauri F, Yus M, Escaned J. Microcirculatory dysfunction in the heart and the brain. Minerva Cardioangiol 2019; 67:318-329. [DOI: 10.23736/s0026-4725.18.04701-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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127
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Lipecz A, Csipo T, Tarantini S, Hand RA, Ngo BTN, Conley S, Nemeth G, Tsorbatzoglou A, Courtney DL, Yabluchanska V, Csiszar A, Ungvari ZI, Yabluchanskiy A. Age-related impairment of neurovascular coupling responses: a dynamic vessel analysis (DVA)-based approach to measure decreased flicker light stimulus-induced retinal arteriolar dilation in healthy older adults. GeroScience 2019; 41:341-349. [PMID: 31209739 DOI: 10.1007/s11357-019-00078-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 06/06/2019] [Indexed: 12/21/2022] Open
Abstract
Aging is a major risk factor for vascular cognitive impairment and dementia (VCID). Recent studies demonstrate that cerebromicrovascular dysfunction plays a causal role in the development of age-related cognitive impairment, in part via disruption of neurovascular coupling (NVC) responses. NVC (functional hyperemia) is responsible for adjusting cerebral blood flow to the increased energetic demands of activated neurons, and in preclinical animal models of aging, pharmacological restoration of NVC is associated with improved cognitive performance. To translate these findings, there is an increasing need to develop novel and sensitive tools to assess cerebromicrovascular function and NVC to assess risk for VCID and evaluate treatment efficacy. Due to shared developmental origins, anatomical features, and physiology, assessment of retinal vessel function may serve as an important surrogate outcome measure to study neurovascular dysfunction. The present study was designed to compare NVC responses in young (< 45 years of age; n = 18) and aged (> 65 years of age; n = 11) healthy human subjects by assessing flicker light-induced changes in the diameter of retinal arterioles using a dynamic vessel analyzer (DVA)-based approach. We found that NVC responses in retinal arterioles were significantly decreased in older adults as compared with younger subjects. We propose that the DVA-based approach can be used to assess NVC, as a surrogate cerebromicrovascular outcome measure, to evaluate the effects of therapeutic interventions in older individuals.
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Affiliation(s)
- Agnes Lipecz
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Department of Ophthalmology, Josa Andras Hospital, Nyiregyhaza, Hungary
| | - Tamas Csipo
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.,Department of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Stefano Tarantini
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Rachel A Hand
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Bich-Thy N Ngo
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Shannon Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Gabor Nemeth
- Department of Ophthalmology, Borsod-Abaúj-Zemplén County Hospital and University Teaching Hospital, Miskolc, Hungary
| | | | - Donald L Courtney
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA
| | - Valeriya Yabluchanska
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Bon Secours St. Francis Family Medicine Center, Midlothian, VA, USA
| | - Anna Csiszar
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Department of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltan I Ungvari
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.,Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary.,Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Andriy Yabluchanskiy
- Translational Geroscience Laboratory, Reynolds Oklahoma Center on Aging/Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 1311, Oklahoma City, OK, 73104, USA.
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128
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Vendel E, Rottschäfer V, de Lange ECM. The need for mathematical modelling of spatial drug distribution within the brain. Fluids Barriers CNS 2019; 16:12. [PMID: 31092261 PMCID: PMC6521438 DOI: 10.1186/s12987-019-0133-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/19/2019] [Indexed: 12/17/2022] Open
Abstract
The blood brain barrier (BBB) is the main barrier that separates the blood from the brain. Because of the BBB, the drug concentration-time profile in the brain may be substantially different from that in the blood. Within the brain, the drug is subject to distributional and elimination processes: diffusion, bulk flow of the brain extracellular fluid (ECF), extra-intracellular exchange, bulk flow of the cerebrospinal fluid (CSF), binding and metabolism. Drug effects are driven by the concentration of a drug at the site of its target and by drug-target interactions. Therefore, a quantitative understanding is needed of the distribution of a drug within the brain in order to predict its effect. Mathematical models can help in the understanding of drug distribution within the brain. The aim of this review is to provide a comprehensive overview of system-specific and drug-specific properties that affect the local distribution of drugs in the brain and of currently existing mathematical models that describe local drug distribution within the brain. Furthermore, we provide an overview on which processes have been addressed in these models and which have not. Altogether, we conclude that there is a need for a more comprehensive and integrated model that fills the current gaps in predicting the local drug distribution within the brain.
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Affiliation(s)
- Esmée Vendel
- Mathematical Institute, Leiden University, Niels Bohrweg 1, 2333CA, Leiden, The Netherlands
| | - Vivi Rottschäfer
- Mathematical Institute, Leiden University, Niels Bohrweg 1, 2333CA, Leiden, The Netherlands
| | - Elizabeth C M de Lange
- Leiden Academic Centre for Drug Research, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
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130
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Endothelial NMDA receptors mediate activity-dependent brain hemodynamic responses in mice. Proc Natl Acad Sci U S A 2019; 116:10229-10231. [PMID: 31061120 PMCID: PMC6535036 DOI: 10.1073/pnas.1902647116] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dynamic coupling of blood supply with energy demand is a natural brain property that requires signaling between synapses and endothelial cells. Our previous work showed that cortical arteriole lumen diameter is regulated by N-methyl-d-aspartate receptors (NMDARs) expressed by brain endothelial cells. The purpose of this study was to determine whether endothelial NMDARs (eNMDARs) regulate functional hyperemia in vivo. In response to whisker stimulation, regional cerebral blood flow (rCBF) and hemodynamic responses were assessed in barrel cortex of awake wild-type or eNMDAR loss-of-function mice using two-photon microscopy. Hyperemic enhancement of rCBF and vasodilation throughout the vascular network was observed in wild-type mice. eNMDAR loss of function reduced hyperemic responses in rCBF and plasma flux in individual vessels. Discovery of an endothelial receptor that regulates brain hyperemia provides insight into how neuronal activity couples with endothelial cells.
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131
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Ostroumova TM, Parfenov VA, Ostroumova OD. Cognitive impairment in patients with arterial hypertension: a relationship with the level and daily blood pressure profile and pathogenetic mechanisms. RATIONAL PHARMACOTHERAPY IN CARDIOLOGY 2019. [DOI: 10.20996/1819-6446-2019-15-2-258-264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- T. M. Ostroumova
- I.M. Sechenov First Moscow State Medical University (Sechenov University)
| | - V. A. Parfenov
- I.M. Sechenov First Moscow State Medical University (Sechenov University)
| | - O. D. Ostroumova
- I.M. Sechenov First Moscow State Medical University (Sechenov University); Russian Clinical and Research Center of Gerontology, Pirogov Russian National Research Medical University
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132
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Turner MP, Hubbard NA, Sivakolundu DK, Himes LM, Hutchison JL, Hart J, Spence JS, Frohman EM, Frohman TC, Okuda DT, Rypma B. Preserved canonicality of the BOLD hemodynamic response reflects healthy cognition: Insights into the healthy brain through the window of Multiple Sclerosis. Neuroimage 2019; 190:46-55. [PMID: 29454932 DOI: 10.1016/j.neuroimage.2017.12.081] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 12/18/2017] [Accepted: 12/22/2017] [Indexed: 10/18/2022] Open
Abstract
The hemodynamic response function (HRF), a model of brain blood-flow changes in response to neural activity, reflects communication between neurons and the vasculature that supplies these neurons in part by means of glial cell intermediaries (e.g., astrocytes). Intact neural-vascular communication might play a central role in optimal cognitive performance. This hypothesis can be tested by comparing healthy individuals to those with known white-matter damage and impaired performance, as seen in Multiple Sclerosis (MS). Glial cell intermediaries facilitate the ability of neurons to adequately convey metabolic needs to cerebral vasculature for sufficient oxygen and nutrient perfusion. In this study, we isolated measurements of the HRF that could quantify the extent to which white-matter affects neural-vascular coupling and cognitive performance. HRFs were modeled from multiple brain regions during multiple cognitive tasks using piecewise cubic spline functions, an approach that minimized assumptions regarding HRF shape that may not be valid for diseased populations, and were characterized using two shape metrics (peak amplitude and time-to-peak). Peak amplitude was reduced, and time-to-peak was longer, in MS patients relative to healthy controls. Faster time-to-peak was predicted by faster reaction time, suggesting an important role for vasodilatory speed in the physiology underlying processing speed. These results support the hypothesis that intact neural-glial-vascular communication underlies optimal neural and cognitive functioning.
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Affiliation(s)
- Monroe P Turner
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Nicholas A Hubbard
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dinesh K Sivakolundu
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Lyndahl M Himes
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Joanna L Hutchison
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - John Hart
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA; Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey S Spence
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Elliot M Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Teresa C Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Darin T Okuda
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bart Rypma
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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133
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Abstract
Vascular theories of migraine and cluster headache have dominated for many years the pathobiological concept of these disorders. This view is supported by observations that trigeminal activation induces a vascular response and that several vasodilating molecules trigger acute attacks of migraine and cluster headache in susceptible individuals. Over the past 30 years, this rationale has been questioned as it became clear that the actions of some of these molecules, in particular, calcitonin gene-related peptide and pituitary adenylate cyclase-activating peptide, extend far beyond the vasoactive effects, as they possess the ability to modulate nociceptive neuronal activity in several key regions of the trigeminovascular system. These findings have shifted our understanding of these disorders to a primarily neuronal origin with the vascular manifestations being the consequence rather than the origin of trigeminal activation. Nevertheless, the neurovascular component, or coupling, seems to be far more complex than initially thought, being involved in several accompanying features. The review will discuss in detail the anatomical basis and the functional role of the neurovascular mechanisms relevant to migraine and cluster headache.
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Affiliation(s)
- Jan Hoffmann
- 1 Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Serapio M Baca
- 2 Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, USA
| | - Simon Akerman
- 3 Department of Neural and Pain Sciences, University of Maryland Baltimore, Baltimore, MD, USA
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134
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Cinciute S. Translating the hemodynamic response: why focused interdisciplinary integration should matter for the future of functional neuroimaging. PeerJ 2019; 7:e6621. [PMID: 30941269 PMCID: PMC6438158 DOI: 10.7717/peerj.6621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/14/2019] [Indexed: 01/28/2023] Open
Abstract
The amount of information acquired with functional neuroimaging techniques, particularly fNIRS and fMRI, is rapidly growing and has enormous potential for studying human brain functioning. Therefore, many scientists focus on solving computational neuroimaging and Big Data issues to advance the discipline. However, the main obstacle—the accurate translation of the hemodynamic response (HR) by the investigation of a physiological phenomenon called neurovascular coupling—is still not fully overcome and, more importantly, often overlooked in this context. This article provides a brief and critical overview of significant findings from cellular biology and in vivo brain physiology with a focus on advancing existing HR modelling paradigms. A brief historical timeline of these disciplines of neuroscience is presented for readers to grasp the concept better, and some possible solutions for further scientific discussion are provided.
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Affiliation(s)
- Sigita Cinciute
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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135
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Mesoscopic and microscopic imaging of sensory responses in the same animal. Nat Commun 2019; 10:1110. [PMID: 30846689 PMCID: PMC6405955 DOI: 10.1038/s41467-019-09082-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/20/2019] [Indexed: 01/09/2023] Open
Abstract
Imaging based on blood flow dynamics is widely used to study sensory processing. Here we investigated the extent to which local neuronal and capillary responses (two-photon microscopy) are correlated to mesoscopic responses detected with fast ultrasound (fUS) and BOLD-fMRI. Using a specialized chronic olfactory bulb preparation, we report that sequential imaging of the same mouse allows quantitative comparison of odour responses, imaged at both microscopic and mesoscopic scales. Under these conditions, functional hyperaemia occurred at the threshold of neuronal activation and fUS-CBV signals could be detected at the level of single voxels with activation maps varying according to blood velocity. Both neuronal and vascular responses increase non-linearly as a function of odour concentration, whereas both microscopic and mesoscopic vascular responses are linearly correlated to local neuronal calcium. These data establish strengths and limits of mesoscopic imaging techniques to report neural activity. Neuronal activity leads to a local increase in blood flow and volume, a process termed hyperaemia. Here, the authors employ multiple imaging approaches of neuronal and vascular activity at varying resolution to delineate the spatiotemporal dynamics of neurovascular coupling evoked by odours in the olfactory bulb.
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136
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Lu L, Hogan-Cann AD, Globa AK, Lu P, Nagy JI, Bamji SX, Anderson CM. Astrocytes drive cortical vasodilatory signaling by activating endothelial NMDA receptors. J Cereb Blood Flow Metab 2019; 39:481-496. [PMID: 29072857 PMCID: PMC6421257 DOI: 10.1177/0271678x17734100] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Astrocytes express neurotransmitter receptors that serve as sensors of synaptic activity and initiate signals leading to activity-dependent local vasodilation and increases in blood flow. We previously showed that arteriolar vasodilation produced by activation of cortical astrocytes is dependent on endothelial nitric oxide synthase (eNOS) and endogenous agonists of N-methyl-D-aspartate (NMDA) receptors. Here, we tested the hypothesis that these effects are mediated by NMDA receptors expressed by brain endothelial cells. Primary endothelial cultures expressed NMDA receptor subunits and produced nitric oxide in response to co-agonists, glutamate and D-serine. In cerebral cortex in situ, immunoelectron microscopy revealed that endothelial cells express the GluN1 NMDA receptor subunit at basolateral membrane surfaces in an orientation suitable for receiving intercellular messengers from brain cells. In cortical slices, activation of astrocytes by two-photon flash photolysis of a caged Ca2+ compound or application of a metabotropic glutamate receptor agonist caused endothelial NO generation and local vasodilation. These effects were mitigated by NMDA receptor antagonists and conditional gene silencing of endothelial GluN1, indicating at least partial dependence on endothelial NMDA receptors. Our observations identify a novel astrocyte-endothelial vasodilatory signaling axis that could contribute to endothelium-dependent vasodilation in brain functional hyperemia.
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Affiliation(s)
- Lingling Lu
- 1 Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba and Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Winnipeg, Canada
| | - Adam D Hogan-Cann
- 1 Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba and Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Winnipeg, Canada
| | - Andrea K Globa
- 2 Department of Cellular and Physiological Sciences and the Djavad Mowafaghian Center for Brain Health, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Ping Lu
- 1 Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba and Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Winnipeg, Canada
| | - James I Nagy
- 3 Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Shernaz X Bamji
- 2 Department of Cellular and Physiological Sciences and the Djavad Mowafaghian Center for Brain Health, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Christopher M Anderson
- 1 Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba and Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Winnipeg, Canada
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137
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How reliable is cerebral blood flow to map changes in neuronal activity? Auton Neurosci 2019; 217:71-79. [PMID: 30744905 DOI: 10.1016/j.autneu.2019.01.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/17/2018] [Accepted: 01/27/2019] [Indexed: 02/06/2023]
Abstract
Neuroimaging techniques, such as functional MRI, map brain activity through hemodynamic-based signals, and are invaluable diagnostic tools in several neurological disorders such as stroke and dementia. Hemodynamic signals are normally precisely related to the underlying neuronal activity through neurovascular coupling mechanisms that ensure the supply of blood, glucose and oxygen to neurons at work. The knowledge of neurovascular coupling has greatly advanced over the last 30 years, it involves multifaceted interactions between excitatory and inhibitory neurons, astrocytes, and the microvessels. While the tight relationship between blood flow and neuronal activity forms a fundamental brain function, whether neurovascular coupling mechanisms are reliable across physiological and pathological conditions has been questioned. In this review, we interrogate the relationship between blood flow and neuronal activity during activation of different brain pathways: a sensory stimulation driven by glutamate, and stimulation of neuromodulatory pathways driven by acetylcholine or noradrenaline, and we compare the underlying neurovascular coupling mechanisms. We further question if neurovascular coupling mechanisms are affected by changing brain states, as seen in behavioral conditions of sleep, wakefulness, attention and in pathological conditions. Finally, we provide a short overview of how alterations of the brain vasculature could compromise the reliability of neurovascular coupling. Overall, while neurovascular coupling requires activation of common signalling pathways, alternate unique cascades exist depending on the activated pathways. Further studies are needed to fully elucidate the alterations in neurovascular coupling across brain states and pathological conditions.
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138
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Hakim MA, Behringer EJ. Simultaneous Measurements of Intracellular Calcium and Membrane Potential in Freshly Isolated and Intact Mouse Cerebral Endothelium. J Vis Exp 2019. [PMID: 30735188 DOI: 10.3791/58832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cerebral arteries and their respective microcirculation deliver oxygen and nutrients to the brain via blood flow regulation. Endothelial cells line the lumen of blood vessels and command changes in vascular diameter as needed to meet the metabolic demand of neurons. Primary endothelial-dependent signaling pathways of hyperpolarization of membrane potential (Vm) and nitric oxide typically operate in parallel to mediate vasodilation and thereby increase blood flow. Although integral to coordinating vasodilation over several millimeters of vascular length, components of endothelium-derived hyperpolarization (EDH) have been historically difficult to measure. These components of EDH entail intracellular Ca2+ [Ca2+]i increases and subsequent activation of small- and intermediate conductance Ca2+-activated K+ (SKCa/IKCa) channels. Here, we present a simplified illustration of the isolation of fresh endothelium from mouse cerebral arteries; simultaneous measurements of endothelial [Ca2+]i and Vm using Fura-2 photometry and intracellular sharp electrodes, respectively; and a continuous superfusion of salt solutions and pharmacological agents under physiological conditions (pH 7.4, 37 °C). Posterior cerebral arteries from the Circle of Willis are removed free of the posterior communicating and the basilar arteries. Enzymatic digestion of cleaned posterior cerebral arterial segments and subsequent trituration facilitates removal of adventitia, perivascular nerves, and smooth muscle cells. Resulting posterior cerebral arterial endothelial "tubes" are then secured under a microscope and examined using a camera, photomultiplier tube, and one to two electrometers while under continuous superfusion. Collectively, this method can simultaneously measure changes in endothelial [Ca2+]i and Vm in discrete cellular locations, in addition to the spreading of EDH through gap junctions up to millimeter distances along the intact endothelium. This method is expected to yield a high-throughput analysis of the cerebral endothelial functions underlying mechanisms of blood flow regulation in the normal and diseased brain.
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Affiliation(s)
- Md A Hakim
- Department of Basic Sciences, Loma Linda University
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139
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Sweeney MD, Zhao Z, Montagne A, Nelson AR, Zlokovic BV. Blood-Brain Barrier: From Physiology to Disease and Back. Physiol Rev 2019; 99:21-78. [PMID: 30280653 PMCID: PMC6335099 DOI: 10.1152/physrev.00050.2017] [Citation(s) in RCA: 1157] [Impact Index Per Article: 231.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 04/17/2018] [Accepted: 04/17/2018] [Indexed: 12/12/2022] Open
Abstract
The blood-brain barrier (BBB) prevents neurotoxic plasma components, blood cells, and pathogens from entering the brain. At the same time, the BBB regulates transport of molecules into and out of the central nervous system (CNS), which maintains tightly controlled chemical composition of the neuronal milieu that is required for proper neuronal functioning. In this review, we first examine molecular and cellular mechanisms underlying the establishment of the BBB. Then, we focus on BBB transport physiology, endothelial and pericyte transporters, and perivascular and paravascular transport. Next, we discuss rare human monogenic neurological disorders with the primary genetic defect in BBB-associated cells demonstrating the link between BBB breakdown and neurodegeneration. Then, we review the effects of genes underlying inheritance and/or increased susceptibility for Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, and amyotrophic lateral sclerosis (ALS) on BBB in relation to other pathologies and neurological deficits. We next examine how BBB dysfunction relates to neurological deficits and other pathologies in the majority of sporadic AD, PD, and ALS cases, multiple sclerosis, other neurodegenerative disorders, and acute CNS disorders such as stroke, traumatic brain injury, spinal cord injury, and epilepsy. Lastly, we discuss BBB-based therapeutic opportunities. We conclude with lessons learned and future directions, with emphasis on technological advances to investigate the BBB functions in the living human brain, and at the molecular and cellular level, and address key unanswered questions.
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Affiliation(s)
- Melanie D Sweeney
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California , Los Angeles, California ; and Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California , Los Angeles, California
| | - Zhen Zhao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California , Los Angeles, California ; and Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California , Los Angeles, California
| | - Axel Montagne
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California , Los Angeles, California ; and Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California , Los Angeles, California
| | - Amy R Nelson
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California , Los Angeles, California ; and Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California , Los Angeles, California
| | - Berislav V Zlokovic
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California , Los Angeles, California ; and Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California , Los Angeles, California
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140
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DeStefano JG, Jamieson JJ, Linville RM, Searson PC. Benchmarking in vitro tissue-engineered blood-brain barrier models. Fluids Barriers CNS 2018; 15:32. [PMID: 30514389 PMCID: PMC6280508 DOI: 10.1186/s12987-018-0117-2] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 11/11/2018] [Indexed: 12/13/2022] Open
Abstract
The blood–brain barrier (BBB) plays a key role in regulating transport into and out of the brain. With increasing interest in the role of the BBB in health and disease, there have been significant advances in the development of in vitro models. The value of these models to the research community is critically dependent on recapitulating characteristics of the BBB in humans or animal models. However, benchmarking in vitro models is surprisingly difficult since much of our knowledge of the structure and function of the BBB comes from in vitro studies. Here we describe a set of parameters that we consider a starting point for benchmarking and validation. These parameters are associated with structure (ultrastructure, wall shear stress, geometry), microenvironment (basement membrane and extracellular matrix), barrier function (transendothelial electrical resistance, permeability, efflux transport), cell function (expression of BBB markers, turnover), and co-culture with other cell types (astrocytes and pericytes). In suggesting benchmarks, we rely primarily on imaging or direct measurements in humans and animal models.
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Affiliation(s)
- Jackson G DeStefano
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - John J Jamieson
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Raleigh M Linville
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peter C Searson
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, USA. .,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA. .,120 Croft Hall, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA.
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141
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Watanabe N, Sasaki S, Masamoto K, Hotta H. Vascular Gap Junctions Contribute to Forepaw Stimulation-Induced Vasodilation Differentially in the Pial and Penetrating Arteries in Isoflurane-Anesthetized Rats. Front Mol Neurosci 2018; 11:446. [PMID: 30559647 PMCID: PMC6286957 DOI: 10.3389/fnmol.2018.00446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/19/2018] [Indexed: 12/25/2022] Open
Abstract
Somatosensory stimulation causes dilation of the pial and penetrating arteries and an increase in cerebral blood flow (CBF) in the representative region of the somatosensory cortex. As an underlying mechanism for such stimulation-induced increases in CBF, cerebral artery dilation has been thought to propagate in the vascular endothelium from the parenchyma to the brain surface. Vascular gap junctions may propagate vasodilation. However, the contribution of vascular gap junctions to cerebrovascular regulation induced by somatosensory stimulation is largely unknown. The aim of the present study was to investigate the contribution of vascular gap junctions to the regulation of the pial and penetrating arteries during neuronal activity attributed to somatosensory stimulation. Experiments were performed on male Wistar rats (age: 7-10 weeks) with artificial ventilation under isoflurane anesthesia. For somatosensory stimulation, the left forepaw was electrically stimulated (1.5 mA, 0.5 ms and 10 Hz, for 5 s). The artery in the forelimb area of the right somatosensory cortex was imaged through a cranial window using a two-photon microscope and the diameter was measured. Carbenoxolone (CBX) was intravenously (i.v.) administered, at a dose of 100 mg/kg, to block vascular gap junctions. The forepaw electrical stimulation increased the diameter of the pial and penetrating arteries by 7.0% and 5.0% of the pre-stimulus diameter, respectively, without changing the arterial pressure. After CBX administration, the change in pial artery diameter during forepaw stimulation was attenuated to 3.2%. However, changes in the penetrating artery were not significantly affected. CBF was measured using a laser speckle flowmeter, together with somatosensory-evoked potential (SEP) recorded in the somatosensory cortex. The extent of CBF increase (by 24.1% of the pre-stimulus level) and amplitude of SEP were not affected by CBX administration. The present results suggest that vascular gap junctions, possibly on the endothelium, contribute to pial artery dilation during neuronal activity induced by somatosensory stimulation.
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Affiliation(s)
- Nobuhiro Watanabe
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Satoshi Sasaki
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Kazuto Masamoto
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan.,Brain Science Inspired Life Support Research Center, The University of Electro-Communications, Tokyo, Japan
| | - Harumi Hotta
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
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142
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Santisteban MM, Iadecola C. Hypertension, dietary salt and cognitive impairment. J Cereb Blood Flow Metab 2018; 38:2112-2128. [PMID: 30295560 PMCID: PMC6282225 DOI: 10.1177/0271678x18803374] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/31/2018] [Indexed: 12/12/2022]
Abstract
Dementia is growing at an alarming rate worldwide. Although Alzheimer disease is the leading cause, over 50% of individuals diagnosed with Alzheimer disease have vascular lesions at autopsy. There has been an increasing appreciation of the pathogenic role of vascular risk factors in cognitive impairment caused by neurodegeneration. Midlife hypertension is a leading risk factor for late-life dementia. Hypertension alters cerebrovascular structure, impairs the major factors regulating the cerebral microcirculation, and promotes Alzheimer pathology. Experimental studies have identified brain perivascular macrophages as the major free radical source mediating neurovascular dysfunction of hypertension. Recent evidence indicates that high dietary salt may also induce cognitive impairment. Contrary to previous belief, the effect is not necessarily associated with hypertension and is mediated by a deficit in endothelial nitric oxide. Collectively, the evidence suggests a remarkable cellular diversity of the impact of vascular risk factors on the cerebral vasculature and cognition. Whereas long-term longitudinal epidemiological studies are needed to resolve the temporal relationships between vascular risk factors and cognitive dysfunction, single-cell molecular studies of the vasculature in animal models will provide a fuller mechanistic understanding. This knowledge is critical for developing new preventive, diagnostic, and therapeutic approaches for these devastating diseases of the mind.
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Affiliation(s)
- Monica M Santisteban
- Feil Family Brain and Mind Research Institute Weill Cornell Medicine, New York, NY, USA
| | - Costantino Iadecola
- Feil Family Brain and Mind Research Institute Weill Cornell Medicine, New York, NY, USA
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143
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Slupe AM, Kirsch JR. Effects of anesthesia on cerebral blood flow, metabolism, and neuroprotection. J Cereb Blood Flow Metab 2018; 38:2192-2208. [PMID: 30009645 PMCID: PMC6282215 DOI: 10.1177/0271678x18789273] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 06/11/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022]
Abstract
Administration of anesthetic agents fundamentally shifts the responsibility for maintenance of homeostasis from the patient and their intrinsic physiological regulatory mechanisms to the anesthesiologist. Continuous delivery of oxygen and nutrients to the brain is necessary to prevent irreversible injury and arises from a complex series of regulatory mechanisms that ensure uninterrupted cerebral blood flow. Our understanding of these regulatory mechanisms and the effects of anesthetics on them has been driven by the tireless work of pioneers in the field. It is of paramount importance that the anesthesiologist shares this understanding. Herein, we will review the physiological determinants of cerebral blood flow and how delivery of anesthesia impacts these processes.
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Affiliation(s)
- Andrew M Slupe
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Jeffrey R Kirsch
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, USA
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144
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Masamoto K, Vazquez A. Optical imaging and modulation of neurovascular responses. J Cereb Blood Flow Metab 2018; 38:2057-2072. [PMID: 30334644 PMCID: PMC6282226 DOI: 10.1177/0271678x18803372] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/02/2018] [Indexed: 12/17/2022]
Abstract
The cerebral microvasculature consists of pial vascular networks, parenchymal descending arterioles, ascending venules and parenchymal capillaries. This vascular compartmentalization is vital to precisely deliver blood to balance continuously varying neural demands in multiple brain regions. Optical imaging techniques have facilitated the investigation of dynamic spatial and temporal properties of microvascular functions in real time. Their combination with transgenic animal models encoding specific genetic targets have further strengthened the importance of optical methods for neurovascular research by allowing for the modulation and monitoring of neuro vascular function. Image analysis methods with three-dimensional reconstruction are also helping to understand the complexity of microscopic observations. Here, we review the compartmentalized cerebral microvascular responses to global perturbations as well as regional changes in response to neural activity to highlight the differences in vascular action sites. In addition, microvascular responses elicited by optical modulation of different cell-type targets are summarized with emphasis on variable spatiotemporal dynamics of microvascular responses. Finally, long-term changes in microvascular compartmentalization are discussed to help understand potential relationships between CBF disturbances and the development of neurodegenerative diseases and cognitive decline.
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Affiliation(s)
- Kazuto Masamoto
- Faculty of Informatics and Engineering, University of Electro-Communications, Tokyo, Japan
- Brain Science Inspired Life Support Research Center, University of Electro-Communications, Tokyo, Japan
| | - Alberto Vazquez
- Departments of Radiology and Bioengineering, University of Pittsburgh, PA, USA
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145
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Koide M, Moshkforoush A, Tsoukias NM, Hill-Eubanks DC, Wellman GC, Nelson MT, Dabertrand F. The yin and yang of K V channels in cerebral small vessel pathologies. Microcirculation 2018; 25. [PMID: 29247493 DOI: 10.1111/micc.12436] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 12/08/2017] [Indexed: 12/14/2022]
Abstract
Cerebral SVDs encompass a group of genetic and sporadic pathological processes leading to brain lesions, cognitive decline, and stroke. There is no specific treatment for SVDs, which progress silently for years before becoming clinically symptomatic. Here, we examine parallels in the functional defects of PAs in CADASIL, a monogenic form of SVD, and in response to SAH, a common type of hemorrhagic stroke that also targets the brain microvasculature. Both animal models exhibit dysregulation of the voltage-gated potassium channel, KV 1, in arteriolar myocytes, an impairment that compromises responses to vasoactive stimuli and impacts CBF autoregulation and local dilatory responses to neuronal activity (NVC). However, the extent to which this channelopathy-like defect ultimately contributes to these pathologies is unknown. Combining experimental data with computational modeling, we describe the role of KV 1 channels in the regulation of myocyte membrane potential at rest and during the modest increase in extracellular potassium associated with NVC. We conclude that PA resting membrane potential and myogenic tone depend strongly on KV 1.2/1.5 channel density, and that reciprocal changes in KV channel density in CADASIL and SAH produce opposite effects on extracellular potassium-mediated dilation during NVC.
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Affiliation(s)
- Masayo Koide
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Arash Moshkforoush
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Nikolaos M Tsoukias
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | | | - George C Wellman
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
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146
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Zuccolo E, Kheder DA, Lim D, Perna A, Nezza FD, Botta L, Scarpellino G, Negri S, Martinotti S, Soda T, Forcaia G, Riboni L, Ranzato E, Sancini G, Ambrosone L, D'Angelo E, Guerra G, Moccia F. Glutamate triggers intracellular Ca 2+ oscillations and nitric oxide release by inducing NAADP- and InsP 3 -dependent Ca 2+ release in mouse brain endothelial cells. J Cell Physiol 2018; 234:3538-3554. [PMID: 30451297 DOI: 10.1002/jcp.26953] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/13/2018] [Indexed: 12/13/2022]
Abstract
The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons and presynaptic glial cells within the neurovascular unit. Glutamate does so by causing an increase in intracellular Ca2+ concentration ([Ca2+ ]i ) in the target cells, which activates the Ca2+ /Calmodulin-dependent nitric oxide (NO) synthase to release NO. It is unclear whether brain endothelial cells also sense glutamate through an elevation in [Ca2+ ]i and NO production. The current study assessed whether and how glutamate drives Ca2+ -dependent NO release in bEND5 cells, an established model of brain endothelial cells. We found that glutamate induced a dose-dependent oscillatory increase in [Ca2+ ]i , which was maximally activated at 200 μM and inhibited by α-methyl-4-carboxyphenylglycine, a selective blocker of Group 1 metabotropic glutamate receptors. Glutamate-induced intracellular Ca2+ oscillations were triggered by rhythmic endogenous Ca2+ mobilization and maintained over time by extracellular Ca2+ entry. Pharmacological manipulation revealed that glutamate-induced endogenous Ca2+ release was mediated by InsP3 -sensitive receptors and nicotinic acid adenine dinucleotide phosphate (NAADP) gated two-pore channel 1. Constitutive store-operated Ca2+ entry mediated Ca2+ entry during ongoing Ca2+ oscillations. Finally, glutamate evoked a robust, although delayed increase in NO levels, which was blocked by pharmacologically inhibition of the accompanying intracellular Ca2+ signals. Of note, glutamate induced Ca2+ -dependent NO release also in hCMEC/D3 cells, an established model of human brain microvascular endothelial cells. This investigation demonstrates for the first time that metabotropic glutamate-induced intracellular Ca2+ oscillations and NO release have the potential to impact on neurovascular coupling in the brain.
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Affiliation(s)
- Estella Zuccolo
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Dlzar A Kheder
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy.,Department of Biology, University of Zakho, Duhok, Kurdistan-Region of Iraq
| | - Dmitry Lim
- Department of Pharmaceutical Sciences, University of Eastern Piedmont "Amedeo Avogadro,", Novara, Italy
| | - Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio,", University of Molise, Campobasso, Italy
| | - Francesca Di Nezza
- Department of Bioscience and Territory (DIBT), University of Molise, Contrada Lappone Pesche, Isernia, Italy
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Sharon Negri
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Simona Martinotti
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT), University of Piemonte Orientale, Alessandria, Italy
| | - Teresa Soda
- Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy.,Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Greta Forcaia
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Laura Riboni
- Department of Medical Biotechnology and Translational Medicine, LITA-Segrate, University of Milan, Segrate, Milan, Italy
| | - Elia Ranzato
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT), University of Piemonte Orientale, Alessandria, Italy
| | - Giulio Sancini
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Luigi Ambrosone
- Department of Medicine and Health Sciences "Vincenzo Tiberio,", Centre of Nanomedicine, University of Molise, Campobasso, Italy
| | - Egidio D'Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,Brain Connectivity Center, C. Mondino National Neurological Institute, Pavia, Italy
| | - Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio,", University of Molise, Campobasso, Italy
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
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147
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Trigiani LJ, Royea J, Lacalle-Aurioles M, Tong XK, Hamel E. Pleiotropic Benefits of the Angiotensin Receptor Blocker Candesartan in a Mouse Model of Alzheimer Disease. Hypertension 2018; 72:1217-1226. [DOI: 10.1161/hypertensionaha.118.11775] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Lianne J. Trigiani
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Jessika Royea
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - María Lacalle-Aurioles
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Xin-Kang Tong
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Edith Hamel
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
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148
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Tran CHT, Peringod G, Gordon GR. Astrocytes Integrate Behavioral State and Vascular Signals during Functional Hyperemia. Neuron 2018; 100:1133-1148.e3. [PMID: 30482689 DOI: 10.1016/j.neuron.2018.09.045] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 06/25/2018] [Accepted: 09/24/2018] [Indexed: 01/17/2023]
Abstract
Dynamic changes in astrocyte free Ca2+ regulate synaptic signaling and local blood flow. Although astrocytes are poised to integrate signals from synapses and the vasculature to perform their functional roles, it remains unclear what dictates astrocyte responses during neurovascular coupling under realistic conditions. We examined peri-arteriole and peri-capillary astrocytes in the barrel cortex of active mice in response to sensory stimulation or volitional behaviors. We observed an AMPA and NMDA receptor-dependent elevation in astrocyte endfoot Ca2+ that followed functional hyperemia onset. This delayed astrocyte Ca2+ signal was dependent on the animal's action at the time of measurement as well as a neurovascular pathway that linked to endothelial-derived nitric oxide. A similar elevation in endfoot Ca2+ was evoked using vascular chemogenetics or optogenetics, and opto-stimulated dilation recruited the same nitric oxide pathway as functional hyperemia. These data show that behavioral state and microvasculature influence astrocyte Ca2+ in active mice. VIDEO ABSTRACT.
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Affiliation(s)
- Cam Ha T Tran
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Govind Peringod
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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149
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Rosenblum WI. Endothelium-dependent responses in the microcirculation observed in vivo. Acta Physiol (Oxf) 2018; 224:e13111. [PMID: 29873936 DOI: 10.1111/apha.13111] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/19/2018] [Accepted: 06/04/2018] [Indexed: 12/17/2022]
Abstract
Endothelium-dependent responses were first demonstrated 40 years ago in the aorta. Since then, extensive research has been conducted in vitro using conductance vessels and materials derived from them. However, the microcirculation controls blood flow to vital organs and has been the focus of in vivo studies of endothelium-dependent dilation beginning immediately after the first in vitro report. Initial in vivo studies employed a light/dye technique for selectively damaging the endothelium to unequivocally prove, in vivo, the existence of endothelium-dependent dilation and in the microvasculature. Endothelium-dependent constriction was similarly proven. Endothelium-dependent agonists include acetylcholine (ACh), bradykinin, arachidonic acid, calcium ionophore A-23187, calcitonin gene-related peptide (CGRP), serotonin, histamine and endothelin-1. Normal and disease states have been studied. Endothelial nitric oxide synthase, cyclooxygenase and cytochrome P450 have been shown to generate the mediators of the responses. Some of the key enzyme systems generate reactive oxygen species (ROS) like superoxide which may prevent EDR. However, one ROS, namely H2 O2 , is one of a number of hyperpolarizing factors that cause dilation initiated by endothelium. Depending upon microvascular bed, a single agonist may use different pathways to elicit an endothelium-dependent response. Interpretation of studies using inhibitors of eNOS is complicated by the fact that these inhibitors may also inhibit ATP-sensitive potassium channels. Other in vivo observations of brain arterioles failed to establish nitric oxide as the mediator of responses elicited by CGRP or by ACh and suggest that a nitrosothiol may be a better fit for the latter.
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Affiliation(s)
- W. I. Rosenblum
- Department of Pathology; Icahn School of Medicine at Mt Sinai NYC; New York NY USA
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150
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Zuccolo E, Laforenza U, Negri S, Botta L, Berra-Romani R, Faris P, Scarpellino G, Forcaia G, Pellavio G, Sancini G, Moccia F. Muscarinic M5 receptors trigger acetylcholine-induced Ca 2+ signals and nitric oxide release in human brain microvascular endothelial cells. J Cell Physiol 2018; 234:4540-4562. [PMID: 30191989 DOI: 10.1002/jcp.27234] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022]
Abstract
Basal forebrain neurons control cerebral blood flow (CBF) by releasing acetylcholine (Ach), which binds to endothelial muscarinic receptors to induce nitric (NO) release and vasodilation in intraparenchymal arterioles. Nevertheless, the mechanism whereby Ach stimulates human brain microvascular endothelial cells to produce NO is still unknown. Herein, we sought to assess whether Ach stimulates NO production in a Ca2+ -dependent manner in hCMEC/D3 cells, a widespread model of human brain microvascular endothelial cells. Ach induced a dose-dependent increase in intracellular Ca2+ concentration ([Ca2+ ]i ) that was prevented by the genetic blockade of M5 muscarinic receptors (M5-mAchRs), which was the only mAchR isoform coupled to phospholipase Cβ (PLCβ) present in hCMEC/D3 cells. A comprehensive real-time polymerase chain reaction analysis revealed the expression of the transcripts encoding for type 3 inositol-1,4,5-trisphosphate receptors (InsP3 R3), two-pore channels 1 and 2 (TPC1-2), Stim2, Orai1-3. Pharmacological manipulation showed that the Ca2+ response to Ach was mediated by InsP3 R3, TPC1-2, and store-operated Ca2+ entry (SOCE). Ach-induced NO release, in turn, was inhibited in cells deficient of M5-mAchRs. Likewise, Ach failed to increase NO levels in the presence of l-NAME, a selective NOS inhibitor, or BAPTA, a membrane-permeant intracellular Ca2+ buffer. Moreover, the pharmacological blockade of the Ca2+ response to Ach also inhibited the accompanying NO production. These data demonstrate for the first time that synaptically released Ach may trigger NO release in human brain microvascular endothelial cells by stimulating a Ca2+ signal via M5-mAchRs.
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Affiliation(s)
- Estella Zuccolo
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Umberto Laforenza
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, Italy
| | - Sharon Negri
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Laura Botta
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Pawan Faris
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy.,Department of Biology, College of Science, Salahaddin University, Erbil, Iraq
| | - Giorgia Scarpellino
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Greta Forcaia
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Giorgia Pellavio
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, Italy
| | - Giulio Sancini
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
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