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Nelissen E, Schepers M, Ponsaerts L, Foulquier S, Bronckaers A, Vanmierlo T, Sandner P, Prickaerts J. Soluble guanylyl cyclase: A novel target for the treatment of vascular cognitive impairment? Pharmacol Res 2023; 197:106970. [PMID: 37884069 DOI: 10.1016/j.phrs.2023.106970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 10/28/2023]
Abstract
Vascular cognitive impairment (VCI) describes neurodegenerative disorders characterized by a vascular component. Pathologically, it involves decreased cerebral blood flow (CBF), white matter lesions, endothelial dysfunction, and blood-brain barrier (BBB) impairments. Molecularly, oxidative stress and inflammation are two of the major underlying mechanisms. Nitric oxide (NO) physiologically stimulates soluble guanylate cyclase (sGC) to induce cGMP production. However, under pathological conditions, NO seems to be at the basis of oxidative stress and inflammation, leading to a decrease in sGC activity and expression. The native form of sGC needs a ferrous heme group bound in order to be sensitive to NO (Fe(II)sGC). Oxidation of sGC leads to the conversion of ferrous to ferric heme (Fe(III)sGC) and even heme-loss (apo-sGC). Both Fe(III)sGC and apo-sGC are insensitive to NO, and the enzyme is therefore inactive. sGC activity can be enhanced either by targeting the NO-sensitive native sGC (Fe(II)sGC), or the inactive, oxidized sGC (Fe(III)sGC) and the heme-free apo-sGC. For this purpose, sGC stimulators acting on Fe(II)sGC and sGC activators acting on Fe(III)sGC/apo-sGC have been developed. These sGC agonists have shown their efficacy in cardiovascular diseases by restoring the physiological and protective functions of the NO-sGC-cGMP pathway, including the reduction of oxidative stress and inflammation, and improvement of vascular functioning. Yet, only very little research has been performed within the cerebrovascular system and VCI pathology when focusing on sGC modulation and its potential protective mechanisms on vascular and neural function. Therefore, within this review, the potential of sGC as a target for treating VCI is highlighted.
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Affiliation(s)
- Ellis Nelissen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, the Netherlands.
| | - Melissa Schepers
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, the Netherlands; Neuro-immune connect and repair lab, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium
| | - Laura Ponsaerts
- Neuro-immune connect and repair lab, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium; Department of Cardio & Organ Systems (COS), Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Sébastien Foulquier
- Department of Pharmacology and Toxicology, School for Mental Health and Neuroscience (MHeNS), School for Cardiovascular Diseases (CARIM), Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, the Netherlands
| | - Annelies Bronckaers
- Department of Cardio & Organ Systems (COS), Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Tim Vanmierlo
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, the Netherlands; Neuro-immune connect and repair lab, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium
| | - Peter Sandner
- Bayer AG, Pharmaceuticals R&D, Pharma Research Center, 42113 Wuppertal, Germany; Hannover Medical School, 30625 Hannover, Germany
| | - Jos Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, the Netherlands
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2
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Novorolsky RJ, Kasheke GDS, Hakim A, Foldvari M, Dorighello GG, Sekler I, Vuligonda V, Sanders ME, Renden RB, Wilson JJ, Robertson GS. Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery. Front Cell Neurosci 2023; 17:1226630. [PMID: 37484823 PMCID: PMC10360135 DOI: 10.3389/fncel.2023.1226630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.
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Affiliation(s)
- Robyn J. Novorolsky
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Gracious D. S. Kasheke
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Antoine Hakim
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Marianna Foldvari
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel G. Dorighello
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben Gurion University, Beersheva, Israel
| | | | | | - Robert B. Renden
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, College of Arts and Sciences, Cornell University, Ithaca, NY, United States
| | - George S. Robertson
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Psychiatry, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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3
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Daher A, Payne S. A network-based model of dynamic cerebral autoregulation. Microvasc Res 2023; 147:104503. [PMID: 36773930 DOI: 10.1016/j.mvr.2023.104503] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/21/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023]
Abstract
Cerebrovascular diseases continue to be one of the leading causes of morbidity and mortality in humans. Abnormalities in dynamic cerebral autoregulation (dCA) have been implicated in many of these disease conditions. Accurate models are therefore needed to better understand the complex pathophysiology behind impaired dCA. We thus present here a simple framework for modelling a vessel-driven network model of dCA in the microvasculature, as opposed to the conventional compartmental modelling approach. Network models incorporate the actual connectivity and anatomy of the vasculature, thereby allowing us to include and trace changes in the calibre and morphology of individual vessels, investigate the spatial specificity and heterogeneity of the various control mechanisms to help disentangle their contributions, and link the model parameters to the actual network physiology. The proposed control feedback mechanisms are incorporated at the level of the individual vessel, and the dynamic pressure and flow fields are solved for here within a simple vessel network. In response to an upstream pressure drop, the network is found to be able to recover cerebral blood flow (CBF) while exhibiting the characteristic autoregulatory behaviour in terms of changes in vessel calibre and the biphasic flow response. We assess the feasibility of our formulation in larger networks by comparing the simulation results to those obtained using a one-dimensional (1D) model of CBF applied to the same microvasculature network and find that our model results are in very good agreement with the 1D solution, while significantly reducing the computational cost, thus enabling more detailed models of network behaviour to be adopted in the future. Accurate and computationally feasible models of dCA that are more representative of the vasculature can help increase the translatability of haemodynamic models into the clinical environment, which would help develop more informed treatment guidelines for patients with cerebrovascular diseases.
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Affiliation(s)
- Ali Daher
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen Payne
- Institute of Applied Mechanics, National Taiwan University, Taiwan
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4
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Cipolla MJ, Alkayed NJ. Vascular Biology of Dementia. Stroke 2023; 54:646-647. [PMID: 36848429 DOI: 10.1161/strokeaha.123.042298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Affiliation(s)
- Marilyn J Cipolla
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington (M.J.C.).,Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington (M.J.C.)
| | - Nabil J Alkayed
- Department of Anesthesiology & Perioperative Medicine and Knight Cardiovascular Institute, Portland, OR (N.J.A.)
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Johnson AC. Hippocampal Vascular Supply and Its Role in Vascular Cognitive Impairment. Stroke 2023; 54:673-685. [PMID: 36848422 PMCID: PMC9991081 DOI: 10.1161/strokeaha.122.038263] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 12/22/2022] [Indexed: 03/01/2023]
Abstract
The incidence of age-related dementia is increasing as the world population ages and due to lack of effective treatments for dementia. Vascular contributions to cognitive impairment and dementia are increasing as the prevalence of pathologies associated with cerebrovascular disease rise, including chronic hypertension, diabetes, and ischemic stroke. The hippocampus is a bilateral deep brain structure that is central to learning, memory, and cognitive function and highly susceptible to hypoxic/ischemic injury. Compared with cortical brain regions such as the somatosensory cortex, less is known about the function of the hippocampal vasculature that is critical in maintaining neurocognitive health. This review focuses on the hippocampal vascular supply, presenting what is known about hippocampal hemodynamics and blood-brain barrier function during health and disease, and discusses evidence that supports its contribution to vascular cognitive impairment and dementia. Understanding vascular-mediated hippocampal injury that contributes to memory dysfunction during healthy aging and cerebrovascular disease is essential to develop effective treatments to slow cognitive decline. The hippocampus and its vasculature may represent one such therapeutic target to mitigate the dementia epidemic.
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Affiliation(s)
- Abbie C Johnson
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington
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Sokolov RA, Jappy D, Podgorny OV, Mukhina IV. Nitric Oxide Synthase Blockade Impairs Spontaneous Calcium Activity in Mouse Primary Hippocampal Culture Cells. Int J Mol Sci 2023; 24:ijms24032608. [PMID: 36768926 PMCID: PMC9917029 DOI: 10.3390/ijms24032608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/17/2023] [Accepted: 01/20/2023] [Indexed: 01/31/2023] Open
Abstract
Oscillation of intracellular calcium concentration is a stable phenomenon that affects cellular function throughout the lifetime of both electrically excitable and non-excitable cells. Nitric oxide, a gaseous secondary messenger and the product of nitric oxide synthase (NOS), affects intracellular calcium dynamics. Using mouse hippocampal primary cultures, we recorded the effect of NOS blockade on neuronal spontaneous calcium activity. There was a correlation between the amplitude of spontaneous calcium events and the number of action potentials (APs) (Spearman R = 0.94). There was a linear rise of DAF-FM fluorescent emission showing an increase in NO concentration with time in neurons (11.9 ± 1.0%). There is correlation between the integral of the signal from DAF-FM and the integral of the spontaneous calcium event signal from Oregon Green 488 (Spearman R = 0.58). Blockade of NOS affected the parameters of the spontaneous calcium events studied (amplitude, frequency, integral, rise slope and decay slope). NOS blockade by Nw-Nitro-L-arginine suppressed the amplitude and frequency of spontaneous calcium events. The NOS blocker 3-Bromo-7-Nitroindazole reduced the frequency but not the amplitude of spontaneous calcium activity. Blockade of the well-known regulator of NOS, calcineurin with cyclosporine A reduced the integral of calcium activity in neurons. The differences and similarities in the effects on the parameters of spontaneous calcium effects caused by different blockades of NO production help to improve understanding of how NO synthesis affects calcium dynamics in neurons.
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Affiliation(s)
- Rostislav A. Sokolov
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia
- Institute of Translational Medicine, Pirogov Russian National Research Medical University, 117513 Moscow, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia
- Correspondence:
| | - David Jappy
- Institute of Fundamental Neurology, Federal Center of Brain Research and Neurotechnologies, Federal Medical Biological Agency, 117997 Moscow, Russia
| | - Oleg V. Podgorny
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia
- Institute of Fundamental Neurology, Federal Center of Brain Research and Neurotechnologies, Federal Medical Biological Agency, 117997 Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117513 Moscow, Russia
| | - Irina V. Mukhina
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia
- Central Research Laboratory, Privolzhsky Research Medical University, 603005 Nizhny Novgorod, Russia
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7
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Soluble guanylate cyclase stimulator riociguat improves spatial memory in mice via peripheral mechanisms. Neurosci Lett 2022; 788:136840. [PMID: 35985509 DOI: 10.1016/j.neulet.2022.136840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/10/2022] [Accepted: 08/11/2022] [Indexed: 01/02/2023]
Abstract
Soluble guanylate cyclase (sGC) - cyclic guanosine monophosphate (cGMP) signalling is important for healthy memory function and a healthy vascular system. Targeting sGC-cGMP signalling can therefore be a potential strategy to enhance memory processes. sGC can be targeted by using agonists, such as sGC stimulator riociguat. Therefore, this study aimed to target sGC using riociguat to investigate its acute effects on memory function and neuronal plasticity in mice. The effects of riociguat on long-term memory and a biperiden-induced memory deficit model for assessing short-term memory were tested in the object location task, and working memory was tested in the Y-maze continuous alternation task. Pharmacokinetic measurements were performed within brain tissue of mice, and hippocampal plasticity measures were assessed using western blotting. Acute oral administration with a low dose of 0.03 mg/kg riociguat was able to enhance working-, short-, and long-term spatial memory. Under cerebral vasoconstriction higher doses of riociguat were still effective on memory. Pharmacokinetic measurements revealed poor brain penetration of riociguat and its metabolite M-1. Increased activation of VASP was found, while no effects were found on other memory-related hippocampal plasticity measures. Memory enhancing effects of riociguat are most likely regulated by vascular peripheral effects on cGMP signalling. Yet, further research is needed to investigate the possible contribution of hemodynamic or metabolic effects of sGC stimulators on memory performance.
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8
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Johnson AC, Uhlig F, Einwag Z, Cataldo N, Erdos B. The neuroendocrine stress response impairs hippocampal vascular function and memory in male and female rats. Neurobiol Dis 2022; 168:105717. [PMID: 35385769 PMCID: PMC9018625 DOI: 10.1016/j.nbd.2022.105717] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/23/2022] [Accepted: 03/29/2022] [Indexed: 11/24/2022] Open
Abstract
Chronic psychological stress affects brain regions involved in memory such as the hippocampus and accelerates age-related cognitive decline, including in Alzheimer's disease and vascular dementia. However, little is known about how chronic stress impacts hippocampal vascular function that is critically involved in maintaining neurocognitive health that could contribute to stress-related memory dysfunction. Here, we used a novel experimental rat model that mimics the neuroendocrine and cardiovascular aspects of chronic stress to determine how the neuroendocrine components of the stress response affect hippocampal function. We studied both male and female rats to determine potential sex differences in the susceptibility of the hippocampus and its vasculature to neuroendocrine stress-induced dysfunction. We show that activation of neuroendocrine stress pathways impaired the vasoreactivity of hippocampal arterioles to mediators involved in coupling neuronal activity with local blood flow that was associated with impaired memory function. Interestingly, we found more hippocampal arteriolar dysfunction and scarcer hippocampal microvasculature in male compared to female rats that was associated with greater memory impairment, suggesting the male sex may be at increased risk of neuroendocrine-derived hippocampal dysfunction during chronic stress. Overall, this study revealed the therapeutic potential of targeting hippocampal arterioles to prevent or slow memory decline in the setting of prolonged and/or unavoidable stress.
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Affiliation(s)
- Abbie C Johnson
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA.
| | - Friederike Uhlig
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Zachary Einwag
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Noelle Cataldo
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Benedek Erdos
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
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9
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Johnson AC, Tremble SM, Cipolla MJ. Experimental Preeclampsia Causes Long-Lasting Hippocampal Vascular Dysfunction and Memory Impairment. Front Physiol 2022; 13:889918. [PMID: 35615682 PMCID: PMC9124928 DOI: 10.3389/fphys.2022.889918] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/22/2022] [Indexed: 11/13/2022] Open
Abstract
Preeclampsia (PE) is a hypertensive disorder of pregnancy that is associated with memory impairment, cognitive decline and brain atrophy later in life in women at ages as young as early-to-mid 40 s. PE increases the risk of vascular dementia three-fold, however, long-lasting effects of PE on the vasculature of vulnerable brain regions involved in memory and cognition, such as the hippocampus, remain unknown. Here, we used a rat model of experimental PE (ePE) induced by maintaining rats on a 2% cholesterol diet beginning on day 7 of gestation to investigate hippocampal function later in life. Hippocampal-dependent memory and hippocampal arteriole (HA) function were determined in Sprague Dawley rats 5 months after either a healthy pregnancy or ePE (n = 8/group). Rats that had ePE were hypertensive and had impaired vasoreactivity of HAs to mediators involved in matching neuronal activity with local blood flow (i.e., neurovascular coupling). ePE rats also had impaired long-term memory, but not spatial memory. Thus, this model of ePE mimics some of the long-lasting cardiovascular and cognitive consequences that occur in women who previously had PE. These findings suggest endothelial and vascular smooth muscle dysfunction of HAs were present months after PE that could impair hippocampal neurovascular coupling. This represents a novel vascular mechanism by which PE causes early-onset dementia.
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Affiliation(s)
- Abbie C. Johnson
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington, VT, United States,*Correspondence: Abbie C. Johnson,
| | - Sarah M. Tremble
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington, VT, United States
| | - Marilyn J. Cipolla
- Department of Neurological Sciences, University of Vermont Larner College of Medicine, Burlington, VT, United States,Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Vermont Larner College of Medicine, Burlington, VT, United States,Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, United States,Department of Electrical and Biomedical Engineering, University of Vermont College of Engineering and Mathematical Sciences, Burlington, VT, United States
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10
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McConnell HL, Mishra A. Cells of the Blood-Brain Barrier: An Overview of the Neurovascular Unit in Health and Disease. Methods Mol Biol 2022; 2492:3-24. [PMID: 35733036 PMCID: PMC9987262 DOI: 10.1007/978-1-0716-2289-6_1] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
The brain is endowed with highly specialized vasculature that is both structurally and functionally unique compared to vasculature supplying peripheral organs. The blood-brain barrier (BBB) is formed by endothelial cells of the cerebral vasculature and prevents extravasation of blood products into the brain to protect neural tissue and maintain a homeostatic environment. The BBB functions as part of the neurovascular unit (NVU), which is composed of neurons, astrocytes, and microglia in addition to the specialized endothelial cells, mural cells, and the basement membrane. Through coordinated intercellular signaling, these cells function as a dynamic unit to tightly regulate brain blood flow, vascular function, neuroimmune responses, and waste clearance. In this chapter, we review the functions of individual NVU components, describe neurovascular coupling as a classic example of NVU function, and discuss archetypal NVU pathophysiology during disease.
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Affiliation(s)
- Heather L McConnell
- Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA
- Office of Academic Development, Houston Methodist Research Institute, Houston, TX, USA
| | - Anusha Mishra
- Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, USA.
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11
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Barzegar M, Stokes KY, Chernyshev O, Kelley RE, Alexander JS. The Role of the ACE2/MasR Axis in Ischemic Stroke: New Insights for Therapy. Biomedicines 2021; 9:1667. [PMID: 34829896 PMCID: PMC8615891 DOI: 10.3390/biomedicines9111667] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/02/2021] [Accepted: 11/08/2021] [Indexed: 12/15/2022] Open
Abstract
Ischemic stroke remains the leading cause of neurologically based morbidity and mortality. Current stroke treatment is limited to two classes of FDA-approved drugs: thrombolytic agents (tissue plasminogen activator (tPA)) and antithrombotic agents (aspirin and heparin), which have a narrow time-window (<4.5 h) for administration after onset of stroke symptoms. While thrombolytic agents restore perfusion, they carry serious risks for hemorrhage, and do not influence damage responses during reperfusion. Consequently, stroke therapies that can suppress deleterious effects of ischemic injury are desperately needed. Angiotensin converting enzyme-2 (ACE2) has been recently suggested to beneficially influence experimental stroke outcomes by converting the vasoconstrictor Ang II into the vasodilator Ang 1-7. In this review, we extensively discuss the protective functions of ACE2-Ang (1-7)-MasR axis of renin angiotensin system (RAS) in ischemic stroke.
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Affiliation(s)
- Mansoureh Barzegar
- Molecular and Cellular Physiology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (M.B.); (K.Y.S.)
| | - Karen Y. Stokes
- Molecular and Cellular Physiology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (M.B.); (K.Y.S.)
| | - Oleg Chernyshev
- Neurology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (O.C.); (R.E.K.)
| | - Roger E. Kelley
- Neurology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (O.C.); (R.E.K.)
| | - Jonathan S. Alexander
- Molecular and Cellular Physiology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (M.B.); (K.Y.S.)
- Neurology, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA; (O.C.); (R.E.K.)
- Medicine, LSU Health Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA
- Oral and Maxillofacial Surgery, Ochsner-LSU Health Sciences Center, Shreveport, LA 71130-3932, USA
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12
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Gonzalez-Fernandez E, Liu Y, Auchus AP, Fan F, Roman RJ. Vascular contributions to cognitive impairment and dementia: the emerging role of 20-HETE. Clin Sci (Lond) 2021; 135:1929-1944. [PMID: 34374423 PMCID: PMC8783562 DOI: 10.1042/cs20201033] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/09/2021] [Accepted: 07/26/2021] [Indexed: 12/13/2022]
Abstract
The accumulation of extracellular amyloid-β (Aβ) and intracellular hyperphosphorylated τ proteins in the brain are the hallmarks of Alzheimer's disease (AD). Much of the research into the pathogenesis of AD has focused on the amyloid or τ hypothesis. These hypotheses propose that Aβ or τ aggregation is the inciting event in AD that leads to downstream neurodegeneration, inflammation, brain atrophy and cognitive impairment. Multiple drugs have been developed and are effective in preventing the accumulation and/or clearing of Aβ or τ proteins. However, clinical trials examining these therapeutic agents have failed to show efficacy in preventing or slowing the progression of the disease. Thus, there is a need for fresh perspectives and the evaluation of alternative therapeutic targets in this field. Epidemiology studies have revealed significant overlap between cardiovascular and cerebrovascular risk factors such as hypertension, diabetes, atherosclerosis and stroke to the development of cognitive impairment. This strong correlation has given birth to a renewed focus on vascular contributions to AD and related dementias. However, few genes and mechanisms have been identified. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoconstrictor that plays a complex role in hypertension, autoregulation of cerebral blood flow and blood-brain barrier (BBB) integrity. Multiple human genome-wide association studies have linked mutations in the cytochrome P450 (CYP) 4A (CYP4A) genes that produce 20-HETE to hypertension and stroke. Most recently, genetic variants in the enzymes that produce 20-HETE have also been linked to AD in human population studies. This review examines the emerging role of 20-HETE in AD and related dementias.
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Affiliation(s)
- Ezekiel Gonzalez-Fernandez
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216
| | - Yedan Liu
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216
| | - Alexander P. Auchus
- Department of Neurology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216
| | - Fan Fan
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216
| | - Richard J. Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216
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13
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Chiba H, Ichikawa-Tomikawa N, Imura T, Sugimoto K. The region-selective regulation of endothelial claudin-5 expression and signaling in brain health and disorders. J Cell Physiol 2021; 236:7134-7143. [PMID: 33694168 DOI: 10.1002/jcp.30357] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/14/2021] [Accepted: 02/25/2021] [Indexed: 12/26/2022]
Abstract
The neurovascular unit (NVU) consists of neurons, glial cells, microvascular cells, and extracellular matrix, and is involved in a variety of physiological and pathological processes in the central nervous system (CNS). Within the NVU, the microvascular endothelial cells and pericytes principally contribute to maintaining the integrity of the blood-brain barrier (BBB). Various types of cells are connected to each other in the NVU by diverse cell adhesion molecules, of which claudin-5 (CLDN5) is by far the most abundantly expressed tight-junction protein in brain microvascular endothelial cells and absolutely required for the maintenance of the BBB. This review highlights recent progress in understanding the region-specific regulation and dysregulation of CLDN5 expression in CNS health and disorders. We also discuss how CLDN5 expression is regionally disrupted within the NVU. In addition, we focus on the link between cell adhesion and transcription factor signalings and describe the possible involvement of CLDN5-adhesion signaling in brain health and disorders.
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Affiliation(s)
- Hideki Chiba
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Naoki Ichikawa-Tomikawa
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Tetsuya Imura
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan.,Department of Surgical Pathology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kotaro Sugimoto
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
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14
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Pfeiffer T, Li Y, Attwell D. Diverse mechanisms regulating brain energy supply at the capillary level. Curr Opin Neurobiol 2021; 69:41-50. [PMID: 33485189 DOI: 10.1016/j.conb.2020.12.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/28/2020] [Accepted: 12/13/2020] [Indexed: 02/06/2023]
Abstract
Neural information processing depends critically on the brain's energy supply, which is provided in the form of glucose and oxygen in the blood. Regulation of this supply occurs by smooth muscle and contractile pericytes adjusting the diameter of arterioles and capillaries, respectively. Controversies exist over the relative importance of capillary and arteriolar level control, whether enzymatically generated signals or K+ ions are the dominant controller of cerebral blood flow, and the involvement of capillary endothelial cells. Here, we try to synthesise the relevant recent data into a coherent view of how brain energy supply is controlled and suggest approaches to answering key questions.
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Affiliation(s)
- Thomas Pfeiffer
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK.
| | - Yuening Li
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK.
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15
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Nizari S, Wells JA, Carare RO, Romero IA, Hawkes CA. Loss of cholinergic innervation differentially affects eNOS-mediated blood flow, drainage of Aβ and cerebral amyloid angiopathy in the cortex and hippocampus of adult mice. Acta Neuropathol Commun 2021; 9:12. [PMID: 33413694 PMCID: PMC7791879 DOI: 10.1186/s40478-020-01108-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/15/2020] [Indexed: 11/18/2022] Open
Abstract
Vascular dysregulation and cholinergic basal forebrain degeneration are both early pathological events in the development of Alzheimer’s disease (AD). Acetylcholine contributes to localised arterial dilatation and increased cerebral blood flow (CBF) during neurovascular coupling via activation of endothelial nitric oxide synthase (eNOS). Decreased vascular reactivity is suggested to contribute to impaired clearance of β-amyloid (Aβ) along intramural periarterial drainage (IPAD) pathways of the brain, leading to the development of cerebral amyloid angiopathy (CAA). However, the possible relationship between loss of cholinergic innervation, impaired vasoreactivity and reduced clearance of Aβ from the brain has not been previously investigated. In the present study, intracerebroventricular administration of mu-saporin resulted in significant death of cholinergic neurons and fibres in the medial septum, cortex and hippocampus of C57BL/6 mice. Arterial spin labelling MRI revealed a loss of CBF response to stimulation of eNOS by the Rho-kinase inhibitor fasudil hydrochloride in the cortex of denervated mice. By contrast, the hippocampus remained responsive to drug treatment, in association with altered eNOS expression. Fasudil hydrochloride significantly increased IPAD in the hippocampus of both control and saporin-treated mice, while increased clearance from the cortex was only observed in control animals. Administration of mu-saporin in the TetOAPPSweInd mouse model of AD was associated with a significant and selective increase in Aβ40-positive CAA. These findings support the importance of the interrelationship between cholinergic innervation and vascular function in the aetiology and/or progression of CAA and suggest that combined eNOS/cholinergic therapies may improve the efficiency of Aβ removal from the brain and reduce its deposition as CAA.
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16
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Ledo A, Lourenço CF, Cadenas E, Barbosa RM, Laranjinha J. The bioactivity of neuronal-derived nitric oxide in aging and neurodegeneration: Switching signaling to degeneration. Free Radic Biol Med 2021; 162:500-513. [PMID: 33186742 DOI: 10.1016/j.freeradbiomed.2020.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 11/02/2020] [Accepted: 11/05/2020] [Indexed: 12/22/2022]
Abstract
The small and diffusible free radical nitric oxide (•NO) has fascinated biological and medical scientists since it was promoted from atmospheric air pollutant to biological ubiquitous signaling molecule. Its unique physical chemical properties expand beyond its radical nature to include fast diffusion in aqueous and lipid environments and selective reactivity in a biological setting determined by bioavailability and reaction rate constants with biomolecules. In the brain, •NO is recognized as a key player in numerous physiological processes ranging from neurotransmission/neuromodulation to neurovascular coupling and immune response. Furthermore, changes in its bioactivity are central to the molecular pathways associated with brain aging and neurodegeneration. The understanding of •NO bioactivity in the brain, however, requires the knowledge of its concentration dynamics with high spatial and temporal resolution upon stimulation of its synthesis. Here we revise our current understanding of the role of neuronal-derived •NO in brain physiology, aging and degeneration, focused on changes in the extracellular concentration dynamics of this free radical and the regulation of bioenergetic metabolism and neurovascular coupling.
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Affiliation(s)
- A Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal; University of Coimbra, Faculty of Pharmacy, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.
| | - C F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal; University of Coimbra, Faculty of Pharmacy, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - E Cadenas
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, 90089, CA, USA
| | - R M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal; University of Coimbra, Faculty of Pharmacy, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
| | - J Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal; University of Coimbra, Faculty of Pharmacy, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal
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17
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Sugimoto K, Ichikawa-Tomikawa N, Nishiura K, Kunii Y, Sano Y, Shimizu F, Kakita A, Kanda T, Imura T, Chiba H. Serotonin/5-HT1A Signaling in the Neurovascular Unit Regulates Endothelial CLDN5 Expression. Int J Mol Sci 2020; 22:ijms22010254. [PMID: 33383868 PMCID: PMC7795278 DOI: 10.3390/ijms22010254] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/23/2020] [Accepted: 12/25/2020] [Indexed: 12/21/2022] Open
Abstract
We previously reported that site-selective claudin-5 (CLDN5) breakdown and protein kinase A (PKA) activation are observed in brain microvessels of schizophrenia, but the underlying molecular basis remains unknown. The 5-HT1 receptors decline the intracellular cAMP levels and inactivate the major downstream PKA, and the 5-HT1A receptor is a promising target for schizophrenia. Therefore, we elucidated the involvement of serotonin/5-HT1A signaling in the endothelial CLDN5 expression. We demonstrate, by immunohistochemistry using post-mortem human brain tissue, that the 5-HT1A receptor is expressed in brain microvascular endothelial cells (BMVECs) and mural cells of the normal prefrontal cortex (PFC) gray matter. We also show that PKA is aberrantly activated not only in BMVECs but also in mural cells of the schizophrenic PFC. We subsequently revealed that the endothelial cell–pericyte tube-like structure was formed in a novel two-dimensional co-culture of human primary BMVECs and a human brain-derived pericyte cell line, in both of which the 5-HT1A receptor was expressed. Furthermore, we disclose that the serotonin/5-HT1A signaling enhances endothelial CLDN5 expression in BMVECs under two-dimensional co-culture conditions. Our findings provide novel insights into the physiological and pathological significance of serotonin/5-HT1A signaling in the region-specific regulation of the blood-brain barrier.
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Affiliation(s)
- Kotaro Sugimoto
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan; (K.S.); (N.I.-T.); (K.N.); (T.I.)
| | - Naoki Ichikawa-Tomikawa
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan; (K.S.); (N.I.-T.); (K.N.); (T.I.)
| | - Keisuke Nishiura
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan; (K.S.); (N.I.-T.); (K.N.); (T.I.)
| | - Yasuto Kunii
- Department of Neuropsychiatry, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan;
| | - Yasuteru Sano
- Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Yamaguchi 755-8505, Japan; (Y.S.); (F.S.); (T.K.)
| | - Fumitaka Shimizu
- Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Yamaguchi 755-8505, Japan; (Y.S.); (F.S.); (T.K.)
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan;
| | - Takashi Kanda
- Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Yamaguchi 755-8505, Japan; (Y.S.); (F.S.); (T.K.)
| | - Tetsuya Imura
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan; (K.S.); (N.I.-T.); (K.N.); (T.I.)
| | - Hideki Chiba
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan; (K.S.); (N.I.-T.); (K.N.); (T.I.)
- Correspondence:
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18
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Erdener ŞE, Dalkara T. Small Vessels Are a Big Problem in Neurodegeneration and Neuroprotection. Front Neurol 2019; 10:889. [PMID: 31474933 PMCID: PMC6707104 DOI: 10.3389/fneur.2019.00889] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
The cerebral microcirculation holds a critical position to match the high metabolic demand by neuronal activity. Functionally, microcirculation is virtually inseparable from other nervous system cells under both physiological and pathological conditions. For successful bench-to-bedside translation of neuroprotection research, the role of microcirculation in acute and chronic neurodegenerative disorders appears to be under-recognized, which may have contributed to clinical trial failures with some neuroprotectants. Increasing data over the last decade suggest that microcirculatory impairments such as endothelial or pericyte dysfunction, morphological irregularities in capillaries or frequent dynamic stalls in blood cell flux resulting in excessive heterogeneity in capillary transit may significantly compromise tissue oxygen availability. We now know that ischemia-induced persistent abnormalities in capillary flow negatively impact restoration of reperfusion after recanalization of occluded cerebral arteries. Similarly, microcirculatory impairments can accompany or even precede neural loss in animal models of several neurodegenerative disorders including Alzheimer's disease. Macrovessels are relatively easy to evaluate with radiological or experimental imaging methods but they cannot faithfully reflect the downstream microcirculatory disturbances, which may be quite heterogeneous across the tissue at microscopic scale and/or happen fast and transiently. The complexity and size of the elements of microcirculation, therefore, require utilization of cutting-edge imaging techniques with high spatiotemporal resolution as well as multidisciplinary team effort to disclose microvascular-neurodegenerative connection and to test treatment approaches to advance the field. Developments in two photon microscopy, ultrafast ultrasound, and optical coherence tomography provide valuable experimental tools to reveal those microscopic events with high resolution. Here, we review the up-to-date advances in understanding of the primary microcirculatory abnormalities that can result in neurodegenerative processes and the combined neurovascular protection approaches that can prevent acute as well as chronic neurodegeneration.
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Affiliation(s)
- Şefik Evren Erdener
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.,Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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19
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Sattiraju A, Mintz A. Pericytes in Glioblastomas: Multifaceted Role Within Tumor Microenvironments and Potential for Therapeutic Interventions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1147:65-91. [PMID: 31147872 DOI: 10.1007/978-3-030-16908-4_2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glioblastoma (GBM) is an aggressive and lethal disease that often results in a poor prognosis. Unlike most solid tumors, GBM is characterized by diffuse infiltrating margins, extensive angiogenesis, hypoxia, necrosis, and clonal heterogeneity. Recurrent disease is an unavoidable consequence for many patients as standard treatment options such as surgery, radiotherapy, and chemotherapy have proven to be insufficient in causing long-term survival benefits. Systemic delivery of promising drugs is hindered due to the blood-brain barrier and non-uniform perfusion within GBM tissue. In recent years, many investigations have highlighted the role of GBM stem cells (GSCs) and their microenvironment in the initiation and maintenance of tumor tissue. Preclinical and early clinical studies to target GSCs and microenvironmental components are currently underway. Of these strategies, immunotherapy using checkpoint inhibitors and redirected cytotoxic T cells have shown promising results in early investigations. But, GBM microenvironment is heterogenous and recent investigations have shown cell populations within this microenvironment to be plastic. These studies underline the importance of identifying the role of and targeting multiple cell populations within the GBM microenvironment which could have a synergistic effect when combined with novel therapies. Pericytes are multipotent perivascular cells that play a vital role within the GBM microenvironment by assisting in tumor initiation, survival, and progression. Due to their role in regulating the blood-brain barrier permeability, promoting angiogenesis, tumor growth, clearing extracellular matrix for infiltrating GBM cells and in helping GBM cells evade immune surveillance, pericytes could be ideal therapeutic targets for stymieing or exploiting their role within the GBM microenvironment. This chapter will introduce hallmarks of GBM and elaborate on the contributions of pericytes to these hallmarks by examining recent findings. In addition, the chapter also highlights the therapeutic value of targeting pericytes, while discussing conventional and novel GBM therapies and obstacles to their efficacy.
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Affiliation(s)
- Anirudh Sattiraju
- Department of Radiology, Columbia University Irving Medical Center, New York, NY, USA
| | - Akiva Mintz
- Department of Radiology, Columbia University Irving Medical Center, New York, NY, USA.
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20
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Duan L, Zhang XD, Miao WY, Sun YJ, Xiong G, Wu Q, Li G, Yang P, Yu H, Li H, Wang Y, Zhang M, Hu LY, Tong X, Zhou WH, Yu X. PDGFRβ Cells Rapidly Relay Inflammatory Signal from the Circulatory System to Neurons via Chemokine CCL2. Neuron 2018; 100:183-200.e8. [PMID: 30269986 DOI: 10.1016/j.neuron.2018.08.030] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/30/2018] [Accepted: 08/20/2018] [Indexed: 01/19/2023]
Abstract
Acute infection, if not kept in check, can lead to systemic inflammatory responses in the brain. Here, we show that within 2 hr of systemic inflammation, PDGFRβ mural cells of blood vessels rapidly secrete chemokine CCL2, which in turn increases total neuronal excitability by promoting excitatory synaptic transmission in glutamatergic neurons of multiple brain regions. By single-cell RNA sequencing, we identified Col1a1 and Rgs5 subgroups of PDGFRβ cells as the main source of CCL2. Lipopolysaccharide (LPS)- or Poly(I:C)-treated pericyte culture medium induced similar effects in a CCL2-dependent manner. Importantly, in Pdgfrb-Cre;Ccl2fl/fl mice, LPS-induced increase in excitatory synaptic transmission was significantly attenuated. These results demonstrate in vivo that PDGFRβ cells function as initial sensors of external insults by secreting CCL2, which relays the signal to the central nervous system. Through their gateway position in the brain, PDGFRβ cells are ideally positioned to respond rapidly to environmental changes and to coordinate responses.
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Affiliation(s)
- Lihui Duan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Di Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wan-Ying Miao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yun-Jun Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Guoliang Xiong
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiuzi Wu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Guangying Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ping Yang
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Hang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Humingzhu Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yue Wang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Min Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Li-Yuan Hu
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Xiaoping Tong
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wen-Hao Zhou
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Xiang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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21
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Kolinko Y, Kralickova M, Tonar Z. The impact of pericytes on the brain and approaches for their morphological analysis. J Chem Neuroanat 2018; 91:35-45. [DOI: 10.1016/j.jchemneu.2018.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/10/2018] [Accepted: 04/15/2018] [Indexed: 12/15/2022]
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22
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Abstract
While there is a growing consensus that insulin has diverse and important regulatory actions on the brain, seemingly important aspects of brain insulin physiology are poorly understood. Examples include: what is the insulin concentration within brain interstitial fluid under normal physiologic conditions; whether insulin is made in the brain and acts locally; does insulin from the circulation cross the blood-brain barrier or the blood-CSF barrier in a fashion that facilitates its signaling in brain; is insulin degraded within the brain; do privileged areas with a "leaky" blood-brain barrier serve as signaling nodes for transmitting peripheral insulin signaling; does insulin action in the brain include regulation of amyloid peptides; whether insulin resistance is a cause or consequence of processes involved in cognitive decline. Heretofore, nearly all of the studies examining brain insulin physiology have employed techniques and methodologies that do not appreciate the complex fluid compartmentation and flow throughout the brain. This review attempts to provide a status report on historical and recent work that begins to address some of these issues. It is undertaken in an effort to suggest a framework for studies going forward. Such studies are inevitably influenced by recent physiologic and genetic studies of insulin accessing and acting in brain, discoveries relating to brain fluid dynamics and the interplay of cerebrospinal fluid, brain interstitial fluid, and brain lymphatics, and advances in clinical neuroimaging that underscore the dynamic role of neurovascular coupling.
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Affiliation(s)
- Sarah M Gray
- Department of Pharmacology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia
| | - Eugene J Barrett
- Department of Pharmacology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia.,Division of Endocrinology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia
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23
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Guerra G, Lucariello A, Perna A, Botta L, De Luca A, Moccia F. The Role of Endothelial Ca 2+ Signaling in Neurovascular Coupling: A View from the Lumen. Int J Mol Sci 2018; 19:E938. [PMID: 29561829 PMCID: PMC5979341 DOI: 10.3390/ijms19040938] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+-dependent manner throughout peripheral vasculature. METHODS We analyzed the literature in search of the most recent updates on the potential role of endothelial Ca2+ signaling in NVC. RESULTS We found that several neurotransmitters (i.e., glutamate and acetylcholine) and neuromodulators (e.g., ATP) can induce dilation of cerebral vessels by inducing an increase in endothelial Ca2+ concentration. This, in turn, results in nitric oxide or prostaglandin E2 release or activate intermediate and small-conductance Ca2+-activated K⁺ channels, which are responsible for endothelial-dependent hyperpolarization (EDH). In addition, brain endothelial cells express multiple transient receptor potential (TRP) channels (i.e., TRPC3, TRPV3, TRPV4, TRPA1), which induce vasodilation by activating EDH. CONCLUSIONS It is possible to conclude that endothelial Ca2+ signaling is an emerging pathway in the control of NVC.
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Affiliation(s)
- Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Angela Lucariello
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
| | - Antonio De Luca
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
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24
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Johnson AC, Cipolla MJ. Altered hippocampal arteriole structure and function in a rat model of preeclampsia: Potential role in impaired seizure-induced hyperemia. J Cereb Blood Flow Metab 2017; 37:2857-2869. [PMID: 27815419 PMCID: PMC5536792 DOI: 10.1177/0271678x16676287] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 11/16/2022]
Abstract
We investigated the effect of experimental preeclampsia on hyperemia during seizure in the hippocampus and vascular function and structure of hippocampal arterioles using Sprague Dawley rats (n = 14/group) that were nonpregnant, pregnant (d20), or had experimental preeclampsia (induced by a high cholesterol diet d7-20). Hyperemia was measured via hydrogen clearance basally and during pentylenetetrazol-induced seizure (40-130 mg/kg i.v.). Reactivity of isolated and pressurized hippocampal arterioles to KCl, nitric oxide synthase inhibition with NG-nitro-L-arginine methyl ester and the nitric oxide donor sodium nitroprusside were investigated. Capillary density was quantified via immunohistochemistry. Cerebral blood flow increased during seizure vs. baseline in pregnant (118 ± 14 vs. 87 ± 9 mL/100 g/min; p < 0.05) and nonpregnant rats (106 ± 9 vs. 82 ± 9 mL/100 g/min; p < 0.05) but was unchanged in preeclamptic rats (79 ± 16 vs. 91 ± 4 mL/100 g/min; p > 0.05), suggesting impaired seizure-induced hyperemia in preeclampsia. Hippocampal arterioles from preeclamptic rats had less basal tone, and dilated less to 15 mM KCl (9 ± 8%) vs. pregnant (61 ± 27%) and nonpregnant rats (20 ± 11%). L-NAME had no effect on hippocampal arterioles in any group, but dilation to sodium nitroprusside was similar. Structurally, hippocampal arterioles from preeclamptic rats underwent inward hypotrophic remodeling and capillary rarefaction. Impaired seizure-induced hyperemia, vascular dysfunction, and limited vasodilatory reserve of hippocampal arterioles could potentiate hippocampal injury in preeclampsia especially during eclampsia.
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Affiliation(s)
- Abbie C Johnson
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, USA
| | - Marilyn J Cipolla
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Vermont College of Medicine, Burlington, USA
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, USA
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25
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Sweeney MD, Ayyadurai S, Zlokovic BV. Pericytes of the neurovascular unit: key functions and signaling pathways. Nat Neurosci 2017; 19:771-83. [PMID: 27227366 DOI: 10.1038/nn.4288] [Citation(s) in RCA: 706] [Impact Index Per Article: 100.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/29/2016] [Indexed: 12/12/2022]
Abstract
Pericytes are vascular mural cells embedded in the basement membrane of blood microvessels. They extend their processes along capillaries, pre-capillary arterioles and post-capillary venules. CNS pericytes are uniquely positioned in the neurovascular unit between endothelial cells, astrocytes and neurons. They integrate, coordinate and process signals from their neighboring cells to generate diverse functional responses that are critical for CNS functions in health and disease, including regulation of the blood-brain barrier permeability, angiogenesis, clearance of toxic metabolites, capillary hemodynamic responses, neuroinflammation and stem cell activity. Here we examine the key signaling pathways between pericytes and their neighboring endothelial cells, astrocytes and neurons that control neurovascular functions. We also review the role of pericytes in CNS disorders including rare monogenic diseases and complex neurological disorders such as Alzheimer's disease and brain tumors. Finally, we discuss directions for future studies.
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Affiliation(s)
- Melanie D Sweeney
- Department of Physiology and Biophysics, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA.,Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Shiva Ayyadurai
- Systems Biology Group, CytoSolve Research Division, Cambridge, Massachusetts, USA
| | - Berislav V Zlokovic
- Department of Physiology and Biophysics, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA.,Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
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26
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Lourenço CF, Ledo A, Barbosa RM, Laranjinha J. Neurovascular-neuroenergetic coupling axis in the brain: master regulation by nitric oxide and consequences in aging and neurodegeneration. Free Radic Biol Med 2017; 108:668-682. [PMID: 28435052 DOI: 10.1016/j.freeradbiomed.2017.04.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 02/21/2017] [Accepted: 04/18/2017] [Indexed: 02/08/2023]
Abstract
The strict energetic demands of the brain require that nutrient supply and usage be fine-tuned in accordance with the specific temporal and spatial patterns of ever-changing levels of neuronal activity. This is achieved by adjusting local cerebral blood flow (CBF) as a function of activity level - neurovascular coupling - and by changing how energy substrates are metabolized and shuttled amongst astrocytes and neurons - neuroenergetic coupling. Both activity-dependent increase of CBF and O2 and glucose utilization by active neural cells are inextricably linked, establishing a functional metabolic axis in the brain, the neurovascular-neuroenergetic coupling axis. This axis incorporates and links previously independent processes that need to be coordinated in the normal brain. We here review evidence supporting the role of neuronal-derived nitric oxide (•NO) as the master regulator of this axis. Nitric oxide is produced in tight association with glutamatergic activation and, diffusing several cell diameters, may interact with different molecular targets within each cell type. Hemeproteins such as soluble guanylate cyclase, cytochrome c oxidase and hemoglobin, with which •NO reacts at relatively fast rates, are but a few of the key in determinants of the regulatory role of •NO in the neurovascular-neuroenergetic coupling axis. Accordingly, critical literature supporting this concept is discussed. Moreover, in view of the controversy regarding the regulation of catabolism of different neural cells, we further discuss key aspects of the pathways through which •NO specifically up-regulates glycolysis in astrocytes, supporting lactate shuttling to neurons for oxidative breakdown. From a biomedical viewpoint, derailment of neurovascular-neuroenergetic axis is precociously linked to aberrant brain aging, cognitive impairment and neurodegeneration. Thus, we summarize current knowledge of how both neurovascular and neuroenergetic coupling are compromised in aging, traumatic brain injury, epilepsy and age-associated neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, suggesting that a shift in cellular redox balance may contribute to divert •NO bioactivity from regulation to dysfunction.
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Affiliation(s)
- Cátia F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Ana Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Rui M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - João Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
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27
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Phillips AA, Chan FH, Zheng MMZ, Krassioukov AV, Ainslie PN. Neurovascular coupling in humans: Physiology, methodological advances and clinical implications. J Cereb Blood Flow Metab 2016; 36:647-64. [PMID: 26661243 PMCID: PMC4821024 DOI: 10.1177/0271678x15617954] [Citation(s) in RCA: 260] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/16/2022]
Abstract
Neurovascular coupling reflects the close temporal and regional linkage between neural activity and cerebral blood flow. Although providing mechanistic insight, our understanding of neurovascular coupling is largely limited to non-physiologicalex vivopreparations and non-human models using sedatives/anesthetics with confounding cerebrovascular implications. Herein, with particular focus on humans, we review the present mechanistic understanding of neurovascular coupling and highlight current approaches to assess these responses and the application in health and disease. Moreover, we present new guidelines for standardizing the assessment of neurovascular coupling in humans. To improve the reliability of measurement and related interpretation, the utility of new automated software for neurovascular coupling is demonstrated, which provides the capacity for coalescing repetitive trials and time intervals into single contours and extracting numerous metrics (e.g., conductance and pulsatility, critical closing pressure, etc.) according to patterns of interest (e.g., peak/minimum response, time of response, etc.). This versatile software also permits the normalization of neurovascular coupling metrics to dynamic changes in arterial blood gases, potentially influencing the hyperemic response. It is hoped that these guidelines, combined with the newly developed and openly available software, will help to propel the understanding of neurovascular coupling in humans and also lead to improved clinical management of this critical physiological function.
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Affiliation(s)
- Aaron A Phillips
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada
| | - Franco Hn Chan
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada
| | - Mei Mu Zi Zheng
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada
| | - Andrei V Krassioukov
- International Collaboration on Repair Discoveries (ICORD), UBC, Vancouver, Canada Experimental Medicine Program, Faculty of Medicine, UBC, Vancouver, Canada Department of Physical Therapy, UBC, Vancouver, Canada GF Strong Rehabilitation Center, Vancouver, Canada Department of Medicine, Division of Physical Medicine and Rehabilitation, UBC, Vancouver, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
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Kozberg M, Hillman E. Neurovascular coupling and energy metabolism in the developing brain. PROGRESS IN BRAIN RESEARCH 2016; 225:213-42. [PMID: 27130418 DOI: 10.1016/bs.pbr.2016.02.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In the adult brain, increases in local neural activity are almost always accompanied by increases in local blood flow. However, many functional imaging studies of the newborn and developing human brain have observed patterns of hemodynamic responses that differ from adult responses. Among the proposed mechanisms for the observed variations is that neurovascular coupling itself is still developing in the perinatal brain. Many of the components thought to be involved in actuating and propagating this hemodynamic response are known to still be developing postnatally, including perivascular cells such as astrocytes and pericytes. Both neural and vascular networks expand and are then selectively pruned over the first year of human life. Additionally, the metabolic demands of the newborn brain are still evolving. These changes are highly likely to affect early postnatal neurovascular coupling, and thus may affect functional imaging signals in this age group. This chapter will discuss the literature relating to neurovascular development. Potential effects of normal and aberrant development of neurovascular coupling on the newborn brain will also be explored, as well as ways to effectively utilize imaging techniques that rely on hemodynamic modulation such as fMRI and NIRS in younger populations.
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Affiliation(s)
- M Kozberg
- Columbia University, New York, NY, United States.
| | - E Hillman
- Columbia University, New York, NY, United States; Kavli Institute for Brain Science, Columbia University, New York, NY, United States; Mortimer B. Zuckerman Institute for Mind Brain and Behavior, Columbia University, New York, NY, United States.
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COX-2-Derived Prostaglandin E2 Produced by Pyramidal Neurons Contributes to Neurovascular Coupling in the Rodent Cerebral Cortex. J Neurosci 2015; 35:11791-810. [PMID: 26311764 DOI: 10.1523/jneurosci.0651-15.2015] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Vasodilatory prostaglandins play a key role in neurovascular coupling (NVC), the tight link between neuronal activity and local cerebral blood flow, but their precise identity, cellular origin and the receptors involved remain unclear. Here we show in rats that NMDA-induced vasodilation and hemodynamic responses evoked by whisker stimulation involve cyclooxygenase-2 (COX-2) activity and activation of the prostaglandin E2 (PgE2) receptors EP2 and EP4. Using liquid chromatography-electrospray ionization-tandem mass spectrometry, we demonstrate that PgE2 is released by NMDA in cortical slices. The characterization of PgE2 producing cells by immunohistochemistry and single-cell reverse transcriptase-PCR revealed that pyramidal cells and not astrocytes are the main cell type equipped for PgE2 synthesis, one third expressing COX-2 systematically associated with a PgE2 synthase. Consistent with their central role in NVC, in vivo optogenetic stimulation of pyramidal cells evoked COX-2-dependent hyperemic responses in mice. These observations identify PgE2 as the main prostaglandin mediating sensory-evoked NVC, pyramidal cells as their principal source and vasodilatory EP2 and EP4 receptors as their targets. SIGNIFICANCE STATEMENT Brain function critically depends on a permanent spatiotemporal match between neuronal activity and blood supply, known as NVC. In the cerebral cortex, prostaglandins are major contributors to NVC. However, their biochemical identity remains elusive and their cellular origins are still under debate. Although astrocytes can induce vasodilations through the release of prostaglandins, the recruitment of this pathway during sensory stimulation is questioned. Using multidisciplinary approaches from single-cell reverse transcriptase-PCR, mass spectrometry, to ex vivo and in vivo pharmacology and optogenetics, we provide compelling evidence identifying PgE2 as the main prostaglandin in NVC, pyramidal neurons as their main cellular source and the vasodilatory EP2 and EP4 receptors as their main targets. These original findings will certainly change the current view of NVC.
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COX-2-Derived Prostaglandin E2 Produced by Pyramidal Neurons Contributes to Neurovascular Coupling in the Rodent Cerebral Cortex. J Neurosci 2015. [PMID: 26311764 DOI: 10.1523/jneurosci.0651‐15.2015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Vasodilatory prostaglandins play a key role in neurovascular coupling (NVC), the tight link between neuronal activity and local cerebral blood flow, but their precise identity, cellular origin and the receptors involved remain unclear. Here we show in rats that NMDA-induced vasodilation and hemodynamic responses evoked by whisker stimulation involve cyclooxygenase-2 (COX-2) activity and activation of the prostaglandin E2 (PgE2) receptors EP2 and EP4. Using liquid chromatography-electrospray ionization-tandem mass spectrometry, we demonstrate that PgE2 is released by NMDA in cortical slices. The characterization of PgE2 producing cells by immunohistochemistry and single-cell reverse transcriptase-PCR revealed that pyramidal cells and not astrocytes are the main cell type equipped for PgE2 synthesis, one third expressing COX-2 systematically associated with a PgE2 synthase. Consistent with their central role in NVC, in vivo optogenetic stimulation of pyramidal cells evoked COX-2-dependent hyperemic responses in mice. These observations identify PgE2 as the main prostaglandin mediating sensory-evoked NVC, pyramidal cells as their principal source and vasodilatory EP2 and EP4 receptors as their targets. SIGNIFICANCE STATEMENT Brain function critically depends on a permanent spatiotemporal match between neuronal activity and blood supply, known as NVC. In the cerebral cortex, prostaglandins are major contributors to NVC. However, their biochemical identity remains elusive and their cellular origins are still under debate. Although astrocytes can induce vasodilations through the release of prostaglandins, the recruitment of this pathway during sensory stimulation is questioned. Using multidisciplinary approaches from single-cell reverse transcriptase-PCR, mass spectrometry, to ex vivo and in vivo pharmacology and optogenetics, we provide compelling evidence identifying PgE2 as the main prostaglandin in NVC, pyramidal neurons as their main cellular source and the vasodilatory EP2 and EP4 receptors as their main targets. These original findings will certainly change the current view of NVC.
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31
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Neuronal-derived nitric oxide and somatodendritically released vasopressin regulate neurovascular coupling in the rat hypothalamic supraoptic nucleus. J Neurosci 2015; 35:5330-41. [PMID: 25834057 DOI: 10.1523/jneurosci.3674-14.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The classical model of neurovascular coupling (NVC) implies that activity-dependent axonal glutamate release at synapses evokes the production and release of vasoactive signals from both neurons and astrocytes, which dilate arterioles, increasing in turn cerebral blood flow (CBF) to areas with increased metabolic needs. However, whether this model is applicable to brain areas that also use less conventional neurotransmitters, such as neuropeptides, is currently unknown. To this end, we studied NVC in the rat hypothalamic magnocellular neurosecretory system (MNS) of the supraoptic nucleus (SON), in which dendritic release of neuropeptides, including vasopressin (VP), constitutes a key signaling modality influencing neuronal and network activity. Using a multidisciplinary approach, we investigated vasopressin-mediated vascular responses in SON arterioles of hypothalamic brain slices of Wistar or VP-eGFP Wistar rats. Bath-applied VP significantly constricted SON arterioles (Δ-41 ± 7%) via activation of the V1a receptor subtype. Vasoconstrictions were also observed in response to single VP neuronal stimulation (Δ-18 ± 2%), an effect prevented by V1a receptor blockade (V2255), supporting local dendritic VP release as the key signal mediating activity-dependent vasoconstrictions. Conversely, osmotically driven magnocellular neurosecretory neuronal population activity leads to a predominant nitric oxide-mediated vasodilation (Δ19 ± 2%). Activity-dependent vasodilations were followed by a VP-mediated vasoconstriction, which acted to limit the magnitude of the vasodilation and served to reset vascular tone following activity-dependent vasodilation. Together, our results unveiled a unique and complex form of NVC in the MNS, supporting a competitive balance between nitric oxide and activity-dependent dendritic released VP, in the generation of proper NVC responses.
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32
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Lourenço CF, Santos RM, Barbosa RM, Cadenas E, Radi R, Laranjinha J. Neurovascular coupling in hippocampus is mediated via diffusion by neuronal-derived nitric oxide. Free Radic Biol Med 2014; 73:421-9. [PMID: 24887095 DOI: 10.1016/j.freeradbiomed.2014.05.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/19/2014] [Accepted: 05/23/2014] [Indexed: 02/08/2023]
Abstract
The coupling between neuronal activity and cerebral blood flow (CBF) is essential for normal brain function. The mechanisms behind this neurovascular coupling process remain elusive, mainly because of difficulties in probing dynamically the functional and coordinated interaction between neurons and the vasculature in vivo. Direct and simultaneous measurements of nitric oxide (NO) dynamics and CBF changes in hippocampus in vivo support the notion that during glutamatergic activation nNOS-derived NO induces a time-, space-, and amplitude-coupled increase in the local CBF, later followed by a transient increase in local O2 tension. These events are dependent on the activation of the NMDA-glutamate receptor and nNOS, without a significant contribution of endothelial-derived NO or astrocyte-neuron signaling pathways. Upon diffusion of NO from active neurons, the vascular response encompasses the activation of soluble guanylate cyclase. Hence, in the hippocampus, neurovascular coupling is mediated by nNOS-derived NO via a diffusional connection between active glutamatergic neurons and blood vessels.
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Affiliation(s)
- Cátia F Lourenço
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Ricardo M Santos
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Rui M Barbosa
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Enrique Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA
| | - Rafael Radi
- Department of Biochemistry and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - João Laranjinha
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal.
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Hall CN, Reynell C, Gesslein B, Hamilton NB, Mishra A, Sutherland BA, O'Farrell FM, Buchan AM, Lauritzen M, Attwell D. Capillary pericytes regulate cerebral blood flow in health and disease. Nature 2014; 508:55-60. [PMID: 24670647 PMCID: PMC3976267 DOI: 10.1038/nature13165] [Citation(s) in RCA: 1269] [Impact Index Per Article: 126.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 02/19/2014] [Indexed: 01/12/2023]
Abstract
Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate that neuronal activity and the neurotransmitter glutamate evoke the release of messengers that dilate capillaries by actively relaxing pericytes. Dilation is mediated by prostaglandin E2, but requires nitric oxide release to suppress vasoconstricting 20-HETE synthesis. In vivo, when sensory input increases blood flow, capillaries dilate before arterioles and are estimated to produce 84% of the blood flow increase. In pathology, ischaemia evokes capillary constriction by pericytes. We show that this is followed by pericyte death in rigor, which may irreversibly constrict capillaries and damage the blood-brain barrier. Thus, pericytes are major regulators of cerebral blood flow and initiators of functional imaging signals. Prevention of pericyte constriction and death may reduce the long-lasting blood flow decrease that damages neurons after stroke.
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Affiliation(s)
- Catherine N Hall
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
| | - Clare Reynell
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
| | - Bodil Gesslein
- Department of Neuroscience & Pharmacology and Center for Healthy Aging, and Department of Clinical Neurophysiology, Glostrup Hospital, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Nicola B Hamilton
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
| | - Anusha Mishra
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
| | - Brad A Sutherland
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Fergus M O'Farrell
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
| | - Alastair M Buchan
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Martin Lauritzen
- Department of Neuroscience & Pharmacology and Center for Healthy Aging, and Department of Clinical Neurophysiology, Glostrup Hospital, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology University College London, Gower St., London, WC1E 6BT, UK
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Muoio V, Persson PB, Sendeski MM. The neurovascular unit - concept review. Acta Physiol (Oxf) 2014; 210:790-8. [PMID: 24629161 DOI: 10.1111/apha.12250] [Citation(s) in RCA: 340] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/01/2013] [Accepted: 01/27/2014] [Indexed: 01/01/2023]
Abstract
The cerebral hyperaemia is one of the fundamental mechanisms for the central nervous system homeostasis. Due also to this mechanism, oxygen and nutrients are maintained in satisfactory levels, through vasodilation and vasoconstriction. The brain hyperaemia, or coupling, is accomplished by a group of cells, closely related to each other; called neurovascular unit (NVU). The neurovascular unit is composed by neurones, astrocytes, endothelial cells of blood-brain barrier (BBB), myocytes, pericytes and extracellular matrix components. These cells, through their intimate anatomical and chemical relationship, detect the needs of neuronal supply and trigger necessary responses (vasodilation or vasoconstriction) for such demands. Here, we review the concepts of NVU, the coupling mechanisms and research strategies.
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Affiliation(s)
- V. Muoio
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
| | - P. B. Persson
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
| | - M. M. Sendeski
- Institut für Vegetative Physiologie; Charite- Universisitätmedizin Berlin; Berlin Germany
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Rocha-de-Melo AP, Picanço-Diniz CW, Borba JMC, Santos-Monteiro J, Guedes RCA. NADPH-diaphorase Histochemical Labeling Patterns in the Hippocampal Neuropil and Visual Cortical Neurons in Weaned Rats Reared during Lactation on Different Litter Sizes. Nutr Neurosci 2013; 7:207-16. [PMID: 15682647 DOI: 10.1080/10284150400001961] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Tissue distribution of nitric oxide-synthases was investigated in the rat hippocampus and visual cortex under nutritional changes induced by modification of the litter size. Young (30-45-days-old) rats, suckled in litters formed by 3,6 or 12 pups (called small, medium and large litters, respectively), were studied by using nicotine-adenine-dinucleotide phosphate-diaphorase histochemistry (shortly, diaphorase), a simple and robust procedure to characterize tissue distribution of nitric oxide-synthases. We assessed morphometric features of the diaphorase-positive cells in visual cortex, and the neuropil histochemical activity in hippocampal CA1 and dentate gyrus using densitometry analysis. In the large-litter group, the labeled-cell density in white matter of area 17 was higher, as compared to the small-litter group. There was a clear trend, in the large-litter group, to lower values of soma area, dendritic field and branches per neuron, but the differences were not significant. Densitometry analysis of hippocampus revealed a significant increase in the relative neuropil histochemical activity of the dentate gyrus molecular layer in the larger litters, which may be associated to increased compensatory blood flow in the hippocampus. The pathophysiological mechanisms of the observed changes remain to be investigated.
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Affiliation(s)
- Ana Paula Rocha-de-Melo
- Departamento de Nutrição, Universidade Federal de Pernambuco, BR-50670-901, Recife, PE, Brazil
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Abstract
Cerebral blood flow is controlled by two crucial processes, cerebral autoregulation (CA) and neurovascular coupling (NVC) or functional hyperemia. Whereas CA ensures constant blood flow over a wide range of systemic pressures, NVC ensures rapid spatial and temporal increases in cerebral blood flow in response to neuronal activation. The focus of this review is to discuss the cellular mechanisms by which astrocytes contribute to the regulation of vascular tone in terms of their participation in NVC and, to a lesser extent, CA. We discuss evidence for the various signaling modalities by which astrocytic activation leads to vasodilation and vasoconstriction of parenchymal arterioles. Moreover, we provide a rationale for the contribution of astrocytes to pressure-induced increases in vascular tone via the vasoconstrictor 20-HETE (a downstream metabolite of arachidonic acid). Along these lines, we highlight the importance of the transient receptor potential channel of the vanilloid family (TRPV4) as a key molecular determinant in the regulation of vascular tone in cerebral arterioles. Finally, we discuss current advances in the technical tools available to study NVC mechanisms in the brain as it relates to the participation of astrocytes.
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Perrenoud Q, Rossier J, Férézou I, Geoffroy H, Gallopin T, Vitalis T, Rancillac A. Activation of cortical 5-HT(3) receptor-expressing interneurons induces NO mediated vasodilatations and NPY mediated vasoconstrictions. Front Neural Circuits 2012; 6:50. [PMID: 22907992 PMCID: PMC3415676 DOI: 10.3389/fncir.2012.00050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/10/2012] [Indexed: 11/17/2022] Open
Abstract
GABAergic interneurons are local integrators of cortical activity that have been reported to be involved in the control of cerebral blood flow (CBF) through their ability to produce vasoactive molecules and their rich innervation of neighboring blood vessels. They form a highly diverse population among which the serotonin 5-hydroxytryptamine 3A receptor (5-HT3A)-expressing interneurons share a common developmental origin, in addition to the responsiveness to serotonergic ascending pathway. We have recently shown that these neurons regroup two distinct subpopulations within the somatosensory cortex: Neuropeptide Y (NPY)-expressing interneurons, displaying morphological properties similar to those of neurogliaform cells and Vasoactive Intestinal Peptide (VIP)-expressing bipolar/bitufted interneurons. The aim of the present study was to determine the role of these neuronal populations in the control of vascular tone by monitoring blood vessels diameter changes, using infrared videomicroscopy in mouse neocortical slices. Bath applications of 1-(3-Chlorophenyl)biguanide hydrochloride (mCPBG), a 5-HT3R agonist, induced both constrictions (30%) and dilations (70%) of penetrating arterioles within supragranular layers. All vasoconstrictions were abolished in the presence of the NPY receptor antagonist (BIBP 3226), suggesting that they were elicited by NPY release. Vasodilations persisted in the presence of the VIP receptor antagonist VPAC1 (PG-97-269), whereas they were blocked in the presence of the neuronal Nitric Oxide (NO) Synthase (nNOS) inhibitor, L-NNA. Altogether, these results strongly suggest that activation of neocortical 5-HT3A-expressing interneurons by serotoninergic input could induces NO mediated vasodilatations and NPY mediated vasoconstrictions.
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Affiliation(s)
- Quentin Perrenoud
- Laboratoire de Neurobiologie, CNRS UMR 7637, ESPCI ParisTech Paris, France
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Laranjinha J, Santos RM, Lourenço CF, Ledo A, Barbosa RM. Nitric oxide signaling in the brain: translation of dynamics into respiration control and neurovascular coupling. Ann N Y Acad Sci 2012; 1259:10-8. [DOI: 10.1111/j.1749-6632.2012.06582.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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NMDA receptors in hippocampal GABAergic synapses and their role in nitric oxide signaling. J Neurosci 2011; 31:5893-904. [PMID: 21508214 DOI: 10.1523/jneurosci.5938-10.2011] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
GABAergic inhibition plays a central role in the control of pyramidal cell ensemble activities; thus, any signaling mechanism that regulates inhibition is able to fine-tune network patterns. Here, we provide evidence that the retrograde nitric oxide (NO)-cGMP cascade triggered by NMDA receptor (NMDAR) activation plays a role in the control of hippocampal GABAergic transmission in mice. GABAergic synapses express neuronal nitric oxide synthase (nNOS) postsynaptically and NO receptors (NO-sensitive guanylyl cyclase) in the presynaptic terminals. We hypothesized that--similar to glutamatergic synapses--the Ca(2+) transients required to activate nNOS were provided by NMDA receptor activation. Indeed, administration of 5 μm NMDA induced a robust nNOS-dependent cGMP production in GABAergic terminals, selectively in the CA1 and CA3c areas. Furthermore, using preembedding, postembedding, and SDS-digested freeze-fracture replica immunogold labeling, we provided quantitative immunocytochemical evidence that NMDAR subunits GluN1, GluN2A, and GluN2B were present in most somatic GABAergic synapses postsynaptically. These data indicate that NMDARs can modulate hippocampal GABAergic inhibition via NO-cGMP signaling in an activity-dependent manner and that this effect is subregion specific in the mouse hippocampus.
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Gómez-Gonzalo M, Losi G, Brondi M, Uva L, Sato SS, de Curtis M, Ratto GM, Carmignoto G. Ictal but not interictal epileptic discharges activate astrocyte endfeet and elicit cerebral arteriole responses. Front Cell Neurosci 2011; 5:8. [PMID: 21747758 PMCID: PMC3128928 DOI: 10.3389/fncel.2011.00008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 06/06/2011] [Indexed: 12/03/2022] Open
Abstract
Activation of astrocytes by neuronal signals plays a central role in the control of neuronal activity-dependent blood flow changes in the normal brain. The cellular pathways that mediate neurovascular coupling in the epileptic brain remain, however, poorly defined. In a cortical slice model of epilepsy, we found that the ictal, seizure-like discharge, and only to a minor extent the interictal discharge, evokes both a Ca2+ increase in astrocyte endfeet and a vasomotor response. We also observed that rapid ictal discharge-induced arteriole responses were regularly preceded by Ca2+ elevations in endfeet and were abolished by pharmacological inhibition of Ca2+ signals in these astrocyte processes. Under these latter conditions, arterioles exhibited after the ictal discharge only slowly developing vasodilations. The poor efficacy of interictal discharges, compared with ictal discharges, to activate endfeet was confirmed also in the intact in vitro isolated guinea pig brain. Although the possibility of a direct contribution of neurons, in particular in the late response of cerebral blood vessels to epileptic discharges, should be taken into account, our study supports the view that astrocytes are central for neurovascular coupling also in the epileptic brain. The massive endfeet Ca2+ elevations evoked by ictal discharges and the poor response to interictal events represent new information potentially relevant to interpret data from diagnostic brain imaging techniques, such as functional magnetic resonance, utilized in the clinic to localize neural activity and to optimize neurosurgery of untreatable epilepsies.
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42
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Pharmacological MRI approaches to understanding mechanisms of drug action. Curr Top Behav Neurosci 2011; 11:365-88. [PMID: 22057623 DOI: 10.1007/7854_2011_177] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Functional neuroimaging is a novel technique for the study of drug action in the brain. The emerging role of this method is intimately tied to the unique challenges to advancing drug development for neuropsychiatric disorders. This chapter first presents a brief overview of the important treatment needs that remain to be met, which serve as clinical targets for drug development. Important factors that hinder progress in drug development, which arise from clinical, scientific and economic issues, are acknowledged. This sets the stage for the unique advantages of functional neuroimaging modalities such as functional MRI (fMRI) as a biomarker and drug development tool, in both clinical and preclinical phases. The physiological basis of the fMRI signal is briefly outlined, and aspects of neural signaling related to this signal change, with emphasis on implications for pharmacology studies. The utility of fMRI for evaluating the full anatomic extent of central neurotransmitter systems in a dynamic manner is then described. This is a critical advantage, and particularly important for studies of how systems such as the monoamines modulate distributed neural networks during cognitive processes in both health and illness, and how these actions are modified with pharmacological intervention. Central catecholamine systems are seen as paradigmatic targets amenable to pharmacologic fMRI. fMRI is observed to occupy a unique position in the armamentarium of methods available to the pharmacologist and the drug development process, and poised to play an expanding role in basic and clinical neuroscience.
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McHugh SB, Fillenz M, Lowry JP, Rawlins JNP, Bannerman DM. Brain tissue oxygen amperometry in behaving rats demonstrates functional dissociation of dorsal and ventral hippocampus during spatial processing and anxiety. Eur J Neurosci 2010; 33:322-37. [PMID: 21105915 PMCID: PMC3085075 DOI: 10.1111/j.1460-9568.2010.07497.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Traditionally, the function of the hippocampus (HPC) has been viewed in unitary terms, but there is growing evidence that the HPC is functionally differentiated along its septotemporal axis. Lesion studies in rodents and functional brain imaging in humans suggest a preferential role for the septal HPC in spatial learning and a preferential role for the temporal HPC in anxiety. To better enable cross-species comparison, we present an in vivo amperometric technique that measures changes in brain tissue oxygen at high temporal resolution in freely-moving rats. We recorded simultaneously from the dorsal (septal; dHPC) and ventral (temporal; vHPC) HPC during two anxiety tasks and two spatial tasks on the radial maze. We found a double-dissociation of function in the HPC, with increased vHPC signals during anxiety and increased dHPC signals during spatial processing. In addition, dHPC signals were modulated by spatial memory demands. These results add a new dimension to the growing consensus for a differentiation of HPC function, and highlight tissue oxygen amperometry as a valuable tool to aid translation between animal and human research.
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Affiliation(s)
- Stephen B McHugh
- Department of Psychology, University of Oxford, Oxford, South Parks Road, Oxford OX1 3UD, UK.
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44
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Attwell D, Buchan AM, Charpak S, Lauritzen M, Macvicar BA, Newman EA. Glial and neuronal control of brain blood flow. Nature 2010; 468:232-43. [PMID: 21068832 PMCID: PMC3206737 DOI: 10.1038/nature09613] [Citation(s) in RCA: 1665] [Impact Index Per Article: 118.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches.
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Affiliation(s)
- David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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45
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Filosa JA. Vascular tone and neurovascular coupling: considerations toward an improved in vitro model. FRONTIERS IN NEUROENERGETICS 2010; 2:16. [PMID: 20802803 PMCID: PMC2928708 DOI: 10.3389/fnene.2010.00016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 06/28/2010] [Indexed: 11/13/2022]
Abstract
Neurovascular research has made significant strides toward understanding how the brain neurovascular unit accomplishes rapid and spatial increases in blood flow following neuronal activation. Among the experimental models used, the in vitro brain slice preparation provides unique information revealing the potential signals and cellular mechanisms involved in functional hyperemia. The most crucial limitation of this model, however, is the lack of intraluminal pressure and flow in the vessels being studied. Moreover, differences in basal vascular tone have led to varied interpretations regarding the polarity of vascular responses following neuron-to-glial stimulation. Given the complexity of astrocyte-induced neurovascular responses, we propose the use of a modified in vitro brain slice preparation, where intraluminal arteriolar pressure and flow are retained. Throughout this review, we discuss the advantages and disadvantages to be considered when using brain slices for neurovascular studies. Potential ways to overcome the current limitations are proposed.
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Affiliation(s)
- Jessica A. Filosa
- Department of Physiology, Medical College of GeorgiaAugusta, GA, USA
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Hamilton NB, Attwell D, Hall CN. Pericyte-mediated regulation of capillary diameter: a component of neurovascular coupling in health and disease. FRONTIERS IN NEUROENERGETICS 2010; 2. [PMID: 20725515 PMCID: PMC2912025 DOI: 10.3389/fnene.2010.00005] [Citation(s) in RCA: 344] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 04/28/2010] [Indexed: 12/18/2022]
Abstract
Because regional blood flow increases in association with the increased metabolic demand generated by localized increases in neural activity, functional imaging researchers often assume that changes in blood flow are an accurate read-out of changes in underlying neural activity. An understanding of the mechanisms that link changes in neural activity to changes in blood flow is crucial for assessing the validity of this assumption, and for understanding the processes that can go wrong during disease states such as ischaemic stroke. Many studies have investigated the mechanisms of neurovascular regulation in arterioles but other evidence suggests that blood flow regulation can also occur in capillaries, because of the presence of contractile cells, pericytes, on the capillary wall. Here we review the evidence that pericytes can modulate capillary diameter in response to neuronal activity and assess the likely importance of neurovascular regulation at the capillary level for functional imaging experiments. We also discuss evidence suggesting that pericytes are particularly sensitive to damage during pathological insults such as ischaemia, Alzheimer's disease and diabetic retinopathy, and consider the potential impact that pericyte dysfunction might have on the development of therapeutic interventions and on the interpretation of functional imaging data in these disorders.
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Affiliation(s)
- Nicola B Hamilton
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
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47
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Nitric oxide neurons and neurotransmission. Prog Neurobiol 2010; 90:246-55. [DOI: 10.1016/j.pneurobio.2009.10.007] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 04/22/2009] [Accepted: 10/09/2009] [Indexed: 11/24/2022]
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Norkute A, Hieble A, Braun A, Johann S, Clarner T, Baumgartner W, Beyer C, Kipp M. Cuprizone treatment induces demyelination and astrocytosis in the mouse hippocampus. J Neurosci Res 2009; 87:1343-55. [PMID: 19021291 DOI: 10.1002/jnr.21946] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Memory impairment is outstanding within the spectrum of cognitive deficits in multiple sclerosis (MS) patients. Demyelination has been reported in the hippocampus formation of MS patients. The degree of hippocampus lesions in MS strongly correlates with progression of cognitive dysfunction. Because no appropriate animal model for the study of hippocampus demyelination has been established, we used the cuprizone mouse model to investigated demyelination in young adult and aged mice. The myelin status was analyzed by classical histological staining, immunocytochemistry for proteolipoprotein, and electron microscopy. Oligodendrocyte, astroglial, and microglia markers were studied. Cuprizone intoxication induced an almost complete demyelination of distinct hippocampus subregions to a similar extent in young adult and aged male mice. Demyelination was pronounced in a subset of white and gray matter areas, i.e., the stratum lacunosum moleculare containing the perforant path, medial alveus, stratum pyramidale in the cornu ammonis 2/3 region, and hilus region. Besides demyelination, affected areas displayed hypertrophic and hyperplastic astrocytosis. No significant effect on microglia invasion was detected at any investigated time point (0, 3, 5, and 7 weeks). We conclude that cuprizone-induced demyelination provides an adequate animal model to investigate appropriate therapy strategies for the prevention of hippocampus demyelination.
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Affiliation(s)
- Akvile Norkute
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
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49
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Koehler RC, Roman RJ, Harder DR. Astrocytes and the regulation of cerebral blood flow. Trends Neurosci 2009; 32:160-9. [PMID: 19162338 DOI: 10.1016/j.tins.2008.11.005] [Citation(s) in RCA: 320] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 11/20/2008] [Accepted: 11/20/2008] [Indexed: 12/23/2022]
Abstract
Moment-to-moment changes in local neuronal activity lead to dynamic changes in cerebral blood flow. Emerging evidence implicates astrocytes as one of the key players in coordinating this neurovascular coupling. Astrocytes are poised to sense glutamatergic synaptic activity over a large spatial domain via activation of metabotropic glutamate receptors and subsequent calcium signaling and via energy-dependent glutamate transport. Astrocyte foot processes can signal vascular smooth muscle by arachidonic acid pathways involving astrocytic cytochrome P450 epoxygenase, astrocytic cyclooxygenase-1 and smooth muscle cytochrome P450 omega-hydroxylase activities, and by astrocytic and smooth muscle potassium channels. Non-glutamatergic transmitters released from neurons, such as nitric oxide, cyclooxygenase-2 metabolites and vasoactive intestinal peptide, might modulate neurovascular signaling at the level of the astrocyte or smooth muscle. Thus, astrocytes have a pivotal role in dynamic signaling within the neurovascular unit. Important questions remain on how this signaling is integrated with other pathways in health and disease.
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Affiliation(s)
- Raymond C Koehler
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21287, USA.
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50
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Kuga N, Hirata T, Sakai I, Tanikawa Y, Chiou HY, Kitanishi T, Matsuki N, Ikegaya Y. Rapid and local autoregulation of cerebrovascular blood flow: a deep-brain imaging study in the mouse. J Physiol 2008; 587:745-52. [PMID: 19074968 DOI: 10.1113/jphysiol.2008.163253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The brain obtains energy by keeping the cerebral blood flow constant against unexpected changes in systemic blood pressure. Although this homeostatic mechanism is widely known as cerebrovascular autoregulation, it is not understood how widely and how robustly it works in the brain. Using a needle-like objective lens designed for deep-tissue imaging, we quantified the degree of autoregulation in the mouse hippocampus with single-capillary resolution. On average, hippocampal blood flow exhibited autoregulation over a comparatively broad range of arterial blood pressure and did not significantly respond to pressure changes induced by the pharmacological activation of autonomic nervous system receptors, whereas peripheral tissues showed linear blood flow changes. At the level of individual capillaries, however, about 40% of hippocampal capillaries did not undergo rapid autoregulation. This heterogeneity suggests the presence of a local baroreflex system to implement cerebral autoregulation.
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Affiliation(s)
- Nahoko Kuga
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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