1
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Christensen J, Li C, Mychasiuk R. Choroid plexus function in neurological homeostasis and disorders: The awakening of the circadian clocks and orexins. J Cereb Blood Flow Metab 2022; 42:1163-1175. [PMID: 35296175 PMCID: PMC9207490 DOI: 10.1177/0271678x221082786] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
As research regarding the role of circadian rhythms, sleep, and the orexinergic system in neurodegenerative diseases is growing, it is surprising that the choroid plexus (CP) remains underappreciated in this realm. Despite its extensive role in the regulation of circadian rhythms and orexinergic signalling, as well as acting as the primary conduit between cerebrospinal fluid (CSF) and the circulatory system, providing a mechanism by which toxic waste molecules can be removed from the brain, the CP has been largely unexplored in neurodegeneration. In this review, we explore the role of the CP in maintaining brain homeostasis and circadian rhythms, regulating CSF dynamics, and how these functions change across the lifespan, from development to senescence. In addition, we examine the relationship between the CP, orexinergic signalling, and the glymphatic system, highlighting gaps in the literature and areas that require immediate exploration. Finally, we assess current knowledge, including possible therapeutic strategies, regarding the role of the CP in neurological disorders, such as traumatic brain injury, migraine, Alzheimer's disease, and multiple sclerosis.
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Affiliation(s)
- Jennaya Christensen
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Crystal Li
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
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2
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Abstract
The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.
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Affiliation(s)
- Martin Kaag Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
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3
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Deckmann I, Santos-Terra J, Fontes-Dutra M, Körbes-Rockenbach M, Bauer-Negrini G, Schwingel GB, Riesgo R, Bambini-Junior V, Gottfried C. Resveratrol prevents brain edema, blood-brain barrier permeability, and altered aquaporin profile in autism animal model. Int J Dev Neurosci 2021; 81:579-604. [PMID: 34196408 DOI: 10.1002/jdn.10137] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/08/2021] [Accepted: 06/21/2021] [Indexed: 12/17/2022] Open
Abstract
Autism spectrum disorder can present a plethora of clinical conditions associated with the disorder, such as greater brain volume in the first years of life in a significant percentage of patients. We aimed to evaluate the brain water content, the blood-brain barrier permeability, and the expression of aquaporin 1 and 4, and GFAP in a valproic acid-animal model, assessing the effect of resveratrol. On postnatal day 30, Wistar rats of the valproic acid group showed greater permeability of the blood-brain barrier to the Evans blue dye and a higher proportion of brain water volume, prevented both by resveratrol. Prenatal exposition to valproic acid diminished aquaporin 1 in the choroid plexus, in the primary somatosensory area, in the amygdala region, and in the medial prefrontal cortex, reduced aquaporin 4 in medial prefrontal cortex and increased aquaporin 4 levels in primary somatosensory area (with resveratrol prevention). Valproic acid exposition also increased the number of astrocytes and GFAP fluorescence in both primary somatosensory area and medial prefrontal cortex. In medial prefrontal cortex, resveratrol prevented the increased fluorescence. Finally, there was an effect of resveratrol per se on the number of astrocytes and GFAP fluorescence in the amygdala region and in the hippocampus. Thus, this work demonstrates significant changes in blood-brain barrier permeability, edema formation, distribution of aquaporin 1 and 4, in addition to astrocytes profile in the animal model of autism, as well as the use of resveratrol as a tool to investigate the mechanisms involved in the pathophysiology of autism spectrum disorder.
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Affiliation(s)
- Iohanna Deckmann
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
| | - Júlio Santos-Terra
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
| | - Mellanie Fontes-Dutra
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
| | - Marília Körbes-Rockenbach
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil
| | - Guilherme Bauer-Negrini
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
| | - Gustavo Brum Schwingel
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
| | - Rudimar Riesgo
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK.,Department of Pediatrics, Child Neurology Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Victorio Bambini-Junior
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK.,School of Pharmacology and Biomedical Sciences, University of Central Lancashire, Preston, UK
| | - Carmem Gottfried
- Translational Research Group in Autism Spectrum Disorder - GETTEA, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation - INCT-NIM, Porto Alegre, Brazil.,Autism Wellbeing and Research Development - AWARD - Initiative BR-UK-CA, University of Central Lancashire, Preston, UK
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4
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Hutton D, Fadelalla MG, Kanodia AK, Hossain-Ibrahim K. Choroid plexus and CSF: an updated review. Br J Neurosurg 2021; 36:307-315. [PMID: 33821737 DOI: 10.1080/02688697.2021.1903390] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this article, we review the available literature about the functions of the choroid plexus (ChP), including its basic role in cerebrospinal fluid (CSF) secretion, renewal and absorption. We discuss more recently described, lesser-known functions of the ChP, such as its role in circadian rhythm regulation, chemical and immune surveillance and functional implications of ChP disruption, as occurs in neurodegenerative disorders.
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Affiliation(s)
- Dana Hutton
- Department of Neurosurgery, Ninewells Hospital, Dundee, UK
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5
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Direct Measurement of Cerebrospinal Fluid Production in Mice. Cell Rep 2020; 33:108524. [PMID: 33357428 PMCID: PMC8186543 DOI: 10.1016/j.celrep.2020.108524] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/12/2020] [Accepted: 11/23/2020] [Indexed: 11/23/2022] Open
Abstract
The emerging interest in brain fluid transport has prompted a need for techniques that provide an understanding of what factors regulate cerebrospinal fluid (CSF) production. Here, we describe a methodology for direct quantification of CSF production in awake mice. We measure CSF production by placing a catheter in a lateral ventricle, while physically blocking outflow from the 4th ventricle. Using this methodology, we show that CSF production increases during isoflurane anesthesia, and to a lesser extent with ketamine/xylazine anesthesia, relative to the awake state. Aged mice have reduced CSF production, which is even lower in aged mice overexpressing amyloid-β. Unexpectedly, CSF production in young female mice is 30% higher than in age-matched males. Altogether, the present observations imply that a reduction in CSF production might contribute to the age-related risk of proteinopathies but that the rate of CSF production and glymphatic fluid transport are not directly linked. Liu et al. develop a method for direct quantification of cerebrospinal fluid (CSF) production in awake mice. Using this method, the authors evaluate the effect of brain states, ages, sex, anesthetic types, and amyloid-β burden on CSF production.
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6
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Jiang Y, Wang C, Ma R, Zhao Y, Ma X, Wan J, Li C, Chen F, Fang F, Li M. Aquaporin 1 mediates early responses to osmotic stimuli in endothelial cells via the calmodulin pathway. FEBS Open Bio 2020; 11:75-84. [PMID: 33125833 PMCID: PMC7780103 DOI: 10.1002/2211-5463.13020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/30/2020] [Accepted: 09/07/2020] [Indexed: 01/19/2023] Open
Abstract
The aquaporins (AQPs) are a family of integral membrane proteins which play critical roles in controlling transcellular water movement in various tissues throughout the body. AQP1 helps mediate the cellular response to osmotic stress and tissue water permeability. However, the mechanism by which AQP1 mediates changes in cell volume is not completely clear. Here, we investigated how AQP1 responds to and controls cell volume upon osmotic stimuli during the early phase after the immediate response. Cells overexpressing AQP1 were exposed to hypotonic or hypertonic medium in the presence or absence of staurosporine or W-7 hydrochloride, and fluorescence imaging was performed at 0, 5, 10, and 15 min later. Osmotic stimuli induced redistribution of AQP1 into the cell membrane, hypotonic stimuli caused cell enlargement, and hypertonic stimuli induced a reduction in cell size, which was blocked by T157A/T239A mutations. Changes in cell size induced by osmotic stimuli were blocked by an antagonist of calmodulin kinase, W-7 hydrochloride, but not by the PKC inhibitor staurosporine. These results suggest that calmodulin kinase regulates AQP1 activity during the early response to osmotic stimuli.
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Affiliation(s)
- Yong Jiang
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Chengqi Wang
- Department of Clinical Medicine, Jilin Medical University, China
| | - Rui Ma
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Ying Zhao
- Department of Cardiology, Jilin Central Hospital, China
| | - Xinyue Ma
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Jiaxin Wan
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Chunxiang Li
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Fanghao Chen
- Department of Clinical Medicine, Jilin Medical University, China
| | - Fang Fang
- Department of Laboratory Medicine, Jilin Medical University, China
| | - Mingguang Li
- Department of Laboratory Medicine, Jilin Medical University, China
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7
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Rauen K, Pop V, Trabold R, Badaut J, Plesnila N. Vasopressin V 1a Receptors Regulate Cerebral Aquaporin 1 after Traumatic Brain Injury. J Neurotrauma 2020; 37:665-674. [PMID: 31547764 PMCID: PMC7045352 DOI: 10.1089/neu.2019.6653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Brain edema formation contributes to secondary brain damage and unfavorable outcome after traumatic brain injury (TBI). Aquaporins (AQP), highly selective water channels, are involved in the formation of post-trauma brain edema; however, their regulation is largely unknown. Because vasopressin receptors are involved in AQP-mediated water transport in the kidney and inhibition of V1a receptors reduces post-trauma brain edema formation, we hypothesize that cerebral AQPs may be regulated by V1a receptors. Cerebral Aqp1 and Aqp4 messenger ribonucleic acid (mRNA) and AQP1 and AQP4 protein levels were quantified in wild-type and V1a receptor knockout (V1a-/-) mice before and 15 min, 1, 3, 6, 12, or 24 h after experimental TBI by controlled cortical impact. In non-traumatized mice, we found AQP1 and AQP4 expression in cortical neurons and astrocytes, respectively. Experimental TBI had no effect on Aqp4 mRNA or AQP4 protein expression, but increased Aqp1 mRNA (p < 0.05) and AQP1 protein expression (p < 0.05) in both hemispheres. The Aqp1 mRNA and AQP1 protein regulation was blunted in V1a receptor knockout mice. The V1a receptors regulate cerebral AQP1 expression after experimental TBI, thereby unraveling the molecular mechanism by which these receptors may mediate brain edema formation after TBI.
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Affiliation(s)
- Katrin Rauen
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
- Institute for Stroke and Dementia Research (ISD), University of Munich Medical Center, Munich, Germany
- University Hospital of Psychiatry Zurich, Department of Geriatric Psychiatry & Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
| | - Viorela Pop
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
| | - Raimund Trabold
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
| | - Jerome Badaut
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
- Aquitaine Institute for Cognitive and Integrative Neuroscience, University of Bordeaux, Bordeaux, France
| | - Nikolaus Plesnila
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
- Institute for Stroke and Dementia Research (ISD), University of Munich Medical Center, Munich, Germany
- Munich Cluster for Systems Neurology (Synergy), Munich, Germany
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8
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Physiological and pathological impact of AQP1 knockout in mice. Biosci Rep 2019; 39:BSR20182303. [PMID: 31023968 PMCID: PMC6522737 DOI: 10.1042/bsr20182303] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/21/2019] [Accepted: 04/24/2019] [Indexed: 01/04/2023] Open
Abstract
Aquaporin 1 (AQP1) is a glycoprotein responsible for water passive transport quickly across biological membrane. Here, we reviewed the structural and functional impacts of AQP1 knockout (AQP1-KO) in animal or cell culture models. AQP1 gene deletion can cause a large number of abnormalities including the disturbance in epithelial fluid secretion, polyhydramnios, deficiency of urinary concentrating function, and impairment of pain perception. AQP1-KO mice also displayed aberrations of cardiovascular, gastrointestinal and hepatobiliary, and kidney functions as well as placenta and embryo development. Moreover, AQP1-KO perturbed tumor angiogenesis and led to reduced brain injury upon trauma. On the cellular level, AQP1-KO caused neuroinflammation, aberrant cell proliferation and migration, and macrophages infiltration. Mechanistic studies confirmed that AQP1 gene products regulate the secretory function and participated in balancing the osmotic water flux across the peritoneal membrane. The available data indicated that AQP1 might serve as a potential target for developing novel therapeutic approaches against diverse human diseases.
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9
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Plog BA, Nedergaard M. The Glymphatic System in Central Nervous System Health and Disease: Past, Present, and Future. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2019; 13:379-394. [PMID: 29195051 DOI: 10.1146/annurev-pathol-051217-111018] [Citation(s) in RCA: 428] [Impact Index Per Article: 85.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The central nervous system (CNS) is unique in being the only organ system lacking lymphatic vessels to assist in the removal of interstitial metabolic waste products. Recent work has led to the discovery of the glymphatic system, a glial-dependent perivascular network that subserves a pseudolymphatic function in the brain. Within the glymphatic pathway, cerebrospinal fluid (CSF) enters the brain via periarterial spaces, passes into the interstitium via perivascular astrocytic aquaporin-4, and then drives the perivenous drainage of interstitial fluid (ISF) and its solute. Here, we review the role of the glymphatic pathway in CNS physiology, the factors known to regulate glymphatic flow, and the pathologic processes in which a breakdown of glymphatic CSF-ISF exchange has been implicated in disease initiation and progression. Important areas of future research, including manipulation of glymphatic activity aiming to improve waste clearance and therapeutic agent delivery, are also discussed.
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Affiliation(s)
- Benjamin A Plog
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642, USA; , .,Department of Pathology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642, USA; ,
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10
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Kant S, Stopa EG, Johanson CE, Baird A, Silverberg GD. Choroid plexus genes for CSF production and brain homeostasis are altered in Alzheimer's disease. Fluids Barriers CNS 2018; 15:34. [PMID: 30541599 PMCID: PMC6291926 DOI: 10.1186/s12987-018-0120-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 12/03/2018] [Indexed: 11/10/2022] Open
Abstract
Background The roles of the choroid plexus (CP) and cerebrospinal fluid (CSF) production have drawn increasing attention in Alzheimer’s disease (AD) research. Specifically, studies document markedly decreased CSF production and turnover in moderate-to-severe AD. Moreover, reduced CP function and CSF turnover lead to impaired clearance of toxic metabolites, likely promote neuroinflammation, and may facilitate neuronal death during AD progression. We analyzed CP gene expression in AD compared with control subjects, specifically considering those genes involved with CSF production and CP structural integrity. Methods The Brown-Merck Gene Expression Omnibus (GEO) database (CP transcripts) was mined to examine changes in gene expression in AD compared to controls with a focus on assorted genes thought to play a role in CSF production. Specifically, genes coding for ion transporters in CP epithelium (CPE) and associated enzymes like Na–K-ATPase and carbonic anhydrase, aquaporins, mitochondrial transporters/enzymes, blood–cerebrospinal fluid barrier (BCSFB) stability proteins, and pro-inflammatory mediators were selected for investigation. Data were analyzed using t test p-value and fold-change analysis conducted by the GEO2R feature of the GEO database. Results Significant expression changes for several genes were observed in AD CP. These included disruptions to ion transporters (e.g., the solute carrier gene SLC4A5, p = 0.004) and associated enzyme expressions (e.g., carbonic anhydrase CA4, p = 0.0001), along with decreased expression of genes involved in BCSFB integrity (e.g., claudin CLDN5, p = 0.039) and mitochondrial ATP synthesis (e.g., adenosine triphosphate ATP5L, p = 0.0004). Together all changes point to disrupted solute transport at the blood–CSF interface in AD. Increased expression of pro-inflammatory (e.g., interleukin IL1RL1, p = 0.00001) and potential neurodegenerative genes (e.g., amyloid precursor APBA3, p = 0.002) also implicate disturbed CP function. Conclusions Because the altered expression of numerous transcripts in AD-CP help explain decreased CSF production in AD, these findings represent a first step towards identifying novel therapeutic targets in AD. Electronic supplementary material The online version of this article (10.1186/s12987-018-0120-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shawn Kant
- Department of Pathology (Neuropathology Division), Warren Alpert Medical School at Brown University, Providence, RI, 02903, USA
| | - Edward G Stopa
- Department of Pathology (Neuropathology Division), Warren Alpert Medical School at Brown University, Providence, RI, 02903, USA
| | - Conrad E Johanson
- Department of Neurosurgery, Warren Alpert Medical School at Brown University, Providence, RI, 02903, USA
| | - Andrew Baird
- Department of Surgery, University of California San Diego, La Jolla, CA, USA
| | - Gerald D Silverberg
- Department of Neurosurgery, Stanford University, 710 Frenchmans Rd, Stanford, CA, 94305, USA.
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11
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Shepard MJ, Padmanaban V, Edwards NA, Chittiboina P, Ray-Chaudhury A, Heiss JD. Discovery of Aquaporin-1 and Aquaporin-4 Expression in an Intramedullary Spinal Cord Ependymal Cyst: Case Report. World Neurosurg 2017; 107:1046.e1-1046.e7. [PMID: 28826713 DOI: 10.1016/j.wneu.2017.07.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Intramedullary ependymal cysts of the spinal cord are rare, benign, fluid-filled cysts usually situated along the ventral surface of the spinal cord. Only 32 cases have been reported since they were first described. Thus, owing to the rarity at which these cysts are encountered, their management and pathogenesis remain controversial. Whereas some investigators have advocated for cystosubarachnoid shunt placement for symptomatic ependymal cysts, others have argued for complete cyst resection or simple fenestration. Here we report the case of a 56-year-old female with a T11-T12 ependymal cyst that was successfully managed with cyst fenestration. We further investigated a potential pathological mechanism of cyst formation by performing immunohistochemistry to detect aquaporin expression in the cyst lining. CASE DESCRIPTION A 56-year-old female was found to harbor an enlarging cystic lesion of the conus that was discovered on workup of progressive paraparesis and urinary incontinence. She had lower extremity weakness and progressive myelopathy. Thoracic laminectomy with cyst fenestration arrested her neurologic deterioration. Pathological analysis revealed an intramedullary ependymal cyst. Immunohistochemistry was subsequently performed for expression of aquaporin-1 and aquaporin-4. There was dense staining of the underlying neuropil with concurrent membranous staining pattern of the cyst lining. CONCLUSIONS Intramedullary ependymal cysts are rare, cystic lesions of the spinal cord. Early cyst fenestration decompresses the cyst and prevents neurologic deterioration. Here we report for the first time that aquaporins are expressed in the cyst wall, which is consistent with a passive, osmotic pathogenic mechanism of cyst formation.
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Affiliation(s)
- Matthew J Shepard
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland; Department of Neurologic Surgery, University of Virginia Health System, Charlottesville, Virginia.
| | - Varun Padmanaban
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland; Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Nancy A Edwards
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Prashant Chittiboina
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland; Neurosurgery Unit for Pituitary and Inheritable Diseases, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Abhik Ray-Chaudhury
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - John D Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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12
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Filippidis AS, Carozza RB, Rekate HL. Aquaporins in Brain Edema and Neuropathological Conditions. Int J Mol Sci 2016; 18:ijms18010055. [PMID: 28036023 PMCID: PMC5297690 DOI: 10.3390/ijms18010055] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/20/2016] [Accepted: 12/20/2016] [Indexed: 01/22/2023] Open
Abstract
The aquaporin (AQP) family of water channels are a group of small, membrane-spanning proteins that are vital for the rapid transport of water across the plasma membrane. These proteins are widely expressed, from tissues such as the renal epithelium and erythrocytes to the various cells of the central nervous system. This review will elucidate the basic structure and distribution of aquaporins and discuss the role of aquaporins in various neuropathologies. AQP1 and AQP4, the two primary aquaporin molecules of the central nervous system, regulate brain water and CSF movement and contribute to cytotoxic and vasogenic edema, where they control the size of the intracellular and extracellular fluid volumes, respectively. AQP4 expression is vital to the cellular migration and angiogenesis at the heart of tumor growth; AQP4 is central to dysfunctions in glutamate metabolism, synaptogenesis, and memory consolidation; and AQP1 and AQP4 adaptations have been seen in obstructive and non-obstructive hydrocephalus and may be therapeutic targets.
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Affiliation(s)
- Aristotelis S Filippidis
- Division of Neurosurgery, Beth Israel Deaconess Medical School, Harvard Medical School, Boston, MA 02115, USA.
- Department of Neurosurgery, Boston Medical Center, Boston University, Boston, MA 02215, USA.
| | | | - Harold L Rekate
- Department of Neurosurgery, The Chiari Institute, Hofstra Northwell School of Medicine, Hempstead, NY 11549, USA.
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miR-320a affects spinal cord edema through negatively regulating aquaporin-1 of blood-spinal cord barrier during bimodal stage after ischemia reperfusion injury in rats. BMC Neurosci 2016; 17:10. [PMID: 26850728 PMCID: PMC4744445 DOI: 10.1186/s12868-016-0243-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/25/2016] [Indexed: 01/19/2023] Open
Abstract
Background Spinal cord edema is a serious complication and pathophysiological change after ischemia reperfusion (IR) injury. It has been demonstrated closely associated with bimodal disruption of blood–spinal cord barrier (BSCB) in our previous work. Aquaporin (AQP)1 plays important but contradictory roles in water homeostasis. Recently, microRNAs (miRs) effectively regulate numerous target mRNAs during ischemia. However, whether miRs are able to protect against dimodal disruption of BSCB by regulating perivascular AQP1 remains to be elucidated.
Results Spinal water content and EB extravasation were suggested as a bimodal distribution in directly proportion to AQP1, since all maximal changes were detected at 12 and 48 h after reperfusion. Further TEM and double immunofluorescence showed that former disruption of BSCB at 12 h was attributed to cytotoxic edema by up-regulated AQP1 expressions in astrocytes, whereas the latter at 48 h was mixed with vasogenic edema with both endothelial cells and astrocytes involvement. Microarray analysis revealed that at 12 h post-injury, ten miRs were upregulated (>2.0 fold) and seven miRs were downregulated (<0.5 fold) and at 48 h, ten miRs were upregulated and eleven were downregulated compared to Sham-operated controls. Genomic screening and luciferase assays identified that miR-320a was a potential modulator of AQP1 in spinal cord after IR in vitro. In vivo, compared to rats in IR and negative control group, intrathecal infusion of miR-320a mimic attenuated IR-induced lower limb motor function deficits and BSCB dysfunction as decreased EB extravasation and spinal water content through down-regulating AQP1 expressions, whereas pretreated with miR-320a AMO reversed above effects.
Conclusion These findings indicate miR-320a directly and functionally affects spinal cord edema through negatively regulating AQP1 of BSCB after IR.
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Hubbard JA, Hsu MS, Seldin MM, Binder DK. Expression of the Astrocyte Water Channel Aquaporin-4 in the Mouse Brain. ASN Neuro 2015; 7:7/5/1759091415605486. [PMID: 26489685 PMCID: PMC4623559 DOI: 10.1177/1759091415605486] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aquaporin-4 (AQP4) is a bidirectional water channel that is found on astrocytes throughout the central nervous system. Expression is particularly high around areas in contact with cerebrospinal fluid, suggesting that AQP4 plays a role in fluid exchange between the cerebrospinal fluid compartments and the brain. Despite its significant role in the brain, the overall spatial and region-specific distribution of AQP4 has yet to be fully characterized. In this study, we used Western blotting and immunohistochemical techniques to characterize AQP4 expression and localization throughout the mouse brain. We observed AQP4 expression throughout the forebrain, subcortical areas, and brainstem. AQP4 protein levels were highest in the cerebellum with lower expression in the cortex and hippocampus. We found that AQP4 immunoreactivity was profuse on glial cells bordering ventricles, blood vessels, and subarachnoid space. Throughout the brain, AQP4 was expressed on astrocytic end-feet surrounding blood vessels but was also heterogeneously expressed in brain tissue parenchyma and neuropil, often with striking laminar specificity. In the cerebellum, we showed that AQP4 colocalized with the proteoglycan brevican, which is synthesized by and expressed on cerebellar astrocytes. Despite the high abundance of AQP4 in the cerebellum, its functional significance has yet to be investigated. Given the known role of AQP4 in synaptic plasticity in the hippocampus, the widespread and region-specific expression pattern of AQP4 suggests involvement not only in fluid balance and ion homeostasis but also local synaptic plasticity and function in distinct brain circuits.
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Affiliation(s)
- Jacqueline A Hubbard
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
| | - Mike S Hsu
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
| | - Marcus M Seldin
- Division of Cardiology, University of California, Los Angeles, CA, USA
| | - Devin K Binder
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
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Jessen NA, Munk ASF, Lundgaard I, Nedergaard M. The Glymphatic System: A Beginner's Guide. Neurochem Res 2015; 40:2583-99. [PMID: 25947369 DOI: 10.1007/s11064-015-1581-6] [Citation(s) in RCA: 1025] [Impact Index Per Article: 113.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/06/2015] [Accepted: 04/10/2015] [Indexed: 12/16/2022]
Abstract
The glymphatic system is a recently discovered macroscopic waste clearance system that utilizes a unique system of perivascular tunnels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system. Besides waste elimination, the glymphatic system also facilitates brain-wide distribution of several compounds, including glucose, lipids, amino acids, growth factors, and neuromodulators. Intriguingly, the glymphatic system function mainly during sleep and is largely disengaged during wakefulness. The biological need for sleep across all species may therefore reflect that the brain must enter a state of activity that enables elimination of potentially neurotoxic waste products, including β-amyloid. Since the concept of the glymphatic system is relatively new, we will here review its basic structural elements, organization, regulation, and functions. We will also discuss recent studies indicating that glymphatic function is suppressed in various diseases and that failure of glymphatic function in turn might contribute to pathology in neurodegenerative disorders, traumatic brain injury and stroke.
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Affiliation(s)
- Nadia Aalling Jessen
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Ave, Box 645, Rochester, NY, 14642, USA.
| | - Anne Sofie Finmann Munk
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Ave, Box 645, Rochester, NY, 14642, USA
| | - Iben Lundgaard
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Ave, Box 645, Rochester, NY, 14642, USA
| | - Maiken Nedergaard
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Ave, Box 645, Rochester, NY, 14642, USA
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Trevisi G, Frassanito P, Di Rocco C. Idiopathic cerebrospinal fluid overproduction: case-based review of the pathophysiological mechanism implied in the cerebrospinal fluid production. Croat Med J 2014; 55:377-87. [PMID: 25165051 PMCID: PMC4157373 DOI: 10.3325/cmj.2014.55.377] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 08/10/2014] [Indexed: 12/15/2022] Open
Abstract
Cerebrospinal fluid (CSF) overproduction results from either CSF infection or choroid plexus hypertrophy or tumor, with only a single idiopathic case described so far. We report a unique case of a male infant with Crouzon syndrome who presented with intracranial hypertension, caused by up to 4-fold increase in CSF daily production. Conditions related to CSF overproduction, namely central nervous system infections and choroid plexus hypertrophy or tumor, were ruled out by repeated magnetic resonance imaging and CSF samples. Medical therapy failed to reduce CSF production and the patient underwent several shunting procedures, cranial expansion, and endoscopic coagulation of the choroid plexus. This article thoroughly reviews pertinent literature on CSF production mechanisms and possible therapeutic implications.
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Affiliation(s)
| | - Paolo Frassanito
- Paolo Frassanito, Pediatric Neurosurgery, Catholic University Medical School, Largo Agostino Gemelli 8, 00168 Rome, Italy,
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17
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Christensen HL, Nguyen AT, Pedersen FD, Damkier HH. Na(+) dependent acid-base transporters in the choroid plexus; insights from slc4 and slc9 gene deletion studies. Front Physiol 2013; 4:304. [PMID: 24155723 PMCID: PMC3804831 DOI: 10.3389/fphys.2013.00304] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 10/02/2013] [Indexed: 02/02/2023] Open
Abstract
The choroid plexus epithelium (CPE) is located in the ventricular system of the brain, where it secretes the majority of the cerebrospinal fluid (CSF) that fills the ventricular system and surrounds the central nervous system. The CPE is a highly vascularized single layer of cuboidal cells with an unsurpassed transepithelial water and solute transport rate. Several members of the slc4a family of bicarbonate transporters are expressed in the CPE. In the basolateral membrane the electroneutral Na+ dependent Cl−/HCO3− exchanger, NCBE (slc4a10) is expressed. In the luminal membrane, the electrogenic Na+:HCO3− cotransporter, NBCe2 (slc4a5) is expressed. The electroneutral Na+:HCO3− cotransporter, NBCn1 (slc4a7), has been located in both membranes. In addition to the bicarbonate transporters, the Na+/H+ exchanger, NHE1 (slc9a1), is located in the luminal membrane of the CPE. Genetically modified mice targeting slc4a2, slc4a5, slc4a7, slc4a10, and slc9a1 have been generated. Deletion of slc4a5, 7 or 10, or slc9a1 has numerous impacts on CP function and structure in these mice. Removal of the transporters affects brain ventricle size (slc4a5 and slc4a10) and intracellular pH regulation (slc4a7 and slc4a10). In some instances, removal of the proteins from the CPE (slc4a5, 7, and 10) causes changes in abundance and localization of non-target transporters known to be involved in pH regulation and CSF secretion. The focus of this review is to combine the insights gathered from these knockout mice to highlight the impact of slc4 gene deletion on the CSF production and intracellular pH regulation resulting from the deletion of slc4a5, 7 and 10, and slc9a1. Furthermore, the review contains a comparison of the described human mutations of these genes to the findings in the knockout studies. Finally, the future perspective of utilizing these proteins as potential targets for the treatment of CSF disorders will be discussed.
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Chang JT, Lowery LA, Sive H. Multiple roles for the Na,K-ATPase subunits, Atp1a1 and Fxyd1, during brain ventricle development. Dev Biol 2012; 368:312-22. [PMID: 22683378 DOI: 10.1016/j.ydbio.2012.05.034] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 05/29/2012] [Accepted: 05/29/2012] [Indexed: 01/26/2023]
Abstract
Formation of the vertebrate brain ventricles requires both production of cerebrospinal fluid (CSF), and its retention in the ventricles. The Na,K-ATPase is required for brain ventricle development, and we show here that this protein complex impacts three associated processes. The first requires both the alpha subunit (Atp1a1) and the regulatory subunit, Fxyd1, and leads to formation of a cohesive neuroepithelium, with continuous apical junctions. The second process leads to modulation of neuroepithelial permeability, and requires Atp1a1, which increases permeability with partial loss of function and decreases it with overexpression. In contrast, fxyd1 overexpression does not alter neuroepithelial permeability, suggesting that its activity is limited to neuroepithelium formation. RhoA regulates both neuroepithelium formation and permeability, downstream of the Na,K-ATPase. A third process, likely to be CSF production, is RhoA-independent, requiring Atp1a1, but not Fxyd1. Consistent with a role for Na,K-ATPase pump function, the inhibitor ouabain prevents neuroepithelium formation, while intracellular Na(+) increases after Atp1a1 and Fxyd1 loss of function. These data include the first reported role for Fxyd1 in the developing brain, and indicate that the Na,K-ATPase regulates three aspects of brain ventricle development essential for normal function: formation of a cohesive neuroepithelium, restriction of neuroepithelial permeability, and production of CSF.
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Affiliation(s)
- Jessica T Chang
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, United States
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Kim J, Jung Y. Increased aquaporin-1 and Na+ -K+ -2Cl- cotransporter 1 expression in choroid plexus leads to blood-cerebrospinal fluid barrier disruption and necrosis of hippocampal CA1 cells in acute rat models of hyponatremia. J Neurosci Res 2012; 90:1437-44. [PMID: 22419034 DOI: 10.1002/jnr.23017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 11/21/2011] [Accepted: 12/02/2011] [Indexed: 12/13/2022]
Abstract
Hyponatremia is a metabolic disorder characterized by increased cerebrospinal fluid (CSF) volume and pressure, although the site of brain insult is unclear. Specifically, the hippocampus, which is in direct contact with expanding CSF ventricles, may be involved. The present study was undertaken to investigate the possible roles of choroid plexus aquaporin-1 (AQP1) and of cation chloride transporters (Na(+) -K(+) -2Cl(-) cotransporter 1 [NKCC1] and K(+) -Cl(-) cotransporter 4 [KCC4]) in the underlying hippocampal pathophysiology of hyponatremia in acute (6 and 12 hr duration) experimental models. It was found that the expressions of AQP1 and NKCC1 proteins in choroid plexus were significantly increased, whereas the expression of KCC4 protein was unchanged vs. control values after 6 and 12 hr of hyponatremia. Choroid plexuses with increased AQP1 and NKCC1 after 6 hr of hyponatremia showed caspase 3-dependent apoptosis and disruption of the blood-CSF barrier. Furthermore, necrotic changes in CA1 neuronal cells were observed after 6 and 12 hr of hyponatremia. Overall, these data suggest that increases in AQP1 and NKCC1 expression under hyposmotic stress may be one of the molecular mechanisms underlying the pathophysiology of acute hyponatremia, such as the necrotic cell death of hippocampal CA1 region by increasing water transport across the blood-CSF barrier. Furthermore, we suggest that opening of the blood-CSF barrier after acute hyponatremia may be triggered the secondary adverse conditions that are capable of enhancing selective necrosis in hippocampal CA1 cells.
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Affiliation(s)
- Jaehyun Kim
- Department of Anatomy, College of Medicine, Dongguk University, Gyeongju, Republic of Korea
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Fossdal G, Vik-Mo EO, Sandberg C, Varghese M, Kaarbø M, Telmo E, Langmoen IA, Murrell W. Aqp 9 and brain tumour stem cells. ScientificWorldJournal 2012; 2012:915176. [PMID: 22262958 PMCID: PMC3259507 DOI: 10.1100/2012/915176] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 10/08/2011] [Indexed: 01/01/2023] Open
Abstract
Several studies have implicated the aquaporins (aqp) 1, 4, and 9 in the pathogenesis of malignant brain tumours, suggesting that they contribute to motility, invasiveness, and oedema formation and facilitate metabolism in tumour cells under hypoxic conditions. We have studied the expression of aqp1, 4, and 9 in biopsies from glioblastomas, isolated tumour stem cells grown in a tumoursphere assay and analyzed the progenitor and differentiated cells from these cultures. We have compared these to the situation in normal rat brain, its stem cells, and differentiated cells derived thereof. In short, qPCR in tumour tissue showed presence of aqp1, 4, and 9. In the tumour progenitor population, aqp9 was markedly more highly expressed, whilst in tumour-derived differentiated cells, aqp4 was downregulated. However, immunostaining did not reveal increased protein expression of aqp9 in the tumourspheres containing progenitor cells; in contrast, its expression (both mRNA and protein) was high in differentiated cultures. We, therefore, propose that aquaporin 9 may have a central role in the tumorigenesis of glioblastoma.
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Affiliation(s)
- Guri Fossdal
- Vilhelm Magnus laboratory, Institute for Surgical Research, Norwegian National Hospital, Oslo University Hospital, 0450 Oslo, Norway
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21
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Ameli PA, Madan M, Chigurupati S, Yu A, Chan SL, Pattisapu JV. Effect of acetazolamide on aquaporin-1 and fluid flow in cultured choroid plexus. ACTA NEUROCHIRURGICA. SUPPLEMENT 2012; 113:59-64. [PMID: 22116425 DOI: 10.1007/978-3-7091-0923-6_13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Acetazolamide (AZA), used in treatment of early or infantile hydrocephalus, is effective in some cases, while its effect on the choroid plexus (CP) remains ill-defined. The drug reversibly inhibits aquaporin-4 (AQP4), the most ubiquitous "water pore" in the brain, and perhaps modulation of AQP1 (located apically on CP cells) by AZA may reduce cerebrospinal fluid (CSF) production. We sought to elucidate the effect of AZA on AQP1 and fluid flow in CP cell cultures.CP tissue culture from 10-day Sprague-Dawley rats and a TRCSF-B cell line were grown on Transwell permeable supports and treated with 100 μM AZA. Fluid assays to assess direction and extent of fluid flow, and AQP1 expression patterns by immunoblot, Immuncytochemistry (ICC), and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) were performed.Immunoblots and ICC analyses showed a decrease in AQP1 protein shortly after AZA treatment (lowest at 12 h), with transient AQP1 reduction mediated by mRNA expression (lowest at 6 h). Transwell fluid assays indicated a fluid shift at 2 h, before significant changes in AQP1 mRNA or protein levels.Timing of AZA effect on AQP1 suggests the drug alters protein transcription, while affecting fluid flow by a concomitant method. It is plausible that other mechanisms account for these phenomena, as the processes may occur independently.
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Affiliation(s)
- Pouya A Ameli
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
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22
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Kalani MYS, Filippidis AS, Rekate HL. Hydrocephalus and aquaporins: the role of aquaporin-1. ACTA NEUROCHIRURGICA. SUPPLEMENT 2012; 113:51-4. [PMID: 22116423 DOI: 10.1007/978-3-7091-0923-6_11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
INTRODUCTION Aquaporins (AQPs) are membrane proteins that facilitate water and small solute movement in tissues. Hydrocephalus is a major central nervous system disorder associated with defective cerebrospinal fluid (CSF) turnover. Aquaporin-1 (AQP1) is a water channel located mainly at the choroid plexus epithelium and plays an active role in CSF production. The aim of this study is to review the pertinent literature concerning the role of aquaporin-1 in the pathophysiology of hydrocephalus. METHODS We performed a MEDLINE search using the terms aquaporin AND hydrocephalus. The results of the search were further refined to exclude studies not related to aquaporin-1. RESULTS Five studies were identified. Three of these studies utilized an animal model, while only two studies referred to a few human cases of hydrocephalus. Most of the studies indicate that there is a down-regulation of AQP1 expression in choroid plexus in models of hydrocephalus. A small series of human choroid plexus tumors showed that AQP1 expression is up-regulated. In cases of human choroid plexus tumors, there are indications that AQP1 may have alternative physiologic roles, but it is not clear whether this is associated with a specific type of hydrocephalus or the genetic burden of the tumor. CONCLUSION There has been a paucity of research on the link between aquaporins and hydrocephalus. Most studies have relied on animal models. An adaptive and protective role of AQP1 as a regulator of CSF production is proposed in the pathophysiology of hydrocephalus. Further research is needed to clarify if this association exists in humans.
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Affiliation(s)
- M Y S Kalani
- St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
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Kim J, Jung Y. Different expressions of AQP1, AQP4, eNOS, and VEGF proteins in ischemic versus non-ischemic cerebropathy in rats: potential roles of AQP1 and eNOS in hydrocephalic and vasogenic edema formation. Anat Cell Biol 2011; 44:295-303. [PMID: 22254158 PMCID: PMC3254883 DOI: 10.5115/acb.2011.44.4.295] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 10/18/2011] [Accepted: 12/06/2011] [Indexed: 11/27/2022] Open
Abstract
In this study, expressions of aquaporin (AQP) 1, AQP4, endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor in blood-cerebrospinal fluid (CSF) barrier and blood-brain barrier (BBB) are examined in rat choroid plexus and peri-infarcted hippocampal formation (HF) following systemic hyponatremia (SH) and permanent middle cerebral artery occlusion (pMCAO). These events are thought to cause the development of hydrocephalic and vasogenic edemas. The importance of CSF overproduction and intact blood-CSF barrier during hydrocephalic edema formation is demonstrated by the high expression of AQP1 (329.86±10.2%, n=4 , P<0.01) and trapped plasma immunoglobulin G (IgG) in choroid plexus epithelium after 24 hours of SH. However, the increased eNOS expression in peri-infarcted HF (130±3%, n=4, P<0.01) and extravasation of plasma IgG into the extravascular compartment after 24 hours of pMCAO suggest that increased microvascular permeability, probably due to elevated levels of nitric oxide, leads to development of vasogenic brain edema via BBB breakdown. Based on these findings, the authors suggest that modulation of different protein expression, dependent on the type of brain edema, is required for primary (pMCAO) and secondary (SH) brain injuries to attenuate brain edema and neuronal degeneration.
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Affiliation(s)
- Jaehyun Kim
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, Korea
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Surash S, Nemeth P, Chakrabarty A, Chumas P. The conjugation of an AQP1-directed immunotoxin in the study of site-directed therapy within the CNS. Childs Nerv Syst 2011; 27:811-8. [PMID: 21104258 DOI: 10.1007/s00381-010-1336-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 11/09/2010] [Indexed: 11/28/2022]
Abstract
PURPOSE The water channel, aquaporin (AQP)1, is highly specific to the choroid plexus (CP) epithelium within the brain. It is therefore a potential target through which therapeutic agents could be selectively directed to the CP. Here we describe the conjugation of a monoclonal antibody (mAb), raised against an extra-cellular domain of AQP1, to the A chain of ricin (RCA). This reagent should allow study of a highly specific chemical lesion of the CP. METHODS A published method was used to couple the anti-AQP1 mAb to the A chain of ricin using an SPDP cross-linker. The conjugate was purified by Superdex S-200 chromatography. Column fractions were analysed by SDS-PAGE and Western blotting. Fractions containing conjugate were assayed for cytotoxicity on rat CP cells in culture, using a WST-1 viability assay to assess cell death. RESULTS SDS-PAGE and Western blotting demonstrated separation of conjugated anti-AQP1 mAb from unconjugated ricin by the Superdex column. Cultured rat CP cells were killed with an IC(50) of 1.81 μg/ml when exposed to the anti-AQP1 mAb-RCA conjugation reaction products. Selectivity of this reagent was demonstrated by the higher IC(50) exhibited by non-AQP1-expressing primary fibroblast cultures and cultures exposed to the reaction products from the non-specific IgG-RCA conjugation attempt. CONCLUSION We have been able to demonstrate selective cytotoxicity in vitro of an anti-AQP1 mAb-RCA conjugate. We hope that this work will generate further interest in the use of this site-specific conjugate to target the CP in conditions such as hydrocephalus, tumours that arise from here, and other AQP1-expressing tumours.
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Affiliation(s)
- Surash Surash
- Department of Neurosurgery, The General Infirmary at Leeds, Great George Street, Leeds, LS1 3EX, UK.
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Yeo SI, Ryu HJ, Kim JE, Chun W, Seo CH, Lee BC, Choi IG, Sheen SH, Kang TC. The effects of electrical shock on the expressions of aquaporin subunits in the rat spinal cords. Anat Cell Biol 2011; 44:50-9. [PMID: 21519549 PMCID: PMC3080008 DOI: 10.5115/acb.2011.44.1.50] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 12/22/2010] [Accepted: 12/27/2010] [Indexed: 11/27/2022] Open
Abstract
We analyzed aquaporin (AQP) expression in the rat spinal cord following an electrical shock (ES) to elucidate the roles of AQP in spinal cord injury (SCI) induced by an electrical burn. In control animals, AQP1 immunoreactivity was observed in the small diameter dorsal horn fibers of laminae I and II and in astrocytes and neurons in the spinal cord. Both AQP4 and AQP9 immunoreactivity were detected in astrocytes. One week after the ES, AQP1 immunoreactivity in dorsal horn fibers was downregulated to 83, 61, and 33% of control levels following a 1-, 4-, or 6-second ES, respectively. However, AQP1 immunoreactivity in ventral horn neurons increased to 1.3-, 1.5-, and 2.4-fold of control levels following a 1-, 4-, or 6-second ES, respectively. AQP4 immunoreactivity was upregulated after an ES in laminae I and II astrocytes in a stimulus-intensity independent manner. Unlike AQP1 and AQP4, AQP9 immunoreactivity was unaffected by the ES. These findings indicate that altered AQP immunoreactivity may be involved in SCI following an ES.
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Affiliation(s)
- Seong-Il Yeo
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chuncheon, Korea
- Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, Korea
| | - Hea Jin Ryu
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chuncheon, Korea
- Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, Korea
| | - Ji-Eun Kim
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chuncheon, Korea
- Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, Korea
| | - Wook Chun
- Department of Surgery, Hangang Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Korea
| | - Cheong Hoon Seo
- Department of Rehabilitation, Hangang Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Korea
| | - Boung Chul Lee
- Department of Psychiatry, Hangang Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Korea
| | - Ihn-Geun Choi
- Department of Psychiatry, Hangang Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Korea
| | - Seung Hun Sheen
- Department of Neurosurgery, Graduate School, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Tae-Cheon Kang
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chuncheon, Korea
- Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, Korea
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Aquaporin expression in the brains of patients with or without cerebral amyloid angiopathy. J Neuropathol Exp Neurol 2010; 69:1201-9. [PMID: 21107133 DOI: 10.1097/nen.0b013e3181fd252c] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Aquaporins have recently been identified as protein channels involved in water transport. These channels may play a role in the edema formation and alterations in microvascular function observed in Alzheimer disease (AD) and cerebral amyloid angiopathy (CAA). We investigated the expression of aquaporin 1 (AQP1) and aquaporin 4 (AQP4) in 24 human autopsy brains consisting of 18 with AD and varying degrees of CAA and 6 with no pathologic abnormalities using immunohistochemistry. In cases of AD and CAA, there was enhanced AQP4 expression compared with the age- and sex-matched controls. Aquaporin 4 immunoreactivity was prominent at the cerebrospinal fluid and brain interfaces, including subpial, subependymal, pericapillary, and periarteriolar spaces. Aquaporin 1 expression in AD and CAA cases was not different from that in age- and sex-matched controls. Double labeling studies demonstrated that both AQP1 and 4 were localized to astrocytes. Both enhanced AQP4 expression and its unique staining pattern suggest that these proteins may be important in the impaired water transport observed in AD and CAA.
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27
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Zelenina M. Regulation of brain aquaporins. Neurochem Int 2010; 57:468-88. [DOI: 10.1016/j.neuint.2010.03.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/21/2010] [Accepted: 03/31/2010] [Indexed: 01/27/2023]
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Xu GY, Wang F, Jiang X, Tao J. Aquaporin 1, a potential therapeutic target for migraine with aura. Mol Pain 2010; 6:68. [PMID: 20969805 PMCID: PMC2974658 DOI: 10.1186/1744-8069-6-68] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 10/25/2010] [Indexed: 11/10/2022] Open
Abstract
The pathophysiology of migraine remains largely unknown. However, evidence regarding the molecules participating in the pathophysiology of migraine has been accumulating. Water channel proteins, known as aquaporins (AQPs), notably AQP-1 and AQP-4, appears to be involved in the pathophysiology of several neurological diseases. This review outlines newly emerging evidence indicating that AQP-1 plays an important role in pain signal transduction and migraine and could therefore serve as a potential therapeutic target for these diseases.
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Affiliation(s)
- Guang-Yin Xu
- Key Laboratory of Pain Research & Therapy, Department of Neurobiology and Institute of Neuroscience, Soochow University, Suzhou, P.R. China
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A preliminary study of aquaporin 1 immunolocalization in chronic subdural hematoma membranes. J Clin Neurosci 2010; 17:905-7. [PMID: 20409716 DOI: 10.1016/j.jocn.2009.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 11/05/2009] [Accepted: 11/08/2009] [Indexed: 11/21/2022]
Abstract
Aquaporin 1 (AQP1) is a molecular water channel expressed in many anatomical locations, particularly in epithelial barriers specialized in water transport. The aim of this study was to investigate AQP1 expression in chronic subdural hematoma (CSDH) membranes. In this preliminary study, 11 patients with CSDH underwent burr hole craniectomy and drainage. Membrane specimens were stained with a monoclonal antibody targeting AQP1 for immunohistochemical analysis. The endothelial cells of the sinusoid capillaries of the outer membranes exhibited an elevated immunoreactivity to AQP1 antibody compared to the staining intensity of specimens from the inner membrane and normal dura. These findings suggest that the outer membrane might be the source of the increased fluid accumulation responsible for chronic hematoma enlargement.
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Johanson CE, Duncan JA, Klinge PM, Brinker T, Stopa EG, Silverberg GD. Multiplicity of cerebrospinal fluid functions: New challenges in health and disease. Cerebrospinal Fluid Res 2008; 5:10. [PMID: 18479516 PMCID: PMC2412840 DOI: 10.1186/1743-8454-5-10] [Citation(s) in RCA: 514] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 05/14/2008] [Indexed: 11/10/2022] Open
Abstract
UNLABELLED This review integrates eight aspects of cerebrospinal fluid (CSF) circulatory dynamics: formation rate, pressure, flow, volume, turnover rate, composition, recycling and reabsorption. Novel ways to modulate CSF formation emanate from recent analyses of choroid plexus transcription factors (E2F5), ion transporters (NaHCO3 cotransport), transport enzymes (isoforms of carbonic anhydrase), aquaporin 1 regulation, and plasticity of receptors for fluid-regulating neuropeptides. A greater appreciation of CSF pressure (CSFP) is being generated by fresh insights on peptidergic regulatory servomechanisms, the role of dysfunctional ependyma and circumventricular organs in causing congenital hydrocephalus, and the clinical use of algorithms to delineate CSFP waveforms for diagnostic and prognostic utility. Increasing attention focuses on CSF flow: how it impacts cerebral metabolism and hemodynamics, neural stem cell progression in the subventricular zone, and catabolite/peptide clearance from the CNS. The pathophysiological significance of changes in CSF volume is assessed from the respective viewpoints of hemodynamics (choroid plexus blood flow and pulsatility), hydrodynamics (choroidal hypo- and hypersecretion) and neuroendocrine factors (i.e., coordinated regulation by atrial natriuretic peptide, arginine vasopressin and basic fibroblast growth factor). In aging, normal pressure hydrocephalus and Alzheimer's disease, the expanding CSF space reduces the CSF turnover rate, thus compromising the CSF sink action to clear harmful metabolites (e.g., amyloid) from the CNS. Dwindling CSF dynamics greatly harms the interstitial environment of neurons. Accordingly the altered CSF composition in neurodegenerative diseases and senescence, because of adverse effects on neural processes and cognition, needs more effective clinical management. CSF recycling between subarachnoid space, brain and ventricles promotes interstitial fluid (ISF) convection with both trophic and excretory benefits. Finally, CSF reabsorption via multiple pathways (olfactory and spinal arachnoidal bulk flow) is likely complemented by fluid clearance across capillary walls (aquaporin 4) and arachnoid villi when CSFP and fluid retention are markedly elevated. A model is presented that links CSF and ISF homeostasis to coordinated fluxes of water and solutes at both the blood-CSF and blood-brain transport interfaces. OUTLINE 1 Overview2 CSF formation2.1 Transcription factors2.2 Ion transporters2.3 Enzymes that modulate transport2.4 Aquaporins or water channels2.5 Receptors for neuropeptides3 CSF pressure3.1 Servomechanism regulatory hypothesis3.2 Ontogeny of CSF pressure generation3.3 Congenital hydrocephalus and periventricular regions3.4 Brain response to elevated CSF pressure3.5 Advances in measuring CSF waveforms4 CSF flow4.1 CSF flow and brain metabolism4.2 Flow effects on fetal germinal matrix4.3 Decreasing CSF flow in aging CNS4.4 Refinement of non-invasive flow measurements5 CSF volume5.1 Hemodynamic factors5.2 Hydrodynamic factors5.3 Neuroendocrine factors6 CSF turnover rate6.1 Adverse effect of ventriculomegaly6.2 Attenuated CSF sink action7 CSF composition7.1 Kidney-like action of CP-CSF system7.2 Altered CSF biochemistry in aging and disease7.3 Importance of clearance transport7.4 Therapeutic manipulation of composition8 CSF recycling in relation to ISF dynamics8.1 CSF exchange with brain interstitium8.2 Components of ISF movement in brain8.3 Compromised ISF/CSF dynamics and amyloid retention9 CSF reabsorption9.1 Arachnoidal outflow resistance9.2 Arachnoid villi vs. olfactory drainage routes9.3 Fluid reabsorption along spinal nerves9.4 Reabsorption across capillary aquaporin channels10 Developing translationally effective models for restoring CSF balance11 Conclusion.
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Affiliation(s)
- Conrad E Johanson
- Department of Clinical Neurosciences, Warren Alpert Medical School at Brown University, Providence, RI 02903, USA
| | - John A Duncan
- Department of Clinical Neurosciences, Warren Alpert Medical School at Brown University, Providence, RI 02903, USA
| | - Petra M Klinge
- International Neuroscience Institute Hannover, Rudolph-Pichlmayr-Str. 4, 30625 Hannover, Germany
| | - Thomas Brinker
- International Neuroscience Institute Hannover, Rudolph-Pichlmayr-Str. 4, 30625 Hannover, Germany
| | - Edward G Stopa
- Department of Clinical Neurosciences, Warren Alpert Medical School at Brown University, Providence, RI 02903, USA
| | - Gerald D Silverberg
- Department of Clinical Neurosciences, Warren Alpert Medical School at Brown University, Providence, RI 02903, USA
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Nesic O, Lee J, Unabia GC, Johnson K, Ye Z, Vergara L, Hulsebosch CE, Perez-Polo JR. Aquaporin 1 - a novel player in spinal cord injury. J Neurochem 2008; 105:628-40. [PMID: 18248364 DOI: 10.1111/j.1471-4159.2007.05177.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The role of water channel aquaporin 1 (AQP-1) in uninjured or injured spinal cords is unknown. AQP-1 is weakly expressed in neurons and gray matter astrocytes, and more so in white matter astrocytes in uninjured spinal cords, a novel finding. As reported before, AQP-1 is also present in ependymal cells, but most abundantly in small diameter sensory fibers of the dorsal horn. Rat contusion spinal cord injury (SCI) induced persistent and significant four- to eightfold increases in AQP-1 levels at the site of injury (T10) persisting up to 11 months post-contusion, a novel finding. Delayed AQP-1 increases were also found in cervical and lumbar segments, suggesting the spreading of AQP-1 changes over time after SCI. Given that the antioxidant melatonin significantly decreased SCI-induced AQP-1 increases and that hypoxia inducible factor-1alpha was increased in acutely and chronically injured spinal cords, we propose that chronic hypoxia contributes to persistent AQP-1 increases after SCI. Interestingly; AQP-1 levels were not affected by long-lasting hypertonicity that significantly increased astrocytic AQP-4, suggesting that the primary role of AQP-1 is not regulating isotonicity in spinal cords. Based on our results we propose possible novel roles for AQP-1 in the injured spinal cords: (i) in neuronal and astrocytic swelling, as AQP-1 was increased in all surviving neurons and reactive astrocytes after SCI and (ii) in the development of the neuropathic pain after SCI. We have shown that decreased AQP-1 in melatonin-treated SCI rats correlated with decreased AQP-1 immunolabeling in the dorsal horns sensory afferents, and with significantly decreased mechanical allodynia, suggesting a possible link between AQP-1 and chronic neuropathic pain after SCI.
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Affiliation(s)
- O Nesic
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1072, USA.
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Zador Z, Bloch O, Yao X, Manley GT. Aquaporins: role in cerebral edema and brain water balance. PROGRESS IN BRAIN RESEARCH 2007; 161:185-94. [PMID: 17618977 DOI: 10.1016/s0079-6123(06)61012-1] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The regulation of water balance in the brain is crucial. A disruption in this equilibrium causes an increase in brain water content that significantly contributes to the pathophysiology of traumatic brain injury, hydrocephalus, and a variety of neurological disorders. The discovery of the aquaporin (AQP) family of membrane water channels has provided important new insights into the physiology and pathology of brain water homeostasis. A number of recent studies are described in the review that demonstrated the important role of AQP1 and AQP4 in brain water balance and cerebral edema. Phenotypic analyses of AQP deficient mice have allowed us to explore the role of these membrane water channels in the mechanisms of cytotoxic edema, vasogenic edema, and CSF production. These studies indicate that AQP4 plays significant role in the development of cytotoxic edema and the absorption of excess brain water resulting from vasogenic edema. They also have demonstrated the role of AQP1 in CSF production and maintenance of steady-state ICP. The ability to modulate water flux through AQP deletion has provided new insights into brain water homeostasis and suggested a number of new research directions. However, these efforts have not yet translated to the treatment human clinical diseases. These advances will require the development of AQP inhibitors and activators to establish the benefit modulating the function of these water channels.
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Affiliation(s)
- Zsolt Zador
- Department of Neurological Surgery, Brain and Spinal Injury Center, University of California, San Francisco, CA 94110, USA
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Praetorius J. Water and solute secretion by the choroid plexus. Pflugers Arch 2006; 454:1-18. [PMID: 17120021 DOI: 10.1007/s00424-006-0170-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Accepted: 09/12/2006] [Indexed: 12/23/2022]
Abstract
The cerebrospinal fluid (CSF) provides mechanical and chemical protection of the brain and spinal cord. This review focusses on the contribution of the choroid plexus epithelium to the water and salt homeostasis of the CSF, i.e. the secretory processes involved in CSF formation. The choroid plexus epithelium is situated in the ventricular system and is believed to be the major site of CSF production. Numerous studies have identified transport processes involved in this secretion, and recently, the underlying molecular background for some of the mechanisms have emerged. The nascent CSF consists mainly of NaCl and NaHCO(3), and the production rate is strictly coupled to the rate of Na(+) secretion. In contrast to other secreting epithelia, Na(+) is actively pumped across the luminal surface by the Na(+),K(+)-ATPase with possible contributions by other Na(+) transporters, e.g. the luminal Na(+),K(+),2Cl(-) cotransporter. The Cl(-) and HCO(3) (-) ions are likely transported by a luminal cAMP activated inward rectified anion conductance, although the responsible proteins have not been identified. Whereas Cl(-) most likely enters the cells through anion exchange, the functional as well as the molecular basis for the basolateral Na(+) entry are not yet well-defined. Water molecules follow across the epithelium mainly through the water channel, AQP1, driven by the created ionic gradient. In this article, the implications of the recent findings for the current model of CSF secretion are discussed. Finally, the clinical implications and the prospects of future advances in understanding CSF production are briefly outlined.
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Affiliation(s)
- Jeppe Praetorius
- The Water and Salt Research Center & Institute of Anatomy, University of Aarhus, Wilhelm Meyers Allé, 8000 Aarhus, Denmark.
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Iandiev I, Pannicke T, Biedermann B, Wiedemann P, Reichenbach A, Bringmann A. Ischemia-reperfusion alters the immunolocalization of glial aquaporins in rat retina. Neurosci Lett 2006; 408:108-12. [PMID: 16997459 DOI: 10.1016/j.neulet.2006.08.084] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/16/2006] [Accepted: 08/25/2006] [Indexed: 01/26/2023]
Abstract
Glial cells control the retinal osmohomeostasis, in part via mediation of water fluxes through aquaporin (AQP) water channels. By using immunohistochemical staining, we investigated whether ischemia-reperfusion of the rat retina causes alterations in the distribution of AQP1 and AQP4 proteins. Transient ischemia was induced in retinas of Long-Evans rats by elevation of the intraocular pressure for 60 min. In control retinas, immunoreactive AQP1 was expressed in the outer retina and by distinct amacrine cells, and AQP4 was expressed by glial cells (Müller cells and astrocytes) predominantly in the inner retina. After ischemia, retinal glial cells in the nerve fiber/ganglion cell layers strongly expressed AQP1. The perivascular staining around the superficial vessels altered from AQP4 in control retinas to AQP1 in postischemic retinas. The data suggest that the glial cell-mediated water transport in the retina is altered after ischemia especially at the superficial vessel plexus.
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Affiliation(s)
- Ianors Iandiev
- Paul Flechsig Institute of Brain Research, University of Leipzig Medical Faculty, 04109 Leipzig, Germany
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Abstract
The meninges comprise the dura mater and the leptomeninges (arachnoid and pia mater). Dura forms an outer endosteal layer related to the bones of the skull and spine and an inner layer closely applied to the arachnoid mater. Leptomeninges have multiple functions and anatomical relationships. The outer parietal layer of arachnoid is impermeable to CSF due to tight intercellular junctions; elsewhere leptomeningeal cells form demosomes and gap junctions. Trabeculae of leptomeninges compartmentalize the subarachnoid space and join the pia to arachnoid mater. In bacterial meningitis leptomeningeal cells secrete cytokines. Pia mater is reflected from the surface of the brain and spinal cord onto arteries and veins, thus separating the subarachnoid space from the brain and cord. A sheath of leptomeninges accompanies arteries into the brain and is related to the pathways for the drainage of interstitial fluid that play a role in inflammatory responses in the brain and appear to be blocked by amyloid-beta in Alzheimer's disease. Specialised leptomeningeal cells in the stroma of the choroid plexus form collagen whorls that become calcified with age. Leptomeningeal cells also form channels in the core and apical cap of arachnoid granulations for the drainage of CSF into venous sinuses. In the spine, leptomeninges form highly perforated intermediate sheets of arachnoid and delicate ligaments that compartmentalize the subarachnoid space; dentate ligaments anchor subpial collagen to the dura mater and stabilize the spinal cord. Despite the multiple anatomical arrangements and physiological functions, leptomeningeal cells retain many histological features that are similar from site to site.
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Affiliation(s)
- R O Weller
- Clinical Neurosciences, Southampton University School of Medicine, Mail Point 813, Southampton General Hospital, Southampton SO16 6YD, UK.
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Praetorius J, Nielsen S. Distribution of sodium transporters and aquaporin-1 in the human choroid plexus. Am J Physiol Cell Physiol 2006; 291:C59-67. [PMID: 16481371 DOI: 10.1152/ajpcell.00433.2005] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The choroid plexus epithelium secretes electrolytes and fluid in the brain ventricular lumen at high rates. Several channels and ion carriers have been identified as likely mediators of this transport in rodent choroid plexus. This study aimed to map several of these proteins to the human choroid plexus. Immunoperoxidase-histochemistry was employed to determine the cellular and subcellular localization of the proteins. The water channel, aquaporin (AQP) 1, was predominantly situated in the apical plasma membrane domain, although distinct basolateral and endothelial immunoreactivity was also observed. The Na(+)-K(+)-ATPase alpha(1)-subunit was exclusively localized apically in the human choroid plexus epithelial cells. Immunoreactivity for the Na(+)-K(+)-2Cl(-) cotransporter, NKCC1, was likewise confined to the apical plasma membrane domain of the epithelium. The Cl(-)/HCO(3)(-) exchanger, AE2, was localized basolaterally, as was the Na(+)-dependent Cl(-)/HCO(3)(-) exchanger, NCBE, and the electroneutral Na(+)-HCO(3)(-) cotransporter, NBCn1. No immunoreactivity was found toward the Na(+)-dependent acid/base transporters NHE1 or NBCe2. Hence, the human choroid plexus epithelium displays an almost identical distribution pattern of water channels and Na(+) transporters as the rat and mouse choroid plexus. This general cross species pattern suggests central roles for these transporters in choroid plexus functions such as cerebrospinal fluid production.
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Affiliation(s)
- Jeppe Praetorius
- The Water and Salt Research Center, Institute of Anatomy, Univ. of Aarhus, Wilhelm Meyers Allé, Bldg. 234, 8000 Aarhus C, Denmark.
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Longatti P, Basaldella L, Orvieto E, Dei Tos A, Martinuzzi A. Aquaporin(s) expression in choroid plexus tumours. Pediatr Neurosurg 2006; 42:228-33. [PMID: 16714863 DOI: 10.1159/000092359] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Accepted: 10/21/2005] [Indexed: 11/19/2022]
Abstract
OBJECTIVE It was the aim of this study to investigate the pattern of aquaporin 1 (AQP1) expression in normal and neoplastic choroid plexus, with specific reference to the association with communicating hydrocephalus or liquoral cysts. Second, to infer a new view on the cerebrospinal fluid plexus production and on the etiology of the cysts and communicating hydrocephalus occasionally associated with choroid plexus papillomas. MATERIALS AND METHODS Nineteen paraffin-embedded specimens, 10 of normal choroid plexus and 9 of choroid plexus tumours, were immunostained with a monoclonal antibody raised against the intracellular C-terminal AQP1 epitope. Results were analysed in terms of intensity and intracellular distribution of immunostaining and in terms of number of stained cells; they were considered in light of the clinical association with hydrocephalus or liquoral cysts. RESULTS AQP1 was heavily expressed in the apical side of the choroid epithelium in normal plexus specimens. Choroid plexus papillomas showed a very heterogeneous pattern of AQP1 expression. Immunostaining was absent in the case of choroid plexus carcinoma. Very strong to strong and diffuse AQP1 expression in large to very large papillomas was associated with liquoral cysts or communicating hydrocephalus. CONCLUSIONS AQP1 expression characterizes normal choroid plexus and plexus papillomas. Intensity and diffusion of AQP1 expression together with the size of the tumour mass are somewhat predictive of communicating hydrocephalus or liquoral cyst, lesions possibly caused by a disturbance of cerebrospinal fluid homeostasis.
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Moon Y, Hong SJ, Shin D, Jung Y. Increased aquaporin-1 expression in choroid plexus epithelium after systemic hyponatremia. Neurosci Lett 2005; 395:1-6. [PMID: 16293370 DOI: 10.1016/j.neulet.2005.10.060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 10/08/2005] [Accepted: 10/16/2005] [Indexed: 10/25/2022]
Abstract
The expression of aquaporin-1 (AQP1) protein, a water channel, in the choroid plexus epithelium was examined in the rat to determine the role of AQP1 in the pathophysiology of systemic hyponatremia. Systemic hyponatremia was produced by coadministration of 30 ml hypotonic dextrose solution (140 mM) intraperitoneally and 3 microg 1-deamino-8-d-arginine vasopressin (dDAVP) subcutaneously. This hydration protocol produced severe systemic hyponatremia: 2h after drug administration, normonatremic serum osmolarity and Na(+) concentration (296+/-5mOsm/L and 140+/-5 mM) were reduced to 252+/-5mOsm/L and 117+/-2 mM, respectively. AQP1 expression in the third ventricle choroid plexus epithelium was determined by using immunohistochemistry and quantitative immunoblot analysis. After 2h of systemic hyponatremia, AQP1 expression was significantly increased by 28.2+/-2.7% (n=6, P<0.05), whereas it was attenuated to 15.7+/-2.2% (n=6, P<0.05) after 6h of systemic hyponatremia. In addition, TUNEL staining revealed apoptotic granule cells in the dentate gyrus (DG) adjacent to the third ventricle with a peak measured 2h after the start of the systemic hyponatremia protocol, while virtually no apoptotic granule cells left 6h after the start of the hyponatremic treatment. These findings suggest that AQP1-mediated excessive water influx into the brain through the blood-cerebrospinal fluid barrier during systemic hyponatremia may elevate the intracranial pressure and result in the apoptotic brain cell death. Thus, AQP1 in the choroid plexus may play an important role in the pathogenesis of systemic hyponatremia.
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Affiliation(s)
- Yongsuk Moon
- Department of Anatomy, School of Medicine, Catholic University of Daegu, 3056-6 Daemyung-Dong, Daegu 705-718, Republic of Korea
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Amiry-Moghaddam M, Lindland H, Zelenin S, Roberg BA, Gundersen BB, Petersen P, Rinvik E, Torgner IA, Ottersen OP. Brain mitochondria contain aquaporin water channels: evidence for the expression of a short AQP9 isoform in the inner mitochondrial membrane. FASEB J 2005; 19:1459-67. [PMID: 16126913 DOI: 10.1096/fj.04-3515com] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aquaporins are a family of water channels found in animals, plants, and microorganisms. A subfamily of aquaporins, the aquaglyceroporins, are permeable for water as well as certain solutes such as glycerol, lactate, and urea. Here we show that the brain contains two isoforms of AQP9--an aquaglyceroporin with a particularly broad substrate specificity--and that the more prevalent of these isoforms is expressed in brain mitochondria. The mitochondrial AQP9 isoform is detected as an approximately 25 kDa band in immunoblots. This isoform is likely to correspond to a new AQP9 mRNA that is obtained by alternative splicing and has a shorter ORF than the liver isoform. Subfractionation experiments and high-resolution immunogold analyses revealed that this novel AQP9 isoform is enriched in mitochondrial inner membranes. AQP9 immunopositive mitochondria occurred in astrocytes throughout the brain and in a subpopulation of neurons in the substantia nigra, ventral tegmental area, and arcuate nucleus. In the latter structures, the AQP9 immunopositive mitochondria were located in neurons that were also immunopositive for tyrosine hydroxylase, as demonstrated by double labeling immunogold electron microscopy. Our findings suggest that mitochondrial AQP9 is a hallmark of astrocytes and midbrain dopaminergic neurons. In physiological conditions, the flux of lactate and other metabolites through AQP9 may confer an advantage by allowing the mitochondria to adjust to the metabolic status of the extramitochondrial cytoplasm. We hypothesize that the complement of mitochondrial AQP9 in dopaminergic neurons may relate to the vulnerability of these neurons in Parkinson's disease.
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Affiliation(s)
- Mahmood Amiry-Moghaddam
- Centre for Molecular Biology and Neuroscience, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
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Abstract
Birth is a transition from an underwater life in the uterus to a terrestrial life in a milieu where supply of water is limited. Rapid adaptation to the new environment is crucial for survival and health of infants. The discovery of a family of molecules-aquaporin (AQP) water channels-that are responsible for regulated water transport across cell membranes has made it possible to identify the molecular mechanisms behind the postnatal homeostatic adaptation and to better understand water imbalance-related disorders in infancy and childhood. Thirteen mammalian AQP isoforms have been identified, most of them having a unique tissue-specific pattern of expression. Most mammalian AQPs can be dynamically regulated, which makes them potential targets for the development of new drugs for diseases associated with disturbances in water homeostasis. This review deals with AQP in kidney, lung, and brain. Evidence is presented that AQPs are expressed in a specific age-dependent manner and that the timed expression of AQPs may have a crucial role during the early postnatal period.
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Affiliation(s)
- Marina Zelenina
- Nordic Center of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
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Emerich DF, Skinner SJM, Borlongan CV, Vasconcellos AV, Thanos CG. The choroid plexus in the rise, fall and repair of the brain. Bioessays 2005; 27:262-74. [PMID: 15714561 DOI: 10.1002/bies.20193] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The choroid plexuses (CPs) are involved in the most-basic aspects of neural function including maintaining the extracellular milieu of the brain by actively modulating chemical exchange between the CSF and brain parenchyma, surveying the chemical and immunological status of the brain, detoxifying the brain, secreting a nutritive "cocktail" of polypeptides and participating in repair processes following trauma. This diversity of functions may mean that even modest changes in the CP can have far-reaching effects. Indeed, changes in the anatomy and physiology of the CP have been linked to aging and several CNS diseases. It is also possible that replacing diseased or transplanting healthy CP might be useful for treating acute and chronic brain diseases. This review focuses on the wide-ranging and under-appreciated functions of the CP, alterations of these functions in aging and neurodegeneration, and recent demonstrations of the therapeutic potential of transplanted CP for neural trauma.
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Papadopoulos MC, Saadoun S, Binder DK, Manley GT, Krishna S, Verkman AS. Molecular mechanisms of brain tumor edema. Neuroscience 2005; 129:1011-20. [PMID: 15561416 DOI: 10.1016/j.neuroscience.2004.05.044] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Revised: 05/24/2004] [Accepted: 05/25/2004] [Indexed: 10/26/2022]
Abstract
Despite their diverse histological types, most brain tumours cause brain oedema, which is a significant cause of patient morbidity and mortality. Brain tumour oedema occurs when plasma-like fluid enters the brain extracellular space through impaired capillary endothelial tight junctions in tumours. Under-expression of the tight junction proteins occludin, claudin-1 and claudin-5 are key molecular abnormalities responsible for the increased permeability of tumour endothelial tight junctions. Recent evidence suggests that the membrane water channel protein aquaporin-4 (AQP4) also plays a role in brain tumour oedema. AQP4-deficient mice show remarkably altered brain water balance after various insults, including brain tumour implantation. AQP4 expression is strongly upregulated around malignant human brain tumours in association with reduced extracellular volume, which may restrict the flow of extracellular fluid from the tumour bed into the brain parenchyma. Elimination of excess fluid leaking into brain parenchyma requires passage across three AQP4-rich barriers: a) the glia limitans externa, b) the glia limitans interna/ependyma, and c) the blood-brain barrier. Modulation of the expression and/or function of endothelial tight junction proteins and aquaporins may provide novel therapeutic options for reducing brain tumour oedema.
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Affiliation(s)
- M C Papadopoulos
- Department of Neurosurgery, St. George's Hospital Medical School, London SW17 0NE, UK.
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Brown PD, Davies SL, Speake T, Millar ID. Molecular mechanisms of cerebrospinal fluid production. Neuroscience 2005; 129:957-70. [PMID: 15561411 PMCID: PMC1890044 DOI: 10.1016/j.neuroscience.2004.07.003] [Citation(s) in RCA: 287] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2004] [Indexed: 11/23/2022]
Abstract
The epithelial cells of the choroid plexuses secrete cerebrospinal fluid (CSF), by a process which involves the transport of Na(+), Cl(-) and HCO(3)(-) from the blood to the ventricles of the brain. The unidirectional transport of ions is achieved due to the polarity of the epithelium, i.e. the ion transport proteins in the blood-facing (basolateral) membrane are different to those in the ventricular (apical) membrane. The movement of ions creates an osmotic gradient which drives the secretion of H(2)O. A variety of methods (e.g. isotope flux studies, electrophysiological, RT-PCR, in situ hybridization and immunocytochemistry) have been used to determine the expression of ion transporters and channels in the choroid plexus epithelium. Most of these transporters have now been localized to specific membranes. For example, Na(+)-K(+)ATPase, K(+) channels and Na(+)-2Cl(-)-K(+) cotransporters are expressed in the apical membrane. By contrast the basolateral membrane contains Cl(-)- HCO(3) exchangers, a variety of Na(+) coupled HCO(3)(-) transporters and K(+)-Cl(-) cotransporters. Aquaporin 1 mediates water transport at the apical membrane, but the route across the basolateral membrane is unknown. A model of CSF secretion by the mammalian choroid plexus is proposed which accommodates these proteins. The model also explains the mechanisms by which K(+) is transported from the CSF to the blood.
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Affiliation(s)
- P D Brown
- School of Biological Sciences, G.38 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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Longatti PL, Basaldella L, Orvieto E, Fiorindi A, Carteri A. Choroid plexus and aquaporin-1: a novel explanation of cerebrospinal fluid production. Pediatr Neurosurg 2004; 40:277-83. [PMID: 15821358 DOI: 10.1159/000083740] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Accepted: 09/15/2004] [Indexed: 11/19/2022]
Abstract
Aquaporins are selective water channel proteins that play a central role in the homeostasis of human body water. The choroid plexus (CP) is considered to be the main cerebrospinal fluid (CSF)-producing structure. In this study, six specimens of normal human CP obtained during surgery were analyzed by immunohistochemistry techniques for aquaporin-1 (AQP1) expression and distribution. Intense, uniformly distributed AQP1 immunostaining was observable in the apical but not the basolateral side of cuboid cells of the CP. Moreover, this polarized expression of AQP1 was weakly detectable in the endothelial cells of choroid microvessels and, with a different pattern, in the cells lining the tubules shaped into crypts. Selective AQP1 expression on the surface of the normal human CP might explain the role of CSF production by this complex structure.
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Affiliation(s)
- P L Longatti
- Department of Neurosurgery, Treviso Hospital, University of Padua, Italy.
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Schrier RW, Chen YC, Cadnapaphornchai MA. From finch to fish to man: Role of aquaporins in body fluid and brain water regulation. Neuroscience 2004; 129:897-904. [PMID: 15561406 DOI: 10.1016/j.neuroscience.2004.06.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2004] [Indexed: 11/28/2022]
Abstract
Charles Darwin, in his Origin of the Species, noted that different species of finches on the Galapagos Islands had adapted their beak size based on where they sought their food. Homer Smith, in his book From Fish to Philosopher, discussed the evolution of the nephron from a single conduit in salt water vertebrates, to nephrons with large glomerular capillaries and proximal and distal tubules in fresh water vertebrates, to smaller glomerular capillaries in amphibians, to nephrons with loops of Henle to allow for urinary concentration and dilution in mammals. The kidney with its million nephrons has emerged as the vital organ for regulating body fluid composition and volume. With the recent discovery of aquaporin water channels, our understanding of volume regulation has been greatly enhanced. This article reviews current knowledge regarding: 1) the unifying hypothesis of body fluid volume regulation; 2) brain aquaporins and their role in pathophysiologic states; and 3) function and regulation of renal aquaporins in the syndrome of inappropriate antidiuretic hormone secretion (SIADH).
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Affiliation(s)
- R W Schrier
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, 4200 East 9th Avenue, Box B173, Denver, CO 80262, USA.
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Abstract
Emerging evidence suggests that brain aquaporins (AQP) play important roles for the dynamic regulation of brain water homeostasis and for the regulation of cerebrospinal fluid production. This review deals with the short- and long-term regulation of AQP4 and AQP9, both expressed in astrocytes, and of AQP1, expressed in the choroid plexus. AQP1 and 4 have in other cell types been shown to be regulated by phosphorylation. Phosphorylation affects the gating of AQP4 and the trafficking and insertion into membrane of AQP1. Mercury inhibits the water permeability of AQP1 and AQP9, but not AQP4. The permeability of AQP4 is increased by lead. AQP4 is also regulated by protein-protein interaction. The assembly between AQP4 and syntrophin is required for the proper localization of AQP4 in the astrocyte plasma membrane that faces capillaries. There is evidence from studies on peripheral tissues that steroid hormones regulate the expression of AQP1, AQP4 and AQP9. There is also evidence that the expression of AQP1 can be regulated by ubiquitination, and that osmolality can regulate the expression of AQP1, AQP4 and AQP9. Further insight into the mechanisms by which brain AQPs are regulated will be of utmost clinical importance, since perturbed water flow via brain AQPs has been implicated in many neurological diseases and since, in brain edema, water flow via AQP4 may have a harmful effect.
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Affiliation(s)
- E Gunnarson
- Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
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