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Ohbuchi M, Shibuta M, Tetsuka K, Sasaki-Iwaoka H, Oishi M, Shimizu F, Nagasaka Y. Modeling of Blood-Brain Barrier (BBB) Dysfunction and Immune Cell Migration Using Human BBB-on-a-Chip for Drug Discovery Research. Int J Mol Sci 2024; 25:6496. [PMID: 38928202 PMCID: PMC11204321 DOI: 10.3390/ijms25126496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
Blood-brain barrier (BBB) dysfunction is a key feature in neuroimmunological and neurodegenerative diseases. In this study, we developed a microfluidic human BBB-on-a-chip to model barrier dysfunction and immune cell migration using immortalized TY10 brain endothelial cells, pericytes, and astrocytes. It was found that immortalized TY10 brain endothelial cells developed a microvascular structure under flow. Pericytes were localized on the basal side surrounding the TY10 microvascular structure, showing an in vivo-like structure. Barrier integrity increased under co-culture with pericytes. In addition, both ethylenediaminetetraacetic acid (EDTA) and anti-Claudin-5 (CLDN5) neutralizing antibody caused a decrease in the transendothelial electrical resistance (TEER). EDTA caused the leakage of 20 kDa dextran, suggesting different effects on the BBB based on the mechanism of action, whereas anti-CLDN5 antibody did not cause leakage. In the tri-culture model, human T cells migrated through endothelial vessels towards basal C-X-C motif chemokine ligand 12 (CXCL12). The live-imaging analysis confirmed the extravasation of fluorescence-labelled T cells in a CXCL12-concentration- and time-dependent manner. Our BBB model had an in vivo-like structure and successfully represented barrier dysfunction and transendothelial T cell migration. In addition, our study suggests that the inhibition of CLDN5 attenuates the BBB in humans. This platform has various potential uses in relation to the BBB in both drug discovery research and in elucidating the mechanisms of central nervous system diseases.
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Affiliation(s)
- Masato Ohbuchi
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
| | - Mayu Shibuta
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
| | - Kazuhiro Tetsuka
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
| | - Haruna Sasaki-Iwaoka
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
| | - Masayo Oishi
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
| | - Fumitaka Shimizu
- Department of Neurology and Clinical Neuroscience, Graduate School of Medicine, Yamaguchi University, Ube 755-8505, Yamaguchi, Japan;
| | - Yasuhisa Nagasaka
- Applied Research & Operations, Astellas Pharma Inc., Tsukuba 305-8585, Ibaraki, Japan; (M.S.); (K.T.); (H.S.-I.); (M.O.); (Y.N.)
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Establishing Co-Culture Blood–Brain Barrier Models for Different Neurodegeneration Conditions to Understand Its Effect on BBB Integrity. Int J Mol Sci 2023; 24:ijms24065283. [PMID: 36982361 PMCID: PMC10049378 DOI: 10.3390/ijms24065283] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/03/2023] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
The blood–brain barrier (BBB) is a functional interface that provides selective permeability, protection from toxic substances, transport of nutrients, and clearance of brain metabolites. Additionally, BBB disruption has been shown to play a role in many neurodegenerative conditions and diseases. Therefore, the aim of this study was to establish a functional, convenient, and efficient in vitro co-cultured BBB model that can be used for several physiological conditions related to BBB disruption. Mouse brain-derived endothelial (bEnd.3) and astrocyte (C8-D1A) cells were co-cultured on transwell membranes to establish an intact and functional in vitro model. The co-cultured model and its effects on different neurological diseases and stress conditions, including Alzheimer’s disease (AD), neuroinflammation, and obesity, have been examined by transendothelial electrical resistance (TEER), fluorescein isothiocyanate (FITC) dextran, and tight junction protein analyses. Scanning electron microscope images showed evidence of astrocyte end-feet processes passing through the membrane of the transwell. Moreover, the co-cultured model showed effective barrier properties in the TEER, FITC, and solvent persistence and leakage tests when compared to the mono-cultured model. Additionally, the immunoblot results showed that the expression of tight junction proteins such as zonula occludens-1 (ZO-1), claudin-5, and occludin-1 was enhanced in the co-culture. Lastly, under disease conditions, the BBB structural and functional integrity was decreased. The present study demonstrated that the co-cultured in vitro model mimicked the BBB’s structural and functional integrity and, under disease conditions, the co-cultured model showed similar BBB damages. Therefore, the present in vitro BBB model can be used as a convenient and efficient experimental tool to investigate a wide range of BBB-related pathological and physiological studies.
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3
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Adams Y, Jensen AR. Cerebral malaria - modelling interactions at the blood-brain barrier in vitro. Dis Model Mech 2022; 15:275963. [PMID: 35815443 PMCID: PMC9302004 DOI: 10.1242/dmm.049410] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The blood–brain barrier (BBB) is a continuous endothelial barrier that is supported by pericytes and astrocytes and regulates the passage of solutes between the bloodstream and the brain. This structure is called the neurovascular unit and serves to protect the brain from blood-borne disease-causing agents and other risk factors. In the past decade, great strides have been made to investigate the neurovascular unit for delivery of chemotherapeutics and for understanding how pathogens can circumvent the barrier, leading to severe and, at times, fatal complications. One such complication is cerebral malaria, in which Plasmodium falciparum-infected red blood cells disrupt the barrier function of the BBB, causing severe brain swelling. Multiple in vitro models of the BBB are available to investigate the mechanisms underlying the pathogenesis of cerebral malaria and other diseases. These range from single-cell monolayer cultures to multicellular BBB organoids and highly complex cerebral organoids. Here, we review the technologies available in malaria research to investigate the interaction between P. falciparum-infected red blood cells and the BBB, and discuss the advantages and disadvantages of each model. Summary: This Review discusses the available in vitro models to investigate the impact of adhesion of Plasmodium falciparum-infected red blood cells on the blood–brain barrier, a process associated with cerebral malaria.
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Affiliation(s)
- Yvonne Adams
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Anja Ramstedt Jensen
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
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Archie SR, Al Shoyaib A, Cucullo L. Blood-Brain Barrier Dysfunction in CNS Disorders and Putative Therapeutic Targets: An Overview. Pharmaceutics 2021; 13:pharmaceutics13111779. [PMID: 34834200 PMCID: PMC8622070 DOI: 10.3390/pharmaceutics13111779] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/15/2021] [Accepted: 10/20/2021] [Indexed: 01/22/2023] Open
Abstract
The blood-brain barrier (BBB) is a fundamental component of the central nervous system (CNS). Its functional and structural integrity is vital to maintain the homeostasis of the brain microenvironment by controlling the passage of substances and regulating the trafficking of immune cells between the blood and the brain. The BBB is primarily composed of highly specialized microvascular endothelial cells. These cells’ special features and physiological properties are acquired and maintained through the concerted effort of hemodynamic and cellular cues from the surrounding environment. This complex multicellular system, comprising endothelial cells, astrocytes, pericytes, and neurons, is known as the neurovascular unit (NVU). The BBB strictly controls the transport of nutrients and metabolites into brain parenchyma through a tightly regulated transport system while limiting the access of potentially harmful substances via efflux transcytosis and metabolic mechanisms. Not surprisingly, a disruption of the BBB has been associated with the onset and/or progression of major neurological disorders. Although the association between disease and BBB disruption is clear, its nature is not always evident, specifically with regard to whether an impaired BBB function results from the pathological condition or whether the BBB damage is the primary pathogenic factor prodromal to the onset of the disease. In either case, repairing the barrier could be a viable option for treating and/or reducing the effects of CNS disorders. In this review, we describe the fundamental structure and function of the BBB in both healthy and altered/diseased conditions. Additionally, we provide an overview of the potential therapeutic targets that could be leveraged to restore the integrity of the BBB concomitant to the treatment of these brain disorders.
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Affiliation(s)
- Sabrina Rahman Archie
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; (S.R.A.); (A.A.S.)
| | - Abdullah Al Shoyaib
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; (S.R.A.); (A.A.S.)
| | - Luca Cucullo
- Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Correspondence: ; Tel.: +1-248-370-3884; Fax: +1-248-370-4060
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5
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The Blood-Brain Barrier: Much More Than a Selective Access to the Brain. Neurotox Res 2021; 39:2154-2174. [PMID: 34677787 DOI: 10.1007/s12640-021-00431-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/30/2021] [Accepted: 10/15/2021] [Indexed: 12/15/2022]
Abstract
The blood-brain barrier is a dynamic structure, collectively referred to as the neurovascular unit. It is responsible for the exchange of blood, oxygen, ions, and other molecules between the peripheral circulation and the brain compartment. It is the main entrance to the central nervous system and as such critical for the maintenance of its homeostasis. Dysfunction of the blood-brain barrier is a characteristic of several neurovascular pathologies. Moreover, physiological changes, environmental factors, nutritional habits, and psychological stress can modulate the tightness of the barrier. In this contribution, we summarize our current understanding of structure and function of this important component of the brain. We also describe the neurological deficits associated with its damage. A special emphasis is placed in the effect of the exposure to xenobiotics and pollutants in the permeability of the barrier. Finally, current protective strategies as well as the culture models to study this fascinating structure are discussed.
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6
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Molecular Dambusters: What Is Behind Hyperpermeability in Bradykinin-Mediated Angioedema? Clin Rev Allergy Immunol 2021; 60:318-347. [PMID: 33725263 PMCID: PMC7962090 DOI: 10.1007/s12016-021-08851-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2021] [Indexed: 02/08/2023]
Abstract
In the last few decades, a substantial body of evidence underlined the pivotal role of bradykinin in certain types of angioedema. The formation and breakdown of bradykinin has been studied thoroughly; however, numerous questions remained open regarding the triggering, course, and termination of angioedema attacks. Recently, it became clear that vascular endothelial cells have an integrative role in the regulation of vessel permeability. Apart from bradykinin, a great number of factors of different origin, structure, and mechanism of action are capable of modifying the integrity of vascular endothelium, and thus, may participate in the regulation of angioedema formation. Our aim in this review is to describe the most important permeability factors and the molecular mechanisms how they act on endothelial cells. Based on endothelial cell function, we also attempt to explain some of the challenging findings regarding bradykinin-mediated angioedema, where the function of bradykinin itself cannot account for the pathophysiology. By deciphering the complex scenario of vascular permeability regulation and edema formation, we may gain better scientific tools to be able to predict and treat not only bradykinin-mediated but other types of angioedema as well.
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Shafi R, Poublanc J, Venkatraghavan L, Crawley AP, Sobczyk O, McKetton L, Bayley M, Chandra T, Foster E, Ruttan L, Comper P, Tartaglia MC, Tator CH, Duffin J, Mutch WA, Fisher J, Mikulis DJ. A Promising Subject-Level Classification Model for Acute Concussion Based on Cerebrovascular Reactivity Metrics. J Neurotrauma 2020; 38:1036-1047. [PMID: 33096952 DOI: 10.1089/neu.2020.7272] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Concussion imaging research has primarily focused on neuronal disruption with lesser emphasis directed toward vascular dysfunction. However, blood flow metrics may be more sensitive than measures of neuronal integrity. Vascular dysfunction can be assessed by measuring cerebrovascular reactivity (CVR)-the change in cerebral blood flow per unit change in vasodilatory stimulus. CVR metrics, including speed and magnitude of flow responses to a standardized well-controlled vasoactive stimulus, are potentially useful for assessing individual subjects following concussion given that blood flow dysregulation is known to occur with traumatic brain injury. We assessed changes in CVR metrics to a standardized vasodilatory stimulus during the acute phase of concussion. Using a case control design, 20 concussed participants and 20 healthy controls (HCs) underwent CVR assessment measuring blood oxygen-level dependent (BOLD) magnetic resonance imaging using precise changes in end-tidal partial pressure of CO2 (PETCO2). Metrics were calculated for the whole brain, gray matter (GM), and white matter (WM) using sex-stratification. A leave-one-out receiver operating characteristic (ROC) analysis classified concussed from HCs based on CVR metrics. CVR magnitude was greater and speed of response faster in concussed participants relative to HCs, with WM showing higher classification accuracy compared with GM. ROC analysis for WM-CVR metrics revealed an area under the curve of 0.94 in males and 0.90 in females for speed and magnitude of response respectively. These greater than normal responses to a vasodilatory stimulus warrant further investigation to compare the predictive ability of CVR metrics against structural injury metrics for diagnosis and prognosis in acute concussion.
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Affiliation(s)
- Reema Shafi
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Lashmi Venkatraghavan
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Adrian P Crawley
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Olivia Sobczyk
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Larissa McKetton
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Mark Bayley
- Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Tharshini Chandra
- Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Evan Foster
- Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Lesley Ruttan
- Graduate Department of Psychological Clinical Science, University of Toronto, Toronto, Ontario, Canada.,Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada.,Canadian Concussion Center, Toronto Western Hospital, Toronto, Ontario, Canada
| | - Paul Comper
- Rehabilitation Sciences Institute, University of Toronto, Toronto, Ontario, Canada.,Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Maria Carmela Tartaglia
- Department of Medicine (Neurology), University of Toronto, Toronto, Ontario, Canada.,Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Tanz Center for Research in Neurodegenerative Diseases, Toronto, Ontario, Canada.,Canadian Concussion Center, Toronto Western Hospital, Toronto, Ontario, Canada
| | - Charles H Tator
- Department of Surgery, University of Toronto, Toronto, Ontario, Canada.,Canadian Concussion Center, Toronto Western Hospital, Toronto, Ontario, Canada
| | - James Duffin
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - W Alan Mutch
- Department of Anesthesiology, Perioperative and Pain Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Joseph Fisher
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.,Canadian Concussion Center, Toronto Western Hospital, Toronto, Ontario, Canada
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8
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Giorgi FS, Galgani A, Puglisi-Allegra S, Limanaqi F, Busceti CL, Fornai F. Locus Coeruleus and neurovascular unit: From its role in physiology to its potential role in Alzheimer's disease pathogenesis. J Neurosci Res 2020; 98:2406-2434. [PMID: 32875628 DOI: 10.1002/jnr.24718] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/26/2020] [Accepted: 08/08/2020] [Indexed: 12/15/2022]
Abstract
Locus coeruleus (LC) is the main noradrenergic (NA) nucleus of the central nervous system. LC degenerates early during Alzheimer's disease (AD) and NA loss might concur to AD pathogenesis. Aside from neurons, LC terminals provide dense innervation of brain intraparenchymal arterioles/capillaries, and NA modulates astrocyte functions. The term neurovascular unit (NVU) defines the strict anatomical/functional interaction occurring between neurons, glial cells, and brain vessels. NVU plays a fundamental role in coupling the energy demand of activated brain regions with regional cerebral blood flow, it includes the blood-brain barrier (BBB), plays an active role in neuroinflammation, and participates also to the glymphatic system. NVU alteration is involved in AD pathophysiology through several mechanisms, mainly related to a relative oligoemia in activated brain regions and impairment of structural and functional BBB integrity, which contributes also to the intracerebral accumulation of insoluble amyloid. We review the existing data on the morphological features of LC-NA innervation of the NVU, as well as its contribution to neurovascular coupling and BBB proper functioning. After introducing the main experimental data linking LC with AD, which have repeatedly shown a key role of neuroinflammation and increased amyloid plaque formation, we discuss the potential mechanisms by which the loss of NVU modulation by LC might contribute to AD pathogenesis. Surprisingly, thus far not so many studies have tested directly these mechanisms in models of AD in which LC has been lesioned experimentally. Clarifying the interaction of LC with NVU in AD pathogenesis may disclose potential therapeutic targets for AD.
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Affiliation(s)
- Filippo Sean Giorgi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.,Neurology Unit, Pisa University Hospital, Pisa, Italy
| | | | | | - Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.,I.R.C.C.S. I.N.M. Neuromed, Pozzilli, Italy
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9
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Stofkova A, Murakami M. Neural activity regulates autoimmune diseases through the gateway reflex. Bioelectron Med 2019; 5:14. [PMID: 32232103 PMCID: PMC7098223 DOI: 10.1186/s42234-019-0030-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/18/2019] [Indexed: 12/15/2022] Open
Abstract
The brain, spinal cord and retina are protected from blood-borne compounds by the blood-brain barrier (BBB), blood-spinal cord barrier (BSCB) and blood-retina barrier (BRB) respectively, which create a physical interface that tightly controls molecular and cellular transport. The mechanical and functional integrity of these unique structures between blood vessels and nervous tissues is critical for maintaining organ homeostasis. To preserve the stability of these barriers, interplay between constituent barrier cells, such as vascular endothelial cells, pericytes, glial cells and neurons, is required. When any of these cells are defective, the barrier can fail, allowing blood-borne compounds to encroach neural tissues and cause neuropathologies. Autoimmune diseases of the central nervous system (CNS) and retina are characterized by barrier disruption and the infiltration of activated immune cells. Here we review our recent findings on the role of neural activity in the regulation of these barriers at the vascular endothelial cell level in the promotion of or protection against the development of autoimmune diseases. We suggest nervous system reflexes, which we named gateway reflexes, are fundamentally involved in these diseases. Although their reflex arcs are not completely understood, we identified the activation of specific sensory neurons or receptor cells to which barrier endothelial cells respond as effectors that regulate gateways for immune cells to enter the nervous tissue. We explain this novel mechanism and describe its role in neuroinflammatory conditions, including models of multiple sclerosis and posterior autoimmune uveitis.
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Affiliation(s)
- Andrea Stofkova
- 1Department of Physiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- 2Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-0815 Japan
| | - Masaaki Murakami
- 2Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-0815 Japan
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10
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Stone NL, England TJ, O'Sullivan SE. A Novel Transwell Blood Brain Barrier Model Using Primary Human Cells. Front Cell Neurosci 2019; 13:230. [PMID: 31244605 PMCID: PMC6563620 DOI: 10.3389/fncel.2019.00230] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/08/2019] [Indexed: 01/28/2023] Open
Abstract
Structural alterations and breakdown of the blood brain barrier (BBB) is often a primary or secondary consequence of disease, resulting in brain oedema and the transport of unwanted substances into the brain. It is critical that effective in vitro models are developed to model the in vivo environment to aid in clinically relevant research, especially regarding drug screening and permeability studies. Our novel model uses only primary human cells and includes four of the key cells of the BBB: astrocytes, pericytes, brain microvascular endothelial cells (HBMEC) and neurons. We show that using a larger membrane pore size (3.0 μM) there is an improved connection between the endothelial cells, astrocytes and pericytes. Compared to a two and three cell model, we show that when neurons are added to HBMECs, astrocytes and pericytes, BBB integrity was more sensitive to oxygen-glucose deprivation evidenced by increased permeability and markers of cell damage. Our data also show that a four cell model responds faster to the barrier tightening effects of glucocorticoid dexamethasone, when compared to a two cell and three cell model. These data highlight the important role that neurons play in response to ischaemia, particularly how they contribute to BBB maintenance and breakdown. We consider that this model is more representative of the interactions at the neurovascular unit than other transwell models and is a useful method to study BBB physiology.
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Affiliation(s)
- Nicole L Stone
- Division of Medical Sciences and Graduate Entry Medicine, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Timothy J England
- Division of Medical Sciences and Graduate Entry Medicine, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Saoirse E O'Sullivan
- Division of Medical Sciences and Graduate Entry Medicine, School of Medicine, University of Nottingham, Nottingham, United Kingdom
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11
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Lochhead JJ, Ronaldson PT, Davis TP. Hypoxic Stress and Inflammatory Pain Disrupt Blood-Brain Barrier Tight Junctions: Implications for Drug Delivery to the Central Nervous System. AAPS JOURNAL 2017; 19:910-920. [PMID: 28353217 DOI: 10.1208/s12248-017-0076-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/15/2017] [Indexed: 02/08/2023]
Abstract
A functional blood-brain barrier (BBB) is necessary to maintain central nervous system (CNS) homeostasis. Many diseases affecting the CNS, however, alter the functional integrity of the BBB. It has been shown that various diseases and physiological stressors can impact the BBB's ability to selectively restrict passage of substances from the blood to the brain. Modifications of the BBB's permeability properties can potentially contribute to the pathophysiology of CNS diseases and result in altered brain delivery of therapeutic agents. Hypoxia and/or inflammation are central components of a number of diseases affecting the CNS. A number of studies indicate hypoxia or inflammatory pain increase BBB paracellular permeability, induce changes in the expression and/or localization of tight junction proteins, and affect CNS drug uptake. In this review, we look at what is currently known with regard to BBB disruption following a hypoxic or inflammatory insult in vivo. Potential mechanisms involved in altering tight junction components at the BBB are also discussed. A more detailed understanding of the mediators involved in changing BBB functional integrity in response to hypoxia or inflammatory pain could potentially lead to new treatments for CNS diseases with hypoxic or inflammatory components. Additionally, greater insight into the mechanisms involved in TJ rearrangement at the BBB may lead to novel strategies to pharmacologically increase delivery of drugs to the CNS.
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Affiliation(s)
| | | | - Thomas P Davis
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA.
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12
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Urayama A, Grubb JH, Sly WS, Banks WA. Pharmacologic manipulation of lysosomal enzyme transport across the blood-brain barrier. J Cereb Blood Flow Metab 2016; 36:476-86. [PMID: 26661222 PMCID: PMC4794098 DOI: 10.1177/0271678x15614589] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 09/24/2015] [Indexed: 12/22/2022]
Abstract
The adult blood-brain barrier, unlike the neonatal blood-brain barrier, does not transport lysosomal enzymes into brain, making enzyme replacement therapy ineffective in treating the central nervous system symptoms of lysosomal storage diseases. However, enzyme transport can be re-induced with alpha-adrenergics. Here, we examined agents that are known to alter the blood-brain barrier transport of large molecules or to induce lysosomal enzyme transport across the blood-brain barrier ((±)epinephrine, insulin, retinoic acid, and lipopolysaccharide) in 2-week-old and adult mice. In 2-week-old adolescent mice, all these pharmacologic agents increased brain and heart uptake of phosphorylated human β-glucuronidase. In 8-week-old adult mice, manipulations with (±)epinephrine, insulin, and retinoic acid were significantly effective on uptake by brain and heart. The increased uptake of phosphorylated human β-glucuronidase was inhibited by mannose 6-phosphate for the agents (±)epinephrine and retinoic acid and by L-NG-nitroarginine methyl ester for the agent lipopolysaccharide in neonatal and adult mice. An in situ brain perfusion study revealed that retinoic acid directly modulated the transport of phosphorylated human β-glucuronidase across the blood-brain barrier. The present study indicates that there are multiple opportunities to at least transiently induce phosphorylated human β-glucuronidase transport at the adult blood-brain barrier.
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Affiliation(s)
- Akihiko Urayama
- Department of Neurology, University of Texas Medical School at Houston, Houston, TX, USA
| | - Jeffrey H Grubb
- Lysosomal Research, Ultragenyx Pharmaceutical Inc., Novato, CA, USA Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - William S Sly
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - William A Banks
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
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13
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Egleton RD, Abbruscato T. Drug abuse and the neurovascular unit. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 71:451-80. [PMID: 25307226 DOI: 10.1016/bs.apha.2014.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Drug abuse continues to create a major international epidemic affecting society. A great majority of past drug abuse research has focused mostly on the mechanisms of addiction and the specific effects of substance use disorders on brain circuits and pathways that modulate reward, motivation, craving, and decision making. Few studies have focused on the neurobiology of acute and chronic substance abuse as it relates to the neurovascular unit (brain endothelial cell, neuron, astrocyte, microglia, and pericyte). Increasing research indicates that all cellular components of the neurovascular unit play a pivotal role in both the process of addiction and how drug abuse affects the brain response to diseases. This review will focus on the specific effects of opioids, amphetamines, alcohol, and nicotine on the neurovascular unit and its role in addiction and adaption to brain diseases. Elucidation of the role of the neurovascular unit on the neurobiology associated with drug addiction will help to facilitate the development of better therapeutic approaches for drug-dependent individuals.
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Affiliation(s)
- Richard D Egleton
- Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
| | - Thomas Abbruscato
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas, USA.
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Østergaard L, Aamand R, Karabegovic S, Tietze A, Blicher JU, Mikkelsen IK, Iversen NK, Secher N, Engedal TS, Anzabi M, Jimenez EG, Cai C, Koch KU, Naess-Schmidt ET, Obel A, Juul N, Rasmussen M, Sørensen JCH. The role of the microcirculation in delayed cerebral ischemia and chronic degenerative changes after subarachnoid hemorrhage. J Cereb Blood Flow Metab 2013; 33:1825-37. [PMID: 24064495 PMCID: PMC3851911 DOI: 10.1038/jcbfm.2013.173] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 08/31/2013] [Accepted: 09/08/2013] [Indexed: 02/07/2023]
Abstract
The mortality after aneurysmal subarachnoid hemorrhage (SAH) is 50%, and most survivors suffer severe functional and cognitive deficits. Half of SAH patients deteriorate 5 to 14 days after the initial bleeding, so-called delayed cerebral ischemia (DCI). Although often attributed to vasospasms, DCI may develop in the absence of angiographic vasospasms, and therapeutic reversal of angiographic vasospasms fails to improve patient outcome. The etiology of chronic neurodegenerative changes after SAH remains poorly understood. Brain oxygenation depends on both cerebral blood flow (CBF) and its microscopic distribution, the so-called capillary transit time heterogeneity (CTH). In theory, increased CTH can therefore lead to tissue hypoxia in the absence of severe CBF reductions, whereas reductions in CBF, paradoxically, improve brain oxygenation if CTH is critically elevated. We review potential sources of elevated CTH after SAH. Pericyte constrictions in relation to the initial ischemic episode and subsequent oxidative stress, nitric oxide depletion during the pericapillary clearance of oxyhemoglobin, vasogenic edema, leukocytosis, and astrocytic endfeet swelling are identified as potential sources of elevated CTH, and hence of metabolic derangement, after SAH. Irreversible changes in capillary morphology and function are predicted to contribute to long-term relative tissue hypoxia, inflammation, and neurodegeneration. We discuss diagnostic and therapeutic implications of these predictions.
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Affiliation(s)
- Leif Østergaard
- 1] Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark [2] Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark
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15
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Urayama A. Toward the successful delivery of lysosomal enzymes across the blood-brain barrier. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Akihiko Urayama
- Department of Neurology; University of Texas Medical School at Houston; Houston; TX; USA
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16
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Hakkarainen JJ, Rilla K, Suhonen M, Ruponen M, Forsberg MM. Re-evaluation of the role of P-glycoprotein inin vitrodrug permeability studies with the bovine brain microvessel endothelial cells. Xenobiotica 2013; 44:283-94. [DOI: 10.3109/00498254.2013.823529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Chancellor MB, Staskin DR, Kay GG, Sandage BW, Oefelein MG, Tsao JW. Blood–Brain Barrier Permeation and Efflux Exclusion of Anticholinergics Used in the Treatment of Overactive Bladder. Drugs Aging 2012; 29:259-73. [DOI: 10.2165/11597530-000000000-00000] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Spindler V, Waschke J. Beta-adrenergic stimulation contributes to maintenance of endothelial barrier functions under baseline conditions. Microcirculation 2011; 18:118-27. [PMID: 21166930 DOI: 10.1111/j.1549-8719.2010.00072.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVES cAMP signaling within the endothelium is known to reduce paracellular permeability and to protect against loss of barrier functions under various pathological conditions. Because activation of β-adrenergic receptors elevates cellular cAMP, we tested whether β-adrenergic receptor signaling contributes to the maintenance of baseline endothelial barrier properties. METHODS We compared hydraulic conductivity of rat postcapillary venules in vivo with resistance measurements and with reorganization of endothelial adherens junctions in cultured microvascular endothelial cells downstream of β-adrenergic receptor-mediated changes of cAMP levels. RESULTS Inhibition of β-adrenergic receptors by propranolol increased hydraulic conductivity, reduced both cAMP levels and TER of microvascular endothelial cell monolayers and induced fragmentation of VE-cadherin staining. In contrast, activation by epinephrine both increased cAMP levels and TER and resulted in linearized VE-cadherin distribution, however this was not sufficient to block barrier-destabilization by propranolol. Similarly, PDE inhibition did not prevent propranolol-induced TER reduction and VE-cadherin reorganization whereas increased cAMP formation by AC activation enhanced endothelial barrier functions under baseline conditions and under conditions of propranolol treatment. CONCLUSIONS Our results indicate that generation of cAMP mediated by activation of β-adrenergic receptor signaling contributes to the maintenance of endothelial barrier properties under baseline conditions.
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Affiliation(s)
- Volker Spindler
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, Würzburg, Germany
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Spindler V, Vielmuth F, Schmidt E, Rubenstein DS, Waschke J. Protective endogenous cyclic adenosine 5'-monophosphate signaling triggered by pemphigus autoantibodies. THE JOURNAL OF IMMUNOLOGY 2010; 185:6831-8. [PMID: 21037102 DOI: 10.4049/jimmunol.1002675] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Pemphigus vulgaris (PV) is an autoimmune skin disease mediated by autoantibodies directed against the cadherin-type cell adhesion molecules desmoglein (Dsg) 3 and Dsg1 and is characterized by loss of keratinocyte cohesion and epidermal blistering. Several intracellular signaling pathways, such as p38MAPK activation and RhoA inhibition, have been demonstrated to be altered following autoantibody binding and to be causally involved in loss of keratinocyte cohesion. In this paper, we demonstrate that cAMP-mediated signaling completely prevented blister formation in a neonatal pemphigus mouse model. Furthermore, elevation of cellular cAMP levels by forskolin/rolipram or β receptor agonist isoproterenol blocked loss of intercellular adhesion, depletion of cellular Dsg3, and morphologic changes induced by Ab fractions of PV patients (PV-IgG) in cultured keratinocytes. Incubation with PV-IgG alone increased cAMP levels, indicating that cAMP elevation may be a cellular response pathway to strengthen intercellular adhesion. Our data furthermore demonstrate that this protective pathway may involve protein kinase A signaling because protein kinase A inhibition attenuated recovery from PV-IgG-induced cell dissociation. Finally, cAMP increase interfered with PV-IgG-induced signaling by preventing p38MAPK activation both in vitro and in vivo. Taken together, our data provide insights into the cellular response mechanisms following pemphigus autoantibody binding and point to a possible novel and more specific therapeutic approach in pemphigus.
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Affiliation(s)
- Volker Spindler
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
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Poly(ε-caprolactone)-block-poly(ethyl ethylene phosphate) micelles for brain-targeting drug delivery: in vitro and in vivo valuation. Pharm Res 2010; 27:2657-69. [PMID: 20848303 DOI: 10.1007/s11095-010-0265-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Accepted: 08/30/2010] [Indexed: 12/15/2022]
Abstract
PURPOSE The purpose of this work was to investigate the potential of poly(ε-caprolactone)-block-poly(ethyl ethylene phosphate) (PCL-PEEP) micelles for brain-targeting drug delivery. METHOD The coumarin-6-loaded PCL-PEEP micelles (CMs) were prepared and characterized. The cellular uptake of CMs was evaluated on in vitro model of brain-blood barrier (BBB), and the brain biodistribution of CMs in ICR mice was investigated. RESULTS PCL-PEEP could self-assemble into 20 nm micelles in water with the critical micelle concentration (CMC) 0.51 μg/ml and high coumarin-6 encapsulation efficiency (92.5 ± 0.7%), and the micelles were stable in 10% FBS with less than 25% leakage of incorporated coumarin-6 during 24 h incubation at 37°C. The cellular uptake of CMs by BBB model was significantly higher and more efficient than coumarin-6 solution (CS) at 50 ng/ml. Compared with CS, 2.6-fold of coumarin-6 was found in the brains of CM-treated mice, and C(max) of CMs was 4.74% of injected dose/g brain. The qualitative investigation on the brain distribution of CMs indicated that CMs were prone to accumulate in hippocampus and striatum. CONCLUSION These results suggest that PCL-PEEP micelles could be a promising brain-targeting drug delivery system with low toxicity.
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Urayama A, Grubb JH, Banks WA, Sly WS. Epinephrine enhances lysosomal enzyme delivery across the blood brain barrier by up-regulation of the mannose 6-phosphate receptor. Proc Natl Acad Sci U S A 2007; 104:12873-8. [PMID: 17646643 PMCID: PMC1937559 DOI: 10.1073/pnas.0705611104] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Delivering therapeutic levels of lysosomal enzymes across the blood-brain barrier (BBB) has been a pivotal issue in treating CNS storage diseases, including the mucopolysaccharidoses. An inherited deficiency of beta-glucuronidase (GUS) causes mucopolysaccharidosis type VII that is characterized by increased systemic and CNS storage of glycosaminoglycans. We previously showed that the neonate uses the mannose 6-phosphate (M6P) receptor to transport phosphorylated GUS (P-GUS) across the BBB and that this transporter is lost with maturation. Induction of expression of this BBB transporter would make enzyme replacement therapy in the adult possible. Here, we tested pharmacological manipulation with epinephrine to restore functional transport of P-GUS across the adult BBB. Epinephrine (40 nmol) coinjected i.v. with (131)I-P-GUS induced the transport across the BBB in 8-week-old mice. The brain influx rate of (131)I-P-GUS (0.29 mul/g per min) returned to the level seen in neonates. Capillary depletion showed that 49% of the (131)I-P-GUS in brain was in brain parenchyma. No increases of influx rate or the vascular space for (125)I-albumin, a vascular marker, was observed with epinephrine (40 nmol), showing that enhanced passage was not caused by disruption of the BBB. Brain uptake of (131)I-P-GUS was significantly inhibited by M6P in a dose-dependent manner, whereas epinephrine failed to increase brain uptake of nonphosphorylated GUS. Thus, the effect of epinephrine on the transport of (131)I-P-GUS was ligand specific. These results indicate that epinephrine restores the M6P receptor-mediated functional transport of (131)I-P-GUS across the BBB in adults to levels seen in the neonate.
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Affiliation(s)
- Akihiko Urayama
- *Geriatric Research Education and Clinical Center, Veterans Affairs Medical Center, St. Louis, MO 63106; and
- Department of Internal Medicine, Division of Geriatric Medicine, and
| | - Jeffrey H. Grubb
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
| | - William A. Banks
- *Geriatric Research Education and Clinical Center, Veterans Affairs Medical Center, St. Louis, MO 63106; and
- Department of Internal Medicine, Division of Geriatric Medicine, and
- To whom correspondence may be addressed. E-mail: or
| | - William S. Sly
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
- To whom correspondence may be addressed. E-mail: or
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Borges N, Sarmento A, Azevedo I. Comment on "Beta-blocker exposure is associated with improved survival after severe traumatic brain injury". THE JOURNAL OF TRAUMA 2007; 62:1537-8; author reply 1538-9. [PMID: 17563684 DOI: 10.1097/ta.0b013e31805174a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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Tanaka N, Nejime N, Kagota S, Kubota Y, Yudo K, Nakamura K, Kunitomo M, Takahashi K, Hashimoto M, Shinozuka K. ATP participates in the regulation of microvessel permeability. J Pharm Pharmacol 2006; 58:481-7. [PMID: 16597365 DOI: 10.1211/jpp.58.4.0007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
We demonstrated previously that stimulation of the P2Y receptor enhanced the macromolecular permeability of cultured endothelial cell monolayers via the paracellular pathway. To determine whether the P2Y receptor participates in the regulation of permeability in intact microvessels, we have examined the effects of exogenous and endogenous ATP on the permeation of the surface tissue of perfused rat tail caudal artery using a fluorescein isothiocyanate-dextran (FD-4; MW 4400; 1.0 mg mL(-1)). The permeation of FD-4 was assessed by a confocal fluorescence imaging system. We found that 2-methylthioadenosine 5'-triphosphate, a P2Y receptor agonist, enhanced the fluorescence intensity of FD-4 in the surface of the rat caudal artery tissue and that it was inhibited by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid, a P2 receptor antagonist. Also, noradrenaline, a sympathetic neurotransmitter, and bradykinin, an inflammatory autacoid, enhanced the fluorescence intensity of FD-4 in the surface tissue of the rat caudal artery. The enhancement by noradrenaline was significantly inhibited by the P2 receptor antagonist. In addition, noradrenaline and bradykinin caused the release of ATP, ADP, AMP and adenosine from the endothelium of the rat caudal artery. These results indicated that the exogenous and endogenous ATP increased the macromolecular permeability of blood capillaries via the P2Y receptor. Such purinergic regulation of endothelial permeability may function in physiological and pathophysiological conditions.
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Affiliation(s)
- Naoko Tanaka
- First Department of Pharmacology, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, Nobeoka, Miyazaki 882-8508, Japan
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Nicolazzo JA, Charman SA, Charman WN. Methods to assess drug permeability across the blood-brain barrier. J Pharm Pharmacol 2006; 58:281-93. [PMID: 16536894 DOI: 10.1211/jpp.58.3.0001] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Much research has focussed on the development of novel therapeutic agents to target various central nervous system disorders, however less attention has been given to determining the potential of such agents to permeate the blood-brain barrier (BBB), a factor that will ultimately govern the effectiveness of these agents in man. In order to assess the potential for novel compounds to permeate the BBB, various in-vitro, in-vivo and in-silico methods may be employed. Although in-vitro models (such as primary cell culture and immortalized cell lines) are useful as a screening method and can appropriately rank compounds in order of BBB permeability, they often correlate poorly to in-vivo brain uptake due to down-regulation of some BBB-specific transporters. In-vivo models (such as the internal carotid artery single injection or perfusion, intravenous bolus injection, brain efflux index and intracerebral microdialysis) provide more accurate information regarding brain uptake, and these can be complemented with novel imaging techniques (such as magnetic resonance imaging and positron emission tomography), although such methods are not suited to high-throughput permeability assessment. This paper reviews current methods used for assessing BBB permeability and highlights the particular advantages and disadvantages associated with each method, with a particular focus on methods suitable for moderate- to high-throughput screening.
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Affiliation(s)
- Joseph A Nicolazzo
- Centre for Drug Candidate Optimisation, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
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Neuhaus W, Bogner E, Wirth M, Trzeciak J, Lachmann B, Gabor F, Noe CR. A novel tool to characterize paracellular transport: the APTS-dextran ladder. Pharm Res 2006; 23:1491-501. [PMID: 16779707 DOI: 10.1007/s11095-006-0256-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2006] [Accepted: 02/17/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE The aim of this work was to develop an easy, manageable, and precise analytic tool to describe the tightness of cell layers by a molecular weight ladder. METHODS Dextrans were labeled by reductive amination with fluorescent 8-aminopyrene-1,3,6-trisulfonate (APTS). This mixture, including the internal standard diazepam, was used for transport studies in Transwell models using Caco-2, ECV304, and PBMEC/C1-2 cell lines. Samples were analyzed by fluorimetry, capillary electrophoresis, and reverse-phase high-performance liquid chromatography. RESULTS Following this approach, a logarithm correlation of R2 = 0.8958 between transepithelial electrical resistance (TEER) and APTS-dextran permeability was shown. In addition, a TEER-dependent permeability pattern could be observed including each single fraction from free APTS, APTS-glucose up to APTS-dextran consisting of 35 glucose units. The TEER-independent permeability coefficients of diazepam and confocal laser scanning microscopy images confirmed the paracellular transport of APTS-dextran. CONCLUSIONS All in all, the developed APTS-dextran ladder is a useful tool to characterize cell layer tightness and especially to describe paracellular transport ways and the extent of leakiness of cell layers (for blood-brain barrier or intestinal studies) over time--applying a wide array from smaller to larger molecules at the same time to refine TEER, sucrose, or Evans blue measurements.
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Affiliation(s)
- Winfried Neuhaus
- Department of Medicinal Chemistry, University of Vienna, Pharmacy Center, Althanstrasse 14, A-1090, Vienna, Austria
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Deli MA, Abrahám CS, Kataoka Y, Niwa M. Permeability studies on in vitro blood-brain barrier models: physiology, pathology, and pharmacology. Cell Mol Neurobiol 2005; 25:59-127. [PMID: 15962509 DOI: 10.1007/s10571-004-1377-8] [Citation(s) in RCA: 472] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
(1) The specifically regulated restrictive permeability barrier to cells and molecules is the most important feature of the blood-brain barrier (BBB). The aim of this review was to summarize permeability data obtained on in vitro BBB models by measurement of transendothelial electrical resistance and by calculation of permeability coefficients for paracellular or transendothelial tracers. (2) Results from primary cultures of cerebral microvascular endothelial cells or immortalized cell lines from bovine, human, porcine, and rodent origin are presented. Effects of coculture with astroglia, neurons, mesenchymal cells, blood cells, and conditioned media, as well as physiological influence of serum components, hormones, growth factors, lipids, and lipoproteins on the barrier function are discussed. (3) BBB permeability results gained on in vitro models of pathological conditions including hypoxia and reoxygenation, neurodegenerative diseases, or bacterial and viral infections have been reviewed. Effects of cytokines, vasoactive mediators, and other pathogenic factors on barrier integrity are also detailed. (4) Pharmacological treatments modulating intracellular cyclic nucleotide or calcium levels, and activity of protein kinases, protein tyrosine phosphatases, phospholipases, cyclooxygenases, or lipoxygenases able to change BBB integrity are outlined. Barrier regulation by drugs involved in the metabolism of nitric oxide and reactive oxygen species, as well as influence of miscellaneous treatments are also listed and evaluated. (5) Though recent advances resulted in development of improved in vitro BBB model systems to investigate disease modeling, drug screening, and testing vectors targeting the brain, there is a need for checking validity of permeability models and cautious interpretation of data.
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Affiliation(s)
- Máiria A Deli
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári körút 62, H-6726 Szeged, Hungary.
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Abstract
Well-documented central nervous system changes during colitis suggest possible alterations of blood-brain barrier (BBB) permeability, yet the integrity of the BBB has not been fully evaluated in experimental colitis. Our aim was to investigate whether trinitrobenzene sulphonic acid (TNBS) colitis was associated with an increase in the permeability of the BBB. Sprague-Dawley rats were given an intracolonic injection of saline or TNBS and studied 1, 2, 3, 7 and 21 days after treatment. The extravasation of endogenous immunoglobulin G, a large molecule, was not altered at any time after TNBS treatment. In contrast, significant increases in the BBB leakage of sodium fluorescein, a much smaller molecule, were observed 1 and 2 days after the induction of colitis, in and around the circumventricular organs; the organum vasculosum of the lamina terminalis, subfornical organ and median eminence of the hypothalamus. TNBS-treated rats also exhibited sodium fluorescein leakage in focal areas in the brain parenchyma. The expression of endothelial barrier antigen, a protein associated with the BBB, was reduced about 60% 48 h after the induction of colitis. This returned to control values by 3 weeks, when colitis had largely subsided. In conclusion, experimental colitis transiently increased permeability of the brain to small molecules through a mild disruption of the BBB.
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Affiliation(s)
- S S Natah
- Institute for Infection, Immunity and Inflammation, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada
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Kuang F, Wang BR, Zhang P, Fei LL, Jia Y, Duan XL, Wang X, Xu Z, Li GL, Jiao XY, Ju G. Extravasation of blood-borne immunoglobulin G through blood-brain barrier during adrenaline-induced transient hypertension in the rat. Int J Neurosci 2004; 114:575-91. [PMID: 15204054 DOI: 10.1080/00207450490422731] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The effect of transient hypertension on blood-brain barrier (BBB) permeability, particularly on extravasation of immunoglobulin G (IgG), has not been fully understood. In the present experiment, we investigated the time course of endogenous albumin and IgG extravasation through BBB and the localization of extravasated IgG in brain parenchyma during adrenaline(AD)-induced transient hypertension in the rat by using Evans blue fluorescence, immunohistochemistry, and Western blot. The results showed that a bolus injection of AD (10 microg/kg) induced a transient elevation of arterial pressure lasting about 1 min. The endogenous albumin and IgG entered the brain parenchyma via BBB only when hypertension occurred. Electron microscopically, the IgG-like immunoreactivities were predominantly seen in the cytoplasm of endothelia of capillaries, pericytes, extracellular space of parenchyma, and the cytoplasm of glial cells. The results suggest that circulating IgG or antibodies might contact the structures of brain parenchyma through passage of BBB when its permeability is temporally changed by transient hypertension. This phenomenon implies a possible mechanism of pathogenesis for immune-mediated diseases in the brain.
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Affiliation(s)
- Fang Kuang
- Institute of Neurosciences, Fourth Military Medical University, Xi'an, Shaanxi, People's Republic of China
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Van Landeghem FKH, Schreiber S, Unterberg AW, Von Deimling A, Stover JF. Differential Concentration-Dependent Effects of Prolonged Norepinephrine Infusion on Intraparenchymal Hemorrhage and Cortical Contusion in Brain-Injured Rats. J Neurotrauma 2003; 20:1327-37. [PMID: 14748981 DOI: 10.1089/089771503322686120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Under clinical conditions catecholamines are infused to elevate cerebral perfusion pressure and improve impaired posttraumatic cerebral microcirculation. This, however, is associated with the risk of additional hemorrhage in the acute phase following traumatic brain injury. In the present study we investigated the dose-dependent effects of prolonged norepinephrine infusion on arterial blood pressure, blood glucose, and structural damage in brain-injured rats. At 4 h following induction of a focal cortical contusion (CCI), 40 rats were randomized to receive low (0.15), medium (0.3), or high dose (1 microg/kg/min) norepinephrine. Control rats were given equal volume of NaCl. Norepinephrine and NaCl were infused intravenously via Alzet osmotic pumps for 44 h. Mean arterial blood pressure (MABP), blood gases and blood glucose were determined before, at 4, 24, 48 h after CCI in repeatedly anesthetized rats (n = 28). Systolic arterial blood pressure (SABP) was measured using the tail cuff method in awake, restrained rats (n = 12). Cortical contusion and intraparenchymal hemorrhage volume were quantified at 48 h in all rats. MABP determined in anesthetized rats was only marginally increased. SABP was significantly elevated during infusion of medium and high dose norepinephrine in awake rats, exceeding 140 mm Hg. Medium and high dose norepinephrine significantly increased cortical hemorrhage by 157% and 142%, without increasing the cortical contusion volume. Low dose norepinephrine significantly reduced the cortical contusion by 44%. Norepinephrine aggravates the underlying brain damage during the acute posttraumatic phase. Future studies are needed to determine the least deleterious norepinephrine concentration.
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Affiliation(s)
- Frank K H Van Landeghem
- Institute of Neuropathology, Charité Campus Virchow Klinikum, Humboldt-University, 13353 Berlin, Germany.
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Gumbleton M, Audus KL. Progress and limitations in the use of in vitro cell cultures to serve as a permeability screen for the blood-brain barrier. J Pharm Sci 2001; 90:1681-98. [PMID: 11745727 DOI: 10.1002/jps.1119] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A relatively simple, widely applicable, and robust in vitro method of predicting blood-brain barrier (BBB) permeability to central nervous system-acting drugs is an increasing need. A cell-based model offers the potential to account for transcellular and paracellular drug diffusional processes, metabolism, and active transport processes, as well as nondefined interactions between a drug and cellular material that may impact upon a membrane's overall permeability profile. Any in vitro BBB cell model to be utilized for the transendothelial BBB permeability screening of potential central nervous system drugs must display reproducible solute permeability, and a number of other general criteria including: a restrictive paracellular barrier; a physiologically realistic cell architecture; the functional expression of key transporter mechanisms; and allow ease of culture to meet the technical and time constraints of a screening program. This article reviews the range of in vitro cell-based BBB models available, including the primary/low passage bovine and porcine brain endothelial cultures as well as the spectrum of immortalized brain endothelial cell lines that have been established. The article further discusses the benefits and limitations of exploiting such systems as in vitro BBB permeability screens.
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Affiliation(s)
- M Gumbleton
- Pharmaceutical Cell Biology, Welsh School of Pharmacy, Redwood Building, Cardiff University, Cardiff, CF10 3XF, United Kingdom.
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Ohara Y, McCarron RM, Hoffman TT, Sugano H, Bembry J, Lenz FA, Spatz M. Adrenergic mediation of TNF alpha-stimulated ICAM-1 expression on human brain microvascular endothelial cells. ACTA NEUROCHIRURGICA. SUPPLEMENT 2001; 76:117-20. [PMID: 11449988 DOI: 10.1007/978-3-7091-6346-7_24] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Adrenergic innervation derived from locus ceruleus has been implicated in regulating BBB permeability and inflammatory responses associated with neurological disorders. This report demonstrates that adrenergic agents attenuate the tumor necrosis factor-alpha (TNF alpha)-induced expression of intercellular adhesion molecule-1 (ICAM-1) on cerebral microvascular endothelial cells (HBMEC) derived from human brains. HBMEC were incubated with isoproterenol (1-10 microM) alone or in the presence of propranolol (10 microM) for 30 min followed by the addition of various concentrations of TNF alpha. ICAM-1 expression on cultured HBMEC was dose-dependently upregulated by TNF alpha. Incubation with isoproterenol significantly reduced levels of ICAM-1 expression indicating the possible involvement of adrenergic agents on ICAM-1 expression. Treatment with propranolol (beta 1/beta 2-adrenergic antagonist) and butoxamine (beta 2-adrenergic antagonist), but not atenolol (beta 1-adrenergic antagonist) reversed this inhibitory effect. Isoproterenol also dose-dependently stimulated cAMP production (assayed by RIA) by HBMEC; propranolol treatment abolished this effect. These data show that the beta 2-adrenergic receptor/cAMP pathway may be partly involved in TNF alpha-stimulated ICAM-1 expression and indicate the possible involvement of adrenergic mediation of capillary function including BBB integrity.
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Affiliation(s)
- Y Ohara
- Resuscitative Medicine Department, Naval Medical Research Center, Silver Spring, MD, USA
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Gaillard PJ, de Boer AG. Relationship between permeability status of the blood-brain barrier and in vitro permeability coefficient of a drug. Eur J Pharm Sci 2000; 12:95-102. [PMID: 11102736 DOI: 10.1016/s0928-0987(00)00152-4] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The aim was to test the hypothesis that the assessment of basal and drug-induced changes in permeability of the blood-brain barrier (BBB) during in vitro drug transport assays is essential for an accurate estimation of the permeability coefficient of a drug. METHODS An in vitro BBB model was used, comprising of brain capillary endothelial cells (BCEC) and astrocytes co-cultured on semi-permeable filter inserts. Experiments were performed under control and challenged experimental circumstances, induced to simulate drug effects. The apparent BBB permeability coefficient for two markers for paracellular drug transport, sodium fluorescein (P(app,FLU), M(w) 376 Da) and FITC-labeled dextran (P(app,FD4), M(w) 4 kDa), was determined. Transendothelial electrical resistance (TEER) was used to quantify basal and (simulated) drug-induced changes in permeability of the in vitro BBB. The relationship between P(app) and TEER was determined. Drug effects were simulated by exposure to physiologically active endogenous and exogenous substances (i.e., histamine, deferroxamine mesylate, adrenaline, noradrenaline, bradykinin, vinblastine, sodium nitroprusside and lipopolysaccharide). RESULTS P(app,FLU) and P(app,FD4) in control experiments varied from 1.6 up to 17.6 (10(-6)cm/s) and 0.3 up to 7. 3 (10(-6)cm/s), respectively; while for individual filters P(app, FLU) was 4 times higher than P(app,FD4) (R(2)=0.97). As long as TEER remained above 131.Omega cm(2) for FLU or 122.Omega cm(2) for FD4 during the transport assay, P(app) remained independent from the basal permeability of the in vitro BBB. Below these TEER values, P(app) increased exponentially. This nonlinear relationship between basal BBB permeability and P(app) was described by a one-phase exponential decay model. From this model the BBB permeability status independent permeability coefficients for FLU and FD4 (P(FLU) and P(FD4)) were estimated to be 2.2+/-0.1 and 0.48+/-0.03 (10(-6)cm/s), respectively. In the experimentally challenged experiments, a reliable indication for P(FLU) and P(FD4) could be estimated only after the (simulated) drug-induced change in BBB permeability was taken into account. CONCLUSIONS The assessment of basal BBB permeability status during drug transport assays was essential for an accurate estimation of the in vitro permeability coefficient of a drug. To accurately extrapolate the in vitro permeability coefficient of a drug to the in vivo situation, it is essential that drug-induced changes in the in vitro BBB permeability during the drug transport assay are determined.
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Affiliation(s)
- P J Gaillard
- Department of Pharmacology, Leiden/Amsterdam Center for Drug Research (LACDR), Leiden University, P.O. Box 9503, 2300 RA, Leiden, The Netherlands
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Stagni G, O'Donnell D, Liu YJ, Kellogg DL, Shepherd AM. Iontophoretic current and intradermal microdialysis recovery in humans. J Pharmacol Toxicol Methods 1999; 41:49-54. [PMID: 10507758 DOI: 10.1016/s1056-8719(99)00027-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
When microdialysis (MD) is used to study dermal delivery by iontophoresis, the effects of current may alter MD recovery through an increase in temperature, a change of pH, hyperemia, and dermal hydration. The objective of this work is to assess whether these effects of current may cause a measurable change in the retrodialysis of a model compound (sodium fluorescein, Fl). Two linear MD-probes were inserted in the forearm dermis of healthy human volunteers and perfused with Ringer's solution containing Fl. Two identical iontophoresis chambers (IC, filled with NaCl in propylene glycol) were placed over the MD-probes. Each IC included a laser Doppler flowmetry probe to monitor skin blood flow. At one IC, current was applied for two periods of 30 min each, separated by 30 min of no current. No current was applied to the control site. Dialysate samples were collected every 5 min and analyzed for Fl by HPLC. Skin blood flow increased in response to iontophoresis, on average, 570% compared to the control site. However, there was no difference in the recovery of Fl between the current-active site versus the control site, and between the period with applied current versus the period with no current. In conclusion, iontophoretic current did not affect intradermal MD recovery.
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Affiliation(s)
- G Stagni
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, 78284-6205, USA.
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Mori K, Kato H, Stevens J, Kito K. Effects of epidural epinephrine on the spinal cord accumulation of epidural clonidine in rabbits. Anesth Analg 1998; 86:1145-6. [PMID: 9585315 DOI: 10.1097/00000539-199805000-00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Mori K, Kato H, Stevens J, Kito K. Effects of Epidural Epinephrine on the Spinal Cord Accumulation of Epidural Clonidine in Rabbits. Anesth Analg 1998. [DOI: 10.1213/00000539-199805000-00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Epinephrine Increases Spinal Cord Concentrations of [(3) H]-Clonidine Hydrochloride in Rabbits After Epidural Infusion. Anesth Analg 1997. [DOI: 10.1213/00000539-199708000-00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Fu ES, Naidu KA, Prockop LD. Epinephrine increases spinal cord concentrations of [3H]-clonidine hydrochloride in rabbits after epidural infusion. Anesth Analg 1997; 85:324-7. [PMID: 9249108 DOI: 10.1097/00000539-199708000-00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Epinephrine is often given with epidurally administered drugs to prolong and enhance analgesia, which is partly attributed to alpha-adrenergic processes. This investigation evaluates the effect of epinephrine on the distribution of epidurally administered [3H]-clonidine hydrochloride (clonidine HCl) in serum and in the central nervous system. After placing a lumbar epidural catheter via a laminectomy, rabbits were randomly assigned to receive 20 microCi of clonidine HCl with epinephrine (1:200,000) (n = 5) or without (control; n = 5) for 90 min. During the administration, which included bolus and slow infusion, blood samples were collected at 15-min intervals. At the end of the administration, rabbits were perfused with normal saline, leading to exsanguination. Brain and spinal cord tissues were excised for radiometric analysis. In both groups, the concentration of clonidine HCl was greatest in the lumbar cord. Epinephrine further enhanced accumulation of clonidine HCl into the lumbar cord but did not alter the concentration of clonidine HCl in serum, brain, cervical cord, and thoracic cord. We conclude that lumbar administration of epidural clonidine HCl leads to increased concentrations in the lumbar cord, which is further enhanced by epinephrine. The increased spinal cord accumulation of clonidine may be another mechanism by which epinephrine improves epidural analgesia.
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Affiliation(s)
- E S Fu
- Department of Anesthesiology, University of South Florida College of Medicine, Tampa 33612-4799, USA.
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Cohen Z, Molinatti G, Hamel E. Astroglial and vascular interactions of noradrenaline terminals in the rat cerebral cortex. J Cereb Blood Flow Metab 1997; 17:894-904. [PMID: 9290587 DOI: 10.1097/00004647-199708000-00008] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Noradrenaline (NA) has been shown to influence astrocytic and vascular functions related to brain homeostasis, metabolism, local blood flow, and blood-brain barrier permeability. In the current study, we investigate the possible associations that exist between NA-immunoreactive nerve terminals and astrocytes and intraparenchymal blood vessels in the rat frontoparietal cortex, both at the light and electron microscopic levels. As a second step, we sought to determine whether the NA innervation around intracortical microvessels arises from peripheral or central structures by means of injections of N-(2-chloroethyl-N-ethyl-2-bromobenzylamine) (DSP-4), a neurotoxin that specifically destroys NA neurons from the locus ceruleus. At the light microscopic level, 6.8% of all NA-immunoreactive nerve terminals in the frontoparietal cortex were associated with vascular walls, and this perivascular noradrenergic input, together with that of the cerebral cortex, almost completely disappeared after DSP-4 administration. When analyzed at the ultrastructural level in control rats, NA terminals in the neuropil had a mean surface area of 0.53 +/- 0.03 micron2 and were rarely junctional (synaptic incidence close to 7%). Perivascular terminals (located within a 3-micron perimeter from the vessel basal lamina) counted at the electron microscopic level represented 8.8% of the total NA terminals in the cortical tissue. They were smaller (0.29 +/- 0.01 micron2, P < 0.05) than their neuronal counterparts and were located, on average, 1.34 +/- 0.08 microns away from intracortical blood vessels, which consisted mostly of capillaries (65%). None of the perivascular NA terminals engaged in junctional contacts with surrounding neuronal or vascular elements. The primary targets of both neuronal and perivascular NA nerve terminals consisted of dendrites, nerve terminals, astrocytes, and axons, whereas in the immediate vicinity (0.25 micron or less) of the microvessels, astrocytic processes represented the major target. The results of the current study show that penetrating arteries and intracortical microvessels receive a central NA input, albeit parasynaptic in its interaction, originating from the locus ceruleus. Particularly, they point to frequent appositions between both neuronal and perivascular NA terminals and astroglial cells and their processes. Such NA neuronal-glial and neuronal-glial-vascular associations could be of significance in the regulation of local metabolic and vascular functions under normal and pathologic situations.
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Affiliation(s)
- Z Cohen
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Québec, Canada
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Audus KL, Ng L, Wang W, Borchardt RT. Brain microvessel endothelial cell culture systems. PHARMACEUTICAL BIOTECHNOLOGY 1996; 8:239-58. [PMID: 8791813 DOI: 10.1007/978-1-4899-1863-5_13] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- K L Audus
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66045, USA
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