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Papasilekas T, Themistoklis KM, Melanis K, Patrikelis P, Spartalis E, Korfias S, Sakas D. A Brief Review of Brain's Blood Flow-Metabolism Coupling and Pressure Autoregulation. J Neurol Surg A Cent Eur Neurosurg 2021; 82:257-261. [PMID: 33583012 DOI: 10.1055/s-0040-1721682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND The human brain, depending on aerobic glycolysis to cover its metabolic needs and having no energy reserves whatsoever, relies on a constant and closely regulated blood supply to maintain its structural and functional integrity. Cerebral autoregulation, that is, the brain's intrinsic ability to regulate its own blood flow independently from the systemic blood pressure and cardiac output, is an important physiological mechanism that offers protection from hypoperfusion injury. DISCUSSION Two major independent mechanisms are known to be involved in cerebral autoregulation: (1) flow-metabolism coupling and (2) myogenic responses of cerebral blood vessels to changes in transmural/arterial pressure. A third, less prominent component of cerebral autoregulation comes in the form of neurogenic influences on cerebral vasculature. CONCLUSION Although fragmentation of cerebral autoregulation in separate and distinct from each other mechanisms is somewhat arbitrary, such a scheme is useful for reasons of simplification and to better understand their overall effect. Comprehension of cerebral autoregulation is imperative for clinicians in order for them to mitigate consequences of its impairment in the context of traumatic brain injury, subarachnoid hemorrhage, stroke, or other pathological conditions.
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Affiliation(s)
| | | | - Konstantinos Melanis
- Department of Neurology, Evangelismos Athens General Hospital, Athens, Attica, Greece
| | - Panayiotis Patrikelis
- Department of Neurosurgery, Evangelismos Athens General Hospital, Athens, Attica, Greece
| | - Eleftherios Spartalis
- Laboratory of Experimental Surgery and Surgical Research, University of Athens, Athinon, Greece
| | - Stefanos Korfias
- Department of Neurosurgery, Evangelismos Athens General Hospital, Athens, Attica, Greece
| | - Damianos Sakas
- Department of Neurosurgery, Evangelismos Athens General Hospital, Athens, Attica, Greece
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Špiranec K, Chen W, Werner F, Nikolaev VO, Naruke T, Koch F, Werner A, Eder-Negrin P, Diéguez-Hurtado R, Adams RH, Baba HA, Schmidt H, Schuh K, Skryabin BV, Movahedi K, Schweda F, Kuhn M. Endothelial C-Type Natriuretic Peptide Acts on Pericytes to Regulate Microcirculatory Flow and Blood Pressure. Circulation 2019; 138:494-508. [PMID: 29626067 DOI: 10.1161/circulationaha.117.033383] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Peripheral vascular resistance has a major impact on arterial blood pressure levels. Endothelial C-type natriuretic peptide (CNP) participates in the local regulation of vascular tone, but the target cells remain controversial. The cGMP-producing guanylyl cyclase-B (GC-B) receptor for CNP is expressed in vascular smooth muscle cells (SMCs). However, whereas endothelial cell-specific CNP knockout mice are hypertensive, mice with deletion of GC-B in vascular SMCs have unaltered blood pressure. METHODS We analyzed whether the vasodilating response to CNP changes along the vascular tree, ie, whether the GC-B receptor is expressed in microvascular types of cells. Mice with a floxed GC-B ( Npr2) gene were interbred with Tie2-Cre or PDGF-Rβ-Cre ERT2 lines to develop mice lacking GC-B in endothelial cells or in precapillary arteriolar SMCs and capillary pericytes. Intravital microscopy, invasive and noninvasive hemodynamics, fluorescence energy transfer studies of pericyte cAMP levels in situ, and renal physiology were combined to dissect whether and how CNP/GC-B/cGMP signaling modulates microcirculatory tone and blood pressure. RESULTS Intravital microscopy studies revealed that the vasodilatatory effect of CNP increases toward small-diameter arterioles and capillaries. CNP consistently did not prevent endothelin-1-induced acute constrictions of proximal arterioles, but fully reversed endothelin effects in precapillary arterioles and capillaries. Here, the GC-B receptor is expressed both in endothelial and mural cells, ie, in pericytes. It is notable that the vasodilatatory effects of CNP were preserved in mice with endothelial GC-B deletion, but abolished in mice lacking GC-B in microcirculatory SMCs and pericytes. CNP, via GC-B/cGMP signaling, modulates 2 signaling cascades in pericytes: it activates cGMP-dependent protein kinase I to phosphorylate downstream targets such as the cytoskeleton-associated vasodilator-activated phosphoprotein, and it inhibits phosphodiesterase 3A, thereby enhancing pericyte cAMP levels. These pathways ultimately prevent endothelin-induced increases of pericyte calcium levels and pericyte contraction. Mice with deletion of GC-B in microcirculatory SMCs and pericytes have elevated peripheral resistance and chronic arterial hypertension without a change in renal function. CONCLUSIONS Our studies indicate that endothelial CNP regulates distal arteriolar and capillary blood flow. CNP-induced GC-B/cGMP signaling in microvascular SMCs and pericytes is essential for the maintenance of normal microvascular resistance and blood pressure.
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Affiliation(s)
- Katarina Špiranec
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Wen Chen
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Franziska Werner
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (V.O.N.)
| | - Takashi Naruke
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Franziska Koch
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Andrea Werner
- Institute of Physiology, University of Regensburg, Germany (A.W., F.S.)
| | - Petra Eder-Negrin
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Rodrigo Diéguez-Hurtado
- Max-Planck-Institute for Molecular Biomedicine, Department of Tissue Morphogenesis (R.D.-H., R.H.A.)
| | - Ralf H Adams
- Max-Planck-Institute for Molecular Biomedicine, Department of Tissue Morphogenesis (R.D.-H., R.H.A.)
| | - Hideo A Baba
- Faculty of Medicine, University of Münster, Germany. Institute of Pathology, University Hospital Essen, University Duisburg-Essen, Germany (H.A.B.)
| | - Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany (H.S.)
| | - Kai Schuh
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Boris V Skryabin
- Core Facility Transgenic Animal and genetic engineering Models (B.V.S.)
| | - Kiavash Movahedi
- Myeloid Cell Immunology Lab, Vesalius Research Center, Center for Inflammation Research, and Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium (K.M.)
| | - Frank Schweda
- Institute of Physiology, University of Regensburg, Germany (A.W., F.S.)
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
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Abstract
Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease that affects the central nervous system (CNS), particularly, in young adults. Current MS treatments aim to reduce demyelination; however, these have limited efficacy, display side effects and lack of regenerative activities. Oligodendrocyte progenitor cells (OPCs) represents the major source for new myelin. Upon demyelination, OPCs get activated, proliferate, migrate towards the lesion, and differentiate into remyelinating oligodendrocytes. Although myelin repair (remyelination) represents a robust response to myelin damage, during MS, this regenerative phenomenon decays in efficiency or even fails. CNS-resident pericytes (CNS-PCs) are essential for vascular homeostasis regulating blood-brain barrier (BBB) permeability and stability as well as endothelial cells (ECs) function during angiogenesis and neovascularization. Recent studies indicate that CNS-PCs also play a crucial role regulating OPC function during remyelination, and very importantly, these cells are substantially affected in MS. This chapter summarizes important aspects of MS and CNS remyelination as well as it provides new insights supporting the contribution of CNS-PCs to myelin regeneration and to MS pathology. Currently, there is evidence arguing in favor of CNS-PCs as novel therapeutic targets for the development of future treatments for MS.
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Lelièvre B, Briet M, Godon C, Legras P, Riou J, Vandeputte P, Diquet B, Bouchara JP. Impact of Infection Status and Cyclosporine on Voriconazole Pharmacokinetics in an Experimental Model of Cerebral Scedosporiosis. J Pharmacol Exp Ther 2018; 365:408-412. [PMID: 29491040 DOI: 10.1124/jpet.117.245449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/15/2018] [Indexed: 11/22/2022] Open
Abstract
Cerebral Scedosporium infections usually occur in lung transplant recipients as well as in immunocompetent patients in the context of near drowning. Voriconazole is the first-line treatment. The diffusion of voriconazole through the blood-brain barrier in the context of cerebral infection and cyclosporine administration is crucial and remains a matter of debate. To address this issue, the pharmacokinetics of voriconazole was assessed in the plasma, cerebrospinal fluid (CSF), and brain in an experimental model of cerebral scedosporiosis in rats receiving or not receiving cyclosporine. A single dose of voriconazole (30 mg/kg, i.v.) was administered to six groups of rats randomized according to the infection status and the cyclosporine dosing regimen (no cyclosporine, a single dose, or three doses; 15 mg/kg each). Voriconazole concentrations in plasma, CSF, and brain samples were quantified using ultra-performance liquid chromatography-tandem mass spectrometry and high-performance liquid chromatography UV methods and were documented up to 48 hours after administration. Pharmacokinetic parameters were estimated using a noncompartmental approach. Voriconazole pharmacokinetic profiles were similar for plasma, CSF, and brain in all groups studied. The voriconazole Cmax and area under the curve (AUC) (AUC0 ≥ 48 hours) values were significantly higher in plasma than in CSF [CSF/plasma ratio, median (range) = 0.5 (0.39-0.55) for AUC0 ≥ 48 hours and 0.47 (0.35 and 0.75) for Cmax]. Cyclosporine administration was significantly associated with an increase in voriconazole exposure in the plasma, CSF, and brain. In the plasma, but not in the brain, an interaction between the infection and cyclosporine administration reduced the positive impact of cyclosporine on voriconazole exposure. Together, these results emphasize the impact of cyclosporine on brain voriconazole exposure.
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Affiliation(s)
- Bénédicte Lelièvre
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Marie Briet
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Charlotte Godon
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Pierre Legras
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Jérémie Riou
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Patrick Vandeputte
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Bertrand Diquet
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
| | - Jean-Philippe Bouchara
- Service de Pharmacologie-Toxicologie-Centre Régional de Pharmacovigilance, Institut de Biologie en Santé (B.L., M.B., B.D.), MITOVASC, UMR CNRS 6214, Inserm 1083, Université d'Angers (M.B.), Micro- et Nanomédecines Biomimétiques, UMR INSERM 1066-CNRS 6021, Université d'Angers (J.R.), and Laboratoire de Parasitologie-Mycologie, Institut de Biologie en Santé (J.-P.B.), Centre Hospitalier Universitaire, Angers, France; Groupe d'Etude des Interactions Hôte-Pathogène (EA 3142), Université d'Angers, Université de Bretagne Occidentale, Institut de Biologie en Santé, Angers, France (B.L., C.G., P.L., P.V., J.-P.B., B.D.); and Service Commun de l'Animalerie Hospitalo-Universitaire, Université d'Angers, Angers, France (P.L.)
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5
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Contribution of thrombin-reactive brain pericytes to blood-brain barrier dysfunction in an in vivo mouse model of obesity-associated diabetes and an in vitro rat model. PLoS One 2017; 12:e0177447. [PMID: 28489922 PMCID: PMC5425209 DOI: 10.1371/journal.pone.0177447] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 04/27/2017] [Indexed: 12/14/2022] Open
Abstract
Diabetic complications are characterized by the dysfunction of pericytes located around microvascular endothelial cells. The blood–brain barrier (BBB) exhibits hyperpermeability with progression of diabetes. Therefore, brain pericytes at the BBB may be involved in diabetic complications of the central nervous system (CNS). We hypothesized that brain pericytes respond to increased brain thrombin levels in diabetes, leading to BBB dysfunction and diabetic CNS complications. Mice were fed a high-fat diet (HFD) for 2 or 8 weeks to induce obesity. Transport of i.v.-administered sodium fluorescein and 125I-thrombin across the BBB were measured. We evaluated brain endothelial permeability and expression of tight junction proteins in the presence of thrombin–treated brain pericytes using a BBB model of co-cultured rat brain endothelial cells and pericytes. Mice fed a HFD for 8 weeks showed both increased weight gain and impaired glucose tolerance. In parallel, the brain influx rate of sodium fluorescein was significantly greater than that in mice fed a normal diet. HFD feeding inhibited the decline in brain thrombin levels occurring during 6 weeks of feeding. In the HFD fed mice, plasma thrombin levels were significantly increased, by up to 22%. 125I-thrombin was transported across the BBB in normal mice after i.v. injection, with uptake further enhanced by co-injection of unlabeled thrombin. Thrombin-treated brain pericytes increased brain endothelial permeability and caused decreased expression of zona occludens-1 (ZO-1) and occludin and morphological disorganization of ZO-1. Thrombin also increased mRNA expression of interleukin-1β and 6 and tumor necrosis factor-α in brain pericytes. Thrombin can be transported from circulating blood through the BBB, maintaining constant levels in the brain, where it can stimulate pericytes to induce BBB dysfunction. Thus, the brain pericyte–thrombin interaction may play a key role in causing BBB dysfunction in obesity-associated diabetes and represent a therapeutic target for its CNS complications.
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Nippert AR, Biesecker KR, Newman EA. Mechanisms Mediating Functional Hyperemia in the Brain. Neuroscientist 2017; 24:73-83. [PMID: 28403673 DOI: 10.1177/1073858417703033] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuronal activity within the brain evokes local increases in blood flow, a response termed functional hyperemia. This response ensures that active neurons receive sufficient oxygen and nutrients to maintain tissue function and health. In this review, we discuss the functions of functional hyperemia, the types of vessels that generate the response, and the signaling mechanisms that mediate neurovascular coupling, the communication between neurons and blood vessels. Neurovascular coupling signaling is mediated primarily by the vasoactive metabolites of arachidonic acid (AA), by nitric oxide, and by K+. While much is known about these pathways, many contentious issues remain. We highlight two controversies, the role of glial cell Ca2+ signaling in mediating neurovascular coupling and the importance of capillaries in generating functional hyperemia. We propose signaling pathways that resolve these controversies. In this scheme, capillary dilations are generated by Ca2+ increases in astrocyte endfeet, leading to production of AA metabolites. In contrast, arteriole dilations are generated by Ca2+ increases in neurons, resulting in production of nitric oxide and AA metabolites. Arachidonic acid from neurons also diffuses into astrocyte endfeet where it is converted into additional vasoactive metabolites. While this scheme resolves several discrepancies in the field, many unresolved challenges remain and are discussed in the final section of the review.
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Affiliation(s)
- Amy R Nippert
- 1 Department of Neuroscience, University of Minnesota-Twin Cities, Minneapolis, MN, USA
| | - Kyle R Biesecker
- 1 Department of Neuroscience, University of Minnesota-Twin Cities, Minneapolis, MN, USA
| | - Eric A Newman
- 1 Department of Neuroscience, University of Minnesota-Twin Cities, Minneapolis, MN, USA
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Role of thrombin-PAR1-PKCθ/δ axis in brain pericytes in thrombin-induced MMP-9 production and blood-brain barrier dysfunction in vitro. Neuroscience 2017; 350:146-157. [PMID: 28344073 DOI: 10.1016/j.neuroscience.2017.03.026] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 03/09/2017] [Accepted: 03/14/2017] [Indexed: 02/08/2023]
Abstract
Thrombin, an essential component in the coagulation cascade, participates in the pathogenesis of brain diseases, such as ischemic stroke, intracerebral hemorrhage, Alzheimer's disease and Parkinson's disease through blood-brain barrier (BBB) dysfunction. It is thought that the thrombin-matrix metalloproteinase (MMP)-9 axis is an important process in the pathogenesis of neurovascular disease, such as BBB dysfunction. We recently reported that brain pericytes are the most MMP-9-releasing cells in response to thrombin stimulation among the BBB-constituting cells. This thrombin-induced MMP-9 release is partially due to protease-activated receptor (PAR1), one of the specific thrombin receptors. Then, we evaluated the intracellular signaling pathways involved in MMP-9 release and the contribution of thrombin-reactive brain pericytes to BBB dysfunction. PKC activator evoked MMP-9 release from brain pericytes. The thrombin-induced MMP-9 release was inhibited by U0126, LY294002, Go6976, and Go6983. However, Go6976 decreased phosphorylation levels of PKCθ and Akt, and Go6983 decreased phosphorylation levels of PKCδ and extracellular signal-regulated kinase (ERK). Additionally, treatment of pericytes with thrombin or PAR1-activating peptide stimulated PKCδ/θ signaling. These substances impaired brain endothelial barrier function in the presence of brain pericytes. Brain pericytes function through two independent downstream signaling pathways via PAR1 activation to release MMP-9 in response to thrombin - the PKCθ-Akt pathway and the PKCδ-ERK1/2 pathway. These pathways participate in PAR1-mediated MMP-9 release from pericytes, which leads to BBB dysfunction. Brain pericytes and their specific signaling pathways could provide novel therapeutic targets for thrombin-induced neurovascular diseases.
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8
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Marina N, Kasymov V, Ackland GL, Kasparov S, Gourine AV. Astrocytes and Brain Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:201-7. [PMID: 27343098 DOI: 10.1007/978-1-4899-7678-9_14] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astrocytes provide the structural and functional interface between the cerebral circulation and neuronal networks. They enwrap all intracerebral arterioles and capillaries, control the flux of nutrients as well as the ionic and metabolic environment of the neuropil. Astrocytes have the ability to adjust cerebral blood flow to maintain constant PO2 and PCO2 of the brain parenchyma. Release of ATP in the brainstem, presumably by local astrocytes, helps to maintain breathing and counteract hypoxia-induced depression of the respiratory network. Astrocytes also appear to be involved in mediating hypoxia-evoked changes in blood-brain barrier permeability, brain inflammation, and neuroprotection against ischaemic injury. Thus, astrocytes appear to play a fundamental role in supporting neuronal function not only in normal conditions but also in pathophysiological states when supply of oxygen to the brain is compromised.
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Affiliation(s)
- Nephtali Marina
- Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Vitaliy Kasymov
- Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Gareth L Ackland
- Experimental Medicine, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Sergey Kasparov
- Department of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - Alexander V Gourine
- Neuroscience, Physiology & Pharmacology, University College London, London, UK.
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Machida T, Takata F, Matsumoto J, Takenoshita H, Kimura I, Yamauchi A, Dohgu S, Kataoka Y. Brain pericytes are the most thrombin-sensitive matrix metalloproteinase-9-releasing cell type constituting the blood-brain barrier in vitro. Neurosci Lett 2015; 599:109-14. [PMID: 26002077 DOI: 10.1016/j.neulet.2015.05.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 05/11/2015] [Accepted: 05/15/2015] [Indexed: 12/22/2022]
Abstract
In the acute phase of intracerebral hemorrhage (ICH), hemorrhagic transformation and brain edema are associated with blood-brain barrier (BBB) disruption. Elevated levels of thrombin, a coagulation factor, contribute to the development of brain edema during ICH through matrix metalloproteinase (MMP)-9 production. Thrombin directly induces a variety of cellular responses through its specific receptors known as protease-activated receptors (PARs). However, it remains unclear which cell types constituting the BBB mainly produce MMP-9 in response to thrombin. Here, we compared the MMP-9 release induced by thrombin using primary cultures of rat brain microvascular endothelial cells, astrocytes, and pericytes. Brain pericytes exhibited the highest levels of MMP-9 release due to thrombin stimulation among the BBB cells. The pattern of PAR mRNA expression in pericytes was characterized by high expression of PAR1 and moderate expression of PAR4. Heat-inactivated thrombin failed to stimulate pericytes to release MMP-9. A selective PAR1 inhibitor SCH79797 blocked the thrombin-induced MMP-9 release from pericytes. These findings suggest that both PAR1 and PAR4 mediate thrombin-induced MMP-9 release from pericytes. The present study raises the possibility that brain pericytes could play a pivotal role as a highly thrombin-sensitive and MMP-9-producing cell type at the BBB in brain damage including ICH.
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Affiliation(s)
- Takashi Machida
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Fuyuko Takata
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan; BBB Laboratory, PharmaCo-Cell Co., Ltd., Nagasaki, Japan
| | - Junichi Matsumoto
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Hisayo Takenoshita
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Ikuya Kimura
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Atsushi Yamauchi
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Shinya Dohgu
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Yasufumi Kataoka
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan; BBB Laboratory, PharmaCo-Cell Co., Ltd., Nagasaki, Japan.
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10
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Ji Y, Chen S, Xu C, Li L, Xiang B. The use of propranolol in the treatment of infantile haemangiomas: an update on potential mechanisms of action. Br J Dermatol 2014; 172:24-32. [PMID: 25196392 DOI: 10.1111/bjd.13388] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2014] [Indexed: 02/05/2023]
Abstract
Currently, propranolol is the preferred treatment for problematic proliferating infantile haemangiomas (IHs). The rapid action of propranolol has been shown to be especially dramatic in IHs involving dyspnoea, haemodynamic compromise, palpebral occlusion or ulceration. Another remarkable aspect of propranolol treatment revealed that the growth of the IHs was not only stabilized, but also that the improvement continued until complete involution was achieved, leading to a considerable shortening of the natural course of IH. However, the mechanisms underlying the effects of propranolol have not been fully elucidated. Recent studies have offered evidence of a variety of mechanisms. These include the promotion of pericyte-mediated vasoconstriction, the inhibition of vasculogenesis and catecholamine-induced angiogenesis, the disruption of haemodynamic force-induced cell survival, and the inactivation of the renin-angiotensin system. This review summarizes these mechanisms and the new concepts that are emerging in this area of research. Moreover, several molecular mechanisms by which propranolol may modify neovascularization in IH have also been proposed. The antihaemangioma effect of propranolol may not be attributable to a single mechanism, but rather to a combination of events that have not yet been elucidated or understood. Further studies are needed to evaluate and verify these mechanisms to gain a greater understanding of the effects of the intake of propranolol on haemangioma involution.
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Affiliation(s)
- Y Ji
- Division of Oncology, Department of Pediatric Surgery, West China Hospital of Sichuan University, Chengdu, 610041, China
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11
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Leite LN, Gonzaga NA, Tirapelli DPC, Tirapelli LF, Tirapelli CR. Pharmacological characterization of the relaxant effect induced by adrenomedullin in rat cavernosal smooth muscle. Braz J Med Biol Res 2014; 47:876-85. [PMID: 25140812 PMCID: PMC4181223 DOI: 10.1590/1414-431x20143911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/09/2014] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to determine the mechanisms underlying the relaxant
effect of adrenomedullin (AM) in rat cavernosal smooth muscle (CSM) and the
expression of AM system components in this tissue. Functional assays using standard
muscle bath procedures were performed in CSM isolated from male Wistar rats. Protein
and mRNA levels of pre-pro-AM, calcitonin receptor-like receptor (CRLR), and Subtypes
1, 2 and 3 of the receptor activity-modifying protein (RAMP) family were assessed by
Western immunoblotting and quantitative real-time polymerase chain reaction,
respectively. Nitrate and 6-keto-prostaglandin F1α
(6-keto-PGF1α; a stable product of prostacyclin) levels were determined
using commercially available kits. Protein and mRNA of AM, CRLR, and RAMP 1, -2, and
-3 were detected in rat CSM. Immunohistochemical assays demonstrated that AM and CRLR
were expressed in rat CSM. AM relaxed CSM strips in a concentration-dependent manner.
AM22-52, a selective antagonist for AM receptors, reduced the
relaxation induced by AM. Conversely, CGRP8-37, a selective antagonist for
calcitonin gene-related peptide receptors, did not affect AM-induced relaxation.
Preincubation of CSM strips with NG-nitro-L-arginine-methyl-ester (L-NAME,
nitric oxide synthase inhibitor), 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ,
quanylyl cyclase inhibitor), Rp-8-Br-PET-cGMPS (cGMP-dependent protein kinase
inhibitor), SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazole,
selective cyclooxygenase-1 inhibitor], and 4-aminopyridine (voltage-dependent
K+ channel blocker) reduced AM-induced relaxation. On the other hand,
7-nitroindazole (selective neuronal nitric oxide synthase inhibitor), wortmannin
(phosphatidylinositol 3-kinase inhibitor), H89 (protein kinase A inhibitor), SQ22536
[9-(tetrahydro-2-furanyl)-9H-purin-6-amine, adenylate cyclase inhibitor],
glibenclamide (selective blocker of ATP-sensitive K+ channels), and apamin
(Ca2+-activated channel blocker) did not affect AM-induced relaxation.
AM increased nitrate levels and 6-keto-PGF1α in rat CSM. The major new
contribution of this research is that it demonstrated expression of AM and its
receptor in rat CSM. Moreover, we provided evidence that AM-induced relaxation in
this tissue is mediated by AM receptors by a mechanism that involves the nitric
oxide-cGMP pathway, a vasodilator prostanoid, and the opening of voltage-dependent
K+ channels.
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Affiliation(s)
- L N Leite
- Programa de Pós-Graduação em Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - N A Gonzaga
- Programa de Pós-Graduação em Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - D P C Tirapelli
- Departamento de Cirurgia e Anatomia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - L F Tirapelli
- Departamento de Cirurgia e Anatomia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - C R Tirapelli
- Laboratório de Farmacologia, Departamento de Enfermagem Psiquiátrica e Ciências Humanas, Escola de Enfermagem de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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12
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Mao Y, Su J, Lei L, Meng L, Qi Y, Huo Y, Tang C. Adrenomedullin and adrenotensin increase the transcription of regulator of G‑protein signaling 2 in vascular smooth muscle cells via the cAMP‑dependent and PKC pathways. Mol Med Rep 2013; 9:323-7. [PMID: 24154573 DOI: 10.3892/mmr.2013.1751] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 10/01/2013] [Indexed: 11/06/2022] Open
Abstract
The regulator of G‑protein signaling 2 (RGS2) has been shown to be crucial in the regulation of vascular tone and blood pressure. The vascular activities of adrenomedullin (ADM) and adrenotension (ADT), two natural peptides, are dependent upon the modulation of RGS2 expression. However, the effects and pathways involved in their modulation remain unknown. This study aimed to observe the changes of RGS2 expression in response to ADM and ADT in cultured vascular smooth muscle cells and to clarify the potential signaling pathways in vitro. In the present study, vascular smooth muscle cells (VSMCs) were cultured with ADM and ADT of various concentrations for different time periods, and the gene expression of RGS2 was analyzed by PCR. ADM significantly increased the gene expression at 0.5 h to ~35‑fold of that at baseline, whereas ADT marginally increased the expression after 1‑2 h. SQ22,536 and chelerythrine were used to block the protein kinase A (PKA) and PKC pathways activated by incubation with ADM. The gene expression of RGS2 was reduced by SQ22,536 only. Furthermore, when SQ22,536 and chelerythrine were added to the cells incubated with ADT, the gene expression was markedly reduced by both SQ22,536 and chelerythrine. In conclusion, ADM immediately showed a marked increase in the gene expression of RGS2 in cultured VSMCs via a cAMP‑dependent pathway and ADT gradually showed a marginal increase in the gene expression via a cAMP‑dependent pathway and a PKC pathway.
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Affiliation(s)
- Yuanjie Mao
- Department of Cardiology, Peking University First Hospital, Beijing 100034, P.R. China
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13
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Takata F, Dohgu S, Yamauchi A, Matsumoto J, Machida T, Fujishita K, Shibata K, Shinozaki Y, Sato K, Kataoka Y, Koizumi S. In vitro blood-brain barrier models using brain capillary endothelial cells isolated from neonatal and adult rats retain age-related barrier properties. PLoS One 2013; 8:e55166. [PMID: 23383092 PMCID: PMC3561369 DOI: 10.1371/journal.pone.0055166] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 12/19/2012] [Indexed: 11/18/2022] Open
Abstract
The blood-brain barrier (BBB) restricts the entry of circulating drugs and xenobiotics into the brain, and thus its permeability to substances is a critical factor that determines their central effects. The infant brain is vulnerable to neurotoxic substances partly due to the immature BBB. The employment of in vitro BBB models to evaluate permeability of compounds provides higher throughput than that of in vivo animal experiments. However, existing in vitro BBB models have not been able to simulate the intrinsic neonatal BBB. To establish a neonatal BBB model that mimics age-related BBB properties, the neonatal and adult in vitro BBB models were constructed with brain endothelial cells isolated from 2- and 8-week-old rats, respectively. To evaluate BBB functions, transendothelial electrical resistance, permeability of sodium fluorescein and Evans blue-albumin, and transport of rhodamine123 were measured. Radiolabelled drugs were used for BBB permeability studies in the neonatal and adult BBB models (in vitro) and in age-matched rats (in vivo). The neonatal BBB model showed lower barrier and p-glycoprotein (P-gp) functions than the adult BBB model; these were well associated with lower expressions of the barrier-related proteins and P-gp, and a different distribution pattern of immunostained barrier-related proteins. Verapamil (a P-gp inhibitor) significantly increased the influx of rhodamine 123, supporting functional P-gp expression in the neonatal BBB model. Valproic acid, but not nicotine, showed higher BBB permeability in the neonatal BBB model, which was well in accordance with the in vivo BBB property. We established a neonatal BBB model in vitro. This could allow us to assess the age-dependent BBB permeability of drugs.
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Affiliation(s)
- Fuyuko Takata
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
- BBB Laboratory, PharmaCo-Cell Co., Ltd., Nagasaki, Japan
| | - Shinya Dohgu
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Atsushi Yamauchi
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Junichi Matsumoto
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Takashi Machida
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Kayoko Fujishita
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
| | - Keisuke Shibata
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
- Japan Science and Technology Agency, Core Research for Evolutional Science and Technology, Tokyo, Japan
| | - Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
- Japan Science and Technology Agency, Core Research for Evolutional Science and Technology, Tokyo, Japan
| | - Kaoru Sato
- Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan
| | - Yasufumi Kataoka
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
- BBB Laboratory, PharmaCo-Cell Co., Ltd., Nagasaki, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
- Japan Science and Technology Agency, Core Research for Evolutional Science and Technology, Tokyo, Japan
- * E-mail:
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14
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Wang D, Ruan L, Hong Y, Chabot JG, Quirion R. Involvement of PKA-dependent upregulation of nNOS-CGRP in adrenomedullin-initiated mechanistic pathway underlying CFA-induced response in rats. Exp Neurol 2012; 239:111-9. [PMID: 23063906 DOI: 10.1016/j.expneurol.2012.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 09/30/2012] [Accepted: 10/04/2012] [Indexed: 11/28/2022]
Abstract
We have previously shown that intrathecal administration of the adrenomedullin (AM) receptor antagonist AM(22-52) produces a long-lasting anti-hyperalgesia effect. This study examined the hypothesis that AM recruits other pronociceptive mediators in complete Freund's adjuvant (CFA)-induced inflammation. Injection of CFA in the hindpaw of rat produced an increase in the expression of nNOS in dorsal root ganglion (DRG) and the spinal dorsal horn. An intrathecal administration of AM(22-52), but not the CGRP antagonist BIBN4096BS, abolished the CFA-induced increase of nNOS. Moreover, AM-induced increase of CGRP was inhibited by the nNOS inhibitors L-NAME and 7-nitroindazole in cultured ganglion explants. Addition of AM to ganglion cultures induced an increase in nNOS protein, which was attenuated by the PKA inhibitor H-89. Treatment with AM also concentration-dependently increased cAMP content and pPKA protein level, but not its non-phosphorylated form, in cultured ganglia. In addition, nNOS was shown to be co-localized with the AM receptor components calcitonin receptor-like receptor and receptor activity-modifying protein 2- and 3 in DRG neurons. The present study suggests that the enhanced activity of nitric oxide (NO) mediates the biological action of AM at the spinal level and that AM recruits NO-CGRP via cAMP/PKA signaling in a mechanistic pathway underlying CFA-induced hyperalgesia.
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Affiliation(s)
- Dongmei Wang
- Provincial Key Laboratory of Developmental Biology and Neuroscience, Fujian Normal University, Fuzhou, Fujian, 350108, China
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15
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Duchemin S, Boily M, Sadekova N, Girouard H. The complex contribution of NOS interneurons in the physiology of cerebrovascular regulation. Front Neural Circuits 2012; 6:51. [PMID: 22907993 PMCID: PMC3414732 DOI: 10.3389/fncir.2012.00051] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 07/19/2012] [Indexed: 12/23/2022] Open
Abstract
Following the discovery of the vasorelaxant properties of nitric oxide (NO) by Furchgott and Ignarro, the finding by Bredt and coll. of a constitutively expressed NO synthase in neurons (nNOS) led to the presumption that neuronal NO may control cerebrovascular functions. Consequently, numerous studies have sought to determine whether neuraly-derived NO is involved in the regulation of cerebral blood flow (CBF). Anatomically, axons, dendrites, or somata of NO neurons have been found to contact the basement membrane of blood vessels or perivascular astrocytes in all segments of the cortical microcirculation. Functionally, various experimental approaches support a role of neuronal NO in the maintenance of resting CBF as well as in the vascular response to neuronal activity. Since decades, it has been assumed that neuronal NO simply diffuses to the local blood vessels and produce vasodilation through a cGMP-PKG dependent mechanism. However, NO is not the sole mediator of vasodilation in the cerebral microcirculation and is known to interact with a myriad of signaling pathways also involved in vascular control. In addition, cerebrovascular regulation is the result of a complex orchestration between all components of the neurovascular unit (i.e., neuronal, glial, and vascular cells) also known to produce NO. In this review article, the role of NO interneuron in the regulation of cortical microcirculation will be discussed in the context of the neurovascular unit.
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Affiliation(s)
- Sonia Duchemin
- Department of Pharmacology, Université de Montréal Montreal, QC, Canada
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16
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Takata F, Dohgu S, Matsumoto J, Takahashi H, Machida T, Wakigawa T, Harada E, Miyaji H, Koga M, Nishioku T, Yamauchi A, Kataoka Y. Brain pericytes among cells constituting the blood-brain barrier are highly sensitive to tumor necrosis factor-α, releasing matrix metalloproteinase-9 and migrating in vitro. J Neuroinflammation 2011; 8:106. [PMID: 21867555 PMCID: PMC3182916 DOI: 10.1186/1742-2094-8-106] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 08/26/2011] [Indexed: 01/28/2023] Open
Abstract
Background Increased matrix metalloproteinase (MMP)-9 in the plasma and brain is associated with blood-brain barrier (BBB) disruption through proteolytic activity in neuroinflammatory diseases. MMP-9 is present in the brain microvasculature and its vicinity, where brain microvascular endothelial cells (BMECs), pericytes and astrocytes constitute the BBB. Little is known about the cellular source and role of MMP-9 at the BBB. Here, we examined the ability of pericytes to release MMP-9 and migrate in response to inflammatory mediators in comparison with BMECs and astrocytes, using primary cultures isolated from rat brains. Methods The culture supernatants were collected from primary cultures of rat brain endothelial cells, pericytes, or astrocytes. MMP-9 activities and levels in the supernatants were measured by gelatin zymography and western blot, respectively. The involvement of signaling molecules including mitogen-activated protein kinases (MAPKs) and phosphoinositide-3-kinase (PI3K)/Akt in the mediation of tumor necrosis factor (TNF)-α-induced MMP-9 release was examined using specific inhibitors. The functional activity of MMP-9 was evaluated by a cell migration assay. Results Zymographic and western blot analyses demonstrated that TNF-α stimulated pericytes to release MMP-9, and this release was much higher than from BMECs or astrocytes. Other inflammatory mediators [interleukin (IL)-1β, interferon-γ, IL-6 and lipopolysaccharide] failed to induce MMP-9 release from pericytes. TNF-α-induced MMP-9 release from pericytes was found to be mediated by MAPKs and PI3K. Scratch wound healing assay showed that in contrast to BMECs and astrocytes the extent of pericyte migration was significantly increased by TNF-α. This pericyte migration was inhibited by anti-MMP-9 antibody. Conclusion These findings suggest that pericytes are most sensitive to TNF-α in terms of MMP-9 release, and are the major source of MMP-9 at the BBB. This pericyte-derived MMP-9 initiated cellular migration of pericytes, which might be involved in pericyte loss in the damaged BBB.
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Affiliation(s)
- Fuyuko Takata
- Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
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Attwell D, Buchan AM, Charpak S, Lauritzen M, Macvicar BA, Newman EA. Glial and neuronal control of brain blood flow. Nature 2010; 468:232-43. [PMID: 21068832 PMCID: PMC3206737 DOI: 10.1038/nature09613] [Citation(s) in RCA: 1665] [Impact Index Per Article: 118.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches.
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Affiliation(s)
- David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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18
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Cyclosporin A induces hyperpermeability of the blood-brain barrier by inhibiting autocrine adrenomedullin-mediated up-regulation of endothelial barrier function. Eur J Pharmacol 2010; 644:5-9. [PMID: 20553921 DOI: 10.1016/j.ejphar.2010.05.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 04/28/2010] [Accepted: 05/25/2010] [Indexed: 01/18/2023]
Abstract
Cyclosporin A, a potent immunosuppressant, can often produce neurotoxicity in patients, although its penetration into the brain is restricted by the blood-brain barrier (BBB). Brain pericytes and astrocytes, which are periendothelial accessory structures of the BBB, can be involved in cyclosporin A-induced BBB disruption. However, the mechanism by which cyclosporin A causes BBB dysfunction remains unknown. Here, we show that in rodent brain endothelial cells, cyclosporin A decreased transendothelial electrical resistance (TEER) by inhibiting intracellular signal transduction downstream of adrenomedullin, an autocrine regulator of BBB function. Cyclosporin A stimulated adrenomedullin release from brain endothelial cells, but did not affect binding of adrenomedullin to its receptors. This cyclosporin A-induced decrease in TEER was attenuated by exogenous addition of adrenomedullin. Cyclosporin A dose-dependently decreased the total cAMP concentration in brain endothelial cells. A combination of cyclosporin A (1microM) with an adenylyl cyclase inhibitor, 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ22536; 10microM), or a protein kinase A (PKA) inhibitor, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H89; 1microM), markedly increased sodium fluorescein permeability in brain endothelial cells, whereas each drug alone had no effect. Thus, these data suggest that cyclosporin A inhibits the adenylyl cyclase/cyclic AMP/PKA signaling pathway activated by adrenomedullin, leading to impairment of brain endothelial barrier function.
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Hamilton NB, Attwell D, Hall CN. Pericyte-mediated regulation of capillary diameter: a component of neurovascular coupling in health and disease. FRONTIERS IN NEUROENERGETICS 2010; 2. [PMID: 20725515 PMCID: PMC2912025 DOI: 10.3389/fnene.2010.00005] [Citation(s) in RCA: 344] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 04/28/2010] [Indexed: 12/18/2022]
Abstract
Because regional blood flow increases in association with the increased metabolic demand generated by localized increases in neural activity, functional imaging researchers often assume that changes in blood flow are an accurate read-out of changes in underlying neural activity. An understanding of the mechanisms that link changes in neural activity to changes in blood flow is crucial for assessing the validity of this assumption, and for understanding the processes that can go wrong during disease states such as ischaemic stroke. Many studies have investigated the mechanisms of neurovascular regulation in arterioles but other evidence suggests that blood flow regulation can also occur in capillaries, because of the presence of contractile cells, pericytes, on the capillary wall. Here we review the evidence that pericytes can modulate capillary diameter in response to neuronal activity and assess the likely importance of neurovascular regulation at the capillary level for functional imaging experiments. We also discuss evidence suggesting that pericytes are particularly sensitive to damage during pathological insults such as ischaemia, Alzheimer's disease and diabetic retinopathy, and consider the potential impact that pericyte dysfunction might have on the development of therapeutic interventions and on the interpretation of functional imaging data in these disorders.
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Affiliation(s)
- Nicola B Hamilton
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
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