Glial Neurobiology a Textbook
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Glial Neurobiology A Textbook Alexei Verkhratsky University of Manchester Arthur Butt University of Portsmouth Copyright © 2007 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone +44 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. 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Other Wiley Editorial Offices John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA Wiley-VCH Verlag GmbH, Boschstr. 12, D-69469 Weinheim, Germany John Wiley & Sons Australia Ltd, 33 Park Road, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore 129809 John Wiley & Sons Canada Ltd, 6045 Freemont Blvd, Mississauga, Ontario, L5R 4J3 Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Anniversary Logo Design: Richard J. Pacifico Library of Congress Cataloging in Publication Data Verkhratskii, A. N. (Aleksei Nestorovich) Glial neurobiology : a textbook / Alexei Verkhratsky, Arthur Butt. p. ; cm. Includes bibliographical references and index. ISBN 978-0-470-01564-3 (cloth : alk. paper) 1. Neuroglia. I. Butt, Arthur. II. Title. [DNLM: 1. Neuroglia. WL 102 V519g 2007] QP363.2.V47 2007 611.0188—dc22 2007015819 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 978-0-470-01564-3 (HB) ISBN 978-0-470-51740-6 (PB) Typeset in 10.5/12.5pt Times by Integra Software Services Pvt. Ltd, Pondicherry, India Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production. Contents Preface xi List of abbreviations xiii PART I Physiology of Glia 1 1 Introduction to Glia 3 1.1 Founders of glial research: from Gabriel Valentin to Karl-Ludwig Schleich 3 1.2 Beginning of the modern era 11 1.3 Changing concepts: Glia express molecules of excitation 11 1.4 Glia and neurones in dialogue 12 2 General Overview of Signalling in the Nervous System 13 2.1 Intercellular signalling: Wiring and volume modes of transmission 13 2.2 Intracellular signalling 17 3 Morphology of Glial Cells 21 3.1 Astrocytes 21 3.2 Oligodendrocytes 24 3.3 NG2 expressing glia 26 3.4 Schwann cells 27 3.5 Microglia 28 4 Glial Development 29 4.1 Phylogeny of glia and evolutionary specificity of glial cells in human brain 29 4.2 Macroglial cells 32 4.3 Astroglial cells are brain stem cells 35 4.4 Schwann cell lineage 36 4.5 Microglial cell lineage 37 5 General Physiology of Glial Cells 39 5.1 Membrane potential and ion distribution 39 5.2 Ion channels 39 5.3 Receptors to neurotransmitters and neuromodulators 42 5.4 Glial syncytium – gap junctions 58 viii CONTENTS 5.5 Glial calcium signalling 61 5.6 Neurotransmitter release from astroglial cells 71 5.7 Glial neurotransmitter transporters 76 5.8 Glial cells produce and release neuropeptides 79 5.9 Glial cell derived growth factors 80 6 Neuronal–Glial Interactions 83 6.1 Close apposition of neurones and astroglia: the tripartite synapse 83 6.2 Neuronal–glial synapses 85 6.3 Signalling from neurones to astrocytes 86 6.4 Signalling from astrocytes to neurones 89 6.5 Signalling between oligodendrocytes and neurones 90 6.6 Signalling between Schwann cells and peripheral nerves and nerve endings 90 PART II Glial Cells and Nervous System Function 93 7 Astrocytes 95 7.1 Developmental function – producing new neural cells 96 7.2 Developmental function – neuronal guidance 97 7.3 Regulation of synaptogenesis and control of synaptic maintenance and elimination 99 7.4 Structural function – creation of the functional microarchitecture of the brain 101 7.5 Vascular function – creation of glial–vascular interface (blood–brain barrier) and glia–neurone–vascular units 102 7.6 Regulation of brain microcirculation 105 7.7 Ion homeostasis in the extracellular space 106 7.8 Regulation of extracellular glutamate concentration 112 7.9 Water homeostasis and regulation of the extracellular space volume 114 7.10 Neuronal metabolic support 116 7.11 Astroglia regulate synaptic transmission 119 7.12 Integration in neuronal–glial networks 121 7.13 Astrocytes as cellular substrate of memory and consciousness? 121 8 Oligodendrocytes, Schwann Cells and Myelination 125 8.1 The myelin sheath 127 8.2 Myelination 141 8.3 Myelin and propagation of the action potential 148 PART III Glia and Nervous System Pathology 153 9 General Pathophysiology of Glia 155 9.1 Reactive astrogliosis 155 9.2 Wallerian degeneration 157 9.3 Activation of microglia 160 CONTENTS ix 10 Glia and Diseases of the Nervous System 167 10.1 Alexander’s disease 167 10.2 Spreading depression 167 10.3 Stroke and ischaemia 168 10.4 Cytotoxic brain oedema 178 10.5 Neurodegenerative diseases 180 10.6 Neuropathic pain 185 10.7 Demyelinating diseases 186 10.8 Infectious diseases 187 10.9 Peripheral neuropathies 190 10.10 Psychiatric diseases 192 10.11 Gliomas 194 Conclusions 197 Recommended literature 199 Author Index 207 Subject Index 209 Preface Contemporary understanding of brain organization and function follows the neuronal doctrine, which places the nerve cell and neuronal synaptic contacts at the very centre of the nervous system. This doctrine considers glia as passive supportive cells, which are not involved in the informational exchange, and there- fore secondary elements of the nervous system. In the last few decades, however, our perception of the functional organiza- tion of the brain has been revolutionized. New data forces us to reconsider the main postulate of the neuronal doctrine – that neurones and synapses are the only substrate of integration in the central nervous system. We now learn that astroglial cells, which are the most numerous cells in the brain, literally control the naissance, development, functional activity and death of neuronal circuits. Astroglial cells are in fact the stem elements from which neurones are born. They also create the compartmentalization of the CNS and integrate neurones, synapses, and brain capillaries into inter-dependent functional units. Furthermore, astroglial cells form a functional syncytium, connected through gap junction bridges, which provides an elaborate intercellular communication route. This allows direct translo- cation of ions, metabolic factors and second messengers throughout the CNS, thereby providing a sophisticated means for information exchange. In a way the binary coded electrical communication within neuronal networks may be consid- ered as highly specialized for rapid conveyance of information, whereas astroglial cells may represent the true substance for information processing, integration and storage. Will this truly heretical theory which subordinates neurones to glia be victorious at the end? Forthcoming years hold the answer. When writing this book we have attempted to create a concise yet comprehensive account of glial cells and their role in physiology and pathology of the nervous system. We hope very much that this account may help the reader to discover a fascinating world of brain ‘secondary’ cells, which in fact are essential elements of the nervous system, whose functions and importance are yet to be fully appreciated. Alexei Verkhratsky Arthur Butt List of abbreviations AC adenylate cyclase ACh acetylcholine AIDS acquired immunodeficiency syndrome AMPA -amino-3-hydroxy-5-methyl--isoxazolepropionate AQP aquaporins (water channels) ATP adenosine triphosphate BDNF brain-derived neurotrophic factor BK bradykinin cAMP cyclic adenosine monophosphate cGMP cyclic guanosine monophosphate CaV voltage-gated calcium channels CNP 2,3-cyclic nucleotide-3-phosphodiesterase CNS central nervous system COX cyclooxygenase CSF cerebrospinal fluid DAG diacylglycerol + + 2+ − EK,ENa,ECa,ECl equilibrium potential for K ,Na,Ca and Cl respectively EAAT excitatory amino acid transporter EM electron microscopy ET endothelin GABA -aminobutiric acid GC guanilate cyclase GFAP glial