Table Of ContentAMINO ACID RECEPTOR RESEARCH
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AMINO ACID RECEPTOR RESEARCH
BENJAMIN F. PALEY
AND
TOMAS E. WARFIELD
EDITORS
Nova Science Publishers, Inc.
New York
Copyright © 2008 by Nova Science Publishers, Inc.
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Library of Congress Cataloging-in-Publication Data
Amino acid receptor research / Benjamin F. Paley and Tomas E. Warfield, editors.
p. ; cm.
Includes bibliographical references and index.
ISBN 978-1-61761-877-2 (Ebook)
Published by Nova Science Publishers, Inc. (cid:30) New York
Contents
Preface vii
Expert Commentary
Interactions between Ligand-Gated Ion Channels: A New
Regulation Mechanism for Fast Synaptic Signaling? 1
Eric Boué-Grabot
Short Communication
A Rapid and Efficient Protocol for Transfecting NMDA Receptor
Channels into Mammalian Cells 9
Patrizia Guida, Paola Gavazzo and Carla Marchetti
Research and Review Studies
Chapter 1 Glutamate Receptors in the Retina: Neurochemical and
Developmental Aspects 17
Roberto Paes-de-Carvalho, Karin da Costa Calaza,
Marcelo Cossenza, Cristiane Rosa Magalhães,
Camila Cabral Portugal and Renato Esteves da Silva Socodato
Chapter 2 Peripheral Glutamate Signalling, Immunity and Pain: Novel
Aspects in Psychoneuroimmunology 67
Helga Susanne Haas
Chapter 3 Insights from Structure-Function Studies of AMPA Receptor
Agonists and Competitive Antagonists 93
Mai Marie Holm, Kimmo Jensen and Jan Egebjerg
Chapter 4 Glutamate Signalling in the Skin 119
Peter M.B. Cahusac
Chapter 5 Regulatory Mechanism of Plasticity at GABA Receptor-Mediated
A
Inhibitory Synapses 133
Shin-ya Kawaguchi and Tomoo Hirano
vi Contents
Chapter 6 GABA R Lateral Mobility and Localization 159
A
Macarena Perán, Ramiro Salas, Juan Antonio Marchal,
Houria Boulaiz, F. Rodríguez-Serrano, Celia Vélez,
Roberto Madeddu, Fidel Hita, Esmeralda Carrillo, Octavio Caba,
Antonio Marínez-Amat, José Carlos Prados, Consolación Melguizo,
Raúl Ortiz, Ana Rama and Antonia Aránega
Chapter 7 The Role of NMDA Glutamate Receptors in Pain and
Anesthetic-Induced Neurodegeneration during Development 185
Xuan Zhang, Tucker A. Patterson, Merle G. Paule, William Slikker
and Cheng Wang
Chapter 8 Spinal Processing of Pain: A Review on NMDA Receptor-Mediated
Activation of Arachidonic Acid and Nitric Oxide Signalling
Pathways 209
I. Lizarraga
Chapter 9 Fragrant Compounds in Foods and Beverages Enhance the GABA
A
Receptor Responses 265
Sheikh Julfikar Hossain and Hitoshi Aoshima
Chapter 10 AMPA Receptor-Mediated Neuronal Death in Motor Neuron
Disease 289
Shin Kwak, Takuto Hideyama and Takenari Yamashita
Chapter 11 Glutamate Receptors Involved in the Interaction between Peripheral
Nerve Terminals 307
Dong-Yuan Cao,Yan Zhao,Yuan Guo and Joel G. Pickar
Chapter 12 Excitotoxicity and White Matter Damage 329
C. Kaur, V. Sivakumar and E.A. Ling
Chapter 13 Regulation of Synaptic Transmission and Brain Function by
Ambient Extracellular Glutamate 347
David E. Featherstone
Chapter 14 Glutamate and Ethanol: The Role of the Ionotropic NMDA
Glutamate Receptors in Alcoholism 363
Justin P. Ridge and Peter R. Dodd
Chapter 15 Chemoreception of Umami in Caterpillars 375
Maciej A. Pszczolkowski
Chapter 16 Glutamate Synapses in Olfactory Neural Circuits 391
Thomas Heinbockel and Philip M. Heyward
Index 427
Preface
Amino acid receptors and cell surface proteins that bind amino acids and trigger changes
which influence the behavior of cells. Glutamate receptors are the most common receptors for
fast excitatory synaptic transmission in the vertebrate central nervous system, and GAMMA-
AMINOBUTYRIC ACID and glycine receptors are the most common receptors for fast
inhibition. This new book presents the latest research in the field.
Expert Commentary - Transmitter-gated ion channels are integral membrane protein
complexes that modulate synaptic neurotransmission directly through the binding of a
transmitter and the opening of a pore permeable to specific ions. Ligand-gated channels can
be divided in three major families: the cys loop receptors including nicotinic, GABA, glycine
and 5-HT3A receptors, glutamate-gated channels (AMPA, NMDA and kainate) and ATP
P2X receptor-channels. In view of the clear structural differences between ligand-gated
channel families, it has been assumed that each receptor type acts independently of the other.
However, recent studies have challenged this principle of independence by showing that the
co-activation of P2X and nicotinic receptors induces a current that is less than the sum of
currents induced by applying the two transmitters separately. Activity-dependent cross-
inhibition was also observed between P2X and 5-HT3A or between several P2X and
2
ionotropic GABA receptors. The close proximity of P2X and α4β2 nicotinic channels, the
2
physical association between P2X and 5-HT3 or GABA gated-channels as well as the
2
involvement of the intracellular domain of both receptors strongly suggested that a molecular
coupling underlies their activity-dependent cross-inhibition. In addition, the interaction
between ATP and GABA-gated channels may also regulate receptor trafficking and targeting.
However, the functional interaction between distinct ligand-gated channels appears to be a
complex molecular process and the identification of the precise underlying mechanisms and
regulatory factors requires further studies. Asymetrical cross-inhibition has also been
observed between AMPA and NMDA receptors and between GABA and glycine receptors,
A
although in the latter case, the interaction was dependent on intracellular phosphorylation
pathways triggered by glycine receptor activation. Therefore, interactions between distinct
ligand-gated channels represent a new mechanism for receptor regulation, which may be
essential for the integration of fast synaptic signaling.
Short Communication - The N-methyl-D-aspartate subtype of glutamate receptor (NR) is
a ligand-gated ionic channel that plays an important role in synaptic plasticity, memory and
spatial learning and is also implicated in the sensitization of pain pathways. For these
properties, it represents a prominent drug target. Research on NR ligands and modulators has
viii Benjamin F. Paley and Tomas E. Warfield
progressed enormously by the use of heterologous cell systems, in which NR complexes of
known composition are selectively expressed. All functional NRs are tetrameric complexes
and contain two copies of the essential subunit NR1 and two copies of any of the four
different NR2s (A, B, C and D); so the heterologous expression of NR channels is
complicated by the requirement for two types of subunit. The expression system of first
choice, RNA-injected Xenopus laevis oocytes, has some drawbacks mainly correlated with
the big dimensions of the cells and their endogenous currents. On the other hand, transfected
mammalian cells represent an ideal model to study biophysical and pharmacological
properties of NR. As permanent transfection is hardly feasible, reliable and efficient protocols
for transient transfection are greatly required. The authors describe here an optimized
protocol we developed for HEK293 cells and that involves the use of an electroporator and
CD8 antibody coated beads to identify transfected cells without the need of a specific assay or
equipment. Their method allows to produce NR expressing cells on a daily basis suitable for
direct electrophysiological investigation and other functional assays.
Chapter 1 - Glutamate is present in several cell types in the retina, including
photoreceptors, bipolar and ganglion cells, constituting a major excitatory pathway in the
tissue. The presence of different classes of metabotropic and ionotropic receptors was
detected since the early stages of development. The chick retina is an excellent model for the
study of neurochemical events during CNS development since many neurotransmitters,
neuromodulators and neuroactive substances found in the brain are also found in this tissue
playing different roles in the mature as in the developing tissue. Moreover, early developing
chick retinal cells can be dissociated and mantained in culture for relatively long periods
where they differentiate many properties of the intact retina. In the present work, the authors
review neurochemical and developmental aspects of glutamate receptors in the chick retina.
Emphasis is given to the following aspects: i) glutamate-induced release of neurotransmitters
and neuroactive substances such as GABA, acetylcholine, adenosine and ascorbate in cultures
of retinal cells; ii) glutamate excitotoxicity in purified cultures of retinal neurons and its
regulation by adenosine and nitric oxide; iii) regulation of protein synthesis and nitric oxide
production by NMDA receptors; iv) transduction pathways involved in glutamate signaling.
The results reveal a complex neurochemical network regulated by glutamate in the
developing and mature retina.
Chapter 2 - The concept of an intricate network of immuno-neuro-endocrine interactions
has evolved in the last 30 years. The scientific field investigating these interactions has been
termed “psychoneuroimmunology”, and it was proposed that the immune system plays a
sensory role, as a “sixth sense”, that detects invaders such as pathogens, antigens, allergens
and tumors with great sensitivity and specificity. In addition, the fact that each of the systems
(i) can produce neurotransmitters, -peptides, hormones, and cytokines, (ii) expresses a
common receptor repertoire, and (iii) shares signal transduction pathways, leads to the
conclusion that the systems use a common chemical language for intra- and inter-systemic
communications. In the last years it became apparent that there are also intimate interactions
between the immune system and glutamate receptor-mediated signalling mechanisms.
Immune cells have been shown to express different types of glutamate receptors as well as
subtypes of the high-affinity glutamate transporter family, similar to observations in other
peripheral tissues. Glutamate and its receptors were found to modulate specific and non-
specific immune functions, as well as neural activity associated with pain conditions.
Furthermore, it was suggested that glutamate may serve as a fast-acting signalling agent
Preface ix
between nerval and immune tissues, providing the basis for a multidirectional flow of
information among the different organ systems within the body. Taken together, these results
indicate that glutamate, besides acting as the major neurotransmitter in the central nervous
system, is also involved in peripheral neuroimmunomodulation, working in a
receptor/transporter-mediated manner. In summary, new insights into these communication
circuits should provide a better understanding of mind-body medicine – a priority for
medicine and human life.
Chapter 3 - The first high resolution structure of an ionotropic glutamate receptor ligand-
binding core was published a decade ago (Armstrong et al., 1998). This discovery was a
breakthrough within the glutamate receptor field and has enabled a cascade of structure-
function studies on the mechanism of action of this receptor family. Insights from these
studies have contributed significantly to the understanding of the series of events coupling
ligand-binding to channel motions for the glutamate receptors, but may also add valuable
input to researchers working with other ligand activated receptors.
This chapter focuses on a line of studies where X-ray analysis has been combined with
electrophysiological studies of a range of ligand-receptor combinations. Here the agonist 2-
amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) has been employed as an
important pharmacological tool due to the large number of substituents, which have been
introduced on the isoxazole ring. This has revealed important information on ligand
selectivity and kinetic properties of the receptor complex. Given that more than fifty
structures of the AMPA receptor ligand-binding domain have been determined, our centre of
attention is the AMPA receptor family, however where appropriate, the authors will correlate
the results to the closely related kainate receptors.
Earlier studies explored the central ligand-binding pocket in order to gain agonist
selectivity. In this chapter the authors describe how recent efforts resulted in ligands that
protruded out from the AMPA binding site and reached into a novel sub-domain to obtain
highly subunit selective agonists.
Important information has also been obtained on the desensitization mechanism. It was
recently revealed that desensitization results from a disruption of the interactions between the
upper parts of the ligand-binding core. The authors speculate that a novel interdomain twist
observed in some crystal structures might facilitate these movements. In addition, they will
discuss the high-resolution structures of AMPA-derived competitive antagonists bound to the
ligand-binding site of the AMPA receptor GluR2.
In this chapter the authors first present a basic introduction to the AMPA receptors
followed by a brief description of the agonist and antagonist induced changes in the receptor
complex. Subsequently, they discuss selected structure-function studies grouped after position
of the substituent in the AMPA isoxazole ring.
Chapter 4 - Many cellular elements of the skin appear to involve glutamate for signalling.
This has been most extensively studied in nociceptive nerve endings (supplied by C and Aδ
fibres). Both ionotropic and metabotropic glutamate receptors are involved in inflammation,
and modulate hyperalgesia and allodynia. Less work has been on low threshold
mechanoreceptors in the skin (supplied by Aβ fibres), although there is clear evidence for a
modulatory role here too. There is evidence that other structural cellular elements, such as
keratinocytes use glutamate for signaling, and may be important for skin growth and wound
healing. Finally, excessive release of glutamate and/or aberrant expression of metabotropic
glutamate receptors may be contributory factors in the development of skin melanomas.
