Дисертації з теми "Récepteurs ionotropiques du glutamate"
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Rossi, Bénédicte. "Les récepteurs ionotropiques du glutamate présynaptiques dans les interneurones de la couche moléculaire du cervelet." Paris 6, 2009. http://www.theses.fr/2009PA066681.
Drian, Marie-Jeanne. "Effets des agonistes et antagonistes des récepteurs ionotropiques du glutamate sur la survie et la différenciation des cellules néopalliales de rat en culture." Paris, EPHE, 2000. http://www.theses.fr/2000EPHE3038.
Piot, Laura. "Nouveaux éléments sur la structure, fonction et pharmacologie des récepteurs delta (GluD)." Thesis, Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS522.pdf.
Ionotropic glutamate receptors (iGluRs) are the main mediators of excitatory transmission in the vertebrate central nervous system (CNS). It has long been considered that the biological responses elicited by iGluRs were necessarily related to the flow of ions through their channel, hence the name "ionotropic". However, many data indicate that several members of this class of receptors can induce intracellular signaling without opening their channel. This is the case of delta receptors, a class comprising two members (GluD1 and GluD2) which plays key roles in synapse formation and the regulation of synaptic transmission through non-ionotropic signaling. However, the molecular mechanisms of GluD receptor function and signaling, as well as their pharmacology, still remain poorly understood, due to a lack of appropriate tools for their study. During my thesis, I developed two methods to study GluD1 receptors: (i) a constitutively open mutant allowing the study of GluD1 by classical cell electrophysiology, and (ii) a fluorescence technique called 'voltage-clamp fluorometry' or VCF to detect in real time local conformational changes within GluD1. These tools offer an unprecedented means to study the pharmacology and molecular mechanisms of signal transduction in this class of receptors. I was thus able to characterize and quantify the sensitivity of GluD1 receptors to a series of synthetic and natural ligands
Ruiz, Arnaud. "Modulation des récepteurs ionotropiques du glutamate par les antagonistes sélectifs et la noradrénaline : études in vivo sur les motoneurones abducens et in vitro dans le néocortex." Aix-Marseille 3, 1998. http://www.theses.fr/1998AIX30065.
Wehbe, Johny. "Analogues du glutamate et de l'aspartate : ligands des récepteurs métabotropiques et inhibiteurs du transport du glutamate." Montpellier 2, 2002. http://www.theses.fr/2002MON20088.
Barbara, Guillaume. "Etudes électrophysiologique et pharmacologique des récepteurs ionotropiques des cellules du lobe antennaire d'abeille, Apis mellifera." Toulouse 3, 2007. http://www.theses.fr/2007TOU30118.
Mangin, Jean-Marie. "Caractérisation fonctionnelle des sous-types du récepteur à la glycine exprimés au cours du développement du système nerveux dans un contexte non-synaptique." Paris 6, 2003. http://www.theses.fr/2003PA066205.
Guillaume, Anaïs. "Vers des analogues gamma, gamma-disubstitués du glutamate comme ligands potentiels des récepteurs métabotropiques du glutamate." Paris 11, 2010. http://www.theses.fr/2010PA114851.
Metabotropic glutamate receptors have received considerable attention over the past decade in view of their relevance in multiple aspects of glutamatergic transmission. The widespread expression of mGluRs through the central nervous system makes these receptors particularly attractives drug targets, and recent studies validate the therapeutic utility of mGluR ligands in neurological and psychiatric disorders such as Alzheimer’s disease, Parkinson’s disease, anxiety, depression and schizophrenia. It is in this context that we were interested in the synthesis of glutamic acid analogues. The first part of this thesis describes the construction of the glutamic acid’s framework. The synthetic approach involves the asymmetric Michael addition of chiral b-enaminoesters to a-substituted Michael acceptors. In the second part, two synthetic pathways to the four diastereomers of our analogues are described. In this approach, the intramolecular cyclization and then the opening of the cycle are the key-steps
Fourgeaud, Lawrence. "Etude de l'endocytose d'un récepteur métabotropique du glutamate : mGluR5." Bordeaux 2, 2003. http://www.theses.fr/2003BOR21010.
Intracellular traffic of neurotransmitter's receptors controls their number and localization at the cell surface, thus modulates the neuronal activity. Synaptic glutamate activates, among others, metabotropic receptors coupled to G-proteins, the mGluRs. We study intracellular trafficking of tagged mGluR5, transfected in cell lines in hippocampal neurons. Using microscopy and biochemistry, we have shown that 1) mGluR5 is expressed in axons and dendrites 2) mGluR5 is stabilized by the cytosolic Homer protein in membrane microdomains 3) mGluR5 is indirectly bound to Dynamin 3 through Homer 4) mGluR5 is constitutively endocytosed by a non-clathrin-coated pits pathway 5) mGluR5 is recycled or degraded depending on the cell type
Jaskolski, Frédéric. "Distribution subcellulaire des récepteurs du glutamate de type kaïnate." Bordeaux 2, 2004. http://www.theses.fr/2004BOR21179.
Glutamate receptors of the kainate type (KA receptors) have recently emerged as key players in the modulation of neuronal network activity. The various roles of KA receptors critically depend on their precise subcellular localization in presynaptic, postsynaptic or extrasynaptic domains. Subcellular localization of KA receptors has been mainly inferred from electrophysiological studies with the help of selective pharmacological tools and KA receptor mutant mice. These studies highlight the diversity of subcellular localization for KA receptors. It is then important to understand the molecular mechanisms underlying the polarized trafficking of KA receptors in distinct neuronal domains. This thesis shed light on the trafficking and membrane delivery of KA receptor subunits isoforms
Bonnot, Agnès. "Etude des générateurs postérieurs de la locomotion chez les mammifères : implication des récepteurs ionotropiques aux acides aminés excitateurs." Bordeaux 1, 1997. http://www.theses.fr/1997BOR10599.
Frauli-El, Agrebi Mélanie. "Les récepteurs métabotropiques du glutamate du groupe III : en quête d'outils pharmacologiques spécifiques." Montpellier 1, 2006. http://www.theses.fr/2006MON1T022.
Colle, Cyril de. "Pharmacologie des récepteurs métabotropiques du glutamate : implication dans la douleur." Montpellier 2, 2000. http://www.theses.fr/2000MON20131.
Chavis, Pascale. "Régulation des canaux calciques par les récepteurs métabotropiques du glutamate." Montpellier 2, 1996. http://www.theses.fr/1996MON20059.
Prézeau, Laurent. "Les récepteurs métabotropiques du glutamate : pharmacologie et mécanismes de transduction." Montpellier 2, 1994. http://www.theses.fr/1994MON20251.
Repak, Emilienne. "Characterization of a novel photo-reversible NMDA receptor-specific agonist for precise temporal control of receptor activation." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066472.
The NMDA-type glutamate receptor (NMDAR) is one of two principal glutamate receptors, the main mediators of excitatory neurotransmission in the central nervous system. NMDARs are critically implicated in synaptic plasticity, the cellular correlate of learning and memory. Although significant advances have been made in understanding the behavior of this receptor, many questions remain. Currently, the state-of-the-art technology for investigating receptor properties in the native environment is caged compounds, which are restricted in their ability to precisely control the spatial and temporal activation of NMDAR due to the diffraction limit of light, which defines the minimum volume of uncaging from whence uncaging molecules diffuse, and the irreversible nature of uncaging. Photoswitchable molecules, by contrast, can rapidly and repeatedly be switched on and off, circumventing the diffusion limitation to permit fine spatial and temporal control of receptor activation. With this in mind, I formed a collaboration with a team of chemists to characterize a novel compound, azobenzene triazole glutamate (ATG), the first photoswitchable compound specific for NMDAR and biologically inert in its thermally stable state. Such a tool holds great promise for finely probing receptor behavior in its native environment. I characterized this compound using one- and two-photon activation, through bath and local application, and through a variety of different experimental paradigms. I demonstrate in detail the properties of this novel compound, propose potential applications of ATG as a novel tool, and suggest possible modifications to optimize future photoswitchable compound design
Sachidhanandam, Shankar. "Rôle des récepteurs kaïnate dans le transfert d'information dans l'hippocampe." Bordeaux 2, 2007. http://www.theses.fr/2007BOR21433.
Kainate receptors (KAR) are ionotropic glutamate receptors implicated in the regulation of synaptic transmission and neuronal excitability. At the mossy fiber (Mf) synapse, KARs can be expressed both pre and postsynaptically. In this study, we examined physiological role of KARs in information transfer at the Mf-CA3 pyramidal cell synapse in the mouse hippocampus. We show that KARs can operate in dual mode, by a direct ionotropic action via GluR6, and an indirect G-protein coupled mechanism requiring the binding of glutamate to KA2, to inhibit the slow afterhyperpolarization (IsAHP), hence enhancing neuronal excitability. Using mice deficient for the various KAR subunits, we show that postsynaptic KARs shape the waveform of unitary EPSPs, and pre and postsynaptic KARs act together to amplify unitary EPSPs, triggering spike discharge under conditions of sustained mossy fiber activity. KARs improve timing precision within a frequency range of 3 to 50 Hz and modulation of IsAHP by KA2 facilitates spike discharge in prolonged stimulus trains. KARs are permissive to the induction of LTP at the associative/commissural input. Physiological patterns of afferent input reproduce the output obtained with controlled stimulus inputs. Hence KARs act as amplifiers of synaptic transmission, to enhance the transfer of information at the Mf-CA3 pyramidal cell synapse
De, Roo Mathias. "Effets modulateurs des neurostéroi͏̈des sur les récepteurs ionotropiques du GABA et de l'ATP dans les neurones sensoriels primaires de rat." Université Louis Pasteur (Strasbourg) (1971-2008), 2004. https://publication-theses.unistra.fr/public/theses_doctorat/2004/DE_ROO_Mathias_2004.pdf.
Veran, Julien. "Etude structure/fonction des récepteurs kaïnate et de leur modulation." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21857/document.
Glutamate released at excitatory synapses acts on ligand-gated ionotropic receptors which fall into three classes: NMDA, AMPA and kainate receptors.At hippocampal mossy fiber synapses onto CA3 pyramidal cells, KARs are present both at the pre- and postsynaptic levels. Postsynaptic KARs are composed of the GluK2, GluK4 and GluK5 subunits, whereas presynaptic KARs are thought to comprise the GluK2 and GluK3 subunits. The functional properties of GluK3 (and GluK2/GluK3) receptors set it apart from the other ionotropic glutamate receptors. In particular, its sensitivity to glutamate is the lowest of all known ionotropic glutamate receptors, due in large part to fast desensitization of receptors with one or two bound glutamate molecules. The low agonist sensitivity of this receptor raises questions about its relevance for synaptic function. Therefore, it is possible that endogenous modulators may potentiate its function.Among potential endogenous modulators of KAR function, we chose to address the role of zinc, because of the large amounts contained in mossy fiber terminals. Zinc is thought to be accumulated into synaptic vesicles, and is co-released with glutamate in the extracellular milieu during neuronal activity. Zinc has been reported to inhibit most of native and recombinant KARs. Despite the proposed role of at hippocampal mossy fiber synapses, although modulation of GluK3-containing KARs by zinc has not yet been addressed.In this study, we show that zinc greatly potentiates recombinant GluK3 receptor currents evoked by glutamate. Zinc markedly slows receptor desensitization and increases apparent affinity for glutamate. Crystallographic studies and analysis of chimeric GluK2/GluK3 KARs and of GluK3 bearing selected point mutations, allowed us to identify the zinc binding domain defined by D759, H762, Q756 and D730, and localized in a region forming the interface between two GluK3 subunits in an LBD dimer assembly. Based on these structure-function studies and on modeling of KAR activity, we show that zinc plays a very distinct role on GluK3-KARs by stabilizing the interaction between dimers of LBD thereby reducing desensitization.Given the proposed localization of GluK3 close to zinc containing synaptic vesicles, zinc may be an endogenous allosteric modulator for native GluK3-KARs, and its binding site a new pharmacological target
Commare, Bruno. "Conception et synthèse de nouveaux agonistes de récepteurs métabotropiques du glutamate." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05P621/document.
Glutamate is the major excitatory neurotransmitter in the central nervous system. It is responsible of the majority of synaptic transmissions. In contrast, this natural amino acid is also involved in numerous neuropathologies and particularly in case of glutamate overconcentration in the synapse. Metabotropic glutamate receptors, that can modulate synaptic transmission, thus constitute promising therapeutic targets. These receptors are divided in three groups and our laboratory has been focused in group III and especially subtypes 4 which own interested properties in symptomatic treatment of pain and Parkinson Disease. The lack of pharmacological tools targeting this receptor prompts us to synthesize novel orthosteric agonist from the hit compound LSP4-2022. This molecule was obtained after several chemical optimizations from (S)-PCEP discovered from virtual screening. During my Ph.D., we could refine the structure-activity relationship of LSP4-2022 synthesizing new fluorinated and heterocyclic derivatives. Besides, a second study was carried out to identify the configuration of the two diastereomers which form tested compounds
Sourdet, Valérie. "Régulation de l'excitabilité des neurones pyramidaux de la couche V du cortex sensori-moteur de rat par les récepteurs métabotropiques du glutamate." Aix-Marseille 2, 2002. http://www.theses.fr/2002AIX22081.
Sibille, Pauline. "Synthèse d'agonistes des récepteurs métabotropiques du glutamate du groupe III : applications thérapeutiques." Paris 5, 2005. http://www.theses.fr/2005PA05P605.
Bessis, Anne-Sophie. "Construction et validation d'un modèle d'activation des récepteurs métabotropiques du glutamate (mGluR)." Paris 5, 2002. http://www.theses.fr/2002PA05P608.
Metabotropic glutamate receptors (mGluRs) belong to the G-Protein-Coupled-Receptors (GPCR) superfamily that constitute about 1% of human genome. They own seven transmembranar domains, but are distinct from GPCRs of family 1 (rhodopsin-like receptor family) or family 2 (glucagon-like receptor family). In fact, the eight human mGluRs form a new GPCR family , family 3 and display a few singularities. For example, these proteins possess a large extracellular domain, which binds the natural ligand glutamate. According to low sequence homologies detected between this domain and bacterial periplasmic proteins, LIVBP, LBP (Leucine/Isoleucine/Valine Binding Protein and Leucine Binding Protein), a structural model of this domain has been built by homology modeling and the glutamate binding site of mGluRs has been identified. Structurally, this domain folds into two lobes that open and close as a clamshell. Functionnally, this study led us to conclude that the the closure of the two lobes, which is stabilized by glutamate fixation, is necessary for mGluR activity. .
Léveillé, Frédéric. "Mécanismes cellulaires et moléculaires impliqués dans la neurotoxicité du glutamate au cours d’atteintes cérébrales aiguë et chronique." Caen, 2006. http://www.theses.fr/2006CAEN2089.
In the mature nervous system, N-methyl-D-aspartate receptors (NMDARs) are critical for synaptic plasticity that may underlie learning and memory. On another hand, excessive activation of NMDARs has been described as a common source of neuronal damage during stroke or chronic neurodegenerative diseases. In the present study, we investigated the consequence of selective activation of synaptic or extrasynaptic NMDARs on several features of excitotoxicity: calcium overload, mitochondrial function, morphological alteration and neuronal death. The results indicate that if NMDARs can still be consider as a major contributor for excitotoxicity, only those located extrasynaptically do induce the cellular disruption leading to neuronal death. In Alzheimer’s disease (AD), an age-dependent neurodegenerative disease, the loss and/or the dysfunction of synapses strongly correlates with the progressive cognitive decline that characterizes this pathology. Abnormal production of amyloid beta (Aβ) peptides is believed to exert a causative role in the pathophysiolology of the disease but the mechanism by which Aβ affects synaptic plasticity remains unclear. Here, we show that exposure to low concentrations of Aβ oligomers induces a rapid structural modification in the dendritic spines of cortical neurons. These modifications induce functional alterations of the excitatory synapses associated with reduction of the synaptic NMDARs responses and increased extrasynaptic NMDARs responses. Taken together, these results revealed a new molecular mechanism that may underlie early synaptic dysfunction induced by Aβ in AD
Papouin, Thomas. "Contrôle des récepteurs du glutamate de type NMDA par leur site co-agoniste." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21832/document.
N-methyl D-aspartate receptors (NMDARs) are central to many aspects of brain physiology and pathology, which they impact differently depending on their synaptic or extrasynaptic location, respectively. In addition to glutamate, they are gated by the necessary binding of a co-agonist on the so-called ‘glycine-binding site’. However, very little is known about the rules that govern the control of NMDARs through this site, in situ. Evidence now suggests that astrocytes could play a critical role in controlling NMDARs activity, in particular through the release of the gliotransmitter D-serine. In the present work, we aimed at understanding how NMDARs are endogenously controlled through their co-agonist binding site, in the CA1 region of rat hippocampus. We primarily focused on the role of two endogenous ligands of this site: glycine and D-serine. We investigated their relative contribution in the control of NMDARs at the different subcellular locations, the dynamics of such control according to synaptic activity, as well as possible changes during post-natal development. Using elecrophysiological approaches, we demonstrate that NMDARs are gated by Dserine, but not glycine, at CA3-CA1 synapses in adults. D-serine is supplied at least in part by surrounding astrocytes in an activity-dependant manner. Its release occurs in response to calcium signalling within the astrocyte and in a vesicular way. Correspondingly, we found astrocytic supply of D-serine to be essential for NMDARs-dependant functions such as synaptic plasticity. In contrast with their synaptic counterparts, extrasynaptic NMDARs are gated by endogenous glycine and not by D-serine. We provide evidence that this compartmentation relies on the differential availability of the two co-agonists at synaptic and extrasynaptic sites. Besides, due to differences in their subunit composition, synaptic and extrasynaptic NMDARs may have preferential affinity for D-serine and glycine respectively. Finally, we show that the control of the NMDAR co-agonist site is developmentally regulated. Early after birth, glycine is the endogenous co-agonist of synaptic NMDARs. The control exerted by D-serine only progressively appears during the first post-natal month, as the switch in NMDARs subunit composition occurs, suggesting a maturation of cellular interactions at the tripartite synapse
Goyet, Elise. "Dynamique et fonction des interactions entre récepteurs du glutamate et de la dopamine." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT019.
In some specific brain areas, synergism between glutamate and dopamine transmission is required to induce synaptic plasticity. Metabotropic glutamate receptor mGlu5 and dopamine receptor D1 are both known to control synaptic plasticity. Moreover, multiple lines of evidence converge toward the ability of G-protein coupled receptors to form dynamic heteromers thereby creating new entities with unique properties. Focusing on the hypothesis of receptor heteromerization, my PhD project aimed at investigating the molecular mechanisms underlying a functional interplay between mGlu5 and D1 receptors.To address this issue, a first part of this work consisted in improving single-cell Bioluminescent Resonance Energy Transfer (BRET) imaging, a technology enabling to study real time protein-protein interaction dynamics in living cells. Using the Nanoluciferase, an extremely bright luciferase, we characterized a faster and higher resolution single-cell BRET imaging technique with unprecedented performance in terms of temporal and spatial resolution, duration of signal stability and signal sensitivity. In the second part of this project, we showed that mGlu5 and D1 can form heteromers in heterologous expression system. The above-mentioned improvements of single-cell BRET imaging technique allowed to evidence the occurrence and the dynamics of mGlu5/D1 heteromers in cultured primary neurons. Furthermore, our results showed that the co-expression of mGlu5 and D1 receptors modifies single receptor properties to favor calcium signaling by increasing mGlu5 constitutive activity and creating a D1 agonist-induced activation of Ca2+ release from intracellular stores.These findings advance our knowledge about the molecular basis of the glutamate/dopamine functional dialogue to control neuronal communication in physiological conditions. Further investigation will help the dissection of the mGlu5/D1 heteromer specific signaling pathway with the hope of defining new therapeutics that may selectively modulate heteromer function and thus bypass undesirable side effects
Manzoni, Olivier. "Messagers intra- et extracellulaires des récepteurs du glutamate dans le système nerveux central." Montpellier 2, 1992. http://www.theses.fr/1992MON20173.
Ruel, Jérôme. "Inhibition tonique de l'activité des fibres du nerf auditif par la dopamine : approche pharmacologique de la première synapse auditive et sa modulation par les efférences latérales." Montpellier 1, 2000. http://www.theses.fr/2000MON1T026.
Sagot, Emmanuelle. "Nouveaux analogues de l'acide glutamique par transamination moléculaire : synthèse et modélisation." Clermont-Ferrand 2, 2007. http://www.theses.fr/2007CLF21788.
Laudenbach, Vincent. "Étude des mécanismes neuroprotecteurs vis-à-vis de l'excitotoxicité glutamatergique cérébrale chez le nouveau-né : influence de trois systèmes neuromodulateurs : opioi͏̈des endogènes, récepteurs noradrénergiques alpha-2 et récepteurs nicotiniques." Paris 6, 2002. http://www.theses.fr/2002PA066210.
Gielen, Marc. "Mécanismes moléculaires du contrôle de l'activité des récepteurs NMDA." Paris 6, 2009. http://www.theses.fr/2009PA066438.
Esmenjaud, Jean-Baptiste. "Dynamique structurale et allostérie des récepteurs NMDA." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE016/document.
Ionotropic glutamate receptors are responsible for the vast majority of fast excitatory neurotransmission in the central nervous system. Among them, NMDA receptors (NMDARs) are key mediators of synaptic plasticity, which is considered as the cellular basis of learning and memory. NMDAR dysfunction is implicated in numerous neurological and psychiatric brain disorders such as Alzheimer and Parkinson’s disease, epilepsy and schizophrenia. NMDAR form massive hetero tetrameric complexes (>500 kDa) endowed with unique allosteric capacity provided by a cluster of eight extracellular clamshell-like domains arranged as two superimposed layers: the Nterminal domain (NTD) layer and the agonist binding domain (ABD) layer. Despite an increasing number of full-length NMDAR structures, the transduction mechanism by which these domains interact in an intact receptor to control its activity remained poorly understood. Combining experimental and in silico analysis, we identify a rolling motion at an interface between the two constitute dimers in the ABD layer as a key determinant in NMDAR activation and modulation pathways. This rotation of the two ABD dimers acts as a conformational switch that tunes channel opening depending on the conformation of the membrane-distal NTD layer. This work unveils how NMDAR domains move and operate in a concerted manner to transduce conformational changes between layers and command receptor activity. It illuminates our understanding of a major synaptic receptor of the central nervous system and paves the way for the development of new pharmacological tools targeting the elucidated allosteric mechanism
Rives, Marie-Laure. "Interaction fonctionnelle entre les récepteurs métabotropiques du glutamate de type 1a (mGluR1a) et les récepteurs métabotropiques de l'acide γ-aminobutyrique (GABA) (GABAB)". Montpellier 2, 2009. http://www.theses.fr/2009MON20006.
G-protein coupled receptors (GPCRs) form the largest membrane receptor family and play critical roles in numerous physiological functions. In contrast to the large number of GPCRs, the number of effectors is considerably smaller, whereas the cellular biological responses are multiple and complex. So, an increasing number of functional interactions have been described and the integration of the signals might be a key event of the signal transduction. Recently, it has been evidenced that signals were generated and controlled through receptorbased signaling complexes, the components of these multi-protein complexes regulating the localization and function of the receptors but it has also been proposed that the ability of these receptors to form dimers or larger order oligomers may provide a way for signal integration. During my PhD, I have been mainly interested in the study of the functional « cross talk » (or regulation) ocurring between mGlu1a and GABAB in Purkinje cells. The co-activation of the GABAB receptor leads to the potentiation of the mGlu1a activation-induced calcium responses. Some results seem to indicate that this potentiation is due to a functional interaction between the implicated signaling pathways but some other data suggested a direct physical interaction between both receptors, that is to say oligomerization. We could demonstrate that a physical interaction between mGlu1a and GABAB was not necessary to the functional « cross talk » observed. This interaction results from a general mechanism in which the beta-gamma subunits produced by the Gi-coupled GABAB receptor enhance the mGlu receptor mediated Gq-response. Most importantly, this mechanism could be generalized to other Gi-Gq pairs of receptors, and the signal integration varies depending on the time delay between the activation of one and the other receptor. Such a mechanism help explaining specific properties of cell expressing two differents Gi and Gq coupled receptors activated by a single transmitter, as well as properties of GPCRs that are naturally coupled to both types of G-proteins
Lopez, Sébastien. "Rôle des récepteurs métabotropiques du glutamate du groupe III dans la maladie de Parkinson." Aix-Marseille 1, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX11023.pdf.
Parkinson’s disease (PD) results from the progressive loss of dopaminergic neurons in the substantia nigra pars compacta that innervate the basal ganglia (BG), a set of subcortical nuclei involved in motor control. In PD, the loss of nigrostriatal dopaminergic neurons is associated with glutamatergic overactivity in the BG. This led to propose therapeutic strategies alternative to L-DOPA treatment, that regulate glutamate action within the BG. Metabotropic glutamate receptors (mGluRs) belonging to group III (mGlu4, mGlu6, mGlu7 et mGlu8) exert presynaptic inhibitory effects on glutamatergic and GABAergic neurotransmission, but the functional involvement of these receptors in regulating BG function is not well defined. We thus have studied the behavioural effects produced by group III receptors agonists, injected in various structures of the BG, to counteract the motor deficits induced by bilateral lesions of dopaminergic nigrostriatal neurons in rats. The motor (related to movement initiation or akinesia) and cognitive deficits (related to motor preparatory processes) induced by dopaminergic lesions were measured in a simple reaction time task developed for rodents and is similar to human tasks. Results show that preferential activation of mGlu4 into the globus pallidus, but not the other group III mGuRs subtypes, reverses the lesion-induced motor deficits. In contrast, activation of mGlu4/8 into the substantia nigra pars reticulata (SNr) enhances lesion-induced motor deficits and produces akinesia in control animals. Moreover, pharmacological blockade of GABA-A receptors into both structures produced similar effects than those observed after group III mGluRs activation, suggesting that a preferential action of these mGlu receptor ligands on GABAergic neurotransmission. In a second part of this work, we show that systemic chronic, but not acute, treatment with a non-subtype selective agonist of group III receptors, ACPT-I, alleviates motor deficits induced by dopaminergic lesions, and produces akinesia in control animals. Analysis of the cellular effects produced by this treatment show that ACPT-I reduces lesion-induced neuronal metabolic hyperactivity in the subthalamic nucleus and SNr. In contrast, in control animals, the same treatment increases metabolic activity in the SNr, thus suggesting that dopaminergic activity triggers group III mGluRs-induced effects. In the last part of this work, we have evaluated the functional interactions between these mGlu and adenosine A2A receptors. Indeed, pharmacological blockade of A2A receptors reduces motor deficits in various PD models. Results show that acute and chronic co-treatment with sub-threshold doses of ACPT-I and various A2A receptor antagonists counteract the cataleptic state induced by the dopaminergic receptor antagonist haloperidol. Altogether, these results demonstrate the involvement of group III mGluRs in regulating motor processes in BG, and suggest that these receptors interact with multiple systems that control their function
Bonfardin, Valérie. "Rôles des récepteurs kaïnate dans le noyau supraoptique de l’hypothalamus de rat." Thesis, Bordeaux 2, 2009. http://www.theses.fr/2009BOR21665/document.
Magnocellular neuroendocrine cells (MNCs) from the supraoptic nucleus (SON) of the hypothalamus synthesize and release the hormones oxytocin (OT) and vasopressin (VP). OT is involved principally in reproductive functions such as parturition and lactation, whereas VP plays a key role in body fluid and cardiovascular homeostasis. The release of OT and VP from the neurohypophysis is controlled by the electrical activity of hypothalamic MNCs, which is itself regulated by GABAergic and glutamatergic synaptic inputs. Presynaptic kainate receptors (KARs) exert a modulatory action on transmitter release in different structures of the central nervous system. This effect can be switched from facilitation to inhibition by an increased concentration of KAR agonists. KAR can also be present postsynaptically where they were shown to participate to the synaptic response in some brain regions. We have demonstrated for the first time that functional KARs were present on GABAergic and glutamatergic inputs as well as on SON neurons. GluR5-containing KARs differentially regulate glutamatergic transmission on OT and VP neurons. Indeed, applications of exogenous agonists of GluR5 induced opposite effects, a facilitatory effect on OT neurons and an inhibitory effect on VP neurons, the latter resulting from an indirect action mediated by postsynaptic GluR5-containing KARs on VP neurons. Thus, activation of these receptors induced the release of a retrograde messenger, probably dynorphin, which in turn act presynaptically to inhibit glutamate release. Regarding the modulation of GABAergic transmission in the SON, we here showed that the increased levels of ambient glutamate associated with the physiological withdrawal of astrocytic processes occuring during lactation could modify the activity of presynaptic KARs. We demonstrated for the first time that a physiological astrocytic plasticity modifies the mode of action of presynaptic KARs from ionotropic to metabotropic, thereby inversing their coupling with GABA release from facilitation into inhibition. The results obtained during my PhD have thus showed that KARs are present both pre-and post-synaptically on adult MNCs. Moreover, KARs differentially regulate OT and VP neurons, which suggest that KARs could play key roles in the regulation of their activity and in physiological processes in which MNCs are involved
Riou, Morgane. "Architecture moléculaire des récepteurs NMDA : Arrangement tétramérique et interfaces entre sous-unités." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01020863.
Vatsa, Parul. "Involvement of a putative glutamate receptor mediated calcium signalling in tobacco : a new link in plant defence." Thesis, Dijon, 2010. http://www.theses.fr/2010DIJOS009.
Glutamate is recognized as the primary excitatory neurotransmitter in the mammalian central nervous system (CNS) but recent studies have shown that glutamate has an important additional immunomodulator role. Glutamate is the ligand of ionotropic glutamate receptors (iGluRs), which are non-selective cation channels (NSCC), permeable to calcium. In plants, animal iGluR homologs were found that were involved in many developmental processes. Here we demonstrate the involvement of putative iGluRs in calcium signalling in response to cryptogein which is a 10 kDa protein secreted by the oomycete Phytophthora cryptogea and is an elicitor of defence in tobacco. Using transformed tobacco cell suspensions expressing aequorin in the cytosol or in the nucleus, our results have shown that glutamate induces a strong and transient [Ca2+]cyt elevation without [Ca2+]nuc changes. Glutamate-induced [Ca2+]cyt elevation was a result of calcium influx from the extracellular medium and was inhibited by different GluR inhibitors. This data suggest the presence of functional calcium channels of GluRs-type in tobacco. Nevertheless, glutamate does not induce some of the calcium-dependent characteristic events of the defence pathways, which are H2O2 production, MAPK activation and hypersensitive response, but promoted NO production. Further, Ca2+ influx,[Ca2+]cyt elevation and NO production induced by cryptogein were shown to be partially inhibited by the glutamate receptor inhibitors, suggesting that cryptogein treatment could activate a calcium channel of the GluR-type leading to plant defense signalling through NO production. We have also demonstrated that cryptogein induces an efflux of glutamate in the apoplast by the process of exocytosis thus activating the GluRs in tobacco. This is the first demonstration for a potential GluR(s) involvement in plant defense signalling, furthermore by mechanisms that showed homology with glutamate effect on neuronal cells
Ango, Jean-Raymond Fabrice. "Adressage fonctionnel des récepteurs métabotropiques du glutamate par les protéines homers dans les neurones." Montpellier 2, 2001. http://www.theses.fr/2001MON20150.
Lachamp, Philippe. "Organisation et mise en place des synapses glutamatergiques dans le noyau du tractus solitaire du rat." Aix-Marseille 3, 2004. http://www.theses.fr/2004AIX30044.
Glutamate is the main excitatory transmitter in the nucleus tractus solitarii (NTS), a sensory relay nucleus which receives visceral afferents. We describe a subpopulation of glutamatergic axon terminals that co-express both vesicular glutamate transporters (VGluT1 and VGluT2) in the rat NTS. We show that this sub-population of terminals originate from visceral afferent fibers. Synaptogenesis in the rat NTS begins before birth. We describe two other periods of synapse formation that take place during the first postnatal month. We show that a proportion of the synapses formed after birth correspond to glutamatergic synapses. We next demonstrate that the GluR2 subunit of the AMPA receptor and the NR1 subunit of the NMDA receptor are both localized within synapses at the onset of synaptogenesis in the rat NTS. No change in localization of the GluR2 subunit occurs with development whereas, in adults, the NR1 subunit is mainly found at extrasynaptic locations
Cahill, Emma. "Integration of dopamine and glutamate signalling by D1R/NMDAR heteromers in the striatum in response to cocaine." Paris 6, 2013. http://www.theses.fr/2013PA066058.
This presented dissertation addresses the molecular and cellular mechanisms of cocaine addiction. Our team previously showed the development of addiction-like behaviour in mice depends on co-activation of glutamate NMDA receptors (NMDAR) and dopamine-1 receptors (D1R), and the ERK signalling pathway. My hypothesis was that the physical interaction between the D1R and NMDAR would be critical in cocaine-induced adaptations. This hypothesis was supported, as co-stimulation of the D1R and NMDAR favoured their physical interactions in cultured neurons. After I developed a peptide (TAT-GluN1C1) that specifically obstructs the association of the receptors, I found treating neurons with TAT-GluN1C1 inhibited the activation of the ERK pathway specifically downstream of co-stimulation of the D1R and NMDAR, but not when either receptor was individually stimulated. Furthermore, this physical interaction has functional consequences, as dissociation of the receptors prevented the D1R from potentiating NMDAR mediated synaptic transmission in brain slices. In vivo, the peptide prevented locomotor sensitisation, the progressive and long-lasting augmentation of cocaine’s stimulant effects observable as increased motor activity, in mice. Altogether, these results demonstrate for the first time a novel role for D1R/NMDAR physical interactions in cocaine-induced signalling, plasticity and long term behavioural adaptations that may also be necessary for the persistence of other drug-associated behaviours
Casassus, Guillaume. "La transmission glutamatergique cortico-accumbens : régulation et plasticité pré-synaptique." Bordeaux 2, 2004. http://www.theses.fr/2004BOR21131.
The nucleus accumbens forms the ventral part of the striatum. It has been proposed to serve as an interface between the limbic system and the motor system. Medium spiny neurons of the nucleus accumbens, that depend on excitatory afferents to generate action potentials, receive a dense glutamatergic innervation from the prefrontal cortex and form various limbic structures, including the hippocampal formation, the basolateral amygdala and the thalamus. Despite growing evidence that the nucleus accumbens is involved in important brain functions such as motivation, attention or reward, physiological regulation of the glutamatergic input in medium spiny neurons is still largely unknown. The efficacy of excitatory glutamatergic synaptic transmission is highly dependent on the activation of presynaptic autoreceptors and on the temporal pattern of activity of afferents. Using patch-clamp whole-cell recordings in acute slices of the mouse nucleus accumbens, we have highlighted new forms of synaptic modulation of the cortico-accumbens pathway : (1) functional presynaptic kainate receptors on cortical afferrents fibers inhibited glutamatergic synaptic transmission, (2) increase in tonic frequency stimulation of the cortical input to the nucleus accumbens induced a presynaptic facilitation or depression of the synaptic transmission depending on the initial release probability, (3) burst stimulation of cortical afferent fibers lead to a cumulative increase of the glutamatergic synaptic input through presynaptic increase in axonal reliability of action potentials propagation, and (4) sustained stimulation (14 Hz, 2 min) of cortical afferent fibers, induced long-term potentiation of glutamatergic synaptic transmission through presynaptic mechanisms and activation of ionotropic glutamate receptors. These results demonstrtate new original phenomenons that modulate cortico-accumbens glutamatergic synaptic strength in nucleus accumbens efferent neurons
Levenes, Carole. "Modulation pré et post-synaptique de la transmission et de la plasticité synaptique aux synapses entre fibres parallèles et cellules de Purkinje dans le cervelet de rongeur." Paris 11, 2000. http://www.theses.fr/2000PA112392.
Résumé anglais (idem)
Mitri, Christian. "Divergence évolutive chez les insectes : un nouveau groupe de récepteur, les mXRs, homologues aux récepteurs métabotropiques du glutamate : approche biochimique, pharmacologique et fonctionnelle." Montpellier 2, 2005. http://www.theses.fr/2005MON20055.
Rival, Thomas. "Mise en évidence du rôle des transporteurs du glutamate dans la physiologie synaptique et la prévention des neurodégénérescences chez la Drosophile." Aix-Marseille 2, 2005. http://www.theses.fr/2005AIX22043.
In Drosophila, glutamate is the neurotransmitter at neuromuscular junctions (NMJ) and in the central nervous system (CNS). We studied Drosophila homologues of genes coding for re-uptake glutamate transporters (EAAT) and vesicular glutamate transporters (VGLUT). DEAAT1, the only EAAT Drosophila glutamate transporter, is expressed in glial extensions that project in the neuropil. Inactivation of dEAAT1 by RNA interference led to increased duration of muscle potential, behavior deficits, shortened life span, increased sensitivity to oxidative stress and neuropil degeneration. These results demonstrate that dEAAT1 participates to the removal of glutamate at synapses, and prevent glutamate-induced neurotoxicity. We isolated DVGLUT a VGLUT gene. DVGLUT represented the first available marker of central glutamatergic synapses. Surprisingly, DVGLUT positive glutamatergic synapses were found in high abundance in the CNS. This suggests that glutamate is a major neurotransmitter in the Drosophila
Tardin, Catherine. "Détection de nano-objets individuels dans des cellules : étude de la structure dynamique de la synapse de neurones vivants et développement de l'imagerie par contraste interférentiel photothermique." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12848.
Lecointre, Maryline. "Evolution des transmissions glutamatergiques dans le cortex au cours du développement chez la souris : impact d'un anesthésique, la kétamine, sur le développement du R-NMDA." Rouen, 2014. http://www.theses.fr/2014ROUES044.
Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS). Glutamatergic transmission plays an important role in CNS development, including migration, differentiation and synaptic plasticity. Physiological activation of N-Methyl-D-Aspartate receptor (NMDA-R) is particularly involved in the developmental effects of glutamate. Therefore, a blocking or excessive activation of NMDA-R affects the cerebral development and particularly leads to cell death in neonate cortex. NMDA-R is a heterotetrameric ionotropic receptor, permeable to cations, widely expressed in the CNS and composed of different subunits (GluN1, GluN2A-D, GluN3A-B). In the cortex, it is composed of two obligatory GluN1 subunits which link the co-agonist, glycine or D -serine, mainly associated with GluN2A and/or GluN2B subunits which bind glutamate. GluN2 subunit composition of NMDA-R gives distinct pharmacological and electrophysiological properties. Moreover, GluN2A-containing NMDA-R are involved in cell survival and those containing GluN2B are involved in cell death. PDZ proteins, member of membrane-associated guanylate kinase family (MAGUK), including PSD95 (postsynaptic density 95) and SAP102 (synapse associated protein 102) interact with NMDA-R and play an important role in their membrane stabilization. Recently, it has been shown that GluN2A/PSD95 association played a role in synaptic maturation. Pharmacological agents used for anesthesia, such as ketamine, act as NMDA-R antagonists. This anesthetic with many clinical advantages (low impact on respiratory and cardiac functions) is used in pediatrics in order to sedate during short duration medical procedures. However, several experimental studies discussed the safety of the use of ketamine. Indeed, ketamine administration causes an increase in apoptotic cell death in the cerebral cortex of newborn mice. Moreover, a recent laboratory study showed, ex vivo, in the cortex of mice aged 2 days, that ketamine induced different effects on cell survival depending on cortical layers considered. In a first study, we conducted a comparative study of the effects of ketamine administration in vivo, in newborn mice (40 mg / kg sc), depending on the age at which this anesthetic was injected (postnatal days 2, 5 or 10). In the short term, we measured the ketamine effect on the cortical NMDA-R postnatal development and its association with MAGUK. In the long term, we evaluated the impact of ketamine administered at different postnatal ages, on motor activity measured in adulthood in two different contexts. Twenty-four hours after ketamine injection, GluN2B and GluN2A protein expression was decreased when the treatment was carried out at P5 and P10 respectively. After immunoprecipitation of scaffolding PSD95 protein, western blot revelation indicated that regardless of the age treatment, ketamine caused a reduction of the association of GluN2A subunit to PSD95, while the complex GluN2B/PSD95 was increased only when the treatment was performed at P5. At this stage, the disruption of GluN2A and GluN2B subunits expression was associated with a decrease in ERK1/2 phosphorylation and an increase in nNOS association with GluN2B/PSD95 protein complex. All these results therefore indicate that ketamine alter the developmental profile of NMDA-R subunits, suggesting a delay in synaptic maturation. In addition, at P5, ketamine treatment has functional impacts on intracellular signaling cascades. Laser microdissection on control mice cortex revealed a heterogeneous distribution of NMDA-R subunits between immature superficial cortical layers (I-IV ) and the mature deep cortical layers (V-VI). Ketamine disrupted this profile by decreasing GluN2A subunit expression in the superficial layers in P5-treated mice and increasing GluN1, GluN2A and GluN2B subunits in the deep layers when the treatment was performed at P10. In the long term, ketamine administration at P2 or P10 caused hyperlocomotion in an open field in adult males, with no effect in adult females. The measurement of voluntary motor activity during 72 h in a running-wheel placed in a life cage, revealed alterations in adulthood induced by ketamine administered in the perinatal period, dependent on age and sex. In conclusion of this first part of the thesis, a single injection of ketamine, whatever the age of treatment in the perinatal period, resulted in changes in the NMDA-R developmental profile in the short-term and alterations in motor activity persisting in adulthood. Despite the progress of obstetrics and neonatal reanimation, brain injury in newborns remain frequent (2 to 2. 5 children per 1000 births). They form the first cause of death or disability acquired in the perinatal period. Many risk factors are identified, such as prematurity, hypoxo-ischemic injuries, fetal-placental infections, hormonal deficiencies and toxic factors (alcohol, drugs). Excessive activation of glutamatergic transmission is frequently the cause of perinatally acquired lesions. Excess of glutamate leads to overactivation of its receptors including NMDA-R, leading to cell death by apoptosis and/or necrosis. The proximity of brain microvessels with neural cells and the presence of functional NMDA-R on brain microvascular endothelial cells (BMEC) suggest a particular influence of BMEC on cortical neurons during excitotoxic stress. Synaptic glutamate concentrations are regulated by ATP-dependent transporters, present in the membrane of glial cells and neurons. Five transporters subtypes are known (excitatory amino acid transporters; EAAT): EAAT1 and -2 are primarily expressed by astrocytes and EAAT3 and -4 are preferentialy expressed by neurons. Recently, it has been shown that EAAT1, -2 and -3 were also expressed by adult vascular endothelial cells, suggesting a role of endothelium in the control of extracellular glutamate concentrations. However, a recent laboratory study showed differences in glutamate sensibility between neonatal and adult murine BMEC. In a second study, we studied the expression of EAAT1, -2 and -3 in cortical microvessels of newborn and adult mice, as well as efficiency of glutamate uptake by BMEC. We showed that EAAT1, -2 and -3 expression in brain endothelium was greater in adults than in neonates, as well as the efficiency of glutamate uptake by BEMC. In conclusion of this second part of the thesis, this study indicates that there is a regulation of extracellular glutamate by endothelial cells and this control depends on the age. Low expression of EAAT in immature vascular endothelium could contribute to a particular sensitivity of newborn brain during excitotoxic stress in mice. In conclusion, this thesis contributed to characterize the specificity of glutamatergic transmission in the immature brain. Our results play in favor of special consideration of molecules interacting with glutamatergic transmission such as anesthetics in the perinatal period
Andrianarivelo, Andry. "Rôle des hétéromères formés par les récepteurs de la dopamine et du glutamate dans les adaptations à long terme induites par la cocaïne Unraveling the Functions of Endogenous Receptor Oligomers in the Brain Using Interfering Peptide: The Example of D1R/NMDAR Heteromers Modulation and functions of dopamine receptor heteromers in drugs of abuse-induced adaptations." Thesis, Sorbonne université, 2020. http://www.theses.fr/2020SORUS014.
Addictive substances hijack reward-dependent learning by increasing dopamine (DA) in the mesolimbic system, in particular in the striatum, where it modulates durably excitatory glutamatergic transmission and contributes to the establishment of persistent behavioral alterations. The integration of dopaminergic and glutamatergic signals within the striatum is achieved by the medium-size spiny neurons of the striatum (MSN), which form two mostly segregated populations: the MSN of the "direct pathway" expressing DA D1 receptors (D1R-MSN) and those of the "indirect pathway" which express the DA D2 receptors (D2R-MSN). A prevailing hypothesis is that the surge of DA evoked by drugs of abuse facilitates D1R-MSN activation through the stimulation of D1R, which promotes reinforcement, whereas the D2R-mediated inhibition of D2R-MSN prevent their so-called anti-reward action. Our laboratory has previously shown that the physical interaction (i.e. heteromerization) between D1R and the NMDA glutamate receptor (NMDAR) was necessary for the facilitation of glutamatergic transmission by DA in D1R-MSN. Conversely, others have shown that the D2R/NMDAR interaction underlies the inhibitory effect of DA on NMDAR signaling in D2R-MSN.However, the modulation and function of these heteromers in vivo in responses to cocaine are still unknown. Using the “proximity ligation assay” technique, we found that locomotor sensitization induced by repeated exposure to cocaine is associated with the formation of D1R/NMDAR heteromers in the Nucleus Accumbens (NAc) and the Dorsal Striatum, while the D2R/GluN2B heteromerization is mainly observed within the NAc. To identify the roles of the DAR/NMDAR heteromers in the different phases of the molecular, morphological and behavioral adaptations induced by cocaine in vivo, we designed a viral-based approach to disrupt the DAR/NMDAR heteromers in a controlled manner over time owing to a doxycycline-dependent promoter. We found that the disruption of the D1R/NMDAR interaction in the NAc blocks cocaine-evoked long-term synaptic plasticity in D1R-MSN and the development of both psychomotor sensitization and conditioned place preference (CPP). By contrast, blocking the D2R/NMDAR interaction interferes with the maintenance of cocaine psychomotor sensitization and CPP. The observation of a preferential involvement of the D2R/GluN2B heteromers in the maintenance of behavioral responses to cocaine and their lack of effect in natural reward suggests that this subtype of heteromers could be a promising therapeutic target. Based on this hypothesis, we developed the detection of D2R/NMDAR complexes from human post-mortem striatal tissues prepared from individuals with a history of psychostimulants dependence or healthy subjects. This allowed us to show that, despite a sharp decrease in D2R expression, the proportion of D2R forming heteromers with NMDAR is three-fold higher in addict subjects compared to healthy controls. This work therefore reinforces the evidence of the central role of interactions between the dopaminergic and glutamatergic systems in drug responses and identifies the DAR/NMDAR heteromers as molecular targets with therapeutic potential not only in addiction but also for the numerous psychiatric disorders associated with an imbalance between dopaminergic and glutamatergic transmissions
Gouix, Elsa. "Conséquences d'un dysfonctionnement astrocytaire sur la viabilité neuronale dans des modèles d'hypoxie/ischemie." Aix-Marseille 2, 2009. http://theses.univ-amu.fr.lama.univ-amu.fr/2009AIX22091.pdf.
Astrocytes have a crucial function in modulating neuronal activity especially in glutamatergic synapse where they tightly control transmission through sodium and secondarily ATP dependent-high affinity glutamate transporters. In hypoxic/ischemic (HI) conditions a major energetic crisis takes place and glutamate uptake has been shown to be stopped and aven reversed leading to extracellular glutamate concentration increase. My thesis results show that reverse glial glutamate uptake pharmacologically induced by PDC triggers neuronal death through extrasynaptic NMDA receptor induced calcium entry, neuronal mitochondrial membrane potential impairment and a shut off of the neurotrophic ERK 1/2 signaling pathway. This neuronal death wa rapid and necrotic. Using an oxygen and glucose deprivation model (OGD, HI model in vitro) we evidenced the oxidative and apoptotic death of differentiated (quiescent) murine striatal astrocytes 3 days after 3h-OGD. This death war correlated with a decreased capacity to synthetise glutathione the main antioxidant of the mamml CNS. By the same time, undifferentiated striatal astrocytes were resistant to 3h-OGD but changed transiently their morphology to Alzheimer type II astrocytes, a phenotype commonly observed in perinatal ischemic humain brain. Viability of striatal naïve neurons in coculture with differentiated astrocytes seemed to be higher than in coculture with undifferentiated ones. This could be explained by glutathione release from apoptotic astrocytes during the coculture, which can be neuroprotective. On the other hand a presumed glutamate release from undifferentiated astrocytes may activate extrasynaptic NMDA receptors and tigger neuronal death. These data illustrate that astrocytes may display different responses to HI insult thus conditioning neuronal
Cao, Anne-Marinette Hanh. "Etudes de la dynamique structurale des récepteurs métabotropiques du glutamate par fluorescence en molécule unique." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT050.
Metabotropic glutamate receptors (mGluR), which belong to class C of G protein-coupled receptors (GPCR), are well-known for their important roles in neurological and psychiatric disorders. Understanding of receptor activation is essential to decipher the receptor functioning, and thus orientate drugs design for targeted therapeutics. Recently, the number of GPCR crystal structures has increased exponentially thanks to the application of protein stabilization methods. However, these crystallography studies have revealed certain ambiguities and discrepancies, and these approaches do not take into account the dynamic nature of GPCR activation. Indeed, single-molecule studies, including single-molecule FRET (smFRET), have revealed the highly dynamic nature of GPCR in general, and fast conformational changes of mGluR domains in particular. Here, we study the activation mechanism of the full-length mGluR by FRET techniques at ensemble and single-molecule level. Homogenous time-resolved fluorescence (HTRF) was applied for optimizing the sample preparation. An appropriate protocol was established, allowing to extract mGlu2 full-length in detergent from the HEK293T cells without significantly affecting its pharmacology and stability. smFRET experiments were performed using the combination of multiparameter fluorescence detection (MFD) with pulsed interleaved excitation (PIE). Advanced data analysis such as ratiometric FRET efficiency, lifetime-based FRET measurement, and fluorescence correlation spectroscopy (FCS) revealed that the fast dynamic oscillation in sub-millisecond timescale of the full-length mGlu2, and prove the stabilization role of the transmembrane domain of the full-length receptor in favor of the active state
Moutin, Enora. "Organisation et dynamique des protéines d'échafaudage de la postsynapse glutamatergique : implications dans la physio-pathologie de la transmission synaptique." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20238/document.
The glutamatergic synapse is composed by an axonal presynapse and a postsynapse which is supported by a dendritic spine. The spine contains membrane glutamatergic receptors connected to sub-membrane scaffolding proteins. These postsynaptic density (PSD) proteins allow to link receptors to their signaling pathways. NMDA receptors are associated to metabotropic glutamate receptors (mGluR1/5) through the PSD95/GKAP/Shank/Homer protein complex. During my PhD, I have characterized protein-protein interactions dynamic in this complex and studied functional consequences on receptor activity.Homer is a multimeric protein linking mGluR5 to the PSD95/GKAP/Shank complex. The monomeric form Homer1a is unable to connect mGluR5 to Shank. We have shown that complex disruption by Homer1a expression induces a direct interaction between NMDA and mGluR5 and subsequent inhibition of NMDA currents. We have shown that this process occurs during synaptic potentiation.I have also studied the interaction between GKAP and DLC2, a light chain shared by molecular transporters. I have characterized the occurrence and dynamic of GKAP-DLC2 interaction and shown that neuronal activity increases this interaction leading to synaptic accumulation of GKAP. Moreover, this interaction allows PSD95 targeting into dendritic spines and NMDA currents increase. Together, these results show that scaffolding proteins participate to receptor signaling, modulate synaptic transmission and underlie long-term synaptic plasticity mechanisms