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Ishan Gupta, Andrew M J Young
The non-competitive glutamate antagonist, phencyclidine is used in rodents to model behavioural deficits see in schizophrenia. Importantly, these deficits endure long after the cessation of short-term chronic treatment (sub-chronic), indicating that the drug treatment causes long-term changes in the physiology and/or chemistry of the brain. There is evidence that this may occur through glutamatergic modulation of mesolimbic dopamine release, perhaps involving metabotropic glutamate receptors (mGluR). This study sought to investigate the effect of sub-chronic phencyclidine pretreatment on modulation of dopamine neurotransmission by metabotropic glutamate receptors 2 and 5 (mGluR2 and mGluR5) in the nucleus accumbens shell in vitro, with the hypothesis that phencyclidine pretreatment would disrupt the mGluR-mediated modulation of dopamine release...
March 7, 2018: Brain Research
Bart de Laat, Akila Weerasekera, Gil Leurquin-Sterk, Guy M Bormans, Uwe Himmelreich, Cindy Casteels, Koen Van Laere
Cocaine addiction is a disorder without diagnostic biomarkers or effective pharmacotherapy. Research on the glutamatergic system lacks longitudinal data starting before exposure to cocaine. We present findings in a rat model of cocaine self-administration that was followed-up longitudinally using the mGluR5 tracer18 F-FPEB PET, 1H-MRS and behavioral tests. Methods: Forty-two Wistar rats were scanned with18 F-FPEB PET and 1H-MRS before and after sucrose or IV cocaine self-administration, during withdrawal and relapse...
March 1, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Xia Li, Xiao-Qing Peng, Chloe J Jordan, Jie Li, Guo-Hua Bi, Yi He, Hong-Ju Yang, Hai-Ying Zhang, Eliot L Gardner, Zheng-Xiong Xi
Metabotropic glutamate receptor 5 (mGluR5) antagonism inhibits cocaine self-administration and reinstatement of drug-seeking behavior. However, the cellular and molecular mechanisms underlying this action are poorly understood. Here we report a presynaptic glutamate/cannabinoid mechanism that may underlie this action. Systemic or intra-nucleus accumbens (NAc) administration of the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) dose-dependently reduced cocaine (and sucrose) self-administration and cocaine-induced reinstatement of drug-seeking behavior...
February 27, 2018: Scientific Reports
Jeremy S Lum, Samuel J Millard, Xu-Feng Huang, Lezanne Ooi, Kelly A Newell
BACKGROUND: The nucleus accumbens (NAcc) has been implicated in the pathology and treatment of schizophrenia. Recent postmortem evidence suggests a hyperglutamatergic state in the NAcc. With the present study we aimed to explore possible glutamatergic alterations in the NAcc of a large schizophrenia cohort. METHODS: We performed immunoblots on postmortem NAcc samples from 30 individuals who had schizophrenia and 30 matched controls. We examined the protein expression of primary glutamatergic receptors, including the N -methyl-D-aspartate (NMDA) receptor (NR1, NR2A and NR2B subunits) and the group 1 metabotropic glutamate receptor (mGluR1 and mGluR5; dimeric and monomeric forms)...
March 2018: Journal of Psychiatry & Neuroscience: JPN
Dasiel O Borroto-Escuela, Sonja Hinz, Gemma Navarro, Rafael Franco, Christa E Müller, Kjell Fuxe
Adenosine is a nucleoside mainly formed by degradation of ATP, located intracellularly or extracellularly, and acts as a neuromodulator. It operates as a volume transmission signal through diffusion and flow in the extracellular space to modulate the activity of both glial cells and neurons. The effects of adenosine are mediated via four adenosine receptor subtypes: A1R, A2AR, A2BR, A3R. The A2AR has a wide-spread distribution but it is especially enriched in the ventral and dorsal striatum where it is mainly located in the striato-pallidal GABA neurons at a synaptic and extrasynaptic location...
2018: Frontiers in Neuroscience
Kenneth J O'Riordan, Neng-Wei Hu, Michael J Rowan
Promotion of long-term depression (LTD) mechanisms by synaptotoxic soluble oligomers of amyloid-β (Aß) has been proposed to underlie synaptic dysfunction in Alzheimer's disease (AD). Previously, LTD was induced by relatively non-specific electrical stimulation. Exploiting optogenetics, we studied LTD using a more physiologically diffuse spatial pattern of selective pathway activation in the rat hippocampus in vivo. This relatively sparse synaptic LTD requires both the ion channel function and GluN2B subunit of the NMDA receptor but, in contrast to electrically induced LTD, is not facilitated by boosting endogenous muscarinic acetylcholine or metabotropic glutamate 5 receptor activation...
February 20, 2018: Cell Reports
S Hossein Fatemi, Dean F Wong, James R Brašić, Hiroto Kuwabara, Anil Mathur, Timothy D Folsom, Suma Jacob, George M Realmuto, José V Pardo, Susanne Lee
Background: Autism is a neurodevelopmental disorder that is first manifested during early childhood. Postmortem experiments have identified significantly elevated expression of metabotropic glutamate receptor 5 (mGluR5) in cerebellar vermis and prefrontal cortex of individuals with autism. Methods: In the current study we employed the mGluR5 tracer [18 F]-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ([18 F]-FPEB) to quantify mGluR5 binding in vivo in adults with autism vs...
2018: Cerebellum & Ataxias
Pauli M Turunen, Lauri M Louhivuori, Verna Louhivuori, Jyrki P Kukkonen, Karl E Åkerman
Cell-cell communication plays a central role in the guidance of migrating neuronal precursor cells during the development of the cerebral cortex. Endocannabinoids (eCBs) have previously been shown to be one of the central factors regulating neuronal migration. In this study the effects of eCBs on different parameters, expected to affect embryonic cortical neuronal motility have been analyzed in neurosphere derived neuroblasts using time-lapse microscopy. Increased endogenous production of the endocannabinoid 2-arachidonyl glycerol (2-AG) causes bursts of neuroblast motility...
February 10, 2018: Neuroscience
Minkyung Lee, Hae-June Lee, In Suh Park, Ji-Ae Park, Yeon Ju Kwon, Young Hoon Ryu, Chul Hoon Kim, Joo Hyun Kang, In Young Hyun, Kyo Chul Lee, Jae Yong Choi
The aim of the present study was to evaluate functional changes of mGluR5 expression in advanced Alzheimer's disease (AD) using positron emission tomography (PET) with an mGluR5 specific radiotracer ([18F]FPEB) in 5xFAD AD model mice. Subsequently, in the same animal, mGluR5 expression was quantified by immunoassay techniques. The non-displaceable binding potential values for mGluR5 was estimated by the Logan's graphical analysis. Brain PET imaging revealed that radioactivities in the hippocampus and the striatum were significantly lower in 5xFAD rats compared to control animals...
February 7, 2018: Neuropharmacology
A Harrison Brody, Stephen M Strittmatter
Alzheimer's disease (AD) represents an impending global health crisis, yet the complexity of AD pathophysiology has so far precluded the development of any interventions to successfully slow or halt AD progression. It is clear that accumulation of Amyloid-beta (Aβ) peptide triggers progressive synapse loss to cause AD symptoms. Once initiated by Aβ, disease progression is complicated and accelerated by inflammation and by tau pathology. The recognition that Aβ peptide assumes multiple distinct states and that soluble oligomeric species (Aβo) are critical for synaptic damage is central to molecular understanding of AD...
2018: Advances in Pharmacology
Alessandro Piva, Elisabetta Gerace, Marzia Di Chio, Lisa Osanni, Laura Padovani, Lucia Caffino, Fabio Fumagalli, Domenico E Pellegrini-Giampietro, Cristiano Chiamulera
Metaplasticity, defined as the plasticity of synaptic plasticity, could affect learning and memory at different neural levels. It was hypothesized that metaplasticity changes on glutamate receptors may affect memory destabilization, promoting or preventing reconsolidation. We investigated the metaplastic effect of NMDA channel blocker MK-801 on sucrose instrumental memory reconsolidation in a behavioural rat model associated to the assessment of molecular markers of metaplasticity, memory retrieval, destabilization and reconsolidation...
January 31, 2018: Neurobiology of Learning and Memory
Manuela Mellone, Fabrizio Gardoni
Overactivation of the glutamatergic synapse leading to maladaptive synaptic plasticity in the basal ganglia is a well-demonstrated process involved in the onset of L-DOPA-induced dyskinesia (LID). Changes in glutamate release are paralleled by compensatory modifications of the expression and/or synaptic localization of both ionotropic and metabotropic glutamate receptors (mGluRs). Accordingly, compounds targeting N-methyl-D-aspartate glutamate receptors (NMDARs) and specific subtypes of metabotropic glutamate receptors (mGluR4 and mGluR5) have been tested both in preclinical and clinical studies...
January 31, 2018: Journal of Neural Transmission
Yuan Zhao, Qian Li, Xue-Yan Li, Peng Cui, Feng Gao, Ke Zhu, Ling-Zhu Li, Xing-Huai Sun, Zhongfeng Wang
EphB/ephrinB reverse signaling is involved in retinal ganglion cell (RGC) apoptosis in experimental glaucoma. Here, we further investigated the mechanisms underlying EphB/ephrinB reverse signaling activation induced RGC apoptosis in a rat chronic ocular hypertension (COH) model, using patch-clamp techniques in retinal slices. In COH retinas, RGCs showed higher spontaneous firing frequency and much more depolarized membrane potential as compared to control, which was mimicked by intravitreally injection of EphB2-Fc, an activator of ephrinB2...
January 20, 2018: Brain Research
Andrea Ferrigno, Clarissa Berardo, Laura Giuseppina Di Pasqua, Veronica Siciliano, Plinio Richelmi, Ferdinando Nicoletti, Mariapia Vairetti
2-Methyl-6-(phenylethynyl)pyridine (MPEP), a negative allosteric modulator of the metabotropic glutamate receptor (mGluR) 5, protects hepatocytes from ischemic injury. In astrocytes and microglia, MPEP depletes ATP. These findings seem to be self-contradictory, since ATP depletion is a fundamental stressor in ischemia. This study attempted to reconstruct the mechanism of MPEP-mediated ATP depletion and the consequences of ATP depletion on protection against ischemic injury. We compared the effects of MPEP and other mGluR5 negative modulators on ATP concentration when measured in rat hepatocytes and acellular solutions...
January 23, 2018: International Journal of Molecular Sciences
Funda Akkus, Yoan Mihov, Valerie Treyer, Simon M Ametamey, Anass Johayem, Smeralda Senn, Susanne Rösner, Alfred Buck, Gregor Hasler
Glutamate signaling plays a major role in addiction. Preclinical research strongly suggests an implication of G-protein-coupled metabotropic glutamate receptor subtype 5 (mGluR5) in nicotine addiction and alcohol use disorder. In humans, smoking is related to a global reduction in mGluR5 availability. In the present study, we investigated mGluR5 in vivo in patients with alcohol use disorder without the confounding effects of smoking. A total of 14 male subjects with alcohol use disorder and at least a 25-day abstinence and 14 matched male non-smoking healthy controls were included in the study...
January 10, 2018: Translational Psychiatry
Sarah N Isherwood, Trevor W Robbins, Jeffrey W Dalley, Anton Pekcec
Dysregulation of prefrontal cortical glutamatergic signalling via NMDA receptor hypofunction has been implicated in cognitive dysfunction and impaired inhibitory control in such neuropsychiatric disorders as schizophrenia, attention deficit hyperactivity disorder and drug addiction. Although NMDA receptors functionally interact with metabotropic glutamate receptor 5 (mGluR5), the consequence of this interaction for glutamate release in the prefrontal cortex (PFC) is unknown. We therefore investigated the effects of positive and negative allosteric mGluR5 modulation on changes in extracellular glutamate efflux in the medial PFC (mPFC) induced by systemic administration of the non-competitive NMDA receptor antagonist dizocilpine (or MK801) in rats...
January 6, 2018: Journal of Neurochemistry
Iaroslav Savtchouk, Andrea Volterra
Astrocytes are highly complex cells with many emerging putative roles in brain function. Of these, gliotransmission (active information transfer from glia to neurons) has probably the widest implications on our understanding of how the brain works: do astrocytes really contribute to information processing within the neural circuitry? "Positive evidence" for this stems from work of multiple laboratories reporting many examples of modulatory chemical signaling from astrocytes to neurons in the timeframe of hundreds of milliseconds to several minutes...
January 3, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Khaled S Abd-Elrahman, Alison Hamilton, Shaunessy R Hutchinson, Fang Liu, Ryan C Russell, Stephen S G Ferguson
Huntington's disease (HD) is a neurodegenerative disease caused by an expansion in the huntingtin protein (also called Htt) that induces neuronal cell death with age. We found that the treatment of 12-month-old symptomatic heterozygous and homozygous zQ175 huntingtin knockin mice for 12 weeks with CTEP, a negative allosteric modulator of metabotropic glutamate receptor 5 (mGluR5), reduced the size and number of huntingtin aggregates, attenuated caspase-3 activity, and reduced both neuronal apoptosis and neuronal loss in brain tissue...
December 19, 2017: Science Signaling
Ashlie N Reker, Alfredo Oliveros, John M Sullivan, Lailun Nahar, David J Hinton, Taehyun Kim, Robert C Bruner, Doo-Sup Choi, Nicholas E Goeders, Hyung W Nam
Dysfunction of N-methyl-d-aspartate receptor (NMDAR) signaling in the nucleus accumbens (NAc) has been implicated in the pathophysiology of alcohol use disorders (AUD). Neurogranin (Ng), a calmodulin-binding protein, is exclusively expressed in the post-synapse, and mediates NMDAR driven synaptic plasticity by regulating the calcium-calmodulin (Ca2+ -CaM) pathway. To study the functional role of Ng in AUD, we administrated behavior tests including Pavlovian instrument transfer (PIT), operant conditioning, and rotarod test using Ng null mice (Ng-/- mice)...
March 15, 2018: Neuropharmacology
Elizabeth M Berry-Kravis, Lothar Lindemann, Aia E Jønch, George Apostol, Mark F Bear, Randall L Carpenter, Jacqueline N Crawley, Aurore Curie, Vincent Des Portes, Farah Hossain, Fabrizio Gasparini, Baltazar Gomez-Mancilla, David Hessl, Eva Loth, Sebastian H Scharf, Paul P Wang, Florian Von Raison, Randi Hagerman, Will Spooren, Sébastien Jacquemont
Neurodevelopmental disorders such as fragile X syndrome (FXS) result in lifelong cognitive and behavioural deficits and represent a major public health burden. FXS is the most frequent monogenic form of intellectual disability and autism, and the underlying pathophysiology linked to its causal gene, FMR1, has been the focus of intense research. Key alterations in synaptic function thought to underlie this neurodevelopmental disorder have been characterized and rescued in animal models of FXS using genetic and pharmacological approaches...
December 8, 2017: Nature Reviews. Drug Discovery
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