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Nardecchia F, Orlando R, Iacovelli L, Colamartino M, Fiori E, Leuzzi V, Piccinin S, Nistico R, Puglisi-Allegra S, Di Menna L, Battaglia G, Nicoletti F, Pascucci T. Targeting mGlu5 Metabotropic Glutamate Receptors in the Treatment of Cognitive Dysfunction in a Mouse Model of Phenylketonuria. Front Neurosci 2018; 12:154. [PMID: 29615849 PMCID: PMC5864888 DOI: 10.3389/fnins.2018.00154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 02/26/2018] [Indexed: 11/23/2022] Open
Abstract
We studied group-I metabotropic glutamate (mGlu) receptors in Pahenu2 (ENU2) mice, which mimic the genetics and neurobiology of human phenylketonuria (PKU), a metabolic disorder characterized, if untreated, by autism, and intellectual disability (ID). Male ENU2 mice showed increased mGlu5 receptor protein levels in the hippocampus and corpus striatum (but not in the prefrontal cortex) whereas the transcript of the mGlu5 receptor was unchanged. No changes in mGlu1 receptor mRNA and protein levels were found in any of the three brain regions of ENU2 mice. We extended the analysis to Homer proteins, which act as scaffolds by linking mGlu1 and mGlu5 receptors to effector proteins. Expression of the long isoforms of Homer was significantly reduced in the hippocampus of ENU2 mice, whereas levels of the short Homer isoform (Homer 1a) were unchanged. mGlu5 receptors were less associated to immunoprecipitated Homer in the hippocampus of ENU2 mice. The lack of mGlu5 receptor-mediated long-term depression (LTD) in wild-type mice (of BTBR strain) precluded the analysis of hippocampal synaptic plasticity in ENU2 mice. We therefore performed a behavioral analysis to examine whether pharmacological blockade of mGlu5 receptors could correct behavioral abnormalities in ENU2 mice. Using the same apparatus we sequentially assessed locomotor activity, object exploration, and spatial object recognition (spatial novelty test) after displacing some of the objects from their original position in the arena. Systemic treatment with the mGlu5 receptor antagonist, MPEP (20 mg/kg, i.p.), had a striking effect in the spatial novelty test by substantially increasing the time spent in exploring the displaced objects in ENU2 mice (but not in wild-type mice). These suggest a role for mGlu5 receptors in the pathophysiology of ID in PKU and suggest that, also in adult untreated animals, cognitive dysfunction may be improved by targeting these receptors with an appropriate therapy.
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Affiliation(s)
- Francesca Nardecchia
- Department of Physiology and Pharmacology, Sapienza Università di Roma, Rome, Italy.,Department of Pediatrics and Child Neuropsychiatry, Sapienza Università di Roma, Rome, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, Sapienza Università di Roma, Rome, Italy
| | - Luisa Iacovelli
- Department of Physiology and Pharmacology, Sapienza Università di Roma, Rome, Italy
| | - Marco Colamartino
- Daniel Bovet Department of Psychology, Neurobiology Research Center, Sapienza Università di Roma, Rome, Italy
| | - Elena Fiori
- Daniel Bovet Department of Psychology, Neurobiology Research Center, Sapienza Università di Roma, Rome, Italy
| | - Vincenzo Leuzzi
- Department of Pediatrics and Child Neuropsychiatry, Sapienza Università di Roma, Rome, Italy
| | - Sonia Piccinin
- Department of Physiology and Pharmacology, Sapienza Università di Roma, Rome, Italy.,Department of Biology, Università degli Studi di Roma Tor Vergata, Rome, Italy
| | - Robert Nistico
- Department of Biology, Università degli Studi di Roma Tor Vergata, Rome, Italy
| | - Stefano Puglisi-Allegra
- Daniel Bovet Department of Psychology, Neurobiology Research Center, Sapienza Università di Roma, Rome, Italy.,IRCCS Foundation Santa Lucia, Rome, Italy
| | | | | | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza Università di Roma, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
| | - Tiziana Pascucci
- Daniel Bovet Department of Psychology, Neurobiology Research Center, Sapienza Università di Roma, Rome, Italy.,IRCCS Foundation Santa Lucia, Rome, Italy
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Ferraguti F. Metabotropic glutamate receptors as targets for novel anxiolytics. Curr Opin Pharmacol 2018; 38:37-42. [PMID: 29494817 DOI: 10.1016/j.coph.2018.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/12/2018] [Indexed: 12/12/2022]
Abstract
Anxiety disorders are highly prevalent psychiatric illnesses posing an important social and economic burden. Their current pharmacotherapy shows short term efficacy, though nearly one third of patients do not achieve sustained remission. There is, therefore, a strong medical need for new therapeutic agents acting through novel mechanisms of action. Considerable work has focused on metabotropic glutamate (mGlu) receptors as potential targets for novel anxiolytics. Ligands acting at mGlu receptors showed promising results in preclinical studies, whereas their efficacy was dubious in clinical trials. Recent preclinical and clinical studies have opened new prospects for targeting mGlu receptors to treat anxiety disorders. This review provides an outlook on these progresses.
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Affiliation(s)
- Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1A, 6020 Innsbruck, Austria.
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López-Zapata A, León-Navarro DA, Crespo M, Albasanz JL, Martín M. Chronic oral administration of MPEP, an antagonist of mGlu5 receptor, during gestation and lactation alters mGlu5 and A2A receptors in maternal and neonatal brain. Neuroscience 2017; 344:187-203. [DOI: 10.1016/j.neuroscience.2016.12.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 12/06/2016] [Accepted: 12/12/2016] [Indexed: 12/29/2022]
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Peterlik D, Flor PJ, Uschold-Schmidt N. The Emerging Role of Metabotropic Glutamate Receptors in the Pathophysiology of Chronic Stress-Related Disorders. Curr Neuropharmacol 2016; 14:514-39. [PMID: 27296643 PMCID: PMC4983752 DOI: 10.2174/1570159x13666150515234920] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 04/04/2015] [Accepted: 05/12/2015] [Indexed: 12/28/2022] Open
Abstract
Chronic stress-related psychiatric conditions such as anxiety, depression, and alcohol abuse are an enormous public health concern. The etiology of these pathologies is complex, with psychosocial stressors being among the most frequently discussed risk factors. The brain glutamatergic neurotransmitter system has often been found involved in behaviors and pathophysiologies resulting from acute stress and fear. Despite this, relatively little is known about the role of glutamatergic system components in chronic psychosocial stress, neither in rodents nor in humans. Recently, drug discovery efforts at the metabotropic receptor subtypes of the glutamatergic system (mGlu1-8 receptors) led to the identification of pharmacological tools with emerging potential in psychiatric conditions. But again, the contribution of individual mGlu subtypes to the manifestation of physiological, molecular, and behavioral consequences of chronic psychosocial stress remains still largely unaddressed. The current review will describe animal models typically used to analyze acute and particularly chronic stress conditions, including models of psychosocial stress, and there we will discuss the emerging roles for mGlu receptor subtypes. Indeed, accumulating evidence indicates relevance and potential therapeutic usefulness of mGlu2/3 ligands and mGlu5 receptor antagonists in chronic stress-related disorders. In addition, a role for further mechanisms, e.g. mGlu7-selective compounds, is beginning to emerge. These mechanisms are important to be analyzed in chronic psychosocial stress paradigms, e.g. in the chronic subordinate colony housing (CSC) model. We summarize the early results and discuss necessary future investigations, especially for mGlu5 and mGlu7 receptor blockers, which might serve to suggest improved therapeutic strategies to treat stress-related disorders.
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Affiliation(s)
| | - Peter J Flor
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
| | - Nicole Uschold-Schmidt
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
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Isherwood SN, Pekcec A, Nicholson JR, Robbins TW, Dalley JW. Dissociable effects of mGluR5 allosteric modulation on distinct forms of impulsivity in rats: interaction with NMDA receptor antagonism. Psychopharmacology (Berl) 2015; 232:3327-44. [PMID: 26063678 DOI: 10.1007/s00213-015-3984-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/29/2015] [Indexed: 02/03/2023]
Abstract
RATIONALE Impaired N-methyl-D-aspartate (NMDA) receptor signalling underlies several psychiatric disorders that express high levels of impulsivity. Although synergistic interactions exist between NMDA receptors and metabotropic glutamate receptor 5 (mGluR5), the significance of this interaction for impulsivity is unknown. OBJECTIVE This study aims to investigate the effects of negative and positive allosteric mGluR5 modulation (NAM/PAM) on trait impulsivity and impulsivity evoked by NMDA receptor antagonism in rats. METHODS Motor and choice impulsivity were assessed using the five-choice serial reaction time task (5-CSRTT) and delayed-discounting task (DDT), respectively. The effects of RO4917523 and 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) (NAMs) and ADX47273 (PAM) were investigated in non-impulsive rats and in trait high- and low-impulsive rats. The effects of these compounds on impulsivity induced by NMDA receptor antagonism (MK801) in the 5-CSRTT were also investigated. RESULTS RO4917523 (0.1-1 mg/kg) decreased premature responding and increased omissions but had no effect on locomotor activity up to 0.1 mg/kg. MTEP significantly increased omissions, decreased accuracy and slowed responding but had no effect on premature responding. ADX47273 decreased premature responding at doses that had no effect on locomotor activity. MK801 increased premature responding and impaired attentional accuracy; these deficits were dose dependently rescued by ADX47273 pre-treatment. Allosteric modulation of mGluR5 had no significant effect on choice impulsivity, nor did it modulate general task performance. CONCLUSIONS These findings demonstrate that mGluR5 allosteric modulation selectively dissociates motor and choice impulsivity. We further show that mGluR5 PAMs may have therapeutic utility in selectively targeting specific aspects of impulsivity and executive dysfunction.
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Affiliation(s)
- Sarah N Isherwood
- Boehringer Ingelheim Pharma GmbH & Co. KG, Div. Research Germany, Birkendorfer Strasse 65, 88397, Biberach an der Riss, Germany
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Silverman JL, Babineau BA, Oliver CF, Karras MN, Crawley JN. Influence of stimulant-induced hyperactivity on social approach in the BTBR mouse model of autism. Neuropharmacology 2013; 68:210-22. [PMID: 22968082 PMCID: PMC3522798 DOI: 10.1016/j.neuropharm.2012.07.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/09/2012] [Accepted: 07/24/2012] [Indexed: 12/12/2022]
Abstract
Translational research is needed to discover pharmacological targets and treatments for the diagnostic behavioral domains of autism spectrum disorders. Animal models with phenotypic relevance to diagnostic criteria offer clear experimental strategies to test the efficacy and safety of novel treatments. Antagonists of mGluR5 receptors are in clinical trials for Fragile X syndrome and under investigation for the treatment of autism spectrum disorders. However, in preclinical studies of mGluR5 compounds tested in our laboratory and others, increased locomotion following mGluR5 modulation has been observed. Understanding the influence of general activity on sociability and repetitive behaviors will increase the accuracy of interpretations of positive outcomes measured from pharmacological treatment that produces locomotor activating or sedating effects. In the present studies, dose-response curves for d-amphetamine (AMPH)-induced hyperlocomotion were similar in standard B6 mice and in the BTBR mouse model of autism. AMPH produced significant, robust reductions in the high level of repetitive self-grooming that characterizes BTBR, and also reduced the low baseline grooming in B6, indicating that AMPH-induced hyperlocomotion competes with time spent engaged in self-grooming. We then tested AMPH in B6 and BTBR on the 3-chambered social approach task. One component of sociability, the time spent in the chamber with the novel mouse, in B6 mice was reduced, while the sniffing time component of sociability in BTBR mice was enhanced. This finding replicated across multiple cohorts treated with AMPH and saline vehicle. In-depth analysis revealed that AMPH increased the number and decreased the duration of sniffing bouts in BTBR, suggesting BTBR treated with AMPH mostly engaged in brief sniffs rather than true social interactions with the novel mouse during the social approach task. Our data suggest that compounds with stimulant properties may have some direct benefits on reducing repetitive behaviors in autism spectrum disorders, particularly in the subset of autistic individuals with hyperactivity. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Jill L Silverman
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Bethesda, MD 20892-3730, USA.
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Varga B, Kassai F, Gyertyán I. Interactions of CB1 and mGlu5 receptor antagonists in food intake, anxiety and memory models in rats. Pharmacol Biochem Behav 2012; 103:425-30. [PMID: 23026059 DOI: 10.1016/j.pbb.2012.09.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 09/19/2012] [Accepted: 09/23/2012] [Indexed: 11/17/2022]
Abstract
CB(1) receptor antagonists proved to be effective anti-obesity drugs, however, their depressive and anxiogenic effects became also evident. Finding solution to overcome these psychiatric side effects is still in focus of research. Based on the available clinical and preclinical results we hypothesized that the combination of CB(1) and mGlu(5) receptor antagonisms may result in a pharmacological intervention, where the anxiolytic mGlu(5) receptor inhibition may counteract the anxiogenic psychiatric side effects of CB(1) antagonism, while CB(1) antagonism may ameliorate the memory impairing effect of mGlu(5) receptor antagonism. Further, the two components will synergistically interact in blocking food-intake and reducing obesity. For testing the interaction of mGlu(5) and CB(1) receptor antagonism MTEP [3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pridine; SIB-1757, 6-methyl-2-(phenylazo)-3-pyridinol)] (mGlu(5) antagonist) and rimonabant [(5-(4-Chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide)hydrochloride] (CB(1) antagonist) were used. All experiments were carried out in rats. Effects of the compounds on anxiety were tested in two foot shock induced ultrasonic vocalization paradigms, appetite suppression was assessed in the food intake test, while memory effects were tested in a context conditioned ultrasonic vocalization setup. MTEP abolished the anxiogenic effect of rimonabant, while there was an additive cooperation in suppressing appetite. However, rimonabant did not ameliorate the memory impairing effect of MTEP. By combination of CB(1) and mGluR5 antagonism, anxiety related side effects might be attenuated, appetite suppression maintained, nevertheless, the possible emergence of unwanted memory impairments can overshadow its therapeutic success.
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Affiliation(s)
- Balázs Varga
- Department of Behavioral Pharmacology, Gedeon Richter Plc., 1103 Budapest Gyömrői út 19-21, Hungary
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Salomons AR, Pinzon NE, Boleij H, Kirchhoff S, Arndt SS, Nordquist RE, Lindemann L, Jaeschke G, Spooren W, Ohl F. Differential effects of diazepam and MPEP on habituation and neuro-behavioural processes in inbred mice. Behav Brain Funct 2012; 8:30. [PMID: 22686184 PMCID: PMC3464737 DOI: 10.1186/1744-9081-8-30] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 06/11/2012] [Indexed: 12/04/2022] Open
Abstract
Background Previous studies have demonstrated a profound lack of habituation in 129P3 mice compared to the habituating, but initially more anxious, BALB/c mice. The present study investigated whether this non-adaptive phenotype of 129P3 mice is primarily based on anxiety-related characteristics. Methods To test this hypothesis and extend our knowledge on the behavioural profile of 129P3 mice, the effects of the anxiolyticdiazepam (1, 3 and 5 mg/kg) and the putative anxiolytic metabotropic glutamate receptor 5 (mGlu5R) antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP, 3, 10 and 30 mg/kg) treatment on within-trial (intrasession) habituation, object recognition (diazepam: 1 mg/kg; MPEP 10 mg/kg) and on the central-nervous expression of the immediate early gene c-Fos (diazepam: 1 mg/kg; MPEP 10 mg/kg) were investigated. Results Behavioural findings validated the initially high, but habituating phenotype of BALB/c mice, while 129P3 mice were characterized by impaired intrasession habituation. Diazepam had an anxiolytic effect in BALB/c mice, while in higher doses caused behavioural inactivity in 129P3 mice. MPEP revealed almost no anxiolytic effects on behaviour in both strains, but reduced stress-induced corticosterone responses only in 129P3 mice. These results were complemented by reduced expression of c-Fos after MPEP treatment in brain areas related to emotional processes, and increased c-Fos expression in higher integrating brain areas such as the prelimbic cortex compared to vehicle-treated 129P3 mice. Conclusions These results suggest that the strain differences observed in (non)adaptive anxiety behaviour are at least in part mediated by differences in gamma-aminobutyric acid- A and mGluR5 mediated transmission.
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Affiliation(s)
- Amber R Salomons
- Department of Animals in Science and Society, Division of Animal Welfare and Laboratory Animal Science, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 Utrecht, CM, The Netherlands.
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Harvey BH, Shahid M. Metabotropic and ionotropic glutamate receptors as neurobiological targets in anxiety and stress-related disorders: Focus on pharmacology and preclinical translational models. Pharmacol Biochem Behav 2012; 100:775-800. [DOI: 10.1016/j.pbb.2011.06.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/24/2011] [Accepted: 06/09/2011] [Indexed: 11/29/2022]
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Vinkers CH, Hendriksen H, van Oorschot R, Cook JM, Rallipalli S, Huang S, Millan MJ, Olivier B, Groenink L. Lifelong CRF overproduction is associated with altered gene expression and sensitivity of discrete GABA(A) and mGlu receptor subtypes. Psychopharmacology (Berl) 2012; 219:897-908. [PMID: 21833506 PMCID: PMC3259347 DOI: 10.1007/s00213-011-2423-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Accepted: 07/15/2011] [Indexed: 12/22/2022]
Abstract
RATIONALE Repeated activation of corticotropin-releasing factor (CRF) receptors is associated with increased anxiety and enhanced stress responsivity, which may be mediated via limbic GABAergic and glutamatergic transmission. OBJECTIVE The present study investigated molecular and functional alterations in GABA(A) receptor (GABA(A)R) and metabotropic glutamate receptor (mGluR) responsivity in transgenic mice that chronically overexpress CRF. METHODS CRF(1) receptor, GABA(A)R, and mGluR sensitivity were determined in CRF-overexpressing mice using the stress-induced hyperthermia (SIH) test. In addition, we measured mRNA expression levels of GABA(A)R α subunits and mGluRs in the amygdala and hypothalamus. RESULTS CRF-overexpressing mice were less sensitive to the anxiolytic effects of the CRF(1) receptor antagonists CP154,526 and DMP695, the GABA(A)R α(3)-selective agonist TP003 (0-3 mg/kg) and the mGluR(2/3) agonist LY379268 (0-10 mg/kg) in the SIH test. The hypothermic effect of the non-selective GABA(A)R agonist diazepam (0-4 mg/kg) and the α(1)-subunit-selective GABA(A)R agonist zolpidem (0-10 mg/kg) was reduced in CRF-overexpressing mice. No genotype differences were found using the GABA(A)R α(5)-subunit preferential compound SH-053-2'F-R-CH(3) and mGluR(5) antagonists MPEP and MTEP. CRF-overexpressing mice showed decreased expression levels of GABA(A)R α(2) subunit and mGluR(3) mRNA levels in the amygdala, whereas these expression levels were increased in the hypothalamus. CRF-overexpressing mice also showed increased hypothalamic mRNA levels of α(1) and α(5) GABA(A)R subunits. CONCLUSIONS We found that lifelong CRF overproduction is associated with altered gene expression and reduced functional sensitivity of discrete GABA(A) and mGluR receptor subtypes. These findings suggest that sustained over-activation of cerebral CRF receptors may contribute to the development of altered stress-related behavior via modulation of GABAergic and glutamatergic transmission.
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Affiliation(s)
- Christiaan H Vinkers
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus Institute of Neuroscience, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands.
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Parmentier-Batteur S, O'Brien JA, Doran S, Nguyen SJ, Flick RB, Uslaner JM, Chen H, Finger EN, Williams TM, Jacobson MA, Hutson PH. Differential effects of the mGluR5 positive allosteric modulator CDPPB in the cortex and striatum following repeated administration. Neuropharmacology 2010; 62:1453-60. [PMID: 21112344 DOI: 10.1016/j.neuropharm.2010.11.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 11/11/2010] [Accepted: 11/15/2010] [Indexed: 11/30/2022]
Abstract
The glutamatergic hypofunction hypothesis of schizophrenia has led to the development of novel therapeutic strategies modulating NMDA receptor function. One of these strategies targets the activation of the metabotropic glutamate receptor 5 (mGlu5 receptor) using positive allosteric modulators (PAMs). Our goal was to evaluate the potential for repeated administration of the mGlu5 receptor PAM, CDPPB (3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide) (30 mg/kg) to induce tolerance to the anti-psychotic like effect using the amphetamine-induced hyperlocomotion rat model, and to produce receptor desensitization in mGlu5 receptor-enriched brain regions. CDPPB dose dependently reduced the locomotor response to amphetamine when administered acutely, and the same effect was observed following 7-day pre-treatment regime. In addition, 7-day dosing of CDPPB did not affect mGlu5 receptor density in the striatum, nor did it change mGlu5 receptor PAM-induced phosphorylation of NMDA, GluN1 and GluN2b, receptor subunits in striatum compared to the levels measured acutely. In contrast, in the frontal cortex, repeated administration of CDPPB decreased mGlu5 receptor density and resulted in a loss of its ability to increase GluN1 and GluN2b levels. Consistent with a reduction of cortical mGlu5 receptor density and phosphorylation, CDPPB (30 mg/kg) significantly affected sleep architecture as determined by cortical EEG at day one however by the seventh day of dosing all sleep changes were absent. Together these results suggest that the development of tolerance induced by the repeated treatment with the mGlu5 receptor PAM, CDPPB, may depend not only on the system being measured (sleep architecture vs psychostimulant induced hyperactivity), but also on the brain region involved with frontal cortex being a more susceptible region to receptor desensitization and internalization than striatum.
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Nicoletti F, Bockaert J, Collingridge GL, Conn PJ, Ferraguti F, Schoepp DD, Wroblewski JT, Pin JP. Metabotropic glutamate receptors: from the workbench to the bedside. Neuropharmacology 2010; 60:1017-41. [PMID: 21036182 DOI: 10.1016/j.neuropharm.2010.10.022] [Citation(s) in RCA: 476] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 10/15/2010] [Accepted: 10/21/2010] [Indexed: 12/24/2022]
Abstract
Metabotropic glutamate (mGlu) receptors were discovered in the mid 1980s and originally described as glutamate receptors coupled to polyphosphoinositide hydrolysis. Almost 6500 articles have been published since then, and subtype-selective mGlu receptor ligands are now under clinical development for the treatment of a variety of disorders such as Fragile-X syndrome, schizophrenia, Parkinson's disease and L-DOPA-induced dyskinesias, generalized anxiety disorder, chronic pain, and gastroesophageal reflux disorder. Prof. Erminio Costa was linked to the early times of the mGlu receptor history, when a few research groups challenged the general belief that glutamate could only activate ionotropic receptors and all metabolic responses to glutamate were secondary to calcium entry. This review moves from those nostalgic times to the most recent advances in the physiology and pharmacology of mGlu receptors, and highlights the role of individual mGlu receptor subtypes in the pathophysiology of human disorders. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.
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Affiliation(s)
- F Nicoletti
- Department of Physiology and Pharmacology, University of Rome, Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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Krystal JH, Mathew SJ, D'Souza DC, Garakani A, Gunduz-Bruce H, Charney DS. Potential psychiatric applications of metabotropic glutamate receptor agonists and antagonists. CNS Drugs 2010; 24:669-93. [PMID: 20658799 DOI: 10.2165/11533230-000000000-00000] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Drugs acting at metabotropic glutamate receptors (mGluRs) are among the most promising agents under development for the treatment of psychiatric disorders. The research in this area is at a relatively early stage, as there are no drugs acting at mGluRs that have been approved for the treatment of any psychiatric disorder. However, in the areas of schizophrenia, anxiety disorders and mood disorders, research conducted in animal models appears to translate well into efficacy in human laboratory-based models of psychopathology and in preliminary clinical trials. Further, the genes coding for mGluRs are implicated in the risk for a growing number of psychiatric disorders. This review highlights the best studied mGluR strategies for psychiatry, based on human molecular genetics, studies in animal models and preliminary clinical trials. It describes the potential value of mGluR2 and mGluR5 agonists and positive allosteric modulators for the treatment of schizophrenia. It also reviews evidence that group II mGluR agonists and positive allosteric modulators as well as group I mGluR antagonists might also treat anxiety disorders and some forms of depression, while mGluR2 and group I mGluR antagonists (particularly mGluR5 antagonists) might have antidepressant properties. This review also links growing insights into the role of glutamate in the pathophysiology of these disorders to hypothesized mGluR-related treatment mechanisms.
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Affiliation(s)
- John H Krystal
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA.
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Silverman JL, Tolu SS, Barkan CL, Crawley JN. Repetitive self-grooming behavior in the BTBR mouse model of autism is blocked by the mGluR5 antagonist MPEP. Neuropsychopharmacology 2010; 35:976-89. [PMID: 20032969 PMCID: PMC2827881 DOI: 10.1038/npp.2009.201] [Citation(s) in RCA: 320] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Autism is a neurodevelopmental disorder characterized by abnormal reciprocal social interactions, communication deficits, and repetitive behaviors with restricted interests. BTBR T+tf/J (BTBR) is an inbred mouse strain that shows robust behavioral phenotypes with analogies to all three of the diagnostic symptoms of autism, including well-replicated deficits in reciprocal social interactions and social approach, unusual patterns of ultrasonic vocalization, and high levels of repetitive self-grooming. These phenotypes offer straightforward behavioral assays for translational investigations of pharmacological compounds. Two suggested treatments for autism were evaluated in the BTBR mouse model. Methyl-6-phenylethynyl-pyridine (MPEP), an antagonist of the mGluR5 metabotropic glutamate receptor, blocks aberrant phenotypes in the Fmr1 mouse model of Fragile X, a comorbid neurodevelopmental disorder with autistic features. Risperidone has been approved by the United States Food and Drug Administration for the treatment of irritability, tantrums, and self-injurious behavior in autistic individuals. We evaluated the actions of MPEP and risperidone on two BTBR phenotypes, low sociability and high repetitive self-grooming. Open field activity served as an independent control for non-social exploratory activity and motor functions. C57BL/6J (B6), an inbred strain with high sociability and low self-grooming, served as the strain control. MPEP significantly reduced repetitive self-grooming in BTBR, at doses that had no sedating effects on open field activity. Risperidone reduced repetitive self-grooming in BTBR, but only at doses that induced sedation in both strains. No overall improvements in sociability were detected in BTBR after treatment with either MPEP or risperidone. Our findings suggest that antagonists of mGluR5 receptors may have selective therapeutic efficacy in treating repetitive behaviors in autism.
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Affiliation(s)
- Jill L Silverman
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA.
| | - Seda S Tolu
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research Center, Bethesda, MD, USA
| | - Charlotte L Barkan
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research Center, Bethesda, MD, USA
| | - Jacqueline N Crawley
- Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research Center, Bethesda, MD, USA
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Platt DM, Rowlett JK, Spealman RD. Attenuation of cocaine self-administration in squirrel monkeys following repeated administration of the mGluR5 antagonist MPEP: comparison with dizocilpine. Psychopharmacology (Berl) 2008; 200:167-76. [PMID: 18509621 PMCID: PMC2536745 DOI: 10.1007/s00213-008-1191-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Accepted: 04/26/2008] [Indexed: 10/22/2022]
Abstract
RATIONALE The mGluR5 antagonist MPEP has effects that suggest potential as a pharmacotherapy for cocaine addiction. MPEP can attenuate self-administration of cocaine in animals; however, studies usually involved only acute treatment with MPEP and a single dose of self-administered cocaine. Cocaine addicts use varied amounts of cocaine over long periods of time, and an effective pharmacotherapy would almost certainly require more chronic treatment. OBJECTIVES The present study (1) compared the effects of repeated treatment with MPEP or the NMDA receptor antagonist dizocilpine on the reinforcing effects of a range of doses of cocaine and (2) determined the pharmacological specificity of the effects of the drugs in attenuating cocaine self-administration compared to food-reinforced behavior. An effective pharmacotherapy should selectively reduce cocaine self-administration. MATERIALS AND METHODS Groups of monkeys responded under a fixed-ratio schedule of i.v. cocaine self-administration or food-pellet delivery. The effects of daily treatment with MPEP and dizocilpine were determined under both the schedule of i.v. cocaine injection and food delivery. RESULTS Treatment with MPEP and dizocilpine significantly reduced cocaine self-administration, producing rightward and downward shifts in the ascending limb of the cocaine dose-response function. MPEP and dizocilpine selectively and significantly attenuated self-administration of a low reinforcing dose of cocaine compared to food without evidence of tolerance. CONCLUSIONS Both MPEP and dizocilpine functioned as partially surmountable antagonists of the reinforcing effects of cocaine. The similar effects of the two drugs raises the possibility that MPEP attenuated the reinforcing effects of cocaine, at least in part, via mGluR5-mediated inhibition of NMDA receptor activity.
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Affiliation(s)
- Donna M Platt
- New England Primate Research Center, Harvard Medical School, One Pine Hill Drive, P.O. Box 9102, Southborough, MA 01772-9102, USA.
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Metabotropic glutamate receptor modulation, translational methods, and biomarkers: relationships with anxiety. Psychopharmacology (Berl) 2008; 199:389-402. [PMID: 18322676 DOI: 10.1007/s00213-008-1096-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 01/28/2008] [Indexed: 01/31/2023]
Abstract
RATIONALE The increasing awareness of the need to align clinical and preclinical research to facilitate rapid development of new drug therapies is reflected in the recent introduction of the term "translational medicine". This review examines the implications of translational medicine for psychiatric disorders, focusing on metabotropic glutamate (mGlu) receptor biology in anxiety disorders and on anxiety-related biomarkers. OBJECTIVES This review aims to (1) examine recent progress in translational medicine, emphasizing the role that translational research has played in understanding of the potential of mGlu receptor agonists and antagonists as anxiolytics, (2) identify lacunas where animal and human research have yet to be connected, and (3) suggest areas where translational research can be further developed. RESULTS Current data show that animal and human mGlu(5) binding can be directly compared in experiments using the PET ligand (11)C-ABP688. Testing of the mGlu(2/3) receptor agonist LY354740 in the fear-potentiated startle paradigm allows direct functional comparisons between animals and humans. LY354740 has been tested in panic models, but in different models in rats and humans, hindering efforts at translation. Other potentially translatable methods, such as stress-induced hyperthermia and HPA-axis measures, either have been underexploited or are associated with technical difficulties. New techniques such as quantitative trait loci (QTL) analysis may be useful for generating novel biomarkers of anxiety. CONCLUSIONS Translational medicine approaches can be valuable to the development of anxiolytics, but the amount of cross-fertilization between clinical and pre-clinical departments will need to be expanded to realize the full potential of these approaches.
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Gass JT, Olive MF. Transcriptional profiling of the rat frontal cortex following administration of the mGlu5 receptor antagonists MPEP and MTEP. Eur J Pharmacol 2008; 584:253-62. [PMID: 18346726 DOI: 10.1016/j.ejphar.2008.02.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 01/16/2008] [Accepted: 02/12/2008] [Indexed: 10/22/2022]
Abstract
The development of selective type 5 metabotropic glutamate receptor (mGlu5) antagonists, such as 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP), has revealed an important role for these receptors in various disorders of the nervous system including depression, anxiety, epilepsy, Parkinson's disease, drug addiction, and alcoholism. In this study, we used microarray technology to examine changes in gene expression induced by repeated administration of the mGlu5 antagonists MPEP and MTEP. Male Wistar rats (n=5 per treatment group) were administered MPEP (10 mg/kg), MTEP (10 mg/kg) or vehicle intraperitoneally twice daily for 5 days. Approximately 30 min following the final drug administration, rats were sacrificed and frontal cortices were then dissected and examined for changes in gene expression by cDNA microarray analysis. Changes in gene expression with p-values less than 0.01 were considered to be statistically significant. The expression of 63 genes was changed by both MPEP and MTEP, with 58 genes down-regulated and 5 genes up-regulated. Quantitative PCR verified the magnitude and direction of change in expression of 9 of these genes (r2=0.556, p=0.017). Pathway analysis revealed that many of the biological processes altered by repeated MPEP and MTEP treatment were related to ATP synthesis, hydrolase activity, and signaling pathways associated with mitogen-activated protein kinase (MAPK). Our results demonstrate diverse effects of MPEP and MTEP gene expression in the frontal cortex, and these results may help elucidate the mechanisms by which these compounds produce beneficial effects in animal models of various disorders of the central nervous system.
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Affiliation(s)
- Justin T Gass
- Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, 29425, USA
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Chapter 4.4 The glutamatergic system as a potential therapeutic target for the treatment of anxiety disorders. HANDBOOK OF ANXIETY AND FEAR 2008. [DOI: 10.1016/s1569-7339(07)00013-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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