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Millard SJ, Bearden CE, Karlsgodt KH, Sharpe MJ. The prediction-error hypothesis of schizophrenia: new data point to circuit-specific changes in dopamine activity. Neuropsychopharmacology 2022; 47:628-640. [PMID: 34588607 PMCID: PMC8782867 DOI: 10.1038/s41386-021-01188-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/23/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023]
Abstract
Schizophrenia is a severe psychiatric disorder affecting 21 million people worldwide. People with schizophrenia suffer from symptoms including psychosis and delusions, apathy, anhedonia, and cognitive deficits. Strikingly, schizophrenia is characterised by a learning paradox involving difficulties learning from rewarding events, whilst simultaneously 'overlearning' about irrelevant or neutral information. While dysfunction in dopaminergic signalling has long been linked to the pathophysiology of schizophrenia, a cohesive framework that accounts for this learning paradox remains elusive. Recently, there has been an explosion of new research investigating how dopamine contributes to reinforcement learning, which illustrates that midbrain dopamine contributes in complex ways to reinforcement learning, not previously envisioned. This new data brings new possibilities for how dopamine signalling contributes to the symptomatology of schizophrenia. Building on recent work, we present a new neural framework for how we might envision specific dopamine circuits contributing to this learning paradox in schizophrenia in the context of models of reinforcement learning. Further, we discuss avenues of preclinical research with the use of cutting-edge neuroscience techniques where aspects of this model may be tested. Ultimately, it is hoped that this review will spur to action more research utilising specific reinforcement learning paradigms in preclinical models of schizophrenia, to reconcile seemingly disparate symptomatology and develop more efficient therapeutics.
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Affiliation(s)
- Samuel J. Millard
- grid.19006.3e0000 0000 9632 6718Department of Psychology, University of California, Los Angeles, CA 90095 USA
| | - Carrie E. Bearden
- grid.19006.3e0000 0000 9632 6718Department of Psychology, University of California, Los Angeles, CA 90095 USA ,grid.19006.3e0000 0000 9632 6718Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA 90095 USA
| | - Katherine H. Karlsgodt
- grid.19006.3e0000 0000 9632 6718Department of Psychology, University of California, Los Angeles, CA 90095 USA ,grid.19006.3e0000 0000 9632 6718Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA 90095 USA
| | - Melissa J. Sharpe
- grid.19006.3e0000 0000 9632 6718Department of Psychology, University of California, Los Angeles, CA 90095 USA
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Ashby DM, Dias C, Aleksandrova LR, Lapish CC, Wang YT, Phillips AG. Disruption of Long-Term Depression Potentiates Latent Inhibition: Key Role for Central Nucleus of the Amygdala. Int J Neuropsychopharmacol 2021; 24:580-591. [PMID: 33693669 PMCID: PMC8299826 DOI: 10.1093/ijnp/pyab011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/19/2021] [Accepted: 03/05/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Latent inhibition (LI) reflects an adaptive form of learning impaired in certain forms of mental illness. Glutamate receptor activity is linked to LI, but the potential role of synaptic plasticity remains unspecified. METHODS Accordingly, the present study examined the possible role of long-term depression (LTD) in LI induced by prior exposure of rats to an auditory stimulus used subsequently as a conditional stimulus to signal a pending footshock. We employed 2 mechanistically distinct LTD inhibitors, the Tat-GluA23Y peptide that blocks endocytosis of the GluA2-containing glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, or the selective glutamate n-methyl-d-aspartate receptor 2B antagonist, Ro25-6981, administered prior to the acquisition of 2-way conditioned avoidance with or without tone pre-exposure. RESULTS Systemic LTD blockade with the Tat-GluA23Y peptide strengthened the LI effect by further impairing acquisition of conditioned avoidance in conditional stimulus-preexposed rats compared with normal conditioning in non-preexposed controls. Systemic Ro25-6981 had no significant effects. Brain region-specific microinjections of the Tat-GluA23Y peptide into the nucleus accumbens, medial prefrontal cortex, or central or basolateral amygdala demonstrated that disruption of glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor endocytosis in the central amygdala also potentiated the LI effect. CONCLUSIONS These data revealed a previously unknown role for central amygdala LTD in LI as a key mediator of cognitive flexibility required to respond to previously irrelevant stimuli that acquire significance through reinforcement. The findings may have relevance both for our mechanistic understanding of LI and its alteration in disease states such as schizophrenia, while further elucidating the role of LTD in learning and memory.
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Affiliation(s)
- Donovan M Ashby
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Carine Dias
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Lily R Aleksandrova
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Christopher C Lapish
- Department of Psychology, Indiana University - Purdue University Indianapolis, Indianapolis, IN, United States
| | - Yu Tian Wang
- Department of Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Anthony G Phillips
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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Granger KT, Talwar A, Barnett JH. Latent inhibition and its potential as a biomarker for schizophrenia. Biomark Neuropsychiatry 2020. [DOI: 10.1016/j.bionps.2020.100025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Matveeva TM, Pisansky MT, Young A, Miller RF, Gewirtz JC. Sociality deficits in serine racemase knockout mice. Brain Behav 2019; 9:e01383. [PMID: 31515952 PMCID: PMC6790321 DOI: 10.1002/brb3.1383] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 06/25/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Studies of schizophrenia have pointed to the role of glutamate in its pathophysiology. Mice lacking D-serine show impairments in neurotransmission through NMDA receptors and display behaviors consistent with features of schizophrenia. Yet, socio-communicative deficits, a characteristic of schizophrenia, have not been reported in serine racemase knockout mice. METHODS We use behavioral testing (the three-chambered social approach task, the dyadic interaction task, and the novel object recognition task) to examine socio-communicative behaviors in these mice. RESULTS Serine racemase mice show abnormal social investigation and approach behavior, and differ from wild-type controls in the duration and number of vocalizations they emit in the presence of a conspecific. Serine racemase knockout mice were not impaired in a cognitive test (novel object recognition), although they displayed abnormal behavior in the acquisition phase of the task. CONCLUSIONS Serine racemase knockout mice demonstrate abnormalities in socio-communicative behaviors consistent with an impairment in sociality, a negative symptom of schizophrenia.
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Affiliation(s)
- Tatyana M Matveeva
- Department of Psychology, University of Minnesota - Twin Cities, Minneapolis, Minnesota
| | - Marc T Pisansky
- Department of Neuroscience, University of Minnesota - Twin Cities, Minneapolis, Minnesota
| | - Amy Young
- Department of Psychology, University of Minnesota - Twin Cities, Minneapolis, Minnesota
| | - Robert F Miller
- Department of Neuroscience, University of Minnesota - Twin Cities, Minneapolis, Minnesota
| | - Jonathan C Gewirtz
- Department of Psychology, University of Minnesota - Twin Cities, Minneapolis, Minnesota.,Department of Neuroscience, University of Minnesota - Twin Cities, Minneapolis, Minnesota
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Immune activation in lactating dams alters sucklings' brain cytokines and produces non-overlapping behavioral deficits in adult female and male offspring: A novel neurodevelopmental model of sex-specific psychopathology. Brain Behav Immun 2017; 63:35-49. [PMID: 28189716 DOI: 10.1016/j.bbi.2017.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 12/26/2016] [Accepted: 01/23/2017] [Indexed: 01/04/2023] Open
Abstract
Early immune activation (IA) in rodents, prenatal through the mother or early postnatal directly to the neonate, is widely used to produce behavioral endophenotypes relevant to schizophrenia and depression. Given that maternal immune response plays a crucial role in the deleterious effects of prenatal IA, and lactation is a critical vehicle of immunological support to the neonate, we predicted that immune activation of the lactating dam will produce long-term abnormalities in the sucklings. Nursing dams were injected on postnatal day 4 with the viral mimic poly-I:C (4mg/kg) or saline. Cytokine assessment was performed in dams' plasma and milk 2h, and in the sucklings' hippocampus, 6h and 24h following poly-I:C injection. Male and female sucklings were assessed in adulthood for: a) performance on behavioral tasks measuring constructs considered relevant to schizophrenia (selective attention and executive control) and depression (despair and anhedonia); b) response to relevant pharmacological treatments; c) brain structural changes. Maternal poly-I:C injection caused cytokine alterations in the dams' plasma and milk, as well as in the sucklings' hippocampus. Lactational poly-I:C exposure led to sex-dimorphic (non-overlapping) behavioral abnormalities in the adult offspring, with male but not female offspring exhibiting attentional and executive function abnormalities (manifested in persistent latent inhibition and slow reversal) and hypodopaminergia, and female but not male offspring exhibiting despair and anhedonia (manifested in increased immobility in the forced swim test and reduced saccharine preference) and hyperdopaminergia, mimicking the known sex-bias in schizophrenia and depression. The behavioral double-dissociation predicted distinct pharmacological profiles, recapitulating the pharmacology of negative/cognitive symptoms and depression. In-vivo imaging revealed hippocampal and striatal volume reductions in both sexes, as found in both disorders. This is the first evidence for the emergence of long-term behavioral and brain abnormalities after lactational exposure to an inflammatory agent, supporting a causal link between early immune activation and disrupted neuropsychodevelopment. That such exposure produces schizophrenia- or depression-like phenotype depending on sex, resonates with notions that risk factors are transdiagnostic, and that sex is a susceptibility factor for neurodevelopmental psychopathologies.
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Leading compounds for the validation of animal models of psychopathology. Cell Tissue Res 2013; 354:309-30. [DOI: 10.1007/s00441-013-1692-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/01/2013] [Indexed: 12/18/2022]
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Mihali A, Subramani S, Kaunitz G, Rayport S, Gaisler-Salomon I. Modeling resilience to schizophrenia in genetically modified mice: a novel approach to drug discovery. Expert Rev Neurother 2012; 12:785-99. [PMID: 22853787 DOI: 10.1586/ern.12.60] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Complex psychiatric disorders, such as schizophrenia, arise from a combination of genetic, developmental, environmental and social factors. These vulnerabilities can be mitigated by adaptive factors in each of these domains engendering resilience. Modeling resilience in mice using transgenic approaches offers a direct path to intervention, as resilience mutations point directly to therapeutic targets. As prototypes for this approach, we discuss the three mouse models of schizophrenia resilience, all based on modulating glutamatergic synaptic transmission. This motivates the broader development of schizophrenia resilience mouse models independent of specific pathophysiological hypotheses as a strategy for drug discovery. Three guiding validation criteria are presented. A resilience-oriented approach should identify pharmacologically tractable targets and in turn offer new insights into pathophysiological mechanisms.
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Affiliation(s)
- Andra Mihali
- Department of Psychiatry, Columbia University, New York State Psychiatric Institute, 1051 Riverside Drive, Unit 62, New York, NY 10032, USA
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Balla A, Schneider S, Sershen H, Javitt DC. Effects of novel, high affinity glycine transport inhibitors on frontostriatal dopamine release in a rodent model of schizophrenia. Eur Neuropsychopharmacol 2012; 22:902-10. [PMID: 22561005 PMCID: PMC3882073 DOI: 10.1016/j.euroneuro.2012.03.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 03/11/2012] [Accepted: 03/13/2012] [Indexed: 12/26/2022]
Abstract
Dopaminergic hyperactivity within frontostriatal brain systems is a key feature of schizophrenia, and an objective neural correlate of positive schizophrenia symptoms. N-methyl-d-aspartate (NMDA) receptors are known to play a prominent role in regulation of frontostriatal dopamine release. Furthermore, disturbances in glutamatergic function are increasingly being linked to pathophysiology of both positive and negative symptoms of schizophrenia. Prior studies have demonstrated that subchronic continuous administration of the NMDA antagonist phencyclidine (PCP) induces schizophrenia-like hyper-reactivity of frontostriatal dopamine release to amphetamine (AMPH) in rodents, and that effects were reversed by glycine and the prototypic glycine transport inhibitor (GTI) NFPS. The present study investigates effectiveness of the novel, high affinity and well tolerated GTIs, R231857, R231860 and Org29335, to reverse schizophrenia-like enhancement of AMPH-induced DA release, along with effects of the partial glycine-site agonist d-cycloserine. As previously, PCP had no significant effect on basal DA levels, but significantly enhanced AMPH-induced DA release in prefrontal cortex. All GTIs tested, as well as d-cycloserine, significantly reduced PCP-induced enhancement of DA release in prefrontal cortex. Neither PCP nor GTIs significantly affected striatal DA release. Overall, these findings suggest that treatments which target the glycine modulatory site of the NMDA receptor may significantly reverse NMDA receptor antagonist-induced dysregulation of frontal DA systems, consistent with potential beneficial effects on positive-, in addition to negative-, symptoms of schizophrenia.
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Affiliation(s)
- Andrea Balla
- Translational Schizophrenia Research Center, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
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Baker KD, McNally GP, Richardson R. D-cycloserine does not facilitate fear extinction by reducing conditioned stimulus processing or promoting conditioned inhibition to contextual cues. Learn Mem 2012; 19:461-9. [PMID: 22984284 DOI: 10.1101/lm.026674.112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The NMDA receptor partial agonist d-cycloserine (DCS) enhances the extinction of learned fear in rats and exposure therapy in humans with anxiety disorders. Despite these benefits, little is known about the mechanisms by which DCS promotes the loss of fear. The present study examined whether DCS augments extinction retention (1) through reductions in conditioned stimulus (CS) processing or (2) by promoting the development of conditioned inhibition to contextual cues. Rats administered DCS prior to extinction showed enhanced long-term extinction retention (Experiments 3 and 4). The same nonreinforced CS procedure used in extinction also reduced freezing at test when presented as pre-exposure before conditioning, demonstrating latent inhibition (Experiment 1). DCS administered shortly prior to pre-exposure had no effect on latent inhibition using parameters which produced weak (Experiment 2) or strong (Experiment 3) expression of latent inhibition. Therefore, DCS facilitated learning involving CS-alone exposures, but only when these exposures occurred after (extinction) and not before (latent inhibition) conditioning. We also used a retardation test procedure to examine whether the extinction context gained inhibitory properties for rats given DCS prior to extinction. With three different footshock intensities, there was no evidence that DCS promoted accrual of associative inhibition to the extinction context (Experiment 4). The present findings demonstrate that DCS does not facilitate extinction by reducing CS processing or causing the extinction context to become a conditioned inhibitor. Investigations into the mechanisms underlying the augmentation of extinction by DCS are valuable for understanding how fear can be inhibited.
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Affiliation(s)
- Kathryn D Baker
- School of Psychology, The University of New South Wales, Sydney 2052, Australia.
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Effect of the NMDA antagonist MK-801 on latent inhibition of fear conditioning. Pharmacol Biochem Behav 2012; 102:488-94. [PMID: 22735831 DOI: 10.1016/j.pbb.2012.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 05/22/2012] [Accepted: 06/19/2012] [Indexed: 11/21/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors seem to play a central role in learning and memory processes involved in Latent Inhibition (LI). In fact, MK-801, a non-competitive NMDA receptor antagonist, has proved its effectiveness as a drug for attenuating LI when administered before or after stimulus preexposure and conditioning stages. This paper presents three experiments designed to analyze the effect of MK-801 on LI when the drug is administered before (Experiment 1A) or after (Experiment 1B) preexposure and conditioning stages with a conditioned emotional response procedure. Additionally, we analyze the effect of the drug when it was administered before preexposure, before conditioning or before both phases (Experiment 2). The results show that the effect of the drug varied as a function of the dose (with only the highest dose being effective), the moment of administration (with only the drug administered before the experimental treatments being effective), and the phase of procedure (reducing LI when the drug was administered only at preexposure, and disrupting fear conditioning when administered at conditioning). These differences may be due to several factors ranging from the role played by NMDA receptors in the processing of stimuli of different sensorial modalities to the molecular processes triggered by drug administration.
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Memory encoding in hippocampal ensembles is negatively influenced by cannabinoid CB1 receptors. Behav Pharmacol 2011; 22:335-46. [PMID: 21558844 DOI: 10.1097/fbp.0b013e3283473bfd] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
It has previously been demonstrated that the detrimental effect on the performance of a delayed nonmatch to sample (DNMS) memory task by exogenously administered cannabinoid (CB1) receptor agonist, WIN 55212-2 (WIN), is reversed by the receptor antagonist rimonabant. In addition, rimonabant administered alone elevates DNMS performance, presumably through the suppression of negative modulation by released endocannabinoids during normal task performance. Other investigations have shown that rimonabant enhances encoding of DNMS task-relevant information on a trial-by-trial, delay-dependent basis. In this study, these reciprocal pharmacological actions were completely characterized by long-term, chronic intrahippocampal infusion of both agents (WIN and rimonabant) in successive 2-week intervals. Such long-term exposure allowed extraction and confirmation of task-related firing patterns, in which rimonabant reversed the effects of CB1 agonists. This information was then utilized to artificially impose the facilitatory effects of rimonabant and to reverse the effects of WIN on DNMS performance, by delivering multichannel electrical stimulation in the same firing patterns to the same hippocampal regions. Direct comparison of normal and WIN-injected subjects, in which rimonabant injections and ensemble firing facilitated performance, verified reversal of the modulation of hippocampal memory processes by CB1 receptor agonists, including released endocannabinoids.
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The M₁/M₄ preferring agonist xanomeline reverses amphetamine-, MK801- and scopolamine-induced abnormalities of latent inhibition: putative efficacy against positive, negative and cognitive symptoms in schizophrenia. Int J Neuropsychopharmacol 2011; 14:1233-46. [PMID: 21211109 DOI: 10.1017/s1461145710001549] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A major challenge in developing schizophrenia pharmacotherapy is treating the different symptoms of this disorder, typically divided into positive, negative and cognitive symptoms. M₁/M₄ muscarinic acetylcholine receptor (mAChR) agonists have emerged as a promising therapeutic target, particularly for positive and cognitive symptoms. Here, we examined the activity of the M₁/M₄ mAChR-preferring agonist xanomeline in four pharmacological latent inhibition (LI) models. LI is the poorer conditioning to a stimulus previously experienced as irrelevant during repeated non-reinforced pre-exposure to that stimulus. No-drug controls displayed LI if non-reinforced pre-exposure to a tone was followed by weak, but not strong, conditioning (2 vs. 5 tone-shock pairings). Amphetamine (1 mg/kg)- or scopolamine (0.15 mg/kg)-treated rats failed to show LI with weak conditioning, whereas MK801 (0.05 mg/kg)- or scopolamine (1.5 mg/kg)-treated rats persisted in displaying LI with strong conditioning. Xanomeline (5 mg/kg, 15 mg/kg) reversed amphetamine- and scopolamine-induced LI disruption, effects considered predictive of activity against positive symptoms of schizophrenia. In addition, xanomeline alleviated MK801-induced abnormally persistent LI. Activity of xanomeline on NMDA antagonist-induced behaviour was demonstrated here for the first time and suggests that the drug is effective against negative/cognitive symptoms. Finally, xanomeline alleviated abnormally persistent LI induced by scopolamine, which was suggested to model antipsychotic drug-resistant cognitive impairments, providing further evidence for the cognition-enhancing capacity of xanomeline. Although the use of xanomeline in schizophrenia was discontinued due to cholinergic-related side-effects, our findings suggest that M₁/M₄ mAChR agonism should be an important target in drug development in schizophrenia, potentially beneficial for treatment of positive, negative and cognitive symptoms.
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Barak S, Weiner I. Putative cognitive enhancers in preclinical models related to schizophrenia: The search for an elusive target. Pharmacol Biochem Behav 2011; 99:164-89. [DOI: 10.1016/j.pbb.2011.03.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/27/2011] [Accepted: 03/12/2011] [Indexed: 12/12/2022]
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Hwang R, Souza RP, Tiwari AK, Zai CC, Müller DJ, Potkin SG, Lieberman JA, Meltze HY, Kennedy JL. Gene-gene interaction analyses between NMDA receptor subunit and dopamine receptor gene variants and clozapine response. Pharmacogenomics 2011; 12:277-91. [PMID: 21332319 DOI: 10.2217/pgs.10.182] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIMS To investigate the possible association and gene-gene interaction effects of polymorphisms in NMDA receptor subunit (GRIN1, GRIN2A and GRIN2B) and dopamine receptor (DRD1, DRD2 and DRD3) genes with clozapine response. MATERIALS & METHODS GRIN1 rs11146020 (G1001C), GRIN2A GT-repeat and GRIN2B rs10193895 (G-200T) polymorphisms were tested for association in a Caucasian (n = 183) and an African-American (n = 49) sample using χ(2) and ANOVA tests. Logistic regression and two-way ANOVA were used to explore gene-gene interaction effects with dopamine receptor gene variants. RESULTS & CONCLUSION This study does not support the involvement of the NMDA receptor subunit gene polymorphisms in clozapine response. All tests for an association were negative. Gene-gene interaction analyses however yielded promising leads, including an observed effect between DRD1 rs686 and DRD3 Ser9Gly polymorphisms on clozapine response (p = 0.002).
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Affiliation(s)
- Rudi Hwang
- Neurogenetics Section, Centre for Addiction & Mental Health, 250 College Street, Toronto, Ontario, 5T1R8, Canada.
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Black MD, Stevens RJ, Rogacki N, Featherstone RE, Senyah Y, Giardino O, Borowsky B, Stemmelin J, Cohen C, Pichat P, Arad M, Barak S, De Levie A, Weiner I, Griebel G, Varty GB. AVE1625, a cannabinoid CB1 receptor antagonist, as a co-treatment with antipsychotics for schizophrenia: improvement in cognitive function and reduction of antipsychotic-side effects in rodents. Psychopharmacology (Berl) 2011; 215:149-63. [PMID: 21181124 DOI: 10.1007/s00213-010-2124-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 11/29/2010] [Indexed: 01/05/2023]
Abstract
RATIONALE The psychotomimetic effects of cannabis are believed to be mediated via cannabinoid CB1 receptors. Furthermore, studies have implicated CB1 receptors in the pathophysiology of schizophrenia. OBJECTIVE These studies investigated the effects of the CB1 receptor antagonist, AVE1625, in acute pharmacological and neurodevelopmental models of schizophrenia. AVE1625 was administered to rodents alone or as a co-treatment with clinically used antipsychotic drugs (APDs). METHODS The antipsychotic potential of AVE1625 was tested using psychotomimetic-induced hyperactivity and latent inhibition (LI) deficit models. The procognitive profile was assessed using hole board, novel object recognition, auditory evoked potential, and LI techniques. In addition, the side-effect profile was established by measuring catalepsy, antipsychotic-induced weight gain, plasma levels of prolactin, and anxiogenic potential. RESULTS AVE1625 (1, 3, and 10 mg/kg ip), reversed abnormally persistent LI induced by MK-801 or neonatal nitric oxide synthase inhibition in rodents, and improved both working and episodic memory. AVE1625 was not active in positive symptom models but importantly, it did not diminish the efficacy of APDs. It also decreased catalepsy and weight gain induced by APDs, suggesting that it may decrease APD-induced extrapyramidal side effects (EPS) and compliance. Unlike other CB1 antagonists, AVE1625 did not produce anxiogenic-like effects. CONCLUSIONS These preclinical data suggest that AVE1625 may be useful to treat the cognitive deficits in schizophrenia and as a co-treatment with currently available antipsychotics. In addition, an improved side-effect profile was seen, with potential to ameliorate the EPS and weight gain issues with currently available treatments.
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Bitanihirwe BKY, Peleg-Raibstein D, Mouttet F, Feldon J, Meyer U. Late prenatal immune activation in mice leads to behavioral and neurochemical abnormalities relevant to the negative symptoms of schizophrenia. Neuropsychopharmacology 2010; 35:2462-78. [PMID: 20736993 PMCID: PMC3055332 DOI: 10.1038/npp.2010.129] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Based on the human epidemiological association between prenatal infection and higher risk of schizophrenia, a number of animal models have been established to explore the long-term brain and behavioral consequences of prenatal immune challenge. Accumulating evidence suggests that the vulnerability to specific forms of schizophrenia-related abnormalities is critically influenced by the precise timing of the prenatal immunological insult. In the present study, we tested the hypothesis whether late prenatal immune challenge in mice may induce long-term behavioral and neurochemical dysfunctions primarily associated with the negative symptoms of schizophrenia. We found that prenatal exposure to the viral mimic polyriboinosinic-polyribocytidilic acid (Poly-I:C; 5 mg/kg, i.v.) on gestation day (GD) 17 led to significant deficits in social interaction, anhedonic behavior, and alterations in the locomotor and stereotyped behavioral responses to acute apomorphine (APO) treatment in both male and female offspring. In addition, male but not female offspring born to immune challenged mothers displayed behavioral/cognitive inflexibility as indexed by the presence of an abnormally enhanced latent inhibition (LI) effect. Prenatal immune activation in late gestation also led to numerous, partly sex-specific changes in basal neurotransmitter levels, including reduced dopamine (DA) and glutamate contents in the prefrontal cortex and hippocampus, as well as reduced γ-aminobutyric acid (GABA) and glycine contents in the hippocampus and prefrontal cortex, respectively. The constellation of behavioral and neurochemical abnormalities emerging after late prenatal Poly-I:C exposure in mice leads us to conclude that this immune-based experimental model provides a powerful neurodevelopmental animal model especially for (but not limited to) the negative symptoms of schizophrenia.
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Affiliation(s)
- Byron KY Bitanihirwe
- Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland
| | - Daria Peleg-Raibstein
- Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland
| | - Forouhar Mouttet
- Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland
| | - Joram Feldon
- Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland
| | - Urs Meyer
- Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland,Department of Biology, Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schorenstrasse 16, Schwerzenbach 8603, Switzerland. Tel: +41 44 655 7403; Fax: +41 44 655 7203; E-mail: or
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Sex-dependent antipsychotic capacity of 17β-estradiol in the latent inhibition model: a typical antipsychotic drug in both sexes, atypical antipsychotic drug in males. Neuropsychopharmacology 2010; 35:2179-92. [PMID: 20613719 PMCID: PMC3055319 DOI: 10.1038/npp.2010.89] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The estrogen hypothesis of schizophrenia suggests that estrogen is a natural neuroprotector in women and that exogenous estrogen may have antipsychotic potential, but results of clinical studies have been inconsistent. We have recently shown using the latent inhibition (LI) model of schizophrenia that 17β-estradiol exerts antipsychotic activity in ovariectomized (OVX) rats. The present study sought to extend the characterization of the antipsychotic action of 17β-estradiol (10, 50 and 150 μg/kg) by testing its capacity to reverse amphetamine- and MK-801-induced LI aberrations in gonadally intact female and male rats. No-drug controls of both sexes showed LI, ie, reduced efficacy of a previously non-reinforced stimulus to gain behavioral control when paired with reinforcement, if conditioned with two but not five tone-shock pairings. In both sexes, amphetamine (1 mg/kg) and MK-801 (50 μg/kg) produced disruption (under weak conditioning) and persistence (under strong conditioning) of LI, modeling positive and negative/cognitive symptoms, respectively. 17β-estradiol at 50 and 150 μg/kg potentiated LI under strong conditioning and reversed amphetamine-induced LI disruption in both males and females, mimicking the action of typical and atypical antipsychotic drugs (APDs) in the LI model. 17β-estradiol also reversed MK-induced persistent LI, an effect mimicking atypical APDs and NMDA receptor enhancers, but this effect was observed in males and OVX females but not in intact females. These findings indicate that in the LI model, 17β-estradiol exerts a clear-cut antipsychotic activity in both sexes and, remarkably, is more efficacious in males and OVX females where it also exerts activity considered predictive of anti-negative/cognitive symptoms.
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The role of NMDA receptors in the signal attenuation rat model of obsessive-compulsive disorder. Psychopharmacology (Berl) 2010; 210:13-24. [PMID: 20238210 DOI: 10.1007/s00213-010-1808-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 02/18/2010] [Indexed: 01/12/2023]
Abstract
RATIONALE In recent years, an increasing body of evidence points to the involvement of the glutamatergic system and specifically the glutamatergic ionotropic N-methyl-D-aspartate (NMDA) receptor in the pathophysiology of obsessive-compulsive disorder (OCD). OBJECTIVES To test the role of NMDA receptors in compulsive behavior using the signal attenuation rat model of OCD. In this model, 'compulsive' behavior is induced by attenuating a signal indicating that a lever-press response was effective in producing food. METHODS The NMDA antagonist, MK 801 (0.025-0.100 mg/kg) and the partial NMDA agonist, D-cycloserine (3-100 mg/kg) were administered to rats just before assessing their lever-press responding following signal attenuation (Experiments 1 and 2, respectively). Because the effects of signal attenuation are assessed under extinction conditions, drug doses that were effective in Experiments 1 and 2 were also tested in an extinction session of lever-press responding that was not preceded by signal attenuation (Experiment 3). RESULTS Systemic administration of D: -cycloserine (15 mg/kg) selectively decreased compulsive lever pressing, whereas systemic administration of MK 801 did not affect compulsive lever-pressing but dramatically increased resistance to extinction. CONCLUSIONS Activation of NMDA receptors may have an anti-compulsive effect in OCD patients.
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Dissociating scopolamine-induced disrupted and persistent latent inhibition: stage-dependent effects of glycine and physostigmine. Psychopharmacology (Berl) 2010; 209:175-84. [PMID: 20179909 DOI: 10.1007/s00213-010-1785-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Accepted: 01/21/2010] [Indexed: 10/19/2022]
Abstract
RATIONALE Latent inhibition (LI) is the poorer conditioning to a stimulus seen when conditioning is preceded by repeated non-reinforced pre-exposure to the stimulus. LI indexes the ability to ignore irrelevant stimuli and is used extensively to model attentional impairments in schizophrenia. We showed that the pro-psychotic muscarinic antagonist scopolamine can produce LI disruption or LI persistence depending on dose and stage of administration: low doses disrupt LI acting in the pre-exposure stage of the LI procedure, whereas higher dose produces abnormally persistent LI via action in the conditioning stage. The two LI abnormalities show distinct response to antipsychotic drugs (APDs), with LI disruption, but not LI persistence, reversed by APDs. OBJECTIVES The objective of this study is to show that both LI abnormalities will be reversed by the cognitive enhancers, glycine and physostigmine, in a stage-specific manner, reversing each abnormality via the stage at which it is induced by scopolamine. METHODS LI was measured in a conditioned emotional response procedure. Scopolamine, physostigmine, and glycine were administered in pre-exposure and/or in conditioning. RESULTS Scopolamine (0.15 mg/kg)-induced disrupted LI was reversed by glycine (800 mg/kg) and physostigmine (0.15 mg/kg) via action in pre-exposure, whereas scopolamine (1.5 mg/kg)-induced persistent LI was reversed by these compounds via action in conditioning. In addition, glycine reversed scopolamine-induced disrupted LI via action in conditioning. Finally, glycine failed to reverse amphetamine-induced disrupted LI. CONCLUSIONS These results extend the pharmacological differentiation between scopolamine-induced disrupted and persistent LI and indicate that the scopolamine LI model may have a unique capacity to discriminate between typical APDs, atypical APDs, and cognitive enhancers.
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The glycine transporter-1 inhibitor SSR103800 displays a selective and specific antipsychotic-like profile in normal and transgenic mice. Neuropsychopharmacology 2010; 35:416-27. [PMID: 19759529 PMCID: PMC3055391 DOI: 10.1038/npp.2009.144] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Schizophrenia has been initially associated with dysfunction in dopamine neurotransmission. However, the observation that antagonists of the glutamate N-methyl-D-aspartate (NMDA) receptor produce schizophrenic-like symptoms in humans has led to the idea of a dysfunctioning of the glutamatergic system via its NMDA receptor. As a result, there is a growing interest in the development of pharmacological agents with potential antipsychotic properties that enhance the activity of the glutamatergic system via a modulation of the NMDA receptor. Among them are glycine transporter-1 (GlyT1) inhibitors such as SSR103800, which indirectly enhance NMDA receptor function by increasing the glycine (a co-agonist for the NMDA receptor) levels in the synapse. This study aimed at investigating the potential antipsychotic-like properties of SSR103800, with a particular focus on models of hyperactivity, involving either drug challenge (ie, amphetamine and MK-801) or transgenic mice (ie, NMDA Nr1(neo-/-) and DAT(-/-)). Results showed that SSR103800 (10-30 mg/kg p.o.) blocked hyperactivity induced by the non-competitive NMDA receptor antagonist, MK-801 and partially reversed spontaneous hyperactivity of NMDA Nr1(neo-/-) mice. In contrast, SSR103800 failed to affect hyperactivity induced by amphetamine or naturally observed in dopamine transporter (DAT(-/-)) knockout mice (10-30 mg/kg p.o.). Importantly, both classical (haloperidol) and atypical (olanzapine, clozapine and aripiprazole) antipsychotics were effective in all these models of hyperactivity. However, unlike these latter, SSR103800 did not produce catalepsy (retention on the bar test) up to 30 mg/kg p.o. Together these findings show that the GlyT1 inhibitor, SSR103800, produces antipsychotic-like effects, which differ from those observed with compounds primarily targeting the dopaminergic system, and has a reduced side-effect potential as compared with these latter drugs.
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Castagné V, Moser PC, Porsolt RD. Preclinical behavioral models for predicting antipsychotic activity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2009; 57:381-418. [PMID: 20230767 DOI: 10.1016/s1054-3589(08)57010-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom domains: positive symptoms, negative symptoms, and cognitive impairment. Additionally, treatment with classical antipsychotic medication can be accompanied by important side effects that involve extrapyramidal symptoms (EPS). The discovery of clozapine in the 1970s, which is efficacious in all three symptom domains and has a reduced propensity to induce EPS, has driven research for new antipsychotic agents with a wider spectrum of activity and a lower propensity to induce EPS. The following chapter reviews existing behavioral procedures in animals for their ability to predict compound efficacy against schizophrenia symptoms and liability to induce EPS. Rodent models of positive symptoms include procedures related to hyperfunction in central dopamine and serotonin (5-hydroxytryptamine) systems and hypofunction of central glutamatergic (N-methyl-d-aspartate) neurotransmission. Procedures for evaluating negative symptoms include rodent models of anhedonia, affective flattening, and diminished social interaction. Cognitive deficits can be assessed in rodent models of attention (prepulse inhibition (PPI), latent inhibition) and of learning and memory (passive avoidance, object and social recognition, Morris water maze, and operant-delayed alternation). The relevance of the conditioned avoidance response (CAR) is also discussed. A final section reviews animal procedures for assessing EPS liability, in particular parkinsonism (catalepsy), acute dystonia (purposeless chewing in rodents, dystonia in monkeys), akathisia (defecation in rodents), and tardive dyskinesia (long-term antipsychotic treatment in rodents and monkeys).
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Affiliation(s)
- Vincent Castagné
- Porsolt & Partners Pharmacology, 9 Bis Rue Henri Martin, 92100 Boulogne-Billancourt, France
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Singer P, Feldon J, Yee BK. Are DBA/2 mice associated with schizophrenia-like endophenotypes? A behavioural contrast with C57BL/6 mice. Psychopharmacology (Berl) 2009; 206:677-98. [PMID: 19484222 DOI: 10.1007/s00213-009-1568-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 05/07/2009] [Indexed: 01/02/2023]
Abstract
RATIONALE Due to its intrinsic deficiency in prepulse inhibition (PPI), the inbred DBA/2 mouse strain has been considered as an animal model for evaluating antipsychotic drugs. However, the PPI impairment observed in DBA/2 mice relative to the common C57BL/6 strain is confounded by a concomitant reduction in baseline startle reactivity. In this study, we examined the robustness of the PPI deficit when this confound is fully taken into account. MATERIALS AND METHODS Male DBA/2 and C57BL/6 mice were compared in a PPI experiment using multiple pulse stimulus intensities, allowing the possible matching of startle reactivity prior to examination of PPI. The known PPI-enhancing effect of the antipsychotic, clozapine, was then evaluated in half of the animals, whilst the other half was subjected to two additional schizophrenia-relevant behavioural tests: latent inhibition (LI) and locomotor reaction to the psychostimulants-amphetamine and phencyclidine. RESULTS PPI deficiency in DBA/2 relative to C57BL/6 mice was essentially independent of the strain difference in baseline startle reactivity. Yet, there was no evidence that DBA/2 mice were superior in detecting the PPI-facilitating effect of clozapine when startle difference was balanced. Compared with C57BL/6 mice, DBA/2 mice also showed impaired LI and a different temporal profile in their responses to amphetamine and phencyclidine. CONCLUSION Relative to the C57BL/6 strain, DBA/2 mice displayed multiple behavioural traits relevant to schizophrenia psycho- and physiopathology, indicative of both dopaminergic and glutamatergic/N-methyl-D: -aspartic acid receptor dysfunctions. Further examination of their underlying neurobiological differences is therefore warranted in order to enhance the power of this specific inter-strain comparison as a model of schizophrenia.
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Affiliation(s)
- Philipp Singer
- Laboratory of Behavioural Neurobiology, Federal Institute of Technology Zurich, Schorenstrasse 16, Schwerzenbach, Switzerland
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Labrie V, Wang W, Barger SW, Baker GB, Roder JC. Genetic loss of D-amino acid oxidase activity reverses schizophrenia-like phenotypes in mice. GENES BRAIN AND BEHAVIOR 2009; 9:11-25. [PMID: 19751394 DOI: 10.1111/j.1601-183x.2009.00529.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Reduced function of the N-methyl-d-aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. The NMDAR contains a glycine binding site in its NR1 subunit that may be a useful target for the treatment of schizophrenia. In this study, we assessed the therapeutic potential of long-term increases in the brain levels of the endogenous NMDAR glycine site agonist D-serine, through the genetic inactivation of its catabolic enzyme D-amino acid oxidase (DAO) in mice. The effects of eliminating DAO function were investigated in mice that display schizophrenia-related behavioral deficits due to a mutation (Grin 1(D481N)) in the NR1 subunit that results in a reduction in NMDAR glycine affinity. Grin 1(D481N) mice show deficits in sociability, prolonged latent inhibition, enhanced startle reactivity and impaired spatial memory. The hypofunctional Dao 1(G181R) mutation elevated brain levels of D-serine, but alone it did not affect performance in the behavioral measures. Compared to animals with only the Grin 1(D481N) mutation, mice with both the Dao1(G181R) and Grin 1(D481N) mutations displayed an improvement in social approach and spatial memory retention, as well as a reversal of abnormally persistent latent inhibition and a partial normalization of startle responses. Thus, an increased level of D-serine resulting from decreased catalysis corrected the performance of mice with deficient NMDAR glycine site activation in behavioral tasks relevant to the negative and cognitive symptoms of schizophrenia. Diminished DAO activity and elevations in D-serine may serve as an effective therapeutic intervention for the treatment of psychiatric symptoms.
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Affiliation(s)
- V Labrie
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada.
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Singer P, Feldon J, Yee BK. Interactions between the glycine transporter 1(GlyT1) inhibitor SSR504734 and psychoactive drugs in mouse motor behaviour. Eur Neuropsychopharmacol 2009; 19:571-80. [PMID: 19282154 DOI: 10.1016/j.euroneuro.2009.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/22/2009] [Accepted: 02/17/2009] [Indexed: 11/29/2022]
Abstract
The specific glycine transporter 1 (GlyT1) inhibitor, SSR504734, is highly effective in enhancing N-methyl-D-aspartate receptor (NMDAR) function by elevating the availability of the NMDAR co-agonist, glycine, in the vicinity of NMDAR-containing glutamatergic synapses. According to the glutamatergic hypofunction hypothesis of schizophrenia, SSR504734 may therefore possess antipsychotic potential. Here, we evaluated the effects of SSR504734 in response to three psychomimetic drugs: phencyclidine, amphetamine, and apomorphine in male C57BL/6 mice. SSR504734 attenuated phencyclidine-induced (5 mg/kg, i.p.) hyperlocomotion, but potentiated the motor stimulant and motor depressant effects of amphetamine (2.5 mg/kg, i.p.) and apomorphine (0.75 mg/kg, s.c.), respectively. Hence, SSR504734 not only confers resistance to NMDAR blockade, but also enhances the locomotor response to dopaminergic stimulation. The latter finding adds to reports that SSR504734 may modulate dopamine-mediated behaviour by interference with normal glutamate-dopamine interaction. The specificity of this action of SSR504734 will be highly relevant to its potential application as an antipsychotic agent.
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Affiliation(s)
- Philipp Singer
- Laboratory of Behavioral Neurobiology, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
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Pro-cognitive and antipsychotic efficacy of the alpha7 nicotinic partial agonist SSR180711 in pharmacological and neurodevelopmental latent inhibition models of schizophrenia. Neuropsychopharmacology 2009; 34:1753-63. [PMID: 19158670 DOI: 10.1038/npp.2008.232] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Schizophrenia symptoms can be segregated into positive, negative and cognitive, which exhibit differential sensitivity to drug treatments. Accumulating evidence points to efficacy of alpha7 nicotinic receptor (nAChR) agonists for cognitive deficits in schizophrenia but their activity against positive symptoms is thought to be minimal. The present study examined potential pro-cognitive and antipsychotic activity of the novel selective alpha7 nAChR partial agonist SSR180711 using the latent inhibition (LI) model. LI is the reduced efficacy of a previously non-reinforced stimulus to gain behavioral control when paired with reinforcement, compared with a novel stimulus. Here, no-drug controls displayed LI if non-reinforced pre-exposure to a tone was followed by weak but not strong conditioning (2 vs 5 tone-shock pairings). MK801 (0.05 mg/kg, i.p.) -treated rats as well as rats neonatally treated with nitric oxide synthase inhibitor L-NoArg (10 mg/kg, s.c.) on postnatal days 4-5, persisted in displaying LI with strong conditioning, whereas amphetamine (1 mg/kg) -treated rats failed to show LI with weak conditioning. SSR180711 (0.3, 1, 3 mg/kg, i.p.) was able to alleviate abnormally persistent LI produced by acute MK801 and neonatal L-NoArg; these models are believed to model cognitive aspects of schizophrenia and activity here was consistent with previous findings with alpha7-nAChR agonists. In addition, unexpectedly, SSR180711 (1, 3 mg/kg, i.p.) potentiated LI with strong conditioning in no-drug controls and reversed amphetamine-induced LI disruption, two effects considered predictive of activity against positive symptoms of schizophrenia. These findings suggest that SSR180711 may be beneficial not only for the treatment of cognitive symptoms in schizophrenia, as reported multiple times previously, but also positive symptoms.
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Singer P, Yee BK, Feldon J, Iwasato T, Itohara S, Grampp T, Prenosil G, Benke D, Möhler H, Boison D. Altered mnemonic functions and resistance to N-METHYL-d-Aspartate receptor antagonism by forebrain conditional knockout of glycine transporter 1. Neuroscience 2009; 161:635-54. [PMID: 19332109 DOI: 10.1016/j.neuroscience.2009.03.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 03/17/2009] [Accepted: 03/22/2009] [Indexed: 01/15/2023]
Abstract
Converging evidence from pharmacological and molecular studies has led to the suggestion that inhibition of glycine transporter 1 (GlyT1) constitutes an effective means to boost N-methyl-d-aspartate receptor (NMDAR) activity by increasing the extra-cellular concentration of glycine in the vicinity of glutamatergic synapses. However, the precise extent and limitation of this approach to alter cognitive function, and therefore its potential as a treatment strategy against psychiatric conditions marked by cognitive impairments, remain to be fully examined. Here, we generated mutant mice lacking GlyT1 in the entire forebrain including neurons and glia. This conditional knockout system allows a more precise examination of GlyT1 downregulation in the brain on behavior and cognition. The mutation was highly effective in attenuating the motor-stimulating effect of acute NMDAR blockade by phencyclidine, although no appreciable elevation in NMDAR-mediated excitatory postsynaptic currents (EPSC) was observed in the hippocampus. Enhanced cognitive performance was observed in spatial working memory and object recognition memory while spatial reference memory and associative learning remained unaltered. These findings provide further credence for the potential cognitive enhancing effects of brain GlyT1 inhibition. At the same time, they indicated potential phenotypic differences when compared with other constitutive and conditional GlyT1 knockout lines, and highlighted the possibility of a functional divergence between the neuronal and glia subpopulations of GlyT1 in the regulation of learning and memory processes. The relevance of this distinction to the design of future GlyT1 blockers as therapeutic tools in the treatment of cognitive disorders remains to be further investigated.
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Affiliation(s)
- P Singer
- Laboratory of Behavioral Neurobiology, Federal Institute of Technology (ETH) Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
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Towards an animal model of an antipsychotic drug-resistant cognitive impairment in schizophrenia: scopolamine induces abnormally persistent latent inhibition, which can be reversed by cognitive enhancers but not by antipsychotic drugs. Int J Neuropsychopharmacol 2009; 12:227-41. [PMID: 18687163 DOI: 10.1017/s1461145708009176] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Schizophrenia symptoms segregate into positive, negative and cognitive, which exhibit differential sensitivity to drugs. Recent efforts to identify treatments targeting cognitive impairments in schizophrenia have directed attention to the cholinergic system for its well documented role in cognition. Relatedly, muscarinic antagonists (e.g. scopolamine) produce an 'antimuscarinic syndrome', characterized by psychosis and cognitive impairments. Latent inhibition (LI) is the poorer conditioning to a stimulus resulting from its non-reinforced pre-exposure. LI indexes the ability to ignore irrelevant stimuli and aberrations of this capacity produced by pro-psychotic agents (e.g. amphetamine, MK-801) are used extensively to model attentional impairments in schizophrenia. We recently showed that LI was disrupted by scopolamine at low doses, and this was reversed by typical and atypical antipsychotic drugs (APDs) and the acetylcholinesterase inhibitor physostigmine. Here, at a higher dose (1.5 mg/kg), scopolamine produced an opposite pole of attentional impairment, namely, attentional perseveration, whereby scopolamine-treated rats persisted in expressing LI under strong conditioning that prevented LI expression in controls. Scopolamine-induced persistent LI was reversed by cholinergic and glycinergic cognitive enhancers (physostigmine and glycine) but was resistant to both typical and atypical APDs (haloperidol and clozapine). The latter sets scopolamine-induced persistent LI apart from scopolamine- and amphetamine-induced disrupted LI, which are reversed by both typical and atypical APDs, as well as from other cases of abnormally persistent LI including MK-801-induced persistent LI, which is reversed by atypical APDs. Thus, scopolamine-induced persistent LI may provide a pharmacological LI model for screening cognitive enhancers that are efficient for the treatment of APD-resistant cognitive impairments in schizophrenia.
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Black MD, Varty GB, Arad M, Barak S, De Levie A, Boulay D, Pichat P, Griebel G, Weiner I. Procognitive and antipsychotic efficacy of glycine transport 1 inhibitors (GlyT1) in acute and neurodevelopmental models of schizophrenia: latent inhibition studies in the rat. Psychopharmacology (Berl) 2009; 202:385-96. [PMID: 18709358 DOI: 10.1007/s00213-008-1289-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 07/29/2008] [Indexed: 02/03/2023]
Abstract
RATIONALE SSR103800 and SSR504734 are novel glycine transport 1 (GlyT1) inhibitors with therapeutic potential for the treatment of schizophrenia. OBJECTIVE The present studies investigated the effects of GlyT1 inhibitors in acute pharmacological and neurodevelopmental models of schizophrenia using latent inhibition in the rat; these latent inhibition (LI) models are believed to be predictive for treatments of positive, negative, and cognitive aspects of schizophrenia. MATERIALS AND METHODS LI, the poorer conditioning to a previously irrelevant stimulus, was measured in a conditioned emotional response procedure in male rats. The effects of SSR103800 or SSR504734 (both at 1, 3, and 10 mg/kg, i.p.) were determined on amphetamine-induced disrupted LI, MK-801-induced abnormally persistent LI, and neurodevelopmentally induced abnormally persistent LI in adult animals that had been neonatally treated with a nitric oxide synthase inhibitor. RESULTS SSR103800 (1 and 3 mg/kg) and SSR504734 (1 and 10 mg/kg) potentiated LI under conditions where LI was not present in nontreated controls and SSR103800 (1 mg/kg) reversed amphetamine-induced disrupted LI while not affecting LI on its own. Additionally, SSR103800 (1 and 3 mg/kg) and SSR504734 (3 and 10 mg/kg) reversed abnormally persistent LI induced by MK-801. In the neurodevelopmental model, SSR504734 (3 and 10 mg/kg) reverted the LI back to control (normal) levels. CONCLUSIONS These preclinical data, from acute and neurodevelopmental models, suggest that GlyT1 inhibition may exhibit activity in the positive, negative, and cognitive symptom domains of schizophrenia.
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Affiliation(s)
- Mark D Black
- CNS Department, Sanofi-Aventis, 1041 Route 202/206, Bridgewater, NJ 08807, USA.
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Labrie V, Lipina T, Roder JC. Mice with reduced NMDA receptor glycine affinity model some of the negative and cognitive symptoms of schizophrenia. Psychopharmacology (Berl) 2008; 200:217-30. [PMID: 18597079 DOI: 10.1007/s00213-008-1196-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 04/30/2008] [Indexed: 12/31/2022]
Abstract
RATIONALE Schizophrenic patients demonstrate prominent negative and cognitive symptoms that are poorly responsive to antipsychotic treatment. Abnormal glutamatergic neurotransmission may contribute to these pathophysiological dimensions of schizophrenia. OBJECTIVE We examined the involvement of the glycine coagonist site on the N-methyl-D: -aspartate receptor (NMDAR) glycine coagonist site in the modulation of negative and cognitive endophenotypes in mice. MATERIALS AND METHODS Behavioral phenotypes relevant to schizophrenia were assessed in Grin1(D481N) mice that have reduced NMDAR glycine affinity. RESULTS Grin1(D481N) mutant mice showed abnormally persistent latent inhibition (LI) that was reversed by two agents that enhance NMDAR glycine site function, D: -serine (600 mg/kg) and ALX-5407 (1 mg/kg), and by the classical atypical antipsychotic clozapine (3 mg/kg). Similarly, blockade of the NMDAR glycine site with the antagonist L-701,324 (5 mg/kg) induced persistent LI in C57BL6/J mice. In a social affiliations task, Grin1(D481N) mutant animals showed reduced social approach behaviors that were normalized by D: -serine (600 mg/kg). During a nonassociative spatial object recognition task, mutant mice demonstrated impaired reactivity to a spatial change that was reversible by D: -serine (300 and 600 mg/kg) and clozapine (0.75 mg/kg). In contrast, responses to social novelty and nonspatial change remained unaffected, indicating that the Grin1(D481N) mutation induces selective deficits in sociability and spatial discrimination, while leaving intact the ability to react to novelty. CONCLUSIONS Genetic and pharmacologically induced deficiencies in glycine binding appear to model the impairments in behavioral flexibility, sociability, and spatial recognition related to the negative and cognitive symptoms of schizophrenia. Antipsychotics that target the NMDAR glycine site may be beneficial in treating such psychiatric symptoms.
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Affiliation(s)
- Viviane Labrie
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Room 860, 600 University Avenue, Toronto, ON, Canada, M5G 1X5.
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