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Vojtechova I, Tuckova K, Juza R, Stuchlik A, Kelemen E, Korabecny J, Soukup O, Petrasek T. Dopaminergic and glutamatergic models of psychosis show differential sensitivity to aripiprazole and a novel experimental compound modulating D 2/5-HT receptor activity. Prog Neuropsychopharmacol Biol Psychiatry 2023; 127:110819. [PMID: 37379895 DOI: 10.1016/j.pnpbp.2023.110819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 06/23/2023] [Accepted: 06/25/2023] [Indexed: 06/30/2023]
Abstract
Dopamine type 2 receptors (D2Rs) constitute the main molecular target in the pharmacotherapy of schizophrenia. However, the second and third generation of antipsychotics comprises multi-target ligands, also binding serotonin type 3 receptors (5-HT3Rs) and other receptor classes as well. Here, we examined two experimental compounds (marked compound K1697 and K1700) from the group of 1,4-di-substituted aromatic piperazines, previously described in the study of Juza et al., 2021, and compared them with the chosen reference antipsychotic, aripiprazole. Their efficacy against schizophrenia-like behavior was tested in two different models of psychosis in the rat, induced by acute administration of either amphetamine (1.5 mg/kg) or dizocilpine (0.1 mg/kg), reflecting the dopaminergic and glutamatergic hypotheses of schizophrenia. The two models exhibited broadly similar behavioral manifestations: hyperlocomotion, disrupted social behavior and impaired prepulse inhibition of the startle response. However, they differed in their treatment responses as hyperlocomotion and prepulse inhibition deficit in the dizocilpine model were resistant to antipsychotic treatment, unlike the amphetamine model. One of the experimental compounds, K1700, ameliorated all the observed schizophrenia-like behaviors in the amphetamine model with an efficacy comparable to or greater than aripiprazole. Whereas social impairments caused by dizocilpine were strongly suppressed by aripiprazole, K1700 was less efficient. Taken together, K1700 showed antipsychotic properties comparable to those of aripiprazole, although the efficacy of the two drugs differed in specific domains of behavior and was also model-dependent. Our present results highlight the differences in these two schizophrenia models and their responsiveness to pharmacotherapy, and confirm compound K1700 as a promising drug candidate.
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Affiliation(s)
- Iveta Vojtechova
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic; Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Klara Tuckova
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic
| | - Radomir Juza
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic
| | - Ales Stuchlik
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic; Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Eduard Kelemen
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic
| | - Jan Korabecny
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic
| | - Ondrej Soukup
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic.
| | - Tomas Petrasek
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic; Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic.
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Spironolactone alleviates schizophrenia-related reversal learning in Tcf4 transgenic mice subjected to social defeat. SCHIZOPHRENIA 2022; 8:77. [PMID: 36171421 PMCID: PMC9519974 DOI: 10.1038/s41537-022-00290-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 09/17/2022] [Indexed: 11/08/2022]
Abstract
AbstractCognitive deficits are a hallmark of schizophrenia, for which no convincing pharmacological treatment option is currently available. Here, we tested spironolactone as a repurposed compound in Tcf4 transgenic mice subjected to psychosocial stress. In this ‘2-hit’ gene by environment mouse (GxE) model, the animals showed schizophrenia-related cognitive deficits. We had previously shown that spironolactone ameliorates working memory deficits and hyperactivity in a mouse model of cortical excitatory/inhibitory (E/I) dysbalance caused by an overactive NRG1-ERBB4 signaling pathway. In an add-on clinical study design, we used spironolactone as adjuvant medication to the standard antipsychotic drug aripiprazole. We characterized the compound effects using our previously established Platform for Systematic Semi-Automated Behavioral and Cognitive Profiling (PsyCoP). PsyCoP is a widely applicable analysis pipeline based on the Research Domain Criteria (RDoC) framework aiming at facilitating translation into the clinic. In addition, we use dimensional reduction to analyze and visualize overall treatment effect profiles. We found that spironolactone and aripiprazole improve deficits of several cognitive domains in Tcf4tg x SD mice but partially interfere with each other’s effect in the combination therapy. A similar interaction was detected for the modulation of novelty-induced activity. In addition to its strong activity-dampening effects, we found an increase in negative valence measures as a side effect of aripiprazole treatment in mice. We suggest that repurposed drug candidates should first be tested in an adequate preclinical setting before initiating clinical trials. In addition, a more specific and effective NRG1-ERBB4 pathway inhibitor or more potent E/I balancing drug might enhance the ameliorating effect on cognition even further.
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Quetiapine Ameliorates MIA-Induced Impairment of Sensorimotor Gating: Focus on Neuron-Microglia Communication and the Inflammatory Response in the Frontal Cortex of Adult Offspring of Wistar Rats. Cells 2022; 11:cells11182788. [PMID: 36139363 PMCID: PMC9496681 DOI: 10.3390/cells11182788] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/24/2022] [Accepted: 09/05/2022] [Indexed: 11/17/2022] Open
Abstract
The maternal immune activation produced by the systemic administration of lipopolysaccharide (LPS) in rats provides valuable insights into the basis of behavioural schizophrenia-like disturbances and biochemical changes in the brains of the offspring, such as microglial activation. Regarding therapy, antipsychotics continually constitute the cornerstone of schizophrenia treatment. To their various efficacy and side effects, as well as not fully recognised mechanisms of action, further characteristics have been suggested, including an anti-inflammatory action via the impact on neuron–microglia axes responsible for inhibition of microglial activation. Therefore, in the present study, we sought to determine whether chronic treatment with chlorpromazine, quetiapine or aripiprazole could influence schizophrenia-like behavioural disturbances at the level of sensorimotor gating in male offspring prenatally exposed to LPS. Simultaneously, we wanted to explore if the chosen antipsychotics display a positive impact on the neuroimmunological parameters in the brains of these adult animals with a special focus on the ligand-receptor axes controlling neuron–microglia communication as well as pro- and anti-inflammatory factors related to the microglial activity. The results of our research revealed the beneficial effect of quetiapine on deficits in sensorimotor gating observed in prenatally LPS-exposed offspring. In terms of axes controlling neuron–microglia communication and markers of microglial reactivity, we observed a subtle impact of quetiapine on hippocampal Cx3cl1 and Cx3cr1 levels, as well as cortical Cd68 expression. Hence, further research is required to fully define and explain the involvement of quetiapine and other antipsychotics in Cx3cl1-Cx3cr1 and/or Cd200-Cd200r axes modulation and inflammatory processes in the LPS-based model of schizophrenia-like disturbances.
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Cortez IL, Silva NR, Rodrigues NS, Pedrazzi JFC, Del Bel EA, Mechoulam R, Gomes FV, Guimarães FS. HU-910, a CB2 receptor agonist, reverses behavioral changes in pharmacological rodent models for schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2022; 117:110553. [PMID: 35341823 DOI: 10.1016/j.pnpbp.2022.110553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/05/2022] [Accepted: 03/20/2022] [Indexed: 12/09/2022]
Abstract
Despite attenuating the positive symptoms, drugs currently used to treat schizophrenia frequently do not improve the negative symptoms and cognitive impairments. In addition, they show low tolerability, which has been associated with high rates of treatment discontinuation. Recent evidence suggests that the endocannabinoid system may be a target for schizophrenia treatment. The CB2 receptor modulates dopaminergic neurotransmission, which is abnormally enhanced in schizophrenia patients. Here, we aimed to evaluate whether HU-910, a selective CB2 receptor agonist, would reverse schizophrenia-related behavioral changes observed after the acute injections of amphetamine or the N-methyl-d-aspartate receptor (NMDAR) antagonist MK-801. We also investigated the effects of HU-910 in the memory impairment caused by repeated MK-801 administration. Finally, we tested whether HU-910 would produce the cannabinoid tetrad (catalepsy, hypolocomotion, hypothermia, and antinociception). In male C57BL/6 mice, the acute treatment with HU-910 (30 mg/kg) prevented the hyperlocomotion induced by acute MK-801. This effect was blocked by the CB2 receptor antagonist AM630 (1 mg/kg). On the contrary, HU-910 did not prevent the increased locomotor activity caused by acute amphetamine. The acute treatment with HU-910 (3, 10, and 30 mg/kg) also attenuated the impairments in the prepulse inhibition test induced by acute MK-801 and amphetamine. The repeated treatment with HU-910 attenuated the cognitive impairment caused by chronic administration of MK-801 in the novel object recognition test. Furthermore, HU-910 did not produce the cannabinoid tetrad. These results indicate that HU-910 produced antipsychotic-like effects and support further research on the potential therapeutic properties of this compound to treat schizophrenia.
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Affiliation(s)
- Isadora Lopes Cortez
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
| | - Nicole R Silva
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Naielly S Rodrigues
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Elaine A Del Bel
- Department of Physiology, Ribeirão Preto Dentistry School, University of São Paulo, Brazil
| | - Raphael Mechoulam
- Department of Medicinal Chemistry and Natural Products, Hebrew University Medical Faculty, Jerusalem, Israel
| | - Felipe V Gomes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Francisco S Guimarães
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
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Andrade YCP, Ropke J, Viana TG, Fanelli C, Minaldi E, Batista LA, Issy AC, Del Bel EA, Rodrigues LCM, Liégeois JF, Moreira FA. Effects of JL13, a pyridobenzoxazepine compound, in dopaminergic and glutamatergic models of antipsychotic activity. Behav Pharmacol 2021; 32:2-8. [PMID: 33399294 DOI: 10.1097/fbp.0000000000000595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The pyridobenzoxazepine compound, 5-(4-methylpiperazin-1-yl)-8-chloro-pyrido[2,3-b][1,5]benzoxazepine (JL13), has been developed as a potential antipsychotic drug. We tested the hypothesis that JL13 is efficacious in both dopaminergic and glutamatergic animal models of schizophrenia. We investigated JL13 for its efficacy to prevent cocaine- and ketamine-induced hyperlocomotion and MK-801-induced deficits in prepulse inhibition (PPI) of the startle reflex. Male Swiss mice received injections of JL13 (0.1-10 mg/kg) and were tested in the open field for basal locomotion. In separate experiments, the animals received injections of JL13 (0.1-3 mg/kg) followed by cocaine (10 mg/kg), ketamine (60 mg/kg), or MK-801 (0.5 mg/kg) and were tested in the open field for hyperlocomotion. In addition, it was also tested if JL13 prevented MK-801-induced disruption of PPI. Only the highest dose of JL13 impaired spontaneous locomotion, suggesting its favorable profile regarding motor side effects. At doses that did not impair basal motor activity, JL13 prevented cocaine-, ketamine-, and MK-801-induced hyperlocomotion. Moreover, JL13 prevented MK-801-induced disruption of PPI. Extending previous findings, this study shows that JL13 exerts antipsychotic-like activity in both dopaminergic and glutamatergic models. This compound has a favorable pharmacological profile, similar to second-generation antipsychotics.
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Affiliation(s)
| | - Jivago Ropke
- Department of Pharmacology, Institute of Biological Sciences
| | - Thércia G Viana
- Department of Pharmacology, Institute of Biological Sciences
| | - Chiara Fanelli
- Department of Pharmacology, Institute of Biological Sciences
| | - Elisa Minaldi
- Department of Pharmacology, Institute of Biological Sciences
| | - Luara A Batista
- Department of Pharmacology, Graduate School in Neuroscience, Universidade Federal de Minas Gerais, Belo Horizonte
| | - Ana C Issy
- Departament of Morphology, Estomatology and Basic Pathology, Faculty of Odontology of Ribeirão Preto, Universidade de São Paulo Ribeirão Preto
| | - Elaine A Del Bel
- Departament of Morphology, Estomatology and Basic Pathology, Faculty of Odontology of Ribeirão Preto, Universidade de São Paulo Ribeirão Preto
| | - Lívia C M Rodrigues
- Department of Physiological Sciences, Health Science Center, Universidade Federal do Espírito Santo, Vitória, Brazil
| | - Jean-François Liégeois
- Department of Pharmacy, Laboratory of Medicinal Chemistry, Faculty of Medicine and CIRM, University of Liège, Liège, Belgium
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Dopamine, Cognitive Impairments and Second-Generation Antipsychotics: From Mechanistic Advances to More Personalized Treatments. Pharmaceuticals (Basel) 2020; 13:ph13110365. [PMID: 33167370 PMCID: PMC7694365 DOI: 10.3390/ph13110365] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022] Open
Abstract
The pharmacological treatment of cognitive impairments associated with schizophrenia is still a major unmet clinical need. Indeed, treatments with available antipsychotics generate highly variable cognitive responses among patients with schizophrenia. This has led to the general assumption that antipsychotics are ineffective on cognitive impairment, although personalized medicine and drug repurposing approaches might scale down this clinical issue. In this scenario, evidence suggests that cognitive improvement exerted by old and new atypical antipsychotics depends on dopaminergic mechanisms. Moreover, the newer antipsychotics brexpiprazole and cariprazine, which might have superior clinical efficacy on cognitive deficits over older antipsychotics, mainly target dopamine receptors. It is thus reasonable to assume that despite more than 50 years of elusive efforts to develop novel non-dopaminergic antipsychotics, dopamine receptors remain the most attractive and promising pharmacological targets in this field. In the present review, we discuss preclinical and clinical findings showing dopaminergic mechanisms as key players in the cognitive improvement induced by both atypical antipsychotics and potential antipsychotics. We also emphasize the concept that these mechanistic advances, which help to understand the heterogeneity of cognitive responses to antipsychotics, may properly guide treatment decisions and address the unmet medical need for the management of cognitive impairment associated with schizophrenia.
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Effect of combined treatment with aripiprazole and antidepressants on the MK-801-induced deficits in recognition memory in novel recognition test and on the release of monoamines in the rat frontal cortex. Behav Brain Res 2020; 393:112769. [PMID: 32535184 DOI: 10.1016/j.bbr.2020.112769] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/11/2020] [Accepted: 05/13/2020] [Indexed: 01/23/2023]
Abstract
According to preclinical and clinical studies, the antidepressant-induced increase in the activity of atypical antipsychotics may efficiently improve the treatment of negative and some cognitive symptoms of schizophrenia. In the present study, we aimed to evaluate the effects of the antidepressants escitalopram and mirtazapine and the atypical antipsychotic drug aripiprazole, administered separately or in combination, on the MK-801-induced deficits in the recognition memory test and on the extracellular levels of monoamines and their metabolites in the rat frontal cortex. Based on the results of the behavioral tests, co-treatment with an ineffective dose of aripiprazole (0.1 mg/kg) and escitalopram (2.5 and 5 mg/kg) or mirtazapine (5 mg/kg) abolished the deficits evoked by MK-801 in the novel object recognition test, and those effects were blocked by the 5-HT1A receptor antagonist (WAY 100,635) or the dopamine D1 receptor antagonist (SCH 23,390). Moreover, co-treatment with aripiprazole (0.3 mg/kg) and escitalopram (5 mg/kg) significantly increased the levels of noradrenaline and serotonin, decreased the level of its metabolite, and did not alter level of dopamine, but decreased the levels of its metabolites. In addition, co-treatment with aripiprazole (0.3 mg/kg) and mirtazapine (10 mg/kg) significantly increased the level of noradrenaline, did not change the levels of dopamine and serotonin, but increased the levels of their metabolites. Based on these results, the increase in the extracellular levels of noradrenaline or serotonin in the cortex induced by co-treatment with an antidepressant and aripiprazole may be very important for the pharmacotherapy of negative and some cognitive symptoms of schizophrenia.
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Rogóż Z, Wąsik A, Lorenc-Koci E. Combined treatment with aripiprazole and antidepressants reversed some MK-801-induced schizophrenia-like symptoms in mice. Pharmacol Rep 2018; 70:623-630. [DOI: 10.1016/j.pharep.2018.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 02/15/2018] [Accepted: 02/22/2018] [Indexed: 02/01/2023]
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Effects of the monoamine stabilizer (−)-OSU6162 on locomotor and sensorimotor responses predictive of antipsychotic activity. Naunyn Schmiedebergs Arch Pharmacol 2018; 391:761-768. [DOI: 10.1007/s00210-018-1500-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 04/05/2018] [Indexed: 10/17/2022]
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Zink M, Correll CU. Glutamatergic agents for schizophrenia: current evidence and perspectives. Expert Rev Clin Pharmacol 2015; 8:335-52. [PMID: 25916667 DOI: 10.1586/17512433.2015.1040393] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Suboptimal outcomes in schizophrenia are a consequence of lacking insight into the etiology, biomarkers and treatment-relevant subgroups, the therapeutic restriction to dopaminergic-modulating antipsychotics that fail to significantly improve negative and cognitive symptoms, non-adherence, and, in the case of treatment-resistance, the underutilization of clozapine. Evidence suggests additional, extra-dopaminergic abnormalities in amino acid neurotransmission, particularly the glutamatergic system. Antidopaminergic antipsychotics modulate this system on several levels, as do mood stabilizers, including lamotrigine, topiramate and pregabaline. Recently, agonists at metabotropic glutamate receptors and glycine uptake inhibitors failed in large placebo-controlled trials for schizophrenia. Problems to overcome for successfully leveraging glutamatergic agents for schizophrenia are patient selection, focus on positive symptoms and late disease stages, and dose-response relationships. Because glutamate guides processes of brain development and maturation, clinical research should focus on the at-risk mental state or first-episode psychosis, address cognition and negative symptoms and use monotherapy designs in parallel to augmentation strategies.
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Affiliation(s)
- Mathias Zink
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Blockade of growth hormone secretagogue receptor 1A signaling by JMV 2959 attenuates the NMDAR antagonist, phencyclidine-induced impairments in prepulse inhibition. Psychopharmacology (Berl) 2015; 232:4285-92. [PMID: 26319159 PMCID: PMC4613889 DOI: 10.1007/s00213-015-4054-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 08/17/2015] [Indexed: 11/03/2022]
Abstract
RATIONALE Schizophrenic-spectrum patients commonly display deficits in preattentive information processing as evidenced, for example, by disrupted prepulse inhibition (PPI), a measure of sensorimotor gating. Similar disruptions in PPI can be induced in rodents and primates by the psychotomimetic drug phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor. Mounting evidence suggests that the hunger hormone ghrelin and its constitutively active receptor influences neuronal circuits involved in the regulation of mood and cognition. OBJECTIVES In the present series of experiments, we investigated the effects of ghrelin and the growth hormone secretagogue receptor (GHS-R1A) neutral antagonist, JMV 2959, on acoustic startle responses (ASR), PPI, and PCP-induced alterations in PPI. RESULTS Intraperitoneal (i.p.) administration of ghrelin (0.033, 0.1, and 0.33 mg/kg) did not alter the ASR or PPI in rats. Conversely, i.p. injection of JMV 2959 (1, 3, and 6 mg/kg), dose dependently decreased the ASR and increased PPI. Pretreatment with JMV 2959 at a dose with no effect on ASR or PPI per se, completely blocked PCP-induced (2 mg/kg) deficits in PPI while pretreatment with the highest dose of ghrelin did not potentiate or alter PPI responses of a sub-threshold dose of PCP (0.75 mg/kg). CONCLUSION These findings indicate that the GHS-R1A is involved in specific behavioral effects of PCP and may have relevance for patients with schizophrenia.
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Quinoline- and isoquinoline-sulfonamide analogs of aripiprazole: novel antipsychotic agents? Future Med Chem 2014; 6:57-75. [DOI: 10.4155/fmc.13.158] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The introduction of typical antipsychotics over six decades ago signaled an important milestone in psychiatry. However, second-generation antipsychotics ameliorated the positive symptoms of schizophrenia but displayed limited effectiveness for the negative and cognitive symptoms. In addition, while the newer antipsychotics produced fewer motor side effects, the atypical antipsychotics still induced weight gain and endocrinopathies. In recent years, a third generation of antipsychotics was identified. Aripiprazole was the first approved drug acting as a D2 partial agonist/functionally selective ligand. This review presents the state of the development of novel antipsychotic dopaminergic and non-dopaminergic agents, supported by an overview of the compounds evaluated under advanced preclinical and clinical development (e.g., cariprazine and brexpiprazole). In line with the recent trends in the development of modern atypical antipsychotics, we present our strategic development of long-chain arylpiperazine-derived quinoline- and isoquinoline-sulfonamide displaying a multireceptor binding profile and partial D2 receptor agonism.
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Subanalgesic ketamine enhances morphine-induced antinociceptive activity without cortical dysfunction in rats. J Anesth 2013; 28:390-8. [DOI: 10.1007/s00540-013-1722-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 09/20/2013] [Indexed: 12/26/2022]
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Roenker NL, Gudelsky GA, Ahlbrand R, Horn PS, Richtand NM. Evidence for involvement of nitric oxide and GABA(B) receptors in MK-801- stimulated release of glutamate in rat prefrontal cortex. Neuropharmacology 2012; 63:575-81. [PMID: 22579658 DOI: 10.1016/j.neuropharm.2012.04.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 03/23/2012] [Accepted: 04/30/2012] [Indexed: 01/18/2023]
Abstract
Systemic administration of NMDA receptor antagonists elevates extracellular glutamate within prefrontal cortex. The cognitive and behavioral effects of NMDA receptor blockade have direct relevance to symptoms of schizophrenia, and recent studies demonstrate an important role for nitric oxide and GABA(B) receptors in mediating the effects of NMDA receptor blockade on these behaviors. We sought to extend those observations by directly measuring the effects of nitric oxide and GABA(B) receptor mechanisms on MK-801-induced glutamate release in the prefrontal cortex. Systemic MK-801 injection (0.3 mg/kg) to male Sprague-Dawley rats significantly increased extracellular glutamate levels in prefrontal cortex, as determined by microdialysis. This effect was blocked by pre-treatment with the nitric oxide synthase inhibitor L-NAME (60 mg/kg). Reverse dialysis of the nitric oxide donor SNAP (0.5-5 mM) directly into prefrontal cortex mimicked the effect of systemic MK-801, dose-dependently elevating cortical extracellular glutamate. The effect of MK-801 was also blocked by systemic treatment with the GABA(B) receptor agonist baclofen (5 mg/kg). In combination, these data suggest increased nitric oxide formation is necessary for NMDA antagonist-induced elevations of extracellular glutamate in the prefrontal cortex. Additionally, the data suggest GABA(B) receptor activation can modulate the NMDA antagonist-induced increase in cortical glutamate release.
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Affiliation(s)
- Nicole L Roenker
- James Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH 45267, USA.
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Wakabayashi C, Numakawa T, Ninomiya M, Chiba S, Kunugi H. Behavioral and molecular evidence for psychotropic effects in L-theanine. Psychopharmacology (Berl) 2012; 219:1099-109. [PMID: 21861094 DOI: 10.1007/s00213-011-2440-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 08/02/2011] [Indexed: 12/24/2022]
Abstract
RATIONALE L-Theanine (N-ethyl-L: -glutamine) is an amino acid uniquely found in green tea and historically considered to be a relaxing agent. It is a glutamate derivative and has an affinity for glutamatergic receptors. However, its psychotropic effects remain unclear. OBJECTIVES To elucidate effects of L: -theanine on psychiatric disease-related behaviors in mice and its molecular basis focusing on brain-derived neurotrophic factor (BDNF) and N-methyl-D: -aspartate (NMDA) receptor. METHODS We examined the effects of L: -theanine on behaviors in mice by using the open-field test (OFT), forced swim test (FST), elevated plus-maze test (EPMT), and prepulse inhibition (PPI) of acoustic startle. By western blot analysis, we looked at the effect of L: -theanine on the expression of BDNF and related proteins in the hippocampus and cerebral cortex. To determine whether L: -theanine has agonistic action on the NMDA receptor, we performed Fluo-3 intracellular Ca(2+) imaging in cultured cortical neurons. RESULTS Single administration of L: -theanine significantly attenuated MK-801-induced deficits in PPI. Subchronic administration (3-week duration) of L: -theanine significantly reduced immobility time in the FST and improved baseline PPI. Western blotting analysis showed increased expression of BDNF protein in the hippocampus after subchronic administration of L: -theanine. In cultured cortical neurons, L: -theanine significantly increased the intracellular Ca(2+) concentration, and this increase was suppressed by competitive and non-competitive NMDA receptor antagonists (AP-5 and MK-801, respectively). CONCLUSIONS Our results suggest that L: -theanine has antipsychotic-like and possibly antidepressant-like effects. It exerts these effects, at least in part, through induction of BDNF in the hippocampus and the agonistic action of L: -theanine on the NMDA receptor.
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Affiliation(s)
- Chisato Wakabayashi
- Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1, Ogawahigashi, Kodaira, Tokyo 187-8502, Japan
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Segnitz N, Ferbert T, Schmitt A, Gass P, Gebicke-Haerter PJ, Zink M. Effects of chronic oral treatment with aripiprazole on the expression of NMDA receptor subunits and binding sites in rat brain. Psychopharmacology (Berl) 2011; 217:127-42. [PMID: 21484241 DOI: 10.1007/s00213-011-2262-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 03/13/2011] [Indexed: 12/25/2022]
Abstract
RATIONALE The glutamatergic theory of schizophrenia proposes a dysfunction of ionotropic N-methyl-D: -aspartate receptors (NMDA-R). Several therapeutic strategies address NMDA-R function and the effects of antipsychotic agents on NMDA-R expression have been described. Within the second-generation antipsychotics, the partial dopaminergic and serotonergic agonist aripiprazole (APZ) was able to counteract the behavioral effects of NMDA-R antagonists. OBJECTIVES This study aims to investigate the effects of APZ on NMDA-R subunit expression and binding. METHODS We treated Sprague-Dawley rats for 4 weeks or 4 months with APZ in daily oral doses of 10 and 40 mg per kilogram of body weight. Gene expression of the NMDA-R subunits NR1, NR2A, NR2B, NR2C, and NR2D, respectively, was assessed by semiquantitative radioactive in situ hybridization and in parallel receptor binding using (3)H-MK-801 receptor autoradiography. RESULTS Increased expression levels of NR1 (4 weeks), NR2A (4 weeks), NR2C (4 weeks and 4 months), and NR2D (4 months) were observed in several hippocampal and cortical brain regions. The parallel reduced expression of NR2B mRNAs (4 months) resulted in a relative increase of the NR2A/NR2B ratio. Marked differences between specific brain regions, the doses of APZ, and the time points of assessment became obvious. On the receptor level, increased MK-801-binding was found after 4 weeks in the 40-mg group and after 4 months in the 10-mg group. CONCLUSIONS The effects of APZ converge in enhanced NMDA receptor expression and a shift of subunit composition towards adult-type receptors. Our results confirm the regulatory connections between dopaminergic, serotonergic, and glutamatergic neurotransmissions with relevance for cognitive and negative symptoms of schizophrenia.
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Affiliation(s)
- Nina Segnitz
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, University of Heidelberg, P.O. Box 122120, 68072 Mannheim, Germany
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Flood DG, Zuvich E, Marino MJ, Gasior M. Prepulse inhibition of the startle reflex and response to antipsychotic treatments in two outbred mouse strains in comparison to the inbred DBA/2 mouse. Psychopharmacology (Berl) 2011; 215:441-54. [PMID: 21301810 DOI: 10.1007/s00213-011-2196-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Accepted: 01/19/2011] [Indexed: 12/24/2022]
Abstract
RATIONALE Naturally low prepulse inhibition (PPI) in DBA/2 mice is increased by marketed antipsychotics and compounds acting at novel targets relevant to schizophrenia. Whether other mouse strains with naturally low PPI respond similarly and could be translational models of schizophrenia is unknown. OBJECTIVE Baseline levels of PPI were determined in outbred CF-1 and Black Swiss mice. CF-1 and Black Swiss mice were then compared to DBA/2 mice for their responses to typical (haloperidol) and atypical (clozapine) antipsychotics and to compounds with potential antipsychotic activity, a histamine H(3) receptor antagonist (thioperamide) and a glycine transporter-1 inhibitor (SSR504734). RESULTS CF-1 and Black Swiss mice had naturally low PPI, similar to the level in C57BL/6 mice, but higher than that in DBA/2 mice. Haloperidol (0.3-1 mg/kg) increased PPI in DBA/2, CF-1, and Black Swiss mice. Clozapine (3 mg/kg) increased PPI in DBA/2 and CF-1 mice, but not in Black Swiss mice. Thioperamide (10-30 mg/kg) and SSR504734 (30 mg/kg) increased PPI only in DBA/2 mice. Strain differences in PPI responsiveness were not due to differences in brain concentrations of the tested compounds. CONCLUSIONS CF-1 mice with naturally low PPI may be useful for testing typical and atypical antipsychotics while Black Swiss mice only responded to a typical antipsychotic. DBA/2 mice remain the only strain with naturally low PPI that responds to marketed antipsychotics, as well as to compounds with novel mechanisms of action. Thus, DBA/2 mice may be the strain of choice for screening novel chemical entities for their ability to increase PPI.
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Affiliation(s)
- Dorothy G Flood
- EnVivo Pharmaceuticals, Inc, 480 Aresenal St, Watertown, MA 02472, USA.
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18
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Time course of the attenuation effect of repeated antipsychotic treatment on prepulse inhibition disruption induced by repeated phencyclidine treatment. Pharmacol Biochem Behav 2011; 98:559-69. [PMID: 21402097 DOI: 10.1016/j.pbb.2011.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/30/2011] [Accepted: 03/04/2011] [Indexed: 12/18/2022]
Abstract
Antagonism of prepulse inhibition (PPI) deficits produced by psychotomimetic drugs has been widely used as an effective tool for the study of the mechanisms of antipsychotic action and identifying potential antipsychotic drugs. Many studies have relied on the acute effect of a single administration of antipsychotics, whereas patients with schizophrenia are treated chronically with antipsychotic drugs. The clinical relevance of acute antipsychotic effect in this model is still an open question. In this study, we investigated the time course of repeated antipsychotic treatment on persistent PPI deficit induced by repeated phencyclidine (PCP) treatment. After a baseline test with saline, male Sprague-Dawley rats were repeatedly injected with either vehicle, haloperidol (0.05mg/kg), clozapine (5.0 or 10.0mg/kg), olanzapine (2.0mg/kg), risperidone (1.0mg/kg) or quetiapine (10mg/kg), followed by PCP (1.5mg/kg, sc) and tested for PPI once daily for 6 consecutive days. A single injection of PCP disrupted PPI and this effect was maintained with repeated PCP injections throughout the testing period. Acute clozapine, but not other antipsychotic drugs, attenuated acute PCP-induced PPI disruption at both tested doses. With repeated treatment, clozapine and quetiapine maintained their attenuation, while risperidone enhanced its effect with a significant reduction of PCP-induced disruption toward the end of treatment period. In contrast, repeated haloperidol and olanzapine treatments were ineffective. The PPI effects of these drugs were more conspicuous at a higher prepulse level (e.g. 82dB) and were dissociable from their effects on startle response and general activity. Overall, the repeated PCP-PPI model appears to be a useful model for the study of the time-dependent antipsychotic effect, and may help identify potential treatments that have a quicker onset of action than current antipsychotics.
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Kamiyama H, Matsumoto M, Otani S, Kimura SI, Shimamura KI, Ishikawa S, Yanagawa Y, Togashi H. Mechanisms underlying ketamine-induced synaptic depression in rat hippocampus-medial prefrontal cortex pathway. Neuroscience 2010; 177:159-69. [PMID: 21163337 DOI: 10.1016/j.neuroscience.2010.12.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 12/07/2010] [Accepted: 12/08/2010] [Indexed: 02/02/2023]
Abstract
The non-competitive N-methyl-D-aspartate NMDA receptor antagonist ketamine, a dissociative anesthetic capable of inducing analgesia, is known to have psychotomimetic actions, but the detailed mechanisms remain unclear because of its complex properties. The present study elucidated neural mechanisms of the effect of ketamine, at doses that exert psychotomimetic effects without anesthetic and analgesic effects, by evaluating cortical synaptic responses in vivo. Systemic administration (i.p.) of low (1 and 5 mg/kg), subanesthetic (25 mg/kg) and anesthetic (100 mg/kg) doses of ketamine dose-dependently decreased hippocampal stimulation-evoked potential in the medial prefrontal cortex (mPFC) in freely moving rats. The behavioral analysis assessed by prepulse inhibition (PPI) of acoustic startle response showed that ketamine (5 and 25 mg/kg, i.p.) produced PPI deficit. Thus, the psychotomimetic effects observed in ketamine-treated groups (5 and 25 mg/kg, i.p.) are associated with the induction of synaptic depression in the hippocampus-mPFC neural pathway. Based on these results, we further examined the underlying mechanisms of the ketamine-induced synaptic depression under anesthesia. Ketamine (5 and 25 mg/kg, i.p.) caused increases in dialysate dopamine in the mPFC in anesthetized rats. Moreover, the ketamine-induced decreases in the evoked potential, at the dose 5 mg/kg which has no anesthetic and analgesic effects, were indeed absent in dopamine-lesioned rats pretreated with 6-hydroxydopamine (6-OHDA; 150 μg/rat, i.c.v.). Ketamine (5 mg/kg, i.p.)-induced synaptic depression was blocked by pretreatment with dopamine D1 receptor antagonist SCH 23390 (10 μg/rat, i.c.v.) but not dopamine D2 receptor antagonist haloperidol (1.5 mg/kg, i.p.), suggesting that dopaminergic modulation mediated via D1 receptors are involved in the synaptic effects of ketamine. Furthermore, ketamine (5 mg/kg, i.p.)-induced synaptic depression was prevented also by GABAA receptor antagonist bicuculline (0.2 or 2 μg/rat, i.c.v.). These findings suggest that ketamine at the dose that exerts psychotomimetic symptoms depresses hippocampus-mPFC synaptic transmission through mechanisms involving dopaminergic modulation mediated via D1 receptors, which may lead to a net augmentation of synaptic inhibition mediated via GABAA receptors.
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Affiliation(s)
- H Kamiyama
- Department of Pharmacology, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, 061-0293, Japan
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Sánchez-Morla EM, Santos JL, Aparicio A, García-Jiménez MA, Villanueva C, Martínez-Vizcaíno V, Arango C. Antipsychotic effects on auditory sensory gating in schizophrenia patients. Eur Neuropsychopharmacol 2009; 19:905-9. [PMID: 19833483 DOI: 10.1016/j.euroneuro.2009.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 09/19/2009] [Accepted: 09/23/2009] [Indexed: 01/10/2023]
Abstract
P50 sensory gating deficit has repeatedly been demonstrated in schizophrenia. Studies have produced inconsistent findings with respect to normalization of P50 gating in patients with schizophrenia receiving treatment with different antipsychotics. The current study was designed to determine whether there is a difference in P50 gating in schizophrenia patients treated with first-generation antipsychotics (FGAs) and second-generation antipsychotics (SGAs), including clozapine. P50 evoked potential recordings were obtained from 160 patients with schizophrenia and 77 healthy comparison subjects. Forty-three patients were being treated with clozapine, sixty-eight were taking SGAs (33 risperidone, 21 olanzapine, 11 aripiprazole, and 3 combinations of SGAs) and 49 were being treated with FGAs. Schizophrenia patients exhibited significantly higher P50 ratios than healthy subjects. When patients treated with different antipsychotics were compared, there were no differences in any of the neurophysiological findings. Second-generation antipsychotics were not related to more normal sensory gating in this population of patients with chronic schizophrenia.
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Prefrontal GABA(B) receptor activation attenuates phencyclidine-induced impairments of prepulse inhibition: involvement of nitric oxide. Neuropsychopharmacology 2009; 34:1673-84. [PMID: 19145229 DOI: 10.1038/npp.2008.225] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent theories propose that both GABA and glutamate signaling are compromised in patients with schizophrenia. These deficits can be observed in several brain regions including the prefrontal cortex (PFC), an area extensively linked to the cognitive dysfunction in this disease and notably affected by NMDA receptor antagonists such as phencyclidine (PCP). We have previously demonstrated that inhibition of the nitric oxide (NO) pathways in the brain, particularly in the PFC, prevents a wide range of PCP-induced behavioral deficits including disruption of prepulse inhibition (PPI). This study investigated the role of GABA(B) receptor signaling and NO in the effects of PCP on PPI. Mice received systemic or prefrontal injections of the GABA(B) receptor agonist baclofen (2.5-5 mg/kg and 1 mM) before PCP treatment (5 mg/kg) and were thereafter tested for PPI. GABA/NO interactions were studied by combining baclofen and the NO synthase inhibitor L-NAME (20 mg/kg) in subthreshold doses. The role of GABA(B) receptors for NO production in vivo was assessed using NO-sensors implanted into the rat PFC. PCP-induced PPI deficits were attenuated in an additive manner by systemic baclofen treatment, whereas prefrontal microinjections of baclofen completely blocked the effects of PCP, without affecting PPI per se. The combination of baclofen and L-NAME was more effective in preventing the effects of PCP than any compound by itself. Additionally, baclofen decreased NO release in the PFC in a dose-related manner. This study proposes a role for GABA(B) receptor signaling in the effects of PCP, with altered NO levels as a downstream consequence. Thus, prefrontal NO signaling mirrors an altered level of cortical inhibition that may be of importance for information processing deficits in schizophrenia.
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Wass C, Klamer D, Fejgin K, Pålsson E. The importance of nitric oxide in social dysfunction. Behav Brain Res 2009; 200:113-6. [DOI: 10.1016/j.bbr.2009.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/28/2008] [Accepted: 01/03/2009] [Indexed: 11/29/2022]
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Nagai T, Murai R, Matsui K, Kamei H, Noda Y, Furukawa H, Nabeshima T. Aripiprazole ameliorates phencyclidine-induced impairment of recognition memory through dopamine D1 and serotonin 5-HT1A receptors. Psychopharmacology (Berl) 2009; 202:315-28. [PMID: 18679658 DOI: 10.1007/s00213-008-1240-6] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 06/13/2008] [Indexed: 12/24/2022]
Abstract
RATIONALE Cognitive deficits, including memory impairment, are regarded as a core feature of schizophrenia. Aripiprazole, an atypical antipsychotic drug, has been shown to improve disruption of prepulse inhibition and social interaction in an animal model of schizophrenia induced by phencyclidine (PCP); however, the effects of aripiprazole on recognition memory remain to be investigated. OBJECTIVES In this study, we examined the effect of aripiprazole on cognitive impairment in mice treated with PCP repeatedly. MATERIALS AND METHODS Mice were repeatedly administered PCP at a dose of 10 mg/kg for 14 days, and their cognitive function was assessed using a novel-object recognition task. We investigated the therapeutic effects of aripiprazole (0.01-1.0 mg/kg) and haloperidol (0.3 and 1.0 mg/kg) on cognitive impairment in mice treated with PCP repeatedly. RESULTS Single (1.0 mg/kg) and repeated (0.03 and 0.1 mg/kg, for 7 days) treatment with aripiprazole ameliorated PCP-induced impairment of recognition memory, although single treatment significantly decreased the total exploration time during the training session. In contrast, both single and repeated treatment with haloperidol (0.3 and 1.0 mg/kg) failed to attenuate PCP-induced cognitive impairment. The ameliorating effect of aripiprazole on recognition memory in PCP-treated mice was blocked by co-treatment with a dopamine D1 receptor antagonist, SCH23390, and a serotonin 5-HT1A receptor antagonist, WAY100635; however, co-treatment with a D2 receptor antagonist raclopride had no effect on the ameliorating effect of aripiprazole. CONCLUSIONS These results suggest that the ameliorative effect of aripiprazole on PCP-induced memory impairment is associated with dopamine D1 and serotonin 5-HT1A receptors.
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Affiliation(s)
- Taku Nagai
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Swerdlow NR, Weber M, Qu Y, Light GA, Braff DL. Realistic expectations of prepulse inhibition in translational models for schizophrenia research. Psychopharmacology (Berl) 2008; 199:331-88. [PMID: 18568339 PMCID: PMC2771731 DOI: 10.1007/s00213-008-1072-4] [Citation(s) in RCA: 415] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Accepted: 01/03/2008] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Under specific conditions, a weak lead stimulus, or "prepulse", can inhibit the startling effects of a subsequent intense abrupt stimulus. This startle-inhibiting effect of the prepulse, termed "prepulse inhibition" (PPI), is widely used in translational models to understand the biology of brainbased inhibitory mechanisms and their deficiency in neuropsychiatric disorders. In 1981, four published reports with "prepulse inhibition" as an index term were listed on Medline; over the past 5 years, new published Medline reports with "prepulse inhibition" as an index term have appeared at a rate exceeding once every 2.7 days (n=678). Most of these reports focus on the use of PPI in translational models of impaired sensorimotor gating in schizophrenia. This rapid expansion and broad application of PPI as a tool for understanding schizophrenia has, at times, outpaced critical thinking and falsifiable hypotheses about the relative strengths vs. limitations of this measure. OBJECTIVES This review enumerates the realistic expectations for PPI in translational models for schizophrenia research, and provides cautionary notes for the future applications of this important research tool. CONCLUSION In humans, PPI is not "diagnostic"; levels of PPI do not predict clinical course, specific symptoms, or individual medication responses. In preclinical studies, PPI is valuable for evaluating models or model organisms relevant to schizophrenia, "mapping" neural substrates of deficient PPI in schizophrenia, and advancing the discovery and development of novel therapeutics. Across species, PPI is a reliable, robust quantitative phenotype that is useful for probing the neurobiology and genetics of gating deficits in schizophrenia.
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Affiliation(s)
- Neal R Swerdlow
- Department of Psychiatry, UCSD School of Medicine, La Jolla, CA, 92093-0804, USA,
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Fejgin K, Pålsson E, Wass C, Svensson L, Klamer D. Nitric oxide signaling in the medial prefrontal cortex is involved in the biochemical and behavioral effects of phencyclidine. Neuropsychopharmacology 2008; 33:1874-83. [PMID: 17895915 DOI: 10.1038/sj.npp.1301587] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The prefrontal cortex (PFC) is believed to play an important role in the cognitive impairments observed in schizophrenia and has also been shown to be involved in the modulation of prepulse inhibition (PPI), a measure of preattentive information processing that is impaired in schizophrenic individuals. Phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor, exerts psychotomimetic effects in humans, disrupts PPI, and causes hypofrontality in rodents and monkeys. We have previously demonstrated that interfering with the production of nitric oxide (NO) can prevent a wide range of PCP-induced behavioral deficits, including PPI disruption. In the present study, the role of NO signaling for the behavioral and biochemical effects of PCP was further investigated. Dialysate from the medial PFC of mice receiving systemic treatment with PCP and/or the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 40 mg/kg), was analyzed for cGMP content. Furthermore, a specific inhibitor of NO-sensitive soluble guanylyl cyclase (sGC), 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ, 0.01-1 mM), was administered into the medial PFC of mice in combination with systemic injections of PCP, followed by PPI and locomotor activity testing. PCP (5 mg/kg) caused an increase in prefrontal cGMP that could be attenuated by pretreatment with the NO synthase inhibitor, L-NAME. Moreover, bilateral microinjection of the sGC inhibitor, ODQ, into the medial PFC of mice attenuated the disruption of PPI, but not the hyperlocomotion, caused by PCP. The present study shows that NO/sGC/cGMP signaling pathway in the medial PFC is involved in specific behavioral effects of PCP that may have relevance for the disabling cognitive dysfunction found in patients with schizophrenia.
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Affiliation(s)
- Kim Fejgin
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
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Effects of aripiprazole/OPC-14597 on motor activity, pharmacological models of psychosis, and brain activity in rats. Neuropharmacology 2008; 54:405-16. [DOI: 10.1016/j.neuropharm.2007.10.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 05/29/2007] [Accepted: 10/18/2007] [Indexed: 11/18/2022]
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Nitric oxide synthase inhibition attenuates phencyclidine-induced disruption of cognitive flexibility. Pharmacol Biochem Behav 2008; 89:352-9. [PMID: 18321564 DOI: 10.1016/j.pbb.2008.01.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 01/07/2008] [Accepted: 01/14/2008] [Indexed: 11/22/2022]
Abstract
Schizophrenia encompasses, amongst other symptoms, a heavy load of cognitive dysfunctionality. Using the psychotomimetic agent, phencyclidine (PCP), we have previously found that PCP-induced disruptions of cognitive function in translational rodent models of schizophrenia are dependent on nitric oxide (NO) production. In the present study, male Sprague-Dawley rats were subjected to a Morris water maze task designed to assess cognitive flexibility (i.e. the ability to cope with an increasingly demanding cognitive task) by means of a "constant reversal learning paradigm". Experiments were conducted to evaluate the effects of the NO synthase inhibitor, L-NAME (10 mg/kg), on PCP-induced (2 mg/kg) impairments. Control animals significantly improved their learning over the first 3 consecutive days, whereas PCP-treated animals failed to show any significant learning. Pretreatment with L-NAME normalized the PCP-induced disruption of learning to control levels. These findings suggest that PCP-induced disruptions of cognitive flexibility (i.e. ability to modify behaviour according to an increasingly demanding cognitive task) are dependent upon NO production. These observations, together with accumulated clinical findings, suggest that the NO system is a potential treatment target for cognitive dysfunctions in schizophrenia.
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