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Dudzik P, Lustyk K, Pytka K. Beyond dopamine: Novel strategies for schizophrenia treatment. Med Res Rev 2024; 44:2307-2330. [PMID: 38653551 DOI: 10.1002/med.22042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/02/2024] [Accepted: 04/08/2024] [Indexed: 04/25/2024]
Abstract
Despite extensive research efforts aimed at discovering novel antipsychotic compounds, a satisfactory pharmacological strategy for schizophrenia treatment remains elusive. All the currently available drugs act by modulating dopaminergic neurotransmission, leading to insufficient management of the negative and cognitive symptoms of the disorder. Due to these challenges, several attempts have been made to design agents with innovative, non-dopaminergic mechanisms of action. Consequently, a number of promising compounds are currently progressing through phases 2 and 3 of clinical trials. This review aims to examine the rationale behind the most promising of these strategies while simultaneously providing a comprehensive survey of study results. We describe the versatility behind the cholinergic neurotransmission modulation through the activation of M1 and M4 receptors, exemplified by the prospective drug candidate KarXT. Our discussion extends to the innovative approach of activating TAAR1 receptors via ulotaront, along with the promising outcomes of iclepertin, a GlyT-1 inhibitor with the potential to become the first treatment option for cognitive impairment associated with schizophrenia. Finally, we evaluate the 5-HT2A antagonist paradigm, assessing two recently developed serotonergic agents, pimavanserin and roluperidone. We present the latest advancements in developing novel solutions to the complex challenges posed by schizophrenia, offering an additional perspective on the diverse investigated drug candidates.
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Affiliation(s)
- Paulina Dudzik
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Klaudia Lustyk
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Karolina Pytka
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
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2
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Sapienza J, Agostoni G, Dall'Acqua S, Sut S, Nasini S, Martini F, Marchesi A, Bechi M, Buonocore M, Cocchi F, Cavallaro R, Spangaro M, Comai S, Bosia M. The kynurenine pathway in treatment-resistant schizophrenia at the crossroads between pathophysiology and pharmacotherapy. Schizophr Res 2024; 264:71-80. [PMID: 38101180 DOI: 10.1016/j.schres.2023.12.005] [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: 07/30/2023] [Revised: 09/28/2023] [Accepted: 12/05/2023] [Indexed: 12/17/2023]
Abstract
Two cardinal elements in the complex and multifaceted pathophysiology of schizophrenia (SCZ) are neuroinflammation and dysregulation of glutamatergic neurotransmission, with the latter being especially involved in treatment-resistant schizophrenia (TRS). Interestingly, the Kynurenine (KYN) pathway (KP) is at the crossroad between them, constituting a potential causal link and a therapeutic target. Although there is preclinical and clinical evidence indicating a dysregulation of KP associated with the clinical phenotype of SCZ, clinical studies investigating the possible relationship between changes in biomarkers of the KP and response to pharmacotherapy are still limited. Therefore, we have studied possible differences in the circulating levels of biomarkers of the metabolism of tryptophan along the KP in 43 responders to first-line treatments (FLR) and 32 TRS patients treated with clozapine, and their possible associations with psychopathology in the two subgroups. Plasma levels of KYN were significantly higher in TRS patients than in FLR patients, indicating a greater activation of KP. Furthermore, the levels of quinolinic (NMDA receptor agonist) and kynurenic acid (NMDA negative allosteric modulator) showed a negative and a positive correlation with several dimensions and the overall symptomatology in the whole sample and in FLR, but not in TRS, suggesting a putative modulating effect of clozapine elicited through the NMDA receptors. Despite the cross-sectional design of the study that prevents us from demonstrating causation, these findings show a significant relationship among circulating KP biomarkers, psychopathology, and response to pharmacotherapy in SCZ. Therefore, plasma KP biomarkers should be further investigated for developing personalized medicine approaches in SCZ.
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Affiliation(s)
- Jacopo Sapienza
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy; Department of Humanities and Life Sciences, University School for Advanced Studies IUSS, Pavia, Italy
| | - Giulia Agostoni
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Stefano Dall'Acqua
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Stefania Sut
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Sofia Nasini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
| | - Francesca Martini
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Anna Marchesi
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Margherita Bechi
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Mariachiara Buonocore
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Federica Cocchi
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Roberto Cavallaro
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy; School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Marco Spangaro
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy.
| | - Stefano Comai
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy; Division of Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy; Department of Psychiatry, McGill University, Montreal, QC, Canada; Department of Biomedical Sciences, University of Padua, Padua, Italy.
| | - Marta Bosia
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Milan, Italy; School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
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3
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Krystal JH, Kaye AP, Jefferson S, Girgenti MJ, Wilkinson ST, Sanacora G, Esterlis I. Ketamine and the neurobiology of depression: Toward next-generation rapid-acting antidepressant treatments. Proc Natl Acad Sci U S A 2023; 120:e2305772120. [PMID: 38011560 DOI: 10.1073/pnas.2305772120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023] Open
Abstract
Ketamine has emerged as a transformative and mechanistically novel pharmacotherapy for depression. Its rapid onset of action, efficacy for treatment-resistant symptoms, and protection against relapse distinguish it from prior antidepressants. Its discovery emerged from a reconceptualization of the neurobiology of depression and, in turn, insights from the elaboration of its mechanisms of action inform studies of the pathophysiology of depression and related disorders. It has been 25 y since we first presented our ketamine findings in depression. Thus, it is timely for this review to consider what we have learned from studies of ketamine and to suggest future directions for the optimization of rapid-acting antidepressant treatment.
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Affiliation(s)
- John H Krystal
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Psychiatry and Behavioral Health Services, Yale-New Haven Hospital, New Haven, CT 06510
- Clinical Neuroscience Division, National Center for Posttraumatic Stress Disorder, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516
| | - Alfred P Kaye
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Clinical Neuroscience Division, National Center for Posttraumatic Stress Disorder, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516
| | - Sarah Jefferson
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Clinical Neuroscience Division, National Center for Posttraumatic Stress Disorder, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516
| | - Matthew J Girgenti
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Clinical Neuroscience Division, National Center for Posttraumatic Stress Disorder, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516
| | - Samuel T Wilkinson
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Psychiatry and Behavioral Health Services, Yale-New Haven Hospital, New Haven, CT 06510
| | - Gerard Sanacora
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Psychiatry and Behavioral Health Services, Yale-New Haven Hospital, New Haven, CT 06510
| | - Irina Esterlis
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511
- Clinical Neuroscience Division, National Center for Posttraumatic Stress Disorder, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516
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Salvador A, Arnal LH, Vinckier F, Domenech P, Gaillard R, Wyart V. Premature commitment to uncertain decisions during human NMDA receptor hypofunction. Nat Commun 2022; 13:338. [PMID: 35039498 PMCID: PMC8763907 DOI: 10.1038/s41467-021-27876-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/21/2021] [Indexed: 11/15/2022] Open
Abstract
Making accurate decisions based on unreliable sensory evidence requires cognitive inference. Dysfunction of n-methyl-d-aspartate (NMDA) receptors impairs the integration of noisy input in theoretical models of neural circuits, but whether and how this synaptic alteration impairs human inference and confidence during uncertain decisions remains unknown. Here we use placebo-controlled infusions of ketamine to characterize the causal effect of human NMDA receptor hypofunction on cognitive inference and its neural correlates. At the behavioral level, ketamine triggers inference errors and elevated decision uncertainty. At the neural level, ketamine is associated with imbalanced coding of evidence and premature response preparation in electroencephalographic (EEG) activity. Through computational modeling of inference and confidence, we propose that this specific pattern of behavioral and neural impairments reflects an early commitment to inaccurate decisions, which aims at resolving the abnormal uncertainty generated by NMDA receptor hypofunction.
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Affiliation(s)
- Alexandre Salvador
- Laboratoire de Neurosciences Cognitives et Computationnelles, Institut National de la Santé et de la Recherche Médicale, Paris, France
- Département d'Études Cognitives, École Normale Supérieure, Université PSL, Paris, France
- Université de Paris, Paris, France
- Département de Psychiatrie, Service Hospitalo-Universitaire, GHU Paris Psychiatrie et Neurosciences, Paris, France
| | - Luc H Arnal
- Institut de l'Audition, Inserm unit 1120, Institut Pasteur, Paris, France
| | - Fabien Vinckier
- Université de Paris, Paris, France
- Département de Psychiatrie, Service Hospitalo-Universitaire, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Équipe Motivation, Cerveau et Comportement, Institut du Cerveau, Sorbonne Université, Paris, France
| | - Philippe Domenech
- Équipe Neurophysiologie des Comportements Répétitifs, Institut du Cerveau, Sorbonne Université, Paris, France
- Département Médico-Universitaire de Psychiatrie et d'Addictologie, CHU AP-HP Henri Mondor, Université Paris-Est Créteil, Créteil, France
| | - Raphaël Gaillard
- Université de Paris, Paris, France
- Département de Psychiatrie, Service Hospitalo-Universitaire, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Unité de Neuropathologie Expérimentale, Département de Santé Globale, Institut Pasteur, Paris, France
| | - Valentin Wyart
- Laboratoire de Neurosciences Cognitives et Computationnelles, Institut National de la Santé et de la Recherche Médicale, Paris, France.
- Département d'Études Cognitives, École Normale Supérieure, Université PSL, Paris, France.
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Chen ST, Hsieh CP, Lee MY, Chen LC, Huang CM, Chen HH, Chan MH. Betaine prevents and reverses the behavioral deficits and synaptic dysfunction induced by repeated ketamine exposure in mice. Biomed Pharmacother 2021; 144:112369. [PMID: 34715446 DOI: 10.1016/j.biopha.2021.112369] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/16/2022] Open
Abstract
As an N-methyl-D-aspartate (NMDA) receptor inhibitor, ketamine has become a popular recreational substance and currently is used to address treatment-resistant depression. Since heavy ketamine use is associated with persisting psychosis, cognitive impairments, and neuronal damage, the safety of ketamine treatment for depression should be concerned. The nutrient supplement betaine has been shown to counteract the acute ketamine-induced psychotomimetic effects and cognitive dysfunction through modulating NMDA receptors. This study aimed to determine whether the adjunctive or subsequent betaine treatment would improve the enduring behavioral disturbances and hippocampal synaptic abnormality induced by repeated ketamine exposure. Mice received ketamine twice daily for 14 days, either combined with betaine co-treatment or subsequent betaine post-treatment for 7 days. Thereafter, three-chamber social approach test, reciprocal social interaction, novel location/object recognition test, forced swimming test, and head-twitch response induced by serotonergic hallucinogen were monitored. Data showed that the enduring behavioral abnormalities after repeated ketamine exposure, including disrupted social behaviors, recognition memory impairments, and increased depression-like and hallucinogen-induced head-twitch responses, were remarkably improved by betaine co-treatment or post-treatment. Consistently, betaine protected and reversed the reduced hippocampal synaptic activity, such as decreases in field excitatory post-synaptic potentiation (fEPSP), long-term potentiation (LTP), and PSD-95 levels, after repeated ketamine treatment. These results demonstrated that both co-treatment and post-treatment with betaine could effectively prevent and reverse the adverse behavioral manifestations and hippocampal synaptic plasticity after repeated ketamine use, suggesting that betaine can be used as a novel adjunct therapy with ketamine for treatment-resistant depression and provide benefits for ketamine use disorders.
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Affiliation(s)
- Shao-Tsu Chen
- Department of Psychiatry, Tzu Chi University, 701, Section 3, Chung-Yang Road, Hualien, Taiwan
| | - Chung-Pin Hsieh
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Mei-Yi Lee
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Liao-Chen Chen
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Chien-Min Huang
- Animal Behavior Core National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, Taiwan
| | - Hwei-Hsien Chen
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan; Animal Behavior Core National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, Taiwan; Institute of Neuroscience, National Chengchi Uinversity, Taipei, Taiwan.
| | - Ming-Huan Chan
- Institute of Neuroscience, National Chengchi Uinversity, Taipei, Taiwan; Research Center for Mind, Brain, and Learning, National Changchi University, 64, Section 2, Zhinan Road, Taipei, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung, Taiwan.
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6
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Stone TW. Relationships and Interactions between Ionotropic Glutamate Receptors and Nicotinic Receptors in the CNS. Neuroscience 2021; 468:321-365. [PMID: 34111447 DOI: 10.1016/j.neuroscience.2021.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 02/07/2023]
Abstract
Although ionotropic glutamate receptors and nicotinic receptors for acetylcholine (ACh) have usually been studied separately, they are often co-localized and functionally inter-dependent. The objective of this review is to survey the evidence for interactions between the two receptor families and the mechanisms underlying them. These include the mutual regulation of subunit expression, which change the NMDA:AMPA response balance, and the existence of multi-functional receptor complexes which make it difficult to distinguish between individual receptor sites, especially in vivo. This is followed by analysis of the functional relationships between the receptors from work on transmitter release, cellular electrophysiology and aspects of behavior where these can contribute to understanding receptor interactions. It is clear that nicotinic receptors (nAChRs) on axonal terminals directly regulate the release of glutamate and other neurotransmitters, α7-nAChRs generally promoting release. Hence, α7-nAChR responses will be prevented not only by a nicotinic antagonist, but also by compounds blocking the indirectly activated glutamate receptors. This accounts for the apparent anticholinergic activity of some glutamate antagonists, including the endogenous antagonist kynurenic acid. The activation of presynaptic nAChRs is by the ambient levels of ACh released from pre-terminal synapses, varicosities and glial cells, acting as a 'volume neurotransmitter' on synaptic and extrasynaptic sites. In addition, ACh and glutamate are released as CNS co-transmitters, including 'cholinergic' synapses onto spinal Renshaw cells. It is concluded that ACh should be viewed primarily as a modulator of glutamatergic neurotransmission by regulating the release of glutamate presynaptically, and the location, subunit composition, subtype balance and sensitivity of glutamate receptors, and not primarily as a classical fast neurotransmitter. These conclusions and caveats should aid clarification of the sites of action of glutamate and nicotinic receptor ligands in the search for new centrally-acting drugs.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience, University of Glasgow, G12 8QQ, UK.
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7
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Qin Z, Zhang L, Zasloff MA, Stewart AFR, Chen HH. Ketamine's schizophrenia-like effects are prevented by targeting PTP1B. Neurobiol Dis 2021; 155:105397. [PMID: 34015491 DOI: 10.1016/j.nbd.2021.105397] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 04/18/2021] [Accepted: 05/14/2021] [Indexed: 11/26/2022] Open
Abstract
Subanesthetic doses of ketamine induce schizophrenia-like behaviors in mice including hyperlocomotion and deficits in working memory and sensorimotor gating. Here, we examined the effect of in vivo ketamine administration on neuronal properties and endocannabinoid (eCB)-dependent modulation of synaptic transmission onto layer 2/3 pyramidal neurons in brain slices of the prefrontal cortex, a region tied to the schizophrenia-like behavioral phenotypes of ketamine. Since deficits in working memory and sensorimotor gating are tied to activation of the tyrosine phosphatase PTP1B in glutamatergic neurons, we asked whether PTP1B contributes to these effects of ketamine. Ketamine increased membrane resistance and excitability of pyramidal neurons. Systemic pharmacological inhibition of PTP1B by Trodusquemine restored these neuronal properties and prevented each of the three main ketamine-induced behavior deficits. Ketamine also reduced mobilization of eCB by pyramidal neurons, while unexpectedly reducing their inhibitory inputs, and these effects of ketamine were blocked or occluded by PTP1B ablation in glutamatergic neurons. While ablation of PTP1B in glutamatergic neurons prevented ketamine-induced deficits in memory and sensorimotor gating, it failed to prevent hyperlocomotion (a psychosis-like phenotype). Taken together, these results suggest that PTP1B in glutamatergic neurons mediates ketamine-induced deficits in eCB mobilization, memory and sensorimotor gating whereas PTP1B in other cell types contributes to hyperlocomotion. Our study suggests that the PTP1B inhibitor Trodusquemine may represent a new class of fast-acting antipsychotic drugs to treat schizophrenia-like symptoms.
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Affiliation(s)
- Zhaohong Qin
- Ottawa Hospital Research Institute, Ottawa, ON K1H8M5, Canada
| | - Li Zhang
- Ottawa Hospital Research Institute, Ottawa, ON K1H8M5, Canada
| | - Michael A Zasloff
- Georgetown University School of Medicine, MedStar Georgetown Transplant Institute, Washington D.C. 2007, USA
| | - Alexandre F R Stewart
- University of Ottawa Heart Institute, Ottawa, ON K1Y4W7, Canada; Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
| | - Hsiao-Huei Chen
- Ottawa Hospital Research Institute, Ottawa, ON K1H8M5, Canada; Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Brain and Mind Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
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Su T, Lu Y, Geng Y, Lu W, Chen Y. How could N-Methyl-D-Aspartate Receptor Antagonists Lead to Excitation Instead of Inhibition? BRAIN SCIENCE ADVANCES 2019. [DOI: 10.26599/bsa.2018.2018.9050009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are a family of ionotropic glutamate receptors mainly known to mediate excitatory synaptic transmission and plasticity. Interestingly, low-dose NMDAR antagonists lead to increased, instead of decreased, functional connectivity; and they could cause schizophrenia- and/or antidepressant-like behavior in both humans and rodents. In addition, human genetic evidences indicate that NMDAR loss of function mutations underlie certain forms of epilepsy, a disease featured with abnormal brain hyperactivity. Together, they all suggest that under certain conditions, NMDAR activation actually lead to inhibition, but not excitation, of the global neuronal network. Apparently, these phenomena are rather counterintuitive to the receptor's basic role in mediating excitatory synaptic transmission. How could it happen? Recently, this has become a crucial question in order to fully understand the complexity of NMDAR function, particularly in disease. Over the past decades, different theories have been proposed to address this question. These include theories of “NMDARs on inhibitory neurons are more sensitive to antagonism”, or “basal NMDAR activity actually inhibits excitatory synapse”, etc. Our review summarizes these efforts, and also provides an introduction of NMDARs, inhibitory neurons, and their relationships with the related diseases. Advances in the development of novel NMDAR pharmacological tools, particularly positive allosteric modulators, are also included to provide insights into potential intervention strategies.
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Affiliation(s)
- Tonghui Su
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi Lu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Geng
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Lu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yelin Chen
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Moschetti V, Schlecker C, Wind S, Goetz S, Schmitt H, Schultz A, Liesenfeld KH, Wunderlich G, Desch M. Multiple Rising Doses of Oral BI 425809, a GlyT1 Inhibitor, in Young and Elderly Healthy Volunteers: A Randomised, Double-Blind, Phase I Study Investigating Safety and Pharmacokinetics. Clin Drug Investig 2018; 38:737-750. [PMID: 29846887 PMCID: PMC6061410 DOI: 10.1007/s40261-018-0660-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background and Objective Schizophrenia and Alzheimer’s disease are characterised by abnormalities in glutamatergic pathways related to N-methyl-d-aspartate receptor hypofunction. Glycine is an N-methyl-d-aspartate receptor co-agonist; inhibition of glycine transporter 1 may improve N-methyl-d-aspartate receptor function. This phase I, randomised, two-part study evaluated the safety, tolerability and pharmacokinetic profile of BI 425809, a novel glycine transporter 1 inhibitor, in healthy male and female volunteers. Methods Part 1 evaluated BI 425809 10, 25, 50 or 75 mg once daily or 75 mg twice daily in young subjects, and 25 mg or 50 mg once daily in elderly subjects. Each dose group comprised 12 subjects who received BI 425809 (n = 9) or placebo (n = 3) for 14 days (day 1: single dose; days 4–14: multiple dosing). Part 2 compared pharmacokinetic profiles in 12 subjects who received a single dose of BI 425809 25 mg in the morning and evening. Results Pharmacokinetic profiles were similarly shaped for all dose groups. Median time to maximum plasma concentration was 3.0–4.5 h with steady state being reached between days 6 and 10. Pharmacokinetic parameters demonstrated dose linearity at the predicted therapeutic exposure range of BI 425809 ≤ 25 mg once daily, but increased less than dose proportionally for ≥ 50 mg once daily. All reported adverse events were of mild-to-moderate intensity, 51/84 (61%; part 1) subjects had one or more treatment-related adverse event, no serious adverse events occurred and no dose dependency was observed. Conclusions Pharmacokinetic properties support both morning and evening dosing. BI 425809 was generally well tolerated at all tested doses. Clinicaltrials.gov identifier NCT02337283. Electronic supplementary material The online version of this article (10.1007/s40261-018-0660-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Sven Wind
- Boehringer Ingelheim International GmbH, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Sophia Goetz
- Boehringer Ingelheim International GmbH, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Holger Schmitt
- Boehringer Ingelheim International GmbH, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Armin Schultz
- CRS Clinical Research Services Mannheim GmbH, Mannheim, Germany
| | - Karl-Heinz Liesenfeld
- Boehringer Ingelheim International GmbH, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | | | - Michael Desch
- Boehringer Ingelheim International GmbH, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany.
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D’Souza DC, Carson RE, Driesen N, Johannesen J, Ranganathan M, Krystal JH. Dose-Related Target Occupancy and Effects on Circuitry, Behavior, and Neuroplasticity of the Glycine Transporter-1 Inhibitor PF-03463275 in Healthy and Schizophrenia Subjects. Biol Psychiatry 2018; 84:413-421. [PMID: 29499855 PMCID: PMC6068006 DOI: 10.1016/j.biopsych.2017.12.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/14/2017] [Accepted: 12/15/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Glycine transporter-1 (GlyT1) inhibitors may ameliorate cognitive impairments associated with schizophrenia. The dose-related occupancy and target engagement of the GlyT1 inhibitor PF-03463275 were studied to inform optimal dose selection for a clinical trial for cognitive impairments associated with schizophrenia. METHODS In substudy 1, the effects of PF-03463275 (10, 20, and 40 mg twice a day) on occupancy of GlyT1 were tested using positron emission tomography and 18F-MK-6577, and visual long-term potentiation (LTP) in schizophrenia patients (SZs) and healthy control subjects. Furthermore, the capacity of PF-03463275 to attenuate ketamine-induced disruption of working memory-related activation of a "working memory" circuit was tested only in healthy control subjects using functional magnetic resonance imaging. Subsequently, the effects of PF-03463275 (60 mg twice a day) on occupancy of GlyT1 and long-term potentiation were examined only in SZs (substudy 2). RESULTS PF-03463275 at 10, 20, 40, and 60 mg twice a day produced ∼44%, 61%, 76%, and 83% GlyT1 occupancy, respectively, in SZs with higher ligand binding to GlyT1 in subcortical versus cortical regions. PF-03463275 did not attenuate any ketamine-induced effects but did improve working memory accuracy in healthy control subjects. PF-03463275 increased long-term potentiation only in SZs with peak effects at 40 mg twice a day (∼75% GlyT1 occupancy) and with a profile suggestive of an inverted U dose response. PF-03463275 was well-tolerated. CONCLUSIONS The dose-related GlyT1 occupancy of PF-03463275 is linear. While PF-03463275 did not show evidence of facilitating N-methyl-D-aspartate receptor function in the ketamine assay, it enhanced neuroplasticity in SZs. These findings provide support for a clinical trial to test the ability of PF-03463275 to enhance cognitive remediation toward addressing cognitive impairments associated with schizophrenia.
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Affiliation(s)
- Deepak Cyril D’Souza
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Mental Health Service Line, VA Connecticut Healthcare System, West Haven, CT, USA,Abraham Ribicoff Research Facilities, Connecticut Mental Health Center, New Haven, CT, USA
| | - Richard E. Carson
- Yale PET Center, New Haven, CT, USA,Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA,Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Naomi Driesen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Mental Health Service Line, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Jason Johannesen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Mental Health Service Line, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Mohini Ranganathan
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Mental Health Service Line, VA Connecticut Healthcare System, West Haven, CT, USA,Abraham Ribicoff Research Facilities, Connecticut Mental Health Center, New Haven, CT, USA
| | - John H. Krystal
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Mental Health Service Line, VA Connecticut Healthcare System, West Haven, CT, USA,Abraham Ribicoff Research Facilities, Connecticut Mental Health Center, New Haven, CT, USA,Yale-New Haven Hospital, New Haven, CT,Department of Neurobiology, Yale University School of Medicine, New Haven, CT, USA
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11
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Moschetti V, Desch M, Goetz S, Liesenfeld KH, Rosenbrock H, Kammerer KP, Wunderlich G, Wind S. Safety, Tolerability and Pharmacokinetics of Oral BI 425809, a Glycine Transporter 1 Inhibitor, in Healthy Male Volunteers: A Partially Randomised, Single-Blind, Placebo-Controlled, First-in-Human Study. Eur J Drug Metab Pharmacokinet 2018; 43:239-249. [PMID: 29076028 PMCID: PMC5854750 DOI: 10.1007/s13318-017-0440-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
BACKGROUND AND OBJECTIVES Schizophrenia and Alzheimer's disease are characterised by glutamatergic pathway abnormalities related to N-methyl-D-aspartate (NMDA) receptor hypofunction and cognitive impairment. Glycine is an NMDA receptor co-agonist; inhibition of glycine transporter 1 (GlyT1) should improve NMDA receptor hypofunction. This study evaluated safety and pharmacokinetic properties of BI 425809-a potent and selective GlyT1 inhibitor. METHODS In the single-rising dose (SRD) component of this study, subjects were randomised to a single dose of BI 425809 [doses (mg): 0.5, 1, 2, 5, 10, 25, 50, 100 and 150], or placebo. The bioavailability/food effect (BA/FE) component investigated BI 425809 pharmacokinetics following single dosing (25-mg tablet) after overnight fasting or with a high-calorie meal or as solution (25 mg) after overnight fasting. RESULTS Overall, 33/83 (39.8%) subjects had ≥ 1 treatment-related adverse event (AE); there were no deaths or serious AEs. Reported SRD part AEs trended towards dose dependency, occurring at the higher doses (mostly central nervous system related). BI 425809 plasma concentration-time profiles were similarly shaped across all doses and plasma exposure increased proportional to dose. In the BA/FE component, geometric mean ratios for the area under the concentration-time curve from time zero to the last measurable concentration and the maximum plasma concentration for tablet fasted versus solution fasted were 80.5 and 50.0%, respectively, and for tablet fed versus fasted were 125.9 and 142.1%, respectively. CONCLUSION BI 425809 was generally well-tolerated at doses expected to be clinically relevant. The AE profile suggested possible GlyT1-inhibiting effects. CLINICAL TRIAL IDENTIFIER NCT02068690.
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Affiliation(s)
| | - Michael Desch
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Sophia Goetz
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | | | - Holger Rosenbrock
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | | | | | - Sven Wind
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
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12
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Abdallah CG, De Feyter HM, Averill LA, Jiang L, Averill CL, Chowdhury GMI, Purohit P, de Graaf RA, Esterlis I, Juchem C, Pittman BP, Krystal JH, Rothman DL, Sanacora G, Mason GF. The effects of ketamine on prefrontal glutamate neurotransmission in healthy and depressed subjects. Neuropsychopharmacology 2018; 43:2154-2160. [PMID: 29977074 PMCID: PMC6098048 DOI: 10.1038/s41386-018-0136-3] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 12/18/2022]
Abstract
The ability of ketamine administration to activate prefrontal glutamate neurotransmission is thought to be a key mechanism contributing to its transient psychotomimetic effects and its delayed and sustained antidepressant effects. Rodent studies employing carbon-13 magnetic resonance spectroscopy (13C MRS) methods have shown ketamine and other N-methyl-D-aspartate (NMDA) receptor antagonists to transiently increase measures reflecting glutamate-glutamine cycling and glutamate neurotransmission in the frontal cortex. However, there are not yet direct measures of glutamate neurotransmission in vivo in humans to support these hypotheses. The current first-level pilot study employed a novel prefrontal 13C MRS approach similar to that used in the rodent studies for direct measurement of ketamine effects on glutamate-glutamine cycling. Twenty-one participants (14 healthy and 7 depressed) completed two 13C MRS scans during infusion of normal saline or subanesthetic doses of ketamine. Compared to placebo, ketamine increased prefrontal glutamate-glutamine cycling, as indicated by a 13% increase in 13C glutamine enrichment (t = 2.4, p = 0.02). We found no evidence of ketamine effects on oxidative energy production, as reflected by 13C glutamate enrichment. During ketamine infusion, the ratio of 13C glutamate/glutamine enrichments, a putative measure of neurotransmission strength, was correlated with the Clinician-Administered Dissociative States Scale (r = -0.54, p = 0.048). These findings provide the most direct evidence in humans to date that ketamine increases glutamate release in the prefrontal cortex, a mechanism previously linked to schizophrenia pathophysiology and implicated in the induction of rapid antidepressant effects.
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Affiliation(s)
- Chadi G Abdallah
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA.
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA.
| | - Henk M De Feyter
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Lynnette A Averill
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Lihong Jiang
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Christopher L Averill
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Golam M I Chowdhury
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Prerana Purohit
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Robin A de Graaf
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Irina Esterlis
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Christoph Juchem
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
- Department of Radiology, Columbia University, New York, NY, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Brian P Pittman
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - John H Krystal
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Gerard Sanacora
- Clinical Neurosciences Division, National Center for PTSD, US Department of Veterans Affairs, West Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Graeme F Mason
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- Department of Radiology and Biomedical Imaging, Yale Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
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13
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Rosenbrock H, Desch M, Kleiner O, Dorner-Ciossek C, Schmid B, Keller S, Schlecker C, Moschetti V, Goetz S, Liesenfeld KH, Fillon G, Giovannini R, Ramael S, Wunderlich G, Wind S. Evaluation of Pharmacokinetics and Pharmacodynamics of BI 425809, a Novel GlyT1 Inhibitor: Translational Studies. Clin Transl Sci 2018; 11:616-623. [PMID: 30136756 PMCID: PMC6226115 DOI: 10.1111/cts.12578] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 06/14/2018] [Indexed: 01/04/2023] Open
Abstract
BI 425809 is a potent and selective glycine transporter 1 (GlyT1) inhibitor being developed for the treatment of cognitive impairment in Alzheimer disease and schizophrenia. Translational studies evaluated the effects of BI 425809 on glycine levels in rat and human cerebrospinal fluid (CSF). Oral administration of BI 425809 in rats induced a dose‐dependent increase of glycine CSF levels from 30% (0.2 mg/kg, not significant) to 78% (2 mg/kg, P < 0.01), relative to vehicle. Similarly, oral administration of BI 425809 in healthy volunteers resulted in a dose‐dependent increase in glycine CSF levels at steady state, with a mean 50% increase at doses as low as 10 mg. The peak plasma concentration (Cmax) of BI 425809 was achieved earlier in plasma than in CSF (tmax 3–5 vs. 5–8 hours, respectively). Generally, BI 425809 was safe and well tolerated. These data provide evidence of functional target engagement of GlyT1 by BI 425809.
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Affiliation(s)
- Holger Rosenbrock
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | - Michael Desch
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | - Oliver Kleiner
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | | | - Bernhard Schmid
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | - Sascha Keller
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | | | | | - Sophia Goetz
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | | | - Gwenaelle Fillon
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
| | | | | | - Glen Wunderlich
- Boehringer Ingelheim (Canada) Ltd, Burlington, Ontario, Canada
| | - Sven Wind
- Boehringer Ingelheim International GmbH, Biberach an der Riss, Germany
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14
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Santora VJ, Almos TA, Barido R, Basinger J, Bellows CL, Bookser BC, Breitenbucher JG, Broadbent NJ, Cabebe C, Chai CK, Chen M, Chow S, Chung DM, Crickard L, Danks AM, Freestone GC, Gitnick D, Gupta V, Hoffmaster C, Hudson AR, Kaplan AP, Kennedy MR, Lee D, Limberis J, Ly K, Mak CC, Masatsugu B, Morse AC, Na J, Neul D, Nikpur J, Peters M, Petroski RE, Renick J, Sebring K, Sevidal S, Tabatabaei A, Wen J, Yan Y, Yoder ZW, Zook D. Design and Synthesis of Novel and Selective Glycine Transporter-1 (GlyT1) Inhibitors with Memory Enhancing Properties. J Med Chem 2018; 61:6018-6033. [DOI: 10.1021/acs.jmedchem.8b00372] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Vincent J. Santora
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Theresa A. Almos
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Richard Barido
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jillian Basinger
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chris L. Bellows
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Brett C. Bookser
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - J. Guy Breitenbucher
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Nicola J. Broadbent
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Clifford Cabebe
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chih-Kun Chai
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Mi Chen
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Stephine Chow
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - De Michael Chung
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Lindsay Crickard
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Anne M. Danks
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Graeme C. Freestone
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Dany Gitnick
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Varsha Gupta
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Christine Hoffmaster
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Andrew R. Hudson
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Alan P. Kaplan
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Michael R. Kennedy
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Dong Lee
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - James Limberis
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Kiev Ly
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chi Ching Mak
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Brittany Masatsugu
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Andrew C. Morse
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jim Na
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - David Neul
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - John Nikpur
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Marco Peters
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Robert E. Petroski
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Joel Renick
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Kristen Sebring
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Samantha Sevidal
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Ali Tabatabaei
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jenny Wen
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Yingzhuo Yan
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Zachary W. Yoder
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Douglas Zook
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
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15
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Affiliation(s)
- Christopher L. Cioffi
- Departments of Basic and Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences , Albany, NY, USA
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16
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Javitt DC, Carter CS, Krystal JH, Kantrowitz JT, Girgis RR, Kegeles LS, Ragland JD, Maddock RJ, Lesh TA, Tanase C, Corlett PR, Rothman DL, Mason G, Qiu M, Robinson J, Potter WZ, Carlson M, Wall MM, Choo TH, Grinband J, Lieberman JA. Utility of Imaging-Based Biomarkers for Glutamate-Targeted Drug Development in Psychotic Disorders: A Randomized Clinical Trial. JAMA Psychiatry 2018; 75:11-19. [PMID: 29167877 PMCID: PMC5833531 DOI: 10.1001/jamapsychiatry.2017.3572] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
IMPORTANCE Despite strong theoretical rationale and preclinical evidence, several glutamate-targeted treatments for schizophrenia have failed in recent pivotal trials, prompting questions as to target validity, compound inadequacy, or lack of target engagement. A key limitation for glutamate-based treatment development is the lack of functional target-engagement biomarkers for translation between preclinical and early-stage clinical studies. We evaluated the utility of 3 potential biomarkers-ketamine-evoked changes in the functional magnetic imaging (fMRI) blood oxygen level-dependent response (pharmacoBOLD), glutamate proton magnetic resonance spectroscopy (1H MRS), and task-based fMRI-for detecting ketamine-related alterations in brain glutamate. OBJECTIVE To identify measures with sufficient effect size and cross-site reliability to serve as glutamatergic target engagement biomarkers within early-phase clinical studies. DESIGN, SETTING, AND PARTICIPANTS This randomized clinical trial was conducted at an academic research institution between May 2014 and October 2015 as part of the National Institute of Mental Health-funded Fast-Fail Trial for Psychotic Spectrum Disorders project. All raters were blinded to study group. Healthy volunteers aged 18 to 55 years of either sex and free of significant medical or psychiatric history were recruited from 3 sites. Data were analyzed between November 2015 and December 2016. INTERVENTIONS Volunteers received either sequential ketamine (0.23 mg/kg infusion over 1 minute followed by 0.58 mg/kg/h infusion over 30 minutes and then 0.29 mg/kg/h infusion over 29 minutes) or placebo infusions. MAIN OUTCOMES AND MEASURES Ketamine-induced changes in pharmacoBOLD, 1H MRS, and task-based fMRI measures, along with symptom ratings. Measures were prespecified prior to data collection. RESULTS Of the 65 volunteers, 41 (63%) were male, and the mean (SD) age was 31.1 (9.6) years; 59 (91%) had at least 1 valid scan. A total of 53 volunteers (82%) completed both ketamine infusions. In pharmacoBOLD, a highly robust increase (Cohen d = 5.4; P < .001) in fMRI response was observed, with a consistent response across sites. A smaller but significant signal (Cohen d = 0.64; P = .04) was also observed in 1H MRS-determined levels of glutamate+glutamine immediately following ketamine infusion. By contrast, no significant differences in task-activated fMRI responses were found between groups. CONCLUSIONS AND RELEVANCE These findings demonstrate robust effects of ketamine on pharmacoBOLD across sites, supporting its utility for definitive assessment of functional target engagement. Other measures, while sensitive to ketamine effects, were not sufficiently robust for use as cross-site target engagement measures. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT02134951.
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Affiliation(s)
- Daniel C. Javitt
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York,Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, New York
| | | | - John H. Krystal
- Department of Psychiatry, Yale University, New Haven, Connecticut
| | - Joshua T. Kantrowitz
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York,Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, New York
| | - Ragy R. Girgis
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
| | - Lawrence S. Kegeles
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
| | | | | | - Tyler A. Lesh
- Department of Psychiatry, University of California, Davis
| | - Costin Tanase
- Department of Psychiatry, University of California, Davis
| | | | | | - Graeme Mason
- Department of Psychiatry, Yale University, New Haven, Connecticut
| | - Maolin Qiu
- Department of Psychiatry, Yale University, New Haven, Connecticut
| | - James Robinson
- Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, New York
| | | | - Marlene Carlson
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
| | - Melanie M. Wall
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York,National Institute of Mental Health, Rockville, Maryland
| | - Tse-Hwei Choo
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
| | - Jack Grinband
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
| | - Jeffrey A. Lieberman
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, New York
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17
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Attenuation of ketamine-induced impairment in verbal learning and memory in healthy volunteers by the AMPA receptor potentiator PF-04958242. Mol Psychiatry 2017; 22:1633-1640. [PMID: 28242871 DOI: 10.1038/mp.2017.6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/22/2016] [Accepted: 12/19/2016] [Indexed: 01/03/2023]
Abstract
There is a need to develop treatments for cognitive impairment associated with schizophrenia (CIAS). The significant role played by N-methyl-d-aspartate receptors (NMDARs) in both the pathophysiology of schizophrenia and in neuronal plasticity suggests that facilitation of NMDAR function might ameliorate CIAS. One strategy to correct NMDAR hypofunction is to stimulate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as AMPAR and NMDAR functioning are coupled and interdependent. In rats and nonhuman primates (NHP), AMPAR potentiators reduce spatial working memory deficits caused by the nonselective NMDAR antagonist ketamine. The current study assessed whether the AMPAR potentiator PF-04958242 would attenuate ketamine-induced deficits in verbal learning and memory in humans. Healthy male subjects (n=29) participated in two randomized treatment periods of daily placebo or PF-04958242 for 5 days separated by a washout period. On day 5 of each treatment period, subjects underwent a ketamine infusion for 75 min during which the effects of PF-04958242/placebo were assessed on ketamine-induced: (1) impairments in verbal learning and recall measured by the Hopkins Verbal Learning Test; (2) impairments in working memory on a CogState battery; and (3) psychotomimetic effects measured by the Positive and Negative Syndrome Scale and Clinician-Administered Dissociative Symptoms Scale. PF-04958242 significantly reduced ketamine-induced impairments in immediate recall and the 2-Back and spatial working memory tasks (CogState Battery), without significantly attenuating ketamine-induced psychotomimetic effects. There were no pharmacokinetic interactions between PF-04958242 and ketamine. Furthermore, PF-04958242 was well tolerated. 'High-impact' AMPAR potentiators like PF-04958242 may have a role in the treatment of the cognitive symptoms, but not the positive or negative symptoms, associated with schizophrenia. The excellent concordance between the preclinical (rat, NHP) and human studies with PF-04958242, and in silico modeling of AMPAR-NMDAR interactions in the hippocampus, highlights the translational value of this study.
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Dauvermann MR, Lee G, Dawson N. Glutamatergic regulation of cognition and functional brain connectivity: insights from pharmacological, genetic and translational schizophrenia research. Br J Pharmacol 2017. [PMID: 28626937 DOI: 10.1111/bph.13919] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The pharmacological modulation of glutamatergic neurotransmission to improve cognitive function has been a focus of intensive research, particularly in relation to the cognitive deficits seen in schizophrenia. Despite this effort, there has been little success in the clinical use of glutamatergic compounds as procognitive drugs. Here, we review a selection of the drugs used to modulate glutamatergic signalling and how they impact on cognitive function in rodents and humans. We highlight how glutamatergic dysfunction, and NMDA receptor hypofunction in particular, is a key mechanism contributing to the cognitive deficits observed in schizophrenia and outline some of the glutamatergic targets that have been tested as putative procognitive targets for this disorder. Using translational research in this area as a leading exemplar, namely, models of NMDA receptor hypofunction, we discuss how the study of functional brain network connectivity can provide new insight into how the glutamatergic system impacts on cognitive function. Future studies characterizing functional brain network connectivity will increase our understanding of how glutamatergic compounds regulate cognition and could contribute to the future success of glutamatergic drug validation. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.
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Affiliation(s)
- Maria R Dauvermann
- School of Psychology, National University of Ireland, Galway, Ireland.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Graham Lee
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Neil Dawson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
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Thiebes S, Leicht G, Curic S, Steinmann S, Polomac N, Andreou C, Eichler I, Eichler L, Zöllner C, Gallinat J, Hanganu-Opatz I, Mulert C. Glutamatergic deficit and schizophrenia-like negative symptoms: new evidence from ketamine-induced mismatch negativity alterations in healthy male humans. J Psychiatry Neurosci 2017; 42:273-283. [PMID: 28556775 PMCID: PMC5487274 DOI: 10.1503/jpn.160187] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Targeting the N-methyl-D-aspartate receptor (NMDAR) is a major translational approach for treating negative symptoms of schizophrenia. Ketamine comprehensively produces schizophrenia-like symptoms, such as positive, cognitive and negative symptoms in healthy volunteers. The amplitude of the mismatch negativity (MMN) is known to be significantly reduced not only in patients with schizophrenia, but also in healthy controls receiving ketamine. Accordingly, it was the aim of the present study to investigate whether changes of MMN amplitudes during ketamine administration are associated with the emergence of schizophrenia-like negative symptoms in healthy volunteers. METHODS We examined the impact of ketamine during an MMN paradigm with 64-channel electroencephalography (EEG) and assessed the psychopathological status using the Positive and Negative Syndrome Scale (PANSS) in healthy male volunteers using a single-blind, randomized, placebo-controlled crossover design. Low-resolution brain electromagnetic tomography was used for source localization. RESULTS Twenty-four men were included in our analysis. Significant reductions of MMN amplitudes and an increase in all PANSS scores were identified under the ketamine condition. Smaller MMN amplitudes were specifically associated with more pronounced negative symptoms. Source analysis of MMN generators indicated a significantly reduced current source density (CSD) under the ketamine condition in the primary auditory cortex, the posterior cingulate and the middle frontal gyrus. LIMITATIONS The sample included only men within a tight age range of 20-32 years. CONCLUSION The MMN might represent a biomarker for negative symptoms in schizophrenia related to an insufficient NMDAR system and could be used to identify patients with schizophrenia with negative symptoms due to NMDAR dysfunction.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Christoph Mulert
- Correspondence to: C. Mulert, Martinistr. 52, D-20246 Hamburg, Germany;
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Spiros A, Roberts P, Geerts H. Semi-mechanistic computer simulation of psychotic symptoms in schizophrenia with a model of a humanized cortico-striatal-thalamocortical loop. Eur Neuropsychopharmacol 2017; 27:107-119. [PMID: 28062203 DOI: 10.1016/j.euroneuro.2016.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 11/20/2016] [Accepted: 12/24/2016] [Indexed: 12/13/2022]
Abstract
Despite new insights into the pathophysiology of schizophrenia and clinical trials with highly selective drugs, no new therapeutic breakthroughs have been identified. We present a semi-mechanistic Quantitative Systems Pharmacology (QSP) computer model of a biophysically realistic cortical-striatal-thalamo-cortical loop. The model incorporates the direct, indirect and hyperdirect pathway of the basal ganglia and CNS drug targets that modulate neuronal firing, based on preclinical data about their localization and coupling to voltage-gated ion channels. Schizophrenia pathology is introduced using quantitative human imaging data on striatal hyperdopaminergic activity and cortical dysfunction. We identified an entropy measure of neuronal firing in the thalamus, related to the bandwidth of information processing that correlates well with reported historical clinical changes on PANSS Total with antipsychotics after introduction of their pharmacology (42 drug-dose combinations, r2=0.62). This entropy measure is further validated by predicting the clinical outcome of 28 other novel stand-alone interventions, 14 of them with non-dopamine D2R pharmacology, in addition to 8 augmentation trials (correlation between actual and predicted clinical scores r2=0.61). The platform predicts that most combinations of antipsychotics have a lower efficacy over what can be achieved by either one; negative pharmacodynamical interactions are prominent for aripiprazole added to risperidone, haloperidol, quetiapine and paliperidone. The model also recapitulates the increased probability for psychotic breakdown in a supersensitive environment and the effect of ketamine in healthy volunteers. This QSP platform, combined with similar readouts for motor symptoms, negative symptoms and cognitive impairment has the potential to improve our understanding of drug effects in schizophrenia patients.
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Affiliation(s)
- Athan Spiros
- In Silico Biosciences, Berwyn, PA, United States
| | - Patrick Roberts
- In Silico Biosciences, Berwyn, PA, United States; Washington State University, Vancouver, WA, United States
| | - Hugo Geerts
- In Silico Biosciences, Berwyn, PA, United States; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
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21
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Schmidt RW, Thompson ML. Glycinergic signaling in the human nervous system: An overview of therapeutic drug targets and clinical effects. Ment Health Clin 2016; 6:266-276. [PMID: 29955481 PMCID: PMC6007534 DOI: 10.9740/mhc.2016.11.266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Glycine and related endogenous compounds (d-serine, d-alanine, sarcosine) serve critical roles in both excitatory and inhibitory neurotransmission and are influenced by a multitude of enzymes and transporters, including glycine transporter 1 and 2 (GlyT1 and GlyT2), d-amino acid oxidase (DAAO), serine racemase (SRR), alanine-serine-cysteine transporter 1 (Asc-1), and kynurenine aminotransferase (KAT). MEDLINE, Web of Science, and PsychINFO were searched for relevant human trials of compounds. Many studies utilizing exogenous administration of small molecule agonists of the glycineB site of n-methyl-d-aspartate receptor have been studied as have a growing number of glycine transporter type 1 (GlyT1) inhibitors. The clinical effects of these compounds are reviewed as are the potential effects of newer novel compounds.
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Affiliation(s)
- Robert W Schmidt
- Clinical Pharmacy Specialist, Mental Health, Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Virginia,
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de la Salle S, Choueiry J, Shah D, Bowers H, McIntosh J, Ilivitsky V, Knott V. Effects of Ketamine on Resting-State EEG Activity and Their Relationship to Perceptual/Dissociative Symptoms in Healthy Humans. Front Pharmacol 2016; 7:348. [PMID: 27729865 PMCID: PMC5037139 DOI: 10.3389/fphar.2016.00348] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/15/2016] [Indexed: 11/13/2022] Open
Abstract
N-methyl-D-aspartate (NMDA) receptor antagonists administered to healthy humans results in schizophrenia-like symptoms, which preclinical research suggests are due to glutamatergically altered brain oscillations. Here, we examined resting-state electroencephalographic activity in 21 healthy volunteers assessed in a placebo-controlled, double-blind, randomized study involving administration of either a saline infusion or a sub-anesthetic dose of ketamine, an NMDA receptor antagonist. Frequency-specific current source density (CSD) was assessed at sensor-level and source-level using eLORETA within regions of interest of a triple network model of schizophrenia (this model posits a dysfunctional switching between large-scale Default Mode and Central Executive networks by the monitor-controlling Salience Network). These CSDs were measured in each session along with subjective symptoms as indexed with the Clinician Administered Dissociative States Scale. Ketamine-induced CSD reductions in slow (delta/theta and alpha) and increases in fast (gamma) frequencies at scalp electrode sites were paralleled by frequency-specific CSD changes in the Default Mode, Central Executive, and Salience networks. Subjective symptoms scores were increased with ketamine and ratings of depersonalization in particular were associated with alpha CSD reductions in general and in specific regions of interest in each of the three networks. These results tentatively support the hypothesis that pathological brain oscillations associated with hypofunctional NMDA receptor activity may contribute to the emergence of the perceptual/dissociate symptoms of schizophrenia.
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Affiliation(s)
| | - Joelle Choueiry
- Department of Cellular and Molecular Medicine, University of Ottawa Ottawa, ON, Canada
| | - Dhrasti Shah
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Hayley Bowers
- Department of Psychology, University of Guelph Guelph, ON, Canada
| | - Judy McIntosh
- University of Ottawa Institute of Mental Health Research Ottawa, ON, Canada
| | - Vadim Ilivitsky
- Department of Psychiatry, University of OttawaOttawa, ON, Canada; Royal Ottawa Mental Health CentreOttawa, ON, Canada
| | - Verner Knott
- School of Psychology, University of OttawaOttawa, ON, Canada; Department of Cellular and Molecular Medicine, University of OttawaOttawa, ON, Canada; University of Ottawa Institute of Mental Health ResearchOttawa, ON, Canada; Department of Psychiatry, University of OttawaOttawa, ON, Canada
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23
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van de Kerkhof NW, Fekkes D, van der Heijden FM, Hoogendijk WJ, Stöber G, Egger JI, Verhoeven WM. Cycloid psychoses in the psychosis spectrum: evidence for biochemical differences with schizophrenia. Neuropsychiatr Dis Treat 2016; 12:1927-33. [PMID: 27536115 PMCID: PMC4977096 DOI: 10.2147/ndt.s101317] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cycloid psychoses (CP) differ from schizophrenia regarding symptom profile, course, and prognosis and over many decades they were thought to be a separate entity within the psychosis spectrum. As to schizophrenia, research into the pathophysiology has focused on dopamine, brain-derived neurotrophic factor, and glutamate signaling in which, concerning the latter, the N-methyl-d-aspartate receptor plays a crucial role. The present study aims to determine whether CP can biochemically be delineated from schizophrenia. Eighty patients referred for psychotic disorders were assessed with the Comprehensive Assessment of Symptoms and History, and (both at inclusion and after 6 weeks of antipsychotic treatment) with the Positive and Negative Syndrome Scale and Clinical Global Impression. From 58 completers, 33 patients were diagnosed with schizophrenia and ten with CP according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and Leonhard criteria, respectively. Fifteen patients were diagnosed with other disorders within the psychosis spectrum. At both time points, blood levels of the dopamine metabolite homovanillic acid, brain-derived neurotrophic factor, and amino acids related to glutamate neurotransmission were measured and compared with a matched control sample. Patients with CP showed a significantly better response to antipsychotic treatment as compared to patients with schizophrenia. In CP, glycine levels were elevated and tryptophan levels were lowered as compared to schizophrenia. Glutamate levels were increased in both patient groups as compared to controls. These results, showing marked differences in both treatment outcome and glutamate-related variable parameters, may point at better neuroplasticity in CP, necessitating demarcation of this subgroup within the psychosis spectrum.
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Affiliation(s)
- Nora Wa van de Kerkhof
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Department of Psychiatry
| | - Durk Fekkes
- Department of Psychiatry; Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | | | - Gerald Stöber
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Jos Im Egger
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Behavioural Science Institute; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Willem Ma Verhoeven
- Vincent van Gogh Institute for Psychiatry, Centre of Excellence for Neuropsychiatry, Venray; Department of Psychiatry
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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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Brown MA, Bishnoi RJ, Dholakia S, Velligan DI. Methodological issues associated with preclinical drug development and increased placebo effects in schizophrenia clinical trials. Expert Rev Clin Pharmacol 2015; 9:591-604. [PMID: 26696325 DOI: 10.1586/17512433.2016.1135734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent failures to detect efficacy in clinical trials investigating pharmacological treatments for schizophrenia raise concerns regarding the potential contribution of methodological shortcomings to this research. This review provides an examination of two key methodological issues currently suspected of playing a role in hampering schizophrenia drug development; 1) limitations on the translational utility of preclinical development models, and 2) methodological challenges posed by increased placebo effects. Recommendations for strategies to address these methodological issues are addressed.
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Affiliation(s)
- Matt A Brown
- a Department of Psychiatry , University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Ram J Bishnoi
- a Department of Psychiatry , University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Sara Dholakia
- a Department of Psychiatry , University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Dawn I Velligan
- a Department of Psychiatry , University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
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Ketamine-Induced Changes in the Signal and Noise of Rule Representation in Working Memory by Lateral Prefrontal Neurons. J Neurosci 2015; 35:11612-22. [PMID: 26290238 DOI: 10.1523/jneurosci.1839-15.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Working memory dysfunction is an especially debilitating symptom in schizophrenia. The NMDA antagonist ketamine has been successfully used to model working memory deficits in both rodents and nonhuman primates, but how it affects the strength and the consistency of working memory representations remains unclear. Here we recorded single-neuron activity in the lateral prefrontal cortex of macaque monkeys before and after the administration of subanesthetic doses of ketamine in a rule-based working memory task. The rule was instructed with a color cue before each delay period and dictated the correct prosaccadic or antisaccadic response to a peripheral stimulus appearing after the delay. We found that acute ketamine injections both weakened the rule signal across all delay periods and amplified the trial-to-trial variance in neural activities (i.e., noise), both within individual neurons and at the ensemble level, resulting in impaired performance. In the minority of postinjection trials when the animals responded correctly, the preservation of the signal strength during the delay periods was predictive of their subsequent success. Our findings suggest that NMDA receptor function may be critical for establishing the optimal signal-to-noise ratio in information representation by ensembles of prefrontal cortex neurons. SIGNIFICANCE STATEMENT In schizophrenia patients, working memory deficit is highly debilitating and currently without any efficacious treatment. An improved understanding of the pathophysiology of this symptom may provide critical information to treatment development. The NMDA antagonist ketamine, when injected at a subanesthetic dose, produces working memory deficit and other schizophrenia-like symptoms in humans and other animals. Here we investigated the effects of ketamine on the representation of abstract rules by prefrontal neurons, while macaque monkeys held the rules in working memory before responding accordingly. We found that ketamine weakened the signal-to-noise ratio in rule representation by simultaneously weakening the signal and augmenting noise. Both processes may be relevant in an effective therapy for working memory impairment in schizophrenia.
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27
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Grimm O, Gass N, Weber-Fahr W, Sartorius A, Schenker E, Spedding M, Risterucci C, Schweiger JI, Böhringer A, Zang Z, Tost H, Schwarz AJ, Meyer-Lindenberg A. Acute ketamine challenge increases resting state prefrontal-hippocampal connectivity in both humans and rats. Psychopharmacology (Berl) 2015; 232:4231-41. [PMID: 26184011 DOI: 10.1007/s00213-015-4022-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 07/06/2015] [Indexed: 12/27/2022]
Abstract
RATIONALE Aberrant prefrontal-hippocampal (PFC-HC) connectivity is disrupted in several psychiatric and at-risk conditions. Advances in rodent functional imaging have opened the possibility that this phenotype could serve as a translational imaging marker for psychiatric research. Recent evidence from functional magnetic resonance imaging (fMRI) studies has indicated an increase in PFC-HC coupling during working-memory tasks in both schizophrenic patients and at-risk populations, in contrast to a decrease in resting-state PFC-HC connectivity. Acute ketamine challenge is widely used in both humans and rats as a pharmacological model to study the mechanisms of N-methyl-D-aspartate (NMDA) receptor hypofunction in the context of psychiatric disorders. OBJECTIVES We aimed to establish whether acute ketamine challenge has consistent effects in rats and humans by investigating resting-state fMRI PFC-HC connectivity and thus to corroborate its potential utility as a translational probe. METHODS Twenty-four healthy human subjects (12 females, mean age 25 years) received intravenous doses of either saline (placebo) or ketamine (0.5 mg/kg body weight). Eighteen Sprague-Dawley male rats received either saline or ketamine (25 mg/kg). Resting-state fMRI measurements took place after injections, and the data were analyzed for PFC-HC functional connectivity. RESULTS In both species, ketamine induced a robust increase in PFC-HC coupling, in contrast to findings in chronic schizophrenia. CONCLUSIONS This translational comparison demonstrates a cross-species consistency in pharmacological effect and elucidates ketamine-induced alterations in PFC-HC coupling, a phenotype often disrupted in pathological conditions, which may give clue to understanding of psychiatric disorders and their onset, and help in the development of new treatments.
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Affiliation(s)
- Oliver Grimm
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Natalia Gass
- Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany.
| | - Wolfgang Weber-Fahr
- Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Alexander Sartorius
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany.,Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Esther Schenker
- Neuroscience Drug Discovery Unit, Institut de Recherches Servier, Croissy s/Seine, France
| | | | - Celine Risterucci
- CNS Biomarker, Pharmaceuticals Division, F. Hoffmann-La Roche, Basel, Switzerland
| | - Janina Isabel Schweiger
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Andreas Böhringer
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Zhenxiang Zang
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Heike Tost
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
| | - Adam James Schwarz
- Tailored Therapeutics, Eli Lilly and Company, Indianapolis, IN, USA.,Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA.,Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, USA
| | - Andreas Meyer-Lindenberg
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, J5, 68159, Mannheim, Germany
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Popik P, Holuj M, Nikiforuk A, Kos T, Trullas R, Skolnick P. 1-aminocyclopropanecarboxylic acid (ACPC) produces procognitive but not antipsychotic-like effects in rats. Psychopharmacology (Berl) 2015; 232:1025-38. [PMID: 25260339 PMCID: PMC4336651 DOI: 10.1007/s00213-014-3738-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/29/2014] [Indexed: 12/31/2022]
Abstract
RATIONALE In addition to the negative and positive symptoms of schizophrenia, cognitive deficits, including prefrontal cortical dysfunction, are now recognized as core features of this disorder. Compounds increasing the NMDA receptor function via the strychnine-insensitive glycine receptors have been proposed as potential antipsychotics. Depending on the ambient concentrations of glutamate and glycine, 1-aminocyclopropanecarboxylic acid (ACPC) behaves as either a partial agonist or a functional antagonist at the strychnine-insensitive glycine receptors. OBJECTIVES We investigated the procognitive and antipsychotic-like effects of ACPC in rats treated with phencyclidine (PCP) or ketamine (KET), compounds that produce psychotic-like symptoms in humans and laboratory animals. METHODS Cognitive effects were investigated in the novel object recognition (NOR) and attentional set-shifting tests (ASST). In addition, the effects of ACPC were investigated in PCP-induced hyperactivity, conditioned avoidance response (CAR), and prepulse inhibition (PPI) tests. The effects on attention and impulsivity were measured in the five-choice serial reaction time task (5-CSRTT). RESULTS ACPC (200-400 mg/kg) inhibited memory fading in naive rats and like clozapine prevented PCP- and KET-induced amnesia in the NOR. In naive animals, ACPC at 400 but not 200 mg/kg enhanced cognitive flexibility in the ASST, as the animals required fewer trials to reach the criteria during the extra-dimensional phase. In contrast, ACPC did not affect PCP-induced hyperactivity, CAR, and PPI as well as attention and impulsivity in the 5-CSRTT. CONCLUSION The present study demonstrates that ACPC enhanced both object recognition memory and cognitive flexibility dependent on the prefrontal cortex, but did not affect impulsivity nor exhibit an antipsychotic-like profile.
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Affiliation(s)
- Piotr Popik
- Behavioral Neuroscience and Drug Development, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Kraków, Poland,
| | - Malgorzata Holuj
- Behavioral Neuroscience and Drug Development, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Kraków, Poland
| | - Agnieszka Nikiforuk
- Behavioral Neuroscience and Drug Development, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Kraków, Poland
| | - Tomasz Kos
- Behavioral Neuroscience and Drug Development, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Kraków, Poland
| | - Ramon Trullas
- Institut d’Investigacions Biomèdiques August Pi i Sunyer, IDIBAPS-CSIC, 08036 Barcelona, Spain
| | - Phil Skolnick
- Division of Pharmacotherapies & Medical Consequences of Drug Abuse, NIDA, NIH, Bethesda, MD 20892-9551 USA
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Castner SA, Murthy NV, Ridler K, Herdon H, Roberts BM, Weinzimmer DP, Huang Y, Zheng MQ, Rabiner EA, Gunn RN, Carson RE, Williams GV, Laruelle M. Relationship between glycine transporter 1 inhibition as measured with positron emission tomography and changes in cognitive performances in nonhuman primates. Neuropsychopharmacology 2014; 39:2742-9. [PMID: 24487737 PMCID: PMC4200505 DOI: 10.1038/npp.2014.4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 11/04/2013] [Accepted: 12/13/2013] [Indexed: 01/22/2023]
Abstract
Several lines of evidence suggest that schizophrenia is associated with deficits in glutamatergic transmission at the N-methyl-d-aspartate (NMDA) receptors. Glycine is a NMDA receptor co-agonist, and extracellular levels of glycine are regulated in the forebrain by the glycine type-1 transporters (GlyT-1). GlyT-1 inhibitors elevate extracellular glycine and thus potentiate NMDA transmission. This mechanism represents a promising new avenue for the treatment of schizophrenia. Here, the recently introduced positron emission tomography radiotracer [11C]GSK931145 was used to quantify the relationship between occupancy of GlyT-1 by a GlyT-1 inhibitor, Org 25935, and its impact on spatial working memory performances in rhesus monkeys. The effect of Org 25935 on working memory was assessed both in control conditions and during a state of relative NMDA hypofunction induced by ketamine administration, at a dose selected for each animal to reduce task performance by about 50%. Under control conditions, Org 25935 had no effect on working memory at GlyT-1 occupancies lower than 75% and significantly impaired working memory at occupancies higher than 75%. Under ketamine conditions, Org 25935 reversed the deficit in working memory induced by ketamine and did so optimally in the 40-70% GlyT-1 occupancy range. The results confirm the efficacy of this mechanism to correct working memory deficits associated with NMDA hypofunction. These data also suggest the existence of an inverted-U dose-response curve in the potential therapeutic effect of this class of compounds.
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Affiliation(s)
- S A Castner
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - N V Murthy
- Neurosciences Centre for Excellence in Drug Discovery, GlaxoSmithKline, Harlow, UK
| | - K Ridler
- Clinical Imaging Centre, GlaxoSmithKline, Hammersmith Hospital–Imperial College, London, UK
| | - H Herdon
- Neurosciences Centre for Excellence in Drug Discovery, GlaxoSmithKline, Harlow, UK
| | - B M Roberts
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - D P Weinzimmer
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Y Huang
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - M Q Zheng
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - E A Rabiner
- Clinical Imaging Centre, GlaxoSmithKline, Hammersmith Hospital–Imperial College, London, UK
| | - R N Gunn
- Clinical Imaging Centre, GlaxoSmithKline, Hammersmith Hospital–Imperial College, London, UK
| | - R E Carson
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - G V Williams
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - M Laruelle
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA,Neurosciences Centre for Excellence in Drug Discovery, GlaxoSmithKline, Harlow, UK,Department of Radiology, Yale University School of Medicine, New Haven, CT, USA,UCB Pharma, Braine-l'Alleud, Brussels, Belgium,UCB Pharma, Chemin du Foriest, Braine-l'Alleud 1420, Belgium, Tel: +1 914 316 0923, Fax: +322 386 2550, E-mail:
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30
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Antipsychotic treatment modulates glutamate transport and NMDA receptor expression. Eur Arch Psychiatry Clin Neurosci 2014; 264 Suppl 1:S67-82. [PMID: 25214389 DOI: 10.1007/s00406-014-0534-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/02/2014] [Indexed: 12/21/2022]
Abstract
Schizophrenia patients often suffer from treatment-resistant cognitive and negative symptoms, both of which are influenced by glutamate neurotransmission. Innovative therapeutic strategies such as agonists at metabotropic glutamate receptors or glycin reuptake inhibitors try to modulate the brain's glutamate network. Interactions of amino acids with monoamines have been described on several levels, and first- and second-generation antipsychotic agents (FGAs, SGAs) are known to exert modulatory effects on the glutamatergic system. This review summarizes the current knowledge on effects of FGAs and SGAs on glutamate transport and receptor expression derived from pharmacological studies. Such studies serve as a control for molecular findings in schizophrenia brain tissue and are clinically relevant. Moreover, they may validate animal models for psychosis, foster basic research on antipsychotic substances and finally lead to a better understanding of how monoaminergic and amino acid neurotransmissions are intertwined. In the light of these results, important differences dependent on antipsychotic substances, dosage and duration of treatment became obvious. While some post-mortem findings might be confounded with multifold drug effects, others are unlikely to be influenced by antipsychotic treatment and could represent important markers of schizophrenia pathophysiology. In similarity to the convergence of toxic and psychotomimetic effects of dopaminergic, serotonergic and anti-glutamatergic substances, the therapeutic mechanisms of SGAs might merge on a yet to be defined molecular level. In particular, serotonergic effects of SGAs, such as an agonism at 5HT1A receptors, represent important targets for further clinical research.
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Spiros A, Roberts P, Geerts H. A computer-based quantitative systems pharmacology model of negative symptoms in schizophrenia: exploring glycine modulation of excitation-inhibition balance. Front Pharmacol 2014; 5:229. [PMID: 25374541 PMCID: PMC4204440 DOI: 10.3389/fphar.2014.00229] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/23/2014] [Indexed: 02/04/2023] Open
Abstract
Although many antipsychotics can reasonably control positive symptoms in schizophrenia, patients' return to society is often hindered by negative symptoms and cognitive deficits. As an alternative to animal rodent models that are often not very predictive for the clinical situation, we developed a new computer-based mechanistic modeling approach. This Quantitative Systems Pharmacology approach combines preclinical basic neurophysiology of a biophysically realistic neuronal ventromedial cortical-ventral striatal network identified from human imaging studies that are associated with negative symptoms. Calibration of a few biological coupling parameters using a retrospective clinical database of 34 drug-dose combinations resulted in correlation coefficients greater than 0.60, while a robust quantitative prediction of a number of independent trials was observed. We then simulated the effect of glycine modulation on the anticipated clinical outcomes. The quantitative biochemistry of glycine interaction with the different NMDA-NR2 subunits, neurodevelopmental trajectory of the NMDA-NR2B in the human schizophrenia pathology, their specific localization on excitatory vs. inhibitory interneurons and the electrogenic nature of the glycine transporter resulted in an inverse U-shape dose-response with an optimum in the low micromolar glycine concentration. Quantitative systems pharmacology based computer modeling of complex humanized brain circuits is a powerful alternative approach to explain the non-monotonic dose-response observed in past clinical trial outcomes with sarcosine, D-cycloserine, glycine, or D-serine or with glycine transporter inhibitors. In general it can be helpful to better understand the human neurophysiology of negative symptoms, especially with targets that show non-monotonic dose-responses.
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Affiliation(s)
- Athan Spiros
- Computational Neuropharmacology, In Silico Biosciences, Inc. Berwyn, PA, USA
| | - Patrick Roberts
- Computational Neuropharmacology, In Silico Biosciences, Inc. Berwyn, PA, USA ; Department of Biomedical Engineering, Oregon Health and Science University Portland, OR, USA
| | - Hugo Geerts
- Computational Neuropharmacology, In Silico Biosciences, Inc. Berwyn, PA, USA ; Department of Laboratory Pathology, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, USA
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English BA, Thomas K, Johnstone J, Bazih A, Gertsik L, Ereshefsky L. Use of translational pharmacodynamic biomarkers in early-phase clinical studies for schizophrenia. Biomark Med 2014; 8:29-49. [PMID: 24325223 DOI: 10.2217/bmm.13.135] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Schizophrenia is a severe mental disorder characterized by cognitive deficits, and positive and negative symptoms. The development of effective pharmacological compounds for the treatment of schizophrenia has proven challenging and costly, with many compounds failing during clinical trials. Many failures occur due to disease heterogeneity and lack of predictive preclinical models and biomarkers that readily translate to humans during early characterization of novel antipsychotic compounds. Traditional early-phase trials consist of single- or multiple-dose designs aimed at determining the safety and tolerability of an investigational compound in healthy volunteers. However, by incorporating a translational approach employing methodologies derived from preclinical studies, such as EEG measures and imaging, into the traditional Phase I program, critical information regarding a compound's dose-response effects on pharmacodynamic biomarkers can be acquired. Furthermore, combined with the use of patients with stable schizophrenia in early-phase clinical trials, significant 'de-risking' and more confident 'go/no-go' decisions are possible.
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Elucidating the role of neurotensin in the pathophysiology and management of major mental disorders. Behav Sci (Basel) 2014; 4:125-153. [PMID: 25379273 PMCID: PMC4219245 DOI: 10.3390/bs4020125] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/15/2014] [Accepted: 05/21/2014] [Indexed: 12/30/2022] Open
Abstract
Neurotensin (NT) is a neuropeptide that is closely associated with, and is thought to modulate, dopaminergic and other neurotransmitter systems involved in the pathophysiology of various mental disorders. This review outlines data implicating NT in the pathophysiology and management of major mental disorders such as schizophrenia, drug addiction, and autism. The data suggest that NT receptor analogs have the potential to be used as novel therapeutic agents acting through modulation of neurotransmitter systems dys-regulated in these disorders.
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The relationship between glycine transporter 1 occupancy and the effects of the glycine transporter 1 inhibitor RG1678 or ORG25935 on object retrieval performance in scopolamine impaired rhesus monkey. Psychopharmacology (Berl) 2014; 231:511-9. [PMID: 24051602 DOI: 10.1007/s00213-013-3260-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 08/19/2013] [Indexed: 12/17/2022]
Abstract
Reduced NMDA receptor functioning is hypothesized to underlie the cognitive and negative symptoms associated with schizophrenia. However, because direct activation of the NMDA receptor is accompanied by neurotoxicity, mechanisms that activate the glycine co-agonist site on the NMDA receptor could carry greater therapeutic potential. In the current study, the effects of two glycine transporter 1 (GlyT1) inhibitors, RG1678 and ORG25935, were characterized in the object-retrieval detour (ORD) task in scopolamine-impaired rhesus monkeys and, using positron emission tomography (PET), the GlyT1 occupancy to efficacy relationship of each compound was established. Scopolamine exerted a significant decrease in accuracy in the ORD task. Lower doses of RG1678 (0.3 and 1.0 mg/kg, p.o.) significantly attenuated the impact of scopolamine, whereas the highest dose tested (1.8 mg/kg) did not. The predicted GlyT1 occupancies of RG1678 at the effective doses were ~10 and 30 %. ORG25935 (0.1, 0.3, and 1 mg/kg, p.o.) also significantly attenuated the impact of scopolamine on the ORD task, whereas 3 mg/kg did not. The predicted GlyT1 occupancies of ORG25935 at the effective doses ranged from 16 to 80 %. These data suggest that GlyT1 inhibitors have the potential to improve performance on prefrontal cortex-dependent tests such as the ORD task, but that efficacy is lost when higher occupancies are achieved. Importantly, recent Ph2B data published by Roche suggests that low but not high doses of RG1678 improved negative symptoms in patients with schizophrenia, highlighting the potential translational nature of the current preclinical findings.
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Liem-Moolenaar M, Peeters P, Kamerling IMC, Hogg C, Holder G, Kleijn HJ, Spaans E, Udo De Haes J, de Kam ML, Franson KL, Cohen AF, van Gerven JMA. Early stage development of the glycine-1 re-uptake inhibitor SCH 900435: central nervous system effects compared with placebo in healthy men. Br J Clin Pharmacol 2014; 75:1455-67. [PMID: 23116363 DOI: 10.1111/bcp.12015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 10/07/2012] [Indexed: 01/05/2023] Open
Abstract
AIMS To report the first three studies with SCH 900435, a selective glycine-1 re-uptake inhibitor in development for treating schizophrenia, using systematic evaluations of pharmacodynamics to understand the observed effects. METHODS Three double-blind, placebo-controlled studies (single, visual effect and multiple dose) were performed. In the single and multiple dose study SCH 900435 (0.5-30 mg) was given to healthy males and frequent pharmacokinetic and pharmacodynamic measurements were performed. The visual effects study incorporated visual electrophysiological measures of macular, retinal and intracranial visual pathway function. RESULTS In the single dose study (highest difference, 95% CI, P) increases in smooth pursuit eye movements (8, 12 mg (-6.09, 10.14, -2.04, 0.013), 30 mg), pupil : iris ratio (20 and 30 mg (-0.065, 0.09, -0.04, <0.0001)), VAS colour perception (30 mg (-9.48, 13.05, -5.91, <0.0001)) and changes in spontaneous reports of visual disturbance were found, while FSH (8 mg (0.42, 0.18, 0.66, 0.0015), 12, 20 mg), LH (8-30 mg (1.35, 0.65, 2.05, 0.0003)) and EEG alpha2 activity decreased (12, 20, 30 mg (0.27, 0.14, 0.41, 0.0002)). A subsequent dedicated visual effects study demonstrated that visual effects were transient without underlying electrophysiological changes. This provided enough safety information for starting a multiple ascending dose study, showing less visual symptoms after twice daily dosing and titration, possibly due to tolerance. CONCLUSIONS Several central nervous system (CNS) effects and gonadotropic changes resulted from administration of 8 mg and higher, providing evidence for CNS penetration and pharmacological activity of SCH 900435. Antipsychotic activity in patients, specificity of the reported effects for this drug class and possible tolerance to visual symptoms remain to be established.
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Glycine transporters as novel therapeutic targets in schizophrenia, alcohol dependence and pain. Nat Rev Drug Discov 2014; 12:866-85. [PMID: 24172334 DOI: 10.1038/nrd3893] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Glycine transporters are endogenous regulators of the dual functions of glycine, which acts as a classical inhibitory neurotransmitter at glycinergic synapses and as a modulator of neuronal excitation mediated by NMDA (N-methyl-D-aspartate) receptors at glutamatergic synapses. The two major subtypes of glycine transporters, GlyT1 and GlyT2, have been linked to the pathogenesis and/or treatment of central and peripheral nervous system disorders, including schizophrenia and related affective and cognitive disturbances, alcohol dependence, pain, epilepsy, breathing disorders and startle disease (also known as hyperekplexia). This Review examines the rationale for the therapeutic potential of GlyT1 and GlyT2 inhibition, and surveys the latest advances in the biology of glycine reuptake and transport as well as the drug discovery and clinical development of compounds that block glycine transporters.
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GlyT-1 Inhibitors: From Hits to Clinical Candidates. SMALL MOLECULE THERAPEUTICS FOR SCHIZOPHRENIA 2014. [DOI: 10.1007/7355_2014_53] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Menniti FS, Lindsley CW, Conn PJ, Pandit J, Zagouras P, Volkmann RA. Allosteric modulators for the treatment of schizophrenia: targeting glutamatergic networks. Curr Top Med Chem 2013; 13:26-54. [PMID: 23409764 DOI: 10.2174/1568026611313010005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 12/11/2012] [Accepted: 12/15/2012] [Indexed: 12/20/2022]
Abstract
Schizophrenia is a highly debilitating mental disorder which afflicts approximately 1% of the global population. Cognitive and negative deficits account for the lifelong disability associated with schizophrenia, whose symptoms are not effectively addressed by current treatments. New medicines are needed to treat these aspects of the disease. Neurodevelopmental, neuropathological, genetic, and behavioral pharmacological data indicate that schizophrenia stems from a dysfunction of glutamate synaptic transmission, particularly in frontal cortical networks. A number of novel pre- and postsynaptic mechanisms affecting glutamatergic synaptic transmission have emerged as viable targets for schizophrenia. While developing orthosteric glutamatergic agents for these targets has proven extremely difficult, targeting allosteric sites of these targets has emerged as a promising alternative. From a medicinal chemistry perspective, allosteric sites provide an opportunity of finding agents with better drug-like properties and greater target specificity. Furthermore, allosteric modulators are better suited to maintaining the highly precise temporal and spatial aspects of glutamatergic synaptic transmission. Herein, we review neuropathological and genomic/genetic evidence underscoring the importance of glutamate synaptic dysfunction in the etiology of schizophrenia and make a case for allosteric targets for therapeutic intervention. We review progress in identifying allosteric modulators of AMPA receptors, NMDA receptors, and metabotropic glutamate receptors, all with the aim of restoring physiological glutamatergic synaptic transmission. Challenges remain given the complexity of schizophrenia and the difficulty in studying cognition in animals and humans. Nonetheless, important compounds have emerged from these efforts and promising preclinical and variable clinical validation has been achieved.
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Woods SW, Walsh BC, Hawkins KA, Miller TJ, Saksa JR, D'Souza DC, Pearlson GD, Javitt DC, McGlashan TH, Krystal JH. Glycine treatment of the risk syndrome for psychosis: report of two pilot studies. Eur Neuropsychopharmacol 2013; 23:931-40. [PMID: 23089076 PMCID: PMC4028140 DOI: 10.1016/j.euroneuro.2012.09.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 09/18/2012] [Accepted: 09/18/2012] [Indexed: 11/30/2022]
Abstract
Patients meeting criteria for the risk syndrome for psychosis have treatment needs including positive and negative symptoms and cognitive impairment. These features could potentially respond to NMDA glycine-site agonists. The present objective was to determine which symptoms or domains of cognition promise to show the greatest response to glycine in risk syndrome patients. We conducted two short-term pilot studies of glycine used without adjunctive antipsychotic medication. In the first trial, 10 risk syndrome subjects received open-label glycine at doses titrated to 0.8 g/kg/d for 8 weeks, followed by discontinuation and 16 weeks of evaluation for durability of effects. In the second, 8 subjects were randomized to double-blind glycine vs. placebo for 12 weeks, followed by open-label glycine for another 12 weeks. Patients were evaluated every 1-2 weeks with the Scale Of Psychosis-risk Symptoms (SOPS) and before and after treatment with a neurocognitive battery. Within-group and between-group effect sizes were calculated. Effect sizes were large for positive (open-label within-group -1.10, double-blind between-group -1.11) and total (-1.39 and -1.15) symptoms and medium-to-large (-0.74 and -0.79) for negative symptoms. Medium or large effect sizes were also observed for several neurocognitive measures in the open-label study, although data were sparse. No safety concerns were identified. We conclude that glycine was associated with reduced symptoms with promising effect sizes in two pilot studies and a possibility of improvement in cognitive function. Further studies of agents that facilitate NMDA receptor function in risk syndrome patients are supported by these preliminary findings.
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Affiliation(s)
- Scott W Woods
- Yale University School of Medicine, New Haven, CT, USA.
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40
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Cioffi CL. Modulation of NMDA receptor function as a treatment for schizophrenia. Bioorg Med Chem Lett 2013; 23:5034-44. [PMID: 23916256 DOI: 10.1016/j.bmcl.2013.07.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/03/2013] [Accepted: 07/13/2013] [Indexed: 11/30/2022]
Abstract
Schizophrenia is a devastating mental illness that afflicts nearly 1% of the world's population. Currently available antipsychotics treat positive symptoms, but are largely ineffective at addressing negative symptoms and cognitive dysfunction. Thus, improved pharmacotherapies that treat all aspects of the disease remain a critical unmet need. There is mounting evidence that links NMDA receptor hypofunction and the expression of schizophrenia, and numerous drug discovery programs have developed agents that directly or indirectly potentiate NMDA receptor-mediated neurotransmission. Several compounds have emerged that show promise for treating all symptom sub-domains in both preclinical models and clinical studies, and we will review recent developments in many of these areas.
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Feasibility, safety, and efficacy of the combination of D-serine and computerized cognitive retraining in schizophrenia: an international collaborative pilot study. Neuropsychopharmacology 2013; 38:492-503. [PMID: 23093223 PMCID: PMC3547200 DOI: 10.1038/npp.2012.208] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The combination of pharmacotherapy and cognitive retraining (CRT) for the cognitive deficits of schizophrenia may be more efficacious than either approach alone, but this has not yet been tested. This study evaluated the feasibility, safety, tolerability, and efficacy of 12 weeks of D-serine, combined with CRT in the treatment of cognitive deficits in schizophrenia at two academic sites in parallel, in India and the United States. In a randomized, partial double-blind, placebo-controlled, parallel-group design, 104 schizophrenia subjects (US site=22, Indian site=82) were randomized to: (1) D-serine (30 mg/kg)+CRT (5 h/week), (2) D-serine+control CRT, (3) CRT+placebo D-serine, and (4) placebo+control CRT. Completion rates were 84 and 100% in the Indian and US samples, respectively. On various outcome measures of safety and tolerability, the interventions were well tolerated. D-Serine and CRT did not show any significant effect on the Global Cognitive Index, although both interventions showed differential site effects on individual test performance. CRT resulted in a significant improvement in Verbal Working Memory, and a trend toward improvement in Attention/Vigilance. This is the first study to demonstrating the feasibility, safety, and tolerability of combination pharmacotherapy and CRT in a multicenter international clinical trial. These preliminary findings provide support for future studies using higher doses of D-serine that have been shown to be efficacious or other pharmacotherapies, along with the newer cognitive remediation strategies that are individualized and that target basic information processing.
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Lakhan SE, Caro M, Hadzimichalis N. NMDA Receptor Activity in Neuropsychiatric Disorders. Front Psychiatry 2013; 4:52. [PMID: 23772215 PMCID: PMC3677126 DOI: 10.3389/fpsyt.2013.00052] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 05/25/2013] [Indexed: 01/03/2023] Open
Abstract
N-Methyl-d-aspartate (NMDA) receptors play a variety of physiologic roles and their proper signaling is essential for cellular homeostasis. Any disruption in this pathway, leading to either enhanced or decreased activity, may result in the manifestation of neuropsychiatric pathologies such as schizophrenia, mood disorders, substance induced psychosis, Huntington's disease, Alzheimer's disease, and neuropsychiatric systemic lupus erythematosus. Here, we explore the notion that the overlap in activity of at least one biochemical pathway, the NMDA receptor pathway, may be the link to understanding the overlap in psychotic symptoms between diseases. This review intends to present a broad overview of those neuropsychiatric disorders for which alternations in NMDA receptor activity is prominent thus suggesting that continued direction of pharmaceutical intervention to this pathway may present a viable option for managing symptoms.
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Affiliation(s)
- Shaheen E Lakhan
- Biosciences Department, Global Neuroscience Initiative Foundation , Beverly Hills, CA , USA ; Neurological Institute, Cleveland Clinic , Cleveland, OH , 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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D'Souza DC, Ahn K, Bhakta S, Elander J, Singh N, Nadim H, Jatlow P, Suckow RF, Pittman B, Ranganathan M. Nicotine fails to attenuate ketamine-induced cognitive deficits and negative and positive symptoms in humans: implications for schizophrenia. Biol Psychiatry 2012; 72:785-94. [PMID: 22717030 DOI: 10.1016/j.biopsych.2012.05.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 05/08/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND The uncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist, ketamine, induces a range of symptoms resembling those seen in schizophrenia. Enhancement of nicotinic acetylcholine receptor (nAChR) function may have potential as a treatment for the cognitive deficits and negative symptoms of schizophrenia. Accordingly, we examined the modulatory effects of brain nAChR systems on NMDAR antagonist-induced effects. METHODS The interactive effects of ketamine and nicotine were evaluated in 37 healthy subjects in a randomized, placebo-controlled, double-blind, crossover counterbalanced, 2 (intravenous ketamine or placebo) × 2 (intravenous nicotine or placebo) design. Verbal and visual memory, sustained attention, working memory, response inhibition, emotion recognition, executive function, reaction time, motor function, and speed of processing were assessed once per test day, while negative and positive symptoms, perceptual alterations, and a number of feeling states were measured several times before and after administration of drugs. RESULTS Ketamine induced cognitive deficits and negative and positive symptoms. Nicotine worsened immediate recall, auditory working memory, response inhibition, and executive function and serial processing. Nicotine decreased (improved) reaction time on the sustained attention and choice reaction time tasks. Nicotine did not reduce ketamine-induced cognitive deficits or negative and positive symptoms. CONCLUSIONS At blood levels comparable with tobacco smoking, nicotine infusion does not appear to alleviate the ketamine-induced transient cognitive and behavioral effects in healthy subjects that resemble those seen in schizophrenia. The lack of an effect of nicotine on a spectrum of ketamine effects suggests that the consequences of NMDAR antagonism are not likely under the direct influence of nAChR.
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Affiliation(s)
- Deepak Cyril D'Souza
- Psychiatry Service, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut, USA.
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Bifone A, Gozzi A. Neuromapping techniques in drug discovery: pharmacological MRI for the assessment of novel antipsychotics. Expert Opin Drug Discov 2012; 7:1071-82. [PMID: 22971143 DOI: 10.1517/17460441.2012.724057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Treatment of psychiatric and neurological diseases represents a substantial unmet medical need, but the development of novel, effective and safe drugs is proving difficult. While substantial improvement over existing pharmacological agents is expected from new molecular targets emerging in the genomic era, the validation and exploitation of novel mechanisms of action is a lengthy and costly process. The use of neuroimaging techniques, and more specifically of functional and pharmacological magnetic resonance imaging (MRI), has been advocated as a powerful approach to this problem, providing translational biomarkers for the objective assessment of drug activity on brain function, and possibly surrogate markers of clinical response. AREAS COVERED The authors review the recent application of functional and pharmacological MRI (phMRI) in the study of novel treatments of psychosis based on glutamatergic mechanisms. Furthermore, they review contribution of functional imaging in the target validation and early assessment of drugs exploiting glutamatergic mechanisms as an example of potentially impactful exploitation of neuroimaging methods in drug discovery. EXPERT OPINION While functional neuroimaging methods may provide useful markers of drug activity and response to treatment, their translational potential, that is, their use to bridge animal and human investigations is seldom exploited. The application of phMRI in the study of novel antipsychotics based on glutamatergic mechanisms represents an example of functional neuroimaging as a powerful means to link preclinical and clinical research, thus providing a paradigm that may help expedite progression into the clinical phase of novel mechanisms for the treatment of psychiatric and neurological diseases.
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Affiliation(s)
- Angelo Bifone
- Istituto Italiano di Tecnologia, Center for Nanotechnology Innovation @NEST, Pisa, Italy.
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Moghaddam B, Krystal JH. Capturing the angel in "angel dust": twenty years of translational neuroscience studies of NMDA receptor antagonists in animals and humans. Schizophr Bull 2012; 38:942-9. [PMID: 22899397 PMCID: PMC3446228 DOI: 10.1093/schbul/sbs075] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 04/24/2012] [Accepted: 04/27/2012] [Indexed: 01/09/2023]
Abstract
Here, we describe our collaborative efforts to use N-methyl-d-aspartate (NMDA) receptor antagonists as a translational tool to advance our understanding of the pathophysiology of schizophrenia and identify potential new targets for treatment of schizophrenia. We began these efforts in the late 1980s with a keen sense that, in both human and animal studies, we needed to move beyond the dopamine hypothesis of schizophrenia; if the dopamine hypothesis were correct, the existing dopamine antagonists should have cured the disease but they have not. We used NMDA receptor antagonists, not to produce schizophrenia, but as a tool to provide insights into effects of disturbances in glutamate synaptic function in schizophrenia. Our work has provided insights into potential mechanisms that may contribute to disrupted cortical function in schizophrenia and has helped identify potential treatment targets for the disorder. The translational nature of this study made the clinical testing of the first of these targets feasible. Advances in systems neuroscience approaches in animals and humans make new types of translational research possible; however, our concern is that the current obstacles facing translational research funding and academia-industry collaborations threaten the future progress in this field.
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MESH Headings
- Allosteric Regulation/drug effects
- Allosteric Regulation/physiology
- Animals
- Antipsychotic Agents/pharmacology
- Antipsychotic Agents/therapeutic use
- Brief Psychiatric Rating Scale
- Cerebral Cortex/drug effects
- Cerebral Cortex/physiopathology
- Disease Models, Animal
- Dopamine/metabolism
- Emotions/drug effects
- Emotions/physiology
- Glutamic Acid/physiology
- Humans
- Ketamine/pharmacology
- Neurosciences
- Phencyclidine/antagonists & inhibitors
- Phencyclidine/pharmacology
- Psychoses, Substance-Induced/physiopathology
- Receptor, Metabotropic Glutamate 5
- Receptors, Dopamine D2/drug effects
- Receptors, Dopamine D2/physiology
- Receptors, Metabotropic Glutamate/drug effects
- Receptors, Metabotropic Glutamate/physiology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Schizophrenia/drug therapy
- Schizophrenia/physiopathology
- Synapses/drug effects
- Synapses/physiology
- Translational Research, Biomedical
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Affiliation(s)
- Bita Moghaddam
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
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