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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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Ovalle Rodríguez P, Ramírez Ortega D, Blanco Ayala T, Roldán Roldán G, Pérez de la Cruz G, González Esquivel DF, Gómez-Manzo S, Sánchez Chapul L, Salazar A, Pineda B, Pérez de la Cruz V. Modulation of Kynurenic Acid Production by N-acetylcysteine Prevents Cognitive Impairment in Adulthood Induced by Lead Exposure during Lactation in Mice. Antioxidants (Basel) 2023; 12:2035. [PMID: 38136155 PMCID: PMC10740504 DOI: 10.3390/antiox12122035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 11/16/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023] Open
Abstract
Lead (Pb2+) exposure during early life induces cognitive impairment, which was recently associated with an increase in brain kynurenic acid (KYNA), an antagonist of NMDA and alpha-7 nicotinic receptors. It has been described that N-acetylcysteine (NAC) favors an antioxidant environment and inhibits kynurenine aminotransferase II activity (KAT II, the main enzyme of KYNA production), leading to brain KYNA levels decrease and cognitive improvement. This study aimed to investigate whether the NAC modulation of the brain KYNA levels in mice ameliorated Pb2+-induced cognitive impairment. The dams were divided into four groups: Control, Pb2+, NAC, and Pb2++NAC, which were given drinking water or 500 ppm lead acetate in the drinking water ad libitum, from 0 to 23 postnatal days (PNDs). The NAC and Pb2++NAC groups were simultaneously fed NAC (350 mg/day) in their chow from 0 to 23 PNDs. At PND 60, the effect of the treatment with Pb2+ and in combination with NAC on learning and memory performance was evaluated. Immediately after behavioral evaluation, brain tissues were collected to assess the redox environment; KYNA and glutamate levels; and KAT II activity. The NAC treatment prevented the long-term memory deficit exhibited in the Pb2+ group. As expected, Pb2+ group showed redox environment alterations, fluctuations in glutamate levels, and an increase in KYNA levels, which were partially avoided by NAC co-administration. These results confirmed that the excessive KYNA levels induced by Pb2+ were involved in the onset of cognitive impairment and could be successfully prevented by NAC treatment. NAC could be a tool for testing in scenarios in which KYNA levels are associated with the induction of cognitive impairment.
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Affiliation(s)
- Paulina Ovalle Rodríguez
- Neurochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (P.O.R.); (D.R.O.); (T.B.A.); (D.F.G.E.)
- Posgrado en Ciencias Bioquímicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Unidad de Posgrado, Mexico City 04510, Mexico
| | - Daniela Ramírez Ortega
- Neurochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (P.O.R.); (D.R.O.); (T.B.A.); (D.F.G.E.)
| | - Tonali Blanco Ayala
- Neurochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (P.O.R.); (D.R.O.); (T.B.A.); (D.F.G.E.)
| | - Gabriel Roldán Roldán
- Laboratorio de Neurobiología de la Conducta, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico;
| | - Gonzalo Pérez de la Cruz
- Department of Mathematics, Faculty of Sciences, Universidad Nacional Autónoma de México UNAM, Mexico City 04510, Mexico;
| | - Dinora Fabiola González Esquivel
- Neurochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (P.O.R.); (D.R.O.); (T.B.A.); (D.F.G.E.)
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico;
| | - Laura Sánchez Chapul
- Neuromuscular Diseases Laboratory, Clinical Neurosciences Division, National Institute of Rehabilitation “Luis Guillermo Ibarra Ibarra”, Mexico City 14389, Mexico;
| | - Aleli Salazar
- Neuroimmunology Department, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (A.S.); (B.P.)
| | - Benjamín Pineda
- Neuroimmunology Department, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (A.S.); (B.P.)
| | - Verónica Pérez de la Cruz
- Neurochemistry and Behavior Laboratory, National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez”, Mexico City 14269, Mexico; (P.O.R.); (D.R.O.); (T.B.A.); (D.F.G.E.)
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Li D, Yu S, Long Y, Shi A, Deng J, Ma Y, Wen J, Li X, Liu S, Zhang Y, Wan J, Li N, Ao R. Tryptophan metabolism: Mechanism-oriented therapy for neurological and psychiatric disorders. Front Immunol 2022; 13:985378. [PMID: 36159806 PMCID: PMC9496178 DOI: 10.3389/fimmu.2022.985378] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 08/11/2022] [Indexed: 12/04/2022] Open
Abstract
Neurological and psychiatric disorders are a category of chronic diseases that are widespread and pose serious mental and physical health problems for patients. The substrates, products, and enzymes of Tryptophan metabolism all contribute to the development of neurological and psychiatric disorders. This paper deals with three metabolic pathways of tryptophan that produce a series of metabolites called tryptophan Catabolics (TRYCATs). These metabolites are involved in pathological processes such as excitotoxicity, neuroinflammation, oxidative stress, and mitochondrial damage and are closely associated with neurological and psychiatric disorders such as Alzheimer’s disease and depression. Here, we review the elements that affect how tryptophan metabolism is regulated, including inflammation and stress, exercise, vitamins, minerals, diet and gut microbes, glucocorticoids, and aging, as well as the downstream regulatory effects of tryptophan metabolism, including the regulation of glutamate (Glu), immunity, G-protein coupled receptor 35 (Gpr35), nicotinic acetylcholine receptor (nAChR), aryl hydrocarbon receptor (AhR), and dopamine (DA). In order to advance the general understanding of tryptophan metabolism in neurological and psychiatric disorders, this paper also summarizes the current situation and effective drugs of tryptophan metabolism in the treatment of neurological and psychiatric disorders and considers its future research prospects.
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Affiliation(s)
- Dan Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Shuang Yu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yu Long
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Ai Shi
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jie Deng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yin Ma
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jing Wen
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xiaoqiu Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Songyu Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yulu Zhang
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jinyan Wan
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Nan Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- *Correspondence: Nan Li, ; Rui Ao,
| | - Rui Ao
- Oncology Center, Sichuan Provincial People's Hospital, Chengdu, China
- *Correspondence: Nan Li, ; Rui Ao,
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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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Mazzoccoli G, Kvetnoy I, Mironova E, Yablonskiy P, Sokolovich E, Krylova J, Carbone A, Anderson G, Polyakova V. The melatonergic pathway and its interactions in modulating respiratory system disorders. Biomed Pharmacother 2021; 137:111397. [PMID: 33761613 DOI: 10.1016/j.biopha.2021.111397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 02/08/2023] Open
Abstract
Melatonin is a key intracellular neuroimmune-endocrine regulator and coordinator of multiple complex and interrelated biological processes. The main functions of melatonin include the regulation of neuroendocrine and antioxidant system activity, blood pressure, rhythms of the sleep-wake cycle, the retardation of ageing processes, as well as reseting and optimizing mitochondria and thereby the cells of the immune system. Melatonin and its agonists have therefore been mooted as a treatment option across a wide array of medical disorders. This article reviews the role of melatonin in the regulation of respiratory system functions under normal and pathological conditions. Melatonin can normalize the structural and functional organization of damaged lung tissues, by a number of mechanisms, including the regulation of signaling molecules, oxidant status, lipid raft function, optimized mitochondrial function and reseting of the immune response over the circadian rhythm. Consequently, melatonin has potential clinical utility for bronchial asthma, chronic obstructive pulmonary disease, lung cancer, lung vascular diseases, as well as pulmonary and viral infections. The integration of melatonin's effects with the alpha 7 nicotinic receptor and the aryl hydrocarbon receptor in the regulation of mitochondrial function are proposed as a wider framework for understanding the role of melatonin across a wide array of diverse pulmonary disorders.
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Affiliation(s)
- Gianluigi Mazzoccoli
- Department of Medical Sciences, Division of Internal Medicine and Chronobiology Laboratory, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo 71013, Italy.
| | - Igor Kvetnoy
- Saint Petersburg Institute of Phthisiopulmonology, Lygovsky Ave. 2-4, Saint Petersburg 191036, Russian Federation; Department of Pathology, Saint Petersburg State University, University Embankment, 7/9, Saint Petersburg 199034, Russian Federation
| | - Ekaterina Mironova
- Saint Petersburg Institute of Bioregulation and Gerontology, Dynamo Ave., 3, Saint Petersburg 197110, Russian Federation
| | - Petr Yablonskiy
- Saint Petersburg Institute of Phthisiopulmonology, Lygovsky Ave. 2-4, Saint Petersburg 191036, Russian Federation
| | - Evgenii Sokolovich
- Saint Petersburg Institute of Phthisiopulmonology, Lygovsky Ave. 2-4, Saint Petersburg 191036, Russian Federation
| | - Julia Krylova
- Saint Petersburg Institute of Phthisiopulmonology, Lygovsky Ave. 2-4, Saint Petersburg 191036, Russian Federation; Pavlov First Saint Petersburg State Medical University, Lev Tolstoy str. 6-8, Saint Petersburg 197022, Russian Federation
| | - Annalucia Carbone
- Department of Medical Sciences, Division of Internal Medicine and Chronobiology Laboratory, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo 71013, Italy
| | | | - Victoria Polyakova
- Saint Petersburg Institute of Phthisiopulmonology, Lygovsky Ave. 2-4, Saint Petersburg 191036, Russian Federation; St. Petersburg State Pediatric Medical University, Litovskaia str. 2, Saint-Petersburg 194100, Russian Federation
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Jorratt P, Hoschl C, Ovsepian SV. Endogenous antagonists of N-methyl-d-aspartate receptor in schizophrenia. Alzheimers Dement 2020; 17:888-905. [PMID: 33336545 DOI: 10.1002/alz.12244] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/24/2020] [Indexed: 12/28/2022]
Abstract
Schizophrenia is a chronic neuropsychiatric brain disorder that has devastating personal impact and rising healthcare costs. Dysregulation of glutamatergic neurotransmission has been implicated in the pathobiology of the disease, attributed largely to the hypofunction of the N-methyl-d-aspartate (NMDA) receptor. Currently, there is a major gap in mechanistic analysis as to how endogenous modulators of the NMDA receptors contribute to the onset and progression of the disease. We present a systematic review of the neurobiology and the role of endogenous NMDA receptor antagonists in animal models of schizophrenia, and in patients. We discuss their neurochemical origin, release from neurons and glia with action mechanisms, and functional effects, which might contribute toward the impairment of neuronal processes underlying this complex pathological state. We consider clinical evidence suggesting dysregulations of endogenous NMDA receptor in schizophrenia, and highlight the pressing need in future studies and emerging directions, to restore the NMDA receptor functions for therapeutic benefits.
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Affiliation(s)
- Pascal Jorratt
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Department of Psychiatry and Medical Psychology, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Cyril Hoschl
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Department of Psychiatry and Medical Psychology, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Saak V Ovsepian
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Department of Psychiatry and Medical Psychology, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
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7
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Stone TW. Does kynurenic acid act on nicotinic receptors? An assessment of the evidence. J Neurochem 2020; 152:627-649. [PMID: 31693759 PMCID: PMC7078985 DOI: 10.1111/jnc.14907] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/19/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023]
Abstract
As a major metabolite of kynurenine in the oxidative metabolism of tryptophan, kynurenic acid is of considerable biological and clinical importance as an endogenous antagonist of glutamate in the central nervous system. It is most active as an antagonist at receptors sensitive to N-methyl-D-aspartate (NMDA) which regulate neuronal excitability and plasticity, brain development and behaviour. It is also thought to play a causative role in hypo-glutamatergic conditions such as schizophrenia, and a protective role in several neurodegenerative disorders, notably Huntington's disease. An additional hypothesis, that kynurenic acid could block nicotinic receptors for acetylcholine in the central nervous system has been proposed as an alternative mechanism of action of kynurenate. However, the evidence for this alternative mechanism is highly controversial, partly because at least eight earlier studies concluded that kynurenic acid blocked NMDA receptors but not nicotinic receptors and five subsequent, independent studies designed to repeat the results have failed to do so. Many studies considered to support the alternative 'nicotinic' hypothesis have been based on the use of analogs of kynurenate such as 7-chloro-kynurenic acid, or putatively nicotinic modulators such as galantamine, but a detailed analysis of the pharmacology of these compounds suggests that the results have often been misinterpreted, especially since the pharmacology of galantamine itself has been disputed. This review examines the evidence in detail, with the conclusion that there is no confirmed, reliable evidence for an antagonist activity of kynurenic acid at nicotinic receptors. Therefore, since there is overwhelming evidence for kynurenate acting at ionotropic glutamate receptors, especially NMDAR glutamate and glycine sites, with some activity at GPR35 sites and Aryl Hydrocarbon Receptors, results with kynurenic acid should be interpreted only in terms of these confirmed sites of action.
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Affiliation(s)
- Trevor W. Stone
- Institute for Neuroscience and PsychologyUniversity of GlasgowGlasgowG12 8QQUK
- Present address:
Kennedy InstituteNDORMSUniversity of OxfordOxfordOX3 7FYUK
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Skolnick SD, Greig NH. Microbes and Monoamines: Potential Neuropsychiatric Consequences of Dysbiosis. Trends Neurosci 2019; 42:151-163. [PMID: 30795845 DOI: 10.1016/j.tins.2018.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/31/2018] [Accepted: 12/18/2018] [Indexed: 12/21/2022]
Abstract
From an evolutionary perspective, the genes of enteric microbes transmitted reliably across generations are nearly as much a part of the human organism as our own genes. Disruption of the microbiome leading to extinction of key 'heirloom' taxa can deprive individuals of metabolic pathways that have been present in their ancestors for millennia. Some of these pathways support essential synthesis and toxin clearance processes, including the generation of blood-brain barrier-crossing metabolic products crucial for normal brain function. Here, we discuss three such pathways: endogenous benzodiazepine synthesis, production of queuine/queuosine, and excretion of dietary mercury. Among them, these pathways have the potential to impact systems relevant to a wide range of neurodevelopmental and psychiatric conditions including autism, depression, anxiety, and schizophrenia.
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Affiliation(s)
- Stephen D Skolnick
- Drug Design & Development Section, Translational Gerontology Branch, Biomedical Research Center, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
| | - Nigel H Greig
- Drug Design & Development Section, Translational Gerontology Branch, Biomedical Research Center, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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Korte-Bouws GAH, Albers E, Voskamp M, Hendriksen H, de Leeuw LR, Güntürkün O, de Roock S, Vastert SJ, Korte SM. Juvenile Arthritis Patients Suffering from Chronic Inflammation Have Increased Activity of Both IDO and GTP-CH1 Pathways But Decreased BH4 Efficacy: Implications for Well-Being, Including Fatigue, Cognitive Impairment, Anxiety, and Depression. Pharmaceuticals (Basel) 2019; 12:E9. [PMID: 30625990 PMCID: PMC6469185 DOI: 10.3390/ph12010009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/24/2018] [Accepted: 12/29/2018] [Indexed: 12/27/2022] Open
Abstract
Juvenile idiopathic arthritis (JIA) represents joint inflammation with an unknown cause that starts before the age of 16, resulting in stiff and painful joints. In addition, JIA patients often report symptoms of sickness behavior. Recent animal studies suggest that proinflammatory cytokines produce sickness behavior by increasing the activity of indoleamine-2,3-dioxygenase (IDO) and guanosinetriphosphate⁻cyclohydrolase-1 (GTP⁻CH1). Here, it is hypothesized that inflammation in JIA patients enhances the enzymatic activity of IDO and GTP-CH1 and decreases the co-factor tetrahydrobiopterin (BH4). These compounds play a crucial role in the synthesis and metabolism of neurotransmitters. The aim of our study was to reveal whether inflammation affects both the GTP-CH1 and IDO pathway in JIA patients. Serum samples were collected from twenty-four JIA patients. In these samples, the concentrations of tryptophan (TRP), kynurenine (KYN), tyrosine (TYR), neopterin, and phenylalanine (PHE) were measured. An HPLC method with electrochemical detection was developed to quantify tryptophan, kynurenine, and tyrosine. Neopterin and phenylalanine were quantified by ELISA. The KYN/TRP ratio was measured as an index of IDO activity, while the PHE/TYR ratio was measured as an index of BH4 activity. Neopterin concentrations were used as an indirect measure of GTP-CH1 activity. JIA patients with high disease activity showed higher levels of both neopterin and kynurenine, and a higher ratio of both KYN/TRP and PHE/TYR and lower tryptophan levels than clinically inactive patients. Altogether, these data support our hypothesis that inflammation increases the enzymatic activity of both IDO and GTP-CH1 but decreases the efficacy of the co-factor BH4. In the future, animal studies are needed to investigate whether inflammation-induced changes in these enzymatic pathways and co-factor BH4 lower the levels of the brain neurotransmitters glutamate, noradrenaline, dopamine, serotonin, and melatonin, and consequently, whether they may affect fatigue, cognition, anxiety, and depression. Understanding of these complex neuroimmune interactions provides new possibilities for Pharma-Food interventions to improve the quality of life of patients suffering from chronic inflammation.
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Affiliation(s)
- Gerdien A H Korte-Bouws
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
| | - Eline Albers
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
| | - Marije Voskamp
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
| | - Hendrikus Hendriksen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
| | - Lidewij R de Leeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
| | - Onur Güntürkün
- Department of Biopsychology, Faculty of Psychology, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany.
| | - Sytze de Roock
- Paediatric Rheumatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands.
| | - Sebastiaan J Vastert
- Paediatric Rheumatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands.
| | - S Mechiel Korte
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Faculty of Science, Universities 99, 3584 CG Utrecht, The Netherlands.
- Department of Biopsychology, Faculty of Psychology, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany.
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Tufvesson-Alm M, Schwieler L, Schwarcz R, Goiny M, Erhardt S, Engberg G. Importance of kynurenine 3-monooxygenase for spontaneous firing and pharmacological responses of midbrain dopamine neurons: Relevance for schizophrenia. Neuropharmacology 2018; 138:130-139. [PMID: 29879409 DOI: 10.1016/j.neuropharm.2018.06.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 06/01/2018] [Accepted: 06/03/2018] [Indexed: 12/15/2022]
Abstract
Kynurenine 3-monooxygenase (KMO) is an essential enzyme of the kynurenine pathway, converting kynurenine into 3-hydroxykynurenine. Inhibition of KMO increases kynurenine, resulting in elevated levels of kynurenic acid (KYNA), an endogenous N-methyl-d-aspartate and α*7-nicotinic receptor antagonist. The concentration of KYNA is elevated in the brain of patients with schizophrenia, possibly as a result of a reduced KMO activity. In the present study, using in vivo single cell recording techniques, we investigated the electrophysiological characteristics of ventral tegmental area dopamine (VTA DA) neurons and their response to antipsychotic drugs in a KMO knock-out (K/O) mouse model. KMO K/O mice exhibited a marked increase in spontaneous VTA DA neuron activity as compared to wild-type (WT) mice. Furthermore, VTA DA neurons showed clear-cut, yet qualitatively opposite, responses to the antipsychotic drugs haloperidol and clozapine in the two genotypes. The anti-inflammatory drug parecoxib successfully lowered the firing activity of VTA DA neurons in KMO K/O, but not in WT mice. Minocycline, an antibiotic and anti-inflammatory drug, produced no effect in this regard. Taken together, the present data further support the usefulness of KMO K/O mice for studying distinct aspects of the pathophysiology and pharmacological treatment of psychiatric disorders such as schizophrenia.
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Affiliation(s)
| | - Lilly Schwieler
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Michel Goiny
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Sophie Erhardt
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Göran Engberg
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden; Department of Physiology and Pharmacology, Karolinska Institute, Biomedicum 5C, 171 77, Stockholm, Sweden.
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11
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Plitman E, Iwata Y, Caravaggio F, Nakajima S, Chung JK, Gerretsen P, Kim J, Takeuchi H, Chakravarty MM, Remington G, Graff-Guerrero A. Kynurenic Acid in Schizophrenia: A Systematic Review and Meta-analysis. Schizophr Bull 2017; 43:764-777. [PMID: 28187219 PMCID: PMC5472151 DOI: 10.1093/schbul/sbw221] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Kynurenic acid (KYNA) is an endogenous antagonist of N-methyl-D-aspartate and α7 nicotinic acetylcholine receptors that is derived from astrocytes as part of the kynurenine pathway of tryptophan degradation. Evidence suggests that abnormal KYNA levels are involved in the pathophysiology of schizophrenia. However, this has never been assessed through a meta-analysis. A literature search was conducted through Ovid using Embase, Medline, and PsycINFO databases (last search: December 2016) with the search terms: (kynuren* or KYNA) and (schizophreni* or psychosis). English language studies measuring KYNA levels using any method in patients with schizophrenia and healthy controls (HCs) were identified. Standardized mean differences (SMDs) were calculated to determine differences in KYNA levels between groups. Subgroup analyses were separately performed for nonoverlapping participant samples, KYNA measurement techniques, and KYNA sample source. The influences of patients' age, antipsychotic status (%medicated), and sex (%male) on study SMDs were assessed through a meta-regression. Thirteen studies were deemed eligible for inclusion in the meta-analysis. In the main analysis, KYNA levels were elevated in the patient group. Subgroup analyses demonstrated that KYNA levels were increased in nonoverlapping participant samples, and centrally (cerebrospinal fluid and brain tissue) but not peripherally. Patients' age, %medicated, and %male were each positively associated with study SMDs. Overall, KYNA levels are increased in patients with schizophrenia, specifically within the central nervous system. An improved understanding of KYNA in patients with schizophrenia may contribute to the development of novel diagnostic approaches and therapeutic strategies.
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Affiliation(s)
- Eric Plitman
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Yusuke Iwata
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Fernando Caravaggio
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Shinichiro Nakajima
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Department of Psychiatry, University of Toronto, Toronto, ON, Canada;,Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Department of Neuropsychiatry, Keio University, Tokyo, Japan
| | - Jun Ku Chung
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Philip Gerretsen
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Department of Psychiatry, University of Toronto, Toronto, ON, Canada;,Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Julia Kim
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Hiroyoshi Takeuchi
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada;,Department of Neuropsychiatry, Keio University, Tokyo, Japan;,Schizophrenia Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - M. Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada;,Departments of Psychiatry and Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Gary Remington
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada;,Department of Psychiatry, University of Toronto, Toronto, ON, Canada;,Schizophrenia Division, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Campbell Institute Research Program, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Ariel Graff-Guerrero
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Institute of Medical Science, University of Toronto, Toronto, ON, Canada;,Department of Psychiatry, University of Toronto, Toronto, ON, Canada;,Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, ON, Canada;,Campbell Institute Research Program, Centre for Addiction and Mental Health, Toronto, ON, Canada
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12
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Serum kynurenic acid is reduced in affective psychosis. Transl Psychiatry 2017; 7:e1115. [PMID: 28463241 PMCID: PMC5534956 DOI: 10.1038/tp.2017.88] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/26/2017] [Accepted: 03/26/2017] [Indexed: 12/17/2022] Open
Abstract
A subgroup of individuals with mood and psychotic disorders shows evidence of inflammation that leads to activation of the kynurenine pathway and the increased production of neuroactive kynurenine metabolites. Depression is hypothesized to be causally associated with an imbalance in the kynurenine pathway, with an increased metabolism down the 3-hydroxykynurenine (3HK) branch of the pathway leading to increased levels of the neurotoxic metabolite, quinolinic acid (QA), which is a putative N-methyl-d-aspartate (NMDA) receptor agonist. In contrast, schizophrenia and psychosis are hypothesized to arise from increased metabolism of the NMDA receptor antagonist, kynurenic acid (KynA), leading to hypofunction of GABAergic interneurons, the disinhibition of pyramidal neurons and striatal hyperdopaminergia. Here we present results that challenge the model of excess KynA production in affective psychosis. After rigorous control of potential confounders and multiple testing we find significant reductions in serum KynA and/or KynA/QA in acutely ill inpatients with major depressive disorder (N=35), bipolar disorder (N=53) and schizoaffective disorder (N=40) versus healthy controls (N=92). No significant difference was found between acutely ill inpatients with schizophrenia (n=21) and healthy controls. Further, a post hoc comparison of patients divided into the categories of non-psychotic affective disorder, affective psychosis and psychotic disorder (non-affective) showed that the greatest decrease in KynA was in the affective psychosis group relative to the other diagnostic groups. Our results are consistent with reports of elevations in proinflammatory cytokines in psychosis, and preclinical work showing that inflammation upregulates the enzyme, kynurenine mono-oxygenase (KMO), which converts kynurenine into 3-hydroxykynurenine and quinolinic acid.
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13
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The kynurenine pathway in schizophrenia and bipolar disorder. Neuropharmacology 2017; 112:297-306. [DOI: 10.1016/j.neuropharm.2016.05.020] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 11/20/2022]
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14
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Schwarcz R, Stone TW. The kynurenine pathway and the brain: Challenges, controversies and promises. Neuropharmacology 2017; 112:237-247. [PMID: 27511838 PMCID: PMC5803785 DOI: 10.1016/j.neuropharm.2016.08.003] [Citation(s) in RCA: 252] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/29/2016] [Accepted: 08/05/2016] [Indexed: 12/29/2022]
Abstract
Research on the neurobiology of the kynurenine pathway has suffered years of relative obscurity because tryptophan degradation, and its involvement in both physiology and major brain diseases, was viewed almost exclusively through the lens of the well-established metabolite serotonin. With increasing recognition that kynurenine and its metabolites can affect and even control a variety of classic neurotransmitter systems directly and indirectly, interest is expanding rapidly. Moreover, kynurenine pathway metabolism itself is modulated in conditions such as infection and stress, which are known to induce major changes in well-being and behaviour, so that kynurenines may be instrumental in the etiology of psychiatric and neurological disorders. It is therefore likely that the near future will not only witness the discovery of additional physiological and pathological roles for brain kynurenines, but also ever-increasing interest in drug development based on these roles. In particular, targeting the kynurenine pathway with new specific agents may make it possible to prevent disease by appropriate pharmacological or genetic manipulations. The following overview focuses on areas of kynurenine research which are either controversial, of major potential therapeutic interest, or just beginning to receive the degree of attention which will clarify their relevance to neurobiology and medicine. It also highlights technical issues so that investigators entering the field, and new research initiatives, are not misdirected by inappropriate experimental approaches or incorrect interpretations at this time of skyrocketing interest in the subject matter. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'.
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Affiliation(s)
- Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Trevor W Stone
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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15
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Parrott JM, Redus L, Santana-Coelho D, Morales J, Gao X, O'Connor JC. Neurotoxic kynurenine metabolism is increased in the dorsal hippocampus and drives distinct depressive behaviors during inflammation. Transl Psychiatry 2016; 6:e918. [PMID: 27754481 PMCID: PMC5315555 DOI: 10.1038/tp.2016.200] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/28/2016] [Accepted: 08/17/2016] [Indexed: 12/30/2022] Open
Abstract
The kynurenine pathway of tryptophan metabolism has an important role in mediating the behavioral effects of inflammation, which has implications in understanding neuropsychiatric comorbidity and for the development of novel therapies. Inhibition of the rate-limiting enzyme, indoleamine 2,3-dioxygenase (IDO), prevents the development of many of these inflammation-induced preclinical behaviors. However, dysregulation in the balance of downstream metabolism, where neuroactive kynurenines are generated, is hypothesized to be a functionally important pathogenic feature of inflammation-induced depression. Here we utilized two novel transgenic mouse strains to directly test the hypothesis that neurotoxic kynurenine metabolism causes depressive-like behavior following peripheral immune activation. Wild-type (WT) or kynurenine 3-monooxygenase (KMO)-deficient (KMO-/-) mice were administered either lipopolysaccharide (LPS, 0.5 mg kg-1) or saline intraperitoneally. Depressive-like behavior was measured across multiple domains 24 h after immune challenge. LPS precipitated a robust depressive-like phenotype, but KMO-/- mice were specifically protected from LPS-induced immobility in the tail suspension test (TST) and reduced spontaneous alternations in the Y-maze. Direct administration of 3-hydroxykynurenine, the metabolic product of KMO, caused a dose-dependent increase in depressive-like behaviors. Mice with targeted deletion of 3-hydroxyanthranilic acid dioxygenase (HAAO), the enzyme that generates quinolinic acid, were similarly challenged with LPS. Similar to KMO-/- mice, LPS failed to increase immobility during the TST. Whereas kynurenine metabolism was generally increased in behaviorally salient brain regions, a distinct shift toward KMO-dependent kynurenine metabolism occurred in the dorsal hippocampus in response to LPS. Together, these results demonstrate that KMO is a pivotal mediator of hippocampal-dependent depressive-like behaviors induced by peripheral LPS challenge.
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Affiliation(s)
- J M Parrott
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - L Redus
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - D Santana-Coelho
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - J Morales
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - X Gao
- Department of Biochemistry, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - J C O'Connor
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,Audie L. Murphy Memorial VA Hospital, South Texas Veterans Health System, San Antonio, TX, USA,Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, 216B Medical Building MC-7764, San Antonio, TX 78229, USA. E-mail:
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16
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Inhibition of kynurenine aminotransferase II reduces activity of midbrain dopamine neurons. Neuropharmacology 2016; 102:42-7. [DOI: 10.1016/j.neuropharm.2015.10.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 01/25/2023]
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17
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Eells JB, Varela-Stokes A, Guo-Ross SX, Kummari E, Smith HM, Cox AD, Lindsay DS. Chronic Toxoplasma gondii in Nurr1-null heterozygous mice exacerbates elevated open field activity. PLoS One 2015; 10:e0119280. [PMID: 25855987 PMCID: PMC4391871 DOI: 10.1371/journal.pone.0119280] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/20/2015] [Indexed: 12/19/2022] Open
Abstract
Latent infection with Toxoplasma gondii is common in humans (approximately 30% of the global population) and is a significant risk factor for schizophrenia. Since prevalence of T. gondii infection is far greater than prevalence of schizophrenia (0.5-1%), genetic risk factors are likely also necessary to contribute to schizophrenia. To test this concept in an animal model, Nurr1-null heterozygous (+/-) mice and wild-type (+/+) mice were evaluate using an emergence test, activity in an open field and with a novel object, response to bobcat urine and prepulse inhibition of the acoustic startle response (PPI) prior to and 6 weeks after infection with T. gondii. In the emergence test, T. gondii infection significantly decreased the amount of time spent in the cylinder. Toxoplasma gondii infection significantly elevated open field activity in both +/+ and +/- mice but this increase was significantly exacerbated in +/- mice. T. gondii infection reduced PPI in male +/- mice but this was not statistically significant. Aversion to bobcat urine was abolished by T. gondii infection in +/+ mice. In female +/- mice, aversion to bobcat urine remained after T. gondii infection while the male +/- mice showed no aversion to bobcat urine. Antibody titers of infected mice were a critical variable associated with changes in open field activity, such that an inverted U shaped relationship existed between antibody titers and the percent change in open field activity with a significant increase in activity at low and medium antibody titers but no effect at high antibody titers. These data demonstrate that the Nurr1 +/- genotype predisposes mice to T. gondii-induced alterations in behaviors that involve dopamine neurotransmission and are associated with symptoms of schizophrenia. We propose that these alterations in murine behavior were due to further exacerbation of the altered dopamine neurotransmission in Nurr1 +/- mice.
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Affiliation(s)
- Jeffrey B. Eells
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
- * E-mail:
| | - Andrea Varela-Stokes
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Shirley X. Guo-Ross
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Evangel Kummari
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Holly M. Smith
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Arin D. Cox
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - David S. Lindsay
- Department of Biomedical Sciences & Pathobiology, Virginia–Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
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18
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Parrott JM, O'Connor JC. Kynurenine 3-Monooxygenase: An Influential Mediator of Neuropathology. Front Psychiatry 2015; 6:116. [PMID: 26347662 PMCID: PMC4542134 DOI: 10.3389/fpsyt.2015.00116] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/03/2015] [Indexed: 12/13/2022] Open
Abstract
Mounting evidence demonstrates that kynurenine metabolism may play an important pathogenic role in the development of multiple neurological and neuropsychiatric disorders. The kynurenine pathway consists of two functionally distinct branches that generate both neuroactive and oxidatively reactive metabolites. In the brain, the rate-limiting enzyme for one of these branches, kynurenine 3-monooxygenase (KMO), is predominantly expressed in microglia and has emerged as a pivotal point of metabolic regulation. KMO substrate and expression levels are upregulated by pro-inflammatory cytokines and altered by functional genetic mutations. Increased KMO metabolism results in the formation of metabolites that activate glutamate receptors and elevate oxidative stress, while recent evidence has revealed neurodevelopmental consequences of reduced KMO activity. Together, the evidence suggests that KMO is positioned at a critical metabolic junction to influence the development or trajectory of a myriad of neurological diseases. Understanding the mechanism(s) by which alterations in KMO activity are able to impair neuronal function, and viability will enhance our knowledge of related disease pathology and provide insight into novel therapeutic opportunities. This review will discuss the influence of KMO on brain kynurenine metabolism and the current understanding of molecular mechanisms by which altered KMO activity may contribute to neurodevelopment, neurodegenerative, and neuropsychiatric diseases.
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Affiliation(s)
- Jennifer M Parrott
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX , USA ; Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio , San Antonio, TX , USA
| | - Jason C O'Connor
- Department of Pharmacology, School of Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX , USA ; Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio , San Antonio, TX , USA ; Mood Disorders Translational Research Core, University of Texas Health Science Center at San Antonio , San Antonio, TX , USA ; Audie L. Murphy Memorial VA Hospital, South Texas Veterans Health System , San Antonio, TX , USA
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19
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Stone TW, Darlington LG. The kynurenine pathway as a therapeutic target in cognitive and neurodegenerative disorders. Br J Pharmacol 2014; 169:1211-27. [PMID: 23647169 DOI: 10.1111/bph.12230] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/16/2013] [Accepted: 04/24/2013] [Indexed: 02/06/2023] Open
Abstract
Understanding the neurochemical basis for cognitive function is one of the major goals of neuroscience, with a potential impact on the diagnosis, prevention and treatment of a range of psychiatric and neurological disorders. In this review, the focus will be on a biochemical pathway that remains under-recognized in its implications for brain function, even though it can be responsible for moderating the activity of two neurotransmitters fundamentally involved in cognition - glutamate and acetylcholine. Since this pathway - the kynurenine pathway of tryptophan metabolism - is induced by immunological activation and stress, it also stands in a unique position to mediate the effects of environmental factors on cognition and behaviour. Targeting the pathway for new drug development could, therefore, be of value not only for the treatment of existing psychiatric conditions, but also for preventing the development of cognitive disorders in response to environmental pressures.
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Affiliation(s)
- Trevor W Stone
- Institute of Neuroscience & Psychology, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.
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20
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Anderson G, Maes M. Redox Regulation and the Autistic Spectrum: Role of Tryptophan Catabolites, Immuno-inflammation, Autoimmunity and the Amygdala. Curr Neuropharmacol 2014; 12:148-67. [PMID: 24669209 PMCID: PMC3964746 DOI: 10.2174/1570159x11666131120223757] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 08/18/2013] [Accepted: 11/02/2013] [Indexed: 12/12/2022] Open
Abstract
The autistic spectrum disorders (ASD) form a set of multi-faceted disorders with significant genetic, epigenetic and environmental determinants. Oxidative and nitrosative stress (O&NS), immuno-inflammatory pathways, mitochondrial dysfunction and dysregulation of the tryptophan catabolite (TRYCATs) pathway play significant interactive roles in driving the early developmental etiology and course of ASD. O&NS interactions with immuno-inflammatory pathways mediate their effects centrally via the regulation of astrocyte and microglia responses, including regional variations in TRYCATs produced. Here we review the nature of these interactions and propose an early developmental model whereby different ASD genetic susceptibilities interact with environmental and epigenetic processes, resulting in glia biasing the patterning of central interarea interactions. A role for decreased local melatonin and N-acetylserotonin production by immune and glia cells may be a significant treatment target.
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Affiliation(s)
| | - Michael Maes
- Department of Psychiatry, Chulalongkorn University, Bangkok, Thailand
- Department of Psychiatry, Deakin University, Geelong, Australia
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21
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Liu X, Holtze M, Powell SB, Terrando N, Larsson MK, Persson A, Olsson SK, Orhan F, Kegel M, Asp L, Goiny M, Schwieler L, Engberg G, Karlsson H, Erhardt S. Behavioral disturbances in adult mice following neonatal virus infection or kynurenine treatment--role of brain kynurenic acid. Brain Behav Immun 2014; 36:80-9. [PMID: 24140727 PMCID: PMC3947209 DOI: 10.1016/j.bbi.2013.10.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 09/25/2013] [Accepted: 10/11/2013] [Indexed: 12/31/2022] Open
Abstract
Exposure to infections in early life is considered a risk-factor for developing schizophrenia. Recently we reported that a neonatal CNS infection with influenza A virus in mice resulted in a transient induction of the brain kynurenine pathway, and subsequent behavioral disturbances in immune-deficient adult mice. The aim of the present study was to investigate a potential role in this regard of kynurenic acid (KYNA), an endogenous antagonist at the glycine site of the N-methyl-D-aspartic acid (NMDA) receptor and at the cholinergic α7 nicotinic receptor. C57BL/6 mice were injected i.p. with neurotropic influenza A/WSN/33 virus (2400 plaque-forming units) at postnatal day (P) 3 or with L-kynurenine (2×200 mg/kg/day) at P7-16. In mice neonatally treated with L-kynurenine prepulse inhibition of the acoustic startle, anxiety, and learning and memory were also assessed. Neonatally infected mice showed enhanced sensitivity to D-amphetamine-induced (5 mg/kg i.p.) increase in locomotor activity as adults. Neonatally L-kynurenine treated mice showed enhanced sensitivity to D-amphetamine-induced (5 mg/kg i.p.) increase in locomotor activity as well as mild impairments in prepulse inhibition and memory. Also, D-amphetamine tended to potentiate dopamine release in the striatum in kynurenine-treated mice. These long-lasting behavioral and neurochemical alterations suggest that the kynurenine pathway can link early-life infection with the development of neuropsychiatric disturbances in adulthood.
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Affiliation(s)
- Xicong Liu
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Maria Holtze
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Susan B Powell
- Department of Psychiatry, University of California San Diego, La Jolla, California, USA
| | - Niccolò Terrando
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Markus K. Larsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Anna Persson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Sara K. Olsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Funda Orhan
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Magdalena Kegel
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Linnea Asp
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Michel Goiny
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Lilly Schwieler
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Göran Engberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Karlsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sophie Erhardt
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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22
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Olsson SK, Sellgren C, Engberg G, Landén M, Erhardt S. Cerebrospinal fluid kynurenic acid is associated with manic and psychotic features in patients with bipolar I disorder. Bipolar Disord 2012; 14:719-26. [PMID: 23030601 DOI: 10.1111/bdi.12009] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Kynurenic acid (KYNA), an end metabolite of tryptophan degradation, antagonizes glutamatergic and cholinergic receptors in the brain. Recently, we reported elevated levels of cerebrospinal fluid (CSF) KYNA in male patients with bipolar disorder. Here, we investigate the relationship between symptomatology and the concentration of CSF KYNA in patients with bipolar I disorder. METHODS CSF KYNA levels from euthymic male {n = 21; mean age: 41 years [standard deviation (SD) = 14]} and female [n = 34; mean age: 37 years (SD = 14)] patients diagnosed with bipolar I disorder were analyzed using high-performance liquid chromatography (HPLC). RESULTS Euthymic bipolar I disorder patients with a lifetime occurrence of psychotic features had higher CSF levels of KYNA {2.0 nm [standard error of the mean (SEM) = 0.2]; n = 43} compared to patients without any history of psychotic features [1.3 nm (SEM = 0.2); n = 12] (p = 0.01). Logistic regression, with age as covariate, similarly showed an association between a history of psychotic features and CSF KYNA levels [n = 55; odds ratio (OR) = 4.9, p = 0.03]. Further, having had a recent manic episode (within the previous year) was also associated with CSF KYNA adjusted for age (n = 34; OR = 4.4, p = 0.03), and the association remained significant when adjusting for a lifetime history of psychotic features (OR = 4.1, p = 0.05). CONCLUSIONS Although the causality needs to be determined, the ability of KYNA to influence dopamine transmission and behavior, along with previous reports showing increased brain levels of the compound in patients with schizophrenia and bipolar disorder, may indicate a possible pathophysiological role of KYNA in the development of manic or psychotic symptoms.
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Affiliation(s)
- Sara K Olsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Schwarcz R, Bruno JP, Muchowski PJ, Wu HQ. Kynurenines in the mammalian brain: when physiology meets pathology. Nat Rev Neurosci 2012; 13:465-77. [PMID: 22678511 DOI: 10.1038/nrn3257] [Citation(s) in RCA: 1003] [Impact Index Per Article: 83.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The essential amino acid tryptophan is not only a precursor of serotonin but is also degraded to several other neuroactive compounds, including kynurenic acid, 3-hydroxykynurenine and quinolinic acid. The synthesis of these metabolites is regulated by an enzymatic cascade, known as the kynurenine pathway, that is tightly controlled by the immune system. Dysregulation of this pathway, resulting in hyper-or hypofunction of active metabolites, is associated with neurodegenerative and other neurological disorders, as well as with psychiatric diseases such as depression and schizophrenia. With recently developed pharmacological agents, it is now possible to restore metabolic equilibrium and envisage novel therapeutic interventions.
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Affiliation(s)
- Robert Schwarcz
- University of Maryland School of Medicine, Baltimore, Maryland 21228, USA. rschwarc@mprc. umaryland.edu
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Sheipouri D, Braidy N, Guillemin GJ. Kynurenine Pathway in Skin Cells: Implications for UV-Induced Skin Damage. Int J Tryptophan Res 2012; 5:15-25. [PMID: 22837645 PMCID: PMC3399400 DOI: 10.4137/ijtr.s9835] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The kynurenine pathway (KP) is the principle route of catabolism of the essential amino acid tryptophan, leading to the production of several neuroactive and immunoregulatory metabolites. Alterations in the KP have been implicated in various neuropsychiatric and neurodegenerative diseases, immunological disorders, and many other diseased states. Although the role of the KP in the skin has been evaluated in small niche fields, limited studies are available regarding the effect of acute ultra violet exposure and the induction of the KP in human skin-derived fibroblasts and keratinocytes. Since UV exposure can illicit an inflammatory component in skin cells, it is highly likely that the KP may be induced in these cells in response to UV exposure. It is also possible that some KP metabolites may act as pro-inflammatory and anti-inflammatory mediators, since the KP is important in immunomodulation.
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Affiliation(s)
- Diba Sheipouri
- University of New South Wales, School of Medical Sciences, Dept of Pharmacology, Sydney, Australia
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Linderholm KR, Skogh E, Olsson SK, Dahl ML, Holtze M, Engberg G, Samuelsson M, Erhardt S. Increased levels of kynurenine and kynurenic acid in the CSF of patients with schizophrenia. Schizophr Bull 2012; 38:426-32. [PMID: 20729465 PMCID: PMC3329991 DOI: 10.1093/schbul/sbq086] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND The kynurenic acid (KYNA) hypothesis for schizophrenia is partly based on studies showing increased brain levels of KYNA in patients. KYNA is an endogenous metabolite of tryptophan (TRP) produced in astrocytes and antagonizes N-methyl-D-aspartate and α7* nicotinic receptors. METHODS The formation of KYNA is determined by the availability of substrate, and hence, we analyzed KYNA and its precursors, kynurenine (KYN) and TRP, in the cerebrospinal fluid (CSF) of patients with schizophrenia. CSF from male patients with schizophrenia on olanzapine treatment (n = 16) was compared with healthy male volunteers (n = 29). RESULTS KYN and KYNA concentrations were higher in patients with schizophrenia (60.7 ± 4.37 nM and 2.03 ± 0.23 nM, respectively) compared with healthy volunteers (28.6 ± 1.44 nM and 1.36 ± 0.08 nM, respectively), whereas TRP did not differ between the groups. In all subjects, KYN positively correlated to KYNA. CONCLUSION Our results demonstrate increased levels of CSF KYN and KYNA in patients with schizophrenia and further support the hypothesis that KYNA is involved in the pathophysiology of schizophrenia.
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Affiliation(s)
- Klas R. Linderholm
- Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Elisabeth Skogh
- Department of Clinical and Experimental Medicine, Section of Psychiatry, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Sara K. Olsson
- Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Marja-Liisa Dahl
- Department of Medical Sciences, Clinical Pharmacology, Uppsala University, Uppsala, Sweden
- Department of Clinical Pharmacology, Karolinska University Hospital, Stockholm, Sweden
| | - Maria Holtze
- Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Göran Engberg
- Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Martin Samuelsson
- Department of Clinical and Experimental Medicine, Section of Psychiatry, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Sophie Erhardt
- Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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Holtze M, Saetre P, Engberg G, Schwieler L, Werge T, Andreassen OA, Hall H, Terenius L, Agartz I, Jönsson EG, Schalling M, Erhardt S. Kynurenine 3-monooxygenase polymorphisms: relevance for kynurenic acid synthesis in patients with schizophrenia and healthy controls. J Psychiatry Neurosci 2012; 37:53-7. [PMID: 21693093 PMCID: PMC3244499 DOI: 10.1503/jpn.100175] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Patients with schizophrenia show increased brain and cerebrospinal fluid (CSF) concentrations of the endogenous N-methyl-D-aspartate receptor antagonist kynurenic acid (KYNA). This compound is an end-metabolite of the kynurenine pathway, and its formation indirectly depends on the activity of kynurenine 3-monooxygenase (KMO), the enzyme converting kynurenine to 3-hydroxykynurenine. METHODS We analyzed the association between KMO gene polymorphisms and CSF concentrations of KYNA in patients with schizophrenia and healthy controls. Fifteen single nucleotide polymorphisms (SNPs) were selected covering KMO and were analyzed in UNPHASED. RESULTS We included 17 patients with schizophrenia and 33 controls in our study. We found an association between a KMO SNP (rs1053230), encoding an amino acid change of potential importance for substrate interaction, and CSF concentrations of KYNA. LIMITATIONS Given the limited sample size, the results are tentative until replication. CONCLUSION Our results suggest that the nonsynonymous KMO SNP rs1053230 influences CSF concentrations of KYNA.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Erik G. Jönsson
- Correspondence to: Dr. E.G. Jönsson, Department of Clinical Neuroscience, HUBIN, Project, Karolinska Institutet and University Hospital, R5:00, SE-171 76 Stockholm, Sweden;
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Subchronic elevation of brain kynurenic acid augments amphetamine-induced locomotor response in mice. J Neural Transm (Vienna) 2011; 119:155-63. [PMID: 21904895 DOI: 10.1007/s00702-011-0706-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Accepted: 08/20/2011] [Indexed: 10/17/2022]
Abstract
The neuromodulating tryptophan metabolite kynurenic acid (KYNA) is increased in the brain of patients with schizophrenia. In the present study we investigate the spontaneous locomotor activity as well as the locomotor response to d-amphetamine [5 mg/kg, administered intraperitoneal (i.p.)] after increasing endogenous levels of brain KYNA in mice by acute (10 mg/kg, i.p., 60 min) or subchronic (100 mg/kg i.p., twice daily for 6 days) pretreatment with the blood-brain crossing precursor, L: -kynurenine. We found that an acute increase in the brain KYNA levels caused increased corner time and percent peripheral activity but did not change the d-amphetamine-induced locomotor response. In contrast, subchronic elevation of KYNA did not change the spontaneous locomotor activity but produced an exaggerated d-amphetamine-induced hyperlocomotion. These results cohere with clinical studies of patients with schizophrenia, where a potentiated DA release associated with exacerbation of positive symptoms has been observed following d-amphetamine administration. Present results further underscore KYNA as a possible mediator of the aberrant dopaminergic neurotransmission seen in schizophrenia.
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Neuronal-immune interactions in mediating stress effects in the etiology and course of schizophrenia: role of the amygdala in developmental co-ordination. Med Hypotheses 2010; 76:54-60. [PMID: 20843610 DOI: 10.1016/j.mehy.2010.08.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 08/10/2010] [Indexed: 11/24/2022]
Abstract
Stress, in its many forms, is long associated with the etiology and course of schizophrenia. The mechanisms mediating the impacts of stress are not fully elucidated. Here it is proposed that stress induced cortisol alters kynurenic acid (KA) and quinolinic acid (QA) in the cortex and amygdala/striatum, respectively. These effects are significantly modulated by BAG-1 (bcl-2 associated anthanogene) and involve ROS, IL-18, and the induction of IDO (indoleamine 2,3-dioxygenase). The kynurenine pathway (KP) products response to stress seems to mediate both prenatal etiology and symptom course in adulthood. It is suggested that the effects of cortisol and quinolinic acid in the amygdala, coupled to an increase in dopamine efflux, mediate amygdala driven developmental changes in the cortex and VTA/N.Accumbens junction. This change in patterned brain activity co-ordinates alterations in motivated behaviour and thought outputs. Such developmental alterations determine changes in sensory-amygdala interactions, readily allowing developmental links to changes in lateral inhibition and pre-pulse inhibition. Decreases in vitamin D3 and melatonin further potentiate such stress induced changes. The likely involvement of glia in mediating increases in the KP products suggests that adaptation to stress is driven by neuronal activity as a form of glia to glia communication.
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Olsson SK, Samuelsson M, Saetre P, Lindström L, Jönsson EG, Nordin C, Engberg G, Erhardt S, Landén M. Elevated levels of kynurenic acid in the cerebrospinal fluid of patients with bipolar disorder. J Psychiatry Neurosci 2010; 35:195-9. [PMID: 20420770 PMCID: PMC2861136 DOI: 10.1503/jpn.090180] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Patients with schizophrenia show elevated brain levels of the neuroactive tryptophan metabolite kynurenic acid (KYNA). This astrocyte-derived mediator acts as a neuroprotectant and modulates sensory gating and cognitive function. We measured the levels of KYNA in the cerebrospinal fluid (CSF) of patients with bipolar disorder and healthy volunteers to investigate the putative involvement of KYNA in bipolar disorder. METHODS We obtained CSF by lumbar puncture from 23 healthy men and 31 euthymic men with bipolar disorder. We analyzed the samples using high-performance liquid chromatography. RESULTS Patients with bipolar disorder had increased levels of KYNA in their CSF compared with healthy volunteers (1.71 nM, standard error of the mean [SEM] 0.13 v. 1.13 nM, SEM 0.09; p = 0.002. The levels of KYNA were positively correlated with age among bipolar patients but not healthy volunteers. LIMITATIONS The influence of ongoing drug treatment among patients cannot be ruled out. We conducted our study during the euthymic phase of the disease. CONCLUSION Brain KYNA levels are increased in euthymic men with bipolar disorder. In addition, KYNA levels increased with age in these patients. These findings indicate shared mechanisms between bipolar disorder and schizophrenia. Elevated levels of brain KYNA may provide further insight to the pathophysiology and progression of bipolar disorder.
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Affiliation(s)
| | | | | | | | | | | | | | - Sophie Erhardt
- Correspondence to: Dr. S. Erhardt, Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden; fax 46 8 31 06 22;
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Linderholm K, Powell S, Olsson E, Holtze M, Snodgrass R, Erhardt S. Role of the NMDA-receptor in Prepulse Inhibition in the Rat. Int J Tryptophan Res 2010; 3:1-12. [PMID: 22084584 PMCID: PMC3195246 DOI: 10.4137/ijtr.s4260] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kynurenic acid (KYNA) is an endogenous metabolite of tryptophan. Studies have revealed increased brain KYNA levels in patients with schizophrenia. Prepulse inhibition (PPI) is a behavioral model for sensorimotor gating and found to be reduced in schizophrenia. Previous studies have shown that pharmacologically elevated brain KYNA levels disrupt PPI in the rat. The aim of the present study was to investigate the receptor(s) involved in this effect. Rats were treated with different drugs selectively blocking each of the sites that KYNA antagonizes, namely the glutamate recognition site of the N-methyl-D-aspartate receptor (NMDAR), the α7* nicotinic acetylcholine receptor (α7nAChR) and the glycine site of the NMDAR. Kynurenine (200 mg/kg) was given to replicate the effects of increased levels of KYNA on PPI. In order to block the glutamate recognition site of the NMDAR, CGS 19755 (10 mg/kg) or SDZ 220–581 (2.5 mg/kg) were administered and to antagonize the α7nAChR methyllycaconitine (MLA; 6 mg/kg) was given. L-701,324 (1 and 4 mg/kg) or 4-Chloro-kynurenine (4-Cl-KYN; 25, 50 and 100 mg/kg), a drug in situ converted to 7-Chloro-kynurenic acid, were used to block the glycine-site of the NMDAR. Administration of SDZ 220-581 or CGS 19755 was associated with a robust reduction in PPI, whereas L-701,324, 4-Cl-KYN or MLA failed to alter PPI. Kynurenine increased brain KYNA levels 5-fold and tended to decrease PPI. The present study suggests that neither antagonism of the glycine-site of the NMDA receptor nor antagonism of the α7nAChR disrupts PPI, rather with regard to the effects of KYNA, blockade of the glutamate recognition-site is necessary to reduce PPI.
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Affiliation(s)
- Klas Linderholm
- Dept. of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Zmarowski A, Wu HQ, Brooks JM, Potter MC, Pellicciari R, Schwarcz R, Bruno JP. Astrocyte-derived kynurenic acid modulates basal and evoked cortical acetylcholine release. Eur J Neurosci 2009; 29:529-38. [PMID: 19187269 DOI: 10.1111/j.1460-9568.2008.06594.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We tested the hypothesis that fluctuations in the levels of kynurenic acid (KYNA), an endogenous antagonist of the alpha7 nicotinic acetylcholine (ACh) receptor, modulate extracellular ACh levels in the medial prefrontal cortex in rats. Decreases in cortical KYNA levels were achieved by local perfusion of S-ESBA, a selective inhibitor of the astrocytic enzyme kynurenine aminotransferase II (KAT II), which catalyses the formation of KYNA from its precursor L-kynurenine. At 5 mm, S-ESBA caused a 30% reduction in extracellular KYNA levels, which was accompanied by a two-threefold increase in basal cortical ACh levels. Co-perfusion of KYNA in the endogenous range (100 nm), which by itself tended to reduce basal ACh levels, blocked the ability of S-ESBA to raise extracellular ACh levels. KYNA perfusion (100 nm) also prevented the evoked ACh release caused by d-amphetamine (2.0 mg/kg). This effect was duplicated by the systemic administration of kynurenine (50 mg/kg), which resulted in a significant increase in cortical KYNA formation. Jointly, these data indicate that astrocytes, by producing and releasing KYNA, have the ability to modulate cortical cholinergic neurotransmission under both basal and stimulated conditions. As cortical KYNA levels are elevated in individuals with schizophrenia, and in light of the established role of cortical ACh in executive functions, our findings suggest that drugs capable of attenuating the production of KYNA may be of benefit in the treatment of cognitive deficits in schizophrenia.
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Affiliation(s)
- A Zmarowski
- Department of Psychology and Neuroscience, The Ohio State University, Columbus, OH 43210, USA
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Mok MHS, Fricker AC, Weil A, Kew JNC. Electrophysiological characterisation of the actions of kynurenic acid at ligand-gated ion channels. Neuropharmacology 2009; 57:242-9. [PMID: 19523966 DOI: 10.1016/j.neuropharm.2009.06.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 05/22/2009] [Accepted: 06/01/2009] [Indexed: 10/20/2022]
Abstract
To better understand the effects of the tryptophan metabolite kynurenic acid (kynA) in the brain, we characterised its actions at five ligand-gated ion channels: NMDA, AMPA, GABA(A), glycine and alpha7 nicotinic acetylcholine receptors. Using whole-cell patch-clamp recordings, we found that kynA was a more potent antagonist at human NR1a/NR2A compared with NR1a/NR2B receptors (IC(50): 158 muM and 681 muM, respectively; in 30 muM glycine). KynA inhibited AMPA-evoked currents to a similar degree in cultured hippocampal neurons and a human GluR2(flip/unedited) cell line (IC(50): 433 and 596 muM, respectively) and at higher concentrations, kynA also inhibited the strychnine-sensitive glycine receptor ( approximately 35% inhibition by 3 mM kynA). Interestingly, kynA inhibited the peak amplitude (IC(50): 2.9 mM for 10 muM GABA) and slowed the decay kinetics of GABA-evoked currents in cultured neurons. In contrast, we found that kynA (1-3 mM) had no effect on ACh-evoked, methyllycaconitine (MLA)-sensitive currents in a human alpha7 nicotinic receptor (nAChR) cell line, rat hippocampal neurons in primary culture or CA1 stratum radiatum interneurons in rat brain slices. However, DMSO (>1%) did inhibit alpha7 nAChR-mediated currents. In conclusion, kynA is an antagonist at NMDA, AMPA and glycine receptors and a modulator of GABA(A) receptors, but we find no evidence for any effect of kynA at the alpha7 nAChR.
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Affiliation(s)
- M H Selina Mok
- Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, Essex CM19 5AW, United Kingdom.
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Nicotinic receptors differentially modulate the induction and expression of behavioral sensitization to methylphenidate in rats. Psychopharmacology (Berl) 2009; 204:551-62. [PMID: 19229521 PMCID: PMC2682633 DOI: 10.1007/s00213-009-1487-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 01/31/2009] [Indexed: 12/25/2022]
Abstract
RATIONALE Nicotinic acetylcholine receptors (nAChRs) regulate sensitization to stimulant drugs such as d-amphetamine and cocaine. OBJECTIVES The current study determined if nAChRs modulate the induction and/or expression of behavioral sensitization to high methylphenidate doses. METHODS In experiment 1, rats received saline or mecamylamine (3 mg/kg, sc), followed by saline or methylphenidate (5.6 or 10 mg/kg, sc) during 10 daily sessions; the effect of methylphenidate (1-17 mg/kg, sc) alone was determined 14 days later. In experiment 2, rats received saline or dihydro-beta-erythroidine (DHbetaE; 3 mg/kg, sc), followed by saline or 5.6 mg/kg of methylphenidate. In experiment 3, rats received saline or methylphenidate (5.6 or 10 mg/kg, sc) alone for 10 days; the effect of acute mecamylamine (3 mg/kg, sc) on the response to methylphenidate (1-17 mg/kg, sc) was determined 14 days later. Locomotor activity, sniffing, rearing, grooming, and stereotypy ratings were dependent measures. RESULTS Methylphenidate produced dose-dependent increases in locomotor activity, sniffing, and stereotypy on day 1 and these effects were enhanced on day 10, indicative of sensitization. Mecamylamine attenuated methylphenidate-induced stereotypy only on day 1, but reduced locomotor activity, sniffing, rearing, and stereotypy on day 10 and during the methylphenidate challenge phase; similar results were obtained with DHbetaE. However, acute mecamylamine did not alter the effects of the methylphenidate challenge following the induction of sensitization to methylphenidate alone. CONCLUSIONS Although nAChRs do not appear to regulate the expression of methylphenidate-induced behavioral sensitization, inhibition of high-affinity beta2 subunit nAChRs attenuates the induction of behavioral sensitization to high doses of methylphenidate.
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Elevated levels of kynurenic acid change the dopaminergic response to amphetamine: implications for schizophrenia. Int J Neuropsychopharmacol 2009; 12:501-12. [PMID: 18796185 DOI: 10.1017/s1461145708009383] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kynurenic acid (KYNA) is an endogenous compound implicated in the pathophysiology of schizophrenia. This tryptophan metabolite antagonizes both the N-methyl-D-aspartate (NMDA) receptors and the nicotinic alpha7* receptors at micromolar concentrations. In the present study the effects of amphetamine on dopamine (DA) release in the nucleus accumbens and on firing of DA neurons in the ventral tegmental area (VTA) were investigated in rats treated with kynurenine, the precursor of KYNA, in order to elevate brain KYNA levels. In rats subchronically treated with kynurenine (90 mg/kg x d for 6 d via osmotic minipumps, resulting in a 2-fold increase in whole-brain KYNA), the amphetamine-induced (2 mg/kg i.p.) increase in accumbal DA release was clearly enhanced compared to controls. Furthermore, subchronic treatment with kynurenine reduced the inhibitory action of amphetamine (0.2-25.6 mg/kg i.v.) on firing rate and burst firing activity of VTA DA neurons. A single dose of kynurenine (5 mg/kg s.c., 60 min, resulting in a 3-fold increase in whole-brain KYNA) did not alter the amphetamine-induced effects on DA neurotransmission compared to control rats. Present data are in agreement with the increased striatal DA release by amphetamine as observed by brain-imaging studies in patients with schizophrenia. Thus, subchronic elevation of rat brain KYNA, may rationally serve as an animal model similar to a pathophysiological condition of schizophrenia. It is proposed that the reduced responsivity of VTA DA neurons to the inhibitory action of amphetamine observed in rats with subchronically elevated KYNA levels may partly account for the increase in terminal DA release.
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Erhardt S, Olsson SK, Engberg G. Pharmacological manipulation of kynurenic acid: potential in the treatment of psychiatric disorders. CNS Drugs 2009; 23:91-101. [PMID: 19173370 DOI: 10.2165/00023210-200923020-00001] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The kynurenine pathway constitutes the main route of tryptophan degradation and generates the production of several neuroactive compounds; quinolinic acid is an excitotoxic NMDA receptor agonist, 3-hydroxykynurenine is a free-radical generator and kynurenic acid (KYNA) is an antagonist at glutamate and nicotinic receptors. In low micromolar concentrations, KYNA blocks the glycine site of the NMDA receptor and the nicotinic alpha(7) acetylcholine receptor. Knowledge regarding kynurenine metabolites and their involvement in neurophysiological processes has increased dramatically in recent years. In particular, endogenous KYNA appears to tightly control firing of midbrain dopamine neurons and to be involved in cognitive functions. Thus, decreased endogenous levels of rat brain KYNA have been found to reduce firing of these neurons, and mice with a targeted deletion of kynurenine aminotransferase II display low endogenous brain KYNA levels concomitant with an increased performance in cognitive tests. It is also suggested that kynurenines participate in the pathophysiology of psychiatric disorders. Thus, elevated levels of KYNA have been found in the CSF as well as in the post-mortem brain of patients with schizophrenia. Advantages in understanding how kynurenines can be pharmacologically manipulated may provide new possibilities in the treatment of psychiatric disorders, such as schizophrenia.
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Affiliation(s)
- Sophie Erhardt
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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36
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Induction of the kynurenine pathway by neurotropic influenza a virus infection. J Neurosci Res 2008; 86:3674-83. [DOI: 10.1002/jnr.21799] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Current world literature. Trauma and rehabilitation. Curr Opin Neurol 2008; 21:762-4. [PMID: 18989123 DOI: 10.1097/wco.0b013e32831cbb85] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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