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Bertollo AG, Mingoti MED, Ignácio ZM. Neurobiological mechanisms in the kynurenine pathway and major depressive disorder. Rev Neurosci 2024:revneuro-2024-0065. [PMID: 39245854 DOI: 10.1515/revneuro-2024-0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 08/20/2024] [Indexed: 09/10/2024]
Abstract
Major depressive disorder (MDD) is a prevalent psychiatric disorder that has damage to people's quality of life. Tryptophan is the precursor to serotonin, a critical neurotransmitter in mood modulation. In mammals, most free tryptophan is degraded by the kynurenine pathway (KP), resulting in a range of metabolites involved in inflammation, immune response, and neurotransmission. The imbalance between quinolinic acid (QA), a toxic metabolite, and kynurenic acid (KynA), a protective metabolite, is a relevant phenomenon involved in the pathophysiology of MDD. Proinflammatory cytokines increase the activity of the enzyme indoleamine 2,3-dioxygenase (IDO), leading to the degradation of tryptophan in the KP and an increase in the release of QA. IDO activates proinflammatory genes, potentiating neuroinflammation and deregulating other physiological mechanisms related to chronic stress and MDD. This review highlights the physiological mechanisms involved with stress and MDD, which are underlying an imbalance of the KP and discuss potential therapeutic targets.
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Affiliation(s)
- Amanda Gollo Bertollo
- Laboratory of Physiology, Pharmacology and Psychopathology, Graduate Program in Biomedical Sciences, Federal University of Fronteira Sul, Chapecó, SC, Brazil
| | - Maiqueli Eduarda Dama Mingoti
- Laboratory of Physiology, Pharmacology and Psychopathology, Graduate Program in Biomedical Sciences, Federal University of Fronteira Sul, Chapecó, SC, Brazil
| | - Zuleide Maria Ignácio
- Laboratory of Physiology, Pharmacology and Psychopathology, Graduate Program in Biomedical Sciences, Federal University of Fronteira Sul, Chapecó, SC, Brazil
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2
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Stone TW, Williams RO. Tryptophan metabolism as a 'reflex' feature of neuroimmune communication: Sensor and effector functions for the indoleamine-2, 3-dioxygenase kynurenine pathway. J Neurochem 2024; 168:3333-3357. [PMID: 38102897 DOI: 10.1111/jnc.16015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/16/2023] [Accepted: 11/08/2023] [Indexed: 12/17/2023]
Abstract
Although the central nervous system (CNS) and immune system were regarded as independent entities, it is now clear that immune system cells can influence the CNS, and neuroglial activity influences the immune system. Despite the many clinical implications for this 'neuroimmune interface', its detailed operation at the molecular level remains unclear. This narrative review focuses on the metabolism of tryptophan along the kynurenine pathway, since its products have critical actions in both the nervous and immune systems, placing it in a unique position to influence neuroimmune communication. In particular, since the kynurenine pathway is activated by pro-inflammatory mediators, it is proposed that physical and psychological stressors are the stimuli of an organismal protective reflex, with kynurenine metabolites as the effector arm co-ordinating protective neural and immune system responses. After a brief review of the neuroimmune interface, the general perception of tryptophan metabolism along the kynurenine pathway is expanded to emphasize this environmentally driven perspective. The initial enzymes in the kynurenine pathway include indoleamine-2,3-dioxygenase (IDO1), which is induced by tissue damage, inflammatory mediators or microbial products, and tryptophan-2,3-dioxygenase (TDO), which is induced by stress-induced glucocorticoids. In the immune system, kynurenic acid modulates leucocyte differentiation, inflammatory balance and immune tolerance by activating aryl hydrocarbon receptors and modulates pain via the GPR35 protein. In the CNS, quinolinic acid activates N-methyl-D-aspartate (NMDA)-sensitive glutamate receptors, whereas kynurenic acid is an antagonist: the balance between glutamate, quinolinic acid and kynurenic acid is a significant regulator of CNS function and plasticity. The concept of kynurenine and its metabolites as mediators of a reflex coordinated protection against stress helps to understand the variety and breadth of their activity. It should also help to understand the pathological origin of some psychiatric and neurodegenerative diseases involving the immune system and CNS, facilitating the development of new pharmacological strategies for treatment.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, UK
| | - Richard O Williams
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, UK
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Stone TW, Darlington LG, Badawy AAB, Williams RO. The Complex World of Kynurenic Acid: Reflections on Biological Issues and Therapeutic Strategy. Int J Mol Sci 2024; 25:9040. [PMID: 39201726 PMCID: PMC11354734 DOI: 10.3390/ijms25169040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Revised: 08/13/2024] [Accepted: 08/14/2024] [Indexed: 09/03/2024] Open
Abstract
It has been unequivocally established that kynurenic acid has a number of actions in a variety of cells and tissues, raising, in principle, the possibility of targeting its generation, metabolism or sites of action to manipulate those effects to a beneficial therapeutic end. However, many basic aspects of the biology of kynurenic acid remain unclear, potentially leading to some confusion and misinterpretations of data. They include questions of the source, generation, targets, enzyme expression, endogenous concentrations and sites of action. This essay is intended to raise and discuss many of these aspects as a source of reference for more balanced discussion. Those issues are followed by examples of situations in which modulating and correcting kynurenic acid production or activity could bring significant therapeutic benefit, including neurological and psychiatric conditions, inflammatory diseases and cell protection. More information is required to obtain a clear overall view of the pharmacological environment relevant to kynurenic acid, especially with respect to the active concentrations of kynurenine metabolites in vivo and changed levels in disease. The data and ideas presented here should permit a greater confidence in appreciating the sites of action and interaction of kynurenic acid under different local conditions and pathologies, enhancing our understanding of kynurenic acid itself and the many clinical conditions in which manipulating its pharmacology could be of clinical value.
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Affiliation(s)
- Trevor W. Stone
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK;
| | - L. Gail Darlington
- Worthing Hospital, University Hospitals Sussex NHS Foundation Trust, Worthing BN11 2DH, UK
| | - Abdulla A.-B. Badawy
- Formerly School of Health Sciences, Cardiff Metropolitan University, Cardiff CF5 2YB, UK
| | - Richard O. Williams
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK;
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Murakami Y, Imamura Y, Kasahara Y, Yoshida C, Momono Y, Fang K, Sakai D, Konishi Y, Nishiyama T. Maternal Inflammation with Elevated Kynurenine Metabolites Is Related to the Risk of Abnormal Brain Development and Behavioral Changes in Autism Spectrum Disorder. Cells 2023; 12:1087. [PMID: 37048160 PMCID: PMC10093447 DOI: 10.3390/cells12071087] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/27/2023] [Accepted: 03/31/2023] [Indexed: 04/14/2023] Open
Abstract
Several studies show that genetic and environmental factors contribute to the onset and progression of neurodevelopmental disorders. Maternal immune activation (MIA) during gestation is considered one of the major environmental factors driving this process. The kynurenine pathway (KP) is a major route of the essential amino acid L-tryptophan (Trp) catabolism in mammalian cells. Activation of the KP following neuro-inflammation can generate various endogenous neuroactive metabolites that may impact brain functions and behaviors. Additionally, neurotoxic metabolites and excitotoxicity cause long-term changes in the trophic support, glutamatergic system, and synaptic function following KP activation. Therefore, investigating the role of KP metabolites during neurodevelopment will likely promote further understanding of additional pathophysiology of neurodevelopmental disorders, including autism spectrum disorder (ASD). In this review, we describe the changes in KP metabolism in the brain during pregnancy and represent how maternal inflammation and genetic factors influence the KP during development. We overview the patients with ASD clinical data and animal models designed to verify the role of perinatal KP elevation in long-lasting biochemical, neuropathological, and behavioral deficits later in life. Our review will help shed light on new therapeutic strategies and interventions targeting the KP for neurodevelopmental disorders.
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Affiliation(s)
- Yuki Murakami
- Department of Hygiene and Public Health, Kansai Medical University, Hirakata 573-1010, Japan
| | - Yukio Imamura
- Department of Architecture and Architectual Systems Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8530, Japan
- Department of Traumatology and Acute Critical Medicine, Graduate School of Medicine/Faculty of Medicine, Osaka University, Suita 565-0871, Japan
| | - Yoshiyuki Kasahara
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Chihiro Yoshida
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Yuta Momono
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Ke Fang
- Department of Hygiene and Public Health, Kansai Medical University, Hirakata 573-1010, Japan
| | - Daisuke Sakai
- Department of Biology, Kanazawa Medical University, Kanazawa 920-0293, Japan
| | - Yukuo Konishi
- Center for Baby Science, Doshisha University, Kyotanabe 619-0225, Japan
- Healthcare and Medical Data Multi-Level Integration Platform Group, RIKEN Medical Sciences Innovation Hub Program, Yokohama 230-0045, Japan
| | - Toshimasa Nishiyama
- Department of Hygiene and Public Health, Kansai Medical University, Hirakata 573-1010, Japan
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Stone TW, Clanchy FIL, Huang YS, Chiang NY, Darlington LG, Williams RO. An integrated cytokine and kynurenine network as the basis of neuroimmune communication. Front Neurosci 2022; 16:1002004. [PMID: 36507331 PMCID: PMC9729788 DOI: 10.3389/fnins.2022.1002004] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 10/31/2022] [Indexed: 11/25/2022] Open
Abstract
Two of the molecular families closely associated with mediating communication between the brain and immune system are cytokines and the kynurenine metabolites of tryptophan. Both groups regulate neuron and glial activity in the central nervous system (CNS) and leukocyte function in the immune system, although neither group alone completely explains neuroimmune function, disease occurrence or severity. This essay suggests that the two families perform complementary functions generating an integrated network. The kynurenine pathway determines overall neuronal excitability and plasticity by modulating glutamate receptors and GPR35 activity across the CNS, and regulates general features of immune cell status, surveillance and tolerance which often involves the Aryl Hydrocarbon Receptor (AHR). Equally, cytokines and chemokines define and regulate specific populations of neurons, glia or immune system leukocytes, generating more specific responses within restricted CNS regions or leukocyte populations. In addition, as there is a much larger variety of these compounds, their homing properties enable the superimposition of dynamic variations of cell activity upon local, spatially limited, cell populations. This would in principle allow the targeting of potential treatments to restricted regions of the CNS. The proposed synergistic interface of 'tonic' kynurenine pathway affecting baseline activity and the superimposed 'phasic' cytokine system would constitute an integrated network explaining some features of neuroimmune communication. The concept would broaden the scope for the development of new treatments for disorders involving both the CNS and immune systems, with safer and more effective agents targeted to specific CNS regions.
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Affiliation(s)
- Trevor W. Stone
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom,*Correspondence: Trevor W. Stone,
| | - Felix I. L. Clanchy
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Yi-Shu Huang
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Nien-Yi Chiang
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - L. Gail Darlington
- Department of Internal Medicine, Ashtead Hospital, Ashtead, United Kingdom
| | - Richard O. Williams
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
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Tanaka M, Spekker E, Szabó Á, Polyák H, Vécsei L. Modelling the neurodevelopmental pathogenesis in neuropsychiatric disorders. Bioactive kynurenines and their analogues as neuroprotective agents-in celebration of 80th birthday of Professor Peter Riederer. J Neural Transm (Vienna) 2022; 129:627-642. [PMID: 35624406 DOI: 10.1007/s00702-022-02513-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 05/05/2022] [Indexed: 02/06/2023]
Abstract
Following introduction of the monoamine oxidase type B inhibitor selegiline for the treatment of Parkinson's disease (PD), discovery of the action mechanism of Alzheimer's disease-modifying agent memantine, the role of iron in PD, and the loss of electron transport chain complex I in PD, and development of the concept of clinical neuroprotection, Peter Riederer launched one of the most challenging research project neurodevelopmental aspects of neuropsychiatric disorders. The neurodevelopmental theory holds that a disruption of normal brain development in utero or during early life underlies the subsequent emergence of neuropsychiatric symptoms during later life. Indeed, the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition and the International Classification of Diseases, 11th Revision categorize autism spectrum disorder and attention deficit hyperactivity disorder in neurodevelopmental disorders (NDDs). More and more evidence, especially from preclinical studies, is revealing that neurodevelopmental pathology is not limited to the diagnostic class above, but also contributes to the development of other psychiatric disorders such as schizophrenia, bipolar disorder, and obsessive-compulsive disorder as well as neurodegenerative diseases such as PD and Huntington's disease. Preclinical animal research is taking a lead in understanding the pathomechanisms of NDDs, searching for novel targets, and developing new neuroprotective agents against NDDs. This narrative review discusses emerging evidence of the neurodevelopmental etiology of neuropsychiatric disorders, recent advances in modelling neurodevelopmental pathogenesis, potential strategies of clinical neuroprotection using novel kynurenine metabolites and analogues, and future research direction for NDDs.
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Affiliation(s)
- Masaru Tanaka
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, 6725, Szeged, Hungary
| | - Eleonóra Spekker
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, 6725, Szeged, Hungary
| | - Ágnes Szabó
- Department of Neurology, Albert Szent-György Medical School, University of Szeged, Semmelweis u. 6, 6725, Szeged, Hungary
| | - Helga Polyák
- Department of Neurology, Albert Szent-György Medical School, University of Szeged, Semmelweis u. 6, 6725, Szeged, Hungary
| | - László Vécsei
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, 6725, Szeged, Hungary. .,Department of Neurology, Albert Szent-György Medical School, University of Szeged, Semmelweis u. 6, 6725, Szeged, Hungary.
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Notarangelo FM, Schwarcz R. A single prenatal lipopolysaccharide injection has acute, but not long-lasting, effects on cerebral kynurenine pathway metabolism in mice. Eur J Neurosci 2021; 54:5968-5981. [PMID: 34363411 DOI: 10.1111/ejn.15416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/26/2021] [Accepted: 08/03/2021] [Indexed: 11/28/2022]
Abstract
In rodents, a single injection of lipopolysaccharide (LPS) during gestation causes chemical and functional abnormalities in the offspring. These effects may involve changes in the kynurenine pathway (KP) of tryptophan degradation and may provide insights into the pathophysiology of psychiatric diseases. Using CD1 mice, we examined acute and long-term effects of prenatal LPS treatment on the levels of kynurenine and its neuroactive downstream products kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK) and quinolinic acid. To this end, LPS (100 μg/kg, i.p.) was administered on gestational day 15, and KP metabolites were measured 4 and 24 h later or in adulthood. After 4 h, kynurenine, KYNA and 3-HK levels were elevated in the fetal brain, 3-HK and KYNA levels were increased in the maternal plasma, and kynurenine was increased in the maternal brain, whereas no changes were seen in the placenta. These effects were less prominent after 24 h, and prenatal LPS did not affect the basal levels of KP metabolites in the forebrain of adult animals. In addition, a second LPS injection (1 mg/kg) in adulthood in the offspring of prenatally saline- and LPS-treated mice caused a similar elevation in 3-HK levels in both groups after 24 h, but the effect was significantly more pronounced in male mice. Thus, acute immune activation during pregnancy has only short-lasting effects on KP metabolism and does not cause cerebral KP metabolites to be disproportionally affected by a second immune challenge in adulthood. However, prenatal KYNA elevations still contribute to functional abnormalities in the offspring.
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Affiliation(s)
- Francesca M Notarangelo
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Prenatal stress-induced disruptions in microbial and host tryptophan metabolism and transport. Behav Brain Res 2021; 414:113471. [PMID: 34280459 DOI: 10.1016/j.bbr.2021.113471] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/22/2021] [Accepted: 07/14/2021] [Indexed: 12/19/2022]
Abstract
The aromatic amino acid tryptophan (Trp) is a precursor for multiple metabolites that can steer proper immune and neurodevelopment as well as social behavior in later life. Dysregulation in the Trp metabolic pathways and abundance of Trp or its derivatives, including indoles, kynurenine (Kyn), and particularly serotonin, has been associated with behavioral deficits and neuropsychiatric disorders including autism spectrum disorders (ASD) and schizophrenia. Previously, we have shown that prenatal stress (PNS) alters placental Trp and serotonin, and reduces Trp-metabolizing members of the maternal colonic microbiota. Given that PNS also results in alterations in offspring neurodevelopment, behavior and immune function, we hypothesized that PNS affects Trp metabolism and transport in both the maternal and fetal compartments, and that these alterations continue into adolescence. We surmised that this is due to reductions in Trp-metabolizing microbes that would otherwise reduce the Trp pool under normal metabolic conditions. To test this, pregnant mice were exposed to a restraint stressor and gene expression of enzymes involved in Trp and serotonin metabolism were measured. Specifically, tryptophan 2,3-dioxygenase, aryl hydrocarbon receptor, and solute carrier proteins, were altered due to PNS both prenatally and postnatally. Additionally, Parasutterella and Bifidobacterium, which metabolize Trp in the gut, were reduced in both the dam and the offspring. Together, the reductions of Trp-associated microbes and concomitant dysregulation in Trp metabolic machinery in dam and offspring suggest that PNS-induced Trp metabolic dysfunction may mediate aberrant fetal neurodevelopment.
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Murakami Y, Imamura Y, Kasahara Y, Yoshida C, Momono Y, Fang K, Nishiyama T, Sakai D, Konishi Y. The Effects of Maternal Interleukin-17A on Social Behavior, Cognitive Function, and Depression-Like Behavior in Mice with Altered Kynurenine Metabolites. Int J Tryptophan Res 2021; 14:11786469211026639. [PMID: 34262289 PMCID: PMC8243115 DOI: 10.1177/11786469211026639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 05/31/2021] [Indexed: 01/03/2023] Open
Abstract
Viral infection and chronic maternal inflammation during pregnancy are correlated
with a higher prevalence of autism spectrum disorder (ASD). However, the
pathoetiology of ASD is not fully understood; moreover, the key molecules that
can cross the placenta following maternal inflammation and contribute to the
development of ASD have not been identified. Recently, the pro-inflammatory
cytokine, interleukin-17A (IL-17A) was identified as a potential mediator of
these effects. To investigate the impact of maternal IL-17A on offspring,
C57BL/6J dams were injected with IL-17A-expressing plasmids via
the tail vein on embryonic day 12.5 (E12.5), and maternal IL-17A was expressed
continuously throughout pregnancy. By adulthood, IL-17A-injected offspring
exhibited behavioral abnormalities, including social and cognitive defects.
Additionally, maternal IL-17A promoted metabolism of the essential amino acid
tryptophan, which produces several neuroactive compounds and may affect fetal
neurodevelopment. We observed significantly increased levels of kynurenine in
maternal serum and fetal plasma. Thus, we investigated the effects of high
maternal concentration of kynurenine on offspring by continuously administering
mouse dams with kynurenine from E12.5 during gestation. Obviously, maternal
kynurenine administration rapidly increased kynurenine levels in the fetal
plasma and brain, pointing to the ability of kynurenine to cross the placenta
and change the KP metabolites which are affected as neuroactive compounds in the
fetal brain. Notably, the offspring of kynurenine-injected mice exhibited
behavioral abnormalities similar to those observed in offspring of
IL-17A-conditioned mice. Several tryptophan metabolites were significantly
altered in the prefrontal cortex of the IL-17A-conditioned and
kynurenine-injected adult mice, but not in the hippocampus. Even though we
cannot exclude the possibility or other molecules being related to ASD
pathogenesis and the presence of a much lower degree of pathway activation, our
results suggest that increased kynurenine following maternal inflammation may be
a key factor in changing the balance of KP metabolites in fetal brain during
neuronal development and represents a therapeutic target for
inflammation-induced ASD-like phenotypes.
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Affiliation(s)
- Yuki Murakami
- Department of Hygiene and Public Health, Kansai Medical University, Osaka, Japan
| | - Yukio Imamura
- Organization for Research Initiatives and Development, Doshisha University, Kyoto, Japan.,Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yoshiyuki Kasahara
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Chihiro Yoshida
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yuta Momono
- Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Ke Fang
- Department of Hygiene and Public Health, Kansai Medical University, Osaka, Japan
| | - Toshimasa Nishiyama
- Department of Hygiene and Public Health, Kansai Medical University, Osaka, Japan
| | - Daisuke Sakai
- Department of Biology, Kanazawa Medical University, Ishikawa, Japan
| | - Yukuo Konishi
- Center for Baby Science, Doshisha University, Kyoto, Japan.,Healthcare and Medical Data Multi-level Integration Platform Group, RIKEN Medical Sciences Innovation Hub Program, Kanagawa, Japan
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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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Cohen Kadosh K, Muhardi L, Parikh P, Basso M, Jan Mohamed HJ, Prawitasari T, Samuel F, Ma G, Geurts JMW. Nutritional Support of Neurodevelopment and Cognitive Function in Infants and Young Children-An Update and Novel Insights. Nutrients 2021; 13:nu13010199. [PMID: 33435231 PMCID: PMC7828103 DOI: 10.3390/nu13010199] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Proper nutrition is crucial for normal brain and neurocognitive development. Failure to optimize neurodevelopment early in life can have profound long-term implications for both mental health and quality of life. Although the first 1000 days of life represent the most critical period of neurodevelopment, the central and peripheral nervous systems continue to develop and change throughout life. All this time, development and functioning depend on many factors, including adequate nutrition. In this review, we outline the role of nutrients in cognitive, emotional, and neural development in infants and young children with special attention to the emerging roles of polar lipids and high quality (available) protein. Furthermore, we discuss the dynamic nature of the gut-brain axis and the importance of microbial diversity in relation to a variety of outcomes, including brain maturation/function and behavior are discussed. Finally, the promising therapeutic potential of psychobiotics to modify gut microbial ecology in order to improve mental well-being is presented. Here, we show that the individual contribution of nutrients, their interaction with other micro- and macronutrients and the way in which they are organized in the food matrix are of crucial importance for normal neurocognitive development.
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Affiliation(s)
- Kathrin Cohen Kadosh
- School of Psychology, University of Surrey, Guildford GU2 7XH, UK; (K.C.K.); (M.B.)
| | - Leilani Muhardi
- FrieslandCampina AMEA, Singapore 039190, Singapore; (L.M.); (P.P.)
| | - Panam Parikh
- FrieslandCampina AMEA, Singapore 039190, Singapore; (L.M.); (P.P.)
| | - Melissa Basso
- School of Psychology, University of Surrey, Guildford GU2 7XH, UK; (K.C.K.); (M.B.)
- Department of General Psychology, University of Padova, 35131 Padova, Italy
| | - Hamid Jan Jan Mohamed
- Nutrition and Dietetics Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Malaysia;
| | - Titis Prawitasari
- Nutrition and Metabolic Diseases Working Group, Indonesian Pediatric Society, Jakarta 10310, Indonesia;
- Department of Pediatrics, Faculty of Medicine, Universitas Indonesia, Dr. Cipto Mangunkusomo National Referral Hospital Jakarta, Jakarta 10430, Indonesia
| | - Folake Samuel
- Department of Human Nutrition, University of Ibadan, Ibadan 200284, Nigeria;
| | - Guansheng Ma
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, 38 Xue Yuan Road, Haidian District, Beijing 100191, China;
- Laboratory of Toxicological Research and Risk assessment for Food Safety, Peking University, 38 Xue Yuan Road, Haidian District, Beijing 100191, China
| | - Jan M. W. Geurts
- FrieslandCampina, 3818 LE Amersfoort, The Netherlands
- Correspondence: ; Tel.: +31-6-53310499
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Wright CJ, Rentschler KM, Wagner NTJ, Lewis AM, Beggiato S, Pocivavsek A. Time of Day-Dependent Alterations in Hippocampal Kynurenic Acid, Glutamate, and GABA in Adult Rats Exposed to Elevated Kynurenic Acid During Neurodevelopment. Front Psychiatry 2021; 12:734984. [PMID: 34603109 PMCID: PMC8484637 DOI: 10.3389/fpsyt.2021.734984] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/23/2021] [Indexed: 01/09/2023] Open
Abstract
Hypofunction of glutamatergic signaling is causally linked to neurodevelopmental disorders, including psychotic disorders like schizophrenia and bipolar disorder. Kynurenic acid (KYNA) has been found to be elevated in postmortem brain tissue and cerebrospinal fluid of patients with psychotic illnesses and may be involved in the hypoglutamatergia and cognitive dysfunction experienced by these patients. As insults during the prenatal period are hypothesized to be linked to the pathophysiology of psychotic disorders, we presently utilized the embryonic kynurenine (EKyn) paradigm to induce a prenatal hit. Pregnant Wistar dams were fed chow laced with kynurenine to stimulate fetal brain KYNA elevation from embryonic day 15 to embryonic day 22. Control dams (ECon) were fed unlaced chow. Plasma and hippocampal tissue from young adult (postnatal day 56) ECon and EKyn male and female offspring were collected at the beginning of the light (Zeitgeber time, ZT 0) and dark (ZT 12) phases to assess kynurenine pathway metabolites. Hippocampal tissue was also collected at ZT 6 and ZT 18. In separate animals, in vivo microdialysis was conducted in the dorsal hippocampus to assess extracellular KYNA, glutamate, and γ-aminobutyric acid (GABA). Biochemical analyses revealed no changes in peripheral metabolites, yet hippocampal tissue KYNA levels were significantly impacted by EKyn treatment, and increased in male EKyn offspring at ZT 6. Interestingly, extracellular hippocampal KYNA levels were only elevated in male EKyn offspring during the light phase. Decreases in extracellular glutamate levels were found in the dorsal hippocampus of EKyn male and female offspring, while decreased GABA levels were present only in males during the dark phase. The current findings suggest that the EKyn paradigm may be a useful tool for investigation of sex- and time-dependent changes in hippocampal neuromodulation elicited by prenatal KYNA elevation, which may influence behavioral phenotypes and have translational relevance to psychotic disorders.
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Affiliation(s)
- Courtney J Wright
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Katherine M Rentschler
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Nathan T J Wagner
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Ashley M Lewis
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Sarah Beggiato
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti, Italy
| | - Ana Pocivavsek
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
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Abad C, Karahoda R, Kastner P, Portillo R, Horackova H, Kucera R, Nachtigal P, Staud F. Profiling of Tryptophan Metabolic Pathways in the Rat Fetoplacental Unit During Gestation. Int J Mol Sci 2020; 21:ijms21207578. [PMID: 33066440 PMCID: PMC7589826 DOI: 10.3390/ijms21207578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/11/2020] [Accepted: 10/11/2020] [Indexed: 01/11/2023] Open
Abstract
Placental homeostasis of tryptophan is essential for fetal development and programming. The two main metabolic pathways (serotonin and kynurenine) produce bioactive metabolites with immunosuppressive, neurotoxic, or neuroprotective properties and their concentrations in the fetoplacental unit must be tightly regulated throughout gestation. Here, we investigated the expression/function of key enzymes/transporters involved in tryptophan pathways during mid-to-late gestation in rat placenta and fetal organs. Quantitative PCR and heatmap analysis revealed the differential expression of several genes involved in serotonin and kynurenine pathways. To identify the flux of substrates through these pathways, Droplet Digital PCR, western blot, and functional analyses were carried out for the rate-limiting enzymes and transporters. Our findings show that placental tryptophan metabolism to serotonin is crucial in mid-gestation, with a subsequent switch to fetal serotonin synthesis. Concurrently, at term, the close interplay between transporters and metabolizing enzymes of both placenta and fetal organs orchestrates serotonin homeostasis and prevents hyper/hypo-serotonemia. On the other hand, the placental production of kynurenine increases during pregnancy, with a low contribution of fetal organs throughout gestation. Any external insult to this tightly regulated harmony of transporters and enzymes within the fetoplacental unit may affect optimal in utero conditions and have a negative impact on fetal programming.
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Affiliation(s)
- Cilia Abad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (C.A.); (R.K.); (R.P.); (H.H.)
| | - Rona Karahoda
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (C.A.); (R.K.); (R.P.); (H.H.)
| | - Petr Kastner
- Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (P.K.); (R.K.)
| | - Ramon Portillo
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (C.A.); (R.K.); (R.P.); (H.H.)
| | - Hana Horackova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (C.A.); (R.K.); (R.P.); (H.H.)
| | - Radim Kucera
- Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (P.K.); (R.K.)
| | - Petr Nachtigal
- Department of Biological and Medical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic;
| | - Frantisek Staud
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic; (C.A.); (R.K.); (R.P.); (H.H.)
- Correspondence: ; Tel.: +420-495-067-407
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14
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Buck SA, Baratta AM, Pocivavsek A. Exposure to elevated embryonic kynurenine in rats: Sex-dependent learning and memory impairments in adult offspring. Neurobiol Learn Mem 2020; 174:107282. [PMID: 32738461 DOI: 10.1016/j.nlm.2020.107282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 12/14/2022]
Abstract
Distinct abnormalities in kynurenine pathway (KP) metabolism have been reported in various psychiatric disorders, including schizophrenia (SZ). Kynurenic acid (KYNA), a neuroactive metabolite of the KP, is elevated in individuals diagnosed with SZ and has been linked to cognitive impairments seen in the disorder. To further understand the role of KYNA in SZ etiology, we developed a prenatal insult model where kynurenine (100 mg/day) is fed to pregnant Wistar rats from embryonic day (ED) 15 to ED 22. As sex differences in the prevalence and severity of SZ have been observed, we presently investigated the impact of prenatal kynurenine exposure on KP metabolism and spatial learning and memory in male and female offspring. Specifically, brain tissue and plasma from offspring (control: ECon; kynurenine-treated: EKyn) in prepuberty (postnatal day (PD) 21), adolescence (PD 32-35), and adulthood (PD 56-85) were collected. Separate cohorts of adult offspring were tested in the Barnes maze to assess hippocampus- and prefrontal cortex-mediated learning and memory. Plasma tryptophan, kynurenine, and KYNA were unchanged between ECon and EKyn offspring across all three ages. Hippocampal and frontal cortex KYNA were elevated in male EKyn offspring only in adulthood, compared to ECon, while brain KYNA levels were unchanged in adult females. Male EKyn offspring were significantly impaired during acquisition of the Barnes maze and during reversal learning in the task. In female EKyn offspring, learning and memory remained relatively intact. Taken together, our data demonstrate that exposure to elevated kynurenine during the last week of gestation results in intriguing sex differences and further support the EKyn model as an attractive tool to study the pathophysiology of schizophrenia.
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Affiliation(s)
- Silas A Buck
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Annalisa M Baratta
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA.
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15
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Huang YS, Ogbechi J, Clanchy FI, Williams RO, Stone TW. IDO and Kynurenine Metabolites in Peripheral and CNS Disorders. Front Immunol 2020; 11:388. [PMID: 32194572 PMCID: PMC7066259 DOI: 10.3389/fimmu.2020.00388] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/18/2020] [Indexed: 12/12/2022] Open
Abstract
The importance of the kynurenine pathway in normal immune system function has led to an appreciation of its possible contribution to autoimmune disorders such as rheumatoid arthritis. Indoleamine-2,3-dioxygenase (IDO) activity exerts a protective function, limiting the severity of experimental arthritis, whereas deletion or inhibition exacerbates the symptoms. Other chronic disorder with an inflammatory component, such as atherosclerosis, are also suppressed by IDO activity. It is suggested that this overall anti-inflammatory activity is mediated by a change in the relative production or activity of Th17 and regulatory T cell populations. Kynurenines may play an anti-inflammatory role also in CNS disorders such as Huntington's disease, Alzheimer's disease and multiple sclerosis, in which signs of inflammation and neurodegeneration are involved. The possibility is discussed that in Huntington's disease kynurenines interact with other anti-inflammatory molecules such as Human Lymphocyte Antigen-G which may be relevant in other disorders. Kynurenine involvement may account for the protection afforded to animals with cerebral malaria and trypanosomiasis when they are treated with an inhibitor of kynurenine-3-monoxygenase (KMO). There is some evidence that changes in IL-10 may contribute to this protection and the relationship between kynurenines and IL-10 in arthritis and other inflammatory conditions should be explored. In addition, metabolites of kynurenine downstream of KMO, such as anthranilic acid and 3-hydroxy-anthranilic acid can influence inflammation, and the ratio of these compounds is a valuable biomarker of inflammatory status although the underlying molecular mechanisms of the changes require clarification. Hence it is essential that more effort be expended to identify their sites of action as potential targets for drug development. Finally, we discuss increasing awareness of the epigenetic regulation of IDO, for example by DNA methylation, a phenomenon which may explain differences between individuals in their susceptibility to arthritis and other inflammatory disorders.
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Affiliation(s)
- Yi-Shu Huang
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Joy Ogbechi
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Felix I Clanchy
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Richard O Williams
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | - Trevor W Stone
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
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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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17
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Ogbechi J, Clanchy FI, Huang YS, Topping LM, Stone TW, Williams RO. IDO activation, inflammation and musculoskeletal disease. Exp Gerontol 2019; 131:110820. [PMID: 31884118 DOI: 10.1016/j.exger.2019.110820] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 12/11/2022]
Abstract
The IDO/kynurenine pathway is now established as a major regulator of immune system function. The initial enzyme, indoleamine 2,3-dioxygenase (IDO1) is induced by IFNγ, while tryptophan-2,3-dioxygenase (TDO) is induced by corticosteroids. The pathway is therefore positioned to mediate the effects of systemic inflammation or stress-induced steroids on tissue function and its expression increases with age. Disorders of the musculoskeletal system are a common feature of ageing and many of these conditions are characterized by an inflammatory state. In inflammatory arthritis and related disorders, kynurenine protects against the development of disease, while inhibition or deletion of IDO1 increases its severity. The long-term regulation of autoimmune disorders may be influenced by the epigenetic modulation of kynurenine pathway genes, with recent data suggesting that methylation of IDO may be involved. Osteoporosis is also associated with abnormalities of the kynurenine pathway, reflected in an inversion of the ratio between blood levels of the metabolites anthranilic acid and 3-hydroxy-anthranilic acid. This review discusses evidence to date on the role of the IDO/kynurenine pathway and the highly prevalent age-related disorders of osteoporosis and rheumatoid arthritis and identifies key areas that require further research.
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Affiliation(s)
- Joy Ogbechi
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK
| | - Felix I Clanchy
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK
| | - Yi-Shu Huang
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK
| | - Louise M Topping
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK
| | - Trevor W Stone
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK
| | - Richard O Williams
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford OX3 7FY, UK.
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18
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Baratta AM, Kanyuch NR, Cole CA, Valafar H, Deslauriers J, Pocivavsek A. Acute sleep deprivation during pregnancy in rats: Rapid elevation of placental and fetal inflammation and kynurenic acid. Neurobiol Stress 2019; 12:100204. [PMID: 32258253 PMCID: PMC7109515 DOI: 10.1016/j.ynstr.2019.100204] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 11/27/2019] [Accepted: 12/11/2019] [Indexed: 01/19/2023] Open
Abstract
The kynurenine pathway (KP) is the dominant pathway for tryptophan degradation in the mammalian body and emerging evidence suggests that acute episodes of sleep deprivation (SD) disrupt tryptophan metabolism via the KP. Increases in the neuroactive KP metabolite kynurenic acid (KYNA) during pregnancy may lead to a higher risk for disrupted neurodevelopment in the offspring. As pregnancy is a critical period during which several factors, including sleep disruptions, could disrupt the fetal environment, we presently explored the relationship between maternal SD and KP metabolism and immune pathways in maternal, placenta, and fetal tissues. Pregnant Wistar rat dams were sleep deprived by gentle handling for 5 h from zeitgeber time (ZT) 0 to ZT 5. Experimental cohorts included: i) controls, ii) one session of SD on embryonic day (ED) 18 or iii) three sessions of SD occurring daily on ED 16, ED 17 and ED 18. Maternal (plasma, brain), placental and fetal (plasma, brain) tissues were collected immediately after the last session of SD or after 24 h of recovery from SD. Respective controls were euthanized at ZT 5 on ED 18 or ED 19. Maternal plasma corticosterone and fetal brain KYNA were significantly elevated only after one session of SD on ED 18. Importantly, maternal plasma corticosterone levels correlated significantly with fetal brain KYNA levels. In addition, placental levels of the proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6) were increased following maternal SD, suggesting a relationship between placental immune response to SD and fetal brain KYNA accumulation. Collectively, our results demonstrate that sleep loss during the last week of gestation can adversely impact maternal stress, placental immune function, and fetal brain KYNA levels. We introduce KYNA as a novel molecular target influenced by sleep loss during pregnancy. Prenatal sleep deprivation influences kynurenine pathway metabolism in utero. Fetal brain kynurenic acid (KYNA) is elevated after maternal sleep deprivation. Maternal plasma corticosterone is increased after sleep deprivation. Prenatal sleep deprivation induces placental and fetal brain cytokines. These data support an interplay with stress, in utero inflammation, and KYNA.
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Affiliation(s)
- Annalisa M Baratta
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nickole R Kanyuch
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Casey A Cole
- College of Engineering and Computing, University of South Carolina, Columba, South Carolina, USA
| | - Homayoun Valafar
- College of Engineering and Computing, University of South Carolina, Columba, South Carolina, USA
| | - Jessica Deslauriers
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.,Center of Excellence for Stress and Mental Health, Veterans Affairs Hospital, La Jolla, CA, USA
| | - Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
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19
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Notarangelo FM, Beggiato S, Schwarcz R. Assessment of Prenatal Kynurenine Metabolism Using Tissue Slices: Focus on the Neosynthesis of Kynurenic Acid in Mice. Dev Neurosci 2019; 41:102-111. [PMID: 31117076 DOI: 10.1159/000499736] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 03/19/2019] [Indexed: 01/17/2023] Open
Abstract
Several lines of evidence support the hypothesis that abnormally elevated brain levels of kynurenic acid (KYNA), a metabolite of the kynurenine pathway (KP) of tryptophan degradation, play a pathophysiologically significant role in schizophrenia and other major neurodevelopmental disorders. Studies in experimental animal models suggest that KP impairments in these diseases may originate already in utero since prenatal administration of KYNA's bioprecursor, kynurenine, leads to biochemical and structural abnormalities as well as distinct cognitive impairments in adulthood. As KP metabolism during pregnancy is still insufficiently understood, we designed this study to examine the de novo synthesis of KYNA and 3-hydroxykynurenine (3-HK), an alternative biologically active product of kynurenine degradation, in tissue slices obtained from pregnant mice on gestational day (GD) 18. Fetal brain and liver, placenta, and maternal brain and liver were collected, and the tissues were incubated in vitroin the absence or presence of micromolar concentrations of kynurenine. KYNA and 3-HK were measured in the extracellular milieu. Basal and newly produced KYNA was detected in all cases. As KYNA formation exceeded 3-HK production by 2-3 orders of magnitude in the placenta and maternal brain, and as very little 3-HK neosynthesis was detectable in fetal brain tissue, detailed follow-up experiments focused on KYNA only. The fetal brain produced 3-4 times more KYNA than the maternal brain and placenta, though less than the maternal and fetal liver. No significant differences were observed when using tissues obtained on GD 14 and GD 18. Pharmacological inhibition of KYNA's main biosynthetic enzymes, kynurenine aminotransferase (KAT) I and KAT II, revealed qualitative and quantitative differences between the tissues, with a preferential role of KAT I in the fetal and maternal brain and of KAT II in the fetal and maternal liver. Findings using tissue slices from KAT II knockout mice confirmed these conclusions. Together, these results clarify the dynamics of KP metabolism during pregnancy and provide the basis for the conceptualization of interventions aimed at manipulating cerebral KP function in the prenatal period.
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Affiliation(s)
- Francesca M Notarangelo
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA,
| | - Sarah Beggiato
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
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20
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The ‘Yin’ and the ‘Yang’ of the kynurenine pathway: excitotoxicity and neuroprotection imbalance in stress-induced disorders. Behav Pharmacol 2019; 30:163-186. [DOI: 10.1097/fbp.0000000000000477] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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21
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Pocivavsek A, Elmer GI, Schwarcz R. Inhibition of kynurenine aminotransferase II attenuates hippocampus-dependent memory deficit in adult rats treated prenatally with kynurenine. Hippocampus 2018; 29:73-77. [PMID: 30311334 DOI: 10.1002/hipo.23040] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/01/2018] [Accepted: 10/07/2018] [Indexed: 11/11/2022]
Abstract
A combination of genetic and environmental factors contributes to schizophrenia (SZ), a catastrophic psychiatric disorder with a hypothesized neurodevelopmental origin. Increases in the brain levels of the tryptophan metabolite kynurenic acid (KYNA), an endogenous antagonist of α7 nicotinic acetylcholine and NMDA receptors, have been implicated specifically in the cognitive deficits seen in persons with SZ. Here we evaluated this role of KYNA by adding the KYNA precursor kynurenine (100 mg/day) to chow fed to pregnant rat dams from embryonic day (ED) 15 to ED 22 (control: ECon; kynurenine treated: EKyn). Upon termination of the treatment, all rats received normal rodent chow until the animals were evaluated in adulthood (postnatal days 56-85). EKyn treatment resulted in increased extracellular KYNA and reduced extracellular glutamate in the hippocampus, measured by in vivo microdialysis, and caused impairments in hippocampus-dependent learning in adult rats. Acute administration of BFF816, a systemically active inhibitor of kynurenine aminotransferase II (KAT II), the major KYNA-synthesizing enzyme in the brain, normalized neurochemistry and prevented contextual memory deficits in adult EKyn animals. Collectively, these results demonstrate that acute inhibition of KYNA neosynthesis can overcome cognitive impairments that arise as a consequence of elevated brain KYNA in early brain development.
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Affiliation(s)
- Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Greg I Elmer
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
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22
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Beggiato S, Notarangelo FM, Sathyasaikumar KV, Giorgini F, Schwarcz R. Maternal genotype determines kynurenic acid levels in the fetal brain: Implications for the pathophysiology of schizophrenia. J Psychopharmacol 2018; 32:1223-1232. [PMID: 30354938 DOI: 10.1177/0269881118805492] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Several studies suggest a pathophysiologically relevant association between increased brain levels of the neuroinhibitory tryptophan metabolite kynurenic acid and cognitive dysfunctions in people with schizophrenia. Elevated kynurenic acid in schizophrenia may be secondary to a genetic alteration of kynurenine 3-monooxygenase, a pivotal enzyme in the kynurenine pathway of tryptophan degradation. In rats, prenatal exposure to kynurenine, the direct bioprecursor of kynurenic acid, induces cognitive impairments reminiscent of schizophrenia in adulthood, suggesting a developmental dimension to the link between kynurenic acid and schizophrenia. AIM The purpose of this study was to explore the possible impact of the maternal genotype on kynurenine pathway metabolism. METHODS We exposed pregnant wild-type ( Kmo+/+ ) and heterozygous ( Kmo+/-) mice to kynurenine (10 mg/day) during the last week of gestation and determined the levels of kynurenic acid and two other neuroactive kynurenine pathway metabolites, 3-hydroxykynurenine and quinolinic acid, in fetal brain and placenta on embryonic day 17/18. RESULTS Maternal kynurenine treatment raised kynurenic acid levels significantly more in the brain of heterozygous offspring of Kmo+/- than in the brain of Kmo+/+ offspring. Conversely, 3-hydroxykynurenine and quinolinic acid levels in the fetal brain tended to be lower in heterozygous animals derived from kynurenine-treated Kmo+/- mice than in corresponding Kmo+/+ offspring. Genotype-related effects on the placenta were qualitatively similar but less pronounced. Kynurenine treatment also caused a preferential elevation in cerebral kynurenic acid levels in Kmo+/- compared to Kmo+/+ dams. CONCLUSIONS The disproportionate kynurenic acid increase in the brain of Kmo+/- animals indicates that the maternal Kmo genotype may play a key role in the pathophysiology of schizophrenia.
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Affiliation(s)
- Sarah Beggiato
- 1 Department of Life Sciences and Biotechnologies, University of Ferrara, Ferrara, Italy.,2 Laboratory for the Technology of Advanced Therapies (LTTA Centre), University of Ferrara, Ferrara, Italy
| | - Francesca M Notarangelo
- 3 Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Flaviano Giorgini
- 4 Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Robert Schwarcz
- 3 Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
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Early Maternal Deprivation Induces Microglial Activation, Alters Glial Fibrillary Acidic Protein Immunoreactivity and Indoleamine 2,3-Dioxygenase during the Development of Offspring Rats. Mol Neurobiol 2018; 56:1096-1108. [PMID: 29873040 DOI: 10.1007/s12035-018-1161-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 05/29/2018] [Indexed: 02/07/2023]
Abstract
Maternal deprivation (MD) induces behavioral changes and impacts brain circuits that could be associated with the pathophysiology of depression. This study investigated the markers of microglia and astrocyte activation as well as indoleamine 2,3-dioxygenase (IDO) expression in developmental programming after early life MD (on postnatal days (PNDs) 20, 30, 40, and 60). On PND 60, the rats that were subjected to MD displayed depressive-like behavior. On PND 10, it was found that there was a decrease in the level of glial fibrillary acidic protein (GFAP) immunopositive cells, a decrease in the level of IDO expression, and an increase in the level of Iba-1 (microglial marker) in the hippocampus of rats that were subjected to MD. On PND 20, levels of GFAP were also found to have decreased in the hippocampus, and there was an increase in the level of Iba-1 in the hippocampus. AIF-1 (microglial marker) expression was observed in the PFC following MD. On PND 30, the levels of Iba-1 remained elevated. On PND 40, the levels of GFAP were found to have increased in the hippocampus of rats that were subjected to MD. On PND 60, the levels of GFAP and AIF-1 remained elevated following MD. These results suggest that early life stress induces negative developmental programming in rats, as demonstrated by depressive-like behavior in adult life. Moreover, MD increases microglial activation in both early and late developmental phases. The levels of GFAP and IDO decreased in the early stages but were found to be higher in later developmental periods. These findings suggest that MD could differentially affect the expression of the IDO enzyme, astrocytes, and microglial activation depending on the neurodevelopmental period. The onset of an inflammatory state from resident brain cells could be associated with the activation of the kynurenine pathway and the development of depressive behavior in adulthood.
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Stone TW, McPherson M, Gail Darlington L. Obesity and Cancer: Existing and New Hypotheses for a Causal Connection. EBioMedicine 2018; 30:14-28. [PMID: 29526577 PMCID: PMC5952217 DOI: 10.1016/j.ebiom.2018.02.022] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 02/07/2023] Open
Abstract
Existing explanations of obesity-associated cancer emphasise direct mutagenic effects of dietary components or hormonal imbalance. Some of these hypotheses are reviewed briefly, but recent evidence suggests a major role for chronic inflammation in cancer risk, possibly involving dietary content. These ideas include the inflammation-induced activation of the kynurenine pathway and its role in feeding and metabolism by activation of the aryl hydrocarbon receptor (AHR) and by modulating synaptic transmission in the brain. Evidence for a role of the kynurenine pathway in carcinogenesis then provides a potentially major link between obesity and cancer. A second new hypothesis is based on evidence that serine proteases can deplete cells of the tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin. These enzymes include mammalian chymotryptic proteases released by pro-inflammatory neutrophils and macrophages. Blood levels of chymotrypsin itself increase in parallel with food intake. The mechanistically similar bacterial enzyme subtilisin is widespread in the environment, animal probiotics, meat processing and cleaning products. Simple public health schemes in these areas, with selective serine protease inhibitors and AHR antagonists and could prevent a range of intestinal and other cancers.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Megan McPherson
- School of Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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25
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The role of N-methyl-d-aspartate receptors and metabotropic glutamate receptor 5 in the prepulse inhibition paradigms for studying schizophrenia: pharmacology, neurodevelopment, and genetics. Behav Pharmacol 2018; 29:13-27. [DOI: 10.1097/fbp.0000000000000352] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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26
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Goeden N, Notarangelo FM, Pocivavsek A, Beggiato S, Bonnin A, Schwarcz R. Prenatal Dynamics of Kynurenine Pathway Metabolism in Mice: Focus on Kynurenic Acid. Dev Neurosci 2017; 39:519-528. [PMID: 29080891 DOI: 10.1159/000481168] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/31/2017] [Indexed: 01/09/2023] Open
Abstract
The kynurenine pathway (KP), the major catabolic route of tryptophan in mammals, contains several neuroactive metabolites, including kynurenic acid (KYNA) and 3-hydroxykynurenine (3-HK). KP metabolism, and especially the fate of KYNA, during pregnancy is poorly understood, yet it may play a significant role in the development of psychiatric disorders later in life. The present study was designed to investigate the prenatal features of KP metabolism in vivo, with special focus on KYNA. To this end, pregnant CD-1 mice were treated systemically with kynurenine (100 mg/kg), KYNA (10 mg/kg), or saline on embryonic day 18. As expected, administration of either kynurenine or KYNA increased KYNA levels in the maternal plasma and placenta. Maternal kynurenine treatment also raised kynurenine levels in the fetal plasma and brain, demonstrating the ability of this pivotal KP metabolite to cross the placenta and increase the levels of both KYNA and 3-HK in the fetal brain. In contrast, maternal administration of KYNA caused only a small, nonsignificant elevation in KYNA levels in fetal plasma and brain. Complementary experiments using an ex vivo placental perfusion procedure confirmed the significant transplacental transfer of kynurenine and demonstrated that only a very small fraction of maternal kynurenine is converted to KYNA in the placenta and released into the fetal compartment under physiological conditions. Jointly, these results help to clarify the contributions of the maternal circulation and the placenta to fetal KYNA in the late prenatal period.
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Affiliation(s)
- Nick Goeden
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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27
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Kelly JR, Minuto C, Cryan JF, Clarke G, Dinan TG. Cross Talk: The Microbiota and Neurodevelopmental Disorders. Front Neurosci 2017; 11:490. [PMID: 28966571 PMCID: PMC5605633 DOI: 10.3389/fnins.2017.00490] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/17/2017] [Indexed: 12/11/2022] Open
Abstract
Humans evolved within a microbial ecosystem resulting in an interlinked physiology. The gut microbiota can signal to the brain via the immune system, the vagus nerve or other host-microbe interactions facilitated by gut hormones, regulation of tryptophan metabolism and microbial metabolites such as short chain fatty acids (SCFA), to influence brain development, function and behavior. Emerging evidence suggests that the gut microbiota may play a role in shaping cognitive networks encompassing emotional and social domains in neurodevelopmental disorders. Drawing upon pre-clinical and clinical evidence, we review the potential role of the gut microbiota in the origins and development of social and emotional domains related to Autism spectrum disorders (ASD) and schizophrenia. Small preliminary clinical studies have demonstrated gut microbiota alterations in both ASD and schizophrenia compared to healthy controls. However, we await the further development of mechanistic insights, together with large scale longitudinal clinical trials, that encompass a systems level dimensional approach, to investigate whether promising pre-clinical and initial clinical findings lead to clinical relevance.
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Affiliation(s)
- John R Kelly
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - Chiara Minuto
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - John F Cryan
- APC Microbiome Institute, University College CorkCork, Ireland.,Department of Anatomy and Neuroscience, University College CorkCork, Ireland
| | - Gerard Clarke
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - Timothy G Dinan
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
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Preferential Disruption of Prefrontal GABAergic Function by Nanomolar Concentrations of the α7nACh Negative Modulator Kynurenic Acid. J Neurosci 2017; 37:7921-7929. [PMID: 28729445 DOI: 10.1523/jneurosci.0932-17.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/20/2017] [Accepted: 07/11/2017] [Indexed: 12/27/2022] Open
Abstract
Increased concentrations of kynurenic acid (KYNA) in the prefrontal cortex (PFC) are thought to contribute to the development of cognitive deficits observed in schizophrenia. Although this view is consistent with preclinical studies showing a negative impact of prefrontal KYNA elevation on executive function, the mechanism underlying such a disruption remains unclear. Here, we measured changes in local field potential (LFP) responses to ventral hippocampal stimulation in vivo and conducted whole-cell patch-clamp recordings in brain slices to reveal how nanomolar concentrations of KYNA alter synaptic transmission in the PFC of male adult rats. Our data show that prefrontal infusions of KYNA attenuated the inhibitory component of PFC LFP responses, a disruption that resulted from local blockade of α7-nicotinic acetylcholine receptors (α7nAChR). At the cellular level, we found that the inhibitory action exerted by KYNA in the PFC occurred primarily at local GABAergic synapses through an α7nAChR-dependent presynaptic mechanism. As a result, the excitatory-inhibitory ratio of synaptic transmission becomes imbalanced in a manner that correlates highly with the level of GABAergic suppression by KYNA. Finally, prefrontal infusion of a GABAAR positive allosteric modulator was sufficient to overcome the disrupting effect of KYNA and normalized the pattern of LFP inhibition in the PFC. Thus, the preferential inhibitory effect of KYNA on prefrontal GABAergic transmission could contribute to the onset of cognitive deficits observed in schizophrenia because proper GABAergic control of PFC output is one key mechanism for supporting such cortical functions.SIGNIFICANCE STATEMENT Brain kynurenic acid (KYNA) is an astrocyte-derived metabolite and its abnormal elevation in the prefrontal cortex (PFC) is thought to impair cognitive functions in individuals with schizophrenia. However, the mechanism underlying the disrupting effect of KYNA remains unclear. Here we found that KYNA biases the excitatory-inhibitory balance of prefrontal synaptic activity toward a state of disinhibition. Such disruption emerges as a result of a preferential suppression of local GABAergic transmission by KYNA via presynaptic inhibition of α7-nicotinic acetylcholine receptor signaling. Therefore, the degree of GABAergic dysregulation in the PFC could be a clinically relevant contributing factor for the onset of cognitive deficits resulting from abnormal increases of cortical KYNA.
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Notarangelo FM, Schwarcz R. Restraint Stress during Pregnancy Rapidly Raises Kynurenic Acid Levels in Mouse Placenta and Fetal Brain. Dev Neurosci 2017; 38:458-468. [PMID: 28214871 DOI: 10.1159/000455228] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/19/2016] [Indexed: 12/13/2022] Open
Abstract
Stressful events during pregnancy adversely affect brain development and may increase the risk of psychiatric disorders later in life. Early changes in the kynurenine (KYN) pathway (KP) of tryptophan (TRP) degradation, which contains several neuroactive metabolites, including kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK), and quinolinic acid (QUIN), may constitute a molecular link between prenatal stress and delayed pathological consequences. To begin testing this hypothesis experimentally, we examined the effects of a 2-h restraint stress on KP metabolism in pregnant FVB/N mice on gestational day 17. TRP, KYN, KYNA, 3-HK, and QUIN levels were measured in maternal and fetal plasma and brain, as well as in the placenta, immediately after stress termination and 2 h later. In the same animals, we determined the activity of TRP 2,3-dioxygenase (TDO) in the maternal liver and in the placenta. Compared to unstressed controls, mostly transient changes in KP metabolism were observed in all of the tissues examined. Specifically, stress caused significant elevations of KYNA levels in the maternal plasma, placenta, and fetal brain, and also resulted in increased levels of TRP and KYN in the placenta, fetal plasma, and fetal brain. In contrast, 3-HK and QUIN levels remained unchanged from control values in all tissues at any time point. In the maternal liver, TDO activity was increased 2 h after stress cessation. Taken together, these findings indicate that an acute stress during the late gestational period preferentially affects the KYNA branch of KP metabolism in the fetal brain. Possible long-term consequences for postnatal brain development and pathology remain to be examined.
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Affiliation(s)
- Francesca M Notarangelo
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
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Hernandez-Martinez JM, Forrest CM, Darlington LG, Smith RA, Stone TW. Quinolinic acid induces neuritogenesis in SH-SY5Y neuroblastoma cells independently of NMDA receptor activation. Eur J Neurosci 2017; 45:700-711. [PMID: 27973747 DOI: 10.1111/ejn.13499] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 12/25/2022]
Abstract
Glutamate and nicotinamide adenine dinucleotide (NAD+ ) have been implicated in neuronal development and several types of cancer. The kynurenine pathway of tryptophan metabolism includes quinolinic acid (QA) which is both a selective agonist at N-methyl-D-aspartate (NMDA) receptors and also a precursor for the formation of NAD+ . The effect of QA on cell survival and differentiation has therefore been examined on SH-SY5Y human neuroblastoma cells. Retinoic acid (RA, 10 μm) induced differentiation of SH-SY5Y cells into a neuronal phenotype showing neurite growth. QA (50-150 nm) also caused a concentration-dependent increase in the neurite/soma ratio, indicating differentiation. Both RA and QA increased expression of the neuronal marker β3-tubulin in whole-cell homogenates and in the neuritic fraction assessed using a neurite outgrowth assay. Expression of the neuronal proliferation marker doublecortin revealed that, unlike RA, QA did not decrease the number of mitotic cells. QA-induced neuritogenesis coincided with an increase in the generation of reactive oxygen species. Neuritogenesis was prevented by diphenylene-iodonium (an inhibitor of NADPH oxidase) and superoxide dismutase, supporting the involvement of reactive oxygen species. NMDA itself did not promote neuritogenesis and the NMDA antagonist dizocilpine (MK-801) did not prevent quinolinate-induced neuritogenesis, indicating that the effects of QA were independent of NMDA receptors. Nicotinamide caused a significant increase in the neurite/soma ratio and the expression of β3-tubulin in the neuritic fraction. Taken together, these results suggest that QA induces neuritogenesis by promoting oxidizing conditions and affecting the availability of NAD+ , independently of NMDA receptors.
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Affiliation(s)
- Juan-Manuel Hernandez-Martinez
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK
| | - Caroline M Forrest
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK
| | | | - Robert A Smith
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK
| | - Trevor W Stone
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK
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31
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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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32
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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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Notarangelo FM, Pocivavsek A. Elevated kynurenine pathway metabolism during neurodevelopment: Implications for brain and behavior. Neuropharmacology 2017; 112:275-285. [PMID: 26944732 PMCID: PMC5010529 DOI: 10.1016/j.neuropharm.2016.03.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 02/26/2016] [Accepted: 03/01/2016] [Indexed: 11/20/2022]
Abstract
The kynurenine pathway (KP) of tryptophan degradation contains several neuroactive metabolites that may influence brain function in health and disease. Mounting focus has been dedicated to investigating the role of these metabolites during neurodevelopment and elucidating their involvement in the pathophysiology of psychiatric disorders with a developmental component, such as schizophrenia. In this review, we describe the changes in KP metabolism in the brain from gestation until adulthood and illustrate how environmental and genetic factors affect the KP during development. With a particular focus on kynurenic acid, the antagonist of α7 nicotinic acetylcholine (α7nACh) and N-methyl-d-aspartate (NMDA) receptors, both implicated in modulating brain development, we review animal models designed to ascertain the role of perinatal KP elevation on long-lasting biochemical, neuropathological, and behavioral deficits later in life. We present new data demonstrating that combining perinatal choline-supplementation, to potentially increase activation of α7nACh receptors during development, with embryonic kynurenine manipulation is effective in attenuating cognitive impairments in adult rat offspring. With these findings in mind, we conclude the review by discussing the advancement of therapeutic interventions that would target not only symptoms, but potentially the root cause of central nervous system diseases that manifest from a perinatal KP insult. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'.
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Affiliation(s)
- Francesca M Notarangelo
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
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Quinolinic acid neurotoxicity: Differential roles of astrocytes and microglia via FGF-2-mediated signaling in redox-linked cytoskeletal changes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:3001-3014. [PMID: 27663072 DOI: 10.1016/j.bbamcr.2016.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/12/2016] [Accepted: 09/17/2016] [Indexed: 11/24/2022]
Abstract
QUIN is a glutamate agonist playing a role in the misregulation of the cytoskeleton, which is associated with neurodegeneration in rats. In this study, we focused on microglial activation, FGF2/Erk signaling, gap junctions (GJs), inflammatory parameters and redox imbalance acting on cytoskeletal dynamics of the in QUIN-treated neural cells of rat striatum. FGF-2/Erk signaling was not altered in QUIN-treated primary astrocytes or neurons, however cytoskeleton was disrupted. In co-cultured astrocytes and neurons, QUIN-activated FGF2/Erk signaling prevented the cytoskeleton from remodeling. In mixed cultures (astrocyte, neuron, microglia), QUIN-induced FGF-2 increased level failed to activate Erk and promoted cytoskeletal destabilization. The effects of QUIN in mixed cultures involved redox imbalance upstream of Erk activation. Decreased connexin 43 (Cx43) immunocontent and functional GJs, was also coincident with disruption of the cytoskeleton in primary astrocytes and mixed cultures. We postulate that in interacting astrocytes and neurons the cytoskeleton is preserved against the insult of QUIN by activation of FGF-2/Erk signaling and proper cell-cell interaction through GJs. In mixed cultures, the FGF-2/Erk signaling is blocked by the redox imbalance associated with microglial activation and disturbed cell communication, disrupting the cytoskeleton. Thus, QUIN signal activates differential mechanisms that could stabilize or destabilize the cytoskeleton of striatal astrocytes and neurons in culture, and glial cells play a pivotal role in these responses preserving or disrupting a combination of signaling pathways and cell-cell interactions. Taken together, our findings shed light into the complex role of the active interaction of astrocytes, neurons and microglia in the neurotoxicity of QUIN.
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Forrest CM, Kennedy PGE, Rodgers J, Dalton RN, Turner C, Darlington LG, Cobb SR, Stone TW. Kynurenine pathway metabolism following prenatal KMO inhibition and in Mecp2 +/- mice, using liquid chromatography-tandem mass spectrometry. Neurochem Int 2016; 100:110-119. [PMID: 27623092 PMCID: PMC5115650 DOI: 10.1016/j.neuint.2016.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/22/2016] [Accepted: 09/09/2016] [Indexed: 12/17/2022]
Abstract
To quantify the full range of tryptophan metabolites along the kynurenine pathway, a liquid chromatography – tandem mass spectrometry method was developed and used to analyse brain extracts of rodents treated with the kynurenine-3-mono-oxygenase (KMO) inhibitor Ro61-8048 during pregnancy. There were significant increases in the levels of kynurenine, kynurenic acid, anthranilic acid and 3-hydroxy-kynurenine (3-HK) in the maternal brain after 5 h but not 24 h, while the embryos exhibited high levels of kynurenine, kynurenic acid and anthranilic acid after 5 h which were maintained at 24 h post-treatment. At 24 h there was also a strong trend to an increase in quinolinic acid levels (P = 0.055). No significant changes were observed in any of the other kynurenine metabolites. The results confirm the marked increase in the accumulation of some neuroactive kynurenines when KMO is inhibited, and re-emphasise the potential importance of changes in anthranilic acid. The prolonged duration of metabolite accumulation in the embryo brains indicates a trapping of compounds within the embryonic CNS independently of maternal levels. When brains were examined from young mice heterozygous for the meCP2 gene – a potential model for Rett syndrome - no differences were noted from control mice, suggesting that the proposed roles for kynurenines in autism spectrum disorder are not relevant to Rett syndrome, supporting its recognition as a distinct, independent, condition. Pregnant rats were treated with an inhibitor of kynurenine-3-monoxygenase. Levels of several kynurenine metabolites increased in the maternal and foetal brains. The maternal changes at 5 h disappeared by 24 h, but were maintained in embryos. No changes were noted in the brains of Mecp2+/− mice. KMO inhibition but not Mecp2+/− suppression alters kynurenine metabolism.
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Affiliation(s)
- Caroline M Forrest
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Peter G E Kennedy
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Jean Rodgers
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - R Neil Dalton
- WellChild Laboratory, Evelina London Children's Hospital, King's College London, Lambeth Palace Road, London, SE1 7EH, UK
| | - Charles Turner
- WellChild Laboratory, Evelina London Children's Hospital, King's College London, Lambeth Palace Road, London, SE1 7EH, UK
| | - L Gail Darlington
- Department of Internal Medicine, Ashtead Hospital, Ashtead, Surrey, KT21 2SB, UK
| | - Stuart R Cobb
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Trevor W Stone
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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The Gut-Brain Axis, BDNF, NMDA and CNS Disorders. Neurochem Res 2016; 41:2819-2835. [PMID: 27553784 DOI: 10.1007/s11064-016-2039-1] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/09/2016] [Accepted: 08/17/2016] [Indexed: 02/08/2023]
Abstract
Gastro-intestinal (GI) microbiota and the 'gut-brain axis' are proving to be increasingly relevant to early brain development and the emergence of psychiatric disorders. This review focuses on the influence of the GI tract on Brain-Derived Neurotrophic Factor (BDNF) and its relationship with receptors for N-methyl-D-aspartate (NMDAR), as these are believed to be involved in synaptic plasticity and cognitive function. NMDAR may be associated with the development of schizophrenia and a range of other psychopathologies including neurodegenerative disorders, depression and dementias. An analysis of the routes and mechanisms by which the GI microbiota contribute to the pathophysiology of BDNF-induced NMDAR dysfunction could yield new insights relevant to developing novel therapeutics for schizophrenia and related disorders. In the absence of GI microbes, central BDNF levels are reduced and this inhibits the maintenance of NMDAR production. A reduction of NMDAR input onto GABA inhibitory interneurons causes disinhibition of glutamatergic output which disrupts the central signal-to-noise ratio and leads to aberrant synaptic behaviour and cognitive deficits. Gut microbiota can modulate BDNF function in the CNS, via changes in neurotransmitter function by affecting modulatory mechanisms such as the kynurenine pathway, or by changes in the availability and actions of short chain fatty acids (SCFAs) in the brain. Interrupting these cycles by inducing changes in the gut microbiota using probiotics, prebiotics or antimicrobial drugs has been found promising as a preventative or therapeutic measure to counteract behavioural deficits and these may be useful to supplement the actions of drugs in the treatment of CNS disorders.
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Giovanoli S, Weber-Stadlbauer U, Schedlowski M, Meyer U, Engler H. Prenatal immune activation causes hippocampal synaptic deficits in the absence of overt microglia anomalies. Brain Behav Immun 2016; 55:25-38. [PMID: 26408796 DOI: 10.1016/j.bbi.2015.09.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 12/11/2022] Open
Abstract
Prenatal exposure to infectious or inflammatory insults can increase the risk of developing neuropsychiatric disorder in later life, including schizophrenia, bipolar disorder, and autism. These brain disorders are also characterized by pre- and postsynaptic deficits. Using a well-established mouse model of maternal exposure to the viral mimetic polyriboinosinic-polyribocytidilic acid [poly(I:C)], we examined whether prenatal immune activation might cause synaptic deficits in the hippocampal formation of pubescent and adult offspring. Based on the widely appreciated role of microglia in synaptic pruning, we further explored possible associations between synaptic deficits and microglia anomalies in offspring of poly(I:C)-exposed and control mothers. We found that prenatal immune activation induced an adult onset of presynaptic hippocampal deficits (as evaluated by synaptophysin and bassoon density). The early-life insult further caused postsynaptic hippocampal deficits in pubescence (as evaluated by PSD95 and SynGAP density), some of which persisted into adulthood. In contrast, prenatal immune activation did not change microglia (or astrocyte) density, nor did it alter their activation phenotypes. The prenatal manipulation did also not cause signs of persistent systemic inflammation. Despite the absence of overt glial anomalies or systemic inflammation, adult offspring exposed to prenatal immune activation displayed increased hippocampal IL-1β levels. Taken together, our findings demonstrate that age-dependent synaptic deficits and abnormal pro-inflammatory cytokine expression can occur during postnatal brain maturation in the absence of microglial anomalies or systemic inflammation.
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Affiliation(s)
- Sandra Giovanoli
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - Ulrike Weber-Stadlbauer
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland; Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland
| | - Manfred Schedlowski
- Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Urs Meyer
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland; Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland.
| | - Harald Engler
- Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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Modabbernia A, Velthorst E, Gennings C, De Haan L, Austin C, Sutterland A, Mollon J, Frangou S, Wright R, Arora M, Reichenberg A. Early-life metal exposure and schizophrenia: A proof-of-concept study using novel tooth-matrix biomarkers. Eur Psychiatry 2016; 36:1-6. [PMID: 27311101 DOI: 10.1016/j.eurpsy.2016.03.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/15/2016] [Accepted: 03/21/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Despite evidence for the effects of metals on neurodevelopment, the long-term effects on mental health remain unclear due to methodological limitations. Our objective was to determine the feasibility of studying metal exposure during critical neurodevelopmental periods and to explore the association between early-life metal exposure and adult schizophrenia. METHODS We analyzed childhood-shed teeth from nine individuals with schizophrenia and five healthy controls. We investigated the association between exposure to lead (Pb(2+)), manganese (Mn(2+)), cadmium (Cd(2+)), copper (Cu(2+)), magnesium (Mg(2+)), and zinc (Zn(2+)), and schizophrenia, psychotic experiences, and intelligence quotient (IQ). We reconstructed the dose and timing of early-life metal exposures using laser ablation inductively coupled plasma mass spectrometry. RESULTS We found higher early-life Pb(2+) exposure among patients with schizophrenia than controls. The differences in log Mn(2+) and log Cu(2+) changed relatively linearly over time to postnatal negative values. There was a positive correlation between early-life Pb(2+) levels and psychotic experiences in adulthood. Moreover, we found a negative correlation between Pb(2+) levels and adult IQ. CONCLUSIONS In our proof-of-concept study, using tooth-matrix biomarker that provides direct measurement of exposure in the fetus and newborn, we provide support for the role of metal exposure during critical neurodevelopmental periods in psychosis.
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Affiliation(s)
- A Modabbernia
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, United States; Seaver Center for Autism Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, United States; Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States.
| | - E Velthorst
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, United States; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - C Gennings
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - L De Haan
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - C Austin
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - A Sutterland
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - J Mollon
- Department of Psychosis Studies, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, England, United Kingdom
| | - S Frangou
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, United States; Psychosis Research Program, Icahn School of Medicine at Mount Sinai, New York, United States
| | - R Wright
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - M Arora
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - A Reichenberg
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, United States; Seaver Center for Autism Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, United States; Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, United States; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, United States
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Astrocytes as Pharmacological Targets in the Treatment of Schizophrenia. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2016. [DOI: 10.1016/b978-0-12-800981-9.00025-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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O'Farrell K, Harkin A. Stress-related regulation of the kynurenine pathway: Relevance to neuropsychiatric and degenerative disorders. Neuropharmacology 2015; 112:307-323. [PMID: 26690895 DOI: 10.1016/j.neuropharm.2015.12.004] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/02/2015] [Accepted: 12/08/2015] [Indexed: 02/08/2023]
Abstract
The kynurenine pathway (KP), which is activated in times of stress and infection has been implicated in the pathophysiology of neurodegenerative and psychiatric disorders. Activation of this tryptophan metabolising pathway results in the production of neuroactive metabolites which have the potential to interfere with normal neuronal functioning which may contribute to altered neuronal transmission and the emergence of symptoms of these brain disorders. This review investigates the involvement of the KP in a range of neurological disorders, examining recent in vitro, in vivo and clinical discoveries highlights evidence to indicate that the KP is a potential therapeutic target in both neurodegenerative and stress-related neuropsychiatric disorders. Furthermore, this review identifies gaps in our knowledge with regard to this field which are yet to be examined to lead to a more comprehensive understanding of the role of KP activation in brain health and disease. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'.
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Affiliation(s)
- Katherine O'Farrell
- Neuropsychopharmacology Research Group, School of Pharmacy and Pharmaceutical Sciences & Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland
| | - Andrew Harkin
- Neuropsychopharmacology Research Group, School of Pharmacy and Pharmaceutical Sciences & Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland; Neuroimmunology Research Group, Department of Physiology, School of Medicine & Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland.
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Forrest CM, McNair K, Pisar M, Khalil OS, Darlington LG, Stone TW. Altered hippocampal plasticity by prenatal kynurenine administration, kynurenine-3-monoxygenase (KMO) deletion or galantamine. Neuroscience 2015; 310:91-105. [PMID: 26365611 PMCID: PMC4642643 DOI: 10.1016/j.neuroscience.2015.09.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/11/2015] [Accepted: 09/07/2015] [Indexed: 11/16/2022]
Abstract
Glutamate receptors sensitive to N-methyl-D-aspartate (NMDA) are involved in embryonic brain development but their activity may be modulated by the kynurenine pathway of tryptophan metabolism which includes an agonist (quinolinic acid) and an antagonist (kynurenic acid) at these receptors. Our previous work has shown that prenatal inhibition of the pathway produces abnormalities of brain development. In the present study kynurenine and probenecid (both 100mg/kg, doses known to increase kynurenic acid levels in the brain) were administered to female Wistar rats on embryonic days E14, E16 and E18 of gestation and the litter was allowed to develop to post-natal day P60. Western blotting revealed no changes in hippocampal expression of several proteins previously found to be altered by inhibition of the kynurenine pathway including the NMDA receptor subunits GluN1, GluN2A and GluN2B, as well as doublecortin, Proliferating Cell Nuclear Antigen (PCNA), sonic hedgehog and unco-ordinated (unc)-5H1 and 5H3. Mice lacking the enzyme kynurenine-3-monoxygenase (KMO) also showed no changes in hippocampal expression of several of these proteins or the 70-kDa and 100-kDa variants of Disrupted in Schizophrenia-1 (DISC1). Electrical excitability of pyramidal neurons in the CA1 region of hippocampal slices was unchanged, as was paired-pulse facilitation and inhibition. Long-term potentiation was decreased in the kynurenine-treated rats and in the KMO(-/-) mice, but galantamine reversed this effect in the presence of nicotinic receptor antagonists, consistent with evidence that it can potentiate glutamate at NMDA receptors. It is concluded that interference with the kynurenine pathway in utero can have lasting effects on brain function of the offspring, implying that the kynurenine pathway is involved in the regulation of early brain development.
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Affiliation(s)
- C M Forrest
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - K McNair
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - M Pisar
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - O S Khalil
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - L G Darlington
- Ashtead Hospital, The Warren, Ashtead, Surrey KT21 2SB, UK
| | - T W Stone
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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Réus GZ, Jansen K, Titus S, Carvalho AF, Gabbay V, Quevedo J. Kynurenine pathway dysfunction in the pathophysiology and treatment of depression: Evidences from animal and human studies. J Psychiatr Res 2015; 68:316-28. [PMID: 26028548 PMCID: PMC4955923 DOI: 10.1016/j.jpsychires.2015.05.007] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 04/29/2015] [Accepted: 05/07/2015] [Indexed: 12/16/2022]
Abstract
Treatment-resistant depression affects up to 20% of individuals suffering from major depressive disorder (MDD). The medications currently available to treat depression, including serotonin re-uptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs), fail to produce adequate remission of depressive symptoms for a large number of patients. The monoamine hypothesis upon which these medications are predicated should be expanded and revised as research elucidates alternative mechanisms of depression and effective methods to treat the underlying pathologic consequences. Research into the role of tryptophan degradation and the kynurenine pathway in the setting of inflammation has brought new insight into potential etiologies of MDD. Further investigation into the connection between inflammatory mediators, tryptophan degradation, and MDD can provide many targets for novel antidepressant therapies. Thus, this review will highlight the role of the kynurenine pathway in the pathophysiology of depression, as well as a novel therapeutic target to classic and new modulators to treat depression based on findings from preclinical and clinical studies.
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Affiliation(s)
- Gislaine Z. Réus
- Center for Translational Psychiatry, Department of Psychiatry and Behavioral Sciences, The University of Texas Medical School at Houston, Houston, TX, USA,Laboratory of Neurosciences, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciúma, SC, Brazil,Corresponding author: Gislaine Z. Réus, PhD, Center for Experimental Models in Psychiatry, Department of Psychiatry and Behavioral Sciences, The University of Texas Medical School at Houston, 1941 East Road, Houston, TX 77054, USA. , Phone: +1 (713) 486 2653, Fax: +1 (713) 486 2553
| | - Karen Jansen
- Center for Translational Psychiatry, Department of Psychiatry and Behavioral Sciences, The University of Texas Medical School at Houston, Houston, TX, USA,Graduate Program in Health and Behavior, Catholic University of Pelotas, Pelotas, RS, Brazil
| | - Stephanie Titus
- Center for Translational Psychiatry, Department of Psychiatry and Behavioral Sciences, The University of Texas Medical School at Houston, Houston, TX, USA
| | - André F. Carvalho
- Department of Clinical Medicine and Translational Psychiatry Research Group, Faculty of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Vilma Gabbay
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - João Quevedo
- Center for Translational Psychiatry, Department of Psychiatry and Behavioral Sciences, The University of Texas Medical School at Houston, Houston, TX, USA,Laboratory of Neurosciences, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciúma, SC, Brazil
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Pershing ML, Bortz DM, Pocivavsek A, Fredericks PJ, Jørgensen CV, Vunck SA, Leuner B, Schwarcz R, Bruno JP. Elevated levels of kynurenic acid during gestation produce neurochemical, morphological, and cognitive deficits in adulthood: implications for schizophrenia. Neuropharmacology 2015; 90:33-41. [PMID: 25446576 PMCID: PMC4731221 DOI: 10.1016/j.neuropharm.2014.10.017] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 11/16/2022]
Abstract
The levels of kynurenic acid (KYNA), an endogenous negative modulator of alpha7 nicotinic acetylcholine receptors (α7nAChRs), are elevated in the brains of patients with schizophrenia (SZ). We reported that increases of brain KYNA in rats, through dietary exposure to its precursor kynurenine from embryonic day (ED)15 to postnatal day (PD) 21, result in neurochemical and cognitive deficits in adulthood. The present experiments focused on the effects of prenatal exposure to elevated kynurenine on measures of prefrontal excitability known to be impaired in SZ. Pregnant dams were fed a mash containing kynurenine (100 mg/day; progeny = EKYNs) from ED15 until ED22. Controls were fed an unadulterated mash (progeny = ECONs). The dietary loading procedure elevated maternal and fetal plasma kynurenine (2223% and 693% above controls, respectively) and increased fetal KYNA (forebrain; 500% above controls) on ED21. Elevations in forebrain KYNA disappeared after termination of the loading (PD2), but KYNA levels in the prefrontal cortex (PFC) were unexpectedly increased again when measured in adults (PD56-80; 75% above controls). We also observed changes in several markers of prefrontal excitability, including expression of the α7nAChR (22% and 17% reductions at PD2 and PD56-80), expression of mGluR2 (31% and 24% reductions at ED21 and PD56-80), dendritic spine density (11-14% decrease at PD56-80), subsensitive mesolimbic stimulation of glutamate release in PFC, and reversal/extra-dimensional shift deficits in the prefrontally-mediated set-shifting task. These results highlight the deleterious impact of elevated KYNA levels during sensitive periods of early development, which model the pathophysiological and cognitive deficits seen in SZ.
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Affiliation(s)
| | - David M Bortz
- Department of Psychology, The Ohio State University, Columbus, OH, USA
| | - Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland College of Medicine, Baltimore, MD, USA
| | | | | | - Sarah A Vunck
- Department of Psychology, The Ohio State University, Columbus, OH, USA
| | - Benedetta Leuner
- Department of Psychology, The Ohio State University, Columbus, OH, USA; Department of Neuroscience, The Ohio State University, Columbus, OH, USA
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland College of Medicine, Baltimore, MD, USA
| | - John P Bruno
- Department of Psychology, The Ohio State University, Columbus, OH, USA; Department of Neuroscience, The Ohio State University, Columbus, OH, USA.
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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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45
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Pisar M, Forrest CM, Khalil OS, McNair K, Vincenten MC, Qasem S, Darlington LG, Stone TW. Modified neocortical and cerebellar protein expression and morphology in adult rats following prenatal inhibition of the kynurenine pathway. Brain Res 2014; 1576:1-17. [DOI: 10.1016/j.brainres.2014.06.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 06/12/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
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Pocivavsek A, Thomas MAR, Elmer GI, Bruno JP, Schwarcz R. Continuous kynurenine administration during the prenatal period, but not during adolescence, causes learning and memory deficits in adult rats. Psychopharmacology (Berl) 2014; 231:2799-809. [PMID: 24590052 PMCID: PMC4074218 DOI: 10.1007/s00213-014-3452-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 01/07/2014] [Indexed: 12/12/2022]
Abstract
RATIONALE Cognitive dysfunctions, including deficits in hippocampus-mediated learning and memory, are core features of the psychopathology of schizophrenia (SZ). Increased levels of kynurenic acid (KYNA), an astrocyte-derived tryptophan metabolite and antagonist of α7 nicotinic acetylcholine and N-methyl-D-aspartate receptors, have been implicated in these cognitive impairments. OBJECTIVES Following recent suggestive evidence, the present study was designed to narrow the critical time period for KYNA elevation to induce subsequent cognitive deficits. METHODS KYNA levels were experimentally increased in rats (1) prenatally (embryonic day (ED) 15 to ED 22) or (2) during adolescence (postnatal day (PD) 42 to PD 49). The KYNA precursor kynurenine was added daily to wet mash fed to (1) dams (100 mg/day; control: ECon; kynurenine-treated: EKyn) or (2) adolescent rats (300 mg/kg/day; control: AdCon; kynurenine-treated: AdKyn). Upon termination of the treatment, all animals were fed normal chow until biochemical analysis and behavioral testing in adulthood. RESULTS On the last day of continuous kynurenine treatment, forebrain KYNA levels were significantly elevated (EKyn +472 %; AdKyn +470 %). KYNA levels remained increased in the hippocampus of adult EKyn animals (+54 %), but were unchanged in adult AdKyn rats. Prenatal, but not adolescent, kynurenine treatment caused significant impairments in two hippocampus-mediated behavioral tasks, passive avoidance and Morris water maze. CONCLUSIONS Collectively, these studies provide evidence that a continuous increase in brain KYNA levels during the late prenatal period, but not during adolescence, induces hippocampus-related cognitive dysfunctions later in life. Such increases may play a significant role in illnesses with known hippocampal pathophysiology, including SZ.
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Affiliation(s)
- Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland (USA)
| | - Marian A. R. Thomas
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland (USA)
| | - Greg I. Elmer
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland (USA)
| | - John P. Bruno
- Departments of Psychology and Neuroscience, The Ohio State University, Columbus, Ohio (USA)
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland (USA)
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Khalil OS, Pisar M, Forrest CM, Vincenten MCJ, Darlington LG, Stone TW. Prenatal inhibition of the kynurenine pathway leads to structural changes in the hippocampus of adult rat offspring. Eur J Neurosci 2014; 39:1558-71. [PMID: 24646396 PMCID: PMC4368408 DOI: 10.1111/ejn.12535] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/28/2014] [Accepted: 01/30/2014] [Indexed: 12/13/2022]
Abstract
Glutamate receptors for N-methyl-d-aspartate (NMDA) are involved in early brain development. The kynurenine pathway of tryptophan metabolism includes the NMDA receptor agonist quinolinic acid and the antagonist kynurenic acid. We now report that prenatal inhibition of the pathway in rats with 3,4-dimethoxy-N-[4-(3-nitrophenyl)thiazol-2-yl]benzenesulphonamide (Ro61-8048) produces marked changes in hippocampal neuron morphology, spine density and the immunocytochemical localisation of developmental proteins in the offspring at postnatal day 60. Golgi–Cox silver staining revealed decreased overall numbers and lengths of CA1 basal dendrites and secondary basal dendrites, together with fewer basal dendritic spines and less overall dendritic complexity in the basal arbour. Fewer dendrites and less complexity were also noted in the dentate gyrus granule cells. More neurons containing the nuclear marker NeuN and the developmental protein sonic hedgehog were detected in the CA1 region and dentate gyrus. Staining for doublecortin revealed fewer newly generated granule cells bearing extended dendritic processes. The number of neuron terminals staining for vesicular glutamate transporter (VGLUT)-1 and VGLUT-2 was increased by Ro61-8048, with no change in expression of vesicular GABA transporter or its co-localisation with vesicle-associated membrane protein-1. These data support the view that constitutive kynurenine metabolism normally plays a role in early embryonic brain development, and that interfering with it has profound consequences for neuronal structure and morphology, lasting into adulthood.
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Affiliation(s)
- Omari S Khalil
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow, G12 8QQ, UK
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