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A randomized cross-over trial to define neurophysiological correlates of AV-101 N-methyl-D-aspartate receptor blockade in healthy veterans. Neuropsychopharmacology 2021; 46:820-827. [PMID: 33318635 PMCID: PMC8027791 DOI: 10.1038/s41386-020-00917-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/22/2020] [Accepted: 11/13/2020] [Indexed: 12/03/2022]
Abstract
The kynurenine pathway (KP) is a strategic metabolic system that combines regulation of neuronal excitability via glutamate receptor function and neuroinflammation via other KP metabolites. This pathway has great promise in treatment of depression and suicidality. The KP modulator AV-101 (4-chlorokynurenine, 4-Cl-KYN), an oral prodrug of 7-chlorokynurenic acid (7-Cl-KYNA), an N-methyl-D-aspartate receptor (NMDAR) glycine site antagonist, and of 4-chloro-3-hydroxyanthranilic acid (4-Cl-3-HAA), a suppressor of NMDAR agonist quinolinic acid (QUIN), is a promising potential antidepressant that targets glutamate functioning via the KP. However, a recent placebo-controlled clinical trial of AV-101 in depression found negative results. This raises the question of whether AV-101 can penetrate the brain and engage the NMDAR and KP effectively. To address this problem, ten healthy US military veterans (mean age = 32.6 years ± 6.11; 1 female) completed a phase-1 randomized, double-blind, placebo-controlled, crossover study to examine dose-related effects of AV-101 (720 and 1440 mg) on NMDAR engagement measured by γ-frequency band auditory steady-state response (40 Hz ASSR) and resting EEG. Linear mixed models revealed that 1440 mg AV-101, but not 720 mg, increased 40 Hz ASSR and 40 Hz ASSR γ-inter-trial phase coherence relative to placebo. AV-101 also increased 4-Cl-KYN, 7-Cl-KYNA, 4-Cl-3-HAA, 3-HAA, and KYNA in a dose-dependent manner, without affecting KYN and QUIN. AV-101 was safe and well tolerated. These results corroborate brain target engagement of 1440 mg AV-101 in humans, consistent with blockade of interneuronal NMDAR blockade. Future studies should test higher doses of AV-101 in depression. Suicidal behavior, which has been associated with high QUIN and low KYNA, is also a potential target for AV-101.
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Zlatopolskiy BD, Zischler J, Schäfer D, Urusova EA, Guliyev M, Bannykh O, Endepols H, Neumaier B. Discovery of 7-[18F]Fluorotryptophan as a Novel Positron Emission Tomography (PET) Probe for the Visualization of Tryptophan Metabolism in Vivo. J Med Chem 2017; 61:189-206. [DOI: 10.1021/acs.jmedchem.7b01245] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Boris D. Zlatopolskiy
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
| | - Johannes Zischler
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Dominique Schäfer
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Elizaveta A. Urusova
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
| | - Mehrab Guliyev
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Olesia Bannykh
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Heike Endepols
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
- Department
of Nuclear Medicine, University Clinic Cologne, Cologne 50937, Germany
| | - Bernd Neumaier
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
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3
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Stone TW, Forrest CM, Darlington LG. Kynurenine pathway inhibition as a therapeutic strategy for neuroprotection. FEBS J 2012; 279:1386-97. [DOI: 10.1111/j.1742-4658.2012.08487.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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4
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Kim Y, Han S. Synthesis of L‐6‐Chloropyrroloindoline of Chloptosin Cyclohexapeptide. SYNTHETIC COMMUN 2011. [DOI: 10.1081/scc-200026636] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Young‐Ah Kim
- a Department of Chemistry and Division of Molecular Life Sciences , Ewha Womans University , Seoul, 120‐750, Korea
| | - So‐Yeop Han
- a Department of Chemistry and Division of Molecular Life Sciences , Ewha Womans University , Seoul, 120‐750, Korea
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5
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Abstract
Alzheimer’s disease (AD) is one of the major causes of dementia. The pathogenesis of the disease is not entirely understood, but the amyloid β peptide (Aβ) and the formation of senile plaques seem to play pivotal roles. Oligomerization of the Aβ is thought to trigger a cascade of events, including oxidative stress, glutamate excitotoxicity and inflammation. The kynurenine (KYN) pathway is the major route for the metabolism of the essential amino acid tryptophan. Some of the metabolites of this pathway, such as 3-hydroxykynurenine and quinolinic acid, are known to have neurotoxic properties, whereas others, such as kynurenic acid, are putative neuroprotectants. Among other routes, the KYN pathway has been shown to be involved in AD pathogenesis, and connections to other known mechanisms have also been demonstrated. Oxidative stress, glutamate excitotoxicity and the neuroinflammation involved in AD pathogenesis have been revealed to be connected to the KYN pathway. Intervention at these key steps may serve as the aim of potential therapy.
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Affiliation(s)
- Zsigmond Tamas Kincses
- Department of Neurology, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
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6
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Yamada A, Akimoto H, Kagawa S, Guillemin GJ, Takikawa O. Proinflammatory cytokine interferon-gamma increases induction of indoleamine 2,3-dioxygenase in monocytic cells primed with amyloid beta peptide 1-42: implications for the pathogenesis of Alzheimer's disease. J Neurochem 2009; 110:791-800. [PMID: 19457071 DOI: 10.1111/j.1471-4159.2009.06175.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme of the kynurenine pathway of tryptophan metabolism, ultimately leading to production of the excitotoxin quinolinic acid (QUIN) by monocytic cells. In the Tg2576 mouse model of Alzheimer's disease, systemic inflammation induced by lipopolysaccharide leads to an increase in IDO expression and QUIN production in microglia surrounding amyloid plaques. We examined whether the IDO over-expression in microglia could be mediated by brain proinflammatory cytokines induced during the peripheral inflammation using THP-1 cells and peripheral blood mononuclear cells (PBMC) as models for microglia. THP-1 cells pre-treated with 5-25 muM amyloid beta peptide (Abeta) (1-42) but not with Abeta (1-40) or Abeta (25-35) became an activated state as indicated by their morphological changes and enhanced adhesiveness. IDO expression was only slightly increased in the reactive cells but strongly enhanced following treatment with proinflammatory cytokine interferon-gamma (IFN-gamma) but not with interleukin-1beta, tumor necrosis factor-alpha, or interleukin-6 at 100 U/mL. The concomitant addition of Abeta (1-42) with IFN-gamma was totally ineffective, indicating that Abeta pre-treatment is prerequisite for a high IDO expression. The priming effect of Abeta (1-42) for the IDO induction was also observed for PBMC. These findings suggest that IFN-gamma induces IDO over-expression in the primed microglia surrounding amyloid plaques.
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Affiliation(s)
- Akiko Yamada
- National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Aichi, Japan
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7
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Kita T, Morrison PF, Heyes MP, Markey SP. Effects of systemic and central nervous system localized inflammation on the contributions of metabolic precursors to the L-kynurenine and quinolinic acid pools in brain. J Neurochem 2002; 82:258-68. [PMID: 12124427 DOI: 10.1046/j.1471-4159.2002.00955.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
L-Kynurenine and quinolinic acid are neuroactive L-tryptophan-kynurenine pathway metabolites of potential importance in pathogenesis and treatment of neurologic disease. To identify precursors of these metabolites in brain, [(2)H(3) ]-L-kynurenine was infused subcutaneously by osmotic pump into three groups of gerbils: controls, CNS-localized immune-activated, and systemically immune-activated. The specific activity of L-kynurenine and quinolinate in blood, brain and systemic tissues at equilibrium was then quantified by mass spectrometry and the results applied to a model of metabolism to differentiate the relative contributions of various metabolic precursors. In control gerbils, 22% of L-kynurenine in brain was derived via local synthesis from L-tryptophan/formylkynurenine versus 78% from L-kynurenine from blood. Quinolinate in brain was derived from several sources, including: local tissue L-tryptophan/formylkynurenine (10%), blood L-kynurenine (35%), blood 3-hydroxykynurenine/3-hydroxyanthranilate (7%), and blood quinolinate (48%). After systemic immune-activation, however, L-kynurenine in brain was derived exclusively from blood, whereas quinolinate in brain was derived from three sources: blood L-kynurenine (52%), blood 3-hydroxykynurenine or 3-hydroxyanthranilate (8%), and blood quinolinate (40%). During CNS-localized immune activation, > 98% of both L-kynurenine and quinolinate were derived via local synthesis in brain. Thus, immune activation and its site determine the sources from which L-kynurenine and quinolinate are synthesized in brain. Successful therapeutic modulation of their concentrations must take into account the metabolic and compartment sources.
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Affiliation(s)
- Tomoyuki Kita
- Laboratory of Neurotoxicology, National Institute of Mental Health, Bethesda, Maryland 20892, USA
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8
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Abstract
In just under 20 years the kynurenine family of compounds has developed from a group of obscure metabolites of the essential amino acid tryptophan into a source of intensive research, with postulated roles for quinolinic acid in neurodegenerative disorders, most especially the AIDS-dementia complex and Huntington's disease. One of the kynurenines, kynurenic acid, has become a standard tool for use in the identification of glutamate-releasing synapses, and has been used as the parent for several groups of compounds now being developed as drugs for the treatment of epilepsy and stroke. The kynurenines represent a major success in translating a basic discovery into a source of clinical understanding and therapeutic application, with around 3000 papers published on quinolinic acid or kynurenic acid since the discovery of their effects in 1981 and 1982. This review concentrates on some of the recent work most directly relevant to the understanding and applications of kynurenines in medicine.
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Affiliation(s)
- T W Stone
- Institute of Biomedical and Life Sciences, University West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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9
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Abstract
In most tissues, including brain, a major proportion of the tryptophan which is not used for protein synthesis is metabolised along the kynurenine pathway. Long regarded as the route by which many mammals generate adequate amounts of the essential co-factor nicotinamide adenine dinucleotide, two components of the pathway are now known to have marked effects on neurones. Quinolinic acid is an agonist at the N-methyl-D-aspartate sensitive subtype of glutamate receptors in the brain, while kynurenic acid is an antagonist and, thus, a potential neuroprotectant. A third kynurenine, 3-hydroxykynurenine, is involved in the generation of free radicals which can also damage neurones. Quinolinic acid is increasingly implicated in neurodegenerative disorders, most especially the AIDS-dementia complex and Huntington's disease, while kynurenic acid has become a standard for the identification of glutamate-releasing synapses, and has been used as the parent for several groups of compounds now being developed as drugs for the treatment of epilepsy and stroke.
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Affiliation(s)
- T W Stone
- Institute of Biomedical & Life Sciences, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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Molnár-Perl I. Advances in the analysis of tryptophan and its related compounds by chromatography. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 467:801-16. [PMID: 10721133 DOI: 10.1007/978-1-4615-4709-9_102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Advances in the analysis of tryptophan,--(both in its free form and bound, alone or together with its metabolites),--has been compiled on the basis of the relevant papers published in the last 4-5 years, including author's experiences associated with the preparation of derivatives and with any of those conditions arising from the analytical procedure itself. The special requirements of various, tryptophan containing matrices were also taken into consideration (biological tissues or fluids, food and feed stuffs, etc). For the sake of completeness in addition to the most common HPLC/UV/F1 techniques, HPLC/MS, GC/MS, CE/UV/F1 and spectrophotometry will be also discussed.
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Affiliation(s)
- I Molnár-Perl
- Institute of Inorganic & Analytical Chemistry, L. Eötvös University, Budapest, Hungary.
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11
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Guidetti P, Wu HQ, Schwarcz R. In situ produced 7-chlorokynurenate provides protection against quinolinate- and malonate-induced neurotoxicity in the rat striatum. Exp Neurol 2000; 163:123-30. [PMID: 10785450 DOI: 10.1006/exnr.1999.7284] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Excitotoxic mechanisms may play a critical role in the pathophysiology of several neurological and psychiatric diseases. Excitatory amino acid receptor antagonists are therefore of great therapeutic interest, but untoward side effects often prevent their clinical use. Targeting the glycine coagonist site of the (NMDA) receptor may bypass these shortcomings. The present study was designed to evaluate the neuroprotective characteristics of l-4-chlorokynurenine (4-Cl-KYN), a synthetic compound which is enzymatically converted to the selective glycine/NMDA receptor antagonist 7-chlorokynurenate (7-Cl-KYNA). Using slow (2 h) intrastriatal infusions of the excitotoxins quinolinate (QUIN; 120 nmol) or malonate (6.8 micromol) as the experimental paradigm, the neuroprotective potency of 4-Cl-KYN was first compared with that of exogenous 7-Cl-KYNA, using glutamate decarboxylase activity as a lesion marker. One hundred and thirty-five nanomoles of the prodrug 4-Cl-KYN or 27 nmol 7-Cl-KYNA, the former used in a pre- and cotreatment regimen, were required to block QUIN or, less efficiently, malonate toxicity. In separate animals, the metabolic fate of this neuroprotective dose of 4-Cl-KYN was examined in vivo. In control striata, the treatment gave rise to 170 +/- 25 pmol 7-Cl-KYNA/mg protein, approximately six times less than an infusion of 27 nmol exogenous 7-Cl-KYNA, indicating greatly superior efficacy of the focally produced antagonist. Notably, the conversion of 4-Cl-KYN to 7-Cl-KYNA increased by 82% in the presence of QUIN. 4-Cl-KYN was also metabolized to 4-chloro-3-hydroxyanthranilate, an established, powerful inhibitor of QUIN synthesis. This unique pharmacological profile and the fact that the prodrug, unlike 7-Cl-KYNA, readily penetrates the blood-brain barrier suggest that 4-Cl-KYN may be exceptionally useful as an anti-excitotoxic agent.
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Affiliation(s)
- P Guidetti
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland 21228, USA
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12
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Stone TW. Development and therapeutic potential of kynurenic acid and kynurenine derivatives for neuroprotection. Trends Pharmacol Sci 2000; 21:149-54. [PMID: 10740291 DOI: 10.1016/s0165-6147(00)01451-6] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Manipulation of the kynurenine pathway of tryptophan metabolism has yielded a plethora of agents that are now being developed as neuroprotectants and anticonvulsants. This pathway is involved in the production of the excitotoxin quinolinic acid and the neuroprotectant kynurenic acid. Approaches used in the development of therapeutic agents include production of analogues or pro-drugs of kynurenic acid and inhibitors of the enzyme responsible for the synthesis of quinolinic acid. Indeed, analogues of the amino acid receptor antagonist kynurenic acid are now in, or are about to enter, clinical trials for stroke and related disorders. This review summarizes the mechanism of action of these various agents, the development of glutamate receptor antagonists from kynurenic acid and the range of their potential uses in neurology and psychiatry.
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Affiliation(s)
- T W Stone
- Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, Glasgow, UK.
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13
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Wu HQ, Lee SC, Schwarcz R. Systemic administration of 4-chlorokynurenine prevents quinolinate neurotoxicity in the rat hippocampus. Eur J Pharmacol 2000; 390:267-74. [PMID: 10708733 DOI: 10.1016/s0014-2999(00)00024-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The synthetic compound 4-chlorokynurenine has been shown to be enzymatically transaminated to the selective glycine(B) receptor antagonist 7-chlorokynurenate. Since 4-chlorokynurenine, in contrast to 7-chlorokynurenate, readily penetrates the blood-brain barrier, the present study evaluated its neuroprotective properties after systemic administration in rats. Intrahippocampal injection of the NMDA receptor agonist quinolinate (15 nmol/l microl) was used as the neurotoxic paradigm. Serum and hippocampal tissue measurements confirmed that 4-chlorokynurenine serves as an effective pro-drug of 7-chlorokynurenate both in the periphery and in the brain. These studies and complementary hippocampal microdialysis experiments compared the effects of single and repeated injections of 4-chlorokynurenine (50 or 200 mg/kg, intraperitoneal (i.p.), 10 min prior to an intrahippocampal quinolinate injection; or 50 mg/kg, i.p., 10 min before and 30, 120 and 360 min after quinolinate). With the multiple-dosing regimen, extracellular 7-chlorokynurenate levels in the hippocampus reached a maximum of approximately 750 nM 7 h after quinolinate and gradually decreased with a half-life of about 3 h. In contrast, a single injection of 200 mg/kg 4-chlorokynurenine resulted in a considerably shorter rise in extracellular 7-chlorokynurenate without yielding higher peak levels. In separate animals, repeated treatment with 50 mg/kg 4-chlorokynurenine, but not a single injection of 200 mg/kg of the pro-drug, provided total protection against quinolinate-induced excitotoxicity. These data suggest that a prolonged and functionally relevant blockade of hippocampal glycine(B) receptors can be achieved after the systemic administration of 4-chlorokynurenine.
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Affiliation(s)
- H Q Wu
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA.
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14
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Abstract
Strokes (intracranial thomboses or haemorrhaging) cause death and disability, but effective treatments are lacking. The metabolism of tryptophan leads to the generation of quinolinic acid, an agonist potentially neurotoxic at glutamate receptors, and kynurenic acid, an antagonist at the same population of receptors. The commercial development of the kynurenine pathway has included the use of analogues of kynurenic acid as antagonists at glutamate receptors. A second has been to use prodrugs of kynurenic acid or its analogues. Alternatively, it is proving possible to interfere directly with the kynurenine pathway to block the synthesis of quinolinic acid and promote the formation of kynurenic acid. This change yields neuroprotectant and anticonvulsant compounds.
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Affiliation(s)
- T W Stone
- Institute of Biomedical & Life Sciences, West Medical Building, University of Glasgow, Glasgow, UK.
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15
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Fornstedt-Wallin B, Lundström J, Fredriksson G, Schwarcz R, Luthman J. 3-Hydroxyanthranilic acid accumulation following administration of the 3-hydroxyanthranilic acid 3,4-dioxygenase inhibitor NCR-631. Eur J Pharmacol 1999; 386:15-24. [PMID: 10611459 DOI: 10.1016/s0014-2999(99)00683-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the kynurenine pathway of tryptophan metabolism, 3-hydroxyanthranilic acid is the substrate for formation of the excitotoxin quinolinic acid by 3-hydroxyanthranilic acid 3, 4-dioxygenase. This study was designed to characterize the effects on 3-hydroxyanthranilic acid after treatment with the 3-hydroxyanthranilic acid 3,4-dioxygenase inhibitor 4, 6-di-bromo-3-hydroxyanthranilic acid (NCR-631) in Sprague-Dawley rats. The blood plasma and brain concentrations of 3-hydroxyanthranilic acid were found to increase rapidly in a dose-dependent manner after gavage administration of NCR-631. However, the effect was relatively transient, with a decline in 3-hydroxyanthranilic acid levels already at 1h after NCR-631 treatment. Similar increases in plasma levels of 3-hydroxyanthranilic acid were observed following either gavage or parenteral (i.v. or s.c.) administration of NCR-631 (25 mg/kg). Only a minor enhancement of the NCR-631-induced increase in plasma 3-hydroxyanthranilic acid levels was found after sub-chronic treatment (25 mg/kg by gavage; 7 days, b.i.d.), suggesting a low propensity for altered 3-hydroxyanthranilic acid 3,4-dioxygenase activity following repeated inhibition. Administration of [14C]NCR-631 suggested 20 min initial plasma half life and an oral absorption around 50%. A dose of 250 mg/kg [14C]NCR-631 given by gavage provided plasma levels of almost 2 micromol/ml and a brain concentration of approximately 16 nmol/g, when analyzed 15 min after administration. Neither acute nor sub-chronic administration of NCR-631 caused any substantial effects on quinolinic acid levels in plasma or brain. Also, the plasma levels of kynurenic acid, another neuroactive kynurenine pathway metabolite, were unaffected by acute NCR-631 treatment. Moreover, the brain levels of the major cerebral tryptophan metabolites 5-hydroxytryptamine and 5-hydroxyindoleacetic acid remained unchanged following administration of NCR-631. Although reversible inhibition of 3-hydroxyanthranilic acid 3, 4-dioxygenase with NCR-631 in normal rats is insufficient to cause substantial changes in the levels of quinolinic acid or other important tryptophan metabolites, it causes a major accumulation of the substrate 3-hydroxyanthranilic acid.
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Affiliation(s)
- B Fornstedt-Wallin
- Department of Cell Biology, Preclinical R&D, Astra Arcus, S-151 85, Södertälje, Sweden
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16
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Abstract
Quinolinic acid (QUIN) levels are elevated in patients and animals suffering from chronic infectious diseases. In the present study, male Sprague-Dawley rats were used to test the anti-inflammatory effects of QUIN using the carrageenan (CGN)-induced paw edema assay and the CGN sponge assay. Results of these studies indicate that QUIN (30, 100 or 300 mg/kg i.p.) caused a reduction of carrageenan-induced inflammation by as much as 80% at the highest dose. Moreover, QUIN reduced exudate volume and inhibited leukocyte migration in the sponge granuloma assay. In another experiment, the anti-inflammatory activity of QUIN was eliminated in adrenalectomized rats. QUIN did not reduce edema caused by arachidonic acid, bradykinin or compound 48/80. Neither morphine nor naloxone altered the anti-inflammatory activity of QUIN. These results may suggest that QUIN exerts its anti-inflammatory activity through a direct action on neutrophils or vascular permeability.
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Affiliation(s)
- S O Heyliger
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee 32307, USA
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17
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Heyes MP, Saito K, Lackner A, Wiley CA, Achim CL, Markey SP. Sources of the neurotoxin quinolinic acid in the brain of HIV‐1‐infected patients and retrovirus‐infected macaques. FASEB J 1998. [DOI: 10.1096/fasebj.12.10.981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Melvyn P. Heyes
- Laboratory of NeurotoxicologyNational Institute of Mental Health Bethesda 20892 Maryland USA
| | - Kuniaki Saito
- Laboratory of NeurotoxicologyNational Institute of Mental Health Bethesda 20892 Maryland USA
| | - Andrew Lackner
- New England Regional Primate Research CenterHarvard Medical School Southborough 01772 Massachusetts USA
| | - Clayton A. Wiley
- Neuropathology DivisionPresbyterian‐University Hospital Pittsburgh 15213 Pennsylvania USA
| | - Cristian L. Achim
- Neuropathology DivisionPresbyterian‐University Hospital Pittsburgh 15213 Pennsylvania USA
| | - Sanford P. Markey
- Laboratory of NeurotoxicologyNational Institute of Mental Health Bethesda 20892 Maryland USA
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18
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Heyes MP, Saito K, Lackner A, Wiley CA, Achim CL, Markey SP. Sources of the neurotoxin quinolinic acid in the brain of HIV-1-infected patients and retrovirus-infected macaques. FASEB J 1998; 12:881-96. [PMID: 9657528 DOI: 10.1096/fasebj.12.10.881] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study investigated the sources of quinolinic acid, a neurotoxic tryptophan-kynurenine pathway metabolite, in the brain and blood of HIV-infected patients and retrovirus-infected macaques. In brain, quinolinic acid concentrations in HIV-infected patients were elevated by > 300-fold to concentrations that exceeded cerebrospinal fluid (CSF) by 8.9-fold. There were no significant correlations between elevated serum quinolinic acid levels with those in CSF and brain parenchyma. Because nonretrovirus-induced encephalitis confounds the interpretation of human postmortem data, rhesus macaques infected with retrovirus were used to examine the mechanisms of increased quinolinic acid accumulations and determine the relationships of quinolinic acid to encephalitits and systemic responses. The largest kynurenine pathway responses in brain were associated with encephalitis and were independent of systemic responses. CSF quinolinic acid levels were also elevated in all infected macaques, but particularly those with retrovirus-induced encephalitis. In contrast to the brain changes, there was no difference in any systemic measure between macaques with encephalitis vs. those without. Direct measures of the amount of quinolinic acid in brain derived from blood in a macaque with encephalitis showed that almost all quinolinic acid (>98%) was synthesized locally within the brain. These results demonstrate a role for induction of indoleamine-2,3dioxygenase in accelerating the local formation of quinolinic acid within the brain tissue, particularly in areas of encephalitis, rather than entry of quinolinic acid into the brain from the meninges or blood. Strategies to reduce QUIN production, targeted at intracerebral sites, are potential approaches to therapy.
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Affiliation(s)
- M P Heyes
- Laboratory of Neurotoxicology, National Institute of Mental Health, Bethesda, Maryland 20892, USA
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Heyes MP, Chen CY, Major EO, Saito K. Different kynurenine pathway enzymes limit quinolinic acid formation by various human cell types. Biochem J 1997; 326 ( Pt 2):351-6. [PMID: 9291104 PMCID: PMC1218677 DOI: 10.1042/bj3260351] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Substantial increases in the tryptophan-kynurenine pathway metabolites, l-kynurenine and the neurotoxin quinolinic acid, occur in human brain, blood and systemic tissues during immune activation. Studies in vitro have shown that not all human cells are capable of synthesizing quinolinate. To investigate further the mechanisms that limit l-kynurenine and quinolinate production, the activities of kynurenine pathway enzymes and the ability of different human cells to convert pathway intermediates into quinolinate were compared. Stimulation with interferon gamma substantially increased indoleamine 2,3-dioxygenase activity and L-kynurenine production in primary peripheral blood macrophages and fetal brains (astrocytes and neurons), as well as cell lines derived from macrophage/monocytes (THP-1), U373MG astrocytoma, SKHEP1 liver and lung (MRC-9). High activities of kynurenine 3-hydroxylase, kynureninase or 3-hydroxyanthranilate 3,4-dioxygenase were found in interferon-gamma-stimulated macrophages, THP-1 cells and SKHEP1 cells, and these cells made large amounts of quinolinate when supplied with L-tryptophan, L-kynurenine, 3-hydroxykynurenine or 3-hydroxyanthranilate. Quinolinate production by human fetal brain cultures and U373MG cells was restricted by the low activities of kynurenine 3-hydroxylase, kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase, and only small amounts of quinolinate were synthesized when cultures were supplied with L-tryptophan or 3-hydroxyanthranilate. In MRC-9 cells, quinolinate was produced only from 3-hydroxykynurenine and 3-hydroxyanthranilate, consistent with their low kynurenine 3-hydroxylase activity. The results are consistent with the notion that indoleamine 2,3-dioxygenase is an important regulatory enzyme in the production of L-kynurenine and quinolinate. Kynurenine 3-hydroxylase and, in some cells, kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase are important determinants of whether a cell can make quinolinate.
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Affiliation(s)
- M P Heyes
- Laboratory of Neurotoxicology, NIMH, Bethesda, MD 20892-1262, USA
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AIDS-associated neurological disorders. NEUROPHYSIOLOGY+ 1996. [DOI: 10.1007/bf02262781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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