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García-Lara L, Pérez-Severiano F, González-Esquivel D, Elizondo G, Segovia J. Absence of aryl hydrocarbon receptors increases endogenous kynurenic acid levels and protects mouse brain against excitotoxic insult and oxidative stress. J Neurosci Res 2015; 93:1423-33. [DOI: 10.1002/jnr.23595] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 03/27/2015] [Accepted: 04/06/2015] [Indexed: 01/08/2023]
Affiliation(s)
- Lucia García-Lara
- Departamento de Fisiología; Biofísica; y Neurociencias; Centro de Investigación y de Estudios Avanzados del IPN; México D.F. México
| | - Francisca Pérez-Severiano
- Departamento de Neuroquímica; Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez; México D.F. México
| | - Dinora González-Esquivel
- Departamento de Neuroquímica; Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez; México D.F. México
| | - Guillermo Elizondo
- Departamento de Biología Celular; Centro de Investigación y de Estudios Avanzados del IPN; México D.F. México
| | - José Segovia
- Departamento de Fisiología; Biofísica; y Neurociencias; Centro de Investigación y de Estudios Avanzados del IPN; México D.F. México
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Perkins AE, Fadel JR, Kelly SJ. The effects of postnatal alcohol exposure and galantamine on the context pre-exposure facilitation effect and acetylcholine efflux using in vivo microdialysis. Alcohol 2015; 49:193-205. [PMID: 25837482 DOI: 10.1016/j.alcohol.2015.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 01/05/2015] [Accepted: 01/23/2015] [Indexed: 12/12/2022]
Abstract
Fetal alcohol spectrum disorders (FASD) are characterized by damage to multiple brain regions, including the hippocampus, which is involved in learning and memory. The acetylcholine neurotransmitter system provides major input to the hippocampus and is a possible target of developmental alcohol exposure. Alcohol (3.0 g/kg/day) was administered via intubation to male rat pups (postnatal day [PD] 2-10; ethanol-treated [ET]). Controls received a sham intubation (IC) or no treatment (NC). Acetylcholine efflux was measured using in vivo microdialysis (PD 32-35). ET animals were not different at baseline, but had decreased K(+)/Ca(2+)-induced acetylcholine efflux compared to NC animals and an enhanced acetylcholine response to galantamine (acetylcholinesterase inhibitor; 2.0 mg/kg) compared to both control groups. A separate cohort of animals was tested in the context pre-exposure facilitation effect task (CPFE; PD 30-32) following postnatal alcohol exposure and administration of galantamine (2.0 mg/kg; PD 11-30). Neither chronic galantamine nor postnatal alcohol exposure influenced performance in the CPFE task. Using immunohistochemistry, we found that neither alcohol exposure nor behavioral testing significantly altered the density of vesicular acetylcholine transporter or alpha7 nicotinic acetylcholine receptor in the ventral hippocampus (CA1). In the medial septum, the average number of choline acetyltransferase (ChAT+) cells was increased in ET animals that displayed the context-shock association; there were no changes in IC and NC animals that learned the context-shock association or in any animals that were in the control task that entailed no learning. Taken together, these results indicate that the hippocampal acetylcholine system is significantly disrupted under conditions of pharmacological manipulations (e.g., galantamine) in alcohol-exposed animals. Furthermore, ChAT was up‑regulated in ET animals that learned the CPFE, which may account for their ability to perform this task. In sum, developmental alcohol exposure may disrupt learning and memory in adolescence via a cholinergic mechanism.
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Affiliation(s)
- Amy E Perkins
- Department of Psychology, University of South Carolina, 1512 Pendleton St., Columbia, SC 29208, USA
| | - Jim R Fadel
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, USA
| | - Sandra J Kelly
- Department of Psychology, University of South Carolina, 1512 Pendleton St., Columbia, SC 29208, USA; Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, USA.
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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: 67] [Impact Index Per Article: 7.4] [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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54
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DeAngeli NE, Todd TP, Chang SE, Yeh HH, Yeh PW, Bucci DJ. Exposure to Kynurenic Acid during Adolescence Increases Sign-Tracking and Impairs Long-Term Potentiation in Adulthood. Front Behav Neurosci 2015; 8:451. [PMID: 25610382 PMCID: PMC4285091 DOI: 10.3389/fnbeh.2014.00451] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/16/2014] [Indexed: 11/21/2022] Open
Abstract
Changes in brain reward systems are thought to contribute significantly to the cognitive and behavioral impairments of schizophrenia, as well as the propensity to develop co-occurring substance abuse disorders. Presently, there are few treatments for persons with a dual diagnosis and little is known about the neural substrates that underlie co-occurring schizophrenia and substance abuse. One goal of the present study was to determine if a change in the concentration of kynurenic acid (KYNA), a tryptophan metabolite that is increased in the brains of people with schizophrenia, affects reward-related behavior. KYNA is an endogenous antagonist of NMDA glutamate receptors and α7 nicotinic acetylcholine receptors, both of which are critically involved in neurodevelopment, plasticity, and behavior. In Experiment 1, rats were treated throughout adolescence with L-kynurenine (L-KYN), the precursor of KYNA. As adults, the rats were tested drug-free in an autoshaping procedure in which a lever was paired with food. Rats treated with L-KYN during adolescence exhibited increased sign-tracking behavior (lever pressing) when they were tested as adults. Sign-tracking is thought to reflect the lever acquiring incentive salience (motivational value) as a result of its pairing with reward. Thus, KYNA exposure may increase the incentive salience of cues associated with reward, perhaps contributing to an increase in sensitivity to drug-related cues in persons with schizophrenia. In Experiment 2, we tested the effects of exposure to KYNA during adolescence on hippocampal long-term potentiation (LTP). Rats treated with L-KYN exhibited no LTP after a burst of high-frequency stimulation that was sufficient to produce robust LTP in vehicle-treated rats. This finding represents the first demonstrated consequence of elevated KYNA concentration during development and provides insight into the basis for cognitive and behavioral deficits that result from exposure to KYNA during adolescence.
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Affiliation(s)
- Nicole E DeAngeli
- Department of Psychological and Brain Sciences, Dartmouth College , Hanover, NH , USA
| | - Travis P Todd
- Department of Psychological and Brain Sciences, Dartmouth College , Hanover, NH , USA
| | - Stephen E Chang
- Department of Psychological and Brain Sciences, Dartmouth College , Hanover, NH , USA
| | - Hermes H Yeh
- Department of Physiology and Neurobiology, Geisel School of Medicine, Dartmouth College , Hanover, NH , USA
| | - Pamela W Yeh
- Department of Physiology and Neurobiology, Geisel School of Medicine, Dartmouth College , Hanover, NH , USA
| | - David J Bucci
- Department of Psychological and Brain Sciences, Dartmouth College , Hanover, NH , 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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56
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Wonodi I, McMahon RP, Krishna N, Mitchell BD, Liu J, Glassman M, Hong LE, Gold JM. Influence of kynurenine 3-monooxygenase (KMO) gene polymorphism on cognitive function in schizophrenia. Schizophr Res 2014; 160:80-7. [PMID: 25464917 PMCID: PMC4516229 DOI: 10.1016/j.schres.2014.10.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 10/09/2014] [Accepted: 10/14/2014] [Indexed: 01/04/2023]
Abstract
BACKGROUND Cognitive deficits compromise quality of life and productivity for individuals with schizophrenia and have no effective treatments. Preclinical data point to the kynurenine pathway of tryptophan metabolism as a potential target for pro-cognitive drug development. We have previously demonstrated association of a kynurenine 3-monooxygenase (KMO) gene variant with reduced KMO gene expression in postmortem schizophrenia cortex, and neurocognitive endophenotypic deficits in a clinical sample. KMO encodes kynurenine 3-monooxygenase (KMO), the rate-limiting microglial enzyme of cortical kynurenine metabolism. Aberration of the KMO gene might be the proximal cause of impaired cortical kynurenine metabolism observed in schizophrenia. However, the relationship between KMO variation and cognitive function in schizophrenia is unknown. This study examined the effects of the KMO rs2275163C>T C (risk) allele on cognitive function in schizophrenia. METHODS We examined the association of KMO polymorphisms with general neuropsychological performance and P50 gating in a sample of 150 schizophrenia and 95 healthy controls. RESULTS Consistent with our original report, the KMO rs2275163C>T C (risk) allele was associated with deficits in general neuropsychological performance, and this effect was more marked in schizophrenia compared with controls. Additionally, the C (Arg452) allele of the missense rs1053230C>T variant (KMO Arg452Cys) showed a trend effect on cognitive function. Neither variant affected P50 gating. CONCLUSIONS These data suggest that KMO variation influences a range of cognitive domains known to predict functional outcome. Extensive molecular characterization of this gene would elucidate its role in cognitive function with implications for vertical integration with basic discovery.
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Affiliation(s)
- Ikwunga Wonodi
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Robert P. McMahon
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nithin Krishna
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Braxton D. Mitchell
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Judy Liu
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew Glassman
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - L. Elliot Hong
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James M. Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
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Koola MM, Buchanan RW, Pillai A, Aitchison KJ, Weinberger DR, Aaronson ST, Dickerson FB. Potential role of the combination of galantamine and memantine to improve cognition in schizophrenia. Schizophr Res 2014; 157:84-9. [PMID: 24878431 PMCID: PMC4099270 DOI: 10.1016/j.schres.2014.04.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 04/22/2014] [Accepted: 04/26/2014] [Indexed: 12/28/2022]
Abstract
The Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) and Treatment Units for Research on Neurocognition and Schizophrenia projects were designed to facilitate the development of new drugs for the treatment of cognitive impairments in people with schizophrenia. The MATRICS project identified three drug mechanisms of particular interest: dopaminergic, cholinergic, and glutamatergic. As a group, while people with schizophrenia have moderate cognitive impairment, it is the best predictor of long-term outcome. Unfortunately, there are no approved medications for cognitive impairment in this population. Hence, the development of new pharmacological approaches is critical for reducing illness-related disability. The combination of an acetylcholinesterase inhibitor (AChEI) and memantine is more effective than either medication alone to improve cognition in Alzheimer's dementia. Galantamine is not only an AChEI, but also a positive allosteric modulator of the α4β2 and α7 nicotinic receptors. Hypofunction of N-methyl-d-aspartate (NMDA) receptors has been implicated in the pathophysiology of cognitive symptoms in schizophrenia and hence memantine may positively impact cognition. Memantine decreases the tonic NMDA current and galantamine enhances the action potential mediated by a postsynaptic NMDA current. This results in an increased signal transmission; therefore, a greater signal-to-noise ratio occurs with the combination than memantine alone. Galantamine improves the α-amino-3-hydroxy-5-methyl-4-isoxazol-propionate (AMPA)-mediated signaling which could be neuroprotective and may improve memory coding. The combination of galantamine and memantine may be particularly effective in schizophrenia in order to increase the selective cognition enhancement produced by either medication alone. In the future, multitarget-directed ligands may play a role in the treatment of complex diseases like schizophrenia.
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Affiliation(s)
- Maju Mathew Koola
- Sheppard Pratt Health System, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Robert W. Buchanan
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Anilkumar Pillai
- Department of Psychiatry and Health Behavior, Georgia Regents University, Augusta, GA, USA
| | - Katherine J. Aitchison
- Department of Psychiatry and Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel R. Weinberger
- Lieber Institute for Brain Development, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Scott T. Aaronson
- Sheppard Pratt Health System, Baltimore, MD, USA,Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Faith B. Dickerson
- Sheppard Pratt Health System, Baltimore, MD, USA,Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
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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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59
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Hashimoto K. Targeting of NMDA receptors in new treatments for schizophrenia. Expert Opin Ther Targets 2014; 18:1049-63. [PMID: 24965576 DOI: 10.1517/14728222.2014.934225] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Wennström M, Nielsen HM, Orhan F, Londos E, Minthon L, Erhardt S. Kynurenic Acid levels in cerebrospinal fluid from patients with Alzheimer's disease or dementia with lewy bodies. Int J Tryptophan Res 2014; 7:1-7. [PMID: 24855376 PMCID: PMC4011721 DOI: 10.4137/ijtr.s13958] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 01/27/2014] [Accepted: 02/03/2014] [Indexed: 12/24/2022] Open
Abstract
Kynurenic acid (KYNA) is implicated in cognitive functions. Altered concentrations of the compound are found in serum and cerebrospinal fluid (CSF) of patients with Alzheimer’s disease (AD). Further studies to determine whether KYNA serves as a biomarker for cognitive decline and dementia progression are required. In this study, we measured CSF KYNA levels in AD patients (n = 19), patients with dementia with Lewy bodies (DLB) (n = 18), and healthy age-matched controls (Ctrls)) (n = 20) to further explore possible correlations between KYNA levels, cognitive decline, and well-established AD and inflammatory markers. Neither DLB patients nor AD patients showed significantly altered CSF KYNA levels compared to Ctrls. However, female AD patients displayed significantly higher KYNA levels compared to male AD patients, a gender difference not seen in the Ctrl or DLB group. Levels of KYNA significantly correlated with the AD-biomarker P-tau and the inflammation marker soluble intercellular adhesion molecule-1 (sICAM-1) in the AD patient group. No associations between KYNA and cognitive functions were found. Our study shows that, although KYNA was not associated with cognitive decline in AD or DLB patients, it may be implicated in AD-related hyperphosphorylation of tau and inflammation. Further studies on larger patient cohorts are required to understand the potential role of KYNA in AD and DLB.
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Affiliation(s)
- Malin Wennström
- Department of Clinical Sciences Malmö, Molecular Memory Research Unit, Lund University, The Wallenberg Lab, Malmö, Sweden
| | - Henrietta M Nielsen
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, FL, USA
| | - Funda Orhan
- Department of Physiology and Pharmacology Karolinska Institutet, Stockholm, Sweden
| | - Elisabet Londos
- Department of Clinical Sciences Malmö, Clinical Memory Research Unit, Lund University, The Memory Clinic at Skåne University Hospital (SUS), Malmö, Sweden
| | - Lennart Minthon
- Department of Clinical Sciences Malmö, Clinical Memory Research Unit, Lund University, The Memory Clinic at Skåne University Hospital (SUS), Malmö, Sweden
| | - Sophie Erhardt
- Department of Physiology and Pharmacology Karolinska Institutet, Stockholm, Sweden
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A systemically-available kynurenine aminotransferase II (KAT II) inhibitor restores nicotine-evoked glutamatergic activity in the cortex of rats. Neuropharmacology 2014; 82:41-8. [PMID: 24647121 DOI: 10.1016/j.neuropharm.2014.03.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 03/06/2014] [Accepted: 03/08/2014] [Indexed: 01/01/2023]
Abstract
Kynurenic acid (KYNA) is a tryptophan metabolite that acts in the brain as an endogenous antagonist at multiple receptors, including glutamate and α7 nicotinic acetylcholine receptors. Increased levels of KYNA have been demonstrated in the brain of patients with a range of neurocognitive disorders, including schizophrenia, and are hypothesized to contribute to cognitive symptoms. Reducing KYNA levels by administering inhibitors of enzymes of the kynurenine pathway, particularly kynurenine aminotransferase II (KAT II), has been proposed as a treatment for such cognitive impairments. Here we report that administration of a systemically available KAT II inhibitor, PF-04859989, restores glutamate release events ("transients") evoked by pressure ejections of nicotine into the prefrontal cortex of rats exhibiting elevated KYNA levels. Nicotine-evoked glutamatergic transients can be reliably evoked and recorded after repeated pressure ejections of nicotine over 4-5 h. Systemic administration of l-kynurenine (100 mg/kg; i.p.) significantly increased frontal cortical KYNA levels and greatly attenuated the amplitude of nicotine-evoked glutamatergic transients. Systemic administration of PF-04859989 30 min prior to administration of l-kynurenine, but not when administered 30 min after l-kynurenine, restored glutamatergic transients recorded up to 75 min after the administration of the KAT II inhibitor. Furthermore, the KAT II inhibitor significantly reversed l-kynurenine-induced elevations of brain KYNA levels. The KAT II inhibitor did not affect nicotine-evoked glutamatergic transients in rats not pre-treated with l-kynurenine. Because PF-04859989 restores evoked glutamate signaling it therefore is a promising therapeutic compound for benefiting the cognitive symptoms of schizophrenia and other disorders associated with elevated brain KYNA levels.
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Liu X, Holtze M, Powell SB, Terrando N, Larsson MK, Persson A, Olsson SK, Orhan F, Kegel M, Asp L, Goiny M, Schwieler L, Engberg G, Karlsson H, Erhardt S. Behavioral disturbances in adult mice following neonatal virus infection or kynurenine treatment--role of brain kynurenic acid. Brain Behav Immun 2014; 36:80-9. [PMID: 24140727 PMCID: PMC3947209 DOI: 10.1016/j.bbi.2013.10.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 09/25/2013] [Accepted: 10/11/2013] [Indexed: 12/31/2022] Open
Abstract
Exposure to infections in early life is considered a risk-factor for developing schizophrenia. Recently we reported that a neonatal CNS infection with influenza A virus in mice resulted in a transient induction of the brain kynurenine pathway, and subsequent behavioral disturbances in immune-deficient adult mice. The aim of the present study was to investigate a potential role in this regard of kynurenic acid (KYNA), an endogenous antagonist at the glycine site of the N-methyl-D-aspartic acid (NMDA) receptor and at the cholinergic α7 nicotinic receptor. C57BL/6 mice were injected i.p. with neurotropic influenza A/WSN/33 virus (2400 plaque-forming units) at postnatal day (P) 3 or with L-kynurenine (2×200 mg/kg/day) at P7-16. In mice neonatally treated with L-kynurenine prepulse inhibition of the acoustic startle, anxiety, and learning and memory were also assessed. Neonatally infected mice showed enhanced sensitivity to D-amphetamine-induced (5 mg/kg i.p.) increase in locomotor activity as adults. Neonatally L-kynurenine treated mice showed enhanced sensitivity to D-amphetamine-induced (5 mg/kg i.p.) increase in locomotor activity as well as mild impairments in prepulse inhibition and memory. Also, D-amphetamine tended to potentiate dopamine release in the striatum in kynurenine-treated mice. These long-lasting behavioral and neurochemical alterations suggest that the kynurenine pathway can link early-life infection with the development of neuropsychiatric disturbances in adulthood.
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Affiliation(s)
- Xicong Liu
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Maria Holtze
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Susan B Powell
- Department of Psychiatry, University of California San Diego, La Jolla, California, USA
| | - Niccolò Terrando
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Markus K. Larsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Anna Persson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Sara K. Olsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Funda Orhan
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Magdalena Kegel
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Linnea Asp
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Michel Goiny
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Lilly Schwieler
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Göran Engberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Karlsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sophie Erhardt
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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63
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Su YA, Huang RH, Wang XD, Li JT, Si TM. Impaired working memory by repeated neonatal MK-801 treatment is ameliorated by galantamine in adult rats. Eur J Pharmacol 2014; 725:32-9. [PMID: 24440172 DOI: 10.1016/j.ejphar.2014.01.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 12/23/2013] [Accepted: 01/08/2014] [Indexed: 01/27/2023]
Abstract
Early life blockade of the NMDA receptor by using MK-801, a non-competitive NMDA receptor antagonist, induces behavioral changes that mimic several features of schizophrenia. In the current study, we first examined the effects of neonatal MK-801 treatment in male Sprague-Dawley rats on locomotor activity, prepulse inhibition and spatial working memory in adolescence (postnatal day 35, PND35) and adulthood (PND63). Next, we investigated the effects of an acetylcholinesterase inhibitor, galantamine, on working memory deficits induced by MK-801 treatment. Rats were treated with either saline or MK-801 (0.25mg/kg twice daily) at PND 5-14, and the long-term behavioral effects were investigated. MK-801 treated rats showed moderate working memory impairments in adolescence but a pronounced deficit in adulthood. However, locomotion and prepulse inhibition at two life stages were not affected by this treatment. Systemic administration of galantamine (1mg/kg) 30 min before each training session significantly improved neonatal MK-801-induced working memory deficits in adulthood. In conclusion, these results suggest that the neonatal MK-801 treatment-induced selective working memory deficit is related to a change in brain cholinergic systems.
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Affiliation(s)
- Yun-Ai Su
- Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, PR China; Institute of Mental Health, Peking University, Beijing, PR China
| | - Run-Hu Huang
- Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, PR China; Institute of Mental Health, Peking University, Beijing, PR China; Shanxi Dayi Hospital, Taiyuan, Shanxi Province, PR China
| | - Xiao-Dong Wang
- Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, PR China; Institute of Mental Health, Peking University, Beijing, PR China
| | - Ji-Tao Li
- Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, PR China; Institute of Mental Health, Peking University, Beijing, PR China
| | - Tian-Mei Si
- Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, PR China; Institute of Mental Health, Peking University, Beijing, PR China.
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64
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Forrest C, Khalil O, Pisar M, McNair K, Kornisiuk E, Snitcofsky M, Gonzalez N, Jerusalinsky D, Darlington L, Stone T. Changes in synaptic transmission and protein expression in the brains of adult offspring after prenatal inhibition of the kynurenine pathway. Neuroscience 2013; 254:241-59. [DOI: 10.1016/j.neuroscience.2013.09.034] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 09/17/2013] [Indexed: 10/26/2022]
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65
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Iaccarino HF, Suckow RF, Xie S, Bucci DJ. The effect of transient increases in kynurenic acid and quinolinic acid levels early in life on behavior in adulthood: Implications for schizophrenia. Schizophr Res 2013; 150:392-7. [PMID: 24091034 PMCID: PMC3844520 DOI: 10.1016/j.schres.2013.09.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/06/2013] [Accepted: 09/11/2013] [Indexed: 10/26/2022]
Abstract
Kynurenic acid is a tryptophan metabolite that is synthesized and released in the brain by astrocytes and acts as an antagonist of nicotinic acetylcholine receptors and N-methyl-d-aspartate glutamate receptors, both of which are critically involved in cognition as well as neural plasticity and brain development. The concentration of kynurenic acid is increased in the brains of persons with schizophrenia and this increase has been implicated in the cognitive and social impairments associated with the disease. In addition, growing evidence suggests that the increase in kynurenic acid may begin early in life. For example, exposure to influenza A virus during development results in a transient increase in kynurenic acid concentration that could disrupt normal brain development and lead to cognitive deficits later in life. Changes in kynurenic acid may thus provide a link between developmental exposure to viruses and the increased risk of subsequently developing schizophrenia. To test this, we mimicked the effects of influenza A exposure by treating rats with kynurenine, the precursor of kynurenic acid, on postnatal days 7-10. We observed a transient increase in both kynurenic acid and quinolinic acid during treatment. When rats were subsequently behaviorally tested as adults, those previously treated with kynurenine exhibited decreased social behavior and locomotor activity. In contrast, attentional function and fear conditioning were not affected. Together with other recent findings, these data have several implications for understanding how viral-induced changes in tryptophan metabolism during development may contribute to schizophrenia-related symptoms later in life.
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Affiliation(s)
- Hannah F. Iaccarino
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755
| | | | - Shan Xie
- Nathan Kline Institute, Orangeburg, New York 10962
| | - David J. Bucci
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755
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66
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Ratnayake U, Quinn T, Walker DW, Dickinson H. Cytokines and the neurodevelopmental basis of mental illness. Front Neurosci 2013; 7:180. [PMID: 24146637 PMCID: PMC3797953 DOI: 10.3389/fnins.2013.00180] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 09/19/2013] [Indexed: 11/21/2022] Open
Abstract
Epidemiological studies suggest that prenatal exposure to different types of viral or bacterial infections may be associated with similar outcomes; i.e., an increased risk of mental illness disorders in the offspring. Infections arising from various causes have similar debilitating effects in later life, suggesting that the exact pathogen may not be the critical factor in determining the neurological and cognitive outcome in the offspring. Instead, it is thought that response of the innate immune system, specifically the increased production of inflammatory cytokines, may be the critical mediator in altering fetal brain development pre-disposing the offspring to mental illness disorders later in life. Inflammatory cytokines are essential for normal brain development. Factors such as the site of cytokine production, a change in balance between anti- and pro- inflammatory cytokines, placental transfer of cytokines, the effects of cytokines on glial cells, and the effects of glucocorticoids are important when evaluating the impact of maternal infection on fetal brain development. Although it is clear that cytokines are altered in the fetal brain following maternal infection, further evidence is required to determine if cytokines are the critical factor that alters the trajectory of brain development, subsequently leading to postnatal behavioral and neurological abnormalities.
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Affiliation(s)
- Udani Ratnayake
- Ritchie Centre, Monash Institute of Medical Research, Monash University Clayton, Australia
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67
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Jenkins TA. Perinatal complications and schizophrenia: involvement of the immune system. Front Neurosci 2013; 7:110. [PMID: 23805069 PMCID: PMC3691516 DOI: 10.3389/fnins.2013.00110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 06/01/2013] [Indexed: 11/13/2022] Open
Abstract
The neurodevelopmental hypothesis of schizophrenia suggests that, at least in part, events occurring within the intrauterine or perinatal environment at critical times of brain development underlies emergence of the psychosis observed during adulthood, and brain pathologies that are hypothesized to be from birth. All potential risks stimulate activation of the immune system, and are suggested to act in parallel with an underlying genetic liability, such that an imperfect regulation of the genome mediates these prenatal or early postnatal environmental effects. Epidemiologically based animal models looking at environment and with genes have provided us with a wealth of knowledge in the understanding of the pathophysiology of schizophrenia, and give us the best possibility for interventions and treatments for schizophrenia.
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Affiliation(s)
- Trisha A Jenkins
- School of Medical Sciences, Health Innovations Research Institute, RMIT University Bundoora, VIC, Australia
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68
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Wallace T, Bertrand D. Importance of the nicotinic acetylcholine receptor system in the prefrontal cortex. Biochem Pharmacol 2013; 85:1713-20. [DOI: 10.1016/j.bcp.2013.04.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/29/2013] [Accepted: 04/01/2013] [Indexed: 11/27/2022]
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