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Bean L, Bose PK, Rani A, Kumar A. Serine racemase expression profile in the prefrontal cortex and hippocampal subregions during aging in male and female rats. Aging (Albany NY) 2024; 16:8402-8416. [PMID: 38761177 PMCID: PMC11164512 DOI: 10.18632/aging.205841] [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: 12/27/2023] [Accepted: 04/10/2024] [Indexed: 05/20/2024]
Abstract
Aging is associated with a decrease in N-methyl-D-aspartate (NMDA) receptor function, which is critical for maintaining synaptic plasticity, learning, and memory. Activation of the NMDA receptor requires binding of the neurotransmitter glutamate and also the presence of co-agonist D-serine at the glycine site. The enzymatic conversion of L-serine to D-serine is facilitated by the enzyme serine racemase (SR). Subsequently, SR plays a pivotal role in regulating NMDA receptor activity, thereby impacting synaptic plasticity and memory processes in the central nervous system. As such, age-related changes in the expression of SR could contribute to decreased NMDA receptor function. However, age-associated changes in SR expression levels in the medial and lateral prefrontal cortex (mPFC, lPFC), and in the dorsal hippocampal subfields, CA1, CA3, and dentate gyrus (DG), have not been thoroughly elucidated. Therefore, the current studies were designed to determine the SR expression profile, including protein levels and mRNA, for these regions in aged and young male and female Fischer-344 rats. Our results demonstrate a significant reduction in SR expression levels in the mPFC and all hippocampal subfields of aged rats compared to young rats. No sex differences were observed in the expression of SR. These findings suggest that the decrease in SR levels may play a role in the age-associated reduction of NMDA receptor function in brain regions crucial for cognitive function and synaptic plasticity.
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Affiliation(s)
- Linda Bean
- Department of Anatomy, Cell Biology, and Physiology, IU School of Medicine, Indianapolis, IN 46201, USA
| | - Prodip K. Bose
- Brain Rehabilitation Research Center, Malcom Randall Department of Veterans Affairs Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32607, USA
- Department of Anesthesiology and Department of Neurology at the College of Medicine, University of Florida, FL 32607, USA
| | - Asha Rani
- Department of Neuroscience, The McKnight Brain Institute, University of Florida, Gainesville, FL 32607, USA
| | - Ashok Kumar
- Department of Neuroscience, The McKnight Brain Institute, University of Florida, Gainesville, FL 32607, USA
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Gothe NP, Erlenbach E, Garcia V, Malani R, Voss S, Camacho PB, McAuley E, Burd N, Sutton BP, Damoiseaux JS. Yoga, aerobic and stretching exercise effects on neurocognition: Randomized controlled trial protocol. Contemp Clin Trials 2023; 131:107240. [PMID: 37244365 PMCID: PMC10527553 DOI: 10.1016/j.cct.2023.107240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/09/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
As the global population ages, the prevalence of cognitive decline and dementia is expected to rise, creating a significant health and economic burden. The purpose of this trial is to rigorously test, for the first time, the efficacy of yoga training as a physical activity intervention to mitigate age-related cognitive decline and impairment. We are conducting a 6-month randomized controlled trial (RCT) of exercise among 168 middle aged and older adults to compare the efficacy of yoga vs. aerobic exercise on cognitive function, brain structure and function, cardiorespiratory fitness, and circulating inflammatory and molecular markers. Using a single-blind, three arm RCT, 168 older adults ages 55-79 will be assigned to either: a Hatha yoga group, an aerobic exercise group or a stretching-toning active control group. Participants will engage in hour long group exercise 3x/week for 6-months. A comprehensive neurocognitive test battery, brain imaging, cardiovascular fitness test, and a blood draw will take place at baseline; end of the 6-month intervention, and at 12-month follow-up. Our primary outcomes of interest are brain regions, such as hippocampal volume and prefrontal cortex, and cognitive functions, such as episodic memory, working memory and executive functions, that are typically affected by aging and Alzheimer's disease. Not only will this RCT test whether yoga is a means to mitigate age-related cognitive decline, but it may also offer an alternative to aerobic exercise, which could be particularly appealing to older adults with compromised physical functioning. ClinicalTrials.gov Identifier: NCT04323163.
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Affiliation(s)
- Neha P Gothe
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana Champaign, Urbana, IL, USA; Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA.
| | - Emily Erlenbach
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Veronica Garcia
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Revati Malani
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Stephanie Voss
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Paul B Camacho
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana Champaign, Urbana, IL, USA
| | - Edward McAuley
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana Champaign, Urbana, IL, USA
| | - Nicholas Burd
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Bradley P Sutton
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana Champaign, Urbana, IL, USA
| | - Jessica S Damoiseaux
- Institute of Gerontology, Department of Psychology, Wayne State University, Detroit, MI, USA
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Yegla B, Rani A, Kumar A. Viral vector-mediated upregulation of serine racemase expression in medial prefrontal cortex improves learning and synaptic function in middle age rats. Aging (Albany NY) 2023; 15:2433-2449. [PMID: 37052995 PMCID: PMC10120901 DOI: 10.18632/aging.204652] [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: 01/19/2023] [Accepted: 04/03/2023] [Indexed: 04/14/2023]
Abstract
An age-associated decrease in N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic function contributes to impaired synaptic plasticity and is associated with cognitive impairments. Levels of serine racemase (SR), an enzyme that synthesizes D-serine, an NMDAR co-agonist, decline with age. Thus, enhancing NMDAR function via increased SR expression in middle age, when subtle declines in cognition emerge, was predicted to enhance performance on a prefrontal cortex-mediated task sensitive to aging. Middle-aged (~12 mo) male Fischer-344 rats were injected bilaterally in the medial prefrontal cortex (mPFC) with viral vector (LV), SR (LV-SR) or control (LV-GFP). Rats were trained on the operant attentional set-shift task (AST) to examine cognitive flexibility and attentional function. LV-SR rats exhibited a faster rate of learning compared to controls during visual discrimination of the AST. Extradimensional set shifting and reversal were not impacted. Immunohistochemical analyses demonstrated that LV-SR significantly increased SR expression in the mPFC. Electrophysiological characterization of synaptic transmission in the mPFC slices obtained from LV-GFP and LV-SR animals indicated a significant increase in isolated NMDAR-mediated synaptic responses in LV-SR slices. Thus, results of the current study demonstrated that prefrontal SR upregulation in middle age rats can improve learning of task contingencies for visual discrimination and increase glutamatergic synaptic transmission, including NMDAR activity.
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Affiliation(s)
- Brittney Yegla
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Asha Rani
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
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Liu H, Li Y, Peng T, Xue S. Transmembrane potential, an indicator in situ reporting cellular senescence and stress response in plant tissues. PLANT METHODS 2023; 19:27. [PMID: 36945027 PMCID: PMC10029184 DOI: 10.1186/s13007-023-01006-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Plant cells usually sustain a stable membrane potential due to influx and/or efflux of charged ions across plasma membrane. With the growth and development of plants, different tissues and cells undergo systemic or local programmed decline. Whether the membrane potential of plasma membrane could report senescence signal of plant tissues and cells is unclear. RESULTS We applied a maneuverable transmembrane potential (TMP) detection method with patch-clamp setup to examine the senescence signal of leaf tissue cells in situ over the whole life cycle in Arabidopsis thaliana. The data showed that the TMPs of plant tissues and cells were varied at different growth stages, and the change of TMP was higher at the vegetative growth stage than at the reproductive stage of plant growth. The distinct change of TMP was detectable between the normal and the senescent tissues and cells in several plant species. Moreover, diverse abiotic stimuli, such as heat stress, hyperpolarized the TMP in a short time, followed by depolarized membrane potential with the senescence occurring. We further examined the TMP of plant chloroplasts, which also indicates the senescence signal in organelles. CONCLUSIONS This convenient TMP detection method can report the senescence signal of plant tissues and cells, and can also indicate the potential of plant tolerance to environmental stress.
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Affiliation(s)
- Hai Liu
- College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yufei Li
- College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ting Peng
- College of Agriculture, Guizhou University, Guiyang, 550025, China
| | - Shaowu Xue
- College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
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Wu Y, Tang L, Huang H, Yu Q, Hu B, Wang G, Ge F, Yin T, Li S, Yu X. Phosphoglycerate dehydrogenase activates PKM2 to phosphorylate histone H3T11 and attenuate cellular senescence. Nat Commun 2023; 14:1323. [PMID: 36899022 PMCID: PMC10006232 DOI: 10.1038/s41467-023-37094-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 02/27/2023] [Indexed: 03/12/2023] Open
Abstract
Vascular endothelial cells (ECs) senescence correlates with the increase of cardiovascular diseases in ageing population. Although ECs rely on glycolysis for energy production, little is known about the role of glycolysis in ECs senescence. Here, we report a critical role for glycolysis-derived serine biosynthesis in preventing ECs senescence. During senescence, the expression of serine biosynthetic enzyme PHGDH is significantly reduced due to decreased transcription of the activating transcription factor ATF4, which leads to reduction of intracellular serine. PHGDH prevents premature senescence primarily by enhancing the stability and activity of pyruvate kinase M2 (PKM2). Mechanistically, PHGDH interacts with PKM2, which prevents PCAF-catalyzed PKM2 K305 acetylation and subsequent degradation by autophagy. In addition, PHGDH facilitates p300-catalyzed PKM2 K433 acetylation, which promotes PKM2 nuclear translocation and stimulates its activity to phosphorylate H3T11 and regulate the transcription of senescence-associated genes. Vascular endothelium-targeted expression of PHGDH and PKM2 ameliorates ageing in mice. Our findings reveal that enhancing serine biosynthesis could become a therapy to promote healthy ageing.
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Affiliation(s)
- Yinsheng Wu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China
| | - Lixu Tang
- School of Martial Arts, Wuhan Sports University, Wuhan, Hubei, 430079, China
| | - Han Huang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China
| | - Qi Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China
| | - Bicheng Hu
- The Central Laboratory, Wuhan No.1 Hospital, Wuhan, Hubei, 430022, China
| | - Gang Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China
| | - Feng Ge
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Tailang Yin
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, China.
| | - Shanshan Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China.
| | - Xilan Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China.
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Bender AR, Driver CC, Hertzog C, Raz N. Instructing Use of an Effective Strategy Improves Recognition Memory in Healthy Adults. J Gerontol B Psychol Sci Soc Sci 2023; 78:383-393. [PMID: 36130328 PMCID: PMC9985315 DOI: 10.1093/geronb/gbac144] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Age-related memory decrements correlate with metacognitive declines, including knowledge and deployment of effective mnemonic encoding strategies. However, whether imparting such strategy suffices for mitigating memory differences is unclear. METHOD In a longitudinal study of 276 healthy adults aged 18-79 years, we tested associative and working memory, and assessed beliefs regarding mnemonic strategies. Testing was repeated every 2 years, 5 times. Starting with the third occasion, we instructed participants to use an effective mnemonic strategy (sentence generation). Using continuous-time dynamic modeling, we assessed changes in the item and associative recognition, intervention effects, and their relations with age, sex, meta-memory beliefs, working memory, and metabolic health. RESULTS Younger age, better working memory, and stronger belief in effective mnemonic strategies predicted better recognition, whereas instructional intervention attenuated associative memory deficits, with some persistence over time. DISCUSSION The present findings show merely imparting effective strategies holds promise for mitigating age-related associative memory deficits.
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Affiliation(s)
- Andrew R Bender
- Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, Michigan, USA
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Charles C Driver
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
- Institute of Education, University of Zurich, Zurich, Switzerland
| | - Christopher Hertzog
- School of Psychology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Naftali Raz
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
- Department of Psychology, Stony Brook University, Stony Brook, New York, USA
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7
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Billard JM, Freret T. Improved NMDA Receptor Activation by the Secreted Amyloid-Protein Precursor-α in Healthy Aging: A Role for D-Serine? Int J Mol Sci 2022; 23:ijms232415542. [PMID: 36555191 PMCID: PMC9779005 DOI: 10.3390/ijms232415542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/30/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Impaired activation of the N-methyl-D-aspartate subtype of glutamate receptors (NMDAR) by D-serine is linked to cognitive aging. Whether this deregulation may be used to initiate pharmacological strategies has yet to be considered. To this end, we performed electrophysiological extracellular recordings at CA3/CA1 synapses in hippocampal slices from young and aged mice. We show that 0.1 nM of the soluble N-terminal recombinant fragment of the secreted amyloid-protein precursor-α (sAPPα) added in the bath significantly increased NMDAR activation in aged but not adult mice without impacting basal synaptic transmission. In addition, sAPPα rescued the age-related deficit of theta-burst-induced long-term potentiation. Significant NMDAR improvement occurred in adult mice when sAPPα was raised to 1 nM, and this effect was drastically reduced in transgenic mice deprived of D-serine through genetic deletion of the synthesizing enzyme serine racemase. Altogether, these results emphasize the interest to consider sAPPα treatment targeting D-serine-dependent NMDAR deregulation to alleviate cognitive aging.
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Nava-Gómez L, Calero-Vargas I, Higinio-Rodríguez F, Vázquez-Prieto B, Olivares-Moreno R, Ortiz-Retana J, Aranda P, Hernández-Chan N, Rojas-Piloni G, Alcauter S, López-Hidalgo M. AGING-ASSOCIATED COGNITIVE DECLINE IS REVERSED BY D-SERINE SUPPLEMENTATION. eNeuro 2022; 9:ENEURO.0176-22.2022. [PMID: 35584913 PMCID: PMC9186414 DOI: 10.1523/eneuro.0176-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 05/09/2022] [Accepted: 05/13/2022] [Indexed: 11/21/2022] Open
Abstract
Brain aging is a natural process that involves structural and functional changes that lead to cognitive decline, even in healthy subjects. This detriment has been associated with N-methyl-D-aspartate receptor (NMDAR) hypofunction due to a reduction in the brain levels of D-serine, the endogenous NMDAR co-agonist. However, it is not clear if D-serine supplementation could be used as an intervention to reduce or reverse age-related brain alterations. In the present work, we aimed to analyze the D-serine effect on aging-associated alterations in cellular and large-scale brain systems that could support cognitive flexibility in rats. We found that D-serine supplementation reverts the age-related decline in cognitive flexibility, frontal dendritic spine density, and partially restored large-scale functional connectivity without inducing nephrotoxicity; instead, D-serine restored the thickness of the renal epithelial cells that were affected by age. Our results suggest that D-serine could be used as a therapeutic target to reverse age-related brain alterations.SIGNIFICANT STATEMENTAge-related behavioral changes in cognitive performance occur as a physiological process of aging. Then, it is important to explore possible therapeutics to decrease, retard or reverse aging effects on the brain. NMDA receptor hypofunction contributes to the aging-associated cognitive decline. In the aged brain, there is a reduction in the brain levels of the NMDAR co-agonist, D-Serine. However, it is unclear if chronic D-serine supplementation could revert the age-detriment in brain functions. Our results show that D-serine supplementation reverts the age-associated decrease in cognitive flexibility, functional brain connectivity, and neuronal morphology. Our findings raise the possibility that restoring the brain levels of D-serine could be used as a therapeutic target to recover brain alterations associated with aging.
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Affiliation(s)
- L Nava-Gómez
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla. UNAM
- Facultad de Medicina. UAQ
| | - I Calero-Vargas
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla. UNAM
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - F Higinio-Rodríguez
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla. UNAM
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - B Vázquez-Prieto
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla. UNAM
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - R Olivares-Moreno
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - J Ortiz-Retana
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - P Aranda
- Facultad de Ciencias Naturales, UAQ
| | | | - G Rojas-Piloni
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - S Alcauter
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, México
| | - M López-Hidalgo
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla. UNAM
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Chen S, Xu D, Fan L, Fang Z, Wang X, Li M. Roles of N-Methyl-D-Aspartate Receptors (NMDARs) in Epilepsy. Front Mol Neurosci 2022; 14:797253. [PMID: 35069111 PMCID: PMC8780133 DOI: 10.3389/fnmol.2021.797253] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
Epilepsy is one of the most common neurological disorders characterized by recurrent seizures. The mechanism of epilepsy remains unclear and previous studies suggest that N-methyl-D-aspartate receptors (NMDARs) play an important role in abnormal discharges, nerve conduction, neuron injury and inflammation, thereby they may participate in epileptogenesis. NMDARs belong to a family of ionotropic glutamate receptors that play essential roles in excitatory neurotransmission and synaptic plasticity in the mammalian CNS. Despite numerous studies focusing on the role of NMDAR in epilepsy, the relationship appeared to be elusive. In this article, we reviewed the regulation of NMDAR and possible mechanisms of NMDAR in epilepsy and in respect of onset, development, and treatment, trying to provide more evidence for future studies.
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Piubelli L, Murtas G, Rabattoni V, Pollegioni L. The Role of D-Amino Acids in Alzheimer's Disease. J Alzheimers Dis 2021; 80:475-492. [PMID: 33554911 DOI: 10.3233/jad-201217] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD), the main cause of dementia worldwide, is characterized by a complex and multifactorial etiology. In large part, excitatory neurotransmission in the central nervous system is mediated by glutamate and its receptors are involved in synaptic plasticity. The N-methyl-D-aspartate (NMDA) receptors, which require the agonist glutamate and a coagonist such as glycine or the D-enantiomer of serine for activation, play a main role here. A second D-amino acid, D-aspartate, acts as agonist of NMDA receptors. D-amino acids, present in low amounts in nature and long considered to be of bacterial origin, have distinctive functions in mammals. In recent years, alterations in physiological levels of various D-amino acids have been linked to various pathological states, ranging from chronic kidney disease to neurological disorders. Actually, the level of NMDA receptor signaling must be balanced to promote neuronal survival and prevent neurodegeneration: this signaling in AD is affected mainly by glutamate availability and modulation of the receptor's functions. Here, we report the experimental findings linking D-serine and D-aspartate, through NMDA receptor modulation, to AD and cognitive functions. Interestingly, AD progression has been also associated with the enzymes related to D-amino acid metabolism as well as with glucose and serine metabolism. Furthermore, the D-serine and D-/total serine ratio in serum have been recently proposed as biomarkers of AD progression. A greater understanding of the role of D-amino acids in excitotoxicity related to the pathogenesis of AD will facilitate novel therapeutic treatments to cure the disease and improve life expectancy.
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Affiliation(s)
- Luciano Piubelli
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Giulia Murtas
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Valentina Rabattoni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Loredano Pollegioni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
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Dyakin VV, Wisniewski TM, Lajtha A. Racemization in Post-Translational Modifications Relevance to Protein Aging, Aggregation and Neurodegeneration: Tip of the Iceberg. Symmetry (Basel) 2021; 13:455. [PMID: 34350031 PMCID: PMC8330555 DOI: 10.3390/sym13030455] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Homochirality of DNA and prevalent chirality of free and protein-bound amino acids in a living organism represents the challenge for modern biochemistry and neuroscience. The idea of an association between age-related disease, neurodegeneration, and racemization originated from the studies of fossils and cataract disease. Under the pressure of new results, this concept has a broader significance linking protein folding, aggregation, and disfunction to an organism's cognitive and behavioral functions. The integrity of cognitive function is provided by a delicate balance between the evolutionarily imposed molecular homo-chirality and the epigenetic/developmental impact of spontaneous and enzymatic racemization. The chirality of amino acids is the crucial player in the modulation the structure and function of proteins, lipids, and DNA. The collapse of homochirality by racemization is the result of the conformational phase transition. The racemization of protein-bound amino acids (spontaneous and enzymatic) occurs through thermal activation over the energy barrier or by the tunnel transfer effect under the energy barrier. The phase transition is achieved through the intermediate state, where the chirality of alpha carbon vanished. From a thermodynamic consideration, the system in the homo-chiral (single enantiomeric) state is characterized by a decreased level of entropy. The oscillating protein chirality is suggesting its distinct significance in the neurotransmission and flow of perceptual information, adaptive associative learning, and cognitive laterality. The common pathological hallmarks of neurodegenerative disorders include protein misfolding, aging, and the deposition of protease-resistant protein aggregates. Each of the landmarks is influenced by racemization. The brain region, cell type, and age-dependent racemization critically influence the functions of many intracellular, membrane-bound, and extracellular proteins including amyloid precursor protein (APP), TAU, PrP, Huntingtin, α-synuclein, myelin basic protein (MBP), and collagen. The amyloid cascade hypothesis in Alzheimer's disease (AD) coexists with the failure of amyloid beta (Aβ) targeting drug therapy. According to our view, racemization should be considered as a critical factor of protein conformation with the potential for inducing order, disorder, misfolding, aggregation, toxicity, and malfunctions.
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Affiliation(s)
- Victor V. Dyakin
- Virtual Reality Perception Lab (VRPL), The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
| | - Thomas M. Wisniewski
- Departments of Neurology, Pathology and Psychiatry, Center for Cognitive Neurology, New York University School of Medicine, New York, NY 10016, USA
| | - Abel Lajtha
- Center for Neurochemistry, The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
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Simultaneous Measurement of Amino Acid Enantiomers in Aged Mouse Brain Samples by LC/MS/MS Combined with Derivatization Using N
α-(5-Fluoro-2,4-dinitrophenyl)-l-leucinamide (l-FDLA). Metabolites 2021; 11:metabo11010057. [PMID: 33467775 PMCID: PMC7829926 DOI: 10.3390/metabo11010057] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/12/2022] Open
Abstract
d-amino acids have distinct roles from their l-enantiomer. In particular, some d-amino acids function as agonists or antagonists of neuronal receptors and are involved in higher brain functions. Thus, it is important to precisely measure the levels of these amino acid enantiomers in cells and tissues. Various quantification methods have been developed for measurements of chiral amino acids. However, each method has advantages and disadvantages. Additionally, measuring the amino acid enantiomers in crude biological samples requires a higher selectivity. In this study, we developed a quantification method for amino acid enantiomers using derivatization with Nα-(5-Fluoro-2,4-dinitrophenyl)-l-leucinamide (l-FDLA) followed by liquid chromatography–tandem mass spectrometry (LC/MS/MS) with a conventional reversed-phase column. We simultaneously identified 10 chiral amino acids. Furthermore, we applied this method to investigate murine tissue samples and examined the effect of aging on the amino acid levels in aged brain regions. We found that aging decreased the levels of both d-serine and d-aspartate in the hippocampus. In addition, d-Phenylalanine in the thalamus significantly increased with age. In conclusion, our method is suitable for the quantification of the d-amino acids in crude biological samples and may contribute to elucidating the biological roles of chiral amino acids.
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13
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Orzylowski M, Fujiwara E, Mousseau DD, Baker GB. An Overview of the Involvement of D-Serine in Cognitive Impairment in Normal Aging and Dementia. Front Psychiatry 2021; 12:754032. [PMID: 34707525 PMCID: PMC8542907 DOI: 10.3389/fpsyt.2021.754032] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/02/2021] [Indexed: 12/14/2022] Open
Abstract
Dementia, of which Alzheimer's disease (AD) is the most common form, is characterized by progressive cognitive deterioration, including profound memory loss, which affects functioning in many aspects of life. Although cognitive deterioration is relatively common in aging and aging is a risk factor for AD, the condition is not necessarily a part of the aging process. The N-methyl-D-aspartate glutamate receptor (NMDAR) and its co-agonist D-serine are currently of great interest as potential important contributors to cognitive function in normal aging and dementia. D-Serine is necessary for activation of the NMDAR and in maintenance of long-term potentiation (LTP) and is involved in brain development, neuronal connectivity, synaptic plasticity and regulation of learning and memory. In this paper, we review evidence, from both preclinical and human studies, on the involvement of D-serine (and the enzymes involved in its metabolism) in regulation of cognition. Potential mechanisms of action of D-serine are discussed in the context of normal aging and in dementia, as is the potential for using D-serine as a potential biomarker and/or therapeutic agent in dementia. Although there is some controversy in the literature, it has been proposed that in normal aging there is decreased expression of serine racemase and decreased levels of D-serine and down-regulation of NMDARs, resulting in impaired synaptic plasticity and deficits in learning and memory. In contrast, in AD there appears to be activation of serine racemase, increased levels of D-serine and overstimulation of NMDARs, resulting in cytotoxicity, synaptic deficits, and dementia.
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Affiliation(s)
- Magdalena Orzylowski
- Villa Caritas Geriatric Psychiatry Hospital, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Esther Fujiwara
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Darrell D Mousseau
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Glen B Baker
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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14
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Nagy LV, Bali ZK, Kapus G, Pelsőczi P, Farkas B, Lendvai B, Lévay G, Hernádi I. Converging Evidence on D-Amino Acid Oxidase-Dependent Enhancement of Hippocampal Firing Activity and Passive Avoidance Learning in Rats. Int J Neuropsychopharmacol 2020; 24:434-445. [PMID: 33305805 PMCID: PMC8130201 DOI: 10.1093/ijnp/pyaa095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND N-methyl-D-aspartate (NMDA) receptor activation requires the binding of a co-agonist on the glycine-binding site. D-serine is the main endogenous co-agonist of NMDA receptors, and its availability significantly depends on the activity of the metabolic enzyme D-amino acid oxidase (DAAO). Inhibition of DAAO increases the brain levels of D-serine and modulates a variety of physiological functions, including cognitive behavior. METHODS Here, we examined the effects of a novel 4-hydroxypyridazin-3(2H)-one derivative DAAO inhibitor, Compound 30 (CPD30), on passive avoidance learning and on neuronal firing activity in rats. RESULTS D-serine administration was applied as reference, which increased cognitive performance and enhanced hippocampal firing activity and responsiveness to NMDA after both local and systemic application. Similarly to D-serine, CPD30 (0.1 mg/kg) effectively reversed MK-801-induced memory impairment in the passive avoidance test. Furthermore, local iontophoretic application of CPD30 in the vicinity of hippocampal pyramidal neurons significantly increased firing rate and enhanced their responses to locally applied NMDA. CPD30 also enhanced hippocampal firing activity after systemic administration. In 0.1- to 1.0-mg/kg doses, CPD30 increased spontaneous and NMDA-evoked firing activity of the neurons. Effects of CPD30 on NMDA responsiveness emerged faster (at 10 minutes post-injection) when a 1.0-mg/kg dose was applied compared with the onset of the effects of 0.1 mg/kg CPD30 (at 30 minutes post-injection). CONCLUSIONS The present results confirm that the inhibition of DAAO enzyme is an effective strategy for cognitive enhancement. Our findings further facilitate the understanding of the cellular mechanisms underlying the behavioral effects of DAAO inhibition in the mammalian brain.
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Affiliation(s)
- Lili Veronika Nagy
- Department of Experimental Zoology and Neurobiology, Faculty of Sciences, University of Pécs, Pécs, Hungary,Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Zsolt Kristóf Bali
- Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary,Grastyán Translational Research Center, University of Pécs, Pécs, Hungary,Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary,Correspondence: Zsolt Kristóf Bali, PhD, Translational Neuroscience Research Group, Grastyán Translational Research Center, 6 Ifjúság út, H-7624, Pécs, Hungary ()
| | - Gábor Kapus
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Péter Pelsőczi
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Bence Farkas
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Balázs Lendvai
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - György Lévay
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary,Department of Morphology and Physiology, Faculty of Health Sciences, Semmelweis University, Budapest, Hungary
| | - István Hernádi
- Department of Experimental Zoology and Neurobiology, Faculty of Sciences, University of Pécs, Pécs, Hungary,Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary,Grastyán Translational Research Center, University of Pécs, Pécs, Hungary,Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
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15
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Wu Q, Chen X, Li J, Sun S. Serine and Metabolism Regulation: A Novel Mechanism in Antitumor Immunity and Senescence. Aging Dis 2020; 11:1640-1653. [PMID: 33269112 PMCID: PMC7673844 DOI: 10.14336/ad.2020.0314] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/14/2020] [Indexed: 12/16/2022] Open
Abstract
As one of the nonessential amino acids (NEAAs), serine is involved in the anabolism of multiple macromolecular substances by participating in one-carbon unit metabolism. Thus, rapidly proliferating cells such as tumor cells and activated immune cells are highly dependent on serine. Serine supports the proliferation of various immune cells through multiple pathways to enhance the antitumor immune response. Moreover, serine influences aging specificity in an epigenetic and metabolic manner. In this review, we focus on recent advances in the relationship between serine metabolism, antitumor immunity, and senescence. The metabolic regulation of serine seems to be a key point of intervention in antitumor immunity and aging-related disease, providing an opportunity for several novel therapeutics.
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Affiliation(s)
- Qi Wu
- 1Department of Breast and Thyroid Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Xinyue Chen
- 1Department of Breast and Thyroid Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Juanjuan Li
- 1Department of Breast and Thyroid Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Shengrong Sun
- 1Department of Breast and Thyroid Surgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
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16
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Ploux E, Freret T, Billard JM. d-serine in physiological and pathological brain aging. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140542. [PMID: 32950692 DOI: 10.1016/j.bbapap.2020.140542] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/10/2020] [Accepted: 09/13/2020] [Indexed: 01/24/2023]
Abstract
Among aging-induced impairments, those affecting cognitive functions certainly represent one the most major challenge to face to improve elderly quality of life. In last decades, our knowledge on changes in the morphology and function of neuronal networks associated with normal and pathological brain aging has rapidly progressed, initiating the development of different pharmacological and behavioural strategies to alleviate cognitive aging. In particular, experimental evidences have accumulated indicating that the communication between neurons and its plasticity gradually weakens with aging. Because of its pivotal role for brain functional plasticity, the N-Methyl‑d-Aspartate receptor subtype of glutamate receptors (NMDAr) has gathered much of the experimental interest. NMDAr activation is regulated by many mechanisms. Among is the mandatory binding of a co-agonist, such as the amino acid d-serine, in order to activate NMDAr. This mini-review presents the most recent information indicating how d-serine could contribute to mechanisms of physiological cognitive aging and also considers the divergent views relative of the role of the NMDAr co-agonist in Alzheimer's disease.
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Affiliation(s)
- E Ploux
- Normandie Univ, UNICAEN, INSERM, CYCERON, COMETE, 14000 Caen, France.
| | - T Freret
- Normandie Univ, UNICAEN, INSERM, CYCERON, COMETE, 14000 Caen, France
| | - J-M Billard
- Normandie Univ, UNICAEN, INSERM, CYCERON, COMETE, 14000 Caen, France.
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17
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Lakatos PP, Vincze I, Nyariki N, Bagaméry F, Tábi T, Szökő É. The effect of L-theanine and S-ketamine on d-serine cellular uptake. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140473. [PMID: 32574765 DOI: 10.1016/j.bbapap.2020.140473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/12/2020] [Accepted: 06/13/2020] [Indexed: 11/30/2022]
Abstract
Decreased extracellular level of d-Serine (D-Ser), a co-agonist of the N-methyl-d-aspartate (NMDA) receptors was connected to receptor hypofunction in the brain and the related deficit of cognitive functions. Extracellular D-Ser concentration is modulated by ASCT neutral amino acid transporters. L-Theanine (L-Tea), a neutral amino acid component of green tea was reported to improve cognitive functions. We thus intended to investigate the possible inhibitory effect of L-Tea on the D-Ser uptake of SH-SY5Y neuroblastoma cells, which was previously found as a good model of D-Ser transport into astrocytes. Cells were incubated with D-Ser and various concentrations of L-Tea or the reference compound S-ketamine (S-Ket). The effect on the uptake was assessed by measuring the intracellular D-Ser concentration using a capillary electrophoresis - laser induced fluorescence detection method. L-Tea competitively inhibited D-Ser uptake into SH-SY5Y cells with an IC50 value of 9.68 mM. Having previously described as an inhibitor of ASCT-2 transporter, S-Ket was intended to be used as a positive control. However, no acute inhibition of D-Ser transport by S-Ket was observed. Its long-term effect on the transport was also examined. No significant difference in D-Ser uptake in control and S-Ket-treated cells was found after 72 h treatment, although the intracellular D-Ser content of the 50 μM S-Ket pre-treated cells was significantly higher. L-Tea was found to be a weak competitive inhibitor of the ASCT transporters, while S-Ket did not directly affect D-Ser uptake or modify the uptake kinetics after a long-term incubation period.
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Affiliation(s)
- Péter P Lakatos
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
| | - István Vincze
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
| | - Noel Nyariki
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
| | - Fruzsina Bagaméry
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
| | - Tamás Tábi
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
| | - Éva Szökő
- Department of Pharmacodynamics, Semmelweis University, 4 Nagyvárad tér, Budapest H-1089, Hungary.
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18
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The Disease-Associated Chaperone FKBP51 Impairs Cognitive Function by Accelerating AMPA Receptor Recycling. eNeuro 2019; 6:eN-NWR-0242-18. [PMID: 30963102 PMCID: PMC6450497 DOI: 10.1523/eneuro.0242-18.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 01/18/2019] [Accepted: 02/01/2019] [Indexed: 12/22/2022] Open
Abstract
Increased expression of the FK506-binding protein 5 (FKBP5) gene has been associated with a number of diseases, but most prominently in connection to psychiatric illnesses. Many of these psychiatric disorders present with dementia and other cognitive deficits, but a direct connection between these issues and alterations in FKBP5 remains unclear. We generated a novel transgenic mouse to selectively overexpress FKBP5, which encodes the FKBP51 protein, in the corticolimbic system, which had no overt effects on gross body weight, motor ability, or general anxiety. Instead, we found that overexpression of FKBP51 impaired long-term depression (LTD) as well as spatial reversal learning and memory, suggesting a role in glutamate receptor regulation. Indeed, FKBP51 altered the association of heat-shock protein 90 (Hsp90) with AMPA receptors, which was accompanied by an accelerated rate of AMPA recycling. In this way, the chaperone system is critical in triage decisions for AMPA receptor trafficking. Imbalance in the chaperone system may manifest in impairments in both inhibitory learning and cognitive function. These findings uncover an unexpected and essential mechanism for learning and memory that is controlled by the psychiatric risk factor FKBP5.
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19
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Billard JM. Changes in Serine Racemase-Dependent Modulation of NMDA Receptor: Impact on Physiological and Pathological Brain Aging. Front Mol Biosci 2018; 5:106. [PMID: 30555832 PMCID: PMC6282039 DOI: 10.3389/fmolb.2018.00106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/09/2018] [Indexed: 02/02/2023] Open
Abstract
The N-methyl-D-Aspartate glutamate receptors (NMDARs) are pivotal for the functional and morphological plasticity that are required in neuronal networks for efficient brain activities and notably for cognitive-related abilities. Because NMDARs are heterogeneous in subunit composition and associated with multiple functional regulatory sites, their efficacy is under the tonic influence of numerous allosteric modulations, whose dysfunction generally represents the first step generating pathological states. Among the enzymatic candidates, serine racemase (SR) has recently gathered an increasing interest considering that it tightly regulates the production of d-serine, an amino acid now viewed as the main endogenous co-agonist necessary for NMDAR activation. Nowadays, SR deregulation is associated with a wide range of neurological and psychiatric diseases including schizophrenia, amyotrophic lateral sclerosis, and depression. This review aims at compelling the most recent experimental evidences indicating that changes in SR-related modulation of NMDARs also govern opposite functional dysfunctions in physiological and pathological (Alzheimer's disease) aging that finally results in memory disabilities in both cases. It also highlights SR as a relevant alternative target for new pharmacological strategies aimed at preventing functional alterations and cognitive impairments linked to the aging process.
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20
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Billard JM, Freret T. Asc-1 transporter activation: an alternative to rescue age-related alterations in functional plasticity at rat hippocampal CA3/CA1 synapses. J Neurochem 2018; 147:514-525. [DOI: 10.1111/jnc.14586] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/23/2018] [Accepted: 08/25/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Jean-Marie Billard
- Centre de Psychiatrie et Neurosciences; Université Paris Descartes; Sorbonne Paris Cité; UMR 894; Paris France
- Normandie Univ.; UNICAEN; INSERM; COMETE; Caen France
| | - Thomas Freret
- Normandie Univ.; UNICAEN; INSERM; COMETE; Caen France
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21
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Impact of Aging in Microglia-Mediated D-Serine Balance in the CNS. Mediators Inflamm 2018; 2018:7219732. [PMID: 30363571 PMCID: PMC6180939 DOI: 10.1155/2018/7219732] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 08/19/2018] [Accepted: 08/30/2018] [Indexed: 01/12/2023] Open
Abstract
A mild chronic inflammatory state, like that observed in aged individuals, affects microglial function, inducing a dysfunctional phenotype that potentiates neuroinflammation and cytotoxicity instead of neuroprotection in response to additional challenges. Given that inflammatory activation of microglia promotes increased release of D-serine, we postulate that age-dependent inflammatory brain environment leads to microglia-mediated changes on the D-serine-regulated glutamatergic transmission. Furthermore, D-serine dysregulation, in addition to affecting synaptogenesis and synaptic plasticity, appears also to potentiate NMDAR-dependent excitotoxicity, promoting neurodegeneration and cognitive impairment. D-serine dysregulation promoted by microglia could have a role in age-related cognitive impairment and in the induction and progression of neurodegenerative processes like Alzheimer's disease.
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22
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Altered function of neuronal L-type calcium channels in ageing and neuroinflammation: Implications in age-related synaptic dysfunction and cognitive decline. Ageing Res Rev 2018; 42:86-99. [PMID: 29339150 DOI: 10.1016/j.arr.2018.01.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/10/2018] [Accepted: 01/11/2018] [Indexed: 12/29/2022]
Abstract
The rapid developments in science have led to an increase in human life expectancy and thus, ageing and age-related disorders/diseases have become one of the greatest concerns in the 21st century. Cognitive abilities tend to decline as we get older. This age-related cognitive decline is mainly attributed to aberrant changes in synaptic plasticity and neuronal connections. Recent studies show that alterations in Ca2+ homeostasis underlie the increased vulnerability of neurons to age-related processes like cognitive decline and synaptic dysfunctions. Dysregulation of Ca2+ can lead to dramatic changes in neuronal functions. We discuss in this review, the recent advances on the potential role of dysregulated Ca2+ homeostasis through altered function of L-type voltage gated Ca2+ channels (LTCC) in ageing, with an emphasis on cognitive decline. This review therefore focuses on age-related changes mainly in the hippocampus, and with mention of other brain areas, that are important for learning and memory. This review also highlights age-related memory deficits via synaptic alterations and neuroinflammation. An understanding of these mechanisms will help us formulate strategies to reverse or ameliorate age-related disorders like cognitive decline.
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23
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Guercio GD, Panizzutti R. Potential and Challenges for the Clinical Use of d-Serine As a Cognitive Enhancer. Front Psychiatry 2018; 9:14. [PMID: 29459833 PMCID: PMC5807334 DOI: 10.3389/fpsyt.2018.00014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/17/2018] [Indexed: 12/16/2022] Open
Abstract
After 25 years of its discovery in the rat brain, d-serine is a recognized modulator of synaptic plasticity and cognitive processes through its actions on the NMDA-glutamate receptor. Importantly, cognitive impairment is a core feature of conditions, such as schizophrenia, Alzheimer's disease, depression, and aging, and is associated to disturbances in NMDA-glutamate receptors. The d-serine pathway has been associated with cognitive deficits and these conditions, and, for this reason, d-serine signaling is subject of intense research to probe its role in aiding diagnosis and therapy. Nevertheless, this has not resulted in new therapies being incorporated into clinical practice. Therefore, in this review we will address many questions that need to be solved by future studies, regarding d-serine pharmacokinetics, possible side effects, other strategies to modulate its levels, and combination with other therapies to increase its efficacy.
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Affiliation(s)
- Gerson D. Guercio
- Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rogerio Panizzutti
- Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland
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24
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Avellar M, Scoriels L, Madeira C, Vargas-Lopes C, Marques P, Dantas C, Manhães AC, Leite H, Panizzutti R. The effect of D-serine administration on cognition and mood in older adults. Oncotarget 2017; 7:11881-8. [PMID: 26933803 PMCID: PMC4914255 DOI: 10.18632/oncotarget.7691] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/30/2016] [Indexed: 11/25/2022] Open
Abstract
Background D-serine is an endogenous co-agonist of the N-Methyl D-Aspartate Receptor (NMDAR) that plays a crucial role in cognition including learning processes and memory. Decreased D-serine levels have been associated with age-related decline in mechanisms of learning and memory in animal studies. Here, we asked whether D-serine administration in older adults improves cognition. Results D-serine administration improved performance in the Groton Maze learning test of spatial memory and learning and problem solving (F(3, 38)= 4.74, p = 0.03). Subjects that achieved higher increases in plasma D-serine levels after administration improved more in test performance (r2=−0.19 p = 0.009). D-serine administration was not associated with any significant changes in the other cognitive tests or in the mood of older adults (p > 0.05). Methods Fifty healthy older adults received D-serine and placebo in a randomized, double blind, placebo-controlled, crossover design study. We studied the effect of D-serine administration on the performance of cognitive tests and an analogue mood scale. We also collected blood samples to measure D-serine, L-serine, glutamate and glutamine levels. Conclusions D-serine administration may be a strategy to improve spatial memory, learning and problem solving in healthy older adults. Future studies should evaluate the impact of long-term D-serine administration on cognition in older adults.
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Affiliation(s)
- Marcos Avellar
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil.,Institute of Psychiatry, Federal University of Rio de Janeiro, RJ, Brazil
| | - Linda Scoriels
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil.,Institute of Psychiatry, Federal University of Rio de Janeiro, RJ, Brazil.,Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
| | - Caroline Madeira
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | | | - Priscila Marques
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | - Camila Dantas
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | - Alex C Manhães
- Institute of Biology Roberto Alcantara Gomes, Biomedical Center, State University of Rio de Janeiro, RJ, Brazil
| | - Homero Leite
- Integrated Unit for Prevention, Adventist Silvestre Hospital, Rio de Janeiro, RJ, Brazil
| | - Rogerio Panizzutti
- Biomedical Sciences Institute, Federal University of Rio de Janeiro, RJ, Brazil.,Institute of Psychiatry, Federal University of Rio de Janeiro, RJ, Brazil
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25
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Foster AC, Farnsworth J, Lind GE, Li YX, Yang JY, Dang V, Penjwini M, Viswanath V, Staubli U, Kavanaugh MP. D-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures. PLoS One 2016; 11:e0156551. [PMID: 27272177 PMCID: PMC4896441 DOI: 10.1371/journal.pone.0156551] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/16/2016] [Indexed: 11/18/2022] Open
Abstract
N-methyl-D-aspartate (NMDA) receptors play critical roles in synaptic transmission and plasticity. Activation of NMDA receptors by synaptically released L-glutamate also requires occupancy of co-agonist binding sites in the tetrameric receptor by either glycine or D-serine. Although D-serine appears to be the predominant co-agonist at synaptic NMDA receptors, the transport mechanisms involved in D-serine homeostasis in brain are poorly understood. In this work we show that the SLC1 amino acid transporter family members SLC1A4 (ASCT1) and SLC1A5 (ASCT2) mediate homo- and hetero-exchange of D-serine with physiologically relevant kinetic parameters. In addition, the selectivity profile of D-serine uptake in cultured rat hippocampal astrocytes is consistent with uptake mediated by both ASCT1 and ASCT2. Together these data suggest that SLC1A4 (ASCT1) may represent an important route of Na-dependent D-serine flux in the brain that has the ability to regulate extracellular D-serine and thereby NMDA receptor activity.
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Affiliation(s)
- Alan C. Foster
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
- * E-mail: (YXL); (ACF); (MPK)
| | - Jill Farnsworth
- Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT 59812, United States of America
| | - Genevieve E. Lind
- Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT 59812, United States of America
| | - Yong-Xin Li
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
- * E-mail: (YXL); (ACF); (MPK)
| | - Jia-Ying Yang
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
| | - Van Dang
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
| | - Mahmud Penjwini
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
| | - Veena Viswanath
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
| | - Ursula Staubli
- Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, United States of America
| | - Michael P. Kavanaugh
- Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT 59812, United States of America
- * E-mail: (YXL); (ACF); (MPK)
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Taurine content in different brain structures during ageing: effect on hippocampal synaptic plasticity. Amino Acids 2016; 48:1199-208. [DOI: 10.1007/s00726-015-2155-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/10/2015] [Indexed: 10/22/2022]
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Currais A, Goldberg J, Farrokhi C, Chang M, Prior M, Dargusch R, Daugherty D, Armando A, Quehenberger O, Maher P, Schubert D. A comprehensive multiomics approach toward understanding the relationship between aging and dementia. Aging (Albany NY) 2015; 7:937-55. [PMID: 26564964 PMCID: PMC4694064 DOI: 10.18632/aging.100838] [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: 09/15/2015] [Accepted: 10/30/2015] [Indexed: 04/14/2023]
Abstract
Because age is the greatest risk factor for sporadic Alzheimer's disease (AD), phenotypic screens based upon old age-associated brain toxicities were used to develop the potent neurotrophic drug J147. Since certain aspects of aging may be primary cause of AD, we hypothesized that J147 would be effective against AD-associated pathology in rapidly aging SAMP8 mice and could be used to identify some of the molecular contributions of aging to AD. An inclusive and integrative multiomics approach was used to investigate protein and gene expression, metabolite levels, and cognition in old and young SAMP8 mice. J147 reduced cognitive deficits in old SAMP8 mice, while restoring multiple molecular markers associated with human AD, vascular pathology, impaired synaptic function, and inflammation to those approaching the young phenotype. The extensive assays used in this study identified a subset of molecular changes associated with aging that may be necessary for the development of AD.
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Affiliation(s)
- Antonio Currais
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Joshua Goldberg
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | | | - Max Chang
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Marguerite Prior
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Richard Dargusch
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Daniel Daugherty
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Aaron Armando
- Department of Medicine, University of California San Diego, CA 92093-0601, USA
| | - Oswald Quehenberger
- Department of Medicine, University of California San Diego, CA 92093-0601, USA
| | - Pamela Maher
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - David Schubert
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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Mothet JP, Le Bail M, Billard JM. Time and space profiling of NMDA receptor co-agonist functions. J Neurochem 2015; 135:210-25. [DOI: 10.1111/jnc.13204] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/12/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Affiliation(s)
- Jean-Pierre Mothet
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Matildé Le Bail
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Jean-Marie Billard
- Center of Psychiatry and Neuroscience; University Paris Descartes; Sorbonne Paris City; UMR 894; Paris France
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29
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Billard JM. D-Serine in the aging hippocampus. J Pharm Biomed Anal 2015; 116:18-24. [PMID: 25740810 DOI: 10.1016/j.jpba.2015.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 02/03/2015] [Accepted: 02/07/2015] [Indexed: 01/06/2023]
Abstract
Experimental evidences now indicate that memory formation relies on the capacity of neuronal networks to manage long-term changes in synaptic communication. This property is driven by N-methyl-D-aspartate receptors (NMDAR), which requires the binding of glutamate but also the presence of the co-agonist D-serine at the glycine site. Defective memory function and impaired brain synaptic plasticity observed in aging are rescued by partial agonist acting at this site suggesting that this gating process is targeted to induce age-related cognitive defects. This review aims at compelling recent studies characterizing the role of D-serine in changes in functional plasticity that occur in the aging hippocampus since deficits are rescued by D-serine supplementation. The impaired efficacy of endogenous D-serine is not due to changes in the affinity to glycine-binding site but to a decrease in tissue levels of the amino acid resulting from a weaker expression of the producing enzyme serine racemase (SR). Interestingly, neither SR expression, D-serine levels, nor NMDAR activation is affected in aged LOU/C rats, a model of healthy aging in which memory deficits do not occur. These old animals do not develop oxidative stress suggesting that the D-serine-related pathway could be targeted by the age-related accumulation of reactive oxygen species. Accordingly, senescent rats chronically treated with the reducing agent N-acetyl-cysteine to prevent oxidative damage, show intact NMDAR activation linked to preserved D-serine levels and SR expression. These results point to a significant role of D-serine in age-related functional alterations underlying hippocampus-dependent memory deficits, at least within the CA1 area since the amino acid does not appear as critical in changes affecting the dentate gyrus.
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Affiliation(s)
- Jean-Marie Billard
- Center of Psychiatry and Neurosciences, Paris Descartes University, Sorbonne Paris City, UMR U894, Paris 75014 France.
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30
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Ménard C, Gaudreau P, Quirion R. Signaling pathways relevant to cognition-enhancing drug targets. Handb Exp Pharmacol 2015; 228:59-98. [PMID: 25977080 DOI: 10.1007/978-3-319-16522-6_3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aging is generally associated with a certain cognitive decline. However, individual differences exist. While age-related memory deficits can be observed in humans and rodents in the absence of pathological conditions, some individuals maintain intact cognitive functions up to an advanced age. The mechanisms underlying learning and memory processes involve the recruitment of multiple signaling pathways and gene expression, leading to adaptative neuronal plasticity and long-lasting changes in brain circuitry. This chapter summarizes the current understanding of how these signaling cascades could be modulated by cognition-enhancing agents favoring memory formation and successful aging. It focuses on data obtained in rodents, particularly in the rat as it is the most common animal model studied in this field. First, we will discuss the role of the excitatory neurotransmitter glutamate and its receptors, downstream signaling effectors [e.g., calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C (PKC), extracellular signal-regulated kinases (ERK), mammalian target of rapamycin (mTOR), cAMP response element-binding protein (CREB)], associated immediate early gene (e.g., Homer 1a, Arc and Zif268), and growth factors [insulin-like growth factors (IGFs) and brain-derived neurotrophic factor (BDNF)] in synaptic plasticity and memory formation. Second, the impact of the cholinergic system and related modulators on memory will be briefly reviewed. Finally, since dynorphin neuropeptides have recently been associated with memory impairments in aging, it is proposed as an attractive target to develop novel cognition-enhancing agents.
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Affiliation(s)
- Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Perry Pavilion, 6875 LaSalle Boulevard, Montreal, QC, Canada, H4H 1R3
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Identity of the NMDA receptor coagonist is synapse specific and developmentally regulated in the hippocampus. Proc Natl Acad Sci U S A 2014; 112:E204-13. [PMID: 25550512 DOI: 10.1073/pnas.1416668112] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
NMDA receptors (NMDARs) require the coagonists D-serine or glycine for their activation, but whether the identity of the coagonist could be synapse specific and developmentally regulated remains elusive. We therefore investigated the contribution of D-serine and glycine by recording NMDAR-mediated responses at hippocampal Schaffer collaterals (SC)-CA1 and medial perforant path-dentate gyrus (mPP-DG) synapses in juvenile and adult rats. Selective depletion of endogenous coagonists with enzymatic scavengers as well as pharmacological inhibition of endogenous D-amino acid oxidase activity revealed that D-serine is the preferred coagonist at SC-CA1 mature synapses, whereas, unexpectedly, glycine is mainly involved at mPP-DG synapses. Nevertheless, both coagonist functions are driven by the levels of synaptic activity as inferred by recording long-term potentiation generated at both connections. This regional compartmentalization in the coagonist identity is associated to different GluN1/GluN2A to GluN1/GluN2B subunit composition of synaptic NMDARs. During postnatal development, the replacement of GluN2B- by GluN2A-containing NMDARs at SC-CA1 synapses parallels a change in the identity of the coagonist from glycine to D-serine. In contrast, NMDARs subunit composition at mPP-DG synapses is not altered and glycine remains the main coagonist throughout postnatal development. Altogether, our observations disclose an unprecedented relationship in the identity of the coagonist not only with the GluN2 subunit composition at synaptic NMDARs but also with astrocyte activity in the developing and mature hippocampus that reconciles the complementary functions of D-serine And Glycine In Modulating Nmdars During The Maturation Of Tripartite Glutamatergic Synapses.
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32
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VanSwearingen JM, Studenski SA. Aging, motor skill, and the energy cost of walking: implications for the prevention and treatment of mobility decline in older persons. J Gerontol A Biol Sci Med Sci 2014; 69:1429-36. [PMID: 25182600 PMCID: PMC4271095 DOI: 10.1093/gerona/glu153] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 07/29/2014] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Age-associated neural changes profoundly affect the biomechanics and energetics of walking, increase energy cost, and require novel approaches to exercise that focus on motor learning theory. METHODS We present a conceptual framework for motor skill in walking, its effect on the energy cost of walking, and the influence of the aging brain. RESULTS Motor learning theory and practice can be incorporated into interventions to promote skilled, energy efficient walking in older people. CONCLUSIONS An extensive literature on motor skill and motor learning, derived from neuroscience, sports medicine, and neurorehabilitation, can be applied to problems of walking in late life.
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33
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Labarrière M, Thomas F, Dutar P, Pollegioni L, Wolosker H, Billard JM. Circuit-specific changes in D-serine-dependent activation of the N-methyl-D-aspartate receptor in the aging hippocampus. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9698. [PMID: 25138794 PMCID: PMC4453931 DOI: 10.1007/s11357-014-9698-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 07/27/2014] [Indexed: 05/29/2023]
Abstract
Age-related memory deficits have recently been associated with the impaired expression of D-serine-dependent synaptic plasticity in neuronal networks of the hippocampal CA1 area. However, whether such functional alterations are common to the entire hippocampus during aging remains unknown. Here, we found that D-serine was also required for the induction of N-methyl-D-aspartate receptor (NMDA-R)-dependent long-term potentiation (LTP) at perforant path-granule cell synapses of the dentate gyrus. LTP as well as isolated NMDA-R synaptic potentials were impaired in slices from aged rats, but in contrast to the CA1, this defect was not reversed by exogenous D-serine. The lower activation of the glycine-binding site by the endogenous co-agonist does not therefore appear to be a critical mechanism underlying age-related deficits in NMDA-R activation in the dentate gyrus. Instead, our data highlight the role of changes in presynaptic inputs as illustrated by the weaker responsiveness of afferent glutamatergic fibers, as well as changes in postsynaptic NMDA-R density. Thus, our study indicates that although NMDA-R-dependent mechanisms driving synaptic plasticity are quite similar between hippocampal circuits, they show regional differences in their susceptibility to aging, which could hamper the development of effective therapeutic strategies aimed at reducing cognitive aging.
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Affiliation(s)
- M. Labarrière
- />Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014 France
| | - F. Thomas
- />Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014 France
| | - P. Dutar
- />Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014 France
| | - L. Pollegioni
- />Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell’Insubria, via J.H. Dunant 3, 21100 Varese, Italy
- />The Protein Factory, Centro Interuniversitario di Biotecnologie Proteiche, Politecnico di Milano, ICRM CNR Milano, and Università degli Studi dell’Insubria, via Mancinelli 7, 20137 Milano, Italy
| | - H. Wolosker
- />Department of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31036 Israel
| | - J.-M. Billard
- />Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014 France
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34
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D'Ascenzo M, Podda MV, Grassi C. The role of D-serine as co-agonist of NMDA receptors in the nucleus accumbens: relevance to cocaine addiction. Front Synaptic Neurosci 2014; 6:16. [PMID: 25076900 PMCID: PMC4100571 DOI: 10.3389/fnsyn.2014.00016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/29/2014] [Indexed: 12/20/2022] Open
Abstract
Cocaine addiction is characterized by compulsive drug use despite adverse consequences and high rate of relapse during periods of abstinence. Increasing consensus suggests that addiction to drugs of abuse usurps learning and memory mechanisms normally related to natural rewards, ultimately producing long-lasting neuroadaptations in the mesocorticolimbic system. This system, formed in part by the ventral tegmental area and nucleus accumbens (NAc), has a central role in the development and expression of addictive behaviors. In addition to a broad spectrum of changes that affect morphology and function of NAc excitatory circuits in cocaine–treated animals, impaired N-methyl-D-aspartate receptor (NMDAR)-dependent synaptic plasticity is a typical feature. D-serine, a D-amino acid that has been found at high levels in mammalian brain, binds with high affinity the co-agonist site of NMDAR and mediates, along with glutamate, several important processes including synaptic plasticity. Here we review recent literature focusing on cocaine-induced impairment in synaptic plasticity mechanisms in the NAc and on the fundamental role of D-serine as co-agonist of NMDAR in functional and dysfunctional synaptic plasticity within this nucleus. The emerging picture is that reduced D-serine levels play a crucial role in synaptic plasticity relevant to cocaine addiction. This finding opens new perspectives for therapeutic approaches to treat this addictive state.
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Affiliation(s)
- Marcello D'Ascenzo
- Institute of Human Physiology, Medical School, Universitá Cattolica "S. Cuore" Rome, Italy
| | - Maria Vittoria Podda
- Institute of Human Physiology, Medical School, Universitá Cattolica "S. Cuore" Rome, Italy
| | - Claudio Grassi
- Institute of Human Physiology, Medical School, Universitá Cattolica "S. Cuore" Rome, Italy
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35
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López-Hidalgo M, Schummers J. Cortical maps: a role for astrocytes? Curr Opin Neurobiol 2014; 24:176-89. [DOI: 10.1016/j.conb.2013.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/31/2013] [Accepted: 11/01/2013] [Indexed: 12/21/2022]
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36
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Billard JM. Serine racemase as a prime target for age-related memory deficits. Eur J Neurosci 2013; 37:1931-8. [DOI: 10.1111/ejn.12226] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 02/26/2013] [Accepted: 03/22/2013] [Indexed: 11/29/2022]
Affiliation(s)
- J.-M. Billard
- Centre de Psychiatrie et Neurosciences; Faculté de Médecine; Université Paris Descartes; UMR 894; Sorbonne Paris Cité; 2 ter rue d'Alésia; Paris; 75014; France
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37
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Filali M, Lalonde R. The effects of subchronic d-serine on left–right discrimination learning, social interaction, and exploratory activity in APPswe/PS1 mice. Eur J Pharmacol 2013; 701:152-8. [DOI: 10.1016/j.ejphar.2012.12.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/12/2012] [Accepted: 12/19/2012] [Indexed: 10/27/2022]
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38
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Calcia MA, Madeira C, Alheira FV, Silva TCS, Tannos FM, Vargas-Lopes C, Goldenstein N, Brasil MA, Ferreira ST, Panizzutti R. Plasma levels of D-serine in Brazilian individuals with schizophrenia. Schizophr Res 2012; 142:83-7. [PMID: 23063707 DOI: 10.1016/j.schres.2012.09.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 09/08/2012] [Accepted: 09/17/2012] [Indexed: 01/08/2023]
Abstract
Changes in D-serine availability in the brain may contribute to the hypofunction of NMDA-glutamate receptors in schizophrenia; however, measurements of blood levels of D-serine in individuals with schizophrenia have not been consistent amongst previous studies. Here we studied plasma levels of D-serine and L-serine in 84 Brazilian individuals with schizophrenia and 75 gender- and age-matched controls. Plasma levels of D-serine and the ratio of plasma D-serine to total serine were significantly lower in individuals with schizophrenia as compared to the control group. Levels of D-serine were significantly and negatively correlated to the severity of negative symptoms of schizophrenia. We also observed that plasma levels of D-serine significantly decreased with aging in healthy controls. Our results suggest that the possible role of D-serine in the pathophysiology of schizophrenia should be further investigated, with possible implications for the drug treatment of this disorder.
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Affiliation(s)
- Marilia A Calcia
- Serviço de Psiquiatria e Psicologia Médica, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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39
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Scullin MK, Trotti LM, Wilson AG, Greer SA, Bliwise DL. Nocturnal sleep enhances working memory training in Parkinson's disease but not Lewy body dementia. Brain 2012; 135:2789-97. [PMID: 22907117 DOI: 10.1093/brain/aws192] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Working memory is essential to higher order cognition (e.g. fluid intelligence) and to performance of daily activities. Though working memory capacity was traditionally thought to be inflexible, recent studies report that working memory capacity can be trained and that offline processes occurring during sleep may facilitate improvements in working memory performance. We utilized a 48-h in-laboratory protocol consisting of repeated digit span forward (short-term attention measure) and digit span backward (working memory measure) tests and overnight polysomnography to investigate the specific sleep-dependent processes that may facilitate working memory performance improvements in the synucleinopathies. We found that digit span backward performance improved following a nocturnal sleep interval in patients with Parkinson's disease on dopaminergic medication, but not in those not taking dopaminergic medication and not in patients with dementia with Lewy bodies. Furthermore, the improvements in patients with Parkinson's disease on dopaminergic medication were positively correlated with the amount of slow-wave sleep that patients obtained between training sessions and negatively correlated with severity of nocturnal oxygen desaturation. The translational implication is that working memory capacity is potentially modifiable in patients with Parkinson's disease but that sleep disturbances may first need to be corrected.
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Affiliation(s)
- Michael K Scullin
- Department of Neurology, Program in Sleep Medicine, Emory University School of Medicine, 1841 Clifton Road, Room 506, Atlanta, GA 30329, USA.
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40
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Billard JM. d-Amino acids in brain neurotransmission and synaptic plasticity. Amino Acids 2012; 43:1851-60. [DOI: 10.1007/s00726-012-1346-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/16/2012] [Indexed: 01/25/2023]
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41
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New insights on the role of free D-aspartate in the mammalian brain. Amino Acids 2012; 43:1861-71. [PMID: 22851050 DOI: 10.1007/s00726-012-1356-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 06/27/2012] [Indexed: 12/23/2022]
Abstract
Free D-aspartate (D-Asp) occurs in substantial amounts in the brain at the embryonic phase and in the first few postnatal days, and strongly decreases in adulthood. Temporal reduction of D-Asp levels depends on the postnatal onset of D-aspartate oxidase (DDO) activity, the only enzyme able to selectively degrade this D-amino acid. Several results indicate that D-Asp binds and activates N-methyl-D-aspartate receptors (NMDARs). Accordingly, recent studies have demonstrated that deregulated, higher levels of D-Asp, in knockout mice for Ddo gene and in D-Asp-treated mice, modulate hippocampal NMDAR-dependent long-term potentiation (LTP) and spatial memory. Moreover, similarly to D-serine, administration of D-Asp to old mice is able to rescue the physiological age-related decay of hippocampal LTP. In agreement with a neuromodulatory action of D-Asp on NMDARs, increased levels of this D-amino acid completely suppress long-term depression at corticostriatal synapses and attenuate the prepulse inhibition deficits produced in mice by the psychotomimetic drugs, amphetamine and MK-801. Based on the evidence which points to the ability of D-Asp to act as an endogenous agonist on NMDARs and considering the abundance of D-Asp during prenatal and early life, future studies will be crucial to address the effect of this molecule in the developmental processes of the brain controlled by the activation of NMDARs.
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42
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Haxaire C, Turpin FR, Potier B, Kervern M, Sinet PM, Barbanel G, Mothet JP, Dutar P, Billard JM. Reversal of age-related oxidative stress prevents hippocampal synaptic plasticity deficits by protecting D-serine-dependent NMDA receptor activation. Aging Cell 2012; 11:336-44. [PMID: 22230264 DOI: 10.1111/j.1474-9726.2012.00792.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Oxidative stress (OS) resulting from an imbalance between antioxidant defenses and the intracellular accumulation of reactive oxygen species (ROS) contributes to age-related memory deficits. While impaired synaptic plasticity in neuronal networks is thought to underlie cognitive deficits during aging, whether this process is targeted by OS and what the mechanisms involved are still remain open questions. In this study, we investigated the age-related effects of the reducing agent N-acetyl-L-cysteine (L-NAC) on the activation of the N-methyl-D-aspartate receptor (NMDA-R) by its co-agonist D-serine, because alterations in this mechanism contribute greatly to synaptic plasticity deficits in aged animals. Long-term dietary supplementation with L-NAC prevented oxidative damage in the hippocampus of aged rats. Electrophysiological recordings in the CA1 of hippocampal slices indicated that NMDA-R-mediated synaptic potentials and theta-burst-induced long-term potentiation (LTP) were depressed in aged animals, deficits that could be reversed by exogenous D-serine. Chronic treatment with L-NAC, but not acute application of the reducing agent, restored potent D-serine-dependent NMDA-R activation and LTP induction in aged rats. In addition, it is also revealed that the age-related decrease in D-serine levels and in the expression of the synthesizing enzyme serine racemase, which underlies the decrease in NMDA-R activation by the amino acid, was rescued by long-term dietary treatment with L-NAC. Our results indicate that protecting redox status in aged animals could prevent injury to the cellular mechanisms underlying cognitive aging, in part by maintaining potent NMDA-R activation through the D-serine-dependent pathway.
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Affiliation(s)
- Coline Haxaire
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, France
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43
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Foster TC. Dissecting the age-related decline on spatial learning and memory tasks in rodent models: N-methyl-D-aspartate receptors and voltage-dependent Ca2+ channels in senescent synaptic plasticity. Prog Neurobiol 2012; 96:283-303. [PMID: 22307057 DOI: 10.1016/j.pneurobio.2012.01.007] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/09/2012] [Accepted: 01/19/2012] [Indexed: 10/14/2022]
Abstract
In humans, heterogeneity in the decline of hippocampal-dependent episodic memory is observed during aging. Rodents have been employed as models of age-related cognitive decline and the spatial water maze has been used to show variability in the emergence and extent of impaired hippocampal-dependent memory. Impairment in the consolidation of intermediate-term memory for rapidly acquired and flexible spatial information emerges early, in middle-age. As aging proceeds, deficits may broaden to include impaired incremental learning of a spatial reference memory. The extent and time course of impairment has been be linked to senescence of calcium (Ca²⁺) regulation and Ca²⁺-dependent synaptic plasticity mechanisms in region CA1. Specifically, aging is associated with altered function of N-methyl-D-aspartate receptors (NMDARs), voltage-dependent Ca²⁺ channels (VDCCs), and ryanodine receptors (RyRs) linked to intracellular Ca²⁺ stores (ICS). In young animals, NMDAR activation induces long-term potentiation of synaptic transmission (NMDAR-LTP), which is thought to mediate the rapid consolidation of intermediate-term memory. Oxidative stress, starting in middle-age, reduces NMDAR function. In addition, VDCCs and ICS can actively inhibit NMDAR-dependent LTP and oxidative stress enhances the role of VDCC and RyR-ICS in regulating synaptic plasticity. Blockade of L-type VDCCs promotes NMDAR-LTP and memory in older animals. Interestingly, pharmacological or genetic manipulations to reduce hippocampal NMDAR function readily impair memory consolidation or rapid learning, generally leaving incremental learning intact. Finally, evidence is mounting to indicate a role for VDCC-dependent synaptic plasticity in associative learning and the consolidation of remote memories. Thus, VDCC-dependent synaptic plasticity and extrahippocampal systems may contribute to incremental learning deficits observed with advanced aging.
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Affiliation(s)
- Thomas C Foster
- Department of Neuroscience, Evelyn F. and William L. McKnight Brain Institute, University of Florida, PO Box 100244, Gainesville, FL 32610-0244, USA. ,
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Chen Y, Fu AKY, Ip NY. Eph receptors at synapses: implications in neurodegenerative diseases. Cell Signal 2011; 24:606-11. [PMID: 22120527 DOI: 10.1016/j.cellsig.2011.11.016] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 11/05/2011] [Indexed: 12/16/2022]
Abstract
Precise regulation of synapse formation, maintenance and plasticity is crucial for normal cognitive function, and synaptic failure has been suggested as one of the hallmarks of neurodegenerative diseases. In this review, we describe the recent progress in our understanding of how the receptor tyrosine kinase Ephs and their ligands ephrins regulate dendritic spine morphogenesis, synapse formation and maturation, as well as synaptic plasticity. In particular, we discuss the emerging evidence implicating that deregulation of Eph/ephrin signaling contributes to the aberrant synaptic functions associated with cognitive impairment in Alzheimer's disease. Understanding how Eph/ephrin regulates synaptic function may therefore provide new insights into the development of therapeutic agents against neurodegenerative diseases.
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Affiliation(s)
- Yu Chen
- Divison of Life Science, State Key Laboratory of Molecular Neuroscience and Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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Yoon KD, Yamamoto K, Zhou J, Sparrow JR. Photo-products of retinal pigment epithelial bisretinoids react with cellular thiols. Mol Vis 2011; 17:1839-49. [PMID: 21850158 PMCID: PMC3137558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 07/05/2011] [Indexed: 10/30/2022] Open
Abstract
PURPOSE Bisretinoids such as A2E that accumulate as components of the lipofuscin of retinal pigment epithelial cells are implicated in some retinal disease processes. These compounds undergo light-induced oxidation and cleavage with the latter releasing of a mixture of aldehyde-bearing fragments, including dicarbonyl methylglyoxal. We tested for the reactivity of photooxidation and photodegradation products of A2E with thiol-containing glutathione (GSH). METHODS In cell-free assays, we measured the ability of photooxo-A2E to competitively inhibit the GSH-mediated reduction of the thiol reagent 5,5'-dithiobis-(2-nitrobenzoic acid). Cellular GSH was assayed colorimetrically. Products of GSH reduction and GSH-adducts were detected by electrospray ionization mass spectrometry (ESI-MS) and GSH and oxidized GSH (glutathione disulfide [GSSG]) were quantified from chromatographic peak areas. RESULTS We found that GSH can donate hydrogen atoms to, and form conjugates with, photooxidized forms of the bisretinoid A2E and with its photocleavage products. Reaction with non-photooxidized A2E was not observed. Chemical reduction by GSH involved the donation of a hydrogen atom from each of two GSHs. The ratio of GSH consumed to GSSG formed was consistent with GSH being used for both reduction and adduct formation. With the aid of synthesized standards, methylglyoxal-GSH adducts were identified within mixtures of GSH and photooxidized A2E; the adducts formed noncatalytically and by glutathione-S-transferase mediation. CONCLUSIONS Reduction and adduct formation by GSH likely limits the reactivity of bisretinoid photoproducts and may aid their elimination from the cells. These findings are significant to forms of macular degeneration associated with bisretinoid formation and maculopathy stemming from GSH synthase deficiency.
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Affiliation(s)
- Kee Dong Yoon
- Department of Ophthalmology, Columbia University, New York, NY
| | | | - Jilin Zhou
- Department of Ophthalmology, Columbia University, New York, NY
| | - Janet R. Sparrow
- Department of Ophthalmology, Columbia University, New York, NY,Department of Pathology and Cell Biology, Columbia University, New York, NY
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Labrie V, Wong AHC, Roder JC. Contributions of the D-serine pathway to schizophrenia. Neuropharmacology 2011; 62:1484-503. [PMID: 21295046 DOI: 10.1016/j.neuropharm.2011.01.030] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 01/16/2011] [Accepted: 01/19/2011] [Indexed: 01/30/2023]
Abstract
The glutamate neurotransmitter system is one of the major candidate pathways for the pathophysiology of schizophrenia, and increased understanding of the pharmacology, molecular biology and biochemistry of this system may lead to novel treatments. Glutamatergic hypofunction, particularly at the NMDA receptor, has been hypothesized to underlie many of the symptoms of schizophrenia, including psychosis, negative symptoms and cognitive impairment. This review will focus on D-serine, a co-agonist at the NMDA receptor that in combination with glutamate, is required for full activation of this ion channel receptor. Evidence implicating D-serine, NMDA receptors and related molecules, such as D-amino acid oxidase (DAO), G72 and serine racemase (SRR), in the etiology or pathophysiology of schizophrenia is discussed, including knowledge gained from mouse models with altered D-serine pathway genes and from preliminary clinical trials with D-serine itself or compounds modulating the D-serine pathway. Abnormalities in D-serine availability may underlie glutamatergic dysfunction in schizophrenia, and the development of new treatments acting through the D-serine pathway may significantly improve outcomes for many schizophrenia patients.
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Affiliation(s)
- Viviane Labrie
- Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada.
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Lynch AM, Murphy KJ, Deighan BF, O'Reilly JA, Gun'ko YK, Cowley TR, Gonzalez-Reyes RE, Lynch MA. The impact of glial activation in the aging brain. Aging Dis 2010; 1:262-278. [PMID: 22396865 PMCID: PMC3295033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/01/2010] [Accepted: 09/02/2010] [Indexed: 05/31/2023] Open
Abstract
The past decade or so has witnessed a rekindling of interest in glia requiring a re-evaluation of the early descriptions of astrocytes as merely support cells, and microglia as adopting either a resting state or an activated state in a binary fashion. We now know that both cell types contribute to the optimal functioning of neurons in the healthy brain, and that altered function of either cell impacts on neuronal function and consequently cognitive function. The evidence indicates that both astrocytic and microglial phenotype change with age and that the shift from the resting state is associated with deterioration in synaptic function. In this review, we consider the rapidly-expanding array of functions attributed to these cells and focus on evaluating the changes in cell activation that accompany ageing.
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Affiliation(s)
| | | | | | | | | | | | | | - Marina A. Lynch
- Correspondence should be addressed to: Dr. MA Lynch, Trinity College Institute of Neuroscience, Trinity College, Dublin 2, Ireland.
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DeVito LM, Balu DT, Kanter BR, Lykken C, Basu AC, Coyle JT, Eichenbaum H. Serine racemase deletion disrupts memory for order and alters cortical dendritic morphology. GENES BRAIN AND BEHAVIOR 2010; 10:210-22. [PMID: 21029376 DOI: 10.1111/j.1601-183x.2010.00656.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There is substantial evidence implicating N-methyl-D-aspartate receptors (NMDARs) in memory and cognition. It has also been suggested that NMDAR hypofunction might underlie the cognitive deficits observed in schizophrenia as morphological changes, including alterations in the dendritic architecture of pyramidal neurons in the prefrontal cortex (PFC), have been reported in the schizophrenic brain post mortem. Here, we used a genetic model of NMDAR hypofunction, a serine racemase knockout (SR-/-) mouse in which the first coding exon of the mouse SR gene has been deleted, to explore the role of D-serine in regulating cognitive functions as well as dendritic architecture. SR-/- mice exhibited a significantly disrupted representation of the order of events in distinct experiences as showed by object recognition and odor sequence tests; however, SR-/- animals were unimpaired in the detection of novel objects and in spatial displacement, and showed intact relational memory in a test of transitive inference. In addition, SR-/- mice exhibited normal sociability and preference for social novelty. Neurons in the medial PFC of SR-/- mice displayed reductions in the complexity, total length and spine density of apical dendrites. These findings show that D-serine is important for specific aspects of cognition, as well as in regulating dendritic morphology of pyramidal neurons in the medial PFC (mPFC). Moreover, they suggest that NMDAR hypofunction might, in part, be responsible for the cognitive deficits and synaptic changes associated with schizophrenia, and highlight this signaling pathway as a potential target for therapeutic intervention.
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Affiliation(s)
- L M DeVito
- Center for Memory and Brain, Boston University, Boston, MA 02215, USA
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