1
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Myrum C, Moreno-Castilla P, Rapp PR. 'Arc'-hitecture of normal cognitive aging. Ageing Res Rev 2022; 80:101678. [PMID: 35781092 PMCID: PMC9378697 DOI: 10.1016/j.arr.2022.101678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 06/10/2022] [Accepted: 06/24/2022] [Indexed: 12/17/2022]
Abstract
Arc is an effector immediate-early gene that is critical for forming long-term memories. Since its discovery 25 years ago, it has repeatedly surprised us with a number of intriguing properties, including the transport of its mRNA to recently-activated synapses, its master role in bidirectionally regulating synaptic strength, its evolutionary retroviral origins, its ability to mediate intercellular transfer between neurons via extracellular vesicles (EVs), and its exceptional regulation-both temporally and spatially. The current review discusses how Arc has been used as a tool to identify the neural networks involved in cognitive aging and how Arc itself may contribute to cognitive outcome in aging. In addition, we raise several outstanding questions, including whether Arc-containing EVs in peripheral blood might provide a noninvasive biomarker for memory-related synaptic failure in aging, and whether rectifying Arc dysregulation is likely to be an effective strategy for bending the arc of aging toward successful cognitive outcomes.
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Affiliation(s)
- Craig Myrum
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
| | - Perla Moreno-Castilla
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
| | - Peter R Rapp
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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2
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Babur E, Tufan E, Barutçu Ö, Aslan-Gülpınar AG, Tan B, Süer S, Dursun N. Neurodegeneration-Related Genes are Differentially Expressed in Middle-Aged Rats Compared to Young-Adult Rats Having Equal Performance on Long-Term Memory and Synaptic Plasticity. Brain Res Bull 2022; 182:90-101. [DOI: 10.1016/j.brainresbull.2022.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 01/13/2022] [Accepted: 02/08/2022] [Indexed: 11/25/2022]
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3
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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: 20] [Impact Index Per Article: 5.0] [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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4
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Cisneros-Franco JM, Voss P, Kang MS, Thomas ME, Côté J, Ross K, Gaudreau P, Rudko DA, Rosa-Neto P, de-Villers-Sidani É. PET Imaging of Perceptual Learning-Induced Changes in the Aged Rodent Cholinergic System. Front Neurosci 2020; 13:1438. [PMID: 32038142 PMCID: PMC6985428 DOI: 10.3389/fnins.2019.01438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/20/2019] [Indexed: 12/14/2022] Open
Abstract
The cholinergic system enhances attention and gates plasticity, making it a major regulator of adult learning. With aging, however, progressive degeneration of the cholinergic system impairs both the acquisition of new skills and functional recovery following neurological injury. Although cognitive training and perceptual learning have been shown to enhance auditory cortical processing, their specific impact on the cholinergic system remains unknown. Here we used [18F]FEOBV, a positron emission tomography (PET) radioligand that selectively binds to the vesicular acetylcholine transporter (VAChT), as a proxy to assess whether training on a perceptual task results in increased cholinergic neurotransmission. We show for the first time that perceptual learning is associated with region-specific changes in cholinergic neurotransmission, as detected by [18F]FEOBV PET imaging and corroborated with immunohistochemistry.
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Affiliation(s)
- J Miguel Cisneros-Franco
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Patrice Voss
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Min Su Kang
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Research Centre for Studies in Aging, McGill University, Montreal, QC, Canada
| | - Maryse E Thomas
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Jonathan Côté
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Karen Ross
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Pierrette Gaudreau
- Réseau Québécois de Recherche sur le Vieillissement, Université de Montréal, Montreal, QC, Canada
| | - David A Rudko
- Department of Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Pedro Rosa-Neto
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Research Centre for Studies in Aging, McGill University, Montreal, QC, Canada
| | - Étienne de-Villers-Sidani
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
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5
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Abstract
The prevalence of cognitive decline is increasing as the ageing population is considerably growing. Restricting this age-associated process has become a challenging public health issue. The age-related increase in oxidative stress plays a major role in cognitive decline, because of its harmful effect on functional plasticity of the brain, such as long-term potentiation (LTP). Here, we show that citrulline (Cit) has powerful antioxidant properties that can limit ex vivo oxidative stress-induced LTP impairment in the hippocampus. We also illustrate that a three-month Cit supplementation has a protective effect on LTP in aged rats in vivo. The identification of a Cit oxidation byproduct in vitro suggests that the antioxidant properties of Cit could result from its own oxidation. Cit supplementation may be a promising preventive nutritional approach to limit age-related cognitive decline.
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6
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Tan B, Babur E, Koşar B, Varol S, Dursun N, Süer C. Age-dependent evaluation of long-term depression responses in hyperthyroid rats: Possible roles of oxidative intracellular redox status. Brain Res 2019; 1720:146314. [DOI: 10.1016/j.brainres.2019.146314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/25/2019] [Accepted: 06/27/2019] [Indexed: 10/26/2022]
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7
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Miranda M, Morici JF, Zanoni MB, Bekinschtein P. Brain-Derived Neurotrophic Factor: A Key Molecule for Memory in the Healthy and the Pathological Brain. Front Cell Neurosci 2019; 13:363. [PMID: 31440144 PMCID: PMC6692714 DOI: 10.3389/fncel.2019.00363] [Citation(s) in RCA: 697] [Impact Index Per Article: 139.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/25/2019] [Indexed: 12/13/2022] Open
Abstract
Brain Derived Neurotrophic Factor (BDNF) is a key molecule involved in plastic changes related to learning and memory. The expression of BDNF is highly regulated, and can lead to great variability in BDNF levels in healthy subjects. Changes in BDNF expression are associated with both normal and pathological aging and also psychiatric disease, in particular in structures important for memory processes such as the hippocampus and parahippocampal areas. Some interventions like exercise or antidepressant administration enhance the expression of BDNF in normal and pathological conditions. In this review, we will describe studies from rodents and humans to bring together research on how BDNF expression is regulated, how this expression changes in the pathological brain and also exciting work on how interventions known to enhance this neurotrophin could have clinical relevance. We propose that, although BDNF may not be a valid biomarker for neurodegenerative/neuropsychiatric diseases because of its disregulation common to many pathological conditions, it could be thought of as a marker that specifically relates to the occurrence and/or progression of the mnemonic symptoms that are common to many pathological conditions.
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Affiliation(s)
- Magdalena Miranda
- Laboratory of Memory Research and Molecular Cognition, Institute for Cognitive and Translational Neuroscience, Instituto de Neurología Cognitiva, CONICET, Universidad Favaloro, Buenos Aires, Argentina
| | - Juan Facundo Morici
- Laboratory of Memory Research and Molecular Cognition, Institute for Cognitive and Translational Neuroscience, Instituto de Neurología Cognitiva, CONICET, Universidad Favaloro, Buenos Aires, Argentina
| | - María Belén Zanoni
- Laboratory of Memory Research and Molecular Cognition, Institute for Cognitive and Translational Neuroscience, Instituto de Neurología Cognitiva, CONICET, Universidad Favaloro, Buenos Aires, Argentina
| | - Pedro Bekinschtein
- Laboratory of Memory Research and Molecular Cognition, Institute for Cognitive and Translational Neuroscience, Instituto de Neurología Cognitiva, CONICET, Universidad Favaloro, Buenos Aires, Argentina
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8
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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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9
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Susceptibility to Aβo and TBOA of LTD and Extrasynaptic NMDAR-Dependent Tonic Current in the Aged Rat Hippocampus. Neurochem Res 2018; 44:692-702. [PMID: 30426348 DOI: 10.1007/s11064-018-2677-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 10/26/2018] [Accepted: 11/02/2018] [Indexed: 12/29/2022]
Abstract
Aging, as the major risk factor of Alzheimer's disease (AD), may increase susceptibility to neurodegenerative diseases through many gradual molecular and biochemical changes. Extracellular glutamate homeostasis and extrasynaptic glutamate N-methyl-D-aspartate receptors (NMDAR) are among early synaptic targets of oligomeric amyloid β (Aβo), one of the AD related synaptotoxic protein species. In this study, we asked for the effects of Aβo on long-term depression (LTD), a form of synaptic plasticity dependent on extrasynaptic NMDAR activation, and on a tonic current (TC) resulting from the activation of extrasynaptic NMDAR by ambient glutamate in hippocampal slices from young (3-6-month-old) and aged (24-28-month-old) Sprague-Dawley rats. Aβo significantly enhanced the magnitude of LTD and the amplitude of TC in aged slices compared to young ones. TBOA, a glutamate transporter inhibitor, also significantly increased LTD magnitude and TC amplitude in slices from aged rats, suggesting either an age-related weakness of the glutamate clearance system and/or a facilitated extrasynaptic NMDAR activation. From our present data, we hypothesize that senescence-related impairment of the extrasynaptic environment may be a vector of vulnerability of the aged hippocampus to neurodegenerative promotors such as Aβo.
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10
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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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11
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Castonguay D, Dufort-Gervais J, Ménard C, Chatterjee M, Quirion R, Bontempi B, Schneider JS, Arnsten AFT, Nairn AC, Norris CM, Ferland G, Bézard E, Gaudreau P, Lombroso PJ, Brouillette J. The Tyrosine Phosphatase STEP Is Involved in Age-Related Memory Decline. Curr Biol 2018; 28:1079-1089.e4. [PMID: 29576474 DOI: 10.1016/j.cub.2018.02.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/27/2017] [Accepted: 02/19/2018] [Indexed: 01/22/2023]
Abstract
Cognitive disabilities that occur with age represent a growing and expensive health problem. Age-associated memory deficits are observed across many species, but the underlying molecular mechanisms remain to be fully identified. Here, we report elevations in the levels and activity of the striatal-enriched phosphatase (STEP) in the hippocampus of aged memory-impaired mice and rats, in aged rhesus monkeys, and in people diagnosed with amnestic mild cognitive impairment (aMCI). The accumulation of STEP with aging is related to dysfunction of the ubiquitin-proteasome system that normally leads to the degradation of STEP. Higher level of active STEP is linked to enhanced dephosphorylation of its substrates GluN2B and ERK1/2, CREB inactivation, and a decrease in total levels of GluN2B and brain-derived neurotrophic factor (BDNF). These molecular events are reversed in aged STEP knockout and heterozygous mice, which perform similarly to young control mice in the Morris water maze (MWM) and Y-maze tasks. In addition, administration of the STEP inhibitor TC-2153 to old rats significantly improved performance in a delayed alternation T-maze memory task. In contrast, viral-mediated STEP overexpression in the hippocampus is sufficient to induce memory impairment in the MWM and Y-maze tests, and these cognitive deficits are reversed by STEP inhibition. In old LOU/C/Jall rats, a model of healthy aging with preserved memory capacities, levels of STEP and GluN2B are stable, and phosphorylation of GluN2B and ERK1/2 is unaltered. Altogether, these data suggest that elevated levels of STEP that appear with advancing age in several species contribute to the cognitive declines associated with aging.
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Affiliation(s)
- David Castonguay
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada
| | - Julien Dufort-Gervais
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada
| | - Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada; Department of Medecine, Université de Montréal, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC, Canada
| | - Manavi Chatterjee
- Child Study Center, Yale University School of Medicine, New Haven, CT, USA
| | - Rémi Quirion
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Bruno Bontempi
- Université de Bordeaux, UMR 5293, Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Jay S Schneider
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Amy F T Arnsten
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Christopher M Norris
- Department of Molecular and Biomedical Pharmacology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Guylaine Ferland
- Department of Nutrition, Université de Montréal, and Institut de Cardiologie de Montréal, Montreal, QC, Canada
| | - Erwan Bézard
- Université de Bordeaux, UMR 5293, Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Pierrette Gaudreau
- Department of Medecine, Université de Montréal, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC, Canada
| | - Paul J Lombroso
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Child Study Center, Yale University School of Medicine, New Haven, CT, USA.
| | - Jonathan Brouillette
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada; Child Study Center, Yale University School of Medicine, New Haven, CT, USA.
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12
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Sampedro-Piquero P, Álvarez-Suárez P, Begega A. Coping with Stress During Aging: The Importance of a Resilient Brain. Curr Neuropharmacol 2018; 16:284-296. [PMID: 28925881 PMCID: PMC5843980 DOI: 10.2174/1570159x15666170915141610] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/12/2017] [Accepted: 01/01/1970] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Resilience is the ability to achieve a positive outcome when we are in the face of adversity. It supposes an active resistance to adversity by coping mechanisms in which genetic, molecular, neural and environmental factors are involved. Resilience has been usually studied in early ages and few is known about it during aging. METHODS In this review, we will address the age-related changes in the brain mechanisms involved in regulating the stress response. Furthermore, using the EE paradigm, we analyse the resilient potential of this intervention and its neurobiological basis. In this case, we will focus on identifying the characteristics of a resilient brain (modifications in HPA structure and function, neurogenesis, specific neuron types, glia, neurotrophic factors, nitric oxide synthase or microRNAs, among others). RESULTS The evidence suggests that a healthy lifestyle has a crucial role to promote a resilient brain during aging. Along with the behavioral changes described, a better regulation of HPA axis, enhanced levels of postmitotic type-3 cells or changes in GABAergic neurotransmission are some of the brain mechanisms involved in resilience. CONCLUSION Future research should identify different biomarkers that increase the resistance to develop mood disorders and based on this knowledge, develop new potential therapeutic targets.
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Affiliation(s)
- P. Sampedro-Piquero
- Departamento de Psicobiología y Metodología de las CC, Facultad de Psicología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga, Spain
| | - P. Álvarez-Suárez
- Institute of Neuroscience of the Principality of Asturias (INEUROPA), Department of Psychology, University of Oviedo, Spain
| | - A. Begega
- Institute of Neuroscience of the Principality of Asturias (INEUROPA), Department of Psychology, University of Oviedo, Spain
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13
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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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14
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Picot M, Billard JM, Dombret C, Albac C, Karameh N, Daumas S, Hardin-Pouzet H, Mhaouty-Kodja S. Neural Androgen Receptor Deletion Impairs the Temporal Processing of Objects and Hippocampal CA1-Dependent Mechanisms. PLoS One 2016; 11:e0148328. [PMID: 26849367 PMCID: PMC4743963 DOI: 10.1371/journal.pone.0148328] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 01/15/2016] [Indexed: 12/04/2022] Open
Abstract
We studied the role of testosterone, mediated by the androgen receptor (AR), in modulating temporal order memory for visual objects. For this purpose, we used male mice lacking AR specifically in the nervous system. Control and mutant males were gonadectomized at adulthood and supplemented with equivalent amounts of testosterone in order to normalize their hormonal levels. We found that neural AR deletion selectively impaired the processing of temporal information for visual objects, without affecting classical object recognition or anxiety-like behavior and circulating corticosterone levels, which remained similar to those in control males. Thus, mutant males were unable to discriminate between the most recently seen object and previously seen objects, whereas their control littermates showed more interest in exploring previously seen objects. Because the hippocampal CA1 area has been associated with temporal memory for visual objects, we investigated whether neural AR deletion altered the functionality of this region. Electrophysiological analysis showed that neural AR deletion affected basal glutamate synaptic transmission and decreased the magnitude of N-methyl-D-aspartate receptor (NMDAR) activation and high-frequency stimulation-induced long-term potentiation. The impairment of NMDAR function was not due to changes in protein levels of receptor. These results provide the first evidence for the modulation of temporal processing of information for visual objects by androgens, via AR activation, possibly through regulation of NMDAR signaling in the CA1 area in male mice.
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Affiliation(s)
- Marie Picot
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Jean-Marie Billard
- Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, UMR 894, Paris, 75014 France
| | - Carlos Dombret
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Christelle Albac
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Nida Karameh
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Stéphanie Daumas
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Hélène Hardin-Pouzet
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
| | - Sakina Mhaouty-Kodja
- Neuroscience Paris Seine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche (UMR) S1130, Université P. et M. Curie, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Université P. et M. Curie, Paris, France
- Sorbonne Universités, Université P. et M. Curie UM CR18, Université Paris 06, France
- * E-mail:
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Moreno L, Rose C, Mohanraj A, Allinquant B, Billard JM, Dutar P. sAβPPα Improves Hippocampal NMDA-Dependent Functional Alterations Linked to Healthy Aging. J Alzheimers Dis 2015; 48:927-35. [DOI: 10.3233/jad-150297] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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16
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Gender- and region-dependent changes of redox biomarkers in the brain of successfully aging LOU/C rats. Mech Ageing Dev 2015; 149:19-30. [DOI: 10.1016/j.mad.2015.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 03/21/2015] [Accepted: 04/22/2015] [Indexed: 11/23/2022]
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Méquinion M, Chauveau C, Viltart O. The use of animal models to decipher physiological and neurobiological alterations of anorexia nervosa patients. Front Endocrinol (Lausanne) 2015; 6:68. [PMID: 26042085 PMCID: PMC4436882 DOI: 10.3389/fendo.2015.00068] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/15/2015] [Indexed: 12/18/2022] Open
Abstract
Extensive studies were performed to decipher the mechanisms regulating feeding due to the worldwide obesity pandemy and its complications. The data obtained might be adapted to another disorder related to alteration of food intake, the restrictive anorexia nervosa. This multifactorial disease with a complex and unknown etiology is considered as an awful eating disorder since the chronic refusal to eat leads to severe, and sometimes, irreversible complications for the whole organism, until death. There is an urgent need to better understand the different aspects of the disease to develop novel approaches complementary to the usual psychological therapies. For this purpose, the use of pertinent animal models becomes a necessity. We present here the various rodent models described in the literature that might be used to dissect central and peripheral mechanisms involved in the adaptation to deficient energy supplies and/or the maintenance of physiological alterations on the long term. Data obtained from the spontaneous or engineered genetic models permit to better apprehend the implication of one signaling system (hormone, neuropeptide, neurotransmitter) in the development of several symptoms observed in anorexia nervosa. As example, mutations in the ghrelin, serotonin, dopamine pathways lead to alterations that mimic the phenotype, but compensatory mechanisms often occur rendering necessary the use of more selective gene strategies. Until now, environmental animal models based on one or several inducing factors like diet restriction, stress, or physical activity mimicked more extensively central and peripheral alterations decribed in anorexia nervosa. They bring significant data on feeding behavior, energy expenditure, and central circuit alterations. Animal models are described and criticized on the basis of the criteria of validity for anorexia nervosa.
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Affiliation(s)
- Mathieu Méquinion
- INSERM UMR-S1172, Development and Plasticity of Postnatal Brain, Lille, France
| | - Christophe Chauveau
- Pathophysiology of Inflammatory Bone Diseases, EA 4490, University of the Littoral Opal Coast, Boulogne sur Mer, France
| | - Odile Viltart
- INSERM UMR-S1172, Early stages of Parkinson diseases, University Lille 1, Lille, France
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Yang YJ, Chen HB, Wei B, Wang W, Zhou PL, Zhan JQ, Hu MR, Yan K, Hu B, Yu B. Cognitive decline is associated with reduced surface GluR1 expression in the hippocampus of aged rats. Neurosci Lett 2015; 591:176-181. [DOI: 10.1016/j.neulet.2015.02.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/27/2015] [Accepted: 02/13/2015] [Indexed: 10/24/2022]
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Abstract
PURPOSE OF REVIEW The literature on the influence of dietary omega-3 polyunsaturated fatty acid (ω-3 PUFA) on brain aging has grown exponentially during the last decade. Many avenues have been explored but no global picture or clear evidence has emerged. Experimental studies have shown that ω-3 PUFA is involved in many neurobiological processes that are involved in neurotransmission and neuroprotection, indicating that these PUFAs may prevent age-related brain damage. Human studies have revealed only a weak link between ω-3 PUFA status and cognitive aging, whereas interventional studies have yet to confirm it. The purpose of this review is to analyze the developments in the area during the last 2 years. RECENT FINDINGS Human brain MRI studies have confirmed previous findings that ω-3 PUFA can protect the brain during aging; two intervention studies obtained clear evidence. We also analyzed the experimental data clarifying the involvement of ω-3 PUFA in neurotransmission, neuroprotection (including prevention of peroxidation, inflammation, and excitotoxicity), and neurogenesis, thereby helping the brain cope with aging. SUMMARY These recent human and experimental studies provide support for and clarification of how ω-3 PUFA protect against brain aging and highlight the main lines for future research.
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Affiliation(s)
- Isabelle Denis
- aUnité de Neurobiologie de l'Olfaction, NBO U1197, INRA, Jouy-en-Josas bINSERM UMR 894, Centre de Psychiatrie et Neurosciences, Paris cUnité MICALIS, UMR 1319, INRA, Jouy-en-Josas dUnité NutriNeurO, UMR INRA 1286, Université Victor Segalen Bordeaux 2, Bordeaux, France
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20
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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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Ménard C, Quirion R, Vigneault E, Bouchard S, Ferland G, El Mestikawy S, Gaudreau P. Glutamate presynaptic vesicular transporter and postsynaptic receptor levels correlate with spatial memory status in aging rat models. Neurobiol Aging 2014; 36:1471-82. [PMID: 25556161 DOI: 10.1016/j.neurobiolaging.2014.11.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/01/2014] [Accepted: 11/21/2014] [Indexed: 11/28/2022]
Abstract
In humans, memory capacities are generally affected with aging, even without any reported neurologic disorders. The mechanisms behind cognitive decline are not well understood. We studied here whether postsynaptic glutamate receptor and presynaptic vesicular glutamate transporters (VGLUTs) levels may change in the course of aging and be related to cognitive abilities using various age-impaired (AI) or age-unimpaired rat strains. Twenty-four-month-old Long-Evans (LE) rats with intact spatial memory maintained postsynaptic ionotropic glutamate receptor levels in the hippocampal-adjacent cortex similar to those of young animals. In contrast, AI rats showed significantly reduced expression of ionotropic glutamate receptor GluR2, NR2A and NR2B subunits. In AI LE rats, VGLUT1 and VGLUT2 levels were increased and negatively correlated with receptor levels as shown by principal component analysis and correlation matrices. We also investigated whether glutamatergic receptors and VGLUT levels were altered in the obesity-resistant LOU/C/Jall (LOU) rat strain which is characterized by intact memory despite aging. No difference was observed between 24-month-old LOU rats and their young counterparts. Taken together, the unaltered spatial memory performance of 24-month-old age-unimpaired LE and LOU rats suggests that intact coordination of the presynaptic and postsynaptic hippocampal-adjacent cortex glutamatergic networks may be important for successful cognitive aging. Accordingly, altered expression of presynaptic and postsynaptic glutamatergic components, such as in AI LE rats, could be considered a marker of age-related cognitive deficits.
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Affiliation(s)
- Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada; Laboratory of Neuroendocrinology of Aging, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, Quebec, Canada; Department of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Rémi Quirion
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Erika Vigneault
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Sylvain Bouchard
- Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Guylaine Ferland
- Institut Universitaire de Gériatrie de Montréal Research Center, University of Montreal, Montreal, Quebec, Canada; Department of Nutrition, University of Montreal, Montreal, Quebec, Canada
| | - Salah El Mestikawy
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada; INSERM U952, CNRS UMR7224, Université Pierre et Marie Curie, Paris, France
| | - Pierrette Gaudreau
- Laboratory of Neuroendocrinology of Aging, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, Quebec, Canada; Department of Medicine, University of Montreal, Montreal, Quebec, Canada.
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Ménard C, Quirion R, Bouchard S, Ferland G, Gaudreau P. Glutamatergic signaling and low prodynorphin expression are associated with intact memory and reduced anxiety in rat models of healthy aging. Front Aging Neurosci 2014; 6:81. [PMID: 24847259 PMCID: PMC4019859 DOI: 10.3389/fnagi.2014.00081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/16/2014] [Indexed: 11/13/2022] Open
Abstract
The LOU/C/Jall (LOU) rat strain is considered a model of healthy aging due to its increased longevity, maintenance of stable body weight (BW) throughout life and low incidence of age-related diseases. However, aging LOU rat cognitive and anxiety status has yet to be investigated. In the present study, male and female LOU rat cognitive performances (6-42 months) were assessed using novel object recognition and Morris Water Maze tasks. Recognition memory remained intact in all LOU rats up to 42 months of age. As for spatial memory, old LOU rat performed similarly as young animals for learning acquisition, reversal learning, and retention. While LOU rat BW remained stable despite aging, 20-month-old ad-libitum-fed (OAL) male Sprague Dawley rats become obese. We determined if long-term caloric restriction (LTCR) prevents age-related BW increase and cognitive deficits in this rat strain, as observed in the obesity-resistant LOU rats. Compared to young animals, recognition memory was impaired in OAL but intact in 20-month-old calorie-restricted (OCR) rats. Similarly, OAL spatial learning acquisition was impaired but LTCR prevented the deficits. Exacerbated stress responses may favor age-related cognitive decline. In the elevated plus maze and open field tasks, LOU and OCR rats exhibited high levels of exploratory activity whereas OAL rats displayed anxious behaviors. Expression of prodynorphin (Pdyn), an endogenous peptide involved in stress-related memory impairments, was increased in the hippocampus of OAL rats. Group 1 metabotropic glutamate receptor 5 and immediate early genes Homer 1a and Arc expression, both associated with successful cognitive aging, were unaltered in aging LOU rats but lower in OAL than OCR rats. Altogether, our results, supported by principal component analysis and correlation matrix, suggest that intact memory and low anxiety are associated with glutamatergic signaling and low Pdyn expression in the hippocampus of non-obese aging rats.
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Affiliation(s)
- Caroline Ménard
- Neuroscience Division, Douglas Mental Health University Institute Research Center Montreal, QC, Canada ; Department of Psychiatry, McGill University Montreal, QC, Canada ; Laboratory of Neuroendocrinology of Aging, Centre Hospitalier de l'Université de Montréal Research Center Montreal, QC, Canada ; Department of Medicine, University of Montreal Montreal, QC, Canada
| | - Rémi Quirion
- Neuroscience Division, Douglas Mental Health University Institute Research Center Montreal, QC, Canada ; Department of Psychiatry, McGill University Montreal, QC, Canada
| | - Sylvain Bouchard
- Faculty of Medicine, University of Montreal Montreal, QC, Canada
| | - Guylaine Ferland
- Hôpital du Sacré-Coeur de Montréal Research Center Montreal, QC, Canada ; Department of Nutrition, University of Montreal Montreal, QC, Canada
| | - Pierrette Gaudreau
- Laboratory of Neuroendocrinology of Aging, Centre Hospitalier de l'Université de Montréal Research Center Montreal, QC, Canada ; Department of Medicine, University of Montreal Montreal, QC, Canada
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Mechanisms underlying the neuroprotective effect of brain reserve against late life depression. J Neural Transm (Vienna) 2014; 122 Suppl 1:S55-61. [PMID: 24390152 DOI: 10.1007/s00702-013-1154-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 12/25/2013] [Indexed: 02/07/2023]
Abstract
Depression is common and medically relevant illness that has been associated to a state of "accelerated aging" and can significantly compromise successful aging. In recent years, the concept of "brain reserve" has emerged to describe some individuals having an increased "baseline adaptive neuroplasticity", providing greater dynamic capacity for adjusting and remodeling cortical circuits to various stressors. We hypothesize that brain reserve may have neuroprotective effects against late life depression. Here, we discuss the modulatory capacity of stress and corticosteroid hormones on hippocampal plasticity and neuronal viability in late life depression as well as the anti-depressive of ketamine and scopolamine mediated by stimulation of the mammalian target of rapamycin, increased inhibitory phosphorylation of GSK-3β, and increased synaptogenesis. This review shall shed light on complex neurobiological mechanisms that underpin late life depression and help to better understand neural correlates of resilience. Investigating how rat models of increased cognitive reserve mitigate a chronic mild stress-elicited depression will afford new insights in the search for new therapeutic targets to treat this neuropsychiatric disorder.
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Decorps J, Saumet JL, Sommer P, Sigaudo-Roussel D, Fromy B. Effect of ageing on tactile transduction processes. Ageing Res Rev 2014; 13:90-9. [PMID: 24373814 DOI: 10.1016/j.arr.2013.12.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 12/02/2013] [Accepted: 12/16/2013] [Indexed: 01/09/2023]
Abstract
With advancing age, a decline in the main sensory modalities including touch sensation and perception is well reported to occur. This review mainly outlines the peripheral components of touch perception highlighting ageing influences on morphological and functional features of cutaneous mechanical transducers and mechanosensitive ion channels, sensory innervation, neurotransmitters and even vascular system required to ensure efferent function of the afferent nerve fibres in the skin. This, in conjunction with effect of ageing on the skin per se and central nervous system, could explain the tactile deficit seen among the ageing population. We also discuss appropriate tools and experimental models available to study the age-related tactile decline.
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Affiliation(s)
- Johanna Decorps
- Laboratory of Tissue Biology and Therapeutic Engineering, Centre National de la Recherche Scientifique (CNRS) UMR 5305, Lyon, France; University of Lyon 1, UMR 5305, Lyon, France.
| | - Jean Louis Saumet
- Laboratory of Tissue Biology and Therapeutic Engineering, Centre National de la Recherche Scientifique (CNRS) UMR 5305, Lyon, France; University of Lyon 1, UMR 5305, Lyon, France.
| | - Pascal Sommer
- Laboratory of Tissue Biology and Therapeutic Engineering, Centre National de la Recherche Scientifique (CNRS) UMR 5305, Lyon, France; University of Lyon 1, UMR 5305, Lyon, France.
| | - Dominique Sigaudo-Roussel
- Laboratory of Tissue Biology and Therapeutic Engineering, Centre National de la Recherche Scientifique (CNRS) UMR 5305, Lyon, France; University of Lyon 1, UMR 5305, Lyon, France.
| | - Berengere Fromy
- Laboratory of Tissue Biology and Therapeutic Engineering, Centre National de la Recherche Scientifique (CNRS) UMR 5305, Lyon, France; University of Lyon 1, UMR 5305, Lyon, France.
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Marissal-Arvy N, Hamiani R, Richard E, Moisan MP, Pallet V. Vitamin A regulates hypothalamic-pituitary-adrenal axis status in LOU/C rats. J Endocrinol 2013; 219:21-7. [PMID: 23847298 DOI: 10.1530/joe-13-0062] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The aim of this study was to explore the involvement of retinoids in the hypoactivity and hyporeactivity to stress of the hypothalamic-pituitary-adrenal (HPA) axis in LOU/C rats. We measured the effects of vitamin A deficiency administered or not with retinoic acid (RA) on plasma corticosterone in standard conditions and in response to restraint stress and on hypothalamic and hippocampal expression of corticosteroid receptors, corticotropin-releasing hormone and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in LOU/C rats. Interestingly, under control conditions, we measured a higher plasma concentration of retinol in LOU/C than in Wistar rats, which could contribute to the lower basal activity of the HPA axis in LOU/C rats. Vitamin A deficiency induced an increased HPA axis activity in LOU/C rats, normalized by RA administration. Compared with LOU/C control rats, vitamin A-deficient rats showed a delayed and heightened corticosterone response to restraint stress. The expression of corticosteroid receptors was strongly decreased by vitamin A deficiency in the hippocampus, which could contribute to a less efficient feedback by corticosterone on HPA axis tone. The expression of 11β-HSD1 was increased by vitamin A deficiency in the hypothalamus (+62.5%) as in the hippocampus (+104.7%), which could lead to a higher production of corticosterone locally and contribute to alteration of the hippocampus. RA supplementation treatment restored corticosterone concentrations and 11β-HSD1 expression to control levels. The high vitamin A status of LOU/C rats could contribute to their low HPA axis activity/reactivity and to a protective effect against 11β-HSD1-mediated deleterious action on cognitive performances during ageing.
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Affiliation(s)
- Nathalie Marissal-Arvy
- INRA, Nutrition and Integrative Neurobiology, UMR1286, Université de Bordeaux 2, 146, rue Léo Saignat, 33076 Bordeaux Cedex, France
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Sama DM, Norris CM. Calcium dysregulation and neuroinflammation: discrete and integrated mechanisms for age-related synaptic dysfunction. Ageing Res Rev 2013; 12:982-95. [PMID: 23751484 PMCID: PMC3834216 DOI: 10.1016/j.arr.2013.05.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/27/2013] [Accepted: 05/30/2013] [Indexed: 12/30/2022]
Abstract
Some of the best biomarkers of age-related cognitive decline are closely linked to synaptic function and plasticity. This review highlights several age-related synaptic alterations as they relate to Ca(2+) dyshomeostasis, through elevation of intracellular Ca(2+), and neuroinflammation, through production of pro-inflammatory cytokines including interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Though distinct in many ways, Ca(2+) and neuroinflammatory signaling mechanisms exhibit extensive cross-talk and bidirectional interactions. For instance, cytokine production in glial cells is strongly dependent on the Ca(2+) dependent protein phosphatase calcineurin, which shows elevated activity in animal models of aging and disease. In turn, pro-inflammatory cytokines, such as TNF, can augment the expression/activity of L-type voltage sensitive Ca(2+) channels in neurons, leading to Ca(2+) dysregulation, hyperactive calcineurin activity, and synaptic depression. Thus, in addition to discussing unique contributions of Ca(2+) dyshomeostasis and neuroinflammation, this review emphasizes how these processes interact to hasten age-related synaptic changes.
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Affiliation(s)
- Diana M Sama
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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27
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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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28
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Omega-3 fatty acids and brain resistance to ageing and stress: body of evidence and possible mechanisms. Ageing Res Rev 2013; 12:579-94. [PMID: 23395782 DOI: 10.1016/j.arr.2013.01.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/25/2013] [Accepted: 01/28/2013] [Indexed: 12/11/2022]
Abstract
The increasing life expectancy in the populations of rich countries raises the pressing question of how the elderly can maintain their cognitive function. Cognitive decline is characterised by the loss of short-term memory due to a progressive impairment of the underlying brain cell processes. Age-related brain damage has many causes, some of which may be influenced by diet. An optimal diet may therefore be a practical way of delaying the onset of age-related cognitive decline. Nutritional investigations indicate that the ω-3 poyunsaturated fatty acid (PUFA) content of western diets is too low to provide the brain with an optimal supply of docosahexaenoic acid (DHA), the main ω-3 PUFA in cell membranes. Insufficient brain DHA has been associated with memory impairment, emotional disturbances and altered brain processes in rodents. Human studies suggest that an adequate dietary intake of ω-3 PUFA can slow the age-related cognitive decline and may also protect against the risk of senile dementia. However, despite the many studies in this domain, the beneficial impact of ω-3 PUFA on brain function has only recently been linked to specific mechanisms. This review examines the hypothesis that an optimal brain DHA status, conferred by an adequate ω-3 PUFA intake, limits age-related brain damage by optimizing endogenous brain repair mechanisms. Our analysis of the abundant literature indicates that an adequate amount of DHA in the brain may limit the impact of stress, an important age-aggravating factor, and influences the neuronal and astroglial functions that govern and protect synaptic transmission. This transmission, particularly glutamatergic neurotransmission in the hippocampus, underlies memory formation. The brain DHA status also influences neurogenesis, nested in the hippocampus, which helps maintain cognitive function throughout life. Although there are still gaps in our knowledge of the way ω-3 PUFA act, the mechanistic studies reviewed here indicate that ω-3 PUFA may be a promising tool for preventing age-related brain deterioration.
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Paban V, Billard JM, Bouet V, Freret T, Boulouard M, Chambon C, Loriod B, Alescio-Lautier B. Genomic transcriptional profiling in LOU/C/Jall rats identifies genes for successful aging. Brain Struct Funct 2012; 218:1501-12. [DOI: 10.1007/s00429-012-0472-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/25/2012] [Indexed: 02/04/2023]
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30
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Ménard C, Quirion R. Group 1 metabotropic glutamate receptor function and its regulation of learning and memory in the aging brain. Front Pharmacol 2012; 3:182. [PMID: 23091460 PMCID: PMC3469824 DOI: 10.3389/fphar.2012.00182] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 09/23/2012] [Indexed: 12/22/2022] Open
Abstract
Normal aging is generally characterized by a slow decline of cognitive abilities albeit with marked individual differences. Several animal models have been studied to explore the molecular and cellular mechanisms underlying this phenomenon. The excitatory neurotransmitter glutamate and its receptors have been closely linked to spatial learning and hippocampus-dependent memory processes. For decades, ionotropic glutamate receptors have been known to play a critical role in synaptic plasticity, a form of adaptation regulating memory formation. Over the past 10 years, several groups have shown the importance of group 1 metabotropic glutamate receptor (mGluR) in successful cognitive aging. These G-protein-coupled receptors are enriched in the hippocampal formation and interact physically with other proteins in the membrane including glutamate ionotropic receptors. Synaptic plasticity is crucial to maintain cognitive abilities and long-term depression (LTD) induced by group 1 mGluR activation, which has been linked to memory in the aging brain. The translation and synthesis of proteins by mGluR-LTD modulate ionotropic receptor trafficking and expression of immediate early genes related to cognition. Fragile X syndrome, a genetic form of autism characterized by memory deficits, has been associated to mGluR receptor malfunction and aberrant activation of its downstream signaling pathways. Dysfunction of mGluR could also be involved in neurodegenerative disorders like Alzheimer’s disease (AD). Indeed, beta-amyloid, the main component of insoluble senile plaques and one of the hallmarks of AD, occludes mGluR-dependent LTD leading to diminished functional synapses. This review highlights recent findings regarding mGluR signaling, related synaptic plasticity, and their potential involvement in normal aging and neurological disorders.
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Affiliation(s)
- Caroline Ménard
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University Montreal, QC, Canada
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31
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Bouji M, Lecomte A, Hode Y, de Seze R, Villégier AS. Effects of 900 MHz radiofrequency on corticosterone, emotional memory and neuroinflammation in middle-aged rats. Exp Gerontol 2012; 47:444-51. [PMID: 22507567 DOI: 10.1016/j.exger.2012.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 03/21/2012] [Accepted: 03/23/2012] [Indexed: 01/02/2023]
Abstract
The widespread use of mobile phones raises the question of the effects of electromagnetic fields (EMF, 900 MHz) on the brain. Previous studies reported increased levels of the glial fibrillary acidic protein (GFAP) in the rat's brain after a single exposure to 900 MHz global system for mobile (GSM) signal, suggesting a potential inflammatory process. While this result was obtained in adult rats, no data is currently available in older animals. Since the transition from middle-age to senescence is highly dependent on environment and lifestyle, we studied the reactivity of middle-aged brains to EMF exposure. We assessed the effects of a single 15 min GSM exposure (900 MHz; specific absorption rate (SAR)=6 W/kg) on GFAP expression in young adults (6 week-old) and middle-aged rats (12 month-old). Brain interleukin (IL)-1β and IL-6, plasmatic levels of corticosterone (CORT), and emotional memory were also assessed. Our data indicated that, in contrast to previously published work, acute GSM exposure did not induce astrocyte activation. Our results showed an IL-1β increase in the olfactory bulb and enhanced contextual emotional memory in GSM-exposed middle-aged rats, and increased plasmatic levels of CORT in GSM-exposed young adults. Altogether, our data showed an age dependency of reactivity to GSM exposure in neuro-immunity, stress and behavioral parameters. Reproducing these effects and studying their mechanisms may allow a better understanding of mobile phone EMF effects on neurobiological parameters.
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Affiliation(s)
- Marc Bouji
- Unité de Toxicologie Expérimentale, Institut National de l'Environnement Industriel et des Risques, Parc Technologique ALATA, BP no. 2, 60550 Verneuil-en-Halatte, France
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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: 69] [Impact Index Per Article: 5.8] [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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Successful cognitive aging in rats: a role for mGluR5 glutamate receptors, homer 1 proteins and downstream signaling pathways. PLoS One 2012; 7:e28666. [PMID: 22238580 PMCID: PMC3253083 DOI: 10.1371/journal.pone.0028666] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 11/12/2011] [Indexed: 01/08/2023] Open
Abstract
Normal aging is associated with impairments in cognition, especially learning and memory. However, major individual differences are known to exist. Using the classical Morris Water Maze (MWM) task, we discriminated a population of 24-months old Long Evans aged rats in two groups--memory-impaired (AI) and memory-unimpaired (AU) in comparison with 6-months old adult animals. AI rats presented deficits in learning, reverse memory and retention. At the molecular level, an increase in metabotropic glutamate receptors 5 (mGluR5) was observed in post-synaptic densities (PSD) in the hippocampus of AU rats after training. Scaffolding Homer 1b/c proteins binding to group 1 mGluR facilitate coupling with its signaling effectors while Homer 1a reduces it. Both Homer 1a and 1b/c levels were up-regulated in the hippocampus PSD of AU animals following MWM task. Using immunohistochemistry we further demonstrated that mGluR5 as well as Homer 1b/c stainings were enhanced in the CA1 hippocampus sub-field of AU animals. In fact mGluR5 and Homer 1 isoforms were more abundant and co-localized in the hippocampal dendrites in AU rats. However, the ratio of Homer 1a/Homer 1b/c bound to mGluR5 in the PSD was four times lower for AU animals compared to AI rats. Consequently, AU animals presented higher PKCγ, ERK, p70S6K, mTOR and CREB activation. Finally the expression of immediate early gene Arc/Arg3.1 was shown to be higher in AU rats in accordance with its role in spatial memory consolidation. On the basis of these results, a model of successful cognitive aging with a critical role for mGluR5, Homer 1 proteins and downstream signalling pathways is proposed here.
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Escobar M, Crouzin N, Cavalier M, Quentin J, Roussel J, Lanté F, Batista-Novais AR, Cohen-Solal C, De Jesus Ferreira MC, Guiramand J, Barbanel G, Vignes M. Early, time-dependent disturbances of hippocampal synaptic transmission and plasticity after in utero immune challenge. Biol Psychiatry 2011; 70:992-9. [PMID: 21377655 DOI: 10.1016/j.biopsych.2011.01.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 01/10/2011] [Accepted: 01/11/2011] [Indexed: 11/17/2022]
Abstract
BACKGROUND Maternal infection during pregnancy is a recognized risk factor for the occurrence of a broad spectrum of psychiatric and neurologic disorders, including schizophrenia, autism, and cerebral palsy. Prenatal exposure of rats to lipopolysaccharide (LPS) leads to impaired learning and psychotic-like behavior in mature offspring, together with an enduring modification of glutamatergic excitatory synaptic transmission. The question that arises is whether any alterations of excitatory transmission and plasticity occurred at early developmental stages after in utero LPS exposure. METHODS Electrophysiological experiments were carried out on the CA1 area of hippocampal slices from prenatally LPS-exposed male offspring from 4 to 190 days old to study the developmental profiles of long-term depression (LTD) triggered by delivering 900 shocks either single- or paired-pulse (50-msec interval) at 1 Hz and the N-methyl-D-aspartate receptor (NMDAr) contribution to synaptic transmission. RESULTS The age-dependent drop of LTD is accelerated in prenatally LPS-exposed animals, and LTD is transiently converted into a slow-onset long-term potentiation between 16 and 25 days old. This long-term potentiation depends on Group I metabotropic glutamate receptors and protein kinase A activations and is independent of NMDArs. Maternal LPS challenge also leads to a rapid developmental impairment of synaptic NMDArs. This was associated with a concomitant reduced expression of GluN1, without any detectable alteration in the developmental switch of NMDAr GluN2 subunits. CONCLUSIONS Aberrant forms of synaptic plasticity can be detected at early developmental stages after prenatal LPS challenge concomitant with a clear hypo-functioning of the NMDAr in the hippocampus. This might result in later-occurring brain dysfunctions.
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Affiliation(s)
- Marion Escobar
- Institut des Biomolécules Max Mousseron, Montpellier, France
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Marissal-Arvy N, Langlois A, Tridon C, Mormede P. Functional variability in corticosteroid receptors is a major component of strain differences in fat deposition and metabolic consequences of enriched diets in rat. Metabolism 2011; 60:706-19. [PMID: 20723946 DOI: 10.1016/j.metabol.2010.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 06/11/2010] [Accepted: 07/08/2010] [Indexed: 02/01/2023]
Abstract
We aimed to distinguish mineralocorticoid (MR) from glucocorticoid receptor (GR) actions in the nutritional differences between the Fischer 344 (F344) and LOU/C (LOU) rat strains. The decrease of urinary Na+/K+ ratio induced via MR activation by aldosterone and decrease of circulating lymphocyte counts exerted via GR activation by dexamethasone revealed a higher efficiency of corticosteroid receptor in LOU than in F344 rats. Afterward, we submitted F344 and LOU male rats to adrenalectomy and to substitution treatments with agonists of MR or GR under 3 successive diets--standard, free choice between chow and pork lard, and an imposed high-fat/high-sugar diet--to explore the involvement of the interactions between activation of corticosteroid receptors and diet on food intake, body composition, and metabolic blood parameters in these rats. Lastly, we measured energy expenditure and substrate oxidization in various experimental conditions in LOU and F344 rats by indirect calorimetry. In LOU rats, we showed greater basal and MR-induced energy expenditure, diet-induced thermogenesis, and lipid oxidization. We showed that the F344 rat strain constitutes a relevant model of the unfavorable effects exerted by glucocorticoids via GR on food preference for high-calorie diets, abdominal fat deposition, diabetes, and other deleterious consequences of visceral obesity. Contrary to F344 rats, the LOU rats did not exhibit the expected visceral fat deposition linked to GR activation. This strain is therefore a relevant model of resistance to diet-induced obesity and to the deleterious effects exerted by glucocorticoids on metabolism.
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Affiliation(s)
- Nathalie Marissal-Arvy
- Université de Bordeaux 2, Laboratoire PsyNuGen, 146 rue Léo-Saignat, INRA UMR1286, CNRS UMR5226, F-33076 Bordeaux, France.
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Dubeau S, Ferland G, Gaudreau P, Beaumont E, Lesage F. Cerebrovascular hemodynamic correlates of aging in the Lou/c rat: a model of healthy aging. Neuroimage 2011; 56:1892-901. [PMID: 21497659 DOI: 10.1016/j.neuroimage.2011.03.076] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 03/07/2011] [Accepted: 03/28/2011] [Indexed: 11/18/2022] Open
Abstract
The LOU/c rat is an inbred strain considered a model of healthy aging. It exhibits a longer free disease lifespan and a low adiposity throughout life. While this animal model has been shown to maintain eating behavior and neuroendocrine, metabolic and cognitive functions with age, no study has yet investigated vascular correlates in this model of healthy aging. In the present work, multispectral optical imaging was used to investigate the hemodynamic response in the somatosensory cortex of LOU/c rats following forepaw stimulation in three age groups, 4, 24 and 40months. Results indicate reduced hemodynamic responses in the contralateral somatosensory cortex between young (4months) and older groups following stimulation. This decrease was associated with an increase in the spatial extent of activation. The ipsilateral response did not change with aging leading to decreased laterality. Estimations of the relative change in the local cerebral metabolic rate of oxygen during stimulation based on multimodal data showed no significant change with age. The exponent describing the relation between blood volume and blood flow changes, Grubb's parameter, did display a significant change with age which may suggest vessel compliance modifications. This work finds its relevance in recent findings underlying the importance of vascular changes with aging and its impact on neurodegenerative disease.
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Affiliation(s)
- S Dubeau
- Electrical Engineering Department, Ecole Polytechnique Montréal, Montreal, Quebec, Canada
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Potier B, Billard JM, Rivière S, Sinet PM, Denis I, Champeil-Potokar G, Grintal B, Jouvenceau A, Kollen M, Dutar P. Reduction in glutamate uptake is associated with extrasynaptic NMDA and metabotropic glutamate receptor activation at the hippocampal CA1 synapse of aged rats. Aging Cell 2010; 9:722-35. [PMID: 20569241 DOI: 10.1111/j.1474-9726.2010.00593.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
This study aims to determine whether the regulation of extracellular glutamate is altered during aging and its possible consequences on synaptic transmission and plasticity. A decrease in the expression of the glial glutamate transporters GLAST and GLT-1 and reduced glutamate uptake occur in the aged (24-27 months) Sprague-Dawley rat hippocampus. Glutamatergic excitatory postsynaptic potentials recorded extracellularly in ex vivo hippocampal slices from adult (3-5 months) and aged rats are depressed by DL-TBOA, an inhibitor of glutamate transporter activity, in an N-Methyl-d-Aspartate (NMDA)-receptor-dependent manner. In aged but not in young rats, part of the depressing effect of DL-TBOA also involves metabotropic glutamate receptor (mGluRs) activation as it is significantly reduced by the specific mGluR antagonist d-methyl-4-carboxy-phenylglycine (MCPG). The paired-pulse facilitation ratio, a functional index of glutamate release, is reduced by MCPG in aged slices to a level comparable to that in young rats both under control conditions and after being enhanced by DL-TBOA. These results suggest that the age-associated glutamate uptake deficiency favors presynaptic mGluR activation that lowers glutamate release. In parallel, 2 Hz-induced long-term depression is significantly decreased in aged animals and is fully restored by MCPG. All these data indicate a facilitated activation of extrasynaptic NMDAR and mGluRs in aged rats, possibly because of an altered distribution of glutamate in the extrasynaptic space. This in turn affects synaptic transmission and plasticity within the aged hippocampal CA1 network.
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Affiliation(s)
- Brigitte Potier
- Université Paris Descartes, Centre de Psychiatrie et de Neurosciences, UMR, Paris, France.
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Billard JM. Long-term depression in the hippocampal CA1 area of aged rats, revisited: contribution of temporal constraints related to slice preparation. PLoS One 2010; 5:e9843. [PMID: 20352095 PMCID: PMC2844418 DOI: 10.1371/journal.pone.0009843] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 03/02/2010] [Indexed: 01/10/2023] Open
Abstract
Background The effects of low-frequency conditioning stimulation (LFS, 900 pulses at 1 Hz) of glutamatergic afferents in CA1 hippocampal area using slices from two different strains of adult (3–5 month-old) and aged (23–27 month-old) rats were reinvestigated regarding the discrepancies in the literature concerning the expression of long-term depression (LTD) in the aging brain. Methodology/Principal Findings N-methyl-D-aspartate receptor (NMDA-R) dependent LTD was examined in both adult (n = 21) and aged (n = 22) Sprague-Dawley rats. While equivalent amounts of LTD could be obtained in both ages, there was significant variability depending upon the time between the slices were made and when they were tested. LTD was not apparent if slices were tested within 3 hours of dissection. The amount of LTD increased over the next three hours but more in adult than in aged rats. This age-related impairment was abolished by exogenous d-serine, thus reflecting the reduced activation of the NMDA-R glycine-binding site by the endogenous agonist in aged rats. Then, the amount of LTD reached asymptote at 5–7 hours following dissection. Similar temporal profiles of LTD expression were seen in young and aged Wistar rats. Conclusions/Significance Taken together, these results sound a cautionary note regarding the existence of an experimental “window of opportunity” for studying the effects of aging on LTD expression in hippocampal slice preparation.
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Affiliation(s)
- Jean-marie Billard
- Faculté de Médecine René Descartes, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, UMR894, Paris, France.
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Potier B, Turpin FR, Sinet PM, Rouaud E, Mothet JP, Videau C, Epelbaum J, Dutar P, Billard JM. Contribution of the d-Serine-Dependent Pathway to the Cellular Mechanisms Underlying Cognitive Aging. Front Aging Neurosci 2010; 2:1. [PMID: 20552041 PMCID: PMC2874399 DOI: 10.3389/neuro.24.001.2010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/07/2010] [Indexed: 01/04/2023] Open
Abstract
An association between age-related memory impairments and changes in functional plasticity in the aging brain has been under intense study within the last decade. In this article, we show that an impaired activation of the strychnine-insensitive glycine site of N-methyl-d-aspartate receptors (NMDA-R) by its agonist d-serine contributes to deficits of synaptic plasticity in the hippocampus of memory-impaired aged rats. Supplementation with exogenous d-serine prevents the age-related deficits of isolated NMDA-R-dependent synaptic potentials as well as those of theta-burst-induced long-term potentiation and synaptic depotentiation. Endogenous levels of d-serine are reduced in the hippocampus with aging, that correlates with a weaker expression of serine racemase synthesizing the amino acid. On the contrary, the affinity of d-serine binding to NMDA-R is not affected by aging. These results point to a critical role for the d-serine-dependent pathway in the functional alterations of the brain underlying memory impairment and provide key information in the search for new therapeutic strategies for the treatment of memory deficits in the elderly.
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Affiliation(s)
- B Potier
- Centre de Psychiatrie et Neurosciences, INSERM, U894, Faculté de Médecine, Université Paris Descartes Paris, France
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