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Heuer SE, Bloss EB, Howell GR. Strategies to dissect microglia-synaptic interactions during aging and in Alzheimer's disease. Neuropharmacology 2024; 254:109987. [PMID: 38705570 DOI: 10.1016/j.neuropharm.2024.109987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/29/2024] [Accepted: 05/02/2024] [Indexed: 05/07/2024]
Abstract
Age is the largest risk factor for developing Alzheimer's disease (AD), a neurodegenerative disorder that causes a progressive and severe dementia. The underlying cause of cognitive deficits seen in AD is thought to be the disconnection of neural circuits that control memory and executive functions. Insight into the mechanisms by which AD diverges from normal aging will require identifying precisely which cellular events are driven by aging and which are impacted by AD-related pathologies. Since microglia, the brain-resident macrophages, are known to have critical roles in the formation and maintenance of neural circuits through synaptic pruning, they are well-positioned to modulate synaptic connectivity in circuits sensitive to aging or AD. In this review, we provide an overview of the current state of the field and on emerging technologies being employed to elucidate microglia-synaptic interactions in aging and AD. We also discuss the importance of leveraging genetic diversity to study how these interactions are shaped across more realistic contexts. We propose that these approaches will be essential to define specific aging- and disease-relevant trajectories for more personalized therapeutics aimed at reducing the effects of age or AD pathologies on the brain. This article is part of the Special Issue on "Microglia".
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Affiliation(s)
- Sarah E Heuer
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Erik B Bloss
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
| | - Gareth R Howell
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
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2
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Chen PY, Shen M, Cai SQ, Tang ZW. Association Between Atopic Dermatitis and Aging: Clinical Observations and Underlying Mechanisms. J Inflamm Res 2024; 17:3433-3448. [PMID: 38828054 PMCID: PMC11144009 DOI: 10.2147/jir.s467099] [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: 03/29/2024] [Accepted: 05/17/2024] [Indexed: 06/05/2024] Open
Abstract
As one of the most prevalent chronic inflammatory skin diseases, atopic dermatitis (AD) increasingly affects the aging population. Amid the ongoing global aging trend, it's essential to recognize the intricate relationship between AD and aging. This paper reviews existing knowledge, summarizing clinical observations of associations between AD and aging-related diseases in various systems, including endocrine, cardiovascular, and neurological. Additionally, it discusses major theories explaining the correlation, encompassing skin-mucosal barriers, systemic inflammation and stress, genes, signal transduction, and environmental and behavioral factors. The association between AD and aging holds significant importance, both in population and basic perspectives. While further research is warranted, this paper aims to inspire deeper exploration of inflammation/allergy-aging dynamics and the timely management of elderly patients with AD.
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Affiliation(s)
- Peng-Yu Chen
- Department of Dermatology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, People’s Republic of China
| | - Minxue Shen
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, 410008, People’s Republic of China
- Hunan Engineering Research Center of Skin Health and Disease; Hunan Key Laboratory of Skin Cancer and Psoriasis (Xiangya Hospital), Changsha, 410008, People’s Republic of China
- Department of Social Medicine and Health Management, Xiangya School of Public Health, Central South University, Changsha, 410078, People’s Republic of China
| | - Sui-Qing Cai
- Department of Dermatology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, People’s Republic of China
| | - Zhen-Wei Tang
- Department of Dermatology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, People’s Republic of China
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3
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Li S, Rosen MC, Chang S, David S, Freedman DJ. Alterations of neural activity in the prefrontal cortex associated with deficits in working memory performance. Front Behav Neurosci 2023; 17:1213435. [PMID: 37915531 PMCID: PMC10616307 DOI: 10.3389/fnbeh.2023.1213435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/31/2023] [Indexed: 11/03/2023] Open
Abstract
Working memory (WM), a core cognitive function, enables the temporary holding and manipulation of information in mind to support ongoing behavior. Neurophysiological recordings conducted in nonhuman primates have revealed neural correlates of this process in a network of higher-order cortical regions, particularly the prefrontal cortex (PFC). Here, we review the circuit mechanisms and functional importance of WM-related activity in these areas. Recent neurophysiological data indicates that the absence of these neural correlates at different stages of WM is accompanied by distinct behavioral deficits, which are characteristic of various disease states/normal aging and which we review here. Finally, we discuss emerging evidence of electrical stimulation ameliorating these WM deficits in both humans and non-human primates. These results are important for a basic understanding of the neural mechanisms supporting WM, as well as for translational efforts to developing therapies capable of enhancing healthy WM ability or restoring WM from dysfunction.
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Affiliation(s)
- Sihai Li
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
| | - Matthew C. Rosen
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
| | - Suha Chang
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
| | - Samuel David
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
| | - David J. Freedman
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
- Neuroscience Institute, The University of Chicago, Chicago, IL, United States
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4
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Gaspar-Silva F, Trigo D, Magalhaes J. Ageing in the brain: mechanisms and rejuvenating strategies. Cell Mol Life Sci 2023; 80:190. [PMID: 37354261 DOI: 10.1007/s00018-023-04832-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/31/2023] [Accepted: 06/07/2023] [Indexed: 06/26/2023]
Abstract
Ageing is characterized by the progressive loss of cellular homeostasis, leading to an overall decline of the organism's fitness. In the brain, ageing is highly associated with cognitive decline and neurodegenerative diseases. With the rise in life expectancy, characterizing the brain ageing process becomes fundamental for developing therapeutic interventions against the increased incidence of age-related neurodegenerative diseases and to aim for an increase in human life span and, more importantly, health span. In this review, we start by introducing the molecular/cellular hallmarks associated with brain ageing and their impact on brain cell populations. Subsequently, we assess emerging evidence on how systemic ageing translates into brain ageing. Finally, we revisit the mainstream and the novel rejuvenating strategies, discussing the most successful ones in delaying brain ageing and related diseases.
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Affiliation(s)
- Filipa Gaspar-Silva
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal
| | - Diogo Trigo
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Joana Magalhaes
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal.
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5
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Castro CCM, Silva SP, Rabelo LN, Queiroz JPG, Campos LD, Silva LC, Fiuza FP. Age, Education Years, and Biochemical Factors Are Associated with Selective Neuronal Changes in the Elderly Hippocampus. Cells 2022; 11:cells11244033. [PMID: 36552799 PMCID: PMC9777473 DOI: 10.3390/cells11244033] [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: 10/14/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022] Open
Abstract
Brain aging involves regional alterations of specific cellular subpopulations in the human hippocampus: a network hub for memory consolidation. The present study investigates whether age, sex, education years, and the concentration of neuropathological and inflammatory proteins influence neuronal-type marker expression in the elderly hippocampus. We analyzed the digital images (1 µm/pixel) of postmortem hippocampal sections from 19 non-demented individuals (from 78 to 99 years). This material was obtained from the "Aging Dementia and TBI Study" open database. Brain samples were processed through in situ hybridization (ISH) for the immunodetection of VGLUT1 (glutamatergic transporter) and GAT1 (GABAergic transporter) and mRNAs and Luminex protein quantifications. After image acquisition, we delineated the dentate gyrus, CA 3/2, and CA1 hippocampal subdivisions. Then, we estimated the area fraction in which the ISH markers were expressed. Increased VGLUT1 was observed in multiple hippocampal subfields at late ages. This glutamatergic marker is positively correlated with beta-amyloid and tau proteins and negatively correlated with interleukin-7 levels. Additionally, education years are positively correlated with GAT1 in the hippocampus of elderly women. This GABAergic marker expression is associated with interferon-gamma and brain-derived neurotrophic factor levels. These associations can help to explain how hippocampal sub-regions and neurotransmitter systems undergo distinct physiological changes during normal aging.
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Cabrera-Moreno J, Jeanson L, Jeschke M, Calapai A. Group-based, autonomous, individualized training and testing of long-tailed macaques ( Macaca fascicularis) in their home enclosure to a visuo-acoustic discrimination task. Front Psychol 2022; 13:1047242. [PMID: 36524199 PMCID: PMC9745322 DOI: 10.3389/fpsyg.2022.1047242] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 11/08/2022] [Indexed: 09/10/2023] Open
Abstract
In recent years, the utility and efficiency of automated procedures for cognitive assessment in psychology and neuroscience have been demonstrated in non-human primates (NHP). This approach mimics conventional shaping principles of breaking down a final desired behavior into smaller components that can be trained in a staircase manner. When combined with home-cage-based approaches, this could lead to a reduction in human workload, enhancement in data quality, and improvement in animal welfare. However, to our knowledge, there are no reported attempts to develop automated training and testing protocols for long-tailed macaques (Macaca fascicularis), a ubiquitous NHP model in neuroscience and pharmaceutical research. In the current work, we present the results from 6 long-tailed macaques that were trained using an automated unsupervised training (AUT) protocol for introducing the animals to the basics of a two-alternative choice (2 AC) task where they had to discriminate a conspecific vocalization from a pure tone relying on images presented on a touchscreen to report their response. We found that animals (1) consistently engaged with the device across several months; (2) interacted in bouts of high engagement; (3) alternated peacefully to interact with the device; and (4) smoothly ascended from step to step in the visually guided section of the procedure, in line with previous results from other NHPs. However, we also found (5) that animals' performance remained at chance level as soon as the acoustically guided steps were reached; and (6) that the engagement level decreased significantly with decreasing performance during the transition from visual to acoustic-guided sections. We conclude that with an autonomous approach, it is possible to train long-tailed macaques in their social group using computer vision techniques and without dietary restriction to solve a visually guided discrimination task but not an acoustically guided task. We provide suggestions on what future attempts could take into consideration to instruct acoustically guided discrimination tasks successfully.
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Affiliation(s)
- Jorge Cabrera-Moreno
- Cognitive Hearing in Primates (CHiP) Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
- Göttingen Graduate School for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate CenterLeibniz-Institute for Primate Research, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Lena Jeanson
- Cognitive Hearing in Primates (CHiP) Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
- Cognitive Neuroscience Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
| | - Marcus Jeschke
- Cognitive Hearing in Primates (CHiP) Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate CenterLeibniz-Institute for Primate Research, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Leibniz-ScienceCampus Primate Cognition, Göttingen, Germany
| | - Antonino Calapai
- Cognitive Hearing in Primates (CHiP) Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate CenterLeibniz-Institute for Primate Research, Göttingen, Germany
- Cognitive Neuroscience Laboratory, German Primate Center, Leibniz-Institute for Primate Research, Göttingen, Germany
- Leibniz-ScienceCampus Primate Cognition, Göttingen, Germany
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7
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Frye BM, Craft S, Register TC, Kim J, Whitlow CT, Barcus RA, Lockhart SN, Sai KKS, Shively CA. Early Alzheimer's disease-like reductions in gray matter and cognitive function with aging in nonhuman primates. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2022; 8:e12284. [PMID: 35310523 PMCID: PMC8918111 DOI: 10.1002/trc2.12284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 12/24/2021] [Accepted: 02/15/2022] [Indexed: 01/13/2023]
Abstract
Introduction Age-related neuropathology associated with sporadic Alzheimer's disease (AD) often develops well before the onset of symptoms. Given AD's long preclinical period, translational models are needed to identify early signatures of pathological decline. Methods Using structural magnetic resonance imaging and cognitive assessments, we examined the relationships among age, cognitive performance, and neuroanatomy in 48 vervet monkeys (Chlorocebus aethiops sabaeus) ranging from young adults to very old. Results We found negative associations of age with cortical gray matter volume (P = .003) and the temporal-parietal cortical thickness meta-region of interest (P = .001). Additionally, cortical gray matter volumes predicted working memory at approximately 1-year follow-up (correct trials at the 20s delay [P = .008]; correct responses after longer delays [P = .004]). Discussion Cortical gray matter diminishes with age in vervets in regions relevant to AD, which may increase risk of cognitive impairment. This study lays the groundwork for future investigations to test therapeutics to delay or slow pathological decline.
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Affiliation(s)
- Brett M. Frye
- Department of Pathology/Comparative MedicineWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Suzanne Craft
- Department of Internal Medicine/GerontologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA,Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA
| | - Thomas C. Register
- Department of Pathology/Comparative MedicineWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA,Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA
| | - Jeongchul Kim
- Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA,Department of RadiologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Christopher T. Whitlow
- Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA,Department of RadiologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Richard A. Barcus
- Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA,Department of RadiologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Samuel N. Lockhart
- Department of Internal Medicine/GerontologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA,Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA
| | - Kiran Kumar Solingapuram Sai
- Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA,Department of RadiologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Carol A. Shively
- Department of Pathology/Comparative MedicineWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA,Wake Forest Alzheimer's Disease Research CenterWinston‐SalemNorth CarolinaUSA
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8
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Ahn K, Lee SJ, Mook-Jung I. White matter-associated microglia: New players in brain aging and neurodegenerative diseases. Ageing Res Rev 2022; 75:101574. [PMID: 35093614 DOI: 10.1016/j.arr.2022.101574] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 12/09/2021] [Accepted: 01/24/2022] [Indexed: 12/20/2022]
Abstract
There has been growing interest in brain aging and rejuvenation. It is well known that brain aging is one of the leading causes of neurodegenerative diseases, such as Alzheimer's disease, but brain aging alone can cause cognitive decline. Microglia are thought to act as 'conductors' of white matter aging by modulating diverse glial cells and phagocytosing white matter-derived myelin debris. A recent study identified a specific subpopulation of microglia in the white matter of aged mice, termed white matter-associated microglia (WAM). Additionally, senescent microglia show impaired phagocytic function and altered lipid metabolism, which cause accumulation of lipid metabolites and eventually lead to myelin sheath degeneration. These results suggest that senescent WAM could be pivotal players in axonal loss during brain aging. The aim of this review is to assess the current state of knowledge on brain aging, with an emphasis on the roles of the white matter and microglia, and suggest potential approaches for rejuvenating the aged brain.
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Affiliation(s)
- Kyusik Ahn
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Republic of Korea
| | - Seung-Jae Lee
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Republic of Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; SNU Dementia Research Center, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Inhee Mook-Jung
- Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Republic of Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; SNU Dementia Research Center, Seoul National University College of Medicine, Seoul 03080, Korea.
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9
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Hernandez CM, Hernandez AR, Hoffman JM, King PH, McMahon LL, Buford TW, Carter C, Bizon JL, Burke SN. A Neuroscience Primer for Integrating Geroscience With the Neurobiology of Aging. J Gerontol A Biol Sci Med Sci 2022; 77:e19-e33. [PMID: 34623396 PMCID: PMC8751809 DOI: 10.1093/gerona/glab301] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Indexed: 11/13/2022] Open
Abstract
Neuroscience has a rich history of studies focusing on neurobiology of aging. However, much of the aging studies in neuroscience occur outside of the gerosciences. The goal of this primer is 2-fold: first, to briefly highlight some of the history of aging neurobiology and second, to introduce to geroscientists the broad spectrum of methodological approaches neuroscientists use to study the neurobiology of aging. This primer is accompanied by a corresponding geroscience primer, as well as a perspective on the current challenges and triumphs of the current divide across these 2 fields. This series of manuscripts is intended to foster enhanced collaborations between neuroscientists and geroscientists with the intent of strengthening the field of cognitive aging through inclusion of parameters from both areas of expertise.
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Affiliation(s)
- Caesar M Hernandez
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Abigail R Hernandez
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jessica M Hoffman
- Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Peter H King
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Neurology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Birmingham Veterans Affairs Medical Center, Birmingham, Alabama, USA
| | - Lori L McMahon
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Nathan Shock Center for the Basic Biology of Aging, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Integrative Center for Aging Research, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Thomas W Buford
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Nathan Shock Center for the Basic Biology of Aging, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Integrative Center for Aging Research, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Geriatric Research Education and Clinical Center, Birmingham VA Medical Center, Birmingham, Alabama, USA
| | - Christy Carter
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Bizon
- Department of Neuroscience, Center for Cognitive Aging and Memory, and the McKnight Brain Institute, The University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Sara N Burke
- Department of Neuroscience, Center for Cognitive Aging and Memory, and the McKnight Brain Institute, The University of Florida, College of Medicine, Gainesville, Florida, USA
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10
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Stonebarger GA, Bimonte-Nelson HA, Urbanski HF. The Rhesus Macaque as a Translational Model for Neurodegeneration and Alzheimer's Disease. Front Aging Neurosci 2021; 13:734173. [PMID: 34539388 PMCID: PMC8446616 DOI: 10.3389/fnagi.2021.734173] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/12/2021] [Indexed: 12/01/2022] Open
Abstract
A major obstacle to progress in understanding the etiology of normative and pathological human brain aging is the availability of suitable animal models for experimentation. The present article will highlight our current knowledge regarding human brain aging and neurodegeneration, specifically in the context of Alzheimer's disease (AD). Additionally, it will examine the use of the rhesus macaque monkey as a pragmatic translational animal model in which to study underlying causal mechanisms. Specifically, the discussion will focus on behavioral and protein-level brain changes that occur within the central nervous system (CNS) of aged monkeys, and compare them to the changes observed in humans during clinically normative aging and in AD.
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Affiliation(s)
- Gail A. Stonebarger
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, United States
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, United States
| | - Heather A. Bimonte-Nelson
- Department of Psychology, Arizona State University, Tempe, AZ, United States
- Arizona Alzheimer’s Consortium, Phoenix, AZ, United States
| | - Henryk F. Urbanski
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, United States
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, United States
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11
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Cuestas Torres DM, Cardenas FP. Synaptic plasticity in Alzheimer's disease and healthy aging. Rev Neurosci 2021; 31:245-268. [PMID: 32250284 DOI: 10.1515/revneuro-2019-0058] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 11/01/2019] [Indexed: 12/17/2022]
Abstract
The strength and efficiency of synaptic connections are affected by the environment or the experience of the individual. This property, called synaptic plasticity, is directly related to memory and learning processes and has been modeled at the cellular level. These types of cellular memory and learning models include specific stimulation protocols that generate a long-term strengthening of the synapses, called long-term potentiation, or a weakening of the said long-term synapses, called long-term depression. Although, for decades, researchers have believed that the main cause of the cognitive deficit that characterizes Alzheimer's disease (AD) and aging was the loss of neurons, the hypothesis of an imbalance in the cellular and molecular mechanisms of synaptic plasticity underlying this deficit is currently widely accepted. An understanding of the molecular and cellular changes underlying the process of synaptic plasticity during the development of AD and aging will direct future studies to specific targets, resulting in the development of much more efficient and specific therapeutic strategies. In this review, we classify, discuss, and describe the main findings related to changes in the neurophysiological mechanisms of synaptic plasticity in excitatory synapses underlying AD and aging. In addition, we suggest possible mechanisms in which aging can become a high-risk factor for the development of AD and how its development could be prevented or slowed.
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Affiliation(s)
- Diana Marcela Cuestas Torres
- Departamento de Psicología and Departamento de Biología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
| | - Fernando P Cardenas
- Departamento de Psicología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
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12
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McQuail JA, Beas BS, Kelly KB, Hernandez CM, Bizon JL, Frazier CJ. Attenuated NMDAR signaling on fast-spiking interneurons in prefrontal cortex contributes to age-related decline of cognitive flexibility. Neuropharmacology 2021; 197:108720. [PMID: 34273386 DOI: 10.1016/j.neuropharm.2021.108720] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 02/01/2023]
Abstract
Ionotropic glutamate receptors of the NMDA and AMPA subtypes transduce excitatory signaling on neurons in the prefrontal cortex (PFC) in support of cognitive flexibility. Cognitive flexibility is reliably observed to decline at advanced ages, coinciding with changes in PFC glutamate receptor expression and neuronal physiology. However, the relationship between age-related impairment of cognitive flexibility and changes to excitatory signaling on distinct classes of PFC neurons is not known. In this study, one cohort of young adult (4 months) and aged (20 months) male F344 rats were characterized for cognitive flexibility on an operant set-shifting task. Expression of the essential NMDAR subunit, NR1, was correlated with individual differences in set-shifting abilities such that lower NR1 in the aged PFC was associated with worse set-shifting. In contrast, lower expression of two AMPAR subunits, GluR1 and GluR2, was not associated with set-shift abilities in aging. As NMDARs are expressed by both pyramidal cells and fast-spiking interneurons (FSI) in PFC, whole-cell patch clamp recordings were performed in a second cohort of age-matched rats to compare age-associated changes on these neuronal subtypes. Evoked excitatory postsynaptic currents were generated using a bipolar stimulator while AMPAR vs. NMDAR-mediated components were isolated using pharmacological tools. The results revealed a clear increase in AMPA/NMDA ratio in FSIs that was not present in pyramidal neurons. Together, these data indicate that loss of NMDARs on interneurons in PFC contributes to age-related impairment of cognitive flexibility.
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Affiliation(s)
- Joseph A McQuail
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.
| | - B Sofia Beas
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, 32610, USA; Unit on the Neurobiology of Affective Memory, National Institute of Mental Health, Bethesda, MD, 20892, USA
| | - Kyle B Kelly
- Department of Pharmacodynamics, University of Florida College of Pharmacy, Gainesville, FL, 32610, USA
| | - Caesar M Hernandez
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, 32610, USA; Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Jennifer L Bizon
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Charles J Frazier
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, 32610, USA; Department of Pharmacodynamics, University of Florida College of Pharmacy, Gainesville, FL, 32610, USA.
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13
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Plagenhoef MR, Callahan PM, Beck WD, Blake DT, Terry AV. Aged rhesus monkeys: Cognitive performance categorizations and preclinical drug testing. Neuropharmacology 2021; 187:108489. [PMID: 33561449 PMCID: PMC8286428 DOI: 10.1016/j.neuropharm.2021.108489] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 12/24/2022]
Abstract
Rodent models have facilitated major discoveries in neurobiology, however, the low success rate of novel medications in clinical trials have led to questions about their translational value in neuropsychiatric drug development research. For age-related disorders of cognition such as Alzheimer' disease (AD) there is interest in moving beyond transgenic amyloid-β and/or tau-expressing rodent models and focusing more on natural aging and dissociating "healthy" from "pathological" aging to identify new therapeutic targets and treatments. In complex disorders such as AD, it can also be argued that animals with closer neurobiology to humans (e.g., nonhuman primates) should be employed more often particularly in the later phases of drug development. The purpose of the work described here was to evaluate the cognitive capabilities of rhesus monkeys across a wide range of ages in different delayed response tasks, a computerized delayed match to sample (DMTS) task and a manual delayed match to position (DMTP) task. Based on specific performance criteria and comparisons to younger subjects, the older subjects were generally less proficient, however, some performed as well as young subjects, while other aged subjects were markedly impaired. Accordingly, the older subjects could be categorized as aged "cognitively-unimpaired" or aged "cognitively-impaired" with a third group (aged-other) falling in between. Finally, as a proof of principle, we demonstrated using the DMTP task that aged cognitively-impaired monkeys are sensitive to the pro-cognitive effects of a nicotinic acetylcholine receptor (nAChR) partial agonist, encenicline, suggesting that nAChR ligands remain viable as potential treatments for age-related disorders of cognition.
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Affiliation(s)
- Marc R Plagenhoef
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia
| | - Patrick M Callahan
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia
| | - Wayne D Beck
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia
| | - David T Blake
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia.
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14
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Stonebarger GA, Urbanski HF, Woltjer RL, Vaughan KL, Ingram DK, Schultz PL, Calderazzo SM, Siedeman JA, Mattison JA, Rosene DL, Kohama SG. Amyloidosis increase is not attenuated by long-term calorie restriction or related to neuron density in the prefrontal cortex of extremely aged rhesus macaques. GeroScience 2020; 42:1733-1749. [PMID: 32876855 PMCID: PMC7732935 DOI: 10.1007/s11357-020-00259-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/24/2020] [Indexed: 01/30/2023] Open
Abstract
As human lifespan increases and the population ages, diseases of aging such as Alzheimer's disease (AD) are a major cause for concern. Although calorie restriction (CR) as an intervention has been shown to increase healthspan in many species, few studies have examined the effects of CR on brain aging in primates. Using postmortem tissue from a cohort of extremely aged rhesus monkeys (22-44 years old, average age 31.8 years) from a longitudinal CR study, we measured immunohistochemically labeled amyloid beta plaques in Brodmann areas 32 and 46 of the prefrontal cortex, areas that play key roles in cognitive processing, are sensitive to aging and, in humans, are also susceptible to AD pathogenesis. We also evaluated these areas for cortical neuron loss, which has not been observed in younger cohorts of aged monkeys. We found a significant increase in plaque density with age, but this was unaffected by diet. Moreover, there was no change in neuron density with age or treatment. These data suggest that even in the oldest-old rhesus macaques, amyloid beta plaques do not lead to overt neuron loss. Hence, the rhesus macaque serves as a pragmatic animal model for normative human aging but is not a complete model of the neurodegeneration of AD. This model of aging may instead prove most useful for determining how even the oldest monkeys are protected from AD, and this information may therefore yield valuable information for clinical AD treatments.
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Affiliation(s)
- G A Stonebarger
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
| | - H F Urbanski
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
| | - R L Woltjer
- Department of Pathology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - K L Vaughan
- Translational Gerontology Branch, National Institute on Aging Intramural Research Program, NIH, Dickerson, MD, 20842, USA
- Charles River, Wilmington, MA, 01867, USA
| | - D K Ingram
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, 70808, USA
| | - P L Schultz
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MD, 02218, USA
| | - S M Calderazzo
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MD, 02218, USA
| | - J A Siedeman
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MD, 02218, USA
| | - J A Mattison
- Translational Gerontology Branch, National Institute on Aging Intramural Research Program, NIH, Dickerson, MD, 20842, USA
| | - D L Rosene
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MD, 02218, USA
| | - S G Kohama
- Division of Neuroscience, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR, 97006, USA.
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15
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Bjorkli C, Sandvig A, Sandvig I. Bridging the Gap Between Fluid Biomarkers for Alzheimer's Disease, Model Systems, and Patients. Front Aging Neurosci 2020; 12:272. [PMID: 32982716 PMCID: PMC7492751 DOI: 10.3389/fnagi.2020.00272] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/06/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is a debilitating neurodegenerative disease characterized by the accumulation of two proteins in fibrillar form: amyloid-β (Aβ) and tau. Despite decades of intensive research, we cannot yet pinpoint the exact cause of the disease or unequivocally determine the exact mechanism(s) underlying its progression. This confounds early diagnosis and treatment of the disease. Cerebrospinal fluid (CSF) biomarkers, which can reveal ongoing biochemical changes in the brain, can help monitor developing AD pathology prior to clinical diagnosis. Here we review preclinical and clinical investigations of commonly used biomarkers in animals and patients with AD, which can bridge translation from model systems into the clinic. The core AD biomarkers have been found to translate well across species, whereas biomarkers of neuroinflammation translate to a lesser extent. Nevertheless, there is no absolute equivalence between biomarkers in human AD patients and those examined in preclinical models in terms of revealing key pathological hallmarks of the disease. In this review, we provide an overview of current but also novel AD biomarkers and how they relate to key constituents of the pathological cascade, highlighting confounding factors and pitfalls in interpretation, and also provide recommendations for standardized procedures during sample collection to enhance the translational validity of preclinical AD models.
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Affiliation(s)
- Christiana Bjorkli
- Sandvig Group, Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Axel Sandvig
- Sandvig Group, Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.,Institute of Neuromedicine and Movement Science, Department of Neurology, St. Olavs Hospital, Trondheim, Norway.,Department of Pharmacology and Clinical Neurosciences, Division of Neuro, Head, and Neck, University Hospital of Umeå, Umeå, Sweden
| | - Ioanna Sandvig
- Sandvig Group, Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
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16
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Damisah EC, Hill RA, Rai A, Chen F, Rothlin CV, Ghosh S, Grutzendler J. Astrocytes and microglia play orchestrated roles and respect phagocytic territories during neuronal corpse removal in vivo. SCIENCE ADVANCES 2020; 6:eaba3239. [PMID: 32637606 PMCID: PMC7319765 DOI: 10.1126/sciadv.aba3239] [Citation(s) in RCA: 157] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 05/12/2020] [Indexed: 05/09/2023]
Abstract
Cell death is prevalent throughout life; however, the coordinated interactions and roles of phagocytes during corpse removal in the live brain are poorly understood. We developed photochemical and viral methodologies to induce death in single cells and combined this with intravital optical imaging. This approach allowed us to track multicellular phagocytic interactions with precise spatiotemporal resolution. Astrocytes and microglia engaged with dying neurons in an orchestrated and synchronized fashion. Each glial cell played specialized roles: Astrocyte processes rapidly polarized and engulfed numerous small dendritic apoptotic bodies, while microglia migrated and engulfed the soma and apical dendrites. The relative involvement and phagocytic specialization of each glial cell was plastic and controlled by the receptor tyrosine kinase Mertk. In aging, there was a marked delay in apoptotic cell removal. Thus, a precisely orchestrated response and cross-talk between glial cells during corpse removal may be critical for maintaining brain homeostasis.
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Affiliation(s)
- Eyiyemisi C. Damisah
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Robert A. Hill
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - Anupama Rai
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Fuyi Chen
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Carla V. Rothlin
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Sourav Ghosh
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Jaime Grutzendler
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, USA
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17
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Isaev NK, Stelmashook EV, Genrikhs EE. Neurogenesis and brain aging. Rev Neurosci 2020; 30:573-580. [PMID: 30763272 DOI: 10.1515/revneuro-2018-0084] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/18/2018] [Indexed: 12/13/2022]
Abstract
Human aging affects the entire organism, but aging of the brain must undoubtedly be different from that of all other organs, as neurons are highly differentiated postmitotic cells, for the majority of which the lifespan in the postnatal period is equal to the lifespan of the entire organism. In this work, we examine the distinctive features of brain aging and neurogenesis during normal aging, pathological aging (Alzheimer's disease), and accelerated aging (Hutchinson-Gilford progeria syndrome and Werner syndrome).
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Affiliation(s)
- Nickolay K Isaev
- M.V. Lomonosov Moscow State University, N.A. Belozersky Institute of Physico-Chemical Biology, Biological Faculty, Moscow 119991, Russia.,Research Center of Neurology, Moscow 125367, Russia
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18
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Low KL, Tomm RJ, Ma C, Tobiansky DJ, Floresco SB, Soma KK. Effects of aging on testosterone and androgen receptors in the mesocorticolimbic system of male rats. Horm Behav 2020; 120:104689. [PMID: 31954104 DOI: 10.1016/j.yhbeh.2020.104689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 11/23/2019] [Accepted: 01/10/2020] [Indexed: 12/18/2022]
Abstract
As males age, systemic testosterone (T) levels decline. T regulates executive function, a collection of cognitive processes that are mediated by the mesocorticolimbic system. Here, we examined young adult (5 months) and aged (22 months) male Fischer 344 × Brown Norway rats, and measured systemic T levels in serum and local T levels in microdissected nodes of the mesocorticolimbic system (ventral tegmental area (VTA), nucleus accumbens (NAc), medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC)). We also measured androgen receptor (AR) immunoreactivity (-ir) in the mesocorticolimbic system. As expected, systemic T levels decreased with age. Local T levels in mesocorticolimbic regions - except the VTA - also decreased with age. Mesocorticolimbic T levels were higher than serum T levels at both ages. AR-ir was present in the VTA, NAc, mPFC, and OFC and decreased with age in the mPFC. Taken together with previous results, the data suggest that changes in androgen signaling may contribute to changes in executive function during aging.
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Affiliation(s)
- Katelyn L Low
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada; Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Ryan J Tomm
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Chunqi Ma
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Daniel J Tobiansky
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Stan B Floresco
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Kiran K Soma
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada; Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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19
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Márquez F, Yassa MA. Neuroimaging Biomarkers for Alzheimer's Disease. Mol Neurodegener 2019; 14:21. [PMID: 31174557 PMCID: PMC6555939 DOI: 10.1186/s13024-019-0325-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 05/28/2019] [Indexed: 12/11/2022] Open
Abstract
Currently, over five million Americans suffer with Alzheimer's disease (AD). In the absence of a cure, this number could increase to 13.8 million by 2050. A critical goal of biomedical research is to establish indicators of AD during the preclinical stage (i.e. biomarkers) allowing for early diagnosis and intervention. Numerous advances have been made in developing biomarkers for AD using neuroimaging approaches. These approaches offer tremendous versatility in terms of targeting distinct age-related and pathophysiological mechanisms such as structural decline (e.g. volumetry, cortical thinning), functional decline (e.g. fMRI activity, network correlations), connectivity decline (e.g. diffusion anisotropy), and pathological aggregates (e.g. amyloid and tau PET). In this review, we survey the state of the literature on neuroimaging approaches to developing novel biomarkers for the amnestic form of AD, with an emphasis on combining approaches into multimodal biomarkers. We also discuss emerging methods including imaging epigenetics, neuroinflammation, and synaptic integrity using PET tracers. Finally, we review the complementary information that neuroimaging biomarkers provide, which highlights the potential utility of composite biomarkers as suitable outcome measures for proof-of-concept clinical trials with experimental therapeutics.
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Affiliation(s)
- Freddie Márquez
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, 92697, USA.
| | - Michael A Yassa
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, 92697, USA.
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20
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Isaev NK, Genrikhs EE, Oborina MV, Stelmashook EV. Accelerated aging and aging process in the brain. Rev Neurosci 2018; 29:233-240. [PMID: 29150992 DOI: 10.1515/revneuro-2017-0051] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022]
Abstract
One of the approaches to the research of the problem of aging is the study of genetic pathologies leading to accelerated aging, such as the Hutchinson-Gilford progeria syndrome, Werner syndrome, and Down syndrome. Probably, this approach can be used in an attempt to understand the neuronal mechanisms underlying normal and pathological brain aging. The analysis of the current state of scientific knowledge about these pathologies shows that in the Hutchinson-Gilford progeria and Werner syndrome, the rate of brain aging is significantly lower than the rate of whole body aging, whereas in Down syndrome, the brain ages faster than other organs due to amyloid-beta accumulation and chronic oxidative stress in the brain tissue. The main point of a previously proposed hypothesis is that the aging of higher animals and humans is associated with an increased level of reactive oxygen species in mitochondria with age, which activates apoptosis, thus reducing the number of functioning cells.
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Affiliation(s)
- Nickolay K Isaev
- Department of Bioenergetics N. A. Belozersky Institute of Physico-Chemical Biology, Biological Faculty, M. V. Lomonosov Moscow State University, 119992 Leninsky Gory, 1b. 40, Moscow 119991, Russia
| | | | - Maria V Oborina
- Brain Research Department Research Center of Neurology, Moscow 125367, Russia
| | - Elena V Stelmashook
- Brain Research Department Research Center of Neurology, Moscow 125367, Russia
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21
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Leone S, Recinella L, Chiavaroli A, Ferrante C, Orlando G, Vacca M, Salvatori R, Brunetti L. Behavioural phenotyping, learning and memory in young and aged growth hormone-releasing hormone-knockout mice. Endocr Connect 2018; 7:924-931. [PMID: 30300535 PMCID: PMC6130317 DOI: 10.1530/ec-18-0165] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Growth hormone-releasing hormone (GHRH) plays an important role in brain functions. The aim of this study was to examine cognitive functions and emotional behaviour in a mouse model of isolated GH deficiency due to bi-allelic ablation of the GHRH gene (GHRH knockout, GHRHKO). METHODS Learning, memory and emotional behaviour were evaluated using a series of validated tests (Morris water maze, eight-arm radial maze, open field, elevated plus maze test, forced swim tests) in 2-, 5- and 12-month-old male mice either homozygous (−/−) or heterozygous (+/−) for the GHRHKO allele. RESULTS Compared with age-matched +/− mice, −/− mice showed decreased cognitive performance in Morris water maze and eight-arm radial maze tests. By comparing the effects of aging in each genotype, we observed an age-related impairment in test results in +/− mice, while in −/− mice a significant decline in cognitive function was found only in 12 months compared with 2-month-old mice, but no difference was found between 5 months old vs 2 months old. −/− mice showed increased exploration activity compared to age-matched +/− controls, while both strains of mice had an age-related decrease in exploration activity. When evaluated through open field, elevated plus maze and forced swim tests, −/− mice demonstrated a decrease in anxiety and depression-related behaviour compared to age-matched +/− controls. CONCLUSIONS Our results suggest that homozygous ablation of GHRH gene is associated with decreased performance in learning and memory tests, possibly linked to increased spontaneous locomotor activity. In addition, we observed an age-related decline in cognitive functions in both genotypes.
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Affiliation(s)
- Sheila Leone
- Department of PharmacyG. d’Annunzio University, Chieti, Italy
| | - Lucia Recinella
- Department of PharmacyG. d’Annunzio University, Chieti, Italy
| | | | | | - Giustino Orlando
- Department of PharmacyG. d’Annunzio University, Chieti, Italy
- Correspondence should be addressed to G Orlando:
| | - Michele Vacca
- Department of PharmacyG. d’Annunzio University, Chieti, Italy
| | - Roberto Salvatori
- Division of EndocrinologyDiabetes and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Luigi Brunetti
- Department of PharmacyG. d’Annunzio University, Chieti, Italy
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22
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Mohan A, Thalamuthu A, Mather KA, Zhang Y, Catts VS, Weickert CS, Sachdev PS. Differential expression of synaptic and interneuron genes in the aging human prefrontal cortex. Neurobiol Aging 2018; 70:194-202. [PMID: 30031232 DOI: 10.1016/j.neurobiolaging.2018.06.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 05/10/2018] [Accepted: 06/07/2018] [Indexed: 02/06/2023]
Abstract
Altered inhibition-excitation balance is implicated in brain aging. We hypothesized that expression of 14 genes encoding proteins localized to synapses or interneurons would show age-related changes relative to 1 another in postmortem tissue from the prefrontal cortex of 37 individuals (18-78 years) and that synaptic or interneuron markers would be differentially correlated with human brain volumes across aging. The majority of genes examined were differentially expressed with age, most being downregulated. Expression of 3 interneuron-related genes was significantly negatively associated with age (calbindin, somatostatin, cholecystokinin), whereas 3 synapse-related genes showed significant age-related expression change (PSD95, GAP43, VGLUT1). On covarying for 2 glial markers (GFAP, IBA1), all 3 interneuron genes and 1 synaptic gene (Growth-associated protein 43) remained significant. Two genes were significantly associated with total brain volume (calbindin, complexin 2) and a marker of synaptic density (synaptophysin) was significantly associated with cortical gray matter volume. Age-related change in expression of genes involved in maintenance of inhibition-excitation balance and regulation of prefrontocortical network dynamics suggests these pathways may contribute to brain aging.
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Affiliation(s)
- Adith Mohan
- Centre for Healthy Brain Ageing (CHeBA), University of New South Wales (UNSW) Australia, Sydney, New South Wales, Australia; School of Psychiatry, UNSW Australia, Sydney, New South Wales, Australia; Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, New South Wales, Australia.
| | - Anbupalam Thalamuthu
- Centre for Healthy Brain Ageing (CHeBA), University of New South Wales (UNSW) Australia, Sydney, New South Wales, Australia
| | - Karen A Mather
- Centre for Healthy Brain Ageing (CHeBA), University of New South Wales (UNSW) Australia, Sydney, New South Wales, Australia
| | - Yiru Zhang
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Vibeke S Catts
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Cynthia Shannon Weickert
- School of Psychiatry, UNSW Australia, Sydney, New South Wales, Australia; Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Perminder S Sachdev
- Centre for Healthy Brain Ageing (CHeBA), University of New South Wales (UNSW) Australia, Sydney, New South Wales, Australia; School of Psychiatry, UNSW Australia, Sydney, New South Wales, Australia; Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, New South Wales, Australia
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23
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Inference of cell type content from human brain transcriptomic datasets illuminates the effects of age, manner of death, dissection, and psychiatric diagnosis. PLoS One 2018; 13:e0200003. [PMID: 30016334 PMCID: PMC6049916 DOI: 10.1371/journal.pone.0200003] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 06/18/2018] [Indexed: 01/01/2023] Open
Abstract
Psychiatric illness is unlikely to arise from pathology occurring uniformly across all cell types in affected brain regions. Despite this, transcriptomic analyses of the human brain have typically been conducted using macro-dissected tissue due to the difficulty of performing single-cell type analyses with donated post-mortem brains. To address this issue statistically, we compiled a database of several thousand transcripts that were specifically-enriched in one of 10 primary cortical cell types in previous publications. Using this database, we predicted the relative cell type content for 833 human cortical samples using microarray or RNA-Seq data from the Pritzker Consortium (GSE92538) or publicly-available databases (GSE53987, GSE21935, GSE21138, CommonMind Consortium). These predictions were generated by averaging normalized expression levels across transcripts specific to each cell type using our R-package BrainInABlender (validated and publicly-released on github). Using this method, we found that the principal components of variation in the datasets strongly correlated with the predicted neuronal/glial content of the samples. This variability was not simply due to dissection–the relative balance of brain cell types appeared to be influenced by a variety of demographic, pre- and post-mortem variables. Prolonged hypoxia around the time of death predicted increased astrocytic and endothelial gene expression, illustrating vascular upregulation. Aging was associated with decreased neuronal gene expression. Red blood cell gene expression was reduced in individuals who died following systemic blood loss. Subjects with Major Depressive Disorder had decreased astrocytic gene expression, mirroring previous morphometric observations. Subjects with Schizophrenia had reduced red blood cell gene expression, resembling the hypofrontality detected in fMRI experiments. Finally, in datasets containing samples with especially variable cell content, we found that controlling for predicted sample cell content while evaluating differential expression improved the detection of previously-identified psychiatric effects. We conclude that accounting for cell type can greatly improve the interpretability of transcriptomic data.
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24
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High-resolution magnetic resonance elastography reveals differences in subcortical gray matter viscoelasticity between young and healthy older adults. Neurobiol Aging 2018; 65:158-167. [PMID: 29494862 PMCID: PMC5883326 DOI: 10.1016/j.neurobiolaging.2018.01.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/10/2018] [Accepted: 01/16/2018] [Indexed: 12/13/2022]
Abstract
Volumetric structural magnetic resonance imaging (MRI) is commonly used to determine the extent of neuronal loss in aging, indicated by cerebral atrophy. The brain, however, exhibits other biophysical characteristics such as mechanical properties, which can be quantified with magnetic resonance elastography (MRE). MRE is an emerging noninvasive imaging technique for measuring viscoelastic tissue properties, proven to be sensitive metrics of neural tissue integrity, as described by shear stiffness, μ and damping ratio, ξ parameters. The study objective was to evaluate global and regional MRE parameter differences between young (19–30 years, n = 12) and healthy older adults (66–73 years, n = 12) and to assess whether MRE measures provide additive value over volumetric magnetic resonance imaging measurements. We investigated the viscoelasticity of the global cerebrum and 6 regions of interest (ROIs) including the amygdala, hippocampus, caudate, pallidum, putamen, and thalamus. In older adults, we found a decrease in μ in all ROIs, except for the hippocampus, indicating widespread brain softening; an effect that remained significant after controlling for ROI volume. In contrast, the relative viscous-to-elastic behavior of the brain ξ did not differ between age groups, suggesting a preservation of the organization of the tissue microstructure. These data support the use of MRE as a novel imaging biomarker for characterizing age-related differences to neural tissue not captured by volumetric imaging alone.
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Transcriptomic profiling of the human brain reveals that altered synaptic gene expression is associated with chronological aging. Sci Rep 2017; 7:16890. [PMID: 29203886 PMCID: PMC5715102 DOI: 10.1038/s41598-017-17322-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/22/2017] [Indexed: 11/23/2022] Open
Abstract
Aging is a biologically universal event, and yet the key events that drive aging are still poorly understood. One approach to generate new hypotheses about aging is to use unbiased methods to look at change across lifespan. Here, we have examined gene expression in the human dorsolateral frontal cortex using RNA- Seq to populate a whole gene co-expression network analysis. We show that modules of co-expressed genes enriched for those encoding synaptic proteins are liable to change with age. We extensively validate these age-dependent changes in gene expression across several datasets including the publically available GTEx resource which demonstrated that gene expression associations with aging vary between brain regions. We also estimated the extent to which changes in cellular composition account for age associations and find that there are independent signals for cellularity and aging. Overall, these results demonstrate that there are robust age-related alterations in gene expression in the human brain and that genes encoding for neuronal synaptic function may be particularly sensitive to the aging process.
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Fiuza FP, Aquino ACQ, Câmara DA, Cavalcanti JRLP, Nascimento Júnior ES, Lima RH, Engelberth RCGJ, Cavalcante JS. Region-specific glial hyperplasia and neuronal stability of rat lateral geniculate nucleus during aging. Exp Gerontol 2017; 100:91-99. [PMID: 29113752 DOI: 10.1016/j.exger.2017.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/20/2017] [Accepted: 11/03/2017] [Indexed: 10/18/2022]
Abstract
The normal aging process is accompanied by functional declines in image-forming and non-image forming visual systems. Among the components of these systems, the thalamic lateral geniculate nucleus (LGN) offers a good model for aging studies since its three anatomical subdivisions, namely dorsal lateral geniculate nucleus (dLGN), intergeniculate leaflet (IGL) and ventral lateral geniculate nucleus (vLGN), receives light information from retina and projects to different brain areas involved in visual-related functions. Nevertheless, there is very little data available about quantitative morphological aspects in LGN across lifespan. In this study, we used design-based stereology to estimate the number of neurons, glial cells, the glia/neuron ratio and the volume of the LGN of Wistar rats from 3, 13 or 23months of age. We examined each LGN subdivision processed by immunohistochemistry for NeuN and Nissl counterstain. We observed no significant age-related neuronal loss in any nuclei and a 21% and 33% significant increase in dLGN and IGL glial cells of 23month-old rats. We also observed the glia/neuron relation increases in dLGN of 13month-old rats and in dLGN, IGL and vLGN internal portion of 23month-old ones. Moreover, we report an age-related increase in IGL volume. These results show region-specific glial hyperplasia during aging within LGN nuclei, perhaps due to compensatory responses to inflammation. In addition, we observed the glia/neuron ratio as a more sensitive parameter to quantify age-related alterations. Hence, we provide an updated and expanded quantitative characterization of these visual-related thalamic nuclei and its variability across lifespan.
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Affiliation(s)
- Felipe P Fiuza
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
| | - Antônio Carlos Q Aquino
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
| | - Diego A Câmara
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
| | - José Rodolfo L P Cavalcanti
- Laboratory of Experimental Neurology, Department of Biomedical Sciences, Health Science Center, University of State of Rio Grande do Norte, 59607-360 Mossoró, RN, Brazil
| | - Expedito S Nascimento Júnior
- Laboratory of Neuroanatomy, Department of Morphology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
| | - Ramon H Lima
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
| | - Rovena Clara G J Engelberth
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
| | - Jeferson S Cavalcante
- Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil
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García-Velázquez L, Arias C. The emerging role of Wnt signaling dysregulation in the understanding and modification of age-associated diseases. Ageing Res Rev 2017. [PMID: 28624530 DOI: 10.1016/j.arr.2017.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Wnt signaling is a highly conserved pathway that participates in multiple aspects of cellular function during development and in adults. In particular, this pathway has been implicated in cell fate determination, proliferation and cell polarity establishment. In the brain, it contributes to synapse formation, axonal remodeling, dendrite outgrowth, synaptic activity, neurogenesis and behavioral plasticity. The expression and distribution of Wnt components in different organs vary with age, which may have important implications for preserving tissue homeostasis. The dysregulation of Wnt signaling has been implicated in age-associated diseases, such as cancer and some neurodegenerative conditions. This is a relevant research topic, as an important research avenue for therapeutic targeting of the Wnt pathway in regenerative medicine has recently been opened. In this review, we discuss the recent findings on the regulation of Wnt components during aging, particularly in brain functioning, and the implications of Wnt signaling in age-related diseases.
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Froudist-Walsh S, López-Barroso D, José Torres-Prioris M, Croxson PL, Berthier ML. Plasticity in the Working Memory System: Life Span Changes and Response to Injury. Neuroscientist 2017; 24:261-276. [PMID: 28691573 DOI: 10.1177/1073858417717210] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Working memory acts as a key bridge between perception, long-term memory, and action. The brain regions, connections, and neurotransmitters that underlie working memory undergo dramatic plastic changes during the life span, and in response to injury. Early life reliance on deep gray matter structures fades during adolescence as increasing reliance on prefrontal and parietal cortex accompanies the development of executive aspects of working memory. The rise and fall of working memory capacity and executive functions parallels the development and loss of neurotransmitter function in frontal cortical areas. Of the affected neurotransmitters, dopamine and acetylcholine modulate excitatory-inhibitory circuits that underlie working memory, are important for plasticity in the system, and are affected following preterm birth and adult brain injury. Pharmacological interventions to promote recovery of working memory abilities have had limited success, but hold promise if used in combination with behavioral training and brain stimulation. The intense study of working memory in a range of species, ages and following injuries has led to better understanding of the intrinsic plasticity mechanisms in the working memory system. The challenge now is to guide these mechanisms to better improve or restore working memory function.
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Affiliation(s)
- Sean Froudist-Walsh
- 1 Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Diana López-Barroso
- 2 Cognitive Neurology and Aphasia Unit and Cathedra ARPA of Aphasia, Centro de Investigaciones Médico-Sanitarias (CIMES) and Instituto de Investigación Biomédica de Malaga, University of Malaga, Malaga, Spain.,3 Area of Psychobiology, Faculty of Psychology, University of Malaga, Malaga, Spain
| | - María José Torres-Prioris
- 2 Cognitive Neurology and Aphasia Unit and Cathedra ARPA of Aphasia, Centro de Investigaciones Médico-Sanitarias (CIMES) and Instituto de Investigación Biomédica de Malaga, University of Malaga, Malaga, Spain.,3 Area of Psychobiology, Faculty of Psychology, University of Malaga, Malaga, Spain
| | - Paula L Croxson
- 1 Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,4 Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marcelo L Berthier
- 2 Cognitive Neurology and Aphasia Unit and Cathedra ARPA of Aphasia, Centro de Investigaciones Médico-Sanitarias (CIMES) and Instituto de Investigación Biomédica de Malaga, University of Malaga, Malaga, Spain
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29
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PROneurotrophins and CONSequences. Mol Neurobiol 2017; 55:2934-2951. [DOI: 10.1007/s12035-017-0505-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/21/2017] [Indexed: 01/12/2023]
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30
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Guha I, Slamova I, Chun S, Clegg A, Golos M, Thrasivoulou C, Simons JP, Al-Shawi R. The effects of short-term JNK inhibition on the survival and growth of aged sympathetic neurons. Neurobiol Aging 2016; 46:138-48. [PMID: 27490965 DOI: 10.1016/j.neurobiolaging.2016.06.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 05/30/2016] [Accepted: 06/24/2016] [Indexed: 11/27/2022]
Abstract
During the course of normal aging, certain populations of nerve growth factor (NGF)-responsive neurons become selectively vulnerable to cell death. Studies using dissociated neurons isolated from neonates have shown that c-Jun N-terminal kinases (JNKs) are important in regulating the survival and neurite outgrowth of NGF-responsive sympathetic neurons. Unlike neonatal neurons, adult sympathetic neurons are not dependent on NGF for their survival. Moreover, the NGF precursor, proNGF, is neurotoxic for aging but not young adult NGF-responsive neurons. Because of these age-related differences, the effects of JNK inhibition on the survival and growth of sympathetic neurons isolated from aged mice were studied. Aged neurons, as well as glia, were found to be dependent on JNK for their growth but not their survival. Conversely, proNGF neurotoxicity was JNK-dependent and mediated by the p75-interacting protein NRAGE, whereas neurite outgrowth was independent of NRAGE. These results have implications for the potential use of JNK inhibitors as therapies for ameliorating age-related neurodegenerative disease.
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Affiliation(s)
- Isa Guha
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK
| | - Ivana Slamova
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK
| | - Soyon Chun
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK
| | - Arthur Clegg
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK
| | - Michal Golos
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK
| | - Chris Thrasivoulou
- Research Department of Cell and Developmental Biology, University College London, London, UK
| | - J Paul Simons
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK.
| | - Raya Al-Shawi
- Genetics Unit and Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, Royal Free Campus, London, UK.
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31
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Febo M, Foster TC. Preclinical Magnetic Resonance Imaging and Spectroscopy Studies of Memory, Aging, and Cognitive Decline. Front Aging Neurosci 2016; 8:158. [PMID: 27468264 PMCID: PMC4942756 DOI: 10.3389/fnagi.2016.00158] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 06/16/2016] [Indexed: 01/14/2023] Open
Abstract
Neuroimaging provides for non-invasive evaluation of brain structure and activity and has been employed to suggest possible mechanisms for cognitive aging in humans. However, these imaging procedures have limits in terms of defining cellular and molecular mechanisms. In contrast, investigations of cognitive aging in animal models have mostly utilized techniques that have offered insight on synaptic, cellular, genetic, and epigenetic mechanisms affecting memory. Studies employing magnetic resonance imaging and spectroscopy (MRI and MRS, respectively) in animal models have emerged as an integrative set of techniques bridging localized cellular/molecular phenomenon and broader in vivo neural network alterations. MRI methods are remarkably suited to longitudinal tracking of cognitive function over extended periods permitting examination of the trajectory of structural or activity related changes. Combined with molecular and electrophysiological tools to selectively drive activity within specific brain regions, recent studies have begun to unlock the meaning of fMRI signals in terms of the role of neural plasticity and types of neural activity that generate the signals. The techniques provide a unique opportunity to causally determine how memory-relevant synaptic activity is processed and how memories may be distributed or reconsolidated over time. The present review summarizes research employing animal MRI and MRS in the study of brain function, structure, and biochemistry, with a particular focus on age-related cognitive decline.
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Affiliation(s)
- Marcelo Febo
- Department of Psychiatry, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
| | - Thomas C Foster
- Department of Neuroscience, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
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32
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Daulatzai MA. Dysfunctional Sensory Modalities, Locus Coeruleus, and Basal Forebrain: Early Determinants that Promote Neuropathogenesis of Cognitive and Memory Decline and Alzheimer’s Disease. Neurotox Res 2016; 30:295-337. [DOI: 10.1007/s12640-016-9643-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 12/22/2022]
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Arey RN, Murphy CT. Conserved regulators of cognitive aging: From worms to humans. Behav Brain Res 2016; 322:299-310. [PMID: 27329151 DOI: 10.1016/j.bbr.2016.06.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/27/2016] [Accepted: 06/17/2016] [Indexed: 01/25/2023]
Abstract
Cognitive decline is a major deficit that arises with age in humans. While some research on the underlying causes of these problems can be done in humans, harnessing the strengths of small model systems, particularly those with well-studied longevity mutants, such as the nematode C. elegans, will accelerate progress. Here we review the approaches being used to study cognitive decline in model organisms and show how simple model systems allow the rapid discovery of conserved molecular mechanisms, which will eventually enable the development of therapeutics to slow cognitive aging.
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Affiliation(s)
- Rachel N Arey
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ 08544, United States
| | - Coleen T Murphy
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ 08544, United States.
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34
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Konar A, Singh P, Thakur MK. Age-associated Cognitive Decline: Insights into Molecular Switches and Recovery Avenues. Aging Dis 2016; 7:121-9. [PMID: 27114845 PMCID: PMC4809604 DOI: 10.14336/ad.2015.1004] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/04/2015] [Indexed: 12/21/2022] Open
Abstract
Age-associated cognitive decline is an inevitable phenomenon that predisposes individuals for neurological and psychiatric disorders eventually affecting the quality of life. Scientists have endeavored to identify the key molecular switches that drive cognitive decline with advancing age. These newly identified molecules are then targeted as recovery of cognitive aging and related disorders. Cognitive decline during aging is multi-factorial and amongst several factors influencing this trajectory, gene expression changes are pivotal. Identifying these genes would elucidate the neurobiological underpinnings as well as offer clues that make certain individuals resilient to withstand the inevitable age-related deteriorations. Our laboratory has focused on this aspect and investigated a wide spectrum of genes involved in crucial brain functions that attribute to senescence induced cognitive deficits. We have recently identified master switches in the epigenome regulating gene expression alteration during brain aging. Interestingly, these factors when manipulated by chemical or genetic strategies successfully reverse the age-related cognitive impairments. In the present article, we review findings from our laboratory and others combined with supporting literary evidences on molecular switches of brain aging and their potential as recovery targets.
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Affiliation(s)
- Arpita Konar
- Department of Zoology, Banaras Hindu University, Varanasi 221005, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Padmanabh Singh
- Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Mahendra K Thakur
- Department of Zoology, Banaras Hindu University, Varanasi 221005, India
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35
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Beas BS, McQuail JA, Ban Uelos C, Setlow B, Bizon JL. Prefrontal cortical GABAergic signaling and impaired behavioral flexibility in aged F344 rats. Neuroscience 2016; 345:274-286. [PMID: 26873002 DOI: 10.1016/j.neuroscience.2016.02.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/03/2016] [Accepted: 02/05/2016] [Indexed: 02/07/2023]
Abstract
The prefrontal cortex (PFC) is critical for the ability to flexibly adapt established patterns of behavior in response to a change in environmental contingencies. Impaired behavioral flexibility results in maladaptive strategies such as perseveration on response options that no longer produce a desired outcome. Pharmacological manipulations of prefrontal cortical GABAergic signaling modulate behavioral flexibility in animal models, and prefrontal cortical interneuron dysfunction is implicated in impaired behavioral flexibility that accompanies neuropsychiatric disease. As deficits in behavioral flexibility also emerge during the normal aging process, the goal of this study was to determine the role of GABAergic signaling, specifically via prefrontal cortical GABA(B) receptors, in such age-related deficits. Young and aged rats were trained in a set shifting task performed in operant chambers. First, rats learned to discriminate between two response levers to obtain a food reward on the basis of a cue light illuminated above the correct lever. Upon acquisition of this initial discrimination, the contingencies were shifted such that rats had to ignore the cue light and respond on the levers according to their left/right positions. Both young and aged rats acquired the initial discrimination similarly; however, aged rats were impaired relative to young following the set shift. Among aged rats, GABA(B) receptor expression in the medial prefrontal cortex (mPFC) was strongly correlated with set shifting, such that lower expression was associated with worse performance. Subsequent experiments showed that intra-mPFC administration of the GABA(B) receptor agonist baclofen enhanced set shifting performance in aged rats. These data directly link GABAergic signaling via GABA(B) receptors to impaired behavioral flexibility associated with normal aging.
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Affiliation(s)
- B S Beas
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States.
| | - J A McQuail
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States.
| | - C Ban Uelos
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States.
| | - B Setlow
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States; Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, United States; Department of Psychology, University of Florida, Gainesville, FL, United States.
| | - J L Bizon
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States; Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, United States.
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McQuail JA, Frazier CJ, Bizon JL. Molecular aspects of age-related cognitive decline: the role of GABA signaling. Trends Mol Med 2015; 21:450-60. [PMID: 26070271 DOI: 10.1016/j.molmed.2015.05.002] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/12/2015] [Accepted: 05/14/2015] [Indexed: 12/19/2022]
Abstract
Alterations in inhibitory interneurons contribute to cognitive deficits associated with several psychiatric and neurological diseases. Phasic and tonic inhibition imparted by γ-aminobutyric acid (GABA) receptors regulates neural activity and helps to establish the appropriate network dynamics in cortical circuits that support normal cognition. This review highlights basic science demonstrating that inhibitory signaling is altered in aging, and discusses the impact of age-related shifts in inhibition on different forms of memory function, including hippocampus-dependent spatial reference memory and prefrontal cortex (PFC)-dependent working memory. The clinical appropriateness and tractability of select therapeutic candidates for cognitive aging that target receptors mediating inhibition are also discussed.
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Affiliation(s)
- Joseph A McQuail
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Charles J Frazier
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA
| | - Jennifer L Bizon
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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37
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Ilieş I, Sîrbulescu RF, Zupanc GK. Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotus leptorhynchus), an organism exhibiting negligible brain senescence. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2014-0109] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The brown ghost knifefish (Apteronotus leptorhynchus (Ellis in Eigenmann, 1912)) is the only vertebrate organism identified thus far that exhibits negligible brain senescence. The present study examines the basic growth patterns of this species, testing the hypothesis that indeterminate growth and lack of reproductive senescence correlate with negligible senescence. Analysis of length–mass relationships revealed negative allometric growth in males and isometric growth in females. Total length at first sexual maturity was 13.5 cm in males and 12.0 cm in females, whereas gonadal mass was 0.02 g in males and 0.2 g in females. Modelling of total length as a function of the number of otolith rings using attenuating growth equations revealed that lengths of up to 26.8 cm in males and 20.2 cm in females can be reached, indicating that the fish continue to grow throughout life. Gonadal mass increased significantly with age in sexually immature individuals of both sexes. In sexually mature fish, gonadal mass showed a marginal increase with age in males and no change in females. The demonstration of indeterminate growth of the fish and of the lack of gonadal regression with age has important implications for the characterization of brown ghost knifefish as a model of negligible senescence.
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Affiliation(s)
- Iulian Ilieş
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Ruxandra F. Sîrbulescu
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Günther K.H. Zupanc
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
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38
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Biology of ageing and role of dietary antioxidants. BIOMED RESEARCH INTERNATIONAL 2014; 2014:831841. [PMID: 24804252 PMCID: PMC3996317 DOI: 10.1155/2014/831841] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 02/12/2014] [Accepted: 02/24/2014] [Indexed: 01/29/2023]
Abstract
Interest in relationship between diet and ageing is growing. Research has shown that dietary calorie restriction and some antioxidants extend lifespan in various ageing models. On the one hand, oxygen is essential to aerobic organisms because it is a final electron acceptor in mitochondria. On the other hand, oxygen is harmful because it can continuously generate reactive oxygen species (ROS), which are believed to be the factors causing ageing of an organism. To remove these ROS in cells, aerobic organisms possess an antioxidant defense system which consists of a series of enzymes, namely, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). In addition, dietary antioxidants including ascorbic acid, vitamin A, vitamin C, α-tocopherol, and plant flavonoids are also able to scavenge ROS in cells and therefore theoretically can extend the lifespan of organisms. In this connection, various antioxidants including tea catechins, theaflavins, apple polyphenols, black rice anthocyanins, and blueberry polyphenols have been shown to be capable of extending the lifespan of fruit flies. The purpose of this review is to brief the literature on modern biological theories of ageing and role of dietary antioxidants in ageing as well as underlying mechanisms by which antioxidants can prolong the lifespan with focus on fruit flies as an model.
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39
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Sale A, Berardi N, Maffei L. Environment and Brain Plasticity: Towards an Endogenous Pharmacotherapy. Physiol Rev 2014; 94:189-234. [DOI: 10.1152/physrev.00036.2012] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Brain plasticity refers to the remarkable property of cerebral neurons to change their structure and function in response to experience, a fundamental theoretical theme in the field of basic research and a major focus for neural rehabilitation following brain disease. While much of the early work on this topic was based on deprivation approaches relying on sensory experience reduction procedures, major advances have been recently obtained using the conceptually opposite paradigm of environmental enrichment, whereby an enhanced stimulation is provided at multiple cognitive, sensory, social, and motor levels. In this survey, we aim to review past and recent work concerning the influence exerted by the environment on brain plasticity processes, with special emphasis on the underlying cellular and molecular mechanisms and starting from experimental work on animal models to move to highly relevant work performed in humans. We will initiate introducing the concept of brain plasticity and describing classic paradigmatic examples to illustrate how changes at the level of neuronal properties can ultimately affect and direct key perceptual and behavioral outputs. Then, we describe the remarkable effects elicited by early stressful conditions, maternal care, and preweaning enrichment on central nervous system development, with a separate section focusing on neurodevelopmental disorders. A specific section is dedicated to the striking ability of environmental enrichment and physical exercise to empower adult brain plasticity. Finally, we analyze in the last section the ever-increasing available knowledge on the effects elicited by enriched living conditions on physiological and pathological aging brain processes.
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Affiliation(s)
- Alessandro Sale
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
| | - Nicoletta Berardi
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
| | - Lamberto Maffei
- Institute of Neuroscience, National Research Council, Pisa, Italy; Department of Psychology, Florence University, Florence, Italy; and Scuola Normale Superiore, Pisa, Italy
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40
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Huang CC, Liu ME, Chou KH, Yang AC, Hung CC, Hong CJ, Tsai SJ, Lin CP. Effect of BDNF Val66Met polymorphism on regional white matter hyperintensities and cognitive function in elderly males without dementia. Psychoneuroendocrinology 2014; 39:94-103. [PMID: 24275008 DOI: 10.1016/j.psyneuen.2013.09.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 09/30/2013] [Accepted: 09/30/2013] [Indexed: 12/26/2022]
Abstract
White matter lesions, also termed White Matter Hyperintensities (WMH), on T2-weighted MR images, are common in the elderly population. Of note, their presence is often accompanied with cognitive decline and the risk of dementia. Even though previous brain ischemia and WM lesion studies have been conducted and indicated that brain-derived neurotrophic factor (BDNF) might protect against neuronal cell death, the interaction between regional WMH volume and the BDNF Val66Met polymorphism on the cognitive performance of healthy elderly population remains unclear. To investigate the genetic effect of BDNF on cognitive function and regional WMH in the healthy elderly population, 90 elderly men, without dementia, with a mean age of 80.6 ± 5.6 y/o were recruited to undergo cognitive tests, structural magnetic resonance imaging (MRI) scans, and genotyping of BDNF alleles. Compared with Met homozygotes, Val homozygotes showed significantly inferior short-term memory (STM) performance (P = .001). A tendency toward dose-dependent effects of the Val allele on WMH volume was found, and Val homozygotes showed larger WMH volume in the temporal (P = .035), the occipital (P = .006), and the global WMH volume (P = .025) than others. Significant interaction effects of BDNF genotypes with temporal WMH volume on STM performance was observed (F1,89 = 4.306, P = .041). Val homozygotes presented steeper negative correlation compared to Met carriers. Mediation analysis also demonstrated that WMH in temporal, limbic, and subcortical regions might mediate the relationship between BDNF's genetic effect and STM performance. Our findings supported the hypothesis that the BDNF Val66Met polymorphism may affect susceptibility to regional WMH volume and such genotype-by-WMH interaction effect is correlated with cognitive decline in non-demented elderly males, in which the Met allele plays a protective role.
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Affiliation(s)
- Chu-Chung Huang
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan; Brain Connectivity Lab, Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Mu-En Liu
- Department of Psychiatry, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Kun-Hsien Chou
- Brain Connectivity Lab, Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taiwan
| | - Albert C Yang
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Center for Dynamical Biomarkers and Translational Medicine, National Central University, Chungli, Taiwan
| | - Chia-Chun Hung
- Brain Connectivity Lab, Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Department of Psychiatry, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Chen-Jee Hong
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Jen Tsai
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
| | - Ching-Po Lin
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan; Brain Connectivity Lab, Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taiwan.
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41
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Samson RD, Barnes CA. Impact of aging brain circuits on cognition. Eur J Neurosci 2013; 37:1903-15. [PMID: 23773059 DOI: 10.1111/ejn.12183] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/05/2013] [Accepted: 02/11/2013] [Indexed: 01/01/2023]
Abstract
Brain networks that engage the hippocampus and prefrontal cortex are central for enabling effective interactions with our environment. Some of the cognitive processes that these structures mediate, such as encoding and retrieving episodic experience, wayfinding, working memory and attention are known to be altered across the lifespan. As illustrated by examples given below, there is remarkable consistency across species in the pattern of age-related neural and cognitive change observed in healthy humans and other animals. These include changes in cognitive operations that are known to be dependent on the hippocampus, as well as those requiring intact prefrontal cortical circuits. Certain cognitive constructs that reflect the function of these areas lend themselves to investigation across species, allowing brain mechanisms at different levels of analysis to be studied in greater depth.
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Affiliation(s)
- Rachel D Samson
- Evelyn F McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
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Traniello IM, Sîrbulescu RF, Ilieş I, Zupanc GKH. Age-related changes in stem cell dynamics, neurogenesis, apoptosis, and gliosis in the adult brain: a novel teleost fish model of negligible senescence. Dev Neurobiol 2013; 74:514-30. [PMID: 24293183 DOI: 10.1002/dneu.22145] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 10/15/2013] [Accepted: 10/29/2013] [Indexed: 11/12/2022]
Abstract
Adult neurogenesis, the generation of new neurons in the adult central nervous system, is a reported feature of all examined vertebrate species. However, a dramatic decline in the rates of cell proliferation and neuronal differentiation occurs in mammals, typically starting near the onset of sexual maturation. In the present study, we examined possible age-related changes associated with adult neurogenesis in the brain of brown ghost knifefish (Apteronotus leptorhynchus), a teleost fish distinguished by its enormous neurogenic potential. Contrary to the well-established alterations in the mammalian brain during aging, in the brain of this teleostean species we could not find evidence for any significant age-related decline in the absolute levels of stem/progenitor cell proliferation, neuronal and glial differentiation, or long-term survival of newly generated cells. Moreover, there was no indication that the amount of glial fibrillary acidic protein or the number of apoptotic cells in the brain was altered significantly over the course of adult life. We hypothesize that this first demonstration of negligible cellular senescence in the vertebrate brain is related to the continued growth of this species and to the lack of reproductive senescence during adulthood. The establishment of the adult brain of this species as a novel model of negligible senescence provides new opportunities for the advancement of our understanding of the biology of aging and the fundamental mechanisms that underlie senescence in the brain.
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Affiliation(s)
- Ian M Traniello
- Laboratory of Neurobiology, Department of Biology, Northeastern University, Boston, Massachusetts, 02115
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Mora F. Successful brain aging: plasticity, environmental enrichment, and lifestyle. DIALOGUES IN CLINICAL NEUROSCIENCE 2013. [PMID: 23576888 PMCID: PMC3622468 DOI: 10.31887/dcns.2013.15.1/fmora] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aging is a physiological process that can develop without the appearance of concurrent diseases. However, very frequently, older people suffer from memory loss and an accelerated cognitive decline. Studies of the neurobiology of aging are beginning to decipher the mechanisms underlying not only the physiology of aging of the brain but also the mechanisms that make people more vulnerable to cognitive dysfunction and neurodegenerative diseases. Today we know that the aging brain retains a considerable functional plasticity, and that this plasticity is positively promoted by genes activated by different lifestyle factors. In this article some of these lifestyle factors and their mechanisms of action are reviewed, including environmental enrichment and the importance of food intake and some nutrients. Aerobic physical exercise and reduction of chronic stress are also briefly reviewed. It is proposed that lifestyle factors are powerful instruments to promote healthy and successful aging of the brain and delay the appearance of age-related cognitive deficits in elderly people.
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Affiliation(s)
- Francisco Mora
- Department of Physiology, Faculty of Medicine, Universidad Complutense, Madrid, Spain.
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44
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Giannaris EL, Rosene DL. A stereological study of the numbers of neurons and glia in the primary visual cortex across the lifespan of male and female rhesus monkeys. J Comp Neurol 2013; 520:3492-508. [PMID: 22430145 DOI: 10.1002/cne.23101] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mild age-related declines in visual function occur in humans and monkeys, independent of ocular pathology, suggesting involvement of central visual pathways (Spear [1993] Vision Res 33:2589-2609). Although many factors might account for this decline, a loss of neurons in primary visual cortex (V1) could be a contributing factor. Previous studies of neuron numbers in V1 reported stability across age, but were limited in the ages and genders studied and sampled only limited parts of V1 or limited cell types, allowing for the possibility of a subtle loss of neurons. We pursued this question in 26 behaviorally tested adult male and female rhesus monkeys ranging from 7.4 to 31.0 years of age by using design-based stereology to estimate numbers of NeuN-labeled neurons and thionin-stained glia within three laminar zones, supragranular (layers II-IVB), granular (IVC), and infragranular (V-VI), across the entirety of V1. There were no significant differences between males and females on any measures, except for total brain weight (P = 0.0038). There was an average of 416,000,000 neurons in V1, but no effect of age on this total or numbers within any laminar zone. Similarly, there was an average of 184,000,000 glia in V1 (44% of the number of neurons), but no effect of age on this total. However, there was a significant age-related increase in numbers of glia in the infragranular zone, perhaps reflecting a glial response to pathology in myelinated projection fibers. This study provides further evidence that in normal aging neurons are not lost and hence cannot account for age-related dysfunction.
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Affiliation(s)
- Eustathia Lela Giannaris
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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45
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Leal SL, Yassa MA. Perturbations of neural circuitry in aging, mild cognitive impairment, and Alzheimer's disease. Ageing Res Rev 2013; 12:823-31. [PMID: 23380151 DOI: 10.1016/j.arr.2013.01.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/17/2013] [Indexed: 01/15/2023]
Abstract
Alzheimer's disease (AD) is a global public health threat that continues to rise as the proportion of the population over the age of 60 rapidly increases. Aging and dementia are both associated with cognitive decline and share some features in terms of structural and functional alterations in neural circuitry. In this review, we attempt to highlight the network perturbations that occur in "typical" aging and emphasize how they may differ from those that manifest in dementia. We focus in particular on neuroimaging studies of the medial temporal lobe (MTL) network, which is involved in episodic memory and is known to change both with age and with AD pathology. We propose a temporal model of structural and functional alterations in the MTL along the aging-dementia continuum. The earliest changes are synaptic in nature and are detectable in particularly vulnerable white matter pathways such as the perforant path. These are followed by structural degradation in the transentorhinal region and subsequently neurodegeneration of the hippocampus as a result of accumulating pathology as well as deafferentation from entorhinal input. We believe that testing this model explicitly is an important direction for future research, particularly in the context of biomarker discovery and clinical trial design.
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Affiliation(s)
- Stephanie L Leal
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
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Callahan PM, Hutchings EJ, Kille NJ, Chapman JM, Terry AV. Positive allosteric modulator of α7 nicotinic-acetylcholine receptors, PNU-120596 augments the effects of donepezil on learning and memory in aged rodents and non-human primates. Neuropharmacology 2013; 67:201-12. [PMID: 23168113 PMCID: PMC3562411 DOI: 10.1016/j.neuropharm.2012.10.019] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/27/2012] [Accepted: 10/31/2012] [Indexed: 01/10/2023]
Abstract
The development of novel therapeutic agents for disorders of cognition such as Alzheimer's disease (AD) is of paramount importance given the ever-increasing elderly population, however; there is also considerable interest in any strategy that might enhance the clinical efficacy of currently available treatments. The purpose of this study was to evaluate an adjunctive treatment strategy to memory enhancement, namely combining the commonly prescribed acetylcholinesterase inhibitor (AChEI) donepezil, with a positive allosteric modulator (PAM) of α7 nicotinic-acetylcholine receptors (α7-nAChRs), PNU-120596. The treatment strategy was evaluated in a (non-spatial) spontaneous novel object recognition (NOR) task in young rats; a water maze spatial learning and recall procedure in aged, cognitively-impaired rats, and a delayed match to sample (working/short term memory) task in aged rhesus monkeys. In all three experiments a similar drug response was observed, namely that donepezil administered alone improved task performance in a dose-dependent manner; that PNU-120596 administered alone was without significant effect, but that the combination of PNU-120596 with a subthreshold dose of donepezil was effective. The positive effect of the drug combination appeared to be α7-nAChR mediated given that it was blocked in the NOR task by the selective α7-nAChR antagonist methyllycaconitine (MLA). Collectively, these data indicate that PNU-120596 increases the effective dose range of donepezil in learning/memory-related tasks in young and age-impaired animal models. The results suggest that α7-nAChR-selective PAMs like PNU-120596 have potential as adjunctive treatments with acetylcholinesterase inhibitors (e.g., donepezil) for age-related illnesses such as AD as well memory disorders not necessarily associated with advanced age.
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Affiliation(s)
- Patrick M. Callahan
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, 30912
- Small Animal Behavior Core, Georgia Health Sciences University, Augusta, Georgia, 30912
| | - Elizabeth J. Hutchings
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, 30912
| | - Nancy J. Kille
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, 30912
| | - James M. Chapman
- Department of Pharmaceutical and Biomedical Sciences, South Carolina College of Pharmacy, Columbia, S.C
| | - Alvin V. Terry
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, 30912
- Small Animal Behavior Core, Georgia Health Sciences University, Augusta, Georgia, 30912
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Isaev NK, Stelmashook EV, Stelmashook NN, Sharonova IN, Skrebitsky VG. Brain aging and mitochondria-targeted plastoquinone antioxidants of SkQ-type. BIOCHEMISTRY (MOSCOW) 2013; 78:295-300. [DOI: 10.1134/s0006297913030127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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48
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A preclinical cognitive test battery to parallel the National Institute of Health Toolbox in humans: bridging the translational gap. Neurobiol Aging 2013; 34:1891-901. [PMID: 23434040 DOI: 10.1016/j.neurobiolaging.2013.01.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 01/01/2023]
Abstract
A major goal of animal research is to identify interventions that can promote successful aging and delay or reverse age-related cognitive decline in humans. Recent advances in standardizing cognitive assessment tools for humans have the potential to bring preclinical work closer to human research in aging and Alzheimer's disease. The National Institute of Health (NIH) has led an initiative to develop a comprehensive Toolbox for Neurologic Behavioral Function (NIH Toolbox) to evaluate cognitive, motor, sensory and emotional function for use in epidemiologic and clinical studies spanning 3 to 85 years of age. This paper aims to analyze the strengths and limitations of animal behavioral tests that can be used to parallel those in the NIH Toolbox. We conclude that there are several paradigms available to define a preclinical battery that parallels the NIH Toolbox. We also suggest areas in which new tests may benefit the development of a comprehensive preclinical test battery for assessment of cognitive function in animal models of aging and Alzheimer's disease.
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49
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Vlassaks E, Gavilanes AWD, Vles JSH, Deville S, Kramer BW, Strackx E, Martinez-Martinez P. The effects of fetal and perinatal asphyxia on neuronal cytokine levels and ceramide metabolism in adulthood. J Neuroimmunol 2012; 255:97-101. [PMID: 23078953 DOI: 10.1016/j.jneuroim.2012.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/15/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
Abstract
In a rat model of global fetal and perinatal asphyxia, we investigated if asphyxia and long-lasting brain tolerance to asphyxia (preconditioning) are mediated by modifications in inflammatory cytokines and ceramide metabolism genes in prefrontal cortex, hippocampus and caudate-putamen at the age of 8months. Most significant changes were found in prefrontal cortex, with reduced LAG1 homolog ceramide synthase 1 expression after both types of asphyxia. Additionally, sphingosine kinase 1 was upregulated in those animals that experienced the combination of fetal and perinatal asphyxia (preconditioning), suggesting increased cell proliferation. While cytokine levels are normal, levels of ceramide genes were modulated both after fetal and perinatal asphyxia in the adult prefrontal cortex. Moreover, the combination of two subsequent asphyctic insults provides long-lasting neuroprotection in the prefrontal cortex probably by maintaining normal apoptosis and promoting cell proliferation. Better understanding of the effects of asphyxia on ceramide metabolism will help to understand the changes leading to brain tolerance and will open opportunities for the development of new neuroprotective therapies.
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Affiliation(s)
- Evi Vlassaks
- Department of Neuropsychology - Division Neuroscience, Maastricht University, School of Mental Health and Neuroscience (MHeNS), Maastricht 6200MD, The Netherlands
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50
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Hara Y, Rapp PR, Morrison JH. Neuronal and morphological bases of cognitive decline in aged rhesus monkeys. AGE (DORDRECHT, NETHERLANDS) 2012; 34:1051-73. [PMID: 21710198 PMCID: PMC3448991 DOI: 10.1007/s11357-011-9278-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 06/03/2011] [Indexed: 05/13/2023]
Abstract
Rhesus monkeys provide a valuable model for studying the basis of cognitive aging because they are vulnerable to age-related decline in executive function and memory in a manner similar to humans. Some of the behavioral tasks sensitive to the effects of aging are the delayed response working memory test, recognition memory tests including the delayed nonmatching-to-sample and the delayed recognition span task, and tests of executive function including reversal learning and conceptual set-shifting task. Much effort has been directed toward discovering the neurobiological parameters that are coupled to individual differences in age-related cognitive decline. Area 46 of the dorsolateral prefrontal cortex (dlPFC) has been extensively studied for its critical role in executive function while the hippocampus and related cortical regions have been a major target of research for memory function. Some of the key age-related changes in area 46 include decreases in volume, microcolumn strength, synapse density, and α1- and α2-adrenergic receptor binding densities. All of these measures significantly correlate with cognitive scores. Interestingly, the critical synaptic subtypes associated with cognitive function appear to be different between the dlPFC and the hippocampus. For example, the dendritic spine subtype most critical to task acquisition and vulnerable to aging in area 46 is the thin spine, whereas in the dentate gyrus, the density of large mushroom spines with perforated synapses correlates with memory performance. This review summarizes age-related changes in anatomical, neuronal, and synaptic parameters within brain areas implicated in cognition and whether these changes are associated with cognitive decline.
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Affiliation(s)
- Yuko Hara
- Fishberg Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, Mount Sinai School of Medicine, New York, NY 10029 USA
- Friedman Brain Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1065, New York, NY 10029 USA
| | - Peter R. Rapp
- Laboratory of Experimental Gerontology, National Institute on Aging, Baltimore, MD 21224 USA
| | - John H. Morrison
- Fishberg Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, Mount Sinai School of Medicine, New York, NY 10029 USA
- Friedman Brain Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1065, New York, NY 10029 USA
- Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, NY 10029 USA
- Computational Neurobiology and Imaging Center, Mount Sinai School of Medicine, New York, NY 10029 USA
- Department of Neuroscience, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1065, New York, NY 10029 USA
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