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Lyu J, Nagarajan R, Kambali M, Wang M, Rudolph U. Selective inhibition of somatostatin-positive dentate hilar interneurons induces age-related cellular changes and cognitive dysfunction. PNAS NEXUS 2023; 2:pgad134. [PMID: 37168673 PMCID: PMC10165806 DOI: 10.1093/pnasnexus/pgad134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/19/2023] [Accepted: 04/04/2023] [Indexed: 05/13/2023]
Abstract
The cellular basis of age-related impairments of hippocampal function is not fully understood. In order to evaluate the role of somatostatin-positive (Sst+) interneurons in the dentate gyrus (DG) hilus in this process, we chemogenetically inhibited Sst+ interneurons in the DG hilus. Chronic chemogenetic inhibition (CCI) of these neurons resulted in increased c-Fos staining in the DG hilus, a decrease in the percentage of GAD67- and of Sst-expressing interneurons in the DG, and increased microglial activation in DG, CA3, and CA1. Total dendritic length and spine density were reduced in DG and CA1, suggesting reduced dendritic complexity. Behaviorally, the recognition index in an object recognition task and the percentage of spontaneous alternations in the Y-maze were decreased, while in both initial and reversal learning in the Morris water maze, the latencies to find the hidden platform were increased, suggesting cognitive dysfunction. Our findings establish a causal role for a reduced function of Sst+ interneurons in the DG hilus for cognitive decline and suggest that this reduced function may contribute to age-related impairments of learning and memory. Furthermore, our CCI mice may represent a cellularly defined model of hippocampal aging.
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Affiliation(s)
- Jinrui Lyu
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
- Neuroscience Program, College of Liberal Arts and Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
| | - Rajasekar Nagarajan
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
| | - Maltesh Kambali
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
| | - Muxiao Wang
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
- Neuroscience Program, College of Liberal Arts and Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802-6178, USA
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2
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Gradwell MA, Smith KM, Dayas CV, Smith DW, Hughes DI, Callister RJ, Graham BA. Altered Intrinsic Properties and Inhibitory Connectivity in Aged Parvalbumin-Expressing Dorsal Horn Neurons. Front Neural Circuits 2022; 16:834173. [PMID: 35874431 PMCID: PMC9305305 DOI: 10.3389/fncir.2022.834173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 06/15/2022] [Indexed: 11/13/2022] Open
Abstract
The incidence of pain symptoms such as allodynia are known to increase with age. Parvalbumin expressing interneurons (PVINs) within the dorsal horn (DH) of the spinal cord play an important role in allodynia whereby their inhibitory connections prevent innocuous touch information from exciting nociceptive pathways. Here we ask whether the functional properties of PVINs are altered by aging, comparing their functional properties in adult (3–7 month) and aged mice (23–28 month). Patch clamp recordings were made from PVINs in laminae IIi-III of parasagittal spinal cord slices. The intrinsic excitability of PVINs changed with age. Specifically, AP discharge shifted from initial bursting to tonic firing, and firing duration during current injection increased. The nature of excitatory synaptic input to PVINs also changed with age with larger but less frequent spontaneous excitatory currents occurring in aged mice, however, the net effect of these differences produced a similar level of overall excitatory drive. Inhibitory drive was also remarkably similar in adult and aged PVINs. Photostimulation of ChR2 expressing PVINs was used to study inhibitory connections between PVINs and unidentified DH neurons and other PVINs. Based on latency and jitter, monosynaptic PVIN to unidentified-cell and PVIN-PVIN connections were compared in adult and aged mice, showing that PVIN to unidentified-cell connection strength increased with age. Fitting single or double exponentials to the decay phase of IPSCs showed there was also a shift from mixed (glycinergic and GABAergic) to GABAergic inhibitory transmission in aged animals. Overall, our data suggest the properties of PVIN neurons in aged animals enhance their output in spinal circuits in a manner that would blunt allodynia and help maintain normal sensory experience during aging.
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Affiliation(s)
- Mark A. Gradwell
- Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Kelly M. Smith
- Centre for Neuroscience, Science Tower, University of Pittsburgh, Pittsburgh, PA, United States
| | - Christopher V. Dayas
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
- Brain Neuromodulation Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - Douglas W. Smith
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
- Brain Neuromodulation Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - David I. Hughes
- Institute of Neuroscience Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Robert J. Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
- Brain Neuromodulation Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - Brett A. Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
- Brain Neuromodulation Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
- *Correspondence: Brett A. Graham,
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3
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Wirak GS, Florman J, Alkema MJ, Connor CW, Gabel CV. Age-associated changes to neuronal dynamics involve a disruption of excitatory/inhibitory balance in C. elegans. eLife 2022; 11:72135. [PMID: 35703498 PMCID: PMC9273219 DOI: 10.7554/elife.72135] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
In the aging brain, many of the alterations underlying cognitive and behavioral decline remain opaque. C. elegans offers a powerful model for aging research, with a simple, well-studied nervous system to further our understanding of the cellular modifications and functional alterations accompanying senescence. We perform multi-neuronal functional imaging across the aged C. elegans nervous system, measuring an age-associated breakdown in system-wide functional organization. At single-cell resolution, we detect shifts in activity dynamics toward higher frequencies. In addition, we measure a specific loss of inhibitory signaling that occurs early in the aging process and alters the systems critical excitatory/inhibitory balance. These effects are recapitulated with mutation of the calcium channel subunit UNC-2/CaV2a. We find that manipulation of inhibitory GABA signaling can partially ameliorate or accelerate the effects of aging. The effects of aging are also partially mitigated by disruption of the insulin signaling pathway, known to increase longevity, or by a reduction of caspase activation. Data from mammals are consistent with our findings, suggesting a conserved shift in the balance of excitatory/inhibitory signaling with age that leads to breakdown in global neuronal dynamics and functional decline.
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Affiliation(s)
- Gregory S Wirak
- Department of Physiology and Biophysics, Boston University, Boston, United States
| | - Jeremy Florman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Mark J Alkema
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Christopher W Connor
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, United States
| | - Christopher V Gabel
- Department of Physiology and Biophysics, Boston University, Boston, United States
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4
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Hernandez CM, McQuail JA, Ten Eyck TW, Wheeler AR, Labiste CC, Setlow B, Bizon J. GABA B receptors in prelimbic cortex and basolateral amygdala differentially influence intertemporal decision making and decline with age. Neuropharmacology 2022; 209:109001. [PMID: 35189132 DOI: 10.1016/j.neuropharm.2022.109001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/07/2022] [Accepted: 02/15/2022] [Indexed: 11/25/2022]
Abstract
The ability to decide adaptively between immediate vs. delayed gratification (intertemporal choice) is critical for well-being and is associated with a range of factors that influence quality of life. In contrast to young adults, many older adults show enhanced preference for delayed gratification; however, the neural mechanisms underlying this age difference in intertemporal choice are largely un-studied. Changes in signaling through GABAB receptors (GABABRs) mediate several age-associated differences in cognitive processes linked to intertemporal choice. The current study used a rat model to determine how GABABRs in two brain regions known to regulate intertemporal choice (prelimbic cortex; PrL and basolateral amygdala; BLA) contribute to age differences in this form of decision making in male rats. As in humans, aged rats showed enhanced preference for large, delayed over small, immediate rewards during performance in an intertemporal choice task in operant test chambers. Activation of PrL GABABRs via microinfusion of the agonist baclofen increased choice of large, delayed rewards in young adult rats but did not influence choice in aged rats. Conversely, infusion of baclofen into the BLA strongly reduced choice of large, delayed rewards in both young adult and aged rats. Aged rats further showed a significant reduction in expression of GABABR1 subunit isoforms in the prefrontal cortex, a discovery that is consonant with the null effect of intra-PrL baclofen on intertemporal choice in aged rats. In contrast, expression of GABABR subunits was generally conserved with age in the BLA. Jointly, these findings elucidate a role for GABABRs in intertemporal choice and identify fundamental features of brain maturation and aging that mediate an improved ability to delay gratification.
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Affiliation(s)
- Caesar M Hernandez
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA; Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA; McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Joseph A McQuail
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA; Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine - Columbia, Columbia, SC, 29208, USA
| | - Tyler W Ten Eyck
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - Alexa-Rae Wheeler
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - Chase C Labiste
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.
| | - Barry Setlow
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA; Department of Psychiatry, University of Florida, Gainesville, FL, 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Jennifer 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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5
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Gramuntell Y, Klimczak P, Coviello S, Perez-Rando M, Nacher J. Effects of Aging on the Structure and Expression of NMDA Receptors of Somatostatin Expressing Neurons in the Mouse Hippocampus. Front Aging Neurosci 2022; 13:782737. [PMID: 35002680 PMCID: PMC8733323 DOI: 10.3389/fnagi.2021.782737] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Changes in the physiology, neurochemistry and structure of neurons, particularly of their dendritic spines, are thought to be crucial players in age-related cognitive decline. One of the most studied brain structures affected by aging is the hippocampus, known to be involved in different essential cognitive processes. While the aging-associated quantitative changes in dendritic spines of hippocampal pyramidal cells have already been studied, the relationship between aging and the structural dynamics of hippocampal interneurons remains relatively unknown. Spines are not a frequent feature in cortical inhibitory neurons, but these postsynaptic structures are abundant in a subpopulation of somatostatin expressing interneurons, particularly in oriens-lacunosum moleculare (O-LM) cells in the hippocampal CA1. Previous studies from our laboratory have shown that the spines of these interneurons are highly plastic and influenced by NMDA receptor manipulation. Thus, in the present study, we have investigated the impact of aging on this interneuronal subpopulation. The analyses were performed in 3−, 9−, and 16-month-old GIN mice, a strain in which somatostatin positive interneurons express GFP. We studied the changes in the density of dendritic spines, en passant boutons, and the expression of NMDA receptors (GluN1 and GluN2B) using confocal microscopy and image analysis. We observed a significant decrease in dendritic spine density in 9-month-old animals when compared with 3-month-old animals. We also observed a decrease in the expression of the GluN2B subunit in O-LM cells, but not of that of GluN1, during aging. These results will constitute the basis for more advanced studies of the structure and connectivity of interneurons during aging and their contribution to cognitive decline.
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Affiliation(s)
- Yaiza Gramuntell
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Patrycja Klimczak
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain.,Spanish National Network for Research in Mental Health, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Simona Coviello
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Marta Perez-Rando
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain.,Spanish National Network for Research in Mental Health, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.,Fundación Investigación Hospital Clínico de Valencia, INCLIVA, Valencia, Spain
| | - Juan Nacher
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain.,Spanish National Network for Research in Mental Health, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.,Fundación Investigación Hospital Clínico de Valencia, INCLIVA, Valencia, Spain
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6
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The aging mouse brain: cognition, connectivity and calcium. Cell Calcium 2021; 94:102358. [PMID: 33517250 DOI: 10.1016/j.ceca.2021.102358] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/16/2021] [Accepted: 01/18/2021] [Indexed: 02/08/2023]
Abstract
Aging is a complex process that differentially impacts multiple cognitive, sensory, neuronal and molecular processes. Technological innovations now allow for parallel investigation of neuronal circuit function, structure and molecular composition in the brain of awake behaving adult mice. Thus, mice have become a critical tool to better understand how aging impacts the brain. However, a more granular systems-based approach, which considers the impact of age on key features relating to neural processing, is required. Here, we review evidence probing the impact of age on the mouse brain. We focus on a range of processes relating to neuronal function, including cognitive abilities, sensory systems, synaptic plasticity and calcium regulation. Across many systems, we find evidence for prominent age-related dysregulation even before 12 months of age, suggesting that emerging age-related alterations can manifest by late adulthood. However, we also find reports suggesting that some processes are remarkably resilient to aging. The evidence suggests that aging does not drive a parallel, linear dysregulation of all systems, but instead impacts some processes earlier, and more severely, than others. We propose that capturing the more fine-scale emerging features of age-related vulnerability and resilience may provide better opportunities for the rejuvenation of the aged brain.
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7
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Popescu IR, Le KQ, Ducote AL, Li JE, Leland AE, Mostany R. Increased intrinsic excitability and decreased synaptic inhibition in aged somatosensory cortex pyramidal neurons. Neurobiol Aging 2020; 98:88-98. [PMID: 33249377 DOI: 10.1016/j.neurobiolaging.2020.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/02/2020] [Accepted: 10/08/2020] [Indexed: 10/23/2022]
Abstract
Sensorimotor performance declines during advanced age, partially due to deficits in somatosensory acuity. Cortical receptive field expansion contributes to somatosensory deficits, suggesting increased excitability or decreased inhibition in primary somatosensory cortex (S1) pyramidal neurons. To ascertain changes in excitability and inhibition, we measured both properties in neurons from vibrissal S1 in brain slices from young and aged mice. Because adapting and non-adapting neurons-the principal pyramidal types in layer 5 (L5)-differ in intrinsic properties and inhibitory inputs, we determined age-dependent changes according to neuron type. We found an age-dependent increase in intrinsic excitability in adapting neurons, caused by a decrease in action potential threshold. Surprisingly, in non-adapting neurons we found both an increase in excitability caused by increased input resistance, and a decrease in synaptic inhibition. Spike frequency adaptation, already small in non-adapting neurons, was further reduced by aging, whereas sag, a manifestation of Ih, was increased. Therefore, aging caused both decreased inhibition and increased intrinsic excitability, but these effects were specific to pyramidal neuron type.
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Affiliation(s)
- Ion R Popescu
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA.
| | - Kathy Q Le
- Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Alexis L Ducote
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Jennifer E Li
- Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | | | - Ricardo Mostany
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
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8
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Francavilla R, Guet-McCreight A, Amalyan S, Hui CW, Topolnik D, Michaud F, Marino B, Tremblay MÈ, Skinner FK, Topolnik L. Alterations in Intrinsic and Synaptic Properties of Hippocampal CA1 VIP Interneurons During Aging. Front Cell Neurosci 2020; 14:554405. [PMID: 33173468 PMCID: PMC7591401 DOI: 10.3389/fncel.2020.554405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/10/2020] [Indexed: 12/21/2022] Open
Abstract
Learning and memory deficits are hallmarks of the aging brain, with cortical neuronal circuits representing the main target in cognitive deterioration. While GABAergic inhibitory and disinhibitory circuits are critical in supporting cognitive processes, their roles in age-related cognitive decline remain largely unknown. Here, we examined the morphological and physiological properties of the hippocampal CA1 vasoactive intestinal peptide/calretinin-expressing (VIP+/CR+) type 3 interneuron-specific (I-S3) cells across mouse lifespan. Our data showed that while the number and morphological features of I-S3 cells remained unchanged, their firing and synaptic properties were significantly altered in old animals. In particular, the action potential duration and the level of steady-state depolarization were significantly increased in old animals in parallel with a significant decrease in the maximal firing frequency. Reducing the fast-delayed rectifier potassium or transient sodium conductances in I-S3 cell computational models could reproduce the age-related changes in I-S3 cell firing properties. However, experimental data revealed no difference in the activation properties of the Kv3.1 and A-type potassium currents, indicating that transient sodium together with other ion conductances may be responsible for the observed phenomena. Furthermore, I-S3 cells in aged mice received a stronger inhibitory drive due to concomitant increase in the amplitude and frequency of spontaneous inhibitory currents. These age-associated changes in the I-S3 cell properties occurred in parallel with an increased inhibition of their target interneurons and were associated with spatial memory deficits and increased anxiety. Taken together, these data indicate that VIP+/CR+ interneurons responsible for local circuit disinhibition survive during aging but exhibit significantly altered physiological properties, which may result in the increased inhibition of hippocampal interneurons and distorted mnemonic functions.
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Affiliation(s)
- Ruggiero Francavilla
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Alexandre Guet-McCreight
- Krembil Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Sona Amalyan
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Chin Wai Hui
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Dimitry Topolnik
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Félix Michaud
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Beatrice Marino
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
- Department of Molecular Medicine, Faculty of Medicine, Université Laval, Québec, QC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Frances K. Skinner
- Krembil Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, ON, Canada
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
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9
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Cisneros-Franco JM, Voss P, Thomas ME, de Villers-Sidani E. Critical periods of brain development. HANDBOOK OF CLINICAL NEUROLOGY 2020; 173:75-88. [PMID: 32958196 DOI: 10.1016/b978-0-444-64150-2.00009-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Brain plasticity is maximal at specific time windows during early development known as critical periods (CPs), during which sensory experience is necessary to establish optimal cortical representations of the surrounding environment. After CP closure, a range of functional and structural elements prevent passive experience from eliciting significant plastic changes in the brain. The transition from a plastic to a more fixed state is advantageous as it allows for the sequential consolidation and retention of new and more complex perceptual, motor, and cognitive functions. However, the formation of stable neural representations may pose limitations on future revisions to the circuitry. If sensory experience is abnormal or absent during this time, it can have profound effects on sensory representations in adulthood, resulting in quasi-permanent adaptations that can make it nearly impossible to learn certain skills or process certain stimulus properties later on in life. This chapter begins with a brief introduction to experience-dependent plasticity throughout the lifespan (Section Introduction). Next, we define what constitutes a CP (Section What Are Critical Periods?) and review some of the key CPs in the visual and auditory systems (Section Key Critical Periods of Sensory Systems). We then discuss the mechanisms whereby cortical plasticity is regulated both locally and through neuromodulatory systems (Section How Are Critical Periods Regulated?). Finally, we highlight studies showing that CPs can be extended beyond their normal epochs, closed prematurely, or reopened during adult life by merely altering sensory inputs (Section Timing of Critical Periods: Can CP Plasticity Be Extended, Limited, or Reactivated?).
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Affiliation(s)
- J Miguel Cisneros-Franco
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Patrice Voss
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Maryse E Thomas
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Etienne de Villers-Sidani
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada.
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10
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Rozycka A, Charzynska A, Misiewicz Z, Maciej Stepniewski T, Sobolewska A, Kossut M, Liguz-Lecznar M. Glutamate, GABA, and Presynaptic Markers Involved in Neurotransmission Are Differently Affected by Age in Distinct Mouse Brain Regions. ACS Chem Neurosci 2019; 10:4449-4461. [PMID: 31556991 DOI: 10.1021/acschemneuro.9b00220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Molecular synaptic aging perturbs neurotransmission and decreases the potential for neuroplasticity. The direction and degree of changes observed in aging are often region or cell specific, hampering the generalization of age-related effects. Using real-time PCR and Western blot analyses, we investigated age-related changes in several presynaptic markers (Vglut1, Vglut2, Gad65, Gad67, Vgat, synaptophysin) involved in the initial steps of glutamatergic and GABAergic neurotransmission, in several cortical regions, in young (3-4 months old), middle-aged (1 year old), and old (2 years old) mice. We found age-related changes mainly in protein levels while, apart from the occipital cortex, virtually no significant changes in mRNA levels were detected, which suggests that aging acts on the investigated markers mainly through post-transcriptional mechanisms depending on the brain region. Principal component analysis (PCA) of protein data revealed that each brain region possessed a type of "biochemical distinctiveness" (each analyzed brain region was best characterized by higher variability level of a particular synaptic marker) that was lost with age. Analysis of glutamate and γ-aminobutyric acid (GABA) levels in aging suggested that mechanisms keeping an overall balance between the two amino acids in the brain are weakened in the hippocampus. Our results unravel the differences in mRNA/protein interactions in the aging brain.
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Affiliation(s)
- Aleksandra Rozycka
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Agata Charzynska
- Laboratory of Bioinformatics, Neurobiology Center, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur Str., 02-093 Warsaw, Poland
| | - Zuzanna Misiewicz
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
- Molecular and Integrative Biosciences Research Program, University of Helsinki, Helsinki FI-00014, Finland
| | - Tomasz Maciej Stepniewski
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
- Research Programme on Biomedical Informatics (GRIB) - Department of Experimental and Health Sciences, Hospital del Mar Medical Research Institute, Pompeu Fabra University, 08002 Barcelona, Spain
| | - Alicja Sobolewska
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Str., 02-957 Warsaw, Poland
| | - Malgorzata Kossut
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
- Faculty of Psychology, SWPS University of Social Sciences and Humanities, 03-815 Warsaw, Poland
| | - Monika Liguz-Lecznar
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
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Bonfiglio T, Vergassola M, Olivero G, Pittaluga A. Environmental Training and Synaptic Functions in Young and Old Brain: A Presynaptic Perspective. Curr Med Chem 2019; 26:3670-3684. [PMID: 29493441 DOI: 10.2174/0929867325666180228170450] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Aging is an unavoidable, physiological process that reduces the complexity and the plasticity of the synaptic contacts in Central Nervous System (CNS), having profound implications for human well-being. The term "cognitive reserve" refers to central cellular adaptations that augment the resilience of human brain to damage and aging. The term "Cognitive training" indicates the cultural, social and physical stimulations proposed as add-on therapy for the cure of central neurological diseases. "Cognitive training" reinforces the "cognitive reserve" permitting to counteract brain impairments and rejuvenating synaptic complexity. The research has begun investigating the clinical impact of the "cognitive training" in aged people, but additional work is needed to definitively assess its effectiveness. In particular, there is a need to understand, from a preclinical point of view, whether "cognitive training" promotes compensatory effects or, alternatively, if it elicits genuine recovery of neuronal defects. Although the translation from rodent studies to the clinical situation could be difficult, the results from pre-clinical models are of high clinical relevance, since they should allow a better understanding of the effects of environmental interventions in aging-associated chronic derangements in mammals. CONCLUSION Data in literature and the recent results obtained in our laboratory concerning the impact of environmental stimulation on the presynaptic release of noradrenaline, glutamate and gamma amino butyric acid (GABA) suggest that these neurotransmitters undergo different adaptations during aging and that they are differently tuned by "cognitive training". The impact of "cognitive training" on neurotransmitter exocytosis might account for the cellular events involved in reinforcement of "cognitive reserve" in young and old animals.
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Affiliation(s)
- Tommaso Bonfiglio
- Department of Pharmacy, DIFAR, University of Genoa, Viale Cembrano 4, 16148 Genoa, Italy
| | - Matteo Vergassola
- Department of Pharmacy, DIFAR, University of Genoa, Viale Cembrano 4, 16148 Genoa, Italy
| | - Guendalina Olivero
- Department of Pharmacy, DIFAR, University of Genoa, Viale Cembrano 4, 16148 Genoa, Italy
| | - Anna Pittaluga
- Department of Pharmacy, DIFAR, University of Genoa, Viale Cembrano 4, 16148 Genoa, Italy.,Center of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV, 16132 Genoa, Italy
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12
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GABA A Receptors Are Well Preserved in the Hippocampus of Aged Mice. eNeuro 2019; 6:ENEURO.0496-18.2019. [PMID: 31340951 PMCID: PMC6709233 DOI: 10.1523/eneuro.0496-18.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 07/02/2019] [Accepted: 07/15/2019] [Indexed: 01/04/2023] Open
Abstract
GABA is the primary inhibitory neurotransmitter in the nervous system. GABAA receptors (GABAARs) are pentameric ionotropic channels. Subunit composition of the receptors is associated with the affinity of GABA binding and its downstream inhibitory actions. Fluctuations in subunit expression levels with increasing age have been demonstrated in animal and human studies. However, our knowledge regarding the age-related hippocampal GABAAR expression changes is limited and based on rat studies. This study is the first analysis of the aging-related changes of the GABAAR subunit expression in the CA1, CA2/3, and dentate gyrus regions of the mouse hippocampus. Using Western blotting and immunohistochemistry we found that the GABAergic system is robust, with no significant age-related differences in GABAAR α1, α2, α3, α5, β3, and γ2 subunit expression level differences found between the young (6 months) and old (21 months) age groups in any of the hippocampal regions examined. However, we detected a localized decrease of α2 subunit expression around the soma, proximal dendrites, and in the axon initial segment of pyramidal cells in the CA1 and CA3 regions that is accompanied by a pronounced upregulation of the α2 subunit immunoreactivity in the neuropil of aged mice. In summary, GABAARs are well preserved in the mouse hippocampus during normal aging although GABAARs in the hippocampus are severely affected in age-related neurological disorders, including Alzheimer’s disease.
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13
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Gao T, Liu Y, Zhao Z, Luo Y, Wang L, Wang Y, Yin Y. L-655,708 Does not Prevent Isoflurane-induced Memory Deficits in Old Mice. Transl Neurosci 2019; 10:180-186. [PMID: 31410301 PMCID: PMC6689210 DOI: 10.1515/tnsci-2019-0032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/21/2019] [Indexed: 01/07/2023] Open
Abstract
Background General anesthesia and increasing age are two main risk factors for postoperative cognitive dysfunction (POCD). Effective agents for the prevention or treatment of POCD are urgently needed. L-655,708, an inverse agonist of α5 subunit-containing γ-aminobutyric acid subtype A (α5GABAA) receptors, can prevent anesthesia-induced memory deficits in young animals. However, there is a lack of evidence of its efficacy in old animals. Methodology Young (3- to 5-month-old) and old (18- to 20-month-old) mice were given an inhalation of 1.33% isoflurane for 1 hour and their associative memory was evaluated 24 hours after anesthesia using fear-conditioning tests (FCTs). To evaluate the effect of L-655,708, mice received intraperitoneal injections of L-655,708 (0.7 mg/kg) or vehicle 30 minutes before anesthesia. Results Old mice exhibited impaired memory and lower hippocampal α5GABAA levels than young mice under physiological conditions. Pre-injections of L-655,708 significantly alleviated isoflurane-induced memory decline in young mice, but not in old mice. Conclusions L-655,708 is not as effective for the prevention of POCD in old mice as it is in young mice. The use of inverse agonists of α5GABAA in preventing POCD in old patients should be carefully considered.
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Affiliation(s)
- Teng Gao
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, 100038, China
| | - Yue Liu
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Zifang Zhao
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Yuan Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Lifang Wang
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Yiqing Yin
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
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14
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Cisplatin treatment induces attention deficits and impairs synaptic integrity in the prefrontal cortex in mice. Sci Rep 2018; 8:17400. [PMID: 30479361 PMCID: PMC6258730 DOI: 10.1038/s41598-018-35919-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/08/2018] [Indexed: 12/15/2022] Open
Abstract
Patients treated for cancer frequently experience chemobrain, characterized by impaired memory and reduced attention. These deficits often persist after treatment, and no preventive or curative interventions exist. In mice, we assessed the effect of cisplatin chemotherapy on attention using the 5-choice serial reaction time task and on synaptic integrity. We also assessed the capacity of mesenchymal stem cells to normalize the characteristics of chemobrain. Mice were trained in the 5-choice serial reaction time task. After reaching advancement criteria at a 4-second stimulus time, they were treated with cisplatin followed by nasal administration of mesenchymal stem cells. Cisplatin reduced the percentage of correct responses due to an increase in omissions, indicating attention deficits. Mesenchymal stem cell treatment reversed these cisplatin-induced deficits in attention. Cisplatin also induced abnormalities in markers of synaptic integrity in the prefrontal cortex. Specifically, cisplatin decreased expression of the global presynaptic marker synaptophysin and the glutamatergic presynaptic marker vGlut2. Expression of the presynaptic GABAergic marker vGAT increased. Nasal mesenchymal stem cell administration normalized these markers of synaptic integrity. In conclusion, cisplatin induces long-lasting attention deficits that are associated with decreased synaptic integrity in the prefrontal cortex. Nasal administration of mesenchymal stem cells reversed these behavioural and structural deficits.
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15
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Stover KR, Lim S, Zhou TL, Stafford PM, Chow J, Li H, Sivanenthiran N, Mylvaganam S, Wu C, Weaver DF, Eubanks J, Zhang L. Susceptibility to hippocampal kindling seizures is increased in aging C57 black mice. IBRO Rep 2017; 3:33-44. [PMID: 30135940 PMCID: PMC6084868 DOI: 10.1016/j.ibror.2017.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 08/19/2017] [Accepted: 08/20/2017] [Indexed: 11/23/2022] Open
Abstract
The incidence of seizures increases with old age. Stroke, dementia and brain tumors are recognized risk factors for new-onset seizures in the aging populations and the incidence of these conditions also increased with age. Whether aging is associated with higher seizure susceptibility in the absence of the above pathologies remains unclear. We used classic kindling to explore this issue as the kindling model is highly reproducible and allows close monitoring of electrographic and motor seizure activities in individual animals. We kindled male young and aging mice (C57BL/6 strain, 2-3 and 18-22 months of age) via daily hippocampal CA3 stimulation and monitored seizure activity via video and electroencephalographic recordings. The aging mice needed fewer stimuli to evoke stage-5 motor seizures and exhibited longer hippocampal afterdischarges and more frequent hippocampal spikes relative to the young mice, but afterdischarge thresholds and cumulative afterdischarge durations to stage 5 motor seizures were not different between the two age groups. While hippocampal injury and structural alterations at cellular and micro-circuitry levels remain to be examined in the kindled mice, our present observations suggest that susceptibility to hippocampal CA3 kindling seizures is increased with aging in male C57 black mice.
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Affiliation(s)
- Kurt R. Stover
- Krembil Research Institute, University Health Network, Canada
| | - Stellar Lim
- Krembil Research Institute, University Health Network, Canada
| | - Terri-Lin Zhou
- Krembil Research Institute, University Health Network, Canada
| | | | - Jonathan Chow
- Krembil Research Institute, University Health Network, Canada
| | - Haoyuan Li
- Krembil Research Institute, University Health Network, Canada
| | | | | | - Chiping Wu
- Krembil Research Institute, University Health Network, Canada
| | - Donald F. Weaver
- Krembil Research Institute, University Health Network, Canada
- Departments of Chemistry, University of Toronto, Canada
- Departments of Medicine, University of Toronto, Canada
| | - James Eubanks
- Krembil Research Institute, University Health Network, Canada
- Departments of Surgery, University of Toronto, Canada
- University of Toronto Epilepsy Program, Canada
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Canada
- Departments of Medicine, University of Toronto, Canada
- University of Toronto Epilepsy Program, Canada
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16
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Apland JP, Aroniadou-Anderjaska V, Figueiredo TH, Prager EM, Olsen CH, Braga MFM. Susceptibility to Soman Toxicity and Efficacy of LY293558 Against Soman-Induced Seizures and Neuropathology in 10-Month-Old Male Rats. Neurotox Res 2017; 32:694-706. [PMID: 28776308 DOI: 10.1007/s12640-017-9789-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/13/2017] [Accepted: 07/21/2017] [Indexed: 12/23/2022]
Abstract
Acute nerve agent exposure causes prolonged status epilepticus (SE), leading to death or long-term brain damage. We have previously demonstrated that LY293558, an AMPA/GluK1 kainate receptor antagonist, terminates SE induced by the nerve agent soman and protects from long-term brain damage, in immature rats and young-adult rats, even if administered with a relatively long latency from the time of exposure. However, susceptibility to the lethal consequences of SE increases with age, and mortality by SE induced by soman is substantially greater in older animals. Therefore, in the present study, we compared the susceptibility to soman toxicity of 10-month-old male rats with that of young-adult male rats (42 to 50 days old) and examined the protective efficacy of LY293558 in the older group. A lower percentage of the 10-month-old rats developed SE after injection of 1.2 × LD50 soman, compared to the young adults, the latency to seizure onset was longer in the older rats, and seizure intensity did not differ between the two age groups. However, mortality rate in the older rats who developed SE was higher than in the young adults. Acetylcholinesterase activity in the amygdala, hippocampus, and piriform cortex did not differ between the two age groups. Administration of LY293558 at 20 or 60 min post-exposure suppressed SE, increased 24-h survival rate, decreased the long-term risk of death, reduced neuronal degeneration in the amygdala, hippocampus, piriform, and entorhinal cortices, and facilitated recovery from body weight loss. Thus, LY293558 is an effective countermeasure against soman toxicity also in older animals.
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Affiliation(s)
- James P Apland
- Neuroscience Program, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Aberdeen, MD, 21010, USA
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Eric M Prager
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,John Wiley and Sons, Inc., 111 River Street, Hoboken, NJ, 07030, USA
| | - Cara H Olsen
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA. .,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
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17
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Rozycka A, Liguz-Lecznar M. The space where aging acts: focus on the GABAergic synapse. Aging Cell 2017; 16:634-643. [PMID: 28497576 PMCID: PMC5506442 DOI: 10.1111/acel.12605] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2017] [Indexed: 12/19/2022] Open
Abstract
As it was established that aging is not associated with massive neuronal loss, as was believed in the mid‐20th Century, scientific interest has addressed the influence of aging on particular neuronal subpopulations and their synaptic contacts, which constitute the substrate for neural plasticity. Inhibitory neurons represent the most complex and diverse group of neurons, showing distinct molecular and physiological characteristics and possessing a compelling ability to control the physiology of neural circuits. This review focuses on the aging of GABAergic neurons and synapses. Understanding how aging affects synapses of particular neuronal subpopulations may help explain the heterogeneity of aging‐related effects. We reviewed the literature concerning the effects of aging on the numbers of GABAergic neurons and synapses as well as aging‐related alterations in their presynaptic and postsynaptic components. Finally, we discussed the influence of those changes on the plasticity of the GABAergic system, highlighting our results concerning aging in mouse somatosensory cortex and linking them to plasticity impairments and brain disorders. We posit that aging‐induced impairments of the GABAergic system lead to an inhibitory/excitatory imbalance, thereby decreasing neuron's ability to respond with plastic changes to environmental and cellular challenges, leaving the brain more vulnerable to cognitive decline and damage by synaptopathic diseases.
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Affiliation(s)
- Aleksandra Rozycka
- Department of Molecular and Cellular Neurobiology; Nencki Institute of Experimental Biology; Polish Academy of Sciences; 3 Pasteur Street Warsaw 02-093 Poland
| | - Monika Liguz-Lecznar
- Department of Molecular and Cellular Neurobiology; Nencki Institute of Experimental Biology; Polish Academy of Sciences; 3 Pasteur Street Warsaw 02-093 Poland
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18
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Villanueva-Castillo C, Tecuatl C, Herrera-López G, Galván EJ. Aging-related impairments of hippocampal mossy fibers synapses on CA3 pyramidal cells. Neurobiol Aging 2016; 49:119-137. [PMID: 27794263 DOI: 10.1016/j.neurobiolaging.2016.09.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 11/16/2022]
Abstract
The network interaction between the dentate gyrus and area CA3 of the hippocampus is responsible for pattern separation, a process that underlies the formation of new memories, and which is naturally diminished in the aged brain. At the cellular level, aging is accompanied by a progression of biochemical modifications that ultimately affects its ability to generate and consolidate long-term potentiation. Although the synapse between dentate gyrus via the mossy fibers (MFs) onto CA3 neurons has been subject of extensive studies, the question of how aging affects the MF-CA3 synapse is still unsolved. Extracellular and whole-cell recordings from acute hippocampal slices of aged Wistar rats (34 ± 2 months old) show that aging is accompanied by a reduction in the interneuron-mediated inhibitory mechanisms of area CA3. Several MF-mediated forms of short-term plasticity, MF long-term potentiation and at least one of the critical signaling cascades necessary for potentiation are also compromised in the aged brain. An analysis of the spontaneous glutamatergic and gamma-aminobutyric acid-mediated currents on CA3 cells reveal a dramatic alteration in amplitude and frequency of the nonevoked events. CA3 cells also exhibited increased intrinsic excitability. Together, these results demonstrate that aging is accompanied by a decrease in the GABAergic inhibition, reduced expression of short- and long-term forms of synaptic plasticity, and increased intrinsic excitability.
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Affiliation(s)
| | - Carolina Tecuatl
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México
| | | | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México.
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19
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Clark R, Blizzard C, Dickson T. Inhibitory dysfunction in amyotrophic lateral sclerosis: future therapeutic opportunities. Neurodegener Dis Manag 2015; 5:511-25. [DOI: 10.2217/nmt.15.49] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In amyotrophic lateral sclerosis, motor neuron hyperexcitability and inhibitory dysfunction is emerging as a potential causative link in the dysfunction and degeneration of the motoneuronal circuitry that characterizes the disease. Interneurons, as key regulators of excitability, may mediate much of this imbalance, yet we know little about the way in which inhibitory deficits perturb excitability. In this review, we explore inhibitory control of excitability and the potential contribution of altered inhibition to amyotrophic lateral sclerosis disease processes and vulnerabilities, identifying important windows of therapeutic opportunity and potential interventions, specifically targeting inhibitory control at key disease stages.
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Affiliation(s)
- Rosemary Clark
- Menzies Institute for Medical Research, University of Tasmania, Hobart TAS 7000, Australia
| | - Catherine Blizzard
- Menzies Institute for Medical Research, University of Tasmania, Hobart TAS 7000, Australia
| | - Tracey Dickson
- Menzies Institute for Medical Research, University of Tasmania, Hobart TAS 7000, Australia
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20
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Region-specific reduction of auditory sensory gating in older adults. Brain Cogn 2015; 101:64-72. [DOI: 10.1016/j.bandc.2015.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/13/2015] [Accepted: 10/16/2015] [Indexed: 11/21/2022]
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21
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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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22
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Kouvaros S, Kotzadimitriou D, Papatheodoropoulos C. Hippocampal sharp waves and ripples: Effects of aging and modulation by NMDA receptors and L-type Ca2+ channels. Neuroscience 2015; 298:26-41. [PMID: 25869622 DOI: 10.1016/j.neuroscience.2015.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/02/2015] [Accepted: 04/06/2015] [Indexed: 12/19/2022]
Abstract
Aging is accompanied by a complicated pattern of changes in the brain organization and often by alterations in specific memory functions. One of the brain activities with important role in the process of memory consolidation is thought to be the hippocampus activity of sharp waves and ripple oscillation (SWRs). Using field recordings from the CA1 area of hippocampal slices we compared SWRs as well as single pyramidal cell activity between adult (3-6-month old) and old (24-34-month old) Wistar rats. The slices from old rats displayed ripple oscillation with a significantly less number of ripples and lower frequency compared with those from adult animals. However, the hippocampus from old rats had significantly higher propensity to organized SWRs in long sequences. Furthermore, the bursts recorded from complex spike cells in slices from old compared with adult rats displayed higher number of spikes and longer mean inter-spike interval. Blockade of N-methyl-D-aspartic acid (NMDA) receptors by 3-((R)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) increased the amplitude of both sharp waves and ripples and increased the interval between events of SWRs in both age groups. On the contrary, CPP reduced the probability of occurrence of sequences of SWRs more strongly in slices from adult than old rats. Blockade of L-type voltage-dependent calcium channels by nifedipine only enhanced the amplitude of sharp waves in slices from adult rats. CPP increased the postsynaptic excitability and the paired-pulse inhibition in slices from both adult and old rats similarly while nifedipine increased the postsynaptic excitability only in slices from adult rats. We propose that the tendency of the aged hippocampus to generate long sequences of SWR events might represent the consequence of homeostatic mechanisms that adaptively try to compensate the impairment in the ripple oscillation in order to maintain the behavioral outcome efficient in the old individuals. The age-dependent alterations in the firing mode of pyramidal cells might underlie to some extent the changes in ripples that occur in old animals.
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Affiliation(s)
- S Kouvaros
- Laboratory of Physiology, Department of Medicine, University of Patras, 26504 Rion, Greece
| | - D Kotzadimitriou
- Laboratory of Physiology, Department of Medicine, University of Patras, 26504 Rion, Greece
| | - C Papatheodoropoulos
- Laboratory of Physiology, Department of Medicine, University of Patras, 26504 Rion, Greece.
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23
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Cardoso A, Silva D, Magano S, Pereira PA, Andrade JP. Old-onset caloric restriction effects on neuropeptide Y- and somatostatin-containing neurons and on cholinergic varicosities in the rat hippocampal formation. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9737. [PMID: 25471895 PMCID: PMC4259091 DOI: 10.1007/s11357-014-9737-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 11/25/2014] [Indexed: 06/04/2023]
Abstract
Caloric restriction is able to delay age-related neurodegenerative diseases and cognitive impairment. In this study, we analyzed the effects of old-onset caloric restriction that started at 18 months of age, in the number of neuropeptide Y (NPY)- and somatostatin (SS)-containing neurons of the hippocampal formation. Knowing that these neuropeptidergic systems seem to be dependent of the cholinergic system, we also analyzed the number of cholinergic varicosities. Animals with 6 months of age (adult controls) and with 18 months of age were used. The animals aged 18 months were randomly assigned to controls or to caloric-restricted groups. Adult and old control rats were maintained in the ad libitum regimen during 6 months. Caloric-restricted rats were fed, during 6 months, with 60 % of the amount of food consumed by controls. We found that aging induced a reduction of the total number of NPY- and SS-positive neurons in the hippocampal formation accompanied by a decrease of the cholinergic varicosities. Conversely, the 24-month-old-onset caloric-restricted animals maintained the number of those peptidergic neurons and the density of the cholinergic varicosities similar to the 12-month control rats. These results suggest that the aging-associated reduction of these neuropeptide-expressing neurons is not due to neuronal loss and may be dependent of the cholinergic system. More importantly, caloric restriction has beneficial effects in the NPY- and SS-expressing neurons and in the cholinergic system, even when applied in old age.
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Affiliation(s)
- Armando Cardoso
- Department of Anatomy, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal,
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Intracellular activities related to in vitro hippocampal sharp waves are altered in CA3 pyramidal neurons of aged mice. Neuroscience 2014; 277:474-85. [PMID: 25088916 DOI: 10.1016/j.neuroscience.2014.07.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 07/09/2014] [Accepted: 07/09/2014] [Indexed: 01/11/2023]
Abstract
Pyramidal neurons in the hippocampal CA3 area interconnect intensively via recurrent axonal collaterals, and such CA3-to-CA3 recurrent circuitry plays important roles in the generation of hippocampal network activities. In particular, the CA3 circuitry is able to generate spontaneous sharp waves (SPWs) when examined in vitro. These in vitro SPWs are thought to result from the network activity of GABAergic inhibitory interneurons as SPW-correlating intracellular activities are featured with strong IPSPs in pyramidal neurons and EPSPs or spikes in GABAergic interneurons. In view of accumulating evidence indicating a decrease in subgroups of hippocampal GABAergic interneurons in aged animals, we test the hypothesis that the intracellular activities related to in vitro SPWs are altered in CA3 pyramidal neurons of aged mice. Hippocampal slices were prepared from adult and aged C57 black mice (ages 3-6 and 24-28months respectively). Population and single-cell activities were examined via extracellular and whole-cell patch-clamp recordings. CA3 SPW frequencies were not significantly different between the slices of adult and aged mice but SPW-correlating intracellular activities featured weaker IPSC components in aged CA3 pyramidal neurons compared to adult neurons. It was unlikely that this latter phenomenon was due to general impairments of GABAergic synapses in the aged CA3 circuitry as evoked IPSC responses and pharmacologically isolated IPSCs were observed in aged CA3 pyramidal neurons. In addition, aged CA3 pyramidal neurons displayed more positive resting potentials and had a higher propensity of burst firing than adult neurons. We postulate that alterations of GABAergic network activity may explain the reduced IPCS contributions to in vitro SPWs in aged CA3 pyramidal neurons. Overall, our present observations are supportive of the notion that excitability of hippocampal CA3 circuitry is increased in aged mice.
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Talaei SA, Salami M. Sensory experience differentially underlies developmental alterations of LTP in CA1 area and dentate gyrus. Brain Res 2013; 1537:1-8. [DOI: 10.1016/j.brainres.2013.08.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/31/2013] [Accepted: 08/30/2013] [Indexed: 11/28/2022]
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Griffith WH, Dubois DW, Fincher A, Peebles KA, Bizon JL, Murchison D. Characterization of age-related changes in synaptic transmission onto F344 rat basal forebrain cholinergic neurons using a reduced synaptic preparation. J Neurophysiol 2013; 111:273-86. [PMID: 24133226 DOI: 10.1152/jn.00129.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Basal forebrain (BF) cholinergic neurons participate in a number of cognitive processes that become impaired during aging. We previously found that age-related enhancement of Ca(2+) buffering in rat cholinergic BF neurons was associated with impaired performance in the water maze spatial learning task (Murchison D, McDermott AN, Lasarge CL, Peebles KA, Bizon JL, and Griffith WH. J Neurophysiol 102: 2194-2207, 2009). One way that altered Ca(2+) buffering could contribute to cognitive impairment involves synaptic function. In this report we show that synaptic transmission in the BF is altered with age and cognitive status. We have examined the properties of spontaneous postsynaptic currents (sPSCs) in cholinergic BF neurons that have been mechanically dissociated without enzymes from behaviorally characterized F344 rats. These isolated neurons retain functional presynaptic terminals on their somata and proximal dendrites. Using whole cell patch-clamp recording, we show that sPSCs and miniature PSCs are predominately GABAergic (bicuculline sensitive) and in all ways closely resemble PSCs recorded in a BF in vitro slice preparation. Adult (4-7 mo) and aged (22-24 mo) male rats were cognitively assessed using the water maze. Neuronal phenotype was identified post hoc using single-cell RT-PCR. The frequency of sPSCs was reduced during aging, and this was most pronounced in cognitively impaired subjects. This is the same population that demonstrated increased intracellular Ca(2+) buffering. We also show that increasing Ca(2+) buffering in the synaptic terminals of young BF neurons can mimic the reduced frequency of sPSCs observed in aged BF neurons.
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Affiliation(s)
- William H Griffith
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science Center, Bryan, Texas; and
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Kanak DJ, Rose GM, Zaveri HP, Patrylo PR. Altered network timing in the CA3-CA1 circuit of hippocampal slices from aged mice. PLoS One 2013; 8:e61364. [PMID: 23593474 PMCID: PMC3620228 DOI: 10.1371/journal.pone.0061364] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 03/07/2013] [Indexed: 01/05/2023] Open
Abstract
Network patterns are believed to provide unique temporal contexts for coordinating neuronal activity within and across different regions of the brain. Some of the characteristics of network patterns modeled in vitro are altered in the CA3 or CA1 subregions of hippocampal slices from aged mice. CA3-CA1 network interactions have not been examined previously. We used slices from aged and adult mice to model spontaneous sharp wave ripples and carbachol-induced gamma oscillations, and compared measures of CA3-CA1 network timing between age groups. Coherent sharp wave ripples and gamma oscillations were evident in the CA3-CA1 circuit in both age groups, but the relative timing of activity in CA1 stratum pyramidale was delayed in the aged. In another sample of aged slices, evoked Schaffer collateral responses were attenuated in CA3 (antidromic spike amplitude) and CA1 (orthodromic field EPSP slope). However, the amplitude and timing of spontaneous sharp waves recorded in CA1 stratum radiatum were similar to adults. In both age groups unit activity recorded juxtacellularly from unidentified neurons in CA1 stratum pyramidale and stratum oriens was temporally modulated by CA3 ripples. However, aged neurons exhibited reduced spike probability during the early cycles of the CA3 ripple oscillation. These findings suggest that aging disrupts the coordination of patterned activity in the CA3-CA1 circuit.
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Affiliation(s)
- Daniel J Kanak
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois, United States of America.
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28
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Hippocampal excitability is increased in aged mice. Exp Neurol 2013; 247:710-9. [PMID: 23510762 DOI: 10.1016/j.expneurol.2013.03.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/05/2013] [Accepted: 03/08/2013] [Indexed: 12/22/2022]
Abstract
Aging is known to be associated with a high risk of developing seizure disorders. Currently, the mechanisms underlying this increased seizure susceptibility are not fully understood. Several previous studies have shown a loss of subgroups of GABAergic inhibitory interneurons in the hippocampus of aged rodents, yet the network excitability intrinsic to the aged hippocampus remains to be elucidated. The aim of this study is to examine age-dependent changes of hippocampal network activities in young adult (3-5 months), aging (16-18 months), and aged (24-28 months) mice. We conducted intracranial electroencephalographic (EEG) recordings in free-moving animals and extracellular recordings in hippocampal slices in vitro. EEG recordings revealed frequent spikes in aging and aged mice but only occasionally in young adults. These EEG spikes were suppressed following diazepam administration. Spontaneous field potentials with large amplitudes were frequently observed in hippocampal slices of aged mice but rarely in slices from young adults. These spontaneous field potentials originated from the CA3 area and their generation was dependent upon the excitatory glutamatergic activity. We therefore postulate that hippocampal network excitability is increased in aged mice and that such hyperactivity may be relevant to the increased seizure susceptibility observed in aged subjects.
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Liu Q, Huang Y, Shen J, Steffensen S, Wu J. Functional α7β2 nicotinic acetylcholine receptors expressed in hippocampal interneurons exhibit high sensitivity to pathological level of amyloid β peptides. BMC Neurosci 2012; 13:155. [PMID: 23272676 PMCID: PMC3573893 DOI: 10.1186/1471-2202-13-155] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 12/18/2012] [Indexed: 11/10/2022] Open
Abstract
Background β-amyloid (Aβ) accumulation is described as a hallmark of Alzheimer’s disease (AD). Aβ perturbs a number of synaptic components including nicotinic acetylcholine receptors containing α7 subunits (α7-nAChRs), which are abundantly expressed in the hippocampus and found on GABAergic interneurons. We have previously demonstrated the existence of a novel, heteromeric α7β2-nAChR in basal forebrain cholinergic neurons that exhibits high sensitivity to acute Aβ exposure. To extend our previous work, we evaluated the expression and pharmacology of α7β2-nAChRs in hippocampal interneurons and their sensitivity to Aβ. Results GABAergic interneurons in the CA1 subregion of the hippocampus expressed functional α7β2-nAChRs, which were characterized by relatively slow whole-cell current kinetics, pharmacological sensitivity to dihydro-β-erythroidine (DHβE), a nAChR β2* subunit selective blocker, and α7 and β2 subunit interaction using immunoprecipitation assay. In addition, α7β2-nAChRs were sensitive to 1 nM oligomeric Aβ. Similar effects were observed in identified hippocampal interneurons prepared from GFP-GAD mice. Conclusion These findings suggest that Aβ modulation of cholinergic signaling in hippocampal GABAergic interneurons via α7β2-nAChRs could be an early and critical event in Aβ-induced functional abnormalities of hippocampal function, which may be relevant to learning and memory deficits in AD.
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Affiliation(s)
- Qiang Liu
- Divisions of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA
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Morley BJ, Mervis RF. Dendritic spine alterations in the hippocampus and parietal cortex of alpha7 nicotinic acetylcholine receptor knockout mice. Neuroscience 2012; 233:54-63. [PMID: 23270857 DOI: 10.1016/j.neuroscience.2012.12.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 12/19/2022]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is involved in higher cognitive and memory functions, and is associated with the etiology of neurological diseases involving cognitive decline, including Alzheimer's disease (AD). We hypothesized that spine changes in the α7 knockout might help to explain the behavioral deficits observed in α7 knockout mice and prodromal hippocampal changes in AD. We quantified several measures of dendritic morphology in the CA1 region of the mouse hippocampus in Golgi-stained material from wildtype and α7 knockout mice at P24. The most significant difference was a 64% increase in thin (L-type) dendritic spines on the CA1 basilar tree in knockout mice (p<.05). There were small decreases in the number of in N-type (-15%), M-type (-14%) and D-type (-4%) spine densities. The CA1 basilar dendritic tree of knockout mice had significantly less branching in the regions near the soma in comparison with wildtype animals (p<.01), but not in the more distal branching. Changes in the configuration of CA1 basilar dendritic spines have been observed in a number of experimental paradigms, suggesting that basilar dendritic spines are highly plastic. One component of cognitive dysfunction may be through α7-modulated GABAergic interneurons synapsing on CA1 basal dendrites.
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Affiliation(s)
- B J Morley
- Boys Town National Research Hospital, 555 North 30th Street, Omaha, NE 68131, USA.
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31
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Erbs E, Faget L, Scherrer G, Kessler P, Hentsch D, Vonesch JL, Matifas A, Kieffer BL, Massotte D. Distribution of delta opioid receptor-expressing neurons in the mouse hippocampus. Neuroscience 2012; 221:203-13. [PMID: 22750239 DOI: 10.1016/j.neuroscience.2012.06.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 06/08/2012] [Accepted: 06/09/2012] [Indexed: 10/28/2022]
Abstract
Delta opioid receptors participate to the control of chronic pain and emotional responses. Recent data also identified their implication in spatial memory and drug-context associations pointing to a critical role of hippocampal delta receptors. We examined the distribution of delta receptor-expressing cells in the hippocampus using fluorescent knock-in mice that express a functional delta receptor fused at its carboxyterminus with the green fluorescent protein in place of the native receptor. Colocalization with markers for different neuronal populations was performed by immunohistochemical detection. Fine mapping in the dorsal hippocampus confirmed that delta opioid receptors are mainly present in GABAergic neurons. Indeed, they are mostly expressed in parvalbumin-immunopositive neurons both in the Ammon's horn and dentate gyrus. These receptors, therefore, most likely participate in the dynamic regulation of hippocampal activity.
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Affiliation(s)
- E Erbs
- Department of Human Genetics and Translational Medicine, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM/UdS, 1 Rue Laurent Fries, F-67404 Illkirch-Graffenstaden, France
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Villette V, Poindessous-Jazat F, Bellessort B, Roullot E, Peterschmitt Y, Epelbaum J, Stéphan A, Dutar P. A new neuronal target for beta-amyloid peptide in the rat hippocampus. Neurobiol Aging 2012; 33:1126.e1-14. [DOI: 10.1016/j.neurobiolaging.2011.11.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 11/10/2011] [Accepted: 11/20/2011] [Indexed: 02/03/2023]
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Stanley EM, Fadel JR, Mott DD. Interneuron loss reduces dendritic inhibition and GABA release in hippocampus of aged rats. Neurobiol Aging 2012; 33:431.e1-13. [PMID: 21277654 PMCID: PMC3110542 DOI: 10.1016/j.neurobiolaging.2010.12.014] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 12/02/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
Abstract
Aging is associated with impairments in learning and memory and a greater incidence of limbic seizures. These changes in the aged brain have been associated with increased excitability of hippocampal pyramidal cells caused by a reduced number of gamma-aminobutyric acid-ergic (GABAergic) interneurons. To better understand these issues, we performed cell counts of GABAergic interneurons and examined GABA efflux and GABAergic inhibition in area CA1 of the hippocampus of young (3-5 months) and aged (26-30 months) rats. Aging significantly reduced high K(+)/Ca(2+)-evoked GABA, but not glutamate efflux in area CA1. Immunostaining revealed a significant loss of GABAergic interneurons, but not inhibitory boutons in stratum oriens and stratum lacunosum moleculare. Somatostatin-immunoreactive oriens-lacunosum moleculare (O-LM) cells, but not parvalbumin-containing interneurons were selectively lost. Oriens-lacunosum moleculare cells project to distal dendrites of CA1 pyramidal cells, providing dendritic inhibition. Accordingly, inhibition of dendritic input to CA1 from entorhinal cortex was selectively reduced. These findings suggest that the age-dependent loss of interneurons impairs dendritic inhibition and dysregulates entorhinal cortical input to CA1, potentially contributing to cognitive impairment and seizures.
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Affiliation(s)
- Emily M. Stanley
- Department of Pharmacology, Physiology and Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208 USA
| | - Jim R. Fadel
- Department of Pharmacology, Physiology and Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208 USA
| | - David D. Mott
- Department of Pharmacology, Physiology and Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208 USA
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Kuruba R, Hattiangady B, Parihar VK, Shuai B, Shetty AK. Differential susceptibility of interneurons expressing neuropeptide Y or parvalbumin in the aged hippocampus to acute seizure activity. PLoS One 2011; 6:e24493. [PMID: 21915341 PMCID: PMC3167860 DOI: 10.1371/journal.pone.0024493] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 08/10/2011] [Indexed: 12/28/2022] Open
Abstract
Acute seizure (AS) activity in old age has an increased predisposition for evolving into temporal lobe epilepsy (TLE). Furthermore, spontaneous seizures and cognitive dysfunction after AS activity are often intense in the aged population than in young adults. This could be due to an increased vulnerability of inhibitory interneurons in the aged hippocampus to AS activity. We investigated this issue by comparing the survival of hippocampal GABA-ergic interneurons that contain the neuropeptide Y (NPY) or the calcium binding protein parvalbumin (PV) between young adult (5-months old) and aged (22-months old) F344 rats at 12 days after three-hours of AS activity. Graded intraperitoneal injections of the kainic acid (KA) induced AS activity and a diazepam injection at 3 hours after the onset terminated AS-activity. Measurement of interneuron numbers in different hippocampal subfields revealed that NPY+ interneurons were relatively resistant to AS activity in the aged hippocampus in comparison to the young adult hippocampus. Whereas, PV+ interneurons were highly susceptible to AS activity in both age groups. However, as aging alone substantially depleted these populations, the aged hippocampus after three-hours of AS activity exhibited 48% reductions in NPY+ interneurons and 70% reductions in PV+ interneurons, in comparison to the young hippocampus after similar AS activity. Thus, AS activity-induced TLE in old age is associated with far fewer hippocampal NPY+ and PV+ interneuron numbers than AS-induced TLE in the young adult age. This discrepancy likely underlies the severe spontaneous seizures and cognitive dysfunction observed in the aged people after AS activity.
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Affiliation(s)
- Ramkumar Kuruba
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, North Carolina, United States of America
- Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bharathi Hattiangady
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, North Carolina, United States of America
- Institute for Regenerative Medicine, Texas A&M Health Science Center at Scott & White, Temple, Texas, United States of America
- Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Vipan K. Parihar
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, North Carolina, United States of America
- Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bing Shuai
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, North Carolina, United States of America
- Institute for Regenerative Medicine, Texas A&M Health Science Center at Scott & White, Temple, Texas, United States of America
- Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Ashok K. Shetty
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, North Carolina, United States of America
- Institute for Regenerative Medicine, Texas A&M Health Science Center at Scott & White, Temple, Texas, United States of America
- Research Service, Central Texas Veterans Health Care System, Temple, Texas, United States of America
- Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Localization of pre- and postsynaptic cholinergic markers in rodent forebrain: a brief history and comparison of rat and mouse. Behav Brain Res 2010; 221:356-66. [PMID: 21129407 DOI: 10.1016/j.bbr.2010.11.051] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 11/23/2010] [Indexed: 11/23/2022]
Abstract
Rat and mouse models are widely used for studies in cognition and pathophysiology, among others. Here, we sought to determine to what extent these two model species differ for cholinergic and cholinoceptive features. For this purpose, we focused on cholinergic innervation patterns based on choline acetyltransferase (ChAT) immunostaining, and the expression of muscarinic acetylcholine receptors (mAChRs) detected immunocytochemically. In this brief review we first place cholinergic and cholinoceptive markers in a historic perspective, and then provide an overview of recent publications on cholinergic studies and techniques to provide a literature survey of current research. Next, we compare mouse (C57Bl/J6) and rat (Wistar) cholinergic and cholinoceptive systems simultaneously stained, respectively, for ChAT (analyzed qualitatively) and mAChRs (analyzed qualitatively and quantitatively). In general, the topographic cholinergic innervation patterns of both rodent species are highly comparable, with only considerable (but region specific) differences in number of detectable cholinergic interneurons, which are more numerous in rat. In contrast, immunolabeling for mAChRs, detected by the monoclonal antibody M35, differs markedly in the forebrain between the two species. In mouse brain, basal levels of activated and/or internalized mAChRs (as a consequence of cholinergic neurotransmission) are significantly higher. This suggests a higher cholinergic tone in mouse than rat, and hence the animal model of choice may have consequences for cholinergic drug testing experiments.
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Molecular changes in brain aging and Alzheimer's disease are mirrored in experimentally silenced cortical neuron networks. Neurobiol Aging 2010; 33:205.e1-18. [PMID: 20947216 DOI: 10.1016/j.neurobiolaging.2010.08.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/19/2010] [Accepted: 08/21/2010] [Indexed: 12/22/2022]
Abstract
Activity-dependent modulation of neuronal gene expression promotes neuronal survival and plasticity, and neuronal network activity is perturbed in aging and Alzheimer's disease (AD). Here we show that cerebral cortical neurons respond to chronic suppression of excitability by downregulating the expression of genes and their encoded proteins involved in inhibitory transmission (GABAergic and somatostatin) and Ca(2+) signaling; alterations in pathways involved in lipid metabolism and energy management are also features of silenced neuronal networks. A molecular fingerprint strikingly similar to that of diminished network activity occurs in the human brain during aging and in AD, and opposite changes occur in response to activation of N-methyl-D-aspartate (NMDA) and brain-derived neurotrophic factor (BDNF) receptors in cultured cortical neurons and in mice in response to an enriched environment or electroconvulsive shock. Our findings suggest that reduced inhibitory neurotransmission during aging and in AD may be the result of compensatory responses that, paradoxically, render the neurons vulnerable to Ca(2+)-mediated degeneration.
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Shetty AK, Hattiangady B, Rao MS. Vulnerability of hippocampal GABA-ergic interneurons to kainate-induced excitotoxic injury during old age. J Cell Mol Med 2010. [PMID: 20141618 DOI: 10.1111/j.1582-4934.2008.00675.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Hippocampal inhibitory interneurons expressing glutamate decarboxylase-67 (GAD-67) considerably decline in number during old age. Studies in young adult animals further suggest that hippocampal GAD-67+ interneuron population is highly vulnerable to excitotoxic injury. However, the relative susceptibility of residual GAD-67+ interneurons in the aged hippocampus to excitotoxic injury is unknown. To elucidate this, using both adult and aged F344 rats, we performed stereological counting of GAD-67+ interneurons in different layers of the dentate gyrus and CA1 & CA3 sub-fields, at 3 months post-excitotoxic hippocampal injury inflicted through an intracerebroventricular administration of kainic acid (KA). Substantial reductions of GAD-67+ interneurons were found in all hippocampal layers and sub-fields after KA-induced injury in adult animals. Contrastingly, there was no significant change in GAD-67+ interneuron population in any of the hippocampal layers and sub-fields following similar injury in aged animals. Furthermore, the stability of GAD-67+ interneurons in aged rats after KA was not attributable to milder injury, as the overall extent of KA-induced hippocampal principal neuron loss was comparable between adult and aged rats. Interestingly, because of the age-related disparity in vulnerability of interneurons to injury, the surviving GAD-67+ interneuron population in the injured aged hippocampus remained comparable to that observed in the injured adult hippocampus despite enduring significant reductions in interneuron number with aging. Thus, unlike in the adult hippocampus, an excitotoxic injury to the aged hippocampus does not result in significantly decreased numbers of GAD-67+ interneurons. Persistence of GAD-67+ interneuron population in the injured aged hippocampus likely reflects an age-related change in the response of GAD-67+ interneurons to excitotoxic hippocampal injury. These results have implications towards understanding mechanisms underlying the evolution of initial precipitating injury into temporal lobe epilepsy in the elderly population.
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Affiliation(s)
- Ashok K Shetty
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, NC, USA.
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Shetty AK, Hattiangady B, Rao MS. Vulnerability of hippocampal GABA-ergic interneurons to kainate-induced excitotoxic injury during old age. J Cell Mol Med 2010; 13:2408-23. [PMID: 20141618 DOI: 10.1111/j.1582-4934.2009.00675.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Hippocampal inhibitory interneurons expressing glutamate decarboxylase-67 (GAD-67) considerably decline in number during old age. Studies in young adult animals further suggest that hippocampal GAD-67+ interneuron population is highly vulnerable to excitotoxic injury. However, the relative susceptibility of residual GAD-67+ interneurons in the aged hippocampus to excitotoxic injury is unknown. To elucidate this, using both adult and aged F344 rats, we performed stereological counting of GAD-67+ interneurons in different layers of the dentate gyrus and CA1 & CA3 sub-fields, at 3 months post-excitotoxic hippocampal injury inflicted through an intracerebroventricular administration of kainic acid (KA). Substantial reductions of GAD-67+ interneurons were found in all hippocampal layers and sub-fields after KA-induced injury in adult animals. Contrastingly, there was no significant change in GAD-67+ interneuron population in any of the hippocampal layers and sub-fields following similar injury in aged animals. Furthermore, the stability of GAD-67+ interneurons in aged rats after KA was not attributable to milder injury, as the overall extent of KA-induced hippocampal principal neuron loss was comparable between adult and aged rats. Interestingly, because of the age-related disparity in vulnerability of interneurons to injury, the surviving GAD-67+ interneuron population in the injured aged hippocampus remained comparable to that observed in the injured adult hippocampus despite enduring significant reductions in interneuron number with aging. Thus, unlike in the adult hippocampus, an excitotoxic injury to the aged hippocampus does not result in significantly decreased numbers of GAD-67+ interneurons. Persistence of GAD-67+ interneuron population in the injured aged hippocampus likely reflects an age-related change in the response of GAD-67+ interneurons to excitotoxic hippocampal injury. These results have implications towards understanding mechanisms underlying the evolution of initial precipitating injury into temporal lobe epilepsy in the elderly population.
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Affiliation(s)
- Ashok K Shetty
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, NC, USA.
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Cazorla M, Jouvenceau A, Rose C, Guilloux JP, Pilon C, Dranovsky A, Prémont J. Cyclotraxin-B, the first highly potent and selective TrkB inhibitor, has anxiolytic properties in mice. PLoS One 2010; 5:e9777. [PMID: 20333308 PMCID: PMC2841647 DOI: 10.1371/journal.pone.0009777] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 02/19/2010] [Indexed: 11/19/2022] Open
Abstract
In the last decades, few mechanistically novel therapeutic agents have been developed to treat mental and neurodegenerative disorders. Numerous studies suggest that targeting BDNF and its TrkB receptor could be a promising therapeutic strategy for the treatment of brain disorders. However, the development of potent small ligands for the TrkB receptor has proven to be difficult. By using a peptidomimetic approach, we developed a highly potent and selective TrkB inhibitor, cyclotraxin-B, capable of altering TrkB-dependent molecular and physiological processes such as synaptic plasticity, neuronal differentiation and BDNF-induced neurotoxicity. Cyclotraxin-B allosterically alters the conformation of TrkB, which leads to the inhibition of both BDNF-dependent and -independent (basal) activities. Finally, systemic administration of cyclotraxin-B to mice results in TrkB inhibition in the brain with specific anxiolytic-like behavioral effects and no antidepressant-like activity. This study demonstrates that cyclotraxin-B might not only be a powerful tool to investigate the role of BDNF and TrkB in physiology and pathology, but also represents a lead compound for the development of new therapeutic strategies to treat brain disorders.
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Affiliation(s)
- Maxime Cazorla
- Neurobiology & Molecular Pharmacology, Centre de Psychiatrie et de Neurosciences, UMR-894 INSERM/Université Paris Descartes, Paris, France.
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A novel anti-inflammatory role of NCAM-derived mimetic peptide, FGL. Neurobiol Aging 2010; 31:118-28. [DOI: 10.1016/j.neurobiolaging.2008.03.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 03/03/2008] [Accepted: 03/20/2008] [Indexed: 11/22/2022]
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Xu C, Cui C, Alkon DL. Age-dependent enhancement of inhibitory synaptic transmission in CA1 pyramidal neurons via GluR5 kainate receptors. Hippocampus 2009; 19:706-17. [PMID: 19123252 DOI: 10.1002/hipo.20544] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Changes in hippocampal synaptic networks during aging may contribute to age-dependent compromise of cognitive functions such as learning and memory. Previous studies have demonstrated that GABAergic synaptic transmission exhibits age-dependent changes. To better understand such age-dependent changes of GABAergic synaptic inhibition, we performed whole-cell recordings from pyramidal cells in the CA1 area of acute hippocampal slices on aged (24-26 months old) and young (2-4 months old) Brown-Norway rats. We found that the frequency and amplitude of spontaneous inhibitory postsynaptic current (IPSCs) were significantly increased in aged rats, but the frequency and amplitude of mIPSCs were decreased. Furthermore, the regulation of GABAergic synaptic transmission by GluR5 containing kainate receptors was enhanced in aged rats, which was revealed by using LY382884 (a GluR5 kainate receptor antagonist) and ATPA (a GluR5 kainate receptor agonist). Moreover, we demonstrated that vesicular glutamate transporters are involved in the kainate receptor dependent regulation of sIPSCs. Taken together, these results suggest that GABAergic synaptic transmission is potentiated in aged rats, and GluR5 containing kainate receptors regulate the inhibitory synaptic transmission through endogenous glutamate. These alterations of GABAergic input with aging could contribute to age-dependent cognitive decline.
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Affiliation(s)
- Changqing Xu
- Blanchette Rockefeller Neurosciences Institute, Rockville, Maryland 20850-3332, USA.
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Somatostatin, Alzheimer's disease and cognition: An old story coming of age? Prog Neurobiol 2009; 89:153-61. [DOI: 10.1016/j.pneurobio.2009.07.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 04/27/2009] [Accepted: 07/02/2009] [Indexed: 12/21/2022]
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Murchison D, McDermott AN, Lasarge CL, Peebles KA, Bizon JL, Griffith WH. Enhanced calcium buffering in F344 rat cholinergic basal forebrain neurons is associated with age-related cognitive impairment. J Neurophysiol 2009; 102:2194-207. [PMID: 19675291 DOI: 10.1152/jn.00301.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Alterations in neuronal Ca(2+) homeostasis are important determinants of age-related cognitive impairment. We examined the Ca(2+) influx, buffering, and electrophysiology of basal forebrain neurons in adult, middle-aged, and aged male F344 behaviorally assessed rats. Middle-aged and aged rats were characterized as cognitively impaired or unimpaired by water maze performance relative to young cohorts. Patch-clamp experiments were conducted on neurons acutely dissociated from medial septum/nucleus of the diagonal band with post hoc identification of phenotypic marker mRNA using single-cell RT-PCR. We measured whole cell calcium and barium currents and dissected these currents using pharmacological agents. We combined Ca(2+) current recording with Ca(2+)-sensitive ratiometric microfluorimetry to measure Ca(2+) buffering. Additionally, we sought changes in neuronal firing properties using current-clamp recording. There were no age- or cognition-related changes in the amplitudes or fractional compositions of the whole cell Ca(2+) channel currents. However, Ca(2+) buffering was significantly enhanced in cholinergic neurons from aged cognitively impaired rats. Moreover, increased Ca(2+) buffering was present in middle-aged rats that were not cognitively impaired. Firing properties were largely unchanged with age or cognitive status, except for an increase in the slow afterhyperpolarization in aged cholinergic neurons, independent of cognitive status. Furthermore, acutely dissociated basal forebrain neurons in which choline acetyltransferase mRNA was detected had the electrophysiological profiles of identified cholinergic neurons. We conclude that enhanced Ca(2+) buffering by cholinergic basal forebrain neurons may be important during aging.
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Affiliation(s)
- David Murchison
- 1Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College Station, Texas77843-1114, USA
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Bond AM, Vangompel MJW, Sametsky EA, Clark MF, Savage JC, Disterhoft JF, Kohtz JD. Balanced gene regulation by an embryonic brain ncRNA is critical for adult hippocampal GABA circuitry. Nat Neurosci 2009; 12:1020-7. [PMID: 19620975 PMCID: PMC3203213 DOI: 10.1038/nn.2371] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 06/19/2009] [Indexed: 12/19/2022]
Abstract
Genomic studies demonstrate that while the majority of the mammalian genome is transcribed, only about 2% of these transcripts are protein coding. We have been investigating how the long, polyadenylated Evf2 non-coding RNA regulates transcription of homeodomain transcription factors DLX5 and DLX6 in the developing mouse forebrain. Here we show that in developing ventral forebrain, Evf2 recruits DLX and MECP2 transcription factors to key DNA regulatory elements in the Dlx 5/6 intergenic region and controls Dlx5, Dlx6, and GAD67 expression through trans and cis-acting mechanisms. Evf2 mouse mutants have reduced numbers of GABAergic interneurons in early post-natal hippocampus and dentate gyrus. Although the numbers of GABAergic interneurons and GAD67 RNA levels return to normal in Evf2 mutant adult hippocampus, reduced synaptic inhibition occurs. These results suggest that non-coding RNA-dependent balanced gene regulation in embryonic brain is critical for proper formation of GABA-dependent neuronal circuitry in adult brain.
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Affiliation(s)
- Allison M Bond
- Developmental Biology and Department of Pediatrics, Children's Memorial Hospital and Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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Banerjee PS, Aston J, Khundakar AA, Zetterström TSC. Differential regulation of psychostimulant-induced gene expression of brain derived neurotrophic factor and the immediate-early gene Arc in the juvenile and adult brain. Eur J Neurosci 2009; 29:465-76. [PMID: 19222557 DOI: 10.1111/j.1460-9568.2008.06601.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Psychostimulant drugs are widely used in children for the treatment of attention-deficit/hyperactivity disorder. Recent animal studies have suggested that exposure to these agents in early life could be detrimental to brain development. Here, for the first time, the effect of methylphenidate (MPH) and D-amphetamine (AMPH) on the expression of two key genes for neuronal development and plasticity, brain-derived neurotrophic factor (bdnf) and the effector immediate early gene activity-regulated, cytoskeletal-associated protein (Arc), was examined in both juvenile and adult rats. Both MPH [2 mg/kg, intraperitoneal (i.p.)] and AMPH (0.5 mg/kg, i.p.) induced marked decreases of bdnf mRNA in hippocampal and cortical brain regions of juveniles, whereas effects in adults were significantly less (hippocampus) or opposite (frontal cortex). In comparison, Arc mRNA was decreased (hippocampus and parietal cortex), largely unaffected (frontal cortex) or increased (striatum) in juveniles, whereas in adults, Arc mRNA increased in most brain regions. MPH-induced locomotion was also measured, and showed a much smaller increase in juveniles than in adults. In summary, our data show that the effects of MPH and AMPH on expression of the neurodevelopmentally important genes, bdnf and Arc, differ markedly in juvenile and adult rats, with juveniles showing evidence of brain region-specific decreases in both genes. These age-dependent effects on gene expression may be linked with the reported long-term harmful effects of psychostimulants in animal models.
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Affiliation(s)
- Partha S Banerjee
- Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, The Gateway, Leicester, UK
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Age-related changes in GAD levels in the central auditory system of the rat. Exp Gerontol 2009; 44:161-9. [DOI: 10.1016/j.exger.2008.09.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 09/22/2008] [Accepted: 09/29/2008] [Indexed: 11/22/2022]
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Lee CH, Hwang IK, Yoo KY, Choi JH, Park OK, Lee IS, Won MH. Parvalbumin immunoreactivity and protein level are altered in the gerbil hippocampus during normal aging. Neurochem Res 2008; 33:2222-8. [PMID: 18427987 DOI: 10.1007/s11064-008-9699-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 04/03/2008] [Indexed: 01/18/2023]
Abstract
Hippocampal interneurons are local circuit neurons which are responsible for inhibitory activity in the hippocampus. Parvalbumin (PV) is one of useful markers for GABAergic interneurons, not for principle cells, in the hippocampus. In the present study, we investigated age-related changes in PV immunoreactive neurons and protein levels in the gerbil hippocampus during normal aging. PV immunoreactive neurons were detected in all hippocampal subregions of all groups. PV immunoreactive neurons, which innervated principal neurons, were non-pyramidal neurons in the hippocampal CA1-3 regions, and were polymorphic neurons in the dentate gyrus. In the hippocampal CA1 region, the number of PV immunoreactive neurons was significantly reduced in the postnatal month 3 (PM 3) group, which was sustained by PM 18, and, at PM 24, the number of PV immunoreactive neurons was significantly decreased. In the CA2/3 region and dentate gyrus, the number of PV immunoreactive neurons was significantly decreased at PM 6: Thereafter, the number of PV immunoreactive neurons was sustained until PM 24. In addition, changes in PV protein levels in the gerbil hippocampus were similar to immunohistochemical changes during normal aging: PV protein levels were significantly decreased with age by PM 6: Thereafter, PV protein levels were sustained by PM 24. These results suggest that PV immunoreactive interneurons were decreased in the hippocampus with age in gerbils.
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Affiliation(s)
- Choong Hyun Lee
- Department of Anatomy and Cell Biology, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Seoul, 151-742, South Korea
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Gant JC, Thibault O. Action potential throughput in aged rat hippocampal neurons: regulation by selective forms of hyperpolarization. Neurobiol Aging 2008; 30:2053-64. [PMID: 18367293 DOI: 10.1016/j.neurobiolaging.2008.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 02/07/2008] [Accepted: 02/14/2008] [Indexed: 01/23/2023]
Abstract
At hippocampal synapses, repetitive synaptic stimulation (RSS) in the theta frequency range (3-12Hz) is associated with robust EPSP frequency facilitation (FF) and consequently, enhanced action potential (spike) generation and throughput. A complex, synaptically induced hyperpolarization (SIHP) is also triggered by synaptic activation, and a Ca(2+)-dependent afterhyperpolarization (AHP) is triggered above spike threshold. With aging, the AHP is increased and impairs intracellular spike generation, at least in accommodation protocols. However, little is known about how these aging changes interact to affect spike generation at physiological frequencies of RSS, or if the SIHP also is modified in aging. Here we performed the first tests of the net impact of these excitatory and inhibitory aging changes on spike generation during RSS. We report that during RSS at spike threshold (1) spike throughput is well sustained at theta frequencies in young and aged neurons; (2) an interposed AHP dampens spike generation, particularly in aged neurons and at higher frequencies; (3) compared to the AHP, the SIHP does not exert an equivalent inhibitory effect on spike throughput; and (4) in contrast to the AHP, the SIHP is reduced with aging. Together, these results are consistent with a model in which the source of the hyperpolarization is important in determining hippocampal spike throughput within the theta frequency range.
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Affiliation(s)
- John C Gant
- Department of Molecular and Biomedical Pharmacology, University of Kentucky Medical Center (UKMC), MS320, Lexington, KY 40503, United States.
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Activation of the medial septum reverses age-related hippocampal encoding deficits: a place field analysis. J Neurosci 2008; 28:1841-53. [PMID: 18287501 DOI: 10.1523/jneurosci.4629-07.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
When a rat runs through a familiar environment, the hippocampus retrieves a previously stored spatial representation of the environment. When the environment is modified a new representation is seen, presumably corresponding to the hippocampus encoding the new information. The medial septum is hypothesized to modulate whether the hippocampus engages in retrieval or encoding. The cholinergic agonist carbachol was infused into the medial septum, and hippocampal CA1 place cells were recorded in freely moving rats. In a familiar environment, septal activation impaired the retrieval of a previously stored hippocampal place cell representation regardless of age. When the environment was changed, medial septal activation impaired the encoding process in young, but facilitated the encoding of the new information in aged rats. Moreover, the improved encoding was evident during a subsequent exposure to the modified environment 24 h later. The findings support the role the septum plays in modulating hippocampal retrieval/encoding states. Furthermore, our data indicate a mechanism of age-related cognitive impairment.
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Alkondon M, Pereira EFR, Albuquerque EX. Age-dependent changes in the functional expression of two nicotinic receptor subtypes in CA1 stratum radiatum interneurons in the rat hippocampus. Biochem Pharmacol 2007; 74:1134-44. [PMID: 17645875 DOI: 10.1016/j.bcp.2007.06.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 06/12/2007] [Accepted: 06/15/2007] [Indexed: 11/17/2022]
Abstract
Protein density measurements and mRNA analysis have provided valuable information on age-dependent changes in the distribution of different nicotinic receptor (nAChR) subtypes in various areas of the rat brain, including the hippocampus. However, very little is known regarding the functional expression of nAChRs in individual neuron types at various ages. Likewise, there is paucity of information regarding the functional and pharmacological profile of nAChRs in the mature rat hippocampus. To address these issues, we used the whole-cell patch-clamp technique to record nicotinic responses from CA1 stratum radiatum (SR) interneurons in hippocampal slices from rat pups (5-19 days old) and adult rats (2-5 months old). As previously observed in the hippocampus of rat pups, CA1 SR interneurons in the hippocampus of adult rats responded to choline (10mM, 12s) with whole-cell currents that decayed to the baseline within the agonist pulse, were sensitive to inhibition by methyllycaconitine (10nM) or alpha-bungarotoxin (50 nM), and were, therefore, mediated by alpha7*(1)[1] nAChRs. Likewise, as previously observed in the hippocampus of young rats, in the adult rat hippocampus excitatory postsynaptic currents (EPSCs) were recorded from SR interneurons in response to a pulse of ACh (0.1 mM, 12s) applied in the presence of the GABA(A) receptor antagonist bicuculline. ACh-triggered EPSCs were inhibited by mecamylamine (1 microM) or choline (1 mM) and were, therefore, likely to have resulted from activation of alpha3beta4beta2* nAChR. The magnitude of alpha7* nAChR-mediated responses increased with the age of the animals. In contrast, the magnitude of alpha3beta4beta2* nAChR-mediated responses was highest at the second postnatal week. The distinct age dependency of functional expression of alpha7* and alpha3beta4beta2* nAChRs strongly suggests that the excitability of CA1 SR interneurons is differentially regulated by the nicotinic cholinergic system in the hippocampus of rat pups and adult rats.
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Affiliation(s)
- Manickavasagom Alkondon
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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