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Li C, Li Z, Xu S, Jiang S, Ye Z, Yu B, Gong S, Li J, Hu Q, Feng B, Wang M, Lu C. Exogenous AMPA downregulates gamma-frequency network oscillation in CA3 of rat hippocampal slices. Sci Rep 2023; 13:10548. [PMID: 37386056 PMCID: PMC10310770 DOI: 10.1038/s41598-023-36876-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 06/12/2023] [Indexed: 07/01/2023] Open
Abstract
Pharmacologically-induced persistent hippocampal γ oscillation in area CA3 requires activation of α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs). However, we demonstrated that exogenous AMPA dose-dependently inhibited carbachol (CCH)-induced γ oscillation in the CA3 area of rat hippocampal slices, but the underlying mechanism is not clear. Application of AMPARs antagonist NBQX (1 μM) did not affect γ oscillation power (γ power), nor AMPA-mediated γ power reduction. At 3 μM, NBQX had no effect on γ power but largely blocked AMPA-mediated γ power reduction. Ca2+-permeable AMPA receptor (CP-AMPAR) antagonist IEM1460 or CaMKK inhibitor STO-609 but not CaMKIIα inhibitor KN93 enhanced γ power, indicating that activation of CP-AMPAR or CaMKK negatively modulated CCH-induced γ oscillation. Either CP-AMPAR antagonist or CaMKK inhibitor alone did not affected AMPA-mediated γ power reduction, but co-administration of IEM1460 and NBQX (1 μM) largely prevented AMPA-mediated downregulation of γ suggesting that CP-AMPARs and CI-AMPARs are involved in AMPA downregulation of γ oscillation. The recurrent excitation recorded at CA3 stratum pyramidale was significantly reduced by AMPA application. Our results indicate that AMPA downregulation of γ oscillation may be related to the reduced recurrent excitation within CA3 local neuronal network due to rapid CI-AMPAR and CP-AMPAR activation.
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Affiliation(s)
- Chengzhang Li
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Zhenrong Li
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Sihan Xu
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Sanwei Jiang
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Zhenli Ye
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Bin Yu
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Shixiang Gong
- School of Information Science and Engineering, Yanshan University, Qinhuangdao, China
| | - Junmei Li
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Qilin Hu
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Bingyan Feng
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Mengmeng Wang
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Chengbiao Lu
- Henan International Key Laboratory for Noninvasive Neuromodulation/Key Laboratory of Brain Research of Henan Province, Department of Physiology & Pathophysiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China.
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2
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Biophysical and synaptic properties of regular spiking interneurons in hippocampal area CA3 of aged rats. Neurobiol Aging 2021; 112:27-38. [PMID: 35041997 DOI: 10.1016/j.neurobiolaging.2021.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 12/11/2022]
Abstract
Neuronal processing from the dentate gyrus to the hippocampus is critical for storage and recovery of new memory traces. In area CA3, GABAergic interneurons form a strong barrage of inhibition that modulates pyramidal cells. A well-established feature of aging is decreased GABAergic inhibition, a phenomenon that contributes to the exacerbated excitability of aged pyramidal cells. In hippocampal slices of aged rats (22-28 months old) we examined the properties of regular spiking CA3 interneurons with patch-clamp whole-cell recordings. We found enhanced firing discharge without altering the maximal firing rate of aged regular spiking interneurons. In the mossy fibers (MF) to interneurons synapse, a switch in the AMPA receptor subunit composition was found in aged interneurons. Young regular spiking interneurons predominantly express CP AMPA receptors and MF LTD. By contrast, aged regular spiking interneurons contain a higher proportion of CI AMPA receptors and respond with MF LTP. We show for the first time that the specialized MF terminals contacting interneurons, retain synaptic capabilities and provide a novel insight of the interneuron's function during aging.
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The Control of Rat Hippocampal Gamma Oscillation Strength by BK Channel Activity. Neuroscience 2021; 475:220-228. [PMID: 34509547 DOI: 10.1016/j.neuroscience.2021.09.002] [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: 03/04/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 11/20/2022]
Abstract
Neuronal network oscillations in the gamma frequency band (30-80 Hz, γ oscillations) are associated with the higher brain functions such as perception, attention, learning and memory. BK channels mediate rapid repolarization and fast afterhyperpolarization in neurons and control neuronal excitability, and potentially control hippocampal γ oscillations. In this study, we examined the effects of modulating BK channels on hippocampal γ oscillations in the absence or presence of Ca2+ influx through voltage-gated Ca2+ channels (VGCC) or Ca2+-permeable AMPA receptors (CP-AMPAR). We found that blocking BK channels enhanced γ power, without affecting oscillation frequency or regularity, suggesting that BK channel activity suppresses γ oscillations. Blocking either VGCC or CP-AMPAR itself enhanced γ power, and completely occluded the effect of BK channel blockers on γ oscillations, whereas blocking BK channels first could not prevent a further γ power increase upon blockade of either CP-AMPAR or VGCC. We propose that Ca2+ influx through VGCC or CP-AMPAR during γ oscillations, cause membrane BK channel activation and regulate hippocampal γ oscillation strength by negative feedback.
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4
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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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Dabaghian Y. From Topological Analyses to Functional Modeling: The Case of Hippocampus. Front Comput Neurosci 2021; 14:593166. [PMID: 33505262 PMCID: PMC7829363 DOI: 10.3389/fncom.2020.593166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 12/02/2020] [Indexed: 11/13/2022] Open
Abstract
Topological data analyses are widely used for describing and conceptualizing large volumes of neurobiological data, e.g., for quantifying spiking outputs of large neuronal ensembles and thus understanding the functions of the corresponding networks. Below we discuss an approach in which convergent topological analyses produce insights into how information may be processed in mammalian hippocampus—a brain part that plays a key role in learning and memory. The resulting functional model provides a unifying framework for integrating spiking data at different timescales and following the course of spatial learning at different levels of spatiotemporal granularity. This approach allows accounting for contributions from various physiological phenomena into spatial cognition—the neuronal spiking statistics, the effects of spiking synchronization by different brain waves, the roles played by synaptic efficacies and so forth. In particular, it is possible to demonstrate that networks with plastic and transient synaptic architectures can encode stable cognitive maps, revealing the characteristic timescales of memory processing.
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Affiliation(s)
- Yuri Dabaghian
- Department of Neurology, The University of Texas McGovern Medical School, Houston, TX, United States
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6
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Kumar A. Calcium Signaling During Brain Aging and Its Influence on the Hippocampal Synaptic Plasticity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:985-1012. [PMID: 31646542 DOI: 10.1007/978-3-030-12457-1_39] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Calcium (Ca2+) ions are highly versatile intracellular signaling molecules and are universal second messenger for regulating a variety of cellular and physiological functions including synaptic plasticity. Ca2+ homeostasis in the central nervous system endures subtle dysregulation with advancing age. Research has provided abundant evidence that brain aging is associated with altered neuronal Ca2+ regulation and synaptic plasticity mechanisms. Much of the work has focused on the hippocampus, a brain region critically involved in learning and memory, which is particularly susceptible to dysfunction during aging. The current chapter takes a specific perspective, assessing various Ca2+ sources and the influence of aging on Ca2+ sources and synaptic plasticity in the hippocampus. Integrating the knowledge of the complexity of age-related alterations in neuronal Ca2+ signaling and synaptic plasticity mechanisms will positively shape the development of highly effective therapeutics to treat brain disorders including cognitive impairment associated with aging and neurodegenerative disease.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
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7
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Zallo F, Gardenal E, Verkhratsky A, Rodríguez JJ. Loss of calretinin and parvalbumin positive interneurones in the hippocampal CA1 of aged Alzheimer's disease mice. Neurosci Lett 2018; 681:19-25. [PMID: 29782955 DOI: 10.1016/j.neulet.2018.05.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/30/2018] [Accepted: 05/17/2018] [Indexed: 01/19/2023]
Abstract
Neuronal degeneration associated with Alzheimer's disease (AD), is linked to impaired calcium homeostasis and to changes in calcium-binding proteins (CBPs). The AD-related modification of neuronal CBPs remains controversial. Here we analysed the presence and expression of calretinin (CR) and parvalbumin (PV) in the hippocampal CA1 neurones of 18 months old 3xTg-AD mice compared to non-Tg animals. We found a layer specific decrease in number of interneurones expressing CR and PV (by 33.7% and 52%, respectively). Expression of PV decreased (by 13.8%) in PV-positive neurones, whereas expression of CR did not change in CR positive cells. The loss of specific subpopulations of Ca2+-binding proteins expressing interneurones (CR and PV) together with the decrease of PV in the surviving cells may be linked to their vulnerability to AD pathology. Specific loss of inhibitory interneurones with age could contribute to overall increase in the network excitability associated with AD.
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Affiliation(s)
- Fatima Zallo
- BioCruces Health Research Institute, 48903, Barakaldo, Spain; Department of Neuroscience, University of the Basque Country UPV/EHU, 48940, Leioa, Spain
| | - Emanuela Gardenal
- Department of Neuroscience, University of the Basque Country UPV/EHU, 48940, Leioa, Spain; Human Histology and Embryology Unit, Medical School, University of Verona, 37134, Verona, Italy
| | - Alexei Verkhratsky
- Department of Neuroscience, University of the Basque Country UPV/EHU, 48940, Leioa, Spain; IKERBASQUE, Basque Foundation for Science, 48013-Bilbao, Medical School, Spain; Achúcarro Basque Center for Neuroscience, 48940, Leioa, Spain; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PL, United Kingdom; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
| | - José Julio Rodríguez
- BioCruces Health Research Institute, 48903, Barakaldo, Spain; Department of Neuroscience, University of the Basque Country UPV/EHU, 48940, Leioa, Spain; IKERBASQUE, Basque Foundation for Science, 48013-Bilbao, Medical School, Spain.
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8
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Lopez JR, Uryash A, Kolster J, Estève E, Zhang R, Adams JA. Enhancing Endogenous Nitric Oxide by Whole Body Periodic Acceleration Elicits Neuroprotective Effects in Dystrophic Neurons. Mol Neurobiol 2018; 55:8680-8694. [DOI: 10.1007/s12035-018-1018-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 03/16/2018] [Indexed: 12/25/2022]
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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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10
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Wang J, He X, Guo F, Cheng X, Wang Y, Wang X, Feng Z, Vreugdenhil M, Lu C. Multiple Kinases Involved in the Nicotinic Modulation of Gamma Oscillations in the Rat Hippocampal CA3 Area. Front Cell Neurosci 2017; 11:57. [PMID: 28321180 PMCID: PMC5337687 DOI: 10.3389/fncel.2017.00057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/15/2017] [Indexed: 11/29/2022] Open
Abstract
Neuronal synchronization at gamma band frequency (20–80 Hz, γ oscillations) is closely associated with higher brain function, such as learning, memory and attention. Nicotinic acetylcholine receptors (nAChRs) are highly expressed in the hippocampus, and modulate hippocampal γ oscillations, but the intracellular mechanism underlying such modulation remains elusive. We explored multiple kinases by which nicotine can modulate γ oscillations induced by kainate in rat hippocampal area CA3 in vitro. We found that inhibitors of cyclic AMP dependent kinase (protein kinase A, PKA), protein kinase C (PKC), N-methyl-D-aspartate receptor (NMDA) receptors, Phosphoinositide 3-kinase (PI3K) and extracellular signal-related kinases (ERK), each individually could prevent the γ oscillation-enhancing effect of 1 μM nicotine, whereas none of them affected baseline γ oscillation strength. Inhibition of the serine/threonine kinase Akt increased baseline γ oscillations and partially blocked its nicotinic enhancement. We propose that the PKA-NMDAR-PI3K-ERK pathway modifies cellular properties required for the nicotinic enhancement of γ oscillations, dependent on a PKC-ERK mediated pathway. These signaling pathways provide clues for restoring γ oscillations in pathological conditions affecting cognition. The suppression of γ oscillations at 100 μM nicotine was only dependent on PKA-NMDAR activation and may be due to very high intracellular calcium levels.
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Affiliation(s)
- JianGang Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical UniversityXinxinang, China; Department of Pathophysiology, Xinxiang Medical UniversityXinxinang, China
| | - XiaoLong He
- Key Laboratory of Neuronal Oscillation and Disease, Yantze University Medical School JingZhou, China
| | - Fangli Guo
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical UniversityXinxinang, China; Department of Neurobiology and Physiology, Xinxiang Medical UniversityXinxinang, China
| | - XiangLin Cheng
- Department of Laboratory Medicine, Yantze University Affiliated Hospital JingZhou, China
| | - Yali Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical UniversityXinxinang, China; Department of Neurobiology and Physiology, Xinxiang Medical UniversityXinxinang, China
| | - XiaoFang Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University Xinxinang, China
| | - ZhiWei Feng
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University Xinxinang, China
| | - Martin Vreugdenhil
- Department of Psychology, Xinxiang Medical UniversityXinxinang, China; School of Life Sciences, Birmingham City UniversityBirmingham, UK
| | - ChengBiao Lu
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical UniversityXinxinang, China; Key Laboratory of Neuronal Oscillation and Disease, Yantze University Medical SchoolJingZhou, China; Department of Neurobiology and Physiology, Xinxiang Medical UniversityXinxinang, China
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11
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Lopez JR, Kolster J, Uryash A, Estève E, Altamirano F, Adams JA. Dysregulation of Intracellular Ca 2+ in Dystrophic Cortical and Hippocampal Neurons. Mol Neurobiol 2016; 55:603-618. [PMID: 27975174 DOI: 10.1007/s12035-016-0311-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 11/21/2016] [Indexed: 12/13/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an inherited X-linked disorder characterized by skeletal muscle wasting, cardiomyopathy, as well as cognitive impairment. Lack of dystrophin in striated muscle produces dyshomeostasis of resting intracellular Ca2+ ([Ca2+]i), Na+ ([Na+]i), and oxidative stress. Here, we test the hypothesis that similar to striated muscle cells, an absence of dystrophin in neurons from mdx mice (a mouse model for DMD) is also associated with dysfunction of [Ca2+]i homeostasis and oxidative stress. [Ca2+]i and [Na+]i in pyramidal cortical and hippocampal neurons from 3 and 6 months mdx mice were elevated compared to WT in an age-dependent manner. Removal of extracellular Ca2+ reduced [Ca2+]i in both WT and mdx neurons, but the decrease was greater and age-dependent in the latter. GsMTx-4 (a blocker of stretch-activated cation channels) significantly decreased [Ca2+]i and [Na+]i in an age-dependent manner in all mdx neurons. Blockade of ryanodine receptors (RyR) or inositol triphosphate receptors (IP3R) reduced [Ca2+]i in mdx. Mdx neurons showed elevated and age-dependent reactive oxygen species (ROS) production and an increase in neuronal damage. In addition, mdx mice showed a spatial learning deficit compared to WT. GsMTx-4 intraperitoneal injection reduced neural [Ca2+]i and improved learning deficit in mdx mice. In summary, mdx neurons show an age-dependent dysregulation in [Ca2+]i and [Na+]i which is mediated by plasmalemmal cation influx and by intracellular Ca2+ release through the RyR and IP3R. Also, mdx neurons have elevated ROS production and more extensive cell damage. Finally, a reduction of [Ca2+]i improved cognitive function in mdx mice.
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Affiliation(s)
- José R Lopez
- Department of Molecular Biosciences, University of California, Davis, CA, 95616, USA.
| | - Juan Kolster
- Centro de Investigaciones Biomédicas, Mexico, México
| | - Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, 33140, USA
| | - Eric Estève
- HP2 INSERM 1042 Institut Jean Roget, Université Grenoble Alpes, BP170, 38042, Grenoble Cedex, France
| | - Francisco Altamirano
- Department of Molecular Biosciences, University of California, Davis, CA, 95616, USA.,Department of Internal Medicine - Cardiology, University of Texas Southwestern Medical Center, Dallas, TX, 75235, USA
| | - José A Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, 33140, USA
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12
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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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13
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Basso E, Arai M, Dabaghian Y. Gamma Synchronization Influences Map Formation Time in a Topological Model of Spatial Learning. PLoS Comput Biol 2016; 12:e1005114. [PMID: 27636199 PMCID: PMC5026372 DOI: 10.1371/journal.pcbi.1005114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/20/2016] [Indexed: 12/30/2022] Open
Abstract
The mammalian hippocampus plays a crucial role in producing a cognitive map of space-an internalized representation of the animal's environment. We have previously shown that it is possible to model this map formation using a topological framework, in which information about the environment is transmitted through the temporal organization of neuronal spiking activity, particularly those occasions in which the firing of different place cells overlaps. In this paper, we discuss how gamma rhythm, one of the main components of the extracellular electrical field potential affects the efficiency of place cell map formation. Using methods of algebraic topology and the maximal entropy principle, we demonstrate that gamma modulation synchronizes the spiking of dynamical cell assemblies, which enables learning a spatial map at faster timescales.
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Affiliation(s)
- Edward Basso
- Department of Physics, Rice University, Houston, Texas, United States of America
| | - Mamiko Arai
- Department of Mathematics, Tokyo Women’s Christian University, 2-6-1 Zempukuji, Suginami-ku, Tokyo, Japan
| | - Yuri Dabaghian
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Computational and Applied Mathematics, Rice University, Houston, Texas, United States of America
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14
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Jessen SB, Mathiesen C, Lind BL, Lauritzen M. Interneuron Deficit Associates Attenuated Network Synchronization to Mismatch of Energy Supply and Demand in Aging Mouse Brains. Cereb Cortex 2015; 27:646-659. [DOI: 10.1093/cercor/bhv261] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Sanne Barsballe Jessen
- Department of Neuroscience and Pharmacology
- Center for Healthy Aging, University of Copenhagen, Copenhagen N 2200, Denmark
| | - Claus Mathiesen
- Department of Neuroscience and Pharmacology
- Center for Healthy Aging, University of Copenhagen, Copenhagen N 2200, Denmark
| | | | - Martin Lauritzen
- Department of Neuroscience and Pharmacology
- Center for Healthy Aging, University of Copenhagen, Copenhagen N 2200, Denmark
- Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup 2600, Denmark
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15
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Wang Y, Wang Z, Wang J, Wang Y, Henderson Z, Wang X, Zhang X, Song J, Lu C. The modulation of nicotinic acetylcholine receptors on the neuronal network oscillations in rat hippocampal CA3 area. Sci Rep 2015; 5:9493. [PMID: 25810076 PMCID: PMC4374140 DOI: 10.1038/srep09493] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/05/2015] [Indexed: 11/28/2022] Open
Abstract
γ oscillations are associated with higher brain functions such as memory, perception and consciousness. Disruption of γ oscillations occur in various neuro-psychological disorders such as schizophrenia. Nicotinic acetylcholine receptors (nAChR) are highly expressed in the hippocampus, however, little is known about the role on hippocampal persistent γ oscillation. This study examined the effects of nicotine and selective nAChR agonists and antagonists on kainate-induced persistent γ oscillation in rat hippocampal slices. Nicotine enhanced γ oscillation at concentrations of 0.1–10 μM, but reduced it at a higher concentration of 100 μM. The enhancement on γ oscillation can be best mimicked by co-application of α4β2- and α7- nAChR agonist and reduced by a combination of nAChR antagonists, DhβE and MLA. However, these nAChR antagonists failed to block the suppressing role of nicotine on γ. Furthermore, we found that the NMDA receptor antagonist D-AP5 completely blocked the effect of nicotine. These results demonstrate that nicotine modulates γ oscillations via α7 and α4β2 nAChR as well as NMDA activation, suggesting that nAChR activation may have a therapeutic role for the clinical disorder such as schizophrenia, which is known to have impaired γ oscillation and hypo-NMDA receptor function.
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Affiliation(s)
- Yang Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Zhan Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Jiangang Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Yali Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Zaineb Henderson
- Institute of Membrane and System Biology, University of Leeds, Leeds, England
| | - Xiaofang Wang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Xi Zhang
- Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China
| | - Jinggui Song
- Psychiatric Hospital of Henan Province, 2nd Affiliated Hospital of Xinxiang Medical University
| | - Chengbiao Lu
- 1] Key Laboratory for the Brain Research of Henan Province, Xinxiang Medical University, Henan Province, Henan PR. China [2] Psychiatric Hospital of Henan Province, 2nd Affiliated Hospital of Xinxiang Medical University
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16
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Rizzo V, Richman J, Puthanveettil SV. Dissecting mechanisms of brain aging by studying the intrinsic excitability of neurons. Front Aging Neurosci 2015; 6:337. [PMID: 25610394 PMCID: PMC4285138 DOI: 10.3389/fnagi.2014.00337] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 11/29/2014] [Indexed: 01/30/2023] Open
Abstract
Several studies using vertebrate and invertebrate animal models have shown aging associated changes in brain function. Importantly, changes in soma size, loss or regression of dendrites and dendritic spines and alterations in the expression of neurotransmitter receptors in specific neurons were described. Despite this understanding, how aging impacts intrinsic properties of individual neurons or circuits that govern a defined behavior is yet to be determined. Here we discuss current understanding of specific electrophysiological changes in individual neurons and circuits during aging.
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Affiliation(s)
- Valerio Rizzo
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
| | - Jeffrey Richman
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
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17
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Singhal K, Sandhir R. L-type calcium channel blocker ameliorates diabetic encephalopathy by modulating dysregulated calcium homeostasis. J Neurosci Res 2014; 93:296-308. [DOI: 10.1002/jnr.23478] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/20/2014] [Accepted: 08/07/2014] [Indexed: 01/02/2023]
Affiliation(s)
- Kirti Singhal
- Department of Biochemistry; Panjab University; Chandigarh India
| | - Rajat Sandhir
- Department of Biochemistry; Panjab University; Chandigarh India
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18
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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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19
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Gant JC, Blalock EM, Chen KC, Kadish I, Porter NM, Norris CM, Thibault O, Landfield PW. FK506-binding protein 1b/12.6: a key to aging-related hippocampal Ca2+ dysregulation? Eur J Pharmacol 2013; 739:74-82. [PMID: 24291098 DOI: 10.1016/j.ejphar.2013.10.070] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/16/2013] [Accepted: 10/17/2013] [Indexed: 12/25/2022]
Abstract
It has been recognized for some time that the Ca(2+)-dependent slow afterhyperpolarization (sAHP) is larger in hippocampal neurons of aged compared with young animals. In addition, extensive studies since have shown that other Ca(2+)-mediated electrophysiological responses are increased in hippocampus with aging, including Ca(2+) transients, L-type voltage-gated Ca(2+) channel activity, Ca(2+) spike duration and action potential accommodation. Elevated Ca(2+)-induced Ca(2+) release from ryanodine receptors (RyRs) appears to drive amplification of the Ca(2+) responses. Components of this Ca(2+) dysregulation phenotype correlate with deficits in cognitive function and plasticity, indicating they may play critical roles in aging-related impairment of brain function. However, the molecular mechanisms underlying aging-related Ca(2+) dysregulation are not well understood. FK506-binding proteins 1a and 1b (FKBP1a/1b, also known as FKBP12/12.6) are immunophilin proteins that bind the immunosuppressant drugs FK506 and rapamycin. In muscle cells, FKBP1a/1b also bind RyRs and inhibits Ca(2+)-induced Ca(2+) release, but it is not clear whether FKBPs act similarly in brain cells. Recently, we found that selectively disrupting hippocampal FKBP1b function in young rats, either by microinjecting adeno-associated viral vectors expressing siRNA, or by treatment with rapamycin, increases the sAHP and recapitulates much of the hippocampal Ca(2+) dysregulation phenotype. Moreover, in microarray studies, we found FKBP1b gene expression was downregulated in hippocampus of aging rats and early-stage Alzheimer's disease subjects. These results suggest the novel hypothesis that declining FKBP function is a key factor in aging-related Ca(2+) dysregulation in the brain and point to potential new therapeutic targets for counteracting unhealthy brain aging.
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Affiliation(s)
- J C Gant
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - E M Blalock
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - K-C Chen
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - I Kadish
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - N M Porter
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - C M Norris
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - O Thibault
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States
| | - P W Landfield
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, 800 Rose St., UKMC Lexington, KY 40536, United States.
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20
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Lansner A, Marklund P, Sikström S, Nilsson LG. Reactivation in working memory: an attractor network model of free recall. PLoS One 2013; 8:e73776. [PMID: 24023690 PMCID: PMC3758294 DOI: 10.1371/journal.pone.0073776] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 07/23/2013] [Indexed: 11/18/2022] Open
Abstract
The dynamic nature of human working memory, the general-purpose system for processing continuous input, while keeping no longer externally available information active in the background, is well captured in immediate free recall of supraspan word-lists. Free recall tasks produce several benchmark memory phenomena, like the U-shaped serial position curve, reflecting enhanced memory for early and late list items. To account for empirical data, including primacy and recency as well as contiguity effects, we propose here a neurobiologically based neural network model that unifies short- and long-term forms of memory and challenges both the standard view of working memory as persistent activity and dual-store accounts of free recall. Rapidly expressed and volatile synaptic plasticity, modulated intrinsic excitability, and spike-frequency adaptation are suggested as key cellular mechanisms underlying working memory encoding, reactivation and recall. Recent findings on the synaptic and molecular mechanisms behind early LTP and on spiking activity during delayed-match-to-sample tasks support this view.
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Affiliation(s)
- Anders Lansner
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
- School of Computer Science and Communication, Department of Computational Biology, KTH (Royal Institute of Technology), Stockholm, Sweden
- Stockholm Brain Institute, Stockholm, Sweden
| | - Petter Marklund
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Stockholm University, Stockholm, Sweden
| | - Sverker Sikström
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Lund University, Lund, Sweden
| | - Lars-Göran Nilsson
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Stockholm University, Stockholm, Sweden
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21
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Ferrarelli F, Smith R, Dentico D, Riedner BA, Zennig C, Benca RM, Lutz A, Davidson RJ, Tononi G. Experienced mindfulness meditators exhibit higher parietal-occipital EEG gamma activity during NREM sleep. PLoS One 2013; 8:e73417. [PMID: 24015304 PMCID: PMC3756031 DOI: 10.1371/journal.pone.0073417] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/22/2013] [Indexed: 11/18/2022] Open
Abstract
Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25–40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function.
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Affiliation(s)
- Fabio Ferrarelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Richard Smith
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniela Dentico
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Brady A. Riedner
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Corinna Zennig
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ruth M. Benca
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Antoine Lutz
- Waisman Center for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Lyon Neuroscience Research Center, Lyon 1 University, Lyon, France
| | - Richard J. Davidson
- Waisman Center for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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22
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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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23
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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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24
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Lu CB, Vreugdenhil M, Toescu EC. The effect of aging-associated impaired mitochondrial status on kainate-evoked hippocampal gamma oscillations. Neurobiol Aging 2012; 33:2692-703. [PMID: 22405041 PMCID: PMC3657166 DOI: 10.1016/j.neurobiolaging.2012.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 12/23/2011] [Accepted: 01/07/2012] [Indexed: 01/08/2023]
Abstract
Oscillations in hippocampal neuronal networks in the gamma frequency band have been implicated in various cognitive tasks and we showed previously that aging reduces the power of such oscillations. Here, using submerged hippocampal slices allowing simultaneous electrophysiological recordings and imaging, we studied the correlation between the kainate-evoked gamma oscillation and mitochondrial activity, as monitored by rhodamine 123. We show that the initiation of kainate-evoked gamma oscillations induces mitochondrial depolarization, indicating a metabolic response. Aging had an opposite effect on these parameters: while depressing the gamma oscillation strength, it increases mitochondrial depolarization. Also, in the aged neurons, kainate induced significantly larger Ca2+ signals. In younger slices, acute mitochondrial depolarization induced by low concentrations of mitochondrial protonophores strongly, but reversibly, inhibits gamma oscillations. These data indicating that the complex network activity required by the maintenance of gamma activity is susceptible to changes and modulations in mitochondrial status.
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Affiliation(s)
| | | | - Emil C. Toescu
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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25
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Engle JR, Barnes CA. Characterizing cognitive aging of associative memory in animal models. Front Aging Neurosci 2012; 4:10. [PMID: 22988435 PMCID: PMC3439635 DOI: 10.3389/fnagi.2012.00010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/14/2012] [Indexed: 12/18/2022] Open
Abstract
An overview is provided of the simple single-cue delay and trace eyeblink conditioning paradigms as techniques to assess associative learning and memory in the aged. We highlight and focus this review on the optimization of the parameter space of eyeblink conditioning designs in the aged to avoid and control for potential confounds that may arise when studying aged mammals. The need to examine the contribution of non-associative factors that can contribute to performance outcomes is emphasized, and how age-related changes in the central nervous system as well as peripheral sensory factors can potentially bias the interpretation of the data in the aged is discussed. The way in which slight alterations of the parameter space in the delay and trace eyeblink conditioning paradigms can lead to delayed but intact conditioning, rather than impaired performance in aged animals is also discussed. Overall, the eyeblink conditioning paradigm, when optimized for the age of the animal in the study, is an elegantly simple technique for assessment of associative learning and memory. When design caveats described above are taken into account, this important type of memory, with its well-defined neural substrates, should definitely be included in cognitive assessment batteries for the aged.
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Affiliation(s)
- James R Engle
- Evelyn F. McKnight Brain Institute and ARL Division of Neural Systems, Memory and Aging, University of Arizona Tucson, AZ, USA ; California National Primate Research Center Davis, CA, USA
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26
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Yeoman M, Scutt G, Faragher R. Insights into CNS ageing from animal models of senescence. Nat Rev Neurosci 2012; 13:435-45. [PMID: 22595787 DOI: 10.1038/nrn3230] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In recent years, novel model systems have made significant contributions to our understanding of the processes that control the ageing of whole organisms. However, there are limited data to show that the mechanisms that gerontologists have identified as having a role in organismal ageing contribute significantly to the ageing of the central nervous system. Two recent discoveries illustrate this particularly well. The first is the consistent failure of researchers to demonstrate a simple relationship between organismal ageing and oxidative stress--a mechanism often assumed to have a primary role in brain ageing. The second is the demonstration that senescent cells play a causal part in organismal ageing but remain essentially unstudied in a CNS context. We argue that the animal models now available (including rodents, flies, molluscs and worms), if properly applied, will allow a paradigm shift in our current understanding of the normal processes of brain ageing.
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Affiliation(s)
- Mark Yeoman
- School of Pharmacy and Biomolecular Sciences, Huxley Building, University of Brighton, Brighton, East Sussex BN2 4GJ, UK
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27
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Kumar A, Bodhinathan K, Foster TC. Susceptibility to Calcium Dysregulation during Brain Aging. Front Aging Neurosci 2009; 1:2. [PMID: 20552053 PMCID: PMC2874411 DOI: 10.3389/neuro.24.002.2009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 10/27/2009] [Indexed: 01/06/2023] Open
Abstract
Calcium (Ca(2+)) is a highly versatile intracellular signaling molecule that is essential for regulating a variety of cellular and physiological processes ranging from fertilization to programmed cell death. Research has provided ample evidence that brain aging is associated with altered Ca(2+) homeostasis. Much of the work has focused on the hippocampus, a brain region critically involved in learning and memory, which is particularly susceptible to dysfunction during senescence. The current review takes a broader perspective, assessing age-related changes in Ca(2+) sources, Ca(2+) sequestration, and Ca(2+) binding proteins throughout the nervous system. The nature of altered Ca(2+) homeostasis is cell specific and may represent a deficit or a compensatory mechanism, producing complex patterns of impaired cellular function. Incorporating the knowledge of the complexity of age-related alterations in Ca(2+) homeostasis will positively shape the development of highly effective therapeutics to treat brain disorders.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida Gainesville, FL, USA
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