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Navakkode S, Kennedy BK. Neural ageing and synaptic plasticity: prioritizing brain health in healthy longevity. Front Aging Neurosci 2024; 16:1428244. [PMID: 39161341 PMCID: PMC11330810 DOI: 10.3389/fnagi.2024.1428244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 07/24/2024] [Indexed: 08/21/2024] Open
Abstract
Ageing is characterized by a gradual decline in the efficiency of physiological functions and increased vulnerability to diseases. Ageing affects the entire body, including physical, mental, and social well-being, but its impact on the brain and cognition can have a particularly significant effect on an individual's overall quality of life. Therefore, enhancing lifespan and physical health in longevity studies will be incomplete if cognitive ageing is over looked. Promoting successful cognitive ageing encompasses the objectives of mitigating cognitive decline, as well as simultaneously enhancing brain function and cognitive reserve. Studies in both humans and animal models indicate that cognitive decline related to normal ageing and age-associated brain disorders are more likely linked to changes in synaptic connections that form the basis of learning and memory. This activity-dependent synaptic plasticity reorganises the structure and function of neurons not only to adapt to new environments, but also to remain robust and stable over time. Therefore, understanding the neural mechanisms that are responsible for age-related cognitive decline becomes increasingly important. In this review, we explore the multifaceted aspects of healthy brain ageing with emphasis on synaptic plasticity, its adaptive mechanisms and the various factors affecting the decline in cognitive functions during ageing. We will also explore the dynamic brain and neuroplasticity, and the role of lifestyle in shaping neuronal plasticity.
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Affiliation(s)
- Sheeja Navakkode
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, Centre for Healthy Longevity, National University Health System, National University of Singapore, Singapore, Singapore
- Life Sciences Institute Neurobiology Programme, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
| | - Brian K. Kennedy
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, Centre for Healthy Longevity, National University Health System, National University of Singapore, Singapore, Singapore
- Life Sciences Institute Neurobiology Programme, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Buck Institute for Research on Ageing, Novato, CA, United States
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Schrank S, Barrington N, Stutzmann GE. Calcium-Handling Defects and Neurodegenerative Disease. Cold Spring Harb Perspect Biol 2020; 12:a035212. [PMID: 31427373 PMCID: PMC7328457 DOI: 10.1101/cshperspect.a035212] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Calcium signaling is critical to neuronal function and regulates highly diverse processes such as gene transcription, energy production, protein handling, and synaptic structure and function. Because there are many common underlying calcium-mediated pathological features observed across several neurological conditions, it has been proposed that neurodegenerative diseases have an upstream underlying calcium basis in their pathogenesis. With certain diseases such as Alzheimer's, Parkinson's, and Huntington's, specific sources of calcium dysregulation originating from distinct neuronal compartments or channels have been shown to have defined roles in initiating or sustaining disease mechanisms. Herein, we will review the major hallmarks of these diseases, and how they relate to calcium dysregulation. We will then discuss neuronal calcium handling throughout the neuron, with special emphasis on channels involved in neurodegeneration.
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Affiliation(s)
- Sean Schrank
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
| | - Nikki Barrington
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
- Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois 60064
| | - Grace E Stutzmann
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
- Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois 60064
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3
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Maimaiti S, Frazier HN, Anderson KL, Ghoweri AO, Brewer LD, Porter NM, Thibault O. Novel calcium-related targets of insulin in hippocampal neurons. Neuroscience 2017; 364:130-142. [PMID: 28939258 DOI: 10.1016/j.neuroscience.2017.09.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 01/28/2023]
Abstract
Both insulin signaling disruption and Ca2+ dysregulation are closely related to memory loss during aging and increase the vulnerability to Alzheimer's disease (AD). In hippocampal neurons, aging-related changes in calcium regulatory pathways have been shown to lead to higher intracellular calcium levels and an increase in the Ca2+-dependent afterhyperpolarization (AHP), which is associated with cognitive decline. Recent studies suggest that insulin reduces the Ca2+-dependent AHP. Given the sensitivity of neurons to insulin and evidence that brain insulin signaling is reduced with age, insulin-mediated alterations in calcium homeostasis may underlie the beneficial actions of insulin in the brain. Indeed, increasing insulin signaling in the brain via intranasal delivery has yielded promising results such as improving memory in both clinical and animal studies. However, while several mechanisms have been proposed, few have focused on regulation on intracellular Ca2+. In the present study, we further examined the effects of acute insulin on calcium pathways in primary hippocampal neurons in culture. Using the whole-cell patch-clamp technique, we found that acute insulin delivery reduced voltage-gated calcium currents. Fura-2 imaging was used to also address acute insulin effects on spontaneous and depolarization-mediated Ca2+ transients. Results indicate that insulin reduced Ca2+ transients, which appears to have involved a reduction in ryanodine receptor function. Together, these results suggest insulin regulates pathways that control intracellular Ca2+ which may reduce the AHP and improve memory. This may be one mechanism contributing to improved memory recall in response to intranasal insulin therapy in the clinic.
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Affiliation(s)
- Shaniya Maimaiti
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Hilaree N Frazier
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Katie L Anderson
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Adam O Ghoweri
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Lawrence D Brewer
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Nada M Porter
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States
| | - Olivier Thibault
- Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, UKMC, MS-310; 800 Rose Street, Lexington, KY 40536, United States.
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4
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Lee E, Choi SY, Yang JH, Lee YJ. Preventive effects of imperatorin on perfluorohexanesulfonate-induced neuronal apoptosis via inhibition of intracellular calcium-mediated ERK pathway. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:399-406. [PMID: 27382356 PMCID: PMC4930908 DOI: 10.4196/kjpp.2016.20.4.399] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/23/2022]
Abstract
Early life neuronal exposure to environmental toxicants has been suggested to be an important etiology of neurodegenerative disease development. Perfluorohexanesulfonate (PFHxS), one of the major perfluoroalkyl compounds, is widely distributed environmental contaminants. We have reported that PFHxS induces neuronal apoptosis via ERK-mediated pathway. Imperatorin is a furanocoumarin found in various edible plants and has a wide range of pharmacological effects including neuroprotection. In this study, the effects of imperatorin on PFHxS-induced neuronal apoptosis and the underlying mechanisms are examined using cerebellar granule cells (CGC). CGC were isolated from seven-day old rats and were grown in culture for seven days. Caspase-3 activity and TUNEL staining were used to determine neuronal apoptosis. PFHxS-induced apoptosis of CGC was significantly reduced by imperatorin and PD98059, an ERK pathway inhibitor. PFHxS induced a persistent increase in intracellular calcium, which was significantly blocked by imperatorin, NMDA receptor antagonist, MK801 and the L-type voltage-dependent calcium channel blockers, diltiazem and nifedipine. The activation of caspase-3 by PFHxS was also inhibited by MK801, diltiazem and nifedipine. PFHxS-increased ERK activation was inhibited by imperatorin, MK801, diltiazem and nifedipine. Taken together, imperatorin protects CGC against PFHxS-induced apoptosis via inhibition of NMDA receptor/intracellular calcium-mediated ERK pathway.
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Affiliation(s)
- Eunkyung Lee
- Research and Development Division, Korea Promotion Institute for Traditional Medicine Industry, Gyeongsan 38540, Korea
| | - So-Young Choi
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu 42472, Korea
| | - Jae-Ho Yang
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu 42472, Korea
| | - Youn Ju Lee
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu 42472, Korea
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Lee YJ, Choi SY, Yang JH. AMP-activated protein kinase is involved in perfluorohexanesulfonate-induced apoptosis of neuronal cells. CHEMOSPHERE 2016; 149:1-7. [PMID: 26826296 DOI: 10.1016/j.chemosphere.2016.01.073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 11/24/2015] [Accepted: 01/18/2016] [Indexed: 06/05/2023]
Abstract
Perfluorohexanesulfonate (PFHxS), one of the major perfluoroalkyl compounds (PFCs), has been used in a variety of industrial and consumer applications and detected in serum in the general population. This raised a concern over its possible detrimental health effects, including neurotoxic effects. We have previously shown that PFHxS induced neuronal apoptosis via the NMDA receptor-mediated extracellular signal-regulated kinase (ERK) pathway. Recently, it has been reported that AMP-activated protein kinase (AMPK) acts as a key signal molecule in neuronal excitotoxicity as well as providing a neuroprotective function. In the present study, we have examined the involvement of AMPK in PFHxS-induced neuronal apoptosis using neuronal differentiated PC12 cells. PFHxS induced significant increases in intracellular [Ca(2+)] via the NMDA receptor and the L-type voltage-gated calcium channel (L-VGCC). The inhibition of Ca(2+) loading by the NMDA receptor antagonist, MK801 and the L-VGCC blockers, nifedipine and diltiazem significantly reduced PFHxS-induced apoptosis. PFHxS induced sustained activation of AMPK and the inhibition of AMPK activation by compound C and AMPK siRNA significantly reduced PFHxS-induced caspase-3 activity. These results indicate the pro-apoptotic role of AMPK. The activation of AMPK was attenuated by MK801, nifedipine and diltiazem. However, the activation of AMPK was not affected by the ERK inhibitor, PD98059. Likewise, ERK activation was not affected by compound C but was substantially reduced by MK801, nifedipine or diltiazem. This suggests that the activation of AMPK and ERK is regulated by intracellular Ca(2+) loading in distinct pathways. Taken together, PFHxS-induced neuronal apoptosis is mediated by AMPK and ERK pathways, which are distinctly regulated by increased intracellular Ca(2+) via the NMDA receptor and L-VGCC.
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Affiliation(s)
- Youn Ju Lee
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea
| | - So-Young Choi
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea
| | - Jae-Ho Yang
- Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea.
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Menzie J, Prentice H, Wu JY. Neuroprotective Mechanisms of Taurine against Ischemic Stroke. Brain Sci 2013; 3:877-907. [PMID: 24961429 PMCID: PMC4061860 DOI: 10.3390/brainsci3020877] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/14/2013] [Accepted: 05/17/2013] [Indexed: 02/02/2023] Open
Abstract
Ischemic stroke exhibits a multiplicity of pathophysiological mechanisms. To address the diverse pathophysiological mechanisms observed in ischemic stroke investigators seek to find therapeutic strategies that are multifaceted in their action by either investigating multipotential compounds or by using a combination of compounds. Taurine, an endogenous amino acid, exhibits a plethora of physiological functions. It exhibits antioxidative properties, stabilizes membrane, functions as an osmoregulator, modulates ionic movements, reduces the level of pro-inflammators, regulates intracellular calcium concentration; all of which contributes to its neuroprotective effect. Data are accumulating that show the neuroprotective mechanisms of taurine against stroke pathophysiology. In this review, we describe the neuroprotective mechanisms employed by taurine against ischemic stroke and its use in clinical trial for ischemic stroke.
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Affiliation(s)
- Janet Menzie
- Program in Integrative Biology, Florida Atlantic University, Boca Raton, FL 33431, USA.
| | - Howard Prentice
- Department of Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA.
| | - Jang-Yen Wu
- Program in Integrative Biology, Florida Atlantic University, Boca Raton, FL 33431, USA.
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7
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Sama DM, Mohmmad Abdul H, Furman JL, Artiushin IA, Szymkowski DE, Scheff SW, Norris CM. Inhibition of soluble tumor necrosis factor ameliorates synaptic alterations and Ca2+ dysregulation in aged rats. PLoS One 2012; 7:e38170. [PMID: 22666474 PMCID: PMC3362564 DOI: 10.1371/journal.pone.0038170] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/01/2012] [Indexed: 12/14/2022] Open
Abstract
The role of tumor necrosis factor α (TNF) in neural function has been investigated extensively in several neurodegenerative conditions, but rarely in brain aging, where cognitive and physiologic changes are milder and more variable. Here, we show that protein levels for TNF receptor 1 (TNFR1) are significantly elevated in the hippocampus relative to TNF receptor 2 (TNFR2) in aged (22 months) but not young adult (6 months) Fischer 344 rats. To determine if altered TNF/TNFR1 interactions contribute to key brain aging biomarkers, aged rats received chronic (4–6 week) intracranial infusions of XPro1595: a soluble dominant negative TNF that preferentially inhibits TNFR1 signaling. Aged rats treated with XPro1595 showed improved Morris Water Maze performance, reduced microglial activation, reduced susceptibility to hippocampal long-term depression, increased protein levels for the GluR1 type glutamate receptor, and lower L-type voltage sensitive Ca2+ channel (VSCC) activity in hippocampal CA1 neurons. The results suggest that diverse functional changes associated with brain aging may arise, in part, from selective alterations in TNF signaling.
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Affiliation(s)
- Diana M. Sama
- Graduate Center for Gerontology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Hafiz Mohmmad Abdul
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, United States of America
| | - Jennifer L. Furman
- Molecular & Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Irina A. Artiushin
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, United States of America
| | | | - Stephen W. Scheff
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, United States of America
- Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Christopher M. Norris
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, United States of America
- Molecular & Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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8
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Semaphorin3A facilitates axonal transport through a local calcium signaling and tetrodotoxin-sensitive voltage-gated sodium channels. Biochem Biophys Res Commun 2012; 422:333-8. [PMID: 22575508 DOI: 10.1016/j.bbrc.2012.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 05/01/2012] [Indexed: 12/16/2022]
Abstract
Semaphorin3A (Sema3A), a secreted factor that navigates axons and dendrites of developing neurons, facilitates axonal transport. However, little is known about the mechanism underlying Sema3A-induced facilitation and its functional implications. Here we show that Sema3A induces facilitation of axonal transport via local calcium signaling in growth cone. The facilitation of axonal transport was blocked by inhibitors of voltage-gated sodium channels (tetrodotoxin, TTX), L-type voltage-gated calcium channel, and ryanodine receptor (RyR). Sema3A evoked intracellular Ca(2+) elevation in growth cone by local application of Sema3A to growth cone. Sema3A also activated RyR in growth cone as well as cell body. Notably, TTX suppressed Sema3A-induced RyR activation in cell body but not in growth cone. Our results identify a novel mechanism of Sema3A-induced axonal transport, and further suggest that Sema3A-induced local calcium signaling in growth cone is propagated to cell body in a TTX-sensitive manner.
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Kim S, Yun HM, Baik JH, Chung KC, Nah SY, Rhim H. Functional interaction of neuronal Cav1.3 L-type calcium channel with ryanodine receptor type 2 in the rat hippocampus. J Biol Chem 2007; 282:32877-89. [PMID: 17823125 DOI: 10.1074/jbc.m701418200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal L-type Ca(2+) channels do not support synaptic transmission, but they play an essential role in synaptic activity-dependent gene expression. Ca(v)1.2 and Ca(v)1.3 are the two most widely expressed L-type Ca(2+) channels in neurons and have different biophysical and subcellular distributions. The function of the Ca(v) 1.3 L-type Ca(2+) channel and its cellular mechanisms in the central nervous system are poorly understood. In this study, using a yeast two-hybrid assay, we found that the N terminus of the rat Ca(v)1.3 alpha(1) subunit interacts with a partial N-terminal amino acid sequence of ryanodine receptor type 2 (RyR2). Reverse transcription-PCR and Western blot assays revealed high expression of both Ca(v)1.3 and RyR2 in the rat hippocampus. We also demonstrate a physical association of Ca(v)1.3 with RyR2 using co-immunoprecipitation assays. Moreover, immunocytochemistry revealed prominent co-localization between Ca(v)1.3 and RyR2 in hippocampal neurons. Depolarizing cells by an acute treatment of a high concentration of KCl (high-K, 60 mm) showed that the activation of L-type Ca(2+) channels induced RyR opening and led to RyR-dependent Ca(2+) release, even in the absence of extracellular Ca(2+). Furthermore, we found that RyR2 mRNA itself is increased by long term treatment of high-K via activation of L-type Ca(2+) channels. These acute and long term effects of high-K on RyRs were selectively blocked by small interfering RNA-mediated silencing of Ca(v)1.3. These results suggest a physical and functional interaction between Ca(v)1.3 and RyR2 and important implications of Ca(v)1.3/RyR2 clusters in translating synaptic activity into alterations in gene expression.
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Affiliation(s)
- Sunoh Kim
- Life Sciences Division, Korea Institute of Science and Technology, 39-1 Hawholgok-dong, Sungbuk-gu, Seoul, Korea
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10
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Thibault O, Gant JC, Landfield PW. Expansion of the calcium hypothesis of brain aging and Alzheimer's disease: minding the store. Aging Cell 2007; 6:307-17. [PMID: 17465978 PMCID: PMC1974776 DOI: 10.1111/j.1474-9726.2007.00295.x] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Evidence accumulated over more than two decades has implicated Ca2+ dysregulation in brain aging and Alzheimer's disease (AD), giving rise to the Ca2+ hypothesis of brain aging and dementia. Electrophysiological, imaging, and behavioral studies in hippocampal or cortical neurons of rodents and rabbits have revealed aging-related increases in the slow afterhyperpolarization, Ca2+ spikes and currents, Ca2+ transients, and L-type voltage-gated Ca2+ channel (L-VGCC) activity. Several of these changes have been associated with age-related deficits in learning or memory. Consequently, one version of the Ca2+ hypothesis has been that increased L-VGCC activity drives many of the other Ca2+-related biomarkers of hippocampal aging. In addition, other studies have reported aging- or AD model-related alterations in Ca2+ release from ryanodine receptors (RyR) on intracellular stores. The Ca2+-sensitive RyR channels amplify plasmalemmal Ca2+ influx by the mechanism of Ca2+-induced Ca2+ release (CICR). Considerable evidence indicates that a preferred functional link is present between L-VGCCs and RyRs which operate in series in heart and some brain cells. Here, we review studies implicating RyRs in altered Ca2+ regulation in cell toxicity, aging, and AD. A recent study from our laboratory showed that increased CICR plays a necessary role in the emergence of Ca2+-related biomarkers of aging. Consequently, we propose an expanded L-VGCC/Ca2+ hypothesis, in which aging/pathological changes occur in both L-type Ca2+ channels and RyRs, and interact to abnormally amplify Ca2+ transients. In turn, the increased transients result in dysregulation of multiple Ca2+-dependent processes and, through somewhat different pathways, in accelerated functional decline during aging and AD.
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Affiliation(s)
- Olivier Thibault
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, University of Kentucky Medical Center, Lexington, KY 40536, USA
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Brewer LD, Thibault O, Staton J, Thibault V, Rogers JT, Garcia-Ramos G, Kraner S, Landfield PW, Porter NM. Increased vulnerability of hippocampal neurons with age in culture: temporal association with increases in NMDA receptor current, NR2A subunit expression and recruitment of L-type calcium channels. Brain Res 2007; 1151:20-31. [PMID: 17433272 DOI: 10.1016/j.brainres.2007.03.020] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 02/24/2007] [Accepted: 03/05/2007] [Indexed: 11/20/2022]
Abstract
Excessive glutamate (Glu) stimulation of the NMDA-R is a widely recognized trigger for Ca(2+)-mediated excitotoxicity. Primary neurons typically show a large increase in vulnerability to excitotoxicity with increasing days in vitro (DIV). This enhanced vulnerability has been associated with increased expression of the NR2B subunit or increased NMDA-R current, but the detailed age-courses of these variables in primary hippocampal neurons have not been compared in the same study. Further, it is not clear whether the NMDA-R is the only source of excess Ca(2+). Here, we used primary hippocampal neurons to examine the age dependence of the increase in excitotoxic vulnerability with changes in NMDA-R current, and subunit expression. We also tested whether L-type voltage-gated Ca(2+) channels (L-VGCCs) contribute to the enhanced vulnerability. The EC(50) for Glu toxicity decreased by approximately 10-fold between 8-9 and 14-15 DIV, changing little thereafter. Parallel experiments found that during the same period both amplitude and duration of NMDA-R current increased dramatically; this was associated with an increase in protein expression of the NR1 and NR2A subunits, but not of the NR2B subunit. Compared to MK-801, ifenprodil, a selective NR2B antagonist, was less effective in protecting older than younger neurons from Glu insult. Conversely, nimodipine, an L-VGCC antagonist, protected older but not younger neurons. Our results indicate that enhanced excitotoxic vulnerability with age in culture was associated with a substantial increase in NMDA-R current, concomitant increases in NR2A and NR1 but not NR2B subunit expression, and with apparent recruitment of L-VGCCs into the excitotoxic process.
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Affiliation(s)
- Lawrence D Brewer
- Department of Molecular and Biomedical Pharmacology, Chandler Medical Center, University of Kentucky, Lexington, KY 40536-0298, USA
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12
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Isokawa M, Alger BE. Ryanodine Receptor Regulates Endogenous Cannabinoid Mobilization in the Hippocampus. J Neurophysiol 2006; 95:3001-11. [PMID: 16467427 DOI: 10.1152/jn.00975.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endogenous cannabinoids (eCBs) are produced and mobilized in a cytosolic calcium ([Ca2+]i)–dependent manner, and they regulate excitatory and inhibitory neurotransmitter release by acting as retrograde messengers. An indirect but real-time bioassay for this process on GABAergic transmission is DSI (depolarization-induced suppression of inhibition). The magnitude of DSI correlates linearly with depolarization-induced increase of [Ca2+]ithat is thought to be initiated by Ca2+influx through voltage-gated Ca2+channels. However, the identity of Ca2+sources involved in eCB mobilization in DSI remains undetermined. Here we show that, in CA1 pyramidal cells, DSI-inducing depolarizing voltage steps caused Ca2+-induced Ca2+release (CICR) by activating the ryanodine receptor (RyR) Ca2+-release channel. CICR was reduced, and the remaining increase in [Ca2+]iwas less effective in generating DSI, when the RyR antagonists, ryanodine or ruthenium red, were applied intracellularly, or the Ca2+stores were depleted by the Ca2+-ATPase inhibitors, cyclopiazonic acid or thapsigargin. The CICR-dependent effects were most prominent in cultured or immature acute slices, but were also detectable in slices from adult tissue. Thus we suggest that voltage-gated Ca2+entry raises local [Ca2+]isufficiently to activate nearby RyRs and that the resulting CICR plays a critical role in initiating eCB mobilization. RyR may be a key molecule for the depolarization-induced production of eCBs that inhibit GABA release in the hippocampus.
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Affiliation(s)
- Masako Isokawa
- Department of Physiology, University of Maryland, Baltimore, Maryland, USA.
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13
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Gant JC, Sama MM, Landfield PW, Thibault O. Early and simultaneous emergence of multiple hippocampal biomarkers of aging is mediated by Ca2+-induced Ca2+ release. J Neurosci 2006; 26:3482-90. [PMID: 16571755 PMCID: PMC6673869 DOI: 10.1523/jneurosci.4171-05.2006] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Age-dependent changes in multiple Ca2+-related electrophysiological processes in the hippocampus appear to be consistent biomarkers of aging, and several also correlate with cognitive decline. These findings have led to the hypothesis that a common mechanism of Ca2+ dyshomeostasis underlies aspects of aging-dependent brain impairment. However, some key predictions of this view remain untested, including that multiple Ca2+-related biomarkers should emerge concurrently during aging and their onset should also precede/coincide with initial signs of cognitive decline. Moreover, blocking a putative common source of dysregulated Ca2+ should eliminate aging differences. Here, we tested these predictions using combined electrophysiological, imaging, and pharmacological approaches in CA1 neurons to determine the ages of onset (across 4-, 10-, 12-, 14-, and 23-month-old F344 rats) of several established biomarkers, including the increases in the slow afterhyperpolarization, spike accommodation, and [Ca2+]i rise during repetitive synaptic stimulation. In addition, we tested the hypothesis that altered Ca2+-induced Ca2+ release (CICR) from ryanodine receptors, which can be triggered by L-type Ca2+ channels, provides a common source of dysregulated Ca2+ in aging. Results showed that multiple aging biomarkers were first detectable at about the same age (12 months of age; approximately midlife), sufficiently early to influence initial cognitive decline. Furthermore, selectively blocking CICR with ryanodine slowed the Ca2+ rise during synaptic stimulation more in aged rat neurons and, notably, reduced or eliminated aging differences in the biomarkers. Thus, this study provides the first evidence that altered CICR plays a role in driving the early and simultaneous emergence in hippocampus of multiple Ca2+-related biomarkers of aging.
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Verkhratsky A. Physiology and Pathophysiology of the Calcium Store in the Endoplasmic Reticulum of Neurons. Physiol Rev 2005; 85:201-79. [PMID: 15618481 DOI: 10.1152/physrev.00004.2004] [Citation(s) in RCA: 561] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is the largest single intracellular organelle, which is present in all types of nerve cells. The ER is an interconnected, internally continuous system of tubules and cisterns, which extends from the nuclear envelope to axons and presynaptic terminals, as well as to dendrites and dendritic spines. Ca2+release channels and Ca2+pumps residing in the ER membrane provide for its excitability. Regulated ER Ca2+release controls many neuronal functions, from plasmalemmal excitability to synaptic plasticity. Enzymatic cascades dependent on the Ca2+concentration in the ER lumen integrate rapid Ca2+signaling with long-lasting adaptive responses through modifications in protein synthesis and processing. Disruptions of ER Ca2+homeostasis are critically involved in various forms of neuropathology.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester, Faculty of Biological Sciences, United Kingdom.
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Lee SM, Lee JW, Song YS, Hwang DY, Kim YK, Nam SY, Kim DJ, Yun YW, Yoon DY, Hong JT. Ryanodine receptor-mediated interference of neuronal cell differentiation by presenilin 2 mutation. J Neurosci Res 2005; 82:542-50. [PMID: 16240390 DOI: 10.1002/jnr.20655] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neuronal cell differentiation alterations induced by mutant presenilin 2 (PS2) were investigated in transgenic mice expressing wild-type or mutant-type PS2. Progressive increases in differentiation and marker protein expression were found in neuronal cells expressing wild-type PS2, whereas these processes were much perturbed in mutant-type PS2 with elevated ryanodine-receptor (RyR) expression and intracellular calcium levels. Moreover, dantrolene, a blocker of RyR reduced the PS2 mutation-induced interference of cell differentiation and calcium release, but caffeine, an activator of RyR, exacerbated PS2 mutation-induced interference with cell differentiation. Our results indicate that mutant PS2 inhibits normal neuronal cell differentiation and that RyR-mediated calcium overrelease may be a significant factor.
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Affiliation(s)
- Sang Min Lee
- College of Pharmacy, Chungbuk National University, Chungbuk, Korea
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