101
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Kashiyae Y, Kontani M, Kawashima H, Kiso Y, Kudo Y, Sakakibara M. Arachidonic acid enhances intracellular calcium levels in dentate gyrus, but not CA1, in aged rat. Neurosci Res 2009; 64:143-51. [DOI: 10.1016/j.neures.2009.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 02/17/2009] [Accepted: 02/19/2009] [Indexed: 01/29/2023]
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102
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Abstract
An increase in L-type voltage-gated calcium channel (LTCC) current is a prominent biomarker of brain aging and is believed to contribute to cognitive decline and vulnerability to neuropathologies. Studies examining age-related changes in LTCCs have focused primarily on males, although estrogen (17beta-estradiol, E2) affects calcium-dependent activities associated with cognition. Therefore, to better understand brain aging in females, the effects of chronic E2 replacement on LTCC current activity in hippocampal neurons of young and aged ovariectomized rats were determined. The zipper slice preparation was used to expose cornu ammonis 1 (CA1) pyramidal neurons for recording LTCC currents using the cell-attached patch-clamp technique. We found that an age-related increase in LTCC current in neurons from control animals was prevented by E2 treatment. In addition, in situ hybridization revealed that within stratum pyramidale of the CA1 area, mRNA expression of the Ca(v)1.2 LTCC subunit, but not the Ca(v)1.3 subunit, was decreased in aged E2-treated rats. Thus, the reported benefits of E2 on cognition and neuronal health may be attributed, at least in part, to its age-related decrease in LTCC current.
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103
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Zhang XL, Gold MS. Dihydropyridine block of voltage-dependent K+ currents in rat dorsal root ganglion neurons. Neuroscience 2009; 161:184-94. [PMID: 19289157 DOI: 10.1016/j.neuroscience.2009.03.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/06/2009] [Accepted: 03/06/2009] [Indexed: 10/21/2022]
Abstract
The dihydropyridines nifedipine, nimodipine and Bay K 8644 are widely used as pharmacological tools to assess the contribution of L-type voltage-gated Ca(2+) channels to a variety of neuronal processes including synaptic transmission, excitability and second messenger signaling. These compounds are still used in neuronal preparations despite evidence from cardiac tissue and heterologous expression systems that they block several voltage-dependent K(+) (Kv) channels. Both because these compounds have been used to assess the relative contribution of L-type Ca(2+) channels to several different processes in dorsal root ganglion (DRG) neurons and because a relatively wide variety of Kv channels present in other neuronal populations is present in DRG neurons, we determined the extent to which dihydropyridines block Kv currents in these neurons. Standard whole cell patch clamp techniques were used to study acutely disassociated adult rat DRG neurons. All three dihydropyridines tested blocked Kv currents in DRG neurons; IC(50) values (concentration resulting in an inhibition that is 50% of maximum) for nifedipine and nimodipine-induced block of sustained Kv currents were 14.5 and 6.6 microM, respectively. The magnitude of sustained current block was 44+/-1.6%, 60+/-2%, and 56+/-2.9% with 10 microM nifedipine, nimodipine and Bay K 8644, respectively. Current block was occluded by neither 4-aminopyridine (5 mM) nor tetraethylammonium (135 mM). Dihydropyridine-induced block of Kv currents was not associated with a shift in the voltage-dependence of current activation or inactivation, the recovery from inactivation, or voltage dependent block. However, there was a small use-dependence to the dihydropyridine-induced block. Our results suggest that several types of Kv channels in DRG neurons are blocked by mechanisms distinct from those underlying block of Kv channels in cardiac myocytes. Importantly, our results suggest that if investigators wish to explore the contribution of L-type Ca(2+) channels to neuronal function, they should consider alternative strategies for the manipulation of these channels than the use of dihydropyridines.
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Affiliation(s)
- X-L Zhang
- Department of Anesthesiology, University of Pittsburgh, 3500 Terrace Street, Room E1440 BST, Pittsburgh, PA 15213, USA
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104
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Diguet E, Petit F, Escartin C, Cambon K, Bizat N, Dufour N, Hantraye P, Déglon N, Brouillet E. Normal aging modulates the neurotoxicity of mutant huntingtin. PLoS One 2009; 4:e4637. [PMID: 19247483 PMCID: PMC2645678 DOI: 10.1371/journal.pone.0004637] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 01/26/2009] [Indexed: 11/20/2022] Open
Abstract
Aging likely plays a role in neurodegenerative disorders. In Huntington's disease (HD), a disorder caused by an abnormal expansion of a polyglutamine tract in the protein huntingtin (Htt), the role of aging is unclear. For a given tract length, the probability of disease onset increases with age. There are mainly two hypotheses that could explain adult onset in HD: Either mutant Htt progressively produces cumulative defects over time or "normal" aging renders neurons more vulnerable to mutant Htt toxicity. In the present study, we directly explored whether aging affected the toxicity of mutant Htt in vivo. We studied the impact of aging on the effects produced by overexpression of an N-terminal fragment of mutant Htt, of wild-type Htt or of a beta-Galactosidase (beta-Gal) reporter gene in the rat striatum. Stereotaxic injections of lentiviral vectors were performed simultaneously in young (3 week) and old (15 month) rats. Histological evaluation at different time points after infection demonstrated that the expression of mutant Htt led to pathological changes that were more severe in old rats, including an increase in the number of small Htt-containing aggregates in the neuropil, a greater loss of DARPP-32 immunoreactivity and striatal neurons as assessed by unbiased stereological counts.The present results support the hypothesis that "normal" aging is involved in HD pathogenesis, and suggest that age-related cellular defects might constitute potential therapeutic targets for HD.
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Affiliation(s)
- Elsa Diguet
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Fanny Petit
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Carole Escartin
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Karine Cambon
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Nicolas Bizat
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Noëlle Dufour
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Philippe Hantraye
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Nicole Déglon
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
| | - Emmanuel Brouillet
- Commissariat à l'Energie Atomique (CEA), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), Orsay, France
- Centre National de la Recherche Scientifique (CNRS), Unité de Recherche Associée CEA-CNRS 2210, Orsay, France
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105
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Piacentini R, Ripoli C, Leone L, Misiti F, Clementi ME, D'Ascenzo M, Giardina B, Azzena GB, Grassi C. Role of methionine 35 in the intracellular Ca2+ homeostasis dysregulation and Ca2+-dependent apoptosis induced by amyloid beta-peptide in human neuroblastoma IMR32 cells. J Neurochem 2009; 107:1070-82. [PMID: 18990116 DOI: 10.1111/j.1471-4159.2008.05680.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Amyloid beta-peptide (Abeta) plays a fundamental role in the pathogenesis of Alzheimer's disease. We recently reported that the redox state of the methionine residue in position 35 of amyloid beta-peptide (Abeta) 1-42 (Met35) strongly affects the peptide's ability to trigger apoptosis and is thus a major determinant of its neurotoxicity. Dysregulation of intracellular Ca(2+) homeostasis resulting in the activation of pro-apoptotic pathways has been proposed as a mechanism underlying Abeta toxicity. Therefore, we investigated correlations between the Met35 redox state, Abeta toxicity, and altered intracellular Ca(2+) signaling in human neuroblastoma IMR32 cells. Cells incubated for 6-24 h with 10 microM Abeta1-42 exhibited significantly increased KCl-induced Ca(2+) transient amplitudes and resting free Ca(2+) concentrations. Nifedipine-sensitive Ca(2+) current densities and Ca(v)1 channel expression were markedly enhanced by Abeta1-42. None of these effects were observed when cells were exposed to Abeta containing oxidized Met35 (Abeta1-42(Met35-Ox)). Cell pre-treatment with the intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (1 microM) or the Ca(v)1 channel blocker nifedipine (5 microM) significantly attenuated Abeta1-42-induced apoptosis but had no effect on Abeta1-42(Met35-Ox) toxicity. Collectively, these data suggest that reduced Met35 plays a critical role in Abeta1-42 toxicity by rendering the peptide capable of disrupting intracellular Ca(2+) homeostasis and thereby provoking apoptotic cell death.
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Affiliation(s)
- Roberto Piacentini
- Institute of Human Physiology, Medical School, Catholic University S Cuore, Rome, Italy
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106
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Alonso MT, Manjarrés IM, García-Sancho J. Modulation of calcium signalling by intracellular organelles seen with targeted aequorins. Acta Physiol (Oxf) 2009; 195:37-49. [PMID: 18983457 DOI: 10.1111/j.1748-1716.2008.01920.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cytosolic Ca(2+) signals that trigger cell responses occur either as localized domains of high Ca(2+) concentration or as propagating Ca(2+) waves. Cytoplasmic organelles, taking up or releasing Ca(2+) to the cytosol, shape the cytosolic signals. On the other hand, Ca(2+) concentration inside organelles is also important in physiology and pathophysiology. Comprehensive study of these matters requires to measure [Ca(2+)] inside organelles and at the relevant cytosolic domains. Aequorins, the best-known chemiluminescent Ca(2+) probes, are excellent for this end as they do not require stressing illumination, have a large dynamic range and a sharp Ca(2+)-dependence, can be targeted to the appropriate location and engineered to have the proper Ca(2+) affinity. Using this methodology, we have evidenced the existence in chromaffin cells of functional units composed by three closely interrelated elements: (1) plasma membrane Ca(2+) channels, (2) subplasmalemmal endoplasmic reticulum and (3) mitochondria. These Ca(2+)-signalling triads optimize Ca(2+) microdomains for secretion and prevent propagation of the Ca(2+) wave towards the cell core. Oscillatory cytosolic Ca(2+) signals originate also oscillations of mitochondrial Ca(2+) in several cell types. The nuclear envelope slows down the propagation of the Ca(2+) wave to the nucleus and filters high frequencies. On the other hand, inositol-trisphosphate may produce direct release of Ca(2+) to the nucleoplasm in GH(3) pituitary cells, thus providing mechanisms for selective nuclear signalling. Aequorins emitting at different wavelengths, prepared by fusion either with green or red fluorescent protein, permit simultaneous and independent monitorization of the Ca(2+) signals in different subcellular domains within the same cell.
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Affiliation(s)
- M T Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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107
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Eto R, Abe M, Hayakawa N, Kato H, Araki T. Age-related changes of calcineurin and Akt1/protein kinase Balpha (Akt1/PKBalpha) immunoreactivity in the mouse hippocampal CA1 sector: an immunohistochemical study. Metab Brain Dis 2008; 23:399-409. [PMID: 18770014 DOI: 10.1007/s11011-008-9103-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Accepted: 07/18/2008] [Indexed: 11/26/2022]
Abstract
We investigated the age-related alterations of calcineurin and Akt1/protein kinase Balpha (Akt1/PKBalpha) immunoreactivity in the mouse hippocampal CA1 sector using immunohistochemistry. Calcineurin and Akt1/PKBalpha immunoreactivity was measured in 2-, 8-, 18-, 40-42- and 50-59-weeks-old animals. Diffuse calcineurin immunoreactivity was evident in pyramidal neurons of the hippocampal CA1 sector of 8-weeks-old mice. Densities of calcineurin immunoreactivity were lowered significantly in the hippocampal CA1 neurons of 2-weeks-old mice. In contrast, densities of calcineurin immunoreactivity were unchanged in the hippocampal CA1 neurons up to 40-42-weeks-old mice. However, densities of calcineurin immunoreactivity were increased significantly in the dendrites and plasma membranes of the hippocampal CA1 neurons of 50-59-weeks-old mice compared to 8-weeks old animals. Akt1/PKBalpha immunoreactivity was slightly detectable in the hippocampal CA1 sector of 8-weeks-old mice. A weak Akt1/PKBalpha immunoreactivity was found in cytoplasm of the hippocampal CA1 neurons and glial cells. Densities of Akt1/PKBalpha immunoreactivity were unchanged in the hippocampal CA1 neurons and glial cells of 2-weeks-old mice. In contrast, densities of Akt1/PKBalpha immunoreactivity were increased significantly in cytoplasm of neurons and glial cells of the hippocampal CA1 sector from 40-42 to 50-59 weeks after birth. The present study indicates that densities of calcineurin immunoreactivity and number of Akt1/PKBalpha immunoreactive cells were increased significantly in the hippocampal CA1 sector during aging processes. Our study also demonstrates that the activation of Akt1/PKBalpha signaling pathway may act defense mechanism against the neuronal dysfunction of the hippocampal CA1 sector caused by the activation of calcineurin signaling pathway during aging processes. These findings suggest that the calcineurin and Akt1/PKBalpha signaling pathway may be important targets for the development of novel therapeutic strategies for protection against age-related neurodegeneration.
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Affiliation(s)
- Risa Eto
- Department of Neurobiology and Therapeutics, Graduate School and Faculty of Pharmaceutical Sciences, The University of Tokushima, 1-78, Sho-machi, Tokushima, 770-8505, Japan
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108
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Endoh T, Sato D, Wada Y, Ishihara K, Hashimoto S, Yoshinari M, Matsuzaka K, Tazaki M, Inoue T. Nerve growth factor and brain-derived neurotrophic factor attenuate angiotensin-II-induced facilitation of calcium channels in acutely dissociated nucleus tractus solitarii neurons of the rat. Arch Oral Biol 2008; 53:1192-201. [DOI: 10.1016/j.archoralbio.2008.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 06/03/2008] [Accepted: 07/25/2008] [Indexed: 02/05/2023]
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109
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Li Z, Wright FA, Royland J. Age-dependent variability in gene expression in male Fischer 344 rat retina. Toxicol Sci 2008; 107:281-92. [PMID: 18936298 DOI: 10.1093/toxsci/kfn215] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Recent evidence suggests that older adults may be a sensitive population with regard to environmental exposure to toxic compounds. One source of this sensitivity could be an enhanced variability in response. Studies on phenotypic differences have suggested that variation in response does increase with age. However, few reports address the question of variation in gene expression as an underlying cause for increased variability of phenotypic response in the aged. In this study, we utilized global analysis to compare variation in constitutive gene expression in the retinae of young (4 months), middle-aged (11 months), and aged (23 months) Fischer 344 rats. Three hundred and forty transcripts were identified in which variance in expression increased from 4 to 23 months of age, while only 12 transcripts were found for which it decreased. Functional roles for identified genes were clustered in basic biological categories including cell communication, function, metabolism, and response to stimuli. Our data suggest that population stochastically induced variability should be considered in assessing sensitivity due to old age.
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Affiliation(s)
- Zhen Li
- Department of Biostatistics, Carolina Environmental Bioinformatics Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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110
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Brinton RD. Estrogen regulation of glucose metabolism and mitochondrial function: therapeutic implications for prevention of Alzheimer's disease. Adv Drug Deliv Rev 2008; 60:1504-11. [PMID: 18647624 PMCID: PMC2993571 DOI: 10.1016/j.addr.2008.06.003] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 06/12/2008] [Indexed: 02/06/2023]
Abstract
Estrogen-induced signaling pathways in hippocampal and cortical neurons converge upon the mitochondria to enhance mitochondrial function and to sustain aerobic glycolysis and citric acid cycle-driven oxidative phosphorylation and ATP generation. Data derived from experimental and clinical paradigms investigating estrogen intervention in healthy systems and prior to neurodegenerative insult indicate enhanced neural defense and survival through maintenance of calcium homeostasis, enhanced glycolysis coupled to the citric acid cycle (aerobic glycolysis), sustained and enhanced mitochondrial function, protection against free radical damage, efficient cholesterol trafficking and beta amyloid clearance. The convergence of E(2) mechanisms of action onto mitochondrial is also a potential point of vulnerability when activated in a degenerating neural system and could exacerbate the degenerative processes through increased load on dysregulated calcium homeostasis. The data indicate that as the continuum of neurological health progresses from healthy to unhealthy so too do the benefits of estrogen or hormone therapy. If neurons are healthy at the time of estrogen exposure, their response to estrogen is beneficial for both neuronal survival and neurological function. In contrast, if neurological health is compromised, estrogen exposure over time exacerbates neurological demise. The healthy cell bias of estrogen action hypothesis provides a lens through which to assess the disparities in outcomes across the basic to clinical domains of scientific inquiry and on which to predict future applications of estrogen and hormone therapeutic interventions sustain neurological health and to prevent age-associated neurodegenerative diseases such as Alzheimer's. Overall, E(2) promotes the energetic capacity of brain mitochondria by maximizing aerobic glycolysis (oxidative phosphorylation coupled to pyruvate metabolism). The enhanced aerobic glycolysis in the aging brain would be predicted to prevent conversion of the brain to using alternative sources of fuel such as the ketone body pathway characteristic of Alzheimer's.
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Affiliation(s)
- Roberta Diaz Brinton
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, School of Pharmacy Pharmaceutical Sciences Center, Los Angeles, California 90033, USA.
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111
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Brinton RD. The healthy cell bias of estrogen action: mitochondrial bioenergetics and neurological implications. Trends Neurosci 2008; 31:529-37. [PMID: 18774188 PMCID: PMC10124615 DOI: 10.1016/j.tins.2008.07.003] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 07/16/2008] [Accepted: 07/17/2008] [Indexed: 01/18/2023]
Abstract
The 'healthy cell bias of estrogen action' hypothesis examines the role that regulating mitochondrial function and bioenergetics play in promoting neural health and the mechanistic crossroads that lead to divergent outcomes following estrogen exposure. Estrogen-induced signaling pathways in hippocampal and cortical neurons converge upon the mitochondria to enhance aerobic glycolysis coupled to the citric acid cycle, mitochondrial respiration and ATP generation. Convergence of estrogen-induced signaling onto mitochondria is also a point of vulnerability when activated in diseased neurons which exacerbates degeneration through increased load on dysregulated calcium homeostasis. As the continuum of neurological health progresses from healthy to unhealthy so too do the benefits of estrogen or hormone therapy. The healthy cell bias of estrogen action hypothesis provides a lens through which to assess disparities in outcomes across basic and clinical science and on which to predict outcomes of estrogen interventions for sustaining neurological health and preventing age-associated neurodegenerative diseases such as Alzheimer's.
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Affiliation(s)
- Roberta Diaz Brinton
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, School of Pharmacy Pharmaceutical Sciences Center, Los Angeles, CA 90033, USA.
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112
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Abstract
Recent developments point to a critical role for calcium dysregulation in the pathogenesis of Alzheimer's disease. A novel calcium-conducting channel called CALHM1 is genetically linked to the disorder and modulates Abeta production. Calcium homeostasis has also been shown to be perturbed in dendritic spines adjacent to amyloid plaques. Finally, new studies have elucidated the role by which presenilins modulate calcium signaling, including effects on SERCA2b and gating of the IP(3) receptor, and lead to Abeta production.
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113
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Burke SN, Maurer AP, Yang Z, Navratilova Z, Barnes CA. Glutamate receptor-mediated restoration of experience-dependent place field expansion plasticity in aged rats. Behav Neurosci 2008; 122:535-48. [PMID: 18513124 DOI: 10.1037/0735-7044.122.3.535] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Place fields of hippocampal pyramidal cells expand asymmetrically when adult rats repeatedly follow the same route. This behaviorally induced expression of neuronal plasticity uses an NMDAR-dependent, LTP-like mechanism and could be used by hippocampal networks to store information. Aged spatial memory-impaired rats exhibit defective experience-dependent place field expansion plasticity. One possible explanation for this aged-associated deficit is alterations in glutamatergic function. In fact, both NMDAR- and AMPAR-mediated field excitatory postsynaptic potentials in CA1 decrease with aging. The current study investigated whether modulation of either AMPA or NDMA receptor activity could restore this experience-dependent plasticity by prolonging AMPAR activity with the ampakine CX516 and modulating the NMDAR with the noncompetitive antagonist memantine. The spatial firing characteristics of multiple CA1 pyramidal cells were monitored under both treatment conditions as aged rats repeatedly traversed a circular track. Compared to the saline baseline condition, acute administration of memantine, but not CX516, reinstated experience-dependent place field expansion. Taken together, these data suggest that pharmacological manipulation of the NMDAR can improve the function of hippocampal networks critical to optimal cognition in aging.
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Affiliation(s)
- Sara N Burke
- Evelyn F. McKnight Brain Institute, Life Sciences North Building, Room 384, University of Arizona, Tucson, AZ 85724, USA
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114
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Ouda L, Druga R, Syka J. Changes in parvalbumin immunoreactivity with aging in the central auditory system of the rat. Exp Gerontol 2008; 43:782-9. [DOI: 10.1016/j.exger.2008.04.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 03/21/2008] [Accepted: 04/01/2008] [Indexed: 10/22/2022]
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115
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Bezprozvanny I, Mattson MP. Neuronal calcium mishandling and the pathogenesis of Alzheimer's disease. Trends Neurosci 2008; 31:454-63. [PMID: 18675468 DOI: 10.1016/j.tins.2008.06.005] [Citation(s) in RCA: 656] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 12/23/2022]
Abstract
Perturbed neuronal Ca(2+) homeostasis is implicated in age-related cognitive impairment and Alzheimer's disease (AD). With advancing age, neurons encounter increased oxidative stress and impaired energy metabolism, which compromise the function of proteins that control membrane excitability and subcellular Ca(2+) dynamics. Toxic forms of amyloid beta-peptide (Abeta) can induce Ca(2+) influx into neurons by inducing membrane-associated oxidative stress or by forming an oligomeric pore in the membrane, thereby rendering neurons vulnerable to excitotoxicity and apoptosis. AD-causing mutations in the beta-amyloid precursor protein and presenilins can compromise these normal proteins in the plasma membrane and endoplasmic reticulum, respectively. Emerging knowledge of the actions of Ca(2+) upstream and downstream of Abeta provides opportunities to develop novel preventative and therapeutic interventions for AD.
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Affiliation(s)
- Ilya Bezprozvanny
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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116
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Sametsky EA, Disterhoft JF, Geinisman Y, Nicholson DA. Synaptic strength and postsynaptically silent synapses through advanced aging in rat hippocampal CA1 pyramidal neurons. Neurobiol Aging 2008; 31:813-25. [PMID: 18620783 DOI: 10.1016/j.neurobiolaging.2008.05.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 05/28/2008] [Accepted: 05/30/2008] [Indexed: 01/17/2023]
Abstract
Synaptic dysfunction is thought to contribute to age-related learning impairments. Detailed information regarding the presence of silent synapses and the strength of functional ones through advanced aging, however, is lacking. Here we used paired-pulse minimal stimulation techniques in CA1 stratum radiatum to determine whether the amplitude of spontaneous and evoked miniature excitatory postsynaptic currents (sEPSCs and eEPSCs, respectively) changes over the lifespan of rats in hippocampal CA1 pyramidal neurons, and whether silent synapses are present in adult and aged rats. The amplitudes of both sEPSCs and eEPSCs at resting membrane potential (i.e., clamped at -65 mV) initially increased between 2 weeks and 3 months, but then remained constant through 36 months of age. The potency of the eEPSCs at depolarized membrane potentials (i.e., clamped at +40 mV), however, was highest among 36-month old rats. Additionally, presynaptically silent synapses in CA1 stratum radiatum disappeared between 2 weeks and 3 months, but postsynaptically silent synapses were present through advanced aging. The similarity of silent and functional synapses in CA1 hippocampus at resting membrane potentials throughout adulthood in rats may indicate that impairments in the mechanisms of synaptic plasticity and its subsequent stabilization, rather than deficient synaptic transmission, underlie age-related cognitive decline. Such a notion is consistent with the increased amplitude of synaptic currents at depolarized potentials, perhaps suggesting an upregulation in the expression of synaptic NMDA receptors once rats reach advanced age.
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Affiliation(s)
- Evgeny A Sametsky
- Department of Physiology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
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117
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Burdakov D, Petersen OH, Verkhratsky A. Intraluminal calcium as a primary regulator of endoplasmic reticulum function. Cell Calcium 2008; 38:303-10. [PMID: 16076486 DOI: 10.1016/j.ceca.2005.06.010] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 01/11/2023]
Abstract
The concentration of Ca2+ inside the lumen of endoplasmic reticulum (ER) regulates a vast array of spatiotemporally distinct cellular processes, from intracellular Ca2+ signals to intra-ER protein processing and cell death. This review summarises recent data on the mechanisms of luminal Ca2+-dependent regulation of Ca2+ release and uptake as well as ER regulation of cellular adaptive processes. In addition we discuss general biophysical properties of the ER membrane, as trans-endomembrane Ca2+ fluxes are subject to basic electrical forces, determined by factors such as the membrane potential of the ER and the ease with which Ca2+ fluxes are able to change this potential (i.e. the resistance of the ER membrane). Although these electrical forces undoubtedly play a fundamental role in shaping [Ca2+](ER) dynamics, at present there is very little direct experimental information about the biophysical properties of the ER membrane. Further studies of how intraluminal [Ca2+] is regulated, best carried out with direct measurements, are vital for understanding how Ca2+ orchestrates cell function. Direct monitoring of [Ca2+](ER) under conditions where the cytosolic [Ca2+] is known may also help to capture elusive biophysical information about the ER, such as the potential difference across the ER membrane.
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Affiliation(s)
- Denis Burdakov
- Faculty of Life Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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118
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Poon IO. Effects of Antihypertensive Drug Treatment on the Risk of Dementia and Cognitive Impairment. Pharmacotherapy 2008; 28:366-75. [DOI: 10.1592/phco.28.3.366] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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119
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Piacentini R, Ripoli C, Mezzogori D, Azzena GB, Grassi C. Extremely low-frequency electromagnetic fields promote in vitro neurogenesis via upregulation of Ca(v)1-channel activity. J Cell Physiol 2008; 215:129-39. [PMID: 17941084 DOI: 10.1002/jcp.21293] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We previously reported that exposure to extremely low-frequency electromagnetic fields (ELFEFs) increases the expression and function of voltage-gated Ca2+)channels and that Ca2+ influx through Ca(v)1 channels plays a key role in promoting the neuronal differentiation of neural stem/progenitor cells (NSCs). The present study was conducted to determine whether ELFEFs influence the neuronal differentiation of NSCs isolated from the brain cortices of newborn mice by modulating Ca(v)1-channel function. In cultures of differentiating NSCs exposed to ELFEFs (1 mT, 50 Hz), the percentage of cells displaying immunoreactivity for neuronal markers (beta-III-tubulin, MAP2) and for Ca(v)1.2 and Ca(v)1.3 channels was markedly increased. NSC-differentiated neurons in ELFEF-exposed cultures also exhibited significant increases in spontaneous firing, in the percentage of cells exhibiting Ca2+ transients in response to KCl stimulation, in the amplitude of these transients and of Ca2+ currents generated by the activation of Ca(v)1 channels. When the Ca(v)1-channel blocker nifedipine (5 microM) was added to the culture medium, the neuronal yield of NSC differentiation dropped significantly, and ELFEF exposure no longer produced significant increases in beta-III-tubulin- and MAP2-immunoreactivity rates. In contrast, the effects of ELFEFs were preserved when NSCs were cultured in the presence of either glutamate receptor antagonists or Ca(v)2.1- and Ca(v)2.2-channel blockers. ELFEF stimulation during the first 24 h of differentiation caused Ca(v)1-dependent increases in the number of cells displaying CREB phosphorylation. Our data suggest that ELFEF exposure promotes neuronal differentiation of NSCs by upregulating Ca(v)1-channel expression and function.
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Affiliation(s)
- Roberto Piacentini
- Institute of Human Physiology, Medical School, Catholic University S. Cuore, Rome, Italy
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120
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Piacentini R, Gangitano C, Ceccariglia S, Fà AD, Azzena GB, Michetti F, Grassi C. Dysregulation of intracellular calcium homeostasis is responsible for neuronal death in an experimental model of selective hippocampal degeneration induced by trimethyltin. J Neurochem 2008; 105:2109-21. [DOI: 10.1111/j.1471-4159.2008.05297.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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121
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Benchoua A, Trioulier Y, Diguet E, Malgorn C, Gaillard MC, Dufour N, Elalouf JM, Krajewski S, Hantraye P, Déglon N, Brouillet E. Dopamine determines the vulnerability of striatal neurons to the N-terminal fragment of mutant huntingtin through the regulation of mitochondrial complex II. Hum Mol Genet 2008; 17:1446-56. [PMID: 18267960 PMCID: PMC2367694 DOI: 10.1093/hmg/ddn033] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In neurodegenerative disorders associated with primary or secondary mitochondrial defects such as Huntington's disease (HD), cells of the striatum are particularly vulnerable to cell death, although the mechanisms by which this cell death is induced are unclear. Dopamine, found in high concentrations in the striatum, may play a role in striatal cell death. We show that in primary striatal cultures, dopamine increases the toxicity of an N-terminal fragment of mutated huntingtin (Htt-171-82Q). Mitochondrial complex II protein (mCII) levels are reduced in HD striatum, indicating that this protein may be important for dopamine-mediated striatal cell death. We found that dopamine enhances the toxicity of the selective mCII inhibitor, 3-nitropropionic acid. We also demonstrated that dopamine doses that are insufficient to produce cell loss regulate mCII expression at the mRNA, protein and catalytic activity level. We also show that dopamine-induced down-regulation of mCII levels can be blocked by several dopamine D2 receptor antagonists. Sustained overexpression of mCII subunits using lentiviral vectors abrogated the effects of dopamine, both by high dopamine concentrations alone and neuronal death induced by low dopamine concentrations together with Htt-171-82Q. This novel pathway links dopamine signaling and regulation of mCII activity and could play a key role in oxidative energy metabolism and explain the vulnerability of the striatum in neurodegenerative diseases.
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Affiliation(s)
- Alexandra Benchoua
- Unité de Recherche Associée, Commissariat à l'Energie Atomique (CEA)-Centre Nationale de la Recherche Scientifique (CNRS) 2210, Service Hospitalier Frédéric Joliot, Orsay Cedex, France
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122
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Buga AM, Sascau M, Pisoschi C, Herndon JG, Kessler C, Popa-Wagner A. The genomic response of the ipsilateral and contralateral cortex to stroke in aged rats. J Cell Mol Med 2008; 12:2731-53. [PMID: 18266980 PMCID: PMC3828887 DOI: 10.1111/j.1582-4934.2008.00252.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Aged rats recover poorly after unilateral stroke, whereas young rats recover readily possibly with the help from the contralateral, healthy hemisphere. In this study we asked whether anomalous, age-related changes in the transcriptional activity in the brains of aged rats could be one underlying factor contributing to reduced functional recovery. We analysed gene expression in the periinfarct and contralateral areas of 3-month- and 18-month-old Sprague Dawley rats. Our experimental end-points were cDNA arrays containing genes related to hypoxia signalling, DNA damage and apoptosis, cellular response to injury, axonal damage and re-growth, cell lineage differentiation, dendritogenesis and neurogenesis. The major transcriptional events observed were: (i) Early up-regulation of DNA damage and down-regulation of anti-apoptosis-related genes in the periinfarct region of aged rats after stroke; (ii) Impaired neurogenesis in the periinfarct area, especially in aged rats; (iii) Impaired neurogenesis in the contralateral (unlesioned) hemisphere of both young and aged rats at all times after stroke and (iv) Marked up-regulation, in aged rats, of genes associated with inflammation and scar formation. These results were confirmed with quantitative real-time PCR. We conclude that reduced transcriptional activity in the healthy, contralateral hemisphere of aged rats in conjunction with an early up-regulation of DNA damage-related genes and pro-apoptotic genes and down-regulation of axono- and neurogenesis in the periinfarct area are likely to account for poor neurorehabilitation after stroke in old rats.
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Affiliation(s)
- A-M Buga
- Molecular Neurobiology Laboratory, Clinic of Neurology, University of Greifswald, Germany
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123
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García-Sancho J, Verkhratsky A. Cytoplasmic organelles determine complexity and specificity of calcium signalling in adrenal chromaffin cells. Acta Physiol (Oxf) 2008; 192:263-71. [PMID: 18021325 DOI: 10.1111/j.1748-1716.2007.01812.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Complex and coordinated fluctuations of intracellular free Ca2+ concentration ([Ca2+]c) regulate secretion of adrenaline from chromaffin cells. The physiologically relevant intracellular Ca2+ signals occur either as localized microdomains of high Ca2+ concentrations or as propagating Ca2+ waves, which give rise to global Ca2+ elevations. Intracellular organelles, the endoplasmic reticulum (ER), mitochondria and nuclear envelope, are endowed with powerful Ca2+ transport systems. Calcium uptake and Ca2+ release from these organelles determine the spatial and temporal parameters of Ca2+ signalling events. Furthermore, the ER and mitochondria form close relations with the sites of plasmalemmal Ca2+ entry, creating 'Ca2+ signalling triads' which act as elementary operational units, which regulate exocytosis. Ca2+ ions accumulating in the ER and mitochondria integrate exocytotic activity with energy production and protein synthesis.
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Affiliation(s)
- J García-Sancho
- Departamento de Fisiología, Facultad de Medicina, Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain.
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124
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Takeda A, Sakurada N, Kanno S, Ando M, Oku N. Vulnerability to Seizures Induced by Potassium Dyshomeostasis in the Hippocampus in Aged Rats. ACTA ACUST UNITED AC 2008. [DOI: 10.1248/jhs.54.37] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsushi Takeda
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Naomi Sakurada
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Shingo Kanno
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Masaki Ando
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Naoto Oku
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
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125
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Schram MT, Trompet S, Kamper AM, de Craen AJM, Hofman A, Euser SM, Breteler MMB, Westendorp RGJ. Serum calcium and cognitive function in old age. J Am Geriatr Soc 2007; 55:1786-92. [PMID: 17979900 DOI: 10.1111/j.1532-5415.2007.01418.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To determine whether serum calcium is associated with cognitive function in elderly individuals in the general population. DESIGN Prospective follow-up study of two independent, population-based cohorts. SETTING The Rotterdam Study (median follow-up 11 years) and the Leiden 85-plus Study (median follow-up 5 years). PARTICIPANTS Three thousand nine hundred ninety-four individuals, mean age 71, from the Rotterdam Study and 560 individuals, all aged 85, from the Leiden 85-plus Study. MEASUREMENTS Global cognitive function was assessed in both cohorts using the Mini-Mental State Examination; attention, psychomotor speed, and memory function were assessed in the Leiden 85-plus Study only. Linear regression and linear mixed models were used for statistical analyses. RESULTS In the Rotterdam Study, high serum calcium was associated with worse global cognitive function at baseline (P<.05) and a faster rate of decline in cognitive function during follow-up (P=.005) in individuals aged 75 and older but not in younger individuals. In the Leiden 85-plus Study, high serum calcium was associated with worse global cognitive function from age 85 through 90 (P<.001). This observation also held for the specific cognitive domains tested (all P<.01). These results did not change when individuals with serum calcium levels greater than normal (>2.55 mmol/L) were excluded from the analyses. CONCLUSION In the general population, high serum calcium levels are associated with faster decline in cognitive function over the age of 75.
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Affiliation(s)
- Miranda T Schram
- Department of Gerontology and Geriatrics, Leiden University Medical Centre, Leiden, The Netherlands
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126
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Crivello NA, Rosenberg IH, Shukitt-Hale B, Bielinski D, Dallal GE, Joseph JA. Aging modifies brain region-specific vulnerability to experimental oxidative stress induced by low dose hydrogen peroxide. AGE (DORDRECHT, NETHERLANDS) 2007; 29:191-203. [PMID: 19424838 PMCID: PMC2267029 DOI: 10.1007/s11357-007-9039-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Accepted: 08/24/2007] [Indexed: 05/27/2023]
Abstract
Our previous studies demonstrated a significant decline in brain function and behavior in Fischer 344 (F344) rats with age. The present study was designed to test the hypothesis that dysregulation in calcium homeostasis (as assessed through (45)Ca flux) may contribute to the increase in age-related vulnerability to oxidative stress in brain regions, and result in a deficit in behavior-mediated signaling. Crude membrane (P-2) and more purified synaptosomal fractions were isolated from the striatum, hippocampus, and frontal cortex of young (6 months) and old (22 months) F344 rats and were assessed for calcium flux and extracellular-regulated kinase activity 1 (ERK) under control and oxidative stress conditions induced by low dose hydrogen peroxide (final concentration 5 microM). The level of oxidative stress responses was monitored by measuring reactive oxygen species (ROS) and glutathione (GSH). The results showed a significant difference in oxidative stress responses between young and old rats in evaluated brain regions. Old rats showed higher sensitivity to oxidative stress than young rats. The present findings show the differential effects of oxidative stress on calcium flux in brain regions with age that are dependent upon the brain areas examined and the fraction assessed. The accumulation of ROS and the decrease in GSH in the frontal cortex were sufficient to decrease ERK activity in old rats. This is the first study, to our knowledge, that demonstrates age-related differential sensitivity to oxidative stress expressed as a function of behavior-mediated signaling and stress levels among different fractions isolated from brain regions controlling behavior.
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Affiliation(s)
- Natalia A Crivello
- Nutrition and Neurocognition Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
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127
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Pawlyk AC, Ferber M, Shah A, Pack AI, Naidoo N. Proteomic analysis of the effects and interactions of sleep deprivation and aging in mouse cerebral cortex. J Neurochem 2007; 103:2301-13. [DOI: 10.1111/j.1471-4159.2007.04949.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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128
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Green KN, Smith IF, Laferla FM. Role of calcium in the pathogenesis of Alzheimer's disease and transgenic models. Subcell Biochem 2007; 45:507-21. [PMID: 18193650 DOI: 10.1007/978-1-4020-6191-2_19] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the elderly that is characterized by memory loss. Neuropathologically, the AD brain is marked by an increased AP burden, hyperphosphorylated tau aggregates, synaptic loss, and inflammatory responses. Disturbances in calcium homeostasis are also one of the earliest molecular changes that occur in AD patients, alongside alterations in calcium-dependent enzymes in the post-mortem brain. The sum of these studies suggests that calcium dyshomeostasis is an integral part of the pathology, either influencing AP production, mediating its effects or both. Increasing evidence from in vitro studies demonstrates that the AP peptide could modulate a number of ion channels increasing calcium influx, including voltage-gated calcium and potassium channels, the NMDA receptor, the nicotinic receptor, as well as forming its own calcium-conducting pores. In vivo evidence has shown that A3 impairs both LTP and cognition, whereas all of these ion channels cluster at the synapse and underlie synaptic transmission and hence cognition. Here we consider the evidence that AP causes cognitive deficits through altering calcium homeostasis at the synapse, thus impairing synaptic transmission and LTP. Furthermore, this disruption appearr to occur without overt or extensive neuronal loss, as it is observed in transgenic mouse models of AD, but may contribute to the synaptic loss, which is an early event that correlates best with cognitive decline.
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Affiliation(s)
- K N Green
- Department of Neurobiology and Behavior, University of California, Irvine CA 92697-4545, USA
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129
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Abstract
Calcium signalling system controls majority of cellular reactions. Calcium signals occurring within tightly regulated temporal and spatial domains, govern a host of Ca2(+)-dependent enzymes, which in turn determine specified cellular responses. Generation of Ca2+ signals is achieved through coordinated activity of several families of Ca2+ channels and transporters differentially distributed between intracellular compartments. Cell damage induced by environmental insults or by overstimulation of physiological pathways results in pathological Ca2+ signals, which trigger necrotic or apoptotic cellular death.
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130
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Smith GS, Gunning-Dixon FM, Lotrich FE, Taylor WD, Evans JD. Translational research in late-life mood disorders: implications for future intervention and prevention research. Neuropsychopharmacology 2007; 32:1857-75. [PMID: 17327888 DOI: 10.1038/sj.npp.1301333] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Clinical and epidemiological studies have consistently observed the heterogeneous symptomatology and course of geriatric depression. Given the importance of genetic and environmental risk factors, aging processes, neurodegenerative and cerebrovascular disease processes, and medical comorbidity, the integration of basic and clinical neuroscience research approaches is critical for the understanding of the variability in illness course, as well as the development of prevention and intervention strategies that are more effective. These considerations were the impetus for a workshop, sponsored by the Geriatrics Research Branch in the Division of Adult Translational Research and Treatment Development of the National Institute of Mental Health that was held on September 7-8, 2005. The primary goal of the workshop was to bring together investigators in geriatric psychiatry research with researchers in specific topic areas outside of geriatric mental health to identify priority areas to advance translational research in geriatric depression. As described in this report, the workshop focused on a discussion of the development and application of integrative approaches combining genetics and neuroimaging methods to understand such complex issues as treatment response variability, the role of medical comorbidity in depression, and the potential overlap between depression and dementia. Future directions for integrative research were identified. Understanding the nature of geriatric depression requires the application of translational research and interdisciplinary research approaches. Geriatric depression could serve as a model for translational research integrating basic and clinical neuroscience approaches that would have implications for the study of other neuropsychiatric disorders.
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Affiliation(s)
- Gwenn S Smith
- PET Centre, Centre for Addiction and Mental Health, Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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131
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Driver JE, Racca C, Cunningham MO, Towers SK, Davies CH, Whittington MA, LeBeau FEN. Impairment of hippocampal gamma (γ)-frequency oscillations in vitro in mice overexpressing human amyloid precursor protein (APP). Eur J Neurosci 2007; 26:1280-8. [PMID: 17767505 DOI: 10.1111/j.1460-9568.2007.05705.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease is associated with a dramatic decline in cognitive performance including hippocampal-dependent memory. We have investigated one feature of hippocampal activity related to memory, the gamma (30-80 Hz)-frequency rhythm. Hippocampal slices from mice overexpressing the human amyloid precursor protein (APP)(SWE) mutation (TAS10) were compared at 8 and 16 months of age with wild-type littermates. In slices obtained from TAS10 mice aged 8 months the gamma-frequency activity evoked with bath application of 200 nm kainate was significantly (P < 0.05; n = 8 slices, five animals) impaired (area power, 5956 +/- 2487 microV(2)) compared to slices from wild-type animals (area power, 18 256 +/- 7880 microV(2)). At 16 months of age there was no longer a significant difference (P > 0.05; n = 11 slices from five animals) between slices from TAS10 and wild-type control mice as the wild-type mice now exhibited a marked age-dependent reduction in gamma-frequency activity (TAS10 area power, 5751 +/- 1573 microV(2); wild-type area power = 5379 +/- 1454 microV(2)). Although no dense-core plaques were evident at 8 months there was detectable amyloid labelling in the TAS10 mice which might account for the deficits in gamma activity observed at this age. Dense plaques were clearly evident in the TAS10, but not wild-type, mice at 16 months of age but no further reductions in gamma-frequency activity were seen in the TAS10 mice. These data suggest that deficits in network function in Alzheimer's disease occur early and are not directly correlated to amyloid load.
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Affiliation(s)
- Joanne E Driver
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JP, UK
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132
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Murchison D, Griffith WH. Calcium buffering systems and calcium signaling in aged rat basal forebrain neurons. Aging Cell 2007; 6:297-305. [PMID: 17517040 PMCID: PMC2810842 DOI: 10.1111/j.1474-9726.2007.00293.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Disturbances of neuronal Ca2+ homeostasis are considered to be important determinants of age-related cognitive impairment. Cholinergic neurons of the basal forebrain (BF) are principal targets of decline associated with aging and dementia. During the last several years, we have attempted to link these concepts in a rat model of 'normal' aging. In this review, we will describe some changes that we have observed in Ca2+ signaling of aged BF neurons and the reversal of one of these changes by dietary caloric restriction. Our evidence supports a scenario in which subtle changes in the properties of voltage-gated Ca2+ channels result in increased Ca2+ influx during aging. This increased Ca2+, in turn, triggers an increase in rapid Ca2+ buffering in the somatic compartment of aged BF neurons. However, this nominal 'compensation', along with other changes in Ca2+ handling machinery (notably mitochondria) alters the Ca2+ signal with age in a way that is dependent on the magnitude of the Ca2+ load. By combining whole-cell patch clamp electrophysiology, ratiometric Ca2+-sensitive microfluorimetry and single-cell reverse transcription-polymerase chain reaction, we have determined that age-related rapid buffering changes are present in identified cholinergic BF neurons and that these changes can be prevented by a caloric restriction dietary regimen. Because caloric restriction extends lifespan and retards the progression of age-related dysfunction, these findings suggest that increased Ca2+ buffering in cholinergic neurons may be relevant to cognitive decline during normal aging. Importantly, calcium homeostatic mechanisms of BF cholinergic neurons are amenable to dietary interventions that could promote cognitive health during aging.
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Affiliation(s)
- David Murchison
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA
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133
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Toescu EC, Verkhratsky A. The importance of being subtle: small changes in calcium homeostasis control cognitive decline in normal aging. Aging Cell 2007; 6:267-73. [PMID: 17517038 DOI: 10.1111/j.1474-9726.2007.00296.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Aging is a complex, multifactorial process. One of the features of normal aging of the brain is a decline in cognitive functions and much experimental attention has been devoted to understanding this process. Evidence accumulated in the last decade indicates that such functional changes are not due to gross morphological alterations, but to subtle functional modification of synaptic connectivity and intracellular signalling and metabolism. Such synaptic modifications are compatible with a normal level of activity and allow the maintenance of a certain degree of functional reserve. This is in contrast to the changes in various neurodegenerative diseases, characterized by significant neuronal loss and dramatic and irreversible functional deficit. This whole special issue has been initiated with the intention of focusing on the processes of normal brain aging. In this review, we present data that shows how subtle changes in Ca(2+) homeostasis or in the state of various Ca(2+)-dependent processes or molecules, which occur in aging can have significant functional consequences.
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Affiliation(s)
- Emil C Toescu
- Department of Physiology, Division of Medical Sciences, The Medical School, University of Birmingham, Birmingham B15 2TT, UK.
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134
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Rose GM, Ong VS, Woodruff-Pak DS. Efficacy of MEM 1003, a novel calcium channel blocker, in delay and trace eyeblink conditioning in older rabbits. Neurobiol Aging 2007; 28:766-73. [PMID: 16621170 DOI: 10.1016/j.neurobiolaging.2006.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 02/10/2006] [Accepted: 03/14/2006] [Indexed: 11/22/2022]
Abstract
Eyeblink conditioning is a relatively simple form of associative learning that shows neurobiological and behavioral parallels across several species, including humans. Aged subjects acquire eyeblink conditioning more slowly than young ones. In addition, eyeblink conditioning effectively discriminates patients with Alzheimer's disease from healthy older adults. The present study evaluated the effect of a novel L-type Ca2+ channel antagonist, MEM 1003, on delay and trace eyeblink conditioning in older (mean 33.4 months old) female New Zealand white rabbits. In the delay conditioning paradigm, an 850 ms tone conditioning stimulus (CS) was followed 750 ms after its onset by a 100 ms corneal air puff. Several trace conditioning paradigms were evaluated, with a silent period of 300, 400 or 500 ms between the end of the tone CS and the delivery of the air puff. Learning was more difficult in the longer trace paradigms than in the delay paradigm. MEM 1003, at a dose of 2.0 mg/kg, s.c., given daily 30 min prior to training on each of the 15 training days, enhanced learning compared to vehicle injections in both delay and trace paradigms. However, higher or lower doses were ineffective. These results support previous work demonstrating that modulation of Ca2+ channel activity can reduce age-related cognitive impairments.
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Affiliation(s)
- Gregory M Rose
- Memory Pharmaceuticals Corp., Montvale, NJ, United States.
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135
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Luin E, Ruzzier F. The role of L- and T-type Ca2+ currents during the in vitro aging of murine myogenic (i28) cells in culture. Cell Calcium 2007; 41:479-89. [PMID: 17064763 DOI: 10.1016/j.ceca.2006.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 07/28/2006] [Accepted: 09/10/2006] [Indexed: 01/29/2023]
Abstract
The age-related decline in skeletal muscle strength could, in part, result from alterations in the mechanism of excitation-contraction coupling, responsible for muscle contraction. In the present work, we used the in vitro aging of murine myogenic (i28) cells as a model, to investigate whether the inefficiency of aged satellite cells to generate functional skeletal muscle fibres could be partly due to defective voltage-dependent Ca2+ currents. The whole-cell patch clamp technique was employed to measure L- and T-type Ca2+ currents in myotubes derived from the differentiation and fusion of these cells reaching replicative senescence. Our data showed that the expression and the amplitude of these currents decreased significantly during in vitro aging. Moreover, the analysis of the L-type current evoked in young and old cells by positive voltage steps, revealed no differences in the kinetics of activation, but significant alterations in the rate of inactivation. These effects of in vitro aging on voltage-dependent Ca2+ currents could also be related to their inability to fuse into myotubes. Taken together, our data support the hypothesis that age-related effects on voltage-dependent L- and T-type currents could be one of the causes of the failure of satellite cells to efficiently counteract the impairment in muscle force.
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Affiliation(s)
- Elisa Luin
- Department of Physiology and Pathology and Centre for Neuroscience BRAIN, University of Trieste, Via A. Fleming 22, I-34127 Trieste, Italy.
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136
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Mora F, Segovia G, del Arco A. Aging, plasticity and environmental enrichment: structural changes and neurotransmitter dynamics in several areas of the brain. ACTA ACUST UNITED AC 2007; 55:78-88. [PMID: 17561265 DOI: 10.1016/j.brainresrev.2007.03.011] [Citation(s) in RCA: 281] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/19/2007] [Accepted: 03/19/2007] [Indexed: 12/11/2022]
Abstract
Cajal was probably the first neurobiologist to suggest that plasticity of nerve cells almost completely disappeared during aging. However, we know today that neural plasticity is still present in the brain during aging. In this review we suggest that aging is a physiological process that occurs asynchronously in different areas of the brain and that the rate of that process is modulated by environmental factors and related to the neuronal-synaptic-molecular substrates of each area. We review here some of the most recent results on aging of the brain in relation to the plastic changes that occur in young and aged animals as a result of living in an enriched environment. We highlight the results from our own laboratory on the dynamics of neurotransmitters in different areas of the brain. Specifically we review first the effects of aging on neurons, dendrites, synapses, and also on molecular and functional plasticity. Second, the effects of environmental enrichment on the brain of young and aged animals. And third the effects of an enriched environment on the age-related changes in neurogenesis and in the extracellular concentrations of glutamate and GABA in hippocampus, and on dopamine, acetylcholine, glutamate and GABA under a situation of acute mild stress in the prefrontal cortex.
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Affiliation(s)
- Francisco Mora
- Department of Physiology, Faculty of Medicine, Universidad Complutense, Ciudad Universitaria, s/n, 28040 Madrid, Spain.
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137
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Beramendi A, Peron S, Casanova G, Reggiani C, Cantera R. Neuromuscular junction in abdominal muscles ofDrosophila melanogasterduring adulthood and aging. J Comp Neurol 2007; 501:498-508. [PMID: 17278125 DOI: 10.1002/cne.21253] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The neuromuscular junction (NMJ) of Drosophila melanogaster has been established as a productive model for the study of synaptogenesis, synaptic plasticity, vesicle recycling, and other synaptic functions in embryos and larvae. It also has potential for the study of long-term plasticity during adult life and degenerative processes associated with aging. Here we provide a detailed description of the morphology and ultrastructure of the NMJ on abdominal dorsal longitudinal muscles throughout adult life from eclosion to senescence. In contrast to the case in the larva, the predominant type of terminals in these muscles in the adult fly consists of only two or three branches with tightly packed synaptic boutons. We observed qualitative and quantitative changes as mean bouton size increased gradually during adulthood, and the largest boutons were present in the old fly. The length of nerve branches first increased and thereafter decreased gradually during most of adult life. Branch diameter also decreased progressively, but branch number did not change. The subsynaptic reticulum became progressively thinner, and "naked" boutons were found in old flies. Ultrastructural traits gave indications of an age-associated increment in autophagy, larger synaptic vesicles, and impaired endocytosis. We propose that NMJ aging in the fly correlates with impaired endocytosis and membrane dynamics. This view finds a functional correlate in flies carrying a temperature-sensitive mutation in shibire that reversible blocks endocytosis; age significantly reduces the time required for complete paralysis and increases the time of recovery, thus confirming the age-dependent alteration in vesicle dynamics.
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Affiliation(s)
- Ana Beramendi
- Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden 35131
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138
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Alonso G, Sanchez-Hormigo A, Loudes C, El Yandouzi T, Carmignac D, Faivre-Bauman A, Recolin B, Epelbaum J, Robinson ICAF, Mollard P, Méry PF. Selective alteration at the growth-hormone- releasing-hormone nerve terminals during aging in GHRH-green fluorescent protein mice. Aging Cell 2007; 6:197-207. [PMID: 17328688 DOI: 10.1111/j.1474-9726.2007.00276.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Growth hormone (GH) secretion decreases spontaneously during lifespan, and the resulting GH deficiency participates in aging-related morbidity. This deficiency appears to involve a defect in the activity of hypothalamic GH-releasing hormone (GHRH) neurons. Here, we investigated this hypothesis, as well as the underlying mechanisms, in identified GHRH neurons from adult ( approximately 13 weeks old) and aged ( approximately 100 weeks old) transgenic GHRH-green fluorescent protein mice, using morphological, biochemical and electrophysiological methods. Surprisingly, the spontaneous action potential frequency was similar in adult and aged GHRH neurons studied in brain slices. This was explained by a lack of change in the intrinsic excitability, and simultaneous increases in both stimulatory glutamatergic- and inhibitory GABAergic-synaptic currents of aged GHRH neurons. Aging did not decrease GHRH and enhanced green fluorescent protein contents, GHRH neuronal number or GHRH-fibre distribution, but we found a striking enlargement of GHRH-positive axons, suggesting neuropeptide accumulation. Unlike in adults, autophagic vacuoles were evident in aged GHRH-axonal profiles using electron microscopy. Thus, GHRH neurons are involved in aging of the GH axis. Aging had a subtle effect at the nerve terminal level in GHRH neurons, contrasting with the view that neuronal aging is accompanied by more widespread damage.
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Affiliation(s)
- Gérard Alonso
- Département d'Endocrinologie, Institut de Génomique Fonctionnelle, INSERM U661, CNRS UMR 5203, Université Montpellier 1 et 2, Montpellier, France
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139
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Chen GH, Wang YJ, Qin S, Yang QG, Zhou JN, Liu RY. Age-related spatial cognitive impairment is correlated with increase of synaptotagmin 1 in dorsal hippocampus in SAMP8 mice. Neurobiol Aging 2007; 28:611-8. [PMID: 16677738 DOI: 10.1016/j.neurobiolaging.2006.03.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 02/28/2006] [Accepted: 03/03/2006] [Indexed: 11/29/2022]
Abstract
The age-related decline of learning and memory is a common phenomenon in humans and animals, even though the underlying mechanism is not yet known. In the present study, we propose that synaptotagmin 1 (Syt 1) might be a synaptic protein involved in the loss of learning and memory with aging. To test this hypothesis, the age-related spatial cognitive ability of 36 P8 mice (15 mice aged 4 months, 11 mice aged 8 months and 10 mice aged 13 months) was measured in a Morris water maze. After the behavioral test, both the protein and mRNA levels of Syt 1 were determined in the dorsal hippocampus by means of immunocytochemistry and reverse transcriptase polymerase chain reaction (RT-PCR), respectively. In the Morris water maze, the latency of the 4-month mice to find the submerged platform was significantly shorter than that of the older mice, while there were no significant differences between the 8- and 13-month-old mice in this respect. Compared to the 4-month-old mice, the Syt 1 protein in the 13-month-old mice was significantly increased in almost all layers of each subfield of the hippocampus. The average level of Syt 1 mRNA in the dorsal hippocampus of the P8 mice had not changed with aging. The latency of the 13-month-old P8 mice tested in the Morris water maze was positively correlated with the Syt 1 immunoreactivity in four circuit-specific regions in the dorsal hippocampus. Interestingly, the latency in the Morris water maze was also positively correlated with the level of Syt 1 mRNA in the dorsal hippocampus in individual aged P8 mouse. These results suggest that increased Syt 1 in the dorsal hippocampus in aged mice might be responsible for the age-related impairment of learning and memory.
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Affiliation(s)
- Gui-Hai Chen
- Department of Neurology, Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, PR China
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140
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Jurkovicova D, Kopacek J, Stefanik P, Kubovcakova L, Zahradnikova A, Zahradnikova A, Pastorekova S, Krizanova O. Hypoxia modulates gene expression of IP3 receptors in rodent cerebellum. Pflugers Arch 2007; 454:415-25. [PMID: 17285299 DOI: 10.1007/s00424-007-0214-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 11/14/2006] [Accepted: 01/11/2007] [Indexed: 01/09/2023]
Abstract
Hypoxic brain cell injury is a complex process that results from a series of intracellular events. In this work, we tested whether severe hypoxia for 6 h can affect gene expression and protein levels of intracellular calcium channels, ryanodine receptors, and inositol 1,4,5-trisphosphate receptors in mouse cerebellum. In addition, we tested the effect of hypoxia on cerebellar granular cells of rats. We have found that gene expression of types 1 and 2 IP(3) receptors is significantly increased after the exposure of mice to hypoxic stimulus for 6 h and also in rat cerebellar granular cells. Increased gene expression of IP(3) receptors was reflected in increased protein levels of these channels as well. In this process, reactive oxygen species are most probably involved, as antioxidant quercetin abolished hypoxia-induced increase in both types 1 and 2 IP3 receptor. Ryanodine receptors of types 1 and 2 and sarco(endo)plasmic reticulum Ca(2+)-ATPase were not affected by hypoxia on the level of messenger RNA. To test physiological consequences, we measured levels of intracellular calcium. We observed significantly elevated calcium level in hypoxic compared to normoxic cells. Deeper understanding of mechanisms, through which hypoxia regulates intracellular calcium, could point towards the development of new therapeutic approaches to reduce or suppress the pathological effects of cellular hypoxia, such as those seen in stroke or ischemia.
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MESH Headings
- Animals
- Base Sequence
- Cells, Cultured
- Cerebellum/metabolism
- DNA Primers/genetics
- Female
- Gene Expression
- Hypoxia, Brain/genetics
- Hypoxia, Brain/metabolism
- Immunohistochemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Fluorescence
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
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Affiliation(s)
- D Jurkovicova
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlarska 5, 833 34, Bratislava, Slovakia
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141
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Copanaki E, Schürmann T, Eckert A, Leuner K, Müller WE, Prehn JHM, Kögel D. The amyloid precursor protein potentiates CHOP induction and cell death in response to ER Ca2+ depletion. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:157-65. [PMID: 17113167 DOI: 10.1016/j.bbamcr.2006.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 09/20/2006] [Accepted: 10/10/2006] [Indexed: 11/17/2022]
Abstract
Here we investigated the role of the amyloid precursor protein (APP) in regulation of Ca(2+) store depletion-induced neural cell death. Ca(2+) store depletion from the endoplasmic reticulum (ER) was induced by the SERCA (Sarco/Endoplasmic Reticulum Calcium ATPase) inhibitor thapsigargin which led to a rapid induction of the unfolded protein response (UPR) and a delayed activation of executioner caspases in the cultures. Overexpression of APP potently enhanced cytosolic Ca(2+) levels and cell death after ER Ca(2+) store depletion in comparison to vector-transfected controls. GeneChip and RT-PCR analysis revealed that the expression of classical UPR chaperone genes was not altered by overexpression of APP. Interestingly, the induction of the ER stress-responsive pro-apoptotic transcription factor CHOP was significantly upregulated in APP-overexpressing cells in comparison to vector-transfected controls. Chelation of intracellular Ca(2+) with BAPTA-AM revealed that enhanced CHOP expression after store depletion occurred in a Ca(2+)-dependent manner in APP-overexpressing cells. Prevention of CHOP induction by BAPTA-AM and by RNA interference was also able to abrogate the potentiating effect of APP on thapsigargin-induced apoptosis. Application of the store-operated channel (SOC)-inhibitors SK & F96365 and 2-APB downmodulated APP-triggered potentiation of cytosolic Ca(2+) levels and apoptosis after treatment with thapsigargin. Our data demonstrate that APP significantly modulates Ca(2+) store depletion-induced cell death in a SOC- and CHOP-dependent manner, but independent of the UPR.
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Affiliation(s)
- Ekaterini Copanaki
- Department of Neurosurgery, Johann Wolfgang Goethe University Clinics, D-60590 Frankfurt, Germany
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142
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Shen H, Zhang B, Shin JH, Lei D, Du Y, Gao X, Wang Q, Ohlemiller KK, Piccirillo J, Bao J. Prophylactic and therapeutic functions of T-type calcium blockers against noise-induced hearing loss. Hear Res 2006; 226:52-60. [PMID: 17291698 PMCID: PMC1903349 DOI: 10.1016/j.heares.2006.12.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 12/21/2006] [Accepted: 12/23/2006] [Indexed: 11/16/2022]
Abstract
Cochlear noise injury is the second most frequent cause of sensorineural hearing loss, after aging. Because calcium dysregulation is a widely recognized contributor to noise injury, we examined the potential of calcium channel blockers to reduce noise-induced hearing loss (NIHL) in mice. We focused on two T-type calcium blockers, trimethadione and ethosuximide, which are anti-epileptics approved by the Food and Drug Administration. Young C57BL/6 mice of either gender were divided into three groups: a 'prevention' group receiving the blocker via drinking water before noise exposure; a 'treatment' group receiving the blocker via drinking water after noise exposure; and controls receiving noise alone. Trimethadione significantly reduced NIHL when applied before noise exposure, as determined by auditory brainstem recording. Both ethosuximide and trimethadione were effective in reducing NIHL when applied after noise exposure. Results were influenced by gender, with males generally receiving greater benefit than females. Quantitation of hair cell and neuronal density suggested that preservation of outer hair cells could account for the observed protection. Immunocytochemistry and RT-PCR suggested that this protection involves direct action of T-type blockers on alpha1 subunits comprising one or more Ca(v)3 calcium channel types in the cochlea. Our findings provide a basis for clinical studies testing T-type calcium blockers both to prevent and treat NIHL.
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Affiliation(s)
- Haiyan Shen
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Baoping Zhang
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - June-Ho Shin
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Debin Lei
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Yafei Du
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Xiang Gao
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Qiuju Wang
- Department of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, P.R. China, 100853
| | - Kevin K. Ohlemiller
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jay Piccirillo
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jianxin Bao
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- **Corresponding Author: Jianxin Bao, Ph.D. Department of Otolaryngology, Washington University, 4560 Clayton Avenue, St. Louis, MO 63110, 314-747-7199, 314-747-7230 (fax),
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143
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Murphy GG, Rahnama NP, Silva AJ. Investigation of age-related cognitive decline using mice as a model system: behavioral correlates. Am J Geriatr Psychiatry 2006; 14:1004-11. [PMID: 17138807 DOI: 10.1097/01.jgp.0000209405.27548.7b] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE With recent advances in molecular genetics, mouse models have been generated for a number of disease states. Recently, the authors and others have begun to examine normal age-related cognitive decline using mice as a model system. In this article, and the companion article that follows, the authors present data intended to better parameterize the aging phenotype in mice and examine the possible underlying neuronal mechanisms with special emphasis on age-related changes in calcium homeostasis. METHODS Young (4-6-month-old) and aged (22-24-month-old) C57BL/6 mice were analyzed in terms of their spatial learning abilities in the hidden platform version of the Morris water maze and the delay win-shift version of the Olton radial arm maze. RESULTS Although aged mice exhibited cognitive impairments in both behavioral tasks used, the extent of impairment differed between the two tasks, which might prove to be advantageous under certain experimental settings. CONCLUSIONS Like in other areas of biomedical research, mice have become an invaluable research tool in the investigation of learning and memory. It is expected that similar benefits can be realized by developing mouse models for age-related cognitive decline.
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Affiliation(s)
- Geoffrey G Murphy
- Department of Neurobiology, Brain Research Institute, University of California, Los Angeles, CA 90095-1761, USA
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144
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Trompet S, Westendorp RGJ, Kamper AM, de Craen AJM. Use of calcium antagonists and cognitive decline in old age. The Leiden 85-plus study. Neurobiol Aging 2006; 29:306-8. [PMID: 17101196 DOI: 10.1016/j.neurobiolaging.2006.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2006] [Revised: 09/16/2006] [Accepted: 10/07/2006] [Indexed: 10/23/2022]
Abstract
The systolic hypertension in Europe (Syst-Eur) trial has been the only trial that has suggested a protective effect of antihypertensive treatment on incidence of dementia. It is unclear whether this protective effect has been caused by the blood pressure lowering effect of the calcium antagonist nitrendipine or by the calcium channel inhibition. From the Leiden 85-plus study, a population-based cohort study of 599 subjects aged 85 years, we selected 204 subjects who used at least one antihypertensive at baseline. Associations between use of antihypertensives at baseline and change in cognitive functioning over time were assessed with linear mixed models. After adjusting for gender, education, and use of other antihypertensives, only use of calcium antagonists was associated with a significant decelerated annual cognitive decline during follow-up (0.40 MMSE-points per year, p=0.001). Use of other antihypertensives was not associated with a decelerated annual cognitive decline (all p values >0.3). Our data support the interpretation that the reported prevention of dementia by calcium antagonists is exerted through its calcium channel inhibition rather than its blood pressure lowering properties.
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Affiliation(s)
- Stella Trompet
- Department of Gerontology and Geriatrics, Leiden University Medical Center, The Netherlands
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145
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Brewer LD, Porter NM, Kerr DS, Landfield PW, Thibault O. Chronic 1α,25-(OH)2vitamin D3 treatment reduces Ca2+-mediated hippocampal biomarkers of aging. Cell Calcium 2006; 40:277-86. [PMID: 16780945 DOI: 10.1016/j.ceca.2006.04.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Accepted: 04/21/2006] [Indexed: 10/24/2022]
Abstract
Aging in the hippocampus of several species is characterized by alterations in multiple Ca(2+)-mediated processes, including an increase in L-type voltage-gated Ca(2+) channel (L-VGCC) current, an enhanced Ca(2+)-dependent slow afterhyperpolarization (AHP), impaired synaptic plasticity and elevated Ca(2+) transients. Previously, we found that 1alpha,25-dihydoxyvitamin D(3) (1,25VitD), a major Ca(2+) regulating hormone, down-regulates L-VGCC expression in cultured hippocampal neurons. Here, we tested whether in vivo treatment of aged F344 rats with 1,25VitD would reverse some of the Ca(2+) -mediated biomarkers of aging seen in hippocampal CA1 neurons. As previously reported, L-VGCC currents and the AHP were larger in aged than in young neurons. Treatment with 1,25VitD over 7 days decreased L-VGCC activity in aged rats, as well as the age-related increase in AHP amplitude and duration. In addition, reduced L-VGCC activity was correlated with reduced AHPs in the same animals. These data provide direct evidence that 1,25VitD can regulate multiple Ca(2+)-dependent processes in neurons, with particular impact on reducing age-related changes associated with Ca(2+) dysregulation. Thus, these results may have therapeutic implications and suggest that 1,25VitD, often taken to maintain bone health, may also retard some consequences of brain aging.
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Affiliation(s)
- Lawrence D Brewer
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 800 Rose Street, MS-310, University of Kentucky Medical Center, Lexington, 40536-0298, USA
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146
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Norris CM, Blalock EM, Thibault O, Brewer LD, Clodfelter GV, Porter NM, Landfield PW. Electrophysiological mechanisms of delayed excitotoxicity: positive feedback loop between NMDA receptor current and depolarization-mediated glutamate release. J Neurophysiol 2006; 96:2488-500. [PMID: 16914613 PMCID: PMC2756090 DOI: 10.1152/jn.00593.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Delayed excitotoxic neuronal death after insult from exposure to high glutamate concentrations appears important in several CNS disorders. Although delayed excitotoxicity is known to depend on NMDA receptor (NMDAR) activity and Ca(2+) elevation, the electrophysiological mechanisms underlying postinsult persistence of NMDAR activation are not well understood. Membrane depolarization and nonspecific cationic current in the postinsult period were reported previously, but were not sensitive to NMDAR antagonists. Here, we analyzed mechanisms of the postinsult period using parallel current- and voltage-clamp recording and Ca(2+) imaging in primary hippocampal cultured neurons. We also compared more vulnerable older neurons [about 22 days in vitro (DIV)] to more resistant younger (about 15 DIV) neurons, to identify processes selectively associated with cell death in older neurons. During exposure to a modest glutamate insult (20 microM, 5 min), similar degrees of Ca(2+) elevation, membrane depolarization, action potential block, and increased inward current occurred in younger and older neurons. However, after glutamate withdrawal, these processes recovered rapidly in younger but not in older neurons. The latter also exhibited a concurrent postinsult increase in spontaneous miniature excitatory postsynaptic currents, reflecting glutamate release. Importantly, postinsult NMDAR antagonist administration reversed all of these persisting responses in older cells. Conversely, repolarization of the membrane by voltage clamp immediately after glutamate exposure reversed the NMDAR-dependent Ca(2+) elevation. Together, these data suggest that, in vulnerable neurons, excitotoxic insult induces a sustained positive feedback loop between NMDAR-dependent current and depolarization-mediated glutamate release, which persists after withdrawal of exogenous glutamate and drives Ca(2+) elevation and delayed excitotoxicity.
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Affiliation(s)
- C M Norris
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, MS-305, UKMC, Lexington, KY 40536-0298, USA
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147
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Abstract
Calcium ions are the most ubiquitous and pluripotent cellular signaling molecules that control a wide variety of cellular processes. The calcium signaling system is represented by a relatively limited number of highly conserved transporters and channels, which execute Ca2+ movements across biological membranes and by many thousands of Ca2+-sensitive effectors. Molecular cascades, responsible for the generation of calcium signals, are tightly controlled by Ca2+ ions themselves and by genetic factors, which tune the expression of different Ca2+-handling molecules according to adaptational requirements. Ca2+ ions determine normal physiological reactions and the development of many pathological processes.
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148
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Abstract
Normal ageing is associated with a degree of decline in a number of cognitive functions. Apart from the issues raised by the current attempts to expand the lifespan, understanding the mechanisms and the detailed metabolic interactions involved in the process of normal neuronal ageing continues to be a challenge. One model, supported by a significant amount of experimental evidence, views the cellular ageing as a metabolic state characterized by an altered function of the metabolic triad: mitochondria-reactive oxygen species (ROS)-intracellular Ca2+. The perturbation in the relationship between the members of this metabolic triad generate a state of decreased homeostatic reserve, in which the aged neurons could maintain adequate function during normal activity, as demonstrated by the fact that normal ageing is not associated with widespread neuronal loss, but become increasingly vulnerable to the effects of excessive metabolic loads, usually associated with trauma, ischaemia or neurodegenerative processes. This review will concentrate on some of the evidence showing altered mitochondrial function with ageing and also discuss some of the functional consequences that would result from such events, such as alterations in mitochondrial Ca2+ homeostasis, ATP production and generation of ROS.
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Affiliation(s)
- Emil C Toescu
- Division of Medical Sciences, University of Birmingham Department of Physiology Edgbaston, Birmingham B15 2TT, UK.
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149
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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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150
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Abstract
Everyone ages, but only some will develop a neurodegenerative disorder in the process. Disease might occur when cells fail to respond adaptively to age-related increases in oxidative, metabolic and ionic stress, thereby resulting in the accumulation of damaged proteins, DNA and membranes. Determinants of neuronal vulnerability might include cell size and location, metabolism of disease-specific proteins and a repertoire of signal transduction pathways and stress resistance mechanisms. Emerging evidence on protein interaction networks that monitor and respond to the normal ageing process suggests that successful neural ageing is possible for most people, but also cautions that cures for neurodegenerative disorders are unlikely in the near future.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland 21224-6825, USA.
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