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de Veij Mestdagh CF, Smit AB, Henning RH, van Kesteren RE. Mitochondrial Targeting against Alzheimer's Disease: Lessons from Hibernation. Cells 2023; 13:12. [PMID: 38201215 PMCID: PMC10778235 DOI: 10.3390/cells13010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia worldwide and yet remains without effective therapy. Amongst the many proposed causes of AD, the mitochondrial cascade hypothesis is gaining attention. Accumulating evidence shows that mitochondrial dysfunction is a driving force behind synaptic dysfunction and cognitive decline in AD patients. However, therapies targeting the mitochondria in AD have proven unsuccessful so far, and out-of-the-box options, such as hibernation-derived mitochondrial mechanisms, may provide valuable new insights. Hibernators uniquely and rapidly alternate between suppression and re-activation of the mitochondria while maintaining a sufficient energy supply and without acquiring ROS damage. Here, we briefly give an overview of mitochondrial dysfunction in AD, how it affects synaptic function, and why mitochondrial targeting in AD has remained unsuccessful so far. We then discuss mitochondria in hibernation and daily torpor in mice, covering current advancements in hibernation-derived mitochondrial targeting strategies. We conclude with new ideas on how hibernation-derived dual mitochondrial targeting of both the ATP and ROS pathways may boost mitochondrial health and induce local synaptic protein translation to increase synaptic function and plasticity. Further exploration of these mechanisms may provide more effective treatment options for AD in the future.
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Affiliation(s)
- Christina F. de Veij Mestdagh
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; (A.B.S.); (R.E.v.K.)
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands;
- Alzheimer Center Amsterdam, Amsterdam UMC Location VUmc, 1081 HV Amsterdam, The Netherlands
| | - August B. Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; (A.B.S.); (R.E.v.K.)
| | - Robert H. Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands;
| | - Ronald E. van Kesteren
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; (A.B.S.); (R.E.v.K.)
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2
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Song Z, Griesser M, Schuppli C, van Schaik CP. Does the expensive brain hypothesis apply to amphibians and reptiles? BMC Ecol Evol 2023; 23:77. [PMID: 38114918 PMCID: PMC10729550 DOI: 10.1186/s12862-023-02188-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 12/09/2023] [Indexed: 12/21/2023] Open
Abstract
Vertebrate brains show extensive variation in relative size. The expensive brain hypothesis argues that one important source of this variation is linked to a species' ability to generate the energy required to sustain the brain, especially during periods of unavoidable food scarcity. Here we ask whether this hypothesis, tested so far in endothermic vertebrates, also applies to ectotherms, where ambient temperature is an additional major aspect of energy balance. Phylogenetic comparative analyses of reptiles and amphibians support the hypothesis. First, relative brain size increases with higher body temperature in those species active during the day that can gain free energy by basking. Second, relative brain size is smaller among nocturnal species, which generally face less favorable energy budgets, especially when maintaining high body temperature. However, we do not find an effect of seasonal variation in ambient temperature or food on brain size, unlike in endotherms. We conclude that the factors affecting energy balance in ectotherms and endotherms are overlapping but not identical. We therefore discuss the idea that when body temperatures are seasonally very low, cognitive benefits may be thwarted and selection on larger brain size may be rare. Indeed, mammalian hibernators may show similarities to ectotherms.
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Affiliation(s)
- Zitan Song
- Comparative Socioecology group, Department for the Ecology of Animal Societies, Max Planck Institute for Animal Behavior, 78467, Konstanz, Germany.
| | - Michael Griesser
- Department of Biology, University of Konstanz, 78467, Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78467, Konstanz, Germany
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, 78467, Konstanz, Germany
| | - Caroline Schuppli
- Development and Evolution of Cognition Group, Max Planck Institute for Animal Behavior, 78467, Konstanz, Germany
| | - Carel P van Schaik
- Comparative Socioecology group, Department for the Ecology of Animal Societies, Max Planck Institute for Animal Behavior, 78467, Konstanz, Germany
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, 8057, Switzerland
- Center for the Interdisciplinary Study of language Evolution, University of Zurich, Zurich, 8057, Switzerland
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3
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The molecular memory code and synaptic plasticity: A synthesis. Biosystems 2023; 224:104825. [PMID: 36610586 DOI: 10.1016/j.biosystems.2022.104825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/29/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023]
Abstract
The most widely accepted view of memory in the brain holds that synapses are the storage sites of memory, and that memories are formed through associative modification of synapses. This view has been challenged on conceptual and empirical grounds. As an alternative, it has been proposed that molecules within the cell body are the storage sites of memory, and that memories are formed through biochemical operations on these molecules. This paper proposes a synthesis of these two views, grounded in a computational model of memory. Synapses are conceived as storage sites for the parameters of an approximate posterior probability distribution over latent causes. Intracellular molecules are conceived as storage sites for the parameters of a generative model. The model stipulates how these two components work together as part of an integrated algorithm for learning and inference.
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Heck N, Santos MD. Dendritic Spines in Learning and Memory: From First Discoveries to Current Insights. ADVANCES IN NEUROBIOLOGY 2023; 34:311-348. [PMID: 37962799 DOI: 10.1007/978-3-031-36159-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The central nervous system is composed of neural ensembles, and their activity patterns are neural correlates of cognitive functions. Those ensembles are networks of neurons connected to each other by synapses. Most neurons integrate synaptic signal through a remarkable subcellular structure called spine. Dendritic spines are protrusions whose diverse shapes make them appear as a specific neuronal compartment, and they have been the focus of studies for more than a century. Soon after their first description by Ramón y Cajal, it has been hypothesized that spine morphological changes could modify neuronal connectivity and sustain cognitive abilities. Later studies demonstrated that changes in spine density and morphology occurred in experience-dependent plasticity during development, and in clinical cases of mental retardation. This gave ground for the assumption that dendritic spines are the particular locus of cerebral plasticity. With the discovery of synaptic long-term potentiation, a research program emerged with the aim to establish whether dendritic spine plasticity could explain learning and memory. The development of live imaging methods revealed on the one hand that dendritic spine remodeling is compatible with learning process and, on the other hand, that their long-term stability is compatible with lifelong memories. Furthermore, the study of the mechanisms of spine growth and maintenance shed new light on the rules of plasticity. In behavioral paradigms of memory, spine formation or elimination and morphological changes were found to correlate with learning. In a last critical step, recent experiments have provided evidence that dendritic spines play a causal role in learning and memory.
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Affiliation(s)
- Nicolas Heck
- Laboratory Neurosciences Paris Seine, Sorbonne Université, Paris, France.
| | - Marc Dos Santos
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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5
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Rasia-Filho AA, Calcagnotto ME, von Bohlen Und Halbach O. Introduction: What Are Dendritic Spines? ADVANCES IN NEUROBIOLOGY 2023; 34:1-68. [PMID: 37962793 DOI: 10.1007/978-3-031-36159-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Dendritic spines are cellular specializations that greatly increase the connectivity of neurons and modulate the "weight" of most postsynaptic excitatory potentials. Spines are found in very diverse animal species providing neural networks with a high integrative and computational possibility and plasticity, enabling the perception of sensorial stimuli and the elaboration of a myriad of behavioral displays, including emotional processing, memory, and learning. Humans have trillions of spines in the cerebral cortex, and these spines in a continuum of shapes and sizes can integrate the features that differ our brain from other species. In this chapter, we describe (1) the discovery of these small neuronal protrusions and the search for the biological meaning of dendritic spines; (2) the heterogeneity of shapes and sizes of spines, whose structure and composition are associated with the fine-tuning of synaptic processing in each nervous area, as well as the findings that support the role of dendritic spines in increasing the wiring of neural circuits and their functions; and (3) within the intraspine microenvironment, the integration and activation of signaling biochemical pathways, the compartmentalization of molecules or their spreading outside the spine, and the biophysical properties that can affect parent dendrites. We also provide (4) examples of plasticity involving dendritic spines and neural circuits relevant to species survival and comment on (5) current research advancements and challenges in this exciting research field.
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Affiliation(s)
- Alberto A Rasia-Filho
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Maria Elisa Calcagnotto
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Department of Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Psychiatry and Behavioral Science, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Dutton M, Can AT, Lagopoulos J, Hermens DF. Stress, mental disorder and ketamine as a novel, rapid acting treatment. Eur Neuropsychopharmacol 2022; 65:15-29. [PMID: 36206584 DOI: 10.1016/j.euroneuro.2022.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/09/2022] [Accepted: 09/17/2022] [Indexed: 12/13/2022]
Abstract
The experience of stress is often utilised in models of emerging mental illness and neurobiological systems are implicated as the intermediary link between the experience of psychological stress and the development of a mental disorder. Chronic stress and prolonged glucocorticoid exposure have potent effects on neuronal architecture particularly in regions that modulate the hypothalamic-pituitary-adrenal (HPA) axis and are commonly associated with psychiatric disorders. This review provides an overview of stress modulating neurobiological and neurochemical systems which underpin stress-related structural and functional brain changes. These changes are thought to contribute not only to the development of disorders, but also to the treatment resistance and chronicity seen in some of our most challenging mental disorders. Reports to date suggest that stress-related psychopathology is the aetiological mechanism of these disorders and thus we review the rapid acting antidepressant ketamine as an effective emerging treatment. Ketamine, an N-methyl D-aspartate (NMDA) receptor antagonist, is shown to induce a robust treatment effect in mental disorders via enhanced synaptic strength and connectivity in key brain regions. Whilst ketamine's glutamatergic effect has been previously examined, we further consider ketamine's capacity to modulate the HPA axis and associated pathways.
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Affiliation(s)
- Megan Dutton
- Thompson Institute, University of the Sunshine Coast, 12 Innovation Parkway, Birtinya, Queensland 4575, Australia.
| | - Adem T Can
- Thompson Institute, University of the Sunshine Coast, 12 Innovation Parkway, Birtinya, Queensland 4575, Australia
| | - Jim Lagopoulos
- Thompson Institute, University of the Sunshine Coast, 12 Innovation Parkway, Birtinya, Queensland 4575, Australia
| | - Daniel F Hermens
- Thompson Institute, University of the Sunshine Coast, 12 Innovation Parkway, Birtinya, Queensland 4575, Australia
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7
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Seasonal differences in the morphology and spine density of hippocampal neurons in wild ground squirrels. Brain Struct Funct 2022; 227:2349-2365. [DOI: 10.1007/s00429-022-02528-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 06/17/2022] [Indexed: 11/02/2022]
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8
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Hensleigh E, Murtishaw AS, Treat MD, Heaney CF, Bolton MM, Sabbagh JJ, Calvin KN, Kinney JW, Breukelen FV. Torpor does not influence spatial memory in hibernating golden-mantled ground squirrels (Spermophilus [Callospermophilus] lateralis). Physiol Biochem Zool 2022; 95:390-399. [DOI: 10.1086/721185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Hypothalamic remodeling of thyroid hormone signaling during hibernation in the arctic ground squirrel. Commun Biol 2022; 5:492. [PMID: 35606540 PMCID: PMC9126913 DOI: 10.1038/s42003-022-03431-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/29/2022] [Indexed: 12/16/2022] Open
Abstract
Hibernation involves prolonged intervals of profound metabolic suppression periodically interrupted by brief arousals to euthermy, the function of which is unknown. Annual cycles in mammals are timed by a photoperiodically-regulated thyroid-hormone-dependent mechanism in hypothalamic tanycytes, driven by thyrotropin (TSH) in the pars tuberalis (PT), which regulates local TH-converting deiodinases and triggers remodeling of neuroendocrine pathways. We demonstrate that over the course of hibernation in continuous darkness, arctic ground squirrels (Urocitellus parryii) up-regulate the retrograde TSH/Deiodinase/TH pathway, remodel hypothalamic tanycytes, and activate the reproductive axis. Forcing the premature termination of hibernation by warming animals induced hypothalamic deiodinase expression and the accumulation of secretory granules in PT thyrotrophs and pituitary gonadotrophs, but did not further activate the reproductive axis. We suggest that periodic arousals may allow for the transient activation of hypothalamic thyroid hormone signaling, cellular remodeling, and re-programming of brain circuits in preparation for the short Arctic summer. Arctic ground squirrels hibernating in darkness activate the pars tuberalis - hypothalamus thyroid hormone signaling pathway, remodel hypothalamic tanycytes, and activate the reproductive axis.
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10
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Verma V, Kumari R, Singaravel M. Chronic altered light-dark cycle differentially affects hippocampal CA1 and DG neuronal arborization in diurnal and nocturnal rodents. Chronobiol Int 2022; 39:665-677. [PMID: 34983277 DOI: 10.1080/07420528.2021.2023561] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The hippocampus, an extension of the temporal part of the cerebral cortex, plays a crucial role in learning and memory. Structural and functional complexity within the hippocampus is greatly affected by a variety of external environmental stimuli including alteration in the light-dark (LD) cycle. The effect of altered LD cycle in learning and memory associated cognitive impairment has been reported in rodents. However, a comparative study of underlying neuronal changes between nocturnal and diurnal species is not well explored. The objective of the present study was to explore the morphological changes in hippocampal CA1 and DG neurons in response to prolonged constant condition viz. constant light (LL) and constant darkness (DD) in diurnal squirrels and nocturnal mice. Animals (n = 5/group) were placed in chronocubicle under 12:12 h LD, LL and DD. After four weeks, brain tissues were collected and processed for Golgi-Cox staining to analyze morphological changes in CA1 and DG neurons. The total and basal dendritic length, basal dendrite number, branch end, the diameter of apical dendrite and spine density were analyzed. The results showed a significant reduction in structural complexity of CA1 and DG neurons of squirrels exposed to prolonged constant darkness, whereas mice showed a significant increase as compared to LD. However, a significantly reduced neuronal complexity was observed in both squirrels and mice exposed to prolonged constant light. The results obtained were further confirmed by Sholl analysis of CA1 and DG neurons. The present study suggests that prolonged constant light may cause adverse effects on the neuronal complexity of both diurnal and nocturnal animals, but constant darkness may cause adverse effects mainly to the diurnal animals.
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Affiliation(s)
- Vivek Verma
- Chronobiology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Ruchika Kumari
- Chronobiology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Muniyandi Singaravel
- Chronobiology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
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11
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Trujillo-Estrada L, Vanderklish PW, Nguyen MMT, Kuang RR, Nguyen C, Huynh E, da Cunha C, Javonillo DI, Forner S, Martini AC, Sarraf ST, Simmon VF, Baglietto-Vargas D, LaFerla FM. SPG302 Reverses Synaptic and Cognitive Deficits Without Altering Amyloid or Tau Pathology in a Transgenic Model of Alzheimer's Disease. Neurotherapeutics 2021; 18:2468-2483. [PMID: 34738197 PMCID: PMC8804111 DOI: 10.1007/s13311-021-01143-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 12/04/2022] Open
Abstract
Alzheimer's disease (AD) is conceptualized as a synaptic failure disorder in which loss of glutamatergic synapses is a major driver of cognitive decline. Thus, novel therapeutic strategies aimed at regenerating synapses may represent a promising approach to mitigate cognitive deficits in AD patients. At present, no disease-modifying drugs exist for AD, and approved therapies are palliative at best, lacking in the ability to reverse the synaptic failure. Here, we tested the efficacy of a novel synaptogenic small molecule, SPG302 - a 3rd-generation benzothiazole derivative that increases the density of axospinous glutamatergic synapses - in 3xTg-AD mice. Daily dosing of 3xTg-AD mice with SPG302 at 3 and 30 mg/kg (i.p.) for 4 weeks restored hippocampal synaptic density and improved cognitive function in hippocampal-dependent tasks. Mushroom and stubby spine profiles were increased by SPG302, and associated with enhanced expression of key postsynaptic proteins - including postsynaptic density protein 95 (PSD95), drebrin, and amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) - and increased colocalization of PSD95 with synaptophysin. Notably, SPG302 proved efficacious in this model without modifying Aβ and tau pathology. Thus, our study provides preclinical support for the idea that compounds capable of restoring synaptic density offer a viable strategy to reverse cognitive decline in AD.
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Affiliation(s)
- Laura Trujillo-Estrada
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
- Departamento Biología Celular, Genetica y Fisiologia, Instituto de Investigacion Biomedica de Malaga-IBIMA, Facultad de Ciencias, Universidad de Malaga, Malaga, Spain
- Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Peter W Vanderklish
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA.
| | - Marie Minh Thu Nguyen
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Run Rong Kuang
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Caroline Nguyen
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Eric Huynh
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Celia da Cunha
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Dominic Ibarra Javonillo
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Stefania Forner
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Alessandra C Martini
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Stella T Sarraf
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA
| | - Vincent F Simmon
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA.
| | - David Baglietto-Vargas
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
- Department of Neurobiology and Behavior, University of California, Irvine, CA, 92697-1450, USA.
- Departamento Biología Celular, Genetica y Fisiologia, Instituto de Investigacion Biomedica de Malaga-IBIMA, Facultad de Ciencias, Universidad de Malaga, Malaga, Spain.
- Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| | - Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
- Department of Neurobiology and Behavior, University of California, Irvine, CA, 92697-1450, USA.
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12
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Huang YG, Flaherty SJ, Pothecary CA, Foster RG, Peirson SN, Vyazovskiy VV. The relationship between fasting-induced torpor, sleep, and wakefulness in laboratory mice. Sleep 2021; 44:zsab093. [PMID: 33838033 PMCID: PMC8436144 DOI: 10.1093/sleep/zsab093] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 04/03/2021] [Indexed: 11/30/2022] Open
Abstract
STUDY OBJECTIVES Torpor is a regulated and reversible state of metabolic suppression used by many mammalian species to conserve energy. Whereas the relationship between torpor and sleep has been well-studied in seasonal hibernators, less is known about the effects of fasting-induced torpor on states of vigilance and brain activity in laboratory mice. METHODS Continuous monitoring of electroencephalogram (EEG), electromyogram (EMG), and surface body temperature was undertaken in adult, male C57BL/6 mice over consecutive days of scheduled restricted feeding. RESULTS All animals showed bouts of hypothermia that became progressively deeper and longer as fasting progressed. EEG and EMG were markedly affected by hypothermia, although the typical electrophysiological signatures of non-rapid eye movement (NREM) sleep, rapid eye movement (REM) sleep, and wakefulness enabled us to perform vigilance-state classification in all cases. Consistent with previous studies, hypothermic bouts were initiated from a state indistinguishable from NREM sleep, with EEG power decreasing gradually in parallel with decreasing surface body temperature. During deep hypothermia, REM sleep was largely abolished, and we observed shivering-associated intense bursts of muscle activity. CONCLUSIONS Our study highlights important similarities between EEG signatures of fasting-induced torpor in mice, daily torpor in Djungarian hamsters and hibernation in seasonally hibernating species. Future studies are necessary to clarify the effects on fasting-induced torpor on subsequent sleep.
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Affiliation(s)
- Yi-Ge Huang
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
| | - Sarah J Flaherty
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
| | - Carina A Pothecary
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE,UK
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT,UK
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13
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Rădulescu I, Drăgoi AM, Trifu SC, Cristea MB. Neuroplasticity and depression: Rewiring the brain's networks through pharmacological therapy (Review). Exp Ther Med 2021; 22:1131. [PMID: 34504581 PMCID: PMC8383338 DOI: 10.3892/etm.2021.10565] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/19/2021] [Indexed: 12/14/2022] Open
Abstract
In modern society, depression is one of the most common mental illness; however, its pathophysiology is not yet fully understood. A great body of evidence suggests that depression causes changes in neuroplasticity in specific regions of the brain which are correlated to symptom severity, negative emotional rumination as well as fear learning. Depression is correlated with atrophy of neurons in the cortical and limbic brain regions that control mood and emotion. Antidepressant therapy can exhibit effects on neuroplasticity and reverse the neuroanatomical changes found in depressed patients. The investigation of fast-acting agents that reverse behavioral and neuronal deficiencies of chronic depression, especially the glutamate receptor antagonist NMDA ketamine, and the cellular mechanisms underlying the rapid antidepressant actions of ketamine and related agents are of real interest in current research. Actual medication such as serotonin (5-HT) selective reuptake inhibitor (SSRI) antidepressants, require weeks to months of administration before a clear therapeutic response. The current review aimed to underline the negative effects of depression on neuroplasticity and present the current findings on the effects of antidepressant medication.
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Affiliation(s)
- Ioana Rădulescu
- Faculty of Psychology and Educational Sciences, University of Bucharest, 050663 Bucharest, Romania
| | - Ana Miruna Drăgoi
- Department of Psychiatry, 'Prof. Dr. Alex. Obregia' Clinical Hospital of Psychiatry, 041914 Bucharest, Romania
| | - Simona Corina Trifu
- Department of Clinical Neurosciences, 'Carol Davila' University of Medicine and Pharmacy, 020021 Bucharest, Romania
| | - Mihai Bogdan Cristea
- Department of Morphological Sciences, 'Carol Davila' University of Medicine and Pharmacy, 020021 Bucharest, Romania
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14
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Myrka A, Buck L. Cytoskeletal Arrest: An Anoxia Tolerance Mechanism. Metabolites 2021; 11:metabo11080561. [PMID: 34436502 PMCID: PMC8401981 DOI: 10.3390/metabo11080561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 12/16/2022] Open
Abstract
Polymerization of actin filaments and microtubules constitutes a ubiquitous demand for cellular adenosine-5′-triphosphate (ATP) and guanosine-5′-triphosphate (GTP). In anoxia-tolerant animals, ATP consumption is minimized during overwintering conditions, but little is known about the role of cell structure in anoxia tolerance. Studies of overwintering mammals have revealed that microtubule stability in neurites is reduced at low temperature, resulting in withdrawal of neurites and reduced abundance of excitatory synapses. Literature for turtles is consistent with a similar downregulation of peripheral cytoskeletal activity in brain and liver during anoxic overwintering. Downregulation of actin dynamics, as well as modification to microtubule organization, may play vital roles in facilitating anoxia tolerance. Mitochondrial calcium release occurs during anoxia in turtle neurons, and subsequent activation of calcium-binding proteins likely regulates cytoskeletal stability. Production of reactive oxygen species (ROS) formation can lead to catastrophic cytoskeletal damage during overwintering and ROS production can be regulated by the dynamics of mitochondrial interconnectivity. Therefore, suppression of ROS formation is likely an important aspect of cytoskeletal arrest. Furthermore, gasotransmitters can regulate ROS levels, as well as cytoskeletal contractility and rearrangement. In this review we will explore the energetic costs of cytoskeletal activity, the cellular mechanisms regulating it, and the potential for cytoskeletal arrest being an important mechanism permitting long-term anoxia survival in anoxia-tolerant species, such as the western painted turtle and goldfish.
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Affiliation(s)
- Alexander Myrka
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada;
| | - Leslie Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada;
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
- Correspondence: ; Tel.: +1-416-978-3506
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15
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Rusakov DA, Stewart MG. Synaptic environment and extrasynaptic glutamate signals: The quest continues. Neuropharmacology 2021; 195:108688. [PMID: 34174263 DOI: 10.1016/j.neuropharm.2021.108688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/11/2022]
Abstract
Behaviour of a mammal relies on the brain's excitatory circuits equipped with glutamatergic synapses. In most cases, glutamate escaping from the synaptic cleft is rapidly buffered and taken up by high-affinity transporters expressed by nearby perisynaptic astroglial processes (PAPs). The spatial relationship between glutamatergic synapses and PAPs thus plays a crucial role in understanding glutamate signalling actions, yet its intricate features can only be fully appreciated using methods that operate beyond the diffraction limit of light. Here, we examine principal aspects pertaining to the receptor actions of glutamate, inside and outside the synaptic cleft in the brain, where the organisation of synaptic micro-physiology and micro-environment play a critical part. In what conditions and how far glutamate can escape the synaptic cleft activating its target receptors outside the immediate synapse has long been the subject of debate. Evidence is also emerging that neuronal activity- and astroglia-dependent glutamate spillover actions could be important across the spectrum of cognitive functions This article is part of the special issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Michael G Stewart
- Dept of Life Sciences, The Open University, Milton Keynes, MK7 6AA, UK.
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16
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Gold AR, Glanzman DL. The central importance of nuclear mechanisms in the storage of memory. Biochem Biophys Res Commun 2021; 564:103-113. [PMID: 34020774 DOI: 10.1016/j.bbrc.2021.04.125] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022]
Abstract
The neurobiological nature of the memory trace (engram) remains controversial. The most widely accepted hypothesis at present is that long-term memory is stored as stable, learning-induced changes in synaptic connections. This hypothesis, the synaptic plasticity hypothesis of memory, is supported by extensive experimental data gathered from over 50 years of research. Nonetheless, there are important mnemonic phenomena that the synaptic plasticity hypothesis cannot, or cannot readily, account for. Furthermore, recent work indicates that epigenetic and genomic mechanisms play heretofore underappreciated roles in memory. Here, we critically assess the evidence that supports the synaptic plasticity hypothesis and discuss alternative non-synaptic, nuclear mechanisms of memory storage, including DNA methylation and retrotransposition. We argue that long-term encoding of memory is mediated by nuclear processes; synaptic plasticity, by contrast, represents a means of relatively temporary memory storage. In addition, we propose that memories are evaluated for their mnemonic significance during an initial period of synaptic storage; if assessed as sufficiently important, the memories then undergo nuclear encoding.
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Affiliation(s)
- Adam R Gold
- Behavioral Neuroscience Program, Department of Psychology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
| | - David L Glanzman
- Department of Integrative Biology & Physiology, UCLA College, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
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17
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Giroud S, Habold C, Nespolo RF, Mejías C, Terrien J, Logan SM, Henning RH, Storey KB. The Torpid State: Recent Advances in Metabolic Adaptations and Protective Mechanisms †. Front Physiol 2021; 11:623665. [PMID: 33551846 PMCID: PMC7854925 DOI: 10.3389/fphys.2020.623665] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 12/18/2022] Open
Abstract
Torpor and hibernation are powerful strategies enabling animals to survive periods of low resource availability. The state of torpor results from an active and drastic reduction of an individual's metabolic rate (MR) associated with a relatively pronounced decrease in body temperature. To date, several forms of torpor have been described in all three mammalian subclasses, i.e., monotremes, marsupials, and placentals, as well as in a few avian orders. This review highlights some of the characteristics, from the whole organism down to cellular and molecular aspects, associated with the torpor phenotype. The first part of this review focuses on the specific metabolic adaptations of torpor, as it is used by many species from temperate zones. This notably includes the endocrine changes involved in fat- and food-storing hibernating species, explaining biomedical implications of MR depression. We further compare adaptive mechanisms occurring in opportunistic vs. seasonal heterotherms, such as tropical and sub-tropical species. Such comparisons bring new insights into the metabolic origins of hibernation among tropical species, including resistance mechanisms to oxidative stress. The second section of this review emphasizes the mechanisms enabling heterotherms to protect their key organs against potential threats, such as reactive oxygen species, associated with the torpid state. We notably address the mechanisms of cellular rehabilitation and protection during torpor and hibernation, with an emphasis on the brain, a central organ requiring protection during torpor and recovery. Also, a special focus is given to the role of an ubiquitous and readily-diffusing molecule, hydrogen sulfide (H2S), in protecting against ischemia-reperfusion damage in various organs over the torpor-arousal cycle and during the torpid state. We conclude that (i) the flexibility of torpor use as an adaptive strategy enables different heterothermic species to substantially suppress their energy needs during periods of severely reduced food availability, (ii) the torpor phenotype implies marked metabolic adaptations from the whole organism down to cellular and molecular levels, and (iii) the torpid state is associated with highly efficient rehabilitation and protective mechanisms ensuring the continuity of proper bodily functions. Comparison of mechanisms in monotremes and marsupials is warranted for understanding the origin and evolution of mammalian torpor.
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Affiliation(s)
- Sylvain Giroud
- Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Caroline Habold
- University of Strasbourg, CNRS, IPHC, UMR 7178, Strasbourg, France
| | - Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, ANID – Millennium Science Initiative Program-iBio, Valdivia, Chile
- Center of Applied Ecology and Sustainability, Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Mejías
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, ANID – Millennium Science Initiative Program-iBio, Valdivia, Chile
- Center of Applied Ecology and Sustainability, Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jérémy Terrien
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), UMR 7179, CNRS, Muséum National d’Histoire Naturelle, Brunoy, France
| | | | - Robert H. Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, Netherlands
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18
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Duquette A, Pernègre C, Veilleux Carpentier A, Leclerc N. Similarities and Differences in the Pattern of Tau Hyperphosphorylation in Physiological and Pathological Conditions: Impacts on the Elaboration of Therapies to Prevent Tau Pathology. Front Neurol 2021; 11:607680. [PMID: 33488502 PMCID: PMC7817657 DOI: 10.3389/fneur.2020.607680] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022] Open
Abstract
Tau protein, a neuronal microtubule-associated protein, becomes hyperphosphorylated in several neurodegenerative diseases called tauopathies. Hyperphosphorylation of tau is correlated to its redistribution from the axon to the somato-dendritic compartment at early stages of tauopathies. Interestingly, tau hyperphosphorylation begins in different regions of the brain in each tauopathy. In some regions, both neurons and glial cells develop tau hyperphosphorylation. Tau hyperphosphorylation is also observed in physiological conditions such as hibernation and brain development. In the first section of present article, we will review the spatiotemporal and cellular distribution of hyperphosphorylated tau in the most frequent tauopathies. In the second section, we will compare the pattern of tau hyperphosphorylation in physiological and pathological conditions and discuss the sites that could play a pivotal role in the conversion of non-toxic to toxic forms of hyperphosphorylated tau. Furthermore, we will discuss the role of hyperphosphorylated tau in physiological and pathological conditions and the fact that tau hyperphosphorylation is reversible in physiological conditions but not in a pathological ones. In the third section, we will speculate how the differences and similarities between hyperphosphorylated tau in physiological and pathological conditions could impact the elaboration of therapies to prevent tau pathology. In the fourth section, the different therapeutic approaches using tau as a direct or indirect therapeutic target will be presented.
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Affiliation(s)
- Antoine Duquette
- Research Center of the University of Montreal Hospital (CRCHUM), Montréal, QC, Canada.,Département de Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Camille Pernègre
- Research Center of the University of Montreal Hospital (CRCHUM), Montréal, QC, Canada.,Département de Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Ariane Veilleux Carpentier
- Research Center of the University of Montreal Hospital (CRCHUM), Montréal, QC, Canada.,Département de Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Nicole Leclerc
- Research Center of the University of Montreal Hospital (CRCHUM), Montréal, QC, Canada.,Département de Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
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19
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Shi Z, Qin M, Huang L, Xu T, Chen Y, Hu Q, Peng S, Peng Z, Qu LN, Chen SG, Tuo QH, Liao DF, Wang XP, Wu RR, Yuan TF, Li YH, Liu XM. Human torpor: translating insights from nature into manned deep space expedition. Biol Rev Camb Philos Soc 2020; 96:642-672. [PMID: 33314677 DOI: 10.1111/brv.12671] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/09/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
During a long-duration manned spaceflight mission, such as flying to Mars and beyond, all crew members will spend a long period in an independent spacecraft with closed-loop bioregenerative life-support systems. Saving resources and reducing medical risks, particularly in mental heath, are key technology gaps hampering human expedition into deep space. In the 1960s, several scientists proposed that an induced state of suppressed metabolism in humans, which mimics 'hibernation', could be an ideal solution to cope with many issues during spaceflight. In recent years, with the introduction of specific methods, it is becoming more feasible to induce an artificial hibernation-like state (synthetic torpor) in non-hibernating species. Natural torpor is a fascinating, yet enigmatic, physiological process in which metabolic rate (MR), body core temperature (Tb ) and behavioural activity are reduced to save energy during harsh seasonal conditions. It employs a complex central neural network to orchestrate a homeostatic state of hypometabolism, hypothermia and hypoactivity in response to environmental challenges. The anatomical and functional connections within the central nervous system (CNS) lie at the heart of controlling synthetic torpor. Although progress has been made, the precise mechanisms underlying the active regulation of the torpor-arousal transition, and their profound influence on neural function and behaviour, which are critical concerns for safe and reversible human torpor, remain poorly understood. In this review, we place particular emphasis on elaborating the central nervous mechanism orchestrating the torpor-arousal transition in both non-flying hibernating mammals and non-hibernating species, and aim to provide translational insights into long-duration manned spaceflight. In addition, identifying difficulties and challenges ahead will underscore important concerns in engineering synthetic torpor in humans. We believe that synthetic torpor may not be the only option for manned long-duration spaceflight, but it is the most achievable solution in the foreseeable future. Translating the available knowledge from natural torpor research will not only benefit manned spaceflight, but also many clinical settings attempting to manipulate energy metabolism and neurobehavioural functions.
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Affiliation(s)
- Zhe Shi
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.,Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China
| | - Meng Qin
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Lu Huang
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, 510632, China
| | - Tao Xu
- Department of Anesthesiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Ying Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Qin Hu
- College of Life Sciences and Bio-Engineering, Beijing University of Technology, Beijing, 100024, China
| | - Sha Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Zhuang Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Li-Na Qu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Shan-Guang Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Qin-Hui Tuo
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Duan-Fang Liao
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Xiao-Ping Wang
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ren-Rong Wu
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ti-Fei Yuan
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226000, China
| | - Ying-Hui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Xin-Min Liu
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
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20
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Hadj-Moussa H, Wijenayake S, Storey KB. Multi-tissue profile of NFκB pathway regulation during mammalian hibernation. Comp Biochem Physiol B Biochem Mol Biol 2020; 246-247:110460. [PMID: 32445797 DOI: 10.1016/j.cbpb.2020.110460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/12/2020] [Accepted: 05/14/2020] [Indexed: 11/17/2022]
Abstract
Hibernators have evolved effective mechanisms to overcome the challenges of torpor-arousal cycling. This study focuses on the antioxidant and inflammatory defenses under the control of the redox-sensitive and inflammatory-centered NFκB transcription factor in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), a well-established model of mammalian hibernation. While hibernators significantly depress oxygen consumption and overall metabolic rate during torpor, arousal brings with it a rapid increase in respiration that is associated with an influx of reactive oxygen species. As such, hibernators employ a variety of antioxidant defenses to combat oxidative damage. Herein, we used Luminex multiplex technology to examine the expression of key proteins in the NFκB transcriptional network, including NFκB, super-repressor IκBα, upstream activators TNFR1 and FADD, and downstream target c-Myc. Transcription factor DNA-binding ELISAs were also used to measure the relative degree of NFκB binding to DNA during hibernation. Analyses were performed across eight different tissues, cerebral cortex, brainstem, white and brown adipose tissue, heart, liver, kidney, and spleen, during euthermic control and late torpor to highlight tissue-specific NFκB mediated cytoprotective responses against oxidative stress experienced during torpor-arousal. Our findings demonstrated brain-specific NFκB activation during torpor, with elevated levels of upstream activators, inactive-phosphorylated IκBα, active-phosphorylated NFκB, and enhanced NFκB-DNA binding. Protein levels of downstream protein, c-Myc, also increased in the brain and adipose tissues during late torpor. The results show that NFκB regulation might serve a critical neuroprotective and cytoprotective role in hibernating brains and selective peripheral tissue.
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Affiliation(s)
- Hanane Hadj-Moussa
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
| | - Sanoji Wijenayake
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada; Department of Biological Sciences and Center for Environmental Epigenetics and Development, University of Toronto, Toronto, ON, Canada
| | - Kenneth B Storey
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.
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21
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Regalado-Reyes M, Benavides-Piccione R, Fernaud-Espinosa I, DeFelipe J, León-Espinosa G. Effect of Phosphorylated Tau on Cortical Pyramidal Neuron Morphology during Hibernation. Cereb Cortex Commun 2020; 1:tgaa018. [PMID: 34296096 PMCID: PMC8152943 DOI: 10.1093/texcom/tgaa018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 05/02/2020] [Accepted: 05/03/2020] [Indexed: 12/17/2022] Open
Abstract
The dendritic spines of pyramidal cells are the main postsynaptic target of excitatory glutamatergic synapses. Morphological alterations have been described in hippocampal dendritic spines during hibernation-a state of inactivity and metabolic depression that occurs via a transient neuronal tau hyperphosphorylation. Here, we have used the hibernating Syrian hamster to investigate the effect of hyperphosphorylated tau regarding neocortical neuronal structure. In particular, we examined layer Va pyramidal neurons. Our results indicate that hibernation does not promote significant changes in dendritic spine density. However, tau hyperphosphorylated neurons show a decrease in complexity, an increase in the tortuosity of the apical dendrites, and an increase in the diameter of the basal dendrites. Tau protein hyperphosphorylation and aggregation have been associated with loss or alterations of dendritic spines in neurodegenerative diseases, such as Alzheimer's disease (AD). Our results may shed light on the correlation between tau hyperphosphorylation and the neuropathological processes in AD. Moreover, we observed changes in the length and area of the apical and basal dendritic spines during hibernation regardless of tau hyperphosphorylation. The morphological changes observed here also suggest region specificity, opening up debate about a possible relationship with the differential brain activity registered in these regions in previous studies.
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Affiliation(s)
- Mamen Regalado-Reyes
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28002, Spain
| | - Ruth Benavides-Piccione
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28002, Spain
| | - Isabel Fernaud-Espinosa
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28002, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28002, Spain
| | - Gonzalo León-Espinosa
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28002, Spain
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22
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León-Espinosa G, DeFelipe J, Muñoz A. The Golgi Apparatus of Neocortical Glial Cells During Hibernation in the Syrian Hamster. Front Neuroanat 2019; 13:92. [PMID: 31824270 PMCID: PMC6882278 DOI: 10.3389/fnana.2019.00092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 10/28/2019] [Indexed: 12/15/2022] Open
Abstract
Hibernating mammals undergo torpor periods characterized by a general decrease in body temperature, metabolic rate, and brain activity accompanied by complex adaptive brain changes that appear to protect the brain from extreme conditions of hypoxia and low temperatures. These processes are accompanied by morphological and neurochemical changes in the brain including those in cortical neurons such as the fragmentation and reduction of the Golgi apparatus (GA), which both reverse a few hours after arousal from the torpor state. In the present study, we characterized – by immunofluorescence and confocal microscopy – the GA of cortical astrocytes, oligodendrocytes, and microglial cells in the Syrian hamster, which is a facultative hibernator. We also show that after artificial induction of hibernation, in addition to neurons, the GA of glia in the Syrian hamster undergoes important structural changes, as well as modifications in the intensity of immunostaining and distribution patterns of Golgi structural proteins at different stages of the hibernation cycle.
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Affiliation(s)
- Gonzalo León-Espinosa
- Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain.,Departamento de Química y Bioquímica, Facultad de Farmacia, CEU San Pablo University, CEU Universities, Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain.,Instituto Cajal, CSIC, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain
| | - Alberto Muñoz
- Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain.,Instituto Cajal, CSIC, Madrid, Spain.,Departamento de Biología Celular, Universidad Complutense de Madrid, Madrid, Spain
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23
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Marchand A, Schwartz C. Perineuronal net expression in the brain of a hibernating mammal. Brain Struct Funct 2019; 225:45-56. [PMID: 31748912 DOI: 10.1007/s00429-019-01983-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 11/09/2019] [Indexed: 12/19/2022]
Abstract
During hibernation, mammals like the 13-lined ground squirrel cycle between physiological extremes. Most of the hibernation season is spent in bouts of torpor, where body temperature, heart rate, and cerebral blood flow are all very low. However, the ground squirrels periodically enter into interbout arousals (IBAs), where physiological parameters return to non-hibernating levels. During torpor, neurons in many brain regions shrink and become electrically quiescent, but reconnect and regain activity during IBA. Previous work showed evidence of extracellular matrix (ECM) changes occurring in the hypothalamus during hibernation that could be associated with this plasticity. Here, we examined expression of a specialized ECM structure, the perineuronal net (PNN), in the forebrain of ground squirrels in torpor, IBA, and summer (non-hibernating). PNNs are known to restrict plasticity, and could be important for retaining essential connections in the brain during hibernation. We found PNNs in three regions of the hypothalamus: ventrolateral hypothalamus, paraventricular nucleus (PVN), and anterior hypothalamic area. We also found PNNs throughout the cerebral cortex, amygdala, and lateral septum. The total area covered by PNNs within the PVN was significantly higher during IBA compared to non-hibernating and torpor (P < 0.01). Additionally, the amount of PNN coverage area per Nissl-stained neuron in the PVN was significantly higher in hibernation compared to non-hibernating (P < 0.05). No other significant differences were found across seasons. The PVN is involved in food intake and homeostasis, and PNNs found here could be essential for retaining vital life functions during hibernation.
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Affiliation(s)
- Anna Marchand
- Department of Biology, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA
| | - Christine Schwartz
- Department of Biology, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
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24
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Chazarin B, Ziemianin A, Evans AL, Meugnier E, Loizon E, Chery I, Arnemo JM, Swenson JE, Gauquelin-Koch G, Simon C, Blanc S, Lefai E, Bertile F. Limited Oxidative Stress Favors Resistance to Skeletal Muscle Atrophy in Hibernating Brown Bears ( Ursus Arctos). Antioxidants (Basel) 2019; 8:antiox8090334. [PMID: 31443506 PMCID: PMC6770786 DOI: 10.3390/antiox8090334] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/18/2019] [Accepted: 08/21/2019] [Indexed: 12/14/2022] Open
Abstract
Oxidative stress, which is believed to promote muscle atrophy, has been reported to occur in a few hibernators. However, hibernating bears exhibit efficient energy savings and muscle protein sparing, despite long-term physical inactivity and fasting. We hypothesized that the regulation of the oxidant/antioxidant balance and oxidative stress could favor skeletal muscle maintenance in hibernating brown bears. We showed that increased expressions of cold-inducible proteins CIRBP and RBM3 could favor muscle mass maintenance and alleviate oxidative stress during hibernation. Downregulation of the subunits of the mitochondrial electron transfer chain complexes I, II, and III, and antioxidant enzymes, possibly due to the reduced mitochondrial content, indicated a possible reduction of the production of reactive oxygen species in the hibernating muscle. Concomitantly, the upregulation of cytosolic antioxidant systems, under the control of the transcription factor NRF2, and the maintenance of the GSH/GSSG ratio suggested that bear skeletal muscle is not under a significant oxidative insult during hibernation. Accordingly, lower levels of oxidative damage were recorded in hibernating bear skeletal muscles. These results identify mechanisms by which limited oxidative stress may underlie the resistance to skeletal muscle atrophy in hibernating brown bears. They may constitute therapeutic targets for the treatment of human muscle atrophy.
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Affiliation(s)
- Blandine Chazarin
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-670000 Strasbourg, France
- Centre National d'Etudes Spatiales, CNES, F-75001 Paris, France
| | - Anna Ziemianin
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-670000 Strasbourg, France
- Centre National d'Etudes Spatiales, CNES, F-75001 Paris, France
| | - Alina L Evans
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Campus Evenstad, NO-2480 Koppang, Norway
| | - Emmanuelle Meugnier
- CarMen Laboratory, INSERM 1060, INRA 1397, University of Lyon, F-69600 Oullins, France
| | - Emmanuelle Loizon
- CarMen Laboratory, INSERM 1060, INRA 1397, University of Lyon, F-69600 Oullins, France
| | - Isabelle Chery
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-670000 Strasbourg, France
| | - Jon M Arnemo
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Campus Evenstad, NO-2480 Koppang, Norway
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Jon E Swenson
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
- Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
| | | | - Chantal Simon
- CarMen Laboratory, INSERM 1060, INRA 1397, University of Lyon, F-69600 Oullins, France
| | - Stéphane Blanc
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-670000 Strasbourg, France
| | - Etienne Lefai
- CarMen Laboratory, INSERM 1060, INRA 1397, University of Lyon, F-69600 Oullins, France
- Université d'Auvergne, INRA, UNH UMR1019, F-63122 Saint-Genès Champanelle, France
| | - Fabrice Bertile
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-670000 Strasbourg, France.
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25
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Szereszewski KE, Storey KB. Identification of a prosurvival neuroprotective mitochondrial peptide in a mammalian hibernator. Cell Biochem Funct 2019; 37:494-503. [PMID: 31387137 DOI: 10.1002/cbf.3422] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/10/2019] [Accepted: 06/05/2019] [Indexed: 02/03/2023]
Abstract
Hibernation requires the intricate regulation of physiological and biochemical adaptations to facilitate the decrease in metabolic rate and activation of prosurvival factors needed for winter survival. Mitochondria play important roles in eliciting these responses and in coordinating the required energy shifts. Herein, we report the presence of a novel mitochondrial peptide, s-humanin, in the hibernating 13-lined ground squirrel, Ictidomys tridecemlineatus. S-humanin was shown to have strong structural and sequence similarities to its human analogue, humanin-a powerful neuroprotective mitochondrial peptide. An assessment of the protein and gene expression levels of this peptide in ground squirrels revealed stark tissue-specific regulatory responses whereby transcript levels increased in brain cortex, skeletal muscle, and adipose tissues during hibernation, suggesting a protective torpor-induced activation. Accompanying peptide measurements found that s-humanin levels were suppressed in liver of torpid squirrels but enhanced in brain cortex. The enhanced transcript and protein levels of s-humanin in brain cortex suggest that it is actively involved in protecting delicate brain tissues and neuronal connections from hibernation-associated stresses. We propose that this squirrel-specific peptide is involved in modulating tissue-specific cytoprotective functions, expanding its role from human-specific neuroprotection to environmental stress protection. SIGNIFICANCE OF THE STUDY: Understanding the molecular mechanisms, which protect against oxidative stress in a model hibernator such as the ground squirrel, could be pivotal to the regulation of cytoprotection. This study expands on our knowledge of metabolic rate depression and could suggest a potential role for humanin therapy in neurodegenerative diseases.
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Affiliation(s)
- Kama E Szereszewski
- Institute of Biochemistry and Department of Biology, Ottawa, Ontario, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Ottawa, Ontario, Canada
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26
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Bullmann T, Feneberg E, Kretzschmann TP, Ogunlade V, Holzer M, Arendt T. Hibernation Impairs Odor Discrimination - Implications for Alzheimer's Disease. Front Neuroanat 2019; 13:69. [PMID: 31379517 PMCID: PMC6646461 DOI: 10.3389/fnana.2019.00069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 06/21/2019] [Indexed: 11/13/2022] Open
Abstract
Reversible formation of PHF-like phosphorylated tau, an early feature of Alzheimer's disease (AD) was previously shown to occur in torpor during hibernation in the Golden hamster (Syrian hamster, Mesocricetus auratus). Here, we tackled the question to what extent hibernating Golden hamsters can serve as a model for the early stage of AD. During early AD, anosmia, the loss of olfactory function, is a common and typical feature. We, thus, investigated tau phosphorylation, synaptic plasticity and behavioral physiology of the olfactory system during hibernation. Tau was phosphorylated on several AD-relevant epitopes, and distribution of PHF-like phosphorylated tau in the olfactory bulb was quite similar to what is seen in AD. Tau phosphorylation was not associated with a destabilization of microtubules and did not lead to fibril formation. Previously, we observed a transient spine reduction in pyramidal cells in the hippocampus, which is correlated with the distribution of phosphorylated tau. Here we show that granule cells in the olfactory bulb are devoid of phosphorylated tau and maintain their spines number during torpor. No reduction of synaptic proteins was observed. However, hibernation did impair the recall performance in a two-odor discrimination task. We conclude that hibernation is associated with a specific olfactory memory deficit, which might not be attributed to the formation of PHF-like phosphorylated tau within the olfactory bulb. We discuss a possible involvement of modulatory input provided by cholinergic neurons in the basal forebrain, which are affected by hibernation.
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Affiliation(s)
- Torsten Bullmann
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Emily Feneberg
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Tanja Petra Kretzschmann
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Vera Ogunlade
- Department of Neuropathology, University of Leipzig, Leipzig, Germany
| | - Max Holzer
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Thomas Arendt
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
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27
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Trivino-Paredes JS, Nahirney PC, Pinar C, Grandes P, Christie BR. Acute slice preparation for electrophysiology increases spine numbers equivalently in the male and female juvenile hippocampus: a DiI labeling study. J Neurophysiol 2019; 122:958-969. [PMID: 31268808 DOI: 10.1152/jn.00332.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hippocampal slices are widely used for in vitro electrophysiological experiments to study underlying mechanisms for synaptic transmission and plasticity, and there is a growing appreciation for sex differences in synaptic plasticity. To date, several studies have shown that the process of making slices from male animals can induce synaptogenesis in cornu ammonis area 1 (CA1) pyramidal cells, but there is a paucity of data for females and other brain regions. In the current study we use microcrystals of the lipophilic carbocyanine dye DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) to stain individual neurons in the CA1 and dentate gyrus (DG) hippocampal subfields of postnatal day 21 male and female rats. We show that the preparation of sections for electrophysiology produces significant increases in spines in sections obtained from females, similar to that observed in males. We also show that the procedures used for in vitro electrophysiology also result in significant spine increases in the DG and CA1 subfields. These results demonstrate the utility of this refined DiI procedure for staining neuronal dendrites and spines. They also show, for the first time, that in vitro electrophysiology slice preparations enhance spine numbers on hippocampal cells equivalently in both juvenile females and males.NEW & NOTEWORTHY This study introduces a new DiI technique that elucidates differences in spine numbers in juvenile female and male hippocampus, and shows that slice preparations for hippocampal electrophysiology in vitro may mask these differences.
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Affiliation(s)
- J S Trivino-Paredes
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - P C Nahirney
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.,Island Medical Program, University of British Columbia, Victoria, British Columbia, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - C Pinar
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - P Grandes
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.,Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Vizcaya, Spain.,Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - B R Christie
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.,Island Medical Program, University of British Columbia, Victoria, British Columbia, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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28
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Gattoni G, Bernocchi G. Calcium-Binding Proteins in the Nervous System during Hibernation: Neuroprotective Strategies in Hypometabolic Conditions? Int J Mol Sci 2019; 20:E2364. [PMID: 31086053 PMCID: PMC6540041 DOI: 10.3390/ijms20092364] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 05/06/2019] [Accepted: 05/11/2019] [Indexed: 02/07/2023] Open
Abstract
Calcium-binding proteins (CBPs) can influence and react to Ca2+ transients and modulate the activity of proteins involved in both maintaining homeostatic conditions and protecting cells in harsh environmental conditions. Hibernation is a strategy that evolved in vertebrate and invertebrate species to survive in cold environments; it relies on molecular, cellular, and behavioral adaptations guided by the neuroendocrine system that together ensure unmatched tolerance to hypothermia, hypometabolism, and hypoxia. Therefore, hibernation is a useful model to study molecular neuroprotective adaptations to extreme conditions, and can reveal useful applications to human pathological conditions. In this review, we describe the known changes in Ca2+-signaling and the detection and activity of CBPs in the nervous system of vertebrate and invertebrate models during hibernation, focusing on cytosolic Ca2+ buffers and calmodulin. Then, we discuss these findings in the context of the neuroprotective and neural plasticity mechanisms in the central nervous system: in particular, those associated with cytoskeletal proteins. Finally, we compare the expression of CBPs in the hibernating nervous system with two different conditions of neurodegeneration, i.e., platinum-induced neurotoxicity and Alzheimer's disease, to highlight the similarities and differences and demonstrate the potential of hibernation to shed light into part of the molecular mechanisms behind neurodegenerative diseases.
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Affiliation(s)
- Giacomo Gattoni
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
| | - Graziella Bernocchi
- Former Full Professor of Zoology, Neurogenesis and Comparative Neuromorphology, (Residence address) Viale Matteotti 73, I-27100 Pavia, Italy.
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29
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Horowitz JM, Horwitz BA. Extreme Neuroplasticity of Hippocampal CA1 Pyramidal Neurons in Hibernating Mammalian Species. Front Neuroanat 2019; 13:9. [PMID: 30814935 PMCID: PMC6381046 DOI: 10.3389/fnana.2019.00009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/21/2019] [Indexed: 11/13/2022] Open
Abstract
In awake and behaving mammals (with core and brain temperatures at ~37°C), hippocampal neurons have anatomical and physiological properties that support formation of memories. However, studies of hibernating mammalian species suggest that as hippocampal temperature falls to values below ~10°C, CA1 neurons lose their ability to generate long term potentiation (LTP), a basic form of neuroplasticity. That is, the persistent increase in CA3-CA1 synaptic strength following high-frequency stimulation of CA3 fibers (the hallmark of LTP generation at 37°C) is no longer observed at low brain temperatures although the neurons retain their ability to generate action potentials. In this review, we examine the relationship of LTP to recently observed CA1 structural changes in pyramidal neurons during the hibernation cycle, including the reversible formation of hyperphosphorylated tau. While CA1 neurons appear to be stripped of their ability to generate LTP at low temperatures, their ability to still generate action potentials is consistent with the longstanding proposal that they have projections to neural circuits controlling arousal state throughout the hibernation cycle. Recent anatomical studies significantly refine and extend previous studies of cellular plasticity and arousal state and suggest experiments that further delineate the mechanisms underlying the extreme plasticity of these CA1 neurons.
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Affiliation(s)
- John M Horowitz
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Barbara A Horwitz
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
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30
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Mandic M, Regan MD. Can variation among hypoxic environments explain why different fish species use different hypoxic survival strategies? ACTA ACUST UNITED AC 2018; 221:221/21/jeb161349. [PMID: 30381477 DOI: 10.1242/jeb.161349] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In aquatic environments, hypoxia is a multi-dimensional stressor that can vary in O2 level (partial pressure of O2 in water, PwO2 ), rate of induction and duration. Natural hypoxic environments can therefore be very different from one another. For the many fish species that have evolved to cope with these different hypoxic environments, survival requires adjusting energy supply and demand pathways to maintain energy balance. The literature describes innumerable ways that fishes combine aerobic metabolism, anaerobic metabolism and metabolic rate depression (MRD) to accomplish this, but it is unknown whether the evolutionary paths leading to these different strategies are determined primarily by species' phylogenetic histories, genetic constraint or their native hypoxic environments. We explored this idea by devising a four-quadrant matrix that bins different aquatic hypoxic environments according to their duration and PwO2 characteristics. We then systematically mined the literature for well-studied species native to environments within each quadrant, and, for each of 10 case studies, described the species' total hypoxic response (THR), defined as its hypoxia-induced combination of sustained aerobic metabolism, enhanced anaerobic metabolism and MRD, encompassing also the mechanisms underlying these metabolic modes. Our analysis revealed that fishes use a wide range of THRs, but that distantly related species from environments within the same matrix quadrant have converged on similar THRs. For example, environments of moderately hypoxic PwO2 favoured predominantly aerobic THRs, whereas environments of severely hypoxic PwO2 favoured MRD. Capacity for aerial emergence as well as predation pressure (aquatic and aerial) also contributed to these responses, in addition to other biotic and abiotic factors. Generally, it appears that the particular type of hypoxia experienced by a fish plays a major role in shaping its particular THR.
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Affiliation(s)
- Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Matthew D Regan
- Comparative Biosciences Department, University of Wisconsin-Madison, Madison, WI 35706, USA
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31
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León-Espinosa G, Antón-Fernández A, Tapia-González S, DeFelipe J, Muñoz A. Modifications of the axon initial segment during the hibernation of the Syrian hamster. Brain Struct Funct 2018; 223:4307-4321. [PMID: 30219944 DOI: 10.1007/s00429-018-1753-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 09/09/2018] [Indexed: 02/07/2023]
Abstract
Mammalian hibernation is a natural process in which the brain undergoes profound adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. In addition to a virtual cessation of neural and metabolic activity, these changes include a decrease in adult neurogenesis; the retraction of neuronal dendritic trees; changes in dendritic spines and synaptic connections; fragmentation of the Golgi apparatus; and the phosphorylation of the microtubule-associated protein tau. Furthermore, alterations of microglial cells also occur in torpor. Importantly, all of these changes are rapidly and fully reversed when the animals arouse from torpor state, with no apparent brain damage occurring. Thus, hibernating animals are excellent natural models to study different aspects of brain plasticity. The axon initial segment (AIS) is critical for the initiation of action potentials in neurons and is an efficient site for the regulation of neural activity. This specialized structure-characterized by the expression of different types of ion channels and adhesion, scaffolding and cytoskeleton proteins-is subjected to morpho-functional plastic changes upon variations in neural activity or in pathological conditions. Here, we used immunocytochemistry and 3D confocal microscopy reconstruction techniques to measure the possible morphological differences in the AIS of neocortical (layers II-III and V) and hippocampal (CA1) neurons during the hibernation of the Syrian hamster. Our results indicate that the general integrity of the AIS is resistant to the ischemia/hypoxia conditions that are characteristic of the torpor phase of hibernation. In addition, the length of the AIS significantly increased in all the regions studied-by about 16-20% in torpor animals compared to controls, suggesting the existence of compensatory mechanisms in response to a decrease in neuronal activity during the torpor phase of hibernation. Furthermore, in double-labeling experiment, we found that the AIS in layer V of torpid animals was longer in neurons expressing phospho-tau than in those not labeled for phospho-tau. This suggests that AIS plastic changes were more marked in phospho-tau accumulating neurons. Overall, the results further emphasize that mammalian hibernation is a good physiological model to study AIS plasticity mechanisms in non-pathological conditions.
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Affiliation(s)
- Gonzalo León-Espinosa
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,Facultad de Farmacia, Universidad San Pablo CEU, Madrid, Spain
| | - Alejandro Antón-Fernández
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Silvia Tapia-González
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Javier DeFelipe
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain
| | - Alberto Muñoz
- Instituto Cajal, CSIC, Madrid, Spain. .,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain. .,Departamento de Biología Celular, Universidad Complutense, Madrid, Spain.
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32
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Heldstab SA, Isler K, van Schaik CP. Hibernation constrains brain size evolution in mammals. J Evol Biol 2018; 31:1582-1588. [PMID: 30030877 DOI: 10.1111/jeb.13353] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 07/09/2018] [Accepted: 07/16/2018] [Indexed: 12/22/2022]
Abstract
The expensive brain hypothesis predicts that the lowest stable level of steady energy input acts as a strong constraint on a species' brain size, and thus, that periodic troughs in net energy intake should select for reduced brain size relative to body mass. Here, we test this prediction for the extreme case of hibernation. Hibernators drastically reduce food intake for up to several months and are therefore expected to have smaller relative brain sizes than nonhibernating species. Using a comparative phylogenetic approach on brain size estimates of 1104 mammalian species, and controlling for possible confounding variables, we indeed found that the presence of hibernation in mammals is correlated with decreased relative brain size. This result adds to recent comparative work across mammals and amphibians supporting the idea that environmental seasonality (where in extremis hibernation is necessary for survival) imposes an energetic challenge and thus acts as an evolutionary constraint on relative brain size.
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Affiliation(s)
- Sandra A Heldstab
- Department of Anthropology, University of Zurich, Zurich, Switzerland
| | - Karin Isler
- Department of Anthropology, University of Zurich, Zurich, Switzerland
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33
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Lázaro J, Hertel M, Sherwood CC, Muturi M, Dechmann DKN. Profound seasonal changes in brain size and architecture in the common shrew. Brain Struct Funct 2018; 223:2823-2840. [PMID: 29663134 PMCID: PMC5995987 DOI: 10.1007/s00429-018-1666-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/10/2018] [Indexed: 11/28/2022]
Abstract
The seasonal changes in brain size of some shrews represent the most drastic reversible transformation in the mammalian central nervous system known to date. Brain mass decreases 10-26% from summer to winter and regrows 9-16% in spring, but the underlying structural changes at the cellular level are not yet understood. Here, we describe the volumetric differences in brain structures between seasons and sexes of the common shrew (Sorex araneus) in detail, confirming that changes in different brain regions vary in the magnitude of change. Notably, shrews show a decrease in hypothalamus, thalamus, and hippocampal volume and later regrowth in spring, whereas neocortex and striatum volumes decrease in winter and do not recover in size. For some regions, males and females showed different patterns of seasonal change from each other. We also analyzed the underlying changes in neuron morphology. We observed a general decrease in soma size and total dendrite volume in the caudoputamen and anterior cingulate cortex. This neuronal retraction may partially explain the overall tissue shrinkage in winter. While not sufficient to explain the entire seasonal process, it represents a first step toward understanding the mechanisms beneath this remarkable phenomenon.
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Affiliation(s)
- Javier Lázaro
- Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, 78315, Radolfzell, Germany.
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| | - Moritz Hertel
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, 82319, Seewiesen, Germany
| | - Chet C Sherwood
- Department of Anthropology, The George Washington University, 20052, Washington, DC, USA
| | - Marion Muturi
- Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, 78315, Radolfzell, Germany
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Dina K N Dechmann
- Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, 78315, Radolfzell, Germany
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
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34
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Morphoregulatory functions of the RNA-binding motif protein 3 in cell spreading, polarity and migration. Sci Rep 2018; 8:7367. [PMID: 29743635 PMCID: PMC5943363 DOI: 10.1038/s41598-018-25668-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/27/2018] [Indexed: 02/01/2023] Open
Abstract
RNA-binding proteins are emerging as key regulators of transitions in cell morphology. The RNA-binding motif protein 3 (RBM3) is a cold-inducible RNA-binding protein with broadly relevant roles in cellular protection, and putative functions in cancer and development. Several findings suggest that RBM3 has morphoregulatory functions germane to its roles in these contexts. For example, RBM3 helps maintain the morphological integrity of cell protrusions during cell stress and disease. Moreover, it is highly expressed in migrating neurons of the developing brain and in cancer invadopodia, suggesting roles in migration. We here show that RBM3 regulates cell polarity, spreading and migration. RBM3 was present in spreading initiation centers, filopodia and blebs that formed during cell spreading in cell lines and primary myoblasts. Reducing RBM3 triggered exaggerated spreading, increased RhoA expression, and a loss of polarity that was rescued by Rho kinase inhibition and overexpression of CRMP2. High RBM3 expression enhanced the motility of cells migrating by a mesenchymal mode involving extension of long protrusions, whereas RBM3 knockdown slowed migration, greatly reducing the ability of cells to extend protrusions and impairing multiple processes that require directional migration. These data establish novel functions of RBM3 of potential significance to tissue repair, metastasis and development.
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35
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Changes in neocortical and hippocampal microglial cells during hibernation. Brain Struct Funct 2017; 223:1881-1895. [PMID: 29260372 DOI: 10.1007/s00429-017-1596-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/15/2017] [Indexed: 12/29/2022]
Abstract
Mammalian hibernation proceeds alongside a wide range of complex brain adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. Using immunofluorescence, confocal microscopy, quantitative analysis methods and intracellular injections, we have characterized microglia morphological changes that occur in the neocortex and hippocampus of the Syrian hamster during hibernation. In euthermic hamsters, microglial cells showed the typical ramified/resting morphology with multiple long, thin and highly-branched processes homogeneously immunostained for Iba-1. However, during torpor, microglial cell process numbers increase significantly accompanied by a shortening of the Iba-1 immunoreactive processes, which show a fragmented appearance. Adaptative changes of microglial cells during torpor coursed with no expression of microglial cell activation markers. We discuss the possibility that these morphological changes may contribute to neuronal damage prevention during hibernation.
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36
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Roda E, Bottone MG, Insolia V, Barni S, Bernocchi G. Changes in the cerebellar cytoarchitecture of hibernating hedgehog Erinaceus europaeus L. (Mammalia): an immunocytochemical approach. EUROPEAN ZOOLOGICAL JOURNAL 2017. [DOI: 10.1080/24750263.2017.1380722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- E. Roda
- Department of Biology and Biotechnology “L. Spallanzani”, Laboratory of Cell Biology and Neurobiology, University of Pavia, Pavia, Italy
- Laboratory of Clinical & Experimental Toxicology and Poison Control Centre and National Toxicology Information Centre, Toxicology Unit, ICS Maugeri Spa Benefit Corporation, IRCCS of Pavia, Pavia, Italy
| | - M. G. Bottone
- Department of Biology and Biotechnology “L. Spallanzani”, Laboratory of Cell Biology and Neurobiology, University of Pavia, Pavia, Italy
| | - V. Insolia
- Department of Biology and Biotechnology “L. Spallanzani”, Laboratory of Cell Biology and Neurobiology, University of Pavia, Pavia, Italy
| | - S. Barni
- Department of Biology and Biotechnology “L. Spallanzani”, Laboratory of Cell Biology and Neurobiology, University of Pavia, Pavia, Italy
| | - G. Bernocchi
- Department of Biology and Biotechnology “L. Spallanzani”, Laboratory of Cell Biology and Neurobiology, University of Pavia, Pavia, Italy
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Birkel L. Decreased use of spatial pattern separation in contemporary lifestyles may contribute to hippocampal atrophy and diminish mental health. Med Hypotheses 2017; 107:55-63. [DOI: 10.1016/j.mehy.2017.07.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/14/2017] [Indexed: 10/19/2022]
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38
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Acute or Chronic? A Stressful Question. Trends Neurosci 2017; 40:525-535. [DOI: 10.1016/j.tins.2017.07.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/30/2017] [Accepted: 07/10/2017] [Indexed: 12/28/2022]
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39
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Yin Q, Zhang Y, Dong D, Lei M, Zhang S, Liao CC, Pan YH. Maintenance of neural activities in torpid Rhinolophus ferrumequinum bats revealed by 2D gel-based proteome analysis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1004-1019. [DOI: 10.1016/j.bbapap.2017.04.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/27/2017] [Accepted: 04/29/2017] [Indexed: 12/21/2022]
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40
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Luan Y, Ou J, Kunze VP, Qiao F, Wang Y, Wei L, Li W, Xie Z. Integrated transcriptomic and metabolomic analysis reveals adaptive changes of hibernating retinas. J Cell Physiol 2017; 233:1434-1445. [PMID: 28542832 DOI: 10.1002/jcp.26030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/24/2017] [Indexed: 12/24/2022]
Abstract
Hibernation is a seasonally adaptive strategy that allows hibernators to live through extremely cold conditions. Despite the profound reduction of blood flow to the retinas, hibernation causes no lasting retinal injury. Instead, hibernators show an increased tolerance to ischemic insults during the hibernation period. To understand the molecular changes of the retinas in response to hibernation, we applied an integrative transcriptome and metabolome analysis to explore changes in gene expression and metabolites of 13-lined ground squirrel retinas during hibernation. Metabolomic analysis showed a global decrease of ATP synthesis in hibernating retinas. Decreased glucose and galactose, increased beta-oxidation of carnitine and decreased storage of some amino acids in hibernating retinas indicated a shift of fuel use from carbohydrates to lipids and alternative usage of amino acids. Transcriptomic analysis revealed that the down-regulated genes were enriched in DNA-templated transcription and immune-related functions, while the up-regulated genes were enriched in mitochondrial inner membrane and DNA packaging-related functions. We further showed that a subset of genes underwent active alternative splicing events in response to hibernation. Finally, integrative analysis of the transcriptome and metabolome confirmed the shift of fuel use in the hibernating retina by the regulation of catabolism of amino acids and lipids. Through transcriptomic and metabolomic data, our analysis revealed the altered state of mitochondrial oxidative phosphorylation and the shift of energy source in the hibernating retina, advancing our understanding of the molecular mechanisms employed by hibernators. The data will also serve as a useful resource for the ocular and hibernation research communities.
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Affiliation(s)
- Yizhao Luan
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jingxing Ou
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Vincent P Kunze
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Fengyu Qiao
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Yan Wang
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lai Wei
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wei Li
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Zhi Xie
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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41
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Czenze ZJ, Jonasson KA, Willis CKR. Thrifty Females, Frisky Males: Winter Energetics of Hibernating Bats from a Cold Climate. Physiol Biochem Zool 2017. [DOI: 10.1086/692623] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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42
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Different patterns of changes between actin dynamics and synaptic density in the rat's primary visual cortex during a special period of visual development. Brain Res Bull 2017; 132:199-203. [PMID: 28602762 DOI: 10.1016/j.brainresbull.2017.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 05/04/2017] [Accepted: 06/05/2017] [Indexed: 01/05/2023]
Abstract
In our previous study, we found that the normalized levels of the synaptosomal filament actin (F-actin) to monomeric global actin (G-actin) ratio in the primary visual cortex (V1) of rats was significantly lower on postnatal day (P) 45 compared with P30, however, the synaptic density in the monocular area of primary visual cortex (V1M) maintained a stable high level from P30 to P45. The mechanisms underlying the different patterned of change in synaptic density and actin rearrangements from P30 to P45 are unclear. During visual development, there is a synaptic pruning process in the binocular segment of primates' visual cortex (V1B) and we suppose the pruning activity may contribute to the decreased synaptosomal F-actin to G-actin ratio. To address this issue, first, samples were derived from the region of V1B for TEM analysis but no significant difference was demonstrated between the P30 and P45 groups. In addition, the expression of PSD-95 detected by immunobloting in the synaptosomes of V1 at P30 and P45 also showed no significant difference. Combined with the previous results of actin dynamics in the V1 and synaptic density in the V1M, we conclude that the synaptic density and actin dynamics in the rats' primary visual cortex are inter-related but not absolutely identical. This study suggests actin cytoskeleton not only provides the structural basis but also regulates a various array of cellular activities underlying synaptic function. Besides, it highlights a further research of synaptic pruning.
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Vyazovskiy VV, Palchykova S, Achermann P, Tobler I, Deboer T. Different Effects of Sleep Deprivation and Torpor on EEG Slow-Wave Characteristics in Djungarian Hamsters. Cereb Cortex 2017; 27:950-961. [PMID: 28168294 PMCID: PMC5390404 DOI: 10.1093/cercor/bhx020] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 12/21/2022] Open
Abstract
It has been shown previously in Djungarian hamsters that the initial electroencephalography (EEG) slow-wave activity (power in the 0.5–4.0 Hz band; SWA) in non-rapid eye movement (NREM) sleep following an episode of daily torpor is consistently enhanced, similar to the SWA increase after sleep deprivation (SD). However, it is unknown whether the network mechanisms underlying the SWA increase after torpor and SD are similar. EEG slow waves recorded in the neocortex during sleep reflect synchronized transitions between periods of activity and silence among large neuronal populations. We therefore set out to investigate characteristics of individual cortical EEG slow waves recorded during NREM sleep after 4 h SD and during sleep after emergence from an episode of daily torpor in adult male Djungarian hamsters. We found that during the first hour after both SD and torpor, the SWA increase was associated with an increase in slow-wave incidence and amplitude. However, the slopes of single slow waves during NREM sleep were steeper in the first hour after SD but not after torpor, and, in contrast to sleep after SD, the magnitude of change in slopes after torpor was unrelated to the changes in SWA. Furthermore, slow-wave slopes decreased progressively within the first 2 h after SD, while a progressive increase in slow-wave slopes was apparent during the first 2 h after torpor. The data suggest that prolonged waking and torpor have different effects on cortical network activity underlying slow-wave characteristics, while resulting in a similar homeostatic sleep response of SWA. We suggest that sleep plays an important role in network homeostasis after both waking and torpor, consistent with a recovery function for both states.
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Affiliation(s)
- V V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT Oxford, UK
| | | | - P Achermann
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - I Tobler
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - T Deboer
- Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, LUMC S-05-P, PO Box 9600, 2300 RC Leiden, the Netherlands
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44
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Mamelak M. Energy and the Alzheimer brain. Neurosci Biobehav Rev 2017; 75:297-313. [PMID: 28193453 DOI: 10.1016/j.neubiorev.2017.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/30/2017] [Accepted: 02/01/2017] [Indexed: 01/01/2023]
Abstract
The high energy demands of the poorly myelinated long axon hippocampal and cortical neurons render these neurons selectively vulnerable to degeneration in Alzheimer's disease. However, pathology engages all of the major elements of the neurovascular unit of the mature Alzheimer brain, the neurons, glia and blood vessels. Neurons present with retrograde degeneration of the axodendritic tree, capillaries with string vessels and markedly reduced densities and glia with signs of inflammatory activation. The neurons, capillaries and astrocytes of the mature Alzheimer brain harbor structurally defective mitochondria. Clinically, reduced glucose utilization, decades before cognitive deterioration, betrays ongoing energy insufficiency. β-hydroxybutyrate and γ-hydroxybutyrate can both provide energy to the brain when glucose utilization is blocked. Early work in mouse models of Alzheimer's disease demonstrate their ability to reverse the pathological changes in the Alzheimer brain and initial clinical trials reveal their ability to improve cognition and every day function. Supplying the brain with energy holds great promise for delaying the onset of Alzheimer's disease and slowing its progress.
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45
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Ballinger MA, Schwartz C, Andrews MT. Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation. Am J Physiol Regul Integr Comp Physiol 2017; 312:R301-R310. [PMID: 28077389 DOI: 10.1152/ajpregu.00314.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 01/06/2017] [Accepted: 01/08/2017] [Indexed: 11/22/2022]
Abstract
During hibernation, thirteen-lined ground squirrels (Ictidomys tridecemlineatus) regularly cycle between bouts of torpor and interbout arousal (IBA). Most of the brain is electrically quiescent during torpor but regains activity quickly upon arousal to IBA, resulting in extreme oscillations in energy demand during hibernation. We predicted increased functional capacity of brain mitochondria during hibernation compared with spring to accommodate the variable energy demands of hibernation. To address this hypothesis, we examined mitochondrial bioenergetics in the ground squirrel brain across three time points: spring (SP), torpor (TOR), and IBA. Respiration rates of isolated brain mitochondria through complex I of the electron transport chain were more than twofold higher in TOR and IBA than in SP (P < 0.05). We also found a 10% increase in membrane potential between hibernation and spring (P < 0.05), and that proton leak was lower in TOR and IBA than in SP. Finally, there was a 30% increase in calcium loading in SP brain mitochondria compared with TOR and IBA (P < 0.01). To analyze brain mitochondrial abundance between spring and hibernation, we measured the ratio of copy number in a mitochondrial gene (ND1) vs. a nuclear gene (B2M) in frozen cerebral cortex samples. No significant differences were observed in DNA copies between SP and IBA. These data show that brain mitochondrial bioenergetics are not static across the year and suggest that brain mitochondria function more effectively during the hibernation season, allowing for rapid production of energy to meet demand when extreme physiological changes are occurring.
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Affiliation(s)
- Mallory A Ballinger
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Christine Schwartz
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and.,Department of Biology, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
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Conrad CD, Ortiz JB, Judd JM. Chronic stress and hippocampal dendritic complexity: Methodological and functional considerations. Physiol Behav 2016; 178:66-81. [PMID: 27887995 DOI: 10.1016/j.physbeh.2016.11.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/16/2016] [Accepted: 11/18/2016] [Indexed: 12/30/2022]
Abstract
The current understanding of how chronic stress impacts hippocampal dendritic arbor complexity and the subsequent relationship to hippocampal-dependent spatial memory is reviewed. A surge in reports investigating hippocampal dendritic morphology is occurring, but with wide variations in methodological detail being reported. Consequently, this review systematically outlines the basic neuroanatomy of relevant hippocampal features to help clarify how chronic stress or glucocorticoids impact hippocampal dendritic complexity and how these changes occur in parallel with spatial cognition. Chronic stress often leads to hippocampal CA3 apical dendritic retraction first with other hippocampal regions (CA3 basal dendrites, CA1, dentate gyrus, DG) showing dendritic retraction when chronic stress is sufficiently robust or long lasting. The stress-induced reduction in hippocampal CA3 apical dendritic arbor complexity often coincides with impaired hippocampal function, such as spatial learning and memory. Yet, when chronic stress ends and a post-stress recovery period ensues, the atrophied dendritic arbors and poor spatial abilities often improve. However, this process differs from a simple reversal of chronic stress-induced deficits. Recent reports suggest that this return to baseline-like functioning is uniquely different from non-stressed controls, emphasizing the need for further studies to enhance our understanding of how a history of stress subsequently alters an organism's spatial abilities. To provide a consistent framework for future studies, this review concludes with an outline for a quick and easy reference on points to consider when planning chronic stress studies with the goal of measuring hippocampal dendritic complexity and spatial ability.
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Affiliation(s)
- Cheryl D Conrad
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States.
| | - J Bryce Ortiz
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States
| | - Jessica M Judd
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States
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León-Espinosa G, García E, Gómez-Pinedo U, Hernández F, DeFelipe J, Ávila J. Decreased adult neurogenesis in hibernating Syrian hamster. Neuroscience 2016; 333:181-92. [DOI: 10.1016/j.neuroscience.2016.07.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 07/08/2016] [Accepted: 07/11/2016] [Indexed: 12/29/2022]
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48
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Onufriev MV, Semenova TP, Volkova EP, Sergun’kina MA, Yakovlev AA, Zakharova NM, Gulyaeva NV. Seasonal changes in actin and Cdk5 expression in different brain regions of the Yakut ground squirrel (Spermophilus undulatus). NEUROCHEM J+ 2016. [DOI: 10.1134/s1819712416020070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Regan MD, Gill I, Richards JG. Calorespirometry reveals that goldfish prioritize aerobic metabolism over metabolic rate depression in all but near-anoxic environments. J Exp Biol 2016; 220:564-572. [DOI: 10.1242/jeb.145169] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/21/2016] [Indexed: 10/20/2022]
Abstract
Metabolic rate depression (MRD) has long been proposed as the key metabolic strategy of hypoxic survival, but surprisingly the effects of changes in hypoxic O2 tensions (PwO2) on MRD are largely unexplored. We simultaneously measured the O2 consumption rate (ṀO2) and metabolic heat of goldfish using calorespirometry to test the hypothesis that MRD is employed at hypoxic PwO2s and initiated just below Pcrit, the PwO2 below which ṀO2 is forced to progressively decline as the fish oxyconforms to decreasing PwO2. Specifically, we used closed-chamber and flow-through calorespirometry together with terminal sampling experiments to examine the effects of PwO2 and time on ṀO2, metabolic heat and anaerobic metabolism (lactate and ethanol production). The closed-chamber and flow-through experiments yielded slightly different results. Under closed-chamber conditions with a continually decreasing PwO2, goldfish showed a Pcrit of 3.0±0.3 kPa and metabolic heat production was only depressed at PwO2 between 0 and 0.67 kPa. Under flow-through conditions with PwO2 held at a variety of oxygen tensions for 1 and 4 h, goldfish also initiated MRD between 0 and 0.67 kPa but maintained ṀO2 to 0.67 kPa, indicating that Pcrit is at or below this PwO2. Anaerobic metabolism was strongly activated at PwO2 ≤1.3 kPa, but only used within the first hour at 1.3 and 0.67 kPa as anaerobic end-products did not accumulate between 1 and 4 h exposure. Taken together, it appears that goldfish reserve MRD for near-anoxia, supporting routine metabolic rate at sub-Pcrit PwO2s with the help of anaerobic glycolysis in the closed-chamber experiments, and aerobically after an initial (<1 h) activation of anaerobic metabolism in the flow-through experiments, even at 0.67 kPa PwO2.
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Affiliation(s)
- Matthew D. Regan
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Ivan Gill
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Jeffrey G. Richards
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
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Antón-Fernández A, León-Espinosa G, DeFelipe J, Muñoz A. Changes in the Golgi Apparatus of Neocortical and Hippocampal Neurons in the Hibernating Hamster. Front Neuroanat 2015; 9:157. [PMID: 26696838 PMCID: PMC4678224 DOI: 10.3389/fnana.2015.00157] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/16/2015] [Indexed: 01/01/2023] Open
Abstract
Hibernating animals have been used as models to study several aspects of the plastic changes that occur in the metabolism and physiology of neurons. These models are also of interest in the study of Alzheimer's disease because the microtubule-associated protein tau is hyperphosphorylated during the hibernation state known as torpor, similar to the pretangle stage of Alzheimer's disease. Hibernating animals undergo torpor periods with drops in body temperature and metabolic rate, and a virtual cessation of neural activity. These processes are accompanied by morphological and neurochemical changes in neurons, which reverse a few hours after coming out of the torpor state. Since tau has been implicated in the structural regulation of the neuronal Golgi apparatus (GA) we have used Western Blot and immunocytochemistry to analyze whether the GA is modified in cortical neurons of the Syrian hamster at different hibernation stages. The results show that, during the hibernation cycle, the GA undergo important structural changes along with differential modifications in expression levels and distribution patterns of Golgi structural proteins. These changes were accompanied by significant transitory reductions in the volume and surface area of the GA elements during torpor and arousal stages as compared with euthermic animals.
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Affiliation(s)
- Alejandro Antón-Fernández
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, CSICMadrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadrid, Spain
| | - Gonzalo León-Espinosa
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, CSICMadrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadrid, Spain
- Facultad de Farmacia, Universidad San Pablo CEUMadrid, Spain
| | - Javier DeFelipe
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, CSICMadrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades NeurodegenerativasMadrid, Spain
| | - Alberto Muñoz
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, CSICMadrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadrid, Spain
- Departamento de Biología Celular, Facultad de Biología, Universidad ComplutenseMadrid, Spain
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