151
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Gerkau NJ, Rakers C, Petzold GC, Rose CR. Differential effects of energy deprivation on intracellular sodium homeostasis in neurons and astrocytes. J Neurosci Res 2017; 95:2275-2285. [PMID: 28150887 DOI: 10.1002/jnr.23995] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/10/2016] [Accepted: 11/10/2016] [Indexed: 12/11/2022]
Abstract
The maintenance of a low intracellular sodium concentration by the Na+ /K+ -ATPase (NKA) is critical for brain function. In both neurons and glial cells, NKA activity is required to counteract changes in the sodium gradient due to opening of voltage- and ligand-gated channels and/or activation of sodium-dependent secondary active transporters. Because NKA consumes about 50% of cellular ATP, sodium homeostasis is strictly dependent on an intact cellular energy metabolism. Despite the high energetic costs of electrical signaling, neurons do not contain significant energy stores themselves, but rely on a close metabolic interaction with surrounding astrocytes. A disruption of energy supply as observed during focal ischemia causes a rapid drop in ATP in both neurons and astrocytes. There is accumulating evidence that dysregulation of intracellular sodium is an inherent consequence of a reduction in cellular ATP, triggering secondary failure of extra- and intracellular homeostasis of other ions -in particular potassium, calcium, and protons- and thereby promoting excitotoxicity. The characteristics, cellular mechanisms and direct consequences of harmful sodium influx, however, differ between neurons and astrocytes. Moreover, recent work has shown that an intact astrocyte metabolism and sodium homeostasis are critical to maintain the sodium homeostasis of surrounding neurons as well as their capacity to recover from imposed sodium influx. Understanding the mechanisms of sodium increases upon metabolic failure and the differential responses of neurons and glial cells as well as their metabolic interactions will be critical to fully unravel the events causing cellular malfunction, failure and cell death following energy depletion. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Niklas J Gerkau
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
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152
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Zhou J, Burns MP, Huynh L, Villapol S, Taub DD, Saavedra JM, Blackman MR. Temporal Changes in Cortical and Hippocampal Expression of Genes Important for Brain Glucose Metabolism Following Controlled Cortical Impact Injury in Mice. Front Endocrinol (Lausanne) 2017; 8:231. [PMID: 28955302 PMCID: PMC5601958 DOI: 10.3389/fendo.2017.00231] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury (TBI) causes transient increases and subsequent decreases in brain glucose utilization. The underlying molecular pathways are orchestrated processes and poorly understood. In the current study, we determined temporal changes in cortical and hippocampal expression of genes important for brain glucose/lactate metabolism and the effect of a known neuroprotective drug telmisartan on the expression of these genes after experimental TBI. Adult male C57BL/6J mice (n = 6/group) underwent sham or unilateral controlled cortical impact (CCI) injury. Their ipsilateral and contralateral cortex and hippocampus were collected 6 h, 1, 3, 7, 14, 21, and 28 days after injury. Expressions of several genes important for brain glucose utilization were determined by qRT-PCR. In results, (1) mRNA levels of three key enzymes in glucose metabolism [hexo kinase (HK) 1, pyruvate kinase, and pyruvate dehydrogenase (PDH)] were all increased 6 h after injury in the contralateral cortex, followed by decreases at subsequent times in the ipsilateral cortex and hippocampus; (2) capillary glucose transporter Glut-1 mRNA increased, while neuronal glucose transporter Glut-3 mRNA decreased, at various times in the ipsilateral cortex and hippocampus; (3) astrocyte lactate transporter MCT-1 mRNA increased, whereas neuronal lactate transporter MCT-2 mRNA decreased in the ipsilateral cortex and hippocampus; (4) HK2 (an isoform of hexokinase) expression increased at all time points in the ipsilateral cortex and hippocampus. GPR81 (lactate receptor) mRNA increased at various time points in the ipsilateral cortex and hippocampus. These temporal alterations in gene expression corresponded closely to the patterns of impaired brain glucose utilization reported in both TBI patients and experimental TBI rodents. The observed changes in hippocampal gene expression were delayed and prolonged, when compared with those in the cortex. The patterns of alterations were specific to different brain regions and exhibited different recovery periods following TBI. Oral administration of telmisartan (1 mg/kg, for 7 days, n = 10 per group) ameliorated cortical or hippocampal mRNA for Glut-1/3, MCT-1/2 and PDH in CCI mice. These data provide molecular evidence for dynamic alteration of multiple critical factors in brain glucose metabolism post-TBI and can inform further research for treating brain metabolic disorders post-TBI.
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Affiliation(s)
- June Zhou
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine, Washington, DC, United States
- *Correspondence: June Zhou,
| | - Mark P. Burns
- Department of Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
| | - Linda Huynh
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
| | - Sonia Villapol
- Department of Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
| | - Daniel D. Taub
- Translational Medicine Section, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular and Cell Biology, Georgetown University School of Medicine, Washington, DC, United States
| | - Juan M. Saavedra
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC, United States
| | - Marc R. Blackman
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine, Washington, DC, United States
- Department of Medicine George Washington University School of Medicine, Washington, DC, United States
- Department of Medicine, Georgetown University School of Medicine, Washington, DC, United States
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153
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Schättin A, de Bruin ED. Combining Exergame Training with Omega-3 Fatty Acid Supplementation: Protocol for a Randomized Controlled Study Assessing the Effect on Neuronal Structure/Function in the Elderly Brain. Front Aging Neurosci 2016; 8:283. [PMID: 27965570 PMCID: PMC5126064 DOI: 10.3389/fnagi.2016.00283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/11/2016] [Indexed: 11/13/2022] Open
Abstract
A common problem in the older population is the risk of falling and related injury, immobility, and reduced survival. Age-related neuronal changes, e.g., decline in gray-and white-matter, affect neuronal, cognitive, and motor functioning. The improvement of these factors might decrease fall events in elderly. Studies showed that administration of video game-based physical exercise, a so-called exergame, or omega-3 fatty acid (FA) may improve motor and/or cognitive functioning through neuronal changes in the brain of older adults. The aim of this study is to assess the effects of a combination of exergame training with omega-3 FA supplementation on the elderly brain. We hypothesize that an intervention using a combination approach differently affects on the neuronal structure and function of the elderly's brain as compared to the sole administration of exergame training. The study is a parallel, double-blinded, randomized controlled trial lasting 26 weeks. Sixty autonomous living, non-smoking, and right-handed healthy older (>65 years) adults who live independently or in a senior residency are included, randomized, and allocated to one of two study groups. The experimental group receives a daily amount of 13.5 ml fish oil (including 2.9 g of omega-3 FA), whereas the control group receives a daily amount of 13.5 ml olive oil for 26 weeks. After 16 weeks, both groups start with an exergame training program three times per week. Measurements are performed on three time-points by treatment blinded investigators: pre-intervention measurements, blood sample after 16 week, and post-intervention measurements. The main outcomes are motor evoked potentials of the right M. tibialis anterior (transcranial magnetic stimulation) and response-related potentials (electroencephalography) during a cognitive test. For secondary outcomes, reaction time during cognitive tests and spatio-temporal parameters during gait performance are measured. Statistics will include effect sizes and a 2 × 2-ANOVA with normally distributed data or the non-parametric equivalent for data not fulfilling normal distribution. The randomized controlled study is the first to investigate the effectiveness of exergame training combined with omega-3 FA in counteracting age- and behavioral-dependent neuronal changes in the brain. This study has been registered in the Swiss National Clinical Trials (SNCTP000001623) and the ISRCTN (ISRCTN12084831) Portals.
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Affiliation(s)
- Alexandra Schättin
- Department of Health Sciences and Technology, Institute of Human Movement Sciences and Sport, ETH Zurich Zurich, Switzerland
| | - Eling D de Bruin
- Department of Health Sciences and Technology, Institute of Human Movement Sciences and Sport, ETH Zurich Zurich, Switzerland
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154
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Xu H, Zhang H, Zhang J, Huang Q, Shen Z, Wu R. Evaluation of neuron-glia integrity by in vivo proton magnetic resonance spectroscopy: Implications for psychiatric disorders. Neurosci Biobehav Rev 2016; 71:563-577. [PMID: 27702600 DOI: 10.1016/j.neubiorev.2016.09.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 09/18/2016] [Accepted: 09/26/2016] [Indexed: 02/05/2023]
Abstract
Proton magnetic resonance spectroscopy (1H-MRS) has been widely applied in human studies. There is now a large literature describing findings of brain MRS studies with mental disorder patients including schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorders. However, the findings are mixed and cannot be reconciled by any of the existing interpretations. Here we proposed the new theory of neuron-glia integrity to explain the findings of brain 1H-MRS stuies. It proposed the neurochemical correlates of neuron-astrocyte integrity and axon-myelin integrity on the basis of update of neurobiological knowledge about neuron-glia communication and of experimental MRS evidence for impairments in neuron-glia integrity from the authors and the other investigators. Following the neuron-glia integrity theories, this review collected evidence showing that glutamate/glutamine change is a good marker for impaired neuron-astrocyte integrity and that changes in N-acetylaspartate and lipid precursors reflect impaired myelination. Moreover, this new theory enables us to explain the differences between MRS findings in neuropsychiatric and neurodegenerative disorders.
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Affiliation(s)
- Haiyun Xu
- The Mental Health Center, Shantou University Medical College, China.
| | - Handi Zhang
- The Mental Health Center, Shantou University Medical College, China
| | - Jie Zhang
- The Mental Health Center, Shantou University Medical College, China
| | - Qingjun Huang
- The Mental Health Center, Shantou University Medical College, China
| | - Zhiwei Shen
- The Department of Radiology, the second affiliated hospital, Shantou University Medical College, China
| | - Renhua Wu
- The Department of Radiology, the second affiliated hospital, Shantou University Medical College, China
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155
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Complex I assembly into supercomplexes determines differential mitochondrial ROS production in neurons and astrocytes. Proc Natl Acad Sci U S A 2016; 113:13063-13068. [PMID: 27799543 DOI: 10.1073/pnas.1613701113] [Citation(s) in RCA: 276] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Neurons depend on oxidative phosphorylation for energy generation, whereas astrocytes do not, a distinctive feature that is essential for neurotransmission and neuronal survival. However, any link between these metabolic differences and the structural organization of the mitochondrial respiratory chain is unknown. Here, we investigated this issue and found that, in neurons, mitochondrial complex I is predominantly assembled into supercomplexes, whereas in astrocytes the abundance of free complex I is higher. The presence of free complex I in astrocytes correlates with the severalfold higher reactive oxygen species (ROS) production by astrocytes compared with neurons. Using a complexomics approach, we found that the complex I subunit NDUFS1 was more abundant in neurons than in astrocytes. Interestingly, NDUFS1 knockdown in neurons decreased the association of complex I into supercomplexes, leading to impaired oxygen consumption and increased mitochondrial ROS. Conversely, overexpression of NDUFS1 in astrocytes promoted complex I incorporation into supercomplexes, decreasing ROS. Thus, complex I assembly into supercomplexes regulates ROS production and may contribute to the bioenergetic differences between neurons and astrocytes.
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156
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Langer J, Gerkau NJ, Derouiche A, Kleinhans C, Moshrefi-Ravasdjani B, Fredrich M, Kafitz KW, Seifert G, Steinhäuser C, Rose CR. Rapid sodium signaling couples glutamate uptake to breakdown of ATP in perivascular astrocyte endfeet. Glia 2016; 65:293-308. [PMID: 27785828 DOI: 10.1002/glia.23092] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/05/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022]
Abstract
Perivascular endfeet of astrocytes are highly polarized compartments that ensheath blood vessels and contribute to the blood-brain barrier. They experience calcium transients with neuronal activity, a phenomenon involved in neurovascular coupling. Endfeet also mediate the uptake of glucose from the blood, a process stimulated in active brain regions. Here, we demonstrate in mouse hippocampal tissue slices that endfeet undergo sodium signaling upon stimulation of glutamatergic synaptic activity. Glutamate-induced endfeet sodium transients were diminished by TFB-TBOA, suggesting that they were generated by sodium-dependent glutamate uptake. With local agonist application, they could be restricted to endfeet and immunohistochemical analysis revealed prominent expression of glutamate transporters GLAST and GLT-1 localized towards the neuropil vs. the vascular side of endfeet. Endfeet sodium signals spread at an apparent maximum velocity of ∼120 µm/s and directly propagated from stimulated into neighboring endfeet; this spread was omitted in Cx30/Cx43 double-deficient mice. Sodium transients resulted in elevation of intracellular magnesium, indicating a decrease in intracellular ATP. In summary, our results establish that excitatory synaptic activity and stimulation of glutamate uptake in astrocytes trigger transient sodium increases in perivascular endfeet which rapidly spread through gap junctions into neighboring endfeet and cause a reduction of intracellular ATP. The newly discovered endfeet sodium signaling thereby represents a fast, long-lived and inter-cellularly acting indicator of synaptic activity at the blood-brain barrier, which likely constitutes an important component of neuro-metabolic coupling in the brain. GLIA 2017;65:293-308.
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Affiliation(s)
- Julia Langer
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
| | - Niklas J Gerkau
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
| | - Amin Derouiche
- Institute of Anatomy II and Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-University of Frankfurt, Theodor-Stern-Kai 7, Frankfurt/M, D-60590, Germany
| | - Christian Kleinhans
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
| | - Behrouz Moshrefi-Ravasdjani
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
| | - Michaela Fredrich
- Institute of Anatomy II and Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-University of Frankfurt, Theodor-Stern-Kai 7, Frankfurt/M, D-60590, Germany
| | - Karl W Kafitz
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
| | - Gerald Seifert
- Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Bonn, D-53105, Germany
| | - Christian Steinhäuser
- Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Bonn, D-53105, Germany
| | - Christine R Rose
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Duesseldorf, Universitätsstrasse 1, Duesseldorf, D-40225, Germany
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157
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Cesconetto PA, Andrade CM, Cattani D, Domingues JT, Parisotto EB, Filho DW, Zamoner A. Maternal Exposure to Ethanol During Pregnancy and Lactation Affects Glutamatergic System and Induces Oxidative Stress in Offspring Hippocampus. Alcohol Clin Exp Res 2016; 40:52-61. [PMID: 26727523 DOI: 10.1111/acer.12917] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 09/28/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Alcohol abuse during pregnancy leads to intellectual disability and morphological defects in the offspring. The aim of this study was to determine the effect of chronic maternal ethanol (EtOH) consumption during pregnancy and lactation on glutamatergic transmission regulation, energy deficit, and oxidative stress in the hippocampus of the offspring. METHODS EtOH was administered to dams in drinking water at increasing doses (2 to 20%) from the gestation day 5 to lactation day 21. EtOH and tap water intake by treated and control groups, respectively, were measured daily. RESULTS Results showed that EtOH exposure does not affect fluid intake over the course of pregnancy and lactation. The toxicity of maternal exposure to EtOH was demonstrated by decreased offspring body weight at experimental age, on postnatal day 21. Moreover, maternal EtOH exposure decreased (45) Ca(2+) influx in the offspring's hippocampus. Corroborating this finding, EtOH increased both Na(+) -dependent and Na(+) -independent glial [(14) C]-glutamate uptake in hippocampus of immature rats. Also, maternal EtOH exposure decreased glutamine synthetase activity and induced aspartate aminotransferase enzymatic activity, suggesting that in EtOH-exposed offspring hippocampus, glutamate is preferentially used as a fuel in tricarboxylic acid cycle instead of being converted into glutamine. In addition, EtOH exposure decreased [U-14C]-2-deoxy-D-glucose uptake in offspring hippocampus. CONCLUSIONS The decline in glucose transport coincided with increased lactate dehydrogenase activity, suggesting an adaptative response in EtOH-exposed offspring hippocampus, using lactate as an alternative fuel. These events were associated with oxidative damage, as demonstrated by changes in the enzymatic antioxidant defense system and lipid peroxidation. Taken together, the results demonstrate that maternal exposure to EtOH during pregnancy and lactation impairs glutamatergic transmission, as well as inducing oxidative stress and energy deficit in immature rat hippocampus.
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Affiliation(s)
- Patricia A Cesconetto
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Camila M Andrade
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Daiane Cattani
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Juliana T Domingues
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Eduardo B Parisotto
- Departamento de Ecologia e Zoologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Danilo W Filho
- Departamento de Ecologia e Zoologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Ariane Zamoner
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
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158
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Role of glutamate receptors and glial cells in the pathophysiology of treatment-resistant depression. Prog Neuropsychopharmacol Biol Psychiatry 2016; 70:117-26. [PMID: 27046518 DOI: 10.1016/j.pnpbp.2016.03.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/27/2016] [Accepted: 03/29/2016] [Indexed: 02/07/2023]
Abstract
Treatment-resistant depression (TRD) causes substantial socioeconomic burden. Although a consensus on the definition of TRD has not yet been reached, it is certain that classic monoaminergic antidepressants are ineffective for TRD. One decade ago, many researchers found ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, to be an alternative to classic monoaminergic antidepressants. The major mechanisms of action of ketamine rapidly induce synaptogenesis in the brain-derived neurotrophic factor (BDNF) pathway. Although excessive glutamatergic neurotransmission and consequent excitotoxicity were considered a major cause of TRD, recent evidence suggests that the extrasynaptic glutamatergic receptor signal pathway mainly contributes to the detrimental effects of TRD. Glial cells such as microglia and astrocytes, early life adversity, and glucocorticoid receptor dysfunction participate in complex cross-talk. An appropriate reuptake of glutamate at the astrocyte is crucial for preventing 'spill-over' of synaptic glutamate and binding to the extrasynaptic NMDA receptor. Excessive microglial activation and the inflammatory process cause astrocyte glutamatergic dysfunction, which in turn activates microglial function. Early life adversity and glucocorticoid receptor dysfunction result in vulnerability to stress in adulthood. A maladaptive response to stress leads to increased glutamatergic release and pro-inflammatory cytokines, which then activate microglia. However, since the role of inflammatory mediators such as pro-inflammatory cytokines is not specific for depression, more disease-specific mechanisms should be identified. Last, although much research has focused on ketamine as an alternative antidepressant for TRD, its long-lasting effectiveness and adverse events have not been rigorously demonstrated. Additionally, evidence suggests that substantial brain abnormalities develop in ketamine abusers. Thus, more investigations for ketamine and other novel glutamatergic agents are needed.
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159
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Virkar YS, Shew WL, Restrepo JG, Ott E. Feedback control stabilization of critical dynamics via resource transport on multilayer networks: How glia enable learning dynamics in the brain. Phys Rev E 2016; 94:042310. [PMID: 27841512 DOI: 10.1103/physreve.94.042310] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Indexed: 06/06/2023]
Abstract
Learning and memory are acquired through long-lasting changes in synapses. In the simplest models, such synaptic potentiation typically leads to runaway excitation, but in reality there must exist processes that robustly preserve overall stability of the neural system dynamics. How is this accomplished? Various approaches to this basic question have been considered. Here we propose a particularly compelling and natural mechanism for preserving stability of learning neural systems. This mechanism is based on the global processes by which metabolic resources are distributed to the neurons by glial cells. Specifically, we introduce and study a model composed of two interacting networks: a model neural network interconnected by synapses that undergo spike-timing-dependent plasticity; and a model glial network interconnected by gap junctions that diffusively transport metabolic resources among the glia and, ultimately, to neural synapses where they are consumed. Our main result is that the biophysical constraints imposed by diffusive transport of metabolic resources through the glial network can prevent runaway growth of synaptic strength, both during ongoing activity and during learning. Our findings suggest a previously unappreciated role for glial transport of metabolites in the feedback control stabilization of neural network dynamics during learning.
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Affiliation(s)
- Yogesh S Virkar
- University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Woodrow L Shew
- University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Juan G Restrepo
- University of Colorado at Boulder, Boulder, Colorado 80309-0526, USA
| | - Edward Ott
- University of Maryland, College Park, Maryland 20742, USA
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160
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Theparambil SM, Weber T, Schmälzle J, Ruminot I, Deitmer JW. Proton Fall or Bicarbonate Rise: GLYCOLYTIC RATE IN MOUSE ASTROCYTES IS PAVED BY INTRACELLULAR ALKALINIZATION. J Biol Chem 2016; 291:19108-17. [PMID: 27422823 PMCID: PMC5009280 DOI: 10.1074/jbc.m116.730143] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/12/2016] [Indexed: 01/08/2023] Open
Abstract
Glycolysis is the primary step for major energy production in the cell. There is strong evidence suggesting that glucose consumption and rate of glycolysis are highly modulated by cytosolic pH/[H(+)], but those can also be stimulated by an increase in the intracellular [HCO3 (-)]. Because proton and bicarbonate shift concomitantly, it remained unclear whether enhanced glucose consumption and glycolytic rate were mediated by the changes in intracellular [H(+)] or [HCO3 (-)]. We have asked whether glucose metabolism is enhanced by either a fall in intracellular [H(+)] or a rise in intracellular [HCO3 (-)], or by both, in mammalian astrocytes. We have recorded intracellular glucose in mouse astrocytes using a FRET-based nanosensor, while imposing different intracellular [H(+)] and [CO2]/[HCO3 (-)]. Glucose consumption and glycolytic rate were augmented by a fall in intracellular [H(+)], irrespective of a concomitant rise or fall in intracellular [HCO3 (-)]. Transport of HCO3 (-) into and out of astrocytes by the electrogenic sodium bicarbonate cotransporter (NBCe1) played a crucial role in causing changes in intracellular pH and [HCO3 (-)], but was not obligatory for the pH-dependent changes in glucose metabolism. Our results clearly show that it is the cytosolic pH that modulates glucose metabolism in cortical astrocytes, and possibly also in other cell types.
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Affiliation(s)
- Shefeeq M Theparambil
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Tobias Weber
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Jana Schmälzle
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Ivàn Ruminot
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and the Centro de Estudios Científicos (CECs), Valdivia 5110466, Chile
| | - Joachim W Deitmer
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
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161
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Jurič DM, Kržan M, Lipnik-Stangelj M. Histamine and astrocyte function. Pharmacol Res 2016; 111:774-783. [DOI: 10.1016/j.phrs.2016.07.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/11/2016] [Accepted: 07/24/2016] [Indexed: 12/31/2022]
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162
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Wilkins HM, Swerdlow RH. Relationships Between Mitochondria and Neuroinflammation: Implications for Alzheimer's Disease. Curr Top Med Chem 2016; 16:849-57. [PMID: 26311426 DOI: 10.2174/1568026615666150827095102] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 06/03/2015] [Accepted: 07/30/2015] [Indexed: 01/05/2023]
Abstract
Mitochondrial dysfunction and neuroinflammation occur in Alzheimer's disease (AD). The causes of these pathologic lesions remain uncertain, but links between these phenomena are increasingly recognized. In this review, we discuss data that indicate mitochondria or mitochondrial components may contribute to neuroinflammation. While mitochondrial dysfunction could cause neuroinflammation, neuroinflammation could also cause mitochondrial dysfunction. However, based on the systemic nature of AD mitochondrial dysfunction as well as data from experiments we discuss, the former possibility is perhaps more likely. If correct, then manipulation of mitochondria, either directly or through manipulations of bioenergetic pathways, could prove effective in reducing metabolic dysfunction and neuroinflammation in AD patients. We also review some potential approaches through which such manipulations may be achieved.
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Affiliation(s)
| | - Russell H Swerdlow
- University of Kansas School of Medicine, MS 2012, Landon Center on Aging, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
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163
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Proia P, Di Liegro CM, Schiera G, Fricano A, Di Liegro I. Lactate as a Metabolite and a Regulator in the Central Nervous System. Int J Mol Sci 2016; 17:E1450. [PMID: 27598136 PMCID: PMC5037729 DOI: 10.3390/ijms17091450] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/22/2016] [Accepted: 08/25/2016] [Indexed: 12/21/2022] Open
Abstract
More than two hundred years after its discovery, lactate still remains an intriguing molecule. Considered for a long time as a waste product of metabolism and the culprit behind muscular fatigue, it was then recognized as an important fuel for many cells. In particular, in the nervous system, it has been proposed that lactate, released by astrocytes in response to neuronal activation, is taken up by neurons, oxidized to pyruvate and used for synthesizing acetyl-CoA to be used for the tricarboxylic acid cycle. More recently, in addition to this metabolic role, the discovery of a specific receptor prompted a reconsideration of its role, and lactate is now seen as a sort of hormone, even involved in processes as complex as memory formation and neuroprotection. As a matter of fact, exercise offers many benefits for our organisms, and seems to delay brain aging and neurodegeneration. Now, exercise induces the production and release of lactate into the blood which can reach the liver, the heart, and also the brain. Can lactate be a beneficial molecule produced during exercise, and offer neuroprotection? In this review, we summarize what we have known on lactate, discussing the roles that have been attributed to this molecule over time.
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Affiliation(s)
- Patrizia Proia
- Department of Psychological, Pedagogical and Educational Sciences, Sport and Exercise Sciences Research Unit, University of Palermo, Palermo I-90128, Italy.
| | - Carlo Maria Di Liegro
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Gabriella Schiera
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Anna Fricano
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Italia Di Liegro
- Department of Experimental Biomedicine and Clinical Neurosciences (BIONEC), University of Palermo, Palermo I-90127, Italy.
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164
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Disrupting astrocyte-neuron lactate transfer persistently reduces conditioned responses to cocaine. Mol Psychiatry 2016; 21:1070-6. [PMID: 26503760 PMCID: PMC4960452 DOI: 10.1038/mp.2015.157] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 08/11/2015] [Accepted: 09/08/2015] [Indexed: 01/14/2023]
Abstract
A central problem in the treatment of drug addiction is the high risk of relapse often precipitated by drug-associated cues. The transfer of glycogen-derived lactate from astrocytes to neurons is required for long-term memory. Whereas blockade of drug memory reconsolidation represents a potential therapeutic strategy, the role of astrocyte-neuron lactate transport in long-term conditioning has received little attention. By infusing an inhibitor of glycogen phosphorylase into the basolateral amygdala of rats, we report that disruption of astrocyte-derived lactate not only transiently impaired the acquisition of a cocaine-induced conditioned place preference but also persistently disrupted an established conditioning. The drug memory was rescued by L-Lactate co-administration through a mechanism requiring the synaptic plasticity-related transcription factor Zif268 and extracellular signal-regulated kinase (ERK) signalling pathway but not the brain-derived neurotrophic factor (Bdnf). The long-term amnesia induced by glycogenolysis inhibition and the concomitant decreased expression of phospho-ERK were both restored with L-Lactate co-administration. These findings reveal a critical role for astrocyte-derived lactate in positive memory formation and highlight a novel amygdala-dependent reconsolidation process, whose disruption may offer a novel therapeutic target to reduce the long-lasting conditioned responses to cocaine.
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165
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Patak J, Hess JL, Zhang-James Y, Glatt SJ, Faraone SV. SLC9A9 Co-expression modules in autism-associated brain regions. Autism Res 2016; 10:414-429. [PMID: 27439572 DOI: 10.1002/aur.1670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 12/16/2022]
Abstract
SLC9A9 is a sodium hydrogen exchanger present in the recycling endosome and highly expressed in the brain. It is implicated in neuropsychiatric disorders, including autism spectrum disorders (ASDs). Little research concerning its gene expression patterns and biological pathways has been conducted. We sought to investigate its possible biological roles in autism-associated brain regions throughout development. We conducted a weighted gene co-expression network analysis on RNA-seq data downloaded from Brainspan. We compared prenatal and postnatal gene expression networks for three ASD-associated brain regions known to have high SLC9A9 gene expression. We also performed an ASD-associated single nucleotide polymorphism enrichment analysis and a cell signature enrichment analysis. The modules showed differences in gene constituents (membership), gene number, and connectivity throughout time. SLC9A9 was highly associated with immune system functions, metabolism, apoptosis, endocytosis, and signaling cascades. Gene list comparison with co-immunoprecipitation data was significant for multiple modules. We found a disproportionately high autism risk signal among genes constituting the prenatal hippocampal module. The modules were enriched with astrocyte and oligodendrocyte markers. SLC9A9 is potentially involved in the pathophysiology of ASDs. Our investigation confirmed proposed functions for SLC9A9, such as endocytosis and immune regulation, while also revealing potential roles in mTOR signaling and cell survival.. By providing a concise molecular map and interactions, evidence of cell type and implicated brain regions we hope this will guide future research on SLC9A9. Autism Res 2017, 10: 414-429. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.
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Affiliation(s)
- Jameson Patak
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York
| | - Jonathan L Hess
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York
| | - Yanli Zhang-James
- Department of Psychiatry, Upstate Medical University, Syracuse, New York
| | - Stephen J Glatt
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York.,Department of Psychiatry, Upstate Medical University, Syracuse, New York
| | - Stephen V Faraone
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York.,Department of Psychiatry, Upstate Medical University, Syracuse, New York.,Department of Biomedicine, K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
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166
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Zhang Y, Xue Y, Meng S, Luo Y, Liang J, Li J, Ai S, Sun C, Shen H, Zhu W, Wu P, Lu L, Shi J. Inhibition of Lactate Transport Erases Drug Memory and Prevents Drug Relapse. Biol Psychiatry 2016; 79:928-39. [PMID: 26293178 DOI: 10.1016/j.biopsych.2015.07.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/23/2015] [Accepted: 07/10/2015] [Indexed: 12/31/2022]
Abstract
BACKGROUND Drug memories that associate drug-paired stimuli with the effects of abused drugs contribute to relapse. Exposure to drug-associated contexts causes consolidated drug memories to be in a labile state, during which manipulations can be given to impair drug memories. Although substantial evidence demonstrates the crucial role of neuronal signaling in addiction, little is known about the contribution of astrocyte-neuron communication. METHODS Rats were trained for cocaine-induced conditioned place preference (CPP) or self-administration and microinjected with the glycogen phosphorylation inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol into the basolateral amygdala (BLA) immediately after retrieval. The concentration of lactate was measured immediately after retrieval via microdialysis, and the CPP score and number of nosepokes were recorded 24 hours later. Furthermore, we used antisense oligodeoxynucleotides to disrupt the expression of astrocytic lactate transporters (monocarboxylate transporters 1 and 2) in the BLA after retrieval, tested the expression of CPP 1 day later, and injected L-lactate into the BLA 15 minutes before retrieval to rescue the effects of the oligodeoxynucleotides. RESULTS Injection of 1,4-dideoxy-1,4-imino-D-arabinitol into the BLA immediately after retrieval prevented the subsequent expression of cocaine-induced CPP, decreased the concentration of lactate in the BLA, and reduced the number of nosepokes for cocaine self-administration. Disrupting the expression of monocarboxylate transporters 1 and 2 in the BLA also caused subsequent deficits in the expression of cocaine-induced CPP, which was rescued by pretreatment with L-lactate. CONCLUSIONS Our results suggest that astrocyte-neuron lactate transport in the BLA is critical for the reconsolidation of cocaine memory.
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Affiliation(s)
- Yan Zhang
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Yanxue Xue
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Shiqiu Meng
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Yixiao Luo
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Jie Liang
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Jiali Li
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Sizhi Ai
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Chengyu Sun
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Haowei Shen
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Weili Zhu
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Ping Wu
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China
| | - Lin Lu
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China; Institute of Mental Health/Peking University Sixth Hospital and Key Laboratory of Mental Health, Beijing, China; Peking-Tsinghua Center for Life Sciences and Peking University-International Data Group/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Jie Shi
- National Institute on Drug Dependence and Beijing Key Laboratory on Drug Dependence Research, Beijing, China.
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167
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Jha MK, Lee IK, Suk K. Metabolic reprogramming by the pyruvate dehydrogenase kinase-lactic acid axis: Linking metabolism and diverse neuropathophysiologies. Neurosci Biobehav Rev 2016; 68:1-19. [PMID: 27179453 DOI: 10.1016/j.neubiorev.2016.05.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/11/2016] [Accepted: 05/09/2016] [Indexed: 12/12/2022]
Abstract
Emerging evidence indicates that there is a complex interplay between metabolism and chronic disorders in the nervous system. In particular, the pyruvate dehydrogenase (PDH) kinase (PDK)-lactic acid axis is a critical link that connects metabolic reprogramming and the pathophysiology of neurological disorders. PDKs, via regulation of PDH complex activity, orchestrate the conversion of pyruvate either aerobically to acetyl-CoA, or anaerobically to lactate. The kinases are also involved in neurometabolic dysregulation under pathological conditions. Lactate, an energy substrate for neurons, is also a recently acknowledged signaling molecule involved in neuronal plasticity, neuron-glia interactions, neuroimmune communication, and nociception. More recently, the PDK-lactic acid axis has been recognized to modulate neuronal and glial phenotypes and activities, contributing to the pathophysiologies of diverse neurological disorders. This review covers the recent advances that implicate the PDK-lactic acid axis as a novel linker of metabolism and diverse neuropathophysiologies. We finally explore the possibilities of employing the PDK-lactic acid axis and its downstream mediators as putative future therapeutic strategies aimed at prevention or treatment of neurological disorders.
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Affiliation(s)
- Mithilesh Kumar Jha
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea; Department of Neurology, Division of Neuromuscular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - In-Kyu Lee
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
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168
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Parpura V, Sekler I, Fern R. Plasmalemmal and mitochondrial Na+-Ca2+exchange in neuroglia. Glia 2016; 64:1646-54. [DOI: 10.1002/glia.22975] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 01/07/2016] [Accepted: 01/25/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology; Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham; Birmingham Alabama
| | - Israel Sekler
- Department of Physiology, Faculty of Health Science; Ben-Gurion University; Ben-Guion Av 84105 POB 653
| | - Robert Fern
- Peninsular School of Medicine and Dentistry; University of Plymouth; Plymouth PL6 8BU United Kingdom
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169
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Baud MO, Parafita J, Nguyen A, Magistretti PJ, Petit JM. Sleep fragmentation alters brain energy metabolism without modifying hippocampal electrophysiological response to novelty exposure. J Sleep Res 2016; 25:583-590. [PMID: 27136914 DOI: 10.1111/jsr.12419] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 02/13/2016] [Indexed: 02/06/2023]
Abstract
Sleep is viewed as a fundamental restorative function of the brain, but its specific role in neural energy budget remains poorly understood. Sleep deprivation dampens brain energy metabolism and impairs cognitive functions. Intriguingly, sleep fragmentation, despite normal total sleep duration, has a similar cognitive impact, and in this paper we ask the question of whether it may also impair brain energy metabolism. To this end, we used a recently developed mouse model of 2 weeks of sleep fragmentation and measured 2-deoxy-glucose uptake and glycogen, glucose and lactate concentration in different brain regions. In order to homogenize mice behaviour during metabolic measurements, we exposed them to a novel environment for 1 h. Using an intra-hippocampal electrode, we first showed that hippocampal electroencephalograph (EEG) response to exploration was unaltered by 1 or 14 days of sleep fragmentation. However, after 14 days, sleep fragmented mice exhibited a lower uptake of 2-deoxy-glucose in cortex and hippocampus and lower cortical lactate levels than control mice. Our results suggest that long-term sleep fragmentation impaired brain metabolism to a similar extent as total sleep deprivation without affecting the neuronal responsiveness of hippocampus to a novel environment.
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Affiliation(s)
- Maxime O Baud
- LNDC, Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Department of Neurology, UCSF, San Francisco, CA, USA
| | - Julia Parafita
- LNDC, Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Audrey Nguyen
- LNDC, Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Pierre J Magistretti
- LNDC, Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,BESE Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.,Centre de Neurosciences Psychiatriques, Centre Hospitalier Universitaire Vaudois (CHUV), Prilly, Switzerland
| | - Jean-Marie Petit
- LNDC, Brain Mind Institute, Faculté des Sciences de la Vie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland. .,Centre de Neurosciences Psychiatriques, Centre Hospitalier Universitaire Vaudois (CHUV), Prilly, Switzerland.
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170
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Oliveira da Cruz J, Robin L, Drago F, Marsicano G, Metna-Laurent M. Astroglial type-1 cannabinoid receptor (CB1): A new player in the tripartite synapse. Neuroscience 2016; 323:35-42. [DOI: 10.1016/j.neuroscience.2015.05.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/25/2015] [Accepted: 05/01/2015] [Indexed: 01/08/2023]
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171
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Herwerth M, Kalluri SR, Srivastava R, Kleele T, Kenet S, Illes Z, Merkler D, Bennett JL, Misgeld T, Hemmer B. In vivo imaging reveals rapid astrocyte depletion and axon damage in a model of neuromyelitis optica-related pathology. Ann Neurol 2016; 79:794-805. [PMID: 26946517 PMCID: PMC5021140 DOI: 10.1002/ana.24630] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 01/27/2023]
Abstract
Objective Neuromyelitis optica (NMO) is an autoimmune disease of the central nervous system, which resembles multiple sclerosis (MS). NMO differs from MS, however, in the distribution and histology of neuroinflammatory lesions and shows a more aggressive clinical course. Moreover, the majority of NMO patients carry immunoglobulin G autoantibodies against aquaporin‐4 (AQP4), an astrocytic water channel. Antibodies against AQP4 can damage astrocytes by complement, but NMO histopathology also shows demyelination, and — importantly—axon injury, which may determine permanent deficits following NMO relapses. The dynamics of astrocyte injury in NMO and the mechanisms by which toxicity spreads to axons are not understood. Methods Here, we establish in vivo imaging of the spinal cord, one of the main sites of NMO pathology, as a powerful tool to study the formation of experimental NMO‐related lesions caused by human AQP4 antibodies in mice. Results We found that human AQP4 antibodies caused acute astrocyte depletion with initial oligodendrocyte survival. Within 2 hours of antibody application, we observed secondary axon injury in the form of progressive swellings. Astrocyte toxicity and axon damage were dependent on AQP4 antibody titer and complement, specifically C1q. Interpretation In vivo imaging of the spinal cord reveals the swift development of NMO‐related acute axon injury after AQP4 antibody‐mediated astrocyte depletion. This approach will be useful in studying the mechanisms underlying the spread of NMO pathology beyond astrocytes, as well as in evaluating potential neuroprotective interventions. Ann Neurol 2016;79:794–805
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Affiliation(s)
- Marina Herwerth
- Department of Neurology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.,Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Sudhakar Reddy Kalluri
- Department of Neurology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Rajneesh Srivastava
- Department of Neurology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Tatjana Kleele
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany
| | - Selin Kenet
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany
| | - Zsolt Illes
- Department of Neurology, Division of Clinical and Experimental Neuroimmunology, University of Pecs, Pecs, Hungary.,Department of Neurology and Institute of Clinical Research, Odense University Hospital, University of Southern Denmark, Odense, Denmark
| | - Doron Merkler
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland.,Division of Clinical Pathology, Geneva University Hospital, Geneva, Switzerland.,Department of Neuropathology, University Medical Center, Göttingen, Germany
| | - Jeffrey L Bennett
- Departments of Neurology and Ophthalmology, Program in Neuroscience, University of Colorado Denver School of Medicine, Aurora, CO
| | - Thomas Misgeld
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Center of Integrated Protein Science (CIPSM), Munich, Germany.,equal contributing senior authors
| | - Bernhard Hemmer
- Department of Neurology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,equal contributing senior authors
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172
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Bolaños JP. Bioenergetics and redox adaptations of astrocytes to neuronal activity. J Neurochem 2016; 139 Suppl 2:115-125. [PMID: 26968531 PMCID: PMC5018236 DOI: 10.1111/jnc.13486] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/19/2015] [Accepted: 11/23/2015] [Indexed: 12/14/2022]
Abstract
Neuronal activity is a high‐energy demanding process recruiting all neural cells that adapt their metabolism to sustain the energy and redox balance of neurons. During neurotransmission, synaptic cleft glutamate activates its receptors in neurons and in astrocytes, before being taken up by astrocytes through energy costly transporters. In astrocytes, the energy requirement for glutamate influx is likely to be met by glycolysis. To enable this, astrocytes are constitutively glycolytic, robustly expressing 6‐phosphofructo‐2‐kinase/fructose‐2,6‐bisphosphatase‐3 (PFKFB3), an enzyme that is negligibly present in neurons by continuous degradation because of the ubiquitin‐proteasome pathway via anaphase‐promoting complex/cyclosome (APC)‐Cdh1. Additional factors contributing to the glycolytic frame of astrocytes may include 5′‐AMP‐activated protein kinase (AMPK), hypoxia‐inducible factor‐1 (HIF‐1), pyruvate kinase muscle isoform‐2 (PKM2), pyruvate dehydrogenase kinase‐4 (PDK4), lactate dehydrogenase‐B, or monocarboxylate transporter‐4 (MCT4). Neurotransmission‐associated messengers, such as nitric oxide or ammonium, stimulate lactate release from astrocytes. Astrocyte‐derived glycolytic lactate thus sustains the energy needs of neurons, which in contrast to astrocytes mainly rely on oxidative phosphorylation. Neuronal activity unavoidably triggers reactive oxygen species, but the antioxidant defense of neurons is weak; hence, they use glucose for oxidation through the pentose‐phosphate pathway to preserve the redox status. Furthermore, neural activity is coupled with erythroid‐derived erythroid‐derived 2‐like 2 (Nrf2) mediated transcriptional activation of antioxidant genes in astrocytes, which boost the de novo glutathione biosynthesis in neighbor neurons. Thus, the bioenergetics and redox programs of astrocytes are adapted to sustain neuronal activity and survival. Developing therapeutic strategies to interfere with these pathways may be useful to combat neurological diseases.
Our current knowledge on brain's management of bioenergetics and redox requirements associated with neural activity is herein revisited. The astrocyte‐neuronal lactate shuttle (ANLS) explains the energy needs of neurotransmission. Furthermore, neurotransmission unavoidably triggers increased mitochondrial reactive oxygen species in neurons. By coupling glutamatergic activity with transcriptional activation of antioxidant genes, astrocytes provide neurons with neuroprotective glutathione through an astrocyte‐neuronal glutathione shuttle (ANGS).
This article is part of the60th Anniversary special issue.
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Affiliation(s)
- Juan P Bolaños
- Institute of Functional Biology and Genomics (IBFG), University of Salamanca-CSIC-IBSAL, Salamanca, Spain.
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173
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Dallérac G, Rouach N. Astrocytes as new targets to improve cognitive functions. Prog Neurobiol 2016; 144:48-67. [PMID: 26969413 DOI: 10.1016/j.pneurobio.2016.01.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/07/2016] [Accepted: 01/24/2016] [Indexed: 01/09/2023]
Abstract
Astrocytes are now viewed as key elements of brain wiring as well as neuronal communication. Indeed, they not only bridge the gap between metabolic supplies by blood vessels and neurons, but also allow fine control of neurotransmission by providing appropriate signaling molecules and insulation through a tight enwrapping of synapses. Recognition that astroglia is essential to neuronal communication is nevertheless fairly recent and the large body of evidence dissecting such role has focused on the synaptic level by identifying neuro- and gliotransmitters uptaken and released at synaptic or extrasynaptic sites. Yet, more integrated research deciphering the impact of astroglial functions on neuronal network activity have led to the reasonable assumption that the role of astrocytes in supervising synaptic activity translates in influencing neuronal processing and cognitive functions. Several investigations using recent genetic tools now support this notion by showing that inactivating or boosting astroglial function directly affects cognitive abilities. Accordingly, brain diseases resulting in impaired cognitive functions have seen their physiopathological mechanisms revisited in light of this primary protagonist of brain processing. We here provide a review of the current knowledge on the role of astrocytes in cognition and in several brain diseases including neurodegenerative disorders, psychiatric illnesses, as well as other conditions such as epilepsy. Potential astroglial therapeutic targets are also discussed.
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Affiliation(s)
- Glenn Dallérac
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France.
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France.
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174
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Steinman MQ, Gao V, Alberini CM. The Role of Lactate-Mediated Metabolic Coupling between Astrocytes and Neurons in Long-Term Memory Formation. Front Integr Neurosci 2016; 10:10. [PMID: 26973477 PMCID: PMC4776217 DOI: 10.3389/fnint.2016.00010] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/15/2016] [Indexed: 01/07/2023] Open
Abstract
Long-term memory formation, the ability to retain information over time about an experience, is a complex function that affects multiple behaviors, and is an integral part of an individual's identity. In the last 50 years many scientists have focused their work on understanding the biological mechanisms underlying memory formation and processing. Molecular studies over the last three decades have mostly investigated, or given attention to, neuronal mechanisms. However, the brain is composed of different cell types that, by concerted actions, cooperate to mediate brain functions. Here, we consider some new insights that emerged from recent studies implicating astrocytic glycogen and glucose metabolisms, and particularly their coupling to neuronal functions via lactate, as an essential mechanism for long-term memory formation.
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Affiliation(s)
| | - Virginia Gao
- Center for Neural Science, New York University New York, NY, USA
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175
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Lemos C, Rial D, Gonçalves F, Pires J, Silva H, Matheus F, da Silva A, Marques J, Rodrigues R, Jarak I, Prediger R, Reis F, Carvalho R, Pereira F, Cunha R. High sucrose consumption induces memory impairment in rats associated with electrophysiological modifications but not with metabolic changes in the hippocampus. Neuroscience 2016; 315:196-205. [DOI: 10.1016/j.neuroscience.2015.12.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/08/2015] [Accepted: 12/10/2015] [Indexed: 12/20/2022]
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176
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Monocarboxylate transporter 4 as a prognostic biomarker in patients with colorectal cancer and liver metastases. INTERNATIONAL JOURNAL OF SURGERY OPEN 2016. [DOI: 10.1016/j.ijso.2016.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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177
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Tyler CW, Likova LT, Nicholas SC. Analysis of Neural-BOLD Coupling Through Four Models of the Neural Metabolic Demand. Front Neurosci 2015; 9:419. [PMID: 26696806 PMCID: PMC4678231 DOI: 10.3389/fnins.2015.00419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 10/16/2015] [Indexed: 01/13/2023] Open
Abstract
The coupling of the neuronal energetics to the blood-oxygen-level-dependent (BOLD) response is still incompletely understood. To address this issue, we compared the fits of four plausible models of neurometabolic coupling dynamics to available data for simultaneous recordings of the local field potential and the local BOLD response recorded from monkey primary visual cortex over a wide range of stimulus durations. The four models of the metabolic demand driving the BOLD response were: direct coupling with the overall LFP; rectified coupling to the LFP; coupling with a slow adaptive component of the implied neural population response; and coupling with the non-adaptive intracellular input signal defined by the stimulus time course. Taking all stimulus durations into account, the results imply that the BOLD response is most closely coupled with metabolic demand derived from the intracellular input waveform, without significant influence from the adaptive transients and nonlinearities exhibited by the LFP waveform.
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178
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Sladek CD, Stevens W, Song Z, Johnson GC, MacLean PS. The "metabolic sensor" function of rat supraoptic oxytocin and vasopressin neurons is attenuated during lactation but not in diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 2015; 310:R337-45. [PMID: 26661099 DOI: 10.1152/ajpregu.00422.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/07/2015] [Indexed: 12/14/2022]
Abstract
The oxytocin (OT) and vasopressin (VP) neurons of the supraoptic nucleus (SON) demonstrate characteristics of "metabolic sensors". They express insulin receptors and glucokinase (GK). They respond to an increase in glucose and insulin with an increase in intracellular [Ca(2+)] and increased OT and VP release that is GK dependent. Although this is consistent with the established role of OT as an anorectic agent, how these molecules function relative to the important role of OT during lactation and whether deficits in this metabolic sensor function contribute to obesity remain to be examined. Thus, we evaluated whether insulin and glucose-induced OT and VP secretion from perifused explants of the hypothalamo-neurohypophyseal system are altered during lactation and by diet-induced obesity (DIO). In explants from female day 8 lactating rats, increasing glucose (Glu, 5 mM) did not alter OT or VP release. However, insulin (Ins; 3 ng/ml) increased OT release, and increasing the glucose concentration in the presence of insulin (Ins+Glu) resulted in a sustained elevation in both OT and VP release that was not prevented by alloxan, a GK inhibitor. Explants from male DIO rats also responded to Ins+Glu with an increase in OT and VP regardless of whether obesity had been induced by feeding a high-fat diet (HFD). The HFD-DIO rats had elevated body weight, plasma Ins, Glu, leptin, and triglycerides. These findings suggest that the role of SON neurons as metabolic sensors is diminished during lactation, but not in this animal model of obesity.
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Affiliation(s)
- Celia D Sladek
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Wanida Stevens
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Zhilin Song
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Ginger C Johnson
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Paul S MacLean
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
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179
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Abstract
Cortical electroencephalographic activity arises from corticothalamocortical interactions, modulated by wake-promoting monoaminergic and cholinergic input. These wake-promoting systems are regulated by hypothalamic hypocretin/orexins, while GABAergic sleep-promoting nuclei are found in the preoptic area, brainstem and lateral hypothalamus. Although pontine acetylcholine is critical for REM sleep, hypothalamic melanin-concentrating hormone/GABAergic cells may "gate" REM sleep. Daily sleep-wake rhythms arise from interactions between a hypothalamic circadian pacemaker and a sleep homeostat whose anatomical locus has yet to be conclusively defined. Control of sleep and wakefulness involves multiple systems, each of which presents vulnerability to sleep/wake dysfunction that may predispose to physical and/or neuropsychiatric disorders.
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Affiliation(s)
- Michael D Schwartz
- Biosciences Division, Center for Neuroscience, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Thomas S Kilduff
- Biosciences Division, Center for Neuroscience, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA.
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180
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Wilson CL, Natarajan V, Hayward SL, Khalimonchuk O, Kidambi S. Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles. NANOSCALE 2015; 7:18477-88. [PMID: 26274697 PMCID: PMC4636459 DOI: 10.1039/c5nr03646a] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Titanium dioxide (TiO2) nanoparticles are currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTracker® Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 ± 10.56 ppm, 136.0 ± 31.73 ppm and 62.37 ± 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of a loss in vital astrocyte function. TiO2 nanoparticles also induced an increase in reactive oxygen species generation, and a decrease in mitochondrial membrane potential, suggesting mitochondrial damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticle exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticle exposure has potential implications in astrocyte-mediated neurological dysfunction.
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Affiliation(s)
- Christina L Wilson
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, NE 68588, USA.
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181
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E L, Swerdlow RH. Lactate's effect on human neuroblastoma cell bioenergetic fluxes. Biochem Pharmacol 2015; 99:88-100. [PMID: 26592660 DOI: 10.1016/j.bcp.2015.11.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/02/2015] [Indexed: 12/12/2022]
Abstract
Lactate, once considered a metabolic dead-end, has been recently proposed to support neuron bioenergetics. To better understand how lactate specifically influences cell energy metabolism, we studied the effects of lactate supplementation on SH-SY5Y human neuroblastoma cell bioenergetic fluxes. Lactate supplementation increased cell respiration, there was no change in respiratory coupling efficiency, and lactate itself appeared to directly support the respiratory flux increase. Conversely, lactate supplementation reduced the glycolysis flux. This apparent pro-aerobic shift in the respiration:glycolysis ratio was accompanied by post-translational modifications and compartmental redistributions of proteins that respond to and modify bioenergetic fluxes, including cAMP-response element binding protein (CREB), p38 mitogen-activated protein kinases (p38 MAPK), AMP-activated protein kinase (AMPK), peroxisome-proliferator activated receptor gamma coactivator 1 β (PGC-1β), Akt, mammalian target of rapamycin (mTOR), and forkhead box protein O1 (FOXO1). mRNA levels for PGC-1β, nuclear respiratory factor 1 (NRF1), and cytochrome c oxidase subunit 1 (COX1) increased. Some effects depended on the direct presence of lactate, while others were durable and evident several hours after lactate was removed. We conclude lactate can be used to manipulate cell bioenergetics.
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Affiliation(s)
- Lezi E
- Department of Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, KS, USA; Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Russell H Swerdlow
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA; Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA; University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Kansas City, KS, USA.
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182
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Astrocyte-mediated metaplasticity in the hippocampus: Help or hindrance? Neuroscience 2015; 309:113-24. [DOI: 10.1016/j.neuroscience.2015.08.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 08/03/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022]
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183
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Falkowska A, Gutowska I, Goschorska M, Nowacki P, Chlubek D, Baranowska-Bosiacka I. Energy Metabolism of the Brain, Including the Cooperation between Astrocytes and Neurons, Especially in the Context of Glycogen Metabolism. Int J Mol Sci 2015; 16:25959-81. [PMID: 26528968 PMCID: PMC4661798 DOI: 10.3390/ijms161125939] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/27/2015] [Accepted: 10/16/2015] [Indexed: 01/15/2023] Open
Abstract
Glycogen metabolism has important implications for the functioning of the brain, especially the cooperation between astrocytes and neurons. According to various research data, in a glycogen deficiency (for example during hypoglycemia) glycogen supplies are used to generate lactate, which is then transported to neighboring neurons. Likewise, during periods of intense activity of the nervous system, when the energy demand exceeds supply, astrocyte glycogen is immediately converted to lactate, some of which is transported to the neurons. Thus, glycogen from astrocytes functions as a kind of protection against hypoglycemia, ensuring preservation of neuronal function. The neuroprotective effect of lactate during hypoglycemia or cerebral ischemia has been reported in literature. This review goes on to emphasize that while neurons and astrocytes differ in metabolic profile, they interact to form a common metabolic cooperation.
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Affiliation(s)
- Anna Falkowska
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Powstańców Wlkp. 72, 70-111 Szczecin, Poland.
| | - Izabela Gutowska
- Department of Biochemistry and Human Nutrition, Pomeranian Medical University, Broniewskiego 24, 71-460 Szczecin, Poland.
| | - Marta Goschorska
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Powstańców Wlkp. 72, 70-111 Szczecin, Poland.
| | - Przemysław Nowacki
- Department of Neurology, Pomeranian Medical University, Unii Lubelskiej 1, 71-225 Szczecin, Poland.
| | - Dariusz Chlubek
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Powstańców Wlkp. 72, 70-111 Szczecin, Poland.
| | - Irena Baranowska-Bosiacka
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Powstańców Wlkp. 72, 70-111 Szczecin, Poland.
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184
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Abstract
In terrestrial mammals, the oxygen storage capacity of the CNS is limited, and neuronal function is rapidly impaired if oxygen supply is interrupted even for a short period of time. However, oxygen tension monitored by the peripheral (arterial) chemoreceptors is not sensitive to regional CNS differences in partial pressure of oxygen (PO2 ) that reflect variable levels of neuronal activity or local tissue hypoxia, pointing to the necessity of a functional brain oxygen sensor. This experimental animal (rats and mice) study shows that astrocytes, the most numerous brain glial cells, are sensitive to physiological changes in PO2 . Astrocytes respond to decreases in PO2 a few millimeters of mercury below normal brain oxygenation with elevations in intracellular calcium ([Ca(2+)]i). The hypoxia sensor of astrocytes resides in the mitochondria in which oxygen is consumed. Physiological decrease in PO2 inhibits astroglial mitochondrial respiration, leading to mitochondrial depolarization, production of free radicals, lipid peroxidation, activation of phospholipase C, IP3 receptors, and release of Ca(2+) from the intracellular stores. Hypoxia-induced [Ca(2+)]i increases in astrocytes trigger fusion of vesicular compartments containing ATP. Blockade of astrocytic signaling by overexpression of ATP-degrading enzymes or targeted astrocyte-specific expression of tetanus toxin light chain (to interfere with vesicular release mechanisms) within the brainstem respiratory rhythm-generating circuits reveals the fundamental physiological role of astroglial oxygen sensitivity; in low-oxygen conditions (environmental hypoxia), this mechanism increases breathing activity even in the absence of peripheral chemoreceptor oxygen sensing. These results demonstrate that astrocytes are functionally specialized CNS oxygen sensors tuned for rapid detection of physiological changes in brain oxygenation. Significance statement: Most, if not all, animal cells possess mechanisms that allow them to detect decreases in oxygen availability leading to slow-timescale, adaptive changes in gene expression and cell physiology. To date, only two types of mammalian cells have been demonstrated to be specialized for rapid functional oxygen sensing: glomus cells of the carotid body (peripheral respiratory chemoreceptors) that stimulate breathing when oxygenation of the arterial blood decreases; and pulmonary arterial smooth muscle cells responsible for hypoxic pulmonary vasoconstriction to limit perfusion of poorly ventilated regions of the lungs. Results of the present study suggest that there is another specialized oxygen-sensitive cell type in the body, the astrocyte, that is tuned for rapid detection of physiological changes in brain oxygenation.
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185
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Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity. Brain Topogr 2015; 29:243-52. [DOI: 10.1007/s10548-015-0453-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/26/2015] [Indexed: 10/23/2022]
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186
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Preferential reduction of synaptic efficacy in the dentate gyrus of hippocampal slices from aged rats during reduced glucose availability. Neuroscience 2015; 307:262-72. [DOI: 10.1016/j.neuroscience.2015.08.065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 11/18/2022]
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187
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Rasband MN. Glial Contributions to Neural Function and Disease. Mol Cell Proteomics 2015; 15:355-61. [PMID: 26342039 DOI: 10.1074/mcp.r115.053744] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Indexed: 12/31/2022] Open
Abstract
The nervous system consists of neurons and glial cells. Neurons generate and propagate electrical and chemical signals, whereas glia function mainly to modulate neuron function and signaling. Just as there are many different kinds of neurons with different roles, there are also many types of glia that perform diverse functions. For example, glia make myelin; modulate synapse formation, function, and elimination; regulate blood flow and metabolism; and maintain ionic and water homeostasis to name only a few. Although proteomic approaches have been used extensively to understand neurons, the same cannot be said for glia. Importantly, like neurons, glial cells have unique protein compositions that reflect their diverse functions, and these compositions can change depending on activity or disease. Here, I discuss the major classes and functions of glial cells in the central and peripheral nervous systems. I describe proteomic approaches that have been used to investigate glial cell function and composition and the experimental limitations faced by investigators working with glia.
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Affiliation(s)
- Matthew N Rasband
- From the Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
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188
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Laskowska-Macios K, Nys J, Hu TT, Zapasnik M, Van der Perren A, Kossut M, Burnat K, Arckens L. Binocular pattern deprivation interferes with the expression of proteins involved in primary visual cortex maturation in the cat. Mol Brain 2015; 8:48. [PMID: 26271461 PMCID: PMC4536594 DOI: 10.1186/s13041-015-0137-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 07/31/2015] [Indexed: 12/03/2022] Open
Abstract
Background Binocular pattern deprivation from eye opening (early BD) delays the maturation of the primary visual cortex. This delay is more pronounced for the peripheral than the central visual field representation within area 17, particularly between the age of 2 and 4 months [Laskowska-Macios, Cereb Cortex, 2014]. Results In this study, we probed for related dynamic changes in the cortical proteome. We introduced age, cortical region and BD as principal variables in a 2-D DIGE screen of area 17. In this way we explored the potential of BD-related protein expression changes between central and peripheral area 17 of 2- and 4-month-old BD (2BD, 4BD) kittens as a valid parameter towards the identification of brain maturation-related molecular processes. Consistent with the maturation delay, distinct developmental protein expression changes observed for normal kittens were postponed by BD, especially in the peripheral region. These BD-induced proteomic changes suggest a negative regulation of neurite outgrowth, synaptic transmission and clathrin-mediated endocytosis, thereby implicating these processes in normal experience-induced visual cortex maturation. Verification of the expression of proteins from each of the biological processes via Western analysis disclosed that some of the transient proteomic changes correlate to the distinct behavioral outcome in adult life, depending on timing and duration of the BD period [Neuroscience 2013;255:99-109]. Conclusions Taken together, the plasticity potential to recover from BD, in relation to ensuing restoration of normal visual input, appears to rely on specific protein expression changes and cellular processes induced by the loss of pattern vision in early life. Electronic supplementary material The online version of this article (doi:10.1186/s13041-015-0137-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Karolina Laskowska-Macios
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, 02-093, Warsaw, Poland. .,Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
| | - Julie Nys
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
| | - Tjing-Tjing Hu
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
| | - Monika Zapasnik
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, 02-093, Warsaw, Poland.
| | - Anke Van der Perren
- Laboratory for Neurobiology and Gene Therapy, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
| | - Malgorzata Kossut
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, 02-093, Warsaw, Poland.
| | - Kalina Burnat
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, 02-093, Warsaw, Poland.
| | - Lutgarde Arckens
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
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189
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Magistretti PJ, Allaman I. A cellular perspective on brain energy metabolism and functional imaging. Neuron 2015; 86:883-901. [PMID: 25996133 DOI: 10.1016/j.neuron.2015.03.035] [Citation(s) in RCA: 744] [Impact Index Per Article: 82.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The energy demands of the brain are high: they account for at least 20% of the body's energy consumption. Evolutionary studies indicate that the emergence of higher cognitive functions in humans is associated with an increased glucose utilization and expression of energy metabolism genes. Functional brain imaging techniques such as fMRI and PET, which are widely used in human neuroscience studies, detect signals that monitor energy delivery and use in register with neuronal activity. Recent technological advances in metabolic studies with cellular resolution have afforded decisive insights into the understanding of the cellular and molecular bases of the coupling between neuronal activity and energy metabolism and point at a key role of neuron-astrocyte metabolic interactions. This article reviews some of the most salient features emerging from recent studies and aims at providing an integration of brain energy metabolism across resolution scales.
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Affiliation(s)
- Pierre J Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia; Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland; Center for Psychiatric Neurosciences, Department of Psychiatry, University of Lausanne, Lausanne 1008, Switzerland.
| | - Igor Allaman
- Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
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190
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Rama Rao KV, Kielian T. Neuron-astrocyte interactions in neurodegenerative diseases: Role of neuroinflammation. ACTA ACUST UNITED AC 2015; 6:245-263. [PMID: 26543505 DOI: 10.1111/cen3.12237] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Selective neuron loss in discrete brain regions is a hallmark of various neurodegenerative disorders, although the mechanisms responsible for this regional vulnerability of neurons remain largely unknown. Earlier studies attributed neuron dysfunction and eventual loss during neurodegenerative diseases as exclusively cell autonomous. Although cell-intrinsic factors are one critical aspect in dictating neuron death, recent evidence also supports the involvement of other central nervous system cell types in propagating non-cell autonomous neuronal injury during neurodegenerative diseases. One such example is astrocytes, which support neuronal and synaptic function, but can also contribute to neuroinflammatory processes through robust chemokine secretion. Indeed, aberrations in astrocyte function have been shown to negatively impact neuronal integrity in several neurological diseases. The present review focuses on neuroinflammatory paradigms influenced by neuron-astrocyte cross-talk in the context of select neurodegenerative diseases.
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Affiliation(s)
- Kakulavarapu V Rama Rao
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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191
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Demetrius LA, Driver JA. Preventing Alzheimer's disease by means of natural selection. J R Soc Interface 2015; 12:20140919. [PMID: 25551134 DOI: 10.1098/rsif.2014.0919] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes.
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192
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Chiu SC, Lin YJ, Huang SY, Lien CF, Chen SP, Pang CY, Lin JH, Yang KT. The Role of Intermittent Hypoxia on the Proliferative Inhibition of Rat Cerebellar Astrocytes. PLoS One 2015; 10:e0132263. [PMID: 26172116 PMCID: PMC4501806 DOI: 10.1371/journal.pone.0132263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 06/11/2015] [Indexed: 01/28/2023] Open
Abstract
Sleep apnea syndrome, characterized by intermittent hypoxia (IH), is linked with increased oxidative stress. This study investigates the mechanisms underlying IH and the effects of IH-induced oxidative stress on cerebellar astrocytes. Rat primary cerebellar astrocytes were kept in an incubator with an oscillating O2 concentration between 20% and 5% every 30 min for 1–4 days. Although the cell loss increased with the duration, the IH incubation didn’t induce apoptosis or necrosis, but rather a G0/G1 cell cycle arrest of cerebellar astrocytes was noted. ROS accumulation was associated with cell loss during IH. PARP activation, resulting in p21 activation and cyclin D1 degradation was associated with cell cycle G0/G1 arrest of IH-treated cerebellar astrocytes. Our results suggest that IH induces cell loss by enhancing oxidative stress, PARP activation and cell cycle G0/G1 arrest in rat primary cerebellar astrocytes.
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Affiliation(s)
- Sheng-Chun Chiu
- Department of Research, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan
| | - Yu-Jou Lin
- Physiological and Anatomical Medicine, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Sung-Ying Huang
- Department of Ophthalmology, Mackay Memorial Hospital, Hsinchu, Taiwan
| | - Chih-Feng Lien
- Institute of Medical Sciences, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Shee-Ping Chen
- Tzu Chi Stem Cells Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Cheng-Yoong Pang
- Institute of Medical Sciences, School of Medicine, Tzu Chi University, Hualien, Taiwan
- Department of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Jian-Hong Lin
- PhD program in Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
| | - Kun-Ta Yang
- Physiological and Anatomical Medicine, School of Medicine, Tzu Chi University, Hualien, Taiwan
- Department of Physiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
- * E-mail:
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193
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Boccardi V, Pelini L, Ercolani S, Ruggiero C, Mecocci P. From cellular senescence to Alzheimer's disease: The role of telomere shortening. Ageing Res Rev 2015; 22:1-8. [PMID: 25896211 DOI: 10.1016/j.arr.2015.04.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 11/17/2022]
Abstract
The old age population is increasing worldwide as well as age related diseases, including neurodegenerative disorders, such as Alzheimer's disease (AD), which negatively impacts on the health care systems. Aging represents per se a risk factor for AD. Thus, the study and identification of pathways within the biology of aging represent an important end point for the development of novel and effective disease-modifying drugs to treat, delay, or prevent AD. Cellular senescence and telomere shortening represent suitable and promising targets. Several studies show that cellular senescence is tightly interconnected to aging and AD, while the role of telomere dynamic and stability in AD pathogenesis is still unclear. This review will focus on the linking mechanisms between cellular senescence, telomere shortening, and AD.
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Affiliation(s)
- Virginia Boccardi
- Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy.
| | - Luca Pelini
- Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy
| | - Sara Ercolani
- Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy
| | - Carmelinda Ruggiero
- Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy
| | - Patrizia Mecocci
- Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy
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194
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Abstract
Astrocytes regulate multiple aspects of neuronal and synaptic function from development through to adulthood. Instead of addressing each function independently, this review provides a comprehensive overview of the different ways astrocytes modulate neuronal synaptic function throughout life, with a particular focus on recent findings in each area. It includes the emerging functions of astrocytes, such as a role in synapse formation, as well as more established roles, including the uptake and recycling of neurotransmitters. This broad approach covers the many ways astrocytes and neurons constantly interact to maintain the correct functioning of the brain. It is important to consider all of these diverse functions of astrocytes when investigating how astrocyte-neuron interactions regulate synaptic behavior to appreciate the complexity of these ongoing interactions.
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Affiliation(s)
- Nicola J Allen
- Salk Institute for Biological Studies, La Jolla, California 92037;
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195
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Pei L, Mu Y, Leblanc M, Alaynick W, Barish GD, Pankratz M, Tseng TW, Kaufman S, Liddle C, Yu RT, Downes M, Pfaff SL, Auwerx J, Gage FH, Evans RM. Dependence of hippocampal function on ERRγ-regulated mitochondrial metabolism. Cell Metab 2015; 21:628-36. [PMID: 25863252 PMCID: PMC4393848 DOI: 10.1016/j.cmet.2015.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 01/16/2015] [Accepted: 02/27/2015] [Indexed: 01/08/2023]
Abstract
Neurons utilize mitochondrial oxidative phosphorylation (OxPhos) to generate energy essential for survival, function, and behavioral output. Unlike most cells that burn both fat and sugar, neurons only burn sugar. Despite its importance, how neurons meet the increased energy demands of complex behaviors such as learning and memory is poorly understood. Here we show that the estrogen-related receptor gamma (ERRγ) orchestrates the expression of a distinct neural gene network promoting mitochondrial oxidative metabolism that reflects the extraordinary neuronal dependence on glucose. ERRγ(-/-) neurons exhibit decreased metabolic capacity. Impairment of long-term potentiation (LTP) in ERRγ(-/-) hippocampal slices can be fully rescued by the mitochondrial OxPhos substrate pyruvate, functionally linking the ERRγ knockout metabolic phenotype and memory formation. Consistent with this notion, mice lacking neuronal ERRγ in cerebral cortex and hippocampus exhibit defects in spatial learning and memory. These findings implicate neuronal ERRγ in the metabolic adaptations required for memory formation.
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Affiliation(s)
- Liming Pei
- Center for Mitochondrial and Epigenomic Medicine, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Yangling Mu
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mathias Leblanc
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - William Alaynick
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Grant D Barish
- Division of Endocrinology, Metabolism, and Molecular Medicine, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Matthew Pankratz
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Tiffany W Tseng
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Samantha Kaufman
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Christopher Liddle
- Storr Liver Unit, Westmead Millennium Institute and University of Sydney, Westmead Hospital, Westmead, New South Wales 2145, Australia
| | - Ruth T Yu
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Michael Downes
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Samuel L Pfaff
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Johan Auwerx
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Fred H Gage
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Ronald M Evans
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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196
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Teschemacher AG, Gourine AV, Kasparov S. A Role for Astrocytes in Sensing the Brain Microenvironment and Neuro-Metabolic Integration. Neurochem Res 2015; 40:2386-93. [DOI: 10.1007/s11064-015-1562-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 01/27/2015] [Accepted: 02/07/2015] [Indexed: 12/22/2022]
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197
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Gao C, Zhou L, Zhu W, Wang H, Wang R, He Y, Li Z. Monocarboxylate transporter-dependent mechanism confers resistance to oxygen- and glucose-deprivation injury in astrocyte-neuron co-cultures. Neurosci Lett 2015; 594:99-104. [PMID: 25827488 DOI: 10.1016/j.neulet.2015.03.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 12/16/2022]
Abstract
Hypoxic and low-glucose stressors contribute to neuronal death in many brain diseases. Astrocytes are anatomically well-positioned to shield neurons from hypoxic injury. During hypoxia/ischemia, lactate released from astrocytes is taken up by neurons and stored for energy. This process is mediated by monocarboxylate transporters (MCTs) in the central nervous system. In the present study, we investigated the ability of astrocytes to protect neurons from oxygen- and glucose-deprivation (OGD) injury via an MCT-dependent mechanism in vitro. Primary cultures of neurons, astrocytes, and astrocytes-neurons derived from rat hippocampus were subjected to OGD, MCT inhibition with small interfering (si)RNA. Cell survival and expression of MCT4, MCT2, glial fibrillary acidic protein, and neuronal nuclear antigen were evaluated. OGD significantly increased cell death in neuronal cultures and up-regulated MCT4 expression in astrocyte cultures, but no increased cell death was observed in neuron-astrocyte co-cultures or astrocyte cultures. However, neuronal cell death in co-cultures was increased by exposure to MCT4- or MCT2-specific siRNA, and this effect was attenuated by the addition of lactate into the extracellular medium of neuronal cultures prior to OGD. These findings demonstrate that resistance to OGD injury in astrocyte-neuron co-cultures occurs via an MCT-dependent mechanism.
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Affiliation(s)
- Chen Gao
- Department of Neurosurgery, AnNing Branch Hospital, Lanzhou General Hospital, Lanzhou Command, PLA, Lanzhou, Gansu Province 730070, China
| | - Liya Zhou
- Electrophysiology Examining Room, Department of Neurology, People's Hospital of Gansu Province, Lanzhou, Gansu Province 730000, China
| | - Wenxia Zhu
- Department of Traumatology, AnNing Branch Hospital, Lanzhou General Hospital, Lanzhou Command, PLA, Lanzhou, Gansu Province 730070, China
| | - Hongyun Wang
- Department of Neurosurgery, AnNing Branch Hospital, Lanzhou General Hospital, Lanzhou Command, PLA, Lanzhou, Gansu Province 730070, China
| | - Ruijuan Wang
- Department of Neurosurgery, AnNing Branch Hospital, Lanzhou General Hospital, Lanzhou Command, PLA, Lanzhou, Gansu Province 730070, China
| | - Yunfei He
- Department of Traumatology, AnNing Branch Hospital, Lanzhou General Hospital, Lanzhou Command, PLA, Lanzhou, Gansu Province 730070, China
| | - Zhiyun Li
- Department of Neurosurgery, Lanzhou General Hospital, Lanzhou Command, PLA, South of Binhe Road, No. 333, Lanzhou, Gansu Province 730050, China.
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198
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Rossier BC, Baker ME, Studer RA. Epithelial sodium transport and its control by aldosterone: the story of our internal environment revisited. Physiol Rev 2015; 95:297-340. [PMID: 25540145 DOI: 10.1152/physrev.00011.2014] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transcription and translation require a high concentration of potassium across the entire tree of life. The conservation of a high intracellular potassium was an absolute requirement for the evolution of life on Earth. This was achieved by the interplay of P- and V-ATPases that can set up electrochemical gradients across the cell membrane, an energetically costly process requiring the synthesis of ATP by F-ATPases. In animals, the control of an extracellular compartment was achieved by the emergence of multicellular organisms able to produce tight epithelial barriers creating a stable extracellular milieu. Finally, the adaptation to a terrestrian environment was achieved by the evolution of distinct regulatory pathways allowing salt and water conservation. In this review we emphasize the critical and dual role of Na(+)-K(+)-ATPase in the control of the ionic composition of the extracellular fluid and the renin-angiotensin-aldosterone system (RAAS) in salt and water conservation in vertebrates. The action of aldosterone on transepithelial sodium transport by activation of the epithelial sodium channel (ENaC) at the apical membrane and that of Na(+)-K(+)-ATPase at the basolateral membrane may have evolved in lungfish before the emergence of tetrapods. Finally, we discuss the implication of RAAS in the origin of the present pandemia of hypertension and its associated cardiovascular diseases.
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Affiliation(s)
- Bernard C Rossier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Division of Nephrology-Hypertension, University of California San Diego, La Jolla, California; and Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Michael E Baker
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Division of Nephrology-Hypertension, University of California San Diego, La Jolla, California; and Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Romain A Studer
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Division of Nephrology-Hypertension, University of California San Diego, La Jolla, California; and Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, United Kingdom
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199
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Petit JM, Burlet-Godinot S, Magistretti PJ, Allaman I. Glycogen metabolism and the homeostatic regulation of sleep. Metab Brain Dis 2015; 30:263-79. [PMID: 25399336 PMCID: PMC4544655 DOI: 10.1007/s11011-014-9629-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/04/2014] [Indexed: 12/19/2022]
Abstract
In 1995 Benington and Heller formulated an energy hypothesis of sleep centered on a key role of glycogen. It was postulated that a major function of sleep is to replenish glycogen stores in the brain that have been depleted during wakefulness which is associated to an increased energy demand. Astrocytic glycogen depletion participates to an increase of extracellular adenosine release which influences sleep homeostasis. Here, we will review some evidence obtained by studies addressing the question of a key role played by glycogen metabolism in sleep regulation as proposed by this hypothesis or by an alternative hypothesis named "glycogenetic" hypothesis as well as the importance of the confounding effect of glucocorticoïds. Even though actual collected data argue in favor of a role of sleep in brain energy balance-homeostasis, they do not support a critical and direct involvement of glycogen metabolism on sleep regulation. For instance, glycogen levels during the sleep-wake cycle are driven by different physiological signals and therefore appear more as a marker-integrator of brain energy status than a direct regulator of sleep homeostasis. In support of this we provide evidence that blockade of glycogen mobilization does not induce more sleep episodes during the active period while locomotor activity is reduced. These observations do not invalidate the energy hypothesis of sleep but indicate that underlying cellular mechanisms are more complex than postulated by Benington and Heller.
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Affiliation(s)
- Jean-Marie Petit
- Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015, Switzerland,
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200
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Geng X, Sy CA, Kwiecien TD, Ji X, Peng C, Rastogi R, Cai L, Du H, Brogan D, Singh S, Rafols JA, Ding Y. Reduced cerebral monocarboxylate transporters and lactate levels by ethanol and normobaric oxygen therapy in severe transient and permanent ischemic stroke. Brain Res 2015; 1603:65-75. [PMID: 25641040 DOI: 10.1016/j.brainres.2015.01.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 01/04/2023]
Abstract
OBJECTIVES Neuroprotective benefits of ethanol (EtOH) and normobaric oxygenation (NBO) were previously demonstrated in transient and permanent ischemic stroke. Here we sought to identify whether the enhanced lactic acidosis and increased expression of monocarboxylate transporters (MCTs) observed after stroke might be attenuated by single and/or combined EtOH and NBO therapies. METHODS Sprague-Dawley rats (n=96) were subjected to right middle cerebral artery occlusion (MCAO) for 2 or 4h (transient ischemia), or 28 h (permanent ischemia) followed by 3, 24h, or no reperfusion. Rats received: (1) either an intraperitoneal injection of saline (sham treatment), one dose of EtOH (1.5 g/kg), two doses of EtOH (1.5 g/kg at 2h of MCAO, followed by 1.0 g/kg 2h after 1st dose), or (2) EtOH+95% NBO (at 2h of MCAO for 6h in permanent ischemia). Lactate levels were detected at 3 and 24h of reperfusion. Gene and protein expressions of MCT-1, -2, -4 were assessed by real-time PCR and western blotting. RESULTS A dose-dependent EtOH neuroprotection was found in transient ischemia. Following transient ischemia, a single dose of EtOH (in 2h-MCAO) or a double dose (in 4h-MCAO), significantly attenuated lactate levels, as well as the mRNAs and protein expressions of MCT-1, MCT-2, and MCT-4. However, while two doses of EtOH alone was ineffective in permanent stroke, the combined therapy (EtOH+95% NBO) resulted in a more significant attenuation in all the above levels and expressions. CONCLUSIONS Our study demonstrates that acute EtOH administration attenuated lactic acidosis in transient or permanent ischemic stroke. This EtOH-induced beneficial effect was potentiated by NBO therapy in permanent ischemia. Because both EtOH and NBO are readily available, inexpensive and easy to administer, their combination could be implemented in the clinics shortly after stroke.
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Affiliation(s)
- Xiaokun Geng
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Christopher A Sy
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Timothy D Kwiecien
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Xunming Ji
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurosurgery, Xuanwu Hospital, China-America Institute of Neuroscience, Luhe Hospital Capital Medical University, Beijing 100053, China.
| | - Changya Peng
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Radhika Rastogi
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Lipeng Cai
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Huishan Du
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China
| | - David Brogan
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Sunpreet Singh
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Jose A Rafols
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Yuchuan Ding
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA.
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