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Dienel GA, Schousboe A, McKenna MC, Rothman DL. A tribute to Leif Hertz: The historical context of his pioneering studies of the roles of astrocytes in brain energy metabolism, neurotransmission, cognitive functions, and pharmacology identifies important, unresolved topics for future studies. J Neurochem 2024; 168:461-495. [PMID: 36928655 DOI: 10.1111/jnc.15812] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023]
Abstract
Leif Hertz, M.D., D.Sc. (honōris causā) (1930-2018), was one of the original and noteworthy participants in the International Conference on Brain Energy Metabolism (ICBEM) series since its inception in 1993. The biennial ICBEM conferences are organized by neuroscientists interested in energetics and metabolism underlying neural functions; they have had a high impact on conceptual and experimental advances in these fields and on promoting collaborative interactions among neuroscientists. Leif made major contributions to ICBEM discussions and understanding of metabolic and signaling characteristics of astrocytes and their roles in brain function. His studies ranged from uptake of K+ from extracellular fluid and its stimulation of astrocytic respiration, identification, and regulation of enzymes specifically or preferentially expressed in astrocytes in the glutamate-glutamine cycle of excitatory neurotransmission, a requirement for astrocytic glycogenolysis for fueling K+ uptake, involvement of glycogen in memory consolidation in the chick, and pharmacology of astrocytes. This tribute to Leif Hertz highlights his major discoveries, the high impact of his work on astrocyte-neuron interactions, and his unparalleled influence on understanding the cellular basis of brain energy metabolism. His work over six decades has helped integrate the roles of astrocytes into neurotransmission where oxidative and glycogenolytic metabolism during neurotransmitter glutamate turnover are key aspects of astrocytic energetics. Leif recognized that brain astrocytic metabolism is greatly underestimated unless the volume fraction of astrocytes is taken into account. Adjustment for pathway rates expressed per gram tissue for volume fraction indicates that astrocytes have much higher oxidative rates than neurons and astrocytic glycogen concentrations and glycogenolytic rates during sensory stimulation in vivo are similar to those in resting and exercising muscle, respectively. These novel insights are typical of Leif's astute contributions to the energy metabolism field, and his publications have identified unresolved topics that provide the neuroscience community with challenges and opportunities for future research.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, 72205, USA
- Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, 87131, USA
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, 21201, USA
| | - Douglas L Rothman
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, Connecticut, 06520, USA
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Hao M, Qin Y, Li Y, Tang Y, Ma Z, Tan J, Jin L, Wang F, Gong X. Metabolome subtyping reveals multi-omics characteristics and biological heterogeneity in major psychiatric disorders. Psychiatry Res 2023; 330:115605. [PMID: 38006718 DOI: 10.1016/j.psychres.2023.115605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 11/02/2023] [Accepted: 11/10/2023] [Indexed: 11/27/2023]
Abstract
Growing evidence suggests that major psychiatric disorders (MPDs) share common etiologies and pathological processes. However, the diagnosis is currently based on descriptive symptoms, which ignores the underlying pathogenesis and hinders the development of clinical treatments. This highlights the urgency of characterizing molecular biomarkers and establishing objective diagnoses of MPDs. Here, we collected untargeted metabolomics, proteomics and DNA methylation data of 327 patients with MPDs, 131 individuals with genetic high risk and 146 healthy controls to explore the multi-omics characteristics of MPDs. First, differential metabolites (DMs) were identified and we classified MPD patients into 3 subtypes based on DMs. The subtypes showed distinct metabolomics, proteomics and DNA methylation signatures. Specifically, one subtype showed dysregulation of complement and coagulation proteins, while the DNA methylation showed abnormalities in chemical synapses and autophagy. Integrative analysis in metabolic pathways identified the important roles of the citrate cycle, sphingolipid metabolism and amino acid metabolism. Finally, we constructed prediction models based on the metabolites and proteomics that successfully captured the risks of MPD patients. Our study established molecular subtypes of MPDs and elucidated their biological heterogeneity through a multi-omics investigation. These results facilitate the understanding of pathological mechanisms and promote the diagnosis and prevention of MPDs.
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Affiliation(s)
- Meng Hao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China; Zhangjiang Fudan International Innovation Center, Fudan Zhangjiang Institute, Obstetrics and Gynecology Hospital, Human Phenome Institute, Fudan University, China
| | - Yue Qin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China; Zhangjiang Fudan International Innovation Center, Fudan Zhangjiang Institute, Obstetrics and Gynecology Hospital, Human Phenome Institute, Fudan University, China
| | - Yi Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China; Zhangjiang Fudan International Innovation Center, Fudan Zhangjiang Institute, Obstetrics and Gynecology Hospital, Human Phenome Institute, Fudan University, China; International Human Phenome Institutes, Shanghai, China
| | - Yanqing Tang
- Department of Psychiatry, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Zehan Ma
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Jingze Tan
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Li Jin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China; Zhangjiang Fudan International Innovation Center, Fudan Zhangjiang Institute, Obstetrics and Gynecology Hospital, Human Phenome Institute, Fudan University, China; International Human Phenome Institutes, Shanghai, China
| | - Fei Wang
- Early Intervention Unit, Department of Psychiatry, Affiliated Nanjing Brain Hospital, Nanjing Medical University, Nanjing, China; Functional Brain Imaging Institute of Nanjing Medical University, Nanjing, China.
| | - Xiaohong Gong
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China.
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Hopper AJ, Beswick‐Jones H, Brown AM. Resilience of compound action potential peaks to high-frequency firing in the mouse optic nerve. Physiol Rep 2023; 11:e15606. [PMID: 36807847 PMCID: PMC9937793 DOI: 10.14814/phy2.15606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/16/2023] [Accepted: 01/23/2023] [Indexed: 02/19/2023] Open
Abstract
Action potential conduction in axons triggers trans-membrane ion movements, where Na+ enters and K+ leaves axons, leading to disruptions in resting trans-membrane ion gradients that must be restored for optimal axon conduction, an energy dependent process. The higher the stimulus frequency, the greater the ion movements and the resulting energy demand. In the mouse optic nerve (MON), the stimulus evoked compound action potential (CAP) displays a triple peaked profile, consistent with subpopulations of axons classified by size producing the distinct peaks. The three CAP peaks show differential sensitivity to high-frequency firing, with the large axons, which contribute to the 1st peak, more resilient than the small axons, which produce the 3rd peak. Modeling studies predict frequency dependent intra-axonal Na+ accumulation at the nodes of Ranvier, sufficient to attenuate the triple peaked CAP. Short bursts of high-frequency stimulus evoke transient elevations in interstitial K+ ([K+ ]o ), which peak at about 50 Hz. However, powerful astrocytic buffering limits the [K+ ]o increase to levels insufficient to cause CAP attenuation. A post-stimulus [K+ ]o undershoot below baseline coincides with a transient increase in the amplitudes of all three CAP peaks. The volume specific scaling relating energy expenditure to increasing axon size dictates that large axons are more resilient to high-frequency firing than small axons.
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Affiliation(s)
- Amy J. Hopper
- School of Life SciencesUniversity of NottinghamNottinghamUK
| | | | - Angus M. Brown
- School of Life SciencesUniversity of NottinghamNottinghamUK,Department of Neurology, School of MedicineUniversity of WashingtonSeattleWashingtonUSA
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Nartsissov YR. Application of a multicomponent model of convectional reaction-diffusion to description of glucose gradients in a neurovascular unit. Front Physiol 2022; 13:843473. [PMID: 36072843 PMCID: PMC9444140 DOI: 10.3389/fphys.2022.843473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Accepted: 07/18/2022] [Indexed: 11/16/2022] Open
Abstract
A supply of glucose to a nervous tissue is fulfilled by a cerebrovascular network, and further diffusion is known to occur at both an arteriolar and a microvascular level. Despite a direct relation, a blood flow dynamic and reaction-diffusion of metabolites are usually considered separately in the mathematical models. In the present study they are coupled in a multiphysical approach which allows to evaluate the effects of capillary blood flow changes on near-vessels nutrient concentration gradients evidently. Cerebral blood flow (CBF) was described by the non-steady-state Navier-Stokes equations for a non-Newtonian fluid whose constitutive law is given by the Carreau model. A three-level organization of blood–brain barrier (BBB) is modelled by the flux dysconnectivity functions including densities and kinetic properties of glucose transporters. The velocity of a fluid flow in brain extracellular space (ECS) was estimated using Darcy’s law. The equations of reaction-diffusion with convection based on a generated flow field for continues and porous media were used to describe spatial-time gradients of glucose in the capillary lumen and brain parenchyma of a neurovascular unit (NVU), respectively. Changes in CBF were directly simulated using smoothing step-like functions altering the difference of intracapillary pressure in time. The changes of CBF cover both the decrease (on 70%) and the increase (on 50%) in a capillary flow velocity. Analyzing the dynamics of glucose gradients, it was shown that a rapid decrease of a capillary blood flow yields an enhanced level of glucose in a near-capillary nervous tissue if the contacts between astrocytes end-feet are not tight. Under the increased CBF velocities the amplitude of glucose concentration gradients is always enhanced. The introduced approach can be used for estimation of blood flow changes influence not only on glucose but also on other nutrients concentration gradients and for the modelling of distributions of their concentrations near blood vessels in other tissues as well.
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Eprintsev AT, Bondareva IR, Selivanova NV. [Expression levels and activity of rat liver lactate dehydrogenase isoenzymes in alloxan diabetes]. BIOMEDITSINSKAIA KHIMIIA 2022; 68:32-38. [PMID: 35221294 DOI: 10.18097/pbmc20226801032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A significant decrease in the activity of lactate dehydrogenase (LDH, EC 1.1.1.27) in liver cells of rats with alloxan diabetes was found due to a decrease in the expression of the corresponding genes. The decrease in the activity of the enzyme under study in experimental type I diabetes was associated with inactivation of the cytoplasmic isoform of LDH. It was found that the level of ldha and ldhb gene transcripts in the liver of healthy rats was higher than in animals with alloxan diabetes. The ldha gene expression demonstrated almost 9-fold decrease, while a decrease in the ldhb gene expression was less pronounced (just 1.25-fold). Probably, the decrease in the rate of functioning of the enzyme under study is associated with a decrease in the intensity of glucose uptake by cells, which leads to inhibition of glycolysis and intensification of all stages of gluconeogenesis, particularly, reversed glycolysis reactions. Thus, the data obtained by us indicate an important role of LDH in the adaptive response of cellular metabolism in the development of type I diabetes mellitus.
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Mahan VL. Effects of lactate and carbon monoxide interactions on neuroprotection and neuropreservation. Med Gas Res 2021; 11:158-173. [PMID: 34213499 PMCID: PMC8374456 DOI: 10.4103/2045-9912.318862] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/21/2020] [Accepted: 10/23/2020] [Indexed: 11/04/2022] Open
Abstract
Lactate, historically considered a waste product of anerobic metabolism, is a metabolite in whole-body metabolism needed for normal central nervous system (CNS) functions and a potent signaling molecule and hormone in the CNS. Neuronal activity signals normally induce its formation primarily in astrocytes and production is dependent on anerobic and aerobic metabolisms. Functions are dependent on normal dynamic, expansive, and evolving CNS functions. Levels can change under normal physiologic conditions and with CNS pathology. A readily combusted fuel that is sshuttled throughout the body, lactate is used as an energy source and is needed for CNS hemostasis, plasticity, memory, and excitability. Diffusion beyond the neuron active zone impacts activity of neurons and astrocytes in other areas of the brain. Barriergenesis, function of the blood-brain barrier, and buffering between oxidative metabolism and glycolysis and brain metabolism are affected by lactate. Important to neuroprotection, presence or absence is associated with L-lactate and heme oxygenase/carbon monoxide (a gasotransmitter) neuroprotective systems. Effects of carbon monoxide on L-lactate affect neuroprotection - interactions of the gasotransmitter with L-lactate are important to CNS stability, which will be reviewed in this article.
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Affiliation(s)
- Vicki L. Mahan
- Department of Surgery and Pediatrics, Drexel University College of Medicine, Philadelphia, PA, USA
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Metabolomics profiling of plasma, urine and saliva after short term training in young professional football players in Saudi Arabia. Sci Rep 2020; 10:19759. [PMID: 33184375 PMCID: PMC7665217 DOI: 10.1038/s41598-020-75755-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/19/2020] [Indexed: 02/06/2023] Open
Abstract
Metabolomics profiling was carried out to observe the effect of short-term intensive physical activity on the metabolome of young Saudi professional football players. Urine, plasma and saliva were collected on 2 days pre- and post-training. An Orbitrap Exactive mass spectrometer was used to analyze the samples. A reversed-phase (RP) column was used for the analysis of non-polar plasma metabolites, and a ZIC-pHILIC column was used for the analysis of plasma, saliva and urine. mzMine was used to extract the data, and the results were modelled using Simca-P 14.1 software. There was no marked variation in the metabolite profiles between pre day 1 and 2 or between post day 1 and 2 according to principal components analysis (PCA). When orthogonal partial least squares (OPLSDA) modelling was also used, and then models could be fitted based on a total number of metabolites of 75, 16 and 32 for urine, plasma and saliva using hydrophilic interaction chromatography (HILIC) and 6 for analysis of plasma with reversed-phase (RP) chromatography respectively. The present study concludes that acylcarnitine may increase post-exercise in football players suggesting that they may burn fat rather than glucose. The levels of carnitine metabolites in plasma post-exercise could provide an important indicator of fitness.
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Coco M, Buscemi A, Pennisi E, Cavallari P, Papotto G, Papotto GMF, Perciavalle V, Di Corrado D, Perciavalle V. Postural Control and Stress Exposure in Young Men: Changes in Cortisol Awakening Response and Blood Lactate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:7222. [DOI: https:/doi.org/10.3390/ijerph17197222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
Background: It has recently been noticed that the quantity of stress affects postural stability in young women. The study was conducted with the goal of investigating whether increased stress may damagingly effect posture control in 90 young men (71 right-handed and 19 left-handed) while maintaining an upright bipedal posture, while keeping their eyes open or closed. Perceived Stress Scale (PSS) was administered and changes in free cortisol levels were monitored (Cortisol Awakening Response, CAR) in order to evaluate the amount of stress present during awakening, while the Profile of Mood States (POMS) was used to estimate distress on the whole. Posture control was evaluated with the use of a force platform, which, while computing a confidence ellipse area of 95%, was engaged by the Center of Pressure through five stability stations and was sustained for a minimum of 52 s, with and without visual input. Another goal of the experiment was to find out whether or not cortisol increases in CAR were linked with rises of blood lactate levels. Results: CAR, PSS and POMS were found to be extensively related. Furthermore, it has been observed that increases in salivary cortisol in CAR are associated with small but significant increases in blood lactate levels. As expected, stress levels did affect postural stability. Conclusions: The results of the present study confirm that the level of stress can influence postural stability, and that this influence is principally obvious when visual information is not used in postural control.
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Coco M, Buscemi A, Pennisi E, Cavallari P, Papotto G, Papotto GMF, Perciavalle V, Di Corrado D, Perciavalle V. Postural Control and Stress Exposure in Young Men: Changes in Cortisol Awakening Response and Blood Lactate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E7222. [PMID: 33023176 PMCID: PMC7579131 DOI: 10.3390/ijerph17197222] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/09/2020] [Accepted: 09/30/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND It has recently been noticed that the quantity of stress affects postural stability in young women. The study was conducted with the goal of investigating whether increased stress may damagingly effect posture control in 90 young men (71 right-handed and 19 left-handed) while maintaining an upright bipedal posture, while keeping their eyes open or closed. Perceived Stress Scale (PSS) was administered and changes in free cortisol levels were monitored (Cortisol Awakening Response, CAR) in order to evaluate the amount of stress present during awakening, while the Profile of Mood States (POMS) was used to estimate distress on the whole. Posture control was evaluated with the use of a force platform, which, while computing a confidence ellipse area of 95%, was engaged by the Center of Pressure through five stability stations and was sustained for a minimum of 52 s, with and without visual input. Another goal of the experiment was to find out whether or not cortisol increases in CAR were linked with rises of blood lactate levels. RESULTS CAR, PSS and POMS were found to be extensively related. Furthermore, it has been observed that increases in salivary cortisol in CAR are associated with small but significant increases in blood lactate levels. As expected, stress levels did affect postural stability. CONCLUSIONS The results of the present study confirm that the level of stress can influence postural stability, and that this influence is principally obvious when visual information is not used in postural control.
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Affiliation(s)
- Marinella Coco
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
- Motor Activity Research Center (CRAM), University of Catania, 95123 Catania, Italy
| | - Andrea Buscemi
- Horus Social Cooperative, Department of Research, 97100 Ragusa, Italy;
- Department of Research, Italian Center Studies of Osteopathy, 95100 Catania, Italy
| | - Emanuele Pennisi
- Department of Educational Sciences, University of Catania, 95100 Catania, Italy; (E.P.); (V.P.)
| | - Paolo Cavallari
- Department of Pathophysiology and Transplantation, Human Physiology Section, University of Milan, 20122 Milan, Italy;
| | - Giacomo Papotto
- University Hospital “Policlinico G. Rodolico-San Marco”, University of Catania, 95123 Catania, Italy;
| | | | - Vincenzo Perciavalle
- Department of Human and Social Sciences, School of Sport Sciences, Kore University, 94100 Enna, Italy; (D.D.C.); (V.P.)
| | - Donatella Di Corrado
- Department of Human and Social Sciences, School of Sport Sciences, Kore University, 94100 Enna, Italy; (D.D.C.); (V.P.)
| | - Valentina Perciavalle
- Department of Educational Sciences, University of Catania, 95100 Catania, Italy; (E.P.); (V.P.)
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Janicot R, Stafstrom CE, Shao LR. 2-Deoxyglucose terminates pilocarpine-induced status epilepticus in neonatal rats. Epilepsia 2020; 61:1528-1537. [PMID: 32558935 DOI: 10.1111/epi.16583] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/27/2020] [Accepted: 05/27/2020] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Neonatal status epilepticus (SE) is a life-threatening medical emergency. Unfortunately, up to 50% of neonates with SE are resistant to current antiseizure drugs, highlighting the need for better treatments. This study aims to explore a novel metabolic approach as a potential alternative treatment to control neonatal SE, using the glycolytic inhibitor 2-deoxyglucose (2-DG). METHODS SE was induced by pilocarpine (300 mg/kg, intraperitoneally [ip]) in neonatal Sprague Dawley rats (postnatal day 10 [P10]-P17) and was monitored by video-electroencephalography (V-EEG). After 30 minutes of SE, 2-DG or one of two conventional antiseizure drugs with different mechanisms of action, phenobarbital or levetiracetam, was administrated ip, and V-EEG recording was continued for ~60 additional minutes. The time to seizure cessation after drug injection, EEG scores, and power spectra before and after drug or saline treatment were used to assess drug effects. RESULTS Once SE became sustained, administration of 2-DG (50, 100, or 500 mg/kg, ip) consistently stopped behavioral and electrographic seizures within 10-15 minutes; lower doses took longer (25-30 minutes) to stop SE, demonstrating a dose-dependent effect. Administration of phenobarbital (30 mg/kg, ip) or levetiracetam (100 mg/kg, ip) also stopped SE within 10-15 minutes in neonatal rats. SIGNIFICANCE Our results suggest that the glycolysis inhibitor 2-DG acts quickly to reduce neuronal hyperexcitability and effectively suppress ongoing seizure activity, which may provide translational value in the treatment of neonatal SE.
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Affiliation(s)
- Remi Janicot
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Carl E Stafstrom
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Li-Rong Shao
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Patsatzis DG, Tingas EA, Goussis DA, Sarathy SM. Computational singular perturbation analysis of brain lactate metabolism. PLoS One 2019; 14:e0226094. [PMID: 31846455 PMCID: PMC6917278 DOI: 10.1371/journal.pone.0226094] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 11/19/2019] [Indexed: 01/09/2023] Open
Abstract
Lactate in the brain is considered an important fuel and signalling molecule for neuronal activity, especially during neuronal activation. Whether lactate is shuttled from astrocytes to neurons or from neurons to astrocytes leads to the contradictory Astrocyte to Neuron Lactate Shuttle (ANLS) or Neuron to Astrocyte Lactate Shuttle (NALS) hypotheses, both of which are supported by extensive, but indirect, experimental evidence. This work explores the conditions favouring development of ANLS or NALS phenomenon on the basis of a model that can simulate both by employing the two parameter sets proposed by Simpson et al. (J Cereb. Blood Flow Metab., 27:1766, 2007) and Mangia et al. (J of Neurochemistry, 109:55, 2009). As most mathematical models governing brain metabolism processes, this model is multi-scale in character due to the wide range of time scales characterizing its dynamics. Therefore, we utilize the Computational Singular Perturbation (CSP) algorithm, which has been used extensively in multi-scale systems of reactive flows and biological systems, to identify components of the system that (i) generate the characteristic time scale and the fast/slow dynamics, (ii) participate to the expressions that approximate the surfaces of equilibria that develop in phase space and (iii) control the evolution of the process within the established surfaces of equilibria. It is shown that a decisive factor on whether the ANLS or NALS configuration will develop during neuronal activation is whether the lactate transport between astrocytes and interstitium contributes to the fast dynamics or not. When it does, lactate is mainly generated in astrocytes and the ANLS hypothesis is realised, while when it doesn't, lactate is mainly generated in neurons and the NALS hypothesis is realised. This scenario was tested in exercise conditions.
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Affiliation(s)
- Dimitris G. Patsatzis
- King Abdullah University of Science and Technology (KAUST), Clean Combustion Research Center (CCRC), Thuwal, Saudi Arabia
- Department of Mechanics, School of Applied Mathematics and Physical Sciences, National Technical University of Athens (NTUA), Athens, Greece
| | - Efstathios-Al. Tingas
- King Abdullah University of Science and Technology (KAUST), Clean Combustion Research Center (CCRC), Thuwal, Saudi Arabia
- Perth College, University of the Highlands and Islands, Crieff Rd, Perth PH1 2NX, United Kingdom
| | - Dimitris A. Goussis
- Department of Mechanical Engineering, Khalifa University of Science, Technology and Research (KUSTAR), Abu Dhabi, United Arab Emirates
| | - S. Mani Sarathy
- King Abdullah University of Science and Technology (KAUST), Clean Combustion Research Center (CCRC), Thuwal, Saudi Arabia
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Bordone MP, Salman MM, Titus HE, Amini E, Andersen JV, Chakraborti B, Diuba AV, Dubouskaya TG, Ehrke E, Espindola de Freitas A, Braga de Freitas G, Gonçalves RA, Gupta D, Gupta R, Ha SR, Hemming IA, Jaggar M, Jakobsen E, Kumari P, Lakkappa N, Marsh APL, Mitlöhner J, Ogawa Y, Paidi RK, Ribeiro FC, Salamian A, Saleem S, Sharma S, Silva JM, Singh S, Sulakhiya K, Tefera TW, Vafadari B, Yadav A, Yamazaki R, Seidenbecher CI. The energetic brain - A review from students to students. J Neurochem 2019; 151:139-165. [PMID: 31318452 DOI: 10.1111/jnc.14829] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/03/2019] [Accepted: 07/08/2019] [Indexed: 12/12/2022]
Abstract
The past 20 years have resulted in unprecedented progress in understanding brain energy metabolism and its role in health and disease. In this review, which was initiated at the 14th International Society for Neurochemistry Advanced School, we address the basic concepts of brain energy metabolism and approach the question of why the brain has high energy expenditure. Our review illustrates that the vertebrate brain has a high need for energy because of the high number of neurons and the need to maintain a delicate interplay between energy metabolism, neurotransmission, and plasticity. Disturbances to the energetic balance, to mitochondria quality control or to glia-neuron metabolic interaction may lead to brain circuit malfunction or even severe disorders of the CNS. We cover neuronal energy consumption in neural transmission and basic ('housekeeping') cellular processes. Additionally, we describe the most common (glucose) and alternative sources of energy namely glutamate, lactate, ketone bodies, and medium chain fatty acids. We discuss the multifaceted role of non-neuronal cells in the transport of energy substrates from circulation (pericytes and astrocytes) and in the supply (astrocytes and microglia) and usage of different energy fuels. Finally, we address pathological consequences of disrupted energy homeostasis in the CNS.
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Affiliation(s)
- Melina Paula Bordone
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mootaz M Salman
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Haley E Titus
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Elham Amini
- Department of Medicine, University Kebangsaan Malaysia Medical Centre (HUKM), Cheras, Kuala Lumpur, Malaysia
| | - Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Artem V Diuba
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Tatsiana G Dubouskaya
- Institute of Biophysics and Cell Engineering, National Academy of Sciences of Belarus, Minsk, Belarus
| | - Eric Ehrke
- Centre for Biomolecular Interactions, University of Bremen, Bremen, Germany
| | - Andiara Espindola de Freitas
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, California, USA
| | | | | | | | - Richa Gupta
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Sharon R Ha
- Baylor College of Medicine, Houston, Texas, USA
| | - Isabel A Hemming
- Brain Growth and Disease Laboratory, The Harry Perkins Institute of Medical Research, Nedlands, Western Australia, Australia.,School of Medicine and Pharmacology, The University of Western Australia, Crawley, Australia
| | - Minal Jaggar
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Punita Kumari
- Defense Institute of Physiology and allied sciences, Defense Research and Development Organization, Timarpur, Delhi, India
| | - Navya Lakkappa
- Department of Pharmacology, JSS college of Pharmacy, Ooty, India
| | - Ashley P L Marsh
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Jessica Mitlöhner
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany
| | - Yuki Ogawa
- The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | | | | | - Ahmad Salamian
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Suraiya Saleem
- CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Sorabh Sharma
- Department of Pharmacy, Birla Institute of Technology and Science, Pilani, Rajasthan, India
| | - Joana M Silva
- Life and Health Sciences Research Institute (ICVS), Medical School, University of Minho, Braga, Portugal
| | - Shripriya Singh
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Kunjbihari Sulakhiya
- Department of Pharmacy, Indira Gandhi National Tribal University, Amarkantak, India
| | - Tesfaye Wolde Tefera
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Behnam Vafadari
- Institute of environmental medicine, UNIKA-T, Technical University of Munich, Munich, Germany
| | - Anuradha Yadav
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Reiji Yamazaki
- Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.,Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
| | - Constanze I Seidenbecher
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
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13
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Bellesi M, de Vivo L, Koebe S, Tononi G, Cirelli C. Sleep and Wake Affect Glycogen Content and Turnover at Perisynaptic Astrocytic Processes. Front Cell Neurosci 2018; 12:308. [PMID: 30254569 PMCID: PMC6141665 DOI: 10.3389/fncel.2018.00308] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/23/2018] [Indexed: 12/26/2022] Open
Abstract
Astrocytic glycogen represents the only form of glucose storage in the brain, and one of the outcomes of its breakdown is the production of lactate that can be used by neurons as an alternative energetic substrate. Since brain metabolism is higher in wake than in sleep, it was hypothesized that glycogen stores are depleted during wake and replenished during sleep. Furthermore, it was proposed that glycogen depletion leads to the progressive increase in adenosine levels during wake, providing a homeostatic signal that reflects the buildup of sleep pressure. However, previous studies that measured glycogen dynamics across the sleep/wake cycle obtained inconsistent results, and only measured glycogen in whole tissue. Since most energy in the brain is used to sustain synaptic activity, here we employed tridimensional electron microscopy to quantify glycogen content in the astrocytic processes surrounding the synapse. We studied axon-spine synapses in the frontal cortex of young mice after ~7 h of sleep, 7–8 h of spontaneous or forced wake, or 4.5 days of sleep restriction. Relative to sleep, all wake conditions increased the number of glycogen granules around the synapses to a similar extent. However, progressively longer periods of wake were associated with progressively smaller glycogen granules, suggesting increased turnover. Despite the increased number of granules, in all wake conditions the estimated amount of glucose within the granules was lower than in sleep, indicating that sleep may favor glucose storage. Finally, chronic sleep restriction moved glycogen granules closer to the synaptic cleft. Thus, both short and long wake lead to increased glycogen turnover around cortical synapses, whereas sleep promotes glycogen accumulation.
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Affiliation(s)
- Michele Bellesi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States.,Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Luisa de Vivo
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States
| | - Samuel Koebe
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States
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14
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Abstract
PURPOSE OF REVIEW The goal of the present paper is to review current literature supporting the occurrence of fundamental changes in brain energy metabolism during the transition from wakefulness to sleep. RECENT FINDINGS Latest research in the field indicates that glucose utilization and the concentrations of several brain metabolites consistently change across the sleep-wake cycle. Lactate, a product of glycolysis that is involved in synaptic plasticity, has emerged as a good biomarker of brain state. Sleep-induced changes in cerebral metabolite levels result from a shift in oxidative metabolism, which alters the reliance of brain metabolism upon carbohydrates. We found wide support for the notion that brain energetics is state dependent. In particular, fatty acids and ketone bodies partly replace glucose as cerebral energy source during sleep. This mechanism plausibly accounts for increases in biosynthetic pathways and functional alterations in neuronal activity associated with sleep. A better account of brain energy metabolism during sleep might help elucidate the long mysterious restorative effects of sleep for the whole organism.
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Affiliation(s)
- Nadia Nielsen Aalling
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Allé 14, 2200, Copenhagen N, Denmark
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Allé 14, 2200, Copenhagen N, Denmark.,Center for Translational Neuromedicine, University of Rochester Medical School, Rochester, NY, 14640, USA
| | - Mauro DiNuzzo
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, Faculty of Health and Medical Sciences, University of Copenhagen, Nørre Allé 14, 2200, Copenhagen N, Denmark.
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15
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Herrera-López G, Galván EJ. Modulation of hippocampal excitability via the hydroxycarboxylic acid receptor 1. Hippocampus 2018; 28:557-567. [PMID: 29704292 DOI: 10.1002/hipo.22958] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/19/2018] [Accepted: 04/21/2018] [Indexed: 01/15/2023]
Abstract
In addition to its prominent role as an energetic substrate in the brain, lactate is emerging as a signaling molecule capable of controlling neuronal excitability. The finding that the lactate-activated receptor (hydroxycarboxylic acid receptor 1; HCA1) is widely expressed in the brain opened up the possibility that lactate exerts modulation of neuronal activity via a transmembranal receptor-linked mechanism. Here, we show that lactate causes biphasic modulation of the intrinsic excitability of CA1 pyramidal cells. In the low millimolar range, lactate or the HCA1 agonist 3,5-DHBA reduced the input resistance and membrane time constant. In addition, activation of HCA1 significantly blocked the fast inactivating sodium current and increased the delay from inactivation to a conducting state of the sodium channel. As the observed actions occurred in the presence of 4-CIN, a blocker of the neuronal monocarboxylate transporter, the possibility that lactate acted via neuronal metabolism is unlikely. Consistently, modulation of the intrinsic excitability was abolished when CA1 pyramidal cells were dialyzed with pertussis toxin, indicating the dependency of a Gαi/o -protein-coupled receptor. The activation of HCA1 appears to serve as a restraining mechanism during enhanced network activity and may function as a negative feedback for the astrocytic production of lactate.
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Affiliation(s)
- Gabriel Herrera-López
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Calzada de los Tenorios No. 235, México City 14330, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Calzada de los Tenorios No. 235, México City 14330, México
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16
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Doruyter A, Dupont P, Taljaard L, Stein DJ, Lochner C, Warwick JM. Resting regional brain metabolism in social anxiety disorder and the effect of moclobemide therapy. Metab Brain Dis 2018; 33:569-581. [PMID: 29101601 DOI: 10.1007/s11011-017-0145-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/25/2017] [Indexed: 01/26/2023]
Abstract
While there is mounting evidence of abnormal reactivity of several brain regions in social anxiety disorder, and disrupted functional connectivity between these regions at rest, relatively little is known regarding resting regional neural activity in these structures, or how such activity is affected by pharmacotherapy. Using 2-deoxy-2-(F-18)fluoro-D-glucose positron emission tomography, we compared resting regional brain metabolism between SAD and healthy control groups; and in SAD participants before and after moclobemide therapy. Voxel-based analyses were confined to a predefined search volume. A second, exploratory whole-brain analysis was conducted using a more liberal statistical threshold. Fifteen SAD participants and fifteen matched controls were included in the group comparison. A subgroup of SAD participants (n = 11) was included in the therapy effect comparison. No significant clusters were identified in the primary analysis. In the exploratory analysis, the SAD group exhibited increased metabolism in left fusiform gyrus and right temporal pole. After therapy, SAD participants exhibited reductions in regional metabolism in a medial dorsal prefrontal region and increases in right caudate, right insula and left postcentral gyrus. This study adds to the limited existing work on resting regional brain activity in SAD and the effects of therapy. The negative results of our primary analysis suggest that resting regional activity differences in the disorder, and moclobemide effects on regional metabolism, if present, are small. While the outcomes of our secondary analysis should be interpreted with caution, they may contribute to formulating future hypotheses or in pooled analyses.
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Affiliation(s)
- Alex Doruyter
- Division of Nuclear Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
| | - Patrick Dupont
- Laboratory of Cognitive Neurology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Lian Taljaard
- MRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Dan J Stein
- MRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Christine Lochner
- MRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - James M Warwick
- Division of Nuclear Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
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17
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Geometries of vasculature bifurcation can affect the level of trophic damage during formation of a brain ischemic lesion. Biochem Soc Trans 2017; 45:1097-1103. [PMID: 28900016 DOI: 10.1042/bst20160418] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/15/2017] [Accepted: 08/08/2017] [Indexed: 01/11/2023]
Abstract
Ischemic lesion is a common cause of various diseases in humans. Brain tissue is especially sensitive to this type of damage. A common reason for the appearance of an ischemic area is a stop in blood flow in some branch of the vasculature system. Then, a decreasing concentration gradient results in a low mean level of oxygen in surrounding tissues. After that, the biochemical ischemic cascade spreads. In this review, we examine these well-known events from a new angle. It is stressed that there is essential evidence to predict the formation of an ischemic micro-area at the base of vascular bifurcation geometries. Potential applications to improve neuroprotection are also discussed.
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18
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Profilo E, Peña-Altamira LE, Corricelli M, Castegna A, Danese A, Agrimi G, Petralla S, Giannuzzi G, Porcelli V, Sbano L, Viscomi C, Massenzio F, Palmieri EM, Giorgi C, Fiermonte G, Virgili M, Palmieri L, Zeviani M, Pinton P, Monti B, Palmieri F, Lasorsa FM. Down-regulation of the mitochondrial aspartate-glutamate carrier isoform 1 AGC1 inhibits proliferation and N-acetylaspartate synthesis in Neuro2A cells. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1422-1435. [DOI: 10.1016/j.bbadis.2017.02.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 02/02/2017] [Accepted: 02/20/2017] [Indexed: 12/26/2022]
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19
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Sonnay S, Gruetter R, Duarte JMN. How Energy Metabolism Supports Cerebral Function: Insights from 13C Magnetic Resonance Studies In vivo. Front Neurosci 2017; 11:288. [PMID: 28603480 PMCID: PMC5445183 DOI: 10.3389/fnins.2017.00288] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/04/2017] [Indexed: 12/25/2022] Open
Abstract
Cerebral function is associated with exceptionally high metabolic activity, and requires continuous supply of oxygen and nutrients from the blood stream. Since the mid-twentieth century the idea that brain energy metabolism is coupled to neuronal activity has emerged, and a number of studies supported this hypothesis. Moreover, brain energy metabolism was demonstrated to be compartmentalized in neurons and astrocytes, and astrocytic glycolysis was proposed to serve the energetic demands of glutamatergic activity. Shedding light on the role of astrocytes in brain metabolism, the earlier picture of astrocytes being restricted to a scaffold-associated function in the brain is now out of date. With the development and optimization of non-invasive techniques, such as nuclear magnetic resonance spectroscopy (MRS), several groups have worked on assessing cerebral metabolism in vivo. In this context, 1H MRS has allowed the measurements of energy metabolism-related compounds, whose concentrations can vary under different brain activation states. 1H-[13C] MRS, i.e., indirect detection of signals from 13C-coupled 1H, together with infusion of 13C-enriched glucose has provided insights into the coupling between neurotransmission and glucose oxidation. Although these techniques tackle the coupling between neuronal activity and metabolism, they lack chemical specificity and fail in providing information on neuronal and glial metabolic pathways underlying those processes. Currently, the improvement of detection modalities (i.e., direct detection of 13C isotopomers), the progress in building adequate mathematical models along with the increase in magnetic field strength now available render possible detailed compartmentalized metabolic flux characterization. In particular, direct 13C MRS offers more detailed dataset acquisitions and provides information on metabolic interactions between neurons and astrocytes, and their role in supporting neurotransmission. Here, we review state-of-the-art MR methods to study brain function and metabolism in vivo, and their contribution to the current understanding of how astrocytic energy metabolism supports glutamatergic activity and cerebral function. In this context, recent data suggests that astrocytic metabolism has been underestimated. Namely, the rate of oxidative metabolism in astrocytes is about half of that in neurons, and it can increase as much as the rate of neuronal metabolism in response to sensory stimulation.
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Affiliation(s)
- Sarah Sonnay
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland.,Department of Radiology, University of LausanneLausanne, Switzerland.,Department of Radiology, University of GenevaGeneva, Switzerland
| | - João M N Duarte
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
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20
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Shao LR, Stafstrom CE. Glycolytic inhibition by 2-deoxy-d-glucose abolishes both neuronal and network bursts in an in vitro seizure model. J Neurophysiol 2017; 118:103-113. [PMID: 28404824 DOI: 10.1152/jn.00100.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/24/2017] [Accepted: 04/08/2017] [Indexed: 11/22/2022] Open
Abstract
Neuronal activity is energy demanding and coupled to cellular metabolism. In this study, we investigated the effects of glycolytic inhibition with 2-deoxy-d-glucose (2-DG) on basal membrane properties, spontaneous neuronal firing, and epileptiform network bursts in hippocampal slices. The effect of glycolytic inhibition on basal membrane properties was examined in hippocampal CA1 neurons, which are not ordinarily active spontaneously. Intracellular application of 2-DG did not significantly alter the membrane input resistance, action-potential threshold, firing pattern, or input-output relationship of these neurons compared with simultaneously recorded neighboring neurons without intracellular 2-DG. The effect of glycolytic inhibition on neuronal firing was tested in spontaneously active hippocampal neurons (CA3) when synaptic transmission was left intact or blocked with AMPA, NMDA, and GABAA receptor antagonists (DNQX, APV, and bicuculline, respectively). Under both conditions (synaptic activity intact or blocked), bath application of 2-DG (2 mM) blocked spontaneous firing in ~2/3 (67 and 71%, respectively) of CA3 pyramidal neurons. In contrast, neuronal firing of CA3 neurons persisted when 2-DG was applied intracellularly, suggesting that glycolytic inhibition of individual neurons is not sufficient to stop neuronal firing. The effects of 2-DG on epileptiform network bursts in area CA3 were tested in Mg2+-free medium containing 50 µM 4-aminopyridine. Bath application of 2-DG abolished these epileptiform bursts in a dose-dependent and all-or-none manner. Taken together, these data suggest that altered glucose metabolism profoundly affects cellular and network hyperexcitability and that glycolytic inhibition by 2-DG can effectively abrogate epileptiform activity.NEW & NOTEWORTHY Neuronal activity is highly energy demanding and coupled to cellular metabolism. In this study, we demonstrate that glycolytic inhibition with 2-deoxy-d-glucose (2-DG) effectively suppresses spontaneous neuronal firing and epileptiform bursts in hippocampal slices. These data suggest that an altered metabolic state can profoundly affect cellular and network excitability, and that the glycolytic inhibitor 2-DG may hold promise as a novel treatment of drug-resistant epilepsy.
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Affiliation(s)
- Li-Rong Shao
- Division of Pediatric Neurology, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Carl E Stafstrom
- Division of Pediatric Neurology, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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21
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DeGracia DJ. Regulation of mRNA following brain ischemia and reperfusion. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28097803 DOI: 10.1002/wrna.1415] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/11/2016] [Accepted: 12/20/2016] [Indexed: 12/31/2022]
Abstract
There is growing appreciation that mRNA regulation plays important roles in disease and injury. mRNA regulation and ribonomics occur in brain ischemia and reperfusion (I/R) following stroke and cardiac arrest and resuscitation. It was recognized over 40 years ago that translation arrest (TA) accompanies brain I/R and is now recognized as part of the intrinsic stress responses triggered in neurons. However, neuron death correlates to a prolonged TA in cells fated to undergo delayed neuronal death (DND). Dysfunction of mRNA regulatory processes in cells fated to DND prevents them from translating stress-induced mRNAs such as heat shock proteins. The morphological and biochemical studies of mRNA regulation in postischemic neurons are discussed in the context of the large variety of molecular damage induced by ischemic injury. Open issues and areas of future investigation are highlighted. A sober look at the molecular complexity of ischemia-induced neuronal injury suggests that a network framework will assist in making sense of this complexity. The ribonomic network sits between the gene network and the various protein and metabolic networks. Thus, targeting the ribonomic network may prove more effective at neuroprotection than targeting specific molecular pathways, for which all efforts have failed to the present time to stop DND in stroke and after cardiac arrest. WIREs RNA 2017, 8:e1415. doi: 10.1002/wrna.1415 For further resources related to this article, please visit the WIREs website.
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22
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Targeting Glial Mitochondrial Function for Protection from Cerebral Ischemia: Relevance, Mechanisms, and the Role of MicroRNAs. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:6032306. [PMID: 27777645 PMCID: PMC5061974 DOI: 10.1155/2016/6032306] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 08/21/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022]
Abstract
Astrocytes and microglia play crucial roles in the response to cerebral ischemia and are effective targets for stroke therapy in animal models. MicroRNAs (miRs) are important posttranscriptional regulators of gene expression that function by inhibiting the translation of select target genes. In astrocytes, miR expression patterns regulate mitochondrial function in response to oxidative stress via targeting of Bcl2 and heat shock protein 70 family members. Mitochondria play an active role in microglial activation, and miRs regulate the microglial neuroinflammatory response. As endogenous miR expression patterns can be altered with exogenous mimics and inhibitors, miR-targeted therapies represent a viable intervention to optimize glial mitochondrial function and improve clinical outcome following cerebral ischemia. In the present article, we review the role that astrocytes and microglia play in neuronal function and fate following ischemic stress, discuss the relevance of mitochondria in the glial response to injury, and present current evidence implicating miRs as critical regulators in the glial mitochondrial response to cerebral ischemia.
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23
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Kaiser LG, Hirokazu K, Fukunaga M, B.Matson G. Detection of glucose in the human brain with1HMRS at 7 Tesla. Magn Reson Med 2016; 76:1653-1660. [DOI: 10.1002/mrm.26456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/12/2016] [Accepted: 08/15/2016] [Indexed: 11/08/2022]
Affiliation(s)
| | | | - Masaki Fukunaga
- National Institute for Physiological Sciences; Okazaki Aichi Japan
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24
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Multifactorial Effects on Different Types of Brain Cells Contribute to Ammonia Toxicity. Neurochem Res 2016; 42:721-736. [PMID: 27286679 DOI: 10.1007/s11064-016-1966-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 12/12/2022]
Abstract
Effects of ammonia on astrocytes play a major role in hepatic encephalopathy, acute liver failure and other diseases caused by increased arterial ammonia concentrations (e.g., inborn errors of metabolism, drug or mushroom poisoning). There is a direct correlation between arterial ammonia concentration, brain ammonia level and disease severity. However, the pathophysiology of hyperammonemic diseases is disputed. One long recognized factor is that increased brain ammonia triggers its own detoxification by glutamine formation from glutamate. This is an astrocytic process due to the selective expression of the glutamine synthetase in astrocytes. A possible deleterious effect of the resulting increase in glutamine concentration has repeatedly been discussed and is supported by improvement of some pathologic effects by GS inhibition. However, this procedure also inhibits a large part of astrocytic energy metabolism and may prevent astrocytes from responding to pathogenic factors. A decrease of the already low glutamate concentration in astrocytes due to increased synthesis of glutamine inhibits the malate-aspartate shuttle and energy metabolism. A more recently described pathogenic factor is the resemblance between NH4+ and K+ in their effects on the Na+,K+-ATPase and the Na+,K+, 2 Cl- and water transporter NKCC1. Stimulation of the Na+,K+-ATPase driven NKCC1 in both astrocytes and endothelial cells is essential for the development of brain edema. Na+,K+-ATPase stimulation also activates production of endogenous ouabains. This leads to oxidative and nitrosative damage and sensitizes NKCC1. Administration of ouabain antagonists may accordingly have therapeutic potential in hyperammonemic diseases.
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25
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Abstract
Stroke is the second foremost cause of mortality worldwide and a major cause of long-term disability. Due to changes in lifestyle and an aging population, the incidence of stroke continues to increase and stroke mortality predicted to exceed 12 % by the year 2030. However, the development of pharmacological treatments for stroke has failed to progress much in over 20 years since the introduction of the thrombolytic drug, recombinant tissue plasminogen activator. These alarming circumstances caused many research groups to search for alternative treatments in the form of neuroprotectants. Here, we consider the potential use of phytochemicals in the treatment of stroke. Their historical use in traditional medicine and their excellent safety profile make phytochemicals attractive for the development of therapeutics in human diseases. Emerging findings suggest that some phytochemicals have the ability to target multiple pathophysiological processes involved in stroke including oxidative stress, inflammation and apoptotic cell death. Furthermore, epidemiological studies suggest that the consumption of plant sources rich in phytochemicals may reduce stroke risk, and so reinforce the possibility of developing preventative or neuroprotectant therapies for stroke. In this review, we describe results of preclinical studies that demonstrate beneficial effects of phytochemicals in experimental models relevant to stroke pathogenesis, and we consider their possible mechanisms of action.
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26
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Gibbs ME. Role of Glycogenolysis in Memory and Learning: Regulation by Noradrenaline, Serotonin and ATP. Front Integr Neurosci 2016; 9:70. [PMID: 26834586 PMCID: PMC4717441 DOI: 10.3389/fnint.2015.00070] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/17/2015] [Indexed: 01/06/2023] Open
Abstract
This paper reviews the role played by glycogen breakdown (glycogenolysis) and glycogen re-synthesis in memory processing in two different chick brain regions, (1) the hippocampus and (2) the avian equivalent of the mammalian cortex, the intermediate medial mesopallium (IMM). Memory processing is regulated by the neuromodulators noradrenaline and serotonin soon after training glycogen breakdown and re-synthesis. In day-old domestic chicks, memory formation is dependent on the breakdown of glycogen (glycogenolysis) at three specific times during the first 60 min after learning (around 2.5, 30, and 55 min). The chicks learn to discriminate in a single trial between beads of two colors and tastes. Inhibition of glycogen breakdown by the inhibitor of glycogen phosphorylase 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) given at specific times prior to the formation of long-term memory prevents memory forming. Noradrenergic stimulation of cultured chicken astrocytes by a selective β2-adrenergic (AR) agonist reduces glycogen levels and we believe that in vivo this triggers memory consolidation at the second stage of glycogenolysis. Serotonin acting at 5-HT2B receptors acts on the first stage, but not on the second. We have shown that noradrenaline, acting via post-synaptic α2-ARs, is also responsible for the synthesis of glycogen and our experiments suggest that there is a readily accessible labile pool of glycogen in astrocytes which is depleted within 10 min if glycogen synthesis is inhibited. Endogenous ATP promotion of memory consolidation at 2.5 and 30 min is also dependent on glycogen breakdown. ATP acts at P2Y1 receptors and the action of thrombin suggests that it causes the release of internal calcium ([Ca2+]i) in astrocytes. Glutamate and GABA, the primary neurotransmitters in the brain, cannot be synthesized in neurons de novo and neurons rely on astrocytic glutamate synthesis, requiring glycogenolysis.
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Affiliation(s)
- Marie E Gibbs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC, Australia
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27
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Glucose, Lactate, β-Hydroxybutyrate, Acetate, GABA, and Succinate as Substrates for Synthesis of Glutamate and GABA in the Glutamine-Glutamate/GABA Cycle. ADVANCES IN NEUROBIOLOGY 2016; 13:9-42. [PMID: 27885625 DOI: 10.1007/978-3-319-45096-4_2] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The glutamine-glutamate/GABA cycle is an astrocytic-neuronal pathway transferring precursors for transmitter glutamate and GABA from astrocytes to neurons. In addition, the cycle carries released transmitter back to astrocytes, where a minor fraction (~25 %) is degraded (requiring a similar amount of resynthesis) and the remainder returned to the neurons for reuse. The flux in the cycle is intense, amounting to the same value as neuronal glucose utilization rate or 75-80 % of total cortical glucose consumption. This glucose:glutamate ratio is reduced when high amounts of β-hydroxybutyrate are present, but β-hydroxybutyrate can at most replace 60 % of glucose during awake brain function. The cycle is initiated by α-ketoglutarate production in astrocytes and its conversion via glutamate to glutamine which is released. A crucial reaction in the cycle is metabolism of glutamine after its accumulation in neurons. In glutamatergic neurons all generated glutamate enters the mitochondria and its exit to the cytosol occurs in a process resembling the malate-aspartate shuttle and therefore requiring concomitant pyruvate metabolism. In GABAergic neurons one half enters the mitochondria, whereas the other one half is released directly from the cytosol. A revised concept is proposed for the synthesis and metabolism of vesicular and nonvesicular GABA. It includes the well-established neuronal GABA reuptake, its metabolism, and use for resynthesis of vesicular GABA. In contrast, mitochondrial glutamate is by transamination to α-ketoglutarate and subsequent retransamination to releasable glutamate essential for the transaminations occurring during metabolism of accumulated GABA and subsequent resynthesis of vesicular GABA.
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DiNuzzo M, Giove F, Maraviglia B, Mangia S. Monoaminergic Control of Cellular Glucose Utilization by Glycogenolysis in Neocortex and Hippocampus. Neurochem Res 2015; 40:2493-504. [PMID: 26168779 DOI: 10.1007/s11064-015-1656-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/23/2015] [Accepted: 06/30/2015] [Indexed: 01/01/2023]
Abstract
Brainstem nuclei are the principal sites of monoamine (MA) innervation to major forebrain structures. In the cortical grey matter, increased secretion of MA neuromodulators occurs in response to a wealth of environmental and homeostatic challenges, whose onset is associated with rapid, preparatory changes in neural activity as well as with increases in energy metabolism. Blood-borne glucose is the main substrate for energy production in the brain. Once entered the tissue, interstitial glucose is equally accessible to neurons and astrocytes, the two cell types accounting for most of cellular volume and energy metabolism in neocortex and hippocampus. Astrocytes also store substantial amounts of glycogen, but non-stimulated glycogen turnover is very small. The rate of cellular glucose utilization in the brain is largely determined by hexokinase, which under basal conditions is more than 90 % inhibited by its product glucose-6-phosphate (Glc-6-P). During rapid increases in energy demand, glycogen is a primary candidate in modulating the intracellular level of Glc-6-P, which can occur only in astrocytes. Glycogenolysis can produce Glc-6-P at a rate higher than uptake and phosphorylation of glucose. MA neurotransmitter are released extrasinaptically by brainstem neurons projecting to neocortex and hippocampus, thus activating MA receptors located on both neuronal and astrocytic plasma membrane. Importantly, MAs are glycogenolytic agents and thus they are exquisitely suitable for regulation of astrocytic Glc-6-P concentration, upstream substrate flow through hexokinase and hence cellular glucose uptake. Conforming to such mechanism, Gerald A. Dienel and Nancy F. Cruz recently suggested that activation of noradrenergic locus coeruleus might reversibly block astrocytic glucose uptake by stimulating glycogenolysis in these cells, thereby anticipating the rise in glucose need by active neurons. In this paper, we further develop the idea that the whole monoaminergic system modulates both function and metabolism of forebrain regions in a manner mediated by glycogen mobilization in astrocytes.
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Affiliation(s)
- Mauro DiNuzzo
- Magnetic Resonance for Brain Investigation Laboratory, Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Rome, Italy. .,Magnetic Resonance for Brain Investigation Laboratory, Via Ardeatina 306, 00179, Rome, Italy.
| | - Federico Giove
- Magnetic Resonance for Brain Investigation Laboratory, Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Rome, Italy.,Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
| | - Bruno Maraviglia
- Magnetic Resonance for Brain Investigation Laboratory, Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Rome, Italy.,Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Silvia Mangia
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
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Direct neuronal glucose uptake heralds activity-dependent increases in cerebral metabolism. Nat Commun 2015; 6:6807. [PMID: 25904018 PMCID: PMC4410436 DOI: 10.1038/ncomms7807] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 02/27/2015] [Indexed: 11/16/2022] Open
Abstract
Metabolically, the brain is a highly active organ that relies almost exclusively on glucose as its energy source. According to the astrocyte-to-neuron lactate shuttle hypothesis, glucose is taken up by astrocytes and converted to lactate, which is then oxidized by neurons. Here we show, using 2-photon imaging of a near-infrared 2-deoxyglucose analogue (2DG-IR), that glucose is taken up preferentially by neurons in awake behaving mice. Anesthesia suppressed neuronal 2DG-IR uptake and sensory stimulation was associated with a sharp increase in neuronal, but not astrocytic, 2DG-IR uptake. Moreover, hexokinase, which catalyze the first enzymatic steps in glycolysis, was highly enriched in neurons compared with astrocytes, in mouse as well as in human cortex. These observations suggest that brain activity and neuronal glucose metabolism are directly linked, and identifies the neuron as the principal locus of glucose uptake as visualized by functional brain imaging.
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Hertz L, Chen Y, Waagepetersen HS. Effects of ketone bodies in Alzheimer's disease in relation to neural hypometabolism, β-amyloid toxicity, and astrocyte function. J Neurochem 2015; 134:7-20. [PMID: 25832906 DOI: 10.1111/jnc.13107] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 03/22/2015] [Accepted: 03/24/2015] [Indexed: 12/11/2022]
Abstract
Diet supplementation with ketone bodies (acetoacetate and β-hydroxybuturate) or medium-length fatty acids generating ketone bodies has consistently been found to cause modest improvement of mental function in Alzheimer's patients. It was suggested that the therapeutic effect might be more pronounced if treatment was begun at a pre-clinical stage of the disease instead of well after its manifestation. The pre-clinical stage is characterized by decade-long glucose hypometabolism in brain, but ketone body metabolism is intact even initially after disease manifestation. One reason for the impaired glucose metabolism may be early destruction of the noradrenergic brain stem nucleus, locus coeruleus, which stimulates glucose metabolism, at least in astrocytes. These glial cells are essential in Alzheimer pathogenesis. The β-amyloid peptide Aβ interferes with their cholinergic innervation, which impairs synaptic function because of diminished astrocytic glutamate release. Aβ also reduces glucose metabolism and causes hyperexcitability. Ketone bodies are similarly used against seizures, but the effectively used concentrations are so high that they must interfere with glucose metabolism and de novo synthesis of neurotransmitter glutamate, reducing neuronal glutamatergic signaling. The lower ketone body concentrations used in Alzheimer's disease may owe their effect to support of energy metabolism, but might also inhibit release of gliotransmitter glutamate. Alzheimer's disease is a panglial-neuronal disorder with long-standing brain hypometabolism, aberrations in both neuronal and astrocytic glucose metabolism, inflammation, hyperexcitability, and dementia. Relatively low doses of β-hydroxybutyrate can have an ameliorating effect on cognitive function. This could be because of metabolic supplementation or inhibition of Aβ-induced release of glutamate as gliotransmitter, which is likely to reduce hyperexcitability and inflammation. The therapeutic β-hydroxybutyrate doses are too low to reduce neuronally released glutamate.
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Affiliation(s)
- Leif Hertz
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, China
| | - Ye Chen
- Henry M. Jackson Foundation, Bethesda, Maryland, USA
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Voss CM, Pajęcka K, Stridh MH, Nissen JD, Schousboe A, Waagepetersen HS. AMPK Activation Affects Glutamate Metabolism in Astrocytes. Neurochem Res 2015; 40:2431-42. [PMID: 25846006 DOI: 10.1007/s11064-015-1558-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/20/2022]
Abstract
Mammalian AMP-activated protein kinase (AMPK) functions as a metabolic switch. It is composed of 3 different subunits and its activation depends on phosphorylation of a threonine residue (Thr172) in the α-subunit. This phosphorylation can be brought about by 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) which in the cells is converted to a monophosphorylated nucleotide mimicking the effect of AMP. We show that the preparation of cultured astrocytes used for metabolic studies expresses AMPK, which could be phosphorylated by exposure of the cells to AICAR. The effect of AMPK activation on glutamate metabolism in astrocytes was studied using primary cultures of these cells from mouse cerebral cortex during incubation in media containing 2.5 mM glucose and 100 µM [U-(13)C]glutamate. The metabolism of glutamate including a detailed analysis of its metabolic pathways involving the tricarboxylic acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon skeleton into the TCA cycle was reduced. On the other hand, glutamate uptake into the astrocytes as well as its conversion to glutamine catalyzed by glutamine synthetase was not affected by AMPK activation. Interestingly, synthesis and release of citrate, which are hallmarks of astrocytic function, were affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK activation. Accordingly, the effects of AMPK activation appeared to be specific for certain key processes involved in glutamate metabolism.
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Affiliation(s)
- Caroline M Voss
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Kamilla Pajęcka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
- Department of Clinical Medicine, The Department of Endocrinology and Diabetes, University of Aarhus, 8000, Århus, Denmark
| | - Malin H Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Jakob D Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
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Weber B, Barros LF. The Astrocyte: Powerhouse and Recycling Center. Cold Spring Harb Perspect Biol 2015; 7:cshperspect.a020396. [PMID: 25680832 DOI: 10.1101/cshperspect.a020396] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Brain metabolism is characterized by fuel monodependence, high-energy expenditure, autonomy from the rest of body, local recycling, and marked division of labor between cell types. Although neurons spend most of the brain's energy on signaling, astrocytes bear the brunt of the metabolic load, controlling the composition of the interstitial fluid, supplying neurons with energy substrates and precursors for biosynthesis, and recycling neurotransmitters, oxidized scavengers, and other waste products. Outstanding questions in this field are the role of oligodendrocytes, the metabolic behavior of the different subtypes of astrocytes during development and disease, and the emerging notion that metabolism may participate directly in information processing.
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Affiliation(s)
- Bruno Weber
- University of Zürich, Institute of Pharmacology and Toxicology, 8057 Zürich, Switzerland
| | - L Felipe Barros
- Centro de Estudios Científicos, Casilla 1469, Valdivia, Chile
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Brown AM, Ransom BR. Astrocyte glycogen as an emergency fuel under conditions of glucose deprivation or intense neural activity. Metab Brain Dis 2015; 30:233-9. [PMID: 25037166 DOI: 10.1007/s11011-014-9588-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/30/2014] [Indexed: 10/24/2022]
Abstract
Energy metabolism in the brain is a complex process that is incompletely understood. Although glucose is agreed as the main energy support of the brain, the role of glucose is not clear, which has led to controversies that can be summarized as follows: the fate of glucose, once it enters the brain is unclear. It is not known the form in which glucose enters the cells (neurons and glia) within the brain, nor the degree of metabolic shuttling of glucose derived metabolites between cells, with a key limitation in our knowledge being the extent of oxidative metabolism, and how increased tissue activity alters this. Glycogen is present within the brain and is derived from glucose. Glycogen is stored in astrocytes and acts to provide short-term delivery of substrates to neural elements, although it may also contribute an important component to astrocyte metabolism. The roles played by glycogen awaits further study, but to date its most important role is in supporting neural elements during increased firing activity, where signaling molecules, proposed to be elevated interstitial K(+), indicative of elevated neural firing rates, activate glycogen phosphorylase leading to increased production of glycogen derived substrate.
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Affiliation(s)
- Angus M Brown
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG7-2UH, UK,
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Bosoi CR, Rose CF. Elevated cerebral lactate: Implications in the pathogenesis of hepatic encephalopathy. Metab Brain Dis 2014; 29:919-25. [PMID: 24916505 DOI: 10.1007/s11011-014-9573-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/28/2014] [Indexed: 01/31/2023]
Abstract
Hepatic encephalopathy (HE), a complex neuropsychiatric syndrome, is a frequent complication of liver failure/disease. Increased concentrations of lactate are commonly observed in HE patients, in the systemic circulation, but also in the brain. Traditionally, increased cerebral lactate is considered a marker of energy failure/impairment however alterations in lactate homeostasis may also lead to a rise in brain lactate and result in neuronal dysfunction. The latter may involve the development of brain edema. This review will target the significance of increased cerebral lactate in the pathogenesis of HE.
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Affiliation(s)
- Cristina R Bosoi
- Hepato-Neuro Laboratory, Centre Hospitalier de l'Université de Montréal (CRCHUM), 900, rue Saint-Denis - Tour Viger R08.422, Québec, H2X 0A9, Canada,
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DeGracia DJ, Tri Anggraini F, Taha DTM, Huang ZF. Inductive and Deductive Approaches to Acute Cell Injury. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:859341. [PMID: 27437490 PMCID: PMC4897055 DOI: 10.1155/2014/859341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/25/2014] [Indexed: 11/28/2022]
Abstract
Many clinically relevant forms of acute injury, such as stroke, traumatic brain injury, and myocardial infarction, have resisted treatments to prevent cell death following injury. The clinical failures can be linked to the currently used inductive models based on biological specifics of the injury system. Here we contrast the application of inductive and deductive models of acute cell injury. Using brain ischemia as a case study, we discuss limitations in inductive inferences, including the inability to unambiguously assign cell death causality and the lack of a systematic quantitative framework. These limitations follow from an overemphasis on qualitative molecular pathways specific to the injured system. Our recently developed nonlinear dynamical theory of cell injury provides a generic, systematic approach to cell injury in which attractor states and system parameters are used to quantitatively characterize acute injury systems. The theoretical, empirical, and therapeutic implications of shifting to a deductive framework are discussed. We illustrate how a deductive mathematical framework offers tangible advantages over qualitative inductive models for the development of therapeutics of acutely injured biological systems.
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Affiliation(s)
- Donald J. DeGracia
- Department of Physiology, Wayne State University, 4116 Scott Hall, 540 East Canfield Avenue, Detroit, MI 48201, USA
| | - Fika Tri Anggraini
- Department of Physiology, Wayne State University, 4116 Scott Hall, 540 East Canfield Avenue, Detroit, MI 48201, USA
| | | | - Zhi-Feng Huang
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
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Henriksen RE, Torsheim T, Thuen F. Loneliness, social integration and consumption of sugar-containing beverages: testing the social baseline theory. PLoS One 2014; 9:e104421. [PMID: 25105408 PMCID: PMC4126698 DOI: 10.1371/journal.pone.0104421] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/09/2014] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Social Baseline Theory (SBT) proposes that close relationships aid in metabolic resource management and that individuals without significant relationships may experience more demands on their own neural metabolic resources on a daily basis when solving problems, remaining vigilant against potential threats and regulating emotional responses. This study tests a hypothesised consequence derived from SBT: relative social isolation leads to increased levels of sugar intake. METHODS Based on cross-sectional, self-reported data from the Norwegian Mother and Child Cohort Study (N = 90 084), information on social integration and the consumption of both sugar-sweetened and artificially sweetened sodas and juices was obtained from a large number of women in early pregnancy. Multiple regression analyses were conducted to assess whether loneliness, marital status, relationship satisfaction, advice from others than partner, and cohesion at work is associated with consumption of sodas and juices. RESULTS Perceived loneliness was associated with elevated intake of all sugary beverages, while relationship satisfaction was negatively associated with all sugary beverages. Being married or cohabitating, having supportive friends, and having a sense of togetherness at work were associated with lower intake of two out of three sugar-containing beverages. These associations were significant, even after controlling for factors such as body mass index, weight related self-image, depression, physical activity, educational level, age and income. In comparison, a statistically significant relationship emerged between relationship satisfaction and artificially sweetened cola. No other predictor variables were significantly associated with any type of artificially sweetened beverage. CONCLUSIONS This study indicates that loneliness and social integration influence the level of consumption of sugary beverages. The results support the hypothesis derived from the Social Baseline Theory that relative social isolation leads to increased levels of sugar intake.
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Affiliation(s)
| | - Torbjørn Torsheim
- Faculty of Psychology, Department of Psychosocial Science, University of Bergen, Bergen, Norway
| | - Frode Thuen
- Centre for Evidence-Based Practice, Bergen University College, Bergen, Norway
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Stary CM, Giffard RG. Advances in astrocyte-targeted approaches for stroke therapy: an emerging role for mitochondria and microRNAS. Neurochem Res 2014; 40:301-7. [PMID: 24993363 DOI: 10.1007/s11064-014-1373-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/18/2014] [Accepted: 06/26/2014] [Indexed: 12/29/2022]
Abstract
Astrocytes are critical regulators of neuronal function and an effective target for stroke therapy in animal models. Identifying individual targets with the potential for simultaneous activation of multiple downstream pathways that regulate astrocyte homeostasis may be a necessary element for successful clinical translation. Mitochondria and microRNAs each represent individual targets with multi-modal therapeutic potential. Mitochondria regulate metabolism and apoptosis, while microRNAs have the capacity to bind and inhibit numerous mRNAs. By combining strategies targeted at maintaining astrocyte function during and following cerebral ischemia, a synergistic therapeutic effect may be achieved.
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Affiliation(s)
- Creed M Stary
- Department of Anesthesia, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305, USA
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Nartsissov YR, Tyukina ES, Boronovsky SE, Sheshegova EV. Computer modeling of spatial-time distribution of metabolite concentrations in phantoms of biological objects by example of rat brain pial. Biophysics (Nagoya-shi) 2014. [DOI: 10.1134/s0006350913050102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Peng L, Guo C, Wang T, Li B, Gu L, Wang Z. Methodological limitations in determining astrocytic gene expression. Front Endocrinol (Lausanne) 2013; 4:176. [PMID: 24324456 PMCID: PMC3839565 DOI: 10.3389/fendo.2013.00176] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/31/2013] [Indexed: 01/15/2023] Open
Abstract
Traditionally, astrocytic mRNA and protein expression are studied by in situ hybridization (ISH) and immunohistochemically. This led to the concept that astrocytes lack aralar, a component of the malate-aspartate-shuttle. At least similar aralar mRNA and protein expression in astrocytes and neurons isolated by fluorescence-assisted cell sorting (FACS) reversed this opinion. Demonstration of expression of other astrocytic genes may also be erroneous. Literature data based on morphological methods were therefore compared with mRNA expression in cells obtained by recently developed methods for determination of cell-specific gene expression. All Na,K-ATPase-α subunits were demonstrated by immunohistochemistry (IHC), but there are problems with the cotransporter NKCC1. Glutamate and GABA transporter gene expression was well determined immunohistochemically. The same applies to expression of many genes of glucose metabolism, whereas a single study based on findings in bacterial artificial chromosome (BAC) transgenic animals showed very low astrocytic expression of hexokinase. Gene expression of the equilibrative nucleoside transporters ENT1 and ENT2 was recognized by ISH, but ENT3 was not. The same applies to the concentrative transporters CNT2 and CNT3. All were clearly expressed in FACS-isolated cells, followed by biochemical analysis. ENT3 was enriched in astrocytes. Expression of many nucleoside transporter genes were shown by microarray analysis, whereas other important genes were not. Results in cultured astrocytes resembled those obtained by FACS. These findings call for reappraisal of cellular nucleoside transporter expression. FACS cell yield is small. Further development of cell separation methods to render methods more easily available and less animal and cost consuming and parallel studies of astrocytic mRNA and protein expression by ISH/IHC and other methods are necessary, but new methods also need to be thoroughly checked.
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Affiliation(s)
- Liang Peng
- Department of Clinical Pharmacology, China Medical University, Shenyang, China
- *Correspondence: Liang Peng, College of Basic Medical Sciences, China Medical University, No. 92 Beier Road, Heping District, Shenyang 110001, China e-mail:
| | - Chuang Guo
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Tao Wang
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Baoman Li
- Department of Clinical Pharmacology, China Medical University, Shenyang, China
| | - Li Gu
- Department of Clinical Pharmacology, China Medical University, Shenyang, China
| | - Zhanyou Wang
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
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Jonas EA. Contributions of Bcl-xL to acute and long term changes in bioenergetics during neuronal plasticity. Biochim Biophys Acta Mol Basis Dis 2013; 1842:1168-78. [PMID: 24240091 DOI: 10.1016/j.bbadis.2013.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/23/2022]
Abstract
Mitochondria manufacture and release metabolites and manage calcium during neuronal activity and synaptic transmission, but whether long term alterations in mitochondrial function contribute to the neuronal plasticity underlying changes in organism behavior patterns is still poorly understood. Although normal neuronal plasticity may determine learning, in contrast a persistent decline in synaptic strength or neuronal excitability may portend neurite retraction and eventual somatic death. Anti-death proteins such as Bcl-xL not only provide neuroprotection at the neuronal soma during cell death stimuli, but also appear to enhance neurotransmitter release and synaptic growth and development. It is proposed that Bcl-xL performs these functions through its ability to regulate mitochondrial release of bioenergetic metabolites and calcium, and through its ability to rapidly alter mitochondrial positioning and morphology. Bcl-xL also interacts with proteins that directly alter synaptic vesicle recycling. Bcl-xL translocates acutely to sub-cellular membranes during neuronal activity to achieve changes in synaptic efficacy. After stressful stimuli, pro-apoptotic cleaved delta N Bcl-xL (ΔN Bcl-xL) induces mitochondrial ion channel activity leading to synaptic depression and this is regulated by caspase activation. During physiological states of decreased synaptic stimulation, loss of mitochondrial Bcl-xL and low level caspase activation occur prior to the onset of long term decline in synaptic efficacy. The degree to which Bcl-xL changes mitochondrial membrane permeability may control the direction of change in synaptic strength. The small molecule Bcl-xL inhibitor ABT-737 has been useful in defining the role of Bcl-xL in synaptic processes. Bcl-xL is crucial to the normal health of neurons and synapses and its malfunction may contribute to neurodegenerative disease.
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Affiliation(s)
- Elizabeth A Jonas
- Dept. of Internal Medicine, P.O. Box 208001, Yale University School of Medicine, New Haven, CT 06520, USA; Dept. of Neurobiology, P.O. Box 208020, Yale University School of Medicine, New Haven, CT 06520, USA.
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Fann DYW, Lee SY, Manzanero S, Chunduri P, Sobey CG, Arumugam TV. Pathogenesis of acute stroke and the role of inflammasomes. Ageing Res Rev 2013; 12:941-66. [PMID: 24103368 DOI: 10.1016/j.arr.2013.09.004] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 09/12/2013] [Accepted: 09/19/2013] [Indexed: 12/20/2022]
Abstract
Inflammation is an innate immune response to infection or tissue damage that is designed to limit harm to the host, but contributes significantly to ischemic brain injury following stroke. The inflammatory response is initiated by the detection of acute damage via extracellular and intracellular pattern recognition receptors, which respond to conserved microbial structures, termed pathogen-associated molecular patterns or host-derived danger signals termed damage-associated molecular patterns. Multi-protein complexes known as inflammasomes (e.g. containing NLRP1, NLRP2, NLRP3, NLRP6, NLRP7, NLRP12, NLRC4, AIM2 and/or Pyrin), then process these signals to trigger an effector response. Briefly, signaling through NLRP1 and NLRP3 inflammasomes produces cleaved caspase-1, which cleaves both pro-IL-1β and pro-IL-18 into their biologically active mature pro-inflammatory cytokines that are released into the extracellular environment. This review will describe the molecular structure, cellular signaling pathways and current evidence for inflammasome activation following cerebral ischemia, and the potential for future treatments for stroke that may involve targeting inflammasome formation or its products in the ischemic brain.
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Magi S, Arcangeli S, Castaldo P, Nasti AA, Berrino L, Piegari E, Bernardini R, Amoroso S, Lariccia V. Glutamate-induced ATP synthesis: relationship between plasma membrane Na+/Ca2+ exchanger and excitatory amino acid transporters in brain and heart cell models. Mol Pharmacol 2013; 84:603-14. [PMID: 23913256 DOI: 10.1124/mol.113.087775] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
It is known that glutamate (Glu), the major excitatory amino acid in the central nervous system, can be an essential source for cell energy metabolism. Here we investigated the role of the plasma membrane Na(+)/Ca(2+) exchanger (NCX) and the excitatory amino acid transporters (EAATs) in Glu uptake and recycling mechanisms leading to ATP synthesis. We used different cell lines, such as SH-SY5Y neuroblastoma, C6 glioma and H9c2 as neuronal, glial, and cardiac models, respectively. We first observed that Glu increased ATP production in SH-SY5Y and C6 cells. Pharmacological inhibition of either EAAT or NCX counteracted the Glu-induced ATP synthesis. Furthermore, Glu induced a plasma membrane depolarization and an intracellular Ca(2+) increase, and both responses were again abolished by EAAT and NCX blockers. In line with the hypothesis of a mutual interplay between the activities of EAAT and NCX, coimmunoprecipitation studies showed a physical interaction between them. We expanded our studies on EAAT/NCX interplay in the H9c2 cells. H9c2 expresses EAATs but lacks endogenous NCX1 expression. Glu failed to elicit any significant response in terms of ATP synthesis, cell depolarization, and Ca(2+) increase unless a functional NCX1 was introduced in H9c2 cells by stable transfection. Moreover, these responses were counteracted by EAAT and NCX blockers, as observed in SH-SY5Y and C6 cells. Collectively, these data suggest that plasma membrane EAAT and NCX are both involved in Glu-induced ATP synthesis, with NCX playing a pivotal role.
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Affiliation(s)
- Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University Politecnica of Marche, Ancona, Italy (S.M., S.Ar., P.C., A.A.N., S.Am., V.L.); Department of Experimental Medicine, Second University of Naples, Naples, Italy (L.B., E.P.); and Department of Clinical and Molecular Biomedicine, School of Medicine, University of Catania, Catania, Italy (R.B.)
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Trattner B, Gravot CM, Grothe B, Kunz L. Metabolic Maturation of Auditory Neurones in the Superior Olivary Complex. PLoS One 2013; 8:e67351. [PMID: 23826275 PMCID: PMC3694961 DOI: 10.1371/journal.pone.0067351] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 05/16/2013] [Indexed: 11/25/2022] Open
Abstract
Neuronal activity is energetically costly, but despite its importance, energy production and consumption have been studied in only a few neurone types. Neuroenergetics is of special importance in auditory brainstem nuclei, where neurones exhibit various biophysical adaptations for extraordinary temporal precision and show particularly high firing rates. We have studied the development of energy metabolism in three principal nuclei of the superior olivary complex (SOC) involved in precise binaural processing in the Mongolian gerbil (Meriones unguiculatus). We used immunohistochemistry to quantify metabolic markers for energy consumption (Na+/K+-ATPase) and production (mitochondria, cytochrome c oxidase activity and glucose transporter 3 (GLUT3)). In addition, we calculated neuronal ATP consumption for different postnatal ages (P0–90) based upon published electrophysiological and morphological data. Our calculations relate neuronal processes to the regeneration of Na+ gradients perturbed by neuronal firing, and thus to ATP consumption by Na+/K+-ATPase. The developmental changes of calculated energy consumption closely resemble those of metabolic markers. Both increase before and after hearing onset occurring at P12–13 and reach a plateau thereafter. The increase in Na+/K+-ATPase and mitochondria precedes the rise in GLUT3 levels and is already substantial before hearing onset, whilst GLUT3 levels are scarcely detectable at this age. Based on these findings we assume that auditory inputs crucially contribute to metabolic maturation. In one nucleus, the medial nucleus of the trapezoid body (MNTB), the initial rise in marker levels and calculated ATP consumption occurs distinctly earlier than in the other nuclei investigated, and is almost completed by hearing onset. Our study shows that the mathematical model used is applicable to brainstem neurones. Energy consumption varies markedly between SOC nuclei with their different neuronal properties. Especially for the medial superior olive (MSO), we propose that temporally precise input integration is energetically more costly than the high firing frequencies typical for all SOC nuclei.
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Affiliation(s)
- Barbara Trattner
- Department of Biology II, Division of Neurobiology, Ludwig Maximilians University Munich, Martinsried, Germany
- Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Martinsried, Germany
- * E-mail: (BT); (LK)
| | - Céline Marie Gravot
- Department of Biology II, Division of Neurobiology, Ludwig Maximilians University Munich, Martinsried, Germany
- Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Benedikt Grothe
- Department of Biology II, Division of Neurobiology, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Lars Kunz
- Department of Biology II, Division of Neurobiology, Ludwig Maximilians University Munich, Martinsried, Germany
- * E-mail: (BT); (LK)
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Jha MK, Jeon S, Suk K. Pyruvate Dehydrogenase Kinases in the Nervous System: Their Principal Functions in Neuronal-glial Metabolic Interaction and Neuro-metabolic Disorders. Curr Neuropharmacol 2013; 10:393-403. [PMID: 23730261 PMCID: PMC3520047 DOI: 10.2174/157015912804143586] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/10/2012] [Accepted: 08/28/2012] [Indexed: 01/03/2023] Open
Abstract
Metabolism is involved directly or indirectly in all processes conducted in living cells. The brain, popularly viewed as a neuronal-glial complex, gets most of its energy from the oxygen-dependent metabolism of glucose, and the mitochondrial pyruvate dehydrogenase complex (PDC) plays a key regulatory role during the oxidation of glucose. Pyruvate dehydrogenase kinase (also called PDC kinase or PDK) is a kinase that regulates glucose metabolism by switching off PDC. Four isoforms of PDKs with tissue specific activities have been identified. The metabolisms of neurons and glial cells, especially, those of astroglial cells, are interrelated, and these cells function in an integrated fashion. The energetic coupling between neuronal and astroglial cells is essential to meet the energy requirements of the brain in an efficient way. Accumulating evidence suggests that alterations in the PDKs and/or neuron-astroglia metabolic interactions are associated with the development of several neurological disorders. Here, the authors review the results of recent research efforts that have shed light on the functions of PDKs in the nervous system, particularly on neuron-glia metabolic interactions and neuro-metabolic disorders.
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Affiliation(s)
- Mithilesh Kumar Jha
- Department of Pharmacology, Brain Science & Engineering Institute, Kyungpook National University School of Medicine, Daegu, Korea
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Sidoryk-Wegrzynowicz M, Aschner M. Role of astrocytes in manganese mediated neurotoxicity. BMC Pharmacol Toxicol 2013; 14:23. [PMID: 23594835 PMCID: PMC3637816 DOI: 10.1186/2050-6511-14-23] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/10/2013] [Indexed: 01/08/2023] Open
Abstract
Astrocytes are responsible for numerous aspects of metabolic support, nutrition, control of the ion and neurotransmitter environment in central nervous system (CNS). Failure by astrocytes to support essential neuronal metabolic requirements plays a fundamental role in the pathogenesis of brain injury and the ensuing neuronal death. Astrocyte-neuron interactions play a central role in brain homeostasis, in particular via neurotransmitter recycling functions. Disruption of the glutamine (Gln)/glutamate (Glu) -γ-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons contributes to changes in Glu-ergic and/or GABA-ergic transmission, and is associated with several neuropathological conditions, including manganese (Mn) toxicity. In this review, we discuss recent advances in support of the important roles for astrocytes in normal as well as neuropathological conditions primarily those caused by exposure to Mn.
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A program for solving the brain ischemia problem. Brain Sci 2013; 3:460-503. [PMID: 24961411 PMCID: PMC4061849 DOI: 10.3390/brainsci3020460] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/23/2013] [Accepted: 03/26/2013] [Indexed: 02/01/2023] Open
Abstract
Our recently described nonlinear dynamical model of cell injury is here applied to the problems of brain ischemia and neuroprotection. We discuss measurement of global brain ischemia injury dynamics by time course analysis. Solutions to proposed experiments are simulated using hypothetical values for the model parameters. The solutions solve the global brain ischemia problem in terms of "master bifurcation diagrams" that show all possible outcomes for arbitrary durations of all lethal cerebral blood flow (CBF) decrements. The global ischemia master bifurcation diagrams: (1) can map to a single focal ischemia insult, and (2) reveal all CBF decrements susceptible to neuroprotection. We simulate measuring a neuroprotectant by time course analysis, which revealed emergent nonlinear effects that set dynamical limits on neuroprotection. Using over-simplified stroke geometry, we calculate a theoretical maximum protection of approximately 50% recovery. We also calculate what is likely to be obtained in practice and obtain 38% recovery; a number close to that often reported in the literature. The hypothetical examples studied here illustrate the use of the nonlinear cell injury model as a fresh avenue of approach that has the potential, not only to solve the brain ischemia problem, but also to advance the technology of neuroprotection.
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Villa RF, Ferrari F, Gorini A. Effect of CDP-choline on age-dependent modifications of energy- and glutamate-linked enzyme activities in synaptic and non-synaptic mitochondria from rat cerebral cortex. Neurochem Int 2012; 61:1424-32. [PMID: 23099360 DOI: 10.1016/j.neuint.2012.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 09/14/2012] [Accepted: 10/13/2012] [Indexed: 01/08/2023]
Abstract
The effect of aging and CDP-choline treatment (20 mg kg⁻¹ body weight i.p. for 28 days) on the maximal rates (V(max)) of representative mitochondrial enzyme activities related to Krebs' cycle (citrate synthase, α-ketoglutarate dehydrogenase, malate dehydrogenase), glutamate and related amino acid metabolism (glutamate dehydrogenase, glutamate-oxaloacetate- and glutamate-pyruvate transaminases) were evaluated in non-synaptic and intra-synaptic "light" and "heavy" mitochondria from frontal cerebral cortex of male Wistar rats aged 4, 12, 18 and 24 months. During aging, enzyme activities vary in a complex way respect to the type of mitochondria, i.e. non-synaptic and intra-synaptic. This micro-heterogeneity is an important factor, because energy-related mitochondrial enzyme catalytic properties cause metabolic modifications of physiopathological significance in cerebral tissue in vivo, also discriminating pre- and post-synaptic sites of action for drugs and affecting tissue responsiveness to noxious stimuli. Results show that CDP-choline in vivo treatment enhances cerebral energy metabolism selectively at 18 months, specifically modifying enzyme catalytic activities in non-synaptic and intra-synaptic "light" mitochondrial sub-populations. This confirms that the observed changes in enzyme catalytic activities during aging reflect the bioenergetic state at each single age and the corresponding energy requirements, further proving that in vivo drug treatment is able to interfere with the neuronal energy metabolism.
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Affiliation(s)
- Roberto Federico Villa
- Laboratory of Pharmacology and Molecular Medicine of Central Nervous System, Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy.
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Jakoby P, Schmidt E, Ruminot I, Gutierrez R, Barros LF, Deitmer JW. Higher Transport and Metabolism of Glucose in Astrocytes Compared with Neurons: A Multiphoton Study of Hippocampal and Cerebellar Tissue Slices. Cereb Cortex 2012; 24:222-31. [DOI: 10.1093/cercor/bhs309] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Li B, Hertz L, Peng L. Aralar mRNA and protein levels in neurons and astrocytes freshly isolated from young and adult mouse brain and in maturing cultured astrocytes. Neurochem Int 2012; 61:1325-32. [PMID: 23017600 DOI: 10.1016/j.neuint.2012.09.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/04/2012] [Accepted: 09/13/2012] [Indexed: 10/27/2022]
Abstract
Intense glucose-based energy metabolism and glutamate synthesis by astrocytes require malate-aspartate-shuttle (MAS) activity to regenerate NAD⁺ from NADH formed during glycolysis, since brain lacks significant glycerophosphate shuttle activity. Aralar is a necessary aspartate/glutamate exchanger for MAS function in brain. Based on cytochemical immunoassays the absence of aralar in adult astrocytes was repeatedly reported. This would mean that adult astrocytes must regenerate NAD⁺ by producing lactate from pyruvate, eliminating its use by oxidative and biosynthetic pathways. We alternatively used astrocytes and neurons from adult brain, freshly isolated by fluorescence-activated cell sorting, to determine aralar protein by a specific antibody and its mRNA by real-time PCR. Both protein and mRNA expressions were identical in adult neurons and astrocytes and similar to whole brain levels. The same level of aralar expression was reached in well-differentiated astrocyte cultures, but not until late development, coinciding with the late-maturing brain capability for glutamate formation and degradation.
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Affiliation(s)
- Baoman Li
- Department of Clinical Pharmacology, China Medical University, Shenyang, PR China
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Tian HH, Aziz AR, Png W, Wahid MF, Yeo D, Constance Png AL. Effects of fasting during ramadan month on cognitive function in muslim athletes. Asian J Sports Med 2012; 2:145-53. [PMID: 22375233 PMCID: PMC3289210 DOI: 10.5812/asjsm.34753] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/17/2011] [Indexed: 12/03/2022] Open
Abstract
Purpose Our study aimed to profile the effect of fasting during the Ramadan month on cognitive function in a group of healthy Muslim athletes. Methods Eighteen male athletes underwent computerized neuropsychological testing during (fasting) and after (non-fasting) Ramadan. Diet was standardized, and tests were performed at 0900h and 1600h to characterize potential time-of-day (TOD) interactions. Psychomotor function (processing speed), vigilance (visual attention), visual learning and memory, working memory (executive function), verbal learning and memory were examined. Capillary glucose, body temperature, urine specific gravity, and sleep volume were also recorded. Results Fasting effects were observed for psychomotor function (Cohen's d=1.3, P=0.01) and vigilance (d=0.6, P=0.004), with improved performance at 0900h during fasting; verbal learning and memory was poorer at 1600h (d=-0.8, P=0.03). A TOD effect was present for psychomotor function (d=-0.4, P<0.001), visual learning (d=-0.5, P=0.04), verbal learning and memory (d=-1.3, P=0.001), with poorer performances at 1600h. There was no significant fasting effect on visual learning and working memory. Conclusions Our results show that the effect of fasting on cognition is heterogeneous and domain-specific. Performance in functions requiring sustained rapid responses was better in the morning, declining in the late afternoon, whereas performance in non-speed dependent accuracy measures was more resilient.
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Affiliation(s)
- Ho-Heng Tian
- Changi General Hospital, Singapore
- Corresponding Author: Address: Division of Sports Medicine, Changi General Hospital, 2 Simei St 3, Singapore. E-mail:
| | - Abdul-Rashid Aziz
- Department of Performance Physiology, Singapore Sports Institute, Singapore
| | - Weileen Png
- Department of Sport Nutrition, Singapore Sports Institute, Singapore
| | | | - Donald Yeo
- Department of Neurology, Singapore General Hospital, Singapore
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