1
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Palandt N, Resch C, Unterlechner P, Voshagen L, Winhart VR, Kunz L. Metabolic response of auditory brainstem neurons to their broad physiological activity range. J Neurochem 2024; 168:663-676. [PMID: 38439211 DOI: 10.1111/jnc.16091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 03/06/2024]
Abstract
Neurons exhibit a high energetic need, and the question arises as how they metabolically adapt to changing activity states. This is relevant for interpreting functional neuroimaging in different brain areas. Particularly, neurons with a broad firing range might exhibit metabolic adaptations. Therefore, we studied MNTB (medial nucleus of the trapezoid body) principal neurons, which generate action potentials (APs) at frequencies up to several hundred hertz. We performed the experiments in acute brainstem slices of the Mongolian gerbil (Meriones unguiculatus) at 22.5-24.5°C. Upon electrical stimulation of afferent MNTB fibres with 400 stimuli at varying frequencies, we monitored autofluorescence levels of NAD(P)H and FAD and determined the extremum amplitudes of their biphasic response. Additionally, we compared these data with alterations in O2 concentrations measured with an electrochemical sensor. These O2 changes are prominent since MNTB neurons rely on oxidative phosphorylation as shown by our pharmacological experiments. We calculated the O2 consumption rate as change in O2 concentration divided by stimulus durations, because these periods varied inversely with stimulus frequency as a result of the constant number of 400 stimuli applied. The O2 consumption rate increased with stimulation frequency up to a constant value at 600 Hz; that is, energy demand depends on temporal characteristics of activity despite the same number of stimuli. The rates showed no correlation with peak amplitudes of NAD(P)H or FAD, whilst the values of the two molecules were linearly correlated. This points at the complexity of analysing autofluorescence imaging for quantitative metabolic studies, because these values report only relative net changes of many superimposed oxidative and reductive processes. Monitoring O2 concentration rates is, thus, an important tool to improve the interpretation of NAD(P)H/FAD autofluorescence data, as they do not under all conditions and in all systems appropriately reflect the metabolic activity or energy demand.
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Affiliation(s)
- Nicola Palandt
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
- Graduate School of Systemic Neurosciences (GSN), Ludwig-Maximillians-Universität (LMU), Munich, Germany
| | - Cibell Resch
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
| | - Patricia Unterlechner
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
| | - Lukas Voshagen
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
| | - Valentin R Winhart
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
- Graduate School of Systemic Neurosciences (GSN), Ludwig-Maximillians-Universität (LMU), Munich, Germany
| | - Lars Kunz
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximillians-Universität (LMU), Munich, Germany
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2
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Lujan BJ, Singh M, Singh A, Renden RB. Developmental shift to mitochondrial respiration for energetic support of sustained transmission during maturation at the calyx of Held. J Neurophysiol 2021; 126:976-996. [PMID: 34432991 PMCID: PMC8560424 DOI: 10.1152/jn.00333.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 11/24/2022] Open
Abstract
A considerable amount of energy is expended following presynaptic activity to regenerate electrical polarization and maintain efficient release and recycling of neurotransmitter. Mitochondria are the major suppliers of neuronal energy, generating ATP via oxidative phosphorylation. However, the specific utilization of energy from cytosolic glycolysis rather than mitochondrial respiration at the presynaptic terminal during synaptic activity remains unclear and controversial. We use a synapse specialized for high-frequency transmission in mice, the calyx of Held, to test the sources of energy used to maintain energy during short activity bursts (<1 s) and sustained neurotransmission (30-150 s). We dissect the role of presynaptic glycolysis versus mitochondrial respiration by acutely and selectively blocking these ATP-generating pathways in a synaptic preparation where mitochondria and synaptic vesicles are prolific, under near-physiological conditions. Surprisingly, if either glycolysis or mitochondrial ATP production is intact, transmission during repetitive short bursts of activity is not affected. In slices from young animals before the onset of hearing, where the synapse is not yet fully specialized, both glycolytic and mitochondrial ATP production are required to support sustained, high-frequency neurotransmission. In mature synapses, sustained transmission relies exclusively on mitochondrial ATP production supported by bath lactate, but not glycolysis. At both ages, we observe that action potential propagation begins to fail before defects in synaptic vesicle recycling. Our data describe a specific metabolic profile to support high-frequency information transmission at the mature calyx of Held, shifting during postnatal synaptic maturation from glycolysis to rely on monocarboxylates as a fuel source.NEW & NOTEWORTHY We dissect the role of presynaptic glycolysis versus mitochondrial respiration in supporting high-frequency neurotransmission, by acutely blocking these ATP-generating pathways at a synapse tuned for high-frequency transmission. We find that massive energy expenditure is required to generate failure when only one pathway is inhibited. Action potential propagation is lost before impaired synaptic vesicle recycling. Synaptic transmission is exclusively dependent on oxidative phosphorylation in mature synapses, indicating presynaptic glycolysis may be dispensable for ATP maintenance.
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Affiliation(s)
- Brendan J Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Mahendra Singh
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Abhyudai Singh
- Electrical & Computer Engineering, University of Delaware, Newark, Delaware
| | - Robert B Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
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3
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Díaz-García CM, Meyer DJ, Nathwani N, Rahman M, Martínez-François JR, Yellen G. The distinct roles of calcium in rapid control of neuronal glycolysis and the tricarboxylic acid cycle. eLife 2021; 10:e64821. [PMID: 33555254 PMCID: PMC7870136 DOI: 10.7554/elife.64821] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/26/2021] [Indexed: 12/31/2022] Open
Abstract
When neurons engage in intense periods of activity, the consequent increase in energy demand can be met by the coordinated activation of glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. However, the trigger for glycolytic activation is unknown and the role for Ca2+ in the mitochondrial responses has been debated. Using genetically encoded fluorescent biosensors and NAD(P)H autofluorescence imaging in acute hippocampal slices, here we find that Ca2+ uptake into the mitochondria is responsible for the buildup of mitochondrial NADH, probably through Ca2+ activation of dehydrogenases in the TCA cycle. In the cytosol, we do not observe a role for the Ca2+/calmodulin signaling pathway, or AMPK, in mediating the rise in glycolytic NADH in response to acute stimulation. Aerobic glycolysis in neurons is triggered mainly by the energy demand resulting from either Na+ or Ca2+ extrusion, and in mouse dentate granule cells, Ca2+ creates the majority of this demand.
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Affiliation(s)
| | - Dylan J Meyer
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Nidhi Nathwani
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Mahia Rahman
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | | | - Gary Yellen
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
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4
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Cserép C, Pósfai B, Lénárt N, Fekete R, László ZI, Lele Z, Orsolits B, Molnár G, Heindl S, Schwarcz AD, Ujvári K, Környei Z, Tóth K, Szabadits E, Sperlágh B, Baranyi M, Csiba L, Hortobágyi T, Maglóczky Z, Martinecz B, Szabó G, Erdélyi F, Szipőcs R, Tamkun MM, Gesierich B, Duering M, Katona I, Liesz A, Tamás G, Dénes Á. Microglia monitor and protect neuronal function through specialized somatic purinergic junctions. Science 2019; 367:528-537. [PMID: 31831638 DOI: 10.1126/science.aax6752] [Citation(s) in RCA: 348] [Impact Index Per Article: 69.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 10/14/2019] [Accepted: 12/03/2019] [Indexed: 12/16/2022]
Abstract
Microglia are the main immune cells in the brain and have roles in brain homeostasis and neurological diseases. Mechanisms underlying microglia-neuron communication remain elusive. Here, we identified an interaction site between neuronal cell bodies and microglial processes in mouse and human brain. Somatic microglia-neuron junctions have a specialized nanoarchitecture optimized for purinergic signaling. Activity of neuronal mitochondria was linked with microglial junction formation, which was induced rapidly in response to neuronal activation and blocked by inhibition of P2Y12 receptors. Brain injury-induced changes at somatic junctions triggered P2Y12 receptor-dependent microglial neuroprotection, regulating neuronal calcium load and functional connectivity. Thus, microglial processes at these junctions could potentially monitor and protect neuronal functions.
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Affiliation(s)
- Csaba Cserép
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Pósfai
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Nikolett Lénárt
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Rebeka Fekete
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Zsófia I László
- Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary.,Momentum Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Zsolt Lele
- Momentum Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Barbara Orsolits
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Gábor Molnár
- MTA-SZTE Research Group for Cortical Microcircuits of the Hungarian Academy of Sciences, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Steffanie Heindl
- Institute for Stroke and Dementia Research, Ludwig-Maximilians-University, Munich, Germany
| | - Anett D Schwarcz
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Katinka Ujvári
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Zsuzsanna Környei
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Krisztina Tóth
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Eszter Szabadits
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Beáta Sperlágh
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Budapest, Hungary
| | - Mária Baranyi
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Budapest, Hungary
| | - László Csiba
- MTA-DE Cerebrovascular and Neurodegenerative Research Group, Department of Neurology, University of Debrecen, Debrecen, Hungary
| | - Tibor Hortobágyi
- Institute of Pathology, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Old Age Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.,Centre for Age-Related Medicine, SESAM, Stavanger University Hospital, Stavanger, Norway
| | - Zsófia Maglóczky
- Human Brain Research Laboratory, Institute of Experimental Medicine, Budapest, Hungary
| | - Bernadett Martinecz
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Gábor Szabó
- Medical Gene Technology Unit, Institute of Experimental Medicine, Budapest, Hungary
| | - Ferenc Erdélyi
- Medical Gene Technology Unit, Institute of Experimental Medicine, Budapest, Hungary
| | - Róbert Szipőcs
- Institute for Solid State Physics and Optics of Wigner RCP, Budapest, Hungary
| | - Michael M Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Benno Gesierich
- Institute for Stroke and Dementia Research, Ludwig-Maximilians-University, Munich, Germany
| | - Marco Duering
- Institute for Stroke and Dementia Research, Ludwig-Maximilians-University, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - István Katona
- Momentum Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Arthur Liesz
- Institute for Stroke and Dementia Research, Ludwig-Maximilians-University, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Gábor Tamás
- MTA-SZTE Research Group for Cortical Microcircuits of the Hungarian Academy of Sciences, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Ádám Dénes
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.
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5
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Klimova N, Long A, Kristian T. Nicotinamide mononucleotide alters mitochondrial dynamics by SIRT3-dependent mechanism in male mice. J Neurosci Res 2019; 97:975-990. [PMID: 30801823 PMCID: PMC6565489 DOI: 10.1002/jnr.24397] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/22/2019] [Accepted: 01/22/2019] [Indexed: 01/02/2023]
Abstract
Nicotinamide adenine dinucleotide (NAD+ ) is a central signaling molecule and enzyme cofactor that is involved in a variety of fundamental biological processes. NAD+ levels decline with age, neurodegenerative conditions, acute brain injury, and in obesity or diabetes. Loss of NAD+ results in impaired mitochondrial and cellular functions. Administration of NAD+ precursor, nicotinamide mononucleotide (NMN), has shown to improve mitochondrial bioenergetics, reverse age-associated physiological decline, and inhibit postischemic NAD+ degradation and cellular death. In this study, we identified a novel link between NAD+ metabolism and mitochondrial dynamics. A single dose (62.5 mg/kg) of NMN, administered to male mice, increases hippocampal mitochondria NAD+ pools for up to 24 hr posttreatment and drives a sirtuin 3 (SIRT3)-mediated global decrease in mitochondrial protein acetylation. This results in a reduction of hippocampal reactive oxygen species levels via SIRT3-driven deacetylation of mitochondrial manganese superoxide dismutase. Consequently, mitochondria in neurons become less fragmented due to lower interaction of phosphorylated fission protein, dynamin-related protein 1 (pDrp1 [S616]), with mitochondria. In conclusion, manipulation of mitochondrial NAD+ levels by NMN results in metabolic changes that protect mitochondria against reactive oxygen species and excessive fragmentation, offering therapeutic approaches for pathophysiologic stress conditions.
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Affiliation(s)
- Nina Klimova
- Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), Baltimore, Maryland 21201, USA
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Aaron Long
- Veterans Affairs Maryland Health Center System, 10 North Greene Street, Baltimore, MD 21201
| | - Tibor Kristian
- Veterans Affairs Maryland Health Center System, 10 North Greene Street, Baltimore, MD 21201
- Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), Baltimore, Maryland 21201, USA
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6
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Köhler S, Winkler U, Sicker M, Hirrlinger J. NBCe1 mediates the regulation of the NADH/NAD + redox state in cortical astrocytes by neuronal signals. Glia 2018; 66:2233-2245. [PMID: 30208253 DOI: 10.1002/glia.23504] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/19/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022]
Abstract
Astrocytes are a glial cell type, which is indispensable for brain energy metabolism. Within cells, the NADH/NAD+ redox state is a crucial node in metabolism connecting catabolic pathways to oxidative phosphorylation and ATP production in mitochondria. To characterize the dynamics of the intracellular NADH/NAD+ redox state in cortical astrocytes Peredox, a genetically encoded sensor for the NADH/NAD+ redox state, was expressed in cultured cortical astrocytes as well as in cortical astrocytes in acutely isolated brain slices. Calibration of the sensor in cultured astrocytes revealed a mean basal cytosolic NADH/NAD+ redox ratio of about 0.01; however, with a broad distribution and heterogeneity in the cell population, which was mirrored by a heterogeneous basal cellular concentration of lactate. Inhibition of glucose uptake decreased the NADH/NAD+ redox state while inhibition of lactate dehydrogenase or of lactate release resulted in an increase in the NADH/NAD+ redox ratio. Furthermore, the NADH/NAD+ redox state was regulated by the extracellular concentration of K+ , and application of the neurotransmitters ATP or glutamate increased the NADH/NAD+ redox state dependent on purinergic receptors and glutamate uptake, respectively. This regulation by K+ , ATP, and glutamate involved NBCe1 mediated sodium-bicarbonate transport. These results demonstrate that the NADH/NAD+ redox state in astrocytes is a metabolic node regulated by neuronal signals reflecting physiological activity, most likely contributing to adjust astrocytic metabolism to energy demand of the brain.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Marit Sicker
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
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7
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Yellen G. Fueling thought: Management of glycolysis and oxidative phosphorylation in neuronal metabolism. J Cell Biol 2018; 217:2235-2246. [PMID: 29752396 PMCID: PMC6028533 DOI: 10.1083/jcb.201803152] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 04/30/2018] [Accepted: 05/02/2018] [Indexed: 01/02/2023] Open
Abstract
Yellen reviews how cellular metabolism responds acutely to the intense energy requirements of neurons when they are stimulated. The brain’s energy demands are remarkable both in their intensity and in their moment-to-moment dynamic range. This perspective considers the evidence for Warburg-like aerobic glycolysis during the transient metabolic response of the brain to acute activation, and it particularly addresses the cellular mechanisms that underlie this metabolic response. The temporary uncoupling between glycolysis and oxidative phosphorylation led to the proposal of an astrocyte-to-neuron lactate shuttle whereby during stimulation, lactate produced by increased glycolysis in astrocytes is taken up by neurons as their primary energy source. However, direct evidence for this idea is lacking, and evidence rather supports that neurons have the capacity to increase their own glycolysis in response to stimulation; furthermore, neurons may export rather than import lactate in response to stimulation. The possible cellular mechanisms for invoking metabolic resupply of energy in neurons are also discussed, in particular the roles of feedback signaling via adenosine diphosphate and feedforward signaling by calcium ions.
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Affiliation(s)
- Gary Yellen
- Department of Neurobiology, Harvard Medical School, Boston, MA
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8
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Chen G, Carter RE, Cleary JD, Reid TS, Ranum LP, Swanson MS, Ebner TJ. Altered levels of the splicing factor muscleblind modifies cerebral cortical function in mouse models of myotonic dystrophy. Neurobiol Dis 2018; 112:35-48. [PMID: 29331264 PMCID: PMC5859959 DOI: 10.1016/j.nbd.2018.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 01/18/2023] Open
Abstract
Myotonic dystrophy (DM) is a progressive, multisystem disorder affecting skeletal muscle, heart, and central nervous system. In both DM1 and DM2, microsatellite expansions of CUG and CCUG RNA repeats, respectively, accumulate and disrupt functions of alternative splicing factors, including muscleblind (MBNL) proteins. Grey matter loss and white matter changes, including the corpus callosum, likely underlie cognitive and executive function deficits in DM patients. However, little is known how cerebral cortical circuitry changes in DM. Here, flavoprotein optical imaging was used to assess local and contralateral responses to intracortical motor cortex stimulation in DM-related mouse models. In control mice, brief train stimulation generated ipsilateral and contralateral homotopic fluorescence increases, the latter mediated by the corpus callosum. Single pulse stimulation produced an excitatory response with an inhibitory-like surround response mediated by GABAA receptors. In a mouse model of DM2 (Mbnl2 KO), we observed prolonged and increased responsiveness to train stimulation and loss of the inhibition from single pulse stimulation. Conversely, mice overexpressing human MBNL1 (MBNL1-OE) exhibited decreased contralateral response to train stimulation and reduction of inhibitory-like surround to single pulse stimulation. Therefore, altering levels of two key DM-associated splicing factors modifies functions of local cortical circuits and contralateral responses mediated through the corpus callosum.
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Affiliation(s)
- Gang Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - John D Cleary
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Tammy S Reid
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Laura P Ranum
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Maurice S Swanson
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA.
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9
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Bioenergetic state regulates innate inflammatory responses through the transcriptional co-repressor CtBP. Nat Commun 2017; 8:624. [PMID: 28935892 PMCID: PMC5608947 DOI: 10.1038/s41467-017-00707-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Accepted: 07/21/2017] [Indexed: 01/04/2023] Open
Abstract
The innate inflammatory response contributes to secondary injury in brain trauma and other disorders. Metabolic factors such as caloric restriction, ketogenic diet, and hyperglycemia influence the inflammatory response, but how this occurs is unclear. Here, we show that glucose metabolism regulates pro-inflammatory NF-κB transcriptional activity through effects on the cytosolic NADH:NAD+ ratio and the NAD(H) sensitive transcriptional co-repressor CtBP. Reduced glucose availability reduces the NADH:NAD+ ratio, NF-κB transcriptional activity, and pro-inflammatory gene expression in macrophages and microglia. These effects are inhibited by forced elevation of NADH, reduced expression of CtBP, or transfection with an NAD(H) insensitive CtBP, and are replicated by a synthetic peptide that inhibits CtBP dimerization. Changes in the NADH:NAD+ ratio regulate CtBP binding to the acetyltransferase p300, and regulate binding of p300 and the transcription factor NF-κB to pro-inflammatory gene promoters. These findings identify a mechanism by which alterations in cellular glucose metabolism can influence cellular inflammatory responses. Several metabolic factors affect cellular glucose metabolism as well as the innate inflammatory response. Here, the authors show that glucose metabolism regulates pro-inflammatory responses through effects on the cytosolic NADH:NAD+ ratio and the NAD(H)-sensitive transcription co-repressor CtBP.
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10
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Díaz-García CM, Mongeon R, Lahmann C, Koveal D, Zucker H, Yellen G. Neuronal Stimulation Triggers Neuronal Glycolysis and Not Lactate Uptake. Cell Metab 2017; 26:361-374.e4. [PMID: 28768175 PMCID: PMC5559896 DOI: 10.1016/j.cmet.2017.06.021] [Citation(s) in RCA: 289] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 04/29/2017] [Accepted: 06/27/2017] [Indexed: 01/05/2023]
Abstract
Proper brain function requires a substantial energy supply, up to 20% of whole-body energy in humans, and brain activation produces large dynamic variations in energy demand. While local increases in cerebral blood flow are well known, the cellular responses to energy demand are controversial. During brain excitation, glycolysis of glucose to lactate temporarily exceeds the rate of mitochondrial fuel oxidation; although the increased energy demand occurs mainly within neurons, some have suggested this glycolysis occurs mainly in astrocytes, which then shuttle lactate to neurons as their primary fuel. Using metabolic biosensors in acute hippocampal slices and brains of awake mice, we find that neuronal metabolic responses to stimulation do not depend on astrocytic stimulation by glutamate release, nor do they require neuronal uptake of lactate; instead they reflect increased direct glucose consumption by neurons. Neuronal glycolysis temporarily outstrips oxidative metabolism, and provides a rapid response to increased energy demand.
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Affiliation(s)
| | - Rebecca Mongeon
- Department of Neurobiology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Carolina Lahmann
- Department of Neurobiology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Dorothy Koveal
- Department of Neurobiology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Hannah Zucker
- Department of Neurobiology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Gary Yellen
- Department of Neurobiology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
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11
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Lourenço CF, Ledo A, Barbosa RM, Laranjinha J. Neurovascular-neuroenergetic coupling axis in the brain: master regulation by nitric oxide and consequences in aging and neurodegeneration. Free Radic Biol Med 2017; 108:668-682. [PMID: 28435052 DOI: 10.1016/j.freeradbiomed.2017.04.026] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 02/21/2017] [Accepted: 04/18/2017] [Indexed: 02/08/2023]
Abstract
The strict energetic demands of the brain require that nutrient supply and usage be fine-tuned in accordance with the specific temporal and spatial patterns of ever-changing levels of neuronal activity. This is achieved by adjusting local cerebral blood flow (CBF) as a function of activity level - neurovascular coupling - and by changing how energy substrates are metabolized and shuttled amongst astrocytes and neurons - neuroenergetic coupling. Both activity-dependent increase of CBF and O2 and glucose utilization by active neural cells are inextricably linked, establishing a functional metabolic axis in the brain, the neurovascular-neuroenergetic coupling axis. This axis incorporates and links previously independent processes that need to be coordinated in the normal brain. We here review evidence supporting the role of neuronal-derived nitric oxide (•NO) as the master regulator of this axis. Nitric oxide is produced in tight association with glutamatergic activation and, diffusing several cell diameters, may interact with different molecular targets within each cell type. Hemeproteins such as soluble guanylate cyclase, cytochrome c oxidase and hemoglobin, with which •NO reacts at relatively fast rates, are but a few of the key in determinants of the regulatory role of •NO in the neurovascular-neuroenergetic coupling axis. Accordingly, critical literature supporting this concept is discussed. Moreover, in view of the controversy regarding the regulation of catabolism of different neural cells, we further discuss key aspects of the pathways through which •NO specifically up-regulates glycolysis in astrocytes, supporting lactate shuttling to neurons for oxidative breakdown. From a biomedical viewpoint, derailment of neurovascular-neuroenergetic axis is precociously linked to aberrant brain aging, cognitive impairment and neurodegeneration. Thus, we summarize current knowledge of how both neurovascular and neuroenergetic coupling are compromised in aging, traumatic brain injury, epilepsy and age-associated neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, suggesting that a shift in cellular redox balance may contribute to divert •NO bioactivity from regulation to dysfunction.
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Affiliation(s)
- Cátia F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Ana Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Rui M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - João Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
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12
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RIBEYE(B)-domain binds to lipid components of synaptic vesicles in an NAD(H)-dependent, redox-sensitive manner. Biochem J 2017; 474:1205-1220. [PMID: 28202712 DOI: 10.1042/bcj20160886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 02/14/2017] [Accepted: 02/14/2017] [Indexed: 12/26/2022]
Abstract
Synaptic ribbons are needed for fast and continuous exocytosis in ribbon synapses. RIBEYE is a main protein component of synaptic ribbons and is necessary to build the synaptic ribbon. RIBEYE consists of a unique A-domain and a carboxyterminal B-domain, which binds NAD(H). Within the presynaptic terminal, the synaptic ribbons are in physical contact with large numbers of synaptic vesicle (SV)s. How this physical contact between ribbons and synaptic vesicles is established at a molecular level is not well understood. In the present study, we demonstrate that the RIBEYE(B)-domain can directly interact with lipid components of SVs using two different sedimentation assays with liposomes of defined chemical composition. Similar binding results were obtained with a SV-containing membrane fraction. The binding of liposomes to RIBEYE(B) depends upon the presence of a small amount of lysophospholipids present in the liposomes. Interestingly, binding of liposomes to RIBEYE(B) depends on NAD(H) in a redox-sensitive manner. The binding is enhanced by NADH, the reduced form, and is inhibited by NAD+, the oxidized form. Lipid-mediated attachment of vesicles is probably part of a multi-step process that also involves additional, protein-dependent processes.
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13
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Uytingco CR, Puche AC, Munger SD. Using Intrinsic Flavoprotein and NAD(P)H Imaging to Map Functional Circuitry in the Main Olfactory Bulb. PLoS One 2016; 11:e0165342. [PMID: 27902689 PMCID: PMC5130181 DOI: 10.1371/journal.pone.0165342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/10/2016] [Indexed: 12/02/2022] Open
Abstract
Neurons exhibit strong coupling of electrochemical and metabolic activity. Increases in intrinsic fluorescence from either oxidized flavoproteins or reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] in the mitochondria have been used as an indicator of neuronal activity for the functional mapping of neural circuits. However, this technique has not been used to investigate the flow of olfactory information within the circuitry of the main olfactory bulb (MOB). We found that intrinsic flavoprotein fluorescence signals induced by electrical stimulation of single glomeruli displayed biphasic responses within both the glomerular (GL) and external plexiform layers (EPL) of the MOB. Pharmacological blockers of mitochondrial activity, voltage-gated Na+ channels, or ionotropic glutamate receptors abolished stimulus-dependent flavoprotein responses. Blockade of GABAA receptors enhanced the amplitude and spatiotemporal spread of the flavoprotein signals, indicating an important role for inhibitory neurotransmission in shaping the spread of neural activity in the MOB. Stimulus-dependent spread of fluorescence across the GL and EPL displayed a spatial distribution consistent with that of individual glomerular microcircuits mapped by neuroanatomic tract tracing. These findings demonstrated the feasibility of intrinsic fluorescence imaging in the olfactory systems and provided a new tool to examine the functional circuitry of the MOB.
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Affiliation(s)
- Cedric R Uytingco
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Adam C Puche
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Steven D Munger
- Center for Smell and Taste, University of Florida, Gainesville, Florida, United States of America.,Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America.,Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, Florida, United States of America
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14
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Lujan B, Kushmerick C, Banerjee TD, Dagda RK, Renden R. Glycolysis selectively shapes the presynaptic action potential waveform. J Neurophysiol 2016; 116:2523-2540. [PMID: 27605535 DOI: 10.1152/jn.00629.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/05/2016] [Indexed: 11/22/2022] Open
Abstract
Mitochondria are major suppliers of cellular energy in neurons; however, utilization of energy from glycolysis vs. mitochondrial oxidative phosphorylation (OxPhos) in the presynaptic compartment during neurotransmission is largely unknown. Using presynaptic and postsynaptic recordings from the mouse calyx of Held, we examined the effect of acute selective pharmacological inhibition of glycolysis or mitochondrial OxPhos on multiple mechanisms regulating presynaptic function. Inhibition of glycolysis via glucose depletion and iodoacetic acid (1 mM) treatment, but not mitochondrial OxPhos, rapidly altered transmission, resulting in highly variable, oscillating responses. At reduced temperature, this same treatment attenuated synaptic transmission because of a smaller and broader presynaptic action potential (AP) waveform. We show via experimental manipulation and ion channel modeling that the altered AP waveform results in smaller Ca2+ influx, resulting in attenuated excitatory postsynaptic currents (EPSCs). In contrast, inhibition of mitochondria-derived ATP production via extracellular pyruvate depletion and bath-applied oligomycin (1 μM) had no significant effect on Ca2+ influx and did not alter the AP waveform within the same time frame (up to 30 min), and the resultant EPSC remained unaffected. Glycolysis, but not mitochondrial OxPhos, is thus required to maintain basal synaptic transmission at the presynaptic terminal. We propose that glycolytic enzymes are closely apposed to ATP-dependent ion pumps on the presynaptic membrane. Our results indicate a novel mechanism for the effect of hypoglycemia on neurotransmission. Attenuated transmission likely results from a single presynaptic mechanism at reduced temperature: a slower, smaller AP, before and independent of any effect on synaptic vesicle release or receptor activity.
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Affiliation(s)
- Brendan Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil; and
| | - Tania Das Banerjee
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Ruben K Dagda
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Robert Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada;
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15
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Nicotinamide mononucleotide inhibits post-ischemic NAD(+) degradation and dramatically ameliorates brain damage following global cerebral ischemia. Neurobiol Dis 2016; 95:102-10. [PMID: 27425894 DOI: 10.1016/j.nbd.2016.07.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/17/2016] [Accepted: 07/13/2016] [Indexed: 01/22/2023] Open
Abstract
Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor for multiple cellular metabolic reactions and has a central role in energy production. Brain ischemia depletes NAD(+) pools leading to bioenergetics failure and cell death. Nicotinamide mononucleotide (NMN) is utilized by the NAD(+) salvage pathway enzyme, nicotinamide adenylyltransferase (Nmnat) to generate NAD(+). Therefore, we examined whether NMN could protect against ischemic brain damage. Mice were subjected to transient forebrain ischemia and treated with NMN or vehicle at the start of reperfusion or 30min after the ischemic insult. At 2, 4, and 24h of recovery, the proteins poly-ADP-ribosylation (PAR), hippocampal NAD(+) levels, and expression levels of NAD(+) salvage pathway enzymes were determined. Furthermore, animal's neurologic outcome and hippocampal CA1 neuronal death was assessed after six days of reperfusion. NMN (62.5mg/kg) dramatically ameliorated the hippocampal CA1 injury and significantly improved the neurological outcome. Additionally, the post-ischemic NMN treatment prevented the increase in PAR formation and NAD(+) catabolism. Since the NMN administration did not affect animal's temperature, blood gases or regional cerebral blood flow during recovery, the protective effect was not a result of altered reperfusion conditions. These data suggest that administration of NMN at a proper dosage has a strong protective effect against ischemic brain injury.
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16
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Rösner J, Liotta A, Angamo EA, Spies C, Heinemann U, Kovács R. Minimizing photodecomposition of flavin adenine dinucleotide fluorescence by the use of pulsed LEDs. J Microsc 2016; 264:215-223. [PMID: 27368071 DOI: 10.1111/jmi.12436] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/27/2016] [Accepted: 05/30/2016] [Indexed: 01/08/2023]
Abstract
Dynamic alterations in flavin adenine dinucleotide (FAD) fluorescence permit insight into energy metabolism-dependent changes of intramitochondrial redox potential. Monitoring FAD fluorescence in living tissue is impeded by photobleaching, restricting the length of microfluorimetric recordings. In addition, photodecomposition of these essential electron carriers negatively interferes with energy metabolism and viability of the biological specimen. Taking advantage of pulsed LED illumination, here we determined the optimal excitation settings giving the largest fluorescence yield with the lowest photobleaching and interference with metabolism in hippocampal brain slices. The effects of FAD bleaching on energy metabolism and viability were studied by monitoring tissue pO2 , field potentials and changes in extracellular potassium concentration ([K+ ]o ). Photobleaching with continuous illumination consisted of an initial exponential decrease followed by a nearly linear decay. The exponential decay was significantly decelerated with pulsed illumination. Pulse length of 5 ms was sufficient to reach a fluorescence output comparable to continuous illumination, whereas further increasing duration increased photobleaching. Similarly, photobleaching increased with shortening of the interpulse interval. Photobleaching was partially reversible indicating the existence of a transient nonfluorescent flavin derivative. Pulsed illumination decreased FAD photodecomposition, improved slice viability and reproducibility of stimulus-induced FAD, field potential, [K+ ]o and pO2 changes as compared to continuous illumination.
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Affiliation(s)
- J Rösner
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - A Liotta
- Department of Anesthesiology and Intensive Care Medicine, Charité Universitätsmedizin, Berlin
| | - E A Angamo
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - C Spies
- Department of Anesthesiology and Intensive Care Medicine, Charité Universitätsmedizin, Berlin
| | - U Heinemann
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - R Kovács
- Institute for Neurophysiology, Charité Universitätsmedizin, Berlin.
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17
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Kann O, Hollnagel JO, Elzoheiry S, Schneider J. Energy and Potassium Ion Homeostasis during Gamma Oscillations. Front Mol Neurosci 2016; 9:47. [PMID: 27378847 PMCID: PMC4909733 DOI: 10.3389/fnmol.2016.00047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/30/2016] [Indexed: 12/21/2022] Open
Abstract
Fast neuronal network oscillations in the gamma frequency band (30-100 Hz) occur in various cortex regions, require timed synaptic excitation and inhibition with glutamate and GABA, respectively, and are associated with higher brain functions such as sensory perception, attentional selection and memory formation. However, little is known about energy and ion homeostasis during the gamma oscillation. Recent studies addressed this topic in slices of the rodent hippocampus using cholinergic and glutamatergic receptor models of gamma oscillations (GAM). Methods with high spatial and temporal resolution were applied in vitro, such as electrophysiological recordings of local field potential (LFP) and extracellular potassium concentration ([K(+)]o), live-cell fluorescence imaging of nicotinamide adenine dinucleotide (phosphate) and flavin adenine dinucleotide [NAD(P)H and FAD, respectively] (cellular redox state), and monitoring of the interstitial partial oxygen pressure (pO2) in depth profiles with microsensor electrodes, including mathematical modeling. The main findings are: (i) GAM are associated with high oxygen consumption rate and significant changes in the cellular redox state, indicating rapid adaptations in glycolysis and oxidative phosphorylation; (ii) GAM are accompanied by fluctuating elevations in [K(+)]o of less than 0.5 mmol/L from baseline, likely reflecting effective K(+)-uptake mechanisms of neuron and astrocyte compartments; and (iii) GAM are exquisitely sensitive to metabolic stress induced by lowering oxygen availability or by pharmacological inhibition of the mitochondrial respiratory chain. These findings reflect precise cellular adaptations to maintain adenosine-5'-triphosphate (ATP), ion and neurotransmitter homeostasis and thus neural excitability and synaptic signaling during GAM. Conversely, the exquisite sensitivity of GAM to metabolic stress might significantly contribute the exceptional vulnerability of higher brain functions in brain disease.
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Affiliation(s)
- Oliver Kann
- Institute of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany; Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelberg, Germany
| | - Jan-Oliver Hollnagel
- Institute of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany; Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelberg, Germany
| | - Shehabeldin Elzoheiry
- Institute of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany; Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelberg, Germany
| | - Justus Schneider
- Institute of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany; Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelberg, Germany
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18
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Karthick C, Periyasamy S, Jayachandran KS, Anusuyadevi M. Intrahippocampal Administration of Ibotenic Acid Induced Cholinergic Dysfunction via NR2A/NR2B Expression: Implications of Resveratrol against Alzheimer Disease Pathophysiology. Front Mol Neurosci 2016; 9:28. [PMID: 27199654 PMCID: PMC4844917 DOI: 10.3389/fnmol.2016.00028] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/01/2016] [Indexed: 01/27/2023] Open
Abstract
Although several drugs revealed moderate amelioration of symptoms, none of them have sufficient potency to prevent or reverse the progression toward Alzheimer's disease (AD) pathology. Resveratrol (RSV), a polyphenolic compound has shown an outstanding therapeutic effect on a broad spectrum of diseases like age-associated neurodegeneration, inflammation etc. The present study was thus conducted to assess the therapeutic efficacy of RSV in ameliorating the deleterious effects of Ibotenic acid (IBO) in male Wistar rats. Stereotactic intrahippocampal administration of IBO (5 μg/μl) lesioned rats impairs cholinergic transmission, learning and memory performance that is rather related to AD and thus chosen as a suitable model to understand the drug efficacy in preventing AD pathophysiology. Since IBO is an agonist of glutamate, it is expected to exhibit an excitotoxic effect by altering glutamatergic receptors like NMDA receptor. The current study displayed significant alterations in the mRNA expression of NR2A and NR2B subunits of NMDA receptors, and further it is surprising to note that cholinergic receptors decreased in expression particularly α7-nAChR with increased m1AChR. RSV administration (20 mg/kg body weight, i.p.) significantly reduced these changes in IBO induced rats. Glutamatergic and cholinergic receptor alterations were associated with significant changes in the behavioral parameters of rats induced by IBO. While RSV improved spatial learning performance, attenuated immobility, and improvised open field activity in IBO induced rats. NR2B activation in the present study might mediate cell death through oxidative stress that form the basis of abnormal behavioral pattern in IBO induced rats. Interestingly, RSV that could efficiently encounter oxidative stress have significantly decreased stress markers viz., nitrite, PCO, and MDA levels by enhancing antioxidant status. Histopathological analysis displayed significant reduction in the hippocampal pyramidal layer thickness and live neurons in IBO induced rats, with slight pathological changes in the entorhinal cortex (EC) of rat brain, which was prevented on RSV administration. Our study thus concludes that RSV administration significantly ameliorated the deleterious effects in the IBO lesioned rat model for AD by alleviating cholinergic pathways, reducing oxidative stress and thereby improving spatial memory.
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Affiliation(s)
- Chennakesavan Karthick
- Molecular Gerontology Laboratory, Department of Biochemistry (DST-FIST Sponsored), Bharathidasan University Tiruchirappalli, India
| | - Sabapathy Periyasamy
- Molecular Gerontology Laboratory, Department of Biochemistry (DST-FIST Sponsored), Bharathidasan University Tiruchirappalli, India
| | - Kesavan S Jayachandran
- Molecular Cardiology and Drug Discovery Laboratory, Department of Bioinformatics, Bharathidasan University Tiruchirappalli, India
| | - Muthuswamy Anusuyadevi
- Molecular Gerontology Laboratory, Department of Biochemistry (DST-FIST Sponsored), Bharathidasan University Tiruchirappalli, India
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19
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Reyes RC, Cittolin-Santos GF, Kim JE, Won SJ, Brennan-Minnella AM, Katz M, Glass GA, Swanson RA. Neuronal Glutathione Content and Antioxidant Capacity can be Normalized In Situ by N-acetyl Cysteine Concentrations Attained in Human Cerebrospinal Fluid. Neurotherapeutics 2016; 13:217-25. [PMID: 26572666 PMCID: PMC4720670 DOI: 10.1007/s13311-015-0404-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
N-acetyl cysteine (NAC) supports the synthesis of glutathione (GSH), an essential substrate for fast, enzymatically catalyzed oxidant scavenging and protein repair processes. NAC is entering clinical trials for adrenoleukodystrophy, Parkinson's disease, schizophrenia, and other disorders in which oxidative stress may contribute to disease progression. However, these trials are hampered by uncertainty about the dose of NAC required to achieve biological effects in human brain. Here we describe an approach to this issue in which mice are used to establish the levels of NAC in cerebrospinal fluid (CSF) required to affect brain neurons. NAC dosing in humans can then be calibrated to achieve these NAC levels in human CSF. The mice were treated with NAC over a range of doses, followed by assessments of neuronal GSH levels and neuronal antioxidant capacity in ex vivo brain slices. Neuronal GSH levels and antioxidant capacity were augmented at NAC doses that produced peak CSF NAC concentrations of ≥50 nM. Oral NAC administration to humans produced CSF concentrations of up to 10 μM, thus demonstrating that oral NAC administration can surpass the levels required for biological activity in brain. Variations of this approach may similarly facilitate and rationalize drug dosing for other agents targeting central nervous system disorders.
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Affiliation(s)
- Reno C Reyes
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Giordano Fabricio Cittolin-Santos
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
- Programa de Pós Graduação em Ciências Biológicas: Bioquímica, UFRGS, Porto Alegre, Brazil
- Science Without Borders, CNPq, Brasilia, Brazil
| | - Ji-Eun Kim
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Seok Joon Won
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Angela M Brennan-Minnella
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Maya Katz
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Graham A Glass
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA
| | - Raymond A Swanson
- Neurology Service, San Francisco Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA, 94121, USA.
- The Department of Neurology, University of California, San Francisco Medical Center, San Francisco, CA, USA.
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20
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Gordon GRJ, Howarth C, MacVicar BA. Bidirectional Control of Blood Flow by Astrocytes: A Role for Tissue Oxygen and Other Metabolic Factors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:209-19. [PMID: 27343099 DOI: 10.1007/978-1-4899-7678-9_15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Altering cerebral blood flow through the control of cerebral vessel diameter is critical so that the delivery of molecules important for proper brain functioning is matched to the activity level of neurons. Although the close relationship of brain glia known as astrocytes with cerebral blood vessels has long been recognized, it is only recently that these cells have been demonstrated to translate information on the activity level and energy demands of neurons to the vasculature. In particular, astrocytes respond to elevations in extracellular glutamate as a consequence of synaptic transmission through the activation of group 1 metabotropic glutamate receptors. These Gq-protein coupled receptors elevate intracellular calcium via IP3 signaling. A close examination of astrocyte endfeet calcium signals has been shown to cause either vasoconstriction or vasodilation. Common to both vasomotor responses is the generation of arachidonic acid in astrocytes by calcium sensitive phospholipase A2. Vasoconstriction ensues from the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid, while vasodilation ensues from the production of epoxyeicosatrienoic acids or prostaglandins. Factors that determine whether constrictor or dilatory pathways predominate include brain oxygen, lactate, adenosine as well as nitric oxide. Changing the oxygen level itself leads to many downstream changes that facilitate the switch from vasoconstriction at high oxygen to vasodilation at low oxygen. These findings highlight the importance of astrocytes as sensors of neural activity and metabolism to coordinate the delivery of essential nutrients via the blood to the working cells.
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Affiliation(s)
- Grant R J Gordon
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
| | - Clare Howarth
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Brian A MacVicar
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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21
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Ayata C, Lauritzen M. Spreading Depression, Spreading Depolarizations, and the Cerebral Vasculature. Physiol Rev 2015; 95:953-93. [PMID: 26133935 DOI: 10.1152/physrev.00027.2014] [Citation(s) in RCA: 364] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Spreading depression (SD) is a transient wave of near-complete neuronal and glial depolarization associated with massive transmembrane ionic and water shifts. It is evolutionarily conserved in the central nervous systems of a wide variety of species from locust to human. The depolarization spreads slowly at a rate of only millimeters per minute by way of grey matter contiguity, irrespective of functional or vascular divisions, and lasts up to a minute in otherwise normal tissue. As such, SD is a radically different breed of electrophysiological activity compared with everyday neural activity, such as action potentials and synaptic transmission. Seventy years after its discovery by Leão, the mechanisms of SD and its profound metabolic and hemodynamic effects are still debated. What we did learn of consequence, however, is that SD plays a central role in the pathophysiology of a number of diseases including migraine, ischemic stroke, intracranial hemorrhage, and traumatic brain injury. An intriguing overlap among them is that they are all neurovascular disorders. Therefore, the interplay between neurons and vascular elements is critical for our understanding of the impact of this homeostatic breakdown in patients. The challenges of translating experimental data into human pathophysiology notwithstanding, this review provides a detailed account of bidirectional interactions between brain parenchyma and the cerebral vasculature during SD and puts this in the context of neurovascular diseases.
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Affiliation(s)
- Cenk Ayata
- Neurovascular Research Laboratory, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Neuroscience and Pharmacology and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; and Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
| | - Martin Lauritzen
- Neurovascular Research Laboratory, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Neuroscience and Pharmacology and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; and Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark
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22
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Effect of nicotinamide mononucleotide on brain mitochondrial respiratory deficits in an Alzheimer's disease-relevant murine model. BMC Neurol 2015; 15:19. [PMID: 25884176 PMCID: PMC4358858 DOI: 10.1186/s12883-015-0272-x] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 02/18/2015] [Indexed: 02/05/2023] Open
Abstract
Background Mitochondrial dysfunction is a hallmark of neurodegenerative diseases including Alzheimer’s disease (AD), with morphological and functional abnormalities limiting the electron transport chain and ATP production. A contributing factor of mitochondrial abnormalities is loss of nicotinamide adenine dinucleotide (NAD), an important cofactor in multiple metabolic reactions. Depletion of mitochondrial and consequently cellular NAD(H) levels by activated NAD glycohydrolases then culminates in bioenergetic failure and cell death. De Novo NAD+ synthesis from tryptophan requires a multi-step enzymatic reaction. Thus, an alternative strategy to maintain cellular NAD+ levels is to administer NAD+ precursors facilitating generation via a salvage pathway. We administered nicotinamide mononucleotide (NMN), an NAD+ precursor to APP(swe)/PS1(ΔE9) double transgenic (AD-Tg) mice to assess amelioration of mitochondrial respiratory deficits. In addition to mitochondrial respiratory function, we examined levels of full-length mutant APP, NAD+-dependent substrates (SIRT1 and CD38) in homogenates and fission/fusion proteins (DRP1, OPA1 and MFN2) in mitochondria isolated from brain. To examine changes in mitochondrial morphology, bigenic mice possessing a fluorescent protein targeted to neuronal mitochondria (CaMK2a-mito/eYFP), were administered NMN. Methods Mitochondrial oxygen consumption rates were examined in N2A neuroblastoma cells and non-synaptic brain mitochondria isolated from mice (3 months). Western blotting was utilized to assess APP, SIRT1, CD38, DRP1, OPA1 and MFN2 in brain of transgenic and non-transgenic mice (3–12 months). Mitochondrial morphology was assessed with confocal microscopy. One-way or two-way analysis of variance (ANOVA) and post-hoc Holm-Sidak method were used for statistical analyses of data. Student t-test was used for direct comparison of two groups. Results We now demonstrate that mitochondrial respiratory function was restored in NMN-treated AD-Tg mice. Levels of SIRT1 and CD38 change with age and NMN treatment. Furthermore, we found a shift in dynamics from fission to fusion proteins in the NMN-treated mice. Conclusions This is the first study to directly examine amelioration of NAD+ catabolism and changes in mitochondrial morphological dynamics in brain utilizing the immediate precursor NMN as a potential therapeutic compound. This might lead to well-defined physiologic abnormalities that can serve an important role in the validation of promising agents such as NMN that target NAD+ catabolism preserving mitochondrial function.
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23
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Jolivet R, Coggan JS, Allaman I, Magistretti PJ. Multi-timescale modeling of activity-dependent metabolic coupling in the neuron-glia-vasculature ensemble. PLoS Comput Biol 2015; 11:e1004036. [PMID: 25719367 PMCID: PMC4342167 DOI: 10.1371/journal.pcbi.1004036] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 11/13/2014] [Indexed: 12/21/2022] Open
Abstract
Glucose is the main energy substrate in the adult brain under normal conditions. Accumulating evidence, however, indicates that lactate produced in astrocytes (a type of glial cell) can also fuel neuronal activity. The quantitative aspects of this so-called astrocyte-neuron lactate shuttle (ANLS) are still debated. To address this question, we developed a detailed biophysical model of the brain’s metabolic interactions. Our model integrates three modeling approaches, the Buxton-Wang model of vascular dynamics, the Hodgkin-Huxley formulation of neuronal membrane excitability and a biophysical model of metabolic pathways. This approach provides a template for large-scale simulations of the neuron-glia-vasculature (NGV) ensemble, and for the first time integrates the respective timescales at which energy metabolism and neuronal excitability occur. The model is constrained by relative neuronal and astrocytic oxygen and glucose utilization, by the concentration of metabolites at rest and by the temporal dynamics of NADH upon activation. These constraints produced four observations. First, a transfer of lactate from astrocytes to neurons emerged in response to activity. Second, constrained by activity-dependent NADH transients, neuronal oxidative metabolism increased first upon activation with a subsequent delayed astrocytic glycolysis increase. Third, the model correctly predicted the dynamics of extracellular lactate and oxygen as observed in vivo in rats. Fourth, the model correctly predicted the temporal dynamics of tissue lactate, of tissue glucose and oxygen consumption, and of the BOLD signal as reported in human studies. These findings not only support the ANLS hypothesis but also provide a quantitative mathematical description of the metabolic activation in neurons and glial cells, as well as of the macroscopic measurements obtained during brain imaging. The brain has remarkable information processing capacity, yet is also very energy efficient. How this metabolic efficiency is achieved given the spatial and metabolic constraints inherent to the designs and energy requirements of brain cells is a fundamental question in neurobiology. The major cell classes in mammalian nervous systems include neurons, glia and the microvasculature that supplies the molecular substrates of energy and metabolism. Together, this neuron-glia-vasculature (NGV) ensemble constitutes the functional unit that underlies the cost infrastructure of computation. In spite of its importance, a comprehensive understanding of this dynamic system remains elusive. While it is well established that glucose feeds the brain, few of the details regarding the destiny of glucose intermediates in metabolic pathways are known. Controversy remains regarding the degree of cooperativity between glia and neurons in sharing lactate, the product of aerobic glycolysis (Warburg effect) and one of the substrates for further energy extraction by oxidative processes. Specifically, while experimental data support the occurrence of a flow of lactate from glia to neurons, the astrocyte-neuron lactate shuttle (ANLS), some theoretical considerations have been proposed to support the occurrence of lactate transport in the other direction (NALS). Our computational model is the first to integrate multiple timescales of the NGV unit. It provides a quantitative mathematical description of metabolic activation in neurons and astrocytes, and of the macroscopic measurements obtained during brain imaging that uses metabolism as a proxy for neuronal activity.
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Affiliation(s)
- Renaud Jolivet
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
- * E-mail: (RJ) (PJM)
| | - Jay S. Coggan
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- NeuroLinx Research Institute, La Jolla, California, United States of America
| | - Igor Allaman
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Pierre J. Magistretti
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
- * E-mail: (RJ) (PJM)
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Crosstalk of Signaling and Metabolism Mediated by the NAD(+)/NADH Redox State in Brain Cells. Neurochem Res 2015; 40:2394-401. [PMID: 25876186 DOI: 10.1007/s11064-015-1526-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/16/2015] [Accepted: 01/23/2015] [Indexed: 12/26/2022]
Abstract
The energy metabolism of the brain has to be precisely adjusted to activity to cope with the organ's energy demand, implying that signaling regulates metabolism and metabolic states feedback to signaling. The NAD(+)/NADH redox state constitutes a metabolic node well suited for integration of metabolic and signaling events. It is affected by flux through metabolic pathways within a cell, but also by the metabolic state of neighboring cells, for example by lactate transferred between cells. Furthermore, signaling events both in neurons and astrocytes have been reported to change the NAD(+)/NADH redox state. Vice versa, a number of signaling events like astroglial Ca(2+) signals, neuronal NMDA-receptors as well as the activity of transcription factors are modulated by the NAD(+)/NADH redox state. In this short review, this bidirectional interdependence of signaling and metabolism involving the NAD(+)/NADH redox state as well as its potential relevance for the physiology of the brain and the whole organism in respect to blood glucose regulation and body weight control are discussed.
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25
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Ivanova D, Dirks A, Montenegro-Venegas C, Schöne C, Altrock WD, Marini C, Frischknecht R, Schanze D, Zenker M, Gundelfinger ED, Fejtova A. Synaptic activity controls localization and function of CtBP1 via binding to Bassoon and Piccolo. EMBO J 2015; 34:1056-77. [PMID: 25652077 DOI: 10.15252/embj.201488796] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 01/08/2015] [Indexed: 11/09/2022] Open
Abstract
Persistent experience-driven adaptation of brain function is associated with alterations in gene expression patterns, resulting in structural and functional neuronal remodeling. How synaptic activity-in particular presynaptic performance-is coupled to gene expression in nucleus remains incompletely understood. Here, we report on a role of CtBP1, a transcriptional co-repressor enriched in presynapses and nuclei, in the activity-driven reconfiguration of gene expression in neurons. We demonstrate that presynaptic and nuclear pools of CtBP1 are interconnected and that both synaptic retention and shuttling of CtBP1 between cytoplasm and nucleus are co-regulated by neuronal activity. Finally, we show that CtBP1 is targeted and/or anchored to presynapses by direct interaction with the active zone scaffolding proteins Bassoon and Piccolo. This association is regulated by neuronal activity via modulation of cellular NAD/NADH levels and restrains the size of the CtBP1 pool available for nuclear import, thus contributing to the control of activity-dependent gene expression. Our combined results reveal a mechanism for coupling activity-induced molecular rearrangements in the presynapse with reconfiguration of neuronal gene expression.
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Affiliation(s)
- Daniela Ivanova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Research Group Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anika Dirks
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | | - Cornelia Schöne
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Wilko D Altrock
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
| | - Claudia Marini
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Renato Frischknecht
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
| | - Denny Schanze
- Institute for Human Genetics, Otto von Guericke University, Magdeburg, Germany
| | - Martin Zenker
- Institute for Human Genetics, Otto von Guericke University, Magdeburg, Germany
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany Molecular Neurobiology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Research Group Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
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26
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PARP1 activation/expression modulates regional-specific neuronal and glial responses to seizure in a hemodynamic-independent manner. Cell Death Dis 2014; 5:e1362. [PMID: 25101675 PMCID: PMC4454306 DOI: 10.1038/cddis.2014.331] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/10/2014] [Accepted: 07/03/2014] [Indexed: 11/08/2022]
Abstract
Poly(ADP-ribose) polymerase-1 (PARP1) plays a regulatory role in apoptosis, necrosis and other cellular processes after injury. Status epilepticus (SE) induces neuronal and astroglial death that show regional-specific patterns in the rat hippocampus and piriform cortex (PC). Thus, we investigated whether PARP1 regulates the differential neuronal/glial responses to pilocarpine (PILO)-induced SE in the distinct brain regions. In the present study, both CA1 and CA3 neurons showed PARP1 hyperactivation-dependent neuronal death pathway, whereas PC neurons exhibited PARP1 degradation-mediated neurodegeneration following SE. PARP1 degradation was also observed in astrocytes within the molecular layer of the dentate gyrus. PARP1 induction was detected in CA1-3-reactive astrocytes, as well as in reactive microglia within the PC. Although PARP1 inhibitors attenuated CA1-3 neuronal death and reactive gliosis in the CA1 region, they deteriorated the astroglial death in the molecular layer of the dentate gyrus and in the stratum lucidum of the CA3 region. Ex vivo study showed the similar regional and cellular patterns of PARP1 activation/degradation. Taken together, our findings suggest that the cellular-specific PARP1 activation/degradation may distinctly involve regional-specific neuronal damage, astroglial death and reactive gliosis in response to SE independently of hemodynamics.
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Highly energized inhibitory interneurons are a central element for information processing in cortical networks. J Cereb Blood Flow Metab 2014; 34:1270-82. [PMID: 24896567 PMCID: PMC4126088 DOI: 10.1038/jcbfm.2014.104] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/09/2014] [Accepted: 05/21/2014] [Indexed: 01/09/2023]
Abstract
Gamma oscillations (∼30 to 100 Hz) provide a fundamental mechanism of information processing during sensory perception, motor behavior, and memory formation by coordination of neuronal activity in networks of the hippocampus and neocortex. We review the cellular mechanisms of gamma oscillations about the underlying neuroenergetics, i.e., high oxygen consumption rate and exquisite sensitivity to metabolic stress during hypoxia or poisoning of mitochondrial oxidative phosphorylation. Gamma oscillations emerge from the precise synaptic interactions of excitatory pyramidal cells and inhibitory GABAergic interneurons. In particular, specialized interneurons such as parvalbumin-positive basket cells generate action potentials at high frequency ('fast-spiking') and synchronize the activity of numerous pyramidal cells by rhythmic inhibition ('clockwork'). As prerequisites, fast-spiking interneurons have unique electrophysiological properties and particularly high energy utilization, which is reflected in the ultrastructure by enrichment with mitochondria and cytochrome c oxidase, most likely needed for extensive membrane ion transport and γ-aminobutyric acid metabolism. This supports the hypothesis that highly energized fast-spiking interneurons are a central element for cortical information processing and may be critical for cognitive decline when energy supply becomes limited ('interneuron energy hypothesis'). As a clinical perspective, we discuss the functional consequences of metabolic and oxidative stress in fast-spiking interneurons in aging, ischemia, Alzheimer's disease, and schizophrenia.
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San Martín A, Sotelo-Hitschfeld T, Lerchundi R, Fernández-Moncada I, Ceballo S, Valdebenito R, Baeza-Lehnert F, Alegría K, Contreras-Baeza Y, Garrido-Gerter P, Romero-Gómez I, Barros LF. Single-cell imaging tools for brain energy metabolism: a review. NEUROPHOTONICS 2014; 1:011004. [PMID: 26157964 PMCID: PMC4478754 DOI: 10.1117/1.nph.1.1.011004] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 04/09/2014] [Accepted: 04/10/2014] [Indexed: 05/03/2023]
Abstract
Neurophotonics comes to light at a time in which advances in microscopy and improved calcium reporters are paving the way toward high-resolution functional mapping of the brain. This review relates to a parallel revolution in metabolism. We argue that metabolism needs to be approached both in vitro and in vivo, and that it does not just exist as a low-level platform but is also a relevant player in information processing. In recent years, genetically encoded fluorescent nanosensors have been introduced to measure glucose, glutamate, ATP, NADH, lactate, and pyruvate in mammalian cells. Reporting relative metabolite levels, absolute concentrations, and metabolic fluxes, these sensors are instrumental for the discovery of new molecular mechanisms. Sensors continue to be developed, which together with a continued improvement in protein expression strategies and new imaging technologies, herald an exciting era of high-resolution characterization of metabolism in the brain and other organs.
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Affiliation(s)
- Alejandro San Martín
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Tamara Sotelo-Hitschfeld
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Rodrigo Lerchundi
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Ignacio Fernández-Moncada
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Sebastian Ceballo
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
| | - Rocío Valdebenito
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
| | | | - Karin Alegría
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
| | - Yasna Contreras-Baeza
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Pamela Garrido-Gerter
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Ignacio Romero-Gómez
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - L. Felipe Barros
- Centro de Estudios Científicos, Arturo Prat 514, Valdivia, 5110466, Chile
- Address all correspondence to: L. Felipe Barros, E-mail:
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29
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Glycolysis and oxidative phosphorylation in neurons and astrocytes during network activity in hippocampal slices. J Cereb Blood Flow Metab 2014; 34:397-407. [PMID: 24326389 PMCID: PMC3948126 DOI: 10.1038/jcbfm.2013.222] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 12/14/2022]
Abstract
Network activation triggers a significant energy metabolism increase in both neurons and astrocytes. Questions of the primary neuronal energy substrate (e.g., glucose vs. lactate) as well as the relative contributions of glycolysis and oxidative phosphorylation and their cellular origin (neurons vs. astrocytes) are still a matter of debates. Using simultaneous measurements of electrophysiological and metabolic parameters during synaptic stimulation in hippocampal slices from mature mice, we show that neurons and astrocytes use both glycolysis and oxidative phosphorylation to meet their energy demands. Supplementation or replacement of glucose in artificial cerebrospinal fluid (ACSF) with pyruvate or lactate strongly modifies parameters related to network activity-triggered energy metabolism. These effects are not induced by changes in ATP content, pH(i), [Ca(2+)](i) or accumulation of reactive oxygen species. Our results suggest that during network activation, a significant fraction of NAD(P)H response (its overshoot phase) corresponds to glycolysis and the changes in cytosolic NAD(P)H and mitochondrial FAD are coupled. Our data do not support the hypothesis of a preferential utilization of astrocyte-released lactate by neurons during network activation in slices--instead, we show that during such activity glucose is an effective energy substrate for both neurons and astrocytes.
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30
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San Martín A, Ceballo S, Baeza-Lehnert F, Lerchundi R, Valdebenito R, Contreras-Baeza Y, Alegría K, Barros LF. Imaging mitochondrial flux in single cells with a FRET sensor for pyruvate. PLoS One 2014; 9:e85780. [PMID: 24465702 PMCID: PMC3897509 DOI: 10.1371/journal.pone.0085780] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 12/05/2013] [Indexed: 11/24/2022] Open
Abstract
Mitochondrial flux is currently accessible at low resolution. Here we introduce a genetically-encoded FRET sensor for pyruvate, and methods for quantitative measurement of pyruvate transport, pyruvate production and mitochondrial pyruvate consumption in intact individual cells at high temporal resolution. In HEK293 cells, neurons and astrocytes, mitochondrial pyruvate uptake was saturated at physiological levels, showing that the metabolic rate is determined by intrinsic properties of the organelle and not by substrate availability. The potential of the sensor was further demonstrated in neurons, where mitochondrial flux was found to rise by 300% within seconds of a calcium transient triggered by a short theta burst, while glucose levels remained unaltered. In contrast, astrocytic mitochondria were insensitive to a similar calcium transient elicited by extracellular ATP. We expect the improved resolution provided by the pyruvate sensor will be of practical interest for basic and applied researchers interested in mitochondrial function.
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Affiliation(s)
- Alejandro San Martín
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | | | | | - Rodrigo Lerchundi
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | | | - Yasna Contreras-Baeza
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Karin Alegría
- Centro de Estudios Científicos (CECs), Valdivia, Chile
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Otáhal J, Folbergrová J, Kovacs R, Kunz WS, Maggio N. Epileptic focus and alteration of metabolism. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 114:209-43. [PMID: 25078504 DOI: 10.1016/b978-0-12-418693-4.00009-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Epilepsy is one of the most common neurologic disorders affecting a substantial part of the population worldwide. Epileptic seizures represent the situation of increased neuronal activity associated with the enhanced demands for sufficient energy supply. For that purpose, very efficient regulatory mechanisms have to operate to ensure that cerebral blood flow, delivery of oxygen, and nutrients are continuously adapted to the local metabolic needs. The sophisticated regulation has to function in concert at several levels (systemic, tissue, cellular, and subcellular). Particularly, mitochondria play a key role not only in the energy production, but they are also central to many other processes including those leading to neuronal death. Impairment of any of the involved pathways can result in serious functional alterations, neurodegeneration, and potentially in epileptogenesis. The present review will address some of the important issues concerning vascular and metabolic changes in pathophysiology of epilepsy.
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Affiliation(s)
- Jakub Otáhal
- Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | - Jaroslava Folbergrová
- Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Richard Kovacs
- Institute for Neurophysiology, Charité-Medical University Berlin, Berlin, Germany
| | - Wolfram S Kunz
- Department of Epileptology, University of Bonn, Bonn, Germany
| | - Nicola Maggio
- Department of Neurology, The Joseph Sagol Neuroscience Center, The Chaim Sheba Medical Center, Tel HaShomer, Israel; Talpiot Medical Leadership Program, The Chaim Sheba Medical Center, Tel HaShomer, Israel
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Bouzier-Sore AK, Pellerin L. Unraveling the complex metabolic nature of astrocytes. Front Cell Neurosci 2013; 7:179. [PMID: 24130515 PMCID: PMC3795301 DOI: 10.3389/fncel.2013.00179] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/23/2013] [Indexed: 12/12/2022] Open
Abstract
Since the initial description of astrocytes by neuroanatomists of the nineteenth century, a critical metabolic role for these cells has been suggested in the central nervous system. Nonetheless, it took several technological and conceptual advances over many years before we could start to understand how they fulfill such a role. One of the important and early recognized metabolic function of astrocytes concerns the reuptake and recycling of the neurotransmitter glutamate. But the description of this initial property will be followed by several others including an implication in the supply of energetic substrates to neurons. Indeed, despite the fact that like most eukaryotic non-proliferative cells, astrocytes rely on oxidative metabolism for energy production, they exhibit a prominent aerobic glycolysis capacity. Moreover, this unusual metabolic feature was found to be modulated by glutamatergic activity constituting the initial step of the neurometabolic coupling mechanism. Several approaches, including biochemical measurements in cultured cells, genetic screening, dynamic cell imaging, nuclear magnetic resonance spectroscopy and mathematical modeling, have provided further insights into the intrinsic characteristics giving rise to these key features of astrocytes. This review will provide an account of the different results obtained over several decades that contributed to unravel the complex metabolic nature of astrocytes that make this cell type unique.
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Affiliation(s)
- Anne-Karine Bouzier-Sore
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS/Université Bordeaux Segalen Bordeaux, France
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33
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Metabolic signaling by lactate in the brain. Trends Neurosci 2013; 36:396-404. [DOI: 10.1016/j.tins.2013.04.002] [Citation(s) in RCA: 220] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/31/2013] [Accepted: 04/01/2013] [Indexed: 01/27/2023]
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Grasselli G, Rossi S, Musella A, Gentile A, Loizzo S, Muzio L, Di Sanza C, Errico F, Musumeci G, Haji N, Fresegna D, Sepman H, De Chiara V, Furlan R, Martino G, Usiello A, Mandolesi G, Centonze D. Abnormal NMDA receptor function exacerbates experimental autoimmune encephalomyelitis. Br J Pharmacol 2013; 168:502-17. [PMID: 22924679 DOI: 10.1111/j.1476-5381.2012.02178.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 08/04/2012] [Accepted: 08/13/2012] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Glutamate transmission is dysregulated in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), the animal model of MS. A characteristic of EAE is increased glutamate transmission associated with up-regulation of AMPA receptors. However, little is known about the role of NMDA receptors in the synaptic modifications induced by EAE. EXPERIMENTAL APPROACH The contribution of NMDA receptors to the alterations of glutamate transmission and disease severity in EAE mice was assessed by means of neurophysiological, morphological, Western blot, metabolic and clinical score assessments. KEY RESULTS In our EAE mice, there was an NMDA receptor-dependent increase of glutamate release, associated with marked activation of the astroglia. Presynaptic NMDA receptors became overactive during EAE, increasing synaptic glutamate release by a mechanism dependent on voltage-gated sodium channels. By means of NAD(P)H autofluorescence analysis, we also found that EAE has a glutamate and NMDA receptor-dependent dysfunction of mitochondrial activity, which is known to contribute to the neurodegenerative damage of MS and EAE. Furthermore, pharmacological blockade of NMDA receptors in vivo ameliorated both synaptic transmission defects and of the clinical disease course of EAE mice, while EAE induced in mice with a genetically enhanced NMDA receptor signalling had opposite effects. CONCLUSIONS AND IMPLICATIONS Our data, showing both sensitization of NMDA receptors and their involvement in the progression of the EAE disease, supggest that pharmacological impairment of NMDA receptor signalling would be a component of a neuroprotection strategy in MS.
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Affiliation(s)
- G Grasselli
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Università Tor Vergata, Rome, Italy
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35
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Abstract
Neuronal computation is energetically expensive. Consequently, the brain's limited energy supply imposes constraints on its information processing capability. Most brain energy is used on synaptic transmission, making it important to understand how energy is provided to and used by synapses. We describe how information transmission through presynaptic terminals and postsynaptic spines is related to their energy consumption, assess which mechanisms normally ensure an adequate supply of ATP to these structures, consider the influence of synaptic plasticity and changing brain state on synaptic energy use, and explain how disruption of the energy supply to synapses leads to neuropathology.
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Affiliation(s)
- Julia J Harris
- Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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36
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Abstract
Neuroenergetic models of synaptic transmission predicted that energy demand is highest for action potentials (APs) and postsynaptic ion fluxes, whereas the presynaptic contribution is rather small. Here, we addressed the question of energy consumption at Schaffer-collateral synapses. We monitored stimulus-induced changes in extracellular potassium, sodium, and calcium concentration while recording partial oxygen pressure (pO(2)) and NAD(P)H fluorescence. Blockade of postsynaptic receptors reduced ion fluxes as well as pO(2) and NAD(P)H transients by ∼50%. Additional blockade of transmitter release further reduced Na(+), K(+), and pO(2) transients by ∼30% without altering presynaptic APs, indicating considerable contribution of Ca(2+)-removal, transmitter and vesicle turnover to energy consumption.
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37
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Oxidative phosphorylation, not glycolysis, powers presynaptic and postsynaptic mechanisms underlying brain information processing. J Neurosci 2012; 32:8940-51. [PMID: 22745494 DOI: 10.1523/jneurosci.0026-12.2012] [Citation(s) in RCA: 298] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neural activity has been suggested to initially trigger ATP production by glycolysis, rather than oxidative phosphorylation, for three reasons: glycolytic enzymes are associated with ion pumps; neurons may increase their energy supply by activating glycolysis in astrocytes to generate lactate; and activity increases glucose uptake more than O₂ uptake. In rat hippocampal slices, neuronal activity rapidly decreased the levels of extracellular O₂ and intracellular NADH (reduced nicotinamide adenine dinucleotide), even with lactate dehydrogenase blocked to prevent lactate generation, or with only 20% superfused O₂ to mimic physiological O₂ levels. Pharmacological analysis revealed an energy budget in which 11% of O₂ use was on presynaptic action potentials, 17% was on presynaptic Ca²⁺ entry and transmitter release, 46% was on postsynaptic glutamate receptors, and 26% was on postsynaptic action potentials, in approximate accord with theoretical brain energy budgets. Thus, the major mechanisms mediating brain information processing are all initially powered by oxidative phosphorylation, and an astrocyte-neuron lactate shuttle is not needed for this to occur.
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Abstract
Potential roles for lactate in the energetics of brain activation have changed radically during the past three decades, shifting from waste product to supplemental fuel and signaling molecule. Current models for lactate transport and metabolism involving cellular responses to excitatory neurotransmission are highly debated, owing, in part, to discordant results obtained in different experimental systems and conditions. Major conclusions drawn from tabular data summarizing results obtained in many laboratories are as follows: Glutamate-stimulated glycolysis is not an inherent property of all astrocyte cultures. Synaptosomes from the adult brain and many preparations of cultured neurons have high capacities to increase glucose transport, glycolysis, and glucose-supported respiration, and pathway rates are stimulated by glutamate and compounds that enhance metabolic demand. Lactate accumulation in activated tissue is a minor fraction of glucose metabolized and does not reflect pathway fluxes. Brain activation in subjects with low plasma lactate causes outward, brain-to-blood lactate gradients, and lactate is quickly released in substantial amounts. Lactate utilization by the adult brain increases during lactate infusions and strenuous exercise that markedly increase blood lactate levels. Lactate can be an 'opportunistic', glucose-sparing substrate when present in high amounts, but most evidence supports glucose as the major fuel for normal, activated brain.
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Schurr A, Gozal E. Aerobic production and utilization of lactate satisfy increased energy demands upon neuronal activation in hippocampal slices and provide neuroprotection against oxidative stress. Front Pharmacol 2012; 2:96. [PMID: 22275901 PMCID: PMC3257848 DOI: 10.3389/fphar.2011.00096] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/23/2011] [Indexed: 12/21/2022] Open
Abstract
Ever since it was shown for the first time that lactate can support neuronal function in vitro as a sole oxidative energy substrate, investigators in the field of neuroenergetics have been debating the role, if any, of this glycolytic product in cerebral energy metabolism. Our experiments employed the rat hippocampal slice preparation with electrophysiological and biochemical methodologies. The data generated by these experiments (a) support the hypothesis that lactate, not pyruvate, is the end-product of cerebral aerobic glycolysis; (b) indicate that lactate plays a major and crucial role in affording neural tissue to respond adequately to glutamate excitation and to recover unscathed post-excitation; (c) suggest that neural tissue activation is accompanied by aerobic lactate and NADH production, the latter being produced when the former is converted to pyruvate by mitochondrial lactate dehydrogenase (mLDH); (d) imply that NADH can be utilized as an endogenous scavenger of reactive oxygen species (ROS) to provide neuroprotection against ROS-induced neuronal damage.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville Louisville, KY, USA.
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Kann O. The energy demand of fast neuronal network oscillations: insights from brain slice preparations. Front Pharmacol 2012; 2:90. [PMID: 22291647 PMCID: PMC3254178 DOI: 10.3389/fphar.2011.00090] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 12/20/2011] [Indexed: 01/09/2023] Open
Abstract
Fast neuronal network oscillations in the gamma range (30-100 Hz) in the cerebral cortex have been implicated in higher cognitive functions such as sensual perception, working memory, and, perhaps, consciousness. However, little is known about the energy demand of gamma oscillations. This is mainly caused by technical limitations that are associated with simultaneous recordings of neuronal activity and energy metabolism in small neuronal networks and at the level of mitochondria in vivo. Thus recent studies have focused on brain slice preparations to address the energy demand of gamma oscillations in vitro. Here, reports will be summarized and discussed that combined electrophysiological recordings, oxygen sensor microelectrodes, and live-cell fluorescence imaging in acutely prepared slices and organotypic slice cultures of the hippocampus from both, mouse and rat. These reports consistently show that gamma oscillations can be reliably induced in hippocampal slice preparations by different pharmacological tools. They suggest that gamma oscillations are associated with high energy demand, requiring both rapid adaptation of oxidative energy metabolism and sufficient supply with oxygen and nutrients. These findings might help to explain the exceptional vulnerability of higher cognitive functions during pathological processes of the brain, such as circulatory disturbances, genetic mitochondrial diseases, and neurodegeneration.
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Affiliation(s)
- Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany. oliver.kann@physiologie
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Kann O, Taubenberger N, Huchzermeyer C, Papageorgiou IE, Benninger F, Heinemann U, Kovács R. Muscarinic receptor activation determines the effects of store-operated Ca2+-entry on excitability and energy metabolism in pyramidal neurons. Cell Calcium 2012; 51:40-50. [DOI: 10.1016/j.ceca.2011.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/14/2011] [Accepted: 10/19/2011] [Indexed: 10/15/2022]
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Bi J, Li H, Ye SQ, Ding S. Pre-B-cell colony-enhancing factor exerts a neuronal protection through its enzymatic activity and the reduction of mitochondrial dysfunction in in vitro ischemic models. J Neurochem 2011; 120:334-46. [PMID: 22044451 DOI: 10.1111/j.1471-4159.2011.07566.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Pre-B-cell colony-enhancing factor (PBEF) is known as a rate-limiting enzyme that converts nicotinamide (NAM) to NMN in the salvage pathway of mammalian NAD⁺ biosynthesis. Previously we found PBEF is exclusively expressed in neurons in the mouse brain; heterozygous PBEF knockout (Pbef⁺/⁻) mice have larger ischemic lesion than wild type mice in photothrombosis-induced ischemia. For the mechanistic study of neuronal protective role of PBEF, we used in vitro oxygen-glucose deprivation (OGD) and glutamate excitotoxicity models of primary cultured neurons in current study. Our results showed that the treatments of neurons with NAM and NAD⁺, the substrate and downstream product of PBEF, respectively, significantly reduced neuronal death after OGD and glutamate excitotoxicity, while treatment of neurons treated with FK866, a PBEF inhibitor, increased neuronal death after OGD. Furthermore, over-expression of human PBEF reduced glutamate excitotoxicity, while over-expression of human PBEF mutants (i.e. H247A and H247E) without enzymatic activity had no effect on neuronal death. We further tested the effect of PBEF on mitochondrial function and biogenesis. Our results show that addition of NAD⁺ and NAM increased mitochondrial biogenesis in neurons after OGD. Over-expression of PBEF in neurons reduced mitochondrial membrane potential depolarization following glutamate stimulation, while over-expression of H247A and H247E did not affect mitochondrial membrane potential depolarization. We conclude that PBEF has a neuroprotective effect in ischemia through its enzymatic activity for NAD⁺ production that can ameliorate mitochondrial dysfunction.
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Affiliation(s)
- Jing Bi
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Missouri 65211, USA
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Reinert KC, Gao W, Chen G, Wang X, Peng YP, Ebner TJ. Cellular and metabolic origins of flavoprotein autofluorescence in the cerebellar cortex in vivo. CEREBELLUM (LONDON, ENGLAND) 2011; 10:585-99. [PMID: 21503591 PMCID: PMC4126810 DOI: 10.1007/s12311-011-0278-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Flavoprotein autofluorescence imaging, an intrinsic mitochondrial signal, has proven useful for monitoring neuronal activity. In the cerebellar cortex, parallel fiber stimulation evokes a beam-like response consisting of an initial, short-duration increase in fluorescence (on-beam light phase) followed by a longer duration decrease (on-beam dark phase). Also evoked are parasagittal bands of decreased fluorescence due to molecular layer inhibition. Previous work suggests that the on-beam light phase is due to oxidative metabolism in neurons. The present study further investigated the metabolic and cellular origins of the flavoprotein signal in vivo, testing the hypotheses that the dark phase is mediated by glia activation and the inhibitory bands reflect decreased flavoprotein oxidation and increased glycolysis in neurons. Blocking postsynaptic ionotropic and metabotropic glutamate receptors abolished the on-beam light phase and the parasagittal bands without altering the on-beam dark phase. Adding glutamate transporter blockers reduced the dark phase. Replacing glucose with lactate (or pyruvate) or adding lactate to the bathing media abolished the on-beam dark phase and reduced the inhibitory bands without affecting the light phase. Blocking monocarboxylate transporters eliminated the on-beam dark phase and increased the light phase. These results confirm that the on-beam light phase is due primarily to increased oxidative metabolism in neurons. They also show that the on-beam dark phase involves activation of glycolysis in glia resulting in the generation of lactate that is transferred to neurons. Oxidative savings in neurons contributes to the decrease in fluorescence characterizing the inhibitory bands. These findings provide strong in vivo support for the astrocyte-neuron lactate shuttle hypothesis.
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Affiliation(s)
- Kenneth C. Reinert
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Wangcai Gao
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth St. S.E., Minneapolis, MN 55455, USA
| | - Gang Chen
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth St. S.E., Minneapolis, MN 55455, USA
| | - Xinming Wang
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth St. S.E., Minneapolis, MN 55455, USA
| | - Yu-Ping Peng
- Nantong University, Nantong, Jiangsu 226001, People’s Republic of China
| | - Timothy J. Ebner
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth St. S.E., Minneapolis, MN 55455, USA,
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Porras OH, Stutzin A. Glutamate-induced metabolic changes influence the cytoplasmic redox state of hippocampal neurons. Biochem Biophys Res Commun 2011; 411:82-7. [DOI: 10.1016/j.bbrc.2011.06.097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 06/12/2011] [Indexed: 10/18/2022]
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Kasischke K. Lactate fuels the neonatal brain. FRONTIERS IN NEUROENERGETICS 2011; 3:4. [PMID: 21687795 PMCID: PMC3108381 DOI: 10.3389/fnene.2011.00004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 05/20/2011] [Indexed: 11/13/2022]
Affiliation(s)
- Karl Kasischke
- Department of Neurology, Center for Neural Development and Disease, University of Rochester Medical Center Rochester, NY, USA
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Ivanov A, Mukhtarov M, Bregestovski P, Zilberter Y. Lactate Effectively Covers Energy Demands during Neuronal Network Activity in Neonatal Hippocampal Slices. FRONTIERS IN NEUROENERGETICS 2011; 3:2. [PMID: 21602909 PMCID: PMC3092068 DOI: 10.3389/fnene.2011.00002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/25/2011] [Indexed: 11/13/2022]
Abstract
Although numerous experimental data indicate that lactate is efficiently used for energy by the mature brain, the direct measurements of energy metabolism parameters during neuronal network activity in early postnatal development have not been performed. Therefore, the role of lactate in the energy metabolism of neurons at this age remains unclear. In this study, we monitored field potentials and contents of oxygen and NAD(P)H in correlation with oxidative metabolism during intense network activity in the CA1 hippocampal region of neonatal brain slices. We show that in the presence of glucose, lactate is effectively utilized as an energy substrate, causing an augmentation of oxidative metabolism. Moreover, in the absence of glucose lactate is fully capable of maintaining synaptic function. Therefore, during network activity in neonatal slices, lactate can be an efficient energy substrate capable of sustaining and enhancing aerobic energy metabolism.
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Affiliation(s)
- Anton Ivanov
- Faculté de Médecine Timone, Institut National de la Santé et de la Recherche Médicale U751, Université de la Méditerranée Marseille, France
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Kristian T, Balan I, Schuh R, Onken M. Mitochondrial dysfunction and nicotinamide dinucleotide catabolism as mechanisms of cell death and promising targets for neuroprotection. J Neurosci Res 2011; 89:1946-55. [PMID: 21488086 DOI: 10.1002/jnr.22626] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 01/07/2011] [Accepted: 01/17/2011] [Indexed: 11/12/2022]
Abstract
Both acute and chronic neurodegenerative diseases are frequently associated with mitochondrial dysfunction as an essential component of mechanisms leading to brain damage. Although loss of mitochondrial functions resulting from prolonged activation of the mitochondrial permeability transition (MPT) pore has been shown to play a significant role in perturbation of cellular bioenergetics and in cell death, the detailed mechanisms are still elusive. Enzymatic reactions linked to glycolysis, the tricarboxylic acid cycle, and mitochondrial respiration are dependent on the reduced or oxidized form of nicotinamide dinucleotide [NAD(H)] as a cofactor. Loss of mitochondrial NAD(+) resulting from MPT pore opening, although transient, allows detrimental depletion of mitochondrial and cellular NAD(+) pools by activated NAD(+) glycohydrolases. Poly(ADP-ribose) polymerase (PARP) is considered to be a major NAD(+) degrading enzyme, particularly under conditions of extensive DNA damage. We propose that CD38, a main cellular NAD(+) level regulator, can significantly contribute to NAD(+) catabolism. We discuss NAD(+) catabolic and NAD(+) synthesis pathways and their role in different strategies to prevent cellular NAD(+) degradation in brain, particularly following an ischemic insult. These therapeutic approaches are based on utilizing endogenous intermediates of NAD(+) metabolism that feed into the NAD(+) salvage pathway and also inhibit CD38 activity.
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Affiliation(s)
- Tibor Kristian
- Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland 21201, USA.
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Figley CR, Stroman PW. The role(s) of astrocytes and astrocyte activity in neurometabolism, neurovascular coupling, and the production of functional neuroimaging signals. Eur J Neurosci 2011; 33:577-88. [DOI: 10.1111/j.1460-9568.2010.07584.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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49
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Wang X, Chen G, Gao W, Ebner TJ. Parasagittally aligned, mGluR1-dependent patches are evoked at long latencies by parallel fiber stimulation in the mouse cerebellar cortex in vivo. J Neurophysiol 2011; 105:1732-46. [PMID: 21289138 DOI: 10.1152/jn.00717.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The parallel fibers (PFs) in the cerebellar cortex extend several millimeters along a folium in the mediolateral direction. The PFs are orthogonal to and cross several parasagittal zones defined by the olivocerebellar and corticonuclear pathways and the expression of molecular markers on Purkinje cells (PCs). The functions of these two organizations remain unclear, including whether the bands respond similarly or differentially to PF input. By using flavoprotein imaging in the anesthetized mouse in vivo, this study demonstrates that high-frequency PF stimulation, which activates a beamlike response at short latency, also evokes patches of activation at long latencies. These patches consist of increased fluorescence along the beam at latencies of 20-25 s with peak activation at 35 s. The long-latency patches are completely blocked by the type 1 metabotropic glutamate receptor (mGluR(1)) antagonist LY367385. Conversely, the AMPA and NMDA glutamate receptor antagonists DNQX and APV have little effect. Organized in parasagittal bands, the long-latency patches align with zebrin II-positive PC stripes. Additional Ca(2+) imaging demonstrates that the patches reflect increases in intracellular Ca(2+). Both the PLCβ inhibitor U73122 and the ryanodine receptor inhibitor ryanodine completely block the long-latency patches, indicating that the patches are due to Ca(2+) release from intracellular stores. Robust, mGluR(1)-dependent long-term potentiation (LTP) of the patches is induced using a high-frequency PF stimulation conditioning paradigm that generates LTP of PF-PC synapses. Therefore, the parasagittal bands, as defined by the molecular compartmentalization of PCs, respond differentially to PF inputs via mGluR(1)-mediated release of internal Ca(2+).
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Affiliation(s)
- Xinming Wang
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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50
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Mukhtarov M, Ivanov A, Zilberter Y, Bregestovski P. Inhibition of spontaneous network activity in neonatal hippocampal slices by energy substrates is not correlated with intracellular acidification. J Neurochem 2011; 116:316-21. [PMID: 21083663 DOI: 10.1111/j.1471-4159.2010.07111.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several energy substrates complementary to glucose, including lactate, pyruvate and β-hydroxybutyrate, serve as a fuel for neurons. It was reported recently that these substrates can substantially modulate cortical excitability in neonatal slices. However, complementary energy substrates (CES) can also induce an intracellular acidification when added exogenously. Therefore, action of CES on the neuronal properties governing excitability in neonatal brain slices may be underlain by a change in the cell energy status or by intracellular acidification, or both. Here, we attempt to elucidate these possibilities in neonatal hippocampus by recording neuronal population activity and monitoring intracellular pH. We show that a spontaneous network activity pattern, giant depolarizing potentials (GDPs), characteristic for the neonatal hippocampal slices exposed to artificial cerebrospinal fluid, is strongly inhibited by CES and this effect is unlikely to be caused by a subtle intracellular acidification induced by these compounds. Indeed, a much stronger intracellular acidification in the HCO(3) -free solution inhibited neither the GDP frequency nor the GDP amplitude. Therefore, modulation of neuronal energy homeostasis is the most likely factor underlying the effect of lactate, pyruvate and β-hydroxybutyrate on network excitability in neonatal brain slices.
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Affiliation(s)
- Marat Mukhtarov
- INSERM-U901, Université de la Méditerranée, Marseille, France
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