151
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Delezie J, Handschin C. Endocrine Crosstalk Between Skeletal Muscle and the Brain. Front Neurol 2018; 9:698. [PMID: 30197620 PMCID: PMC6117390 DOI: 10.3389/fneur.2018.00698] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 08/02/2018] [Indexed: 12/22/2022] Open
Abstract
Skeletal muscle is an essential regulator of energy homeostasis and a potent coordinator of exercise-induced adaptations in other organs including the liver, fat or the brain. Skeletal muscle-initiated crosstalk with other tissues is accomplished though the secretion of myokines, protein hormones which can exert autocrine, paracrine and long-distance endocrine effects. In addition, the enhanced release or uptake of metabolites from and into contracting muscle cells, respectively, likewise can act as a powerful mediator of tissue interactions, in particular in regard to the central nervous system. The present review will discuss the current stage of knowledge regarding how exercise and the muscle secretome improve a broad range of brain functions related to vascularization, neuroplasticity, memory, sleep and mood. Even though the molecular and cellular mechanisms underlying the communication between muscle and brain is still poorly understood, physical activity represents one of the most effective strategies to reduce the prevalence and incidence of depression, cognitive, metabolic or degenerative neuronal disorders, and thus warrants further study.
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152
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Zorec R, Županc TA, Verkhratsky A. Astrogliopathology in the infectious insults of the brain. Neurosci Lett 2018; 689:56-62. [PMID: 30096375 DOI: 10.1016/j.neulet.2018.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 08/03/2018] [Accepted: 08/04/2018] [Indexed: 12/28/2022]
Abstract
Astroglia, a heterogeneous type of neuroglia, play key homeostatic functions in the central nervous system (CNS) and represent an important defence system. Impaired homeostatic capacity of astrocytes manifests in diseases and this is mirrored in various astrocyte-based pathological features including reactive astrogliosis, astrodegeneration with astroglial atrophy and pathological remodelling of astrocytes. All of these manifestations are most prominently associated with infectious insults, mediated by bacteria, protozoa and viruses. Here we focus onto neurotropic viruses such as tick-borne encephalitis (TBEV) and Zika virus (ZIKV), both belonging to Flaviviridae and both causing severe neurological impairments. We argue that astrocytes provide a route through which neurotropic infectious agents attack the CNS, since they are anatomically associated with the blood-brain barrier and exhibit aerobic glycolysis, a metabolic specialisation of highly morphologically dynamic cells, which may provide a suitable metabolic milieu for proliferation of infectious agents, including viral bodies.
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Affiliation(s)
- Robert Zorec
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000, Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia
| | - Tatjana Avšič Županc
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
| | - Alexei Verkhratsky
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000, Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
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153
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Hosford PS, Mosienko V, Kishi K, Jurisic G, Seuwen K, Kinzel B, Ludwig MG, Wells JA, Christie IN, Koolen L, Abdala AP, Liu BH, Gourine AV, Teschemacher AG, Kasparov S. CNS distribution, signalling properties and central effects of G-protein coupled receptor 4. Neuropharmacology 2018; 138:381-392. [PMID: 29894771 PMCID: PMC6063991 DOI: 10.1016/j.neuropharm.2018.06.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 12/14/2022]
Abstract
Information on the distribution and biology of the G-protein coupled receptor 4 (GPR4) in the brain is limited. It is currently thought that GPR4 couples to Gs proteins and may mediate central respiratory sensitivity to CO2. Using a knock-in mouse model, abundant GPR4 expression was detected in the cerebrovascular endothelium and neurones of dorsal raphe, retro-trapezoidal nucleus locus coeruleus and lateral septum. A similar distribution was confirmed using RNAscope in situ hybridisation. In HEK293 cells, overexpressing GPR4, it was highly constitutively active at neutral pH with little further increase in cAMP towards acidic pH. The GPR4 antagonist NE 52-QQ57 effectively blocked GPR4-mediated cAMP accumulation (IC50 26.8 nM in HEK293 cells). In HUVEC which natively express GPR4, physiological acidification (pH 7.4-7.0) resulted in a cAMP increase by ∼55% which was completely prevented by 1 μM NE 52-QQ57. The main extracellular organic acid, l-lactic acid (LL; 1-10 mM), suppressed pH dependent activation of GPR4 in HEK293 and HUVEC cells, suggesting allosteric negative modulation. In unanaesthetised mice and rats, NE 52-QQ57 (20 mg kg-1) reduced ventilatory response to 5 and 10% CO2. In anaesthetised rats, systemic administration of NE 52-QQ57 (up to 20 mg kg-1) had no effect on hemodynamics, cerebral blood flow and blood oxygen level dependent responses. Central administration of NE 52-QQ57 (1 mM) in vagotomised anaesthetised rats did not affect CO2-induced respiratory responses. Our results indicate that GPR4 is expressed by multiple neuronal populations and endothelium and that its pH sensitivity is affected by level of expression and LL. NE 52-QQ57 blunts hypercapnic response to CO2 but this effect is absent under anaesthesia, possibly due to the inhibitory effect of LL on GPR4.
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Affiliation(s)
- P S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - V Mosienko
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - K Kishi
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - G Jurisic
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - K Seuwen
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - B Kinzel
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - M G Ludwig
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - J A Wells
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - I N Christie
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - L Koolen
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - A P Abdala
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - B H Liu
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - A V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - A G Teschemacher
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK.
| | - S Kasparov
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK; Baltic Federal University, Kaliningrad 236041, Russian Federation.
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154
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Bourdon AK, Spano GM, Marshall W, Bellesi M, Tononi G, Serra PA, Baghdoyan HA, Lydic R, Campagna SR, Cirelli C. Metabolomic analysis of mouse prefrontal cortex reveals upregulated analytes during wakefulness compared to sleep. Sci Rep 2018; 8:11225. [PMID: 30046159 PMCID: PMC6060152 DOI: 10.1038/s41598-018-29511-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/03/2018] [Indexed: 12/18/2022] Open
Abstract
By identifying endogenous molecules in brain extracellular fluid metabolomics can provide insight into the regulatory mechanisms and functions of sleep. Here we studied how the cortical metabolome changes during sleep, sleep deprivation and spontaneous wakefulness. Mice were implanted with electrodes for chronic sleep/wake recording and with microdialysis probes targeting prefrontal and primary motor cortex. Metabolites were measured using ultra performance liquid chromatography-high resolution mass spectrometry. Sleep/wake changes in metabolites were evaluated using partial least squares discriminant analysis, linear mixed effects model analysis of variance, and machine-learning algorithms. More than 30 known metabolites were reliably detected in most samples. When used by a logistic regression classifier, the profile of these metabolites across sleep, spontaneous wake, and enforced wake was sufficient to assign mice to their correct experimental group (pair-wise) in 80-100% of cases. Eleven of these metabolites showed significantly higher levels in awake than in sleeping mice. Some changes extend previous findings (glutamate, homovanillic acid, lactate, pyruvate, tryptophan, uridine), while others are novel (D-gluconate, N-acetyl-beta-alanine, N-acetylglutamine, orotate, succinate/methylmalonate). The upregulation of the de novo pyrimidine pathway, gluconate shunt and aerobic glycolysis may reflect a wake-dependent need to promote the synthesis of many essential components, from nucleic acids to synaptic membranes.
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Affiliation(s)
- Allen K Bourdon
- Department of Chemistry, University of Tennessee, Knoxville, TN, United States
| | - Giovanna Maria Spano
- Department of Psychiatry, University of Wisconsin, Madison, Madison, WI, United States
| | - William Marshall
- Department of Psychiatry, University of Wisconsin, Madison, Madison, WI, United States
| | - Michele Bellesi
- Department of Psychiatry, University of Wisconsin, Madison, Madison, WI, United States.,Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, Madison, WI, United States
| | - Pier Andrea Serra
- Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy
| | - Helen A Baghdoyan
- Department of Anesthesiology and Psychology, University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ralph Lydic
- Department of Anesthesiology and Psychology, University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Shawn R Campagna
- Department of Chemistry, University of Tennessee, Knoxville, TN, United States. .,Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, TN, United States.
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, Madison, WI, United States.
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155
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Sun S, Li H, Chen J, Qian Q. Lactic Acid: No Longer an Inert and End-Product of Glycolysis. Physiology (Bethesda) 2018; 32:453-463. [PMID: 29021365 DOI: 10.1152/physiol.00016.2017] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/07/2017] [Accepted: 09/07/2017] [Indexed: 12/21/2022] Open
Abstract
For decades, lactic acid has been considered a dead-end product of glycolysis. Research in the last 20+ years has shown otherwise. Through its transporters (MCTs) and receptor (GPR81), lactic acid plays a key role in multiple cellular processes, including energy regulation, immune tolerance, memory formation, wound healing, ischemic tissue injury, and cancer growth and metastasis. We summarize key findings of lactic acid signaling, functions, and many remaining questions.
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Affiliation(s)
- Shiren Sun
- Department of Nephrology, Xijing Hospital, the Fourth Military Medical University, Xian, China
| | - Heng Li
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; and
| | - Jianghua Chen
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; and
| | - Qi Qian
- Department of Medicine, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
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156
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Boitsova EB, Morgun AV, Osipova ED, Pozhilenkova EA, Martinova GP, Frolova OV, Olovannikova RY, Tohidpour A, Gorina YV, Panina YA, Salmina AB. The inhibitory effect of LPS on the expression of GPR81 lactate receptor in blood-brain barrier model in vitro. J Neuroinflammation 2018; 15:196. [PMID: 29973231 PMCID: PMC6030740 DOI: 10.1186/s12974-018-1233-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/22/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Lipopolysaccharide (LPS) is one of the main constituents of the cell wall of gram-negative bacteria. As an endotoxin, LPS induces neuroinflammation, which is associated with the blood-brain barrier impairment. Lactate is a metabolite with some significant physiological functions within the neurovascular unit/blood-brain barrier (BBB). Accumulation of extracellular and cerebrospinal fluid lactate is a specific feature of bacterial meningitis. However, the role of lactate production, transport, and sensing by lactate receptors GPR81 in the pathogenesis of bacterial neuroinflammation is still unknown. METHODS In this study, we analyzed effects of LPS on the expression of GPR81 and MCT-1 and proliferation of cerebral endothelial cells in the BBB model in vitro. We used molecular profiling methods to measure the expression of GPR81, MCT-1, IL-1β, and Ki67 in the cerebral endothelium after treatment with different concentrations of LPS followed by measuring the level of extracellular lactate, transendothelial electric resistance, and permeability of the endothelial cell layer. RESULTS Our findings showed that exposure to LPS results in neuroinflammatory changes associated with decreased expression of GPR81 and MCT-1 in endothelial cells, as well as overproduction of IL-1β and elevation of lactate concentrations in the extracellular space in a dose-dependent manner. LPS treatment reduced JAM tight junction protein expression in cerebral endothelial cells and altered BBB structural integrity in vitro. CONCLUSION The impairment of lactate reception and transport might contribute to the alterations of BBB structural and functional integrity caused by LPS-mediated neuroinflammation.
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Affiliation(s)
- Elizaveta B. Boitsova
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
- Department of Children Infectious Diseases, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Andrey V. Morgun
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
- Department of Pediatrics, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Elena D. Osipova
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Elena A. Pozhilenkova
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Galina P. Martinova
- Department of Children Infectious Diseases, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Olga V. Frolova
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Raissa Ya Olovannikova
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Abolghasem Tohidpour
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Yana V. Gorina
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Yulia A. Panina
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Alla B. Salmina
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
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157
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Alberini CM, Cruz E, Descalzi G, Bessières B, Gao V. Astrocyte glycogen and lactate: New insights into learning and memory mechanisms. Glia 2018; 66:1244-1262. [PMID: 29076603 PMCID: PMC5903986 DOI: 10.1002/glia.23250] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/05/2017] [Accepted: 10/04/2017] [Indexed: 12/12/2022]
Abstract
Memory, the ability to retain learned information, is necessary for survival. Thus far, molecular and cellular investigations of memory formation and storage have mainly focused on neuronal mechanisms. In addition to neurons, however, the brain comprises other types of cells and systems, including glia and vasculature. Accordingly, recent experimental work has begun to ask questions about the roles of non-neuronal cells in memory formation. These studies provide evidence that all types of glial cells (astrocytes, oligodendrocytes, and microglia) make important contributions to the processing of encoded information and storing memories. In this review, we summarize and discuss recent findings on the critical role of astrocytes as providers of energy for the long-lasting neuronal changes that are necessary for long-term memory formation. We focus on three main findings: first, the role of glucose metabolism and the learning- and activity-dependent metabolic coupling between astrocytes and neurons in the service of long-term memory formation; second, the role of astrocytic glucose metabolism in arousal, a state that contributes to the formation of very long-lasting and detailed memories; and finally, in light of the high energy demands of the brain during early development, we will discuss the possible role of astrocytic and neuronal glucose metabolisms in the formation of early-life memories. We conclude by proposing future directions and discussing the implications of these findings for brain health and disease. Astrocyte glycogenolysis and lactate play a critical role in memory formation. Emotionally salient experiences form strong memories by recruiting astrocytic β2 adrenergic receptors and astrocyte-generated lactate. Glycogenolysis and astrocyte-neuron metabolic coupling may also play critical roles in memory formation during development, when the energy requirements of brain metabolism are at their peak.
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Affiliation(s)
- Cristina M Alberini
- Center for Neural Science, New York University, New York, New York, 10003
- Associate Investigator, Neuroscience Institute, NYU Langone Medical Center, New York, New York, 10016
| | - Emmanuel Cruz
- Center for Neural Science, New York University, New York, New York, 10003
| | - Giannina Descalzi
- Center for Neural Science, New York University, New York, New York, 10003
| | - Benjamin Bessières
- Center for Neural Science, New York University, New York, New York, 10003
| | - Virginia Gao
- Center for Neural Science, New York University, New York, New York, 10003
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158
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Herrera-López G, Galván EJ. Modulation of hippocampal excitability via the hydroxycarboxylic acid receptor 1. Hippocampus 2018; 28:557-567. [PMID: 29704292 DOI: 10.1002/hipo.22958] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/19/2018] [Accepted: 04/21/2018] [Indexed: 01/15/2023]
Abstract
In addition to its prominent role as an energetic substrate in the brain, lactate is emerging as a signaling molecule capable of controlling neuronal excitability. The finding that the lactate-activated receptor (hydroxycarboxylic acid receptor 1; HCA1) is widely expressed in the brain opened up the possibility that lactate exerts modulation of neuronal activity via a transmembranal receptor-linked mechanism. Here, we show that lactate causes biphasic modulation of the intrinsic excitability of CA1 pyramidal cells. In the low millimolar range, lactate or the HCA1 agonist 3,5-DHBA reduced the input resistance and membrane time constant. In addition, activation of HCA1 significantly blocked the fast inactivating sodium current and increased the delay from inactivation to a conducting state of the sodium channel. As the observed actions occurred in the presence of 4-CIN, a blocker of the neuronal monocarboxylate transporter, the possibility that lactate acted via neuronal metabolism is unlikely. Consistently, modulation of the intrinsic excitability was abolished when CA1 pyramidal cells were dialyzed with pertussis toxin, indicating the dependency of a Gαi/o -protein-coupled receptor. The activation of HCA1 appears to serve as a restraining mechanism during enhanced network activity and may function as a negative feedback for the astrocytic production of lactate.
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Affiliation(s)
- Gabriel Herrera-López
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Calzada de los Tenorios No. 235, México City 14330, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Calzada de los Tenorios No. 235, México City 14330, México
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159
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Metabolic regulation of synaptic activity. Rev Neurosci 2018; 29:825-835. [DOI: 10.1515/revneuro-2017-0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/16/2018] [Indexed: 12/20/2022]
Abstract
Abstract
Brain tissue is bioenergetically expensive. In humans, it composes approximately 2% of body weight and accounts for approximately 20% of calorie consumption. The brain consumes energy mostly for ion and neurotransmitter transport, a process that occurs primarily in synapses. Therefore, synapses are expensive for any living creature who has brain. In many brain diseases, synapses are damaged earlier than neurons start dying. Synapses may be considered as vulnerable sites on a neuron. Ischemic stroke, an acute disturbance of blood flow in the brain, is an example of a metabolic disease that affects synapses. The associated excessive glutamate release, called excitotoxicity, is involved in neuronal death in brain ischemia. Another example of a metabolic disease is hypoglycemia, a complication of diabetes mellitus, which leads to neuronal death and brain dysfunction. However, synapse function can be corrected with “bioenergetic medicine”. In this review, a ketogenic diet is discussed as a curative option. In support of a ketogenic diet, whereby carbohydrates are replaced for fats in daily meals, epileptic seizures can be terminated. In this review, we discuss possible metabolic sensors in synapses. These may include molecules that perceive changes in composition of extracellular space, for instance, ketone body and lactate receptors, or molecules reacting to changes in cytosol, for instance, KATP channels or AMP kinase. Inhibition of endocytosis is believed to be a universal synaptic mechanism of adaptation to metabolic changes.
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160
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Vardjan N, Chowdhury HH, Horvat A, Velebit J, Malnar M, Muhič M, Kreft M, Krivec ŠG, Bobnar ST, Miš K, Pirkmajer S, Offermanns S, Henriksen G, Storm-Mathisen J, Bergersen LH, Zorec R. Enhancement of Astroglial Aerobic Glycolysis by Extracellular Lactate-Mediated Increase in cAMP. Front Mol Neurosci 2018; 11:148. [PMID: 29867342 PMCID: PMC5953330 DOI: 10.3389/fnmol.2018.00148] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/16/2018] [Indexed: 11/13/2022] Open
Abstract
Besides being a neuronal fuel, L-lactate is also a signal in the brain. Whether extracellular L-lactate affects brain metabolism, in particular astrocytes, abundant neuroglial cells, which produce L-lactate in aerobic glycolysis, is unclear. Recent studies suggested that astrocytes express low levels of the L-lactate GPR81 receptor (EC50 ≈ 5 mM) that is in fat cells part of an autocrine loop, in which the Gi-protein mediates reduction of cytosolic cyclic adenosine monophosphate (cAMP). To study whether a similar signaling loop is present in astrocytes, affecting aerobic glycolysis, we measured the cytosolic levels of cAMP, D-glucose and L-lactate in single astrocytes using fluorescence resonance energy transfer (FRET)-based nanosensors. In contrast to the situation in fat cells, stimulation by extracellular L-lactate and the selective GPR81 agonists, 3-chloro-5-hydroxybenzoic acid (3Cl-5OH-BA) or 4-methyl-N-(5-(2-(4-methylpiperazin-1-yl)-2-oxoethyl)-4-(2-thienyl)-1,3-thiazol-2-yl)cyclohexanecarboxamide (Compound 2), like adrenergic stimulation, elevated intracellular cAMP and L-lactate in astrocytes, which was reduced by the inhibition of adenylate cyclase. Surprisingly, 3Cl-5OH-BA and Compound 2 increased cytosolic cAMP also in GPR81-knock out astrocytes, indicating that the effect is GPR81-independent and mediated by a novel, yet unidentified, excitatory L-lactate receptor-like mechanism in astrocytes that enhances aerobic glycolysis and L-lactate production via a positive feedback mechanism.
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Affiliation(s)
- Nina Vardjan
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Helena H Chowdhury
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jelena Velebit
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Maja Malnar
- Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Marko Muhič
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia.,Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Špela G Krivec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Saša T Bobnar
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Katarina Miš
- Laboratory for Molecular Neurobiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Laboratory for Molecular Neurobiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Gjermund Henriksen
- Nuclear and Energy Physics, Department of Physics, The Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.,Norwegian Medical Cyclotron Centre Ltd., Oslo, Norway
| | - Jon Storm-Mathisen
- Division of Anatomy, Department of Molecular Medicine, CMBN/SERTA Healthy Brain Ageing Centre, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Linda H Bergersen
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.,Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Robert Zorec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
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161
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Geiseler SJ, Morland C. The Janus Face of VEGF in Stroke. Int J Mol Sci 2018; 19:ijms19051362. [PMID: 29734653 PMCID: PMC5983623 DOI: 10.3390/ijms19051362] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/27/2018] [Accepted: 05/01/2018] [Indexed: 12/12/2022] Open
Abstract
The family of vascular endothelial growth factors (VEGFs) are known for their regulation of vascularization. In the brain, VEGFs are important regulators of angiogenesis, neuroprotection and neurogenesis. Dysregulation of VEGFs is involved in a large number of neurodegenerative diseases and acute neurological insults, including stroke. Stroke is the main cause of acquired disabilities, and normally results from an occlusion of a cerebral artery or a hemorrhage, both leading to focal ischemia. Neurons in the ischemic core rapidly undergo necrosis. Cells in the penumbra are exposed to ischemia, but may be rescued if adequate perfusion is restored in time. The neuroprotective and angiogenic effects of VEGFs would theoretically make VEGFs ideal candidates for drug therapy in stroke. However, contradictory to what one might expect, endogenously upregulated levels of VEGF as well as the administration of exogenous VEGF is detrimental in acute stroke. This is probably due to VEGF-mediated blood–brain-barrier breakdown and vascular leakage, leading to edema and increased intracranial pressure as well as neuroinflammation. The key to understanding this Janus face of VEGF function in stroke may lie in the timing; the harmful effect of VEGFs on vessel integrity is transient, as both VEGF preconditioning and increased VEGF after the acute phase has a neuroprotective effect. The present review discusses the multifaceted action of VEGFs in stroke prevention and therapy.
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Affiliation(s)
- Samuel J Geiseler
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, 0371 Oslo, Norway.
| | - Cecilie Morland
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, 0371 Oslo, Norway.
- Institute for Behavioral Sciences, Faculty of Health Sciences, OsloMet-Oslo Metropolitan University, 0166 Oslo, Norway.
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162
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Datta S, Chakrabarti N. Age related rise in lactate and its correlation with lactate dehydrogenase (LDH) status in post-mitochondrial fractions isolated from different regions of brain in mice. Neurochem Int 2018; 118:23-33. [PMID: 29678731 DOI: 10.1016/j.neuint.2018.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/11/2018] [Accepted: 04/11/2018] [Indexed: 02/06/2023]
Abstract
Rise in brain lactate is the hallmark of ageing. Separate studies report that ageing is associated with elevation of lactate level and alterations of lactate dehydrogenase (LDH)-A/B mRNA-expression-ratio in cerebral cortex and hippocampus. However, age related lactate rise in brain and its association with LDH status and their brain regional variations are still elusive. In the present study, level of lactate, LDH (A and B) activity and LDH-A expression were evaluated in post-mitochondrial fraction of tissues isolated from four different brain regions (cerebral cortex, hippocampus, substantia nigra and cerebellum) of young and aged mice. Lactate levels elevated in four brain regions with maximum rise in substantia nigra of aged mice. LDH-A protein expression and its activity decreased in cerebral cortex, hippocampus and substantia nigra without any changes of these parameters in cerebellum of aged mice. LDH-B activity decreased in hippocampus, substantia nigra and cerebellum whereas its activity remains unaltered in cerebral cortex of aged mice. Accordingly, the ratio of LDH-A/LDH-B-activity remains unaltered in hippocampus and substantia nigra, decreased in cerebral cortex and increased in cerebellum. Therefore, rise of lactate in three brain regions (cerebral cortex, hippocampus, substantia nigra) appeared to be not correlated with the alterations of its regulatory enzymes activities in these three brain regions, rather it supports the fact of involvement of other mechanisms, like lactate transport and/or aerobic/anaerobic metabolism as the possible cause(s) of lactate rise in these three brain regions. The increase in LDH-A/LDH-B-activity-ratio appeared to be positively correlated with elevated lactate level in cerebellum of aged mice. Overall, the present study indicates that the mechanism of rise in lactate in brain varies with brain regions where LDH status plays an important role during ageing.
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Affiliation(s)
- Siddhartha Datta
- Department of Physiology, University of Calcutta, Kolkata, West Bengal, India; UGC-CPEPA Centre for "Electro-physiological and Neuro-imaging Studies Including Mathematical Modelling", University of Calcutta, Kolkata, West Bengal, India.
| | - Nilkanta Chakrabarti
- Department of Physiology, University of Calcutta, Kolkata, West Bengal, India; UGC-CPEPA Centre for "Electro-physiological and Neuro-imaging Studies Including Mathematical Modelling", University of Calcutta, Kolkata, West Bengal, India; S. N. Pradhan Centre for Neurosciences, University of Calcutta, Kolkata, West Bengal, India.
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163
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The Science and Translation of Lactate Shuttle Theory. Cell Metab 2018; 27:757-785. [PMID: 29617642 DOI: 10.1016/j.cmet.2018.03.008] [Citation(s) in RCA: 646] [Impact Index Per Article: 107.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 03/16/2018] [Indexed: 02/07/2023]
Abstract
Once thought to be a waste product of anaerobic metabolism, lactate is now known to form continuously under aerobic conditions. Shuttling between producer and consumer cells fulfills at least three purposes for lactate: (1) a major energy source, (2) the major gluconeogenic precursor, and (3) a signaling molecule. "Lactate shuttle" (LS) concepts describe the roles of lactate in delivery of oxidative and gluconeogenic substrates as well as in cell signaling. In medicine, it has long been recognized that the elevation of blood lactate correlates with illness or injury severity. However, with lactate shuttle theory in mind, some clinicians are now appreciating lactatemia as a "strain" and not a "stress" biomarker. In fact, clinical studies are utilizing lactate to treat pro-inflammatory conditions and to deliver optimal fuel for working muscles in sports medicine. The above, as well as historic and recent studies of lactate metabolism and shuttling, are discussed in the following review.
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164
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Jha RR, Singh C, Pant AB, Patel DK. Ionic liquid based ultrasound assisted dispersive liquid-liquid micro-extraction for simultaneous determination of 15 neurotransmitters in rat brain, plasma and cell samples. Anal Chim Acta 2018; 1005:43-53. [DOI: 10.1016/j.aca.2017.12.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 11/28/2017] [Accepted: 12/03/2017] [Indexed: 11/24/2022]
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165
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Millet A, Cuisinier A, Bouzat P, Batandier C, Lemasson B, Stupar V, Pernet-Gallay K, Crespy T, Barbier EL, Payen JF. Hypertonic sodium lactate reverses brain oxygenation and metabolism dysfunction after traumatic brain injury. Br J Anaesth 2018; 120:1295-1303. [PMID: 29793596 DOI: 10.1016/j.bja.2018.01.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/20/2017] [Accepted: 01/30/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The mechanisms by which hypertonic sodium lactate (HSL) solution act in injured brain are unclear. We investigated the effects of HSL on brain metabolism, oxygenation, and perfusion in a rodent model of diffuse traumatic brain injury (TBI). METHODS Thirty minutes after trauma, anaesthetised adult rats were randomly assigned to receive a 3 h infusion of either a saline solution (TBI-saline group) or HSL (TBI-HSL group). The sham-saline and sham-HSL groups received no insult. Three series of experiments were conducted up to 4 h after TBI (or equivalent) to investigate: 1) brain oedema using diffusion-weighted magnetic resonance imaging and brain metabolism using localized 1H-magnetic resonance spectroscopy (n = 10 rats per group). The respiratory control ratio was then determined using oxygraphic analysis of extracted mitochondria, 2) brain oxygenation and perfusion using quantitative blood-oxygenation-level-dependent magnetic resonance approach (n = 10 rats per group), and 3) mitochondrial ultrastructural changes (n = 1 rat per group). RESULTS Compared with the TBI-saline group, the TBI-HSL and the sham-operated groups had reduced brain oedema. Concomitantly, the TBI-HSL group had lower intracellular lactate/creatine ratio [0.049 (0.047-0.098) vs 0.097 (0.079-0.157); P < 0.05], higher mitochondrial respiratory control ratio, higher tissue oxygen saturation [77% (71-79) vs 66% (55-73); P < 0.05], and reduced mitochondrial cristae thickness in astrocytes [27.5 (22.5-38.4) nm vs 38.4 (31.0-47.5) nm; P < 0.01] compared with the TBI-saline group. Serum sodium and lactate concentrations and serum osmolality were higher in the TBI-HSL than in the TBI-saline group. CONCLUSIONS These findings indicate that the hypertonic sodium lactate solution can reverse brain oxygenation and metabolism dysfunction after traumatic brain injury through vasodilatory, mitochondrial, and anti-oedema effects.
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Affiliation(s)
- A Millet
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France; Pôle Couple Enfant, Hôpital Michallon, CHU Grenoble Alpes, Grenoble, France
| | - A Cuisinier
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France; Pôle Anesthésie Réanimation, Hôpital Michallon, CHU Grenoble Alpes, Grenoble, France
| | - P Bouzat
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France; Pôle Anesthésie Réanimation, Hôpital Michallon, CHU Grenoble Alpes, Grenoble, France
| | - C Batandier
- Institut National de la Santé et de la Recherche Médicale, U1055, Laboratoire de Bioénergétique Fondamentale et Appliquée, Université Grenoble Alpes, Grenoble, France
| | - B Lemasson
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France
| | - V Stupar
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France
| | - K Pernet-Gallay
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France
| | - T Crespy
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France; Pôle Anesthésie Réanimation, Hôpital Michallon, CHU Grenoble Alpes, Grenoble, France
| | - E L Barbier
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France
| | - J F Payen
- Institut National de la Santé et de la Recherche Médicale, Grenoble, France; Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France; Pôle Anesthésie Réanimation, Hôpital Michallon, CHU Grenoble Alpes, Grenoble, France.
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166
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Ferguson BS, Rogatzki MJ, Goodwin ML, Kane DA, Rightmire Z, Gladden LB. Lactate metabolism: historical context, prior misinterpretations, and current understanding. Eur J Appl Physiol 2018; 118:691-728. [PMID: 29322250 DOI: 10.1007/s00421-017-3795-6] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Lactate (La-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La- in metabolism begin. The evidence for La- as a major player in the coordination of whole-body metabolism has since grown rapidly. La- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La-'s central role in metabolism and amplifies our understanding of past research.
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Affiliation(s)
- Brian S Ferguson
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew J Rogatzki
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA
| | - Matthew L Goodwin
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.,Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, Canada
| | - Zachary Rightmire
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA.
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167
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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168
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Affiliation(s)
- Rupali Vohra
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Ophthalmology, Copenhagen University Hospital, Rigshospitalet-Glostrup, Glostrup, Denmark
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169
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 952] [Impact Index Per Article: 158.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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170
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Freeman RD, Li B. Neural-metabolic coupling in the central visual pathway. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0357. [PMID: 27574310 DOI: 10.1098/rstb.2015.0357] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2016] [Indexed: 01/19/2023] Open
Abstract
Studies are described which are intended to improve our understanding of the primary measurements made in non-invasive neural imaging. The blood oxygenation level-dependent signal used in functional magnetic resonance imaging (fMRI) reflects changes in deoxygenated haemoglobin. Tissue oxygen concentration, along with blood flow, changes during neural activation. Therefore, measurements of tissue oxygen together with the use of a neural sensor can provide direct estimates of neural-metabolic interactions. We have used this relationship in a series of studies in which a neural microelectrode is combined with an oxygen micro-sensor to make simultaneous co-localized measurements in the central visual pathway. Oxygen responses are typically biphasic with small initial dips followed by large secondary peaks during neural activation. By the use of established visual response characteristics, we have determined that the oxygen initial dip provides a better estimate of local neural function than the positive peak. This contrasts sharply with fMRI for which the initial dip is unreliable. To extend these studies, we have examined the relationship between the primary metabolic agents, glucose and lactate, and associated neural activity. For this work, we also use a Doppler technique to measure cerebral blood flow (CBF) together with neural activity. Results show consistent synchronously timed changes such that increases in neural activity are accompanied by decreases in glucose and simultaneous increases in lactate. Measurements of CBF show clear delays with respect to neural response. This is consistent with a slight delay in blood flow with respect to oxygen delivery during neural activation.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- Ralph D Freeman
- Group in Vision Science, School of Optometry, Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-2020, USA
| | - Baowang Li
- Group in Vision Science, School of Optometry, Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-2020, USA
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171
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Stäubert C, Schöneberg T. GPCR Signaling From Intracellular Membranes - A Novel Concept. Bioessays 2017; 39. [PMID: 29136291 DOI: 10.1002/bies.201700200] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Claudia Stäubert
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
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172
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Wallenius K, Thalén P, Björkman JA, Johannesson P, Wiseman J, Böttcher G, Fjellström O, Oakes ND. Involvement of the metabolic sensor GPR81 in cardiovascular control. JCI Insight 2017; 2:92564. [PMID: 28978803 DOI: 10.1172/jci.insight.92564] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 08/24/2017] [Indexed: 12/21/2022] Open
Abstract
GPR81 is a receptor for the metabolic intermediate lactate with an established role in regulating adipocyte lipolysis. Potentially novel GPR81 agonists were identified that suppressed fasting plasma free fatty acid levels in rodents and in addition improved insulin sensitivity in mouse models of insulin resistance and diabetes. Unexpectedly, the agonists simultaneously induced hypertension in rodents, including wild-type, but not GPR81-deficient mice. Detailed cardiovascular studies in anesthetized dogs showed that the pressor effect was associated with heterogenous effects on vascular resistance among the measured tissues: increasing in the kidney while remaining unchanged in hindlimb and heart. Studies in rats revealed that the pressor effect could be blocked, and the renal resistance effect at least partially blocked, with pharmacological antagonism of endothelin receptors. In situ hybridization localized GPR81 to the microcirculation, notably afferent arterioles of the kidney. In conclusion, these results provide evidence for a potentially novel role of GPR81 agonism in blood pressure control and regulation of renal vascular resistance including modulation of a known vasoeffector mechanism, the endothelin system. In addition, support is provided for the concept of fatty acid lowering as a means of improving insulin sensitivity.
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173
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Toft-Kehler AK, Skytt DM, Kolko M. A Perspective on the Müller Cell-Neuron Metabolic Partnership in the Inner Retina. Mol Neurobiol 2017; 55:5353-5361. [PMID: 28929338 DOI: 10.1007/s12035-017-0760-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/31/2017] [Indexed: 10/18/2022]
Abstract
The Müller cells represent the predominant macroglial cell in the retina. In recent decades, Müller cells have been acknowledged to be far more influential on neuronal homeostasis in the retina than previously assumed. With its unique localization, spanning the entire retina being interposed between the vessels and neurons, Müller cells are responsible for the functional and metabolic support of the surrounding neurons. As a consequence of major energy demands in the retina, high levels of glucose are consumed and processed by Müller cells. The present review provides a perspective on the symbiotic relationship between Müller cells and inner retinal neurons on a cellular level by emphasizing the essential role of energy metabolism within Müller cells in relation to retinal neuron survival.
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Affiliation(s)
- A K Toft-Kehler
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - D M Skytt
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark. .,Department of Ophthalmology, Zealand University Hospital, Vestermarksvej 23, 4000, Roskilde, Denmark. .,Department of Ophthalmology, Copenhagen University Hospital, Rigshospitalet, Nordre Ringvej 57, 2600, Glostrup, Denmark.
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174
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San-Millán I, Brooks GA. Reexamining cancer metabolism: lactate production for carcinogenesis could be the purpose and explanation of the Warburg Effect. Carcinogenesis 2017; 38:119-133. [PMID: 27993896 PMCID: PMC5862360 DOI: 10.1093/carcin/bgw127] [Citation(s) in RCA: 256] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 12/08/2016] [Indexed: 12/15/2022] Open
Abstract
Herein, we use lessons learned in exercise physiology and metabolism to propose that augmented lactate production (‘lactagenesis’), initiated by gene mutations, is the reason and purpose of the Warburg Effect and that dysregulated lactate metabolism and signaling are the key elements in carcinogenesis. Lactate-producing (‘lactagenic’) cancer cells are characterized by increased aerobic glycolysis and excessive lactate formation, a phenomenon described by Otto Warburg 93 years ago, which still remains unexplained. After a hiatus of several decades, interest in lactate as a player in cancer has been renewed. In normal physiology, lactate, the obligatory product of glycolysis, is an important metabolic fuel energy source, the most important gluconeogenic precursor, and a signaling molecule (i.e. a ‘lactormone’) with major regulatory properties. In lactagenic cancers, oncogenes and tumor suppressor mutations behave in a highly orchestrated manner, apparently with the purpose of increasing glucose utilization for lactagenesis purposes and lactate exchange between, within and among cells. Five main steps are identified (i) increased glucose uptake, (ii) increased glycolytic enzyme expression and activity, (iii) decreased mitochondrial function, (iv) increased lactate production, accumulation and release and (v) upregulation of monocarboxylate transporters MTC1 and MCT4 for lactate exchange. Lactate is probably the only metabolic compound involved and necessary in all main sequela for carcinogenesis, specifically: angiogenesis, immune escape, cell migration, metastasis and self-sufficient metabolism. We hypothesize that lactagenesis for carcinogenesis is the explanation and purpose of the Warburg Effect. Accordingly, therapies to limit lactate exchange and signaling within and among cancer cells should be priorities for discovery.
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Affiliation(s)
- Iñigo San-Millán
- Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Physiology Laboratory, CU Sports Medicine and Performance Center, Boulder, CO 80309, USA and
| | - George A Brooks
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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175
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Contribution of Intrinsic Lactate to Maintenance of Seizure Activity in Neocortical Slices from Patients with Temporal Lobe Epilepsy and in Rat Entorhinal Cortex. Int J Mol Sci 2017; 18:ijms18091835. [PMID: 28832554 PMCID: PMC5618484 DOI: 10.3390/ijms18091835] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 08/11/2017] [Accepted: 08/14/2017] [Indexed: 12/20/2022] Open
Abstract
Neuronal lactate uptake supports energy metabolism associated with synaptic signaling and recovery of extracellular ion gradients following neuronal activation. Altered expression of the monocarboxylate transporters (MCT) in temporal lobe epilepsy (TLE) hampers lactate removal into the bloodstream. The resulting increase in parenchymal lactate levels might exert both, anti- and pro-ictogen effects, by causing acidosis and by supplementing energy metabolism, respectively. Hence, we assessed the contribution of lactate to the maintenance of transmembrane potassium gradients, synaptic signaling and pathological network activity in chronic epileptic human tissue. Stimulus induced and spontaneous field potentials and extracellular potassium concentration changes (∆[K⁺]O) were recorded in parallel with tissue pO₂ and pH in slices from TLE patients while blocking MCTs by α-cyano-4-hydroxycinnamic acid (4-CIN) or d-lactate. Intrinsic lactate contributed to the oxidative energy metabolism in chronic epileptic tissue as revealed by the changes in pO₂ following blockade of lactate uptake. However, unlike the results in rat hippocampus, ∆[K⁺]O recovery kinetics and field potential amplitude did not depend on the presence of lactate. Remarkably, inhibition of lactate uptake exerted pH-independent anti-seizure effects both in healthy rat and chronic epileptic tissue and this effect was partly mediated via adenosine 1 receptor activation following decreased oxidative metabolism.
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176
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Rooijackers HM, Wiegers EC, van der Graaf M, Thijssen DH, Kessels RPC, Tack CJ, de Galan BE. A Single Bout of High-Intensity Interval Training Reduces Awareness of Subsequent Hypoglycemia in Patients With Type 1 Diabetes. Diabetes 2017; 66:1990-1998. [PMID: 28420673 DOI: 10.2337/db16-1535] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/11/2017] [Indexed: 11/13/2022]
Abstract
High-intensity interval training (HIIT) has gained increasing popularity in patients with diabetes. HIIT acutely increases plasma lactate levels. This may be important, since the administration of lactate during hypoglycemia suppresses symptoms and counterregulation while preserving cognitive function. We tested the hypothesis that, in the short term, HIIT reduces awareness of hypoglycemia and attenuates hypoglycemia-induced cognitive dysfunction. In a randomized crossover trial, patients with type 1 diabetes and normal awareness of hypoglycemia (NAH), patients with impaired awareness of hypoglycemia (IAH), and healthy participants (n = 10 per group) underwent a hyperinsulinemic-hypoglycemic (2.6 mmol/L) clamp, either after a HIIT session or after seated rest. Compared with rest, HIIT reduced symptoms of hypoglycemia in patients with NAH but not in healthy participants or patients with IAH. HIIT attenuated hypoglycemia-induced cognitive dysfunction, which was mainly driven by changes in the NAH subgroup. HIIT suppressed cortisol and growth hormone responses, but not catecholamine responses to hypoglycemia. The present findings demonstrate that a single HIIT session rapidly reduces awareness of subsequent hypoglycemia in patients with type 1 diabetes and NAH, but does not in patients with IAH, and attenuates hypoglycemia-induced cognitive dysfunction. The role of exercise-induced lactate in mediating these effects, potentially serving as an alternative fuel for the brain, should be further explored.
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Affiliation(s)
- Hanne M Rooijackers
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marinette van der Graaf
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Dick H Thijssen
- Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, U.K
| | - Roy P C Kessels
- Department of Medical Psychology, Radboud University Medical Center, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
| | - Cees J Tack
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
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177
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Upregulated energy metabolism in the Drosophila mushroom body is the trigger for long-term memory. Nat Commun 2017; 8:15510. [PMID: 28580949 PMCID: PMC5465319 DOI: 10.1038/ncomms15510] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 04/04/2017] [Indexed: 01/02/2023] Open
Abstract
Efficient energy use has constrained the evolution of nervous systems. However, it is unresolved whether energy metabolism may resultantly regulate major brain functions. Our observation that Drosophila flies double their sucrose intake at an early stage of long-term memory formation initiated the investigation of how energy metabolism intervenes in this process. Cellular-resolution imaging of energy metabolism reveals a concurrent elevation of energy consumption in neurons of the mushroom body, the fly's major memory centre. Strikingly, upregulation of mushroom body energy flux is both necessary and sufficient to drive long-term memory formation. This effect is triggered by a specific pair of dopaminergic neurons afferent to the mushroom bodies, via the D5-like DAMB dopamine receptor. Hence, dopamine signalling mediates an energy switch in the mushroom body that controls long-term memory encoding. Our data thus point to an instructional role for energy flux in the execution of demanding higher brain functions. Energy consumption in the brain is thought to respond to changes in neuronal activity, without informational role. Here the authors show that increased energy flux in the mushroom body, driven by a pair of input dopaminergic neurons, is a command for the formation of long-term memory in Drosophila.
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178
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Lundgaard I, Lu ML, Yang E, Peng W, Mestre H, Hitomi E, Deane R, Nedergaard M. Glymphatic clearance controls state-dependent changes in brain lactate concentration. J Cereb Blood Flow Metab 2017; 37:2112-2124. [PMID: 27481936 PMCID: PMC5464705 DOI: 10.1177/0271678x16661202] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Brain lactate concentration is higher during wakefulness than in sleep. However, it is unknown why arousal is linked to an increase in brain lactate and why lactate declines within minutes of sleep. Here, we show that the glymphatic system is responsible for state-dependent changes in brain lactate concentration. Suppression of glymphatic function via acetazolamide treatment, cisterna magna puncture, aquaporin 4 deletion, or changes in body position reduced the decline in brain lactate normally observed when awake mice transition into sleep or anesthesia. Concurrently, the same manipulations diminished accumulation of lactate in cervical, but not in inguinal lymph nodes when mice were anesthetized. Thus, our study suggests that brain lactate is an excellent biomarker of the sleep-wake cycle and increases further during sleep deprivation, because brain lactate is inversely correlated with glymphatic-lymphatic clearance. This analysis provides fundamental new insight into brain energy metabolism by demonstrating that glucose that is not fully oxidized can be exported as lactate via glymphatic-lymphatic fluid transport.
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Affiliation(s)
- Iben Lundgaard
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Minh Lon Lu
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA.,2 Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Ezra Yang
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Weiguo Peng
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Humberto Mestre
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Emi Hitomi
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Rashid Deane
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA
| | - Maiken Nedergaard
- 1 Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester, Rochester, NY, USA.,3 Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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179
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Rodents and humans are able to detect the odour of L-Lactate. PLoS One 2017; 12:e0178478. [PMID: 28542639 PMCID: PMC5444829 DOI: 10.1371/journal.pone.0178478] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/12/2017] [Indexed: 01/26/2023] Open
Abstract
L-Lactate (LL) is an essential cellular metabolite which can be used to generate energy. In addition, accumulating evidence suggests that LL is used for inter-cellular signalling. Some LL-sensitive receptors have been identified but we recently proposed that there may be yet another unknown G-protein coupled receptor (GPCR) sensitive to LL in the brain. Olfactory receptors (ORs) represent the largest family of GPCRs and some of them are expressed outside the olfactory system, including brain, making them interesting candidates for non-olfactory LL signalling. One of the “ectopically” expressed ORs, Olfr78 in mice (Olr59 in rats and OR51E2 in humans), reportedly can be activated by LL. This implies that both rodents and humans should be able to detect the LL odour. Surprisingly, this has never been demonstrated. Here we show that mice can detect the odour of LL in odour detection and habituation-dishabituation tasks, and discriminate it from peppermint and vanilla odours. Behaviour of the Olfr78 null mice and wildtype mice in odour detection task was not different, indicating that rodents are equipped with more than one LL-sensitive OR. Rats were also able to use the smell of LL as a cue in an odour-reward associative learning task. When presented to humans, more than 90% of participants detected a smell of LL in solution. Interestingly, LL was perceived differently than acetate or propionate—LL was preferentially reported as a pleasant sweet scent while acetate and propionate were perceived as repulsive sour/acid smells. Subjective perception of LL smell was different in men and women. Taken together, our data demonstrate that both rodents and humans are able to detect the odour of LL. Moreover, in mice, LL perception is not purely mediated by Olfr78. Discovery of further LL-sensitive OR might shed the light on their contribution to LL signalling in the body.
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180
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Morland C, Andersson KA, Haugen ØP, Hadzic A, Kleppa L, Gille A, Rinholm JE, Palibrk V, Diget EH, Kennedy LH, Stølen T, Hennestad E, Moldestad O, Cai Y, Puchades M, Offermanns S, Vervaeke K, Bjørås M, Wisløff U, Storm-Mathisen J, Bergersen LH. Exercise induces cerebral VEGF and angiogenesis via the lactate receptor HCAR1. Nat Commun 2017; 8:15557. [PMID: 28534495 PMCID: PMC5457513 DOI: 10.1038/ncomms15557] [Citation(s) in RCA: 290] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 04/07/2017] [Indexed: 12/13/2022] Open
Abstract
Physical exercise can improve brain function and delay neurodegeneration; however, the initial signal from muscle to brain is unknown. Here we show that the lactate receptor (HCAR1) is highly enriched in pial fibroblast-like cells that line the vessels supplying blood to the brain, and in pericyte-like cells along intracerebral microvessels. Activation of HCAR1 enhances cerebral vascular endothelial growth factor A (VEGFA) and cerebral angiogenesis. High-intensity interval exercise (5 days weekly for 7 weeks), as well as L-lactate subcutaneous injection that leads to an increase in blood lactate levels similar to exercise, increases brain VEGFA protein and capillary density in wild-type mice, but not in knockout mice lacking HCAR1. In contrast, skeletal muscle shows no vascular HCAR1 expression and no HCAR1-dependent change in vascularization induced by exercise or lactate. Thus, we demonstrate that a substance released by exercising skeletal muscle induces supportive effects in brain through an identified receptor.
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MESH Headings
- Animals
- Brain/blood supply
- Capillaries/cytology
- Capillaries/drug effects
- Capillaries/metabolism
- Injections, Subcutaneous
- Lactic Acid/administration & dosage
- Lactic Acid/blood
- Lactic Acid/metabolism
- Male
- Mice
- Mice, Knockout
- Models, Animal
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Neovascularization, Physiologic/physiology
- Pericytes/metabolism
- Physical Conditioning, Animal/physiology
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Vascular Endothelial Growth Factor A/metabolism
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Affiliation(s)
- Cecilie Morland
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- Institute for Behavioral Sciences, Faculty of Health Sciences, Oslo and Akershus University College, NO-0167 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Krister A. Andersson
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- Institute for Behavioral Sciences, Faculty of Health Sciences, Oslo and Akershus University College, NO-0167 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Øyvind P. Haugen
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
| | - Alena Hadzic
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- Institute for Behavioral Sciences, Faculty of Health Sciences, Oslo and Akershus University College, NO-0167 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Liv Kleppa
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Andreas Gille
- Institute for Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, D-68169 Mannheim, Germany
| | - Johanne E. Rinholm
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Vuk Palibrk
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Elisabeth H. Diget
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Lauritz H. Kennedy
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Tomas Stølen
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Eivind Hennestad
- Laboratory of Neural Computation, Department of Physiology, University of Oslo, NO-0317 Oslo, Norway
| | - Olve Moldestad
- Centre for Rare Disorders, Oslo University Hospital, Rikshospitalet, NO-0424 Oslo, Norway
| | - Yiqing Cai
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
| | - Maja Puchades
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Stefan Offermanns
- Max-Planck-Institute for Heart and Lung Research, Department of Pharmacology, D-61231 Bad Nauheim, Germany
| | - Koen Vervaeke
- Laboratory of Neural Computation, Department of Physiology, University of Oslo, NO-0317 Oslo, Norway
| | - Magnar Bjørås
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Ulrik Wisløff
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Jon Storm-Mathisen
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
| | - Linda H. Bergersen
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316 Oslo, Norway
- The Synaptic Neurochemistry Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, NO-0317 Oslo, Norway
- Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
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181
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Oheim M, Schmidt E, Hirrlinger J. Local energy on demand: Are 'spontaneous' astrocytic Ca 2+-microdomains the regulatory unit for astrocyte-neuron metabolic cooperation? Brain Res Bull 2017; 136:54-64. [PMID: 28450076 DOI: 10.1016/j.brainresbull.2017.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/18/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022]
Abstract
Astrocytes are a neural cell type critically involved in maintaining brain energy homeostasis as well as signaling. Like neurons, astrocytes are a heterogeneous cell population. Cortical astrocytes show a complex morphology with a highly branched aborization and numerous fine processes ensheathing the synapses of neighboring neurons, and typically extend one process connecting to blood vessels. Recent studies employing genetically encoded fluorescent calcium (Ca2+) indicators have described 'spontaneous' localized Ca2+-transients in the astrocyte periphery that occur asynchronously, independently of signals in other parts of the cells, and that do not involve somatic Ca2+ transients; however, neither it is known whether these Ca2+-microdomains occur at or near neuronal synapses nor have their molecular basis nor downstream effector(s) been identified. In addition to Ca2+ microdomains, sodium (Na+) transients occur in astrocyte subdomains, too, most likely as a consequence of Na+ co-transport with the neurotransmitter glutamate, which also regulates mitochondrial movements locally - as do cytoplasmic Ca2+ levels. In this review, we cover various aspects of these local signaling events and discuss how structural and biophysical properties of astrocytes might foster such compartmentation. Astrocytes metabolically interact with neurons by providing energy substrates to active neurons. As a single astrocyte branch covers hundreds to thousands of synapses, it is tempting to speculate that these metabolic interactions could occur localized to specific subdomains of astrocytes, perhaps even at the level of small groups of synapses. We discuss how astrocytic metabolism might be regulated at this scale and which signals might contribute to its regulation. We speculate that the astrocytic structures that light up transiently as Ca2+-microdomains might be the functional units of astrocytes linking signaling and metabolic processes to adapt astrocytic function to local energy demands. The understanding of these local regulatory and metabolic interactions will be fundamental to fully appreciate the complexity of brain energy homeostasis as well as its failure in disease and may shed new light on the controversy about neuron-glia bi-directional signaling at the tripartite synapse.
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Affiliation(s)
- Martin Oheim
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France.
| | - Elke Schmidt
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany; Dept. of Neurogenetics, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany.
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182
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Kardos J, Héja L, Jemnitz K, Kovács R, Palkovits M. The nature of early astroglial protection-Fast activation and signaling. Prog Neurobiol 2017; 153:86-99. [PMID: 28342942 DOI: 10.1016/j.pneurobio.2017.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/22/2016] [Accepted: 03/05/2017] [Indexed: 12/14/2022]
Abstract
Our present review is focusing on the uniqueness of balanced astroglial signaling. The balance of excitatory and inhibitory signaling within the CNS is mainly determined by sharp synaptic transients of excitatory glutamate (Glu) and inhibitory γ-aminobutyrate (GABA) acting on the sub-second timescale. Astroglia is involved in excitatory chemical transmission by taking up i) Glu through neurotransmitter-sodium transporters, ii) K+ released due to presynaptic action potential generation, and iii) water keeping osmotic pressure. Glu uptake-coupled Na+ influx may either ignite long-range astroglial Ca2+ transients or locally counteract over-excitation via astroglial GABA release and increased tonic inhibition. Imbalance of excitatory and inhibitory drives is associated with a number of disease conditions, including prevalent traumatic and ischaemic injuries or the emergence of epilepsy. Therefore, when addressing the potential of early therapeutic intervention, astroglial signaling functions combating progress of Glu excitotoxicity is of critical importance. We suggest, that excitotoxicity is linked primarily to over-excitation induced by the impairment of astroglial Glu uptake and/or GABA release. Within this framework, we discuss the acute alterations of Glu-cycling and metabolism and conjecture the therapeutic promise of regulation. We also confer the role played by key carrier proteins and enzymes as well as their interplay at the molecular, cellular, and organ levels. Moreover, based on our former studies, we offer potential prospect on the emerging theme of astroglial succinate sensing in course of Glu excitotoxicity.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary.
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary
| | - Katalin Jemnitz
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary
| | - Richárd Kovács
- Institute of Neurophysiology, Charité - Universitätsmedizin, Berlin, Germany
| | - Miklós Palkovits
- Human Brain Tissue Bank and Laboratory, Semmelweis University, Budapest, Hungary
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183
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Katsu-Jiménez Y, Alves RMP, Giménez-Cassina A. Food for thought: Impact of metabolism on neuronal excitability. Exp Cell Res 2017; 360:41-46. [PMID: 28263755 DOI: 10.1016/j.yexcr.2017.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/11/2022]
Abstract
Neuronal excitability is a highly demanding process that requires high amounts of energy and needs to be exquisitely regulated. For this reason, brain cells display active energy metabolism to support their activity. Independently of their roles as energy substrates, compelling evidence shows that the nature of the fuels that neurons use contribute to fine-tune neuronal excitability. Crosstalk of neurons with glial populations also plays a prominent role in shaping metabolic flow in the brain. In this review, we provide an overview on how different carbon substrates and metabolic pathways impact neurotransmission, and the potential implications for neurological disorders in which neuronal excitability is deregulated, such as epilepsy.
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Affiliation(s)
- Yurika Katsu-Jiménez
- Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Scheeles väg 2, 171 77 Stockholm, Sweden
| | - Renato M P Alves
- Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Scheeles väg 2, 171 77 Stockholm, Sweden
| | - Alfredo Giménez-Cassina
- Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Scheeles väg 2, 171 77 Stockholm, Sweden; Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid, Department of Molecular Biology, C/ Nicolás Cabrera 1, 28049 Madrid, Spain.
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184
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Dienel GA. Lack of appropriate stoichiometry: Strong evidence against an energetically important astrocyte-neuron lactate shuttle in brain. J Neurosci Res 2017; 95:2103-2125. [PMID: 28151548 DOI: 10.1002/jnr.24015] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 11/28/2016] [Accepted: 12/16/2016] [Indexed: 12/22/2022]
Abstract
Glutamate-stimulated aerobic glycolysis in astrocytes coupled with lactate shuttling to neurons where it can be oxidized was proposed as a mechanism to couple excitatory neuronal activity with glucose utilization (CMRglc ) during brain activation. From the outset, this model was not viable because it did not fulfill critical stoichiometric requirements: (i) Calculated glycolytic rates and measured lactate release rates were discordant in cultured astrocytes. (ii) Lactate oxidation requires oxygen consumption, but the oxygen-glucose index (OGI, calculated as CMRO2 /CMRglc ) fell during activation in human brain, and the small rise in CMRO2 could not fully support oxidation of lactate produced by disproportionate increases in CMRglc . (iii) Labeled products of glucose metabolism are not retained in activated rat brain, indicating rapid release of a highly labeled, diffusible metabolite identified as lactate, thereby explaining the CMRglc -CMRO2 mismatch. Additional independent lines of evidence against lactate shuttling include the following: astrocytic oxidation of glutamate after its uptake can help "pay" for its uptake without stimulating glycolysis; blockade of glutamate receptors during activation in vivo prevents upregulation of metabolism and lactate release without impairing glutamate uptake; blockade of β-adrenergic receptors prevents the fall in OGI in activated human and rat brain while allowing glutamate uptake; and neurons upregulate glucose utilization in vivo and in vitro under many stimulatory conditions. Studies in immature cultured cells are not appropriate models for lactate shuttling in adult brain because of their incomplete development of metabolic capability and astrocyte-neuron interactions. Astrocyte-neuron lactate shuttling does not make large, metabolically significant contributions to energetics of brain activation. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico
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185
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Porte B, Chatelain C, Hardouin J, Derambure C, Zerdoumi Y, Hauchecorne M, Dupré N, Bekri S, Gonzalez B, Marret S, Cosette P, Leroux P. Proteomic and transcriptomic study of brain microvessels in neonatal and adult mice. PLoS One 2017; 12:e0171048. [PMID: 28141873 PMCID: PMC5283732 DOI: 10.1371/journal.pone.0171048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/13/2017] [Indexed: 12/17/2022] Open
Abstract
Infants born before 29 weeks gestation incur a major risk of preterm encephalopathy and subependymal/intracerebral/intraventricular haemorrhage. In mice, an ontogenic window of haemorrhage risk was recorded up to 5 days after birth in serpine1 knock-out animals. Using proteome and transcriptome approaches in mouse forebrain microvessels, we previously described the remodelling of extracellular matrix and integrins likely strengthening the vascular wall between postnatal day 5 (P5) and P10. Haemorrhage is the ultimate outcome of vessel damage (i.e., during ischaemia), although discreet vessel insults may be involved in the aetiology of preterm encephalopathy. In this study, we examined proteins identified by mass spectrometry and segregating in gene ontology pathways in forebrain microvessels in P5, P10, and adult wild type mice. In parallel, comparative transcript levels were obtained using RNA hybridization microarrays and enriched biological pathways were extracted from genes exhibiting at least a two-fold change in expression. Five major biological functions were observed in those genes detected both as proteins and mRNA expression undergoing at least a two-fold change in expression in one or more age comparisons: energy metabolism, protein metabolism, antioxidant function, ion exchanges, and transport. Adult microvessels exhibited the highest protein and mRNA expression levels for a majority of genes. Energy metabolism-enriched gene ontology pathways pointed to the preferential occurrence of glycolysis in P5 microvessels cells versus P10 and adult preparations enriched in aerobic oxidative enzymes. Age-dependent levels of RNA coding transport proteins at the plasma membrane and mitochondria strengthened our findings based on protein data. The data suggest that immature microvessels have fewer energy supply alternatives to glycolysis than mature structures. In the context of high energy demand, this constraint might account for vascular damage and maintenance of the high bleeding occurrence in specific areas in immature brain.
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Affiliation(s)
- Baptiste Porte
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Clémence Chatelain
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Julie Hardouin
- Normandie Université, UNIROUEN, UMR-6270, CNRS, IRIB, Mont-Saint-Aignan, France
- Normandie Université, UNIROUEN, Proteomic Facility PISSARO, IRIB, Mont-Saint-Aignan, France
| | - Céline Derambure
- Normandie Université, UNIROUEN, UMR-S905, INSERM, IRIB, Rouen, France
| | - Yasmine Zerdoumi
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Michèle Hauchecorne
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Nicolas Dupré
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Soumeya Bekri
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
- Metabolic Biochemistry Department, Rouen University Hospital, Rouen, France
| | - Bruno Gonzalez
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Stéphane Marret
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
- Neonatal Pediatrics and Intensive Care Department, Rouen University Hospital, Rouen, France
| | - Pascal Cosette
- Normandie Université, UNIROUEN, UMR-6270, CNRS, IRIB, Mont-Saint-Aignan, France
- Normandie Université, UNIROUEN, Proteomic Facility PISSARO, IRIB, Mont-Saint-Aignan, France
| | - Philippe Leroux
- Normandie Université, UNIROUEN, U1245, INSERM, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
- * E-mail:
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186
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Newman LA, Scavuzzo CJ, Gold PE, Korol DL. Training-induced elevations in extracellular lactate in hippocampus and striatum: Dissociations by cognitive strategy and type of reward. Neurobiol Learn Mem 2017; 137:142-153. [PMID: 27919829 PMCID: PMC5215615 DOI: 10.1016/j.nlm.2016.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/27/2016] [Accepted: 12/01/2016] [Indexed: 01/05/2023]
Abstract
Recent evidence suggests that astrocytes convert glucose to lactate, which is released from the astrocytes and supports learning and memory. This report takes a multiple memory perspective to test the role of astrocytes in cognition using real-time lactate measurements during learning and memory. Extracellular lactate levels in the hippocampus or striatum were determined with lactate biosensors while rats were learning place (hippocampus-sensitive) or response (striatum-sensitive) versions of T-mazes. In the first experiment, rats were trained on the place and response tasks to locate a food reward. Extracellular lactate levels in the hippocampus increased beyond those of feeding controls during place training but not during response training. However, striatal lactate levels did not increase beyond those of controls when rats were trained on either the place or the response version of the maze. Because food ingestion itself increased blood glucose and brain lactate levels, the contribution of feeding may have confounded the brain lactate measures. Therefore, we conducted a second similar experiment using water as the reward. A very different pattern of lactate responses to training emerged when water was used as the task reward. First, provision of water itself did not result in large increases in either brain or blood lactate levels. Moreover, extracellular lactate levels increased in the striatum during response but not place learning, whereas extracellular lactate levels in the hippocampus did not differ across tasks. The findings from the two experiments suggest that the relative engagement of the hippocampus and striatum dissociates not only by task but also by reward type. The divergent lactate responses of the hippocampus and striatum in place and response tasks under different reward conditions may reflect ethological constraints tied to foraging for food and water.
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Affiliation(s)
- Lori A Newman
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA
| | - Claire J Scavuzzo
- Department of Psychology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Paul E Gold
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA
| | - Donna L Korol
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA.
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187
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Zhou J, Burns MP, Huynh L, Villapol S, Taub DD, Saavedra JM, Blackman MR. Temporal Changes in Cortical and Hippocampal Expression of Genes Important for Brain Glucose Metabolism Following Controlled Cortical Impact Injury in Mice. Front Endocrinol (Lausanne) 2017; 8:231. [PMID: 28955302 PMCID: PMC5601958 DOI: 10.3389/fendo.2017.00231] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury (TBI) causes transient increases and subsequent decreases in brain glucose utilization. The underlying molecular pathways are orchestrated processes and poorly understood. In the current study, we determined temporal changes in cortical and hippocampal expression of genes important for brain glucose/lactate metabolism and the effect of a known neuroprotective drug telmisartan on the expression of these genes after experimental TBI. Adult male C57BL/6J mice (n = 6/group) underwent sham or unilateral controlled cortical impact (CCI) injury. Their ipsilateral and contralateral cortex and hippocampus were collected 6 h, 1, 3, 7, 14, 21, and 28 days after injury. Expressions of several genes important for brain glucose utilization were determined by qRT-PCR. In results, (1) mRNA levels of three key enzymes in glucose metabolism [hexo kinase (HK) 1, pyruvate kinase, and pyruvate dehydrogenase (PDH)] were all increased 6 h after injury in the contralateral cortex, followed by decreases at subsequent times in the ipsilateral cortex and hippocampus; (2) capillary glucose transporter Glut-1 mRNA increased, while neuronal glucose transporter Glut-3 mRNA decreased, at various times in the ipsilateral cortex and hippocampus; (3) astrocyte lactate transporter MCT-1 mRNA increased, whereas neuronal lactate transporter MCT-2 mRNA decreased in the ipsilateral cortex and hippocampus; (4) HK2 (an isoform of hexokinase) expression increased at all time points in the ipsilateral cortex and hippocampus. GPR81 (lactate receptor) mRNA increased at various time points in the ipsilateral cortex and hippocampus. These temporal alterations in gene expression corresponded closely to the patterns of impaired brain glucose utilization reported in both TBI patients and experimental TBI rodents. The observed changes in hippocampal gene expression were delayed and prolonged, when compared with those in the cortex. The patterns of alterations were specific to different brain regions and exhibited different recovery periods following TBI. Oral administration of telmisartan (1 mg/kg, for 7 days, n = 10 per group) ameliorated cortical or hippocampal mRNA for Glut-1/3, MCT-1/2 and PDH in CCI mice. These data provide molecular evidence for dynamic alteration of multiple critical factors in brain glucose metabolism post-TBI and can inform further research for treating brain metabolic disorders post-TBI.
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Affiliation(s)
- June Zhou
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine, Washington, DC, United States
- *Correspondence: June Zhou,
| | - Mark P. Burns
- Department of Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
| | - Linda Huynh
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
| | - Sonia Villapol
- Department of Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
| | - Daniel D. Taub
- Translational Medicine Section, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular and Cell Biology, Georgetown University School of Medicine, Washington, DC, United States
| | - Juan M. Saavedra
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC, United States
| | - Marc R. Blackman
- Research Service, Washington DC VA Medical Center, Washington, DC, United States
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine, Washington, DC, United States
- Department of Medicine George Washington University School of Medicine, Washington, DC, United States
- Department of Medicine, Georgetown University School of Medicine, Washington, DC, United States
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188
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Patel AB, Lai JCK, Chowdhury GIM, Rothman DL, Behar KL. Comparison of Glutamate Turnover in Nerve Terminals and Brain Tissue During [1,6- 13C 2]Glucose Metabolism in Anesthetized Rats. Neurochem Res 2016; 42:173-190. [PMID: 28025798 DOI: 10.1007/s11064-016-2103-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/06/2016] [Accepted: 11/08/2016] [Indexed: 01/05/2023]
Abstract
The 13C turnover of neurotransmitter amino acids (glutamate, GABA and aspartate) were determined from extracts of forebrain nerve terminals and brain homogenate, and fronto-parietal cortex from anesthetized rats undergoing timed infusions of [1,6-13C2]glucose or [2-13C]acetate. Nerve terminal 13C fractional labeling of glutamate and aspartate was lower than those in whole cortical tissue at all times measured (up to 120 min), suggesting either the presence of a constant dilution flux from an unlabeled substrate or an unlabeled (effectively non-communicating on the measurement timescale) glutamate pool in the nerve terminals. Half times of 13C labeling from [1,6-13C2]glucose, as estimated by least squares exponential fitting to the time course data, were longer for nerve terminals (GluC4, 21.8 min; GABAC2 21.0 min) compared to cortical tissue (GluC4, 12.4 min; GABAC2, 14.5 min), except for AspC3, which was similar (26.5 vs. 27.0 min). The slower turnover of glutamate in the nerve terminals (but not GABA) compared to the cortex may reflect selective effects of anesthesia on activity-dependent glucose use, which might be more pronounced in the terminals. The 13C labeling ratio for glutamate-C4 from [2-13C]acetate over that of 13C-glucose was twice as large in nerve terminals compared to cortex, suggesting that astroglial glutamine under the 13C glucose infusion was the likely source of much of the nerve terminal dilution. The net replenishment of most of the nerve terminal amino acid pools occurs directly via trafficking of astroglial glutamine.
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Affiliation(s)
- Anant B Patel
- Department of Diagnostic Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, 06520, USA. .,CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.
| | - James C K Lai
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello, ID, 83209, USA
| | - Golam I M Chowdhury
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, PO Box 208043, New Haven, CT, 06520, USA
| | - Douglas L Rothman
- Department of Diagnostic Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, PO Box 208043, New Haven, CT, 06520, USA.
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189
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Dienel GA, Rothman DL, Nordström CH. Microdialysate concentration changes do not provide sufficient information to evaluate metabolic effects of lactate supplementation in brain-injured patients. J Cereb Blood Flow Metab 2016; 36:1844-1864. [PMID: 27604313 PMCID: PMC5094313 DOI: 10.1177/0271678x16666552] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Cerebral microdialysis is a widely used clinical tool for monitoring extracellular concentrations of selected metabolites after brain injury and to guide neurocritical care. Extracellular glucose levels and lactate/pyruvate ratios have high diagnostic value because they can detect hypoglycemia and deficits in oxidative metabolism, respectively. In addition, patterns of metabolite concentrations can distinguish between ischemia and mitochondrial dysfunction, and are helpful to choose and evaluate therapy. Increased intracranial pressure can be life-threatening after brain injury, and hypertonic solutions are commonly used for pressure reduction. Recent reports have advocated use of hypertonic sodium lactate, based on claims that it is glucose sparing and provides an oxidative fuel for injured brain. However, changes in extracellular concentrations in microdialysate are not evidence that a rise in extracellular glucose level is beneficial or that lactate is metabolized and improves neuroenergetics. The increase in glucose concentration may reflect inhibition of glycolysis, glycogenolysis, and pentose phosphate shunt pathway fluxes by lactate flooding in patients with mitochondrial dysfunction. In such cases, lactate will not be metabolizable and lactate flooding may be harmful. More rigorous approaches are required to evaluate metabolic and physiological effects of administration of hypertonic sodium lactate to brain-injured patients.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA, and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Carl-Henrik Nordström
- Department of Neurosurgery, Lund University Hospital, Lund, Sweden, and Department of Neurosurgery, Odense University Hospital, Odense, Denmark
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190
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Nalbandian M, Takeda M. Lactate as a Signaling Molecule That Regulates Exercise-Induced Adaptations. BIOLOGY 2016; 5:E38. [PMID: 27740597 PMCID: PMC5192418 DOI: 10.3390/biology5040038] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 09/28/2016] [Indexed: 12/21/2022]
Abstract
Lactate (or its protonated form: lactic acid) has been studied by many exercise scientists. The lactate paradigm has been in constant change since lactate was first discovered in 1780. For many years, it was unfairly seen as primarily responsible for muscular fatigue during exercise and a waste product of glycolysis. The status of lactate has slowly changed to an energy source, and in the last two decades new evidence suggests that lactate may play a much bigger role than was previously believed: many adaptations to exercise may be mediated in some way by lactate. The mechanisms behind these adaptations are yet to be understood. The aim of this review is to present the state of lactate science, focusing on how this molecule may mediate exercise-induced adaptations.
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Affiliation(s)
- Minas Nalbandian
- Graduate School of Sports and Health Science, Doshisha University, Kyoto 610-0394, Japan.
| | - Masaki Takeda
- Faculty of Sports and Health Science, Doshisha University, Kyoto 610-0394, Japan.
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191
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L-Lactate-Mediated Neuroprotection against Glutamate-Induced Excitotoxicity Requires ARALAR/AGC1. J Neurosci 2016; 36:4443-56. [PMID: 27098689 DOI: 10.1523/jneurosci.3691-15.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/20/2016] [Indexed: 01/20/2023] Open
Abstract
UNLABELLED ARALAR/AGC1/Slc25a12, the aspartate-glutamate carrier from brain mitochondria, is the regulatory step in the malate-aspartate NADH shuttle, MAS. MAS is used to oxidize cytosolic NADH in mitochondria, a process required to maintain oxidative glucose utilization. The role of ARALAR was analyzed in two paradigms of glutamate-induced excitotoxicity in cortical neurons: glucose deprivation and acute glutamate stimulation. ARALAR deficiency did not aggravate glutamate-induced neuronal death in vitro, although glutamate-stimulated respiration was impaired. In contrast, the presence of L-lactate as an additional source protected against glutamate-induced neuronal death in control, but not ARALAR-deficient neurons.l-Lactate supplementation increased glutamate-stimulated respiration partially prevented the decrease in the cytosolic ATP/ADP ratio induced by glutamate and substantially diminished mitochondrial accumulation of 8-oxoguanosine, a marker of reactive oxygen species production, only in the presence, but not the absence, of ARALAR. In addition,l-lactate potentiated glutamate-induced increase in cytosolic Ca(2+), in a way independent of the presence of ARALAR. Interestingly,in vivo, the loss of half-a-dose of ARALAR in aralar(+/-)mice enhanced kainic acid-induced seizures and neuronal damage with respect to control animals, in a model of excitotoxicity in which increased L-lactate levels and L-lactate consumption have been previously proven. These results suggest that,in vivo, an inefficient operation of the shuttle in the aralar hemizygous mice prevents the protective role of L-lactate on glutamate excitotoxiciy and that the entry and oxidation of L-lactate through ARALAR-MAS pathway is required for its neuroprotective function. SIGNIFICANCE STATEMENT Lactate now stands as a metabolite necessary for multiple functions in the brain and is an alternative energy source during excitotoxic brain injury. Here we find that the absence of a functional malate-aspartate NADH shuttle caused by aralar/AGC1 disruption causes a block in lactate utilization by neurons, which prevents the protective role of lactate on excitotoxicity, but not glutamate excitotoxicity itself. Thus, failure to use lactate is detrimental and is possibly responsible for the exacerbated in vivo excitotoxicity in aralar(+/-)mice.
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192
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Proia P, Di Liegro CM, Schiera G, Fricano A, Di Liegro I. Lactate as a Metabolite and a Regulator in the Central Nervous System. Int J Mol Sci 2016; 17:E1450. [PMID: 27598136 PMCID: PMC5037729 DOI: 10.3390/ijms17091450] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/22/2016] [Accepted: 08/25/2016] [Indexed: 12/21/2022] Open
Abstract
More than two hundred years after its discovery, lactate still remains an intriguing molecule. Considered for a long time as a waste product of metabolism and the culprit behind muscular fatigue, it was then recognized as an important fuel for many cells. In particular, in the nervous system, it has been proposed that lactate, released by astrocytes in response to neuronal activation, is taken up by neurons, oxidized to pyruvate and used for synthesizing acetyl-CoA to be used for the tricarboxylic acid cycle. More recently, in addition to this metabolic role, the discovery of a specific receptor prompted a reconsideration of its role, and lactate is now seen as a sort of hormone, even involved in processes as complex as memory formation and neuroprotection. As a matter of fact, exercise offers many benefits for our organisms, and seems to delay brain aging and neurodegeneration. Now, exercise induces the production and release of lactate into the blood which can reach the liver, the heart, and also the brain. Can lactate be a beneficial molecule produced during exercise, and offer neuroprotection? In this review, we summarize what we have known on lactate, discussing the roles that have been attributed to this molecule over time.
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Affiliation(s)
- Patrizia Proia
- Department of Psychological, Pedagogical and Educational Sciences, Sport and Exercise Sciences Research Unit, University of Palermo, Palermo I-90128, Italy.
| | - Carlo Maria Di Liegro
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Gabriella Schiera
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Anna Fricano
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo (UNIPA), Palermo I-90128, Italy.
| | - Italia Di Liegro
- Department of Experimental Biomedicine and Clinical Neurosciences (BIONEC), University of Palermo, Palermo I-90127, Italy.
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193
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Angamo EA, Rösner J, Liotta A, Kovács R, Heinemann U. A neuronal lactate uptake inhibitor slows recovery of extracellular ion concentration changes in the hippocampal CA3 region by affecting energy metabolism. J Neurophysiol 2016; 116:2420-2430. [PMID: 27559140 DOI: 10.1152/jn.00327.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 08/13/2016] [Indexed: 01/20/2023] Open
Abstract
Astrocyte-derived lactate supports pathologically enhanced neuronal metabolism, but its role under physiological conditions is still a matter of debate. Here, we determined the contribution of astrocytic neuronal lactate shuttle for maintenance of ion homeostasis and energy metabolism. We tested for the effects of α-cyano-4-hydroxycinnamic acid (4-CIN), which could interfere with energy metabolism by blocking monocarboxylate-transporter 2 (MCT2)-mediated neuronal lactate uptake, on evoked potentials, stimulus-induced changes in K+, Na+, Ca2+, and oxygen concentrations as well as on changes in flavin adenine dinucleotide (FAD) autofluorescence in the hippocampal area CA3. MCT2 blockade by 4-CIN reduced synaptically evoked but not antidromic population spikes. This effect was dependent on the activation of KATP channels indicating reduced neuronal ATP synthesis. By contrast, lactate receptor activation by 3,5-dihydroxybenzoic acid (3,5-DHBA) resulted in increased antidromic and orthodromic population spikes suggesting that 4-CIN effects are not mediated by lactate accumulation and subsequent activation of lactate receptors. Recovery kinetics of all ion transients were prolonged and baseline K+ concentration became elevated by blockade of lactate uptake. Lactate contributed to oxidative metabolism as both baseline respiration and stimulus-induced changes in Po2 were decreased, while FAD fluorescence increased likely due to a reduced conversion of FAD into FADH2 These data suggest that lactate shuttle contributes to regulation of ion homeostatsis and synaptic signaling even in the presence of ample glucose.
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Affiliation(s)
| | - Joerg Rösner
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin, Germany
| | - Agustin Liotta
- Department of Anesthesiology and Intensive Care, Charité Universitätsmedizin, Berlin, Germany
| | - Richard Kovács
- Institute for Neurophysiology, Charité Universitätsmedizin, Berlin, Germany; and
| | - Uwe Heinemann
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin, Germany;
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194
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Jullienne A, Obenaus A, Ichkova A, Savona-Baron C, Pearce WJ, Badaut J. Chronic cerebrovascular dysfunction after traumatic brain injury. J Neurosci Res 2016; 94:609-22. [PMID: 27117494 PMCID: PMC5415378 DOI: 10.1002/jnr.23732] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 02/11/2016] [Accepted: 02/28/2016] [Indexed: 12/12/2022]
Abstract
Traumatic brain injuries (TBI) often involve vascular dysfunction that leads to long-term alterations in physiological and cognitive functions of the brain. Indeed, all the cells that form blood vessels and that are involved in maintaining their proper function can be altered by TBI. This Review focuses on the different types of cerebrovascular dysfunction that occur after TBI, including cerebral blood flow alterations, autoregulation impairments, subarachnoid hemorrhage, vasospasms, blood-brain barrier disruption, and edema formation. We also discuss the mechanisms that mediate these dysfunctions, focusing on the cellular components of cerebral blood vessels (endothelial cells, smooth muscle cells, astrocytes, pericytes, perivascular nerves) and their known and potential roles in the secondary injury cascade. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Amandine Jullienne
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
| | - Andre Obenaus
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
- Department of Physiology, Loma Linda University School of Medicine, Loma Linda, California
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California Riverside, Riverside, California
| | | | | | - William J Pearce
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Jerome Badaut
- Department of Physiology, Loma Linda University School of Medicine, Loma Linda, California
- CNRS UMR5287, University of Bordeaux, Bordeaux, France
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195
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Dienel GA, Cruz NF. Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism. J Neurochem 2016; 138:14-52. [DOI: 10.1111/jnc.13630] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Gerald A. Dienel
- Department of Cell Biology and Physiology; University of New Mexico; Albuquerque; New Mexico USA
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
| | - Nancy F. Cruz
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
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196
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Vestergaard MB, Lindberg U, Aachmann-Andersen NJ, Lisbjerg K, Christensen SJ, Law I, Rasmussen P, Olsen NV, Larsson HBW. Acute hypoxia increases the cerebral metabolic rate - a magnetic resonance imaging study. J Cereb Blood Flow Metab 2016; 36:1046-58. [PMID: 26661163 PMCID: PMC4904346 DOI: 10.1177/0271678x15606460] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/10/2015] [Indexed: 11/15/2022]
Abstract
The aim of the present study was to examine changes in cerebral metabolism by magnetic resonance imaging of healthy subjects during inhalation of 10% O2 hypoxic air. Hypoxic exposure elevates cerebral perfusion, but its effect on energy metabolism has been less investigated. Magnetic resonance imaging techniques were used to measure global cerebral blood flow and the venous oxygen saturation in the sagittal sinus. Global cerebral metabolic rate of oxygen was quantified from cerebral blood flow and arteriovenous oxygen saturation difference. Concentrations of lactate, glutamate, N-acetylaspartate, creatine and phosphocreatine were measured in the visual cortex by magnetic resonance spectroscopy. Twenty-three young healthy males were scanned for 60 min during normoxia, followed by 40 min of breathing hypoxic air. Inhalation of hypoxic air resulted in an increase in cerebral blood flow of 15.5% (p = 0.058), and an increase in cerebral metabolic rate of oxygen of 8.5% (p = 0.035). Cerebral lactate concentration increased by 180.3% ([Formula: see text]), glutamate increased by 4.7% ([Formula: see text]) and creatine and phosphocreatine decreased by 15.2% (p[Formula: see text]). The N-acetylaspartate concentration was unchanged (p = 0.36). In conclusion, acute hypoxia in healthy subjects increased perfusion and metabolic rate, which could represent an increase in neuronal activity. We conclude that marked changes in brain homeostasis occur in the healthy human brain during exposure to acute hypoxia.
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Affiliation(s)
- Mark B Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark
| | - Niels Jacob Aachmann-Andersen
- Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Lisbjerg
- Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Just Christensen
- Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ian Law
- Institute of Clinical Medicine, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Peter Rasmussen
- Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels V Olsen
- Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark Department of Neuroanaesthesia, The Neuroscience Centre, Rigshospitalet, Copenhagen, Denmark
| | - Henrik B W Larsson
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark Institute of Clinical Medicine, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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197
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Banerjee A, Ghatak S, Sikdar SK. l-Lactate mediates neuroprotection against ischaemia by increasing TREK1 channel expression in rat hippocampal astrocytes in vitro. J Neurochem 2016; 138:265-81. [PMID: 27062641 DOI: 10.1111/jnc.13638] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 04/04/2016] [Accepted: 04/04/2016] [Indexed: 12/20/2022]
Abstract
Brain ischaemia is a highly debilitating condition where shortage of oxygen and glucose leads to profuse cell death. Lactate is a neuroprotective metabolite whose concentrations increase up to 15-30 mmol/L during ischaemia and TREK1 is a neuroprotective potassium channel which is upregulated during ischaemia. The aim of this study was to investigate the effect of l-lactate on TREK1 expression and to evaluate the role of l-lactate-TREK1 interaction in conferring neuroprotection in ischaemia-prone hippocampus. We show that 15-30 mmol/L l-lactate increases functional TREK1 protein expression by 1.5-3-fold in hippocampal astrocytes using immunostaining and electrophysiology. Studies with transcription blocker actinomycin-D and quantitative PCR indicate that the increase in TREK1 expression is due to enhanced TREK1 mRNA transcription. We further report that l-lactate-mediated increase in TREK1 expression is via protein kinase A (PKA)-dependent pathway. This is the first report of an ischaemic metabolite affecting functional expression of an ion channel. Our studies in an in vitro model of ischaemia using oxygen glucose deprivation show that 30 mmol/L l-lactate fails to reduce cell death in rat hippocampal slices treated with TREK1 blockers, PKA inhibitors and gliotoxin. The above effects were specific to l-lactate as pyruvate failed to increase TREK1 expression and reduce cell death. l-Lactate-induced TREK1 upregulation is a novel finding of physiological significance as TREK1 channels contribute to neuroprotection by enhancing potassium buffering and glutamate clearance capacity of astrocytes. We propose that l-lactate promotes neuronal survival in hippocampus by increasing TREK1 channel expression via PKA pathway in astrocytes during ischaemia. Insufficient blood supply to the brain leads to cerebral ischaemia and increase in extracellular lactate concentrations. We incubated hippocampal astrocytes in lactate and observed increase in TREK1 channel expression via protein kinase A (PKA). Inhibition of TREK1, PKA and metabolic impairment of astrocytes prevented lactate from reducing cell death in ischaemic hippocampus. This pathway serves as an alternate mechanism of neuroprotection. Cover image for this issue: doi: 10.1111/jnc.13326.
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Affiliation(s)
- Aditi Banerjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Swagata Ghatak
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
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Jha MK, Lee IK, Suk K. Metabolic reprogramming by the pyruvate dehydrogenase kinase-lactic acid axis: Linking metabolism and diverse neuropathophysiologies. Neurosci Biobehav Rev 2016; 68:1-19. [PMID: 27179453 DOI: 10.1016/j.neubiorev.2016.05.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/11/2016] [Accepted: 05/09/2016] [Indexed: 12/12/2022]
Abstract
Emerging evidence indicates that there is a complex interplay between metabolism and chronic disorders in the nervous system. In particular, the pyruvate dehydrogenase (PDH) kinase (PDK)-lactic acid axis is a critical link that connects metabolic reprogramming and the pathophysiology of neurological disorders. PDKs, via regulation of PDH complex activity, orchestrate the conversion of pyruvate either aerobically to acetyl-CoA, or anaerobically to lactate. The kinases are also involved in neurometabolic dysregulation under pathological conditions. Lactate, an energy substrate for neurons, is also a recently acknowledged signaling molecule involved in neuronal plasticity, neuron-glia interactions, neuroimmune communication, and nociception. More recently, the PDK-lactic acid axis has been recognized to modulate neuronal and glial phenotypes and activities, contributing to the pathophysiologies of diverse neurological disorders. This review covers the recent advances that implicate the PDK-lactic acid axis as a novel linker of metabolism and diverse neuropathophysiologies. We finally explore the possibilities of employing the PDK-lactic acid axis and its downstream mediators as putative future therapeutic strategies aimed at prevention or treatment of neurological disorders.
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Affiliation(s)
- Mithilesh Kumar Jha
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea; Department of Neurology, Division of Neuromuscular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - In-Kyu Lee
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
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199
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Steinman MQ, Gao V, Alberini CM. The Role of Lactate-Mediated Metabolic Coupling between Astrocytes and Neurons in Long-Term Memory Formation. Front Integr Neurosci 2016; 10:10. [PMID: 26973477 PMCID: PMC4776217 DOI: 10.3389/fnint.2016.00010] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/15/2016] [Indexed: 01/07/2023] Open
Abstract
Long-term memory formation, the ability to retain information over time about an experience, is a complex function that affects multiple behaviors, and is an integral part of an individual's identity. In the last 50 years many scientists have focused their work on understanding the biological mechanisms underlying memory formation and processing. Molecular studies over the last three decades have mostly investigated, or given attention to, neuronal mechanisms. However, the brain is composed of different cell types that, by concerted actions, cooperate to mediate brain functions. Here, we consider some new insights that emerged from recent studies implicating astrocytic glycogen and glucose metabolisms, and particularly their coupling to neuronal functions via lactate, as an essential mechanism for long-term memory formation.
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Affiliation(s)
| | - Virginia Gao
- Center for Neural Science, New York University New York, NY, USA
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200
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Glutamate and ATP at the Interface Between Signaling and Metabolism in Astroglia: Examples from Pathology. Neurochem Res 2016; 42:19-34. [PMID: 26915104 DOI: 10.1007/s11064-016-1848-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 12/17/2022]
Abstract
Glutamate is the main excitatory transmitter in the brain, while ATP represents the most important energy currency in any living cell. Yet, these chemicals play an important role in both processes, enabling them with dual-acting functions in metabolic and intercellular signaling pathways. Glutamate can fuel ATP production, while ATP can act as a transmitter in intercellular signaling. We discuss the interface between glutamate and ATP in signaling and metabolism of astrocytes. Not only do glutamate and ATP cross each other's paths in physiology of the brain, but they also do so in its pathology. We present the fabric of this process in (patho)physiology through the discussion of synthesis and metabolism of ATP and glutamate in astrocytes as well as by providing a general description of astroglial receptors for these molecules along with the downstream signaling pathways that may be activated. It is astroglial receptors for these dual-acting molecules that could hold a key for medical intervention in pathological conditions. We focus on two examples disclosing the role of activation of astroglial ATP and glutamate receptors in pathology of two kinds of brain tissue, gray matter and white matter, respectively. Interventions at the interface of metabolism and signaling show promise for translational medicine.
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