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Corales LG, Inada H, Owada Y, Osumi N. Fatty acid preference for beta-oxidation in mitochondria of murine cultured astrocytes. Genes Cells 2024; 29:757-768. [PMID: 38965717 DOI: 10.1111/gtc.13144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Revised: 06/24/2024] [Accepted: 06/26/2024] [Indexed: 07/06/2024]
Abstract
The brain utilizes glucose as a primary energy substrate but also fatty acids for the β-oxidation in mitochondria. The β-oxidation is reported to occur mainly in astrocytes, but its capacity and efficacy against different fatty acids remain unknown. Here, we show the fatty acid preference for the β-oxidation in mitochondria of murine cultured astrocytes. Fatty acid oxidation assay using an extracellular flux analyzer showed that saturated or monosaturated fatty acids, palmitic acid and oleic acid, are preferred substrates over polyunsaturated fatty acids like arachidonic acid and docosahexaenoic acid. We also report that fatty acid binding proteins expressed in the astrocytes contribute less to fatty acid transport to mitochondria for β-oxidation. Our results could give insight into understanding energy metabolism through fatty acid consumption in the brain.
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Affiliation(s)
- Laarni Grace Corales
- Department of Developmental Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Hitoshi Inada
- Department of Developmental Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, Japan
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Owada
- Department of Organ Anatomy, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Noriko Osumi
- Department of Developmental Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, Japan
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2
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Kim D, Lee SH, Hwang HS, Kim SJ, Yun M. Recent Update on PET/CT Radiotracers for Imaging Cerebral Glioma. Nucl Med Mol Imaging 2024; 58:237-245. [PMID: 38932755 PMCID: PMC11196511 DOI: 10.1007/s13139-024-00847-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/16/2024] [Accepted: 01/29/2024] [Indexed: 06/28/2024] Open
Abstract
Positron emission tomography/computed tomography (PET/CT) has dramatically altered the landscape of noninvasive glioma evaluation, offering complementary insights to those gained through magnetic resonance imaging (MRI). PET/CT scans enable a multifaceted analysis of glioma biology, supporting clinical applications from grading and differential diagnosis to mapping the full extent of tumors and planning subsequent treatments and evaluations. With a broad array of specialized radiotracers, researchers and clinicians can now probe various biological characteristics of gliomas, such as glucose utilization, cellular proliferation, oxygen deficiency, amino acid trafficking, and reactive astrogliosis. This review aims to provide a recent update on the application of versatile PET/CT radiotracers in glioma research and clinical practice.
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Affiliation(s)
- Dongwoo Kim
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722 Republic of Korea
| | - Suk-Hyun Lee
- Department of Radiology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, 07441 Republic of Korea
| | - Hee Sung Hwang
- Department of Nuclear Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, 14068 Republic of Korea
| | - Sun Jung Kim
- Department of Nuclear Medicine, National Health Insurance Service Ilsan Hospital, Goyang, 10444 Republic of Korea
| | - Mijin Yun
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722 Republic of Korea
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3
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Kim D, Ko HY, Chung JI, Park YM, Lee S, Kim SY, Kim J, Chun JH, Han KS, Lee M, Ju YH, Park SJ, Park KD, Nam MH, Kim SH, Shim JK, Park Y, Lim H, Park J, Lee GH, Kim H, Kim S, Park U, Ryu H, Lee SY, Park S, Kang SG, Chang JH, Lee CJ, Yun M. Visualizing cancer-originating acetate uptake through monocarboxylate transporter 1 in reactive astrocytes in the glioblastoma tumor microenvironment. Neuro Oncol 2024; 26:843-857. [PMID: 38085571 PMCID: PMC11066945 DOI: 10.1093/neuonc/noad243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2024] Open
Abstract
BACKGROUND Reactive astrogliosis is a hallmark of various brain pathologies, including neurodegenerative diseases and glioblastomas. However, the specific intermediate metabolites contributing to reactive astrogliosis remain unknown. This study investigated how glioblastomas induce reactive astrogliosis in the neighboring microenvironment and explore 11C-acetate PET as an imaging technique for detecting reactive astrogliosis. METHODS Through in vitro, mouse models, and human tissue experiments, we examined the association between elevated 11C-acetate uptake and reactive astrogliosis in gliomas. We explored acetate from glioblastoma cells, which triggers reactive astrogliosis in neighboring astrocytes by upregulating MAO-B and monocarboxylate transporter 1 (MCT1) expression. We evaluated the presence of cancer stem cells in the reactive astrogliosis region of glioblastomas and assessed the correlation between the volume of 11C-acetate uptake beyond MRI and prognosis. RESULTS Elevated 11C-acetate uptake is associated with reactive astrogliosis and astrocytic MCT1 in the periphery of glioblastomas in human tissues and mouse models. Glioblastoma cells exhibit increased acetate production as a result of glucose metabolism, with subsequent secretion of acetate. Acetate derived from glioblastoma cells induces reactive astrogliosis in neighboring astrocytes by increasing the expression of MAO-B and MCT1. We found cancer stem cells within the reactive astrogliosis at the tumor periphery. Consequently, a larger volume of 11C-acetate uptake beyond contrast-enhanced MRI was associated with a worse prognosis. CONCLUSIONS Our results highlight the role of acetate derived from glioblastoma cells in inducing reactive astrogliosis and underscore the potential value of 11C-acetate PET as an imaging technique for detecting reactive astrogliosis, offering important implications for the diagnosis and treatment of glioblastomas.
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Affiliation(s)
- Dongwoo Kim
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hae Young Ko
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jee-In Chung
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Yongmin Mason Park
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Republic of Korea
- IBS School, University of Science and Technology, Daejeon, Republic of Korea
| | - Sangwon Lee
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seon Yoo Kim
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jisu Kim
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Joong-Hyun Chun
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyung-Seok Han
- Department of Biological Sciences, Chungnam National University, Daejeon, Republic of Korea
| | - Misu Lee
- Division of Life Science, College of Life Science and Bioengineering, Incheon National University, Incheon, Republic of Korea
| | - Yeon Ha Ju
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Republic of Korea
- IBS School, University of Science and Technology, Daejeon, Republic of Korea
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Sun Jun Park
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Division of Bio-Med Science & Technology, KIST School, Korea University of Science and Technology, Seoul, Republic of Korea
| | - Ki Duk Park
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Division of Bio-Med Science & Technology, KIST School, Korea University of Science and Technology, Seoul, Republic of Korea
| | - Min-Ho Nam
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Division of Bio-Med Science & Technology, KIST School, Korea University of Science and Technology, Seoul, Republic of Korea
- Department of KHU-KIST Convergence Science and Technology, Kyung Hee University, Seoul, Republic of Korea
| | - Se Hoon Kim
- Department of Pathology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jin-Kyoung Shim
- Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Youngjoo Park
- Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hyunkeong Lim
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jaekyung Park
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Gwan-Ho Lee
- Research Resources Division, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Hyunjin Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Suhyun Kim
- K-Laboratory, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Uiyeol Park
- K-Laboratory, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Hoon Ryu
- K-Laboratory, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - So Yun Lee
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, Republic of Korea
| | - Sunghyouk Park
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, Republic of Korea
| | - Seok-Gu Kang
- Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jong Hee Chang
- Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - C Justin Lee
- IBS School, University of Science and Technology, Daejeon, Republic of Korea
| | - Mijin Yun
- Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
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Rothman DL, Behar KL, Dienel GA. Mechanistic stoichiometric relationship between the rates of neurotransmission and neuronal glucose oxidation: Reevaluation of and alternatives to the pseudo-malate-aspartate shuttle model. J Neurochem 2024; 168:555-591. [PMID: 36089566 DOI: 10.1111/jnc.15619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/08/2022] [Accepted: 04/15/2022] [Indexed: 11/26/2022]
Abstract
The ~1:1 stoichiometry between the rates of neuronal glucose oxidation (CMRglc-ox-N) and glutamate (Glu)/γ-aminobutyric acid (GABA)-glutamine (Gln) neurotransmitter (NT) cycling between neurons and astrocytes (VNTcycle) has been firmly established. However, the mechanistic basis for this relationship is not fully understood, and this knowledge is critical for the interpretation of metabolic and brain imaging studies in normal and diseased brain. The pseudo-malate-aspartate shuttle (pseudo-MAS) model established the requirement for glycolytic metabolism in cultured glutamatergic neurons to produce NADH that is shuttled into mitochondria to support conversion of extracellular Gln (i.e., astrocyte-derived Gln in vivo) into vesicular neurotransmitter Glu. The evaluation of this model revealed that it could explain half of the 1:1 stoichiometry and it has limitations. Modifications of the pseudo-MAS model were, therefore, devised to address major knowledge gaps, that is, submitochondrial glutaminase location, identities of mitochondrial carriers for Gln and other model components, alternative mechanisms to transaminate α-ketoglutarate to form Glu and shuttle glutamine-derived ammonia while maintaining mass balance. All modified models had a similar 0.5 to 1.0 predicted mechanistic stoichiometry between VNTcycle and the rate of glucose oxidation. Based on studies of brain β-hydroxybutyrate oxidation, about half of CMRglc-ox-N may be linked to glutamatergic neurotransmission and localized in pre-synaptic structures that use pseudo-MAS type mechanisms for Glu-Gln cycling. In contrast, neuronal compartments that do not participate in transmitter cycling may use the MAS to sustain glucose oxidation. The evaluation of subcellular compartmentation of neuronal glucose metabolism in vivo is a critically important topic for future studies to understand glutamatergic and GABAergic neurotransmission.
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Affiliation(s)
- Douglas L Rothman
- Magnetic Resonance Research Center and Departments of Radiology and Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Kevin L Behar
- Magnetic Resonance Research Center and Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
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Dienel GA, Schousboe A, McKenna MC, Rothman DL. A tribute to Leif Hertz: The historical context of his pioneering studies of the roles of astrocytes in brain energy metabolism, neurotransmission, cognitive functions, and pharmacology identifies important, unresolved topics for future studies. J Neurochem 2024; 168:461-495. [PMID: 36928655 DOI: 10.1111/jnc.15812] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023]
Abstract
Leif Hertz, M.D., D.Sc. (honōris causā) (1930-2018), was one of the original and noteworthy participants in the International Conference on Brain Energy Metabolism (ICBEM) series since its inception in 1993. The biennial ICBEM conferences are organized by neuroscientists interested in energetics and metabolism underlying neural functions; they have had a high impact on conceptual and experimental advances in these fields and on promoting collaborative interactions among neuroscientists. Leif made major contributions to ICBEM discussions and understanding of metabolic and signaling characteristics of astrocytes and their roles in brain function. His studies ranged from uptake of K+ from extracellular fluid and its stimulation of astrocytic respiration, identification, and regulation of enzymes specifically or preferentially expressed in astrocytes in the glutamate-glutamine cycle of excitatory neurotransmission, a requirement for astrocytic glycogenolysis for fueling K+ uptake, involvement of glycogen in memory consolidation in the chick, and pharmacology of astrocytes. This tribute to Leif Hertz highlights his major discoveries, the high impact of his work on astrocyte-neuron interactions, and his unparalleled influence on understanding the cellular basis of brain energy metabolism. His work over six decades has helped integrate the roles of astrocytes into neurotransmission where oxidative and glycogenolytic metabolism during neurotransmitter glutamate turnover are key aspects of astrocytic energetics. Leif recognized that brain astrocytic metabolism is greatly underestimated unless the volume fraction of astrocytes is taken into account. Adjustment for pathway rates expressed per gram tissue for volume fraction indicates that astrocytes have much higher oxidative rates than neurons and astrocytic glycogen concentrations and glycogenolytic rates during sensory stimulation in vivo are similar to those in resting and exercising muscle, respectively. These novel insights are typical of Leif's astute contributions to the energy metabolism field, and his publications have identified unresolved topics that provide the neuroscience community with challenges and opportunities for future research.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, 72205, USA
- Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, 87131, USA
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, 21201, USA
| | - Douglas L Rothman
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, Connecticut, 06520, USA
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6
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Satrustegui J, Larrubia PL, Rodrigues TB, Choi IY, McKenna MC. A tribute to Sebastián Cerdán and his key contributions to brain metabolism. J Neurochem 2024; 168:455-460. [PMID: 37169729 DOI: 10.1111/jnc.15828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 04/06/2023] [Indexed: 05/13/2023]
Abstract
This is a tribute to Sebastián Cerdán, a brilliant and innovative NMR spectroscopist whose studies contributed greatly to the fundamental information to the understanding of brain metabolism, particularly in regard to multinuclear magnetic resonance spectroscopy (MRS) techniques. Sebastián Cerdán sadly passed away in May 2022. He was a wonderful mentor and colleague who will be greatly missed.
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Affiliation(s)
- Jorgina Satrustegui
- Departamento de Biologia Molecular & Centro de Biología Molecular Severo Ochoa CSIC-UAM, Madrid, Spain
| | | | - Tiago B Rodrigues
- Member of the Parliament and President of the Parliamentary Committee of Environment and Energy Portuguese Parliament, Lisbon, Portugal
| | - In-Young Choi
- Department of Neurology, Department of Radiology, Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, USA
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7
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Nantogma S, Chowdhury MRH, Kabir MSH, Adelabu I, Joshi SM, Samoilenko A, de Maissin H, Schmidt AB, Nikolaou P, Chekmenev YA, Salnikov OG, Chukanov NV, Koptyug IV, Goodson BM, Chekmenev EY. MATRESHCA: Microtesla Apparatus for Transfer of Resonance Enhancement of Spin Hyperpolarization via Chemical Exchange and Addition. Anal Chem 2024; 96:4171-4179. [PMID: 38358916 PMCID: PMC10939749 DOI: 10.1021/acs.analchem.3c05233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
We present an integrated, open-source device for parahydrogen-based hyperpolarization processes in the microtesla field regime with a cost of components of less than $7000. The device is designed to produce a batch of 13C and 15N hyperpolarized (HP) compounds via hydrogenative or non-hydrogenative parahydrogen-induced polarization methods that employ microtesla magnetic fields for efficient polarization transfer of parahydrogen-derived spin order to X-nuclei (e.g., 13C and 15N). The apparatus employs a layered structure (reminiscent of a Russian doll "Matryoshka") that includes a nonmagnetic variable-temperature sample chamber, a microtesla magnetic field coil (operating in the range of 0.02-75 microtesla), a three-layered mu-metal shield (to attenuate the ambient magnetic field), and a magnetic shield degaussing coil placed in the overall device enclosure. The gas-handling manifold allows for parahydrogen-gas flow and pressure control (up to 9.2 bar of total parahydrogen pressure). The sample temperature can be varied either using a water bath or a PID-controlled heat exchanger in the range from -12 to 80 °C. This benchtop device measures 62 cm (length) × 47 cm (width) × 47 cm (height), weighs 30 kg, and requires only connections to a high-pressure parahydrogen gas supply and a single 110/220 VAC power source. The utility of the device has been demonstrated using an example of parahydrogen pairwise addition to form HP ethyl [1-13C]acetate (P13C = 7%, [c] = 1 M). Moreover, the Signal Amplification By Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) technique was employed to demonstrate efficient hyperpolarization of 13C and 15N spins in a wide range of biologically relevant molecules, including [1-13C]pyruvate (P13C = 14%, [c] = 27 mM), [1-13C]-α-ketoglutarate (P13C = 17%), [1-13C]ketoisocaproate (P13C = 18%), [15N3]metronidazole (P15N = 13%, [c] = 20 mM), and others. While the vast majority of the utility studies have been performed in standard 5 mm NMR tubes, the sample chamber of the device can accommodate a wide range of sample container sizes and geometries of up to 1 L sample volume. The device establishes an integrated, simple, inexpensive, and versatile equipment gateway needed to facilitate parahydrogen-based hyperpolarization experiments ranging from basic science to preclinical applications; indeed, detailed technical drawings and a bill of materials are provided to support the ready translation of this design to other laboratories.
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Affiliation(s)
- Shiraz Nantogma
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Md Raduanul H. Chowdhury
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Mohammad S. H. Kabir
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Isaiah Adelabu
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Sameer M. Joshi
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Anna Samoilenko
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
| | - Henri de Maissin
- German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
- Division of Medical Physics, Department of Radiology, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg 79106, Germany
| | - Andreas B. Schmidt
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
- German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
- Division of Medical Physics, Department of Radiology, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg 79106, Germany
| | | | | | - Oleg G. Salnikov
- International Tomography Center SB RAS, Institutskaya Street 3A, Novosibirsk 630090, Russia
| | - Nikita V. Chukanov
- International Tomography Center SB RAS, Institutskaya Street 3A, Novosibirsk 630090, Russia
| | - Igor V. Koptyug
- International Tomography Center SB RAS, Institutskaya Street 3A, Novosibirsk 630090, Russia
| | - Boyd M. Goodson
- Department of Chemistry and Biochemistry, Materials Technology Center, Southern Illinois University, Carbondale, Illinois 62901, United States
| | - Eduard Y. Chekmenev
- Department of Chemistry, Integrative Biosciences (Ibio), Wayne State University, Karmanos Cancer Institute (KCI), Detroit, Michigan 48202, United States
- Russian Academy of Sciences, Leninskiy Prospekt 14, Moscow 119991, Russia
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Metabolism of Exogenous [2,4- 13C]β-Hydroxybutyrate following Traumatic Brain Injury in 21-22-Day-Old Rats: An Ex Vivo NMR Study. Metabolites 2022; 12:metabo12080710. [PMID: 36005582 PMCID: PMC9414923 DOI: 10.3390/metabo12080710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 02/04/2023] Open
Abstract
Traumatic brain injury (TBI) is leading cause of morbidity in young children. Acute dysregulation of oxidative glucose metabolism within the first hours after injury is a hallmark of TBI. The developing brain relies on ketones as well as glucose for energy. Thus, the aim of this study was to determine the metabolism of ketones early after TBI injury in the developing brain. Following the controlled cortical impact injury model of TBI, 21-22-day-old rats were infused with [2,4-13C]β-hydroxybutyrate during the acute (4 h) period after injury. Using ex vivo 13C-NMR spectroscopy, we determined that 13C-β-hydroxybutyrate (13C-BHB) metabolism was increased in both the ipsilateral and contralateral sides of the brain after TBI. Incorporation of the label was significantly higher in glutamate than glutamine, indicating that 13C-BHB metabolism was higher in neurons than astrocytes in both sham and injured brains. Our results show that (i) ketone metabolism was significantly higher in both the ipsilateral and contralateral sides of the injured brain after TBI; (ii) ketones were extensively metabolized by both astrocytes and neurons, albeit higher in neurons; (iii) the pyruvate recycling pathway determined by incorporation of the label from the metabolism of 13C-BHB into lactate was upregulated in the immature brain after TBI.
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9
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Wang Q, Kalathil S, Pornrungroj C, Sahm CD, Reisner E. Bacteria–photocatalyst sheet for sustainable carbon dioxide utilization. Nat Catal 2022. [DOI: 10.1038/s41929-022-00817-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Chen JJ, Uthayakumar B, Hyder F. Mapping oxidative metabolism in the human brain with calibrated fMRI in health and disease. J Cereb Blood Flow Metab 2022; 42:1139-1162. [PMID: 35296177 PMCID: PMC9207484 DOI: 10.1177/0271678x221077338] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Conventional functional MRI (fMRI) with blood-oxygenation level dependent (BOLD) contrast is an important tool for mapping human brain activity non-invasively. Recent interest in quantitative fMRI has renewed the importance of oxidative neuroenergetics as reflected by cerebral metabolic rate of oxygen consumption (CMRO2) to support brain function. Dynamic CMRO2 mapping by calibrated fMRI require multi-modal measurements of BOLD signal along with cerebral blood flow (CBF) and/or volume (CBV). In human subjects this "calibration" is typically performed using a gas mixture containing small amounts of carbon dioxide and/or oxygen-enriched medical air, which are thought to produce changes in CBF (and CBV) and BOLD signal with minimal or no CMRO2 changes. However non-human studies have demonstrated that the "calibration" can also be achieved without gases, revealing good agreement between CMRO2 changes and underlying neuronal activity (e.g., multi-unit activity and local field potential). Given the simpler set-up of gas-free calibrated fMRI, there is evidence of recent clinical applications for this less intrusive direction. This up-to-date review emphasizes technological advances for such translational gas-free calibrated fMRI experiments, also covering historical progression of the calibrated fMRI field that is impacting neurological and neurodegenerative investigations of the human brain.
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Affiliation(s)
- J Jean Chen
- Medical Biophysics, University of Toronto, Toronto, Canada.,Rotman Research Institute, Baycrest, Toronto, Canada
| | - Biranavan Uthayakumar
- Medical Biophysics, University of Toronto, Toronto, Canada.,Sunnybrook Research Institute, Toronto, Canada
| | - Fahmeed Hyder
- Magnetic Resonance Research Center (MRRC), Yale University, New Haven, Connecticut, USA.,Department of Radiology, Yale University, New Haven, Connecticut, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Research Program, Yale University, New Haven, Connecticut, USA.,Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
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11
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He Y, Wang S, Han X, Shen J, Lu Y, Zhao J, Shen C, Qiao L. Photosynthesis of Acetate by Sporomusa ovata-CdS Biohybrid System. ACS APPLIED MATERIALS & INTERFACES 2022; 14:23364-23374. [PMID: 35576621 DOI: 10.1021/acsami.2c01918] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Sporomusa ovata, a typical electroautotrophic microorganism, has been utilized in bioelectrosynthesis for carbon dioxide fixation to multicarbon organic chemicals. However, additional photovoltaic devices are normally needed to convert photo energy to electric energy to power the carbon dioxide fixation, which restricts the overall energy conversion efficiency. Herein, we report Sporomusa ovata-CdS biohybrids for artificial photosynthesis driven by light without any other power source. The quantum yield can reach 16.8 ± 9%, and the active duration time of the system can last for 5 days. During the artificial photosynthesis, carbon dioxide is first reduced to formate and finally converted to acetate via the Wood-Ljungdahl pathway. The carbon dioxide fixation, electron transfer, energy metabolism, and reactive oxygen species damage repair processes in the biohybrid system were characterized by proteomic analysis. Key enzymes, e.g., flavoprotein, ferredoxin, formate-tetrahydrofolate ligase, 5-methyltetrahydrofolate:corrinoid iron-sulfur protein methyltransferase, thioredoxin, and rubrerythrin, were found up-regulated in the biohybrid system. The findings are helpful in understanding the mechanism of the artificial photosynthesis and useful for the development of new biohybrid systems using genetically engineered microbes in the future. The study is expected to boost the development of bioabiotic hybrid system in solar energy harvest.
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Affiliation(s)
- Ying He
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Shurong Wang
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Xinyue Han
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Jiayuan Shen
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Yanwei Lu
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Jinzhi Zhao
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Chengpin Shen
- Shanghai Omicsolution Co., Ltd., Shanghai 200000, China
| | - Liang Qiao
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
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12
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Mandal PK, Guha Roy R, Samkaria A, Maroon JC, Arora Y. In Vivo 13C Magnetic Resonance Spectroscopy for Assessing Brain Biochemistry in Health and Disease. Neurochem Res 2022; 47:1183-1201. [PMID: 35089504 DOI: 10.1007/s11064-022-03538-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 12/27/2022]
Abstract
Magnetic resonance spectroscopy (MRS) is a non-invasive technique that contributes to the elucidation of brain biochemistry. 13C MRS enables the detection of specific neurochemicals and their neuroenergetic correlation with neuronal function. The synergistic outcome of 13C MRS and the infusion of 13C-labeled substrates provide an understanding of neurometabolism and the role of glutamate/gamma-aminobutyric acid (GABA) neurotransmission in diseases, such as Alzheimer's disease, schizophrenia, and bipolar disorder. Moreover, 13C MRS provides a window into the altered flux rate of different pathways, including the tricarboxylic acid cycle (TCA) and the glutamate/glutamine/GABA cycle, in health and in various diseases. Notably, the metabolic flux rate of the TCA cycle often decreases in neurodegenerative diseases. Additionally, 13C MRS can be used to investigate several psychiatric and neurological disorders as it directly reflects the real-time production and alterations of key brain metabolites. This review aims to highlight the chronology, the technological advancements, and the applications of 13C MRS in various brain diseases.
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Affiliation(s)
- Pravat K Mandal
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India.
- Florey Institute of Neuroscience and Mental Health, Melbourne School of Medicine Campus, Melbourne, Australia.
| | - Rimil Guha Roy
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
| | - Avantika Samkaria
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
| | - Joseph C Maroon
- Department of Neurosurgery, University of Pittsburgh Medical School, Pittsburgh, PA, USA
| | - Yashika Arora
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
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13
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Soni ND, Ramesh A, Roy D, Patel AB. Brain energy metabolism in intracerebroventricularly administered streptozotocin mouse model of Alzheimer's disease: A 1H-[ 13C]-NMR study. J Cereb Blood Flow Metab 2021; 41:2344-2355. [PMID: 33657898 PMCID: PMC8393290 DOI: 10.1177/0271678x21996176] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease (AD) is a very common neurodegenerative disorder. Although a majority of the AD cases are sporadic, most of the studies are conducted using transgenic models. Intracerebroventricular (ICV) administered streptozotocin (STZ) animals have been used to explore mechanisms in sporadic AD. In this study, we have investigated memory and neurometabolism of ICV-STZ-administered C57BL6/J mice. The neuronal and astroglial metabolic activity was measured in 1H-[13C]-NMR spectrum of cortical and hippocampal tissue extracts of mice infused with [1,6-13C2]glucose and [2-13C]acetate, respectively. STZ-administered mice exhibited reduced (p = 0.00002) recognition index for memory. The levels of creatine, GABA, glutamate and NAA were reduced (p ≤ 0.04), while that of myo-inositol was increased (p < 0.05) in STZ-treated mice. There was a significant (p ≤ 0.014) reduction in aspartate-C3, glutamate-C4/C3, GABA-C2 and glutamine-C4 labeling from [1,6-13C2]glucose. This resulted in decreased rate of glucose oxidation in the cerebral cortex (0.64 ± 0.05 vs. 0.77 ± 0.05 µmol/g/min, p = 0.0008) and hippocampus (0.60 ± 0.04 vs. 0.73 ± 0.07 µmol/g/min, p = 0.001) of STZ-treated mice, due to similar reductions of glucose oxidation in glutamatergic and GABAergic neurons. Additionally, reduced glutamine-C4 labeling points towards compromised synaptic neurotransmission in STZ-treated mice. These data suggest that the ICV-STZ model exhibits neurometabolic deficits typically observed in AD, and its utility in understanding the mechanism of sporadic AD.
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Affiliation(s)
- Narayan D Soni
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Akila Ramesh
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Dipak Roy
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Anant B Patel
- NMR Microimaging and Spectroscopy, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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14
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Svyatova A, Kozinenko VP, Chukanov NV, Burueva DB, Chekmenev EY, Chen YW, Hwang DW, Kovtunov KV, Koptyug IV. PHIP hyperpolarized [1- 13C]pyruvate and [1- 13C]acetate esters via PH-INEPT polarization transfer monitored by 13C NMR and MRI. Sci Rep 2021; 11:5646. [PMID: 33707497 PMCID: PMC7952547 DOI: 10.1038/s41598-021-85136-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 02/18/2021] [Indexed: 01/31/2023] Open
Abstract
Parahydrogen-induced polarization of 13C nuclei by side-arm hydrogenation (PHIP-SAH) for [1-13C]acetate and [1-13C]pyruvate esters with application of PH-INEPT-type pulse sequences for 1H to 13C polarization transfer is reported, and its efficiency is compared with that of polarization transfer based on magnetic field cycling (MFC). The pulse-sequence transfer approach may have its merits in some applications because the entire hyperpolarization procedure is implemented directly in an NMR or MRI instrument, whereas MFC requires a controlled field variation at low magnetic fields. Optimization of the PH-INEPT-type transfer sequences resulted in 13C polarization values of 0.66 ± 0.04% and 0.19 ± 0.02% for allyl [1-13C]pyruvate and ethyl [1-13C]acetate, respectively, which is lower than the corresponding polarization levels obtained with MFC for 1H to 13C polarization transfer (3.95 ± 0.05% and 0.65 ± 0.05% for allyl [1-13C]pyruvate and ethyl [1-13C]acetate, respectively). Nevertheless, a significant 13C NMR signal enhancement with respect to thermal polarization allowed us to perform 13C MR imaging of both biologically relevant hyperpolarized molecules which can be used to produce useful contrast agents for the in vivo imaging applications.
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Affiliation(s)
- Alexandra Svyatova
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090 ,grid.4605.70000000121896553Novosibirsk State University, 2 Pirogova St., Novosibirsk, Russia 630090 ,grid.418953.2Institute of Cytology and Genetics SB RAS, 10 Ac. Lavrentieva Ave., Novosibirsk, Russia 630090
| | - Vitaly P. Kozinenko
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090 ,grid.4605.70000000121896553Novosibirsk State University, 2 Pirogova St., Novosibirsk, Russia 630090
| | - Nikita V. Chukanov
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090 ,grid.4605.70000000121896553Novosibirsk State University, 2 Pirogova St., Novosibirsk, Russia 630090
| | - Dudari B. Burueva
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090 ,grid.4605.70000000121896553Novosibirsk State University, 2 Pirogova St., Novosibirsk, Russia 630090
| | - Eduard Y. Chekmenev
- grid.254444.70000 0001 1456 7807Department of Chemistry, Wayne State University, Detroit, MI 48201 USA ,grid.254444.70000 0001 1456 7807Karmanos Cancer Institute, Wayne State University, Detroit, MI 48201 USA ,grid.254444.70000 0001 1456 7807Integrative Biosciences, Wayne State University, Detroit, MI 48201 USA ,grid.4886.20000 0001 2192 9124Russian Academy of Sciences, Moscow, Russia 119991
| | - Yu-Wen Chen
- grid.28665.3f0000 0001 2287 1366Institute of Biomedical Sciences, Academia Sinica, Taipei, 115 Taiwan (Republic of China)
| | - Dennis W. Hwang
- grid.28665.3f0000 0001 2287 1366Institute of Biomedical Sciences, Academia Sinica, Taipei, 115 Taiwan (Republic of China)
| | - Kirill V. Kovtunov
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090 ,grid.4605.70000000121896553Novosibirsk State University, 2 Pirogova St., Novosibirsk, Russia 630090
| | - Igor V. Koptyug
- grid.419389.e0000 0001 2163 7228International Tomography Center SB RAS, 3A Institutskaya St., Novosibirsk, Russia 630090
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15
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Goud NS, Bhattacharya A, Joshi RK, Nagaraj C, Bharath RD, Kumar P. Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology. J Med Chem 2021; 64:1223-1259. [PMID: 33499603 DOI: 10.1021/acs.jmedchem.0c01053] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Ahana Bhattacharya
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Raman Kumar Joshi
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
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16
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Voss CM, Andersen JV, Jakobsen E, Siamka O, Karaca M, Maechler P, Waagepetersen HS. AMP-activated protein kinase (AMPK) regulates astrocyte oxidative metabolism by balancing TCA cycle dynamics. Glia 2020; 68:1824-1839. [PMID: 32092215 DOI: 10.1002/glia.23808] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/12/2020] [Accepted: 02/12/2020] [Indexed: 12/14/2022]
Abstract
AMP-activated protein kinase (AMPK) is an important energy sensor located in cells throughout the human body. From the periphery, AMPK is known to be a metabolic master switch controlling the use of energy fuels. The energy sensor is activated when the energy status of the cell is low, initiating energy-producing pathways and deactivating energy-consuming pathways. All brain cells are crucially dependent on energy production for survival, and the availability of energy substrates must be closely regulated. Intriguingly, the role of AMPK in the regulation of brain cell metabolism has been sparsely investigated, particularly in astrocytes. By investigating metabolism of 13 C-labeled energy substrates in acutely isolated hippocampal slices and cultured astrocytes, with subsequent mass spectrometry analysis, we here show that activation of AMPK increases glycolysis as well as the capacity of the TCA cycle, that is, anaplerosis, through the activity of pyruvate carboxylase (PC) in astrocytes. In addition, we demonstrate that AMPK activation leads to augmented astrocytic glutamate oxidation via pyruvate recycling (i.e., cataplerosis). This regulatory mechanism induced by AMPK activation is mediated via glutamate dehydrogenase (GDH) shown in a CNS-specific GDH knockout mouse. Collectively, these findings demonstrate that AMPK regulates TCA cycle dynamics in astrocytes via PC and GDH activity. AMPK functionality has been shown to be hampered in Alzheimer's and Parkinson's disease and our findings may therefore add to the toolbox for discovery of new metabolic drug targets.
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Affiliation(s)
- Caroline M Voss
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Olga Siamka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Melis Karaca
- Department of Cell Physiology and Metabolism, CMU, University of Geneva, Geneva, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, CMU, University of Geneva, Geneva, Switzerland
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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17
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Chinopoulos C, Seyfried TN. Mitochondrial Substrate-Level Phosphorylation as Energy Source for Glioblastoma: Review and Hypothesis. ASN Neuro 2019; 10:1759091418818261. [PMID: 30909720 PMCID: PMC6311572 DOI: 10.1177/1759091418818261] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most common and malignant of the primary adult brain cancers. Ultrastructural and biochemical evidence shows that GBM cells exhibit mitochondrial abnormalities incompatible with energy production through oxidative phosphorylation (OxPhos). Under such conditions, the mitochondrial F0-F1 ATP synthase operates in reverse at the expense of ATP hydrolysis to maintain a moderate membrane potential. Moreover, expression of the dimeric M2 isoform of pyruvate kinase in GBM results in diminished ATP output, precluding a significant ATP production from glycolysis. If ATP synthesis through both glycolysis and OxPhos was impeded, then where would GBM cells obtain high-energy phosphates for growth and invasion? Literature is reviewed suggesting that the succinate-CoA ligase reaction in the tricarboxylic acid cycle can substantiate sufficient ATP through mitochondrial substrate-level phosphorylation (mSLP) to maintain GBM growth when OxPhos is impaired. Production of high-energy phosphates would be supported by glutaminolysis—a hallmark of GBM metabolism—through the sequential conversion of glutamine → glutamate → alpha-ketoglutarate → succinyl CoA → succinate. Equally important, provision of ATP through mSLP would maintain the adenine nucleotide translocase in forward mode, thus preventing the reverse-operating F0-F1 ATP synthase from depleting cytosolic ATP reserves. Because glucose and glutamine are the primary fuels driving the rapid growth of GBM and most tumors for that matter, simultaneous restriction of these two substrates or inhibition of mSLP should diminish cancer viability, growth, and invasion.
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18
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Oyarzabal A, Marin-Valencia I. Synaptic energy metabolism and neuronal excitability, in sickness and health. J Inherit Metab Dis 2019; 42:220-236. [PMID: 30734319 DOI: 10.1002/jimd.12071] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 01/06/2019] [Accepted: 01/30/2019] [Indexed: 12/11/2022]
Abstract
Most of the energy produced in the brain is dedicated to supporting synaptic transmission. Glucose is the main fuel, providing energy and carbon skeletons to the cells that execute and support synaptic function: neurons and astrocytes, respectively. It is unclear, however, how glucose is provided to and used by these cells under different levels of synaptic activity. It is even more unclear how diseases that impair glucose uptake and oxidation in the brain alter metabolism in neurons and astrocytes, disrupt synaptic activity, and cause neurological dysfunction, of which seizures are one of the most common clinical manifestations. Poor mechanistic understanding of diseases involving synaptic energy metabolism has prevented the expansion of therapeutic options, which, in most cases, are limited to symptomatic treatments. To shed light on the intersections between metabolism, synaptic transmission, and neuronal excitability, we briefly review current knowledge of compartmentalized metabolism in neurons and astrocytes, the biochemical pathways that fuel synaptic transmission at resting and active states, and the mechanisms by which disorders of brain glucose metabolism disrupt neuronal excitability and synaptic function and cause neurological disease in the form of epilepsy.
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Affiliation(s)
- Alfonso Oyarzabal
- Synaptic Metabolism Laboratory, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Isaac Marin-Valencia
- Laboratory of Developmental Neurobiology, The Rockefeller University, New York, New York
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19
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Astrocytic pyruvate carboxylation: Status after 35 years. J Neurosci Res 2019; 97:890-896. [DOI: 10.1002/jnr.24402] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/11/2019] [Accepted: 02/05/2019] [Indexed: 12/24/2022]
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20
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Abstract
Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.
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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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21
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Rehni AK, Dave KR. Impact of Hypoglycemia on Brain Metabolism During Diabetes. Mol Neurobiol 2018; 55:9075-9088. [PMID: 29637442 PMCID: PMC6179939 DOI: 10.1007/s12035-018-1044-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/27/2018] [Indexed: 12/24/2022]
Abstract
Diabetes is a metabolic disease afflicting millions of people worldwide. A substantial fraction of world's total healthcare expenditure is spent on treating diabetes. Hypoglycemia is a serious consequence of anti-diabetic drug therapy, because it induces metabolic alterations in the brain. Metabolic alterations are one of the central mechanisms mediating hypoglycemia-related functional changes in the brain. Acute, chronic, and/or recurrent hypoglycemia modulate multiple metabolic pathways, and exposure to hypoglycemia increases consumption of alternate respiratory substrates such as ketone bodies, glycogen, and monocarboxylates in the brain. The aim of this review is to discuss hypoglycemia-induced metabolic alterations in the brain in glucose counterregulation, uptake, utilization and metabolism, cellular respiration, amino acid and lipid metabolism, and the significance of other sources of energy. The present review summarizes information on hypoglycemia-induced metabolic changes in the brain of diabetic and non-diabetic subjects and the manner in which they may affect brain function.
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Affiliation(s)
- Ashish K Rehni
- Cerebral Vascular Disease Research Laboratories, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Neurology, University of Miami Miller School of Medicine, 1420 NW 9th Ave, NRB/203E, Miami, FL, 33136, USA
| | - Kunjan R Dave
- Cerebral Vascular Disease Research Laboratories, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
- Department of Neurology, University of Miami Miller School of Medicine, 1420 NW 9th Ave, NRB/203E, Miami, FL, 33136, USA.
- Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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22
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Palombo M, Shemesh N, Ronen I, Valette J. Insights into brain microstructure from in vivo DW-MRS. Neuroimage 2018; 182:97-116. [DOI: 10.1016/j.neuroimage.2017.11.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 10/09/2017] [Accepted: 11/15/2017] [Indexed: 12/27/2022] Open
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23
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Oligodendrocytes: Development, Physiology and Glucose Metabolism. ADVANCES IN NEUROBIOLOGY 2018; 13:275-294. [PMID: 27885633 DOI: 10.1007/978-3-319-45096-4_10] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The glutamate-glutamine cycle is an outstanding example of how essential neuronal-glial interactions are for brain function. For several decades, this and other metabolic cycles in the brain have only included neurons and astrocytes but not oligodendrocytes, the myelinating cells of the central nervous system (CNS). Recent data revealed that oligodendrocytes are highly metabolically active cells in the brain and, therefore, should not be ignored. Using 13C-labelled glucose in combination with nuclear magnetic resonance spectroscopy (MRS) and/or mass spectrometry (MS) it is possible to characterize metabolic functions in primary oligodendrocyte cultures. Mature rat oligodendrocytes avidly metabolize glucose in the cytosol and pyruvate derived from glucose in mitochondria. Moreover, they seem to have the ability of performing anaplerosis from pyruvate, which might enable them to synthesize metabolites de novo and transfer them to neighbouring cells. All these original findings highlight the importance of investigating oligodendrocyte metabolism separately from that of astrocytes and neurons to be able to discern the roles played by the individual partners. This is of particular importance in the white matter where the number of oligodendrocytes is considerable. The present book chapter provides some background on oligodendrocyte biology and physiology and summarizes the not very extensive information published on glucose metabolism in oligodendrocytes.
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24
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Pichumani K, Mashimo T, Vemireddy V, Ijare OB, Mickey BE, Malloy CR, Marin-Valencia I, Baskin DS, Bachoo RM, Maher EA. Measurement of 13 C turnover into glutamate and glutamine pools in brain tumor patients. FEBS Lett 2017; 591:3548-3554. [PMID: 28963851 DOI: 10.1002/1873-3468.12867] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 09/18/2017] [Indexed: 12/20/2022]
Abstract
Malignant brain tumors are known to utilize acetate as an alternate carbon source in the citric acid cycle for their bioenergetics. 13 C NMR-based isotopomer analysis has been used to measure turnover of 13 C-acetate carbons into glutamate and glutamine pools in tumors. Plasma from the patients infused with [1,2-13 C]acetate further revealed the presence of 13 C isotopomers of glutamine, glucose, and lactate in the circulation that were generated due to metabolism of [1,2-13 C]acetate by peripheral organs. In the tumor cells, [4-13 C] and [3,4-13 C]glutamate and glutamine isotopomers were generated from blood-borne 13 C-labeled glucose and lactate which were formed due to [1,2-13 C[acetate metabolism of peripheral tissues. [4,5-13 C] and [3,4,5-13 C]glutamate and glutamine isotopomers were produced from [1,2-13 C]acetyl-CoA that was derived from direct oxidation of [1,2-13 C] acetate in the tumor. Major portion of C4 13 C fractional enrichment of glutamate (93.3 ± 0.02%) and glutamine (90.9 ± 0.03%) were derived from [1,2-13 C]acetate-derived acetyl-CoA.
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Affiliation(s)
- Kumar Pichumani
- Department of Neurosurgery and Houston Methodist Research Institute, Kenneth R. Peak Brain and Pituitary Tumor Treatment Center at Houston Methodist Hospital, Houston, TX, USA.,Weill Cornell Medical College, New York, NY, USA
| | - Tomoyuki Mashimo
- Simmons Cancer Center, Dallas, TX, USA.,Annette G. Strauss Center for Neuro-Oncology, Dallas, TX, USA
| | - Vamsidhara Vemireddy
- Annette G. Strauss Center for Neuro-Oncology, Dallas, TX, USA.,Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Omkar B Ijare
- Department of Neurosurgery and Houston Methodist Research Institute, Kenneth R. Peak Brain and Pituitary Tumor Treatment Center at Houston Methodist Hospital, Houston, TX, USA
| | - Bruce E Mickey
- Department of Neurological Surgery, UT Southwestern Medical Center, Dallas, TX, USA
| | - Craig R Malloy
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA.,Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA.,Veterans Affairs North Texas HealthCare System, Lancaster, TX, USA
| | - Isaac Marin-Valencia
- Pediatric Brain Disease Laboratory, The Rockefeller University, New York, NY, USA
| | - David S Baskin
- Department of Neurosurgery and Houston Methodist Research Institute, Kenneth R. Peak Brain and Pituitary Tumor Treatment Center at Houston Methodist Hospital, Houston, TX, USA.,Weill Cornell Medical College, New York, NY, USA
| | - Robert M Bachoo
- Simmons Cancer Center, Dallas, TX, USA.,Annette G. Strauss Center for Neuro-Oncology, Dallas, TX, USA.,Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA.,Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Elizabeth A Maher
- Simmons Cancer Center, Dallas, TX, USA.,Annette G. Strauss Center for Neuro-Oncology, Dallas, TX, USA.,Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA.,Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
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25
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Dehghani M, Kunz N, Lanz B, Yoshihara HAI, Gruetter R. Diffusion-weighted MRS of acetate in the rat brain. NMR IN BIOMEDICINE 2017; 30:e3768. [PMID: 28796319 DOI: 10.1002/nbm.3768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 05/04/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Acetate has been proposed as an astrocyte-specific energy substrate for metabolic studies in the brain. The determination of the relative contribution of the intracellular and extracellular compartments to the acetate signal using diffusion-weighted magnetic resonance spectroscopy can provide an insight into the cellular environment and distribution volume of acetate in the brain. In the present study, localized 1 H nuclear magnetic resonance (NMR) spectroscopy employing a diffusion-weighted stimulated echo acquisition mode (STEAM) sequence at an ultra-high magnetic field (14.1 T) was used to investigate the diffusivity characteristics of acetate and N-acetylaspartate (NAA) in the rat brain in vivo during prolonged acetate infusion. The persistence of the acetate resonance in 1 H spectra acquired at very large diffusion weighting indicated restricted diffusion of acetate and was attributed to intracellular spaces. However, the significantly greater diffusion of acetate relative to NAA suggests that a substantial fraction of acetate is located in the extracellular space of the brain. Assuming an even distribution for acetate in intracellular and extracellular spaces, the diffusion properties of acetate yielded a smaller volume of distribution for acetate relative to water and glucose in the rat brain.
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Affiliation(s)
- Masoumeh Dehghani
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Nicolas Kunz
- Centre d'Imagerie BioMédicale (CIBM)-AIT, École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Bernard Lanz
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Hikari A I Yoshihara
- Service de Cardiologie, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratoire d'imagerie fonctionnelle et métabolique (LIFMET), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Centre d'Imagerie BioMédicale (CIBM), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Department of Radiology, Université de Lausanne (UNIL), Lausanne, Switzerland
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26
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Jalloh I, Helmy A, Howe DJ, Shannon RJ, Grice P, Mason A, Gallagher CN, Stovell MG, van der Heide S, Murphy MP, Pickard JD, Menon DK, Carpenter TA, Hutchinson PJ, Carpenter KLH. Focally perfused succinate potentiates brain metabolism in head injury patients. J Cereb Blood Flow Metab 2017; 37:2626-2638. [PMID: 27798266 PMCID: PMC5482384 DOI: 10.1177/0271678x16672665] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Following traumatic brain injury, complex cerebral energy perturbations occur. Correlating with unfavourable outcome, high brain extracellular lactate/pyruvate ratio suggests hypoxic metabolism and/or mitochondrial dysfunction. We investigated whether focal administration of succinate, a tricarboxylic acid cycle intermediate interacting directly with the mitochondrial electron transport chain, could improve cerebral metabolism. Microdialysis perfused disodium 2,3-13C2 succinate (12 mmol/L) for 24 h into nine sedated traumatic brain injury patients' brains, with simultaneous microdialysate collection for ISCUS analysis of energy metabolism biomarkers (nine patients) and nuclear magnetic resonance of 13C-labelled metabolites (six patients). Metabolites 2,3-13C2 malate and 2,3-13C2 glutamine indicated tricarboxylic acid cycle metabolism, and 2,3-13C2 lactate suggested tricarboxylic acid cycle spinout of pyruvate (by malic enzyme or phosphoenolpyruvate carboxykinase and pyruvate kinase), then lactate dehydrogenase-mediated conversion to lactate. Versus baseline, succinate perfusion significantly decreased lactate/pyruvate ratio (p = 0.015), mean difference -12%, due to increased pyruvate concentration (+17%); lactate changed little (-3%); concentrations decreased for glutamate (-43%) (p = 0.018) and glucose (-15%) (p = 0.038). Lower lactate/pyruvate ratio suggests better redox status: cytosolic NADH recycled to NAD+ by mitochondrial shuttles (malate-aspartate and/or glycerol 3-phosphate), diminishing lactate dehydrogenase-mediated pyruvate-to-lactate conversion, and lowering glutamate. Glucose decrease suggests improved utilisation. Direct tricarboxylic acid cycle supplementation with 2,3-13C2 succinate improved human traumatic brain injury brain chemistry, indicated by biomarkers and 13C-labelling patterns in metabolites.
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Affiliation(s)
- Ibrahim Jalloh
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
- Ibrahim Jalloh, University of Cambridge, Department of Clinical Neurosciences, Division of Neurosurgery, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
| | - Adel Helmy
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Duncan J Howe
- Department of Chemistry, University of Cambridge, UK
| | - Richard J Shannon
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Peter Grice
- Department of Chemistry, University of Cambridge, UK
| | - Andrew Mason
- Department of Chemistry, University of Cambridge, UK
| | - Clare N Gallagher
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Calgary, Canada
| | - Matthew G Stovell
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Susan van der Heide
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
| | | | - John D Pickard
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
| | - David K Menon
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
- Division of Anaesthesia, Department of Medicine, University of Cambridge, UK
| | - T Adrian Carpenter
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Peter J Hutchinson
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Keri LH Carpenter
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
- Keri LH Carpenter, University of Cambridge, Department of Clinical Neurosciences, Division of Neurosurgery, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
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27
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L-Carnitine and Acetyl-L-carnitine Roles and Neuroprotection in Developing Brain. Neurochem Res 2017; 42:1661-1675. [PMID: 28508995 DOI: 10.1007/s11064-017-2288-7] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 12/30/2022]
Abstract
L-Carnitine functions to transport long chain fatty acyl-CoAs into the mitochondria for degradation by β-oxidation. Treatment with L-carnitine can ameliorate metabolic imbalances in many inborn errors of metabolism. In recent years there has been considerable interest in the therapeutic potential of L-carnitine and its acetylated derivative acetyl-L-carnitine (ALCAR) for neuroprotection in a number of disorders including hypoxia-ischemia, traumatic brain injury, Alzheimer's disease and in conditions leading to central or peripheral nervous system injury. There is compelling evidence from preclinical studies that L-carnitine and ALCAR can improve energy status, decrease oxidative stress and prevent subsequent cell death in models of adult, neonatal and pediatric brain injury. ALCAR can provide an acetyl moiety that can be oxidized for energy, used as a precursor for acetylcholine, or incorporated into glutamate, glutamine and GABA, or into lipids for myelination and cell growth. Administration of ALCAR after brain injury in rat pups improved long-term functional outcomes, including memory. Additional studies are needed to better explore the potential of L-carnitine and ALCAR for protection of developing brain as there is an urgent need for therapies that can improve outcome after neonatal and pediatric brain injury.
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28
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Rowlands BD, Klugmann M, Rae CD. Acetate metabolism does not reflect astrocytic activity, contributes directly to GABA synthesis, and is increased by silent information regulator 1 activation. J Neurochem 2017; 140:903-918. [PMID: 27925207 DOI: 10.1111/jnc.13916] [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: 07/12/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
[13 C]Acetate is known to label metabolites preferentially in astrocytes rather than neurons and it has consequently been used as a marker for astrocytic activity. Recent discoveries suggest that control of acetate metabolism and its contributions to the synthesis of metabolites in brain is not as simple as first thought. Here, using a Guinea pig brain cortical tissue slice model metabolizing [1-13 C]D-glucose and [1,2-13 C]acetate, we investigated control of acetate metabolism and the degree to which it reflects astrocytic activity. Using a range of [1,2-13 C]acetate concentrations, we found that acetate is a poor substrate for metabolism and will inhibit metabolism of itself and of glucose at concentrations in excess of 2 mmol/L. By activating astrocytes using potassium depolarization, we found that use of [1,2-13 C]acetate to synthesize glutamine decreases significantly under these conditions showing that acetate metabolism does not necessarily reflect astrocytic activity. By blocking synthesis of glutamine using methionine sulfoximine, we found that significant amount of [1,2-13 C]acetate are still incorporated into GABA and its metabolic precursors in neurons, with around 30% of the GABA synthesized from [1,2-13 C]acetate likely to be made directly in neurons rather than from glutamine supplied by astrocytes. Finally, to test whether activity of the acetate metabolizing enzyme acetyl-CoA synthetase is under acetylation control in the brain, we incubated slices with the AceCS1 deacetylase silent information regulator 1 (SIRT1) activator SRT 1720 and showed consequential increased incorporation of [1,2-13 C]acetate into metabolites. Taken together, these data show that acetate metabolism is not directly nor exclusively related to astrocytic metabolic activity, that use of acetate is related to enzyme acetylation and that acetate is directly metabolized to a significant degree in GABAergic neurons. Changes in acetate metabolism should be interpreted as modulation of metabolism through changes in cellular energetic status via altered enzyme acetylation levels rather than simply as an adjustment of glial-neuronal metabolic activity.
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Affiliation(s)
- Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Matthias Klugmann
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, NSW, Australia.,School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
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29
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Cheshkov S, Dimitrov IE, Jakkamsetti V, Good L, Kelly D, Rajasekaran K, DeBerardinis RJ, Pascual JM, Sherry AD, Malloy CR. Oxidation of [U- 13 C]glucose in the human brain at 7T under steady state conditions. Magn Reson Med 2017; 78:2065-2071. [PMID: 28112825 DOI: 10.1002/mrm.26603] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/23/2016] [Accepted: 12/16/2016] [Indexed: 12/24/2022]
Abstract
PURPOSE Disorders of brain energy metabolism and neurotransmitter recycling have been implicated in multiple neurological conditions. 13 C magnetic resonance spectroscopy (13 C MRS) during intravenous administration of 13 C-labeled compounds has been used to measure turnover rates of brain metabolites. This approach, however, requires prolonged infusion inside the magnet. Proton decoupling is typically required but may be difficult to implement with standard equipment. We examined an alternative approach to monitor glucose metabolism in the human brain. METHODS 13 C-enriched glucose was infused in healthy subjects outside the magnet to a steady-state level of 13 C enrichment. Subsequently, the subjects were scanned at 7T for 60 min without 1 H decoupling. Metabolic modeling was used to calculate anaplerosis. RESULTS Biomarkers of energy metabolism and anaplerosis were detected. The glutamate C5 doublet provided information about glucose-derived acetyl-coenzyme A flux into the tricarboxylic acid (TCA) cycle via pyruvate dehydrogenase, and the bicarbonate signal reflected overall TCA cycle activity. The glutamate C1/C5 ratio is sensitive to anaplerosis. CONCLUSION Brain 13 C MRS at 7T provides information about glucose oxidation and anaplerosis without the need of prolonged 13 C infusions inside the scanner and without technical challenges of 1 H decoupling, making it a feasible approach for clinical research. Magn Reson Med 78:2065-2071, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Sergey Cheshkov
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ivan E Dimitrov
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Philips Medical Systems, Cleveland, Ohio, USA
| | - Vikram Jakkamsetti
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Levi Good
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Dorothy Kelly
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Karthik Rajasekaran
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ralph J DeBerardinis
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Juan M Pascual
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,VA North Texas Health Care System, Dallas, Texas, USA
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30
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Lai M, Gruetter R, Lanz B. Progress towards in vivo brain 13C-MRS in mice: Metabolic flux analysis in small tissue volumes. Anal Biochem 2017; 529:229-244. [PMID: 28119064 DOI: 10.1016/j.ab.2017.01.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 01/08/2023]
Abstract
The combination of dynamic 13C MRS data under infusion of 13C-labelled substrates and compartmental models of cerebral metabolism enabled in vivo measurement of metabolic fluxes with a quantitative and distinct determination of cellular-specific activities. The non-invasive nature and the chemical specificity of the 13C dynamic data obtained in those tracer experiments makes it an attractive approach offering unique insights into cerebral metabolism. Genetically engineered mice present a wealth of disease models particularly interesting for the neuroscience community. Nevertheless, in vivo13C NMR studies of the mouse brain are only recently appearing in the field due to the numerous challenges linked to the small mouse brain volume and the difficulty to follow the mouse physiological parameters within the NMR system during the infusion experiment. This review will present the progresses in the quest for a higher in vivo13C signal-to-noise ratio up to the present state of the art techniques, which made it feasible to assess glucose metabolism in different regions of the mouse brain. We describe how experimental results were integrated into suitable compartmental models and how a deep understanding of cerebral metabolism depends on the reliable detection of 13C in the different molecules and carbon positions.
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Affiliation(s)
- Marta Lai
- Laboratory for Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Department of Radiology, University of Geneva, 1205 Geneva, Switzerland; Department of Radiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Bernard Lanz
- Laboratory for Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
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31
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Cerdán S. Twenty-seven Years of Cerebral Pyruvate Recycling. Neurochem Res 2017; 42:1621-1628. [PMID: 28101749 DOI: 10.1007/s11064-017-2173-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/02/2017] [Accepted: 01/02/2017] [Indexed: 10/20/2022]
Abstract
Cerebral pyruvate recycling is a metabolic pathway deriving carbon skeletons and reducing equivalents from mitochondrial oxaloacetate and malate, to the synthesis of mitochondrial and cytosolic pyruvate, lactate and alanine. The pathway allows both, to provide the tricarboxylic acid cycle with pyruvate molecules produced from alternative substrates to glucose and, to generate reducing equivalents necessary for the operation of NADPH requiring processes. At the cellular level, pyruvate recycling involves the activity of malic enzyme, or the combined activities of phosphoenolpyruvate carboxykinase and pyruvate kinase, as well as of those transporters of the inner mitochondrial membrane exchanging the corresponding intermediates. Its cellular localization between the neuronal or astrocytic compartments of the in vivo brain has been controversial, with evidences favoring either a primarily neuronal or glial localizations, more recently accepted to occur in both environments. This review provides a brief history on the detection and characterization of the pathway, its relations with the early developments of cerebral high resolution 13C NMR, and its potential neuroprotective functions under hypoglycemic conditions or ischemic redox stress.
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Affiliation(s)
- Sebastián Cerdán
- Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC/UAM, c/ Arturo Duperier 4, 28029, Madrid, Spain.
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32
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Yip J, Geng X, Shen J, Ding Y. Cerebral Gluconeogenesis and Diseases. Front Pharmacol 2017; 7:521. [PMID: 28101056 PMCID: PMC5209353 DOI: 10.3389/fphar.2016.00521] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 12/15/2016] [Indexed: 01/08/2023] Open
Abstract
The gluconeogenesis pathway, which has been known to normally present in the liver, kidney, intestine, or muscle, has four irreversible steps catalyzed by the enzymes: pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase. Studies have also demonstrated evidence that gluconeogenesis exists in brain astrocytes but no convincing data have yet been found in neurons. Astrocytes exhibit significant 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 activity, a key mechanism for regulating glycolysis and gluconeogenesis. Astrocytes are unique in that they use glycolysis to produce lactate, which is then shuttled into neurons and used as gluconeogenic precursors for reduction. This gluconeogenesis pathway found in astrocytes is becoming more recognized as an important alternative glucose source for neurons, specifically in ischemic stroke and brain tumor. Further studies are needed to discover how the gluconeogenesis pathway is controlled in the brain, which may lead to the development of therapeutic targets to control energy levels and cellular survival in ischemic stroke patients, or inhibit gluconeogenesis in brain tumors to promote malignant cell death and tumor regression. While there are extensive studies on the mechanisms of cerebral glycolysis in ischemic stroke and brain tumors, studies on cerebral gluconeogenesis are limited. Here, we review studies done to date regarding gluconeogenesis to evaluate whether this metabolic pathway is beneficial or detrimental to the brain under these pathological conditions.
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Affiliation(s)
- James Yip
- Department of Neurosurgery, Wayne State University School of Medicine Detroit, MI, USA
| | - Xiaokun Geng
- Department of Neurosurgery, Wayne State University School of MedicineDetroit, MI, USA; China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical UniversityBeijing, China; Department of Neurology, Beijing Luhe Hospital, Capital Medical UniversityBeijing, China
| | - Jiamei Shen
- Department of Neurosurgery, Wayne State University School of MedicineDetroit, MI, USA; China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical UniversityBeijing, China
| | - Yuchuan Ding
- Department of Neurosurgery, Wayne State University School of MedicineDetroit, MI, USA; China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical UniversityBeijing, China
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33
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Zheng H, Zheng Y, Wang D, Cai A, Lin Q, Zhao L, Chen M, Deng M, Ye X, Gao H. Analysis of neuron-astrocyte metabolic cooperation in the brain of db/db mice with cognitive decline using 13C NMR spectroscopy. J Cereb Blood Flow Metab 2017; 37:332-343. [PMID: 26762505 PMCID: PMC5363750 DOI: 10.1177/0271678x15626154] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Revised: 12/01/2015] [Accepted: 12/07/2015] [Indexed: 01/24/2023]
Abstract
Type 2 diabetes has been linked to cognitive impairment, but its potential metabolic mechanism is still unclear. The present study aimed to explore neuron-astrocyte metabolic cooperation in the brain of diabetic (db/db, BKS.Cg-m+/+ Leprdb/J) mice with cognitive decline using 13C NMR technique in combination with intravenous [2-13C]-acetate and [3-13C]-lactate infusions. We found that the 13C-enrichment from [2-13C]-acetate into tricarboxylic acid cycle intermediate, succinate, was significantly decreased in db/db mice with cognitive decline compared with wild-type (WT, C57BLKS/J) mice, while an opposite result was obtained after [3-13C]-lactate infusion. Relative to WT mice, db/db mice with cognitive decline had significantly lower 13C labeling percentages in neurotransmitters including glutamine, glutamate, and γ-aminobutyric acid after [2-13C]-acetate infusion. However, [3-13C]-lactate resulted in increased 13C-enrichments in neurotransmitters in db/db mice with cognitive decline. This may indicate that the disturbance of neurotransmitter metabolism occurred during the development of cognitive decline. In addition, a reduction in 13C-labeling of lactate and an increase in gluconeogenesis were found from both labeled infusions in db/db mice with cognitive decline. Therefore, our results suggest that the development of cognitive decline in type 2 diabetes may be implicated to an unbalanced metabolism in neuron-astrocyte cooperation and an enhancement of gluconeogenesis.
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Affiliation(s)
- Hong Zheng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Yongquan Zheng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China.,Radiology Department of the Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
| | - Dan Wang
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Aimin Cai
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qiuting Lin
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Liangcai Zhao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Minjiang Chen
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Mingjie Deng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xinjian Ye
- Radiology Department of the Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
| | - Hongchang Gao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
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34
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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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35
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Hyperpolarized MRS: New tool to study real-time brain function and metabolism. Anal Biochem 2016; 529:270-277. [PMID: 27665679 DOI: 10.1016/j.ab.2016.09.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 08/31/2016] [Accepted: 09/21/2016] [Indexed: 11/23/2022]
Abstract
The advent of dissolution dynamic nuclear polarization (DNP) led to the emergence of a new kind of magnetic resonance (MR) measurements providing the opportunity to probe metabolism in vivo in real time. It has been shown that, following the injection of hyperpolarized substrates prepared using dissolution DNP, specific metabolic bioprobes that can be used to differentiate between healthy and pathological tissue in preclinical and clinical studies can be readily detected by MR thanks to the tremendous signal enhancement. The present article aims at reviewing the studies of cerebral function and metabolism based on the use of hyperpolarized MR. The constraints and future opportunities that this technology could offer are discussed.
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Valette J, Tiret B, Boumezbeur F. Experimental strategies for in vivo 13C NMR spectroscopy. Anal Biochem 2016; 529:216-228. [PMID: 27515993 DOI: 10.1016/j.ab.2016.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/24/2016] [Accepted: 08/04/2016] [Indexed: 11/15/2022]
Abstract
In vivo carbon-13 (13C) MRS opens unique insights into the metabolism of intact organisms, and has led to major advancements in the understanding of cellular metabolism under normal and pathological conditions in various organs such as skeletal muscles, the heart, the liver and the brain. However, the technique comes at the expense of significant experimental difficulties. In this review we focus on the experimental aspects of non-hyperpolarized 13C MRS in vivo. Some of the enrichment strategies which have been proposed so far are described; the various MRS acquisition paradigms to measure 13C labeling are then presented. Finally, practical aspects of 13C spectral quantification are discussed.
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Affiliation(s)
- Julien Valette
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France.
| | - Brice Tiret
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Fawzi Boumezbeur
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), NeuroSpin, F-91190 Gif-sur-Yvette, France
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Contreras L, Rial E, Cerdan S, Satrustegui J. Uncoupling Protein 2 (UCP2) Function in the Brain as Revealed by the Cerebral Metabolism of (1–13C)-Glucose. Neurochem Res 2016; 42:108-114. [DOI: 10.1007/s11064-016-1999-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 06/30/2016] [Accepted: 07/02/2016] [Indexed: 12/15/2022]
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Llorente-Folch I, Rueda CB, Pardo B, Szabadkai G, Duchen MR, Satrustegui J. The regulation of neuronal mitochondrial metabolism by calcium. J Physiol 2016; 593:3447-62. [PMID: 25809592 DOI: 10.1113/jp270254] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/18/2015] [Indexed: 12/24/2022] Open
Abstract
Calcium signalling is fundamental to the function of the nervous system, in association with changes in ionic gradients across the membrane. Although restoring ionic gradients is energetically costly, a rise in intracellular Ca(2+) acts through multiple pathways to increase ATP synthesis, matching energy supply to demand. Increasing cytosolic Ca(2+) stimulates metabolite transfer across the inner mitochondrial membrane through activation of Ca(2+) -regulated mitochondrial carriers, whereas an increase in matrix Ca(2+) stimulates the citric acid cycle and ATP synthase. The aspartate-glutamate exchanger Aralar/AGC1 (Slc25a12), a component of the malate-aspartate shuttle (MAS), is stimulated by modest increases in cytosolic Ca(2+) and upregulates respiration in cortical neurons by enhancing pyruvate supply into mitochondria. Failure to increase respiration in response to small (carbachol) and moderate (K(+) -depolarization) workloads and blunted stimulation of respiration in response to high workloads (veratridine) in Aralar/AGC1 knockout neurons reflect impaired MAS activity and limited mitochondrial pyruvate supply. In response to large workloads (veratridine), acute stimulation of respiration occurs in the absence of MAS through Ca(2+) influx through the mitochondrial calcium uniporter (MCU) and a rise in matrix [Ca(2+) ]. Although the physiological importance of the MCU complex in work-induced stimulation of respiration of CNS neurons is not yet clarified, abnormal mitochondrial Ca(2+) signalling causes pathology. Indeed, loss of function mutations in MICU1, a regulator of MCU complex, are associated with neuromuscular disease. In patient-derived MICU1 deficient fibroblasts, resting matrix Ca(2+) is increased and mitochondria fragmented. Thus, the fine tuning of Ca(2+) signals plays a key role in shaping mitochondrial bioenergetics.
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Affiliation(s)
- I Llorente-Folch
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid-(CSIC-UAM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.,Instituto de Investigación Sanitaria Fundación Jiménez Díaz IIS-FJD, Madrid, Spain
| | - C B Rueda
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid-(CSIC-UAM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.,Instituto de Investigación Sanitaria Fundación Jiménez Díaz IIS-FJD, Madrid, Spain
| | - B Pardo
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid-(CSIC-UAM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.,Instituto de Investigación Sanitaria Fundación Jiménez Díaz IIS-FJD, Madrid, Spain
| | - G Szabadkai
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London, UK.,Department of Biomedical Sciences, University of Padua and Consiglio Nazionale delle Ricerche Neuroscience Institute, Padua, Italy
| | - M R Duchen
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London, UK
| | - J Satrustegui
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid-(CSIC-UAM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.,Instituto de Investigación Sanitaria Fundación Jiménez Díaz IIS-FJD, Madrid, Spain
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Pichumani K, Mashimo T, Vemireddy V, Kovacs Z, Ratnakar J, Mickey B, Malloy CR, DeBerardinis RJ, Bachoo RM, Maher EA. Hepatic gluconeogenesis influences (13)C enrichment in lactate in human brain tumors during metabolism of [1,2-(13)C]acetate. Neurochem Int 2016; 97:133-6. [PMID: 27020407 DOI: 10.1016/j.neuint.2016.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/21/2016] [Accepted: 03/23/2016] [Indexed: 11/26/2022]
Abstract
(13)C-enriched compounds are readily metabolized in human malignancies. Fragments of the tumor, acquired by biopsy or surgical resection, may be acid-extracted and (13)C NMR spectroscopy of metabolites such as glutamate, glutamine, 2-hydroxyglutarate, lactate and others provide a rich source of information about tumor metabolism in situ. Recently we observed (13)C-(13)C spin-spin coupling in (13)C NMR spectra of lactate in brain tumors removed from patients who were infused with [1,2-(13)C]acetate prior to the surgery. We found, in four patients, that infusion of (13)C-enriched acetate was associated with synthesis of (13)C-enriched glucose, detectable in plasma. (13)C labeled glucose derived from [1,2-(13)C]acetate metabolism in the liver and the brain pyruvate recycling in the tumor together lead to the production of the (13)C labeled lactate pool in the brain tumor. Their combined contribution to acetate metabolism in the brain tumors was less than 4.0%, significantly lower than the direct oxidation of acetate in the citric acid cycle in tumors.
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Affiliation(s)
- Kumar Pichumani
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Tomoyuki Mashimo
- Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Annette G. Strauss Center for Neuro-Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vamsidhara Vemireddy
- Annette G. Strauss Center for Neuro-Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zoltan Kovacs
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - James Ratnakar
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bruce Mickey
- Department of Neurological Surgery, UT Southwestern Medical Center, Dallas, TX 75390, USA; Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Annette G. Strauss Center for Neuro-Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Radiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Veterans Affairs North Texas HealthCare System, Lancaster, TX 75216, USA
| | - Ralph J DeBerardinis
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX 75390, USA; McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, TX 75390, USA; Children's Medical Center Research Institute, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Robert M Bachoo
- Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Annette G. Strauss Center for Neuro-Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Elizabeth A Maher
- Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Annette G. Strauss Center for Neuro-Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA
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Amaral AI, Hadera MG, Tavares JM, Kotter MRN, Sonnewald U. Characterization of glucose-related metabolic pathways in differentiated rat oligodendrocyte lineage cells. Glia 2016; 64:21-34. [PMID: 26352325 PMCID: PMC4832329 DOI: 10.1002/glia.22900] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/22/2015] [Indexed: 12/24/2022]
Abstract
Although oligodendrocytes constitute a significant proportion of cells in the central nervous system (CNS), little is known about their intermediary metabolism. We have, therefore, characterized metabolic functions of primary oligodendrocyte precursor cell cultures at late stages of differentiation using isotope-labelled metabolites. We report that differentiated oligodendrocyte lineage cells avidly metabolize glucose in the cytosol and pyruvate derived from glucose in the mitochondria. The labelling patterns of metabolites obtained after incubation with [1,2-(13)C]glucose demonstrated that the pentose phosphate pathway (PPP) is highly active in oligodendrocytes (approximately 10% of glucose is metabolized via the PPP as indicated by labelling patterns in phosphoenolpyruvate). Mass spectrometry and magnetic resonance spectroscopy analyses of metabolites after incubation of cells with [1-(13)C]lactate or [1,2-(13)C]glucose, respectively, demonstrated that anaplerotic pyruvate carboxylation, which was thought to be exclusive to astrocytes, is also active in oligodendrocytes. Using [1,2-(13)C]acetate, we show that oligodendrocytes convert acetate into acetyl CoA which is metabolized in the tricarboxylic acid cycle. Analysis of labelling patterns of alanine after incubation of cells with [1,2-(13)C]acetate and [1,2-(13)C]glucose showed catabolic oxidation of malate or oxaloacetate. In conclusion, we report that oligodendrocyte lineage cells at late differentiation stages are metabolically highly active cells that are likely to contribute considerably to the metabolic activity of the CNS.
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Affiliation(s)
- Ana I. Amaral
- Anne McLaren LaboratoryWellcome Trust‐Medical Research Council Cambridge Stem Cell Institute and Department of Clinical Neurosciences, University of CambridgeCambridgeCB2 0SZUnited Kingdom
| | - Mussie G. Hadera
- Department of Neuroscience, Faculty of MedicineNorwegian University of Science and TechnologyTrondheim7491Norway
| | - Joana M. Tavares
- Anne McLaren LaboratoryWellcome Trust‐Medical Research Council Cambridge Stem Cell Institute and Department of Clinical Neurosciences, University of CambridgeCambridgeCB2 0SZUnited Kingdom
| | - Mark R. N. Kotter
- Anne McLaren LaboratoryWellcome Trust‐Medical Research Council Cambridge Stem Cell Institute and Department of Clinical Neurosciences, University of CambridgeCambridgeCB2 0SZUnited Kingdom
| | - Ursula Sonnewald
- Department of Neuroscience, Faculty of MedicineNorwegian University of Science and TechnologyTrondheim7491Norway
- Department of Drug Design and Pharmacology, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagen2100Denmark
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A Tribute to Mary C. McKenna: Glutamate as Energy Substrate and Neurotransmitter-Functional Interaction Between Neurons and Astrocytes. Neurochem Res 2015; 42:4-9. [PMID: 26721512 DOI: 10.1007/s11064-015-1813-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/16/2015] [Accepted: 12/18/2015] [Indexed: 10/22/2022]
Abstract
Glutamate metabolism in the brain is extremely complex not only involving a large variety of enzymes but also a tight partnership between neurons and astrocytes, the latter cells being in control of de novo synthesis of glutamate. This review provides an account of the processes involved, i.e. pyruvate carboxylation and recycling as well as the glutamate-glutamine cycle, focusing on the many seminal contributions from Dr. Mary McKenna. The ramification of the astrocytic end feet allowing contact and control of hundreds of thousands of synapses at the same time obviously puts these cells in a prominent position to regulate neural activity. Additionally, the astrocytes take active part in the neurotransmission processes by releasing a variety of gliotransmitters including glutamate. Hence, the term "the tripartite synapse", in which there is an active and dynamic interplay between the pre- and post-synaptic neurons and the ensheathing astrocytes, has been coined. The studies of Mary McKenna and her colleagues over several decades have been of paramount importance for the elucidation of compartmentation in astrocytes and synaptic terminals and the intricate metabolic processes underlying the glutamatergic neurotransmission process.
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Nitzsche R, Zagoriy V, Lucius R, Gupta N. Metabolic Cooperation of Glucose and Glutamine Is Essential for the Lytic Cycle of Obligate Intracellular Parasite Toxoplasma gondii. J Biol Chem 2015; 291:126-41. [PMID: 26518878 DOI: 10.1074/jbc.m114.624619] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 11/06/2022] Open
Abstract
Toxoplasma gondii is a widespread protozoan parasite infecting nearly all warm-blooded organisms. Asexual reproduction of the parasite within its host cells is achieved by consecutive lytic cycles, which necessitates biogenesis of significant energy and biomass. Here we show that glucose and glutamine are the two major physiologically important nutrients used for the synthesis of macromolecules (ATP, nucleic acid, proteins, and lipids) in T. gondii, and either of them is sufficient to ensure the parasite survival. The parasite can counteract genetic ablation of its glucose transporter by increasing the flux of glutamine-derived carbon through the tricarboxylic acid cycle and by concurrently activating gluconeogenesis, which guarantee a continued biogenesis of ATP and biomass for host-cell invasion and parasite replication, respectively. In accord, a pharmacological inhibition of glutaminolysis or oxidative phosphorylation arrests the lytic cycle of the glycolysis-deficient mutant, which is primarily a consequence of impaired invasion due to depletion of ATP. Unexpectedly, however, intracellular parasites continue to proliferate, albeit slower, notwithstanding a simultaneous deprivation of glucose and glutamine. A growth defect in the glycolysis-impaired mutant is caused by a compromised synthesis of lipids, which cannot be counterbalanced by glutamine but can be restored by acetate. Consistently, supplementation of parasite cultures with exogenous acetate can amend the lytic cycle of the glucose transport mutant. Such plasticity in the parasite's carbon flux enables a growth-and-survival trade-off in assorted nutrient milieus, which may underlie the promiscuous survival of T. gondii tachyzoites in diverse host cells. Our results also indicate a convergence of parasite metabolism with cancer cells.
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Affiliation(s)
- Richard Nitzsche
- From the Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany
| | | | - Richard Lucius
- From the Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany
| | - Nishith Gupta
- From the Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany, Parasitology Unit, Max-Planck Institute for Infection Biology, Berlin 10117, Germany
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43
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Olsen GM, Sonnewald U. Glutamate: Where does it come from and where does it go? Neurochem Int 2015; 88:47-52. [DOI: 10.1016/j.neuint.2014.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 10/30/2014] [Accepted: 11/03/2014] [Indexed: 11/15/2022]
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Nissen JD, Pajęcka K, Stridh MH, Skytt DM, Waagepetersen HS. Dysfunctional TCA-Cycle Metabolism in Glutamate Dehydrogenase Deficient Astrocytes. Glia 2015. [DOI: 10.1002/glia.22895] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Jakob D. Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Kamilla Pajęcka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Malin H. Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Dorte M. Skytt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Helle S. Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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Bouzier-Sore AK, Bolaños JP. Uncertainties in pentose-phosphate pathway flux assessment underestimate its contribution to neuronal glucose consumption: relevance for neurodegeneration and aging. Front Aging Neurosci 2015; 7:89. [PMID: 26042035 PMCID: PMC4436897 DOI: 10.3389/fnagi.2015.00089] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/01/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Juan P Bolaños
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC Salamanca, Spain
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Zhang Y, Zhang S, Marin-Valencia I, Puchowicz MA. Decreased carbon shunting from glucose toward oxidative metabolism in diet-induced ketotic rat brain. J Neurochem 2014; 132:301-12. [PMID: 25314677 DOI: 10.1111/jnc.12965] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/27/2014] [Accepted: 10/06/2014] [Indexed: 12/19/2022]
Abstract
The mechanistic link of ketosis to neuroprotection under certain pathological conditions continues to be explored. We investigated whether chronic ketosis induced by ketogenic diet results in the partitioning of ketone bodies toward oxidative metabolism in brain. We hypothesized that diet-induced ketosis results in increased shunting of ketone bodies toward citric acid cycle and amino acids with decreased carbon shunting from glucose. Rats were fed standard (STD) or ketogenic (KG) diets for 3.5 weeks and then infused with [U-(13) C]glucose or [U-(13) C]acetoacetate tracers. Concentrations and (13) C-labeling pattern of citric acid cycle intermediates and amino acids were analyzed from brain homogenates using stable isotopomer mass spectrometry analysis. The contribution of [U-(13) C]glucose to acetyl-CoA and amino acids decreased by ~ 30% in the KG group versus STD, whereas [U-(13) C]acetoacetate contributions were more than two-fold higher. The concentration of GABA remained constant across groups; however, the (13) C labeling of GABA was markedly increased in the KG group infused with [U-(13) C]acetoacetate compared to STD. This study reveals that there is a significant contribution of ketone bodies to oxidative metabolism and GABA in diet-induced ketosis. We propose that this represents a fundamental mechanism of neuroprotection under pathological conditions.
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Affiliation(s)
- Yifan Zhang
- Department of Biomedical Engineering, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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Marin-Valencia I, Hooshyar MA, Pichumani K, Sherry AD, Malloy CR. The ratio of acetate-to-glucose oxidation in astrocytes from a single 13C NMR spectrum of cerebral cortex. J Neurochem 2014; 132:99-109. [PMID: 25231025 DOI: 10.1111/jnc.12948] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/13/2014] [Accepted: 09/15/2014] [Indexed: 11/30/2022]
Abstract
The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate.
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Affiliation(s)
- Isaac Marin-Valencia
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA; Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
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Sonnewald U. Glutamate synthesis has to be matched by its degradation - where do all the carbons go? J Neurochem 2014; 131:399-406. [PMID: 24989463 DOI: 10.1111/jnc.12812] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/24/2014] [Accepted: 06/28/2014] [Indexed: 01/11/2023]
Abstract
The central process in energy production is the oxidation of acetyl-CoA to CO2 by the tricarboxylic acid (TCA, Krebs, citric acid) cycle. However, this cycle functions also as a biosynthetic pathway from which intermediates leave to be converted primarily to glutamate, GABA, glutamine and aspartate and to a smaller extent to glucose derivatives and fatty acids in the brain. When TCA cycle ketoacids are removed, they must be replaced to permit the continued function of this essential pathway, by a process termed anaplerosis. Since the TCA cycle cannot act as a carbon sink, anaplerosis must be coupled with cataplerosis; the exit of intermediates from the TCA cycle. The role of anaplerotic reactions for cellular metabolism in the brain has been studied extensively. However, the coupling of this process with cataplerosis and the roles that both pathways play in the regulation of amino acid, glucose, and fatty acid homeostasis have not been emphasized. The concept of a linkage between anaplerosis and cataplerosis should be underscored, because the balance between these two processes is essential. The hypothesis that cataplerosis in the brain is achieved by exporting the lactate generated from the TCA cycle intermediates into the blood and perivascular area is presented. This shifts the generally accepted paradigm of lactate generation as simply derived from glycolysis to that of oxidation and might present an alternative explanation for aerobic glycolysis. Intermediates leave the tricarboxylic acid cycle and must be replaced by a process termed anaplerosis that must be coupled to cataplerosis. We hypothesize that cataplerosis is achieved by exporting the lactate generated from the cycle into the blood and perivascular area. This shifts the paradigm of lactate generation as solely derived from glycolysis to that of oxidation and might present an alternative explanation for aerobic glycolysis.
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Affiliation(s)
- Ursula Sonnewald
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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Wang N, Zhao LC, Zheng YQ, Dong MJ, Su Y, Chen WJ, Hu ZL, Yang YJ, Gao HC. Alteration of Interaction Between Astrocytes and Neurons in Different Stages of Diabetes: a Nuclear Magnetic Resonance Study Using [1-13C]Glucose and [2-13C]Acetate. Mol Neurobiol 2014; 51:843-52. [DOI: 10.1007/s12035-014-8808-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 07/10/2014] [Indexed: 12/17/2022]
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50
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Abstract
(11)C-acetate PET is used in the assessment of various cardiologic and oncologic diseases. This article describes the physiologic uptake of (11)C-acetate and presents the common benign findings in different anatomic parts of the body. Salivary glands, tonsils, thyroid, meningeal tuberculoma, meningiomas, and macroadenomas of pituitary gland are sites of mild to moderate tracer uptake in the head and neck region. Parenchymal diseases of the lung and reactive and/or inflammatory mediastinal lymphadenopathies cause benign (11)C-acetate uptake in the thorax. Liver, spleen, pancreas, and rectum show an increased uptake. Urinary tract and prostate gland show faint tracer uptake.
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