51
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Zielonka M, Probst J, Carl M, Hoffmann GF, Kölker S, Okun JG. Bioenergetic dysfunction in a zebrafish model of acute hyperammonemic decompensation. Exp Neurol 2019; 314:91-99. [PMID: 30653968 DOI: 10.1016/j.expneurol.2019.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/18/2018] [Accepted: 01/12/2019] [Indexed: 12/30/2022]
Abstract
Acute hyperammonemic encephalopathy is a life-threatening manifestation of individuals with urea cycle disorders, which is associated with high mortality rates and severe neurological sequelae in survivors. Cerebral bioenergetic failure has been proposed as one of the key mechanisms underlying hyperammonemia-induced brain damage, but data supporting this hypothesis remain inconclusive and partially contradictory. Using a previously established zebrafish model of acute hyperammonemic decompensation, we unraveled that acute hyperammonemia leads to a transamination-dependent withdrawal of 2-oxoglutarate (alpha-ketoglutarate) from the tricarboxylic acid (TCA) cycle with consecutive TCA cycle dysfunction, ultimately causing impaired oxidative phosphorylation with ATP shortage, decreased ATP/ADP-ratio and elevated lactate concentrations. Thus, our study supports and extends the hypothesis that cerebral bioenergetic dysfunction is an important pathophysiological hallmark of hyperammonemia-induced neurotoxicity.
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Affiliation(s)
- Matthias Zielonka
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany.
| | - Joris Probst
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Matthias Carl
- Center for Integrative Biology (CIBIO), Laboratory of Translational Neurogenetics, University of Trento, Trento, Italy
| | - Georg Friedrich Hoffmann
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Stefan Kölker
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Jürgen Günther Okun
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
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52
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Hwang JJ, Jiang L, Sanchez Rangel E, Fan X, Ding Y, Lam W, Leventhal J, Dai F, Rothman DL, Mason GF, Sherwin RS. Glycemic Variability and Brain Glucose Levels in Type 1 Diabetes. Diabetes 2019; 68:163-171. [PMID: 30327383 PMCID: PMC6302539 DOI: 10.2337/db18-0722] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
Abstract
The impact of glycemic variability on brain glucose transport kinetics among individuals with type 1 diabetes mellitus (T1DM) remains unclear. Fourteen individuals with T1DM (age 35 ± 4 years; BMI 26.0 ± 1.4 kg/m2; HbA1c 7.6 ± 0.3) and nine healthy control participants (age 32 ± 4; BMI 23.1 ± 0.8; HbA1c 5.0 ± 0.1) wore a continuous glucose monitor (Dexcom) to measure hypoglycemia, hyperglycemia, and glycemic variability for 5 days followed by 1H MRS scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-h glucose clamp (target glucose concentration 220 mg/dL). Hyperglycemic clamps were also performed in a rat model of T1DM to assess regional differences in brain glucose transport and metabolism. Despite a similar change in plasma glucose levels during the hyperglycemic clamp, individuals with T1DM had significantly smaller increments in intracerebral glucose levels (P = 0.0002). Moreover, among individuals with T1DM, the change in brain glucose correlated positively with the lability index (r = 0.67, P = 0.006). Consistent with findings in humans, streptozotocin-treated rats had lower brain glucose levels in the cortex, hippocampus, and striatum compared with control rats. These findings that glycemic variability is associated with brain glucose levels highlight the need for future studies to investigate the impact of glycemic variability on brain glucose kinetics.
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Affiliation(s)
- Janice J Hwang
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Lihong Jiang
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | | | - Xiaoning Fan
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Yuyan Ding
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Wai Lam
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | | | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | - Graeme F Mason
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
- Department of Psychiatry, Yale School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
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53
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Abstract
Proven treatment strategies for obsessive-compulsive disorder (OCD) include pharmacotherapy with serotonin reuptake inhibitors and cognitive behavior therapy (CBT). A significant proportion of patients (25%-30%) fail to respond to these treatment options, necessitating the need for additional treatment options to improve treatment outcomes and quality of life in patients with OCD. Augmentation strategies using various glutamatergic agents have been explored, with diverse outcomes. The aim of this review is to give an overview of the glutamatergic system in the brain with a focus on glutamatergic abnormalities in OCD and to review the existing evidence for various glutamatergic agents used for augmentation.
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Affiliation(s)
- Karthik Sheshachala
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India
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54
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Metabolic Alterations Within the Primary Visual Cortex in Early Open-angle Glaucoma Patients. J Glaucoma 2018; 27:1046-1051. [DOI: 10.1097/ijg.0000000000001098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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55
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Brocka M, Helbing C, Vincenz D, Scherf T, Montag D, Goldschmidt J, Angenstein F, Lippert M. Contributions of dopaminergic and non-dopaminergic neurons to VTA-stimulation induced neurovascular responses in brain reward circuits. Neuroimage 2018; 177:88-97. [DOI: 10.1016/j.neuroimage.2018.04.059] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 04/11/2018] [Accepted: 04/25/2018] [Indexed: 12/24/2022] Open
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56
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Harris T, Azar A, Sapir G, Gamliel A, Nardi-Schreiber A, Sosna J, Gomori JM, Katz-Brull R. Real-time ex-vivo measurement of brain metabolism using hyperpolarized [1- 13C]pyruvate. Sci Rep 2018; 8:9564. [PMID: 29934508 PMCID: PMC6014998 DOI: 10.1038/s41598-018-27747-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 06/11/2018] [Indexed: 12/19/2022] Open
Abstract
The ability to directly monitor in vivo brain metabolism in real time in a matter of seconds using the dissolution dynamic nuclear polarization technology holds promise to aid the understanding of brain physiology in health and disease. However, translating the hyperpolarized signal observed in the brain to cerebral metabolic rates is not straightforward, as the observed in vivo signals reflect also the influx of metabolites produced in the body, the cerebral blood volume, and the rate of transport across the blood brain barrier. We introduce a method to study rapid metabolism of hyperpolarized substrates in the viable rat brain slices preparation, an established ex vivo model of the brain. By retrospective evaluation of tissue motion and settling from analysis of the signal of the hyperpolarized [1-13C]pyruvate precursor, the T1s of the metabolites and their rates of production can be determined. The enzymatic rates determined here are in the range of those determined previously with classical biochemical assays and are in agreement with hyperpolarized metabolite relative signal intensities observed in the rodent brain in vivo.
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Affiliation(s)
- Talia Harris
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Assad Azar
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Gal Sapir
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Ayelet Gamliel
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Atara Nardi-Schreiber
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Jacob Sosna
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - J Moshe Gomori
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel
| | - Rachel Katz-Brull
- Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, 9112001, Israel.
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57
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López-Gambero AJ, Martínez F, Salazar K, Cifuentes M, Nualart F. Brain Glucose-Sensing Mechanism and Energy Homeostasis. Mol Neurobiol 2018; 56:769-796. [PMID: 29796992 DOI: 10.1007/s12035-018-1099-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/25/2018] [Indexed: 01/02/2023]
Abstract
The metabolic and energy state of the organism depends largely on the availability of substrates, such as glucose for ATP production, necessary for maintaining physiological functions. Deregulation in glucose levels leads to the appearance of pathological signs that result in failures in the cardiovascular system and various diseases, such as diabetes, obesity, nephropathy, and neuropathy. Particularly, the brain relies on glucose as fuel for the normal development of neuronal activity. Regions adjacent to the cerebral ventricles, such as the hypothalamus and brainstem, exercise central control in energy homeostasis. These centers house nuclei of neurons whose excitatory activity is sensitive to changes in glucose levels. Determining the different detection mechanisms, the phenotype of neurosecretion, and neural connections involving glucose-sensitive neurons is essential to understanding the response to hypoglycemia through modulation of food intake, thermogenesis, and activation of sympathetic and parasympathetic branches, inducing glucagon and epinephrine secretion and other hypothalamic-pituitary axis-dependent counterregulatory hormones, such as glucocorticoids and growth hormone. The aim of this review focuses on integrating the current understanding of various glucose-sensing mechanisms described in the brain, thereby establishing a relationship between neuroanatomy and control of physiological processes involved in both metabolic and energy balance. This will advance the understanding of increasingly prevalent diseases in the modern world, especially diabetes, and emphasize patterns that regulate and stimulate intake, thermogenesis, and the overall synergistic effect of the neuroendocrine system.
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Affiliation(s)
- A J López-Gambero
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile.,Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain
| | - F Martínez
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - K Salazar
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - M Cifuentes
- Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain.
| | - F Nualart
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile. .,Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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58
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Jelen LA, King S, Mullins PG, Stone JM. Beyond static measures: A review of functional magnetic resonance spectroscopy and its potential to investigate dynamic glutamatergic abnormalities in schizophrenia. J Psychopharmacol 2018; 32:497-508. [PMID: 29368979 DOI: 10.1177/0269881117747579] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Abnormalities of the glutamate system are increasingly implicated in schizophrenia but their exact nature remains unknown. Proton magnetic resonance spectroscopy (1H-MRS), while fundamental in revealing glutamatergic alterations in schizophrenia, has, until recently, been significantly limited and thought to only provide static measures. Functional magnetic resonance spectroscopy (fMRS), which uses sequential scans for dynamic measurement of a range of brain metabolites in activated brain areas, has lately been applied to a variety of task or stimulus conditions, producing interesting insights into neurometabolite responses to neural activation. Here, we summarise the existing 1H-MRS studies of brain glutamate in schizophrenia. We then present a comprehensive review of research studies that have utilised fMRS, and lastly consider how fMRS methods might further the understanding of glutamatergic abnormalities in schizophrenia.
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Affiliation(s)
- Luke A Jelen
- 1 The Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.,2 South London and Maudsley NHS Foundation Trust, UK
| | - Sinead King
- 1 The Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Paul G Mullins
- 3 Bangor Imaging Unit, School of Psychology, Bangor University, Gwynedd, UK
| | - James M Stone
- 1 The Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
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59
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Ding XQ, Maudsley AA, Schweiger U, Schmitz B, Lichtinghagen R, Bleich S, Lanfermann H, Kahl KG. Effects of a 72 hours fasting on brain metabolism in healthy women studied in vivo with magnetic resonance spectroscopic imaging. J Cereb Blood Flow Metab 2018; 38:469-478. [PMID: 28273723 PMCID: PMC5851137 DOI: 10.1177/0271678x17697721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Adaptive response of human brain to stress plays a key role in maintaining health. Knowledge about how stress affects neurometabolism may help to understand adaptive stress responses, and distinguish maladaptation in neuropsychiatric disorders. In this study, neurometabolic responses to fasting stress in healthy women were investigated. Fifteen healthy females were examined for mood and cognition and using whole-brain MR spectroscopic imaging before and immediately after a 72-h fasting. Results were compared to 15 age-matched healthy females who did not taken part in fasting (non-fasting). Maps of the distributions in the brain of N-acetylaspartate (NAA), total choline (tCho), total creatine (tCr), glutamine/glutamate (Glx), and myo-Inositol (mI) were derived. Metabolite concentrations of each brain lobe and cerebellum measured before fasting were compared to those of post-fasting and non-fasting by repeated-measures ANOVA. After fasting, mood scores significantly increased. Glx decreased in all nine brain regions, tCho in eight, NAA in four and tCr in one, with Glx having the greatest change and the frontal lobes being the most affected brain region. In conclusion, fasting directly influences neurometabolism, and the adaptive brain response to maintain energy homeostasis under food deprivation in healthy women is associated with metabolite-selective and region-dependent changes of metabolite contents.
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Affiliation(s)
- Xiao-Qi Ding
- 1 Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Andrew A Maudsley
- 2 Department of Radiology, University of Miami School of Medicine, Miami, FL, USA
| | - Ulrich Schweiger
- 3 Department of Psychiatry and Psychotherapy, University of Lübeck, Germany
| | - Birte Schmitz
- 1 Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | | | - Stefan Bleich
- 5 Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hannover, Germany
| | - Heinrich Lanfermann
- 1 Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Kai G Kahl
- 5 Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hannover, Germany
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60
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Stanley JA, Raz N. Functional Magnetic Resonance Spectroscopy: The "New" MRS for Cognitive Neuroscience and Psychiatry Research. Front Psychiatry 2018; 9:76. [PMID: 29593585 PMCID: PMC5857528 DOI: 10.3389/fpsyt.2018.00076] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 02/23/2018] [Indexed: 01/30/2023] Open
Abstract
Proton magnetic resonance spectroscopy (1H MRS) is a well-established technique for quantifying the brain regional biochemistry in vivo. In most studies, however, the 1H MRS is acquired during rest with little to no constraint on behavior. Measured metabolite levels, therefore, reflect steady-state concentrations whose associations with behavior and cognition are unclear. With the recent advances in MR technology-higher-field MR systems, robust acquisition techniques and sophisticated quantification methods-1H MRS is now experiencing a resurgence. It is sensitive to task-related and pathology-relevant regional dynamic changes in neurotransmitters, including the most ubiquitous among them, glutamate. Moreover, high temporal resolution approaches allow tracking glutamate modulations at a time scale of under a minute during perceptual, motor, and cognitive tasks. The observed task-related changes in brain glutamate are consistent with new metabolic steady states reflecting the neural output driven by shifts in the local excitatory and inhibitory balance on local circuits. Unlike blood oxygen level differences-base functional MRI, this form of in vivo MRS, also known as functional MRS (1H fMRS), yields a more direct measure of behaviorally relevant neural activity and is considerably less sensitive to vascular changes. 1H fMRS enables noninvasive investigations of task-related glutamate changes that are relevant to normal and impaired cognitive performance, and psychiatric disorders. By targeting brain glutamate, this approach taps into putative neural correlates of synaptic plasticity. This review provides a concise survey of recent technological advancements that lay the foundation for the successful use of 1H fMRS in cognitive neuroscience and neuropsychiatry, including a review of seminal 1H fMRS studies, and the discussion of biological significance of task-related changes in glutamate modulation. We conclude with a discussion of the promises, limitations, and outstanding challenges of this new tool in the armamentarium of cognitive neuroscience and psychiatry research.
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Affiliation(s)
- Jeffrey A Stanley
- Department of Psychiatry and Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Naftali Raz
- Department of Psychology, Wayne State University, Detroit, MI, United States.,Institute of Gerontology, Wayne State University, Detroit, MI, United States.,Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
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61
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Özcan E, Çakır T. Genome-Scale Brain Metabolic Networks as Scaffolds for the Systems Biology of Neurodegenerative Diseases: Mapping Metabolic Alterations. ADVANCES IN NEUROBIOLOGY 2018; 21:195-217. [PMID: 30334223 DOI: 10.1007/978-3-319-94593-4_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Systems-based investigation of diseases requires integrated analysis of cellular networks and high-throughput data of gene products. The use of genome-scale metabolic networks for such integration has led to the elucidation of cellular mechanisms for several cell types from microorganisms to plants. It has become easier and cheaper to generate high-throughput data over years in the form of transcriptome, proteome and metabolome. This has tremendously improved the quality and quantity of information extracted from such data enabling the documentation of active pathways and reactions in cell metabolism. A number of omics-based datasets for several neurodegenerative diseases are now available in public repositories. This increases the potential of using genome-scale brain metabolic networks as a scaffold for this type of data to map metabolic alterations for the purpose of elucidating disease mechanisms and for the diagnosis and treatment of such disorders. This chapter first reviews omics data collected for neurodegenerative diseases to map their effect on metabolism. Later, the potential for genome-scale metabolic modeling of such data is reviewed and discussed in light of recently reconstructed brain metabolic networks at genome-scale.
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Affiliation(s)
- Emrah Özcan
- Department of Bioengineering, Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Tunahan Çakır
- Department of Bioengineering, Gebze Technical University, Gebze, Kocaeli, Turkey.
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62
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Chen H, De Feyter HM, Brown PB, Rothman DL, Cai S, de Graaf RA. Comparison of direct 13C and indirect 1H-[ 13C] MR detection methods for the study of dynamic metabolic turnover in the human brain. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 283:33-44. [PMID: 28869920 DOI: 10.1016/j.jmr.2017.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/02/2017] [Accepted: 08/10/2017] [Indexed: 06/07/2023]
Abstract
A wide range of direct 13C and indirect 1H-[13C] MR detection methods exist to probe dynamic metabolic pathways in the human brain. Choosing an optimal detection method is difficult as sequence-specific features regarding spatial localization, broadband decoupling, spectral resolution, power requirements and sensitivity complicate a straightforward comparison. Here we combine density matrix simulations with experimentally determined values for intrinsic 1H and 13C sensitivity, T1 and T2 relaxation and transmit efficiency to allow selection of an optimal 13C MR detection method for a given application and magnetic field. The indirect proton-observed, carbon-edited (POCE) detection method provides the highest accuracy at reasonable RF power deposition both at 4T and 7T. The various polarization transfer methods all have comparable performances, but may become infeasible at 7T due to the high RF power deposition. 2D MR methods have limited value for the metabolites considered (primarily glutamate, glutamine and γ-amino butyric acid (GABA)), but may prove valuable when additional information can be extracted, such as isotopomers or lipid composition. While providing the lowest accuracy, the detection of non-protonated carbons is the simplest to implement with the lowest RF power deposition. The magnetic field homogeneity is one of the most important parameters affecting the detection accuracy for all metabolites and all acquisition methods.
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Affiliation(s)
- Hao Chen
- Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA; Department of Electronic Science, Xiamen University, Xiamen, Fujian, China
| | - Henk M De Feyter
- Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA
| | - Peter B Brown
- Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA
| | - Shuhui Cai
- Department of Electronic Science, Xiamen University, Xiamen, Fujian, China
| | - Robin A de Graaf
- Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA.
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63
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Mishchenko EL, Petrovskaya OV, Mishchenko AM, Petrovskiy ED, Ivanisenko NV, Ivanisenko VA. Integrated mathematical models for describing complex biological processes. Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s0006350917050141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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64
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Li N, Li S, Shen J. High Field In vivo13C Magnetic Resonance Spectroscopy of Brain by Random Radiofrequency Heteronuclear Decoupling and Data Undersampling. FRONTIERS IN PHYSICS 2017; 5:26. [PMID: 29177139 PMCID: PMC5699482 DOI: 10.3389/fphy.2017.00026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In vivo13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo13C-MRS, alkanyl carbons are detected in the spectra range of 10-65 ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH = 125-145 Hz). Two main proton decoupling methods have been developed: broadband stochastic decoupling and coherent composite or adiabatic pulse decoupling (e.g., WALTZ); the latter is widely used because of its efficiency and superb performance under inhomogeneous B1 field. Because the RF power required for proton decoupling increases quadratically with field strength, in vivo13C-MRS using coherent decoupling is often limited to lowmagnetic fields [<=4 Tesla (T)] to keep the local and averaged specific absorption rate (SAR) under the safety guidelines established by the International Electrotechnical Commission (IEC) and the US Food and Drug Administration (FDA). Alternately, carboxylic/amide carbons are coupled to protons via weak long-range 1H-13C scalar couplings, which can be decoupled using low RF power broadband stochastic decoupling. Recently, the carboxylic/amide 13C-MRS technique using low power random RF heteronuclear decoupling was safely applied to human brain studies at 7T. Here, we review the two major decoupling methods and the carboxylic/amide 13C-MRS with low power decoupling strategy. Further decreases in RF power deposition by frequency-domain windowing and time-domain random under-sampling are also discussed. Low RF power decoupling opens the possibility of performing in vivo13C experiments of human brain at very high magnetic fields (such as 11.7T), where signal-to-noise ratio as well as spatial and temporal spectral resolution are more favorable than lower fields.
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65
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Weatherly CA, Du S, Parpia C, Santos PT, Hartman AL, Armstrong DW. d-Amino Acid Levels in Perfused Mouse Brain Tissue and Blood: A Comparative Study. ACS Chem Neurosci 2017; 8:1251-1261. [PMID: 28206740 DOI: 10.1021/acschemneuro.6b00398] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The l-enantiomer is the predominant type of amino acid in all living systems. However, d-amino acids, once thought to be "unnatural", have been found to be indigenous even in mammalian systems and increasingly appear to be functioning in essential biological and neurological roles. Both d- and l-amino acid levels in the hippocampus, cortex, and blood samples from NIH Swiss mice are reported. Perfused brain tissues were analyzed for the first time, thereby eliminating artifacts due to endogenous blood, and decreased the mouse-to-mouse variability in amino acid levels. Total amino acid levels (l- plus d-enantiomers) in brain tissue are up to 10 times higher than in blood. However, all measured d-amino acid levels in brain tissue are typically ∼10 to 2000 times higher than blood levels. There was a 13% reduction in almost all measured d-amino acid levels in the cortex compared to those in the hippocampus. There is an approximate inverse relationship between the prevalence of an amino acid and the percentage of its d-enantiomeric form. Interestingly, glutamic acid, unlike all other amino acids, had no quantifiable level of its d-antipode. The bioneurological reason for the unique and conspicuous absence/removal of this d-amino acid is yet unknown. However, results suggest that d-glutamate metabolism is likely a unidirectional process and not a cycle, as per the l-glutamate/glutamine cycle. The results suggest that there might be unreported d-amino acid racemases in mammalian brains. The regulation and function of specific other d-amino acids are discussed.
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Affiliation(s)
- Choyce A. Weatherly
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Siqi Du
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Curran Parpia
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Polan T. Santos
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
| | - Adam L. Hartman
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, United States
- Department of Molecular Microbiology and Immunology, Johns Hopkins Blomberg School of Public Health, Baltimore, Maryland 21205, United States
| | - Daniel W. Armstrong
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
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66
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Sonnay S, Gruetter R, Duarte JMN. How Energy Metabolism Supports Cerebral Function: Insights from 13C Magnetic Resonance Studies In vivo. Front Neurosci 2017; 11:288. [PMID: 28603480 PMCID: PMC5445183 DOI: 10.3389/fnins.2017.00288] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/04/2017] [Indexed: 12/25/2022] Open
Abstract
Cerebral function is associated with exceptionally high metabolic activity, and requires continuous supply of oxygen and nutrients from the blood stream. Since the mid-twentieth century the idea that brain energy metabolism is coupled to neuronal activity has emerged, and a number of studies supported this hypothesis. Moreover, brain energy metabolism was demonstrated to be compartmentalized in neurons and astrocytes, and astrocytic glycolysis was proposed to serve the energetic demands of glutamatergic activity. Shedding light on the role of astrocytes in brain metabolism, the earlier picture of astrocytes being restricted to a scaffold-associated function in the brain is now out of date. With the development and optimization of non-invasive techniques, such as nuclear magnetic resonance spectroscopy (MRS), several groups have worked on assessing cerebral metabolism in vivo. In this context, 1H MRS has allowed the measurements of energy metabolism-related compounds, whose concentrations can vary under different brain activation states. 1H-[13C] MRS, i.e., indirect detection of signals from 13C-coupled 1H, together with infusion of 13C-enriched glucose has provided insights into the coupling between neurotransmission and glucose oxidation. Although these techniques tackle the coupling between neuronal activity and metabolism, they lack chemical specificity and fail in providing information on neuronal and glial metabolic pathways underlying those processes. Currently, the improvement of detection modalities (i.e., direct detection of 13C isotopomers), the progress in building adequate mathematical models along with the increase in magnetic field strength now available render possible detailed compartmentalized metabolic flux characterization. In particular, direct 13C MRS offers more detailed dataset acquisitions and provides information on metabolic interactions between neurons and astrocytes, and their role in supporting neurotransmission. Here, we review state-of-the-art MR methods to study brain function and metabolism in vivo, and their contribution to the current understanding of how astrocytic energy metabolism supports glutamatergic activity and cerebral function. In this context, recent data suggests that astrocytic metabolism has been underestimated. Namely, the rate of oxidative metabolism in astrocytes is about half of that in neurons, and it can increase as much as the rate of neuronal metabolism in response to sensory stimulation.
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Affiliation(s)
- Sarah Sonnay
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland.,Department of Radiology, University of LausanneLausanne, Switzerland.,Department of Radiology, University of GenevaGeneva, Switzerland
| | - João M N Duarte
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de LausanneLausanne, Switzerland
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67
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Schcolnik-Cabrera A, Chávez-Blanco A, Domínguez-Gómez G, Dueñas-González A. Understanding tumor anabolism and patient catabolism in cancer-associated cachexia. Am J Cancer Res 2017; 7:1107-1135. [PMID: 28560061 PMCID: PMC5446478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/03/2017] [Indexed: 06/07/2023] Open
Abstract
Cachexia is a multifactorial paraneoplastic syndrome commonly associated with advanced stages of cancer. Cachexia is responsible for poor responses to antitumoral treatment and death in close to one-third of affected patients. There is still an incomplete understanding of the metabolic dysregulation induced by a tumor that leads to the appearance and persistence of cachexia. Furthermore, cachexia is irreversible, and there are currently no guidelines for its diagnosis or treatments for it. In this review, we aim to discuss the current knowledge about cancer-associated cachexia, starting with generalities about cancer as the generator of this syndrome, then analyzing the characteristics of cachexia at the biochemical and metabolic levels in both the tumor and the patient, and finally discussing current therapeutic approaches to treating cancer-associated cachexia.
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Affiliation(s)
| | | | | | - Alfonso Dueñas-González
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas UNAM/Instituto Nacional de CancerologíaMexico
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68
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Ip IB, Berrington A, Hess AT, Parker AJ, Emir UE, Bridge H. Combined fMRI-MRS acquires simultaneous glutamate and BOLD-fMRI signals in the human brain. Neuroimage 2017; 155:113-119. [PMID: 28433623 PMCID: PMC5519502 DOI: 10.1016/j.neuroimage.2017.04.030] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/12/2017] [Accepted: 04/13/2017] [Indexed: 01/29/2023] Open
Abstract
Combined fMRI-MRS is a novel method to non-invasively investigate functional activation in the human brain using simultaneous acquisition of hemodynamic and neurochemical measures. The aim of the current study was to quantify neural activity using combined fMRI-MRS at 7 T. BOLD-fMRI and semi-LASER localization MRS data were acquired from the visual cortex of 13 participants during short blocks (64 s) of flickering checkerboards. We demonstrate a correlation between glutamate and BOLD-fMRI time courses (R=0.381, p=0.031). In addition, we show increases in BOLD-fMRI (1.43±0.17%) and glutamate concentrations (0.15±0.05 I.U., ~2%) during visual stimulation. In contrast, we observed no change in glutamate concentrations in resting state MRS data during sham stimulation periods. Spectral line width changes generated by the BOLD-response were corrected using line broadening. In summary, our results establish the feasibility of concurrent measurements of BOLD-fMRI and neurochemicals using a novel combined fMRI-MRS sequence. Our findings strengthen the link between glutamate and functional activity in the human brain by demonstrating a significant correlation of BOLD-fMRI and glutamate over time, and by showing ~2% glutamate increases during 64 s of visual stimulation. Our tool may become useful for studies characterizing functional dynamics between neurochemicals and hemodynamics in health and disease. Novel MRI sequence measures hemodynamics and neurochemistry in same TR. Stimulation block duration relevant for functional experiments (64s). BOLD-fMRI and glutamate time courses correlate during functional stimulation. Visual stimulation increases glutamate concentrations. Useful to study fundamental relationship between hemodynamics and neurochemistry.
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Affiliation(s)
- I Betina Ip
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxfordshire OX1 3PT, UK; Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, Oxfordshire OX3 9DU, UK.
| | - Adam Berrington
- Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, Oxfordshire OX3 9DU, UK
| | - Aaron T Hess
- Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Oxford, Oxfordshire OX3 9DU, UK
| | - Andrew J Parker
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxfordshire OX1 3PT, UK
| | - Uzay E Emir
- Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, Oxfordshire OX3 9DU, UK
| | - Holly Bridge
- Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, Oxfordshire OX3 9DU, UK
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69
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Becerra-Calixto A, Cardona-Gómez GP. The Role of Astrocytes in Neuroprotection after Brain Stroke: Potential in Cell Therapy. Front Mol Neurosci 2017; 10:88. [PMID: 28420961 PMCID: PMC5376556 DOI: 10.3389/fnmol.2017.00088] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 03/14/2017] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are commonly involved in negative responses through their hyperreactivity and glial scar formation in excitotoxic and/or mechanical injuries. But, astrocytes are also specialized glial cells of the nervous system that perform multiple homeostatic functions for the survival and maintenance of the neurovascular unit. Astrocytes have neuroprotective, angiogenic, immunomodulatory, neurogenic, and antioxidant properties and modulate synaptic function. This makes them excellent candidates as a source of neuroprotection and neurorestoration in tissues affected by ischemia/reperfusion, when some of their deregulated genes can be controlled. Therefore, this review analyzes pro-survival responses of astrocytes that would allow their use in cell therapy strategies.
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Affiliation(s)
| | - Gloria P. Cardona-Gómez
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, School of Medicine, Sede de Investigación Universitaria (SIU), University of AntioquiaMedellín, Colombia
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70
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Functional dynamics of hippocampal glutamate during associative learning assessed with in vivo 1H functional magnetic resonance spectroscopy. Neuroimage 2017; 153:189-197. [PMID: 28363835 DOI: 10.1016/j.neuroimage.2017.03.051] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/06/2017] [Accepted: 03/22/2017] [Indexed: 12/25/2022] Open
Abstract
fMRI has provided vibrant characterization of regional and network responses associated with associative learning and memory; however, their relationship to functional neurochemistry is unclear. Here, we introduce a novel application of in vivo proton functional magnetic resonance spectroscopy (1H fMRS) to investigate the dynamics of hippocampal glutamate during paired-associated learning and memory in healthy young adults. We show that the temporal dynamics of glutamate differed significantly during processes of memory consolidation and retrieval. Moreover, learning proficiency was predictive of the temporal dynamics of glutamate such that fast learners were characterized by a significant increase in glutamate levels early in learning, whereas this increase was only observed later in slow learners. The observed functional dynamics of glutamate provides a novel in vivo marker of brain function. Previously demonstrated N-methyl-D-aspartate (NMDA) receptor mediated synaptic plasticity during associative memory formation may be expressed in glutamate dynamics, which the novel application of 1H MRS is sensitive to. The novel application of 1H fMRS can provide highly innovative vistas for characterizing brain function in vivo, with significant implications for studying glutamatergic neurotransmission in health and disorders such as schizophrenia.
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71
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Martín-Jiménez CA, Salazar-Barreto D, Barreto GE, González J. Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network. Front Aging Neurosci 2017; 9:23. [PMID: 28243200 PMCID: PMC5303712 DOI: 10.3389/fnagi.2017.00023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/27/2017] [Indexed: 12/22/2022] Open
Abstract
Astrocytes are the most abundant cells of the central nervous system; they have a predominant role in maintaining brain metabolism. In this sense, abnormal metabolic states have been found in different neuropathological diseases. Determination of metabolic states of astrocytes is difficult to model using current experimental approaches given the high number of reactions and metabolites present. Thus, genome-scale metabolic networks derived from transcriptomic data can be used as a framework to elucidate how astrocytes modulate human brain metabolic states during normal conditions and in neurodegenerative diseases. We performed a Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network with the purpose of elucidating a significant portion of the metabolic map of the astrocyte. This is the first global high-quality, manually curated metabolic reconstruction network of a human astrocyte. It includes 5,007 metabolites and 5,659 reactions distributed among 8 cell compartments, (extracellular, cytoplasm, mitochondria, endoplasmic reticle, Golgi apparatus, lysosome, peroxisome and nucleus). Using the reconstructed network, the metabolic capabilities of human astrocytes were calculated and compared both in normal and ischemic conditions. We identified reactions activated in these two states, which can be useful for understanding the astrocytic pathways that are affected during brain disease. Additionally, we also showed that the obtained flux distributions in the model, are in accordance with literature-based findings. Up to date, this is the most complete representation of the human astrocyte in terms of inclusion of genes, proteins, reactions and metabolic pathways, being a useful guide for in-silico analysis of several metabolic behaviors of the astrocyte during normal and pathologic states.
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Affiliation(s)
- Cynthia A Martín-Jiménez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
| | - Diego Salazar-Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad JaverianaBogotá, Colombia; Instituto de Ciencias Biomédicas, Universidad Autónoma de ChileSantiago, Chile
| | - Janneth González
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
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72
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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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73
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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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74
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Li N, Li S, Shen J. Reconstruction of randomly under-sampled spectra for in vivo 13C magnetic resonance spectroscopy. Magn Reson Imaging 2016; 37:216-221. [PMID: 27939434 DOI: 10.1016/j.mri.2016.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 12/02/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE Over the past decade, many techniques have been developed to reduce radiofrequency (RF) power deposition associated with proton decoupling in in vivo Carbon-13 (13C) magnetic resonance spectroscopy (MRS). In this work we propose a new strategy that uses data under-sampling to achieve reduction in RF power deposition. MATERIALS AND METHODS Essentially, proton decoupling is required only during randomly selected segments of data acquisition. By taking advantage of the sparse spectral pattern of the carboxylic/amide region of in vivo13C spectra of brain, we developed an iterative algorithm to reconstruct spectra from randomly under-sampled data. Fully sampled data were used as references. Reconstructed spectra were compared with the fully sampled references and evaluated using residuals and relative signal intensity errors. RESULTS Numerical simulations and in vivo experiments at 7Tesla demonstrated that this novel decoupling and data processing strategy can effectively reduce decoupling power deposition by greater than 30%. CONCLUSION This study proposes and evaluates a novel approach to acquire 13C data with reduced proton decoupling power deposition and reconstruct in vivo13C spectra of carboxylic/amide metabolite signals using randomly under-sampled data. Because proton decoupling is not needed over a significant portion of data acquisition, this novel approach can effectively reduce the required decoupling power and thus SAR. It opens the possibility of performing in vivo13C experiments of human brain at very high magnetic fields.
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Affiliation(s)
- Ningzhi Li
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
| | - Shizhe Li
- Magnetic Resonance Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Jun Shen
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA; Magnetic Resonance Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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75
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In vivo N-15 MRS study of glutamate metabolism in the rat brain. Anal Biochem 2016; 529:179-192. [PMID: 27580850 DOI: 10.1016/j.ab.2016.08.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 01/05/2023]
Abstract
In vivo 15N MRS has made a unique contribution to kinetic studies of the individual pathways that control glutamate flux in the rat brain. This review covers the following topics: (1) the advantages and limitations of in vivo 15N MRS and its indirect detection through coupled 1H; (2) kinetic methods; (3) major findings from our and other laboratories in the areas: (a) the uptake of the neurotransmitter glutamate from the extracellular fluid into glia; (b) the metabolism of glutamate to glutamine; (c) glutamine transport to the extracellular fluid; (d) hydrolysis of neuronal glutamine to glutamate; and (e) contribution of transamination from leucine to replenish the glutamate nitrogen. In vivo glutamine synthetase activities measured at several levels of hyperammonemia showed that this enzyme becomes saturated at blood ammonia concentration >0.9 μmol/g, and causes the elevation of brain ammonia. Implications of the results for the cause of hyperammonemic encephalopathy are discussed. Leucine provides >25% of glutamate nitrogen. An intriguing possibility that supplementing leucine may restore cognitive function after brain injury is discussed. Finally, some characteristics of 15N MRS that may facilitate the future application of this technique to the study of the human brain at 4 or 7 T are described.
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76
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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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Weltin A, Kieninger J, Urban GA. Microfabricated, amperometric, enzyme-based biosensors for in vivo applications. Anal Bioanal Chem 2016; 408:4503-21. [PMID: 26935934 PMCID: PMC4909808 DOI: 10.1007/s00216-016-9420-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 02/08/2016] [Accepted: 02/12/2016] [Indexed: 01/19/2023]
Abstract
Miniaturized electrochemical in vivo biosensors allow the measurement of fast extracellular dynamics of neurotransmitter and energy metabolism directly in the tissue. Enzyme-based amperometric biosensing is characterized by high specificity and precision as well as high spatial and temporal resolution. Aside from glucose monitoring, many systems have been introduced mainly for application in the central nervous system in animal models. We compare the microsensor principle with other methods applied in biomedical research to show advantages and drawbacks. Electrochemical sensor systems are easily miniaturized and fabricated by microtechnology processes. We review different microfabrication approaches for in vivo sensor platforms, ranging from simple modified wires and fibres to fully microfabricated systems on silicon, ceramic or polymer substrates. The various immobilization methods for the enzyme such as chemical cross-linking and entrapment in polymer membranes are discussed. The resulting sensor performance is compared in detail. We also examine different concepts to reject interfering substances by additional membranes, aspects of instrumentation and biocompatibility. Practical considerations are elaborated, and conclusions for future developments are presented. Graphical Abstract ᅟ.
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Affiliation(s)
- Andreas Weltin
- Laboratory for Sensors, Department of Microsystems Engineering – IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Jochen Kieninger
- Laboratory for Sensors, Department of Microsystems Engineering – IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Gerald A. Urban
- Laboratory for Sensors, Department of Microsystems Engineering – IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
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78
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Aubrey KR. Presynaptic control of inhibitory neurotransmitter content in VIAAT containing synaptic vesicles. Neurochem Int 2016; 98:94-102. [PMID: 27296116 DOI: 10.1016/j.neuint.2016.06.002] [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: 01/31/2016] [Revised: 05/21/2016] [Accepted: 06/07/2016] [Indexed: 12/13/2022]
Abstract
In mammals, fast inhibitory neurotransmission is carried out by two amino acid transmitters, γ-aminobutyric acid (GABA) and glycine. The higher brain uses only GABA, but in the spinal cord and brain stem both GABA and glycine act as inhibitory signals. In some cases GABA and glycine are co-released from the same neuron where they are co-packaged into synaptic vesicles by a shared vesicular inhibitory amino acid transporter, VIAAT (also called vGAT). The vesicular content of all other classical neurotransmitters (eg. glutamate, monoamines, acetylcholine) is determined by the presence of a specialized vesicular transporter. Because VIAAT is non-specific, the phenotype of inhibitory synaptic vesicles is instead predicted to be dependent on the relative concentration of GABA and glycine in the cytosol of the presynaptic terminal. This predicts that changes in GABA or glycine supply should be reflected in vesicle transmitter content but as yet, the mechanisms that control GABA versus glycine uptake into synaptic vesicles and their potential for modulation are not clearly understood. This review summarizes the most relevant experimental data that examines the link between GABA and glycine accumulation in the presynaptic cytosol and the inhibitory vesicle phenotype. The accumulated evidence challenges the hypothesis that vesicular phenotype is determined simply by the competition of inhibitory transmitter for VIAAT and instead suggest that the GABA/glycine balance in vesicles is dynamically regulated.
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Affiliation(s)
- Karin R Aubrey
- Pain Management Research Institute, Kolling Institute of Medical Research & Northern Clinical School, University of Sydney at Royal North Shore Hospital, Pacific Hwy, St Leonards, NSW, 2065, Australia.
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Allen E, Miéville P, Warren CM, Saghafinia S, Li L, Peng MW, Hanahan D. Metabolic Symbiosis Enables Adaptive Resistance to Anti-angiogenic Therapy that Is Dependent on mTOR Signaling. Cell Rep 2016; 15:1144-60. [PMID: 27134166 PMCID: PMC4872464 DOI: 10.1016/j.celrep.2016.04.029] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 01/28/2016] [Accepted: 04/07/2016] [Indexed: 01/01/2023] Open
Abstract
Therapeutic targeting of tumor angiogenesis with VEGF inhibitors results in demonstrable, but transitory efficacy in certain human tumors and mouse models of cancer, limited by unconventional forms of adaptive/evasive resistance. In one such mouse model, potent angiogenesis inhibitors elicit compartmental reorganization of cancer cells around remaining blood vessels. The glucose and lactate transporters GLUT1 and MCT4 are induced in distal hypoxic cells in a HIF1α-dependent fashion, indicative of glycolysis. Tumor cells proximal to blood vessels instead express the lactate transporter MCT1, and p-S6, the latter reflecting mTOR signaling. Normoxic cancer cells import and metabolize lactate, resulting in upregulation of mTOR signaling via glutamine metabolism enhanced by lactate catabolism. Thus, metabolic symbiosis is established in the face of angiogenesis inhibition, whereby hypoxic cancer cells import glucose and export lactate, while normoxic cells import and catabolize lactate. mTOR signaling inhibition disrupts this metabolic symbiosis, associated with upregulation of the glucose transporter GLUT2. Angiogenesis inhibitors causing acute hypoxia elicit metabolic compartmentalization Hypoxic cancer cells import and metabolize glucose, secreting lactate Normoxic vessel-proximal cancer cells import and metabolize lactate, involving mTOR Co-inhibiting mTOR disrupts the metabolic symbiosis
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Affiliation(s)
- Elizabeth Allen
- The Swiss Institute for Experimental Cancer Research (ISREC), EPFL SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Pascal Miéville
- The Institute of Chemical Sciences and Engineering (ISIC-SB-EPFL), Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC-Direction, CH A3 398 Station 6, 1015 Lausanne, Switzerland
| | - Carmen M Warren
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - Sadegh Saghafinia
- The Swiss Institute for Experimental Cancer Research (ISREC), EPFL SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Leanne Li
- The Swiss Institute for Experimental Cancer Research (ISREC), EPFL SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Mei-Wen Peng
- The Swiss Institute for Experimental Cancer Research (ISREC), EPFL SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Douglas Hanahan
- The Swiss Institute for Experimental Cancer Research (ISREC), EPFL SV ISREC, Station 19, 1015 Lausanne, Switzerland; The Swiss Cancer Center Lausanne (SCCL), Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland.
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80
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Li S, An L, Yu S, Araneta MF, Johnson CS, Wang S, Shen J. (13)C MRS of human brain at 7 Tesla using [2-(13)C]glucose infusion and low power broadband stochastic proton decoupling. Magn Reson Med 2016; 75:954-61. [PMID: 25917936 PMCID: PMC4624052 DOI: 10.1002/mrm.25721] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/12/2015] [Accepted: 03/12/2015] [Indexed: 11/05/2022]
Abstract
PURPOSE Carbon-13 ((13)C) MR spectroscopy (MRS) of the human brain at 7 Tesla (T) may pose patient safety issues due to high radiofrequency (RF) power deposition for proton decoupling. The purpose of present work is to study the feasibility of in vivo (13)C MRS of human brain at 7 T using broadband low RF power proton decoupling. METHODS Carboxylic/amide (13)C MRS of human brain by broadband stochastic proton decoupling was demonstrated on a 7 T scanner. RF safety was evaluated using the finite-difference time-domain method. (13)C signal enhancement by nuclear Overhauser effect (NOE) and proton decoupling was evaluated in both phantoms and in vivo. RESULTS At 7 T, the peak amplitude of carboxylic/amide (13)C signals was increased by a factor of greater than 4 due to the combined effects of NOE and proton decoupling. The 7 T (13)C MRS technique used decoupling power and average transmit power of less than 35 watts (W) and 3.6 W, respectively. CONCLUSION In vivo (13)C MRS studies of human brain can be performed at 7 T, well below the RF safety threshold, by detecting carboxylic/amide carbons with broadband stochastic proton decoupling.
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Affiliation(s)
- Shizhe Li
- Magnetic Resonance Spectroscopy Core Facility, National Institute
of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Li An
- Molecular Imaging Branch, National Institute of Mental Health,
National Institutes of Health, Bethesda, MD, USA
| | - Shao Yu
- Department of Electrical and Computer Engineering, Auburn
University, Auburn, AL, USA
| | - Maria Ferraris Araneta
- Molecular Imaging Branch, National Institute of Mental Health,
National Institutes of Health, Bethesda, MD, USA
| | - Christopher S. Johnson
- Molecular Imaging Branch, National Institute of Mental Health,
National Institutes of Health, Bethesda, MD, USA
| | - Shumin Wang
- Department of Electrical and Computer Engineering, Auburn
University, Auburn, AL, USA
| | - Jun Shen
- Magnetic Resonance Spectroscopy Core Facility, National Institute
of Mental Health, National Institutes of Health, Bethesda, MD, USA
- Molecular Imaging Branch, National Institute of Mental Health,
National Institutes of Health, Bethesda, MD, USA
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81
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Abstract
Mammalian glutaminases catalyze the stoichiometric conversion of L-glutamine to L-glutamate and ammonium ions. In brain, glutaminase is considered the prevailing pathway for synthesis of the neurotransmitter pool of glutamate. Besides neurotransmission, the products of glutaminase reaction also fulfill crucial roles in energy and metabolic homeostasis in mammalian brain. In the last years, new functional roles for brain glutaminases are being uncovered by using functional genomic and proteomic approaches. Glutaminases may act as multifunctional proteins able to perform different tasks: the discovery of multiple transcript variants in neurons and glial cells, novel extramitochondrial localizations, and isoform-specific proteininteracting partners strongly support possible moonlighting functions for these proteins. In this chapter, we present a critical account of essential works on brain glutaminase 80 years after its discovery. We will highlight the impact of recent findings and thoughts in the context of the glutamate/glutamine brain homeostasis.
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Anterior cingulate Glutamate-Glutamine cycle metabolites are altered in euthymic bipolar I disorder. Eur Neuropsychopharmacol 2015; 25:2221-9. [PMID: 26476706 DOI: 10.1016/j.euroneuro.2015.09.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/27/2015] [Accepted: 09/28/2015] [Indexed: 12/12/2022]
Abstract
Bipolar disorder (BD) has been consistently associated with abnormalities in the Glutamate/GABA-Glutamine cycle. Magnetic resonance spectroscopy (MRS) studies have reported increased brain Glutamate (Glu) and Glx (Glu+Glutamine) in subjects with BD. However, data on separate measures of GABA and Glutamine (Gln) in BD are sparse due to overlapping resonant signals. The development of new sequence methods in the quantification of these metabolites has allowed a better understanding of the Glu/GABA-Gln cycle but data on this field of research remains sparse in BD. Eighty-eight subjects (50 euthymic BD and 38 HC) underwent 3T proton magnetic resonance spectroscopy (1H MRS) in the anterior cingulate cortex (ACC; 2×2×4.5cm(3)) using a two-dimensional JPRESS sequence. GABA, Glutamine (Gln) and Glutamate (Glu) were quantified with the ProFit program. Using image segmentation and known creatine (Cre) concentrations for white and grey matter, metabolite concentrations were calculated for the excited MRS voxel. GABA levels did not differ between groups. Gln level was higher in euthymic BD patients than in healthy controls. The Glu level and Glu/Gln ratio were lower in BD patients than in controls. The use of anticonvulsants was associated with Gln increase but did not affect Glu or Glu/Gln. Neither lithium nor antipsychotic use influenced metabolite levels. The ACC MRS findings indicate that the glutamatergic function in euthymic medicated BD patients is altered relative to controls. Whether this feature is a metabolic signature of euthymic BD subjects should be the focus of future studies.
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Indirect evidence of selective glial involvement in glutamate-based mechanisms of mood regulation in depression: meta-analysis of absolute prefrontal neuro-metabolic concentrations. Eur Neuropsychopharmacol 2015; 25:1109-17. [PMID: 26028038 DOI: 10.1016/j.euroneuro.2015.04.016] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 03/27/2015] [Accepted: 04/17/2015] [Indexed: 12/13/2022]
Abstract
Proton magnetic resonance spectroscopy ((1)H MRS) measures glutamatergic metabolites namely glutamate and glutamine located in neurons and astrocytes respectively. In this meta-analysis the contribution of glutamatergic neurotransmission to depressive symptoms was evaluated together with other putative prefrontal metabolites described in the pathogenesis of mood disorders, and in relation to treatment effects. A comprehensive literature search up to 2014 identified 17 reports which measured absolute concentrations of neurometabolites in the prefrontal cortex with (1)H MRS meeting criteria for inclusion in this meta-analysis. Excess of heterogeneity was investigated with meta-regressions. The analyses showed an exclusive reduction in absolute values of the composite measure of Glutamine and Glutamate (Glx) in the prefrontal cortex in depression, correlating in meta-regression analyses with treatment severity. Glutamate measurements in isolation did not differ vs. healthy controls or in relation to treatment and/or clinical improvement. Similarly there were no significant changes in other neurometabolites at baseline and following treatment. The analysis supports a role for glutamatergic dysfunction in the pathogeneses of mood dysregulation. The reduction in the absolute Glx values in the absence of changes in glutamate levels, suggests a possible modulatory role of astrocytes in the pathophysiology of depression.
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84
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Raju K, Doulias PT, Evans P, Krizman EN, Jackson JG, Horyn O, Daikhin Y, Nissim I, Yudkoff M, Nissim I, Sharp KA, Robinson MB, Ischiropoulos H. Regulation of brain glutamate metabolism by nitric oxide and S-nitrosylation. Sci Signal 2015; 8:ra68. [PMID: 26152695 DOI: 10.1126/scisignal.aaa4312] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nitric oxide (NO) is a signaling intermediate during glutamatergic neurotransmission in the central nervous system (CNS). NO signaling is in part accomplished through cysteine S-nitrosylation, a posttranslational modification by which NO regulates protein function and signaling. In our investigation of the protein targets and functional impact of S-nitrosylation in the CNS under physiological conditions, we identified 269 S-nitrosocysteine residues in 136 proteins in the wild-type mouse brain. The number of sites was significantly reduced in the brains of mice lacking endothelial nitric oxide synthase (eNOS(-/-)) or neuronal nitric oxide synthase (nNOS(-/-)). In particular, nNOS(-/-) animals showed decreased S-nitrosylation of proteins that participate in the glutamate/glutamine cycle, a metabolic process by which synaptic glutamate is recycled or oxidized to provide energy. (15)N-glutamine-based metabolomic profiling and enzymatic activity assays indicated that brain extracts from nNOS(-/-) mice converted less glutamate to glutamine and oxidized more glutamate than those from mice of the other genotypes. GLT1 [also known as EAAT2 (excitatory amino acid transporter 2)], a glutamate transporter in astrocytes, was S-nitrosylated at Cys(373) and Cys(561) in wild-type and eNOS(-/-) mice, but not in nNOS(-/-) mice. A form of rat GLT1 that could not be S-nitrosylated at the equivalent sites had increased glutamate uptake compared to wild-type GLT1 in cells exposed to an S-nitrosylating agent. Thus, NO modulates glutamatergic neurotransmission through the selective, nNOS-dependent S-nitrosylation of proteins that govern glutamate transport and metabolism.
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Affiliation(s)
- Karthik Raju
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paschalis-Thomas Doulias
- Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Perry Evans
- Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Elizabeth N Krizman
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Joshua G Jackson
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Oksana Horyn
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Yevgeny Daikhin
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Ilana Nissim
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Marc Yudkoff
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Itzhak Nissim
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kim A Sharp
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael B Robinson
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA. Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Harry Ischiropoulos
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA. Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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85
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Kompus K, Westerhausen R, Craven AR, Kreegipuu K, Põldver N, Passow S, Specht K, Hugdahl K, Näätänen R. Resting-state glutamatergic neurotransmission is related to the peak latency of the auditory mismatch negativity (MMN) for duration deviants: An1H-MRS-EEG study. Psychophysiology 2015; 52:1131-9. [DOI: 10.1111/psyp.12445] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 03/18/2015] [Indexed: 01/06/2023]
Affiliation(s)
- Kristiina Kompus
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- NORMENT Center of Excellence; University of Oslo; Oslo Norway
| | - René Westerhausen
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- Department of Psychology; University of Oslo; Oslo Norway
| | - Alex R. Craven
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- NORMENT Center of Excellence; University of Oslo; Oslo Norway
| | | | - Nele Põldver
- Institute of Psychology, University of Tartu; Tartu Estonia
- Doctoral School of Behavioural, Social and Health Sciences; University of Tartu; Tartu Estonia
| | - Susanne Passow
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- NORMENT Center of Excellence; University of Oslo; Oslo Norway
| | - Karsten Specht
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- Department of Clinical Engineering; Haukeland University Hospital; Bergen Norway
| | - Kenneth Hugdahl
- Department of Biological and Medical Psychology; University of Bergen; Bergen Norway
- NORMENT Center of Excellence; University of Oslo; Oslo Norway
- Division of Psychiatry; Haukeland University Hospital; Bergen Norway
- Department of Radiology; Haukeland University Hospital; Bergen Norway
| | - Risto Näätänen
- Institute of Psychology, University of Tartu; Tartu Estonia
- Institute of Behavioural Sciences, University of Helsinki; Helsinki Finland
- Center of Functionally Integrated Neurosciences (CFIN); University of Aarhus; Aarhus Denmark
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86
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Ortiz R, Niciu MJ, Lukkahati N, Saligan LN, Nugent AC, Luckenbaugh DA, Machado-Vieira R, Zarate CA. Shank3 as a potential biomarker of antidepressant response to ketamine and its neural correlates in bipolar depression. J Affect Disord 2015; 172:307-11. [PMID: 25451430 PMCID: PMC4400209 DOI: 10.1016/j.jad.2014.09.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 09/11/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND Shank3, a post-synaptic density protein involved in N-methyl-d-aspartate (NMDA) receptor tethering and dendritic spine rearrangement, is implicated in the pathophysiology of bipolar disorder. We hypothesized that elevated baseline plasma Shank3 levels might predict antidepressant response to the NMDA receptor antagonist ketamine. METHODS Twenty-nine subjects with bipolar depression received a double-blind, randomized, subanesthetic dose (.5 mg/kg) ketamine infusion. Of the patients for whom Shank3 levels were collected, 15 completed baseline 3-Tesla MRI and 17 completed post-ketamine [(18)F]-FDG PET. RESULTS Higher baseline Shank3 levels predicted antidepressant response at Days 1 (r=-.39, p=.047), 2 (r=-.45, p=.02), and 3 (r=-.42, p=.03) and were associated with larger average (r=.58, p=.02) and right amygdala volume (r=.65, p=.009). Greater baseline Shank3 also predicted increased glucose metabolism in the hippocampus (r=.51, p=.04) and amygdala (r=.58, p=.02). LIMITATIONS Limitations include the small sample size, inability to assess the source of peripheral Shank3, and the lack of a placebo group for baseline Shank3 levels and comparative structural/functional neuroimaging. CONCLUSIONS Shank3 is a potential biomarker of antidepressant response to ketamine that correlates with baseline amygdala volume and increased glucose metabolism in the amygdala and hippocampus.
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Affiliation(s)
- Robin Ortiz
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA
| | - Mark J. Niciu
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA
| | - Nada Lukkahati
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA,School of Nursing, University of Nevada at Las Vegas, Las Vegas, NV, USA
| | - Leorey N. Saligan
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA
| | - Allison C. Nugent
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA
| | - David A. Luckenbaugh
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA
| | - Rodrigo Machado-Vieira
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA
| | - Carlos A. Zarate
- National Institute of Mental Health, Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA,Corresponding author Carlos A. Zarate Jr. M.D., National Institutes of Health/National Institute of Mental Health, Experimental Therapeutics & Pathophysiology Branch, Building 10/Clinical Research Center (CRC), 10 Center Dr., Room 7-5342, Bethesda, MD 20892, Phone: (301)-451-0861, Fax: (301)-480-8792,
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87
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Nagasawa K, Kishida A, Kajiwara M, Kanamatsu T, Takatori K. A simple convenient synthesis of l-[4- 13C]glutamine. J Labelled Comp Radiopharm 2015; 58:42-5. [DOI: 10.1002/jlcr.3265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/06/2014] [Accepted: 12/26/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Kokoro Nagasawa
- Department of Synthetic Organic Chemistry; Meiji Pharmaceutical University; 2-522-1 Noshio Kiyose-shi Tokyo 204-8588 Japan
| | - Atsushi Kishida
- Department of Synthetic Organic Chemistry; Meiji Pharmaceutical University; 2-522-1 Noshio Kiyose-shi Tokyo 204-8588 Japan
| | - Masahiro Kajiwara
- Department of Synthetic Organic Chemistry; Meiji Pharmaceutical University; 2-522-1 Noshio Kiyose-shi Tokyo 204-8588 Japan
| | - Tomoyuki Kanamatsu
- Department of Environmental Engineering for Symbiosis, Faculty of Engineering; Soka University; 1-236 Tangi-Cho Hachioji Tokyo 192-8577 Japan
| | - Kazuhiko Takatori
- Department of Synthetic Organic Chemistry; Meiji Pharmaceutical University; 2-522-1 Noshio Kiyose-shi Tokyo 204-8588 Japan
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88
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Ballard ED, Lally N, Nugent AC, Furey ML, Luckenbaugh DA, Zarate CA. Neural correlates of suicidal ideation and its reduction in depression. Int J Neuropsychopharmacol 2015; 18:pyu069. [PMID: 25550331 PMCID: PMC4307932 DOI: 10.1093/ijnp/pyu069] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The neural correlates of suicidal ideation and its reduction after treatment are unknown. We hypothesized that increased regional cerebral glucose metabolism in the infralimbic cortex (Brodmann area 25), amygdala, and subgenual anterior cingulate cortex would be associated with suicidal ideation and its reduction after ketamine infusion. METHODS Medication-free patients (n=19) with treatment-resistant major depressive disorder underwent positron emission tomography imaging at baseline and 230 minutes after an open-label ketamine infusion (0.5 mg/kg for 40 minutes). RESULTS Baseline suicidal ideation and regional cerebral glucose metabolism in the infralimbic cortex were significantly correlated (r=.59, P=.007); but not overall mood scores (r=-.07, P=.79). Reductions in suicidal ideation after ketamine infusion were correlated with decreased regional cerebral glucose metabolism in the infralimbic cortex (r=.54, P=.02). Metabolism in other areas of interest was not significantly correlated with suicidal ideation or depression. CONCLUSION The infralimbic cortex may be implicated in suicidal ideation.
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Affiliation(s)
- Elizabeth D Ballard
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally).
| | - Níall Lally
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally)
| | - Allison C Nugent
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally)
| | - Maura L Furey
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally)
| | - David A Luckenbaugh
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally)
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Dr Ballard, Mr Lally, Dr Nugent, Dr Furey, Mr Luckenbaugh, and Dr Zarate); Institute of Cognitive Neuroscience, University College London, London, WC1N 3AR, UK (Mr Lally)
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89
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Ott P, Vilstrup H. Cerebral effects of ammonia in liver disease: current hypotheses. Metab Brain Dis 2014; 29:901-11. [PMID: 24488230 DOI: 10.1007/s11011-014-9494-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 01/21/2014] [Indexed: 12/15/2022]
Abstract
Hyperammonemia is necessary for development of the cerebral complications to liver disease including hepatic encephalopathy and cerebral edema but the mechanisms are unclear. Ammonia is taken up by the brain in proportion to its arterial concentration. The flux into the brain is most likely by both diffusion of NH3 and mediated transport of NH4 (+) . Astrocytic detoxification of ammonia involves formation of glutamine at concentrations high enough to produce cellular edema, but compensatory mechanisms reduce this effect. Glutamine can be taken up by astrocytic mitochondria and initiate the mitochondrial permeability transition but the clinical relevance is uncertain. Elevated astrocytic glutamine interferes with neurotransmission. Thus, animal studies show enhanced glutamatergic neurotransmission via the NMDA receptor which may be related to the acute cerebral complications to liver failure, while impairment of the NMDA activated glutamate-NO-cGMP pathway could relate to the behavioural changes seen in hepatic encephalopathy. Elevated glutamine also increases GABA-ergic tone, an effect which is aggravated by mitochondrial production of neurosteroids; this may relate to decreased neurotransmission and precipitation of encephalopathy by GABA targeting drugs. Hyperammonemia may compromise cerebral energy metabolism as elevated cerebral lactate is generally reported. Hypoxia is unlikely since cerebral oxygen:glucose utilisation and lactate:pyruvate ratio are both normal in clinical studies. Ammonia inhibits α-ketoglutaratedehydrogenase in isolated mitochondria, but the clinical relevance is dubious due to the observed normal cerebral oxygen:glucose utilization. Recent studies suggest that ammonia stimulates glycolysis in excess of TCA cycle activity, a hypothesis that may warrant further testing, in being in accordance with the limited clinical observations.
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Affiliation(s)
- Peter Ott
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, 8000C, Aarhus, Denmark,
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90
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Shulman RG, Hyder F, Rothman DL. Insights from neuroenergetics into the interpretation of functional neuroimaging: an alternative empirical model for studying the brain's support of behavior. J Cereb Blood Flow Metab 2014; 34:1721-35. [PMID: 25160670 PMCID: PMC4269754 DOI: 10.1038/jcbfm.2014.145] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 06/12/2014] [Accepted: 07/21/2014] [Indexed: 02/05/2023]
Abstract
Functional neuroimaging measures quantitative changes in neurophysiological parameters coupled to neuronal activity during observable behavior. These results have usually been interpreted by assuming that mental causation of behavior arises from the simultaneous actions of distinct psychological mechanisms or modules. However, reproducible localization of these modules in the brain using functional magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging has been elusive other than for sensory systems. In this paper, we show that neuroenergetic studies using PET, calibrated functional magnetic resonance imaging (fMRI), (13)C magnetic resonance spectroscopy, and electrical recordings do not support the standard approach, which identifies the location of mental modules from changes in brain activity. Of importance in reaching this conclusion is that changes in neuronal activities underlying the fMRI signal are many times smaller than the high ubiquitous, baseline neuronal activity, or energy in resting, awake humans. Furthermore, the incremental signal depends on the baseline activity contradicting theoretical assumptions about linearity and insertion of mental modules. To avoid these problems, while making use of these valuable results, we propose that neuroimaging should be used to identify observable brain activities that are necessary for a person's observable behavior rather than being used to seek hypothesized mental processes.
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Affiliation(s)
- Robert G Shulman
- Magnetic Resonance Research Center, Yale University, New Haven, Connecticut, USA
| | - Fahmeed Hyder
- Magnetic Resonance Research Center, Yale University, New Haven, Connecticut, USA
- Departments of Diagnostic Radiology, Yale University, New Haven, Connecticut, USA
- Biomedical Engineering, Yale University, New Haven, Connecticut, USA
- Quantitative Neuroscience with Magnetic Resonance Core Center, Yale University, New Haven, Connecticut, USA
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Yale University, New Haven, Connecticut, USA
- Departments of Diagnostic Radiology, Yale University, New Haven, Connecticut, USA
- Biomedical Engineering, Yale University, New Haven, Connecticut, USA
- Quantitative Neuroscience with Magnetic Resonance Core Center, Yale University, New Haven, Connecticut, USA
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91
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Characterization of cerebral glutamine uptake from blood in the mouse brain: implications for metabolic modeling of 13C NMR data. J Cereb Blood Flow Metab 2014; 34:1666-72. [PMID: 25074745 PMCID: PMC4269725 DOI: 10.1038/jcbfm.2014.129] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/10/2014] [Accepted: 06/30/2014] [Indexed: 01/20/2023]
Abstract
(13)C Nuclear Magnetic Resonance (NMR) studies of rodent and human brain using [1-(13)C]/[1,6-(13)C2]glucose as labeled substrate have consistently found a lower enrichment (∼25% to 30%) of glutamine-C4 compared with glutamate-C4 at isotopic steady state. The source of this isotope dilution has not been established experimentally but may potentially arise either from blood/brain exchange of glutamine or from metabolism of unlabeled substrates in astrocytes, where glutamine synthesis occurs. In this study, the contribution of the former was evaluated ex vivo using (1)H-[(13)C]-NMR spectroscopy together with intravenous infusion of [U-(13)C5]glutamine for 3, 15, 30, and 60 minutes in mice. (13)C labeling of brain glutamine was found to be saturated at plasma glutamine levels >1.0 mmol/L. Fitting a blood-astrocyte-neuron metabolic model to the (13)C enrichment time courses of glutamate and glutamine yielded the value of glutamine influx, VGln(in), 0.036±0.002 μmol/g per minute for plasma glutamine of 1.8 mmol/L. For physiologic plasma glutamine level (∼0.6 mmol/L), VGln(in) would be ∼0.010 μmol/g per minute, which corresponds to ∼6% of the glutamine synthesis rate and rises to ∼11% for saturating blood glutamine concentrations. Thus, glutamine influx from blood contributes at most ∼20% to the dilution of astroglial glutamine-C4 consistently seen in metabolic studies using [1-(13)C]glucose.
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92
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Anti-anhedonic effect of ketamine and its neural correlates in treatment-resistant bipolar depression. Transl Psychiatry 2014; 4:e469. [PMID: 25313512 PMCID: PMC4350513 DOI: 10.1038/tp.2014.105] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 07/14/2014] [Accepted: 08/13/2014] [Indexed: 02/06/2023] Open
Abstract
Anhedonia--which is defined as diminished pleasure from, or interest in, previously rewarding activities-is one of two cardinal symptoms of a major depressive episode. However, evidence suggests that standard treatments for depression do little to alleviate the symptoms of anhedonia and may cause reward blunting. Indeed, no therapeutics are currently approved for the treatment of anhedonia. Notably, over half of patients diagnosed with bipolar disorder experience significant levels of anhedonia during a depressive episode. Recent research into novel and rapid-acting therapeutics for depression, particularly the noncompetitive N-Methyl-D-aspartate receptor antagonist ketamine, has highlighted the role of the glutamatergic system in the treatment of depression; however, it is unknown whether ketamine specifically improves anhedonic symptoms. The present study used a randomized, placebo-controlled, double-blind crossover design to examine whether a single ketamine infusion could reduce anhedonia levels in 36 patients with treatment-resistant bipolar depression. The study also used positron emission tomography imaging in a subset of patients to explore the neurobiological mechanisms underpinning ketamine's anti-anhedonic effects. We found that ketamine rapidly reduced the levels of anhedonia. Furthermore, this reduction occurred independently from reductions in general depressive symptoms. Anti-anhedonic effects were specifically related to increased glucose metabolism in the dorsal anterior cingulate cortex and putamen. Our study emphasizes the importance of the glutamatergic system in treatment-refractory bipolar depression, particularly in the treatment of symptoms such as anhedonia.
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93
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Fayed N, Olivan-Blázquez B, Herrera-Mercadal P, Puebla-Guedea M, Pérez-Yus MC, Andrés E, López del Hoyo Y, Magallon R, Viguera L, Garcia-Campayo J. Changes in metabolites after treatment with memantine in fibromyalgia. A double-blind randomized controlled trial with magnetic resonance spectroscopy with a 6-month follow-up. CNS Neurosci Ther 2014; 20:999-1007. [PMID: 25230216 DOI: 10.1111/cns.12314] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/24/2014] [Accepted: 07/26/2014] [Indexed: 12/11/2022] Open
Abstract
AIM To evaluate the efficacy of memantine on metabolite levels in different areas of the brain and to determine whether changes in metabolite levels correlate with clinical variables in Fibromyalgia (FM) patients. METHODS Doubled-blind parallel randomized controlled trial. Twenty-five patients diagnosed with FM were enrolled in the study. Patients were administered questionnaires on pain, anxiety, depression, quality of life, and cognitive impairment, and single-voxel MRS of the brain was performed. All assessments were performed at baseline and after 6 months of treatment with memantine or placebo. RESULTS Patients treated with memantine exhibited a significant increase in the glutamate (P = 0.010), glutamate/creatine ratio (P = 0.013), combined glutamate + glutamine (P = 0.016) and total N-acetyl-aspartate (NAA+NAAG) (P = 0.034) in the posterior cingulate cortex compared with those on placebo. Furthermore, the memantine group exhibited increases in creatine (P = 0.013) and choline (Cho) (P = 0.025) in the right posterior insula and also a correlation between choline and the Fibromyalgia Impact Questionnaire (FIQ) in the posterior insula (P = 0.050) was observed. CONCLUSION Memantine treatment resulted in an increase in cerebral metabolism in FM patients, suggesting its utility for the treatment of the illness.
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Affiliation(s)
- Nicolás Fayed
- Magnetic Resonance Unit, Department of Radiology, Clinica Quiron, Zaragoza, Spain
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94
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Sertbaş M, Ülgen K, Çakır T. Systematic analysis of transcription-level effects of neurodegenerative diseases on human brain metabolism by a newly reconstructed brain-specific metabolic network. FEBS Open Bio 2014; 4:542-53. [PMID: 25061554 PMCID: PMC4104795 DOI: 10.1016/j.fob.2014.05.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 01/02/2023] Open
Abstract
Network-oriented analysis is essential to identify those parts of a cell affected by a given perturbation. The effect of neurodegenerative perturbations in the form of diseases of brain metabolism was investigated by using a newly reconstructed brain-specific metabolic network. The developed stoichiometric model correctly represents healthy brain metabolism, and includes 630 metabolic reactions in and between astrocytes and neurons, which are controlled by 570 genes. The integration of transcriptome data of six neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, schizophrenia) with the model was performed to identify reporter features specific and common for these diseases, which revealed metabolites and pathways around which the most significant changes occur. The identified metabolites are potential biomarkers for the pathology of the related diseases. Our model indicated perturbations in oxidative stress, energy metabolism including TCA cycle and lipid metabolism as well as several amino acid related pathways, in agreement with the role of these pathways in the studied diseases. The computational prediction of transcription factors that commonly regulate the reporter metabolites was achieved through binding-site analysis. Literature support for the identified transcription factors such as USF1, SP1 and those from FOX families are known from the literature to have regulatory roles in the identified reporter metabolic pathways as well as in the neurodegenerative diseases. In essence, the reconstructed brain model enables the elucidation of effects of a perturbation on brain metabolism and the illumination of possible machineries in which a specific metabolite or pathway acts as a regulatory spot for cellular reorganization.
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Key Words
- AD, Alzheimer’s disease
- ALS, amyotrophic lateral sclerosis
- Brain metabolic network
- Computational systems biology
- FBA, flux balance analysis
- GABA, gamma-aminobutyric acid
- HD, Huntington’s disease
- KIV, ketoisovalerate
- KLF, Krüppel-like factor
- KMV, alpha-keto-beta-methylvalerate
- MS, multiple sclerosis
- Neurodegenerative diseases
- Neurometabolism
- PCA, principal component analysis
- PD, Parkinson’s disease
- RMA, reporter metabolite analysis
- RPA, reporter pathway analysis
- Reporter metabolite
- SCHZ, schizophrenia
- TCA, tricarboxylic acid
- Transcriptome
- USF, upstream stimulatory factor
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Affiliation(s)
- Mustafa Sertbaş
- Department of Bioengineering, Gebze Institute of Technology, Gebze, Kocaeli, Turkey
- Department of Chemical Engineering, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
| | - Kutlu Ülgen
- Department of Chemical Engineering, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
| | - Tunahan Çakır
- Department of Bioengineering, Gebze Institute of Technology, Gebze, Kocaeli, Turkey
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95
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Kondo DG, Hellem TL, Shi XF, Sung YH, Prescot AP, Kim TS, Huber RS, Forrest LN, Renshaw PF. A review of MR spectroscopy studies of pediatric bipolar disorder. AJNR Am J Neuroradiol 2014; 35:S64-80. [PMID: 24557702 DOI: 10.3174/ajnr.a3844] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pediatric bipolar disorder is a severe mental illness whose pathophysiology is poorly understood and for which there is an urgent need for improved diagnosis and treatment. MR spectroscopy is a neuroimaging method capable of in vivo measurement of neurochemicals relevant to bipolar disorder neurobiology. MR spectroscopy studies of adult bipolar disorder provide consistent evidence for alterations in the glutamate system and mitochondrial function. In bipolar disorder, these 2 phenomena may be linked because 85% of glucose in the brain is consumed by glutamatergic neurotransmission and the conversion of glutamate to glutamine. The purpose of this article is to review the MR spectroscopic imaging literature in pediatric bipolar disorder, at-risk samples, and severe mood dysregulation, with a focus on the published findings that are relevant to glutamatergic and mitochondrial functioning. Potential directions for future MR spectroscopy studies of the glutamate system and mitochondrial dysfunction in pediatric bipolar disorder are discussed.
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Affiliation(s)
- D G Kondo
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, UtahDepartments of Psychiatry (D.G.K., X.F.S., Y.H.S., P.F.R.)
| | - T L Hellem
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, Utah
| | - X-F Shi
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, UtahDepartments of Psychiatry (D.G.K., X.F.S., Y.H.S., P.F.R.)
| | - Y H Sung
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, UtahDepartments of Psychiatry (D.G.K., X.F.S., Y.H.S., P.F.R.)
| | - A P Prescot
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, UtahRadiology (A.P.P.), University of Utah School of Medicine, Salt Lake City, Utah
| | - T S Kim
- and Department of Psychiatry (T.S.K.), Catholic University of Korea Graduate School of Medicine, Seoul, Republic of Korea
| | - R S Huber
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, Utah
| | - L N Forrest
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, Utah
| | - P F Renshaw
- From The Brain Institute (D.G.K., T.L.H., X.F.S., Y.H.S., A.P.P., R.S.H., L.N.F., P.F.R), University of Utah, Salt Lake City, UtahDepartments of Psychiatry (D.G.K., X.F.S., Y.H.S., P.F.R.)Veterans Integrated Service Network 19 Mental Illness Research (P.F.R.), Education and Clinical Center, VA Salt Lake City Health Care System, Salt Lake City, Utah
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96
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Liu X, Ser Z, Cluntun AA, Mentch SJ, Locasale JW. A strategy for sensitive, large scale quantitative metabolomics. J Vis Exp 2014. [PMID: 24894601 DOI: 10.3791/51358] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Metabolite profiling has been a valuable asset in the study of metabolism in health and disease. However, current platforms have different limiting factors, such as labor intensive sample preparations, low detection limits, slow scan speeds, intensive method optimization for each metabolite, and the inability to measure both positively and negatively charged ions in single experiments. Therefore, a novel metabolomics protocol could advance metabolomics studies. Amide-based hydrophilic chromatography enables polar metabolite analysis without any chemical derivatization. High resolution MS using the Q-Exactive (QE-MS) has improved ion optics, increased scan speeds (256 msec at resolution 70,000), and has the capability of carrying out positive/negative switching. Using a cold methanol extraction strategy, and coupling an amide column with QE-MS enables robust detection of 168 targeted polar metabolites and thousands of additional features simultaneously. Data processing is carried out with commercially available software in a highly efficient way, and unknown features extracted from the mass spectra can be queried in databases.
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Affiliation(s)
- Xiaojing Liu
- Division of Nutritional Sciences, Cornell University
| | - Zheng Ser
- Division of Nutritional Sciences, Cornell University
| | - Ahmad A Cluntun
- Division of Nutritional Sciences, Cornell University; Field of Biochemistry, and Molecular Cell Biology, Cornell University
| | - Samantha J Mentch
- Division of Nutritional Sciences, Cornell University; Field of Biochemistry, and Molecular Cell Biology, Cornell University
| | - Jason W Locasale
- Division of Nutritional Sciences, Cornell University; Field of Biochemistry, and Molecular Cell Biology, Cornell University;
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97
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Weltin A, Kieninger J, Enderle B, Gellner AK, Fritsch B, Urban GA. Polymer-based, flexible glutamate and lactate microsensors for in vivo applications. Biosens Bioelectron 2014; 61:192-9. [PMID: 24880657 DOI: 10.1016/j.bios.2014.05.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/02/2014] [Accepted: 05/06/2014] [Indexed: 12/28/2022]
Abstract
We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochemical in vivo monitoring. The sensor strip with a microelectrode array at the tip was designed for insertion into tissue, for fast and localized online monitoring of physiological parameters. The microsystem fabrication on a wafer-level is based on a polyimide substrate and includes the patterning of platinum microelectrodes as well as epoxy and dry-film-resist insulation in a cost-effective thin-film and laminate process. A stable, electrodeposited silver/silver chloride reference electrode on-chip and a perm-selective membrane as an efficient interference rejection scheme are integrated on a wafer-level. Amperometric, electrochemical, enzyme-based biosensors for the neurotransmitter L-glutamate and the energy metabolite L-lactate have been developed. Hydrogel membranes or direct cross-linking as stable concepts for the enzyme immobilization are shown. Sensor performance including high selectivity, tailoring of sensitivity and long-term stability is discussed. For glutamate, a high sensitivity of 2.16 nAmm(-2) µM(-1) was found. For lactate, a variation in sensitivity between 2.6 and 32 nAmm(-2)mM(-1) was achieved by different membrane compositions. The in vivo application in an animal model is demonstrated by glutamate measurements in the brain of rats. Local glutamate alterations in the micromolar range and in nanoliter-range volumes can be detected and quantified with high reproducibility and temporal resolution. A novel, versatile platform for the integration of various electrochemical sensors on a small, flexible sensor strip for a variety of in vivo applications is presented.
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Affiliation(s)
- Andreas Weltin
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany.
| | - Jochen Kieninger
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany
| | - Barbara Enderle
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany
| | | | - Brita Fritsch
- Department of Neurology, University of Freiburg, Germany
| | - Gerald A Urban
- Laboratory for Sensors, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany
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98
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de Graaf RA, Chowdhury GMI, Behar KL. Quantification of high-resolution ¹H-[¹³C] NMR spectra from rat brain extracts. Anal Chem 2014; 86:5032-8. [PMID: 24773047 PMCID: PMC4033633 DOI: 10.1021/ac5006926] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NMR spectroscopy in combination with (13)C-labeled substrate infusion is a unique technique to obtain information about dynamic metabolic fluxes noninvasively in vivo. In many cases, the in vivo information content obtained during dynamic (13)C studies in rodents can be enhanced by high-resolution (1)H-[(13)C] NMR spectroscopy on brain extracts. Previously, it has been shown that (1)H NMR spectra from rat brain extracts can be accurately quantified with a spectral fitting routine utilizing simulated basis sets using complete prior knowledge of chemical shifts and scalar couplings. The introduction of (13)C label into the various metabolites presents complications that demand modifications of the spectral fitting routine. As different multiplets within a given molecule accumulate various amounts of (13)C label, the fixed amplitude relationship between multiplets typical for (1)H NMR spectra must be abandoned. In addition, (13)C isotope effects lead to spectral multiplet patterns that become dependent on the amount of (13)C label accumulation, thereby preventing the use of a common basis set. Here a modified spectral fitting routine is presented that accommodates variable (13)C label accumulation and (13)C isotope effects. Spectral fitting results are quantitatively compared to manual integration on column-separated samples in which spectral overlap is minimized.
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Affiliation(s)
- Robin A de Graaf
- Magnetic Resonance Research Center, †Department of Diagnostic Radiology and ‡Department of Psychiatry, Yale University School of Medicine , New Haven, Connecticut 06510, United States
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99
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Herculano-Houzel S. The glia/neuron ratio: how it varies uniformly across brain structures and species and what that means for brain physiology and evolution. Glia 2014; 62:1377-91. [PMID: 24807023 DOI: 10.1002/glia.22683] [Citation(s) in RCA: 370] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 10/03/2013] [Accepted: 04/18/2014] [Indexed: 12/11/2022]
Abstract
It is a widespread notion that the proportion of glial to neuronal cells in the brain increases with brain size, to the point that glial cells represent "about 90% of all cells in the human brain." This notion, however, is wrong on both counts: neither does the glia/neuron ratio increase uniformly with brain size, nor do glial cells represent the majority of cells in the human brain. This review examines the origin of interest in the glia/neuron ratio; the original evidence that led to the notion that it increases with brain size; the extent to which this concept can be applied to white matter and whole brains and the recent supporting evidence that the glia/neuron ratio does not increase with brain size, but rather, and in surprisingly uniform fashion, with decreasing neuronal density due to increasing average neuronal cell size, across brain structures and species. Variations in the glia/neuron ratio are proposed to be related not to the supposed larger metabolic cost of larger neurons (given that this cost is not found to vary with neuronal density), but simply to the large variation in neuronal sizes across brain structures and species in the face of less overall variation in glial cell sizes, with interesting implications for brain physiology. The emerging evidence that the glia/neuron ratio varies uniformly across the different brain structures of mammalian species that diverged as early as 90 million years ago in evolution highlights how fundamental for brain function must be the interaction between glial cells and neurons.
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Affiliation(s)
- Suzana Herculano-Houzel
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Instituto Nacional de Neurociência Translacional, São Paulo, SP, Brazil
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100
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Direct evidence for activity-dependent glucose phosphorylation in neurons with implications for the astrocyte-to-neuron lactate shuttle. Proc Natl Acad Sci U S A 2014; 111:5385-90. [PMID: 24706914 DOI: 10.1073/pnas.1403576111] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Previous (13)C magnetic resonance spectroscopy experiments have shown that over a wide range of neuronal activity, approximately one molecule of glucose is oxidized for every molecule of glutamate released by neurons and recycled through astrocytic glutamine. The measured kinetics were shown to agree with the stoichiometry of a hypothetical astrocyte-to-neuron lactate shuttle model, which predicted negligible functional neuronal uptake of glucose. To test this model, we measured the uptake and phosphorylation of glucose in nerve terminals isolated from rats infused with the glucose analog, 2-fluoro-2-deoxy-D-glucose (FDG) in vivo. The concentrations of phosphorylated FDG (FDG6P), normalized with respect to known neuronal metabolites, were compared in nerve terminals, homogenate, and cortex of anesthetized rats with and without bicuculline-induced seizures. The increase in FDG6P in nerve terminals agreed well with the increase in cortical neuronal glucose oxidation measured previously under the same conditions in vivo, indicating that direct uptake and oxidation of glucose in nerve terminals is substantial under resting and activated conditions. These results suggest that neuronal glucose-derived pyruvate is the major oxidative fuel for activated neurons, not lactate-derived from astrocytes, contradicting predictions of the original astrocyte-to-neuron lactate shuttle model under the range of study conditions.
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