1
|
Craven AR, Dwyer G, Ersland L, Kazimierczak K, Noeske R, Sandøy LB, Johnsen E, Hugdahl K. GABA, glutamatergic dynamics and BOLD contrast assessed concurrently using functional MRS during a cognitive task. NMR IN BIOMEDICINE 2024; 37:e5065. [PMID: 37897259 DOI: 10.1002/nbm.5065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/30/2023]
Abstract
A recurring issue in functional neuroimaging is how to link task-driven haemodynamic blood oxygen level dependent functional MRI (BOLD-fMRI) responses to underlying neurochemistry at the synaptic level. Glutamate and γ-aminobutyric acid (GABA), the major excitatory and inhibitory neurotransmitters respectively, are typically measured with MRS sequences separately from fMRI, in the absence of a task. The present study aims to resolve this disconnect, developing acquisition and processing techniques to simultaneously assess GABA, glutamate and glutamine (Glx) and BOLD in relation to a cognitive task, at 3 T. Healthy subjects (N = 81) performed a cognitive task (Eriksen flanker), which was presented visually in a task-OFF, task-ON block design, with individual event onset timing jittered with respect to the MRS readout. fMRS data were acquired from the medial anterior cingulate cortex during task performance, using an adapted MEGA-PRESS implementation incorporating unsuppressed water-reference signals at a regular interval. These allowed for continuous assessment of BOLD activation, through T2 *-related changes in water linewidth. BOLD-fMRI data were additionally acquired. A novel linear model was used to extract modelled metabolite spectra associated with discrete functional stimuli, building on well established processing and quantification tools. Behavioural outcomes from the flanker task, and activation patterns from the BOLD-fMRI sequence, were as expected from the literature. BOLD response assessed through fMRS showed a significant correlation with fMRI, specific to the fMRS-targeted region of interest; fMRS-assessed BOLD additionally correlated with lengthening of response time in the incongruent flanker condition. While no significant task-related changes were observed for GABA+, a significant increase in measured Glx levels (~8.8%) was found between task-OFF and task-ON periods. These findings verify the efficacy of our protocol and analysis pipelines for the simultaneous assessment of metabolite dynamics and BOLD. As well as establishing a robust basis for further work using these techniques, we also identify a number of clear directions for further refinement in future studies.
Collapse
Affiliation(s)
- Alexander R Craven
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
- NORMENT Center of Excellence, Haukeland University Hospital, Bergen, Norway
| | - Gerard Dwyer
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- NORMENT Center of Excellence, Haukeland University Hospital, Bergen, Norway
| | - Lars Ersland
- Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
- NORMENT Center of Excellence, Haukeland University Hospital, Bergen, Norway
| | | | | | - Lydia Brunvoll Sandøy
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Erik Johnsen
- NORMENT Center of Excellence, Haukeland University Hospital, Bergen, Norway
- Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Kenneth Hugdahl
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
- Department of Radiology, Haukeland University Hospital, Bergen, Norway
| |
Collapse
|
2
|
Association of the delayed changes in glutamate levels and functional connectivity with the immediate network effects of S-ketamine. Transl Psychiatry 2023; 13:60. [PMID: 36797238 PMCID: PMC9935558 DOI: 10.1038/s41398-023-02346-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/18/2023] Open
Abstract
Ketamine shows rapid antidepressant effects peaking 24 h after administration. The antidepressant effects may occur through changes in glutamatergic metabolite levels and resting-state functional connectivity (rsFC) within the default mode network (DMN). A multistage drug effect of ketamine has been suggested, inducing acute effects on dysfunctional network configuration and delayed effects on homeostatic synaptic plasticity. Whether the DMN-centered delayed antidepressant-related changes are associated with the immediate changes remains unknown. Thirty-five healthy male participants (25.1 ± 4.2 years) underwent 7 T magnetic resonance spectroscopy (MRS) and resting-state functional magnetic resonance imaging (rsfMRI) before, during, and 24 h after a single S-ketamine or placebo infusion. Changes in glutamatergic measures and rsFC in the DMN node pregenual anterior cingulate cortex (pgACC) were examined. A delayed rsFC decrease of the pgACC to inferior parietal lobe (family-wise error corrected p (pFWEc) = 0.018) and dorsolateral prefrontal cortex (PFC; pFWEc = 0.002) was detected that was preceded by an immediate rsFC increase of the pgACC to medial PFC (pFWEc < 0.001) and dorsomedial PFC (pFWEc = 0.005). Additionally, the immediate rsFC reconfigurations correlated with the delayed pgACC glutamate (Glu) level increase (p = 0.024) after 24 h at trend level (p = 0.067). Baseline measures of rsFC and MRS were furthermore associated with the magnitude of the respective delayed changes (p's < 0.05). In contrast, the delayed changes were not associated with acute psychotomimetic side effects or plasma concentrations of ketamine and its metabolites. This multimodal study suggests an association between immediate S-ketamine-induced network effects and delayed brain changes at a time point relevant in its clinical context.
Collapse
|
3
|
Moxon-Emre I, Daskalakis ZJ, Blumberger DM, Croarkin PE, Lyon RE, Forde NJ, Tani H, Truong P, Lai MC, Desarkar P, Sailasuta N, Szatmari P, Ameis SH. Modulation of Dorsolateral Prefrontal Cortex Glutamate/Glutamine Levels Following Repetitive Transcranial Magnetic Stimulation in Young Adults With Autism. Front Neurosci 2021; 15:711542. [PMID: 34690671 PMCID: PMC8527173 DOI: 10.3389/fnins.2021.711542] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 09/13/2021] [Indexed: 12/29/2022] Open
Abstract
Altered excitatory and inhibitory neurotransmission has been implicated in autism spectrum disorder (ASD). Interventions using repetitive transcranial magnetic stimulation (rTMS) to enhance or inhibit cortical excitability are under study for various targets, though the mechanistic effects of rTMS have yet to be examined in ASD. Here, we examined whether an excitatory rTMS treatment course modulates glutamatergic (Glx) or γ-aminobutyric acid (GABA) metabolite levels in emerging adults with ASD. Twenty-eight participants with ASD and executive function impairment [23.3 ± 4.69 years; seven-female] underwent two magnetic resonance spectroscopy (MRS) scans of the left dorsolateral prefrontal cortex (DLPFC). MRS scans were acquired before and after participants with ASD were randomized to receive a 20-session course of active or sham rTMS to the DLPFC. Baseline MRS data was available for 19 typically developing controls [23.8 ± 4.47 years; six-female]. Metabolite levels for Glx and GABA+ were compared between ASD and control groups, at baseline, and metabolite level change, pre-to-post-rTMS treatment, was compared in ASD participants that underwent active vs. sham rTMS. Absolute change in Glx was greater in the active vs. sham-rTMS group [F(1,19) = 6.54, p = 0.02], though the absolute change in GABA+ did not differ between groups. We also examined how baseline metabolite levels related to pre/post-rTMS metabolite level change, in the active vs. sham groups. rTMS group moderated the relation between baseline Glx and pre-to-post-rTMS Glx change, such that baseline Glx predicted Glx change in the active-rTMS group only [b = 1.52, SE = 0.32, t(18) = 4.74, p < 0.001]; Glx levels increased when baseline levels were lower, and decreased when baseline levels were higher. Our results indicate that an interventional course of excitatory rTMS to the DLPFC may modulate local Glx levels in emerging adults with ASD, and align with prior reports of glutamatergic alterations following rTMS. Interventional studies that track glutamatergic markers may provide mechanistic insights into the therapeutic potential of rTMS in ASD. Clinical Trial Registration:Clinicaltrials.gov (ID: NCT02311751), https://clinicaltrials.gov/ct2/show/NCT02311751?term=ameis&rank=1; NCT02311751.
Collapse
Affiliation(s)
- Iska Moxon-Emre
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Zafiris J Daskalakis
- Temerty Centre for Therapeutic Brain Intervention, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Daniel M Blumberger
- Temerty Centre for Therapeutic Brain Intervention, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Paul E Croarkin
- Division of Child and Adolescent Psychiatry, Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, United States
| | - Rachael E Lyon
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Natalie J Forde
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, Netherlands
| | - Hideaki Tani
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Peter Truong
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Meng-Chuan Lai
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Department of Psychiatry, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Psychology, University of Toronto, Toronto, ON, Canada
| | - Pushpal Desarkar
- Temerty Centre for Therapeutic Brain Intervention, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Napapon Sailasuta
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Peter Szatmari
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Department of Psychiatry, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Stephanie H Ameis
- Cundill Centre for Child and Youth Depression, The Margaret and Wallace McCain Centre for Child, Youth & Family Mental Health, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Department of Psychiatry, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| |
Collapse
|
4
|
Zöllner HJ, Oeltzschner G, Schnitzler A, Wittsack HJ. In silico GABA+ MEGA-PRESS: Effects of signal-to-noise ratio and linewidth on modeling the 3 ppm GABA+ resonance. NMR IN BIOMEDICINE 2021; 34:e4410. [PMID: 32989890 PMCID: PMC8935357 DOI: 10.1002/nbm.4410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 08/11/2020] [Accepted: 08/28/2020] [Indexed: 06/02/2023]
Abstract
To investigate the GABA+ modeling accuracy of MEGA-PRESS GABA+-edited MRS data with various spectral quality scenarios, the influence of varying signal-to-noise ratio (SNR) and linewidth on the model estimates was quantified. MEGA-PRESS data from 46 volunteers were averaged to generate a template MEGA-PRESS spectrum, which was modeled and quantified to generate a GABA+ level ground truth. This spectrum was then manipulated by adding 427 combinations of varying artificial noise levels and line broadening, mimicking variations in GABA+ SNR and B0 homogeneity. GABA+ modeling and quantification was performed with 100 simulated spectra per condition using automated routines in both Gannet 3.0 and Tarquin. The GABA+ estimation error was calculated as the relative deviation to the quantified GABA+ ground truth levels to assess the accuracy of GABA+ modeling. Finally, the accordance between the simulations and different in vivo scenarios was assessed. The GABA+ estimation error was smaller than 5% for all GABA+ SNR values with creatine linewidths lower than 9.7 Hz in Gannet 3.0 or unequal 10.6 Hz in Tarquin. The standard deviation of the GABA+ amplitude over 100 spectra per condition varied between 3.1 and 17% (Gannet 3.0) and between 1 and 11% (Tarquin) over the in vivo relevant GABA+ SNR range between 2.6 and 3.5. GABA+ edited studies might be realized for voxels with low GABA+ SNR at the cost of higher group-level variance. The accuracy of GABA+ modeling had no relation to commonly used quality metrics. The Tarquin algorithm was found to be more robust against linewidth changes than the fitting algorithm in Gannet.
Collapse
Affiliation(s)
- Helge Jörn Zöllner
- institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
- Department of Diagnostic and Interventional Radiology, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Alfons Schnitzler
- institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
| | - Hans-Jörg Wittsack
- Department of Diagnostic and Interventional Radiology, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
| |
Collapse
|
5
|
van Vugt FT, Near J, Hennessy T, Doyon J, Ostry DJ. Early stages of sensorimotor map acquisition: neurochemical signature in primary motor cortex and its relation to functional connectivity. J Neurophysiol 2020; 124:1615-1624. [PMID: 32997558 DOI: 10.1152/jn.00285.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The earliest stages of sensorimotor learning involve learning the correspondence between movements and sensory results-a sensorimotor map. The present exploratory study investigated the neurochemical underpinnings of map acquisition by monitoring 25 participants as they acquired a new association between movements and sounds. Functional magnetic resonance spectroscopy was used to measure neurochemical concentrations in the left primary motor cortex during learning. Resting-state functional magnetic resonance imaging data were also collected before and after training to assess learning-related changes in functional connectivity. There were monotonic increases in γ-aminobutyric acid (GABA) and decreases in glucose during training, which extended into the subsequent rest period and, importantly, in the case of GABA correlated with the amount of learning: participants who showed greater behavioral learning showed greater GABA increase. The GABA change was furthermore correlated with changes in functional connectivity between the primary motor cortex and a cluster of voxels in the right intraparietal sulcus: greater increases in GABA were associated with greater strengthening of connectivity. Transiently, there were increases in lactate and reductions in aspartate, which returned to baseline at the end of training, but only lactate showed a statistical trend to correlate with the amount of learning. In summary, during the earliest stages of sensorimotor learning, GABA levels are linked on a subject-level basis to both behavioral learning and a strengthening of functional connections that persists beyond the training period. The findings are consistent with the idea that GABA-mediated inhibition is linked to maintenance of newly learned information.NEW & NOTEWORTHY Learning the mapping between movements and their sensory effects is a necessary step in the early stages of sensorimotor learning. There is evidence showing which brain areas are involved in early motor learning, but their role remains uncertain. Here, we show that GABA, a neurotransmitter linked to inhibitory processing, rises during and after learning and is involved in ongoing changes in resting-state networks.
Collapse
Affiliation(s)
- F T van Vugt
- Department of Psychology, McGill University, Montreal, Quebec, Canada.,Haskins Laboratories, New Haven, Connecticut.,Department of Psychology, University of Montreal, Montreal, Quebec, Canada
| | - J Near
- Douglas Mental Health University Institute, Montreal, Quebec, Canada.,Department of Biomechanical Engineering, McGill University, Montreal, Quebec, Canada
| | - T Hennessy
- Douglas Mental Health University Institute, Montreal, Quebec, Canada.,Department of Biomechanical Engineering, McGill University, Montreal, Quebec, Canada
| | - J Doyon
- Department of Psychology, University of Montreal, Montreal, Quebec, Canada.,Unité de Neuroimagerie Fonctionnelle, Centre de recherche, Institut universitaire de gériatrie de Montréal, Montreal, Quebec, Canada.,Department Of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - D J Ostry
- Department of Psychology, McGill University, Montreal, Quebec, Canada.,Haskins Laboratories, New Haven, Connecticut
| |
Collapse
|
6
|
Genetic variant in SLC1A2 is associated with elevated anterior cingulate cortex glutamate and lifetime history of rapid cycling. Transl Psychiatry 2019; 9:149. [PMID: 31123248 PMCID: PMC6533282 DOI: 10.1038/s41398-019-0483-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/07/2019] [Accepted: 04/10/2019] [Indexed: 12/13/2022] Open
Abstract
Glutamatergic dysregulation is implicated in the neurobiology of mood disorders. This study investigated the relationship between the anterior cingulate cortex (AC) glutamate, as measured by proton magnetic resonance spectroscopy (1H-MRS), and single-nucleotide polymorphisms (SNPs) from four genes (GLUL, SLC1A3, SLC1A2, and SLC1A7) that regulate the extracellular glutamate in 26 depressed patients with major depressive disorder (MDD; n = 15) and bipolar disorder (BD; n = 11). Two SNPs (rs3812778 and rs3829280), in perfect linkage disequilibrium, in the 3' untranslated region of the EAAT2 gene SLC1A2, were associated with AC glutamate, with minor allele carriers having significantly higher glutamate levels (p < 0.001) in comparison with common allele homozygotes. In silico analysis revealed an association of minor allele carriers of rs3812778/rs382920 with an upregulation of the astrocytic marker CD44 localized downstream of SLC1A2 on chromosome 11. Finally, we tested the disease relevance of these SNPs in a large group of depressed patients [MDD (n = 458); BD (n = 1473)] and found that minor allele carriers had a significantly higher risk for rapid cycling (p = 0.006). Further work is encouraged to delineate the functional impact of excitatory amino acid transporter genetic variation on CD44 associated physiology and glutamatergic neurotransmission, specifically glutamate-glutamine cycling, and its contribution to subphenotypes of mood disorders.
Collapse
|
7
|
Dhamala E, Abdelkefi I, Nguyen M, Hennessy TJ, Nadeau H, Near J. Validation of in vivo MRS measures of metabolite concentrations in the human brain. NMR IN BIOMEDICINE 2019; 32:e4058. [PMID: 30663818 DOI: 10.1002/nbm.4058] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 11/15/2018] [Accepted: 11/17/2018] [Indexed: 05/05/2023]
Abstract
PURPOSE In vivo magnetic resonance spectroscopy (MRS) is the only technique capable of non-invasively assessing metabolite concentrations in the brain. The lack of alternative methods makes validation of MRS measures challenging. The aim of this study is to assess the validity of MRS measures of human brain metabolite concentrations by comparing multiple MRS measures acquired using different MRS acquisition sequences. METHODS Single-voxel SPECIAL and MEGA-PRESS MR spectra were acquired from both the dorsolateral prefrontal cortex and primary motor cortices in 15 healthy subjects. The SPECIAL spectrum, as well as both the edit-off and difference spectra of MEGA-PRESS were each analyzed in LCModel to obtain estimates of the absolute concentrations of total choline (TCh; glycerophosphocholine + phosphocholine), total creatine (TCr; creatine + phosphocreatine), N-acetylaspartate (NAA), N-acetylaspartylglutamate (NAAG), NAA + NAAG, glutamate (Glu), glutamine (Gln), Glu + Gln, scyllo-inositol (Scyllo), myo-inositol (Ins), glutathione (GSH), γ-aminobutyric acid (GABA), lactate (Lac) and aspartate (Asp). Then, having obtained up to three independent measures of each metabolite per brain region per subject, correlations between the different measures were assessed. RESULTS The degree of correlation between measures varied greatly across both the metabolites and sequences tested. As expected, metabolites with the most prominent spectral peaks (TCh, TCr, NAA + NAAG, Ins and Glu) had the most well-correlated measures between methods, while metabolites with less prominent spectral peaks (Lac, Gln, GABA, Asp, and NAAG) tended to have poorly-correlated measures between methods. Some metabolites with relatively less prominent spectral peaks (GSH, Scyllo) had fairly well-correlated measures between some methods. Combining metabolites improved the agreement between methods for measures of NAA + NAAG, but not for Glu + Gln. CONCLUSIONS Given that the ground truth for in vivo MRS measures is never known, the method proposed here provides a promising means to assess the validity of in vivo MRS measures, which has not yet been explored widely.
Collapse
Affiliation(s)
- Elvisha Dhamala
- Centre d'Imagerie Cérébrale, Douglas Mental Health University Institute, Montreal, Canada
| | | | - Mavesa Nguyen
- Department of Physics, Dawson College, Montreal, Canada
- Department of Mechanical Engineering, McGill University, Montreal, Canada
| | - T Jay Hennessy
- Centre d'Imagerie Cérébrale, Douglas Mental Health University Institute, Montreal, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Canada
| | - Hélène Nadeau
- Department of Physics, Dawson College, Montreal, Canada
| | - Jamie Near
- Centre d'Imagerie Cérébrale, Douglas Mental Health University Institute, Montreal, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Canada
| |
Collapse
|
8
|
O'Gorman Tuura R, Warnock G, Ametamey S, Treyer V, Noeske R, Buck A, Sommerauer M. Imaging glutamate redistribution after acute N-acetylcysteine administration: A simultaneous PET/MR study. Neuroimage 2018; 184:826-833. [PMID: 30296554 DOI: 10.1016/j.neuroimage.2018.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/31/2018] [Accepted: 10/04/2018] [Indexed: 12/25/2022] Open
Abstract
Glutamate is the most abundant excitatory neurotransmitter in the human brain, but in vivo imaging of acute fluctuations in glutamatergic levels has not been well established. The purpose of this study was to examine acute changes in glutamate after stimulation with N-acetylcysteine (NAC) using a simultaneous positron emission tomography/magnetic resonance spectroscopy (PET/MRS) approach. Ten healthy adult males were examined in two scanning sessions, and 5g NAC was administered 1 h prior to one of the scan sessions. Simultaneous PET/MR data were acquired using an integrated 3T PET/MR scanner. Glutamate (Glu), glutamine (Gln), and glutamate + glutamine (Glx) levels were assessed from MRS data collected from the basal ganglia with PRESS and from the left prefrontal cortex with PRESS and MEGAPRESS, and mGluR5 binding (BPND) was assessed from PET data collected with [18F]PSS232. NAC administration was associated with a significant reduction in Glx and Gln in the basal ganglia spectra, and in Glx in the frontal MEGAPRESS spectra (p < 0.05); no differences in [18F]PSS232 BPND were observed with NAC, although a correlation between pre-/post-treatment Glx and baseline BPnd was found. The MRS-visible Glx signal is sensitive to acute fluctuations in glutamate. The change in Glx was mostly driven by a change in Gln, lending weight to the notion that Gln can provide a proxy marker for neurotransmitter/synaptic glutamate. [18F]PSS232 binding is not sensitive to acute glutamate shifts independently, but was associated with the extent of glutamate liberation upon NAC stimulation.
Collapse
Affiliation(s)
- Ruth O'Gorman Tuura
- Center for MR Research, University Children's Hospital, Steinwiesstrasse 75, CH-8032, Zürich, Switzerland.
| | - Geoff Warnock
- Department of Nuclear Medicine, University Hospital Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland
| | - Simon Ametamey
- Center for Radiopharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Vladimir-Prelog-Weg 4 4, CH-8093, Zürich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland
| | | | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland
| | - Michael Sommerauer
- Department of Nuclear Medicine, University Hospital Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland; Department of Neurology, University Hospital Cologne, Kerpener Str. 62, 50937, Cologne, Germany
| |
Collapse
|
9
|
O'Gorman Tuura RL, Baumann CR, Baumann-Vogel H. Neurotransmitter activity is linked to outcome following subthalamic deep brain stimulation in Parkinson's disease. Parkinsonism Relat Disord 2018; 50:54-60. [PMID: 29472099 DOI: 10.1016/j.parkreldis.2018.02.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 01/24/2018] [Accepted: 02/07/2018] [Indexed: 11/16/2022]
Abstract
INTRODUCTION While the mechanisms underlying the therapeutic effects of deep brain stimulation (DBS) in Parkinson's Disease (PD) are not yet fully understood, DBS appears to exert a wide range of neurochemical effects on the network level, thought to arise from activation of inhibitory and excitatory pathways. The activity within the primary inhibitory (GABAergic) and excitatory (glutamatergic) neurotransmitter systems may therefore play an important role in the therapeutic efficacy of DBS in PD. The purpose of this study was to investigate abnormalities in GABA-ergic and glutamatergic neurotransmission in PD, and to examine the link between neurotransmitter levels and outcome following DBS. METHODS Magnetic resonance spectra were acquired from the pons and basal ganglia in sixteen patients with PD and sixteen matched control participants. GABA and glutamate levels were quantified with LCModel, an automated spectral fitting package. Fourteen patients subsequently underwent DBS, and PD symptoms were evaluated with the MDS-UPDRS at baseline and six months after surgery. The efficacy of DBS treatment was evaluated from the percentage improvement in MDS-UPDRS scores. RESULTS Basal ganglia GABA levels were significantly higher in PD patients relative to control participants (p < 0.01), while pontine glutamate + glutamine (Glx) levels were significantly lower in patients with PD (p < 0.05). While GABA levels were not significantly related to outcome post-surgery, basal ganglia glutamate levels emerged as a significant predictor of outcome, suggesting a possible role for glutamatergic neurotransmission in the therapeutic mechanism of DBS. CONCLUSION GABAergic and glutamatergic neurotransmission is altered in PD, and glutamatergic activity in particular may influence outcome post-surgery.
Collapse
Affiliation(s)
- Ruth L O'Gorman Tuura
- Center for MR Research, University Children's Hospital Zurich, Steinwiesstrasse 75, Zurich, 8032, Switzerland.
| | - Christian R Baumann
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, Zurich, 8091, Switzerland
| | - Heide Baumann-Vogel
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, Zurich, 8091, Switzerland
| |
Collapse
|
10
|
Zhang Y, An L, Shen J. Fast computation of full density matrix of multispin systems for spatially localized in vivo magnetic resonance spectroscopy. Med Phys 2017; 44:4169-4178. [PMID: 28548302 DOI: 10.1002/mp.12375] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/16/2017] [Accepted: 05/16/2017] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Numerical simulations of three-dimensionally localized MRS spectra have been very time consuming for multispin systems because the current state-of-the-art method requires computation of a large ensemble of spins pixel-by-pixel in three dimensional space. This paper describes a highly accelerated technique for computing spatially localized MRS spectra using the full solution to the Liouville-von Neumann equation. METHODS The time evolution of spatially localized multispin density matrix as the full solution to the Liouville-von Neumann equation was analyzed. A new technique based on one dimensional spatial projection of the full density matrix was proposed. This method was implemented using a computer program written in Java language. RESULTS The MRS spectra calculated using the new method were found to be identical to conventional three-dimensional simulation for the same digitization of the voxel while the new method reduced computation time by orders of magnitude and led to not only improved speed but also accuracy. Applications of the new method to phantom studies of multispin systems and quantification of in vivo MRS spectra of brain were demonstrated. CONCLUSION The dramatically enhanced computational efficiency makes accurate simulation of localized MRS spectra highly accessible for calculating basis sets for spectral quantification and for optimizing pulse sequences.
Collapse
Affiliation(s)
- Yan Zhang
- MR Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Li An
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jun Shen
- MR Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA.,Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Li M, Demenescu LR, Colic L, Metzger CD, Heinze HJ, Steiner J, Speck O, Fejtova A, Salvadore G, Walter M. Temporal Dynamics of Antidepressant Ketamine Effects on Glutamine Cycling Follow Regional Fingerprints of AMPA and NMDA Receptor Densities. Neuropsychopharmacology 2017; 42:1201-1209. [PMID: 27604568 PMCID: PMC5437874 DOI: 10.1038/npp.2016.184] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 08/26/2016] [Accepted: 08/29/2016] [Indexed: 11/09/2022]
Abstract
The anterior cingulate cortex (ACC) has shown decreased glutamate levels in patients with major depressive disorder. Subanesthetic doses of ketamine were repeatedly shown to improve depressive symptoms within 24 h after infusion and this antidepressant effect was attributed to increased α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) throughput. To elucidate ketamine's mechanism of action, we tested whether the clinical time course of the improvement is mirrored by the change of glutamine/glutamate ratio and if such effects show a regional and temporal specificity in two distinct subdivisions of ACC with different AMPA/N-methyl-D-aspartate receptor profiles. In a double-blind, placebo-controlled intravenous infusion study of ketamine, we measured glutamate and glutamine in the pregenual ACC (pgACC) and the anterior midcingulate cortex at 1 and 24 h post infusion with magnetic resonance spectroscopy at 7 T. A significant interaction of time, region, and treatment was found for the glutamine/glutamate ratios (placebo, n=14; ketamine, n=12). Post-hoc analyses revealed that the glutamine/glutamate ratio increased significantly in the ketamine group, compared with placebo, specifically in the pgACC after 24 h. The glutamine/glutamate increase in the pgACC caused by ketamine at 24 h post infusion was reproduced in an enlarged sample (placebo, n=24; ketamine, n=20). Our results support a significant temporal and regional response in glutamine/glutamate ratios to a single subanesthetic dose of ketamine, which mirrors the time course of the antidepressant response and reversal of the molecular deficits in patients and which may be associated with the histoarchitectonical receptor fingerprints of the ACC subregions.
Collapse
Affiliation(s)
- Meng Li
- Clinical Affective Neuroimaging Laboratory, Leibniz Institute for Neurobiology, Otto von Guericke University, Magdeburg, Germany
- Department of Neurology, Otto von Guericke University, Magdeburg, Germany
| | - Liliana Ramona Demenescu
- Clinical Affective Neuroimaging Laboratory, Leibniz Institute for Neurobiology, Otto von Guericke University, Magdeburg, Germany
- Department of Neurology, Otto von Guericke University, Magdeburg, Germany
| | - Lejla Colic
- Clinical Affective Neuroimaging Laboratory, Leibniz Institute for Neurobiology, Otto von Guericke University, Magdeburg, Germany
- Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Coraline Danielle Metzger
- German Centre for Neurodegenerative Diseases (DZNE), Site Magdeburg, Germany
- Institute of Cognitive Neurology and Dementia Research (IKND), Magdeburg, Germany
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, Otto von Guericke University, Magdeburg, Germany
| | - Hans-Jochen Heinze
- Department of Neurology, Otto von Guericke University, Magdeburg, Germany
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, Otto von Guericke University, Magdeburg, Germany
| | - Johann Steiner
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, Otto von Guericke University, Magdeburg, Germany
| | - Oliver Speck
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- German Centre for Neurodegenerative Diseases (DZNE), Site Magdeburg, Germany
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Biomedical Magnetic Resonance, Otto von Guericke University, Magdeburg, Germany
| | - Anna Fejtova
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | | | - Martin Walter
- Clinical Affective Neuroimaging Laboratory, Leibniz Institute for Neurobiology, Otto von Guericke University, Magdeburg, Germany
- Leibniz Institute for Neurobiology, Magdeburg, Germany
- Centre for Behavioural Brain Sciences (CBBS), Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, Otto von Guericke University, Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| |
Collapse
|
13
|
Kanaan AS, Gerasch S, García-García I, Lampe L, Pampel A, Anwander A, Near J, Möller HE, Müller-Vahl K. Pathological glutamatergic neurotransmission in Gilles de la Tourette syndrome. Brain 2016; 140:218-234. [DOI: 10.1093/brain/aww285] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/31/2016] [Accepted: 09/12/2016] [Indexed: 11/13/2022] Open
|
14
|
Buonocore MH, Maddock RJ. Magnetic resonance spectroscopy of the brain: a review of physical principles and technical methods. Rev Neurosci 2016. [PMID: 26200810 DOI: 10.1515/revneuro-2015-0010] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Magnetic resonance spectroscopy (MRS) provides unique information about the neurobiological substrates of brain function in health and disease. However, many of the physical principles underlying MRS are distinct from those underlying magnetic resonance imaging, and they may not be widely understood by neuroscientists new to this methodology. This review describes these physical principles and many of the technical methods in current use for MRS experiments. A better understanding these principles and methods may help investigators select pulse sequences and quantification methods best suited to the aims of their research program and avoid pitfalls that can hamper new investigators in this field.
Collapse
|
15
|
Croarkin PE, Nakonezny PA, Wall CA, Murphy LL, Sampson SM, Frye MA, Port JD. Transcranial magnetic stimulation potentiates glutamatergic neurotransmission in depressed adolescents. Psychiatry Res 2016; 247:25-33. [PMID: 26651598 PMCID: PMC4716879 DOI: 10.1016/j.pscychresns.2015.11.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/10/2015] [Accepted: 11/15/2015] [Indexed: 01/07/2023]
Abstract
Abnormalities in glutamate neurotransmission may have a role in the pathophysiology of adolescent depression. The present pilot study examined changes in cortical glutamine/glutamate ratios in depressed adolescents receiving high-frequency repetitive transcranial magnetic stimulation. Ten adolescents with treatment-refractory major depressive disorder received up to 30 sessions of 10-Hz repetitive transcranial magnetic stimulation at 120% motor threshold with 3000 pulses per session applied to the left dorsolateral prefrontal cortex. Baseline, posttreatment, and 6-month follow-up proton magnetic resonance spectroscopy scans of the anterior cingulate cortex and left dorsolateral prefrontal cortex were collected at 3T with 8-cm(3) voxels. Glutamate metabolites were quantified with 2 distinct proton magnetic resonance spectroscopy sequences in each brain region. After repetitive transcranial magnetic stimulation and at 6 months of follow-up, glutamine/glutamate ratios increased in the anterior cingulate cortex and left dorsolateral prefrontal cortex with both measurements. The increase in the glutamine/glutamate ratio reached statistical significance with the TE-optimized PRESS sequence in the anterior cingulate cortex. Glutamine/glutamate ratios increased in conjunction with depressive symptom improvement. This reached statistical significance with the TE-optimized PRESS sequence in the left dorsolateral prefrontal cortex. High-frequency repetitive transcranial magnetic stimulation applied to the left dorsolateral prefrontal cortex may modulate glutamate neurochemistry in depressed adolescents.
Collapse
Affiliation(s)
- Paul E Croarkin
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, United States.
| | - Paul A Nakonezny
- Department of Clinical Sciences, Division of Biostatistics, UT Southwestern Medical Center, Dallas, Texas, United States
| | | | - Lauren L Murphy
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, United States
| | - Shirlene M Sampson
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, United States
| | - Mark A Frye
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, United States
| | - John D Port
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, United States; Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States
| |
Collapse
|
16
|
Birch R, Peet AC, Dehghani H, Wilson M. Influence of macromolecule baseline on 1 H MR spectroscopic imaging reproducibility. Magn Reson Med 2016; 77:34-43. [PMID: 26800478 PMCID: PMC5215417 DOI: 10.1002/mrm.26103] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/30/2015] [Accepted: 12/03/2015] [Indexed: 11/11/2022]
Abstract
Purpose Poorly characterized macromolecular (MM) and baseline artefacts are known to reduce metabolite quantitation accuracy in 1H MR spectroscopic imaging (MRSI). Increasing echo time (TE) and improvements in MM analysis schemes have both been proposed as strategies to improve metabolite measurement reliability. In this study, the influence of TE and two MM analysis schemes on MRSI reproducibility are investigated. Methods An experimentally acquired baseline was collected using an inversion recovery sequence (TI = 750 ms) and incorporated into the analysis method. Intrasubject reproducibility of MRSI scans, acquired at 3 Tesla, was assessed using metabolite coefficients of variance (COVs) for both experimentally acquired and simulated MM analysis schemes. In addition, the reproducibility of TE = 35 ms, 80 ms, and 144 ms was evaluated. Results TE = 80 ms was the most reproducible for singlet metabolites with COVs < 6% for total N‐acetyl‐aspartate, total creatine, and total choline; however, moderate multiplet dephasing was observed. Analysis incorporating the experimental baseline achieved higher Glu and Glx reproducibility at TE = 35 ms, and showed improvements over the simulated baseline, with higher efficacy for poorer data. Conclusion Overall, TE = 80 ms yielded the most reproducible singlet metabolite estimates. However, combined use of a short TE sequence and the experimental baseline may be preferred as a compromise between accuracy, multiplet dephasing, and T2 bias on metabolite estimates. Magn Reson Med 77:34–43, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
Collapse
Affiliation(s)
- Rebecca Birch
- PSIBS Doctoral Training Centre, University of Birmingham, United Kingdom.,Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, United Kingdom
| | - Andrew C Peet
- Department of Oncology, Birmingham Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom.,School of Cancer Sciences, University of Birmingham, United Kingdom
| | - Hamid Dehghani
- School of Computer Science, University of Birmingham, Kingdom
| | - Martin Wilson
- Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, United Kingdom
| |
Collapse
|
17
|
Bollmann S, Ghisleni C, Poil SS, Martin E, Ball J, Eich-Höchli D, Edden RAE, Klaver P, Michels L, Brandeis D, O'Gorman RL. Developmental changes in gamma-aminobutyric acid levels in attention-deficit/hyperactivity disorder. Transl Psychiatry 2015; 5:e589. [PMID: 26101852 PMCID: PMC4490289 DOI: 10.1038/tp.2015.79] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 04/27/2015] [Accepted: 05/04/2015] [Indexed: 12/20/2022] Open
Abstract
While the neurobiological basis and developmental course of attention-deficit/hyperactivity disorder (ADHD) have not yet been fully established, an imbalance between inhibitory/excitatory neurotransmitters is thought to have an important role in the pathophysiology of ADHD. This study examined the changes in cerebral levels of GABA+, glutamate and glutamine in children and adults with ADHD using edited magnetic resonance spectroscopy. We studied 89 participants (16 children with ADHD, 19 control children, 16 adults with ADHD and 38 control adults) in a subcortical voxel (children and adults) and a frontal voxel (adults only). ADHD adults showed increased GABA+ levels relative to controls (P = 0.048), while ADHD children showed no difference in GABA+ in the subcortical voxel (P > 0.1), resulting in a significant age by disorder interaction (P = 0.026). Co-varying for age in an analysis of covariance model resulted in a nonsignificant age by disorder interaction (P = 0.06). Glutamine levels were increased in children with ADHD (P = 0.041), but there was no significant difference in adults (P > 0.1). Glutamate showed no difference between controls and ADHD patients but demonstrated a strong effect of age across both groups (P < 0.001). In conclusion, patients with ADHD show altered levels of GABA+ in a subcortical voxel which change with development. Further, we found increased glutamine levels in children with ADHD, but this difference normalized in adults. These observed imbalances in neurotransmitter levels are associated with ADHD symptomatology and lend new insight in the developmental trajectory and pathophysiology of ADHD.
Collapse
Affiliation(s)
- S Bollmann
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland,Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zürich, Switzerland,Centre for Advanced Imaging, University of Queensland, Brisbane, QLD, Australia
| | - C Ghisleni
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland
| | - S-S Poil
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland
| | - E Martin
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland
| | - J Ball
- Department of Child and Adolescent Psychiatry, University of Zurich, Zürich, Switzerland
| | - D Eich-Höchli
- Psychiatric University Hospital, Zürich, Switzerland
| | - R A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA,F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - P Klaver
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland,Department of Psychology, University of Zurich, Zürich, Switzerland
| | - L Michels
- Institute of Neuroradiology, University Hospital of Zurich, Zürich, Switzerland
| | - D Brandeis
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland,Department of Child and Adolescent Psychiatry, University of Zurich, Zürich, Switzerland,Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health Mannheim, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - R L O'Gorman
- Center for MR-Research, University Children's Hospital Zurich, Zürich, Switzerland,Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland,Pediatric Research Center, University Children's Hospital Zurich, Zürich, Switzerland,Center for MR-Research, University Children's Hospital Zurich, Steinwiesstrasse 75, Zürich CH 8032, Switzerland. E-mail:
| |
Collapse
|
18
|
Wijtenburg SA, Yang S, Fischer BA, Rowland LM. In vivo assessment of neurotransmitters and modulators with magnetic resonance spectroscopy: application to schizophrenia. Neurosci Biobehav Rev 2015; 51:276-95. [PMID: 25614132 PMCID: PMC4427237 DOI: 10.1016/j.neubiorev.2015.01.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 01/02/2015] [Accepted: 01/08/2015] [Indexed: 12/28/2022]
Abstract
In vivo measurement of neurotransmitters and modulators is now feasible with advanced proton magnetic resonance spectroscopy ((1)H MRS) techniques. This review provides a basic tutorial of MRS, describes the methods available to measure brain glutamate, glutamine, γ-aminobutyric acid, glutathione, N-acetylaspartylglutamate, glycine, and serine at magnetic field strengths of 3T or higher, and summarizes the neurochemical findings in schizophrenia. Overall, (1)H MRS holds great promise for producing biomarkers that can serve as treatment targets, prediction of disease onset, or illness exacerbation in schizophrenia and other brain diseases.
Collapse
Affiliation(s)
- S Andrea Wijtenburg
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, PO Box 21247, Baltimore, MD 21228, USA.
| | - Shaolin Yang
- Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Street, Suite 512, Chicago, IL 60612, USA; Department of Radiology, University of Illinois at Chicago, 1601 W. Taylor Street, Suite 512, Chicago, IL 60612, USA; Department of Bioengineering, University of Illinois at Chicago, 1601 W. Taylor Street, Suite 512, Chicago, IL 60612, USA
| | - Bernard A Fischer
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, PO Box 21247, Baltimore, MD 21228, USA; Veterans Affairs Capital Network (VISN 5) Mental Illness Research, Education, and Clinical Center (MIRECC), Department of Veterans Affairs, 10 N. Greene Street, Baltimore, MD 21201, USA
| | - Laura M Rowland
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, PO Box 21247, Baltimore, MD 21228, USA; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA; Department of Psychology, University of Maryland, Baltimore County, Baltimore, MD 21228, USA
| |
Collapse
|
19
|
Craveiro M, Cudalbu C, Mlynárik V, Gruetter R. Optimized MEGA-SPECIAL for in vivo glutamine detection in the rat brain at 14.1 T. NMR IN BIOMEDICINE 2014; 27:1151-1158. [PMID: 25070114 DOI: 10.1002/nbm.3168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 04/04/2014] [Accepted: 06/22/2014] [Indexed: 06/03/2023]
Abstract
Glutamine has multiple roles in brain metabolism and its concentration can be altered in various pathological conditions. An accurate knowledge of its concentration is therefore highly desirable to monitor and study several brain disorders in vivo. However, in recent years, several MRS studies have reported conflicting glutamine concentrations in the human brain. A recent hypothesis for explaining these discrepancies is that a short T2 component of the glutamine signal may impact on its quantification at long echo times. The present study therefore aimed to investigate the impact of acquisition parameters on the quantified glutamine concentration using two different acquisition techniques, SPECIAL at ultra-short echo time and MEGA-SPECIAL at moderate echo time. For this purpose, MEGA-SPECIAL was optimized for the first time for glutamine detection. Based on the very good agreement of the glutamine concentration obtained between the two measurements, it was concluded that no impact of a short T2 component of the glutamine signal was detected.
Collapse
Affiliation(s)
- Mélanie Craveiro
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | | | | | | |
Collapse
|
20
|
Chowdhury FA, O'Gorman RL, Nashef L, Elwes RD, Edden RA, Murdoch JB, Barker GJ, Richardson MP. Investigation of glutamine and GABA levels in patients with idiopathic generalized epilepsy using MEGAPRESS. J Magn Reson Imaging 2014; 41:694-9. [PMID: 24585443 DOI: 10.1002/jmri.24611] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/11/2014] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Idiopathic generalized epilepsies (IGE) comprise a group of clinical syndromes associated with spike wave discharges, putatively linked to alterations in neurotransmission. The purpose of this study was to investigate whether patients with IGE have altered glutamine and γ-aminobutyric acid (GABA) levels indicative of altered excitatory and inhibitory neurotransmission in frontal regions. MATERIALS AND METHODS Single-voxel MEGA-edited PRESS magnetic resonance imaging (MRI) spectra were acquired from a 30-mL voxel in the dorsolateral prefrontal cortex in 13 patients with IGE (8 female) and 16 controls (9 female) at 3T. Metabolite concentrations were derived using LCModel. Differences between groups were investigated using an unpaired t-test. RESULTS Patients with IGE were found to have significantly higher glutamine than controls (P = 0.02). GABA levels were also elevated in patients with IGE (P = 0.03). CONCLUSION Patients with IGE have increased frontal glutamine and GABA compared with controls. Since glutamine has been suggested to act as a surrogate for metabolically active glutamate, it may represent a marker for excitatory neurotransmission.
Collapse
Affiliation(s)
- Fahmida A Chowdhury
- Department of Clinical Neuroscience Institute of Psychiatry, King's College London, London, UK
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Rae CD. A Guide to the Metabolic Pathways and Function of Metabolites Observed in Human Brain 1H Magnetic Resonance Spectra. Neurochem Res 2013; 39:1-36. [PMID: 24258018 DOI: 10.1007/s11064-013-1199-5] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 12/20/2022]
|
22
|
Near J, Andersson J, Maron E, Mekle R, Gruetter R, Cowen P, Jezzard P. Unedited in vivo detection and quantification of γ-aminobutyric acid in the occipital cortex using short-TE MRS at 3 T. NMR IN BIOMEDICINE 2013; 26:1353-62. [PMID: 23696182 DOI: 10.1002/nbm.2960] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/15/2013] [Accepted: 03/18/2013] [Indexed: 05/13/2023]
Abstract
Short-TE MRS has been proposed recently as a method for the in vivo detection and quantification of γ-aminobutyric acid (GABA) in the human brain at 3 T. In this study, we investigated the accuracy and reproducibility of short-TE MRS measurements of GABA at 3 T using both simulations and experiments. LCModel analysis was performed on a large number of simulated spectra with known metabolite input concentrations. Simulated spectra were generated using a range of spectral linewidths and signal-to-noise ratios to investigate the effect of varying experimental conditions, and analyses were performed using two different baseline models to investigate the effect of an inaccurate baseline model on GABA quantification. The results of these analyses indicated that, under experimental conditions corresponding to those typically observed in the occipital cortex, GABA concentration estimates are reproducible (mean reproducibility error, <20%), even when an incorrect baseline model is used. However, simulations indicate that the accuracy of GABA concentration estimates depends strongly on the experimental conditions (linewidth and signal-to-noise ratio). In addition to simulations, in vivo GABA measurements were performed using both spectral editing and short-TE MRS in the occipital cortex of 14 healthy volunteers. Short-TE MRS measurements of GABA exhibited a significant positive correlation with edited GABA measurements (R = 0.58, p < 0.05), suggesting that short-TE measurements of GABA correspond well with measurements made using spectral editing techniques. Finally, within-session reproducibility was assessed in the same 14 subjects using four consecutive short-TE GABA measurements in the occipital cortex. Across all subjects, the average coefficient of variation of these four GABA measurements was 8.7 ± 4.9%. This study demonstrates that, under some experimental conditions, short-TE MRS can be employed for the reproducible detection of GABA at 3 T, but that the technique should be used with caution, as the results are dependent on the experimental conditions.
Collapse
Affiliation(s)
- Jamie Near
- Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, QC, Canada; Department of Psychiatry, University of Oxford, Oxford, UK; FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | | | | | | | | | | |
Collapse
|
23
|
Wijtenburg SA, Gaston FE, Spieker EA, Korenic SA, Kochunov P, Hong LE, Rowland LM. Reproducibility of phase rotation STEAM at 3T: focus on glutathione. Magn Reson Med 2013; 72:603-9. [PMID: 24151202 DOI: 10.1002/mrm.24959] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/08/2013] [Accepted: 08/28/2013] [Indexed: 12/25/2022]
Abstract
PURPOSE The purpose of this study was to determine the reproducibility of a very short echo time (TE) phase rotation stimulated echo acquisition mode (STEAM) sequence at 3T with a focus on the detection of glutathione. METHODS Ten healthy subjects were scanned on two separate visits. Spectra were acquired from voxels placed in the anterior and posterior cingulates. Reproducibility was assessed using mean coefficients of variation (CVs) and mean absolute differences (ADs), and reliability was assessed using standard error of measurement (SEM) and intraclass correlations (ICCs). Phantoms containing glutathione and metabolites with overlapping resonances were scanned to test the validity of glutathione quantification. RESULTS Excellent reproducibility as illustrated by CVs ≤8.3% and ADs ≤11.6% for both regions was obtained for glutathione and other commonly reported metabolites. Reproducibility measures for γ-aminobutyric acid and glutamine were good overall with CVs ranging from 6.4%-10.5% and ADs ranging from 8.6%-15.5% for both regions. Glutathione absolute and relative reliability were very good (SEMs ≤9.9%) and fair (ICCs = 0.42-0.51), respectively. Phantom studies demonstrated the ability to accurately detect glutathione from other metabolites with overlapping resonances with great precision (R(2) = 0.99). CONCLUSION A very short TE phase rotation STEAM sequence proved reproducible for metabolites difficult to quantify but important for the study of psychiatric and neurological illness.
Collapse
Affiliation(s)
- S Andrea Wijtenburg
- Neuroimaging Research Program, Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
Glutamatergic correlates of gamma-band oscillatory activity during cognition: a concurrent ER-MRS and EEG study. Neuroimage 2013; 85 Pt 2:823-33. [PMID: 23891885 DOI: 10.1016/j.neuroimage.2013.07.049] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 07/12/2013] [Accepted: 07/18/2013] [Indexed: 11/21/2022] Open
Abstract
Frequency specific synchronisation of neuronal firing within the gamma-band (30-70 Hz) appears to be a fundamental correlate of both basic sensory and higher cognitive processing. In-vitro studies suggest that the neurochemical basis of gamma-band oscillatory activity is based on interactions between excitatory (i.e. glutamate) and inhibitory (i.e. GABA) neurotransmitter concentrations. However, the nature of the relationship between excitatory neurotransmitter concentration and changes in gamma band activity in humans remains undetermined. Here, we examine the links between dynamic glutamate concentration and the formation of functional gamma-band oscillatory networks. Using concurrently acquired event-related magnetic resonance spectroscopy and electroencephalography, during a repetition-priming paradigm, we demonstrate an interaction between stimulus type (object vs. abstract pictures) and repetition in evoked gamma-band oscillatory activity, and find that glutamate levels within the lateral occipital cortex, differ in response to these distinct stimulus categories. Importantly, we show that dynamic glutamate levels are related to the amplitude of stimulus evoked gamma-band (but not to beta, alpha or theta or ERP) activity. These results highlight the specific connection between excitatory neurotransmitter concentration and amplitude of oscillatory response, providing a novel insight into the relationship between the neurochemical and neurophysiological processes underlying cognition.
Collapse
|
25
|
Duarte JMN, Gruetter R. Glutamatergic and GABAergic energy metabolism measured in the rat brain by 13
C NMR spectroscopy at 14.1 T. J Neurochem 2013; 126:579-90. [DOI: 10.1111/jnc.12333] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 06/05/2013] [Accepted: 06/06/2013] [Indexed: 12/11/2022]
Affiliation(s)
- João M. N. Duarte
- Laboratory for Functional and Metabolic Imaging; École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
- Department of Radiology; University of Lausanne; Lausanne Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging; École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
- Department of Radiology; University of Lausanne; Lausanne Switzerland
- Department of Radiology; University of Geneva; Geneva Switzerland
| |
Collapse
|
26
|
Abstract
The purpose of this study is to review the MR spectroscopic literature regarding schizophrenia. However, as there are over 250 primary MRS articles and dozens of MRS review articles on the subject already, this study will take a different approach. First, the clinical features of schizophrenia will be described. The background neuroanatomy and biochemistry relevant to schizophrenia will be reviewed, as many readers of this journal are unlikely to be familiar with these fields. A current model of the abnormal neural circuitry in schizophrenia will be presented, and predictions extrapolated about relevant metabolite changes over time. Finally, the existing MRS literature will be reviewed in the context of our existing anatomical and chemical knowledge, and future MRS research directions will be elaborated.
Collapse
Affiliation(s)
- John D Port
- Department of Radiology, Mayo Clinic, Rochester, Minnesota; Department of Psychiatry, Mayo Clinic, Rochester, Minnesota, USA.
| | | |
Collapse
|
27
|
Gabbay V, Mao X, Klein RG, Ely BA, Babb JS, Panzer AM, Alonso CM, Shungu DC. Anterior cingulate cortex γ-aminobutyric acid in depressed adolescents: relationship to anhedonia. ACTA ACUST UNITED AC 2011; 69:139-49. [PMID: 21969419 DOI: 10.1001/archgenpsychiatry.2011.131] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONTEXT Anhedonia, a core symptom of major depressive disorder (MDD) and highly variable among adolescents with MDD, may involve alterations in the major inhibitory amino acid neurotransmitter system of γ-aminobutyric acid (GABA). OBJECTIVE To test whether anterior cingulate cortex (ACC) GABA levels, measured by proton magnetic resonance spectroscopy, are decreased in adolescents with MDD. The associations of GABA alterations with the presence and severity of anhedonia were explored. DESIGN Case-control, cross-sectional study using single-voxel proton magnetic resonance spectroscopy at 3 T. SETTING Two clinical research divisions at 2 teaching hospitals. PARTICIPANTS Twenty psychotropic medication-free adolescents with MDD (10 anhedonic, 12 female, aged 12-19 years) with episode duration of 8 weeks or more and 21 control subjects group matched for sex and age. MAIN OUTCOME MEASURES Anterior cingulate cortex GABA levels expressed as ratios relative to unsuppressed voxel tissue water (w) and anhedonia scores expressed as a continuous variable. RESULTS Compared with control subjects, adolescents with MDD had significantly decreased ACC GABA/w (t = 3.2; P < .003). When subjects with MDD were categorized based on the presence of anhedonia, only anhedonic patients had decreased GABA/w levels compared with control subjects (t = 4.08; P < .001; P(Tukey) < .001). Anterior cingulate cortex GABA/w levels were negatively correlated with anhedonia scores for the whole MDD group (r = -0.50; P = .02), as well as for the entire participant sample including the control subjects (r = -0.54; P < .001). Anterior cingulate cortex white matter was also significantly decreased in adolescents with MDD compared with controls (P = .04). CONCLUSIONS These findings suggest that GABA, the major inhibitory neurotransmitter in the brain, may be implicated in adolescent MDD and, more specifically, in those with anhedonia. In addition, use of a continuous rather than categorical scale of anhedonia, as in the present study, may permit greater specificity in evaluating this important clinical feature.
Collapse
Affiliation(s)
- Vilma Gabbay
- Department of Child and Adolescent Psychiatry, New York University Child Study Center, New York University Langone Medical Center, New York, NY 10016, USA.
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Duarte JMN, Lanz B, Gruetter R. Compartmentalized Cerebral Metabolism of [1,6-(13)C]Glucose Determined by in vivo (13)C NMR Spectroscopy at 14.1 T. FRONTIERS IN NEUROENERGETICS 2011; 3:3. [PMID: 21713114 PMCID: PMC3112327 DOI: 10.3389/fnene.2011.00003] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 05/17/2011] [Indexed: 11/13/2022]
Abstract
Cerebral metabolism is compartmentalized between neurons and glia. Although glial glycolysis is thought to largely sustain the energetic requirements of neurotransmission while oxidative metabolism takes place mainly in neurons, this hypothesis is matter of debate. The compartmentalization of cerebral metabolic fluxes can be determined by (13)C nuclear magnetic resonance (NMR) spectroscopy upon infusion of (13)C-enriched compounds, especially glucose. Rats under light α-chloralose anesthesia were infused with [1,6-(13)C]glucose and (13)C enrichment in the brain metabolites was measured by (13)C NMR spectroscopy with high sensitivity and spectral resolution at 14.1 T. This allowed determining (13)C enrichment curves of amino acid carbons with high reproducibility and to reliably estimate cerebral metabolic fluxes (mean error of 8%). We further found that TCA cycle intermediates are not required for flux determination in mathematical models of brain metabolism. Neuronal tricarboxylic acid cycle rate (V(TCA)) and neurotransmission rate (V(NT)) were 0.45 ± 0.01 and 0.11 ± 0.01 μmol/g/min, respectively. Glial V(TCA) was found to be 38 ± 3% of total cerebral oxidative metabolism, accounting for more than half of neuronal oxidative metabolism. Furthermore, glial anaplerotic pyruvate carboxylation rate (V(PC)) was 0.069 ± 0.004 μmol/g/min, i.e., 25 ± 1% of the glial TCA cycle rate. These results support a role of glial cells as active partners of neurons during synaptic transmission beyond glycolytic metabolism.
Collapse
Affiliation(s)
- João M N Duarte
- Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne Lausanne, Switzerland
| | | | | |
Collapse
|