1
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Achanta LB, Thomas DS, Housley GD, Rae CD. AMP-activated protein kinase activators have compound and concentration-specific effects on brain metabolism. J Neurochem 2024; 168:677-692. [PMID: 36977628 DOI: 10.1111/jnc.15815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023]
Abstract
AMP-activated protein kinase (AMPK) is a key sensor of energy balance playing important roles in the balancing of anabolic and catabolic activities. The high energy demands of the brain and its limited capacity to store energy indicate that AMPK may play a significant role in brain metabolism. Here, we activated AMPK in guinea pig cortical tissue slices, both directly with A769662 and PF 06409577 and indirectly with AICAR and metformin. We studied the resultant metabolism of [1-13C]glucose and [1,2-13C]acetate using NMR spectroscopy. We found distinct activator concentration-dependent effects on metabolism, which ranged from decreased metabolic pool sizes at EC50 activator concentrations with no expected stimulation in glycolytic flux to increased aerobic glycolysis and decreased pyruvate metabolism with certain activators. Further, activation with direct versus indirect activators produced distinct metabolic outcomes at both low (EC50) and higher (EC50 × 10) concentrations. Specific direct activation of β1-containing AMPK isoforms with PF 06409577 resulted in increased Krebs cycle activity, restoring pyruvate metabolism while A769662 increased lactate and alanine production, as well as labelling of citrate and glutamine. These results reveal a complex metabolic response to AMPK activators in brain beyond increased aerobic glycolysis and indicate that further research is warranted into their concentration- and mechanism-dependent impact.
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Affiliation(s)
- Lavanya B Achanta
- Neuroscience Research Australia, Barker St, Randwick, New South Wales, 2031, Australia
- Translational Neuroscience Facility, School of Biomedical Sciences, UNSW, Sydney, New South Wales, 2052, Australia
| | - Donald S Thomas
- Mark Wainwright Analytical Centre, UNSW, Sydney, New South Wales, 2052, Australia
| | - Gary D Housley
- Translational Neuroscience Facility, School of Biomedical Sciences, UNSW, Sydney, New South Wales, 2052, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Barker St, Randwick, New South Wales, 2031, Australia
- School of Psychology, UNSW, Sydney, New South Wales, 2052, Australia
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2
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Steuer AE, Raeber J, Simbuerger F, Dornbierer DA, Bosch OG, Quednow BB, Seifritz E, Kraemer T. Towards Extending the Detection Window of Gamma-Hydroxybutyric Acid-An Untargeted Metabolomics Study in Serum and Urine Following Controlled Administration in Healthy Men. Metabolites 2021; 11:metabo11030166. [PMID: 33809281 PMCID: PMC7998200 DOI: 10.3390/metabo11030166] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/08/2021] [Accepted: 03/10/2021] [Indexed: 12/28/2022] Open
Abstract
In forensic toxicology, gamma-hydroxybutyrate (GHB) still represents one of the most challenging drugs of abuse in terms of analytical detection and interpretation. Given its rapid elimination, the detection window of GHB in common matrices is short (maximum 12 h in urine). Additionally, the differentiation from naturally occurring endogenous GHB, is challenging. Thus, novel biomarkers to extend the detection window of GHB are urgently needed. The present study aimed at searching new potential biomarkers of GHB use by means of mass spectrometry (MS) metabolomic profiling in serum (up to 16.5 h) and urine samples (up to 8 h after intake) collected during a placebo-controlled crossover study in healthy men. MS data acquired by different analytical methods (reversed phase and hydrophilic interaction liquid chromatography; positive and negative electrospray ionization each) were filtered for significantly changed features applying univariate and mixed-effect model statistics. Complementary to a former study, conjugates of GHB with glycine, glutamate, taurine, carnitine and pentose (ribose) were identified in urine, with particularly GHB-pentose being promising for longer detection. None of the conjugates were detectable in serum. Therein, mainly energy metabolic substrates were identified, which may be useful for more detailed interpretation of underlying pathways but are too unspecific as biomarkers.
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Affiliation(s)
- Andrea E. Steuer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland; (J.R.); (F.S.); (D.A.D.); (T.K.)
- Correspondence: ; Tel.: +41-(0)4-4635-5679
| | - Justine Raeber
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland; (J.R.); (F.S.); (D.A.D.); (T.K.)
| | - Fabio Simbuerger
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland; (J.R.); (F.S.); (D.A.D.); (T.K.)
| | - Dario A. Dornbierer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland; (J.R.); (F.S.); (D.A.D.); (T.K.)
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, 8032 Zurich, Switzerland; (O.G.B.); (B.B.Q.); (E.S.)
| | - Oliver G. Bosch
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, 8032 Zurich, Switzerland; (O.G.B.); (B.B.Q.); (E.S.)
| | - Boris B. Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, 8032 Zurich, Switzerland; (O.G.B.); (B.B.Q.); (E.S.)
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, 8057 Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, 8032 Zurich, Switzerland; (O.G.B.); (B.B.Q.); (E.S.)
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, 8057 Zurich, Switzerland
- Zurich Center for Interdisciplinary Sleep Research (ZiS), University of Zurich, 8091 Zurich, Switzerland
| | - Thomas Kraemer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland; (J.R.); (F.S.); (D.A.D.); (T.K.)
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3
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Abstract
Patients with essential tremor, vocal tremor, torticollis, myoclonus-dystonia and posthypoxic myoclonus often benefit in a surprisingly rapid and robust manner from ingestion of a modest amount of alcohol (ethanol). Despite considerable investigation, the mechanism of ethanol’s ability to produce this effect remains a mystery. In this paper, we review the pharmacology of ethanol and its analogue GHB (or sodium oxybate), summarize the published literature of alcohol-responsive hyperkinetic movement disorders, and demonstrate videos of patients we have treated over the last fifteen years with either an ethanol challenge or with chronic sodium oxybate therapy. We then propose a novel explanation for this phenomenon—namely, that ingestion of modest doses of ethanol (or sodium oxybate) normalizes the aberrant motor networks underling these disorders. We propose that alcohol and its analogues improve clinical symptoms and their physiologic correlate by restoring the normal firing pattern of the major outflow pathways of the cerebellum (the Purkinje cells and deep cerebellar nuclei), We present evidence to support this hypothesis in animal models and in affected patients, and suggest future investigations to test this model.
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4
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Das A, Fröhlich D, Achanta LB, Rowlands BD, Housley GD, Klugmann M, Rae CD. L-Aspartate, L-Ornithine and L-Ornithine-L-Aspartate (LOLA) and Their Impact on Brain Energy Metabolism. Neurochem Res 2020; 45:1438-1450. [PMID: 32424601 DOI: 10.1007/s11064-020-03044-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/25/2020] [Accepted: 04/29/2020] [Indexed: 12/11/2022]
Abstract
L-Ornithine-L-aspartate (LOLA), a crystalline salt, is used primarily in the management of hepatic encephalopathy. The degree to which it might penetrate the brain, and the effects it might have on metabolism in brain are poorly understood. Here, to investigate the effects of LOLA on brain energy metabolism we incubated brain cortical tissue slices from guinea pig (Cavea porcellus) with the constituent amino acids of LOLA, L-ornithine or L-aspartate, as well as LOLA, in the presence of [1-13C]D-glucose and [1,2-13C]acetate; these labelled substrates are useful indicators of brain metabolic activity. L-Ornithine produced significant "sedative" effects on brain slice metabolism, most likely via conversion of ornithine to GABA via the ornithine aminotransferase pathway, while L-aspartate showed concentration-dependent excitatory effects. The metabolic effects of LOLA reflected a mix of these two different processes and were concentration-dependent. We also investigated the effect of an intraperitoneal bolus injection of L-ornithine, L-aspartate or LOLA on levels of metabolites in kidney, liver and brain cortex and brain stem in mice (C57Bl6J) 1 h later. No significant changes in metabolite levels were seen following the bolus injection of L-aspartate, most likely due to rapid metabolism of aspartate before reaching the target tissue. Brain cortex glutamate was decreased by L-ornithine but no other brain effects were observed with any other compound. Kidney levels of aspartate were increased after injection of L-ornithine and LOLA which may be due to interference by ornithine with the kidney urea cycle. It is likely that without optimising chronic intravenous infusion, LOLA has minimal impact on healthy brain energy metabolism due to systemic clearance and the blood - brain barrier.
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Affiliation(s)
- Abhijit Das
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia.,School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Dominik Fröhlich
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Kensington, 2052, Australia
| | - Lavanya B Achanta
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Kensington, 2052, Australia
| | - Benjamin D Rowlands
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Kensington, 2052, Australia
| | - Gary D Housley
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Kensington, 2052, Australia
| | - Matthias Klugmann
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Kensington, 2052, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia. .,School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia.
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5
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Ki Y, Lim C. Sleep-promoting effects of threonine link amino acid metabolism in Drosophila neuron to GABAergic control of sleep drive. eLife 2019; 8:40593. [PMID: 31313987 PMCID: PMC6636906 DOI: 10.7554/elife.40593] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 06/27/2019] [Indexed: 01/09/2023] Open
Abstract
Emerging evidence indicates the role of amino acid metabolism in sleep regulation. Here we demonstrate sleep-promoting effects of dietary threonine (SPET) in Drosophila. Dietary threonine markedly increased daily sleep amount and decreased the latency to sleep onset in a dose-dependent manner. High levels of synaptic GABA or pharmacological activation of metabotropic GABA receptors (GABAB-R) suppressed SPET. By contrast, synaptic blockade of GABAergic neurons or transgenic depletion of GABAB-R in the ellipsoid body R2 neurons enhanced sleep drive non-additively with SPET. Dietary threonine reduced GABA levels, weakened metabotropic GABA responses in R2 neurons, and ameliorated memory deficits in plasticity mutants. Moreover, genetic elevation of neuronal threonine levels was sufficient for facilitating sleep onset. Taken together, these data define threonine as a physiologically relevant, sleep-promoting molecule that may intimately link neuronal metabolism of amino acids to GABAergic control of sleep drive via the neuronal substrate of sleep homeostasis. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Yoonhee Ki
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Chunghun Lim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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6
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Lee HS, Seo C, Kim YA, Park M, Choi B, Ji M, Lee S, Paik MJ. Metabolomic study of polyamines in rat urine following intraperitoneal injection of γ-hydroxybutyric acid. Metabolomics 2019; 15:58. [PMID: 30941522 DOI: 10.1007/s11306-019-1517-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Recently, illegal abuse of γ-hydroxybutyric acid (GHB) has increased in drug-facilitated crimes, but the determination of GHB exposure and intoxication is difficult due to rapid metabolism of GHB. Its biochemical mechanism has not been completely investigated. And a metabolomic study by polyamine profile and pattern analyses was not performed in rat urine following intraperitoneal injection with GHB. OBJECTIVES Urinary polyamine (PA) profiling by gas chromatography-tandem mass spectrometry was performed to monitor an altered PA according to GHB administration. METHODS Polyamine profiling analysis by gas chromatography-mass spectrometry combined with star pattern recognition analysis was performed in this study. The multivariate statistical analysis was used to evaluate discrimination among control and GHB administration groups. RESULTS Six polyamines were determined in control, single and multiple GHB administration groups. Star pattern showed distorted hexagonal shapes with characteristic and readily distinguishable patterns for each group. N1-Acetylspermine (p < 0.001), putrescine (p < 0.006), N1-acetylspermidine (p < 0.009), and spermine (p < 0.027) were significantly increased in single administration group but were significantly lower in the multiple administration group than in the control group. N1-Acetylspermine was the main polyamine for discrimination among control, single and multiple administration groups. Spermine showed similar levels in single and multiple administration groups. CONCLUSIONS The polyamine metabolic pattern was monitored in GHB administration groups. N1-Acetylspermine and spermine were evaluated as potential biomarkers of GHB exposure and addiction.
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Affiliation(s)
- Hyeon-Seong Lee
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Chan Seo
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Young-A Kim
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Meejung Park
- National Forensic Service, 10 Ipchoon-ro, Wonju, Kangwon-do, 220-170, Republic of Korea
| | - Boyeon Choi
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea
| | - Moongi Ji
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Sooyeun Lee
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea.
| | - Man-Jeong Paik
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, 540-950, Republic of Korea.
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7
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Steuer AE, Raeber J, Steuer C, Boxler MI, Dornbierer DA, Bosch OG, Quednow BB, Seifritz E, Kraemer T. Identification of new urinary gamma‐hydroxybutyric acid markers applying untargeted metabolomics analysis following placebo‐controlled administration to humans. Drug Test Anal 2019; 11:813-823. [DOI: 10.1002/dta.2558] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Andrea E. Steuer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic MedicineUniversity of Zurich Switzerland
| | - Justine Raeber
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic MedicineUniversity of Zurich Switzerland
| | - Christian Steuer
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical SciencesSwiss Federal Institute of Technology (ETH) Switzerland
| | - Martina I. Boxler
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic MedicineUniversity of Zurich Switzerland
| | - Dario A. Dornbierer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic MedicineUniversity of Zurich Switzerland
- Institute of Pharmacology and ToxicologyUniversity of Zürich Switzerland
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric HospitalUniversity of Zürich Switzerland
- Zürich Center for interdisciplinary Sleep Research (ZiS)University of Zürich Switzerland
| | - Oliver G. Bosch
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric HospitalUniversity of Zürich Switzerland
| | - Boris B. Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric HospitalUniversity of Zürich Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric HospitalUniversity of Zürich Switzerland
- Zürich Center for interdisciplinary Sleep Research (ZiS)University of Zürich Switzerland
| | - Thomas Kraemer
- Department of Forensic Pharmacology & Toxicology, Zurich Institute of Forensic MedicineUniversity of Zurich Switzerland
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8
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Bosch OG, Esposito F, Havranek MM, Dornbierer D, von Rotz R, Staempfli P, Quednow BB, Seifritz E. Gamma-Hydroxybutyrate Increases Resting-State Limbic Perfusion and Body and Emotion Awareness in Humans. Neuropsychopharmacology 2017; 42:2141-2151. [PMID: 28561068 PMCID: PMC5603804 DOI: 10.1038/npp.2017.110] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/04/2017] [Accepted: 05/25/2017] [Indexed: 12/15/2022]
Abstract
Gamma-hydroxybutyrate (GHB) is a GHB-/GABA-B receptor agonist inducing a broad spectrum of subjective effects including euphoria, disinhibition, and enhanced vitality. It is used as treatment for neuropsychiatric disorders including narcolepsy and alcohol withdrawal, but is also a drug of abuse. Non-medical users report enhancement of body and emotion awareness during intoxication. However, the neuronal underpinnings of such awareness alterations under GHB are unknown so far. The assessment of regional cerebral blood flow (rCBF) by pharmacological magnetic resonance imaging (phMRI) enables the elucidation of drug-induced functional brain alterations. Thus, we assessed the effects of GHB (35 mg/kg p.o.) in 17 healthy males on rCBF and subjective drug effects, using a placebo-controlled, double-blind, randomized, cross-over design employing arterial spin labeling phMRI. Compared to placebo, GHB increased subjective ratings for body and emotion awareness, and for dizziness (p<0.01-0.001, Bonferroni-corrected). A whole-brain analysis showed increased rCBF in the bilateral anterior cingulate cortex (ACC) and the right anterior insula under GHB (p<0.05, cluster-corrected). ACC and insula rCBF are correlated with relaxation, and body and emotion awareness (p<0.05-0.001, uncorrected). Interaction analyses revealed that GHB-induced increase of body awareness was accompanied by increased rCBF in ACC, whereas relaxation under GHB was accompanied by elevated rCBF in right anterior insula (p<0.05, uncorrected). In conclusion, enhancement of emotion and body awareness, and increased perfusion of insula and ACC bears implications both for the properties of GHB as a drug of abuse as well as for its putative personalized potential for specific therapeutic indications in affective disorders.
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Affiliation(s)
- Oliver G Bosch
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland,Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland,Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, Zurich CH-8032, Switzerland, Tel: +41 44 384 2357, Fax: +41 44 383 4456, E-mail:
| | - Fabrizio Esposito
- Department of Medicine, Surgery and Dentistry ‘Scuola Medica Salernitana’, University of Salerno, Baronissi, Italy
| | - Michael M Havranek
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Dario Dornbierer
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland,Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Robin von Rotz
- Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Philipp Staempfli
- MR-Center of the Department of Psychiatry, Psychotherapy and Psychosomatics and the Department of Child and Adolescent Psychiatry, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Boris B Quednow
- Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland,Neuroscience Center Zurich, Research Group Disorders of the Nervous System, University and ETH Zurich, Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland,Neuroscience Center Zurich, Research Group Disorders of the Nervous System, University and ETH Zurich, Zurich, Switzerland
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9
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Achanta LB, Rowlands BD, Thomas DS, Housley GD, Rae CD. β-Hydroxybutyrate Boosts Mitochondrial and Neuronal Metabolism but is not Preferred Over Glucose Under Activated Conditions. Neurochem Res 2017; 42:1710-1723. [DOI: 10.1007/s11064-017-2228-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/06/2017] [Accepted: 03/09/2017] [Indexed: 12/21/2022]
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10
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Rowlands BD, Klugmann M, Rae CD. Acetate metabolism does not reflect astrocytic activity, contributes directly to GABA synthesis, and is increased by silent information regulator 1 activation. J Neurochem 2017; 140:903-918. [PMID: 27925207 DOI: 10.1111/jnc.13916] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
[13 C]Acetate is known to label metabolites preferentially in astrocytes rather than neurons and it has consequently been used as a marker for astrocytic activity. Recent discoveries suggest that control of acetate metabolism and its contributions to the synthesis of metabolites in brain is not as simple as first thought. Here, using a Guinea pig brain cortical tissue slice model metabolizing [1-13 C]D-glucose and [1,2-13 C]acetate, we investigated control of acetate metabolism and the degree to which it reflects astrocytic activity. Using a range of [1,2-13 C]acetate concentrations, we found that acetate is a poor substrate for metabolism and will inhibit metabolism of itself and of glucose at concentrations in excess of 2 mmol/L. By activating astrocytes using potassium depolarization, we found that use of [1,2-13 C]acetate to synthesize glutamine decreases significantly under these conditions showing that acetate metabolism does not necessarily reflect astrocytic activity. By blocking synthesis of glutamine using methionine sulfoximine, we found that significant amount of [1,2-13 C]acetate are still incorporated into GABA and its metabolic precursors in neurons, with around 30% of the GABA synthesized from [1,2-13 C]acetate likely to be made directly in neurons rather than from glutamine supplied by astrocytes. Finally, to test whether activity of the acetate metabolizing enzyme acetyl-CoA synthetase is under acetylation control in the brain, we incubated slices with the AceCS1 deacetylase silent information regulator 1 (SIRT1) activator SRT 1720 and showed consequential increased incorporation of [1,2-13 C]acetate into metabolites. Taken together, these data show that acetate metabolism is not directly nor exclusively related to astrocytic metabolic activity, that use of acetate is related to enzyme acetylation and that acetate is directly metabolized to a significant degree in GABAergic neurons. Changes in acetate metabolism should be interpreted as modulation of metabolism through changes in cellular energetic status via altered enzyme acetylation levels rather than simply as an adjustment of glial-neuronal metabolic activity.
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Affiliation(s)
- Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Matthias Klugmann
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, NSW, Australia.,School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
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11
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Kamal RM, van Noorden MS, Franzek E, Dijkstra BAG, Loonen AJM, De Jong CAJ. The Neurobiological Mechanisms of Gamma-Hydroxybutyrate Dependence and Withdrawal and Their Clinical Relevance: A Review. Neuropsychobiology 2016; 73:65-80. [PMID: 27003176 DOI: 10.1159/000443173] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 11/29/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVE x03B3;-Hydroxybutyrate (GHB) has gained popularity as a drug of abuse. In the Netherlands the number of patients in treatment for GHB dependence has increased sharply. Clinical presentation of GHB withdrawal can be life threatening. We aim, through this overview, to explore the neurobiological pathways causing GHB dependency and withdrawal, and their implications for treatment choices. METHODS In this work we review the literature discussing the findings from animal models to clinical studies focused on the neurobiological pathways of endogenous but mainly exogenous GHB. RESULTS Chronic abuse of GHB exerts multifarious neurotransmitter and neuromodulator effects on x03B3;-aminobutyric acid (GABA), glutamate, dopamine, serotonin, norepinephrine and cholinergic systems. Moreover, important effects on neurosteroidogenesis and oxytocin release are wielded. GHB acts mainly via a bidirectional effect on GABAB receptors (GABABR; subunits GABAB1 and GABAB2), depending on the subunit of the GIRK (G-protein-dependent ion inwardly rectifying potassium) channel involved, and an indirect effect of the cortical and limbic inputs outside the nucleus accumbens. GHB also activates a specific GHB receptor and β1-subunits of α4-GABAAR. Reversing this complex interaction of neurobiological mechanisms by the abrupt cessation of GHB use results in a withdrawal syndrome with a diversity of symptoms of different intensity, depending on the pattern of GHB abuse. CONCLUSION The GHB withdrawal symptoms cannot be related to a single mechanism or neurological pathway, which implies that different medication combinations are needed for treatment. A single drug class, such as benzodiazepines, gabapentin or antipsychotics, is unlikely to be sufficient to avoid life-threatening complications. Detoxification by means of titration and tapering of pharmaceutical GHB can be considered as a promising treatment that could make polypharmacy redundant.
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Affiliation(s)
- Rama M Kamal
- Nijmegen Institute for Scientist-Practitioners in Addiction (NISPA), Nijmegen, The Netherlands
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12
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Furlong TM, Duncan JR, Corbit LH, Rae CD, Rowlands BD, Maher AD, Nasrallah FA, Milligan CJ, Petrou S, Lawrence AJ, Balleine BW. Toluene inhalation in adolescent rats reduces flexible behaviour in adulthood and alters glutamatergic and GABAergic signalling. J Neurochem 2016; 139:806-822. [PMID: 27696399 DOI: 10.1111/jnc.13858] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 09/15/2016] [Accepted: 09/18/2016] [Indexed: 12/24/2022]
Abstract
Toluene is a commonly abused inhalant that is easily accessible to adolescents. Despite the increasing incidence of use, our understanding of its long-term impact remains limited. Here, we used a range of techniques to examine the acute and chronic effects of toluene exposure on glutameteric and GABAergic function, and on indices of psychological function in adult rats after adolescent exposure. Metabolomics conducted on cortical tissue established that acute exposure to toluene produces alterations in cellular metabolism indicative of a glutamatergic and GABAergic profile. Similarly, in vitro electrophysiology in Xenopus oocytes found that acute toluene exposure reduced NMDA receptor signalling. Finally, in an adolescent rodent model of chronic intermittent exposure to toluene (10 000 ppm), we found that, while toluene exposure did not affect initial learning, it induced a deficit in updating that learning when response-outcome relationships were reversed or degraded in an instrumental conditioning paradigm. There were also group differences when more effort was required to obtain the reward; toluene-exposed animals were less sensitive to progressive ratio schedules and to delayed discounting. These behavioural deficits were accompanied by changes in subunit expression of both NMDA and GABA receptors in adulthood, up to 10 weeks after the final exposure to toluene in the hippocampus, prefrontal cortex and ventromedial striatum; regions with recognized roles in behavioural flexibility and decision-making. Collectively, our data suggest that exposure to toluene is sufficient to induce adaptive changes in glutamatergic and GABAergic systems and in adaptive behaviour that may underlie the deficits observed following adolescent inhalant abuse, including susceptibility to further drug-use.
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Affiliation(s)
- Teri M Furlong
- Brain & Mind Centre, University of Sydney, Sydney, New South Wales, Australia.,School of Psychology, University of Sydney, Sydney, New South Wales, Australia
| | - Jhodie R Duncan
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
| | - Laura H Corbit
- School of Psychology, University of Sydney, Sydney, New South Wales, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,School of Medical Sciences, University of NSW, Kensington, New South Wales, Australia
| | - Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,School of Medical Sciences, University of NSW, Kensington, New South Wales, Australia
| | - Anthony D Maher
- Neuroscience Research Australia, Randwick, New South Wales, Australia
| | | | - Carol J Milligan
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Andrew J Lawrence
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Bernard W Balleine
- Brain & Mind Centre, University of Sydney, Sydney, New South Wales, Australia.,School of Psychology, University of NSW, Kensington, New South Wales, Australia
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13
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Comprehensive Application of Time-of-flight Secondary Ion Mass Spectrometry (TOF-SIMS) for Ionic Imaging and Bio-energetic Analysis of Club Drug-induced Cognitive Deficiency. Sci Rep 2015; 5:18420. [PMID: 26674573 PMCID: PMC4682059 DOI: 10.1038/srep18420] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 11/17/2015] [Indexed: 12/15/2022] Open
Abstract
Excessive exposure to club drug (GHB) would cause cognitive dysfunction in which impaired hippocampal Ca2+-mediated neuroplasticity may correlate with this deficiency. However, the potential changes of in vivo Ca2+ together with molecular machinery engaged in GHB-induced cognitive dysfunction has never been reported. This study aims to determine these changes in bio-energetic level through ionic imaging, spectrometric, biochemical, morphological, as well as behavioral approaches. Adolescent rats subjected to GHB were processed for TOF-SIMS, immunohistochemistry, biochemical assay, together with Morris water maze to detect the ionic, molecular, neurochemical, and behavioral changes of GHB-induced cognitive dysfunction, respectively. Extent of oxidative stress and bio-energetics were assessed by levels of lipid peroxidation, Na+/K+ ATPase, cytochrome oxidase, and [14C]-2-deoxyglucose activity. Results indicated that in GHB intoxicated rats, decreased Ca2+ imaging and reduced NMDAR1, nNOS, and p-CREB reactivities were detected in hippocampus. Depressed Ca2+-mediated signaling corresponded well with intense oxidative stress, diminished Na+/K+ ATPase, reduced COX, and decreased 2-DG activity, which all contributes to the development of cognitive deficiency. As impaired Ca2+-mediated signaling and oxidative stress significantly contribute to GHB-induced cognitive dysfunction, delivering agent(s) that improves hippocampal bio-energetics may thus serve as a promising strategy to counteract the club drug-induced cognitive dysfunction emerging in our society nowadays.
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14
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Salminen A, Jouhten P, Sarajärvi T, Haapasalo A, Hiltunen M. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease. Neurochem Int 2015; 92:13-24. [PMID: 26617286 DOI: 10.1016/j.neuint.2015.11.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/16/2015] [Accepted: 11/18/2015] [Indexed: 12/21/2022]
Abstract
We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis.
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Affiliation(s)
- Antero Salminen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland.
| | - Paula Jouhten
- VTT Technical Research Centre of Finland, FIN-00014 Helsinki, Finland; EMBL European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Timo Sarajärvi
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, Neulaniementie 2, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, P.O. Box 100, FI-70029 KYS, Finland
| | - Mikko Hiltunen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, P.O. Box 100, FI-70029 KYS, Finland; Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland
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15
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Zaitsu K, Hayashi Y, Kusano M, Tsuchihashi H, Ishii A. Application of metabolomics to toxicology of drugs of abuse: A mini review of metabolomics approach to acute and chronic toxicity studies. Drug Metab Pharmacokinet 2015; 31:21-26. [PMID: 26613805 DOI: 10.1016/j.dmpk.2015.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 12/24/2022]
Abstract
Metabolomics has been widely applied to toxicological fields, especially to elucidate the mechanism of action of toxicity. In this review, metabolomics application with focus on the studies of chronic and acute toxicities of drugs of abuse like stimulants, opioids and the recently-distributed designer drugs will be presented in addition to an outline of basic analytical techniques used in metabolomics. Limitation of metabolomics studies and future perspectives will be also provided.
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Affiliation(s)
- Kei Zaitsu
- Department of Legal Medicine & Bioethics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Yumi Hayashi
- Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya 461-8673, Japan.
| | - Maiko Kusano
- Department of Legal Medicine & Bioethics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - Hitoshi Tsuchihashi
- Department of Legal Medicine & Bioethics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - Akira Ishii
- Department of Legal Medicine & Bioethics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
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16
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Rae C, Nasrallah FA, Balcar VJ, Rowlands BD, Johnston GAR, Hanrahan JR. Metabolomic Approaches to Defining the Role(s) of GABAρ Receptors in the Brain. J Neuroimmune Pharmacol 2015; 10:445-56. [PMID: 25577264 DOI: 10.1007/s11481-014-9579-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Accepted: 12/26/2014] [Indexed: 10/24/2022]
Abstract
The inhibitory neurotransmitter γ-aminobutyric acid (GABA) acts through various types of receptors in the central nervous system. GABAρ receptors, defined by their characteristic pharmacology and presence of ρ subunits in the channel structure, are poorly understood and their role in the cortex is ill-defined. Here, we used a targeted pharmacological, NMR-based functional metabolomic approach in Guinea pig brain cortical tissue slices to identify a distinct role for these receptors. We compared metabolic fingerprints generated by a range of ligands active at GABAρ and included these in a principal components analysis with a library of other metabolic fingerprints obtained using ligands active at GABAA and GABAB, with inhibitors of GABA uptake and with compounds acting to inhibit enzymes active in the GABAergic system. This enabled us to generate a metabolic "footprint" of the GABAergic system which revealed classes of metabolic activity associated with GABAρ which are distinct from other GABA receptors. Antagonised GABAρ produce large metabolic effects at extrasynaptic sites suggesting they may be involved in tonic inhibition.
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Affiliation(s)
- Caroline Rae
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia,
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17
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Rowlands BD, Lau CL, Ryall JG, Thomas DS, Klugmann M, Beart PM, Rae CD. Silent information regulator 1 modulator resveratrol increases brain lactate production and inhibits mitochondrial metabolism, whereas SRT1720 increases oxidative metabolism. J Neurosci Res 2015; 93:1147-56. [PMID: 25677687 DOI: 10.1002/jnr.23570] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/16/2015] [Accepted: 01/16/2015] [Indexed: 12/26/2022]
Abstract
Silent information regulators (SIRTs) have been shown to deacetylate a range of metabolic enzymes, including those in glycolysis and the Krebs cycle, and thus alter their activity. SIRTs require NAD(+) for their activity, linking cellular energy status to enzyme activity. To examine the impact of SIRT1 modulation on oxidative metabolism, this study tests the effect of ligands that are either SIRT-activating compounds (resveratrol and SRT1720) or SIRT inhibitors (EX527) on the metabolism of (13)C-enriched substrates by guinea pig brain cortical tissue slices with (13)C and (1)H nuclear magnetic resonance spectroscopy. Resveratrol increased lactate labeling but decreased incorporation of (13)C into Krebs cycle intermediates, consistent with effects on AMPK and inhibition of the F0/F1-ATPase. By testing with resveratrol that was directly applied to astrocytes with a Seahorse analyzer, increased glycolytic shift and increased mitochondrial proton leak resulting from interactions of resveratrol with the mitochondrial electron transport chain were revealed. SRT1720, by contrast, stimulated incorporation of (13)C into Krebs cycle intermediates and reduced incorporation into lactate, although the inhibitor EX527 paradoxically also increased Krebs cycle (13)C incorporation. In summary, the various SIRT1 modulators show distinct acute effects on oxidative metabolism. The strong effects of resveratrol on the mitochondrial respiratory chain and on glycolysis suggest that caution should be used in attempts to increase bioavailability of this compound in the CNS.
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Affiliation(s)
- Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
| | - Chew Ling Lau
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - James G Ryall
- Stem Cell Metabolism and Regenerative Medicine Group, Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donald S Thomas
- Mark Wainwright Analytical Centre, The University of New South Wales, Randwick, New South Wales, Australia
| | - Matthias Klugmann
- Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
| | - Philip M Beart
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
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18
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19
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GHB receptor targets in the CNS: Focus on high-affinity binding sites. Biochem Pharmacol 2014; 87:220-8. [DOI: 10.1016/j.bcp.2013.10.028] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/29/2013] [Accepted: 10/29/2013] [Indexed: 12/13/2022]
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20
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Rae C, Balcar VJ. A Chip Off the Old Block: The Brain Slice as a Model for Metabolic Studies of Brain Compartmentation and Neuropharmacology. BRAIN ENERGY METABOLISM 2014. [DOI: 10.1007/978-1-4939-1059-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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21
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Rae CD, Davidson JE, Maher AD, Rowlands BD, Kashem MA, Nasrallah FA, Rallapalli SK, Cook JM, Balcar VJ. Ethanol, not detectably metabolized in brain, significantly reduces brain metabolism, probably via action at specific GABA(A) receptors and has measureable metabolic effects at very low concentrations. J Neurochem 2013; 129:304-14. [PMID: 24313287 DOI: 10.1111/jnc.12634] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 11/12/2013] [Accepted: 12/04/2013] [Indexed: 11/28/2022]
Abstract
Ethanol is a known neuromodulatory agent with reported actions at a range of neurotransmitter receptors. Here, we measured the effect of alcohol on metabolism of [3-¹³C]pyruvate in the adult Guinea pig brain cortical tissue slice and compared the outcomes to those from a library of ligands active in the GABAergic system as well as studying the metabolic fate of [1,2-¹³C]ethanol. Analyses of metabolic profile clusters suggest that the significant reductions in metabolism induced by ethanol (10, 30 and 60 mM) are via action at neurotransmitter receptors, particularly α4β3δ receptors, whereas very low concentrations of ethanol may produce metabolic responses owing to release of GABA via GABA transporter 1 (GAT1) and the subsequent interaction of this GABA with local α5- or α1-containing GABA(A)R. There was no measureable metabolism of [1,2-¹³C]ethanol with no significant incorporation of ¹³C from [1,2-¹³C]ethanol into any measured metabolite above natural abundance, although there were measurable effects on total metabolite sizes similar to those seen with unlabelled ethanol.
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Affiliation(s)
- Caroline D Rae
- Neuroscience Research Australia, and Brain Sciences UNSW, Randwick, NSW, Australia
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22
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Absalom N, Eghorn LF, Villumsen IS, Karim N, Bay T, Olsen JV, Knudsen GM, Bräuner-Osborne H, Frølund B, Clausen RP, Chebib M, Wellendorph P. α4βδ GABA(A) receptors are high-affinity targets for γ-hydroxybutyric acid (GHB). Proc Natl Acad Sci U S A 2012; 109:13404-9. [PMID: 22753476 PMCID: PMC3421209 DOI: 10.1073/pnas.1204376109] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
γ-Hydroxybutyric acid (GHB) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. However, the mechanistic links between these lines of data are unknown. To identify molecular targets for specific GHB high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several GABA(A) receptor subunits as possible candidates. A subsequent functional screening of various recombinant GABA(A) receptors in Xenopus laevis oocytes using the two-electrode voltage clamp technique showed GHB to be a partial agonist at αβδ- but not αβγ-receptors, proving that the δ-subunit is essential for potency and efficacy. GHB showed preference for α4 over α(1,2,6)-subunits and preferably activated α4β1δ (EC(50) = 140 nM) over α4β(2/3)δ (EC(50) = 8.41/1.03 mM). Introduction of a mutation, α4F71L, in α4β1(δ)-receptors completely abolished GHB but not GABA function, indicating nonidentical binding sites. Radioligand binding studies using the specific GHB radioligand [(3)H](E,RS)-(6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid showed a 39% reduction (P = 0.0056) in the number of binding sites in α4 KO brain tissue compared with WT controls, corroborating the direct involvement of the α4-subunit in high-affinity GHB binding. Our data link specific GHB forebrain binding sites with α4-containing GABA(A) receptors and postulate a role for extrasynaptic α4δ-containing GABA(A) receptors in GHB pharmacology and physiology. This finding will aid in elucidating the molecular mechanisms behind the proposed function of GHB as a neurotransmitter and its unique therapeutic effects in narcolepsy and alcoholism.
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Affiliation(s)
- Nathan Absalom
- Faculty of Pharmacy A15, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Laura F. Eghorn
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Inge S. Villumsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Nasiara Karim
- Faculty of Pharmacy A15, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Tina Bay
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jesper V. Olsen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; and
| | - Gitte M. Knudsen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging (Cimbi), Rigshospitalet and University of Copenhagen, 2100 Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Rasmus P. Clausen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Mary Chebib
- Faculty of Pharmacy A15, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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23
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24
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van Amsterdam JGC, Brunt TM, McMaster MTB, Niesink RJM. Possible long-term effects of γ-hydroxybutyric acid (GHB) due to neurotoxicity and overdose. Neurosci Biobehav Rev 2012; 36:1217-27. [PMID: 22342779 DOI: 10.1016/j.neubiorev.2012.02.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/24/2012] [Accepted: 02/02/2012] [Indexed: 11/17/2022]
Abstract
In several countries, including the Netherlands, the use of GHB seems to be rising. GHB is regarded by recreational users as an innocent drug without any side effects. Recently, the number of patients in treatment due to GHB addiction sharply increased. In addition, various studies report incidents following risky GHB use or GHB overdosing. Other sedative drugs, like ketamine and alcohol have been shown to result in unintended neurotoxic harm at the level of memory and cognitive function. As outlined in the present review, GHB and ketamine have a common mode of action, which suggests that GHB may also lead to similar neurotoxicity as ketamine. GHB overdosing, as well as binge drinking (and high ketamine doses), induce profound coma which is probably neurotoxic for the brain especially in the maturing brain of young adults. It is therefore advocated to investigate possible long-term neurotoxic effects in recreational GHB users e.g. by studying the residual effects on cognition and memory.
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Affiliation(s)
- Jan G C van Amsterdam
- National Institute of Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
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25
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Rat brain slices oxidize glucose at high rates: a (13)C NMR study. Neurochem Int 2011; 59:1145-54. [PMID: 22067134 DOI: 10.1016/j.neuint.2011.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 10/11/2011] [Accepted: 10/21/2011] [Indexed: 11/24/2022]
Abstract
Since glucose is the main cerebral substrate, we have characterized the metabolism of various (13)C glucose isotopomers in rat brain slices. For this, we have used our cellular metabolomic approach that combines enzymatic and carbon 13 NMR techniques with mathematical models of metabolic pathways. We identified the fate and the pathways of the conversion of glucose carbons into various products (pyruvate, lactate, alanine, aspartate, glutamate, GABA, glutamine and CO(2)) and determined absolute fluxes through pathways of glucose metabolism. After 60 min of incubation, lactate and CO(2) were the main end-products of the metabolism of glucose which was avidly metabolized by the slices. Lactate was also used at high rates by the slices and mainly converted into CO(2). High values of flux through pyruvate carboxylase, which were similar with glucose and lactate as substrate, were observed. The addition of glutamine, but not of acetate, stimulated pyruvate carboxylation, the conversion of glutamate into succinate and fluxes through succinate dehydrogenase, malic enzyme, glutamine synthetase and aspartate aminotransferase. It is concluded that, unlike brain cells in culture, and consistent with high fluxes through PDH and enzymes of the tricarboxylic acid cycle, rat brain slices oxidized both glucose and lactate at high rates.
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26
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Roiko SA, Felmlee MA, Morris ME. Brain uptake of the drug of abuse γ-hydroxybutyric acid in rats. Drug Metab Dispos 2011; 40:212-8. [PMID: 22019629 DOI: 10.1124/dmd.111.041749] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
γ-Hydroxybutyric acid (GHB) is an endogenous compound and a substrate for the ubiquitous monocarboxylate transporter (MCT) family. GHB is also a drug of abuse due to its sedative/hypnotic and euphoric effects, with overdoses resulting in toxicity and death. The goal of this study was to characterize the distribution of GHB into the brain using in vivo microdialysis and in vitro uptake studies and to determine concentration-effect relationships for GHB in a rat animal model. GHB was administered to rats (400, 600, and 800 mg/kg i.v.), and blood, dialysate, and urine were collected for 6 h post-GHB administration. The GHB plasma and extracellular fluid (ECF) concentration-time profiles revealed that GHB concentrations in ECF closely followed plasma GHB concentrations. Sleep time increased in a dose-dependent manner (91 ± 18, 134 ± 11, and 168 ± 13 min, for GHB 400, 600, and 800 mg/kg, respectively). GHB partitioning into brain ECF was not significantly different at 400, 600, and 800 mg/kg. GHB uptake in rat and human brain endothelial cells exhibited concentration dependence. The concentration-dependent uptake of GHB at pH 7.4 was best-fit to a single-transporter model [K(m) = 18.1 mM (human), 23.3 mM (rat), V(max) = 248 and 258 pmol · mg(-1) · min(-1) for human and rat, respectively]. These findings indicate that although GHB distribution into the brain is mediated via MCT transporters, it is not capacity-limited over the range of doses studied in this investigation.
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Affiliation(s)
- Samuel A Roiko
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, 527 Hochstetter Hall, Buffalo, NY 14260, USA
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27
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Nasrallah FA, Balcar VJ, Rae CD. Activity-dependent γ-aminobutyric acid release controls brain cortical tissue slice metabolism. J Neurosci Res 2011; 89:1935-45. [DOI: 10.1002/jnr.22649] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/15/2011] [Accepted: 03/01/2011] [Indexed: 12/16/2022]
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