51
|
Hirrlinger J, Nave KA. Adapting brain metabolism to myelination and long-range signal transduction. Glia 2014; 62:1749-61. [DOI: 10.1002/glia.22737] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 07/23/2014] [Accepted: 07/23/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Johannes Hirrlinger
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig; Leipzig Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
| |
Collapse
|
52
|
Plemel JR, Keough MB, Duncan GJ, Sparling JS, Yong VW, Stys PK, Tetzlaff W. Remyelination after spinal cord injury: Is it a target for repair? Prog Neurobiol 2014; 117:54-72. [DOI: 10.1016/j.pneurobio.2014.02.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/15/2014] [Accepted: 02/20/2014] [Indexed: 12/12/2022]
|
53
|
Di Pietro V, Amorini AM, Tavazzi B, Vagnozzi R, Logan A, Lazzarino G, Signoretti S, Lazzarino G, Belli A. The molecular mechanisms affecting N-acetylaspartate homeostasis following experimental graded traumatic brain injury. Mol Med 2014; 20:147-57. [PMID: 24515258 DOI: 10.2119/molmed.2013.00153] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/03/2014] [Indexed: 11/06/2022] Open
Abstract
To characterize the molecular mechanisms of N-acetylaspartate (NAA) metabolism following traumatic brain injury (TBI), we measured the NAA, adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentrations and calculated the ATP/ADP ratio at different times from impact, concomitantly evaluating the gene and protein expressions controlling NAA homeostasis (the NAA synthesizing and degrading enzymes N-acetyltransferase 8-like and aspartoacylase, respectively) in rats receiving either mild or severe TBI. The reversible changes in NAA induced by mild TBI were due to a combination of transient mitochondrial malfunctioning with energy crisis (decrease in ATP and in the ATP/ADP ratio) and modulation in the gene and protein levels of N-acetyltransferase 8-like and increase of aspartoacylase levels. The irreversible decrease in NAA following severe TBI, was instead characterized by profound mitochondrial malfunctioning (constant 65% decrease of the ATP/ADP indicating permanent impairment of the mitochondrial phosphorylating capacity), dramatic repression of the N-acetyltransferase 8-like gene and concomitant remarkable increase in the aspartoacylase gene and protein levels. The mechanisms underlying changes in NAA homeostasis following graded TBI might be of note for possible new therapeutic approaches and will help in understanding the effects of repeat concussions occurring during particular periods of the complex NAA recovery process, coincident with the so called window of brain vulnerability.
Collapse
Affiliation(s)
- Valentina Di Pietro
- Neuropharmacology and Neurobiology Section, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Angela Maria Amorini
- Institute of Biochemistry and Clinical Biochemistry, Catholic University of Rome, Rome, Italy
| | - Barbara Tavazzi
- Institute of Biochemistry and Clinical Biochemistry, Catholic University of Rome, Rome, Italy
| | - Roberto Vagnozzi
- Department of Biomedicine and Prevention, Section of Neurosurgery, University of Rome Tor Vergata, Rome, Italy
| | - Ann Logan
- Neuropharmacology and Neurobiology Section, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Giacomo Lazzarino
- Institute of Biochemistry and Clinical Biochemistry, Catholic University of Rome, Rome, Italy
| | - Stefano Signoretti
- Division of Neurosurgery, Department of Neurosciences Head and Neck Surgery, San Camillo Hospital, Rome, Italy
| | - Giuseppe Lazzarino
- Department of Biology, Geology and Environmental Sciences, Division of Biochemistry and Molecular Biology, University of Catania, Catania, Italy
| | - Antonio Belli
- Neuropharmacology and Neurobiology Section, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| |
Collapse
|
54
|
Hertz L, Rodrigues TB. Astrocytic-Neuronal-Astrocytic Pathway Selection for Formation and Degradation of Glutamate/GABA. Front Endocrinol (Lausanne) 2014; 5:42. [PMID: 24772106 PMCID: PMC3982103 DOI: 10.3389/fendo.2014.00042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/19/2014] [Indexed: 12/16/2022] Open
Affiliation(s)
- Leif Hertz
- College of Basic Medical Sciences, China Medical University, Shenyang, China
- *Correspondence: ;
| | - Tiago B. Rodrigues
- CRUK Cambridge Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK
- *Correspondence: ;
| |
Collapse
|
55
|
Linne ML, Jalonen TO. Astrocyte-neuron interactions: from experimental research-based models to translational medicine. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 123:191-217. [PMID: 24560146 DOI: 10.1016/b978-0-12-397897-4.00005-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this chapter, we review the principal astrocyte functions and the interactions between neurons and astrocytes. We then address how the experimentally observed functions have been verified in computational models and review recent experimental literature on astrocyte-neuron interactions. Benefits of computational neuroscience work are highlighted through selected studies with neurons and astrocytes by analyzing the existing models qualitatively and assessing the relevance of these models to experimental data. Common strategies to mathematical modeling and computer simulation in neuroscience are summarized for the nontechnical reader. The astrocyte-neuron interactions are then further illustrated by examples of some neurological and neurodegenerative diseases, where the miscommunication between glia and neurons is found to be increasingly important.
Collapse
Affiliation(s)
- Marja-Leena Linne
- Computational Neuroscience Group, Department of Signal Processing, Tampere University of Technology, Tampere, Finland
| | - Tuula O Jalonen
- Department of Physiology and Neuroscience, St. George's University, School of Medicine, Grenada, West Indies
| |
Collapse
|
56
|
Moffett JR, Arun P, Ariyannur PS, Namboodiri AMA. N-Acetylaspartate reductions in brain injury: impact on post-injury neuroenergetics, lipid synthesis, and protein acetylation. FRONTIERS IN NEUROENERGETICS 2013; 5:11. [PMID: 24421768 PMCID: PMC3872778 DOI: 10.3389/fnene.2013.00011] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/09/2013] [Indexed: 12/22/2022]
Abstract
N-Acetylaspartate (NAA) is employed as a non-invasive marker for neuronal health using proton magnetic resonance spectroscopy (MRS). This utility is afforded by the fact that NAA is one of the most concentrated brain metabolites and that it produces the largest peak in MRS scans of the healthy human brain. NAA levels in the brain are reduced proportionately to the degree of tissue damage after traumatic brain injury (TBI) and the reductions parallel the reductions in ATP levels. Because NAA is the most concentrated acetylated metabolite in the brain, we have hypothesized that NAA acts in part as an extensive reservoir of acetate for acetyl coenzyme A synthesis. Therefore, the loss of NAA after TBI impairs acetyl coenzyme A dependent functions including energy derivation, lipid synthesis, and protein acetylation reactions in distinct ways in different cell populations. The enzymes involved in synthesizing and metabolizing NAA are predominantly expressed in neurons and oligodendrocytes, respectively, and therefore some proportion of NAA must be transferred between cell types before the acetate can be liberated, converted to acetyl coenzyme A and utilized. Studies have indicated that glucose metabolism in neurons is reduced, but that acetate metabolism in astrocytes is increased following TBI, possibly reflecting an increased role for non-glucose energy sources in response to injury. NAA can provide additional acetate for intercellular metabolite trafficking to maintain acetyl CoA levels after injury. Here we explore changes in NAA, acetate, and acetyl coenzyme A metabolism in response to brain injury.
Collapse
Affiliation(s)
- John R. Moffett
- Neuroscience Program, Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health SciencesBethesda, MD, USA
| | | | | | | |
Collapse
|
57
|
Rinholm JE, Bergersen LH. White matter lactate--does it matter? Neuroscience 2013; 276:109-16. [PMID: 24125892 DOI: 10.1016/j.neuroscience.2013.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/12/2013] [Accepted: 10/02/2013] [Indexed: 10/26/2022]
Abstract
About half of the human brain is white matter, characterized by axons covered in myelin, which facilitates the high speed of nerve signals from one brain area to another. At the time of myelination, the oligodendrocytes that synthesize myelin require a large amount of energy for this task. Conditions that deprive the tissue of energy can kill the oligodendrocytes. During brain development, the oligodendrocytes may use lactate as an alternative source of energy and material for myelin formation. Mature oligodendrocytes, however, can release lactate through the myelin sheath as nutrient for axons. In addition, lactate carries signals as a volume transmitter. Myelin thus seems to serve as a provider of substrates and signals for axons, and not as a mere insulator. We review the fluxes of lactate in white matter and their significance in brain function.
Collapse
Affiliation(s)
- J E Rinholm
- The Brain and Muscle Energy Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, PB1105 Blindern, N-0317 Oslo, Norway; Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - L H Bergersen
- The Brain and Muscle Energy Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, PB1105 Blindern, N-0317 Oslo, Norway; Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Oral Biology, University of Oslo, Norway.
| |
Collapse
|
58
|
Abstract
Although severe stress can elicit toxicity, mild stress often elicits adaptations. Here we review the literature on stress-induced adaptations versus stress sensitization in models of neurodegenerative diseases. We also describe our recent findings that chronic proteotoxic stress can elicit adaptations if the dose is low but that high-dose proteotoxic stress sensitizes cells to subsequent challenges. In these experiments, long-term, low-dose proteasome inhibition elicited protection in a superoxide dismutase-dependent manner. In contrast, acute, high-dose proteotoxic stress sensitized cells to subsequent proteotoxic challenges by eliciting catastrophic loss of glutathione. However, even in the latter model of synergistic toxicity, several defensive proteins were upregulated by severe proteotoxicity. This led us to wonder whether high-dose proteotoxic stress can elicit protection against subsequent challenges in astrocytes, a cell type well known for their resilience. In support of this new hypothesis, we found that the astrocytes that survived severe proteotoxicity became harder to kill. The adaptive mechanism was glutathione dependent. If these findings can be generalized to the human brain, similar endogenous adaptations may help explain why neurodegenerative diseases are so delayed in appearance and so slow to progress. In contrast, sensitization to severe stress may explain why defenses eventually collapse in vulnerable neurons.
Collapse
Affiliation(s)
- Rehana K Leak
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University
| |
Collapse
|