1
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Li S, Wang J, Andersen JV, Aldana BI, Zhang B, Prochownik EV, Rosenberg PA. Misprogramming of glucose metabolism impairs recovery of hippocampal slices from neuronal GLT-1 knockout mice and contributes to excitotoxic injury through mitochondrial superoxide production. J Neurochem 2024. [PMID: 39193789 DOI: 10.1111/jnc.16205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/09/2024] [Accepted: 08/04/2024] [Indexed: 08/29/2024]
Abstract
We have previously reported a failure of recovery of synaptic function in the CA1 region of acute hippocampal slices from mice with a conditional neuronal knockout (KO) of GLT-1 (EAAT2, Slc1A2) driven by synapsin-Cre (synGLT-1 KO). The failure of recovery of synaptic function is due to excitotoxic injury. We hypothesized that changes in mitochondrial metabolism contribute to the heightened vulnerability to excitotoxicity in the synGLT-1 KO mice. We found impaired flux of carbon from 13C-glucose into the tricarboxylic acid cycle in synGLT-1 KO cortical and hippocampal slices compared with wild-type (WT) slices. In addition, we found downregulation of the neuronal glucose transporter GLUT3 in both genotypes. Flux of carbon from [1,2-13C]acetate, thought to be astrocyte-specific, was increased in the synGLT-KO hippocampal slices but not cortical slices. Glycogen stores, predominantly localized to astrocytes, are rapidly depleted in slices after cutting, and are replenished during ex vivo incubation. In the synGLT-1 KO, replenishment of glycogen stores during ex vivo incubation was compromised. These results suggest both neuronal and astrocytic metabolic perturbations in the synGLT-1 KO slices. Supplementing incubation medium during recovery with 20 mM D-glucose normalized glycogen replenishment but had no effect on recovery of synaptic function. In contrast, 20 mM non-metabolizable L-glucose substantially improved recovery of synaptic function, suggesting that D-glucose metabolism contributes to the excitotoxic injury in the synGLT-1 KO slices. L-lactate substitution for D-glucose did not promote recovery of synaptic function, implicating mitochondrial metabolism. Consistent with this hypothesis, phosphorylation of pyruvate dehydrogenase, which decreases enzyme activity, was increased in WT slices during the recovery period, but not in synGLT-1 KO slices. Since metabolism of glucose by the mitochondrial electron transport chain is associated with superoxide production, we tested the effect of drugs that scavenge and prevent superoxide production. The superoxide dismutase/catalase mimic EUK-134 conferred complete protection and full recovery of synaptic function. A site-specific inhibitor of complex III superoxide production, S3QEL-2, was also protective, but inhibitors of NADPH oxidase were not. In summary, we find that the failure of recovery of synaptic function in hippocampal slices from the synGLT-1 KO mouse, previously shown to be due to excitotoxic injury, is caused by production of superoxide by mitochondrial metabolism.
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Affiliation(s)
- S Li
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - J Wang
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - J V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - B I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - B Zhang
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - E V Prochownik
- Division of Hematology/Oncology, UPMC Children's Hospital, Pittsburgh, Pennsylvania, USA
| | - P A Rosenberg
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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2
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Cerina M, Levers M, Keller JM, Frega M. Neuroprotective role of lactate in a human in vitro model of the ischemic penumbra. Sci Rep 2024; 14:7973. [PMID: 38575687 PMCID: PMC10994928 DOI: 10.1038/s41598-024-58669-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 04/02/2024] [Indexed: 04/06/2024] Open
Abstract
In patients suffering from cerebral ischemic stroke, there is an urgent need for treatments to protect stressed yet viable brain cells. Recently, treatment strategies that induce neuronal activity have been shown to be neuroprotective. Here, we hypothesized that neuronal activation might maintain or trigger the astrocyte-to-neuron lactate shuttle (ANLS), whereby lactate is released from astrocytes to support the energy requirements of ATP-starved hypoxic neurons, and this leads to the observed neuroprotection. We tested this by using a human cell based in vitro model of the ischemic penumbra and investigating whether lactate might be neuroprotective in this setting. We found that lactate transporters are involved in the neuroprotective effect mediated by neuronal activation. Furthermore, we showed that lactate exogenously administered before hypoxia correlated with neuroprotection in our cellular model. In addition, stimulation of astrocyte with consequent endogenous production of lactate resulted in neuroprotection. To conclude, here we presented evidence that lactate transport into neurons contributes to neuroprotection during hypoxia providing a potential basis for therapeutic approaches in ischemic stroke.
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Affiliation(s)
- Marta Cerina
- Department of Clinical Neurophysiology, University of Twente, 7522 NB, Enschede, The Netherlands
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, piazza della Scienza 2, 20126, Milan, Italy
| | - Marloes Levers
- Department of Clinical Neurophysiology, University of Twente, 7522 NB, Enschede, The Netherlands
| | - Jason M Keller
- Department of Human Genetics, Radboudumc, Donders Institute for Brain, Cognition, and Behaviour, 6500 HB, Nijmegen, The Netherlands
| | - Monica Frega
- Department of Clinical Neurophysiology, University of Twente, 7522 NB, Enschede, The Netherlands.
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3
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Veeraiah P, Jansen JFA. Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States. Metabolites 2023; 13:metabo13040577. [PMID: 37110235 PMCID: PMC10143499 DOI: 10.3390/metabo13040577] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/06/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
The brain is a highly energetic organ. Although the brain can consume metabolic substrates, such as lactate, glycogen, and ketone bodies, the energy metabolism in a healthy adult brain mainly relies on glucose provided via blood. The cerebral metabolism of glucose produces energy and a wide variety of intermediate metabolites. Since cerebral metabolic alterations have been repeatedly implicated in several brain disorders, understanding changes in metabolite levels and corresponding cell-specific neurotransmitter fluxes through different substrate utilization may highlight the underlying mechanisms that can be exploited to diagnose or treat various brain disorders. Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure tissue metabolism in vivo. 1H-MRS is widely applied in research at clinical field strengths (≤3T) to measure mostly high abundant metabolites. In addition, X-nuclei MRS including, 13C, 2H, 17O, and 31P, are also very promising. Exploiting the higher sensitivity at ultra-high-field (>4T; UHF) strengths enables obtaining unique insights into different aspects of the substrate metabolism towards measuring cell-specific metabolic fluxes in vivo. This review provides an overview about the potential role of multinuclear MRS (1H, 13C, 2H, 17O, and 31P) at UHF to assess the cerebral metabolism and the metabolic insights obtained by applying these techniques in both healthy and diseased states.
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Affiliation(s)
- Pandichelvam Veeraiah
- Scannexus (Ultra-High-Field MRI Center), 6229 EV Maastricht, The Netherlands
- Faculty of Health Medicine and Life Sciences, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
- School for Mental Health and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
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4
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Szrejder M, Typiak M, Pikul P, Audzeyenka I, Rachubik P, Rogacka D, Narajczyk M, Piwkowska A. Role of L-lactate as an energy substrate in primary rat podocytes under physiological and glucose deprivation conditions. Eur J Cell Biol 2023; 102:151298. [PMID: 36805821 DOI: 10.1016/j.ejcb.2023.151298] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023] Open
Abstract
Lactate has long been acknowledged to be a metabolic waste product, but it has more recently been found as a fuel energy source in mammalian cells. Podocytes are an important component of the glomerular filter, and their role in maintaining the structural integrity of this structure was established. These cells rely on a constant energy supply and reservoir. The utilization of alternative energy substrates to preserve energetic homeostasis is a subject of extensive research, and lactate appears to be one such candidate. Therefore, we investigated the role of lactate as an energy substrate and characterize the lactate transport system in cultured rat podocytes during sufficient and insufficient glucose supplies. The present study, for the first time, demonstrated the presence of lactate transporters in podocytes. Moreover, we observed modified the amount of these transporters in response to limited glucose availability and after l-lactate supplementation. Simultaneously, exposure to l-lactate preserved cell survival during insufficient glucose supply. Interestingly, during glucose deprivation, lactate exposure allowed the steady flow of glycolysis and prevented glycogen reserves depletion. Summarizing, podocytes utilize lactate as an energy substrate and possess a developed system that controls lactate homeostasis, suggesting that it plays an essential role in podocyte metabolism, especially during fluctuations of energy availability.
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Affiliation(s)
- Maria Szrejder
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
| | - Marlena Typiak
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdansk, Faculty of Biology, Gdansk, Poland
| | - Piotr Pikul
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
| | - Irena Audzeyenka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdansk, Faculty of Chemistry, Gdańsk, Poland
| | - Patrycja Rachubik
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
| | - Dorota Rogacka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdansk, Faculty of Chemistry, Gdańsk, Poland
| | | | - Agnieszka Piwkowska
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdansk, Faculty of Chemistry, Gdańsk, Poland
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5
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Schurr A. From rags to riches: Lactate ascension as a pivotal metabolite in neuroenergetics. Front Neurosci 2023; 17:1145358. [PMID: 36937681 PMCID: PMC10019773 DOI: 10.3389/fnins.2023.1145358] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 02/13/2023] [Indexed: 03/06/2023] Open
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6
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Sonkodi B. Psoriasis, Is It a Microdamage of Our "Sixth Sense"? A Neurocentric View. Int J Mol Sci 2022; 23:11940. [PMID: 36233237 PMCID: PMC9569707 DOI: 10.3390/ijms231911940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/23/2022] Open
Abstract
Psoriasis is considered a multifactorial and heterogeneous systemic disease with many underlying pathologic mechanisms having been elucidated; however, the pathomechanism is far from entirely known. This opinion article will demonstrate the potential relevance of the somatosensory Piezo2 microinjury-induced quad-phasic non-contact injury model in psoriasis through a multidisciplinary approach. The primary injury is suggested to be on the Piezo2-containing somatosensory afferent terminals in the Merkel cell−neurite complex, with the concomitant impairment of glutamate vesicular release machinery in Merkel cells. Part of the theory is that the Merkel cell−neurite complex contributes to proprioception; hence, to the stretch of the skin. Piezo2 channelopathy could result in the imbalanced control of Piezo1 on keratinocytes in a clustered manner, leading to dysregulated keratinocyte proliferation and differentiation. Furthermore, the author proposes the role of mtHsp70 leakage from damaged mitochondria through somatosensory terminals in the initiation of autoimmune and autoinflammatory processes in psoriasis. The secondary phase is harsher epidermal tissue damage due to the primary impaired proprioception. The third injury phase refers to re-injury and sensitization with the derailment of healing to a state when part of the wound healing is permanently kept alive due to genetical predisposition and environmental risk factors. Finally, the quadric damage phase is associated with the aging process and associated inflammaging. In summary, this opinion piece postulates that the primary microinjury of our “sixth sense”, or the Piezo2 channelopathy of the somatosensory terminals contributing to proprioception, could be the principal gateway to pathology due to the encroachment of our preprogrammed genetic encoding.
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Affiliation(s)
- Balázs Sonkodi
- Department of Health Sciences and Sport Medicine, Hungarian University of Sports Sciences, 1123 Budapest, Hungary
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7
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Lactate Neuroprotection against Transient Ischemic Brain Injury in Mice Appears Independent of HCAR1 Activation. Metabolites 2022; 12:metabo12050465. [PMID: 35629969 PMCID: PMC9145226 DOI: 10.3390/metabo12050465] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 01/25/2023] Open
Abstract
Lactate can protect against damage caused by acute brain injuries both in rodents and in human patients. Besides its role as a metabolic support and alleged preferred neuronal fuel in stressful situations, an additional signaling mechanism mediated by the hydroxycarboxylic acid receptor 1 (HCAR1) was proposed to account for lactate’s beneficial effects. However, the administration of HCAR1 agonists to mice subjected to middle cerebral artery occlusion (MCAO) at reperfusion did not appear to exert any relevant protective effect. To further evaluate the involvement of HCAR1 in the protection against ischemic damage, we looked at the effect of HCAR1 absence. We subjected wild-type and HCAR1 KO mice to transient MCAO followed by treatment with either vehicle or lactate. In the absence of HCAR1, the ischemic damage inflicted by MCAO was less pronounced, with smaller lesions and a better behavioral outcome than in wild-type mice. The lower susceptibility of HCAR1 KO mice to ischemic injury suggests that lactate-mediated protection is not achieved or enhanced by HCAR1 activation, but rather attributable to its metabolic effects or related to other signaling pathways. Additionally, in light of these results, we would disregard HCAR1 activation as an interesting therapeutic strategy for stroke patients.
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8
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Zhang M, Wang Y, Bai Y, Dai L, Guo H. Monocarboxylate Transporter 1 May Benefit Cerebral Ischemia via Facilitating Lactate Transport From Glial Cells to Neurons. Front Neurol 2022; 13:781063. [PMID: 35547368 PMCID: PMC9081727 DOI: 10.3389/fneur.2022.781063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Monocarboxylate transporter 1 (MCT1) is expressed in glial cells and some populations of neurons. MCT1 facilitates astrocytes or oligodendrocytes (OLs) in the energy supplement of neurons, which is crucial for maintaining the neuronal activity and axonal function. It is suggested that MCT1 upregulation in cerebral ischemia is protective to ischemia/reperfusion (I/R) injury. Otherwise, its underlying mechanism has not been clearly discussed. In this review, it provides a novel insight that MCT1 may protect brain from I/R injury via facilitating lactate transport from glial cells (such as, astrocytes and OLs) to neurons. It extensively discusses (1) the structure and localization of MCT1; (2) the regulation of MCT1 in lactate transport among astrocytes, OLs, and neurons; and (3) the regulation of MCT1 in the cellular response of lactate accumulation under ischemic attack. At last, this review concludes that MCT1, in cerebral ischemia, may improve lactate transport from glial cells to neurons, which subsequently alleviates cellular damage induced by lactate accumulation (mostly in glial cells), and meets the energy metabolism of neurons.
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Affiliation(s)
- Mao Zhang
- Department of Medical Genetics, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yanyan Wang
- Department of Medical Genetics, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yun Bai
- Department of Medical Genetics, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Limeng Dai
- Department of Medical Genetics, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Hong Guo
- Department of Medical Genetics, College of Basic Medical Sciences, Army Medical University, Chongqing, China
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9
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Brain Metabolic Alterations in Alzheimer's Disease. Int J Mol Sci 2022; 23:ijms23073785. [PMID: 35409145 PMCID: PMC8998942 DOI: 10.3390/ijms23073785] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/23/2022] [Accepted: 03/28/2022] [Indexed: 01/27/2023] Open
Abstract
The brain is one of the most energy-consuming organs in the body. Satisfying such energy demand requires compartmentalized, cell-specific metabolic processes, known to be complementary and intimately coupled. Thus, the brain relies on thoroughly orchestrated energy-obtaining agents, processes and molecular features, such as the neurovascular unit, the astrocyte-neuron metabolic coupling, and the cellular distribution of energy substrate transporters. Importantly, early features of the aging process are determined by the progressive perturbation of certain processes responsible for adequate brain energy supply, resulting in brain hypometabolism. These age-related brain energy alterations are further worsened during the prodromal stages of neurodegenerative diseases, namely Alzheimer's disease (AD), preceding the onset of clinical symptoms, and are anatomically and functionally associated with the loss of cognitive abilities. Here, we focus on concrete neuroenergetic features such as the brain's fueling by glucose and lactate, the transporters and vascular system guaranteeing its supply, and the metabolic interactions between astrocytes and neurons, and on its neurodegenerative-related disruption. We sought to review the principles underlying the metabolic dimension of healthy and AD brains, and suggest that the integration of these concepts in the preventive, diagnostic and treatment strategies for AD is key to improving the precision of these interventions.
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10
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Passarella S, Schurr A, Portincasa P. Mitochondrial Transport in Glycolysis and Gluconeogenesis: Achievements and Perspectives. Int J Mol Sci 2021; 22:ijms222312620. [PMID: 34884425 PMCID: PMC8657705 DOI: 10.3390/ijms222312620] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 01/22/2023] Open
Abstract
Some metabolic pathways involve two different cell components, for instance, cytosol and mitochondria, with metabolites traffic occurring from cytosol to mitochondria and vice versa, as seen in both glycolysis and gluconeogenesis. However, the knowledge on the role of mitochondrial transport within these two glucose metabolic pathways remains poorly understood, due to controversial information available in published literature. In what follows, we discuss achievements, knowledge gaps, and perspectives on the role of mitochondrial transport in glycolysis and gluconeogenesis. We firstly describe the experimental approaches for quick and easy investigation of mitochondrial transport, with respect to cell metabolic diversity. In addition, we depict the mitochondrial shuttles by which NADH formed in glycolysis is oxidized, the mitochondrial transport of phosphoenolpyruvate in the light of the occurrence of the mitochondrial pyruvate kinase, and the mitochondrial transport and metabolism of L-lactate due to the L-lactate translocators and to the mitochondrial L-lactate dehydrogenase located in the inner mitochondrial compartment.
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Affiliation(s)
- Salvatore Passarella
- Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy
- Correspondence: ; Tel.: +39-3293606374
| | - Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville, Louisville, KY 40202, USA;
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy;
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11
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Montana V, Flint D, Waagepetersen HS, Schousboe A, Parpura V. Two Metabolic Fuels, Glucose and Lactate, Differentially Modulate Exocytotic Glutamate Release from Cultured Astrocytes. Neurochem Res 2021; 46:2551-2579. [PMID: 34057673 PMCID: PMC9015689 DOI: 10.1007/s11064-021-03340-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/26/2022]
Abstract
Astrocytes have a prominent role in metabolic homeostasis of the brain and can signal to adjacent neurons by releasing glutamate via a process of regulated exocytosis. Astrocytes synthesize glutamate de novo owing to the pyruvate entry to the citric/tricarboxylic acid cycle via pyruvate carboxylase, an astrocyte specific enzyme. Pyruvate can be sourced from two metabolic fuels, glucose and lactate. Thus, we investigated the role of these energy/carbon sources in exocytotic glutamate release from astrocytes. Purified astrocyte cultures were acutely incubated (1 h) in glucose and/or lactate-containing media. Astrocytes were mechanically stimulated, a procedure known to increase intracellular Ca2+ levels and cause exocytotic glutamate release, the dynamics of which were monitored using single cell fluorescence microscopy. Our data indicate that glucose, either taken-up from the extracellular space or mobilized from the intracellular glycogen storage, sustained glutamate release, while the availability of lactate significantly reduced the release of glutamate from astrocytes. Based on further pharmacological manipulation during imaging along with tandem mass spectrometry (proteomics) analysis, lactate alone, but not in the hybrid fuel, caused metabolic changes consistent with an increased synthesis of fatty acids. Proteomics analysis further unveiled complex changes in protein profiles, which were condition-dependent and generally included changes in levels of cytoskeletal proteins, proteins of secretory organelle/vesicle traffic and recycling at the plasma membrane in aglycemic, lactate or hybrid-fueled astrocytes. These findings support the notion that the availability of energy sources and metabolic milieu play a significant role in gliotransmission.
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Affiliation(s)
- Vedrana Montana
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - Daniel Flint
- Luxumbra Strategic Research, LLC, Arlington, VA, USA
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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12
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Dong S, Qian L, Cheng Z, Chen C, Wang K, Hu S, Zhang X, Wu T. Lactate and Myocadiac Energy Metabolism. Front Physiol 2021; 12:715081. [PMID: 34483967 PMCID: PMC8415870 DOI: 10.3389/fphys.2021.715081] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/29/2021] [Indexed: 12/05/2022] Open
Abstract
The myocardium is capable of utilizing different energy substrates, which is referred to as “metabolic flexibility.” This process assures ATP production from fatty acids, glucose, lactate, amino acids, and ketones, in the face of varying metabolic contexts. In the normal physiological state, the oxidation of fatty acids contributes to approximately 60% of energy required, and the oxidation of other substrates provides the rest. The accumulation of lactate in ischemic and hypoxic tissues has traditionally be considered as a by-product, and of little utility. However, recent evidence suggests that lactate may represent an important fuel for the myocardium during exercise or myocadiac stress. This new paradigm drives increasing interest in understanding its role in cardiac metabolism under both physiological and pathological conditions. In recent years, blood lactate has been regarded as a signal of stress in cardiac disease, linking to prognosis in patients with myocardial ischemia or heart failure. In this review, we discuss the importance of lactate as an energy source and its relevance to the progression and management of heart diseases.
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Affiliation(s)
- Shuohui Dong
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Linhui Qian
- Department of Colorectal and Anal Surgery, Feicheng Hospital Affiliated to Shandong First Medical University, Feicheng, China
| | - Zhiqiang Cheng
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Chang Chen
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Kexin Wang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Sanyuan Hu
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Xiang Zhang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, SA, Australia.,Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, SA, Australia
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13
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Buscemi L, Blochet C, Magistretti PJ, Hirt L. Hydroxycarboxylic Acid Receptor 1 and Neuroprotection in a Mouse Model of Cerebral Ischemia-Reperfusion. Front Physiol 2021; 12:689239. [PMID: 34093243 PMCID: PMC8176103 DOI: 10.3389/fphys.2021.689239] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/27/2021] [Indexed: 11/13/2022] Open
Abstract
Lactate is an intriguing molecule with emerging physiological roles in the brain. It has beneficial effects in animal models of acute brain injuries and traumatic brain injury or subarachnoid hemorrhage patients. However, the mechanism by which lactate provides protection is unclear. While there is evidence of a metabolic effect of lactate providing energy to deprived neurons, it can also activate the hydroxycarboxylic acid receptor 1 (HCAR1), a Gi-coupled protein receptor that modulates neuronal firing rates. After cerebral hypoxia-ischemia, endogenously produced brain lactate is largely increased, and the exogenous administration of more lactate can decrease lesion size and ameliorate the neurological outcome. To test whether HCAR1 plays a role in lactate-induced neuroprotection, we injected the agonists 3-chloro-5-hydroxybenzoic acid and 3,5-dihydroxybenzoic acid into mice subjected to 30-min middle cerebral artery occlusion. The in vivo administration of HCAR1 agonists at reperfusion did not appear to exert any relevant protective effect as seen with lactate administration. Our results suggest that the protective effects of lactate after hypoxia-ischemia come rather from the metabolic effects of lactate than its signaling through HCAR1.
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Affiliation(s)
- Lara Buscemi
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Camille Blochet
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Pierre J Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Lorenz Hirt
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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Zhang T, Zheng H, Fan K, Xia N, Li J, Yang C, Gao H, Yang Y. NMR-based metabolomics characterizes metabolic changes in different brain regions of streptozotocin-induced diabetic mice with cognitive decline. Metab Brain Dis 2020; 35:1165-1173. [PMID: 32643092 DOI: 10.1007/s11011-020-00598-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 07/01/2020] [Indexed: 02/06/2023]
Abstract
Diabetes at advanced age increases rise of cognitive impairment, but its potential mechanisms are still far from being fully understood. In this study, we analyzed the metabolic alterations in six different brain regions between streptozotocin (STZ)-induced diabetic mice with cognitive decline (DM) and age-matched controls (CON) using a 1H NMR-based metabolomics approach, to explore potential metabolic mechanisms underlying diabetes-induced cognitive decline. The results show that DM mice had a peculiar metabolic phenotype in all brain regions, mainly involving increased lactate level, decreased choline and energy metabolism as well as disrupted astrocyte-neuron metabolism. Furthermore, these metabolic changes exhibited a brain region-specific pattern. Collectively, our results suggest that brain region-specific metabolic disorders may be responsible for diabetes-induced cognitive dysfunction.
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Affiliation(s)
- Tingting Zhang
- Department of Radiology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Hong Zheng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, 325035, China
| | - Kai Fan
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, 325035, China
| | - Nengzhi Xia
- Department of Radiology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Jiance Li
- Department of Radiology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Changwei Yang
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, 325035, China
| | - Hongchang Gao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, 325035, China.
| | - Yunjun Yang
- Department of Radiology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China.
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15
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Zhao L, Cui C, Liu Q, Sun J, He K, Adam AA, Luo J, Li Z, Wang Y, Yang S. Combined exposure to hypoxia and ammonia aggravated biological effects on glucose metabolism, oxidative stress, inflammation and apoptosis in largemouth bass (Micropterus salmoides). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 224:105514. [PMID: 32502847 DOI: 10.1016/j.aquatox.2020.105514] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 04/29/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Hypoxia and ammonia are unavoidable environmental factors in aquaculture, and have been shown cause various adverse effects in fish. In the present study, a two-factor crossover experiment was carried out to evaluate the combined effect of hypoxia and ammonia on oxidative stress and glucose metabolism endpoints in largemouth bass. The fish were divided into four experimental groups: hypoxia and ammonia group, hypoxia group, ammonia group, and control group. The results showed that hypoxia and ammonia exposures both induced antioxidant response and oxidative stress (superoxide dismutase [SOD] and catalase [CAT] activities increased first then decreased, and malondialdehyde accumulated) and anaerobic glycolysis (increase of blood glucose, decrease of liver glycogen, accumulation of lactate, and increased lactate dehydrogenase activity). In addition, hypoxia and ammonia upregulated antioxidant enzyme genes (Cu/ZnSOD, CAT, and GPx), apoptosis genes (caspase 3, caspase 8, and caspase 9), as well as inflammatory genes (interleukin [IL]-1β and IL-8) and downregulated an anti-inflammatory gene (IL-10), suggesting that apoptosis and inflammation may be related to oxidative stress. The increased expression of GLUT1, LDH, and MCT4 were induced by hypoxia and ammonia, suggesting that anaerobic glycolysis was increased. Furthermore, fish suffering from hypoxia or ammonia exposure showed some changes in gill tissues histology, and the most severe lesions of gill tissues appeared in simultaneous exposure. Overall, both hypoxia and ammonia affected homeostasis, and simultaneous exposure led to more deleterious effects on largemouth bass than exposure to the individual stressors.
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Affiliation(s)
- Liulan Zhao
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Can Cui
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Qiao Liu
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Junlong Sun
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Kuo He
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Ahmed Abdi Adam
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Jie Luo
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Zhiqiong Li
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Yan Wang
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
| | - Song Yang
- College of Animal Science and Technology, Sichuan Agricultural University (SICAU), Chengdu, Sichuan 611130, China.
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Buscemi L, Blochet C, Price M, Magistretti PJ, Lei H, Hirt L. Extended preclinical investigation of lactate for neuroprotection after ischemic stroke. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2020. [DOI: 10.1177/2514183x20904571] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Lactate has been shown to have beneficial effect both in experimental ischemia–reperfusion models and in human acute brain injury patients. To further investigate lactate’s neuroprotective action in experimental in vivo ischemic stroke models prior to its use in clinics, we tested (1) the outcome of lactate administration on permanent ischemia and (2) its compatibility with the only currently approved drug for the treatment of acute ischemic stroke, recombinant tissue plasminogen activator (rtPA), after ischemia–reperfusion. We intravenously injected mice with 1 µmol/g sodium l-lactate 1 h or 3 h after permanent middle cerebral artery occlusion (MCAO) and looked at its effect 24 h later. We show a beneficial effect of lactate when administered 1 h after ischemia onset, reducing the lesion size and improving neurological outcome. The weaker effect observed at 3 h could be due to differences in the metabolic profiles related to damage progression. Next, we administered 0.9 mg/kg of intravenous (iv) rtPA, followed by intracerebroventricular injection of 2 µL of 100 mmol/L sodium l-lactate to treat mice subjected to 35-min transient MCAO and compared the outcome (lesion size and behavior) of the combined treatment with that of single treatments. The administration of lactate after rtPA has positive influence on the functional outcome and attenuates the deleterious effects of rtPA, although not as strongly as lactate administered alone. The present work gives a lead for patient selection in future clinical studies of treatment with inexpensive and commonly available lactate in acute ischemic stroke, namely patients not treated with rtPA but mechanical thrombectomy alone or patients without recanalization therapy.
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Affiliation(s)
- Lara Buscemi
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital Centre and University of Lausanne, Lausanne, Switzerland
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Camille Blochet
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital Centre and University of Lausanne, Lausanne, Switzerland
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Melanie Price
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital Centre and University of Lausanne, Lausanne, Switzerland
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Pierre J Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
- Department of Psychiatry, Lausanne University Hospital Centre and University of Lausanne, Lausanne, Switzerland
| | - Hongxia Lei
- Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Lorenz Hirt
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital Centre and University of Lausanne, Lausanne, Switzerland
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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Gul Z, Buyukuysal MC, Buyukuysal RL. Brain slice viability determined under normoxic and oxidative stress conditions: involvement of slice quantity in the medium. Neurol Res 2020; 42:228-238. [DOI: 10.1080/01616412.2020.1723299] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Zulfiye Gul
- Department of Medical Pharmacology, Faculty of Medicine, Bahcesehir University, Istanbul, Turkey
| | - M. Cagatay Buyukuysal
- Department of Biostatistics, School of Medicine, Bulent Ecevit University, Zonguldak, Turkey
| | - R. Levent Buyukuysal
- Department of Medical Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey
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Lactate-Mediated Protection of Retinal Ganglion Cells. J Mol Biol 2019; 431:1878-1888. [PMID: 30878479 DOI: 10.1016/j.jmb.2019.03.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 02/27/2019] [Accepted: 03/05/2019] [Indexed: 12/30/2022]
Abstract
Loss of retinal ganglion cells (RGCs) is a leading cause of blinding conditions. The purpose of this study was to evaluate the effect of extracellular l-lactate on RGC survival facilitated through lactate metabolism and ATP production. We identified lactate as a preferred energy substrate over glucose in murine RGCs and showed that lactate metabolism and consequently increased ATP production are crucial components in promoting RGC survival during energetic crisis. Lactate was released to the extracellular environment in the presence of glucose and detained intracellularly during glucose deprivation. Lactate uptake and metabolism was unaltered in the presence and absence of glucose. However, the ATP production declined significantly for 24 h of glucose deprivation and increased significantly in the presence of lactate. Finally, lactate exposure for 2 and 24 h resulted in increased RGC survival during glucose deprivation. In conclusion, the metabolic pathway of lactate in RGCs may be of great future interest to unravel potential pharmaceutical targets, ultimately leading to novel therapies in the prevention of blinding neurodegenerative diseases, for example, glaucoma.
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Oses JP, Müller AP, Strogulski NR, Moreira JD, Böhmer AE, Hansel G, Carteri RB, Busnello JV, Kopczynski A, Rodolphi MS, Souza DO, Portela LV. Sustained elevation of cerebrospinal fluid glucose and lactate after a single seizure does not parallel with mitochondria energy production. Epilepsy Res 2019; 152:35-41. [PMID: 30875635 DOI: 10.1016/j.eplepsyres.2019.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/18/2019] [Accepted: 03/09/2019] [Indexed: 12/22/2022]
Abstract
Generalized seizures trigger excessive neuronal firing that imposes large demands on the brain glucose/lactate availability and utilization, which synchronization requires an integral mitochondrial oxidative capability. We investigated whether a single convulsive crisis affects brain glucose/lactate availability and mitochondrial energy production. Adult male Wistar rats received a single injection of pentylentetrazol (PTZ, 60 mg/kg, i.p.) or saline. The cerebrospinal fluid (CSF) levels of glucose and lactate, mitochondrial respirometry, [14C]-2-deoxy-D-glucose uptake, glycogen content and cell viability in hippocampus were measured. CSF levels of glucose and lactate (mean ± SD) in control animals were 68.08 ± 11.62 mg/dL and 1.17 ± 0.32 mmol/L, respectively. Tonic-clonic seizures increased glucose levels at 10 min (96.25 ± 13.19) peaking at 60 min (113.03 ± 16.34) returning to control levels at 24 h (50.12 ± 12.81), while lactate increased at 10 min (3.23 ± 1.57) but returned to control levels at 360 min after seizures (1.58 ± 0.21). The hippocampal [14C]-2-deoxy-D-glucose uptake, glycogen content, and cell viability decreased up to 60 min after the seizures onset. Also, an uncoupling between mitochondrial oxygen consumption and ATP synthesis via FoF1-ATP synthase was observed at 10 min, 60 min and 24 h after seizures. In summary, after a convulsive seizure glucose and lactate levels immediately rise within the brain, however, considering the acute impact of this metabolic crisis, mitochondria are not able to increase energy production thereby affecting cell viability.
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Affiliation(s)
- Jean Pierre Oses
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Alexandre Pastoris Müller
- Unidade de Ciências da Saúde, Laboratório de Bioquímica e Fisiologia do Exercício Universidade do Extremo Sul Catarinense-UNESC, Av. Universitária, 1105 - Bairro Universitário, CEP 88806-000, Criciúma, Santa Catarina, Brazil
| | - Nathan Ryzewski Strogulski
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Julia D Moreira
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Departamento de Nutrição, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Ana Elisa Böhmer
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Gisele Hansel
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Randhall Bruce Carteri
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - João Vicente Busnello
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA
| | - Afonso Kopczynski
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marcelo Salimen Rodolphi
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Diogo Onofre Souza
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Luis Valmor Portela
- Programa de Pós-graduação em Ciências Biológicas, Bioquímica, Laboratório de Neurotrauma e Biomarcadores, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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20
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Effects of Hypertonic Saline and Sodium Lactate on Cortical Cerebral Microcirculation and Brain Tissue Oxygenation. J Neurosurg Anesthesiol 2018; 30:163-170. [PMID: 28338505 DOI: 10.1097/ana.0000000000000427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Hyperosmolar solutions have been used in neurosurgery to modify brain bulk. The aim of this animal study was to compare the short-term effects of equivolemic, equiosmolar solutions of hypertonic saline (HTS) and sodium lactate (HTL) on cerebral cortical microcirculation and brain tissue oxygenation in a rabbit craniotomy model. METHODS Rabbits (weight, 1.5 to 2.0 kg) were anesthetized, ventilated mechanically, and subjected to a craniotomy. The animals were allocated randomly to receive a 3.75 mL/kg intravenous infusion of either 3.2% HTS (group HTS, n=9), half-molar sodium lactate (group HTL, n=10), or normal saline (group C, n=9). Brain tissue partial pressure of oxygen (PbtO2) and microcirculation in the cerebral cortex using sidestream dark-field imaging were evaluated before, 20 and 40 minutes after 15 minutes of hyperosmolar solution infusion. Global hemodynamic data were recorded, and blood samples for laboratory analysis were obtained at the time of sidestream dark-field image recording. RESULTS No differences in the microcirculatory parameters were observed between the groups before and after the use of osmotherapy. Brain tissue oxygen deteriorated over time in groups C and HTL, this deterioration was not significant in the group HTS. CONCLUSIONS Our findings suggest that equivolemic, equiosmolar HTS and HTL solutions equally preserve perfusion of cortical brain microcirculation in a rabbit craniotomy model. The use of HTS was better in preventing the worsening of brain tissue oxygen tension.
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21
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Rimmele TS, de Castro Abrantes H, Wellbourne-Wood J, Lengacher S, Chatton JY. Extracellular Potassium and Glutamate Interact To Modulate Mitochondria in Astrocytes. ACS Chem Neurosci 2018; 9:2009-2015. [PMID: 29741354 DOI: 10.1021/acschemneuro.8b00124] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Astrocytes clear glutamate and potassium, both of which are released into the extracellular space during neuronal activity. These processes are intimately linked with energy metabolism. Whereas astrocyte glutamate uptake causes cytosolic and mitochondrial acidification, extracellular potassium induces bicarbonate-dependent cellular alkalinization. This study aimed at quantifying the combined impact of glutamate and extracellular potassium on mitochondrial parameters of primary cultured astrocytes. Glutamate in 3 mM potassium caused a stronger acidification of mitochondria compared to cytosol. 15 mM potassium caused alkalinization that was stronger in the cytosol than in mitochondria. While the combined application of 15 mM potassium and glutamate led to a marked cytosolic alkalinization, pH only marginally increased in mitochondria. Thus, potassium and glutamate effects cannot be arithmetically summed, which also applies to their effects on mitochondrial potential and respiration. The data implies that, because of the nonlinear interaction between the effects of potassium and glutamate, astrocytic energy metabolism will be differentially regulated.
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Affiliation(s)
- Theresa S. Rimmele
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | | | - Joel Wellbourne-Wood
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | | | - Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
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22
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Wang B, Liu S, Fan B, Xu X, Chen Y, Lu R, Xu Z, Liu X. PKM2 is involved in neuropathic pain by regulating ERK and STAT3 activation in rat spinal cord. J Headache Pain 2018; 19:7. [PMID: 29349661 PMCID: PMC5773456 DOI: 10.1186/s10194-018-0836-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 01/08/2018] [Indexed: 01/10/2023] Open
Abstract
Background Pyruvate kinase isozymes M2 (PKM2), as a member of pyruvate kinase family, plays a role of glycolytic enzyme in glucose metabolism. It also functions as protein kinase in cell proliferation, signaling, immunity, and gene transcription. In this study, the role of PKM2 in neuropathic pain induced by chronic constriction injury (CCI) was investigated. Methods Rats were randomly grouped to establish CCI models. PKM2, extracellular regulated protein kinases (EKR), p-ERK, signal transducers and activators of transcription (STAT3), p-STAT3, phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and p-PI3K/AKT proteins expression in spinal cord was examined by Western blot analysis. Cellular location of PKM2 was examined by immunofluorescence. Knockdown of PKM2 was achieved by intrathecal injection of specific small interfering RNA (siRNA). Von Frey filaments and radiant heat tests were performed to determine mechanical allodynia and thermal hyperalgesia respectively. Lactate and adenosine triphosphate (ATP) contents were measured by specific kits. Tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) levels were detected by ELISA kits. Results CCI markedly increased PKM2 level in rat spinal cord. Double immunofluorescent staining showed that PKM2 co-localized with neuron, astrocyte, and microglia. Intrathecal injection of PKM2 siRNA not only attenuated CCI-induced ERK and STAT3 activation, but also attenuated mechanical allodynia and thermal hyperalgesia induced by CCI. However, PKM2 siRNA failed to inhibit the activation of AKT. In addition, PKM2 siRNA significantly suppressed the production of lactate and pro-inflammatory mediators. Conclusion Our findings demonstrate that inhibiting PKM2 expression effectively attenuates CCI-induced neuropathic pain and inflammatory responses in rats, possibly through regulating ERK and STAT3 signaling pathway.
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Affiliation(s)
- Binbin Wang
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226001, China
| | - Siyuan Liu
- Department of Anesthesiology, Nantong Maternity and Child Health Hospital, Nantong, Jiangsu, 226018, China
| | - Bingbing Fan
- Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Medical Imaging, Department of Medical Imaging, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Xingguo Xu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226001, China
| | - Yonglin Chen
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226001, China
| | - Rongxiang Lu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226001, China
| | - Zhongling Xu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226001, China.
| | - Xiaojuan Liu
- Department of Pathogen Biology, Medical College, Nantong University, Nantong, Jiangsu, 2266001, China.
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23
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Ferguson BS, Rogatzki MJ, Goodwin ML, Kane DA, Rightmire Z, Gladden LB. Lactate metabolism: historical context, prior misinterpretations, and current understanding. Eur J Appl Physiol 2018; 118:691-728. [PMID: 29322250 DOI: 10.1007/s00421-017-3795-6] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Lactate (La-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La- in metabolism begin. The evidence for La- as a major player in the coordination of whole-body metabolism has since grown rapidly. La- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La-'s central role in metabolism and amplifies our understanding of past research.
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Affiliation(s)
- Brian S Ferguson
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew J Rogatzki
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA
| | - Matthew L Goodwin
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.,Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, Canada
| | - Zachary Rightmire
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA.
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Alnemari AM, Krafcik BM, Mansour TR, Gaudin D. A Comparison of Pharmacologic Therapeutic Agents Used for the Reduction of Intracranial Pressure After Traumatic Brain Injury. World Neurosurg 2017; 106:509-528. [PMID: 28712906 DOI: 10.1016/j.wneu.2017.07.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/01/2017] [Accepted: 07/05/2017] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In neurotrauma care, a better understanding of treatments after traumatic brain injury (TBI) has led to a significant decrease in morbidity and mortality in this population. TBI represents a significant medical problem, and complications after TBI are associated with the initial injury and postevent intracranial processes such as increased intracranial pressure and brain edema. Consequently, appropriate therapeutic interventions are required to reduce brain tissue damage and improve cerebral perfusion. We present a contemporary review of literature on the use of pharmacologic therapies to reduce intracranial pressure after TBI and a comparison of their efficacy. METHODS This review was conducted by PubMed query. Only studies discussing pharmacologic management of patients after TBI were included. This review includes prospective and retrospective studies and includes randomized controlled trials as well as cohort, case-control, observational, and database studies. Systematic literature reviews, meta-analyses, and studies that considered conditions other than TBI or pediatric populations were not included. RESULTS Review of the literature describing the current pharmacologic treatment for intracranial hypertension after TBI most often discussed the use of hyperosmolar agents such as hypertonic saline and mannitol, sedatives such as fentanyl and propofol, benzodiazepines, and barbiturates. Hypertonic saline is associated with faster resolution of intracranial hypertension and restoration of optimal cerebral hemodynamics, although these advantages did not translate into long-term benefits in morbidity or mortality. In patients refractory to treatment with hyperosmolar therapy, induction of a barbiturate coma can reduce intracranial pressure, although requires close monitoring to prevent adverse events. CONCLUSIONS Current research suggests that the use of hypertonic saline after TBI is the best option for immediate decrease in intracranial pressure. A better understanding of the efficacy of each treatment option can help to direct treatment algorithms during the critical early hours of trauma care and continue to improve morbidity and mortality after TBI.
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Affiliation(s)
- Ahmed M Alnemari
- Division of Neurological Surgery, Department of Surgery, University of Toledo Medical Center, Toledo, Ohio, USA
| | - Brianna M Krafcik
- Division of Neurological Surgery, Department of Surgery, University of Toledo Medical Center, Toledo, Ohio, USA
| | - Tarek R Mansour
- Division of Neurological Surgery, Department of Surgery, University of Toledo Medical Center, Toledo, Ohio, USA
| | - Daniel Gaudin
- Division of Neurological Surgery, Department of Surgery, University of Toledo Medical Center, Toledo, Ohio, USA.
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Hadjihambi A, De Chiara F, Hosford PS, Habtetion A, Karagiannis A, Davies N, Gourine AV, Jalan R. Ammonia mediates cortical hemichannel dysfunction in rodent models of chronic liver disease. Hepatology 2017; 65:1306-1318. [PMID: 28066916 PMCID: PMC5396295 DOI: 10.1002/hep.29031] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/22/2016] [Accepted: 12/23/2016] [Indexed: 12/19/2022]
Abstract
UNLABELLED The pathogenesis of hepatic encephalopathy (HE) in cirrhosis is multifactorial and ammonia is thought to play a key role. Astroglial dysfunction is known to be present in HE. Astrocytes are extensively connected by gap junctions formed of connexins, which also exist as functional hemichannels allowing exchange of molecules between the cytoplasm and the extracellular milieu. The astrocyte-neuron lactate shuttle hypothesis suggests that neuronal activity is fueled (at least in part) by lactate provided by neighboring astrocytes. We hypothesized that in HE, astroglial dysfunction could impair metabolic communication between astrocytes and neurons. In this study, we determined whether hyperammonemia leads to hemichannel dysfunction and impairs lactate transport in the cerebral cortex using rat models of HE (bile duct ligation [BDL] and induced hyperammonemia) and also evaluated the effect of ammonia-lowering treatment (ornithine phenylacetate [OP]). Plasma ammonia concentration in BDL rats was significantly reduced by OP treatment. Biosensor recordings demonstrated that HE is associated with a significant reduction in both tonic and hypoxia-induced lactate release in the cerebral cortex, which was normalized by OP treatment. Cortical dye loading experiments revealed hemichannel dysfunction in HE with improvement following OP treatment, while the expression of key connexins was unaffected. CONCLUSION The results of the present study demonstrate that HE is associated with central nervous system hemichannel dysfunction, with ammonia playing a key role. The data provide evidence of a potential neuronal energy deficit due to impaired hemichannel-mediated lactate transport between astrocytes and neurons as a possible mechanism underlying pathogenesis of HE. (Hepatology 2017;65:1306-1318).
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Affiliation(s)
- Anna Hadjihambi
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom,Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Francesco De Chiara
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | - Patrick S. Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Abeba Habtetion
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | | | - Nathan Davies
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | - Alexander V. Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Rajiv Jalan
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
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Bak LK, Schousboe A. Misconceptions regarding basic thermodynamics and enzyme kinetics have led to erroneous conclusions regarding the metabolic importance of lactate dehydrogenase isoenzyme expression. J Neurosci Res 2017; 95:2098-2102. [DOI: 10.1002/jnr.23994] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 01/30/2023]
Affiliation(s)
- Lasse K. Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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Mason S. Lactate Shuttles in Neuroenergetics-Homeostasis, Allostasis and Beyond. Front Neurosci 2017; 11:43. [PMID: 28210209 PMCID: PMC5288365 DOI: 10.3389/fnins.2017.00043] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/20/2017] [Indexed: 12/19/2022] Open
Abstract
Understanding brain energy metabolism—neuroenergetics—is becoming increasingly important as it can be identified repeatedly as the source of neurological perturbations. Within the scientific community we are seeing a shift in paradigms from the traditional neurocentric view to that of a more dynamic, integrated one where astrocytes are no longer considered as being just supportive, and activated microglia have a profound influence. Lactate is emerging as the “good guy,” contrasting its classical “bad guy” position in the now superseded medical literature. This review begins with the evolution of the concept of “lactate shuttles”; goes on to the recent shift in ideas regarding normal neuroenergetics (homeostasis)—specifically, the astrocyte–neuron lactate shuttle; and progresses to covering the metabolic implications whereby homeostasis is lost—a state of allostasis, and the function of microglia. The role of lactate, as a substrate and shuttle, is reviewed in light of allostatic stress, and beyond—in an acute state of allostatic stress in terms of physical brain trauma, and reflected upon with respect to persistent stress as allostatic overload—neurodegenerative diseases. Finally, the recently proposed astrocyte–microglia lactate shuttle is discussed in terms of chronic neuroinflammatory infectious diseases, using tuberculous meningitis as an example. The novelty extended by this review is that the directionality of lactate, as shuttles in the brain, in neuropathophysiological states is emerging as crucial in neuroenergetics.
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Affiliation(s)
- Shayne Mason
- Centre for Human Metabolomics, North-West University Potchefstroom, South Africa
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Ichihara Y, Doi T, Ryu Y, Nagao M, Sawada Y, Ogata T. Oligodendrocyte Progenitor Cells Directly Utilize Lactate for Promoting Cell Cycling and Differentiation. J Cell Physiol 2016; 232:986-995. [PMID: 27861886 PMCID: PMC5299506 DOI: 10.1002/jcp.25690] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 11/11/2016] [Indexed: 12/17/2022]
Abstract
Oligodendrocyte progenitor cells (OPCs) undergo marked morphological changes to become mature oligodendrocytes, but the metabolic resources for this process have not been fully elucidated. Although lactate, a metabolic derivative of glycogen, has been reported to be consumed in oligodendrocytes as a metabolite, and to ameliorate hypomyelination induced by low glucose conditions, it is not clear about the direct contribution of lactate to cell cycling and differentiation of OPCs, and the source of lactate for remyelination. Therefore, we evaluated the effect of 1,4‐dideoxy‐1,4‐imino‐d‐arabinitol (DAB), an inhibitor of the glycogen catabolic enzyme glycogen phosphorylase, in a mouse cuprizone model. Cuprizone induced demyelination in the corpus callosum and remyelination occurred after cuprizone treatment ceased. This remyelination was inhibited by the administration of DAB. To further examine whether lactate affects proliferation or differentiation of OPCs, we cultured mouse primary OPC‐rich cells and analyzed the effect of lactate. Lactate rescued the slowed cell cycling induced by 0.4 mM glucose, as assessed by the BrdU‐positive cell ratio. Lactate also promoted OPC differentiation detected by monitoring the mature oligodendrocyte marker myelin basic protein, in the presence of both 36.6 mM and 0.4 mM glucose. Furthermore, these lactate‐mediated effects were suppressed by the reported monocarboxylate transporter inhibitor, α‐cyano‐4‐hydroxy‐cinnamate. These results suggest that lactate directly promotes the cell cycling rate and differentiation of OPCs, and that glycogen, one of the sources of lactate, contributes to remyelination in vivo. J. Cell. Physiol. 232: 986–995, 2017. © 2016 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Yoshinori Ichihara
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
| | - Toru Doi
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
| | - Youngjae Ryu
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
| | - Motoshi Nagao
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
| | - Yasuhiro Sawada
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
| | - Toru Ogata
- Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons With Disabilities, Saitama, Japan
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29
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Screening and identification of neuroprotective compounds produced by Lactobacillus paracasei subsp. paracasei NTU 101. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Potential protective effects of autophagy activated in MPP+ treated astrocytes. Exp Ther Med 2016; 12:2803-2810. [PMID: 27882077 PMCID: PMC5103691 DOI: 10.3892/etm.2016.3736] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 10/21/2015] [Indexed: 12/11/2022] Open
Abstract
Astrocytes, which have various important functions, have previously been associated with Parkinsons disease (PD), particularly in 1-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models of PD. MPP+ is the toxic metabolite of MPTP and is generated by the enzymatic activity of monoamine oxidase B, which is predominantly located in astrocytes. MPP+ acts as a mitochondrial complex I inhibitor. Autophagy is an evolutionarily conserved self-digestion pathway in eukaryotic cells, which occurs in response to various types of stress, including starvation and oxidative stress. Lithium treatment has previously been shown to induce autophagy in astrocytes by inhibiting the enzyme inositol monophosphatase, which may aid in the treatment of neurodegenerative diseases, including Huntington's disease, in which the toxic protein is an autophagy substrate. Therefore, using western blotting and MTT assay, the present study aimed to investigate the protective effects of lithium-induced autophagy against astrocyte injury caused by MPP+ treatment, as well as the potential underlying mechanisms. The results of the present study suggested that lithium was able to induce autophagy in astrocytes treated with MPP+, and this likely occurred via activation of the phosphoinositide 3-kinase/AKT pathway.
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L-Lactate-Mediated Neuroprotection against Glutamate-Induced Excitotoxicity Requires ARALAR/AGC1. J Neurosci 2016; 36:4443-56. [PMID: 27098689 DOI: 10.1523/jneurosci.3691-15.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/20/2016] [Indexed: 01/20/2023] Open
Abstract
UNLABELLED ARALAR/AGC1/Slc25a12, the aspartate-glutamate carrier from brain mitochondria, is the regulatory step in the malate-aspartate NADH shuttle, MAS. MAS is used to oxidize cytosolic NADH in mitochondria, a process required to maintain oxidative glucose utilization. The role of ARALAR was analyzed in two paradigms of glutamate-induced excitotoxicity in cortical neurons: glucose deprivation and acute glutamate stimulation. ARALAR deficiency did not aggravate glutamate-induced neuronal death in vitro, although glutamate-stimulated respiration was impaired. In contrast, the presence of L-lactate as an additional source protected against glutamate-induced neuronal death in control, but not ARALAR-deficient neurons.l-Lactate supplementation increased glutamate-stimulated respiration partially prevented the decrease in the cytosolic ATP/ADP ratio induced by glutamate and substantially diminished mitochondrial accumulation of 8-oxoguanosine, a marker of reactive oxygen species production, only in the presence, but not the absence, of ARALAR. In addition,l-lactate potentiated glutamate-induced increase in cytosolic Ca(2+), in a way independent of the presence of ARALAR. Interestingly,in vivo, the loss of half-a-dose of ARALAR in aralar(+/-)mice enhanced kainic acid-induced seizures and neuronal damage with respect to control animals, in a model of excitotoxicity in which increased L-lactate levels and L-lactate consumption have been previously proven. These results suggest that,in vivo, an inefficient operation of the shuttle in the aralar hemizygous mice prevents the protective role of L-lactate on glutamate excitotoxiciy and that the entry and oxidation of L-lactate through ARALAR-MAS pathway is required for its neuroprotective function. SIGNIFICANCE STATEMENT Lactate now stands as a metabolite necessary for multiple functions in the brain and is an alternative energy source during excitotoxic brain injury. Here we find that the absence of a functional malate-aspartate NADH shuttle caused by aralar/AGC1 disruption causes a block in lactate utilization by neurons, which prevents the protective role of lactate on excitotoxicity, but not glutamate excitotoxicity itself. Thus, failure to use lactate is detrimental and is possibly responsible for the exacerbated in vivo excitotoxicity in aralar(+/-)mice.
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32
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Mason S, Reinecke CJ, Kulik W, van Cruchten A, Solomons R, van Furth AMT. Cerebrospinal fluid in tuberculous meningitis exhibits only the L-enantiomer of lactic acid. BMC Infect Dis 2016; 16:251. [PMID: 27267176 PMCID: PMC4897924 DOI: 10.1186/s12879-016-1597-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 05/27/2016] [Indexed: 11/17/2022] Open
Abstract
Background The defining feature of the cerebrospinal fluid (CSF) collected from infants and children with tuberculous meningitis (TBM), derived from an earlier untargeted nuclear magnetic resonance (NMR) metabolomics study, was highly elevated lactic acid. Undetermined was the contribution from host response (L-lactic acid) or of microbial origin (D-lactic acid), which was set out to be determined in this study. Methods In this follow-up study, we used targeted ultra-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UPLC–ESI–MS/MS) to determine the ratio of the L and D enantiomers of lactic acid in these CSF samples. Results Here we report for the first time that the lactic acid observed in the CSF of confirmed TBM cases was in the L-form and solely a response from the host to the infection, with no contribution from any bacteria. The significance of elevated lactic acid in TBM appears to be that it is a crucial energy substrate, used preferentially over glucose by microglia, and exhibits neuroprotective capabilities. Conclusion These results provide experimental evidence to support our conceptual astrocyte–microglia lactate shuttle model formulated from our previous NMR-based metabolomics study — highlighting the fact that lactic acid plays an important role in neuroinflammatory diseases such as TBM. Furthermore, this study reinforces our belief that the determination of enantiomers of metabolites corresponding to infectious diseases is of critical importance in substantiating the clinical significance of disease markers. Electronic supplementary material The online version of this article (doi:10.1186/s12879-016-1597-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shayne Mason
- Centre for Human Metabolomics, Faculty of Natural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, 2531, South Africa.
| | - Carolus J Reinecke
- Centre for Human Metabolomics, Faculty of Natural Sciences, North-West University (Potchefstroom Campus), Private Bag X6001, Potchefstroom, 2531, South Africa
| | - Willem Kulik
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Arno van Cruchten
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Regan Solomons
- Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, 7505, South Africa
| | - A Marceline Tutu van Furth
- Department of Paediatric Infectious Diseases-Immunology and Rheumatology, Vrije Universiteit Medical Centre, De Boelelaan 1117, 1081HV, Amsterdam, The Netherlands
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33
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Bisri T, Utomo BA, Fuadi I. Exogenous lactate infusion improved neurocognitive function of patients with mild traumatic brain injury. Asian J Neurosurg 2016; 11:151-9. [PMID: 27057222 PMCID: PMC4802937 DOI: 10.4103/1793-5482.145375] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Many studies showed a better recovery of cognitive function after administration of exogenous lactate during moderate-severe traumatic brain injury. However, the study evaluating lactate effect on mild traumatic brain injury is still limited. AIMS To evaluate the effect of exogenous lactate on cognitive function in mild traumatic brain injury patients. SETTINGS AND DESIGN Prospective, single blind, randomized controlled study on 60 mild traumatic brain injury patients who were undergoing neurosurgery. MATERIALS AND METHODS Subjects were randomly assigned into hyperosmolar sodium lactate (HSL) group or hyperosmolar sodium chloride (HSS) group. Patients in each group received either intravenous infusion of HSL or NaCl 3% at 1.5 ml/KgBW within 15 min before neurosurgery. During the surgery, patients in both groups received maintenance infusion of NaCl 0.9% at 1.5 ml/KgBW/hour. STATISTICAL ANALYSIS Cognitive function, as assessed by Mini-Mental State Examination (MMSE) score at 24 h, 30 and 90 days post-surgery, was analyzed by Anova repeated measures test. RESULTS The MMSE score improvement was significantly better in HSL group than HSS group (P < 0.001). In HSL group the MMSE score improved from 16.00 (13.75-18.00) at baseline to 21.00 (18.75-22.00); 25.00 (23.75-26.00); 28.00 (27.00-29.00) at 24 h, 30, 90 days post-surgery, respectively. In contrast, in HSS group the MMSE score almost unchanged at 24 h and only slightly increased at 30 and 90 days post-surgery. CONCLUSIONS Hyperosmolar sodium lactate infusion during mild traumatic brain injury improved cognitive function better than sodium chloride 3%.
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Affiliation(s)
- Tatang Bisri
- Department of Anesthesiology and Intensive Care, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia
| | - Billy A. Utomo
- Department of Anesthesiology and Intensive Care, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia
| | - Iwan Fuadi
- Department of Anesthesiology and Intensive Care, Faculty of Medicine, Universitas Padjadjaran, Hasan Sadikin Hospital, Bandung, Indonesia
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Rosafio K, Castillo X, Hirt L, Pellerin L. Cell-specific modulation of monocarboxylate transporter expression contributes to the metabolic reprograming taking place following cerebral ischemia. Neuroscience 2016; 317:108-20. [DOI: 10.1016/j.neuroscience.2015.12.052] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/17/2015] [Accepted: 12/29/2015] [Indexed: 01/23/2023]
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Hong S, Ahn JY, Cho GS, Kim IH, Cho JH, Ahn JH, Park JH, Won MH, Chen BH, Shin BN, Tae HJ, Park SM, Cho JH, Choi SY, Lee JC. Monocarboxylate transporter 4 plays a significant role in the neuroprotective mechanism of ischemic preconditioning in transient cerebral ischemia. Neural Regen Res 2015; 10:1604-11. [PMID: 26692857 PMCID: PMC4660753 DOI: 10.4103/1673-5374.167757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Monocarboxylate transporters (MCTs), which carry monocarboxylates such as lactate across biological membranes, have been associated with cerebral ischemia/reperfusion process. In this study, we studied the effect of ischemic preconditioning (IPC) on MCT4 immunoreactivity after 5 minutes of transient cerebral ischemia in the gerbil. Animals were randomly designated to four groups (sham-operated group, ischemia only group, IPC + sham-operated group and IPC + ischemia group). A serious loss of neuron was found in the stratum pyramidale of the hippocampal CA1 region (CA1), not CA2/3, of the ischemia-only group at 5 days post-ischemia; however, in the IPC + ischemia groups, neurons in the stratum pyramidale of the CA1 were well protected. Weak MCT4 immunoreactivity was found in the stratum pyramidale of the CA1 in the sham-operated group. MCT4 immunoreactivity in the stratum pyramidale began to decrease at 2 days post-ischemia and was hardly detected at 5 days post-ischemia; at this time point, MCT4 immunoreactivity was newly expressed in astrocytes. In the IPC + sham-operated group, MCT4 immunoreactivity in the stratum pyramidale of the CA1 was increased compared with the sham-operated group, and, in the IPC + ischemia group, MCT4 immunoreactivity was also increased in the stratum pyramidale compared with the ischemia only group. Briefly, present findings show that IPC apparently protected CA1 pyramidal neurons and increased or maintained MCT4 expression in the stratum pyramidale of the CA1 after transient cerebral ischemia. Our findings suggest that MCT4 appears to play a significant role in the neuroprotective mechanism of IPC in the gerbil with transient cerebral ischemia.
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Affiliation(s)
- Seongkweon Hong
- Department of Surgery, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Ji Yun Ahn
- Department of Emergency Medicine, Sacred Heart Hospital, College of Medicine, Hallym University, Anyang, South Korea ; Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Geum-Sil Cho
- Department of Neuroscience, College of Medicine, Korea University, Seoul, South Korea
| | - In Hye Kim
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Jeong Hwi Cho
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Ji Hyeon Ahn
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Joon Ha Park
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Moo-Ho Won
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Bai Hui Chen
- Department of Physiology, College of Medicine, Hallym University, Chuncheon, South Korea
| | - Bich-Na Shin
- Department of Physiology, College of Medicine, Hallym University, Chuncheon, South Korea
| | - Hyun-Jin Tae
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, South Korea
| | - Seung Min Park
- Department of Emergency Medicine, Sacred Heart Hospital, College of Medicine, Hallym University, Anyang, South Korea ; Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Jun Hwi Cho
- Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon, South Korea
| | - Soo Young Choi
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, South Korea
| | - Jae-Chul Lee
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, South Korea
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Dennis A, Thomas AG, Rawlings NB, Near J, Nichols TE, Clare S, Johansen-Berg H, Stagg CJ. An Ultra-High Field Magnetic Resonance Spectroscopy Study of Post Exercise Lactate, Glutamate and Glutamine Change in the Human Brain. Front Physiol 2015; 6:351. [PMID: 26732236 PMCID: PMC4681779 DOI: 10.3389/fphys.2015.00351] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 11/09/2015] [Indexed: 12/01/2022] Open
Abstract
During strenuous exercise there is a progressive increase in lactate uptake and metabolism into the brain as workload and plasma lactate levels increase. Although it is now widely accepted that the brain can metabolize lactate, few studies have directly measured brain lactate following vigorous exercise. Here, we used ultra-high field magnetic resonance spectroscopy of the brain to obtain static measures of brain lactate, as well as brain glutamate and glutamine after vigorous exercise. The aims of our experiment were to (a) track the changes in brain lactate following recovery from exercise, and (b) to simultaneously measure the signals from brain glutamate and glutamine. The results of our experiment showed that vigorous exercise resulted in a significant increase in brain lactate. Furthermore, both glutamate and glutamine were successfully resolved, and as expected, although contrary to some previous reports, we did not observe any significant change in either amino acid after exercise. We did however observe a negative correlation between glutamate and a measure of fitness. These results support the hypothesis that peripherally derived lactate is taken up by the brain when available. Our data additionally highlight the potential of ultra-high field MRS as a non-invasive way of measuring multiple brain metabolite changes with exercise.
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Affiliation(s)
- Andrea Dennis
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford Oxford, UK
| | - Adam G Thomas
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of OxfordOxford, UK; Section on Functional Imaging Methods, National Institute of Mental Health, National Institutes of Health, Department of Health and Human ServicesBethesda, MD, USA
| | - Nancy B Rawlings
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford Oxford, UK
| | - Jamie Near
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of OxfordOxford, UK; Douglas Mental Health University Institute and Department of Psychiatry, McGill UniversityMontreal, QC, Canada
| | - Thomas E Nichols
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of OxfordOxford, UK; Department of Statistics and Warwick Manufacturing Group, University of WarwickCoventry, UK
| | - Stuart Clare
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford Oxford, UK
| | - Heidi Johansen-Berg
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford Oxford, UK
| | - Charlotte J Stagg
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of OxfordOxford, UK; Physiological Neuroimaging Group, Oxford Centre for Human Brain Activity (OHBA), University of OxfordOxford, UK
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37
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Quintard H, Patet C, Zerlauth JB, Suys T, Bouzat P, Pellerin L, Meuli R, Magistretti PJ, Oddo M. Improvement of Neuroenergetics by Hypertonic Lactate Therapy in Patients with Traumatic Brain Injury Is Dependent on Baseline Cerebral Lactate/Pyruvate Ratio. J Neurotrauma 2015; 33:681-7. [PMID: 26421521 PMCID: PMC4827289 DOI: 10.1089/neu.2015.4057] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Energy dysfunction is associated with worse prognosis after traumatic brain injury (TBI). Recent data suggest that hypertonic sodium lactate infusion (HL) improves energy metabolism after TBI. Here, we specifically examined whether the efficacy of HL (3h infusion, 30–40 μmol/kg/min) in improving brain energetics (using cerebral microdialysis [CMD] glucose as a main therapeutic end-point) was dependent on baseline cerebral metabolic state (assessed by CMD lactate/pyruvate ratio [LPR]) and cerebral blood flow (CBF, measured with perfusion computed tomography [PCT]). Using a prospective cohort of 24 severe TBI patients, we found CMD glucose increase during HL was significant only in the subgroup of patients with elevated CMD LPR >25 (n = 13; +0.13 [95% confidence interval (CI) 0.08–0.19] mmol/L, p < 0.001; vs. +0.04 [–0.05–0.13] in those with normal LPR, p = 0.33, mixed-effects model). In contrast, CMD glucose increase was independent from baseline CBF (coefficient +0.13 [0.04–0.21] mmol/L when global CBF was <32.5 mL/100 g/min vs. +0.09 [0.04–0.14] mmol/L at normal CBF, both p < 0.005) and systemic glucose. Our data suggest that improvement of brain energetics upon HL seems predominantly dependent on baseline cerebral metabolic state and support the concept that CMD LPR – rather than CBF – could be used as a diagnostic indication for systemic lactate supplementation following TBI.
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Affiliation(s)
- Hervé Quintard
- 1 Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland .,2 Department of Anesthesia and Intensive Care, Nice University Hospital , Nice, France
| | - Camille Patet
- 1 Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland
| | - Jean-Baptiste Zerlauth
- 3 Department of Medical Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland
| | - Tamarah Suys
- 1 Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland
| | - Pierre Bouzat
- 1 Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland .,4 Department of Anesthesia and Intensive Care, Grenoble University Hospital , Grenoble, France
| | - Luc Pellerin
- 5 Institute of Physiology, University of Lausanne , Lausanne, Switzerland
| | - Reto Meuli
- 3 Department of Medical Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland
| | - Pierre J Magistretti
- 6 Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal, Kingdom of Saudi Arabia .,7 Centre de Neurosciences Psychiatriques, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland .,8 Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute , Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Mauro Oddo
- 1 Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne University Hospital , Lausanne, Switzerland
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Abstract
Neuroglia, the "glue" that fills the space between neurons in the central nervous system, takes active part in nerve cell signaling. Neuroglial cells, astroglia, oligodendroglia, and microglia, are together about as numerous as neurons in the brain as a whole, and in the cerebral cortex grey matter, but the proportion varies widely among brain regions. Glial volume, however, is less than one-fifth of the tissue volume in grey matter. When stimulated by neurons or other cells, neuroglial cells release gliotransmitters by exocytosis, similar to neurotransmitter release from nerve endings, or by carrier-mediated transport or channel flux through the plasma membrane. Gliotransmitters include the common neurotransmitters glutamate and GABA, the nonstandard amino acid d-serine, the high-energy phosphate ATP, and l-lactate. The latter molecule is a "buffer" between glycolytic and oxidative metabolism as well as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies.
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Affiliation(s)
- Vidar Gundersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Jon Storm-Mathisen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Linda Hildegard Bergersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
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Magistretti PJ, Allaman I. A cellular perspective on brain energy metabolism and functional imaging. Neuron 2015; 86:883-901. [PMID: 25996133 DOI: 10.1016/j.neuron.2015.03.035] [Citation(s) in RCA: 756] [Impact Index Per Article: 84.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The energy demands of the brain are high: they account for at least 20% of the body's energy consumption. Evolutionary studies indicate that the emergence of higher cognitive functions in humans is associated with an increased glucose utilization and expression of energy metabolism genes. Functional brain imaging techniques such as fMRI and PET, which are widely used in human neuroscience studies, detect signals that monitor energy delivery and use in register with neuronal activity. Recent technological advances in metabolic studies with cellular resolution have afforded decisive insights into the understanding of the cellular and molecular bases of the coupling between neuronal activity and energy metabolism and point at a key role of neuron-astrocyte metabolic interactions. This article reviews some of the most salient features emerging from recent studies and aims at providing an integration of brain energy metabolism across resolution scales.
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Affiliation(s)
- Pierre J Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia; Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland; Center for Psychiatric Neurosciences, Department of Psychiatry, University of Lausanne, Lausanne 1008, Switzerland.
| | - Igor Allaman
- Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
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40
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Turovsky E, Karagiannis A, Abdala AP, Gourine AV. Impaired CO2 sensitivity of astrocytes in a mouse model of Rett syndrome. J Physiol 2015; 593:3159-68. [PMID: 25981852 PMCID: PMC4532534 DOI: 10.1113/jp270369] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/11/2015] [Indexed: 12/13/2022] Open
Abstract
Rett syndrome, a prototypical neurological disorder caused by loss of function of the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2) gene, is associated with a severely disordered breathing pattern and reduced ventilatory CO2 sensitivity. In a mouse model of Rett syndrome (MeCP2 knockout), re-introduction of the MeCP2 gene selectively in astrocytes rescues normal respiratory phenotype. In the present study we determined whether the metabolic and/or signalling functions of astrocytes are affected by testing the hypotheses that in conditions of MeCP2 deficiency, medullary astrocytes are unable to produce/release appropriate amounts of lactate or detect changes in PCO2/[H(+) ], or both. No differences in tonic or hypoxia-induced release of lactate from the ventral surface of the medulla oblongata or cerebral cortex in brain slices of MeCP2-knockout and wild-type mice were found. In brainstem slices of wild-type mice, respiratory acidosis triggered robust elevations in [Ca(2+) ]i in astrocytes residing near the ventral surface of the medulla oblongata. The magnitude of CO2 -induced [Ca(2+) ]i responses in medullary astrocytes was markedly reduced in conditions of MeCP2 deficiency, whereas [Ca(2+) ]i responses to ATP were unaffected. These data suggest that (i) metabolic function of astrocytes in releasing lactate into the extracellular space is not affected by MeCP2 deficiency, and (ii) MeCP2 deficiency impairs the ability of medullary astrocytes to sense changes in PCO2/[H(+) ]. Taken together with the evidence of severely blunted ventilatory sensitivity to CO2 in mice with conditional MeCP2 deletion in astroglia, these data support the hypothesis of an important role played by astrocytes in central respiratory CO2 /pH chemosensitivity.
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Affiliation(s)
- Egor Turovsky
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.,Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Anastassios Karagiannis
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ana Paula Abdala
- School of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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41
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Guitart K, Loers G, Schachner M, Kleene R. Prion protein regulates glutathione metabolism and neural glutamate and cysteine uptake via excitatory amino acid transporter 3. J Neurochem 2015; 133:558-71. [PMID: 25692227 DOI: 10.1111/jnc.13071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 01/29/2015] [Accepted: 02/08/2015] [Indexed: 01/02/2023]
Abstract
Prion protein (PrP) plays crucial roles in regulating antioxidant systems to improve cell defenses against cellular stress. Here, we show that the interactions of PrP with the excitatory amino acid transporter 3 (EAAT3), γ-glutamyl transpeptidase (γ-GT), and multi-drug resistance protein 1 (MRP1) in astrocytes and the interaction between PrP and EAAT3 in neurons regulate the astroglial and neuronal metabolism of the antioxidant glutathione. Ablation of PrP in astrocytes and cerebellar neurons leads to dysregulation of EAAT3-mediated uptake of glutamate and cysteine, which are precursors for the synthesis of glutathione. In PrP-deficient astrocytes, levels of intracellular glutathione are increased, and under oxidative stress, levels of extracellular glutathione are increased, due to (i) increased glutathione release via MRP1 and (ii) reduced activity of the glutathione-degrading enzyme γ-GT. In PrP-deficient cerebellar neurons, cell death is enhanced under oxidative stress and glutamate excitotoxicity, when compared to wild-type cerebellar neurons. These results indicate a functional interplay of PrP with EAAT3, MRP1 and γ-GT in astrocytes and of PrP and EAAT3 in neurons, suggesting that these interactions play an important role in the metabolic cross-talk between astrocytes and neurons and in protection of neurons by astrocytes from oxidative and glutamate-induced cytotoxicity. Interactions of prion protein (PrP) with excitatory amino acid transporter 3 (EAAT3), γ-glutamyl transpeptidase (GGT) and multi-drug resistance protein 1 (MRP1) regulate the astroglial and neuronal metabolism of glutathione (GSH) which protects cells against the cytotoxic oxidative stress. PrP controls the release of GSH from astrocytes via MRP1 and regulates the hydrolysis of extracellular GSH by GGT as well as the neuronal and astroglial glutamate and cysteine uptake via EAAT3.
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Affiliation(s)
- Kathrin Guitart
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
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42
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Allaman I, Bélanger M, Magistretti PJ. Methylglyoxal, the dark side of glycolysis. Front Neurosci 2015; 9:23. [PMID: 25709564 PMCID: PMC4321437 DOI: 10.3389/fnins.2015.00023] [Citation(s) in RCA: 354] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/13/2015] [Indexed: 12/05/2022] Open
Abstract
Glucose is the main energy substrate for the brain. There is now extensive evidence indicating that the metabolic profile of neural cells with regard to glucose utilization and glycolysis rate is not homogenous, with a marked propensity for glycolytic glucose processing in astrocytes compared to neurons. Methylglyoxal, a highly reactive dicarbonyl compound, is inevitably formed as a by-product of glycolysis. Methylglyoxal is a major cell-permeant precursor of advanced glycation end-products (AGEs), which are associated with several pathologies including diabetes, aging and neurodegenerative diseases. In normal situations, cells are protected against methylglyoxal toxicity by different mechanisms and in particular the glyoxalase system, which represents the most important pathway for the detoxification of methylglyoxal. While the neurotoxic effects of methylglyoxal and AGEs are well characterized, our understanding the glyoxalase system in the brain is more scattered. Considering the high energy requirements (i.e., glucose) of the brain, one should expect that the cerebral glyoxalase system is adequately fitted to handle methylglyoxal toxicity. This review focuses on our actual knowledge on the cellular aspects of the glyoxalase system in brain cells, in particular with regard to its activity in astrocytes and neurons. A main emerging concept is that these two neural cell types have different and energetically adapted glyoxalase defense mechanisms which may serve as protective mechanism against methylglyoxal-induced cellular damage.
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Affiliation(s)
- Igor Allaman
- Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
| | - Mireille Bélanger
- Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
| | - Pierre J Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology Thuwal, Saudi Arabia ; Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
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43
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Deitmer JW, Theparambil SM, Ruminot I, Becker HM. The role of membrane acid/base transporters and carbonic anhydrases for cellular pH and metabolic processes. Front Neurosci 2015; 8:430. [PMID: 25601823 PMCID: PMC4283522 DOI: 10.3389/fnins.2014.00430] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/09/2014] [Indexed: 11/17/2022] Open
Affiliation(s)
- Joachim W Deitmer
- General Zoology, FB Biology, University of Kaiserslautern Kaiserslautern, Germany
| | | | - Iván Ruminot
- General Zoology, FB Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Holger M Becker
- Zoology/Membrane Transport, FB Biology, University of Kaiserslautern Kaiserslautern, Germany
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44
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Duarte JMN, Girault FM, Gruetter R. Brain energy metabolism measured by (13)C magnetic resonance spectroscopy in vivo upon infusion of [3-(13)C]lactate. J Neurosci Res 2014; 93:1009-18. [PMID: 25522255 DOI: 10.1002/jnr.23531] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 11/11/2022]
Abstract
The brain uses lactate produced by glycolysis as an energy source. How lactate originated from the blood stream is used to fuel brain metabolism is not clear. The current study measures brain metabolic fluxes and estimates the amount of pyruvate that becomes labeled in glial and neuronal compartments upon infusion of [3-(13)C]lactate. For that, labeling incorporation into carbons of glutamate and glutamine was measured by (13)C magnetic resonance spectroscopy at 14.1 T and analyzed with a two-compartment model of brain metabolism to estimate rates of mitochondrial oxidation, glial pyruvate carboxylation, and the glutamate-glutamine cycle as well as pyruvate fractional enrichments. Extracerebral lactate at supraphysiological levels contributes at least two-fold more to replenish the neuronal than the glial pyruvate pools. The rates of mitochondrial oxidation in neurons and glia, pyruvate carboxylase, and glutamate-glutamine cycles were similar to those estimated by administration of (13)C-enriched glucose, the main fuel of brain energy metabolism. These results are in agreement with primary utilization of exogenous lactate in neurons rather than astrocytes.
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Affiliation(s)
- João M N Duarte
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Freya-Merret Girault
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de 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
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45
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Liu H, Radlowski EC, Conrad MS, Li Y, Dilger RN, Johnson RW. Early supplementation of phospholipids and gangliosides affects brain and cognitive development in neonatal piglets. J Nutr 2014; 144:1903-9. [PMID: 25411030 PMCID: PMC4230208 DOI: 10.3945/jn.114.199828] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/12/2014] [Accepted: 09/09/2014] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Because human breast milk is a rich source of phospholipids and gangliosides and breastfed infants have improved learning compared with formula-fed infants, the importance of dietary phospholipids and gangliosides for brain development is of interest. OBJECTIVE We sought to determine the effects of phospholipids and gangliosides on brain and cognitive development. METHODS Male and female piglets from multiple litters were artificially reared and fed formula containing 0% (control), 0.8%, or 2.5% Lacprodan PL-20 (PL-20; Arla Foods Ingredients), a phospholipid/ganglioside supplement, from postnatal day (PD) 2 to PD28. Beginning on PD14, performance in a spatial T-maze task was assessed. At PD28, brain MRI data were acquired and piglets were killed to obtain hippocampal tissue for metabolic profiling. RESULTS Diet affected maze performance, with piglets that were fed 0.8% and 2.5% PL-20 making fewer errors than control piglets (80% vs. 75% correct on average; P < 0.05) and taking less time to make a choice (3 vs. 5 s/trial; P < 0.01). Mean brain weight was 5% higher for piglets fed 0.8% and 2.5% PL-20 (P < 0.05) than control piglets, and voxel-based morphometry revealed multiple brain areas with greater volumes and more gray and white matter in piglets fed 0.8% and 2.5% PL-20 than in control piglets. Metabolic profiling of hippocampal tissue revealed that multiple phosphatidylcholine-related metabolites were altered by diet. CONCLUSION In summary, dietary phospholipids and gangliosides improved spatial learning and affected brain growth and composition in neonatal piglets.
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Affiliation(s)
- Hongnan Liu
- Department of Animal Sciences, Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China
| | - Emily C Radlowski
- Department of Animal Sciences, Division of Nutritional Sciences, and
| | - Matthew S Conrad
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL; and
| | - Yao Li
- Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China
| | - Ryan N Dilger
- Department of Animal Sciences, Division of Nutritional Sciences, and Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL; and
| | - Rodney W Johnson
- Department of Animal Sciences, Division of Nutritional Sciences, and Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL; and
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46
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Chambers TW, Daly TP, Hockley A, Brown AM. Contribution of glycogen in supporting axon conduction in the peripheral and central nervous systems: the role of lactate. Front Neurosci 2014; 8:378. [PMID: 25505379 PMCID: PMC4243571 DOI: 10.3389/fnins.2014.00378] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/05/2014] [Indexed: 11/25/2022] Open
Abstract
The role of glycogen in the central nervous system is intimately linked with the glycolytic pathway. Glycogen is synthesized from glucose, the primary substrate for glycolysis, and degraded to glucose-6-phosphate. The metabolic cost of shunting glucose via glycogen exceeds that of simple phosphorylation of glucose to glucose-6-phosphate by hexokinase; thus, there must be a metabolic advantage in utilizing this shunt pathway. The dogmatic view of glycogen as a storage depot persists, based on initial descriptions of glycogen supporting neural function in the face of aglycemia. The variable latency to conduction failure, dependent upon tissue glycogen levels, provided convincing evidence of the role played by glycogen in supporting neural function. Glycogen is located predominantly in astrocytes in the central nervous system, thus for glycogen to benefit neural elements, intercellular metabolic communication must exist in the form of astrocyte to neuron substrate transfer. Experimental evidence supports a model where glycogen is metabolized to lactate in astrocytes, with cellular expression of monocarboxylate transporters and enzymes appropriately located for lactate shuttling between astrocytes and neural elements, where lactate acts as a substrate for oxidative metabolism. Biosensor recordings have demonstrated a significant steady concentration of lactate present on the periphery of both central white matter and peripheral nerve under unstimulated baseline conditions, indicating continuous cellular efflux of lactate to the interstitium. The existence of this lactate pool argues we must reexamine the "on demand" shuttling of lactate between cellular elements, and suggests continuous lactate efflux surplus to immediate neural requirements.
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Affiliation(s)
- Tom W. Chambers
- School of Life Sciences, Queen's Medical Centre, University of NottinghamNottingham, UK
| | - Timothy P. Daly
- School of Life Sciences, Queen's Medical Centre, University of NottinghamNottingham, UK
| | - Adam Hockley
- School of Life Sciences, Queen's Medical Centre, University of NottinghamNottingham, UK
| | - Angus M. Brown
- School of Life Sciences, Queen's Medical Centre, University of NottinghamNottingham, UK
- Department of Neurology, University of WashingtonSeattle, WA, USA
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47
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Schurr A. Cerebral glycolysis: a century of persistent misunderstanding and misconception. Front Neurosci 2014; 8:360. [PMID: 25477776 PMCID: PMC4237041 DOI: 10.3389/fnins.2014.00360] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/21/2014] [Indexed: 11/18/2022] Open
Abstract
Since its discovery in 1780, lactate (lactic acid) has been blamed for almost any illness outcome in which its levels are elevated. Beginning in the mid-1980s, studies on both muscle and brain tissues, have suggested that lactate plays a role in bioenergetics. However, great skepticism and, at times, outright antagonism has been exhibited by many to any perceived role for this monocarboxylate in energy metabolism. The present review attempts to trace the negative attitudes about lactate to the first four or five decades of research on carbohydrate metabolism and its dogma according to which lactate is a useless anaerobic end-product of glycolysis. The main thrust here is the review of dozens of scientific publications, many by the leading scientists of their times, through the first half of the twentieth century. Consequently, it is concluded that there exists a barrier, described by Howard Margolis as “habit of mind,” that many scientists find impossible to cross. The term suggests “entrenched responses that ordinarily occur without conscious attention and that, even if noticed, are hard to change.” Habit of mind has undoubtedly played a major role in the above mentioned negative attitudes toward lactate. As early as the 1920s, scientists investigating brain carbohydrate metabolism had discovered that lactate can be oxidized by brain tissue preparations, yet their own habit of mind redirected them to believe that such an oxidation is simply a disposal mechanism of this “poisonous” compound. The last section of the review invites the reader to consider a postulated alternative glycolytic pathway in cerebral and, possibly, in most other tissues, where no distinction is being made between aerobic and anaerobic glycolysis; lactate is always the glycolytic end product. Aerobically, lactate is readily shuttled and transported into the mitochondrion, where it is converted to pyruvate via a mitochondrial lactate dehydrogenase (mLDH) and then is entered the tricarboxylic acid (TCA) cycle.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine Louisville, KY, USA
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48
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An RNA-sequencing transcriptome and splicing database of glia, neurons, and vascular cells of the cerebral cortex. J Neurosci 2014; 34:11929-47. [PMID: 25186741 DOI: 10.1523/jneurosci.1860-14.2014] [Citation(s) in RCA: 3536] [Impact Index Per Article: 353.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The major cell classes of the brain differ in their developmental processes, metabolism, signaling, and function. To better understand the functions and interactions of the cell types that comprise these classes, we acutely purified representative populations of neurons, astrocytes, oligodendrocyte precursor cells, newly formed oligodendrocytes, myelinating oligodendrocytes, microglia, endothelial cells, and pericytes from mouse cerebral cortex. We generated a transcriptome database for these eight cell types by RNA sequencing and used a sensitive algorithm to detect alternative splicing events in each cell type. Bioinformatic analyses identified thousands of new cell type-enriched genes and splicing isoforms that will provide novel markers for cell identification, tools for genetic manipulation, and insights into the biology of the brain. For example, our data provide clues as to how neurons and astrocytes differ in their ability to dynamically regulate glycolytic flux and lactate generation attributable to unique splicing of PKM2, the gene encoding the glycolytic enzyme pyruvate kinase. This dataset will provide a powerful new resource for understanding the development and function of the brain. To ensure the widespread distribution of these datasets, we have created a user-friendly website (http://web.stanford.edu/group/barres_lab/brain_rnaseq.html) that provides a platform for analyzing and comparing transciption and alternative splicing profiles for various cell classes in the brain.
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Galeffi F, Shetty PK, Sadgrove MP, Turner DA. Age-related metabolic fatigue during low glucose conditions in rat hippocampus. Neurobiol Aging 2014; 36:982-92. [PMID: 25443286 DOI: 10.1016/j.neurobiolaging.2014.09.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 09/03/2014] [Accepted: 09/17/2014] [Indexed: 12/14/2022]
Abstract
Previous reports have indicated that with aging, intrinsic brain tissue changes in cellular bioenergetics may hamper the brain's ability to cope with metabolic stress. Therefore, we analyzed the effects of age on neuronal sensitivity to glucose deprivation by monitoring changes in field excitatory postsynaptic potentials (fEPSPs), tissue Po2, and NADH fluorescence imaging in the CA1 region of hippocampal slices obtained from F344 rats (1-2, 3-6, 12-20, and >22 months). Forty minutes of moderate low glucose (2.5 mM) led to approximately 80% decrease of fEPSP amplitudes and NADH decline in all 4 ages that reversed after reintroduction of 10 mM glucose. However, tissue slices from 12 to 20 months and >22-month-old rats were more vulnerable to low glucose: fEPSPs decreased by 50% on average 8 minutes faster compared with younger slices. Tissue oxygen utilization increased after onset of 2.5 mM glucose in all ages of tissue slices, which persisted for 40 minutes in younger tissue slices. But, in older tissue slices the increased oxygen utilization slowly faded and tissue Po2 levels increased toward baseline values after approximately 25 minutes of glucose deprivation. In addition, with age the ability to regenerate NADH after oxidation was diminished. The NAD(+)/NADH ratio remained relatively oxidized after low glucose, even during recovery. In young slices, glycogen levels were stable throughout the exposure to low glucose. In contrast, with aging utilization of glycogen stores was increased during low glucose, particularly in hippocampal slices from >22 months old rats, indicating both inefficient metabolism and increased demand for glucose. Lactate addition (20 mM) improved oxidative metabolism by directly supplementing the mitochondrial NADH pool and maintained fEPSPs in young as well as aged tissue slices, indicating that inefficient metabolism in the aging tissue can be improved by directly enhancing NADH regeneration.
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Affiliation(s)
- Francesca Galeffi
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA.
| | - Pavan K Shetty
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA
| | - Matthew P Sadgrove
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA
| | - Dennis A Turner
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
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50
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Sayre NL, Chen Y, Sifuentes M, Stoveken B, Lechleiter JD. Purinergic receptor stimulation decreases ischemic brain damage by energizing astrocyte mitochondria. ADVANCES IN NEUROBIOLOGY 2014; 11:121-50. [PMID: 25236727 DOI: 10.1007/978-3-319-08894-5_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
As a leading cause of death in the world, cerebral ischemic stroke has limited treatment options. The lack of glucose and oxygen after stroke is particularly harmful in the brain because neuronal metabolism accounts for significantly more energy consumption per gram of body weight compared to other organs. Our laboratory has identified mitochondrial metabolism of astrocytes to be a key target for pharmacologic intervention, not only because astrocytes play a central role in regulating brain metabolism, but also because they are essential for neuronal health and support. Here we review current literature pertaining to the pathobiology of stroke, along with the role of astrocytes and metabolism in stroke. We also discuss our research, which has revealed that pharmacologic stimulation of metabotropic P2Y1 receptor signaling in astrocytes can increase mitochondrial energy production and also reduce damage after stroke.
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Affiliation(s)
- Naomi L Sayre
- Department of Cellular and Structural Biology, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
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