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Xu Y, Kusuyama J, Osana S, Matsuhashi S, Li L, Takada H, Inada H, Nagatomi R. Lactate promotes neuronal differentiation of SH-SY5Y cells by lactate-responsive gene sets through NDRG3-dependent and -independent manners. J Biol Chem 2023:104802. [PMID: 37172727 DOI: 10.1016/j.jbc.2023.104802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 04/23/2023] [Accepted: 05/01/2023] [Indexed: 05/15/2023] Open
Abstract
Lactate serves as the major glucose alternative to an energy substrate in the brain. Lactate level is increased in the fetal brain from the middle stage of gestation, indicating the involvement of lactate in brain development and neuronal differentiation. Recent reports show that lactate functions as a signaling molecule to regulate gene expression and protein stability. However, the roles of lactate signaling in neuronal cells remain unknown. Here, we showed that lactate promotes the all stages of neuronal differentiation of SH-SY5Y and Neuro2A, human and mouse neuroblastoma cell lines, characterized by increased neuronal marker expression and the rates of neurites extension. Transcriptomics revealed many lactate-responsive genes sets such as SPARCL1 in SH-SY5Y, Neuro2A, and primary embryonic mouse neuronal cells. The effects of lactate on neuronal function were mainly mediated through monocarboxylate transporters 1 (MCT1). We found that NDRG family member 3 (NDRG3), a lactate-binding protein, was highly expressed and stabilized by lactate treatment during neuronal differentiation. Combinative RNA-seq of SH-SY5Y with lactate treatment and NDRG3 knockdown shows that the promotive effects of lactate on neural differentiation are regulated through NDRG3-dependent and independent manners. Moreover, we identified TEA domain family member 1 (TEAD1) and ETS-related transcription factor 4 (ELF4) are the specific transcription factors that are regulated by both lactate and NDRG3 in neuronal differentiation. TEAD1 and ELF4 differently affect the expression of neuronal marker genes in SH-SY5Y cells. These results highlight the biological roles of extracellular and intracellular lactate as a critical signaling molecule that modifies neuronal differentiation.
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Affiliation(s)
- Yidan Xu
- Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Joji Kusuyama
- Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan; Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan; Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan; Department of Biosignals and Inheritance, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
| | - Shion Osana
- Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan; Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan; Graduate School of Informatics and Engineering, University of Electro-Communications
| | - Satayuki Matsuhashi
- Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
| | - Longfei Li
- Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroaki Takada
- Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
| | - Hitoshi Inada
- Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan; Department of Developmental Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ryoichi Nagatomi
- Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan; Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan.
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Briquet M, Rocher AB, Alessandri M, Rosenberg N, de Castro Abrantes H, Wellbourne-Wood J, Schmuziger C, Ginet V, Puyal J, Pralong E, Daniel RT, Offermanns S, Chatton JY. Activation of lactate receptor HCAR1 down-modulates neuronal activity in rodent and human brain tissue. J Cereb Blood Flow Metab 2022; 42:1650-1665. [PMID: 35240875 PMCID: PMC9441721 DOI: 10.1177/0271678x221080324] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lactate can be used by neurons as an energy substrate to support their activity. Evidence suggests that lactate also acts on a metabotropic receptor called HCAR1, first described in the adipose tissue. Whether HCAR1 also modulates neuronal circuits remains unclear. In this study, using qRT-PCR, we show that HCAR1 is present in the human brain of epileptic patients who underwent resective surgery. In brain slices from these patients, pharmacological HCAR1 activation using a non-metabolized agonist decreased the frequency of both spontaneous neuronal Ca2+ spiking and excitatory post-synaptic currents (sEPSCs). In mouse brains, we found HCAR1 expression in different regions using a fluorescent reporter mouse line and in situ hybridization. In the dentate gyrus, HCAR1 is mainly present in mossy cells, key players in the hippocampal excitatory circuitry and known to be involved in temporal lobe epilepsy. By using whole-cell patch clamp recordings in mouse and rat slices, we found that HCAR1 activation causes a decrease in excitability, sEPSCs, and miniature EPSCs frequency of granule cells, the main output of mossy cells. Overall, we propose that lactate can be considered a neuromodulator decreasing synaptic activity in human and rodent brains, which makes HCAR1 an attractive target for the treatment of epilepsy.
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Affiliation(s)
- Marc Briquet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anne-Bérengère Rocher
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Maxime Alessandri
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Nadia Rosenberg
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | | | - Joel Wellbourne-Wood
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Céline Schmuziger
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Vanessa Ginet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Etienne Pralong
- Department of Neurosurgery Service, University Hospital of Lausanne and Faculty of Biology and Medicine, UNIL, Lausanne, Switzerland
| | - Roy Thomas Daniel
- Department of Neurosurgery Service, University Hospital of Lausanne and Faculty of Biology and Medicine, UNIL, Lausanne, Switzerland
| | - Stefan Offermanns
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Cellular Imaging Facility, University of Lausanne, Lausanne, Switzerland
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Kobayashi R, Maruoka J, Norimoto H, Ikegaya Y, Kume K, Ohsawa M. Involvement of l-lactate in hippocampal dysfunction of type I diabetes. J Pharmacol Sci 2019; 141:79-82. [PMID: 31586517 DOI: 10.1016/j.jphs.2019.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/26/2019] [Accepted: 09/03/2019] [Indexed: 11/27/2022] Open
Abstract
Hippocampal neurons play a crucial role in memory formation. Accumulating evidence raises the possibility that hippocampal sharp-wave ripples (SW-Rs) are involved in memory consolidation. Here, we examined in an animal model of diabetes and found the amplitude of SW-Rs in diabetic mice were smaller than control group and were rescued by acute application of l-lactate, a major neural energy source. The cognitive impairment in diabetic mice was alleviated by intracerebroventricular l-lactate treatment. Our results suggested that l-lactate is important for hippocampal dysfunction in diabetes.
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Affiliation(s)
- Riho Kobayashi
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Junya Maruoka
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hiroaki Norimoto
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Masahiro Ohsawa
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
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Miyamoto K, Ishikura KI, Kume K, Ohsawa M. Astrocyte-neuron lactate shuttle sensitizes nociceptive transmission in the spinal cord. Glia 2018; 67:27-36. [DOI: 10.1002/glia.23474] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 05/17/2018] [Accepted: 05/25/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Keisuke Miyamoto
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Kei-ichiro Ishikura
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Kazuhiko Kume
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Masahiro Ohsawa
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
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Metabolic regulation of synaptic activity. Rev Neurosci 2018; 29:825-835. [DOI: 10.1515/revneuro-2017-0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/16/2018] [Indexed: 12/20/2022]
Abstract
Abstract
Brain tissue is bioenergetically expensive. In humans, it composes approximately 2% of body weight and accounts for approximately 20% of calorie consumption. The brain consumes energy mostly for ion and neurotransmitter transport, a process that occurs primarily in synapses. Therefore, synapses are expensive for any living creature who has brain. In many brain diseases, synapses are damaged earlier than neurons start dying. Synapses may be considered as vulnerable sites on a neuron. Ischemic stroke, an acute disturbance of blood flow in the brain, is an example of a metabolic disease that affects synapses. The associated excessive glutamate release, called excitotoxicity, is involved in neuronal death in brain ischemia. Another example of a metabolic disease is hypoglycemia, a complication of diabetes mellitus, which leads to neuronal death and brain dysfunction. However, synapse function can be corrected with “bioenergetic medicine”. In this review, a ketogenic diet is discussed as a curative option. In support of a ketogenic diet, whereby carbohydrates are replaced for fats in daily meals, epileptic seizures can be terminated. In this review, we discuss possible metabolic sensors in synapses. These may include molecules that perceive changes in composition of extracellular space, for instance, ketone body and lactate receptors, or molecules reacting to changes in cytosol, for instance, KATP channels or AMP kinase. Inhibition of endocytosis is believed to be a universal synaptic mechanism of adaptation to metabolic changes.
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Abstract
Lactate in the brain has long been associated with ischaemia; however, more recent evidence shows that it can be found there under physiological conditions. In the brain, lactate is formed predominantly in astrocytes from glucose or glycogen in response to neuronal activity signals. Thus, neurons and astrocytes show tight metabolic coupling. Lactate is transferred from astrocytes to neurons to match the neuronal energetic needs, and to provide signals that modulate neuronal functions, including excitability, plasticity and memory consolidation. In addition, lactate affects several homeostatic functions. Overall, lactate ensures adequate energy supply, modulates neuronal excitability levels and regulates adaptive functions in order to set the 'homeostatic tone' of the nervous system.
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Reduction in N-methyl-D-aspartate Receptor-mediated Cell Death in Hippocampal Neurons by Glucose Reduction Preconditioning. J Neurosurg Anesthesiol 2017; 29:448-457. [PMID: 28368913 DOI: 10.1097/ana.0000000000000431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Repeated episodes of reduced glucose availability can precondition the brain against damage caused by severe hypoglycemia. Because N-methyl-D-aspartate (NMDA) receptor activation may contribute to neuronal loss in the hippocampus following glucose deprivation, we tested the hypothesis that preconditioning with reduced glucose decreased NMDA receptor-mediated cell death in hippocampal neurons. METHODS Hippocampal slice cultures from 7-day old rats were used to study glucose reduction preconditioning and N-methyl-D-aspartate receptor (NMDAR)-mediated cell death. Preconditioning involved reductions in glucose to the following levels: 0.1 mM, 0.5, or 1.0 mM for 30 minutes, 60 minutes, or 90 minutes on 3 consecutive days. Cell death following 1-hour total glucose deprivation was measured with a vital dye technique (SYTOX fluorescence). As an index of NMDAR activity, cell death following application of 1 mM NMDA, was also measured. RESULTS A preconditioning protocol of 30 minutes of 0.1 mM glucose per day for 3 days reduced cell death following 1-hour total glucose by 65% to 70%, depending on cellular region. No reduction in NMDAR-mediated cell death was seen following any of the preconditioning treatments. However, when NMDAR-mediated cell death was assessed following preconditioning combined with subsequent total glucose deprivation, cell death was reduced in the cultures that had been preconditioned with 0.1 mM glucose for 30 minutes×3 days. CONCLUSIONS We found that that glucose reduction preconditioning protects hippocampal neurons against severe glucose deprivation-induced neuronal damage. This preconditioning was not associated with reductions in NMDAR-mediated cell death except when the preconditioning was combined with an additional exposure to a period of total glucose deprivation.
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β-Hydroxybutyrate supports synaptic vesicle cycling but reduces endocytosis and exocytosis in rat brain synaptosomes. Neurochem Int 2016; 93:73-81. [PMID: 26748385 DOI: 10.1016/j.neuint.2015.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/28/2015] [Accepted: 12/29/2015] [Indexed: 01/04/2023]
Abstract
The ketogenic diet is used as a prophylactic treatment for different types of brain diseases, such as epilepsy or Alzheimer's disease. In such a diet, carbohydrates are replaced by fats in everyday food, resulting in an elevation of blood-borne ketone bodies levels. Despite clinical applications of this treatment, the molecular mechanisms by which the ketogenic diet exerts its beneficial effects are still uncertain. In this study, we investigated the effect of replacing glucose by the ketone body β-hydroxybutyrate as the main energy substrate on synaptic vesicle recycling in rat brain synaptosomes. First, we observed that exposing presynaptic terminals to nonglycolytic energy substrates instead of glucose did not alter the plasma membrane potential. Next, we found that synaptosomes were able to maintain the synaptic vesicle cycle monitored with the fluorescent dye acridine orange when glucose was replaced by β-hydroxybutyrate. However, in presence of β-hydroxybutyrate, synaptic vesicle recycling was modified with reduced endocytosis. Replacing glucose by pyruvate also led to a reduced endocytosis. Addition of β-hydroxybutyrate to glucose-containing incubation medium was without effect. Reduced endocytosis in presence of β-hydroxybutyrate as sole energy substrate was confirmed using the fluorescent dye FM2-10. Also we found that replacement of glucose by ketone bodies leads to inhibition of exocytosis, monitored by FM2-10. However this reduction was smaller than the effect on endocytosis under the same conditions. Using both acridine orange in synaptosomes and the genetically encoded sensor synaptopHluorin in cortical neurons, we observed that replacing glucose by β-hydroxybutyrate did not modify the pH gradient of synaptic vesicles. In conclusion, the nonglycolytic energy substrates β-hydroxybutyrate and pyruvate are able to support synaptic vesicle recycling. However, they both reduce endocytosis. Reduction of both endocytosis and exocytosis together with misbalance between endocytosis and exocytosis could be involved in the anticonvulsant activity of the ketogenic diet.
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Influence of Glucose Deprivation on Membrane Potentials of Plasma Membranes, Mitochondria and Synaptic Vesicles in Rat Brain Synaptosomes. Neurochem Res 2015; 40:1188-96. [DOI: 10.1007/s11064-015-1579-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/02/2015] [Accepted: 04/08/2015] [Indexed: 12/26/2022]
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10
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Zhu J, Aja S, Kim EK, Park MJ, Ramamurthy S, Jia J, Hu X, Geng P, Ronnett GV. Physiological oxygen level is critical for modeling neuronal metabolism in vitro. J Neurosci Res 2011; 90:422-34. [PMID: 22002503 DOI: 10.1002/jnr.22765] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 06/29/2011] [Accepted: 07/16/2011] [Indexed: 11/09/2022]
Abstract
In vitro models are important tools for studying the mechanisms that govern neuronal responses to injury. Most neuronal culture methods employ nonphysiological conditions with regard to metabolic parameters. Standard neuronal cell culture is performed at ambient (21%) oxygen levels, whereas actual tissue oxygen levels in the mammalian brain range from 1% to 5%. In this study, we examined the consequences of oxygen level on the viability and metabolism of primary cultures of cortical neurons. Our results indicate that physiological oxygen level (5% O(2)) has a beneficial effect on cortical neuronal survival and mitochondrial function in vitro. Moreover, oxygen level affects metabolic fluxes: glucose uptake and glycolysis was enhanced at physiological oxygen level, whereas glucose oxidation and fatty acid oxidation were reduced. Adenosine monophosphate-activated protein kinase (AMPK) was more activated in 5% O(2) and appears to play a role in these metabolic effects. Inhibiting AMPK activity with compound C decreased glucose uptake, intracellular ATP level, and viability in neurons cultured in 5% O(2). These data indicate that oxygen level is an important parameter to consider when modeling neuronal responses to stress in vitro.
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Affiliation(s)
- Jing Zhu
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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11
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Robinet C, Pellerin L. Brain-derived neurotrophic factor enhances the expression of the monocarboxylate transporter 2 through translational activation in mouse cultured cortical neurons. J Cereb Blood Flow Metab 2010; 30:286-98. [PMID: 19794395 PMCID: PMC2949129 DOI: 10.1038/jcbfm.2009.208] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
MCT2 is the predominant neuronal monocarboxylate transporter allowing lactate use as an alternative energy substrate. It is suggested that MCT2 is upregulated to meet enhanced energy demands after modifications in synaptic transmission. Brain-derived neurotrophic factor (BDNF), a promoter of synaptic plasticity, significantly increased MCT2 protein expression in cultured cortical neurons (as shown by immunocytochemistry and western blot) through a translational regulation at the synaptic level. Brain-derived neurotrophic factor can cause translational activation through different signaling pathways. Western blot analyses showed that p44/p42 mitogen-activated protein kinase (MAPK), Akt, and S6 were strongly phosphorylated on BDNF treatment. To determine by which signal transduction pathway(s) BDNF mediates its upregulation of MCT2 protein expression, the effect of specific inhibitors for p38 MAPK, phosphoinositide 3-kinase (PI3K), mammalian target of rapamycin (mTOR), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK), p44/p42 MAPK (ERK), and Janus kinase 2 (JAK2) was evaluated. It could be observed that the BDNF-induced increase in MCT2 protein expression was almost completely blocked by all inhibitors, except for JAK2. These data indicate that BDNF induces an increase in neuronal MCT2 protein expression by a mechanism involving a concomitant stimulation of PI3K/Akt/mTOR/S6, p38 MAPK, and p44/p42 MAPK. Moreover, our observations suggest that changes in MCT2 expression could participate in the process of synaptic plasticity induced by BDNF.
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Affiliation(s)
- Camille Robinet
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
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12
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Glucose and lactate supply to the synapse. ACTA ACUST UNITED AC 2009; 63:149-59. [PMID: 19879896 DOI: 10.1016/j.brainresrev.2009.10.002] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/19/2009] [Accepted: 10/25/2009] [Indexed: 11/23/2022]
Abstract
The main source of energy for the mammalian brain is glucose, and the main sink of energy in the mammalian brain is the neuron, so the conventional view of brain energy metabolism is that glucose is consumed preferentially in neurons. But between glucose and the production of energy are several steps that do not necessarily take place in the same cell. An alternative model has been proposed that states that glucose preferentially taken by astrocytes, is degraded to lactate and then exported into neurons to be oxidized. Short of definitive data, opinions about the relative merits of these competing models are divided, making it a very exciting field of research. Furthermore, growing evidence suggests that lactate acts as a signaling molecule, involved in Na(+) sensing, glucosensing, and in coupling neuronal and glial activity to the modulation of vascular tone. In the present review, we discuss possible dynamics of glucose and lactate in excitatory synaptic regions, focusing on the transporters that catalyze the movement of these molecules.
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Ronnett GV, Ramamurthy S, Kleman AM, Landree LE, Aja S. AMPK in the brain: its roles in energy balance and neuroprotection. J Neurochem 2009; 109 Suppl 1:17-23. [PMID: 19393004 DOI: 10.1111/j.1471-4159.2009.05916.x] [Citation(s) in RCA: 232] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Adenosine monophosphate-activated protein kinase (AMPK) senses metabolic stress and integrates diverse physiological signals to restore energy balance. Multiple functions are indicated for AMPK in the CNS. While all neurons sense their own energy status, some integrate neuro-humoral signals to assess organismal energy balance. A variety of disease states may involve AMPK, so determining the underlying mechanisms is important. We review the impact of altered AMPK activity under physiological (hunger, satiety) and pathophysiological (stroke) conditions, as well as therapeutic manipulations of AMPK that may improve energy balance.
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Affiliation(s)
- Gabriele V Ronnett
- Department of Neuroscience, The Center for Metabolism and Obesity Research (CMOR), The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Fernando RN, Albiston AL, Chai SY. The insulin-regulated aminopeptidase IRAP is colocalised with GLUT4 in the mouse hippocampus - potential role in modulation of glucose uptake in neurones? Eur J Neurosci 2008; 28:588-98. [DOI: 10.1111/j.1460-9568.2008.06347.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Wilson GS, Johnson MA. In-vivo electrochemistry: what can we learn about living systems? Chem Rev 2008; 108:2462-81. [PMID: 18558752 DOI: 10.1021/cr068082i] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- George S Wilson
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
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Azarias G, Van de Ville D, Unser M, Chatton JY. Spontaneous NA+ transients in individual mitochondria of intact astrocytes. Glia 2008; 56:342-53. [PMID: 18098123 DOI: 10.1002/glia.20619] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mitochondria in intact cells maintain low Na(+) levels despite the large electrochemical gradient favoring cation influx into the matrix. In addition, they display individual spontaneous transient depolarizations. The authors report here that individual mitochondria in living astrocytes exhibit spontaneous increases in their Na(+) concentration (Na(mit)(+) spiking), as measured using the mitochondrial probe CoroNa Red. In a field of view with approximately 30 astrocytes, up to 1,400 transients per minute were typically detected under resting conditions. Na(mit)(+) spiking was also observed in neurons, but was scarce in two nonneural cell types tested. Astrocytic Na(mit)(+) spikes averaged 12.2 +/- 0.8 s in duration and 35.5 +/- 3.2 mM in amplitude and coincided with brief mitochondrial depolarizations; they were impaired by mitochondrial depolarization and ruthenium red pointing to the involvement of a cation uniporter. Na(mit)(+) spiking activity was significantly inhibited by mitochondrial Na(+)/H(+) exchanger inhibition and sensitive to cellular pH and Na(+) concentration. Ca(2+) played a permissive role on Na(mit)(+) spiking activity. Finally, the authors present evidence suggesting that Na(mit)(+) spiking frequency was correlated with cellular ATP levels. This study shows that, under physiological conditions, individual mitochondria in living astrocytes exhibit fast Na(+) exchange across their inner membrane, which reveals a new form of highly dynamic and localized functional regulation.
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17
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Ramírez BG, Rodrigues TB, Violante IR, Cruz F, Fonseca LL, Ballesteros P, Castro MMCA, García-Martín ML, Cerdán S. Kinetic properties of the redox switch/redox coupling mechanism as determined in primary cultures of cortical neurons and astrocytes from rat brain. J Neurosci Res 2008; 85:3244-53. [PMID: 17600826 DOI: 10.1002/jnr.21386] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We investigate the mechanisms underlying the redox switch/redox coupling hypothesis by characterizing the competitive consumption of glucose or lactate and the kinetics of pyruvate production in primary cultures of cortical neurons and astrocytes from rat brain. Glucose consumption was determined in neuronal cultures incubated in Krebs ringer bicarbonate buffer (KRB) containing 0.25-5 mM glucose, in the presence and absence of 5 mM lactate as an alternative substrate. Lactate consumption was measured in neuronal cultures incubated with 1-15 mM lactate, in the presence and absence of 1 mM glucose. In both cases, the alternative substrate increased the K(m) (mM) values for glucose consumption (from 2.2 +/- 0.2 to 3.6 +/- 0.1) or lactate consumption (from 7.8 +/- 0.1 to 8.5 +/- 0.1) without significant changes on the corresponding V(max). This is consistent with a competitive inhibition between the simultaneous consumption of glucose and lactate. When cultures of neurons or astrocytes were incubated with increasing lactate concentrations 1-20 mM, pyruvate production was observed with K(m) (mM) and V(max) (nmol/mg/h) values of 1.0 +/- 0.1 and 109 +/- 4 in neurons, or 0.28 +/- 0.1 and 342 +/- 54 in astrocytes. Thus, astrocytes or neurons are able to return to the incubation medium as pyruvate, a significant part of the lactate consumed. Present results support the reversible exchange of reducing equivalents between neurons and astrocytes in the form of lactate or pyruvate. Monocarboxylate exchange is envisioned to operate under near equilibrium, with the transcellular flux directed thermodynamically toward the more oxidized intracellular redox environment.
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Affiliation(s)
- Belén G Ramírez
- Laboratory for Imaging and Spectroscopy by Magnetic Resonance LISMAR, Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
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18
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Gavillet M, Allaman I, Magistretti PJ. Modulation of astrocytic metabolic phenotype by proinflammatory cytokines. Glia 2008; 56:975-89. [DOI: 10.1002/glia.20671] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Baker KD, Edwards TM. d-Lactate inhibition of memory in a single trial discrimination avoidance task in the young chick. Neurobiol Learn Mem 2007; 88:269-76. [PMID: 17692538 DOI: 10.1016/j.nlm.2007.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 06/17/2007] [Accepted: 06/19/2007] [Indexed: 11/26/2022]
Abstract
L-Lactate is a metabolite possibly able to meet some neuronal energy demands. However, a clear role for L-lactate in behaviour remains elusive. Administration of the inactive isomer D-lactate (1.75 mM; ic), immediately post-training, resulted in a persistent retention loss from 40 min post-training when used in conjuction with a single trial discrimination avoidance task designed for the young chick. Furthermore, 1mM noradrenaline (ic) administered 20 min post-training overcame the retention loss induced by D-lactate. Although not directly demonstrated in the current study, it is plausible that D-lactate inhibited memory processing by competing with L-lactate for uptake into neurons. The time of onset of the retention loss induced by D-lactate is in accord with findings where the action of noradrenaline is inhibited. The successful challenge of D-lactate inhibition by a high concentration of noradrenaline may suggest a relationship by some unidentified mechanism.
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Affiliation(s)
- K D Baker
- School of Psychology, Psychiatry and Psychological Medicine, Monash University, 3800 Vic., Australia
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Atlante A, de Bari L, Bobba A, Marra E, Passarella S. Transport and metabolism of L-lactate occur in mitochondria from cerebellar granule cells and are modified in cells undergoing low potassium dependent apoptosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1285-99. [PMID: 17950241 DOI: 10.1016/j.bbabio.2007.08.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 07/24/2007] [Accepted: 08/20/2007] [Indexed: 10/22/2022]
Abstract
Having confirmed that externally added L-lactate can enter cerebellar granule cells, we investigated whether and how L-lactate is metabolized by mitochondria from these cells under normal or apoptotic conditions. (1) L-lactate enters mitochondria, perhaps via an L-lactate/H+ symporter, and is oxidized in a manner stimulated by ADP. The existence of an L-lactate dehydrogenase, located in the inner mitochondrial compartment, was shown by immunological analysis. Neither the protein level nor the Km and Vmax values changed en route to apoptosis. (2) In both normal and apoptotic cell homogenates, externally added L-lactate caused reduction of the intramitochondrial pyridine cofactors, inhibited by phenylsuccinate. This process mirrored L-lactate uptake by mitochondria and occurred with a hyperbolic dependence on L-lactate concentrations. Pyruvate appeared outside mitochondria as a result of external addition of L-lactate. The rate of the process depended on L-lactate concentration and showed saturation characteristics. This shows the occurrence of an intracellular L-lactate/pyruvate shuttle, whose activity was limited by the putative L-lactate/pyruvate antiporter. Both the carriers were different from the monocarboxylate carrier. (3) L-lactate transport changed en route to apoptosis. Uptake increased in the early phase of apoptosis, but decreased in the late phase with characteristics of a non-competitive like inhibition. In contrast, the putative L-lactate/pyruvate antiport decreased en route to apoptosis with characteristics of a competitive like inhibition in early apoptosis, and a mixed non-competitive like inhibition in late apoptosis.
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Affiliation(s)
- Anna Atlante
- Istituto di Biomembrane e Bioenergetica, Consiglio Nazionale delle Ricerche, Via G Amendola, 165/A-70126, Bari, Italy.
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Physiological glucose is critical for optimized neuronal viability and AMPK responsiveness in vitro. J Neurosci Methods 2007; 167:292-301. [PMID: 17936912 DOI: 10.1016/j.jneumeth.2007.08.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Revised: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 02/04/2023]
Abstract
Understanding the mechanisms that govern neuronal responses to oxidative and metabolic stress is essential for therapeutic intervention. In vitro modeling is an important approach for these studies, as the metabolic environment influences neuronal responses. Surprisingly, most neuronal culture methods employ conditions that are non-physiological, especially with regards to glucose concentrations, which often exceed 20mM. This concentration is a significant departure from physiological glucose levels, and even several-fold greater than that seen during severe hyperglycemia. The goal of this study was to establish a physiological neuronal culture system that will facilitate the study of neuronal energy metabolism and responses to metabolic stress. We demonstrate that the metabolic environment during preparation, plating, and maintenance of cultures affects neuronal viability and the response of neuronal pathways to changes in energy balance.
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Pellerin L, Bouzier-Sore AK, Aubert A, Serres S, Merle M, Costalat R, Magistretti PJ. Activity-dependent regulation of energy metabolism by astrocytes: An update. Glia 2007; 55:1251-1262. [PMID: 17659524 DOI: 10.1002/glia.20528] [Citation(s) in RCA: 601] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Astrocytes play a critical role in the regulation of brain metabolic responses to activity. One detailed mechanism proposed to describe the role of astrocytes in some of these responses has come to be known as the astrocyte-neuron lactate shuttle hypothesis (ANLSH). Although controversial, the original concept of a coupling mechanism between neuronal activity and glucose utilization that involves an activation of aerobic glycolysis in astrocytes and lactate consumption by neurons provides a heuristically valid framework for experimental studies. In this context, it is necessary to provide a survey of recent developments and data pertaining to this model. Thus, here, we review very recent experimental evidence as well as theoretical arguments strongly supporting the original model and in some cases extending it. Aspects revisited include the existence of glutamate-induced glycolysis in astrocytes in vitro, ex vivo, and in vivo, lactate as a preferential oxidative substrate for neurons, and the notion of net lactate transfer between astrocytes and neurons in vivo. Inclusion of a role for glycogen in the ANLSH is discussed in the light of a possible extension of the astrocyte-neuron lactate shuttle (ANLS) concept rather than as a competing hypothesis. New perspectives offered by the application of this concept include a better understanding of the basis of signals used in functional brain imaging, a role for neuron-glia metabolic interactions in glucose sensing and diabetes, as well as novel strategies to develop therapies against neurodegenerative diseases based upon improving astrocyte-neuron coupled energetics.
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Affiliation(s)
- Luc Pellerin
- Département de Physiologie, Université de Lausanne, Switzerland
| | - Anne-Karine Bouzier-Sore
- Unité de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS-Université Victor Segalen, Bordeaux, France
| | - Agnès Aubert
- Département de Physiologie, Université de Lausanne, Switzerland
| | - Sébastien Serres
- Unité de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS-Université Victor Segalen, Bordeaux, France
| | - Michel Merle
- Unité de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS-Université Victor Segalen, Bordeaux, France
| | - Robert Costalat
- INSERM U678, Université Pierre et Marie Curie-Paris 6, Paris, France
| | - Pierre J Magistretti
- Brain and Mind Institute, Ecole Polytechnique Fédérale de Lausanne and Centre de Neurosciences Psychiatriques, Hôpital de Cery, Prilly, Switzerland
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