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Rothman DL, Behar KL, Dienel GA. Mechanistic stoichiometric relationship between the rates of neurotransmission and neuronal glucose oxidation: Reevaluation of and alternatives to the pseudo-malate-aspartate shuttle model. J Neurochem 2024; 168:555-591. [PMID: 36089566 DOI: 10.1111/jnc.15619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/08/2022] [Accepted: 04/15/2022] [Indexed: 11/26/2022]
Abstract
The ~1:1 stoichiometry between the rates of neuronal glucose oxidation (CMRglc-ox-N) and glutamate (Glu)/γ-aminobutyric acid (GABA)-glutamine (Gln) neurotransmitter (NT) cycling between neurons and astrocytes (VNTcycle) has been firmly established. However, the mechanistic basis for this relationship is not fully understood, and this knowledge is critical for the interpretation of metabolic and brain imaging studies in normal and diseased brain. The pseudo-malate-aspartate shuttle (pseudo-MAS) model established the requirement for glycolytic metabolism in cultured glutamatergic neurons to produce NADH that is shuttled into mitochondria to support conversion of extracellular Gln (i.e., astrocyte-derived Gln in vivo) into vesicular neurotransmitter Glu. The evaluation of this model revealed that it could explain half of the 1:1 stoichiometry and it has limitations. Modifications of the pseudo-MAS model were, therefore, devised to address major knowledge gaps, that is, submitochondrial glutaminase location, identities of mitochondrial carriers for Gln and other model components, alternative mechanisms to transaminate α-ketoglutarate to form Glu and shuttle glutamine-derived ammonia while maintaining mass balance. All modified models had a similar 0.5 to 1.0 predicted mechanistic stoichiometry between VNTcycle and the rate of glucose oxidation. Based on studies of brain β-hydroxybutyrate oxidation, about half of CMRglc-ox-N may be linked to glutamatergic neurotransmission and localized in pre-synaptic structures that use pseudo-MAS type mechanisms for Glu-Gln cycling. In contrast, neuronal compartments that do not participate in transmitter cycling may use the MAS to sustain glucose oxidation. The evaluation of subcellular compartmentation of neuronal glucose metabolism in vivo is a critically important topic for future studies to understand glutamatergic and GABAergic neurotransmission.
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Affiliation(s)
- Douglas L Rothman
- Magnetic Resonance Research Center and Departments of Radiology and Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Kevin L Behar
- Magnetic Resonance Research Center and Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
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2
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Khodaie B, Edelmann E, Leßmann V. Distinct GABAergic modulation of timing-dependent LTP in CA1 pyramidal neurons along the longitudinal axis of the mouse hippocampus. iScience 2024; 27:109320. [PMID: 38487018 PMCID: PMC10937841 DOI: 10.1016/j.isci.2024.109320] [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: 04/07/2023] [Revised: 01/25/2024] [Accepted: 02/20/2024] [Indexed: 03/17/2024] Open
Abstract
Synaptic plasticity in the hippocampus underlies episodic memory formation, with dorsal hippocampus being instrumental for spatial memory whereas ventral hippocampus is crucial for emotional learning. Here, we studied how GABAergic inhibition regulates physiologically relevant low repeat spike timing-dependent LTP (t-LTP) at Schaffer collateral-CA1 synapses along the dorsoventral hippocampal axis. We used two t-LTP protocols relying on only 6 repeats of paired spike-firing in pre- and postsynaptic cells within 10 s that differ in postsynaptic firing patterns. GABAA receptor mechanisms played a greater role in blocking 6× 1:1 t-LTP that recruits single postsynaptic action potentials. 6× 1:4 t-LTP that depends on postsynaptic burst-firing unexpectedly required intact GABAB receptor signaling. The magnitude of both t-LTP-forms decreased along the dorsoventral axis, despite increasing excitability and basal synaptic strength in this direction. This suggests that GABAergic inhibition contributes to the distinct roles of dorsal and ventral hippocampus in memory formation.
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Affiliation(s)
- Babak Khodaie
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
| | - Elke Edelmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences, 39104 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
| | - Volkmar Leßmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences, 39104 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
- DZPG (German Center of Mental Health), partner site Halle/Jena/Magdeburg (CIRC), Magdeburg, Germany
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3
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Zhang D, Hua Z, Li Z. The role of glutamate and glutamine metabolism and related transporters in nerve cells. CNS Neurosci Ther 2024; 30:e14617. [PMID: 38358002 PMCID: PMC10867874 DOI: 10.1111/cns.14617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/16/2024] Open
Abstract
BACKGROUND Glutamate and glutamine are the most abundant amino acids in the blood and play a crucial role in cell survival in the nervous system. Various transporters found in cell and mitochondrial membranes, such as the solute carriers (SLCs) superfamily, are responsible for maintaining the balance of glutamate and glutamine in the synaptic cleft and within cells. This balance affects the metabolism of glutamate and glutamine as non-essential amino acids. AIMS This review aims to provide an overview of the transporters and enzymes associated with glutamate and glutamine in neuronal cells. DISCUSSION We delve into the function of glutamate and glutamine in the nervous system by discussing the transporters involved in the glutamate-glutamine cycle and the key enzymes responsible for their mutual conversion. Additionally, we highlight the role of glutamate and glutamine as carbon and nitrogen donors, as well as their significance as precursors for the synthesis of reduced glutathione (GSH). CONCLUSION Glutamate and glutamine play a crucial role in the brain due to their special effects. It is essential to focus on understanding glutamate and glutamine metabolism to comprehend the physiological behavior of nerve cells and to treat nervous system disorders and cancer.
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Affiliation(s)
- Dongyang Zhang
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
| | - Zhongyan Hua
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
| | - Zhijie Li
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
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4
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Zhang YM, Qi YB, Gao YN, Chen WG, Zhou T, Zang Y, Li J. Astrocyte metabolism and signaling pathways in the CNS. Front Neurosci 2023; 17:1217451. [PMID: 37732313 PMCID: PMC10507181 DOI: 10.3389/fnins.2023.1217451] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/18/2023] [Indexed: 09/22/2023] Open
Abstract
Astrocytes comprise half of the cells in the central nervous system and play a critical role in maintaining metabolic homeostasis. Metabolic dysfunction in astrocytes has been indicated as the primary cause of neurological diseases, such as depression, Alzheimer's disease, and epilepsy. Although the metabolic functionalities of astrocytes are well known, their relationship to neurological disorders is poorly understood. The ways in which astrocytes regulate the metabolism of glucose, amino acids, and lipids have all been implicated in neurological diseases. Metabolism in astrocytes has also exhibited a significant influence on neuron functionality and the brain's neuro-network. In this review, we focused on metabolic processes present in astrocytes, most notably the glucose metabolic pathway, the fatty acid metabolic pathway, and the amino-acid metabolic pathway. For glucose metabolism, we focused on the glycolysis pathway, pentose-phosphate pathway, and oxidative phosphorylation pathway. In fatty acid metabolism, we followed fatty acid oxidation, ketone body metabolism, and sphingolipid metabolism. For amino acid metabolism, we summarized neurotransmitter metabolism and the serine and kynurenine metabolic pathways. This review will provide an overview of functional changes in astrocyte metabolism and provide an overall perspective of current treatment and therapy for neurological disorders.
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Affiliation(s)
- Yong-mei Zhang
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ying-bei Qi
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ya-nan Gao
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Institute of Pharmaceutical Sciences, China Pharmaceutical University, Nanjing, Jiangsu, China
| | - Wen-gang Chen
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Institute of Pharmaceutical Sciences, China Pharmaceutical University, Nanjing, Jiangsu, China
| | - Ting Zhou
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yi Zang
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jia Li
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- Institute of Pharmaceutical Sciences, China Pharmaceutical University, Nanjing, Jiangsu, China
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5
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Andersen JV, Schousboe A. Glial Glutamine Homeostasis in Health and Disease. Neurochem Res 2023; 48:1100-1128. [PMID: 36322369 DOI: 10.1007/s11064-022-03771-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 08/25/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
Glutamine is an essential cerebral metabolite. Several critical brain processes are directly linked to glutamine, including ammonia homeostasis, energy metabolism and neurotransmitter recycling. Astrocytes synthesize and release large quantities of glutamine, which is taken up by neurons to replenish the glutamate and GABA neurotransmitter pools. Astrocyte glutamine hereby sustains the glutamate/GABA-glutamine cycle, synaptic transmission and general brain function. Cerebral glutamine homeostasis is linked to the metabolic coupling of neurons and astrocytes, and relies on multiple cellular processes, including TCA cycle function, synaptic transmission and neurotransmitter uptake. Dysregulations of processes related to glutamine homeostasis are associated with several neurological diseases and may mediate excitotoxicity and neurodegeneration. In particular, diminished astrocyte glutamine synthesis is a common neuropathological component, depriving neurons of an essential metabolic substrate and precursor for neurotransmitter synthesis, hereby leading to synaptic dysfunction. While astrocyte glutamine synthesis is quantitatively dominant in the brain, oligodendrocyte-derived glutamine may serve important functions in white matter structures. In this review, the crucial roles of glial glutamine homeostasis in the healthy and diseased brain are discussed. First, we provide an overview of cellular recycling, transport, synthesis and metabolism of glutamine in the brain. These cellular aspects are subsequently discussed in relation to pathological glutamine homeostasis of hepatic encephalopathy, epilepsy, Alzheimer's disease, Huntington's disease and amyotrophic lateral sclerosis. Further studies on the multifaceted roles of cerebral glutamine will not only increase our understanding of the metabolic collaboration between brain cells, but may also aid to reveal much needed therapeutic targets of several neurological pathologies.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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6
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Stevens HE, Scuderi S, Collica SC, Tomasi S, Horvath TL, Vaccarino FM. Neonatal loss of FGFR2 in astroglial cells affects locomotion, sociability, working memory, and glia-neuron interactions in mice. Transl Psychiatry 2023; 13:89. [PMID: 36906620 PMCID: PMC10008554 DOI: 10.1038/s41398-023-02372-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 03/13/2023] Open
Abstract
Fibroblast growth factor receptor 2 (FGFR2) is almost exclusively expressed in glial cells in postnatal mouse brain, but its impact in glia for brain behavioral functioning is poorly understood. We compared behavioral effects from FGFR2 loss in both neurons and astroglial cells and from FGFR2 loss in astroglial cells by using either the pluripotent progenitor-driven hGFAP-cre or the tamoxifen-inducible astrocyte-driven GFAP-creERT2 in Fgfr2 floxed mice. When FGFR2 was eliminated in embryonic pluripotent precursors or in early postnatal astroglia, mice were hyperactive, and had small changes in working memory, sociability, and anxiety-like behavior. In contrast, FGFR2 loss in astrocytes starting at 8 weeks of age resulted only in reduced anxiety-like behavior. Therefore, early postnatal loss of FGFR2 in astroglia is critical for broad behavioral dysregulation. Neurobiological assessments demonstrated that astrocyte-neuron membrane contact was reduced and glial glutamine synthetase expression increased only by early postnatal FGFR2 loss. We conclude that altered astroglial cell function dependent on FGFR2 in the early postnatal period may result in impaired synaptic development and behavioral regulation, modeling childhood behavioral deficits like attention deficit hyperactivity disorder (ADHD).
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Affiliation(s)
- Hanna E Stevens
- Child Study Center, Yale School of Medicine, New Haven, CT, 06520, USA.
- Department of Psychiatry, Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA, 52246, USA.
| | - Soraya Scuderi
- Child Study Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Sarah C Collica
- Child Study Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Simone Tomasi
- Child Study Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Tamas L Horvath
- Department of Neuroscience, Yale University, New Haven, CT, 06520, USA
- Department of Comparative Medicine, Department of Obstetrics and Gynecology, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Flora M Vaccarino
- Child Study Center, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Neuroscience, Yale University, New Haven, CT, 06520, USA
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7
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Liang SL, Liao WL, Chen RS. Perinatal blockade of neuronal glutamine transport sex-differentially alters glutamatergic synaptic transmission and organization of neurons in the ventrolateral ventral media hypothalamus of adult rats. J Neuroendocrinol 2023; 35:e13253. [PMID: 36949648 DOI: 10.1111/jne.13253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 02/13/2023] [Accepted: 02/28/2023] [Indexed: 03/16/2023]
Abstract
Compared to male pups, perinatal female rats rely heavily on neuronal glutamine (Gln) transport for sustaining glutamatergic synaptic release in neurons of the ventrolateral ventral media nucleus of the hypothalamus (vlVMH). VMH mainly regulates female sexual behavior and increases glutamate release of perinatal hypothalamic neurons, permanently enhances dendrite spine numbers and is associated with brain and behavioral defeminization. We hypothesized that perinatal interruption of neuronal Gln transport may alter the glutamatergic synaptic transmission during adulthood. Perinatal rats of both sexes received an intracerebroventricular injection of a neuronal Gln uptake blocker, alpha-(methylamino) isobutyric acid (MeAIB, 5 mM), and were raised until adulthood. Whole-cell voltage-clamp recordings of miniature excitatory postsynaptic currents (mEPSCs) and evoked EPSCs (eEPSCs) of vlVMH neurons in adult rats with the perinatal pretreatment were conducted and neuron morphology was subjected to post hoc examination. Perinatal MeAIB treatment sex-differentially increased mEPSC frequency in males, but decreased mEPSC amplitude and synaptic Glu release in females. The pretreatment sex-differentially decreased eEPSC amplitude in males but increased AMPA/NMDA current ratio in females, and changed the morphology of vlVMH neurons of adult rats to that of the opposite sex. Most alterations in the glutamatergic synaptic transmission resembled the changes occurring during MeAIB acute exposure in perinatal rats of both sexes. We conclude that perinatal blockade of neuronal Gln transport mediates changes via different presynaptic and postsynaptic mechanisms to induce sex-differential alterations of the glutamatergic synaptic transmission and organization of vlVMH neurons in adult rats. These changes may be permanent and associated with brain and behavior feminization and/or defeminization in rats.
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Affiliation(s)
- Shu-Ling Liang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
| | - Wen-Lin Liao
- Institute of Neuroscience, National Chengchi University, Taipei, Taiwan
| | - Rou-Shayn Chen
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- Division of Movement Disorders, Department of Neurology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
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8
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Astrocytes regulate inhibitory neurotransmission through GABA uptake, metabolism, and recycling. Essays Biochem 2023; 67:77-91. [PMID: 36806927 DOI: 10.1042/ebc20220208] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 02/23/2023]
Abstract
Synaptic regulation of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) is essential for brain function. Cerebral GABA homeostasis is tightly regulated through multiple mechanisms and is directly coupled to the metabolic collaboration between neurons and astrocytes. In this essay, we outline and discuss the fundamental roles of astrocytes in regulating synaptic GABA signaling. A major fraction of synaptic GABA is removed from the synapse by astrocytic uptake. Astrocytes utilize GABA as a metabolic substrate to support glutamine synthesis. The astrocyte-derived glutamine is subsequently transferred to neurons where it serves as the primary precursor of neuronal GABA synthesis. The flow of GABA and glutamine between neurons and astrocytes is collectively termed the GABA-glutamine cycle and is essential to sustain GABA synthesis and inhibitory signaling. In certain brain areas, astrocytes are even capable of synthesizing and releasing GABA to modulate inhibitory transmission. The majority of oxidative GABA metabolism in the brain takes place in astrocytes, which also leads to synthesis of the GABA-related metabolite γ-hydroxybutyric acid (GHB). The physiological roles of endogenous GHB remain unclear, but may be related to regulation of tonic inhibition and synaptic plasticity. Disrupted inhibitory signaling and dysfunctional astrocyte GABA handling are implicated in several diseases including epilepsy and Alzheimer's disease. Synaptic GABA homeostasis is under astrocytic control and astrocyte GABA uptake, metabolism, and recycling may therefore serve as relevant targets to ameliorate pathological inhibitory signaling.
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9
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Mosleh M, Javan M, Fathollahi Y. The properties of long-term potentiation at SC-CA1/ TA-CA1 hippocampal synaptic pathways depends upon their input pathway activation patterns. IBRO Neurosci Rep 2023; 14:358-365. [PMID: 37020855 PMCID: PMC10067737 DOI: 10.1016/j.ibneur.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/25/2023] [Indexed: 03/30/2023] Open
Abstract
Long-term potentiation (LTP) has been considered as a cellular mechanism of memory. Since the Schaffer collateral (SC) and temporoammonic (TA) inputs to CA1 are distinct synaptic pathways that could mediate different cognitive functions, this study was therefore aimed to separately study and compare the properties of LTP of these two synaptic pathways. In the current study we used slice electrophysiological methods to compare various properties of these two synaptic pathways in response to single, paired pulse stimulation, and to three standard protocols for inducing LTP: the high frequency electrical stimulation (HFS), theta-burst (TBS), and primed burst (PBs) stimulation. We found that the SC-CA1 synapses could produce bigger maximum synaptic responses than TA-CA1 synapses. In addition, we showed that paired-pulse ratios of the SC-CA1 synapses were higher than TA-CA1 synapses at certain inter-pulses intervals. Finally, we showed a higher LTP% was induced by PBs or TBS at the SC-CA1 synapse than the TA-CA1 synapse. Briefly, our findings suggest the differential basal synaptic transmission, paired-pulse evoked synaptic responses, and LTP exhibition of the hippocampal SC-CA1/ TA-CA1 synaptic pathways, which may rely on spontaneous and evoked activity pattern at the local circuit level.
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10
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Andersen JV, Schousboe A, Verkhratsky A. Astrocyte energy and neurotransmitter metabolism in Alzheimer's disease: integration of the glutamate/GABA-glutamine cycle. Prog Neurobiol 2022; 217:102331. [PMID: 35872221 DOI: 10.1016/j.pneurobio.2022.102331] [Citation(s) in RCA: 64] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 02/06/2023]
Abstract
Astrocytes contribute to the complex cellular pathology of Alzheimer's disease (AD). Neurons and astrocytes function in close collaboration through neurotransmitter recycling, collectively known as the glutamate/GABA-glutamine cycle, which is essential to sustain neurotransmission. Neurotransmitter recycling is intimately linked to astrocyte energy metabolism. In the course of AD, astrocytes undergo extensive metabolic remodeling, which may profoundly affect the glutamate/GABA-glutamine cycle. The consequences of altered astrocyte function and metabolism in relation to neurotransmitter recycling are yet to be comprehended. Metabolic alterations of astrocytes in AD deprive neurons of metabolic support, thereby contributing to synaptic dysfunction and neurodegeneration. In addition, several astrocyte-specific components of the glutamate/GABA-glutamine cycle, including glutamine synthesis and synaptic neurotransmitter uptake, are perturbed in AD. Integration of the complex astrocyte biology within the context of AD is essential for understanding the fundamental mechanisms of the disease, while restoring astrocyte metabolism may serve as an approach to arrest or even revert clinical progression of AD.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, 48011 Bilbao, Spain; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania.
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11
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Zielińska M, Albrecht J, Popek M. Dysregulation of Astrocytic Glutamine Transport in Acute Hyperammonemic Brain Edema. Front Neurosci 2022; 16:874750. [PMID: 35733937 PMCID: PMC9207324 DOI: 10.3389/fnins.2022.874750] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Acute liver failure (ALF) impairs ammonia clearance from blood, which gives rise to acute hyperammonemia and increased ammonia accumulation in the brain. Since in brain glutamine synthesis is the only route of ammonia detoxification, hyperammonemia is as a rule associated with increased brain glutamine content (glutaminosis) which correlates with and contributes along with ammonia itself to hyperammonemic brain edema-associated with ALF. This review focuses on the effects of hyperammonemia on the two glutamine carriers located in the astrocytic membrane: Slc38a3 (SN1, SNAT3) and Slc7a6 (y + LAT2). We emphasize the contribution of the dysfunction of either of the two carriers to glutaminosis- related aspects of brain edema: retention of osmotically obligated water (Slc38a3) and induction of oxidative/nitrosative stress (Slc7a6). The changes in glutamine transport link glutaminosis- evoked mitochondrial dysfunction to oxidative-nitrosative stress as formulated in the “Trojan Horse” hypothesis.
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12
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Pardo B, Herrada-Soler E, Satrústegui J, Contreras L, del Arco A. AGC1 Deficiency: Pathology and Molecular and Cellular Mechanisms of the Disease. Int J Mol Sci 2022; 23:528. [PMID: 35008954 PMCID: PMC8745132 DOI: 10.3390/ijms23010528] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 02/01/2023] Open
Abstract
AGC1/Aralar/Slc25a12 is the mitochondrial carrier of aspartate-glutamate, the regulatory component of the NADH malate-aspartate shuttle (MAS) that transfers cytosolic redox power to neuronal mitochondria. The deficiency in AGC1/Aralar leads to the human rare disease named "early infantile epileptic encephalopathy 39" (EIEE 39, OMIM # 612949) characterized by epilepsy, hypotonia, arrested psychomotor neurodevelopment, hypo myelination and a drastic drop in brain aspartate (Asp) and N-acetylaspartate (NAA). Current evidence suggest that neurons are the main brain cell type expressing Aralar. However, paradoxically, glial functions such as myelin and Glutamine (Gln) synthesis are markedly impaired in AGC1 deficiency. Herein, we discuss the role of the AGC1/Aralar-MAS pathway in neuronal functions such as Asp and NAA synthesis, lactate use, respiration on glucose, glutamate (Glu) oxidation and other neurometabolic aspects. The possible mechanism triggering the pathophysiological findings in AGC1 deficiency, such as epilepsy and postnatal hypomyelination observed in humans and mice, are also included. Many of these mechanisms arise from findings in the aralar-KO mice model that extensively recapitulate the human disease including the astroglial failure to synthesize Gln and the dopamine (DA) mishandling in the nigrostriatal system. Epilepsy and DA mishandling are a direct consequence of the metabolic defect in neurons due to AGC1/Aralar deficiency. However, the deficits in myelin and Gln synthesis may be a consequence of neuronal affectation or a direct effect of AGC1/Aralar deficiency in glial cells. Further research is needed to clarify this question and delineate the transcellular metabolic fluxes that control brain functions. Finally, we discuss therapeutic approaches successfully used in AGC1-deficient patients and mice.
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Affiliation(s)
- Beatriz Pardo
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Eduardo Herrada-Soler
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Jorgina Satrústegui
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Laura Contreras
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.H.-S.); (J.S.); (L.C.)
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Araceli del Arco
- Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain;
- Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro Regional de Investigaciones Biomédicas, Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla La Mancha, 45071 Toledo, Spain
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13
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Liang SL, Tong YS, Hwang LL, Huang YZ, Chen CY. CART Peptides Differently Regulate Firing Rates and GABAergic Synaptic Inputs of DMV Neurons Innervating the Stomach Antrum and Cecum of Adult Male Rats. Neuroendocrinology 2022; 112:555-570. [PMID: 34348334 DOI: 10.1159/000518690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 07/23/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIM Central administration of cocaine- and amphetamine-regulated transcript peptides (CARTp) alters gastrointestinal motility and reduces food intake in rats. Since neurons in the dorsal motor nucleus of the vagus (DMV) receive GABAergic and glutamatergic inputs and innervate the smooth muscle of gastrointestinal organs, we hypothesized that CARTp acts on the DMV or presynaptic neurons. METHODS We used 3,3'-dioctadecyloxa-carbocyanine perchlorate (DiO) retrograde tracing with electrophysiological methods to record DMV neurons innervating the stomach antrum or cecum in brainstem slices from adult rats. RESULTS DiO application did not change the electrophysiological properties of DMV neurons. CART55-102 had no effect on the basal firing rates of neurons in either the stomach antrum-labeled group (SLG) or cecum-labeled group (CLG). When presynaptic inputs were blocked, CART55-102 further increased the firing rates of the SLG, suggesting a direct excitatory effect. Spontaneous inhibitory postsynaptic currents (sIPSCs) occurred at a higher frequency in SLG neurons than in CLG neurons. CART55-102 reduced the amplitude and the frequency of sIPSCs in SLG neurons dose-dependently, with higher doses also reducing spontaneous excitatory postsynaptic currents (sEPSCs). Higher doses of CART55-102 reduced sIPSC and sEPSC amplitudes in CLG neurons, suggesting a postsynaptic effect. In response to incremental current injections, the SLG neurons exhibited less increases in firing activity. Simultaneous applications of current injections and CART55-102 decreased the firing activity of the CLG. Therefore, stomach antrum-projecting DMV neurons possess a higher gating ability to stabilize firing activity. CONCLUSION The mechanism by which CARTp mediates anorectic actions may be through a direct reduction in cecum-projecting DMV neuron excitability and, to a lesser extent, that of antrum-projecting DMV neurons, by acting on receptors of these neurons.
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Affiliation(s)
- Shu-Ling Liang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
| | - Yong-Sheng Tong
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ling-Ling Hwang
- Department of Physiology, Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ying-Zu Huang
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
- Department of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Yen Chen
- Division of Gastroenterology and Hepatology, Taipei Veterans General Hospital, Faculty of Medicine, Institute of Emergency and Critical Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
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14
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Haim LB, Schirmer L, Zulji A, Sabeur K, Tiret B, Ribon M, Chang S, Lamers WH, BoillEée S, Chaumeil MM, Rowitch DH. Evidence for glutamine synthetase function in mouse spinal cord oligodendrocytes. Glia 2021; 69:2812-2827. [PMID: 34396578 PMCID: PMC8502205 DOI: 10.1002/glia.24071] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 07/02/2021] [Accepted: 07/29/2021] [Indexed: 11/07/2022]
Abstract
Glutamine synthetase (GS) is a key enzyme that metabolizes glutamate into glutamine. While GS is highly enriched in astrocytes, expression in other glial lineages has been noted. Using a combination of reporter mice and cell type-specific markers, we show that GS is expressed in myelinating oligodendrocytes (OL) but not oligodendrocyte progenitor cells of the mouse and human ventral spinal cord. To investigate the role of GS in mature OL, we used a conditional knockout (cKO) approach to selectively delete GS-encoding gene (Glul) in OL, which caused a significant decrease in glutamine levels on mouse spinal cord extracts. GS cKO mice (CNP-cre+ :Glulfl/fl ) showed no differences in motor neuron numbers, size or axon density; OL differentiation and myelination in the ventral spinal cord was normal up to 6 months of age. Interestingly, GS cKO mice showed a transient and specific decrease in peak force while locomotion and motor coordination remained unaffected. Last, GS expression in OL was increased in chronic pathological conditions in both mouse and humans. We found a disease-stage dependent increase of OL expressing GS in the ventral spinal cord of SOD1(G93A) mouse model of amyotrophic lateral sclerosis. Moreover, we showed that GLUL transcripts levels were increased in OL in leukocortical tissue from multiple sclerosis but not control patients. These findings provide evidence towards OL-encoded GS function in spinal cord sensorimotor axis, which is dysregulated in chronic neurological diseases.
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Affiliation(s)
- Lucile Ben Haim
- Department of Pediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Lucas Schirmer
- Department of Pediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
- Department of Neurology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Amel Zulji
- Department of Neurology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Khalida Sabeur
- Department of Pediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Brice Tiret
- Departments of Physical Therapy and Rehabilitation Science and of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Matthieu Ribon
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Sandra Chang
- Department of Pediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Wouter H. Lamers
- Tytgat Institute for Liver and Intestinal Research, Amsterdam University Medical Centers, Meibergdreef 15, 1105 BK Amsterdam, The Netherlands
| | - Séverine BoillEée
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Myriam M. Chaumeil
- Departments of Physical Therapy and Rehabilitation Science and of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - David H. Rowitch
- Department of Pediatrics, Wellcome - MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Departments of Pediatrics and Neurosurgery, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
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15
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Taspinar N, Hacimuftuoglu A, Butuner S, Togar B, Arslan G, Taghizadehghalehjoughi A, Okkay U, Agar E, Stephens R, Turkez H, Abd El-Aty AM. Differential effects of inhibitors of PTZ-induced kindling on glutamate transporters and enzyme expression. Clin Exp Pharmacol Physiol 2021; 48:1662-1673. [PMID: 34409650 DOI: 10.1111/1440-1681.13575] [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: 12/22/2020] [Revised: 07/31/2021] [Accepted: 08/14/2021] [Indexed: 12/01/2022]
Abstract
Epilepsy is a neurological disorder resulting from abnormal neuronal firing in the brain. Glutamate transporters and the glutamate-glutamine cycle play crucial roles in the development of seizures. In the present study, the correlation of epilepsy with glutamate transporters and enzymes was investigated. Herein, male Wistar rats were randomly allocated into four groups (six animals/group); 35 mg/kg pentylenetetrazole (PTZ) was used to induce a kindling model of epilepsy. Once the kindling model was established, animals were treated for 15 days with either valproic acid (VPA, 350 mg/kg) or ceftriaxone (CEF, 200 mg/kg) in addition to the control group receiving saline. After treatment, electrocorticography (ECoG) was performed to record the electrical activity of the cerebral cortex. The glutamate reuptake time (T80 ) was also determined in situ using an in vivo voltammetry. The expression levels of glutamate transporters and enzymes in the M1 and CA3 areas of the brain were determined using a real-time polymerase chain reaction (RT-PCR). ECoG measurements showed that the mean spike number of the PTZ + VPA and PTZ + CEF groups was significantly lower (p < 0.05) than that of the PTZ group. Compared with the PTZ group, VPA or CEF treatment decreased the glutamate reuptake time (T80 ). The expression levels of EAAC1, GLT-1, GLAST, glutamine synthetase (GS), and glutaminase were increased in the PTZ group. Treatment with VPA or CEF enhanced the expression levels of GLT-1, GLAST, EAAC1, and GS, whereas the glutaminase expression level was reduced. The current results suggest that VPA or CEF decreases seizure activity by increasing glutamate reuptake by upregulating GLT-1 and GLAST expression, implying a possible mechanism for treating epilepsy. Also, we have suggested a novel mechanism for the antiepileptic activity of VPA via decreasing glutaminase expression levels. To our knowledge, this is the first study to measure the glutamate reuptake time in situ during the seizure (i.e., real-time measurement).
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Affiliation(s)
- Numan Taspinar
- Department of Medical Pharmacology, Faculty of Medicine, Uşak University, Uşak, Turkey
| | - Ahmet Hacimuftuoglu
- Department of Medical Pharmacology, Faculty of Medicine, Atatürk University, Erzurum, Turkey
| | - Selcuk Butuner
- Department of Medical Pharmacology, Faculty of Medicine, Atatürk University, Erzurum, Turkey
| | - Basak Togar
- Department of Medical Services and Techniques, Vocational School of Health Services, Bayburt University, Bayburt, Turkey
| | - Gokhan Arslan
- Department of Physiology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Ali Taghizadehghalehjoughi
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Atatürk University, Erzurum, Turkey
| | - Ufuk Okkay
- Department of Medical Pharmacology, Faculty of Medicine, Atatürk University, Erzurum, Turkey
| | - Erdal Agar
- Department of Physiology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Robert Stephens
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Hasan Turkez
- Department of Medical Biology, Faculty of Medicine, Atatürk University, Erzurum, Turkey
| | - A M Abd El-Aty
- Department of Medical Pharmacology, Faculty of Medicine, Atatürk University, Erzurum, Turkey
- Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
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16
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Wilson CS, Dohare P, Orbeta S, Nalwalk JW, Huang Y, Ferland RJ, Sah R, Scimemi A, Mongin AA. Late adolescence mortality in mice with brain-specific deletion of the volume-regulated anion channel subunit LRRC8A. FASEB J 2021; 35:e21869. [PMID: 34469026 PMCID: PMC8639177 DOI: 10.1096/fj.202002745r] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/27/2021] [Accepted: 08/09/2021] [Indexed: 11/11/2022]
Abstract
The leucine-rich repeat-containing family 8 member A (LRRC8A) is an essential subunit of the volume-regulated anion channel (VRAC). VRAC is critical for cell volume control, but its broader physiological functions remain under investigation. Recent studies in the field indicate that Lrrc8a disruption in the brain astrocytes reduces neuronal excitability, impairs synaptic plasticity and memory, and protects against cerebral ischemia. In the present work, we generated brain-wide conditional LRRC8A knockout mice (LRRC8A bKO) using NestinCre -driven Lrrc8aflox/flox excision in neurons, astrocytes, and oligodendroglia. LRRC8A bKO animals were born close to the expected Mendelian ratio and developed without overt histological abnormalities, but, surprisingly, all died between 5 and 9 weeks of age with a seizure phenotype, which was confirmed by video and EEG recordings. Brain slice electrophysiology detected changes in the excitability of pyramidal cells and modified GABAergic inputs in the hippocampal CA1 region of LRRC8A bKO. LRRC8A-null hippocampi showed increased immunoreactivity of the astrocytic marker GFAP, indicating reactive astrogliosis. We also found decreased whole-brain protein levels of the GABA transporter GAT-1, the glutamate transporter GLT-1, and the astrocytic enzyme glutamine synthetase. Complementary HPLC assays identified reduction in the tissue levels of the glutamate and GABA precursor glutamine. Together, these findings suggest that VRAC provides vital control of brain excitability in mouse adolescence. VRAC deletion leads to a lethal phenotype involving progressive astrogliosis and dysregulation of astrocytic uptake and supply of amino acid neurotransmitters and their precursors.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Preeti Dohare
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Shaina Orbeta
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Julia W Nalwalk
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Yunfei Huang
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Russell J Ferland
- Department of Biomedical Sciences, University of New England College of Osteopathic Medicine, Biddeford, Maine, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Annalisa Scimemi
- Department of Biology, University at Albany, State University of New York, Albany, New York, USA
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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17
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Hippocampal astrocytic neogenin regulating glutamate uptake, a critical pathway for preventing epileptic response. Proc Natl Acad Sci U S A 2021; 118:2022921118. [PMID: 33850017 DOI: 10.1073/pnas.2022921118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epilepsy, a common neurological disorder, is featured with recurrent seizures. Its underlying pathological mechanisms remain elusive. Here, we provide evidence for loss of neogenin (NEO1), a coreceptor for multiple ligands, including netrins and bone morphological proteins, in the development of epilepsy. NEO1 is reduced in hippocampi from patients with epilepsy based on transcriptome and proteomic analyses. Neo1 knocking out (KO) in mouse brains displays elevated epileptiform spikes and seizure susceptibility. These phenotypes were undetectable in mice, with selectively depleted NEO1 in excitatory (NeuroD6-Cre+) or inhibitory (parvalbumin+) neurons, but present in mice with specific hippocampal astrocytic Neo1 KO. Additionally, neurons in hippocampal dentate gyrus, a vulnerable region in epilepsy, in mice with astrocyte-specific Neo1 KO show reductions in inhibitory synaptic vesicles and the frequency of miniature inhibitory postsynaptic current(mIPSC), but increase of the duration of miniature excitatory postsynaptic current and tonic NMDA receptor currents, suggesting impairments in both GABAergic transmission and extracellular glutamate clearance. Further proteomic and cell biological analyses of cell-surface proteins identified GLAST, a glutamate-aspartate transporter that is marked reduced in Neo1 KO astrocytes and the hippocampus. NEO1 interacts with GLAST and promotes GLAST surface distribution in astrocytes. Expressing NEO1 or GLAST in Neo1 KO astrocytes in the hippocampus abolishes the epileptic phenotype. Taken together, these results uncover an unrecognized pathway of NEO1-GLAST in hippocampal GFAP+ astrocytes, which is critical for GLAST surface distribution and function, and GABAergic transmission, unveiling NEO1 as a valuable therapeutic target to protect the brain from epilepsy.
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18
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Pawlik MJ, Obara-Michlewska M, Popek MP, Czarnecka AM, Czuczwar SJ, Łuszczki J, Kołodziej M, Acewicz A, Wierzba-Bobrowicz T, Albrecht J. Pretreatment with a glutamine synthetase inhibitor MSO delays the onset of initial seizures induced by pilocarpine in juvenile rats. Brain Res 2021; 1753:147253. [PMID: 33422530 DOI: 10.1016/j.brainres.2020.147253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/26/2020] [Accepted: 12/16/2020] [Indexed: 02/06/2023]
Abstract
The contribution of glutamatergic transmission to generation of initial convulsive seizures (CS) is debated. We tested whether pretreatment with a glutamine synthetase (GS) inhibitor, methionine sulfoximine (MSO), affects the onset and progression of initial CS by cholinergic stimulus in juvenile rats. Male rats (24 days old, Sprague Dawley) sequentially received i.p. injections of lithium-carbonate, MSO, methyl-scopolamine, and pilocarpine (Pilo). Pilo was given 150 min after MSO. Animals were continuously monitored using the Racine scale, EEG/EMG and intrahippocampal glutamate (Glu) biosensors. GS activity as measured in hippocampal homogenates, was not altered by MSO at 150 min, showed initial, varied inhibition at 165 (15 min post-Pilo), and dropped down to 11% of control at 60 min post-Pilo, whereas GS protein expression remained unaltered throughout. Pilo did neither modulate the effect of MSO on GS activity nor affect GS activity itself, at any time point. MSO reduced from 32% to 4% the number of animals showing CS during the first 12 min post-Pilo, delayed by ~6 min the appearance of electrographic seizures, and tended to decrease EMG power during ~15 min post-Pilo. The results indicate that MSO impairs an aspect of glutamatergic transmission involved in the transition from the first cholinergic stimulus to the onset of seizures. A continuous rise of extracellular Glu lasting 60 min was insignificantly affected by MSO, leaving the nature of the Glu pool(s) involved in altered glutamatergic transmission undefined.
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Affiliation(s)
- Marek J Pawlik
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland.
| | - Marta Obara-Michlewska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland.
| | - Mariusz P Popek
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland.
| | - Anna Maria Czarnecka
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland.
| | - Stanisław J Czuczwar
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland.
| | - Jarogniew Łuszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland.
| | - Marcin Kołodziej
- Institute of Theory of Electrical Engineering, Measurement and Information Systems, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland.
| | - Albert Acewicz
- Department of Neuropathology, Institute of Psychiatry and Neurology, Jana III Sobieskiego 9, 02-957 Warsaw, Poland.
| | - Teresa Wierzba-Bobrowicz
- Department of Neuropathology, Institute of Psychiatry and Neurology, Jana III Sobieskiego 9, 02-957 Warsaw, Poland.
| | - Jan Albrecht
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland.
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19
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Molina SJ, Buján GE, Guelman LR. Noise-induced hippocampal oxidative imbalance and aminoacidergic neurotransmitters alterations in developing male rats: Influence of enriched environment during adolescence. Dev Neurobiol 2021; 81:164-188. [PMID: 33386696 DOI: 10.1002/dneu.22806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 12/21/2020] [Accepted: 12/26/2020] [Indexed: 12/21/2022]
Abstract
Living in big cities might involuntarily expose people to high levels of noise causing auditory and/or extra-auditory impairments, including adverse effects on central nervous system (CNS) areas such as the hippocampus. In particular, CNS development is a very complex process that can be altered by environmental stimuli. We have previously shown that noise exposure of developing rats can induce hippocampal-related behavioral alterations. However, noise-induced biochemical alterations had not been studied yet. Thus, the aim of this work was to assess whether early noise exposure can affect rat hippocampal oxidative state and aminoacidergic neurotransmission tone. Additionally, the effectiveness of an enriched environment (EE) as a neuroprotective strategy was evaluated. Male Wistar rats were exposed to different noise schemes at 7 or 15 days after birth. Upon weaning, some animals were transferred to an EE whereas others were kept in standard cages. Short- and long-term measurements were performed to evaluate reactive oxygen species, thioredoxins levels and catalase activity as indicators of hippocampal oxidative status as well as glutamic acid decarboxylase and a subtype of glutamate transporter to evaluate aminoacidergic neurotransmission tone. Results showed noise-induced changes in hippocampal oxidative state and aminoacidergic neurotransmission markers that lasted until adolescence and differed according to the scheme and the age of exposure. Finally, EE housing was effective in preventing some of these changes. These findings suggest that CNS development seems to be sensitive to the effects of stressors such as noise, as well as those of an environmental stimulation, favoring prompt and lasting molecular changes.
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Affiliation(s)
- Sonia Jazmín Molina
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Estudios Farmacológicos y Botánicos (CEFyBO, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| | - Gustavo Ezequiel Buján
- Universidad de Buenos Aires, Facultad de Medicina, 1ª Cátedra de Farmacología, Buenos Aires, Argentina
| | - Laura Ruth Guelman
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Estudios Farmacológicos y Botánicos (CEFyBO, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Medicina, 1ª Cátedra de Farmacología, Buenos Aires, Argentina
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20
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Juvale IIA, Che Has AT. Possible interplay between the theories of pharmacoresistant epilepsy. Eur J Neurosci 2020; 53:1998-2026. [PMID: 33306252 DOI: 10.1111/ejn.15079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 11/22/2020] [Accepted: 12/04/2020] [Indexed: 02/06/2023]
Abstract
Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.
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Affiliation(s)
- Iman Imtiyaz Ahmed Juvale
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
| | - Ahmad Tarmizi Che Has
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
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21
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Caudal LC, Gobbo D, Scheller A, Kirchhoff F. The Paradox of Astroglial Ca 2 + Signals at the Interface of Excitation and Inhibition. Front Cell Neurosci 2020; 14:609947. [PMID: 33324169 PMCID: PMC7726216 DOI: 10.3389/fncel.2020.609947] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/03/2020] [Indexed: 12/15/2022] Open
Abstract
Astroglial networks constitute a non-neuronal communication system in the brain and are acknowledged modulators of synaptic plasticity. A sophisticated set of transmitter receptors in combination with distinct secretion mechanisms enables astrocytes to sense and modulate synaptic transmission. This integrative function evolved around intracellular Ca2+ signals, by and large considered as the main indicator of astrocyte activity. Regular brain physiology meticulously relies on the constant reciprocity of excitation and inhibition (E/I). Astrocytes are metabolically, physically, and functionally associated to the E/I convergence. Metabolically, astrocytes provide glutamine, the precursor of both major neurotransmitters governing E/I in the central nervous system (CNS): glutamate and γ-aminobutyric acid (GABA). Perisynaptic astroglial processes are structurally and functionally associated with the respective circuits throughout the CNS. Astonishingly, in astrocytes, glutamatergic as well as GABAergic inputs elicit similar rises in intracellular Ca2+ that in turn can trigger the release of glutamate and GABA as well. Paradoxically, as gliotransmitters, these two molecules can thus strengthen, weaken or even reverse the input signal. Therefore, the net impact on neuronal network function is often convoluted and cannot be simply predicted by the nature of the stimulus itself. In this review, we highlight the ambiguity of astrocytes on discriminating and affecting synaptic activity in physiological and pathological state. Indeed, aberrant astroglial Ca2+ signaling is a key aspect of pathological conditions exhibiting compromised network excitability, such as epilepsy. Here, we gather recent evidence on the complexity of astroglial Ca2+ signals in health and disease, challenging the traditional, neuro-centric concept of segregating E/I, in favor of a non-binary, mutually dependent perspective on glutamatergic and GABAergic transmission.
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Affiliation(s)
- Laura C Caudal
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Davide Gobbo
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Anja Scheller
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
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22
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Long-Term Impact of Early-Life Stress on Hippocampal Plasticity: Spotlight on Astrocytes. Int J Mol Sci 2020; 21:ijms21144999. [PMID: 32679826 PMCID: PMC7404101 DOI: 10.3390/ijms21144999] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 12/15/2022] Open
Abstract
Adverse experiences during childhood are among the most prominent risk factors for developing mood and anxiety disorders later in life. Early-life stress interventions have been established as suitable models to study the neurobiological basis of childhood adversity in rodents. Different models such as maternal separation, impaired maternal care and juvenile stress during the postweaning/prepubertal life phase are utilized. Especially within the limbic system, they induce lasting alterations in neuronal circuits, neurotransmitter systems, neuronal architecture and plasticity that are further associated with emotional and cognitive information processing. Recent studies found that astrocytes, a special group of glial cells, have altered functions following early-life stress as well. As part of the tripartite synapse, astrocytes interact with neurons in multiple ways by affecting neurotransmitter uptake and metabolism, by providing gliotransmitters and by providing energy to neurons within local circuits. Thus, astrocytes comprise powerful modulators of neuronal plasticity and are well suited to mediate the long-term effects of early-life stress on neuronal circuits. In this review, we will summarize current findings on altered astrocyte function and hippocampal plasticity following early-life stress. Highlighting studies for astrocyte-related plasticity modulation as well as open questions, we will elucidate the potential of astrocytes as new targets for interventions against stress-induced neuropsychiatric disorders.
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23
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Qureshi T, Bjørkmo M, Nordengen K, Gundersen V, Utheim TP, Watne LO, Storm-Mathisen J, Hassel B, Chaudhry FA. Slc38a1 Conveys Astroglia-Derived Glutamine into GABAergic Interneurons for Neurotransmitter GABA Synthesis. Cells 2020; 9:E1686. [PMID: 32668809 PMCID: PMC7407890 DOI: 10.3390/cells9071686] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 12/17/2022] Open
Abstract
GABA signaling is involved in a wide range of neuronal functions, such as synchronization of action potential firing, synaptic plasticity and neuronal development. Sustained GABA signaling requires efficient mechanisms for the replenishment of the neurotransmitter pool of GABA. The prevailing theory is that exocytotically released GABA may be transported into perisynaptic astroglia and converted to glutamine, which is then shuttled back to the neurons for resynthesis of GABA-i.e., the glutamate/GABA-glutamine (GGG) cycle. However, an unequivocal demonstration of astroglia-to-nerve terminal transport of glutamine and the contribution of astroglia-derived glutamine to neurotransmitter GABA synthesis is lacking. By genetic inactivation of the amino acid transporter Solute carrier 38 member a1 (Slc38a1)-which is enriched on parvalbumin+ GABAergic neurons-and by intraperitoneal injection of radiolabeled acetate (which is metabolized to glutamine in astroglial cells), we show that Slc38a1 mediates import of astroglia-derived glutamine into GABAergic neurons for synthesis of GABA. In brain slices, we demonstrate the role of Slc38a1 for the uptake of glutamine specifically into GABAergic nerve terminals for the synthesis of GABA depending on demand and glutamine supply. Thus, while leaving room for other pathways, our study demonstrates a key role of Slc38a1 for newly formed GABA, in harmony with the existence of a GGG cycle.
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Affiliation(s)
- Tayyaba Qureshi
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Mona Bjørkmo
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Kaja Nordengen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Vidar Gundersen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Tor Paaske Utheim
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, 0424 Oslo, Norway;
| | - Leiv Otto Watne
- Department of Geriatric Medicine, Oslo University Hospital, 0424 Oslo, Norway;
| | - Jon Storm-Mathisen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
| | - Bjørnar Hassel
- Department of Neurohabilitation, Oslo University Hospital and University of Oslo, 0424 Oslo, Norway;
| | - Farrukh Abbas Chaudhry
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (T.Q.); (M.B.); (K.N.); (V.G.); (J.S.-M.)
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, 0424 Oslo, Norway;
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24
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Bres EE, Safina D, Müller J, Bedner P, Yang H, Helluy X, Shchyglo O, Jansen S, Mark MD, Esser A, Steinhäuser C, Herlitze S, Pietrzik CU, Sirko S, Manahan-Vaughan D, Faissner A. Lipoprotein receptor loss in forebrain radial glia results in neurological deficits and severe seizures. Glia 2020; 68:2517-2549. [PMID: 32579270 DOI: 10.1002/glia.23869] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 05/19/2020] [Accepted: 05/22/2020] [Indexed: 02/06/2023]
Abstract
The Alzheimer disease-associated multifunctional low-density lipoprotein receptor-related protein-1 is expressed in the brain. Recent studies uncovered a role of this receptor for the appropriate functioning of neural stem cells, oligodendrocytes, and neurons. The constitutive knock-out (KO) of the receptor is embryonically lethal. To unravel the receptors' role in the developing brain we generated a mouse mutant by specifically targeting radial glia stem cells of the dorsal telencephalon. The low-density lipoprotein receptor-related protein-1 lineage-restricted KO female and male mice, in contrast to available models, developed a severe neurological phenotype with generalized seizures during early postnatal development. The mechanism leading to a buildup of hyperexcitability and emergence of seizures was traced to a failure in adequate astrocyte development and deteriorated postsynaptic density integrity. The detected impairments in the astrocytic lineage: precocious maturation, reactive gliosis, abolished tissue plasminogen activator uptake, and loss of functionality emphasize the importance of this glial cell type for synaptic signaling in the developing brain. Together, the obtained results highlight the relevance of astrocytic low-density lipoprotein receptor-related protein-1 for glutamatergic signaling in the context of neuron-glia interactions and stage this receptor as a contributing factor for epilepsy.
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Affiliation(s)
- Ewa E Bres
- Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Dina Safina
- Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Julia Müller
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Peter Bedner
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Honghong Yang
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Xavier Helluy
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany.,Department of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr University Bochum, Bochum, Germany
| | - Olena Shchyglo
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Stephan Jansen
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Melanie D Mark
- Behavioral Neuroscience, Ruhr University Bochum, Bochum, Germany
| | | | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, Ruhr University Bochum, Bochum, Germany
| | - Claus U Pietrzik
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Swetlana Sirko
- Department of Physiological Genomics, Biomedical Center (BMC), Ludwig-Maximilians University, Planegg-Martinsried, Germany.,Institute for Stem Cell Research, Helmholtz Zentrum Munich, Neuherberg, Germany
| | | | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum, Bochum, Germany
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25
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Diniz LP, Araujo APB, Matias I, Garcia MN, Barros-Aragão FGQ, de Melo Reis RA, Foguel D, Braga C, Figueiredo CP, Romão L, Gomes FCA. Astrocyte glutamate transporters are increased in an early sporadic model of synucleinopathy. Neurochem Int 2020; 138:104758. [PMID: 32439533 DOI: 10.1016/j.neuint.2020.104758] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 04/29/2020] [Accepted: 05/13/2020] [Indexed: 02/06/2023]
Abstract
α-Synuclein protein (α-syn) is a central player in Parkinson's disease (PD) and in a spectrum of neurodegenerative diseases collectively known as synucleinopathies. These diseases are characterized by abnormal motor symptoms, such as tremor at rest, slowness of movement, rigidity of posture, and bradykinesia. Histopathological features of PD include preferential loss of dopaminergic neurons in the substantia nigra and formation of fibrillar intraneuronal inclusions called Lewy bodies and Lewy neurites, which are composed primarily of the α-syn protein. Currently, it is well accepted that α-syn oligomers (αSO) are the main toxic agent responsible for the etiology of PD. Glutamatergic excitotoxicity is associated with several neurological disorders, including PD. Excess glutamate in the synaptic cleft can be taken up by the astrocytic glutamate transporters GLAST and GLT-1. Although this event is the main defense against glutamatergic excitotoxicity, the molecular mechanisms that regulate this process have not yet been investigated in an early sporadic model of synucleinopathy. Here, using an early sporadic model of synucleinopathy, we demonstrated that the treatment of astrocytes with αSO increased glutamate uptake. This was associated with higher levels of GLAST and GLT-1 in astrocyte cultures and in a mouse model of synucleinopathy 24 h and 45 days after inoculation with αSO, respectively. Pharmacological inhibition of the TGF-β1 (transforming growth factor beta 1) pathway in vivo reverted GLAST/GLT-1 enhancement induced by αSO injection. Therefore, our study describes a new neuroprotective role of astrocytes in an early sporadic model of synucleinopathy and sheds light on the mechanisms of glutamate transporter regulation for neuroprotection against glutamatergic excitotoxicity in synucleinopathy.
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Affiliation(s)
- Luan Pereira Diniz
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Ana Paula Bérgamo Araujo
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Isadora Matias
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Matheus N Garcia
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fernanda G Q Barros-Aragão
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil; Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Débora Foguel
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carolina Braga
- Campus Duque de Caxias, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cláudia P Figueiredo
- Faculdade de Farmácia, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luciana Romão
- Instituto de Ciências Biomédicas, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil.
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Effects of Branched-Chain Amino Acid Supplementation on Spontaneous Seizures and Neuronal Viability in a Model of Mesial Temporal Lobe Epilepsy. J Neurosurg Anesthesiol 2019; 31:247-256. [PMID: 29620688 DOI: 10.1097/ana.0000000000000499] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The essential branched-chain amino acids (BCAAs) leucine, isoleucine, and valine have recently emerged as a potential novel treatment for medically refractory epilepsy. Blood-derived BCAAs can readily enter the brain, where they contribute to glutamate biosynthesis and may either suppress or trigger acute seizures. However, the effects of BCAAs on chronic (ie, spontaneous recurrent) seizures and epilepsy-associated neuron loss are incompletely understood. MATERIALS AND METHODS Sixteen rats with mesial temporal lobe epilepsy were randomized into 2 groups that could drink, ad libitum, either a 4% solution of BCAAs in water (n=8) or pure water (n=8). The frequency and relative percent of convulsive and nonconvulsive spontaneous seizures were monitored for a period of 21 days, and the brains were then harvested for immunohistochemical analysis. RESULTS Although the frequency of convulsive and nonconvulsive spontaneous recurrent seizures over a 3-week drinking/monitoring period were not different between the groups, there were differences in the relative percent of convulsive seizures in the first and third week of treatment. Moreover, the BCAA-treated rats had over 25% fewer neurons in the dentate hilus of the hippocampus compared with water-treated controls. CONCLUSIONS Acute BCAA supplementation reduces seizure propagation, whereas chronic oral supplementation with BCAAs worsens seizure propagation and causes neuron loss in rodents with mesial temporal lobe epilepsy. These findings raise the question of whether such supplementation has a similar effect in humans.
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27
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Xin W, Mironova YA, Shen H, Marino RAM, Waisman A, Lamers WH, Bergles DE, Bonci A. Oligodendrocytes Support Neuronal Glutamatergic Transmission via Expression of Glutamine Synthetase. Cell Rep 2019; 27:2262-2271.e5. [PMID: 31116973 PMCID: PMC6544175 DOI: 10.1016/j.celrep.2019.04.094] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/16/2019] [Accepted: 04/22/2019] [Indexed: 11/30/2022] Open
Abstract
Glutamate has been implicated in a wide range of brain pathologies and is thought to be metabolized via the astrocyte-specific enzyme glutamine synthetase (GS). We show here that oligodendrocytes, the myelinating glia of the central nervous system, also express high levels of GS in caudal regions like the midbrain and the spinal cord. Selective removal of oligodendrocyte GS in mice led to reduced brain glutamate and glutamine levels and impaired glutamatergic synaptic transmission without disrupting myelination. Furthermore, animals lacking oligodendrocyte GS displayed deficits in cocaine-induced locomotor sensitization, a behavior that is dependent on glutamatergic signaling in the midbrain. Thus, oligodendrocytes support glutamatergic transmission through the actions of GS and may represent a therapeutic target for pathological conditions related to brain glutamate dysregulation.
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Affiliation(s)
- Wendy Xin
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Yevgeniya A Mironova
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hui Shen
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA
| | - Rosa A M Marino
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA
| | - Ari Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
| | - Wouter H Lamers
- Academic Medical Center, Tytgat Institute for Liver and Intestinal Research, 1105 BK Amsterdam, the Netherlands
| | - Dwight E Bergles
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Antonello Bonci
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neuroscience, Georgetown University Medical Center, School of Medicine, Washington, DC 20007, USA; Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD 21205, USA.
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28
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Manaserh IH, Chikkamenahalli L, Ravi S, Dube PR, Park JJ, Hill JW. Ablating astrocyte insulin receptors leads to delayed puberty and hypogonadism in mice. PLoS Biol 2019; 17:e3000189. [PMID: 30893295 PMCID: PMC6443191 DOI: 10.1371/journal.pbio.3000189] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 04/01/2019] [Accepted: 03/05/2019] [Indexed: 11/18/2022] Open
Abstract
Insulin resistance and obesity are associated with reduced gonadotropin-releasing hormone (GnRH) release and infertility. Mice that lack insulin receptors (IRs) throughout development in both neuronal and non-neuronal brain cells are known to exhibit subfertility due to hypogonadotropic hypogonadism. However, attempts to recapitulate this phenotype by targeting specific neurons have failed. To determine whether astrocytic insulin sensing plays a role in the regulation of fertility, we generated mice lacking IRs in astrocytes (astrocyte-specific insulin receptor deletion [IRKOGFAP] mice). IRKOGFAP males and females showed a delay in balanopreputial separation or vaginal opening and first estrous, respectively. In adulthood, IRKOGFAP female mice also exhibited longer, irregular estrus cycles, decreased pregnancy rates, and reduced litter sizes. IRKOGFAP mice show normal sexual behavior but hypothalamic-pituitary-gonadotropin (HPG) axis dysregulation, likely explaining their low fecundity. Histological examination of testes and ovaries showed impaired spermatogenesis and ovarian follicle maturation. Finally, reduced prostaglandin E synthase 2 (PGES2) levels were found in astrocytes isolated from these mice, suggesting a mechanism for low GnRH/luteinizing hormone (LH) secretion. These findings demonstrate that insulin sensing by astrocytes is indispensable for the function of the reproductive axis. Additional work is needed to elucidate the role of astrocytes in the maturation of hypothalamic reproductive circuits.
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Affiliation(s)
- Iyad H Manaserh
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
- Center for Diabetes and Endocrine Research, University of Toledo, Toledo, Ohio, United States of America
| | - Lakshmikanth Chikkamenahalli
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Samyuktha Ravi
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Prabhatchandra R Dube
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Joshua J Park
- Center for Diabetes and Endocrine Research, University of Toledo, Toledo, Ohio, United States of America
- Department of Neurosciences, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Jennifer W Hill
- Department of Physiology and Pharmacology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
- Center for Diabetes and Endocrine Research, University of Toledo, Toledo, Ohio, United States of America
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29
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Liang SL. The glutamine-glutamate cycle regulates synaptic glutamate release in the ventrolateral ventromedial nucleus of the hypothalamus of perinatal female rats. J Neuroendocrinol 2018; 30:e12642. [PMID: 30168642 DOI: 10.1111/jne.12642] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/23/2018] [Accepted: 08/27/2018] [Indexed: 12/11/2022]
Abstract
The astrocytic glutamine (Gln)-glutamate (Glu) cycle (GGC) supplies Gln for the regulation of glutamatergic synaptic transmission (GST) in the adult hippocampus. Increased synaptic Glu release in the perinatal ventrolateral ventromedial nucleus of the hypothalamus (vlVMH) modulates sexual differentiation, however, whether GGC regulates GST in the perinatal vlVMH has not been determined. Sex differences in oestradiol (E2 ) levels exist in the neonatal hypothalamus, and E2 increases levels of glutamine synthetase and glutaminase, two key enzymes involved in the GGC. Thus, it is hypothesised that sexually dimorphic phenotypes may exist in glutamatergic synapses associated with the GGC in the vlVMH in perinatal rats. Whole-cell voltage-clamp recordings in vlVMH neurones in brain slices from male and female pups revealed that pharmacological disruption of the GGC by α-(methylamino) isobutyric acid (5 mmol L-1 ), which blocks neuronal Gln uptake; or by l-methionine sulphoximine (1.5 mmol L-1 ), which inhibits astrocytic Gln synthesis, decreased miniature excitatory postsynaptic current (mEPSC) amplitudes in female but not male pups. By contrast, GGC interruptions decreased evoked (e)EPSC amplitudes in both sexes following increased synaptic activity produced by a period of stimulation. In male pups, the decreased eEPSCs were attributable to reduced Glu release, as assessed by paired-pulse stimulations, whereas, in female pups, they were attributable to decreased Glu content in the synaptic vesicles, as measured by strontium-evoked mEPSCs. The l-methionine sulphoximine-mediated decrease in eEPSCs was rapidly rescued by exogenous Gln in female but not male pups. The reductions in mEPSCs and eEPSCs in female pups were accompanied by enhanced blocking effects of the low-affinity Glu AMPA receptor antagonist, γ-d-glutamylglycine, consistent with diminished Glu release. In conclusion, female, but not male pups, rely on constitutive astrocytic Gln for sustained synaptic Glu release in the vlVMH. This glutamatergic synaptic phenotype may be associated with brain and behaviour feminisation and/or defeminisation in rats.
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Affiliation(s)
- Shu-Ling Liang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, Taiwan
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30
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The C9ORF72 Gene, Implicated in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia, Encodes a Protein That Functions in Control of Endothelin and Glutamate Signaling. Mol Cell Biol 2018; 38:MCB.00155-18. [PMID: 30150298 DOI: 10.1128/mcb.00155-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 08/15/2018] [Indexed: 02/08/2023] Open
Abstract
A GGGGCC repeat expansion in the C9ORF72 (C9) gene is the most common known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Several mechanisms have been proposed to account for its toxicity, including the possibility that reduced C9 protein levels contribute to disease. To investigate this possibility, we examined the effects of reduced C9 levels in several cell systems. We first showed that C9 knockdown (KD) in U87 glioblastoma cells results in striking morphological changes, including vacuolization and alterations in cell size. Unexpectedly, RNA analysis revealed changes in expression of many genes, including genes involved in endothelin (EDN) signaling and immune system pathways and multiple glutamate cycling genes (e.g., EAAT2), which were verified in several cell models, including astrocytes and brain samples from C9-positive patients. Consistent with deregulation of the glutamate cycling genes, elevated intracellular glutamate was detected in both KD cells and patient astrocytes. Importantly, levels of mRNAs encoding EDN1 and its receptors, known to be elevated in ALS, were sharply increased by C9 KD, likely resulting from an observed activation of NF-κB signaling and/or a possible role of a C9 isoform in gene control.
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31
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Son H, Baek JH, Go BS, Jung DH, Sontakke SB, Chung HJ, Lee DH, Roh GS, Kang SS, Cho GJ, Choi WS, Lee DK, Kim HJ. Glutamine has antidepressive effects through increments of glutamate and glutamine levels and glutamatergic activity in the medial prefrontal cortex. Neuropharmacology 2018; 143:143-152. [PMID: 30266598 DOI: 10.1016/j.neuropharm.2018.09.040] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/21/2018] [Accepted: 09/24/2018] [Indexed: 01/05/2023]
Abstract
Emerging evidence has shown the low levels of glutamate (Glu) and glutamine (Gln) and the hypoactivity in the cortex of patients with depression. The hypoactivity is closely related with low frequency of glutamatergic signaling that is affected by the levels of Glu and Gln. Thus, we hypothesized that there might be a causality among low levels of Glu and Gln, hypoactive glutamatergic neurotransmissions, and depressive behaviors. Here, we found low Glu and Gln levels and low frequency of spontaneous excitatory postsynaptic current (sEPSC) of glutamatergic neurons in the medial prefrontal cortex (mPFC) of chronic immobilization stress (CIS)-induced depressed mice. The depressed mice also showed hypoactive Gln synthetase (GS). Inhibition of GS by methionine sulfoximine (MSO) decreased Glu and Gln levels and increased depressive behaviors with low frequency of sEPSC in the mPFC, indicating that Glu and Gln decrements cause hypoactive glutamatergic neurotransmissions and depressive behaviors. Both Glu and Gln could increase sEPSC of glutamatergic neurons in the mPFC on slice patch, but only Gln overcame MSO to increase sEPSC, suggesting that exogenous Gln would recover CIS-induced low frequency of sEPSC caused by hypoactive GS and act as an antidepressant. Expectedly, Gln supplementation showed antidepressant effects against CIS; it increased glutamatergic neurotransmissions with Glu and Gln increment in the mPFC and attenuated depressive behaviors. Moreover, selective glutamatergic activation in the mPFC by optogenetics decreased depressive behavior. In conclusion, depressive behaviors evoked by chronic stress were due to hypoactive glutamatergic neurons in the mPFC caused by low levels of Glu and Gln, and exogenous Gln can be used as an alternative antidepressant to increase glutamatergic neurotransmission.
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Affiliation(s)
- Hyeonwi Son
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Ji Hyeong Baek
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Bok Soon Go
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Doo-Hyuk Jung
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Sneha B Sontakke
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju-daero, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Hye Jin Chung
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju-daero, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Dong Hoon Lee
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Gu Seob Roh
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Sang Soo Kang
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Gyeong Jae Cho
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Wan Sung Choi
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Dong Kun Lee
- Department of Physiology, Institute of Health Sciences, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea.
| | - Hyun Joon Kim
- Department of Anatomy and Convergence Medical Sciences, Institute of Health Sciences, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, 15 Jinju-daero 816 Beongil, Jinju, Gyeongnam, 52727, Republic of Korea.
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Dong W, Todd AC, Bröer A, Hulme SR, Bröer S, Billups B. PKC-Mediated Modulation of Astrocyte SNAT3 Glutamine Transporter Function at Synapses in Situ. Int J Mol Sci 2018; 19:ijms19040924. [PMID: 29561757 PMCID: PMC5979592 DOI: 10.3390/ijms19040924] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/07/2018] [Accepted: 03/15/2018] [Indexed: 01/13/2023] Open
Abstract
Astrocytes are glial cells that have an intimate physical and functional association with synapses in the brain. One of their main roles is to recycle the neurotransmitters glutamate and gamma-aminobutyric acid (GABA), as a component of the glutamate/GABA-glutamine cycle. They perform this function by sequestering neurotransmitters and releasing glutamine via the neutral amino acid transporter SNAT3. In this way, astrocytes regulate the availability of neurotransmitters and subsequently influence synaptic function. Since many plasma membrane transporters are regulated by protein kinase C (PKC), the aim of this study was to understand how PKC influences SNAT3 glutamine transport in astrocytes located immediately adjacent to synapses. We studied SNAT3 transport by whole-cell patch-clamping and fluorescence pH imaging of single astrocytes in acutely isolated brainstem slices, adjacent to the calyx of the Held synapse. Activation of SNAT3-mediated glutamine transport in these astrocytes was reduced to 77 ± 6% when PKC was activated with phorbol 12-myristate 13-acetate (PMA). This effect was very rapid (within ~20 min) and eliminated by application of bisindolylmaleimide I (Bis I) or 7-hydroxystaurosporine (UCN-01), suggesting that activation of conventional isoforms of PKC reduces SNAT3 function. In addition, cell surface biotinylation experiments in these brain slices show that the amount of SNAT3 in the plasma membrane is reduced by a comparable amount (to 68 ± 5%) upon activation of PKC. This indicates a role for PKC in dynamically controlling the trafficking of SNAT3 transporters in astrocytes in situ. These data demonstrate that PKC rapidly regulates the astrocytic glutamine release mechanism, which would influence the glutamine availability for adjacent synapses and control levels of neurotransmission.
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Affiliation(s)
- Wuxing Dong
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
| | - Alison C Todd
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
- Centre for Discovery Brain Sciences, School of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK.
| | - Angelika Bröer
- Research School of Biology, The Australian National University, Linnaeus Way 134, Canberra ACT 2601, Australia.
| | - Sarah R Hulme
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
| | - Stefan Bröer
- Research School of Biology, The Australian National University, Linnaeus Way 134, Canberra ACT 2601, Australia.
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
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Jha SK, Jha NK, Kumar D, Sharma R, Shrivastava A, Ambasta RK, Kumar P. Stress-Induced Synaptic Dysfunction and Neurotransmitter Release in Alzheimer's Disease: Can Neurotransmitters and Neuromodulators be Potential Therapeutic Targets? J Alzheimers Dis 2018; 57:1017-1039. [PMID: 27662312 DOI: 10.3233/jad-160623] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The communication between neurons at synaptic junctions is an intriguing process that monitors the transmission of various electro-chemical signals in the central nervous system. Albeit any aberration in the mechanisms associated with transmission of these signals leads to loss of synaptic contacts in both the neocortex and hippocampus thereby causing insidious cognitive decline and memory dysfunction. Compelling evidence suggests that soluble amyloid-β (Aβ) and hyperphosphorylated tau serve as toxins in the dysfunction of synaptic plasticity and aberrant neurotransmitter (NT) release at synapses consequently causing a cognitive decline in Alzheimer's disease (AD). Further, an imbalance between excitatory and inhibitory neurotransmission systems induced by impaired redox signaling and altered mitochondrial integrity is also amenable for such abnormalities. Defective NT release at the synaptic junction causes several detrimental effects associated with altered activity of synaptic proteins, transcription factors, Ca2+ homeostasis, and other molecules critical for neuronal plasticity. These detrimental effects further disrupt the normal homeostasis of neuronal cells and thereby causing synaptic loss. Moreover, the precise mechanistic role played by impaired NTs and neuromodulators (NMs) and altered redox signaling in synaptic dysfunction remains mysterious, and their possible interlink still needs to be investigated. Therefore, this review elucidates the intricate role played by both defective NTs/NMs and altered redox signaling in synaptopathy. Further, the involvement of numerous pharmacological approaches to compensate neurotransmission imbalance has also been discussed, which may be considered as a potential therapeutic approach in synaptopathy associated with AD.
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Kielbinski M, Gzielo K, Soltys Z. Review: Roles for astrocytes in epilepsy: insights from malformations of cortical development. Neuropathol Appl Neurobiol 2018; 42:593-606. [PMID: 27257021 DOI: 10.1111/nan.12331] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 05/25/2016] [Accepted: 06/03/2016] [Indexed: 12/25/2022]
Abstract
Malformations of cortical development (MCDs), such as cortical dysplasia and tuberous sclerosis complex, are common causes of intractable epilepsy, especially in paediatric patients. Recently, mounting evidence points to a common pathology of these disorders. Hyperactivation of mammalian target of rapamycin (mTOR) has been proposed as a central mechanism in most, if not all, MCDs. The transition from mTOR hyperactivation and cellular abnormalities to large-scale functional changes and seizure is, however, not fully understood. In this article we set out to review currently available information regarding MCD pathology, focusing on glial cells - especially astrocytes - and their interactions with the brain vascular system. A large body of evidence points to these elements as potential targets in MCD. Here, we attempt to provide a review of this evidence and propose some hypotheses regarding the possible chain of events linking primary glial dysfunction and epilepsy. We focus on extracellular matrix remodelling, blood-brain barrier leakage and failure of astrocyte-dependent removal of extracellular debris. We posit that the failure of these systems results in a chronically pro-inflammatory environment, maintaining local astrocytes in a state of gliosis, with increased susceptibility to seizures as a consequence.
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Affiliation(s)
- M Kielbinski
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - K Gzielo
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Z Soltys
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
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Mei YY, Wu DC, Zhou N. Astrocytic Regulation of Glutamate Transmission in Schizophrenia. Front Psychiatry 2018; 9:544. [PMID: 30459650 PMCID: PMC6232167 DOI: 10.3389/fpsyt.2018.00544] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/12/2018] [Indexed: 01/19/2023] Open
Abstract
According to the glutamate hypothesis of schizophrenia, the abnormality of glutamate transmission induced by hypofunction of NMDA receptors (NMDARs) is causally associated with the positive and negative symptoms of schizophrenia. However, the underlying mechanisms responsible for the changes in glutamate transmission in schizophrenia are not fully understood. Astrocytes, the major regulatory glia in the brain, modulate not only glutamate metabolism but also glutamate transmission. Here we review the recent progress in understanding the role of astrocytes in schizophrenia. We focus on the astrocytic mechanisms of (i) glutamate synthesis via the glutamate-glutamine cycle, (ii) glutamate clearance by excitatory amino acid transporters (EAATs), (iii) D-serine release to activate NMDARs, and (iv) glutamatergic target engagement biomarkers. Abnormality in these processes is highly correlated with schizophrenia phenotypes. These findings will shed light upon further investigation of pathogenesis as well as improvement of biomarkers and therapies for schizophrenia.
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Affiliation(s)
- Yu-Ying Mei
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
| | - Dong Chuan Wu
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
| | - Ning Zhou
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
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36
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Heterogeneity and function of hippocampal macroglia. Cell Tissue Res 2017; 373:653-670. [PMID: 29204745 DOI: 10.1007/s00441-017-2746-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022]
Abstract
The contribution of glial cells to normal and impaired hippocampal function is increasingly being recognized, although important questions as to the mechanisms that these cells use for their crosstalk with neurons and capillaries are still unanswered or lead to controversy. Astrocytes in the hippocampus are morphologically variable and a single cell contacts with its processes more than 100,000 synapses. They predominantly express inward rectifier K+ channels and transporters serving homeostatic function but may also release gliotransmitters to modify neuronal signaling and brain circulation. Intracellular Ca2+ transients are key events in the interaction of astrocytes with neurons and the vasculature. Hippocampal NG2 glia represent a population of cells with proliferative capacity throughout adulthood. Intriguingly, they receive direct synaptic input from pyramidal neurons and interneurons and express a multitude of ion channels and receptors. Despite in-depth knowledge about the features of these transmembrane proteins, the physiological impact of NG2 glial cells and their synaptic input remain nebulous. Because of the low abundance of oligodendrocytes in the hippocampus, limited information is available about their specific properties. Given the multitude of signaling molecules expressed by the various types of hippocampal glial cells (and because of space constraints), we focus, in this review, on those properties that are considered key for the interaction of the respective cell type with its neighborhood.
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Taccola G, Sayenko D, Gad P, Gerasimenko Y, Edgerton VR. And yet it moves: Recovery of volitional control after spinal cord injury. Prog Neurobiol 2017; 160:64-81. [PMID: 29102670 PMCID: PMC5773077 DOI: 10.1016/j.pneurobio.2017.10.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 10/09/2017] [Accepted: 10/21/2017] [Indexed: 12/12/2022]
Abstract
Preclinical and clinical neurophysiological and neurorehabilitation research has generated rather surprising levels of recovery of volitional sensory-motor function in persons with chronic motor paralysis following a spinal cord injury. The key factor in this recovery is largely activity-dependent plasticity of spinal and supraspinal networks. This key factor can be triggered by neuromodulation of these networks with electrical and pharmacological interventions. This review addresses some of the systems-level physiological mechanisms that might explain the effects of electrical modulation and how repetitive training facilitates the recovery of volitional motor control. In particular, we substantiate the hypotheses that: (1) in the majority of spinal lesions, a critical number and type of neurons in the region of the injury survive, but cannot conduct action potentials, and thus are electrically non-responsive; (2) these neuronal networks within the lesioned area can be neuromodulated to a transformed state of electrical competency; (3) these two factors enable the potential for extensive activity-dependent reorganization of neuronal networks in the spinal cord and brain, and (4) propriospinal networks play a critical role in driving this activity-dependent reorganization after injury. Real-time proprioceptive input to spinal networks provides the template for reorganization of spinal networks that play a leading role in the level of coordination of motor pools required to perform a given functional task. Repetitive exposure of multi-segmental sensory-motor networks to the dynamics of task-specific sensory input as occurs with repetitive training can functionally reshape spinal and supraspinal connectivity thus re-enabling one to perform complex motor tasks, even years post injury.
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Affiliation(s)
- G Taccola
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - D Sayenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - P Gad
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Y Gerasimenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Pavlov Institute of Physiology, St. Petersburg 199034, Russia
| | - V R Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Department of Neurobiology, University of California, Los Angeles, CA 90095 USA; Department of Neurosurgery, University of California, Los Angeles, CA 90095 USA; Brain Research Institute, University of California, Los Angeles, CA 90095 USA; The Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, 2007 NSW, Australia; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain.
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38
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Boison D, Steinhäuser C. Epilepsy and astrocyte energy metabolism. Glia 2017; 66:1235-1243. [PMID: 29044647 DOI: 10.1002/glia.23247] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 08/29/2017] [Accepted: 10/02/2017] [Indexed: 12/17/2022]
Abstract
Epilepsy is a complex neurological syndrome characterized by neuronal hyperexcitability and sudden, synchronized electrical discharges that can manifest as seizures. It is now increasingly recognized that impaired astrocyte function and energy homeostasis play key roles in the pathogenesis of epilepsy. Excessive neuronal discharges can only happen, if adequate energy sources are made available to neurons. Conversely, energy depletion during seizures is an endogenous mechanism of seizure termination. Astrocytes control neuronal energy homeostasis through neurometabolic coupling. In this review, we will discuss how astrocyte dysfunction in epilepsy leads to distortion of key metabolic and biochemical mechanisms. Dysfunctional glutamate metabolism in astrocytes can directly contribute to neuronal hyperexcitability. Closure of astrocyte intercellular gap junction coupling as observed early during epileptogenesis limits activity-dependent trafficking of energy metabolites, but also impairs clearance of the extracellular space from accumulation of K+ and glutamate. Dysfunctional astrocytes also increase the metabolism of adenosine, a metabolic product of ATP degradation that broadly inhibits energy-consuming processes as an evolutionary adaptation to conserve energy. Due to the critical role of astroglial energy homeostasis in the control of neuronal excitability, metabolic therapeutic approaches that prevent the utilization of glucose might represent a potent antiepileptic strategy. In particular, high fat low carbohydrate "ketogenic diets" as well as inhibitors of glycolysis and lactate metabolism are of growing interest for the therapy of epilepsy.
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Affiliation(s)
- Detlev Boison
- R.S. Dow Neurobiology Laboratories, Legacy Research Institute, Portland, Oregon
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Todd AC, Marx MC, Hulme SR, Bröer S, Billups B. SNAT3-mediated glutamine transport in perisynaptic astrocytesin situis regulated by intracellular sodium. Glia 2017; 65:900-916. [DOI: 10.1002/glia.23133] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/12/2017] [Accepted: 02/08/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Alison C. Todd
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
- Centre for Integrative Physiology, School of Biomedical Sciences; University of Edinburgh; Edinburgh EH8 9XD United Kingdom
| | - Mari-Carmen Marx
- Department of Pharmacology; University of Cambridge; Tennis Court Road Cambridge CB2 1BT United Kingdom
| | - Sarah R. Hulme
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
| | - Stefan Bröer
- Research School of Biology; The Australian National University; Linnaeus Way 134 Canberra ACT 2601 Australia
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
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40
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Sun HL, Zhu W, Zhang YR, Pan XH, Zhang JR, Chen XM, Liu YX, Li SC, Wang QY, Deng DP. Altered glutamate metabolism contributes to antiepileptogenic effects in the progression from focal seizure to generalized seizure by low-frequency stimulation in the ventral hippocampus. Epilepsy Behav 2017; 68:1-7. [PMID: 28109982 DOI: 10.1016/j.yebeh.2016.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/04/2016] [Accepted: 09/04/2016] [Indexed: 12/16/2022]
Abstract
As a promising method for treating intractable epilepsy, the inhibitory effect of low-frequency stimulation (LFS) is well known, although its mechanisms remain unclear. Excessive levels of cerebral glutamate are considered a crucial factor for epilepsy. Therefore, we designed experiments to investigate the crucial parts of the glutamate cycle. We evaluated glutamine synthetase (GS, metabolizes glutamate), glutaminase (synthesizes glutamate), and glutamic acid decarboxylase (GAD, a γ-aminobutyric acid [GABA] synthetase) in different regions of the brain, including the dentate gyrus (DG), CA3, and CA1 subregions of the hippocampus, and the cortex, using western blots, immunohistochemistry, and enzyme activity assays. Additionally, the concentrations of glutamate, GABA, and glutamine (a product of GS) were measured using high-performance liquid chromatography (HPLC) in the same subregions. The results indicated that a transiently promoted glutamate cycle was closely involved in the progression from focal to generalized seizure. Low-frequency stimulation (LFS) delivered to the ventral hippocampus had an antiepileptogenic effect in rats exposed to amygdaloid-kindling stimulation. Simultaneously, LFS could partly reverse the effects of the promoted glutamate cycle, including increased GS function, accelerated glutamate-glutamine cycling, and an unbalanced glutamate/GABA ratio, all of which were induced by amygdaloid kindling in the DG when seizures progressed to stage 4. Moreover, glutamine treatment reversed the antiepileptic effect of LFS with regard to both epileptic severity and susceptibility. Our results suggest that the effects of LFS on the glutamate cycle may contribute to the antiepileptogenic role of LFS in the progression from focal to generalized seizure.
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Affiliation(s)
- Hong-Liu Sun
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Wei Zhu
- Institute of Radiation Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Yu-Rong Zhang
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Xiao-Hong Pan
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Jun-Ru Zhang
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Xiang-Ming Chen
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Yu-Xia Liu
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Shu-Cui Li
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China
| | - Qiao-Yun Wang
- School of Pharmaceutical Sciences, Binzhou Medical University, Yantai 264003, China.
| | - Da-Ping Deng
- Institute of Radiation Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China.
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41
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Kwon YO, Hong JT, Oh KW. Rosmarinic Acid Potentiates Pentobarbital-Induced Sleep Behaviors and Non-Rapid Eye Movement (NREM) Sleep through the Activation of GABA A-ergic Systems. Biomol Ther (Seoul) 2017; 25:105-111. [PMID: 27469144 PMCID: PMC5340534 DOI: 10.4062/biomolther.2016.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/16/2016] [Accepted: 05/11/2016] [Indexed: 12/31/2022] Open
Abstract
It has been known that RA, one of major constituents of Perilla frutescens which has been used as a traditional folk remedy for sedation in oriental countries, shows the anxiolytic-like and sedative effects. This study was performed to know whether RA may enhance pentobarbital-induced sleep through γ-aminobutyric acid (GABA)A-ergic systems in rodents. RA (0.5, 1.0 and 2.0 mg/ kg, p.o.) reduced the locomotor activity in mice. RA decreased sleep latency and increased the total sleep time in pentobarbital (42 mg/kg, i.p.)-induced sleeping mice. RA also increased sleeping time and number of falling sleep mice after treatment with sub-hypnotic pentobarbital (28 mg/kg, i.p.). In electroencephalogram (EEG) recording, RA (2.0 mg/kg) not only decreased the counts of sleep/wake cycles and REM sleep, but also increased the total and NREM sleep in rats. The power density of NREM sleep showed the increase in δ-waves and the decrease in α-waves. On the other hand, RA (0.1, 1.0 and 10 μg/ml) increased intracellular Cl- influx in the primary cultured hypothalamic cells of rats. RA (p.o.) increased the protein expression of glutamic acid decarboxylase (GAD65/67) and GABAA receptors subunits except β1 subunit. In conclusion, RA augmented pentobarbital-induced sleeping behaviors through GABAA-ergic transmission. Thus, it is suggested that RA may be useful for the treatment of insomnia.
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Affiliation(s)
- Yeong Ok Kwon
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Jin Tae Hong
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Ki-Wan Oh
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Republic of Korea
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42
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Massively augmented hippocampal dentate granule cell activation accompanies epilepsy development. Sci Rep 2017; 7:42090. [PMID: 28218241 PMCID: PMC5316990 DOI: 10.1038/srep42090] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/04/2017] [Indexed: 11/12/2022] Open
Abstract
In a mouse model of temporal lobe epilepsy, multicellular calcium imaging revealed that disease emergence was accompanied by massive amplification in the normally sparse, afferent stimulation-induced activation of hippocampal dentate granule cells. Patch recordings demonstrated reductions in local inhibitory function within the dentate gyrus at time points where sparse activation was compromised. Mimicking changes in inhibitory synaptic function and transmembrane chloride regulation was sufficient to elicit the dentate gyrus circuit collapse evident during epilepsy development. Pharmacological blockade of outward chloride transport had no effect during epilepsy development, and significantly increased granule cell activation in both control and chronically epileptic animals. This apparent occlusion effect implicates reduction in chloride extrusion as a mechanism contributing to granule cell hyperactivation specifically during early epilepsy development. Glutamine plays a significant role in local synthesis of GABA in synapses. In epileptic mice, sparse granule cell activation could be restored by glutamine application, implicating compromised GABA synthesis. Glutamine had no effect on granule cell activation earlier, during epilepsy development. We conclude that compromised feedforward inhibition within the local circuit generates the massive dentate gyrus circuit hyperactivation evident in animals during and following epilepsy development. However, the mechanisms underlying this disinhibition diverge significantly as epilepsy progresses.
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43
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Huang Y, Shen Z, Hu L, Xia F, Li Y, Zhuang J, Chen P, Huang Q. Exposure of mother rats to chronic unpredictable stress before pregnancy alters the metabolism of gamma-aminobutyric acid and glutamate in the right hippocampus of offspring in early adolescence in a sexually dimorphic manner. Psychiatry Res 2016; 246:236-245. [PMID: 27723521 DOI: 10.1016/j.psychres.2016.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 10/01/2016] [Accepted: 10/02/2016] [Indexed: 01/18/2023]
Abstract
There is increasing evidence that mothers' exposure to stress before or during pregnancy is linked to an incidence of psychiatric disorders in offspring. However, a few studies have estimated the role of sex in the detrimental effects of pre-gestational stress on the offspring rats at early adolescence. Sex differences regarding the metabolism of gamma-aminobutyric acid and glutamate in the right hippocampus were investigated by MRS when the offspring rats reached 30 days. Additionally, the impact of pre-gestational stress exposed on an additional short-term acute stressor, such as forced swim, was examined in the male and female offspring rats. Our findings showed female offspring rats were more vulnerable to stressful conditions for either pre-gestational stress or acute stress in early adolescence, and had decreased GABA/Cr+PCr and Glu/Cr+PCr in the right hippocampus. Interestingly, in response to forced swim, male offspring rats whose mothers were exposed to pre-gestational stress were more affected by the short-term acute stressor and this was manifested by change of Glu/GABA and Glu/Gln in the right hippocampus. These data indicated that although female offspring rats were more vulnerable to pre-gestational stress from their mothers than males, in response to an additional acute stressor they showed better response. Therefore, both sexually dimorphic manner and combination of stressful procedures should be carefully considered in the study of stress-related psychiatric disorders in early adolescence.
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Affiliation(s)
- Yuejun Huang
- Department of Pediatrics, First Affiliated Hospital of Jinan University, West Huangpu Rd, Guangzhou 510632, Guangdong, China; Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
| | - Zhiwei Shen
- Department of Imageology, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
| | - Liu Hu
- Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
| | - Fang Xia
- Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
| | - Yuewa Li
- Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
| | - Jingwen Zhuang
- Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China.
| | - Peishan Chen
- Department of Obstetrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China.
| | - Qingjun Huang
- Joint Lab of Biological Psychiatry, Mental Health Center of Shantou University, Taishan Rd, Shantou 515041, Guangdong, China.
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44
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Chrobok L, Palus K, Jeczmien-Lazur JS, Chrzanowska A, Kepczynski M, Lewandowski MH. Disinhibition of the intergeniculate leaflet network in the WAG/Rij rat model of absence epilepsy. Exp Neurol 2016; 289:103-116. [PMID: 28041911 DOI: 10.1016/j.expneurol.2016.12.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 12/21/2016] [Accepted: 12/25/2016] [Indexed: 01/18/2023]
Abstract
The intergeniculate leaflet (IGL) of the thalamus is a retinorecipient structure implicated in orchestrating circadian rhythmicity. The IGL network is highly GABAergic and consists mainly of neuropeptide Y-synthesising and enkephalinergic neurons. A high density of GFAP-immunoreactive astrocytes has been observed in the IGL, with a probable function in guarding neuronal inhibition. Interestingly, putatively enkephalinergic IGL neurons generate action potentials with an infra-slow oscillatory (ISO) pattern in vivo in urethane anesthetised Wistar rats, under light-on conditions only. Absence epilepsy (AE) is a disease characterised by spike-wave discharges present in the encephalogram, directly caused by hypersynchronous thalamo-cortical oscillations. Many pathologies connected with the arousal system, such as abnormalities in sleep architecture and an insufficient brain sleep-promoting system accompany the epileptic phenotype. We hypothesise that disturbances in the function of biological clock structures, controlling this rhythmic physiological process, may be responsible for the observed pathomechanism. To test this hypothesis, we performed an in vitro patch-clamp study on WAG/Rij rats, a well-validated genetic model of AE, in order to assess dampened GABAergic synaptic transmission in the IGL expressed as a lower IPSC amplitude and reduced sIPSC frequency. Moreover, our in vivo extracellular recordings showed higher firing rate of ISO IGL neurons with an abnormal reaction to a change in constant illumination (maintenance of rhythmic neuronal activity in darkness) in the AE model. Additional immunohistochemical experiments indicated astrogliosis in the area of the IGL, which may partially underlie the observed changes in inhibition. Altogether, the data presented here show for the first time the disinhibition of IGL neurons in a model of AE, thereby proposing the possible involvement of circadian-related brain structures in the epileptic phenotype.
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Affiliation(s)
- Lukasz Chrobok
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University in Krakow, Krakow, Poland.
| | - Katarzyna Palus
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University in Krakow, Krakow, Poland.
| | | | - Anna Chrzanowska
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University in Krakow, Krakow, Poland.
| | - Mariusz Kepczynski
- Faculty of Chemistry, Jagiellonian University in Krakow, Krakow, Poland.
| | - Marian Henryk Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University in Krakow, Krakow, Poland.
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Woo JH, Ha TW, Kang JS, Hong JT, Oh KW. Potentiation of decursinol angelate on pentobarbital-induced sleeping behaviors via the activation of GABA A-ergic systems in rodents. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 21:27-36. [PMID: 28066138 PMCID: PMC5214908 DOI: 10.4196/kjpp.2017.21.1.27] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/29/2016] [Accepted: 08/18/2016] [Indexed: 11/15/2022]
Abstract
Angelicae Gigantis Radix (AGR, Angelica gigas) has been used for a long time as a traditional folk medicine in Korea and oriental countries. Decursinol angelate (DCA) is structurally isomeric decursin, one of the major components of AGR. This study was performed to confirm whether DCA augments pentobarbital-induced sleeping behaviors via the activation of GABAA-ergic systems in animals. Oral administration of DCA (10, 25 and 50 mg/kg) markedly suppressed spontaneous locomotor activity. DCA also prolonged sleeping time, and decreased the sleep latency by pentobarbital (42 mg/kg), in a dose-dependent manner, similar to muscimol, both at the hypnotic (42 mg/kg) and sub-hypnotic (28 mg/kg) dosages. Especially, DCA increased the number of sleeping animals in the sub-hypnotic dosage. DCA (50 mg/kg, p.o.) itself modulated sleep architectures; DCA reduced the counts of sleep/wake cycles. At the same time, DCA increased total sleep time, but not non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. In the molecular experiments. DCA (0.001, 0.01 and 0.1 µg/ml) increased intracellular Cl- influx level in hypothalamic primary cultured neuronal cells of rats. In addition, DCA increased the protein expression of glutamic acid decarboxylase (GAD65/67) and GABAA receptors subtypes. Taken together, these results suggest that DCA potentiates pentobarbital-induced sleeping behaviors through the activation of GABAA-ergic systems, and can be useful in the treatment of insomnia.
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Affiliation(s)
- Jae Hoon Woo
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Korea
| | - Tae-Woo Ha
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Korea
| | - Jae-Seon Kang
- College of Pharmacy, Kyungsung University, Busan, 48434, Korea
| | - Jin Tae Hong
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Korea
| | - Ki-Wan Oh
- College of Pharmacy and Medical Research Center, Chungbuk National University, Cheongju 28644, Korea
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46
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Garnier A, Vidal A, Benali H. A Theoretical Study on the Role of Astrocytic Activity in Neuronal Hyperexcitability by a Novel Neuron-Glia Mass Model. JOURNAL OF MATHEMATICAL NEUROSCIENCE 2016; 6:10. [PMID: 28004309 PMCID: PMC5177605 DOI: 10.1186/s13408-016-0042-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 11/26/2016] [Indexed: 05/07/2023]
Abstract
Recent experimental evidence on the clustering of glutamate and GABA transporters on astrocytic processes surrounding synaptic terminals pose the question of the functional relevance of the astrocytes in the regulation of neural activity. In this perspective, we introduce a new computational model that embeds recent findings on neuron-astrocyte coupling at the mesoscopic scale intra- and inter-layer local neural circuits. The model consists of a mass model for the neural compartment and an astrocyte compartment which controls dynamics of extracellular glutamate and GABA concentrations. By arguments based on bifurcation theory, we use the model to study the impact of deficiency of astrocytic glutamate and GABA uptakes on neural activity. While deficient astrocytic GABA uptake naturally results in increased neuronal inhibition, which in turn results in a decreased neuronal firing, deficient glutamate uptake by astrocytes may either decrease or increase neuronal firing either transiently or permanently. Given the relevance of neuronal hyperexcitability (or lack thereof) in the brain pathophysiology, we provide biophysical conditions for the onset identifying different physiologically relevant regimes of operation for astrocytic uptake transporters.
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Affiliation(s)
- Aurélie Garnier
- Laboratoire d’Imagerie Biomédicale (LIB), Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Paris, 75013 France
| | - Alexandre Vidal
- Laboratoire de Mathématiques et Modélisation d’Évry (LaMME), CNRS UMR 8071, Université d’Évry-Val-d’Essonne, Évry, 91000 France
| | - Habib Benali
- Laboratoire d’Imagerie Biomédicale (LIB), Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Paris, 75013 France
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Trabelsi Y, Amri M, Becq H, Molinari F, Aniksztejn L. The conversion of glutamate by glutamine synthase in neocortical astrocytes from juvenile rat is important to limit glutamate spillover and peri/extrasynaptic activation of NMDA receptors. Glia 2016; 65:401-415. [PMID: 27862359 DOI: 10.1002/glia.23099] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 12/31/2022]
Abstract
Glutamate transporters (EAATs) are important to maintain spatial and temporal specificity of synaptic transmission. Their efficiency to uptake and transport glutamate into the intracellular space depends on several parameters including the intracellular concentrations of Na+ and glutamate, the elevations of which may slow down the cycling rate of EAATs. In astrocytes, glutamate is maintained at low concentration due to the presence of specific enzymes such as glutamine synthase (GS). GS inhibition results in cytosolic accumulation of glutamate suggesting that the conversion of glutamate by GS is important for EAATs operation. Here we recorded astrocytes from juvenile rat neocortical slices and analyzed the consequences of elevated intracellular glutamate concentrations and of GS inhibition on the time course of synaptically evoked transporter current (STC). In slices from rats treated with methionine sulfoximine (MSO), a GS inhibitor, STC evoked by short burst of high frequency stimulation (HFS; 100 Hz for 100 ms) but not by low frequency stimulation (LFS; 0.1 Hz) was twice slower than STC evoked from saline injected rats. Same results were obtained for astrocytes recorded with pipette containing 3-10 mM glutamate and compared with cells recorded with 0 or1 mM glutamate in the patch pipette. We also showed that HFS elicited significantly larger NMDAR-excitatory postsynaptic currents (EPSCs) with a stronger peri/extrasynaptic component in pyramidal cells from MSO-treated compared with saline treated rats. Taken together our data demonstrate that the conversion of glutamate by GS is fundamental to ensure an efficient clearance of glutamate by EAATs and to prevent glutamate spillover. GLIA 2017;65:401-415.
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Affiliation(s)
- Yosra Trabelsi
- Institut de Neurobiologie de la Méditerranée (INMED), Aix-Marseille Université, Marseille, 13009, France.,INSERM, UMR_S 901, Marseille, 13009, France
| | - Mohamed Amri
- Laboratoire de Neurophysiologie Fonctionnelle et Pathologies, Tunis, UR11ES09, Tunisie
| | - Hélène Becq
- Institut de Neurobiologie de la Méditerranée (INMED), Aix-Marseille Université, Marseille, 13009, France.,INSERM, UMR_S 901, Marseille, 13009, France
| | - Florence Molinari
- Institut de Neurobiologie de la Méditerranée (INMED), Aix-Marseille Université, Marseille, 13009, France.,INSERM, UMR_S 901, Marseille, 13009, France
| | - Laurent Aniksztejn
- Institut de Neurobiologie de la Méditerranée (INMED), Aix-Marseille Université, Marseille, 13009, France.,INSERM, UMR_S 901, Marseille, 13009, France
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Althobaiti YS, Almalki AH, Das SC, Alshehri FS, Sari Y. Effects of repeated high-dose methamphetamine and ceftriaxone post-treatments on tissue content of dopamine and serotonin as well as glutamate and glutamine. Neurosci Lett 2016; 634:25-31. [PMID: 27702628 DOI: 10.1016/j.neulet.2016.09.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/22/2016] [Accepted: 09/30/2016] [Indexed: 01/26/2023]
Abstract
Repeated exposure to high doses of methamphetamine (METH) is known to alter several neurotransmitters in certain brain regions. Little is known about the effects of ceftriaxone (CEF), a β-lactam antibiotic, known to upregulate glutamate transporter subtype 1, post-treatment on METH-induced depletion of dopamine and serotonin (5-HT) tissue content in brain reward regions. Moreover, the effects of METH and CEF post-treatment on glutamate and glutamine tissue content are not well understood. In this study, Wistar rats were used to investigate the effects of METH and CEF post-treatment on tissue content of dopamine/5-HT and glutamate/glutamine in the nucleus accumbens (NAc) and prefrontal cortex (PFC). Rats received either saline or METH (10mg/kg, i.p. every 2h×4) followed by either saline or CEF (200mg/kg, i.p, every day×3) post-treatment. METH induced a significant depletion of dopamine and 5-HT in the NAc and PFC. Importantly, dopamine tissue content was completely restored in the NAc following CEF post-treatment. Additionally, METH caused a significant decrease in glutamate and glutamine tissue content in PFC, and this effect was attenuated by CEF post-treatment. These findings demonstrate for the first time the attenuating effects of CEF post-treatment on METH induced alterations in the tissue contents of dopamine, glutamate, and glutamine.
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Affiliation(s)
- Yusuf S Althobaiti
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH, United States
| | - Atiah H Almalki
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH, United States; University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Medicinal and Biological Chemistry, Toledo, OH, United States
| | - Sujan C Das
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH, United States; University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Medicinal and Biological Chemistry, Toledo, OH, United States
| | - Fahad S Alshehri
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH, United States
| | - Youssef Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH, United States; University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Medicinal and Biological Chemistry, Toledo, OH, United States.
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49
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Glia plasma membrane transporters: Key players in glutamatergic neurotransmission. Neurochem Int 2016; 98:46-55. [DOI: 10.1016/j.neuint.2016.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/07/2016] [Accepted: 04/06/2016] [Indexed: 12/27/2022]
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50
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Çavuş I, Romanyshyn JC, Kennard JT, Farooque P, Williamson A, Eid T, Spencer SS, Duckrow R, Dziura J, Spencer DD. Elevated basal glutamate and unchanged glutamine and GABA in refractory epilepsy: Microdialysis study of 79 patients at the yale epilepsy surgery program. Ann Neurol 2016; 80:35-45. [PMID: 27129611 DOI: 10.1002/ana.24673] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/19/2016] [Accepted: 04/17/2016] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Aberrant glutamate and γ-aminobutyric acid (GABA) neurotransmission contribute to seizure generation and the epileptic state. However, whether levels of these neurochemicals are abnormal in epileptic patients is unknown. Here, we report on interictal levels of glutamate, glutamine, and GABA in epilepsy patients at seizure onset and nonepileptic sites, cortical lesions, and from patients with poorly localized neocortical epilepsies. METHODS Subjects (n = 79) were medically refractory epilepsy patients undergoing intracranial electroencephalogram evaluation. Microdialysis probes (n = 125) coupled to depth electrodes were implanted within suspected seizure onset sites and microdialysis samples were obtained during interictal periods. Glutamate, glutamine, and GABA were measured using high-performance liquid chromatography. Probe locations were subsequently classified by consensus of expert epileptologists. RESULTS Glutamate levels were elevated in epileptogenic (p = 0.03; n = 7), nonlocalized (p < 0.001), and lesional cortical sites (p < 0.001) when compared to nonepileptogenic cortex. Glutamate was also elevated in epileptogenic (p < 0.001) compared to nonepileptogenic hippocampus. There were no statistical differences in GABA or glutamine, although GABA levels showed high variability across patients and groups. INTERPRETATION Our findings indicate that chronically elevated extracellular glutamate is a common pathological feature among epilepsies with different etiology. Contrary to our predictions, GABA and glutamine levels were not decreased in any of the measured areas. Whereas variability in GABA levels may in part be attributed to the use of GABAergic antiepileptic drugs, the stability in glutamine across patient groups indicate that extracellular glutamine levels are under tighter metabolic regulation than previously thought. Ann Neurol 2016;80:35-45.
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Affiliation(s)
- Idil Çavuş
- Department of Psychiatry, Yale School of Medicine, New Haven, CT.,Department of Neurosurgery, Yale School of Medicine, New Haven, CT
| | | | - Jeremy T Kennard
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT
| | - Pue Farooque
- Department of Neurology, Yale School of Medicine, New Haven, CT
| | - Anne Williamson
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT
| | - Tore Eid
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT.,Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT
| | - Susan S Spencer
- Department of Neurology, Yale School of Medicine, New Haven, CT
| | - Robert Duckrow
- Department of Neurology, Yale School of Medicine, New Haven, CT
| | - James Dziura
- Yale Center for Clinical Investigation Biostatistics Unit
| | - Dennis D Spencer
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT
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