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Araki S, Onishi I, Ikoma Y, Matsui K. Astrocyte switch to the hyperactive mode. Glia 2024; 72:1418-1434. [PMID: 38591259 DOI: 10.1002/glia.24537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/29/2024] [Accepted: 03/31/2024] [Indexed: 04/10/2024]
Abstract
Increasing pieces of evidence have suggested that astrocyte function has a strong influence on neuronal activity and plasticity, both in physiological and pathophysiological situations. In epilepsy, astrocytes have been shown to respond to epileptic neuronal seizures; however, whether they can act as a trigger for seizures has not been determined. Here, using the copper implantation method, spontaneous neuronal hyperactivity episodes were reliably induced during the week following implantation. With near 24-h continuous recording for over 1 week of the local field potential with in vivo electrophysiology and astrocyte cytosolic Ca2+ with the fiber photometry method, spontaneous occurrences of seizure episodes were captured. Approximately 1 day after the implantation, isolated aberrant astrocyte Ca2+ events were often observed before they were accompanied by neuronal hyperactivity, suggesting the role of astrocytes in epileptogenesis. Within a single developed episode, astrocyte Ca2+ increase preceded the neuronal hyperactivity by ~20 s, suggesting that actions originating from astrocytes could be the trigger for the occurrence of epileptic seizures. Astrocyte-specific stimulation by channelrhodopsin-2 or deep-brain direct current stimulation was capable of inducing neuronal hyperactivity. Injection of an astrocyte-specific metabolic inhibitor, fluorocitrate, was able to significantly reduce the magnitude of spontaneously occurring neuronal hyperactivity. These results suggest that astrocytes have a role in triggering individual seizures and the reciprocal astrocyte-neuron interactions likely amplify and exacerbate seizures. Therefore, future epilepsy treatment could be targeted at astrocytes to achieve epilepsy control.
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Affiliation(s)
- Shun Araki
- Super-network Brain Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Ichinosuke Onishi
- Super-network Brain Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Yoko Ikoma
- Super-network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Ko Matsui
- Super-network Brain Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
- Super-network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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2
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Wang HY, Takagi H, Stoney PN, Echeverria A, Kuhn B, Hsu KS, Takahashi T. Anoxia-induced hippocampal LTP is regeneratively produced by glutamate and nitric oxide from the neuro-glial-endothelial axis. iScience 2024; 27:109515. [PMID: 38591010 PMCID: PMC11000013 DOI: 10.1016/j.isci.2024.109515] [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: 10/23/2023] [Revised: 01/17/2024] [Accepted: 03/14/2024] [Indexed: 04/10/2024] Open
Abstract
Transient anoxia causes amnesia and neuronal death. This is attributed to enhanced glutamate release and modeled as anoxia-induced long-term potentiation (aLTP). aLTP is mediated by glutamate receptors and nitric oxide (·NO) and occludes stimulation-induced LTP. We identified a signaling cascade downstream of ·NO leading to glutamate release and a glutamate-·NO loop regeneratively boosting aLTP. aLTP in entothelial ·NO synthase (eNOS)-knockout mice and blocking neuronal NOS (nNOS) activity suggested that both nNOS and eNOS contribute to aLTP. Immunostaining result showed that eNOS is predominantly expressed in vascular endothelia. Transient anoxia induced a long-lasting Ca2+ elevation in astrocytes that mirrored aLTP. Blocking astrocyte metabolism or depletion of the NMDA receptor ligand D-serine abolished eNOS-dependent aLTP, suggesting that astrocytic Ca2+ elevation stimulates D-serine release from endfeet to endothelia, thereby releasing ·NO synthesized by eNOS. Thus, the neuro-glial-endothelial axis is involved in long-term enhancement of glutamate release after transient anoxia.
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Affiliation(s)
- Han-Ying Wang
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
- Academia Sinica, Institute of Biomedical Sciences, Taipei 115, Taiwan
| | - Hiroshi Takagi
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
- Department of Neurosurgery, Graduate School of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan
| | - Patrick N. Stoney
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Anai Echeverria
- Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Bernd Kuhn
- Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Tomoyuki Takahashi
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
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3
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Karger G, Berger J, Dringen R. Modulation of Cellular Levels of Adenosine Phosphates and Creatine Phosphate in Cultured Primary Astrocytes. Neurochem Res 2024; 49:402-414. [PMID: 37855866 PMCID: PMC10787699 DOI: 10.1007/s11064-023-04039-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 10/20/2023]
Abstract
Adenosine triphosphate (ATP) is the main energy currency of all cells, while creatine phosphate (CrP) is considered as a buffer of high energy-bond phosphate that facilitates rapid regeneration of ATP from adenosine diphosphate (ADP). Astrocyte-rich primary cultures contain ATP, ADP and adenosine monophosphate (AMP) in average specific contents of 36.0 ± 6.4 nmol/mg, 2.9 ± 2.1 nmol/mg and 1.7 ± 2.1 nmol/mg, respectively, which establish an adenylate energy charge of 0.92 ± 0.04. The average specific cellular CrP level was found to be 25.9 ± 10.8 nmol/mg and the CrP/ATP ratio was 0.74 ± 0.28. The specific cellular CrP content, but not the ATP content, declined with the age of the culture. Absence of fetal calf serum for 24 h caused a partial loss in the cellular contents of both CrP and ATP, while application of creatine for 24 h doubled the cellular CrP content and the CrP/ATP ratio, but did not affect ATP levels. In glucose-deprived astrocytes, the high cellular ATP and CrP contents were rapidly depleted within minutes after application of the glycolysis inhibitor 2-deoxyglucose and the respiratory chain inhibitor antimycin A. For those conditions, the decline in CrP levels always preceded that of ATP contents. In contrast, incubation of glucose-fed astrocytes for up to 30 min with antimycin A had little effect on the high cellular ATP content, while the CrP level was significantly lowered. These data demonstrate the importance of cellular CrP for maintaining a high cellular ATP content in astrocytes during episodes of impaired ATP regeneration.
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Affiliation(s)
- Gabriele Karger
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Julius Berger
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
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4
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Zhang W, Yin J, Gao BY, Lu X, Duan YJ, Liu XY, Li MZ, Jiang S. Inhibition of astroglial hemichannels ameliorates infrasonic noise induced short-term learning and memory impairment. BEHAVIORAL AND BRAIN FUNCTIONS : BBF 2023; 19:23. [PMID: 38110991 PMCID: PMC10726613 DOI: 10.1186/s12993-023-00226-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 12/13/2023] [Indexed: 12/20/2023]
Abstract
As a kind of environmental noise, infrasonic noise has negative effects on various human organs. To date, research has shown that infrasound impairs cognitive function, especially the ability for learning and memory. Previously, we demonstrated that impaired learning and memory induced by infrasound was closely related with glia activation; however, the underlying mechanisms remain unclear. Connexin 43 hemichannels (Cx43 HCs), which are mainly expressed in hippocampal astrocytes, are activated under pathological conditions, lending support to the hypothesis that Cx43 HCs might function in the impaired learning and memory induced by infrasound. This study revealed that that blocking hippocampal Cx43 HCs or downregulating hippocampal Cx43 expression significantly alleviated impaired learning and memory induced by infrasound. We also observed that infrasound exposure led to the abundant release of glutamate and ATP through Cx43 HCs. In addition, the abundant release of glutamate and ATP depended on proinflammatory cytokines. Our finds suggested that the enhanced release of ATP and glutamate by astroglial Cx43 HCs may be involved in the learning and memory deficits caused by infrasound exposure.
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Affiliation(s)
- Wei Zhang
- Teaching and Evaluation Center of Air Force Medical University, Xi'an, 710032, China
| | - Jue Yin
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Bei-Yao Gao
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Xi Lu
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Ya-Jing Duan
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Xu-Yan Liu
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Ming-Zhen Li
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China
| | - Shan Jiang
- Department of Rehabilitation Medicine, The China-Japan Friendship Hospital, No.2 Ying Hua Yuan East Street, Beijing, 100029, People's Republic of China.
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Díaz F, Aguilar F, Wellmann M, Martorell A, González-Arancibia C, Chacana-Véliz L, Negrón-Oyarzo I, Chávez AE, Fuenzalida M, Nualart F, Sotomayor-Zárate R, Bonansco C. Enhanced Astrocyte Activity and Excitatory Synaptic Function in the Hippocampus of Pentylenetetrazole Kindling Model of Epilepsy. Int J Mol Sci 2023; 24:14506. [PMID: 37833953 PMCID: PMC10572460 DOI: 10.3390/ijms241914506] [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: 08/29/2023] [Revised: 09/12/2023] [Accepted: 09/17/2023] [Indexed: 10/15/2023] Open
Abstract
Epilepsy is a chronic condition characterized by recurrent spontaneous seizures. The interaction between astrocytes and neurons has been suggested to play a role in the abnormal neuronal activity observed in epilepsy. However, the exact way astrocytes influence neuronal activity in the epileptogenic brain remains unclear. Here, using the PTZ-induced kindling mouse model, we evaluated the interaction between astrocyte and synaptic function by measuring astrocytic Ca2+ activity, neuronal excitability, and the excitatory/inhibitory balance in the hippocampus. Compared to control mice, hippocampal slices from PTZ-kindled mice displayed an increase in glial fibrillary acidic protein (GFAP) levels and an abnormal pattern of intracellular Ca2+-oscillations, characterized by an increased frequency of prolonged spontaneous transients. PTZ-kindled hippocampal slices also showed an increase in the E/I ratio towards excitation, likely resulting from an augmented release probability of excitatory inputs without affecting inhibitory synapses. Notably, the alterations in the release probability seen in PTZ-kindled slices can be recovered by reducing astrocyte hyperactivity with the reversible toxin fluorocitrate. This suggests that astroglial hyper-reactivity enhances excitatory synaptic transmission, thereby impacting the E/I balance in the hippocampus. Altogether, our findings support the notion that abnormal astrocyte-neuron interactions are pivotal mechanisms in epileptogenesis.
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Affiliation(s)
- Franco Díaz
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
- Escuela de Ciencias de la Salud, Universidad Viña del Mar, Viña del Mar 2580022, Chile
- Programa de Magíster en Ciencias Biológicas mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Freddy Aguilar
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
- Programa de Magíster en Ciencias Biológicas mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Mario Wellmann
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
- Programa de Magíster en Ciencias Biológicas mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Andrés Martorell
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
- Programa de Magíster en Ciencias Biológicas mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
- Escuela de Fonoaudiología, Facultad de Salud, Universidad Santo Tomás, Viña del Mar 2561780, Chile
| | - Camila González-Arancibia
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
| | - Lorena Chacana-Véliz
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
| | - Ignacio Negrón-Oyarzo
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
| | - Andrés E. Chávez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile;
| | - Marco Fuenzalida
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
| | - Francisco Nualart
- Laboratory of Neurobiology and Stem Cells, NeuroCellT, Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion, Concepción 4070386, Chile;
- Center for Advanced Microscopy CMA BIOBIO, Faculty of Biological Sciences, University of Concepcion, Concepción 4070386, Chile
| | - Ramón Sotomayor-Zárate
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
| | - Christian Bonansco
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (F.D.); (F.A.); (M.W.); (A.M.); (C.G.-A.); (L.C.-V.); (I.N.-O.); (M.F.)
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Hastings MH, Brancaccio M, Gonzalez-Aponte MF, Herzog ED. Circadian Rhythms and Astrocytes: The Good, the Bad, and the Ugly. Annu Rev Neurosci 2023; 46:123-143. [PMID: 36854316 PMCID: PMC10381027 DOI: 10.1146/annurev-neuro-100322-112249] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
This review explores the interface between circadian timekeeping and the regulation of brain function by astrocytes. Although astrocytes regulate neuronal activity across many time domains, their cell-autonomous circadian clocks exert a particular role in controlling longer-term oscillations of brain function: the maintenance of sleep states and the circadian ordering of sleep and wakefulness. This is most evident in the central circadian pacemaker, the suprachiasmatic nucleus, where the molecular clock of astrocytes suffices to drive daily cycles of neuronal activity and behavior. In Alzheimer's disease, sleep impairments accompany cognitive decline. In mouse models of the disease, circadian disturbances accelerate astroglial activation and other brain pathologies, suggesting that daily functions in astrocytes protect neuronal homeostasis. In brain cancer, treatment in the morning has been associated with prolonged survival, and gliomas have daily rhythms in gene expression and drug sensitivity. Thus, circadian time is fast becoming critical to elucidating reciprocal astrocytic-neuronal interactions in health and disease.
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Affiliation(s)
- Michael H Hastings
- Division of Neurobiology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom;
| | - Marco Brancaccio
- UK Dementia Research Institute and Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Maria F Gonzalez-Aponte
- Department of Biology, Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri, USA;
| | - Erik D Herzog
- Department of Biology, Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri, USA;
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Ma W, Si T, Wang Z, Wen P, Zhu Z, Liu Q, Wang J, Xu F, Li Q. Astrocytic α4-containing nAChR signaling in the hippocampus governs the formation of temporal association memory. Cell Rep 2023; 42:112674. [PMID: 37352098 DOI: 10.1016/j.celrep.2023.112674] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 03/24/2023] [Accepted: 06/06/2023] [Indexed: 06/25/2023] Open
Abstract
Everyday episodic memories involve linking together related events that are temporally separated. However, the mechanisms of forming this temporal association have remained unclear. Here, using astrocyte-specific manipulations, we show that potentiating astrocyte Ca2+ signaling in the hippocampal cornu ammonis 1 (CA1) enhances the strength of such temporal association, in parallel with long-term potentiation (LTP) enhancement of temporoammonic pathway to CA1, whereas attenuation of astrocyte Ca2+ signaling has the opposite effect. Moreover, we identify that these effects are mediated by astrocytic α4 subunit-containing nicotinic acetylcholine receptors (α4-nAChRs) via mechanisms involving NMDAR co-agonist supply. Finally, astrocytic α4-nAChRs underlie the cognitive enhancer nicotine's physiological effects. Together, these findings highlight the importance of astrocyte Ca2+ signaling in cognitive behavior and reveal a mechanism in governing the temporal association of episodic memory formation that operates through α4-nAChRs on hippocampal astrocytes.
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Affiliation(s)
- Wenyu Ma
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tengxiao Si
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zan Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pengjie Wen
- Shenzhen Key Laboratory of Viral Vectors for Biomedicine, NMPA Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Zhenxiang Zhu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; Shenzhen Key Laboratory of Viral Vectors for Biomedicine, NMPA Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qing Liu
- Shenzhen Key Laboratory of Viral Vectors for Biomedicine, NMPA Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jie Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fuqiang Xu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; Shenzhen Key Laboratory of Viral Vectors for Biomedicine, NMPA Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal Products, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Qin Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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8
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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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9
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Harders AR, Arend C, Denieffe SC, Berger J, Dringen R. Endogenous Energy Stores Maintain a High ATP Concentration for Hours in Glucose-Depleted Cultured Primary Rat Astrocytes. Neurochem Res 2023; 48:2241-2252. [PMID: 36914795 PMCID: PMC10182151 DOI: 10.1007/s11064-023-03903-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 03/16/2023]
Abstract
Adenosine triphosphate (ATP) is the central energy currency of all cells. Cultured primary rat astrocytes contain a specific cellular ATP content of 27.9 ± 4.7 nmol/mg. During incubation in a glucose- and amino acid-free incubation buffer, this high cellular ATP content was maintained for at least 6 h, while within 24 h the levels of ATP declined to around 30% of the initial value without compromising cell viability. In contrast, cells exposed to 1 mM and 5 mM glucose maintained the initial high cellular ATP content for 24 and 72 h, respectively. The loss in cellular ATP content observed during a 24 h glucose-deprivation was fully prevented by the presence of glucose, fructose or mannose as well as by the mitochondrial substrates lactate, pyruvate, β-hydroxybutyrate or acetate. The high initial specific ATP content in glucose-starved astrocytes, was almost completely abolished within 30 min after application of the respiratory chain inhibitor antimycin A or the mitochondrial uncoupler BAM-15, while these inhibitors lowered in glucose-fed cells the ATP content only to 60% (BAM-15) and 40% (antimycin A) within 5 h. Inhibition of the mitochondrial pyruvate carrier by UK5099 alone or of mitochondrial fatty acid uptake by etomoxir alone hardly affected the high ATP content of glucose-deprived astrocytes during an incubation for 8 h, while the co-application of both inhibitors depleted cellular ATP levels almost completely within 5 h. These data underline the importance of mitochondrial metabolism for the ATP regeneration of astrocytes and demonstrate that the mitochondrial oxidation of pyruvate and fatty acids strongly contributes to the maintenance of a high ATP concentration in glucose-deprived astrocytes.
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Affiliation(s)
- Antonia Regina Harders
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Christian Arend
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Sadhbh Cynth Denieffe
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Julius Berger
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany. .,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
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10
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Vaccari-Cardoso B, Antipina M, Teschemacher AG, Kasparov S. Lactate-Mediated Signaling in the Brain-An Update. Brain Sci 2022; 13:brainsci13010049. [PMID: 36672031 PMCID: PMC9856103 DOI: 10.3390/brainsci13010049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/15/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022] Open
Abstract
Lactate is a universal metabolite produced and released by all cells in the body. Traditionally it was viewed as energy currency that is generated from pyruvate at the end of the glycolytic pathway and sent into the extracellular space for other cells to take up and consume. In the brain, such a mechanism was postulated to operate between astrocytes and neurons many years ago. Later, the discovery of lactate receptors opened yet another chapter in the quest to understand lactate actions. Other ideas, such as modulation of NMDA receptors were also proposed. Up to this day, we still do not have a consensus view on the relevance of any of these mechanisms to brain functions or their contribution to human or animal physiology. While the field develops new ideas, in this brief review we analyze some recently published studies in order to focus on some unresolved controversies and highlight the limitations that need to be addressed in future work. Clearly, only by using similar and overlapping methods, cross-referencing experiments, and perhaps collaborative efforts, we can finally understand what the role of lactate in the brain is and why this ubiquitous molecule is so important.
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Affiliation(s)
- Barbara Vaccari-Cardoso
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Maria Antipina
- MEDBIO, Immanuel Kant Baltic Federal University, Universitetskaya Str., 2, 236041 Kaliningrad, Russia
| | - Anja G. Teschemacher
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Sergey Kasparov
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
- Correspondence:
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11
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Schaible HG, König C, Ebersberger A. Spinal pain processing in arthritis: Neuron and glia (inter)actions. J Neurochem 2022. [PMID: 36520021 DOI: 10.1111/jnc.15742] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022]
Abstract
Diseases of joints are among the most frequent causes of chronic pain. In the course of joint diseases, the peripheral and the central nociceptive system develop persistent hyperexcitability (peripheral and central sensitization). This review addresses the mechanisms of spinal sensitization evoked by arthritis. Electrophysiological recordings in anesthetized rats from spinal cord neurons with knee input in a model of acute arthritis showed that acute spinal sensitization is dependent on spinal glutamate receptors (AMPA, NMDA, and metabotropic glutamate receptors) and supported by spinal actions of neuropeptides such as neurokinins and CGRP, by prostaglandins, and by proinflammatory cytokines. In several chronic arthritis models (including immune-mediated arthritis and osteoarthritis) spinal glia activation was observed to be coincident with behavioral mechanical hyperalgesia which was attenuated or prevented by intrathecal application of minocycline, fluorocitrate, and pentoxyfylline. Some studies identified specific pathways of micro- and astroglia activation such as the purinoceptor- (P2 X7 -) cathepsin S/CX3 CR1 pathway, the mobility group box-1 protein (HMGB1), and toll-like receptor 4 (TLR4) activation, spinal NFκB/p65 activation and others. The spinal cytokines TNF, interleukin-6, interleukin-1β, and others form a functional spinal network characterized by an interaction between neurons and glia cells which is required for spinal sensitization. Neutralization of spinal cytokines by intrathecal interventions attenuates mechanical hyperalgesia. This effect may in part result from local suppression of spinal sensitization and in part from efferent effects which attenuate the inflammatory process in the joint. In summary, arthritis evokes significant spinal hyperexcitability which is likely to contribute to the phenotype of arthritis pain in patients.
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Affiliation(s)
- Hans-Georg Schaible
- Institute of Physiology 1/Neurophysiology, Jena University Hospital, Friedrich-Schiller-University of Jena, Jena, Germany
| | - Christian König
- Institute of Physiology 1/Neurophysiology, Jena University Hospital, Friedrich-Schiller-University of Jena, Jena, Germany
| | - Andrea Ebersberger
- Institute of Physiology 1/Neurophysiology, Jena University Hospital, Friedrich-Schiller-University of Jena, Jena, Germany
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12
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Vizuete AFK, Fróes F, Seady M, Zanotto C, Bobermin LD, Roginski AC, Wajner M, Quincozes-Santos A, Gonçalves CA. Early effects of LPS-induced neuroinflammation on the rat hippocampal glycolytic pathway. J Neuroinflammation 2022; 19:255. [PMID: 36221097 PMCID: PMC9552490 DOI: 10.1186/s12974-022-02612-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/27/2022] [Indexed: 11/10/2022] Open
Abstract
Neuroinflammation is a common feature during the development of neurological disorders and neurodegenerative diseases, where glial cells, such as microglia and astrocytes, play key roles in the activation and maintenance of inflammatory responses in the central nervous system. Neuroinflammation is now known to involve a neurometabolic shift, in addition to an increase in energy consumption. We used two approaches (in vivo and ex vivo) to evaluate the effects of lipopolysaccharide (LPS)-induced neuroinflammation on neurometabolic reprogramming, and on the modulation of the glycolytic pathway during the neuroinflammatory response. For this, we investigated inflammatory cytokines and receptors in the rat hippocampus, as well as markers of glial reactivity. Mitochondrial respirometry and the glycolytic pathway were evaluated by multiple parameters, including enzymatic activity, gene expression and regulation by protein kinases. Metabolic (e.g., metformin, 3PO, oxamic acid, fluorocitrate) and inflammatory (e.g., minocycline, MCC950, arundic acid) inhibitors were used in ex vivo hippocampal slices. The induction of early inflammatory changes by LPS (both in vivo and ex vivo) enhanced glycolytic parameters, such as glucose uptake, PFK1 activity and lactate release. This increased glucose consumption was independent of the energy expenditure for glutamate uptake, which was in fact diverted for the maintenance of the immune response. Accordingly, inhibitors of the glycolytic pathway and Krebs cycle reverted neuroinflammation (reducing IL-1β and S100B) and the changes in glycolytic parameters induced by LPS in acute hippocampal slices. Moreover, the inhibition of S100B, a protein predominantly synthesized and secreted by astrocytes, inhibition of microglia activation and abrogation of NLRP3 inflammasome assembly confirmed the role of neuroinflammation in the upregulation of glycolysis in the hippocampus. Our data indicate a neurometabolic glycolytic shift, induced by inflammatory activation, as well as a central and integrative role of astrocytes, and suggest that interference in the control of neurometabolism may be a promising strategy for downregulating neuroinflammation and consequently for diminishing negative neurological outcomes.
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Affiliation(s)
- Adriana Fernanda K Vizuete
- Laboratory of Calcium-Binding Proteins in the CNS, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul (UFRGS), Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Zip Code: 90035-003, Brazil. .,Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil.
| | - Fernanda Fróes
- Laboratory of Calcium-Binding Proteins in the CNS, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul (UFRGS), Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Zip Code: 90035-003, Brazil.,Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Marina Seady
- Laboratory of Calcium-Binding Proteins in the CNS, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul (UFRGS), Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Zip Code: 90035-003, Brazil.,Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Caroline Zanotto
- Laboratory of Calcium-Binding Proteins in the CNS, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul (UFRGS), Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Zip Code: 90035-003, Brazil.,Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Larissa Daniele Bobermin
- Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Ana Cristina Roginski
- Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Moacir Wajner
- Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil.,Department of Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil.,Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - André Quincozes-Santos
- Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil.,Department of Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
| | - Carlos Alberto Gonçalves
- Laboratory of Calcium-Binding Proteins in the CNS, Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul (UFRGS), Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Zip Code: 90035-003, Brazil.,Pos Graduate Program in Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil.,Department of Biochemistry, Institute of Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil
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13
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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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14
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Malfunction of astrocyte and cholinergic input is involved in postoperative impairment of hippocampal synaptic plasticity and cognitive function. Neuropharmacology 2022; 217:109191. [PMID: 35835213 DOI: 10.1016/j.neuropharm.2022.109191] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 06/04/2022] [Accepted: 07/07/2022] [Indexed: 12/28/2022]
Abstract
Postoperative delirium (POD) occurs in a few days after major surgery under general anesthesia and may cause serious health problems. However, effective intervention and treatment remain unavailable because the underlying mechanisms have far been elucidated. In the present study, we explored the role of the malfunctioned astrocytes in POD. Our results showed that mice with tibia fracture displayed spatial and temporal memory impairments, reduced LTP, and activated astrocytes in the hippocampus in early postoperative stage. Using electrophysiological and Ca2+ imaging techniques in hippocampal slices, we demonstrated the malfunctions of astrocytes in surgery mice: depolarized resting membrane potential, higher membrane conductance and capacitance, and attenuated Ca2+ elevation in response to external stimulation. The degraded calcium signaling in hippocampal astrocytes in surgery mice was restored by correcting the diminution of acetylcholine release with galantamine. Furthermore, pharmacologically blocking astrocyte activation with fluorocitrate and enhancing cholinergic inputs with galantamine normalized hippocampal LTP in surgery mice. Finally, inhibition of astrocyte activation with fluorocitrate in the hippocampus improved cognitive function in surgery mice. Therefore, the prevention of astrocyte activation may be a valuable strategy for the intervention of cognitive dysfunction in POD, and acetylcholine receptors may be valid drug targets for this purpose.
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15
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Menyhárt Á, Frank R, Farkas AE, Süle Z, Varga VÉ, Nyúl-Tóth Á, Meiller A, Ivánkovits-Kiss O, Lemale CL, Szabó Í, Tóth R, Zölei-Szénási D, Woitzik J, Marinesco S, Krizbai IA, Bari F, Dreier JP, Farkas E. Malignant astrocyte swelling and impaired glutamate clearance drive the expansion of injurious spreading depolarization foci. J Cereb Blood Flow Metab 2022; 42:584-599. [PMID: 34427145 PMCID: PMC8943616 DOI: 10.1177/0271678x211040056] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Spreading depolarizations (SDs) indicate injury progression and predict worse clinical outcome in acute brain injury. We demonstrate in rodents that acute brain swelling upon cerebral ischemia impairs astroglial glutamate clearance and increases the tissue area invaded by SD. The cytotoxic extracellular glutamate accumulation (>15 µM) predisposes an extensive bulk of tissue (4-5 mm2) for a yet undescribed simultaneous depolarization (SiD). We confirm in rat brain slices exposed to osmotic stress that SiD is the pathological expansion of prior punctual SD foci (0.5-1 mm2), is associated with astrocyte swelling, and triggers oncotic neuron death. The blockade of astrocytic aquaporin-4 channels and Na+/K+/Cl- co-transporters, or volume-regulated anion channels mitigated slice edema, extracellular glutamate accumulation (<10 µM) and SiD occurrence. Reversal of slice swelling by hyperosmotic mannitol counteracted glutamate accumulation and prevented SiD. In contrast, inhibition of glial metabolism or inhibition of astrocyte glutamate transporters reproduced the SiD phenotype. Finally, we show in the rodent water intoxication model of cytotoxic edema that astrocyte swelling and altered astrocyte calcium waves are central in the evolution of SiD. We discuss our results in the light of evidence for SiD in the human cortex. Our results emphasize the need of preventive osmotherapy in acute brain injury.
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Affiliation(s)
- Ákos Menyhárt
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Rita Frank
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Attila E Farkas
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Zoltán Süle
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória É Varga
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Ádám Nyúl-Tóth
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Anne Meiller
- Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5292, University Claude Bernard Lyon I, Lyon, France
| | - Orsolya Ivánkovits-Kiss
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Coline L Lemale
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Írisz Szabó
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Réka Tóth
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Dániel Zölei-Szénási
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Johannes Woitzik
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Stephane Marinesco
- Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5292, University Claude Bernard Lyon I, Lyon, France
| | - István A Krizbai
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Institute of Life Sciences, Vasile Goldis Western University, Arad, Romania
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Jens P Dreier
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Eszter Farkas
- HCEMM-USZ Cerebral Blood Flow and Metabolism Research Group, Szeged, Hungary.,Department of Cell Biology and Molecular Medicine, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged,Szeged, Hungary
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16
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Nikkar R, Esmaeili-Bandboni A, Badrikoohi M, Babaei P. Effects of inhibiting astrocytes and BET/BRD4 chromatin reader on spatial memory and synaptic proteins in rats with Alzheimer's disease. Metab Brain Dis 2022; 37:1119-1131. [PMID: 35244824 DOI: 10.1007/s11011-022-00940-7] [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: 12/06/2021] [Accepted: 02/21/2022] [Indexed: 10/18/2022]
Abstract
Communication between astrocytes and neurons has a profound effect on the pathophysiology of Alzheimer's disease (AD). Astrocytes regulate homeostasis and increase synaptic plasticity in physiological situations, however, they become activated during the progression of AD. Whether or not these reactions are supportive or detrimental for the central nervous system have not been understood yet. Considering epigenetic regulation of neuroinflammatory genes by chromatin readers, particularly bromodomain and extraterminal domain (BET) family, here we examined the effect of chronic co-inhibition of astrocytes metabolism (with fluorocitrate) and also BRD4 (with JQ1) on cognition deficit at early stages of AD. Forty adult male Wistar rats underwent stereotaxic cannulation for inducing AD by intrahippocampal injection of Aβ1-42 (4 μg/8 μl/rat). Then animals were divided into five groups of Saline+DMSO, Aβ + saline+DMSO, Aβ + JQ1, Aβ + FC (fluorocitrate), and Aβ + JQ1 + FC and received the related treatments. Two weeks later, spatial memory was recorded by Morris Water Maze (MWM), and the levels of phosphorylated cyclic-AMP response element binding protein (CREB), postsynaptic density 95 (PSD95), synaptophysin (SYP), and tumor necrosis factor-alpha (TNF-α) were measured in the hippocampus by western blotting and RT-qPCR. Administration of JQ1 significantly improved both acquisition and retrieval of spatial memory, which were evident by decreased escape latency and increased total time spent (TTS) in target quadrant, and significant rise in p-CREB, PSD95, and synaptophysin compared with Aβ + saline+DMSO group. In contrast, both groups receiving FC demonstrated memory decline, and reduction in p-CREB, PSD95 and synaptophysin in parallel with increase in TNF-α. Our data indicate that chronic inhibition of BRD4 significantly restores memory impaired by amyloid β partly via CREB signaling and upregulating synaptic proteins of PSD95 and synaptophysin. However, inhibition of astrocytes nullifies the memory-boosting effects of JQ1 and reduces CREB/PSD95/synaptophysin levels in hippocampus.
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Affiliation(s)
- Rastin Nikkar
- Cellular &Molecular Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
- Neuroscience Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
| | - Aghil Esmaeili-Bandboni
- Department of Medical Genetics, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
- Medical Biotechnology Research Center, School of Paramedicine, Guilan University of Medical Sciences, Rasht, Iran
| | - Mahshid Badrikoohi
- Cellular &Molecular Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
- Department of Physiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
| | - Parvin Babaei
- Cellular &Molecular Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
- Neuroscience Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
- Department of Physiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
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17
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Salcedo C, Andersen JV, Vinten KT, Pinborg LH, Waagepetersen HS, Freude KK, Aldana BI. Functional Metabolic Mapping Reveals Highly Active Branched-Chain Amino Acid Metabolism in Human Astrocytes, Which Is Impaired in iPSC-Derived Astrocytes in Alzheimer's Disease. Front Aging Neurosci 2021; 13:736580. [PMID: 34603012 PMCID: PMC8484639 DOI: 10.3389/fnagi.2021.736580] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/04/2021] [Indexed: 01/04/2023] Open
Abstract
The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are important nitrogen donors for synthesis of glutamate, the main excitatory neurotransmitter in the brain. The glutamate carbon skeleton originates from the tricarboxylic acid (TCA) cycle intermediate α-ketoglutarate, while the amino group is derived from nitrogen donors such as the BCAAs. Disturbances in neurotransmitter homeostasis, mainly of glutamate, are strongly implicated in the pathophysiology of Alzheimer's disease (AD). The divergent BCAA metabolism in different cell types of the human brain is poorly understood, and so is the involvement of astrocytic and neuronal BCAA metabolism in AD. The goal of this study is to provide the first functional characterization of BCAA metabolism in human brain tissue and to investigate BCAA metabolism in AD pathophysiology using astrocytes and neurons derived from human-induced pluripotent stem cells (hiPSCs). Mapping of BCAA metabolism was performed using mass spectrometry and enriched [15N] and [13C] isotopes of leucine, isoleucine, and valine in acutely isolated slices of surgically resected cerebral cortical tissue from human brain and in hiPSC-derived brain cells carrying mutations in either amyloid precursor protein (APP) or presenilin-1 (PSEN-1). We revealed that both human astrocytes of acutely isolated cerebral cortical slices and hiPSC-derived astrocytes were capable of oxidatively metabolizing the carbon skeleton of BCAAs, particularly to support glutamine synthesis. Interestingly, hiPSC-derived astrocytes with APP and PSEN-1 mutations exhibited decreased amino acid synthesis of glutamate, glutamine, and aspartate derived from leucine metabolism. These results clearly demonstrate that there is an active BCAA metabolism in human astrocytes, and that leucine metabolism is selectively impaired in astrocytes derived from the hiPSC models of AD. This impairment in astrocytic BCAA metabolism may contribute to neurotransmitter and energetic imbalances in the AD brain.
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Affiliation(s)
- Claudia Salcedo
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kasper Tore Vinten
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars H Pinborg
- Epilepsy Clinic and Neurobiology Research Unit, Copenhagen University Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristine K Freude
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Zhao J, Blaeser AS, Levy D. Astrocytes mediate migraine-related intracranial meningeal mechanical hypersensitivity. Pain 2021; 162:2386-2396. [PMID: 34448752 PMCID: PMC8406410 DOI: 10.1097/j.pain.0000000000002229] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/26/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT The genesis of the headache phase in migraine with aura is thought to be mediated by cortical spreading depression (CSD) and the subsequent activation and sensitization of primary afferent neurons that innervate the intracranial meninges and their related large vessels. Yet, the exact mechanisms underlying this peripheral meningeal nociceptive response remain poorly understood. We investigated the relative contribution of cortical astrocytes to CSD-evoked meningeal nociception using extracellular single-unit recording of meningeal afferent activity and 2-photon imaging of cortical astrocyte calcium activity, in combination with 2 pharmacological approaches to inhibit astrocytic function. We found that fluoroacetate and l-α-aminoadipate, which inhibit astrocytes through distinct mechanisms, suppressed CSD-evoked afferent mechanical sensitization, but did not affect afferent activation. Pharmacological inhibition of astrocytic function, which ameliorated meningeal afferents' sensitization, reduced basal astrocyte calcium activity but had a minimal effect on the astrocytic calcium wave during CSD. We propose that calcium-independent signaling in cortical astrocytes plays an important role in driving the sensitization of meningeal afferents and the ensuing intracranial mechanical hypersensitivity in migraine with aura.
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Affiliation(s)
- Jun Zhao
- Departments of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Andrew S. Blaeser
- Departments of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Dan Levy
- Departments of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
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19
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Wu L, Ji NN, Wang H, Hua JY, Sun GL, Chen PP, Hua R, Zhang YM. Domino Effect of Interleukin-15 and CD8 T-Cell-Mediated Neuronal Apoptosis in Experimental Traumatic Brain Injury. J Neurotrauma 2021; 38:1450-1463. [PMID: 30430911 DOI: 10.1089/neu.2017.5607] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The effects of local factors on activation of immune cells infiltrating the central nervous system (CNS) in a rat model of traumatic brain injury (TBI) remain elusive. The cytokine, interleukin (IL)-15, is crucial for development and activation of CD8 T lymphocytes, a prominent lymphocytic population present in TBI lesions. We investigated whether IL-15 originates from astrocytes and whether IL-15 can evoke the CD8 T-lymphocyte response in TBI. We observed that astrocytes were activated in a rat model of TBI and that IL-15 was overexpressed on the surface of astrocytes. Further, CD8 T lymphocytes infiltrating TBI lesions colocalized with IL-15-expressing astrocytes. Activated CD8 T lymphocytes released granzyme B (Gra-b), which, in turn, activated caspase-3-induced poly(ADP-ribose) polymerase cleavage and, ultimately, neuronal apoptosis. Conversely, inhibition of astrocyte activation by pre-treatment with the specific inhibitor, fluorocitrate (FC), that reduces carbon flux through the Krebs cycle in astrocytes resulted in improved neurological function and memory. FC pre-treatment was also associated with downregulated IL-15 expression and CD8 T-cell activation as well as decreased levels of neuronal apoptosis, suggesting that IL-15 initiated a domino effect toward apoptosis. In contrast, rats pre-treated with recombinant rat IL-15 showed upregulated CD8 T-cell numbers and Gra-b levels, in addition to induction of neuronal apoptosis. Together, our results indicated that IL-15 could induce neuronal apoptosis by enhancing CD8 T-cell function in a rat model of TBI.
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Affiliation(s)
- Liang Wu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Department of Anesthesiology, Xuzhou Municipal Hospital Affiliated with Xuzhou Medical University, Xuzhou, China
| | - Ning-Ning Ji
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Department of Anesthesiology, Xuzhou Municipal Hospital Affiliated with Xuzhou Medical University, Xuzhou, China
| | - Hang Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Jing-Yu Hua
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Guo-Lin Sun
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Pan-Pan Chen
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Rong Hua
- Faculty of Emergency Rescue Medicine, Xuzhou Medical University, Xuzhou, China.,Emergency Center of the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Yong-Mei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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20
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Onimaru H, Yazawa I, Takeda K, Fukushi I, Okada Y. Calcium Imaging Analysis of Cellular Responses to Hypercapnia and Hypoxia in the NTS of Newborn Rat Brainstem Preparation. Front Physiol 2021; 12:645904. [PMID: 33841182 PMCID: PMC8027497 DOI: 10.3389/fphys.2021.645904] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 03/08/2021] [Indexed: 01/13/2023] Open
Abstract
It is supposed that the nucleus of the solitary tract (NTS) in the dorsal medulla includes gas sensor cells responsive to hypercapnia or hypoxia in the central nervous system. In the present study, we analyzed cellular responses to hypercapnia and hypoxia in the NTS region of newborn rat in vitro preparation. The brainstem and spinal cord were isolated from newborn rat (P0-P4) and were transversely cut at the level of the rostral area postrema. To detect cellular responses, calcium indicator Oregon Green was pressure-injected into the NTS just beneath the cut surface of either the caudal or rostral block of the medulla, and the preparation was superfused with artificial cerebrospinal fluid (25–26°C). We examined cellular responses initially to hypercapnic stimulation (to 8% CO2 from 2% CO2) and then to hypoxic stimulation (to 0% O2 from 95% O2 at 5% CO2). We tested these responses in standard solution and in two different synapse blockade solutions: (1) cocktail blockers solution including bicuculline, strychnine, NBQX and MK-801 or (2) TTX solution. At the end of the experiments, the superfusate potassium concentration was lowered to 0.2 from 3 mM to classify recorded cells into neurons and astrocytes. Excitation of cells was detected as changes of fluorescence intensity with a confocal calcium imaging system. In the synaptic blockade solutions (cocktail or TTX solution), 7.6 and 8% of the NTS cells responded to hypercapnic and hypoxic stimulation, respectively, and approximately 2% of them responded to both stimulations. Some of these cells responded to low K+, and they were classified into astrocytes comprising 43% hypercapnia-sensitive cells, 56% hypoxia-sensitive cells and 54% of both stimulation-sensitive cells. Of note, 49% of the putative astrocytes identified by low K+ stimulation were sensitive to hypercapnia, hypoxia or both. In the presence of a glia preferential blocker, 5 mM fluoroacetate (plus 0.5 μM TTX), the percentage of hypoxia-sensitive cells was significantly reduced compared to those of all other conditions. This is the first study to reveal that the NTS includes hypercapnia and hypoxia dual-sensitive cells. These results suggest that astrocytes in the NTS region could act as a central gas sensor.
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Affiliation(s)
- Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
| | - Itaru Yazawa
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, Japan
| | - Kotaro Takeda
- Faculty of Rehabilitation, School of Healthcare, Fujita Health University, Toyoake, Japan
| | - Isato Fukushi
- Faculty of Health Sciences, Uekusa Gakuen University, Chiba, Japan.,Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
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21
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Chen C, Jiang Z, Fu X, Yu D, Huang H, Tasker JG. Astrocytes Amplify Neuronal Dendritic Volume Transmission Stimulated by Norepinephrine. Cell Rep 2020; 29:4349-4361.e4. [PMID: 31875545 PMCID: PMC7010232 DOI: 10.1016/j.celrep.2019.11.092] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/10/2019] [Accepted: 11/22/2019] [Indexed: 11/03/2022] Open
Abstract
In addition to their support role in neurotransmitter and ion buffering, astrocytes directly regulate neurotransmission at synapses via local bidirectional signaling with neurons. Here, we reveal a form of neuronal-astrocytic signaling that transmits retrograde dendritic signals to distal upstream neurons in order to activate recurrent synaptic circuits. Norepinephrine activates α1 adrenoreceptors in hypothalamic corticotropin-releasing hormone (CRH) neurons to stimulate dendritic release, which triggers an astrocytic calcium response and release of ATP; ATP stimulates action potentials in upstream glutamate and GABA neurons to activate recurrent excitatory and inhibitory synaptic circuits to the CRH neurons. Thus, norepinephrine activates a retrograde signaling mechanism in CRH neurons that engages astrocytes in order to extend dendritic volume transmission to reach distal presynaptic glutamate and GABA neurons, thereby amplifying volume transmission mediated by dendritic release.
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Affiliation(s)
- Chun Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - ZhiYing Jiang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Xin Fu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Diankun Yu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Hai Huang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Jeffrey G Tasker
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA.
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22
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Neuropeptides Modulate Local Astrocytes to Regulate Adult Hippocampal Neural Stem Cells. Neuron 2020; 108:349-366.e6. [PMID: 32877641 DOI: 10.1016/j.neuron.2020.07.039] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 06/12/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
Neural stem cells (NSCs) in the dentate gyrus (DG) reside in a specialized local niche that supports their neurogenic proliferation to produce adult-born neurons throughout life. How local niche cells interact at the circuit level to ensure continuous neurogenesis from NSCs remains unknown. Here we report the role of endogenous neuropeptide cholecystokinin (CCK), released from dentate CCK interneurons, in regulating neurogenic niche cells and NSCs. Specifically, stimulating CCK release supports neurogenic proliferation of NSCs through a dominant astrocyte-mediated glutamatergic signaling cascade. In contrast, reducing dentate CCK induces reactive astrocytes, which correlates with decreased neurogenic proliferation of NSCs and upregulation of genes involved in immune processes. Our findings provide novel circuit-based information on how CCK acts on local astrocytes to regulate the key behavior of adult NSCs.
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23
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Korgaonkar AA, Nguyen S, Li Y, Sekhar D, Subramanian D, Guevarra J, Pang KCH, Santhakumar V. Distinct cellular mediators drive the Janus faces of toll-like receptor 4 regulation of network excitability which impacts working memory performance after brain injury. Brain Behav Immun 2020; 88:381-395. [PMID: 32259563 PMCID: PMC7415537 DOI: 10.1016/j.bbi.2020.03.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 01/15/2023] Open
Abstract
The mechanisms by which the neurophysiological and inflammatory responses to brain injury contribute to memory impairments are not fully understood. Recently, we reported that the innate immune receptor, toll-like receptor 4 (TLR4) enhances AMPA receptor (AMPAR) currents and excitability in the dentate gyrus after fluid percussion brain injury (FPI) while limiting excitability in controls. Here, we examine the cellular mediators underlying TLR4 regulation of dentate excitability and its impact on memory performance. In ex vivo slices, astrocytic and microglial metabolic inhibitors selectively abolished TLR4 antagonist modulation of excitability in controls, but not in rats after FPI, demonstrating that glial signaling contributes to TLR4 regulation of excitability in controls. In glia-depleted neuronal cultures from naïve mice, TLR4 ligands bidirectionally modulated AMPAR charge transfer consistent with neuronal TLR4 regulation of excitability, as observed after brain injury. In vivo TLR4 antagonism reduced early post-injury increases in mediators of MyD88-dependent and independent TLR4 signaling without altering expression in controls. Blocking TNFα, a downstream effector of TLR4, mimicked effects of TLR4 antagonist and occluded TLR4 agonist modulation of excitability in slices from both control and FPI rats. Functionally, transiently blocking TLR4 in vivo improved impairments in working memory observed one week and one month after FPI, while the same treatment impaired memory function in uninjured controls. Together these data identify that distinct cellular signaling mechanisms converge on TNFα to mediate TLR4 modulation of network excitability in the uninjured and injured brain and demonstrate a role for TLR4 in regulation of working memory function.
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Affiliation(s)
- Akshata A. Korgaonkar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103,,Correspondence: Akshata Korgaonkar, PhD, Department of Neurology, Washington University School of Medicine, 660 South Euclid Ave, Campus box 8111, St Louis, MO 63110, Phone (Off): 314.362.2999,
| | - Susan Nguyen
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Ying Li
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
| | - Dipika Sekhar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103,,Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Deepak Subramanian
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103,,Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Jenieve Guevarra
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
| | - Kevin C H Pang
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103,,Neurobehavioral Research Lab, Department of Veteran Affairs Medical Center–New Jersey Health Care System, East Orange, New Jersey
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103,,Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
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24
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Rogers RC, Hasser EM, Hermann GE. Thrombin action on astrocytes in the hindbrain of the rat disrupts glycemic and respiratory control. Am J Physiol Regul Integr Comp Physiol 2020; 318:R1068-R1077. [PMID: 32320636 PMCID: PMC7311679 DOI: 10.1152/ajpregu.00033.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/30/2020] [Accepted: 04/21/2020] [Indexed: 02/06/2023]
Abstract
Severe trauma can produce a postinjury "metabolic self-destruction" characterized by catabolic metabolism and hyperglycemia. The severity of the hyperglycemia is highly correlated with posttrauma morbidity and mortality. Although no mechanism has been posited to connect severe trauma with a loss of autonomic control over metabolism, traumatic injury causes other failures of autonomic function, notably, gastric stasis and ulceration ("Cushing's ulcer"), which has been connected with the generation of thrombin. Our previous studies established that proteinase-activated receptors (PAR1; "thrombin receptors") located on astrocytes in the autonomically critical nucleus of the solitary tract (NST) can modulate gastric control circuit neurons to cause gastric stasis. Hindbrain astrocytes have also been implicated as important detectors of low glucose or glucose utilization. When activated, these astrocytes communicate with hindbrain catecholamine neurons that, in turn, trigger counterregulatory responses (CRR). There may be a convergence between the effects of thrombin to derange hindbrain gastrointestinal control and the hindbrain circuitry that initiates CRR to increase glycemia in reaction to critical hypoglycemia. Our results suggest that thrombin acts within the NST to increase glycemia through an astrocyte-dependent mechanism. Blockade of purinergic gliotransmission pathways interrupted the effect of thrombin to increase glycemia. Our studies also revealed that thrombin, acting in the NST, produced a rapid, dramatic, and potentially lethal suppression of respiratory rhythm that was also a function of purinergic gliotransmission. These results suggest that the critical connection between traumatic injury and a general collapse of autonomic regulation involves thrombin action on astrocytes.
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Affiliation(s)
- Richard C Rogers
- Autonomic Neurosciences Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Eileen M Hasser
- Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Gerlinda E Hermann
- Autonomic Neurosciences Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana
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25
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Dorsal vagal complex and hypothalamic glia differentially respond to leptin and energy balance dysregulation. Transl Psychiatry 2020; 10:90. [PMID: 32152264 PMCID: PMC7062837 DOI: 10.1038/s41398-020-0767-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 02/18/2020] [Accepted: 02/25/2020] [Indexed: 01/16/2023] Open
Abstract
Previous studies identify a role for hypothalamic glia in energy balance regulation; however, a narrow hypothalamic focus provides an incomplete understanding of how glia throughout the brain respond to and regulate energy homeostasis. We examined the responses of glia in the dorsal vagal complex (DVC) to the adipokine leptin and high fat diet-induced obesity. DVC astrocytes functionally express the leptin receptor; in vivo pharmacological studies suggest that DVC astrocytes partly mediate the anorectic effects of leptin in lean but not diet-induced obese rats. Ex vivo calcium imaging indicated that these changes were related to a lower proportion of leptin-responsive cells in the DVC of obese versus lean animals. Finally, we investigated DVC microglia and astroglia responses to leptin and energy balance dysregulation in vivo: obesity decreased DVC astrogliosis, whereas the absence of leptin signaling in Zucker rats was associated with extensive astrogliosis in the DVC and decreased hypothalamic micro- and astrogliosis. These data uncover a novel functional heterogeneity of astrocytes in different brain nuclei of relevance to leptin signaling and energy balance regulation.
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26
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Chan F, Lax NZ, Voss CM, Aldana BI, Whyte S, Jenkins A, Nicholson C, Nichols S, Tilley E, Powell Z, Waagepetersen HS, Davies CH, Turnbull DM, Cunningham MO. The role of astrocytes in seizure generation: insights from a novel in vitro seizure model based on mitochondrial dysfunction. Brain 2019; 142:391-411. [PMID: 30689758 DOI: 10.1093/brain/awy320] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022] Open
Abstract
Approximately one-quarter of patients with mitochondrial disease experience epilepsy. Their epilepsy is often severe and resistant towards conventional antiepileptic drugs. Despite the severity of this epilepsy, there are currently no animal models available to provide a mechanistic understanding of mitochondrial epilepsy. We conducted neuropathological studies on patients with mitochondrial epilepsy and found the involvement of the astrocytic compartment. As a proof of concept, we developed a novel brain slice model of mitochondrial epilepsy by the application of an astrocytic-specific aconitase inhibitor, fluorocitrate, concomitant with mitochondrial respiratory inhibitors, rotenone and potassium cyanide. The model was robust and exhibited both face and predictive validity. We then used the model to assess the role that astrocytes play in seizure generation and demonstrated the involvement of the GABA-glutamate-glutamine cycle. Notably, glutamine appears to be an important intermediary molecule between the neuronal and astrocytic compartment in the regulation of GABAergic inhibitory tone. Finally, we found that a deficiency in glutamine synthetase is an important pathogenic process for seizure generation in both the brain slice model and the human neuropathological study. Our study describes the first model for mitochondrial epilepsy and provides a mechanistic insight into how astrocytes drive seizure generation in mitochondrial epilepsy.
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Affiliation(s)
- Felix Chan
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK.,Wellcome Centre for Mitochondrial Research, Newcastle University, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Nichola Z Lax
- Wellcome Centre for Mitochondrial Research, Newcastle University, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Caroline Marie Voss
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Shuna Whyte
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Alistair Jenkins
- Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Claire Nicholson
- Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Sophie Nichols
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Elizabeth Tilley
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Zoe Powell
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Ceri H Davies
- Neural Pathways DPU, GSK, 11 Biopolis Way, Singapore
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Newcastle University, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, UK
| | - Mark O Cunningham
- Institute of Neuroscience, Newcastle University, The Medical School, Framlington Place, Newcastle upon Tyne, UK.,Discipline of Physiology, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
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27
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Singh MB, White JA, McKimm EJ, Milosevic MM, Antic SD. Mechanisms of Spontaneous Electrical Activity in the Developing Cerebral Cortex-Mouse Subplate Zone. Cereb Cortex 2019; 29:3363-3379. [PMID: 30169554 PMCID: PMC7963116 DOI: 10.1093/cercor/bhy205] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/28/2018] [Accepted: 08/05/2018] [Indexed: 12/15/2022] Open
Abstract
Subplate (SP) neurons exhibit spontaneous plateau depolarizations mediated by connexin hemichannels. Postnatal (P1-P6) mice show identical voltage pattern and drug-sensitivity as observed in slices from human fetal cortex; indicating that the mouse is a useful model for studying the cellular physiology of the developing neocortex. In mouse SP neurons, spontaneous plateau depolarizations were insensitive to blockers of: synaptic transmission (glutamatergic, GABAergic, or glycinergic), pannexins (probenecid), or calcium channels (mibefradil, verapamil, diltiazem); while highly sensitive to blockers of gap junctions (octanol), hemichannels (La3+, lindane, Gd3+), or glial metabolism (DLFC). Application of La3+ (100 μM) does not exert its effect on electrical activity by blocking calcium channels. Intracellular application of Gd3+ determined that Gd3+-sensitive pores (putative connexin hemichannels) reside on the membrane of SP neurons. Immunostaining of cortical sections (P1-P6) detected connexins 26, and 45 in neurons, but not connexins 32 and 36. Vimentin-positive glial cells were detected in the SP zone suggesting a potential physiological interaction between SP neurons and radial glia. SP spontaneous activity was reduced by blocking glial metabolism with DFLC or by blocking purinergic receptors by PPADS. Connexin hemichannels and ATP release from vimentin-positive glial cells may underlie spontaneous plateau depolarizations in the developing mammalian cortex.
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Affiliation(s)
- Mandakini B Singh
- Institute for Systems Genomics, Stem Cell Institute, Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Jesse A White
- Institute for Systems Genomics, Stem Cell Institute, Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Eric J McKimm
- Institute for Systems Genomics, Stem Cell Institute, Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Milena M Milosevic
- Institute for Systems Genomics, Stem Cell Institute, Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Srdjan D Antic
- Institute for Systems Genomics, Stem Cell Institute, Department of Neuroscience, UConn Health, Farmington, CT, USA
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28
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Inhibition of Reactive Astrocytes with Fluorocitrate Ameliorates Learning and Memory Impairment Through Upregulating CRTC1 and Synaptophysin in Ischemic Stroke Rats. Cell Mol Neurobiol 2019; 39:1151-1163. [PMID: 31270712 DOI: 10.1007/s10571-019-00709-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/19/2019] [Indexed: 12/12/2022]
Abstract
Ischemic stroke often causes motor and cognitive deficits. Deregulated glia gap junction communication, which is reflected by increased protein levels of glial fibrillary acidic protein (GFAP) and connexin 43 (Cx43), has been observed in ischemic hippocampus and has been associated with cognitive impairment in animal stroke models. Here, we tested the hypothesis that reactive astrocytes-mediated loss of synaptophysin (SYP) and CREB-regulated transcription coactivator 1 (CRTC1) contribute to dysfunction in glia gap junction communication and memory impairment after ischemic stroke. Male Sprague-Dawley rats were subjected to a 90-min middle cerebral artery occlusion (MCAO) with 7-day reperfusion. Fluorocitrate (1 nmol), the reversible inhibitor of the astrocytic tricarboxylic acid cycle, was injected into the right lateral ventricle of MCAO rats once every 2 days starting immediately before reperfusion. The Morris water maze was used to assess memory in conjunction with western blotting and immunostaining to detect protein expression and distribution in the hippocampus. Our results showed that ischemic stroke caused significant memory impairment accompanied by increased protein levels of GFAP and Cx43 in hippocampal tissue. In addition, the levels of several key memory-related important proteins including SYP, CRTC1, myelin basic protein and high-mobility group-box-1 were significantly reduced in the hippocampal tissue. Of note, inhibition of reactive astrocytes with fluorocitrate was shown to significantly reverse the above noted changes induced by ischemic stroke. Taken together, our findings demonstrate that inhibiting reactive astrocytes with fluorocitrate immediately before reperfusion may protect against ischemic stroke-induced memory impairment through the upregulation of CRTC1 and SYP.
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29
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Chemokines CCL2 and CCL7, but not CCL12, play a significant role in the development of pain-related behavior and opioid-induced analgesia. Cytokine 2019; 119:202-213. [DOI: 10.1016/j.cyto.2019.03.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 03/04/2019] [Accepted: 03/11/2019] [Indexed: 12/28/2022]
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30
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Joo K, Cho KH, Youn SH, Jang HJ, Rhie DJ. Layer-specific involvement of endocannabinoid signaling in muscarinic-induced long-term depression in layer 2/3 pyramidal neurons of rat visual cortex. Brain Res 2019; 1712:124-131. [DOI: 10.1016/j.brainres.2019.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/23/2019] [Accepted: 02/08/2019] [Indexed: 02/01/2023]
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31
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Belozor OS, Yakovleva DA, Potapenko IV, Shuvaev AN, Smolnikova MV, Vasilev A, Pozhilenkova EA, Shuvaev AN. Extracellular S100β Disrupts Bergman Glia Morphology and Synaptic Transmission in Cerebellar Purkinje Cells. Brain Sci 2019; 9:brainsci9040080. [PMID: 31013844 PMCID: PMC6523464 DOI: 10.3390/brainsci9040080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 12/24/2022] Open
Abstract
Astrogliosis is a pathological process that affects the density, morphology, and function of astrocytes. It is a common feature of brain trauma, autoimmune diseases, and neurodegeneration including spinocerebellar ataxia type 1 (SCA1), a poorly understood neurodegenerative disease. S100β is a Ca2+ binding protein. In SCA1, excessive excretion of S100β by reactive astrocytes and its uptake by Purkinje cells has been demonstrated previously. Under pathological conditions, excessive extracellular concentration of S100β stimulates the production of proinflammatory cytokines and induces apoptosis. We modeled astrogliosis by S100β injections into cerebellar cortex in mice. Injections of S100β led to significant changes in Bergmann glia (BG) cortical organization and affected their processes. S100β also changed morphology of the Purkinje cells (PCs), causing a significant reduction in the dendritic length. Moreover, the short-term synaptic plasticity and depolarization-induced suppression of synaptic transmission were disrupted after S100β injections. We speculate that these effects are the result of Ca2+-chelating properties of S100β protein. In summary, exogenous S100β induced astrogliosis in cerebellum could lead to neuronal dysfunction, which resembles a natural neurodegenerative process. We suggest that astrocytes play an essential role in SCA1 pathology, and that astrocytic S100β is an important contributor to this process.
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Affiliation(s)
- Olga S Belozor
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Department of Biological Chemistry, Medical Pharmaceutical and Toxicological Chemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
| | - Dariya A Yakovleva
- Siberian Federal University, Svobodny pr., 79, 660041 Krasnoyarsk, Russia.
| | - Ilya V Potapenko
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
| | - Andrey N Shuvaev
- Siberian Federal University, Svobodny pr., 79, 660041 Krasnoyarsk, Russia.
| | - Marina V Smolnikova
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
- Federal Research Center "Krasnoyarsk Science Center" of the Siberian Branch of the Russian Academy of Sciences, Scientific Research Institute of Medical Problems of the North, Partizan Zheleznyak st., 3G, 660022 Krasnoyarsk, Russia.
| | - Alex Vasilev
- Institute of Living Systems, Immanuel Kant Baltic Federal University, Universitetskaya st., 2, 236041 Kaliningrad, Russia.
| | - Elena A Pozhilenkova
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Department of Biological Chemistry, Medical Pharmaceutical and Toxicological Chemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
| | - Anton N Shuvaev
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry, Partizan Zheleznyak st. 1, 660022 Krasnoyarsk, Russia.
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Masuoka T, Ikeda R, Konishi S. Persistent activation of histamine H 1 receptors in the hippocampal CA1 region enhances NMDA receptor-mediated synaptic excitation and long-term potentiation in astrocyte- and D-serine-dependent manner. Neuropharmacology 2019; 151:64-73. [PMID: 30943384 DOI: 10.1016/j.neuropharm.2019.03.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 03/01/2019] [Accepted: 03/29/2019] [Indexed: 01/05/2023]
Abstract
Behavioral studies using pharmacological tools have implicated histamine H1 receptors in cognitive function via their interactions with N-methyl-D-aspartate receptors (NMDARs) in the hippocampus. However, little is known about the neurophysiological mechanism that underlies the interaction between H1 receptors and NMDARs. To explore how H1 receptor activation affects hippocampal excitatory neurotransmission and synaptic plasticity, this study aimed to examine the effect of H1 receptor ligands on both NMDAR-mediated synaptic currents and long-term potentiation (LTP) at synapses between Schaffer collaterals and CA1 pyramidal neurons using acute mouse hippocampal slices. We found that the H1 receptor antagonist/inverse agonists, pyrilamine (0.1 μM) and cetirizine (10 μM), decreased the NMDAR-mediated component of stimulation-induced excitatory postsynaptic currents (EPSCs) recorded from CA1 pyramidal neurons without affecting the AMPA receptor-mediated component of EPSCs and its paired pulse ratio. Pretreatment of slices with either the glial metabolism inhibitor, fluoroacetate (5 mM), or D-serine (100 μM) diminished the pyrilamine- or cetirizine-induced attenuation of the NMDAR-mediated EPSCs. Furthermore, the LTP of field excitatory postsynaptic potentials induced following high frequency stimulation of Schaffer collaterals was attenuated with application of pyrilamine or cetirizine. Pretreatment with D-serine again attenuated the pyrilamine-induced suppression of LTP. Our data suggest that H1 receptors in the CA1 can undergo persistent activation induced by their constitutive receptor activity and/or tonic release of endogenous histamine, resulting in facilitation of the NMDAR activity in a manner dependent of astrocytes and the release of D-serine. This led to the enhancement of NMDA-component EPSC and LTP at the Schaffer collateral-CA1 pyramidal neuron synapses.
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Affiliation(s)
- Takayoshi Masuoka
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, 769-2193, Japan; Department of Pharmacology, School of Medicine, Kanazawa Medical University, Ishikawa, 920-0293, Japan.
| | - Ryo Ikeda
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, 769-2193, Japan
| | - Shiro Konishi
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, 769-2193, Japan
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Inhibition of activated astrocyte ameliorates lipopolysaccharide- induced depressive-like behaviors. J Affect Disord 2019; 242:52-59. [PMID: 30172225 DOI: 10.1016/j.jad.2018.08.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/05/2018] [Accepted: 08/07/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Numerous studies indicate that inflammation plays important roles in the development of depression. Astrocytes are crucial regulators of immune response in the central nervous system, and strongly activated by pro-inflammatory cytokines. We hypothesized that inhibition of activated astrocytes contributed to ameliorate depressive-like symptoms. METHODS This study evaluated the antidepressant-like effect of inhibition of activated astrocytes, by a well-established astrocyte inactivator fluorocitrate (FC), on a lipopolysaccharide (LPS)-induced model of depression. Forced swim test (FST), tail suspension test (TST) and sucrose preference test were used to assess depressive-like behaviors. The expression of fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and neuroinflammation were determined in the hippocampus and cortex. RESULTS The results demonstrated that LPS increased immobility time in the TST and FST, reduced sucrose preference as well. LPS also enhanced the expression of IL-1β, TNF-α, iNOS and GFAP, accompanying with decreased expression of BDNF in the hippocampus and cortex. Inhibition of activated astrocytes by FC significantly prevented LPS- induced alteration in the FST, TST and sucrose preference test. Moreover, in the hippocampus and cortex, inhibition of activated astrocytes by FC significantly attenuated increases of neuroinflammation and GFAP whereas reversed decrease of BDNF in LPS- challenged depression. CONCLUSIONS Taken together, the results suggest that inhibition of activated astrocytes ameliorates LPS-induced depressive-like behavior, providing the first evidence that inhibition of activated astrocytes might represent a novel therapeutic target for depression.
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Cholecystokinin Switches the Plasticity of GABA Synapses in the Dorsomedial Hypothalamus via Astrocytic ATP Release. J Neurosci 2018; 38:8515-8525. [PMID: 30108130 DOI: 10.1523/jneurosci.0569-18.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 07/05/2018] [Accepted: 08/08/2018] [Indexed: 12/31/2022] Open
Abstract
Whether synapses in appetite-regulatory brain regions undergo long-term changes in strength in response to satiety peptides is poorly understood. Here we show that following bursts of afferent activity, the neuromodulator and satiety peptide cholecystokinin (CCK) shifts the plasticity of GABA synapses in the dorsomedial nucleus of the hypothalamus of male Sprague Dawley rats from long-term depression to long-term potentiation (LTP). This LTP requires the activation of both type 2 CCK receptors and group 5 metabotropic glutamate receptors, resulting in a rise in astrocytic intracellular calcium and subsequent ATP release. ATP then acts on presynaptic P2X receptors to trigger a prolonged increase in GABA release. Our observations demonstrate a novel form of CCK-mediated plasticity that requires astrocytic ATP release, and could serve as a mechanism for appetite regulation.SIGNIFICANCE STATEMENT Satiety peptides, like cholecystokinin, play an important role in the central regulation of appetite, but their effect on synaptic plasticity is not well understood. The current data provide novel evidence that cholecystokinin shifts the plasticity from long-term depression to long-term potentiation at GABA synapses in the rat dorsomedial nucleus of the hypothalamus. We also demonstrate that this plasticity requires the concerted action of cholecystokinin and glutamate on astrocytes, triggering the release of the gliotransmitter ATP, which subsequently increases GABA release from neighboring inhibitory terminals. This research reveals a novel neuropeptide-induced switch in the direction of synaptic plasticity that requires astrocytes, and could represent a new mechanism by which cholecystokinin regulates appetite.
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Delp J, Gutbier S, Cerff M, Zasada C, Niedenführ S, Zhao L, Smirnova L, Hartung T, Borlinghaus H, Schreiber F, Bergemann J, Gätgens J, Beyss M, Azzouzi S, Waldmann T, Kempa S, Nöh K, Leist M. Stage-specific metabolic features of differentiating neurons: Implications for toxicant sensitivity. Toxicol Appl Pharmacol 2017; 354:64-80. [PMID: 29278688 DOI: 10.1016/j.taap.2017.12.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 12/19/2017] [Accepted: 12/22/2017] [Indexed: 01/08/2023]
Abstract
Developmental neurotoxicity (DNT) may be induced when chemicals disturb a key neurodevelopmental process, and many tests focus on this type of toxicity. Alternatively, DNT may occur when chemicals are cytotoxic only during a specific neurodevelopmental stage. The toxicant sensitivity is affected by the expression of toxicant targets and by resilience factors. Although cellular metabolism plays an important role, little is known how it changes during human neurogenesis, and how potential alterations affect toxicant sensitivity of mature vs. immature neurons. We used immature (d0) and mature (d6) LUHMES cells (dopaminergic human neurons) to provide initial answers to these questions. Transcriptome profiling and characterization of energy metabolism suggested a switch from predominantly glycolytic energy generation to a more pronounced contribution of the tricarboxylic acid cycle (TCA) during neuronal maturation. Therefore, we used pulsed stable isotope-resolved metabolomics (pSIRM) to determine intracellular metabolite pool sizes (concentrations), and isotopically non-stationary 13C-metabolic flux analysis (INST 13C-MFA) to calculate metabolic fluxes. We found that d0 cells mainly use glutamine to fuel the TCA. Furthermore, they rely on extracellular pyruvate to allow continuous growth. This metabolic situation does not allow for mitochondrial or glycolytic spare capacity, i.e. the ability to adapt energy generation to altered needs. Accordingly, neuronal precursor cells displayed a higher sensitivity to several mitochondrial toxicants than mature neurons differentiated from them. In summary, this study shows that precursor cells lose their glutamine dependency during differentiation while they gain flexibility of energy generation and thereby increase their resistance to low concentrations of mitochondrial toxicants.
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Affiliation(s)
- Johannes Delp
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457 Konstanz, Germany
| | - Simon Gutbier
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457 Konstanz, Germany
| | - Martin Cerff
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Christin Zasada
- Max-Delbrück-Center of Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Sebastian Niedenführ
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Liang Zhao
- Johns Hopkins University, Bloomberg School of Public Health, Center for Alternatives to Animal Testing (CAAT), Baltimore, MD, USA
| | - Lena Smirnova
- Johns Hopkins University, Bloomberg School of Public Health, Center for Alternatives to Animal Testing (CAAT), Baltimore, MD, USA
| | - Thomas Hartung
- Johns Hopkins University, Bloomberg School of Public Health, Center for Alternatives to Animal Testing (CAAT), Baltimore, MD, USA
| | - Hanna Borlinghaus
- Department of Computer and Information Science, University of Konstanz, Konstanz, Germany
| | - Falk Schreiber
- Department of Computer and Information Science, University of Konstanz, Konstanz, Germany; Faculty of Information Technology, Monash University, Melbourne, Australia
| | - Jörg Bergemann
- Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, Sigmaringen, Germany
| | - Jochem Gätgens
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Martin Beyss
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Salah Azzouzi
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Tanja Waldmann
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457 Konstanz, Germany
| | - Stefan Kempa
- Max-Delbrück-Center of Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Katharina Nöh
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Marcel Leist
- In Vitro Toxicology and Biomedicine, Dept Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, 78457 Konstanz, Germany; CAAT-Europe, University of Konstanz, Konstanz 78457, Germany.
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Silva-Cruz A, Carlström M, Ribeiro JA, Sebastião AM. Dual Influence of Endocannabinoids on Long-Term Potentiation of Synaptic Transmission. Front Pharmacol 2017; 8:921. [PMID: 29311928 PMCID: PMC5742107 DOI: 10.3389/fphar.2017.00921] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/05/2017] [Indexed: 12/16/2022] Open
Abstract
Cannabinoid receptor 1 (CB1R) is widely distributed in the central nervous system, in excitatory and inhibitory neurons, and in astrocytes. CB1R agonists impair cognition and prevent long-term potentiation (LTP) of synaptic transmission, but the influence of endogenously formed cannabinoids (eCBs) on hippocampal LTP remains ambiguous. Based on the knowledge that eCBs are released upon high frequency neuronal firing, we hypothesized that the influence of eCBs upon LTP could change according to the paradigm of LTP induction. We thus tested the influence of eCBs on hippocampal LTP using two θ-burst protocols that induce either a weak or a strong LTP. LTP induced by a weak-θ-burst protocol is facilitated while preventing the endogenous activation of CB1Rs. In contrast, the same procedures lead to inhibition of LTP induced by the strong-θ-burst protocol, suggestive of a facilitatory action of eCBs upon strong LTP. Accordingly, an inhibitor of the metabolism of the predominant eCB in the hippocampus, 2-arachidonoyl-glycerol (2-AG), facilitates strong LTP. The facilitatory action of endogenous CB1R activation does not require the activity of inhibitory A1 adenosine receptors, is not affected by inhibition of astrocytic metabolism, but involves inhibitory GABAergic transmission. The continuous activation of CB1Rs via exogenous cannabinoids, or by drugs known to prevent metabolism of the non-prevalent hippocampal eCB, anandamide, inhibited LTP. We conclude that endogenous activation of CB1Rs by physiologically formed eCBs exerts a fine-tune homeostatic control of LTP in the hippocampus, acting as a high-pass filter, therefore likely reducing the signal-to-noise ratio of synaptic strengthening.
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Affiliation(s)
- Armando Silva-Cruz
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Mattias Carlström
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Joaquim A. Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ana M. Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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Beltrán-Castillo S, Olivares MJ, Contreras RA, Zúñiga G, Llona I, von Bernhardi R, Eugenín JL. D-serine released by astrocytes in brainstem regulates breathing response to CO 2 levels. Nat Commun 2017; 8:838. [PMID: 29018191 PMCID: PMC5635109 DOI: 10.1038/s41467-017-00960-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 08/09/2017] [Indexed: 11/17/2022] Open
Abstract
Central chemoreception is essential for adjusting breathing to physiological demands, and for maintaining CO2 and pH homeostasis in the brain. CO2-induced ATP release from brainstem astrocytes stimulates breathing. NMDA receptor (NMDAR) antagonism reduces the CO2-induced hyperventilation by unknown mechanisms. Here we show that astrocytes in the mouse caudal medullary brainstem can synthesize, store, and release d-serine, an agonist for the glycine-binding site of the NMDAR, in response to elevated CO2 levels. We show that systemic and raphe nucleus d-serine administration to awake, unrestrained mice increases the respiratory frequency. Application of d-serine to brainstem slices also increases respiratory frequency, which was prevented by NMDAR blockade. Inhibition of d-serine synthesis, enzymatic degradation of d-serine, or the sodium fluoroacetate-induced impairment of astrocyte functions decrease the basal respiratory frequency and the CO2-induced respiratory response in vivo and in vitro. Our findings suggest that astrocytic release of d-serine may account for the glutamatergic contribution to central chemoreception. Astrocytes are involved in chemoreception in brainstem areas that regulate breathing rhythm, and astrocytes are known to release d-serine. Here the authors show that astrocyte release of d-serine contributes to CO2 sensing and breathing in brainstem slices, and in vivo in awake unrestrained mice.
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Affiliation(s)
- S Beltrán-Castillo
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile
| | - M J Olivares
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile
| | - R A Contreras
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile
| | - G Zúñiga
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile
| | - I Llona
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile
| | - R von Bernhardi
- Departamento de Neurología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, 8330024, Chile.
| | - J L Eugenín
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Santiago, 9170022, Chile.
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Piacentini R, Puma DDL, Mainardi M, Lazzarino G, Tavazzi B, Arancio O, Grassi C. Reduced gliotransmitter release from astrocytes mediates tau-induced synaptic dysfunction in cultured hippocampal neurons. Glia 2017; 65:1302-1316. [PMID: 28519902 PMCID: PMC5520670 DOI: 10.1002/glia.23163] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/13/2017] [Accepted: 04/18/2017] [Indexed: 01/19/2023]
Abstract
Tau is a microtubule-associated protein exerting several physiological functions in neurons. In Alzheimer's disease (AD) misfolded tau accumulates intraneuronally and leads to axonal degeneration. However, tau has also been found in the extracellular medium. Recent studies indicated that extracellular tau uploaded from neurons causes synaptic dysfunction and contributes to tau pathology propagation. Here we report novel evidence that extracellular tau oligomers are abundantly and rapidly accumulated in astrocytes where they disrupt intracellular Ca2+ signaling and Ca2+ -dependent release of gliotransmitters, especially ATP. Consequently, synaptic vesicle release, the expression of pre- and postsynaptic proteins, and mEPSC frequency and amplitude were reduced in neighboring neurons. Notably, we found that tau uploading from astrocytes required the amyloid precursor protein, APP. Collectively, our findings suggests that astrocytes play a critical role in the synaptotoxic effects of tau via reduced gliotransmitter availability, and that astrocytes are major determinants of tau pathology in AD.
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Affiliation(s)
- Roberto Piacentini
- Institute of Human Physiology, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
| | - Domenica Donatella Li Puma
- Institute of Human Physiology, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
| | - Marco Mainardi
- Institute of Human Physiology, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
| | - Giacomo Lazzarino
- Institute of Biochemistry and Clinical Biochemistry, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
| | - Barbara Tavazzi
- Institute of Biochemistry and Clinical Biochemistry, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
| | - Ottavio Arancio
- Department of Pathology and Cell Biology and Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, 630 W 168th St., NY 10032 USA
| | - Claudio Grassi
- Institute of Human Physiology, Medical School, Università Cattolica, Largo F. Vito 1, 00168, Rome, Italy
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Nonose Y, Gewehr PE, Almeida RF, da Silva JS, Bellaver B, Martins LAM, Zimmer ER, Greggio S, Venturin GT, Da Costa JC, Quincozes-Santos A, Pellerin L, de Souza DO, de Assis AM. Cortical Bilateral Adaptations in Rats Submitted to Focal Cerebral Ischemia: Emphasis on Glial Metabolism. Mol Neurobiol 2017; 55:2025-2041. [PMID: 28271402 DOI: 10.1007/s12035-017-0458-x] [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: 12/11/2016] [Accepted: 02/13/2017] [Indexed: 11/30/2022]
Abstract
This study was performed to evaluate the bilateral effects of focal permanent ischemia (FPI) on glial metabolism in the cerebral cortex. Two and 9 days after FPI induction, we analyze [18F]FDG metabolism by micro-PET, astrocyte morphology and reactivity by immunohistochemistry, cytokines and trophic factors by ELISA, glutamate transporters by RT-PCR, monocarboxylate transporters (MCTs) by western blot, and substrate uptake and oxidation by ex vivo slices model. The FPI was induced surgically by thermocoagulation of the blood in the pial vessels of the motor and sensorimotor cortices in adult (90 days old) male Wistar rats. Neurochemical analyses were performed separately on both ipsilateral and contralateral cortical hemispheres. In both cortical hemispheres, we observed an increase in tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and glutamate transporter 1 (GLT-1) mRNA levels; lactate oxidation; and glutamate uptake and a decrease in brain-derived neurotrophic factor (BDNF) after 2 days of FPI. Nine days after FPI, we observed an increase in TNF-α levels and a decrease in BDNF, GLT-1, and glutamate aspartate transporter (GLAST) mRNA levels in both hemispheres. Additionally, most of the unilateral alterations were found only in the ipsilateral hemisphere and persisted until 9 days post-FPI. They include diminished in vivo glucose uptake and GLAST expression, followed by increased glial fibrillary acidic protein (GFAP) gray values, astrocyte reactivity, and glutamate oxidation. Astrocytes presented signs of long-lasting reactivity, showing a radial morphology. In the intact hemisphere, there was a decrease in MCT2 levels, which did not persist. Our study shows the bilateralism of glial modifications following FPI, highlighting the role of energy metabolism adaptations on brain recovery post-ischemia.
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Affiliation(s)
- Yasmine Nonose
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Pedro E Gewehr
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Roberto F Almeida
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Jussemara S da Silva
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Bruna Bellaver
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Leo A M Martins
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - Eduardo R Zimmer
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.,Brain Institute of Rio Grande do Sul, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, 90619-900, Brazil
| | - Samuel Greggio
- Brain Institute of Rio Grande do Sul, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, 90619-900, Brazil
| | - Gianina T Venturin
- Brain Institute of Rio Grande do Sul, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, 90619-900, Brazil
| | - Jaderson C Da Costa
- Brain Institute of Rio Grande do Sul, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, 90619-900, Brazil
| | - André Quincozes-Santos
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, 90035-003, Brazil
| | - Luc Pellerin
- Department of Physiology, University of Lausanne, 1005, Lausanne, Switzerland
| | - Diogo O de Souza
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, 90035-003, Brazil
| | - Adriano M de Assis
- Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.
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Bémeur C, Cudalbu C, Dam G, Thrane AS, Cooper AJL, Rose CF. Brain edema: a valid endpoint for measuring hepatic encephalopathy? Metab Brain Dis 2016; 31:1249-1258. [PMID: 27272740 DOI: 10.1007/s11011-016-9843-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 05/19/2016] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) is a major complication of liver failure/disease which frequently develops during the progression of end-stage liver disease. This metabolic neuropsychiatric syndrome involves a spectrum of symptoms, including cognition impairment, attention deficits and motor dysfunction which eventually can progress to coma and death. Pathologically, HE is characterized by swelling of the astrocytes which consequently leads to brain edema, a common feature found in patients with acute liver failure (ALF) as well as in cirrhotic patients suffering from HE. The pathogenic factors involved in the onset of astrocyte swelling and brain edema in HE are unresolved. However, the role of astrocyte swelling/brain edema in the development of HE remains ambiguous and therefore measuring brain edema as an endpoint to evaluate HE is questioned. The following review will determine the effect of astrocyte swelling and brain edema on neurological function, discuss the various possible techniques to measure brain edema and lastly to propose a number of neurobehavioral tests to evaluate HE.
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Affiliation(s)
- Chantal Bémeur
- Département de nutrition, Université de Montréal, Montréal, Québec, Canada
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada
| | - Cristina Cudalbu
- Centre d'Imagerie Biomédicale (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Gitte Dam
- Department of Medicine V (Hepatology and Gastroenterology), Aarhus, Denmark
| | - Alexander S Thrane
- Department of Ophthalmology, Haukeland University Hospital, 5012, Bergen, Norway
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York, 14642, USA
| | - Arthur J L Cooper
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, 10595, USA
| | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada.
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McClain JL, Gulbransen BD. The acute inhibition of enteric glial metabolism with fluoroacetate alters calcium signaling, hemichannel function, and the expression of key proteins. J Neurophysiol 2016; 117:365-375. [PMID: 27784805 DOI: 10.1152/jn.00507.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/25/2016] [Indexed: 11/22/2022] Open
Abstract
Glia play key roles in the regulation of neurotransmission in the nervous system. Fluoroacetate (FA) is a metabolic poison widely used to study glial functions by disrupting the tricarboxylic acid cycle enzyme aconitase. Despite the widespread use of FA, the effects of FA on essential glial functions such as calcium (Ca2+) signaling and hemichannel function remain unknown. Therefore, our goal was to assess specifically the impact of FA on essential glial cell functions that are involved with neurotransmission in the enteric nervous system. To this end, we generated a new optogenetic mouse model to study specifically the effects of FA on enteric glial Ca2+ signaling by crossing PC::G5-tdTomato mice with Sox10::creERT2 mice. FA did not change the peak glial Ca2+ response when averaged across all glia within a ganglion. However, FA decreased the percent of responding glia by 30% (P < 0.05) and increased the peak Ca2+ response of the glial cells that still exhibited a response by 26% (P < 0.01). Disruption of Ca2+ signaling with FA impaired the activity-dependent uptake of ethidium bromide through connexin-43 (Cx43) hemichannels (P < 0.05) but did not affect baseline Cx43-dependent dye uptake. FA did not cause overt glial or neurodegeneration, but glial cells significantly increased glial fibrillary acid protein by 56% (P < 0.05) following treatment with FA. Together, these data show that the acute impairment of glial metabolism with FA causes key changes in glial functions associated with their roles in neurotransmission and phenotypic changes indicative of reactive gliosis. NEW & NOTEWORTHY Our study shows that the acute impairment of enteric glial metabolism with fluoroacetate (FA) alters specific glial functions that are associated with the modification of neurotransmission in the gut. These include subtle changes to glial agonist-evoked calcium signaling, the subsequent disruption of connexin-43 hemichannels, and changes in protein expression that are consistent with a transition to reactive glia. These changes in glial function offer a mechanistic explanation for the effects of FA on peripheral neuronal networks.
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Affiliation(s)
- Jonathon L McClain
- Department of Physiology, Michigan State University, East Lansing, Michigan; and
| | - Brian D Gulbransen
- Department of Physiology, Michigan State University, East Lansing, Michigan; and .,Neuroscience Program, Michigan State University, East Lansing, Michigan
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Collicchio-Zuanaze RC, Sakate M, Schwartz DS, Trezza E, Crocci AJ. Calcium gluconate and sodium succinate for therapy of sodium fluoroacetate experimental intoxication in cats: clinical and electrocardiographic evaluation. Hum Exp Toxicol 2016; 25:175-82. [PMID: 16696292 DOI: 10.1191/0960327106ht609oa] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sodium fluoroacetate (SFAC) or Compound 1080 is a potent rodenticide, largely used after 1946 for rodent and home pest control. The toxic effects of SFAC are caused by fluorocitrate action, a toxic metabolite, which has a competitive action with aconitase enzyme, leading to citrate accumulation and resulting in interference in energy production by Krebs cycle blockade. In the present study, domestic cats were intoxicated with oral doses of fluoroacetate (0.45 mg/kg). The intoxicated animals presented emesis, diarrhea with abdominal pain posture and an abdominal palpation, tachypnea, bilateral midriasis, hypothermia, hyperexcitability and convulsions. Blood gas analysis indicated decreased pH and bicarbonate levels. Serum ionized calcium was also decreased. ECG showed non–specific changes in ventricular repolarization and ventricular arrhythmias. The survival rate was 75% in the treated group with calcium gluconate and sodium succinate and 37.5% in the nontreated group.
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Affiliation(s)
- R C Collicchio-Zuanaze
- Department of Veterinary Clinic, Faculty of Veterinary Medicine and Animal Science of the São Paulo State University - UNESP, Botucatu, Brazil.
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Rogers RC, Ritter S, Hermann GE. Hindbrain cytoglucopenia-induced increases in systemic blood glucose levels by 2-deoxyglucose depend on intact astrocytes and adenosine release. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1102-8. [PMID: 27101298 PMCID: PMC4935490 DOI: 10.1152/ajpregu.00493.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/07/2016] [Indexed: 01/16/2023]
Abstract
The hindbrain contains critical neurocircuitry responsible for generating defensive physiological responses to hypoglycemia. This counter-regulatory response (CRR) is evoked by local hindbrain cytoglucopenia that causes an autonomically mediated increase in blood glucose, feeding behavior, and accelerated digestion; that is, actions that restore glucose homeostasis. Recent reports suggest that CRR may be initially triggered by astrocytes in the hindbrain. The present studies in thiobutabarbital-anesthetized rats show that exposure of the fourth ventricle (4V) to 2-deoxyglucose (2DG; 15 μmol) produced a 35% increase in circulating glucose relative to baseline levels. While the 4V application of the astrocytic signal blocker, fluorocitrate (FC; 5 nmol), alone, had no effect on blood glucose levels, 2DG-induced increases in glucose were blocked by 4V FC. The 4V effect of 2DG to increase glycemia was also blocked by the pretreatment with caffeine (nonselective adenosine antagonist) or a potent adenosine A1 antagonist (8-cyclopentyl-1,3-dipropylxanthine; DPCPX) but not the NMDA antagonist (MK-801). These results suggest that CNS detection of glucopenia is mediated by astrocytes and that astrocytic release of adenosine that occurs after hypoglycemia may cause the activation of downstream neural circuits that drive CRR.
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Affiliation(s)
- Richard C. Rogers
- 1Autonomic Neurosciences Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana; and
| | - Sue Ritter
- 2Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Gerlinda E. Hermann
- 1Autonomic Neurosciences Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana; and
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Peña-Ortega F, Rivera-Angulo AJ, Lorea-Hernández JJ. Pharmacological Tools to Study the Role of Astrocytes in Neural Network Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:47-66. [DOI: 10.1007/978-3-319-40764-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Role of Astrocytes in Central Respiratory Chemoreception. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:109-145. [PMID: 27714687 DOI: 10.1007/978-3-319-40764-7_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Astrocytes perform various homeostatic functions in the nervous system beyond that of a supportive or metabolic role for neurons. A growing body of evidence indicates that astrocytes are crucial for central respiratory chemoreception. This review presents a classical overview of respiratory central chemoreception and the new evidence for astrocytes as brainstem sensors in the respiratory response to hypercapnia. We review properties of astrocytes for chemosensory function and for modulation of the respiratory network. We propose that astrocytes not only mediate between CO2/H+ levels and motor responses, but they also allow for two emergent functions: (1) Amplifying the responses of intrinsic chemosensitive neurons through feedforward signaling via gliotransmitters and; (2) Recruiting non-intrinsically chemosensitive cells thanks to volume spreading of signals (calcium waves and gliotransmitters) to regions distant from the CO2/H+ sensitive domains. Thus, astrocytes may both increase the intensity of the neuron responses at the chemosensitive sites and recruit of a greater number of respiratory neurons to participate in the response to hypercapnia.
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Loss of Local Astrocyte Support Disrupts Action Potential Propagation and Glutamate Release Synchrony from Unmyelinated Hippocampal Axon Terminals In Vitro. J Neurosci 2015; 35:11105-17. [PMID: 26245971 DOI: 10.1523/jneurosci.1289-15.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Neuron-astrocyte interactions are critical for proper CNS development and function. Astrocytes secrete factors that are pivotal for synaptic development and function, neuronal metabolism, and neuronal survival. Our understanding of this relationship, however, remains incomplete due to technical hurdles that have prevented the removal of astrocytes from neuronal circuits without changing other important conditions. Here we overcame this obstacle by growing solitary rat hippocampal neurons on microcultures that were comprised of either an astrocyte bed (+astrocyte) or a collagen bed (-astrocyte) within the same culture dish. -Astrocyte autaptic evoked EPSCs, but not IPSCs, displayed an altered temporal profile, which included increased synaptic delay, increased time to peak, and severe glutamate release asynchrony, distinct from previously described quantal asynchrony. Although we observed minimal alteration of the somatically recorded action potential waveform, action potential propagation was altered. We observed a longer latency between somatic initiation and arrival at distal locations, which likely explains asynchronous EPSC peaks, and we observed broadening of the axonal spike, which likely underlies changes to evoked EPSC onset. No apparent changes in axon structure were observed, suggesting altered axonal excitability. In conclusion, we propose that local astrocyte support has an unappreciated role in maintaining glutamate release synchrony by disturbing axonal signal propagation. SIGNIFICANCE STATEMENT Certain glial cell types (oligodendrocytes, Schwann cells) facilitate the propagation of neuronal electrical signals, but a role for astrocytes has not been identified despite many other functions of astrocytes in supporting and modulating neuronal signaling. Under identical global conditions, we cultured neurons with or without local astrocyte support. Without local astrocytes, glutamate transmission was desynchronized by an alteration of the waveform and arrival time of axonal action potentials to synaptic terminals. GABA transmission was not disrupted. The disruption did not involve detectable morphological changes to axons of glutamate neurons. Our work identifies a developmental role for astrocytes in the temporal precision of excitatory signals.
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Pál I, Kardos J, Dobolyi Á, Héja L. Appearance of fast astrocytic component in voltage-sensitive dye imaging of neural activity. Mol Brain 2015; 8:35. [PMID: 26043770 PMCID: PMC4455916 DOI: 10.1186/s13041-015-0127-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 05/24/2015] [Indexed: 12/21/2022] Open
Abstract
Background Voltage-sensitive dye (VSD) imaging and intrinsic optical signals (IOS) are widely used methods for monitoring spatiotemporal neural activity in extensive networks. In spite of that, identification of their major cellular and molecular components has not been concluded so far. Results We addressed these issues by imaging spatiotemporal spreading of IOS and VSD transients initiated by Schaffer collateral stimulation in rat hippocampal slices with temporal resolution comparable to standard field potential recordings using a 464-element photodiode array. By exploring the potential neuronal and astroglial molecular players in VSD and IOS generation, we identified multiple astrocytic mechanisms that significantly contribute to the VSD signal, in addition to the expected neuronal targets. Glutamate clearance through the astroglial glutamate transporter EAAT2 has been shown to be a significant player in VSD generation within a very short (<5 ms) time-scale, indicating that astrocytes do contribute to the development of spatiotemporal VSD transients previously thought to be essentially neuronal. In addition, non-specific anion channels, astroglial K+ clearance through Kir4.1 channel and astroglial Na+/K+ ATPase also contribute to IOS and VSD transients. Conclusion VSD imaging cannot be considered as a spatially extended field potential measurement with predominantly neuronal origin, instead it also reflects a fast communication between neurons and astrocytes.
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Affiliation(s)
- Ildikó Pál
- Group of Functional Pharmacology, Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117, Budapest, Hungary.
| | - Julianna Kardos
- Group of Functional Pharmacology, Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117, Budapest, Hungary.
| | - Árpád Dobolyi
- MTA-ELTE-NAP B Laboratory of Molecular and Systems Neurobiology, H-1117, Budapest, Hungary. .,Department of Anatomy, Human Brain Tissue Bank, Semmelweis University, H-1450, Budapest, Hungary.
| | - László Héja
- Group of Functional Pharmacology, Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117, Budapest, Hungary.
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Han H, Peng Y, Dong Z. d-Serine rescues the deficits of hippocampal long-term potentiation and learning and memory induced by sodium fluoroacetate. Pharmacol Biochem Behav 2015; 133:51-6. [DOI: 10.1016/j.pbb.2015.03.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 03/23/2015] [Accepted: 03/29/2015] [Indexed: 01/12/2023]
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Marx MC, Billups D, Billups B. Maintaining the presynaptic glutamate supply for excitatory neurotransmission. J Neurosci Res 2015; 93:1031-44. [PMID: 25648608 DOI: 10.1002/jnr.23561] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/04/2015] [Accepted: 01/05/2015] [Indexed: 01/09/2023]
Abstract
Glutamate released from synapses during excitatory neurotransmission must be rapidly recycled to maintain neuronal communication. This review evaluates data from physiological experiments at hippocampal CA3 to CA1 synapses and the calyx of Held synapse in the brainstem to analyze quantitatively the rates of release and resupply of glutamate required to sustain neurotransmission. We calculate that, without efficient recycling, the presynaptic glutamate supply will be exhausted within about a minute of normal synaptic activity. We also discuss replenishment of the presynaptic pool by diffusion from the soma, direct uptake of glutamate back into the presynaptic terminal, and uptake of glutamate precursor molecules. Diffusion of glutamate from the soma is calculated to be fast enough to resupply presynaptic glutamate in the hippocampus but not at the calyx of Held. However, because the somatic cytoplasm will also quickly run out of glutamate and synapses can function continually even if the presynaptic axon is severed, mechanisms other than diffusion must be present to resupply glutamate for release. Direct presynaptic uptake of glutamate is not present at the calyx of Held but may play a role in glutamate recycling in the hippocampus. Alternatively, glutamine or tricarboxylic acid cycle intermediates released from glia can serve as a precursor for glutamate in synaptic terminals, and we calculate that the magnitude of presynaptic glutamine uptake is sufficient to supply enough glutamate to sustain neurotransmission. The nature of these mechanisms, their relative abundance, and the co-ordination between them remain areas of intensive investigation.
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Affiliation(s)
- Mari-Carmen Marx
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Daniela Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
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Hindbrain glucoprivation effects on gastric vagal reflex circuits and gastric motility in the rat are suppressed by the astrocyte inhibitor fluorocitrate. J Neurosci 2014; 34:10488-96. [PMID: 25100584 DOI: 10.1523/jneurosci.1406-14.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Fasting and hypoglycemia elicit powerful gastrointestinal contractions. Whereas the relationship between utilizable nutrient and gastric motility is well recognized, the explanation of this phenomenon has remained incomplete. A relatively recent controversial report suggested that astrocytes in the dorsal hindbrain may be the principal detectors of glucoprivic stimuli. Our own studies also show that a subset of astrocytes in the solitary nucleus (NST) is activated by low glucose. It is very likely that information about glucopenia may directly impact gastric control because the hindbrain is also the location of the vago-vagal reflex circuitry regulating gastric motility. Our in vivo single unit neurophysiological recordings in intact rats show fourth ventricular application of 2-deoxyglucose (2-DG) inhibits NST neurons and activates dorsal motor nucleus (DMN) neurons involved in the gastric accommodation reflex. Additionally, as shown in earlier studies, either systemic insulin or central 2-DG causes an increase in gastric motility. These effects on motility were blocked by fourth ventricle pretreatment with the astrocyte inactivator fluorocitrate. Fluorocitrate administered alone has no effect on gastric-NST or -DMN neuron responsiveness, or on gastric motility. These results suggest that glucoprivation-induced increases in gastric motility are dependent on intact hindbrain astrocytes.
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