1
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Tacke C, Bischoff AM, Harb A, Vafadari B, Hülsmann S. Fiber optical imaging of astroglial calcium signaling in the respiratory network in the working heart brainstem preparation. Front Physiol 2023; 14:1237376. [PMID: 37693007 PMCID: PMC10484401 DOI: 10.3389/fphys.2023.1237376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/10/2023] [Indexed: 09/12/2023] Open
Abstract
The neuronal activity in the respiratory network strongly depends on a variety of different neuromodulators. Given the essential role of astrocytes in stabilizing respiratory network activity generated by neurons in the preBötzinger complex (preBötC), our aim was to investigate astrocytic calcium signaling in the working heart brainstem preparation using fiber-optical imaging. By using transgenic mice that express GCaMP6s specifically in astrocytes, we successfully recorded astrocytic calcium signals in response to norepinephrine from individual astrocytes.
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Affiliation(s)
| | | | | | | | - Swen Hülsmann
- Department of Anesthesiology, University Medical Center Göttingen, Göttingen, Germany
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2
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Harhai M, Harsing, Jr LG. An Overview of Glycine Transporter Subtype 1 Inhibitors Under Preclinical and Clinical Evaluation for the Treatment of Alcohol Abuse. CURRENT PSYCHIATRY RESEARCH AND REVIEWS 2022. [DOI: 10.2174/2666082218666220126111415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract:
Being a historical issue that withstands multiple societal control measures, alcohol abuse remains a major healthcare problem. Despite worldwide efforts to limit consumption and educate people about its effects, consumption rates remain unchanged. Alcohol abuse arises from chronic alcohol exposure-caused permanent synaptic plasticity changes in the brain. These manifest in life-threatening withdrawal symptoms and drive relapse even after detoxification and treatment. Since ethanol has multiple targets in the human brain, it warrants a multiapproach therapy; here we introduce the potential therapeutic effects of glycine transporter subtype 1 inhibitors. We have listed the various glycine transporter 1 inhibitors used in studies of alcoholism and how they influenced glycine release from rat hippocampus was demonstrated in a preliminary study. Glycine transporters modulate both glutamatergic and glycinergic pathways: (i) glutamatergic neurotransmission plays an important role in the development of chronic changes in alcoholism as daily alcohol administration was shown to increase N-methyl-D-aspartic acid receptor activity long-term, and (ii) ethanol has access to the dopaminergic reward system via glycine receptors, being an allosteric modulator of glycine receptors. This manuscript summarises the progress and development of glycine transporter 1 inhibitors, characterizing them by their mode of action, adverse effects, and discusses their clinical applicability. Furthermore, we highlight the progress in the latest clinical trials, outline currently applied treatment methods, and offer suggestions for implementing glycine transporter 1 inhibitors into the long-term treatment of alcohol abuse.
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Affiliation(s)
- Marcell Harhai
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Laszlo G. Harsing, Jr
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
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3
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Santora VJ, Almos TA, Barido R, Basinger J, Bellows CL, Bookser BC, Breitenbucher JG, Broadbent NJ, Cabebe C, Chai CK, Chen M, Chow S, Chung DM, Crickard L, Danks AM, Freestone GC, Gitnick D, Gupta V, Hoffmaster C, Hudson AR, Kaplan AP, Kennedy MR, Lee D, Limberis J, Ly K, Mak CC, Masatsugu B, Morse AC, Na J, Neul D, Nikpur J, Peters M, Petroski RE, Renick J, Sebring K, Sevidal S, Tabatabaei A, Wen J, Yan Y, Yoder ZW, Zook D. Design and Synthesis of Novel and Selective Glycine Transporter-1 (GlyT1) Inhibitors with Memory Enhancing Properties. J Med Chem 2018; 61:6018-6033. [DOI: 10.1021/acs.jmedchem.8b00372] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Vincent J. Santora
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Theresa A. Almos
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Richard Barido
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jillian Basinger
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chris L. Bellows
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Brett C. Bookser
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - J. Guy Breitenbucher
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Nicola J. Broadbent
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Clifford Cabebe
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chih-Kun Chai
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Mi Chen
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Stephine Chow
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - De Michael Chung
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Lindsay Crickard
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Anne M. Danks
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Graeme C. Freestone
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Dany Gitnick
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Varsha Gupta
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Christine Hoffmaster
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Andrew R. Hudson
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Alan P. Kaplan
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Michael R. Kennedy
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Dong Lee
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - James Limberis
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Kiev Ly
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Chi Ching Mak
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Brittany Masatsugu
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Andrew C. Morse
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jim Na
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - David Neul
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - John Nikpur
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Marco Peters
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Robert E. Petroski
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Joel Renick
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Kristen Sebring
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Samantha Sevidal
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Ali Tabatabaei
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Jenny Wen
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Yingzhuo Yan
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Zachary W. Yoder
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
| | - Douglas Zook
- Dart NeuroScience LLC, 12278 Scripps Summit Drive, San Diego, California 92121, United States
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4
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Ghirardini E, Wadle SL, Augustin V, Becker J, Brill S, Hammerich J, Seifert G, Stephan J. Expression of functional inhibitory neurotransmitter transporters GlyT1, GAT-1, and GAT-3 by astrocytes of inferior colliculus and hippocampus. Mol Brain 2018; 11:4. [PMID: 29370841 PMCID: PMC5785846 DOI: 10.1186/s13041-018-0346-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/03/2018] [Indexed: 12/18/2022] Open
Abstract
Neuronal inhibition is mediated by glycine and/or GABA. Inferior colliculus (IC) neurons receive glycinergic and GABAergic inputs, whereas inhibition in hippocampus (HC) predominantly relies on GABA. Astrocytes heterogeneously express neurotransmitter transporters and are expected to adapt to the local requirements regarding neurotransmitter homeostasis. Here we analyzed the expression of inhibitory neurotransmitter transporters in IC and HC astrocytes using whole-cell patch-clamp and single-cell reverse transcription-PCR. We show that most astrocytes in both regions expressed functional glycine transporters (GlyTs). Activation of these transporters resulted in an inward current (IGly) that was sensitive to the competitive GlyT1 agonist sarcosine. Astrocytes exhibited transcripts for GlyT1 but not for GlyT2. Glycine did not alter the membrane resistance (RM) arguing for the absence of functional glycine receptors (GlyRs). Thus, IGly was mainly mediated by GlyT1. Similarly, we found expression of functional GABA transporters (GATs) in all IC astrocytes and about half of the HC astrocytes. These transporters mediated an inward current (IGABA) that was sensitive to the competitive GAT-1 and GAT-3 antagonists NO711 and SNAP5114, respectively. Accordingly, transcripts for GAT-1 and GAT-3 were found but not for GAT-2 and BGT-1. Only in hippocampal astrocytes, GABA transiently reduced RM demonstrating the presence of GABAA receptors (GABAARs). However, IGABA was mainly not contaminated by GABAAR-mediated currents as RM changes vanished shortly after GABA application. In both regions, IGABA was stronger than IGly. Furthermore, in HC the IGABA/IGly ratio was larger compared to IC. Taken together, our results demonstrate that astrocytes are heterogeneous across and within distinct brain areas. Furthermore, we could show that the capacity for glycine and GABA uptake varies between both brain regions.
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Affiliation(s)
- Elsa Ghirardini
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.,Department of Medical Biotechnology and Translational Medicine, University of Milan, via Vanvitelli 32, I-20129, Milan, Italy.,Pharmacology and Brain Pathology Lab, Humanitas Clinical and Research Center, via Manzoni 56, I-20089, Rozzano, Italy
| | - Simon L Wadle
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Vanessa Augustin
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Jasmin Becker
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Sina Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Julia Hammerich
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany
| | - Jonathan Stephan
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.
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Abstract
Glycine, besides exerting essential metabolic functions, is an important inhibitory neurotransmitter in caudal areas of the central nervous system and also a positive neuromodulator at excitatory glutamate-mediated synapses. Glial cells provide metabolic support to neurons and modulate synaptic activity. Six transporters belonging to three solute carrier families (SLC6, SLC38, and SLC7) are capable of transporting glycine across the glial plasma membrane. The unique glial glycine-selective transporter GlyT1 (SLC6) is the main regulator of synaptic glycine concentrations, assisted by the neuronal GlyT2. The five additional glycine transporters ATB0,+, SNAT1, SNAT2, SNAT5, and LAT2 display broad amino acid specificity and have differential contributions to glial glycine transport. Glial glycine transporters are divergent in sequence but share a similar architecture displaying the 5 + 5 inverted fold originally characterized in the leucine transporter LeuT. The availability of protein crystals solved at high resolution for prokaryotic and, more recently, eukaryotic homologues of this superfamily has advanced significantly our understanding of the mechanism of glycine transport.
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6
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Hülsmann S, Mesuret G, Dannenberg J, Arnoldt M, Niebert M. GlyT2-Dependent Preservation of MECP2-Expression in Inhibitory Neurons Improves Early Respiratory Symptoms but Does Not Rescue Survival in a Mouse Model of Rett Syndrome. Front Physiol 2016; 7:385. [PMID: 27672368 PMCID: PMC5018520 DOI: 10.3389/fphys.2016.00385] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/22/2016] [Indexed: 11/25/2022] Open
Abstract
Mutations in methyl-CpG-binding protein 2 (MECP2) gene have been shown to manifest in a neurodevelopmental disorder that is called Rett syndrome. A typical problem that occurs during development is a disturbance of breathing. To address the role of inhibitory neurons, we generated a mouse line that restores MECP2 in inhibitory neurons in the brainstem by crossbreeding a mouse line that expresses the Cre-recombinase (Cre) in inhibitory neurons under the control of the glycine transporter 2 (GlyT2, slc6a5) promotor (GlyT2-Cre) with a mouse line that has a floxed-stop mutation of the Mecp2 gene (Mecp2stop/y). Unrestrained whole-body-plethysmography at postnatal day P60 revealed a low respiratory rate and prolonged respiratory pauses in Mecp2stop/y mice. In contrast, GlyT2-Cre positive Mecp2stop/y mice (Cre+; Mecp2stop/y) showed greatly improved respiration and were indistinguishable from wild type littermates. These data support the concept that alterations in inhibitory neurons are important for the development of the respiratory phenotype in Rett syndrome.
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Affiliation(s)
- Swen Hülsmann
- Clinic for Anesthesiology, University Medical CenterGöttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the BrainGöttingen, Germany
| | - Guillaume Mesuret
- Clinic for Anesthesiology, University Medical CenterGöttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the BrainGöttingen, Germany
| | - Julia Dannenberg
- Clinic for Anesthesiology, University Medical Center Göttingen, Germany
| | - Mauricio Arnoldt
- Clinic for Anesthesiology, University Medical Center Göttingen, Germany
| | - Marcus Niebert
- Center for Nanoscale Microscopy and Molecular Physiology of the BrainGöttingen, Germany; Institute of Neuro- and Sensory Physiology, University Medical Center GöttingenGöttingen, Germany
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7
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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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8
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Norepinephrine-induced calcium signaling in astrocytes in the respiratory network of the ventrolateral medulla. Respir Physiol Neurobiol 2015; 226:18-23. [PMID: 26514085 DOI: 10.1016/j.resp.2015.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 11/22/2022]
Abstract
The neuronal activity in the respiratory network of the ventrolateral medulla strongly depends on a variety of different neuromodulators. Since the respiratory activity generated by neurons in the pre-Bötzinger complex (preBötC) is stabilized by astrocytes, we investigated potential effects of the neuromodulator norepinephrine (NE) on the astrocytic calcium signaling in the ventral respiratory group. In acutely isolated brainstem slices from wild type mice (postnatal day 1-10) we performed calcium imaging experiments using Oregon Green 488 BAPTA-1 AM as a calcium indicator dye. Astrocytes in the preBötC, which were identified by their unique intracellular calcium rise after the reduction of the extracellular K(+) concentration, showed calcium rises in response to norepinephrine. These calcium signals persisted after blockade of neuronal activity by tetrodotoxin (TTX) indicating that they were independent of neuronal activity. Furthermore, application of the endoplasmic reticulum calcium pump blocker cyclopiazonic acid (CPA) diminished norepinephrine-induced calcium signals. This results could be confirmed using transgenic mice with astrocyte specific expression of GCaMP3. Thus, norepinephrine might, apart from acting directly on neurons, influence and modulate respiratory network activity via the modulation of astroglial calcium signaling.
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9
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Astrocyte physiopathology: At the crossroads of intercellular networking, inflammation and cell death. Prog Neurobiol 2015; 130:86-120. [PMID: 25930681 DOI: 10.1016/j.pneurobio.2015.04.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/15/2015] [Accepted: 04/20/2015] [Indexed: 12/11/2022]
Abstract
Recent breakthroughs in neuroscience have led to the awareness that we should revise our traditional mode of thinking and studying the CNS, i.e. by isolating the privileged network of "intelligent" synaptic contacts. We may instead need to contemplate all the variegate communications occurring between the different neural cell types, and centrally involving the astrocytes. Basically, it appears that a single astrocyte should be considered as a core that receives and integrates information from thousands of synapses, other glial cells and the blood vessels. In turn, it generates complex outputs that control the neural circuitry and coordinate it with the local microcirculation. Astrocytes thus emerge as the possible fulcrum of the functional homeostasis of the healthy CNS. Yet, evidence indicates that the bridging properties of the astrocytes can change in parallel with, or as a result of, the morphological, biochemical and functional alterations these cells undergo upon injury or disease. As a consequence, they have the potential to transform from supportive friends and interactive partners for neurons into noxious foes. In this review, we summarize the currently available knowledge on the contribution of astrocytes to the functioning of the CNS and what goes wrong in various pathological conditions, with a particular focus on Amyotrophic Lateral Sclerosis, Alzheimer's Disease and ischemia. The observations described convincingly demonstrate that the development and progression of several neurological disorders involve the de-regulation of a finely tuned interplay between multiple cell populations. Thus, it seems that a better understanding of the mechanisms governing the integrated communication and detrimental responses of the astrocytes as well as their impact towards the homeostasis and performance of the CNS is fundamental to open novel therapeutic perspectives.
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10
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Glutathione-Dependent Detoxification Processes in Astrocytes. Neurochem Res 2014; 40:2570-82. [PMID: 25428182 DOI: 10.1007/s11064-014-1481-1] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/10/2014] [Accepted: 11/15/2014] [Indexed: 01/17/2023]
Abstract
Astrocytes have a pivotal role in brain as partners of neurons in homeostatic and metabolic processes. Astrocytes also protect other types of brain cells against the toxicity of reactive oxygen species and are considered as first line of defence against the toxic potential of xenobiotics. A key component in many of the astrocytic detoxification processes is the tripeptide glutathione (GSH) which serves as electron donor in the GSH peroxidase-catalyzed reduction of peroxides. In addition, GSH is substrate in the detoxification of xenobiotics and endogenous compounds by GSH-S-transferases which generate GSH conjugates that are efficiently exported from the cells by multidrug resistance proteins. Moreover, GSH reacts with the reactive endogenous carbonyls methylglyoxal and formaldehyde to intermediates which are substrates of detoxifying enzymes. In this article we will review the current knowledge on the GSH metabolism of astrocytes with a special emphasis on GSH-dependent detoxification processes.
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11
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Stephan J, Friauf E. Functional analysis of the inhibitory neurotransmitter transporters GlyT1, GAT-1, and GAT-3 in astrocytes of the lateral superior olive. Glia 2014; 62:1992-2003. [PMID: 25103283 DOI: 10.1002/glia.22720] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 06/26/2014] [Accepted: 06/27/2014] [Indexed: 01/03/2023]
Abstract
Neurotransmitter clearance from the synaptic cleft is a major function of astrocytes and requires neurotransmitter transporters. In the rodent lateral superior olive (LSO), a conspicuous auditory brainstem center, both glycine and GABA mediate synaptic inhibition. However, the main inhibitory input from the medial nucleus of the trapezoid body (MNTB) appears to be glycinergic by postnatal day (P) 14, when circuit maturation is almost accomplished. Using whole-cell patch-clamp recordings at P3-20, we analyzed glycine transporters (GlyT1) and GABA transporters (GAT-1, GAT-3) in mouse LSO astrocytes, emphasizing on their developmental regulation. Application of glycine or GABA induced a dose- and age-dependent inward current and a respective depolarization. The GlyT1-specific inhibitor sarcosine reduced the maximal glycine-induced current (IGly (max) ) by about 60%. The GAT-1 and GAT-3 antagonists NO711 and SNAP5114, respectively, reduced the maximal GABA-induced current (IGABA (max) ) by about 35%. Furthermore, [Cl(-) ]o reduction decreased IGly (max) and IGABA (max) by about 85 to 95%, showing the Cl(-) dependence of GlyT and GAT. IGABA (max) was stronger than IGly (max) , and the ratio increased developmentally from 1.6-fold to 3.7-fold. Together, our results demonstrate the functional presence of the three inhibitory neurotransmitter transporters GlyT1, GAT-1, and GAT-3 in LSO astrocytes. Furthermore, the uptake capability for GABA was higher than for glycine, pointing toward eminent GABAergic signaling in the LSO. GABA may originate from another source than the MNTB-LSO synapses, namely from another projection or from reversal of astrocytic GATs. Thus, neuronal signaling in the LSO appears to be more versatile than previously thought. GLIA 2014;62:1992-2003.
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Affiliation(s)
- Jonathan Stephan
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Kaiserslautern, Germany
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12
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The multispecific thyroid hormone transporter OATP1C1 mediates cell-specific sulforhodamine 101-labeling of hippocampal astrocytes. Brain Struct Funct 2013; 220:193-203. [PMID: 24129767 PMCID: PMC4286632 DOI: 10.1007/s00429-013-0645-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 09/23/2013] [Indexed: 12/21/2022]
Abstract
Sulforhodamine 101 (SR101) is widely used for astrocyte identification, though the labeling mechanism remains unknown and the efficacy of labeling in different brain regions is heterogeneous. By combining region-specific isolation of astrocytes followed by transcriptome analysis, two-photon excitation microscopy, and mouse genetics, we identified the thyroid hormone transporter OATP1C1 as the SR101-uptake transporter in hippocampus and cortex.
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13
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Okada Y, Sasaki T, Oku Y, Takahashi N, Seki M, Ujita S, Tanaka KF, Matsuki N, Ikegaya Y. Preinspiratory calcium rise in putative pre-Botzinger complex astrocytes. J Physiol 2012; 590:4933-44. [PMID: 22777672 DOI: 10.1113/jphysiol.2012.231464] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The neural inspiratory activity originates from a ventrolateral medullary region called the pre-Bötzinger complex (preBötC), yet the mechanism underlying respiratory rhythmogenesis is not completely understood. Recently, the role of not only neurons but astrocytes in the central respiratory control has attracted considerable attention. Here we report our discovery that an intracellular calcium rise in a subset of putative astrocytes precedes inspiratory neuronal firing in rhythmically active slices. Functional calcium imaging from hundreds of preBötC cells revealed that a subset of putative astrocytes exhibited rhythmic calcium elevations preceding inspiratory neuronal activity with a time lag of approximately 2 s. These preinspiratory putative astrocytes maintained their rhythmic activities even during the blockade of neuronal activity with tetrodotoxin, whereas the rhythm frequency was lowered and the intercellular phases of these rhythms were decoupled. In addition, optogenetic stimulation of preBötC putative astrocytes induced firing of inspiratory neurons. These findings raise the possibility that astrocytes in the preBötC are actively involved in respiratory rhythm generation in rhythmically active slices.
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Affiliation(s)
- Yasumasa Okada
- Division of Internal Medicine and Laboratory of Electrophysiology, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
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14
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Zhang Y, Barres BA. Astrocyte heterogeneity: an underappreciated topic in neurobiology. Curr Opin Neurobiol 2010; 20:588-94. [PMID: 20655735 DOI: 10.1016/j.conb.2010.06.005] [Citation(s) in RCA: 410] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 05/26/2010] [Accepted: 06/26/2010] [Indexed: 11/29/2022]
Abstract
Astrocytes, one of the most numerous types of cells in the central nervous system, are crucial for potassium homeostasis, neurotransmitter uptake, synapse formation, regulation of blood-brain-barrier, and the development of the nervous system. Historically, astrocytes have been studied as a homogeneous group of cells. However, evidence has accumulated that suggests heterogeneity of astrocytes across brain regions as well as within the same brain regions. Astrocytes differ in their morphology, developmental origin, gene expression profile, physiological properties, function, and response to injury and disease. A better understanding of the heterogeneity of astrocytes will greatly aid investigation of the function of astrocytes in normal brain as well as the roles of astrocytes in neurological disorders.
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Affiliation(s)
- Ye Zhang
- Department of Neurobiology, Stanford University, Stanford, CA 94305-5125, USA.
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Kopec K, Flood DG, Gasior M, McKenna BAW, Zuvich E, Schreiber J, Salvino JM, Durkin JT, Ator MA, Marino MJ. Glycine transporter (GlyT1) inhibitors with reduced residence time increase prepulse inhibition without inducing hyperlocomotion in DBA/2 mice. Biochem Pharmacol 2010; 80:1407-17. [PMID: 20637735 DOI: 10.1016/j.bcp.2010.07.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 07/02/2010] [Accepted: 07/06/2010] [Indexed: 12/25/2022]
Abstract
Inhibition of the glycine transporter type 1 (GlyT1) leading to potentiation of the glycine site (GlyB) on the N-methyl-d-aspartate (NMDA) receptor has been proposed as a novel therapeutic approach for schizophrenia. However, sarcosine-based GlyT1 inhibitors produce undesirable side effects including compulsive walking and respiratory distress. The influence of specific biochemical properties of GlyT1 inhibitors, such as mode of inhibition and residence time, on adverse effects is unknown. Two GlyT1 inhibitors that contain a sarcosine moiety, sarcosine and ALX-5407, and two compounds that do not contain a sarcosine moiety, Roche-7 and Merck (S)-13h, were evaluated for their potency, mode of inhibition, and target residence times in vitro, and modulation of prepulse inhibition (PPI) and locomotor activity in vivo. (S)-13h and sarcosine were competitive inhibitors while ALX-5407 and Roche-7 demonstrated mixed noncompetitive inhibition. Potency of GlyT1 inhibition (ALX-5407>(S)-13h>Roche-7≫sarcosine) did not correlate with residence time on GlyT1 (sarcosine=Roche-7≪(S)-13h<ALX-5407). ALX-5407 and (S)-13h induced compulsive walking, termed obstinate progression (OP), at doses that increased PPI in DBA/2 mice, demonstrating that OP was not a function of mode of inhibition or inhibitor chemotype. Sarcosine and Roche-7 increased PPI without inducing OP, suggesting that compounds with decreased GlyT1 residence time were efficacious without adverse effects. Direct activation of the GlyB site by d-serine did not produce OP. However, OP induced by (S)-13h was blocked by strychnine, a glycine receptor (GlyA) antagonist, suggesting that OP induced by GlyT1 inhibition was mediated by GlyA. Thus, GlyT1 inhibitors with short residence times demonstrated efficacy without mechanism-based adverse effects.
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Affiliation(s)
- Karla Kopec
- Cephalon, Inc., West Chester, PA 19380, USA.
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Ruangkittisakul A, Okada Y, Oku Y, Koshiya N, Ballanyi K. Fluorescence imaging of active respiratory networks. Respir Physiol Neurobiol 2009; 168:26-38. [DOI: 10.1016/j.resp.2009.02.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 02/11/2009] [Accepted: 02/20/2009] [Indexed: 11/17/2022]
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Hewett JA. Determinants of regional and local diversity within the astroglial lineage of the normal central nervous system. J Neurochem 2009; 110:1717-36. [PMID: 19627442 DOI: 10.1111/j.1471-4159.2009.06288.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Astrocytes are a major component of the resident non-neuronal glial cell population of the CNS. They are ubiquitously distributed throughout the brain and spinal cord, where they were initially thought to function in both structural and homeostatic capacities, providing the framework and environment in which neurons performed their parenchymal duties. However, this stroma-like view of astrocytes is no longer satisfactory. Mounting evidence particularly within the last decade indicates that astrocytes do not simply support neuronal activity but directly contribute to it. Congruent with this evolving view of astrocyte function in information processing is the emergent notion that these glial cells are not a homogeneous population of cells. Thus, astrocytes in various anatomically distinct regions of the normal CNS possess unique phenotypic characteristics that may directly influence the particular neuronal activities that define these regions. Remarkably, regional populations of astrocytes appear to exhibit local heterogeneity as well. Many phenotypic traits of the astrocyte lineage are responsive to local environmental cues (i.e., are adaptable), suggesting that plasticity contributes to this diversity. However, compelling evidence suggests that astrocytes arise from multiple distinct progenitor pools in the developing CNS, raising the intriguing possibility that some astrocyte heterogeneity may result from intrinsic differences between these progenitors. The purpose of this review is to explore the evidence for and mechanistic determinants of regional and local astrocyte diversity.
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Affiliation(s)
- James A Hewett
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, USA.
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Härtel K, Schnell C, Hülsmann S. Astrocytic calcium signals induced by neuromodulators via functional metabotropic receptors in the ventral respiratory group of neonatal mice. Glia 2009; 57:815-27. [DOI: 10.1002/glia.20808] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Structure-function analysis of rhythmogenic inspiratory pre-Bötzinger complex networks in "calibrated" newborn rat brainstem slices. Respir Physiol Neurobiol 2009; 168:158-78. [PMID: 19406253 DOI: 10.1016/j.resp.2009.04.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 04/14/2009] [Accepted: 04/22/2009] [Indexed: 11/20/2022]
Abstract
Inspiratory pre-Bötzinger complex (preBötC) networks remain active in perinatal rodent brainstem slices. Our analysis of (crescendo-like) inspiratory-related population and cellular bursting in novel histologically identified transversal preBötC slices in physiological (3 mM) superfusate [K(+)] revealed: (i) the preBötC extent sufficient for rhythm in thin slices is at most 175 microm. (ii) In 700 microm thick slices with unilaterally exposed preBötC, a <100 microm kernel generates a eupnea-like inspiratory pattern under predominant influence of caudally adjacent structures or thyrotropin-releasing hormone-like transmitters, but a mixed eupnea-sigh-like pattern when influence of rostral structures or substance-P-like transmitters dominates. (iii) Primarily presynaptic processes may underlie inhibition of rhythm by opioids or raising superfusate [Ca(2+)] from lower to upper physiological limits (1-1.5 mM). (iv) High K(+) reverses depression of rhythm by raised Ca(2+), opioids and anoxia. In summary, distinct activity patterns of spatiochemically organized isolated inspiratory networks depend on both an extracellular "Ca(2+)-K(+) antagonism" and slice dimensions. This explains some discrepant findings between studies and suggests use of "calibrated" slices and more uniform experimental conditions.
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Hirrlinger PG, Wurm A, Hirrlinger J, Bringmann A, Reichenbach A. Osmotic swelling characteristics of glial cells in the murine hippocampus, cerebellum, and retina in situ. J Neurochem 2008; 105:1405-17. [DOI: 10.1111/j.1471-4159.2008.05243.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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