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Petravicz J, Boyt KM, McCarthy KD. Astrocyte IP3R2-dependent Ca(2+) signaling is not a major modulator of neuronal pathways governing behavior. Front Behav Neurosci 2014; 8:384. [PMID: 25429263 PMCID: PMC4228853 DOI: 10.3389/fnbeh.2014.00384] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022] Open
Abstract
Calcium-dependent release of gliotransmitters by astrocytes is reported to play a critical role in synaptic transmission and be necessary for long-term potentiation (LTP), long-term depression (LTD) and other forms of synaptic modulation that are correlates of learning and memory. Further, physiological processes reported to be dependent on Ca2+ fluxes in astrocytes include functional hyperemia, sleep, and regulation of breathing. The preponderance of findings indicate that most, if not all, receptor dependent Ca2+ fluxes within astrocytes are due to release of Ca2+ through IP3 receptor/channels in the endoplasmic reticulum. Findings from several laboratories indicate that astrocytes only express IP3 receptor type 2 (IP3R2) and that a knockout of IP3R2 obliterates the GPCR-dependent astrocytic Ca2+ responses. Assuming that astrocytic Ca2+ fluxes play a critical role in synaptic physiology, it would be predicted that elimination of astrocytic Ca2+ fluxes would lead to marked changes in behavioral tests. Here, we tested this hypothesis by conducting a broad series of behavioral tests that recruited multiple brain regions, on an IP3R2 conditional knockout mouse model. We present the novel finding that behavioral processes are unaffected by lack of astrocyte IP3R-mediated Ca2+ signals. IP3R2 cKO animals display no change in anxiety or depressive behaviors, and no alteration to motor and sensory function. Morris water maze testing, a behavioral correlate of learning and memory, was unaffected by lack of astrocyte IP3R2-mediated Ca2+-signaling. Therefore, in contrast to the prevailing literature, we find that neither receptor-driven astrocyte Ca2+ fluxes nor, by extension, gliotransmission is likely to be a major modulating force on the physiological processes underlying behavior.
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Affiliation(s)
- Jeremy Petravicz
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Kristen M Boyt
- Department of Pharmacology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Ken D McCarthy
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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102
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Perea G, Sur M, Araque A. Neuron-glia networks: integral gear of brain function. Front Cell Neurosci 2014; 8:378. [PMID: 25414643 PMCID: PMC4222327 DOI: 10.3389/fncel.2014.00378] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/22/2014] [Indexed: 12/21/2022] Open
Abstract
Astrocytes, the most abundant glial cell in the brain, play critical roles in metabolic and homeostatic functions of the Nervous System; however, their participation in coding information and cognitive processes has been largely ignored. The strategic position of astrocyte processes facing synapses and the astrocyte ability to uptake neurotransmitters and release neuroactive substances, so-called “gliotransmitters”, provide the scenario for prolific neuron-astrocyte signaling. From studies at single-cell level to animal behavior, recent advances in technology and genetics have revealed the impact of astrocyte activity in brain function from cellular and synaptic physiology, neuronal circuits to behavior. The present review critically discusses the consequences of astrocyte signaling on synapses and networks, as well as its impact on neuronal information processing, showing that some crucial brain functions arise from the coordinated activity of neuron-glia networks.
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Affiliation(s)
- Gertrudis Perea
- Functional and System Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Mriganka Sur
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology Cambridge, MA, USA
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis MN, USA
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103
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Rat nucleus accumbens core astrocytes modulate reward and the motivation to self-administer ethanol after abstinence. Neuropsychopharmacology 2014; 39:2835-45. [PMID: 24903651 PMCID: PMC4200494 DOI: 10.1038/npp.2014.135] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 05/03/2014] [Accepted: 06/03/2014] [Indexed: 11/08/2022]
Abstract
Our understanding of the active role that astrocytes play in modulating neuronal function and behavior is rapidly expanding, but little is known about the role that astrocytes may play in drug-seeking behavior for commonly abused substances. Given that the nucleus accumbens is critically involved in substance abuse and motivation, we sought to determine whether nucleus accumbens astrocytes influence the motivation to self-administer ethanol following abstinence. We found that the packing density of astrocytes that were expressing glial fibrillary acidic protein increased in the nucleus accumbens core (NAcore) during abstinence from EtOH self-administration. No change was observed in the nucleus accumbens shell. This increased NAcore astrocyte density positively correlated with the motivation for ethanol. Astrocytes can communicate with one another and influence neuronal activity through gap-junction hemichannels. Because of this, the effect of blocking gap-junction hemichannels on the motivation for ethanol was examined. The motivation to self-administer ethanol after 3 weeks abstinence was increased following microinjection of gap-junction hemichannel blockers into the NAcore at doses that block both neuronal and astrocytic channels. In contrast, no effect was observed following microinjection of doses that are not thought to block astrocytic channels or following microinjection of either dose into the nucleus accumbens shell. Additionally, the motivation for sucrose after 3 weeks abstinence was unaffected by NAcore gap-junction hemichannel blockers. Next, Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) were selectively expressed in NAcore astrocytes to test the effect of astrocyte stimulation. DREADD activation increased cytosolic calcium in primary astrocytes, facilitated responding for rewarding brain stimulation, and reduced the motivation for ethanol after 3 weeks abstinence. This is the first work to modulate drug-seeking behavior with astrocyte-specific DREADDs. Taken together, our findings demonstrate that NAcore astrocytes can shape the motivation to self-administer ethanol; suggesting that the development of ligands which selectively stimulate astrocytes may be a successful strategy to abate ethanol-seeking behavior.
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104
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Berlinguer-Palmini R, Narducci R, Merhan K, Dilaghi A, Moroni F, Masi A, Scartabelli T, Landucci E, Sili M, Schettini A, McGovern B, Maskaant P, Degenaar P, Mannaioni G. Arrays of microLEDs and astrocytes: biological amplifiers to optogenetically modulate neuronal networks reducing light requirement. PLoS One 2014; 9:e108689. [PMID: 25265500 PMCID: PMC4180921 DOI: 10.1371/journal.pone.0108689] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/23/2014] [Indexed: 01/08/2023] Open
Abstract
In the modern view of synaptic transmission, astrocytes are no longer confined to the role of merely supportive cells. Although they do not generate action potentials, they nonetheless exhibit electrical activity and can influence surrounding neurons through gliotransmitter release. In this work, we explored whether optogenetic activation of glial cells could act as an amplification mechanism to optical neural stimulation via gliotransmission to the neural network. We studied the modulation of gliotransmission by selective photo-activation of channelrhodopsin-2 (ChR2) and by means of a matrix of individually addressable super-bright microLEDs (μLEDs) with an excitation peak at 470 nm. We combined Ca2+ imaging techniques and concurrent patch-clamp electrophysiology to obtain subsequent glia/neural activity. First, we tested the μLEDs efficacy in stimulating ChR2-transfected astrocyte. ChR2-induced astrocytic current did not desensitize overtime, and was linearly increased and prolonged by increasing μLED irradiance in terms of intensity and surface illumination. Subsequently, ChR2 astrocytic stimulation by broad-field LED illumination with the same spectral profile, increased both glial cells and neuronal calcium transient frequency and sEPSCs suggesting that few ChR2-transfected astrocytes were able to excite surrounding not-ChR2-transfected astrocytes and neurons. Finally, by using the μLEDs array to selectively light stimulate ChR2 positive astrocytes we were able to increase the synaptic activity of single neurons surrounding it. In conclusion, ChR2-transfected astrocytes and μLEDs system were shown to be an amplifier of synaptic activity in mixed corticalneuronal and glial cells culture.
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Affiliation(s)
- Rolando Berlinguer-Palmini
- School of Electric and Electronic Engineering – Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom
| | - Roberto Narducci
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Kamyar Merhan
- School of Electric and Electronic Engineering – Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom
| | - Arianna Dilaghi
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Flavio Moroni
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Alessio Masi
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Tania Scartabelli
- Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Elisa Landucci
- Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Maria Sili
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Antonio Schettini
- Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Brian McGovern
- Institute of Biomedical Engineering, Imperial College, London, United Kingdom
| | | | - Patrick Degenaar
- School of Electric and Electronic Engineering – Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom
| | - Guido Mannaioni
- Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
- * E-mail:
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105
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Figueiredo M, Lane S, Stout RF, Liu B, Parpura V, Teschemacher AG, Kasparov S. Comparative analysis of optogenetic actuators in cultured astrocytes. Cell Calcium 2014; 56:208-14. [PMID: 25109549 PMCID: PMC4169180 DOI: 10.1016/j.ceca.2014.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022]
Abstract
We compared six optogenetic tools to selectively stimulate and study astrocytes. Channelrhodopsin-2 variants cause release of Ca2+ from intracellular stores. Opto-GPCRs activate selective second messenger cascades, leading to [Ca2+]i rises. Autocrine action of ATP mediates the bulk of [Ca2+]i signals evoked by opto-GPCRs. Current optogenetic tools initiate relevant signalling events in astrocytes.
Astrocytes modulate synaptic transmission via release of gliotransmitters such as ATP, glutamate, d-serine and l-lactate. One of the main problems when studying the role of astrocytes in vitro and in vivo is the lack of suitable tools for their selective activation. Optogenetic actuators can be used to manipulate astrocytic activity by expression of variants of channelrhodopsin-2 (ChR2) or other optogenetic actuators with the aim to initiate intracellular events such as intracellular Ca2+ ([Ca2+]i) and/or cAMP increases. We have developed an array of adenoviral vectors (AVV) with ChR2-like actuators, including an enhanced ChR2 mutant (H134R), and a mutant with improved Ca2+ permeability (Ca2+ translocating channelrhodopsin, CatCh). We show here that [Ca2+]i elevations evoked by ChR2(H134R) and CatCh in astrocytes are largely due to release of Ca2+ from the intracellular stores. The autocrine action of ATP which is released under these conditions and acts on the P2Y receptors also contributes to the [Ca2+]i elevations. We also studied effects evoked using light-sensitive G-protein coupled receptors (opto-adrenoceptors). Activation of optoα1AR (Gq-coupled) and optoβ2AR (Gs-coupled) resulted in astrocytic [Ca2+]i increases which were suppressed by blocking the corresponding intracellular signalling cascade (phospholipase C and adenylate cyclase, respectively). Interestingly, the bulk of [Ca2+]i responses evoked using either optoAR was blocked by an ATP degrading enzyme, apyrase, or a P2Y1 receptor blocker, MRS 2179, indicating that they are to a large extent triggered by the autocrine action of ATP. We conclude that, whilst optimal tools for control of astrocytes are yet to be generated, the currently available optogenetic actuators successfully initiate biologically relevant signalling events in astrocytes.
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Affiliation(s)
- Melina Figueiredo
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Samantha Lane
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Randy F Stout
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama, Birmingham, AL 35294, USA; The Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Beihui Liu
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama, Birmingham, AL 35294, USA; Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Anja G Teschemacher
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK.
| | - Sergey Kasparov
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD, UK.
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106
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Han VZ, Magnus G, Zhang Y, Wei AD, Turner EE. Bidirectional modulation of deep cerebellar nuclear cells revealed by optogenetic manipulation of inhibitory inputs from Purkinje cells. Neuroscience 2014; 277:250-66. [PMID: 25020121 DOI: 10.1016/j.neuroscience.2014.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 01/25/2023]
Abstract
In the mammalian cerebellum, deep cerebellar nuclear (DCN) cells convey all information from cortical Purkinje cells (PCs) to premotor nuclei and other brain regions. However, how DCN cells integrate inhibitory input from PCs with excitatory inputs from other sources has been difficult to assess, in part due to the large spatial separation between cortical PCs and their target cells in the nuclei. To circumvent this problem we have used a Cre-mediated genetic approach to generate mice in which channelrhodopsin-2 (ChR2), fused with a fluorescent reporter, is selectively expressed by GABAergic neurons, including PCs. In recordings from brain slice preparations from this model, mammalian PCs can be robustly depolarized and discharged by brief photostimulation. In recordings of postsynaptic DCN cells, photostimulation of PC axons induces a strong inhibition that resembles these cells' responses to focal electrical stimulation, but without a requirement for the glutamate receptor blockers typically applied in such experiments. In this optogenetic model, laser pulses as brief as 1 ms can reliably induce an inhibition that shuts down the spontaneous spiking of a DCN cell for ∼50 ms. If bursts of such brief light pulses are delivered, a fixed pattern of bistable bursting emerges. If these pulses are delivered continuously to a spontaneously bistable cell, the immediate response to such photostimulation is inhibitory in the cell's depolarized state and excitatory when the membrane has repolarized; a less regular burst pattern then persists after stimulation has been terminated. These results indicate that the spiking activity of DCN cells can be bidirectionally modulated by the optically activated synaptic inhibition of cortical PCs.
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Affiliation(s)
- V Z Han
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, United States.
| | - G Magnus
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, United States
| | - Y Zhang
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, United States; Department of Pediatrics and Neuroscience, Xijing Hospital, Xi'an 710032, China
| | - A D Wei
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, United States; Department of Neurological Surgery, University of Washington, Seattle, WA 98101, United States
| | - E E Turner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, United States; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, United States; Center on Human Development and Disability, University of Washington, Seattle, WA 98195, United States
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107
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Sohal HS, Jackson A, Jackson R, Clowry GJ, Vassilevski K, O'Neill A, Baker SN. The sinusoidal probe: a new approach to improve electrode longevity. FRONTIERS IN NEUROENGINEERING 2014; 7:10. [PMID: 24808859 PMCID: PMC4010751 DOI: 10.3389/fneng.2014.00010] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 04/07/2014] [Indexed: 11/13/2022]
Abstract
Micromotion between the brain and implanted electrodes is a major contributor to the failure of invasive brain-machine interfaces. Movements of the electrode tip cause recording instabilities while spike amplitudes decline over the weeks/months post-implantation due to glial cell activation caused by sustained mechanical trauma. We have designed a sinusoidal probe in order to reduce movement of the recording tip relative to the surrounding neural tissue. The probe was microfabricated from flexible materials and incorporated a sinusoidal shaft to minimize tethering forces and a 3D spheroid tip to anchor the recording site within the brain. Compared to standard microwire electrodes, the signal-to-noise ratio and local field potential power of sinusoidal probe recordings from rabbits was more stable across recording periods up to 678 days. Histological quantification of microglia and astrocytes showed reduced neuronal tissue damage especially for the tip region between 6 and 24 months post-implantation. We suggest that the micromotion-reducing measures incorporated into our design, at least partially, decreased the magnitude of gliosis, resulting in enhanced longevity of recording.
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Affiliation(s)
- Harbaljit S Sohal
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK ; School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Andrew Jackson
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
| | - Richard Jackson
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Gavin J Clowry
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
| | - Konstantin Vassilevski
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Anthony O'Neill
- School of Electrical and Electronic Engineering, Newcastle University Newcastle Upon Tyne, UK
| | - Stuart N Baker
- Newcastle Movement Lab, Institute of Neuroscience, Newcastle University Newcastle Upon Tyne, UK
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108
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Shibasaki K, Ikenaka K, Tamalu F, Tominaga M, Ishizaki Y. A novel subtype of astrocytes expressing TRPV4 (transient receptor potential vanilloid 4) regulates neuronal excitability via release of gliotransmitters. J Biol Chem 2014; 289:14470-80. [PMID: 24737318 DOI: 10.1074/jbc.m114.557132] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Astrocytes play active roles in the regulation of synaptic transmission. Neuronal excitation can evoke Ca(2+) transients in astrocytes, and these Ca(2+) transients can modulate neuronal excitability. Although only a subset of astrocytes appears to communicate with neurons, the types of astrocytes that can regulate neuronal excitability are poorly characterized. We found that ∼30% of astrocytes in the brain express transient receptor potential vanilloid 4 (TRPV4), indicating that astrocytic subtypes can be classified on the basis of their expression patterns. When TRPV4(+) astrocytes are activated by ligands such as arachidonic acid, the activation propagates to neighboring astrocytes through gap junctions and by ATP release from the TRPV4(+) astrocytes. After activation, both TRPV4(+) and TRPV4(-) astrocytes release glutamate, which acts as an excitatory gliotransmitter to increase synaptic transmission through type 1 metabotropic glutamate receptor (mGluR). Our results indicate that TRPV4(+) astrocytes constitute a novel subtype of the population and are solely responsible for initiating excitatory gliotransmitter release to enhance synaptic transmission. We propose that TRPV4(+) astrocytes form a core of excitatory glial assembly in the brain and function to efficiently increase neuronal excitation in response to endogenous TRPV4 ligands.
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Affiliation(s)
- Koji Shibasaki
- From the Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan,
| | - Kazuhiro Ikenaka
- Division of Neurobiology Neuroinformatics, Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Fuminobu Tamalu
- Department of Physiology, Saitama Medical University, Moroyama 350-0495, Japan
| | - Makoto Tominaga
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan, Division of Cell Signaling, National Institute for Physiological Sciences, and
| | - Yasuki Ishizaki
- From the Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
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109
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Tanaka K. [Development of transgenic animals in optogenetics]. Nihon Yakurigaku Zasshi 2014; 143:193-7. [PMID: 24717608 DOI: 10.1254/fpj.143.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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110
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Beppu K, Sasaki T, Tanaka KF, Yamanaka A, Fukazawa Y, Shigemoto R, Matsui K. Optogenetic countering of glial acidosis suppresses glial glutamate release and ischemic brain damage. Neuron 2014; 81:314-20. [PMID: 24462096 DOI: 10.1016/j.neuron.2013.11.011] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2013] [Indexed: 12/31/2022]
Abstract
The brain demands high-energy supply and obstruction of blood flow causes rapid deterioration of the healthiness of brain cells. Two major events occur upon ischemia: acidosis and liberation of excess glutamate, which leads to excitotoxicity. However, cellular source of glutamate and its release mechanism upon ischemia remained unknown. Here we show a causal relationship between glial acidosis and neuronal excitotoxicity. As the major cation that flows through channelrhodopsin-2 (ChR2) is proton, this could be regarded as an optogenetic tool for instant intracellular acidification. Optical activation of ChR2 expressed in glial cells led to glial acidification and to release of glutamate. On the other hand, glial alkalization via optogenetic activation of a proton pump, archaerhodopsin (ArchT), led to cessation of glutamate release and to the relief of ischemic brain damage in vivo. Our results suggest that controlling glial pH may be an effective therapeutic strategy for intervention of ischemic brain damage.
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Affiliation(s)
- Kaoru Beppu
- Division of Cerebral Structure, National Institute for Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan; Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan
| | - Takuya Sasaki
- Division of Cerebral Structure, National Institute for Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo 160-8582, Japan
| | - Akihiro Yamanaka
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan
| | - Yugo Fukazawa
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan; Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan; IST Austria, 3400 Klosterneuburg, Austria
| | - Ko Matsui
- Division of Cerebral Structure, National Institute for Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan; Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan; Division of Interdisciplinary Medical Science, Center for Neuroscience, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
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111
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Yamashita A, Hamada A, Suhara Y, Kawabe R, Yanase M, Kuzumaki N, Narita M, Matsui R, Okano H, Narita M. Astrocytic activation in the anterior cingulate cortex is critical for sleep disorder under neuropathic pain. Synapse 2014; 68:235-47. [DOI: 10.1002/syn.21733] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/09/2014] [Indexed: 01/21/2023]
Affiliation(s)
- Akira Yamashita
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Asami Hamada
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Yuki Suhara
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Rui Kawabe
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Makoto Yanase
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Naoko Kuzumaki
- Department of Physiology; Keio University School of Medicine; 35 Shinanomachi Shinjuku-ku Tokyo 160-8582 Japan
| | - Michiko Narita
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
| | - Ryosuke Matsui
- Department of Molecular and Systems Biology; Graduate School of Biostudies, Kyoto University; Yoshida Sakyo-ku Kyoto 606-8501 Japan
| | - Hideyuki Okano
- Department of Physiology; Keio University School of Medicine; 35 Shinanomachi Shinjuku-ku Tokyo 160-8582 Japan
| | - Minoru Narita
- Department of Pharmacology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; 2-4-41 Ebara Shinagawa-ku Tokyo 142-8501 Japan
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112
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Herman AM, Huang L, Murphey DK, Garcia I, Arenkiel BR. Cell type-specific and time-dependent light exposure contribute to silencing in neurons expressing Channelrhodopsin-2. eLife 2014; 3:e01481. [PMID: 24473077 PMCID: PMC3904216 DOI: 10.7554/elife.01481] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Channelrhodopsin-2 (ChR2) has quickly gained popularity as a powerful tool for eliciting genetically targeted neuronal activation. However, little has been reported on the response kinetics of optogenetic stimulation across different neuronal subtypes. With excess stimulation, neurons can be driven into depolarization block, a state where they cease to fire action potentials. Herein, we demonstrate that light-induced depolarization block in neurons expressing ChR2 poses experimental challenges for stable activation of specific cell types and may confound interpretation of experiments when ‘activated’ neurons are in fact being functionally silenced. We show both ex vivo and in vivo that certain neuronal subtypes targeted for ChR2 expression become increasingly susceptible to depolarization block as the duration of light pulses are increased. We find that interneuron populations have a greater susceptibility to this effect than principal excitatory neurons, which are more resistant to light-induced depolarization block. Our results highlight the need to empirically determine the photo-response properties of targeted neurons when using ChR2, particularly in studies designed to elicit complex circuit responses in vivo where neuronal activity will not be recorded simultaneous to light stimulation. DOI:http://dx.doi.org/10.7554/eLife.01481.001 The brain is a highly complex structure composed of trillions of interconnecting nerve cells. The pattern of connections between these cells gives rise to the various brain circuits that govern how the brain functions. Understanding how the brain is wired together is important for determining how ‘faulty circuits’ contribute to various neurological disorders. New optogenetic technique tools allow neuroscientists to turn on specific neurons simply by shining light on them. These techniques involve genetically manipulating the organisms so that their neurons express proteins that are activated when they are exposed to light of a particular wavelength. However, it is important to understand the limitations of this approach—including the possibility that the light might actually turn off some neurons—when using it to study animal behavior. Now, Herman, Huang et al. show that shining light pulses for long durations onto neurons expressing a light-activated protein called channelrhodopsin-2 causes the neurons to become silenced rather than activated. Moreover, certain types of neurons, called interneurons, are more susceptible to this effect—termed ‘depolarization block’—than the other types of neurons. Researchers need to be mindful of this effect when channelrhodopsin-2 is used in optogenetic experiments to study the behavior of living animals. However, this silencing property could be useful in experiments that investigate situations in which depolarization block is thought to contribute to brain function and health: such as in the treatments of schizophrenia and Parkinson’s disease. DOI:http://dx.doi.org/10.7554/eLife.01481.002
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Affiliation(s)
- Alexander M Herman
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
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113
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Chen Y, Mancuso J, Zhao Z, Li X, Cheng J, Roman G, Wong STC. Vasodilation by in vivo activation of astrocyte endfeet via two-photon calcium uncaging as a strategy to prevent brain ischemia. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:126012. [PMID: 24343443 PMCID: PMC3865896 DOI: 10.1117/1.jbo.18.12.126012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/04/2013] [Accepted: 11/05/2013] [Indexed: 06/03/2023]
Abstract
Decreased cerebral blood flow causes brain ischemia and plays an important role in the pathophysiology of many neurodegenerative diseases, including Alzheimer's disease and vascular dementia. In this study, we photomodulated astrocytes in the live animal by a combination of two-photon calcium uncaging in the astrocyte endfoot and in vivo imaging of neurovasculature and astrocytes by intravital two-photon microscopy after labeling with cell type specific fluorescent dyes. Our study demonstrates that photomodulation at the endfoot of a single astrocyte led to a 25% increase in the diameter of a neighboring arteriole, which is a crucial factor regulating cerebral microcirculation in downstream capillaries. Two-photon uncaging in the astrocyte soma or endfoot near veins does not show the same effect on microcirculation. These experimental results suggest that infrared photomodulation on astrocyte endfeet may be a strategy to increase cerebral local microcirculation and thus prevent brain ischemia.
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Affiliation(s)
- Yuanxin Chen
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
| | - James Mancuso
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
| | - Zhen Zhao
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
- Southeast University, Zhongda Hospital, Medical School, Department of Radiology, Jiangsu Key Laboratory of Molecular and Functional Imaging, Nanjing 210009, China
| | - Xuping Li
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
| | - Jie Cheng
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
| | - Gustavo Roman
- Weill Cornell Medical College, Houston Methodist Hospital, Nantz National Alzheimer Center, Houston, Texas 77030
| | - Stephen T. C. Wong
- Weill Cornell Medical College, Houston Methodist Research Institute, \Systems Medicine and Bioengineering Department, TT and WF Chao Center for BRAIN, Houston, Texas 77030
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114
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Xie YF, Jackson MF, MacDonald JF. Optogenetics and synaptic plasticity. Acta Pharmacol Sin 2013; 34:1381-5. [PMID: 24162508 DOI: 10.1038/aps.2013.150] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/16/2013] [Indexed: 12/27/2022] Open
Abstract
The intricate and complex interaction between different populations of neurons in the brain has imposed limits on our ability to gain detailed understanding of synaptic transmission and its integration when employing classical electrophysiological approaches. Indeed, electrical field stimulation delivered via traditional microelectrodes does not permit the targeted, precise and selective control of neuronal activity amongst a varied population of neurons and their inputs (eg, cholinergic, dopaminergic or glutamatergic neurons). Recently established optogenetic techniques overcome these limitations allowing precise control of the target neuron populations, which is essential for the elucidation of the neural substrates underlying complex animal behaviors. Indeed, by introducing light-activated channels (ie, microbial opsin genes) into specific neuronal populations, optogenetics enables non-invasive optical control of specific neurons with milliseconds precision. These approaches can readily be applied to freely behaving live animals. Recently there is increased interests in utilizing optogenetics tools to understand synaptic plasticity and learning/memory. Here, we summarize recent progress in applying optogenetics in in the study of synaptic plasticity.
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115
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Li D, Agulhon C, Schmidt E, Oheim M, Ropert N. New tools for investigating astrocyte-to-neuron communication. Front Cell Neurosci 2013; 7:193. [PMID: 24194698 PMCID: PMC3810613 DOI: 10.3389/fncel.2013.00193] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 10/07/2013] [Indexed: 12/24/2022] Open
Abstract
Gray matter protoplasmic astrocytes extend very thin processes and establish close contacts with synapses. It has been suggested that the release of neuroactive gliotransmitters at the tripartite synapse contributes to information processing. However, the concept of calcium (Ca2+)-dependent gliotransmitter release from astrocytes, and the release mechanisms are being debated. Studying astrocytes in their natural environment is challenging because: (i) astrocytes are electrically silent; (ii) astrocytes and neurons express an overlapping repertoire of transmembrane receptors; (iii) the size of astrocyte processes in contact with synapses are below the resolution of confocal and two-photon microscopes (iv) bulk-loading techniques using fluorescent Ca2+ indicators lack cellular specificity. In this review, we will discuss some limitations of conventional methodologies and highlight the interest of novel tools and approaches for studying gliotransmission. Genetically encoded Ca2+ indicators (GECIs), light-gated channels, and exogenous receptors are being developed to selectively read out and stimulate astrocyte activity. Our review discusses emerging perspectives on: (i) the complexity of astrocyte Ca2+ signaling revealed by GECIs; (ii) new pharmacogenetic and optogenetic approaches to activate specific Ca2+ signaling pathways in astrocytes; (iii) classical and new techniques to monitor vesicle fusion in cultured astrocytes; (iv) possible strategies to express specifically reporter genes in astrocytes.
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Affiliation(s)
- Dongdong Li
- Biophysics of Gliotransmitter Release Team, Laboratory of Neurophysiology and New Microscopies, INSERM U603, CNRS UMR 8154, University Paris Descartes Paris, France
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116
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Ono K, Suzuki H, Higa M, Tabata K, Sawada M. Glutamate release from astrocyte cell-line GL261 via alterations in the intracellular ion environment. J Neural Transm (Vienna) 2013; 121:245-57. [PMID: 24100416 DOI: 10.1007/s00702-013-1096-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 09/25/2013] [Indexed: 12/11/2022]
Abstract
Astrocytes modify and maintain neural activity and functions via gliotransmitter release such as, glutamate. They also change their properties and functions in response to alterations of ion environment resulting from neurotransmission; however, the direct evidence for whether intracellular ion alteration in astrocytes triggers gliotransmitter release is not indicated. Recent studies have reported that channelrhodopsin-2 (ChR2) is useful for alteration of intracellular ion environment in several types of cells with blue light exposure. Here, we show that ChR2-expressing GL261 (GLChR2) cells, clonal astrocytes, change their properties by photo-activation. Increased intracellular sodium and calcium ion concentrations and an altered membrane potential were observed in GLChR2 cells with blue light exposure. Alterations in the intracellular ion environment caused intracellular acidification and the inhibition of proliferation. In addition, it triggered glutamate release from GLChR2 cells. Glutamate from GLChR2 cells acted on N18 cells, clonal neuronal cells, as both a transmitter and neurotoxin depending on photo-activation. Our results show that the properties of ChR2-expressing astrocytes can be controlled by blue light exposure, and cation influx through photo-activated ChR2 might trigger functional cation influx via endogenous channels and result in the increase of glutamate release. Further, our results suggest that ChR2-expressing glial cells could become a useful tool in understanding the roles of glial cell activation and neural communication in the regulation of brain functions.
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Affiliation(s)
- Kenji Ono
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan
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117
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Buffo A, Rossi F. Origin, lineage and function of cerebellar glia. Prog Neurobiol 2013; 109:42-63. [PMID: 23981535 DOI: 10.1016/j.pneurobio.2013.08.001] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/06/2013] [Accepted: 08/07/2013] [Indexed: 11/16/2022]
Abstract
The glial cells of the cerebellum, and particularly astrocytes and oligodendrocytes, are characterized by a remarkable phenotypic variety, in which highly peculiar morphological features are associated with specific functional features, unique among the glial cells of the entire CNS. Here, we provide a critical report about the present knowledge of the development of cerebellar glia, including lineage relationships between cerebellar neurons, astrocytes and oligodendrocytes, the origins and the genesis of the repertoire of glial types, and the processes underlying their acquisition of mature morphological and functional traits. In parallel, we describe and discuss some fundamental roles played by specific categories of glial cells during cerebellar development. In particular, we propose that Bergmann glia exerts a crucial scaffolding activity that, together with the organizing function of Purkinje cells, is necessary to achieve the normal pattern of foliation and layering of the cerebellar cortex. Moreover, we discuss some of the functional tasks of cerebellar astrocytes and oligodendrocytes that are distinctive of cerebellar glia throughout the CNS. Notably, we report about the regulation of synaptic signalling in the molecular and granular layer mediated by Bergmann glia and parenchymal astrocytes, and the functional interaction between oligodendrocyte precursor cells and neurons. On the whole, this review provides an extensive overview of the available literature and some novel insights about the origin and differentiation of the variety of cerebellar glial cells and their function in the developing and mature cerebellum.
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Affiliation(s)
- Annalisa Buffo
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, Corso Raffaello, 30, 10125 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, Neuroscience Institute of Turin, University of Turin, Regione Gonzole 10, 10043 Orbassano, Turin, Italy.
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118
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Lammel S, Tye KM, Warden MR. Progress in understanding mood disorders: optogenetic dissection of neural circuits. GENES BRAIN AND BEHAVIOR 2013; 13:38-51. [PMID: 23682971 DOI: 10.1111/gbb.12049] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/22/2013] [Accepted: 05/14/2013] [Indexed: 12/13/2022]
Abstract
Major depression is characterized by a cluster of symptoms that includes hopelessness, low mood, feelings of worthlessness and inability to experience pleasure. The lifetime prevalence of major depression approaches 20%, yet current treatments are often inadequate both because of associated side effects and because they are ineffective for many people. In basic research, animal models are often used to study depression. Typically, experimental animals are exposed to acute or chronic stress to generate a variety of depression-like symptoms. Despite its clinical importance, very little is known about the cellular and neural circuits that mediate these symptoms. Recent advances in circuit-targeted approaches have provided new opportunities to study the neuropathology of mood disorders such as depression and anxiety. We review recent progress and highlight some studies that have begun tracing a functional neuronal circuit diagram that may prove essential in establishing novel treatment strategies in mood disorders. First, we shed light on the complexity of mesocorticolimbic dopamine (DA) responses to stress by discussing two recent studies reporting that optogenetic activation of midbrain DA neurons can induce or reverse depression-related behaviors. Second, we describe the role of the lateral habenula circuitry in the pathophysiology of depression. Finally, we discuss how the prefrontal cortex controls limbic and neuromodulatory circuits in mood disorders.
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Affiliation(s)
- S Lammel
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
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119
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Hiraoka Y, Komine O, Nagaoka M, Bai N, Hozumi K, Tanaka K. Delta-like 1 regulates Bergmann glial monolayer formation during cerebellar development. Mol Brain 2013. [PMID: 23688253 DOI: 10.1186/1756‐6606‐6‐25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Bergmann glia (BG) are unipolar cerebellar astrocytes. The somata of mature BG reside in the Purkinje cell layer and extend radially arranged processes to the pial surface. BG have multiple branched processes, which enwrap the synapses of Purkinje cell dendrites. They migrate from the ventricular zone and align next to the Purkinje cell layer during development. Previously, we reported that Notch1, Notch2, and RBPj genes in the BG play crucial roles in the monolayer formation and morphogenesis of BG. However, it remains to be determined which ligand activates Nocth1 and Notch 2 on BG. Delta-like 1 (Dll1) is a major ligand of Notch receptors that is expressed in the developing cerebellum. RESULTS In this study, we used human glial fibrillary acidic protein (hGFAP) promoter-driven Cre-mediated recombination to delete Dll1 in BG. Dll1-conditional mutant mice showed disorganization of Bergmann fibers, ectopic localization of BG in the molecular layer and a reduction in the number of BG. CONCLUSION These results suggest that Dll1 is required for the formation of the BG layer and its morphological maturation, apparently through a Notch1/2-RBPj dependent signaling pathway.
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Affiliation(s)
- Yuichi Hiraoka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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120
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Hiraoka Y, Komine O, Nagaoka M, Bai N, Hozumi K, Tanaka K. Delta-like 1 regulates Bergmann glial monolayer formation during cerebellar development. Mol Brain 2013; 6:25. [PMID: 23688253 PMCID: PMC3724498 DOI: 10.1186/1756-6606-6-25] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 05/19/2013] [Indexed: 11/25/2022] Open
Abstract
Background Bergmann glia (BG) are unipolar cerebellar astrocytes. The somata of mature BG reside in the Purkinje cell layer and extend radially arranged processes to the pial surface. BG have multiple branched processes, which enwrap the synapses of Purkinje cell dendrites. They migrate from the ventricular zone and align next to the Purkinje cell layer during development. Previously, we reported that Notch1, Notch2, and RBPj genes in the BG play crucial roles in the monolayer formation and morphogenesis of BG. However, it remains to be determined which ligand activates Nocth1 and Notch 2 on BG. Delta-like 1 (Dll1) is a major ligand of Notch receptors that is expressed in the developing cerebellum. Results In this study, we used human glial fibrillary acidic protein (hGFAP) promoter-driven Cre-mediated recombination to delete Dll1 in BG. Dll1-conditional mutant mice showed disorganization of Bergmann fibers, ectopic localization of BG in the molecular layer and a reduction in the number of BG. Conclusion These results suggest that Dll1 is required for the formation of the BG layer and its morphological maturation, apparently through a Notch1/2-RBPj dependent signaling pathway.
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Affiliation(s)
- Yuichi Hiraoka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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121
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Tsubota T, Ohashi Y, Tamura K. Optogenetics in the cerebellum: Purkinje cell-specific approaches for understanding local cerebellar functions. Behav Brain Res 2013; 255:26-34. [PMID: 23623886 DOI: 10.1016/j.bbr.2013.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 04/14/2013] [Accepted: 04/15/2013] [Indexed: 11/30/2022]
Abstract
The cerebellum consists of the cerebellar cortex and the cerebellar nuclei. Although the basic neuronal circuitry of the cerebellar cortex is uniform everywhere, anatomical data demonstrate that the input and output relationships of the cortex are spatially segregated between different cortical areas, which suggests that there are functional distinctions between these different areas. Perturbation of cerebellar cortical functions in a spatially restricted fashion is thus essential for investigating the distinctions among different cortical areas. In the cerebellar cortex, Purkinje cells are the sole output neurons that send information to downstream cerebellar and vestibular nuclei. Therefore, selective manipulation of Purkinje cell activities, without disturbing other neuronal types and passing fibers within the cortex, is a direct approach to spatially restrict the effects of perturbations. Although this type of approach has for many years been technically difficult, recent advances in optogenetics now enable selective activation or inhibition of Purkinje cell activities, with high temporal resolution. Here we discuss the effectiveness of using Purkinje cell-specific optogenetic approaches to elucidate the functions of local cerebellar cortex regions. We also discuss what improvements to current methods are necessary for future investigations of cerebellar functions to provide further advances.
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Affiliation(s)
- Tadashi Tsubota
- Department of Physiology, The University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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122
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Yawo H, Asano T, Sakai S, Ishizuka T. Optogenetic manipulation of neural and non-neural functions. Dev Growth Differ 2013; 55:474-90. [PMID: 23550617 DOI: 10.1111/dgd.12053] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 01/22/2023]
Abstract
Optogenetic manipulation of the neuronal activity enables one to analyze the neuronal network both in vivo and in vitro with precise spatio-temporal resolution. Channelrhodopsins (ChRs) are light-sensitive cation channels that depolarize the cell membrane, whereas halorhodopsins and archaerhodopsins are light-sensitive Cl(-) and H(+) transporters, respectively, that hyperpolarize it when exogenously expressed. The cause-effect relationship between a neuron and its function in the brain is thus bi-directionally investigated with evidence of necessity and sufficiency. In this review we discuss the potential of optogenetics with a focus on three major requirements for its application: (i) selection of the light-sensitive proteins optimal for optogenetic investigation, (ii) targeted expression of these selected proteins in a specific group of neurons, and (iii) targeted irradiation with high spatiotemporal resolution. We also discuss recent progress in the application of optogenetics to studies of non-neural cells such as glial cells, cardiac and skeletal myocytes. In combination with stem cell technology, optogenetics may be key to successful research using embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) derived from human patients through optical regulation of differentiation-maturation, through optical manipulation of tissue transplants and, furthermore, through facilitating survival and integration of transplants.
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Affiliation(s)
- Hiromu Yawo
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
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123
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Krencik R, Ullian EM. A cellular star atlas: using astrocytes from human pluripotent stem cells for disease studies. Front Cell Neurosci 2013; 7:25. [PMID: 23503583 PMCID: PMC3596764 DOI: 10.3389/fncel.2013.00025] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 02/28/2013] [Indexed: 11/13/2022] Open
Abstract
What roles do astrocytes play in human disease?This question remains unanswered for nearly every human neurological disorder. Yet, because of their abundance and complexity astrocytes can impact neurological function in many ways. The differentiation of human pluripotent stem cells (hPSCs) into neuronal and glial subtypes, including astrocytes, is becoming routine, thus their use as tools for modeling neurodevelopment and disease will provide one important approach to answer this question. When designing experiments, careful consideration must be given to choosing paradigms for differentiation, maturation, and functional analysis of these temporally asynchronous cellular populations in culture. In the case of astrocytes, they display heterogeneous characteristics depending upon species of origin, brain region, developmental stage, environmental factors, and disease states, all of which may render experimental results highly variable. In this review, challenges and future directions are discussed for using hPSC-derived astroglial progenitors and mature astrocytes for neurodevelopmental studies with a focus on exploring human astrocyte effects upon neuronal function. As new technologies emerge to measure the functions of astrocytes in vitro and in vivo, there is also a need for a standardized source of human astrocytes that are most relevant to the diseases of interest.
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Affiliation(s)
- Robert Krencik
- Departments of Ophthalmology and Physiology, Neuroscience Program, University of California San Francisco, CA, USA
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124
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Ting JT, Feng G. Development of transgenic animals for optogenetic manipulation of mammalian nervous system function: progress and prospects for behavioral neuroscience. Behav Brain Res 2013; 255:3-18. [PMID: 23473879 DOI: 10.1016/j.bbr.2013.02.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 02/14/2013] [Accepted: 02/23/2013] [Indexed: 12/21/2022]
Abstract
Here we review the rapidly growing toolbox of transgenic mice and rats that exhibit functional expression of engineered opsins for neuronal activation and silencing with light. Collectively, these transgenic animals are enabling neuroscientists to access and manipulate the many diverse cell types in the mammalian nervous system in order to probe synaptic and circuitry connectivity, function, and dysfunction. The availability of transgenic lines affords important advantages such as stable and heritable transgene expression patterns across experimental cohorts. As such, the use of transgenic lines precludes the need for other costly and labor-intensive procedures to achieve functional transgene expression in each individual experimental animal. This represents an important consideration when large cohorts of experimental animals are desirable as in many common behavioral assays. We describe the diverse strategies that have been implemented for developing transgenic mouse and rat lines and highlight recent advances that have led to dramatic improvements in achieving functional transgene expression of engineered opsins. Furthermore, we discuss considerations and caveats associated with implementing recently developed transgenic lines for optogenetics-based experimentation. Lastly, we propose strategies that can be implemented to develop and refine the next generation of genetically modified animals for behaviorally-focused optogenetics-based applications.
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Affiliation(s)
- Jonathan T Ting
- McGovern Institute for Brain Research and Department of Brain & Cognitive Sciences, MIT, Cambridge, MA 02139, USA.
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