1
|
Shu WC, Jackson MB. Intrinsic and Synaptic Contributions to Repetitive Spiking in Dentate Granule Cells. J Neurosci 2024; 44:e0716232024. [PMID: 38503495 PMCID: PMC11063872 DOI: 10.1523/jneurosci.0716-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 03/03/2024] [Accepted: 03/05/2024] [Indexed: 03/21/2024] Open
Abstract
Repetitive firing of granule cells (GCs) in the dentate gyrus (DG) facilitates synaptic transmission to the CA3 region. This facilitation can gate and amplify the flow of information through the hippocampus. High-frequency bursts in the DG are linked to behavior and plasticity, but GCs do not readily burst. Under normal conditions, a single shock to the perforant path in a hippocampal slice typically drives a GC to fire a single spike, and only occasionally more than one spike is seen. Repetitive spiking in GCs is not robust, and the mechanisms are poorly understood. Here, we used a hybrid genetically encoded voltage sensor to image voltage changes evoked by cortical inputs in many mature GCs simultaneously in hippocampal slices from male and female mice. This enabled us to study relatively infrequent double and triple spikes. We found GCs are relatively homogeneous and their double spiking behavior is cell autonomous. Blockade of GABA type A receptors increased multiple spikes and prolonged the interspike interval, indicating inhibitory interneurons limit repetitive spiking and set the time window for successive spikes. Inhibiting synaptic glutamate release showed that recurrent excitation mediated by hilar mossy cells contributes to, but is not necessary for, multiple spiking. Blockade of T-type Ca2+ channels did not reduce multiple spiking but prolonged interspike intervals. Imaging voltage changes in different GC compartments revealed that second spikes can be initiated in either dendrites or somata. Thus, pharmacological and biophysical experiments reveal roles for both synaptic circuitry and intrinsic excitability in GC repetitive spiking.
Collapse
Affiliation(s)
- Wen-Chi Shu
- Department of Neuroscience and Biophysics Program, University of Wisconsin-Madison, Wisconsin 53705
| | - Meyer B Jackson
- Department of Neuroscience and Biophysics Program, University of Wisconsin-Madison, Wisconsin 53705
| |
Collapse
|
2
|
Vandael D, Jonas P. Structure, biophysics, and circuit function of a "giant" cortical presynaptic terminal. Science 2024; 383:eadg6757. [PMID: 38452088 DOI: 10.1126/science.adg6757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 01/19/2024] [Indexed: 03/09/2024]
Abstract
The hippocampal mossy fiber synapse, formed between axons of dentate gyrus granule cells and dendrites of CA3 pyramidal neurons, is a key synapse in the trisynaptic circuitry of the hippocampus. Because of its comparatively large size, this synapse is accessible to direct presynaptic recording, allowing a rigorous investigation of the biophysical mechanisms of synaptic transmission and plasticity. Furthermore, because of its placement in the very center of the hippocampal memory circuit, this synapse seems to be critically involved in several higher network functions, such as learning, memory, pattern separation, and pattern completion. Recent work based on new technologies in both nanoanatomy and nanophysiology, including presynaptic patch-clamp recording, paired recording, super-resolution light microscopy, and freeze-fracture and "flash-and-freeze" electron microscopy, has provided new insights into the structure, biophysics, and network function of this intriguing synapse. This brings us one step closer to answering a fundamental question in neuroscience: how basic synaptic properties shape higher network computations.
Collapse
Affiliation(s)
- David Vandael
- Institute of Science and Technology Austria (ISTA), A-3400 Klosterneuburg, Austria
| | - Peter Jonas
- Institute of Science and Technology Austria (ISTA), A-3400 Klosterneuburg, Austria
| |
Collapse
|
3
|
Pelkey KA, Vargish GA, Pellegrini LV, Calvigioni D, Chapeton J, Yuan X, Hunt S, Cummins AC, Eldridge MAG, Pickel J, Chittajallu R, Averbeck BB, Tóth K, Zaghloul K, McBain CJ. Evolutionary conservation of hippocampal mossy fiber synapse properties. Neuron 2023; 111:3802-3818.e5. [PMID: 37776852 PMCID: PMC10841147 DOI: 10.1016/j.neuron.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/03/2023] [Accepted: 09/06/2023] [Indexed: 10/02/2023]
Abstract
Various specialized structural/functional properties are considered essential for contextual memory encoding by hippocampal mossy fiber (MF) synapses. Although investigated to exquisite detail in model organisms, synapses, including MFs, have undergone minimal functional interrogation in humans. To determine the translational relevance of rodent findings, we evaluated MF properties within human tissue resected to treat epilepsy. Human MFs exhibit remarkably similar hallmark features to rodents, including AMPA receptor-dominated synapses with small contributions from NMDA and kainate receptors, large dynamic range with strong frequency facilitation, NMDA receptor-independent presynaptic long-term potentiation, and strong cyclic AMP (cAMP) sensitivity of release. Array tomography confirmed the evolutionary conservation of MF ultrastructure. The astonishing congruence of rodent and human MF core features argues that the basic MF properties delineated in animal models remain critical to human MF function. Finally, a selective deficit in GABAergic inhibitory tone onto human MF postsynaptic targets suggests that unrestrained detonator excitatory drive contributes to epileptic circuit hyperexcitability.
Collapse
Affiliation(s)
- Kenneth A Pelkey
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Geoffrey A Vargish
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Leonardo V Pellegrini
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Daniela Calvigioni
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio Chapeton
- National Institute of Neurological Disorders and Stroke Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaoqing Yuan
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Steven Hunt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alex C Cummins
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mark A G Eldridge
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - James Pickel
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ramesh Chittajallu
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bruno B Averbeck
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Katalin Tóth
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Kareem Zaghloul
- National Institute of Neurological Disorders and Stroke Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chris J McBain
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
4
|
Ma J, Hu Z, Yue H, Luo Y, Wang C, Wu X, Gu Y, Wang L. GRM2 Regulates Functional Integration of Adult-Born DGCs by Paradoxically Modulating MEK/ERK1/2 Pathway. J Neurosci 2023; 43:2822-2836. [PMID: 36878727 PMCID: PMC10124958 DOI: 10.1523/jneurosci.1886-22.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 02/01/2023] [Accepted: 02/19/2023] [Indexed: 03/08/2023] Open
Abstract
Metabotropic glutamate receptor 2 (GRM2) is highly expressed in hippocampal dentate granule cells (DGCs), regulating synaptic transmission and hippocampal functions. Newborn DGCs are continuously generated throughout life and express GRM2 when they are mature. However, it remained unclear whether and how GRM2 regulates the development and integration of these newborn neurons. We discovered that the expression of GRM2 in adult-born DGCs increased with neuronal development in mice of both sexes. Lack of GRM2 caused developmental defects of DGCs and impaired hippocampus-dependent cognitive functions. Intriguingly, our data showed that knockdown of Grm2 resulted in decreased b/c-Raf kinases and paradoxically led to an excessive activation of MEK/ERK1/2 pathway. Inhibition of MEK ameliorated the developmental defects caused by Grm2 knockdown. Together, our results indicate that GRM2 is necessary for the development and functional integration of newborn DGCs in the adult hippocampus through regulating the phosphorylation and activation state of MEK/ERK1/2 pathway.SIGNIFICANCE STATEMENT Metabotropic glutamate receptor 2 (GRM2) is highly expressed in mature dentate granule cells (DGCs) in the hippocampus. It remains unclear whether GRM2 is required for the development and integration of adult-born DGCs. We provided in vivo and in vitro evidence to show that GRM2 regulates the development of adult-born DGCs and their integration into existing hippocampal circuits. Lack of GRM2 in a cohort of newborn DGCs impaired object-to-location memory in mice. Moreover, we revealed that GRM2 knockdown paradoxically upregulated MEK/ERK1/2 pathway by suppressing b/c-Raf in developing neurons, which is likely a common mechanism underlying the regulation of the development of neurons expressing GRM2. Thus, Raf/MEK/ERK1/2 pathway could be a potential target for brain diseases related to GRM2 abnormality.
Collapse
Affiliation(s)
- Jiao Ma
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, 310027 Hangzhou, People's Republic of China
- Center of Stem Cell and Regenerative Medicine, and Department of Neurology of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, 310058 Hangzhou, People's Republic of China
| | - Zhechun Hu
- School of Brain Science and Brain Medicine, Zhejiang University, 310058 Hangzhou, People's Republic of China
| | - Huimin Yue
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, 310027 Hangzhou, People's Republic of China
- School of Brain Science and Brain Medicine, Zhejiang University, 310058 Hangzhou, People's Republic of China
| | - Yujian Luo
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, 310027 Hangzhou, People's Republic of China
- School of Brain Science and Brain Medicine, Zhejiang University, 310058 Hangzhou, People's Republic of China
| | - Chao Wang
- School of Brain Science and Brain Medicine, Zhejiang University, 310058 Hangzhou, People's Republic of China
| | - Xuan Wu
- Center of Stem Cell and Regenerative Medicine, and Department of Neurology of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, 310058 Hangzhou, People's Republic of China
| | - Yan Gu
- Center of Stem Cell and Regenerative Medicine, and Department of Neurology of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, 310058 Hangzhou, People's Republic of China
- MOE Frontier Science Center for Brain Science and Brain-Machine Integration, Zhejiang University, 310058 Hangzhou, People's Republic of China
| | - Lang Wang
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, 310027 Hangzhou, People's Republic of China
- School of Brain Science and Brain Medicine, Zhejiang University, 310058 Hangzhou, People's Republic of China
| |
Collapse
|
5
|
Márquez LA, Griego E, López Rubalcava C, Galván EJ. NMDA receptor activity during postnatal development determines intrinsic excitability and mossy fiber long-term potentiation of CA3 pyramidal cells. Hippocampus 2023. [PMID: 36938755 DOI: 10.1002/hipo.23524] [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: 12/02/2022] [Revised: 01/30/2023] [Accepted: 02/23/2023] [Indexed: 03/21/2023]
Abstract
Experimental manipulations that interfere with the functional expression of N-methyl-D-aspartate receptors (NMDARs) during prenatal neurodevelopment or critical periods of postnatal development are models that mimic behavioral and neurophysiological abnormalities of schizophrenia. Blockade of NMDARs with MK-801 during early postnatal development alters glutamate release and impairs the induction of NMDAR-dependent long-term plasticity at the CA1 area of the hippocampus. However, it remains unknown if other forms of hippocampal plasticity, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated short- and long-term potentiation, are compromised in response to neonatal treatment with MK-801. Consistent with this tenet, short- and long-term potentiation between dentate gyrus axons, the mossy fibers (MF), onto CA3 pyramidal cells (CA3 PCs) are mediated by AMPARs. By combining whole-cell patch clamp and extracellular recordings, we have demonstrated that transient blockade of NMDARs during early postnatal development induces a series of pre- and postsynaptic modifications at the MF-CA3 synapse. We found reduced glutamate release from the mossy boutons, increased paired-pulse ratio, and reduced AMPAR-mediated MF LTP levels. At the postsynaptic level, we found an altered NMDA/AMPA ratio and dysregulation of several potassium conductances that increased the excitability of CA3 PCs. In addition, MK-801-treated animals exhibited impaired spatial memory retrieval in the Barnes maze task. Our data demonstrate that transient hypofunction of NMDARs impacts NMDAR-independent forms of synaptic plasticity of the hippocampus.
Collapse
Affiliation(s)
- Luis A Márquez
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | - Ernesto Griego
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | | | - Emilio J Galván
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico.,Centro de Investigaciones sobre el Envejecimiento, CIE-Cinvestav, Ciudad de México, Mexico
| |
Collapse
|
6
|
Temml V, Kollár J, Schönleitner T, Höll A, Schuster D, Kutil Z. Combination of In Silico and In Vitro Screening to Identify Novel Glutamate Carboxypeptidase II Inhibitors. J Chem Inf Model 2023; 63:1249-1259. [PMID: 36799916 PMCID: PMC9976286 DOI: 10.1021/acs.jcim.2c01269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Indexed: 02/18/2023]
Abstract
Glutamate carboxypeptidase II (GCPII) is a metalloprotease implicated in neurological diseases and prostate oncology. While several classes of potent GCPII-specific inhibitors exist, the development of novel active scaffolds with different pharmacological profiles remains a challenge. Virtual screening followed by in vitro testing is an effective means for the discovery of novel active compounds. Structure- and ligand-based pharmacophore models were created based on a dataset of known GCPII-selective ligands. These models were used in a virtual screening of the SPECS compound library (∼209.000 compounds). Fifty top-scoring virtual hits were further experimentally tested for their ability to inhibit GCPII enzymatic activity in vitro. Six hits were found to have moderate to high inhibitory potency with the best virtual hit, a modified xanthene, inhibiting GCPII with an IC50 value of 353 ± 24 nM. The identification of this novel inhibitory scaffold illustrates the applicability of pharmacophore-based modeling for the discovery of GCPII-specific inhibitors.
Collapse
Affiliation(s)
- Veronika Temml
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Jakub Kollár
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Theresa Schönleitner
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Anna Höll
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Daniela Schuster
- Department
of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Zsófia Kutil
- Laboratory
of Structural Biology, Institute of Biotechnology
of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252
50 Vestec, Czech
Republic
| |
Collapse
|
7
|
Fukaya R, Hirai H, Sakamoto H, Hashimotodani Y, Hirose K, Sakaba T. Increased vesicle fusion competence underlies long-term potentiation at hippocampal mossy fiber synapses. SCIENCE ADVANCES 2023; 9:eadd3616. [PMID: 36812326 PMCID: PMC9946361 DOI: 10.1126/sciadv.add3616] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Presynaptic long-term potentiation (LTP) is thought to play an important role in learning and memory. However, the underlying mechanism remains elusive because of the difficulty of direct recording during LTP. Hippocampal mossy fiber synapses exhibit pronounced LTP of transmitter release after tetanic stimulation and have been used as a model of presynaptic LTP. Here, we induced LTP by optogenetic tools and applied direct presynaptic patch-clamp recordings. The action potential waveform and evoked presynaptic Ca2+ currents remained unchanged after LTP induction. Membrane capacitance measurements suggested higher release probability of synaptic vesicles without changing the number of release-ready vesicles after LTP induction. Synaptic vesicle replenishment was also enhanced. Furthermore, stimulated emission depletion microscopy suggested an increase in the numbers of Munc13-1 and RIM1 molecules within active zones. We propose that dynamic changes in the active zone components may be relevant for the increased fusion competence and synaptic vesicle replenishment during LTP.
Collapse
Affiliation(s)
- Ryota Fukaya
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
- Institute of Biology/Genetics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Himawari Hirai
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Hirokazu Sakamoto
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuki Hashimotodani
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Kenzo Hirose
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| |
Collapse
|
8
|
Devine MJ, Szulc BR, Howden JH, López-Doménech G, Ruiz A, Kittler JT. Mitochondrial Ca2+ uniporter haploinsufficiency enhances long-term potentiation at hippocampal mossy fibre synapses. J Cell Sci 2022; 135:jcs259823. [PMID: 36274588 PMCID: PMC10563808 DOI: 10.1242/jcs.259823] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 10/18/2022] [Indexed: 11/20/2022] Open
Abstract
Long-term changes in synaptic strength form the basis of learning and memory. These changes rely upon energy-demanding mechanisms, which are regulated by local Ca2+ signalling. Mitochondria are optimised for providing energy and buffering Ca2+. However, our understanding of the role of mitochondria in regulating synaptic plasticity is incomplete. Here, we have used optical and electrophysiological techniques in cultured hippocampal neurons and ex vivo hippocampal slices from mice with haploinsufficiency of the mitochondrial Ca2+ uniporter (MCU+/-) to address whether reducing mitochondrial Ca2+ uptake alters synaptic transmission and plasticity. We found that cultured MCU+/- hippocampal neurons have impaired Ca2+ clearance, and consequently enhanced synaptic vesicle fusion at presynapses occupied by mitochondria. Furthermore, long-term potentiation (LTP) at mossy fibre (MF) synapses, a process which is dependent on presynaptic Ca2+ accumulation, is enhanced in MCU+/- slices. Our results reveal a previously unrecognised role for mitochondria in regulating presynaptic plasticity of a major excitatory pathway involved in learning and memory.
Collapse
Affiliation(s)
- Michael J. Devine
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Blanka R. Szulc
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jack H. Howden
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Guillermo López-Doménech
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Arnaud Ruiz
- Department of Pharmacology, School of Pharmacy, University College London, Brunswick Square, London WC1N 1AX, UK
| | - Josef T. Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| |
Collapse
|
9
|
Zhao C, Li C, Zhao B, Liu Y. Expression of group II and III mGluRs in the carotid body and its role in the carotid chemoreceptor response to acute hypoxia. Front Physiol 2022; 13:1008073. [PMID: 36213225 PMCID: PMC9536148 DOI: 10.3389/fphys.2022.1008073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
The carotid body (CB) contributes significantly to oxygen sensing. It is unclear, however, whether glutamatergic signaling is involved in the CB response to hypoxia. Previously, we reported that ionotropic glutamate receptors (iGluRs) and multiple glutamate transporters are present in the rat CB. Except for iGluRs, glutamate receptors also include metabotropic glutamate receptors (mGluRs), which are divided into the following groups: Group I (mGluR1/5); group II (mGluR2/3); group III (mGluR4/6/7/8). We have studied the expression of group I mGluRs in the rat CB and its physiological function response to acute hypoxia. To further elucidate the states of mGluRs in the CB, this study’s aim was to investigate the expression of group II and III mGluRs and the response of rat CB to acute hypoxia. We used reverse transcription-polymerase chain reaction (RT-PCR) to observed mRNA expression of GRM2/3/4/6/7/8 subunits by using immunostaining to show the distribution of mGluR2 and mGluR8. The results revealed that the GRM2/3/4/6/7/8 mRNAs were expressed in both rat and human CB. Immunostaining showed that mGluR2 was localized in the type I cells and mGluR8 was localized in type I and type II cells in the rat CB. Moreover, the response of CB to acute hypoxia in rats was recorded by in vitro carotid sinus nerve (CSN) discharge. Perfusion of group II mGluRs agonist or group III mGluRs agonist (LY379268 or L-SOP) was applied to examine the effect of group II and III mGluRs on rat CB response to acute hypoxia. We found that LY379268 and L-SOP inhibited hypoxia-induced enhancement of CSN activity. Based on the above findings, group II and III mGluRs appear to play an inhibitory role in the carotid chemoreceptor response to acute hypoxia.
Collapse
Affiliation(s)
- Chenlu Zhao
- Henan Key Laboratory of Neurorestoratology, Life Science Research Center, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China
| | - Chaohong Li
- Henan Key Laboratory of Neurorestoratology, Life Science Research Center, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China
| | - Baosheng Zhao
- Department of Thoracic Surgery, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China
| | - Yuzhen Liu
- Henan Key Laboratory of Neurorestoratology, Life Science Research Center, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China
- Department of Thoracic Surgery, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China
- *Correspondence: Yuzhen Liu,
| |
Collapse
|
10
|
Pak S, Choi G, Roy J, Poon CH, Lee J, Cho D, Lee M, Lim LW, Bao S, Yang S, Yang S. Altered synaptic plasticity of the longitudinal dentate gyrus network in noise-induced anxiety. iScience 2022; 25:104364. [PMID: 35620435 PMCID: PMC9127171 DOI: 10.1016/j.isci.2022.104364] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/31/2022] [Accepted: 05/03/2022] [Indexed: 12/20/2022] Open
Abstract
Anxiety is characteristic comorbidity of noise-induced hearing loss (NIHL), which causes physiological changes within the dentate gyrus (DG), a subfield of the hippocampus that modulates anxiety. However, which DG circuit underlies hearing loss-induced anxiety remains unknown. We utilize an NIHL mouse model to investigate short- and long-term synaptic plasticity in DG networks. The recently discovered longitudinal DG-DG network is a collateral of DG neurons synaptically connected with neighboring DG neurons and displays robust synaptic efficacy and plasticity. Furthermore, animals with NIHL demonstrate increased anxiety-like behaviors similar to a response to chronic restraint stress. These behaviors are concurrent with enhanced synaptic responsiveness and suppressed short- and long-term synaptic plasticity in the longitudinal DG-DG network but not in the transverse DG-CA3 connection. These findings suggest that DG-related anxiety is typified by synaptic alteration in the longitudinal DG-DG network. Traumatic noise-induced hearing loss enhances anxiety-like behaviors The longitudinal DG-DG network displays robust synaptic efficacy and plasticity Abnormal anxiety is associated with synaptic alterations of the DG-DG network DG-related brain disorders might stem from dysfunctional DG-DG networks
Collapse
|
11
|
Tanaka M, Sakaba T, Miki T. Quantal analysis estimates docking site occupancy determining short-term depression at hippocampal glutamatergic synapses. J Physiol 2021; 599:5301-5327. [PMID: 34705277 DOI: 10.1113/jp282235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/20/2021] [Indexed: 12/23/2022] Open
Abstract
Before fusion, synaptic vesicles (SVs) pause at discrete release/docking sites. During repetitive stimulation, the probability of site occupancy changes following SV fusion and replenishment. The occupancy probability is considered to be one of the crucial determinants of synaptic strength, but it is difficult to estimate separately because it usually blends with other synaptic parameters. Thus, the contribution of site occupancy to synaptic function, particularly to synaptic depression, remains elusive. Here, we directly estimated the occupancy probability at the hippocampal mossy fibre-CA3 interneuron synapse showing synaptic depression, using statistics of counts of vesicular events detected by deconvolution. We found that this synapse had a particularly high occupancy (∼0.85) with a high release probability of a docked SV (∼0.8) under 3 mm external calcium conditions. Analyses of quantal amplitudes and SV counts indicated that quantal size reduction decreased the amplitudes of all responses in a train to a similar degree, whereas release/docking site number was unchanged during trains, suggesting that quantal size and release/docking site number had little influence on the extent of synaptic depression. Model simulations revealed that the initial occupancy with high release probability and slow replenishment determined the time course of synaptic depression. Consistently, decreasing external calcium concentration reduced both the occupancy and release probability, and the reductions in turn produced less depression. Based on these results, we suggest that the occupancy probability is a crucial determinant of short-term synaptic depression at glutamatergic synapses in the hippocampus. KEY POINTS: The occupancy probability of a release/docking site by a synaptic vesicle at presynaptic terminals is considered to be one of the crucial determinants of synaptic strength, but it is difficult to estimate separately from other synaptic parameters. Here, we directly estimate the occupancy probability at the hippocampal mossy fibre-interneuron synapse using statistics of vesicular events detected by deconvolution. We show that the synapses have particularly high occupancy (0.85) with high release probability (0.8) under high external calcium concentration ([Ca2+ ]o ) conditions, and that both parameter values change with [Ca2+ ]o , shaping synaptic depression. Analyses of the quantal amplitudes and synaptic vesicle counts suggest that quantal sizes and release/docking site number have little influence on the extent of synaptic depression. The results suggest that the occupancy probability is a crucial determinant of short-term synaptic depression at glutamatergic synapses in the hippocampus.
Collapse
Affiliation(s)
- Mamoru Tanaka
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Takafumi Miki
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan.,Organization for Research Initiatives and Development, Doshisha University, Kyoto, Japan
| |
Collapse
|
12
|
Brandalise F, Carta S, Leone R, Helmchen F, Holtmaat A, Gerber U. Dendritic Branch-constrained N-Methyl-d-Aspartate Receptor-mediated Spikes Drive Synaptic Plasticity in Hippocampal CA3 Pyramidal Cells. Neuroscience 2021; 489:57-68. [PMID: 34634424 DOI: 10.1016/j.neuroscience.2021.10.002] [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: 03/18/2021] [Revised: 09/27/2021] [Accepted: 10/03/2021] [Indexed: 10/20/2022]
Abstract
N-methyl-d-aspartate receptor-mediated ( spikes can be causally linked to the induction of synaptic long-term potentiation (LTP) in hippocampal and cortical pyramidal cells. However, it is unclear if they regulate plasticity at a local or global scale in the dendritic tree. Here, we used dendritic patch-clamp recordings and calcium imaging to investigate the integrative properties of single dendrites of hippocampal CA3 cells. We show that local hyperpolarization of a single dendritic segment prevents NMDA spikes, their associated calcium transients, as well as LTP in a branch-specific manner. This result provides direct, causal evidence that the single dendritic branch can operate as a functional unit in regulating CA3 pyramidal cell plasticity.
Collapse
Affiliation(s)
- Federico Brandalise
- Department of Basic Neurosciences and the Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva, 1211 Geneva, Switzerland; Former affiliation(b).
| | - Stefano Carta
- Brain Research Institute and Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Roberta Leone
- Department of Basic Neurosciences and the Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva, 1211 Geneva, Switzerland
| | - Fritjof Helmchen
- Brain Research Institute and Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
| | - Anthony Holtmaat
- Department of Basic Neurosciences and the Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva, 1211 Geneva, Switzerland
| | | |
Collapse
|
13
|
Prince LY, Bacon T, Humphries R, Tsaneva-Atanasova K, Clopath C, Mellor JR. Separable actions of acetylcholine and noradrenaline on neuronal ensemble formation in hippocampal CA3 circuits. PLoS Comput Biol 2021; 17:e1009435. [PMID: 34597293 PMCID: PMC8513881 DOI: 10.1371/journal.pcbi.1009435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 10/13/2021] [Accepted: 09/08/2021] [Indexed: 11/19/2022] Open
Abstract
In the hippocampus, episodic memories are thought to be encoded by the formation of ensembles of synaptically coupled CA3 pyramidal cells driven by sparse but powerful mossy fiber inputs from dentate gyrus granule cells. The neuromodulators acetylcholine and noradrenaline are separately proposed as saliency signals that dictate memory encoding but it is not known if they represent distinct signals with separate mechanisms. Here, we show experimentally that acetylcholine, and to a lesser extent noradrenaline, suppress feed-forward inhibition and enhance Excitatory-Inhibitory ratio in the mossy fiber pathway but CA3 recurrent network properties are only altered by acetylcholine. We explore the implications of these findings on CA3 ensemble formation using a hierarchy of models. In reconstructions of CA3 pyramidal cells, mossy fiber pathway disinhibition facilitates postsynaptic dendritic depolarization known to be required for synaptic plasticity at CA3-CA3 recurrent synapses. We further show in a spiking neural network model of CA3 how acetylcholine-specific network alterations can drive rapid overlapping ensemble formation. Thus, through these distinct sets of mechanisms, acetylcholine and noradrenaline facilitate the formation of neuronal ensembles in CA3 that encode salient episodic memories in the hippocampus but acetylcholine selectively enhances the density of memory storage.
Collapse
Affiliation(s)
- Luke Y. Prince
- Centre for Synaptic Plasticity, School of Physiology Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
- Mila, Montreal, Quebec, Canada
- School of Computer Science, McGill University, Montreal, Quebec, Canada
| | - Travis Bacon
- Centre for Synaptic Plasticity, School of Physiology Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Rachel Humphries
- Centre for Synaptic Plasticity, School of Physiology Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Krasimira Tsaneva-Atanasova
- Department of Mathematics and Living Systems Institute, University of Exeter, Exeter, United Kingdom
- EPRSC Centre for Predictive Modelling in Healthcare, University of Exeter, Exeter, United Kingdom
| | - Claudia Clopath
- Bioengineering Department, Imperial College London, London, United Kingdom
| | - Jack R. Mellor
- Centre for Synaptic Plasticity, School of Physiology Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
- * E-mail:
| |
Collapse
|
14
|
Ma Y, Bayguinov PO, McMahon SM, Scharfman HE, Jackson MB. Direct synaptic excitation between hilar mossy cells revealed with a targeted voltage sensor. Hippocampus 2021; 31:1215-1232. [PMID: 34478219 DOI: 10.1002/hipo.23386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 08/09/2021] [Accepted: 08/21/2021] [Indexed: 12/18/2022]
Abstract
The dentate gyrus not only gates the flow of information into the hippocampus, it also integrates and processes this information. Mossy cells (MCs) are a major type of excitatory neuron strategically located in the hilus of the dentate gyrus where they can contribute to this processing through networks of synapses with inhibitory neurons and dentate granule cells. Some prior work has suggested that MCs can form excitatory synapses with other MCs, but the role of these synapses in the network activity of the dentate gyrus has received little attention. Here, we investigated synaptic inputs to MCs in mouse hippocampal slices using a genetically encoded hybrid voltage sensor (hVOS) targeted to MCs by Cre-lox technology. This enabled optical recording of voltage changes from multiple MCs simultaneously. Stimulating granule cells and CA3 pyramidal cells activated well-established inputs to MCs and elicited synaptic responses as expected. However, the weak blockade of MC responses to granule cell layer stimulation by DCG-IV raised the possibility of another source of excitation. To evaluate synapses between MCs as this source, single MCs were stimulated focally. Stimulation of one MC above its action potential threshold evoked depolarizing responses in neighboring MCs that depended on glutamate receptors. Short latency responses of MCs to other MCs did not depend on release from granule cell axons. However, granule cells did contribute to the longer latency responses of MCs to stimulation of other MCs. Thus, MCs transmit their activity to other MCs both through direct synaptic coupling and through polysynaptic coupling with dentate granule cells. MC-MC synapses can redistribute information entering the dentate gyrus and thus shape and modulate the electrical activity underlying hippocampal functions such as navigation and memory, as well as excessive excitation during seizures.
Collapse
Affiliation(s)
- Yihe Ma
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Peter O Bayguinov
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Shane M McMahon
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Helen E Scharfman
- New York University Langone Health and the Nathan Kline Institute for Psychiatric Research, Orangeburg, New Jersey, USA
| | - Meyer B Jackson
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
15
|
Lituma PJ, Kwon HB, Alviña K, Luján R, Castillo PE. Presynaptic NMDA receptors facilitate short-term plasticity and BDNF release at hippocampal mossy fiber synapses. eLife 2021; 10:e66612. [PMID: 34061025 PMCID: PMC8186907 DOI: 10.7554/elife.66612] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 05/28/2021] [Indexed: 01/12/2023] Open
Abstract
Neurotransmitter release is a highly controlled process by which synapses can critically regulate information transfer within neural circuits. While presynaptic receptors - typically activated by neurotransmitters and modulated by neuromodulators - provide a powerful way of fine-tuning synaptic function, their contribution to activity-dependent changes in transmitter release remains poorly understood. Here, we report that presynaptic NMDA receptors (preNMDARs) at mossy fiber boutons in the rodent hippocampus can be activated by physiologically relevant patterns of activity and selectively enhance short-term synaptic plasticity at mossy fiber inputs onto CA3 pyramidal cells and mossy cells, but not onto inhibitory interneurons. Moreover, preNMDARs facilitate brain-derived neurotrophic factor release and contribute to presynaptic calcium rise. Taken together, our results indicate that by increasing presynaptic calcium, preNMDARs fine-tune mossy fiber neurotransmission and can control information transfer during dentate granule cell burst activity that normally occur in vivo.
Collapse
Affiliation(s)
- Pablo J Lituma
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Hyung-Bae Kwon
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Karina Alviña
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad Castilla-La ManchaAlbaceteSpain
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of MedicineBronxUnited States
| |
Collapse
|
16
|
Vandael D, Okamoto Y, Borges-Merjane C, Vargas-Barroso V, Suter BA, Jonas P. Subcellular patch-clamp techniques for single-bouton stimulation and simultaneous pre- and postsynaptic recording at cortical synapses. Nat Protoc 2021; 16:2947-2967. [PMID: 33990799 DOI: 10.1038/s41596-021-00526-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/01/2021] [Indexed: 02/03/2023]
Abstract
Rigorous investigation of synaptic transmission requires analysis of unitary synaptic events by simultaneous recording from presynaptic terminals and postsynaptic target neurons. However, this has been achieved at only a limited number of model synapses, including the squid giant synapse and the mammalian calyx of Held. Cortical presynaptic terminals have been largely inaccessible to direct presynaptic recording, due to their small size. Here, we describe a protocol for improved subcellular patch-clamp recording in rat and mouse brain slices, with the synapse in a largely intact environment. Slice preparation takes ~2 h, recording ~3 h and post hoc morphological analysis 2 d. Single presynaptic hippocampal mossy fiber terminals are stimulated minimally invasively in the bouton-attached configuration, in which the cytoplasmic content remains unperturbed, or in the whole-bouton configuration, in which the cytoplasmic composition can be precisely controlled. Paired pre-postsynaptic recordings can be integrated with biocytin labeling and morphological analysis, allowing correlative investigation of synapse structure and function. Paired recordings can be obtained from mossy fiber terminals in slices from both rats and mice, implying applicability to genetically modified synapses. Paired recordings can also be performed together with axon tract stimulation or optogenetic activation, allowing comparison of unitary and compound synaptic events in the same target cell. Finally, paired recordings can be combined with spontaneous event analysis, permitting collection of miniature events generated at a single identified synapse. In conclusion, the subcellular patch-clamp techniques detailed here should facilitate analysis of biophysics, plasticity and circuit function of cortical synapses in the mammalian central nervous system.
Collapse
Affiliation(s)
- David Vandael
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria
| | - Yuji Okamoto
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria
| | | | | | - Benjamin A Suter
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria
| | - Peter Jonas
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria.
| |
Collapse
|
17
|
Vandael D, Okamoto Y, Jonas P. Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses. Nat Commun 2021; 12:2912. [PMID: 34006874 PMCID: PMC8131630 DOI: 10.1038/s41467-021-23153-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 04/06/2021] [Indexed: 11/21/2022] Open
Abstract
The hippocampal mossy fiber synapse is a key synapse of the trisynaptic circuit. Post-tetanic potentiation (PTP) is the most powerful form of plasticity at this synaptic connection. It is widely believed that mossy fiber PTP is an entirely presynaptic phenomenon, implying that PTP induction is input-specific, and requires neither activity of multiple inputs nor stimulation of postsynaptic neurons. To directly test cooperativity and associativity, we made paired recordings between single mossy fiber terminals and postsynaptic CA3 pyramidal neurons in rat brain slices. By stimulating non-overlapping mossy fiber inputs converging onto single CA3 neurons, we confirm that PTP is input-specific and non-cooperative. Unexpectedly, mossy fiber PTP exhibits anti-associative induction properties. EPSCs show only minimal PTP after combined pre- and postsynaptic high-frequency stimulation with intact postsynaptic Ca2+ signaling, but marked PTP in the absence of postsynaptic spiking and after suppression of postsynaptic Ca2+ signaling (10 mM EGTA). PTP is largely recovered by inhibitors of voltage-gated R- and L-type Ca2+ channels, group II mGluRs, and vacuolar-type H+-ATPase, suggesting the involvement of retrograde vesicular glutamate signaling. Transsynaptic regulation of PTP extends the repertoire of synaptic computations, implementing a brake on mossy fiber detonation and a "smart teacher" function of hippocampal mossy fiber synapses.
Collapse
Affiliation(s)
- David Vandael
- Cellular Neuroscience, IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria.
- Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, The Netherlands.
| | - Yuji Okamoto
- Cellular Neuroscience, IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria
| | - Peter Jonas
- Cellular Neuroscience, IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria.
| |
Collapse
|
18
|
CAPS1 is involved in hippocampal synaptic plasticity and hippocampus-associated learning. Sci Rep 2021; 11:8656. [PMID: 33883618 PMCID: PMC8060421 DOI: 10.1038/s41598-021-88009-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/07/2021] [Indexed: 12/14/2022] Open
Abstract
Calcium-dependent activator protein for secretion 1 (CAPS1) is a key molecule in vesicular exocytosis, probably in the priming step. However, CAPS1's role in synaptic plasticity and brain function is elusive. Herein, we showed that synaptic plasticity and learning behavior were impaired in forebrain and/or hippocampus-specific Caps1 conditional knockout (cKO) mice by means of molecular, physiological, and behavioral analyses. Neonatal Caps1 cKO mice showed a decrease in the number of docked vesicles in the hippocampal CA3 region, with no detectable changes in the distribution of other major exocytosis-related molecules. Additionally, long-term potentiation (LTP) was partially and severely impaired in the CA1 and CA3 regions, respectively. CA1 LTP was reinforced by repeated high-frequency stimuli, whereas CA3 LTP was completely abolished. Accordingly, hippocampus-associated learning was severely impaired in adeno-associated virus (AAV) infection-mediated postnatal Caps1 cKO mice. Collectively, our findings suggest that CAPS1 is a key protein involved in the cellular mechanisms underlying hippocampal synaptic release and plasticity, which is crucial for hippocampus-associated learning.
Collapse
|
19
|
Maus L, Lee C, Altas B, Sertel SM, Weyand K, Rizzoli SO, Rhee J, Brose N, Imig C, Cooper BH. Ultrastructural Correlates of Presynaptic Functional Heterogeneity in Hippocampal Synapses. Cell Rep 2021; 30:3632-3643.e8. [PMID: 32187536 PMCID: PMC7090384 DOI: 10.1016/j.celrep.2020.02.083] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 12/15/2019] [Accepted: 02/21/2020] [Indexed: 02/06/2023] Open
Abstract
Although similar in molecular composition, synapses can exhibit strikingly distinct functional transmitter release and plasticity characteristics. To determine whether ultrastructural differences co-define this functional heterogeneity, we combine hippocampal organotypic slice cultures, high-pressure freezing, freeze substitution, and 3D-electron tomography to compare two functionally distinct synapses: hippocampal Schaffer collateral and mossy fiber synapses. We find that mossy fiber synapses, which exhibit a lower release probability and stronger short-term facilitation than Schaffer collateral synapses, harbor lower numbers of docked synaptic vesicles at active zones and a second pool of possibly tethered vesicles in their vicinity. Our data indicate that differences in the ratio of docked versus tethered vesicles at active zones contribute to distinct functional characteristics of synapses. Electron tomography enables the dissection of vesicle pools at synaptic active zones Docked and primed vesicle availability contributes to initial release probability The ratio of docked and tethered vesicles may co-determine short-term plasticity Hippocampal mossy fibers contain three morphological types of docked vesicles
Collapse
Affiliation(s)
- Lydia Maus
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Georg August University, School of Science, 37073 Göttingen, Germany
| | - ChoongKu Lee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Bekir Altas
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sinem M Sertel
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Kirsten Weyand
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - JeongSeop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
| | - Benjamin H Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
| |
Collapse
|
20
|
Retrograde Suppression of Post-Tetanic Potentiation at the Mossy Fiber-CA3 Pyramidal Cell Synapse. eNeuro 2021; 8:ENEURO.0450-20.2021. [PMID: 33593734 PMCID: PMC7986537 DOI: 10.1523/eneuro.0450-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/17/2020] [Accepted: 01/16/2021] [Indexed: 11/21/2022] Open
Abstract
In the hippocampus, the excitatory synapse between dentate granule cell (GC) axons, or mossy fibers (MFs), and CA3 pyramidal cells (MF-CA3) expresses robust forms of short-term plasticity, such as frequency facilitation and post-tetanic potentiation (PTP). These forms of plasticity are due to increases in presynaptic neurotransmitter release, and can be engaged when dentate GCs fire in bursts (e.g., during exploratory behaviors) and bring CA3 pyramidal neurons above threshold. While frequency facilitation at this synapse is limited by endogenous activation of presynaptic metabotropic glutamate receptors (mGluRs), whether MF-PTP can be regulated in an activity-dependent manner is unknown. Here, using physiologically relevant patterns of MF stimulation in acute mouse hippocampal slices, we found that disrupting postsynaptic Ca2+ dynamics increases MF-PTP, strongly suggesting a form of Ca2+-dependent retrograde suppression of this form of plasticity. PTP suppression requires a few seconds of MF bursting activity and Ca2+ release from internal stores. Our findings raise the possibility that the powerful MF-CA3 synapse can negatively regulate its own strength not only during PTP-inducing activity typical of normal exploratory behaviors, but also during epileptic activity.
Collapse
|
21
|
Groisman AI, Yang SM, Schinder AF. Differential Coupling of Adult-Born Granule Cells to Parvalbumin and Somatostatin Interneurons. Cell Rep 2021; 30:202-214.e4. [PMID: 31914387 PMCID: PMC7011182 DOI: 10.1016/j.celrep.2019.12.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/16/2019] [Accepted: 11/27/2019] [Indexed: 12/29/2022] Open
Abstract
A strong GABAergic tone imposes sparse levels of activity in the dentate gyrus of the hippocampus. This balance is challenged by the addition of new granule cells (GCs) with high excitability. How developing GCs integrate within local inhibitory networks remains unknown. We used optogenetics to study synaptogenesis between new GCs and GABAergic interneurons expressing parvalbumin (PV-INs) and somatostatin (SST-INs). PV-INs target the soma, and synapses become mature after 6 weeks. This transition is accelerated by exposure to an enriched environment. PV-INs exert efficient control of GC spiking and participate in both feedforward and feedback loops, a mechanism that would favor lateral inhibition and sparse coding. SST-INs target the dendrites, and synapses mature after 8 weeks. Outputs from GCs onto PV-INs develop faster than those onto SST-INs. Our results reveal a long-lasting transition wherein adult-born neurons remain poorly coupled to inhibition, which might enhance activity-dependent plasticity of input and output synapses. Groisman et al. examine the integration of adult-born granule cells (GCs) to inhibitory networks of the adult hippocampus. Synapse maturation is remarkably slow for parvalbumin and somatostatin interneurons, both for connections toward and from GCs. Inhibition controls the activity of new GCs late in development.
Collapse
Affiliation(s)
- Ayelén I Groisman
- Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Sung M Yang
- Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Alejandro F Schinder
- Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina.
| |
Collapse
|
22
|
Griego E, Herrera-López G, Gómez-Lira G, Barrionuevo G, Gutiérrez R, Galván EJ. Functional expression of TrkB receptors on interneurones and pyramidal cells of area CA3 of the rat hippocampus. Neuropharmacology 2020; 182:108379. [PMID: 33130041 DOI: 10.1016/j.neuropharm.2020.108379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/09/2020] [Accepted: 10/29/2020] [Indexed: 12/13/2022]
Abstract
The dentate gyrus and hippocampal area CA3 region of the mammalian brain contains the highest levels of brain-derived neurotrophic factor (BDNF) and its canonical membrane receptor, tropomyosin-related kinase B (TrkB). Therefore, the present study examines the expression and physiological responses triggered by activation of TrkB on hippocampal area CA3 interneurones and pyramidal cells of the rat hippocampus. Triple immunolabelling for TrkB, glutamate decarboxylase 67, and the calcium-binding proteins parvalbumin, calbindin or calretinin confirms the somatic expression of TrkB in all CA3 sublayers. TrkB-positive interneurones with fast-spiking discharge are restricted to strata oriens and lucidum, whereas regular-spiking interneurones are found in the strata lucidum, radiatum and lacunosum-moleculare. Activation of TrkB receptors with 7,8-dihydroxyflavone (DHF) modulates amplitude and frequency of spontaneous synaptic currents recorded from CA3 interneurones. Furthermore, the isolated excitatory postsynaptic currents (EPSC) of CA3 interneurones evoked by the mossy fibres (MF) or commissural/associational (C/A) axons, show input-specific synaptic potentiation in response to TrkB stimulation. On CA3 pyramidal cells, stimulation with DHF potentiates the MF synaptic transmission and increases the MF-EPSP - spike coupling. The latter exhibits a dramatic increase when picrotoxin is bath perfused after DHF, indicating that local interneurones restrain the excitability mediated by activation of TrkB. Therefore, we propose that release of BDNF on area CA3 reshapes the output of this hippocampal region by simultaneous activation of TrkB on GABAergic interneurones and pyramidal cells.
Collapse
Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, Cinvestav Sur, México City, México
| | | | | | - Germán Barrionuevo
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, United States
| | - Rafael Gutiérrez
- Departamento de Farmacobiología, Cinvestav Sur, México City, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sur, México City, México.
| |
Collapse
|
23
|
Lugarà E, Kaushik R, Leite M, Chabrol E, Dityatev A, Lignani G, Walker MC. LGI1 downregulation increases neuronal circuit excitability. Epilepsia 2020; 61:2836-2846. [DOI: 10.1111/epi.16736] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/29/2020] [Accepted: 09/29/2020] [Indexed: 12/19/2022]
Affiliation(s)
- Eleonora Lugarà
- Department of Clinical and Experimental Epilepsy UCL Queen Square Institute of Neurology London UK
| | - Rahul Kaushik
- German Center for Neurodegenerative Diseases Magdeburg Germany
- Center for Behavioral Brain Sciences Magdeburg Germany
| | - Marco Leite
- Department of Clinical and Experimental Epilepsy UCL Queen Square Institute of Neurology London UK
| | - Elodie Chabrol
- Department of Clinical and Experimental Epilepsy UCL Queen Square Institute of Neurology London UK
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases Magdeburg Germany
- Center for Behavioral Brain Sciences Magdeburg Germany
- Medical Faculty Otto von Guericke University Magdeburg Germany
| | - Gabriele Lignani
- Department of Clinical and Experimental Epilepsy UCL Queen Square Institute of Neurology London UK
| | - Matthew C. Walker
- Department of Clinical and Experimental Epilepsy UCL Queen Square Institute of Neurology London UK
| |
Collapse
|
24
|
Oldani S, Moreno-Velasquez L, Faiss L, Stumpf A, Rosenmund C, Schmitz D, Rost BR. SynaptoPAC, an optogenetic tool for induction of presynaptic plasticity. J Neurochem 2020; 156:324-336. [PMID: 33037623 DOI: 10.1111/jnc.15210] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 09/21/2020] [Accepted: 10/01/2020] [Indexed: 11/26/2022]
Abstract
Optogenetic manipulations have transformed neuroscience in recent years. While sophisticated tools now exist for controlling the firing patterns of neurons, it remains challenging to optogenetically define the plasticity state of individual synapses. A variety of synapses in the mammalian brain express presynaptic long-term potentiation (LTP) upon elevation of presynaptic cyclic adenosine monophosphate (cAMP), but the molecular expression mechanisms as well as the impact of presynaptic LTP on network activity and behavior are not fully understood. In order to establish optogenetic control of presynaptic cAMP levels and thereby presynaptic potentiation, we developed synaptoPAC, a presynaptically targeted version of the photoactivated adenylyl cyclase bPAC. In cultures of hippocampal granule cells of Wistar rats, activation of synaptoPAC with blue light increased action potential-evoked transmission, an effect not seen in hippocampal cultures of non-granule cells. In acute brain slices of C57BL/6N mice, synaptoPAC activation immediately triggered a strong presynaptic potentiation at mossy fiber synapses in CA3, but not at Schaffer collateral synapses in CA1. Following light-triggered potentiation, mossy fiber transmission decreased within 20 min, but remained enhanced still after 30 min. The optogenetic potentiation altered the short-term plasticity dynamics of release, reminiscent of presynaptic LTP. Our work establishes synaptoPAC as an optogenetic tool that enables acute light-controlled potentiation of transmitter release at specific synapses in the brain, facilitating studies of the role of presynaptic potentiation in network function and animal behavior in an unprecedented manner. Read the Editorial Highlight for this article on page 270.
Collapse
Affiliation(s)
- Silvia Oldani
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Laura Moreno-Velasquez
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Lukas Faiss
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Alexander Stumpf
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Christian Rosenmund
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Dietmar Schmitz
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany.,Max-Delbruck-Centrum (MDC) for Molecular Medicine in the Helmholtz Association, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Benjamin R Rost
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| |
Collapse
|
25
|
Griego E, Galván EJ. Metabotropic Glutamate Receptors at the Aged Mossy Fiber - CA3 Synapse of the Hippocampus. Neuroscience 2020; 456:95-105. [PMID: 31917351 DOI: 10.1016/j.neuroscience.2019.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/28/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are a group of G-protein-coupled receptors that exert a broad array of modulatory actions at excitatory synapses of the central nervous system. In the hippocampus, the selective activation of the different mGluRs modulates the intrinsic excitability, the strength of synaptic transmission, and induces multiple forms of long-term plasticity. Despite the relevance of mGluRs in the normal function of the hippocampus, we know very little about the changes that mGluRs functionality undergoes during the non-pathological aging. Here, we review data concerning the physiological actions of mGluRs, with particular emphasis on hippocampal area CA3. Later, we examine changes in the expression and functionality of mGluRs during the aging process. We complement this review with original data showing an array of electrophysiological modifications observed in the synaptic transmission and intrinsic excitability of aged CA3 pyramidal cells in response to the pharmacological stimulation of the different mGluRs.
Collapse
Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico
| | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico.
| |
Collapse
|
26
|
Viotti JS, Dresbach T. Differential Effect on Hippocampal Synaptic Facilitation by the Presynaptic Protein Mover. Front Synaptic Neurosci 2019; 11:30. [PMID: 31803042 PMCID: PMC6873103 DOI: 10.3389/fnsyn.2019.00030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/31/2019] [Indexed: 01/23/2023] Open
Abstract
Neurotransmitter release relies on an evolutionarily conserved presynaptic machinery. Nonetheless, some proteins occur in certain species and synapses, and are absent in others, indicating that they may have modulatory roles. How such proteins expand the power or versatility of the core release machinery is unclear. The presynaptic protein Mover/TPRGL/SVAP30 is heterogeneously expressed among synapses of the rodent brain, suggesting that it may add special functions to subtypes of presynaptic terminals. Mover is a synaptic vesicle-attached phosphoprotein that binds to Calmodulin and the active zone scaffolding protein Bassoon. Here we use a Mover knockout mouse line to investigate the role of Mover in the hippocampal mossy fiber (MF) to CA3 pyramidal cell synapse and Schaffer collateral to CA1. While Schaffer collateral synapses were unchanged by the knockout, the MFs showed strongly increased facilitation. The effect of Mover knockout in facilitation was both calcium- and age-dependent, having a stronger effect at higher calcium concentrations and in younger animals. Increasing cyclic adenosine monophosphate (cAMP) levels by forskolin equally potentiated both wildtype and knockout MF synapses, but occluded the increased facilitation observed in the knockout. These discoveries suggest that Mover has distinct roles at different synapses. At MF terminals, it acts to constrain the extent of presynaptic facilitation.
Collapse
Affiliation(s)
| | - Thomas Dresbach
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| |
Collapse
|
27
|
Hoshino K, Hasegawa K, Kamiya H, Morimoto Y. Synapse-specific effects of IL-1β on long-term potentiation in the mouse hippocampus. Biomed Res 2018. [PMID: 28637953 DOI: 10.2220/biomedres.38.183] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Interleukin-1β (IL-1β) is a key molecule in the inflammatory responses elicited during infection and injury. It exerts local effects on synaptic plasticity by binding to IL-1 receptors that are expressed at high levels in the hippocampus. We examined the effects of IL-1β on synaptic plasticity in different hippocampal regions in acute mouse brain slices by measuring long-term potentiation (LTP). IL-1β (1 ng/mL) was applied for 30 min before LTP was induced with high-frequency stimulation (HFS). LTP was significantly impaired by either IL-1β application to the Schaffer collateral-CA1 synapses or the associational/commissural (A/C) fiber-CA3 synapses, which are both dependent on N-methyl-D-aspartate (NMDA) receptor activation. However, mossy fiber-CA3 LTP, which is expressed presynaptically in an NMDA-independent manner, was not impaired by IL-1β. Our results demonstrate that IL-1β exerts variable effects on LTP at different kinds of synapses, indicating that IL-1β has synapse-specific effects on hippocampal synaptic plasticity.
Collapse
Affiliation(s)
- Koji Hoshino
- Department of Anesthesiology and Cristical Care Medicine, Hokkaido University Graduate School of medicine.,Department of Neurobiology, Hokkaido University Graduate School of Medicine
| | - Kan Hasegawa
- Department of Anesthesiology and Cristical Care Medicine, Hokkaido University Graduate School of medicine.,Department of Neurobiology, Hokkaido University Graduate School of Medicine
| | - Haruyuki Kamiya
- Department of Neurobiology, Hokkaido University Graduate School of Medicine
| | - Yuji Morimoto
- Department of Anesthesiology and Cristical Care Medicine, Hokkaido University Graduate School of medicine
| |
Collapse
|
28
|
Guo N, Soden ME, Herber C, Kim MT, Besnard A, Lin P, Ma X, Cepko CL, Zweifel LS, Sahay A. Dentate granule cell recruitment of feedforward inhibition governs engram maintenance and remote memory generalization. Nat Med 2018. [PMID: 29529016 PMCID: PMC5893385 DOI: 10.1038/nm.4491] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Memories become less precise and generalize over time as memory traces re-organize in hippocampal-cortical networks. Increased time-dependent loss of memory precision characterizes overgeneralization of fear in post-traumatic stress disorder (PTSD) and age-related cognitive impairments. In the hippocampal dentate gyrus (DG), memories are thought to be encoded by so-called “engram-bearing” dentate granule cells (eDGCs). Here we show using rodents that contextual fear conditioning increases connectivity between eDGCs and inhibitory interneurons in the downstream hippocampal CA3 region. We identify actin-binding LIM protein 3 (abLIM3) as a mossy fiber terminal localized cytoskeletal factor, whose levels decrease upon learning. Downregulation of abLIM3 in DGCs was sufficient to increase connectivity with CA3 stratum lucidum interneurons (SLINs), promote parvalbumin (PV) SLIN activation, enhance feed-forward inhibition onto CA3, and maintain a fear memory engram in the dentate gyrus (DG) over time. Furthermore, abLIM3 downregulation in DGCs conferred conditioned context-specific reactivation of memory traces in hippocampal-cortical and amygdalar networks and decreased fear memory generalization at remote time points. Consistent with age-related hyperactivity of CA3, learning failed to increase DGC-SLIN connectivity in 17 month-old mice, whereas abLIM3 downregulation was sufficient to restore DGC-SLIN connectivity, increase PV-SLIN activation and improve remote memory precision. These studies exemplify a connectivity-based strategy targeting a molecular brake of feedforward inhibition in DG-CA3 that may be harnessed to decrease time-dependent memory generalization in PTSD and improve memory precision in aging.
Collapse
Affiliation(s)
- Nannan Guo
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Marta E Soden
- Department of Pharmacology, University of Washington, Seattle, Washington, USA.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA
| | - Charlotte Herber
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Michael TaeWoo Kim
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Antoine Besnard
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Paoyan Lin
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Xiang Ma
- Howard Hughes Medical Institute, Boston, Massachusetts, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Constance L Cepko
- Howard Hughes Medical Institute, Boston, Massachusetts, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Larry S Zweifel
- Department of Pharmacology, University of Washington, Seattle, Washington, USA.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,BROAD Institute of Harvard and Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, USA
| |
Collapse
|
29
|
Weng FJ, Garcia RI, Lutzu S, Alviña K, Zhang Y, Dushko M, Ku T, Zemoura K, Rich D, Garcia-Dominguez D, Hung M, Yelhekar TD, Sørensen AT, Xu W, Chung K, Castillo PE, Lin Y. Npas4 Is a Critical Regulator of Learning-Induced Plasticity at Mossy Fiber-CA3 Synapses during Contextual Memory Formation. Neuron 2018; 97:1137-1152.e5. [PMID: 29429933 PMCID: PMC5843542 DOI: 10.1016/j.neuron.2018.01.026] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 11/26/2017] [Accepted: 01/11/2018] [Indexed: 11/18/2022]
Abstract
Synaptic connections between hippocampal mossy fibers (MFs) and CA3 pyramidal neurons are essential for contextual memory encoding, but the molecular mechanisms regulating MF-CA3 synapses during memory formation and the exact nature of this regulation are poorly understood. Here we report that the activity-dependent transcription factor Npas4 selectively regulates the structure and strength of MF-CA3 synapses by restricting the number of their functional synaptic contacts without affecting the other synaptic inputs onto CA3 pyramidal neurons. Using an activity-dependent reporter, we identified CA3 pyramidal cells that were activated by contextual learning and found that MF inputs on these cells were selectively strengthened. Deletion of Npas4 prevented both contextual memory formation and this learning-induced synaptic modification. We further show that Npas4 regulates MF-CA3 synapses by controlling the expression of the polo-like kinase Plk2. Thus, Npas4 is a critical regulator of experience-dependent, structural, and functional plasticity at MF-CA3 synapses during contextual memory formation.
Collapse
Affiliation(s)
- Feng-Ju Weng
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Rodrigo I Garcia
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Stefano Lutzu
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Karina Alviña
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yuxiang Zhang
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Margaret Dushko
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Taeyun Ku
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA; Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA
| | - Khaled Zemoura
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - David Rich
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Dario Garcia-Dominguez
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Matthew Hung
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Tushar D Yelhekar
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Andreas Toft Sørensen
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Weifeng Xu
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Kwanghun Chung
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA; Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA; Department of Chemical Engineering, MIT, Cambridge, MA, USA; Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA, USA
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yingxi Lin
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
| |
Collapse
|
30
|
Shan W, Nagai T, Tanaka M, Itoh N, Furukawa-Hibi Y, Nabeshima T, Sokabe M, Yamada K. Neuronal PAS domain protein 4 (Npas4) controls neuronal homeostasis in pentylenetetrazole-induced epilepsy through the induction of Homer1a. J Neurochem 2017; 145:19-33. [DOI: 10.1111/jnc.14274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/27/2017] [Accepted: 11/29/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Wei Shan
- Department of Neuropsychopharmacology and Hospital Pharmacy; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Taku Nagai
- Department of Neuropsychopharmacology and Hospital Pharmacy; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Motoki Tanaka
- Mechanobiology Laboratory; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Norimichi Itoh
- Department of Neuropsychopharmacology and Hospital Pharmacy; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Yoko Furukawa-Hibi
- Department of Neuropsychopharmacology and Hospital Pharmacy; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory; Graduate School of Health Sciences; Fujita Health University; Toyoake Japan
- Aino University; Ibaraki Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Kiyofumi Yamada
- Department of Neuropsychopharmacology and Hospital Pharmacy; Nagoya University Graduate School of Medicine; Nagoya Japan
| |
Collapse
|
31
|
Dammann F, Kirschstein T, Guli X, Müller S, Porath K, Rohde M, Tokay T, Köhling R. Bidirectional shift of group III metabotropic glutamate receptor-mediated synaptic depression in the epileptic hippocampus. Epilepsy Res 2017; 139:157-163. [PMID: 29224956 DOI: 10.1016/j.eplepsyres.2017.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/08/2017] [Accepted: 12/02/2017] [Indexed: 01/20/2023]
Abstract
A common function of group III metabotropic glutamate receptors (mGluRs) located at the presynaptic site of a glutamatergic synapse is synaptic depression. Here, we studied synaptic depression mediated by group III mGluR activation at Schaffer collateral-CA1 (SC-CA1) synapses and associational-commissural-CA3 (AC-CA3) synapses by recording field excitatory postsynaptic potentials in the in vitro brain slice preparation. In order to gauge the impact of synaptic depression in chronically epileptic tissue, we compared rats after pilocarpine-induced status epilepticus (post-SE) with control animals. We observed that synaptic transmission at control AC-CA3 synapses was sensitive to the group III mGluR agonist L-AP4 (10μM), while there was no effect of this compound at SC-CA1 synapses in the same tissue. In contrast, synaptic depression at AC-CA3 synapses by L-AP4 was lost in chronically epileptic tissue, and we found a significant synaptic depression at SC-CA1 synapses in post-SE tissue by L-AP4 and by the mGluR8-selective agonist DCPG. The depression by L-AP4 and DCPG in CA1 was also demonstrated in immature control tissue suggesting developmental down-regulation of mGluR8 at this synapse as well as re-appearance of this isoform under pathological conditions. Quantitative real-time RT-PCR was used to identify mGluR isoforms and to assess their transcriptional changes in post-SE tissue. These analyses revealed down-regulation of mGluR4 and mGluR6 at AC-CA3 and up-regulation of mGluR8 at SC-CA1 synapses. We conclude that group III mGluR-mediated synaptic depression is differentially altered in chronically epileptic tissue by a bidirectional shift of the transcriptional level.
Collapse
Affiliation(s)
- Fabian Dammann
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Timo Kirschstein
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany.
| | - Xiati Guli
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Steffen Müller
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Katrin Porath
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Marco Rohde
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Tursonjan Tokay
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| | - Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock, Germany
| |
Collapse
|
32
|
Jin LE, Wang M, Yang ST, Yang Y, Galvin VC, Lightbourne TC, Ottenheimer D, Zhong Q, Stein J, Raja A, Paspalas CD, Arnsten AFT. mGluR2/3 mechanisms in primate dorsolateral prefrontal cortex: evidence for both presynaptic and postsynaptic actions. Mol Psychiatry 2017; 22:1615-1625. [PMID: 27502475 PMCID: PMC5298940 DOI: 10.1038/mp.2016.129] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/04/2016] [Accepted: 06/15/2016] [Indexed: 01/12/2023]
Abstract
Cognitive deficits in psychiatric and age-related disorders generally involve dysfunction of the dorsolateral prefrontal cortex (dlPFC), but there are few treatments for these debilitating symptoms. Group II metabotropic glutamate receptors (mGluR2/3), which couple to Gi/Go, have been a focus of therapeutics based on rodent research, where mGluR2/3 have been shown to reduce axonal glutamate release and increase glial glutamate uptake. However, this strategy has had mixed results in patients, and understanding mGluR2/3 mechanisms in primates will help guide therapeutic interventions. The current study examined mGluR2/3 localization and actions in the primate dlPFC layer III circuits underlying working memory, where the persistent firing of 'Delay cells' is mediated by N-methyl-d-aspartate receptors and weakened by cAMP-PKA-potassium channel signaling in dendritic spines. Immunoelectron microscopy identified postsynaptic mGluR2/3 in the spines, in addition to the traditional presynaptic and astrocytic locations. In vivo iontophoretic application of the mGluR2/3 agonists (2R, 4R)-APDC or LY379268 onto dlPFC Delay cells produced an inverted-U effect on working memory representation, with enhanced neuronal firing following low doses of mGluR2/3 agonists. The enhancing effects were reversed by an mGluR2/3 antagonist or by activating cAMP signaling, consistent with mGluR2/3 inhibiting postsynaptic cAMP signaling in spines. Systemic administration of these agonists to monkeys performing a working memory task also produced an inverted-U dose-response, where low doses improved performance but higher doses, similar to clinical trials, had mixed effects. Our data suggest that low doses of mGluR2/3 stimulation may have therapeutic effects through unexpected postsynaptic actions in dlPFC, strengthening synaptic connections and improving cognitive function.
Collapse
Affiliation(s)
- L E Jin
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - M Wang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - S-T Yang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Y Yang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - V C Galvin
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - T C Lightbourne
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - D Ottenheimer
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Q Zhong
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - J Stein
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - A Raja
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - C D Paspalas
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA,Department of Neuroscience, Yale School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA. E-mail: or
| | - A F T Arnsten
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA,Department of Neuroscience, Yale School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA. E-mail: or
| |
Collapse
|
33
|
Sun Q, Sotayo A, Cazzulino AS, Snyder AM, Denny CA, Siegelbaum SA. Proximodistal Heterogeneity of Hippocampal CA3 Pyramidal Neuron Intrinsic Properties, Connectivity, and Reactivation during Memory Recall. Neuron 2017; 95:656-672.e3. [PMID: 28772124 DOI: 10.1016/j.neuron.2017.07.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 05/25/2017] [Accepted: 07/12/2017] [Indexed: 12/21/2022]
Abstract
The hippocampal CA3 region is classically viewed as a homogeneous autoassociative network critical for associative memory and pattern completion. However, recent evidence has demonstrated a striking heterogeneity along the transverse, or proximodistal, axis of CA3 in spatial encoding and memory. Here we report the presence of striking proximodistal gradients in intrinsic membrane properties and synaptic connectivity for dorsal CA3. A decreasing gradient of mossy fiber synaptic strength along the proximodistal axis is mirrored by an increasing gradient of direct synaptic excitation from entorhinal cortex. Furthermore, we uncovered a nonuniform pattern of reactivation of fear memory traces, with the most robust reactivation during memory retrieval occurring in mid-CA3 (CA3b), the region showing the strongest net recurrent excitation. Our results suggest that heterogeneity in both intrinsic properties and synaptic connectivity may contribute to the distinct spatial encoding and behavioral role of CA3 subregions along the proximodistal axis.
Collapse
Affiliation(s)
- Qian Sun
- Department of Neuroscience, Columbia University, New York, NY 10032, USA.
| | - Alaba Sotayo
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
| | - Alejandro S Cazzulino
- Department of Psychiatry, Columbia University, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute (NYSPI)/Research Foundation for Mental Hygiene, Inc. (RFMH), New York, NY 10032, USA
| | - Anna M Snyder
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
| | - Christine A Denny
- Department of Psychiatry, Columbia University, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute (NYSPI)/Research Foundation for Mental Hygiene, Inc. (RFMH), New York, NY 10032, USA
| | - Steven A Siegelbaum
- Department of Neuroscience, Columbia University, New York, NY 10032, USA; Department of Pharmacology, Columbia University, New York, NY 10032, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10032, USA.
| |
Collapse
|
34
|
Khrimian L, Obri A, Ramos-Brossier M, Rousseaud A, Moriceau S, Nicot AS, Mera P, Kosmidis S, Karnavas T, Saudou F, Gao XB, Oury F, Kandel E, Karsenty G. Gpr158 mediates osteocalcin's regulation of cognition. J Exp Med 2017; 214:2859-2873. [PMID: 28851741 PMCID: PMC5626410 DOI: 10.1084/jem.20171320] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/01/2017] [Accepted: 08/03/2017] [Indexed: 02/01/2023] Open
Abstract
This study by Khrimian et al. demonstrates that the bone-derived hormone osteocalcin is necessary and sufficient to correct age-related cognitive decline in the mouse. It also provides genetic, molecular, and neurophysiological evidence that Gpr158 is the receptor mediating osteocalcin’s regulation of cognition. That osteocalcin (OCN) is necessary for hippocampal-dependent memory and to prevent anxiety-like behaviors raises novel questions. One question is to determine whether OCN is also sufficient to improve these behaviors in wild-type mice, when circulating levels of OCN decline as they do with age. Here we show that the presence of OCN is necessary for the beneficial influence of plasma from young mice when injected into older mice on memory and that peripheral delivery of OCN is sufficient to improve memory and decrease anxiety-like behaviors in 16-mo-old mice. A second question is to identify a receptor transducing OCN signal in neurons. Genetic, electrophysiological, molecular, and behavioral assays identify Gpr158, an orphan G protein–coupled receptor expressed in neurons of the CA3 region of the hippocampus, as transducing OCN’s regulation of hippocampal-dependent memory in part through inositol 1,4,5-trisphosphate and brain-derived neurotrophic factor. These results indicate that exogenous OCN can improve hippocampal-dependent memory in mice and identify molecular tools to harness this pathway for therapeutic purposes.
Collapse
Affiliation(s)
- Lori Khrimian
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| | - Arnaud Obri
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| | - Mariana Ramos-Brossier
- Institut Necker-Enfants Malades, CS 61431, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1151, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Audrey Rousseaud
- Institut Necker-Enfants Malades, CS 61431, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1151, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Stéphanie Moriceau
- Institut Necker-Enfants Malades, CS 61431, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1151, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Anne-Sophie Nicot
- Grenoble Institute des Neurosciences, Université Grenoble Alpes, Grenoble, France.,INSERM, U1216, Grenoble, France
| | - Paula Mera
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| | - Stylianos Kosmidis
- Department of Neuroscience, Columbia University Medical Center, New York, NY.,Howard Hughes Medical Institute, Columbia University, New York, NY.,New York State Psychiatric Institute, New York, NY
| | - Theodoros Karnavas
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| | - Frederic Saudou
- Grenoble Institute des Neurosciences, Université Grenoble Alpes, Grenoble, France.,INSERM, U1216, Grenoble, France.,CHU Grenoble Alpes, Grenoble, France
| | - Xiao-Bing Gao
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT
| | - Franck Oury
- Institut Necker-Enfants Malades, CS 61431, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1151, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Eric Kandel
- Department of Neuroscience, Columbia University Medical Center, New York, NY.,Kavli Institute for Brain Science, Columbia University Medical Center, New York, NY.,Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY.,New York State Psychiatric Institute, New York, NY
| | - Gerard Karsenty
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| |
Collapse
|
35
|
Activation of Group II Metabotropic Glutamate Receptors Promotes LTP Induction at Schaffer Collateral-CA1 Pyramidal Cell Synapses by Priming NMDA Receptors. J Neurosci 2017; 36:11521-11531. [PMID: 27911756 DOI: 10.1523/jneurosci.1519-16.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 09/20/2016] [Accepted: 09/23/2016] [Indexed: 12/31/2022] Open
Abstract
It is well established that selective activation of group I metabotropic glutamate (mGlu) receptors induces LTD of synaptic transmission at Schaffer collateral-CA1 synapses. In contrast, application of 1S,3R-ACPD, a mixed agonist at group I and group II mGlu receptors, induces LTP. Using whole-cell recordings from CA1 pyramidal cells and field recordings in the hippocampal CA1 region, we investigated the specific contribution of group II mGlu receptors to synaptic plasticity at Schaffer collateral-CA1 synapses in acute slices of adult mice. Pharmacological activation of group II mGlu receptors (mGlu2 and mGlu3 receptors) with the specific agonist LY354740 in conjunction with electrical stimulation induced postsynaptic LTP. This form of plasticity requires coactivation of NMDA receptors (NMDARs). Group II mGlu receptor activation led to PKC-dependent phosphorylation of the GluN1 subunit. We found that both synaptic and extrasynaptic NMDARs, which are differentially modulated by mGlu2 and mGlu3 receptors, contribute to LTP induction. Furthermore, LTP initiated by activation of group II mGlu receptors was not occluded by LTP induced with high-frequency trains of stimuli. However, the phosphorylation of NMDARs mediated by group II mGlu receptor activation led to a priming effect that enhanced subsequent high-frequency stimulation-induced LTP. These findings reveal a novel metaplastic mechanism through which group II mGlu receptors modulate synaptic function at the Schaffer collateral input to CA1 pyramidal cells, thereby lowering the threshold to induce plasticity. SIGNIFICANCE STATEMENT The group II metabotropic glutamate (mGlu II) receptors exert a well characterized action on presynaptic neuron terminals to modulate neurotransmitter release. Here, we show that these receptors also have postsynaptic effects in promoting the induction of synaptic plasticity. Using an electrophysiological approach including field and whole-cell patch recording in hippocampi from wild-type and transgenic mice, we show that activation of group II mGlu receptors enhances NMDA receptor (NMDAR)-mediated currents through PKC-dependent phosphorylation. This priming of NMDARs lowers the threshold for the induction of LTP of synaptic transmission. These findings may also provide new insights into the mechanisms through which drugs targeting mGlu II receptors alleviate hypoglutamatergic conditions such as those occurring in certain brain disorders such as schizophrenia.
Collapse
|
36
|
Lee SH, Lutz D, Mossalam M, Bolshakov VY, Frotscher M, Shen J. Presenilins regulate synaptic plasticity and mitochondrial calcium homeostasis in the hippocampal mossy fiber pathway. Mol Neurodegener 2017; 12:48. [PMID: 28619096 PMCID: PMC5472971 DOI: 10.1186/s13024-017-0189-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/08/2017] [Indexed: 11/24/2022] Open
Abstract
Background Presenilins play a major role in the pathogenesis of Alzheimer’s disease, in which the hippocampus is particularly vulnerable. Previous studies of Presenilin function in the synapse, however, focused exclusively on the hippocampal Schaffer collateral (SC) pathway. Whether Presenilins play similar or distinct roles in other hippocampal synapses is unknown. Methods To investigate the role of Presenilins at mossy fiber (MF) synapses we performed field and whole-cell electrophysiological recordings and Ca2+ imaging using acute hippocampal slices of postnatal forebrain-restricted Presenilin conditional double knockout (PS cDKO) and control mice at 2 months of age. We also performed quantitative electron microscopy (EM) analysis to determine whether mitochondrial content is affected at presynaptic MF boutons of PS cDKO mice. We further conducted behavioral analysis to assess spatial learning and memory of PS cDKO and control mice at 2 months in the Morris water maze. Results We found that long-term potentiation and short-term plasticity, such as paired-pulse and frequency facilitation, are impaired at MF synapses of PS cDKO mice. Moreover, post-tetanic potentiation (PTP), another form of short-term plasticity, is also impaired at MF synapses of PS cDKO mice. Furthermore, blockade of mitochondrial Ca2+ efflux mimics and occludes the PTP deficits at MF synapses of PS cDKO mice, suggesting that mitochondrial Ca2+ homeostasis is impaired in the absence of PS. Quantitative EM analysis showed normal number and area of mitochondria at presynaptic MF boutons of PS cDKO mice, indicating unchanged mitochondrial content. Ca2+ imaging of dentate gyrus granule neurons further revealed that cytosolic Ca2+ increases induced by tetanic stimulation are reduced in PS cDKO granule neurons in acute hippocampal slices, and that inhibition of mitochondrial Ca2+ release during high frequency stimulation mimics and occludes the Ca2+ defects observed in PS cDKO neurons. Consistent with synaptic plasticity impairment observed at MF and SC synapses in acute PS cDKO hippocampal slices, PS cDKO mice exhibit profound spatial learning and memory deficits in the Morris water maze. Conclusions Our findings demonstrate the importance of PS in the regulation of synaptic plasticity and mitochondrial Ca2+ homeostasis in the hippocampal MF pathway.
Collapse
Affiliation(s)
- Sang Hun Lee
- Department of Neurology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
| | - David Lutz
- Institute for Structural Neurobiology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, D-20246, Hamburg, Germany
| | - Mohanad Mossalam
- Department of Neurology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Vadim Y Bolshakov
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, MA, 02478, USA.,Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA
| | - Michael Frotscher
- Institute for Structural Neurobiology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, D-20246, Hamburg, Germany
| | - Jie Shen
- Department of Neurology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA. .,Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.
| |
Collapse
|
37
|
Dietary Supplementation of Hericium erinaceus Increases Mossy Fiber-CA3 Hippocampal Neurotransmission and Recognition Memory in Wild-Type Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 2017:3864340. [PMID: 28115973 PMCID: PMC5237458 DOI: 10.1155/2017/3864340] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/01/2016] [Accepted: 12/07/2016] [Indexed: 01/25/2023]
Abstract
Hericium erinaceus (Bull.) Pers. is a medicinal mushroom capable of inducing a large number of modulatory effects on human physiology ranging from the strengthening of the immune system to the improvement of cognitive functions. In mice, dietary supplementation with H. erinaceus prevents the impairment of spatial short-term and visual recognition memory in an Alzheimer model. Intriguingly other neurobiological effects have recently been reported like the effect on neurite outgrowth and differentiation in PC12 cells. Until now no investigations have been conducted to assess the impact of this dietary supplementation on brain function in healthy subjects. Therefore, we have faced the problem by considering the effect on cognitive skills and on hippocampal neurotransmission in wild-type mice. In wild-type mice the oral supplementation with H. erinaceus induces, in behaviour test, a significant improvement in the recognition memory and, in hippocampal slices, an increase in spontaneous and evoked excitatory synaptic current in mossy fiber-CA3 synapse. In conclusion, we have produced a series of findings in support of the concept that H. erinaceus induces a boost effect onto neuronal functions also in nonpathological conditions.
Collapse
|
38
|
Villanueva-Castillo C, Tecuatl C, Herrera-López G, Galván EJ. Aging-related impairments of hippocampal mossy fibers synapses on CA3 pyramidal cells. Neurobiol Aging 2016; 49:119-137. [PMID: 27794263 DOI: 10.1016/j.neurobiolaging.2016.09.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 11/16/2022]
Abstract
The network interaction between the dentate gyrus and area CA3 of the hippocampus is responsible for pattern separation, a process that underlies the formation of new memories, and which is naturally diminished in the aged brain. At the cellular level, aging is accompanied by a progression of biochemical modifications that ultimately affects its ability to generate and consolidate long-term potentiation. Although the synapse between dentate gyrus via the mossy fibers (MFs) onto CA3 neurons has been subject of extensive studies, the question of how aging affects the MF-CA3 synapse is still unsolved. Extracellular and whole-cell recordings from acute hippocampal slices of aged Wistar rats (34 ± 2 months old) show that aging is accompanied by a reduction in the interneuron-mediated inhibitory mechanisms of area CA3. Several MF-mediated forms of short-term plasticity, MF long-term potentiation and at least one of the critical signaling cascades necessary for potentiation are also compromised in the aged brain. An analysis of the spontaneous glutamatergic and gamma-aminobutyric acid-mediated currents on CA3 cells reveal a dramatic alteration in amplitude and frequency of the nonevoked events. CA3 cells also exhibited increased intrinsic excitability. Together, these results demonstrate that aging is accompanied by a decrease in the GABAergic inhibition, reduced expression of short- and long-term forms of synaptic plasticity, and increased intrinsic excitability.
Collapse
Affiliation(s)
| | - Carolina Tecuatl
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México
| | | | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México.
| |
Collapse
|
39
|
Symmetric spike timing-dependent plasticity at CA3-CA3 synapses optimizes storage and recall in autoassociative networks. Nat Commun 2016; 7:11552. [PMID: 27174042 PMCID: PMC4869174 DOI: 10.1038/ncomms11552] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 04/06/2016] [Indexed: 01/23/2023] Open
Abstract
CA3–CA3 recurrent excitatory synapses are thought to play a key role in memory storage and pattern completion. Whether the plasticity properties of these synapses are consistent with their proposed network functions remains unclear. Here, we examine the properties of spike timing-dependent plasticity (STDP) at CA3–CA3 synapses. Low-frequency pairing of excitatory postsynaptic potentials (EPSPs) and action potentials (APs) induces long-term potentiation (LTP), independent of temporal order. The STDP curve is symmetric and broad (half-width ∼150 ms). Consistent with these STDP induction properties, AP–EPSP sequences lead to supralinear summation of spine [Ca2+] transients. Furthermore, afterdepolarizations (ADPs) following APs efficiently propagate into dendrites of CA3 pyramidal neurons, and EPSPs summate with dendritic ADPs. In autoassociative network models, storage and recall are more robust with symmetric than with asymmetric STDP rules. Thus, a specialized STDP induction rule allows reliable storage and recall of information in the hippocampal CA3 network. STDP is dependent on the timing of pre- and post-synaptic activity. Here, the authors describe a symmetric STDP induction rule at CA3-CA3 synapses, which induces LTP over a broad range of paring intervals. Modelling suggests that this STDP rule may enhance storage capacity and pattern completion in the CA3 cell network.
Collapse
|
40
|
Schmitz SK, King C, Kortleven C, Huson V, Kroon T, Kevenaar JT, Schut D, Saarloos I, Hoetjes JP, de Wit H, Stiedl O, Spijker S, Li KW, Mansvelder HD, Smit AB, Cornelisse LN, Verhage M, Toonen RF. Presynaptic inhibition upon CB1 or mGlu2/3 receptor activation requires ERK/MAPK phosphorylation of Munc18-1. EMBO J 2016; 35:1236-50. [PMID: 27056679 DOI: 10.15252/embj.201592244] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 03/02/2016] [Indexed: 01/22/2023] Open
Abstract
Presynaptic cannabinoid (CB1R) and metabotropic glutamate receptors (mGluR2/3) regulate synaptic strength by inhibiting secretion. Here, we reveal a presynaptic inhibitory pathway activated by extracellular signal-regulated kinase (ERK) that mediates CB1R- and mGluR2/3-induced secretion inhibition. This pathway is triggered by a variety of events, from foot shock-induced stress to intense neuronal activity, and induces phosphorylation of the presynaptic protein Munc18-1. Mimicking constitutive phosphorylation of Munc18-1 results in a drastic decrease in synaptic transmission. ERK-mediated phosphorylation of Munc18-1 ultimately leads to degradation by the ubiquitin-proteasome system. Conversely, preventing ERK-dependent Munc18-1 phosphorylation increases synaptic strength. CB1R- and mGluR2/3-induced synaptic inhibition and depolarization-induced suppression of excitation (DSE) are reduced upon ERK/MEK pathway inhibition and further reduced when ERK-dependent Munc18-1 phosphorylation is blocked. Thus, ERK-dependent Munc18-1 phosphorylation provides a major negative feedback loop to control synaptic strength upon activation of presynaptic receptors and during intense neuronal activity.
Collapse
Affiliation(s)
- Sabine K Schmitz
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Cillian King
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Christian Kortleven
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Vincent Huson
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Tim Kroon
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Josta T Kevenaar
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Desiree Schut
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Ingrid Saarloos
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Joost P Hoetjes
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Heidi de Wit
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Oliver Stiedl
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Sabine Spijker
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Ka Wan Li
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - August B Smit
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Lennart Niels Cornelisse
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Matthijs Verhage
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands
| |
Collapse
|
41
|
The calcium sensor synaptotagmin 7 is required for synaptic facilitation. Nature 2016; 529:88-91. [PMID: 26738595 PMCID: PMC4729191 DOI: 10.1038/nature16507] [Citation(s) in RCA: 204] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 12/03/2015] [Indexed: 11/22/2022]
Abstract
It has been known for over 70 years that synaptic strength is dynamically regulated in a use-dependent manner1. At synapses with a low initial release probability, closely spaced presynaptic action potentials can result in facilitation, a short-term form of enhancement where each subsequent action potential evokes greater neurotransmitter release2. Facilitation can enhance neurotransmitter release manyfold and profoundly influence information transfer across synapses3, but the underlying mechanism remains a mystery. Among the proposed mechanisms is that a specialized calcium sensor for facilitation transiently increases the probability of release2,4 and is distinct from the fast sensors that mediate rapid neurotransmitter release. Yet such a sensor has never been identified, and its very existence has been disputed5,6. Here we show that synaptotagmin 7 (syt7) is a calcium sensor that is required for facilitation at multiple central synapses. In syt7 knockout mice, facilitation is eliminated even though the initial probability of release and presynaptic residual calcium signals are unaltered. Expression of wild-type syt7 in presynaptic neurons restored facilitation, whereas expression of a mutated syt7 with a calcium-insensitive C2A domain did not. By revealing the role of syt7 in synaptic facilitation, these results resolve a longstanding debate about a widespread form of short-term plasticity, and will enable future studies that may lead to a deeper understanding of the functional importance of facilitation.
Collapse
|
42
|
Suzuki E, Kamiya H. PSD-95 regulates synaptic kainate receptors at mouse hippocampal mossy fiber-CA3 synapses. Neurosci Res 2015; 107:14-9. [PMID: 26746114 DOI: 10.1016/j.neures.2015.12.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 12/15/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
Abstract
Kainate-type glutamate receptors (KARs) are the third class of ionotropic glutamate receptors whose activation leads to the unique roles in regulating synaptic transmission and circuit functions. In contrast to AMPA receptors (AMPARs), little is known about the mechanism of synaptic localization of KARs. PSD-95, a major scaffold protein of the postsynaptic density, is a candidate molecule that regulates the synaptic KARs. Although PSD-95 was shown to bind directly to KARs subunits, it has not been tested whether PSD-95 regulates synaptic KARs in intact synapses. Using PSD-95 knockout mice, we directly investigated the role of PSD-95 in the KARs-mediated components of synaptic transmission at hippocampal mossy fiber-CA3 synapse, one of the synapses with the highest density of KARs. Mossy fiber EPSCs consist of AMPA receptor (AMPAR)-mediated fast component and KAR-mediated slower component, and the ratio was significantly reduced in PSD-95 knockout mice. The size of KARs-mediated field EPSP reduced in comparison with the size of the fiber volley. Analysis of KARs-mediated miniature EPSCs also suggested reduced synaptic KARs. All the evidence supports critical roles of PSD-95 in regulating synaptic KARs.
Collapse
Affiliation(s)
- Etsuko Suzuki
- Department of Neurobiology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; Japan Society for the Promotion of Science, Tokyo 102-0083, Japan
| | - Haruyuki Kamiya
- Department of Neurobiology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
| |
Collapse
|
43
|
Martin EA, Muralidhar S, Wang Z, Cervantes DC, Basu R, Taylor MR, Hunter J, Cutforth T, Wilke SA, Ghosh A, Williams ME. The intellectual disability gene Kirrel3 regulates target-specific mossy fiber synapse development in the hippocampus. eLife 2015; 4:e09395. [PMID: 26575286 PMCID: PMC4642954 DOI: 10.7554/elife.09395] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/13/2015] [Indexed: 12/14/2022] Open
Abstract
Synaptic target specificity, whereby neurons make distinct types of synapses with different target cells, is critical for brain function, yet the mechanisms driving it are poorly understood. In this study, we demonstrate Kirrel3 regulates target-specific synapse formation at hippocampal mossy fiber (MF) synapses, which connect dentate granule (DG) neurons to both CA3 and GABAergic neurons. Here, we show Kirrel3 is required for formation of MF filopodia; the structures that give rise to DG-GABA synapses and that regulate feed-forward inhibition of CA3 neurons. Consequently, loss of Kirrel3 robustly increases CA3 neuron activity in developing mice. Alterations in the Kirrel3 gene are repeatedly associated with intellectual disabilities, but the role of Kirrel3 at synapses remained largely unknown. Our findings demonstrate that subtle synaptic changes during development impact circuit function and provide the first insight toward understanding the cellular basis of Kirrel3-dependent neurodevelopmental disorders. DOI:http://dx.doi.org/10.7554/eLife.09395.001 Nerve cells in the brain connect to each other via junctions called synapses to form vast networks that process information. Much like streets can be joined with stop signs, traffic lights, or exit ramps depending on the flow of traffic, different types of synapses control the flow of information along nerves in distinct ways. In a region of the brain called the hippocampus, nerve cells called DG neurons are connected to other neurons by two different types of synapses. One type of synapse allows the DG neurons to activate CA3 neurons, while the second type allows the DG neurons to activate GABAergic neurons. These same GABAergic neurons can then inhibit the activity of the CA3 neurons. Therefore, through these two different types of synapses, DG neurons can both increase and decrease the activity of the CA3 neurons. This delicate balance of activity across the two types of DG synapses is very important for the hippocampus to work properly, which is critical for our ability to learn and remember. Mutations in the gene that encodes a protein called Kirrel3 are associated with autism, Jacobsen's syndrome, and other disorders that affect intellectual ability in humans. Kirrel3 is similar to a protein found in roundworms that regulates the formation of synapses, but it is not known if it plays the same role in humans and other mammals. Now, Martin, Muralidhar et al. studied the role of Kirrel3 in mice. The experiments show that Kirrel3 is produced in both the DG neurons and the GABAergic neurons, but not the CA3 neurons. Young mutant mice that lacked Kirrel3 made fewer synapse-forming structures between DG neurons and GABAergic neurons than normal mice, but the synapses that connect DG neurons to CA3 neurons formed normally. This disrupted the balance of activity across the two types of DG synapses and the CA3 neurons in the mutant mice were over-active. Together, Martin, Muralidhar et al.'s findings show that altering the levels of Kirrel3 can alter the balance of synapses in the hippocampus. This may explain how even very small changes in synapse formation during brain development can have a big impact on nerve cell activity. The next challenge is to understand exactly how Kirrel3 helps build synapses, which may lead to the development of new drugs that help to rebalance brain activity in people that lack Kirrel3. DOI:http://dx.doi.org/10.7554/eLife.09395.002
Collapse
Affiliation(s)
- E Anne Martin
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Shruti Muralidhar
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Zhirong Wang
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Diégo Cordero Cervantes
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Raunak Basu
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Matthew R Taylor
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Jennifer Hunter
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| | - Tyler Cutforth
- Department of Neurology, Columbia University, New York City, United States
| | - Scott A Wilke
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, San Diego, United States
| | - Anirvan Ghosh
- Neuroscience Discovery, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel, Switzerland
| | - Megan E Williams
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, United States
| |
Collapse
|
44
|
Hyun JH, Eom K, Lee KH, Bae JY, Bae YC, Kim MH, Kim S, Ho WK, Lee SH. Kv1.2 mediates heterosynaptic modulation of direct cortical synaptic inputs in CA3 pyramidal cells. J Physiol 2015; 593:3617-43. [PMID: 26047212 DOI: 10.1113/jp270372] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 05/26/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We investigated the cellular mechanisms underlying mossy fibre-induced heterosynaptic long-term potentiation of perforant path (PP) inputs to CA3 pyramidal cells. Here we show that this heterosynaptic potentiation is mediated by downregulation of Kv1.2 channels. The downregulation of Kv1.2 preferentially enhanced PP-evoked EPSPs which occur at distal apical dendrites. Such enhancement of PP-EPSPs required activation of dendritic Na(+) channels, and its threshold was lowered by downregulation of Kv1.2. Our results may provide new insights into the long-standing question of how mossy fibre inputs constrain the CA3 network to sparsely represent direct cortical inputs. ABSTRACT A short high frequency stimulation of mossy fibres (MFs) induces long-term potentiation (LTP) of direct cortical or perforant path (PP) synaptic inputs in hippocampal CA3 pyramidal cells (CA3-PCs). However, the cellular mechanism underlying this heterosynaptic modulation remains elusive. Previously, we reported that repetitive somatic firing at 10 Hz downregulates Kv1.2 in the CA3-PCs. Here, we show that MF inputs induce similar somatic firing and downregulation of Kv1.2 in the CA3-PCs. The effect of Kv1.2 downregulation was specific to PP synaptic inputs that arrive at distal apical dendrites. We found that the somatodendritic expression of Kv1.2 is polarized to distal apical dendrites. Compartmental simulations based on this finding suggested that passive normalization of synaptic inputs and polarized distributions of dendritic ionic channels may facilitate the activation of dendritic Na(+) channels preferentially at distal apical dendrites. Indeed, partial block of dendritic Na(+) channels using 10 nm tetrodotoxin brought back the enhanced PP-evoked excitatory postsynaptic potentials (PP-EPSPs) to the baseline level. These results indicate that activity-dependent downregulation of Kv1.2 in CA3-PCs mediates MF-induced heterosynaptic LTP of PP-EPSPs by facilitating activation of Na(+) channels at distal apical dendrites.
Collapse
Affiliation(s)
- Jung Ho Hyun
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kisang Eom
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kyu-Hee Lee
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Jin Young Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Republic of Korea
| | - Yong Chul Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Republic of Korea
| | - Myoung-Hwan Kim
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Sooyun Kim
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Won-Kyung Ho
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Suk-Ho Lee
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| |
Collapse
|
45
|
Pardi MB, Ogando MB, Schinder AF, Marin-Burgin A. Differential inhibition onto developing and mature granule cells generates high-frequency filters with variable gain. eLife 2015; 4:e08764. [PMID: 26163657 PMCID: PMC4521582 DOI: 10.7554/elife.08764] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 07/10/2015] [Indexed: 11/13/2022] Open
Abstract
Adult hippocampal neurogenesis provides the dentate gyrus with heterogeneous populations of granule cells (GC) originated at different times. The contribution of these cells to information encoding is under current investigation. Here, we show that incoming spike trains activate different populations of GC determined by the stimulation frequency and GC age. Immature GC respond to a wider range of stimulus frequencies, whereas mature GC are less responsive at high frequencies. This difference is dictated by feedforward inhibition, which restricts mature GC activation. Yet, the stronger inhibition of mature GC results in a higher temporal fidelity compared to that of immature GC. Thus, hippocampal inputs activate two populations of neurons with variable frequency filters: immature cells, with wide-range responses, that are reliable transmitters of the incoming frequency, and mature neurons, with narrow frequency response, that are precise at informing the beginning of the stimulus, but with a sparse activity.
Collapse
Affiliation(s)
- María Belén Pardi
- Instituto de Investigación en Biomedicina de Buenos Aires-CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Mora Belén Ogando
- Instituto de Investigación en Biomedicina de Buenos Aires-CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Alejandro F Schinder
- Laboratory of Neuronal Plasticity, Leloir Institute-CONICET, Buenos Aires, Argentina
| | - Antonia Marin-Burgin
- Instituto de Investigación en Biomedicina de Buenos Aires-CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| |
Collapse
|
46
|
Siegert S, Seo J, Kwon EJ, Rudenko A, Cho S, Wang W, Flood Z, Martorell AJ, Ericsson M, Mungenast AE, Tsai LH. The schizophrenia risk gene product miR-137 alters presynaptic plasticity. Nat Neurosci 2015; 18:1008-16. [PMID: 26005852 PMCID: PMC4506960 DOI: 10.1038/nn.4023] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/24/2015] [Indexed: 12/14/2022]
Abstract
Noncoding variants in the human MIR137 gene locus increase schizophrenia risk with genome-wide significance. However, the functional consequence of these risk alleles is unknown. Here we examined induced human neurons harboring the minor alleles of four disease-associated single nucleotide polymorphisms in MIR137. We observed increased MIR137 levels compared to those in major allele-carrying cells. microRNA-137 gain of function caused downregulation of the presynaptic target genes complexin-1 (Cplx1), Nsf and synaptotagmin-1 (Syt1), leading to impaired vesicle release. In vivo, miR-137 gain of function resulted in changes in synaptic vesicle pool distribution, impaired induction of mossy fiber long-term potentiation and deficits in hippocampus-dependent learning and memory. By sequestering endogenous miR-137, we were able to ameliorate the synaptic phenotypes. Moreover, reinstatement of Syt1 expression partially restored synaptic plasticity, demonstrating the importance of Syt1 as a miR-137 target. Our data provide new insight into the mechanism by which miR-137 dysregulation can impair synaptic plasticity in the hippocampus.
Collapse
Affiliation(s)
- Sandra Siegert
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Jinsoo Seo
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Ester J. Kwon
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Andrii Rudenko
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Sukhee Cho
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Wenyuan Wang
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Zachary Flood
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Anthony J. Martorell
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Maria Ericsson
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alison E. Mungenast
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| |
Collapse
|
47
|
mGlu5 acts as a switch for opposing forms of synaptic plasticity at mossy fiber-CA3 and commissural associational-CA3 synapses. J Neurosci 2015; 35:4999-5006. [PMID: 25810529 DOI: 10.1523/jneurosci.3417-14.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Within the hippocampus, different kinds of spatial experience determine the direction of change of synaptic weights. Synaptic plasticity resulting from such experience may enable memory encoding. The CA3 region is very striking in this regard: due to the distinct molecular properties of the mossy fiber (MF) and associational-commissural (AC) synapses, it is believed that they enable working memory and pattern completion. The question arises, however, as to how information reaching these synapses results in differentiated encoding. Given its crucial role in enabling persistent synaptic plasticity in other hippocampal subfields, we speculated that the metabotropic glutamate receptor mGlu5 may regulate information encoding at MF and AC synapses. Here, we show that antagonism of mGlu5 inhibits LTP, but not LTD at MF synapses of freely behaving adult rats. Conversely, mGlu5 antagonism prevents LTD but not LTP at AC-CA3 synapses. This suggests that, under conditions in which mGlu5 is activated, LTP may be preferentially induced at MF synapses, whereas LTD is favored at AC synapses. To assess this possibility, we applied 50 Hz stimulation that should generate postsynaptic activity that corresponds to θm, the activation threshold that lies between LTP and LTD. MGlu5 activation had no effect on AC responses but potentiated MF synapses. These data suggest that mGlu5 serves as a switch that alters signal-to-noise ratios during information encoding in the CA3 region. This mechanism supports highly tuned and differentiated information storage in CA3 synapses.
Collapse
|
48
|
Trieu BH, Kramár EA, Cox CD, Jia Y, Wang W, Gall CM, Lynch G. Pronounced differences in signal processing and synaptic plasticity between piriform-hippocampal network stages: a prominent role for adenosine. J Physiol 2015; 593:2889-907. [PMID: 25902928 DOI: 10.1113/jp270398] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/17/2015] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Extended trains of theta rhythm afferent activity lead to a biphasic response facilitation in field CA1 but not in the lateral perforant path input to the dentate gyrus. Processes that reverse long-term potentiation in field CA1 are not operative in the lateral perforant path: multiple lines of evidence indicate that this reflects differences in adenosine signalling. Adenosine A1 receptors modulate baseline synaptic transmission in the lateral olfactory tract but not the associational afferents of the piriform cortex. Levels of ecto-5'-nucleotidase (CD73), an enzyme that converts extracellular ATP into adenosine, are markedly different between regions and correlate with adenosine signalling and the efficacy of theta pulse stimulation in reversing long-term potentiation. Variations in transmitter mobilization, CD73 levels, and afferent divergence result in multivariate differences in signal processing through nodes in the cortico-hippocampal network. ABSTRACT The present study evaluated learning-related synaptic operations across the serial stages of the olfactory cortex-hippocampus network. Theta frequency stimulation produced very different time-varying responses in the Schaffer-commissural projections than in the lateral perforant path (LPP), an effect associated with distinctions in transmitter mobilization. Long-term potentiation (LTP) had a higher threshold in LPP field potential studies but not in voltage clamped neurons; coupled with input/output relationships, these results suggest that LTP threshold differences reflect the degree of input divergence. Theta pulse stimulation erased LTP in CA1 but not in the dentate gyrus (DG), although adenosine eliminated potentiation in both areas, suggesting that theta increases extracellular adenosine to a greater degree in CA1. Moreover, adenosine A1 receptor antagonism had larger effects on theta responses in CA1 than in the DG, and concentrations of ecto-5'-nucleotidase (CD73) were much higher in CA1. Input/output curves for two connections in the piriform cortex were similar to those for the LPP, whereas adenosine modulation again correlated with levels of CD73. In sum, multiple relays in a network extending from the piriform cortex through the hippocampus can be differentiated along three dimensions (input divergence, transmitter mobilization, adenosine modulation) that potently influence throughput and plasticity. A model that incorporates the regional differences, supplemented with data for three additional links, suggests that network output goes through three transitions during the processing of theta input. It is proposed that individuated relays allow the circuit to deal with different types of behavioural problems.
Collapse
Affiliation(s)
- Brian H Trieu
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Enikö A Kramár
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - Conor D Cox
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Yousheng Jia
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Weisheng Wang
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Christine M Gall
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA.,Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA.,Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA
| |
Collapse
|
49
|
Wallis JL, Irvine MW, Jane DE, Lodge D, Collingridge GL, Bortolotto ZA. An interchangeable role for kainate and metabotropic glutamate receptors in the induction of rat hippocampal mossy fiber long-term potentiation in vivo. Hippocampus 2015; 25:1407-17. [PMID: 25821051 PMCID: PMC4707721 DOI: 10.1002/hipo.22460] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2015] [Indexed: 12/31/2022]
Abstract
The roles of both kainate receptors (KARs) and metabotropic glutamate receptors (mGluRs) in mossy fiber long-term potentiation (MF-LTP) have been extensively studied in hippocampal brain slices, but the findings are controversial. In this study, we have addressed the roles of both mGluRs and KARs in MF-LTP in anesthetized rats. We found that MF-LTP could be induced in the presence of either GluK1-selective KAR antagonists or group I mGluR antagonists. However, LTP was inhibited when the group I mGluRs and the GluK1-KARs were simultaneously inhibited. Either mGlu1 or mGlu5 receptor activation is sufficient to induce this form of LTP as selective inhibition of either subtype alone, together with the inhibition of KARs, did not inhibit MF-LTP. These data suggest that mGlu1 receptors, mGlu5 receptors, and GluK1-KARs are all engaged during high-frequency stimulation, and that the activation of any one of these receptors alone is sufficient for the induction of MF-LTP in vivo.
Collapse
Affiliation(s)
- James L Wallis
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Mark W Irvine
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - David E Jane
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - David Lodge
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Graham L Collingridge
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Zuner A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| |
Collapse
|
50
|
Galván EJ, Pérez-Rosello T, Gómez-Lira G, Lara E, Gutiérrez R, Barrionuevo G. Synapse-specific compartmentalization of signaling cascades for LTP induction in CA3 interneurons. Neuroscience 2015; 290:332-45. [PMID: 25637803 DOI: 10.1016/j.neuroscience.2015.01.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/15/2015] [Accepted: 01/15/2015] [Indexed: 11/28/2022]
Abstract
Inhibitory interneurons with somata in strata radiatum and lacunosum-molecular (SR/L-M) of hippocampal area CA3 receive excitatory input from pyramidal cells via the recurrent collaterals (RCs), and the dentate gyrus granule cells via the mossy fibers (MFs). Here we demonstrate that Hebbian long-term potentiation (LTP) at RC synapses on SR/L-M interneurons requires the concomitant activation of calcium-impermeable AMPARs (CI-AMPARs) and N-methyl-d-aspartate receptors (NMDARs). RC LTP was prevented by voltage clamping the postsynaptic cell during high-frequency stimulation (HFS; 3 trains of 100 pulses delivered at 100 Hz every 10s), with intracellular injections of the Ca(2+) chelator BAPTA (20mM), and with the NMDAR antagonist D-AP5. In separate experiments, RC and MF inputs converging onto the same interneuron were sequentially activated. We found that RC LTP induction was blocked by inhibitors of the calcium/calmodulin-dependent protein kinase II (CaMKII; KN-62, 10 μM or KN-93, 10 μM) but MF LTP was CaMKII independent. Conversely, the application of the protein kinase A (PKA) activators forskolin/IBMX (50 μM/25 μM) potentiated MF EPSPs but not RC EPSPs. Together these data indicate that the aspiny dendrites of SR/L-M interneurons compartmentalize synapse-specific Ca(2+) signaling required for LTP induction at RC and MF synapses. We also show that the two signal transduction cascades converge to activate a common effector, protein kinase C (PKC). Specifically, LTP at RC and MF synapses on the same SR/LM interneuron was blocked by postsynaptic injections of chelerythrine (10 μM). These data indicate that both forms of LTP share a common mechanism involving PKC-dependent signaling modulation.
Collapse
Affiliation(s)
- E J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico.
| | - T Pérez-Rosello
- Department of Physiology, Northwestern University, Chicago, IL, USA
| | - G Gómez-Lira
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico
| | - E Lara
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico
| | - R Gutiérrez
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico
| | - G Barrionuevo
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| |
Collapse
|