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Neuronal Activity-Dependent Activation of Astroglial Calcineurin in Mouse Primary Hippocampal Cultures. Int J Mol Sci 2018; 19:ijms19102997. [PMID: 30274399 PMCID: PMC6213389 DOI: 10.3390/ijms19102997] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/25/2018] [Accepted: 09/29/2018] [Indexed: 12/11/2022] Open
Abstract
Astrocytes respond to neuronal activity by generating calcium signals which are implicated in the regulation of astroglial housekeeping functions and/or in modulation of synaptic transmission. We hypothesized that activity-induced calcium signals in astrocytes may activate calcineurin (CaN), a calcium/calmodulin-regulated protein phosphatase, implicated in neuropathology, but whose role in astroglial physiology remains unclear. We used a lentiviral vector expressing NFAT-EYFP (NY) fluorescent calcineurin sensor and a chemical protocol of LTP induction (cLTP) to show that, in mixed neuron-astrocytic hippocampal cultures, cLTP induced robust NY translocation into astrocyte nuclei and, hence, CaN activation. NY translocation was abolished by the CaN inhibitor FK506, and was not observed in pure astroglial cultures. Using Fura-2 single cell calcium imaging, we found sustained Ca2+ elevations in juxtaneuronal, but not distal, astrocytes. Pharmacological analysis revealed that both the Ca2+ signals and the nuclear NY translocation in astrocytes required NMDA and mGluR5 receptors and depended on extracellular Ca2+ entry via a store-operated mechanism. Our results provide a proof of principle that calcineurin in astrocytes may be activated in response to neuronal activity, thereby delineating a framework for investigating the role of astroglial CaN in the physiology of central nervous system.
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Yan BC, Jeon YH, Park JH, Kim IH, Cho JH, Ahn JH, Chen BH, Tae HJ, Lee JC, Ahn JY, Kim DW, Cho JH, Won MH, Hong S. Increased cyclooxygenase-2 and nuclear factor-κB/p65 expression in mouse hippocampi after systemic administration of tetanus toxin. Mol Med Rep 2015; 12:7837-44. [PMID: 26498481 PMCID: PMC4758276 DOI: 10.3892/mmr.2015.4490] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 10/01/2015] [Indexed: 12/21/2022] Open
Abstract
Brain inflammation has a crucial role in various diseases of the central nervous system. The hippocampus in the mammalian brain exerts an important memory function, which is sensitive to various insults, including inflammation induced by exo/endotoxin stimuli. Tetanus toxin (TeT) is an exotoxin with the capacity for neuronal binding and internalization. The present study investigated changes in inflammatory mediators in the mouse hippocampus proper (CA1‑3 regions) and dentate gyrus (DG) after TeT treatment. The experimental mice were intraperitoneally injected with TeT at a low dosage (100 ng/kg), while the control mice were injected with the same volume of saline. At 6, 12 and 24 h after TeT treatment, changes in the hippocampal levels of inflammatory mediators cyclooxygenase‑2 (COX‑2) and nuclear factor kappa‑B (NF‑κB/p65) were assessed using immunohistochemical and western blot analysis. In the control group, moderate COX‑2 immunoreactivity was observed in the stratum pyramidal (SP) of the CA2‑3 region, while almost no expression was identified in the CA1 region and the DG. COX‑2 immunoreactivity was increased by TeT in the SP and granule cell layer (GCL) of the DG in a time‑dependent manner. At 24 h post‑treatment, COX‑2 immunoreactivity in the SP of the CA1 region and in the GCL of the DG was high, and COX‑2 immunoreactivity in the SP of the CA2/3 region was highest. Furthermore, the present study observed that NF‑κB/p65 immunoreactivity was obviously increased in the SP and GCL at 6, 12 and 24 h after TeT treatment. In conclusion, the present study demonstrated that systemic treatment with TeT significantly increased the expression of COX-2 and NF-κB/p65 in the mouse hippocampus, suggesting that increased COX‑2 and NF-κB/65 expression may be associated with inflammation in the brain induced by exotoxins.
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Affiliation(s)
- Bing Chun Yan
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, Jiangsu 225001, P.R. China
| | - Yong Hwan Jeon
- Department of Radiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Joon Ha Park
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - In Hye Kim
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Jeong-Hwi Cho
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Ji Hyeon Ahn
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Bai Hui Chen
- Department of Physiology, College of Medicine, Hallym University, Chuncheon, Gangwon 200‑702, Republic of Korea
| | - Hyun-Jin Tae
- Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 200‑702, Republic of Korea
| | - Jae-Chul Lee
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Ji Yun Ahn
- Department of Emergency Medicine, Sacred Heart Hospital, College of Medicine, Hallym University, Anyang, Gyeonggi 431‑796, Republic of Korea
| | - Dong Won Kim
- Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Jun Hwi Cho
- Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Moo-Ho Won
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
| | - Seongkweon Hong
- Department of Surgery, School of Medicine, Kangwon National University, Chuncheon, Gangwon 200‑701, Republic of Korea
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Hussain S, Davanger S. Postsynaptic VAMP/Synaptobrevin Facilitates Differential Vesicle Trafficking of GluA1 and GluA2 AMPA Receptor Subunits. PLoS One 2015; 10:e0140868. [PMID: 26488171 PMCID: PMC4619507 DOI: 10.1371/journal.pone.0140868] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 10/01/2015] [Indexed: 12/03/2022] Open
Abstract
Vertebrate organisms adapt to a continuously changing environment by regulating the strength of synaptic connections between brain cells. Excitatory synapses are believed to increase their strength by vesicular insertion of transmitter glutamate receptors into the postsynaptic plasma membrane. These vesicles, however, have never been demonstrated or characterized. For the first time, we show the presence of small vesicles in postsynaptic spines, often closely adjacent to the plasma membrane and PSD (postsynaptic density). We demonstrate that they harbor vesicle-associated membrane protein 2 (VAMP2/synaptobrevin-2) and glutamate receptor subunit 1 (GluA1). Disrupting VAMP2 by tetanus toxin treatment reduces the concentration of GluA1 in the postsynaptic plasma membrane. GluA1/VAMP2-containing vesicles, but not GluA2/VAMP2-vesicles, are concentrated in postsynaptic spines relative to dendrites. Our results indicate that small postsynaptic vesicles containing GluA1 are inserted directly into the spine plasma membrane through a VAMP2-dependent mechanism.
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Affiliation(s)
- Suleman Hussain
- Laboratory for Synaptic Plasticity, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Science, University of Oslo, P.O. Box 1105 Blindern, 0317 Oslo, Norway
| | - Svend Davanger
- Laboratory for Synaptic Plasticity, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Science, University of Oslo, P.O. Box 1105 Blindern, 0317 Oslo, Norway
- * E-mail:
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Liotta A, Çalışkan G, ul Haq R, Hollnagel JO, Rösler A, Heinemann U, Behrens CJ. Partial Disinhibition Is Required for Transition of Stimulus-Induced Sharp Wave–Ripple Complexes Into Recurrent Epileptiform Discharges in Rat Hippocampal Slices. J Neurophysiol 2011; 105:172-87. [DOI: 10.1152/jn.00186.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sharp wave–ripple complexes (SPW-Rs) in the intact rodent hippocampus are characterized by slow field potential transients superimposed by close to 200-Hz ripple oscillations. Similar events have been recorded in hippocampal slices where SPW-Rs occur spontaneously or can be induced by repeated application of high-frequency stimulation, a standard protocol for induction of long-lasting long-term potentiation. Such stimulation is reminiscent of protocols used to induce kindling epilepsy and ripple oscillations may be predictive of the epileptogenic zone in temporal lobe epilepsy. In the present study, we investigated the relation between recurrent epileptiform discharges (REDs) and SPW-Rs by studying effects of partial removal of inhibition. In particular, we compared the effects of nicotine, low-dose bicuculline methiodide (BMI), and elevated extracellular potassium concentration ([K+]o) on induced SPW-Rs. We show that nicotine dose-dependently transformed SPW-Rs into REDs. This transition was associated with reduced inhibitory conductance in CA3 pyramidal cells. Similar results were obtained from slices where the GABAergic conductance was reduced by application of low concentrations of BMI (1–2 μM). In contrast, sharp waves were diminished by phenobarbital. Elevating [K+]o from 3 to 8.5 mM did not transform SPW-Rs into REDs but significantly increased their incidence and amplitude. Under these conditions, the equilibrium potential for inhibition was shifted in depolarizing direction, whereas inhibitory conductance was significantly increased. Interestingly, the propensity of elevated [K+]o to induce seizure-like events was reduced in slices where SPW-Rs had been induced. In conclusion, recruitment of inhibitory cells during SPW-Rs may serve as a mechanism by which hyperexcitation and eventually seizure generation might be prevented.
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Affiliation(s)
- Agustin Liotta
- Institute of Neurophysiology, Institute for Physiology and
| | | | - Rizwan ul Haq
- Institute of Neurophysiology, Institute for Physiology and
| | | | - Anton Rösler
- Institute of Neurophysiology, Institute for Physiology and
| | - Uwe Heinemann
- Institute of Neurophysiology, Institute for Physiology and
- NeuroCure Research Center, Charité–Universitätsmedizin Berlin, Berlin, Germany
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Jenstad M, Quazi AZ, Zilberter M, Haglerød C, Berghuis P, Saddique N, Goiny M, Buntup D, Davanger S, S Haug FM, Barnes CA, McNaughton BL, Ottersen OP, Storm-Mathisen J, Harkany T, Chaudhry FA. System A transporter SAT2 mediates replenishment of dendritic glutamate pools controlling retrograde signaling by glutamate. ACTA ACUST UNITED AC 2008; 19:1092-106. [PMID: 18832333 DOI: 10.1093/cercor/bhn151] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Glutamate mediates several modes of neurotransmission in the central nervous system including recently discovered retrograde signaling from neuronal dendrites. We have previously identified the system N transporter SN1 as being responsible for glutamine efflux from astroglia and proposed a system A transporter (SAT) in subsequent transport of glutamine into neurons for neurotransmitter regeneration. Here, we demonstrate that SAT2 expression is primarily confined to glutamatergic neurons in many brain regions with SAT2 being predominantly targeted to the somatodendritic compartments in these neurons. SAT2 containing dendrites accumulate high levels of glutamine. Upon electrical stimulation in vivo and depolarization in vitro, glutamine is readily converted to glutamate in activated dendritic subsegments, suggesting that glutamine sustains release of the excitatory neurotransmitter via exocytosis from dendrites. The system A inhibitor MeAIB (alpha-methylamino-iso-butyric acid) reduces neuronal uptake of glutamine with concomitant reduction in intracellular glutamate concentrations, indicating that SAT2-mediated glutamine uptake can be a prerequisite for the formation of glutamate. Furthermore, MeAIB inhibited retrograde signaling from pyramidal cells in layer 2/3 of the neocortex by suppressing inhibitory inputs from fast-spiking interneurons. In summary, we demonstrate that SAT2 maintains a key metabolic glutamine/glutamate balance underpinning retrograde signaling by dendritic release of the neurotransmitter glutamate.
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Affiliation(s)
- Monica Jenstad
- The Biotechnology Centre of Oslo, University of Oslo, N-0317 Oslo, Norway
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