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Xing B, Barbour AJ, Vithayathil J, Li X, Dutko S, Fawcett-Patel J, Lancaster E, Talos DM, Jensen FE. Reversible synaptic adaptations in a subpopulation of murine hippocampal neurons following early-life seizures. J Clin Invest 2024; 134:e175167. [PMID: 38227384 PMCID: PMC10904056 DOI: 10.1172/jci175167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 01/11/2024] [Indexed: 01/17/2024] Open
Abstract
Early-life seizures (ELSs) can cause permanent cognitive deficits and network hyperexcitability, but it is unclear whether ELSs induce persistent changes in specific neuronal populations and whether these changes can be targeted to mitigate network dysfunction. We used the targeted recombination of activated populations (TRAP) approach to genetically label neurons activated by kainate-induced ELSs in immature mice. The ELS-TRAPed neurons were mainly found in hippocampal CA1, remained uniquely susceptible to reactivation by later-life seizures, and displayed sustained enhancement in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated (AMPAR-mediated) excitatory synaptic transmission and inward rectification. ELS-TRAPed neurons, but not non-TRAPed surrounding neurons, exhibited enduring decreases in Gria2 mRNA, responsible for encoding the GluA2 subunit of the AMPARs. This was paralleled by decreased synaptic GluA2 protein expression and heightened phosphorylated GluA2 at Ser880 in dendrites, indicative of GluA2 internalization. Consistent with increased GluA2-lacking AMPARs, ELS-TRAPed neurons showed premature silent synapse depletion, impaired long-term potentiation, and impaired long-term depression. In vivo postseizure treatment with IEM-1460, an inhibitor of GluA2-lacking AMPARs, markedly mitigated ELS-induced changes in TRAPed neurons. These findings show that enduring modifications of AMPARs occur in a subpopulation of ELS-activated neurons, contributing to synaptic dysplasticity and network hyperexcitability, but are reversible with early IEM-1460 intervention.
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2
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Zhang C, Ni C, Lu H. Polo-Like Kinase 2: From Principle to Practice. Front Oncol 2022; 12:956225. [PMID: 35898867 PMCID: PMC9309260 DOI: 10.3389/fonc.2022.956225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/14/2022] [Indexed: 11/21/2022] Open
Abstract
Polo-like kinase (PLK) 2 is an evolutionarily conserved serine/threonine kinase that shares the n-terminal kinase catalytic domain and the C-terminal Polo Box Domain (PBD) with other members of the PLKs family. In the last two decades, mounting studies have focused on this and tried to clarify its role in many aspects. PLK2 is essential for mitotic centriole replication and meiotic chromatin pairing, synapsis, and crossing-over in the cell cycle; Loss of PLK2 function results in cell cycle disorders and developmental retardation. PLK2 is also involved in regulating cell differentiation and maintaining neural homeostasis. In the process of various stimuli-induced stress, including oxidative and endoplasmic reticulum, PLK2 may promote survival or apoptosis depending on the intensity of stimulation and the degree of cell damage. However, the role of PLK2 in immunity to viral infection has been studied far less than that of other family members. Because PLK2 is extensively and deeply involved in normal physiological functions and pathophysiological mechanisms of cells, its role in diseases is increasingly being paid attention to. The effect of PLK2 in inhibiting hematological tumors and fibrotic diseases, as well as participating in neurodegenerative diseases, has been gradually recognized. However, the research results in solid organ tumors show contradictory results. In addition, preliminary studies using PLK2 as a disease predictor and therapeutic target have yielded some exciting and promising results. More research will help people better understand PLK2 from principle to practice.
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Affiliation(s)
- Chuanyong Zhang
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
| | - Chuangye Ni
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
| | - Hao Lu
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
- *Correspondence: Hao Lu,
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3
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Chancey JH, Howard MA. Synaptic Integration in CA1 Pyramidal Neurons Is Intact despite Deficits in GABAergic Transmission in the Scn1a Haploinsufficiency Mouse Model of Dravet Syndrome. eNeuro 2022; 9:ENEURO.0080-22.2022. [PMID: 35523580 PMCID: PMC9116933 DOI: 10.1523/eneuro.0080-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/29/2022] [Accepted: 04/27/2022] [Indexed: 01/13/2023] Open
Abstract
Mutations of SCN1A, which encodes the voltage-gated sodium channel Nav1.1, can cause epilepsy disorders such as Dravet syndrome (DS) that are comorbid with wide-ranging neurologic dysfunction. Many studies suggest that Nav1.1 haploinsufficiency causes forebrain GABAergic interneuron hypoexcitability, while pyramidal neuron physiology is mostly unaltered, and that this serves as a primary cell physiology phenotype linking mutation to disease. We hypothesized that deficits in inhibition would alter synaptic integration during activation of the hippocampal microcircuit, thus disrupting cellular information processing and leading to seizures and cognitive deficits. We tested this hypothesis using ex vivo whole-cell recordings from CA1 pyramidal neurons in a heterozygous Scn1a knock-out mouse model and wild-type (WT) littermates, measuring responses to single and patterned synaptic stimulation and spontaneous synaptic activity. Overall, our experiments reveal a surprising normalcy of excitatory and inhibitory synaptic temporal integration in the hippocampus of Scn1a haploinsufficient mice. While miniature IPSCs and feedforward inhibition and were decreased, we did not identify a pattern or frequency of input that caused a failure of synaptic inhibition. We further show that reduced GABA release probability and subsequent reduced short-term depression may act to overcome deficits in inhibition normalizing input/output functions in the Scn1a haploinsufficient hippocampus. These experiments show that CA1 pyramidal neuron synaptic processing is surprisingly robust, even during decreased interneuron function, and more complex circuit activity is likely required to reveal altered function in the hippocampal microcircuit.
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Affiliation(s)
- Jessica Hotard Chancey
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
| | - MacKenzie Allen Howard
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
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4
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Lippman-Bell JJ, Handy M, Nieder CG, Getzfread M, Jensen FE. Altered hippocampal dendritic spine maturation after hypoxia-induced seizures in neonatal rats. Mol Cell Neurosci 2021; 113:103629. [PMID: 34015497 DOI: 10.1016/j.mcn.2021.103629] [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: 10/01/2020] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 12/01/2022] Open
Abstract
Cognitive comorbidities often follow early-life seizures (ELS), especially in the setting of autism and other neurodevelopmental syndromes. However, there is an incomplete understanding of whether neuronal and synaptic development are concomitantly dysregulated. We have previously shown that hypoxia-induced seizures (HS) in postnatal day (P)10 rats increase acute and later-life hippocampal glutamatergic neurotransmission and spontaneous recurrent seizures, and impair cognition and behavior. As dendritic spines critically regulate synaptic function, we hypothesized that ELS can induce developmentally specific changes in dendritic spine maturation. At intervals during one month following HS in P10 rats, we assessed dendritic spine development on pyramidal neurons in the stratum radiatum of hippocampal area CA1. Compared to control rats in which spine density significantly decreased from P10 to early adulthood (P38), post-seizure rats failed to show a developmental decrease in spine density, and spines from P38 post-seizure rats appeared more immature-shaped (long, thin). In addition, compared to P38 control rats, post-seizure P38 rats expressed significantly more synaptic PSD-95, a marker of mature synapses. These changes were preceded by a transient increase in hippocampal expression of cofilin phosphorylated at Ser3, representing a decrease in cofilin activity. These results suggest that early-life seizures may impair normal dendritic spine maturation and pruning in CA1 during development, resulting in an excess of less efficient synapses, via activity-dependent modification of actin-regulating proteins such as cofilin. Given that multiple neurodevelopmental disorders show similar failures in developmental spine pruning, the current findings may represent a deficit in structural plasticity that could be a component of a mechanism leading to later-life cognitive consequences associated with early-life seizures.
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Affiliation(s)
- Jocelyn J Lippman-Bell
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States of America; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America.
| | - Marcus Handy
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Cassidy G Nieder
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States of America
| | - Mollie Getzfread
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States of America
| | - Frances E Jensen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America.
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5
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Kim S, Yoon I, Son J, Park J, Kim K, Lee JH, Park SY, Kang BS, Han JM, Hwang KY, Kim S. Leucine-sensing mechanism of leucyl-tRNA synthetase 1 for mTORC1 activation. Cell Rep 2021; 35:109031. [PMID: 33910001 DOI: 10.1016/j.celrep.2021.109031] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 12/18/2020] [Accepted: 04/02/2021] [Indexed: 01/07/2023] Open
Abstract
Leucyl-tRNA synthetase 1 (LARS1) mediates activation of leucine-dependent mechanistic target of rapamycin complex 1 (mTORC1) as well as ligation of leucine to its cognate tRNAs, yet its mechanism of leucine sensing is poorly understood. Here we describe leucine binding-induced conformational changes of LARS1. We determine different crystal structures of LARS1 complexed with leucine, ATP, and a reaction intermediate analog, leucyl-sulfamoyl-adenylate (Leu-AMS), and find two distinct functional states of LARS1 for mTORC1 activation. Upon leucine binding to the synthetic site, H251 and R517 in the connective polypeptide and 50FPYPY54 in the catalytic domain change the hydrogen bond network, leading to conformational change in the C-terminal domain, correlating with RagD association. Leucine binding to LARS1 is increased in the presence of ATP, further augmenting leucine-dependent interaction of LARS1 and RagD. Thus, this work unveils the structural basis for leucine-dependent long-range communication between the catalytic and RagD-binding domains of LARS1 for mTORC1 activation.
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Affiliation(s)
- Sulhee Kim
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Ina Yoon
- Medicinal Bioconvergence Research Center, Institute for Artificial Intelligence and Biomedical Research, College of Pharmacy & College of Medicine, Gangnam Severance Hospital, Yonsei University, Incheon 21983, Republic of Korea
| | - Jonghyeon Son
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Junga Park
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Kibum Kim
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon 21983, Republic of Korea; Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Republic of Korea
| | - Ji-Ho Lee
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Sam-Yong Park
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama 230-0045, Japan
| | - Beom Sik Kang
- School of Life Science and Biotechnology, KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jung Min Han
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon 21983, Republic of Korea; Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Republic of Korea
| | - Kwang Yeon Hwang
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea.
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, Institute for Artificial Intelligence and Biomedical Research, College of Pharmacy & College of Medicine, Gangnam Severance Hospital, Yonsei University, Incheon 21983, Republic of Korea.
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6
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Raab CA, Raab M, Becker S, Strebhardt K. Non-mitotic functions of polo-like kinases in cancer cells. Biochim Biophys Acta Rev Cancer 2021; 1875:188467. [PMID: 33171265 DOI: 10.1016/j.bbcan.2020.188467] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022]
Abstract
Inhibitors of mitotic protein kinases are currently being developed as non-neurotoxic alternatives of microtubule-targeting agents (taxanes, vinca alkaloids) which provide a substantial survival benefit for patients afflicted with different types of solid tumors. Among the mitotic kinases, the cyclin-dependent kinases, the Aurora kinases, the kinesin spindle protein and Polo-like kinases (PLKs) have emerged as attractive targets of cancer therapeutics. The functions of mammalian PLK1-5 are traditionally linked to the regulation of the cell cycle and to the stress response. Especially the key role of PLK1 and PLK4 in cellular growth and proliferation, their overexpression in multiple types of human cancer and their druggability, make them appealing targets for cancer therapy. Inhibitors for PLK1 and PLK4 are currently being tested in multiple cancer trials. The clinical success of microtubule-targeting agents is attributed not solely to the induction of a mitotic arrest in cancer cells, but also to non-mitotic effects like targeting intracellular trafficking on microtubules. This raises the question whether new cancer targets like PLK1 and PLK4 regulate critical non-mitotic functions in tumor cells. In this article we summarize the important roles of PLK1-5 for the regulation of non-mitotic signaling. Due to these functions it is conceivable that inhibitors for PLK1 or PLK4 can target interphase cells, which underscores their attractive potential as cancer drug targets. Moreover, we also describe the contribution of the tumor-suppressors PLK2, PLK3 and PLK5 to cancer cell signaling outside of mitosis. These observations highlight the urgent need to develop highly specific ATP-competitive inhibitors for PLK4 and for PLK1 like the 3rd generation PLK-inhibitor Onvansertib to prevent the inhibition of tumor-suppressor PLKs in- and outside of mitosis. The remarkable feature of PLKs to encompass a unique druggable domain, the polo-box-domain (PBD) that can be found only in PLKs offers the opportunity for the development of inhibitors that target PLKs exclusively. Beyond the development of mono-specific ATP-competitive PLK inhibitors, the PBD as drug target will support the design of new drugs that eradicate cancer cells based on the mitotic and non-mitotic function of PLK1 and PLK4.
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Affiliation(s)
| | - Monika Raab
- Department of Gynecology, Goethe-University, Frankfurt, Germany
| | - Sven Becker
- Department of Gynecology, Goethe-University, Frankfurt, Germany
| | - Klaus Strebhardt
- Department of Gynecology, Goethe-University, Frankfurt, Germany; German Cancer Consortium (DKTK), German Cancer Research Center, Partner Site Frankfurt am Main, Frankfurt, Germany.
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7
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LaSarge CL, Pun RYK, Gu Z, Riccetti MR, Namboodiri DV, Tiwari D, Gross C, Danzer SC. mTOR-driven neural circuit changes initiate an epileptogenic cascade. Prog Neurobiol 2020; 200:101974. [PMID: 33309800 DOI: 10.1016/j.pneurobio.2020.101974] [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: 07/06/2020] [Revised: 10/22/2020] [Accepted: 12/05/2020] [Indexed: 11/29/2022]
Abstract
Mutations in genes regulating mTOR pathway signaling are now recognized as a significant cause of epilepsy. Interestingly, these mTORopathies are often caused by somatic mutations, affecting variable numbers of neurons. To better understand how this variability affects disease phenotype, we developed a mouse model in which the mTOR pathway inhibitor Pten can be deleted from 0 to 40 % of hippocampal granule cells. In vivo, low numbers of knockout cells caused focal seizures, while higher numbers led to generalized seizures. Generalized seizures coincided with the loss of local circuit interneurons. In hippocampal slices, low knockout cell loads produced abrupt reductions in population spike threshold, while spontaneous excitatory postsynaptic currents and circuit level recurrent activity increased gradually with rising knockout cell load. Findings demonstrate that knockout cells load is a critical variable regulating disease phenotype, progressing from subclinical circuit abnormalities to electrobehavioral seizures with secondary involvement of downstream neuronal populations.
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Affiliation(s)
- Candi L LaSarge
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Center for Pediatric Neuroscience, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Raymund Y K Pun
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Center for Pediatric Neuroscience, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Zhiqing Gu
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Shanghai Children's Hospital, Shanghai, 200062, China
| | - Matthew R Riccetti
- Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Devi V Namboodiri
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Durgesh Tiwari
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Christina Gross
- Center for Pediatric Neuroscience, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Center for Pediatric Neuroscience, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States; Department of Anesthesia, University of Cincinnati, Cincinnati, OH, 45267, United States.
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8
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Zhang CQ, Catron MA, Ding L, Hanna CM, Gallagher MJ, Macdonald RL, Zhou C. Impaired State-Dependent Potentiation of GABAergic Synaptic Currents Triggers Seizures in a Genetic Generalized Epilepsy Model. Cereb Cortex 2020; 31:768-784. [PMID: 32930324 DOI: 10.1093/cercor/bhaa256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 11/14/2022] Open
Abstract
Epileptic activity in genetic generalized epilepsy (GGE) patients preferentially appears during sleep and its mechanism remains unknown. Here, we found that sleep-like slow-wave oscillations (0.5 Hz SWOs) potentiated excitatory and inhibitory synaptic currents in layer V cortical pyramidal neurons from wild-type (wt) mouse brain slices. In contrast, SWOs potentiated excitatory, but not inhibitory, currents in cortical neurons from a heterozygous (het) knock-in (KI) Gabrg2+Q/390X model of Dravet epilepsy syndrome. This created an imbalance between evoked excitatory and inhibitory currents to effectively prompt neuronal action potential firings. Similarly, physiologically similar up-/down-state induction (present during slow-wave sleep) in cortical neurons also potentiated excitatory synaptic currents within brain slices from wt and het KI mice. Moreover, this state-dependent potentiation of excitatory synaptic currents entailed some signaling pathways of homeostatic synaptic plasticity. Consequently, in het KI mice, in vivo SWO induction (using optogenetic methods) triggered generalized epileptic spike-wave discharges (SWDs), being accompanied by sudden immobility, facial myoclonus, and vibrissa twitching. In contrast, in wt littermates, SWO induction did not cause epileptic SWDs and motor behaviors. To our knowledge, this is the first mechanism to explain why epileptic SWDs preferentially happen during non rapid eye-movement sleep and quiet-wakefulness in human GGE patients.
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Affiliation(s)
- Chun-Qing Zhang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Mackenzie A Catron
- Department of Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Li Ding
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Caitlyn M Hanna
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Martin J Gallagher
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Chengwen Zhou
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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9
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Al-Chami A, Ross A, Hayley S, Sun H. Early life stress facilitates synapse premature unsilencing to enhance AMPA receptor function in the developing hippocampus. J Neurophysiol 2020; 124:815-821. [PMID: 32783592 DOI: 10.1152/jn.00339.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic early life stress (ELS) increases vulnerability to psychopathologies and cognitive deficits in adulthood by disrupting the function of related neural circuits. However, whether this disruption emerges early in the developing brain remains largely unexplored. In the current study, using an established limited-bedding and nesting model of ELS in postnatal day (P)2-10 mice, we provide direct evidence that ELS caused early modification of hippocampal glutamatergic synapses in the developing brain. We demonstrated that ELS induced rapid enhancement of AMPA receptor function in hippocampal CA1 pyramidal neurons through a postsynaptic mechanism, and importantly, this was associated with premature unsilencing of NMDA receptor-only silent hippocampal synapses. These results suggest that potentiation of AMPAR function may represent an early mediator of ELS-induced alterations of neural networks in the developing brain and may potentially contribute to subsequent cognitive impairments later in life.NEW & NOTEWORTHY Early life stress (ELS) is known to increase the risk of later life cognitive deficits by disrupting neural circuit function. However, whether this disruption emerges early in the developing brain remains largely unexplored. The current study presents direct evidence that ELS prematurely unsilences hippocampal synapses to enhance AMPA receptor functions in a limited-bedding and nesting model, revealing an early mediator of ELS-induced neural circuit reorganizations.
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Affiliation(s)
- Aycheh Al-Chami
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Alysia Ross
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Shawn Hayley
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Hongyu Sun
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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10
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Sun H, Zhang H, Ross A, Wang TT, Al-Chami A, Wu SH. Developmentally Regulated Rebound Depolarization Enhances Spike Timing Precision in Auditory Midbrain Neurons. Front Cell Neurosci 2020; 14:236. [PMID: 32848625 PMCID: PMC7424072 DOI: 10.3389/fncel.2020.00236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 07/06/2020] [Indexed: 12/23/2022] Open
Abstract
The inferior colliculus (IC) is an auditory midbrain structure involved in processing biologically important temporal features of sounds. The responses of IC neurons to these temporal features reflect an interaction of synaptic inputs and neuronal biophysical properties. One striking biophysical property of IC neurons is the rebound depolarization produced following membrane hyperpolarization. To understand how the rebound depolarization is involved in spike timing, we made whole-cell patch clamp recordings from IC neurons in brain slices of P9-21 rats. We found that the percentage of rebound neurons was developmentally regulated. The precision of the timing of the first spike on the rebound increased when the neuron was repetitively injected with a depolarizing current following membrane hyperpolarization. The average jitter of the first spikes was only 0.5 ms. The selective T-type Ca2+ channel antagonist, mibefradil, significantly increased the jitter of the first spike of neurons in response to repetitive depolarization following membrane hyperpolarization. Furthermore, the rebound was potentiated by one to two preceding rebounds within a few hundred milliseconds. The first spike generated on the potentiated rebound was more precise than that on the non-potentiated rebound. With the addition of a calcium chelator, BAPTA, into the cell, the rebound potentiation no longer occurred, and the precision of the first spike on the rebound was not improved. These results suggest that the postinhibitory rebound mediated by T-type Ca2+ channel promotes spike timing precision in IC neurons. The rebound potentiation and precise spikes may be induced by increases in intracellular calcium levels.
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Affiliation(s)
- Hongyu Sun
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Hui Zhang
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Alysia Ross
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Ting Ting Wang
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Aycheh Al-Chami
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Shu Hui Wu
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
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11
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Sun H, Takesian AE, Wang TT, Lippman-Bell JJ, Hensch TK, Jensen FE. Early Seizures Prematurely Unsilence Auditory Synapses to Disrupt Thalamocortical Critical Period Plasticity. Cell Rep 2019; 23:2533-2540. [PMID: 29847785 PMCID: PMC6446922 DOI: 10.1016/j.celrep.2018.04.108] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 01/02/2018] [Accepted: 04/25/2018] [Indexed: 12/31/2022] Open
Abstract
Heightened neural excitability in infancy and childhood results in increased susceptibility to seizures. Such early-life seizures are associated with language deficits and autism that can result from aberrant development of the auditory cortex. Here, we show that early-life seizures disrupt a critical period (CP) for tonotopic map plasticity in primary auditory cortex (A1). We show that this CP is characterized by a prevalence of “silent,” NMDA-receptor (NMDAR)-only, glutamate receptor synapses in auditory cortex that become “unsilenced” due to activity-dependent AMPA receptor (AMPAR) insertion. Induction of seizures prior to this CP occludes tonotopic map plasticity by prematurely unsilencing NMDAR-only synapses. Further, brief treatment with the AMPAR antagonist NBQX following seizures, prior to the CP, prevents synapse unsilencing and permits subsequent A1 plasticity. These findings reveal that early-life seizures modify CP regulators and suggest that therapeutic targets for early post-seizure treatment can rescue CP plasticity.
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Affiliation(s)
- Hongyu Sun
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neuroscience, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Anne E Takesian
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115, USA
| | - Ting Ting Wang
- Department of Neuroscience, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Jocelyn J Lippman-Bell
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Takao K Hensch
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115, USA; Center for Brain Science, Department of Molecular & Cellular Biology, Harvard University, 52 Oxford St., Cambridge, MA 02138, USA.
| | - Frances E Jensen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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12
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Lee JS, Lee Y, André EA, Lee KJ, Nguyen T, Feng Y, Jia N, Harris BT, Burns MP, Pak DTS. Inhibition of Polo-like kinase 2 ameliorates pathogenesis in Alzheimer's disease model mice. PLoS One 2019; 14:e0219691. [PMID: 31306446 PMCID: PMC6629081 DOI: 10.1371/journal.pone.0219691] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/28/2019] [Indexed: 12/19/2022] Open
Abstract
Alzheimer disease (AD) is a neurodegenerative disorder characterized by pathological hallmarks of neurofibrillary tangles and amyloid plaques. The plaques are formed by aggregation and accumulation of amyloid β (Aβ), a cleavage fragment of amyloid precursor protein (APP). Enhanced neuronal activity and seizure events are frequently observed in AD, and elevated synaptic activity promotes Aβ production. However, the mechanisms that link synaptic hyperactivity to APP processing and AD pathogenesis are not well understood. We previously found that Polo-like kinase 2 (Plk2), a homeostatic repressor of neuronal overexcitation, promotes APP β-processing in vitro. Here, we report that Plk2 stimulates Aβ production in vivo, and that Plk2 levels are elevated in a spatiotemporally regulated manner in brains of AD mouse models and human AD patients. Genetic disruption of Plk2 kinase function reduces plaque deposits and activity-dependent Aβ production. Furthermore, pharmacological Plk2 inhibition hinders Aβ formation, synapse loss, and memory decline in an AD mouse model. Thus, Plk2 links synaptic overactivity to APP β-processing, Aβ production, and disease-relevant phenotypes in vivo, suggesting that Plk2 may be a potential target for AD therapeutics.
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Affiliation(s)
- Ji Soo Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Yeunkum Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Emily A. André
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Kea Joo Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Thien Nguyen
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Yang Feng
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Nuo Jia
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Brent T. Harris
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Mark P. Burns
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States of America
| | - Daniel T. S. Pak
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
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13
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Novati A, Hentrich T, Wassouf Z, Weber JJ, Yu-Taeger L, Déglon N, Nguyen HP, Schulze-Hentrich JM. Environment-dependent striatal gene expression in the BACHD rat model for Huntington disease. Sci Rep 2018; 8:5803. [PMID: 29643462 PMCID: PMC5895842 DOI: 10.1038/s41598-018-24243-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Abstract
Huntington disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the huntingtin (HTT) gene which results in progressive neurodegeneration in the striatum, cortex, and eventually most brain areas. Despite being a monogenic disorder, environmental factors influence HD characteristics. Both human and mouse studies suggest that mutant HTT (mHTT) leads to gene expression changes that harbor potential to be modulated by the environment. Yet, the underlying mechanisms integrating environmental cues into the gene regulatory program have remained largely unclear. To better understand gene-environment interactions in the context of mHTT, we employed RNA-seq to examine effects of maternal separation (MS) and environmental enrichment (EE) on striatal gene expression during development of BACHD rats. We integrated our results with striatal consensus modules defined on HTT-CAG length and age-dependent co-expression gene networks to relate the environmental factors with disease progression. While mHTT was the main determinant of expression changes, both MS and EE were capable of modulating these disturbances, resulting in distinctive and in several cases opposing effects of MS and EE on consensus modules. This bivalent response to maternal separation and environmental enrichment may aid in explaining their distinct effects observed on disease phenotypes in animal models of HD and related neurodegenerative disorders.
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Affiliation(s)
- Arianna Novati
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Thomas Hentrich
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Zinah Wassouf
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Jonasz J Weber
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Libo Yu-Taeger
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Nicole Déglon
- Department of Clinical Neurosciences (DNC), Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Huu Phuc Nguyen
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany. .,Department of Human Genetics, Ruhr-University Bochum, Bochum, Germany.
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14
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André EA, Forcelli PA, Pak DT. What goes up must come down: homeostatic synaptic plasticity strategies in neurological disease. FUTURE NEUROLOGY 2018; 13:13-21. [PMID: 29379396 DOI: 10.2217/fnl-2017-0028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/07/2017] [Indexed: 11/21/2022]
Abstract
Brain activity levels are tightly regulated to minimize imbalances in activity state. Deviations from the normal range of activity are deleterious and often associated with neurological disorders. To maintain optimal levels of activity, regulatory mechanisms termed homeostatic synaptic plasticity establish desired 'set points' for neural activity, monitor the network for deviations from the set point and initiate compensatory responses to return activity to the appropriate level that permits physiological function [1,2]. We speculate that impaired homeostatic control may contribute to the etiology of various neurological disorders including epilepsy and Alzheimer's disease, two disorders that exhibit hyperexcitability as a key feature during pathogenesis. Here, we will focus on recent progress in developing homeostatic regulation of neural activity as a therapeutic tool.
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Affiliation(s)
- Emily A André
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
| | - Patrick A Forcelli
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
| | - Daniel Ts Pak
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
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15
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Dunn R, Queenan BN, Pak DTS, Forcelli PA. Divergent effects of levetiracetam and tiagabine against spontaneous seizures in adult rats following neonatal hypoxia. Epilepsy Res 2017; 140:1-7. [PMID: 29227795 DOI: 10.1016/j.eplepsyres.2017.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 10/09/2017] [Accepted: 12/02/2017] [Indexed: 01/03/2023]
Abstract
Animal models are valuable tools for screening novel therapies for patients who suffer from epilepsy. However, a wide array of models are necessary to cover the diversity of human epilepsies. In humans, neonatal hypoxia (or hypoxia-ischemia) is one of the most common causes of epilepsy early in life. Hypoxia-induced seizures (HS) during the neonatal period can also lead to spontaneous seizures in adulthood. This phenomenon, i.e., early-life hypoxia leading to adult epilepsy - is also seen in experimental models, including rats. However, it is not known which anti-seizure medications are most effective at managing adult epilepsy resulting from neonatal HS. Here, we examined the efficacy of three anti-seizure medications against spontaneous seizures in adult rats with a history of neonatal HS: (1) phenobarbital (PHB), the oldest epilepsy medicine still in use today; (2) levetiracetam (LEV); and (3) tiagabine (TGB). Both LEV and TGB are relatively new anticonvulsant drugs that are ineffective in traditional seizure models, but strikingly effective in other models. We found that PHB and LEV decreased seizures in adult rats with a history of HS, whereas TGB exacerbated seizures. These divergent drug effects indicate that the HS model may be useful for differentiating the clinical efficacy of putative epilepsy therapies.
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Affiliation(s)
- Raymond Dunn
- Department of Pharmacology and Physiology, United States
| | - Bridget N Queenan
- Department of Pharmacology and Physiology, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States; Neuroscience Research Institute, Department of Mechanical Engineering; Department of Physics, University sof California, Santa Barbara, Santa Barbara, CA, United States
| | - Daniel T S Pak
- Department of Pharmacology and Physiology, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States.
| | - Patrick A Forcelli
- Department of Pharmacology and Physiology, United States; Department of Neuroscience, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States.
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16
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Huang C, Hu W, Wang J, Tong L, Lu X, Wu F, Ling Y, Jiang B, Zhang W, Chen Z, Xiong Q, Qin Y, Yang R. Methylene blue increases the amount of HSF1 through promotion of PKA-mediated increase in HSF1-p300 interaction. Int J Biochem Cell Biol 2017; 84:75-88. [DOI: 10.1016/j.biocel.2017.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 02/07/2023]
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17
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Lippman-Bell JJ, Zhou C, Sun H, Feske JS, Jensen FE. Early-life seizures alter synaptic calcium-permeable AMPA receptor function and plasticity. Mol Cell Neurosci 2016; 76:11-20. [PMID: 27521497 DOI: 10.1016/j.mcn.2016.08.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 07/15/2016] [Accepted: 08/09/2016] [Indexed: 12/31/2022] Open
Abstract
Calcium (Ca2+)-mediated4 signaling pathways are critical to synaptic plasticity. In adults, the NMDA glutamate receptor (NMDAR) represents a major route for activity-dependent synaptic Ca2+ entry. However, during neonatal development, when synaptic plasticity is particularly high, many AMPA glutamate receptors (AMPARs) are also permeable to Ca2+ (CP-AMPAR) due to low GluA2 subunit expression, providing an additional route for activity- and glutamate-dependent Ca2+ influx and subsequent signaling. Therefore, altered hippocampal Ca2+ signaling may represent an age-specific pathogenic mechanism. We thus aimed to assess Ca2+ responses 48h after hypoxia-induced neonatal seizures (HS) in postnatal day (P)10 rats, a post-seizure time point at which we previously reported LTP attenuation. We found that Ca2+ responses were higher in brain slices from post-HS rats than in controls and that this increase was CP-AMPAR-dependent. To determine whether synaptic CP-AMPAR expression was also altered post-HS, we assessed the expression of GluA2 at hippocampal synapses and the expression of long-term depression (LTD), which has been linked to the presence of synaptic GluA2. Here we report a decrease 48h after HS in synaptic GluA2 expression at synapses and LTD in hippocampal CA1. Given the potentially critical role of AMPAR trafficking in disease progression, we aimed to establish whether post-seizure in vivo AMPAR antagonist treatment prevented the enhanced Ca2+ responses, changes in GluA2 synaptic expression, and diminished LTD. We found that NBQX treatment prevents all three of these post-seizure consequences, further supporting a critical role for AMPARs as an age-specific therapeutic target.
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Affiliation(s)
- Jocelyn J Lippman-Bell
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Boston Children's Hospital, Boston, MA 02114, United States; Philadelphia College of Osteopathic Medicine, Philadelphia, PA 19131, United States
| | - Chengwen Zhou
- Boston Children's Hospital, Boston, MA 02114, United States
| | - Hongyu Sun
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Boston Children's Hospital, Boston, MA 02114, United States
| | - Joel S Feske
- Boston Children's Hospital, Boston, MA 02114, United States
| | - Frances E Jensen
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Boston Children's Hospital, Boston, MA 02114, United States.
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18
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Sheng Y, Zhang L, Su SC, Tsai LH, Julius Zhu J. Cdk5 is a New Rapid Synaptic Homeostasis Regulator Capable of Initiating the Early Alzheimer-Like Pathology. Cereb Cortex 2016; 26:2937-51. [PMID: 26088971 PMCID: PMC4898661 DOI: 10.1093/cercor/bhv032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase implicated in synaptic plasticity, behavior, and cognition, yet its synaptic function remains poorly understood. Here, we report that physiological Cdk5 signaling in rat hippocampal CA1 neurons regulates homeostatic synaptic transmission using an unexpectedly rapid mechanism that is different from all known slow homeostatic regulators, such as beta amyloid (Aβ) and activity-regulated cytoskeleton-associated protein (Arc, aka Arg3.1). Interestingly, overproduction of the potent Cdk5 activator p25 reduces synapse density, and dynamically regulates synaptic size by suppressing or enhancing Aβ/Arc production. Moreover, chronic overproduction of p25, seen in Alzheimer's patients, induces initially concurrent reduction in synapse density and increase in synaptic size characteristic of the early Alzheimer-like pathology, and later persistent synapse elimination in intact brains. These results identify Cdk5 as the regulator of a novel rapid form of homeostasis at central synapses and p25 as the first molecule capable of initiating the early Alzheimer's synaptic pathology.
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Affiliation(s)
- Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing100871, China
- Current address: Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Lei Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Susan C. Su
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J. Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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19
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Park WJ, Kim SY, Kim YR, Park JW. Bortezomib alleviates drug-induced liver injury by regulating CYP2E1 gene transcription. Int J Mol Med 2016; 37:613-22. [PMID: 26797017 PMCID: PMC4771096 DOI: 10.3892/ijmm.2016.2461] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 01/14/2016] [Indexed: 12/27/2022] Open
Abstract
Acute liver failure, i.e., the fatal deterioration of liver function, is the most common indication that emergency liver transplantation is necessary. Moreover, in the USA, drug-induced liver injury (DILI), including acetaminophen (APAP)-induced hepatotoxicity, is the main cause of acute liver failure. Matching a donor for liver transplantation is extremely difficult, and thus the development of a novel therapy for DILI is urgently needed. Following recent approval by the FDA of the proteasomal inhibitor bortezomib, its therapeutic effects on various human diseases, including solid and hematologic malignancies, have been validated. However, the specific action of proteasomal inhibition in cases of DILI had not been elucidated prior to this study. To examine the effects of proteasomal inhibition in DILI experimentally, male C56Bl/6 mice were injected with 1 mg bortezomib/kg before APAP treatment. Bortezomib not only alleviated APAP-induced hepatotoxicity in a time- and dose-dependent manner, it also alleviated CCl4- and thioacetamide-induced hepatotoxicity. We also noted that bortezomib significantly reduced cytochrome P450 2E1 (CYP2E1) expression and activity in the liver, which was accompanied by the induction of endoplasmic reticulum (ER) stress. In addition, bortezomib decreased hepatocyte nuclear factor‑1α-induced promoter activation of CYP2E1 in Hep3B cells. By contrast, another proteasome inhibitor, MG132, did not cause ER stress and did not markedly affect CYP2E1 enzyme activity. Liver injury induced by APAP was aggravated by MG132, possibly via elevation of connexin 32 expression. This study suggests that proteasome inhibition has different effects in cases of DILI depending on the specific inhibitor being used. Furthermore, results from the mouse model indicated that bortezomib, but not MG132, was effective in alleviating DILI. ER stress induced by proteasome inhibition has previously been shown to exert various effects on DILI patients, and thus each available proteasomal inhibitor should be evaluated individually in order to determine its potential for clinical application.
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Affiliation(s)
- Woo-Jae Park
- Department of Biochemistry, School of Medicine, Gachon University, Incheon 406-799, Republic of Korea
| | - So-Yeon Kim
- Department of Biochemistry, School of Medicine, Ewha Womans University, Yang Cheon-Gu, Seoul 158-710, Republic of Korea
| | - Ye-Ryung Kim
- Department of Biochemistry, School of Medicine, Ewha Womans University, Yang Cheon-Gu, Seoul 158-710, Republic of Korea
| | - Joo-Won Park
- Department of Biochemistry, School of Medicine, Ewha Womans University, Yang Cheon-Gu, Seoul 158-710, Republic of Korea
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20
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Siebel AM, Menezes FP, da Costa Schaefer I, Petersen BD, Bonan CD. Rapamycin suppresses PTZ-induced seizures at different developmental stages of zebrafish. Pharmacol Biochem Behav 2015; 139 Pt B:163-8. [DOI: 10.1016/j.pbb.2015.05.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/13/2015] [Accepted: 05/28/2015] [Indexed: 11/25/2022]
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21
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Sun H, Juul HM, Jensen FE. Models of hypoxia and ischemia-induced seizures. J Neurosci Methods 2015; 260:252-60. [PMID: 26434705 DOI: 10.1016/j.jneumeth.2015.09.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/22/2015] [Indexed: 01/19/2023]
Abstract
Despite greater understanding and improved management, seizures continue to be a major problem in childhood. Neonatal seizures are often refractory to conventional antiepileptic drugs, and can result in later life epilepsy and cognitive deficits, conditions for which there are no specific treatments. Hypoxic and/or ischemic encephalopathy (HIE) is the most common cause for neonatal seizures, and accounts for more than two-thirds of neonatal seizure cases. A better understanding of the cellular and molecular mechanisms is essential for identifying new therapeutic strategies that control the neonatal seizures and its cognitive consequences. This heavily relies on animal models that play a critical role in discovering novel mechanisms underlying both epileptogenesis and associated cognitive impairments. To date, a number of animal models have provided a tremendous amount of information regarding the pathophysiology of HIE-induced neonatal seizures. This review provides an overview on the most important features of the main animal models of HIE-induced seizures. In particular, we focus on the methodology of seizure induction and the characterizations of post-HIE injury consequences. These aspects of HIE-induced seizure models are discussed in the light of the suitability of these models in studying human HIE-induced seizures.
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Affiliation(s)
- Hongyu Sun
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Halvor M Juul
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Frances E Jensen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
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22
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Zhou C, Sun H, Klein PM, Jensen FE. Neonatal seizures alter NMDA glutamate receptor GluN2A and 3A subunit expression and function in hippocampal CA1 neurons. Front Cell Neurosci 2015; 9:362. [PMID: 26441533 PMCID: PMC4585040 DOI: 10.3389/fncel.2015.00362] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/31/2015] [Indexed: 12/02/2022] Open
Abstract
Neonatal seizures are commonly caused by hypoxic and/or ischemic injury during birth and can lead to long-term epilepsy and cognitive deficits. In a rodent hypoxic seizure (HS) model, we have previously demonstrated a critical role for seizure-induced enhancement of the AMPA subtype of glutamate receptor (GluA) in epileptogenesis and cognitive consequences, in part due to GluA maturational upregulation of expression. Similarly, as the expression and function of the N-Methyl-D-aspartate (NMDA) subtype of glutamate receptor (GluN) is also developmentally controlled, we examined how early life seizures during the critical period of synaptogenesis could modify GluN development and function. In a postnatal day (P)10 rat model of neonatal seizures, we found that seizures could alter GluN2/3 subunit composition of GluNs and physiological function of synaptic GluNs. In hippocampal slices removed from rats within 48–96 h following seizures, the amplitudes of synaptic GluN-mediated evoked excitatory postsynaptic currents (eEPSCs) were elevated in CA1 pyramidal neurons. Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg2+ sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively. These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein. These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain.
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Affiliation(s)
- Chengwen Zhou
- Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA ; Program in Neurobiology, Harvard Medical School Boston, MA, USA
| | - Hongyu Sun
- Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA ; Program in Neurobiology, Harvard Medical School Boston, MA, USA ; Department of Neurology, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, USA
| | - Peter M Klein
- Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA
| | - Frances E Jensen
- Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA ; Program in Neurobiology, Harvard Medical School Boston, MA, USA ; Department of Neurology, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, USA
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23
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Rodriguez-Alvarez N, Jimenez-Mateos EM, Dunleavy M, Waddington JL, Boylan GB, Henshall DC. Effects of hypoxia-induced neonatal seizures on acute hippocampal injury and later-life seizure susceptibility and anxiety-related behavior in mice. Neurobiol Dis 2015; 83:100-14. [PMID: 26341542 DOI: 10.1016/j.nbd.2015.08.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/06/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022] Open
Abstract
Seizures are common during the neonatal period, often due to hypoxic-ischemic encephalopathy and may contribute to acute brain injury and the subsequent development of cognitive deficits and childhood epilepsy. Here we explored short- and long-term consequences of neonatal hypoxia-induced seizures in 7 day old C57BL/6J mice. Seizure activity, molecular markers of hypoxia and histological injury were investigated acutely after hypoxia and response to chemoconvulsants and animal behaviour was explored at adulthood. Hypoxia was induced by exposing pups to 5% oxygen for 15 min (global hypoxia). Electrographically defined seizures with behavioral correlates occurred in 95% of these animals and seizures persisted for many minutes after restitution of normoxia. There was minimal morbidity or mortality. Pre- or post-hypoxia injection of phenobarbital (50mg/kg) had limited efficacy at suppressing seizures. The hippocampus from neonatal hypoxia-seizure mice displayed increased expression of vascular endothelial growth factor and the immediate early gene c-fos, minimal histological evidence of cell injury and activation of caspase-3 in scattered neurons. Behavioral analysis of mice five weeks after hypoxia-induced seizures detected novel anxiety-related and other behaviors, while performance in a spatial memory test was similar to controls. Seizure threshold tests with kainic acid at six weeks revealed that mice previously subject to neonatal hypoxia-induced seizures developed earlier, more frequent and longer-duration seizures. This study defines a set of electro-clinical, molecular, pharmacological and behavioral consequences of hypoxia-induced seizures that indicate short- and long-term deleterious outcomes and may be a useful model to investigate the pathophysiology and treatment of neonatal seizures in humans.
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Affiliation(s)
| | - Eva M Jimenez-Mateos
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Mark Dunleavy
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - John L Waddington
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Geraldine B Boylan
- Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland
| | - David C Henshall
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland; Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.
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24
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Sosanya NM, Brager DH, Wolfe S, Niere F, Raab-Graham KF. Rapamycin reveals an mTOR-independent repression of Kv1.1 expression during epileptogenesis. Neurobiol Dis 2014; 73:96-105. [PMID: 25270294 DOI: 10.1016/j.nbd.2014.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 08/11/2014] [Accepted: 09/21/2014] [Indexed: 01/12/2023] Open
Abstract
Changes in ion channel expression are implicated in the etiology of epilepsy. However, the molecular leading to long-term aberrant expression of ion channels are not well understood. The mechanistic/mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that mediates activity-dependent protein synthesis in neurons. mTOR is overactive in epilepsy, suggesting that excessive protein synthesis may contribute to the neuronal pathology. In contrast, we found that mTOR activity and the microRNA miR-129-5p reduce the expression of the voltage-gated potassium channel Kv1.1 in an animal model of temporal lobe epilepsy (TLE). When mTOR activity is low, Kv1.1 expression is high and the frequency of behavioral seizures is low. However, as behavioral seizure activity rises, mTOR activity increases and Kv1.1 protein levels drop. In CA1 pyramidal neurons, the reduction in Kv1.1 lowers the threshold for action potential firing. Interestingly, blocking mTOR activity with rapamycin reduces behavioral seizures and temporarily keeps Kv1.1 levels elevated. Overtime, seizure activity increases and Kv1.1 protein decreases in all animals, even those treated with rapamycin. Notably, the concentration of miR-129-5p, the negative regulator of Kv1.1 mRNA translation, increases by 21days post-status epilepticus (SE), sustaining Kv1.1 mRNA translational repression. Our results suggest that following kainic-acid induced status epilepticus there are two phases of Kv1.1 repression: (1) an initial mTOR-dependent repression of Kv1.1 that is followed by (2) a miR-129-5p persistent reduction of Kv1.1.
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Affiliation(s)
- Natasha M Sosanya
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, USA; Institute for Cell and Molecular Biology, University of Texas at Austin, USA
| | - Darrin H Brager
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, USA
| | - Sarah Wolfe
- Institute for Cell and Molecular Biology, University of Texas at Austin, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin University Station C7000, Austin, TX 78712, USA
| | - Farr Niere
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, USA
| | - Kimberly F Raab-Graham
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, USA; Institute for Cell and Molecular Biology, University of Texas at Austin, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin University Station C7000, Austin, TX 78712, USA.
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Lasarge CL, Danzer SC. Mechanisms regulating neuronal excitability and seizure development following mTOR pathway hyperactivation. Front Mol Neurosci 2014; 7:18. [PMID: 24672426 PMCID: PMC3953715 DOI: 10.3389/fnmol.2014.00018] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 02/27/2014] [Indexed: 01/19/2023] Open
Abstract
The phosphatidylinositol-3-kinase/phosphatase and tensin homolog (PTEN)-mammalian target of rapamycin (mTOR) pathway regulates a variety of neuronal functions, including cell proliferation, survival, growth, and plasticity. Dysregulation of the pathway is implicated in the development of both genetic and acquired epilepsies. Indeed, several causal mutations have been identified in patients with epilepsy, the most prominent of these being mutations in PTEN and tuberous sclerosis complexes 1 and 2 (TSC1, TSC2). These genes act as negative regulators of mTOR signaling, and mutations lead to hyperactivation of the pathway. Animal models deleting PTEN, TSC1, and TSC2 consistently produce epilepsy phenotypes, demonstrating that increased mTOR signaling can provoke neuronal hyperexcitability. Given the broad range of changes induced by altered mTOR signaling, however, the mechanisms underlying seizure development in these animals remain uncertain. In transgenic mice, cell populations with hyperactive mTOR have many structural abnormalities that support recurrent circuit formation, including somatic and dendritic hypertrophy, aberrant basal dendrites, and enlargement of axon tracts. At the functional level, mTOR hyperactivation is commonly, but not always, associated with enhanced synaptic transmission and plasticity. Moreover, these populations of abnormal neurons can affect the larger network, inducing secondary changes that may explain paradoxical findings reported between cell and network functioning in different models or at different developmental time points. Here, we review the animal literature examining the link between mTOR hyperactivation and epileptogenesis, emphasizing the impact of enhanced mTOR signaling on neuronal form and function.
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Affiliation(s)
- Candi L Lasarge
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA ; Department of Anesthesia, University of Cincinnati Cincinnati, OH, USA ; Department of Pediatrics, University of Cincinnati Cincinnati, OH, USA
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Lippman-Bell JJ, Rakhade SN, Klein PM, Obeid M, Jackson MC, Joseph A, Jensen FE. AMPA receptor antagonist NBQX attenuates later-life epileptic seizures and autistic-like social deficits following neonatal seizures. Epilepsia 2013; 54:1922-32. [PMID: 24117347 DOI: 10.1111/epi.12378] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2013] [Indexed: 12/12/2022]
Abstract
PURPOSE To determine whether AMPA receptor (AMPAR) antagonist NBQX can prevent early mammalian target of rapamycin (mTOR) pathway activation and long-term sequelae following neonatal seizures in rats, including later-life spontaneous recurrent seizures, CA3 mossy fiber sprouting, and autistic-like social deficits. METHODS Long-Evans rats experienced hypoxia-induced neonatal seizures (HS) at postnatal day (P)10. NBQX (20 mg/kg) was administered immediately following HS (every 12 h × 4 doses). Twelve hours post-HS, we assessed mTOR activation marker phosphorylated p70-S6 kinase (p-p70S6K) in hippocampus and cortex of vehicle (HS + V) or NBQX-treated post-HS rats (HS + N) versus littermate controls (C + V). Spontaneous seizure activity was compared between groups by epidural cortical electroencephalography (EEG) at P70-100. Aberrant mossy fiber sprouting was measured using Timm staining. Finally, we assessed behavior between P30 and P38. KEY FINDINGS Postseizure NBQX treatment significantly attenuated seizure-induced increases in p-p70S6K in the hippocampus (p < 0.01) and cortex (p < 0.001). Although spontaneous recurrent seizures increased in adulthood in HS + V rats compared to controls (3.22 ± 1 seizures/h; p = 0.03), NBQX significantly attenuated later-life seizures (0.14 ± 0.1 seizures/h; p = 0.046). HS + N rats showed less aberrant mossy fiber sprouting (115 ± 8.0%) than vehicle-treated post-HS rats (174 ± 10%, p = 0.004), compared to controls (normalized to 100%). Finally, NBQX treatment prevented alterations in later-life social behavior; post-HS rats showed significantly decreased preference for a novel over a familiar rat (71.0 ± 12 s) compared to controls (99.0 ± 15.6 s; p < 0.01), whereas HS + N rats showed social novelty preference similar to controls (114.3 ± 14.1 s). SIGNIFICANCE Brief NBQX administration during the 48 h postseizure in P10 Long-Evans rats suppresses transient mTOR pathway activation and attenuates spontaneous recurrent seizures, social preference deficits, and mossy fiber sprouting observed in vehicle-treated adult rats after early life seizures. These results suggest that acute AMPAR antagonist treatment during the latent period immediately following neonatal HS can modify seizure-induced activation of mTOR, reduce the frequency of later-life seizures, and protect against CA3 mossy fiber sprouting and autistic-like social deficits.
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Affiliation(s)
- Jocelyn J Lippman-Bell
- Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts, U.S.A; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
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Queenan BN, Pak DTS. Homeostatic synaptic plasticity in the hippocampus: therapeutic prospects for seizure control? FUTURE NEUROLOGY 2013. [DOI: 10.2217/fnl.13.24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Bridget N Queenan
- Interdisciplinary Program in Neuroscience, Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
| | - Daniel TS Pak
- Interdisciplinary Program in Neuroscience, Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA.
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