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Li RR, Yan J, Chen H, Zhang WW, Hu YB, Zhang J, Hu ZA, Xiong Y, Yao ZX, Hu B. Sleep Deprivation Impairs Learning-Induced Increase in Hippocampal Sharp Wave Ripples and Associated Spike Dynamics during Recovery Sleep. Cereb Cortex 2021; 32:824-838. [PMID: 34383018 DOI: 10.1093/cercor/bhab247] [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] [Received: 04/15/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 11/14/2022] Open
Abstract
Sleep deprivation (SD) causes deficits in off-line memory consolidation, but the underlying network oscillation mechanisms remain unclear. Hippocampal sharp wave ripple (SWR) oscillations play a critical role in off-line memory consolidation. Therefore, we trained mice to learn a hippocampus-dependent trace eyeblink conditioning (tEBC) task and explored the influence of 1.5-h postlearning SD on hippocampal SWRs and related spike dynamics during recovery sleep. We found an increase in hippocampal SWRs during postlearning sleep, which predicted the consolidation of tEBC in conditioned mice. In contrast, sleep-deprived mice showed a loss of tEBC learning-induced increase in hippocampal SWRs during recovery sleep. Moreover, the sleep-deprived mice exhibited weaker reactivation of tEBC learning-associated pyramidal cells in hippocampal SWRs during recovery sleep. In line with these findings, tEBC consolidation was impaired in sleep-deprived mice. Furthermore, sleep-deprived mice showed augmented fast excitation from pyramidal cells to interneurons and enhanced participation of interneurons in hippocampal SWRs during recovery sleep. Among various interneurons, parvalbumin-expressing interneurons specifically exhibited overexcitation during hippocampal SWRs. Our findings suggest that altered hippocampal SWRs and associated spike dynamics during recovery sleep may be candidate network oscillation mechanisms underlying SD-induced memory deficits.
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Affiliation(s)
- Rong-Rong Li
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Jie Yan
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Hao Chen
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Wei-Wei Zhang
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Yu-Bo Hu
- Department of Orthopaedics, Daping Hospital, Army Medical University, Chongqing 400042, China
| | - Jie Zhang
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Zhi-An Hu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Yan Xiong
- Department of Orthopaedics, Daping Hospital, Army Medical University, Chongqing 400042, China
| | - Zhong-Xiang Yao
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Bo Hu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China.,Brain and Intelligence Research Key Laboratory of Chongqing Education Commission, Army Medical University, Chongqing 400038, China
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2
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Liu H, Zhang S, Zhang L. Epileptiform activity in mouse hippocampal slices induced by moderate changes in extracellular Mg 2+, Ca 2+, and K . BMC Neurosci 2021; 22:46. [PMID: 34301200 PMCID: PMC8305515 DOI: 10.1186/s12868-021-00650-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rodent brain slices-particularly hippocampal slices-are widely used in experimental investigations of epileptiform activity. Oxygenated artificial cerebrospinal fluid (ACSF) is used to maintain slices in vitro. Physiological or standard ACSF containing 3-3.5 mM K+, 1-2 mM Mg2+, and 1-3 mM Ca2+ generally does not induce population epileptiform activity, which can be induced by ACSF with high K+ (8-10 mM), low Mg2+, or low Ca2+ alone or in combination. While low-Mg2+ ACSF without intentionally added Mg salt but with contaminating Mg2+ (≤ 50-80 µM) from other salts can induce robust epileptiform activity in slices, it is unclear whether such epileptiform activity can be achieved using ACSF with moderately decreased Mg2+. To explore this issue, we examined the effects of moderately modified (m)ACSF with 0.8 mM Mg2+, 1.3 mM Ca2+, and 5.7 mM K+ on induction of epileptiform discharges in mouse hippocampal slices. RESULTS Hippocampal slices were prepared from young (21-28 days old), middle-aged (13-14 months old), and aged (24-26 months old) C57/BL6 mice. Conventional thin (0.4 mm) and thick (0.6 mm) slices were obtained using a vibratome and pretreated with mACSF at 35-36 °C for 1 h prior to recordings. During perfusion with mACSF at 35-36 °C, spontaneous or self-sustained epileptiform field potentials following high-frequency stimulation were frequently recorded in slices pretreated with mACSF but not in those without the pretreatment. Seizure-like ictal discharges were more common in thick slices than in thin slices. CONCLUSIONS Prolonged exposure to mACSF by pretreatment and subsequent perfusion can induce epileptiform field potentials in mouse hippocampal slices.
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Affiliation(s)
- Haiyu Liu
- Department of Neurosurgery, The First Hospital of Jilin University, Jilin, China.,Graduate School of Tianjin Medical University, Tianjin, China.,Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Sai Zhang
- Graduate School of Tianjin Medical University, Tianjin, China.
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Toronto, ON, Canada. .,Department of Medicine (Neurology), University of Toronto, Toronto, ON, Canada.
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3
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Lehr AB, Kumar A, Tetzlaff C, Hafting T, Fyhn M, Stöber TM. CA2 beyond social memory: Evidence for a fundamental role in hippocampal information processing. Neurosci Biobehav Rev 2021; 126:398-412. [PMID: 33775693 DOI: 10.1016/j.neubiorev.2021.03.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/16/2021] [Accepted: 03/18/2021] [Indexed: 01/16/2023]
Abstract
Hippocampal region CA2 has received increased attention due to its importance in social recognition memory. While its specific function remains to be identified, there are indications that CA2 plays a major role in a variety of situations, widely extending beyond social memory. In this targeted review, we highlight lines of research which have begun to converge on a more fundamental role for CA2 in hippocampus-dependent memory processing. We discuss recent proposals that speak to the computations CA2 may perform within the hippocampal circuit.
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Affiliation(s)
- Andrew B Lehr
- Department of Computational Neuroscience, University of Göttingen, Germany; Bernstein Center for Computational Neuroscience, University of Göttingen, Germany; Department of Computational Physiology, Simula Research Laboratory, Lysaker, Norway; Centre for Integrative Neuroplasticity, University of Oslo, Norway.
| | - Arvind Kumar
- Department of Computational Science and Technology, KTH Royal Institute of Technology, Sweden
| | - Christian Tetzlaff
- Department of Computational Neuroscience, University of Göttingen, Germany; Bernstein Center for Computational Neuroscience, University of Göttingen, Germany
| | - Torkel Hafting
- Centre for Integrative Neuroplasticity, University of Oslo, Norway; Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Marianne Fyhn
- Centre for Integrative Neuroplasticity, University of Oslo, Norway; Department of Biosciences, University of Oslo, Norway
| | - Tristan M Stöber
- Department of Computational Physiology, Simula Research Laboratory, Lysaker, Norway; Centre for Integrative Neuroplasticity, University of Oslo, Norway; Department of Informatics, University of Oslo, Norway.
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4
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Zavala-Tecuapetla C, Orozco-Suarez S, Manjarrez J, Cuellar-Herrera M, Vega-Garcia A, Buzoianu-Anguiano V. Activation of adenosine receptors modulates the efflux transporters in brain capillaries and restores the anticonvulsant effect of carbamazepine in carbamazepine resistant rats developed by window-pentylenetetrazole kindling. Brain Res 2019; 1726:146516. [PMID: 31634453 DOI: 10.1016/j.brainres.2019.146516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 10/15/2019] [Accepted: 10/17/2019] [Indexed: 01/14/2023]
Abstract
Up-regulation of efflux transporters in brain capillaries may lead to the decreased therapeutic efficacy of antiepileptic drugs in patients with Drug Resistant Epilepsy. Adenosine receptor activation in brain capillaries can modulate blood-brain barrier permeability by decreasing the protein levels and function of efflux transporters. Therefore, we aimed to investigate whether the activation of adenosine receptors improves convulsions outcome in carbamazepine (CBZ) resistant animals and modulates the protein levels of efflux transporters (P-GP, MRP1, MRP2) in brain capillaries. We employed the window-pentylenetetrazol (PTZ) kindling model to develop CBZ resistant rats by CBZ administration during the post-kindling phase, and tested if these animals displayed subsequent resistance to other antiepileptic drugs. Crucially, we investigated if the administration of a broad-spectrum adenosine agonist (NECA) improves convulsions control in CBZ resistant rats. Of potential therapeutic relevance, in CBZ resistant rats NECA restored the anticonvulsant effect of CBZ. We also evaluated how the resistance to CBZ and the activation of adenosine receptors with NECA affect protein levels of efflux transporters in brain capillaries, as quantified by western blot. While CBZ resistance was associated with the up-regulation of both P-GP/MRP2 in brain capillaries, with the administration of NECA in CBZ resistant rats, we observed a decrease of P-GP and an increase of MRP2 levels, in brain capillaries. Since the activation of adenosine receptors improves the outcome of convulsions probably through the modulation of the efflux transporters protein levels in brain capillaries, adenosine agonists could be useful as an adjunct therapy for the control of Drug Resistant Epilepsy.
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Affiliation(s)
- C Zavala-Tecuapetla
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, Insurgentes Sur 3877, La Fama, 14269 Mexico City, Mexico.
| | - S Orozco-Suarez
- Medical Research Unit in Neurological Diseases, Specialty Hospital, National Medical Center XXI Century, IMSS, Cuauhtemoc 330, Doctores, 06720 Mexico City, Mexico
| | - J Manjarrez
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, Insurgentes Sur 3877, La Fama, 14269 Mexico City, Mexico
| | - M Cuellar-Herrera
- Epilepsy Clinic, Hospital General de México, Dr. Eduardo Liceaga, Dr. Balmis 148, Doctores, 06720 Mexico City, Mexico
| | - A Vega-Garcia
- Medical Research Unit in Neurological Diseases, Specialty Hospital, National Medical Center XXI Century, IMSS, Cuauhtemoc 330, Doctores, 06720 Mexico City, Mexico; Department of Physiology, Faculty of Medicine, National Autonomous University of Mexico, Av. Universidad 3000, C.U., 04510 Mexico City, Mexico
| | - V Buzoianu-Anguiano
- Medical Research Unit in Neurological Diseases, Specialty Hospital, National Medical Center XXI Century, IMSS, Cuauhtemoc 330, Doctores, 06720 Mexico City, Mexico
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5
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Abstract
Caffeine promotes memory consolidation. Memory consolidation is thought to depend at least in part on hippocampal sharp waves (SWs). In the present study, we investigated the effect of bath-application of caffeine in spontaneously occurring SWs in mouse acute hippocampal slices. Caffeine induced an about 100% increase in the event frequency of SWs at concentrations of 60 and 200 µM. The effect of caffeine was reversible after washout of caffeine and was mimicked by an adenosine A1 receptor antagonist, but not by an A2A receptor antagonist. Caffeine increased SWs even in dentate-CA3 mini-slices without the CA2 regions, in which adenosine A1 receptors are abundantly expressed in the hippocampus. Thus, caffeine facilitates SWs by inhibiting adenosine A1 receptors in the hippocampal CA3 region or the dentate gyrus.
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Affiliation(s)
- Yusuke Watanabe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo.,Center for Information and Neural Networks, National Institute of Information and Communications Technology
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6
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Prominent differences in sharp waves, ripples and complex spike bursts between the dorsal and the ventral rat hippocampus. Neuroscience 2017; 352:131-143. [DOI: 10.1016/j.neuroscience.2017.03.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 12/17/2022]
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7
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Klaft ZJ, Hollnagel JO, Salar S, Calişkan G, Schulz SB, Schneider UC, Horn P, Koch A, Holtkamp M, Gabriel S, Gerevich Z, Heinemann U. Adenosine A1 receptor-mediated suppression of carbamazepine-resistant seizure-like events in human neocortical slices. Epilepsia 2016; 57:746-56. [PMID: 27087530 DOI: 10.1111/epi.13360] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The need for alternative pharmacologic strategies in treatment of epilepsies is pressing for about 30% of patients with epilepsy who do not experience satisfactory seizure control with present treatments. In temporal lobe epilepsy (TLE) even up to 80% of patients are pharmacoresistant, and surgical resection of the ictogenic tissue is only possible for a minority of TLE patients. In this study we investigate purinergic modulation of drug-resistant seizure-like events (SLEs) in human temporal cortex slices. METHODS Layer V/VI field potentials from a total of 77 neocortical slices from 17 pharmacoresistant patients were recorded to monitor SLEs induced by application of 8 mM [K(+) ] and 50 μm bicuculline. RESULTS Activating A1 receptors with a specific agonist completely suppressed SLEs in 73% of human temporal cortex slices. In the remaining slices, incidence of SLEs was markedly reduced. Because a subportion of slices can be pharmacosensitive, we tested effects of an A1 agonist, in slices insensitive to a high dose of carbamazepine (50 μm). Also in these cases the A1 agonist was equally efficient. Moreover, ATP and adenosine blocked or modulated SLEs, an effect mediated not by P2 receptors but rather by adenosine A1 receptors. SIGNIFICANCE Selective activation of A1 receptors mediates a strong anticonvulsant action in human neocortical slices from pharmacoresistant patients. We propose that our human slice model of seizure-like activity is a feasible option for future studies investigating new antiepileptic drug (AED) candidates.
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Affiliation(s)
- Zin-Juan Klaft
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jan-Oliver Hollnagel
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Seda Salar
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Gürsel Calişkan
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Steffen B Schulz
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ulf C Schneider
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Peter Horn
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Arend Koch
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Martin Holtkamp
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Epilepsy-Center Berlin-Brandenburg, Krankenhaus Königin Elisabeth Herzberge, Berlin, Germany
| | - Siegrun Gabriel
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Zoltan Gerevich
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Uwe Heinemann
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
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8
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Florez CM, Lukankin V, Sugumar S, McGinn R, Zhang ZJ, Zhang L, Carlen PL. Hypoglycemia-induced alterations in hippocampal intrinsic rhythms: Decreased inhibition, increased excitation, seizures and spreading depression. Neurobiol Dis 2015; 82:213-225. [PMID: 26093168 DOI: 10.1016/j.nbd.2015.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Seizures are the most common clinical presentation of severe hypoglycemia, usually as a side effect of insulin treatment for juvenile onset type 1 diabetes mellitus and advanced type 2 diabetes. We used the mouse thick hippocampal slice preparation to study the pathophysiology of hypoglycemia-induced seizures and the effects of severe glucose depletion on the isolated hippocampal rhythms from the CA3 circuitry. METHODS AND RESULTS Dropping the glucose perfusate concentration from the standard 10 mM to 1 mM produced epileptiform activity in 14/16 of the slices. Seizure-like events (SLEs) originated in the CA3 region and then spread into the CA1 region. Following the SLE, a spreading-depression (SD)-like event occurred (12/16 slices) with irreversible synaptic failure in the CA1 region (8/12 slices). CA3 SD-like events followed ~30 s after the SD-like event in the CA1 region. Less commonly, SD-like events originated in the CA3 region (4/12). Additionally, prior to the onset of the SLE in the CA3 area, there was decreased GABA correlated baseline SPW activity (bSPW), while there was increased large-amplitude sharp wave (LASW) activity, thought to originate from synchronous pyramidal cell firing. CA3 pyramidal cells displayed progressive tonic depolarization prior to the seizure which was resistant to synaptic transmission blockade. The initiation of hypoglycemic seizures and SD was prevented by AMPA/kainate or NMDA receptor blockade. CONCLUSIONS Severe glucose depletion induces rapid changes initiated in the intrinsic CA3 rhythms of the hippocampus including depressed inhibition and enhanced excitation, which may underlie the mechanisms of seizure generation and delayed spreading depression.
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Affiliation(s)
- C M Florez
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada; Division of Fundamental Neurobiology, TWRI, UHN, Toronto, Canada
| | - V Lukankin
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - S Sugumar
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - R McGinn
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - Z J Zhang
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - L Zhang
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - P L Carlen
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada; Division of Fundamental Neurobiology, TWRI, UHN, Toronto, Canada.
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9
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Extracellular calcium controls the expression of two different forms of ripple-like hippocampal oscillations. J Neurosci 2014; 34:2989-3004. [PMID: 24553939 DOI: 10.1523/jneurosci.2826-13.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hippocampal high-frequency oscillations (HFOs) are prominent in physiological and pathological conditions. During physiological ripples (100-200 Hz), few pyramidal cells fire together coordinated by rhythmic inhibitory potentials. In the epileptic hippocampus, fast ripples (>200 Hz) reflect population spikes (PSs) from clusters of bursting cells, but HFOs in the ripple and the fast ripple range are vastly intermixed. What is the meaning of this frequency range? What determines the expression of different HFOs? Here, we used different concentrations of Ca(2+) in a physiological range (1-3 mM) to record local field potentials and single cells in hippocampal slices from normal rats. Surprisingly, we found that this sole manipulation results in the emergence of two forms of HFOs reminiscent of ripples and fast ripples recorded in vivo from normal and epileptic rats, respectively. We scrutinized the cellular correlates and mechanisms underlying the emergence of these two forms of HFOs by combining multisite, single-cell and paired-cell recordings in slices prepared from a rat reporter line that facilitates identification of GABAergic cells. We found a major effect of extracellular Ca(2+) in modulating intrinsic excitability and disynaptic inhibition, two critical factors shaping network dynamics. Moreover, locally modulating the extracellular Ca(2+) concentration in an in vivo environment had a similar effect on disynaptic inhibition, pyramidal cell excitability, and ripple dynamics. Therefore, the HFO frequency band reflects a range of firing dynamics of hippocampal networks.
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10
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Lang M, Moradi-Chameh H, Zahid T, Gane J, Wu C, Valiante T, Zhang L. Regulating hippocampal hyperexcitability through GABAB Receptors. Physiol Rep 2014. [PMID: 24771688 PMCID: PMC4001873 DOI: 10.1002/phy2.278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Disturbances of GABAergic inhibition are a major cause of epileptic seizures. GABA exerts its actions via ionotropic GABAA receptors and metabotropic G protein‐coupled GABAB receptors. Malfunction of GABAA inhibition has long been recognized in seizure genesis but the role of GABAB receptors in controlling seizure activity is still not well understood. Here, we examined the anticonvulsive, or inhibitory effects, of GABAB receptors in a mouse model of hippocampal kindling as well as mouse hippocampal slices through the use of GS 39783, a positive allosteric GABAB receptor modulator, and CGP 55845, a selective GABAB receptor antagonist. When administered via intraperitoneal injections in kindled mice, GS 39783 (5 mg/kg) did not attenuate hippocampal EEG discharges, but did reduce aberrant hippocampal spikes, whereas CGP 55845 (10 mg/kg) prolonged hippocampal discharges and increased spike incidences. When examined in hippocampal slices, neither GS 39783 at 5 μmol/L nor the GABAB receptor agonist baclofen at 0.1 μmol/L alone significantly altered repetitive excitatory field potentials, but GS 39783 and baclofen together reversibly abolished these field potentials. In contrast, CGP 55845 at 1 μmol/L facilitated induction and incidence of these field potentials. In addition, CGP 55845 attenuated the paired pulse depression of CA3 population spikes and increased the frequency of EPSCs in individual CA3 pyramidal neurons. Collectively, these data suggest that GABABB receptors regulate hippocampal hyperexcitability by inhibiting CA3 glutamatergic synapses. We postulate that positive allosteric modulation of GABAB receptors may be effective in reducing seizure‐related hyperexcitability. GABAB positive modulator GS 39783 attenuated, whereas GABAB antagonist CGP55845 facilitated hippocampal EEG spikes in kindled mice and excitatory field potentials in hippocampal slices. We postulate that GABAB receptors may inhibit CA3 glutamate synapses and hence regulate hippocampal hyperexcitability.
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Affiliation(s)
- Min Lang
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Homeira Moradi-Chameh
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
- Department of Physiology; University of Tarbiat Modares; Tehran Iran
| | - Tariq Zahid
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Jonathan Gane
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Chiping Wu
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Taufik Valiante
- Department of Surgery (Division of Neurosurgery); University of Toronto; Toronto Ontario Canada
| | - Liang Zhang
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
- Department of Medicine (Division of Neurology); University of Toronto; Toronto Ontario Canada
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11
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Masino SA, Kawamura M, Ruskin DN. Adenosine receptors and epilepsy: current evidence and future potential. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 119:233-55. [PMID: 25175969 PMCID: PMC6026023 DOI: 10.1016/b978-0-12-801022-8.00011-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Adenosine receptors are a powerful therapeutic target for regulating epileptic seizures. As a homeostatic bioenergetic network regulator, adenosine is perfectly suited to establish or restore an ongoing balance between excitation and inhibition, and its anticonvulsant efficacy is well established. There is evidence for the involvement of multiple adenosine receptor subtypes in epilepsy, but in particular the adenosine A1 receptor subtype can powerfully and bidirectionally regulate seizure activity. Mechanisms that regulate adenosine itself are increasingly appreciated as targets to thus influence receptor activity and seizure propensity. Taken together, established evidence for the powerful potential of adenosine-based epilepsy therapies and new strategies to influence receptor activity can combine to capitalize on this endogenous homeostatic neuromodulator.
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Affiliation(s)
- Susan A Masino
- Department of Psychology and Neuroscience Program, Trinity College, Hartford, Connecticut, USA.
| | - Masahito Kawamura
- Department of Pharmacology, Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - David N Ruskin
- Department of Psychology and Neuroscience Program, Trinity College, Hartford, Connecticut, USA
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12
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Taha AY, Zahid T, Epps T, Trepanier MO, Burnham W, Bazinet RP, Zhang L. Selective reduction of excitatory hippocampal sharp waves by docosahexaenoic acid and its methyl ester analog ex-vivo. Brain Res 2013; 1537:9-17. [DOI: 10.1016/j.brainres.2013.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 12/19/2022]
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13
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Hippocampal excitability is increased in aged mice. Exp Neurol 2013; 247:710-9. [PMID: 23510762 DOI: 10.1016/j.expneurol.2013.03.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/05/2013] [Accepted: 03/08/2013] [Indexed: 12/22/2022]
Abstract
Aging is known to be associated with a high risk of developing seizure disorders. Currently, the mechanisms underlying this increased seizure susceptibility are not fully understood. Several previous studies have shown a loss of subgroups of GABAergic inhibitory interneurons in the hippocampus of aged rodents, yet the network excitability intrinsic to the aged hippocampus remains to be elucidated. The aim of this study is to examine age-dependent changes of hippocampal network activities in young adult (3-5 months), aging (16-18 months), and aged (24-28 months) mice. We conducted intracranial electroencephalographic (EEG) recordings in free-moving animals and extracellular recordings in hippocampal slices in vitro. EEG recordings revealed frequent spikes in aging and aged mice but only occasionally in young adults. These EEG spikes were suppressed following diazepam administration. Spontaneous field potentials with large amplitudes were frequently observed in hippocampal slices of aged mice but rarely in slices from young adults. These spontaneous field potentials originated from the CA3 area and their generation was dependent upon the excitatory glutamatergic activity. We therefore postulate that hippocampal network excitability is increased in aged mice and that such hyperactivity may be relevant to the increased seizure susceptibility observed in aged subjects.
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14
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Inhibitory networks of fast-spiking interneurons generate slow population activities due to excitatory fluctuations and network multistability. J Neurosci 2012; 32:9931-46. [PMID: 22815508 DOI: 10.1523/jneurosci.5446-11.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Slow population activities (SPAs) exist in the brain and have frequencies below ~5 Hz. Despite SPAs being prominent in several cortical areas and serving many putative functions, their mechanisms are not well understood. We studied a specific type of in vitro GABAergic, inhibition-based SPA exhibited by C57BL/6 murine hippocampus. We used a multipronged approach consisting of experiment, simulation, and mathematical analyses to uncover mechanisms responsible for hippocampal SPAs. Our results show that hippocampal SPAs are an emergent phenomenon in which the "slowness" of the network is due to interactions between synaptic and cellular characteristics of individual fast-spiking, inhibitory interneurons. Our simulations quantify characteristics underlying hippocampal SPAs. In particular, for hippocampal SPAs to occur, we predict that individual fast-spiking interneurons should have frequency-current (f-I) curves that exhibit a suitably sized kink where the slope of the curve decreases more abruptly in the gamma frequency range with increasing current. We also predict that these interneurons should be well connected with one another. Our mathematical analyses show that the combination of synaptic and intrinsic conditions, as predicted by our simulations, promotes network multistability. Population slow timescales occur when excitatory fluctuations drive the network between different stable network firing states. Since many of the parameters we use are extracted from experiments and subsequent measurements of experimental f-I curves of fast-spiking interneurons exhibit characteristics as predicted, we propose that our network models capture a fundamental operating mechanism in biological hippocampal networks.
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Mauleon G, Fall CP, Eddington DT. Precise spatial and temporal control of oxygen within in vitro brain slices via microfluidic gas channels. PLoS One 2012; 7:e43309. [PMID: 22905255 PMCID: PMC3419219 DOI: 10.1371/journal.pone.0043309] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 07/19/2012] [Indexed: 11/18/2022] Open
Abstract
The acute brain slice preparation is an excellent model for studying the details of how neurons and neuronal tissue respond to a variety of different physiological conditions. But open slice chambers ideal for electrophysiological and imaging access have not allowed the precise spatiotemporal control of oxygen in a way that might realistically model stroke conditions. To address this problem, we have developed a microfluidic add-on to a commercially available perfusion chamber that diffuses oxygen throughout a thin membrane and directly to the brain slice. A microchannel enables rapid and efficient control of oxygen and can be modified to allow different regions of the slice to experience different oxygen conditions. Using this novel device, we show that we can obtain a stable and homogeneous oxygen environment throughout the brain slice and rapidly alter the oxygen tension in a hippocampal slice. We also show that we can impose different oxygen tensions on different regions of the slice preparation and measure two independent responses, which is not easily obtainable with current techniques.
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Affiliation(s)
- Gerardo Mauleon
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Christopher P. Fall
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
- Department of Computer Science, Georgetown University, Georgetown, Washington, D. C., United States of America
| | - David T. Eddington
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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16
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Network bursting using experimentally constrained single compartment CA3 hippocampal neuron models with adaptation. J Comput Neurosci 2011; 33:21-40. [DOI: 10.1007/s10827-011-0372-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 10/23/2011] [Accepted: 11/02/2011] [Indexed: 11/26/2022]
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Abstract
Clinical evidence, in particular the wide use of theophylline as a bronchodilator, suggests that methylxanthines can cause seizures in patients without known underlying epilepsy. Theophylline is also known to be an added risk factor for seizure exacerbation in patients with epilepsy. The proconvulsant activity of methylxanthines can best be explained by their antagonizing the brain's own anticonvulsant adenosine. Recent evidence suggests that adenosine dysfunction is a pathological hallmark of epilepsy contributing to seizure generation and seizure spread. Conversely, adenosine augmentation therapies are effective in seizure suppression and prevention, whereas adenosine receptor antagonists such as methylxanthines generally exacerbate seizures. The impact of the methylxanthines caffeine and theophylline on seizures and excitotoxicity depends on timing, dose, and acute versus chronic use. New findings suggest a role of free radicals in theophylline-induced seizures, and adenosine-independent mechanisms for seizure generation have been proposed.
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Affiliation(s)
- Detlev Boison
- R.S. Dow Neurobiology Laboratories, Legacy Research, Portland, OR 97232, USA
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18
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Patterned activation of hippocampal network (∼10 Hz) during in vitro sharp wave-ripples. Neuroscience 2010; 168:429-42. [DOI: 10.1016/j.neuroscience.2010.03.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/22/2010] [Accepted: 03/27/2010] [Indexed: 11/15/2022]
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An approach for reliably investigating hippocampal sharp wave-ripples in vitro. PLoS One 2009; 4:e6925. [PMID: 19738897 PMCID: PMC2732900 DOI: 10.1371/journal.pone.0006925] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 07/17/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Among the various hippocampal network patterns, sharp wave-ripples (SPW-R) are currently the mechanistically least understood. Although accurate information on synaptic interactions between the participating neurons is essential for comprehensive understanding of the network function during complex activities like SPW-R, such knowledge is currently notably scarce. METHODOLOGY/PRINCIPAL FINDINGS We demonstrate an in vitro approach to SPW-R that offers a simple experimental tool allowing detailed analysis of mechanisms governing the sharp wave-state of the hippocampus. We combine interface storage of slices with modifications of a conventional submerged recording system and established in vitro SPW-R comparable to their in vivo counterpart. We show that slice storage in the interface chamber close to physiological temperature is the required condition to preserve network integrity that is necessary for the generation of SPW-R. Moreover, we demonstrate the utility of our method for studying synaptic and network properties of SPW-R, using electrophysiological and imaging methods that can only be applied in the submerged system. CONCLUSIONS/SIGNIFICANCE The approach presented here demonstrates a reliable and experimentally simple strategy for studying hippocampal sharp wave-ripples. Given its utility and easy application we expect our model to foster the generation of new insight into the network physiology underlying SPW-R.
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Beenhakker MP, Huguenard JR. Neurons that fire together also conspire together: is normal sleep circuitry hijacked to generate epilepsy? Neuron 2009; 62:612-32. [PMID: 19524522 PMCID: PMC2748990 DOI: 10.1016/j.neuron.2009.05.015] [Citation(s) in RCA: 265] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 05/15/2009] [Accepted: 05/18/2009] [Indexed: 02/02/2023]
Abstract
Brain circuits oscillate during sleep. The same circuits appear to generate pathological oscillations. In this review, we discuss recent advances in our understanding of how epilepsy co-opts normal, sleep-related circuits to generate seizures.
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Affiliation(s)
- Mark P Beenhakker
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
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21
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Repeated hypoxic episodes induce seizures and alter hippocampal network activities in mice. Neuroscience 2009; 161:599-613. [DOI: 10.1016/j.neuroscience.2009.03.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 02/08/2009] [Accepted: 03/15/2009] [Indexed: 11/23/2022]
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