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Nasretdinov A, Jappy D, Vazetdinova A, Valiullina-Rakhmatullina F, Rozov A. Acute stress modulates hippocampal to entorhinal cortex communication. Front Cell Neurosci 2023; 17:1327909. [PMID: 38145281 PMCID: PMC10740169 DOI: 10.3389/fncel.2023.1327909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 11/24/2023] [Indexed: 12/26/2023] Open
Abstract
Feed-forward inhibition is vital in the transfer and processing of synaptic information within the hippocampal-entorhinal loop by controlling the strength and direction of excitation flow between different neuronal populations and individual neurons. While the cellular targets in the hippocampus that receive excitatory inputs from the entorhinal cortex have been well studied, and the role of feedforward inhibitory neurons has been attributed to neurogliafom cells, the cortical interneurons providing feed-forward control over receiving layer V in the entorhinal cortex remain unknown. We used sharp-wave ripple oscillations as a natural excitatory stimulus of the entorhinal cortex, driven by the hippocampus, to study the function of synaptic interactions between neurons in the deep layers of the entorhinal cortex. We discovered that CB1R-expressing interneurons in the deep layers of the entorhinal cortex constitute the major relay station that translates hippocampal excitation into efficient inhibition of cortical pyramidal cells. The impact of inhibition provided by these interneurons is under strong endocannabinoid control and can be drastically reduced either by enhanced activity of postsynaptic targets or by stress-induced elevation of cannabinoids.
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Affiliation(s)
- Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - David Jappy
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
- Institute of Neuroscience, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Alina Vazetdinova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - Fliza Valiullina-Rakhmatullina
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - Andrei Rozov
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
- Department of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
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Chen L, Wick ZC, Vetere LM, Vaughan N, Jurkowski A, Galas A, Diego KS, Philipsberg P, Cai DJ, Shuman T. Progressive excitability changes in the medial entorhinal cortex in the 3xTg mouse model of Alzheimer's disease pathology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542838. [PMID: 37398359 PMCID: PMC10312508 DOI: 10.1101/2023.05.30.542838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative disorder that is characterized by memory loss and progressive cognitive impairments. In mouse models of AD pathology, studies have found neuronal and synaptic deficits in the hippocampus, but less is known about what happens in the medial entorhinal cortex (MEC), which is the primary spatial input to the hippocampus and an early site of AD pathology. Here, we measured the neuronal intrinsic excitability and synaptic activity in MEC layer II (MECII) stellate cells, MECII pyramidal cells, and MEC layer III (MECIII) excitatory neurons at early (3 months) and late (10 months) time points in the 3xTg mouse model of AD pathology. At 3 months of age, prior to the onset of memory impairments, we found early hyperexcitability in MECII stellate and pyramidal cells' intrinsic properties, but this was balanced by a relative reduction in synaptic excitation (E) compared to inhibition (I), suggesting intact homeostatic mechanisms regulating activity in MECII. Conversely, MECIII neurons had reduced intrinsic excitability at this early time point with no change in the synaptic E/I ratio. By 10 months of age, after the onset of memory deficits, neuronal excitability of MECII pyramidal cells and MECIII excitatory neurons was largely normalized in 3xTg mice. However, MECII stellate cells remained hyperexcitable and this was further exacerbated by an increased synaptic E/I ratio. This observed combination of increased intrinsically and synaptically generated excitability suggests a breakdown in homeostatic mechanisms specifically in MECII stellate cells at this post-symptomatic time point. Together, these data suggest that the breakdown in homeostatic excitability mechanisms in MECII stellate cells may contribute to the emergence of memory deficits in AD.
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Affiliation(s)
- Lingxuan Chen
- Icahn School of Medicine at Mount Sinai, New York NY
- University of California Irvine, Irvine CA
| | | | | | - Nick Vaughan
- Icahn School of Medicine at Mount Sinai, New York NY
| | - Albert Jurkowski
- Icahn School of Medicine at Mount Sinai, New York NY
- CUNY Hunter College, New York NY
| | - Angelina Galas
- Icahn School of Medicine at Mount Sinai, New York NY
- New York University, New York NY
| | | | | | - Denise J. Cai
- Icahn School of Medicine at Mount Sinai, New York NY
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Scalmani P, Paterra R, Mantegazza M, Avoli M, de Curtis M. Involvement of GABAergic Interneuron Subtypes in 4-Aminopyridine-Induced Seizure-Like Events in Mouse Entorhinal Cortex in Vitro. J Neurosci 2023; 43:1987-2001. [PMID: 36810229 PMCID: PMC10027059 DOI: 10.1523/jneurosci.1190-22.2023] [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: 06/17/2022] [Revised: 12/30/2022] [Accepted: 01/05/2023] [Indexed: 02/23/2023] Open
Abstract
Single-unit recordings performed in temporal lobe epilepsy patients and in models of temporal lobe seizures have shown that interneurons are active at focal seizure onset. We performed simultaneous patch-clamp and field potential recordings in entorhinal cortex slices of GAD65 and GAD67 C57BL/6J male mice that express green fluorescent protein in GABAergic neurons to analyze the activity of specific interneuron (IN) subpopulations during acute seizure-like events (SLEs) induced by 4-aminopyridine (4-AP; 100 μm). IN subtypes were identified as parvalbuminergic (INPV, n = 17), cholecystokinergic (INCCK), n = 13], and somatostatinergic (INSOM, n = 15), according to neurophysiological features and single-cell digital PCR. INPV and INCCK discharged at the start of 4-AP-induced SLEs characterized by either low-voltage fast or hyper-synchronous onset pattern. In both SLE onset types, INSOM fired earliest before SLEs, followed by INPV and INCCK discharges. Pyramidal neurons became active with variable delays after SLE onset. Depolarizing block was observed in ∼50% of cells in each INs subgroup, and it was longer in IN (∼4 s) than in pyramidal neurons (<1 s). As SLE evolved, all IN subtypes generated action potential bursts synchronous with the field potential events leading to SLE termination. High-frequency firing throughout the SLE occurred in one-third of INPV and INSOM We conclude that entorhinal cortex INs are very active at the onset and during the progression of SLEs induced by 4-AP. These results support earlier in vivo and in vivo evidence and suggest that INs have a preferential role in focal seizure initiation and development.SIGNIFICANCE STATEMENT Focal seizures are believed to result from enhanced excitation. Nevertheless, we and others demonstrated that cortical GABAergic networks may initiate focal seizures. Here, we analyzed for the first time the role of different IN subtypes in seizures generated by 4-aminopyridine in the mouse entorhinal cortex slices. We found that in this in vitro focal seizure model, all IN types contribute to seizure initiation and that INs precede firing of principal cells. This evidence is in agreement with the active role of GABAergic networks in seizure generation.
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Affiliation(s)
| | - Rosina Paterra
- Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano 20133, Italy
| | - Massimo Mantegazza
- Université Côte d'Azur, 06560 Valbonne-Sophia Antipolis, France
- Institute of Molecular and Cellular Pharmacology, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7275, Laboratoire d'Excellence/Canaux Ioniques d'Intérêt Thérapeutique, 06650 Valbonne-Sophia Antipolis, France
- Institut National de la Santé et de la Recherche Médicale, 06650 Valbonne-Sophia Antipolis, France
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Quebec H3A 2B4, Canada
- Departments of Neurology and Neurosurgery and Physiology, McGill University, Montreal, Quebec H3A 2B4, Canada
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Cell-Type Specific Inhibition Controls the High-Frequency Oscillations in the Medial Entorhinal Cortex. Int J Mol Sci 2022; 23:ijms232214087. [PMID: 36430563 PMCID: PMC9696652 DOI: 10.3390/ijms232214087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/04/2022] [Accepted: 11/06/2022] [Indexed: 11/17/2022] Open
Abstract
The medial entorhinal cortex (mEC) plays a critical role for spatial navigation and memory. While many studies have investigated the principal neurons within the entorhinal cortex, much less is known about the inhibitory circuitries within this structure. Here, we describe for the first time in the mEC a subset of parvalbumin-positive (PV+) interneurons (INs)-stuttering cells (STUT)-with morphological, intrinsic electrophysiological, and synaptic properties distinct from fast-spiking PV+ INs. In contrast to the fast-spiking PV+ INs, the axon of the STUT INs also terminated in layer 3 and showed subthreshold membrane oscillations at gamma frequencies. Whereas the synaptic output of the STUT INs was only weakly reduced by a μ-opioid agonist, their inhibitory inputs were strongly suppressed. Given these properties, STUT are ideally suited to entrain gamma activity in the pyramidal cell population of the mEC. We propose that activation of the μ-opioid receptors decreases the GABA release from the PV+ INs onto the STUT, resulting in disinhibition of the STUT cell population and the consequent increase in network gamma power. We therefore suggest that the opioid system plays a critical role, mediated by STUT INs, in the neural signaling and oscillatory network activity within the mEC.
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Baccini G, Wulff P. Commentary on: Peng, Y et al., Structured recurrent inhibition in the presubiculum could improve information processing. Pflugers Arch 2021; 473:1691-1693. [PMID: 34648053 PMCID: PMC8528764 DOI: 10.1007/s00424-021-02626-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 09/13/2021] [Accepted: 09/17/2021] [Indexed: 11/25/2022]
Affiliation(s)
- Gilda Baccini
- Institute of Physiology, Christian-Albrechts-University Kiel, 24098, Kiel, Germany.
| | - Peer Wulff
- Institute of Physiology, Christian-Albrechts-University Kiel, 24098, Kiel, Germany.
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Tukker JJ, Beed P, Brecht M, Kempter R, Moser EI, Schmitz D. Microcircuits for spatial coding in the medial entorhinal cortex. Physiol Rev 2021; 102:653-688. [PMID: 34254836 PMCID: PMC8759973 DOI: 10.1152/physrev.00042.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The hippocampal formation is critically involved in learning and memory and contains a large proportion of neurons encoding aspects of the organism’s spatial surroundings. In the medial entorhinal cortex (MEC), this includes grid cells with their distinctive hexagonal firing fields as well as a host of other functionally defined cell types including head direction cells, speed cells, border cells, and object-vector cells. Such spatial coding emerges from the processing of external inputs by local microcircuits. However, it remains unclear exactly how local microcircuits and their dynamics within the MEC contribute to spatial discharge patterns. In this review we focus on recent investigations of intrinsic MEC connectivity, which have started to describe and quantify both excitatory and inhibitory wiring in the superficial layers of the MEC. Although the picture is far from complete, it appears that these layers contain robust recurrent connectivity that could sustain the attractor dynamics posited to underlie grid pattern formation. These findings pave the way to a deeper understanding of the mechanisms underlying spatial navigation and memory.
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Affiliation(s)
- John J Tukker
- Network Dysfunction, German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Prateep Beed
- NeuroScientific Research Center, Charite Berlin, Germany
| | - Michael Brecht
- Systems Neuroscience, Humboldt University of Berlin, Berlin, Germany
| | - Richard Kempter
- Department of Biology, Institute for Theoretical Biology, Humbolt-Universität zu Berlin, Berlin, Germany
| | - Edvard I Moser
- Kavli Institute for Systems Neuroscience and Centre for the Biology of Memory, Norwegian University of Science and Technology
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
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An inventory of basic research in temporal lobe epilepsy. Rev Neurol (Paris) 2021; 177:1069-1081. [PMID: 34176659 DOI: 10.1016/j.neurol.2021.02.390] [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: 12/03/2020] [Revised: 01/26/2021] [Accepted: 02/05/2021] [Indexed: 12/25/2022]
Abstract
Temporal lobe epilepsy is a severe neurological disease, characterized by seizure occurrence and invalidating cognitive co-morbidities, which affects up to 1% of the adults. Roughly one third of the patients are resistant to any conventional pharmacological treatments. The last option in that case is the surgical removal of the epileptic focus, with no guarantee for clinical symptom alleviation. This state of affairs requests the identification of cellular or molecular targets for novel therapeutic approaches with limited side effects. Here we review some generalities about the disease as well as some of the most recent discoveries about the cellular and molecular mechanisms of TLE, and the latest perspectives for novel treatments.
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Kang YJ, Clement EM, Park IH, Greenfield LJ, Smith BN, Lee SH. Vulnerability of cholecystokinin-expressing GABAergic interneurons in the unilateral intrahippocampal kainate mouse model of temporal lobe epilepsy. Exp Neurol 2021; 342:113724. [PMID: 33915166 DOI: 10.1016/j.expneurol.2021.113724] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/26/2021] [Accepted: 04/22/2021] [Indexed: 10/21/2022]
Abstract
Temporal lobe epilepsy (TLE) is characterized by recurrent spontaneous seizures and behavioral comorbidities. Reduced hippocampal theta oscillations and hyperexcitability that contribute to cognitive deficits and spontaneous seizures are present beyond the sclerotic hippocampus in TLE. However, the mechanisms underlying compromised network oscillations and hyperexcitability observed in circuits remote from the sclerotic hippocampus are largely unknown. Cholecystokinin (CCK)-expressing basket cells (CCKBCs) critically participate in hippocampal theta rhythmogenesis, and regulate neuronal excitability. Thus, we examined whether CCKBCs were vulnerable in nonsclerotic regions of the ventral hippocampus remote from dorsal sclerotic hippocampus using the intrahippocampal kainate (IHK) mouse model of TLE, targeting unilateral dorsal hippocampus. We found a decrease in the number of CCK+ interneurons in ipsilateral ventral CA1 regions from epileptic mice compared to those from sham controls. We also found that the number of boutons from CCK+ interneurons was reduced in the stratum pyramidale, but not in other CA1 layers, of ipsilateral hippocampus in epileptic mice, suggesting that CCKBCs are vulnerable. Electrical recordings showed that synaptic connectivity and strength from surviving CCKBCs to CA1 pyramidal cells (PCs) were similar between epileptic mice and sham controls. In agreement with reduced CCKBC number in TLE, electrical recordings revealed a significant reduction in amplitude and frequency of IPSCs in CA1 PCs evoked by carbachol (commonly used to excite CCK+ interneurons) in ventral CA1 regions from epileptic mice versus sham controls. These findings suggest that loss of CCKBCs beyond the hippocampal lesion may contribute to hyperexcitability and compromised network oscillations in TLE.
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Affiliation(s)
- Young-Jin Kang
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA; Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Ethan M Clement
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale Child Study Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Lazar John Greenfield
- Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Bret N Smith
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA
| | - Sang-Hun Lee
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA; Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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9
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Development and Arealization of the Cerebral Cortex. Neuron 2019; 103:980-1004. [DOI: 10.1016/j.neuron.2019.07.009] [Citation(s) in RCA: 145] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/15/2019] [Accepted: 07/03/2019] [Indexed: 12/16/2022]
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10
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Farrell JS, Nguyen QA, Soltesz I. Resolving the Micro-Macro Disconnect to Address Core Features of Seizure Networks. Neuron 2019; 101:1016-1028. [PMID: 30897354 PMCID: PMC6430140 DOI: 10.1016/j.neuron.2019.01.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/14/2018] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
Current drug treatments for epilepsy attempt to broadly restrict excitability to mask a symptom, seizures, with little regard for the heterogeneous mechanisms that underlie disease manifestation across individuals. Here, we discuss the need for a more complete view of epilepsy, outlining how key features at the cellular and microcircuit level can significantly impact disease mechanisms that are not captured by the most common methodology to study epilepsy, electroencephalography (EEG). We highlight how major advances in neuroscience tool development now enable multi-scale investigation of fundamental questions to resolve the currently controversial understanding of seizure networks. These findings will provide essential insight into what has emerged as a disconnect between the different levels of investigation and identify new targets and treatment options.
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Affiliation(s)
- Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Quynh-Anh Nguyen
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
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11
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Yu D, Xiao R, Huang J, Cai Y, Bao X, Jing S, Du Z, Yang T, Fan X. Neonatal exposure to propofol affects interneuron development in the piriform cortex and causes neurobehavioral deficits in adult mice. Psychopharmacology (Berl) 2019; 236:657-670. [PMID: 30415279 DOI: 10.1007/s00213-018-5092-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 10/25/2018] [Indexed: 11/24/2022]
Abstract
RATIONALE Animal studies have shown that early postnatal propofol administration is involved in neurobehavioral alterations in adults. However, the underlying mechanism is not clear. METHODS We used c-Fos immunohistochemistry to identify activated neurons in brain regions of neonatal mice under propofol exposure and performed behavioral tests to observe the long-term consequences. RESULTS Exposure to propofol (30g or 60 mg/kg) on P7 produced significant c-Fos expression in the deep layers of the piriform cortex on P8. Double immunofluorescence of c-Fos with interneuron markers in the piriform cortex revealed that c-Fos was specifically induced in calbindin (CB)-positive interneurons. Repeated propofol exposure from P7 to P9 induced behavioral deficits in adult mice, such as olfactory function deficit in a buried food test, decreased sociability in a three-chambered choice task, and impaired recognitive ability of learning and memory in novel object recognition tests. However, locomotor activity in the open-field test was not generally affected. Propofol treatment also significantly decreased the number of CB-positive interneurons in the piriform cortex of mice on P21 and adulthood. CONCLUSIONS These results suggest that CB-positive interneurons in the piriform cortex are vulnerable to propofol exposure during the neonatal period, and these neurons are involved in the damage effects of propofol on behavior changes. These data provide a new target of propofol neurotoxicity and may elucidate the mechanism of neurobehavioral deficits in adulthood.
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Affiliation(s)
- Dan Yu
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China.,Department of Anesthesiology, Wuhan No.4 Hospital, Wuhan Puai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430033, People's Republic of China
| | - Rui Xiao
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China.,Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Jing Huang
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Yulong Cai
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Xiaohang Bao
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China.,Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Sheng Jing
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Zhiyong Du
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China
| | - Tiande Yang
- Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400038, People's Republic of China.
| | - Xiaotang Fan
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, People's Republic of China.
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12
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Development of Parvalbumin-Expressing Basket Terminals in Layer II of the Rat Medial Entorhinal Cortex. eNeuro 2018; 5:eN-NWR-0438-17. [PMID: 29951577 PMCID: PMC6019390 DOI: 10.1523/eneuro.0438-17.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/06/2018] [Accepted: 05/08/2018] [Indexed: 11/21/2022] Open
Abstract
Grid cells in layer II of the medial entorhinal cortex (MEC LII) generate multiple regular firing fields in response to the position and speed of an individual within the environment. They exhibit a protracted postnatal development and, in the adult, show activity differences along the dorsoventral axis (DVA). Evidence suggests parvalbumin-positive (PV+) interneurons, most of which are perisomatic-targeting cells, play a crucial role in generation of the hexagonal grid cell activity pattern. We therefore hypothesized that the development and organization of PV+ perisomatic terminals in MEC LII reflect the postnatal emergence of the hexagonal firing pattern and dorsoventral differences seen in grid cell activity. We used immuno-electron microscopy to examine the development of PV+ perisomatic terminals and their target somata within dorsal and ventral MEC LII in rats of postnatal day (P)10, P15, and P30. We demonstrate that in dorsal and ventral MEC LII, the cross-sectional area of somata and number and density of perisomatic PV+ terminals increase between P10 and P15. A simultaneous decrease was observed in cross-sectional area of PV+ terminals. Between P15 and P30, both MEC regions showed an increase in PV+ terminal size and percentage of PV+ terminals containing mitochondria, which may enable grid cell activity to emerge and stabilize. We also report that dorsal somata are larger and apposed by more PV+ terminals than ventral somata at all stages, suggesting a protracted maturation in the ventral portion and a possible gradient in soma size and PV+ basket innervation along the DVA in the adult.
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13
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Berggaard N, Seifi M, van der Want JJL, Swinny JD. Spatiotemporal Distribution of GABA A Receptor Subunits Within Layer II of Mouse Medial Entorhinal Cortex: Implications for Grid Cell Excitability. Front Neuroanat 2018; 12:46. [PMID: 29915531 PMCID: PMC5994561 DOI: 10.3389/fnana.2018.00046] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/18/2018] [Indexed: 11/13/2022] Open
Abstract
GABAergic parvalbumin-expressing (PV+) interneurons provide powerful inhibitory modulation of grid cells in layer II of the medial entorhinal cortex (MEC LII). However, the molecular machinery through which PV+ cells regulate grid cell activity is poorly defined. PV+ interneurons impart inhibitory modulation primarily via GABA-A receptors (GABAARs). GABAARs are pentameric ion channels assembled from a repertoire of 19 subunits. Multiple subunit combinations result in a variety of receptor subtypes mediating functionally diverse postsynaptic inhibitory currents. Whilst the broad expression patterns of GABAAR subunits within the EC have been reported, those expressed by individual MEC LII cell types, in particular grid cells candidates, stellate and pyramidal cells, are less well described. Stellate and pyramidal cells are distinguished by their selective expression of reelin (RE+) and calbindin (CB+) respectively. Thus, the overall aim of this study was to provide a high resolution analysis of the major (α and γ) GABAAR subunits expressed in proximity to somato-dendritic PV+ boutons, on RE+ and CB+ cells, using immunohistochemistry, confocal microscopy and quantitative RT-PCR (qPCR). Clusters immunoreactive for the α1 and γ2 subunits decorated the somatic membranes of both RE+ and CB+ cells and were predominantly located in apposition to clusters immunoreactive for PV and vesicular GABA transporter (VGAT), suggesting expression in GABAergic synapses innervated by PV interneurons. Although intense α2 subunit-immunopositive clusters were evident in hippocampal fields located in close proximity to the EC, no specific signal was detected in MEC LII RE+ and CB+ profiles. Immunoreactivity for the α3 subunit was detected in all RE+ somata. In contrast, only a sub-population of CB+ cells was α3 immunopositive. These included CB-α3 cells which were both PV+ and PV-. Furthermore, α3 subunit mRNA and immunofluorescence decreased significantly between P 15 and P 25, a period implicated in the functional maturation of grid cells. Finally, α5 subunit immunoreactivity was detectable only on CB+ cells, not on RE+ cells. The present data demonstrates that physiologically distinct GABAAR subtypes are selectively expressed by CB+ and RE+ cells. This suggests that PV+ interneurons could utilize distinct postsynaptic signaling mechanisms to regulate the excitability of these different, candidate grid cell sub-populations.
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Affiliation(s)
- Nina Berggaard
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mohsen Seifi
- Institute for Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Johannes J L van der Want
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jerome D Swinny
- Institute for Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
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14
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Kang YJ, Lewis HES, Young MW, Govindaiah G, Greenfield LJ, Garcia-Rill E, Lee SH. Cell Type-specific Intrinsic Perithreshold Oscillations in Hippocampal GABAergic Interneurons. Neuroscience 2018; 376:80-93. [PMID: 29462702 PMCID: PMC5978001 DOI: 10.1016/j.neuroscience.2018.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 02/08/2018] [Accepted: 02/09/2018] [Indexed: 01/01/2023]
Abstract
The hippocampus plays a critical role in learning, memory, and spatial processing through coordinated network activity including theta and gamma oscillations. Recent evidence suggests that hippocampal subregions (e.g., CA1) can generate these oscillations at the network level, at least in part, through GABAergic interneurons. However, it is unclear whether specific GABAergic interneurons generate intrinsic theta and/or gamma oscillations at the single-cell level. Since major types of CA1 interneurons (i.e., parvalbumin-positive basket cells (PVBCs), cannabinoid type 1 receptor-positive basket cells (CB1BCs), Schaffer collateral-associated cells (SCAs), neurogliaform cells and ivy cells) are thought to play key roles in network theta and gamma oscillations in the hippocampus, we tested the hypothesis that these cells generate intrinsic perithreshold oscillations at the single-cell level. We performed whole-cell patch-clamp recordings from GABAergic interneurons in the CA1 region of the mouse hippocampus in the presence of synaptic blockers to identify intrinsic perithreshold membrane potential oscillations. The majority of PVBCs (83%), but not the other interneuron subtypes, produced intrinsic perithreshold gamma oscillations if the membrane potential remained above -45 mV. In contrast, CB1BCs, SCAs, neurogliaform cells, ivy cells, and the remaining PVBCs (17%) produced intrinsic theta, but not gamma, oscillations. These oscillations were prevented by blockers of persistent sodium current. These data demonstrate that the major types of hippocampal interneurons produce distinct frequency bands of intrinsic perithreshold membrane oscillations.
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Affiliation(s)
- Young-Jin Kang
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | | | - Mason William Young
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Gubbi Govindaiah
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Lazar John Greenfield
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Sang-Hun Lee
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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15
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Naumann RK, Preston-Ferrer P, Brecht M, Burgalossi A. Structural modularity and grid activity in the medial entorhinal cortex. J Neurophysiol 2018. [PMID: 29513150 DOI: 10.1152/jn.00574.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Following the groundbreaking discovery of grid cells, the medial entorhinal cortex (MEC) has become the focus of intense anatomical, physiological, and computational investigations. Whether and how grid activity maps onto cell types and cortical architecture is still an open question. Fundamental similarities in microcircuits, function, and connectivity suggest a homology between rodent MEC and human posteromedial entorhinal cortex. Both are specialized for spatial processing and display similar cellular organization, consisting of layer 2 pyramidal/calbindin cell patches superimposed on scattered stellate neurons. Recent data indicate the existence of a further nonoverlapping modular system (zinc patches) within the superficial MEC layers. Zinc and calbindin patches have been shown to receive largely segregated inputs from the presubiculum and parasubiculum. Grid cells are also clustered in the MEC, and we discuss possible structure-function schemes on how grid activity could map onto cortical patch systems. We hypothesize that in the superficial layers of the MEC, anatomical location can be predictive of function; thus relating functional properties and neuronal morphologies to the cortical modules will be necessary for resolving how grid activity maps onto cortical architecture. Imaging or cell identification approaches in freely moving animals will be required for testing this hypothesis.
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Affiliation(s)
- Robert K Naumann
- Bernstein Center for Computational Neuroscience, Humboldt University of Berlin , Berlin , Germany.,Max-Planck-Institute for Brain Research, Frankfurt am Main , Germany.,Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen University Town, Nanshan District, Shenzhen , China
| | | | - Michael Brecht
- Bernstein Center for Computational Neuroscience, Humboldt University of Berlin , Berlin , Germany.,German Center for Neurodegenerative Diseases , Berlin , Germany
| | - Andrea Burgalossi
- Werner-Reichardt Centre for Integrative Neuroscience , Tübingen , Germany
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16
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Sultan KT, Shi SH. Generation of diverse cortical inhibitory interneurons. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2018; 7:10.1002/wdev.306. [PMID: 29115042 PMCID: PMC5814332 DOI: 10.1002/wdev.306] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 12/16/2022]
Abstract
First described by Ramon y Cajal as 'short-axon' cells over a century ago, inhibitory interneurons in the cerebral cortex make up ~20-30% of the neuronal milieu. A key feature of these interneurons is the striking structural and functional diversity, which allows them to modulate neural activity in diverse ways and ultimately endow neural circuits with remarkable computational power. Here, we review our current understanding of the generation of cortical interneurons, with a focus on recent efforts to bridge the gap between progenitor behavior and interneuron production, and how these aspects influence interneuron diversity and organization. WIREs Dev Biol 2018, 7:e306. doi: 10.1002/wdev.306 This article is categorized under: Nervous System Development > Vertebrates: General Principles.
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Affiliation(s)
- Khadeejah T Sultan
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Neuroscience Graduate Program, Weill Cornell Medical College, New York, NY, USA
| | - Song-Hai Shi
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Neuroscience Graduate Program, Weill Cornell Medical College, New York, NY, USA
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17
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Forcelli PA. Applications of optogenetic and chemogenetic methods to seizure circuits: Where to go next? J Neurosci Res 2017; 95:2345-2356. [PMID: 28791729 DOI: 10.1002/jnr.24135] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/05/2017] [Accepted: 07/14/2017] [Indexed: 01/02/2023]
Abstract
Epilepsy is the quintessential circuit disorder, with seizure activity propagating through anatomically constrained pathways. These pathways, necessary for normal sensory, motor, and cognitive function, are hijacked during seizures. Understanding the network architecture at the level of both local microcircuits and distributed macrocircuits may provide new therapeutic avenues for the treatment of epilepsy. Over the past decade, optogenetic and chemogenetic tools have enabled previously impossible levels of functional circuit mapping in neuroscience. In this review, examples of the application of optogenetics and chemogenetics to epilepsy are raised, the comparative strengths and weaknesses of these approaches are discussed for both preclinical and translational applications, and recent applications of these approaches in other areas of neuroscience are highlighted. These points are raised in an effort to highlight the potential of these methods to address additional unanswered questions in epilepsy.
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Affiliation(s)
- Patrick A Forcelli
- Department of Pharmacology & Physiology, Department of Neuroscience, and Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, DC
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18
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Sheilabi MA, Battacharyya D, Caetano L, Thom M, Reuber M, Duncan JS, Princivalle AP. Quantitative expression and localization of GABA B receptor protein subunits in hippocampi from patients with refractory temporal lobe epilepsy. Neuropharmacology 2017; 136:117-128. [PMID: 28782512 DOI: 10.1016/j.neuropharm.2017.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 01/03/2023]
Abstract
This study investigates GABAB protein expression and mRNA levels in three types of specimens. Two types of specimens from patients with temporal lobe epilepsy (TLE), secondary to hippocampal sclerosis, sclerotic hippocampal samples (TLE-HS), and tissue from the structurally preserved non-spiking ipsilateral superior temporal gyrus (TLE-STG) removed from the same patient during epilepsy surgery; and third specimen is hippocampal tissue from individuals with no history of epilepsy (post-mortem controls, PMC). mRNA expression of GABAB subunits was quantified in TLE-HS, TLE-STG and PMC specimens by qRT-PCR. Qualitative and quantitative Western blot (WB) and immunohistochemistry techniques were employed to quantify and localize GABAB proteins subunits. qRT-PCR data demonstrated an overall decrease of both GABAB1 isoforms in TLE-HS compared to TLE-STG. These results were mirrored by the WB findings. GABAB2 mRNA and protein were significantly reduced in TLE-HS samples compared to TLE-STG; however they appeared to be upregulated in TLE-HS compared to the PMC samples. Immunohistochemistry (IHC) showed that GABAB proteins were widely distributed in PMC and TLE-HS hippocampal sections with regional differences in the intensity of the signal. The higher expression of mature GABAB protein in TLE-HS than PMC is in agreement with previous studies. However, these findings could be due to post-mortem changes in PMC specimens. The TLE-STG samples examined here represent a better 'control' tissue compared to TLE-HS samples characterised by lower than expected GABAB expression. This interpretation provides a better explanation for previous functional studies suggesting reduced inhibition in TLE-HS tissue due to attenuated GABAB currents. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Mariam A Sheilabi
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
| | - Dev Battacharyya
- Neurosurgery, Sheffield Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK
| | - Laura Caetano
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
| | - Maria Thom
- Department of Neuropathology, Institute of Neurology, UCL, Queen Square, London, UK
| | - Markus Reuber
- Academic Neurology Unit, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, Queen Square, London, UK
| | - Alessandra P Princivalle
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK; Division of Neuroscience, Department of Pharmacology, Medical School, University of Birmingham, Birmingham, B15 2TT, UK.
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19
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Zhang XJ, Li Z, Han Z, Sultan KT, Huang K, Shi SH. Precise inhibitory microcircuit assembly of developmentally related neocortical interneurons in clusters. Nat Commun 2017; 8:16091. [PMID: 28703129 PMCID: PMC5511369 DOI: 10.1038/ncomms16091] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/26/2017] [Indexed: 12/11/2022] Open
Abstract
GABA-ergic interneurons provide diverse inhibitions that are essential for the operation of neuronal circuits in the neocortex. However, the mechanisms that control the functional organization of neocortical interneurons remain largely unknown. Here we show that developmental origins influence fine-scale synapse formation and microcircuit assembly of neocortical interneurons. Spatially clustered neocortical interneurons originating from low-titre retrovirus-infected radial glial progenitors in the embryonic medial ganglionic eminence and preoptic area preferentially develop electrical, but not chemical, synapses with each other. This lineage-related electrical coupling forms predominantly between the same interneuron subtype over an extended postnatal period and across a range of distances, and promotes action potential generation and synchronous firing. Interestingly, this selective electrical coupling relates to a coordinated inhibitory chemical synapse formation between sparsely labelled interneurons in clusters and the same nearby excitatory neurons. These results suggest a link between the lineage relationship of neocortical interneurons and their precise functional organization. Developmental neuroscientists have long asked if clonally-related neurons retain functional relationships after maturation. The authors show that sparsely labelled neocortical interneurons in clusters with high possibility of clonal relation preferentially form electrical, but not chemical, synapses.
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Affiliation(s)
- Xin-Jun Zhang
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Zhizhong Li
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Zhi Han
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,College of Software, Nankai University, Tianjin 300071, China
| | - Khadeejah T Sultan
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA.,Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10065, USA
| | - Kun Huang
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Song-Hai Shi
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA.,Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10065, USA
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20
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Witter MP, Doan TP, Jacobsen B, Nilssen ES, Ohara S. Architecture of the Entorhinal Cortex A Review of Entorhinal Anatomy in Rodents with Some Comparative Notes. Front Syst Neurosci 2017; 11:46. [PMID: 28701931 PMCID: PMC5488372 DOI: 10.3389/fnsys.2017.00046] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/07/2017] [Indexed: 12/18/2022] Open
Abstract
The entorhinal cortex (EC) is the major input and output structure of the hippocampal formation, forming the nodal point in cortico-hippocampal circuits. Different division schemes including two or many more subdivisions have been proposed, but here we will argue that subdividing EC into two components, the lateral EC (LEC) and medial EC (MEC) might suffice to describe the functional architecture of EC. This subdivision then leads to an anatomical interpretation of the different phenotypes of LEC and MEC. First, we will briefly summarize the cytoarchitectonic differences and differences in hippocampal projection patterns on which the subdivision between LEC and MEC traditionally is based and provide a short comparative perspective. Second, we focus on main differences in cortical connectivity, leading to the conclusion that the apparent differences may well correlate with the functional differences. Cortical connectivity of MEC is features interactions with areas such as the presubiculum, parasubiculum, retrosplenial cortex (RSC) and postrhinal cortex, all areas that are considered to belong to the "spatial processing domain" of the cortex. In contrast, LEC is strongly connected with olfactory areas, insular, medial- and orbitofrontal areas and perirhinal cortex. These areas are likely more involved in processing of object information, attention and motivation. Third, we will compare the intrinsic networks involving principal- and inter-neurons in LEC and MEC. Together, these observations suggest that the different phenotypes of both EC subdivisions likely depend on the combination of intrinsic organization and specific sets of inputs. We further suggest a reappraisal of the notion of EC as a layered input-output structure for the hippocampal formation.
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Affiliation(s)
- Menno P. Witter
- Functional Neuroanatomy, KavlI Institute for Systems Neuroscience, Center for Computational Neuroscience, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University of Science and TechnologyTrondheim, Norway
| | - Thanh P. Doan
- Functional Neuroanatomy, KavlI Institute for Systems Neuroscience, Center for Computational Neuroscience, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University of Science and TechnologyTrondheim, Norway
| | - Bente Jacobsen
- Functional Neuroanatomy, KavlI Institute for Systems Neuroscience, Center for Computational Neuroscience, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University of Science and TechnologyTrondheim, Norway
| | - Eirik S. Nilssen
- Functional Neuroanatomy, KavlI Institute for Systems Neuroscience, Center for Computational Neuroscience, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University of Science and TechnologyTrondheim, Norway
| | - Shinya Ohara
- Division of Systems Neuroscience, Tohoku University Graduate School of Life ScienceSendai, Japan
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21
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Dingledine R, Coulter DA, Fritsch B, Gorter JA, Lelutiu N, McNamara J, Nadler JV, Pitkänen A, Rogawski MA, Skene P, Sloviter RS, Wang Y, Wadman WJ, Wasterlain C, Roopra A. Transcriptional profile of hippocampal dentate granule cells in four rat epilepsy models. Sci Data 2017; 4:170061. [PMID: 28485718 PMCID: PMC5423390 DOI: 10.1038/sdata.2017.61] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/04/2017] [Indexed: 12/11/2022] Open
Abstract
Global expression profiling of neurologic or psychiatric disorders has been confounded by variability among laboratories, animal models, tissues sampled, and experimental platforms, with the result being that few genes demonstrate consistent expression changes. We attempted to minimize these confounds by pooling dentate granule cell transcriptional profiles from 164 rats in seven laboratories, using three status epilepticus (SE) epilepsy models (pilocarpine, kainate, self-sustained SE), plus amygdala kindling. In each epilepsy model, RNA was harvested from laser-captured dentate granule cells from six rats at four time points early in the process of developing epilepsy, and data were collected from two independent laboratories in each rodent model except SSSE. Hierarchical clustering of differentially-expressed transcripts in the three SE models revealed complete separation between controls and SE rats isolated 1 day after SE. However, concordance of gene expression changes in the SE models was only 26–38% between laboratories, and 4.5% among models, validating the consortium approach. Transcripts with unusually highly variable control expression across laboratories provide a ‘red herring’ list for low-powered studies.
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Affiliation(s)
- Raymond Dingledine
- Department of Pharmacology, Emory University, Atlanta, Georgia 30322, USA
| | - Douglas A Coulter
- Department of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Brita Fritsch
- Department of Neurology, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Jan A Gorter
- Swammerdam Institute for Life Science, Center for Neuroscience, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands
| | - Nadia Lelutiu
- Department of Pharmacology, Emory University, Atlanta, Georgia 30322, USA
| | - James McNamara
- Department of Neurobiology, Duke University, Durham, North Carolina 27710, USA
| | - J Victor Nadler
- Department of Neurobiology, Duke University, Durham, North Carolina 27710, USA
| | - Asla Pitkänen
- A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, Kuopio FIN-70211, Finland
| | - Michael A Rogawski
- Departments of Neurology and Pharmacology, School of Medicine, University of California, Davis, Sacramento, California 95817, USA
| | - Pate Skene
- Department of Neurobiology, Duke University, Durham, North Carolina 27710, USA
| | - Robert S Sloviter
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia 30310, USA
| | - Yu Wang
- Department of Neurobiology, Duke University, Durham, North Carolina 27710, USA
| | - Wytse J Wadman
- Swammerdam Institute for Life Science, Center for Neuroscience, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands
| | - Claude Wasterlain
- Department of Neurology and Brain Research Institute, and VA Greater Los Angeles Health Care System, Univ. California Los Angeles, Los Angeles, California 90073, USA
| | - Avtar Roopra
- Department of Neuroscience, Univ. Wisconsin, Madison, Wisconsin 53705, USA
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22
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Ivanov AD, Zaitsev AV. NMDAR-independent hippocampal long-term depression impairment after status epilepticus in a lithium-pilocarpine model of temporal lobe epilepsy. Synapse 2017; 71. [PMID: 28432779 DOI: 10.1002/syn.21982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/29/2017] [Accepted: 04/13/2017] [Indexed: 11/07/2022]
Abstract
Temporal lobe epilepsy is usually associated with cognitive decline and memory deficits. Despite numerous existing studies on various animal models, the mechanisms of these deficits remain largely unclear. A specific form of long-term synaptic efficacy changes-long-term depression (LTD)-is thought to play an important role in memory formation and learning. However, extremely little is known about the possible alteration of LTD induction and dynamics after a status epilepticus (SE). In this work, we investigated the acute and delayed effects of lithium-pilocarpine-induced SE on NMDAR-dependent and NMDAR-independent hippocampal LTD in vitro. We found that SE affected the NMDAR-dependent and NMDAR-independent forms of LTD in different manners. The NMDAR-dependent form of LTD was almost intact 3 days after SE, but it switched from a predominantly presynaptic to a more postsynaptic locus of expression. In contrast, the NMDAR-independent LTD in the hippocampal Schaffer collaterals-CA1 synapses was fully abolished 3 days after SE. Our results emphasize the role of non-NMDA-dependent synaptic plasticity changes in the processes of epileptogenesis and the potential for therapy development.
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Affiliation(s)
- Andrey D Ivanov
- Neurophysiology of Learning Laboratory, Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences (IHNA), Moscow, Russia
| | - Aleksey V Zaitsev
- Molecular Mechanisms of Neuronal Interactions Laboratory, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences (IEPhB), Saint Petersburg, Russia.,Institute of Experimental Medicine, Federal Almazov North-West Medical Research Centre, Saint Petersburg, Russia
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23
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Ray S, Burgalossi A, Brecht M, Naumann RK. Complementary Modular Microcircuits of the Rat Medial Entorhinal Cortex. Front Syst Neurosci 2017; 11:20. [PMID: 28443003 PMCID: PMC5385340 DOI: 10.3389/fnsys.2017.00020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/24/2017] [Indexed: 11/13/2022] Open
Abstract
The parahippocampal region is organized into different areas, with the medial entorhinal cortex (MEC), presubiculum and parasubiculum prominent in spatial memory. Here, we also describe a region at the extremity of the MEC and bordering the subicular complex, the medial-most part of the entorhinal cortex. While the subdivisions of hippocampus proper form more or less continuous cell sheets, the superficial layers of the parahippocampal region have a distinct modular architecture. We investigate the spatial distribution, laminar position, and putative connectivity of zinc-positive modules in layer 2 of the MEC of rats and relate them to the calbindin-positive patches previously described in the entorhinal cortex. We found that the zinc-positive modules are complementary to the previously described calbindin-positive patches. We also found that inputs from the presubiculum are directed toward the zinc-positive modules while the calbindin-positive patches received inputs from the parasubiculum. Notably, the dendrites of neurons from layers 3 and 5, positive for Purkinje Cell Protein 4 expression, overlap with the zinc modules. Our data thus indicate that these two complementary modular systems, the calbindin patches and zinc modules, are part of parallel information streams in the hippocampal formation.
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Affiliation(s)
- Saikat Ray
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
| | - Andrea Burgalossi
- Werner-Reichardt Centre for Integrative NeuroscienceTübingen, Germany
| | - Michael Brecht
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
- German Center for Neurodegenerative DiseasesBerlin, Germany
| | - Robert K. Naumann
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
- Max-Planck-Institute for Brain ResearchFrankfurt, Germany
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24
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Alexander A, Maroso M, Soltesz I. Organization and control of epileptic circuits in temporal lobe epilepsy. PROGRESS IN BRAIN RESEARCH 2016; 226:127-54. [PMID: 27323941 PMCID: PMC5140277 DOI: 10.1016/bs.pbr.2016.04.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
When studying the pathological mechanisms of epilepsy, there are a seemingly endless number of approaches from the ultrastructural level-receptor expression by EM-to the behavioral level-comorbid depression in behaving animals. Epilepsy is characterized as a disorder of recurrent seizures, which are defined as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain" (Fisher et al., 2005). Such abnormal activity typically does not occur in a single isolated neuron; rather, it results from pathological activity in large groups-or circuits-of neurons. Here we choose to focus on two aspects of aberrant circuits in temporal lobe epilepsy: their organization and potential mechanisms to control these pathological circuits. We also look at two scales: microcircuits, ie, the relationship between individual neurons or small groups of similar neurons, and macrocircuits, ie, the organization of large-scale brain regions. We begin by summarizing the large body of literature that describes the stereotypical anatomical changes in the temporal lobe-ie, the anatomical basis of alterations in microcircuitry. We then offer a brief introduction to graph theory and describe how this type of mathematical analysis, in combination with computational neuroscience techniques and using parameters obtained from experimental data, can be used to postulate how microcircuit alterations may lead to seizures. We then zoom out and look at the changes which are seen over large whole-brain networks in patients and animal models, and finally we look to the future.
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Affiliation(s)
- A Alexander
- Stanford University, Stanford, CA, United States
| | - M Maroso
- Stanford University, Stanford, CA, United States
| | - I Soltesz
- Stanford University, Stanford, CA, United States.
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