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Gaidin SG, Maiorov SA, Laryushkin DP, Zinchenko VP, Kosenkov AM. A novel approach for vital visualization and studying of neurons containing Ca 2+ -permeable AMPA receptors. J Neurochem 2023; 164:583-597. [PMID: 36415923 DOI: 10.1111/jnc.15729] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 10/19/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022]
Abstract
Calcium-permeable AMPA receptors (CP-AMPARs) play a pivotal role in brain functioning in health and disease. They are involved in synaptic plasticity, synaptogenesis, and neuronal circuits development. However, the functions of neurons expressing CP-AMPARs and their role in the modulation of network activity remain elusive since reliable and accurate visualization methods are absent. Here we developed an approach allowing the vital identification of neurons containing CP-AMPARs. The proposed method relies on evaluating Ca2+ influx in neurons during activation of AMPARs in the presence of NMDAR and KAR antagonists, and blockers of voltage-gated Ca2+ channels. Using this method, we studied the properties of CP-AMPARs-containing neurons. We showed that the overwhelming majority of neurons containing CP-AMPARs are GABAergic, and they are distinguished by higher amplitudes of the calcium responses to applications of the agonists. Furthermore, about 30% of CP-AMPARs-containing neurons demonstrate the presence of GluK1-containing KARs. Although CP-AMPARs-containing neurons are characterized by more significant Ca2+ influx during the activation of AMPARs than other neurons, AMPAR-mediated Na+ influx is similar in these two groups. We revealed that neurons containing CP-AMPARs demonstrate weak GABA(A)R-mediated inhibition because of the low percentage of GABAergic synapses on the soma of these cells. However, our data show that weak GABA(A)R-mediated inhibition is inherent to all GABAergic neurons in the culture and cannot be considered a unique feature of CP-AMPARs-containing neurons. We believe that the suggested approach will help to understand the role of CP-AMPARs in the mammalian nervous system in more detail.
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Affiliation(s)
- Sergei G Gaidin
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russia
| | - Sergei A Maiorov
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russia
| | - Denis P Laryushkin
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russia
| | - Valery P Zinchenko
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russia
| | - Artem M Kosenkov
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russia
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Laryushkin DP, Maiorov SA, Zinchenko VP, Gaidin SG, Kosenkov AM. Role of L-Type Voltage-Gated Calcium Channels in Epileptiform Activity of Neurons. Int J Mol Sci 2021; 22:ijms221910342. [PMID: 34638683 PMCID: PMC8508770 DOI: 10.3390/ijms221910342] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/17/2021] [Accepted: 09/23/2021] [Indexed: 12/11/2022] Open
Abstract
Epileptic discharges manifest in individual neurons as abnormal membrane potential fluctuations called paroxysmal depolarization shift (PDS). PDSs can combine into clusters that are accompanied by synchronous oscillations of the intracellular Ca2+ concentration ([Ca2+]i) in neurons. Here, we investigate the contribution of L-type voltage-gated calcium channels (VGCC) to epileptiform activity induced in cultured hippocampal neurons by GABA(A)R antagonist, bicuculline. Using KCl-induced depolarization, we determined the optimal effective doses of the blockers. Dihydropyridines (nifedipine and isradipine) at concentrations ≤ 10 μM demonstrate greater selectivity than the blockers from other groups (phenylalkylamines and benzothiazepines). However, high doses of dihydropyridines evoke an irreversible increase in [Ca2+]i in neurons and astrocytes. In turn, verapamil and diltiazem selectively block L-type VGCC in the range of 1–10 μM, whereas high doses of these drugs block other types of VGCC. We show that L-type VGCC blockade decreases the half-width and amplitude of bicuculline-induced [Ca2+]i oscillations. We also observe a decrease in the number of PDSs in a cluster and cluster duration. However, the pattern of individual PDSs and the frequency of the cluster occurrence change insignificantly. Thus, our results demonstrate that L-type VGCC contributes to maintaining the required [Ca2+]i level during oscillations, which appears to determine the number of PDSs in the cluster.
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Affiliation(s)
- Denis P. Laryushkin
- Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia;
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (S.A.M.); (V.P.Z.)
| | - Sergei A. Maiorov
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (S.A.M.); (V.P.Z.)
| | - Valery P. Zinchenko
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (S.A.M.); (V.P.Z.)
| | - Sergei G. Gaidin
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (S.A.M.); (V.P.Z.)
- Correspondence: (S.G.G.); (A.M.K.)
| | - Artem M. Kosenkov
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (S.A.M.); (V.P.Z.)
- Correspondence: (S.G.G.); (A.M.K.)
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Meyer C, Kettner A, Hochenegg U, Rubi L, Hilber K, Koenig X, Boehm S, Hotka M, Kubista H. On the Origin of Paroxysmal Depolarization Shifts: The Contribution of Ca v1.x Channels as the Common Denominator of a Polymorphous Neuronal Discharge Pattern. Neuroscience 2021; 468:265-281. [PMID: 34015369 DOI: 10.1016/j.neuroscience.2021.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 04/29/2021] [Accepted: 05/08/2021] [Indexed: 11/15/2022]
Abstract
Since their discovery in the 1960s, the term paroxysmal depolarization shift (PDS) has been applied to a wide variety of reinforced neuronal discharge patterns. Occurrence of PDS as cellular correlates of electrographic spikes during latent phases of insult-induced rodent epilepsy models and their resemblance to giant depolarizing potentials (GDPs) nourished the idea that PDS may be involved in epileptogenesis. Both GDPs and - in analogy - PDS may lead to progressive changes of neuronal properties by generation of pulsatile intracellular Ca2+ elevations. Herein, a key element is the gating of L-type voltage gated Ca2+ channels (LTCCs, Cav1.x family), which may convey Ca2+ signals to the nucleus. Accordingly, the present study investigates various insult-associated neuronal challenges for their propensities to trigger PDS in a LTCC-dependent manner. Our data demonstrate that diverse disturbances of neuronal function are variably suited to induce PDS-like events, and the contribution of LTCCs is essential to evoke PDS in rat hippocampal neurons that closely resemble GDPs. These PDS appear to be initiated in the dendritic sub-compartment. Their morphology critically depends on the position of recording electrodes and on their rate of occurrence. These results provide novel insight into induction mechanisms, origin, variability, and co-existence of PDS with other discharge patterns and thereby pave the way for future investigations regarding the role of PDS in epileptogenesis.
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Affiliation(s)
- Christiane Meyer
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Annika Kettner
- University of Applied Sciences (FH Campus Wien), Favoritenstrasse 226, 1100 Vienna, Austria.
| | - Ulla Hochenegg
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Lena Rubi
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Karlheinz Hilber
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Xaver Koenig
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Stefan Boehm
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Matej Hotka
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Helmut Kubista
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
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Ratnadurai-Giridharan S, Stefanescu RA, Khargonekar PP, Carney PR, Talathi SS. Genesis of interictal spikes in the CA1: a computational investigation. Front Neural Circuits 2014; 8:2. [PMID: 24478636 PMCID: PMC3902301 DOI: 10.3389/fncir.2014.00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 01/07/2014] [Indexed: 11/13/2022] Open
Abstract
Interictal spikes (IISs) are spontaneous high amplitude, short time duration <400 ms events often observed in electroencephalographs (EEG) of epileptic patients. In vitro analysis of resected mesial temporal lobe tissue from patients with refractory temporal lobe epilepsy has revealed the presence of IIS in the CA1 subfield. In this paper, we develop a biophysically relevant network model of the CA1 subfield and investigate how changes in the network properties influence the susceptibility of CA1 to exhibit an IIS. We present a novel template based approach to identify conditions under which synchronization of paroxysmal depolarization shift (PDS) events evoked in CA1 pyramidal (Py) cells can trigger an IIS. The results from this analysis are used to identify the synaptic parameters of a minimal network model that is capable of generating PDS in response to afferent synaptic input. The minimal network model parameters are then incorporated into a detailed network model of the CA1 subfield in order to address the following questions: (1) How does the formation of an IIS in the CA1 depend on the degree of sprouting (recurrent connections) between the CA1 Py cells and the fraction of CA3 Shaffer collateral (SC) connections onto the CA1 Py cells? and (2) Is synchronous afferent input from the SC essential for the CA1 to exhibit IIS? Our results suggest that the CA1 subfield with low recurrent connectivity (absence of sprouting), mimicking the topology of a normal brain, has a very low probability of producing an IIS except when a large fraction of CA1 neurons (>80%) receives a barrage of quasi-synchronous afferent input (input occurring within a temporal window of ≤24 ms) via the SC. However, as we increase the recurrent connectivity of the CA1 (Psprout > 40); mimicking sprouting in a pathological CA1 network, the CA1 can exhibit IIS even in the absence of a barrage of quasi-synchronous afferents from the SC (input occurring within temporal window >80 ms) and a low fraction of CA1 Py cells (≈30%) receiving SC input. Furthermore, we find that in the presence of Poisson distributed random input via SC, the CA1 network is able to generate spontaneous periodic IISs (≈3 Hz) for high degrees of recurrent Py connectivity (Psprout > 70). We investigate the conditions necessary for this phenomenon and find that spontaneous IISs closely depend on the degree of the network's intrinsic excitability.
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Affiliation(s)
| | - Roxana A Stefanescu
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan Ann Arbor, MI, USA
| | | | - Paul R Carney
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL, USA ; Department of Pediatrics, University of Florida Gainesville, FL, USA
| | - Sachin S Talathi
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL, USA ; Department of Pediatrics, University of Florida Gainesville, FL, USA ; Qualcomm Corp R&D San Diego, CA, USA
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