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Kotani N, Jang IS, Nakamura M, Nonaka K, Nagami H, Akaike N. Depression of Synaptic N-methyl-D-Aspartate Responses by Xenon and Nitrous Oxide. J Pharmacol Exp Ther 2023; 384:187-196. [PMID: 36272733 DOI: 10.1124/jpet.122.001346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/12/2022] [Accepted: 10/14/2022] [Indexed: 12/13/2022] Open
Abstract
In "synapse bouton preparation" of rat hippocampal CA3 neurons, we examined how Xe and N2O modulate N-methyl-D-aspartate (NMDA) receptor-mediated spontaneous and evoked excitatory post-synaptic currents (sEPSCNMDA and eEPSCNMDA). This preparation is a mechanically isolated single neuron attached with nerve endings (boutons) preserving normal physiologic function and promoting the exact evaluation of sEPSCNMDA and eEPSCNMDA responses without influence of extrasynaptic, glial, and other neuronal tonic currents. These sEPSCs and eEPSCs are elicited by spontaneous glutamate release from many homologous glutamatergic boutons and by focal paired-pulse electric stimulation of a single bouton, respectively. The s/eEPSCAMPA/KA and s/eEPSCNMDA were isolated pharmacologically by their specific antagonists. Thus, independent contributions of pre- and postsynaptic responses could also be quantified. All kinetic properties of s/eEPSCAMPA/KA and s/eEPSCNMDA were detected clearly. The s/eEPSCNMDA showed smaller amplitude and slower rise and 1/e decay time constant (τ Decay) than s/eEPSCAMPA/KA Xe (70%) and N2O (70%) significantly decreased the frequency and amplitude without altering the τ Decay of sEPSCNMDA They also decreased the amplitude but increased the Rf and PPR without altering the τ Decay of the eEPSCNMDA These data show clearly that "synapse bouton preparation" can be an accurate model for evaluating s/eEPSCNMDA Such inhibitory effects of gas anesthetics are primarily due to presynaptic mechanisms. Present results may explain partially the powerful analgesic effects of Xe and N2O. SIGNIFICANCE STATEMENT: We could record pharmacologically isolated NMDA receptor-mediated spontaneous and (action potential-evoked) excitatory postsynaptic currents (sEPSCNMDA and eEPSCNMDA) and clearly detect all kinetic parameters of sEPSCNMDA and eEPSCNMDA at synaptic levels by using "synapse bouton preparation" of rat hippocampal CA3 neurons. We found that Xe and N2O clearly suppressed both sEPSCNMDA and eEPSCNMDA. Different from previous studies, present results suggest that Xe and N2O predominantly inhibit the NMDA responses by presynaptic mechanisms.
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Affiliation(s)
- Naoki Kotani
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
| | - Il-Sung Jang
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
| | - Michiko Nakamura
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
| | - Kiku Nonaka
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
| | - Hideaki Nagami
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
| | - Norio Akaike
- Kitamoto Hospital, Saitama, Japan (N.K., N.A.); Kyungpook National University, Daegu, Republic of Korea (I.S.J., M.N.); Kumamoto Health Science University, Kumamoto, Japan (K.N.), and Kumamoto Kinoh Hospital, Kumamoto, Japan (H.N., N.A.)
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Nonaka K, Kotani N, Akaike H, Shin MC, Yamaga T, Nagami H, Akaike N. Xenon modulates synaptic transmission to rat hippocampal CA3 neurons at both pre- and postsynaptic sites. J Physiol 2019; 597:5915-5933. [PMID: 31598974 DOI: 10.1113/jp278762] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 10/07/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Xenon (Xe) non-competitively inhibited whole-cell excitatory glutamatergic current (IGlu ) and whole-cell currents gated by ionotropic glutamate receptors (IAMPA , IKA , INMDA ), but had no effect on inhibitory GABAergic whole-cell current (IGABA ). Xe decreased only the frequency of glutamatergic spontaneous and miniature excitatory postsynaptic currents and GABAergic spontaneous inhibitory postsynaptic currents without changing the amplitude or decay times of these synaptic responses. Xe decreased the amplitude of both the action potential-evoked excitatory and the action potential-evoked inhibitory postsynaptic currents (eEPSCs and eIPSCs, respectively) via a presynaptic inhibition in transmitter release. We conclude that the main site of action of Xe is presynaptic in both excitatory and inhibitory synapses, and that the Xe inhibition is much greater for eEPSCs than for eIPSCs. ABSTRACT To clarify how xenon (Xe) modulates excitatory and inhibitory whole-cell and synaptic responses, we conducted an electrophysiological experiment using the 'synapse bouton preparation' dissociated mechanically from the rat hippocampal CA3 region. This technique can evaluate pure single- or multi-synapse responses and enabled us to accurately quantify how Xe influences pre- and postsynaptic aspects of synaptic transmission. Xe inhibited whole-cell glutamatergic current (IGlu ) and whole-cell currents gated by the three subtypes of glutamate receptor (IAMPA , IKA and INMDA ). Inhibition of these ionotropic currents occurred in a concentration-dependent, non-competitive and voltage-independent manner. Xe markedly depressed the slow steady current component of IAMPA almost without altering the fast phasic IAMPA component non-desensitized by cyclothiazide. It decreased current frequency without affecting the amplitude and current kinetics of glutamatergic spontaneous excitatory postsynaptic currents and miniature excitatory postsynaptic currents. It decreased the amplitude, increasing the failure rate (Rf) and paired-pulse rate (PPR) without altering the current kinetics of glutamatergic action potential-evoked excitatory postsynaptic currents. Thus, Xe has a clear presynaptic effect on excitatory synaptic transmission. Xe did not alter the GABA-induced whole-cell current (IGABA ). It decreased the frequency of GABAergic spontaneous inhibitory postsynaptic currents without changing the amplitude and current kinetics. It decreased the amplitude and increased the PPR and Rf of the GABAergic action potential-evoked inhibitory postsynaptic currents without altering the current kinetics. Thus, Xe acts exclusively at presynaptic sites at the GABAergic synapse. In conclusion, our data indicate that a presynaptic decrease of excitatory transmission is likely to be the major mechanism by which Xe induces anaesthesia, with little contribution of effects on GABAergic synapses.
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Affiliation(s)
- Kiku Nonaka
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kita-ku, Kumamoto, 861-5598, Japan
| | - Naoki Kotani
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama, 343-0821, Japan
| | - Hironari Akaike
- Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto, 862-0973, Japan
| | - Min-Chul Shin
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kita-ku, Kumamoto, 861-5598, Japan
| | - Toshitaka Yamaga
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kita-ku, Kumamoto, 861-5598, Japan
| | - Hideaki Nagami
- Research Division for Clinical Pharmacology, Medical Corporation, Juryo Group, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kita-ku, Kumamoto, 860-8518, Japan
| | - Norio Akaike
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama, 343-0821, Japan.,Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto, 862-0973, Japan.,Research Division for Clinical Pharmacology, Medical Corporation, Juryo Group, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kita-ku, Kumamoto, 860-8518, Japan
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Chelini G, Pantazopoulos H, Durning P, Berretta S. The tetrapartite synapse: a key concept in the pathophysiology of schizophrenia. Eur Psychiatry 2018; 50:60-69. [PMID: 29503098 PMCID: PMC5963512 DOI: 10.1016/j.eurpsy.2018.02.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 02/01/2018] [Accepted: 02/13/2018] [Indexed: 12/20/2022] Open
Abstract
Growing evidence points to synaptic pathology as a core component of the pathophysiology of schizophrenia (SZ). Significant reductions of dendritic spine density and altered expression of their structural and molecular components have been reported in several brain regions, suggesting a deficit of synaptic plasticity. Regulation of synaptic plasticity is a complex process, one that requires not only interactions between pre- and post-synaptic terminals, but also glial cells and the extracellular matrix (ECM). Together, these elements are referred to as the ‘tetrapartite synapse’, an emerging concept supported by accumulating evidence for a role of glial cells and the extracellular matrix in regulating structural and functional aspects of synaptic plasticity. In particular, chondroitin sulfate proteoglycans (CSPGs), one of the main components of the ECM, have been shown to be synthesized predominantly by glial cells, to form organized perisynaptic aggregates known as perineuronal nets (PNNs), and to modulate synaptic signaling and plasticity during postnatal development and adulthood. Notably, recent findings from our group and others have shown marked CSPG abnormalities in several brain regions of people with SZ. These abnormalities were found to affect specialized ECM structures, including PNNs, as well as glial cells expressing the corresponding CSPGs. The purpose of this review is to bring forth the hypothesis that synaptic pathology in SZ arises from a disruption of the interactions between elements of the tetrapartite synapse.
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Affiliation(s)
- Gabriele Chelini
- Translational Neuroscience Laboratory, Mclean Hospital, 115 Mill Street, Belmont, MA, 02478 USA; Dept. of Psychiatry, Harvard Medical School, 25 Shattuck St, Boston, MA, 02115 USA.
| | - Harry Pantazopoulos
- Translational Neuroscience Laboratory, Mclean Hospital, 115 Mill Street, Belmont, MA, 02478 USA; Dept. of Psychiatry, Harvard Medical School, 25 Shattuck St, Boston, MA, 02115 USA.
| | - Peter Durning
- Translational Neuroscience Laboratory, Mclean Hospital, 115 Mill Street, Belmont, MA, 02478 USA.
| | - Sabina Berretta
- Translational Neuroscience Laboratory, Mclean Hospital, 115 Mill Street, Belmont, MA, 02478 USA; Dept. of Psychiatry, Harvard Medical School, 25 Shattuck St, Boston, MA, 02115 USA; Program in Neuroscience, Harvard Medical School, 220 Longwood Ave., Boston, MA, 02115 USA.
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