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Puig-Lagunes ÁA, Rocha L, Morgado-Valle C, BeltrÁn-Parrazal L, LÓpez-Meraz ML. Brain and plasma amino acid concentration in infant rats prenatally exposed to valproic acid. AN ACAD BRAS CIENC 2021; 93:e20190861. [PMID: 33729379 DOI: 10.1590/0001-3765202120190861] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 10/19/2019] [Indexed: 11/22/2022] Open
Abstract
Autism spectrum disorder is associated with alterations in GABAergic and glutamatergic neurotransmission. Here, we aimed to determine the concentration of GABA, glutamate, glutamine, aspartate, taurine, and glycine in brain tissue and plasma of rats prenatally exposed to valproic acid (VPA), a well-characterized experimental model of autism. Pregnant rats were injected with VPA (600mg/Kg) during the twelfth-embryonic-day. Control rats were injected with saline. On the fourteen-postnatal-day, rats from both groups (males and females) were anesthetized, euthanized by decapitation and their brain dissected out. The frontal cortex, hippocampus, amygdala, brain stem and cerebellum were dissected and homogenized. Homogenates were centrifuged and supernatants were used to quantify amino acid concentrations by HPLC coupled with fluorometric detection. Blood samples were obtained by a cardiac puncture; plasma was separated and deproteinized to quantify amino acid concentration by HPLC. We found that, in VPA rats, glutamate and glutamine concentrations were increased in hippocampus and glycine concentration was increased in cortex. We did not find changes in other regions or in plasma amino acid concentration in the VPA group with respect to control group. Our results suggest that VPA exposure in utero may impair inhibitory and excitatory amino acid transmission in the infant brain.
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Affiliation(s)
- Ángel Alberto Puig-Lagunes
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Médicos y Odontólogos, s/n, Col. Unidad del Bosque, 91010 Xalapa, Veracruz, México
| | - Luisa Rocha
- Departamento de Farmacobiología, Cinvestav, Calzada de los Tenorios, 235, 14330 Col. Granjas Coapa, Ciudad de México, México
| | - Consuelo Morgado-Valle
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Médicos y Odontólogos, s/n, Col. Unidad del Bosque, 91010 Xalapa, Veracruz, México
| | - Luis BeltrÁn-Parrazal
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Médicos y Odontólogos, s/n, Col. Unidad del Bosque, 91010 Xalapa, Veracruz, México
| | - MarÍa-Leonor LÓpez-Meraz
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Médicos y Odontólogos, s/n, Col. Unidad del Bosque, 91010 Xalapa, Veracruz, México
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Nakamura M, Jang IS, Yamaga T, Kotani N, Akaike N. Effects of nitrous oxide on glycinergic transmission in rat spinal neurons. Brain Res Bull 2020; 162:191-198. [PMID: 32599127 DOI: 10.1016/j.brainresbull.2020.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 11/19/2022]
Abstract
We investigated the effects of nitrous oxide (N2O) on glycinergic inhibitory whole-cell and synaptic responses using a "synapse bouton preparation," dissociated mechanically from rat spinal sacral dorsal commissural nucleus (SDCN) neurons. This technique can evaluate pure single- or multi-synaptic responses from native functional nerve endings and enable us to accurately quantify how N2O influences pre- and postsynaptic transmission. We found that 70 % N2O enhanced exogenous glycine-induced whole-cell currents (IGly) at glycine concentrations lower than 3 × 10-5 M, but did not affect IGly at glycine concentrations higher than 10-4 M. N2O did not affect the amplitude and 1/e decay-time of both spontaneous and miniature glycinergic inhibitory postsynaptic currents recorded in the absence and presence of tetrodotoxin (sIPSCs and mIPSCs, respectively). The decrease in frequency induced by N2O was observed in sIPSCs but not in mIPSCs, which was recorded in the presence of both tetrodotoxin and Cd2+, which block voltage-gated Na+ and Ca2+ channels, respectively. N2O also decreased the amplitude and increased the failure rate and paired-pulse ratio of action potential-evoked glycinergic inhibitory postsynaptic currents. N2O slightly decreased the Ba2+ currents mediated by voltage-gated Ca2+ channels in SDCN neurons. We found that N2O suppresses glycinergic responses at synaptic levels with presynaptic effect having much more predominant role. The difference between glycinergic whole-cell and synaptic responses suggests that extrasynaptic responses seriously modulate whole-cell currents. Our results strongly suggest that these responses may thus in part explain analgesic effects of N2O via marked glutamatergic inhibition by glycinergic responses in the spinal cord.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea
| | - Toshitaka Yamaga
- 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
| | - Norio Akaike
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama 343-0821, 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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Kubota H, Akaike H, Okamitsu N, Jang IS, Nonaka K, Kotani N, Akaike N. Xenon modulates the GABA and glutamate responses at genuine synaptic levels in rat spinal neurons. Brain Res Bull 2020; 157:51-60. [PMID: 31987927 DOI: 10.1016/j.brainresbull.2020.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 01/11/2023]
Abstract
Effects of xenon (Xe) on whole-cell currents induced by glutamate (Glu), its three ionotropic subtypes, and GABA, as well as on the fast synaptic glutamatergic and GABAergic transmissions, were studied in the mechanically dissociated "synapse bouton preparation" of rat spinal sacral dorsal commissural nucleus (SDCN) neurons. This technique evaluates pure single or multi-synapse responses from native functional nerve endings and enables us to quantify how Xe influences pre- and postsynaptic transmissions accurately. Effects of Xe on glutamate (Glu)-, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-, kainate (KA)- and N-methyl-d-aspartate (NMDA)- and GABAA receptor-mediated whole-cell currents were investigated by the conventional whole-cell patch configuration. Excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) were measured as spontaneous (s) and evoked (e) EPSCs and IPSCs. Evoked synaptic currents were elicited by paired-pulse focal electric stimulation. Xe decreased Glu, AMPA, KA, and NMDA receptor-mediated whole-cell currents but did not change GABAA receptor-mediated whole-cell currents. Xe decreased the frequency and amplitude but did not affect the 1/e decay time of the glutamatergic sEPSCs. Xe decreased the frequency without affecting the amplitude and 1/e decay time of GABAergic sIPSCs. Xe decreased the amplitude and increased the failure rate (Rf) and paired-pulse ratio (PPR) without altering the 1/e decay time of both eEPSC and eIPSC, suggesting that Xe acts on the presynaptic side of the synapse. The presynaptic inhibition was greater in eEPSCs than in eIPSCs. We conclude that Xe decreases glutamatergic and GABAergic spontaneous and evoked transmissions at the presynaptic level. The glutamatergic presynaptic responses are the main target of anesthesia-induced neuronal responses. In contrast, GABAergic responses minimally contribute to Xe anesthesia.
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Affiliation(s)
- Hisahiko Kubota
- Department of Pharmacology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Hironari Akaike
- Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto, 862-0973, Japan
| | - Nobuharu Okamitsu
- Department of Electrics and Computer Engineering, Faculty of Engineering, Hiroshima Institute of Technology, 2-1-1 Miyake, Saeki-ku, Hiroshima, 731-5193, Japan
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea
| | - 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
| | - Norio Akaike
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama, 343-0821, 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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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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Feng HJ, Forman SA. Comparison of αβδ and αβγ GABA A receptors: Allosteric modulation and identification of subunit arrangement by site-selective general anesthetics. Pharmacol Res 2017; 133:289-300. [PMID: 29294355 DOI: 10.1016/j.phrs.2017.12.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 12/27/2022]
Abstract
GABAA receptors play a dominant role in mediating inhibition in the mature mammalian brain, and defects of GABAergic neurotransmission contribute to the pathogenesis of a variety of neurological and psychiatric disorders. Two types of GABAergic inhibition have been described: αβγ receptors mediate phasic inhibition in response to transient high-concentrations of synaptic GABA release, and αβδ receptors produce tonic inhibitory currents activated by low-concentration extrasynaptic GABA. Both αβδ and αβγ receptors are important targets for general anesthetics, which induce apparently different changes both in GABA-dependent receptor activation and in desensitization in currents mediated by αβγ vs. αβδ receptors. Many of these differences are explained by correcting for the high agonist efficacy of GABA at most αβγ receptors vs. much lower efficacy at αβδ receptors. The stoichiometry and subunit arrangement of recombinant αβγ receptors are well established as β-α-γ-β-α, while those of αβδ receptors remain controversial. Importantly, some potent general anesthetics selectively bind in transmembrane inter-subunit pockets of αβγ receptors: etomidate acts at β+/α- interfaces, and the barbiturate R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB) acts at α+/β- and γ+/β- interfaces. Thus, these drugs are useful as structural probes in αβδ receptors formed from free subunits or concatenated subunit assemblies designed to constrain subunit arrangement. Although a definite conclusion cannot be drawn, studies using etomidate and R-mTFD-MPAB support the idea that recombinant α1β3δ receptors may share stoichiometry and subunit arrangement with α1β3γ2 receptors.
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Affiliation(s)
- Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
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Wakita M, Kotani N, Akaike N. Effects of propofol on glycinergic neurotransmission in a single spinal nerve synapse preparation. Brain Res 2015; 1631:147-56. [PMID: 26616339 DOI: 10.1016/j.brainres.2015.11.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/13/2015] [Accepted: 11/17/2015] [Indexed: 12/30/2022]
Abstract
The effects of the intravenous anesthetic, propofol, on glycinergic transmission and on glycine receptor-mediated whole-cell currents (IGly) were examined in the substantia gelatinosa (SG) neuronal cell body, mechanically dissociated from the rat spinal cord. This "synaptic bouton" preparation, which retains functional native nerve endings, allowed us to evaluate glycinergic inhibitory postsynaptic currents (IPSCs) and whole-cell currents in a preparation in which experimental solution could rapidly access synaptic terminals. Synaptic IPSCs were measured as spontaneous (s) and evoked (e) IPSCs. The eIPSCs were elicited by applying paired-pulse focal electrical stimulation, while IGly was evoked by a bath application of glycine. A concentration-dependent enhancement of IGly was observed for ≥10µM propofol. Propofol (≥3µM) significantly increased the frequency of sIPSCs and prolonged the decay time without altering the current amplitude. However, propofol (≥3µM) also significantly increased the mean amplitude of eIPSCs and decreased the failure rate (Rf). A decrease in the paired-pulse ratio (PPR) was noted at higher concentrations (≥10µM). The decay time of eIPSCs was prolonged only at the maximum concentration tested (30µM). Propofol thus acts at both presynaptic glycine release machinery and postsynaptic glycine receptors. At clinically relevant concentrations (<1μM) there was no effect on IGly, sIPSCs or eIPSCs suggesting that at anesthetic doses propofol does not affect inhibitory glycinergic synapses in the spinal cord.
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Affiliation(s)
- Masahito Wakita
- Research Division for Clinical Pharmacology, Medical Corporation, JyuryoGroup, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kitaku, Kumamoto 860-8518, Japan; Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan
| | - Naoki Kotani
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya 343-0821, Japan
| | - Norio Akaike
- Research Division for Clinical Pharmacology, Medical Corporation, JyuryoGroup, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kitaku, Kumamoto 860-8518, Japan; Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya 343-0821, Japan; Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
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Wakita M, Kotani N, Yamaga T, Akaike N. Nitrous oxide directly inhibits action potential-dependent neurotransmission from single presynaptic boutons adhering to rat hippocampal CA3 neurons. Brain Res Bull 2015; 118:34-45. [PMID: 26343381 DOI: 10.1016/j.brainresbull.2015.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 11/16/2022]
Abstract
We evaluated the effects of N2O on synaptic transmission using a preparation of mechanically dissociated rat hippocampal CA3 neurons that allowed assays of single bouton responses evoked from native functional nerve endings. We studied the effects of N2O on GABAA, glutamate, AMPA and NMDA receptor-mediated currents (IGABA, IGlu, IAMPA and INMDA) elicited by exogenous application of GABA, glutamate, (S)-AMPA, and NMDA and spontaneous, miniature, and evoked GABAergic inhibitory and glutamatergic excitatory postsynaptic current (sIPSC, mIPSC, eIPSC, sEPSC, mEPSC and eEPSC) in mechanically dissociated CA3 neurons. eIPSC and eEPSC were evoked by focal electrical stimulation of a single bouton. Administration of 70% N2O altered neither IGABA nor the frequency and amplitude of both sIPSCs and mIPSCs. In contrast, N2O decreased the amplitude of eIPSCs, while increasing failure rates (Rf) and paired-pulse ratios (PPR) in a concentration-dependent manner. On the other hand, N2O decreased IGlu, IAMPA and INMDA. Again N2O did not change the frequency and amplitude of either sEPSCs of mEPSCs. N2O also decreased amplitudes of eEPSCs with increased Rf and PPR. The decay phases of all synaptic responses were unchanged. The present results indicated that N2O inhibits the activation of AMPA/KA and NMDA receptors and also that N2O preferentially depress the action potential-dependent GABA and glutamate releases but had little effects on spontaneous and miniature releases.
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Affiliation(s)
- Masahito Wakita
- Research Division for Clinical Pharmacology, Medical Corporation, Jyuryo Group, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kitaku, Kumamoto 860-8518, Japan; Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan
| | - Naoki Kotani
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama 343-0821, Japan
| | - Toshitaka Yamaga
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan
| | - Norio Akaike
- Research Division for Clinical Pharmacology, Medical Corporation, Jyuryo Group, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kitaku, Kumamoto 860-8518, Japan; Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6 Kawarasone, Koshigaya, Saitama 343-0821, Japan.
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Wakita M, Nagami H, Takase Y, Nakanishi R, Kotani N, Akaike N. Modifications of excitatory and inhibitory transmission in rat hippocampal pyramidal neurons by acute lithium treatment. Brain Res Bull 2015; 117:39-44. [PMID: 26247839 DOI: 10.1016/j.brainresbull.2015.07.009] [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: 02/26/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 11/25/2022]
Abstract
The acute effects of high-dose Li(+) treatment on glutamatergic and GABAergic transmissions were studied in the "synaptic bouton" preparation of isolated rat hippocampal pyramidal neurons by using focal electrical stimulation. Both action potential-dependent glutamatergic excitatory and GABAergic inhibitory postsynaptic currents (eEPSC and eIPSC, respectively) were dose-dependently inhibited in the external media containing 30-150 mM Li(+), but the sensitivity for Li(+) was greater tendency for eEPSCs than for eIPSCs. When the effects of Li(+) on glutamate or GABAA receptor-mediated whole-cell responses (IGlu and IGABA) elicited by an exogenous application of glutamate or GABA were examined in the postsynaptic soma membrane of CA3 neurons, Li(+) slightly inhibited both IGlu and IGABA at the 150 mM Li(+) concentration. Present results suggest that acute treatment with high concentrations of Li(+) acts preferentially on presynaptic terminals, and that the Li(+)-induced inhibition may be greater for excitatory than for inhibitory transmission.
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Affiliation(s)
- Masahito Wakita
- Research Division for Clinical Pharmacology, Medical Corporation, Juryokai, Kumamoto Kinoh Hospital, 6-8-1, Yamamuro, Kita-ku, Kumamoto 860-8518, Japan
| | - Hideaki Nagami
- Research Division for Clinical Pharmacology, Medical Corporation, Juryokai, Kumamoto Kinoh Hospital, 6-8-1, Yamamuro, Kita-ku, Kumamoto 860-8518, Japan
| | - Yuko Takase
- Research Division for Clinical Pharmacology, Medical Corporation, Juryokai, Kumamoto Kinoh Hospital, 6-8-1, Yamamuro, Kita-ku, Kumamoto 860-8518, Japan
| | - Ryoji Nakanishi
- Research Division for Clinical Pharmacology, Medical Corporation, Juryokai, Kumamoto Kinoh Hospital, 6-8-1, Yamamuro, Kita-ku, Kumamoto 860-8518, Japan
| | - Naoki Kotani
- Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6, Kawarasone, Koshigaya 343-0821, Japan
| | - Norio Akaike
- Research Division for Clinical Pharmacology, Medical Corporation, Juryokai, Kumamoto Kinoh Hospital, 6-8-1, Yamamuro, Kita-ku, Kumamoto 860-8518, Japan; Research Division of Neurophysiology, Kitamoto Hospital, 3-7-6, Kawarasone, Koshigaya 343-0821, Japan; Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
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Wakita M, Kotani N, Shoudai K, Yamaga T, Akaike N. Modulation of inhibitory and excitatory fast neurotransmission in the rat CNS by heavy water (D2O). J Neurophysiol 2015; 114:1109-18. [PMID: 26019316 DOI: 10.1152/jn.00801.2014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 05/26/2015] [Indexed: 11/22/2022] Open
Abstract
The effects of heavy water (deuterium oxide, D2O) on GABAergic and glutamatergic spontaneous and evoked synaptic transmission were investigated in acute brain slice and isolated "synaptic bouton" preparations of rat hippocampal CA3 neurons. The substitution of D2O for H2O reduced the frequency and amplitude of GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) in a concentration-dependent manner but had no effect on glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs). In contrast, for evoked synaptic responses in isolated neurons, the amplitude of both inhibitory and excitatory postsynaptic currents (eIPSCs and eEPSCs) was decreased in a concentration-dependent manner. This was associated with increases of synaptic failure rate (Rf) and paired-pulse ratio (PPR). The effect was larger for eIPSCs compared with eEPSCs. These results clearly indicate that D2O acts differently on inhibitory and excitatory neurotransmitter release machinery. Furthermore, D2O significantly suppressed GABAA receptor-mediated whole cell current (IGABA) but did not affect glutamate receptor-mediated whole cell current (IGlu). The combined effects of D2O at both the pre- and postsynaptic sites may explain the greater inhibition of eIPSCs compared with eEPSCs. Finally, D2O did not enhance or otherwise affect the actions of the general anesthetics nitrous oxide and propofol on spontaneous or evoked GABAergic and glutamatergic neurotransmissions, or on IGABA and IGlu. Our results suggest that previously reported effects of D2O to mimic and/or modulate anesthesia potency result from mechanisms other than modulation of GABAergic and glutamatergic neurotransmission.
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Affiliation(s)
- Masahito Wakita
- Research Division for Clinical Pharmacology, Medical Corporation, Jyuryo Group, Kumamoto Kinoh Hospital, Kitaku, Kumamoto, Japan; Research Division for Life Science, Kumamoto Health Science University, Kitaku, Kumamoto, Japan; and
| | - Naoki Kotani
- Research Division of Neurophysiology, Kitamoto Hospital, Koshigaya, Japan
| | - Kiyomitsu Shoudai
- Research Division for Life Science, Kumamoto Health Science University, Kitaku, Kumamoto, Japan; and
| | - Toshitaka Yamaga
- Research Division for Life Science, Kumamoto Health Science University, Kitaku, Kumamoto, Japan; and
| | - Norio Akaike
- Research Division for Clinical Pharmacology, Medical Corporation, Jyuryo Group, Kumamoto Kinoh Hospital, Kitaku, Kumamoto, Japan; Research Division for Life Science, Kumamoto Health Science University, Kitaku, Kumamoto, Japan; and Research Division of Neurophysiology, Kitamoto Hospital, Koshigaya, Japan
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Wakita M, Kotani N, Nonaka K, Shin MC, Akaike N. Effects of propofol on GABAergic and glutamatergic transmission in isolated hippocampal single nerve-synapse preparations. Eur J Pharmacol 2013; 718:63-73. [DOI: 10.1016/j.ejphar.2013.09.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 08/26/2013] [Accepted: 09/04/2013] [Indexed: 01/12/2023]
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