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Isoflurane CA1 synaptic

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https://www.readbyqxmd.com/read/24977633/anesthetic-agent-specific-effects-on-synaptic-inhibition
#1
M Bruce MacIver
BACKGROUND: Anesthetics enhance ő≥-aminobutyric acid (GABA)-mediated inhibition in the central nervous system. Different agents have been shown to act on tonic versus synaptic GABA receptors to different degrees, but it remains unknown whether different forms of synaptic inhibition are also differentially engaged. With this in mind, we tested the hypothesis that different types of GABA-mediated synapses exhibit different anesthetic sensitivities. The present study compared effects produced by isoflurane, halothane, pentobarbital, thiopental, and propofol on paired-pulse GABAA receptor-mediated synaptic inhibition...
September 2014: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/24758773/isoflurane-impairs-learning-and-hippocampal-long-term-potentiation-via-the-saturation-of-synaptic-plasticity
#2
Kazuhiro Uchimoto, Tomoyuki Miyazaki, Yoshinori Kamiya, Takahiro Mihara, Yukihide Koyama, Masataka Taguri, Gaku Inagawa, Takuya Takahashi, Takahisa Goto
BACKGROUND: General anesthesia induces long-lasting cognitive and learning deficits. However, the underlying mechanism remains unknown. The GluA1 subunit of AMPAR is a key molecule for learning and synaptic plasticity, which requires trafficking of GluA1-containing AMPARs into the synapse. METHODS: Adult male rats were exposed to 1.8% isoflurane for 2 h and subjected to an inhibitory avoidance task, which is a hippocampus-dependent contextual fear learning paradigm (n = 16 to 39)...
August 2014: Anesthesiology
https://www.readbyqxmd.com/read/22705347/fetal-exposure-to-high-isoflurane-concentration-induces-postnatal-memory-and-learning-deficits-in-rats
#3
Fei-Juan Kong, Lei-Lei Ma, Wen-Wen Hu, Wen-Na Wang, Hui-Shun Lu, Shu-Ping Chen
We developed a maternal fetal rat model to study the effects of isoflurane-induced neurotoxicity on the fetuses of pregnant rats exposed in utero. Pregnant rats at gestational day 14 were exposed to 1.3 or 3% isoflurane for 1h. At postnatal day 28, spatial learning and memory of the offspring were examined using the Morris Water Maze. The apoptosis was evaluated by caspase-3 immunohistochemistry in the hippocampal CA1 region. Simultaneously, the ultrastructure changes of synapse in the hippocampal CA1 and dentate gyrus region were observed by transmission electron microscopy (TEM)...
August 15, 2012: Biochemical Pharmacology
https://www.readbyqxmd.com/read/21111749/volatile-anesthetic-effects-on-isolated-gaba-synapses-and-extrasynaptic-receptors
#4
S K Ogawa, E Tanaka, M C Shin, N Kotani, N Akaike
The volatile anesthetics enhance GABAergic inhibitory transmission at synaptic and extrasynaptic sites at central neurons. In the present study, we investigated the effects of three volatile anesthetics (isoflurane, enflurane and sevoflurane) on synaptic and extrasynaptic GABA(A) receptor responses using mechanically dissociated rat hippocampal CA1 neurons in which functional native nerve endings (boutons) were retained. The extrasynaptic GABA(A) receptors were activated by exogenous GABA application while synaptic ones were assessed by miniature and evoked inhibitory postsynaptic currents (mIPSCs and eIPSCs, respectively)...
March 2011: Neuropharmacology
https://www.readbyqxmd.com/read/20435940/presynaptic-actions-of-general-anesthetics-are-responsible-for-frequency-dependent-modification-of-synaptic-transmission-in-the-rat-hippocampal-ca1
#5
Koki Hirota, Rika Sasaki, Sheldon H Roth, Mitsuaki Yamazaki
BACKGROUND: In clinical anesthesia, robust surgical stress occasionally causes unintended light anesthesia during operation. To test the hypothesis that neural input condition could modify actions of general anesthetics as a result of presynaptic alteration in the central nervous system, we investigated the mechanisms by which the stimulus frequency modifies synaptic transmission of the rat hippocampus in the presence of general anesthetics. METHODS: Field population spikes (PSs) of CA1 pyramidal neurons were elicited using orthodromic stimulation of Schaffer collateral-commissural fibers (test-pulse)...
June 1, 2010: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/20058601/-role-of-central-neuronal-nicotinic-receptor-in-the-inhibitory-effect-of-isoflurane-on-synaptic-long-term-potentiation-in-hippocampal-slices-of-rats
#6
Chun-Sheng Feng, Yun Wang, Hai-Chun Ma, Yun Yue
OBJECTIVE: To determine effect of central neuronal nicotinic receptor on synaptic long-term potentiation (LTP) in the CA1 area of rats hippocampal slices. METHODS: Brain slice preparation transverse hippocampal slices were obtained from male Sprague-Dawley rats that were ether-anesthetized and decapitated. The hippocampus was rapidly removed, and slices were prepared in ice-cold artificial cerebrospinal fluid (ACSF), oxygenated with 95% O2 - 5% CO2. Seventy-seven slices were randomly divided into 11 equal groups (n = 7 each): group LTP; group isoflurane 0...
August 18, 2009: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/19765574/isoflurane-and-sevoflurane-dose-dependently-impair-hippocampal-long-term-potentiation
#7
COMPARATIVE STUDY
Rainer Haseneder, Stephan Kratzer, Ludwig von Meyer, Matthias Eder, Eberhard Kochs, Gerhard Rammes
Isoflurane and sevoflurane are commonly used volatile anaesthetics. Although acting via similar cellular mechanisms, the effect of different volatile anaesthetics on synaptic plasticity might differ. In the present study, using acute murine brain slice preparations, we compared the effects of isoflurane and sevoflurane on synaptic transmission and synaptic plasticity (long-term potentiation, LTP) in the CA1 stratum radiatum of the hippocampus. Isoflurane and sevoflurane dose-dependently diminished excitatory postsynaptic field potentials...
November 25, 2009: European Journal of Pharmacology
https://www.readbyqxmd.com/read/19151276/anesthetics-discriminate-between-tonic-and-phasic-gamma-aminobutyric-acid-receptors-on-hippocampal-ca1-neurons
#8
Mark C Bieda, Henry Su, M Bruce Maciver
BACKGROUND: Anesthesia is produced by a depression of neuronal signaling in the central nervous system (CNS); however, the mechanism(s) of action underlying this depression remain unclear. Recent studies have indicated that anesthetics can enhance inhibition of CNS neurons by increasing current flow through tonic gamma-aminobutyric acid (GABA(A)) receptor gated chloride channels in their membranes. Enhanced tonic inhibition would contribute to CNS depression produced by anesthetics, but it remains to be determined to what extent anesthetic actions at these receptors contribute to CNS depression...
February 2009: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/17898380/isoflurane-bidirectionally-modulates-the-paired-pulse-responses-in-the-rat-hippocampal-ca1-field-in-vivo
#9
Kaori Tachibana, Koichi Takita, Toshikazu Hashimoto, Machiko Matsumoto, Mitsuhiro Yoshioka, Yuji Morimoto
BACKGROUND: We studied the effects of isoflurane on hippocampal synaptic transmission and paired-pulse plasticity, under in vivo intact interneuron circuitry. METHODS: Using rats chronically implanted with electrodes, excitatory postsynaptic potential (EPSP) and population spike amplitude (PSA) were measured in the hippocampal CA1 field by stimulating Schaffer collaterals. The lungs of the rats were mechanically ventilated with 0.25-1.5 minimum alveolar anesthetic concentration (MAC) isoflurane...
October 2007: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/17197852/effect-of-isoflurane-and-other-potent-inhaled-anesthetics-on-minimum-alveolar-concentration-learning-and-the-righting-reflex-in-mice-engineered-to-express-alpha1-gamma-aminobutyric-acid-type-a-receptors-unresponsive-to-isoflurane
#10
James M Sonner, David F Werner, Frank P Elsen, Yilei Xing, Mark Liao, R Adron Harris, Neil L Harrison, Michael S Fanselow, Edmond I Eger, Gregg E Homanics
BACKGROUND: Enhancement of the function of gamma-aminobutyric acid type A receptors containing the alpha1 subunit may underlie a portion of inhaled anesthetic action. To test this, the authors created gene knock-in mice harboring mutations that render the receptors insensitive to isoflurane while preserving sensitivity to halothane. METHODS: The authors recorded miniature inhibitory synaptic currents in hippocampal neurons from hippocampal slices from knock-in and wild-type mice...
January 2007: Anesthesiology
https://www.readbyqxmd.com/read/16492827/intravenous-anesthetics-are-more-effective-than-volatile-anesthetics-on-inhibitory-pathways-in-rat-hippocampal-ca1
#11
COMPARATIVE STUDY
Takehisa Asahi, Koki Hirota, Rika Sasaki, Yamazaki Mitsuaki, Sheldon H Roth
In this study, we have examined the effects of both volatile and IV general anesthetics on excitatory synaptic transmission, with and without recurrent inhibition, to clarify whether excitatory or inhibitory synapses are the major targets of action. Field population spike amplitudes (fPSs) of CA1 pyramidal neurons were recorded in rat hippocampal slices. Schaffer-collateral-commissural fibers (Sch) were stimulated orthodromically, and the evoked fPSs (PS[Sch]) in CA1 area were measured. In addition, the fPSs (PS[Alv+Sch]) elicited by stimulation of the Sch after antidromic stimulation of the alveus hippocampi (Alv) to produce recurrent inhibition were determined...
March 2006: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/16409641/isoflurane-depresses-hippocampal-ca1-glutamate-nerve-terminals-without-inhibiting-fiber-volleys
#12
Bruce D Winegar, M Bruce MacIver
BACKGROUND: Anesthetic-induced CNS depression is thought to involve reduction of glutamate release from nerve terminals. Recent studies suggest that isoflurane reduces glutamate release by block of Na channels. To further investigate this question we examined the actions of isoflurane, TTX, extracellular Ca2+, CNQX and stimulus voltage (stim) on glutamate-mediated transmission at hippocampal excitatory synapses. EPSPs were recorded from CA1 neurons in rat hippocampal brain slices in response to Schaffer-collateral fiber stimulation...
2006: BMC Neuroscience
https://www.readbyqxmd.com/read/15579203/multiple-synaptic-and-membrane-sites-of-anesthetic-action-in-the-ca1-region-of-rat-hippocampal-slices
#13
Sky Pittson, Allison M Himmel, M Bruce MacIver
BACKGROUND: Anesthesia is produced by a depression of central nervous system function, however, the sites and mechanisms of action underlying this depression remain poorly defined. The present study compared and contrasted effects produced by five general anesthetics on synaptic circuitry in the CA1 region of hippocampal slices. RESULTS: At clinically relevant and equi-effective concentrations, presynaptic and postsynaptic anesthetic actions were evident at glutamate-mediated excitatory synapses and at GABA-mediated inhibitory synapses...
December 3, 2004: BMC Neuroscience
https://www.readbyqxmd.com/read/15220773/effects-on-synaptic-inhibition-in-the-hippocampus-do-not-underlie-the-amnestic-and-convulsive-properties-of-the-nonimmobilizer-1-2-dichlorohexafluorocyclobutane
#14
Misha Perouansky, Robert A Pearce
BACKGROUND: Although it does not suppress movement in response to noxious stimuli, the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also known as 2N) does cause amnesia and seizures. These occur at 0.48 and 1.3 times, respectively, the concentrations that are predicted from its lipid solubility to cause immobility. The molecular and cellular basis of these effects is not known. The ionotropic gamma-aminobutyric acid type A (GABAA) receptor is modulated strongly by anesthetics, and it plays an important role in many seizure models...
July 2004: Anesthesiology
https://www.readbyqxmd.com/read/11465598/isoflurane-blocks-synaptic-plasticity-in-the-mouse-hippocampus
#15
W Simon, G Hapfelmeier, E Kochs, W Zieglgänsberger, G Rammes
BACKGROUND: The volatile anesthetic isoflurane depresses glutamatergic transmission. In this study, the authors investigated the effects of isoflurane on the induction of long-term potentiation (LTP) and long-term depression (LTD) in slices from the juvenile and adult mouse hippocampus. Both forms of synaptic plasticity involve the activation of glutamate receptors. METHODS: Field excitatory postsynaptic potentials and excitatory postsynaptic currents from neurons in the CA1 area were evoked by stimulation of the Schaffer collateral-commissural pathway...
June 2001: Anesthesiology
https://www.readbyqxmd.com/read/11176100/agent-selective-effects-of-volatile-anesthetics-on-gabaa-receptor-mediated-synaptic-inhibition-in-hippocampal-interneurons
#16
K Nishikawa, M B MacIver
BACKGROUND: A relatively small number of inhibitory interneurons can control the excitability and synchronization of large numbers of pyramidal cells in hippocampus and other cortical regions. Thus, anesthetic modulation of interneurons could play an important role for the maintenance of anesthesia. The aim of this study was to compare effects produced by volatile anesthetics on inhibitory postsynaptic currents (IPSCs) of rat hippocampal interneurons. METHODS: Pharmacologically isolated gamma-aminobutyric acid type A (GABAA) receptor-mediated IPSCs were recorded with whole cell patch-clamp techniques in visually identified interneurons of rat hippocampal slices...
February 2001: Anesthesiology
https://www.readbyqxmd.com/read/11094014/the-involvement-of-adenosine-neuromodulation-in-pentobarbital-induced-field-excitatory-postsynaptic-potentials-depression-in-rat-hippocampal-slices
#17
Y Tohdoh, E Narimatsu, M Kawamata, A Namiki
We investigated the contribution of adenosine neuromodulation to mechanisms of pentobarbital-induced depression of excitatory synaptic transmission in vitro. Transverse hippocampal slices were prepared from brains removed from isoflurane-anesthetized male Wistar rats. Field excitatory postsynaptic potentials (fEPSPs), elicited by orthodromic electrical stimulation of Schaffer collateral at 0.05 Hz, were recorded from the CA1 region in oxygenated artificial cerebrospinal fluid. Amplitude of fEPSP was analyzed for assessing drug effects...
December 2000: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/10638920/excitatory-synaptic-transmission-mediated-by-nmda-receptors-is-more-sensitive-to-isoflurane-than-are-non-nmda-receptor-mediated-responses
#18
COMPARATIVE STUDY
K Nishikawa, M B MacIver
BACKGROUND: Effects of volatile anesthetic agents on N-methyl-D-aspartate (NMDA) receptor-mediated excitatory synaptic transmission have not been well characterized. The authors compared effects produced by halothane and isoflurane on electrophysiologic properties of NMDA and non-NMDA receptor-mediated synaptic responses in slices from the rat hippocampus. METHODS: Field excitatory postsynaptic potentials (fEPSPs) in the CA1 area were recorded with extracellular electrodes after electrical stimulation of Schaffer-collateral-commissural fiber inputs...
January 2000: Anesthesiology
https://www.readbyqxmd.com/read/10072027/the-effects-of-general-anesthetics-on-excitatory-and-inhibitory-synaptic-transmission-in-area-ca1-of-the-rat-hippocampus-in-vitro
#19
M Wakasugi, K Hirota, S H Roth, Y Ito
UNLABELLED: It is unclear whether general anesthetics induce enhancement of neural inhibition and/or attenuation of neural excitation. We studied the effects of pentobarbital (5 x 10(-4) mol/L), propofol (5 x 10(-4) mol/L), ketamine (10(-3) mol/L), halothane (1.5 vol%), and isoflurane (2.0 vol%) on both excitatory and inhibitory synaptic transmission in rat hippocampal slices. Excitatory or inhibitory synaptic pathways were isolated using pharmacological antagonists. Extracellular microelectrodes were used to record electrically evoked CA1 neural population spikes (PSs)...
March 1999: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/10049143/gabaergic-mechanisms-in-the-action-of-general-anesthetics
#20
K Hirota, S H Roth, J Fujimura, A Masuda, Y Ito
1. The effects of volatile and intravenous anesthetics were studied on evoked field potentials in rat hippocampal CA1 neurons in vitro to determine the role of GABAergic mechanisms in the action of general anesthetics. 2. It was observed that both volatile (halothane, isoflurane, sevoflurane) and intravenous (thiopental, pentobarbital, propofol) anesthetics decreased population spike (PS) amplitudes. 3. Using paired-pulse paradigms, it was revealed that volatile agents enhance paired-pulse facilitation (PPF), and intravenous agents reduce PPF...
November 23, 1998: Toxicology Letters
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