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Wang Z, Dong J, Zhang M, Wang S, Wu J, Wang S, Luo Y, Wang Y, Yin Y. Sevoflurane-induced overexpression of extrasynaptic α5-GABA AR via the RhoA/ROCK2 pathway impairs cognitive function in aged mice. Aging Cell 2024:e14209. [PMID: 38825816 DOI: 10.1111/acel.14209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/24/2024] [Accepted: 05/08/2024] [Indexed: 06/04/2024] Open
Abstract
Perioperative neurocognitive disorder (PND) is a serious neurologic complication in aged patients and might be associated with sevoflurane exposure. However, the specific pathogenesis is still unclear. The distribution of α5-GABAAR, a γ-aminobutyric acid type A receptor (GABAAR) subtype, at extrasynaptic sites is influenced by the anchor protein radixin, whose phosphorylation is regulated via the RhoA/ROCK2 signaling pathway and plays a crucial role in cognition. However, whether sevoflurane affects the ability of radixin phosphorylation to alter extrasynaptic receptor expression is unknown. Aged mice were exposed to sevoflurane to induce cognitive impairment. Both total proteins and membrane proteins were extracted for analysis. Cognitive function was evaluated using the Morris water maze and fear conditioning test. Western blotting was used to determine the expression of ROCK2 and the phosphorylation of radixin. Furthermore, the colocalization of p-radixin and α5-GABAAR was observed. To inhibit ROCK2 activity, either an adeno-associated virus (AAV) or fasudil hydrochloride was administered. Aged mice treated with sevoflurane exhibited significant cognitive impairment accompanied by increased membrane expression of α5-GABAAR. Moreover, the colocalization of α5-GABAAR and p-radixin increased after treatment with sevoflurane, and this change was accompanied by an increase in ROCK2 expression and radixin phosphorylation. Notably, inhibiting the RhoA/ROCK2 pathway significantly decreased the distribution of extrasynaptic α5-GABAAR and improved cognitive function. Sevoflurane activates the RhoA/ROCK2 pathway and increases the phosphorylation of radixin. Excess α5-GABAAR is anchored to extrasynaptic sites and impairs cognitive ability in aged mice. Fasudil hydrochloride administration improves cognitive function.
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Affiliation(s)
- Zhun Wang
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Jinpeng Dong
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Mengxue Zhang
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Sixuan Wang
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Jiangnan Wu
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Shengran Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, China
| | - Yuan Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, China
| | - Yiqing Yin
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
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2
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Won D, Lee EH, Chang JE, Nam MH, Park KD, Oh SJ, Hwang JY. The role of astrocytic γ-aminobutyric acid in the action of inhalational anesthetics. Eur J Pharmacol 2024; 970:176494. [PMID: 38484926 DOI: 10.1016/j.ejphar.2024.176494] [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: 12/04/2023] [Revised: 01/24/2024] [Accepted: 03/11/2024] [Indexed: 03/21/2024]
Abstract
BACKGROUND Inhalational anesthetics target the inhibitory extrasynaptic γ-aminobutyric acid type A (GABAA) receptors. Both neuronal and glial GABA mediate tonic inhibition of the extrasynaptic GABAA receptors. However, the role of glial GABA during inhalational anesthesia remains unclear. This study aimed to evaluate whether astrocytic GABA contributes to the action of different inhalational anesthetics. METHODS Gene knockout of monoamine oxidase B (MAOB) was used to reduce astrocytic GABA levels in mice. The hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane were assessed by evaluating the loss of righting reflex (LORR) and tail-pinch withdrawal response (LTWR) in MAOB knockout and wild-type mice. Minimum alveolar concentration (MAC) for LORR, time to LORR, MAC for LTWR and time to LTWR of isoflurane, sevoflurane, and desflurane were assessed. RESULTS Time to LORR and time to LTWR with isoflurane were significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001 and P = 0.032, respectively). Time to LORR with 0.8 MAC of sevoflurane was significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001), but not with 1.0 MAC of sevoflurane (P=0.217). MAC for LTWR was significantly higher in MAOB knockout mice exposed to sevoflurane (P < 0.001). With desflurane, MAOB knockout mice had a significantly higher MAC for LORR (P = 0.003) and higher MAC for LTWR (P < 0.001) than wild-type mice. CONCLUSIONS MAOB knockout mice showed reduced sensitivity to the hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane. Behavioral tests revealed that the hypnotic and immobilizing effects of inhalational anesthetics would be mediated by astrocytic GABA.
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Affiliation(s)
- Dongwook Won
- Department of Anesthesiology and Pain Medicine, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea; College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Elliot H Lee
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Jee-Eun Chang
- Department of Anesthesiology and Pain Medicine, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea; College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Min-Ho Nam
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Ki Duk Park
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Soo-Jin Oh
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea.
| | - Jin-Young Hwang
- Department of Anesthesiology and Pain Medicine, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea; College of Medicine, Seoul National University, Seoul, Republic of Korea.
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3
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Andhika Rhaditya PA, Oishi K, Nishimura YV, Motoyama J. [Ca 2+] i fluctuation mediated by T-type Ca 2+ channel is required for the differentiation of cortical neural progenitor cells. Dev Biol 2022; 489:84-97. [PMID: 35690104 DOI: 10.1016/j.ydbio.2022.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/27/2022] [Accepted: 05/28/2022] [Indexed: 11/17/2022]
Abstract
The fluctuation of intracellular calcium concentration ([Ca2+]i) is known to be involved in various processes in the development of central nervous system, such as the proliferation of neural progenitor cells (NPCs), migration of intermediate progenitor cells (IPCs) from the ventricular zone (VZ) to the subventricular zone (SVZ), and migration of immature neurons from the SVZ to cortical plate. However, the roles of [Ca2+]i fluctuation in NPC development, especially in the differentiation of the self-renewing NPCs into neuron-generating NPCs and immature neurons have not been elucidated. Using calcium imaging of acute cortical slices and cells isolated from mouse embryonic cortex, we examined temporal changes in the pattern of [Ca2+]i fluctuations in VZ cells from E12 to E16. We observed intracellular Ca2+ levels in Pax6-positive self-renewing NPCs decreased with their neural differentiation. In E11, Pax6-positive NPCs and Tuj1-positive immature neurons exhibited characteristic [Ca2+]i fluctuations; few Pax6-positive NPCs exhibited [Ca2+]i transient, but many Tuj1-positive immature neurons did, suggesting that the change in pattern of [Ca2+]i fluctuation correlate to their differentiation. The [Ca2+]i fluctuation during NPCs development was mostly mediated by the T-type calcium channel and blockage of T-type calcium channel in neurosphere cultures increased the number of spheres and inhibited neuronal differentiation. Consistent with this finding, knockdown of Cav3.1 by RNAi in vivo maintained Pax6-positive cells as self-renewing NPCs, and simultaneously suppressing their neuronal differentiation of NPCs into Tbr1-positive immature neurons. These results reveal that [Ca2+]i fluctuation mediated by Cav3.1 is required for the neural differentiation of Pax6-positive self-renewing NPCs.
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Affiliation(s)
- Putu Adi Andhika Rhaditya
- Laboratory of Developmental Neurobiology, Graduate School of Brain Science, Doshisha University, 1-3, Tatara-miyakodani, Kyotanabe, Kyoto, 610-0394, Japan
| | - Koji Oishi
- Organization of Advanced Research and Education, Doshisha University, 1-3, Tatara-miyakodani, Kyotanabe, Kyoto, 610-0394, Japan
| | - Yoshiaki V Nishimura
- Organization of Advanced Research and Education, Doshisha University, 1-3, Tatara-miyakodani, Kyotanabe, Kyoto, 610-0394, Japan; Division of Neuroscience, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai, Miyagi, 983-8536, Japan
| | - Jun Motoyama
- Laboratory of Developmental Neurobiology, Graduate School of Brain Science, Doshisha University, 1-3, Tatara-miyakodani, Kyotanabe, Kyoto, 610-0394, Japan.
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Thalamic T-Type Calcium Channels as Targets for Hypnotics and General Anesthetics. Int J Mol Sci 2022; 23:ijms23042349. [PMID: 35216466 PMCID: PMC8876360 DOI: 10.3390/ijms23042349] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/19/2022] Open
Abstract
General anesthetics mainly act by modulating synaptic inhibition on the one hand (the potentiation of GABA transmission) or synaptic excitation on the other (the inhibition of NMDA receptors), but they can also have effects on numerous other proteins, receptors, and channels. The effects of general anesthetics on ion channels have been the subject of research since the publication of reports of direct actions of these drugs on ion channel proteins. In particular, there is considerable interest in T-type voltage-gated calcium channels that are abundantly expressed in the thalamus, where they control patterns of cellular excitability and thalamocortical oscillations during awake and sleep states. Here, we summarized and discussed our recent studies focused on the CaV3.1 isoform of T-channels in the nonspecific thalamus (intralaminar and midline nuclei), which acts as a key hub through which natural sleep and general anesthesia are initiated. We used mouse genetics and in vivo and ex vivo electrophysiology to study the role of thalamic T-channels in hypnosis induced by a standard general anesthetic, isoflurane, as well as novel neuroactive steroids. From the results of this study, we conclude that CaV3.1 channels contribute to thalamocortical oscillations during anesthetic-induced hypnosis, particularly the slow-frequency range of δ oscillations (0.5–4 Hz), by generating “window current” that contributes to the resting membrane potential. We posit that the role of the thalamic CaV3.1 isoform of T-channels in the effects of various classes of general anesthetics warrants consideration.
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5
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Coulter I, Timic Stamenic T, Eggan P, Fine BR, Corrigan T, Covey DF, Yang L, Pan JQ, Todorovic SM. Different roles of T-type calcium channel isoforms in hypnosis induced by an endogenous neurosteroid epipregnanolone. Neuropharmacology 2021; 197:108739. [PMID: 34339750 PMCID: PMC8478885 DOI: 10.1016/j.neuropharm.2021.108739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/09/2021] [Accepted: 07/29/2021] [Indexed: 12/31/2022]
Abstract
BACKGROUND Many neuroactive steroids induce sedation/hypnosis by potentiating γ-aminobutyric acid (GABAA) currents. However, we previously demonstrated that an endogenous neuroactive steroid epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one] (EpiP) exerts potent peripheral analgesia and blocks T-type calcium currents while sparing GABAA currents in rat sensory neurons. This study seeks to investigate the behavioral effects elicited by systemic administration of EpiP and to characterize its use as an adjuvant agent to commonly used general anesthetics (GAs). METHODS Here, we utilized electroencephalographic (EEG) recordings to characterize thalamocortical oscillations, as well as behavioral assessment and mouse genetics with wild-type (WT) and different knockout (KO) models of T-channel isoforms to investigate potential sedative/hypnotic and immobilizing properties of EpiP. RESULTS Consistent with increased oscillations in slower EEG frequencies, EpiP induced an hypnotic state in WT mice when injected alone intra-peritoneally (i.p.) and effectively facilitated anesthetic effects of isoflurane (ISO) and sevoflurane (SEVO). The CaV3.1 (Cacna1g) KO mice demonstrated decreased sensitivity to EpiP-induced hypnosis when compared to WT mice, whereas no significant difference was noted between CaV3.2 (Cacna1h), CaV3.3 (Cacna1i) and WT mice. Finally, when compared to WT mice, onset of EpiP-induced hypnosis was delayed in CaV3.2 KO mice but not in CaV3.1 and CaV3.3 KO mice. CONCLUSION We posit that EpiP may have an important role as novel hypnotic and/or adjuvant to volatile anesthetic agents. We speculate that distinct hypnotic effects of EpiP across all three T-channel isoforms is due to their differential expression in thalamocortical circuitry.
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Affiliation(s)
- Ian Coulter
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Tamara Timic Stamenic
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Pierce Eggan
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Brier R. Fine
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Timothy Corrigan
- Department of Pediatrics, Division of Neurology,
Translational Epilepsy Research Program, University of Colorado, Anschutz Medical
Campus, Aurora, CO 80045, USA
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University
School of Medicine, St. Louis, MO 63110, USA;,Taylor Family Institute for Innovative Psychiatric
Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lingling Yang
- Stanley Center for Psychiatric Research, Broad Institute of
Harvard and MIT
| | - Jen Q. Pan
- Stanley Center for Psychiatric Research, Broad Institute of
Harvard and MIT
| | - Slobodan M. Todorovic
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045;,Neuroscience, University of Colorado, Anschutz Medical
Campus, Aurora 80045;,Pharmacology Graduate Programs, University of Colorado,
Anschutz Medical Campus, Aurora 80045
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6
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Yabuki Y, Matsuo K, Yu M, Xu J, Sakimura K, Shioda N, Fukunaga K. Cav3.1 t-type calcium channel is critical for cell proliferation and survival in newly generated cells of the adult hippocampus. Acta Physiol (Oxf) 2021; 232:e13613. [PMID: 33393208 DOI: 10.1111/apha.13613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/29/2020] [Accepted: 12/30/2020] [Indexed: 11/27/2022]
Abstract
AIMS Adult hippocampal neurogenesis plays an important role in neuronal plasticity and maintenance in mammals. Low-threshold voltage-gated T-type calcium channels produce calcium spikes that increase fast action potentials in newborn cells in the hippocampal dentate gyrus (DG); however, their role in adult hippocampal neurogenesis remains unclear. Here, we demonstrate impaired adult hippocampal neurogenesis in Cav3.1T-type calcium channel knockout mice. METHODS AND RESULTS Cav3.1T-type calcium channel was predominantly localized in neuronal progenitor cells of the mouse hippocampal DG. By counting the number of 5-bromo-2'-deoxyuridine-labeled cells, decreased proliferation and survival of newly generated cells were observed in the adult hippocampal DG in Cav3.1 knockout mice as compared to wild-type (WT) mice. Moreover, the degree of maturation of doublecortin-positive cells in Cav3.1 knockout mice was lower than that in WT mice, suggesting that Cav3.1 deletion may impair neuronal differentiation. Consistent with impaired hippocampal neurogenesis, Cav3.1 knockout mice showed decreased social interaction. Reduced phosphorylation levels of calcium/calmodulin-dependent protein kinase II and protein kinase B were closely associated with impaired hippocampal neurogenesis in Cav3.1 knockout mice. Moreover, the mRNA and protein expression levels of brain-derived neurotrophic factor, important for neurogenesis, were significantly decreased in Cav3.1 knockout mice. Finally, gene ontology analysis revealed alterations in genes related to the promotion of cell death/apoptosis and suppression of cell proliferation/neuronal differentiation pathways, including Bdnf. CONCLUSION These results suggest that the Cav3.1T-type calcium channel may be a key molecule required for cell proliferation, survival and neuronal differentiation in newly generated cells of the adult mouse hippocampus.
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Affiliation(s)
- Yasushi Yabuki
- Department of Genomic Neurology Institute of Molecular Embryology and Genetics Kumamoto University Kumamoto Japan
| | - Kazuya Matsuo
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Mengze Yu
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Jing Xu
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology Brain Research InstituteNiigata University Niigata Japan
| | - Norifumi Shioda
- Department of Genomic Neurology Institute of Molecular Embryology and Genetics Kumamoto University Kumamoto Japan
| | - Kohji Fukunaga
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
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7
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Timic Stamenic T, Feseha S, Manzella FM, Wallace D, Wilkey D, Corrigan T, Fiedler H, Doerr P, Krishnan K, Raol YH, Covey DF, Jevtovic-Todorovic V, Todorovic SM. The T-type calcium channel isoform Ca v3.1 is a target for the hypnotic effect of the anaesthetic neurosteroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile. Br J Anaesth 2021; 126:245-255. [PMID: 32859366 PMCID: PMC7844375 DOI: 10.1016/j.bja.2020.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 07/02/2020] [Accepted: 07/08/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The mechanisms underlying the role of T-type calcium channels (T-channels) in thalamocortical excitability and oscillations in vivo during neurosteroid-induced hypnosis are largely unknown. METHODS We used patch-clamp electrophysiological recordings from acute brain slices ex vivo, recordings of local field potentials (LFPs) from the central medial thalamic nucleus in vivo, and wild-type (WT) and Cav3.1 knock-out mice to investigate the molecular mechanisms of hypnosis induced by the neurosteroid analogue (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH). RESULTS Patch-clamp recordings showed that 3β-OH inhibited isolated T-currents but had no effect on phasic or tonic γ-aminobutyric acid A currents. Also in acute brain slices, 3β-OH inhibited the spike firing mode more profoundly in WT than in Cav3.1 knockout mice. Furthermore, 3β-OH significantly hyperpolarised neurones, reduced the amplitudes of low threshold spikes, and diminished rebound burst firing only in WT mice. We found that 80 mg kg-1 i.p. injections of 3β-OH induced hypnosis in >60% of WT mice but failed to induce hypnosis in the majority of mutant mice. A subhypnotic dose of 3β-OH (20 mg kg-1 i.p.) accelerated induction of hypnosis by isoflurane only in WT mice, but had similar effects on the maintenance of isoflurane-induced hypnosis in both WT and Cav3.1 knockout mice. In vivo recordings of LFPs showed that a hypnotic dose of 3β-OH increased δ, θ, α, and β oscillations in WT mice in comparison with Cav3.1 knock-out mice. CONCLUSIONS The Cav3.1 T-channel isoform is critical for diminished thalamocortical excitability and oscillations that underlie neurosteroid-induced hypnosis.
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Affiliation(s)
- Tamara Timic Stamenic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Simon Feseha
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Francesca M Manzella
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA; Neuroscience and Pharmacology Graduate Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Damon Wallace
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Davis Wilkey
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Timothy Corrigan
- Department of Pediatrics, Division of Neurology, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Hanna Fiedler
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Patricia Doerr
- Department of Anesthesiology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Yogendra H Raol
- Department of Pediatrics, Division of Neurology, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, MO, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, Saint Louis, MO, USA
| | | | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA; Neuroscience and Pharmacology Graduate Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
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8
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Georgiev DD. Quantum information theoretic approach to the mind–brain problem. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 158:16-32. [DOI: 10.1016/j.pbiomolbio.2020.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/02/2020] [Accepted: 08/05/2020] [Indexed: 12/25/2022]
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9
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Timic Stamenic T, Feseha S, Valdez R, Zhao W, Klawitter J, Todorovic SM. Alterations in Oscillatory Behavior of Central Medial Thalamic Neurons Demonstrate a Key Role of CaV3.1 Isoform of T-Channels During Isoflurane-Induced Anesthesia. Cereb Cortex 2020; 29:4679-4696. [PMID: 30715245 DOI: 10.1093/cercor/bhz002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/04/2019] [Accepted: 01/08/2019] [Indexed: 11/14/2022] Open
Abstract
Although the central medial nucleus (CeM) of the thalamus is an essential part of the arousal system for sleep and anesthesia initiation, the precise mechanisms that regulate its activity are not well studied. We examined the role of CaV3.1 isoform of T-type calcium channels (T-channels) in the excitability and rhythmic activity of CeM neurons during isoflurane (ISO)-induced anesthesia by using mouse genetics and selective pharmacology. Patch-clamp recordings taken from acute brain slices revealed that CaV3.1 channels in CeM are inhibited by prototypical volatile anesthetic ISO (250 and 500 μM) and selective T-channels blocker 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2). Both TTA-P2 and ISO attenuated tonic and burst firing modes, and hyperpolarized CeM neurons from wild type (WT) mice. These effects were greatly diminished or abolished in CaV3.1 null mice. Our ensuing in vivo local field potential (LFP) recordings from CeM indicated that the ability of TTA-P2 and anesthetic concentrations of ISO to promote δ oscillation was substantially weakened in CaV3.1 null mice. Furthermore, escalating ISO concentrations induced stronger burst-suppression LFP pattern in mutant than in WT mice. Our results demonstrate for the first time the importance of CaV3.1 channels in thalamocortical oscillations from the non-specific thalamic nuclei that underlie clinically important effects of ISO.
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Affiliation(s)
- Tamara Timic Stamenic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Simon Feseha
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Robert Valdez
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Wanzhu Zhao
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Jost Klawitter
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.,Neuroscience Graduate Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
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10
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Abstract
General anesthesia serves a critically important function in the clinical care of human patients. However, the anesthetized state has foundational implications for biology because anesthetic drugs are effective in organisms ranging from paramecia, to plants, to primates. Although unconsciousness is typically considered the cardinal feature of general anesthesia, this endpoint is only strictly applicable to a select subset of organisms that are susceptible to being anesthetized. We review the behavioral endpoints of general anesthetics across species and propose the isolation of an organism from its environment - both in terms of the afferent arm of sensation and the efferent arm of action - as a generalizable definition. We also consider the various targets and putative mechanisms of general anesthetics across biology and identify key substrates that are conserved, including cytoskeletal elements, ion channels, mitochondria, and functionally coupled electrical or neural activity. We conclude with a unifying framework related to network function and suggest that general anesthetics - from single cells to complex brains - create inefficiency and enhance modularity, leading to the dissociation of functions both within an organism and between the organism and its surroundings. Collectively, we demonstrate that general anesthesia is not restricted to the domain of modern medicine but has broad biological relevance with wide-ranging implications for a diverse array of species.
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Affiliation(s)
- Max B Kelz
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Perelman School of Medicine, 3620 Hamilton Walk, 334 John Morgan Building, Philadelphia, PA 19104, USA; Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Translational Research Laboratories, 125 S. 31st St., Philadelphia, PA 19104-3403, USA; Mahoney Institute for Neuroscience, University of Pennsylvania, Clinical Research Building, 415 Curie Blvd, Philadelphia, PA 19104, USA.
| | - George A Mashour
- Department of Anesthesiology, University of Michigan, 7433 Medical Science Building 1, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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11
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Hao X, Ou M, Zhang D, Zhao W, Yang Y, Liu J, Yang H, Zhu T, Li Y, Zhou C. The Effects of General Anesthetics on Synaptic Transmission. Curr Neuropharmacol 2020; 18:936-965. [PMID: 32106800 PMCID: PMC7709148 DOI: 10.2174/1570159x18666200227125854] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/20/2020] [Accepted: 02/26/2020] [Indexed: 02/08/2023] Open
Abstract
General anesthetics are a class of drugs that target the central nervous system and are widely used for various medical procedures. General anesthetics produce many behavioral changes required for clinical intervention, including amnesia, hypnosis, analgesia, and immobility; while they may also induce side effects like respiration and cardiovascular depressions. Understanding the mechanism of general anesthesia is essential for the development of selective general anesthetics which can preserve wanted pharmacological actions and exclude the side effects and underlying neural toxicities. However, the exact mechanism of how general anesthetics work is still elusive. Various molecular targets have been identified as specific targets for general anesthetics. Among these molecular targets, ion channels are the most principal category, including ligand-gated ionotropic receptors like γ-aminobutyric acid, glutamate and acetylcholine receptors, voltage-gated ion channels like voltage-gated sodium channel, calcium channel and potassium channels, and some second massager coupled channels. For neural functions of the central nervous system, synaptic transmission is the main procedure for which information is transmitted between neurons through brain regions, and intact synaptic function is fundamentally important for almost all the nervous functions, including consciousness, memory, and cognition. Therefore, it is important to understand the effects of general anesthetics on synaptic transmission via modulations of specific ion channels and relevant molecular targets, which can lead to the development of safer general anesthetics with selective actions. The present review will summarize the effects of various general anesthetics on synaptic transmissions and plasticity.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Yu Li
- Address correspondence to these authors at the Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu 610041, Sichuan, P.R. China; E-mail: and Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, Sichuan, P.R. China; E-mail:
| | - Cheng Zhou
- Address correspondence to these authors at the Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu 610041, Sichuan, P.R. China; E-mail: and Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, Sichuan, P.R. China; E-mail:
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12
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Lv Y, Dai W, Ge A, Fan Y, Hu G, Zeng Y. Aquaporin-4 knockout mice exhibit increased hypnotic susceptibility to ketamine. Brain Behav 2018; 8:e00990. [PMID: 29745050 PMCID: PMC5991570 DOI: 10.1002/brb3.990] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 02/07/2018] [Accepted: 03/11/2018] [Indexed: 11/06/2022] Open
Abstract
PURPOSE This study examines anesthetic/hypnotic effects of ketamine in AQP4 knockout (KO) and wild-type (WT) mice with the particular focus on neurotransmission. MATERIALS AND METHODS Ketamine (100 mg/kg) was intraperitoneally injected in 16 WT and 16 KO mice. The hypnotic potencies were evaluated by the loss of the righting reflex (LORR). The amino acids neurotransmitter levels in prefrontal cortex were measured by microdialysis. RESULTS This study demonstrated that AQP4 knockout significantly shortened the latency compared with WT mice (98.0 ± 4.2 vs. 138.1 ± 15.0 s, p < .05) and prolonged duration of LORR (884.7 ± 58.6 vs. 562.0 ± 51.7 s, p < .05) compared with WT mice in LORR induced by ketamine. Microdialysis showed that lack of AQP4 markedly decreased glutamate level within 20 min (p < .05) and increased γ-aminobutyric acid (GABA) level within 30-40 min (p < .05) after use of ketamine. Moreover, the levels of taurine were remarkably higher in KO mice than in WT mice, but no obvious differences in aspartate were observed between two genotypes. CONCLUSION AQP4 deficiency led to more susceptibility of mice to ketamine, which is probably due to the modulation of specific neurotransmitters, hinting an essential maintenance of synaptic activity mediated by AQP4 in the action of ketamine.
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Affiliation(s)
- Yunluo Lv
- Department of Anesthesiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Wangshu Dai
- The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University, Clinical Cancer Institute of Nanjing University, Nanjing, China
| | - Ai Ge
- Department of Respiratory Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Fan
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Gang Hu
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Yinming Zeng
- Jiangsu Province Institute of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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Tracy ME, Tesic V, Stamenic TT, Joksimovic SM, Busquet N, Jevtovic-Todorovic V, Todorovic SM. Ca V3.1 isoform of T-type calcium channels supports excitability of rat and mouse ventral tegmental area neurons. Neuropharmacology 2018; 135:343-354. [PMID: 29578032 DOI: 10.1016/j.neuropharm.2018.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
Abstract
Recent data have implicated voltage-gated calcium channels in the regulation of the excitability of neurons within the mesolimbic reward system. While the attention of most research has centered on high voltage L-type calcium channel activity, the presence and role of the low voltage-gated T-type calcium channel (T-channels) has not been well explored. Hence, we investigated T-channel properties in the neurons of the ventral tegmental area (VTA) utilizing wild-type (WT) rats and mice, CaV3.1 knock-out (KO) mice, and TH-eGFP knock-in (KI) rats in acute horizontal brain slices of adolescent animals. In voltage-clamp experiments, we first assessed T-channel activity in WT rats with characteristic properties of voltage-dependent activation and inactivation, as well as characteristic crisscrossing patterns of macroscopic current kinetics. T-current kinetics were similar in WT mice and WT rats but T-currents were abolished in CaV3.1 KO mice. In ensuing current-clamp experiments, we observed the presence of hyperpolarization-induced rebound burst firing in a subset of neurons in WT rats, as well as dopaminergic and non-dopaminergic neurons in TH-eGFP KI rats. Following the application of a pan-selective T-channel blocker TTA-P2, rebound bursting was significantly inhibited in all tested cells. In a behavioral assessment, the acute locomotor increase induced by a MK-801 (Dizocilpine) injection in WT mice was abolished in CaV3.1 KO mice, suggesting a tangible role for 3.1 T-type channels in drug response. We conclude that pharmacological targeting of CaV3.1 isoform of T-channels may be a novel approach for the treatment of disorders of mesolimbic reward system.
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Affiliation(s)
- Matthew E Tracy
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Vesna Tesic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Tamara Timic Stamenic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Srdjan M Joksimovic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Nicolas Busquet
- Department of Neurology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, United States; Neuroscience Graduate Program, University of Colorado, Anschutz Medical Campus, Aurora, United States.
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14
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Bushart DD, Shakkottai VG. Ion channel dysfunction in cerebellar ataxia. Neurosci Lett 2018; 688:41-48. [PMID: 29421541 DOI: 10.1016/j.neulet.2018.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 02/02/2018] [Indexed: 12/31/2022]
Abstract
Cerebellar ataxias constitute a heterogeneous group of disorders that result in impaired speech, uncoordinated limb movements, and impaired balance, often ultimately resulting in wheelchair confinement. Motor dysfunction in ataxia can be attributed to dysfunction and degeneration of neurons in the cerebellum and its associated pathways. Recent work has suggested the importance of cerebellar neuronal dysfunction resulting from mutations in specific ion-channels that regulate membrane excitability in the pathogenesis of cerebellar ataxia in humans. Importantly, even in ataxias not directly due to ion-channel mutations, transcriptional changes resulting in ion-channel dysfunction are tied to motor dysfunction and degeneration in models of disease. In this review, we describe the role that ion-channel dysfunction plays in a variety of cerebellar ataxias, and postulate that a potential therapeutic strategy that targets specific ion-channels exists for cerebellar ataxia.
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Affiliation(s)
- David D Bushart
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor MI, USA
| | - Vikram G Shakkottai
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor MI, USA; Department of Neurology, University of Michigan, 4009 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109, USA.
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15
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Xie SN, Ye H, Li JF, An LX. Sevoflurane neurotoxicity in neonatal rats is related to an increase in the GABAAR α1/GABAAR α2 ratio. J Neurosci Res 2017; 95:2367-2375. [PMID: 28843008 DOI: 10.1002/jnr.24118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 05/23/2017] [Accepted: 06/26/2017] [Indexed: 01/24/2023]
Affiliation(s)
- Si-Ning Xie
- Department of Anesthesiology, Beijing TianTan Hospital; Capital Medical University; No. 6 Tiantan Xili, Dongcheng District Beijing 100050 China
| | - Hong Ye
- Department of Anesthesiology, Beijing TianTan Hospital; Capital Medical University; No. 6 Tiantan Xili, Dongcheng District Beijing 100050 China
| | - Jun-Fa Li
- Department of Neurobiology; Capital Medical University; No. 10 Xi-Tou-Tiao, You’an Men Wai, Fengtai District Beijing 100069 China
| | - Li-Xin An
- Department of Anesthesiology, Beijing TianTan Hospital; Capital Medical University; No. 6 Tiantan Xili, Dongcheng District Beijing 100050 China
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16
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Joksimovic SM, Eggan P, Izumi Y, Joksimovic SL, Tesic V, Dietz RM, Orfila JE, DiGruccio MR, Herson PS, Jevtovic-Todorovic V, Zorumski CF, Todorovic SM. The role of T-type calcium channels in the subiculum: to burst or not to burst? J Physiol 2017; 595:6327-6348. [PMID: 28744923 PMCID: PMC5621493 DOI: 10.1113/jp274565] [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: 04/29/2017] [Accepted: 07/07/2017] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Pharmacological, molecular and genetic data indicate a prominent role of low-voltage-activated T-type calcium channels (T-channels) in the firing activity of both pyramidal and inhibitory interneurons in the subiculum. Pharmacological inhibition of T-channels switched burst firing with lower depolarizing stimuli to regular spiking, and fully abolished hyperpolarization-induced burst firing. Our molecular studies showed that CaV 3.1 is the most abundantly expressed isoform of T-channels in the rat subiculum. Consistent with this finding, both regular-spiking and burst firing patterns were profoundly depressed in the mouse with global deletion of CaV 3.1 isoform of T-channels. Selective inhibition of T-channels and global deletion of CaV 3.1 channels completely suppressed development of long-term potentiation (LTP) in the CA1-subiculum, but not in the CA3-CA1 pathway. ABSTRACT Several studies suggest that voltage-gated calcium currents are involved in generating high frequency burst firing in the subiculum, but the exact nature of these currents remains unknown. Here, we used selective pharmacology, molecular and genetic approaches to implicate Cav3.1-containing T-channels in subicular burst firing, in contrast to several previous reports discounting T-channels as major contributors to subicular neuron physiology. Furthermore, pharmacological antagonism of T-channels, as well as global deletion of CaV3.1 isoform, completely suppressed development of long-term potentiation (LTP) in the CA1-subiculum, but not in the CA3-CA1 pathway. Our results indicate that excitability and synaptic plasticity of subicular neurons relies heavily on T-channels. Hence, T-channels may be a promising new drug target for different cognitive deficits.
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Affiliation(s)
- Srdjan M Joksimovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Pierce Eggan
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Yukitoshi Izumi
- Department of Psychiatry & Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Sonja Lj Joksimovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Vesna Tesic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Robert M Dietz
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - James E Orfila
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Michael R DiGruccio
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Paco S Herson
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Charles F Zorumski
- Department of Psychiatry & Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
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17
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Enhanced Thalamic Spillover Inhibition during Non-rapid-eye-movement Sleep Triggers an Electrocortical Signature of Anesthetic Hypnosis. Anesthesiology 2017; 125:964-978. [PMID: 27552653 DOI: 10.1097/aln.0000000000001307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Alterations in thalamic γ-aminobutyric acid-mediated signaling are thought to underlie the increased frontal α-β frequency electrocortical activity that signals anesthetic-induced loss of consciousness with γ-aminobutyric acid receptor type A (GABAAR)-targeting general anesthetics. The general anesthetic etomidate elicits phasic extrasynaptic GABAAR activation ("spillover" inhibition) at thalamocortical neurons in vitro. We hypothesize that this action of etomidate at the thalamus is sufficient to trigger an increase in frontal α-β frequency electrocortical activity and that this effect of etomidate is fully recapitulated by enhanced thalamic spillover inhibition in vivo. METHODS We recorded electrocortical activity and sleep-wake behavior in freely behaving wild-type (n = 33) and extrasynaptic δ-subunit-containing GABAAR knockout mice (n = 9) during bilateral microperfusion of the thalamus with etomidate and/or other pharmacologic agents that influence GABAAR or T-type Ca channel activity. RESULTS Microperfusion of etomidate into the thalamus elicited an increase in α-β frequency electrocortical activity that occurred only during non-rapid-eye-movement (REM) sleep (11.0 ± 11.8% and 16.0 ± 14.2% greater 8 to 12- and 12 to 30-Hz power, respectively; mean ± SD; both P < 0.031) and was not affected by blockade of thalamic T-type Ca channels. Etomidate at the thalamus also increased spindle-like oscillations during non-REM sleep (4.5 ± 2.4 spindle per minute with etomidate vs. 3.2 ± 1.7 at baseline; P = 0.002). These effects of etomidate were fully recapitulated by enhanced thalamic extrasynaptic GABAAR-mediated spillover inhibition. CONCLUSIONS These findings identify how a prototypic GABAAR-targeting general anesthetic agent can elicit the characteristic brain wave pattern associated with anesthetic hypnosis when acting at the thalamus by promoting spillover inhibition and the necessity of a preexisting non-REM mode of activity in the thalamus to generate this effect.
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18
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Ly R, Bouvier G, Szapiro G, Prosser HM, Randall AD, Kano M, Sakimura K, Isope P, Barbour B, Feltz A. Contribution of postsynaptic T-type calcium channels to parallel fibre-Purkinje cell synaptic responses. J Physiol 2016; 594:915-36. [PMID: 26627919 DOI: 10.1113/jp271623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/01/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS At the parallel fibre-Purkinje cell glutamatergic synapse, little or no Ca(2+) entry takes place through postsynaptic neurotransmitter receptors, although postsynaptic calcium increases are clearly involved in the synaptic plasticity. Postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid postsynaptic Ca(2+) signalling mechanism, making it essential to understand how they contribute to the synaptic signalling. Using a selective T-type calcium channel antagonist, we describe a T-type component of the EPSC that is activated by the AMPA receptor-mediated depolarization of the spine and thus will contribute to the local calcium dynamics. This component can amount up to 20% of the EPSC, and this fraction is maintained even at the high frequencies sometimes encountered in sensory processing. Modelling based on our biophysical characterization of T-type calcium channels in Purkinje cells suggests that the brief spine EPSCs cause the activated T-type channels to deactivate rather than inactivate, enabling repetitive activation. ABSTRACT In the cerebellum, sensory information is conveyed to Purkinje cells (PC) via the granule cell/parallel fibre (PF) pathway. Plasticity at the PF-PC synapse is considered to be a mechanism of information storage in motor learning. The induction of synaptic plasticity in the cerebellum and elsewhere usually involves intracellular Ca(2+) signals. Unusually, postsynaptic Ca(2+) signalling in PF-PC spines does not involve ionotropic glutamatergic receptors because postsynaptic NMDA receptors are absent and the AMPA receptors are Ca(2+) -impermeable; postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid Ca(2+) signalling mechanism. Low-threshold activated T-type calcium channels are present at the synapse, although their contribution to PF-PC synaptic responses is unknown. Taking advantage of 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide, a selective T-type channel antagonist, we show in the mouse that inhibition of these channels reduces PF-PC excitatory postsynaptic currents and excitatory postsynaptic potentials by 15-20%. This contribution was preserved during sparse input and repetitive activity. We characterized the biophysical properties of native T-type channels in young animals and modelled their activation during simulated dendritic excitatory postsynaptic potential waveforms. The comparison of modelled and observed synaptic responses suggests that T-type channels only activate in spines that are strongly depolarized by their synaptic input, a process requiring a high spine neck resistance. This brief and local activation ensures that T-type channels rapidly deactivate, thereby limiting inactivation during repetitive synaptic activity. T-type channels are therefore ideally situated to provide synaptic Ca(2+) entry at PF-PC spines.
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Affiliation(s)
- Romain Ly
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Guy Bouvier
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - German Szapiro
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Haydn M Prosser
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK., Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Andrew D Randall
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK.,School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, UK
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Philippe Isope
- INCI, CNRS UPR 3212, Centre de Neurochimie, Strasbourg, France
| | - Boris Barbour
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Anne Feltz
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
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19
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Inhibition promotes long-term potentiation at cerebellar excitatory synapses. Sci Rep 2016; 6:33561. [PMID: 27641070 PMCID: PMC5027531 DOI: 10.1038/srep33561] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/30/2016] [Indexed: 12/18/2022] Open
Abstract
The ability of the cerebellar cortex to learn from experience ensures the accuracy of movements and reflex adaptation, processes which require long-term plasticity at granule cell (GC) to Purkinje neuron (PN) excitatory synapses. PNs also receive GABAergic inhibitory inputs via GCs activation of interneurons; despite the involvement of inhibition in motor learning, its role in long-term plasticity is poorly characterized. Here we reveal a functional coupling between ionotropic GABAA receptors and low threshold CaV3 calcium channels in PNs that sustains calcium influx and promotes long-term potentiation (LTP) at GC to PN synapses. High frequency stimulation induces LTP at GC to PN synapses and CaV3-mediated calcium influx provided that inhibition is intact; LTP is mGluR1, intracellular calcium store and CaV3 dependent. LTP is impaired in CaV3.1 knockout mice but it is nevertheless recovered by strengthening inhibitory transmission onto PNs; promoting a stronger hyperpolarization via GABAA receptor activation leads to an enhanced availability of an alternative Purkinje-expressed CaV3 isoform compensating for the lack of CaV3.1 and restoring LTP. Accordingly, a stronger hyperpolarization also restores CaV3-mediated calcium influx in PNs from CaV3.1 knockout mice. We conclude that by favoring CaV3 channels availability inhibition promotes LTP at cerebellar excitatory synapses.
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Matsumoto-Makidono Y, Nakayama H, Yamasaki M, Miyazaki T, Kobayashi K, Watanabe M, Kano M, Sakimura K, Hashimoto K. Ionic Basis for Membrane Potential Resonance in Neurons of the Inferior Olive. Cell Rep 2016; 16:994-1004. [PMID: 27425615 DOI: 10.1016/j.celrep.2016.06.053] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/04/2016] [Accepted: 06/12/2016] [Indexed: 11/25/2022] Open
Abstract
Some neurons have the ability to enhance output voltage to input current with a preferred frequency, which is called resonance. Resonance is thought to be a basis for membrane potential oscillation. Although ion channels responsible for resonance have been reported, the precise mechanisms by which these channels work remain poorly understood. We have found that resonance is reduced but clearly present in the inferior olivary neurons of Cav3.1 T-type voltage-dependent Ca(2+) channel knockout (KO) mice. The activation of Cav3.1 channels is strongly membrane potential dependent, but less frequency dependent. Residual resonance in Cav3.1 KO mice is abolished by a hyper-polarization-activated cyclic nucleotide-gated (HCN) channel blocker, ZD7288, and is partially suppressed by voltage-dependent K(+) channel blockers. Resonance is inhibited by ZD7288 in wild-type mice and impaired in HCN1 KO mice, suggesting that the HCN1 channel is essential for resonance. The ZD7288-sensitive current is nearly sinusoidal and strongly frequency dependent. These results suggest that Cav3.1 and HCN1 channels act as amplifying and resonating conductances, respectively.
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Affiliation(s)
- Yoshiko Matsumoto-Makidono
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima 734-8551, Japan
| | - Hisako Nakayama
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima 734-8551, Japan
| | - Miwako Yamasaki
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Taisuke Miyazaki
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Kazuto Kobayashi
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo 113-0033, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Kouichi Hashimoto
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima 734-8551, Japan.
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Zhang H, Wheat H, Wang P, Jiang S, Baghdoyan HA, Neubig RR, Shi XY, Lydic R. RGS Proteins and Gαi2 Modulate Sleep, Wakefulness, and Disruption of Sleep/ Wake States after Isoflurane and Sevoflurane Anesthesia. Sleep 2016; 39:393-404. [PMID: 26564126 DOI: 10.5665/sleep.5450] [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: 06/03/2015] [Accepted: 10/17/2015] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES This study tested the hypothesis that Regulators of G protein Signaling (RGS) proteins contribute to the regulation of wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep, and to sleep disruption caused by volatile anesthetics. METHODS The three groups used in this study included wild-type (WT; n = 7) mice and knock-in mice that were heterozygous (+/GS; n = 7) or homozygous (GS/GS; n = 7) for an RGS-insensitive allele that causes prolonged Gαi2 signaling. Mice were implanted with electrodes for recording sleep and conditioned for 1 week or more to sleep in the laboratory. Using within and between groups designs, 24-h recordings of wakefulness, NREM sleep, and REM sleep were compared across three interventions: (1) baseline (control) and after 3 h of being anesthetized with (2) isoflurane or (3) sevoflurane. RESULTS Baseline recordings during the light phase revealed that relative to WT mice, homozygous RGS-insensitive (GS/GS) mice exhibit significantly increased wakefulness and decreased NREM and REM sleep. During the dark phase, these state-specific differences remained significant but reversed direction of change. After cessation of isoflurane and sevoflurane anesthesia there was a long-lasting and significant disruption of sleep and wakefulness. The durations of average episodes of wakefulness, NREM sleep, and REM sleep were significantly altered as a function of genotype and isoflurane and sevoflurane anesthesia. CONCLUSIONS RGS proteins and Gαi2 play a significant role in regulating states of wakefulness, NREM sleep, and REM sleep. Genotype-specific differences demonstrate that RGS proteins modulate sleep disruption caused by isoflurane and sevoflurane anesthesia. The results also support the conclusion that isoflurane and sevoflurane anesthesia do not satisfy the homeostatic drive for sleep.
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Affiliation(s)
- Hao Zhang
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI.,Department of Anesthesiology, The Second Artillery General Hospital, Beijing, China
| | - Heather Wheat
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - Peter Wang
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - Sha Jiang
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - Helen A Baghdoyan
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI.,Departments of Anesthesiology and Psychology, University of Tennessee, Knoxville, TN
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, Lansing, MI
| | - X Y Shi
- Department of Anesthesiology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Ralph Lydic
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI.,Departments of Anesthesiology and Psychology, University of Tennessee, Knoxville, TN
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Petrenko AB, Yamazaki M, Sakimura K, Kano M, Baba H. Genetic inactivation and prolonged pharmacologic inhibition of monoacylglycerol lipase have opposite effects on anesthetic sensitivity to propofol. Eur J Pharmacol 2015; 765:268-73. [PMID: 26318148 DOI: 10.1016/j.ejphar.2015.08.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 11/26/2022]
Abstract
Monoacylglycerol lipase (MGL) is a major enzyme involved in degradation of the endocannabinoid 2-arachidonoylglycerol (2-AG). Selective inhibitors of MGL are regarded as promising analgesics and anticancer agents. To gain insight into the possible consequences of their prolonged administration for anesthetic action, the effects of several inhalational and intravenous anesthetics were tested in knockout mice lacking the MGL gene in the loss of righting reflex (LORR) assay. Sensitivity to inhalational and most intravenous anesthetics was not altered in knockout mice. However, compared with wild-type littermates, they showed increased sensitivity to the intravenous anesthetic propofol. Permanently elevated levels of 2-AG after MGL knockout are known to cause desensitization of cannabinoid (CB1) receptors, which have been advocated as possible mediators of propofol anesthesia. Therefore, increased sensitivity to propofol in knockout mice at first suggested that 2-AG may potentiate CB1 receptors despite their hypofunction in these animals. Pharmacologic inhibition of MGL also causes desensitization of CB1 receptors, so sensitivity to propofol was tested further in C57BL/6N mice pretreated chronically with the selective MGL inhibitor JZL 184. Contrary to the results in knockout mice, these animals showed drastically reduced sensitivity to propofol. The reason for increased sensitivity to propofol after MGL knockout remains unclear, but may result from changes occurring in these animals during development. However, our results in C57BL/6N mice pretreated with JZL 184 confirmed the role of CB1 receptors in propofol anesthesia advocated previously, and also suggest that prolonged use of MGL inhibitors may be associated with the development of resistance to propofol.
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Affiliation(s)
- Andrey B Petrenko
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
| | - Maya Yamazaki
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Hiroshi Baba
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
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23
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Altered thalamocortical rhythmicity and connectivity in mice lacking CaV3.1 T-type Ca2+ channels in unconsciousness. Proc Natl Acad Sci U S A 2015; 112:7839-44. [PMID: 26056284 DOI: 10.1073/pnas.1420983112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In unconscious status (e.g., deep sleep and anesthetic unconsciousness) where cognitive functions are not generated there is still a significant level of brain activity present. Indeed, the electrophysiology of the unconscious brain is characterized by well-defined thalamocortical rhythmicity. Here we address the ionic basis for such thalamocortical rhythms during unconsciousness. In particular, we address the role of CaV3.1 T-type Ca(2+) channels, which are richly expressed in thalamic neurons. Toward this aim, we examined the electrophysiological and behavioral phenotypes of mice lacking CaV3.1 channels (CaV3.1 knockout) during unconsciousness induced by ketamine or ethanol administration. Our findings indicate that CaV3.1 KO mice displayed attenuated low-frequency oscillations in thalamocortical loops, especially in the 1- to 4-Hz delta band, compared with control mice (CaV3.1 WT). Intriguingly, we also found that CaV3.1 KO mice exhibited augmented high-frequency oscillations during unconsciousness. In a behavioral measure of unconsciousness dynamics, CaV3.1 KO mice took longer to fall into the unconscious state than controls. In addition, such unconscious events had a shorter duration than those of control mice. The thalamocortical interaction level between mediodorsal thalamus and frontal cortex in CaV3.1 KO mice was significantly lower, especially for delta band oscillations, compared with that of CaV3.1 WT mice, during unconsciousness. These results suggest that the CaV3.1 channel is required for the generation of a given set of thalamocortical rhythms during unconsciousness. Further, that thalamocortical resonant neuronal activity supported by this channel is important for the control of vigilance states.
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24
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Augmented tonic pain-related behavior in knockout mice lacking monoacylglycerol lipase, a major degrading enzyme for the endocannabinoid 2-arachidonoylglycerol. Behav Brain Res 2014; 271:51-8. [DOI: 10.1016/j.bbr.2014.05.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 04/30/2014] [Accepted: 05/28/2014] [Indexed: 12/15/2022]
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25
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Fukagawa H, Koyama T, Fukuda K. κ-Opioid receptor mediates the antinociceptive effect of nitrous oxide in mice. Br J Anaesth 2014; 113:1032-8. [PMID: 25086587 DOI: 10.1093/bja/aeu254] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Our previous reports demonstrated that genetic deletion of μ-opioid receptor has no influence on the anaesthetic and antinociceptive effects of nitrous oxide (N2O) in mice, and that an antagonist selective for κ-opioid receptor (KOP), but not that selective for δ-opioid receptor, suppresses the antinociceptive effect of N2O. However, it is not known whether genetic deletion of KOP affects the N2O actions. METHODS We measured the minimum alveolar concentration (MAC) of volatile anaesthetics in the absence and presence of N2O. The antinociceptive action of N2O was tested by an acetic acid-writhing test and a hot-plate test. The number of c-Fos-immunopositive cells in sections from the lumbar spinal cord was counted to test whether the descending inhibitory system participates in the pharmacological action of N2O. The hypnotic action of N2O was assessed by measuring the N2O-induced decrease in the EC50 for loss of the righting reflex (EC50-LORR) of sevoflurane. RESULTS Sevoflurane MAC was not significantly reduced by N2O and its antinociceptive action was almost completely abolished in KOP-knockout (KO) mice. The N2O-induced increase in c-Fos-immunopositive cells in laminae III-IV of the lumbar spinal cord was significant in wild-type (WT), but not in KOP-KO mice. In contrast, sevoflurane EC50-LORR was similarly reduced by N2O in WT and KOP-KO mice. CONCLUSIONS Our study suggests that N2O demonstrates its antinociceptive action and reduces sevoflurane MAC in mice through KOP activation, whereas its hypnotic potency is not dependent on KOP activation.
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Affiliation(s)
- H Fukagawa
- Department of Anesthesia, Kyoto University Hospital, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - T Koyama
- Department of Anesthesia, Kyoto University Hospital, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - K Fukuda
- Department of Anesthesia, Kyoto University Hospital, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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26
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Siwek ME, Müller R, Henseler C, Broich K, Papazoglou A, Weiergräber M. The CaV2.3 R-type voltage-gated Ca2+ channel in mouse sleep architecture. Sleep 2014; 37:881-92. [PMID: 24790266 DOI: 10.5665/sleep.3652] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Voltage-gated Ca(2+) channels (VGCCs) are key elements in mediating thalamocortical rhythmicity. Low-voltage activated (LVA) CaV 3 T-type Ca(2+) channels have been related to thalamic rebound burst firing and to generation of non-rapid eye movement (NREM) sleep. High-voltage activated (HVA) CaV 1 L-type Ca(2+) channels, on the opposite, favor the tonic mode of action associated with higher levels of vigilance. However, the role of the HVA Non-L-type CaV2.3 Ca(2+) channels, which are predominantly expressed in the reticular thalamic nucleus (RTN), still remains unclear. Recently, CaV2.3(-/-) mice were reported to exhibit altered spike-wave discharge (SWD)/absence seizure susceptibility supported by the observation that CaV2.3 mediated Ca(2+) influx into RTN neurons can trigger small-conductance Ca(2+)-activated K(+)-channel type 2 (SK2) currents capable of maintaining thalamic burst activity. Based on these studies we investigated the role of CaV2.3 R-type Ca(2+) channels in rodent sleep. METHODS The role of CaV2.3 Ca(2+) channels was analyzed in CaV2.3(-/-) mice and controls in both spontaneous and artificial urethane-induced sleep, using implantable video-EEG radiotelemetry. Data were analyzed for alterations in sleep architecture using sleep staging software and time-frequency analysis. RESULTS CaV2.3 deficient mice exhibited reduced wake duration and increased slow-wave sleep (SWS). Whereas mean sleep stage durations remained unchanged, the total number of SWS epochs was increased in CaV2.3(-/-) mice. Additional changes were observed for sleep stage transitions and EEG amplitudes. Furthermore, urethane-induced SWS mimicked spontaneous sleep results obtained from CaV2.3 deficient mice. Quantitative Real-time PCR did not reveal changes in thalamic CaV3 T-type Ca(2+) channel expression. The detailed mechanisms of SWS increase in CaV2.3(-/-) mice remain to be determined. CONCLUSIONS Low-voltage activated CaV2.3 R-type Ca(2+) channels in the thalamocortical loop and extra-thalamocortical circuitries substantially regulate rodent sleep architecture thus representing a novel potential target for pharmacological treatment of sleep disorders in the future.
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Affiliation(s)
| | - Ralf Müller
- Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
| | | | - Karl Broich
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Anna Papazoglou
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Marco Weiergräber
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany ; Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
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27
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T-type channel blockade impairs long-term potentiation at the parallel fiber-Purkinje cell synapse and cerebellar learning. Proc Natl Acad Sci U S A 2013; 110:20302-7. [PMID: 24277825 DOI: 10.1073/pnas.1311686110] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
CaV3.1 T-type channels are abundant at the cerebellar synapse between parallel fibers and Purkinje cells where they contribute to synaptic depolarization. So far, no specific physiological function has been attributed to these channels neither as charge carriers nor more specifically as Ca(2+) carriers. Here we analyze their incidence on synaptic plasticity, motor behavior, and cerebellar motor learning, comparing WT animals and mice where T-type channel function has been abolished either by gene deletion or by acute pharmacological blockade. At the cellular level, we show that CaV3.1 channels are required for long-term potentiation at parallel fiber-Purkinje cell synapses. Moreover, basal simple spike discharge of the Purkinje cell in KO mice is modified. Acute or chronic T-type current blockade results in impaired motor performance in particular when a good body balance is required. Because motor behavior integrates reflexes and past memories of learned behavior, this suggests impaired learning. Indeed, subjecting the KO mice to a vestibulo-ocular reflex phase reversal test reveals impaired cerebellum-dependent motor learning. These data identify a role of low-voltage activated calcium channels in synaptic plasticity and establish a role for CaV3.1 channels in cerebellar learning.
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28
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Ishii H, Petrenko AB, Kohno T, Baba H. No evidence for the development of acute analgesic tolerance during and hyperalgesia after prolonged remifentanil administration in mice. Mol Pain 2013; 9:11. [PMID: 23497285 PMCID: PMC3679751 DOI: 10.1186/1744-8069-9-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 02/26/2013] [Indexed: 11/10/2022] Open
Abstract
Background Acute opioid tolerance (AOT) and opioid-induced hyperalgesia (OIH) are undesirable effects of opioids that have been reported in both animals and humans. However, the development of AOT and OIH in cases of potent, short-acting μ-opioid receptor agonist remifentanil administration remains controversial. It has been suggested that the emergence of AOT and OIH by remifentanil could be dose and infusion duration dependent, i.e., low dose and short infusions may lead to negative results. In this study, we determined whether AOT and OIH could be elicited by prolonged, continuous administration of remifentanil at maximally tolerable doses in C57BL/6 mice. Results The analgesic effects of continuously administered remifentanil [by short (1 h) and prolonged (4 h) intraperitoneal infusions] were studied. These experiments involved repeated measurements of thermal thresholds during remifentanil administration. Therefore, particular attention was paid to prevent cumulative tissue injury, which could mimic pronociceptive effects of remifentanil. To exclude the possibility of pseudoAOT during infusion, we used brief cooling of all ipsilateral hindpaws that exhibited analgesic response. Thermal thresholds remained steadily elevated over a 1-h period during continuous administration at infusion rates of 120, 180, and 240 mg/kg/h, which indicated no AOT development. To exclude the possibility of pseudoOIH after infusion, intact contralateral hindpaws were used for all postinfusion threshold measurements. Thermal thresholds at each infusion rate returned to the baseline values within 15 min after the termination of the administration. They did not decrease below the baseline values during 1 h following infusion, which indicated no OIH development. Similar threshold dynamics were also observed for thermal and mechanical testing modalities in animals infused at 120 mg/kg/h for 4 h as well as in animals with rapidly attained and maintained maximum analgesia for 3 h. Conclusions These results suggest that neither intra-infusion AOT nor postinfusion OIH develops in mice receiving continuous remifentanil when the possibility of cumulative tissue injury mimicking AOT or OIH is carefully avoided.
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Affiliation(s)
- Hideaki Ishii
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahi-machi, Chuo-ku 951-8510, Niigata, Japan.
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29
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Eckle VS, Digruccio MR, Uebele VN, Renger JJ, Todorovic SM. Inhibition of T-type calcium current in rat thalamocortical neurons by isoflurane. Neuropharmacology 2012; 63:266-73. [PMID: 22491022 DOI: 10.1016/j.neuropharm.2012.03.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 02/27/2012] [Accepted: 03/16/2012] [Indexed: 10/28/2022]
Abstract
Thalamocortical (TC) neurons provide the major sensory input to the mammalian somatosensory cortex. Decreased activity of these cells may be pivotal in the ability of general anesthetics to induce loss of consciousness and promote sleep (hypnosis). T-type voltage-gated calcium currents (T-currents) have a key function regulating the cellular excitability of TC neurons and previous studies have indicated that volatile general anesthetics may alter the excitability of these neurons. Using a patch-clamp technique, we investigated the mechanisms whereby isoflurane, a common volatile anesthetic, modulates isolated T-currents and T-current-dependent excitability of native TC neurons in acute brain slices of the rat. In voltage-clamp experiments, we found that isoflurane strongly inhibited peak amplitude of T-current, yielding an IC(50) of 1.1 vol-% at physiological membrane potentials. Ensuing biophysical studies demonstrated that inhibition was more prominent at depolarized membrane potentials as evidenced by hyperpolarizing shifts in channel availability curves. In current-clamp experiments we found that isoflurane decreased the rate of depolarization of low-threshold-calcium spikes (LTCSs) and consequently increased the latency of rebound spike firing at the same concentrations that inhibited isolated T-currents. This effect was mimicked by a novel selective T-channel blocker 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2). In contrast, isoflurane and TTA-P2 had minimal effect on resting membrane potential and cell input resistance. We propose that the clinical properties of isoflurane may at least partly be provided by depression of thalamic T-currents.
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Affiliation(s)
- Veit-Simon Eckle
- Department of Anesthesiology, University of Virginia Health System, School of Medicine, Charlottesville, VA, USA
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30
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Jacobson GM, Voss LJ, Melin SM, Cursons RTM, Sleigh JW. The role of connexin36 gap junctions in modulating the hypnotic effects of isoflurane and propofol in mice. Anaesthesia 2011; 66:361-7. [PMID: 21418043 DOI: 10.1111/j.1365-2044.2011.06658.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gap junction blockade is a possible mechanism by which general anaesthetic drugs cause unconsciousness. We measured the sensitivity of connexin36 knockout mice to the hypnotic effects of isoflurane and propofol. The experimental endpoint was recovery of the righting reflex of the anaesthetised animals during 0.2% step-reductions in isoflurane concentration, or following intraperitoneal injection of propofol (100 mg.kg(-1) ). Connexin36 knockout animals were more sensitive to the hypnotic effects of isoflurane than 'normal' wild-type animals. The half maximal effective concentration (EC50) for recovery of righting reflex was 0.37% for connexin36 knockout vs 0.49% for wild-type animals (p < 0.001). For propofol, connnexin36 knockout animals showed more rapid loss of righting reflex than wild-type animals (mean (SD) 2.8 (0.13) vs 3.8 (0.27) min); and young (< 60 days) connexin36 knockout animals remained anaesthetised for longer than young wild-type mice (47.2 (2.9) vs 30.5 (1.7) min; p < 0.00001). These findings suggest that the hypnotic effects of anaesthetic drugs may be moderately enhanced by gap junction blockade.
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Affiliation(s)
- G M Jacobson
- Department of Biological Sciences, Faculty of Science and Engineering, The University of Waikato, Hamilton, New Zealand.
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31
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Orestes P, Todorovic SM. Are neuronal voltage-gated calcium channels valid cellular targets for general anesthetics? Channels (Austin) 2010; 4:518-22. [PMID: 21164281 DOI: 10.4161/chan.4.6.12873] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The effects of anesthetics and analgesics on ion channels have been the subject of intense research since recent reports of direct actions of anesthetic molecules on ion channel proteins. It is now known that ligand-gated channels, particularly γ-amino-butyric acid (GABAA) and N-methyl-D-aspartate (NMDA) receptors, play a key role in mediating anesthetic actions, but these channels are unable to account for all aspects of clinical anesthesia such as loss of consciousness, immobility, analgesia, amnesia, and muscle relaxation. Furthermore, an assortment of voltage-gated and background channels also display anesthetic sensitivity and a key question arises: What role do these other channels play in clinical anesthesia? These channels have overlapping physiological roles and pharmacological profiles, making it difficult to assign aspects of the anesthetic state to individual channel types. Here, we will focus on the function of neuronal voltage-gated calcium channels in mediating the effects of general anesthetics.
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Affiliation(s)
- Peihan Orestes
- Department of Anesthesiology, University of Virginia School of Medicine and Health System, Charlottesville, VA, USA
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32
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Handforth A, Homanics GE, Covey DF, Krishnan K, Lee JY, Sakimura K, Martin FC, Quesada A. T-type calcium channel antagonists suppress tremor in two mouse models of essential tremor. Neuropharmacology 2010; 59:380-7. [PMID: 20547167 DOI: 10.1016/j.neuropharm.2010.05.012] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 05/14/2010] [Accepted: 05/24/2010] [Indexed: 11/17/2022]
Abstract
Essential tremor is a common disorder that lacks molecular targets for therapeutic development. T-type calcium channel activation has been postulated to underlie rhythmicity in the olivo-cerebellar system that is implicated in essential tremor. We therefore tested whether compounds that antagonize T-type calcium channel currents suppress tremor in two mouse models that possess an essential tremor-like pharmacological response profile. Tremor was measured using digitized spectral motion power analysis with harmaline-induced tremor and in the GABA(A) receptor α1 subunit-null model. Mice were given ethosuximide, zonisamide, the neuroactive steroid (3β,5α,17β)-17-hydroxyestrane-3-carbonitrile (ECN), the 3,4-dihydroquinazoline derivative KYS05064, the mibefradil derivative NNC 55-0396, or vehicle. In non-sedating doses, each compound reduced harmaline-induced tremor by at least 50% (range of maximal suppression: 53-81%), and in the GABA(A) α1-null model by at least 70% (range 70-93%). Because the T-type calcium channel Cav3.1 is the dominant subtype expressed in the inferior olive, we assessed the tremor response of Cav3.1-deficient mice to harmaline, and found that null and heterozygote mice exhibit as much tremor as wild-type mice. In addition, ECN and NNC 55-0396 suppressed harmaline tremor as well in Cav3.1-null mice as in wild-type mice. The finding that five T-type calcium antagonists suppress tremor in two animal tremor models suggests that T-type calcium channels may be an appropriate target for essential tremor therapy development. It is uncertain whether medications developed to block only the Cav3.1 subtype would exhibit efficacy.
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Affiliation(s)
- Adrian Handforth
- Neurology Service (W127), Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Los Angeles, CA 90073, USA.
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Functional coupling between mGluR1 and Cav3.1 T-type calcium channels contributes to parallel fiber-induced fast calcium signaling within Purkinje cell dendritic spines. J Neurosci 2009; 29:9668-82. [PMID: 19657020 DOI: 10.1523/jneurosci.0362-09.2009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
T-type voltage-gated calcium channels are expressed in the dendrites of many neurons, although their functional interactions with postsynaptic receptors and contributions to synaptic signaling are not well understood. We combine electrophysiological and ultrafast two-photon calcium imaging to demonstrate that mGluR1 activation potentiates cerebellar Purkinje cell Ca(v)3.1 T-type currents via a G-protein- and tyrosine-phosphatase-dependent pathway. Immunohistochemical and electron microscopic investigations on wild-type and Ca(v)3.1 gene knock-out animals show that Ca(v)3.1 T-type channels are preferentially expressed in Purkinje cell dendritic spines and colocalize with mGluR1s. We further demonstrate that parallel fiber stimulation induces fast subthreshold calcium signaling in dendritic spines and that the synaptic Ca(v)3.1-mediated calcium transients are potentiated by mGluR1 selectively during bursts of excitatory parallel fiber inputs. Our data identify a new fast calcium signaling pathway in Purkinje cell dendritic spines triggered by short burst of parallel fiber inputs and mediated by T-type calcium channels and mGluR1s.
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Herring BE, Xie Z, Marks J, Fox AP. Isoflurane inhibits the neurotransmitter release machinery. J Neurophysiol 2009; 102:1265-73. [PMID: 19515956 DOI: 10.1152/jn.00252.2009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite their importance, the mechanism of action of general anesthetics is still poorly understood. Facilitation of inhibitory GABA(A) receptors plays an important role in anesthesia, but other targets have also been linked to anesthetic actions. Anesthetics are known to suppress excitatory synaptic transmission, but it has been difficult to determine whether they act on the neurotransmitter release machinery itself. By directly elevating [Ca(2+)](i) at neurotransmitter release sites without altering plasma membrane channels or receptors, we show that the commonly used inhalational general anesthetic, isoflurane, inhibits neurotransmitter release at clinically relevant concentrations, in a dose-dependent fashion in PC12 cells and hippocampal neurons. We hypothesized that a SNARE and/or SNARE-associated protein represents an important target(s) for isoflurane. Overexpression of a syntaxin 1A mutant, previously shown in Caenorhabditis elegans to block the behavioral effects of isoflurane, completely eliminated the reduction in neurotransmitter release produced by isoflurane, without affecting release itself, thereby establishing the possibility that syntaxin 1A is an intermediary in isoflurane's ability to inhibit neurotransmitter release.
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Affiliation(s)
- Bruce E Herring
- Department of Neurobiology, Pharmacology and Physiology, University of Chicago, Chicago, Illinois 60637, USA
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Isoflurane-sensitive presynaptic R-type calcium channels contribute to inhibitory synaptic transmission in the rat thalamus. J Neurosci 2009; 29:1434-45. [PMID: 19193890 DOI: 10.1523/jneurosci.5574-08.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Because inhibitory synaptic transmission is a major mechanism of general anesthesia, we examined the effects of isoflurane on properties of GABAergic inhibitory currents in the reticular thalamic nucleus (nRT) in brain slices. The evoked IPSCs (eIPSCs) and spontaneous miniature synaptic currents (mIPSCs) of visualized nRT cells in young and adult rats were recorded. Consistent with postsynaptic effects on GABA(A) receptors, isoflurane prolonged the decay-time constants of both eIPSCs and mIPCSs. Surprisingly, isoflurane completely inhibited the amplitude of eIPSCs at clinically relevant concentrations (IC(50) of 240+/-20 microm), increased the paired-pulse ratio, and decreased the frequency of mIPSCs, indicating that presynaptic mechanisms may also contribute to the effects of isoflurane on IPSCs. The overall effect of isoflurane on eIPSCs in nRT cells was a decrease of net charge-transfer across the postsynaptic membrane. The application of 100 microm nickel (Ni(2+)) and the more specific R-type Ca(2+) channel blocker SNX-482 (0.5 microm) decreased eIPSC amplitudes, increased the paired-pulse ratio, and attenuated isoflurane-induced inhibition of eIPSCs. In addition, isoflurane potently blocked currents in recombinant human Ca(V)2.3 (alpha1E) channels with an IC(50) of 206 +/- 22 mum. Importantly, in vivo electroencephalographic (EEG) recordings in adult Ca(V)2.3 knock-out mice demonstrated alterations in isoflurane-induced burst-suppression activity. Because the thalamus has a key function in processing sensory information, sleep, and cognition, modulation of its GABAergic tone by presynaptic R-type Ca(2+) channels may contribute to the clinical effects of general anesthesia.
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Hwang E, Kim S, Choi JH. Estimating transition point of anesthetic-induced loss of consciousness in mice by detecting motion in response to forced movement. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:4974-4977. [PMID: 19964655 DOI: 10.1109/iembs.2009.5334097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To characterize transition periods of entrance to and emergence from anesthetic-induced unconsciousness in terms of thalamocortical neural activity, we devised a new method estimating a transition point of anesthetic-induced loss of consciousness. The method continuously monitors an animal's head motion in response to forced movement on treadmill and uses the motion signals as a criterion of the transition. Anesthetics were administered via previously secured intraperitoneal injection route in order not to disturb the animal's spontaneous movement. Resulting signals from the motion detector could discriminate the points of entrance into and emergence from the anesthetic-induced unconsciousness with resolution corresponding to the sampling frequency. This method makes it possible to track the anesthetic transition period continuously without contaminating EEGs and LFPs.
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Affiliation(s)
- Eunjin Hwang
- Physics Department, Pohang University of Science and Technology, Pohang, Korea.
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Spontaneous hyperactivity in mutant mice lacking the NMDA receptor GluRε1 subunit is aggravated during exposure to 0.1 MAC sevoflurane and is preserved after emergence from sevoflurane anaesthesia. Eur J Anaesthesiol 2008; 25:953-60. [DOI: 10.1017/s0265021508004626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Orestes P, Bojadzic D, Chow RM, Todorovic SM. Mechanisms and functional significance of inhibition of neuronal T-type calcium channels by isoflurane. Mol Pharmacol 2008; 75:542-54. [PMID: 19038845 DOI: 10.1124/mol.108.051664] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous data have indicated that T-type calcium channels (low-voltage activated T-channels) are potently inhibited by volatile anesthetics. Although the interactions of T-channels with a number of anesthetics have been described, the mechanisms by which these agents modulate channel activity, and the functional consequences of such interactions, are not well studied. Here, we used patch-clamp recordings to explore the actions of a prototypical volatile anesthetic, isoflurane (Iso), on recombinant human Ca(V)3.1 and Ca(V)3.2 isoforms of T-channels. We also performed behavioral testing of anesthetic endpoints in mice lacking Ca(V)3.2. Iso applied at resting channel states blocked current through both isoforms in a similar manner at clinically relevant concentrations (1 minimum alveolar concentration, MAC). Inhibition was more prominent at depolarized membrane potentials (-65 versus -100 mV) as evidenced by hyperpolarizing shifts in channel availability curves and a 2.5-fold decrease in IC(50) values. Iso slowed recovery from inactivation and enhanced deactivation in both Ca(V)3.1 and Ca(V)3.2 in a comparable manner but caused a depolarizing shift in activation curves and greater use-dependent block of Ca(V)3.2 channels. In behavioral tests, Ca(V)3.2 knockout (KO) mice showed significantly decreased MAC in comparison with wild-type (WT) litter mates. KO and WT mice did not differ in loss of righting reflex, but mutant mice displayed a delayed onset of anesthetic induction. We conclude that state-dependent inhibition of T-channel isoforms in the central and peripheral nervous systems may contribute to isoflurane's important clinical effects.
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Affiliation(s)
- Peihan Orestes
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia 22908-0710, USA
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Eger EI, Raines DE, Shafer SL, Hemmings HC, Sonner JM. Is a new paradigm needed to explain how inhaled anesthetics produce immobility? Anesth Analg 2008; 107:832-48. [PMID: 18713892 DOI: 10.1213/ane.0b013e318182aedb] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A paradox arises from present information concerning the mechanism(s) by which inhaled anesthetics produce immobility in the face of noxious stimulation. Several findings, such as additivity, suggest a common site at which inhaled anesthetics act to produce immobility. However, two decades of focused investigation have not identified a ligand- or voltage-gated channel that alone is sufficient to mediate immobility. Indeed, most putative targets provide minimal or no mediation. For example, opioid, 5-HT3, gamma-aminobutyric acid type A and glutamate receptors, and potassium and calcium channels appear to be irrelevant or play only minor roles. Furthermore, no combination of actions on ligand- or voltage-gated channels seems sufficient. A few plausible targets (e.g., sodium channels) merit further study, but there remains the possibility that immobilization results from a nonspecific mechanism.
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Affiliation(s)
- Edmond I Eger
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0464, USA.
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