1
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Brosnan RJ, Ramos K, Aguiar AJDA, Cenani A, Knych HK. Anesthetic Pharmacology of the Mint Extracts L-Carvone and Methyl Salicylate. Pharmacology 2022; 107:167-178. [PMID: 35100605 DOI: 10.1159/000520762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 11/04/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Hydrocarbons with sufficient water solubility allosterically modulate anesthetic-sensitive ion channels. Mint extracts L-carvone and methyl salicylate water solubility exceeds modulation cutoff values for γ-amino butyric acid type A (GABAA) receptors, N-methyl-D-aspartate (NMDA) receptors, and type-2 voltage-gated sodium (Nav1.2) channels. We hypothesized that mint extracts modulate these channels at concentrations that anesthetize rats. METHODS Channels were expressed separately in frog oocytes and studied using 2-electrode voltage clamp techniques at drug concentrations up to 10 mM. Normalized current effects were fit to Hill equations. Mint compounds were formulated in a lipid emulsion and administered IV to rats. When unresponsive to the tail clamp, rats were exsanguinated, and plasma drug concentrations were measured. RESULTS Both mint compounds caused concentration-dependent inhibition of all channels except for methyl salicylate which inhibited GABAA receptors at low concentrations and potentiated at high concentrations. Plasma drug concentrations in anesthetized rats were 7.9 mM for L-carvone and 2.7 mM for methyl salicylate. This corresponded to ≥53% NMDA receptor inhibition and ≥78% Nav1.2 channel inhibition by both compounds and 30% potentiation of GABAA receptors by methyl salicylate. CONCLUSION L-Carvone and methyl salicylate allosterically modulate cell receptor targets important to molecular actions of conventional anesthetics at concentrations that also induce general anesthesia in rats.
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Affiliation(s)
- Robert J Brosnan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Kimberly Ramos
- Department of Animal Biology, University of California, Davis, California, USA
| | | | - Alessia Cenani
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Heather K Knych
- California Animal Health and Food Safety Lab, Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
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2
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Jodko-Piórecka K, Sikora B, Kluzek M, Przybylski P, Litwinienko G. Antiradical Activity of Dopamine, L-DOPA, Adrenaline, and Noradrenaline in Water/Methanol and in Liposomal Systems. J Org Chem 2021; 87:1791-1804. [PMID: 34871499 PMCID: PMC8822484 DOI: 10.1021/acs.joc.1c02308] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
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Catecholamines play
a crucial role in signal transduction and are
also expected to act as endogeneous antioxidants, but the mechanism
of their antioxidant action is not fully understood. Here, we describe
the impact of pH on the kinetics of reaction of four catecholamines
(L-DOPA, dopamine, adrenaline, and noradrenaline) with model 2,2-diphenyl-1-picrylhydrazyl
radical (dpph•) in methanol/water. The increase
in pH from 5.5 to 7.4 is followed by a 2 order of magnitude increase
in the rate constant, e.g., for dopamine (DA) kpH5.5 = 1,200 M–1 s–1 versus kpH7.4 = 170,000 M–1 s–1, and such rate acceleration is attributed to a fast
electron transfer from the DA anion to dpph•. We
also proved that at pH 7.0 DA breaks the peroxidation chain of methyl
linoleate in liposomes assembled from neutral and negatively charged
phospholipids. In contrast to no inhibitory effect during peroxidation
in non-ionic emulsions, in bilayers one molecule of DA traps approximately
four peroxyl radicals, with a rate constant kinh >103 M–1 s–1. Our results from a homogeneous system and bilayers prove that catecholamines
act as effective, radical trapping antioxidants with activity depending
on the ionization status of the catechol moiety, as well as microenvironment:
organization of the lipid system (emulsions vs bilayers) and interactions
of catecholamines with the biomembrane.
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Affiliation(s)
| | - Bożena Sikora
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.,Laboratory of Biological Physics, Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Monika Kluzek
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.,Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Paweł Przybylski
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
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3
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Sun Y, Pham AN, Hider RC, Zheng H, Waite TD. Effectiveness of the Iron Chelator CN128 in Mitigating the Formation of Dopamine Oxidation Products Associated with the Progression of Parkinson's Disease. ACS Chem Neurosci 2020; 11:3646-3657. [PMID: 33143428 DOI: 10.1021/acschemneuro.0c00557] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The occurrence and progression of Parkinson's disease (PD) has been associated with the observation of elevated iron concentrations in the substantia nigra pars compacta (SNpc). While the reasons for the impact of elevated iron concentrations remain unclear, one hypothesis is that the presence of labile iron induces the oxidation of dopamine (DA) to toxic quinones such as aminochrome (DAC) and reactive oxygen species (ROS). As such, one of the proposed therapeutic strategies has been the use of iron chelators such as deferiprone (DFP) (which is recognized to have limitations related to its rapid degradation in the liver) to reduce the concentration of labile iron. In this study, a detailed investigation regarding the novel iron chelator, CN128, was conducted and a kinetic model developed to elucidate the fundamental behavior of this chelator. The results in this work reveal that CN128 is effective in alleviating the toxicity induced by iron and DA to neurons when DA is present at moderate concentrations. When all the iron is chelated by CN128, the formation of DAC and the oxidation of DA can be reduced to levels identical to that in the absence of iron. The production of H2O2 is lower than that generated via the autoxidation of the same amount of DA. However, when severe leakage of DA occurs, the application of CN128 is insufficient to alleviate the associated toxicity. This is attibuted to the less important role of iron in the production of toxic intermediates at high concentrations of DA. CN128 is superior to DFP with regard to the reduction in formation of DAC and elevation in DA concentration. In summary, the results of this study suggest that prodromal application of the chelator CN128 could be effective in preventing the onset and slowing the early stage development of PD symptoms associated with oxidants and toxic intermediates resulting from the iron-mediated oxidation of the neurotransmitter dopamine with CN128 likely to be superior to DFP in view of its greater in vivo availability and less problematic side effects.
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Affiliation(s)
- Yingying Sun
- Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - A. Ninh Pham
- Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Robert C. Hider
- Institute of Pharmaceutical Science, King’s College, London, WC2R 2LS, United Kingdom
| | - Haolin Zheng
- Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - T. David Waite
- Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
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4
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Josey BP, Heinrich F, Silin V, Lösche M. Association of Model Neurotransmitters with Lipid Bilayer Membranes. Biophys J 2020; 118:1044-1057. [PMID: 32032504 DOI: 10.1016/j.bpj.2020.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 11/15/2022] Open
Abstract
Aimed at reproducing the results of electrophysiological studies of synaptic signal transduction, conventional models of neurotransmission are based on the specific binding of neurotransmitters to ligand-gated receptor ion channels. However, the complex kinetic behavior observed in synaptic transmission cannot be reproduced in a standard kinetic model without the ad hoc postulation of additional conformational channel states. On the other hand, if one invokes unspecific neurotransmitter adsorption to the bilayer-a process not considered in the established models-the electrophysiological data can be rationalized with only the standard set of three conformational receptor states that also depend on this indirect coupling of neurotransmitters via their membrane interaction. Experimental verification has been difficult because binding affinities of neurotransmitters to the lipid bilayer are low. We quantify this interaction with surface plasmon resonance to measure equilibrium dissociation constants in neurotransmitter membrane association. Neutron reflection measurements on artificial membranes, so-called sparsely tethered bilayer lipid membranes, reveal the structural aspects of neurotransmitters' association with zwitterionic and anionic bilayers. We thus establish that serotonin interacts nonspecifically with the membrane at physiologically relevant concentrations, whereas γ-aminobutyric acid does not. Surface plasmon resonance shows that serotonin adsorbs with millimolar affinity, and neutron reflectometry shows that it penetrates the membrane deeply, whereas γ-aminobutyric is excluded from the bilayer.
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Affiliation(s)
- Brian P Josey
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland
| | - Vitalii Silin
- Institute for Bioscience and Biotechnology Research, Rockville, Maryland
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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5
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
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Biological
membranes are tricky to investigate. They are complex
in terms of molecular composition and structure, functional
over a wide range of time scales, and characterized
by nonequilibrium conditions. Because of all of these
features, simulations are a great technique to study biomembrane
behavior. A significant part of the functional processes
in biological membranes takes place at the molecular
level; thus computer simulations are the method of
choice to explore how their properties emerge from specific
molecular features and how the interplay among the numerous
molecules gives rise to function over spatial and
time scales larger than the molecular ones. In this
review, we focus on this broad theme. We discuss the current
state-of-the-art of biomembrane simulations that, until
now, have largely focused on a rather narrow picture
of the complexity of the membranes. Given this, we
also discuss the challenges that we should unravel in the
foreseeable future. Numerous features such as the actin-cytoskeleton
network, the glycocalyx network, and nonequilibrium
transport under ATP-driven conditions have so far
received very little attention; however, the potential
of simulations to solve them would be exceptionally high. A
major milestone for this research would be that one day
we could say that computer simulations genuinely research
biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Matti Javanainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo naḿesti 542/2 , 16610 Prague , Czech Republic.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Waldemar Kulig
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Tomasz Róg
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Ilpo Vattulainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland.,MEMPHYS-Center for Biomembrane Physics
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6
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Mukai K, Nagai K, Egawa Y, Ouchi A, Nagaoka SI. Kinetic Study of Aroxyl-Radical-Scavenging and α-Tocopherol-Regeneration Rates of Five Catecholamines in Solution: Synergistic Effect of α-Tocopherol and Catecholamines. J Phys Chem B 2016; 120:7088-97. [PMID: 27346174 DOI: 10.1021/acs.jpcb.6b04285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Detailed kinetic studies have been performed for reactions of aroxyl (ArO(•)) and α-tocopheroxyl (α-Toc(•)) radicals with five catecholamines (CAs) (dopamine (DA), norepinephrine (NE), epinephrine (EN), and 5- and 6-hydroxydopamine (5- and 6-OHDA)) and two catechins (epicatechin (EC) and epigallocatechin gallate (EGCG)) to clarify the free-radical-scavenging activity of CAs. Second-order rate constants (ks and kr) for reactions of ArO(•) and α-Toc(•) radicals with the above antioxidants were measured in 2-propanol/water (5:1, v/v) solution at 25.0 °C, using single- and double-mixing stopped-flow spectrophotometries, respectively. Both the rate constants (ks and kr) increased in the order NE < EN < DA < EC < 5-OHDA < EGCG < 6-OHDA. The ks and kr values of 6-OHDA are large and comparable to the corresponding values of ubiquinol-10 and sodium ascorbate, which show high free-radical-scavenging activity. The ultraviolet-visible absorption of α-Toc(•) (λmax = 428 nm), which was produced by the reaction of α-tocopherol (α-TocH) with ArO(•), disappeared under the coexistence of CAs due to the α-TocH-regeneration reaction. The results suggest that the CAs may contribute to the protection from oxidative damage in nervous systems, by scavenging free radicals (such as lipid peroxyl radical) and regenerating α-TocH from the α-Toc(•) radical.
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Affiliation(s)
- Kazuo Mukai
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Kanae Nagai
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Yoshifumi Egawa
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Aya Ouchi
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Shin-Ichi Nagaoka
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
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7
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Kaur R, Sanan R, Mahajan RK. Probing interactions of neurotransmitters with twin tailed anionic surfactant: A detailed physicochemical study. J Colloid Interface Sci 2016; 469:38-46. [PMID: 26866888 DOI: 10.1016/j.jcis.2016.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/30/2016] [Accepted: 02/02/2016] [Indexed: 11/24/2022]
Abstract
Keeping in view the role of neurotransmitters (NTs) in central nervous system diseases and in controlling various physiological processes, present study is aimed to study the binding of neurotransmitters (NTs) such as norepinephrine hydrochloride (NE) and serotonin hydrochloride (5-HT) with twin tailed surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Spectroscopic and electrochemical measurements combined with microcalorimetric measurements were used to characterize the interactions between AOT and NTs. Meteoric modifications to emission profile and absorption spectra of NTs upon addition of AOT are indicative of the binding of NTs with AOT. Distinct interactional states such as formation of ion-pairs, induced and regular micelles with adsorbed NTs molecules have been observed in different concentration regimes of AOT. The formation of ion-pairs from oppositely charged NTs and AOT is confirmed by the reduced absorbance, quenched fluorescence intensity and decrease in peak current (ipa) as well as shifts in peak potential (Epa) values. The stoichiometry and formation of the NTs-AOT complexes has been judged and the extent of interactions is quantitatively discussed in terms of binding constant (K) and free energy of binding (ΔG°). The enthalpy (ΔH°mic) and free energy of micellization (ΔG°mic) for AOT in presence and absence of NTs are determined from the enthalpy curves.
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Affiliation(s)
- Rajwinder Kaur
- Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, India
| | - Reshu Sanan
- P.G. Department of Chemistry, Khalsa College, Amritsar 143001, India
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8
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Lee DK, Albershardt DJ, Cantor RS. Exploring the mechanism of general anesthesia: kinetic analysis of GABAA receptor electrophysiology. Biophys J 2016; 108:1081-93. [PMID: 25762320 DOI: 10.1016/j.bpj.2014.12.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/10/2014] [Accepted: 12/29/2014] [Indexed: 10/23/2022] Open
Abstract
A kinetic model of the effect of agonist and anesthetics on ligand-gated ion channels, developed in earlier work, is further refined and used to predict traces observed in fast-perfusion electrophysiological studies on recombinant GABAA receptors under a wide range of agonist and/or anesthetic concentrations. The model incorporates only three conformational states (resting, open, and desensitized) but allows for the modulation of the conformational free energy landscape connecting these states resulting from adsorption of agonist and/or anesthetic to the bilayer in which the protein is embedded. The model is shown to reproduce the diverse and complex features of experimental traces remarkably well, including both anesthetic-induced and agonist-induced traces, as well as the modulation of agonist-induced traces by anesthetic, either coapplied or continuously present. The solutions to the kinetic equations, which give the time-dependence of each of the nine protein states (three ligation states for each of the three conformations), describe the flow of probability among these states and thus reveal the kinetic underpinnings of the traces. Many of the parameters in the model, such as the desorption rate constants of anesthetic and agonist, are directly related to model-independent experimental measurements and thus can serve as a definitive test of its validity.
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Affiliation(s)
- Daniel K Lee
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire
| | | | - Robert S Cantor
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire; MEMPHYS Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark.
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9
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Cantor RS. The evolutionary origin of the need to sleep: an inevitable consequence of synaptic neurotransmission? Front Synaptic Neurosci 2015; 7:15. [PMID: 26441631 PMCID: PMC4585021 DOI: 10.3389/fnsyn.2015.00015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/03/2015] [Indexed: 11/13/2022] Open
Abstract
It is proposed that the evolutionary origin of the need to sleep is the removal of neurotransmitters (NTs) that escape reuptake and accumulate in brain interstitial fluid (ISF). Recent work suggests that the activity of ionotropic postsynaptic receptors, rapidly initiated by binding of NTs to extracellular sites, is modulated over longer times by adsorption of these NTs to the lipid bilayers in which the receptors are embedded. This bilayer-mediated mechanism is far less molecularly specific than binding, so bilayer adsorption of NTs that have diffused into synapses for other receptors would modulate their activity as well. Although NTs are recycled by membrane protein reuptake, the process is less than 100% efficient; a fraction escapes the region in which these specific reuptake proteins are localized and eventually diffuses throughout the ISF. It is estimated that even if only 0.1% of NTs escape reuptake, they would accumulate and adsorb to bilayers in synapses of other receptors sufficiently to affect receptor activity, the harmful consequences of which are avoided by sleep: a period of efficient convective clearance of solutes together with greatly reduced synaptic activity.
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Affiliation(s)
- Robert S Cantor
- Burke Laboratory, Department of Chemistry, Dartmouth College Hanover, NH, USA ; Memphys Center for Biomembrane Physics, University of Southern Denmark Odense, Denmark
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10
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Jodko-Piórecka K, Litwinienko G. Antioxidant activity of dopamine and L-DOPA in lipid micelles and their cooperation with an analogue of α-tocopherol. Free Radic Biol Med 2015; 83:1-11. [PMID: 25701434 DOI: 10.1016/j.freeradbiomed.2015.02.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/20/2015] [Accepted: 02/09/2015] [Indexed: 12/16/2022]
Abstract
Oxidative stress contributes to the progression of neurodegenerative diseases and considerable attention has been given to the development of new antioxidant-based therapies aimed at limiting neuronal cell damage. Structural analysis of catecholamine neurotransmitters indicates that these molecules can exhibit antioxidant activity due to the presence of a catechol moiety. This hypothesis is confirmed in cell culture experiments but the mechanism of antioxidant action of catecholamines is not described. Herein, we present quantitative kinetic studies on the effect of dopamine (DA) and L-3,4-dihydroxyphenylalanine (L-DOPA) on the peroxidation of methyl linoleate dispersed in Triton X-100 micelles as a model heterogeneous lipid system. Experiments were performed at extended pH range 4.0-10.0 in order to study how protonation/deprotonation of catecholamine affect its antioxidant activity. At pH 4.0-7.0, the activity of catecholamines is limited to retardation of lipid peroxidation (caused by the reaction of catecholamines with initiating radicals in the aqueous phase). The effective suppression of lipid peroxidation can be achieved by applying catecholamines together with an analogue of α-tocopherol (2,2,5,7,8-pentamethyl-6-hydroxychroman, PMHC). For example, a mixture of 1 μM PMHC with 10 μM L-DOPA causes 18-fold elongation of suppression time as compared to 1 μM PMHC used alone. We suggest that catecholamines together with α-tocopherol efficiently enhance the protection of biological systems from oxidative stress. At pH above 8.0 a prooxidative effect caused by reaction of semiquinone radical anions with molecular oxygen is observed. However, this toxic action can be completely suppressed by PMHC acting as an agent removing the potentially harmful semiquinone radicals from the reaction environment.
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11
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Hong H. Role of Lipids in Folding, Misfolding and Function of Integral Membrane Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 855:1-31. [DOI: 10.1007/978-3-319-17344-3_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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12
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Peters GH, Werge M, Elf-Lind MN, Madsen JJ, Velardez GF, Westh P. Interaction of neurotransmitters with a phospholipid bilayer: a molecular dynamics study. Chem Phys Lipids 2014; 184:7-17. [PMID: 25159594 DOI: 10.1016/j.chemphyslip.2014.08.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/14/2014] [Accepted: 08/22/2014] [Indexed: 11/15/2022]
Abstract
We have performed a series of molecular dynamics simulations to study the interactions between the neurotransmitters (NTs) γ-aminobutyrate (GABA), glycine (GLY), acetylcholine (ACH) and glutamate (GLU) as well as the amidated/acetylated γ-aminobutyrate (GABA(neu)) and the osmolyte molecule glycerol (GOL) with a dipalmitoylphosphatidylcholine (DPPC) bilayer. In agreement with previously published experimental data, we found the lowest membrane affinity for the charged molecules and a moderate affinity for zwitterionic and polar molecules. The affinity can be ranked as follows: ACH-GLU<<GABA<GLY<<GABA(neu)<<GOL. The latter three penetrated the bilayer at most with the deepest location being close to the glycerol backbone of the phospholipids. Even at that position, these solutes were noticeably hydrated and carried ∼30-80% of the bulk water along. The mobility of hydration water at the solute is also affected by the penetration into the bilayer. Two time scales of exchanging water molecules could be determined. In the bulk phase, the hydration layer contains ∼20% slow exchanging water molecules which increases 2-3 times as the solutes entered the bilayer. Our results indicate that there is no intermediate exchange of slow moving water molecules from the solutes to the lipid atoms and vice versa. Instead, the exchange relies on the reservoir of unbounded ("free") water molecules in the interfacial bilayer region. Results from the equilibrium simulations are in good agreement with the results from umbrella sampling simulations, which were conducted for the four naturally occurring NTs. Free energy profiles for ACH and GLU show a minimum of ∼2-3 kJ/mol close to the bilayer interface, while for GABA and GLY, a minimum of respectively ∼2 kJ/mol and ∼5 kJ/mol is observed when these NTs are located in the vicinity of the lipid glycerol backbone. The most important interaction of NTs with the bilayer is the charged amino group of NTs with the lipid phosphate group.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark.
| | - Mikkel Werge
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | | | - Jesper J Madsen
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Gustavo F Velardez
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Peter Westh
- NSM, Research Unit for Functional Biomaterials, Roskilde University, Roskilde 4000, Denmark.
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13
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Harris KD, Weiss M, Zahavi A. Why are neurotransmitters neurotoxic? An evolutionary perspective. F1000Res 2014; 3:179. [PMID: 25580225 PMCID: PMC4288432 DOI: 10.12688/f1000research.4828.2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/01/2014] [Indexed: 02/02/2023] Open
Abstract
In the CNS, minor changes in the concentration of neurotransmitters such as glutamate or dopamine can lead to neurodegenerative diseases. We present an evolutionary perspective on the function of neurotransmitter toxicity in the CNS. We hypothesize that neurotransmitters are selected because of their toxicity, which serves as a test of neuron quality and facilitates the selection of neuronal pathways. This perspective may offer additional explanations for the reduction of neurotransmitter concentration in the CNS with age, and suggest an additional role for the blood-brain barrier. It may also suggest a connection between the specific toxicity of the neurotransmitters released in a specific region of the CNS, and elucidate their role as chemicals that are optimal for testing the quality of cells in that region.
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Affiliation(s)
- Keith D Harris
- Department of Zoology, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Meital Weiss
- Department of Zoology, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Amotz Zahavi
- Department of Zoology, Tel-Aviv University, Tel Aviv, 69978, Israel ; Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, 69978, Israel
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14
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Kopec W, Khandelia H. Reinforcing the membrane-mediated mechanism of action of the anti-tuberculosis candidate drug thioridazine with molecular simulations. J Comput Aided Mol Des 2014; 28:123-34. [DOI: 10.1007/s10822-014-9737-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/19/2014] [Indexed: 10/25/2022]
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15
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Jodko-Piorecka K, Litwinienko G. First experimental evidence of dopamine interactions with negatively charged model biomembranes. ACS Chem Neurosci 2013; 4:1114-22. [PMID: 23662798 DOI: 10.1021/cn4000633] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dopamine is essential for receptor-related signal transduction in mammalian central and peripheral nervous systems. Weak interactions between the neurotransmitter and neuronal membranes have been suggested to modulate synaptic transmission; however, binding forces between dopamine and neuronal membranes have not yet been quantitatively described. Herein, for the first time, we have explained the nature of dopamine interactions with model lipid membranes assembled from neutral 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), negatively charged 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG), and the mixture of these two lipids using isothermal titration calorimetry and differential scanning calorimetry. Dopamine binding to anionic membranes is a thermodynamically favored process with negative enthalpy and positive entropy, quantitatively described by the mole ratio partition coefficient, K. K increases with membrane charge to reach its maximal value, 705.4 ± 60.4 M(-1), for membrane composed from pure DMPG. The contribution of hydrophobic effects to the binding process is expressed by the intrinsic partition coefficient, K(0). The value of K(0) = 74.7 ± 6.4 M(-1) for dopamine/DMPG interactions clearly indicates that hydrophobic effects are 10 times weaker than electrostatic forces in this system. The presence of dopamine decreases the main transition temperature of DMPG, but no similar effect has been observed for DMPC. Basing on these results, we propose a simple electrostatic model of dopamine interactions with anionic membranes with the hydrophobic contribution expressed by K(0). We suggest that dopamine interacts superficially with phospholipid membranes without penetrating into the bilayer hydrocarbon core. The model is physiologically important, since neuronal membranes contain a large (even 20%) fraction of anionic lipids.
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Affiliation(s)
- Katarzyna Jodko-Piorecka
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
- MEMPHYS − Center for
Biomembrane Physics, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230
Odense M, Denmark
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Abstract
Volatile anesthetics serve as useful probes of a conserved biological process that is essential to the proper functioning of the central nervous system. A kinetic and thermodynamic analysis of their unusual pharmacological and physiological characteristics has led to a general, predictive theory in which small molecules that adsorb to membranes modulate ion channel function by altering physical properties of membrane bilayers. A kinetic model that is both parsimonious and falsifiable has been developed to test this mechanism. This theory leads to predictions about the structure, function, origin, and evolution of synapses, the etiology of several diseases and disease symptoms affecting the brain, and the mechanism of action of several drugs that are used therapeutically. Neuronal membranes may offer an appealing drug target, given the large number of compounds that adsorb to interfaces and hence membranes.
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Affiliation(s)
- James M Sonner
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0464, USA.
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Peters GH, Wang C, Cruys-Bagger N, Velardez GF, Madsen JJ, Westh P. Binding of serotonin to lipid membranes. J Am Chem Soc 2013; 135:2164-71. [PMID: 23311719 DOI: 10.1021/ja306681d] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is a prevalent neurotransmitter throughout the animal kingdom. It exerts its effect through the specific binding to the serotonin receptor, but recent research has suggested that neural transmission may also be affected by its nonspecific interactions with the lipid matrix of the synaptic membrane. However, membrane-5-HT interactions remain controversial and superficially investigated. Fundamental knowledge of this interaction appears vital in discussions of putative roles of 5-HT, and we have addressed this by thermodynamic measurements and molecular dynamics (MD) simulations. 5-HT was found to interact strongly with lipid bilayers (partitioning coefficient ~1200 in mole fraction units), and this is highly unusual for a hydrophilic solute like 5-HT which has a bulk, oil-water partitioning coefficient well below unity. It follows that membrane affinity must rely on specific interactions, and the MD simulations identified the salt-bridge between the primary amine of 5-HT and the lipid phosphate group as the most important interaction. This interaction anchored cationic 5-HT in the membrane interface with the aromatic ring system pointing inward and a prevailing residence between the phosphate and the carbonyl groups of the lipid. The unprotonated form of 5-HT shows the opposite orientation, with the primary amine pointing toward the membrane core. Partitioning of 5-HT was found to decrease lipid chain order. These distinctive interactions of 5-HT and model membranes could be related to nonspecific effects of this neurotransmitter.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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Moshkov DA, Pavlik LL, Shubina VS, Parnyshkova EY, Mikheeva IB. Cytoskeletal regulation of the cellular function by dopamine. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350910050118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Wang C, Ye F, Velardez GF, Peters GH, Westh P. Affinity of Four Polar Neurotransmitters for Lipid Bilayer Membranes. J Phys Chem B 2010; 115:196-203. [DOI: 10.1021/jp108368w] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chunhua Wang
- Research Unit for Functional Biomaterials, NSM, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark, Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and MEMPHYS—Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Fengbin Ye
- Research Unit for Functional Biomaterials, NSM, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark, Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and MEMPHYS—Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Gustavo F. Velardez
- Research Unit for Functional Biomaterials, NSM, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark, Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and MEMPHYS—Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Günther H. Peters
- Research Unit for Functional Biomaterials, NSM, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark, Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and MEMPHYS—Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Peter Westh
- Research Unit for Functional Biomaterials, NSM, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark, Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and MEMPHYS—Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Moshkov DA, Abramova MB, Shubina VS, Lavrovskaya VP, Pavlik LL, Lezhnev EI. Effect of Dopamine on Viability of BHK-21 Cells. Bull Exp Biol Med 2010; 149:359-63. [DOI: 10.1007/s10517-010-0946-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Alston TA. Frogs featured prominently in basic science contributing to anesthesiology. ACTA ACUST UNITED AC 2010; 27:21, 24-5. [PMID: 20506759 DOI: 10.1016/s1522-8649(09)50011-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Theodore A Alston
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Shubina VS, Abramova MB, Lavrovskaya VP, Pavlik LL, Lezhnev EI, Moshkov DA. Ultrastructure of BHK-21 cells treated with dopamine. ACTA ACUST UNITED AC 2010. [DOI: 10.1134/s1990519x10010104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Weng Y, Hsu TT, Zhao J, Nishimura S, Fuller GG, Sonner JM. Isovaleric, methylmalonic, and propionic acid decrease anesthetic EC50 in tadpoles, modulate glycine receptor function, and interact with the lipid 1,2-dipalmitoyl-Sn-glycero-3-phosphocholine. Anesth Analg 2009; 108:1538-45. [PMID: 19372333 DOI: 10.1213/ane.0b013e31819cd964] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Elevated concentrations of isovaleric (IVA), methylmalonic (MMA), and propionic acid are associated with impaired consciousness in genetic diseases (organic acidemias). We conjectured that part of the central nervous system depression observed in these disorders was due to anesthetic effects of these metabolites. We tested three hypotheses. First, that these metabolites would have anesthetic-sparing effects, possibly being anesthetics by themselves. Second, that these compounds would modulate glycine and gamma-aminobutyric acid (GABA(A)) receptor function, increasing chloride currents through these channels as potent clinical inhaled anesthetics do. Third, that these compounds would affect physical properties of lipids. METHODS Anesthetic EC(50)s were measured in Xenopus laevis tadpoles. Glycine and GABA(A) receptors were expressed in Xenopus laevis oocytes and studied using two-electrode voltage clamping. Pressure-area isotherms of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers were measured with and without added organic acids. RESULTS IVA acid was an anesthetic in tadpoles, whereas MMA and propionic acid decreased isoflurane's EC(50) by half. All three organic acids concentration-dependently increased current through alpha(1) glycine receptors. There were minimal effects on alpha(1)beta(2)gamma(2s) GABA(A) receptors. The organic acids increased total lateral pressure (surface pressure) of DPPC monolayers, including at mean molecular areas typical of bilayers. CONCLUSION IVA, MMA, and propionic acid have anesthetic effects in tadpoles, positively modulate glycine receptor function and affect physical properties of DPPC monolayers.
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Affiliation(s)
- Yun Weng
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143-0464, USA
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Zhao J, Zhang Y, Eger EI, Sonner J. Intrathecal glycine significantly decreases the minimum alveolar concentration of isoflurane in rats. ACTA ACUST UNITED AC 2009; 23:16-8. [PMID: 18437904 DOI: 10.1016/s1001-9294(09)60003-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To evaluate the effect of intrathecal administration of glycine on the minimum alveolar concentration (MAC) of isoflurane in rats. METHODS Intrathecal catheters were implanted in 40 adult male rats anesthetized with isoflurane. Baseline MAC of isoflurane was measured during the infusion of artificial cerebrospinal fluid (CSF) alone. Subsequently, 10, 40, 80, 160, and 300 mmol/L of glycine dissolved in artificial CSF were infused for two hours at the same rate as under control conditions, and MAC for isoflurane was re-determined. RESULTS Intrathecal administration of glycine produced a significant, dose-dependent decrease in MAC for isoflurane (up to -65.2% +/- 16.2%). CONCLUSIONS Intrathecal administration of glycine decreases anesthetic requirement This result supports the idea that glycine receptors may be important to the immobilizing effect of anesthetics that enhance glycine receptor function such as isoflurane.
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Affiliation(s)
- Jing Zhao
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730.
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Sonner JM. A hypothesis on the origin and evolution of the response to inhaled anesthetics. Anesth Analg 2008; 107:849-54. [PMID: 18713893 DOI: 10.1213/ane.0b013e31817ee684] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this article, I present an evolutionary explanation for why organisms respond to inhaled anesthetics. It is conjectured that organisms today respond to inhaled anesthetics owing to the sensitivity of ion channels to inhaled anesthetics, which in turn has arisen by common descent from ancestral, anesthetic-sensitive ion channels in one-celled organisms (i.e., that the response to anesthetics did not arise as an adaptation of the nervous system, but rather of ion channels that preceded the origin of multicellularity). This sensitivity may have been refined by continuing selection at synapses in multicellular organisms. In particular, it is hypothesized that 1) the beneficial trait that was selected for in one-celled organisms was the coordinated response of ion channels to compounds that were present in the environment, which influenced the conformational equilibrium of ion channels; 2) this coordinated response prevented the deleterious consequences of entry of positive charges into the cell, thereby increasing the fitness of the organism; and 3) these compounds (which may have included organic anions, cations, and zwitterions as well as uncharged compounds) mimicked inhaled anesthetics in that they were interfacially active, and modulated ion channel function by altering bilayer properties coupled to channel function. The proposed hypothesis is consistent with known properties of inhaled anesthetics. In addition, it leads to testable experimental predictions of nonvolatile compounds having anesthetic-like modulatory effects on ion channels and in animals, including endogenous compounds that may modulate ion channel function in health and disease. The latter included metabolites that are increased in some types of end-stage organ failure, and genetic metabolic diseases. Several of these predictions have been tested and proved to be correct.
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Affiliation(s)
- James M Sonner
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143-0464, 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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Yang L, Sonner JM. The anesthetic-like effects of diverse compounds on wild-type and mutant gamma-aminobutyric acid type A and glycine receptors. Anesth Analg 2008; 106:838-45, table of contents. [PMID: 18292428 DOI: 10.1213/ane.0b013e31816095bd] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION No theory of inhaled anesthetic action requires volatility of the anesthetic to accomplish the biophysical interaction of anesthetic with biological target. The identification of mutations that attenuate the effect of inhaled anesthetics on various receptors raises the possibility that nonvolatile compounds with anesthetic effects can be identified with the aid of these receptors. In previous studies, we identified compounds that were either charged or had an exceptionally low vapor pressure and which modulated anesthetic-sensitive receptors in a manner similar to inhaled anesthetics. We tested whether these, and another charged compound, shared a common mechanism with volatile anesthetics, by comparing their effect on wild-type gamma-aminobutyric acid type A (GABA(A)) or glycine receptors and mutant receptors that were engineered to be relatively resistant to inhaled anesthetics. METHODS The effect of beta-hydroxybutyric acid, ammonium chloride, diethylhexyl phthalate, and GABA were tested on homomeric alpha1 and mutant alpha1 (S267I) glycine receptors. The effect of sodium dodecyl sulfate and glycine were tested on alpha1 b2 gamma2s and mutant alpha1(S270I) beta2 gamma2s GABA(A) receptors. Receptors were expressed in Xenopus laevis oocytes and studied using two-electrode voltage clamping. For both GABA(A) and glycine receptors, isoflurane and ethanol were used as positive controls and propofol as a negative control (i.e., unaffected by the mutation). RESULTS Beta-hydroxybutyric acid, ammonium chloride, diethylhexyl phthalate, and GABA all enhanced glycine receptor function. This effect was reduced by the S267I mutations. Sodium dodecyl sulfate and glycine enhanced GABA(A) receptor function, and the S270I mutation attenuated this effect. CONCLUSION These findings support the hypothesis that the compounds studied modulate GABA(A) or glycine receptors by a mechanism similar to that of isoflurane and ethanol. Comparing the effect of drugs on anesthetic-sensitive wild-type receptors with relatively less sensitive mutant receptors may help identify compounds with anesthetic effects.
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Affiliation(s)
- Liya Yang
- Department of Anesthesia and Perioperative Care, Room S-455i, University of California, San Francisco, CA 94143-0464, USA
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