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Zhou Y, Dong W, Qiu YK, Shao KJ, Zhang ZX, Yao JQ, Chen TQ, Li ZY, Zhou CR, Jiao XH, Chen Y, Lu H, Wu YQ. Regulating the activity of GABAergic neurons in the ventral pallidum alters the general anesthesia effect of propofol. Neuropharmacology 2024; 257:110032. [PMID: 38852839 DOI: 10.1016/j.neuropharm.2024.110032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 05/28/2024] [Accepted: 06/06/2024] [Indexed: 06/11/2024]
Abstract
The full mechanism of action of propofol, a commonly administered intravenous anesthetic drug in clinical practice, remains elusive. The focus of this study was the role of GABAergic neurons which are the main neuron group in the ventral pallidum (VP) closely associated with anesthetic effects in propofol anesthesia. The activity of VP GABAergic neurons following propofol anesthesia in Vgat-Cre mice was observed via detecting c-Fos immunoreactivity by immunofluorescence and western blotting. Subsequently, chemogenetic techniques were employed in Vgat-Cre mice to regulate the activity of VP GABAergic neurons. The role of VP GABAergic neurons in generating the effects of general anesthesia induced by intravenous propofol was further explored through behavioral tests of the righting reflex. The results revealed that c-Fos expression in VP GABAergic neurons in Vgat-Cre mice dramatically decreased after propofol injection. Further studies demonstrated that chemogenetic activation of VP GABAergic neurons during propofol anesthesia shortened the duration of anesthesia and promoted wakefulness. Conversely, the inhibition of VP GABAergic neurons extended the duration of anesthesia and facilitated the effects of anesthesia. The results obtained in this study suggested that regulating the activity of GABAergic neurons in the ventral pallidum altered the effect of propofol on general anesthesia.
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Affiliation(s)
- Yue Zhou
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Wei Dong
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Yong-Kang Qiu
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Ke-Jie Shao
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Zi-Xin Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Jia-Qi Yao
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Tian-Qi Chen
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Zi-Yi Li
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Chen-Rui Zhou
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Xin-Hao Jiao
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Yu Chen
- Department of Anesthesiology, Liyang People's Hospital, Jiangsu Province, Liyang, China; Department of Anesthesiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
| | - Han Lu
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Yu-Qing Wu
- Jiangsu Province Key Laboratory of Anesthesiology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China.
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2
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Narattil NR, Maroun M. Differential role of NMDA receptors in hippocampal-dependent spatial memory and plasticity in juvenile male and female rats. Hippocampus 2024. [PMID: 39143939 DOI: 10.1002/hipo.23631] [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: 01/07/2024] [Revised: 05/17/2024] [Accepted: 07/17/2024] [Indexed: 08/16/2024]
Abstract
Early life, or juvenility, stands out as the most pivotal phase in neurodevelopment due to its profound impact over the long-term cognition. During this period, significant changes are made in the brain's connections both within and between different areas, particularly in tandem with the development of more intricate behaviors. The hippocampus is among the brain regions that undergo significant postnatal remodeling, including dendritic arborization, synaptogenesis, the formation of complex spines and neuron proliferation. Given the crucial role of the hippocampus in spatial memory processing, it has been observed that spatial memory abilities continue to develop as the hippocampus matures, particularly before puberty. The N-methyl-d-aspartate (NMDA) type of glutamate receptor channel is crucial for the induction of activity-dependent synaptic plasticity and spatial memory formation in both rodents and humans. Although extensive evidence shows the role of NMDA receptors (NMDAr) in spatial memory and synaptic plasticity, the studies addressing the role of NMDAr in spatial memory of juveniles are sparse and mostly limited to adult males. In the present study, we, therefore, aimed to investigate the effects of systemic NMDAr blockade by the MK-801 on spatial memory (novel object location memory, OLM) and hippocampal plasticity in the form of long-term potentiation (LTP) of both male and female juvenile rats. Our results show the sex-dimorphic role of NMDAr in spatial memory and plasticity during juvenility, as systemic NMDAr blockade impairs the OLM and LTP in juvenile males without an effect on juvenile females. Taken together, our results demonstrate that spatial memory and hippocampal plasticity are NMDAr-dependent in juvenile males and NMDAr-independent in juvenile females. These sex-specific differences in the mechanisms of spatial memory and plasticity may imply gender-specific treatment for spatial memory disorders even in children.
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Affiliation(s)
- Nisha Rajan Narattil
- Sagol Department of Neurobiology, Faculty of Natural Sciences, and the Integrated Brain and Behavior Center, University of Haifa, Haifa, Israel
| | - Mouna Maroun
- Sagol Department of Neurobiology, Faculty of Natural Sciences, and the Integrated Brain and Behavior Center, University of Haifa, Haifa, Israel
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3
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Behrooz AB, Nasiri M, Adeli S, Jafarian M, Pestehei SK, Babaei JF. Pre-adolescence repeat exposure to sub-anesthetic doses of ketamine induces long-lasting behaviors and cognition impairment in male and female rat adults. IBRO Neurosci Rep 2024; 16:211-223. [PMID: 38352700 PMCID: PMC10862408 DOI: 10.1016/j.ibneur.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/28/2023] [Accepted: 01/19/2024] [Indexed: 02/16/2024] Open
Abstract
In pre-adolescence, repeated anesthesia may be required for therapeutic interventions. Adult cognitive and neurobehavioral problems may result from preadolescent exposure to anesthetics. This study examined the long-term morphological and functional effects of repeated sub-anesthetic doses of ketamine exposure on male and female rat adults during pre-adolescence. Weaned 48 pre-adolescent rats from eight mothers and were randomly divided into four equal groups: control group and the ketamine group of males and females (20 mg/kg daily for 14 days); then animals received care for 20-30 days. Repeated exposure to sub-anesthetic doses of ketamine on cognitive functions was assayed using Social discrimination and novel object tests. Besides, an elevated plus maze and fear conditioning apparatus were utilized to determine exploratory and anxiety-like behavior in adults. Toluidine blue stain was used to evaluate the number of dead neurons in the hippocampus, and the effects of ketamine on synaptic plasticity were compared in the perforant pathway of the CA1 of the hippocampus. Our study indicates that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can result in neurobehavioral impairment in male and female rat adulthood but does not affect anxiety-like behavior. We found a significant quantifiable increase in dark neurons. Recorded electrophysiologically, repeat sub-anesthetic doses of ketamine resulted in hampering long-term potentiation and pair pulse in male adult animals. Our results showed that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can induce hippocampus and neuroplasticity changes later in adulthood. This study opens up a new line of inquiry into potential adverse outcomes of repeated anesthesia exposure in pre-adolescent rats.
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Affiliation(s)
- Amir Barzegar Behrooz
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahdieh Nasiri
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Soheila Adeli
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Jafarian
- Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Khalil Pestehei
- Department of Anesthesiology, Tehran University of Medical Sciences, Tehran, Iran
- Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Javad Fahanik Babaei
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
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4
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Müller CP. Serotonin and Consciousness-A Reappraisal. Behav Brain Res 2022; 432:113970. [PMID: 35716774 DOI: 10.1016/j.bbr.2022.113970] [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: 03/18/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 11/02/2022]
Abstract
The serotonergic system of the brain is a major modulator of behaviour. Here we describe a re-appraisal of its function for consciousness based on anatomical, functional and pharmacological data. For a better understanding, the current model of consciousness is expanded. Two parallel streams of conscious flow are distinguished. A flow of conscious content and an affective consciousness flow. While conscious content flow has its functional equivalent in the activity of higher cortico-cortical and cortico-thalamic networks, affective conscious flow originates in segregated deeper brain structures for single emotions. It is hypothesized that single emotional networks converge on serotonergic and other modulatory transmitter neurons in the brainstem where a bound percept of an affective conscious flow is formed. This is then dispersed to cortical and thalamic networks, where it is time locked with conscious content flow at the level of these networks. Serotonin acts in concert with other modulatory systems of the brain stem with some possible specialization on single emotions. Together, these systems signal a bound percept of affective conscious flow. Dysfunctions in the serotonergic system may not only give rise to behavioural and somatic symptoms, but also essentially affect the coupling of conscious affective flow with conscious content flow, leading to the affect-stained subjective side of mental disorders like anxiety, depression, or schizophrenia. The present model is an attempt to integrate the growing insights into serotonergic system function. However, it is acknowledged, that several key claims are still at a heuristic level that need further empirical support.
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Affiliation(s)
- Christian P Müller
- Department of Psychiatry and Psychotherapy, University Clinic, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 6, 91054, Erlangen, Germany; Centre for Drug Research, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.
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5
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Chen K, Hu Q, Gupta R, Stephens J, Xie Z, Yang G. Inhibition of unfolded protein response prevents post-anesthesia neuronal hyperactivity and synapse loss in aged mice. Aging Cell 2022; 21:e13592. [PMID: 35299279 PMCID: PMC9009124 DOI: 10.1111/acel.13592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/18/2022] [Accepted: 03/07/2022] [Indexed: 12/21/2022] Open
Abstract
Delirium is the most common postoperative complication in older patients after prolonged anesthesia and surgery and is associated with accelerated cognitive decline and dementia. The neuronal pathogenesis of postoperative delirium is largely unknown. The unfolded protein response (UPR) is an adaptive reaction of cells to perturbations in endoplasmic reticulum function. Dysregulation of UPR has been implicated in a variety of diseases including Alzheimer's disease and related dementias. However, whether UPR plays a role in anesthesia-induced cognitive impairment remains unexplored. By performing in vivo calcium imaging in the mouse frontal cortex, we showed that exposure of aged mice to the inhalational anesthetic sevoflurane for 2 hours resulted in a marked elevation of neuronal activity during recovery, which lasted for at least 24 hours after the end of exposure. Concomitantly, sevoflurane anesthesia caused a prolonged increase in phosphorylation of PERK and eIF2α, the markers of UPR activation. Genetic deletion or pharmacological inhibition of PERK prevented neuronal hyperactivity and memory impairment induced by sevoflurane. Moreover, we showed that PERK suppression also reversed various molecular and synaptic changes induced by sevoflurane anesthesia, including alterations of synaptic NMDA receptors, tau protein phosphorylation, and dendritic spine loss. Together, these findings suggest that sevoflurane anesthesia causes abnormal UPR in the aged brain, which contributes to neuronal hyperactivity, synapse loss and cognitive decline in aged mice.
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Affiliation(s)
- Kai Chen
- Department of Anesthesiology Columbia University Irving Medical Center New York New York USA
| | - Qiuping Hu
- Department of Anesthesiology Columbia University Irving Medical Center New York New York USA
| | - Riya Gupta
- Barnard College of Columbia University New York New York USA
| | | | - Zhongcong Xie
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine Massachusetts General Hospital and Harvard Medical School Charlestown Massachusetts USA
| | - Guang Yang
- Department of Anesthesiology Columbia University Irving Medical Center New York New York USA
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6
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Platholi J, Hemmings HC. Effects of general anesthetics on synaptic transmission and plasticity. Curr Neuropharmacol 2021; 20:27-54. [PMID: 34344292 PMCID: PMC9199550 DOI: 10.2174/1570159x19666210803105232] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/22/2022] Open
Abstract
General anesthetics depress excitatory and/or enhance inhibitory synaptic transmission principally by modulating the function of glutamatergic or GABAergic synapses, respectively, with relative anesthetic agent-specific mechanisms. Synaptic signaling proteins, including ligand- and voltage-gated ion channels, are targeted by general anesthetics to modulate various synaptic mechanisms, including presynaptic neurotransmitter release, postsynaptic receptor signaling, and dendritic spine dynamics to produce their characteristic acute neurophysiological effects. As synaptic structure and plasticity mediate higher-order functions such as learning and memory, long-term synaptic dysfunction following anesthesia may lead to undesirable neurocognitive consequences depending on the specific anesthetic agent and the vulnerability of the population. Here we review the cellular and molecular mechanisms of transient and persistent general anesthetic alterations of synaptic transmission and plasticity.
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Affiliation(s)
- Jimcy Platholi
- Cornell University Joan and Sanford I Weill Medical College Ringgold standard institution - Anesthesiology New York, New York. United States
| | - Hugh C Hemmings
- Cornell University Joan and Sanford I Weill Medical College Ringgold standard institution - Anesthesiology New York, New York. United States
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7
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Kutsarova S, Mehmed A, Cherkezova D, Stoeva S, Georgiev M, Petkov T, Chapkanov A, Schultz TW, Mekenyan OG. Automated read-across workflow for predicting acute oral toxicity: I. The decision scheme in the QSAR toolbox. Regul Toxicol Pharmacol 2021; 125:105015. [PMID: 34293429 DOI: 10.1016/j.yrtph.2021.105015] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/17/2021] [Accepted: 07/15/2021] [Indexed: 11/17/2022]
Abstract
A decision-scheme outlining the steps for identifying the appropriate chemical category and subsequently appropriate tested source analog(s) for data gap filling of a target chemical by read-across is described. The primary features used in the grouping of the target chemical with source analogues within a database of 10,039 discrete organic substances include reactivity mechanisms associated with protein interactions and specific-acute-oral-toxicity-related mechanisms (e.g., mitochondrial uncoupling). Additionally, the grouping of chemicals making use of the in vivo rat metabolic simulator and neutral hydrolysis. Subsequently, a series of structure-based profilers are used to narrow the group to the most similar analogues. The scheme is implemented in the OECD QSAR Toolbox, so it automatically predicts acute oral toxicity as the rat oral LD50 value in log [1/mol/kg]. It was demonstrated that due to the inherent variability in experimental data, classification distribution should be employed as more adequate in comparison to the exact classification. It was proved that the predictions falling in the adjacent GSH categories to the experimentally-stated ones are acceptable given the variation in experimental data. The model performance estimated by adjacent accuracy was found to be 0.89 and 0.54 while based on R2. The mechanistic and predictive coverages were >0.85.
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Affiliation(s)
- Stela Kutsarova
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Aycel Mehmed
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Daniela Cherkezova
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Stoyanka Stoeva
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Marin Georgiev
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Todor Petkov
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Atanas Chapkanov
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria
| | - Terry W Schultz
- The University of Tennessee, College of Veterinary Medicine, Knoxville, TN, 37996-4500, USA
| | - Ovanes G Mekenyan
- Laboratory of Mathematical Chemistry, Prof. As. Zlatarov University, Bourgas, Bulgaria.
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8
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Effects of urethane and isoflurane on the sensory evoked response and local blood flow in the early postnatal rat somatosensory cortex. Sci Rep 2021; 11:9567. [PMID: 33953244 PMCID: PMC8099888 DOI: 10.1038/s41598-021-88461-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 03/31/2021] [Indexed: 01/01/2023] Open
Abstract
Functional studies in the central nervous system are often conducted using anesthesia. While the dose-dependent effects of anesthesia on neuronal activity have been extensively characterized in adults, little is known about the effects of anesthesia on cortical activity and cerebral blood flow in the immature central nervous system. Substitution of electrophysiological recordings with the less-invasive technique of optical intrinsic signal imaging (OIS) in vivo allowed simultaneous recordings of sensory-evoked functional response and local blood flow changes in the neonatal rat barrel cortex. Using OIS we characterize the effects of two widely used anesthetics—urethane and isoflurane. We found that both anesthetics suppressed the sensory-evoked optical intrinsic signal in a dose-dependent manner. Dependence of the cortical response suppression matched the exponential decay model. At experimental levels of anesthesia, urethane affected the evoked cortical response less than isoflurane, which is in agreement with the results of electrophysiological recordings demonstrated by other authors. Changes in oxygenation and local blood flow also showed negative correlation with both anesthetics. The high similarity in immature patterns of activity recorded in different regions of the developing cortex suggested similar principles of development regardless of the cortical region. Therefore the indicated results should be taken into account during functional explorations in the entire developing cortex. Our results also point to urethane as the anesthetic of choice in non-survival experimental recordings in the developing brain as it produces less prominent impairment of cortical neuronal activity in neonatal animals.
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Abstract
In the last 15 years, a debate has emerged about the validity of the famous Hodgkin-Huxley model for nerve impulse. Mechanical models have been proposed. This note reviews the experimental properties of the nerve impulse and discusses the proposed alternatives. The experimental data, which rule out some of the alternative suggestions, show that while the Hodgkin-Huxley model may not be complete, it nevertheless includes essential features that should not be overlooked in the attempts made to improve, or supersede, it.
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Affiliation(s)
- Michel Peyrard
- Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Cédex 07, Lyon, France.
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10
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Hussein RA, Ahmed M, Sticht H, Breitinger HG, Breitinger U. Fine-Tuning of Neuronal Ion Channels-Mapping of Residues Involved in Glucose Sensitivity of Recombinant Human Glycine Receptors. ACS Chem Neurosci 2020; 11:3474-3483. [PMID: 33007159 DOI: 10.1021/acschemneuro.0c00566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The inhibitory glycine receptor (GlyR) mediates synaptic inhibition in the spinal cord, brain stem, and other regions of the mammalian central nervous system. Glucose was shown to potentiate α1 GlyRs by interacting with K143. Here, additional amino acids involved in glucose modulation were identified using a structure-based approach of site-directed mutagenesis followed by whole-cell patch-clamp analysis. We identified two additional lysine residues in the α1 GlyR extracellular domain, K16 and K281, that were involved in glucose modulation. Mutation of either residue to alanine abolished glucose potentiation. Residue K281 is located in the same pocket as K143 and could thus contribute to glucose binding. The double mutant K143A-K281A showed a 6-fold increase of EC50, while EC50 of both single mutants K143A and K281A was only slightly increased (1.7- and 1.3-fold, respectively). K16 is located at an analgesic binding site that is distant from the agonist or glucose sites, and the K16A mutation may generate a receptor species that is not potentiated. GlyR position α1-S267 is close to the postulated glucose binding site and known for interactions with ethanol and anesthetics. In the presence of glucose, GlyR α1 mutants S267A, S267I, and S267R showed potentiation, no effect, and reduction of current responses, respectively. This pattern follows that of ethanol modulation and suggests that the interaction sites of glucose and ethanol are identical or located close to each other. Our results support the presence of a distinct binding site for glucose on the glycine receptor, overlapping with the ivermectin/ethanol binding pocket near the transmembrane region and the TM2-3 loop.
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Affiliation(s)
- Rama Ashraf Hussein
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Marwa Ahmed
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany
| | - Hans-Georg Breitinger
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Ulrike Breitinger
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
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11
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Victorino DB, Scott-McKean JJ, Johnson MW, Costa ACS. Quantitative Analysis of Retinal Structure and Function in Two Chromosomally Altered Mouse Models of Down Syndrome. Invest Ophthalmol Vis Sci 2020; 61:25. [PMID: 32416604 PMCID: PMC7405684 DOI: 10.1167/iovs.61.5.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Purpose Ophthalmic disorders are among the most prevalent Down syndrome (DS) comorbidities. Therefore, when studying mouse models of DS, ignoring how vision is affected can lead to misinterpretation of results from assessments dependent on the integrity of the visual system. Here, we used imaging and electroretinography (ERG) to study eye structure and function in two important mouse models of DS: Ts65Dn and Dp(16)1Yey/+. Methods Cornea and anterior segment were examined with a slit-lamp. Thickness of retinal layers was quantified by optical coherence tomography (OCT). Eye and lens dimensions were measured by magnetic resonance imaging (MRI). Retinal vasculature parameters were assessed by bright field and fluorescent imaging, and by retinal flat-mount preparations. Ganzfeld ERG responses to flash stimuli were used to assess retinal function in adult mice. Results Total retinal thickness is significantly increased in Ts65Dn and Dp(16)1Yey/+ compared with control mice, because of increased thickness of inner retinal layers, including the inner nuclear layer (INL). Increased retinal vessel caliber was found in both chromosomally altered mice when compared with controls. ERG responses in Ts65Dn and Dp(16)1Yey/+ mice showed subtle alterations compared with controls. These, however, seemed to be unrelated to the thickness of the INL, but instead dependent on the anesthetic agent used (ketamine, tribromoethanol, or urethane). Conclusions We provide evidence of retinal alterations in Ts65Dn and Dp(16)1Yey/+ mice that are similar to those reported in persons with DS. Our ERG results are also a reminder that consideration should be given to the choice of anesthetic agents in such experiments.
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12
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Li C, Yan J, Tang D, Zhu J, Huang C, Sun Y, Hu R, Wang H, Fu C, Chen Y, Jiang H. GluN2A-selective positive allosteric modulator-nalmefene-flumazenil reverses ketamine-fentanyl-dexmedetomidine-induced anesthesia and analgesia in rats. Sci Rep 2020; 10:5265. [PMID: 32210319 PMCID: PMC7093419 DOI: 10.1038/s41598-020-62192-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/10/2020] [Indexed: 11/09/2022] Open
Abstract
Anesthetics are used to produce hypnosis and analgesic effects during surgery, but anesthesia for a long time after the operation is not conducive to the recovery of animals or patients. Therefore, finding appropriate treatments to counter the effects of anesthetics could enhance postoperative recovery. In the current study, we discovered the novel role of a GluN2A-selective positive allosteric modulator (PAM) in ketamine-induced anesthesia and investigated the effects of the PAM combined with nalmefene and flumazenil (PNF) in reversing the actions of an anesthetic combination (ketamine-fentanyl-dexmedetomidine, KFD). PAM treatment dose-dependently decreased the duration of the ketamine-induced loss of righting reflex (LORR). Compared with those in the KFD group, the duration of LORR and the analgesic effect of the KFD + PNF group were obviously decreased. Meanwhile, successive administration of PNF and KFD had no adverse effects on the cardiovascular and respiratory systems. Both the KFD group and the KFD + PNF group showed no changes in hepatic and renal function or cognitive function in rats. Moreover, the recovery of motor coordination of the KFD + PNF group was faster than that of the KFD group. In summary, our results suggest the potential application of the PNF combination as an antagonistic treatment strategy for anesthesia.
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Affiliation(s)
- Chunzhu Li
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China
| | - Jia Yan
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China
| | - Dewei Tang
- Center for Molecular Imaging, Shanghai University of Medicine & Health Sciences, Shanghai, China.,Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Jidong Zhu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chen Huang
- College of Medical Imaging and Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai, 201318, China
| | - Yu Sun
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China
| | - Rong Hu
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China
| | - Hao Wang
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China
| | - Chaoying Fu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yelin Chen
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Hong Jiang
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Center for Specialty Strategy Research of Shanghai Jiao Tong University China Hospital Development Institute, Shanghai, 200011, China.
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Inhibition by general anesthetic propofol of compound action potentials in the frog sciatic nerve and its chemical structure. Naunyn Schmiedebergs Arch Pharmacol 2018; 392:359-369. [PMID: 30519707 DOI: 10.1007/s00210-018-01596-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/27/2018] [Indexed: 02/07/2023]
Abstract
Although the intravenous general anesthetic propofol (2,6-diisopropylphenol) has an ability to inhibit nerve conduction, this has not been fully examined. Various agents inhibit compound action potentials (CAPs) in a manner dependent on their chemical structures. To determine propofol's chemical structure that is important in nerve conduction inhibition, we examined the effects of propofol and its related compounds on fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Propofol concentration-dependently reduced the peak amplitude of the CAP with a half-maximal inhibitory concentration (IC50) value of 0.14 mM. A similar inhibition was produced by other phenols, 4-sec-butylphenol and 4-amylphenol (IC50 values: 0.33 and 0.20 mM, respectively). IC50 values for these and more phenols (4-isopropylphenol, 4-tert-butylphenol, and 4-ter-amylphenol; data published previously) were correlated with the logarithm of their octanol-water partition coefficients. A phenol having ketone group (raspberry ketone) and alcohols (3-phenyl-1-propanol and 2-phenylethylalcohol) inhibited CAPs less effectively than the above-mentioned phenols. The local anesthetic (LA) benzocaine reduced CAP peak amplitudes with an IC50 of 0.80 mM, a value larger than that of propofol. When compared with other LAs, propofol activity was close to those of ropivacaine, levobupivacaine, and pramoxine, while benzocaine activity was similar to those of cocaine and lidocaine. It is concluded that propofol inhibits nerve conduction, possibly owing to isopropyl and hydroxyl groups bound to the benzene ring of propofol and to its lipophilicity; propofol's efficacy is comparable to those of some LAs. These results could serve to develop propofol-related agents exhibiting analgesia when applied topically.
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14
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Chai D, Cheng Y, Jiang H. Fundamentals of fetal toxicity relevant to sevoflurane exposures during pregnancy. Int J Dev Neurosci 2018; 72:31-35. [DOI: 10.1016/j.ijdevneu.2018.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/10/2018] [Accepted: 11/12/2018] [Indexed: 02/08/2023] Open
Affiliation(s)
- Dongdong Chai
- Department of Anesthesiology and Critical Care MedicineShanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Yanyong Cheng
- Department of Anesthesiology and Critical Care MedicineShanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Hong Jiang
- Department of Anesthesiology and Critical Care MedicineShanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghaiChina
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15
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Oakes V, Domene C. Capturing the Molecular Mechanism of Anesthetic Action by Simulation Methods. Chem Rev 2018; 119:5998-6014. [DOI: 10.1021/acs.chemrev.8b00366] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Victoria Oakes
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
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16
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Abstract
Anesthetics can interact with a wide variety of proteins in the body, including ion channels and alter their activity, but little is known about the molecular mechanisms of the interactions responsible for the functional activity. Characterization of the nature of anesthetic-protein interactions therefore is important and requires the complete analysis of the binding energetics. Isothermal titration calorimetry (ITC) is the only technique that allows quantitative determination of all thermodynamic parameters, including the equilibrium binding constant (KB), the standard Gibbs free energy change (ΔG), the enthalpy change (ΔH), the entropy change (ΔS), heat capacity change (ΔCp), and stoichiometry (n) of the reaction. ITC does not require any labeling or modification of the interacting partners analyzed and can be performed in solution with small amounts of reagents. In this chapter we describe the general properties of the ITC method, highlighting some critical aspects of experimental planning and data analysis, with practical application to anesthetic-protein interactions.
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17
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Huang L, Cichon J, Ninan I, Yang G. Post-anesthesia AMPA receptor potentiation prevents anesthesia-induced learning and synaptic deficits. Sci Transl Med 2017; 8:344ra85. [PMID: 27334260 DOI: 10.1126/scitranslmed.aaf7151] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/23/2016] [Indexed: 11/02/2022]
Abstract
Accumulating evidence has shown that repeated exposure to general anesthesia during critical stages of brain development results in long-lasting behavioral deficits later in life. To date, there has been no effective treatment to mitigate the neurotoxic effects of anesthesia on brain development. By performing calcium imaging in the mouse motor cortex, we show that ketamine anesthesia causes a marked and prolonged reduction in neuronal activity during the period of post-anesthesia recovery. Administration of the AMPAkine drug CX546 [1-(1,4-benzodioxan-6-ylcarbonyl)piperidine] to potentiate AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor activity during emergence from anesthesia in mice enhances neuronal activity and prevents long-term motor learning deficits induced by repeated neonatal anesthesia. In addition, we show that CX546 administration also ameliorates various synaptic deficits induced by anesthesia, including reductions in synaptic expression of NMDA (N-methyl-d-aspartate) and AMPA receptor subunits, motor training-evoked neuronal activity, and dendritic spine remodeling associated with motor learning. Together, our results indicate that pharmacologically enhancing neuronal activity during the post-anesthesia recovery period could effectively reduce the adverse effects of early-life anesthesia.
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Affiliation(s)
- Lianyan Huang
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Joseph Cichon
- Medical Scientist Training Program at New York University School of Medicine, New York, NY 10016, USA
| | - Ipe Ninan
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA
| | - Guang Yang
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, New York University School of Medicine, New York, NY 10016, USA.
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18
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Effects of Individual and Combined Pesticide Commercial Formulations Exposure to Egestion and Movement of Common Freshwater Snails, Physa acuta and Helisoma anceps. AMERICAN MIDLAND NATURALIST 2017. [DOI: 10.1674/0003-0031-178.1.97] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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19
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Pan B, Cheng Z, Kong G, Song Z, Wang Y, Wei L, Xiao D, Zhao Y, Guo Q. Propofol inhibits expression of angiotensin II receptor type 2 in dorsal root ganglion neurons. Exp Ther Med 2017; 13:867-872. [PMID: 28450911 PMCID: PMC5403460 DOI: 10.3892/etm.2017.4040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/04/2016] [Indexed: 11/10/2022] Open
Abstract
The renin-angiotensin system (RAS) is involved in nociception and has functions in the cardiovascular system. The primary role of the RAS is to mediate the effect of angiotensin II (Ang II) through Ang II receptor type 2 (AT2). Due to this, AT2 has become a novel therapeutic target for the relief of peripheral neuropathic pain in humans. As it is one of the most popular induction agents of general anesthesia, propofol also exerts peripheral antinociceptive effects. The present study assessed the effect of propofol on the expression of AT2 in cultured dorsal root ganglion (DRG) neurons. The results indicate that propofol decreases AT2 mRNA expression in a statistically significant dose- and time-dependent manner (P<0.05). This resulted in a marked decrease in AT2 protein expression and the density of Ang II-binding AT2 on the cell membrane of DRG neurons. The effect of propofol was reversed by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. Although propofol exhibited no significant effect on AT2 gene promoter activity, it significantly decreased the stability of AT2 mRNA (P<0.05). However, this effect was reversed by LY294002. In addition, propofol increased PI3K activity in a concentration-dependent manner in DRG neurons. In conclusion, to the best of our knowledge, the current study provides the first evidence suggesting that propofol inhibits the expression of AT2 in DRG neurons by decreasing the stability of AT2 mRNA through a PI3K-dependent mechanism. The present study provides novel insights into the mechanisms of the peripheral antinociceptive action of propofol and suggests a potential means of regulating Ang II/AT2 signaling in the peripheral nervous system.
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Affiliation(s)
- Bingbing Pan
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan 410078, P.R. China
| | - Zhigang Cheng
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan 410078, P.R. China
| | - Gaoyin Kong
- Department of Anesthesiology, Hunan Provincial People's Hospital, Changsha, Hunan 410001, P.R. China
| | - Zongbin Song
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan 410078, P.R. China
| | - Yunjiao Wang
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan 410078, P.R. China
| | - Lai Wei
- Department of Anesthesiology, Hunan Provincial People's Hospital, Changsha, Hunan 410001, P.R. China
| | - Dan Xiao
- Department of Anesthesiology, Hunan Provincial People's Hospital, Changsha, Hunan 410001, P.R. China
| | - Yuan Zhao
- Department of Anesthesiology, Hunan Provincial People's Hospital, Changsha, Hunan 410001, P.R. China
| | - Qulian Guo
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan 410078, P.R. China
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20
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Breitinger U, Sticht H, Breitinger HG. Modulation of Recombinant Human α1 Glycine Receptors by Mono- and Disaccharides: A Kinetic Study. ACS Chem Neurosci 2016; 7:1077-87. [PMID: 27227552 DOI: 10.1021/acschemneuro.6b00044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Glycine receptors (GlyRs) mediate fast synaptic inhibition in spinal cord, brainstem, and higher brain centers. Recently, glucose was identified as a positive modulator of GlyR-mediated currents. Here, we investigated extent and kinetics of the positive modulation of recombinant human α1 glycine receptors by different mono- and disaccharides and sorbitol using patch-clamp recording techniques. Glucose and fructose augmented glycine-mediated whole-cell currents with an EC50 of 6-7 mM. At concentrations > 10 mM, the maximum of current enhancement was reached within ∼30 min. Kinetics of GlyR modulation resemble those of protein glycation. On-rates were <0.5 h for saturating concentrations of monosaccharides and ∼1.5 h for disaccharides. Off-rates were considerably slower (>24 h). Galactose, the C4-epimer of glucose, and the sugar alcohol sorbitol had no effect on GlyR currents. Recent cryoelectron microscopy structures were used to identify a potential binding site for saccharides near the ivermectin binding pocket with lysine 143 as possible attachment site. The GlyR mutant α1(K143A) was not potentiated by glucose, suggesting an involvement of this residue in glycine receptor modulation by saccharides.
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Affiliation(s)
- Ulrike Breitinger
- Department
of Biochemistry, The German University in Cairo, Main Entrance
of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Heinrich Sticht
- Bioinformatics, Institute for Biochemistry, Friedrich-Alexander-Universität Erlangen-Nümberg, Fahrstrasse 17, D-91054 Erlangen, Germany
| | - Hans-Georg Breitinger
- Department
of Biochemistry, The German University in Cairo, Main Entrance
of Al Tagamoa Al Khames, New Cairo 11835, Egypt
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21
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Veith VK, Quigley C, Treue S. A Pressure Injection System for Investigating the Neuropharmacology of Information Processing in Awake Behaving Macaque Monkey Cortex. J Vis Exp 2016:53724. [PMID: 27023110 PMCID: PMC4828981 DOI: 10.3791/53724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
The top-down modulation of feed-forward cortical information processing is functionally important for many cognitive processes, including the modulation of sensory information processing by attention. However, little is known about which neurotransmitter systems are involved in such modulations. A practical way to address this question is to combine single-cell recording with local and temporary neuropharmacological manipulation in a suitable animal model. Here we demonstrate a technique combining acute single-cell recordings with the injection of neuropharmacological agents in the direct vicinity of the recording electrode. The video shows the preparation of the pressure injection/recording system, including preparation of the substance to be injected. We show a rhesus monkey performing a visual attention task and the procedure of single-unit recording with block-wise pharmacological manipulations.
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Affiliation(s)
- Vera K Veith
- Cognitive Neuroscience Laboratory, German Primate Center;
| | | | - Stefan Treue
- Cognitive Neuroscience Laboratory, German Primate Center; Faculty of Biology and Psychology, Goettingen University
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22
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Spence A, Guerin G, Goeders N. Differential modulation of the discriminative stimulus effects of methamphetamine and cocaine by alprazolam and oxazepam in male and female rats. Neuropharmacology 2016; 102:146-57. [DOI: 10.1016/j.neuropharm.2015.10.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 10/10/2015] [Accepted: 10/29/2015] [Indexed: 11/17/2022]
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23
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Brodnik ZD, España RA. Dopamine uptake dynamics are preserved under isoflurane anesthesia. Neurosci Lett 2015; 606:129-34. [PMID: 26321152 DOI: 10.1016/j.neulet.2015.08.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 08/21/2015] [Accepted: 08/24/2015] [Indexed: 12/17/2022]
Abstract
Fast scan cyclic voltammetry is commonly used for measuring the kinetics of dopamine release and uptake. For experiments using an anesthetized preparation, urethane is preferentially used because it does not alter dopamine uptake kinetics compared to freely moving animals. Unfortunately, urethane is highly toxic, can induce premature death during experiments, and cannot be used for recovery surgeries. Isoflurane is an alternative anesthetic that is less toxic than urethane, produces a stable level of anesthesia over extended periods, and is often used for recovery surgeries. Despite these benefits, the effects of isoflurane on dopamine release and uptake have not been directly characterized. In the present studies, we assessed the utility of isoflurane for voltammetry experiments by testing dopamine signaling parameters under baseline conditions, after treatment with the dopamine uptake inhibitor cocaine, and after exposure to increasing concentrations of isoflurane. Our results indicate that surgical levels of isoflurane do not significantly alter terminal mechanisms of dopamine release and uptake over prolonged periods of time. Consequently, we propose that isoflurane is an acceptable anesthetic for voltammetry experiments, which in turn permits the design of studies in which dopamine signaling is examined under anesthesia prior to recovery and subsequent experimentation in the same animals.
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Affiliation(s)
- Zachary D Brodnik
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 W Queen Lane, Philadelphia, PA 19129, United States
| | - Rodrigo A España
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 W Queen Lane, Philadelphia, PA 19129, United States.
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24
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Repeated exposure to ketamine-xylazine during early development impairs motor learning-dependent dendritic spine plasticity in adulthood. Anesthesiology 2015; 122:821-31. [PMID: 25575163 DOI: 10.1097/aln.0000000000000579] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recent studies in rodents suggest that repeated and prolonged anesthetic exposure at early stages of development leads to cognitive and behavioral impairments later in life. However, the underlying mechanism remains unknown. In this study, we tested whether exposure to general anesthesia during early development will disrupt the maturation of synaptic circuits and compromise learning-related synaptic plasticity later in life. METHODS Mice received ketamine-xylazine (20/3 mg/kg) anesthesia for one or three times, starting at either early (postnatal day 14 [P14]) or late (P21) stages of development (n = 105). Control mice received saline injections (n = 34). At P30, mice were subjected to rotarod motor training and fear conditioning. Motor learning-induced synaptic remodeling was examined in vivo by repeatedly imaging fluorescently labeled postsynaptic dendritic spines in the primary motor cortex before and after training using two-photon microscopy. RESULTS Three exposures to ketamine-xylazine anesthesia between P14 and P18 impair the animals' motor learning and learning-dependent dendritic spine plasticity (new spine formation, 8.4 ± 1.3% [mean ± SD] vs. 13.4 ± 1.8%, P = 0.002) without affecting fear memory and cell apoptosis. One exposure at P14 or three exposures between P21 and P25 has no effects on the animals' motor learning or spine plasticity. Finally, enriched motor experience ameliorates anesthesia-induced motor learning impairment and synaptic deficits. CONCLUSIONS Our study demonstrates that repeated exposures to ketamine-xylazine during early development impair motor learning and learning-dependent dendritic spine plasticity later in life. The reduction in synaptic structural plasticity may underlie anesthesia-induced behavioral impairment.
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25
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Sieghart W. Allosteric modulation of GABAA receptors via multiple drug-binding sites. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 72:53-96. [PMID: 25600367 DOI: 10.1016/bs.apha.2014.10.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GABAA receptors are ligand-gated ion channels composed of five subunits that can be opened by GABA and be modulated by multiple pharmacologically and clinically important drugs. Over the time, hundreds of compounds from different structural classes have been demonstrated to modulate, directly activate, or inhibit GABAA receptors, and most of these compounds interact with more than one binding site at these receptors. Crystal structures of proteins and receptors homologous to GABAA receptors as well as homology modeling studies have provided insights into the possible location of ligand interaction sites. Some of these sites have been identified by mutagenesis, photolabeling, and docking studies. For most of these ligands, however, binding sites are not known. Due to the high flexibility of GABAA receptors and the existence of multiple drug-binding sites, the unequivocal identification of interaction sites for individual drugs is extremely difficult. The existence of multiple GABAA receptor subtypes with distinct subunit composition, the contribution of distinct subunit sequences to binding sites of different receptor subtypes, as well as the observation that even subunits not directly contributing to a binding site are able to influence affinity and efficacy of drugs, contribute to a unique pharmacology of each GABAA receptor subtype. Thus, each receptor subtype has to be investigated to identify a possible subtype selectivity of a compound. Although multiple binding sites make GABAA receptor pharmacology even more complicated, the exploitation of ligand interaction with novel-binding sites also offers additional possibilities for a subtype-selective modulation of GABAA receptors.
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Affiliation(s)
- Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain Research, Medical University Vienna, Vienna, Austria.
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26
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Herold KF, Sanford RL, Lee W, Schultz MF, Ingólfsson HI, Andersen OS, Hemmings HC. Volatile anesthetics inhibit sodium channels without altering bulk lipid bilayer properties. J Gen Physiol 2014; 144:545-60. [PMID: 25385786 PMCID: PMC4242807 DOI: 10.1085/jgp.201411172] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 10/08/2014] [Indexed: 01/05/2023] Open
Abstract
Although general anesthetics are clinically important and widely used, their molecular mechanisms of action remain poorly understood. Volatile anesthetics such as isoflurane (ISO) are thought to alter neuronal function by depressing excitatory and facilitating inhibitory neurotransmission through direct interactions with specific protein targets, including voltage-gated sodium channels (Na(v)). Many anesthetics alter lipid bilayer properties, suggesting that ion channel function might also be altered indirectly through effects on the lipid bilayer. We compared the effects of ISO and of a series of fluorobenzene (FB) model volatile anesthetics on Na(v) function and lipid bilayer properties. We examined the effects of these agents on Na(v) in neuronal cells using whole-cell electrophysiology, and on lipid bilayer properties using a gramicidin-based fluorescence assay, which is a functional assay for detecting changes in lipid bilayer properties sensed by a bilayer-spanning ion channel. At clinically relevant concentrations (defined by the minimum alveolar concentration), both the FBs and ISO produced prepulse-dependent inhibition of Na(v) and shifted the voltage dependence of inactivation toward more hyperpolarized potentials without affecting lipid bilayer properties, as sensed by gramicidin channels. Only at supra-anesthetic (toxic) concentrations did ISO alter lipid bilayer properties. These results suggest that clinically relevant concentrations of volatile anesthetics alter Na(v) function through direct interactions with the channel protein with little, if any, contribution from changes in bulk lipid bilayer properties. Our findings further suggest that changes in lipid bilayer properties are not involved in clinical anesthesia.
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Affiliation(s)
- Karl F Herold
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - R Lea Sanford
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - William Lee
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - Margaret F Schultz
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - Helgi I Ingólfsson
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - Olaf S Andersen
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
| | - Hugh C Hemmings
- Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065 Department of Anesthesiology, Department of Physiology and Biophysics, and Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065
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27
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Stuth EAE, Stucke AG, Zuperku EJ. Effects of anesthetics, sedatives, and opioids on ventilatory control. Compr Physiol 2013; 2:2281-367. [PMID: 23720250 DOI: 10.1002/cphy.c100061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.
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Affiliation(s)
- Eckehard A E Stuth
- Medical College of Wisconsin, Anesthesia Research Service, Zablocki VA Medical Center, Milwaukee, Wisconsin, USA.
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28
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Bhaskar SB, Bajwa SJS. Pharmaco-genomics and anaesthesia: Mysteries, correlations and facts. Indian J Anaesth 2013; 57:336-7. [PMID: 24163445 PMCID: PMC3800323 DOI: 10.4103/0019-5049.118517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- S Bala Bhaskar
- Department of Anaesthesiology and Critical Care, Vijayanagar Institute of Medical Sciences, Bellary, Karnataka, India
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29
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Borghese CM, Hicks JA, Lapid DJ, Trudell JR, Harris RA. GABA(A) receptor transmembrane amino acids are critical for alcohol action: disulfide cross-linking and alkyl methanethiosulfonate labeling reveal relative location of binding sites. J Neurochem 2013; 128:363-75. [PMID: 24117469 DOI: 10.1111/jnc.12476] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 09/26/2013] [Accepted: 09/30/2013] [Indexed: 11/27/2022]
Abstract
Alcohols and inhaled anesthetics modulate GABA(A) receptor (GABA(A)R) function via putative binding sites within the transmembrane regions. The relative position of the amino acids lining these sites could be either inter- or intra-subunit. We introduced cysteines in relevant TM locations and tested the proximity of cysteine pairs using oxidizing and reducing agents to induce or break disulfide bridges between cysteines, and thus change GABA-mediated currents in wild-type and mutant α1β2γ2 GABA(A)Rs expressed in Xenopus laevis oocytes. We tested for: (i) inter-subunit cross-linking: a cysteine located in α1TM1 [either α1(Q229C) or α1(L232C)] was paired with a cysteine in different positions of β2TM2 and TM3; (ii) intra-subunit cross-linking: a cysteine located either in β2TM1 [β2(T225C)] or in TM2 [β2(N265C)] was paired with a cysteine in different locations along β2TM3. Three inter-subunit cysteine pairs and four intra-subunits cross-linked. In three intra-subunit cysteine combinations, the alcohol effect was reduced by oxidizing agents, suggesting intra-subunit alcohol binding. We conclude that the structure of the alcohol binding site changes during activation and that potentiation or inhibition by binding at inter- or intra-subunit sites is determined by the specific receptor and ligand.
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Affiliation(s)
- Cecilia M Borghese
- Cellular and Molecular Biology, Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA
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30
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Mirheydari P, Ramerstorfer J, Varagic Z, Scholze P, Wimmer L, Mihovilovic MM, Sieghart W, Ernst M. Unexpected Properties of δ-Containing GABAA Receptors in Response to Ligands Interacting with the α+ β- Site. Neurochem Res 2013; 39:1057-1067. [PMID: 24072672 DOI: 10.1007/s11064-013-1156-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/11/2013] [Accepted: 09/17/2013] [Indexed: 10/26/2022]
Abstract
GABAA receptors are the major inhibitory neurotransmitter receptors in the central nervous system and are the targets of many clinically important drugs, which modulate GABA induced chloride flux by interacting with separate and distinct allosteric binding sites. Recently, we described an allosteric modulation occurring upon binding of pyrazoloquinolinones to a novel binding site at the extracellular α+ β- interface. Here, we investigated the effect of 4-(8-methoxy-3-oxo-3,5-dihydro-2H-pyrazolo[4,3-c]quinolin-2-yl)benzonitrile (the pyrazoloquinolinone LAU 177) at several αβ, αβγ and αβδ receptor subtypes. LAU 177 enhanced GABA-induced currents at all receptors investigated, and the extent of modulation depended on the type of α and β subunits present within the receptors. Whereas the presence of a γ2 subunit within αβγ2 receptors did not dramatically change LAU 177 induced modulation of GABA currents compared to αβ receptors, we observed an unexpected threefold increase in modulatory efficacy of this compound at α1β2,3δ receptors. Steric hindrance experiments as well as inhibition by the functional α+ β- site antagonist LAU 157 indicated that the effects of LAU 177 at all receptors investigated were mediated via the α+ β- interface. The stronger enhancement of GABA-induced currents by LAU 177 at α1β3δ receptors was not observed at α4,6β3δ receptors. Other experiments indicated that this enhancement of modulatory efficacy at α1β3δ receptors was not observed with another α+ β- modulator, and that the efficacy of modulation by α+ β- ligands is influenced by all subunits present in the receptor complex and by structural details of the respective ligand.
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Affiliation(s)
- Pantea Mirheydari
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Joachim Ramerstorfer
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Zdravko Varagic
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Laurin Wimmer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 6/163, 1060 Vienna, Austria
| | - Marko M Mihovilovic
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 6/163, 1060 Vienna, Austria
| | - Werner Sieghart
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Margot Ernst
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria.
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Piao MH, Liu Y, Wang YS, Qiu JP, Feng CS. Volatile anesthetic isoflurane inhibits LTP induction of hippocampal CA1 neurons through α4β2 nAChR subtype-mediated mechanisms. ACTA ACUST UNITED AC 2013; 32:e135-41. [PMID: 24011619 DOI: 10.1016/j.annfar.2013.05.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 05/21/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND PURPOSE Volatile anesthetic isoflurane contributes to postoperative cognitive dysfunction and inhibition of long-term potentiation (LTP), a synaptic model of learning and memory, but the mechanisms are uncertain. Central neuronal α4β2 subtype nicotinic acetylcholine receptors (nAChRs) are involved in the induction of LTP in the hippocampus. Isoflurane inhibits α4β2 nAChRs at concentrations lower than those used for anesthesia. Therefore, we hypothesized that isoflurane-inhibited LTP induction of hippocampal CA1 neurons via α4β2 nAChRs subtype inhibition. METHODS Transverse hippocampal slices (400μm thick) were obtained from male rats (6-8 weeks old). Population spikes were evoked using extracellular electrodes by electrical stimulation of the Schaffer collateral-commissural pathway of rat hippocampal slices. LTP was induced using high frequency stimulation (HFS; 100Hz, 1s). Clinically relevant concentrations (0.125-0.5mM) of isoflurane with or without nicotine (nAChRs agonist), mecamylamine (nAChRs antagonist), 3-[2(S)-2-azetidinylmethoxy] pyridine (A85380) and epibatidine (α4β2 nAChRs agonist), dihydro β erythroidine (DHβE) (α4β2 nAChRs antagonist) were added to the perfusion solution 20min before HFS to test their effects on LTP by HFS respectively. RESULTS A brief HFS induced stable LTP in rat hippocampal slices, but LTP was significantly inhibited in the presence of isoflurane at concentrations of 0.125-0.5mM. The inhibitive effect of isoflurane on LTP was not only reversible and could be prevented by nAChRs agonist nicotine and α4β2 nAChRs agonist A85380 and epibatidine, but also mimicked and potentiated by nAChRs antagonist mecamylamine and α4β2 nAChRs antagonist DHβE. CONCLUSIONS Inhibition of α4β2 nAChRs subtype of hippocampus participates in isoflurane-mediated LTP inhibition.
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Affiliation(s)
- M-H Piao
- Department of anesthesiology, the first hospital of Jilin university, n(o) 71, Xinmin St, 130021 Changchun, China; School of public health, Jilin university, Changchun 130021, China
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Shanmugasundararaj S, Das J, Sandberg WS, Zhou X, Wang D, Messing RO, Bruzik KS, Stehle T, Miller KW. Structural and functional characterization of an anesthetic binding site in the second cysteine-rich domain of protein kinase Cδ*. Biophys J 2013; 103:2331-40. [PMID: 23283232 DOI: 10.1016/j.bpj.2012.10.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 01/04/2023] Open
Abstract
Elucidating the principles governing anesthetic-protein interactions requires structural determinations at high resolutions not yet achieved with ion channels. Protein kinase C (PKC) activity is modulated by general anesthetics. We solved the structure of the phorbol-binding domain (C1B) of PKCδ complexed with an ether (methoxymethylcycloprane) and with an alcohol (cyclopropylmethanol) at 1.36-Å resolution. The cyclopropane rings of both agents displace a single water molecule in a surface pocket adjacent to the phorbol-binding site, making van der Waals contacts with the backbone and/or side chains of residues Asn-237 to Ser-240. Surprisingly, two water molecules anchored in a hydrogen-bonded chain between Thr-242 and Lys-260 impart elasticity to one side of the binding pocket. The cyclopropane ring takes part in π-acceptor hydrogen bonds with the amide of Met-239. There is a crucial hydrogen bond between the oxygen atoms of the anesthetics and the hydroxyl of Tyr-236. A Tyr-236-Phe mutation results in loss of binding. Thus, both van der Waals interactions and hydrogen-bonding are essential for binding to occur. Ethanol failed to bind because it is too short to benefit from both interactions. Cyclopropylmethanol inhibited phorbol-ester-induced PKCδ activity, but failed to do so in PKCδ containing the Tyr-236-Phe mutation.
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Takechi K, Carstens MI, Klein AH, Carstens E. The antinociceptive and antihyperalgesic effects of topical propofol on dorsal horn neurons in the rat. Anesth Analg 2013; 116:932-8. [PMID: 23337417 DOI: 10.1213/ane.0b013e31827f560d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Propofol (2,6-diisopropylphenol) is an IV anesthetic used for general anesthesia. Recent evidence suggests that propofol-anesthetized patients experience less postoperative pain, and that propofol has analgesic properties when applied topically. We presently investigated the antinociceptive effects of topical propofol using behavioral and single-unit electrophysiological methods in rats. METHODS In behavioral experiments with rats, we assessed the effect of topical hindpaw application of propofol (1%-25%) on heat and mechanically evoked paw withdrawals. In electrophysiological experiments, we recorded from lumbar dorsal horn wide dynamic range (WDR)-type neurons in pentobarbital-anesthetized rats. We assessed the effect of topical application of propofol to the ipsilateral hindpaw on neuronal responses elicited by noxious heat, cold, and mechanical stimuli. We additionally tested whether propofol blocks heat sensitization of paw withdrawals and WDR neuronal responses induced by topical application of allyl isothiocyanate (AITC; mustard oil). RESULTS Topical application of propofol (1%-25%) significantly increased the mean latency of the thermally evoked hindpaw withdrawal reflex on the treated (but not opposite) side in a concentration-dependent manner, with no effect on mechanically evoked hindpaw withdrawal thresholds. Propofol also prevented shortening of paw withdrawal latency induced by AITC. In electrophysiological experiments, topical application of 10% and 25% propofol, but not 1% propofol or vehicle (10% intralipid), to the ipsilateral hindpaw significantly attenuated the magnitude of responses of WDR neurons to noxious heating of glabrous hindpaw skin with no significant change in thermal thresholds. Maximal suppression of noxious heat-evoked responses was achieved 15 minutes after application followed by recovery to the pre-propofol baseline by 30 minutes. Responses to skin cooling or graded mechanical stimuli were not significantly affected by any concentration of propofol. Topical application of AITC enhanced the noxious heat-evoked response of dorsal horn neurons. This enhancement of heat-evoked responses was attenuated when 10% propofol was applied topically after application of AITC. CONCLUSIONS The results indicate that topical propofol inhibits responses of WDR neurons to noxious heat consistent with analgesia, and reduced AITC sensitization of WDR neurons consistent with an antihyperalgesic effect. These results are consistent with clinical studies demonstrating reduced postoperative pain in surgical patients anesthetized with propofol. The mechanism of analgesic action of topical propofol is not clear, but may involve desensitization of TRPV1 or TRPA1 receptors expressed in peripheral nociceptive nerve endings, engagement of endocannabinoids, or activation of peripheral γ-aminobutyric acid A receptors.
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Affiliation(s)
- Kenichi Takechi
- Department of Anesthesiology and Resuscitology, Ehime University Medical School, Matsuyama, Japan
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Petrenko AB, Yamakura T, Kohno T, Sakimura K, Baba H. Increased brain monoaminergic tone after the NMDA receptor GluN2A subunit gene knockout is responsible for resistance to the hypnotic effect of nitrous oxide. Eur J Pharmacol 2013; 698:200-5. [DOI: 10.1016/j.ejphar.2012.10.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 10/16/2012] [Accepted: 10/23/2012] [Indexed: 11/30/2022]
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Vanden Abeele F, Kondratskyi A, Dubois C, Shapovalov G, Gkika D, Busserolles J, Shuba Y, Skryma R, Prevarskaya N. Complex modulation of TRPM8 cold receptor by volatile anaesthetics and role in complications of general anaesthesia. J Cell Sci 2013; 126:4479-89. [DOI: 10.1242/jcs.131631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms by which volatile general anaesthetics (VAs) produce a depression of central nervous system are beginning to be better understood, but little is known about a number of side effects. Here, we show that the cold receptor, TRPM8, is complexly modulated by clinical concentration of VAs in dorsal root ganglion neurons and HEK-293 cells heterologously expressing TRPM8. VAs produced transient enhancement of TRPM8 via a depolarizing shift of its activation towards physiological membrane potentials, followed by a sustained TRPM8 inhibition. Stimulatory action of VAs engaged molecular determinants distinct from those used by the TRPM8 agonist. Transient TRPM8 activation by VAs could explain such side effects as inhibition of respiratory drive, shivering and cooling sensation during the beginning of anaesthesia, whereas the second phase of VA action associated with sustained TRPM8 inhibition may be responsible for hypothermia. Consistent with this, both hypothermia and inhibition of respiratory drive induced by VAs are partially abolished in TRPM8-null animals. Thus, we propose TRPM8 as a new clinical target for diminishing common and serious complications of general anaesthesia.
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Mutations M287L and Q266I in the glycine receptor α1 subunit change sensitivity to volatile anesthetics in oocytes and neurons, but not the minimal alveolar concentration in knockin mice. Anesthesiology 2012; 117:765-71. [PMID: 22885675 DOI: 10.1097/aln.0b013e31826a0d93] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Volatile anesthetics (VAs) alter the function of key central nervous system proteins but it is not clear which, if any, of these targets mediates the immobility produced by VAs in the face of noxious stimulation. A leading candidate is the glycine receptor, a ligand-gated ion channel important for spinal physiology. VAs variously enhance such function, and blockade of spinal glycine receptors with strychnine affects the minimal alveolar concentration (an anesthetic EC50) in proportion to the degree of enhancement. METHODS We produced single amino acid mutations into the glycine receptor α1 subunit that increased (M287L, third transmembrane region) or decreased (Q266I, second transmembrane region) sensitivity to isoflurane in recombinant receptors, and introduced such receptors into mice. The resulting knockin mice presented impaired glycinergic transmission, but heterozygous animals survived to adulthood, and we determined the effect of isoflurane on glycine-evoked responses of brainstem neurons from the knockin mice, and the minimal alveolar concentration for isoflurane and other VAs in the immature and mature knockin mice. RESULTS Studies of glycine-evoked currents in brainstem neurons from knockin mice confirmed the changes seen with recombinant receptors. No increases in the minimal alveolar concentration were found in knockin mice, but the minimal alveolar concentration for isoflurane and enflurane (but not halothane) decreased in 2-week-old Q266I mice. This change is opposite to the one expected for a mutation that decreases the sensitivity to volatile anesthetics. CONCLUSION Taken together, these results indicate that glycine receptors containing the α1 subunit are not likely to be crucial for the action of isoflurane and other VAs.
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Thiele A, Herrero JL, Distler C, Hoffmann KP. Contribution of cholinergic and GABAergic mechanisms to direction tuning, discriminability, response reliability, and neuronal rate correlations in macaque middle temporal area. J Neurosci 2012; 32:16602-15. [PMID: 23175816 PMCID: PMC6621794 DOI: 10.1523/jneurosci.0554-12.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 08/15/2012] [Accepted: 08/27/2012] [Indexed: 11/21/2022] Open
Abstract
Previous studies have investigated the effects of acetylcholine (ACh) on neuronal tuning, coding, and attention in primary visual cortex, but its contribution to coding in extrastriate cortex is unexplored. Here we investigate the effects of ACh on tuning properties of macaque middle temporal area MT neurons and contrast them with effects of gabazine, a GABA(A) receptor blocker. ACh increased neuronal activity, it had no effect on tuning width, but it significantly increased the direction discriminability of a neuron. Gabazine equally increased neuronal activity, but it widened tuning curves and decreased the direction discriminability of a neuron. Although gabazine significantly reduced response reliability, ACh application had little effect on response reliability. Finally, gabazine increased noise correlation of simultaneously recorded neurons, whereas ACh reduced it. Thus, both drugs increased firing rates, but only ACh application improved neuronal tuning and coding in line with effects seen in studies in which attention was selectively manipulated.
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Affiliation(s)
- Alexander Thiele
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
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Zimmermann I, Marabelli A, Bertozzi C, Sivilotti LG, Dutzler R. Inhibition of the prokaryotic pentameric ligand-gated ion channel ELIC by divalent cations. PLoS Biol 2012. [PMID: 23185134 PMCID: PMC3502511 DOI: 10.1371/journal.pbio.1001429] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The modulation of pentameric ligand-gated ion channels (pLGICs) by divalent cations is believed to play an important role in their regulation in a physiological context. Ions such as calcium or zinc influence the activity of pLGIC neurotransmitter receptors by binding to their extracellular domain and either potentiate or inhibit channel activation. Here we have investigated by electrophysiology and X-ray crystallography the effect of divalent ions on ELIC, a close prokaryotic pLGIC homologue of known structure. We found that divalent cations inhibit the activation of ELIC by the agonist cysteamine, reducing both its potency and, at higher concentrations, its maximum response. Crystal structures of the channel in complex with barium reveal the presence of several distinct binding sites. By mutagenesis we confirmed that the site responsible for divalent inhibition is located at the outer rim of the extracellular domain, at the interface between adjacent subunits but at some distance from the agonist binding region. Here, divalent cations interact with the protein via carboxylate side-chains, and the site is similar in structure to calcium binding sites described in other proteins. There is evidence that other pLGICs may be regulated by divalent ions binding to a similar region, even though the interacting residues are not conserved within the family. Our study provides structural and functional insight into the allosteric regulation of ELIC and is of potential relevance for the entire family.
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Affiliation(s)
- Iwan Zimmermann
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Alessandro Marabelli
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Carlo Bertozzi
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Lucia G. Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Raimund Dutzler
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
- * E-mail:
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Neurosteroids, stress and depression: potential therapeutic opportunities. Neurosci Biobehav Rev 2012; 37:109-22. [PMID: 23085210 DOI: 10.1016/j.neubiorev.2012.10.005] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/28/2012] [Accepted: 10/02/2012] [Indexed: 12/19/2022]
Abstract
Neurosteroids are potent and effective neuromodulators that are synthesized from cholesterol in the brain. These agents and their synthetic derivatives influence the function of multiple signaling pathways including receptors for γ-aminobutyric acid (GABA) and glutamate, the major inhibitory and excitatory neurotransmitters in the central nervous system (CNS). Increasing evidence indicates that dysregulation of neurosteroid production plays a role in the pathophysiology of stress and stress-related psychiatric disorders, including mood and anxiety disorders. In this paper, we review the mechanisms of neurosteroid action in brain with an emphasis on those neurosteroids that potently modulate the function of GABA(A) receptors. We then discuss evidence indicating a role for GABA and neurosteroids in stress and depression, and focus on potential strategies that can be used to manipulate CNS neurosteroid synthesis and function for therapeutic purposes.
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Sieghart W, Ramerstorfer J, Sarto-Jackson I, Varagic Z, Ernst M. A novel GABA(A) receptor pharmacology: drugs interacting with the α(+) β(-) interface. Br J Pharmacol 2012; 166:476-85. [PMID: 22074382 DOI: 10.1111/j.1476-5381.2011.01779.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
GABA(A) receptors are ligand-gated chloride channels composed of five subunits that can belong to different subunit classes. The existence of 19 different subunits gives rise to a multiplicity of GABA(A) receptor subtypes with distinct subunit composition; regional, cellular and subcellular distribution; and pharmacology. Most of these receptors are composed of two α, two β and one γ2 subunits. GABA(A) receptors are the site of action of a variety of pharmacologically and clinically important drugs, such as benzodiazepines, barbiturates, neuroactive steroids, anaesthetics and convulsants. Whereas GABA acts at the two extracellular β(+) α(-) interfaces of GABA(A) receptors, the allosteric modulatory benzodiazepines interact with the extracellular α(+) γ2(-) interface. In contrast, barbiturates, neuroactive steroids and anaesthetics seem to interact with solvent accessible pockets in the transmembrane domain. Several benzodiazepine site ligands have been identified that selectively interact with GABA(A) receptor subtypes containing α2βγ2, α3βγ2 or α5βγ2 subunits. This indicates that the different α subunit types present in these receptors convey sufficient structural differences to the benzodiazepine binding site to allow specific interaction with certain benzodiazepine site ligands. Recently, a novel drug binding site was identified at the α(+) β(-) interface. This binding site is homologous to the benzodiazepine binding site at the α(+) γ2(-) interface and is thus also strongly influenced by the type of α subunit present in the receptor. Drugs interacting with this binding site cannot directly activate but only allosterically modulate GABA(A) receptors. The possible importance of such drugs addressing a spectrum of receptor subtypes completely different from that of benzodiazepines is discussed.
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Affiliation(s)
- Werner Sieghart
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Vienna, Austria
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Cederholm JME, Froud KE, Wong ACY, Ko M, Ryan AF, Housley GD. Differential actions of isoflurane and ketamine-based anaesthetics on cochlear function in the mouse. Hear Res 2012; 292:71-9. [PMID: 22960466 DOI: 10.1016/j.heares.2012.08.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/13/2012] [Accepted: 08/21/2012] [Indexed: 10/28/2022]
Abstract
Isoflurane is a volatile inhaled anaesthetic widely used in animal research, with particular utility for hearing research. Isoflurane has been shown to blunt hearing sensitivity compared with the awake state, but little is known about how isoflurane compares with other anaesthetics with regard to hair cell transduction and auditory neurotransmission. The current study was undertaken in C57Bl/6J and C129/SvEv strains of mice to determine whether isoflurane anaesthesia affects hearing function relative to ketamine-based anaesthesia. Cochlear function and central auditory transmission were assessed using auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE), comparing thresholds and input/output functions over time, for isoflurane vs. ketamine/xylazine/acepromazine anaesthesia. ABR thresholds at the most sensitive region of hearing (16 kHz) were initially higher under isoflurane anaesthesia. This reduced hearing sensitivity worsened over the 1 h study period, and also became evident with broadband click stimulus. Ketamine anaesthesia provided stable ABR thresholds. Although the growth functions were unchanged over time for both anaesthetics, the slopes under isoflurane anaesthesia were significantly less. Cubic (2f(1)-f(2)) DPOAE thresholds and growth functions were initially similar for both anaesthetics. After 60 min, DPOAE thresholds increased for both groups, but this effect was significantly greater with ketamine anaesthesia. The isoflurane-mediated increase in ABR thresholds over time is attributable to action on cochlear nerve activation, evident as a right-shift in the P1-N1 input/output function compared to K/X/A. The ketamine-based anaesthetic produced stable ABR thresholds and gain over time, despite a right-shift in the outer hair cell - mediated DPOAE input/output function.
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Affiliation(s)
- Jennie M E Cederholm
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, UNSW Kensington Campus, Sydney, NSW Australia
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Schaper C, Höcker J, Böhm R, Roeder T, Bein B. The shaker potassium channel is no target for xenon anesthesia in short-sleeping Drosophila melanogaster mutants. ScientificWorldJournal 2012; 2012:373709. [PMID: 22761550 PMCID: PMC3385613 DOI: 10.1100/2012/373709] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 04/27/2012] [Indexed: 11/17/2022] Open
Abstract
Background. Xenon seems to be an ideal anesthetic drug. To explore if next to the antagonism at the NMDA-receptor other molecular targets are involved, we tested the xenon requirement in short sleeping Drosophila shaker mutants and in na[har38]. Methods. The Drosophila melanogaster strains wildtype Canton-S, na[har38], sh102 and shmns, were raised and sleep was measured. Based on the response of the flies at different xenon concentrations, logEC50 values were calculated. Results. The logEC50-values for WT Canton-S were 1.671 (1.601–1.742 95%-confidence intervall; n = 238; P versus sh102 > 0,05), for shmns 1.711 (1.650–1.773; n = 242; P versus WT Canton-S > 0,05). The logEC50-value for sh102 was 1.594 (1.493–1.694; n = 261; P versus shmns > 0.05). The logEC-value of na[har38] was 2.076 (1.619–2.532; n = 207; P versus shmns < 0.05, versus sh102 < 0.05, versus WT Canton-S < 0.05). P values for all shaker mutants were P > 0.05, while na[har38] was found to be hyposensitive compared to wildtype (P < 0.05). Conclusions. The xenon requirement in Drosophila melanogaster is not influenced by a single gene mutation at the shaker locus, whereas a reduced expression of a nonselective cation channel leads to an increased xenon requirement. This supports the thesis that xenon mediates its effects not only via an antagonism at the NMDA-receptor.
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Affiliation(s)
- C Schaper
- Department of Anaesthesiology and Operrative Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Germany.
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General anesthetics predicted to block the GLIC pore with micromolar affinity. PLoS Comput Biol 2012; 8:e1002532. [PMID: 22693438 PMCID: PMC3364936 DOI: 10.1371/journal.pcbi.1002532] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 04/02/2012] [Indexed: 01/23/2023] Open
Abstract
Although general anesthetics are known to modulate the activity of ligand-gated ion channels in the Cys-loop superfamily, there is at present neither consensus on the underlying mechanisms, nor predictive models of this modulation. Viable models need to offer quantitative assessment of the relative importance of several identified anesthetic binding sites. However, to date, precise affinity data for individual sites has been challenging to obtain by biophysical means. Here, the likely role of pore block inhibition by the general anesthetics isoflurane and propofol of the prokaryotic pentameric channel GLIC is investigated by molecular simulations. Microscopic affinities are calculated for both single and double occupancy binding of isoflurane and propofol to the GLIC pore. Computations are carried out for an open-pore conformation in which the pore is restrained to crystallographic radius, and a closed-pore conformation that results from unrestrained molecular dynamics equilibration of the structure. The GLIC pore is predicted to be blocked at the micromolar concentrations for which inhibition by isofluorane and propofol is observed experimentally. Calculated affinities suggest that pore block by propofol occurs at signifcantly lower concentrations than those for which inhibition is observed: we argue that this discrepancy may result from binding of propofol to an allosteric site recently identified by X-ray crystallography, which may cause a competing gain-of-function effect. Affinities of isoflurane and propofol to the allosteric site are also calculated, and shown to be 3 mM for isoflurane and for propofol; both anesthetics have a lower affinity for the allosteric site than for the unoccupied pore. Although general anesthesia is performed every day on thousands of people, its detailed microscopic mechanisms are not known. What is known is that general anesthetic drugs modulate the activity of ion channels in the central nervous system. These channels are proteins that open in response to binding of neurotransmitter molecules, creating an electric current through the cell membrane and thus propagating nerve impulses between cells. One possible mechanism for ion channel inhibition by anesthetics is that the drugs bind inside the pore of the channels, blocking ion current. Here we investigate such a pore block mechanism by computing the strength of the drugs' interaction with the pore – and hence the likelihood of binding, in the case of GLIC, a bacterial channel protein. The results, obtained from numerical simulations of atomic models of GLIC, indicate that the anesthetics isoflurane and propofol have a tendency to bind in the pore that is strong enough to explain blocking of the channel, even at low concentration of the drugs.
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Abstract
Inhibitory (or strychnine sensitive) glycine receptors (GlyRs) are anion-selective transmitter-gated ion channels of the cys-loop superfamily, which includes among others also the inhibitory γ-aminobutyric acid receptors (GABA(A) receptors). While GABA mediates fast inhibitory neurotransmission throughout the CNS, the action of glycine as a fast inhibitory neurotransmitter is more restricted. This probably explains why GABA(A) receptors constitute a group of extremely successful drug targets in the treatment of a wide variety of CNS diseases, including anxiety, sleep disorders and epilepsy, while drugs specifically targeting GlyRs are virtually lacking. However, the spatially more restricted distribution of glycinergic inhibition may be advantageous in situations when a more localized enhancement of inhibition is sought. Inhibitory GlyRs are particularly relevant for the control of excitability in the mammalian spinal cord, brain stem and a few selected brain areas, such as the cerebellum and the retina. At these sites, GlyRs regulate important physiological functions, including respiratory rhythms, motor control, muscle tone and sensory as well as pain processing. In the hippocampus, RNA-edited high affinity extrasynaptic GlyRs may contribute to the pathology of temporal lobe epilepsy. Although specific modulators have not yet been identified, GlyRs still possess sites for allosteric modulation by a number of structurally diverse molecules, including alcohols, neurosteroids, cannabinoids, tropeines, general anaesthetics, certain neurotransmitters and cations. This review summarizes the present knowledge about this modulation and the molecular bases of the interactions involved.
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Affiliation(s)
- Gonzalo E Yevenes
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
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Abstract
Millions of human infants receive general anesthetics for surgery or diagnostic procedures every year worldwide, and there is a growing inquietude regarding the safety of these drugs for the developing brain. In fact, accumulating experimental evidence together with recent epidemiologic observations suggest that general anesthetics might exert undesirable effects on the immature nervous system. The goal of this review is to highlight basic science issues as well as to critically present experimental data and clinical observations relevant to this possibility. By acting on a plethora of ligand-gated ion channels, general anesthetics are powerful modulators of neural activity. Since even brief interference with physiologic activity patterns during critical periods of development are known to induce permanent alterations in brain circuitry, anesthetic-induced interference with brain development is highly plausible. In line with this hypothesis, compelling experimental evidence, from rodents to primates, suggests increased neuroapoptosis and associated long-term neurocognitive deficits following administration of these drugs at defined stages of development. Recent epidemiologic studies also indicate a potential association between anesthesia/surgery and subsequently impaired neurocognitive function in humans. It is, however, important to note that extrapolation of experimental studies to human practice requires extreme caution, and that currently available human data are hindered by a large number of potentially confounding factors. Thus, despite significant advances in the field, there is still insufficient evidence to determine whether anesthetics are harmful to the developing human brain. Consequently, no change in clinical practice can be recommended.
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Affiliation(s)
- Laszlo Vutskits
- Pediatric Anesthesia Unit, Department of Anesthesiology, Pharmacology and Intensive Care, University Hospital of Geneva, Geneva, Switzerland.
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Abstract
This opening chapter recalls the history of the discoveries that led to the appreciation of the nature and importance of molecular chirality in biology, as well as the development of stereochemistry as an interdisciplinary field connecting chemistry and biology. The discoveries described cover roughly the period of ca. 1840-1940, although certain relevant events of earlier or later times are also addressed. A large number of chiral substances occur in nature in unichiral (i.e., single-enantiomer) form, and for centuries many such substances were used in crude extracts for relief from diseases. For the science of biochirality, the first milestone was the discovery of molecular chirality by Louis Pasteur in 1848. Thereafter, fundamental advances were made, beginning in 1857 with Pasteur's discovery of biological enantioselectivity, in the metabolism of (±)-tartaric acid. With the advances in organic chemistry during the second half of the nineteenth century, the structures of many organic molecules were elucidated and new chiral compounds synthesized, and by the turn of the twentieth century studies of stereoselectivity in the biological activity or enzymatic transformations of natural or synthetic substances were proliferating, and chiroselectivity was often found. Among the names associated with important discoveries in biochirality appear Pasteur, Piutti, Fischer, Cushny, Easson and Stedman, and others. The findings soon prompted attempts to explain the phenomenon of enantioselectivity in biological action, beginning with Pasteur's proposal to account for enantioselectivity in the metabolism of tartaric acid. In 1894 Fischer announced his "lock-and-key" metaphor to explain enantioselectivity in enzyme-substrate interactions and in 1933 Easson and Stedman advanced the first chemical-structure-based model, the three-point-attachment paradigm, to rationalize enantioselectivity at adrenergic receptors. This model has been generalized as the simplest basis for enantioselectivity in biological activity. Today molecular chirality is widely recognized as an important modulator of the effects of chiral substances in a variety of branches of biology and medicine.
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Transient effects of anesthetics on dendritic spines and filopodia in the living mouse cortex. Anesthesiology 2011; 115:718-26. [PMID: 21768874 DOI: 10.1097/aln.0b013e318229a660] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Anesthetics are widely used to induce unconsciousness, pain relief, and immobility during surgery. It remains unclear whether the use of anesthetics has significant and long-lasting effects on synapse development and plasticity in the brain. To address this question, the authors examined the formation and elimination of dendritic spines, postsynaptic sites of excitatory synapses, in the developing mouse cortex during and after anesthetics exposure. METHODS Transgenic mice expressing yellow fluorescence protein in layer 5 pyramidal neurons were used in this study. Mice at 1 month of age underwent ketamine-xylazine and isoflurane anesthesia over a period of hours. The elimination and formation rates of dendritic spines and filopodia, the precursors of spines, were followed over hours to days in the primary somatosensory cortex using transcranial two-photon microscopy. Four to five animals were examined under each experimental condition. Student t test and Mann-Whitney U test were used to analyze the data. RESULTS Administration of either ketamine-xylazine or isoflurane rapidly altered dendritic filopodial dynamics but had no significant effects on spine dynamics. Ketamine-xylazine increased filopodial formation whereas isoflurane decreased filopodial elimination during 4 h of anesthesia. Both effects were transient and disappeared within a day after the animals woke up. CONCLUSION Studies suggest that exposure to anesthetics transiently affects the dynamics of dendritic filopodia but has no significant effect on dendritic spine development and plasticity in the cortex of 1-month-old mice.
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Müller CP, Pum ME, Amato D, Schüttler J, Huston JP, De Souza Silva MA. The in vivo neurochemistry of the brain during general anesthesia. J Neurochem 2011; 119:419-46. [DOI: 10.1111/j.1471-4159.2011.07445.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Teppema LJ, Baby S. Anesthetics and control of breathing. Respir Physiol Neurobiol 2011; 177:80-92. [PMID: 21514403 DOI: 10.1016/j.resp.2011.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 12/18/2022]
Abstract
An important side effect of general anesthetics is respiratory depression. Anesthetics have multiple membrane targets of which ionotropic receptors such as gamma-aminobutyric acid-A (GABA(A)), glycine, N-methyl-D-aspartate and nicotinic acetylcholinergic (nACh) receptors are important members. GABA, glutamate and ACh are crucial neurotransmitters in the respiratory neuronal network, and the ability of anesthetics to modulate their release and interact with their receptors implies complex effects on respiration. Metabotropic receptors and intracellular proteins are other important targets for anesthetics suggesting complex effects on intracellular signaling pathways. Here we briefly overview the effects of general anesthetics on protein targets as far as these are relevant for respiratory control. Subsequently, we describe some methods with which the overall effect of anesthetics on the control of breathing can be measured, as well as some promising in vivo approaches to study their synaptic effects. Finally, we summarize the most important respiratory effects of volatile anesthetics in humans and animals and those of some intravenous anesthetics in animals.
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Affiliation(s)
- Luc J Teppema
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands.
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Mechanisms of general anesthetic action: Focus on the cellular network. Transl Neurosci 2011. [DOI: 10.2478/s13380-011-0022-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe discovery of general anesthetics had a tremendous impact on development of surgery and medicine in general, during the last century. Despite the widespread use of general anesthetics, the mechanisms by which they produce their effects in the central nervous system are still poorly understood. Over the past decade, several new findings have contributed significantly to a better understanding of general anesthetic mechanisms. The current review summarizes recent data on different anesthetic neuronal targets that might be involved in the mechanism of action of general anesthetics, giving special attention to the importance of binding pockets for anesthetics within transmembrane receptors and cellular signaling leading to morphological changes of neuronal cells. Several lines of evidence suggest that disruption in brain network connectivity is important for anaesthesia-induced loss of consciousness and this is discussed in relation to morphological changes.
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