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Crowder CM, Forman SA. Systematized Serendipity: Fishing Expeditions for Anesthetic Drugs and Targets. Anesthesiology 2024:141931. [PMID: 39240535 DOI: 10.1097/aln.0000000000005153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2024]
Abstract
Most of science involves making observations, forming hypotheses, and testing those hypotheses, to form valid conclusions. However, a distinct, longstanding, and very productive scientific approach does not follow this paradigm; rather, it begins with a screen through a random collection of drugs or genetic variations for a particular effect or phenotype. Subsequently, the identity of the drug or gene is determined, and only then are hypotheses formed and the more standard scientific method employed. This alternative approach is called forward screening and includes methods such as genetic mutant screens, small molecule screens, metabolomics, proteomics, and transcriptomics. This review explains the rational for forward screening approaches and uses examples of screens for mutants with altered anesthetic sensitivities and for novel anesthetics to illustrate the methods and impact of the approach. Forward screening approaches are becoming even more powerful with advances in bioinformatics aided by artificial intelligence.
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Affiliation(s)
- C Michael Crowder
- Department of Anesthesiology and Pain Medicine, Department of Genome Sciences, Mitochondrial and Metabolism Center, University of Washington, Seattle, Washington
| | - Stuart A Forman
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts; Harvard Medical School, Boston Massachusetts
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2
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Plasencia DM, Rodgers LH, Knighton AR, Eckenhoff RG, White ER. Antagonism of propofol anesthesia by alkyl-fluorobenzene derivatives. Sci Rep 2024; 14:15943. [PMID: 38987614 PMCID: PMC11236999 DOI: 10.1038/s41598-024-66672-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 07/03/2024] [Indexed: 07/12/2024] Open
Abstract
Despite their frequent use across many clinical settings, general anesthetics are medications with lethal side effects and no reversal agents. A fluorinated analogue of propofol has previously been shown to antagonize propofol anesthesia in tadpoles and zebrafish, but little further investigation of this class of molecules as anesthetic antagonists has been conducted. A 13-member library of alkyl-fluorobenzene derivatives was tested in an established behavioral model of anesthesia in zebrafish at 5 days post fertilization. These compounds were examined for their ability to antagonize propofol and two volatile anesthetics, as well as their interaction with the anesthetic-binding model protein apoferritin. Two compounds provided significant antagonism of propofol, and when combined, were synergistic, suggesting more than one antagonist sensitive target site. These compounds did not antagonize the volatile anesthetics, indicating some selectivity amongst general anesthetics. For the compounds with the most antagonistic potency, similarities in structure and binding to apoferritin may be suggestive of competitive antagonism; however, this was not supported by a Schild analysis. This is consistent with multiple targets contributing to general anesthesia, but whether these are physiologic antagonists or are antagonists at only some subset of the many anesthetic potential targets remains unclear, and will require additional investigation.
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Affiliation(s)
- Diana M Plasencia
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Liam H Rodgers
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Alexys R Knighton
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - E Railey White
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
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3
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Li R, Zhang Y, Zhu Q, Wu Y, Song W. The role of anesthesia in peri‑operative neurocognitive disorders: Molecular mechanisms and preventive strategies. FUNDAMENTAL RESEARCH 2024; 4:797-805. [PMID: 39161414 PMCID: PMC11331737 DOI: 10.1016/j.fmre.2023.02.007] [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: 10/11/2022] [Revised: 12/21/2022] [Accepted: 02/15/2023] [Indexed: 03/18/2023] Open
Abstract
Peri-operative neurocognitive disorders (PNDs) include postoperative delirium (POD) and postoperative cognitive dysfunction (POCD). Children and the elderly are the two populations most vulnerable to the development of POD and POCD, which results in both high morbidity and mortality. There are many factors, including neuroinflammation and oxidative stress, that are associated with POD and POCD. General anesthesia is a major risk factor of PNDs. However, the molecular mechanisms of PNDs are poorly understood. Dexmedetomidine (DEX) is a useful sedative agent with analgesic properties, which significantly improves POCD in elderly patients. In this review, the current understanding of anesthesia in PNDs and the protective effects of DEX are summarized, and the underlying mechanisms are further discussed.
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Affiliation(s)
- Ran Li
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou 325035, China
| | - Yun Zhang
- The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Qinxin Zhu
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou 325035, China
| | - Yili Wu
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou 325035, China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou 325000, China
| | - Weihong Song
- The Second Affiliated Hospital and Yuying Children's Hospital, Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou 325035, China
- The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou 325000, China
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4
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Germann AL, Xu Y, Covey DF, Evers AS, Akk G. Comparison of Behavioral Effects of GABAergic Low- and High-Efficacy Neuroactive Steroids in the Zebrafish Larvae Assay. ACS Chem Neurosci 2024; 15:909-915. [PMID: 38386612 PMCID: PMC10953468 DOI: 10.1021/acschemneuro.3c00836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024] Open
Abstract
Activation of the GABAA receptor is associated with numerous behavioral end points ranging from anxiolysis to deep anesthesia. The specific behavioral effect of a GABAergic compound is considered to correlate with the degree of its functional effect on the receptor. Here, we tested the hypothesis that a low-efficacy allosteric potentiator of the GABAA receptor may act, due to a ceiling effect, as a sedative with reduced and limited action. We synthesized a derivative, named (3α,5β)-20-methyl-pregnane-3,20-diol (KK-235), of the GABAergic neurosteroid 5β-pregnane-3α,20α-diol. Using electrophysiology, we showed that KK-235 is a low-efficacy potentiator of the synaptic-type α1β2γ2L GABAA receptor. In the zebrafish larvae behavioral assay, KK-235 was found to only partially block the inverted photomotor response (PMR) and to weakly reduce swimming behavior, whereas the high-efficacy GABAergic steroid (3α,5α,17β)-3-hydroxyandrostane-17-carbonitrile (ACN) fully blocked PMR and spontaneous swimming. Coapplication of KK-235 reduced the potentiating effect of ACN in an electrophysiological assay and dampened its sedative effect in behavioral experiments. We propose that low-efficacy GABAergic potentiators may be useful as sedatives with limited action.
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Affiliation(s)
- Allison L. Germann
- Departments of Anesthesiology (ALG, ASE, GA) and Developmental Biology (YX, DFC), and the Taylor Family Institute for Innovative Psychiatric Research (DFC, ASE, GA), Washington University School of Medicine, St Louis, MO 63110, USA
| | - Yuanjian Xu
- Departments of Anesthesiology (ALG, ASE, GA) and Developmental Biology (YX, DFC), and the Taylor Family Institute for Innovative Psychiatric Research (DFC, ASE, GA), Washington University School of Medicine, St Louis, MO 63110, USA
| | - Douglas F. Covey
- Departments of Anesthesiology (ALG, ASE, GA) and Developmental Biology (YX, DFC), and the Taylor Family Institute for Innovative Psychiatric Research (DFC, ASE, GA), Washington University School of Medicine, St Louis, MO 63110, USA
| | - Alex S. Evers
- Departments of Anesthesiology (ALG, ASE, GA) and Developmental Biology (YX, DFC), and the Taylor Family Institute for Innovative Psychiatric Research (DFC, ASE, GA), Washington University School of Medicine, St Louis, MO 63110, USA
| | - Gustav Akk
- Departments of Anesthesiology (ALG, ASE, GA) and Developmental Biology (YX, DFC), and the Taylor Family Institute for Innovative Psychiatric Research (DFC, ASE, GA), Washington University School of Medicine, St Louis, MO 63110, USA
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5
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Plasencia DM, Rodgers LH, Knighton AR, Eckenhoff RG, White ER. Antagonism of Propofol Anesthesia by Alkyl-fluorobenzene Derivatives. RESEARCH SQUARE 2024:rs.3.rs-3846123. [PMID: 38260679 PMCID: PMC10802710 DOI: 10.21203/rs.3.rs-3846123/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Despite their frequent use across many clinical settings, general anesthetics are medications with lethal side effects and no reversal agents. A fluorinated analogue of propofol has previously been shown to antagonize propofol anesthesia in tadpoles and zebrafish, but little further investigation of this class of molecules as anesthetic antagonists has been conducted. A 13-member library of alkyl-fluorobenzene derivatives was tested in an established behavioral model of anesthesia in zebrafish at 5 days post fertilization. These compounds were examined for their ability to antagonize propofol and two volatile anesthetics, as well as their binding to the anesthetic-binding model protein apoferritin. The two compounds demonstrating highest antagonistic potency were found to bind apoferritin in a manner similar to propofol. Selected compounds did not show antagonism of volatile anesthetics, indicating some selectivity of this antagonism. Similarities in structure and binding to apoferritin as well as a Schild analysis are suggestive of competitive antagonism, but like the anesthetics, the potential mechanism(s) of these antagonists will require further mechanistic investigation.
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Affiliation(s)
- Diana M. Plasencia
- Department of Anesthesiology & Critical Care, University of Pennsylvania, Perelman School of Medicine, Philadelphia, United States of America
| | - Liam H. Rodgers
- Department of Anesthesiology & Critical Care, University of Pennsylvania, Perelman School of Medicine, Philadelphia, United States of America
| | - Alexys R. Knighton
- Department of Anesthesiology & Critical Care, University of Pennsylvania, Perelman School of Medicine, Philadelphia, United States of America
| | - Roderic G. Eckenhoff
- Department of Anesthesiology & Critical Care, University of Pennsylvania, Perelman School of Medicine, Philadelphia, United States of America
| | - E. Railey White
- Department of Anesthesiology & Critical Care, University of Pennsylvania, Perelman School of Medicine, Philadelphia, United States of America
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Bhave K, Forman SA. Substituted Cysteine Modification and Protection with n-Alkyl-MTS Reagents Quantifies Steric Changes Induced by a Mutation in Anesthetic Binding Sites on GABA Type A Receptors. Mol Pharmacol 2023; 104:266-274. [PMID: 37586749 PMCID: PMC10658906 DOI: 10.1124/molpharm.123.000719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 08/18/2023] Open
Abstract
Multiple approaches, including cryogenic electron microscopy (cryo-EM), indicate that the anesthetics etomidate and propofol modulate α1β2/3γ2 GABAA receptors by binding in overlapping transmembrane inter-subunit sites near βM286 and αL232 sidechains. High-precision approaches in functional receptors are needed for comparisons with cryo-EM. We previously used substituted cysteine modification and protection (SCAMP) with n-alkyl-methanethiosulfonate (MTS) reagents and electrophysiology in α1β3M286Cγ2L receptors to estimate the distance from etomidate to β3M286 with precision near 1.3 Å. Here, we address three more aims using this approach: (i) SCAMP with etomidate was tested in α1L232Cβ3γ2L receptors; (ii) studies in α1L232Wβ3M286Cγ2L receptors assessed whether α1L232W displaces etomidate relative to β3M286C; and (iii) results with propofol were compared with those with etomidate. Voltage-clamp electrophysiology in Xenopus oocytes was used to assess persistent functional changes after exposing cysteine-substituted receptors to methyl-MTS through n-decyl-MTS. Overlap of modified cysteine sidechains with bound anesthetic was inferred when anesthetic co-application with alkyl-MTS reagent blocked the development of persistent effects. In α1L232Cβ3γ2L receptors, only pentyl-MTS and hexyl-MTS induced persistent effects that were unaltered by etomidate co-application, precluding a direct estimate of intermolecular distance. In α1L232Wβ3M286Cγ2L receptors, sidechain overlap with bound etomidate was inferred for modifications with ethyl-MTS through n-pentyl-MTS, with unambiguous cut-on and cut-off. Comparison with results in α1β3M286Cγ2L reveals that α1L232W, which increases maximal sidechain length by 2.1 Å, displaces etomidate closer to β3M286C by about 1.3 Å. Propofol results largely mirrored those with etomidate. These findings indicate that both etomidate and propofol bind within 1 Å of α1L232, consistent with cryo-EM structures. SIGNIFICANCE STATEMENT: We combined electrophysiology, cysteine substitutions, and n-alkyl-methanethiosulfonate modifiers in functional GABAA receptors to enable precise estimates of the distance between β3M286C sidechains and anesthetics (etomidate and propofol) bound in transmembrane β+/α- inter-subunit pockets. Comparing results in α1β3M286Cγ2L and α1L232Wβ3M286Cγ2L receptors reveals that α1L232W mutations displace both anesthetics toward β3M286C, indicating that these anesthetics bind within 1 Å of the α1L232 sidechain in functional receptors, consistent with cryogenic electron microscopy structures derived under nonphysiologic conditions.
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Affiliation(s)
- Kieran Bhave
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Stuart A Forman
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
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Hoyt H, Fantasia RJ, Bhave K, Yang X, Forman SA. Photomotor Responses in Zebrafish and Electrophysiology Reveal Varying Interactions of Anesthetics Targeting Distinct Sites on γ-Aminobutyric Acid Type A Receptors. Anesthesiology 2022; 137:568-585. [PMID: 36018576 PMCID: PMC9588801 DOI: 10.1097/aln.0000000000004361] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Etomidate, barbiturates, alfaxalone, and propofol are anesthetics that allosterically modulate γ-aminobutyric acid type A (GABAA) receptors via distinct sets of molecular binding sites. Two-state concerted coagonist models account for anesthetic effects and predict supra-additive interactions between drug pairs acting at distinct sites. Some behavioral and molecular studies support these predictions, while other findings suggest potentially complex anesthetic interactions. We therefore evaluated interactions among four anesthetics in both animals and GABAA receptors. METHODS The authors used video assessment of photomotor responses in zebrafish larvae and isobolography to evaluate hypnotic drug pair interactions. Voltage clamp electrophysiology and allosteric shift analysis evaluated coagonist interactions in α1β3γ2L receptors activated by γ-aminobutyric acid (GABA) versus anesthetics [log(d, AN):log(d, GABA) ratio]. Anesthetic interactions at concentrations relevant to zebrafish were assessed in receptors activated with low GABA. RESULTS In zebrafish larvae, etomidate interacted additively with both propofol and the barbiturate R-5-allyl-1-methyl m-trifluoromethyl mephobarbital (R-mTFD-MPAB; mean ± SD α = 1.0 ± 0.07 and 0.96 ± 0.11 respectively, where 1.0 indicates additivity), while the four other drug pairs displayed synergy (mean α range 0.76 to 0.89). Electrophysiologic allosteric shifts revealed that both propofol and R-mTFD-MPAB modulated etomidate-activated receptors much less than GABA-activated receptors [log(d, AN):log(d, GABA) ratios = 0.09 ± 0.021 and 0.38 ± 0.024, respectively], while alfaxalone comparably modulated receptors activated by GABA or etomidate [log(d) ratio = 0.87 ± 0.056]. With low GABA activation, etomidate combined with alfaxalone was supra-additive (n = 6; P = 0.023 by paired t test), but etomidate plus R-mTFD-MPAB or propofol was not. CONCLUSIONS In both zebrafish and GABAA receptors, anesthetic drug pairs interacted variably, ranging from additivity to synergy. Pairs including etomidate displayed corresponding interactions in animals and receptors. Some of these results challenge simple two-state coagonist models and support alternatives where different anesthetics may stabilize distinct receptor conformations, altering the effects of other drugs. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Helen Hoyt
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Ryan J Fantasia
- School of Biologic Sciences, University of California-San Diego, San Diego, California
| | - Kieran Bhave
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Xiaoxuan Yang
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Stuart A Forman
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
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Ochenkowska K, Herold A, Samarut É. Zebrafish Is a Powerful Tool for Precision Medicine Approaches to Neurological Disorders. Front Mol Neurosci 2022; 15:944693. [PMID: 35875659 PMCID: PMC9298522 DOI: 10.3389/fnmol.2022.944693] [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: 05/15/2022] [Accepted: 06/17/2022] [Indexed: 12/17/2022] Open
Abstract
Personalized medicine is currently one of the most promising tools which give hope to patients with no suitable or no available treatment. Patient-specific approaches are particularly needed for common diseases with a broad phenotypic spectrum as well as for rare and yet-undiagnosed disorders. In both cases, there is a need to understand the underlying mechanisms and how to counteract them. Even though, during recent years, we have been observing the blossom of novel therapeutic techniques, there is still a gap to fill between bench and bedside in a patient-specific fashion. In particular, the complexity of genotype-to-phenotype correlations in the context of neurological disorders has dampened the development of successful disease-modifying therapeutics. Animal modeling of human diseases is instrumental in the development of therapies. Currently, zebrafish has emerged as a powerful and convenient model organism for modeling and investigating various neurological disorders. This model has been broadly described as a valuable tool for understanding developmental processes and disease mechanisms, behavioral studies, toxicity, and drug screening. The translatability of findings obtained from zebrafish studies and the broad prospect of human disease modeling paves the way for developing tailored therapeutic strategies. In this review, we will discuss the predictive power of zebrafish in the discovery of novel, precise therapeutic approaches in neurosciences. We will shed light on the advantages and abilities of this in vivo model to develop tailored medicinal strategies. We will also investigate the newest accomplishments and current challenges in the field and future perspectives.
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Affiliation(s)
- Katarzyna Ochenkowska
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | - Aveeva Herold
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | - Éric Samarut
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada.,Department of Neuroscience, Université de Montréal, Montreal, QC, Canada.,Modelis Inc., Montreal, QC, Canada
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9
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Barnaby W, Dorman Barclay HE, Nagarkar A, Perkins M, Teicher G, Trapani JG, Downes GB. GABAA α subunit control of hyperactive behavior in developing zebrafish. Genetics 2022; 220:6519832. [PMID: 35106556 PMCID: PMC8982038 DOI: 10.1093/genetics/iyac011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 01/03/2022] [Indexed: 02/04/2023] Open
Abstract
GABAA receptors mediate rapid responses to the neurotransmitter gamma-aminobutyric acid and are robust regulators of the brain and spinal cord neural networks that control locomotor behaviors, such as walking and swimming. In developing zebrafish, gross pharmacological blockade of these receptors causes hyperactive swimming, which is also a feature of many zebrafish epilepsy models. Although GABAA receptors are important to control locomotor behavior, the large number of subunits and homeostatic compensatory mechanisms have challenged efforts to determine subunit-selective roles. To address this issue, we mutated each of the 8 zebrafish GABAA α subunit genes individually and in pairs using a CRISPR-Cas9 somatic inactivation approach and, then, we examined the swimming behavior of the mutants at 2 developmental stages, 48 and 96 h postfertilization. We found that disrupting the expression of specific pairs of subunits resulted in different abnormalities in swimming behavior at 48 h postfertilization. Mutation of α4 and α5 selectively resulted in longer duration swimming episodes, mutations in α3 and α4 selectively caused excess, large-amplitude body flexions (C-bends), and mutation of α3 and α5 resulted in increases in both of these measures of hyperactivity. At 96 h postfertilization, hyperactive phenotypes were nearly absent, suggesting that homeostatic compensation was able to overcome the disruption of even multiple subunits. Taken together, our results identify subunit-selective roles for GABAA α3, α4, and α5 in regulating locomotion. Given that these subunits exhibit spatially restricted expression patterns, these results provide a foundation to identify neurons and GABAergic networks that control discrete aspects of locomotor behavior.
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Affiliation(s)
- Wayne Barnaby
- Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, Amherst, MA 01003, USA,Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | | | - Akanksha Nagarkar
- Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Matthew Perkins
- Biology Department and Neuroscience Program, Amherst College, Amherst, MA 01002, USA
| | - Gregory Teicher
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003, USA,Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Josef G Trapani
- Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, Amherst, MA 01003, USA,Biology Department and Neuroscience Program, Amherst College, Amherst, MA 01002, USA
| | - Gerald B Downes
- Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, Amherst, MA 01003, USA,Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003, USA,Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA,Corresponding author: Biology Department, Neuroscience and Behavior Graduate Program, and Molecular and Cellular Biology Graduate Program, 611 North Pleasant St., Morrill Science Center, Building 4 North, Amherst, MA 01003, USA.
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10
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Behavioral and histological features of zebrafish following sedation with eugenol or propofol. Appl Anim Behav Sci 2021. [DOI: 10.1016/j.applanim.2021.105482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Sadamitsu K, Shigemitsu L, Suzuki M, Ito D, Kashima M, Hirata H. Characterization of zebrafish GABA A receptor subunits. Sci Rep 2021; 11:6242. [PMID: 33737538 PMCID: PMC7973766 DOI: 10.1038/s41598-021-84646-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/18/2021] [Indexed: 11/23/2022] Open
Abstract
γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, exerts its effect through the activation of GABA receptors. GABAA receptors are ligand-gated chloride channels composed of five subunit proteins. Mammals have 19 different GABAA receptor subunits (α1–6, β1–3, γ1–3, δ, ε, π, θ, and ρ1–3), the physiological properties of which have been assayed by electrophysiology. However, the evolutionary conservation of the physiological characteristics of diverged GABAA receptor subunits remains unclear. Zebrafish have 23 subunits (α1, α2a, α2b, α3–5, α6a, α6b, β1–4, γ1–3, δ, π, ζ, ρ1, ρ2a, ρ2b, ρ3a, and ρ3b), but the electrophysiological properties of these subunits have not been explored. In this study, we cloned the coding sequences for zebrafish GABAA receptor subunits and investigated their expression patterns in larval zebrafish by whole-mount in situ hybridization. We also performed electrophysiological recordings of GABA-evoked currents from Xenopus oocytes injected with one or multiple zebrafish GABAA receptor subunit cRNAs and calculated the half-maximal effective concentrations (EC50s) for each. Our results revealed the spatial expressions and electrophysiological GABA sensitivities of zebrafish GABAA receptors, suggesting that the properties of GABAA receptor subunits are conserved among vertebrates.
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Affiliation(s)
- Kenichiro Sadamitsu
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Leona Shigemitsu
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Marina Suzuki
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Daishi Ito
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Makoto Kashima
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Hiromi Hirata
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan.
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12
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Zaig S, da Silveira Scarpellini C, Montandon G. Respiratory depression and analgesia by opioid drugs in freely behaving larval zebrafish. eLife 2021; 10:63407. [PMID: 33720013 PMCID: PMC8060028 DOI: 10.7554/elife.63407] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 03/11/2021] [Indexed: 12/24/2022] Open
Abstract
An opioid epidemic is spreading in North America with millions of opioid overdoses annually. Opioid drugs, like fentanyl, target the mu opioid receptor system and induce potentially lethal respiratory depression. The challenge in opioid research is to find a safe pain therapy with analgesic properties but no respiratory depression. Current discoveries are limited by lack of amenable animal models to screen candidate drugs. Zebrafish (Danio rerio) is an emerging animal model with high reproduction and fast development, which shares remarkable similarity in their physiology and genome to mammals. However, it is unknown whether zebrafish possesses similar opioid system, respiratory and analgesic responses to opioids than mammals. In freely-behaving larval zebrafish, fentanyl depresses the rate of respiratory mandible movements and induces analgesia, effects reversed by μ-opioid receptor antagonists. Zebrafish presents evolutionary conserved mechanisms of action of opioid drugs, also found in mammals, and constitute amenable models for phenotype-based drug discovery. When it comes to treating severe pain, a doctor’s arsenal is somewhat limited: synthetic or natural opioids such as morphine, fentanyl or oxycodone are often one of the only options available to relieve patients. Yet these compounds can make breathing slower and shallower, quickly depriving the body of oxygen and causing death. This lethal side-effect is particularly devastating as opioids misuse has reached dangerously high levels in the United States, creating an ‘opioid epidemic’ which has claimed the lives of over 80,000 Americans in 2020. It is therefore crucial to find safer drugs that do not have this effect on breathing, but this research has been slowed down by the lack of animal models in which to study the effect of new compounds. Zebrafish are small freshwater fish that reproduce and develop fast, yet they are also remarkably genetically similar to mammals and feature a complex nervous system. However, it is not known whether the effect of opioids on zebrafish is comparable to mammals, and therefore whether these animals can be used to test new drugs for pain relief. To investigate this question, Zaig et al. exposed zebrafish larvae to fentanyl, showing that the fish then exhibited slower lower jaw movements – a sign of decreased breathing. The fish also could also tolerate a painful stimulus for longer, suggesting that this opioid does reduce pain in the animals. Together, these results point towards zebrafish and mammals sharing similar opioid responses, demonstrating that the fish could be used to test potential pain medications. The methods Zaig et al. have developed to establish these results could be harnessed to quickly assess large numbers of drug compounds, as well as decipher how pain emerges and can be stopped.
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Affiliation(s)
- Shenhab Zaig
- Keenan Research Centre for Biomedical Sciences. St. Michael's Hospital Unity Health Toronto, Toronto, Canada
| | | | - Gaspard Montandon
- Keenan Research Centre for Biomedical Sciences. St. Michael's Hospital Unity Health Toronto, Toronto, Canada
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A vertebrate model to reveal neural substrates underlying the transitions between conscious and unconscious states. Sci Rep 2020; 10:15789. [PMID: 32978423 PMCID: PMC7519646 DOI: 10.1038/s41598-020-72669-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/28/2020] [Indexed: 12/16/2022] Open
Abstract
The field of neuropharmacology has not yet achieved a full understanding of how the brain transitions between states of consciousness and drug-induced unconsciousness, or anesthesia. Many small molecules are used to alter human consciousness, but the repertoire of underlying molecular targets, and thereby the genes, are incompletely understood. Here we describe a robust larval zebrafish model of anesthetic action, from sedation to general anesthesia. We use loss of movement under three different conditions, spontaneous movement, electrical stimulation or a tap, as a surrogate for sedation and general anesthesia, respectively. Using these behavioral patterns, we find that larval zebrafish respond to inhalational and IV anesthetics at concentrations similar to mammals. Additionally, known sedative drugs cause loss of spontaneous larval movement but not to the tap response. This robust, highly tractable vertebrate model can be used in the detection of genes and neural substrates involved in the transition from consciousness to unconsciousness.
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14
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Obal D, Wu S, McKinstry-Wu A, Tawfik VL. A Guide to Understanding "State-of-the-Art" Basic Research Techniques in Anesthesiology. Anesth Analg 2020; 131:450-463. [PMID: 32371742 DOI: 10.1213/ane.0000000000004801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Perioperative medicine is changing from a "protocol-based" approach to a progressively personalized care model. New molecular techniques and comprehensive perioperative medical records allow for detection of patient-specific phenotypes that may better explain, or even predict, a patient's response to perioperative stress and anesthetic care. Basic science technology has significantly evolved in recent years with the advent of powerful approaches that have translational relevance. It is incumbent on us as a primarily clinical specialty to have an in-depth understanding of rapidly evolving underlying basic science techniques to incorporate such approaches into our own research, critically interpret the literature, and improve future anesthesia patient care. This review focuses on 3 important and most likely practice-changing basic science techniques: next-generation sequencing (NGS), clustered regularly interspaced short palindromic repeat (CRISPR) modulations, and inducible pluripotent stem cells (iPSCs). Each technique will be described, potential advantages and limitations discussed, open questions and challenges addressed, and future developments outlined. We hope to provide insight for practicing physicians when confronted with basic science articles and encourage investigators to apply "state-of-the-art" technology to their future experiments.
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Affiliation(s)
- Detlef Obal
- From the Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California.,Department of Anesthesiology, Perioperative, and Pain Medicine and Cardiovascular Institute, Stanford University School of Medicine, Stanford, California
| | - Shaogen Wu
- From the Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California
| | - Andrew McKinstry-Wu
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Vivianne L Tawfik
- From the Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California
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