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Abdulzahir A, Klein S, Lor C, Perkins MG, Frelka A, Pearce RA. Changes in Memory, Sedation, and Receptor Kinetics Imparted by the β2-N265M and β3-N265M GABAA Receptor Point Mutations. Int J Mol Sci 2023; 24:ijms24065637. [PMID: 36982709 PMCID: PMC10053577 DOI: 10.3390/ijms24065637] [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: 03/01/2023] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 03/18/2023] Open
Abstract
Point mutations in the β2 (N265S) and β3 (N265M) subunits of γ-amino butyric acid type A receptors (GABAARs) that render them insensitive to the general anesthetics etomidate and propofol have been used to link modulation of β2-GABAARs to sedation and β3-GABAARs to surgical immobility. These mutations also alter GABA sensitivity, and mice carrying the β3-N265M mutation have been reported to have impaired baseline memory. Here, we tested the effects of the β2-N265M and β3-N265M mutations on memory, movement, hotplate sensitivity, anxiety, etomidate-induced sedation, and intrinsic kinetics. We found that both β2-N265M and β3-N265M mice exhibited baseline deficits in the Context Preexposure Facilitation Effect learning paradigm. Exploratory activity was slightly greater in β2-N265M mice, but there were no changes in either genotype in anxiety or hotplate sensitivity. β2-N265M mice were highly resistant to etomidate-induced sedation, and heterozygous mice were partially resistant. In rapid solution exchange experiments, both mutations accelerated deactivation two- to three-fold compared to wild type receptors and prevented modulation by etomidate. This degree of change in the receptor deactivation rate is comparable to that produced by an amnestic dose of etomidate but in the opposite direction, indicating that intrinsic characteristics of GABAARs are optimally tuned under baseline conditions to support mnemonic function.
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Neurosurgical Anesthesia: Optimizing Outcomes with Agent Selection. Biomedicines 2023; 11:biomedicines11020372. [PMID: 36830909 PMCID: PMC9953550 DOI: 10.3390/biomedicines11020372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 01/22/2023] [Indexed: 01/31/2023] Open
Abstract
Anesthesia in neurosurgery embodies a vital element in the development of neurosurgical intervention. This undisputed interest has offered surgeons and anesthesiologists an array of anesthetic selections to utilize, though with this allowance comes the equally essential requirement of implementing a maximally appropriate agent. To date, there remains a lack of consensus and official guidance on optimizing anesthetic choice based on operating priorities including hemodynamic parameters (e.g., CPP, ICP, MAP) in addition to the route of procedure and pathology. In this review, the authors detail the development of neuroanesthesia, summarize the advantages and drawbacks of various anesthetic classes and agents, while lastly cohesively organizing the current literature of randomized trials on neuroanesthesia across various procedures.
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Zeng K, Long J, Li Y, Hu J. Preventing postoperative cognitive dysfunction using anesthetic drugs in elderly patients undergoing noncardiac surgery: a systematic review and meta-analysis. Int J Surg 2023; 109:21-31. [PMID: 36799783 PMCID: PMC10389238 DOI: 10.1097/js9.0000000000000001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/25/2022] [Indexed: 02/18/2023]
Abstract
Postoperative cognitive dysfunction (POCD) is a common neurological system disorder in surgical patients. The choice of anesthetic can potentially reduce POCD. The authors performed this network meta-analysis to compare different anesthetic drugs in reducing the incidence of POCD for elderly people undergoing noncardiac surgery. We searched MEDLINE, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trials comparing the different anesthetic drugs for noncardiac surgery in elderly from inception until July, 2022. The protocol was registered on the PROSPERO database (CRD#42020183014). A total of 34 trials involving 4314 patients undergoing noncardiac surgery in elderly were included. The incidence of POCD for each anesthetic drug was placebo (27.7%), dexmedetomidine (12.9%), ketamine (15.2%), propofol (16.8%), fentanyl (23.9%), midazolam (11.3%), sufentanil (6.3%), sevoflurane (24.0%), and desflurane (28.3%). Pairwise and network meta-analysis showed dexmedetomidine was significantly reducing the incidence of POCD when compared with placebo. Network meta-analysis also suggested dexmedetomidine was significantly reducing the incidence of POCD when compared with sevoflurane. Sufentanil and dexmedetomidine ranked the first and second in reducing the incidence of POCD with the surface under the cumulative ranking curve value of 87.4 and 81.5%. Sufentanil and dexmedetomidine had the greatest possibility to reduce the incidence of POCD for elderly people undergoing noncardiac surgery.
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Affiliation(s)
- Kuan Zeng
- Department of Psychiatry, Wuhan Mental Health Center
- Affiliated Wuhan Mental Health Center, Tongji Medical College of Huazhong University of Science and Technology
- Research Center for Psychological and Health Sciences, China University of Geosciences
| | - Jingyi Long
- Department of Psychiatry, Wuhan Mental Health Center
- Affiliated Wuhan Mental Health Center, Tongji Medical College of Huazhong University of Science and Technology
- Research Center for Psychological and Health Sciences, China University of Geosciences
| | - Yi Li
- Department of Psychiatry, Wuhan Mental Health Center
- Affiliated Wuhan Mental Health Center, Tongji Medical College of Huazhong University of Science and Technology
- Research Center for Psychological and Health Sciences, China University of Geosciences
| | - Jichang Hu
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Li WK, Chen XJC, Altshuler D, Islam S, Spiegler P, Emerson L, Bender M. The incidence of propofol infusion syndrome in critically-ill patients. J Crit Care 2022; 71:154098. [PMID: 35724444 DOI: 10.1016/j.jcrc.2022.154098] [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: 03/15/2022] [Revised: 05/25/2022] [Accepted: 06/01/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE PRIS is a potentially fatal syndrome characterized by various clinical symptoms and abnormalities. Experts suggest that propofol treatment duration ≥48 h or dose ≥83 μg/kg/min is associated with developing PRIS. We hypothesized PRIS might be underdiagnosed due to the overlap of PRIS clinical manifestations with critical illnesses. MATERIALS AND METHODS Multihospital, retrospective study of adult patients who received continuous propofol infusion ≥48 h or dose ≥60μg/kg/min for >24 h since admission were assessed for the development of PRIS. RESULTS The incidence of PRIS was 2.9% with a PRIS-associated mortality rate of 36.8%. In PRIS patients, propofol was administered at a median dose of 36.4 μg/kg/min and over a median duration of 147.0 h. The development of PRIS was observed at a median of 125.0 h post-propofol initiation and a cumulative dose of 276.5 mg/kg. The development of metabolic acidosis (78.9%), cardiac dysfunction (52.6%), hypertriglyceridemia (100%), and rhabdomyolysis (26.3%) were observed in our PRIS patients. CONCLUSION PRIS can often be overlooked and underdiagnosed. It is important to monitor for early signs of PRIS in patients who are on prolonged propofol infusion. Prompt recognition and interventions can minimize the dangers resulting from PRIS.
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Affiliation(s)
- Wai Kin Li
- New York University Langone Hospital - Long Island, NY, USA.
| | | | - Diana Altshuler
- New York University Langone Hospital - Long Island, NY, USA; New York University Langone Health, NY, USA
| | - Shahidul Islam
- New York University Langone Hospital - Long Island, NY, USA
| | - Peter Spiegler
- New York University Langone Hospital - Long Island, NY, USA
| | - Liane Emerson
- New York University Langone Hospital - Long Island, NY, USA
| | - Michael Bender
- New York University Langone Hospital - Long Island, NY, USA
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Singh A, Anjankar AP. Propofol-Related Infusion Syndrome: A Clinical Review. Cureus 2022; 14:e30383. [PMID: 36407194 PMCID: PMC9671386 DOI: 10.7759/cureus.30383] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023] Open
Abstract
Propofol-related infusion syndrome (PRIS) is a lethal condition characterized by multiple organ system failures. It can occur due to prolonged administration of propofol (an anesthetic) in mechanically intubated patients. The main presenting features of this condition include cardiovascular dysfunction with particular emphasis on impairment of cardiovascular contractility, metabolic acidosis, lactic acidosis, rhabdomyolysis, hyperkalaemia, lipidaemia, hepatomegaly, acute renal failure, and eventually mortality in most cases. The significant risk factors that predispose one to PRIS are: critical illnesses, increased serum catecholamines, steroid therapy, obesity, young age (significantly below three years), depleted carbohydrate stores in the body, increased serum lipids, and most importantly, heavy or extended dosage of propofol. The primary pathophysiology behind PRIS is the disruption of the mitochondrial respiratory chain that causes inhibition of adenosine triphosphate (ATP) synthesis and cellular hypoxia. Further, excess lipolysis of adipose tissue occurs, especially in critically ill patients where the energy source is lipid breakdown instead of carbohydrates. This process generates excess free fatty acids (FFAs) that cannot undergo adequate beta-oxidation. These FFAs contribute to the clinical pathology of PRIS. It requires prompt management as it is a fatal condition. The clinicians must observe the patient's electrocardiogram (ECG), serum creatine kinase, lipase, amylase, lactate, liver enzymes, and myoglobin levels in urine, under propofol sedation. Doctors should immediately stop propofol infusion upon noticing any abnormality in these parameters. The other essentials of management of various manifestations of PRIS will be discussed in this article, along with a detailed explanation of the condition, its risk factors, diagnosis, pathophysiology, and presenting features. This article aims to make clinicians more aware of the occurrence of this syndrome so that better ways to manage and treat this condition can be formulated in the future.
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Affiliation(s)
- Aayushi Singh
- Anesthesiology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences, Wardha, IND
| | - Ashish P Anjankar
- Biochemistry, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences, Wardha, IND
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Volkova YA, Rassokhina IV, Kondrakhin EA, Rossokhin AV, Kolbaev SN, Tihonova TB, Kh. Dzhafarov M, Schetinina MA, Chernoburova EI, Vasileva EV, Dmitrenok AS, Kovalev GI, Sharonova IN, Zavarzin IV. Synthesis and Evaluation of Avermectin–Imidazo[1,2-a]pyridine Hybrids as Potent GABAA Receptor Modulators. Bioorg Chem 2022; 127:105904. [DOI: 10.1016/j.bioorg.2022.105904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 05/18/2022] [Accepted: 05/21/2022] [Indexed: 01/08/2023]
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Ghosh AK, Chowdhury M, Kumar Das P. Nipecotic-Acid-Tethered, Naphthalene-Diimide-Based, Orange-Emitting Organic Nanoparticles as Targeted Delivery Vehicle and Diagnostic Probe toward GABA A-Receptor-Enriched Cancer Cells. ACS APPLIED BIO MATERIALS 2021; 4:7563-7577. [PMID: 35006693 DOI: 10.1021/acsabm.1c00830] [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: 01/15/2023]
Abstract
This article demonstrates target-specific cellular imaging of GABA (γ-aminobutyric acid) receptor (GABAAR)-enriched cells (SH-SY5Y and A549) with therapeutic efficacy by naphthalene diimide (NDI)-derived fluorescent organic nanoparticles (FONPs). Self-assembly-driven formation of spherical organic particles by nipecotic-acid-tethered l-aspartic acid appended NDI derivative (NDI-nip) took place in DMSO-water through J-type aggregation. NDI-nip having a naphthyl residue and a nipecotic acid unit at both terminals exhibited aggregation-induced emission (AIE) at and above 60% water content in DMSO because of excimer formation at λem = 579 nm. The orange-emitting NDI-nip FONPs (1:99 v/v DMSO-water) having excellent cell viability and high photostability were used for selective bioimaging and killing of GABAAR-overexpressed cancer cells through target-specific delivery of the anticancer drug curcumin. The fluorescence intensity of NDI-nip FONPs were quenched in GABAAR-enriched neuroblastoma cells (SH-SY5Y) and cancerous cells (A549). Notably, in the presence of GABA, the NDI-nip FONPs exhibited their native fluorescence within the same cell lines. Importantly, no such quenching and regaining of NDI-nip FONP emission in the presence of GABA was noted in the case of the noncancerous cell NIH3T3. The killing efficiency of curcumin-loaded NDI-nip FONPs ([curcumin] = 100 μM and [NDI-nip FONPs] = 50 μM) was significantly higher in the cases of SH-SY5Y (88 ± 3%) and A549 (72 ± 2%) than in NIH3T3 (37 ± 2). The presence of a nipecotic acid moiety facilitated the selective cellular internalization of NDI-nip FONPs into GABAAR-overexpressing cells. Hence, these orange-emitting NDI-nip FONPs may be exploited as a targeted diagnostic probe as well as a drug delivery vehicle for GABAAR-enriched cancer cells.
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Affiliation(s)
- Anup Kumar Ghosh
- School of Biological Sciences, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700032, India
| | - Monalisa Chowdhury
- School of Biological Sciences, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700032, India
| | - Prasanta Kumar Das
- School of Biological Sciences, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700032, India
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Figueroa AG, Benkwitz C, Surges G, Kunz N, Homanics GE, Pearce RA. Hippocampal β2-GABA A receptors mediate LTP suppression by etomidate and contribute to long-lasting feedback but not feedforward inhibition of pyramidal neurons. J Neurophysiol 2021; 126:1090-1100. [PMID: 34406874 PMCID: PMC8560413 DOI: 10.1152/jn.00303.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The general anesthetic etomidate, which acts through γ-aminobutyric acid type A (GABAA) receptors, impairs the formation of new memories under anesthesia. This study addresses the molecular and cellular mechanisms by which this occurs. Here, using a new line of genetically engineered mice carrying the GABAA receptor (GABAAR) β2-N265M mutation, we tested the roles of receptors that incorporate GABAA receptor β2 versus β3 subunits to suppression of long-term potentiation (LTP), a cellular model of learning and memory. We found that brain slices from β2-N265M mice resisted etomidate suppression of LTP, indicating that the β2-GABAARs are an essential target in this model. As these receptors are most heavily expressed by interneurons in the hippocampus, this finding supports a role for interneuron modulation in etomidate control of synaptic plasticity. Nevertheless, β2 subunits are also expressed by pyramidal neurons, so they might also contribute. Therefore, using a previously established line of β3-N265M mice, we also examined the contributions of β2- versus β3-GABAARs to GABAA,slow dendritic inhibition, because dendritic inhibition is particularly well suited to controlling synaptic plasticity. We also examined their roles in long-lasting suppression of population activity through feedforward and feedback inhibition. We found that both β2- and β3-GABAARs contribute to GABAA,slow inhibition and that both β2- and β3-GABAARs contribute to feedback inhibition, whereas only β3-GABAARs contribute to feedforward inhibition. We conclude that modulation of β2-GABAARs is essential to etomidate suppression of LTP. Furthermore, to the extent that this occurs through GABAARs on pyramidal neurons, it is through modulation of feedback inhibition.NEW & NOTEWORTHY Etomidate exerts its anesthetic actions through GABAA receptors. However, the mechanism remains unknown. Here, using a hippocampal brain slice model, we show that β2-GABAARs are essential to this effect. We also show that these receptors contribute to long-lasting dendritic inhibition in feedback but not feedforward inhibition of pyramidal neurons. These findings hold implications for understanding how anesthetics block memory formation and, more generally, how inhibitory circuits control learning and memory.
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Affiliation(s)
- Alexander G Figueroa
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Claudia Benkwitz
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Gabe Surges
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Nicholas Kunz
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Gregg E Homanics
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin
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Castellano D, Shepard RD, Lu W. Looking for Novelty in an "Old" Receptor: Recent Advances Toward Our Understanding of GABA ARs and Their Implications in Receptor Pharmacology. Front Neurosci 2021; 14:616298. [PMID: 33519367 PMCID: PMC7841293 DOI: 10.3389/fnins.2020.616298] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Diverse populations of GABAA receptors (GABAARs) throughout the brain mediate fast inhibitory transmission and are modulated by various endogenous ligands and therapeutic drugs. Deficits in GABAAR signaling underlie the pathophysiology behind neurological and neuropsychiatric disorders such as epilepsy, anxiety, and depression. Pharmacological intervention for these disorders relies on several drug classes that target GABAARs, such as benzodiazepines and more recently neurosteroids. It has been widely demonstrated that subunit composition and receptor stoichiometry impact the biophysical and pharmacological properties of GABAARs. However, current GABAAR-targeting drugs have limited subunit selectivity and produce their therapeutic effects concomitantly with undesired side effects. Therefore, there is still a need to develop more selective GABAAR pharmaceuticals, as well as evaluate the potential for developing next-generation drugs that can target accessory proteins associated with native GABAARs. In this review, we briefly discuss the effects of benzodiazepines and neurosteroids on GABAARs, their use as therapeutics, and some of the pitfalls associated with their adverse side effects. We also discuss recent advances toward understanding the structure, function, and pharmacology of GABAARs with a focus on benzodiazepines and neurosteroids, as well as newly identified transmembrane proteins that modulate GABAARs.
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Affiliation(s)
- David Castellano
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ryan David Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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Lor C, Perouansky M, Pearce RA. Isoflurane Potentiation of GABA A Receptors Is Reduced but Not Eliminated by the β3(N265M) Mutation. Int J Mol Sci 2020; 21:ijms21249534. [PMID: 33333797 PMCID: PMC7765171 DOI: 10.3390/ijms21249534] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 12/16/2022] Open
Abstract
Background: Mice carrying the GABAA receptor β3(N265M) point mutation, which renders receptors incorporating β3-subunits insensitive to many general anesthetics, have been used experimentally to link modulation of different receptor subtypes to distinct behavioral endpoints. Remarkably, however, the effect of the mutation on the susceptibility to modulation by isoflurane (a standard reference agent for inhalational vapors) has never been tested directly. Therefore, we compared the modulation by isoflurane of expressed α5β3(N265M)γ2L receptors with their wild type counterparts. Methods: Using whole-cell electrophysiological recording and rapid solution exchange techniques, we tested the effects of isoflurane at concentrations ranging from 80 μM to 320 μM on currents activated by 1 μM GABA. We measured drug modulation of wild-type α5β3γ2L GABAA receptors and their counterparts harboring the β3(N265M) mutation. Results: Currents elicited by GABA were enhanced two- to four-fold by isoflurane, in a concentration-dependent manner. Under the same conditions, receptors incorporating the β3(N265M) mutation were enhanced by approximately 1.5- to two-fold; i.e., modulation by isoflurane was attenuated by approximately one-half. Direct activation by isoflurane was also present in mutant receptors but also attenuated. Conclusions: In contrast to the complete insensitivity of β3(N265M) mutant receptors to etomidate and propofol, the mutation has only a partial effect on receptor modulation by isoflurane. Therefore, the persistence of isoflurane effects in mutant mice does not exclude a possible contribution of β3-GABAA receptors.
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Qu JZ, Kao LW, Smith JE, Kuo A, Xue A, Iyer MH, Essandoh MK, Dalia AA. Brain Protection in Aortic Arch Surgery: An Evolving Field. J Cardiothorac Vasc Anesth 2020; 35:1176-1188. [PMID: 33309497 DOI: 10.1053/j.jvca.2020.11.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 12/11/2022]
Abstract
Despite advances in cardiac surgery and anesthesia, the rates of brain injury remain high in aortic arch surgery requiring circulatory arrest. The mechanisms of brain injury, including permanent and temporary neurologic dysfunction, are multifactorial, but intraoperative brain ischemia is likely a major contributor. Maintaining optimal cerebral perfusion during cardiopulmonary bypass and circulatory arrest is the key component of intraoperative management for aortic arch surgery. Various brain monitoring modalities provide different information to improve cerebral protection. Electroencephalography gives crucial data to ensure minimal cerebral metabolism during deep hypothermic circulatory arrest, transcranial Doppler directly measures cerebral arterial blood flow, and near-infrared spectroscopy monitors regional cerebral oxygen saturation. Various brain protection techniques, including hypothermia, cerebral perfusion, pharmacologic protection, and blood gas management, have been used during interruption of systemic circulation, but the optimal strategy remains elusive. Although deep hypothermic circulatory arrest and retrograde cerebral perfusion have their merits, there have been increasing reports about the use of antegrade cerebral perfusion, obviating the need for deep hypothermia. With controversy and variability of surgical practices, moderate hypothermia, when combined with unilateral antegrade cerebral perfusion, is considered safe for brain protection in aortic arch surgery performed with circulatory arrest. The neurologic outcomes of brain protection in aortic arch surgery largely depend on the following three major components: cerebral temperature, circulatory arrest time, and cerebral perfusion during circulatory arrest. The optimal brain protection strategy should be individualized based on comprehensive monitoring and stems from well-executed techniques that balance the major components contributing to brain injury.
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Affiliation(s)
- Jason Z Qu
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Lee-Wei Kao
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Jennifer E Smith
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Alexander Kuo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Albert Xue
- Department of Cardiac Surgery, Nanjing Drum Tower Hospital, Nanjing, China
| | - Manoj H Iyer
- Department of Anesthesiology, The Ohio State University Medical Center, Columbus, OH
| | - Michael K Essandoh
- Department of Anesthesiology, The Ohio State University Medical Center, Columbus, OH
| | - Adam A Dalia
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
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Drexler B, Grenz J, Grasshoff C, Antkowiak B. Allopregnanolone Enhances GABAergic Inhibition in Spinal Motor Networks. Int J Mol Sci 2020; 21:ijms21197399. [PMID: 33036451 PMCID: PMC7582554 DOI: 10.3390/ijms21197399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/28/2020] [Accepted: 10/01/2020] [Indexed: 11/16/2022] Open
Abstract
The neurosteroid allopregnanolone (ALLO) causes unconsciousness by allosteric modulation of γ-aminobutyric acid type A (GABAA) receptors, but its actions on the spinal motor networks are unknown. We are therefore testing the hypothesis that ALLO attenuates the action potential firing of spinal interneurons and motoneurons predominantly via enhancing tonic, but not synaptic GABAergic inhibition. We used video microscopy to assess motoneuron-evoked muscle activity in organotypic slice cultures prepared from the spinal cord and muscle tissue. Furthermore, we monitored GABAA receptor-mediated currents by performing whole-cell voltage-clamp recordings. We found that ALLO (100 nM) reduced the action potential firing of spinal interneurons by 27% and that of α-motoneurons by 33%. The inhibitory effects of the combination of propofol (1 µM) and ALLO on motoneuron-induced muscle contractions were additive. Moreover, ALLO evoked a tonic, GABAA receptor-mediated current (amplitude: 41 pA), without increasing phasic GABAergic transmission. Since we previously showed that at a clinically relevant concentration of 1 µM propofol enhanced phasic, but not tonic GABAergic inhibition, we conclude that ALLO and propofol target distinct subpopulations of GABAA receptors. These findings provide first evidence that the combined application of ALLO and propofol may help to reduce intraoperative movements and undesired side effects that are frequently observed under total intravenous anesthesia.
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de Oliveira TM, van Beek L, Shilliday F, Debreczeni JÉ, Phillips C. Cryo-EM: The Resolution Revolution and Drug Discovery. SLAS DISCOVERY 2020; 26:17-31. [PMID: 33016175 DOI: 10.1177/2472555220960401] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Single-particle cryogenic electron microscopy (cryo-EM) has been elevated to the mainstream of structural biology propelled by technological advancements in numerous fronts, including imaging analysis and the development of direct electron detectors. The drug discovery field has watched with (initial) skepticism and wonder at the progression of the technique and how it revolutionized the molecular understanding of previously intractable targets. This article critically assesses how cryo-EM has impacted drug discovery in diverse therapeutic areas. Targets that have been brought into the realm of structure-based drug design by cryo-EM and are thus reviewed here include membrane proteins like the GABAA receptor, several TRP channels, and G protein-coupled receptors, and multiprotein complexes like the ribosomes, the proteasome, and eIF2B. We will describe these studies highlighting the achievements, challenges, and caveats.
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Affiliation(s)
| | - Lotte van Beek
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Fiona Shilliday
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Judit É Debreczeni
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Chris Phillips
- Structure, Biophysics and FBLG, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
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Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation. Pharmaceuticals (Basel) 2020; 13:ph13040062. [PMID: 32260535 PMCID: PMC7243109 DOI: 10.3390/ph13040062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 02/07/2023] Open
Abstract
Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na+ and K+ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, 2-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na+ and K+ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.
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Vega Alanis BA, Iorio MT, Silva LL, Bampali K, Ernst M, Schnürch M, Mihovilovic MD. Allosteric GABA A Receptor Modulators-A Review on the Most Recent Heterocyclic Chemotypes and Their Synthetic Accessibility. Molecules 2020; 25:E999. [PMID: 32102309 PMCID: PMC7070463 DOI: 10.3390/molecules25040999] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 11/17/2022] Open
Abstract
GABAA receptor modulators are structurally almost as diverse as their target protein. A plethora of heterocyclic scaffolds has been described as modulating this extremely important receptor family. Some made it into clinical trials and, even on the market, some were dismissed. This review focuses on the synthetic accessibility and potential for library synthesis of GABAA receptor modulators containing at least one heterocyclic scaffold, which were disclosed within the last 10 years.
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Affiliation(s)
- Blanca Angelica Vega Alanis
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/193, 1060 Vienna, Austria; (B.A.V.A.); (M.T.I.); (M.D.M.)
| | - Maria Teresa Iorio
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/193, 1060 Vienna, Austria; (B.A.V.A.); (M.T.I.); (M.D.M.)
| | - Luca L. Silva
- Department of Anesthesiology and Intensive Care Medicine, Charité–Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany;
| | - Konstantina Bampali
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria;
| | - Margot Ernst
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria;
| | - Michael Schnürch
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/193, 1060 Vienna, Austria; (B.A.V.A.); (M.T.I.); (M.D.M.)
| | - Marko D. Mihovilovic
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/193, 1060 Vienna, Austria; (B.A.V.A.); (M.T.I.); (M.D.M.)
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