1
|
Li GG, Xu YH, Sun MZ, Bing YH, Jin WZ, Qiu DL. Etomidate enhances cerebellar CF-PC synaptic plasticity through CB1 receptor/PKA cascade in vitro in mice. Neurosci Lett 2024; 826:137733. [PMID: 38492880 DOI: 10.1016/j.neulet.2024.137733] [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: 02/20/2024] [Revised: 02/28/2024] [Accepted: 03/13/2024] [Indexed: 03/18/2024]
Abstract
Etomidate (ET) is a widely used intravenous imidazole general anesthetic, which depresses the cerebellar neuronal activity by modulating various receptors activity and synaptic transmission. In this study, we investigated the effects of ET on the cerebellar climbing fiber-Purkinje cells (CF-PC) plasticity in vitro in mice using whole-cell recording technique and pharmacological methods. Our results demonstrated that CF tetanic stimulation produced a mGluR1-dependent long-term depression (LTD) of CF-PC excitatory postsynaptic currents (EPSCs), which was enhanced by bath application of ET (10 µM). Blockade of mGluR1 receptor with JNJ16259685, ET triggered the tetanic stimulation to induce a CF-PC LTD accompanied with an increase in paired-pulse ratio (PPR). The ET-triggered CF-PC LTD was abolished by extracellular administration of an N-methyl-(D)-aspartate (NMDA) receptor antagonist, D-APV, as well as by intracellular blockade of NMDA receptors activity with MK801. Furthermore, blocking cannabinoids 1 (CB1) receptor with AM251 or chelating intracellular Ca2+ with BAPTA, ET failed to trigger the CF-PC LTD. Moreover, the ET-triggered CF-PC LTD was abolished by inhibition of protein kinase A (PKA), but not by inhibition of protein kinase C inhibiter. The present results suggest that ET acts on postsynaptic NMDA receptor resulting in an enhancement of the cerebellar CF-PC LTD through CB1 receptor/PKA cascade in vitro in mice. These results provide new evidence and possible mechanism for ET anesthesia to affect motor learning and motor coordination by regulating cerebellar CF-PC LTD.
Collapse
Affiliation(s)
- Guang-Gao Li
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Department of Orthopedics, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - Ying-Han Xu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Department of Orthopedics, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - Ming-Ze Sun
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Institute of Brain Science, Jilin Medical University, Jilin City, Jilin Province 132013, China
| | - Yan-Hua Bing
- Functional Experiment Center, College of Medicine, Yanbian University, Yanji City, Jilin Province 133000, China
| | - Wen-Zhe Jin
- Department of Pain, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - De-Lai Qiu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Institute of Brain Science, Jilin Medical University, Jilin City, Jilin Province 132013, China; Department of Physiology, College of Basic Medicine, Jilin Meidcal University, Jilin City, Jilin Province 132013, China.
| |
Collapse
|
2
|
Wu J, Zhao M, Jin YC, Li M, Yu KX, Yu HB. Schisandrin B, a dual positive allosteric modulator of GABA A and glycine receptors, alleviates seizures in multiple mouse models. Acta Pharmacol Sin 2024; 45:465-479. [PMID: 38017298 PMCID: PMC10834591 DOI: 10.1038/s41401-023-01195-3] [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: 07/26/2023] [Accepted: 11/09/2023] [Indexed: 11/30/2023] Open
Abstract
Epilepsy is a prevalent and severe neurological disorder and approximately 30% of patients are resistant to existing medications. It is of utmost importance to develop alternative therapies to treat epilepsy. Schisandrin B (SchB) is a major bioactive constituent of Schisandra chinensis (Turcz.) Baill and has multiple neuroprotective effects, sedative and hypnotic activities. In this study, we investigated the antiseizure effect of SchB in various mouse models of seizure and explored the underlying mechanisms. Pentylenetetrazole (PTZ), strychnine (STR), and pilocarpine-induced mouse seizure models were established. We showed that injection of SchB (10, 30, 60 mg/kg, i.p.) dose-dependently delayed the onset of generalized tonic-clonic seizures (GTCS), reduced the incidence of GTCS and mortality in PTZ and STR models. Meanwhile, injection of SchB (30 mg/kg, i.p.) exhibited therapeutic potential in pilocarpine-induced status epilepticus model, which was considered as a drug-resistant model. In whole-cell recording from CHO/HEK-239 cells stably expressing recombinant human GABAA receptors (GABAARs) and glycine receptors (GlyRs) and cultured hippocampal neurons, co-application of SchB dose-dependently enhanced GABA or glycine-induced current with EC50 values at around 5 μM, and application of SchB (10 μM) alone did not activate the channels in the absence of GABA or glycine. Furthermore, SchB (10 μM) eliminated both PTZ-induced inhibition on GABA-induced current (IGABA) and strychnine (STR)-induced inhibition on glycine-induced current (Iglycine). Moreover, SchB (10 μM) efficiently rescued the impaired GABAARs associated with genetic epilepsies. In addition, the homologous mutants in both GlyRs-α1(S267Q) and GABAARs-α1(S297Q)β2(N289S)γ2L receptors by site-directed mutagenesis tests abolished SchB-induced potentiation of IGABA and Iglycine. In conclusion, we have identified SchB as a natural positive allosteric modulator of GABAARs and GlyRs, supporting its potential as alternative therapies for epilepsy.
Collapse
Affiliation(s)
- Jun Wu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Miao Zhao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yu-Chen Jin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Min Li
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Ke-Xin Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Hai-Bo Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
| |
Collapse
|
3
|
Menzikov SA, Zaichenko DM, Moskovtsev AA, Morozov SG, Kubatiev AA. Phenols and GABA A receptors: from structure and molecular mechanisms action to neuropsychiatric sequelae. Front Pharmacol 2024; 15:1272534. [PMID: 38303988 PMCID: PMC10831359 DOI: 10.3389/fphar.2024.1272534] [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: 08/04/2023] [Accepted: 01/03/2024] [Indexed: 02/03/2024] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABAARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl-) and bicarbonate (HCO3 -) ions by their passive permeability through the ion channel pore. GABAARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols. The wide chemical and structural variability of phenols suggest similar and different binding sites on GABAARs, allowing them to manifest themselves as activators, inhibitors, or allosteric ligands of GABAAR function. Interest in phenols is associated with their great potential for GABAAR modulation, but also with their subsequent negative or positive role in neurological and psychiatric disorders. This review focuses on the GABAergic deficit hypotheses during neurological and psychiatric disorders induced by various phenols. We summarize the structure-activity relationship of general phenol groups concerning their differential roles in the manifestation of neuropsychiatric symptoms. We describe and analyze the role of GABAAR subunits in manifesting various neuropathologies and the molecular mechanisms underlying their modulation by phenols. Finally, we discuss how phenol drugs can modulate GABAAR activity via desensitization and resensitization. We also demonstrate a novel pharmacological approach to treat neuropsychiatric disorders via regulation of receptor phosphorylation/dephosphorylation.
Collapse
|
4
|
Gong JH, Zhang CM, Wu B, Zhang ZX, Zhou ZY, Zhu JH, Liu H, Rong Y, Yin Q, Chen YT, Zheng R, Yang GZ, Yang XF, Chen S. Central and peripheral analgesic active components of triterpenoid saponins from Stauntonia chinensis and their action mechanism. Front Pharmacol 2023; 14:1275041. [PMID: 37908974 PMCID: PMC10613692 DOI: 10.3389/fphar.2023.1275041] [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: 08/09/2023] [Accepted: 09/21/2023] [Indexed: 11/02/2023] Open
Abstract
Triterpenoid saponins from Stauntonia chinensis have been proven to be a potential candidate for inflammatory pain relief. Our pharmacological studies confirmed that the analgesic role of triterpenoid saponins from S. chinensis occurred via a particular increase in the inhibitory synaptic response in the cortex at resting state and the modulation of the capsaicin receptor. However, its analgesic active components and whether its analgesic mechanism are limited to this are not clear. In order to further determine its active components and analgesic mechanism, we used the patch clamp technique to screen the chemical components that can increase inhibitory synaptic response and antagonize transient receptor potential vanilloid 1, and then used in vivo animal experiments to evaluate the analgesic effect of the selected chemical components. Finally, we used the patch clamp technique and molecular biology technology to study the analgesic mechanism of the selected chemical components. The results showed that triterpenoid saponins from S. chinensis could enhance the inhibitory synaptic effect and antagonize the transient receptor potential vanilloid 1 through different chemical components, and produce central and peripheral analgesic effects. The above results fully reflect that "traditional Chinese medicine has multi-component, multi-target, and multi-channel synergistic regulation".
Collapse
Affiliation(s)
- Ji-Hong Gong
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Chang-Ming Zhang
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Bo Wu
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Zi-Xun Zhang
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Zhong-Yan Zhou
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Jia-Hui Zhu
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Han Liu
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Yi Rong
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Qian Yin
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Ya-Ting Chen
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Rong Zheng
- Gynecology Department, Hubei Maternal and Child Health Hospital, Wuhan, China
| | - Guang-Zhong Yang
- College of Pharmacy, South-Central Minzu University, Wuhan, China
| | - Xiao-Fei Yang
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| | - Su Chen
- Key Laboratory of Cognitive Science of State Ethnic Affairs Commission, Hubei Key Laboratory of Medical Information Analysis and Tumor Diagnosis and Treatment, College of Biomedical Engineering, South-Central Minzu University, Wuhan, China
| |
Collapse
|
5
|
Fu H, Zhou J, Li S, Zhang Y, Chen Z, Yang Y, Li A, Wang D. Isoflurane impairs olfaction by increasing neuronal activity in the olfactory bulb. Acta Physiol (Oxf) 2023; 239:e14009. [PMID: 37330999 DOI: 10.1111/apha.14009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/16/2023] [Accepted: 06/05/2023] [Indexed: 06/20/2023]
Abstract
AIM General anesthesia can induce cognitive deficits in both humans and rodents, correlating with pathological alterations in the hippocampus. However, whether general anesthesia affects olfactory behaviors remains controversial as clinical studies have produced inconsistent results. Therefore, we aimed to investigate how olfactory behaviors and neuronal activity are affected by isoflurane exposure in adult mice. METHODS The olfactory detection test, olfactory sensitivity test, and olfactory preference/avoidance test were used to examine olfactory function. In vivo electrophysiology was performed in awake, head-fixed mice to record single-unit spiking and local field potentials in the olfactory bulb (OB). We also performed patch-clamp recordings of mitral cell activity. For morphological studies, immunofluorescence and Golgi-Cox staining were applied. RESULTS Repeated exposure to isoflurane impaired olfactory detection in adult mice. The main olfactory epithelium, the first region exposed to anesthetics, displayed increased proliferation of basal stem cells. In the OB, a crucial hub for olfactory processing, repeated isoflurane exposure increased the odor responses of mitral/tufted cells. Furthermore, the odor-evoked high gamma response was decreased after isoflurane exposure. Whole-cell recordings further indicated that repeated isoflurane exposure increased the excitability of mitral cells, which may be due to weakened inhibitory input in isoflurane-exposed mice. In addition, elevated astrocyte activation and glutamate transporter-1 expression in the OB were observed in isoflurane-exposed mice. CONCLUSIONS Our findings indicate that repeated isoflurane exposure impairs olfactory detection by increasing neuronal activity in the OB in adult mice.
Collapse
Affiliation(s)
- Hanyu Fu
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Jingwei Zhou
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
- Schools of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Shan Li
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Ying Zhang
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhiyun Chen
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yingying Yang
- Schools of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| |
Collapse
|
6
|
Pan W, Chu CP, Qiu DL. Etomidate Depresses Spontaneous Complex Spikes Activity of Cerebellar Purkinje Cells via Cannabinoid 1 Receptor in vivo in Mice. Pharmacology 2023; 108:469-477. [PMID: 37607511 DOI: 10.1159/000531680] [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: 02/09/2023] [Accepted: 06/12/2023] [Indexed: 08/24/2023]
Abstract
INTRODUCTION Complex spikes (CSs) activity of cerebellar Purkinje cells plays critical roles in motor coordination and motor learning by transferring information to cerebellar cortex, which is an accessible and useful model for neurophysiological investigation. Etomidate is an ultrashort-acting nonbarbiturate intravenous anesthetic, which inhibits the spontaneous activity of cerebellar Purkinje cells through activation of GABAA and glycine receptors in vivo in mice. However, the effect of etomidate on the spontaneous CSs activity of cerebellar Purkinje cells in living mouse is not clear. METHODS We here investigated the effects of etomidate on spontaneous CSs activity of cerebellar Purkinje cell in urethane-anesthetized mice by electrophysiology recording technique and pharmacological methods. RESULTS Our results showed that cerebellar surface perfusion of etomidate significantly depressed the activity of spontaneous CSs, which exhibited decreases in the number of spikelets and the area under curve (AUC) of the CSs. The etomidate-produced inhibition of CSs activity was persisted in the presence of GABAA and glycine receptors antagonists. However, application of cannabinoid 1 (CB1) receptor antagonist, AM-251, completely blocked the etomidate-induced inhibition of CSs. Furthermore, application of the CB1 receptor agonist, WIN55212-2, induced a decrease of CSs. Moreover, in the presence of a specific protein kinase A (PKA) inhibitor, KT5720, etomidate failed to produce decreases in the spikelets number and the AUC of the spontaneous CSs. CONCLUSION These results indicate that cerebellar surface application of etomidate facilitates CB1 receptor activity resulting in a depression of spontaneous CSs activity of Purkinje cells via PKA signaling pathway in mouse cerebellar cortex. Our present results suggest that the etomidate administration may impair the function of cerebellar cortical neuronal circuitry by inhibition of the climbing fiber - Purkinje cells synaptic transmission through activation of CB1 receptors in vivo in mice.
Collapse
Affiliation(s)
- Wen Pan
- Department of Basic Medical Science, Jiangsu Vocational College of Medicine, Yancheng, China
| | - Chun-Ping Chu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin City, China
| | - De-Lai Qiu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin City, China
| |
Collapse
|
7
|
Gouveia FV, Lea‐Banks H, Aubert I, Lipsman N, Hynynen K, Hamani C. Anesthetic-loaded nanodroplets with focused ultrasound reduces agitation in Alzheimer's mice. Ann Clin Transl Neurol 2023; 10:507-519. [PMID: 36715553 PMCID: PMC10109287 DOI: 10.1002/acn3.51737] [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: 11/03/2022] [Revised: 01/03/2023] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVE Alzheimer's disease (AD) is often associated with neuropsychiatric symptoms, including agitation and aggressive behavior. These symptoms increase with disease severity, ranging from 10% in mild cognitive impairment to 50% in patients with moderate-to-severe AD, pose a great risk for self-injury and injury to caregivers, result in high rates of institutionalization and great suffering for patients and families. Current pharmacological therapies have limited efficacy and a high potential for severe side effects. Thus, there is a growing need to develop novel therapeutics tailored to safely and effectively reduce agitation and aggressive behavior in AD. Here, we investigate for the first time the use of focused ultrasound combined with anesthetic-loaded nanodroplets (nanoFUS) targeting the amygdala (key structure in the neurocircuitry of agitation) as a novel minimally invasive tool to modulate local neural activity and reduce agitation and aggressive behavior in the TgCRND8 AD transgenic mice. METHODS Male and female animals were tested in the resident-intruder (i.e., aggressive behavior) and open-field tests (i.e., motor agitation) for baseline measures, followed by treatment with active- or sham-nanoFUS. Behavioral testing was then repeated after treatment. RESULTS Active-nanoFUS neuromodulation reduced aggressive behavior and agitation in male mice, as compared to sham-treated controls. Treatment with active-nanoFUS increased the time male mice spent in social-non-aggressive behaviors. INTERPRETATION Our results show that neuromodulation with active-nanoFUS may be a potential therapeutic tool for the treatment of neuropsychiatric symptoms, with special focus on agitation and aggressive behaviors. Further studies are necessary to establish cellular, molecular and long-term behavioral changes following treatment with nanoFUS.
Collapse
Affiliation(s)
- Flavia Venetucci Gouveia
- Biological Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
- Neurosciences and Mental HealthThe Hospital for Sick ChildrenTorontoOntarioM5G 1X8Canada
| | - Harriet Lea‐Banks
- Physical Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
| | - Isabelle Aubert
- Biological Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
- Laboratory Medicine & PathobiologyUniversity of TorontoTorontoOntarioM5S 1A1Canada
- Hurvitz Brain Sciences Program, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
| | - Nir Lipsman
- Biological Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
- Hurvitz Brain Sciences Program, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
- Harquail Centre for Neuromodulation, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
- Division of NeurosurgeryUniversity of TorontoTorontoOntarioM5T 1P5Canada
| | - Kullervo Hynynen
- Physical Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
- Hurvitz Brain Sciences Program, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
- Department of Medical BiophysicsUniversity of TorontoTorontoOntarioM5S 1A1Canada
- Institute of Biomedical Engineering, University of TorontoTorontoOntarioM5S 1A1Canada
| | - Clement Hamani
- Biological Sciences PlatformSunnybrook Research InstituteTorontoOntarioM4N 3M5Canada
- Hurvitz Brain Sciences Program, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
- Harquail Centre for Neuromodulation, Sunnybrook Health Sciences CentreTorontoOntarioM4N 3M5Canada
- Division of NeurosurgeryUniversity of TorontoTorontoOntarioM5T 1P5Canada
| |
Collapse
|
8
|
Qin Y, Mahdavi A, Bertschy M, Anderson PM, Kulikova S, Pinault D. The psychotomimetic ketamine disrupts the transfer of late sensory information in the corticothalamic network. Eur J Neurosci 2023; 57:440-455. [PMID: 36226598 PMCID: PMC10092610 DOI: 10.1111/ejn.15845] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 08/17/2022] [Accepted: 09/01/2022] [Indexed: 02/04/2023]
Abstract
In prodromal and early schizophrenia, disorders of attention and perception are associated with structural and chemical brain abnormalities and with dysfunctional corticothalamic networks exhibiting disturbed brain rhythms. The underlying mechanisms are elusive. The non-competitive NMDA receptor antagonist ketamine simulates the symptoms of prodromal and early schizophrenia, including disturbances in ongoing and task & sensory-related broadband beta-/gamma-frequency (17-29 Hz/30-80 Hz) oscillations in corticothalamic networks. In normal healthy subjects and rodents, complex integration processes, like sensory perception, induce transient, large-scale synchronised beta/gamma oscillations in a time window of a few hundred ms (200-700 ms) after the presentation of the object of attention (e.g., sensory stimulation). Our goal was to use an electrophysiological multisite network approach to investigate, in lightly anesthetised rats, the effects of a single psychotomimetic dose (2.5 mg/kg, subcutaneous) of ketamine on sensory stimulus-induced oscillations. Ketamine transiently increased the power of baseline beta/gamma oscillations and decreased sensory-induced beta/gamma oscillations. In addition, it disrupted information transferability in both the somatosensory thalamus and the related cortex and decreased the sensory-induced thalamocortical connectivity in the broadband gamma range. The present findings support the hypothesis that NMDA receptor antagonism disrupts the transfer of perceptual information in the somatosensory cortico-thalamo-cortical system.
Collapse
Affiliation(s)
- Yi Qin
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie cognitive et physiopathologie de la schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de médecine, Strasbourg, France
- Centre de Recherche en Biomédecine de Strasbourg (CRBS), Strasbourg, France
- Netherlands Institute for Neuroscience, The Netherlands
| | - Ali Mahdavi
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie cognitive et physiopathologie de la schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de médecine, Strasbourg, France
- Centre de Recherche en Biomédecine de Strasbourg (CRBS), Strasbourg, France
- The University of Freiburg, Bernstein Center Freiburg, Freiburg, Germany
| | - Marine Bertschy
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie cognitive et physiopathologie de la schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de médecine, Strasbourg, France
- Centre de Recherche en Biomédecine de Strasbourg (CRBS), Strasbourg, France
| | - Paul M Anderson
- Dept. Cognitive Neurobiology, Center for Brain Research, Medical University Vienna, Austria
| | - Sofya Kulikova
- National Research University Higher School of Economics, Perm, Russia
| | - Didier Pinault
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie cognitive et physiopathologie de la schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de médecine, Strasbourg, France
- Centre de Recherche en Biomédecine de Strasbourg (CRBS), Strasbourg, France
| |
Collapse
|
9
|
Seto T. General anesthetic binding mode via hydration with weak affinity and molecular discrimination: General anesthetic dissolution in interfacial water of the common binding site of GABA A receptor. Biophys Physicobiol 2023; 20:e200005. [PMID: 38496235 PMCID: PMC10941959 DOI: 10.2142/biophysico.bppb-v20.0005] [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: 07/04/2022] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
The GABAA receptor (GABAAR) is a target channel for the loss of awareness of general anesthesia. General anesthetic (GA) spans a wide range of chemical structures, such as monatomic molecules, barbital acids, phenols, ethers, and alkanes. GA has a weak binding affinity, and the affinity has a characteristic that correlates with the solubility in olive oil rather than the molecular shape. The GA binding site of GABAAR is common to GAs and exists in the transmembrane domain of the GABAAR intersubunit. In this study, the mechanism of GA binding, which allows binding of various GAs with intersubunit selectivity, was elucidated from the hydration analysis of the binding site. Regardless of the diverse GA chemical structures, a strong correlation was observed between the binding free energy and total dehydration number of the binding process. The GA binding free energy was more involved in the binding dehydration and showed molecular recognition that allowed for the binding of various GA structures via binding site hydration. We regarded the GA substitution for the interfacial water molecule of the binding site as a dissolution into the interfacial hydration layer. The elucidation of the GA binding mechanism mediated by hydration at the GABAAR common binding site provides a rationale for the combined use of anesthetics in medical practice and its combination adjustments via drug interactions.
Collapse
Affiliation(s)
- Tomoyoshi Seto
- Department of Anesthesiology, School of Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| |
Collapse
|
10
|
Sikstus S, Benkherouf AY, Soini SL, Uusi-Oukari M. The Influence of AA29504 on GABA A Receptor Ligand Binding Properties and Its Implications on Subtype Selectivity. Neurochem Res 2022; 47:667-678. [PMID: 34727270 PMCID: PMC8847198 DOI: 10.1007/s11064-021-03475-y] [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: 06/04/2021] [Revised: 09/03/2021] [Accepted: 10/27/2021] [Indexed: 10/26/2022]
Abstract
The unique pharmacological properties of δ-containing γ-aminobutyric acid type A receptors (δ-GABAARs) make them an attractive target for selective and persistent modulation of neuronal excitability. However, the availability of selective modulators targeting δ-GABAARs remains limited. AA29504 ([2-amino-4-(2,4,6-trimethylbenzylamino)-phenyl]-carbamic acid ethyl ester), an analog of K+ channel opener retigabine, acts as an agonist and a positive allosteric modulator (Ago-PAM) of δ-GABAARs. Based on electrophysiological studies using recombinant receptors, AA29504 was found to be a more potent and effective agonist in δ-GABAARs than in γ2-GABAARs. In comparison, AA29504 positively modulated the activity of recombinant δ-GABAARs more effectively than γ2-GABAARs, with no significant differences in potency. The impact of AA29504's efficacy- and potency-associated GABAAR subtype selectivity on radioligand binding properties remain unexplored. Using [3H]4'-ethynyl-4-n-propylbicycloorthobenzoate ([3H]EBOB) binding assay, we found no difference in the modulatory potency of AA29504 on GABA- and THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol)-induced responses between native forebrain GABAARs of wild type and δ knock-out mice. In recombinant receptors expressed in HEK293 cells, AA29504 showed higher efficacy on δ- than γ2-GABAARs in the GABA-independent displacement of [3H]EBOB binding. Interestingly, AA29504 showed a concentration-dependent stimulation of [3H]muscimol binding to γ2-GABAARs, which was absent in δ-GABAARs. This was explained by AA29504 shifting the low-affinity γ2-GABAAR towards a higher affinity desensitized state, thereby rising new sites capable of binding GABAAR agonists with low nanomolar affinity. Hence, the potential of AA29504 to act as a desensitization-modifying allosteric modulator of γ2-GABAARs deserves further investigation for its promising influence on shaping efficacy, duration and plasticity of GABAAR synaptic responses.
Collapse
Affiliation(s)
- Sylvia Sikstus
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20014, Turku, Finland
| | - Ali Y Benkherouf
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20014, Turku, Finland
| | - Sanna L Soini
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20014, Turku, Finland
| | - Mikko Uusi-Oukari
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20014, Turku, Finland.
| |
Collapse
|
11
|
Pence A, McGrath M, Lee SL, Raines DE. Pharmacological management of severe Cushing's syndrome: the role of etomidate. Ther Adv Endocrinol Metab 2022; 13:20420188211058583. [PMID: 35186251 PMCID: PMC8848075 DOI: 10.1177/20420188211058583] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/19/2021] [Indexed: 12/31/2022] Open
Abstract
Cushing's syndrome (CS) is an endocrine disease characterized by excessive adrenocortical steroid production. One of the mainstay pharmacological treatments for CS are steroidogenesis enzyme inhibitors, including the antifungal agent ketoconazole along with metyrapone, mitotane, and aminoglutethimide. Recently, osilodrostat was added to this drug class and approved by the US Food and Drug Administration (FDA) for the treatment of Cushing's Disease. Steroidogenesis enzyme inhibitors inhibit various enzymes along the cortisol biosynthetic pathway and may be used preoperatively to lower cortisol levels and reduce surgical risk associated with tumor resection or postoperatively when surgery and/or radiation therapies are not curative. Because their selectivities for steroidogenic enzymes vary, they may even be administered in combination to achieve relatively rapid control of severe hypercortisolemia. Unfortunately, all currently available inhibitors are accompanied by serious adverse side effects that limit dosing and often result in treatment failures. Although more commonly known as a general anesthetic induction agent, etomidate is another member of the steroidogenesis enzyme inhibitor drug class. It suppresses cortisol production primarily by inhibiting 11β-hydroxylase and is the only inhibitor that may be given parenterally. However, the sedative-hypnotic actions of etomidate limit its use as an acute management option for CS. Thus, some have recommended that it be used only in intensive care settings. In this review, we discuss the initial development of etomidate as an anesthetic agent, its subsequent development as a treatment for CS, and the recent advances in dosing and drug development that dissociate sedative-hypnotic and adrenostatic drug actions to facilitate CS treatment in non-critical care settings.
Collapse
Affiliation(s)
- Andrea Pence
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Megan McGrath
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Stephanie L. Lee
- Section of Endocrinology, Diabetes and Nutrition, Department of Medicine, Boston Medical Center, Boston, MA, USA
| | | |
Collapse
|
12
|
Ghit A, Assal D, Al-Shami AS, Hussein DEE. GABA A receptors: structure, function, pharmacology, and related disorders. J Genet Eng Biotechnol 2021; 19:123. [PMID: 34417930 PMCID: PMC8380214 DOI: 10.1186/s43141-021-00224-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/08/2021] [Indexed: 02/03/2023]
Abstract
Background γ-Aminobutyric acid sub-type A receptors (GABAARs) are the most prominent inhibitory neurotransmitter receptors in the CNS. They are a family of ligand-gated ion channel with significant physiological and therapeutic implications. Main body GABAARs are heteropentamers formed from a selection of 19 subunits: six α (alpha1-6), three β (beta1-3), three γ (gamma1-3), three ρ (rho1-3), and one each of the δ (delta), ε (epsilon), π (pi), and θ (theta) which result in the production of a considerable number of receptor isoforms. Each isoform exhibits distinct pharmacological and physiological properties. However, the majority of GABAARs are composed of two α subunits, two β subunits, and one γ subunit arranged as γ2β2α1β2α1 counterclockwise around the center. The mature receptor has a central chloride ion channel gated by GABA neurotransmitter and modulated by a variety of different drugs. Changes in GABA synthesis or release may have a significant effect on normal brain function. Furthermore, The molecular interactions and pharmacological effects caused by drugs are extremely complex. This is due to the structural heterogeneity of the receptors, and the existence of multiple allosteric binding sites as well as a wide range of ligands that can bind to them. Notably, dysfunction of the GABAergic system contributes to the development of several diseases. Therefore, understanding the relationship between GABAA receptor deficits and CNS disorders thus has a significant impact on the discovery of disease pathogenesis and drug development. Conclusion To date, few reviews have discussed GABAA receptors in detail. Accordingly, this review aims to summarize the current understanding of the structural, physiological, and pharmacological properties of GABAARs, as well as shedding light on the most common associated disorders.
Collapse
Affiliation(s)
- Amr Ghit
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy. .,Department of Biotechnology, Institute of Graduate Studies and Research (IGSR), Alexandria University, Alexandria, Egypt.
| | - Dina Assal
- Department of Biotechnology, American University in Cairo (AUC), Cairo, Egypt
| | - Ahmed S Al-Shami
- Department of Biotechnology, Institute of Graduate Studies and Research (IGSR), Alexandria University, Alexandria, Egypt.,Department of Zoology, Faculty of Science, Alexandria University, Alexandria, Egypt
| | - Diaa Eldin E Hussein
- Animal Health Research Institute (AHRI), Agricultural Research Center (ARC), Port of Alexandria, Alexandria, Egypt
| |
Collapse
|
13
|
Lahogue C, Pinault D. Frontoparietal anodal tDCS reduces ketamine-induced oscillopathies. Transl Neurosci 2021; 12:282-296. [PMID: 34239718 PMCID: PMC8240415 DOI: 10.1515/tnsci-2020-0157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/05/2021] [Accepted: 05/14/2021] [Indexed: 12/26/2022] Open
Abstract
During the prodromal phase of schizophrenia with its complex and insidious clinical picture, electroencephalographic recordings detect widespread oscillation disturbances (or oscillopathies) during the wake-sleep cycle. Neural oscillations are electrobiomarkers of the connectivity state within systems. A single-systemic administration of ketamine, a non-competitive NMDA glutamate receptor antagonist, transiently reproduces the oscillopathies with a clinical picture reminiscent of the psychosis prodrome. This acute pharmacological model may help the research and development of innovative treatments against psychotic transition. Transcranial electrical stimulation is recognized as an appropriate non-invasive therapeutic modality since it can increase cognitive performance and modulate neural oscillations with little or no side effects. Therefore, our objective was to set up, in the sedated adult rat, a stimulation method that is able to normalize ketamine-induced increase in gamma-frequency (30-80 Hz) oscillations and decrease in sigma-frequency (10-17 Hz) oscillations. Unilateral and bipolar frontoparietal (FP), transcranial anodal stimulation by direct current (<+1 mA) was applied in ketamine-treated rats. A concomitant bilateral electroencephalographic recording of the parietal cortex measured the stimulation effects on its spontaneously occurring oscillations. A 5 min FP anodal tDCS immediately and quickly reduced, significantly with an intensity-effect relationship, the ketamine-induced gamma hyperactivity, and sigma hypoactivity at least in the bilateral parietal cortex. A duration effect was also recorded. The tDCS also tended to diminish the ketamine-induced delta hypoactivity. These preliminary neurophysiological findings are promising for developing a therapeutic proof-of-concept against neuropsychiatric disorders.
Collapse
Affiliation(s)
- Caroline Lahogue
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie Cognitive et Physiopathologie de la Schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Centre de Recherche en Biomédecine de Strasbourg (CRBS), Faculté de médecine, Strasbourg, France
| | - Didier Pinault
- Université de Strasbourg, Strasbourg, France
- INSERM U1114, Neuropsychologie Cognitive et Physiopathologie de la Schizophrénie, Strasbourg, France
- Fédération de Médecine Translationnelle de Strasbourg (FMTS), Centre de Recherche en Biomédecine de Strasbourg (CRBS), Faculté de médecine, Strasbourg, France
| |
Collapse
|
14
|
Fantasia RJ, Nourmahnad A, Halpin E, Forman SA. Substituted Cysteine Modification and Protection with n-Alkyl- Methanethiosulfonate Reagents Yields a Precise Estimate of the Distance between Etomidate and a Residue in Activated GABA Type A Receptors. Mol Pharmacol 2021; 99:426-434. [PMID: 33766924 DOI: 10.1124/molpharm.120.000224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/10/2021] [Indexed: 11/22/2022] Open
Abstract
The anesthetic etomidate modulates synaptic α1β2/3γ2 GABAA receptors via binding sites located in transmembrane β+/α- interfaces. Various approaches indicate that etomidate binds near β2/3M286 side chains, including recent cryogenic electron microscopy images in α1β2γ2L receptors under nonphysiologic conditions with ∼3.5-Å resolution. We hypothesized that substituted cysteine modification and protection experiments using variably sized n-alkyl-methanethiosulfonate (MTS) reagents could precisely estimate the distance between bound etomidate and β3M286 side chains in activated functional receptors. Using voltage-clamp electrophysiology in Xenopus oocytes expressing α1β3M286Cγ2L GABAA receptors, we measured functional changes after exposing GABA-activated receptors to n-alkyl-MTS reagents, from methyl-MTS to n-decyl-MTS. Based on previous studies using a large sulfhydryl reagent, we anticipated that cysteine modifications large enough to overlap etomidate sites would cause persistently increased GABA sensitivity and decreased etomidate modulation and that etomidate would hinder these modifications, reducing effects. Based on altered GABA or etomidate sensitivity, ethyl-MTS and larger n-alkyl-MTS reagents modified GABA-activated α1β3M286Cγ2L GABAA receptors. Receptor modification by n-propyl-MTS or larger reagents caused persistently increased GABA sensitivity and decreased etomidate modulation. Receptor-bound etomidate blocked β3M286C modification by n-propyl-MTS, n-butyl-MTS, and n-hexyl-MTS. In contrast, GABA sensitivity was unaltered by receptor exposure to methyl-MTS or ethyl-MTS, and ethyl-MTS modification uniquely increased etomidate modulation. These results reveal a "cut-on" between ethyl-MTS and n-propyl-MTS, from which we infer that -S-(n-propyl) is the smallest β3M286C appendage that overlaps with etomidate sites. Molecular models of the native methionine and -S-ethyl and -S-(n-propyl) modified cysteines suggest that etomidate is located between 1.7 and 3.0 Å from the β3M286 side chain. SIGNIFICANCE STATEMENT: Precise spatial relationships between drugs and their receptor sites are essential for mechanistic understanding and drug development. This study combined electrophysiology, a cysteine substitution, and n-alkyl-methanethiosulfonate modifiers, creating a precise molecular ruler to estimate the distance between a α1β3γ2L GABA type A receptor residue and etomidate bound in the transmembrane β+/α- interface.
Collapse
Affiliation(s)
- Ryan J Fantasia
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Anahita Nourmahnad
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Elizabeth Halpin
- 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
| |
Collapse
|
15
|
Liang Z, Shang XB, Su J, Li GY, Fu FH, Guo JJ, Shan Y. Alternative Extraction Methods of Essential Oil From the Flowers of Citrus aurantium L. Var Daidai Tanaka: Evaluation of Oil Quality and Sedative-Hypnotic Activity. Nat Prod Commun 2021. [DOI: 10.1177/1934578x211004061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to analyze the content of hypnotic components in the essential oil from Citrus aurantium flowers (EDD), extracted by different methods, and to characterize its sedative-hypnotic effects. The sedative-hypnotic capacity of EDD was evaluated using pentobarbital-induced sleeping assays, locomotor activity tests and GABAA receptor antagonists. The results showed that EDD extracted by steam and water distillation (SWD), hydrodistillation (HD), and ultrasound-assisted hydrodistillation (UHD) had as their main components linalool, linalyl acetate, and limonene, comprising more than 55% of the total peak area. Compared with EDD extracted by HD and UHD, the total content of linalool and linalyl acetate in EDD obtained by SWD was highest, whereas the content of limonene in EDD extracted by the 3 different methods was not different. Oral and intraperitoneal administration of EDD resulted in reduced sleep latency and increased sleep duration of mice, as well as reduced locomotor activity, which was proven by decreases in the total distance travelled, average velocity, number of activities, and central distance. Interestingly, intraperitoneal injection of EDD had better sedative and hypnotic effects than oral ingestion. In vitro assays using SH-SY5Y cells showed that EDD dose-dependently increased Cl− influx, which could be blocked by the GABAA receptor antagonists, picrotoxin, bicuculline, and flumazenil, suggesting that EDD promoted sedative-hypnotic activity by potentiating GABAA receptor-mediated Cl− current responses. Altogether, these results suggest that the important hypnotic-sedative activity of EDD appears to be due to the effects of limonene, and particularly the high contents of linalool and linalyl acetate, which were effectively extracted by SWD.
Collapse
Affiliation(s)
- Zengenni Liang
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Xue-bo Shang
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Jin Su
- Longping Branch Graduate School, Hunan University, Changsha, China
| | - Gao-yang Li
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Fu-hua Fu
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Jia-jing Guo
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Yang Shan
- Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| |
Collapse
|
16
|
Sorrenti V, Cecchetto C, Maschietto M, Fortinguerra S, Buriani A, Vassanelli S. Understanding the Effects of Anesthesia on Cortical Electrophysiological Recordings: A Scoping Review. Int J Mol Sci 2021; 22:1286. [PMID: 33525470 PMCID: PMC7865872 DOI: 10.3390/ijms22031286] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/21/2021] [Accepted: 01/25/2021] [Indexed: 12/28/2022] Open
Abstract
General anesthesia in animal experiments is an ethical must and is required for all the procedures that are likely to cause more than slight or momentary pain. As anesthetics are known to deeply affect experimental findings, including electrophysiological recordings of brain activity, understanding their mechanism of action is of paramount importance. It is widely recognized that the depth and type of anesthesia introduce significant bias in electrophysiological measurements by affecting the shape of both spontaneous and evoked signals, e.g., modifying their latency and relative amplitude. Therefore, for a given experimental protocol, it is relevant to identify the appropriate anesthetic, to minimize the impact on neuronal circuits and related signals under investigation. This review focuses on the effect of different anesthetics on cortical electrical recordings, examining their molecular mechanisms of action, their influence on neuronal microcircuits and, consequently, their impact on cortical measurements.
Collapse
Affiliation(s)
- Vincenzo Sorrenti
- Department of Pharmaceutical & Pharmacological Sciences, University of Padova, 35131 Padova, Italy
- Maria Paola Belloni Center for Personalized Medicine, Data Medica Group (Synlab Limited), 35100 Padova, Italy;
| | - Claudia Cecchetto
- Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan;
- Department of Biomedical Sciences, Section of Physiology, University of Padova, via F. Marzolo 3, 35131 Padova, Italy;
- Padua Neuroscience Center, University of Padova, via Orus 2/B, 35131 Padova, Italy
| | - Marta Maschietto
- Department of Biomedical Sciences, Section of Physiology, University of Padova, via F. Marzolo 3, 35131 Padova, Italy;
| | | | - Alessandro Buriani
- Maria Paola Belloni Center for Personalized Medicine, Data Medica Group (Synlab Limited), 35100 Padova, Italy;
| | - Stefano Vassanelli
- Department of Biomedical Sciences, Section of Physiology, University of Padova, via F. Marzolo 3, 35131 Padova, Italy;
- Padua Neuroscience Center, University of Padova, via Orus 2/B, 35131 Padova, Italy
| |
Collapse
|
17
|
Zhang X, Baer AG, Price JM, Jones PC, Garcia BJ, Romero J, Cliff AM, Mi W, Brown JB, Jacobson DA, Lydic R, Baghdoyan HA. Neurotransmitter networks in mouse prefrontal cortex are reconfigured by isoflurane anesthesia. J Neurophysiol 2020; 123:2285-2296. [PMID: 32347157 PMCID: PMC7311717 DOI: 10.1152/jn.00092.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This study quantified eight small-molecule neurotransmitters collected simultaneously from prefrontal cortex of C57BL/6J mice (n = 23) during wakefulness and during isoflurane anesthesia (1.3%). Using isoflurane anesthesia as an independent variable enabled evaluation of the hypothesis that isoflurane anesthesia differentially alters concentrations of multiple neurotransmitters and their interactions. Machine learning was applied to reveal higher order interactions among neurotransmitters. Using a between-subjects design, microdialysis was performed during wakefulness and during anesthesia. Concentrations (nM) of acetylcholine, adenosine, dopamine, GABA, glutamate, histamine, norepinephrine, and serotonin in the dialysis samples are reported (means ± SD). Relative to wakefulness, acetylcholine concentration was lower during isoflurane anesthesia (1.254 ± 1.118 vs. 0.401 ± 0.134, P = 0.009), and concentrations of adenosine (29.456 ± 29.756 vs. 101.321 ± 38.603, P < 0.001), dopamine (0.0578 ± 0.0384 vs. 0.113 ± 0.084, P = 0.036), and norepinephrine (0.126 ± 0.080 vs. 0.219 ± 0.066, P = 0.010) were higher during anesthesia. Isoflurane reconfigured neurotransmitter interactions in prefrontal cortex, and the state of isoflurane anesthesia was reliably predicted by prefrontal cortex concentrations of adenosine, norepinephrine, and acetylcholine. A novel finding to emerge from machine learning analyses is that neurotransmitter concentration profiles in mouse prefrontal cortex undergo functional reconfiguration during isoflurane anesthesia. Adenosine, norepinephrine, and acetylcholine showed high feature importance, supporting the interpretation that interactions among these three transmitters may play a key role in modulating levels of cortical and behavioral arousal. NEW & NOTEWORTHY This study discovered that interactions between neurotransmitters in mouse prefrontal cortex were altered during isoflurane anesthesia relative to wakefulness. Machine learning further demonstrated that, relative to wakefulness, higher order interactions among neurotransmitters were disrupted during isoflurane administration. These findings extend to the neurochemical domain the concept that anesthetic-induced loss of wakefulness results from a disruption of neural network connectivity.
Collapse
Affiliation(s)
- Xiaoying Zhang
- Department of Anesthesiology, University of Tennessee Medical Center, Knoxville, Tennessee.,Department of Psychology, University of Tennessee, Knoxville, Tennessee.,Anesthesia and Operation Center, Chinese PLA General Hospital, Beijing, China
| | - Aaron G Baer
- Department of Anesthesiology, University of Tennessee Medical Center, Knoxville, Tennessee
| | - Joshua M Price
- Office of Information Technology, University of Tennessee, Knoxville, Tennessee
| | - Piet C Jones
- Oak Ridge National Laboratory, Oak Ridge, Tennessee.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee
| | | | - Jonathon Romero
- Oak Ridge National Laboratory, Oak Ridge, Tennessee.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee
| | - Ashley M Cliff
- Oak Ridge National Laboratory, Oak Ridge, Tennessee.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee
| | - Weidong Mi
- Anesthesia and Operation Center, Chinese PLA General Hospital, Beijing, China
| | - James B Brown
- Molecular Ecosystems Biology Department, Lawrence Berkeley National Laboratory, Berkeley, California
| | | | - Ralph Lydic
- Department of Anesthesiology, University of Tennessee Medical Center, Knoxville, Tennessee.,Department of Psychology, University of Tennessee, Knoxville, Tennessee.,Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Helen A Baghdoyan
- Department of Anesthesiology, University of Tennessee Medical Center, Knoxville, Tennessee.,Department of Psychology, University of Tennessee, Knoxville, Tennessee.,Oak Ridge National Laboratory, Oak Ridge, Tennessee
| |
Collapse
|
18
|
SU X, ZHU W, TIAN Y, TAN L, WU H, WU L. Regulatory Effects of Propofol on High-Dose Remifentanil-Induced Hyperalgesia. Physiol Res 2020; 69:157-164. [PMID: 31852207 DOI: 10.33549/physiolres.934133] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We aimed to evaluate the regulatory effects of propofol on high-dose remifentanil-induced hyperalgesia. A total of 180 patients receiving laparoscopic cholecystectomy were randomly divided into sevoflurane + high-dose remifentanil (SH) group, sevoflurane + low-dose remifentanil (SL) group and propofol + high-dose remifentanil group (PH) group (n=60). After intravenous administration of midazolam, SH and SL groups were induced with sevoflurane and remifentanil, and PH group was induced with propofol and remifentanil. During anesthesia maintenance, SH and SL groups were given 0.3 μg/kg/min and 0.1 μg/kg/min sevoflurane and remifentanil respectively, and PH group was given 0.3 μg/kg/min propofol and remifentanil. The three groups had significantly different awakening time, extubation time and total dose of remifentanil (P<0.001). Compared with SL group, periumbilical mechanical pain thresholds 6 h and 24 h after surgery significantly decreased in SH group (P<0.05), and the visual analog scale (VAS) scores significantly increased 30 min, 2 h and 6 h after surgery (P<0.05). Compared with SH group, periumbilical mechanical thresholds 6 h and 24 h after surgery were significantly higher in PH group (P<0.05), and VAS scores 30 min, 2 h and 6 h after surgery were significantly lower (P<0.05). PH group first used patient-controlled intravenous analgesia pump significantly later than SL group did (P<0.05). The total consumptions of sufentanil in PH and SL groups were significantly lower than that of SH group (P<0.05). The incidence rates of bradycardia and postoperative chill in PH and SH groups were significantly higher than those of SL group (P<0.05). Anesthesia by infusion of high-dose remifentanil plus sevoflurane caused postoperative hyperalgesia which was relieved through intravenous anesthesia with propofol.
Collapse
Affiliation(s)
- X. SU
- Department of Anesthesiology, Suqian First Hospital, Suqian, Jiangsu Province, P. R. China
| | - W. ZHU
- Department of Anesthesiology, Jiangsu Province Hospital, Nanjing, Jiangsu Province, P. R. China
| | - Y. TIAN
- Department of Anesthesiology, Suqian First Hospital, Suqian, Jiangsu Province, P. R. China
| | - L. TAN
- Department of Anesthesiology, Suqian First Hospital, Suqian, Jiangsu Province, P. R. China
| | - H. WU
- Department of Anesthesiology, Suqian First Hospital, Suqian, Jiangsu Province, P. R. China
| | - L. WU
- Department of Anesthesiology, Suqian First Hospital, Suqian, Jiangsu Province, P. R. China
| |
Collapse
|
19
|
Sills GJ, Rogawski MA. Mechanisms of action of currently used antiseizure drugs. Neuropharmacology 2020; 168:107966. [PMID: 32120063 DOI: 10.1016/j.neuropharm.2020.107966] [Citation(s) in RCA: 228] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/09/2020] [Accepted: 01/12/2020] [Indexed: 02/08/2023]
Abstract
Antiseizure drugs (ASDs) prevent the occurrence of seizures; there is no evidence that they have disease-modifying properties. In the more than 160 years that orally administered ASDs have been available for epilepsy therapy, most agents entering clinical practice were either discovered serendipitously or with the use of animal seizure models. The ASDs originating from these approaches act on brain excitability mechanisms to interfere with the generation and spread of epileptic hyperexcitability, but they do not address the specific defects that are pathogenic in the epilepsies for which they are prescribed, which in most cases are not well understood. There are four broad classes of such ASD mechanisms: (1) modulation of voltage-gated sodium channels (e.g. phenytoin, carbamazepine, lamotrigine), voltage-gated calcium channels (e.g. ethosuximide), and voltage-gated potassium channels [e.g. retigabine (ezogabine)]; (2) enhancement of GABA-mediated inhibitory neurotransmission (e.g. benzodiazepines, tiagabine, vigabatrin); (3) attenuation of glutamate-mediated excitatory neurotransmission (e.g. perampanel); and (4) modulation of neurotransmitter release via a presynaptic action (e.g. levetiracetam, brivaracetam, gabapentin, pregabalin). In the past two decades there has been great progress in identifying the pathophysiological mechanisms of many genetic epilepsies. Given this new understanding, attempts are being made to engineer specific small molecule, antisense and gene therapies that functionally reverse or structurally correct pathogenic defects in epilepsy syndromes. In the near future, these new therapies will begin a paradigm shift in the treatment of some rare genetic epilepsy syndromes, but targeted therapies will remain elusive for the vast majority of epilepsies until their causes are identified. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
Collapse
Affiliation(s)
- Graeme J Sills
- School of Life Sciences, University of Glasgow, Glasgow, UK.
| | - Michael A Rogawski
- Department of Neurology, School of Medicine, University of California, Davis, Sacramento, CA, USA; Department of Pharmacology, School of Medicine, University of California, Davis, Sacramento, CA, USA
| |
Collapse
|
20
|
GABA A Receptor Ligands Often Interact with Binding Sites in the Transmembrane Domain and in the Extracellular Domain-Can the Promiscuity Code Be Cracked? Int J Mol Sci 2020; 21:ijms21010334. [PMID: 31947863 PMCID: PMC6982053 DOI: 10.3390/ijms21010334] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/20/2019] [Accepted: 12/26/2019] [Indexed: 01/06/2023] Open
Abstract
Many allosteric binding sites that modulate gamma aminobutyric acid (GABA) effects have been described in heteropentameric GABA type A (GABAA) receptors, among them sites for benzodiazepines, pyrazoloquinolinones and etomidate. Diazepam not only binds at the high affinity extracellular “canonical” site, but also at sites in the transmembrane domain. Many ligands of the benzodiazepine binding site interact also with homologous sites in the extracellular domain, among them the pyrazoloquinolinones that exert modulation at extracellular α+/β− sites. Additional interaction of this chemotype with the sites for etomidate has also been described. We have recently described a new indole-based scaffold with pharmacophore features highly similar to pyrazoloquinolinones as a novel class of GABAA receptor modulators. Contrary to what the pharmacophore overlap suggests, the ligand presented here behaves very differently from the identically substituted pyrazoloquinolinone. Structural evidence demonstrates that small changes in pharmacophore features can induce radical changes in ligand binding properties. Analysis of published data reveals that many chemotypes display a strong tendency to interact promiscuously with binding sites in the transmembrane domain and others in the extracellular domain of the same receptor. Further structural investigations of this phenomenon should enable a more targeted path to less promiscuous ligands, potentially reducing side effect liabilities.
Collapse
|
21
|
Cardioprotection by Humoral Factors Released After Remote Ischemic Preconditioning Depends on Anesthetic Regimen. Crit Care Med 2020; 47:e250-e255. [PMID: 30608281 DOI: 10.1097/ccm.0000000000003629] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES Remote ischemic preconditioning (RIPC) is a practicable and noninvasive method to protect the heart against ischemia reperfusion injury. Unfortunately results from clinical studies are not convincing. Propofol is suggested to be an inhibiting factor of cardioprotection by RIPC, but the underlying mechanism is still unknown. We investigated whether after RIPC the release of humoral factors and/or the direct cardioprotective effect at the myocardium is inhibited by propofol. DESIGN Randomized, prospective, blinded laboratory investigation. SETTING Experimental laboratory. PATIENTS/SUBJECTS Male Wistar rats. INTERVENTIONS Repetitive hind limb ischemia in rats-blood plasma transfers to isolated rat heart. MEASUREMENTS AND MAIN RESULTS In male Wistar rats (six groups, each n = 6/group), RIPC was induced by four cycles of 5 minutes bilateral hind limb ischemia alternately with 5 minutes of reperfusion. Blood samples were taken with (RIPC) and without RIPC (Con). Rats received continuous anesthesia with pentobarbital (Pento, 40 mg/kg body weight/hr) or propofol (Prop, 12 mg/kg body weight/hr), respectively. Cardioprotective properties of the blood plasma was investigated in the rat heart in vitro (six groups, each n = 6/group) perfused with Krebs-Henseleit buffer alone or with propofol (10 µM). Plasma was administered over 10 minutes before myocardial ischemia. All hearts underwent 33 minutes of global ischemia followed by 1 hour of reperfusion. At the end of the experiments, infarct size was determined by triphenyl-tetrazolium-chloride staining. RIPC plasma from pentobarbital anesthetized rats (Pento-RIPC) reduced infarct size from 64% (62-71%) (Pento-Con) to 34% (30-39%) (p < 0.0001). Infarct size with control plasma from propofol anesthetized rats was 59% (58-64%) (Prop-Con). RIPC plasma could not induce cardioprotection (Prop-RIPC: 63% [56-70%] ns vs Prop-Con). In contrast, RIPC plasma from pentobarbital anesthetized rats induced a significant infarct size reduction under propofol perfusion (Pento-RIPC: 34% [30-42%] vs Pento-Con: 54% [53-63%]; p < 0.0001). CONCLUSIONS Loss of cardioprotection by RIPC during propofol anesthesia depends on inhibition of release of humoral factors.
Collapse
|
22
|
Cao Y, Yan H, Yu G, Su R. Flumazenil-insensitive benzodiazepine binding sites in GABAA receptors contribute to benzodiazepine-induced immobility in zebrafish larvae. Life Sci 2019; 239:117033. [DOI: 10.1016/j.lfs.2019.117033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/16/2019] [Accepted: 10/28/2019] [Indexed: 10/25/2022]
|
23
|
Propofol weakens hypoxia-aroused apoptosis and autophagy via elevating microRNA-137 in neurocytes. Exp Mol Pathol 2019; 112:104327. [PMID: 31678238 DOI: 10.1016/j.yexmp.2019.104327] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Hypoxia was proven to cause brain cell apoptosis and autophagy. Herein, we tested the influences of propofol, a commonly used intravenous sedative hypnotic drug, on apoptosis and autophagy aroused by hypoxia stimulation in PC-12 and HT-22 cells. METHODS Followed by hypoxia and/or propofol treatment, cell viability of PC-12 and HT-22 cells, apoptosis and autophagy, along with microRNA-137 (miR-137) expression were measured, respectively. Then, miR-137 inhibitor was transfected to silence miR-137. Whether miR-137 took part in the impacts of propofol on hypoxia-exposed cells was explored. Finally, the activities of PI3K/AKT/mTOR and ERK pathways were measured. RESULTS Hypoxia stimulation aroused cell apoptosis and elevated cell autophagy in PC-12 and HT-22 cells. Propofol weakened the apoptosis and autophagy of PC-12 and HT-22 cells aroused by hypoxia. Moreover, propofol elevated the miR-137 level in PC-12 and HT-22 cells. Silencing miR-137 declined the influences of propofol on hypoxia-induced injuries. Besides, propofol promoted PI3K/AKT/mTOR and ERK pathways activation in hypoxia-exposed cells through raising miR-137. CONCLUSION Propofol weakened hypoxia-aroused apoptosis and autophagy of PC-12 and HT-22 cells might be through raising miR-137 level and thereby promoting PI3K/AKT/mTOR and ERK pathways activation.
Collapse
|
24
|
|
25
|
Jayakar SS, Zhou X, Chiara DC, Jarava-Barrera C, Savechenkov PY, Bruzik KS, Tortosa M, Miller KW, Cohen JB. Identifying Drugs that Bind Selectively to Intersubunit General Anesthetic Sites in the α1 β3 γ2 GABA AR Transmembrane Domain. Mol Pharmacol 2019; 95:615-628. [PMID: 30952799 DOI: 10.1124/mol.118.114975] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 03/29/2019] [Indexed: 12/19/2022] Open
Abstract
GABAA receptors (GABAARs) are targets for important classes of clinical agents (e.g., anxiolytics, anticonvulsants, and general anesthetics) that act as positive allosteric modulators (PAMs). Previously, using photoreactive analogs of etomidate ([3H]azietomidate) and mephobarbital [[3H]1-methyl-5-allyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid ([3H]R-mTFD-MPAB)], we identified two homologous but pharmacologically distinct classes of general anesthetic binding sites in the α1β3γ2 GABAAR transmembrane domain at β +-α - (β + sites) and α +-β -/γ +-β - (β - sites) subunit interfaces. We now use competition photolabeling with [3H]azietomidate and [3H]R-mTFD-MPAB to identify para-substituted propofol analogs and other drugs that bind selectively to intersubunit anesthetic sites. Propofol and 4-chloro-propofol bind with 5-fold selectivity to β +, while derivatives with bulkier lipophilic substitutions [4-(tert-butyl)-propofol and 4-(hydroxyl(phenyl)methyl)-propofol] bind with ∼10-fold higher affinity to β - sites. Similar to R-mTFD-MPAB and propofol, these drugs bind in the presence of GABA with similar affinity to the α +-β - and γ +-β - sites. However, we discovered four compounds that bind with different affinities to the two β - interface sites. Two of these bind with higher affinity to one of the β - sites than to the β + sites. We deduce that 4-benzoyl-propofol binds with >100-fold higher affinity to the γ +-β - site than to the α +-β - or β +-α - sites, whereas loreclezole, an anticonvulsant, binds with 5- and 100-fold higher affinity to the α +-β - site than to the β + and γ +-β - sites. These studies provide a first identification of PAMs that bind selectively to a single intersubunit site in the GABAAR transmembrane domain, a property that may facilitate the development of subtype selective GABAAR PAMs.
Collapse
Affiliation(s)
- Selwyn S Jayakar
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Xiaojuan Zhou
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - David C Chiara
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Carlos Jarava-Barrera
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Pavel Y Savechenkov
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Karol S Bruzik
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Mariola Tortosa
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Keith W Miller
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| | - Jonathan B Cohen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (S.S.J., D.C.C., J.B.C.); Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (X.Z., K.W.M.); Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois (P.Y.S., K.S.B.); and the Departamento de Quimica Orgánica, Universidad Autónoma de Madrid, Madrid, Spain (C.J.-B., M.T.)
| |
Collapse
|
26
|
Toossi A, Everaert DG, Uwiera RRE, Hu DS, Robinson K, Gragasin FS, Mushahwar VK. Effect of anesthesia on motor responses evoked by spinal neural prostheses during intraoperative procedures. J Neural Eng 2019; 16:036003. [PMID: 30790787 DOI: 10.1088/1741-2552/ab0938] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE The overall goal of this study was to investigate the effects of various anesthetic protocols on the intraoperative responses to intraspinal microstimulation (ISMS). ISMS is a neuroprosthetic approach that targets the motor networks in the ventral horns of the spinal cord to restore function after spinal cord injury. In preclinical studies, ISMS in the lumbosacral enlargement produced standing and walking by activating networks controlling the hindlimb muscles. ISMS implants are placed surgically under anesthesia, and refinements in placement are made based on the evoked responses. Anesthesia can have a significant effect on the responses evoked by spinal neuroprostheses; therefore, in preparation for clinical testing of ISMS, we compared the evoked responses under a common clinical neurosurgical anesthetic protocol with those evoked under protocols commonly used in preclinical studies. APPROACH Experiments were conducted in seven pigs. An ISMS microelectrode array was implanted in the lumbar enlargement and responses to ISMS were measured under three anesthetic protocols: (1) isoflurane, an agent used pre-clinically and clinically, (2) total intravenous anesthesia (TIVA) with propofol as the main agent commonly used in clinical neurosurgical procedures, (3) TIVA with sodium pentobarbital, an anesthetic agent used mostly preclinically. Responses to ISMS were evaluated based on stimulation thresholds, movement kinematics, and joint torques. Motor evoked potentials (MEP) and plasma concentrations of propofol were also measured. MAIN RESULTS ISMS under propofol anesthesia produced large and functional responses that were not statistically different from those produced under pentobarbital anesthesia. Isoflurane, however, significantly suppressed the ISMS-evoked responses. SIGNIFICANCE This study demonstrated that the choice of anesthesia is critical for intraoperative assessments of motor responses evoked by spinal neuroprostheses. Propofol and pentobarbital anesthesia did not overly suppress the effects of ISMS; therefore, propofol is expected to be a suitable anesthetic agent for clinical intraoperative testing of an intraspinal neuroprosthetic system.
Collapse
Affiliation(s)
- Amirali Toossi
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada. Sensory Motor Adaptive Rehabilitative Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
| | | | | | | | | | | | | |
Collapse
|
27
|
Szabo A, Nourmahnad A, Halpin E, Forman SA. Monod-Wyman-Changeux Allosteric Shift Analysis in Mutant α1 β3 γ2L GABA A Receptors Indicates Selectivity and Crosstalk among Intersubunit Transmembrane Anesthetic Sites. Mol Pharmacol 2019; 95:408-417. [PMID: 30696720 DOI: 10.1124/mol.118.115048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/19/2019] [Indexed: 12/28/2022] Open
Abstract
Propofol, etomidate, and barbiturate anesthetics are allosteric coagonists at pentameric α1β3γ2 GABAA receptors, modulating channel activation via four biochemically established intersubunit transmembrane pockets. Etomidate selectively occupies the two β +/α - pockets, the barbiturate photolabel R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB) occupies homologous α +/β - and γ +/β - pockets, and propofol occupies all four. Functional studies of mutations at M2-15' or M3-36' loci abutting these pockets provide conflicting results regarding their relative contributions to propofol modulation. We electrophysiologically measured GABA-dependent channel activation in α1β3γ2L or receptors with single M2-15' (α1S270I, β3N265M, and γ2S280W) or M3-36' (α1A291W, β3M286W, and γ2S301W) mutations, in the absence and presence of equipotent clinical range concentrations of etomidate, R-mTFD-MPAB, and propofol. Estimated open probabilities were calculated and analyzed using global two-state Monod-Wyman-Changeux models to derive log(d) parameters proportional to anesthetic-induced channel modulating energies (where d is the allosteric anesthetic shift factor). All mutations reduced the log(d) values for anesthetics occupying both abutting and nonabutting pockets. The Δlog(d) values [log(d, mutant) - log(d, wild type)] for M2-15' mutations abutting an anesthetic's biochemically established binding sites were consistently larger than the Δlog(d) values for nonabutting mutations, although this was not true for the M3-36' mutant Δlog(d) values. The sums of the anesthetic-associated Δlog(d) values for sets of M2-15' or M3-36' mutations were all much larger than the wild-type log(d) values. Mutant Δlog(d) values qualitatively reflect anesthetic site occupancy patterns. However, the lack of Δlog(d) additivity undermines quantitative comparisons of distinct site contributions to anesthetic modulation because the mutations impaired both abutting anesthetic binding effects and positive cooperativity between anesthetic binding sites.
Collapse
Affiliation(s)
- Andrea Szabo
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Anahita Nourmahnad
- Beecher-Mallinckrodt Laboratories, Department of Anesthesia Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Elizabeth Halpin
- 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
| |
Collapse
|
28
|
Shin DJ, Germann AL, Covey DF, Steinbach JH, Akk G. Analysis of GABA A Receptor Activation by Combinations of Agonists Acting at the Same or Distinct Binding Sites. Mol Pharmacol 2018; 95:70-81. [PMID: 30337372 DOI: 10.1124/mol.118.113464] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/17/2018] [Indexed: 11/22/2022] Open
Abstract
Under both physiologic and clinical conditions GABAA receptors are exposed to multiple agonists, including the transmitter GABA, endogenous or exogenous neuroactive steroids, and various GABAergic anesthetic and sedative drugs. The functional output of the receptor reflects the interplay among all active agents. We have investigated the activation of the concatemeric α1β2γ2L GABAA receptor by combinations of agonists. Simulations of receptor activity using the coagonist concerted transition model demonstrate that the response amplitude in the presence of agonist combinations is highly dependent on whether the paired agonists interact with the same or distinct sites. The experimental data for receptor activation by agonist combinations were in agreement with the established views of the overlap of binding sites for several pairs of orthosteric (GABA, β-alanine, and piperidine-4-sulfonic acid) and/or allosteric agents (propofol, pentobarbital, and several neuroactive steroids). Conversely, the degree of potentiation when two GABAergic agents are coapplied can be used to determine whether the compounds act by binding to the same or distinct sites. We show that common interaction sites mediate the actions of 5α- and 5β-reduced neuroactive steroids, and natural and enantiomeric steroids. Furthermore, the results indicate that the anesthetics propofol and pentobarbital interact with partially shared binding sites. We propose that the findings may be used to predict the efficacy of drug mixtures in combination therapy and thus have potential clinical relevance.
Collapse
Affiliation(s)
- Daniel J Shin
- Departments of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.) and Developmental Biology (D.F.C.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Allison L Germann
- Departments of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.) and Developmental Biology (D.F.C.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Douglas F Covey
- Departments of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.) and Developmental Biology (D.F.C.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Joe Henry Steinbach
- Departments of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.) and Developmental Biology (D.F.C.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Departments of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.) and Developmental Biology (D.F.C.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| |
Collapse
|
29
|
Alphaxalone Binds in Inner Transmembrane β+-α- Interfaces of α1β3γ2 γ-Aminobutyric Acid Type A Receptors. Anesthesiology 2018; 128:338-351. [PMID: 29210709 DOI: 10.1097/aln.0000000000001978] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Neurosteroids like alphaxalone are potent anxiolytics, anticonvulsants, amnestics, and sedative-hypnotics, with effects linked to enhancement of γ-aminobutyric acid type A (GABAA) receptor gating in the central nervous system. Data locating neurosteroid binding sites on synaptic αβγ GABAA receptors are sparse and inconsistent. Some evidence points to outer transmembrane β-α interfacial pockets, near sites that bind the anesthetics etomidate and propofol. Other evidence suggests that steroids bind more intracellularly in β-α interfaces. METHODS The authors created 12 single-residue β3 cysteine mutations: β3T262C and β3T266C in β3-M2; and β3M283C, β3Y284C, β3M286C, β3G287C, β3F289C, β3V290C, β3F293C, β3L297C, β3E298C, and β3F301C in β3-M3 helices. The authors coexpressed α1 and γ2L with each mutant β3 subunit in Xenopus oocytes and electrophysiologically tested each mutant for covalent sulfhydryl modification by the water-soluble reagent para-chloromercuribenzenesulfonate. Then, the authors assessed whether receptor-bound alphaxalone, etomidate, or propofol blocked cysteine modification, implying steric hindrance. RESULTS Eleven mutant β3 subunits, when coexpressed with α1 and γ2L, formed functional channels that displayed varied sensitivities to the three anesthetics. Exposure to para-chloromercuribenzenesulfonate produced irreversible functional changes in ten mutant receptors. Protection by alphaxalone was observed in receptors with β3V290C, β3F293C, β3L297C, or β3F301C mutations. Both etomidate and propofol protected receptors with β3M286C or β3V290C mutations. Etomidate also protected β3F289C. In α1β3γ2L structural homology models, all these protected residues are located in transmembrane β-α interfaces. CONCLUSIONS Alphaxalone binds in transmembrane β-α pockets of synaptic GABAA receptors that are adjacent and intracellular to sites for the potent anesthetics etomidate and propofol.
Collapse
|
30
|
Olsen RW. GABA A receptor: Positive and negative allosteric modulators. Neuropharmacology 2018; 136:10-22. [PMID: 29407219 PMCID: PMC6027637 DOI: 10.1016/j.neuropharm.2018.01.036] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 12/11/2022]
Abstract
gamma-Aminobutyric acid (GABA)-mediated inhibitory neurotransmission and the gene products involved were discovered during the mid-twentieth century. Historically, myriad existing nervous system drugs act as positive and negative allosteric modulators of these proteins, making GABA a major component of modern neuropharmacology, and suggesting that many potential drugs will be found that share these targets. Although some of these drugs act on proteins involved in synthesis, degradation, and membrane transport of GABA, the GABA receptors Type A (GABAAR) and Type B (GABABR) are the targets of the great majority of GABAergic drugs. This discovery is due in no small part to Professor Norman Bowery. Whereas the topic of GABABR is appropriately emphasized in this special issue, Norman Bowery also made many insights into GABAAR pharmacology, the topic of this article. GABAAR are members of the ligand-gated ion channel receptor superfamily, a chloride channel family of a dozen or more heteropentameric subtypes containing 19 possible different subunits. These subtypes show different brain regional and subcellular localization, age-dependent expression, and potential for plastic changes with experience including drug exposure. Not only are GABAAR the targets of agonist depressants and antagonist convulsants, but most GABAAR drugs act at other (allosteric) binding sites on the GABAAR proteins. Some anxiolytic and sedative drugs, like benzodiazepine and related drugs, act on GABAAR subtype-dependent extracellular domain sites. General anesthetics including alcohols and neurosteroids act at GABAAR subunit-interface trans-membrane sites. Ethanol at high anesthetic doses acts on GABAAR subtype-dependent trans-membrane domain sites. Ethanol at low intoxicating doses acts at GABAAR subtype-dependent extracellular domain sites. Thus GABAAR subtypes possess pharmacologically specific receptor binding sites for a large group of different chemical classes of clinically important neuropharmacological agents. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
Collapse
Affiliation(s)
- Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| |
Collapse
|
31
|
Delineation of the functional properties and the mechanism of action of AA29504, an allosteric agonist and positive allosteric modulator of GABA A receptors. Biochem Pharmacol 2018; 150:305-319. [DOI: 10.1016/j.bcp.2018.02.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/13/2018] [Indexed: 11/22/2022]
|
32
|
Forman SA. Combining Mutations and Electrophysiology to Map Anesthetic Sites on Ligand-Gated Ion Channels. Methods Enzymol 2018; 602:369-389. [PMID: 29588039 DOI: 10.1016/bs.mie.2018.01.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
General anesthetics are known to act in part by binding to and altering the function of pentameric ligand-gated ion channels such as nicotinic acetylcholine and γ-aminobutyric acid type A receptors. Combining heterologous expression of the subunits that assemble to form these ion channels, mutagenesis techniques and voltage-clamp electrophysiology have enabled a variety of "structure-function" approaches to questions of where anesthetic binds to these ion channels and how they enhance or inhibit channel function. Here, we review the evolution of concepts and experimental strategies during the last three decades, since molecular biological and electrophysiological tools became widely used. Topics covered include: (1) structural models as interpretive frameworks, (2) various electrophysiological approaches and their limitations, (3) Monod-Wyman-Changeux allosteric models as functional frameworks, (4) structural strategies including chimeras and point mutations, and (5) methods based on cysteine substitution and covalent modification. We discuss in particular depth the experimental design considerations for substituted cysteine modification-protection studies.
Collapse
Affiliation(s)
- Stuart A Forman
- Massachusetts General Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States.
| |
Collapse
|
33
|
Deng F, Ouyang M, Wang X, Yao X, Chen Y, Tao T, Sun X, Xu L, Tang J, Zhao L. Differential role of intravenous anesthetics in colorectal cancer progression: implications for clinical application. Oncotarget 2018; 7:77087-77095. [PMID: 27780923 PMCID: PMC5363570 DOI: 10.18632/oncotarget.12800] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 10/17/2016] [Indexed: 01/05/2023] Open
Abstract
Anesthetics are unavoidable to colorectal cancer (CRC) patients who underwent surgical treatment. Thus, the molecular mechanisms underlying the role of the intravenous anesthetics in CRC metastasis are still unclear. In this study, the effects of intravenous anesthetics, such as propofol, etomidate and dexmedetomidine, on cell migration were determined. The migration of CRC cells was inhibited by propofol in vitro, but not in vivo. Etomidate, however, promoted the migration of CRC cells both in vitro and in vivo. Epithelial-mesenchymal transition (EMT) mediated the promotive effect of propofol and etomidate on the migration of CRC cells through PI3K/AKT signaling pathway. Dexmedetomidine alone or in combination with propofol or etomidate had minor effect on the migration of CRC cells. These findings indicate that propofol inhibites CRC cell migration in vitro. Etomidate playes a role for prompting CRC metastasis progression by activating (PI3K)/AKT signaling and inducing EMT. It provides an important hint for the clinical application of these anesthetics.
Collapse
Affiliation(s)
- Fengliu Deng
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.,Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Mingwen Ouyang
- Department of anesthesia, Fifth Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong, China
| | - Xiaofei Wang
- Department of Anesthesia, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Xueqing Yao
- Department of General Surgery, Guangdong General Hospital, Guangdong Academy of Medical Science, Guangzhou, Guangdong, China
| | - Yeming Chen
- Department of Anesthesia, Huarui Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Tao Tao
- Department of Anesthesia, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Xuegang Sun
- The Key Laboratory of Molecular Biology, State Administration of Traditional Chinese Medicine, School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong, China
| | - Lijun Xu
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.,Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Jing Tang
- Department of Anesthesia, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Liang Zhao
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.,Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| |
Collapse
|
34
|
Functional properties and mechanism of action of PPTQ, an allosteric agonist and low nanomolar positive allosteric modulator at GABAA receptors. Biochem Pharmacol 2018; 147:153-169. [DOI: 10.1016/j.bcp.2017.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 11/13/2017] [Indexed: 11/23/2022]
|
35
|
Feng HJ, Forman SA. Comparison of αβδ and αβγ GABA A receptors: Allosteric modulation and identification of subunit arrangement by site-selective general anesthetics. Pharmacol Res 2017; 133:289-300. [PMID: 29294355 DOI: 10.1016/j.phrs.2017.12.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 12/27/2022]
Abstract
GABAA receptors play a dominant role in mediating inhibition in the mature mammalian brain, and defects of GABAergic neurotransmission contribute to the pathogenesis of a variety of neurological and psychiatric disorders. Two types of GABAergic inhibition have been described: αβγ receptors mediate phasic inhibition in response to transient high-concentrations of synaptic GABA release, and αβδ receptors produce tonic inhibitory currents activated by low-concentration extrasynaptic GABA. Both αβδ and αβγ receptors are important targets for general anesthetics, which induce apparently different changes both in GABA-dependent receptor activation and in desensitization in currents mediated by αβγ vs. αβδ receptors. Many of these differences are explained by correcting for the high agonist efficacy of GABA at most αβγ receptors vs. much lower efficacy at αβδ receptors. The stoichiometry and subunit arrangement of recombinant αβγ receptors are well established as β-α-γ-β-α, while those of αβδ receptors remain controversial. Importantly, some potent general anesthetics selectively bind in transmembrane inter-subunit pockets of αβγ receptors: etomidate acts at β+/α- interfaces, and the barbiturate R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB) acts at α+/β- and γ+/β- interfaces. Thus, these drugs are useful as structural probes in αβδ receptors formed from free subunits or concatenated subunit assemblies designed to constrain subunit arrangement. Although a definite conclusion cannot be drawn, studies using etomidate and R-mTFD-MPAB support the idea that recombinant α1β3δ receptors may share stoichiometry and subunit arrangement with α1β3γ2 receptors.
Collapse
Affiliation(s)
- Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
| |
Collapse
|
36
|
Amin J, Subbarayan MS. Orthosteric- versus allosteric-dependent activation of the GABA A receptor requires numerically distinct subunit level rearrangements. Sci Rep 2017; 7:7770. [PMID: 28798394 PMCID: PMC5552871 DOI: 10.1038/s41598-017-08031-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 07/07/2017] [Indexed: 12/05/2022] Open
Abstract
Anaesthetic molecules act on synaptic transmission via the allosteric modulation of ligand-gated chloride channels, such as hetero-oligomeric α1β2γ2 GABAA receptors. To elucidate the overall activation paradigm via allosteric versus orthosteric sites, we used highly homologous, but homo-oligomeric, ρ1 receptors that are contrastingly insensitive to anaesthetics and respond partially to several full GABA α1β2γ2 receptor agonists. Here, we coexpressed varying ratios of RNAs encoding the wild-type and the mutated ρ1 subunits, which are anaesthetic-sensitive and respond with full efficacy to partial GABA agonists, to generate distinct ensembles of receptors containing five, four, three, two, one, or zero mutated subunits. Using these experiments, we then demonstrate that, in the pentamer, three anaesthetic-sensitive ρ1 subunits are needed to impart full efficacy to the partial GABA agonists. By contrast, five anaesthetic-sensitive subunits are required for direct activation by anaesthetics alone, and only one anaesthetic-sensitive subunit is sufficient to confer the anaesthetic-dependent potentiation to the GABA current. In conclusion, our data indicate that GABA and anaesthetics holistically activate the GABAA ρ1 receptor through distinct subunit level rearrangements and suggest that in contrast to the global impact of GABA via orthosteric sites, the force of anaesthetics through allosteric sites may not propagate to the neighbouring subunits and, thus, may have only a local and limited effect on the ρ1 GABAA receptor model system.
Collapse
Affiliation(s)
- Jahanshah Amin
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA.
| | - Meena S Subbarayan
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| |
Collapse
|
37
|
Shin DJ, Germann AL, Steinbach JH, Akk G. The Actions of Drug Combinations on the GABA A Receptor Manifest as Curvilinear Isoboles of Additivity. Mol Pharmacol 2017; 92:556-563. [PMID: 28790148 DOI: 10.1124/mol.117.109595] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/07/2017] [Indexed: 02/04/2023] Open
Abstract
Drug interactions are often analyzed in terms of isobolograms. In the isobologram, the line connecting the axial points corresponding to the concentrations of two different drugs that produce an effect of the same magnitude is termed an isobole of additivity. Although the isobole of additivity can be a straight line in some special cases, previous work has proposed that it is curvilinear when the two drugs differ in their maximal effects or Hill slopes. Modulators of transmitter-gated ion channels have a wide range of maximal effects as well as Hill slopes, suggesting that the isoboles for drug actions on ion channel function are not linear. In this study, we have conducted an analysis of direct activation and potentiation of the human α1β2γ2L GABAA receptor to demonstrate that: 1) curvilinear isoboles of additivity are predicted by a concerted transition model where the binding of each GABAergic drug additively and independently reduces the free energy of the open receptor compared with the closed receptor; and 2) experimental data for receptor activation using the agonist pair of GABA and propofol or potentiation of responses to a low concentration of GABA by the drug pair of alfaxalone and propofol agree very well with predictions. The approach assuming independent energetic contributions from GABAergic drugs enables, at least for the drug combinations tested, a straightforward method to accurately predict functional responses to any combination of concentrations.
Collapse
Affiliation(s)
- Daniel J Shin
- Department of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.), and the Taylor Family Institute for Innovative Psychiatric Research (J.H.S., G.A.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Allison L Germann
- Department of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.), and the Taylor Family Institute for Innovative Psychiatric Research (J.H.S., G.A.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Joe Henry Steinbach
- Department of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.), and the Taylor Family Institute for Innovative Psychiatric Research (J.H.S., G.A.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Gustav Akk
- Department of Anesthesiology (D.J.S., A.L.G., J.H.S., G.A.), and the Taylor Family Institute for Innovative Psychiatric Research (J.H.S., G.A.), Washington University School of Medicine in St. Louis, St. Louis, Missouri
| |
Collapse
|
38
|
Tryptophan and Cysteine Mutations in M1 Helices of α1β3γ2L γ-Aminobutyric Acid Type A Receptors Indicate Distinct Intersubunit Sites for Four Intravenous Anesthetics and One Orphan Site. Anesthesiology 2017; 125:1144-1158. [PMID: 27753644 DOI: 10.1097/aln.0000000000001390] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND γ-Aminobutyric acid type A (GABAA) receptors mediate important effects of intravenous general anesthetics. Photolabel derivatives of etomidate, propofol, barbiturates, and a neurosteroid get incorporated in GABAA receptor transmembrane helices M1 and M3 adjacent to intersubunit pockets. However, photolabels have not been consistently targeted at heteromeric αβγ receptors and do not form adducts with all contact residues. Complementary approaches may further define anesthetic sites in typical GABAA receptors. METHODS Two mutation-based strategies, substituted tryptophan sensitivity and substituted cysteine modification-protection, combined with voltage-clamp electrophysiology in Xenopus oocytes, were used to evaluate interactions between four intravenous anesthetics and six amino acids in M1 helices of α1, β3, and γ2L GABAA receptor subunits: two photolabeled residues, α1M236 and β3M227, and their homologs. RESULTS Tryptophan substitutions at α1M236 and positional homologs β3L231 and γ2L246 all caused spontaneous channel gating and reduced γ-aminobutyric acid EC50. Substituted cysteine modification experiments indicated etomidate protection at α1L232C and α1M236C, R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirinylphenyl) barbituric acid protection at β3M227C and β3L231C, and propofol protection at α1M236C and β3M227C. No alphaxalone protection was evident at the residues the authors explored, and none of the tested anesthetics protected γ2I242C or γ2L246C. CONCLUSIONS All five intersubunit transmembrane pockets of GABAA receptors display similar allosteric linkage to ion channel gating. Substituted cysteine modification and protection results were fully concordant with anesthetic photolabeling at α1M236 and β3M227 and revealed overlapping noncongruent sites for etomidate and propofol in β-α interfaces and R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirinylphenyl) barbituric acid and propofol in α-β and γ-β interfaces. The authors' results identify the α-γ transmembrane interface as a potentially unique orphan modulator site.
Collapse
|
39
|
Abstract
OBJECTIVE Myoclonus, a common complication during intravenous induction with etomidate, is bothersome to both anesthesiologists and patients. This study explored the preventive effect of pretreatment with propofol on etomidate-related myoclonus. METHODS This was a prospective, double-blind, clinical, randomized controlled study. Totally, 363 patients who were scheduled for a short-duration, painless gastrointestinal endoscopy were divided into 5 groups. Four groups received 0 mg/kg (E group), 0.25 mg/kg (LPE group), 0.50 mg/kg (MPE group), or 0.75 mg/kg (HPE group) propofol pretreatment before etomidate anesthesia. Another group only received 1 to 2 mg/kg of propofol (P group) as anesthesia. The incidence and severity of myoclonus, patient circulation and respiratory status, and intraoperative and postoperative complications were recorded. RESULTS The incidence of myoclonus in the LPE group (26.8%), MPE group (16.4%), HPE group (14.9%), and P group (0) was lower than the E group (48.6%, P < .05). The incidence of grade 1, 2, and 3 of myoclonus in the LPE group, MPE group, HPE group, and P group was significantly lower than the E group, and that in the P group was lower than the LPE group (P < .05). The incidence of hypoxemia in the P group was higher than the E group, and the incidence of adverse events in the HPE group and P group was lower than the E group (P < .05). DISCUSSION Pretreatment with propofol was feasible for preventing etomidate-related myoclonus. Furthermore, as propofol dosage increased, its effect on reducing the incidence and severity of myoclonic movements induced by etomidate increased.
Collapse
Affiliation(s)
- Jinfeng Liu
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Rongfang Liu
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
- Affiliate Hospital of HeBei University Department of Anesthesiology, Affiliate Hospital of HeBei University, No.212 of Yuhua East Road, Baoding
| | - Chao Meng
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Zhenhua Cai
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Xiaoqi Dai
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Chao Deng
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Jiahang Zhang
- Department of Anesthesiology, The Second Affiliated Hospital, Harbin Medical University, and the Hei Long Jiang Province Key Lab of Research on Anesthesiology and Critical Care Medicine, Harbin
| | - Huacheng Zhou
- Department of Anesthesiology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| |
Collapse
|
40
|
Curcumol allosterically modulates GABA(A) receptors in a manner distinct from benzodiazepines. Sci Rep 2017; 7:46654. [PMID: 28436443 PMCID: PMC5402396 DOI: 10.1038/srep46654] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/22/2017] [Indexed: 12/11/2022] Open
Abstract
Inhibitory A type γ-aminobutyric acid receptors (GABAARs) play a pivotal role in orchestrating various brain functions and represent an important molecular target in neurological and psychiatric diseases, necessitating the need for the discovery and development of novel modulators. Here, we show that a natural compound curcumol, acts as an allosteric enhancer of GABAARs in a manner distinct from benzodiazepines. Curcumol markedly facilitated GABA-activated currents and shifted the GABA concentration-response curve to the left in cultured hippocampal neurons. When co-applied with the classical benzodiazepine diazepam, curcumol further potentiated GABA-induced currents. In contrast, in the presence of a saturating concentration of menthol, a positive modulator for GABAAR, curcumol failed to further enhance GABA-induced currents, suggesting shared mechanisms underlying these two agents on GABAARs. Moreover, the benzodiazepine antagonist flumazenil did not alter the enhancement of GABA response by curcumol and menthol, but abolished that by DZP. Finally, mutations at the β2 or γ2 subunit predominantly eliminated modulation of recombinant GABAARs by curcumol and menthol, or diazepam, respectively. Curcumol may therefore exert its actions on GABAARs at sites distinct from benzodiazepine sites. These findings shed light on the future development of new therapeutics drugs targeting GABAARs.
Collapse
|
41
|
Maldifassi MC, Wongsamitkul N, Baur R, Sigel E. Xenopus Oocytes: Optimized Methods for Microinjection, Removal of Follicular Cell Layers, and Fast Solution Changes in Electrophysiological Experiments. J Vis Exp 2016. [PMID: 28117773 DOI: 10.3791/55034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The Xenopus oocyte as a heterologous expression system for proteins, was first described by Gurdon et al.1 and has been widely used since its discovery (References 2 - 3, and references therein). A characteristic that makes the oocyte attractive for foreign channel expression is the poor abundance of endogenous ion channels4. This expression system has proven useful for the characterization of many proteins, among them ligand-gated ion channels. The expression of GABAA receptors in Xenopus oocytes and their functional characterization is described here, including the isolation of oocytes, microinjections with cRNA, the removal of follicular cell layers, and fast solution changes in electrophysiological experiments. The procedures were optimized in this laboratory5,6 and deviate from the ones routinely used7-9. Traditionally, denuded oocytes are prepared with a prolonged collagenase treatment of ovary lobes at RT, and these denuded oocytes are microinjected with mRNA. Using the optimized methods, diverse membrane proteins have been expressed and studied with this system, such as recombinant GABAA receptors10-12, human recombinant chloride channels13, Trypanosome potassium channels14, and a myo-inositol transporter15, 16. The methods detailed here may be applied to the expression of any protein of choice in Xenopus oocytes, and the rapid solution change can be used to study other ligand-gated ion channels.
Collapse
Affiliation(s)
| | - Nisa Wongsamitkul
- Institute of Biochemistry and Molecular Medicine, University of Bern
| | - Roland Baur
- Institute of Biochemistry and Molecular Medicine, University of Bern
| | - Erwin Sigel
- Institute of Biochemistry and Molecular Medicine, University of Bern;
| |
Collapse
|
42
|
Chiara DC, Jounaidi Y, Zhou X, Savechenkov PY, Bruzik KS, Miller KW, Cohen JB. General Anesthetic Binding Sites in Human α4β3δ γ-Aminobutyric Acid Type A Receptors (GABAARs). J Biol Chem 2016; 291:26529-26539. [PMID: 27821594 PMCID: PMC5159512 DOI: 10.1074/jbc.m116.753335] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/14/2016] [Indexed: 01/08/2023] Open
Abstract
Extrasynaptic γ-aminobutyric acid type A receptors (GABAARs),which contribute generalized inhibitory tone to the mammalian brain, are major targets for general anesthetics. To identify anesthetic binding sites in an extrasynaptic GABAAR, we photolabeled human α4β3δ GABAARs purified in detergent with [3H]azietomidate and a barbiturate, [3H]R-mTFD-MPAB, photoreactive anesthetics that bind with high selectivity to distinct but homologous intersubunit binding sites in the transmembrane domain of synaptic α1β3γ2 GABAARs. Based upon 3H incorporation into receptor subunits resolved by SDS-PAGE, there was etomidate-inhibitable labeling by [3H]azietomidate in the α4 and β3 subunits and barbiturate-inhibitable labeling by [3H]R-mTFD-MPAB in the β3 subunit. These sites did not bind the anesthetic steroid alphaxalone, which enhanced photolabeling, or DS-2, a δ subunit-selective positive allosteric modulator, which neither enhanced nor inhibited photolabeling. The amino acids labeled by [3H]azietomidate or [3H]R-mTFD-MPAB were identified by N-terminal sequencing of fragments isolated by HPLC fractionation of enzymatically digested subunits. No evidence was found for a δ subunit contribution to an anesthetic binding site. [3H]azietomidate photolabeling of β3Met-286 in βM3 and α4Met-269 in αM1 that was inhibited by etomidate but not by R-mTFD-MPAB established that etomidate binds to a site at the β3+-α4- interface equivalent to its site in α1β3γ2 GABAARs. [3H]Azietomidate and [3H]R-mTFD-MPAB photolabeling of β3Met-227 in βM1 established that these anesthetics also bind to a homologous site, most likely at the β3+-β3- interface, which suggests a subunit arrangement of β3α4β3δβ3.
Collapse
Affiliation(s)
| | - Youssef Jounaidi
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Xiaojuan Zhou
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Pavel Y Savechenkov
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60612
| | - Karol S Bruzik
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60612
| | - Keith W Miller
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | | |
Collapse
|
43
|
Woll KA, Murlidaran S, Pinch BJ, Hénin J, Wang X, Salari R, Covarrubias M, Dailey WP, Brannigan G, Garcia BA, Eckenhoff RG. A Novel Bifunctional Alkylphenol Anesthetic Allows Characterization of γ-Aminobutyric Acid, Type A (GABAA), Receptor Subunit Binding Selectivity in Synaptosomes. J Biol Chem 2016; 291:20473-86. [PMID: 27462076 PMCID: PMC5034043 DOI: 10.1074/jbc.m116.736975] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/25/2016] [Indexed: 12/19/2022] Open
Abstract
Propofol, an intravenous anesthetic, is a positive modulator of the GABAA receptor, but the mechanistic details, including the relevant binding sites and alternative targets, remain disputed. Here we undertook an in-depth study of alkylphenol-based anesthetic binding to synaptic membranes. We designed, synthesized, and characterized a chemically active alkylphenol anesthetic (2-((prop-2-yn-1-yloxy)methyl)-5-(3-(trifluoromethyl)-3H-diazirin-3-yl)phenol, AziPm-click (1)), for affinity-based protein profiling (ABPP) of propofol-binding proteins in their native state within mouse synaptosomes. The ABPP strategy captured ∼4% of the synaptosomal proteome, including the unbiased capture of five α or β GABAA receptor subunits. Lack of γ2 subunit capture was not due to low abundance. Consistent with this, independent molecular dynamics simulations with alchemical free energy perturbation calculations predicted selective propofol binding to interfacial sites, with higher affinities for α/β than γ-containing interfaces. The simulations indicated hydrogen bonding is a key component leading to propofol-selective binding within GABAA receptor subunit interfaces, with stable hydrogen bonds observed between propofol and α/β cavity residues but not γ cavity residues. We confirmed this by introducing a hydrogen bond-null propofol analogue as a protecting ligand for targeted-ABPP and observed a lack of GABAA receptor subunit protection. This investigation demonstrates striking interfacial GABAA receptor subunit selectivity in the native milieu, suggesting that asymmetric occupancy of heteropentameric ion channels by alkylphenol-based anesthetics is sufficient to induce modulation of activity.
Collapse
Affiliation(s)
- Kellie A Woll
- From the Departments of Anesthesiology and Critical Care and Pharmacology and
| | | | - Benika J Pinch
- the Department of Chemistry, University of Pennsylvania School of Arts and Sciences, Philadelphia, Pennsylvania 19104
| | - Jérôme Hénin
- the Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS UMR 8251 and Université Paris Diderot, 5013 Paris, France, and
| | - Xiaoshi Wang
- the Epigenetics Program, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Reza Salari
- the Center for Computational and Integrative Biology and Department of Physics, Rutgers University, Camden, New Jersey 08102
| | - Manuel Covarrubias
- the Department of Neuroscience and Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - William P Dailey
- the Department of Chemistry, University of Pennsylvania School of Arts and Sciences, Philadelphia, Pennsylvania 19104
| | - Grace Brannigan
- the Center for Computational and Integrative Biology and Department of Physics, Rutgers University, Camden, New Jersey 08102
| | - Benjamin A Garcia
- the Epigenetics Program, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | | |
Collapse
|
44
|
Mutagenesis and computational docking studies support the existence of a histamine binding site at the extracellular β3+β3− interface of homooligomeric β3 GABA A receptors. Neuropharmacology 2016; 108:252-63. [DOI: 10.1016/j.neuropharm.2016.04.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 04/06/2016] [Accepted: 04/28/2016] [Indexed: 12/31/2022]
|
45
|
Fu B, Wang Y, Yang H, Yu T. Effects of Etomidate on GABAergic and Glutamatergic Transmission in Rat Thalamocortical Slices. Neurochem Res 2016; 41:3181-3191. [PMID: 27561291 DOI: 10.1007/s11064-016-2042-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 08/10/2016] [Accepted: 08/22/2016] [Indexed: 12/14/2022]
Abstract
Although accumulative evidence indicates that the thalamocortical system is an important target for general anesthetics, the underlying mechanisms of anesthetic action on thalamocortical neurotransmission are not fully understood. The aim of the study is to explore the action of etomidate on glutamatergic and GABAergic transmission in rat thalamocortical slices by using whole cell patch-clamp recording. We found that etomidate mainly prolonged the decay time of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs), without changing the frequency. Furthermore, etomidate not only prolonged the decay time of miniature inhibitory postsynaptic currents (mIPSCs) but also increased the amplitude. On the other hand, etomidate significantly decreased the frequency of spontaneous glutamatergic excitatory postsynaptic currents (sEPSCs), without altering the amplitude or decay time in the absence of bicuculline. When GABAA receptors were blocked using bicuculline, the effects of etomidate on sEPSCs were mostly eliminated. These results suggest that etomidate enhances GABAergic transmission mainly through postsynaptic mechanism in thalamocortical neuronal network. Etomidate attenuates glutamatergic transmission predominantly through presynaptic action and requires presynaptic GABAA receptors involvement.
Collapse
Affiliation(s)
- Bao Fu
- Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Yuan Wang
- Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Hao Yang
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian road 149, Zunyi, 563000, Guizhou, China
| | - Tian Yu
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian road 149, Zunyi, 563000, Guizhou, China.
| |
Collapse
|
46
|
Maldifassi MC, Baur R, Sigel E. Molecular mode of action of CGS 9895 at α1β2γ2GABAAreceptors. J Neurochem 2016; 138:722-30. [DOI: 10.1111/jnc.13711] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/01/2016] [Accepted: 06/04/2016] [Indexed: 01/09/2023]
Affiliation(s)
- Maria C. Maldifassi
- Institute of Biochemistry and Molecular Medicine; University of Bern; Bern Switzerland
| | - Roland Baur
- Institute of Biochemistry and Molecular Medicine; University of Bern; Bern Switzerland
| | - Erwin Sigel
- Institute of Biochemistry and Molecular Medicine; University of Bern; Bern Switzerland
| |
Collapse
|
47
|
Puthenkalam R, Hieckel M, Simeone X, Suwattanasophon C, Feldbauer RV, Ecker GF, Ernst M. Structural Studies of GABAA Receptor Binding Sites: Which Experimental Structure Tells us What? Front Mol Neurosci 2016; 9:44. [PMID: 27378845 PMCID: PMC4910578 DOI: 10.3389/fnmol.2016.00044] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 05/25/2016] [Indexed: 01/23/2023] Open
Abstract
Atomic resolution structures of cys-loop receptors, including one of a γ-aminobutyric acid type A receptor (GABAA receptor) subtype, allow amazing insights into the structural features and conformational changes that these pentameric ligand-gated ion channels (pLGICs) display. Here we present a comprehensive analysis of more than 30 cys-loop receptor structures of homologous proteins that revealed several allosteric binding sites not previously described in GABAA receptors. These novel binding sites were examined in GABAA receptor homology models and assessed as putative candidate sites for allosteric ligands. Four so far undescribed putative ligand binding sites were proposed for follow up studies based on their presence in the GABAA receptor homology models. A comprehensive analysis of conserved structural features in GABAA and glycine receptors (GlyRs), the glutamate gated ion channel, the bacterial homologs Erwinia chrysanthemi (ELIC) and Gloeobacter violaceus GLIC, and the serotonin type 3 (5-HT3) receptor was performed. The conserved features were integrated into a master alignment that led to improved homology models. The large fragment of the intracellular domain that is present in the structure of the 5-HT3 receptor was utilized to generate GABAA receptor models with a corresponding intracellular domain fragment. Results of mutational and photoaffinity ligand studies in GABAA receptors were analyzed in the light of the model structures. This led to an assignment of candidate ligands to two proposed novel pockets, candidate binding sites for furosemide and neurosteroids in the trans-membrane domain were identified. The homology models can serve as hypotheses generators, and some previously controversial structural interpretations of biochemical data can be resolved in the light of the presented multi-template approach to comparative modeling. Crystal and cryo-EM microscopic structures of the closest homologs that were solved in different conformational states provided important insights into structural rearrangements of binding sites during conformational transitions. The impact of structural variation and conformational motion on the shape of the investigated binding sites was analyzed. Rules for best template and alignment choice were obtained and can generally be applied to modeling of cys-loop receptors. Overall, we provide an updated structure based view of ligand binding sites present in GABAA receptors.
Collapse
Affiliation(s)
- Roshan Puthenkalam
- Department of Molecular Neurosciences, Medical University of ViennaVienna, Austria
| | - Marcel Hieckel
- Department of Molecular Neurosciences, Medical University of ViennaVienna, Austria
| | - Xenia Simeone
- Department of Molecular Neurosciences, Medical University of ViennaVienna, Austria
| | | | - Roman V. Feldbauer
- Austrian Research Institute for Artificial Intelligence (OFAI)Vienna, Austria
| | - Gerhard F. Ecker
- Department of Pharmaceutical Chemistry, University of ViennaVienna, Austria
| | - Margot Ernst
- Department of Molecular Neurosciences, Medical University of ViennaVienna, Austria
| |
Collapse
|
48
|
Maldifassi MC, Baur R, Pierce D, Nourmahnad A, Forman SA, Sigel E. Novel positive allosteric modulators of GABAA receptors with anesthetic activity. Sci Rep 2016; 6:25943. [PMID: 27198062 PMCID: PMC4873749 DOI: 10.1038/srep25943] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 04/25/2016] [Indexed: 01/08/2023] Open
Abstract
GABAA receptors are the main inhibitory neurotransmitter receptors in the brain and are targets for numerous clinically important drugs such as benzodiazepines, anxiolytics and anesthetics. We previously identified novel ligands of the classical benzodiazepine binding pocket in α1β2γ2 GABAA receptors using an experiment-guided virtual screening (EGVS) method. This screen also identified novel ligands for intramembrane low affinity diazepam site(s). In the current study we have further characterized compounds 31 and 132 identified with EGVS as well as 4-O-methylhonokiol. We investigated the site of action of these compounds in α1β2γ2 GABAA receptors expressed in Xenopus laevis oocytes using voltage-clamp electrophysiology combined with a benzodiazepine site antagonist and transmembrane domain mutations. All three compounds act mainly through the two β+/α− subunit transmembrane interfaces of the GABAA receptors. We then used concatenated receptors to dissect the involvement of individual β+/α− interfaces. We further demonstrated that these compounds have anesthetic activity in a small aquatic animal model, Xenopus laevis tadpoles. The newly identified compounds may serve as scaffolds for the development of novel anesthetics.
Collapse
Affiliation(s)
- Maria C Maldifassi
- Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland
| | - Roland Baur
- Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland
| | - David Pierce
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts
| | - Anahita Nourmahnad
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, 02114 Massachusetts
| | - Erwin Sigel
- Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland
| |
Collapse
|
49
|
Ziemba AM, Forman SA. Correction for Inhibition Leads to an Allosteric Co-Agonist Model for Pentobarbital Modulation and Activation of α1β3γ2L GABAA Receptors. PLoS One 2016; 11:e0154031. [PMID: 27110714 PMCID: PMC4844112 DOI: 10.1371/journal.pone.0154031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/07/2016] [Indexed: 11/19/2022] Open
Abstract
Background Pentobarbital, like propofol and etomidate, produces important general anesthetic effects through GABAA receptors. Photolabeling also indicates that pentobarbital binds to some of the same sites where propofol and etomidate act. Quantitative allosteric co-agonist models for propofol and etomidate account for modulatory and agonist effects in GABAA receptors and have proven valuable in establishing drug site characteristics and for functional analysis of mutants. We therefore sought to establish an allosteric co-agonist model for pentobarbital activation and modulation of α1β3γ2L receptors, using a novel approach to first correct pentobarbital activation data for inhibitory effects in the same concentration range. Methods Using oocyte-expressed α1β3γ2L GABAA receptors and two-microelectrode voltage-clamp, we quantified modulation of GABA responses by a low pentobarbital concentration and direct effects of high pentobarbital concentrations, the latter displaying mixed agonist and inhibitory effects. We then isolated and quantified pentobarbital inhibition in activated receptors using a novel single-sweep “notch” approach, and used these results to correct steady-state direct activation for inhibition. Results Combining results for GABA modulation and corrected direct activation, we estimated receptor open probability and optimized parameters for a Monod-Wyman-Changeux allosteric co-agonist model. Inhibition by pentobarbital was consistent with two sites with IC50s near 1 mM, while co-agonist model parameters suggest two allosteric pentobarbital agonist sites characterized by KPB ≈ 5 mM and high efficacy. The results also indicate that pentobarbital may be a more efficacious agonist than GABA. Conclusions Our novel approach to quantifying both inhibitory and co-agonist effects of pentobarbital provides a basis for future structure-function analyses of GABAA receptor mutations in putative pentobarbital binding sites.
Collapse
Affiliation(s)
- Alexis M. Ziemba
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, United States of America
| | - Stuart A. Forman
- Department of Anesthesia Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, United States of America
- * E-mail:
| |
Collapse
|