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Liu LL, He JL, Yuen VMY, Xu X, Guan X, Qiu Y, Wang Y, Jian CJ, Wen Z, Liu KX. Alterations in whole-brain dynamic functional stability during memory tasks under dexmedetomidine sedation. Front Neurol 2022; 13:928389. [PMID: 36388179 PMCID: PMC9650205 DOI: 10.3389/fneur.2022.928389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 10/11/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose This study aimed to explore the neurological effects of dexmedetomidine-induced sedation on memory using functional stability, a whole-brain voxel-wise dynamic functional connectivity approach. Methods A total of 16 participants (10 men) underwent auditory memory task-related fMRI in the awake state and under dexmedetomidine sedation. Explicit and implicit memory tests were conducted 4 h after ceasing dexmedetomidine administration. One-sample Wilcoxon signed rank test was applied to determine the formation of explicit and implicit memory in the two states. Functional stability was calculated and compared voxel-wise between the awake and sedated states. The association between functional stability and memory performance was also assessed. Results In the awake baseline tests, explicit and implicit memory scores were significantly different from zero (p < 0.05). In the tests under sedation, explicit and implicit memory scores were not significantly different from zero. Compared to that at wakeful baseline, functional stability during light sedation was reduced in the medial prefrontal cortex, left angular gyrus, and right hippocampus (all clusters, p < 0.05, GRF-corrected), whereas the left superior temporal gyrus exhibited higher functional stability (cluster p < 0.05, GRF-corrected). No significant associations were observed between functional stability and memory test scores. Conclusions The distribution and patterns of alterations in functional stability during sedation illustrate the modulation of functional architecture by dexmedetomidine from a dynamic perspective. Our findings provide novel insight into the dynamic brain functional networks underlying consciousness and memory in humans.
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Affiliation(s)
- Lin-Lin Liu
- Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Jian-Long He
- Department of Radiology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- Radiology Center, Department of Medical Imaging, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Vivian Man-Ying Yuen
- Department of Anesthesiology and Perioperative Medicine, Hong Kong Children's Hospital, Hong Kong, Hong Kong SAR, China
| | - Xuebing Xu
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Xuan Guan
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Yan Qiu
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Yingzi Wang
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Chao-Jun Jian
- Department of Anesthesiology, The University of Hong Kong–Shenzhen Hospital, Shenzhen, China
| | - Zhibo Wen
- Department of Radiology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- Zhibo Wen
| | - Ke-Xuan Liu
- Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Ke-Xuan Liu
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Vogt KM, Pryor KO. Anesthesia and the neurobiology of fear and posttraumatic stress disorder. Curr Opin Anaesthesiol 2022; 35:593-599. [PMID: 35993581 PMCID: PMC9469898 DOI: 10.1097/aco.0000000000001176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE OF REVIEW Dysfunction of fear memory systems underlie a cluster of clinically important and highly prevalent psychological morbidities seen in perioperative and critical care patients, most archetypally posttraumatic stress disorder (PTSD). Several sedative-hypnotics and analgesics are known to modulate fear systems, and it is theoretically plausible that clinical decisions of the anesthesiologist could impact psychological outcomes. This review aims to provide a focused synthesis of relevant literature from multiple fields of research. RECENT FINDINGS There is evidence in some contexts that unconscious fear memory systems are less sensitive to anesthetics than are conscious memory systems. Opiates may suppress the activation of fear systems and have benefit in the prevention of PTSD following trauma. There is inconsistent evidence that the use of propofol and benzodiazepines for sedation following trauma may potentiate the development of PTSD relative to other drugs. The benefits of ketamine seen in the treatment of major depression are not clearly replicated in PTSD-cluster psychopathologies, and its effects on fear processes are complex. SUMMARY There are multiple theoretical mechanisms by which anesthetic drugs can modulate fear systems and clinically important fear-based psychopathologies. The current state of research provides some evidence to support further hypothesis investigation. However, the absence of effectiveness studies and the inconsistent signals from smaller studies provide insufficient evidence to currently offer firm clinical guidance.
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Affiliation(s)
- Keith M. Vogt
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, School of Medicine
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh
- Center for the Neural Basis of Cognition
- Clinical and Translational Science Institute, University of Pittsburgh
| | - Kane O. Pryor
- Department of Anesthesiology, Weill Cornell Medicine
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Stafford P, Puglia M, Haydar B. Dexmedetomidine and remifentanil as sole anesthetics in infants: Questionable hypnosis. Paediatr Anaesth 2021; 31:250-251. [PMID: 33539674 DOI: 10.1111/pan.14073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 10/28/2020] [Accepted: 11/08/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Patrick Stafford
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Michael Puglia
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Bishr Haydar
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
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Radek L, Kallionpää R, Karvonen M, Scheinin A, Maksimow A, Långsjö J, Kaisti K, Vahlberg T, Revonsuo A, Scheinin H, Valli K. Dreaming and awareness during dexmedetomidine- and propofol-induced unresponsiveness. Br J Anaesth 2018; 121:260-269. [DOI: 10.1016/j.bja.2018.03.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/01/2018] [Accepted: 03/27/2018] [Indexed: 11/26/2022] Open
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Spoken words are processed during dexmedetomidine-induced unresponsiveness. Br J Anaesth 2018; 121:270-280. [PMID: 29935582 DOI: 10.1016/j.bja.2018.04.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/13/2018] [Accepted: 04/30/2018] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Studying the effects of anaesthetic drugs on the processing of semantic stimuli could yield insights into how brain functions change in the transition from wakefulness to unresponsiveness. Here, we explored the N400 event-related potential during dexmedetomidine- and propofol-induced unresponsiveness. METHODS Forty-seven healthy subjects were randomised to receive either dexmedetomidine (n=23) or propofol (n=24) in this open-label parallel-group study. Loss of responsiveness was achieved by stepwise increments of pseudo-steady-state plasma concentrations, and presumed loss of consciousness was induced using 1.5 times the concentration required for loss of responsiveness. Pre-recorded spoken sentences ending either with an expected (congruous) or an unexpected (incongruous) word were presented during unresponsiveness. The resulting electroencephalogram data were analysed for the presence of the N400 component, and for the N400 effect defined as the difference between the N400 components elicited by congruous and incongruous stimuli, in the time window 300-600 ms post-stimulus. Recognition of the presented stimuli was tested after recovery of responsiveness. RESULTS The N400 effect was not observed during dexmedetomidine- or propofol-induced unresponsiveness. The N400 component, however, persisted during dexmedetomidine administration. The N400 component elicited by congruous stimuli during unresponsiveness in the dexmedetomidine group resembled the large component evoked by incongruous stimuli at the awake baseline. After recovery, no recognition of the stimuli heard during unresponsiveness occurred. CONCLUSIONS Dexmedetomidine and propofol disrupt the discrimination of congruous and incongruous spoken sentences, and recognition memory at loss of responsiveness. However, the processing of words is partially preserved during dexmedetomidine-induced unresponsiveness. CLINICAL TRIAL REGISTRATION NCT01889004.
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Bègue I, Blakemore R, Klug J, Cojan Y, Galli S, Berney A, Aybek S, Vuilleumier P. Metacognition of visuomotor decisions in conversion disorder. Neuropsychologia 2018; 114:251-265. [PMID: 29698734 DOI: 10.1016/j.neuropsychologia.2018.04.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 12/21/2022]
Abstract
Motor conversion disorder (CD) entails genuine disturbances in the subjective experience of patients who maintain they are unable to perform a motor function, despite lack of apparent neurological damage. Abilities by which individuals assess their own capacities during performance in a task are called metacognitive, and distinctive impairment of such abilities is observed in several disorders of self-awareness such as blindsight and anosognosia. In CD, previous research has focused on the recruitment of motor and emotional brain systems, generally linking symptoms to altered limbic-motor interactions; however, metacognitive function has not been studied to our knowledge. Here we tested ten CD patients and ten age-gender matched controls during a visually-guided motor paradigm, previously employed in healthy controls (HC), allowing us to probe for motor awareness and metacognition. Participants had to draw straight trajectories towards a visual target while, unbeknownst to them, deviations were occasionally introduced in the reaching trajectory seen on the screen. Participants then reported both awareness of deviations and confidence in their response. Activity in premotor and cingulate cortex distinguished between conscious and unconscious movement corrections in controls better than patients. Critically, whereas controls engaged the left superior precuneus and middle temporal region during confidence judgments, CD patients recruited bilateral parahippocampal and amygdalo-hippocampal regions instead. These results reveal that distinct brain regions subserve metacognitive monitoring for HC and CD, pointing to different mechanisms and sources of information used to monitor and form confidence judgments of motor performance. While brain systems involved in sensory-motor integration and vision are more engaged in controls, CD patients may preferentially rely on memory and contextual associative processing, possibly accounting for how affect and memories can imbue current motor experience in these patients.
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Affiliation(s)
- Indrit Bègue
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland; Swiss Center for Affective Studies, University of Geneva, Switzerland; Department of Mental Health and Psychiatry, University Hospitals of Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, Switzerland.
| | - Rebekah Blakemore
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - Julian Klug
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - Yann Cojan
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - Silvio Galli
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - Alexandre Berney
- Service of Consultation-Liaison Psychiatry, Lausanne University Hospital, Lausanne, Switzerland
| | - Selma Aybek
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, Switzerland; Neurology Department, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Patrik Vuilleumier
- Laboratory of Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland; Swiss Center for Affective Studies, University of Geneva, Switzerland; Department of Mental Health and Psychiatry, University Hospitals of Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, Switzerland
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Scheinin H, Alkire EC, Scheinin A, Alkire MT, Kantonen O, Långsjö J. Using Positron Emission Tomography in Revealing the Mystery of General Anesthesia: Study Design Challenges and Opportunities. Methods Enzymol 2018; 603:279-303. [PMID: 29673531 DOI: 10.1016/bs.mie.2018.01.025] [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: 01/12/2023]
Abstract
Functional neuroimaging with positron emission tomography (PET) is one of the cornerstones for studying the central nervous system effects of general anesthetics and anesthesia mechanisms. General anesthesia offers a unique and safe way to directly manipulate consciousness, and can thus be used as a powerful research tool to study the neurobiology of human consciousness. In this chapter, we will address the possibilities of PET imaging in revealing the mysteries of general anesthesia and anesthetic induced unconsciousness and summarize some of the recent advancements in the field. Importantly, we will discuss possible ways to separate brain activity changes associated with the changing level of consciousness from the concentration or dose-dependent direct or indirect drug effects on the brain. We will try to demonstrate how state-of-the-art clinical pharmacology, use of specific anesthetic drugs, and innovative study design solutions could be utilized.
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Affiliation(s)
- Harry Scheinin
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Turku University Hospital, Turku, Finland; Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland.
| | - Emilee C Alkire
- The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
| | - Annalotta Scheinin
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Turku University Hospital, Turku, Finland
| | - Michael T Alkire
- The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States; VA Long Beach Healthcare System, Long Beach, CA, United States
| | - Oskari Kantonen
- Turku University Hospital, Turku, Finland; The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
| | - Jaakko Långsjö
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Tampere University Hospital, Tampere, Finland
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Hara M, Zhou ZY, Hemmings HC. α2-Adrenergic Receptor and Isoflurane Modulation of Presynaptic Ca2+ Influx and Exocytosis in Hippocampal Neurons. Anesthesiology 2016; 125:535-46. [PMID: 27337223 PMCID: PMC4988866 DOI: 10.1097/aln.0000000000001213] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Evidence indicates that the anesthetic-sparing effects of α2-adrenergic receptor (AR) agonists involve α2A-AR heteroreceptors on nonadrenergic neurons. Since volatile anesthetics inhibit neurotransmitter release by reducing synaptic vesicle (SV) exocytosis, the authors hypothesized that α2-AR agonists inhibit nonadrenergic SV exocytosis and thereby potentiate presynaptic inhibition of exocytosis by isoflurane. METHODS Quantitative imaging of fluorescent biosensors of action potential-evoked SV exocytosis (synaptophysin-pHluorin) and Ca influx (GCaMP6) were used to characterize presynaptic actions of the clinically used α2-AR agonists dexmedetomidine and clonidine, and their interaction with isoflurane, in cultured rat hippocampal neurons. RESULTS Dexmedetomidine (0.1 μM, n = 10) or clonidine (0.5 μM, n = 8) inhibited action potential-evoked exocytosis (54 ± 5% and 59 ± 8% of control, respectively; P < 0.001). Effects on exocytosis were blocked by the subtype-nonselective α2-AR antagonist atipamezole or the α2A-AR-selective antagonist BRL 44408 but not by the α2C-AR-selective antagonist JP 1302. Dexmedetomidine inhibited exocytosis and presynaptic Ca influx without affecting Ca coupling to exocytosis, consistent with an effect upstream of Ca-exocytosis coupling. Exocytosis coupled to both N-type and P/Q-type Ca channels was inhibited by dexmedetomidine or clonidine. Dexmedetomidine potentiated inhibition of exocytosis by 0.7 mM isoflurane (to 42 ± 5%, compared to 63 ± 8% for isoflurane alone; P < 0.05). CONCLUSIONS Hippocampal SV exocytosis is inhibited by α2A-AR activation in proportion to reduced Ca entry. These effects are additive with those of isoflurane, consistent with a role for α2A-AR presynaptic heteroreceptor inhibition of nonadrenergic synaptic transmission in the anesthetic-sparing effects of α2A-AR agonists.
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Affiliation(s)
- Masato Hara
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
- Department of Anesthesiology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Zhen-Yu Zhou
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Hugh C. Hemmings
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
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Kim SE, Ko IG, Kim CJ, Chung JY, Yi JW, Choi JH, Jang MS, Han JH. Dexmedetomidine promotes the recovery of the field excitatory postsynaptic potentials (fEPSPs) in rat hippocampal slices exposed to oxygen-glucose deprivation. Neurosci Lett 2016; 631:91-96. [PMID: 27546825 DOI: 10.1016/j.neulet.2016.08.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 08/14/2016] [Accepted: 08/18/2016] [Indexed: 11/20/2022]
Abstract
Dexmedetomidine (DEX), a selective α2 adrenergic agonist, is an anesthetic and sedative agent, and is reported to exert neuroprotective effects after hypoxic ischemia. However, there are few studies on the electrophysiological effect of DEX in hippocampal slices under ischemic conditions. The effects of DEX on field potential in hippocampal slices exposed to oxygen-glucose deprivation (OGD) were evaluated. Hippocampal slices were prepared from rats, and the evoked field excitatory postsynaptic potentials (fEPSPs) were recorded using the MED 64 system. Hypoxic-ischemia was induced by perfusion with glucose-free artificial cerebrospinal fluid (aCSF) bubbled with 95% N2 and 5% CO2, and hippocampal slices were perfused with DEX-added aCSF before, during, and after OGD induction. In the normal hippocampal slices, perfusion with 1 and 10μM DEX did not significantly decrease the normalized fEPSP amplitude, but 100μM DEX significantly reduced the fEPSP amplitude compared with its baseline control. The induction of OGD remarkably decreased the fEPSP amplitude, whereas the pre-, co-, and post-treatment of 10μM DEX gradually promoted recovery after washing out, and consequently the amplitude of fEPSP in DEX pre-, co-, and post-treated OGD slices were significantly higher than that in the untreated OGD slices at 10min and 60min after washing out. In particular, co-treatment with DEX conspicuously promoted the recovery of the fEPSP amplitude at the beginning of washing out. These results suggest the possibility of DEX as a therapeutic agent to prevent hypoxic-ischemic brain damage and promote functional recovery after ischemia.
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Affiliation(s)
- Sung-Eun Kim
- Department of Physiology, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Il-Gyu Ko
- Department of Physiology, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Chang-Ju Kim
- Department of Physiology, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Jun-Young Chung
- Department of Anesthesiology and Pain Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Jae-Woo Yi
- Department of Anesthesiology and Pain Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Jeong-Hyun Choi
- Department of Anesthesiology and Pain Medicine, Kyung Hee Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Myung-Soo Jang
- Department of Anesthesiology and Pain Medicine, Kyung Hee Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea
| | - Jin-Hee Han
- Department of Anesthesiology and Pain Medicine, Kyung Hee Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea.
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Ribeiro PO, Antunes LM, Nunes CS, Silva HB, Cunha RA, Tomé ÂR. The Effects of Different Concentrations of the α2-Adrenoceptor Agonist Medetomidine on Basal Excitatory Synaptic Transmission and Synaptic Plasticity in Hippocampal Slices of Adult Mice. Anesth Analg 2016; 120:1130-1137. [PMID: 25658314 DOI: 10.1213/ane.0000000000000636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND α2-Adrenoceptor agonists are used frequently in human and veterinary anesthesia as sedative/analgesic drugs. However, they can impair cognition. Little is known about the concentration-dependent effects of α2-adrenoceptor agonists on synaptic plasticity, the neurophysiological basis of learning and memory. Therefore, we investigated the effects of different concentrations of medetomidine, an α2-adrenoceptor agonist, on basal excitatory synaptic transmission and on 2 forms of synaptic plasticity: paired-pulse facilitation (PPF) and long-term potentiation (LTP). METHODS Evoked field excitatory postsynaptic potentials were recorded in Schaffer fibers-CA1 pyramidal cell synapses of mouse hippocampal slices, and the initial field excitatory postsynaptic potentials slope was measured. For basal synaptic transmission and PPF, increasing concentrations of medetomidine (1-200 μM) were applied to each slice. For LTP experiments, individual slices were used for each tested concentration of medetomidine (0.1-0.4 μM), where LTP induction and LTP maintenance were measured. RESULTS The lower tested concentrations of medetomidine decreased LTP in a concentration-dependent manner, whereas greater concentrations were required to decrease fiber volley amplitude and basal excitatory synaptic transmission. PPF was only affected by the greatest concentration (200 μM). CONCLUSIONS Medetomidine decreased LTP in the mouse hippocampus, in accordance with the ability of medetomidine to induce memory deficits.
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Affiliation(s)
- Patrícia O Ribeiro
- From the Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Department of Veterinary Sciences, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAD), University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, Vila Real, Portugal; Institute of Molecular and Cell Biology (IBMC), Porto, Portugal; Department of Sciences and Technology, Portuguese Open University, Delegação do Porto, Porto, Portugal; Anaesthesiology Service, Clinical Anaesthesiology Research Centre, Centro Hospitalar do Porto, Porto, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal; and Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
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Pryor KO, Root JC, Mehta M, Stern E, Pan H, Veselis RA, Silbersweig DA. Effect of propofol on the medial temporal lobe emotional memory system: a functional magnetic resonance imaging study in human subjects. Br J Anaesth 2015; 115 Suppl 1:i104-i113. [PMID: 26174294 DOI: 10.1093/bja/aev038] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Subclinical doses of propofol produce anterograde amnesia, characterized by an early failure of memory consolidation. It is unknown how propofol affects the amygdala-dependent emotional memory system, which modulates consolidation in the hippocampus in response to emotional arousal and neurohumoral stress. We present an event-related functional magnetic resonance imaging study of the effects of propofol on the emotional memory system in human subjects. METHODS Thirty-five healthy subjects were randomized to receive propofol, at an estimated brain concentration of 0.90 μg ml(-1), or placebo. During drug infusion, emotionally arousing and neutral images were presented in a continuous recognition task, while blood-oxygen-level-dependent activation responses were acquired. After a drug-free interval of 2 h, subsequent memory for successfully encoded items was assessed. Imaging analysis was performed using statistical parametric mapping and behavioural analysis using signal detection models. RESULTS Propofol had no effect on the stereotypical amygdalar response to emotional arousal, but caused marked suppression of the hippocampal response. Propofol caused memory performance to become uncoupled from amygdalar activation, but it remained correlated with activation in the posterior hippocampus, which decreased in proportion to amnesia. CONCLUSIONS Propofol is relatively ineffective at suppressing amygdalar activation at sedative doses, but abolishes emotional modulation and causes amnesia via mechanisms that commonly involve hyporesponsiveness of the hippocampus. These findings raise the possibility that amygdala-dependent fear systems may remain intact even when a patient has diminished memory of events. This may be of clinical importance in the perioperative development of fear-based psychopathologies, such as post-traumatic stress disorder. CLINICAL TRIAL REGISTRATION NCT00504894.
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Affiliation(s)
- K O Pryor
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA Department of Anesthesia and Critical Care, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - J C Root
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA Department of Anesthesia and Critical Care, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - M Mehta
- Department of Anesthesia and Critical Care, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - E Stern
- Functional Neuroimaging Laboratory, Brigham and Women's Hospital, Harvard Medical School, 824 Boylston Street, Chestnut Hill, MA 02467, USA
| | - H Pan
- Functional Neuroimaging Laboratory, Brigham and Women's Hospital, Harvard Medical School, 824 Boylston Street, Chestnut Hill, MA 02467, USA
| | - R A Veselis
- Department of Anesthesia and Critical Care, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - D A Silbersweig
- Functional Neuroimaging Laboratory, Brigham and Women's Hospital, Harvard Medical School, 824 Boylston Street, Chestnut Hill, MA 02467, USA
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12
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Ji MH, Jia M, Zhang MQ, Liu WX, Xie ZC, Wang ZY, Yang JJ. Dexmedetomidine alleviates anxiety-like behaviors and cognitive impairments in a rat model of post-traumatic stress disorder. Prog Neuropsychopharmacol Biol Psychiatry 2014; 54:284-8. [PMID: 25004167 DOI: 10.1016/j.pnpbp.2014.06.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 06/23/2014] [Accepted: 06/29/2014] [Indexed: 11/17/2022]
Abstract
Post-traumatic stress disorder (PTSD) is a psychiatric disease that has substantial health implications, including high rates of health morbidity and mortality, as well as increased health-related costs. Although many pharmacological agents have proven the effects on the development of PTSD, current pharmacotherapies typically only produce partial improvement of PTSD symptoms. Dexmedetomidine is a selective, short-acting α2-adrenoceptor agonist, which has anxiolytic, sedative, and analgesic effects. We therefore hypothesized that dexmedetomidine possesses the ability to prevent the development of PTSD and alleviate its symptoms. By using the rat model of PTSD induced by five electric foot shocks followed by three weekly exposures to situational reminders, we showed that the stressed rats displayed pronounced anxiety-like behaviors and cognitive impairments compared to the controls. Notably, repeated administration of 20μg/kg dexmedetomidine showed impaired fear conditioning memory, decreased anxiety-like behaviors, and improved spatial cognitive impairments compared to the vehicle-treated stressed rats. These data suggest that dexmedetomidine may exert preventive and protective effects against anxiety-like behaviors and cognitive impairments in the rats with PTSD after repeated administration.
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Affiliation(s)
- Mu-Huo Ji
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Min Jia
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Ming-Qiang Zhang
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Wen-Xue Liu
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Zhong-Cong Xie
- Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Charlestown, MA, United States; Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Charlestown, MA, United States
| | - Zhong-Yun Wang
- Department of Anesthesiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
| | - Jian-Jun Yang
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China; Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, Xuzhou, China; Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou, China.
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Sedation agents differentially modulate cortical and subcortical blood oxygenation: evidence from ultra-high field MRI at 17.2 T. PLoS One 2014; 9:e100323. [PMID: 25050866 PMCID: PMC4106755 DOI: 10.1371/journal.pone.0100323] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/23/2014] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Sedation agents affect brain hemodynamic and metabolism leading to specific modifications of the cerebral blood oxygenation level. We previously demonstrated that ultra-high field (UHF) MRI detects changes in cortical blood oxygenation following the administration of sedation drugs commonly used in animal research. Here we applied the UHF-MRI method to study clinically relevant sedation drugs for their effects on cortical and subcortical (thalamus, striatum) oxygenation levels. METHODS We acquired T2*-weighted images of Sprague-Dawley rat brains at 17.2T in vivo. During each MRI session, rats were first anesthetized with isoflurane, then with a second sedative agent (sevoflurane, propofol, midazolam, medetomidine or ketamine-xylazine) after stopping isoflurane. We computed a T2*-oxygenation-ratio that aimed at estimating cerebral blood oxygenation level for each sedative agent in each region of interest: cortex, hippocampus, thalamus and striatum. RESULTS The T2*-oxygenation-ratio was consistent across scan sessions. This ratio was higher with inhalational agents than with intravenous agents. Under sevoflurane and medetomidine, T2*-oxygenation-ratio was homogenous across the brain regions. Intravenous agents (except medetomidine) induced a T2*-oxygenation-ratio imbalance between cortex and subcortical regions: T2*-oxygenation-ratio was higher in the cortex than the subcortical areas under ketamine-xylazine; T2*-oxygenation-ratio was higher in subcortical regions than in the cortex under propofol or midazolam. CONCLUSION Preclinical UHF MRI is a powerful method to monitor the changes in cerebral blood oxygenation level induced by sedative agents across brain structures. This approach also allows for a classification of sedative agents based on their differential effects on cerebral blood oxygenation level.
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Dexmedetomidine suppresses long-term potentiation in the hippocampal CA1 field of anesthetized rats. J Anesth 2014; 28:828-32. [PMID: 24854521 DOI: 10.1007/s00540-014-1853-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 05/08/2014] [Indexed: 10/25/2022]
Abstract
PURPOSE The aim of this study was to evaluate the effect of dexmedetomidine (DEX) on hippocampal synaptic activity in vivo. METHODS The adult rats used for this study received a intraperitoneal bolus injection of 3, 10, 30, or 100 μg/kg of DEX or an equivalent volume of saline. Electrophysiological recording of the hippocampal CA1 region was initiated 20 min after drug administration. The results are expressed as the percentages of the population spike amplitude measured just before high-frequency stimulation (HFS). The electrophysiological data were analyzed with an area under the curve (AUC) of 10-60 min after HFS. Moreover, to investigate the sedative dose of DEX in rats, we recorded the duration of loss of spontaneous movement after the administration of each dose of DEX. RESULTS Intraperitoneal administration of DEX at doses of 30 and 100 μg/kg induced a range of sedative effects. The AUC measurements were significantly lower in the 30 and 100 μg/kg groups than in those injected with vehicle (vehicle: 8.81 ± 0.49, n = 7; DEX 30 µg/kg: 6.02 ± 0.99, n = 6; DEX 100 µg/kg: 5.10 ± 0.43, n = 5; P < 0.05). CONCLUSION The results of our in vivo study reveal that sedative doses of DEX impaired the induction of hippocampal long-term potentiation (LTP). These findings may signify a causal link between DEX-induced sedative action and hippocampal LTP suppression, providing a better understanding of the mechanisms underlying the DEX-induced sedative and/or amnestic effect.
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Increased risk of awareness under anesthesia: an issue of consciousness or of memory? Anesthesiology 2014; 119:1236-8. [PMID: 24121216 DOI: 10.1097/aln.0000000000000024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Evolution of consciousness: phylogeny, ontogeny, and emergence from general anesthesia. Proc Natl Acad Sci U S A 2013; 110 Suppl 2:10357-64. [PMID: 23754370 DOI: 10.1073/pnas.1301188110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwin's insight and the recent "Cambridge Declaration on Consciousness in Non-Human Animals," a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.
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HWANG LAKKYONG, CHOI INYOUNG, KIM SUNGEUN, KO ILGYU, SHIN MALSOON, KIM CHANGJU, KIM SANGHOON, JIN JUNJANG, CHUNG JUNYOUNG, YI JAEWOO. Dexmedetomidine ameliorates intracerebral hemorrhage-induced memory impairment by inhibiting apoptosis and enhancing brain-derived neurotrophic factor expression in the rat hippocampus. Int J Mol Med 2013; 31:1047-56. [DOI: 10.3892/ijmm.2013.1301] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 03/08/2013] [Indexed: 11/06/2022] Open
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