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Obert DP, Killing D, Happe T, Tamas P, Altunkaya A, Dragovic SZ, Kreuzer M, Schneider G, Fenzl T. Substance specific EEG patterns in mice undergoing slow anesthesia induction. BMC Anesthesiol 2024; 24:167. [PMID: 38702608 PMCID: PMC11067159 DOI: 10.1186/s12871-024-02552-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 04/26/2024] [Indexed: 05/06/2024] Open
Abstract
The exact mechanisms and the neural circuits involved in anesthesia induced unconsciousness are still not fully understood. To elucidate them valid animal models are necessary. Since the most commonly used species in neuroscience are mice, we established a murine model for commonly used anesthetics/sedatives and evaluated the epidural electroencephalographic (EEG) patterns during slow anesthesia induction and emergence. Forty-four mice underwent surgery in which we inserted a central venous catheter and implanted nine intracranial electrodes above the prefrontal, motor, sensory, and visual cortex. After at least one week of recovery, mice were anesthetized either by inhalational sevoflurane or intravenous propofol, ketamine, or dexmedetomidine. We evaluated the loss and return of righting reflex (LORR/RORR) and recorded the electrocorticogram. For spectral analysis we focused on the prefrontal and visual cortex. In addition to analyzing the power spectral density at specific time points we evaluated the changes in the spectral power distribution longitudinally. The median time to LORR after start anesthesia ranged from 1080 [1st quartile: 960; 3rd quartile: 1080]s under sevoflurane anesthesia to 1541 [1455; 1890]s with ketamine. Around LORR sevoflurane as well as propofol induced a decrease in the theta/alpha band and an increase in the beta/gamma band. Dexmedetomidine infusion resulted in a shift towards lower frequencies with an increase in the delta range. Ketamine induced stronger activity in the higher frequencies. Our results showed substance-specific changes in EEG patterns during slow anesthesia induction. These patterns were partially identical to previous observations in humans, but also included significant differences, especially in the low frequencies. Our study emphasizes strengths and limitations of murine models in neuroscience and provides an important basis for future studies investigating complex neurophysiological mechanisms.
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Affiliation(s)
- David P Obert
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts's General Hospital, Boston, MA, 02114, USA
- Harvard Medical School, Boston, MA, 02115, USA
| | - David Killing
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Tom Happe
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Philipp Tamas
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Alp Altunkaya
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Srdjan Z Dragovic
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Matthias Kreuzer
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Gerhard Schneider
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany
| | - Thomas Fenzl
- School of Medicine and Health, Department of Anesthesiology and Intensive Care, Technical University of Munich, 81675, Munich, Germany.
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Liu C, Freeman DJ, Lammel S. Head-mounted central venous access during optical recordings and manipulations of neural activity in mice. Nat Protoc 2024; 19:960-983. [PMID: 38057625 PMCID: PMC10939862 DOI: 10.1038/s41596-023-00928-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 10/11/2023] [Indexed: 12/08/2023]
Abstract
Establishing reliable intravenous catheterization in mice with optical implants allows the combination of neural manipulations and recordings with rapid, time-locked delivery of pharmacological agents. Here we present a procedure for handmade jugular vein catheters designed for head-mounted intravenous access and provide surgical and postoperative guidance for improved survival and patency. A head-mounted vascular access point eliminates the need for a back-mounted button in animals already receiving neural implants, thereby reducing sites of implantation. This protocol, which is readily adoptable by experimenters with previous training and experience in mouse surgery, enables repeated fiber photometry recordings or optogenetic manipulation during drug delivery in adult mice that are awake and behaving, whether head fixed or freely moving. With practice, an experienced surgeon requires ~30 min to perform catheterization on each mouse. Altogether, these techniques facilitate the reliable and repeated delivery of pharmacological agents in mouse models while simultaneously recording at high temporal resolution and/or manipulating neural populations.
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Affiliation(s)
- Christine Liu
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
| | - Daniel J Freeman
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
| | - Stephan Lammel
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
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