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Beitchman JA, Krishna G, Bromberg CE, Thomas TC. Effects of isoflurane and urethane anesthetics on glutamate neurotransmission in rat brain using in vivo amperometry. BMC Neurosci 2023; 24:52. [PMID: 37817064 PMCID: PMC10563344 DOI: 10.1186/s12868-023-00822-3] [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: 03/16/2023] [Accepted: 09/19/2023] [Indexed: 10/12/2023] Open
Abstract
BACKGROUND Aspects of glutamate neurotransmission implicated in normal and pathological conditions are predominantly evaluated using in vivo recording paradigms in rats anesthetized with isoflurane or urethane. Urethane and isoflurane anesthesia influence glutamate neurotransmission through different mechanisms; however, real-time outcome measures of potassium chloride (KCl)-evoked glutamate overflow and glutamate clearance kinetics have not been compared within and between regions of the brain. In order to maintain rigor and reproducibility within the literature between the two most common methods of anesthetized in vivo recording of glutamate, we compared glutamate signaling as a function of anesthesia and brain region in the rat strain most used in neuroscience. METHODS In the following experiments, in vivo amperometric recordings of KCl-evoked glutamate overflow and glutamate clearance kinetics (uptake rate and T80) in the cortex, hippocampus, and thalamus were performed using glutamate-selective microelectrode arrays (MEAs) in young adult male, Sprague-Dawley rats anesthetized with either isoflurane or urethane. RESULTS Potassium chloride (KCl)-evoked glutamate overflow was similar under urethane and isoflurane anesthesia in all brain regions studied. Analysis of glutamate clearance determined that the uptake rate was significantly faster (53.2%, p < 0.05) within the thalamus under urethane compared to isoflurane, but no differences were measured in the cortex or hippocampus. Under urethane, glutamate clearance parameters were region-dependent, with significantly faster glutamate clearance in the thalamus compared to the cortex but not the hippocampus (p < 0.05). No region-dependent differences were measured for glutamate overflow using isoflurane. CONCLUSIONS These data support that amperometric recordings of KCl-evoked glutamate under isoflurane and urethane anesthesia result in similar and comparable data. However, certain parameters of glutamate clearance can vary based on choice of anesthesia and brain region. In these circumstances, special considerations are needed when comparing previous literature and planning future experiments.
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Affiliation(s)
- Joshua A Beitchman
- Department of Child Health, University of Arizona College of Medicine - Phoenix, 425 N. 5th St. | 322 ABC-1 Building, Phoenix, AZ, 85004-2127, USA
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix Children's Hospital, Phoenix, AZ, USA
- College of Graduate Studies, Midwestern University, Glendale, AZ, USA
| | - Gokul Krishna
- Department of Child Health, University of Arizona College of Medicine - Phoenix, 425 N. 5th St. | 322 ABC-1 Building, Phoenix, AZ, 85004-2127, USA
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Caitlin E Bromberg
- Department of Child Health, University of Arizona College of Medicine - Phoenix, 425 N. 5th St. | 322 ABC-1 Building, Phoenix, AZ, 85004-2127, USA
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Theresa Currier Thomas
- Department of Child Health, University of Arizona College of Medicine - Phoenix, 425 N. 5th St. | 322 ABC-1 Building, Phoenix, AZ, 85004-2127, USA.
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix Children's Hospital, Phoenix, AZ, USA.
- Phoenix VA Healthcare System, Phoenix, AZ, USA.
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Beitchman JA, Krishna G, Bromberg CE, Thomas TC. Effects of isoflurane and urethane anesthetics on glutamate neurotransmission in rat brain using in vivo amperometry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.16.528856. [PMID: 36824899 PMCID: PMC9949081 DOI: 10.1101/2023.02.16.528856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Aspects of glutamate neurotransmission implicated in normal and pathological conditions are often evaluated using in vivo recording paradigms in rats anesthetized with isoflurane or urethane. Urethane and isoflurane anesthesia influence glutamate neurotransmission through different mechanisms; however real-time outcome measures of potassium chloride (KCl)-evoked glutamate overflow and glutamate clearance kinetics have not been compared within and between regions of the brain. In the following experiments, in vivo amperometric recordings of KCl-evoked glutamate overflow and glutamate clearance kinetics (uptake rate and T80) in the cortex, hippocampus and thalamus were performed using glutamate-selective microelectrode arrays (MEAs) in young adult male, Sprague-Dawley rats anesthetized with isoflurane or urethane. Potassium chloride (KCl)-evoked glutamate overflow was similar under urethane and isoflurane anesthesia in all brain regions studied. Analysis of glutamate clearance determined that the uptake rate was significantly faster (53.2%, p<0.05) within the thalamus under urethane compared to isoflurane, but no differences were measured in the cortex or hippocampus. Under urethane, glutamate clearance parameters were region dependent, with significantly faster glutamate clearance in the thalamus compared to the cortex but not the hippocampus (p<0.05). No region dependent differences were measured for glutamate overflow using isoflurane. These data support that amperometric recordings of glutamate under isoflurane and urethane anesthesia result in mostly similar and comparable data. However, certain parameters of glutamate uptake vary based on choice of anesthesia and brain region. Special considerations must be given to these areas when considering comparison to previous literature and when planning future experiments.
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Affiliation(s)
- Joshua A. Beitchman
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
- College of Graduate Studies, Midwestern University, Glendale, AZ, USA
| | - Gokul Krishna
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Caitlin E. Bromberg
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Theresa Currier Thomas
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
- Phoenix VA Healthcare System, Phoenix, AZ, USA
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Castoldi V, d'Isa R, Marenna S, Comi G, Leocani L. Non-invasive visual evoked potentials under sevoflurane versus ketamine-xylazine in rats. Heliyon 2021; 7:e08360. [PMID: 34816047 PMCID: PMC8591496 DOI: 10.1016/j.heliyon.2021.e08360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/19/2021] [Accepted: 11/05/2021] [Indexed: 11/17/2022] Open
Abstract
Background Visual Evoked Potential (VEP) quantifies electrical signals produced in visual cortex in response to visual stimuli. VEP elicited by light flashes is a useful biomarker to evaluate visual function in preclinical models and it can be recorded in awake or anaesthetised state. Different types of anaesthesia influence VEP properties, such as latency, which measures the propagation speed along nerve fibers, and amplitude that quantifies the power of electrical signal. Aim The goal of this work is to compare VEPs elicited in Dark Agouti rats under two types of anaesthesia: volatile sevoflurane or injectable ketamine-xylazine. Methods VEP latency, amplitude, signal-to-noise ratio and recording duration were measured in Dark Agouti rats randomly assigned to two groups, the first subjected to volatile sevoflurane and the second to injectable ketamine-xylazine. Taking advantage of non-invasive flash-VEP recording through epidermal cup electrodes, three time points of VEP recordings were assessed in two weeks intervals. Results VEP recorded under ketamine-xylazine showed longer latency and higher amplitude compared with sevoflurane, with analogous repeatability over time. However, sevoflurane tended to suppress electrical signals from visual cortex, resulting in a lower signal-to-noise ratio. Moreover, VEP procedure duration lasted longer in rats anaesthetised with sevoflurane than ketamine-xylazine. Conclusions In Dark Agouti rats, the use of different anaesthesia can influence VEP components in terms of latency and amplitude. Notably, sevoflurane and ketamine-xylazine revealed satisfying repeatability over time, which is critical to perform reliable follow-up studies. Ketamine-xylazine allowed to obtain more clearly discernible VEP components and less background noise, together with a quicker recording procedure and a consequently improved animal safety and welfare.
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Affiliation(s)
- Valerio Castoldi
- Experimental Neurophysiology Unit, INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy
| | - Raffaele d'Isa
- Experimental Neurophysiology Unit, INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy
| | - Silvia Marenna
- Experimental Neurophysiology Unit, INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy
| | - Giancarlo Comi
- Vita-Salute San Raffaele University, Milan, Italy.,Casa di Cura del Policlinico, Milan, Italy
| | - Letizia Leocani
- Experimental Neurophysiology Unit, INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy
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Santangelo R, Castoldi V, D'Isa R, Marenna S, Huang SC, Cursi M, Comi G, Leocani L. Visual evoked potentials can be reliably recorded using noninvasive epidermal electrodes in the anesthetized rat. Doc Ophthalmol 2018; 136:165-175. [PMID: 29623523 DOI: 10.1007/s10633-018-9630-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/27/2018] [Indexed: 11/30/2022]
Abstract
PURPOSE Visual evoked potentials (VEPs) are a powerful tool to evaluate nervous conduction along the visual pathways, both in humans and in animal models. Traditionally, epidural screw electrodes are used to record VEPs in preclinical research. Here we tested the feasibility in the preclinical setting of the same noninvasive technique used for clinical VEP acquisition, by using epidermal cup electrodes with no surgical procedures. METHODS Monocular flash VEPs were recorded bilaterally under sevoflurane anesthesia once a week for 6 weeks in 14 dark Agouti rats, 7 with implanted epidural screws and 7 with epidermal 6 mm Ø Ag/AgCl cups. RESULTS VEP traces obtained with the two techniques were morphologically comparable. There were no significant differences in latency of the main visual component between screw-recorded VEPs (sVEPs) and cup-recorded VEPs (cVEPs). Amplitude values with epidermal cups were significantly lower than those with epidural screws. Both techniques provided latencies and amplitudes which were stable over time. Furthermore, with regard to latency both methods ensured highly repeatable measurements over time, with epidermal cups even providing slightly better results. On the other hand, considering amplitudes, cVEPs and sVEPs provided fairly acceptable repeatability. CONCLUSIONS Epidermal cup electrodes can provide comparable results to those obtained with the "gold standard" epidural screws, while representing a simpler and less invasive technique to test nervous conduction along the visual pathways in the preclinical setting.
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Affiliation(s)
- Roberto Santangelo
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Valerio Castoldi
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Raffaele D'Isa
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Silvia Marenna
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Su-Chun Huang
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Marco Cursi
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Giancarlo Comi
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Letizia Leocani
- Department of Neurology and Institute of Experimental Neurology (INSPE) - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy. .,University Vita-Salute San Raffaele - IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.
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Retinal Electrophysiology Is a Viable Preclinical Biomarker for Drug Penetrance into the Central Nervous System. J Ophthalmol 2016; 2016:5801826. [PMID: 27239335 PMCID: PMC4863103 DOI: 10.1155/2016/5801826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/10/2016] [Accepted: 03/16/2016] [Indexed: 01/19/2023] Open
Abstract
Objective. To examine whether retinal electrophysiology is a useful surrogate marker of drug penetrance into the central nervous system (CNS). Materials and Methods. Brain and retinal electrophysiology were assessed with full-field visually evoked potentials and electroretinograms in conscious and anaesthetised rats following systemic or local administrations of centrally penetrant (muscimol) or nonpenetrant (isoguvacine) compounds. Results. Local injections into the eye/brain bypassed the blood neural barriers and produced changes in retinal/brain responses for both drugs. In conscious animals, systemic administration of muscimol resulted in retinal and brain biopotential changes, whereas systemic delivery of isoguvacine did not. General anaesthesia confounded these outcomes. Conclusions. Retinal electrophysiology, when recorded in conscious animals, shows promise as a viable biomarker of drug penetration into the CNS. In contrast, when conducted under anaesthetised conditions confounds can be induced in both cortical and retinal electrophysiological recordings.
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Charng J, Nguyen CT, He Z, Dang TM, Vingrys AJ, Fish RL, Gurrell R, Brain P, Bui BV. Conscious wireless electroretinogram and visual evoked potentials in rats. PLoS One 2013; 8:e74172. [PMID: 24069276 PMCID: PMC3771909 DOI: 10.1371/journal.pone.0074172] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/29/2013] [Indexed: 11/24/2022] Open
Abstract
The electroretinogram (ERG, retina) and visual evoked potential (VEP, brain) are widely used in vivo tools assaying the integrity of the visual pathway. Current recordings in preclinical models are conducted under anesthesia, which alters neural physiology and contaminates responses. We describe a conscious wireless ERG and VEP recording platform in rats. Using a novel surgical technique to chronically implant electrodes subconjunctivally on the eye and epidurally over the visual cortex, we are able to record stable and repeatable conscious ERG and VEP signals over at least 1 month. We show that the use of anaesthetics, necessary for conventional ERG and VEP measurements, alters electrophysiology recordings. Conscious visual electrophysiology improves the viability of longitudinal studies by eliminating complications associated with repeated anaesthesia. It will also enable uncontaminated assessment of drug effects, allowing the eye to be used as an effective biomarker of the central nervous system.
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Affiliation(s)
- Jason Charng
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
| | - Christine T. Nguyen
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
| | - Zheng He
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
| | - Trung M. Dang
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
| | - Algis J. Vingrys
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
| | | | | | - Phil Brain
- Pfizer Global Research and Development, Kent, United Kingdom
| | - Bang V. Bui
- Department of Optometry & Vision Sciences, University of Melbourne, Victoria, Australia
- * E-mail:
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Suppression of Experimental Autoimmune Optic Neuritis by the Novel Agent Fingolimod. J Neuroophthalmol 2013; 33:143-8. [DOI: 10.1097/wno.0b013e31828ea2fc] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rogers B, Shih YYI, Garza BDL, Harrison JM, Roby J, Duong TQ. A low cost color visual stimulator for fMRI. J Neurosci Methods 2011; 204:379-82. [PMID: 22172916 DOI: 10.1016/j.jneumeth.2011.10.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 10/14/2011] [Accepted: 10/27/2011] [Indexed: 11/29/2022]
Abstract
This low cost visual stimulator was developed for use in small animal imaging. The stimulator uses a single tri-color LED for each eye and can output red, green, or blue light or any combination of the three. When all three LED colors are illuminated at the same time achromatic light is the output. The stimulator is almost entirely implemented in software with only minimal electronics. The LEDs are controlled via the parallel port of a desktop computer. Flicker frequency, wavelength, intensity and waveform shape are under software control. The LEDs are coupled to fiber optic cables which run into the MRI scanner room leaving the LEDs and the power source in the control room. Calibration with a radiometer shows the light output to be very linear from zero to full intensity. The stimulator was used in fMRI visual stimulation studies performed on Sprague Dawley rats with an 11.7Tesla magnet. As the stimulator is software driven, modifications to accommodate other protocols and extensions for new functionality can be readily incorporated. With this in mind, the visual stimulator circuit diagram and software including source code are available upon request.
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Affiliation(s)
- Bill Rogers
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX 78229, United States.
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Jehle T, Meschede W, Dersch R, Feltgen N, Bach M, Lagrèze W. Erythropoietin schützt retinale Ganglienzellen und die Sehfunktion nach Ischämie und Sehnervkompression im Rattenmodell. Ophthalmologe 2009; 107:347-53. [DOI: 10.1007/s00347-009-2030-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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