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Connell AR, Hookham MB, Fu D, Brazil DP, Lyons TJ, Yu JY. Comparisons of α2-Adrenergic Agents, Medetomidine and Xylazine, with Pentobarbital for Anesthesia: Important Pitfalls in Diabetic and Nondiabetic Rats. J Ocul Pharmacol Ther 2021; 38:156-166. [PMID: 34964655 PMCID: PMC8971989 DOI: 10.1089/jop.2021.0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Purpose: Anesthesia is necessary to conduct rodent electroretinograms (ERGs). We evaluated utility of the α2-agonist medetomidine versus xylazine for ERG studies in nondiabetic and diabetic rats. Pentobarbital was included as a comparator. Methods: Male Sprague-Dawley rats, with and without streptozotocin (STZ)-induced diabetes, were anesthetized with medetomidine (1 mg/kg), xylazine (10 mg/kg) (both with ketamine 75 mg/kg), or pentobarbital (70 mg/kg). The depth of anesthesia was assessed, and if adequate, scotopic ERGs were recorded. Blood glucose was monitored. Results: In nondiabetic rats, all three agents induced satisfactory anesthesia, but with differing durations: medetomidine > pentobarbital > xylazine. ERG responses were similar under medetomidine and xylazine, but relatively reduced under pentobarbital. Both α2-agonists (but not pentobarbital) elicited marked hyperglycemia (peak values 316.1 ± 42.6 and 300.3 ± 29.5 mg/dL, respectively), persisting for 12 h. In diabetic rats, elevated blood glucose concentrations were not affected by any of the agents, but the depth of anesthesia under medetomidine and xylazine was inadequate for ERG recording. Conclusions: In nondiabetic rats, medetomidine and xylazine elicited comparable effects on ERGs that differ from pentobarbital, but both perturbed glucose metabolism, potentially confounding experimental outcomes. In STZ-diabetic rats, neither α2-agent provided adequate anesthesia, while pentobarbital did so. Problems with α2-anesthetic agents, including medetomidine, must be recognized to ensure meaningful interpretation of experimental results.
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Affiliation(s)
- Anna R Connell
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Michelle B Hookham
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Dongxu Fu
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.,Division of Endocrinology, Diabetes, and Metabolic Diseases, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.,Diabetes Free South Carolina, BlueCross BlueShield of South Carolina, Columbia, South Carolina, USA
| | - Derek P Brazil
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom
| | - Timothy J Lyons
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.,Division of Endocrinology, Diabetes, and Metabolic Diseases, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.,Diabetes Free South Carolina, BlueCross BlueShield of South Carolina, Columbia, South Carolina, USA
| | - Jeremy Y Yu
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.,Division of Endocrinology, Diabetes, and Metabolic Diseases, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
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Loizzo S, Rimondini R, Campana G, Fortuna A, Maroccia Z, Martorana A, Koch G. C57BL/6J and DBA/2J strains present opposite sex differences in flash visual evoked potential latency: A possible confusing factor in gender studies on neurological diseases' transgenic models. Brain Res Bull 2021; 176:18-24. [PMID: 34391824 DOI: 10.1016/j.brainresbull.2021.08.005] [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: 05/07/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
The cholinergic neurotransmitter system in the brain is crucial in processing information related to cognitive, behavioral, and motor functions. A cholinergic dysfunction has been correctly described as one of the primary causes of neurodegenerative diseases. Differences in levels of acetylcholine or expression and function of receptors in selected brain areas have been indicated as one of the causes of sexual dimorphism in neurotransmission. However, variability in results among studies based on different mice strains could affect conclusions on this topic. Visual evoked potentials (VEPs) of male and female DBA/2J and C57BL/6J mice, which are two of the most common strains backgrounds in use for developing transgenic mice models of neurological diseases, have been studied. Effects induced by a single low dose of physostigmine have also been performed to evaluate the cholinergic system involvement. VEPs responses to luminous stimuli in C57BL/6J mice have shown a consistently lower latency than in DBA/2J, confirming the previous observation of strain differences in cholinergic function. Interestingly, strains present an opposite-sex difference in VEP latency not apparently related to sensitivity to physostigmine. These findings point at paying extreme attention to the choice of the genetic background of the animal model, especially in those basic and pre-clinical experiments that involve visual functioning.
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Affiliation(s)
- Stefano Loizzo
- Department of Cardiovascular, Endocrine-Metabolic and Ageing-Associated Diseases, Istituto Superiore di Sanità, Rome, Italy.
| | - Roberto Rimondini
- Department of Medical and Clinical Sciences, University of Bologna, Bologna, Italy
| | - Gabriele Campana
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Andrea Fortuna
- Department of Cardiovascular, Endocrine-Metabolic and Ageing-Associated Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Zaira Maroccia
- Department of Cardiovascular, Endocrine-Metabolic and Ageing-Associated Diseases, Istituto Superiore di Sanità, Rome, Italy
| | | | - Giacomo Koch
- Non-Invasive Brain Stimulation Unit, Department of Behavioral and Clinical Neurology, Santa Lucia Foundation, Rome, Italy
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d'Isa R, Castoldi V, Marenna S, Santangelo R, Comi G, Leocani L. A new electrophysiological non-invasive method to assess retinocortical conduction time in the Dark Agouti rat through the simultaneous recording of electroretinogram and visual evoked potential. Doc Ophthalmol 2020; 140:245-255. [PMID: 31832898 DOI: 10.1007/s10633-019-09741-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/06/2019] [Indexed: 11/25/2022]
Abstract
PURPOSE To develop a non-invasive method exploiting simultaneous recording of epidermal visual evoked potential (VEP) and epicorneal electroretinogram (ERG) to study retinocortical function and to evaluate its reliability and repeatability over time. METHODS Female wild-type DA rats were anesthetized with ketamine/xylazine (40/5 mg/kg). Epidermal VEP (Ag/AgCl cup electrode on scalp) and epicorneal ERG (gold ring electrode on eye surface) were recorded simultaneously in response to flash stimulation. RESULTS ANOVA for repeated measures showed that peak times of ERG b-wave and of VEP N1 and P2 were stable across 6 weekly time-points, as well as the corresponding amplitudes. Mean retinocortical time from b-wave to N1 (RCT1) was 7.6 ms and remained comparable across the 6 time-points. Mean retinocortical time from b-wave to P2 (RCT2) was 28.7 ms and did not show significant variations over time. Coefficient of variation (CoV%) and CoV% adjusted for sample size, namely relative standard error (RSE%), were calculated as indexes of repeatability. Good RSE% over time was obtained (< 5% for b-wave, N1 and P2 peak times; < 20% and < 7% for RCT1 and RCT2, respectively). CONCLUSIONS Simultaneous recording of ERG and VEP has been previously achieved through invasive methods requiring surgery. Here, we present a new non-invasive method, which allowed to obtain peak and retinocortical times that were constant across a long period and had a good repeatability over time. This method will ensure not only a gain in animal welfare, but will also avoid stress and eye or brain lesions which can interfere with experimental variables.
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Affiliation(s)
- Raffaele d'Isa
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
| | - Valerio Castoldi
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Silvia Marenna
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Roberto Santangelo
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Giancarlo Comi
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy
| | - Letizia Leocani
- Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy.
- Vita-Salute San Raffaele University, Via Olgettina 58, 20132, Milan, Italy.
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Matteucci A, Ricceri L, Fabbri A, Fortuna A, Travaglione S, Guidotti M, Martinelli A, Villa M, Pricci F, Maroccia Z, Campana G, Malchiodi-Albedi F, Fiorentini C, Loizzo S. Eye Drop Instillation of the Rac1 Modulator CNF1 Attenuates Retinal Gliosis and Ameliorates Visual Performance in a Rat Model of Hypertensive Retinopathy. Neuroscience 2019; 411:119-129. [PMID: 31128161 DOI: 10.1016/j.neuroscience.2019.05.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 12/15/2022]
Abstract
In hypertensive retinopathy, the retinal damage due to high blood pressure is accompanied by increased expression of Glial Fibrillary Acidic Protein (GFAP), which indicates a role of neuroinflammatory processes in such a retinopathy. Proteins belonging to the Rho GTPase family, particularly Rac1, are involved in the activation of Müller glia and in the progression of photoreceptor degeneration, and may thus represent a novel candidate for therapeutic intervention following central nervous system inflammation. In this paper, we have observed that topical administration as eye drops of Cytotoxic Necrotizing Factor 1 (CNF1), a Rho GTPase modulator, surprisingly improves electrophysiological and behavioral visual performances in aged spontaneously hypertensive rats. Furthermore, such functional improvement is accompanied by a reduction of Rac1 activity and retinal GFAP expression. Our results suggest that Rac1 inhibition through CNF1 topical administration may represent a new strategy to target retinal gliosis.
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Affiliation(s)
- Andrea Matteucci
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Laura Ricceri
- Centre for Behavioural Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Alessia Fabbri
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Andrea Fortuna
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Sara Travaglione
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Marco Guidotti
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Andrea Martinelli
- National Centre for Animal Research and Welfare, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Marika Villa
- Department of Cardiovascular, Dysmetabolic and Endocrine-Metabolic Diseases, and Ageing, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Flavia Pricci
- Department of Cardiovascular, Dysmetabolic and Endocrine-Metabolic Diseases, and Ageing, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Zaira Maroccia
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Gabriele Campana
- Department of Pharmacy and Biotechnology, University of Bologna, Via Zamboni, 33, Bologna, Italy
| | - Fiorella Malchiodi-Albedi
- Centre for Behavioural Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Carla Fiorentini
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy; Association for Research on Integrative Oncology Therapies (ARTOI), Rome, Italy
| | - Stefano Loizzo
- Italian Center for Global Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
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Nguyen CTO, Hui F, Charng J, Velaedan S, van Koeverden AK, Lim JKH, He Z, Wong VHY, Vingrys AJ, Bui BV, Ivarsson M. Retinal biomarkers provide "insight" into cortical pharmacology and disease. Pharmacol Ther 2017; 175:151-177. [PMID: 28174096 DOI: 10.1016/j.pharmthera.2017.02.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The retina is an easily accessible out-pouching of the central nervous system (CNS) and thus lends itself to being a biomarker of the brain. More specifically, the presence of neuronal, vascular and blood-neural barrier parallels in the eye and brain coupled with fast and inexpensive methods to quantify retinal changes make ocular biomarkers an attractive option. This includes its utility as a biomarker for a number of cerebrovascular diseases as well as a drug pharmacology and safety biomarker for the CNS. It is a rapidly emerging field, with some areas well established, such as stroke risk and multiple sclerosis, whereas others are still in development (Alzheimer's, Parkinson's, psychological disease and cortical diabetic dysfunction). The current applications and future potential of retinal biomarkers, including potential ways to improve their sensitivity and specificity are discussed. This review summarises the existing literature and provides a perspective on the strength of current retinal biomarkers and their future potential.
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Affiliation(s)
- Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia.
| | - Flora Hui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Jason Charng
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Shajan Velaedan
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Anna K van Koeverden
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Jeremiah K H Lim
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Magnus Ivarsson
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
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Cavero I, Holzgrefe H. 15 th Annual Meeting of the Safety Pharmacology Society: Focus on traditional sensory systems. J Pharmacol Toxicol Methods 2016; 83:55-71. [PMID: 27659846 DOI: 10.1016/j.vascn.2016.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/30/2016] [Accepted: 09/14/2016] [Indexed: 12/12/2022]
Abstract
INTRODUCTION This report summarizes and comments key talks on the five traditional senses (ear, vestibular system, vision, taste, olfaction, and touch) which were delivered during the 2015 Annual Meeting of the Safety Pharmacology (SP) Society. AREAS COVERED The functional observational battery (FOB) can detect major candidate drug liabilities only on ear, touch and vision. Anatomy, physiology, pharmacology, and pathology notions on each sensory system introduce speaker talks. Techniques for evaluating drug effects on hearing functions are reviewed. Nonclinical approaches to assess vestibular toxicity leading to balance deficits are presented. Retinal explants studied with multielectrode arrays allow the identification of drug liability sites on the retina. Routinely performed Safety Pharmacology assays are not powered to address candidate drug-induced disturbances on taste and smell. This weakness needs correction since unintended pharmacological impairment of these sensorial functions may have serious health consequences. Neuropathy produced by chemotherapeutic agents may cause multiple sensorial perception distortions. CONCLUSIONS Safety Pharmacology studies should ensure the safety of any candidate drug on the five sensorial systems.
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Sergeeva EG, Henrich-Noack P, Gorkin AG, Sabel BA. Preclinical model of transcorneal alternating current stimulation in freely moving rats. Restor Neurol Neurosci 2016; 33:761-9. [PMID: 25813371 DOI: 10.3233/rnn-150513] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Transcorneal alternating current stimulation (tACS) has become a promising tool to modulate brain functions and treat visual diseases. To understand the mechanisms of action a suitable animal model is required. However, because existing animal models employ narcosis, which interferes with brain oscillations and stimulation effects, we developed an experimental setup where current stimulation via the eye and flicker light stimulation can be applied while simultaneously recording local field potentials in awake rats. METHOD tACS was applied in freely-moving rats (N = 24) which had wires implanted under their upper eye lids. Field potential recordings were made in visual cortex and superior colliculus. To measure visual evoked responses, rats were exposed to flicker-light using LEDs positioned in headset spectacles. RESULTS Corneal electrodes and recording assemblies were reliably operating and well tolerated for at least 4 weeks. Transcorneal stimulation without narcosis did not induce any adverse reactions. Stable head stages allowed repetitive and long-lasting recordings of visual and electrically evoked potentials in freely moving animals. Shape and latencies of electrically evoked responses measured in the superior colliculus and visual cortex indicate that specific physiological responses could be recorded after tACS. CONCLUSIONS Our setup allows the stimulation of the visual system in unanaesthetised rodents with flicker light and transcorneally applied current travelling along the physiological signalling pathway. This methodology provides the experimental basis for further studies of recovery and restoration of vision.
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Affiliation(s)
- Elena G Sergeeva
- Institute of Medical Psychology, Medical Faculty, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Petra Henrich-Noack
- Institute of Medical Psychology, Medical Faculty, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | | | - Bernhard A Sabel
- Institute of Medical Psychology, Medical Faculty, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
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Measurement of Electroretinograms and Visually Evoked Potentials in Awake Moving Mice. PLoS One 2016; 11:e0156927. [PMID: 27257864 PMCID: PMC4892628 DOI: 10.1371/journal.pone.0156927] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/20/2016] [Indexed: 11/19/2022] Open
Abstract
The development of new treatments for intractable retinal diseases requires reliable functional assessment tools for animal models. In vivo measurements of neural activity within visual pathways, including electroretinogram (ERG) and visually evoked potential (VEP) recordings, are commonly used for such purposes. In mice, the ERG and VEPs are usually recorded under general anesthesia, a state that may alter sensory transduction and neurotransmission, but seldom in awake freely moving mice. Therefore, it remains unknown whether the electrophysiological assessment of anesthetized mice accurately reflects the physiological function of the visual pathway. Herein, we describe a novel method to record the ERG and VEPs simultaneously in freely moving mice by immobilizing the head using a custom-built restraining device and placing a rotatable cylinder underneath to allow free running or walking during recording. Injection of the commonly used anesthetic mixture xylazine plus ketamine increased and delayed ERG oscillatory potentials by an average of 67.5% and 36.3%, respectively, compared to unanesthetized mice, while having minimal effects on the a-wave and b-wave. Similarly, components of the VEP were enhanced and delayed by up to 300.2% and 39.3%, respectively, in anesthetized mice. Our method for electrophysiological recording in conscious mice is a sensitive and robust means to assess visual function. It uses a conventional electrophysiological recording system and a simple platform that can be built in any laboratory at low cost. Measurements using this method provide objective indices of mouse visual function with high precision and stability, unaffected by anesthetics.
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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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Vallone F, Lai S, Spalletti C, Panarese A, Alia C, Micera S, Caleo M, Di Garbo A. Post-Stroke Longitudinal Alterations of Inter-Hemispheric Correlation and Hemispheric Dominance in Mouse Pre-Motor Cortex. PLoS One 2016; 11:e0146858. [PMID: 26752066 PMCID: PMC4709093 DOI: 10.1371/journal.pone.0146858] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/21/2015] [Indexed: 11/19/2022] Open
Abstract
Purpose Limited restoration of function is known to occur spontaneously after an ischemic injury to the primary motor cortex. Evidence suggests that Pre-Motor Areas (PMAs) may “take over” control of the disrupted functions. However, little is known about functional reorganizations in PMAs. Forelimb movements in mice can be driven by two cortical regions, Caudal and Rostral Forelimb Areas (CFA and RFA), generally accepted as primary motor and pre-motor cortex, respectively. Here, we examined longitudinal changes in functional coupling between the two RFAs following unilateral photothrombotic stroke in CFA (mm from Bregma: +0.5 anterior, +1.25 lateral). Methods Local field potentials (LFPs) were recorded from the RFAs of both hemispheres in freely moving injured and naïve mice. Neural signals were acquired at 9, 16 and 23 days after surgery (sub-acute period in stroke animals) through one bipolar electrode per hemisphere placed in the center of RFA, with a ground screw over the occipital bone. LFPs were pre-processed through an efficient method of artifact removal and analysed through: spectral,cross-correlation, mutual information and Granger causality analysis. Results Spectral analysis demonstrated an early decrease (day 9) in the alpha band power in both the RFAs. In the late sub-acute period (days 16 and 23), inter-hemispheric functional coupling was reduced in ischemic animals, as shown by a decrease in the cross-correlation and mutual information measures. Within the gamma and delta bands, correlation measures were already reduced at day 9. Granger analysis, used as a measure of the symmetry of the inter-hemispheric causal connectivity, showed a less balanced activity in the two RFAs after stroke, with more frequent oscillations of hemispheric dominance. Conclusions These results indicate robust electrophysiological changes in PMAs after stroke. Specifically, we found alterations in transcallosal connectivity, with reduced inter-hemispheric functional coupling and a fluctuating dominance pattern. These reorganizations may underlie vicariation of lost functions following stroke.
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Affiliation(s)
- Fabio Vallone
- Institute of Biophysics, CNR, Pisa, Italy
- Translational Neural Engineering Area, The Biorobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Stefano Lai
- Translational Neural Engineering Area, The Biorobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Cristina Spalletti
- Neuroscience Institute, CNR, Pisa, Italy
- Life Science Institute, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Alessandro Panarese
- Translational Neural Engineering Area, The Biorobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy
| | | | - Silvestro Micera
- Translational Neural Engineering Area, The Biorobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy
- Bertarelli Foundation Chair in Translational Neuroengineering Center for Neuroprosthetics and Institute of Bioengineering School of Engineering Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
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Travaglione S, Ballan G, Fortuna A, Ferri A, Guidotti M, Campana G, Fiorentini C, Loizzo S. CNF1 Enhances Brain Energy Content and Counteracts Spontaneous Epileptiform Phenomena in Aged DBA/2J Mice. PLoS One 2015; 10:e0140495. [PMID: 26457896 PMCID: PMC4601759 DOI: 10.1371/journal.pone.0140495] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 09/25/2015] [Indexed: 11/19/2022] Open
Abstract
Epilepsy, one of the most common conditions affecting the brain, is characterized by neuroplasticity and brain cell energy defects. In this work, we demonstrate the ability of the Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1) to counteract epileptiform phenomena in inbred DBA/2J mice, an animal model displaying genetic background with an high susceptibility to induced- and spontaneous seizures. Via modulation of the Rho GTPases, CNF1 regulates actin dynamics with a consequent increase in spine density and length in pyramidal neurons of rat visual cortex, and influences the mitochondrial homeostasis with remarkable changes in the mitochondrial network architecture. In addition, CNF1 improves cognitive performances and increases ATP brain content in mouse models of Rett syndrome and Alzheimer's disease. The results herein reported show that a single dose of CNF1 induces a remarkable amelioration of the seizure phenotype, with a significant augmentation in neuroplasticity markers and in cortex mitochondrial ATP content. This latter effect is accompanied by a decrease in the expression of mitochondrial fission proteins, suggesting a role of mitochondrial dynamics in the CNF1-induced beneficial effects on this epileptiform phenotype. Our results strongly support the crucial role of brain energy homeostasis in the pathogenesis of certain neurological diseases, and suggest that CNF1 could represent a putative new therapeutic tool for epilepsy.
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Affiliation(s)
- Sara Travaglione
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
| | - Giulia Ballan
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
| | - Andrea Fortuna
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
| | - Alberto Ferri
- Institute of Cellular Biology and Neurobiology, CNR, Via del Fosso di Fiorano 64/65, 00143, Roma, Italy
| | - Marco Guidotti
- Department of Veterinary Public Health and Food Safety, Viale Regina Elena 299, 00161, Roma, Italy
| | - Gabriele Campana
- Department of Pharmacy and Biotechnology, University of Bologna, Via Irnerio 48, 40126, Bologna, Italy
| | - Carla Fiorentini
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
| | - Stefano Loizzo
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
- * E-mail:
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12
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Palladino G, Loizzo S, Fortuna A, Canterini S, Palombi F, Erickson RP, Mangia F, Fiorenza MT. Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin. Orphanet J Rare Dis 2015; 10:133. [PMID: 26458950 PMCID: PMC4603821 DOI: 10.1186/s13023-015-0348-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 09/27/2015] [Indexed: 12/21/2022] Open
Abstract
Background The lysosomal storage disorder, Niemann Pick type C1 (NPC1), presents a variable phenotype including neurovisceral and neurological symptoms. 2-Hydroxypropyl-ß-cyclodextrin (HPßCD)-based therapies are presently the most promising route of intervention. While severe cerebellar dysfunction remains the main disabling feature of NPC1, sensory functions including auditory and olfactory ones are also affected. Morphological and functional anomalies of Npc1−/− mouse retina have also been observed, although the functional integrity of the visual pathway from retina to visual cortex is still unsettled. We have addressed this issue by characterizing the visual evoked potential (VEP) response of Npc1−/− mice and determining if/how HPßCD administration influences the VEPs of both Npc1−/− and Npc1+/+ mice. Methods VEP elicited by a brief visual stimulus were recorded from the scalp overlying the visual cortex of adult (PN, postnatal days 60, 75, 85 and 100) Npc1+/+ and Npc1−/− mice that had received repeated injections of either HPßCD or plain vehicle. The first injection was given at PN4 and was followed by a second one at PN7 and thereafter by weekly injections up to PN49. Cholesterol accumulation and myelin loss were finally assessed by filipin staining and myelin basic protein immunohistochemistry, respectively. Results and discussion We have found that the transmission of visual signals from retina to visual cortex is negatively influenced by the loss of Npc1 function. In fact, the VEP response of Npc1−/− mice displayed a highly significant increase in the latency compared to that of Npc1+/+ mice. HPßCD administration fully rescued this defect and counteracted the cholesterol accumulation in retinal ganglion cells and dorsal lateral geniculate nucleus neurons, as well as the myelin loss in optic nerve fibers and axons projecting to the visual cortex observed in of Npc1−/− mice. By contrast, HPßCD administration had no effect on the VEP response of Npc1+/+ mice, further strengthening the treatment efficacy. Conclusions This study pinpoints the analysis of VEP response as a potentially accurate and non-invasive approach to assess neural activity and visual information processing in NPC1 patients, as well as for monitoring the progression of the disease and assessing the efficacy of potential therapies. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0348-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Giampiero Palladino
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Stefano Loizzo
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, via Regina Elena 299, 00161, Rome, Italy
| | - Andrea Fortuna
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, via Regina Elena 299, 00161, Rome, Italy
| | - Sonia Canterini
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Fioretta Palombi
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161, Rome, Italy
| | - Robert P Erickson
- Department of Pediatrics, University of Arizona, Tucson, AZ, 85724-5073, USA
| | - Franco Mangia
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy
| | - Maria Teresa Fiorenza
- Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, 00185, Rome, Italy.
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13
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Brandli A, Stone J. Using the Electroretinogram to Assess Function in the Rodent Retina and the Protective Effects of Remote Limb Ischemic Preconditioning. J Vis Exp 2015:e52658. [PMID: 26131649 DOI: 10.3791/52658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The ERG is the sum of all retinal activity. The ERG is usually recorded from the cornea, which acts as an antenna that collects and sums signals from the retina. The ERG is a sensitive measure of changes in retinal function that are pan-retinal, but is less effective for detecting damage confined to a small area of retina. In the present work we describe how to record the 'flash' ERG, which is the potential generated when the retina is exposed to a brief light flash. We describe methods of anaesthesia, mydriasis and corneal management during recording; how to keep the retina dark adapted; electrode materials and placement; the range and calibration of stimulus energy; recording parameters and the extraction of data. We also describe a method of inducing ischemia in one limb, and how to use the ERG to assess the effects of this remote-from-the-retina ischemia on retinal function after light damage. A two-flash protocol is described which allows isolation of the cone-driven component of the dark-adapted ERG, and thereby the separation of the rod and cone components. Because it can be recorded with techniques that are minimally invasive, the ERG has been widely used in studies of the physiology, pharmacology and toxicology of the retina. We describe one example of this usefulness, in which the ERG is used to assess the function of the light-damaged retina, with and without a neuroprotective intervention; preconditioning by remote ischemia.
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Affiliation(s)
- Alice Brandli
- Discipline of Physiology and Bosch Institute, Sydney Medical School, University of Sydney;
| | - Jonathan Stone
- Discipline of Physiology and Bosch Institute, Sydney Medical School, University of Sydney
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14
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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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15
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Loizzo A, Spampinato SM, Campana G, Vella S, Fortuna A, Costa L, Capasso A, Monteleone P, Renzi P, Loizzo S. Enhanced brain performance in mice following postnatal stress. J Endocrinol 2012; 215:413-24. [PMID: 23045190 DOI: 10.1530/joe-12-0369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The double postnatal stress model (brief maternal separation plus sham injection daily applied from birth to weaning) induces metabolic alterations similar to type 2 diabetes in young-adult male mice. We verify whether 1) the stress also induces brain metabolic-functional alterations connected to diabetes and 2) different alterations are modulated selectively by two stress-damaged endogenous systems (opioid- and/or ACTH-corticosteroid-linked). Here, diabetes-like metabolic plus neurophysiologic-neurometabolic parameters are studied in adult mice following postnatal stress and drug treatment. Surprisingly, together with 'classic' diabetes-like alterations, the stress model induces in young-adult mice significantly enhanced brain neurometabolic-neurophysiologic performances, consisting of decreased latency to flash-visual evoked potentials (- ~8%); increased level (+ ~40%) and reduced latency (- ~30%) of NAD(P)H autofluorescence postsynaptic signals following electric stimuli; enhanced passive avoidance learning (+ ~135% latency); and enhanced brain-derived neurotrophic factor level (+ ~70%). Postnatal treatment with the opioid receptor antagonist naloxone prevents some alterations, moreover the treatment with antisense (AS; AS vs proopiomelanocortin mRNA) draws all parameters to control levels, thus showing that some alterations are bound to endogenous opioid-system hyper-functioning, while others depend on ACTH-corticosterone system hyper-functioning. Our stress model induces diabetes-like metabolic alterations coupled to enhanced brain neurometabolic-neurophysiologic performances. Taken all together, these findings are compatible with an 'enduring acute-stress' reaction, which puts mice in favorable survival situations vs controls. However, prolonged hormonal-metabolic imbalances are expected to also produce diabetes-like complications at later ages in stressed mice.
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Affiliation(s)
- Alberto Loizzo
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanita', via Regina Elena 299, 00161 Rome, Italy
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Andermann ML, Kerlin AM, Roumis DK, Glickfeld LL, Reid RC. Functional specialization of mouse higher visual cortical areas. Neuron 2012; 72:1025-39. [PMID: 22196337 DOI: 10.1016/j.neuron.2011.11.013] [Citation(s) in RCA: 285] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
Abstract
The mouse is emerging as an important model for understanding how sensory neocortex extracts cues to guide behavior, yet little is known about how these cues are processed beyond primary cortical areas. Here, we used two-photon calcium imaging in awake mice to compare visual responses in primary visual cortex (V1) and in two downstream target areas, AL and PM. Neighboring V1 neurons had diverse stimulus preferences spanning five octaves in spatial and temporal frequency. By contrast, AL and PM neurons responded best to distinct ranges of stimulus parameters. Most strikingly, AL neurons preferred fast-moving stimuli while PM neurons preferred slow-moving stimuli. By contrast, neurons in V1, AL, and PM demonstrated similar selectivity for stimulus orientation but not for stimulus direction. Based on these findings, we predict that area AL helps guide behaviors involving fast-moving stimuli (e.g., optic flow), while area PM helps guide behaviors involving slow-moving objects.
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Affiliation(s)
- Mark L Andermann
- Department of Neurobiology, Harvard Medical School, Goldenson 243, 220 Longwood Avenue, Boston, MA 02115, USA
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Jehle T, Ehlken D, Wingert K, Feuerstein TJ, Bach M, Lagrèze WA. Influence of narcotics on luminance and frequency modulated visual evoked potentials in rats. Doc Ophthalmol 2009; 118:217-24. [DOI: 10.1007/s10633-008-9160-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 12/08/2008] [Indexed: 11/29/2022]
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