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Leterme G, Guigou C, Oudot A, Collin B, Boudon J, Millot N, Geissler A, Belharet K, Bozorg Grayeli A. Superparamagnetic Nanoparticle Delivery to the Cochlea Through Round Window by External Magnetic Field: Feasibility and Toxicity. Surg Innov 2019; 26:646-655. [PMID: 31478462 DOI: 10.1177/1553350619867217] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Introduction. The objective of this study was to evaluate the feasibility and toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) administered into the cochlea through the round window (RW) by an external magnetic field. Materials and Methods. In 5 Wistar rats, the left RW was punctured. SPIONs suspended in hyaluronic gel (5 mg/mL) were applied in the RW niche and covered by a muscle graft. The nanoparticles were mobilized using a rare earth magnet (0.54 T) held in 4 consecutive positions around the head. The right ear served as control. Hearing function was monitored by auditory brainstem responses (4-32 kHz tone bursts). Results. The auditory thresholds remained unchanged 1 month after the administration. The histological study of the cochleae showed that SPIONs were driven into the scala tympani in the basal turn, the second turn, and the apex. Conclusion. Superparamagnetic nanoparticles can be driven inside the cochlea toward the apex with a preserved hearing up to 1 month in rats.
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Affiliation(s)
- Gaëlle Leterme
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
| | - Caroline Guigou
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
| | | | - Bertrand Collin
- Centre Georges François Leclerc, Dijon, France.,ICMUB, UMR 6302 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Julien Boudon
- Laboratoire ICB, UMR 6303 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Nadine Millot
- Laboratoire ICB, UMR 6303 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Audrey Geissler
- Plateforme d'imagerie cellulaire CellImaP, Université Bourgogne-Franche-Comté, Dijon, France
| | - Karim Belharet
- Laboratoire PRISME, HEI Campus Centre, Châteauroux, France
| | - Alexis Bozorg Grayeli
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
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Chang MY, Park MK, Park SH, Suh MW, Lee JH, Oh SH. Surgical Labyrinthectomy of the Rat to Study the Vestibular System. J Vis Exp 2018. [PMID: 29863682 DOI: 10.3791/57681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including surgical or chemical labyrinthectomy and vestibular neurectomy. Surgical labyrinthectomy is a relatively simple, reliable, and rapid method. Here, we describe the surgical technique for rat labyrinthectomy. A postauricular incision is made under general anesthesia to expose the external auditory canal and the tympanic membrane, after which the tympanic membrane and the ossicles are removed without the stapes. The stapes artery, which is located between the stapes and the oval window, is a vulnerable structure and must be preserved to obtain a clear surgical field. A hole to fenestrate the vestibule is made with a 2.1-mm drill bur superior to the stapes. Then, 100% ethanol is injected through this hole and aspirated several times. Meticulous dissection under a microscope and careful bleeding control are essential to obtain reliable results. Symptoms of vestibular loss, such as nystagmus, head tilting, and a rolling motion, are seen immediately after surgery. The rotarod or rotation chair test can be used to objectively and quantitatively evaluate the vestibular function.
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Affiliation(s)
- Mun Young Chang
- Department of Otolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine
| | - Moo Kyun Park
- Department of Otolaryngology-Head and Neck Surgery, Seoul National University Hospital;
| | - So Hyeon Park
- Department of Otolaryngology-Head and Neck Surgery, Seoul National University Hospital
| | - Myung-Whan Suh
- Department of Otolaryngology-Head and Neck Surgery, Seoul National University Hospital
| | - Jun Ho Lee
- Department of Otolaryngology-Head and Neck Surgery, Seoul National University Hospital
| | - Seung Ha Oh
- Department of Otolaryngology-Head and Neck Surgery, Seoul National University Hospital
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Kong TH, Yu S, Jung B, Choi JS, Seo YJ. Monitoring blood-flow in the mouse cochlea using an endoscopic laser speckle contrast imaging system. PLoS One 2018; 13:e0191978. [PMID: 29489849 PMCID: PMC5830291 DOI: 10.1371/journal.pone.0191978] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 01/15/2018] [Indexed: 12/18/2022] Open
Abstract
Laser speckle contrast imaging (LSCI) enables continuous high-resolution assessment of microcirculation in real-time. We applied an endoscope to LSCI to measure cochlear blood-flow in an ischemia–reperfusion mouse model. We also explored whether using xenon light in combination with LSCI facilitates visualization of anatomical position. Based on a previous preliminary study, the appropriate wavelength for penetrating the thin bony cochlea was 830 nm. A 2.7-mm-diameter endoscope was used, as appropriate for the size of the mouse cochlea. Our endoscopic LSCI system was used to illuminate the right cochlea after dissection of the mouse. We observed changes in the speckle signals when we applied the endoscopic LSCI system to the ischemia-reperfusion mouse model. The anatomical structure of the mouse cochlea and surrounding structures were clearly visible using the xenon light. The speckle signal of the cochlea was scattered, with an intensity that varied between that of the stapes (with the lowest signal), the negative control, and the stapedial artery (with the highest signal), the positive control. In the cochlear ischemia–reperfusion mouse model, the speckle signal of the cochlea decreased during the ischemic phase, and increased during the reperfusion phase, clearly reflecting cochlear blood-flow. The endoscopic LSCI system generates high-resolution images in real-time, allowing visualization of blood-flow and its changes in the mouse cochlea. Anatomical structures were clearly matched using LSCI along with visible light.
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Affiliation(s)
- Tae Hoon Kong
- Department of Otorhinolaryngology-Head and Neck Surgery, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Sunkon Yu
- Department of Biomedical Engineering, Yonsei University College of Health Science, Wonju, South Korea
| | - Byungjo Jung
- Department of Biomedical Engineering, Yonsei University College of Health Science, Wonju, South Korea
| | - Jin Sil Choi
- Department of Otorhinolaryngology-Head and Neck Surgery, Yonsei University Wonju College of Medicine, Wonju, South Korea
| | - Young Joon Seo
- Department of Otorhinolaryngology-Head and Neck Surgery, Yonsei University Wonju College of Medicine, Wonju, South Korea
- * E-mail:
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Cochlear implantation in the mouse via the round window: effects of array insertion. Hear Res 2014; 312:81-90. [PMID: 24657211 DOI: 10.1016/j.heares.2014.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 02/05/2014] [Accepted: 03/05/2014] [Indexed: 02/07/2023]
Abstract
Animal models are the only means of assessing the effects of cochlear implantation (CI) at a cellular and molecular level. The range of naturally occurring and genetically-modified mouse strains which mimic human deafness provide excellent opportunities for auditory research. To date, there are very few studies of CI in mice. The main aims of this study were to develop a reproducible and viable technique to enable long term CI in the mouse and to assess the response of the mouse cochlea to implantation as a means of evaluating the success of the procedure. Electrode array implantation via the round window was performed in C57Bl/6 mice aged 3 and 6 months. The contralateral cochlea acted as a control. Auditory brainstem responses (ABR) were recorded prior to and following CI. Analysis showed greater threshold shifts in the implanted ear compared to the control ear post-implantation, but substantial preservation of hearing. There were no cases in which implantation caused a profound hearing loss across all frequencies. Cone beam computerised tomography and light microscopy confirmed correct placement of the electrode array within the scala tympani. Cochleae were prepared for histological examination. Initial analysis revealed encapsulation of the implant in tissue with morphological characteristics suggestive of fibrosis. Our results show that mouse CI via the round window offers a model for exploring tissue responses to implantation.
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Reif R, Zhi Z, Dziennis S, Nuttall AL, Wang RK. Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry. Quant Imaging Med Surg 2013; 3:235-42. [PMID: 24273740 DOI: 10.3978/j.issn.2223-4292.2013.10.02] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 10/08/2013] [Indexed: 12/11/2022]
Abstract
In this work we determined the contributions of loud sound exposure (LSE) on cochlear blood flow (CoBF) in an in vivo anesthetized mouse model. A broadband noise system (20 kHz bandwidth) with an intensity of 119 dB SPL, was used for a period of one hour to produce a loud sound stimulus. Two techniques were used to study the changes in blood flow, a Doppler optical microangiography (DOMAG) system; which can measure the blood flow within individual cochlear vessels, and a laser Doppler flowmetry (LDF) system; which averages the blood flow within a volume (a hemisphere of ~1.5 mm radius) of tissue. Both systems determined that the blood flow within the cochlea is reduced due to the LSE stimulation.
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Affiliation(s)
- Roberto Reif
- University of Washington, Department of Bioengineering, Seattle, WA 98195, USA
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Soken H, Robinson BK, Goodman SS, Abbas PJ, Hansen MR, Kopelovich JC. Mouse cochleostomy: a minimally invasive dorsal approach for modeling cochlear implantation. Laryngoscope 2013; 123:E109-15. [PMID: 23674233 DOI: 10.1002/lary.24174] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 02/25/2013] [Accepted: 04/02/2013] [Indexed: 11/05/2022]
Abstract
OBJECTIVES/HYPOTHESIS The murine model has been used extensively to model and study human deafness. Technical difficulty in the surgical approach due to the small size of the tympanic bulla and a robust stapedial artery has limited its application for studies of cochlear implantation and electrical stimulation. We describe a minimally traumatic, stapedial artery-sparing approach to the round window that may be used to access the mouse cochlea for acute or chronic studies of implantation and stimulation. STUDY DESIGN Animal model. METHODS Fifteen C57BL6J mice were used to validate this approach. Auditory brainstem response threshold and distortion product otoacoustic emissions were obtained preoperatively and 2 weeks postoperatively to determine hearing preservation results. RESULTS The approach provided excellent exposure for round-window implantation. Substantial hearing was preserved in all animals with a mean postimplantation auditory brainstem response threshold increase of 27.8 dB. Otoacoustic emissions were lost in subjects with the largest threshold shifts. CONCLUSIONS Residual hearing after cochlear implantation is a determinant of success both with standard cochlear implant electrodes and with electrodes designed to optimize hearing preservation. Here, we have preserved usable hearing after implantation of C57BL6J mice, an endogenous model of human presbycusia. The murine model may become a powerful tool to assay the effects of cochlear intervention in different genetic backgrounds.
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Affiliation(s)
- Hakan Soken
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, Iowa, U.S.A
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Fujita T, Yamashita D, Katsunuma S, Hasegawa S, Tanimoto H, Nibu KI. Increased inner ear susceptibility to noise injury in mice with streptozotocin-induced diabetes. Diabetes 2012; 61:2980-6. [PMID: 22851574 PMCID: PMC3478526 DOI: 10.2337/db11-1845] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We aimed to investigate the pathophysiology of diabetes-associated hearing impairment in type 1 diabetes using mice with streptozotocin-induced diabetes (C57BL/6J; male). Hearing function was evaluated 1, 3, and 5 months after induction of diabetes (five diabetic and five control animals per time point) using auditory-evoked brain stem responses (ABRs). Mice (four diabetic and four control) were exposed to loud noise (105 dB) 5 months after induction of diabetes. ABRs were measured before and after noise exposure. Cochlear blood flows were measured by laser-Doppler flowmeter. Spiral ganglion cells (SGCs) were counted. Vessel endothelial cells were observed by CD31 immunostaining. Chronologic changes in the ABR threshold shift were not significantly different between the diabetic and control groups. However, vessel walls in the modiolus of the cochleae were significantly thicker in the diabetic group than the control group. Additionally, recovery from noise-induced injury was significantly impaired in diabetic mice. Reduced cochlea blood flows and SGC loss were observed in diabetic mice cochleae after noise exposure. Our data suggest that diabetic cochleae are more susceptible than controls to loud noise exposure, and decreased cochlear blood flow due to sclerosis of the vessels and consequent loss of SGCs are possible mechanisms of hearing impairment in diabetic patients.
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MESH Headings
- Animals
- Cell Count
- Cochlea/blood supply
- Cochlea/pathology
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Diabetes Mellitus, Type 1/physiopathology
- Disease Susceptibility
- Ear, Inner/blood supply
- Ear, Inner/pathology
- Ear, Inner/physiopathology
- Endothelial Cells/metabolism
- Endothelial Cells/pathology
- Evoked Potentials, Auditory, Brain Stem
- Hearing Loss, Noise-Induced/complications
- Hearing Loss, Noise-Induced/rehabilitation
- Laser-Doppler Flowmetry
- Male
- Mice
- Mice, Inbred C57BL
- Microcirculation
- Microvessels/pathology
- Microvessels/physiopathology
- Platelet Endothelial Cell Adhesion Molecule-1/metabolism
- Random Allocation
- Sclerosis
- Spiral Ganglion/pathology
- Streptozocin
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Affiliation(s)
- Takeshi Fujita
- Department of Otolaryngology–Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
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Dziennis S, Reif R, Zhi Z, Nuttall AL, Wang RK. Effects of hypoxia on cochlear blood flow in mice evaluated using Doppler optical microangiography. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:106003. [PMID: 23224002 PMCID: PMC3461130 DOI: 10.1117/1.jbo.17.10.106003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Reduced cochlear blood flow (CoBF) is a main contributor to hearing loss. Studying CoBF has remained a challenge due to the lack of available tools. Doppler optical microangiography (DOMAG), a method to quantify single-vessel absolute blood flow, and laser Doppler flowmetry (LDF), a method for measuring the relative blood flow within a large volume of tissue, were used for determining the changes in CoBF due to systemic hypoxia in mice. DOMAG determined the change in blood flow in the apical turn (AT) with single-vessel resolution, while LDF averaged the change in the blood flow within a large volume of the cochlea (hemisphere with ∼1 to 1.5 mm radius). Hypoxia was induced by decreasing the concentration of oxygen-inspired gas, so that the oxygen saturation was reduced from >95% to ∼80%. DOMAG determined that during hypoxia the blood flow in two areas of the AT near and far from the helicotrema were increased and decreased, respectively. The LDF detected a decrease in blood flow within a larger volume of the cochlea (several turns averaged together). Therefore, the use of DOMAG as a tool for studying cochlear blood flow due to its ability to determine absolute flow values with single-vessel resolution was proposed.
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Affiliation(s)
- Suzan Dziennis
- University of Washington, Department of Bioengineering, 3720 15th Avenue N.E., Seattle, Washington 98195
| | - Roberto Reif
- University of Washington, Department of Bioengineering, 3720 15th Avenue N.E., Seattle, Washington 98195
| | - Zhongwei Zhi
- University of Washington, Department of Bioengineering, 3720 15th Avenue N.E., Seattle, Washington 98195
| | - Alfred L. Nuttall
- Oregon Health and Science University, Oregon Hearing Research Center, School of Medicine, Portland, Oregon 97239
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 15th Avenue N.E., Seattle, Washington 98195
- Address all correspondence to: Ruikang K. Wang, University of Washington, Department of Bioengineering, 3720 15th Avenue N.E., Seattle, Washington 98195. Tel: 206 616 5025; Fax: 206 685 3300; E-mail:
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9
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Erdogan S, Kilinc M. Gross anatomy and arterial vascularization of the tympanic cavity and osseous labyrinth in mid-gestational bovine fetuses. Anat Rec (Hoboken) 2010; 293:2083-93. [DOI: 10.1002/ar.21269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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The ventrolateral surgical approach to labyrinthectomy in rats: anatomical description and clinical consequences. Surg Radiol Anat 2010; 32:835-42. [DOI: 10.1007/s00276-010-0690-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Accepted: 06/21/2010] [Indexed: 11/26/2022]
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Lataye R, Maguin K, Campo P. Increase in cochlear microphonic potential after toluene administration. Hear Res 2007; 230:34-42. [PMID: 17555896 DOI: 10.1016/j.heares.2007.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 03/15/2007] [Accepted: 04/06/2007] [Indexed: 10/23/2022]
Abstract
Human and animal studies have shown that toluene can cause hearing loss. In the rat, the outer hair cells are first disrupted by the ototoxicant. Because of their particular sensitivity to toluene, the cochlear microphonic potential (CMP) was used for monitoring the cochlea activity of anesthetized rats exposed to both noise (band noise centered at 4 kHz) and toluene. In the present experiment, the conditions were specifically designed to study the toluene effects on CMP and not those of its metabolites. To this end, 100-microL injections of a vehicle containing different concentrations of solvent were made into the carotid artery connected to the tested cochlea. Interestingly, an injection of 116.2-mM toluene dramatically increased in the CMP amplitude (approximately 4 dB) in response to an 85-dB SPL noise. Moreover, the rise in CMP magnitude was intensity dependent at this concentration suggesting that toluene could inhibit the auditory efferent system involved in the inner-ear or/and middle-ear acoustic reflexes. Because acetylcholine is the neurotransmitter mediated by the auditory efferent bundles, injections of antagonists of cholinergic receptors (AchRs) such as atropine, 4-diphenylacetoxy-N-methylpiperidine-methiodide (mAchR antagonist) and dihydro-beta-erythroidine (nAchR antagonist) were also tested in this investigation. They all provoked rises in CMP having amplitudes as large as those obtained with toluene. The results showed for the first time in an in vivo study that toluene mimics the effects of AchR antagonists. It is likely that toluene might modify the response of protective acoustic reflexes.
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Affiliation(s)
- Robert Lataye
- Laboratoire de Neurotoxicité, Institut National de Recherche et de Sécurité, Avenue de Bourgogne, BP 27 Vandoeuvre, 54501 Cedex, France
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Lu W, Xu J, Shepherd RK. Cochlear implantation in rats: a new surgical approach. Hear Res 2006; 205:115-22. [PMID: 15953521 PMCID: PMC1831821 DOI: 10.1016/j.heares.2005.03.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Accepted: 03/10/2005] [Indexed: 01/29/2023]
Abstract
The laboratory rat has been used extensively in auditory research but has had limited use in cochlear implant related research due mainly to the surgically restricted access to the scala tympani. We have developed a new surgical method for cochlear implantation in rats. The key to this protocol was cauterizing the stapedial artery (SA) and making a small cochleostomy near the round window in order to enlarge the surgical access to the scala tympani. Five normal hearing Hooded Wistar rats were used to investigate the effect of cauterizing the SA on hearing and auditory nerve survival. Results showed that cauterizing the SA was surgically feasible, afforded excellent exposure of the round window niche for cochleostomy, and did not adversely affect acoustic thresholds measured electrophysiologically. Moreover, there was no difference in spiral ganglion cell densities for any cochlear turn when compared with the contralateral control ears. Three deafened rats were subsequently implanted with a scala tympani electrode array using this new surgical approach. Electrically evoked auditory brainstem responses using bipolar stimulation, and subsequent cochlear histopathology demonstrated that cochlear implantation using a custom-made rat electrode array was safe and effective. The surgical approach presented in this paper presents a safe and effective procedure for acute or chronic cochlear implantation in the rat model.
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Affiliation(s)
- Wei Lu
- Department of Otolaryngology, Royal Victorian Eye and Ear Hospital, The University of Melbourne, 32 Gisborne Street, East Melbourne, Vic. 3002, Australia
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Tominaga M, Yamamoto H, Sone M, Teranishi MA, Nakashima T. Response of cochlear blood flow to prostaglandin E1 applied topically to the round window. Acta Otolaryngol 2006; 126:232-6. [PMID: 16618646 DOI: 10.1080/00016480500316803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONCLUSIONS The increase in cochlear blood flow (CBF) after administration of prostaglandin E1 (PGE1) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA). OBJECTIVES To evaluate the response of CBF to PGE1 applied topically to the round window, and to investigate the origin of blood flow changes after this topical application. MATERIAL AND METHODS The response of CBF to topically applied PGE1 was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats. In rats, the CBF response to PGE1 administration was investigated after occlusion of the AICA or stapedial artery. RESULTS CBF increased following PGE1 administration in both guinea pigs and rats. In rats, CBF increased from 100% to 132%+/-10% (mean+/-SD) after the topical application of 0.5 microl of a 0.014% PGE1 solution. CBF decreased after occlusion of the AICA or stapedial artery but did not increase after PGE1 administration during occlusion of the AICA. The CBF response to PGE1 administration was similar before and after occlusion of the stapedial artery.
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Affiliation(s)
- Mitsuo Tominaga
- Department of Otorhinolaryngology, Nagoya University School of Medicine, Nagoya, Japan
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Chen Z, Mikulec AA, McKenna MJ, Sewell WF, Kujawa SG. A method for intracochlear drug delivery in the mouse. J Neurosci Methods 2005; 150:67-73. [PMID: 16043228 DOI: 10.1016/j.jneumeth.2005.05.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Revised: 05/03/2005] [Accepted: 05/31/2005] [Indexed: 11/28/2022]
Abstract
The confluence of two rapidly emerging research arenas - development of mouse models of human deafness and inner ear drug therapy for treatment and prevention of hearing loss - provides an opportunity for unprecedented approaches to study and treat deafness. Toward such goals, we have developed a method for intracochlear drug delivery in the mouse. The bulla was exposed using a ventral approach and the stapedial artery cauterized. An opening made into the inferior-medial aspect of the bulla, where the basal cochlear wall fuses with tympanic bulla, provided direct access to the scala tympani without separately opening the bulla or elevating auditory response thresholds. Cochlear responses, assayed by frequency-specific effects on ABRs and DPOAEs, were stable with infusion (1 microl/h) of an artificial perilymph solution (80 min). The glutamate receptor antagonist, CNQX (100 microM; 175 min), reduced ABR responses without affecting DPOAEs. Salicylate (5mM; 165 min) altered both. Both drugs had greatest effects at high frequencies, but distributed throughout the cochlea and were reversible. The safe delivery of drugs into the cochlea by this approach has immediate application in the study and treatment of various forms of human hearing loss that can be modeled in the mouse.
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Affiliation(s)
- Zhiqiang Chen
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, USA.
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15
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Eshraghi AA, Polak M, He J, Telischi FF, Balkany TJ, Van De Water TR. Pattern Of Hearing Loss In A Rat Model Of Cochlear Implantation Trauma. Otol Neurotol 2005; 26:442-7; discussion 447. [PMID: 15891647 DOI: 10.1097/01.mao.0000169791.53201.e1] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS Trauma caused by cochlear implant electrode insertion is attributable to the combination of direct physical trauma and the delayed cell death of oxidative stress-injured auditory sensory cells. BACKGROUND Histologic evaluation of cochlear implant electrode trauma has demonstrated that the extent of sensory cell losses is proportional to the degree of injury. However, the impact of delayed oxidative stress within injured cochlear tissues and the progressive loss of injured hair cells by way of apoptosis are at present unknown. METHODS Laboratory rats were evaluated for hearing acuity before and after electrode insertion, before and after round window membrane incision only. Hearing was measured before trauma or incision and over the next 7 days. Objective measurements of hearing function were distortion products of otoacoustic emissions (DPOAEs) in the frequency range of 2 to 32 kHz and tone-burst (i.e., 4-32 kHz) evoked auditory brain stem responses (ABRs). RESULTS For the experimental cochleae, there were progressive increases in ABR thresholds and decreases in ABR amplitudes. The amplitude of the DPOAEs in the experimental cochleae also showed progressive decreases. For the contralateral control and round window membrane surgical control ears, there were no significant changes in either DPOAE or ABR thresholds. CONCLUSION These results document a progressive loss of hearing acuity postimplantation and strongly suggest that electrode insertion trauma generated oxidative stress within injured cochlear tissues.
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Affiliation(s)
- Adrien A Eshraghi
- Department of Otolaryngology, University of Miami Leonard M. Miller School of Medicine, Miami, Florida, USA
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