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Krawczyk A, Mozel S, Rycerz K, Jaworska-Adamu J, Arciszewski MB. Immunoreactivity of glutamine synthetase in satellite glia around various subpopulations of lumbar dorsal root ganglia neurons in adult rats treated with monosodium glutamate. J Chem Neuroanat 2023; 134:102347. [PMID: 37838216 DOI: 10.1016/j.jchemneu.2023.102347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/30/2023] [Accepted: 10/09/2023] [Indexed: 10/16/2023]
Abstract
Satellite glial cells (SGCs), involved inter alia in glutamate (Glu) metabolism, form a glial sheath around sensory neurons of dorsal root ganglia (DRGs). SGCs show a presence of glutamine synthetase (GS) which transform uptaken Glu into glutamine (Gln). In DRGs, this aminoacid is used mainly by small neurons which are able to synthetize substance P (SP) that play a crucial role in nociception. The aim of the study was to define the influence of monosodium glutamate (MSG) on GS immunoreactivity in satellite glia around various subpopulations of neurons including SP immunopositive cells in DRGs of adult rats. The studies were carried out on lumbar DRGs slides in rats which received subcutaneous injection of saline solution (control group) or 4 g/kg b. w. of MSG (MSG group). Immunofluorescence reactions were conducted with use of anti-GS and anti-SP antibodies. Administration of MSG to adult rats increased the GS immunoexpression in SGCs. In rats receiving MSG, a number of small neurons with GS-immunopositive glial sheath was not altered when compared to control individuals, whereas there was a statistically significant increase of GS immunoexpression in SGCs around large and medium neurons. Moreover, in these animals, a statistically significant increase in the number of small SP-positive neurons with GS-positive glial sheath was observed. SP is responsible for transmission of pain, thus the obtained results may be useful for further research concerning the roles of glia in nociceptive pathway regulation.
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Affiliation(s)
- Aleksandra Krawczyk
- Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences, Lublin, Poland
| | - Sylwia Mozel
- Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences, Lublin, Poland.
| | - Karol Rycerz
- Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences, Lublin, Poland
| | - Jadwiga Jaworska-Adamu
- Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences, Lublin, Poland
| | - Marcin Bartłomiej Arciszewski
- Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences, Lublin, Poland
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2
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van Dieken A, Staecker H, Schmitt H, Harre J, Pich A, Roßberg W, Lenarz T, Durisin M, Warnecke A. Bioinformatic Analysis of the Perilymph Proteome to Generate a Human Protein Atlas. Front Cell Dev Biol 2022; 10:847157. [PMID: 35573665 PMCID: PMC9096870 DOI: 10.3389/fcell.2022.847157] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 04/04/2022] [Indexed: 11/16/2022] Open
Abstract
The high complexity of the cellular architecture of the human inner ear and the inaccessibility for tissue biopsy hampers cellular and molecular analysis of inner ear disease. Sampling and analysis of perilymph may present an opportunity for improved diagnostics and understanding of human inner ear pathology. Analysis of the perilymph proteome from patients undergoing cochlear implantation was carried out revealing a multitude of proteins and patterns of protein composition that may enable characterisation of patients into subgroups. Based on existing data and databases, single proteins that are not present in the blood circulation were related to cells within the cochlea to allow prediction of which cells contribute to the individual perilymph proteome of the patients. Based on the results, we propose a human atlas of the cochlea. Finally, druggable targets within the perilymph proteome were identified. Understanding and modulating the human perilymph proteome will enable novel avenues to improve diagnosis and treatment of inner ear diseases.
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Affiliation(s)
- Alina van Dieken
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Hinrich Staecker
- Department of Otolaryngology, Head and Neck, Surgery, University of Kansas School of Medicine, Kansas City, KS, United States
| | - Heike Schmitt
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Jennifer Harre
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Pich
- Core Facility Proteomics, Hannover Medical School, Hannover, Germany
| | - Willi Roßberg
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Martin Durisin
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
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Guven SG, Ersoy O, Topuz RD, Bulut E, Kizilay G, Uzun C. Does Oral Monosodium Glutamate Have a Cochleotoxic Effect? An Experimental Study. Audiol Neurootol 2021; 27:109-121. [PMID: 34535584 DOI: 10.1159/000518616] [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: 05/19/2021] [Accepted: 07/19/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION The effect of orally consumed monosodium glutamate (MSG), which is a common additive in the food industry, on the cochlea has not been investigated. The present study aimed to investigate the possible cochleotoxic effects of oral MSG in guinea pigs using electrophysiological, biochemical, and histopathological methods. METHODS Thirty guinea pigs were equally divided into control and intervention groups (MSG 100 mg/kg/day; MSG 300 mg/kg/day). At 1 month, 5 guinea pigs from each group were sacrificed; the rest were observed for another month. Electrophysiological measurements (distortion product otoacoustic emission [DPOAE] and auditory brainstem response [ABR]), glutamate levels in the perilymph and blood samples, and histopathological examinations were evaluated at 1 and 2 months. RESULTS Change in signal-to-noise ratio at 2 months was significantly different in the MSG 300 group at 0.75 kHz and 2 kHz (p = 0.013 and p = 0.044, respectively). There was no statistically significant difference in ABR wave latencies of the guinea pigs given MSG compared to the control group after 1 and 2 months; an increase was noted in ABR thresholds, although the difference was not statistically significant. In the MSG groups, moderate-to-severe degeneration and cell loss in outer hair cells, support cells, and spiral ganglia, lateral surface junction irregularities, adhesions in stereocilia, and partial loss of outer hair cell stereocilia were noted. CONCLUSION MSG, administered in guinea pigs at a commonly utilized quantity and route of administration in humans, may be cochleotoxic.
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Affiliation(s)
- Selis Gulseven Guven
- Department of Otorhinolaryngology, Head and Neck Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Onur Ersoy
- Department of Pathology Laboratory Techniques, Vocational School of Health Services, Trakya University, Edirne, Turkey
| | - Ruhan Deniz Topuz
- Department of Pharmacology, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Erdoğan Bulut
- Department of Audiology, Trakya University Faculty of Health Sciences, Edirne, Turkey
| | - Gulnur Kizilay
- Department of Histology and Embryology, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Cem Uzun
- Department of Otorhinolaryngology, Head and Neck Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
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4
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Kohrman D, Borges BC, Cassinotti L, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 PMCID: PMC9004231 DOI: 10.1002/dneu.22813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/25/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
The auditory system detects and encodes sound information with high precision to provide a high-fidelity representation of the environment and communication. In mammals, detection occurs in the peripheral sensory organ (the cochlea) containing specialized mechanosensory cells (hair cells) that initiate the conversion of sound-generated vibrations into action potentials in the auditory nerve. Neural activity in the auditory nerve encodes information regarding the intensity and frequency of sound stimuli, which is transmitted to the auditory cortex through the ascending neural pathways. Glial cells are critical for precise control of neural conduction and synaptic transmission throughout the pathway, allowing for the precise detection of the timing, frequency, and intensity of sound signals, including the sub-millisecond temporal fidelity is necessary for tasks such as sound localization, and in humans, for processing complex sounds including speech and music. In this review, we focus on glia and glia-like cells that interact with hair cells and neurons in the ascending auditory pathway and contribute to the development, maintenance, and modulation of neural circuits and transmission in the auditory system. We also discuss the molecular mechanisms of these interactions, their impact on hearing and on auditory dysfunction associated with pathologies of each cell type.
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Affiliation(s)
- David Kohrman
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Beatriz C. Borges
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Luis Cassinotti
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Lingchao Ji
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
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5
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Wu M, Xia M, Li W, Li H. Single-Cell Sequencing Applications in the Inner Ear. Front Cell Dev Biol 2021; 9:637779. [PMID: 33644075 PMCID: PMC7907461 DOI: 10.3389/fcell.2021.637779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/21/2021] [Indexed: 01/29/2023] Open
Abstract
Genomics studies face specific challenges in the inner ear due to the multiple types and limited amounts of inner ear cells that are arranged in a very delicate structure. However, advances in single-cell sequencing (SCS) technology have made it possible to analyze gene expression variations across different cell types as well as within specific cell groups that were previously considered to be homogeneous. In this review, we summarize recent advances in inner ear research brought about by the use of SCS that have delineated tissue heterogeneity, identified unknown cell subtypes, discovered novel cell markers, and revealed dynamic signaling pathways during development. SCS opens up new avenues for inner ear research, and the potential of the technology is only beginning to be explored.
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Affiliation(s)
- Mingxuan Wu
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Mingyu Xia
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Wenyan Li
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Huawei Li
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,The Institutes of Brain Science and The Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
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6
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Sahley TL, Anderson DJ, Hammonds MD, Chandu K, Musiek FE. Evidence for a dynorphin-mediated inner ear immune/inflammatory response and glutamate-induced neural excitotoxicity: an updated analysis. J Neurophysiol 2019; 122:1421-1460. [DOI: 10.1152/jn.00595.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acoustic overstimulation (AOS) is defined as the stressful overexposure to high-intensity sounds. AOS is a precipitating factor that leads to a glutamate (GLU)-induced Type I auditory neural excitotoxicity and an activation of an immune/inflammatory/oxidative stress response within the inner ear, often resulting in cochlear hearing loss. The dendrites of the Type I auditory neural neurons that innervate the inner hair cells (IHCs), and respond to the IHC release of the excitatory neurotransmitter GLU, are themselves directly innervated by the dynorphin (DYN)-bearing axon terminals of the descending brain stem lateral olivocochlear (LOC) system. DYNs are known to increase GLU availability, potentiate GLU excitotoxicity, and induce superoxide production. DYNs also increase the production of proinflammatory cytokines by modulating immune/inflammatory signal transduction pathways. Evidence is provided supporting the possibility that the GLU-mediated Type I auditory neural dendritic swelling, inflammation, excitotoxicity, and cochlear hearing loss that follow AOS may be part of a brain stem-activated, DYN-mediated cascade of inflammatory events subsequent to a LOC release of DYNs into the cochlea. In support of a DYN-mediated cascade of events are established investigations linking DYNs to the immune/inflammatory/excitotoxic response in other neural systems.
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Affiliation(s)
- Tony L. Sahley
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
- School of Health Sciences, Cleveland State University, Cleveland, Ohio
| | - David J. Anderson
- Department of Chemistry, Cleveland State University, Cleveland, Ohio
| | | | - Karthik Chandu
- Department of Chemistry, Cleveland State University, Cleveland, Ohio
| | - Frank E. Musiek
- Department of Speech, Language, and Hearing Sciences, University of Arizona, Tucson, Arizona
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Carricondo F, Romero-Gómez B. The Cochlear Spiral Ganglion Neurons: The Auditory Portion of the VIII Nerve. Anat Rec (Hoboken) 2018; 302:463-471. [DOI: 10.1002/ar.23815] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/08/2017] [Accepted: 10/08/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Francisco Carricondo
- Laboratory of Neurobiology of Hearing, Dept. of Immunology, Ophthalmology and Otorhinolaryngology, Faculty of Medicine; Complutense University of Madrid (Spain)
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos" (IdISSC); Madrid Spain
| | - Bárbara Romero-Gómez
- Laboratory of Neurobiology of Hearing, Dept. of Immunology, Ophthalmology and Otorhinolaryngology, Faculty of Medicine; Complutense University of Madrid (Spain)
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos" (IdISSC); Madrid Spain
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8
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Yu P, Jiao J, Chen G, Zhou W, Zhang H, Wu H, Li Y, Gu G, Zheng Y, Yu Y, Yu S. Effect of GRM7 polymorphisms on the development of noise-induced hearing loss in Chinese Han workers: a nested case-control study. BMC MEDICAL GENETICS 2018; 19:4. [PMID: 29301492 PMCID: PMC5755024 DOI: 10.1186/s12881-017-0515-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/19/2017] [Indexed: 01/09/2023]
Abstract
Background Noise-induced hearing loss (NIHL) is a complex, irreversible disease caused by the interaction of genetic and environmental factors. In recent years, a great many studies have been done to explore the NIHL susceptibility genes among humans. So far, high powerful detections have been founded that genes of potassium ion channel genes (KCNQ4 and KCNE1), catalase (CAT), protocadherin 15 (PCDH15), myosin 14 (MYH14) and heart shock protein (HSP70) which have been identified in more than one population may be associated with the susceptibility to NIHL. As for metabolic glutamate receptor7 gene (GRM7), a lot of researches mainly focus on age-related hearing loss (ARHL) and the results have shown that the polymorphisms of GRM7 are linked to the development of ARHL. However, little is known about the association of GRM7 and the susceptibility to NIHL. Therefore, the aim of this study was to explore the effect of GRM7 polymorphisms on the susceptibility to NIHL. Methods A nested case-control study based on the cohort in a Chinese steel factory was implemented in 292 cases and 584 controls matched with the same sex, the age difference ≤ 5 years old, the same type of work, duration of occupational noise exposure ≤2 years. Five single nucleotide polymorphisms (SNPs) of GRM7 were gained through selecting and genotyping SNPs. Conditional logistic regression analysis was used to assess the main effect of GRM7 polymorphisms on the susceptibility to NIHL and the gene-by-environment interaction. Furthermore, the gene-by-gene interactions were analyzed by generalized multiple dimensionality reduction (GMDR). Results This research discovered for the first time that the mutant allele C in rs1485175 of the GMR7 may decrease individuals’ susceptibility to NIHL. The interaction between rs1485175 and cumulative noise exposure (CNE) at high level was found after the stratification according to CNE (p/pbon = 0.014/0.007, OR = 0.550, 95% CI: 0.340–0.891). Permutation test of GMDR suggested that rs1920109, rs1485175 and rs9826579 in GRM7 might interact with each other in the process of developing NIHL (p = 0.037). Conclusions The results suggest that the mutant allele C of rs1485175 in GRM7 may reduce the susceptibility to NIHL in Chinese Han population. Electronic supplementary material The online version of this article (10.1186/s12881-017-0515-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Peipei Yu
- Department of Occupational and Environmental Health Hygiene, College of Public Health, Zhengzhou University, Zhengzhou, Henan, People's Republic of China.,Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Jie Jiao
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Guoshun Chen
- Wugang Institute for Occupational Health, Wugang, Henan, People's Republic of China
| | - Wenhui Zhou
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Huanling Zhang
- Wugang Institute for Occupational Health, Wugang, Henan, People's Republic of China
| | - Hui Wu
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Yanhong Li
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Guizhen Gu
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China
| | - Yuxin Zheng
- College of Public Health, Qingdao University, Qingdao, Shandong, People's Republic of China
| | - Yue Yu
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Shanfa Yu
- Henan Provincial Institute for Occupational Health, No.3, Kangfu Mid. St, Zhengzhou, 450052, People's Republic of China.
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9
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Wan G, Corfas G. Transient auditory nerve demyelination as a new mechanism for hidden hearing loss. Nat Commun 2017; 8:14487. [PMID: 28211470 PMCID: PMC5321746 DOI: 10.1038/ncomms14487] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022] Open
Abstract
Hidden hearing loss (HHL) is a recently described auditory neuropathy believed to contribute to speech discrimination and intelligibility deficits in people with normal audiological tests. Animals and humans with HHL have normal auditory thresholds but defective cochlear neurotransmission, that is, reduced suprathreshold amplitude of the sound-evoked auditory nerve compound action potential. Currently, the only cellular mechanism known for HHL is loss of inner hair cell synapses (synaptopathy). Here we report that transient loss of cochlear Schwann cells results in permanent auditory deficits characteristic of HHL. This auditory neuropathy is not associated with synaptic loss, but rather with disruption of the first heminodes at the auditory nerve peripheral terminal. Thus, this study identifies a new mechanism for HHL, highlights the long-term consequences of transient Schwann cell loss on hearing and might provide insights into the causes of the auditory deficits reported in patients that recover from acute demyelinating diseases such as Guillain–Barré syndrome. Hidden hearing loss (HHL) is an auditory neuropathy that impairs one's ability to hear, particularly in a noisy environment. Here the authors show that in mice, transient loss of cochlear Schwann cells results in permanent disruption of the cochlear heminodal structure, leading to auditory deficits characteristic of HHL.
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Affiliation(s)
- Guoqiang Wan
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA.,MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu Province, China
| | - Gabriel Corfas
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA
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10
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Johnson Chacko L, Pechriggl EJ, Fritsch H, Rask-Andersen H, Blumer MJF, Schrott-Fischer A, Glueckert R. Neurosensory Differentiation and Innervation Patterning in the Human Fetal Vestibular End Organs between the Gestational Weeks 8-12. Front Neuroanat 2016; 10:111. [PMID: 27895556 PMCID: PMC5108762 DOI: 10.3389/fnana.2016.00111] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/28/2016] [Indexed: 11/13/2022] Open
Abstract
Balance orientation depends on the precise operation of the vestibular end organs and the vestibular ganglion neurons. Previous research on the assemblage of the neuronal network in the developing fetal vestibular organ has been limited to data from animal models. Insights into the molecular expression profiles and signaling moieties involved in embryological development of the human fetal inner ear have been limited. We present an investigation of the cells of the vestibular end organs with specific focus on the hair cell differentiation and innervation pattern using an uninterrupted series of unique specimens from gestational weeks 8-12. Nerve fibers positive for peripherin innervate the entire fetal crista and utricle. While in rodents only the peripheral regions of the cristae and the extra-striolar region of the statolithic organs are stained. At week 9, transcription factors PAX2 and PAX8 were observed in the hair cells whereas PAX6 was observed for the first time among the supporting cells of the cristae and the satellite glial cells of the vestibular ganglia. Glutamine synthetase, a regulator of the neurotransmitter glutamate, is strongly expressed among satellite glia cells, transitional zones of the utricle and supporting cells in the sensory epithelium. At gestational week 11, electron microscopic examination reveals bouton contacts at hair cells and first signs of the formation of a protocalyx at type I hair cells. Our study provides first-hand insight into the fetal development of the vestibular end organs as well as their pattern of innervation by means of immunohistochemical and EM techniques, with the aim of contributing toward our understanding of balance development.
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Affiliation(s)
- Lejo Johnson Chacko
- Department of Otolaryngology, Medical University of Innsbruck Innsbruck, Austria
| | - Elisabeth J Pechriggl
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional Anatomy, Medical University of Innsbruck Innsbruck, Austria
| | - Helga Fritsch
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional Anatomy, Medical University of Innsbruck Innsbruck, Austria
| | | | - Michael J F Blumer
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional Anatomy, Medical University of Innsbruck Innsbruck, Austria
| | | | - Rudolf Glueckert
- Department of Otolaryngology, Medical University of InnsbruckInnsbruck, Austria; University Clinics Innsbruck, Tirol KlinikenInnsbruck, Austria
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11
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Mullin EJ, Wegst-Uhrich SR, Ding D, Manohar S, Krishnan Muthaiah VP, Salvi R, Aga DS, Roth JA. Effect of manganese treatment on the accumulation on biologically relevant metals in rat cochlea and brain by inductively coupled plasma mass spectrometry. Biometals 2015; 28:1009-16. [PMID: 26433897 DOI: 10.1007/s10534-015-9885-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 09/25/2015] [Indexed: 12/26/2022]
Abstract
Manganese (Mn), iron (Fe), zinc (Zn), and copper (Cu) are essential transitions metals that are required in trace amounts, however chronic exposure to high concentrations can cause severe and irreversible neurotoxicity. Since prolonged exposure to Mn leads to manganism, a disorder exhibiting a diverse array of neurological impairments progressing to a debilitating and irreversible extrapyramidal condition symptomatically similar to Parkinson's disease, we measured the concentration of Mn as well as Fe, Zn and Cu in three region of the brain (globus pallidus, striatum and inferior colliculus) and three regions in the cochlea (stria vascularis, basilar membrane and modiolus) under normal conditions or after 30 or 60 days of oral administration of Mn (10 mg/ml ad libitum). Under normal conditions, Mn, Zn and Fe were typically higher in the cochlea than in the three brain regions whereas Cu was equal to or lower. Oral treatment with Mn for 30 or 60 days resulted in 20-75 % increases in Mn concentrations in both cochlea and brain samples, but had little effect on Cu and Fe levels. In contrast, Zn levels decreased (20-80 %) with Mn exposure. Our results show for the first time how prolonged oral Mn-ingestion affects the concentration of Mn, Cu, Zn and Fe, in the three regions of the cochlea, the inferior colliculus in auditory midbrain and the striatum and globus pallidus, two regions implicated in Parkinson's disorder. The Mn-induced changes in the concentration of Mn, Cu, Zn and Fe may provide new insights relevant to the neurotoxicity of Mn and the transport and accumulation of these metals in cochlea and brain.
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Affiliation(s)
- Elizabeth J Mullin
- Department of Chemistry, University at Buffalo, Buffalo, NY, 14260, USA.
| | | | - Dalian Ding
- Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY, 14214, USA. .,Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA.
| | | | - Richard Salvi
- Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY, 14214, USA.
| | - Diana S Aga
- Department of Chemistry, University at Buffalo, Buffalo, NY, 14260, USA.
| | - Jerome A Roth
- Department of Pharmacology and Toxicology, University at Buffalo, 11 Cary Hall, Buffalo, NY, 14214, USA.
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12
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Pechriggl EJ, Bitsche M, Glueckert R, Rask‐Andersen H, Blumer MJF, Schrott‐Fischer A, Fritsch H. Development of the innervation of the human inner ear. Dev Neurobiol 2014; 75:683-702. [DOI: 10.1002/dneu.22242] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 10/28/2014] [Accepted: 10/28/2014] [Indexed: 01/04/2023]
Affiliation(s)
- Elisabeth J. Pechriggl
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional AnatomyMedical University of InnsbruckMüllerstrasse 596020Innsbruck Austria
| | - Mario Bitsche
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional AnatomyMedical University of InnsbruckMüllerstrasse 596020Innsbruck Austria
| | - Rudolf Glueckert
- Department of OtolaryngologyMedical University of InnsbruckAnichstrasse 356020Innsbruck Austria
- University Clinics InnsbruckTiroler LandeskrankenanstaltenInnsbruck Austria
| | - Helge Rask‐Andersen
- Departments of OtolaryngologyUppsala University Hospital751 85Uppsala Sweden
| | - Michael J. F. Blumer
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional AnatomyMedical University of InnsbruckMüllerstrasse 596020Innsbruck Austria
| | | | - Helga Fritsch
- Department of Anatomy, Histology, and Embryology, Division of Clinical and Functional AnatomyMedical University of InnsbruckMüllerstrasse 596020Innsbruck Austria
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Shi F, Edge ASB. Prospects for replacement of auditory neurons by stem cells. Hear Res 2013; 297:106-12. [PMID: 23370457 DOI: 10.1016/j.heares.2013.01.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/16/2013] [Accepted: 01/18/2013] [Indexed: 02/07/2023]
Abstract
Sensorineural hearing loss is caused by degeneration of hair cells or auditory neurons. Spiral ganglion cells, the primary afferent neurons of the auditory system, are patterned during development and send out projections to hair cells and to the brainstem under the control of largely unknown guidance molecules. The neurons do not regenerate after loss and even damage to their projections tends to be permanent. The genesis of spiral ganglion neurons and their synapses forms a basis for regenerative approaches. In this review we critically present the current experimental findings on auditory neuron replacement. We discuss the latest advances with a focus on (a) exogenous stem cell transplantation into the cochlea for neural replacement, (b) expression of local guidance signals in the cochlea after loss of auditory neurons, (c) the possibility of neural replacement from an endogenous cell source, and (d) functional changes from cell engraftment.
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Affiliation(s)
- Fuxin Shi
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, USA
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14
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Water channel proteins in the inner ear and their link to hearing impairment and deafness. Mol Aspects Med 2012; 33:612-37. [DOI: 10.1016/j.mam.2012.06.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/11/2012] [Accepted: 06/17/2012] [Indexed: 11/24/2022]
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15
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Inner hair cells of mice express the glutamine transporter SAT1. Hear Res 2012; 292:59-63. [DOI: 10.1016/j.heares.2012.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 07/11/2012] [Accepted: 07/14/2012] [Indexed: 11/18/2022]
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16
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Attias J, Raveh E, Aizer-Dannon A, Bloch-Mimouni A, Fattal-Valevski A. Auditory System Dysfunction due to Infantile Thiamine Deficiency: Long-Term Auditory Sequelae. ACTA ACUST UNITED AC 2012; 17:309-20. [DOI: 10.1159/000339356] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 04/19/2012] [Indexed: 01/19/2023]
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17
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Uchida Y, Sugiura S, Ando F, Nakashima T, Shimokata H. Molecular genetic epidemiology of age-related hearing impairment. Auris Nasus Larynx 2011; 38:657-65. [PMID: 21601397 DOI: 10.1016/j.anl.2011.02.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 12/11/2022]
Abstract
Genetic epidemiology focuses on the genetic determinants in the etiology of disease among populations and seeks to elucidate the role of genetic factors and their interaction with environmental factors in disease occurrence. In recent years, genetic epidemiological research has become more focused on complex diseases, and human genome analysis technology has made remarkable advances. Age-related hearing impairment (ARHI) is a complex trait, which results from a multitude of confounding intrinsic and extrinsic factors. Although the number of genetic investigations of ARHI is increasing at a surprising rate, the etiology of ARHI is not firmly established. In this article, we review (1) the methodological strategies used to analyze genetic factors that contribute to human ARHI, (2) several representative investigations, and (3) specific genetic risk factors for human ARHI identified in previous work.
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Affiliation(s)
- Yasue Uchida
- Department of Otorhinolaryngology, National Center for Geriatrics and Gerontology, Japan.
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18
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The mouse cochlea expresses a local hypothalamic-pituitary-adrenal equivalent signaling system and requires corticotropin-releasing factor receptor 1 to establish normal hair cell innervation and cochlear sensitivity. J Neurosci 2011; 31:1267-78. [PMID: 21273411 DOI: 10.1523/jneurosci.4545-10.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cells of the inner ear face constant metabolic and structural stress. Exposure to intense sound or certain drugs destroys cochlea hair cells, which in mammals do not regenerate. Thus, an endogenous stress response system may exist within the cochlea to protect it from everyday stressors. We recently described the existence of corticotropin-releasing factor (CRF) in the mouse cochlea. The CRF receptor type 1 (CRFR1) is considered the primary and canonical target of CRF signaling, and systemically it plays an essential role in coordinating the body-wide stress response via activation of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we describe an essential role for CRFR1 in auditory system development and function, and offer the first description of a complete HPA equivalent signaling system resident within the cochlea. To reveal the role of CRFR1 activation in the cochlea, we have used mice carrying a null ablation of the CRFR1 gene. CRFR1(-/-) mice exhibited elevated auditory thresholds at all frequencies tested, indicating reduced sensitivity. Furthermore, our results suggest that CRFR1 has a developmental role affecting inner hair cell morphology and afferent and efferent synapse distribution. Given the role of HPA signaling in maintaining local homeostasis in other tissues, the presence of a cochlear HPA signaling system suggests important roles for CRFR1 activity in setting cochlear sensitivity, perhaps both neural and non-neural mechanisms. These data highlight the complex pleiotropic mechanisms modulated by CRFR1 signaling in the cochlea.
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Alesutan I, Sopjani M, Munoz C, Fraser S, Kemp BE, Föller M, Lang F. Inhibition of Connexin 26 by the AMP-Activated Protein Kinase. J Membr Biol 2011; 240:151-8. [DOI: 10.1007/s00232-011-9353-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 02/22/2011] [Indexed: 01/19/2023]
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Maeda Y, Fukushima K, Hirai M, Kariya S, Smith RJH, Nishizaki K. Microarray analysis of the effect of dexamethasone on murine cochlear explants. Acta Otolaryngol 2010; 130:1329-34. [PMID: 20735180 DOI: 10.3109/00016489.2010.498836] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONCLUSIONS The microarray analysis identified 39 genes up- or down-regulated by dexamethasone in the cultured tissue of mice cochlea. Of the eight genes most highly affected, several are suggested to have protective effects in the traumatized inner ear (Fkbp5, Glucocorticoid-induced leucine zipper (Gilz), glutathione peroxidase 3) and for others, a plausible mechanism of action can be offered (claudin 10, glutamate-ammonia ligase). The present data may support the use of dexamethasone to treat acute sensorineural hearing loss. It is warrantable to test these results in the in vivo cochlea. OBJECTIVES To identify genes whose expression is markedly up- or down-regulated by dexamethasone in the cochlear tissue. METHODS Murine cochlear tissue was cultured with or without dexamethasone for 48 h in vitro. The gene expression profiles were compared between the dexamethasone-treated and untreated cochlear tissue using a microarray that covers 33 696 transcripts (24 878 genes) of mice and quantitative real-time RT-PCR. RESULTS The microarray analysis identified 39 genes that are up- or down-regulated by more than twofold in the presence of dexamethasone in the cochlear culture. Genes up- or down-regulated by at least threefold include Fkbp5, Gilz, glutathione peroxidase 3, claudin 10, glutamate-ammonia ligase, proteoglycan 1, integrin beta-like 1, and alpha subunit of glycoprotein hormone.
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Affiliation(s)
- Yukihide Maeda
- Department of Otolaryngology - Head and Neck Surgery, Okayama University Graduate School of Medicine, Okayama, Japan.
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21
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Friedman RA, Van Laer L, Huentelman MJ, Sheth SS, Van Eyken E, Corneveaux JJ, Tembe WD, Halperin RF, Thorburn AQ, Thys S, Bonneux S, Fransen E, Huyghe J, Pyykkö I, Cremers CWRJ, Kremer H, Dhooge I, Stephens D, Orzan E, Pfister M, Bille M, Parving A, Sorri M, Van de Heyning PH, Makmura L, Ohmen JD, Linthicum FH, Fayad JN, Pearson JV, Craig DW, Stephan DA, Van Camp G. GRM7 variants confer susceptibility to age-related hearing impairment. Hum Mol Genet 2009; 18:785-96. [PMID: 19047183 PMCID: PMC2638831 DOI: 10.1093/hmg/ddn402] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 11/20/2008] [Indexed: 01/22/2023] Open
Abstract
Age-related hearing impairment (ARHI), or presbycusis, is the most prevalent sensory impairment in the elderly. ARHI is a complex disease caused by an interaction between environmental and genetic factors. Here we describe the results of the first whole genome association study for ARHI. The study was performed using 846 cases and 846 controls selected from 3434 individuals collected by eight centers in six European countries. DNA pools for cases and controls were allelotyped on the Affymetrix 500K GeneChip for each center separately. The 252 top-ranked single nucleotide polymorphisms (SNPs) identified in a non-Finnish European sample group (1332 samples) and the 177 top-ranked SNPs from a Finnish sample group (360 samples) were confirmed using individual genotyping. Subsequently, the 23 most interesting SNPs were individually genotyped in an independent European replication group (138 samples). This resulted in the identification of a highly significant and replicated SNP located in GRM7, the gene encoding metabotropic glutamate receptor type 7. Also in the Finnish sample group, two GRM7 SNPs were significant, albeit in a different region of the gene. As the Finnish are genetically distinct from the rest of the European population, this may be due to allelic heterogeneity. We performed histochemical studies in human and mouse and showed that mGluR7 is expressed in hair cells and in spiral ganglion cells of the inner ear. Together these data indicate that common alleles of GRM7 contribute to an individual's risk of developing ARHI, possibly through a mechanism of altered susceptibility to glutamate excitotoxicity.
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Affiliation(s)
- Rick A Friedman
- House Ear Institute, Gonda Research Center for Cell and Molecular Biology, Los Angeles, CA, USA.
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Lang F, Vallon V, Knipper M, Wangemann P. Functional significance of channels and transporters expressed in the inner ear and kidney. Am J Physiol Cell Physiol 2007; 293:C1187-208. [PMID: 17670895 DOI: 10.1152/ajpcell.00024.2007] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A number of ion channels and transporters are expressed in both the inner ear and kidney. In the inner ear, K+cycling and endolymphatic K+, Na+, Ca2+, and pH homeostasis are critical for normal organ function. Ion channels and transporters involved in K+cycling include K+channels, Na+-2Cl−-K+cotransporter, Na+/K+-ATPase, Cl−channels, connexins, and K+/Cl−cotransporters. Furthermore, endolymphatic Na+and Ca2+homeostasis depends on Ca2+-ATPase, Ca2+channels, Na+channels, and a purinergic receptor channel. Endolymphatic pH homeostasis involves H+-ATPase and Cl−/HCO3−exchangers including pendrin. Defective connexins (GJB2 and GJB6), pendrin (SLC26A4), K+channels (KCNJ10, KCNQ1, KCNE1, and KCNMA1), Na+-2Cl−-K+cotransporter (SLC12A2), K+/Cl−cotransporters (KCC3 and KCC4), Cl−channels (BSND and CLCNKA + CLCNKB), and H+-ATPase (ATP6V1B1 and ATPV0A4) cause hearing loss. All these channels and transporters are also expressed in the kidney and support renal tubular transport or signaling. The hearing loss may thus be paralleled by various renal phenotypes including a subtle decrease of proximal Na+-coupled transport (KCNE1/KCNQ1), impaired K+secretion (KCNMA1), limited HCO3−elimination (SLC26A4), NaCl wasting (BSND and CLCNKB), renal tubular acidosis (ATP6V1B1, ATPV0A4, and KCC4), or impaired urinary concentration (CLCNKA). Thus, defects of channels and transporters expressed in the kidney and inner ear result in simultaneous dysfunctions of these seemingly unrelated organs.
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Affiliation(s)
- Florian Lang
- Department of Physiology, Eberhard-Karls-University of Tübingen, Gmelinstrasse 5, Tübingen, Germany.
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Anne S, Kisley LB, Tajuddin ST, Leahy P, Alagramam KN, Megerian CA. Molecular Changes Associated With the Endolymphatic Hydrops Model. Otol Neurotol 2007; 28:834-41. [PMID: 17468674 DOI: 10.1097/mao.0b013e3180515381] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS Hearing loss and cochlear degeneration in the guinea pig model of endolymphatic hydrops (ELH) results, in part, from toxic levels of excitatory amino acids (EAAs) such as glutamate, which in turn leads to changes in the expression of genes linked to intracellular glutamate homeostasis and apoptosis, leading to neuronal cell death. BACKGROUND EAAs have been shown to play a role in normal auditory signal transmission in mammalian cochlea, but have also been implicated in neurotoxicity when levels are elevated. Changes in the expression of specific genes involved in the glutamatergic and apoptotic pathway would serve as evidence for excitotoxicity linked to elevated levels of glutamate. METHODS Guinea pigs underwent surgical obliteration of the endolymphatic duct, and then a timed harvest of the treated (right) and control (left) cochlea and subsequent quantification of gene expression via real-time quantitative polymerase chain reaction. RESULTS Quantitative polymerase chain reaction data show significant upregulation of glutamate aspartate transporter and neuronal nitric oxide synthase mRNA levels 3 weeks postsurgery and Caspase 3 mRNA levels 1 week postsurgery. No significant changes were detected in glutamine synthetase expression levels. CONCLUSION Upregulation of genes involved in glutamate homeostasis and the apoptotic pathway in animals treated with endolymphatic duct obstruction (usually associated with secondary ELH) support the hypothesis that EAAs may play a role in the pathophysiology of ELH-related cochlear injury. Inhibitors to these pathways can be useful for the study of new avenues to delay or prevent ELH-related hearing loss.
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Affiliation(s)
- Samantha Anne
- Otolaryngology-Head and Neck Surgery, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106, USA
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24
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Wangemann P. Supporting sensory transduction: cochlear fluid homeostasis and the endocochlear potential. J Physiol 2006; 576:11-21. [PMID: 16857713 PMCID: PMC1995626 DOI: 10.1113/jphysiol.2006.112888] [Citation(s) in RCA: 330] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 07/14/2006] [Indexed: 12/13/2022] Open
Abstract
The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endocochlear potential and requires a highly specialized environment that enables and sustains sensory function. Disturbance of cochlear homeostasis is the cause of many forms of hearing loss including the most frequently occurring syndromic and non-syndromic forms of hereditary hearing loss, Pendred syndrome and Cx26-related deafness. The occurrence of these and other monogenetic disorders illustrates that cochlear fluid homeostasis and the generation of the endocochlear potential are poorly secured by functional redundancy. This review summarizes the most prominent aspects of cochlear fluid homeostasis. It covers cochlear fluid composition, the generation of the endocochlear potential, K(+) secretion and cycling and its regulation, the role of gap junctions, mechanisms of acid-base homeostasis, and Ca(2+) transport.
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Affiliation(s)
- Philine Wangemann
- Anatomy & Physiology Department, 205 Coles Hall, Kansas State University, Manhattan, 66506, USA.
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Mazurek B, Winter E, Fuchs J, Haupt H, Gross J. Susceptibility of the hair cells of the newborn rat cochlea to hypoxia and ischemia. Hear Res 2003; 182:2-8. [PMID: 12948595 DOI: 10.1016/s0378-5955(03)00134-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Hypoxia and ischemia are thought to be important pathogenetic factors in bringing about hearing loss. In order to study the effect of these determinants on the loss of inner and outer hair cells (IHCs/OHCs), we used an in vitro hypoxia and ischemia model of the newborn rat cochlea. The specimens of the organ of Corti were exposed either to hypoxia (10-20 mm Hg) or to normoxic glucose deprivation or to both (ischemia) in artificial perilymph for different exposure periods. The number of IHCs and OHCs was counted and the hair cell loss was compared to controls. Normoxic aglycemia did not cause significant hair cell loss as compared to controls. Hypoxia and ischemia led to hair cell loss in a dose-dependent manner, with the loss in the ischemia groups found to be markedly higher than that in the hypoxia groups. Hypoxia resulted in a mean loss of 8% OHC and of 14% IHC after an 8-h exposure. Ischemia increased the loss to 19% OHC and 39% IHC after the same exposure period of 8 h. Our findings suggest that IHCs are more susceptible to hypoxia/ischemia than OHCs.
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Affiliation(s)
- Birgit Mazurek
- Molecular-Biological Research Laboratory, Department of Otorhinolaryngology, Charité Hospital, Humboldt University, Spandauer Damm 130, Bld. 31, 14050 Berlin, Germany
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Abstract
The role of the cochlea is to transduce complex sound waves into electrical neural activity in the auditory nerve. Hair cells of the organ of Corti are the sensory cells of hearing. The inner hair cells perform the transduction and initiate the depolarization of the spiral ganglion neurons. The outer hair cells are accessory sensory cells that enhance the sensitivity and selectivity of the cochlea. Neural feedback loops that bring efferent signals to the outer hair cells assist in sharpening and amplifying the signals. The stria vascularis generates the endocochlear potential and maintains the ionic composition of the endolymph, the fluid in which the apical surface of the hair cells is bathed. The mechanical characteristics of the basilar membrane and its related structures further enhance the frequency selectivity of the auditory transduction mechanism. The tectorial membrane is an extracellular matrix, which provides mass loading on top of the organ of Corti, facilitating deflection of the stereocilia. This review deals with the structure of the normal mature mammalian cochlea and includes recent data on the molecular organization of the main cell types within the cochlea.
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Affiliation(s)
- Yehoash Raphael
- Kresge Hearing Research Institute, The University of Michigan, MSRB 3, Rm 9303, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0648, USA.
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27
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Rebillard G, Ruel J, Nouvian R, Saleh H, Pujol R, Dehnes Y, Raymond J, Puel JL, Devau G. Glutamate transporters in the guinea-pig cochlea: partial mRNA sequences, cellular expression and functional implications. Eur J Neurosci 2003; 17:83-92. [PMID: 12534971 DOI: 10.1046/j.1460-9568.2003.02429.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the cochlea, glutamate plays a major role in synaptic transmission between the inner hair cell and the primary auditory neurons. Extracellular glutamate concentration must be regulated to prevent excitotoxicity. This regulation is mediated by excitatory amino acid transporters, membrane proteins that remove glutamate from the synaptic cleft. In this study, we investigated the distribution and activity of three excitatory amino acid transporters subtypes in the guinea-pig cochlea: glutamate aspartate transporter, glutamate transporter and excitatory amino acid carrier. A partial messenger ribonucleic acid sequence was determined for each of these transporters, by polymerase chain reaction with degenerate primers, using guinea-pig brain complementary deoxyribonucleic acid as the template. Primers specific for each transporter were then designed and used to screen a dissected organ of Corti complementary deoxyribonucleic acid library. The cellular distribution of each transporter was examined by immunocytochemistry. We investigated the functional consequences of inhibiting glutamate uptake by recording cochlear potentials during intracochlear perfusion with either l-trans-pyrrolidine-2,4-dicarboxylic acid or dihydrokainate. At the end of the electrophysiological session, cochleas were processed for electron microscopy. Only the glutamate aspartate transporter messenger ribonucleic acid was detected in the organ of Corti. Consistently, glutamate aspartate transporter protein was detected in the inner hair cell-supporting cells and in the ganglion of Corti satellite cells. Glutamate transporter and excitatory amino acid carrier were found in the afferent auditory neurons. Only intracochlear perfusions with l-trans-pyrrolidine-2,4-dicarboxylic acid resulted in a dose-dependent decrease in the amplitude of the cochlear compound action potential, leaving cochlear microphonic potential unaffected. After l-trans-pyrrolidine-2,4-dicarboxylic acid perfusion, cochleas displayed a swelling of the afferent endings typical of excitotoxicity. [(-)1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-4,5-dihydro-3-methylcarbamyl-2,3-benzodiazepine], a selective alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist protects the cochlea against l-trans-pyrrolidine-2,4-dicarboxylic acid effect.
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Affiliation(s)
- G Rebillard
- Inserm U 254, Université Montpellier I, Neurobiologie de l'audition - Plasticité synaptique, 71, rue de Navacelles 34090 Montpellier, France
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28
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Miller KE, Richards BA, Kriebel RM. Glutamine-, glutamine synthetase-, glutamate dehydrogenase- and pyruvate carboxylase-immunoreactivities in the rat dorsal root ganglion and peripheral nerve. Brain Res 2002; 945:202-11. [PMID: 12126882 DOI: 10.1016/s0006-8993(02)02802-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Supporting glial cells of the peripheral nervous system include satellite cells of dorsal root ganglia and Schwann cells of peripheral nerves. In the central nervous system, glial cells contain enzymes related to the tricarboxylic acid and glutamine cycles: pyruvate carboxylase, glutamate dehydrogenase, and glutamine synthetase. The present study used immunohistochemistry in the rat peripheral nervous system to determine the cellular distribution of these enzymes along with glutamine. In dorsal root ganglia and peripheral nerves, glutamine and glutamine related enzymes were enriched in satellite and Schwann cells. In the dorsal root ganglia, immunoreactive satellite cells surrounded neurons of all sizes. In peripheral nerve, immunoreactive Schwann cells were most easily observed surrounding large diameter, myelinated axons. These Schwann cells contained immunoreactivity in their cell bodies, nodes of Ranvier, and the rim of cytoplasm outside the myelin sheath. Myelin sheaths were non-immunoreactive. The peripheral glial tricarboxylic and glutamine cycles may be used to produce glutamine for neuronal cell uptake and conversion to glutamate for synaptic transmission. Alternatively, these cycles may function in peripheral glia similar to central nervous system astrocytes for supporting the energy demands of neurons.
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Affiliation(s)
- Kenneth E Miller
- Department of Cell Biology, BMSB 562, University of Oklahoma Health Sciences Center, 940 S.L. Young Blvd., Oklahoma City, OK 73190, USA.
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29
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Chapter IX Glutamate neurotransmission in the mammalian inner ear. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0924-8196(00)80050-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Furness DN, Lehre KP. Immunocytochemical localization of a high-affinity glutamate-aspartate transporter, GLAST, in the rat and guinea-pig cochlea. Eur J Neurosci 1997; 9:1961-9. [PMID: 9383219 DOI: 10.1111/j.1460-9568.1997.tb00763.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glutamate transporters play an important role in the reuptake of glutamate after its release from glutamatergic synapses. Four such transporters have so far been cloned from the rat brain. One, the glutamate-aspartate transporter GLAST, has been detected in the mammalian cochlea, in which the principal afferent synapse of the auditory nerve, between the inner hair cells and neurites of type I spiral ganglion neurons, has been suggested to be glutamatergic. The distribution of GLAST was therefore investigated to provide clues to the handling of glutamate in the cochlea. This was studied using light and electron microscopic immunocytochemistry in rats and guinea pigs with antibodies raised against synthetic peptides based on the sequence for GLAST. Significant immunoreactivity was found in the myelin sheath formed by satellite cells surrounding the type I spiral ganglion neurons, and along the plasma membranes of supporting cells around the inner hair cells; other cells in both locations were only weakly labelled, if at all. The absence of substantial numbers of synapses in the spiral ganglion suggests that GLAST is unlikely to be associated with the uptake of synaptic glutamate after release in this region. Immunoreactivity associated with the inner hair cells is consistent with the utilization of glutamate at the afferent synapse.
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Affiliation(s)
- D N Furness
- Department of Communication and Neuroscience, Keele University, Staffordshire, UK
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