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Sohel MSH, Atoji Y, Onouchi S, Saito S. Expression patterns of prosaposin and neurotransmitter-related molecules in the chick paratympanic organ. Tissue Cell 2023; 83:102130. [PMID: 37320868 DOI: 10.1016/j.tice.2023.102130] [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: 05/02/2023] [Revised: 06/01/2023] [Accepted: 06/08/2023] [Indexed: 06/17/2023]
Abstract
The paratympanic organ (PTO) is a small sense organ in the middle ear of birds that contains hair cells similar to those found in vestibuloauditory organs and receives afferent fibers from the geniculate ganglion. To consider the histochemical similarities between the PTO and vestibular hair cells, we examined the expression patterns of representative molecules in vestibular hair cells, including prosaposin, G protein-coupled receptor (GPR) 37 and GPR37L1 as prosaposin receptors, vesicular glutamate transporter (vGluT) 2 and vGluT3, nicotinic acetylcholine receptor subunit α9 (nAChRα9), and glutamic acid decarboxylase (GAD) 65 and GAD67, in the postnatal day 0 chick PTO and geniculate ganglion by in situ hybridization. Prosaposin mRNA was observed in PTO hair cells, supporting cells, and geniculate ganglion cells. vGluT3 mRNA was observed in PTO hair cells, whereas vGluT2 was observed in a small number of ganglion cells. nAChRα9 mRNA was observed in a small number of PTO hair cells. The results suggest that the histochemical character of PTO hair cells is more similar to that of vestibular hair cells than that of auditory hair cells in chicks.
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Affiliation(s)
- Md Shahriar Hasan Sohel
- Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yasuro Atoji
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Sawa Onouchi
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Shouichiro Saito
- Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
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2
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Liu H, Liu H, Wang L, Song L, Jiang G, Lu Q, Yang T, Peng H, Cai R, Zhao X, Zhao T, Wu H. Cochlear transcript diversity and its role in auditory functions implied by an otoferlin short isoform. Nat Commun 2023; 14:3085. [PMID: 37248244 DOI: 10.1038/s41467-023-38621-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 05/10/2023] [Indexed: 05/31/2023] Open
Abstract
Isoforms of a gene may contribute to diverse biological functions. In the cochlea, the repertoire of alternative isoforms remains unexplored. We integrated single-cell short-read and long-read RNA sequencing techniques and identified 236,012 transcripts, 126,612 of which were unannotated in the GENCODE database. Then we analyzed and verified the unannotated transcripts using RNA-seq, RT-PCR, Sanger sequencing, and MS-based proteomics approaches. To illustrate the importance of identifying spliced isoforms, we investigated otoferlin, a key protein involved in synaptic transmission in inner hair cells (IHCs). Upon deletion of the canonical otoferlin isoform, the identified short isoform is able to support normal hearing thresholds but with reduced sustained exocytosis of IHCs, and further revealed otoferlin functions in endocytic membrane retrieval that was not well-addressed previously. Furthermore, we found that otoferlin isoforms are associated with IHC functions and auditory phenotypes. This work expands our mechanistic understanding of auditory functions at the level of isoform resolution.
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Affiliation(s)
- Huihui Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hongchao Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Longhao Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Guixian Jiang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Qing Lu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Tao Yang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hu Peng
- Department of Otolaryngology-Head and Neck Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Ruijie Cai
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Xingle Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Ting Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China.
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3
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Anastasios G, Magioula G, Konstantinos K, Ioannis A. Noise and Health: Review. Indian J Otolaryngol Head Neck Surg 2022; 74:5482-5491. [PMID: 36742745 PMCID: PMC9895353 DOI: 10.1007/s12070-021-02797-1] [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: 06/04/2021] [Accepted: 08/01/2021] [Indexed: 02/07/2023] Open
Abstract
Noise in human societies is unavoidable, but it tends to become a modern epidemic that induces various detrimental effects to several organs and functions in humans. Increased cardiovascular danger, anxiety and sleep disturbance are just few of these effects. It is noteworthy that children, even neonates and their developing organism are especially vulnerable to noise-related health problems. Noise is measured with special noise-meters. These devices express results in decibels by transforming random noise to a continuous sound. This sound is characterized by equivalent acoustic energy to the random noise for a defined time interval. Human auditory apparatus is principally endangered by acute noises but also by chronic noise exposure, in the context of both occupational and recreational activities. Various mechanisms are implicated in the pathogenesis of noise-induced hearing loss that can cause either temporary or permanent damage. Among them, emphasis is given to the impairment by free radicals and inflammatory mediators, to the activation of apoptotic molecular pathways, but also to glutamate excitotoxicity. A hidden hearing loss, synaptopathy, is attributed to the latter. The irreversible nature of hearing loss, as well as the idiosyncratic sensitivity of individuals, imposes the necessity of early diagnosis of auditory impairment by noise. Super high frequency audiograms, otoacoustic emissions and electrophysiological examinations can address diagnosis. Thankfully, there is extensive research on acoustic trauma therapeutic approaches. However, until we succeed in regenerating the sensory organ of hearing, chronic noise-induced hearing loss cannot be treated. Thus, it is fundamental that society protects people from noise, by laws and regulations.
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Affiliation(s)
- Goulioumis Anastasios
- Department of Otorhinolaryngology, Pediatric Hospital “Karamandanio”, Patras, Greece
| | | | - Kourelis Konstantinos
- Department of Otorhinolaryngology, Pediatric Hospital “Karamandanio”, Patras, Greece
| | - Athanasopoulos Ioannis
- Department of Otorhinolaryngology, Pediatric Center of “Iatriko Athinon” Hospital, Athens, Greece
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4
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Kitcher SR, Pederson AM, Weisz CJC. Diverse identities and sites of action of cochlear neurotransmitters. Hear Res 2021; 419:108278. [PMID: 34108087 DOI: 10.1016/j.heares.2021.108278] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/30/2021] [Accepted: 05/18/2021] [Indexed: 11/18/2022]
Abstract
Accurate encoding of acoustic stimuli requires temporally precise responses to sound integrated with cellular mechanisms that encode the complexity of stimuli over varying timescales and orders of magnitude of intensity. Sound in mammals is initially encoded in the cochlea, the peripheral hearing organ, which contains functionally specialized cells (including hair cells, afferent and efferent neurons, and a multitude of supporting cells) to allow faithful acoustic perception. To accomplish the demanding physiological requirements of hearing, the cochlea has developed synaptic arrangements that operate over different timescales, with varied strengths, and with the ability to adjust function in dynamic hearing conditions. Multiple neurotransmitters interact to support the precision and complexity of hearing. Here, we review the location of release, action, and function of neurotransmitters in the mammalian cochlea with an emphasis on recent work describing the complexity of signaling.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Alia M Pederson
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Catherine J C Weisz
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States.
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5
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Kohrman DC, Borges BC, Cassinotti LR, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 DOI: 10.1002/dneu.22813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [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 C Kohrman
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Beatriz C Borges
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Luis R Cassinotti
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Lingchao Ji
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gabriel Corfas
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
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6
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Sánchez-Benito D, Hyppolito MA, Alvarez-Morujo AJ, López DE, Gómez-Nieto R. Morphological and molecular correlates of altered hearing sensitivity in the genetically audiogenic seizure-prone hamster GASH/Sal. Hear Res 2020; 392:107973. [PMID: 32402894 DOI: 10.1016/j.heares.2020.107973] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/30/2020] [Accepted: 04/07/2020] [Indexed: 02/08/2023]
Abstract
Rodent models of audiogenic seizures, in which seizures are precipitated by an abnormal response of the brain to auditory stimuli, are crucial to investigate the neural bases underlying ictogenesis. Despite significant advances in understanding seizure generation in the inferior colliculus, namely the epileptogenic nucleus, little is known about the contribution of lower auditory stations to the seizure-prone network. Here, we examined the cochlea and cochlear nucleus of the genetic audiogenic seizure hamster from Salamanca (GASH/Sal), a model of reflex epilepsy that exhibits generalized tonic-clonic seizures in response to loud sound. GASH/Sal animals under seizure-free conditions were compared with matched control hamsters in a multi-technical approach that includes auditory brainstem responses (ABR) testing, histology, scanning electron microscopy analysis, immunohistochemistry, quantitative morphometry and gene expression analysis (RT-qPCR). The cochlear histopathology of the GASH/Sal showed preservation of the sensory hair cells, but a significant loss of spiral ganglion neurons and mild atrophy of the stria vascularis. At the electron microscopy level, the reticular lamina exhibited disarray of stereociliary tufts with blebs, loss or elongated stereocilia as well as non-parallel rows of outer hair cells due to protrusions of Deiters' cells. At the molecular level, the abnormal gene expression patterns of prestin, cadherin 23, protocadherin 15, vesicular glutamate transporters 1 (Vglut1) and -2 (Vglut2) indicated that the hair-cell mechanotransduction and cochlear amplification were markedly altered. These were manifestations of a cochlear neuropathy that correlated to ABR waveform I alterations and elevated auditory thresholds. In the cochlear nucleus, the distribution of VGLUT2-immunolabeled puncta was differently affected in each subdivision, showing significant increases in magnocellular regions of the ventral cochlear nucleus and drastic reductions in the granule cell domain. This modified inputs lead to disruption of Vglut1 and Vglut2 gene expression in the cochlear nucleus. In sum, our study provides insight into the morphological and molecular traits associated with audiogenic seizure susceptibility in the GASH/Sal, suggesting an upward spread of abnormal glutamatergic transmission throughout the primary acoustic pathway to the epileptogenic region.
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Affiliation(s)
- David Sánchez-Benito
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain
| | - Miguel A Hyppolito
- Laboratory of Neurobiology of Hearing, Department of Ophthalmology, Otorhinolaryngology, Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Antonio J Alvarez-Morujo
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
| | - Dolores E López
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
| | - Ricardo Gómez-Nieto
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain.
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7
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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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Fuentes-Santamaría V, Alvarado JC, Rodríguez-de la Rosa L, Juiz JM, Varela-Nieto I. Neuroglial Involvement in Abnormal Glutamate Transport in the Cochlear Nuclei of the Igf1 -/- Mouse. Front Cell Neurosci 2019; 13:67. [PMID: 30881288 PMCID: PMC6405628 DOI: 10.3389/fncel.2019.00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/11/2019] [Indexed: 12/25/2022] Open
Abstract
Insulin-like growth factor 1 (IGF-1) is a powerful regulator of synaptic activity and a deficit in this protein has a profound impact on neurotransmission, mostly on excitatory synapses in both the developing and mature auditory system. Adult Igf1−/− mice are animal models for the study of human syndromic deafness; they show altered cochlear projection patterns into abnormally developed auditory neurons along with impaired glutamate uptake in the cochlear nuclei, phenomena that probably reflect disruptions in neuronal circuits. To determine the cellular mechanisms that might be involved in regulating excitatory synaptic plasticity in 4-month-old Igf1−/− mice, modifications to neuroglia, astroglial glutamate transporters (GLTs) and metabotropic glutamate receptors (mGluRs) were assessed in the cochlear nuclei. The Igf1−/− mice show significant decreases in IBA1 (an ionized calcium-binding adapter) and glial fibrillary acidic protein (GFAP) mRNA expression and protein accumulation, as well as dampened mGluR expression in conjunction with enhanced glutamate transporter 1 (GLT1) expression. By contrast, no differences were observed in the expression of glutamate aspartate transporter (GLAST) between these Igf1−/− mice and their heterozygous or wildtype littermates. These observations suggest that congenital IGF-1 deficiency may lead to alterations in microglia and astrocytes, an upregulation of GLT1, and the downregulation of groups I, II and III mGluRs. Understanding the molecular, biochemical and morphological mechanisms underlying neuronal plasticity in a mouse model of hearing deficits will give us insight into new therapeutic strategies that could help to maintain or even improve residual hearing when human deafness is related to IGF-1 deficiency.
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Affiliation(s)
- Veronica Fuentes-Santamaría
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Juan C Alvarado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Lourdes Rodríguez-de la Rosa
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), CIBER MP, Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - José M Juiz
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Isabel Varela-Nieto
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), CIBER MP, Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
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Wang J, Yin S, Chen H, Shi L. Noise-Induced Cochlear Synaptopathy and Ribbon Synapse Regeneration: Repair Process and Therapeutic Target. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1130:37-57. [PMID: 30915700 DOI: 10.1007/978-981-13-6123-4_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The synapse between the inner hair cells (IHCs) and the spiral ganglion neurons (SGNs) in mammalian cochleae is characterized as having presynaptic ribbons and therefore is called ribbon synapse. The special molecular organization is reviewed in this chapter in association with the functional feature of this synapse in signal processing. This is followed by the review on noise-induced damage to this synapse with a focus on recent reports in animal models in which the effect of brief noise exposures is observed without causing significant permanent threshold shift (PTS). In this regard, the potential mechanism of the synaptic damage by noise and the impact of this damage on hearing are summarized to clarify the concept of noise-induced hidden hearing loss, which is defined as the functional deficits in hearing without threshold elevation. A controversial issue is addressed in this review as whether the disrupted synapses can be regenerated. Moreover, the review summarizes the work of therapeutic research to protect the synapses or to promote the regeneration of the synapse after initial disruption. Lastly, several unresolved issues are raised for investigation in the future.
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Affiliation(s)
- Jian Wang
- School of Communication Science and Disorders, Dalhousie University, Halifax, NS, Canada.
| | - Shankai Yin
- Otolaryngology Research Institute, 6th Affiliated Hospital, Shanghai Jiao-Tong University, Shanghai, China
| | - Hengchao Chen
- Otolaryngology Research Institute, 6th Affiliated Hospital, Shanghai Jiao-Tong University, Shanghai, China
| | - Lijuan Shi
- Department of Physiology, Medical College of Southeast University, Nanjing, China
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10
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Li Y, Zou Q, Zhang J. Vincamine exerts protective effect on spiral ganglion neurons in endolymphatic hydrops guinea pig models. Am J Transl Res 2018; 10:3650-3663. [PMID: 30662616 PMCID: PMC6291722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 10/16/2018] [Indexed: 06/09/2023]
Abstract
The aim of this study was to investigate the protective effects of vincamine in endolymphatic hydrops (ELH). After ELH guinea pigs treated by vincamine, the concentration of VAP in plasma, and the levels of cAMP, MDA, SOD, GSH-Px in right cochlea were measured using spectrophotometric method. The V2R, NMDAR1, p-NMDAR1, AQP2, p-AQP2, caspase3/9 and c-caspase3/9 expressions in right cochlea were detected using western blot analysis. The cochlear hydrops degree and SGNs density were evaluated by hemotoxylin and eosin staining (HE) test. Normal hearing and vestibular function were warranted by the tests of auditory brainstem response (ABR) and electronystagmography (ENG). After glutamate-injured SGNs treated with vincamine, the MDA, SOD GSH-Px, NGF, BDNF, NT3, NT4 and Trks levels were measured. Meanwhile, the Bcl2, Bax, NMDAR1, p-NMDAR1, PI3K, p-PI3K, Akt, p-Akt, caspase3/9 and cleaved-caspase3/9 expression levels were detected. Furthermore, the viability, apoptosis and necrosis of SGNs were tested by MTT and Hoechst/PI staining methods. The results indicated that vincamine could significantly inhibit the expression levels of cAMP, MDA, V2R, p-NMDAR1, p-AQP2 and c-caspase-3/-9 in cochlea, alleviate the cochlear hydrops degree, regulate the audiological and vestibular dysfunctions. The SGNs density, SOD and GSH-Px levels were also increased by vincamine. In vincamine-treating groups, the MDA, Bax, p-NMDAR1, and c-caspase3/9 levels were observably decreased, while SGNs survival, SOD, GSH, NGF, BDNF, NT3, NT4, Trks, Bcl2, p-PI3K, p-Akt expressions were improved. The present study indicated a novel use of vincamine in suppressing ELH formation by down-regulating the VAP/AQP2 signaling pathway. It also manifested that vincamine exerted protective effects on hearing via improving neurotrophin-dependent PI3K/Akt signaling pathway in SGNs.
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Affiliation(s)
- Yi Li
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Tongren HospitalBeijing 100730, China
| | - Qijuan Zou
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Tongren HospitalBeijing 100730, China
| | - Jie Zhang
- Shanghai University of TCMShanghai 201203, China
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11
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Sharma K, Seo YW, Yi E. Differential Expression of Ca 2+-buffering Protein Calretinin in Cochlear Afferent Fibers: A Possible Link to Vulnerability to Traumatic Noise. Exp Neurobiol 2018; 27:397-407. [PMID: 30429649 PMCID: PMC6221833 DOI: 10.5607/en.2018.27.5.397] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 09/28/2018] [Accepted: 10/02/2018] [Indexed: 12/18/2022] Open
Abstract
The synaptic contacts of cochlear afferent fibers (CAFs) with inner hair cells (IHCs) are spatially segregated according to their firing properties. CAFs also exhibit spatially segregated vulnerabilities to noise. The CAF fibers contacting the modiolar side of IHCs tend to be more vulnerable. Noise vulnerability is thought to be due to the absence of neuroprotective mechanisms in the modiolar side contacting CAFs. In this study, we investigated whether the expression of neuroprotective Ca2+-buffering proteins is spatially segregated in CAFs. The expression patterns of calretinin, parvalbumin, and calbindin were examined in rat CAFs using immunolabeling. Calretinin-rich fibers, which made up ~50% of the neurofilament (NF)-positive fibers, took the pillar side course and contacted all IHC sides. NF-positive and calretinin-poor fibers took the modiolar side pathway and contacted the modiolar side of IHCs. Both fiber categories juxtaposed the C-terminal binding protein 2 (CtBP2) puncta and were contacted by synaptophysin puncta. These results indicated that the calretinin-poor fibers, like the calretinin-rich ones, were afferent fibers and probably formed functional efferent synapses. However, the other Ca2+-buffering proteins did not exhibit CAF subgroup specificity. Most CAFs near IHCs were parvalbumin-positive. Only the pillar-side half of parvalbumin-positive fibers coexpressed calretinin. Calbindin was not detected in any nerve fibers near IHCs. Taken together, of the Ca2+-buffering proteins examined, only calretinin exhibited spatial segregation at IHC-CAF synapses. The absence of calretinin in modiolar-side CAFs might be related to the noise vulnerability of the fibers.
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Affiliation(s)
- Kushal Sharma
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Muan 58554, Korea
| | - Young-Woo Seo
- Korea Basic Science Institute Gwangju Center, Gwangju 61186, Korea
| | - Eunyoung Yi
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Muan 58554, Korea
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12
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Rossi ML, Rubbini G, Martini M, Canella R, Fesce R. Pre- and Postsynaptic Effects of Glutamate in the Frog Labyrinth. Neuroscience 2018; 385:198-214. [PMID: 29913242 DOI: 10.1016/j.neuroscience.2018.06.016] [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: 02/13/2018] [Revised: 06/06/2018] [Accepted: 06/08/2018] [Indexed: 11/20/2022]
Abstract
The role of glutamate in quantal release at the cytoneural junction was examined by measuring mEPSPs and afferent spikes at the posterior canal in the intact frog labyrinth. Release was enhanced by exogenous glutamate, or dl-TBOA, a blocker of glutamate reuptake. Conversely, drugs acting on ionotropic glutamate receptors did not affect release; the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) blocker CNQX decreased mEPSP size in a dose-dependent manner; the NMDA-R blocker d-AP5 at concentrations <200 µM did not affect mEPSP size, either in the presence or absence of Mg and glycine. In isolated hair cells, glutamate did not modify Ca currents. Instead, it systematically reduced the compound delayed potassium current, IKD, whereas the metabotropic glutamate receptor (mGluR)-II inverse agonist, (2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl)propanoic acid (LY341495), increased it. Given mGluR-II decrease cAMP production, these finding are consistent with the reported sensitivity of IKD to protein kinase A (PKA)-mediated phosphorylation. LY341495 also enhanced transmitter release, presumably through phosphorylation-mediated facilitation of the release machinery. The observed enhancement of release by glutamate confirms previous literature data, and can be attributed to activation of mGluR-I that promotes Ca release from intracellular stores. Glutamate-induced reduction in the repolarizing IKD may contribute to facilitation of release. Overall, glutamate exerts both a positive feedback action on mGluR-I, through activation of the phospholipase C (PLC)/IP3 path, and the negative feedback, by interfering with substrate phosphorylation through Gi/0-coupled mGluRs-II/III. The positive feedback prevails, which may explain the increase in overall rates of release observed during mechanical stimulation (symmetrical in the excitatory and inhibitory directions). The negative feedback may protect the junction from over-activation.
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Affiliation(s)
- Maria Lisa Rossi
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy.
| | - Gemma Rubbini
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Marta Martini
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Rita Canella
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Riccardo Fesce
- Centre of Neuroscience, DISTA, Insubria University, Varese, Italy
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13
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Liberman MC, Kujawa SG. Cochlear synaptopathy in acquired sensorineural hearing loss: Manifestations and mechanisms. Hear Res 2017; 349:138-147. [PMID: 28087419 PMCID: PMC5438769 DOI: 10.1016/j.heares.2017.01.003] [Citation(s) in RCA: 427] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 12/19/2016] [Accepted: 01/05/2017] [Indexed: 12/20/2022]
Abstract
Common causes of hearing loss in humans - exposure to loud noise or ototoxic drugs and aging - often damage sensory hair cells, reflected as elevated thresholds on the clinical audiogram. Recent studies in animal models suggest, however, that well before this overt hearing loss can be seen, a more insidious, but likely more common, process is taking place that permanently interrupts synaptic communication between sensory inner hair cells and subsets of cochlear nerve fibers. The silencing of affected neurons alters auditory information processing, whether accompanied by threshold elevations or not, and is a likely contributor to a variety of perceptual abnormalities, including speech-in-noise difficulties, tinnitus and hyperacusis. Work described here will review structural and functional manifestations of this cochlear synaptopathy and will consider possible mechanisms underlying its appearance and progression in ears with and without traditional 'hearing loss' arising from several common causes in humans.
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MESH Headings
- Animals
- Auditory Perception
- Auditory Threshold
- Cochlear Nerve/metabolism
- Cochlear Nerve/pathology
- Cochlear Nerve/physiopathology
- Glutamic Acid/metabolism
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/pathology
- Hearing
- Hearing Loss, Noise-Induced/metabolism
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Noise-Induced/psychology
- Hearing Loss, Sensorineural/metabolism
- Hearing Loss, Sensorineural/pathology
- Hearing Loss, Sensorineural/physiopathology
- Hearing Loss, Sensorineural/psychology
- Humans
- Nerve Degeneration
- Noise/adverse effects
- Risk Factors
- Synapses/metabolism
- Synapses/pathology
- Synaptic Transmission
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Affiliation(s)
- M Charles Liberman
- Department of Otology and Laryngology, Harvard Medical School, Boston MA, USA; Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston MA, USA
| | - Sharon G Kujawa
- Department of Otology and Laryngology, Harvard Medical School, Boston MA, USA; Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston MA, USA.
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14
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Vlajkovic SM, Ambepitiya K, Barclay M, Boison D, Housley GD, Thorne PR. Adenosine receptors regulate susceptibility to noise-induced neural injury in the mouse cochlea and hearing loss. Hear Res 2016; 345:43-51. [PMID: 28034618 DOI: 10.1016/j.heares.2016.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/15/2016] [Accepted: 12/20/2016] [Indexed: 12/20/2022]
Abstract
Our previous studies have shown that the stimulation of A1 adenosine receptors in the inner ear can mitigate the loss of sensory hair cells and hearing loss caused by exposure to traumatic noise. Here, we focus on the role of adenosine receptors (AR) in the development of noise-induced neural injury in the cochlea using A1AR and A2AAR null mice (A1AR-/- and A2AAR-/-). Wildtype (WT) and AR deficient mice were exposed to octave band noise (8-16 kHz, 100 dB SPL) for 2 h to induce cochlear injury and hearing loss. Auditory thresholds and input/output functions were assessed using auditory brainstem responses (ABR) before and two weeks post-exposure. The loss of outer hair cells (OHC), afferent synapses and spiral ganglion neurons (SGN) were assessed by quantitative histology. A1AR-/- mice (6-8 weeks old) displayed a high frequency hearing loss (ABR threshold shift and reduced ABR wave I and II amplitudes). This hearing loss was further aggravated by acute noise exposure and exceeded the hearing loss in the WT and A2AAR-/- mice. All mice experienced the loss of OHC, synaptic ribbons and SGN after noise exposure, but the loss of SGN was significantly higher in A1AR-/- mice than in the A2AAR-/- and WT genotypes. The A2AAR-/- demonstrated better preservation of OHC and afferent synapses and the minimal loss of SGN after noise exposure. The findings suggest that the loss of A1AR expression results in an increased susceptibility to cochlear neural injury and hearing loss, whilst absence of A2AAR increases cochlear resistance to acoustic trauma.
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Affiliation(s)
- Srdjan M Vlajkovic
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand.
| | - Kaushi Ambepitiya
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
| | - Meagan Barclay
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
| | - Detlev Boison
- RS Dow Neurobiology Laboratories, Legacy Research, Portland, OR, 97232, USA
| | - Gary D Housley
- Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, UNSW Australia, Sydney, NSW, 2052, Australia
| | - Peter R Thorne
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
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15
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Reijntjes DO, Pyott SJ. The afferent signaling complex: Regulation of type I spiral ganglion neuron responses in the auditory periphery. Hear Res 2016; 336:1-16. [DOI: 10.1016/j.heares.2016.03.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 02/12/2016] [Accepted: 03/07/2016] [Indexed: 12/19/2022]
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16
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Barclay M, Constable R, James NR, Thorne PR, Montgomery JM. Reduced sensory stimulation alters the molecular make-up of glutamatergic hair cell synapses in the developing cochlea. Neuroscience 2016; 325:50-62. [PMID: 27012610 DOI: 10.1016/j.neuroscience.2016.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 02/26/2016] [Accepted: 03/16/2016] [Indexed: 12/20/2022]
Abstract
Neural activity during early development is known to alter innervation pathways in the central and peripheral nervous systems. We sought to examine how reduced sound-induced sensory activity in the cochlea affected the consolidation of glutamatergic synapses between inner hair cells (IHC) and the primary auditory neurons as these synapses play a primary role in transmitting sound information to the brain. A unilateral conductive hearing loss was induced prior to the onset of sound-mediated stimulation of the sensory hair cells, by rupturing the tympanic membrane and dislocating the auditory ossicles in the left ear of P11 mice. Auditory brainstem responses at P15 and P21 showed a 40-50-dB increase in thresholds for frequencies 8-32kHz in the dislocated ear relative to the control ear. Immunohistochemistry and confocal microscopy were subsequently used to examine the effect of this attenuation of sound stimulation on the expression of RIBEYE, which comprises the presynaptic ribbons, Shank-1, a postsynaptic scaffolding protein, and the GluA2/3 and 4 subunits of postsynaptic AMPA receptors. Our results show that dislocation did not alter the number of pre- or postsynaptic protein puncta. However, dislocation did increase the size of RIBEYE, GluA4, GluA2/3 and Shank-1 puncta, with postsynaptic changes preceding presynaptic changes. Our data suggest that a reduction in sound stimulation during auditory development induces plasticity in the molecular make-up of IHC glutamatergic synapses, but does not affect the number of these synapses. Up-regulation of synaptic proteins with sound attenuation may facilitate a compensatory increase in synaptic transmission due to the reduced sensory stimulation of the IHC.
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Affiliation(s)
- M Barclay
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - R Constable
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - N R James
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - P R Thorne
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Section of Audiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - J M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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Kujawa SG, Liberman MC. Synaptopathy in the noise-exposed and aging cochlea: Primary neural degeneration in acquired sensorineural hearing loss. Hear Res 2015; 330:191-9. [PMID: 25769437 PMCID: PMC4567542 DOI: 10.1016/j.heares.2015.02.009] [Citation(s) in RCA: 480] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/26/2015] [Accepted: 02/25/2015] [Indexed: 12/24/2022]
Abstract
The classic view of sensorineural hearing loss (SNHL) is that the "primary" targets are hair cells, and that cochlear-nerve loss is "secondary" to hair cell degeneration. Our recent work in mouse and guinea pig has challenged that view. In noise-induced hearing loss, exposures causing only reversible threshold shifts (and no hair cell loss) nevertheless cause permanent loss of >50% of cochlear-nerve/hair-cell synapses. Similarly, in age-related hearing loss, degeneration of cochlear synapses precedes both hair cell loss and threshold elevation. This primary neural degeneration has remained hidden for three reasons: 1) the spiral ganglion cells, the cochlear neural elements commonly assessed in studies of SNHL, survive for years despite loss of synaptic connection with hair cells, 2) the synaptic terminals of cochlear nerve fibers are unmyelinated and difficult to see in the light microscope, and 3) the degeneration is selective for cochlear-nerve fibers with high thresholds. Although not required for threshold detection in quiet (e.g. threshold audiometry or auditory brainstem response threshold), these high-threshold fibers are critical for hearing in noisy environments. Our research suggests that 1) primary neural degeneration is an important contributor to the perceptual handicap in SNHL, and 2) in cases where the hair cells survive, neurotrophin therapies can elicit neurite outgrowth from spiral ganglion neurons and re-establishment of their peripheral synapses. This article is part of a Special Issue entitled .
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Affiliation(s)
- Sharon G Kujawa
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA; Eaton-Peabody Laboratory, Massachusetts Eye & Ear Infirmary, Boston, MA, USA; Department of Audiology, Massachusetts Eye and Ear, Boston, MA, USA
| | - M Charles Liberman
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA; Eaton-Peabody Laboratory, Massachusetts Eye & Ear Infirmary, Boston, MA, USA.
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18
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Cochlear afferent innervation development. Hear Res 2015; 330:157-69. [DOI: 10.1016/j.heares.2015.07.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 06/02/2015] [Accepted: 07/21/2015] [Indexed: 01/11/2023]
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19
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Knipper M, Panford-Walsh R, Singer W, Rüttiger L, Zimmermann U. Specific synaptopathies diversify brain responses and hearing disorders: you lose the gain from early life. Cell Tissue Res 2015; 361:77-93. [PMID: 25843689 PMCID: PMC4487345 DOI: 10.1007/s00441-015-2168-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/05/2015] [Indexed: 01/08/2023]
Abstract
Before hearing onset, inner hair cell (IHC) maturation proceeds under the influence of spontaneous Ca(2+) action potentials (APs). The temporal signature of the IHC Ca(2+) AP is modified through an efferent cholinergic feedback from the medial olivocochlear bundle (MOC) and drives the IHC pre- and post-synapse phenotype towards low spontaneous (spike) rate (SR), high-threshold characteristics. With sensory experience, the IHC pre- and post-synapse phenotype matures towards the instruction of low-SR, high-threshold and of high-SR, low-threshold auditory fiber characteristics. Corticosteroid feedback together with local brain-derived nerve growth factor (BDNF) and catecholaminergic neurotransmitters (dopamine) might be essential for this developmental step. In this review, we address the question of whether the control of low-SR and high-SR fiber characteristics is linked to various degrees of vulnerability of auditory fibers in the mature system. In particular, we examine several IHC synaptopathies in the context of various hearing disorders and exemplified shortfalls before and after hearing onset.
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Affiliation(s)
- Marlies Knipper
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | | | - Wibke Singer
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | - Ulrike Zimmermann
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
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20
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Wan G, Corfas G. No longer falling on deaf ears: mechanisms of degeneration and regeneration of cochlear ribbon synapses. Hear Res 2015; 329:1-10. [PMID: 25937135 DOI: 10.1016/j.heares.2015.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 04/01/2015] [Accepted: 04/20/2015] [Indexed: 01/02/2023]
Abstract
Cochlear ribbon synapses are required for the rapid and precise neural transmission of acoustic signals from inner hair cells to the spiral ganglion neurons. Emerging evidence suggests that damage to these synapses represents an important form of cochlear neuropathy that might be highly prevalent in sensorineural hearing loss. In this review, we discuss our current knowledge on how ribbon synapses are damaged by noise and during aging, as well as potential strategies to promote ribbon synapse regeneration for hearing restoration.
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Affiliation(s)
- Guoqiang Wan
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gabriel Corfas
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
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21
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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22
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Wan G, Gómez-Casati ME, Gigliello AR, Liberman MC, Corfas G. Neurotrophin-3 regulates ribbon synapse density in the cochlea and induces synapse regeneration after acoustic trauma. eLife 2014; 3. [PMID: 25329343 PMCID: PMC4227045 DOI: 10.7554/elife.03564] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 10/09/2014] [Indexed: 12/23/2022] Open
Abstract
Neurotrophin-3 (Ntf3) and brain derived neurotrophic factor (Bdnf) are critical for sensory neuron survival and establishment of neuronal projections to sensory epithelia in the embryonic inner ear, but their postnatal functions remain poorly understood. Using cell-specific inducible gene recombination in mice we found that, in the postnatal inner ear, Bbnf and Ntf3 are required for the formation and maintenance of hair cell ribbon synapses in the vestibular and cochlear epithelia, respectively. We also show that supporting cells in these epithelia are the key endogenous source of the neurotrophins. Using a new hair cell CreER(T) line with mosaic expression, we also found that Ntf3's effect on cochlear synaptogenesis is highly localized. Moreover, supporting cell-derived Ntf3, but not Bbnf, promoted recovery of cochlear function and ribbon synapse regeneration after acoustic trauma. These results indicate that glial-derived neurotrophins play critical roles in inner ear synapse density and synaptic regeneration after injury.
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Affiliation(s)
- Guoqiang Wan
- F M Kirby Neurobiology Center, Boston Children's Hospital, Boston, United States
| | - Maria E Gómez-Casati
- F M Kirby Neurobiology Center, Boston Children's Hospital, Boston, United States
| | - Angelica R Gigliello
- F M Kirby Neurobiology Center, Boston Children's Hospital, Boston, United States
| | - M Charles Liberman
- Department of Otology and Laryngology, Harvard Medical School, Boston, United States
| | - Gabriel Corfas
- F M Kirby Neurobiology Center, Boston Children's Hospital, Boston, United States
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23
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Gómez-Nieto R, Horta-Júnior JDAC, Castellano O, Millian-Morell L, Rubio ME, López DE. Origin and function of short-latency inputs to the neural substrates underlying the acoustic startle reflex. Front Neurosci 2014; 8:216. [PMID: 25120419 PMCID: PMC4110630 DOI: 10.3389/fnins.2014.00216] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 07/03/2014] [Indexed: 11/13/2022] Open
Abstract
The acoustic startle reflex (ASR) is a survival mechanism of alarm, which rapidly alerts the organism to a sudden loud auditory stimulus. In rats, the primary ASR circuit encompasses three serially connected structures: cochlear root neurons (CRNs), neurons in the caudal pontine reticular nucleus (PnC), and motoneurons in the medulla and spinal cord. It is well-established that both CRNs and PnC neurons receive short-latency auditory inputs to mediate the ASR. Here, we investigated the anatomical origin and functional role of these inputs using a multidisciplinary approach that combines morphological, electrophysiological and behavioral techniques. Anterograde tracer injections into the cochlea suggest that CRNs somata and dendrites receive inputs depending, respectively, on their basal or apical cochlear origin. Confocal colocalization experiments demonstrated that these cochlear inputs are immunopositive for the vesicular glutamate transporter 1 (VGLUT1). Using extracellular recordings in vivo followed by subsequent tracer injections, we investigated the response of PnC neurons after contra-, ipsi-, and bilateral acoustic stimulation and identified the source of their auditory afferents. Our results showed that the binaural firing rate of PnC neurons was higher than the monaural, exhibiting higher spike discharges with contralateral than ipsilateral acoustic stimulations. Our histological analysis confirmed the CRNs as the principal source of short-latency acoustic inputs, and indicated that other areas of the cochlear nucleus complex are not likely to innervate PnC. Behaviorally, we observed a strong reduction of ASR amplitude in monaural earplugged rats that corresponds with the binaural summation process shown in our electrophysiological findings. Our study contributes to understand better the role of neuronal mechanisms in auditory alerting behaviors and provides strong evidence that the CRNs-PnC pathway mediates fast neurotransmission and binaural summation of the ASR.
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Affiliation(s)
- Ricardo Gómez-Nieto
- Neuroscience Institute of Castilla y León, University of Salamanca Salamanca, Spain ; Department of Cell Biology and Pathology, University of Salamanca Salamanca, Spain ; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca Salamanca, Spain
| | - José de Anchieta C Horta-Júnior
- Neuroscience Institute of Castilla y León, University of Salamanca Salamanca, Spain ; Department of Anatomy, Biosciences Institute, São Paulo State University Botucatu São Paulo, Brazil
| | - Orlando Castellano
- Neuroscience Institute of Castilla y León, University of Salamanca Salamanca, Spain ; Department of Cell Biology and Pathology, University of Salamanca Salamanca, Spain ; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca Salamanca, Spain
| | - Lymarie Millian-Morell
- Neuroscience Institute of Castilla y León, University of Salamanca Salamanca, Spain ; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca Salamanca, Spain
| | - Maria E Rubio
- Department of Otolaryngology, University of Pittsburgh Pittsburgh, PA, USA
| | - Dolores E López
- Neuroscience Institute of Castilla y León, University of Salamanca Salamanca, Spain ; Department of Cell Biology and Pathology, University of Salamanca Salamanca, Spain ; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca Salamanca, Spain
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24
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Morphological and physiological development of auditory synapses. Hear Res 2014; 311:3-16. [PMID: 24508369 DOI: 10.1016/j.heares.2014.01.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 01/13/2014] [Accepted: 01/20/2014] [Indexed: 02/07/2023]
Abstract
Acoustic communication requires gathering, transforming, and interpreting diverse sound cues. To achieve this, all the spatial and temporal features of complex sound stimuli must be captured in the firing patterns of the primary sensory neurons and then accurately transmitted along auditory pathways for additional processing. The mammalian auditory system relies on several synapses with unique properties in order to meet this task: the auditory ribbon synapses, the endbulb of Held, and the calyx of Held. Each of these synapses develops morphological and electrophysiological characteristics that enable the remarkably precise signal transmission necessary for conveying the miniscule differences in timing that underly sound localization. In this article, we review the current knowledge of how these synapses develop and mature to acquire the specialized features necessary for the sense of hearing.
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Bas E, Van De Water TR, Lumbreras V, Rajguru S, Goss G, Hare JM, Goldstein BJ. Adult human nasal mesenchymal-like stem cells restore cochlear spiral ganglion neurons after experimental lesion. Stem Cells Dev 2013; 23:502-14. [PMID: 24172073 DOI: 10.1089/scd.2013.0274] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A loss of sensory hair cells or spiral ganglion neurons from the inner ear causes deafness, affecting millions of people. Currently, there is no effective therapy to repair the inner ear sensory structures in humans. Cochlear implantation can restore input, but only if auditory neurons remain intact. Efforts to develop stem cell-based treatments for deafness have demonstrated progress, most notably utilizing embryonic-derived cells. In an effort to bypass limitations of embryonic or induced pluripotent stem cells that may impede the translation to clinical applications, we sought to utilize an alternative cell source. Here, we show that adult human mesenchymal-like stem cells (MSCs) obtained from nasal tissue can repair spiral ganglion loss in experimentally lesioned cochlear cultures from neonatal rats. Stem cells engraft into gentamicin-lesioned organotypic cultures and orchestrate the restoration of the spiral ganglion neuronal population, involving both direct neuronal differentiation and secondary effects on endogenous cells. As a physiologic assay, nasal MSC-derived cells engrafted into lesioned spiral ganglia demonstrate responses to infrared laser stimulus that are consistent with those typical of excitable cells. The addition of a pharmacologic activator of the canonical Wnt/β-catenin pathway concurrent with stem cell treatment promoted robust neuronal differentiation. The availability of an effective adult autologous cell source for inner ear tissue repair should contribute to efforts to translate cell-based strategies to the clinic.
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Affiliation(s)
- Esperanza Bas
- 1 Department of Otolaryngology, University of Miami Miller School of Medicine , Miami, Florida
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26
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Peng Z, Wang GP, Zeng R, Guo JY, Chen CF, Gong SS. Temporospatial expression and cellular localization of VGLUT3 in the rat cochlea. Brain Res 2013; 1537:100-10. [DOI: 10.1016/j.brainres.2013.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 09/11/2013] [Accepted: 09/17/2013] [Indexed: 01/06/2023]
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Ahmed S, Vorasubin N, Lopez IA, Hosokawa S, Ishiyama G, Ishiyama A. The expression of glutamate aspartate transporter (GLAST) within the human cochlea and its distribution in various patient populations. Brain Res 2013; 1529:134-42. [PMID: 23850643 DOI: 10.1016/j.brainres.2013.06.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/14/2013] [Accepted: 06/26/2013] [Indexed: 10/26/2022]
Abstract
Glutamate plays an important role in the central nervous system as an excitatory neurotransmitter. However, its abundance can lead to excitotoxicity which necessitates the proper function of active glutamate transporters. The glutamate-aspartate transporter (GLAST) has been shown to exist and function within non-human cochlear specimens regulating the inner ear glutamate concentration. In this study, we examined human cochleas from formalin-fixed celloidin-embedded temporal bone specimens of three different types of patients (Meniere's disease, normal controls, and other otopathologic conditions) and examined the differential expression of GLAST in the spiral ligament of the basal, middle, and apical turns of the cochlea. Immunohistochemical staining was performed with polyclonal antibodies against GLAST and image analysis was carried out with the Image J analysis software. In contrast to other studies with non-human specimens, GLAST was expressed in the spiral ligament fibrocytes but was not detected in the satellite cells of the spiral ganglia or supporting cells of the Organ of Corti in the human cochlea. Our data also showed that GLAST expression significantly differs in the basal and apical turns of the cochlea. Lastly, post-hoc analysis showed a difference in the GLAST immunoreactive area of patients with Meniere's disease when compared to that of patients with other otopathologic conditions-such as presbycusis or ototoxicity. These results may potentially lead to further understanding of different disease states that affect hearing.
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Affiliation(s)
- Sameer Ahmed
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1624, USA
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28
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Coate TM, Kelley MW. Making connections in the inner ear: recent insights into the development of spiral ganglion neurons and their connectivity with sensory hair cells. Semin Cell Dev Biol 2013; 24:460-9. [PMID: 23660234 PMCID: PMC3690159 DOI: 10.1016/j.semcdb.2013.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 04/15/2013] [Indexed: 01/18/2023]
Abstract
In mammals, auditory information is processed by the hair cells (HCs) located in the cochlea and then rapidly transmitted to the CNS via a specialized cluster of bipolar afferent connections known as the spiral ganglion neurons (SGNs). Although many anatomical aspects of SGNs are well described, the molecular and cellular mechanisms underlying their genesis, how they are precisely arranged along the cochlear duct, and the guidance mechanisms that promote the innervation of their hair cell targets are only now being understood. Building upon foundational studies of neurogenesis and neurotrophins, we review here new concepts and technologies that are helping to enrich our understanding of the development of the nervous system within the inner ear.
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Affiliation(s)
- Thomas M Coate
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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29
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Furman AC, Kujawa SG, Liberman MC. Noise-induced cochlear neuropathy is selective for fibers with low spontaneous rates. J Neurophysiol 2013; 110:577-86. [PMID: 23596328 DOI: 10.1152/jn.00164.2013] [Citation(s) in RCA: 526] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acoustic overexposure can cause a permanent loss of auditory nerve fibers without destroying cochlear sensory cells, despite complete recovery of cochlear thresholds (Kujawa and Liberman 2009), as measured by gross neural potentials such as the auditory brainstem response (ABR). To address this nominal paradox, we recorded responses from single auditory nerve fibers in guinea pigs exposed to this type of neuropathic noise (4- to 8-kHz octave band at 106 dB SPL for 2 h). Two weeks postexposure, ABR thresholds had recovered to normal, while suprathreshold ABR amplitudes were reduced. Both thresholds and amplitudes of distortion-product otoacoustic emissions fully recovered, suggesting recovery of hair cell function. Loss of up to 30% of auditory-nerve synapses on inner hair cells was confirmed by confocal analysis of the cochlear sensory epithelium immunostained for pre- and postsynaptic markers. In single fiber recordings, at 2 wk postexposure, frequency tuning, dynamic range, postonset adaptation, first-spike latency and its variance, and other basic properties of auditory nerve response were all completely normal in the remaining fibers. The only physiological abnormality was a change in population statistics suggesting a selective loss of fibers with low- and medium-spontaneous rates. Selective loss of these high-threshold fibers would explain how ABR thresholds can recover despite such significant noise-induced neuropathy. A selective loss of high-threshold fibers may contribute to the problems of hearing in noisy environments that characterize the aging auditory system.
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Affiliation(s)
- Adam C Furman
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
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30
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Monzack EL, Cunningham LL. Lead roles for supporting actors: critical functions of inner ear supporting cells. Hear Res 2013; 303:20-9. [PMID: 23347917 DOI: 10.1016/j.heares.2013.01.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/20/2012] [Accepted: 01/10/2013] [Indexed: 12/27/2022]
Abstract
Many studies that aim to investigate the underlying mechanisms of hearing loss or balance disorders focus on the hair cells and spiral ganglion neurons of the inner ear. Fewer studies have examined the supporting cells that contact both of these cell types in the cochlea and vestibular end organs. While the roles of supporting cells are still being elucidated, emerging evidence indicates that they serve many functions vital to maintaining healthy populations of hair cells and spiral ganglion neurons. Here we review recent studies that highlight the critical roles supporting cells play in the development, function, survival, death, phagocytosis, and regeneration of other cell types within the inner ear. Many of these roles have also been described for glial cells in other parts of the nervous system, and lessons from these other systems continue to inform our understanding of supporting cell functions. This article is part of a Special Issue entitled "Annual Reviews 2013".
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Affiliation(s)
- Elyssa L Monzack
- National Institute on Deafness and Other Communication Disorders, 5 Research Court, Rockville, MD 20850, USA.
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31
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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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32
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Schraven SP, Franz C, Rüttiger L, Löwenheim H, Lysakowski A, Stoffel W, Knipper M. Altered phenotype of the vestibular organ in GLAST-1 null mice. J Assoc Res Otolaryngol 2012; 13:323-33. [PMID: 22350511 DOI: 10.1007/s10162-011-0311-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 12/21/2011] [Indexed: 01/11/2023] Open
Abstract
Various studies point to a crucial role of the high-affinity sodium-coupled glutamate aspartate transporter GLAST-1 for modulation of excitatory transmission as shown in the retina and the CNS. While 2-4-month-old GLAST-1 null mice did not show any functional vestibular abnormality, we observed profound circling behavior in older (7 months) animals lacking GLAST-1. An unchanged total number of otoferlin-positive vestibular hair cells (VHCs), similar ribbon numbers in VHCs, and an unchanged VGLUT3 expression in type II VHCs were detected in GLAST-1 null compared to wild-type mice. A partial loss of supporting cells and an apparent decline of a voltage-gated channel potassium subunit (KCNQ4) was observed in postsynaptic calyceal afferents contacting type I VHCs, together with a reduction of neurofilament- (NF200-) and vesicular glutamate transporter 1- (VGLUT1-) positive calyces in GLAST-1 null mice. Taken together, GLAST-1 deletion appeared to preferentially affect the maintenance of a normal postsynaptic/neuronal phenotype, evident only with increasing age.
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Affiliation(s)
- Sebastian P Schraven
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Str. 5, 72076 Tübingen, Germany
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33
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Taylor RR, Jagger DJ, Forge A. Defining the cellular environment in the organ of Corti following extensive hair cell loss: a basis for future sensory cell replacement in the Cochlea. PLoS One 2012; 7:e30577. [PMID: 22299045 PMCID: PMC3267727 DOI: 10.1371/journal.pone.0030577] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 12/21/2011] [Indexed: 01/01/2023] Open
Abstract
Background Following the loss of hair cells from the mammalian cochlea, the sensory epithelium repairs to close the lesions but no new hair cells arise and hearing impairment ensues. For any cell replacement strategy to be successful, the cellular environment of the injured tissue has to be able to nurture new hair cells. This study defines characteristics of the auditory sensory epithelium after hair cell loss. Methodology/Principal Findings Studies were conducted in C57BL/6 and CBA/Ca mice. Treatment with an aminoglycoside-diuretic combination produced loss of all outer hair cells within 48 hours in both strains. The subsequent progressive tissue re-organisation was examined using immunohistochemistry and electron microscopy. There was no evidence of significant de-differentiation of the specialised columnar supporting cells. Kir4.1 was down regulated but KCC4, GLAST, microtubule bundles, connexin expression patterns and pathways of intercellular communication were retained. The columnar supporting cells became covered with non-specialised cells migrating from the outermost region of the organ of Corti. Eventually non-specialised, flat cells replaced the columnar epithelium. Flat epithelium developed in distributed patches interrupting regions of columnar epithelium formed of differentiated supporting cells. Formation of the flat epithelium was initiated within a few weeks post-treatment in C57BL/6 mice but not for several months in CBA/Ca's, suggesting genetic background influences the rate of re-organisation. Conclusions/Significance The lack of dedifferentiation amongst supporting cells and their replacement by cells from the outer side of the organ of Corti are factors that may need to be considered in any attempt to promote endogenous hair cell regeneration. The variability of the cellular environment along an individual cochlea arising from patch-like generation of flat epithelium, and the possible variability between individuals resulting from genetic influences on the rate at which remodelling occurs may pose challenges to devising the appropriate regenerative therapy for a deaf patient.
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Affiliation(s)
- Ruth R Taylor
- Centre for Auditory Research, The Ear Institute, University College London, London, United Kingdom.
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34
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Defourny J, Lallemend F, Malgrange B. Structure and development of cochlear afferent innervation in mammals. Am J Physiol Cell Physiol 2011; 301:C750-61. [PMID: 21753183 DOI: 10.1152/ajpcell.00516.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In mammals, sensorineural deafness results from damage to the auditory receptors of the inner ear, the nerve pathways to the brain or the cortical area that receives sound information. In this review, we first focused on the cellular and molecular events taking part to spiral ganglion axon growth, extension to the organ of Corti, and refinement. In the second half, we considered the functional maturation of synaptic contacts between sensory hair cells and their afferent projections. A better understanding of all these processes could open insights into novel therapeutic strategies aimed to re-establish primary connections from sound transducers to the ascending auditory nerve pathways.
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35
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Zhang F, Pang Y, Zhang M, Zhang T, Dong Y, Lai C, Shum D, Chan Y, Li J, Li Y. Expression of vesicular glutamate transporters in peripheral vestibular structures and vestibular nuclear complex of rat. Neuroscience 2011; 173:179-89. [DOI: 10.1016/j.neuroscience.2010.11.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 11/08/2010] [Accepted: 11/09/2010] [Indexed: 11/17/2022]
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36
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Chen Z, Kujawa SG, Sewell WF. Functional roles of high-affinity glutamate transporters in cochlear afferent synaptic transmission in the mouse. J Neurophysiol 2010; 103:2581-6. [PMID: 20220082 DOI: 10.1152/jn.00018.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the cochlea, afferent transmission between inner hair cells and auditory neurons is mediated by glutamate receptors. Glutamate transporters located near the synapse and in spiral ganglion neurons are thought to maintain low synaptic levels of glutamate. We analyzed three glutamate transporter blockers for their ability to alter the effects of glutamate, exogenously applied to the synapse via perfusion of the scala tympani of the mouse, and compared that action to their ability to alter the effects of intense acoustic stimulation. Threo-beta-benzyloxyaspartate (TBOA) is a broad-spectrum glutamate transporter antagonist, affecting all three transporters [glutamate/aspartate transporter (GLAST), glutamate transporter-1 (GLT1), and excitatory amino acid carrier 1 (EAAC1)]. l-serine-O-sulfate (SOS) blocks both GLAST and EAAC1 without effect on GLT1. Dihydrokainate (DHK) is selective for GLT1. Infusion of glutamate (10 microM for 220 min), TBOA (200 microM for 220 min), or SOS (100 microM for 180 min) alone did not alter auditory neural thresholds. When infused together with glutamate, TBOA and SOS produced significant neural threshold shifts, leaving otoacoustic emissions intact. In addition, both TBOA and SOS exacerbated noise-induced hearing loss by producing larger neural threshold shifts and delaying recovery. DHK did not alter glutamate- or noise-induced hearing loss. The evidence points to a major role for GLAST, both in protecting the synapse from exposure to excess extracellular glutamate and in attenuating hearing loss due to acoustic overstimulation.
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Affiliation(s)
- Zhiqiang Chen
- Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston MA 02114, USA
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Delta/notch-like EGF-related receptor (DNER) is expressed in hair cells and neurons in the developing and adult mouse inner ear. J Assoc Res Otolaryngol 2010; 11:187-201. [PMID: 20058045 DOI: 10.1007/s10162-009-0203-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 12/01/2009] [Indexed: 10/20/2022] Open
Abstract
The Notch signaling pathway is known to play important roles in inner ear development. Previous studies have shown that the Notch1 receptor and ligands in the Delta and Jagged families are important for cellular differentiation and patterning of the organ of Corti. Delta/notch-like epidermal growth factor (EGF)-related receptor (DNER) is a novel Notch ligand expressed in developing and adult CNS neurons known to promote maturation of glia through activation of Notch. Here we use in situ hybridization and an antibody against DNER to carry out expression studies of the mouse cochlea and vestibule. We find that DNER is expressed in spiral ganglion neuron cell bodies and peripheral processes during embryonic development of the cochlea and expression in these cells is maintained in adults. DNER becomes strongly expressed in auditory hair cells during postnatal maturation in the mouse cochlea and immunoreactivity for this protein is strong in hair cells and afferent and efferent peripheral nerve endings in the adult organ of Corti. In the vestibular system, we find that DNER is expressed in hair cells and vestibular ganglion neurons during development and in adults. To investigate whether DNER plays a functional role in the inner ear, perhaps similar to its described role in glial maturation, we examined cochleae of DNER-/- mice using immunohistochemical markers of mature glia and supporting cells as well as neurons and hair cells. We found no defects in expression of markers of supporting cells and glia or myelin, and no abnormalities in hair cells or neurons, suggesting that DNER plays a redundant role with other Notch ligands in cochlear development.
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38
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Chen Z, Peppi M, Kujawa SG, Sewell WF. Regulated expression of surface AMPA receptors reduces excitotoxicity in auditory neurons. J Neurophysiol 2009; 102:1152-9. [PMID: 19515954 DOI: 10.1152/jn.00288.2009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dynamic regulation of the expression of surface AMPA receptors (AMPARs) is a key mechanism to modulate synaptic strength and efficacy in the CNS and also to regulate auditory sensitivity. Here we address the role of surface AMPAR expression in excitotoxicity by blocking clathrin-mediated AMPAR endocytosis in auditory neurons. We used a membrane-permeable, dynamin-derived, myristoylated peptide (myr-Dyn) to inhibit surface AMPAR endocytosis induced by glutamate receptor agonists in culture and by noise exposure in vivo. Myr-Dyn infused into the mouse cochlea induced excitotoxic responses to acoustic stimuli that were normally not excitotoxic. These included vacuolization in the nerve terminals and spiral ganglion as well as irreversible auditory brain stem response threshold shifts. In cultured spiral ganglion neuronal cells, blockade of the reduction of surface AMPARs exacerbated neuronal death by incubation with N-methyl-d-aspartate and AMPA. This excitotoxic neuronal death could be prevented by calpeptin, a calpain-specific inhibitor. These results suggest that the reduction of surface AMPAR by endocytosis during excitatory stimulation plays an important role in limiting the excitotoxic damage to the neuron.
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Affiliation(s)
- Zhiqiang Chen
- Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, USA
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39
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Furness DN, Lawton DM, Mahendrasingam S, Hodierne L, Jagger DJ. Quantitative analysis of the expression of the glutamate-aspartate transporter and identification of functional glutamate uptake reveal a role for cochlear fibrocytes in glutamate homeostasis. Neuroscience 2009; 162:1307-21. [PMID: 19464351 DOI: 10.1016/j.neuroscience.2009.05.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 04/29/2009] [Accepted: 05/18/2009] [Indexed: 11/16/2022]
Abstract
There are several subtypes of fibrocyte in the spiral ligament and spiral limbus of the cochlea that may contribute to fluid homeostasis. Immunocytochemical data suggest that these fibrocytes possess the glutamate-aspartate transporter, GLAST, as do supporting cells around the hair cells. However, functional glutamate uptake has not been demonstrated in fibrocytes. We used confocal and post-embedding immunogold electron microscopy to confirm that GLAST is expressed in adult fibrocytes of CD-1 mice with a relative expression: spiral limbus fibrocytes>type II>V>IV>I spiral ligament fibrocytes. Because they were sparsely present in most samples, type III fibrocytes were assessed only in one sample where their GLAST levels were similar to type I. Type II, type V and spiral limbus fibrocytes have many fine cellular processes that increase their surface area, those of the latter two coming into direct contact with perilymph, and type V fibrocytes contain the most glutamate. These data imply that glutamate uptake occurs in the fibrocytes. We assessed uptake of D-aspartate (a glutamate analogue) together with GLAST expression immunocytochemically and electrophysiologically. D-aspartate accumulated into GLAST expressing fibrocytes in vitro and evoked currents blockable by the GLAST inhibitor D,L-threo-beta-benzyloxyaspartate (TBOA), similar to those of supporting cells around inner hair cells. Currents were strongest in spiral limbus fibrocytes, progressively lower in type V and type II fibrocytes, and were negligible in type I fibrocytes in accordance with the relative expression levels of GLAST. We conclude that in addition to their known homeostatic functions, fibrocytes, in particular spiral limbus, type II and type V fibrocytes play a role in glutamate homeostasis in the cochlea.
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Affiliation(s)
- D N Furness
- Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire ST5 5BG, UK.
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40
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Zanazzi G, Matthews G. The molecular architecture of ribbon presynaptic terminals. Mol Neurobiol 2009; 39:130-48. [PMID: 19253034 PMCID: PMC2701268 DOI: 10.1007/s12035-009-8058-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 02/04/2009] [Indexed: 12/24/2022]
Abstract
The primary receptor neurons of the auditory, vestibular, and visual systems encode a broad range of sensory information by modulating the tonic release of the neurotransmitter glutamate in response to graded changes in membrane potential. The output synapses of these neurons are marked by structures called synaptic ribbons, which tether a pool of releasable synaptic vesicles at the active zone where glutamate release occurs in response to calcium influx through L-type channels. Ribbons are composed primarily of the protein, RIBEYE, which is unique to ribbon synapses, but cytomatrix proteins that regulate the vesicle cycle in conventional terminals, such as Piccolo and Bassoon, also are found at ribbons. Conventional and ribbon terminals differ, however, in the size, molecular composition, and mobilization of their synaptic vesicle pools. Calcium-binding proteins and plasma membrane calcium pumps, together with endomembrane pumps and channels, play important roles in calcium handling at ribbon synapses. Taken together, emerging evidence suggests that several molecular and cellular specializations work in concert to support the sustained exocytosis of glutamate that is a hallmark of ribbon synapses. Consistent with its functional importance, abnormalities in a variety of functional aspects of the ribbon presynaptic terminal underlie several forms of auditory neuropathy and retinopathy.
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Affiliation(s)
- George Zanazzi
- Department of Neurobiology & Behavior, State Universtiy of New York, Stony Brook, NY 11794-5230, USA
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McLean WJ, Smith KA, Glowatzki E, Pyott SJ. Distribution of the Na,K-ATPase alpha subunit in the rat spiral ganglion and organ of corti. J Assoc Res Otolaryngol 2008; 10:37-49. [PMID: 19082858 DOI: 10.1007/s10162-008-0152-9] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Accepted: 11/20/2008] [Indexed: 12/29/2022] Open
Abstract
Processing of sound in the cochlea involves both afferent and efferent innervation. The Na,K-ATPase (NKA) is essential for cells that maintain hyperpolarized membrane potentials and sodium and potassium concentration gradients. Heterogeneity of NKA subunit expression is one mechanism that tailors physiology to particular cellular demands. Therefore, to provide insight into molecular differences that distinguish the various innervation pathways in the cochlea, we performed a variety of double labeling experiments with antibodies against three of the alpha isoforms of the NKA (NKA alpha 1-3) and markers identifying particular subsets of neurons or supporting cells in whole mount preparations of the organ of Corti and spiral ganglion. We found that the NKA alpha 3 is abundantly expressed within the membranes of the spiral ganglion somata, the type I afferent terminals contacting the inner hair cells, and the medial efferent terminals contacting the outer hair cells. We also found expression of the NKA alpha 1 in the supporting cells that neighbor the inner hair cells and express the glutamate transporter GLAST. These findings suggest that both the NKA alpha 1 and NKA alpha 3 are poised to play an essential role in the regulation of the type I afferent synapses, the medial efferent synapses, and also glutamate transport from the afferent-inner hair cell synapse.
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Affiliation(s)
- Will J McLean
- Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA
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Glowatzki E, Grant L, Fuchs P. Hair cell afferent synapses. Curr Opin Neurobiol 2008; 18:389-95. [PMID: 18824101 DOI: 10.1016/j.conb.2008.09.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 09/08/2008] [Accepted: 09/15/2008] [Indexed: 12/30/2022]
Abstract
This review will cover advances in the study of hair cell afferent synaptic function occurring between 2005 and 2008. During this time, capacitance measurements of vesicular fusion have continued to be refined, optical methods have added insights regarding vesicle trafficking, and paired intracellular recordings have established the transfer function of the afferent synapse at high resolution. Further, genes have been identified with forms of deafness known as auditory neuropathy, and their role in afferent signaling explored in mouse models. With these advances, our view of the hair cell afferent synapse has continued to be refined, and surprising properties have been revealed that emphasize the unique role of this structure in neural function.
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Affiliation(s)
- Elisabeth Glowatzki
- Department of Otolaryngology, Johns Hopkins School of Medicine, 720 Rutland Avenue, Ross 824, Baltimore, MD 21205, United States.
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Spiwoks-Becker I, Maus C, tom Dieck S, Fejtová A, Engel L, Wolloscheck T, Wolfrum U, Vollrath L, Spessert R. Active zone proteins are dynamically associated with synaptic ribbons in rat pinealocytes. Cell Tissue Res 2008; 333:185-95. [PMID: 18523806 PMCID: PMC2757586 DOI: 10.1007/s00441-008-0627-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Accepted: 04/18/2008] [Indexed: 11/30/2022]
Abstract
Synaptic ribbons (SRs) are prominent organelles that are abundant in the ribbon synapses of sensory neurons where they represent a specialization of the cytomatrix at the active zone (CAZ). SRs occur not only in neurons, but also in neuroendocrine pinealocytes where their function is still obscure. In this study, we report that pinealocyte SRs are associated with CAZ proteins such as Bassoon, Piccolo, CtBP1, Munc13–1, and the motorprotein KIF3A and, therefore, consist of a protein complex that resembles the ribbon complex of retinal and other sensory ribbon synapses. The pinealocyte ribbon complex is biochemically dynamic. Its protein composition changes in favor of Bassoon, Piccolo, and Munc13–1 at night and in favor of KIF3A during the day, whereas CtBP1 is equally present during the night and day. The diurnal dynamics of the ribbon complex persist under constant darkness and decrease after stimulus deprivation of the pineal gland by constant light. Our findings indicate that neuroendocrine pinealocytes possess a protein complex that resembles the CAZ of ribbon synapses in sensory organs and whose dynamics are under circadian regulation.
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Affiliation(s)
- Isabella Spiwoks-Becker
- Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, Mainz, Germany.
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Halmos G, Horváth T, Polony G, Fekete Á, Kittel A, Vizi E, van der Laan B, Zelles T, Lendvai B. The role of N-methyl-d-aspartate receptors and nitric oxide in cochlear dopamine release. Neuroscience 2008; 154:796-803. [DOI: 10.1016/j.neuroscience.2008.03.071] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 03/27/2008] [Accepted: 03/27/2008] [Indexed: 11/26/2022]
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Seal RP, Akil O, Yi E, Weber CM, Grant L, Yoo J, Clause A, Kandler K, Noebels JL, Glowatzki E, Lustig LR, Edwards RH. Sensorineural deafness and seizures in mice lacking vesicular glutamate transporter 3. Neuron 2008; 57:263-75. [PMID: 18215623 DOI: 10.1016/j.neuron.2007.11.032] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 10/26/2007] [Accepted: 11/19/2007] [Indexed: 12/22/2022]
Abstract
The expression of unconventional vesicular glutamate transporter VGLUT3 by neurons known to release a different classical transmitter has suggested novel roles for signaling by glutamate, but this distribution has raised questions about whether the protein actually contributes to glutamate release. We now report that mice lacking VGLUT3 are profoundly deaf due to the absence of glutamate release from hair cells at the first synapse in the auditory pathway. The early degeneration of some cochlear ganglion neurons in knockout mice also indicates an important developmental role for the glutamate released by hair cells before the onset of hearing. In addition, the mice exhibit primary, generalized epilepsy that is accompanied by remarkably little change in ongoing motor behavior. The glutamate release conferred by expression of VGLUT3 thus has an essential role in both function and development of the auditory pathway, as well as in the control of cortical excitability.
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Affiliation(s)
- Rebecca P Seal
- Department of Physiology, School of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
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Gómez-Nieto R, Horta-Junior JAC, Castellano O, Herrero-Turrión MJ, Rubio ME, López DE. Neurochemistry of the afferents to the rat cochlear root nucleus: possible synaptic modulation of the acoustic startle. Neuroscience 2008; 154:51-64. [PMID: 18384963 DOI: 10.1016/j.neuroscience.2008.01.079] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 01/30/2008] [Accepted: 01/31/2008] [Indexed: 10/22/2022]
Abstract
Afferents to the primary startle circuit are essential for the elicitation and modulation of the acoustic startle reflex (ASR). In the rat, cochlear root neurons (CRNs) comprise the first component of the acoustic startle circuit and play a crucial role in mediating the ASR. Nevertheless, the neurochemical pattern of their afferents remains unclear. To determine the distribution of excitatory and inhibitory inputs, we used confocal microscopy to analyze the immunostaining for vesicular glutamate and GABA transporter proteins (VGLUT1 and VGAT) on retrogradely labeled CRNs. We also used reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry to detect and localize specific neurotransmitter receptor subunits in the cochlear root. Our results show differential distributions of VGLUT1- and VGAT-immunoreactive endings around cell bodies and dendrites. The RT-PCR data showed a positive band for several ionotropic glutamate receptor subunits, M1-M5 muscarinic receptor subtypes, the glycine receptor alpha1 subunit (GlyRalpha1), GABAA, GABAB, and subunits of alpha2 and beta-noradrenergic receptors. By immunohistochemistry, we confirmed that CRN cell bodies exhibit positive immunoreaction for the glutamate receptor (GluR) 3 and NR1 GluR subunits. Cell bodies and dendrites were also positive for M2 and M4, and GlyRalpha1. Other subunits, such as GluR1 and GluR4 of the AMPA GluRs, were observed in glial cells neighboring unlabeled CRN cell bodies. We further confirmed the existence of noradrenergic afferents onto CRNs from the locus coeruleus by combining tyrosine hydroxylase immunohistochemistry and tract-tracing experiments. Our results provide valuable information toward understanding how CRNs might integrate excitatory and inhibitory inputs, and hence how they could elicit and modulate the ASR.
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Affiliation(s)
- R Gómez-Nieto
- Laboratorio de Neurobiología de la Audición, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Alfonso X El Sabio s/n, 37007 Salamanca, Spain
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Rousseaux CG. A Review of Glutamate Receptors II: Pathophysiology and Pathology. J Toxicol Pathol 2008. [DOI: 10.1293/tox.21.133] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Colin G. Rousseaux
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of Ottawa
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49
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Wang Y, Pang YW, Dong YL, Zhang FX, Li JL, Li YQ. Localization of vesicular glutamate transporters in the peripheral vestibular system of rat. Neurosci Bull 2007; 23:175-9. [PMID: 17612597 PMCID: PMC5550633 DOI: 10.1007/s12264-007-0026-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVE To examine the vesicular glutamate transporters (VGluTs: VGluT1-VGluT3) in the peripheral vestibular system. METHODS The vestibular structures, including Scarpa's ganglion (vestibular ganglion, VG), maculae of utricle and saccule, and ampullary cristae, from normal Sprague-Dawley rats were processed immunohistochemically for VGluTs, by avidin-biotinylated peroxidase complex method, with 3-3'-diaminobenzidine (DAB) as chromogen. RESULTS (1) VGluT1 was localized to partial neurons of VG and to the putative primary afferent fibers innervating vestibular end-organs. (2) Intense VGluT3 immunoreactivity was detected in large number of sensory epithelia cells, and weak labeling of VGluT3-positive afferent fibers was in the maculae and ampullary cristae. (3) No or very weak VGluT2 immunoreactivity was observed in the VG and acoustic maculae. CONCLUSION These results provide the morphological support that glutamate exists in the peripheral vestibular system, and it may play an important role in the centripetal vestibular transmission.
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Affiliation(s)
- Yuan Wang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
- Department of Stomatology, The Fourth Military Medical University, Xi’an, 710032 China
| | - You-Wang Pang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
- Department of Orthopaedics, The 180th Hospital of PLA, Quanzhou, 362000 China
| | - Yu-Lin Dong
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
| | - Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, 710032 China
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Khan AF, Thorne PR, Muñoz DJB, Wang CJH, Housley GD, Vlajkovic SM. Nucleoside transporter expression and adenosine uptake in the rat cochlea. Neuroreport 2007; 18:235-9. [PMID: 17314663 DOI: 10.1097/wnr.0b013e3280115918] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Even though extracellular adenosine plays multiple roles in the cochlea, the mechanisms that control extracellular adenosine concentrations in this organ are unclear. This study investigated the expression of nucleoside transporters and adenosine uptake in the rat cochlea. Reverse transcription-polymerase chain reaction revealed the expression of mRNA transcripts for two equilibrative (ENT1 and ENT2) and two concentrative (CNT1 and CNT2) nucleoside transporters. Exogenous adenosine perfused through the cochlear perilymphatic compartment was taken up by cells lining the compartment. Adenosine uptake was sensitive to changes in extracellular Na concentrations and inhibited by nitrobenzylthioinosine (an adenosine uptake blocker). The study suggests that the bi-directional nucleoside transport supports the uptake and recycling of purines and regulates the activation of adenosine receptors by altering adenosine concentrations in cochlear fluid spaces.
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Affiliation(s)
- Abdul F Khan
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
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