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Bizup B, Brutsaert S, Cunningham CL, Thathiah A, Tzounopoulos T. Cochlear zinc signaling dysregulation is associated with noise-induced hearing loss, and zinc chelation enhances cochlear recovery. Proc Natl Acad Sci U S A 2024; 121:e2310561121. [PMID: 38354264 PMCID: PMC10895357 DOI: 10.1073/pnas.2310561121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/08/2024] [Indexed: 02/16/2024] Open
Abstract
Exposure to loud noise triggers sensory organ damage and degeneration that, in turn, leads to hearing loss. Despite the troublesome impact of noise-induced hearing loss (NIHL) in individuals and societies, treatment strategies that protect and restore hearing are few and insufficient. As such, identification and mechanistic understanding of the signaling pathways involved in NIHL are required. Biological zinc is mostly bound to proteins, where it plays major structural or catalytic roles; however, there is also a pool of unbound, mobile (labile) zinc. Labile zinc is mostly found in vesicles in secretory tissues, where it is released and plays a critical signaling role. In the brain, labile zinc fine-tunes neurotransmission and sensory processing. However, injury-induced dysregulation of labile zinc signaling contributes to neurodegeneration. Here, we tested whether zinc dysregulation occurs and contributes to NIHL in mice. We found that ZnT3, the vesicular zinc transporter responsible for loading zinc into vesicles, is expressed in cochlear hair cells and the spiral limbus, with labile zinc also present in the same areas. Soon after noise trauma, ZnT3 and zinc levels are significantly increased, and their subcellular localization is vastly altered. Disruption of zinc signaling, either via ZnT3 deletion or pharmacological zinc chelation, mitigated NIHL, as evidenced by enhanced auditory brainstem responses, distortion product otoacoustic emissions, and number of hair cell synapses. These data reveal that noise-induced zinc dysregulation is associated with cochlear dysfunction and recovery after NIHL, and point to zinc chelation as a potential treatment for mitigating NIHL.
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Affiliation(s)
- Brandon Bizup
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Sofie Brutsaert
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Christopher L Cunningham
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Amantha Thathiah
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Thanos Tzounopoulos
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
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2
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Wang X, Fan Q, Yu X, Wang Y. Cellular distribution of the Fragile X mental retardation protein in the inner ear: a developmental and comparative study in the mouse, rat, gerbil, and chicken. J Comp Neurol 2023; 531:149-169. [PMID: 36222577 PMCID: PMC9691623 DOI: 10.1002/cne.25420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 09/08/2022] [Accepted: 09/16/2022] [Indexed: 11/11/2022]
Abstract
The Fragile X mental retardation protein (FMRP) is an mRNA binding protein that is essential for neural circuit assembly and synaptic plasticity. Loss of functional FMRP leads to Fragile X syndrome (FXS), a neurodevelopmental disorder characterized by sensory dysfunction including abnormal auditory processing. While the central mechanisms of FMRP regulation have been studied in the brain, whether FMRP is expressed in the auditory periphery and how it develops and functions remains unknown. In this study, we characterized the spatiotemporal distribution pattern of FMRP immunoreactivity in the inner ear of mice, rats, gerbils, and chickens. Across species, FMRP was expressed in hair cells and supporting cells, with a particularly high level in immature hair cells during the prehearing period. Interestingly, the distribution of cytoplasmic FMRP displayed an age-dependent translocation in hair cells, and this feature was conserved across species. In the auditory ganglion (AG), FMRP immunoreactivity was detected in neuronal cell bodies as well as their peripheral and central processes. Distinct from hair cells, FMRP intensity in AG neurons was high both during development and after maturation. Additionally, FMRP was evident in mature glial cells surrounding AG neurons. Together, these observations demonstrate distinct developmental trajectories across cell types in the auditory periphery. Given the importance of peripheral inputs to the maturation of auditory circuits, these findings implicate involvement of FMRP in inner ear development as well as a potential contribution of periphery FMRP to the generation of auditory dysfunction in FXS.
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Affiliation(s)
- Xiaoyu Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, College of Medicine, Jinan University, Guangzhou 510632, China
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Qiwei Fan
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, College of Medicine, Jinan University, Guangzhou 510632, China
| | - Xiaoyan Yu
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Yuan Wang
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
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3
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Mukherjee S, Kuroiwa M, Oakden W, Paul BT, Noman A, Chen J, Lin V, Dimitrijevic A, Stanisz G, Le TN. Local magnetic delivery of adeno-associated virus AAV2(quad Y-F)-mediated BDNF gene therapy restores hearing after noise injury. Mol Ther 2022; 30:519-533. [PMID: 34298130 PMCID: PMC8821893 DOI: 10.1016/j.ymthe.2021.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 05/11/2021] [Accepted: 07/14/2021] [Indexed: 02/04/2023] Open
Abstract
Moderate noise exposure may cause acute loss of cochlear synapses without affecting the cochlear hair cells and hearing threshold; thus, it remains "hidden" to standard clinical tests. This cochlear synaptopathy is one of the main pathologies of noise-induced hearing loss (NIHL). There is no effective treatment for NIHL, mainly because of the lack of a proper drug-delivery technique. We hypothesized that local magnetic delivery of gene therapy into the inner ear could be beneficial for NIHL. In this study, we used superparamagnetic iron oxide nanoparticles (SPIONs) and a recombinant adeno-associated virus (AAV) vector (AAV2(quad Y-F)) to deliver brain-derived neurotrophic factor (BDNF) gene therapy into the rat inner ear via minimally invasive magnetic targeting. We found that the magnetic targeting effectively accumulates and distributes the SPION-tagged AAV2(quad Y-F)-BDNF vector into the inner ear. We also found that AAV2(quad Y-F) efficiently transfects cochlear hair cells and enhances BDNF gene expression. Enhanced BDNF gene expression substantially recovers noise-induced BDNF gene downregulation, auditory brainstem response (ABR) wave I amplitude reduction, and synapse loss. These results suggest that magnetic targeting of AAV2(quad Y-F)-mediated BDNF gene therapy could reverse cochlear synaptopathy after NIHL.
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Affiliation(s)
- Subhendu Mukherjee
- Biological Sciences Platform, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Maya Kuroiwa
- Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, University of Toronto, ON M5S 1A1, Canada
| | - Wendy Oakden
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Brandon T. Paul
- Evaluative Clinical Sciences Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Ayesha Noman
- Biological Sciences Platform, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Joseph Chen
- Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, University of Toronto, ON M5S 1A1, Canada
| | - Vincent Lin
- Biological Sciences Platform, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada,Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, University of Toronto, ON M5S 1A1, Canada
| | - Andrew Dimitrijevic
- Evaluative Clinical Sciences Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada,Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, University of Toronto, ON M5S 1A1, Canada
| | - Greg Stanisz
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - Trung N. Le
- Biological Sciences Platform, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada,Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, University of Toronto, ON M5S 1A1, Canada,Corresponding author: Trung N. Le, Biological Sciences Platform, Hurvitz Brain Sciences Program, Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Room M1 102, Toronto, ON M4N 3M5, Canada.
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4
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Lin X, Luo J, Tan J, Yang L, Wang M, Li P. Experimental animal models of drug-induced sensorineural hearing loss: a narrative review. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1393. [PMID: 34733945 PMCID: PMC8506545 DOI: 10.21037/atm-21-2508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 08/16/2021] [Indexed: 01/19/2023]
Abstract
Objective This narrative review describes experimental animal models of sensorineural hearing loss (SNHL) caused by ototoxic agents. Background SNHL primarily results from damage to the sensory organ within the inner ear or the vestibulocochlear nerve (cranial nerve VIII). The main etiology of SNHL includes genetic diseases, presbycusis, ototoxic agents, infection, and noise exposure. Animal models with functional and anatomic damage to the sensory organ within the inner ear or the vestibulocochlear nerve mimicking the damage seen in humans are employed to explore the mechanism and potential treatment of SNHL. These animal models of SNHL are commonly established using ototoxic agents. Methods A literature search of PubMed, Embase, and Web of Science was performed for research articles on hearing loss and ototoxic agents in animal models of hearing loss. Conclusions Common ototoxic medications such as aminoglycoside antibiotics (AABs) and platinum antitumor drugs are extensively used to induce SNHL in experimental animals. The effect of ototoxic agents in vivo is influenced by the chemical mechanisms of the ototoxic agents, the species of animal, routes of administration of the ototoxic agents, and the dosage of ototoxic agents. Animal models of drug-induced SNHL contribute to understanding the hearing mechanism and reveal the function of different parts of the auditory system in humans.
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Affiliation(s)
- Xuexin Lin
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jia Luo
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jingqian Tan
- Department of Otolaryngology Head and Neck Surgery, The Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Luoying Yang
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Mitian Wang
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University Yuedong Hospital, Meizhou, China
| | - Peng Li
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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5
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Peixoto Pinheiro B, Adel Y, Knipper M, Müller M, Löwenheim H. Auditory Threshold Variability in the SAMP8 Mouse Model of Age-Related Hearing Loss: Functional Loss and Phenotypic Change Precede Outer Hair Cell Loss. Front Aging Neurosci 2021; 13:708190. [PMID: 34408646 PMCID: PMC8366269 DOI: 10.3389/fnagi.2021.708190] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
Age-related hearing loss (ARHL) is the most common sensory deficit in aging society, which is accompanied by increased speech discrimination difficulties in noisy environments, social isolation, and cognitive decline. The audiometric degree of ARHL is largely correlated with sensory hair cell loss in addition to age-related factors not captured by histopathological analysis of the human cochlea. Previous studies have identified the senescence-accelerated mouse prone strain 8 (SAMP8) as a model for studying ARHL and age-related modifications of the cochlear redox environment. However, the SAMP8 population exhibits a large variability in auditory function decline over age, whose underlying cause remains unknown. In this study, we analyzed auditory function of SAMP8 mice by measuring auditory brainstem response (ABR) thresholds at the age of 6 weeks (juvenile), 12 weeks (young adult), and 24 weeks (adult). Consistent with previous studies, SAMP8 mice exhibit an early progressive, age-related decline of hearing acuity. However, a spatiotemporal cytohistological analysis showed that the significant increase in threshold variability was not concurrently reflected in outer hair cell (OHC) loss observed in the lower and upper quartiles of the ABR threshold distributions over age. This functional loss was found to precede OHC loss suggesting that age-related phenotypic changes may be contributing factors not represented in cytohistological analysis. The expression of potassium channels KCNQ4 (KV7.4), which mediates the current IK,n crucial for the maintenance of OHC membrane potential, and KCNQ1 (KV7.1), which is an essential component in potassium circulation and secretion into the endolymph generating the endocochlear potential, showed differences between these quartiles and age groups. This suggests that phenotypic changes in OHCs or the stria vascularis due to variable oxidative deficiencies in individual mice may be predictors of the observed threshold variability in SAMP8 mice and their progressive ARHL. In future studies, further phenotypic predictors affected by accumulated metabolic challenges over age need to be investigated as potentially underlying causes of ARHL preceding irreversible OHC loss in the SAMP8 mouse model.
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Affiliation(s)
- Barbara Peixoto Pinheiro
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
| | - Youssef Adel
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
| | - Marlies Knipper
- Molecular Physiology of Hearing, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
| | - Marcus Müller
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
| | - Hubert Löwenheim
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
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6
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Marchetta P, Rüttiger L, Hobbs AJ, Singer W, Knipper M. The role of cGMP signalling in auditory processing in health and disease. Br J Pharmacol 2021; 179:2378-2393. [PMID: 33768519 DOI: 10.1111/bph.15455] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 11/29/2022] Open
Abstract
cGMP is generated by the cGMP-forming guanylyl cyclases (GCs), the intracellular nitric oxide (NO)-sensitive (soluble) guanylyl cyclase (sGC) and transmembrane GC (e.g. GC-A and GC-B). In summarizing the particular role of cGMP signalling for hearing, we show that GC generally do not interfere significantly with basic hearing function but rather sustain a healthy state for proper temporal coding, fast discrimination and adjustments during injury. sGC is critical for the integrity of the first synapse in the ascending auditory pathway, the inner hair cell synapse. GC-A promotes hair cell stability under stressful conditions such as acoustic trauma or ageing. GC-B plays a role in the development of efferent feed-back and gain control. Regarding the crucial role hearing has for language development, speech discrimination and cognitive brain functions, differential pharmaceutical targeting of GCs offers therapeutic promise for the restoration of hearing.
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Affiliation(s)
- Philine Marchetta
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Adrian J Hobbs
- William Harvey Research Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London, London, UK
| | - Wibke Singer
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Marlies Knipper
- Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
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7
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Lopez-Juarez A, Gonzalez-Vega A, Kleinert-Altamirano A, Piazza V, Garduno-Robles A, Alata M, Villaseñor-Mora C, Eguibar JR, Cortes C, Padierna LC, Hernandez VH. Auditory impairment in H-ABC tubulinopathy. J Comp Neurol 2020; 529:957-968. [PMID: 32681585 DOI: 10.1002/cne.24990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/12/2020] [Accepted: 07/10/2020] [Indexed: 12/20/2022]
Abstract
Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a neurodegenerative disease due to mutations in TUBB4A. Patients suffer from extrapyramidal movements, spasticity, ataxia, and cognitive deficits. Magnetic resonance imaging features are hypomyelination and atrophy of the striatum and cerebellum. A correlation between the mutations and their cellular, tissue and organic effects is largely missing. The effects of these mutations on sensory functions have not been described so far. We have previously reported a rat carrying a TUBB4A (A302T) mutation and sharing most of the clinical and radiological signs with H-ABC patients. Here, for the first time, we did a comparative study of the hearing function in an H-ABC patient and in this mutant model. By analyzing hearing function, we found that there are no significant differences in the auditory brainstem response (ABR) thresholds between mutant rats and WT controls. Nevertheless, ABRs show longer latencies in central waves (II-IV) that in some cases disappear when compared to WT. The patient also shows abnormal AEPs presenting only Waves I and II. Distortion product of otoacoustic emissions and immunohistochemistry in the rat show that the peripheral hearing function and morphology of the organ of Corti are normal. We conclude that the tubulin mutation severely impairs the central hearing pathway most probably by progressive central white matter degeneration. Hearing function might be affected in a significant fraction of patients with H-ABC; therefore, screening for auditory function should be done on patients with tubulinopathies to evaluate hearing support therapies.
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Affiliation(s)
| | - Arturo Gonzalez-Vega
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | | | | | - Angeles Garduno-Robles
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico.,Center of Research in Optics, Leon, Mexico
| | | | | | - Jose R Eguibar
- Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.,Vicerrectoría de Investigación y Estudios de Posgrado, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Carmen Cortes
- Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Luis Carlos Padierna
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | - Victor H Hernandez
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
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8
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Kamerer AM, Kopun JG, Fultz SE, Neely ST, Rasetshwane DM. Reliability of Measures Intended to Assess Threshold-Independent Hearing Disorders. Ear Hear 2020; 40:1267-1279. [PMID: 30882533 PMCID: PMC6745005 DOI: 10.1097/aud.0000000000000711] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES Recent animal studies have shown that noise exposure can cause cochlear synaptopathy without permanent threshold shift. Because the noise exposure preferentially damaged auditory nerve fibers that processed suprathreshold sounds (low-spontaneous rate fibers), it has been suggested that synaptopathy may underlie suprathreshold hearing deficits in humans. Recently, several researchers have suggested measures to identify the pathology or pathologies underlying suprathreshold hearing deficits in humans based on results from animal studies; however, the reliability of some of these measures have not been assessed. The purpose of this study was to assess the test-retest reliability of measures that may have the potential to relate suprathreshold hearing deficits to site(s)-of-lesion along the peripheral auditory system in humans. DESIGN Adults with audiometric normal hearing were tested on a battery of behavioral and physiologic measures that included (1) thresholds in quiet (TIQ), (2) thresholds in noise (TIN), (3) frequency-modulation detection threshold (FMDT), (4) word recognition in four listening conditions, (5) distortion-product otoacoustic emissions (DPOAE), (6) middle ear muscle reflex (MEMR), (7) tone burst-elicited auditory brainstem response (tbABR), and (8) speech-evoked ABR (sABR). Data collection for each measure was repeated over two visits separated by at least one week. The residuals of the correlation between the suprathreshold measures and TIQ serve as functional and quantitative proxies for threshold-independent hearing disorders because they represent the portion of the raw measures that is not dependent on TIQ. Reliability of the residual measures was assessed using intraclass correlation (ICC). RESULTS Reliability for the residual measures was good (ICC ≥ 0.75) for FMDT, DPOAEs, and MEMR. Residual measures showing moderate reliability (0.5 ≤ ICC < 0.75) were tbABR wave I amplitude, TIN, and word recognition in quiet, noise, and time-compressed speech with reverberation. Wave V of the tbABR, waves of the sABR, and recognition of time-compressed words had poor test-retest reliability (ICC < 0.5). CONCLUSIONS Reliability of residual measures was mixed, suggesting that care should be taken when selecting measures for diagnostic tests of threshold-independent hearing disorders. Quantifying hidden hearing loss as the variance in suprathreshold measures of auditory function that is not due to TIQ may provide a reliable estimate of threshold-independent hearing disorders in humans.
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Affiliation(s)
| | - Judy G. Kopun
- Boys Town National Research Hospital, Omaha, NE 68131
| | - Sara E. Fultz
- Boys Town National Research Hospital, Omaha, NE 68131
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9
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Marchetta P, Möhrle D, Eckert P, Reimann K, Wolter S, Tolone A, Lang I, Wolters M, Feil R, Engel J, Paquet-Durand F, Kuhn M, Knipper M, Rüttiger L. Guanylyl Cyclase A/cGMP Signaling Slows Hidden, Age- and Acoustic Trauma-Induced Hearing Loss. Front Aging Neurosci 2020; 12:83. [PMID: 32327991 PMCID: PMC7160671 DOI: 10.3389/fnagi.2020.00083] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/10/2020] [Indexed: 12/24/2022] Open
Abstract
In the inner ear, cyclic guanosine monophosphate (cGMP) signaling has been described as facilitating otoprotection, which was previously observed through elevated cGMP levels achieved by phosphodiesterase 5 inhibition. However, to date, the upstream guanylyl cyclase (GC) subtype eliciting cGMP production is unknown. Here, we show that mice with a genetic disruption of the gene encoding the cGMP generator GC-A, the receptor for atrial and B-type natriuretic peptides, display a greater vulnerability of hair cells to hidden hearing loss and noise- and age-dependent hearing loss. This vulnerability was associated with GC-A expression in spiral ganglia and outer hair cells (OHCs) but not in inner hair cells (IHCs). GC-A knockout mice exhibited elevated hearing thresholds, most pronounced for the detection of high-frequency tones. Deficits in OHC input–output functions in high-frequency regions were already present in young GC-A-deficient mice, with no signs of an accelerated progression of age-related hearing loss or higher vulnerability to acoustic trauma. OHCs in these frequency regions in young GC-A knockout mice exhibited diminished levels of KCNQ4 expression, which is the dominant K+ channel in OHCs, and decreased activation of poly (ADP-ribose) polymerase-1, an enzyme involved in DNA repair. Further, GC-A knockout mice had IHC synapse impairments and reduced amplitudes of auditory brainstem responses that progressed with age and with acoustic trauma, in contrast to OHCs, when compared to GC-A wild-type littermates. We conclude that GC-A/cGMP-dependent signaling pathways have otoprotective functions and GC-A gene disruption differentially contributes to hair-cell damage in a healthy, aged, or injured system. Thus, augmentation of natriuretic peptide GC-A signaling likely has potential to overcome hidden and noise-induced hearing loss, as well as presbycusis.
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Affiliation(s)
- Philine Marchetta
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
| | - Dorit Möhrle
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Philipp Eckert
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
| | - Katrin Reimann
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
| | - Steffen Wolter
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
| | - Arianna Tolone
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Isabelle Lang
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, Hearing Research, Saarland University, Homburg, Germany
| | - Markus Wolters
- Signal Transduction and Transgenic Models, Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Robert Feil
- Signal Transduction and Transgenic Models, Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Jutta Engel
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, Hearing Research, Saarland University, Homburg, Germany
| | - François Paquet-Durand
- Cell Death Mechanisms Group, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Marlies Knipper
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Molecular Physiology of Hearing, Tübingen Hearing Research Centre, Department of Otolaryngology, University of Tübingen, Tübingen, Germany
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10
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Harasztosi C, Wolter S, Gutsche K, Durán-Alonso MB, López-Hernández I, Pascual A, López-Barneo J, Knipper M, Rüttiger L, Schimmang T. Differential deletion of GDNF in the auditory system leads to altered sound responsiveness. J Neurosci Res 2019; 98:1764-1779. [PMID: 31663646 DOI: 10.1002/jnr.24544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 09/20/2019] [Accepted: 10/08/2019] [Indexed: 11/09/2022]
Abstract
Glial-derived neurotrophic factor (GDNF) has been proposed as a potent neurotrophic factor with the potential to cure neurodegenerative diseases. In the cochlea, GDNF has been detected in auditory neurons and sensory receptor cells and its expression is upregulated upon trauma. Moreover, the application of GDNF in different animal models of deafness has shown its capacity to prevent hearing loss and promoted its future use in therapeutic trials in humans. In the present study we have examined the endogenous requirement of GDNF during auditory development in mice. Using a lacZ knockin allele we have confirmed the expression of GDNF in the cochlea including its sensory regions during development. Global inactivation of GDNF throughout the hearing system using a Foxg1-Cre line causes perinatal lethality but reveals no apparent defects during formation of the cochlea. Using TrkC-Cre and Atoh1-Cre lines, we were able to generate viable mutants lacking GDNF in auditory neurons or both auditory neurons and sensory hair cells. These mutants show normal frequency-dependent auditory thresholds. However, mechanoelectrical response properties of outer hair cells (OHCs) in TrkC-Cre GDNF mutants are altered at low thresholds. Furthermore, auditory brainstem wave analysis shows an abnormal increase of wave I. On the other hand, Atoh1-Cre GDNF mutants show normal OHC function but their auditory brainstem wave pattern is reduced at the levels of wave I, III and IV. These results show that GDNF expression during the development is required to maintain functional hearing at different levels of the auditory system.
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Affiliation(s)
- Csaba Harasztosi
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Steffen Wolter
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Katja Gutsche
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - María Beatriz Durán-Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - Iris López-Hernández
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - Alberto Pascual
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/, Universidad de Sevilla, Seville, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/, Universidad de Sevilla, Seville, Spain
| | - Marlies Knipper
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Thomas Schimmang
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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11
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Ridley CL, Kopun JG, Neely ST, Gorga MP, Rasetshwane DM. Using Thresholds in Noise to Identify Hidden Hearing Loss in Humans. Ear Hear 2019; 39:829-844. [PMID: 29337760 PMCID: PMC6046280 DOI: 10.1097/aud.0000000000000543] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Recent animal studies suggest that noise-induced synaptopathy may underlie a phenomenon that has been labeled hidden hearing loss (HHL). Noise exposure preferentially damages low spontaneous-rate auditory nerve fibers, which are involved in the processing of moderate- to high-level sounds and are more resistant to masking by background noise. Therefore, the effect of synaptopathy may be more evident in suprathreshold measures of auditory function, especially in the presence of background noise. The purpose of this study was to develop a statistical model for estimating HHL in humans using thresholds in noise as the outcome variable and measures that reflect the integrity of sites along the auditory pathway as explanatory variables. Our working hypothesis is that HHL is evident in the portion of the variance observed in thresholds in noise that is not dependent on thresholds in quiet, because this residual variance retains statistical dependence on other measures of suprathreshold function. DESIGN Study participants included 13 adults with normal hearing (≤15 dB HL) and 20 adults with normal hearing at 1 kHz and sensorineural hearing loss at 4 kHz (>15 dB HL). Thresholds in noise were measured, and the residual of the correlation between thresholds in noise and thresholds in quiet, which we refer to as thresholds-in-noise residual, was used as the outcome measure for the model. Explanatory measures were as follows: (1) auditory brainstem response (ABR) waves I and V amplitudes; (2) electrocochleographic action potential and summating potential amplitudes; (3) distortion product otoacoustic emissions level; and (4) categorical loudness scaling. All measurements were made at two frequencies (1 and 4 kHz). ABR and electrocochleographic measurements were made at 80 and 100 dB peak equivalent sound pressure level, while wider ranges of levels were tested during distortion product otoacoustic emission and categorical loudness scaling measurements. A model relating the thresholds-in-noise residual and the explanatory measures was created using multiple linear regression analysis. RESULTS Predictions of thresholds-in-noise residual using the model accounted for 61% (p < 0.01) and 48% (p < 0.01) of the variance in the measured thresholds-in-noise residual at 1 and 4 kHz, respectively. CONCLUSIONS Measures of thresholds in noise, the summating potential to action potential ratio, and ABR waves I and V amplitudes may be useful for the prediction of HHL in humans. With further development, our approach of quantifying HHL by the variance that remains in suprathreshold measures of auditory function after removing the variance due to thresholds in quiet, together with our statistical modeling, may provide a quantifiable and verifiable estimate of HHL in humans with normal hearing and with hearing loss. The current results are consistent with the view that inner hair cell and auditory nerve pathology may underlie suprathreshold auditory performance.
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Affiliation(s)
- Courtney L. Ridley
- Center for Hearing Research, Boys Town National Research Hospital, 555 North 30 St, Omaha, Nebraska 68131, USA
- Department of Speech, Language, and Hearing Sciences, University of Florida, 1225 Center Drive, Gainesville, FL 32610, USA
| | - Judy G. Kopun
- Center for Hearing Research, Boys Town National Research Hospital, 555 North 30 St, Omaha, Nebraska 68131, USA
| | - Stephen T. Neely
- Center for Hearing Research, Boys Town National Research Hospital, 555 North 30 St, Omaha, Nebraska 68131, USA
| | - Michael P. Gorga
- Center for Hearing Research, Boys Town National Research Hospital, 555 North 30 St, Omaha, Nebraska 68131, USA
| | - Daniel M. Rasetshwane
- Center for Hearing Research, Boys Town National Research Hospital, 555 North 30 St, Omaha, Nebraska 68131, USA
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12
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Lower ototoxicity and absence of hidden hearing loss point to gentamicin C1a and apramycin as promising antibiotics for clinical use. Sci Rep 2019; 9:2410. [PMID: 30787404 PMCID: PMC6382871 DOI: 10.1038/s41598-019-38634-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/29/2018] [Indexed: 11/08/2022] Open
Abstract
Spread of antimicrobial resistance and shortage of novel antibiotics have led to an urgent need for new antibacterials. Although aminoglycoside antibiotics (AGs) are very potent anti-infectives, their use is largely restricted due to serious side-effects, mainly nephrotoxicity and ototoxicity. We evaluated the ototoxicity of various AGs selected from a larger set of AGs on the basis of their strong antibacterial activities against multidrug-resistant clinical isolates of the ESKAPE panel: gentamicin, gentamicin C1a, apramycin, paromomycin and neomycin. Following local round window application, dose-dependent effects of AGs on outer hair cell survival and compound action potentials showed gentamicin C1a and apramycin as the least toxic. Strikingly, although no changes were observed in compound action potential thresholds and outer hair cell survival following treatment with low concentrations of neomycin, gentamicin and paromomycin, the number of inner hair cell synaptic ribbons and the compound action potential amplitudes were reduced. This indication of hidden hearing loss was not observed with gentamicin C1a or apramycin at such concentrations. These findings identify the inner hair cells as the most vulnerable element to AG treatment, indicating that gentamicin C1a and apramycin are promising bases for the development of clinically useful antibiotics.
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13
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Möhrle D, Hofmeier B, Amend M, Wolpert S, Ni K, Bing D, Klose U, Pichler B, Knipper M, Rüttiger L. Enhanced Central Neural Gain Compensates Acoustic Trauma-induced Cochlear Impairment, but Unlikely Correlates with Tinnitus and Hyperacusis. Neuroscience 2018; 407:146-169. [PMID: 30599268 DOI: 10.1016/j.neuroscience.2018.12.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 01/09/2023]
Abstract
For successful future therapeutic strategies for tinnitus and hyperacusis, a subcategorization of both conditions on the basis of differentiated neural correlates would be of invaluable advantage. In the present study, we used our refined operant conditioning animal model to divide equally noise-exposed rats into groups with either tinnitus or hyperacusis, with neither condition, or with both conditions co-occurring simultaneously. Using click stimulus and noise burst-evoked Auditory Brainstem Responses (ABR) and Distortion Product Otoacoustic Emissions, no hearing threshold difference was observed between any of the groups. However, animals with neither tinnitus nor hyperacusis responded to noise trauma with shortened ABR wave I and IV latencies and elevated central neuronal gain (increased ABR wave IV/I amplitude ratio), which was previously assumed in most of the literature to be a neural correlate for tinnitus. In contrast, animals with tinnitus had reduced neural response gain and delayed ABR wave I and IV latencies, while animals with hyperacusis showed none of these changes. Preliminary studies, aimed at establishing comparable non-invasive objective tools for identifying tinnitus in humans and animals, confirmed reduced central gain and delayed response latency in human and animals. Moreover, the first ever resting state functional Magnetic Resonance Imaging (rs-fMRI) analyses comparing humans and rats with and without tinnitus showed reduced rs-fMRI activities in the auditory cortex in both patients and animals with tinnitus. These findings encourage further efforts to establish non-invasive diagnostic tools that can be used in humans and animals alike and give hope for differentiated classification of tinnitus and hyperacusis.
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Affiliation(s)
- Dorit Möhrle
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
| | - Benedikt Hofmeier
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
| | - Mario Amend
- University of Tübingen, Department of Preclinical Imaging and Radiopharmacy, University Hospital Tübingen, Röntgenweg 13, 72076 Tübingen, Germany.
| | - Stephan Wolpert
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
| | - Kun Ni
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany; Shanghai Jiao Tong University, Department of Otolaryngology, Head & Neck Surgery, Shanghai Children's Hospital, Shanghai Luding Road, NO. 355. Putuo District, 200062 Shanghai, China.
| | - Dan Bing
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
| | - Uwe Klose
- University Hospital Tübingen, Department of Diagnostic and Interventional Neuroradiology, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany.
| | - Bernd Pichler
- University of Tübingen, Department of Preclinical Imaging and Radiopharmacy, University Hospital Tübingen, Röntgenweg 13, 72076 Tübingen, Germany.
| | - Marlies Knipper
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
| | - Lukas Rüttiger
- University of Tübingen, Department of Otolaryngology, Head & Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany.
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14
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Singer W, Kasini K, Manthey M, Eckert P, Armbruster P, Vogt MA, Jaumann M, Dotta M, Yamahara K, Harasztosi C, Zimmermann U, Knipper M, Rüttiger L. The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats. FASEB J 2018; 32:3005-3019. [PMID: 29401591 DOI: 10.1096/fj.201701041rrr] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Systemic corticosteroids have been the mainstay of treatment for various hearing disorders for more than 30 yr. Accordingly, numerous studies have described glucocorticoids (GCs) and stressors to be protective in the auditory organ against damage associated with a variety of health conditions, including noise exposure. Conversely, stressors are also predictive risk factors for hearing disorders. How both of these contrasting stress actions are linked has remained elusive. Here, we demonstrate that higher corticosterone levels during acoustic trauma in female rats is highly correlated with a decline of auditory fiber responses in high-frequency cochlear regions, and that hearing thresholds and the outer hair cell functions (distortion products of otoacoustic emissions) are left unaffected. Moreover, when GC receptor (GR) or mineralocorticoid receptor (MR) activation was antagonized by mifepristone or spironolactone, respectively, GR, but not MR, inhibition significantly and permanently attenuated trauma-induced effects on auditory fiber responses, including inner hair cell ribbon loss and related reductions of early and late auditory brainstem responses. These findings strongly imply that higher corticosterone stress levels profoundly impair auditory nerve processing, which may influence central auditory acuity. These changes are likely GR mediated as they are prevented by mifepristone.-Singer, W., Kasini, K., Manthey, M., Eckert, P., Armbruster, P., Vogt, M. A., Jaumann, M., Dotta, M., Yamahara, K., Harasztosi, C., Zimmermann, U., Knipper, M., Rüttiger, L. The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats.
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Affiliation(s)
- Wibke Singer
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Kamyar Kasini
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Marie Manthey
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Philipp Eckert
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Philipp Armbruster
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Miriam Annika Vogt
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Mirko Jaumann
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Michela Dotta
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Kohei Yamahara
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany.,Section of Physiological Acoustics and Communication, Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Csaba Harasztosi
- Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Ulrike Zimmermann
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Marlies Knipper
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Molecular Physiology of Hearing, Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany
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15
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Möhrle D, Reimann K, Wolter S, Wolters M, Varakina K, Mergia E, Eichert N, Geisler HS, Sandner P, Ruth P, Friebe A, Feil R, Zimmermann U, Koesling D, Knipper M, Rüttiger L. NO-Sensitive Guanylate Cyclase Isoforms NO-GC1 and NO-GC2 Contribute to Noise-Induced Inner Hair Cell Synaptopathy. Mol Pharmacol 2017; 92:375-388. [DOI: 10.1124/mol.117.108548] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 12/21/2022] Open
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16
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Auditory Neuropathy after Damage to Cochlear Spiral Ganglion Neurons in Mice Resulting from Conditional Expression of Diphtheria Toxin Receptors. Sci Rep 2017; 7:6409. [PMID: 28743950 PMCID: PMC5527113 DOI: 10.1038/s41598-017-06600-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 06/15/2017] [Indexed: 01/08/2023] Open
Abstract
Auditory neuropathy (AN) is a hearing disorder characterized by normal cochlear amplification to sound but poor temporal processing and auditory perception in noisy backgrounds. These deficits likely result from impairments in auditory neural synchrony; such dyssynchrony of the neural responses has been linked to demyelination of auditory nerve fibers. However, no appropriate animal models are currently available that mimic this pathology. In this study, Cre-inducible diphtheria toxin receptor (iDTR+/+) mice were cross-mated with mice containing Cre (Bhlhb5-Cre+/−) specific to spiral ganglion neurons (SGNs). In double-positive offspring mice, the injection of diphtheria toxin (DT) led to a 30–40% rate of death for SGNs, but no hair cell damage. Demyelination types of pathologies were observed around the surviving SGNs and their fibers, many of which were distorted in shape. Correspondingly, a significant reduction in response synchrony to amplitude modulation was observed in this group of animals compared to the controls, which had a Cre− genotype. Taken together, our results suggest that SGN damage following the injection of DT in mice with Bhlhb5-Cre+/− and iDTR+/− is likely to be a good AN model of demyelination.
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17
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Reis AD, Dalmolin SP, Dallegrave E. Modelos animais para avaliação auditiva: revisão de literatura. REVISTA CEFAC 2017. [DOI: 10.1590/1982-021620171932117] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
RESUMO O objetivo dessa revisão é delinear os modelos animais viáveis para a pesquisa pré-clínica auditiva, considerando suas características anatômicas, fisiológicas, vantagens e desvantagens. Foram consultadas as bases de dados Scielo, Pubmed e Periódicos Capes, utilizando descritores envolvendo audição, testes auditivos e espécies animais, individualmente e cruzados entre si. Foram lidos os resumos dos artigos encontrados nas bases de dados, com posterior seleção baseada nos critérios: artigos disponíveis em sua integridade, uso de modelos animais em procedimentos audiológicos que incluísse a descrição dos métodos de avaliação, as vantagens e/ou desvantagens do uso da espécie, publicados entre 1995 e 2016. Apesar da existência de modelos alternativos, os mamíferos são ainda amplamente utilizados em pesquisa. Constatou-se que os ratos, camundongos e cobaios são frequentemente utilizados e, além destes, ovelhas, coelhos e chinchilas. Os métodos para avaliação auditiva contemplam principalmente emissões otoacústicas por produto de distorção, potencial evocado auditivo de tronco encefálico e avaliação histológica, principalmente em roedores. A escolha do animal de experimentação para avaliação do sistema auditivo depende de fatores anatômicos, fisiológicos, econômicos, espaciais, psicossociais e do objetivo da avaliação.
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Affiliation(s)
- Aléxia dos Reis
- Universidade Federal de Ciências da Saúde de Porto Alegre, Brazil
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18
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Selective Inner Hair Cell Dysfunction in Chinchillas Impairs Hearing-in-Noise in the Absence of Outer Hair Cell Loss. J Assoc Res Otolaryngol 2015; 17:89-101. [PMID: 26691159 DOI: 10.1007/s10162-015-0550-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022] Open
Abstract
Poorer hearing in the presence of background noise is a significant problem for the hearing impaired. Ototoxic drugs, ageing, and noise exposure can damage the sensory hair cells of the inner ear that are essential for normal hearing sensitivity. The relationship between outer hair cell (OHC) loss and progressively poorer hearing sensitivity in quiet or in competing background noise is supported by a number of human and animal studies. In contrast, the effect of moderate inner hair cell (IHC) loss or dysfunction shows almost no impact on behavioral measures of hearing sensitivity in quiet, when OHCs remain intact, but the relationship between selective IHC loss and hearing in noise remains relatively unknown. Here, a moderately high dose of carboplatin (75 mg/kg) that produced IHC loss in chinchillas ranging from 40 to 80 % had little effect on thresholds in quiet. However, when tested in the presence of competing broadband (BBN) or narrowband noise (NBN), thresholds increased significantly. IHC loss >60 % increased signal-to-noise ratios (SNRs) for tones (500-11,300 Hz) in competing BBN by 5-10 dB and broadened the masking function under NBN. These data suggest that IHC loss or dysfunction may play a significant role in listening in noise independent of OHC integrity and that these deficits may be present even when thresholds in quiet are within normal limits.
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19
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Sharma A, Cardon G. Cortical development and neuroplasticity in Auditory Neuropathy Spectrum Disorder. Hear Res 2015; 330:221-32. [PMID: 26070426 DOI: 10.1016/j.heares.2015.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 04/27/2015] [Accepted: 06/01/2015] [Indexed: 11/28/2022]
Abstract
Cortical development is dependent to a large extent on stimulus-driven input. Auditory Neuropathy Spectrum Disorder (ANSD) is a recently described form of hearing impairment where neural dys-synchrony is the predominant characteristic. Children with ANSD provide a unique platform to examine the effects of asynchronous and degraded afferent stimulation on cortical auditory neuroplasticity and behavioral processing of sound. In this review, we describe patterns of auditory cortical maturation in children with ANSD. The disruption of cortical maturation that leads to these various patterns includes high levels of intra-individual cortical variability and deficits in cortical phase synchronization of oscillatory neural responses. These neurodevelopmental changes, which are constrained by sensitive periods for central auditory maturation, are correlated with behavioral outcomes for children with ANSD. Overall, we hypothesize that patterns of cortical development in children with ANSD appear to be markers of the severity of the underlying neural dys-synchrony, providing prognostic indicators of success of clinical intervention with amplification and/or electrical stimulation. This article is part of a Special Issue entitled <Auditory Synaptology>.
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Affiliation(s)
- Anu Sharma
- University of Colorado at Boulder, Speech, Language, and Hearing Sciences Department, Institute of Cognitive Science and Center for Neuroscience, 2501 Kittredge Loop Rd, Boulder, CO 80309, USA.
| | - Garrett Cardon
- University of Colorado at Boulder, Speech, Language, and Hearing Sciences Department, Institute of Cognitive Science and Center for Neuroscience, 2501 Kittredge Loop Rd, Boulder, CO 80309, USA
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20
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Gold JR, Bajo VM. Insult-induced adaptive plasticity of the auditory system. Front Neurosci 2014; 8:110. [PMID: 24904256 PMCID: PMC4033160 DOI: 10.3389/fnins.2014.00110] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/28/2014] [Indexed: 01/10/2023] Open
Abstract
The brain displays a remarkable capacity for both widespread and region-specific modifications in response to environmental challenges, with adaptive processes bringing about the reweighing of connections in neural networks putatively required for optimizing performance and behavior. As an avenue for investigation, studies centered around changes in the mammalian auditory system, extending from the brainstem to the cortex, have revealed a plethora of mechanisms that operate in the context of sensory disruption after insult, be it lesion-, noise trauma, drug-, or age-related. Of particular interest in recent work are those aspects of auditory processing which, after sensory disruption, change at multiple—if not all—levels of the auditory hierarchy. These include changes in excitatory, inhibitory and neuromodulatory networks, consistent with theories of homeostatic plasticity; functional alterations in gene expression and in protein levels; as well as broader network processing effects with cognitive and behavioral implications. Nevertheless, there abounds substantial debate regarding which of these processes may only be sequelae of the original insult, and which may, in fact, be maladaptively compelling further degradation of the organism's competence to cope with its disrupted sensory context. In this review, we aim to examine how the mammalian auditory system responds in the wake of particular insults, and to disambiguate how the changes that develop might underlie a correlated class of phantom disorders, including tinnitus and hyperacusis, which putatively are brought about through maladaptive neuroplastic disruptions to auditory networks governing the spatial and temporal processing of acoustic sensory information.
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Affiliation(s)
- Joshua R Gold
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
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21
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Lindblad AC, Rosenhall U, Olofsson Å, Hagerman B. Tinnitus and other auditory problems - occupational noise exposure below risk limits may cause inner ear dysfunction. PLoS One 2014; 9:e97377. [PMID: 24827149 PMCID: PMC4020865 DOI: 10.1371/journal.pone.0097377] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/19/2014] [Indexed: 11/18/2022] Open
Abstract
The aim of the investigation was to study if dysfunctions associated to the cochlea or its regulatory system can be found, and possibly explain hearing problems in subjects with normal or near-normal audiograms. The design was a prospective study of subjects recruited from the general population. The included subjects were persons with auditory problems who had normal, or near-normal, pure tone hearing thresholds, who could be included in one of three subgroups: teachers, Education; people working with music, Music; and people with moderate or negligible noise exposure, Other. A fourth group included people with poorer pure tone hearing thresholds and a history of severe occupational noise, Industry. Ntotal = 193. The following hearing tests were used: - pure tone audiometry with Békésy technique, - transient evoked otoacoustic emissions and distortion product otoacoustic emissions, without and with contralateral noise; - psychoacoustical modulation transfer function, - forward masking, - speech recognition in noise, - tinnitus matching. A questionnaire about occupations, noise exposure, stress/anxiety, muscular problems, medication, and heredity, was addressed to the participants. Forward masking results were significantly worse for Education and Industry than for the other groups, possibly associated to the inner hair cell area. Forward masking results were significantly correlated to louder matched tinnitus. For many subjects speech recognition in noise, left ear, did not increase in a normal way when the listening level was increased. Subjects hypersensitive to loud sound had significantly better speech recognition in noise at the lower test level than subjects not hypersensitive. Self-reported stress/anxiety was similar for all groups. In conclusion, hearing dysfunctions were found in subjects with tinnitus and other auditory problems, combined with normal or near-normal pure tone thresholds. The teachers, mostly regarded as a group exposed to noise below risk levels, had dysfunctions almost identical to those of the more exposed Industry group.
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Affiliation(s)
- Ann-Cathrine Lindblad
- Department of Clinical Science, Intervention and Technology, Division of Ear, Nose and Throat Diseases, Unit of Technical and Experimental Audiology, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
| | - Ulf Rosenhall
- Department of Clinical Science, Intervention and Technology, Division of Ear, Nose and Throat Diseases, Karolinska Institutet; and Department of Audiology and Neurotology, Karolinska University Hospital, Stockholm, Sweden
| | - Åke Olofsson
- Department of Clinical Science, Intervention and Technology, Division of Ear, Nose and Throat Diseases, Unit of Technical and Experimental Audiology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Hagerman
- Department of Clinical Science, Intervention and Technology, Division of Ear, Nose and Throat Diseases, Unit of Technical and Experimental Audiology, Karolinska Institutet, Stockholm, Sweden
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22
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Yates N, Robertson D, Martin-Iverson M, Rodger J. Auditory brainstem responses of ephrin-A2, ephrin-A5(-/-) and ephrin-A2A5(-/-) mice. Audiol Neurootol 2014; 19:115-26. [PMID: 24457350 DOI: 10.1159/000357029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 10/30/2013] [Indexed: 01/04/2023] Open
Abstract
Eph receptors and ephrin ligands are large families of cell surface proteins which have established roles in axonal growth and guidance. These are well characterized in the visual and somatosensory systems but are less well documented in the auditory pathway. We examined the possible functional role of two ephrin genes (ephrin-A2 and ephrin-A5) in the auditory system by measuring auditory brainstem responses (ABR) to tone bursts from 6 to 30 kHz in ephrin-A2(-/-), ephrin-A5(-/-) and ephrin-A2A5(-/-) (knockout) mice. At high frequencies, the ephrin-A2A5(-/-) mice exhibited thresholds that were significantly lower than in wild-type mice by approximately 20 dB, suggesting ephrin-A2 and ephrin-A5 may have frequency-specific effects on the auditory system. There were also alterations in ABR wave peak amplitudes that were specific to each mouse strain which suggested both peripheral and central involvement of EphA-ephrin-A signalling in auditory function.
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Affiliation(s)
- Nathanael Yates
- School of Animal Biology, University of Western Australia, Crawley, W.A., Australia
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23
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Zuccotti A, Lee SC, Campanelli D, Singer W, Satheesh SV, Patriarchi T, Geisler HS, Köpschall I, Rohbock K, Nothwang HG, Hu J, Hell JW, Schimmang T, Rüttiger L, Knipper M. L-type CaV1.2 deletion in the cochlea but not in the brainstem reduces noise vulnerability: implication for CaV1.2-mediated control of cochlear BDNF expression. Front Mol Neurosci 2013; 6:20. [PMID: 23950737 PMCID: PMC3739414 DOI: 10.3389/fnmol.2013.00020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/20/2013] [Indexed: 01/24/2023] Open
Abstract
Voltage-gated L-type Ca2+ channels (L-VGCCs) like CaV1.2 are assumed to play a crucial role for controlling release of trophic peptides including brain-derived neurotrophic factor (BDNF). In the inner ear of the adult mouse, besides the well-described L-VGCC CaV1.3, CaV1.2 is also expressed. Due to lethality of constitutive CaV1.2 knock-out mice, the function of this ion channel as well as its putative relationship to BDNF in the auditory system is entirely elusive. We recently described that BDNF plays a differential role for inner hair cell (IHC) vesicles release in normal and traumatized condition. To elucidate a presumptive role of CaV1.2 during this process, two tissue-specific conditional mouse lines were generated. To distinguish the impact of CaV1.2 on the cochlea from that on feedback loops from higher auditory centers CaV1.2 was deleted, in one mouse line, under the Pax2 promoter (CaV1.2Pax2) leading to a deletion in the spiral ganglion neurons, dorsal cochlear nucleus, and inferior colliculus. In the second mouse line, the Egr2 promoter was used for deleting CaV1.2 (CaV1.2Egr2) in auditory brainstem nuclei. In both mouse lines, normal hearing threshold and equal number of IHC release sites were observed. We found a slight reduction of auditory brainstem response wave I amplitudes in the CaV1.2Pax2 mice, but not in the CaV1.2Egr2 mice. After noise exposure, CaV1.2Pax2 mice had less-pronounced hearing loss that correlated with maintenance of ribbons in IHCs and less reduced activity in auditory nerve fibers, as well as in higher brain centers at supra-threshold sound stimulation. As reduced cochlear BDNF mRNA levels were found in CaV1.2Pax2 mice, we suggest that a CaV1.2-dependent step may participate in triggering part of the beneficial and deteriorating effects of cochlear BDNF in intact systems and during noise exposure through a pathway that is independent of CaV1.2 function in efferent circuits.
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Affiliation(s)
- Annalisa Zuccotti
- Molecular Physiology of Hearing, Hearing Research Center Tübingen, Department of Otolaryngology, University of Tübingen Tübingen, Germany
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24
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XIA LI, YIN SHANKAI. Local gene transfection in the cochlea (Review). Mol Med Rep 2013; 8:3-10. [DOI: 10.3892/mmr.2013.1496] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 12/13/2012] [Indexed: 11/06/2022] Open
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25
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Lobarinas E, Salvi R, Ding D. Insensitivity of the audiogram to carboplatin induced inner hair cell loss in chinchillas. Hear Res 2013; 302:113-20. [PMID: 23566980 DOI: 10.1016/j.heares.2013.03.012] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 03/18/2013] [Accepted: 03/22/2013] [Indexed: 11/25/2022]
Abstract
Noise trauma, aging, and ototoxicity preferentially damage the outer hair cells of the inner ear, leading to increased hearing thresholds and poorer frequency resolution. Whereas outer hair cells make synaptic connections with less than 10% of afferent auditory nerve fibers (type-II), inner hair cells make connections with over 90% of afferents (type-I). Despite these extensive connections, little is known about how selective inner hair cell loss impacts hearing. In chinchillas, moderate to high doses of the anticancer compound carboplatin produce selective inner hair cell and type-I afferent loss with little to no effect on outer hair cells. To determine the effects of carboplatin-induced inner hair cell loss on the most widely used clinical measure of hearing, the audiogram, pure-tone thresholds were determined behaviorally before and after 75 mg/kg carboplatin. Following carboplatin treatment, small effects on audiometric thresholds were observed even with extensive inner hair cell losses that exceed 80%. These results suggest that conventional audiometry is insensitive to inner hair cell loss and that only small populations of inner hair cells appear to be necessary for detecting tonal stimuli in a quiet background.
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Affiliation(s)
- Edward Lobarinas
- University of Florida, Department of Speech, Language, and Hearing Sciences, Gainesville, FL, USA.
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26
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Lack of brain-derived neurotrophic factor hampers inner hair cell synapse physiology, but protects against noise-induced hearing loss. J Neurosci 2012; 32:8545-53. [PMID: 22723694 DOI: 10.1523/jneurosci.1247-12.2012] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The precision of sound information transmitted to the brain depends on the transfer characteristics of the inner hair cell (IHC) ribbon synapse and its multiple contacting auditory fibers. We found that brain derived neurotrophic factor (BDNF) differentially influences IHC characteristics in the intact and injured cochlea. Using conditional knock-out mice (BDNF(Pax2) KO) we found that resting membrane potentials, membrane capacitance and resting linear leak conductance of adult BDNF(Pax2) KO IHCs showed a normal maturation. Likewise, in BDNF(Pax2) KO membrane capacitance (ΔC(m)) as a function of inward calcium current (I(Ca)) follows the linear relationship typical for normal adult IHCs. In contrast the maximal ΔC(m), but not the maximal size of the calcium current, was significantly reduced by 45% in basal but not in apical cochlear turns in BDNF(Pax2) KO IHCs. Maximal ΔC(m) correlated with a loss of IHC ribbons in these cochlear turns and a reduced activity of the auditory nerve (auditory brainstem response wave I). Remarkably, a noise-induced loss of IHC ribbons, followed by reduced activity of the auditory nerve and reduced centrally generated wave II and III observed in control mice, was prevented in equally noise-exposed BDNF(Pax2) KO mice. Data suggest that BDNF expressed in the cochlea is essential for maintenance of adult IHC transmitter release sites and that BDNF upholds opposing afferents in high-frequency turns and scales them down following noise exposure.
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27
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Knipper M, Müller M, Zimmermann U. Molecular Mechanism of Tinnitus. SPRINGER HANDBOOK OF AUDITORY RESEARCH 2012. [DOI: 10.1007/978-1-4614-3728-4_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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28
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Konrad-Martin D, Dille MF, McMillan G, Griest S, McDermott D, Fausti SA, Austin DF. Age-related changes in the auditory brainstem response. J Am Acad Audiol 2012; 23:18-35; quiz 74-5. [PMID: 22284838 PMCID: PMC5549623 DOI: 10.3766/jaaa.23.1.3] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE This cross-sectional study had two goals: (1) Identify and quantify the effects of aging on the auditory brainstem response (ABR); (2) Describe how click rate and hearing impairment modify effects of aging. RESEARCH DESIGN AND ANALYSIS: ABR measures were obtained from 131 predominately male Veteran participants aged 26 to 71 yr. Metrics analyzed include amplitude and latency for waves I, III, and V, and the I-V interpeak latency interval (IPI) at three repetition rates (11, 51, and 71 clicks/sec) using both polarities. In order to avoid confounding from missing data due to hearing impairment, participants had hearing thresholds <40 dB HL at 2 kHz and 70 dB HL at 4 kHz in at least one ear. Additionally, the median 2, 3, and 4 kHz pure tone threshold average (PTA2,3,4) for the sample, ∼17 dB HL, was used to delineate subgroups of better and worse hearing ears, and only the better hearing sample was modeled statistically. We modeled ABR responses using age, repetition rate, and PTA2,3,4 as covariates. Random effects were used to model correlation between the two ears of a subject and across repetition rates. Inferences regarding effects of aging on ABR measures at each rate were derived from the fitted model. Results were compared to data from subjects with poorer hearing. RESULTS Aging substantially diminished amplitudes of all of the principal ABR peaks, largely independent of any threshold differences within the group. For waves I and III, age-related amplitude decrements were greatest at a low (11/sec) click rate. At the 11/sec rate, the model-based mean wave III amplitude was significantly smaller in older compared with younger subjects even after adjusting for wave I amplitude. Aging also increased ABR peak latencies, with significant shifts limited to early waves. The I-V IPI did not change with age. For both younger and older subjects, increasing click presentation rate significantly decreased amplitudes of early peaks and prolonged latencies of later peaks, resulting in increased IPIs. Advanced age did not enhance effects of rate. Instead, the rate effect on wave I and III amplitudes was attenuated for the older subjects due to reduced peak amplitudes at lower click rates. Compared with model predictions from the sample of better hearing subjects, mean ABR amplitudes were diminished in the group with poorer hearing, and wave V latencies were prolonged. CONCLUSIONS In a sample of veterans, aging substantially reduced amplitudes of all principal ABR peaks, with significant latency shifts limited to waves I and III. Aging did not influence the I-V IPI even at high click rates, suggesting that the observed absolute latency changes associated with aging can be attributed to changes in auditory nerve input. In contrast, ABR amplitude changes with age are not adequately explained by changes in wave I. Results suggest that aging reduces the numbers and/or synchrony of contributing auditory nerve units. Results also support the concept that aging reduces the numbers, though perhaps not the synchrony, of central ABR generators.
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Affiliation(s)
- Dawn Konrad-Martin
- VA RR&D National Center for Rehabilitative Auditory Research, Portland VA Medical Center, Portland, OR 97239, USA.
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29
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Chen I, Limb CJ, Ryugo DK. The effect of cochlear-implant-mediated electrical stimulation on spiral ganglion cells in congenitally deaf white cats. J Assoc Res Otolaryngol 2010; 11:587-603. [PMID: 20821032 PMCID: PMC2975880 DOI: 10.1007/s10162-010-0234-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 08/13/2010] [Indexed: 10/19/2022] Open
Abstract
It has long been observed that loss of auditory receptor cells is associated with the progressive degeneration of spiral ganglion cells. Chronic electrical stimulation via cochlear implantation has been used in an attempt to slow the rate of degeneration in cats neonatally deafened by ototoxic agents but with mixed results. The present study examined this issue using white cats with a history of hereditary deafness as an alternative animal model. Nineteen cats provided new data for this study: four normal-hearing cats, seven congenitally deaf white cats, and eight congenitally deaf white cats with unilateral cochlear implants. Data from additional cats were collected from the literature. Electrical stimulation began at 3 to 4 or 6 to 7 months after birth, and cats received stimulation for approximately 7 h a day, 5 days a week for 12 weeks. Quantitative analysis of spiral ganglion cell counts, cell density, and cell body size showed no marked improvement between cochlear-implanted and congenitally deaf subjects. Average ganglion cell size from cochlear-implanted and congenitally deaf cats was statistically similar and smaller than that of normal-hearing cats. Cell density from cats with cochlear implants tended to decrease within the upper basal and middle cochlear turns in comparison to congenitally deaf cats but remained at congenitally deaf levels within the lower basal and apical cochlear turns. These results provide no evidence that chronic electrical stimulation enhances spiral ganglion cell survival, cell density, or cell size compared to that of unstimulated congenitally deaf cats. Regardless of ganglion neuron status, there is unambiguous restoration of auditory nerve synapses in the cochlear nucleus of these cats implanted at the earlier age.
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Affiliation(s)
- Iris Chen
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
| | - Charles J. Limb
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
| | - David K. Ryugo
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
- Department of Neuroscience, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010 Australia
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30
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Electrophysiological and morphological development of the inner ear in Belgian Waterslager canaries. Hear Res 2010; 269:56-69. [PMID: 20638464 DOI: 10.1016/j.heares.2010.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 06/23/2010] [Accepted: 07/08/2010] [Indexed: 01/11/2023]
Abstract
Belgian Waterslager (BW) canaries have an inherited hearing loss due to missing and abnormal hair cells, but it is unclear whether the loss is congenital or developmental. We used auditory brainstem responses and scanning electron microscopy to describe the development of auditory sensitivity and hair cell abnormalities in BW and non-BW canaries. In both strains, adult ABR thresholds were higher than behavioral thresholds, but BW canaries exhibited higher thresholds than non-BW canaries across all frequencies. Immediately post-hatch, ABR thresholds and hair cell numbers were similar in both strains. Two weeks later, thresholds were significantly higher in BW canaries, and hair cell number progressively decreased as the birds aged. These data show that in BW canaries: the peripheral auditory system is functionally similar to non-BW canary from hatch to 2 weeks, ABR thresholds improve during this developmental period, actually becoming better than those of adults, but then worsen as the bird continues to age. Hair cell number and appearance is similar to non-BW canaries at hatch but progressively declines after 30 days of age. These data show that the hearing loss characteristic of BW canaries is, at least in part, developmental and is established by the time song learning begins.
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31
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Knipper M, Zimmermann U, Müller M. Molecular aspects of tinnitus. Hear Res 2010; 266:60-9. [DOI: 10.1016/j.heares.2009.07.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 07/28/2009] [Accepted: 07/28/2009] [Indexed: 01/18/2023]
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32
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Kujawa SG, Liberman MC. Adding insult to injury: cochlear nerve degeneration after "temporary" noise-induced hearing loss. J Neurosci 2009; 29:14077-85. [PMID: 19906956 PMCID: PMC2812055 DOI: 10.1523/jneurosci.2845-09.2009] [Citation(s) in RCA: 1612] [Impact Index Per Article: 107.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 10/05/2009] [Accepted: 10/06/2009] [Indexed: 11/21/2022] Open
Abstract
Overexposure to intense sound can cause temporary or permanent hearing loss. Postexposure recovery of threshold sensitivity has been assumed to indicate reversal of damage to delicate mechano-sensory and neural structures of the inner ear and no persistent or delayed consequences for auditory function. Here, we show, using cochlear functional assays and confocal imaging of the inner ear in mouse, that acoustic overexposures causing moderate, but completely reversible, threshold elevation leave cochlear sensory cells intact, but cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve. Results suggest that noise-induced damage to the ear has progressive consequences that are considerably more widespread than are revealed by conventional threshold testing. This primary neurodegeneration should add to difficulties hearing in noisy environments, and could contribute to tinnitus, hyperacusis, and other perceptual anomalies commonly associated with inner ear damage.
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MESH Headings
- Acoustic Stimulation
- Animals
- Cell Death
- Cochlear Nerve/cytology
- Cochlear Nerve/pathology
- Cochlear Nerve/physiopathology
- Ear, Inner/cytology
- Ear, Inner/pathology
- Ear, Inner/physiopathology
- Ganglia, Sensory/cytology
- Ganglia, Sensory/pathology
- Ganglia, Sensory/physiopathology
- Hearing Loss, Noise-Induced/complications
- Hearing Loss, Noise-Induced/physiopathology
- Male
- Mice
- Mice, Inbred CBA
- Nerve Degeneration/etiology
- Nerve Degeneration/pathology
- Nerve Degeneration/physiopathology
- Neurons/cytology
- Neurons/pathology
- Neurons/physiology
- Neurons, Afferent/cytology
- Neurons, Afferent/pathology
- Neurons, Afferent/physiology
- Noise
- Otoacoustic Emissions, Spontaneous
- Synapses/pathology
- Synapses/physiology
- Vestibulocochlear Nerve Diseases/etiology
- Vestibulocochlear Nerve Diseases/physiopathology
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Affiliation(s)
- Sharon G Kujawa
- Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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El-Badry MM, McFadden SL. Evaluation of inner hair cell and nerve fiber loss as sufficient pathologies underlying auditory neuropathy. Hear Res 2009; 255:84-90. [PMID: 19531376 DOI: 10.1016/j.heares.2009.06.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 05/29/2009] [Accepted: 06/09/2009] [Indexed: 10/20/2022]
Abstract
Auditory neuropathy is a hearing disorder characterized by normal function of outer hair cells, evidenced by intact cochlear microphonic (CM) potentials and otoacoustic emissions (OAEs), with absent or severely dys-synchronized auditory brainstem responses (ABRs). To determine if selective lesions of inner hair cells (IHCs) and auditory nerve fibers (ANFs) can account for these primary clinical features of auditory neuropathy, we measured physiological responses from chinchillas with large lesions of ANFs (about 85%) and IHCs (45% loss in the apical half of the cochlea; 73% in the basal half). Distortion product OAEs and CM potentials were significantly enhanced, whereas summating potentials and compound action potentials (CAPs) were significantly reduced. CAP threshold was elevated by 7.5dB, but response synchrony was well preserved down to threshold levels of stimulation. Similarly, ABR threshold was elevated by 5.6dB, but all waves were present and well synchronized down to threshold levels in all animals. Thus, large lesions of IHCs and ANFs reduced response amplitudes but did not abolish or severely dys-synchronize CAPs or ABRs. Pathologies other than or in addition to ANF and IHC loss are likely to account for the evoked potential dys-synchrony that is a clinical hallmark of auditory neuropathy in humans.
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Affiliation(s)
- Mohamed M El-Badry
- Otolaryngology Department, Audiology Unit, El-Minia University Hospitals, El-Minia University, El-Minia, Egypt.
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34
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Neural and receptor cochlear potentials obtained by transtympanic electrocochleography in auditory neuropathy. Clin Neurophysiol 2008; 119:1028-41. [DOI: 10.1016/j.clinph.2008.01.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 01/16/2008] [Accepted: 01/26/2008] [Indexed: 11/22/2022]
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