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Noble K, Brown L, Elvis P, Lang H. Cochlear Immune Response in Presbyacusis: a Focus on Dysregulation of Macrophage Activity. J Assoc Res Otolaryngol 2022; 23:1-16. [PMID: 34642854 PMCID: PMC8782976 DOI: 10.1007/s10162-021-00819-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/25/2021] [Indexed: 02/03/2023] Open
Abstract
Age-related hearing loss, or presbyacusis, is a prominent chronic degenerative disorder that affects many older people. Based on presbyacusis pathology, the degeneration occurs in both sensory and non-sensory cells, along with changes in the cochlear microenvironment. The progression of age-related neurodegenerative diseases is associated with an altered microenvironment that reflects chronic inflammatory signaling. Under these conditions, resident and recruited immune cells, such as microglia/macrophages, have aberrant activity that contributes to chronic neuroinflammation and neural cell degeneration. Recently, researchers identified and characterized macrophages in human cochleae (including those from older donors). Along with the age-related changes in cochlear macrophages in animal models, these studies revealed that macrophages, an underappreciated group of immune cells, may play a critical role in maintaining the functional integrity of the cochlea. Although several studies deciphered the molecular mechanisms that regulate microglia/macrophage dysfunction in multiple neurodegenerative diseases, limited studies have assessed the mechanisms underlying macrophage dysfunction in aged cochleae. In this review, we highlight the age-related changes in cochlear macrophage activities in mouse and human temporal bones. We focus on how complement dysregulation and the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 inflammasome could affect macrophage activity in the aged peripheral auditory system. By understanding the molecular mechanisms that underlie these regulatory systems, we may uncover therapeutic strategies to treat presbyacusis and other forms of sensorineural hearing loss.
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Affiliation(s)
- Kenyaria Noble
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
- Akouos, Inc, Boston, MA, 02210, USA
| | - LaShardai Brown
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
- Department of Biology, Winthrop University, Rock Hill, SD, 29733, USA
| | - Phillip Elvis
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA.
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Li S, Cheng C, Lu L, Ma X, Zhang X, Li A, Chen J, Qian X, Gao X. Hearing Loss in Neurological Disorders. Front Cell Dev Biol 2021; 9:716300. [PMID: 34458270 PMCID: PMC8385440 DOI: 10.3389/fcell.2021.716300] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/23/2021] [Indexed: 12/11/2022] Open
Abstract
Sensorineural hearing loss (SNHL) affects approximately 466 million people worldwide, which is projected to reach 900 million by 2050. Its histological characteristics are lesions in cochlear hair cells, supporting cells, and auditory nerve endings. Neurological disorders cover a wide range of diseases affecting the nervous system, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), autism spectrum disorder (ASD), etc. Many studies have revealed that neurological disorders manifest with hearing loss, in addition to typical nervous symptoms. The prevalence, manifestations, and neuropathological mechanisms underlying vary among different diseases. In this review, we discuss the relevant literature, from clinical trials to research mice models, to provide an overview of auditory dysfunctions in the most common neurological disorders, particularly those associated with hearing loss, and to explain their underlying pathological and molecular mechanisms.
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Affiliation(s)
- Siyu Li
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Cheng Cheng
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Ling Lu
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Xiaofeng Ma
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
| | - Xiaoli Zhang
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Ao Li
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Jie Chen
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Xiaoyun Qian
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Xia Gao
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
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Eckert MA, Harris KC, Lang H, Lewis MA, Schmiedt RA, Schulte BA, Steel KP, Vaden KI, Dubno JR. Translational and interdisciplinary insights into presbyacusis: A multidimensional disease. Hear Res 2021; 402:108109. [PMID: 33189490 PMCID: PMC7927149 DOI: 10.1016/j.heares.2020.108109] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 10/19/2020] [Accepted: 10/25/2020] [Indexed: 12/18/2022]
Abstract
There are multiple etiologies and phenotypes of age-related hearing loss or presbyacusis. In this review we summarize findings from animal and human studies of presbyacusis, including those that provide the theoretical framework for distinct metabolic, sensory, and neural presbyacusis phenotypes. A key finding in quiet-aged animals is a decline in the endocochlear potential (EP) that results in elevated pure-tone thresholds across frequencies with greater losses at higher frequencies. In contrast, sensory presbyacusis appears to derive, in part, from acute and cumulative effects on hair cells of a lifetime of environmental exposures (e.g., noise), which often result in pronounced high frequency hearing loss. These patterns of hearing loss in animals are recognizable in the human audiogram and can be classified into metabolic and sensory presbyacusis phenotypes, as well as a mixed metabolic+sensory phenotype. However, the audiogram does not fully characterize age-related changes in auditory function. Along with the effects of peripheral auditory system declines on the auditory nerve, primary degeneration in the spiral ganglion also appears to contribute to central auditory system aging. These inner ear alterations often correlate with structural and functional changes throughout the central nervous system and may explain suprathreshold speech communication difficulties in older adults with hearing loss. Throughout this review we highlight potential methods and research directions, with the goal of advancing our understanding, prevention, diagnosis, and treatment of presbyacusis.
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Affiliation(s)
- Mark A Eckert
- Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA.
| | - Kelly C Harris
- Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA
| | - Hainan Lang
- Medical University of South Carolina, Department of Pathology and Laboratory Medicine, Charleston, SC 29425, USA
| | - Morag A Lewis
- King's College London, Wolfson Centre for Age-Related Diseases, London SE1 1UL, United Kingdom
| | - Richard A Schmiedt
- Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA
| | - Bradley A Schulte
- Medical University of South Carolina, Department of Pathology and Laboratory Medicine, Charleston, SC 29425, USA; Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA
| | - Karen P Steel
- King's College London, Wolfson Centre for Age-Related Diseases, London SE1 1UL, United Kingdom
| | - Kenneth I Vaden
- Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA
| | - Judy R Dubno
- Medical University of South Carolina, Department of Otolaryngology - Head and Neck Surgery, Charleston, SC 29425, USA; Medical University of South Carolina, Department of Pathology and Laboratory Medicine, Charleston, SC 29425, USA
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Noble KV, Liu T, Matthews LJ, Schulte BA, Lang H. Age-Related Changes in Immune Cells of the Human Cochlea. Front Neurol 2019; 10:895. [PMID: 31474935 PMCID: PMC6707808 DOI: 10.3389/fneur.2019.00895] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 08/02/2019] [Indexed: 12/12/2022] Open
Abstract
Age-related hearing loss is a chronic degenerative disorder affecting one in two individuals above the age of 75. Current population projections predict a steady climb in the number of older individuals making the search for interventions to prevent or reverse this disorder even more critical. There is growing acceptance that aberrant activity of resident or infiltrating immune cells, such as macrophages, is a major factor contributing to the onset and progression of age-related degenerative diseases. However, how macrophage populations and their functionally-driven morphological characteristics change with age in the human cochlea remains largely unknown. In this study, we employed immunohistochemical approaches along with confocal and super-resolution imaging, three-dimensional reconstructions, and quantitative analysis to determine age-related changes in macrophage numbers and morphology as well as interactions with other cell-types and structures of the auditory nerve and lateral wall in the human cochlea. In the cochlea of human ears from young and middle aged adults those macrophages in the auditory nerve assumed a worm-like structure in contrast to those in the spiral ligament or associated with the dense microvascular network in the stria vascularis which exhibited a highly ramified morphology. Macrophages in both the auditory nerve and cochlear lateral wall showed morphological alterations with age. The population of activated macrophages in the auditory nerve increased in cochleas obtained from older donors. Dual-immunohistochemical staining with macrophage, myelin, and neuronal markers revealed increased interactions of macrophages with the glial and neuronal components of the aged auditory nerve. These findings implicate the involvement of abnormal macrophage-glia interactions in age-related physiological and pathological alterations in the human cochlea. There is clearly a need to further investigate the contribution of macrophage-associated inflammatory dysregulation in human presbyacusis.
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Affiliation(s)
- Kenyaria V. Noble
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Ting Liu
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Lois J. Matthews
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, United States
| | - Bradley A. Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, United States
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
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Ding B, Walton JP, Zhu X, Frisina RD. Age-related changes in Na, K-ATPase expression, subunit isoform selection and assembly in the stria vascularis lateral wall of mouse cochlea. Hear Res 2018; 367:59-73. [PMID: 30029086 DOI: 10.1016/j.heares.2018.07.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 07/02/2018] [Accepted: 07/06/2018] [Indexed: 11/26/2022]
Abstract
Due to the critical role of cochlear ion channels for hearing, the focus of the present study was to examine age-related changes of Na, K-ATPase (NKA) subunits in the lateral wall of mouse cochlea. We combined qRT-PCR, western blot and immunocytochemistry methodologies in order to determine gene and protein expression levels in the lateral wall of young and aged CBA/CaJ mice. Of the seven NKA subunits, only the mRNA expressions of α1, β1 and β2 subunit isoforms were detected in the lateral wall of CBA/CaJ mice. Aging was accompanied by dys-regulation of gene and protein expression of all three subunits detected. Hematoxylin and eosin (H&E) staining revealed atrophy of the cochlear stria vascularis (SV). The SV atrophy rate (20%) was much less than the ∼80% decline in expression of all three NKA isoforms, indicating lateral wall atrophy and NKA dys-regulation are independent factors and that there is a combination of changes involving the morphology of SV and NKA expression in the aging cochlea which may concomitantly affect cochlear function. Immunoprecipitation assays showed that the α1-β1 heterodimer is the selective preferential heterodimer over the α1-β2 heterodimer in cochlea lateral wall. Interestingly, in vitro pathway experiments utilizing cultured mouse cochlear marginal cells from the SV (SV-K1 cells) indicated that decreased mRNA and protein expressions of α1, β1 and β2 subunit isoforms are not associated with reduction of NKA activity following in vitro application of ouabain, but ouabain did disrupt the α1-β1 heterodimer interaction. Lastly, the association between the α1 and β1 subunit isoforms was present in the cochlear lateral wall of young adult mice, but this interaction could not be detected in old mice. Taken together, these data suggest that in the young adult mouse there is a specific, functional selection and assembly of NKA subunit isoforms in the SV lateral wall, which is disrupted and dys-regulated with age. Interventions for this age-linked ion channel disruption may have the potential to help diagnose, prevent, or treat age-related hearing loss.
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Affiliation(s)
- Bo Ding
- Dept. Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - Joseph P Walton
- Dept. Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA.
| | - Xiaoxia Zhu
- Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - Robert D Frisina
- Dept. Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
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Lang H, Nishimoto E, Xing Y, Brown LN, Noble KV, Barth JL, LaRue AC, Ando K, Schulte BA. Contributions of Mouse and Human Hematopoietic Cells to Remodeling of the Adult Auditory Nerve After Neuron Loss. Mol Ther 2016; 24:2000-2011. [PMID: 27600399 PMCID: PMC5154482 DOI: 10.1038/mt.2016.174] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/25/2016] [Indexed: 12/20/2022] Open
Abstract
The peripheral auditory nerve (AN) carries sound information from sensory hair cells to the brain. The present study investigated the contribution of mouse and human hematopoietic stem cells (HSCs) to cellular diversity in the AN following the destruction of neuron cell bodies, also known as spiral ganglion neurons (SGNs). Exposure of the adult mouse cochlea to ouabain selectively killed type I SGNs and disrupted the blood-labyrinth barrier. This procedure also resulted in the upregulation of genes associated with hematopoietic cell homing and differentiation, and provided an environment conducive to the tissue engraftment of circulating stem/progenitor cells into the AN. Experiments were performed using both a mouse-mouse bone marrow transplantation model and a severely immune-incompetent mouse model transplanted with human CD34+ cord blood cells. Quantitative immunohistochemical analysis of recipient mice demonstrated that ouabain injury promoted an increase in the number of both HSC-derived macrophages and HSC-derived nonmacrophages in the AN. Although rare, a few HSC-derived cells in the injured AN exhibited glial-like qualities. These results suggest that human hematopoietic cells participate in remodeling of the AN after neuron cell body loss and that hematopoietic cells can be an important resource for promoting AN repair/regeneration in the adult inner ear.
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Affiliation(s)
- Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.
| | - Eishi Nishimoto
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Yazhi Xing
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - LaShardai N Brown
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Kenyaria V Noble
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jeremy L Barth
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Amanda C LaRue
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA; Research Services, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, South Carolina, USA
| | - Kiyoshi Ando
- Research Center for Regenerative Medicine, Division of Hematopoiesis, Tokai University School of Medicine, Tokyo, Japan
| | - Bradley A Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
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Gleich O, Semmler P, Strutz J. Behavioral auditory thresholds and loss of ribbon synapses at inner hair cells in aged gerbils. Exp Gerontol 2016; 84:61-70. [PMID: 27569111 DOI: 10.1016/j.exger.2016.08.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/29/2016] [Accepted: 08/24/2016] [Indexed: 11/27/2022]
Abstract
The potential contribution of auditory synaptopathy to age dependent hearing loss was studied in groups of young and old gerbils. The analysis of the number of inner hair cell ribbon synapses in aged gerbils (37.9±3.3months of age) revealed only a relatively small (11-17%) loss in the basal two thirds of the cochlea, while a more pronounced reduction was identified towards the apex (almost 40%) when compared to a group of young gerbils (9.5±3.2months of age). Mean threshold elevation in the old gerbils was around 25dB at 2 and 10kHz. Frequency-specific behavioral thresholds and ribbon synapse counts were not significantly correlated for the middle and basal regions of the cochlea, despite thresholds varying over a 45dB SPL range. This suggests that besides a small age-dependent loss of ribbon synapses, additional cochlear pathologies, most likely a decreased endocochlear potential, contribute to peripheral hearing loss in old gerbils.
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Affiliation(s)
- Otto Gleich
- ENT-Department University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.
| | - Philipp Semmler
- ENT-Department University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Jürgen Strutz
- ENT-Department University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
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Zucker diabetic fatty rats, a model for type 2 diabetes, develop an inner ear dysfunction that can be attenuated by losartan treatment. Cell Tissue Res 2015; 362:307-15. [DOI: 10.1007/s00441-015-2215-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/12/2015] [Indexed: 12/13/2022]
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Hao X, Xing Y, Moore MW, Zhang J, Han D, Schulte BA, Dubno JR, Lang H. Sox10 expressing cells in the lateral wall of the aged mouse and human cochlea. PLoS One 2014; 9:e97389. [PMID: 24887110 PMCID: PMC4041576 DOI: 10.1371/journal.pone.0097389] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/17/2014] [Indexed: 12/20/2022] Open
Abstract
Age-related hearing loss (presbycusis) is a common human disorder, affecting one in three Americans aged 60 and over. Previous studies have shown that presbyacusis is associated with a loss of non-sensory cells in the cochlear lateral wall. Sox10 is a transcription factor crucial to the development and maintenance of neural crest-derived cells including some non-sensory cell types in the cochlea. Mutations of the Sox10 gene are known to cause various combinations of hearing loss and pigmentation defects in humans. This study investigated the potential relationship between Sox10 gene expression and pathological changes in the cochlear lateral wall of aged CBA/CaJ mice and human temporal bones from older donors. Cochlear tissues prepared from young adult (1–3 month-old) and aged (2–2.5 year-old) mice, and human temporal bone donors were examined using quantitative immunohistochemical analysis and transmission electron microscopy. Cells expressing Sox10 were present in the stria vascularis, outer sulcus and spiral prominence in mouse and human cochleas. The Sox10+ cell types included marginal and intermediate cells and outer sulcus cells, including those that border the scala media and those extending into root processes (root cells) in the spiral ligament. Quantitative analysis of immunostaining revealed a significant decrease in the number of Sox10+ marginal cells and outer sulcus cells in aged mice. Electron microscopic evaluation revealed degenerative alterations in the surviving Sox10+ cells in aged mice. Strial marginal cells in human cochleas from donors aged 87 and older showed only weak immunostaining for Sox10. Decreases in Sox10 expression levels and a loss of Sox10+ cells in both mouse and human aged ears suggests an important role of Sox10 in the maintenance of structural and functional integrity of the lateral wall. A loss of Sox10+ cells may also be associated with a decline in the repair capabilities of non-sensory cells in the aged ear.
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Affiliation(s)
- Xinping Hao
- Department of Otolaryngology – Head & Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Yazhi Xing
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Michael W. Moore
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Jianning Zhang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology, Shanghai Yueyang Integrated Medicine Hospital, Shanghai, China
| | - Demin Han
- Department of Otolaryngology – Head & Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- * E-mail: (HL); (DH)
| | - Bradley A. Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Judy R. Dubno
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail: (HL); (DH)
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Mann ZF, Chang W, Lee KY, King KA, Kelley MW. Expression and function of scleraxis in the developing auditory system. PLoS One 2013; 8:e75521. [PMID: 24058692 PMCID: PMC3772897 DOI: 10.1371/journal.pone.0075521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 08/16/2013] [Indexed: 01/02/2023] Open
Abstract
A study of genes expressed in the developing inner ear identified the bHLH transcription factor Scleraxis (Scx) in the developing cochlea. Previous work has demonstrated an essential role for Scx in the differentiation and development of tendons, ligaments and cells of chondrogenic lineage. Expression in the cochlea has been shown previously, however the functional role for Scx in the cochlea is unknown. Using a Scx-GFP reporter mouse line we examined the spatial and temporal patterns of Scx expression in the developing cochlea between embryonic day 13.5 and postnatal day 25. Embryonically, Scx is expressed broadly throughout the cochlear duct and surrounding mesenchyme and at postnatal ages becomes restricted to the inner hair cells and the interdental cells of the spiral limbus. Deletion of Scx results in hearing impairment indicated by elevated auditory brainstem response (ABR) thresholds and diminished distortion product otoacoustic emission (DPOAE) amplitudes, across a range of frequencies. No changes in either gross cochlear morphology or expression of the Scx target genes Col2A, Bmp4 or Sox9 were observed in Scx(-/-) mutants, suggesting that the auditory defects observed in these animals may be a result of unidentified Scx-dependent processes within the cochlea.
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Affiliation(s)
- Zoe F. Mann
- Laboratory of Cochlear Development, NIDCD, NIH, Bethesda, Maryland, United States of America
- * E-mail:
| | - Weise Chang
- Laboratory of Cochlear Development, NIDCD, NIH, Bethesda, Maryland, United States of America
| | - Kyu Yup Lee
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Rockville, Maryland, United States of America
| | - Kelly A. King
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Matthew W. Kelley
- Laboratory of Cochlear Development, NIDCD, NIH, Bethesda, Maryland, United States of America
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Frisina RD, Zhu X. Auditory sensitivity and the outer hair cell system in the CBA mouse model of age-related hearing loss. ACTA ACUST UNITED AC 2010; 2:9-16. [PMID: 21866215 DOI: 10.2147/oaap.s7202] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Age-related hearing loss is a highly prevalent sensory disorder, from both the clinical and animal model perspectives. Understanding of the neurophysiologic, structural, and molecular biologic bases of age-related hearing loss will facilitate development of biomedical therapeutic interventions to prevent, slow, or reverse its progression. Thus, increased understanding of relationships between aging of the cochlear (auditory portion of the inner ear) hair cell system and decline in overall hearing ability is necessary. The goal of the present investigation was to test the hypothesis that there would be correlations between physiologic measures of outer hair cell function (otoacoustic emission levels) and hearing sensitivity (auditory brainstem response thresholds), starting in middle age. For the CBA mouse, a useful animal model of age-related hearing loss, it was found that correlations between these two hearing measures occurred only for high sound frequencies in middle age. However, in old age, a correlation was observed across the entire mouse range of hearing. These findings have implications for improved early detection of progression of age-related hearing loss in middle-aged mammals, including mice and humans, and distinguishing peripheral etiologies from central auditory system decline.
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Affiliation(s)
- Robert D Frisina
- Otolaryngology, Biomedical Engineering, Neurobiology, and Anatomy Departments, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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12
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Chronic reduction of endocochlear potential reduces auditory nerve activity: further confirmation of an animal model of metabolic presbyacusis. J Assoc Res Otolaryngol 2010; 11:419-34. [PMID: 20372958 DOI: 10.1007/s10162-010-0214-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 03/08/2010] [Indexed: 02/06/2023] Open
Abstract
Gerbils aged in quiet show a decline of the endocochlear potential (EP) and elevated auditory nerve compound action potential (CAP) thresholds. However, establishing a direct relationship between an age-related reduction in the EP and changes in the activities of primary auditory neurons is difficult owing to the complexity of age-related histological changes in the cochlea. To address this issue, we developed a young gerbil model of "metabolic" presbyacusis that uses an osmotic pump to deliver furosemide into the round window niche for 7 days, resulting in a chronically reduced EP. In this model, the only major histopathologic changes were restricted to the hook region of the cochlea and consisted of loss of strial intermediate cells and massive edema in the lateral wall. The morphological and physiological evidence suggests that the cochlea can adapt to furosemide application over time. The morphology of spiral ganglion cells and hair cells appeared normal throughout the cochlea. CAP responses and EP values in this model are similar to those of quiet-aged ears. The spontaneous activity of single auditory fibers (n = 188) was assessed in 15 young gerbils treated with furosemide for 7 days. The percentage of recorded low-spontaneous rate (SR) fibers at characteristic frequencies (CFs) > or = 6 kHz was significantly lower in furosemide-treated than in control ears. Recovery function tests of CAP responses after prior stimulation also showed a decline in activity of the low-SR population with CFs > or = 6 kHz in the treated cochleas. A similar loss in the activity of low-SR fiber has been previously shown in quiet-aged gerbils. These results suggest that dysfunction of the cochlear lateral wall and subsequent chronic reduction in the EP can directly affect the activity patterns of primary auditory neurons in a manner similar to that seen in aged gerbils.
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Pratt SR, Kuller L, Talbott EO, McHugh-Pemu K, Buhari AM, Xu X. Prevalence of hearing loss in Black and White elders: results of the Cardiovascular Health Study. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2009; 52:973-89. [PMID: 19380605 PMCID: PMC2719023 DOI: 10.1044/1092-4388(2009/08-0026)] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
PURPOSE The goal of this study was to determine the impact of age, gender, and race on the prevalence and severity of hearing loss in elder adults, aged 72-96 years, after accounting for income, education, smoking, and clinical and subclinical cardiovascular disease. Methods Air-conduction thresholds for standard and extended high-frequency pure-tones were obtained from a cohort of 548 (out of 717) elderly adults (ages 72-96 years) who were recruited during the Year 11 clinical visit (1999-2000) of the Cardiovascular Health Study (CHS) at the Pittsburgh, Pennsylvania site. Participant smoking, income, education, and cardiovascular disease histories were obtained from the CHS database and were included as factors. RESULTS Hearing loss was more common and more severe for the participants in their 80s than for those in their 70s-the men more than the women and the White participants more than the Black participants. The inclusion of education, income, smoking, and cardiovascular disease (clinical and subclinical) histories as factors did not substantively impact the overall results. CONCLUSION Although the data reported in this article were cross-sectional and a cohort phenomenon might have been operational, they suggested that hearing loss is more substantive in the 8th than the 7th decade of life and that race and gender influence this decline in audition. Given the high prevalence in the aging population and the differences across groups, there is a clear need to understand the nature and causes of hearing loss across various groups in order to improve prevention and develop appropriate interventions.
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Affiliation(s)
- Sheila R Pratt
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Intervención de los fibrocitos del ligamento espiral en la regulación metabólica del oído interno. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2008. [DOI: 10.1016/s0001-6519(08)75519-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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16
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Méndez-Benegassi I, Trinidad A, García-Berrocal JR, Martín C, Martínez-Monedero R, Verdaguer JM, Ramírez-Camacho R. Estudio ultraestructural de la porción lateral del órgano sensorial auditivo mediante un método sin descalcificación. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2008. [DOI: 10.1016/s0001-6519(08)75985-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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17
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García Berrocal JR, Méndez-Benegassi I, Martín C, Ramírez Camacho R. Intervention of Spiral Ligament Fibrocytes in the Metabolic Regulation of the Inner Ear. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2008. [DOI: 10.1016/s2173-5735(08)70281-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ultra-Structural Study of the Lateral Portion of the Auditory Sensorial Organ Using a Decalcification-Free Method. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2008. [DOI: 10.1016/s2173-5735(08)70258-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Diaz RC, Vazquez AE, Dou H, Wei D, Cardell EL, Lingrel J, Shull GE, Doyle KJ, Yamoah EN. Conservation of hearing by simultaneous mutation of Na,K-ATPase and NKCC1. J Assoc Res Otolaryngol 2007; 8:422-34. [PMID: 17674100 PMCID: PMC2538340 DOI: 10.1007/s10162-007-0089-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 06/21/2007] [Indexed: 12/13/2022] Open
Abstract
Although drug-induced and age-related hearing losses are frequent otologic problems affecting millions of people, their underlying mechanisms remain uncertain. The inner ear is exclusively endowed with a positive endocochlear potential (EP) that serves as the main driving force for the generation of receptor potential in hair cells to confer hearing. Deterioration of EP leads to hearing loss or deafness. The generation of EP relies on the activity of many ion transporters to establish active potassium (K(+)) cycling within the inner ear, including K(+) channels, the Na-K-2Cl co-transporter (NKCC1), and the alpha(1) and alpha(2) isoforms of Na,K-ATPase. We show that heterozygous deletion of either NKCC1, alpha(1)-Na,K-ATPase, or alpha(2)-Na,K-ATPase independently results in progressive, age-dependent hearing loss with minimal alteration in cochlear morphology. Double heterozygote deletion of NKCC1 with alpha(1)-Na,K-ATPase also shows a progressive, though delayed, age-dependent hearing loss. Remarkably, double heterozygote deletion of NKCC1 with alpha(2)-Na,K-ATPase demonstrates a striking preservation of hearing threshold both initially and with age. Measurements of the EP confirm the anticipated drop in potential for genotypes that demonstrate age-dependent hearing loss. The EP generated by the NKCC1 + alpha(2)-Na,K-ATPase double heterozygote, however, is maintained at a level comparable to that of the control condition, suggesting a potential advantage in this combination of ion transporter modification. These observations provide insight into the detailed mechanisms of EP generation, and results of combination-knockout experiments may have important implications in the future treatment of drug-induced and age-related hearing losses.
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Affiliation(s)
- Rodney C Diaz
- Department of Otolaryngology-Head and Neck Surgery, University of California Davis School of Medicine, 1515 Newton Court, Davis, CA 95618, USA.
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Ishiyama G, Tokita J, Lopez I, Tang Y, Ishiyama A. Unbiased stereological estimation of the spiral ligament and stria vascularis volumes in aging and Ménière's disease using archival human temporal bones. J Assoc Res Otolaryngol 2007; 8:8-17. [PMID: 17160359 PMCID: PMC2538411 DOI: 10.1007/s10162-006-0057-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 09/06/2006] [Accepted: 10/01/2006] [Indexed: 11/26/2022] Open
Abstract
The present study applies the unbiased stereological technique-Cavalieri principle to measure the volumes of the stria vascularis (SV) and the spiral ligament (SL) using postmortem archival human temporal bones from normal young and older subjects and subjects with Ménière's disease. Normative data was obtained from subjects without ages ranging from 15 to 84 years old who had no history of audiovestibular disease (N=25). For comparison purposes, the normative specimens were divided into three groups: group 1 (n=8) had ages ranging from 15 to 38 years old, average age=23.9; group 2 (n=8) had ages ranging from 51 to 59 years old, average age=55.1; group 3 (n=9) had ages ranging from 64 to 84 years old, average age=74.3. The average SV volume of group 3 (0.479 mm3) was significantly lower than that of group 1 (0.705 mm3) (p<0.0005) and was significantly lower than that of group 2 (0.603 mm3) (p=0.01). The average SL volume of group 3 (8.42 mm3) was significantly lower than that of group 1 (9.54 mm3) (p<0.05), but was not significantly lower than that of group 2 (8.58 mm3). Five subjects with Ménière's disease, confirmed by histopathological examination (ages ranging from 63 to 91 years old, average age=73.4), were studied. The average SV volume in Ménière's subjects (0.378 mm3) was significantly lower than age-matched controls (p<0.05). The average SL volume in Ménière's subjects (7.01 mm3) was also significantly lower than age-matched controls (p<0.05). The SV and SL volumes were unaffected by gender. The present study demonstrates for the first time the use of the unbiased stereological technique-Cavalieri principle-as a reliable and efficient method to obtain volumetric estimates of the SV and the SL by using archival human temporal bone specimens.
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Affiliation(s)
- Gail Ishiyama
- Neurology Department, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA.
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Lang H, Ebihara Y, Schmiedt RA, Minamiguchi H, Zhou D, Smythe N, Liu L, Ogawa M, Schulte BA. Contribution of bone marrow hematopoietic stem cells to adult mouse inner ear: mesenchymal cells and fibrocytes. J Comp Neurol 2006; 496:187-201. [PMID: 16538683 PMCID: PMC2561311 DOI: 10.1002/cne.20929] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Bone marrow (BM)-derived stem cells have shown plasticity with a capacity to differentiate into a variety of specialized cells. To test the hypothesis that some cells in the inner ear are derived from BM, we transplanted either isolated whole BM cells or clonally expanded hematopoietic stem cells (HSCs) prepared from transgenic mice expressing enhanced green fluorescent protein (EGFP) into irradiated adult mice. Isolated GFP(+) BM cells were also transplanted into conditioned newborn mice derived from pregnant mice injected with busulfan (which ablates HSCs in the newborns). Quantification of GFP(+) cells was performed 3-20 months after transplant. GFP(+) cells were found in the inner ear with all transplant conditions. They were most abundant within the spiral ligament but were also found in other locations normally occupied by fibrocytes and mesenchymal cells. No GFP(+) neurons or hair cells were observed in inner ears of transplanted mice. Dual immunofluorescence assays demonstrated that most of the GFP(+) cells were negative for CD45, a macrophage and hematopoietic cell marker. A portion of the GFP(+) cells in the spiral ligament expressed immunoreactive Na, K-ATPase, or the Na-K-Cl transporter (NKCC), proteins used as markers for specialized ion transport fibrocytes. Phenotypic studies indicated that the GFP(+) cells did not arise from fusion of donor cells with endogenous cells. This study provides the first evidence for the origin of inner ear cells from BM and more specifically from HSCs. The results suggest that mesenchymal cells, including fibrocytes in the adult inner ear, may be derived continuously from HSCs.
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Affiliation(s)
- Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Spicer SS, Schulte BA. Pathologic changes of presbycusis begin in secondary processes and spread to primary processes of strial marginal cells. Hear Res 2006; 205:225-40. [PMID: 15953531 DOI: 10.1016/j.heares.2005.03.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 03/23/2005] [Indexed: 11/29/2022]
Abstract
Strial atrophy underlying age-related hearing loss was investigated by ultrastructural comparisons in young and senescent gerbils. In young animals strial marginal cells (MCs) projected primary processes which gave rise to and were connected by numerous ultrathin secondary processes. In 30-36-month-old gerbils, the MC secondary processes degenerated into lamellar or amorphous profiles as the first manifestation of strial atrophy. Some short primary processes shorn of projecting and connecting secondaries coalesced to form mitochondria-filled lobules. Strial involution appeared to progress with transformation of the degenerating processes and lobules into permanent residues of laminated amorphous substance. A second apparently unique form of degeneration was observed in which areas filled with homogeneous granular material replaced the processes that comprise the basal half of the normal MC. An abrupt line of transition separated this structureless degradation product below from the viable upper half of the MC. The terminally involuted stria consisted of MC bodies lining scala media, along with vestigial remnants of MC processes, nearby normal appearing intermediate cells (ICs) and unaltered basal cells. The only age-related change in ICs involved incorporation of melanosomes into very large, matrix-filled lysosomes. A profile of one MC in apparent necrosis provided evidence for an infrequent occurrence of MC death. These data support a progression of pathologic changes beginning with the demise of MC secondary processes and ending with ablation of secondary and primary processes. The initial injury apparently occurs as a result of oxidative self-damage to mitochondria in the MCs primary processes, leading to insufficient ATP for the Na,K-ATPase of the secondary processes. The reduced ATP level may cause cytotoxic alteration of the cytosolic Na(+)/K(+) ratio first in MC secondary processes and later in the primaries, with consequent degeneration of these structures.
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Affiliation(s)
- Samuel S Spicer
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
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Teufert KB, Linthicum F. Paget disease and sensorineural hearing loss associated with spiral ligament degeneration. Otol Neurotol 2005; 26:387-91; discussion 391. [PMID: 15891639 DOI: 10.1097/01.mao.0000169773.23668.3f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Previously unreported cystic degeneration of the spiral ligament in cases of Paget disease. BACKGROUND About 70% of cases of Paget disease involve the skull, with hearing affected in approximately 50% of these. The hearing impairment may be sensorineural, mixed, or, rarely, only conductive. The etiology and pathogenesis of the hearing loss are not yet understood, and reports in the literature are inconsistent regarding the pathologic changes responsible for sensorineural hearing loss. Of six pairs of temporal bones from patients with Paget disease in the temporal bone collection of a research institution, two pairs have abnormalities not previously associated with sensorineural hearing loss or Paget disease. We report the histopathologic findings in these temporal bones. METHODS The temporal bones were fixed in formalin, decalcified in ethylenediaminetetraacetic acid, embedded in celloidin, and sectioned in the horizontal plane at a thickness of 20 microm. Every 10th section was stained with hematoxylin-eosin and mounted on glass slides. The sections were examined by light microscopy. RESULTS Cystic degeneration of the spiral ligament, primarily in the basal segment, was found in both cases. Endolymphatic hydrops and a small endolymphatic sac with calcification of the perisaccular tissue were found in one case. CONCLUSIONS Cystic degeneration of the spiral ligament has not been previously reported and may be unique to Paget disease. This is consistent with recent literature showing a previously unsuspected role of the spiral ligament in sensorineural hearing loss.
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Affiliation(s)
- Karen Borne Teufert
- Histopathology Department, House Ear Institute, Los Angeles, California 90057, USA.
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Morris KA, Snir E, Pompeia C, Koroleva IV, Kachar B, Hayashizaki Y, Carninci P, Soares MB, Beisel KW. Differential expression of genes within the cochlea as defined by a custom mouse inner ear microarray. J Assoc Res Otolaryngol 2005; 6:75-89. [PMID: 15735932 PMCID: PMC2504641 DOI: 10.1007/s10162-004-5046-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 11/19/2004] [Indexed: 11/24/2022] Open
Abstract
Microarray analyses have contributed greatly to the rapid understanding of functional genomics through the identification of gene networks as well as gene discovery. To facilitate functional genomics of the inner ear, we have developed a mouse inner-ear-pertinent custom microarray chip (CMA-IE1). Nonredundant cDNA clones were obtained from two cDNA library resources: the RIKEN subtracted inner ear set and the NIH organ of Corti library. At least 2000 cDNAs unique to the inner ear were present on the chip. Comparisons were performed to examine the relative expression levels of these unique cDNAs within the organ of Corti, lateral wall, and spiral ganglion. Total RNA samples were obtained from the three cochlear-dissected fractions from adult CF-1 mice. The total RNA was linearly amplified, and a dendrimer-based system was utilized to enhance the hybridization signal. Differentially expressed genes were verified by comparison to known gene expression patterns in the cochlea or by correlation with genes and gene families deduced to be present in the three tissue types. Approximately 22-25% of the genes on the array had significant levels of expression. A number of differentially expressed genes were detected in each tissue fraction. These included genes with known functional roles, hypothetical genes, and various unknown or uncharacterized genes. Four of the differentially expressed genes found in the organ of Corti are linked to deafness loci. None of these are hypothetical or unknown genes.
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Affiliation(s)
- Ken A. Morris
- Department of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha, NE 68178 USA
| | - Einat Snir
- Pediatrics-Genetics, Iowa University, Iowa, IA 52242 USA
| | - Celine Pompeia
- Section on Structural Cell Biology, NIDCD/NIH, Bethesda, MD 20892 USA
| | | | - Bechara Kachar
- Section on Structural Cell Biology, NIDCD/NIH, Bethesda, MD 20892 USA
| | - Yoshihide Hayashizaki
- Laboratory for Genome Exploration Research Group, RIKEN Genomic Sciences Center, Tsukuba, Japan
| | - Piero Carninci
- Laboratory for Genome Exploration Research Group, RIKEN Genomic Sciences Center, Tsukuba, Japan
| | | | - Kirk W. Beisel
- Department of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha, NE 68178 USA
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Delprat B, Ruel J, Guitton MJ, Hamard G, Lenoir M, Pujol R, Puel JL, Brabet P, Hamel CP. Deafness and cochlear fibrocyte alterations in mice deficient for the inner ear protein otospiralin. Mol Cell Biol 2005; 25:847-53. [PMID: 15632083 PMCID: PMC543414 DOI: 10.1128/mcb.25.2.847-853.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the cochlea, the mammalian auditory organ, fibrocytes of the mesenchymal nonsensory regions play important roles in cochlear physiology, including the maintenance of ionic and hydric components in the endolymph. Occurrence of human deafness in fibrocyte alterations underlines their critical roles in auditory function. We recently described a novel gene, Otos, which encodes otospiralin, a small protein of unknown function that is produced by the fibrocytes of the cochlea and vestibule. We now have generated mice with deletion of Otos and found that they show moderate deafness, with no frequency predominance. Histopathology revealed a degeneration of type II and IV fibrocytes, while hair cells and stria vascularis appeared normal. Together, these findings suggest that impairment of fibrocytes caused by the loss in otospiralin leads to abnormal cochlear physiology and auditory function. This moderate dysfunction may predispose to age-related hearing loss.
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Affiliation(s)
- Benjamin Delprat
- INSERM U.583, Physiopathologie et Thérapie des Déficits Sensoriels et Moteurs, Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, BP 74103, 80, rue Augustin Fliche, 34295 Montpellier cedex 05, France.
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Kusunoki T, Cureoglu S, Schachern PA, Baba K, Kariya S, Paparella MM. Age-related histopathologic changes in the human cochlea: a temporal bone study. Otolaryngol Head Neck Surg 2005; 131:897-903. [PMID: 15577787 DOI: 10.1016/j.otohns.2004.05.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES Previous reports on aging of human cochlea included subjects with ear diseases or ototoxic drugs. We studied spiral ganglion cells, hair cells, and lateral wall of cochlea from subjects without ear disease or ototoxic drugs. STUDY DESIGN This study included 39 temporal bones from 24 subjects aged 1 day to 86 years. We assessed standard cytocochleograms, mean loss of fibrocytes in spiral ligament, and areas of stria vascularis. RESULTS Losses of outer hair cells and fibrocytes were significantly greater in children, adults, and the elderly compared with infants. Spiral ganglion cell loss was significantly greater in adults and elderly compared with infants and children. Areas of stria vascularis of infants were significantly larger than the elderly. CONCLUSIONS Degenerative changes of outer hair cells occur in children but spiral ganglion cells remain the same until around 20 years. Degeneration of stria vascularis due to aging appears to be slower than spiral ligament. EBM RATING C.
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Resendes BL, Kuo SF, Robertson NG, Giersch ABS, Honrubia D, Ohara O, Adams JC, Morton CC. Isolation from cochlea of a novel human intronless gene with predominant fetal expression. J Assoc Res Otolaryngol 2004; 5:185-202. [PMID: 15357420 PMCID: PMC2538407 DOI: 10.1007/s10162-003-4042-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
We have cloned a novel human gene, designated PFET1 (predominantly fetal expressed T1 domain) (HUGO-approved symbol KCTD12 or C13orf2), by subtractive hybridization and differential screening of human fetal cochlear cDNA clones. Also, we have identified the mouse homolog, designated Pfet1. PFET1/Pfet1 encode a single transcript of approximately 6 kb in human, and three transcripts of approximately 4, 4.5, and 6 kb in mouse with a 70% GC-rich open reading frame (ORF) consisting of 978 bp in human and 984 bp in mouse. Both genes have unusually long 3' untranslated (3' UTR) regions (4996 bp in human PFET1, 3700 bp in mouse Pfet1) containing 12 and 5 putative polyadenylation consensus sequences, respectively. Pfetin, the protein encoded by PFET1/Pfet1, is predicted to have 325 amino acids in human and 327 amino acids in mouse and to contain a voltage-gated potassium (K+) channel tetramerization (T1) domain. Otherwise, to date these genes have no significant homology to any known gene. PFET1 maps to the long arm of human chromosome 13, in band q21 as shown by FISH analysis and STS mapping. Pfet1 maps to mouse chromosome 14 near the markers D14Mit8, D14Mit93, and D14Mit145.1. The human 6 kb transcript is present in a variety of fetal organs, with highest expression levels in the cochlea and brain and, in stark contrast, is detected only at extremely low levels in adult organs, such as brain and lung. Immunohistochemistry with a polyclonal antibody raised against a synthetic peptide to PFET1 sequence (pfetin) reveals immunostaining in a variety of cell types in human, monkey, mouse, and guinea pig cochleas and the vestibular system, including type I vestibular hair cells.
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Affiliation(s)
- Barbara L. Resendes
- />Department of Obstetrics, Gynecology and Reproductive
Biology, Brigham and Women’s Hospital, Boston, MA 02115 USA
- />Harvard Medical School, Boston, MA 02115 USA
| | - Sharon F. Kuo
- />Department of Obstetrics, Gynecology and Reproductive
Biology, Brigham and Women’s Hospital, Boston, MA 02115 USA
- />Speech and Hearing Bioscience and Technology Program, Harvard–MIT Division of Health Sciences and Technology, Cambridge, MA 02139 USA
| | - Nahid G. Robertson
- />Department of Obstetrics, Gynecology and Reproductive
Biology, Brigham and Women’s Hospital, Boston, MA 02115 USA
| | - Anne B. S. Giersch
- />Department of Pathology, Brigham and Women’s Hospital, Boston, MA 02115 USA
- />Harvard Medical School, Boston, MA 02115 USA
| | - Dynio Honrubia
- />Harvard Medical School, Boston, MA 02115 USA
- />Department of Neonatal Care, Children’s Hospital, Boston, MA 02115 USA
| | - Osamu Ohara
- />Kazusa DNA Research Institute, Chiba 292-0812, Japan
- />Laboratory of Immunogenomics, RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
| | - Joe C. Adams
- />Harvard Medical School, Boston, MA 02115 USA
- />Massachusetts Eye and Ear Infirmary, Boston, MA 02114 USA
| | - Cynthia C. Morton
- />Department of Obstetrics, Gynecology and Reproductive
Biology, Brigham and Women’s Hospital, Boston, MA 02115 USA
- />Department of Pathology, Brigham and Women’s Hospital, Boston, MA 02115 USA
- />Harvard Medical School, Boston, MA 02115 USA
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Hirose K, Liberman MC. Lateral wall histopathology and endocochlear potential in the noise-damaged mouse cochlea. J Assoc Res Otolaryngol 2004; 4:339-52. [PMID: 14690052 PMCID: PMC1805786 DOI: 10.1007/s10162-002-3036-4] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Noise exposure damages the stria and spiral ligament and may contribute to noise-induced threshold shift by altering the endocochlear potential (EP). The aim of this study was to correlate lateral wall histopathology with changes in EP and ABR thresholds. CBA/CaJ mice were exposed to octave band (8-16 kHz) noise for 2 h at intensities ranging from 94 to 116 dB SPL and evaluated 0 h to 8 weeks postexposure. EP in control mice averaged 86 and 101 mV in apical and basal turns, respectively. The 94 dB exposures caused a 40 dB temporary threshold shift (TTS), and there was with no corresponding change in EP. The 112 and 116 dB exposures caused >60 dB threshold shifts at 24 h, and EP was transiently decreased, e.g., to 21 and 27 mV in apical and basal turns after 116 dB. By 1 week postexposure, EP returned to control values in all exposure groups, although those exposed to 112 or 116 dB showed large permanent threshold shifts (PTS). Cochleas were plastic-embedded and serial-sectioned for light microscopic and ultrastructural analysis. Acute changes included degeneration of type II fibrocytes of the spiral ligament and strial edema. The strial swelling peaked at 24 h when significant EP recovery, had taken place, suggesting that these changes reflect compensatory volume changes. In the chronic state, massive loss of type II fibrocytes and degeneration of strial intermediate and marginal cells was observed with drastic reduction in membrane surface area. The results suggest that EP shifts do not occur with TTS and also do not add significantly to PTS in the steady state. However, EP loss could contribute to acute threshold shifts that resolve to a PTS. EP recovery despite significant strial degeneration may be partly due to decreased transduction current caused by hair cell damage.
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Affiliation(s)
- Keiko Hirose
- Department of Otolaryngology and Communicative Disorders, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
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Abstract
PURPOSE OF REVIEW Significant changes in population demographics with respect to age have taken place, and this pattern is expected to continue. The aging of the population underscores the importance of finding ways to improve the quality of life of the elderly. Most of the elderly population, however, suffers from progressive hearing loss: 60% of people older than 70 years have hearing loss of at least 25 dB. Age-related hearing loss affects the quality of life, not only of the elderly but also of their families and loved ones. RECENT FINDINGS The research goal in this field is to elucidate the mechanisms involved in age-related hearing loss and the molecular basis of normal and impaired auditory function, with the aim of developing preventative therapies. During the past few years, extraordinary progress has been made in the identification of genes that contribute to deafness. Additionally, inbred strains of mice have proven to be useful models to identify specific factors relevant to age-related hearing loss. A detailed description of the pathology exhibited by inbred mice that exhibit age-related hearing loss is helping to identify the specific structures and cell types affected by age-related hearing loss. A summary of current research efforts is presented. This review focuses on studies using inbred mice. SUMMARY By defining the molecular basis of normal and impaired auditory function, therapies can be developed to ameliorate the effects of aging in the auditory system.
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Affiliation(s)
- Michael Anne Gratton
- Department of Otolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, USA
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30
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Bok D, Galbraith G, Lopez I, Woodruff M, Nusinowitz S, BeltrandelRio H, Huang W, Zhao S, Geske R, Montgomery C, Van Sligtenhorst I, Friddle C, Platt K, Sparks MJ, Pushkin A, Abuladze N, Ishiyama A, Dukkipati R, Liu W, Kurtz I. Blindness and auditory impairment caused by loss of the sodium bicarbonate cotransporter NBC3. Nat Genet 2003; 34:313-9. [PMID: 12808454 DOI: 10.1038/ng1176] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2003] [Accepted: 04/30/2003] [Indexed: 11/08/2022]
Abstract
Normal sensory transduction requires the efficient disposal of acid (H+) generated by neuronal and sensory receptor activity. Multiple highly sensitive transport mechanisms have evolved in prokaryotic and eukaryotic organisms to maintain acidity within strict limits. It is currently assumed that the multiplicity of these processes provides a biological robustness. Here we report that the visual and auditory systems have a specific requirement for H+ disposal mediated by the sodium bicarbonate cotransporter NBC3 (refs. 7,8). Mice lacking NBC3 develop blindness and auditory impairment because of degeneration of sensory receptors in the eye and inner ear as in Usher syndrome. Our results indicate that in certain sensory organs, in which the requirement to transduce specific environmental signals with speed, sensitivity and reliability is paramount, the choice of the H+ disposal mechanism used is limited.
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Affiliation(s)
- Dean Bok
- Department of Neurobiology, Jules Stein Eye Institute, Los Angeles, California, 90095, USA
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31
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Lang H, Schulte BA, Schmiedt RA. Effects of chronic furosemide treatment and age on cell division in the adult gerbil inner ear. J Assoc Res Otolaryngol 2003; 4:164-75. [PMID: 12943371 PMCID: PMC3202712 DOI: 10.1007/s10162-002-2056-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Atrophy of the stria vascularis and spiral ligament and an associated decrease in the endocochlear potential (EP) are significant factors in age-related hearing loss (presbyacusis). To model this EP decrease, furosemide was delivered into the round-window niche of young adult gerbils by osmotic pump for seven days, chronically reducing the EP by 30-40 mV. Compound action potential (CAP) thresholds were correspondingly reduced by 30-40 dB SPL at high frequencies. Two weeks after withdrawal of furosemide, the treated ears showed an EP recovery of up to 20-30 mV along with a similar recovery of CAP thresholds. The influence of cell division on furosemide-induced and age-related decline of the EP was examined using a mitotic tracer, bromodeoxyuridine (BrdU). Cell proliferation was examined in three groups: young control, furosemide-treated, and aged cochleas. Sections immunostained for BrdU were bleached with H2O2 to eliminate ambiguities with melanin pigment in the inner ear. Cell types positively labeled for BrdU in all three groups included Schwann cells in Rosenthal's canal; glial cells in the osseous spiral lamina; fibrocytes in the limbus, sacculus, and spiral ligament (SL); epithelial cells in Reissner's and round-window membranes; intermediate cells in the stria vascularis; and vascular endothelial cells. Quantitative analysis showed that the mean number of BrdU-positive (BrdU+) intermediate cells in the stria did not differ significantly among the three groups. In contrast, there was a significant increase of BrdU + fibrocytes in the SL of furosemide-treated animals as compared to the young control group. Moreover, there was a significant decrease in labeled fibrocytes in the aged versus the young ears, particularly among the type II and type IV subtypes. The results suggest that the increased fibrocyte turnover in the SL after furosemide treatment may be related to the recovery of EP and CAP thresholds, supporting the hypothesis that fibrocyte proliferation may be essential for maintaining the EP and cochlear function in normal and damaged cochleas. Moreover, the decreased turnover of SL fibrocytes with age may be a contributing factor underlying the lateral wall pathology and consequent EP loss that often accompanies presbyacusis.
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Affiliation(s)
- H. Lang
- Department of Otolaryngology and Head–Neck Surgery, Medical University of South Carolina, Charleston, SC 29425, USA
| | - B. A. Schulte
- Department of Otolaryngology and Head–Neck Surgery, Medical University of South Carolina, Charleston, SC 29425, USA
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - R. A. Schmiedt
- Department of Otolaryngology and Head–Neck Surgery, Medical University of South Carolina, Charleston, SC 29425, USA
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Abstract
The ultrastructure of the spiral ligament was compared in aged and young gerbils to assess the involvement of connective tissues in the lateral wall and particularly the fibrocytes in development of presbyacusis. Pathologic features in fibrocytes of senescent gerbils spanned a wide range reflecting different stages of lateral wall involution. All of the type II, IV and V fibrocytes selectively developed cytosolic vacuoles in an early degenerative phase showing minimal strial involvement. Clear spaces indicative of interstitial edema separated the vacuolated cell bodies and their plasmalemmal processes. As a presumed intermediate phase, profiles of amorphous substance apparently derived from apoptosis/necrosis of type II fibrocytes infiltrated the type II fibrocyte area among nearly normal appearing cells. In cochlear turns with advanced strial degeneration, type II fibrocytes disappeared from the spiral prominence area leaving only type I-like fibrocytes occasionally accompanied by a collagen infiltrate. Type V fibrocytes disappeared similarly from the suprastrial area. The extent of atrophy in type II fibrocytes corresponded in general with that in the neighboring stria vascularis. Age-dependent atrophy in the lateral wall largely spared type I fibrocytes except that they often enclosed discrete amorphous foci lacking organelles. The involution thus affected principally the Na,K-ATPase-positive fibrocytes functioning in active uptake rather than passive conductance of K(+). The vacuolization and degeneration exclusive to ATPase-rich fibrocytes and the associated intercellular edema are interpreted as secondary responses, possibly as a result of impaired diffusion of K(+) through downstream marginal cells.
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Affiliation(s)
- Samuel S Spicer
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, 165 Ashley Avenue, Charleston, SC 29425, USA.
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Lang H, Schulte BA, Schmiedt RA. Endocochlear potentials and compound action potential recovery: functions in the C57BL/6J mouse. Hear Res 2002; 172:118-26. [PMID: 12361874 DOI: 10.1016/s0378-5955(02)00552-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The C57BL/6J mouse suffers from cochlear degeneration beginning at an early age and has been used as a model of age-related hearing loss (presbyacusis). Here, the endocochlear potential (EP) and compound action potential (CAP) responses were determined in one-, four-, 12- and 24-month-old C57BL/6J mice. CAP measures included thresholds to tone pips, input/output (I/O) functions, and recovery functions to conditioning tones. EP values among the four age groups did not differ significantly (P>0.05) in either the basal or apical turns. CAP thresholds were increased significantly by 10 to 30 dB in the four-month group compared to the one-month controls at 11.3, 16, 20, and 22.6 kHz. CAP I/O functions were shallower in the four-month group compared to controls at all frequencies. In the 12- and 24-month-old mice, CAP responses were absent, despite normal EP values in these animals. Recovery functions after conditioning tones were obtained at 8, 16, 20 and 22.6 kHz; the functions had fast and slow components at all frequencies tested in both the one- and four-month-old groups. The corresponding recovery curves were identical for both age groups, even with significant threshold shifts in the older group. The two component recovery curves provide the first physiological evidence that different spontaneous rate (SR) classes of auditory neurons exist in the C57BL/6J mouse. Moreover, the unchanged recovery functions in the older group suggest that there was no loss of activity of the low-SR fiber population with age under conditions where the EP remains stable, in contrast to the gerbil model of presbyacusis where there is a loss of low-SR fiber activity and EP does decline with age.
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Affiliation(s)
- H Lang
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, P.O. Box 250150, Walton Research Bldg, 39 Sabin St., Rm 608, Charleston, SC 29425, USA
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Hamann I, Gleich O, Klump GM, Kittel MC, Boettcher FA, Schmiedt RA, Strutz J. Behavioral and evoked-potential thresholds in young and old Mongolian gerbils (Meriones unguiculatus). Hear Res 2002; 171:82-95. [PMID: 12204352 DOI: 10.1016/s0378-5955(02)00454-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Age-dependent hearing loss has been well documented in gerbils exceeding 2 years of age using physiological methods (e.g. [Mills et al. (1990) Hear. Res. 46, 201-210]). We determined behavioral thresholds for broad-band noise and pure-tone pulses in gerbils as a function of age. Contrary to expectations based on previously published physiological data, we found no significant (broad-band noise and 10 kHz) or only a very small hearing loss (7 dB at 2 kHz) in 30-36-month-old animals. In animals over 3 years of age we observed an increased spread of thresholds and threshold shifts exceeding 20 dB in some individuals. Behavioral thresholds of old gerbils from two breeding colonies (University of Regensburg and Medical University of South Carolina) were similar. Data from individual animals where thresholds were determined physiologically and behaviorally indicate that results from auditory brainstem response measurements show no shift at 18 months while subsequent measurements at 28-29 months revealed age-dependent threshold shifts of 10-15 dB. In contrast, thresholds determined by behavioral methods in these same individuals at 31-33 months of age remained stable.
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Affiliation(s)
- Ingo Hamann
- HNO-Klinik, ENT-Department, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany
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Abstract
Mesenchymal nonsensory regions of the inner ear are important structures surrounding the neurosensory epithelium that are believed to participate in the ionic homeostasis of the cochlea and vestibule. We report here the discovery of otospiralin, an inner ear-specific protein that is produced by fibrocytes from these regions, including the spiral ligament and spiral limbus in the cochlea and the maculae and semicircular canals in the vestibule. Otospiralin is a novel 6.4 kDa protein of unknown function that shares a protein motif with the gag p30 core shell nucleocapsid protein of type C retroviruses. To evaluate its functional importance, we downregulated otospiralin by cochlear perfusion of antisense oligonucleotides in guinea pigs. This led to a rapid threshold elevation of the compound action potentials and irreversible deafness. Cochlear examination by transmission electron microscopy revealed hair cell loss and degeneration of the organ of Corti. This demonstrates that otospiralin is essential for the survival of the neurosensory epithelium.
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36
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Abstract
Cochleas from C57BL/6 mice were investigated electrophysiologically and histochemically to evaluate the pathology of presbycusis. The average auditory brainstem response thresholds from 6-week-old mice were significantly lower than those of 6-month-old mice and those of 1-year-old mice. Histologic observation revealed changes in the cochlea after age 6 months. Conventional hematoxylin and eosin (H&E) staining showed disorganization of the organ of Corti, a decrease in the number of spiral ganglion cells, and atrophy of the stria vascularis. Although H&E staining and type II collagen immunolabeling did not show obvious changes in the spiral ligament (SL), the density of connexin 26 staining was reduced in this region. Sodium-potassium-adenosinetriphosphatase immunolabeling was increased in the SL, whereas its average density was not significantly altered in the stria vascularis. These results suggest that the SL could be among the regions responsible for cochlear malfunction with aging.
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Affiliation(s)
- I Ichimiya
- Department of Otolaryngology, Oita Medical University, 1-1 Idaigaoka, Hasama-cho, Oita, Japan.
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37
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Sakaguchi N, Crouch JJ, Lytle C, Schulte BA. Na-K-Cl cotransporter expression in the developing and senescent gerbil cochlea. Hear Res 1998; 118:114-22. [PMID: 9606066 DOI: 10.1016/s0378-5955(98)00022-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Changes in the cellular expression pattern of the Na-K-Cl cotransporter (NKCC) were investigated during postnatal development and with advancing age in the gerbil cochlea. At birth, faint immunostaining for NKCC was discernable in the developing stria vascularis (StV), Reissner's membrane, interdental cells and some relatively undifferentiated cells lining the cochlear partition. Between 2 and 4 days after birth (DAB) immunostaining persisted and increased in the future interdental, inner and outer sulcus and claudius cells but then disappeared from these sites by 8 DAB. In contrast, NKCC immunoreactivity in the StV increased progressively during development and approached adult levels by 12 DAB. Immunostaining for NKCC in subpopulations of fibrocytes in the inferior portion of the spiral ligament, the suprastrial region and the spiral limbus was first detectable between 10 and 12 DAB and staining intensity reached adult levels around 16 DAB. Changes in NKCC expression with advancing age generally mimicked those previously observed for Na,K-ATPase in focal regions of atrophic lateral wall. Diminished immunostaining was first seen in the StV, presumably associated with the involution of the marginal cell's basolateral processes. Further atrophy culminated in complete loss of immunostaining in the StV and an associated down-regulation of NKCC expression in spiral ligament transport fibrocytes. The marked similarities in the developmental and age-related expression patterns of NKCC and Na,K-ATPase point to a high level of functional cooperativity between these two ion transport mediators, which together provide an efficient mechanism for generating and maintaining high K+ levels in endolymph and the endocochlear potential.
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Affiliation(s)
- N Sakaguchi
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston 29425, USA
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38
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Gratton MA, Smyth BJ, Lam CF, Boettcher FA, Schmiedt RA. Decline in the endocochlear potential corresponds to decreased Na,K-ATPase activity in the lateral wall of quiet-aged gerbils. Hear Res 1997; 108:9-16. [PMID: 9213117 DOI: 10.1016/s0378-5955(97)00034-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The ion transport-mediating enzyme, Na,K-ATPase, is abundantly present in the cochlear lateral wall. This enzyme is essential for the generation and maintenance of the endocochlear potential. Diminished enzyme activity has been observed previously in the lateral wall of quiet-aged gerbils. The present study was designed to investigate the impact of the age-related decline in Na,K-ATPase specific activity upon auditory function. Measures of the resting endocochlear potential value and the level of Na,K-ATPase specific activity were made in cochleae obtained from gerbils aged in quiet conditions. Analysis revealed a high degree of correspondence between the level of lateral wall Na,K-ATPase specific activity and the value of the endocochlear potential measured in the round window/turn 1 region of the cochlea. Nonlinear regression models showed a strong relationship between the age-related reductions in enzyme activity and the magnitude of the endocochlear potential. The data suggest that during metabolic presbyacusis a decrease in Na,K-ATPase specific activity can explain most, but not all, of the decline in the endocochlear potential.
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Affiliation(s)
- M A Gratton
- Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston 29425-2242, USA.
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