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Pan CC, Du ZH, Zhao Y, Chu HQ, Sun JW. Downregulation of Cav3.1 T-type Calcium Channel Expression in Age-related Hearing Loss Model. Curr Med Sci 2021; 41:680-686. [PMID: 34403092 DOI: 10.1007/s11596-021-2416-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/14/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Age-related hearing loss (AHL), characterized by degeneration of cochlea structures, is the most common sensory disorder among the elderly worldwide. The calcium channel is considered to contribute to normal hearing. However, the role of the T-type voltage-activated calcium channel, Cav3.1, remains unclear in AHL. Here, we investigate the age-related change of Cav3.1 expression in the cochlea and D-gal-induced senescent HEI-OC1 cells. METHODS Cochleae from C57BL/6 mice at 2 months and 12 months of age were assessed. Senescence in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells was induced by D-gal treatment. The immunofluorescence technique was employed to investigate the distribution of Cav3.1 in vivo and in vitro. Quantitative assessment was achieved by Western blotting and real-time PCR. RESULTS In comparison with 2-month-old animals, 12-month old C57BL/6 mice exhibited great loss of hair cells and elevated auditory brainstem threshold. The Cav3.1 was located in hair cells, spiral ganglion cells, lateral walls, and the expression of Cav3.1 protein and mRNA decreased in the aged cochleae. D-gal-induced senescence assay confirmed the down-regulation of Cav3.1 expression in senescent HEI-OC1 cells. CONCLUSION Our results show that age-related down-regulated expression of Cav3.1 in the cochleae is associated with AHL and may contribute to the pathogenesis of AHL.
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Affiliation(s)
- Chun-Chen Pan
- Department of Otorhinolaryngology-Head and Neck Surgery, the First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhi-Hui Du
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yi Zhao
- Department of Otorhinolaryngology-Head and Neck Surgery, the First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China
| | - Han-Qi Chu
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Jin-Wu Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, the First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China.
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Rai V, Wood MB, Feng H, Schabla NM, Tu S, Zuo J. The immune response after noise damage in the cochlea is characterized by a heterogeneous mix of adaptive and innate immune cells. Sci Rep 2020; 10:15167. [PMID: 32938973 PMCID: PMC7495466 DOI: 10.1038/s41598-020-72181-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023] Open
Abstract
Cells of the immune system are present in the adult cochlea and respond to damage caused by noise exposure. However, the types of immune cells involved and their locations within the cochlea are unclear. We used flow cytometry and immunostaining to reveal the heterogeneity of the immune cells in the cochlea and validated the presence of immune cell gene expression by analyzing existing single-cell RNA-sequencing (scRNAseq) data. We demonstrate that cell types of both the innate and adaptive immune system are present in the cochlea. In response to noise damage, immune cells increase in number. B, T, NK, and myeloid cells (macrophages and neutrophils) are the predominant immune cells present. Interestingly, immune cells appear to respond to noise damage by infiltrating the organ of Corti. Our studies highlight the need to further understand the role of these immune cells within the cochlea after noise exposure.
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MESH Headings
- Adaptive Immunity
- Animals
- B-Lymphocytes/immunology
- B-Lymphocytes/pathology
- Cochlea/immunology
- Cochlea/injuries
- Cochlea/pathology
- Disease Models, Animal
- Evoked Potentials, Auditory, Brain Stem/immunology
- Female
- Hearing Loss, Noise-Induced/immunology
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Immunity, Innate
- Killer Cells, Natural/immunology
- Killer Cells, Natural/pathology
- Leukocyte Common Antigens/metabolism
- Macrophages/immunology
- Macrophages/pathology
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Transgenic
- Neutrophils/immunology
- Neutrophils/pathology
- Organ of Corti/immunology
- Organ of Corti/injuries
- Organ of Corti/pathology
- RNA-Seq
- T-Lymphocytes/immunology
- T-Lymphocytes/pathology
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Affiliation(s)
- Vikrant Rai
- Department of Biomedical Science, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE, 68178, USA
| | - Megan B Wood
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, 733 N Broadway, Baltimore, MD, 21205, USA
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Hao Feng
- Department of Biomedical Science, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE, 68178, USA
| | - Nathan M Schabla
- Department of Medical Microbiology and Immunology and Flow Cytometry Core, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE, 68178, USA
| | - Shu Tu
- Department of Biomedical Science, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE, 68178, USA
| | - Jian Zuo
- Department of Biomedical Science, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE, 68178, USA.
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
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Kucharava K, Brand Y, Albano G, Sekulic-Jablanovic M, Glutz A, Xian X, Herz J, Bodmer D, Fuster DG, Petkovic V. Sodium-hydrogen exchanger 6 (NHE6) deficiency leads to hearing loss, via reduced endosomal signalling through the BDNF/Trk pathway. Sci Rep 2020; 10:3609. [PMID: 32107410 PMCID: PMC7046661 DOI: 10.1038/s41598-020-60262-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/07/2020] [Indexed: 01/03/2023] Open
Abstract
Acid-base homeostasis is critical for normal growth, development, and hearing function. The sodium-hydrogen exchanger 6 (NHE6), a protein mainly expressed in early and recycling endosomes, plays an important role in regulating organellar pH. Mutations in NHE6 cause complex, slowly progressive neurodegeneration. Little is known about NHE6 function in the mouse cochlea. Here, we found that all NHE isoforms were expressed in wild-type (WT) mouse cochlea. Nhe6 knockout (KO) mice showed significant hearing loss compared to WT littermates. Immunohistochemistry in WT mouse cochlea showed that Nhe6 was localized in the organ of Corti (OC), spiral ganglion (SG), stria vascularis (SV), and afferent nerve fibres. The middle and the inner ears of WT and Nhe6 KO mice were not different morphologically. Given the putative role of NHE6 in early endosomal function, we examined Rab GTPase expression in early and late endosomes. We found no change in Rab5, significantly lower Rab7, and higher Rab11 levels in the Nhe6 KO OC, compared to WT littermates. Because Rabs mediate TrkB endosomal signalling, we evaluated TrkB phosphorylation in the OCs of both strains. Nhe6 KO mice showed significant reductions in TrkB and Akt phosphorylation in the OC. In addition, we examined genes used as markers of SG type I (Slc17a7, Calb1, Pou4f1, Cal2) and type II neurons (Prph, Plk5, Cacna1g). We found that all marker gene expression levels were significantly elevated in the SG of Nhe6 KO mice, compared to WT littermates. Anti-neurofilament factor staining showed axon loss in the cochlear nerves of Nhe6 KO mice compared to WT mice. These findings indicated that BDNF/TrkB signalling was disrupted in the OC of Nhe6 KO mice, probably due to TrkB reduction, caused by over acidification in the absence of NHE6. Thus, our findings demonstrated that NHEs play important roles in normal hearing in the mammalian cochlea.
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Affiliation(s)
- Krystsina Kucharava
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Yves Brand
- Clinic for Otolaryngology, Head and Neck Surgery, Kantonsspital Graubünden, Chur, 7000, Switzerland
| | - Giuseppe Albano
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, and NCCR Transcure, University of Bern, Bern, Switzerland
| | - Marijana Sekulic-Jablanovic
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Andrea Glutz
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Xunde Xian
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Joachim Herz
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Daniel Bodmer
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Daniel G Fuster
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, and NCCR Transcure, University of Bern, Bern, Switzerland
| | - Vesna Petkovic
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland.
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Choi MJ, Kang H, Lee YY, Choo OS, Jang JH, Park SH, Moon JS, Choi SJ, Choung YH. Cisplatin-Induced Ototoxicity in Rats Is Driven by RIP3-Dependent Necroptosis. Cells 2019; 8:E409. [PMID: 31052605 PMCID: PMC6562419 DOI: 10.3390/cells8050409] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/25/2019] [Accepted: 04/30/2019] [Indexed: 12/22/2022] Open
Abstract
Cisplatin-induced early-onset ototoxicity is linked to hearing loss. The mechanism by which cisplatin causes ototoxicity remains unclear. The purpose of this study was to identify the involvement of receptor-interacting protein kinase (RIP)3-dependent necroptosis in cisplatin-induced ototoxicity in vitro and in vivo. Sprague-Dawley rats (SD, 8 week) were treated via intraperitoneal (i.p.) injection with cisplatin (16 mg/kg for 1 day), and their hearing thresholds were measured by the auditory brainstem response (ABR) method. Hematoxylin and eosin (H & E) staining, immunohistochemistry, and western blots were performed to determine the effect of cisplatin-induced ototoxicity on cochlear morphology. Inhibitor experiments with necrostatin 1 (Nec-1) and Z-VAD were also performed in HEI-OC1 cell line. H&E stains revealed that the necroptotic changes were increased in the organ of Corti (OC) and spiral ganglion neurons (SGNs). Moreover, immunohistochemistry and western blot analysis showed that cisplatin treatment increased the protein levels of RIP3 in both OCs and SGNs. The treatment of Nec-1, a selective RIP1 inhibitor, resulted in markedly suppression of cisplatin-induced cell death in HEI-OC1 cells, whereas Z-VAD treatment did not change the cisplatin-induced cell death. Our results suggest that RIP3-dependent necroptosis was substantial in cisplatin-induced ototoxicity; inner cochlear regions, the OCs, and SGNs were especially sensitive to necroptosis.
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Affiliation(s)
- Mi-Jin Choi
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Hyunsook Kang
- Department of Otolaryngology-Head and Neck Surgery, Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan 31151, Korea.
| | - Yun Yeong Lee
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Oak-Sung Choo
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Jeong Hun Jang
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Sung-Hee Park
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
| | - Jong-Seok Moon
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan 31151, Korea.
| | - Seong Jun Choi
- Department of Otolaryngology-Head and Neck Surgery, Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan 31151, Korea.
| | - Yun-Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea.
- Bk21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea.
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5
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Watabe T, Xu M, Watanabe M, Nabekura J, Higuchi T, Hori K, Sato MP, Nin F, Hibino H, Ogawa K, Masuda M, Tanaka KF. Time-controllable Nkcc1 knockdown replicates reversible hearing loss in postnatal mice. Sci Rep 2017; 7:13605. [PMID: 29051615 PMCID: PMC5648887 DOI: 10.1038/s41598-017-13997-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/04/2017] [Indexed: 11/08/2022] Open
Abstract
Identification of the causal effects of specific proteins on recurrent and partially reversible hearing loss has been difficult because of the lack of an animal model that provides reversible gene knockdown. We have developed the transgenic mouse line Actin-tTS::Nkcc1 tetO/tetO for manipulatable expression of the cochlear K+ circulation protein, NKCC1. Nkcc1 transcription was blocked by the binding of a tetracycline-dependent transcriptional silencer to the tetracycline operator sequences inserted upstream of the Nkcc1 translation initiation site. Administration of the tetracycline derivative doxycycline reversibly regulated Nkcc1 knockdown. Progeny from pregnant/lactating mothers fed doxycycline-free chow from embryonic day 0 showed strong suppression of Nkcc1 expression (~90% downregulation) and Nkcc1 null phenotypes at postnatal day 35 (P35). P35 transgenic mice from mothers fed doxycycline-free chow starting at P0 (delivery) showed weaker suppression of Nkcc1 expression (~70% downregulation) and less hearing loss with mild cochlear structural changes. Treatment of these mice at P35 with doxycycline for 2 weeks reactivated Nkcc1 transcription to control levels and improved hearing level at high frequency; i.e., these doxycycline-treated mice exhibited partially reversible hearing loss. Thus, development of the Actin-tTS::Nkcc1 tetO/tetO transgenic mouse line provides a mouse model for the study of variable hearing loss through reversible knockdown of Nkcc1.
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Affiliation(s)
- Takahisa Watabe
- Department of Otolaryngology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Ming Xu
- Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka, 431-3192, Japan
| | - Junichi Nabekura
- Division of Homeostatic Development, National Institute for Physiological Sciences, 38 Nishigonaka Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Taiga Higuchi
- Department of Molecular Physiology, Niigata University School of Medicine, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata, 951-8510, Japan
| | - Karin Hori
- Department of Molecular Physiology, Niigata University School of Medicine, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata, 951-8510, Japan
| | - Mitsuo P Sato
- Department of Molecular Physiology, Niigata University School of Medicine, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata, 951-8510, Japan
| | - Fumiaki Nin
- Department of Molecular Physiology, Niigata University School of Medicine, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata, 951-8510, Japan
| | - Hiroshi Hibino
- Department of Molecular Physiology, Niigata University School of Medicine, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata, 951-8510, Japan
- Center for Transdisciplinary Research, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Masatsugu Masuda
- Department of Otolaryngology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
- Department of Otolaryngology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka-shi, Tokyo, 181-8611, Japan.
| | - Kenji F Tanaka
- Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
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Albee RR, Spencer PJ, Johnson KA, Bradley GJ, Marable BR, Wilmer JW, Mattsson JL. Lack of Trigeminal Nerve Toxicity in Rats Exposed to Trichloroethylene Vapor for 13 Weeks. Int J Toxicol 2016; 25:531-40. [PMID: 17132611 DOI: 10.1080/10915810600972678] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Male and female Fischer-344 rats were exposed to 1,1,2-trichloroethylene (TCE) at 250, 800, or 2500 ppm for 6 h/day, 5 days/week, for 13 weeks. Weekly body weights and daily clinical observations were recorded and a functional observational battery (FOB) was performed monthly. Postexposure neurotoxicological evaluations included an electrodiagnostic evaluation of auditory function, the trigeminal nerve, and a comprehensive neuropathological examination. After 8 weeks of exposure, female, but not male, rats exposed to 2500 ppm were slightly more reactive to handling than the controls but not after 13 weeks of exposure. After 13 weeks, female rats exposed to 2500 ppm TCE were slightly more active during the 1-min observation period than the controls. There were no treatment-related differences in grip performance, landing foot splay, or on the trigeminal nerve–evoked potential at any dose. At 2500 ppm TCE, mild frequency-specific hearing deficits were observed, including elevated tone-pip auditory brainstem response thresholds. Focal loss of hair cells in the upper basal turn of the cochlea was observed in 2500 ppm–exposed rats. Except for the cochleas of 2500 ppm–exposed rats, no treatment-related lesions were noted during the neuro-histopathologic examination. The no-observable-adverse-effect level for this study was 800 ppm based on ototoxicity at 2500 ppm.
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Affiliation(s)
- Ralph R Albee
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA.
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Abstract
Sense organ deposits have been described in temporal bones from patients with vestibular neuronitis, Meniere's disease, and benign paroxysmal positional vertigo that are not found in a comparable series of temporal bones without vestibulopathy. Because the recurrent vestibulopathies are caused by vestibular ganglionitis and the vestibulocochlear anastomosis was degenerated in these temporal bones, the deposits may represent the end buds of regenerating efferent axons injured in passage through the vestibular ganglion. Such neural buds have been described with transmission electron microscopy in animals after vestibular nerve transection and in a human temporal bone with endolymphatic hydrops. The buds may be visible by light microscopy, because their size is comparable to that of hair cell nuclei and they stain blue with hematoxylin because of their nucleic acid content. The variable location and size of these deposits (buds) in the labyrinthine sense organs is described to aid in the recognition of efferent system injury in human temporal bones.
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Affiliation(s)
- Richard R Gacek
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of South Alabama College of Medicine, Mobile, Alabama 36688-0002, USA
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Abstract
BACKGROUND: Amikacin is a semisynthetic aminoglycoside. It acts against most of the microbial species. Amikacin limitation of the therapeutic application is the ototoxicity which promotes permanent lesions in the cochlear system. Aminoglycoside antibiotics have ototoxic potential. The target cells are preferentially the outer hair cells in the cochlear basal turns. Amynoglicoside antibiotics can quelate iron forming a complex with oxidate properties and promotes the formation of free radicals. Responsible for production of lesions in the hair cells. OBJECTIVE: The objective of the present investigation was to determine whether the use of the aminoglycoside amikacin at small doses may lead to the occurrence of some types of resistance to or protection against ototoxicity of the drug by analyzing lesions to the organ of Corti by scanning electron microscopy. METHODS: The study was conducted on 31 guinea pigs that were divided into 4 groups, amikacin was administered intramuscularly. The groups consisted of: group A = control group: 5 animals (10 cochleae); group B = 5 animals (10 cochleae), amikacin 20 mg/kg/day for 30 days; group c = 7 animals (13 cochleae), amikacin 400 mg/kg/day for 12 days; group d = 14 animals (26 cochleae) amikacin 20 mg/kg/day for 30 days, followed by 400 mg/kg/day for 12 days. Histological studies were performed by scanning electron microscopy. Three cochleae were excluded. RESULTS: In groups A and B, the cells were normal in all cochleae, in group C there were extensive lesions of the 2 more basal turns, and in group D there was a significant reduction of lesions in the 2 more basal turns compared with group C, which had received the ototoxic dose of amikacin alone. CONCLUSION: We conclude that the non-ototoxic dose of amikacin administered before the ototoxic dose of the same antibiotic had a statistically significant protective effect on the 2 more basal turns of the guinea pig cochlea.
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Affiliation(s)
- J A A de Oliveira
- Servicio de Otorhinolaryngology, University Hospital, Faculty of Medicine of Ribeirão Preto, São Paulo, Brazil
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Niwa K, Matsunobu T, Kurioka T, Kamide D, Tamura A, Tadokoro S, Satoh Y, Shiotani A. The beneficial effect of Hangesha-shin-to (TJ-014) in gentamicin-induced hair cell loss in the rat cochlea. Auris Nasus Larynx 2016; 43:507-13. [PMID: 26797463 DOI: 10.1016/j.anl.2015.12.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/26/2015] [Accepted: 12/23/2015] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Ototoxic damage caused by aminoglycosides (AG) leads to the loss of cochlear hair cells (HCs). In mammals, mature cochlear HCs are unable to regenerate, and their loss results in permanent hearing deficits. Our objective was to protect the inner ear from damage after an AG challenge. The generation of reactive oxygen species (ROS), one of the earliest events in the process of AG ototoxicity, is considered to play a key role in the initiation of HC death. We examined whether Hangesha-shin-to (TJ-014), a traditional Japanese Kampo medicine considered to be a potent antioxidant, protects HCs from gentamicin (GM)-induced damage. METHODS Organ of Corti explants removed from postnatal day 3-5 rats were maintained in tissue culture and exposed to 50μM GM for up to 48h. The effects of TJ-014 on GM-induced ototoxicity were assessed by HC counts and immunohistochemistry against cleaved caspase-3, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and a probe reacting to mitochondrial function changes. RESULTS TJ-014 treatments significantly reduced GM-induced HC loss and immunoreactivities for cleaved caspase-3 and 8-OHdG; these effects were correlated with increasing TJ-014 concentrations. Moreover, TJ-014 protected the mitochondrial membrane potential from GM ototoxicity. CONCLUSION These findings indicate the potential of TJ-014 to prevent GM-induced cochlear damage involving ROS.
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Affiliation(s)
- Katsuki Niwa
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
| | - Takeshi Matsunobu
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan; Division of Otolaryngology, New Tokyo Hospital, 1271 Wanagaya, Matsudo, Japan.
| | - Takaomi Kurioka
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
| | - Daisuke Kamide
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
| | - Atsushi Tamura
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
| | - Shin Tadokoro
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
| | - Yasushi Satoh
- Department of Anesthesiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Japan
| | - Akihiro Shiotani
- Department of Otolaryngology, Head and Neck Surgery, National Defense Medical College, Japan
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10
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Abstract
OBJECTIVE This study was designed to determine if hearing status monitoring during intravenous infusion of EA reduces individual variability and to evaluate the correlation between EA dose and Bwt. MATERIALS AND METHODS Twenty-five cats with the mean age of 24 ± 3.7 weeks (range = 20.6-28.3) and a mean weight of 3.21 ± 0.84 kg (range = 1.9-5.1) were administered a subcutaneous injection of KM (300 mg/kg) followed by an intravenous infusion of EA (1 mg/min). Click-evoked auditory brainstem responses (ABRs) were recorded to monitor hearing during the infusion. When ABR thresholds exceeded a 90 dB sound pressure level, the infusion of EA was terminated. Histopathology forapex, middle, and base sections of the cochlea were examined after 6 months. RESULTS The dose of EA was optimized for deafening through simultaneous ABR measurements. Bwt was positively correlated with EA dose (mg) (p < 0.001, R(2) = 0.548), which was different from a study previously reported. Cochlear histopathology assessments revealed an absence of organ of Corti in the majority of cochleae. CONCLUSION Co-administration of kanamycin (KM) and ethacrynic acid (EA) was an easy and effective method for deafening procedures in adult animals. Body weight (Bwt) was positively correlated with EA dose (mg) and an optimal EA dose can be calculated.
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Affiliation(s)
- Jeong Hun Jang
- a Department of Otorhinolaryngology , Kyungpook National University College of Medicine , Daegu , Korea
| | - Ho Sun Lee
- b Department of Otorhinolaryngology , Boramae Medical Center, Seoul Metropolitan Government-Seoul National University , Seoul , Korea
| | - Seung Ha Oh
- c Department of Otorhinolarynogology , Seoul National University College of Medicine , Seoul , Korea
- d Research Center for Sensory Organs, Medical Research Center, Seoul National University College of Medicine , Seoul , Korea
| | - Min-Hyun Park
- b Department of Otorhinolaryngology , Boramae Medical Center, Seoul Metropolitan Government-Seoul National University , Seoul , Korea
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Melnick M, Jaskoll T. CMV-induced embryonic mouse organ of corti dysplasia: Network architecture of dysfunctional lateral inhibition. ACTA ACUST UNITED AC 2015; 103:573-82. [PMID: 26178632 DOI: 10.1002/bdra.23386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 03/18/2015] [Accepted: 04/14/2015] [Indexed: 11/07/2022]
Abstract
BACKGROUND Congenital cytomegalovirus infection is the major nongenetic cause of sensorineural hearing loss at birth and beyond. Among other pathologies, there is a striking dysplasia/hyperplasia of organ of Corti hair and supporting cells. METHODS Using an in vitro embryonic mouse model of cytomegalovirus-induced cochlear teratogenesis that mimics the known human pathology, and functional signaling network modeling, we tested the hypothesis that cytomegalovirus disrupts the highly ordered organ of Corti hair and supporting cells pattern by dysregulating Notch and Fgfr3, their cognate ligands and downstream effectors. RESULTS Several novel emergent properties of the critical lateral inhibition subnetwork became apparent. The subnetwork has classic small-world properties such as short paths between most gene pairs, few long-distance links, and considerable clustering. Concomitantly, the calculated probability that our specific gene expression dataset is from dysplastic organs of Corti is highly significant (p < 1 × 10(-12) ). Furthermore, we determined that the subnetwork has a highly heterogeneous scale-free topology in which the highly linked genes (hubs), Notch and Fgfr3, play a central role in mediating interactions among the less linked genes. CONCLUSION This phenomenon has important biologic and therapeutic implications.
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Affiliation(s)
- Michael Melnick
- Laboratory Developmental Genetics, University of Southern California, Los Angeles, California
| | - Tina Jaskoll
- Laboratory Developmental Genetics, University of Southern California, Los Angeles, California
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Estève-Fraysse MJ, Corvera G, Deguine O, Sans A, Vincent M, Laur D, Sonilhac F. Significance of the promontory test: histological and electrical results. Adv Otorhinolaryngol 2015; 48:97-102. [PMID: 8273509 DOI: 10.1159/000422566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Eldredge DH, Mills JH, Bohne BA. Anatomical, behavioral, and electrophysiological observations on chinchillas after long exposures to noise. Adv Otorhinolaryngol 2015; 20:64-81. [PMID: 4575762 DOI: 10.1159/000393089] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Higashi T, Katsuno T, Kitajiri SI, Furuse M. Deficiency of angulin-2/ILDR1, a tricellular tight junction-associated membrane protein, causes deafness with cochlear hair cell degeneration in mice. PLoS One 2015; 10:e0120674. [PMID: 25822906 PMCID: PMC4378975 DOI: 10.1371/journal.pone.0120674] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/05/2015] [Indexed: 11/18/2022] Open
Abstract
Tricellular tight junctions seal the extracellular spaces of tricellular contacts, where the vertices of three epithelial cells meet, and are required for the establishment of a strong barrier function of the epithelial cellular sheet. Angulins and tricellulin are known as specific protein components of tricellular tight junctions, where angulins recruit tricellulin. Mutations in the genes encoding angulin-2/ILDR1 and tricellulin have been reported to cause human hereditary deafness DFNB42 and DFNB49, respectively. To investigate the pathogenesis of DFNB42, we analyzed mice with a targeted disruption of Ildr1, which encodes angulin-2/ILDR1. Ildr1 null mice exhibited profound deafness. Hair cells in the cochlea of Ildr1 null mice develop normally, but begin to degenerate by two weeks after birth. Tricellulin localization at tricellular contacts of the organ of Corti in the cochlea was retained in Ildr1 null mice, but its distribution along the depth of tricellular contacts was affected. Interestingly, compensatory tricellular contact localization of angulin-1/LSR was observed in the organ of Corti in Ildr1 null mice although it was hardly detected in the organ of Corti in wild-type mice. The onset of hair cell degeneration in Ildr1 null mice was earlier than that in the reported Tric mutant mice, which mimic one of the tricellulin mutations in DFNB49 deafness. These results indicate that the angulin-2/ILDR1 deficiency causes the postnatal degenerative loss of hair cells in the cochlea, leading to human deafness DFNB42. Our data also suggest that angulin family proteins have distinct functions in addition to their common roles of tricellulin recruitment and that the function of angulin-2/ILDR1 for hearing cannot be substituted by angulin-1/LSR.
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Affiliation(s)
- Tomohito Higashi
- Division of Cell Biology, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tatsuya Katsuno
- Department of Otolaryngology—Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shin-ichiro Kitajiri
- Department of Otolaryngology—Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- * E-mail: (SK); (MF)
| | - Mikio Furuse
- Division of Cell Biology, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan
- Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
- * E-mail: (SK); (MF)
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Abstract
Conclusion: As the periods of intratympanic injection of ovalbumin (OVA) to the middle ear became longer, marked eosinophil infiltration in the perilymphatic space was observed. Moreover severe morphological damage of the organ of Corti was observed in the 28-day antigen-stimulation side. These results indicate that eosinophilic inflammation occurred in the inner ear and caused profound hearing loss. Objective: The purpose of the present study was to elucidate the inner ear damage in a new animal model of eosinophilic otitis media (EOM) which we recently constructed. Methods: We constructed the animal model of EOM by intraperitoneal and intratympanic injection of OVA. Infiltrating cells and the inner ear damage were examined by histological study. Results: In the inner ear, a few eosinophils were seen in the scala tympani of the organ of Corti and the dilation of capillaries of the stria vascularis was observed in the 7-day stimulation side. In the 14-day antigen stimulation side, some eosinophils and macrophages were seen in not only the scala tympani but also the scala vestibule. In the 28-day antigen-stimulation side, severe morphological damage of the organ of Corti and many eosinophils, red blood cells, and plasma cells infiltrating the perilymph were observed.
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Affiliation(s)
- Atsushi Matsubara
- Department of Otorhinolaryngology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
| | - Hisanori Nishizawa
- Department of Otorhinolaryngology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
| | - Akira Kurose
- Department of Anatomic Pathology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
| | - Takashi Nakagawa
- Department of Otorhinolaryngology, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Junko Takahata
- Department of Otorhinolaryngology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
| | - Akira Sasaki
- Department of Otorhinolaryngology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
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Chen S, Sun Y, Lin X, Kong W. Down regulated connexin26 at different postnatal stage displayed different types of cellular degeneration and formation of organ of Corti. Biochem Biophys Res Commun 2014; 445:71-7. [PMID: 24491564 DOI: 10.1016/j.bbrc.2014.01.154] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 11/18/2022]
Abstract
Connexin26 (Cx26) mutation is the most common cause for non-syndromic hereditary deafness. Different congenital Cx26 null mouse models revealed a profound hearing loss pattern and developmental defect in the cochlea. Our study aimed at establishing a Cx26 knocking down mouse model at different postnatal time points and to investigate the time course and pattern of the hearing loss and cell degeneration in these models. Morphologic changes were observed for 5 months to detect long-term diversities among these models. Depending on the time point when Cx26 expression was reduced, mild to profound hearing loss patterns were found in different groups. Malformed organ of Corti with distinct cell loss in middle turn was observed only in early Cx26 reduction group while mice in late Cx26 reduction group developed normal organ of Corti and only suffered a few hair loss in the basal turn. These results indicated that Cx26 may play essential roles in the postnatal maturation of the cochlea, and its role in normal hearing at more mature stage may be replaceable.
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Affiliation(s)
- Sen Chen
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Yu Sun
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Weijia Kong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China; Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
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Stathopoulos D, Chambers S, Enke YL, Timbol G, Risi F, Miller C, Cowan R, Newbold C. Development of a safe dexamethasone-eluting electrode array for cochlear implantation. Cochlear Implants Int 2014; 15:254-63. [PMID: 24621150 DOI: 10.1179/1754762813y.0000000054] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES Cochlear implantation can result in trauma leading to increased tissue response and loss of residual hearing. A single intratympanic application of the corticosteroid dexamethasone is sometimes used clinically during surgery to combat the potential effect of trauma on residual hearing. This project looked at the safety and efficacy of dexamethasone eluted from an intracochlear array in vivo. METHODS Three trials were conducted using normal hearing adult guinea pigs implanted with successive iterations of dexamethasone-eluting (DX1, DX2, and DX3) or non-eluting (control) intracochlear electrode arrays. The experimental period for each animal was 90 days during which hearing tests were performed at multiple time points. RESULTS There was no significant difference between matched control array and dexamethasone array groups in terms of spiral ganglion neuron density, organ of Corti condition, or fibrosis and ossification. A cochleostomy seal was present in all implanted cochleae. There were no differences in the degree of hearing threshold shifts between DX1 and DX3 and their respective control arrays. Cochleae implanted with DX2 arrays showed less hearing loss and marginally better spiral ganglion neuron survival than their control array counterparts. Post-explant inspection of the DX2 and DX3 arrays revealed a difference in pore density following dexamethasone elution. CONCLUSION The dexamethasone doses used were safe in the guinea pig cochlea. Dexamethasone did not inhibit formation of a cochleostomy seal. The level of hearing protection afforded by dexamethasone eluting from an intracochlear array may depend upon the degree of elution and level of trauma inflicted.
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Abstract
There is a high prevalence of behavioral disorders that feature hyperactivity in individuals with severe inner ear dysfunction. What remains unknown is whether inner ear dysfunction can alter the brain to promote pathological behavior. Using molecular and behavioral assessments of mice that carry null or tissue-specific mutations of Slc12a2, we found that inner ear dysfunction causes motor hyperactivity by increasing in the nucleus accumbens the levels of phosphorylated adenosine 3',5'-monophosphate response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase (pERK), key mediators of neurotransmitter signaling and plasticity. Hyperactivity was remedied by local administration of the pERK inhibitor SL327. These findings reveal that a sensory impairment, such as inner ear dysfunction, can induce specific molecular changes in the brain that cause maladaptive behaviors, such as hyperactivity, that have been traditionally considered exclusively of cerebral origin.
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Affiliation(s)
- Michelle W. Antoine
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Christian A Hübner
- Jena University Hospital, Institute of Human Genetics, Jena 07743, Germany
| | - Joseph C. Arezzo
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jean M. Hébert
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Abstract
Sensorineural hearing loss is the most common type of hearing loss worldwide, yet the underlying cause is typically unknown because the inner ear cannot be biopsied today without destroying hearing, and intracochlear cells have not been imaged with resolution sufficient to establish diagnosis. Intracochlear imaging has been technologically challenging because of the cochlea's small size and encasement in bone. We report, for the first time, imaging of the mouse cochlea in situ without exogenous dyes, through a membranous round window, using a near-infrared femtosecond laser as the excitation and endogenous two-photon excitation fluorescence (TPEF) and second harmonic generation as the contrast mechanisms. We find that TPEF exhibits strong contrast allowing cellular, and even subcellular resolution, and detection of specific, noise-induced pathologic changes. Our results demonstrate that the round window provides a useful access to the cochlea through the middle ear, and they motivate future development of a new and efficient diagnostic tool based on two-photon micro-endoscopy.
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Affiliation(s)
- Xin Yang
- École Polytechnique Fédérale de Lausanne, School of Engineering, Optics Laboratory, BM 4.107, Station 17, CH-1015 Lausanne, Switzerland
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Han WJ, Shi XR, Nuttall A. Noise-induced nitrotyrosine increase and outer hair cell death in guinea pig cochlea. Chin Med J (Engl) 2013; 126:2923-2927. [PMID: 23924469 PMCID: PMC3947561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Modern research has provided new insights into the biological mechanisms of noise-induced hearing loss, and a number of studies showed the appearance of increased reactive oxygen species (ROS) and reactive nitrogen species (RNS) during and after noise exposure. This study was designed to investigate the noise exposure induced nitrotyrosine change and the mechanism of outer hair cells death in guinea pig cochlea. METHOD Thirty guinea pigs were used in this study. The experimental animals were either exposed for 4 hours per day to broadband noise at 122 dB SPL (A-weighted) for 2 consecutive days or perfused cochleae with 5 mg/ml of the SIN1 solutions, an exogenous NO and superoxide donor, for 30 minutes. Then the cochleae of the animals were dissected. Propidium iodide (PI), a DNA intercalating fluorescent probe, was used to trace morphological changes in OHC nuclei. The distribution of nitrotyrosine (NT) in the organ of Corti and the cochlear lateral wall tissue from the guinea pigs were examined using fluorescence immunohistochemistry method. Whole mounts of organ of Corti were prepared. Morphological and fluorescent changes were examined under a confocal microscope. RESULTS Either after noise exposure or after SIN1 perfusion, outer hair cells (OHCs) death with characteristics of both apoptotic and necrotic degradation appeared. Nitrotyrosine immunolabeling could be observed in the OHCs from the control animals. After noise exposure, NT immunostaining became much greater than the control animals in OHCs. The apoptotic OHC has significant increase of nitrotyrosine in and around the nucleus following noise exposure. In the normal later wall of cochleae, relatively weak nitrotyrosine immunolabeling could be observed. After noise exposure, nitrotyrosine immunoactivity became stronger in stria vascularis. CONCLUSION Noise exposure induced increase of nitrotyrosine production is associated with OHCs death suggesting reactive nitrogen species participation in the cochlear pathophysiology of noise-induced hearing loss.
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Affiliation(s)
- Wei-ju Han
- Department of Otolaryngology Head and Neck Surgery, Chinese People's Liberation Army General Hospital, Beijing 100853, China.
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San Román J, Carricondo F, Iglesias-Moreno MC, Martín-Villares C, Poch-Broto J, Gil-Loyzaga P. Electrophysiological monitoring of hearing function during cochlear perilymphatic perfusions. Acta Otolaryngol 2012; 132:916-22. [PMID: 22667457 DOI: 10.3109/00016489.2012.678945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION The cochlear perilymphatic perfusion produces, by itself, significant effects in the cochlear physiology that could be associated with the surgical procedure. These effects need to be well characterized to allow a reliable quantification of the effects of the experimental agent being tested. OBJECTIVES The study focused on the accurate description of the electrophysiological effects on the cochlear potential recordings of perilymphatic perfusions. METHODS Two successive cochlear perilymphatic perfusions were carried out. The first used artificial perilymph. The second used artificial perilymph alone or a kainic acid (KA) solution in artificial perilymph. The compound action potential of the auditory nerve (CAP-AN) was recorded: (1) before the first perfusion, (2) after the first perfusion and (3) after the second perfusion, and compared between groups. RESULTS The first intracochlear perfusion with artificial perilymph produced significant effects in the CAP-AN that could be related to the surgical procedure. These effects were analysed separately from the effects produced by the KA. In particular, the KA administered intracochlearly produced a significant increase in the latency and a decrease in the amplitude of the CAP-AN N1 wave compared with the controls that were perfused twice with artificial perilymph.
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Affiliation(s)
- Jesús San Román
- Otorhinolaryngology Service, Hospital Comarcal de El Bierzo Ponferrada, Spain
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Taylor RR, Jagger DJ, Forge A. Defining the cellular environment in the organ of Corti following extensive hair cell loss: a basis for future sensory cell replacement in the Cochlea. PLoS One 2012; 7:e30577. [PMID: 22299045 PMCID: PMC3267727 DOI: 10.1371/journal.pone.0030577] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 12/21/2011] [Indexed: 01/01/2023] Open
Abstract
Background Following the loss of hair cells from the mammalian cochlea, the sensory epithelium repairs to close the lesions but no new hair cells arise and hearing impairment ensues. For any cell replacement strategy to be successful, the cellular environment of the injured tissue has to be able to nurture new hair cells. This study defines characteristics of the auditory sensory epithelium after hair cell loss. Methodology/Principal Findings Studies were conducted in C57BL/6 and CBA/Ca mice. Treatment with an aminoglycoside-diuretic combination produced loss of all outer hair cells within 48 hours in both strains. The subsequent progressive tissue re-organisation was examined using immunohistochemistry and electron microscopy. There was no evidence of significant de-differentiation of the specialised columnar supporting cells. Kir4.1 was down regulated but KCC4, GLAST, microtubule bundles, connexin expression patterns and pathways of intercellular communication were retained. The columnar supporting cells became covered with non-specialised cells migrating from the outermost region of the organ of Corti. Eventually non-specialised, flat cells replaced the columnar epithelium. Flat epithelium developed in distributed patches interrupting regions of columnar epithelium formed of differentiated supporting cells. Formation of the flat epithelium was initiated within a few weeks post-treatment in C57BL/6 mice but not for several months in CBA/Ca's, suggesting genetic background influences the rate of re-organisation. Conclusions/Significance The lack of dedifferentiation amongst supporting cells and their replacement by cells from the outer side of the organ of Corti are factors that may need to be considered in any attempt to promote endogenous hair cell regeneration. The variability of the cellular environment along an individual cochlea arising from patch-like generation of flat epithelium, and the possible variability between individuals resulting from genetic influences on the rate at which remodelling occurs may pose challenges to devising the appropriate regenerative therapy for a deaf patient.
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Affiliation(s)
- Ruth R Taylor
- Centre for Auditory Research, The Ear Institute, University College London, London, United Kingdom.
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Kuse H, Ogawa T, Nakamura N, Nakayama Y, Nakakarumai A, Komori C, Tsuda Y, Matsushima K, Nakamura A, Tamura K. Changes in auditory brainstem response (ABR) in Kanamycin-induced auditory disturbance model rats. J Toxicol Sci 2011; 36:835-41. [PMID: 22129748 DOI: 10.2131/jts.36.835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
This study was designed to evaluate changes in auditory brainstem response (ABR) in the course of auditory disturbance in rats induced by Kanamycin (KM). KM was administered subcutaneously to 12 CD (SD) male rats aged 6 weeks for 10 days at a dose of 800 mg/kg. Death was observed in one male on day 8 and 2 males on day 10. It was thought that kidney damage was the cause of death from histopathological findings. ABR was recorded before KM treatment and on days 4, 8, 10 and 11 after KM treatment. The ABR changes after KM treatment in rats were as follows. On day 4, 6 rats showed an increase in amplitude of waves I and/or II and on day 8, among those, 4 rats still showed a high amplitude of waves I and/or II. On day 8, 2 rats showed an elevation of ABR threshold (15-40 dB SPL) and a decrease in amplitude of wave I and increase in amplitude of wave II at the same time. On day 11, 7 rats showed a decrease in amplitude of wave I. In addition, ABR threshold shifts (10-70 dB SPL) were observed in those rats. In ABR recording, KM-induced auditory disturbance model rats showed an increase in amplitude of waves I and/or II earlier than an ABR threshold shift. By analyzing temporal alteration of amplitude of the ABR components, we could detect precursory phenomenon of the auditory disturbance at an early phase of treatment. By following the pathway of click-ABR and tone pip-ABR examination, the auditory disturbance of low- frequency to high-frequency range could be analyzed at an early date in detail.
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Crispino G, Di Pasquale G, Scimemi P, Rodriguez L, Galindo Ramirez F, De Siati RD, Santarelli RM, Arslan E, Bortolozzi M, Chiorini JA, Mammano F. BAAV mediated GJB2 gene transfer restores gap junction coupling in cochlear organotypic cultures from deaf Cx26Sox10Cre mice. PLoS One 2011; 6:e23279. [PMID: 21876744 PMCID: PMC3158073 DOI: 10.1371/journal.pone.0023279] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 07/11/2011] [Indexed: 11/24/2022] Open
Abstract
The deafness locus DFNB1 contains GJB2, the gene encoding connexin26 and GJB6, encoding connexin30, which appear to be coordinately regulated in the inner ear. In this work, we investigated the expression and function of connexin26 and connexin30 from postnatal day 5 to adult age in double transgenic Cx26(Sox10Cre) mice, which we obtained by crossing connexin26 floxed mice with a deleter Sox10-Cre line. Cx26(Sox10Cre) mice presented with complete connexin26 ablation in the epithelial gap junction network of the cochlea, whereas connexin30 expression was developmentally delayed; immunolabeling patterns for both connexins were normal in the cochlear lateral wall. In vivo electrophysiological measurements in Cx26(Sox10Cre) mice revealed profound hearing loss accompanied by reduction of endocochlear potential, and functional experiments performed in postnatal cochlear organotypic cultures showed impaired gap junction coupling. Transduction of these cultures with a bovine adeno associated virus vector restored connexin26 protein expression and rescued gap junction coupling. These results suggest that restoration of normal connexin levels by gene delivery via recombinant adeno associated virus could be a way to rescue hearing function in DFNB1 mouse models and, in future, lead to the development of therapeutic interventions in humans.
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Affiliation(s)
- Giulia Crispino
- Fondazione per la Ricerca Biomedica Avanzata, Istituto Veneto di Medicina Molecolare, Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, Padova, Italy
| | - Giovanni Di Pasquale
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Pietro Scimemi
- Dipartimento di Specialità Medico–Chirurgiche e Servizio di Audiologia, Università di Padova, Padova, Italy
| | - Laura Rodriguez
- Fondazione per la Ricerca Biomedica Avanzata, Istituto Veneto di Medicina Molecolare, Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, Padova, Italy
| | - Fabian Galindo Ramirez
- Fondazione per la Ricerca Biomedica Avanzata, Istituto Veneto di Medicina Molecolare, Padova, Italy
| | - Romolo Daniele De Siati
- Dipartimento di Specialità Medico–Chirurgiche e Servizio di Audiologia, Università di Padova, Padova, Italy
| | - Rosa Maria Santarelli
- Dipartimento di Specialità Medico–Chirurgiche e Servizio di Audiologia, Università di Padova, Padova, Italy
| | - Edoardo Arslan
- Dipartimento di Specialità Medico–Chirurgiche e Servizio di Audiologia, Università di Padova, Padova, Italy
| | - Mario Bortolozzi
- Fondazione per la Ricerca Biomedica Avanzata, Istituto Veneto di Medicina Molecolare, Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, Padova, Italy
- Istituto CNR di Neuroscienze, Padova, Italy
| | - John A. Chiorini
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Fabio Mammano
- Fondazione per la Ricerca Biomedica Avanzata, Istituto Veneto di Medicina Molecolare, Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, Padova, Italy
- Istituto CNR di Neuroscienze, Padova, Italy
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Gao SS, Xia A, Yuan T, Raphael PD, Shelton RL, Applegate BE, Oghalai JS. Quantitative imaging of cochlear soft tissues in wild-type and hearing-impaired transgenic mice by spectral domain optical coherence tomography. Opt Express 2011; 19:15415-28. [PMID: 21934905 PMCID: PMC3482885 DOI: 10.1364/oe.19.015415] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Human hearing loss often occurs as a result of damage or malformations to the functional soft tissues within the cochlea, but these changes are not appreciable with current medical imaging modalities. We sought to determine whether optical coherence tomography (OCT) could assess the soft tissue structures relevant to hearing using mouse models. We imaged excised cochleae with an altered tectorial membrane and during normal development. The soft tissue structures and expected anatomical variations were visible using OCT, and quantitative measurements confirmed the ability to detect critical changes relevant to hearing.
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Affiliation(s)
- Simon S. Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305,
USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005,
USA
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305,
USA
| | - Tao Yuan
- Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030,
USA
| | - Patrick D. Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305,
USA
| | - Ryan L. Shelton
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843
USA
| | - Brian E. Applegate
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843
USA
| | - John S. Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305,
USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005,
USA
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29
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Wang L, Bresee CS, Jiang H, He W, Ren T, Schweitzer R, Brigande JV. Scleraxis is required for differentiation of the stapedius and tensor tympani tendons of the middle ear. J Assoc Res Otolaryngol 2011; 12:407-21. [PMID: 21399989 DOI: 10.1007/s10162-011-0264-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 02/22/2011] [Indexed: 12/20/2022] Open
Abstract
Scleraxis (Scx) is a basic helix-loop-helix transcription factor expressed in tendon and ligament progenitor cells and the differentiated cells within these connective tissues in the axial and appendicular skeleton. Unexpectedly, we found expression of the Scx transgenic reporter mouse, Scx-GFP, in interdental cells, sensory hair cells, and cochlear supporting cells at embryonic day 18.5 (E18.5). We evaluated Scx-null mice to gain insight into the function of Scx in the inner ear. Paradoxical hearing loss was detected in Scx-nulls, with ~50% of the mutants presenting elevated auditory thresholds. However, Scx-null mice have no obvious, gross alterations in cochlear morphology or cellular patterning. Moreover, we show that the elevated auditory thresholds correlate with middle ear infection. Laser interferometric measurement of sound-induced malleal movements in the infected Scx-nulls demonstrates increased impedance of the middle ear that accounts for the hearing loss observed. The vertebrate middle ear transmits vibrations of the tympanic membrane to the cochlea. The tensor tympani and stapedius muscles insert into the malleus and stapes via distinct tendons and mediate the middle ear muscle reflex that in part protects the inner ear from noise-induced damage. Nothing, however, is known about the development and function of these tendons. Scx is expressed in tendon progenitors at E14.5 and differentiated tenocytes of the stapedius and tensor tympani tendons at E16.5-18.5. Scx-nulls have dramatically shorter stapedius and tensor tympani tendons with altered extracellular matrix consistent with abnormal differentiation in which condensed tendon progenitors are inefficiently incorporated into the elongating tendons. Scx-GFP is the first transgenic reporter that identifies middle ear tendon lineages from the time of their formation through complete tendon maturation. Scx-null is the first genetically defined mouse model for abnormal middle ear tendon differentiation. Scx mouse models will facilitate studies of tendon and muscle formation and function in the middle ear.
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Affiliation(s)
- Lingyan Wang
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, USA.
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30
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Schütz M, Scimemi P, Majumder P, De Siati RD, Crispino G, Rodriguez L, Bortolozzi M, Santarelli R, Seydel A, Sonntag S, Ingham N, Steel KP, Willecke K, Mammano F. The human deafness-associated connexin 30 T5M mutation causes mild hearing loss and reduces biochemical coupling among cochlear non-sensory cells in knock-in mice. Hum Mol Genet 2010; 19:4759-73. [PMID: 20858605 PMCID: PMC2989887 DOI: 10.1093/hmg/ddq402] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/18/2010] [Accepted: 09/14/2010] [Indexed: 12/11/2022] Open
Abstract
Mutations in the GJB2 and GJB6 genes, respectively, coding for connexin26 (Cx26) and connexin30 (Cx30) proteins, are the most common cause for prelingual non-syndromic deafness in humans. In the inner ear, Cx26 and Cx30 are expressed in different non-sensory cell types, where they largely co-localize and may form heteromeric gap junction channels. Here, we describe the generation and characterization of a mouse model for human bilateral middle/high-frequency hearing loss based on the substitution of an evolutionarily conserved threonine by a methionine residue at position 5 near the N-terminus of Cx30 (Cx30T5M). The mutation was inserted in the mouse genome by homologous recombination in mouse embryonic stem cells. Expression of the mutated Cx30T5M protein in these transgenic mice is under the control of the endogenous Cx30 promoter and was analysed via activation of the lacZ reporter gene. When probed by auditory brainstem recordings, Cx30(T5M/T5M) mice exhibited a mild, but significant increase in their hearing thresholds of about 15 dB at all frequencies. Immunolabelling with antibodies to Cx26 or Cx30 suggested normal location of these proteins in the adult inner ear, but western blot analysis showed significantly down-regulated the expression levels of Cx26 and Cx30. In the developing cochlea, electrical coupling, probed by dual patch-clamp recordings, was normal. However, transfer of the fluorescent tracer calcein between cochlear non-sensory cells was reduced, as was intercellular Ca(2+) signalling due to spontaneous ATP release from connexin hemichannels. Our findings link hearing loss to decreased biochemical coupling due to the point-mutated Cx30 in mice.
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Affiliation(s)
- Melanie Schütz
- Institut fuer Genetik, Rheinische Friedrich-Wilhelms-Universitaet Bonn, Roemerstrasse 164, D-53117 Bonn, Germany
| | - Pietro Scimemi
- Dipartimento di Specialità Medico Chirurgiche, Università di Padova, via Giustiniani 2, 35129 Padova, Italy
- Servizio di Audiologia, Ospedale ‘Ca’ Foncello’, Treviso, Italy
| | - Paromita Majumder
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Romolo Daniele De Siati
- Dipartimento di Specialità Medico Chirurgiche, Università di Padova, via Giustiniani 2, 35129 Padova, Italy
- Servizio di Audiologia, Ospedale ‘Ca’ Foncello’, Treviso, Italy
| | - Giulia Crispino
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Laura Rodriguez
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Mario Bortolozzi
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Dipartimento di Fisica ‘G. Galilei’, Università di Padova, 35131 Padova, Italy
- Istituto CNR di Neuroscienze, Padova, Italy and
| | - Rosamaria Santarelli
- Dipartimento di Specialità Medico Chirurgiche, Università di Padova, via Giustiniani 2, 35129 Padova, Italy
- Servizio di Audiologia, Ospedale ‘Ca’ Foncello’, Treviso, Italy
| | - Anke Seydel
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Stephan Sonntag
- Institut fuer Genetik, Rheinische Friedrich-Wilhelms-Universitaet Bonn, Roemerstrasse 164, D-53117 Bonn, Germany
| | - Neil Ingham
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Karen P. Steel
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Klaus Willecke
- Institut fuer Genetik, Rheinische Friedrich-Wilhelms-Universitaet Bonn, Roemerstrasse 164, D-53117 Bonn, Germany
| | - Fabio Mammano
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Dipartimento di Fisica ‘G. Galilei’, Università di Padova, 35131 Padova, Italy
- Istituto CNR di Neuroscienze, Padova, Italy and
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Motohashi R, Takumida M, Shimizu A, Konomi U, Fujita K, Hirakawa K, Suzuki M, Anniko M. Effects of age and sex on the expression of estrogen receptor alpha and beta in the mouse inner ear. Acta Otolaryngol 2010; 130:204-14. [PMID: 19479455 DOI: 10.3109/00016480903016570] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION Estrogen receptor (ER) alpha and beta were expressed in the inner ear, and expression decreased with increasing age. ERalpha may alter cochlear and vestibular sensory transduction, and ERbeta may have a neuroprotective function in the inner ear. OBJECTIVE Expression of ERalpha and ERbeta in the mouse inner ear and its alterations with sex and aging were analyzed. MATERIALS AND METHODS Male and female CBA/J mice aged 8 weeks and 24 months were used. The localization and the intensity of ERalpha and ERbeta immunoreactivity in the inner ear of young and old mice of both sexes were investigated by immunohistochemistry. RESULTS ERalpha and ERbeta were co-expressed in the inner ear, i.e. in the nuclei of stria vascularis, outer and inner hair cells, spiral ganglion cells and vestibular ganglion cells, vestibular dark cells and endolymphatic sac. Strial marginal cells, outer hair cells and type II ganglion cells showed less expression of ERalpha. No gender- or age-related difference was noted in the expression pattern of ERalpha or ERbeta, but fluorescence intensity of ERalpha was stronger in young female mice than in young male mice. In contrast, ERbeta revealed no significant difference. In the old mice, fluorescence intensities of both ERalpha and ERbeta were significantly decreased in both sexes.
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MESH Headings
- Age Factors
- Aging/physiology
- Animals
- Atrophy/metabolism
- Atrophy/pathology
- Ear, Inner/cytology
- Ear, Inner/metabolism
- Ear, Inner/physiology
- Endolymphatic Sac/cytology
- Endolymphatic Sac/metabolism
- Estrogen Receptor alpha/metabolism
- Estrogen Receptor beta/metabolism
- Female
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/pathology
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/pathology
- Immunohistochemistry
- Male
- Mice
- Mice, Inbred CBA
- Microscopy, Fluorescence
- Organ of Corti/metabolism
- Organ of Corti/pathology
- Sex Factors
- Spiral Ganglion/cytology
- Spiral Ganglion/metabolism
- Spiral Ganglion/pathology
- Stria Vascularis/cytology
- Stria Vascularis/metabolism
- Stria Vascularis/pathology
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Affiliation(s)
- Ray Motohashi
- Department of Otolaryngology, Tokyo Medical University, Tokyo 160-0023, Japan.
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Zolotova TV, Panchenko SN. [Experimental sensorineural loss of hearing of ototoxic origin in animals: apoptotic mechanism of cell death in the spiral organ]. Vestn Otorinolaringol 2010:29-32. [PMID: 21105341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This morphological study was carried out using white rats with experimental sensorineural loss of hearing. A method for simulation of ototoxic loss of hearing in laboratory animals is proposed. Investigations with the use of light microscopy revealed elements of the apoptotic mechanism of cell death in the spiral organ of rats with sensorineural loss of hearing. It was shown that application of methods designed to influence the mechanisms involved in regulation of apoptosis in animals with experimental sensorineural loss of hearing either prevents or decreases the death of neuroepithelial and auxiliary cells of the spiral organ.
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Izquierdo MA, Oliver DL, Malmierca MS. [Functional and activity-dependent plasticity mechanisms in the adult and developing auditory brain]. Rev Neurol 2009; 48:421-429. [PMID: 19340783 PMCID: PMC2916753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
INTRODUCTION AND DEVELOPMENT Sensory systems show a topographic representation of the sensory epithelium in the central nervous system. In the auditory system this representation originates tonotopic maps. For the last four decades these changes in tonotopic maps have been widely studied either after peripheral mechanical lesions or by exposing animals to an augmented acoustic environment. These sensory manipulations induce plastic reorganizations in the tonotopic map of the auditory cortex. By contrast, acoustic trauma does not seem to induce functional plasticity at subcortical nuclei. Mechanisms that generate these changes differ in their molecular basis and temporal course and we can distinguish two different mechanisms: those involving an active reorganization process, and those that show a simple reflection of the loss of peripheral afferences. Only the former involve a genuine process of plastic reorganization. Neuronal plasticity is critical for the normal development and function of the adult auditory system, as well as for the rehabilitation needed after the implantation of auditory prostheses. However, development of plasticity can also generate abnormal sensation like tinnitus. Recently, a new concept in neurobiology so-called ‘neuronal stability’ has emerged and its implications and conceptual basis could help to improve the treatments of hearing loss. CONCLUSION A combination of neuronal plasticity and stability is suggested as a powerful and promising future strategy in the design of new treatments of hearing loss.
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Affiliation(s)
- M A Izquierdo
- Departamento de Biología Celular y Patología, Facultad de Medicina, Unidad de Neurofisiología de la Audición, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, España
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Affiliation(s)
- Kevin K Ohlemiller
- Fay and Carl Simons Center for the Biology of Hearing and Deafness, Central Institute for the Deaf at Washington University, Department of Otolaryngology, Washington University Medical School, St. Louis, MO 63110, USA.
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Cotanche DA. Genetic and pharmacological intervention for treatment/prevention of hearing loss. J Commun Disord 2008; 41:421-443. [PMID: 18455177 PMCID: PMC2574670 DOI: 10.1016/j.jcomdis.2008.03.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 03/12/2008] [Indexed: 05/26/2023]
Abstract
UNLABELLED Twenty years ago it was first demonstrated that birds could regenerate their cochlear hair cells following noise damage or aminoglycoside treatment. An understanding of how this structural and functional regeneration occurred might lead to the development of therapies for treatment of sensorineural hearing loss in humans. Recent experiments have demonstrated that noise exposure and aminoglycoside treatment lead to apoptosis of the hair cells. In birds, this programmed cell death induces the adjacent supporting cells to undergo regeneration to replace the lost hair cells. Although hair cells in the mammalian cochlea undergo apoptosis in response to noise damage and ototoxic drug treatment, the supporting cells do not possess the ability to undergo regeneration. However, current experiments on genetic manipulation, gene therapy, and stem cell transplantation suggest that regeneration in the mammalian cochlea may eventually be possible and may 1 day provide a therapeutic tool for hearing loss in humans. LEARNING OUTCOMES The reader should be able to: (1) Describe the anatomy of the avian and mammalian cochlea, identify the individual cell types in the organ of Corti, and distinguish major features that participate in hearing function, (2) Demonstrate a knowledge of how sound damage and aminoglycoside poisoning induce apoptosis of hair cells in the cochlea, (3) Define how hair cell loss in the avian cochlea leads to regeneration of new hair cells and distinguish this from the mammalian cochlea where there is no regeneration following damage, and (4) Interpret the potential for new approaches, such as genetic manipulation, gene therapy and stem cell transplantation, could provide a therapeutic approach to hair cell loss in the mammalian cochlea.
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MESH Headings
- Aminoglycosides/toxicity
- Animals
- Apoptosis/drug effects
- Apoptosis/genetics
- Apoptosis/physiology
- Birds
- Cell Proliferation/drug effects
- Genetic Therapy
- Guinea Pigs
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/pathology
- Hair Cells, Auditory/physiology
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Noise-Induced/therapy
- Hearing Loss, Sensorineural/pathology
- Hearing Loss, Sensorineural/physiopathology
- Hearing Loss, Sensorineural/therapy
- Humans
- Mice
- Mice, Knockout
- Microscopy, Confocal
- Nerve Regeneration/drug effects
- Nerve Regeneration/genetics
- Nerve Regeneration/physiology
- Organ of Corti/drug effects
- Organ of Corti/pathology
- Organ of Corti/physiopathology
- Stem Cell Transplantation
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Affiliation(s)
- Douglas A Cotanche
- Laboratory of Cellular and Molecular Hearing Research, Department of Otolaryngology, Children's Hospital Boston, Boston, MA, USA.
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36
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Kim SJ, Jeong HJ, Myung NY, Kim MC, Lee JH, So HS, Park RK, Kim HM, Um JY, Hong SH. The protective mechanism of antioxidants in cadmium-induced ototoxicity in vitro and in vivo. Environ Health Perspect 2008; 116:854-62. [PMID: 18629305 PMCID: PMC2453151 DOI: 10.1289/ehp.10467] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Accepted: 02/25/2008] [Indexed: 05/20/2023]
Abstract
BACKGROUND Several heavy metals have been shown to have toxic effects on the peripheral and central auditory system. Cadmium (Cd2+) is an environmental contaminant showing a variety of adverse effects. Given the current rate of release into the environment, the amount of Cd2+ present in the human body and the incidence of Cd2+-related diseases are expected to increase. OBJECTIVE The overall aim of this study was to gain further insights into the mechanism of Cd2+-induced ototoxicity. METHODS Cell viability, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), cytochrome c (cyt c), phosphorylated extracellular signal-regulated protein kinase (p-ERK), caspases, morphologic change, and functional changes in HEI-OC1 cells, rat cochlear explants, and mouse cochlea after Cd2+ exposure were measured by flow cytometry, immunohistochemical staining, Western blot analysis, and auditory brainstem response (ABR) recording. Mechanisms underlying Cd2+ototoxicity were studied using inhibitors of different signaling pathways, caspases, and antioxidants. RESULTS Cd2+ exposure caused cell death, ROS generation, MMP loss, cyt c release, activation of caspases, ERK activation, apoptosis, and finally auditory threshold shift. Cd2+ toxicity interfered with inhibitors of cellular signaling pathways, such as ERK and c-jun N-terminal kinase, and with caspase inhibitors, especially inhibitors of caspase-9 and caspase-3. The antioxidants N-acetyl-l-cysteine and ebselen showed a significant protective effect on the Cd2+ toxicity. CONCLUSIONS Cd2+ is ototoxic with a complex underlying mechanism. However, ROS generation may be the cause of the toxicity, and application of antioxidants can prevent the toxic effect.
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Affiliation(s)
- Su-Jin Kim
- College of Oriental Medicine, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul, Republic of Korea
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Hyun-Ja Jeong
- College of Oriental Medicine, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul, Republic of Korea
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Noh-Yil Myung
- College of Oriental Medicine, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul, Republic of Korea
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Min-chol Kim
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Jeong-Han Lee
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Hong-seob So
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Rae-Kil Park
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
| | - Hyung-Min Kim
- College of Oriental Medicine, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul, Republic of Korea
| | - Jae-Young Um
- College of Oriental Medicine, Kyung Hee University, Hoegi-Dong, Dongdaemun-Gu, Seoul, Republic of Korea
| | - Seung-Heon Hong
- Vestibulocochlear Research Center of Wonkwang University, Iksan, Jeonbuk, Republic of Korea
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37
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Chen GD, Tanaka C, Henderson D. Relation between outer hair cell loss and hearing loss in rats exposed to styrene. Hear Res 2008; 243:28-34. [PMID: 18586423 DOI: 10.1016/j.heares.2008.05.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 04/24/2008] [Accepted: 05/08/2008] [Indexed: 11/19/2022]
Abstract
The relationship between outer hair cell (OHC) loss and cochlear sensitivity is still unclear, because in many animal models there exist surviving but dysfunctional OHCs and also injured/dead inner hair cells (IHC). Styrene is an ototoxic agent, which targets and destroys OHCs starting from the third row to the second and first rows depending on the exposure level. The remaining cells may be less affected. In this experiment, rats were exposed to styrene by gavage at different doses (200-800 mg/kg/day) for varying periods (5 days/week for 3-12 weeks). An interesting finding was that the cochlear sensitivity was not affected in a few rats with all OHCs in the third row being destroyed by styrene. A further loss of OHCs was usually accompanied with a linear input/output (I/O) function of cochlear compound action potentials (CAP), indicating the loss of cochlear amplification. However, normal CAP amplitudes at the highest stimulation level of 90 dB SPL were often observed when all OHCs were destroyed, indicating normal function of the remaining IHCs. The OHC-loss/hearing-loss relation appeared to be a sigmoid-type function. Initially, styrene-induced OHC losses (<33%) did not result in a significant threshold shift. Then CAP threshold shift increased dramatically with OHC loss from 33% to 66%. Then, CAP threshold changed less with OHC loss. The data suggest a tri-modal relationship between OHC loss and cochlear amplification. That is, under the condition that all surviving OHCs are ideally functioning, the cochlear amplifier is not affected until 33% of OHCs are absent, then the gain of the amplifier decreases proportionally with the OHC loss, and at last the amplifier may fail completely when more than 67% of OHCs are lost.
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Affiliation(s)
- Guang-Di Chen
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA.
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38
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Engström H, Ades HW, Bredberg G. Normal structure of the organ of Corti and the effect of noise-induced cochlear damage. In: Sensorineural hearing loss. Ciba Found Symp 2008:127-56. [PMID: 4943822 DOI: 10.1002/9780470719756.ch8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
HYPOTHESIS Severe spiral ganglion cell loss does not necessarily follow loss of hair cells or supporting cells in humans. BACKGROUND Despite some publications to the contrary, statements that loss of hair cells and/or supporting cells of the organ of Corti results in a severe loss of spiral ganglion cells in humans still appear in the literature, especially in respect to cochlear implants. This assumption is apparently based on studies in animals or cell culture and not from studies of human temporal bones. METHODS Morphological analysis of archival temporal bones with microscopic and statistical analysis of ganglion cell, hair cell, and supporting cell populations was performed in 33 ears with total hearing losses of varying causes and durations of deafness. None of the ears had remaining hair cells. Six ears had had cochlear implants. RESULTS Ganglion cell counts ranging from 2,889 to 34,299 and the corresponding percentage of remaining ganglion cells based on age-normative data were not significantly related to the duration of hearing loss (r = -0.13 and 0.02, respectively, p > 0.05) or to remaining supporting cell populations (r's from 0.15 to 0.27, p > 0.05). More than half of ears (51.5%) had ganglion cell counts within two standard deviations of age-normative means. Mean ganglion cell counts and percentage of remaining ganglion cells of ears with surviving peripheral processes (dendrites) did not differ significantly from those of ears with no peripheral processes. CONCLUSION The loss of hair and supporting cells in the organ of Corti in humans does not necessarily result in as significant a loss of spiral ganglion cells as has been reported animals. In fact, our results suggest that ganglion cell loss may be a primary concomitant loss due to the disease process.
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Affiliation(s)
- Karen Borne Teufert
- Histopathology Department, House Ear Institute, Los Angeles, California 90057, USA.
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40
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Huang CQ, Tykocinski M, Stathopoulos D, Cowan R. Effects of steroids and lubricants on electrical impedance and tissue response following cochlear implantation. Cochlear Implants Int 2008; 8:123-47. [PMID: 17854099 DOI: 10.1179/cim.2007.8.3.123] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The present study examined the effects of steroids and lubricants on electrical impedance and tissue response following cochlear implantation in animal models. Guinea pigs were implanted following either no treatment, or intrascalar injection with dexamethasone, triamcinolone, sodium hyaluronate or saline. Cats were implanted following either no treatment, or intrascalar injection with dexamethasone, triamcinolone or a mixture of triamcinolone with sodium hyaluronate. In guinea pigs, impedance changes and intracochlear tissue response were less for the hyaluronate and saline groups. In cats, impedance in the dexamethasone group increased similar to non-treated cats. Impedance of triamcinolone treated cats remained low for about two months after implantation, before increasing to levels similar to the other groups. Significant fibrous tissue growth was observed histologically. The results of the present study indicate that a single intracochlear application of hyaluronate or triamcinolone may postpone, but will ultimately not prevent the rise in impedance following cochlear implantation.
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Affiliation(s)
- Christie Qi Huang
- Co-operative Research Centre for Cochlear Implant and Hearing Aid Innovation, Melbourne, Victoria, Australia
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41
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Abstract
Transdifferentiation of nonsensory supporting cells into sensory hair cells occurs naturally in the damaged avian inner ear. Such transdifferentiation was achieved experimentally in the cochlea of deaf guinea pigs through Atoh 1 gene transfection. Supporting cells may therefore serve as targets for transdifferentiation therapy. Supporting cells rapidly degenerate after hair cell disappearance, however, limiting the therapeutic window for gene transfer. We studied the time course of ultrastructural and phenotypical changes occurring in Deiters cells (hair cell supporting cells) after ototoxic treatment in the rat. The presence of macrophages in the cochlea was also investigated, to study any deleterious effects they may have on pathologic tissues. One week after treatment most hair cells had disappeared. Deiters cells no longer expressed the glial marker vimentin but instead displayed typical hair cell markers, the calcium binding proteins calbindin and parvalbumin. This suggests that a process of transdifferentiation of Deiters cells into hair cells was activated. By 3 weeks post-treatment, however, the Deiters cells began to degenerate and by 10 weeks post-treatment the organ of Corti was degraded fully. Interestingly, a marked increase in macrophage density was seen after the end of amikacin treatment to 10 weeks post-treatment. This suggests chronic inflammation is involved in epithelium degeneration. Consequently, early treatments with anti-inflammatory factors might promote supporting cell survival, thus improving the efficacy of more specific strategies aimed to regenerate hair cells from nonsensory cells.
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Affiliation(s)
- Sabine Ladrech
- INSERM, U.583, Laboratoire de Physiopathologie et Thérapie des Déficits Sensoriels et Moteurs, Montpellier, France
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Abstract
OBJECTIVES Otoacoustic emissions (OAEs), discovered in 1978, have a well-established cochlear origin. They strongly depend on the outer hair cells and are widely used in experimental research as a means for testing cochlear function. However, outside screening, OAEs are only rarely used in clinical practice. The objective of this paper was to show their vast clinical utility. MATERIAL AND METHODS First, a review of the biophysical and physiological knowledge on OAEs is provided, concerning transient OAEs as well as distortion-product OAEs, recalling the origin and the meanings of these acoustic signals. Several clinical situations are then presented, and the corresponding OAE alterations are explained, such as hearing screening in neonates, diagnosis of hearing impairment with particularities related to the age of the patient, situations critical to the cochlea such as ototoxic treatments, and surgical procedures to the cerebellopontine angle. RESULTS OAEs appear to be a powerful tool in clinical practice, particularly in hearing screening and diagnosis of deafness. They can also be used to monitor hearing function during cerebellopontine angle tumor resection. CONCLUSION OAEs are still rarely used as a diagnostic tool by clinicians despite their clinical value, which should make them a primary choice.
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Affiliation(s)
- T Mom
- Service d'ORL et de Chirurgie Cervicofaciale, Hôpital Gabriel-Montpied, Université Clermont-Ferrand-I, 63000 Clermont-Ferrand, France.
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43
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Abstract
BACKGROUND Mohr-Tranebjaerg syndrome (MTS) is an X-linked, recessive, syndromic sensorineural hearing loss (HL) characterized by onset of deafness in childhood followed later in adult life by progressive neural degeneration affecting the brain and optic nerves. MTS is caused by mutations in the DDP/TIMM8A gene, which encodes for a 97 amino acid polypeptide; this polypeptide is a translocase of the inner mitochondrial membrane. OBJECTIVES To describe the otologic presentation and temporal bone histopathology in four affected individuals with MTS. MATERIAL AND METHODS All four subjects belonged to a large, multigenerational Norwegian family and were known to carry a frame shift mutation in the TIMM8A gene. Temporal bones were removed at autopsy and studied by light microscopy. Cytocochleograms were constructed for hair cells, stria vascularis, and cochlear neuronal cells. Vestibular neurons were also counted. RESULTS All four subjects developed progressive HL in early childhood, becoming profoundly deaf by the age of 10 years. All four developed language, and at least one subject used amplification in early life. Audiometric evaluation in two subjects showed 80- to 100-dB HL by the age of 10 years. The subjects died between the ages of 49 and 67. The otopathology was strikingly similar in that all bones examined showed near-total loss of cochlear neuronal cells and severe loss of vestibular neurons. When compared with age-matched controls, there was 90% to 95% loss of cochlear neurons and 75% to 85% loss of vestibular neurons. CONCLUSIONS We infer that the HL in MTS is likely to be the result of a postnatal and progressive degeneration of cochlear neurons and that MTS constitutes a true auditory neuropathy. Our findings have implications for clinical diagnosis of patients with MTS and management of the HL.
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Affiliation(s)
- Fayez Bahmad
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Saumil N. Merchant
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Joseph B. Nadol
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Lisbeth Tranebjærg
- Department of Audiology, Bispebjerg Hospital, Wilhelm Johannsen Centre of Functional Genomics, Institute for Molecular and Cellular Medicine, The Panum Institute, Copenhagen, Denmark; and Department of Medical Genetics, University Hospital, N-Tromsø, Norway
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44
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Selivanova O, Brieger J, Heinrich UR, Mann W. Akt and c-Jun N-terminal kinase are regulated in response to moderate noise exposure in the cochlea of guinea pigs. ORL J Otorhinolaryngol Relat Spec 2007; 69:277-82. [PMID: 17565230 DOI: 10.1159/000103871] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 02/27/2007] [Indexed: 11/19/2022]
Abstract
The molecular mechanisms induced in the inner ear after noise exposure are not well understood. Akt and c-Jun N-terminal kinase (JNK) are key factors of signaling pathways balancing cellular survival and apoptosis. Therefore, we analyzed the spatial distribution of Akt, JNK, their respective activated (i.e. phosphorylated) forms, p-Akt and p-JNK, as well as NF kappa B by immunohistochemistry after 70- and 90-dB noise exposure in an animal model. Alterations of the expression patterns compared to unexposed animals were quantified by a computer-based image analysis method. In unexposed specimens, Akt, p-Akt, JNK, p-JNK were found to be commonly expressed in different regions of the cochlea, whereas NF kappa B was exclusively restricted to the lateral wall. After noise stimulation, the expression of the different molecules was downregulated with the exception of JNK. JNK remained largely unchanged or increased JNK levels were identified in ganglion cells and Schwann cells after 70 dB as well as in the unstained nerve fibers. The stable or increasing levels of JNK might be indicative of a preapoptotic state. The downregulation of Akt in the cochlea might support these activities. p-Akt was not reduced in the spiral ganglion cells after 90-dB exposure and was upregulated in the unstained nerve fibers, probably indicating a counteracting prosurvival cellular reaction in these tissues. In conclusion, we suggest that the observed alterations in both the Akt and JNK pathways are part of a noise distress-induced response indicating pro- and antiapoptotic activities in the different tissues of the cochlea.
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Affiliation(s)
- Oxana Selivanova
- Department of Otorhinolaryngology, Mainz Medical School, Mainz, Germany
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45
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Abstract
The relationship between meningitis and sensorineural hearing loss (SNHL) has long been studied. Many histopathological studies of animal models and human temporal bones with respect to bacterial meningitis have been carried out. However, the relationship between SNHL and tuberculous meningitis was seldom addressed and the pathophysiology remains unclear. We carried out temporal bone studies on material from a 22-year-old patient who developed a right unilateral SNHL before dying from tuberculous meningitis. The histopathological findings for the right temporal bone were as follows: (1) inflammation mainly appeared in the internal auditory canal, modiolus and Rosenthal's canal and extended to the osseous spiral ligament, whereas the perilymphatic spaces were less involved; (2) the organ of Corti, cochlear nerve fibres and spiral ganglion cells were severely degenerated, particularly in the basal and middle turns; (3) the contralateral side (for which the patient had no complaints) showed an inner space free from inflammation, but some granulomatous formations were observed in the middle ear cavity. We conclude that the modiolus and cochlear aqueduct are the main routes for the spread of infection from the meninges to the inner ear. The progression of hearing loss resembles that of bacterial meningitis and shares attributes of retrocochlear SNHL.
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Affiliation(s)
- Chen-Chieh Kuan
- Department of Otolaryngology and Head and Neck Surgery, Faculty of Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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46
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Herr DR, Grillet N, Schwander M, Rivera R, Müller U, Chun J. Sphingosine 1-phosphate (S1P) signaling is required for maintenance of hair cells mainly via activation of S1P2. J Neurosci 2007; 27:1474-8. [PMID: 17287522 PMCID: PMC6673597 DOI: 10.1523/jneurosci.4245-06.2007] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hearing requires the transduction of vibrational forces by specialized epithelial cells in the cochlea known as hair cells. The human ear contains a finite number of terminally differentiated hair cells that, once lost by noise-induced damage or toxic insult, can never be regenerated. We report here that sphingosine 1-phosphate (S1P) signaling, mainly via activation of its cognate receptor S1P2, is required for the maintenance of vestibular and cochlear hair cells in vivo. Two S1P receptors, S1P2 and S1P3, were found to be expressed in the cochlea by reverse transcription-PCR and in situ hybridization. Mice that are null for both these receptors uniformly display progressive cochlear and vestibular defects with hair cell loss, resulting in complete deafness by 4 weeks of age and, with complete penetrance, balance defects of increasing severity. This study reveals the previously unknown role of S1P signaling in the maintenance of cochlear and vestibular integrity and suggests a means for therapeutic intervention in degenerative hearing loss.
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MESH Headings
- Acoustic Stimulation
- Aging/pathology
- Animals
- Cell Survival
- Cochlea/growth & development
- Cochlea/metabolism
- Cochlea/pathology
- Cochlea/physiopathology
- Deafness/genetics
- Deafness/pathology
- Exploratory Behavior
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/physiology
- Hair Cells, Vestibular/cytology
- Hair Cells, Vestibular/physiology
- Hearing/physiology
- In Situ Hybridization
- Lysophospholipids
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nerve Degeneration/metabolism
- Nerve Degeneration/pathology
- Organ of Corti/metabolism
- Organ of Corti/pathology
- Postural Balance/physiology
- Receptors, Lysosphingolipid/biosynthesis
- Receptors, Lysosphingolipid/deficiency
- Receptors, Lysosphingolipid/genetics
- Receptors, Lysosphingolipid/physiology
- Reflex, Startle
- Reverse Transcriptase Polymerase Chain Reaction
- Sensation Disorders/genetics
- Sensation Disorders/pathology
- Sphingosine/analogs & derivatives
- Sphingosine-1-Phosphate Receptors
- Spiral Ganglion/metabolism
- Spiral Ganglion/pathology
- Vestibule, Labyrinth/metabolism
- Vestibule, Labyrinth/pathology
- Vestibule, Labyrinth/physiopathology
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Affiliation(s)
- Deron R. Herr
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, and
| | - Nicolas Grillet
- Department of Cell Biology, Institute for Childhood and Neglected Disease, The Scripps Research Institute, La Jolla, California 92037
| | - Martin Schwander
- Department of Cell Biology, Institute for Childhood and Neglected Disease, The Scripps Research Institute, La Jolla, California 92037
| | - Richard Rivera
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, and
| | - Ulrich Müller
- Department of Cell Biology, Institute for Childhood and Neglected Disease, The Scripps Research Institute, La Jolla, California 92037
| | - Jerold Chun
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, and
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47
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Abstract
CONCLUSION The circling mouse (cir/cir) has phenotypes which follow the pattern of neuroepithelial defects of deafness from 10 days after birth. The cir mouse is defective in Tmie gene, the function of which should be further elucidated. OBJECTIVES We previously reported a recessive mutation of deafness called circling mice (cir/cir). The present study focused on investigating phenotypes and histological findings of the cochlea in circling mice with respect to age. MATERIALS AND METHODS In order to analyze cochlear pathology over time, five different age groups of circling mice were examined (10, 18, 21, 35, and 90 days old). The organs of Corti and spiral ganglion neurons in basal and middle turns were evaluated. RESULTS The pathology of the organ of Corti followed the pattern of neuroepithelial defects. Hair cells in organs of Corti had degenerated in circling mice at 10 days old, in a time-dependent manner. Scanning electron microscopy (SEM) showed that stereociliary bundles were irregular in size and had shortened at 10 days, and that this degeneration was complete at 21 days. The number of spiral ganglion neurons significantly reduced with age. RT-PCR analysis indicated that the transmembrane inner ear gene (Tmie) was absent in various organs in circling mice.
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Affiliation(s)
- Won-Ho Chung
- Department of Otorhinolaryngology-Head and Neck Surgery, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul
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48
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Mostafa BE, Tawfik S, Hefnawi NGE, Hassan MA, Ismail FA. The role of deferoxamine in the prevention of gentamicin ototoxicity: a histological and audiological study in guinea pigs. Acta Otolaryngol 2007; 127:234-9. [PMID: 17364358 DOI: 10.1080/00016480600794495] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
CONCLUSION The addition of deferoxamine to gentamicin seems to confer partial functional and histological protection to the cochlea. OBJECTIVE Aminoglycosides are known ototoxic agents. The toxicity occurs via an activation process involving the formation of an iron-gentamicin complex with free radical production. Iron chelation will supposedly limit this toxic effect. This study aimed to determine the possible cochleoprotective role of deferoxamine on the ototoxic effect of gentamicin. MATERIALS AND METHODS Sixty healthy active guinea pigs, weighing 400-600 g, with an average age of 6 months were used. They were divided into three groups. Group 1 received intramuscular gentamicin 8 mg/kg/day, group 2 received gentamicin 8 mg/kg/day and deferoxamine 150 mg/kg twice daily for 19 days and group 3 served as a control. All animals had a baseline measurement of distortion product oto-acoustic emissions. At the end of 33 days they were submitted to another measurement and then the animals were sacrificed and their cochleas were examined histologically by light and transmission electron microscopy. RESULTS In group 1 the mean amplitude post-injection ranged from 5.83 dB at 1001 Hz to 22.33 dB at 6348 Hz. In the deferoxamine + gentamicin group the mean amplitude post-injection ranged from 5.10 dB at 1001 Hz, to 24.45 dB at 6348 Hz. This was statistically significant. At 4004, 5042 and 6348 Hz group 2 showed less histological damage than group 1.
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MESH Headings
- Animals
- Cell Survival/physiology
- Cochlea/drug effects
- Cochlea/pathology
- Cochlea/physiopathology
- Deferoxamine/pharmacology
- Gentamicins/antagonists & inhibitors
- Gentamicins/toxicity
- Guinea Pigs
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/pathology
- Hair Cells, Auditory, Inner/physiopathology
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/pathology
- Hair Cells, Auditory, Outer/physiopathology
- Injections, Intramuscular
- Iron Chelating Agents/pharmacology
- Microscopy, Electron, Scanning
- Organ of Corti/drug effects
- Organ of Corti/pathology
- Organ of Corti/physiopathology
- Otoacoustic Emissions, Spontaneous/drug effects
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Affiliation(s)
- Badr Eldin Mostafa
- Department of Otorhinolaryngology, Ain-Shams Faculty of Medicine, Cairo, Egypt.
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49
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Laine H, Doetzlhofer A, Mantela J, Ylikoski J, Laiho M, Roussel MF, Segil N, Pirvola U. p19(Ink4d) and p21(Cip1) collaborate to maintain the postmitotic state of auditory hair cells, their codeletion leading to DNA damage and p53-mediated apoptosis. J Neurosci 2007; 27:1434-44. [PMID: 17287518 PMCID: PMC6673588 DOI: 10.1523/jneurosci.4956-06.2007] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 12/22/2006] [Accepted: 12/22/2006] [Indexed: 11/21/2022] Open
Abstract
Sensory hair cells of the auditory organ are generated during embryogenesis and remain postmitotic throughout life. Previous work has shown that inactivation of the cyclin-dependent kinase inhibitor (CKI) p19(Ink4d) leads to progressive hearing loss attributable to inappropriate DNA replication and subsequent apoptosis of hair cells. Here we show the synergistic action of another CKI, p21(Cip1), on cell cycle reactivation. The codeletion of p19(Ink4d) and p21(Cip1) triggered profuse S-phase entry of auditory hair cells during a restricted period in early postnatal life, leading to the transient appearance of supernumerary hair cells. In addition, we show that aberrant cell cycle reentry leads to activation of a DNA damage response pathway in these cells, followed by p53-mediated apoptosis. The majority of hair cells were absent in adult cochleas. These data, together with the demonstration of changing expression patterns of multiple CKIs in auditory hair cells during the stages of early postnatal maturation, show that the maintenance of the postmitotic state is an active, tissue-specific process, cooperatively regulated by several CKIs, and is critical for the lifelong survival of these sensory cells.
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Affiliation(s)
| | - Angelika Doetzlhofer
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, California 90057, and
| | | | | | - Marikki Laiho
- Molecular Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, 00014 Helsinki, Finland
| | - Martine F. Roussel
- Department of Tumor Biology and Genetics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Neil Segil
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, California 90057, and
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50
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Harding GW, Bohne BA, Lee SC, Salt AN. Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise. Hear Res 2007; 225:128-38. [PMID: 17300889 PMCID: PMC2593403 DOI: 10.1016/j.heares.2007.01.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 01/05/2007] [Accepted: 01/11/2007] [Indexed: 01/12/2023]
Abstract
Infrasound (i.e., <20 Hz for humans; <100 Hz for chinchillas) is not audible, but exposure to high-levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4 kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24h. For each animal, the tympanic membrane (TM) in one ear was perforated ( approximately 1 mm(2)) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4 kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10-21 dB DPOAE LS from 0.6 to 2 kHz. The infrasound exposure alone resulted in a 10-20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4 kHz OBN alone at 108 dB produced a 10-50 dB ABR TS for 0.5-12 kHz, a 10-60 dB DPOAE LS for 0.6-16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4 kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4 kHz OBN alone. Exposure to only the 4 kHz OBN at 86 dB produces a 10-40 dB ABR TS for 3-12 kHz and 10-30 dB DPOAE LS for 3-8 kHz but little or no OHC loss in the middle of the first turn. No differences were found in the functional and hair-cell losses from exposure to the 4 kHz OBN at 86 dB in the presence or absence of infrasound. We hypothesize that exposure to infrasound and an intense 4 kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound and a moderate 4 kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this moderate level exposure.
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Affiliation(s)
- Gary W Harding
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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