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Pisani A, Paciello F, Montuoro R, Rolesi R, Galli J, Fetoni AR. Antioxidant Therapy as an Effective Strategy against Noise-Induced Hearing Loss: From Experimental Models to Clinic. Life (Basel) 2023; 13:life13041035. [PMID: 37109564 PMCID: PMC10144536 DOI: 10.3390/life13041035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/05/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Cochlear redox unbalance is the main mechanism of damage involved in the pathogenesis of noise-induced-hearing loss. Indeed, the increased free radical production, in conjunction with a reduced efficacy of the endogenous antioxidant system, plays a key role in cochlear damage induced by noise exposure. For this reason, several studies focused on the possibility to use exogenous antioxidant to prevent or attenuate noise-induce injury. Thus, several antioxidant molecules, alone or in combination with other compounds, have been tested in both experimental and clinical settings. In our findings, we tested the protective effects of several antioxidant enzymes, spanning from organic compounds to natural compounds, such as nutraceuticals of polyphenols. In this review, we summarize and discuss the strengths and weaknesses of antioxidant supplementation focusing on polyphenols, Q-Ter, the soluble form of CoQ10, Vitamin E and N-acetil-cysteine, which showed great otoprotective effects in different animal models of noise induced hearing loss and which has been proposed in clinical trials.
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Affiliation(s)
- Anna Pisani
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Fabiola Paciello
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Raffaele Montuoro
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Rolando Rolesi
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Jacopo Galli
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Anna Rita Fetoni
- Department of Neuroscience, Reproductive Sciences and Dentistry-Audiology Section, University of Naples Federico II, 80131 Naples, Italy
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Krishnan Muthaiah VP, Kaliyappan K, Mahajan SD. Poly ADP-Ribose Polymerase-1 inhibition by 3-aminobenzamide recuperates HEI-OC1 auditory hair cells from blast overpressure-induced cell death. Front Cell Dev Biol 2023; 11:1047308. [PMID: 36949771 PMCID: PMC10025353 DOI: 10.3389/fcell.2023.1047308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 01/30/2023] [Indexed: 03/08/2023] Open
Abstract
Introduction: Poly ADP-Ribose Polymerase-1 (PARP1), a DNA repair enzyme is implicated as a key molecule in the pathogenesis of several neurodegenerative disorders. Traumatic insults inducing oxidative stress results in its over-activation causing inflammation and cell death (Parthanatos). As PARP1 inhibition is known to reduce oxidative stress, we hypothesized that PARP1 inhibition by a known inhibitor 3-aminobenzamide (3AB) might recuperate the damage in an in vitro model of blast injury using HEI-OC1 cells (mouse auditory hair cells). Methods: Here, we evaluated the protective effect of 3AB on HEI-OC1 cells following single and repetitive blast overpressures (BOPs). Results: We found that inhibition of PARP1 b 3AB inhibits the PARP1 enzyme and its action of a post-translational modification i.e. formation of Poly ADP-Ribose Polymers which leads to massive ATP depletion. PARP inhibition (3AB treatment) reduced the oxidative stress (4HNE, a marker of lipid peroxidation, and 8OHdG, a marker of oxidative DNA damage) in cells exposed to single/repetitive BOPS through up-regulation of Nrf2, a transcriptional regulator of antioxidant defense and the GCLC, a rate limiting enzyme in the synthesis of glutathione. Discussion: Overall, we found that PARP inhibition by 3AB helps to maintain the viability of BOP-exposed auditory hair cells by recuperating the ATP pool from both mitochondrial and glycolytic sources.
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Affiliation(s)
- Vijaya Prakash Krishnan Muthaiah
- Department of Rehabilitation Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- *Correspondence: Vijaya Prakash Krishnan Muthaiah,
| | - Kathiravan Kaliyappan
- Department of Rehabilitation Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Supriya D. Mahajan
- Department of Medicine, Division of Allergy, Immunology and Rheumatology, State University of New York at Buffalo, Clinical Translational Research Center, Buffalo, NY, United States
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The Protective Effects of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells in Noise-Induced Hearing Loss of Rats. Cells 2022; 11:cells11213524. [DOI: 10.3390/cells11213524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 10/24/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
A few prior animal studies have suggested the transplantation or protective effects of mesenchymal stem cells (MSCs) in noise-induced hearing loss. This study intended to evaluate the fates of administered MSCs in the inner ears and the otoprotective effects of MSCs in the noise-induced hearing loss of rats. Human embryonic stem cell-derived MSCs (ES-MSCs) were systematically administered via the tail vein in adult rats. Eight-week-old Sprague-Dawley rats were randomly allocated to the control (n = 8), ES-MSC (n = 4), noise (n = 8), and ES-MSC+noise (n = 10) groups. In ES-MSC and ES-MSC+noise rats, 5 × 105 ES-MSCs were injected via the tail vein. In noise and ES-MSC+noise rats, broadband noise with 115 dB SPL was exposed for 3 h daily for 5 days. The hearing levels were measured using auditory brainstem response (ABR) at 4, 8, 16, and 32 kHz. Cochlear histology was examined using H&E staining and cochlear whole mount immunofluorescence. The presence of human DNA was examined using Sry PCR, and the presence of human cytoplasmic protein was examined using STEM121 immunofluorescence staining. The protein expression levels of heat shock protein 70 (HSP70), apoptosis-inducing factor (AIF), poly (ADP-ribose) (PAR), PAR polymerase (PARP), caspase 3, and cleaved caspase 3 were estimated. The ES-MSC rats did not show changes in ABR thresholds following the administration of ES-MSCs. The ES-MSC+ noise rats demonstrated lower ABR thresholds at 4, 8, and 16 kHz than the noise rats. Cochlear spiral ganglial cells and outer hair cells were more preserved in the ES-MSC+ noise rats than in the noise rats. The Sry PCR bands were highly detected in lung tissue and less in cochlear tissue of ES-MSC+noise rats. Only a few STEM121-positivities were observed in the spiral ganglial cell area of ES-MSC and ES-MSC+noise rats. The protein levels of AIF, PAR, PARP, caspase 3, and cleaved caspase 3 were lower in the ES-MSC+noise rats than in the noise rats. The systemic injection of ES-MSCs preserved hearing levels and attenuated parthanatos and apoptosis in rats with noise-induced hearing loss. In addition, a tiny number of transplanted ES-MSCs were observed in the spiral ganglial areas.
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Protective and therapeutic effects of milrinone on acoustic trauma in rat cochlea. Eur Arch Otorhinolaryngol 2019; 276:1921-1931. [DOI: 10.1007/s00405-019-05417-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 03/31/2019] [Indexed: 10/27/2022]
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Morioka S, Sakaguchi H, Yamaguchi T, Ninoyu Y, Mohri H, Nakamura T, Hisa Y, Ogita K, Saito N, Ueyama T. Hearing vulnerability after noise exposure in a mouse model of reactive oxygen species overproduction. J Neurochem 2018; 146:459-473. [PMID: 29675997 DOI: 10.1111/jnc.14451] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/09/2018] [Accepted: 04/10/2018] [Indexed: 12/20/2022]
Abstract
Previous studies have convincingly argued that reactive oxygen species (ROS) contribute to the development of several major types of sensorineural hearing loss, such as noise-induced hearing loss (NIHL), drug-induced hearing loss, and age-related hearing loss. However, the underlying molecular mechanisms induced by ROS in these pathologies remain unclear. To resolve this issue, we established an in vivo model of ROS overproduction by generating a transgenic (TG) mouse line expressing the human NADPH oxidase 4 (NOX4, NOX4-TG mice), which is a constitutively active ROS-producing enzyme that does not require stimulation or an activator. Overproduction of ROS was detected at the cochlea of the inner ear in NOX4-TG mice, but they showed normal hearing function under baseline conditions. However, they demonstrated hearing function vulnerability, especially at high-frequency sounds, upon exposure to intense noise, which was accompanied by loss of cochlear outer hair cells (OHCs). The vulnerability to loss of hearing function and OHCs was rescued by treatment with the antioxidant Tempol. Additionally, we found increased protein levels of the heat-shock protein 47 (HSP47) in models using HEK293 cells, including H2 O2 treatment and cells with stable and transient expression of NOX4. Furthermore, the up-regulated levels of Hsp47 were observed in both the cochlea and heart of NOX4-TG mice. Thus, antioxidant therapy is a promising approach for the treatment of NIHL. Hsp47 may be an endogenous antioxidant factor, compensating for the chronic ROS overexposure in vivo, and counteracting ROS-related hearing loss.
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Affiliation(s)
- Shigefumi Morioka
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan.,Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hirofumi Sakaguchi
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Taro Yamaguchi
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Osaka, Japan
| | - Yuzuru Ninoyu
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
| | - Hiroaki Mohri
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
| | - Takashi Nakamura
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
| | - Yasuo Hisa
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Faculty of Health and Medical Sciences, Kyoto Gakuen University, Kyoto, Japan
| | - Kiyokazu Ogita
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Osaka, Japan
| | - Naoaki Saito
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
| | - Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
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Fitzakerley JL, Trachte GJ. Genetics of guanylyl cyclase pathways in the cochlea and their influence on hearing. Physiol Genomics 2018; 50:780-806. [PMID: 29958079 DOI: 10.1152/physiolgenomics.00056.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although hearing loss is the most common sensory deficit in Western societies, there are no successful pharmacological treatments for this disorder. Recent experiments have demonstrated that manipulation of intracellular cyclic guanosine monophosphate (cGMP) concentrations can have both beneficial and harmful effects on hearing. In this review, we will examine the role of cGMP as a key second messenger involved in many aspects of cochlear function and discuss the known functions of downstream effectors of cGMP in sound processing. The nitric oxide-stimulated soluble guanylyl cyclase system (sGC) and the two natriuretic peptide-stimulated particulate GCs (pGCs) will be more extensively covered because they have been studied most thoroughly. The cochlear GC systems are attractive targets for medical interventions that improve hearing while simultaneously representing an under investigated source of sensorineural hearing loss.
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Affiliation(s)
- Janet L Fitzakerley
- Department of Biomedical Sciences, University of Minnesota Medical School , Duluth, Minnesota
| | - George J Trachte
- Department of Biomedical Sciences, University of Minnesota Medical School , Duluth, Minnesota
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Youn CK, Kim J, Jo ER, Oh J, Do NY, Cho SI. Protective Effect of Tempol against Cisplatin-Induced Ototoxicity. Int J Mol Sci 2016; 17:ijms17111931. [PMID: 27869744 PMCID: PMC5133926 DOI: 10.3390/ijms17111931] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 11/01/2016] [Accepted: 11/15/2016] [Indexed: 01/22/2023] Open
Abstract
One of the major adverse effects of cisplatin chemotherapy is hearing loss. Cisplatin-induced ototoxicity hampers treatment because it often necessitates dose reduction, which decreases cisplatin efficacy. This study was performed to investigate the effect of Tempol on cisplatin-induced ototoxicity in an auditory cell line, House Ear Institute-Organ of Corti 1 (HEI-OC1). Cultured HEI-OC1 cells were exposed to 30 μM cisplatin for 24 h with or without a 2 h pre-treatment with Tempol. Cell viability was determined using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and apoptotic cells were identified using terminal deoxynucleotidyl transferase dUTP nick end labeling of nuclei (TUNEL) assay and flow cytometry. The effects of Tempol on cisplatin-induced cleaved poly(ADP-ribose) polymerase, cleaved caspase, and mitochondrial inducible nitric oxide synthase expression were evaluated using western blot analysis. Levels of intracellular reactive oxygen species (ROS) were measured to assess the effects of Tempol on cisplatin-induced ROS accumulation. Mitochondria were evaluated by confocal microscopy, and the mitochondrial membrane potential was measured to investigate whether Tempol protected against cisplatin-induced mitochondrial dysfunction. Cisplatin treatment decreased cell viability, and increased apoptotic features and markers, ROS accumulation, and mitochondrial dysfunction. Tempol pre-treatment before cisplatin exposure significantly inhibited all these cisplatin-induced effects. These results demonstrate that Tempol inhibits cisplatin-induced cytotoxicity in HEI-OC1, and could play a preventive role against cisplatin-induced ototoxicity.
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Affiliation(s)
- Cha Kyung Youn
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
- Division of Natural Medical Science, Chosun University School of Medicine, Gwangju 61452, Korea.
| | - Jun Kim
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
| | - Eu-Ri Jo
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
| | - Jeonghyun Oh
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
| | - Nam Yong Do
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
| | - Sung Il Cho
- Department of Otolaryngology-Head and Neck Surgery, Chosun University School of Medicine, Gwangju 61453, Korea.
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Nonoyama H, Tanigawa T, Shibata R, Tanaka H, Katahira N, Horibe Y, Takemura K, Murotani K, Ozeki N, Ueda H. Investigation of the ototoxicity of gadoteridol (ProHance) and gadodiamide (Omniscan) in mice. Acta Otolaryngol 2016; 136:1091-1096. [PMID: 27315460 DOI: 10.1080/00016489.2016.1193892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CONCLUSION In the mouse, when a tympanic perforation is present, gadoteridol does not seem to cause ototoxicity. Gadodiamide may cause mild ototoxicity other than toxicity to the outer hair cells of the cochlea. OBJECTIVES Endolymphatic hydrops have been visualized through intra-tympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, reports on the safety of GBCAs are limited. This study aimed to assess ototoxicity of gadoteridol and gadodiamide. METHOD In a prospective, randomized, controlled trial, myringotomies in the left ear were performed in 20 male C57 BL/6 mice. After testing the baseline auditory brainstem response (ABR) (range = 8-32 kHz), the test solution (gadoteridol, gadodiamide, saline, or cisplatin) was injected into the left ear. ABR testing was repeated 14 days after test solution application. In morphological experiments, images of post-mortem surface preparations were assessed for cochlear hair cell status. RESULTS At 14 days following gadoteridol application, there was no significant change in ABR thresholds at 8, 16, or 32 kHz. Gadodiamide application caused a significant change in the ABR threshold at 8 kHz. Apparent cochlear hair cell loss was not observed in the surface preparation after gadoteridol or gadodiamide application.
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Ogurlu M, Celebi Erdivanli O, Tumkaya L, Ozgur A, Ozergin Coskun Z, Terzi S, Demirci M, Dursun E. The therapeutic effect of thymoquinone on acoustic trauma-induced hearing loss in rats. Eur Arch Otorhinolaryngol 2016; 274:743-749. [PMID: 27766410 DOI: 10.1007/s00405-016-4319-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 09/22/2016] [Indexed: 12/17/2022]
Abstract
Thymoquinone has antioxidant properties. We hypothesized that thymoquinone may prevent or alleviate hearing loss induced by acoustic trauma. We aimed to study thymoquinone's effect on hearing function with distortion-product otoacoustic emissions and auditory brainstem response. Thirty adult Spraque Dawley rats were randomized into four groups following exposure to acoustic trauma for 4 h. Control group (n = 7) did not receive further treatment. Thymoquinone-20 (n = 8) and Thymoquinone-40 (n = 8) received 20 and 40 mg/kg of intraperitoneal thymoquinone, respectively. Corn-oil group (n = 7) received 1 ml of corn oil intraperitoneally. Hearing function of both ears was tested with distortion-product otoacoustic emission and auditory brainstem response before, and shortly after acoustic trauma, and 96 h following acoustic trauma. Post-trauma signal/noise ratios and wave V amplitude/latencies of all groups were significantly low compared with pre-trauma values, which indicate no preventive effect of thymoquinone. Rats in Thymoquinone-20 showed a significantly improved distortion-product otoacoustic emission and auditory brainstem response results at 4000 frequency and above in post-treatment tests (p < 0.05). Improvement in Thymoquinone-40 at the same frequencies was insignificantly inferior to Thymoquinone-20, yet superior to control and corn-oil groups (p < 0.05). We conclude that thymoquinone may not prevent acoustic trauma-induced hearing loss, however, at 20 mg/kg for 96 h, may repair the damage.
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Affiliation(s)
- Mahmut Ogurlu
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Ozlem Celebi Erdivanli
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey. .,İslampaşa mahallesi, Recep Tayyip Erdoğan Üniversitesi Tıp Fakültesi Eğitim ve Araştırma Hastanesi, Kulak Burun Boğaz Anabilim Dalı, 53100, Rize, Türkiye.
| | - Levent Tumkaya
- Department of Histology and Embryology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Abdulkadir Ozgur
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Zerrin Ozergin Coskun
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Suat Terzi
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Munir Demirci
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
| | - Engin Dursun
- Department of Otorhinolaryngology, Recep Tayyip Erdogan University Medical Faculty, Rize, Turkey
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Xiong M, Zhu Y, Lai H, Fu X, Deng W, Yang C, He Q, Zheng G. Radix astragali inhibits the down-regulation of connexin 26 in the stria vascularis of the guinea pig cochlea after acoustic trauma. Eur Arch Otorhinolaryngol 2014; 272:2153-60. [DOI: 10.1007/s00405-014-3093-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 05/06/2014] [Indexed: 12/26/2022]
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Barker M, Solinski HJ, Hashimoto H, Tagoe T, Pilati N, Hamann M. Acoustic overexposure increases the expression of VGLUT-2 mediated projections from the lateral vestibular nucleus to the dorsal cochlear nucleus. PLoS One 2012; 7:e35955. [PMID: 22570693 PMCID: PMC3343051 DOI: 10.1371/journal.pone.0035955] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 03/28/2012] [Indexed: 11/19/2022] Open
Abstract
The dorsal cochlear nucleus (DCN) is a first relay of the central auditory system as well as a site for integration of multimodal information. Vesicular glutamate transporters VGLUT-1 and VGLUT-2 selectively package glutamate into synaptic vesicles and are found to have different patterns of organization in the DCN. Whereas auditory nerve fibers predominantly co-label with VGLUT-1, somatosensory inputs predominantly co-label with VGLUT-2. Here, we used retrograde and anterograde transport of fluorescent conjugated dextran amine (DA) to demonstrate that the lateral vestibular nucleus (LVN) exhibits ipsilateral projections to both fusiform and deep layers of the rat DCN. Stimulating the LVN induced glutamatergic synaptic currents in fusiform cells and granule cell interneurones. We combined the dextran amine neuronal tracing method with immunohistochemistry and showed that labeled projections from the LVN are co-labeled with VGLUT-2 by contrast to VGLUT-1. Wistar rats were exposed to a loud single tone (15 kHz, 110 dB SPL) for 6 hours. Five days after acoustic overexposure, the level of expression of VGLUT-1 in the DCN was decreased whereas the level of expression of VGLUT-2 in the DCN was increased including terminals originating from the LVN. VGLUT-2 mediated projections from the LVN to the DCN are likely to play a role in the head position in response to sound. Amplification of VGLUT-2 expression after acoustic overexposure could be a compensatory mechanism from vestibular inputs in response to hearing loss and to a decrease of VGLUT-1 expression from auditory nerve fibers.
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Affiliation(s)
- Matthew Barker
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
| | - Hans Jürgen Solinski
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
| | - Haruka Hashimoto
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
| | - Thomas Tagoe
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
| | - Nadia Pilati
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
| | - Martine Hamann
- Department of Cell Physiology and Pharmacology, Leicester University, Leicester, United Kingdom
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Pilati N, Large C, Forsythe ID, Hamann M. Acoustic over-exposure triggers burst firing in dorsal cochlear nucleus fusiform cells. Hear Res 2012; 283:98-106. [PMID: 22085487 PMCID: PMC3315001 DOI: 10.1016/j.heares.2011.10.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/12/2011] [Accepted: 10/28/2011] [Indexed: 01/31/2023]
Abstract
Acoustic over-exposure (AOE) triggers deafness in animals and humans and provokes auditory nerve degeneration. Weeks after exposure there is an increase in the cellular excitability within the dorsal cochlear nucleus (DCN) and this is considered as a possible neural correlate of tinnitus. The origin of this DCN hyperactivity phenomenon is still unknown but it is associated with neurons lying within the fusiform cell layer. Here we investigated changes of excitability within identified fusiform cells following AOE. Wistar rats were exposed to a loud (110 dB SPL) single tone (14.8 kHz) for 4 h. Auditory brainstem response recordings performed 3-4 days after AOE showed that the hearing thresholds were significantly elevated by about 20-30 dB SPL for frequencies above 15 kHz. Control fusiform cells fired with a regular firing pattern as assessed by the coefficient of variation of the inter-spike interval distribution of 0.19 ± 0.11 (n = 5). Three to four days after AOE, 40% of fusiform cells exhibited irregular bursting discharge patterns (coefficient of variation of the inter-spike interval distribution of 1.8 ± 0.6, n = 5; p < 0.05). Additionally the maximal firing following step current injections was reduced in these cells (from 83 ± 11 Hz, n = 5 in unexposed condition to 43 ± 6 Hz, n = 5 after AOE) and this was accompanied by an increased firing gain (from 0.09 ± 0.01 Hz/pA, n = 5 in unexposed condition to 0.56 ± 0.25 Hz/pA, n = 5 after AOE). Current and voltage clamp recordings suggest that the presence of bursts in fusiform cells is related to a down regulation of high voltage activated potassium currents. In conclusion we showed that AOE triggers deafness at early stages and this is correlated with profound changes in the firing pattern and frequency of the DCN major output fusiform cells. The changes here described could represent the initial network imbalance prior to the emergence of tinnitus.
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Key Words
- abr, auditory brainstem response
- acsf, artificial cerebrospinal fluid
- ap, action potential
- aoe, acoustic over-exposure
- cnqx, 6-cyano-7-nitroquinoxaline-2,3-dione
- cv, coefficient of variation
- cw, cartwheel cells
- dcn, dorsal cochlear nucleus
- dl-ap5, dl-2-amino-5-phosphonopentanoic acid
- dnqx, 6,7-dinitroquinoxaline-2,3-dione
- fcs, fusiform cells
- ½ fmax, half maximal frequency
- hva, high voltage activated
- isi, inter-spike intervals
- fmax, maximal frequency
- n.s., non significant
- spl, sound pressure level
- vm, membrane potential
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Affiliation(s)
- Nadia Pilati
- Department of Cell Physiology and Pharmacology, Maurice Shock Medical Science Building, University of Leicester, University Road, Leicester LE1 9HN, UK
| | - Charles Large
- Neuroscience CEDD, GlaxoSmithKline S.p.A., Via Fleming 4, Verona 37135, Italy
| | - Ian D. Forsythe
- MRC Toxicology Unit, Hodgkin Building 1, University of Leicester, UK
| | - Martine Hamann
- Department of Cell Physiology and Pharmacology, Maurice Shock Medical Science Building, University of Leicester, University Road, Leicester LE1 9HN, UK
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Hoshino T, Tabuchi K, Nishimura B, Tanaka S, Nakayama M, Ishii T, Warabi E, Yanagawa T, Shimizu R, Yamamoto M, Hara A. Protective role of Nrf2 in age-related hearing loss and gentamicin ototoxicity. Biochem Biophys Res Commun 2011; 415:94-8. [PMID: 22020098 DOI: 10.1016/j.bbrc.2011.10.019] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 11/30/2022]
Abstract
Expression of antioxidant enzymes is regulated by transcription factor NF-E2-related factor (Nrf2) and induced by oxidative stress. Reactive oxygen species contribute to the formation of several types of cochlear injuries, including age-related hearing loss and gentamicin ototoxicity. In this study, we examined the roles of Nrf2 in age-related hearing loss and gentamicin ototoxicity by measuring auditory brainstem response thresholds in Nrf2-knockout mice. Although Nrf2-knockout mice maintained normal auditory thresholds at 3 months of age, their hearing ability was significantly more impaired than that of age-matched wild-type mice at 6 and 11 months of age. Additionally, the numbers of hair cells and spiral ganglion cells were remarkably reduced in Nrf2-knockout mice at 11 months of age. To examine the importance of Nrf2 in protecting against gentamicin-induced ototoxicity, 3-day-old mouse organ of Corti explants were cultured with gentamicin. Hair cell loss caused by gentamicin treatment was enhanced in the Nrf2-deficient tissues. Furthermore, the expressions of some Nrf2-target genes were activated by gentamicin treatment in wild-type mice but not in Nrf2-knockout mice. The present findings indicate that Nrf2 protects the inner ear against age-related hearing injuries and gentamicin ototoxicity by up-regulating antioxidant enzymes and detoxifying proteins.
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Affiliation(s)
- Tomofumi Hoshino
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
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15
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Tabuchi K, Hoshino T, Hirose Y, Hayashi K, Nishimura B, Nakayama M, Hara A. Age-related hearing loss and expression of antioxidant enzymes in BDF1 mice. Acta Otolaryngol 2011; 131:1020-4. [PMID: 21631178 DOI: 10.3109/00016489.2011.589406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION Our data suggest that the changes in expression of antioxidant enzymes may cause age-related hearing loss (AHL). OBJECTIVES AHL is an aging process of the inner ear, and oxidant stressors are considered to be one of the leading causes. We investigated the hearing level and expression profile of antioxidant enzymes in aged mice. METHODS Mice aged 3, 6, and 11 months were used. Hearing levels of the mice were examined using the auditory brainstem response (ABR). After measuring the ABR threshold, cochleae were dissected. RNA was isolated from the cochleae, and cDNA was synthesized using the retro-transcription enzyme. Expression of the antioxidant enzymes was measured by quantitative real-time PCR. RESULTS The ABR thresholds of the BDF1 mice were elevated by 6 months of age. The expression of superoxide dismutase 1 (SOD1) and heme oxygenase 1 (HO1) at 11 months of age significantly decreased compared with that of those at 6 months of age. In contrast, a decrease in the expression level was not observed regarding NAD(P)H-quinone oxidoreductase 1 (NQO1).
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Affiliation(s)
- Keiji Tabuchi
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Japan.
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Sahaboglu A, Tanimoto N, Kaur J, Sancho-Pelluz J, Huber G, Fahl E, Arango-Gonzalez B, Zrenner E, Ekström P, Löwenheim H, Seeliger M, Paquet-Durand F. PARP1 gene knock-out increases resistance to retinal degeneration without affecting retinal function. PLoS One 2010; 5:e15495. [PMID: 21124852 PMCID: PMC2990765 DOI: 10.1371/journal.pone.0015495] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 10/03/2010] [Indexed: 11/25/2022] Open
Abstract
Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases affecting photoreceptors and causing blindness in humans. Previously, excessive activation of enzymes belonging to the poly-ADP-ribose polymerase (PARP) group was shown to be involved in photoreceptor degeneration in the human homologous rd1 mouse model for RP. Since there are at least 16 different PARP isoforms, we investigated the exact relevance of the predominant isoform - PARP1 - for photoreceptor cell death using PARP1 knock-out (KO) mice. In vivo and ex vivo morphological analysis using optic coherence tomography (OCT) and conventional histology revealed no major alterations of retinal phenotype when compared to wild-type (wt). Likewise, retinal function as assessed by electroretinography (ERG) was normal in PARP1 KO animals. We then used retinal explant cultures derived from wt, rd1, and PARP1 KO animals to test their susceptibility to chemically induced photoreceptor degeneration. Since photoreceptor degeneration in the rd1 retina is triggered by a loss-of-function in phosphodiesterase-6 (PDE6), we used selective PDE6 inhibition to emulate the rd1 situation on non-rd1 genotypes. While wt retina subjected to PDE6 inhibition showed massive photoreceptor degeneration comparable to rd1 retina, in the PARP1 KO situation, cell death was robustly reduced. Together, these findings demonstrate that PARP1 activity is in principle dispensable for normal retinal function, but is of major importance for photoreceptor degeneration under pathological conditions. Moreover, our results suggest that PARP dependent cell death or PARthanatos may play a major role in retinal degeneration and highlight the possibility to use specific PARP inhibitors for the treatment of RP.
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Affiliation(s)
- Ayse Sahaboglu
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Naoyuki Tanimoto
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Jasvir Kaur
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Javier Sancho-Pelluz
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Gesine Huber
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Edda Fahl
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Blanca Arango-Gonzalez
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Eberhart Zrenner
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Per Ekström
- Department of Ophthalmology, Clinical Sciences Lund, University of Lund, Lund, Sweden
| | - Hubert Löwenheim
- Otolaryngology Department, University of Tübingen, Tübingen, Germany
| | - Mathias Seeliger
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - François Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
- * E-mail:
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Hoshino T, Tabuchi K, Hara A. Effects of NSAIDs on the Inner Ear: Possible Involvement in Cochlear Protection. Pharmaceuticals (Basel) 2010; 3:1286-1295. [PMID: 27713301 PMCID: PMC4033980 DOI: 10.3390/ph3051286] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 04/12/2010] [Accepted: 04/22/2010] [Indexed: 01/04/2023] Open
Abstract
Cyclooxygenase and lipoxygenase, two important enzymes involved in arachidonic acid metabolism, are major targets of non-steroidal anti-inflammatory drugs (NSAIDs). Recent investigations suggest that arachidonic cascades and their metabolites may be involved in maintaining inner ear functions. The excessive use of aspirin may cause tinnitus in humans and impairment of the outer hair cell functions in experimental animals. On the other hand, NSAIDs reportedly exhibit protective effects against various kinds of inner ear disorder. The present review summarizes the effects of NSAIDs on cochlear pathophysiology. NSAIDs are a useful ameliorative adjunct in the management of inner ear disorders.
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Affiliation(s)
- Tomofumi Hoshino
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
| | - Keiji Tabuchi
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
| | - Akira Hara
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
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18
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Tanaka S, Tabuchi K, Hoshino T, Murashita H, Tsuji S, Hara A. Protective effects of exogenous GM-1 ganglioside on acoustic injury of the mouse cochlea. Neurosci Lett 2010; 473:237-41. [DOI: 10.1016/j.neulet.2010.02.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/16/2010] [Accepted: 02/22/2010] [Indexed: 10/19/2022]
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19
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Nagashima R, Yamaguchi T, Tanaka H, Ogita K. Mechanism Underlying the Protective Effect of Tempol and Nω-Nitro-L-arginine Methyl Ester on Acoustic Injury: Possible Involvement of c-Jun N-Terminal Kinase Pathway and Connexin26 in the Cochlear Spiral Ligament. J Pharmacol Sci 2010; 114:50-62. [DOI: 10.1254/jphs.10113fp] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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20
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Tabuchi K, Oikawa K, Hoshino T, Nishimura B, Hayashi K, Yanagawa T, Warabi E, Ishii T, Tanaka S, Hara A. Cochlear protection from acoustic injury by inhibitors of p38 mitogen-activated protein kinase and sequestosome 1 stress protein. Neuroscience 2009; 166:665-70. [PMID: 20036720 DOI: 10.1016/j.neuroscience.2009.12.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 12/13/2009] [Accepted: 12/14/2009] [Indexed: 11/27/2022]
Abstract
This study evaluated the protective role of p38 mitogen-activated protein kinase (p38 MAPK) inhibitors and sequestosome 1 (Sqstm1/A170/p62), a stress-induced signal modulator, in acoustic injury of the cochlea in mice. Two weeks after the exposure of mice to acoustic stress, threshold shifts of the auditory brainstem response (ABR) from the pre-exposure level and hair cell loss were evaluated. The activation of p38 MAPK was observed in cochlea by immunostaining 4 h after acoustic stress. To examine the role of p38 MAPK in tissue injury, its inhibitors were i.p. injected into male wild-type C57BL mice before the acoustic overexposure. The inhibitors SB202190 and SB203580 but not the inactive analogue SB202474 dose-dependently decreased the auditory threshold shift and outer hair cell loss induced by acoustic overexposure, suggesting the involvement of p38 MAPK in ototoxicity. We found that acoustic overexposure induced the up-regulation of Sqstm1 mRNA expression in the cochlea of wild-type mice and that SQSTM1-deficient mice exhibited an enhanced ABR threshold shift and hair cell loss, suggesting a role of SQSTM1 in the protection of tissue from acoustic stress.
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Affiliation(s)
- K Tabuchi
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
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21
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22
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Uemaetomari I, Tabuchi K, Nakamagoe M, Tanaka S, Murashita H, Hara A. L-Type Voltage-Gated Calcium Channel is Involved in the Pathogenesis of Acoustic Injury in the Cochlea. TOHOKU J EXP MED 2009; 218:41-7. [DOI: 10.1620/tjem.218.41] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Isao Uemaetomari
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Keiji Tabuchi
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Mariko Nakamagoe
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Syuho Tanaka
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Hidekazu Murashita
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Akira Hara
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba
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Ohlemiller KK. Recent findings and emerging questions in cochlear noise injury. Hear Res 2008; 245:5-17. [PMID: 18790034 PMCID: PMC2610263 DOI: 10.1016/j.heares.2008.08.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 08/12/2008] [Accepted: 08/19/2008] [Indexed: 12/11/2022]
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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Hoshino T, Tabuchi K, Hirose Y, Uemaetomari I, Murashita H, Tobita T, Hara A. The non-steroidal anti-inflammatory drugs protect mouse cochlea against acoustic injury. TOHOKU J EXP MED 2008; 216:53-9. [PMID: 18719338 DOI: 10.1620/tjem.216.53] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Acoustic injury is a common cause of hearing loss for people in industrial societies. Cyclooxygenase (COX) and lipoxygenase (LOX) are two important enzymes involved in arachidonic acid metabolism. Two COX isozymes are characterized, COX-1 and COX-2, that differ in terms of regulatory mechanisms of expression. Although COX-1, COX-2, and LOX are expressed in cochlea, their roles played in cochlear acoustic injury have not fully been evaluated. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit either COX or LOX, or both. This study evaluated the effects of NSAIDs on the functional recovery of the cochlea after acoustic injury. Mice were exposed to a 4-kHz pure tone of 128 dB SPL (sound pressure level) for 4 hours and received one of the following drugs for two weeks after acoustic overexposure: indomethacin (COX-1 inhibitor), meloxicam, SC58125, and CAY10404 (COX-2 inhibitors), and nordihydroguaiaretic acid (LOX inhibitor). The hearing ability was evaluated using an auditory brainstem response (ABR) before and after overexposure. The ABR threshold shifts, defined as subtraction between ABR thresholds before and after overexposure, were compared among the control and the medication groups at one and two weeks after acoustic overexposure. Treatment of mice with either indomethacin or nordihydroguaiaretic acid decreased the ABR threshold shifts after overexposure, indicating that COX-1 and LOX inhibitors exhibited protective effects against acoustic injury. In contrast, COX-2 inhibitors, meloxicam, SC58125, and CAY10404, showed no noticeable effects on the ABR threshold shifts. These findings suggest that COX-1 and LOX are involved in the pathogenesis of acoustic injury in cochlea.
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Affiliation(s)
- Tomofumi Hoshino
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
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Shi X, Han W, Yamamoto H, Omelchenko I, Nuttall A. Nitric oxide and mitochondrial status in noise-induced hearing loss. Free Radic Res 2008; 41:1313-25. [PMID: 17963121 DOI: 10.1080/10715760701687117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The study investigated the distribution of nitric oxide (NO) within isolated outer hair cells (OHCs) from the cochlea, its relationship to mitochondria and its modulation of mitochondrial function. Using two fluorescent dyes--4,5-diamino-fluorescein diacetate (DAF-2DA), which detects NO, and tetramethyl rhodamine methyl ester (TMRM+), a mitochondrial membrane potential dye--it was found that a relatively greater amount of the DAF fluorescence in OHCs co-localized with mitochondria in comparison to DAF fluorescence in the cytosole. This study also observed reduced mitochondrial membrane potential of OHCs and increased DAF fluorescence following exposure of the cells to noise (120 dB SPL for 4 h) and to an exogenous NO donor, NOC-7 (>350 mm). Antibody label for nitrotyrosine was also increased, indicating NO-related formation of peroxynitrite in both mitochondria and the cytosol. The results suggest that NO may play an important physiological role in regulating OHC energy status and act as a potential agent in OHC pathology.
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Affiliation(s)
- Xiaorui Shi
- Oregon Hearing Research Center (NRC04), Portland, OR 97239-3098, USA
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26
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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] [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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Murashita H, Tabuchi K, Sakai S, Uemaetomari I, Tsuji S, Hara A. The effect of a GABAA agonist muscimol on acoustic injury of the mouse cochlea. Neurosci Lett 2007; 418:18-21. [PMID: 17353094 DOI: 10.1016/j.neulet.2007.02.060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 02/26/2007] [Accepted: 02/26/2007] [Indexed: 11/22/2022]
Abstract
Gamma-aminobutyric acid (GABA) is one of major inhibitory neurotransmitter in the central nervous system and constitutes the cochlear efferent system. Glutamate excitotoxicity is implicated in the pathogenesis of acoustic injury of the cochlea. The present work investigated whether GABA(A) agonist muscimol can alleviate acoustic injury. Mice were exposed to a 4 kHz pure tone of 128 dB SPL for 4h. Muscimol and/or bicuculline, a GABA(A) antagonist, were intraperitoneally administered immediately before the onset of acoustic overexposure. The threshold shifts of the auditory brainstem response (ABR) and cochlear morphology after acoustic overexposure were then evaluated. Muscimol significantly decreased the ABR threshold shift and inhibited swelling of the afferent dendrites induced by acoustic overexposure. In addition, bicuculline inhibited the effects of muscimol. These findings suggest that activation of GABA(A) receptors reduces acoustic injury of the cochlea.
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Affiliation(s)
- Hidekazu Murashita
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, Majors of Functional and Regulatory Medical Sciences, University of Tsukuba, Tsukuba, Japan
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28
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Hirose Y, Tabuchi K, Oikawa K, Murashita H, Sakai S, Hara A. The effects of the glucocorticoid receptor antagonist RU486 and phospholipase A2 inhibitor quinacrine on acoustic injury of the mouse cochlea. Neurosci Lett 2006; 413:63-7. [PMID: 17145133 DOI: 10.1016/j.neulet.2006.11.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 11/06/2006] [Accepted: 11/13/2006] [Indexed: 12/20/2022]
Abstract
Glucocorticoids are used clinically for the treatment of acoustic injury. However, the protective mechanism of glucocorticoid in acoustic injury has not been completely clarified. Also, the effects of phospholipase A2 (PLA2) on acoustic injury have not been examined to the best of our knowledge. The purpose of the present study was to examine the effects of methylprednisolone, a glucocorticoid receptor inhibitor (RU486) and a phospholipase A2 inhibitor (quinacrine) on cochlear injury induced by acoustic overexposure. Seventy-eight mice were exposed to a 4kHz pure tone at 128dB SPL for 4h. The auditory brainstem response (ABR) was used to examine the hearing thresholds. Cochlear morphology was examined to estimate the outer hair cell loss induced by acoustic overexposure. Methylprednisolone and quinacrine significantly alleviated the hearing threshold shift and hair cell loss induced by acoustic overexposure. RU486 antagonized the protective effect of methylprednisolone. The present findings suggest firstly that glucocorticoids exert protective effects against acoustic injury; secondly, that the protective effect of methylprednisolone was exerted by binding glucocorticoid receptors, and finally that activation of PLA2 may be involved in acoustic injury.
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Affiliation(s)
- Yuki Hirose
- Department of Otolaryngology, Graduate School of Comprehensive Human Sciences, Majors of Functional and Regulatory Medical Sciences, University of Tsukuba, Tsukuba, Japan
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