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Yeo XY, Kwon S, Rinai KR, Lee S, Jung S, Park R. A Consolidated Understanding of the Contribution of Redox Dysregulation in the Development of Hearing Impairment. Antioxidants (Basel) 2024; 13:598. [PMID: 38790703 PMCID: PMC11118506 DOI: 10.3390/antiox13050598] [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: 02/22/2024] [Revised: 04/26/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
The etiology of hearing impairment is multifactorial, with contributions from both genetic and environmental factors. Although genetic studies have yielded valuable insights into the development and function of the auditory system, the contribution of gene products and their interaction with alternate environmental factors for the maintenance and development of auditory function requires further elaboration. In this review, we provide an overview of the current knowledge on the role of redox dysregulation as the converging factor between genetic and environmental factor-dependent development of hearing loss, with a focus on understanding the interaction of oxidative stress with the physical components of the peripheral auditory system in auditory disfunction. The potential involvement of molecular factors linked to auditory function in driving redox imbalance is an important promoter of the development of hearing loss over time.
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Affiliation(s)
- Xin Yi Yeo
- Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore;
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Soohyun Kwon
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
- Department of BioNanotechnology, Gachon University, Seongnam 13120, Republic of Korea
| | - Kimberley R. Rinai
- Department of Life Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Sungsu Lee
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital and Medical School, Gwangju 61469, Republic of Korea;
| | - Sangyong Jung
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Raekil Park
- Department of Biomedical Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju 61005, Republic of Korea
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Edvardsson Rasmussen J, Lundström P, Eriksson PO, Rask-Andersen H, Liu W, Laurell G. The Acute Effects of Furosemide on Na-K-Cl Cotransporter-1, Fetuin-A and Pigment Epithelium-Derived Factor in the Guinea Pig Cochlea. Front Mol Neurosci 2022; 15:842132. [PMID: 35392272 PMCID: PMC8981210 DOI: 10.3389/fnmol.2022.842132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/22/2022] [Indexed: 11/28/2022] Open
Abstract
Background Furosemide is a loop diuretic used to treat edema; however, it also targets the Na-K-Cl cotransporter-1 (NKCC1) in the inner ear. In very high doses, furosemide abolishes the endocochlear potential (EP). The aim of the study was to gain a deeper understanding of the temporal course of the acute effects of furosemide in the inner ear, including the protein localization of Fetuin-A and PEDF in guinea pig cochleae. Material and Method Adult guinea pigs were given an intravenous injection of furosemide in a dose of 100 mg per kg of body weight. The cochleae were studied using immunohistochemistry in controls and at four intervals: 3 min, 30 min, 60 min and 120 min. Also, cochleae of untreated guinea pigs were tested for Fetuin-A and PEDF mRNA using RNAscope® technology. Results At 3 min, NKCC1 staining was abolished in the type II fibrocytes in the spiral ligament, followed by a recovery period of up to 120 min. In the stria vascularis, the lowest staining intensity of NKCC1 presented after 30 min. The spiral ganglion showed a stable staining intensity for the full 120 min. Fetuin-A protein and mRNA were detected in the spiral ganglion type I neurons, inner and outer hair cells, pillar cells, Deiters cells and the stria vascularis. Furosemide induced an increased staining intensity of Fetuin-A at 120 min. PEDF protein and mRNA were found in the spiral ganglia type I neurons, the stria vascularis, and in type I and type II fibrocytes of the spiral ligament. PEDF protein staining intensity was high in the pillar cells in the organ of Corti. Furosemide induced an increased staining intensity of PEDF in type I neurons and pillar cells after 120 min. Conclusion The results indicate rapid furosemide-induced changes of NKCC1 in the type II fibrocytes. This could be part of the mechanism that causes reduction of the EP within minutes after high dose furosemide injection. Fetuin-A and PEDF are present in many cells of the cochlea and probably increase after furosemide exposure, possibly as an otoprotective response.
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Lin X, Luo J, Tan J, Yang L, Wang M, Li P. Experimental animal models of drug-induced sensorineural hearing loss: a narrative review. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1393. [PMID: 34733945 PMCID: PMC8506545 DOI: 10.21037/atm-21-2508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 08/16/2021] [Indexed: 01/19/2023]
Abstract
Objective This narrative review describes experimental animal models of sensorineural hearing loss (SNHL) caused by ototoxic agents. Background SNHL primarily results from damage to the sensory organ within the inner ear or the vestibulocochlear nerve (cranial nerve VIII). The main etiology of SNHL includes genetic diseases, presbycusis, ototoxic agents, infection, and noise exposure. Animal models with functional and anatomic damage to the sensory organ within the inner ear or the vestibulocochlear nerve mimicking the damage seen in humans are employed to explore the mechanism and potential treatment of SNHL. These animal models of SNHL are commonly established using ototoxic agents. Methods A literature search of PubMed, Embase, and Web of Science was performed for research articles on hearing loss and ototoxic agents in animal models of hearing loss. Conclusions Common ototoxic medications such as aminoglycoside antibiotics (AABs) and platinum antitumor drugs are extensively used to induce SNHL in experimental animals. The effect of ototoxic agents in vivo is influenced by the chemical mechanisms of the ototoxic agents, the species of animal, routes of administration of the ototoxic agents, and the dosage of ototoxic agents. Animal models of drug-induced SNHL contribute to understanding the hearing mechanism and reveal the function of different parts of the auditory system in humans.
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Affiliation(s)
- Xuexin Lin
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jia Luo
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jingqian Tan
- Department of Otolaryngology Head and Neck Surgery, The Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Luoying Yang
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Mitian Wang
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University Yuedong Hospital, Meizhou, China
| | - Peng Li
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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Li W, Li D, Chen N, Liu P, Han S, Wang L, Gong S, Huang W, Ding D. Recording of electrocochleography from the facial nerve canal in mice. J Neurosci Methods 2021; 360:109256. [PMID: 34126140 DOI: 10.1016/j.jneumeth.2021.109256] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/03/2021] [Accepted: 06/09/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND The ever-expanding arsenal of genetically modified mice has created experimental models for studying various mechanisms of deafness. Electrocochleography (ECochG) is a recording technique of cochlear potentials evoked by sound stimulation, which was widely used to evaluate the cochlear hearing function. However, there is currently a lack of information on long-term recording technology of ECochG in mice. NEW METHOD We describe in detail the surgical procedure of implanting electrode into the facial nerve canal in C57BL/6J mice for ECochG recording. The results of ECochG recorded by electrode in the facial nerve canal were compared with ECochG guided by electrode on the round window niche. RESULTS The surgical method of inserting the electrode into the facial nerve canal is relatively simple and can be completed within 15 min. The electrode inserted into the elongated facial nerve canal is stable and close to the auditory nerve trunk, so it is conducive to long-term auditory function monitoring. Hence, the ECochG guided by the electrode from the facial nerve canal can maintain a stable response for more than two weeks. In contrast, the ECochG guided by the electrode in the round window niche can only be maintained for a maximum of 20 min. COMPARISON WITH EXISTING METHODS In mice, existing recording techniques of ECochG from round window niche is limited by conductive hearing loss due to middle ear effusion or surgical damage. CONCLUSIONS ECochG recording from the facial nerve canal is suitable for long-term recording in mice. This electrode approach provides a repeatable and reliable measurement of ECochG.
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Affiliation(s)
- Wenjuan Li
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China; Department of Otolaryngology, Children's Hospital of Shanxi, Women health of Shanxi, Taiyuan, China
| | - Dong Li
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Nina Chen
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Pan Liu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Shuguang Han
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Line Wang
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China.
| | - Shusheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China.
| | | | - Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, New York, United States of America
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Ding D, Zhang J, Li W, Li D, Yu J, Wu X, Qi W, Liu F, Jiang H, Shi H, Sun H, Li P, Huang W, Salvi R. Can auditory brain stem response accurately reflect the cochlear function? J Neurophysiol 2020; 124:1667-1675. [PMID: 33026904 DOI: 10.1152/jn.00233.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Auditory brain stem response (ABR) and compound action potential (CAP) recordings have been used in animal research to determine hearing sensitivity. Because of the relative ease of testing, the ABR test has been more commonly used in assessing cochlear lesions than the CAP test. The purpose of this experiment is to examine the difference between these two methods in monitoring the dynamic changes in auditory function after cochlear damage and in detecting asymmetric hearing loss due to unilateral cochlear damage. ABR and CAP were measured in two models of cochlear damage: acoustic trauma induced by exposure to a narrowband noise centered at 4 kHz (2,800-5,600 Hz) at 105 dB sound pressure level for 5 h in chinchillas and unilateral cochlear damage induced by surgical destruction of one cochlea in guinea pigs. Cochlear hair cells were quantified after completing the evoked potential testing. In the noise-damaged model, we found different recovery patterns between ABR and CAP. At 1 day after noise exposure, the ABR and CAP assessment revealed a similar level of threshold shifts. However, at 30 days after noise exposure, ABR thresholds displayed an average of 20-dB recovery, whereas CAP thresholds showed no recovery. Notably, the CAP threshold signifies the actual condition of sensory cell pathogenesis in the cochlea because sensory cell death is known to be irreversible in mammals. After unilateral cochlear damage, we found that both CAP and ABR were affected by cross-hearing when testing the damaged ear with the testing stimuli delivered directly into the canal of the damaged ear. When cross-hearing occurred, ABR testing was not able to reveal the presence of cross-hearing because the ABR waveform generated by cross-stimulation was indistinguishable from that generated by the test ear (damaged ear), should the test ear be intact. However, CAP testing can provide a warning sign, since the typical CAP waveform became an ABR-like waveform when cross-hearing occurred. Our study demonstrates two advantages of the CAP test over the ABR test in assessing cochlear lesions: contributing evidence for the occurrence of cross-hearing when subjects have asymmetric hearing loss and providing a better assessment of the progression of cochlear pathogenesis.NEW & NOTEWORTHY Auditory brain stem response (ABR) is more commonly used to evaluate cochlear lesions than cochlear compound action potential (CAP). In a noise-induced cochlear damage model, we found that the reduced CAP and enhanced ABR caused the threshold difference. In a unilateral cochlear destruction model, a shadow curve of the ABR from the contralateral healthy ear masked the hearing loss in the destroyed ear.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York.,The Third People's Hospital of Chengdu, Chengdu, China.,Shanghai Six People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Jianhui Zhang
- The Third People's Hospital of Chengdu, Chengdu, China
| | - Wenjuan Li
- Department of Otolaryngology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Dong Li
- Department of Otolaryngology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jintao Yu
- Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuewen Wu
- Xiangya Hospital, Central South University, Changsha, China
| | - Weidong Qi
- Huashan Hospital, Fudan University, Shanghai, China
| | - Fang Liu
- Beijing Hospital and National Center of Gerontology, Department of Otolaryngology, Beijing, China
| | - Haiyan Jiang
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York
| | - Haibo Shi
- Shanghai Six People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Hong Sun
- Xiangya Hospital, Central South University, Changsha, China
| | - Peng Li
- The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | | | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York
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Chen J, Liu Z, Yan H, Xing W, Mi W, Wang R, Li W, Chen F, Qiu J, Zha D. miR-182 prevented ototoxic deafness induced by co-administration of kanamycin and furosemide in rats. Neurosci Lett 2020; 723:134861. [PMID: 32105765 DOI: 10.1016/j.neulet.2020.134861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/19/2020] [Accepted: 02/22/2020] [Indexed: 12/12/2022]
Abstract
Ototoxic drugs may induce auditory sensory hair cell loss and permanent deafness; however, there is still no effective treatments or prevention strategies for this side effect. A recent study found that microRNA182 (miR-182) protected cochlear hair cells from ototoxic drug-induced apoptosis in vitro. However, it remains unclear whether miR-182 can protect drug-induced deafness in vivo. In this study, we overexpressed cochlear miR-182 in Sprague-Dawley rats by trans-round window niche delivery of miR-182 mimics. The rats subsequently received intraperitoneal injections of kanamycin and furosemide to induce acute cochlear outer hair cell death and permanent deafness. Auditory brainstem response tests showed that miR-182 attenuated permanent threshold shifts. Consistent with this result, miR-182 reduced the loss of outer hair cells and missing stereocilia. miR-182 treatment also increased the level of phosphoinositide-3 kinase regulatory subunit p85α in the outer hair cells after co-administration of kanamycin and furosemide. Our findings suggest that miR-182 has powerful protective potential against ototoxic drug-induced acute auditory sensory hair cell loss and permanent deafness.
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Affiliation(s)
- Jun Chen
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Zhenzhen Liu
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Hui Yan
- Department of Otolaryngology, the Bingtuan Hospital, the Second Affiliated Hospital, School of Medicine, Shihezi University, Xinjiang 830002, China
| | - Wei Xing
- Department of Otolaryngology, Sanitarial District, Lintong Sanatorium of Lanzhou Military Region, Xi'an, 710600, China
| | - Wenjuan Mi
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Renfeng Wang
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Wei Li
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Fuquan Chen
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China
| | - Jianhua Qiu
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China.
| | - Dingjun Zha
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an710032, China.
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Dkhar B, Bhatia A, Saikia PP, Pyngrope H. Improved postauricular surgical approach to the round window of rats. J Neurosci Methods 2020; 330:108481. [PMID: 31669291 DOI: 10.1016/j.jneumeth.2019.108481] [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: 12/21/2018] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Research using rat as an in-vivo model has played an important role in otological research. The rat ear anatomy has been described; however, detailed surgical procedures to access the temporal bone are limited. The authors present a technique to approach the inner ear of rat that was standardized by cadaveric dissections and later replicated in living animals. METHODS Adult Wistar albino rats were dissected via the post-auricular approach. The emphasis was on early identification of the facial nerve that formed a reliable landmark for the tympanic bulla, which in turn houses the round window and stapedial artery. The point of identification of facial nerve was postero-inferior to the external auditory meatus. The procedure was then repeated in living animals. RESULTS Seventeen cadaveric rats were dissected. Initially, the investigators attempted to identify the facial nerve at its crossing over the external auditory meatus. However, that method was found to be unsatisfactory. The facial nerve was then attempted to be identified in its course postero-inferior to the external auditory meatus. The technique improved drastically, and the facial nerve was identified promptly and reliably. The procedure was then repeated in seven living rats under general anaesthesia. The major issues encountered were bleeding from the stapedial artery, hematoma of the pinna in one rat. CONCLUSION This study suggests that the post-auricular approach is a feasible and less time consuming route for round window drug delivery experiments in Wistar albino rats. Recognition of anatomical landmarks, particularly the facial nerve is the key to surgery.
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Affiliation(s)
- Barilin Dkhar
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
| | - Abhijeet Bhatia
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India.
| | - Pranjal Pratim Saikia
- Department of Pharmacology, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
| | - Haphidasara Pyngrope
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
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Abstract
Tinnitus is a common symptom for which there is in most cases no causal therapy. The search for an improvement of tinnitus through pharmacological interventions has a long tradition. The observation that tinnitus can be transiently suppressed by the use of lidocaine has shown that the symptom is susceptible to pharmacotherapy. So far, however, no medication has been found for either acute or chronic subjective tinnitus that reliably leads to a long-term reduction or even complete disappearance of the symptom for the majority of tinnitus sufferers. Nevertheless, in everyday clinical life, drugs are frequently used, usually off-label, to relieve tinnitus or tinnitus-associated symptoms (e.g. sleep disturbance, depression, anxiety disorder or hearing loss). This chapter shows the different approaches to acute and chronic subjective tinnitus by means of pharmacotherapeutic interventions. Furthermore, this review reports on the scientific studies carried out in this area in recent years and explains the difficulties in finding a suitable medication for most forms of tinnitus. In addition, it reports on the pharmacotherapeutic options for objective tinnitus and describes the development of tinnitus as a side effect of certain drugs. Finally, possible target structures are mentioned, which should possibly be addressed in pharmacological studies in the near future.
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Affiliation(s)
- Tobias Kleinjung
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Berthold Langguth
- Department of Psychiatry and Psychotherapy, Interdisciplinary Tinnitus Center, University of Regensburg, Regensburg, Germany
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Guo J, Chai R, Li H, Sun S. Protection of Hair Cells from Ototoxic Drug-Induced Hearing Loss. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1130:17-36. [PMID: 30915699 DOI: 10.1007/978-981-13-6123-4_2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Hair cells are specialized sensory epithelia cells that receive mechanical sound waves and convert them into neural signals for hearing, and these cells can be killed or damaged by ototoxic drugs, including many aminoglycoside antibiotics, platinum-based anticancer agents, and loop diuretics, leading to drug-induced hearing loss. Studies of therapeutic approaches to drug-induced hearing loss have been hampered by the limited understanding of the biological mechanisms that protect and regenerate hair cells. This review briefly discusses some of the most common ototoxic drugs and describes recent research concerning the mechanisms of ototoxic drug-induced hearing loss. It also highlights current developments in potential therapies and explores current clinical treatments for patients with hearing impairments.
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Affiliation(s)
- Jin Guo
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department, Shanghai Engineering Research Centre of Cochlear Implant, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Renjie Chai
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department, Shanghai Engineering Research Centre of Cochlear Implant, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.,MOE Key Laboratory for Developmental Genes and Human Disease, Institute of Life Sciences, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
| | - Huawei Li
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department, Shanghai Engineering Research Centre of Cochlear Implant, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Shan Sun
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department, Shanghai Engineering Research Centre of Cochlear Implant, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
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Lee C, Jones TA. Acute blockade of inner ear marginal and dark cell K + secretion: Effects on gravity receptor function. Hear Res 2018; 361:152-156. [PMID: 29459166 DOI: 10.1016/j.heares.2018.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 12/13/2017] [Accepted: 02/09/2018] [Indexed: 11/18/2022]
Abstract
Specific pharmacological blockade of KCNQ (Kv7) channels with XE991 rapidly (within 20 min) and profoundly alters inner ear gravity receptor responses to head motion (Lee et al., 2017). We hypothesized that these effects were attributable to the suppression of K+ secretion following blockade of KCNQ1-KCNE1 channels in vestibular dark cells and marginal cells. To test this hypothesis, K+ secretion was independently inhibited by blocking the Na+-K+-2Cl- cotransporter (NKCC1, Slc12a2) rather than KCNQ1-KCNE1 channels. Acute blockade of NKCC1 with ethacrynic acid (40 mg/kg) eliminated auditory responses (ABRs) within approximately 70 min of injection, but had no effect on vestibular gravity receptor function (VsEPs) over a period of 2 h in the same animals. These findings show that, vestibular gravity receptors are highly resistant to acute disruption of endolymph secretion unlike the auditory system. Based on this we argue that acute suppression of K+ secretion alone does not likely account for the rapid profound effects of XE991 on gravity receptors. Instead the effects of XE991 likely require additional action at KCNQ channels located within the sensory epithelium itself.
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Affiliation(s)
- Choongheon Lee
- University of Nebraska-Lincoln, Department of Special Education and Communication Disorders, Lincoln, NE 68583-0738, USA.
| | - Timothy A Jones
- University of Nebraska-Lincoln, Department of Special Education and Communication Disorders, Lincoln, NE 68583-0738, USA.
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Ototoxic effects and mechanisms of loop diuretics. J Otol 2016; 11:145-156. [PMID: 29937824 PMCID: PMC6002634 DOI: 10.1016/j.joto.2016.10.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 12/22/2022] Open
Abstract
Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide only induces temporary hearing loss, but rarely permanent deafness unless applied in severe acute or chronic renal failure or with other ototoxic drugs. Loop diuretic induce unique pathological changes in the cochlea such as formation of edematous spaces in the epithelium of the stria vascularis, which leads to rapid decrease of the endolymphatic potential and eventual loss of the cochlear microphonic potential, summating potential, and compound action potential. Loop diuretics interfere with strial adenylate cyclase and Na+/K+-ATPase and inhibit the Na-K-2Cl cotransporter in the stria vascularis, however recent reports indicate that one of the earliest effects in vivo is to abolish blood flow in the vessels supplying the lateral wall. Since ethacrynic acid does not damage the stria vascularis in vitro, the changes in Na+/K+-ATPase and Na-K-2Cl seen in vivo may be secondary effects results from strial ischemia and anoxia. Recent observations showing that renin is present in pericytes surrounding stria arterioles suggest that diuretics may induce local vasoconstriction by renin secretion and angiotensin formation. The tight junctions in the blood-cochlea barrier prevent toxic molecules and pathogens from entering cochlea, but when diuretics induce a transient ischemia, the barrier is temporarily disrupted allowing the entry of toxic chemicals or pathogens.
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Walther LE, Hülse R, Lauer K, Wenzel A. [Current aspects of ototoxicity. Ototoxic substances and their effects]. HNO 2015; 63:315-24; quiz 325-6. [PMID: 25616875 DOI: 10.1007/s00106-014-2966-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Ototoxicity describes reversible or irreversible disorders of inner ear functions due to the influence of chemical, biological, or physical substances. Ototoxicity should be kept in mind during differential diagnosis of hearing loss, tinnitus, dizziness, and vertigo. In clinical practice, drug-induced ototoxic effects play a major role. The otorhinolaryngologist should also be involved in interdisciplinary cooperation, e.g., during treatment with antineoplastic chemotherapeutic agents with potential ototoxic side effects. In clinical practice, multimedication and interactions between different agents can complicate precise correlation in individual cases. Recent studies also show that noncellular components, such as otoconia, are extremely sensitive to chemical attacks.
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Affiliation(s)
- L E Walther
- HNO-Gemeinschaftspraxis, Main-Taunus-Zentrum, 65843, Sulzbach (Taunus), Deutschland,
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Establishment of a model of cochlear lesions in rats to study potential gene therapy for sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2015; 79:2147-54. [PMID: 26574172 DOI: 10.1016/j.ijporl.2015.09.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 09/23/2015] [Accepted: 09/30/2015] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Sensorineural hearing loss seriously influences a patient's daily life, and no effective treatments exist to date. Gene therapy is a potential treatment for regenerating hair cells to restore hearing. METHODS In this study, we established a cochlear lesions model to study hair cell regeneration by co-administration of kanamycin and furosemide. After the injections, we assessed the survival of outer hair cells (OHC), inner hair cells (IHC), supporting cells (SC), spiral ganglion neurons (SGN) and peripheral axons. Moreover, we used two viral vectors to detect the transgene distribution. RESULTS Our results showed at 12h post-treatment, numerous OHC were missing in the basal turn. At 24h post-treatment, all OHCs in basal half of the cochlea were lost, and by 48h, OHC loss had spread to the apical coil. Four days after the injections, all OHCs were absent. At 1mo post-treatment, the organ of Corti had collapsed. In contrast, most of the SC remained 4d after the injections. The loss of SGN and peripheral axons was consistent with this time course post-treatment. The results of transgene distribution suggested the correlative gene can be transferred into the organ of Corti using adenoviruses (AdV) vectors and lentiviruses (LV) vectors in our cochlear lesion model. COMPARISON WITH EXISTING METHOD(S) We assessed the details of HC death at more time point and chosen the time point for gene transfer in this model. CONCLUSIONS We conclude that this cochlear lesion model would be suitable for the study of hair cell regeneration.
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Jang JH, Lee HS, Oh SH, Park MH. Efficacy of the cat deafening method: Co-administration of ethacrynic acid and kanamycin. Acta Otolaryngol 2015; 136:289-92. [PMID: 26605909 DOI: 10.3109/00016489.2015.1110751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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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Baizer JS, Wong KM, Manohar S, Hayes SH, Ding D, Dingman R, Salvi RJ. Effects of acoustic trauma on the auditory system of the rat: The role of microglia. Neuroscience 2015; 303:299-311. [PMID: 26162240 DOI: 10.1016/j.neuroscience.2015.07.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 05/27/2015] [Accepted: 07/01/2015] [Indexed: 12/29/2022]
Abstract
Exposure to loud, prolonged sounds (acoustic trauma, AT) leads to the death of both inner and outer hair cells (IHCs and OHCs), death of neurons of the spiral ganglion and degeneration of the auditory nerve. The auditory nerve (8cn) projects to the three subdivisions of the cochlear nuclei (CN), the dorsal cochlear nucleus (DC) and the anterior (VCA) and posterior (VCP) subdivisions of the ventral cochlear nucleus (VCN). There is both anatomical and physiological evidence for plastic reorganization in the denervated CN after AT. Anatomical findings show axonal sprouting and synaptogenesis; physiologically there is an increase in spontaneous activity suggesting reorganization of circuitry. The mechanisms underlying this plasticity are not understood. Recent data suggest that activated microglia may have a role in facilitating plastic reorganization in addition to removing trauma-induced debris. In order to investigate the roles of activated microglia in the CN subsequent to AT we exposed animals to bilateral noise sufficient to cause massive hair cell death. We studied four groups of animals at different survival times: 30 days, 60 days, 6 months and 9 months. We used silver staining to examine the time course and pattern of auditory nerve degeneration, and immunohistochemistry to label activated microglia in the denervated CN. We found both degenerating auditory nerve fibers and activated microglia in the CN at 30 and 60 days and 6 months after AT. There was close geographic overlap between the degenerating fibers and activated microglia, consistent with a scavenger role for activated microglia. At the longest survival time, there were still silver-stained fibers but very little staining of activated microglia in overlapping regions. There were, however, activated microglia in the surrounding brainstem and cerebellar white matter.
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Affiliation(s)
- J S Baizer
- Department of Physiology & Biophysics, University at Buffalo, United States.
| | - K M Wong
- Department of Physiology & Biophysics, University at Buffalo, United States
| | - S Manohar
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, United States
| | - S H Hayes
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, United States
| | - D Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, United States
| | - R Dingman
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, United States
| | - R J Salvi
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, United States
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Li P, Ding D, Gao K, Salvi R. Standardized surgical approaches to ear surgery in rats. J Otol 2015; 10:72-77. [PMID: 29937785 PMCID: PMC6002556 DOI: 10.1016/j.joto.2015.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 03/15/2015] [Accepted: 03/30/2015] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVE To describe several approaches of ear surgeries for experimental studies in rats. METHODS Anesthetized rats were prepared for demonstration of various ear surgery approaches designed to optimize experimental outcomes in studies with specific goals and exposure requirements. The surgical approaches included the posterior tympanum, superior tympanum, inferior tympanum and occipital approaches. RESULTS The middle ear cavity and inner ear were successfully exposed from different angles via the mentioned surgical approaches. For example, electrode placement for recording of cochlear bioelectric responses was easily achieved through the posterior tympanum or inferior tympanum approach. Alternatively, drug delivery or gene transfection via round window membrane was most easily accomplished using the posterior tympanum approach. Cochlear perfusion of protective or ototoxic drugs was best performed using the inferior tympanum approach. Ossicular chain interruption to induce a prolonged conductive hearing loss was readily achieved using a superior tympanum approach. Lastly, surgical destruction of the endolymphatic sac to induce experimental endolymphatic hydrops was readily performed via an occipital surgical approach. CONCLUSION These standardized surgical approaches can be applied in scientific studies of the ear with different purposes covering electrophysiology, conductive hearing loss, intra-cochlear drug perfusion and experimental studies relevant to Meniere's disease.
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Affiliation(s)
- Peng Li
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510630, China
- Center for Hearing and Deafness, University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Dalian Ding
- Center for Hearing and Deafness, University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Hunan 410018, China
| | - Kelei Gao
- Center for Hearing and Deafness, University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Hunan 410018, China
| | - Richard Salvi
- Center for Hearing and Deafness, University of New York at Buffalo, Buffalo, NY 14214, USA
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Hunan 410018, China
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Pattern of hair cell loss and delayed peripheral neuron degeneration in inner ear by a high-dose intratympanic gentamicin. J Otol 2014. [DOI: 10.1016/j.joto.2014.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Hirose K, Li SZ, Ohlemiller KK, Ransohoff RM. Systemic lipopolysaccharide induces cochlear inflammation and exacerbates the synergistic ototoxicity of kanamycin and furosemide. J Assoc Res Otolaryngol 2014; 15:555-70. [PMID: 24845404 DOI: 10.1007/s10162-014-0458-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 04/21/2014] [Indexed: 12/20/2022] Open
Abstract
Aminoglycoside antibiotics are highly effective agents against gram-negative bacterial infections, but they cause adverse effects on hearing and balance dysfunction as a result of toxicity to hair cells of the cochlea and vestibular organs. While ototoxicity has been comprehensively studied, the contributions of the immune system, which controls the host response to infection, have not been studied in antibiotic ototoxicity. Recently, it has been shown that an inflammatory response is induced by hair cell injury. In this study, we found that lipopolysaccharide (LPS), an important component of bacterial endotoxin, when given in combination with kanamycin and furosemide, augmented the inflammatory response to hair cell injury and exacerbated hearing loss and hair cell injury. LPS injected into the peritoneum of experimental mice induced a brisk cochlear inflammatory response with recruitment of mononuclear phagocytes into the spiral ligament, even in the absence of ototoxic agents. While LPS alone did not affect hearing, animals that received LPS prior to ototoxic agents had worse hearing loss compared to those that did not receive LPS pretreatment. The poorer hearing outcome in LPS-treated mice did not correlate to changes in endocochlear potential. However, LPS-treated mice demonstrated an increased number of CCR2(+) inflammatory monocytes in the inner ear when compared with mice treated with ototoxic agents alone. We conclude that LPS and its associated inflammatory response are harmful to the inner ear when coupled with ototoxic medications and that the immune system may contribute to the final hearing outcome in subjects treated with ototoxic agents.
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Affiliation(s)
- Keiko Hirose
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110, USA,
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Abstract
HYPOTHESIS How to induce most efficiently severe sensorineural hearing loss in mice using a single coadministration of an aminoglycoside antibiotic and a loop diuretic? BACKGROUND The coadministration of aminoglycosides and a loop diuretic has been widely used to induce hair cell and spiral ganglion cell loss in guinea pigs. However, the development of new treatment strategies against sensorineural hearing loss, such as tissue engineering techniques, requires the use of mouse models. Previous attempts to induce hearing loss in mice have rendered inconsistent results because of resistance to aminoglycoside-induced ototoxicity. Especially inner hair cells seem to be resistant to aminoglycoside-induced ototoxicity. METHODS In the present study, we aim to optimize hearing loss in mice, using a single high-dose kanamycin (700 and 1,000 mg/kg) injection followed by a furosemide (100 mg/kg) administration. Although previous studies used intraperitoneal furosemide injections 30 minutes after kanamycin administration, we used intravenous furosemide injections administered within 5 minutes after kanamycin treatment. RESULTS Auditory brain stem responses illustrated severe threshold shifts, and histologic analysis showed marked outer hair cell destruction as well as spiral ganglion cell loss. The present protocol results in more severe inner hair cell loss when compared with the results of previous researches. CONCLUSION We conclude that severe sensorineural hearing loss can be induced in mice. Moreover, we found that this mouse model can be augmented via the use of rapid intravenous furosemide administrations to maximize inner hair cell loss.
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Xia L, Chen Z, Su K, Yin S, Wang J. Comparison of cochlear cell death caused by cisplatin, alone and in combination with furosemide. Toxicol Pathol 2013; 42:376-85. [PMID: 23548607 DOI: 10.1177/0192623313483213] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Establishment of appropriate animal models is an important step in exploring the mechanisms of drug-induced ototoxicity. In the present study, using guinea pigs we compared cochlear lesions induced by cisplatin administered in two regimens: consecutive application alone and in combination with furosemide. The effects of furosemide alone were also evaluated; it was found to cause temporary hearing loss and reversible damage to the stria vascularis. Consecutive application of cisplatin alone appeared to be disadvantageous because it resulted in progressive body weight loss and higher mortality compared to the combined regimen, which used a smaller cisplatin dose. The combined regimen resulted in comparable hearing loss and hair cell loss but a markedly lower mortality. However, their coadministration failed to cause similar damage to spiral ganglion neurons (SGN), as seen in animals that received cisplatin alone. This difference suggests that the combined regimen did not mimic the damage to cochlear neuronal innervation caused by the clinical application of cisplatin. The difference also suggests that the SGN lesion is not caused by cisplatin entering the cochlea via the stria vascularis.
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Affiliation(s)
- Li Xia
- 1Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
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22
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Abstract
One million patients are hospitalized each year with acute decompensated heart failure, and up to 20% of these patients are rehospitalized within a month after the acute presentation. Acute heart failure (AHF) accounts for 50,000 deaths annually and is the most frequent reason for hospital admissions in the United States. This article reviews the therapeutic options and the results of recent clinical trials in the treatment of AHF. Most patients can be effectively managed by use of diuretic agents or diuretics in combinations with nitrates, IV nitroglycerin, IV nitroprusside, and possibly IV nesiritide. Ultrafiltration is a promising technique that can be very helpful in the resistant patient. However, given the ease of initiation of diuretic therapy, it is unlikely that ultrafiltration would supplant diuretic use in acutely symptomatic patients. Patients in acute distress with AHF almost invariably respond to diuretics or a vasodilator combined with diuretic therapy. The loop diuretics are the most effective diuretics and thus most frequently used agents in treating AHF. Currently, there are 4 loop diuretics in the US market: furosemide, bumetanide, torsemide, and ethacrynic acid. IV furosemide and ethacrynic acid have a prompt venous dilatory effect, consequently decrease left ventricular filling pressure and immediately relieve symptoms of pulmonary congestion, before a diuresis can occur. Furosemide is more often used than ethacrynic acid due to its reduced ototoxic potential. However, ethacrynic acid should be used in sulfa-sensitive patients because ethacrynic acid is the only loop diuretic, which does not contain a sulfa moiety.
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23
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Abstract
Ethacrynic acid (Edecrin) is a loop diuretic that produces a prompt and profound diuresis. The primary action of ethacrynic acid is the inhibition of the activity of the Na⁺-K⁺-2Cl⁻ symporter in the thick ascending limb of the loop of Henle. The onset of action is usually within 30 minutes after an oral dose and within 5 minutes after an intravenous injection. After oral administration, peak diuretic effect occurs in about 2 hours and the effect lasts about 6-8 hours. After intravenous administration, peak diuretic effect occurs within 30 minutes and the diuretic effect is virtually completed in 2-4 hours. The bioavailability of ethacrynic acid approximates 100%, with maximal blood level between 40 and 92 minutes. The elimination half-life has been reported to be less than 1 hour, but highly variable (average 30 minutes with a range of 12-160 minutes). Intravenous ethacrynic acid has a prompt venous dilatory effect and immediately relieves symptoms of pulmonary congestion, before a diuresis can occur. Ethacrynic acid is effective in all types of edema whether there is clinical acidosis, alkalosis, or electrolyte imbalance. Most side effects of ethacrynic acid can be attributed to its effectiveness (volume depletion); however, it may cause metabolic alkalosis that is preventable by KCl replacement. Ethacrynic acid has ototoxic effect that occasionally results in temporally or permanent deafness. Despite limitations, ethacrynic acid has been employed in the treatment of congestive heart failure and other edematous states, especially in patients allergic to sulfa-containing drugs because all the other loop diuretics have a sulfa moiety.
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Dong Y, Shi JR. [Biological research evaluating the Chinese medical theory of the association of the kidney with the ears]. ACTA ACUST UNITED AC 2012; 10:128-34. [PMID: 22313879 DOI: 10.3736/jcim20120202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
"Association of the kidney with the ears" is central to the traditional Chinese medical (TCM) theory of the viscera and their manifestations. Previous studies have shown that thyroxin, aldosterone, calcium and iron might be the material basis of the correlation between the kidney and the ears. Due to restriction in research techniques and methods, there has been no further progress in this research field, whose modern biological mechanisms and scientific connotations have not been explained clearly. In recent years, the progress of biological techniques and research on kidney essence provided promising opportunities for research of the association between the kidney and the ears. This article summarized the study progress of "association of the kidney with the ears" theory and posed some meaningful study thoughts. Presbycusis is a kind of degenerative disease caused by aging, which is one aspect of aging of the human body. Because aging is considered as physiological "kidney deficiency", presbycusis can be regarded as a model of "kidney deficiency" deafness. In conclusion, investigating the correlation between "kidney deficiency" and presbycusis using biotechnology systems combined with "essence of kidney", should provide a sound basis for study of the theory of the relationship between the kidney and the ears. This will provide new and valuable information for the modern biological research about the theory of visceral associations in TCM.
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Affiliation(s)
- Yang Dong
- Experimental Teaching Center, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
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Dalian D, Haiyan J, Yong F, Salvi R, Someya S, Tanokura M. OTOTOXIC EFFECTS OF CARBOPLATIN IN ORGANOTYPIC CULTURES IN CHINCHILLAS AND RATS. J Otol 2012; 7:92-101. [PMID: 25593588 DOI: 10.1016/s1672-2930(12)50023-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Carboplatin, a second-generation platinum chemotherapeutic drug, is considerably less ototoxic than cisplatin. While common laboratory species such as mice, guinea pigs and rats are highly resistant to carboplatin ototoxicity, the chinchilla stands out as highly susceptible. Moreover, carboplatin causes an unusual gradient of cell death in chinchillas. Moderate doses selectively damage type I spiral ganglion neurons (SGN) and inner hair cells (IHC) and the lesion tends to be relatively uniform along the length of the cochlea. Higher doses eventually damage outer hair cells (OHC), but the lesion follows the traditional gradient in which damage is more severe in the base than the apex. While carboplatin ototoxicity has been well documented in adult animals in vivo, little is known about its in vitro toxicity. To elucidate the ototoxic effects of carboplatin in vitro, we prepared cochlear and vestibular organotypic cultures from postnatal day 3 rats and adult chinchillas. Chinchilla cochlear and vestibular cultures were treated with carboplatin concentrations ranging from 50 µM to 10 mM for 48 h. Consistent with in vivo data, carboplatin selectively damaged IHC at low concentrations (50-100 µM). Surprisingly, IHC loss decreased at higher doses and IHC were intact at doses exceeding 500 µM. The mechanisms underlying this nonlinear response are unclear but could be related to a decrease in carboplatin uptake via active transport mechanisms (e.g., copper). Unlike the cochlea, the carboplatin dose-response function increased with dose with the highest dose destroying all chinchilla vestibular hair cells. Cochlear hair cells and auditory nerve fibers in rat cochlear organotypic cultures were unaffected by carboplatin concentrations <10 µM; however, the damage in OHC were more severe than IHC once the dose reached 100 µM. A dose at 500 µM destroyed all the cochlear hair cells, but hair cell loss decreased at high concentrations and nearly all the cochlear hair cells were present at the highest dose, 5 mM. Unlike the nonlinear dose-response seen with cochlear hair cells, rat auditory nerve fiber and spiral ganglion losses increased with doses above 50 µM with the highest dose destroying virtually all SGN. The remarkable species differences seen in vitro suggest that chinchilla IHC and type I SGN posse some unique biological mechanism that makes them especially vulnerable to carboplatin toxicity.
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Affiliation(s)
- Ding Dalian
- Center for Hearing and Deafness, State University of New York at Buffalo ; Graduate School of Agricultural and Life Sciences, University of Tokyo
| | - Jiang Haiyan
- Center for Hearing and Deafness, State University of New York at Buffalo
| | - Fu Yong
- Center for Hearing and Deafness, State University of New York at Buffalo
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo
| | - Shinichi Someya
- Departments of Aging and Geriatric Research, Division of Biology of Aging, University of Florida
| | - Masaru Tanokura
- Graduate School of Agricultural and Life Sciences, University of Tokyo
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Liu H, Ding DL, Jiang HY, Wu XW, Salvi R, Sun H. Ototoxic destruction by co-administration of kanamycin and ethacrynic acid in rats. J Zhejiang Univ Sci B 2012; 12:853-61. [PMID: 21960349 DOI: 10.1631/jzus.b1100040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is well known that ethacrynic acid (EA) can potentiate the ototoxicity of aminoglycoside antibiotics (AmAn) such as kanamycin (KM), if they were applied at the same time. Currently, to create the model of EA-KM-induced cochlear lesion in rats, adult rats received a single injection of EA (75 mg/kg, intravenous injection), or followed immediately by KM (500 mg/kg, intramuscular injection). The hearing function was assessed by auditory brainstem response (ABR) measurement in response to click and/or tone bursts at 4, 8, 12, 16, 20, 24, and 32 kHz. The static microcirculation status in the stria vascularis after a single EA injection was evaluated with eosin staining. The pathological changes in cochlear and vestibular hair cells were also quantified after co-administration of EA and KM. After a single EA injection, blood flow in vessels supplying the stria vascularis rapidly diminished. However, the blood supply to the cochlear lateral wall partially recovered 5 h after EA treatment. Threshold changes in ABR were basically parallel to the microcirculation changes in stria vascularis after single EA treatment. Importantly, disposable co-administration of EA and KM resulted in a permanent hearing loss and severe damage to the cochlear hair cells, but spared the vestibular hair cells. Since the cochlear lateral wall is the important part of the blood-cochlea barrier, EA-induced anoxic damage to the epithelium of stria vascularis may enhance the entry of KM to the cochlea. Thus, experimental animal model of selective cochlear damage with normal vestibular systems can be reliably created through co-administration of EA and KM.
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Affiliation(s)
- Hong Liu
- Center for Hearing and Deafness, University at Buffalo, State University of New York, NY 14214, USA
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Kraus KS, Ding D, Jiang H, Lobarinas E, Sun W, Salvi RJ. Relationship between noise-induced hearing-loss, persistent tinnitus and growth-associated protein-43 expression in the rat cochlear nucleus: does synaptic plasticity in ventral cochlear nucleus suppress tinnitus? Neuroscience 2011; 194:309-25. [PMID: 21821100 PMCID: PMC3390756 DOI: 10.1016/j.neuroscience.2011.07.056] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/22/2011] [Accepted: 07/23/2011] [Indexed: 10/17/2022]
Abstract
Aberrant, lesion-induced neuroplastic changes in the auditory pathway are believed to give rise to the phantom sound of tinnitus. Noise-induced cochlear damage can induce extensive fiber growth and synaptogenesis in the cochlear nucleus, but it is currently unclear if these changes are linked to tinnitus. To address this issue, we unilaterally exposed nine rats to narrow-band noise centered at 12 kHz at 126 dB sound pressure level (SPL) for 2 h and sacrificed them 10 weeks later for evaluation of synaptic plasticity (growth-associated protein 43 [GAP-43] expression) in the cochlear nucleus. Noise-exposed rats along with three age-matched controls were screened for tinnitus-like behavior with gap prepulse inhibition of the acoustic startle (GPIAS) before, 1-10 days after, and 8-10 weeks after the noise exposure. All nine noise-exposed rats showed similar patterns of severe hair cell loss at high- and mid-frequency regions in the exposed ear. Eight of the nine showed strong up-regulation of GAP-43 in auditory nerve fibers and pronounced shrinkage of the ventral cochlear nucleus (VCN) on the noise-exposed side, and strong up-regulation of GAP-43 in the medial ventral VCN, but not in the lateral VCN or the dorsal cochlear nucleus. GAP-43 up-regulation in VCN was significantly greater in Noise-No-Tinnitus rats than in Noise-Tinnitus rats. One Noise-No-Tinnitus rat showed no up-regulation of GAP-43 in auditory nerve fibers and only little VCN shrinkage, suggesting that auditory nerve degeneration plays a role in tinnitus generation. Our results suggest that noise-induced tinnitus is suppressed by strong up-regulation of GAP-43 in the medial VCN. GAP-43 up-regulation most likely originates from medial olivocochlear neurons. Their increased excitatory input on inhibitory neurons in VCN may possibly reduce central hyperactivity and tinnitus.
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Affiliation(s)
- Kari Suzanne Kraus
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
| | - Dalian Ding
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
| | - Haiyan Jiang
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
| | - Ed Lobarinas
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
| | - Wei Sun
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
| | - Richard J Salvi
- Center for Hearing and Deafness, SUNY at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States
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Li Y, Ding D, Jiang H, Fu Y, Salvi R. Co-administration of cisplatin and furosemide causes rapid and massive loss of cochlear hair cells in mice. Neurotox Res 2011; 20:307-19. [PMID: 21455790 DOI: 10.1007/s12640-011-9244-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 03/10/2011] [Accepted: 03/21/2011] [Indexed: 12/24/2022]
Abstract
The expanding arsenal of transgenic mice has created a powerful tool for investigating the biological mechanisms involved in ototoxicity. However, cisplatin ototoxicity is difficult to investigate in mice because of their small size and vulnerability to death by nephrotoxicity. To overcome this problem, we developed a strategy for promoting cisplatin-induced ototoxicity by coadministration of furosemide a loop diuretic. A dose-response study identified 200 mg/kg of furosemide as the optimal dose for disrupting the stria vascularis and opening the blood-ear barrier. Our analysis of stria pathology indicated that the optimal period for administering cisplatin was 1 h after furosemide treatment. Combined treatment with 0.5 mg/kg of cisplatin and 200 mg/kg furosemide resulted in only moderate loss of outer hair cells in the basal 20% of the cochlea, only mild threshold shifts and minimal loss of distortion product otoacoustic emission (DPOAE). In contrast, 1 mg/kg of cisplatin plus 200 mg/kg of furosemide resulted in a permanent 40-50 dB elevation of auditory brainstem response thresholds, almost complete elimination of DPOAE, and nearly total loss of outer hair cells. The widespread outer hair cell lesions that develop in mice treated with cisplatin plus furosemide could serve as extremely useful murine model for investigating techniques for regenerating outer hair cells, studying the mechanisms of cisplatin and furosemide ototoxicity and assessing the perceptual and electrophysiological consequences of outer hair cell loss on central auditory plasticity.
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Affiliation(s)
- Yongqi Li
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, USA
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Kraus KS, Mitra S, Jimenez Z, Hinduja S, Ding D, Jiang H, Gray L, Lobarinas E, Sun W, Salvi RJ. Noise trauma impairs neurogenesis in the rat hippocampus. Neuroscience 2010; 167:1216-26. [PMID: 20206235 DOI: 10.1016/j.neuroscience.2010.02.071] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 02/24/2010] [Accepted: 02/24/2010] [Indexed: 12/31/2022]
Abstract
The hippocampus, a major site of neurogenesis in the adult brain, plays an important role in memory. Based on earlier observations where exposure to high-intensity noise not only caused hearing loss but also impaired memory function, it is conceivably that noise exposure may suppress hippocampal neurogenesis. To evaluate this possibility, nine rats were unilaterally exposed for 2 h to a high-intensity, narrow band of noise centered at 12 kHz at 126 dB SPL. The rats were also screened for noise-induced tinnitus, a potential stressor which may suppress neurogenesis. Five rats developed persistent tinnitus-like behavior while the other four rats showed no signs of tinnitus. Age-matched sham controls showed no signs of hearing loss or tinnitus. The inner ear and hippocampus were evaluated for sensory hair cell loss and neurogenesis 10 weeks post-exposure. All noise exposed rats showed severe loss of sensory hair cells in the noise-exposed ear, but essentially no damage in the unexposed ear. Frontal sections from the hippocampus were immunolabeled for doublecortin to identify neuronal precursor cells, or Ki67 to label proliferating cells. Noise-exposed rats showed a significant reduction of neuronal precursors and fewer dividing cells as compared to sham controls. However, we could not detect any difference between rats with behavioral evidence of tinnitus versus rats without tinnitus. These results show for the first time that high intensity noise exposure not only damages the cochlea but also causes a significant and persistent decrease in hippocampal neurogenesis that may contribute to functional deficits in memory.
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Affiliation(s)
- K S Kraus
- Center for Hearing and Deafness, 137 Cary Hall, University at Buffalo, Buffalo, NY 14214, USA.
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Ding D, Jiang H, Salvi RJ. Mechanisms of rapid sensory hair-cell death following co-administration of gentamicin and ethacrynic acid. Hear Res 2009; 259:16-23. [PMID: 19715747 DOI: 10.1016/j.heares.2009.08.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 08/19/2009] [Accepted: 08/20/2009] [Indexed: 10/20/2022]
Abstract
Concurrent administration of a high dose of gentamicin (GM; 125mg/kg IM) and ethacrynic acid (EA; 40mg/kg IV) results in rapid destruction of virtually all cochlear hair cells; however, the cell death signaling pathways underlying this rapid form of hair-cell degeneration are unclear. To elucidate the mechanisms underlying GM/EA-mediated cell death, several key cell death markers were assessed in the chinchilla cochlea during the early stages of degeneration. In the middle and basal turns of the cochlea, massive hair-cell loss including destruction of the stereocilia and cuticular plate occurred 12h after GM/EA treatment. Condensation and fragmentation of outer hair-cell nuclei, morphological features of apoptosis, were first observed 5-6h post-treatment in the basal turn of the cochlea. Metabolic function, reflected by succinate dehydrogenase histochemistry and mitochondrial staining, decreased significantly in the basal turn 4h following GM/EA treatment; these early changes were accompanied by the release of cytochrome c from the mitochondria into the cytosol and intense expression of initiator caspase-9 and effector caspase-3. GM/EA failed to induce expression of extrinsic initiator caspase-8. These results suggest that the rapid loss of hair cells following GM/EA treatment involves cell death pathways mediated by mitochondrial dysfunction leading to the release of cytochrome c, activation of initiator caspase-9 and effector caspase-3.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, Dept. of Communicative Disorders and Sciences, 137 Cary Hall, University at Buffalo, Buffalo, NY 14214, USA
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31
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Baldwin KA, Budzinski CE, Shapiro CJ. Acute Sensorineural Hearing Loss: Furosemide Ototoxicity Revisited. Hosp Pharm 2008. [DOI: 10.1310/hpj4312-982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ding D, Jiang H, Wang P, Salvi R. Cell death after co-administration of cisplatin and ethacrynic acid. Hear Res 2007; 226:129-39. [PMID: 16978814 DOI: 10.1016/j.heares.2006.07.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 06/10/2006] [Accepted: 07/18/2006] [Indexed: 11/18/2022]
Abstract
Ethacrynic acid (EA) significantly enhances the ototoxic effects of cisplatin. To gain insights into the mechanisms underlying Cis/EA ototoxicity, cochleas were labeled with several apoptotic markers. Cis/EA treatment caused extensive outer hair cell (OHC) and inner hair cell (IHC) damage; OHC lesions decreased from the base towards apex of the cochlea whereas the IHC lesion was relatively constant (25-60%) along the length of the cochlea. Propidium iodide labeled OHC nuclei appeared relatively normal at 6h post-treatment, were condensed and fragmented at 12h post-treatment and were frequently missing 48 h post-treatment. Initiator caspase 8, associated with membrane death receptors, and TRADD, a protein that recruits caspase 8, were present in OHC at 6h post-treatment. Caspase 8 labeling increased from 6 to 24h, but was largely absent at 48 h post-treatment. Executioner caspase 3 and caspase 6, which lie downstream of caspase 8, were expressed in OHC 12-24h post-treatment. Initiator caspase 9, associated with mitochondrial damage, was only expressed at low levels at 48 h post-treatment. These results suggest that the rapid onset of Cis/EA induced programmed cell death is initiated by membrane death receptors associated with TRADD and caspase 8.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, USA
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Yorgason JG, Fayad JN, Kalinec F. Understanding drug ototoxicity: molecular insights for prevention and clinical management. Expert Opin Drug Saf 2006; 5:383-99. [PMID: 16610968 DOI: 10.1517/14740338.5.3.383] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ototoxicity is a trait shared by aminoglycoside and macrolide antibiotics, loop diuretics, platinum-based chemotherapeutic agents, some NSAIDs and antimalarial medications. Because their benefits in combating certain life-threatening diseases often outweigh the risks, the use of these ototoxic drugs cannot simply be avoided. In this review, the authors discuss some of the most frequently used ototoxic drugs and what is currently known about the cell and molecular mechanisms underlying their noxious effects. The authors also provide suggestions for the clinical management of ototoxic medications, including ototoxic detection and drug monitoring. Understanding the mechanisms of drug ototoxicity may lead to new strategies for preventing and curing drug-induced hearing loss, as well as developing new pharmacological drugs with less toxic side effects.
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Affiliation(s)
- Joshua G Yorgason
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA 90057, USA
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Robertson CMT, Tyebkhan JM, Peliowski A, Etches PC, Cheung PY. Ototoxic drugs and sensorineural hearing loss following severe neonatal respiratory failure. Acta Paediatr 2006; 95:214-23. [PMID: 16449030 DOI: 10.1080/08035250500294098] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
AIM To determine relationships between ototoxic drugs and 4-y sensorineural hearing loss (SNHL) in near-term and term survivors of severe neonatal respiratory failure. METHODS All 81 survivors of the Canadian arm of the Neonatal Inhaled Nitric Oxide Study (mortality 32, loss to follow-up 9) received loop diuretics, aminoglycosides, and neuromuscular blockers (NMB), and 50 received vancomycin as neonates. Prospective, longitudinal secondary outcome using audiological tests diagnosed late-onset, progressive SNHL in 43 (53%); not flat (sloping) in 29, flat (severe to profound) in 14. Risk for SNHL was determined. RESULTS A combination of duration of diuretic use of >14 d and average NMB dose of >0.96 mg/kg/d contributed to SNHL among survivors (odds ratio 5.2; 95% CI 1.6, 16.7). Markers of illness severity did not contribute. Dosage or duration of aminoglycosides use did not relate to SNHL. Cumulative dosages and duration of use of diuretics; NMB; use of vancomycin; and overlap of diuretics with NMB, aminoglycosides, and vancomycin individually linked to SNHL (p<0.001). CONCLUSION Overuse of loop diuretics and/or NMB contributes to SNHL after neonatal respiratory failure; markers of illness severity or the appropriate administration of aminoglycosides do not.
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Affiliation(s)
- Charlene M T Robertson
- Neonatal and Infant Follow-up Clinic, Glenrose Rehabilitation Hospital, Capital Health, Edmonton, Alberta T5G 0B7, Canada.
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McFadden SL, Ding D, Jiang H, Salvi RJ. Time course of efferent fiber and spiral ganglion cell degeneration following complete hair cell loss in the chinchilla. Brain Res 2004; 997:40-51. [PMID: 14715148 DOI: 10.1016/j.brainres.2003.10.031] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Ethacrynic acid (EA) is known to interact with aminoglycoside antibiotics such as gentamicin (GM). In the chinchilla, co-administration of GM and EA can produce hair cell lesions ranging from a small loss of outer hair cells (OHCs) in the base of the cochlea to complete destruction of all hair cells, depending on dosing parameters. Although hair cell loss has been characterized, little is known about the fate of efferent fibers or spiral ganglion neurons (SGNs) in this model. To study the time course of efferent fiber and SGN loss, chinchillas were injected with GM (125 mg/kg IM) followed immediately by EA (40 mg/kg IV). Estimates of efferent fiber loss and density changes were made after 3 days or 1, 2, 3, or 4 weeks of survival. Estimates of SGN loss and density changes were made after 15 days or 1, 2, 4, or 6 months of survival. Cochlear function was rapidly abolished and all cochlear hair cells were missing within 24 h after treatment. Inner hair cells (IHCs) in the middle turn of the cochlea died earlier than cells in the apex or base, and OHCs in Rows 1 and 2 died earlier than OHCs in Row 3. Degeneration of efferent nerve fibers began 3-7 days post-injection, versus 15-30 days for SGNs, and the loss of efferent fibers was essentially complete within 1 month, versus 2-4 months for SGNs. The rapid time course of efferent fiber and SGN loss in the chinchilla may make it a practical model for studying mechanisms of neural loss and survival in the mammalian inner ear.
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Affiliation(s)
- Sandra L McFadden
- Center for Hearing and Deafness, University at Buffalo, 215 Parker Hall, Buffalo, NY 14214, USA.
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Abstract
Although it is well known that ethacrynic acid (EA) can enhance gentamicin (GM) ototoxicity, there has been no systematic study of the relationship between dosing parameters and inner ear pathology. We examined the effects of two parameters, GM dose and time delay between GM and EA administration, on cochlear and vestibular hair cell loss in chinchillas. 'No delay' groups received one injection of GM (125, 40, 20, or 10 mg/kg i.m.) followed immediately by EA (40 mg/kg i.v.); 'delay' groups received GM (10 mg/kg i.m.) followed by EA 1 or 1.5 h later. Animals were sacrificed 7 days later for evaluation of hair cell loss in the cochlea and vestibular end organs (cristae, saccule and utricle). Vestibular function was assessed prior to sacrifice by measuring the duration of nystagmus induced by cold caloric stimulation. No delay groups had approximately 100% loss of outer hair cells and dose-dependent losses of inner hair cells, ranging from approximately 100% to 58%. In 1 and 1.5 h delay groups, inner hair cell losses were approximately 19% and 0%, outer hair cell losses were approximately 74% and 47%, and outer hair cell loss followed a typical base to apex gradient. Two results were remarkable. First, the three groups with partial inner hair cell loss showed an atypical lesion pattern in which losses were substantially greater in the apical half than in the basal half of the cochlea. Second, there was no vestibular pathology in any group. The results establish dosing parameters that can be used to produce animal models with defined patterns and magnitudes of cochlear hair cell damage, but normal vestibular function and morphology.
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Affiliation(s)
- Sandra L McFadden
- Center for Hearing and Deafness, 215 Parker Hall, University at Buffalo, Buffalo, NY 14214, USA.
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