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Peng X, Mao Y, Tai Y, Luo B, Dai Q, Wang X, Wang H, Liang Y, Guan R, Liu C, Guo Y, Chen L, Zhang Z, Wang H. Characterization of Anxiety-Like Behaviors and Neural Circuitry following Chronic Moderate Noise Exposure in Mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2023; 131:107004. [PMID: 37796530 PMCID: PMC10552915 DOI: 10.1289/ehp12532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 08/13/2023] [Accepted: 09/06/2023] [Indexed: 10/06/2023]
Abstract
BACKGROUND Commonly encountered nontraumatic, moderate noise is increasingly implicated in anxiety; however, the neural substrates underlying this process remain unclear. OBJECTIVES We investigated the neural circuit mechanism through which chronic exposure to moderate-level noise causes anxiety-like behaviors. METHODS Mice were exposed to chronic, moderate white noise [85 decibel (dB) sound pressure level (SPL)], 4 h/d for 4 wk to induce anxiety-like behaviors, which were assessed by open field, elevated plus maze, light-dark box, and social interaction tests. Viral tracing, immunofluorescence confocal imaging, and brain slice patch-clamp recordings were used to characterize projections from auditory brain regions to the lateral amygdala. Neuronal activities were characterized by in vivo multielectrode and fiber photometry recordings in awake mice. Optogenetics and chemogenetics were used to manipulate specific neural circuitry. RESULTS Mice chronically (4 wk) exposed to moderate noise (85 dB SPL, 4 h/d) demonstrated greater neuronal activity in the lateral amygdala (LA), and the LA played a critical role in noise-induced anxiety-like behavior in these model mice. Viral tracing showed that the LA received monosynaptic projections from the medial geniculate body (MG) and auditory cortex (ACx). Optogenetic excitation of the MG → LA or ACx → LA circuits acutely evoked anxiety-like behaviors, whereas their chemogenetic inactivation abolished noise-induced anxiety-like behavior. Moreover, mice chronically exposed to moderate noise were more susceptible to acute stress, with more neuronal firing in the LA, even after noise withdrawal. DISCUSSION Mice exposed to 4 wk of moderate noise (85 dB SPL, 4 h/d) demonstrated behavioral and physiological differences compared to controls. The neural circuit mechanisms involved greater excitation from glutamatergic neurons of the MG and ACx to LA neurons under chronic, moderate noise exposure, which ultimately promoted anxiety-like behaviors. Our findings support the hypothesis that nontraumatic noise pollution is a potentially serious but unrecognized public health concern. https://doi.org/10.1289/EHP12532.
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Affiliation(s)
- Xiaoqi Peng
- Department of Anesthesiology, The First Affiliated Hospital of University of Science and Technology of China (USTC), Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yunfeng Mao
- Department of Anesthesiology, The First Affiliated Hospital of University of Science and Technology of China (USTC), Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yingju Tai
- Department of Anesthesiology, The First Affiliated Hospital of University of Science and Technology of China (USTC), Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Bin Luo
- Auditory Research Laboratory, Department of Neurobiology and Biophysics, Division of Life Sciences and Medicine, USTC, Hefei, China
- Department of Psychiatry, The First Affiliated Hospital of USTC, Hefei, China
| | - Qian Dai
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, China
| | - Xiyang Wang
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, China
| | - Hao Wang
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, China
| | - Yue Liang
- Department of Otolaryngology, The First Affiliated Hospital of USTC, Hefei, China
| | - Ruirui Guan
- Department of Otolaryngology, The First Affiliated Hospital of USTC, Hefei, China
| | - Chunhua Liu
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Yiping Guo
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Lin Chen
- Auditory Research Laboratory, Department of Neurobiology and Biophysics, Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Zhi Zhang
- Department of Anesthesiology, The First Affiliated Hospital of University of Science and Technology of China (USTC), Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Haitao Wang
- Department of Anesthesiology, The First Affiliated Hospital of University of Science and Technology of China (USTC), Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, China
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Zahra G, Esmaeil K, Mohammad F, Rashidy-Pour A, Mahdi M, Mahdi A, Ali K. Combined effects of the exposure to silver nanoparticles and noise on hearing function and cochlea structure of the male rats. Life Sci 2022; 304:120724. [PMID: 35718234 DOI: 10.1016/j.lfs.2022.120724] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/22/2022] [Accepted: 06/14/2022] [Indexed: 11/24/2022]
Abstract
AIMS This study intended to investigate whether exposure to the combination of noise and Ag-NPs in rats induces cochlear damage and hearing dysfunction. MAIN METHODS A total of 24Wistar rats were divided into four treatment groups and received/exposed to saline (IP), Ag-NPs (100 mg/kg, 5d/w for 4 weeks), 8 kHz narrowband noise (104 dB SPL, 6 h/day, 5d/w for 4 weeks) and Ag-NPs plus noise. The DPOAE, serum levels of MDA and SOD and changes in body weight were assessed. The rat cochlea was further stained for investigating the mRNA expression (TL-6, NOX3, and TNF-), IHC (TUJ-1 and MHC7), and histological alterations. The Ag-NPs characteristics were also analysed by SEM and XRD. KEY FINDINGS DPOAE values were remarkably reduced (p < 0.05) among the exposed groups. Furthermore, exposure to noise and Ag-NPs significantly increased MDA levels and decreased the SOD activity in the serum. In comparison to the control group, the expression of IL-6, TNF-, and NOX3 was shown to be elevated in the Ag-NPs plus noise group. The body weight also increased significantly in all groups with the exception of the Ag-NPs plus noise group. IHC tests showed remarkable down-regulation of TUJ1 and MYO7A. Morphological changes confirmed our findings as well. SEM and XRD data validated the production of Ag-NPs. SIGNIFICANCE According to the findings of this study, sub-acute exposure to noise and Ag-NPs causes permanent damage to the hair cells that are in charge of high-frequency perception.
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Affiliation(s)
- Goodarzi Zahra
- Department of Occupational Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Karami Esmaeil
- Department of Occupational Health Engineering, School of Health, Tehran University of medical sciences, Tehran, Iran
| | - Faridan Mohammad
- Environmental Health Research Center, Department of Occupational Health and Safety at Work Engineering, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Ali Rashidy-Pour
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran
| | - Mohammadi Mahdi
- Health Promotion Research Center, Zahedan University of Medical Science, Zahedan, Iran
| | - Akbari Mahdi
- Audiology Department Rehabilitation Faculty, Iran University of Medical Science, Tehran, Iran
| | - Khavanin Ali
- Department of Occupational Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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Hearing Loss and Cognitive Impairment: Epidemiology, Common Pathophysiological Findings, and Treatment Considerations. Life (Basel) 2021; 11:life11101102. [PMID: 34685474 PMCID: PMC8538578 DOI: 10.3390/life11101102] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 10/04/2021] [Accepted: 10/15/2021] [Indexed: 12/04/2022] Open
Abstract
In recent years, there has been increasing research interest in the correlation between hearing impairment and cognitive decline, two conditions that have demonstrated a strong association. Hearing loss appears as a risk factor for cognitive impairment, especially among certain populations, notably nursing home residents. Furthermore, hearing loss has been identified as a modifiable age-related condition linked to dementia, and it has been estimated that midlife hearing loss, if eliminated, might decrease the risk of dementia in the general population. Several mechanisms have been suggested to explain the pathologic connections between hearing loss and dementia; however, clear evidence is missing, and the common pathophysiological basis is still unclear. In this review, we discussed current knowledge about the relationship between hearing loss and dementia, and future perspectives in terms of the effects of hearing rehabilitation for early prevention of cognitive decline.
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Occelli F, Hasselmann F, Bourien J, Puel JL, Desvignes N, Wiszniowski B, Edeline JM, Gourévitch B. Temporal Alterations to Central Auditory Processing without Synaptopathy after Lifetime Exposure to Environmental Noise. Cereb Cortex 2021; 32:1737-1754. [PMID: 34494109 DOI: 10.1093/cercor/bhab310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 11/13/2022] Open
Abstract
People are increasingly exposed to environmental noise through the cumulation of occupational and recreational activities, which is considered harmless to the auditory system, if the sound intensity remains <80 dB. However, recent evidence of noise-induced peripheral synaptic damage and central reorganizations in the auditory cortex, despite normal audiometry results, has cast doubt on the innocuousness of lifetime exposure to environmental noise. We addressed this issue by exposing adult rats to realistic and nontraumatic environmental noise, within the daily permissible noise exposure limit for humans (80 dB sound pressure level, 8 h/day) for between 3 and 18 months. We found that temporary hearing loss could be detected after 6 months of daily exposure, without leading to permanent hearing loss or to missing synaptic ribbons in cochlear hair cells. The degraded temporal representation of sounds in the auditory cortex after 18 months of exposure was very different from the effects observed after only 3 months of exposure, suggesting that modifications to the neural code continue throughout a lifetime of exposure to noise.
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Affiliation(s)
- Florian Occelli
- NeuroScience Paris-Saclay Institute (NeuroPSI), CNRS, University of Paris-Saclay, Orsay F-91405, France
| | - Florian Hasselmann
- Institute for Neurosciences of Montpellier (INM), INSERM, University of Montpellier, Montpellier F-34091, France
| | - Jérôme Bourien
- Institute for Neurosciences of Montpellier (INM), INSERM, University of Montpellier, Montpellier F-34091, France
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), INSERM, University of Montpellier, Montpellier F-34091, France
| | - Nathalie Desvignes
- NeuroScience Paris-Saclay Institute (NeuroPSI), CNRS, University of Paris-Saclay, Orsay F-91405, France
| | - Bernadette Wiszniowski
- NeuroScience Paris-Saclay Institute (NeuroPSI), CNRS, University of Paris-Saclay, Orsay F-91405, France
| | - Jean-Marc Edeline
- NeuroScience Paris-Saclay Institute (NeuroPSI), CNRS, University of Paris-Saclay, Orsay F-91405, France
| | - Boris Gourévitch
- NeuroScience Paris-Saclay Institute (NeuroPSI), CNRS, University of Paris-Saclay, Orsay F-91405, France.,Institut de l'Audition, Institut Pasteur, INSERM, Paris F-75012, France.,CNRS, France
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Vijayasarathy S, Mohan M, Nagalakshmi P, Barman A. Speech perception in noise, gap detection and amplitude modulation detection in suspected hidden hearing loss. HEARING, BALANCE AND COMMUNICATION 2021. [DOI: 10.1080/21695717.2021.1876494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Srikar Vijayasarathy
- Department of Audiology, All India Institute of Speech and Hearing, Mysuru, India
| | - Meghana Mohan
- Department of Audiology, All India Institute of Speech and Hearing, Mysuru, India
| | - Pratibha Nagalakshmi
- Department of Audiology, All India Institute of Speech and Hearing, Mysuru, India
| | - Animesh Barman
- Department of Audiology, All India Institute of Speech and Hearing, Mysuru, India
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Jeng JY, Harasztosi C, Carlton A, Corns L, Marchetta P, Johnson SL, Goodyear RJ, Legan KP, Rüttiger L, Richardson GP, Marcotti W. MET currents and otoacoustic emissions from mice with a detached tectorial membrane indicate the extracellular matrix regulates Ca 2+ near stereocilia. J Physiol 2021; 599:2015-2036. [PMID: 33559882 PMCID: PMC7612128 DOI: 10.1113/jp280905] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/03/2021] [Indexed: 10/11/2023] Open
Abstract
KEY POINTS The aim was to determine whether detachment of the tectorial membrane (TM) from the organ of Corti in Tecta/Tectb-/- mice affects the biophysical properties of cochlear outer hair cells (OHCs). Tecta/Tectb-/- mice have highly elevated hearing thresholds, but OHCs mature normally. Mechanoelectrical transducer (MET) channel resting open probability (Po ) in mature OHC is ∼50% in endolymphatic [Ca2+ ], resulting in a large standing depolarizing MET current that would allow OHCs to act optimally as electromotile cochlear amplifiers. MET channel resting Po in vivo is also high in Tecta/Tectb-/- mice, indicating that the TM is unlikely to statically bias the hair bundles of OHCs. Distortion product otoacoustic emissions (DPOAEs), a readout of active, MET-dependent, non-linear cochlear amplification in OHCs, fail to exhibit long-lasting adaptation to repetitive stimulation in Tecta/Tectb-/- mice. We conclude that during prolonged, sound-induced stimulation of the cochlea the TM may determine the extracellular Ca2+ concentration near the OHC's MET channels. ABSTRACT The tectorial membrane (TM) is an acellular structure of the cochlea that is attached to the stereociliary bundles of the outer hair cells (OHCs), electromotile cells that amplify motion of the cochlear partition and sharpen its frequency selectivity. Although the TM is essential for hearing, its role is still not fully understood. In Tecta/Tectb-/- double knockout mice, in which the TM is not coupled to the OHC stereocilia, hearing sensitivity is considerably reduced compared with that of wild-type animals. In vivo, the OHC receptor potentials, assessed using cochlear microphonics, are symmetrical in both wild-type and Tecta/Tectb-/- mice, indicating that the TM does not bias the hair bundle resting position. The functional maturation of hair cells is also unaffected in Tecta/Tectb-/- mice, and the resting open probability of the mechanoelectrical transducer (MET) channel reaches values of ∼50% when the hair bundles of mature OHCs are bathed in an endolymphatic-like Ca2+ concentration (40 μM) in vitro. The resultant large MET current depolarizes OHCs to near -40 mV, a value that would allow optimal activation of the motor protein prestin and normal cochlear amplification. Although the set point of the OHC receptor potential transfer function in vivo may therefore be determined primarily by endolymphatic Ca2+ concentration, repetitive acoustic stimulation fails to produce adaptation of MET-dependent otoacoustic emissions in vivo in the Tecta/Tectb-/- mice. Therefore, the TM is likely to contribute to the regulation of Ca2+ levels around the stereocilia, and thus adaptation of the OHC MET channel during prolonged sound stimulation.
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Affiliation(s)
- Jing-Yi Jeng
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Csaba Harasztosi
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Adam Carlton
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Laura Corns
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Philine Marchetta
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Stuart L. Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Kevin P. Legan
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Lukas Rüttiger
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Guy P. Richardson
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
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Liu X, Chen GD, Salvi R. Neuroplastic changes in auditory cortex induced by long-duration "non-traumatic" noise exposures are triggered by deficits in the neural output of the cochlea. Hear Res 2021; 404:108203. [PMID: 33618162 DOI: 10.1016/j.heares.2021.108203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/14/2021] [Accepted: 02/02/2021] [Indexed: 11/16/2022]
Abstract
Long-term exposure to moderate intensity noise that does not cause measureable hearing loss can cause striking changes in sound-evoked neural activity in auditory cortex. It is unclear if these changes originate in the cortex or result from functional deficits in the neural output of the cochlea. To explore this issue, rats were exposed for 6-weeks to 18-24 kHz noise at 45, 65 or 85 dB SPL and then compared the noise-induced changes in the cochlear compound action potential (CAP) with the neurophysiological alterations in the anterior auditory field (AAF) of auditory cortex. The 45-dB exposure, which had no effect on the cochlear CAP also had no effect on the AAF. In contrast, the 85-dB exposure greatly reduced CAP amplitudes at high frequencies, but had little or no effect on low frequencies. Despite the large reduction in high-frequency CAP neural responses, high frequency AAF neural responses (spike rate and local field potential amplitude) remained largely within normal limits, evidence of central gain compensation. AAF responses were also enhanced at the low frequencies even though CAP responses were normal; this AAF hyperactivity only occurred at low-moderate intensities (level-dependent enhanced central gain). The 65-dB exposure also caused a moderate reduction in high-frequency CAP amplitudes. Notwithstanding this cochlear loss, AAF responses were boosted into the normal range, evidence of homeostatic gain compensation. Our results suggest that the noise-induced neuroplastic changes in the auditory cortex from so-called "non-traumatic" exposures are triggered from functional deficits in the neural output of the cochlea.
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Affiliation(s)
- Xiaopeng Liu
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, 137 Cary Hall, 3435 Main Street, NY 14214, USA
| | - Guang-Di Chen
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, 137 Cary Hall, 3435 Main Street, NY 14214, USA.
| | - Richard Salvi
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, 137 Cary Hall, 3435 Main Street, NY 14214, USA
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Ding D, Manohar S, Jiang H, Salvi R. Hydroxypropyl-β-cyclodextrin causes massive damage to the developing auditory and vestibular system. Hear Res 2020; 396:108073. [PMID: 32956992 DOI: 10.1016/j.heares.2020.108073] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/03/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022]
Abstract
2-hydroxypropyl-β-cyclodextrin (HPβCD), a cholesterol chelator used to treat Niemann-Pick C1 (NPC1) lysosomal storage disease, causes hearing loss in mammals by preferentially destroying outer hair cells. Because cholesterol plays an important role in early neural development, we hypothesized that HPβCD would cause more extensive damage to postnatal cochlear and vestibular structures in than adult rats. This hypothesis was tested by administering HPβCD to adult rats and postnatal day 3 (P3) cochlear and vestibular organ cultures. Adult rats treated with HPβCD developed hearing impairment and outer hair cell loss 3-day post-treatment; damage increased with dose from the high frequency base toward the low-frequency apex. The HPβCD-induced histopathologies were more severe and widespread in cochlear and vestibular cultures at P3 than in adults. HPβCD destroyed both outer and inner hair cells, auditory nerve fibers and spiral ganglion neurons as well as type I and type II vestibular hair cells and vestibular ganglion neurons. The early stage of HPβCD damage involved disruption of hair cell mechanotransduction and destruction of stereocilia. HPβCD-mediated apoptosis in P3 cultures was most-strongly initiated by activation of the extrinsic caspase-8 cell death pathway in cochlear and vestibular hair cells and neurons followed by activation of executioner caspase-3. Thus, HPβCD is toxic to all types of postnatal cochlear and vestibular hair cells and neurons in vitro whereas in vivo it only appears to destroy outer hair cells in adult cochleae. The more severe HPβCD-induced damage in postnatal cultures could be due to greater drug bioavailability in vitro and/or greater vulnerability of the developing inner ear.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, United States
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, United States
| | - Haiyan Jiang
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, United States
| | - Richard Salvi
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, United States.
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Liu X, Li L, Chen GD, Salvi R. How low must you go? Effects of low-level noise on cochlear neural response. Hear Res 2020; 392:107980. [DOI: 10.1016/j.heares.2020.107980] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 10/24/2022]
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Novel oral multifunctional antioxidant prevents noise-induced hearing loss and hair cell loss. Hear Res 2020; 388:107880. [PMID: 31945692 DOI: 10.1016/j.heares.2019.107880] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/09/2019] [Accepted: 12/27/2019] [Indexed: 12/20/2022]
Abstract
Oxidative stress is a major contributor to noise-induced hearing loss, the most common cause of hearing loss among military personnel and young adults. HK-2 is a potent, orally-active, multifunctional, redox-modulating drug that has been shown to protect against a wide range of neurological disorders with no observed side effects. HK-2 protected cochlear HEI-OC1 cells against various forms of experimentally-induced oxidative stressors similar to those observed during and after intense noise exposure. The mechanisms by which HK-2 protects cells is twofold, first by its ability to reduce oxidative stress generated by free radicals, and second, by its ability to complex biologically active transition metals such as Fe+2, thus reducing their availability to participate in the Fenton reaction where highly toxic hydroxyl radicals are generated. For the rat in vivo studies, HK-2 provided significant protection against noise-induced hearing loss and hair cell loss. Noise-induced hearing loss was induced by an 8-16 kHz octave band noises presented for 8 h/d for 21 days at an intensity of 95 dB SPL. In the Prevention study, HK-2 was administered orally beginning 5 days before the start of the noise and ending 10 days after the noise. Treatment with HK-2 dose-dependently reduced the amount of noise-induced hearing impairment, reflected in the cochlear compound action potential, and noise-induced hair cell loss. In a subsequent Rescue experiment in which HK-2 was administered for 10 days starting after the noise was turned off, HK-2 also significantly reduced the amount of hearing impairment, but the effect size was substantially less than in the Prevention studies. HK-2 alone did not adversely affect HEI-OC1 cell viability, nor did it cause any adverse changes in rat body weight, behavior, cochlear function or hair cell integrity. Thus, HK-2 is a novel, safe, orally-deliverable and highly effective otoprotective compound with considerable potential for preventing hearing loss from noise and other hearing disorders linked to excessive oxidative stress.
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Escabi CD, Frye MD, Trevino M, Lobarinas E. The rat animal model for noise-induced hearing loss. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3692. [PMID: 31795685 PMCID: PMC7480078 DOI: 10.1121/1.5132553] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Rats make excellent models for the study of medical, biological, genetic, and behavioral phenomena given their adaptability, robustness, survivability, and intelligence. The rat's general anatomy and physiology of the auditory system is similar to that observed in humans, and this has led to their use for investigating the effect of noise overexposure on the mammalian auditory system. The current paper provides a review of the rat model for studying noise-induced hearing loss and highlights advancements that have been made using the rat, particularly as these pertain to noise dose and the hazardous effects of different experimental noise types. In addition to the traditional loss of auditory function following acoustic trauma, recent findings have indicated the rat as a useful model in observing alterations in neuronal processing within the central nervous system following noise injury. Furthermore, the rat provides a second animal model when investigating noise-induced cochlear synaptopathy, as studies examining this in the rat model resemble the general patterns observed in mice. Together, these findings demonstrate the relevance of this animal model for furthering the authors' understanding of the effects of noise on structural, anatomical, physiological, and perceptual aspects of hearing.
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Affiliation(s)
- Celia D Escabi
- Callier Center for Communication Disorders, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
| | - Mitchell D Frye
- Callier Center for Communication Disorders, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
| | - Monica Trevino
- Callier Center for Communication Disorders, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
| | - Edward Lobarinas
- Callier Center for Communication Disorders, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
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