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Dörje NM, Shvachiy L, Kück F, Outeiro TF, Strenzke N, Beutner D, Setz C. Age-related alterations in efferent medial olivocochlear-outer hair cell and primary auditory ribbon synapses in CBA/J mice. Front Cell Neurosci 2024; 18:1412450. [PMID: 38988659 PMCID: PMC11234844 DOI: 10.3389/fncel.2024.1412450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 05/23/2024] [Indexed: 07/12/2024] Open
Abstract
Introduction Hearing decline stands as the most prevalent single sensory deficit associated with the aging process. Giving compelling evidence suggesting a protective effect associated with the efferent auditory system, the goal of our study was to characterize the age-related changes in the number of efferent medial olivocochlear (MOC) synapses regulating outer hair cell (OHC) activity compared with the number of afferent inner hair cell ribbon synapses in CBA/J mice over their lifespan. Methods Organs of Corti of 3-month-old CBA/J mice were compared with mice aged between 10 and 20 months, grouped at 2-month intervals. For each animal, one ear was used to characterize the synapses between the efferent MOC fibers and the outer hair cells (OHCs), while the contralateral ear was used to analyze the ribbon synapses between inner hair cells (IHCs) and type I afferent nerve fibers of spiral ganglion neurons (SGNs). Each cochlea was separated in apical, middle, and basal turns, respectively. Results The first significant age-related decline in afferent IHC-SGN ribbon synapses was observed in the basal cochlear turn at 14 months, the middle turn at 16 months, and the apical turn at 18 months of age. In contrast, efferent MOC-OHC synapses in CBA/J mice exhibited a less pronounced loss due to aging which only became significant in the basal and middle turns of the cochlea by 20 months of age. Discussion This study illustrates an age-related reduction on efferent MOC innervation of OHCs in CBA/J mice starting at 20 months of age. Our findings indicate that the morphological decline of efferent MOC-OHC synapses due to aging occurs notably later than the decline observed in afferent IHC-SGN ribbon synapses.
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Affiliation(s)
- Nele Marie Dörje
- University Medical Center Göttingen, Department of Otolaryngology-Head and Neck Surgery, InnerEarLab, Göttingen, Germany
- University Medical Center Göttingen, Institute for Auditory Neuroscience, Göttingen, Germany
| | - Liana Shvachiy
- University Medical Center Göttingen, Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
- Institute of Physiology, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Cardiovascular Centre, University of Lisbon, Lisbon, Portugal
| | - Fabian Kück
- University Medical Center Göttingen, Department of Medical Statistics, Core Facility Medical Biometry and Statistical Bioinformatics, Göttingen, Germany
| | - Tiago F Outeiro
- University Medical Center Göttingen, Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Nicola Strenzke
- University Medical Center Göttingen, Institute for Auditory Neuroscience, Göttingen, Germany
| | - Dirk Beutner
- University Medical Center Göttingen, Department of Otolaryngology-Head and Neck Surgery, InnerEarLab, Göttingen, Germany
| | - Cristian Setz
- University Medical Center Göttingen, Department of Otolaryngology-Head and Neck Surgery, InnerEarLab, Göttingen, Germany
- University Medical Center Göttingen, Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
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Steenken F, Pektaş A, Köppl C. Age-related changes in olivocochlear efferent innervation in gerbils. Front Synaptic Neurosci 2024; 16:1422330. [PMID: 38887655 PMCID: PMC11180762 DOI: 10.3389/fnsyn.2024.1422330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 05/20/2024] [Indexed: 06/20/2024] Open
Abstract
Introduction Age-related hearing difficulties have a complex etiology that includes degenerative processes in the sensory cochlea. The cochlea comprises the start of the afferent, ascending auditory pathway, but also receives efferent feedback innervation by two separate populations of brainstem neurons: the medial olivocochlear and lateral olivocochlear pathways, innervating the outer hair cells and auditory-nerve fibers synapsing on inner hair cells, respectively. Efferents are believed to improve hearing under difficult conditions, such as high background noise. Here, we compare olivocochlear efferent innervation density along the tonotopic axis in young-adult and aged gerbils (at ~50% of their maximum lifespan potential), a classic animal model for age-related hearing loss. Methods Efferent synaptic terminals and sensory hair cells were labeled immunohistochemically with anti-synaptotagmin and anti-myosin VIIa, respectively. Numbers of hair cells, numbers of efferent terminals, and the efferent innervation area were quantified at seven tonotopic locations along the organ of Corti. Results The tonotopic distribution of olivocochlear innervation in the gerbil was similar to that previously shown for other species, with a slight apical cochlear bias in presumed lateral olivocochlear innervation (inner-hair-cell region), and a broad mid-cochlear peak for presumed medial olivocochlear innervation (outer-hair-cell region). We found significant, age-related declines in overall efferent innervation to both the inner-hair-cell and the outer-hair-cell region. However, when accounting for the age-related losses in efferent target structures, the innervation density of surviving elements proved unchanged in the inner-hair-cell region. For outer hair cells, a pronounced increase of orphaned outer hair cells, i.e., lacking efferent innervation, was observed. Surviving outer hair cells that were still efferently innervated retained a nearly normal innervation. Discussion A comparison across species suggests a basic aging scenario where outer hair cells, type-I afferents, and the efferents associated with them, steadily die away with advancing age, but leave the surviving cochlear circuitry largely intact until an advanced age, beyond 50% of a species' maximum lifespan potential. In the outer-hair-cell region, MOC degeneration may precede outer-hair-cell death, leaving a putatively transient population of orphaned outer hair cells that are no longer under efferent control.
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Affiliation(s)
- Friederike Steenken
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence “Hearing4all”, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Asli Pektaş
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Christine Köppl
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence “Hearing4all”, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Centre Neurosensory Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
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Fuentes-Santamaría V, Benítez-Maicán Z, Alvarado JC, Fernández Del Campo IS, Gabaldón-Ull MC, Merchán MA, Juiz JM. Surface electrical stimulation of the auditory cortex preserves efferent medial olivocochlear neurons and reduces cochlear traits of age-related hearing loss. Hear Res 2024; 447:109008. [PMID: 38636186 DOI: 10.1016/j.heares.2024.109008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/19/2024] [Accepted: 04/11/2024] [Indexed: 04/20/2024]
Abstract
The auditory cortex is the source of descending connections providing contextual feedback for auditory signal processing at almost all levels of the lemniscal auditory pathway. Such feedback is essential for cognitive processing. It is likely that corticofugal pathways are degraded with aging, becoming important players in age-related hearing loss and, by extension, in cognitive decline. We are testing the hypothesis that surface, epidural stimulation of the auditory cortex during aging may regulate the activity of corticofugal pathways, resulting in modulation of central and peripheral traits of auditory aging. Increased auditory thresholds during ongoing age-related hearing loss in the rat are attenuated after two weeks of epidural stimulation with direct current applied to the surface of the auditory cortex for two weeks in alternate days (Fernández del Campo et al., 2024). Here we report that the same cortical electrical stimulation protocol induces structural and cytochemical changes in the aging cochlea and auditory brainstem, which may underlie recovery of age-degraded auditory sensitivity. Specifically, we found that in 18 month-old rats after two weeks of cortical electrical stimulation there is, relative to age-matched non-stimulated rats: a) a larger number of choline acetyltransferase immunoreactive neuronal cell body profiles in the ventral nucleus of the trapezoid body, originating the medial olivocochlear system.; b) a reduction of age-related dystrophic changes in the stria vascularis; c) diminished immunoreactivity for the pro-inflammatory cytokine TNFα in the stria vascularis and spiral ligament. d) diminished immunoreactivity for Iba1 and changes in the morphology of Iba1 immunoreactive cells in the lateral wall, suggesting reduced activation of macrophage/microglia; d) Increased immunoreactivity levels for calretinin in spiral ganglion neurons, suggesting excitability modulation by corticofugal stimulation. Altogether, these findings support that non-invasive neuromodulation of the auditory cortex during aging preserves the cochlear efferent system and ameliorates cochlear aging traits, including stria vascularis dystrophy, dysregulated inflammation and altered excitability in primary auditory neurons.
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Affiliation(s)
- V Fuentes-Santamaría
- School of Medicine, Universidad de Castilla-La Mancha (UCLM), Campus in Albacete, 02008, Albacete, Spain
| | - Z Benítez-Maicán
- School of Medicine, Universidad de Castilla-La Mancha (UCLM), Campus in Albacete, 02008, Albacete, Spain
| | - J C Alvarado
- School of Medicine, Universidad de Castilla-La Mancha (UCLM), Campus in Albacete, 02008, Albacete, Spain
| | - I S Fernández Del Campo
- Lab. of Auditory Neuroplasticity, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain
| | - M C Gabaldón-Ull
- School of Medicine, Universidad de Castilla-La Mancha (UCLM), Campus in Albacete, 02008, Albacete, Spain
| | - M A Merchán
- Lab. of Auditory Neuroplasticity, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain
| | - J M Juiz
- School of Medicine, Universidad de Castilla-La Mancha (UCLM), Campus in Albacete, 02008, Albacete, Spain; Hannover Medical School, Dept. of Otolaryngology and Cluster of Excellence "H4all" of the German Research Foundation, DFG, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
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Mondul JA, Burke K, Morley B, Lauer AM. Alpha9alpha10 knockout mice show altered physiological and behavioral responses to signals in masking noise. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:3183-3194. [PMID: 38738939 PMCID: PMC11093617 DOI: 10.1121/10.0025985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 04/24/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024]
Abstract
Medial olivocochlear (MOC) efferents modulate outer hair cell motility through specialized nicotinic acetylcholine receptors to support encoding of signals in noise. Transgenic mice lacking the alpha9 subunits of these receptors (α9KOs) have normal hearing in quiet and noise, but lack classic cochlear suppression effects and show abnormal temporal, spectral, and spatial processing. Mice deficient for both the alpha9 and alpha10 receptor subunits (α9α10KOs) may exhibit more severe MOC-related phenotypes. Like α9KOs, α9α10KOs have normal auditory brainstem response (ABR) thresholds and weak MOC reflexes. Here, we further characterized auditory function in α9α10KO mice. Wild-type (WT) and α9α10KO mice had similar ABR thresholds and acoustic startle response amplitudes in quiet and noise, and similar frequency and intensity difference sensitivity. α9α10KO mice had larger ABR Wave I amplitudes than WTs in quiet and noise. Other ABR metrics of hearing-in-noise function yielded conflicting findings regarding α9α10KO susceptibility to masking effects. α9α10KO mice also had larger startle amplitudes in tone backgrounds than WTs. Overall, α9α10KO mice had grossly normal auditory function in quiet and noise, although their larger ABR amplitudes and hyperreactive startles suggest some auditory processing abnormalities. These findings contribute to the growing literature showing mixed effects of MOC dysfunction on hearing.
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Affiliation(s)
- Jane A Mondul
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Kali Burke
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Barbara Morley
- Boys Town National Research Hospital, Omaha, Nebraska 68131, USA
| | - Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Mondul JA, Burke K, Morley B, Lauer AM. Alpha9alpha10 knockout mice show altered physiological and behavioral responses to signals in masking noise. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.567909. [PMID: 38045351 PMCID: PMC10690178 DOI: 10.1101/2023.11.21.567909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Medial olivocochlear (MOC) efferents modulate outer hair cell motility through specialized nicotinic acetylcholine receptors to support encoding of signals in noise. Transgenic mice lacking the alpha9 subunits of these receptors (α9KOs) have normal hearing in quiet and noise, but lack classic cochlear suppression effects and show abnormal temporal, spectral, and spatial processing. Mice deficient for both the alpha9 and alpha10 receptor subunits (α9α10KOs) may exhibit more severe MOC-related phenotypes. Like α9KOs, α9α10KOs have normal auditory brainstem response (ABR) thresholds and weak MOC reflexes. Here, we further characterized auditory function in α9α10KO mice. Wildtype and α9α10KO mice had similar ABR thresholds and acoustic startle response (ASR) amplitudes in quiet and noise, and similar frequency and intensity difference sensitivity. α9α10KO mice had larger ABR Wave I amplitudes than wildtypes in quiet and noise, but the noise:quiet amplitude ratio suggested α9α10KOs were more susceptible to masking effects for some stimuli. α9α10KO mice also had larger startle amplitudes in tone backgrounds than wildtypes. Overall, α9α10KO mice had grossly normal auditory function in quiet and noise, though their larger ABR amplitudes and hyperreactive startles suggest some auditory processing abnormalities. These findings contribute to the growing literature showing mixed effects of MOC dysfunction on hearing.
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Vicencio-Jimenez S, Delano PH, Madrid N, Terreros G, Maass JC, Delgado C, Jorratt P. Maintained Spatial Learning and Memory Functions in Middle-Aged α9 Nicotinic Receptor Subunit Knock-Out Mice. Brain Sci 2023; 13:brainsci13050794. [PMID: 37239266 DOI: 10.3390/brainsci13050794] [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: 04/03/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
Age-related hearing loss is linked to cognitive impairment, but the mechanisms that relate to these conditions remain unclear. Evidence shows that the activation of medial olivocochlear (MOC) neurons delays cochlear aging and hearing loss. Consequently, the loss of MOC function may be related to cognitive impairment. The α9/α10 nicotinic receptor is the main target of cholinergic synapses between the MOC neurons and cochlear outer hair cells. Here, we explored spatial learning and memory performance in middle-aged wild-type (WT) and α9-nAChR subunit knock-out (KO) mice using the Barnes maze and measured auditory brainstem response (ABR) thresholds and the number of cochlear hair cells as a proxy of cochlear aging. Our results show non-significant spatial learning differences between WT and KO mice, but KO mice had a trend of increased latency to enter the escape box and freezing time. To test a possible reactivity to the escape box, we evaluated the novelty-induced behavior using an open field and found a tendency towards more freezing time in KO mice. There were no differences in memory, ABR threshold, or the number of cochlear hair cells. We suggest that the lack of α9-nAChR subunit alters novelty-induced behavior, but not spatial learning in middle-aged mice, by a non-cochlear mechanism.
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Affiliation(s)
- Sergio Vicencio-Jimenez
- Departamento de Neurociencia, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
- Biomedical Neuroscience Institute, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
- Otolaryngology Department, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Paul H Delano
- Departamento de Neurociencia, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
- Biomedical Neuroscience Institute, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
- Department of Otolaryngology, Hospital Clínico Universidad de Chile, Santiago 8320328, Chile
- Centro Avanzado de Ingeniería Eléctrica y Electrónica, AC3E, Universidad Técnica Federico Santa María, Valparaíso 2390136, Chile
| | - Natalia Madrid
- Departamento de Neurociencia, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
| | - Gonzalo Terreros
- Instituto de Ciencias de la Salud, Universidad de O'Higgins, Rancagua 2841935, Chile
| | - Juan C Maass
- Department of Otolaryngology, Hospital Clínico Universidad de Chile, Santiago 8320328, Chile
- Interdisciplinary Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago 8320328, Chile
| | - Carolina Delgado
- Departamento de Neurociencia, Facultad de Medicina, Universidad de Chile, Santiago 8320328, Chile
| | - Pascal Jorratt
- National Institute of Mental Health, Topolová 748, 250 67 Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic
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Holtmann LC, Strahlenbach A, Hans S, Jung L, Lang S, Eichler T, Arweiler-Harbeck D. Assessing Medial Olivocochlear Reflex Strengths via Auditory Brainstem Response: Measurement and Variability in Normal-Hearing Individuals. Am J Audiol 2023; 32:220-231. [PMID: 36729649 DOI: 10.1044/2022_aja-22-00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Optimal measurement settings to measure the medial olivocochlear reflex (MOCR) in humans have not yet been defined. The purpose of this study was to advance the representation of the MOCR in auditory brainstem response (ABR) as an addition to the current diagnostic portfolio. PARTICIPANTS AND METHOD Twelve female and 14 male normal-hearing adults participated in the study. Potential effects of a contralateral acoustic stimulus (CAS) on amplitude changes were investigated by recording ABR waveform profiles on the left side at click intensities of 50/60/70 dB nHL with and without CAS (60 dB SPL). Secondly, to detect potential chronological order influences, measurement settings were rearranged on the right side and measurements were repeated. Additionally, ABR thresholds were recorded with and without a CAS in 10 patients. RESULTS When the effect of contralateral suppression was analyzed on the basis of amplitude changes, there was a change under administration of the CAS signal that was statistically significant. Interestingly, the order of recordings affected the degree of amplitude change. In three out of 10 patients, reproducible suppression effects on ABR thresholds were detectable upon CAS presentation. CONCLUSIONS To our knowledge, this is the largest study dealing with the recording of the MOCR elicited by a contralateral noise via ABR in normal-hearing individuals. Effects of MOCR are measurable via amplitude changes upon CAS administration. Chronological orders influence the impact of this effect on amplitude changes. Optimal measurement settings have not yet been defined. However, experiments such as this study may help to further improve measurements, and thus advance the representation of the MOC reflex in ABR as an addition to the current diagnostic portfolio.
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Affiliation(s)
- Laura Christine Holtmann
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
| | - Amadea Strahlenbach
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
| | - Stefan Hans
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
| | - Lea Jung
- Cochlear Implant Centrum Ruhr, Bagus Service and ReHabilitation, Essen, Germany
| | - Stephan Lang
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
| | - Theda Eichler
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
| | - Diana Arweiler-Harbeck
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Essen, University of Duisburg-Essen, Germany
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Chequer Charan D, Hua Y, Wang H, Huang W, Wang F, Elgoyhen AB, Boergens KM, Di Guilmi MN. Volume electron microscopy reveals age-related circuit remodeling in the auditory brainstem. Front Cell Neurosci 2022; 16:1070438. [PMID: 36589288 PMCID: PMC9799098 DOI: 10.3389/fncel.2022.1070438] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/21/2022] [Indexed: 12/23/2022] Open
Abstract
The medial nucleus of the trapezoid body (MNTB) is an integral component of the auditory brainstem circuitry involved in sound localization. The giant presynaptic nerve terminal with multiple active zones, the calyx of Held (CH), is a hallmark of this nucleus, which mediates fast and synchronized glutamatergic synaptic transmission. To delineate how these synaptic structures adapt to reduced auditory afferents due to aging, we acquired and reconstructed circuitry-level volumes of mouse MNTB at different ages (3 weeks, 6, 18, and 24 months) using serial block-face electron microscopy. We used C57BL/6J, the most widely inbred mouse strain used for transgenic lines, which displays a type of age-related hearing loss. We found that MNTB neurons reduce in density with age. Surprisingly we observed an average of approximately 10% of poly-innervated MNTB neurons along the mouse lifespan, with prevalence in the low frequency region. Moreover, a tonotopy-dependent heterogeneity in CH morphology was observed in young but not in older mice. In conclusion, our data support the notion that age-related hearing impairments can be in part a direct consequence of several structural alterations and circuit remodeling in the brainstem.
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Affiliation(s)
- Daniela Chequer Charan
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, INGEBI-CONICET, Buenos Aires, Argentina
| | - Yunfeng Hua
- Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Haoyu Wang
- Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenqing Huang
- Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fangfang Wang
- Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, INGEBI-CONICET, Buenos Aires, Argentina
| | - Kevin M. Boergens
- Department of Physics, The University of Illinois at Chicago, Chicago, IL, United States,*Correspondence: Kevin M. Boergens Mariano N. Di Guilmi
| | - Mariano N. Di Guilmi
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, INGEBI-CONICET, Buenos Aires, Argentina,*Correspondence: Kevin M. Boergens Mariano N. Di Guilmi
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Capshaw G, Vicencio-Jimenez S, Screven LA, Burke K, Weinberg MM, Lauer AM. Physiological Evidence for Delayed Age-related Hearing Loss in Two Long-lived Rodent Species (Peromyscus leucopus and P. californicus). J Assoc Res Otolaryngol 2022; 23:617-631. [PMID: 35882705 PMCID: PMC9613845 DOI: 10.1007/s10162-022-00860-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/30/2022] [Indexed: 10/16/2022] Open
Abstract
Deer mice (genus Peromyscus) are an emerging model for aging studies due to their longevity relative to rodents of similar size. Although Peromyscus species are well-represented in genetic, developmental, and behavioral studies, relatively few studies have investigated auditory sensitivity in this genus. Given the potential utility of Peromyscus for investigations of age-related changes to auditory function, we recorded auditory brainstem responses (ABRs) in two Peromyscus species, P. californicus, and P. leucopus, across the lifespan. We compared hearing sensitivity and ABR wave metrics measured in these species with measurements from Mus musculus (CBA/CaJ strain) to assess age-related effects on hearing across species. Recordings in young animals showed that all species had similar hearing ranges and thresholds with peak sensitivity ranging from 8 to 16 kHz; however, P. californicus and P. leucopus were more sensitive to frequencies below 8 kHz. Although M. musculus showed significant threshold shifts across a broad range of frequencies beginning at middle age and worsening among old individuals, older Peromyscus mice retained good sensitivity to sound across their lifespan. Middle-aged P. leucopus had comparable thresholds to young for frequencies below 24 kHz. P. leucopus also had notably large ABRs that were robust to age-related amplitude reductions, although response latencies increased with age. Old P. californicus were less sensitive to mid-range tones (8-16 kHz) than young individuals; however, there were no significant age-effects on ABR amplitudes or latencies in this species. These results indicate that longevity in Peromyscus mice may be correlated with delayed aging of the auditory system and highlight these species as promising candidates for longitudinal hearing research.
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Affiliation(s)
- Grace Capshaw
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD USA
| | - Sergio Vicencio-Jimenez
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Laurel A. Screven
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Kali Burke
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Madison M. Weinberg
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Amanda M. Lauer
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
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Grierson KE, Hickman TT, Liberman MC. Dopaminergic and cholinergic innervation in the mouse cochlea after noise-induced or age-related synaptopathy. Hear Res 2022; 422:108533. [PMID: 35671600 PMCID: PMC11195664 DOI: 10.1016/j.heares.2022.108533] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/11/2022] [Accepted: 05/20/2022] [Indexed: 11/17/2022]
Abstract
Cochlear synaptopathy, the loss of or damage to connections between auditory-nerve fibers (ANFs) and inner hair cells (IHCs), is a prominent pathology in noise-induced and age-related hearing loss. Here, we investigated if degeneration of the olivocochlear (OC) efferent innervation is also a major aspect of the synaptopathic ear, by quantifying the volume and spatial organization of its cholinergic and dopaminergic components, using antibodies to vesicular acetylcholine transporter (VAT) and tyrosine hydroxylase (TH), respectively. CBA/CaJ male mice were examined 1 day to 8 months after a synaptopathic noise exposure, and compared to unexposed age-matched controls and unexposed aged mice at 24-28 months. In normal ears, cholinergic lateral (L)OC terminals were denser in the apical half of the cochlea and on the modiolar side of the inner hair cells (IHCs), where ANFs of low-spontaneous rate are typically found, while dopaminergic terminals were more common in the basal third of the cochlea and, re the IHC axes, were offset towards the habenula with respect to cholinergic terminals. The noise had only small and transient effects on the density of LOC innervation, its spatial organization around the IHC axes, or the extent to which TH and VAT signal were colocalized. The synaptopathic noise also had relatively small and transient effects on cholinergic innervation density in the outer hair cell (OHC) area, which normally peaks in the 16 kHz region and falls monotonically towards higher and lower frequencies. In contrast, in the aged ears, there was massive degeneration of OHC efferents, especially in the apical half of the cochlea, where there was also significant loss of OHCs. In the IHC area, there was significant loss of cholinergic terminals in both apical and basal regions and of dopaminergic innervation in the basal half. Furthermore, the cholinergic terminals in the aged ears spread from their normal clustering near the IHC basolateral pole, where the ANF synapses are found, to positions up and down the IHC somata and regions of the neuropil closer to the habenula. This apparent migration was most striking in the apex, where the hair cell pathology was greatest, and may be a harbinger of impending hair cell death.
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Affiliation(s)
- Kiera E Grierson
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, 02114 USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115 USA; Hearing Research Lab, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, AUS
| | - Tyler T Hickman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, 02114 USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115 USA.
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, 02114 USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115 USA
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Sadeghi SG, Géléoc GSG. Editorial: Commonalities and Differences in Vestibular and Auditory Pathways. Front Neurosci 2022; 16:876798. [PMID: 35401079 PMCID: PMC8984178 DOI: 10.3389/fnins.2022.876798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 02/24/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Soroush G. Sadeghi
- Center for Hearing and Deafness, Department of Communicative Disorders and Science, University at Buffalo, Buffalo, NY, United States
- *Correspondence: Soroush G. Sadeghi
| | - Gwenaëlle S. G. Géléoc
- Boston Children's Hospital and Harvard Medical School, Boston, MA, United States
- Gwenaëlle S. G. Géléoc
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