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Hong H, Koo EJ, Park Y, Song G, Joo SY, Kim JA, Gee HY, Jung J, Park K, Han GC, Choie JY, Kim SH. Vestibular hair cells are more prone to damage by excessive acceleration insult in the mouse with KCNQ4 dysfunction. Sci Rep 2024; 14:15260. [PMID: 38956136 PMCID: PMC11219875 DOI: 10.1038/s41598-024-66115-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 06/27/2024] [Indexed: 07/04/2024] Open
Abstract
KCNQ4 is a voltage-gated K+ channel was reported to distribute over the basolateral surface of type 1 vestibular hair cell and/or inner surface of calyx and heminode of the vestibular nerve connected to the type 1 vestibular hair cells of the inner ear. However, the precise localization of KCNQ4 is still controversial and little is known about the vestibular phenotypes caused by KCNQ4 dysfunction or the specific role of KCNQ4 in the vestibular organs. To investigate the role of KCNQ4 in the vestibular organ, 6-g hypergravity stimulation for 24 h, which represents excessive mechanical stimulation of the sensory epithelium, was applied to p.W277S Kcnq4 transgenic mice. KCNQ4 was detected on the inner surface of calyx of the vestibular afferent in transmission electron microscope images with immunogold labelling. Vestibular function decrease was more severe in the Kcnq4p.W277S/p.W277S mice than in the Kcnq4+/+ and Kcnq4+/p.W277S mice after the stimulation. The vestibular function loss was resulted from the loss of type 1 vestibular hair cells, which was possibly caused by increased depolarization duration. Retigabine, a KCNQ activator, prevented hypergravity-induced vestibular dysfunction and hair cell loss. Patients with KCNQ4 mutations also showed abnormal clinical vestibular function tests. These findings suggest that KCNQ4 plays an essential role in calyx and afferent of type 1 vestibular hair cell preserving vestibular function against excessive mechanical stimulation.
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Affiliation(s)
- Hansol Hong
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea
| | - Eun Ji Koo
- Department of Otorhinolaryngology, Gachon University College of Medicine, Incheon, Republic of Korea
| | - Yesai Park
- Department of Otorhinolaryngology, Incheon St. Mary's Hospital, Catholic University College of Medicine, Incheon, Republic of Korea
| | - Gabae Song
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea
| | - Sun Young Joo
- Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jung Ah Kim
- Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Heon Yung Gee
- Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jinsei Jung
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea
| | - Kangyoon Park
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea
| | - Gyu Cheol Han
- Department of Otorhinolaryngology, Gachon University College of Medicine, Incheon, Republic of Korea.
| | - Jae Young Choie
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea.
| | - Sung Huhn Kim
- Department of Otorhinolaryngology, Won-Sang Lee Institute for Hearing Loss, Yonsei University College of Medicine and Graduate School of Medicine, Seoul, Republic of Korea.
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Martin HR, Lysakowski A, Eatock RA. The potassium channel subunit K V1.8 ( Kcna10) is essential for the distinctive outwardly rectifying conductances of type I and II vestibular hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.21.563853. [PMID: 38045305 PMCID: PMC10690164 DOI: 10.1101/2023.11.21.563853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
In amniotes, head motions and tilt are detected by two types of vestibular hair cells (HCs) with strikingly different morphology and physiology. Mature type I HCs express a large and very unusual potassium conductance, gK,L, which activates negative to resting potential, confers very negative resting potentials and low input resistances, and enhances an unusual non-quantal transmission from type I cells onto their calyceal afferent terminals. Following clues pointing to KV1.8 (KCNA10) in the Shaker K channel family as a candidate gK,L subunit, we compared whole-cell voltage-dependent currents from utricular hair cells of KV1.8-null mice and littermate controls. We found that KV1.8 is necessary not just for gK,L but also for fast-inactivating and delayed rectifier currents in type II HCs, which activate positive to resting potential. The distinct properties of the three KV1.8-dependent conductances may reflect different mixing with other KV subunits that are reported to be differentially expressed in type I and II HCs. In KV1.8-null HCs of both types, residual outwardly rectifying conductances include KV7 (KCNQ) channels. Current clamp records show that in both HC types, KV1.8-dependent conductances increase the speed and damping of voltage responses. Features that speed up vestibular receptor potentials and non-quantal afferent transmission may have helped stabilize locomotion as tetrapods moved from water to land.
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Affiliation(s)
| | - Anna Lysakowski
- University of Illinois at Chicago, Department of Anatomy and Cell Biology
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Borrajo M, Sedano D, Palou A, Giménez-Esbrí V, Barrallo-Gimeno A, Llorens J. Maturation of type I and type II rat vestibular hair cells in vivo and in vitro. Front Cell Dev Biol 2024; 12:1404894. [PMID: 38895157 PMCID: PMC11183282 DOI: 10.3389/fcell.2024.1404894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 05/16/2024] [Indexed: 06/21/2024] Open
Abstract
Vestibular sensory epithelia contain type I and type II sensory hair cells (HCI and HCII). Recent studies have revealed molecular markers for the identification of these cells, but the precise composition of each vestibular epithelium (saccule, utricle, lateral crista, anterior crista, posterior crista) and their postnatal maturation have not been described in detail. Moreover, in vitro methods to study this maturation are not well developed. We obtained total HCI and HCII counts in adult rats and studied the maturation of the epithelia from birth (P0) to postnatal day 28 (P28). Adult vestibular epithelia hair cells were found to comprise ∼65% HCI expressing osteopontin and PMCA2, ∼30% HCII expressing calretinin, and ∼4% HCII expressing SOX2 but neither osteopontin nor calretinin. At birth, immature HCs express both osteopontin and calretinin. P28 epithelia showed an almost adult-like composition but still contained 1.3% of immature HCs. In addition, we obtained free-floating 3D cultures of the epithelia at P1, which formed a fluid-filled cyst, and studied their survival and maturation in vitro up to day 28 (28 DIV). These cultures showed good HC resiliency and maturation. Using an enriched medium for the initial 4 days, a HCI/calretinin+-HCII ratio close to the in vivo ratio was obtained. These cultures are suitable to study HC maturation and mature HCs in pharmacological, toxicological and molecular research.
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Affiliation(s)
- Mireia Borrajo
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
- Institut de Neurociències, Universitat de Barcelona (UB), Barcelona, Catalunya, Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospitalet de Llobregat, Catalunya, Spain
| | - David Sedano
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
| | - Aïda Palou
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
- Institut de Neurociències, Universitat de Barcelona (UB), Barcelona, Catalunya, Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospitalet de Llobregat, Catalunya, Spain
| | - Víctor Giménez-Esbrí
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
- Institut de Neurociències, Universitat de Barcelona (UB), Barcelona, Catalunya, Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospitalet de Llobregat, Catalunya, Spain
| | - Alejandro Barrallo-Gimeno
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
- Institut de Neurociències, Universitat de Barcelona (UB), Barcelona, Catalunya, Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospitalet de Llobregat, Catalunya, Spain
| | - Jordi Llorens
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Hospitalet de Llobregat, Catalunya, Spain
- Institut de Neurociències, Universitat de Barcelona (UB), Barcelona, Catalunya, Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospitalet de Llobregat, Catalunya, Spain
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Sinha AK, Lee C, Holt JC. KCNQ2/3 regulates efferent mediated slow excitation of vestibular afferents in mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.30.573731. [PMID: 38260489 PMCID: PMC10802244 DOI: 10.1101/2023.12.30.573731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Primary vestibular afferents transmit information from hair cells about head position and movement to the CNS, which is critical for maintaining balance, gaze stability and spatial navigation. The CNS, in turn, modulates hair cells and afferents via the efferent vestibular system (EVS) and its activation of several cholinergic signaling mechanisms. Electrical stimulation of EVS neurons gives rise to three kinetically- and mechanistically-distinct afferent responses including a slow excitation, a fast excitation, and a fast inhibition. EVS-mediated slow excitation is attributed to odd-numbered muscarinic acetylcholine receptors (mAChRs) on the afferent whose activation leads to the closure of a potassium conductance and increased afferent discharge. Likely effector candidates include low-threshold, voltage-gated potassium channels belonging to the KCNQ (Kv7.X) family, which are involved in neuronal excitability across the nervous system and are subject to mAChR modulation. Specifically, KCNQ2/3 heteromeric channels may be the molecular correlates for the M-current, a potassium current that is blocked following the activation of odd-numbered mAChRs. To this end, multiple members of the KCNQ channel family, including KCNQ2 and KCNQ3, are localized to several microdomains within vestibular afferent endings, where they influence afferent excitability and could be targeted by EVS neurons. Additionally, the relative expression of KCNQ subunits appears to vary across the sensory epithelia and among different afferent types. However, it is unclear which KCNQ channel subunits are targeted by mAChR activation and whether that also varies among different afferent classes. Here we show that EVS-mediated slow excitation is blocked and enhanced by the non-selective KCNQ channel blocker XE991 and opener retigabine, respectively. Using KCNQ subunit-selective drugs, we observed that a KCNQ2 blocker blocks the slow response in irregular afferents, while a KCNQ2/3 opener enhances slow responses in regular afferents. The KCNQ2 blockers did not appear to affect resting afferent discharge rates, while KCNQ2/3 or KCNQ2/4 openers decreased afferent excitability. Here, we show pharmacological evidence that KCNQ2/3 subunits are likely targeted by mAChR activation in mammalian vestibular afferents. Additionally, we show that KCNQ3 KO mice have altered resting discharge rate as well as EVS-mediated slow response. These data together suggest that KCNQ channels play a role in slow response and discharge rate of vestibular afferents, which can be modulated by EVS in mammals.
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Schenberg L, Palou A, Simon F, Bonnard T, Barton CE, Fricker D, Tagliabue M, Llorens J, Beraneck M. Multisensory gaze stabilization in response to subchronic alteration of vestibular type I hair cells. eLife 2023; 12:RP88819. [PMID: 38019267 PMCID: PMC10686621 DOI: 10.7554/elife.88819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023] Open
Abstract
The functional complementarity of the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) allows for optimal combined gaze stabilization responses (CGR) in light. While sensory substitution has been reported following complete vestibular loss, the capacity of the central vestibular system to compensate for partial peripheral vestibular loss remains to be determined. Here, we first demonstrate the efficacy of a 6-week subchronic ototoxic protocol in inducing transient and partial vestibular loss which equally affects the canal- and otolith-dependent VORs. Immunostaining of hair cells in the vestibular sensory epithelia revealed that organ-specific alteration of type I, but not type II, hair cells correlates with functional impairments. The decrease in VOR performance is paralleled with an increase in the gain of the OKR occurring in a specific range of frequencies where VOR normally dominates gaze stabilization, compatible with a sensory substitution process. Comparison of unimodal OKR or VOR versus bimodal CGR revealed that visuo-vestibular interactions remain reduced despite a significant recovery in the VOR. Modeling and sweep-based analysis revealed that the differential capacity to optimally combine OKR and VOR correlates with the reproducibility of the VOR responses. Overall, these results shed light on the multisensory reweighting occurring in pathologies with fluctuating peripheral vestibular malfunction.
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Affiliation(s)
- Louise Schenberg
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
| | - Aïda Palou
- Departament de Ciències Fisiològiques, Universitat de BarcelonaBarcelonaSpain
- Institut de Neurociènces, Universitat de BarcelonaBarcelonaSpain
- Institut d'Investigació Biomèdica de Bellvitge (IDIBELL)l’Hospitalet de LlobregatSpain
| | - François Simon
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
- Department of Paediatric Otolaryngology, Hôpital Necker-Enfants MaladesParisFrance
| | - Tess Bonnard
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
| | - Charles-Elliot Barton
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
| | - Desdemona Fricker
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
| | - Michele Tagliabue
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
| | - Jordi Llorens
- Departament de Ciències Fisiològiques, Universitat de BarcelonaBarcelonaSpain
- Institut de Neurociènces, Universitat de BarcelonaBarcelonaSpain
- Institut d'Investigació Biomèdica de Bellvitge (IDIBELL)l’Hospitalet de LlobregatSpain
| | - Mathieu Beraneck
- Université Paris Cité, CNRS UMR 8002, INCC - Integrative Neuroscience and Cognition CenterParisFrance
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Baeza-Loya S, Eatock RA. Effects of transient, persistent, and resurgent sodium currents on excitability and spike regularity in vestibular ganglion neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569044. [PMID: 38076890 PMCID: PMC10705474 DOI: 10.1101/2023.11.28.569044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Vestibular afferent neurons occur as two populations, regular and irregular, that provide distinct information about head motions. Differences in spike timing regularity are correlated with the different sensory responses important for vestibular processing. Relative to irregular afferents, regular afferents have more sustained firing patterns in response to depolarizing current steps, are more excitable, and have different complements of ion channels. Models of vestibular regularity and excitability emphasize the influence of increased expression of low-voltage-activated potassium currents in irregular neurons. We investigated the potential impact of different modes of voltage-gated sodium (NaV) current (transient, persistent, and resurgent) in cell bodies from vestibular ganglion neurons (VGNs), dissociated and cultured overnight. We hypothesized that regular VGNs would show the greatest impact of persistent (non-inactivating) NaV currents and of resurgent NaV currents, which flow when NaV channels are blocked and then unblocked. Whole-cell patch clamp experiments showed that much of the NaV current modes is carried by NaV1.6 channels. With simulations, we detected little substantial effect in any model VGN of persistent or resurgent modes on regularity of spike timing driven by postsynaptic current trains. For simulated irregular neurons, we also saw little effect on spike rate or firing pattern. For simulated regular VGNs, adding resurgent current changed the detailed timing of spikes during a current step, while the small persistent conductance (less than10% of transient NaV conductance density) strongly depolarized resting potential, altered spike waveform, and increased spike rate. These results suggest that persistent and resurgent NaV current can have a greater effect on the regular VGNs than on irregular VGNs, where low-voltage-activated K conductances dominate.
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Affiliation(s)
- Selina Baeza-Loya
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-HNS, University of Washington, Seattle, WA, United States
| | - Ruth Anne Eatock
- Department of Neurobiology, University of Chicago, Chicago, IL, United States
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Pastras CJ, Curthoys IS, Asadnia M, McAlpine D, Rabbitt RD, Brown DJ. Evidence That Ultrafast Nonquantal Transmission Underlies Synchronized Vestibular Action Potential Generation. J Neurosci 2023; 43:7149-7157. [PMID: 37775302 PMCID: PMC10601366 DOI: 10.1523/jneurosci.1417-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/10/2023] [Accepted: 09/13/2023] [Indexed: 10/01/2023] Open
Abstract
Amniotes evolved a unique postsynaptic terminal in the inner ear vestibular organs called the calyx that receives both quantal and nonquantal (NQ) synaptic inputs from Type I sensory hair cells. The nonquantal synaptic current includes an ultrafast component that has been hypothesized to underlie the exceptionally high synchronization index (vector strength) of vestibular afferent neurons in response to sound and vibration. Here, we present three lines of evidence supporting the hypothesis that nonquantal transmission is responsible for synchronized vestibular action potentials of short latency in the guinea pig utricle of either sex. First, synchronized vestibular nerve responses are unchanged after administration of the AMPA receptor antagonist CNQX, while auditory nerve responses are completely abolished. Second, stimulus evoked vestibular nerve compound action potentials (vCAP) are shown to occur without measurable synaptic delay and three times shorter than the latency of auditory nerve compound action potentials (cCAP), relative to the generation of extracellular receptor potentials. Third, paired-pulse stimuli designed to deplete the readily releasable pool (RRP) of synaptic vesicles in hair cells reveal forward masking in guinea pig auditory cCAPs, but a complete lack of forward masking in vestibular vCAPs. Results support the conclusion that the fast component of nonquantal transmission at calyceal synapses is indefatigable and responsible for ultrafast responses of vestibular organs evoked by transient stimuli.SIGNIFICANCE STATEMENT The mammalian vestibular system drives some of the fastest reflex pathways in the nervous system, ensuring stable gaze and postural control for locomotion on land. To achieve this, terrestrial amniotes evolved a large, unique calyx afferent terminal which completely envelopes one or more presynaptic vestibular hair cells, which transmits mechanosensory signals mediated by quantal and nonquantal (NQ) synaptic transmission. We present several lines of evidence in the guinea pig which reveals the most sensitive vestibular afferents are remarkably fast, much faster than their auditory nerve counterparts. Here, we present neurophysiological and pharmacological evidence that demonstrates this vestibular speed advantage arises from ultrafast NQ electrical synaptic transmission from Type I hair cells to their calyx partners.
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Affiliation(s)
- Christopher J Pastras
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Ian S Curthoys
- School of Psychology, Vestibular Research Laboratory, The University of Sydney, Sydney, New South Wales 2050, Australia
- Department of Linguistics, The Australian Hearing Hub, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Mohsen Asadnia
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, New South Wales 2109, Australia
| | - David McAlpine
- Department of Linguistics, The Australian Hearing Hub, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Richard D Rabbitt
- Departments of Biomedical Engineering, Otolaryngology, and Neuroscience Program, University of Utah, Salt Lake City, Utah 84112
| | - Daniel J Brown
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, Western Australia 6102, Australia
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Paplou VG, Schubert NMA, van Tuinen M, Vijayakumar S, Pyott SJ. Functional, Morphological and Molecular Changes Reveal the Mechanisms Associated with Age-Related Vestibular Loss. Biomolecules 2023; 13:1429. [PMID: 37759828 PMCID: PMC10526133 DOI: 10.3390/biom13091429] [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: 08/21/2023] [Revised: 09/08/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
Age-related loss of vestibular function and hearing are common disorders that arise from the loss of function of the inner ear and significantly decrease quality of life. The underlying pathophysiological mechanisms are poorly understood and difficult to investigate in humans. Therefore, our study examined young (1.5-month-old) and old (24-month-old) C57BL/6 mice, utilizing physiological, histological, and transcriptomic methods. Vestibular sensory-evoked potentials revealed that older mice had reduced wave I amplitudes and delayed wave I latencies, indicating reduced vestibular function. Immunofluorescence and image analysis revealed that older mice exhibited a significant decline in type I sensory hair cell density, particularly in hair cells connected to dimorphic vestibular afferents. An analysis of gene expression in the isolated vestibule revealed the upregulation of immune-related genes and the downregulation of genes associated with ossification and nervous system development. A comparison with the isolated cochlear sensorineural structures showed similar changes in genes related to immune response, chondrocyte differentiation, and myelin formation. These findings suggest that age-related vestibular hypofunction is linked to diminished peripheral vestibular responses, likely due to the loss of a specific subpopulation of hair cells and calyceal afferents. The upregulation of immune- and inflammation-related genes implies that inflammation contributes to these functional and structural changes. Furthermore, the comparison of gene expression between the vestibule and cochlea indicates both shared and distinct mechanisms contributing to age-related vestibular and hearing impairments. Further research is necessary to understand the mechanistic connection between inflammation and age-related balance and hearing disorders and to translate these findings into clinical treatment strategies.
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Affiliation(s)
- Vasiliki Georgia Paplou
- Department of Otorhinolaryngology and Head/Neck Surgery, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; (V.G.P.); (N.M.A.S.); (M.v.T.)
| | - Nick M. A. Schubert
- Department of Otorhinolaryngology and Head/Neck Surgery, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; (V.G.P.); (N.M.A.S.); (M.v.T.)
- Graduate School of Medical Sciences Research, School of Behavioural and Cognitive Neurosciences, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Marcel van Tuinen
- Department of Otorhinolaryngology and Head/Neck Surgery, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; (V.G.P.); (N.M.A.S.); (M.v.T.)
| | - Sarath Vijayakumar
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA;
| | - Sonja J. Pyott
- Department of Otorhinolaryngology and Head/Neck Surgery, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; (V.G.P.); (N.M.A.S.); (M.v.T.)
- Graduate School of Medical Sciences Research, School of Behavioural and Cognitive Neurosciences, University of Groningen, 9713 AV Groningen, The Netherlands
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Babu V, Bahari R, Laban N, Kulaga J, Abdul Z, Zakkar B, Al-Najjar A, Lesus J, Al-Rifai AAR, Sattar H, Irukulla S, Gunniya P, Requena T, Lysakowski A. RotaRod and acoustic startle reflex performance of two potential mouse models for Meniere's disease. Eur J Neurosci 2023; 58:2708-2723. [PMID: 37461313 DOI: 10.1111/ejn.16083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 06/11/2023] [Accepted: 06/17/2023] [Indexed: 08/04/2023]
Abstract
Meniere's disease (MD) is a disorder of the inner ear characterized by chronic episodes of vertigo, tinnitus, increased aural pressure, and sensorineural hearing loss. Causes of MD are unknown, but endolymphatic hydrops is a hallmark. In addition, 5%-15% of MD cases have been identified as familial. Whole-genome sequencing studies of individuals with familial MD identified DTNA and FAM136A as candidate genes for autosomal dominant inheritance of MD. Although the exact roles of these genes in MD are unknown, FAM136A encodes a mitochondrial protein, and DTNA encodes a cytoskeletal protein involved in synapse formation and maintenance, important for maintaining the blood-brain barrier. It is also associated with a particular aquaporin. We tested vestibular and auditory function in dtna and fam136a knockout (KO) mice, using RotaRod and startle reflex-based clicker tests, respectively. Three-factor analysis of variance (ANOVA) results indicated that sex, age, and genotype were significantly correlated with reduced mean latencies to fall ("latencies") for male dtna KO mice, while only age was a significant factor for fam136a KO mice. Fam136a KO mice lost their hearing months before WTs (9-11 months vs. 15-20 months). In male dtna KO mice, divergence in mean latencies compared with other genotypes was first evident at 4 months of age, with older males having an even greater decrease. Our results indicate that fam136a gene mutations generate hearing problems, while dtna gene mutations produce balance deficits. Both mouse models should help to elucidate hearing loss and balance-related symptoms associated with MD.
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Affiliation(s)
- Vidya Babu
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Rose Bahari
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Nora Laban
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Jacob Kulaga
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Zahid Abdul
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Basil Zakkar
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Ahmad Al-Najjar
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Joseph Lesus
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | | | - Heba Sattar
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Suhitha Irukulla
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Pranav Gunniya
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Teresa Requena
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Anna Lysakowski
- University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
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Maroto AF, Borrajo M, Prades S, Callejo À, Amilibia E, Pérez-Grau M, Roca-Ribas F, Castellanos E, Barrallo-Gimeno A, Llorens J. The vestibular calyceal junction is dismantled following subchronic streptomycin in rats and sensory epithelium stress in humans. Arch Toxicol 2023; 97:1943-1961. [PMID: 37195449 PMCID: PMC10256663 DOI: 10.1007/s00204-023-03518-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 05/04/2023] [Indexed: 05/18/2023]
Abstract
Hair cell (HC) loss by epithelial extrusion has been described to occur in the rodent vestibular system during chronic 3,3'-iminodipropionitrile (IDPN) ototoxicity. This is preceded by dismantlement of the calyceal junction in the contact between type I HC (HCI) and calyx afferent terminals. Here, we evaluated whether these phenomena have wider significance. First, we studied rats receiving seven different doses of streptomycin, ranging from 100 to 800 mg/kg/day, for 3-8 weeks. Streptomycin caused loss of vestibular function associated with partial loss of HCI and decreased expression of contactin-associated protein (CASPR1), denoting calyceal junction dismantlement, in the calyces encasing the surviving HCI. Additional molecular and ultrastructural data supported the conclusion that HC-calyx detachment precede HCI loss by extrusion. Animals allowed to survive after the treatment showed functional recuperation and rebuilding of the calyceal junction. Second, we evaluated human sensory epithelia obtained during therapeutic labyrinthectomies and trans-labyrinthine tumour excisions. Some samples showed abnormal CASPR1 label strongly suggestive of calyceal junction dismantlement. Therefore, reversible dismantlement of the vestibular calyceal junction may be a common response triggered by chronic stress, including ototoxic stress, before HCI loss. This may partly explain clinical observations of reversion in function loss after aminoglycoside exposure.
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Affiliation(s)
- Alberto F. Maroto
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Catalunya Spain
- Institut de Neurociènces, Universitat de Barcelona (UB), Barcelona, Catalunya Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08907 L’Hospitalet de Llobregat, Catalunya Spain
| | - Mireia Borrajo
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Catalunya Spain
- Institut de Neurociènces, Universitat de Barcelona (UB), Barcelona, Catalunya Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08907 L’Hospitalet de Llobregat, Catalunya Spain
| | - Sílvia Prades
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Catalunya Spain
| | - Àngela Callejo
- Servei d’Otorinolaringologia, Hospital Universitari Germans Trias i Pujol, Badalona, Catalunya Spain
- CSUR Phakomatoses Multidisciplinary Clinics HUGTIP-ICO-IGTP, Barcelona, Catalunya Spain
| | - Emilio Amilibia
- Servei d’Otorinolaringologia, Hospital Universitari Germans Trias i Pujol, Badalona, Catalunya Spain
- CSUR Phakomatoses Multidisciplinary Clinics HUGTIP-ICO-IGTP, Barcelona, Catalunya Spain
| | - Marta Pérez-Grau
- Servei d’Otorinolaringologia, Hospital Universitari Germans Trias i Pujol, Badalona, Catalunya Spain
- CSUR Phakomatoses Multidisciplinary Clinics HUGTIP-ICO-IGTP, Barcelona, Catalunya Spain
| | - Francesc Roca-Ribas
- Servei d’Otorinolaringologia, Hospital Universitari Germans Trias i Pujol, Badalona, Catalunya Spain
- CSUR Phakomatoses Multidisciplinary Clinics HUGTIP-ICO-IGTP, Barcelona, Catalunya Spain
| | - Elisabeth Castellanos
- CSUR Phakomatoses Multidisciplinary Clinics HUGTIP-ICO-IGTP, Barcelona, Catalunya Spain
- Clinical Genomics Research Group, Institut de Recerca Germans Trias i Pujol (IGTP), Badalona, Catalunya Spain
| | - Alejandro Barrallo-Gimeno
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Catalunya Spain
- Institut de Neurociènces, Universitat de Barcelona (UB), Barcelona, Catalunya Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08907 L’Hospitalet de Llobregat, Catalunya Spain
| | - Jordi Llorens
- Departament de Ciències Fisiològiques, Universitat de Barcelona (UB), Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Catalunya Spain
- Institut de Neurociènces, Universitat de Barcelona (UB), Barcelona, Catalunya Spain
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08907 L’Hospitalet de Llobregat, Catalunya Spain
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11
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Meredith FL, Vu TA, Gehrke B, Benke TA, Dondzillo A, Rennie KJ. Expression of hyperpolarization-activated current ( Ih) in zonally defined vestibular calyx terminals of the crista. J Neurophysiol 2023; 129:1468-1481. [PMID: 37198134 PMCID: PMC10259860 DOI: 10.1152/jn.00135.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 05/19/2023] Open
Abstract
Calyx terminals make afferent synapses with type I hair cells in vestibular epithelia and express diverse ionic conductances that influence action potential generation and discharge regularity in vestibular afferent neurons. Here we investigated the expression of hyperpolarization-activated current (Ih) in calyx terminals in central and peripheral zones of mature gerbil crista slices, using whole cell patch-clamp recordings. Slowly activating Ih was present in >80% calyces tested in both zones. Peak Ih and half-activation voltages were not significantly different; however, Ih activated with a faster time course in peripheral compared with central zone calyces. Calyx Ih in both zones was blocked by 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD7288; 100 µM), and the resting membrane potential became more hyperpolarized. In the presence of dibutyryl-cAMP (dB-cAMP), peak Ih was increased, activation kinetics became faster, and the voltage of half-activation was more depolarized compared with control calyces. In current clamp, calyces from both zones showed three different categories of firing: spontaneous firing, phasic firing where a single action potential was evoked after a hyperpolarizing pulse, or a single evoked action potential followed by membrane potential oscillations. In the absence of Ih, the latency to peak of the action potential increased; Ih produces a small depolarizing current that facilitates firing by driving the membrane potential closer to threshold. Immunostaining showed the expression of HCN2 subunits in calyx terminals. We conclude that Ih is found in calyx terminals across the crista and could influence conventional and novel forms of synaptic transmission at the type I hair cell-calyx synapse.NEW & NOTEWORTHY Calyx afferent terminals make synapses with vestibular hair cells and express diverse conductances that impact action potential firing in vestibular primary afferents. Conventional and nonconventional synaptic transmission modes are influenced by hyperpolarization-activated current (Ih), but regional differences were previously unexplored. We show that Ih is present in both central and peripheral calyces of the mammalian crista. Ih produces a small depolarizing resting current that facilitates firing by driving the membrane potential closer to threshold.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
| | - Tiffany A Vu
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
| | - Brandon Gehrke
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
| | - Timothy A Benke
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, United States
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado, United States
- Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, United States
| | - Anna Dondzillo
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
| | - Katherine J Rennie
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, United States
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12
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Wang X, Liu S, Cheng Q, Qu C, Ren R, Du H, Li N, Yan K, Wang Y, Xiong W, Xu Z. CIB2 and CIB3 Regulate Stereocilia Maintenance and Mechanoelectrical Transduction in Mouse Vestibular Hair Cells. J Neurosci 2023; 43:3219-3231. [PMID: 37001993 PMCID: PMC10162464 DOI: 10.1523/jneurosci.1807-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/20/2023] [Accepted: 03/25/2023] [Indexed: 04/03/2023] Open
Abstract
The mechanoelectrical transduction (MET) protein complex in the inner-ear hair cells is essential for hearing and balance perception. Calcium and integrin-binding protein 2 (CIB2) has been reported to be a component of MET complex, and loss of CIB2 completely abolishes MET currents in auditory hair cells, causing profound congenital hearing loss. However, loss of CIB2 does not affect MET currents in vestibular hair cells (VHCs) as well as general balance function. Here, we show that CIB2 and CIB3 act redundantly to regulate MET in VHCs, as MET currents are completely abolished in the VHCs of Cib2/Cib3 double knock-out mice of either sex. Furthermore, we show that Cib2 and Cib3 transcripts have complementary expression patterns in the vestibular maculae, and that they play different roles in stereocilia maintenance in VHCs. Cib2 transcripts are highly expressed in the striolar region, and knock-out of Cib2 affects stereocilia maintenance in striolar VHCs. In contrast, Cib3 transcripts are highly expressed in the extrastriolar region, and knock-out of Cib3 mainly affects stereocilia maintenance in extrastriolar VHCs. Simultaneous knock-out of Cib2 and Cib3 affects stereocilia maintenance in all VHCs and leads to severe balance deficits. Taken together, our present work reveals that CIB2 and CIB3 are important for stereocilia maintenance as well as MET in mouse VHCs.SIGNIFICANCE STATEMENT Calcium and integrin-binding protein 2 (CIB2) is an important component of mechanoelectrical transduction (MET) complex, and loss of CIB2 completely abolishes MET in auditory hair cells. However, MET is unaffected in Cib2 knock-out vestibular hair cells (VHCs). In the present work, we show that CIB3 could compensate for the loss of CIB2 in VHCs, and Cib2/Cib3 double knock-out completely abolishes MET in VHCs. Interestingly, CIB2 and CIB3 could also regulate VHC stereocilia maintenance in a nonredundant way. Cib2 and Cib3 transcripts are highly expressed in the striolar and extrastriolar regions, respectively. Stereocilia maintenance and balance function are differently affected in Cib2 or Cib3 knock-out mice. In conclusion, our data suggest that CIB2 and CIB3 are important for stereocilia maintenance and MET in mouse VHCs.
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Affiliation(s)
- Xiaoying Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Shuang Liu
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, People's Republic of China
- Chinese Institute for Brain Research, Beijing 102206, People's Republic of China
| | - Qi Cheng
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Chengli Qu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Rui Ren
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Nana Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Keji Yan
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Wei Xiong
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, People's Republic of China
- Chinese Institute for Brain Research, Beijing 102206, People's Republic of China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People's Republic of China
- Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, Shandong 250014, People's Republic of China
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13
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Govindaraju AC, Quraishi IH, Lysakowski A, Eatock RA, Raphael RM. Nonquantal transmission at the vestibular hair cell-calyx synapse: K LV currents modulate fast electrical and slow K + potentials. Proc Natl Acad Sci U S A 2023; 120:e2207466120. [PMID: 36595693 PMCID: PMC9926171 DOI: 10.1073/pnas.2207466120] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vestibular hair cells transmit information about head position and motion across synapses to primary afferent neurons. At some of these synapses, the afferent neuron envelopes the hair cell, forming an enlarged synaptic terminal called a calyx. The vestibular hair cell-calyx synapse supports a mysterious form of electrical transmission that does not involve gap junctions, termed nonquantal transmission (NQT). The NQT mechanism is thought to involve the flow of ions from the presynaptic hair cell to the postsynaptic calyx through low-voltage-activated channels driven by changes in cleft [K+] as K+ exits the hair cell. However, this hypothesis has not been tested with a quantitative model and the possible role of an electrical potential in the cleft has remained speculative. Here, we present a computational model that captures experimental observations of NQT and identifies features that support the existence of an electrical potential (ϕ) in the synaptic cleft. We show that changes in cleft ϕ reduce transmission latency and illustrate the relative contributions of both cleft [K+] and ϕ to the gain and phase of NQT. We further demonstrate that the magnitude and speed of NQT depend on calyx morphology and that increasing calyx height reduces action potential latency in the calyx afferent. These predictions are consistent with the idea that the calyx evolved to enhance NQT and speed up vestibular signals that drive neural circuits controlling gaze, balance, and orientation.
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Affiliation(s)
- Aravind Chenrayan Govindaraju
- aApplied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, TX77005
- bDepartment of Bioengineering, Rice University, Houston, TX77005
| | - Imran H. Quraishi
- cDepartment of Neurology, Yale University School of Medicine, New Haven, CT06510
| | - Anna Lysakowski
- dDepartment of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL60612
| | - Ruth Anne Eatock
- eDepartment of Neurobiology, University of Chicago, Chicago, IL60637
| | - Robert M. Raphael
- bDepartment of Bioengineering, Rice University, Houston, TX77005
- 1To whom correspondence may be addressed.
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14
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Mukhopadhyay M, Pangrsic T. Synaptic transmission at the vestibular hair cells of amniotes. Mol Cell Neurosci 2022; 121:103749. [PMID: 35667549 DOI: 10.1016/j.mcn.2022.103749] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 05/09/2022] [Accepted: 06/01/2022] [Indexed: 11/19/2022] Open
Abstract
A harmonized interplay between the central nervous system and the five peripheral end organs is how the vestibular system helps organisms feel a sense of balance and motion in three-dimensional space. The receptor cells of this system, much like their cochlear equivalents, are the specialized hair cells. However, research over the years has shown that the vestibular endorgans and hair cells evolved very differently from their cochlear counterparts. The structurally unique calyceal synapse, which appeared much later in the evolutionary time scale, and continues to intrigue researchers, is now known to support several forms of synaptic neurotransmission. The conventional quantal transmission is believed to employ the ribbon structures, which carry several tethered vesicles filled with neurotransmitters. However, the field of vestibular hair cell synaptic molecular anatomy is still at a nascent stage and needs further work. In this review, we will touch upon the basic structure and function of the peripheral vestibular system, with the focus on the various modes of neurotransmission at the type I vestibular hair cells. We will also shed light on the current knowledge about the molecular anatomy of the vestibular hair cell synapses and vestibular synaptopathy.
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Affiliation(s)
- Mohona Mukhopadhyay
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, and Institute for Auditory Neuroscience, 37075 Göttingen, Germany
| | - Tina Pangrsic
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, and Institute for Auditory Neuroscience, 37075 Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany; Collaborative Research Center 889, University of Göttingen, Göttingen, Germany; Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany.
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15
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Balmer TS, Trussell LO. Vestibular Organ Dissection and Whole-Mount Immunolabeling in Mouse. Bio Protoc 2022; 12:e4416. [PMID: 35813023 PMCID: PMC9183969 DOI: 10.21769/bioprotoc.4416] [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: 12/13/2021] [Revised: 03/24/2022] [Accepted: 03/28/2022] [Indexed: 12/29/2022] Open
Abstract
The vestibular sensory apparatus contained in the inner ear is a marvelous evolutionary adaptation for sensing movement in 3 dimensions and is essential for an animal's sense of orientation in space, head movement, and balance. Damage to these systems through injury or disease can lead to vertigo, Meniere's disease, and other disorders that are profoundly debilitating. One challenge in studying vestibular organs is their location within the boney inner ear and their small size, especially in mice, which have become an advantageous mammalian model. This protocol describes the dissection procedure of the five vestibular organs from the inner ear of adult mice, followed by immunohistochemical labeling of a whole mount preparation using antibodies to label endogenous proteins such as calretinin to label Type I hair cells or to amplify genetically expressed fluorescent proteins for confocal microscopic imaging. Using typical lab equipment and reagents, a patient technician, student, or postdoc can learn to dissect and immunolabel mouse vestibular organs to investigate their structure in health and disease.
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Affiliation(s)
- Timothy S. Balmer
- Vollum Institute and Oregon Hearing Research Center, Oregon Health & Science University, Portland, USA; ,*For correspondence:
| | - Laurence O. Trussell
- Vollum Institute and Oregon Hearing Research Center, Oregon Health & Science University, Portland, USA
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16
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Kim GS, Wang T, Sayyid ZN, Fuhriman J, Jones SM, Cheng AG. Repair of surviving hair cells in the damaged mouse utricle. Proc Natl Acad Sci U S A 2022; 119:e2116973119. [PMID: 35380897 PMCID: PMC9169652 DOI: 10.1073/pnas.2116973119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 02/21/2022] [Indexed: 11/18/2022] Open
Abstract
Sensory hair cells (HCs) in the utricle are mechanoreceptors required to detect linear acceleration. After damage, the mammalian utricle partially restores the HC population and organ function, although regenerated HCs are primarily type II and immature. Whether native, surviving HCs can repair and contribute to this recovery is unclear. Here, we generated the Pou4f3DTR/+; Atoh1CreERTM/+; Rosa26RtdTomato/+ mouse to fate map HCs prior to ablation. After HC ablation, vestibular evoked potentials were abolished in all animals, with ∼57% later recovering responses. Relative to nonrecovery mice, recovery animals harbored more Atoh1-tdTomato+ surviving HCs. In both groups, surviving HCs displayed markers of both type I and type II subtypes and afferent synapses, despite distorted lamination and morphology. Surviving type II HCs remained innervated in both groups, whereas surviving type I HCs first lacked and later regained calyces in the recovery, but not the nonrecovery, group. Finally, surviving HCs initially displayed immature and subsequently mature-appearing bundles in the recovery group. These results demonstrate that surviving HCs are capable of self-repair and may contribute to the recovery of vestibular function.
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Affiliation(s)
- Grace S. Kim
- Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305
| | - Tian Wang
- Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305
| | - Zahra N. Sayyid
- Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305
| | - Jessica Fuhriman
- Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305
| | - Sherri M. Jones
- Department of Special Education and Communication Disorders, College of Education and Human Sciences, University of Nebraska, Lincoln, NE 68583
| | - Alan G. Cheng
- Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305
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17
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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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18
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Lebowitz JJ, Trinkle M, Bunzow JR, Balcita-Pedicino JJ, Hetelekides S, Robinson B, De La Torre S, Aicher SA, Sesack SR, Williams JT. Subcellular localization of D2 receptors in the murine substantia nigra. Brain Struct Funct 2021; 227:925-941. [PMID: 34854963 DOI: 10.1007/s00429-021-02432-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 11/08/2021] [Indexed: 12/13/2022]
Abstract
G-protein-coupled D2 autoreceptors expressed on dopamine neurons (D2Rs) inhibit transmitter release and cell firing at axonal endings and somatodendritic compartments. Mechanistic details of somatodendritic dopamine release remain unresolved, partly due to insufficient information on the subcellular distribution of D2Rs. Previous studies localizing D2Rs have been hindered by a dearth of antibodies validated for specificity in D2R knockout animals and have been limited by the small sampling areas imaged by electron microscopy. This study utilized sub-diffraction fluorescence microscopy and electron microscopy to examine D2 receptors in a superecliptic pHlourin GFP (SEP) epitope-tagged D2 receptor knockin mouse. Incubating live slices with an anti-SEP antibody achieved the selective labeling of plasma membrane-associated receptors for immunofluorescent imaging over a large area of the substantia nigra pars compacta (SNc). SEP-D2Rs appeared as puncta-like structures along the surface of dendrites and soma of dopamine neurons visualized by antibodies to tyrosine hydroxylase (TH). TH-associated SEP-D2Rs displayed a cell surface density of 0.66 puncta/µm2, which corresponds to an average frequency of 1 punctum every 1.50 µm. Separate ultrastructural experiments using silver-enhanced immunogold revealed that membrane-bound particles represented 28% of total D2Rs in putative dopamine cells within the SNc. Structures immediately adjacent to dendritic membrane gold particles were unmyelinated axons or axon varicosities (40%), astrocytes (19%), other dendrites (7%), or profiles unidentified (34%) in single sections. Some apposed profiles also expressed D2Rs. Fluorescent and ultrastructural analyses also provided the first visualization of membrane D2Rs at the axon initial segment, a compartment critical for action potential generation. The punctate appearance of anti-SEP staining indicates there is a population of D2Rs organized in discrete signaling sites along the plasma membrane, and for the first time, a quantitative estimate of spatial frequency is provided.
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Affiliation(s)
- Joseph J Lebowitz
- Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Mason Trinkle
- Departments of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - James R Bunzow
- Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | | | - Savas Hetelekides
- Departments of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Brooks Robinson
- Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Santiago De La Torre
- Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Sue A Aicher
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Susan R Sesack
- Departments of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA.,Departments of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - John T Williams
- Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA.
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19
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Quinn RK, Drury HR, Cresswell ET, Tadros MA, Nayagam BA, Callister RJ, Brichta AM, Lim R. Expression and Physiology of Voltage-Gated Sodium Channels in Developing Human Inner Ear. Front Neurosci 2021; 15:733291. [PMID: 34759790 PMCID: PMC8575412 DOI: 10.3389/fnins.2021.733291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/29/2021] [Indexed: 11/13/2022] Open
Abstract
Sodium channel expression in inner ear afferents is essential for the transmission of vestibular and auditory information to the central nervous system. During development, however, there is also a transient expression of Na+ channels in vestibular and auditory hair cells. Using qPCR analysis, we describe the expression of four Na+ channel genes, SCN5A (Nav1.5), SCN8A (Nav1.6), SCN9A (Nav1.7), and SCN10A (Nav1.8) in the human fetal cristae ampullares, utricle, and base, middle, and apex of the cochlea. Our data show distinct patterns of Na+ channel gene expression with age and between these inner ear organs. In the utricle, there was a general trend toward fold-change increases in expression of SCN8A, SCN9A, and SCN10A with age, while the crista exhibited fold-change increases in SCN5A and SCN8A and fold-change decreases in SCN9A and SCN10A. Fold-change differences of each gene in the cochlea were more complex and likely related to distinct patterns of expression based on tonotopy. Generally, the relative expression of SCN genes in the cochlea was greater than that in utricle and cristae ampullares. We also recorded Na+ currents from developing human vestibular hair cells aged 10-11 weeks gestation (WG), 12-13 WG, and 14+ WG and found there is a decrease in the number of vestibular hair cells that exhibit Na+ currents with increasing gestational age. Na+ current properties and responses to the application of tetrodotoxin (TTX; 1 μM) in human fetal vestibular hair cells are consistent with those recorded in other species during embryonic and postnatal development. Both TTX-sensitive and TTX-resistant currents are present in human fetal vestibular hair cells. These results provide a timeline of sodium channel gene expression in inner ear neuroepithelium and the physiological characterization of Na+ currents in human fetal vestibular neuroepithelium. Understanding the normal developmental timeline of ion channel gene expression and when cells express functional ion channels is essential information for regenerative technologies.
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Affiliation(s)
- Rikki K Quinn
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Hannah R Drury
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Ethan T Cresswell
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Melissa A Tadros
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Bryony A Nayagam
- Department of Audiology and Speech Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
| | - Rebecca Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia.,Hunter Medical Research Institute, The University of Newcastle, New Lambton Heights, NSW, Australia
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20
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Kalluri R. Similarities in the Biophysical Properties of Spiral-Ganglion and Vestibular-Ganglion Neurons in Neonatal Rats. Front Neurosci 2021; 15:710275. [PMID: 34712112 PMCID: PMC8546178 DOI: 10.3389/fnins.2021.710275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 09/07/2021] [Indexed: 11/13/2022] Open
Abstract
The membranes of auditory and vestibular afferent neurons each contain diverse groups of ion channels that lead to heterogeneity in their intrinsic biophysical properties. Pioneering work in both auditory- and vestibular-ganglion physiology have individually examined this remarkable diversity, but there are few direct comparisons between the two ganglia. Here the firing patterns recorded by whole-cell patch-clamping in neonatal vestibular- and spiral ganglion neurons are compared. Indicative of an overall heterogeneity in ion channel composition, both ganglia exhibit qualitatively similar firing patterns ranging from sustained-spiking to transient-spiking in response to current injection. The range of resting potentials, voltage thresholds, current thresholds, input-resistances, and first-spike latencies are similarly broad in both ganglion groups. The covariance between several biophysical properties (e.g., resting potential to voltage threshold and their dependence on postnatal age) was similar between the two ganglia. Cell sizes were on average larger and more variable in VGN than in SGN. One sub-group of VGN stood out as having extra-large somata with transient-firing patterns, very low-input resistance, fast first-spike latencies, and required large current amplitudes to induce spiking. Despite these differences, the input resistance per unit area of the large-bodied transient neurons was like that of smaller-bodied transient-firing neurons in both VGN and SGN, thus appearing to be size-scaled versions of other transient-firing neurons. Our analysis reveals that although auditory and vestibular afferents serve very different functions in distinct sensory modalities, their biophysical properties are more closely related by firing pattern and cell size than by sensory modality.
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Affiliation(s)
- Radha Kalluri
- Caruso Department of Otolaryngology-Head and Neck Surgery, Zilkha Neurogenetics Institute, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
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21
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Meredith FL, Rennie KJ. Dopaminergic Inhibition of Na + Currents in Vestibular Inner Ear Afferents. Front Neurosci 2021; 15:710321. [PMID: 34580582 PMCID: PMC8463658 DOI: 10.3389/fnins.2021.710321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 08/10/2021] [Indexed: 11/13/2022] Open
Abstract
Inner ear hair cells form synapses with afferent terminals and afferent neurons carry signals as action potentials to the central nervous system. Efferent neurons have their origins in the brainstem and some make synaptic contact with afferent dendrites beneath hair cells. Several neurotransmitters have been identified that may be released from efferent terminals to modulate afferent activity. Dopamine is a candidate efferent neurotransmitter in both the vestibular and auditory systems. Within the cochlea, activation of dopamine receptors may reduce excitotoxicity at the inner hair cell synapse via a direct effect of dopamine on afferent terminals. Here we investigated the effect of dopamine on sodium currents in acutely dissociated vestibular afferent calyces to determine if dopaminergic signaling could also modulate vestibular responses. Calyx terminals were isolated along with their accompanying type I hair cells from the cristae of gerbils (P15-33) and whole cell patch clamp recordings performed. Large transient sodium currents were present in all isolated calyces; compared to data from crista slices, resurgent Na+ currents were rare. Perfusion of dopamine (100 μM) in the extracellular solution significantly reduced peak transient Na+ currents by approximately 20% of control. A decrease in Na+ current amplitude was also seen with extracellular application of the D2 dopamine receptor agonist quinpirole, whereas the D2 receptor antagonist eticlopride largely abolished the response to dopamine. Inclusion of the phosphatase inhibitor okadaic acid in the patch electrode solution occluded the response to dopamine. The reduction in calyx sodium current in response to dopamine suggests efferent signaling through D2 dopaminergic receptors may occur via common mechanisms to decrease excitability in inner ear afferents.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology - Head & Neck Surgery, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Katherine J Rennie
- Department of Otolaryngology - Head & Neck Surgery, School of Medicine, University of Colorado, Aurora, CO, United States.,Department of Physiology & Biophysics, School of Medicine, University of Colorado, Aurora, CO, United States
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22
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Maroto AF, Barrallo-Gimeno A, Llorens J. Relationship between vestibular hair cell loss and deficits in two anti-gravity reflexes in the rat. Hear Res 2021; 410:108336. [PMID: 34481267 DOI: 10.1016/j.heares.2021.108336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 11/25/2022]
Abstract
The tail-lift reflex and the air-righting reflex in rats are anti-gravity reflexes that depend on vestibular function. To begin identifying their cellular basis, this study examined the relationship between reflex loss and the graded lesions caused in the vestibular sensory epithelia by varying doses of an ototoxic compound. After ototoxic exposure, we recorded these reflexes using high speed video. The movies were used to obtain objective measures of the reflexes: the minimum angle formed by the nose, the back of the neck and the base of the tail during the tail-lift maneuver and the time to right in the air-righting test. The vestibular sensory epithelia were then collected from the rats and used to estimate the loss of type I (HCI), type II (HCII) and all hair cells (HC) in both central and peripheral parts of the crista, utricle, and saccule. As expected, tail-lift angles decreased, and air-righting times increased, while the numbers of HCs remaining in the epithelia decreased in a dose-dependent manner. The results demonstrated greater sensitivity of HCI compared to HCII to the IDPN ototoxicity, as well as a relative resiliency of the saccule compared to the crista and utricle. Comparing the functional measures with the cell counts, we observed that loss of the tail-lift reflex associates better with HCI than with HCII loss. In contrast, most HCI in the crista and utricle were lost before air-righting times increased. These data suggest that these reflexes depend on the function of non-identical populations of vestibular HCs.
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Affiliation(s)
- Alberto F Maroto
- Departament de Ciències Fisiològiques, Institut de Neurociènces, Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalunya, Spain.
| | - Alejandro Barrallo-Gimeno
- Departament de Ciències Fisiològiques, Institut de Neurociènces, Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalunya, Spain; Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, 08907 L'Hospitalet de Llobregat, Catalunya, Spain.
| | - Jordi Llorens
- Departament de Ciències Fisiològiques, Institut de Neurociènces, Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalunya, Spain; Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, 08907 L'Hospitalet de Llobregat, Catalunya, Spain.
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23
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Curthoys IS, Grant JW, Pastras CJ, Fröhlich L, Brown DJ. Similarities and Differences Between Vestibular and Cochlear Systems - A Review of Clinical and Physiological Evidence. Front Neurosci 2021; 15:695179. [PMID: 34456671 PMCID: PMC8397526 DOI: 10.3389/fnins.2021.695179] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/12/2021] [Indexed: 12/04/2022] Open
Abstract
The evoked response to repeated brief stimuli, such as clicks or short tone bursts, is used for clinical evaluation of the function of both the auditory and vestibular systems. One auditory response is a neural potential - the Auditory Brainstem Response (ABR) - recorded by surface electrodes on the head. The clinical analogue for testing the otolithic response to abrupt sounds and vibration is the myogenic potential recorded from tensed muscles - the vestibular evoked myogenic potential (VEMP). VEMPs have provided clinicians with a long sought-after tool - a simple, clinically realistic indicator of the function of each of the 4 otolithic sensory regions. We review the basic neural evidence for VEMPs and discuss the similarities and differences between otolithic and cochlear receptors and afferents. VEMPs are probably initiated by sound or vibration selectively activating afferent neurons with irregular resting discharge originating from the unique type I receptors at a specialized region of the otolithic maculae (the striola). We review how changes in VEMP responses indicate the functional state of peripheral vestibular function and the likely transduction mechanisms allowing otolithic receptors and afferents to trigger such very short latency responses. In section "ELECTROPHYSIOLOGY" we show how cochlear and vestibular receptors and afferents have many similar electrophysiological characteristics [e.g., both generate microphonics, summating potentials, and compound action potentials (the vestibular evoked potential, VsEP)]. Recent electrophysiological evidence shows that the hydrodynamic changes in the labyrinth caused by increased fluid volume (endolymphatic hydrops), change the responses of utricular receptors and afferents in a way which mimics the changes in vestibular function attributed to endolymphatic hydrops in human patients. In section "MECHANICS OF OTOLITHS IN VEMPS TESTING" we show how the major VEMP results (latency and frequency response) follow from modeling the physical characteristics of the macula (dimensions, stiffness etc.). In particular, the structure and mechanical operation of the utricular macula explains the very fast response of the type I receptors and irregular afferents which is the very basis of VEMPs and these structural changes of the macula in Menière's Disease (MD) predict the upward shift of VEMP tuning in these patients.
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Affiliation(s)
- Ian S. Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia
| | - John Wally Grant
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, United States
| | - Christopher J. Pastras
- The Menière’s Research Laboratory, Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
| | - Laura Fröhlich
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Daniel J. Brown
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA, Australia
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24
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Reichenberger I, Caussidier-Dechesne CJ, Straka H. Calretinin Immunoreactivity in the VIIIth Nerve and Inner Ear Endorgans of Ranid Frogs. Front Neurosci 2021; 15:691962. [PMID: 34305520 PMCID: PMC8292642 DOI: 10.3389/fnins.2021.691962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/16/2021] [Indexed: 11/13/2022] Open
Abstract
Calcium-binding proteins are essential for buffering intracellular calcium concentrations, which are critical for regulating cellular processes involved in neuronal computations. One such calcium-binding protein, calretinin, is present in many neurons of the central nervous system as well as those which innervate cranial sensory organs, although often with differential distributions in adjacent cellular elements. Here, we determined the presence and distribution of calretinin-immunoreactivity in the peripheral vestibular and auditory system of ranid frogs. Calretinin-immunoreactivity was observed in ganglion cells innervating the basilar and amphibian papilla, and in a subpopulation of ganglion cells innervating the saccular epithelium. In contrast, none of the ganglion cells innervating the lagena, the utricle, or the three semicircular canals were calretinin-immunopositive, suggesting that this calcium-binding protein is a marker for auditory but not vestibular afferent fibers in the frog. The absence of calretinin in vestibular ganglion cells corresponds with the lack of type I hair cells in anamniote vertebrates, many of which in amniotes are contacted by the neurites of large, calyx-forming calretinin-immunopositive ganglion cells. In the sensory epithelia of all endorgans, the majority of hair cells were strongly calretinin-immunopositive. Weakly calretinin-immunopositive hair cells were distributed in the intermediate region of the semicircular canal cristae, the central part of the saccular macula, the utricular, and lagenar striola and the medial part of the amphibian papilla. The differential presence of calretinin in the frog vestibular and auditory sensory periphery might reflect a biochemical feature related to firing patterns and frequency bandwidths of self-motion versus acoustic stimulus encoding, respectively.
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Affiliation(s)
| | | | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, Planegg, Germany
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25
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Rutherford MA, von Gersdorff H, Goutman JD. Encoding sound in the cochlea: from receptor potential to afferent discharge. J Physiol 2021; 599:2527-2557. [PMID: 33644871 PMCID: PMC8127127 DOI: 10.1113/jp279189] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/22/2021] [Indexed: 12/17/2022] Open
Abstract
Ribbon-class synapses in the ear achieve analog to digital transformation of a continuously graded membrane potential to all-or-none spikes. In mammals, several auditory nerve fibres (ANFs) carry information from each inner hair cell (IHC) to the brain in parallel. Heterogeneity of transmission among synapses contributes to the diversity of ANF sound-response properties. In addition to the place code for sound frequency and the rate code for sound level, there is also a temporal code. In series with cochlear amplification and frequency tuning, neural representation of temporal cues over a broad range of sound levels enables auditory comprehension in noisy multi-speaker settings. The IHC membrane time constant introduces a low-pass filter that attenuates fluctuations of the receptor potential above 1-2 kHz. The ANF spike generator adds a high-pass filter via its depolarization-rate threshold that rejects slow changes in the postsynaptic potential and its phasic response property that ensures one spike per depolarization. Synaptic transmission involves several stochastic subcellular processes between IHC depolarization and ANF spike generation, introducing delay and jitter that limits the speed and precision of spike timing. ANFs spike at a preferred phase of periodic sounds in a process called phase-locking that is limited to frequencies below a few kilohertz by both the IHC receptor potential and the jitter in synaptic transmission. During phase-locking to periodic sounds of increasing intensity, faster and facilitated activation of synaptic transmission and spike generation may be offset by presynaptic depletion of synaptic vesicles, resulting in relatively small changes in response phase. Here we review encoding of spike-timing at cochlear ribbon synapses.
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Affiliation(s)
- Mark A. Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Henrique von Gersdorff
- Vollum Institute, Oregon Hearing Research Center, Oregon Health and Sciences University, Portland, Oregon 97239
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26
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Phase-Locking Requires Efficient Ca 2+ Extrusion at the Auditory Hair Cell Ribbon Synapse. J Neurosci 2021; 41:1625-1635. [PMID: 33446517 DOI: 10.1523/jneurosci.1324-18.2020] [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: 05/17/2018] [Revised: 08/25/2020] [Accepted: 12/27/2020] [Indexed: 11/21/2022] Open
Abstract
Proper perception of sounds in the environment requires auditory signals to be encoded with extraordinary temporal precision up to tens of microseconds, but how it originates from the hearing organs in the periphery is poorly understood. In particular, sound-evoked spikes in auditory afferent fibers in vivo are phase-locked to sound frequencies up to 5 kHz, but it is not clear how hair cells can handle intracellular Ca2+ changes with such high speed and efficiency. In this study, we combined patch-clamp recording and two-photon Ca2+ imaging to examine Ca2+ dynamics in hair cell ribbon synapses in the bullfrog amphibian papilla of both sexes. We found that Ca2+ clearance from single synaptic ribbons followed a double exponential function, and the weight of the fast component, but not the two time constants, was significantly reduced for prolonged stimulation, and during inhibition of the plasma membrane Ca2+ ATPase (PMCA), the mitochondrial Ca2+ uptake (MCU), or the sarcolemma/endoplasmic reticulum Ca2+ ATPase (SERCA), but not the Na+/Ca2+ exchanger (NCX). Furthermore, we found that both the basal Ca2+ level and the Ca2+ rise during sinusoidal stimulation were significantly increased by inhibition of PMCA, MCU, or SERCA. Consistently, phase-locking of synaptic vesicle releases from hair cells was also significantly reduced by blocking PMCA, MCU, or SERCA, but not NCX. We conclude that, in addition to fast diffusion mediated by mobile Ca2+ buffer, multiple Ca2+ extrusion pumps are required for phase-locking at the auditory hair cell ribbon synapse.SIGNIFICANCE STATEMENT Hair cell synapses can transmit sound-driven signals precisely in the kHz range. However, previous studies of Ca2+ handling in auditory hair cells have often been conducted in immature hair cells, with elevated extracellular Ca2+ concentration, or through steady-state stimulation that may not be physiologically relevant. Here we examine Ca2+ clearance from hair cell synaptic ribbons in a fully mature preparation at physiological concentration of external Ca2+ and at physiological temperature. By stimulating hair cells with sinusoidal voltage commands that mimic pure sound tones, we recapitulated the phase-locking of hair cell exocytosis with an in vitro approach. This allowed us to reveal the Ca2+ extrusion mechanisms that are required for phase-locking at auditory hair cell ribbon synapses.
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27
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Ramakrishna Y, Manca M, Glowatzki E, Sadeghi SG. Cholinergic Modulation of Membrane Properties of Calyx Terminals in the Vestibular Periphery. Neuroscience 2020; 452:98-110. [PMID: 33197502 DOI: 10.1016/j.neuroscience.2020.10.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 01/10/2023]
Abstract
Vestibular nerve afferents are divided into regular and irregular groups based on the variability of interspike intervals in their resting discharge. Most afferents receive inputs from bouton terminals that contact type II hair cells as well as from calyx terminals that cover the basolateral walls of type I hair cells. Calyces have an abundance of different subtypes of KCNQ (Kv7) potassium channels and muscarinic acetylcholine receptors (mAChRs) and receive cholinergic efferent inputs from neurons in the brainstem. We investigated whether mAChRs affected membrane properties and firing patterns of calyx terminals through modulation of KCNQ channel activity. Patch clamp recordings were performed from calyx terminals in central regions of the cristae of the horizontal and anterior canals in 13-26 day old Sprague-Dawley rats. KCNQ mediated currents were observed as voltage sensitive currents with slow kinetics (activation and deactivation), resulting in spike frequency adaptation so that calyces at best fired a single action potential at the beginning of a depolarizing step. Activation of mAChRs by application of oxotremorine methiodide or inhibition of KCNQ channels by linopirdine dihydrochloride decreased voltage activated currents by ∼30%, decreased first spike latencies by ∼40%, resulted in action potential generation in response to smaller current injections and at lower (i.e., more hyperpolarized) membrane potentials, and increased the number of spikes fired during depolarizing steps. Interestingly, some of the calyces showed spontaneous discharge in the presence of these drugs. Together, these findings suggest that cholinergic efferents can modulate the response properties and encoding of head movements by afferents.
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Affiliation(s)
- Yugandhar Ramakrishna
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, NY, United States; Department of Communication Disorders and Sciences, California State University, Northridge, CA, United States
| | - Marco Manca
- Department of Otolaryngology - Head and Neck Surgery, The Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Elisabeth Glowatzki
- Department of Otolaryngology - Head and Neck Surgery, The Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Soroush G Sadeghi
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, NY, United States; Neuroscience Program, State University of New York at Buffalo, Buffalo, NY, United States.
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28
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Barozzi S, Soi D, Intieri E, Giani M, Aldè M, Tonon E, Signorini L, Renieri A, Fallerini C, Perin P, Montini G, Ambrosetti U. Vestibular and audiological findings in the Alport syndrome. Am J Med Genet A 2020; 182:2345-2358. [PMID: 32820599 DOI: 10.1002/ajmg.a.61796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/28/2020] [Accepted: 06/29/2020] [Indexed: 01/20/2023]
Abstract
Alport syndrome (AS) is caused by mutations in collagen IV, which is widespread in the basement membranes of many organs, including the kidneys, eyes, and ears. Whereas the effects of collagen IV changes in the cochlea are well known, no changes have been described in the posterior labyrinth. The aim of this study was to investigate both the auditory and the vestibular function of a group of individuals with AS. Seventeen patients, aged 9-52, underwent audiological tests including pure-tone and speech audiometry, immittance test and otoacoustic emissions and vestibular tests including video head impulse test, rotatory test, and vestibular evoked myogenic potentials. Hearing loss affected 25% of the males and 27.3% of the females with X-linked AS. It was sensorineural with a cochlear localization and a variable severity. 50% of the males and 45.4% of the females had a hearing impairment in the high-frequency range. Otoacoustic emissions were absent in about one-third of the individuals. A peripheral vestibular dysfunction was present in 75% of the males and 45.4% of the females, with no complaints of vertigo or dizziness. The vestibular impairment was compensated and the vestibulo-ocular reflex asymmetry was more evident in rotatory tests carried out at lower than higher speeds; a vestibular hypofunction was present in all hearing impaired ears although it was also found in subjects with normal hearing. A posterior labyrinth injury should be hypothesized in AS even when the patient does not manifest hearing disorders or evident signs of renal failure.
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Affiliation(s)
- Stefania Barozzi
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Daniela Soi
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,ASST Nord Milano, Milan, Italy
| | - Elisabetta Intieri
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,UOC Otorinolaringoiatria ASST Valle Olona, Busto Arsizio, Italy
| | - Marisa Giani
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Mirko Aldè
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,UOC Audiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Eleonora Tonon
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Lia Signorini
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Paola Perin
- Dipartimento di scienze del Sistema nervoso e del comportamento, Università di Pavia, Pavia, Italy
| | - Giovanni Montini
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Giuliana Bernardo Caprotti chair of Pediatrics, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Umberto Ambrosetti
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,UOC Audiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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29
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Ramakrishna Y, Sadeghi SG. Activation of GABA B receptors results in excitatory modulation of calyx terminals in rat semicircular canal cristae. J Neurophysiol 2020; 124:962-972. [PMID: 32816581 PMCID: PMC7509296 DOI: 10.1152/jn.00243.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/15/2022] Open
Abstract
Previous studies have found GABA in vestibular end organs. However, existence of GABA receptors or possible GABAergic effects on vestibular nerve afferents has not been investigated. The current study was conducted to determine whether activation of GABAB receptors affects calyx afferent terminals in the central region of the cristae of semicircular canals. We used patch-clamp recording in postnatal day 13-18 (P13-P18) Sprague-Dawley rats of either sex. Application of GABAB receptor agonist baclofen inhibited voltage-sensitive potassium currents. This effect was blocked by selective GABAB receptor antagonist CGP 35348. Application of antagonists of small (SK)- and large-conductance potassium (BK) channels almost completely blocked the effects of baclofen. The remaining baclofen effect was blocked by cadmium chloride, suggesting that it could be due to inhibition of voltage-gated calcium channels. Furthermore, baclofen had no effect in the absence of calcium in the extracellular fluid. Inhibition of potassium currents by GABAB activation resulted in an excitatory effect on calyx terminal action potential firing. While in the control condition calyces could only fire a single action potential during step depolarizations, in the presence of baclofen they fired continuously during steps and a few even showed repetitive discharge. We also found a decrease in threshold for action potential generation and a decrease in first-spike latency during step depolarization. These results provide the first evidence for the presence of GABAB receptors on calyx terminals, showing that their activation results in an excitatory effect and that GABA inputs could be used to modulate calyx response properties.NEW & NOTEWORTHY Using in vitro whole cell patch-clamp recordings from calyx terminals in the vestibular end organs, we show that activation of GABAB receptors result in an excitatory effect, with decreased spike-frequency adaptation and shortened first-spike latencies. Our results suggest that these effects are mediated through inhibition of calcium-sensitive potassium channels.
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Affiliation(s)
- Yugandhar Ramakrishna
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, New York
- Department of Communication Disorders and Sciences, California State University, Northridge, Northridge, California
| | - Soroush G Sadeghi
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, New York
- Neuroscience Program, State University of New York at Buffalo, Buffalo, New York
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30
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Meredith FL, Rennie KJ. Persistent and resurgent Na + currents in vestibular calyx afferents. J Neurophysiol 2020; 124:510-524. [PMID: 32667253 DOI: 10.1152/jn.00124.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Vestibular afferent neurons convey information from hair cells in the peripheral vestibular end organs to central nuclei. Primary vestibular afferent neurons can fire action potentials at high rates and afferent firing patterns vary with the position of nerve terminal endings in vestibular neuroepithelia. Terminals contact hair cells as small bouton or large calyx endings. To investigate the role of Na+ currents (INa) in firing mechanisms, we investigated biophysical properties of INa in calyx-bearing afferents. Whole cell patch-clamp recordings were made from calyx terminals in thin slices of gerbil crista at different postnatal ages: immature [postnatal day (P)5-P8, young (P13-P15), and mature (P30-P45)]. A large transient Na+ current (INaT) was completely blocked by 300 nM tetrodotoxin (TTX) in mature calyces. In addition, INaT was accompanied by much smaller persistent Na+ currents (INaP) and distinctive resurgent Na+ currents (INaR), which were also blocked by TTX. ATX-II, a toxin that slows Na+ channel inactivation, enhanced INaP in immature and mature calyces. 4,9-Anhydro-TTX (4,9-ah-TTX), which selectively blocks Nav1.6 channels, abolished the enhanced INa in mature, but not immature, calyces. Therefore, Nav1.6 channels mediate a component of INaT and INaP in mature calyces, but are minimally expressed at early postnatal days. INaR was expressed in less than one-third of calyces at P6-P8, but expression increased with development, and in mature cristae INaR was frequently found in peripheral calyces. INaR served to increase the availability of Na+ channels following brief membrane depolarizations. In current clamp, the rate and regularity of action potential firing decreased in mature peripheral calyces following 4,9-ah-TTX application. Therefore, Nav1.6 channels are upregulated during development, contribute to INaT, INaP, and INaR, and may regulate excitability by enabling higher mean discharge rates in a subpopulation of mature calyx afferents.NEW & NOTEWORTHY Action potential firing patterns differ between groups of afferent neurons innervating vestibular epithelia. We investigated the biophysical properties of Na+ currents in specialized vestibular calyx afferent terminals during postnatal development. Mature calyces express Na+ currents with transient, persistent, and resurgent components. Nav1.6 channels contribute to resurgent Na+ currents and may enhance firing in peripheral calyx afferents. Understanding Na+ channels that contribute to vestibular nerve responses has implications for developing new treatments for vestibular dysfunction.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado
| | - Katherine J Rennie
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado.,Department of Physiology & Biophysics, University of Colorado School of Medicine, Aurora, Colorado
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31
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Spaiardi P, Tavazzani E, Manca M, Russo G, Prigioni I, Biella G, Giunta R, Johnson SL, Marcotti W, Masetto S. K + Accumulation and Clearance in the Calyx Synaptic Cleft of Type I Mouse Vestibular Hair Cells. Neuroscience 2020; 426:69-86. [PMID: 31846752 PMCID: PMC6985899 DOI: 10.1016/j.neuroscience.2019.11.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 11/07/2019] [Accepted: 11/16/2019] [Indexed: 11/29/2022]
Abstract
Vestibular organs of Amniotes contain two types of sensory cells, named Type I and Type II hair cells. While Type II hair cells are contacted by several small bouton nerve terminals, Type I hair cells receive a giant terminal, called a calyx, which encloses their basolateral membrane almost completely. Both hair cell types release glutamate, which depolarizes the afferent terminal by binding to AMPA post-synaptic receptors. However, there is evidence that non-vesicular signal transmission also occurs at the Type I hair cell-calyx synapse, possibly involving direct depolarization of the calyx by K+ exiting the hair cell. To better investigate this aspect, we performed whole-cell patch-clamp recordings from mouse Type I hair cells or their associated calyx. We found that [K+] in the calyceal synaptic cleft is elevated at rest relative to the interstitial (extracellular) solution and can increase or decrease during hair cell depolarization or repolarization, respectively. The change in [K+] was primarily driven by GK,L, the low-voltage-activated, non-inactivating K+ conductance specifically expressed by Type I hair cells. Simple diffusion of K+ between the cleft and the extracellular compartment appeared substantially restricted by the calyx inner membrane, with the ion channels and active transporters playing a crucial role in regulating intercellular [K+]. Calyx recordings were consistent with K+ leaving the synaptic cleft through postsynaptic voltage-gated K+ channels involving KV1 and KV7 subunits. The above scenario is consistent with direct depolarization and hyperpolarization of the calyx membrane potential by intercellular K+.
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Affiliation(s)
- P Spaiardi
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - E Tavazzani
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - M Manca
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - G Russo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - I Prigioni
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - G Biella
- Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - R Giunta
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy
| | - S L Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - W Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - S Masetto
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia 27100, Italy.
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32
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Ono K, Keller J, López Ramírez O, González Garrido A, Zobeiri OA, Chang HHV, Vijayakumar S, Ayiotis A, Duester G, Della Santina CC, Jones SM, Cullen KE, Eatock RA, Wu DK. Retinoic acid degradation shapes zonal development of vestibular organs and sensitivity to transient linear accelerations. Nat Commun 2020; 11:63. [PMID: 31896743 PMCID: PMC6940366 DOI: 10.1038/s41467-019-13710-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 11/21/2019] [Indexed: 01/18/2023] Open
Abstract
Each vestibular sensory epithelium in the inner ear is divided morphologically and physiologically into two zones, called the striola and extrastriola in otolith organ maculae, and the central and peripheral zones in semicircular canal cristae. We found that formation of striolar/central zones during embryogenesis requires Cytochrome P450 26b1 (Cyp26b1)-mediated degradation of retinoic acid (RA). In Cyp26b1 conditional knockout mice, formation of striolar/central zones is compromised, such that they resemble extrastriolar/peripheral zones in multiple features. Mutants have deficient vestibular evoked potential (VsEP) responses to jerk stimuli, head tremor and deficits in balance beam tests that are consistent with abnormal vestibular input, but normal vestibulo-ocular reflexes and apparently normal motor performance during swimming. Thus, degradation of RA during embryogenesis is required for formation of highly specialized regions of the vestibular sensory epithelia with specific functions in detecting head motions.
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Affiliation(s)
- Kazuya Ono
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
| | - James Keller
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
- Qiagen Sciences Inc., Germantown, MD, 20874, USA
| | - Omar López Ramírez
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | | | - Omid A Zobeiri
- Department of Physiology McGill University, Montreal, QC, Canada, H3G 1Y6
| | | | - Sarath Vijayakumar
- Department of Special Education and Communication Disorders, 301 Barkley Memorial Center, University of Nebraska-Lincoln, Lincoln, NE, 68583-0738, USA
| | - Andrianna Ayiotis
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Gregg Duester
- Neuroscience and Aging Research Center, Stanford Burnham Prebys Medical Discovery Institutes, Stanford, CA, 92037, USA
| | - Charles C Della Santina
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, 301 Barkley Memorial Center, University of Nebraska-Lincoln, Lincoln, NE, 68583-0738, USA
| | - Kathleen E Cullen
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Ruth Anne Eatock
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | - Doris K Wu
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA.
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33
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Affiliation(s)
- Henrique von Gersdorff
- Vollum Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA.,Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA.,Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Marta M Iversen
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Richard D Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, 84112, USA.,Department of Otolaryngology, University of Utah, Salt Lake City, Utah, 84112, USA
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34
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Poppi LA, Holt JC, Lim R, Brichta AM. A review of efferent cholinergic synaptic transmission in the vestibular periphery and its functional implications. J Neurophysiol 2019; 123:608-629. [PMID: 31800345 DOI: 10.1152/jn.00053.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been over 60 years since peripheral efferent vestibular terminals were first identified in mammals, and yet the function of the efferent vestibular system remains obscure. One reason for the lack of progress may be due to our deficient understanding of the peripheral efferent synapse. Although vestibular efferent terminals were identified as cholinergic less than a decade after their anatomical characterization, the cellular mechanisms that underlie the properties of these synapses have had to be inferred. In this review we examine how recent mammalian studies have begun to reveal both nicotinic and muscarinic effects at these terminals and therefore provide a context for fast and slow responses observed in classic electrophysiological studies of the mammalian efferent vestibular system, nearly 40 years ago. Although incomplete, these new results together with those of recent behavioral studies are helping to unravel the mysterious and perplexing action of the efferent vestibular system. Armed with this information, we may finally appreciate the behavioral framework in which the efferent vestibular system operates.
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Affiliation(s)
- L A Poppi
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
| | - J C Holt
- Department of Otolaryngology, University of Rochester Medical Center, Rochester, New York
| | - R Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
| | - A M Brichta
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
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35
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Contini D, Holstein GR, Art JJ. Synaptic cleft microenvironment influences potassium permeation and synaptic transmission in hair cells surrounded by calyx afferents in the turtle. J Physiol 2019; 598:853-889. [PMID: 31623011 DOI: 10.1113/jp278680] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/13/2019] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS In central regions of vestibular semicircular canal epithelia, the [K+ ] in the synaptic cleft ([K+ ]c ) contributes to setting the hair cell and afferent membrane potentials; the potassium efflux from type I hair cells results from the interdependent gating of three conductances. Elevation of [K+ ]c occurs through a calcium-activated potassium conductance, GBK , and a low-voltage-activating delayed rectifier, GK(LV) , that activates upon elevation of [K+ ]c . Calcium influx that enables quantal transmission also activates IBK , an effect that can be blocked internally by BAPTA, and externally by a CaV 1.3 antagonist or iberiotoxin. Elevation of [K+ ]c or chelation of [Ca2+ ]c linearizes the GK(LV) steady-state I-V curve, suggesting that the outward rectification observed for GK(LV) may result largely from a potassium-sensitive relief of Ca2+ inactivation of the channel pore selectivity filter. Potassium sensitivity of hair cell and afferent conductances allows three modes of transmission: quantal, ion accumulation and resistive coupling to be multiplexed across the synapse. ABSTRACT In the vertebrate nervous system, ions accumulate in diffusion-limited synaptic clefts during ongoing activity. Such accumulation can be demonstrated at large appositions such as the hair cell-calyx afferent synapses present in central regions of the turtle vestibular semicircular canal epithelia. Type I hair cells influence discharge rates in their calyx afferents by modulating the potassium concentration in the synaptic cleft, [K+ ]c , which regulates potassium-sensitive conductances in both hair cell and afferent. Dual recordings from synaptic pairs have demonstrated that, despite a decreased driving force due to potassium accumulation, hair cell depolarization elicits sustained outward currents in the hair cell, and a maintained inward current in the afferent. We used kinetic and pharmacological dissection of the hair cell conductances to understand the interdependence of channel gating and permeation in the context of such restricted extracellular spaces. Hair cell depolarization leads to calcium influx and activation of a large calcium-activated potassium conductance, GBK , that can be blocked by agents that disrupt calcium influx or buffer the elevation of [Ca2+ ]i , as well as by the specific KCa 1.1 blocker iberiotoxin. Efflux of K+ through GBK can rapidly elevate [K+ ]c , which speeds the activation and slows the inactivation and deactivation of a second potassium conductance, GK(LV) . Elevation of [K+ ]c or chelation of [Ca2+ ]c linearizes the GK(LV) steady-state I-V curve, consistent with a K+ -dependent relief of Ca2+ inactivation of GK(LV) . As a result, this potassium-sensitive hair cell conductance pairs with the potassium-sensitive hyperpolarization-activated cyclic nucleotide-gated channel (HCN) conductance in the afferent and creates resistive coupling at the synaptic cleft.
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Affiliation(s)
- Donatella Contini
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, 808 S. Wood St, Chicago, IL, 60612, USA
| | - Gay R Holstein
- Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Ave, New York, NY, 10029, USA
| | - Jonathan J Art
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, 808 S. Wood St, Chicago, IL, 60612, USA
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36
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Efferent Inputs Are Required for Normal Function of Vestibular Nerve Afferents. J Neurosci 2019; 39:6922-6935. [PMID: 31285300 DOI: 10.1523/jneurosci.0237-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 01/09/2023] Open
Abstract
A group of vestibular afferent nerve fibers with irregular-firing resting discharges are thought to play a prominent role in responses to fast head movements and vestibular plasticity. We show that, in C57BL/6 mice (either sex, 4-5 weeks old), normal activity in the efferent vestibular pathway is required for function of these irregular afferents. Thermal inhibition of efferent fibers results in a profound inhibition of irregular afferents' resting discharges, rendering them inadequate for signaling head movements. In this way, efferent inputs adjust the contribution of the peripheral irregular afferent pathway that plays a critical role in peripheral vestibular signaling and plasticity.SIGNIFICANCE STATEMENT Vestibular end organs in the inner ear receive efferent inputs from the brainstem. Previously, electrical stimulation of efferents was linked to an increase in resting discharges of afferents and a decrease in their sensitivities. Here, we show that localized thermal inhibition of unmyelinated efferents results in a significant decrease in the activity of afferent nerve fibers, particularly those with irregular resting discharges implicated in responses to fast head movements and vestibular compensation. Thus, by upregulating and downregulating of afferent firing, particularly irregular afferents, efferents adjust neural activity sensitive to rapid head movements. These findings support the notion that peripheral vestibular end organs are not passive transducers of head movements and their sensory signal transmission is modulated by efferent inputs.
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37
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Dembla M, Kesharwani A, Natarajan S, Fecher-Trost C, Fairless R, Williams SK, Flockerzi V, Diem R, Schwarz K, Schmitz F. Early auto-immune targeting of photoreceptor ribbon synapses in mouse models of multiple sclerosis. EMBO Mol Med 2019; 10:emmm.201808926. [PMID: 30266776 PMCID: PMC6220320 DOI: 10.15252/emmm.201808926] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Optic neuritis is one of the first manifestations of multiple sclerosis. Its pathogenesis is incompletely understood, but considered to be initiated by an auto‐immune response directed against myelin sheaths of the optic nerve. Here, we demonstrate in two frequently used and well‐validated mouse models of optic neuritis that ribbon synapses in the myelin‐free retina are targeted by an auto‐reactive immune system even before alterations in the optic nerve have developed. The auto‐immune response is directed against two adhesion proteins (CASPR1/CNTN1) that are present both in the paranodal region of myelinated nerves as well as at retinal ribbon synapses. This occurs in parallel with altered synaptic vesicle cycling in retinal ribbon synapses and altered visual behavior before the onset of optic nerve demyelination. These findings indicate that early synaptic dysfunctions in the retina contribute to the pathology of optic neuritis in multiple sclerosis.
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Affiliation(s)
- Mayur Dembla
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, Homburg, Germany
| | - Ajay Kesharwani
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, Homburg, Germany
| | - Sivaraman Natarajan
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, Homburg, Germany
| | - Claudia Fecher-Trost
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical School, Saarland University, Homburg, Germany
| | - Richard Fairless
- Department of Neurology, University Clinic Heidelberg, Heidelberg, Germany
| | - Sarah K Williams
- Department of Neurology, University Clinic Heidelberg, Heidelberg, Germany
| | - Veit Flockerzi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical School, Saarland University, Homburg, Germany
| | - Ricarda Diem
- Department of Neurology, University Clinic Heidelberg, Heidelberg, Germany
| | - Karin Schwarz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, Homburg, Germany
| | - Frank Schmitz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, Homburg, Germany
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38
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Holman HA, Poppi LA, Frerck M, Rabbitt RD. Spontaneous and Acetylcholine Evoked Calcium Transients in the Developing Mouse Utricle. Front Cell Neurosci 2019; 13:186. [PMID: 31133810 PMCID: PMC6514437 DOI: 10.3389/fncel.2019.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/12/2019] [Indexed: 11/13/2022] Open
Abstract
Spontaneous calcium transients are present during early postnatal development in the mouse retina and cochlea, and play an important role in maturation of the sensory organs and neural circuits in the central nervous system (CNS). It is not known whether similar calcium transients occur during postnatal development in the vestibular sensory organs. Here we demonstrate spontaneous intracellular calcium transients in sensory hair cells (HCs) and supporting cells (SCs) in the murine utricular macula during the first two postnatal weeks. Calcium transients were monitored using a genetically encoded calcium indicator, GCaMP5G (G5), at 100 ms-frame−1 in excised utricle sensory epithelia, including HCs, SCs, and neurons. The reporter line expressed G5 and tdTomato (tdT) in a Gad2-Cre dependent manner within a subset of utricular HCs, SCs and neurons. Kinetics of the G5 reporter limited temporal resolution to calcium events lasting longer than 200 ms. Spontaneous calcium transients lasting 1-2 s were observed in the expressing population of HCs at birth and slower spontaneous transients lasting 10-30 s appeared in SCs by P3. Beginning at P5, calcium transients could be modulated by application of the efferent neurotransmitter acetylcholine (ACh). In mature mice, calcium transients in the utricular macula occurred spontaneously, had a duration 1-2 s, and could be modulated by the exogenous application of acetylcholine (ACh) or muscarine. Long-lasting calcium transients evoked by ACh in mature mice were blocked by atropine, consistent with previous reports describing the role of muscarinic receptors expressed in calyx bearing afferents in efferent control of vestibular sensation. Large spontaneous and ACh evoked transients were reversibly blocked by the inositol trisphosphate receptor (IP3R) antagonist aminoethoxydiphenyl borate (2-APB). Results demonstrate long-lasting calcium transients are present in the utricular macula during the first postnatal week, and that responses to ACh mature over this same time period.
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Affiliation(s)
- Holly A Holman
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Lauren A Poppi
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States.,School of Biomedical Science and Pharmacy, Hunter Medical Research Institute, University of Newcastle, Newcastle, NSW, Australia
| | - Micah Frerck
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Richard D Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States.,Neuroscience Program, University of Utah, Salt Lake City, UT, United States.,Otolaryngology-Head and Neck Surgery, University of Utah, Salt Lake City, UT, United States
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39
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Kwan A, Forbes PA, Mitchell DE, Blouin JS, Cullen KE. Neural substrates, dynamics and thresholds of galvanic vestibular stimulation in the behaving primate. Nat Commun 2019; 10:1904. [PMID: 31015434 PMCID: PMC6478681 DOI: 10.1038/s41467-019-09738-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/21/2019] [Indexed: 11/09/2022] Open
Abstract
Galvanic vestibular stimulation (GVS) uses the external application of electrical current to selectively target the vestibular system in humans. Despite its recent popularity for the assessment/treatment of clinical conditions, exactly how this non-invasive tool activates the vestibular system remains an open question. Here we directly investigate single vestibular afferent responses to GVS applied to the mastoid processes of awake-behaving monkeys. Transmastoid GVS produces robust and parallel activation of both canal and otolith afferents. Notably, afferent activation increases with intrinsic neuronal variability resulting in constant GVS-evoked neuronal detection thresholds across all afferents. Additionally, afferent tuning differs for GVS versus natural self-motion stimulation. Using a stochastic model of repetitive activity in afferents, we largely explain the main features of GVS-evoked vestibular afferent dynamics. Taken together, our results reveal the neural substrate underlying transmastoid GVS-evoked perceptual, ocular and postural responses-information that is essential to advance GVS applicability for biomedical uses in humans.
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Affiliation(s)
- Annie Kwan
- Department of Biomedical Engineering, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Patrick A Forbes
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, 3000 CA, The Netherlands.,Department of BioMechanical Engineering, Delft University of Technology, Delft, 2628 CD, The Netherlands.,School of Kinesiology, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Diana E Mitchell
- Department of Physiology, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, QC, H3G 1Y6, Canada. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, 21205, MD, USA.
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40
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Curthoys I, Burgess AM, Goonetilleke SC. Phase-locking of irregular guinea pig primary vestibular afferents to high frequency (>250 Hz) sound and vibration. Hear Res 2019; 373:59-70. [DOI: 10.1016/j.heares.2018.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/07/2018] [Accepted: 12/21/2018] [Indexed: 12/28/2022]
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41
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Eatock RA. Specializations for Fast Signaling in the Amniote Vestibular Inner Ear. Integr Comp Biol 2019; 58:341-350. [PMID: 29920589 DOI: 10.1093/icb/icy069] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
During rapid locomotion, the vestibular inner ear provides head-motion signals that stabilize posture, gaze, and heading. Afferent nerve fibers from central and peripheral zones of vestibular sensory epithelia use temporal and rate encoding, respectively, to emphasize different aspects of head motion: central afferents adapt faster to sustained head position and favor higher stimulus frequencies, reflecting specializations at each stage from motion of the accessory structure to spike propagation to the brain. One specialization in amniotes is an unusual nonquantal synaptic mechanism by which type I hair cells transmit to large calyceal terminals of afferent neurons. The reduced synaptic delay of this mechanism may have evolved to serve reliable and fast input to reflex pathways that ensure stable locomotion on land.
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Affiliation(s)
- Ruth Anne Eatock
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
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Enhanced Activation of HCN Channels Reduces Excitability and Spike-Timing Regularity in Maturing Vestibular Afferent Neurons. J Neurosci 2019; 39:2860-2876. [PMID: 30696730 DOI: 10.1523/jneurosci.1811-18.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 01/14/2019] [Accepted: 01/19/2019] [Indexed: 11/21/2022] Open
Abstract
Vestibular ganglion neurons (VGNs) transmit information along parallel neuronal pathways whose signature distinction is variability in spike-timing; some fire at regular intervals while others fire at irregular intervals. The mechanisms driving timing differences are not fully understood but two opposing (but not mutually exclusive) hypotheses have emerged. In the first, regular-spiking is inversely correlated to the density of low-voltage-gated potassium currents (I KL). In the second, regular spiking is directly correlated to the density of hyperpolarization-activated cyclic nucleotide-sensitive currents (I H). Supporting the idea that variations in ion channel composition shape spike-timing, VGNs from the first postnatal week respond to synaptic-noise-like current injections with irregular-firing patterns if they have I KL and with more regular firing patterns if they do not. However, in vitro firing patterns are not as regular as those in vivo Here we considered whether highly-regular spiking requires I H currents and whether this dependence emerges later in development after channel expression matures. We recorded from rat VGN somata of either sex aged postnatal day (P)9-P21. Counter to expectation, in vitro firing patterns were less diverse, more transient-spiking, and more irregular at older ages than at younger ages. Resting potentials hyperpolarized and resting conductance increased, consistent with developmental upregulation of I KL Activation of I H (by increasing intracellular cAMP) increased spike rates but not spike-timing regularity. In a model, we found that activating I H counter-intuitively suppressed regularity by recruiting I KL Developmental upregulation in I KL appears to overwhelm I H These results counter previous hypotheses about how I H shapes vestibular afferent responses.SIGNIFICANCE STATEMENT Vestibular sensory information is conveyed on parallel neuronal pathways with irregularly-firing neurons encoding information using a temporal code and regularly-firing neurons using a rate code. This is a striking example of spike-timing statistics influencing information coding. Previous studies from immature vestibular ganglion neurons (VGNs) identified hyperpolarization-activated mixed cationic currents (I H) as driving highly-regular spiking and proposed that this influence grows with the current during maturation. We found that I H becomes less influential, likely because maturing VGNs also acquire low-voltage-gated potassium currents (I KL), whose inhibitory influence opposes I H Because efferent activity can partly close I KL, VGN firing patterns may become more receptive to extrinsic control. Spike-timing regularity likely relies on dynamic ion channel properties and complementary specializations in synaptic connectivity.
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McInturff S, Burns JC, Kelley MW. Characterization of spatial and temporal development of Type I and Type II hair cells in the mouse utricle using new cell-type-specific markers. Biol Open 2018; 7:bio038083. [PMID: 30455179 PMCID: PMC6262869 DOI: 10.1242/bio.038083] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 09/14/2018] [Indexed: 12/16/2022] Open
Abstract
The utricle of the inner ear, a vestibular sensory structure that mediates perception of linear acceleration, is comprised of two morphologically and physiologically distinct types of mechanosensory hair cells, referred to as Type Is and Type IIs. While these cell types are easily discriminated in an adult utricle, understanding their development has been hampered by a lack of molecular markers that can be used to identify each cell type prior to maturity. Therefore, we collected single hair cells at three different ages and used single cell RNAseq to characterize the transcriptomes of those cells. Analysis of differential gene expression identified Spp1 as a specific marker for Type I hair cells and Mapt and Anxa4 as specific markers for Type II hair cells. Antibody labeling confirmed the specificity of these markers which were then used to examine the temporal and spatial development of utricular hair cells. While Type I hair cells develop in a gradient that extends across the utricle from posterior-medial to anterior-lateral, Type II hair cells initially develop in the central striolar region and then extend uniformly towards the periphery. Finally, by combining these markers with genetic fate mapping, we demonstrate that over 98% of all Type I hair cells develop prior to birth while over 98% of Type II hair cells develop post-natally. These results are consistent with previous findings suggesting that Type I hair cells develop first and refute the hypothesis that Type II hair cells represent a transitional form between immature and Type I hair cells.
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Affiliation(s)
- Stephen McInturff
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - Joseph C Burns
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - Matthew W Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
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Meredith FL, Rennie KJ. Regional and Developmental Differences in Na + Currents in Vestibular Primary Afferent Neurons. Front Cell Neurosci 2018; 12:423. [PMID: 30487736 PMCID: PMC6246661 DOI: 10.3389/fncel.2018.00423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/29/2018] [Indexed: 02/04/2023] Open
Abstract
The vestibular system relays information about head position via afferent nerve fibers to the brain in the form of action potentials. Voltage-gated Na+ channels in vestibular afferents drive the initiation and propagation of action potentials, but their expression during postnatal development and their contributions to firing in diverse mature afferent populations are unknown. Electrophysiological techniques were used to determine Na+ channel subunit types in vestibular calyx-bearing afferents at different stages of postnatal development. We used whole cell patch clamp recordings in thin slices of gerbil crista neuroepithelium to investigate Na+ channels and firing patterns in central zone (CZ) and peripheral zone (PZ) afferents. PZ afferents are exclusively dimorphic, innervating type I and type II hair cells, whereas CZ afferents can form dimorphs or calyx-only terminals which innervate type I hair cells alone. All afferents expressed tetrodotoxin (TTX)-sensitive Na+ currents, but TTX-sensitivity varied with age. During the fourth postnatal week, 200–300 nM TTX completely blocked sodium currents in PZ and CZ calyces. By contrast, in immature calyces [postnatal day (P) 5–11], a small component of peak sodium current remained in 200 nM TTX. Application of 1 μM TTX, or Jingzhaotoxin-III plus 200 nM TTX, abolished sodium current in immature calyces, suggesting the transient expression of voltage-gated sodium channel 1.5 (Nav1.5) during development. A similar TTX-insensitive current was found in early postnatal crista hair cells (P5–9) and constituted approximately one third of the total sodium current. The Nav1.6 channel blocker, 4,9-anhydrotetrodotoxin, reduced a component of sodium current in immature and mature calyces. At 100 nM 4,9-anhydrotetrodotoxin, peak sodium current was reduced on average by 20% in P5–14 calyces, by 37% in mature dimorphic PZ calyces, but by less than 15% in mature CZ calyx-only terminals. In mature PZ calyces, action potentials became shorter and broader in the presence of 4,9-anhydrotetrodotoxin implicating a role for Nav1.6 channels in firing in dimorphic afferents.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Katherine J Rennie
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Physiology & Biophysics, University of Colorado School of Medicine, Aurora, CO, United States
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Calyx junction dismantlement and synaptic uncoupling precede hair cell extrusion in the vestibular sensory epithelium during sub-chronic 3,3'-iminodipropionitrile ototoxicity in the mouse. Arch Toxicol 2018; 93:417-434. [PMID: 30377733 DOI: 10.1007/s00204-018-2339-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 10/23/2018] [Indexed: 10/28/2022]
Abstract
The cellular and molecular events that precede hair cell (HC) loss in the vestibular epithelium during chronic ototoxic exposure have not been widely studied. To select a study model, we compared the effects of sub-chronic exposure to different concentrations of 3,3'-iminodipropionitrile (IDPN) in the drinking water of two strains of mice and of both sexes. In subsequent experiments, male 129S1/SvImJ mice were exposed to 30 mM IDPN for 5 or 8 weeks; animals were euthanized at the end of the exposure or after a washout period of 13 weeks. In behavioral tests, IDPN mice showed progressive vestibular dysfunction followed by recovery during washout. In severely affected animals, light and electron microscopy observations of the vestibular epithelia revealed HC extrusion towards the endolymphatic cavity. Comparison of functional and ultrastructural data indicated that animals with fully reversible dysfunction did not have significant HC loss or stereociliary damage, but reversible dismantlement of the calyceal junctions that characterize the contact between type I HCs (HCI) and their calyx afferents. Immunofluorescent analysis revealed the loss of calyx junction proteins, Caspr1 and Tenascin-C, during exposure and their recovery during washout. Synaptic uncoupling was also recorded, with loss of pre-synaptic Ribeye and post-synaptic GluA2 puncta, and differential reversibility among the three different kinds of synaptic contacts existing in the epithelium. qRT-PCR analyses demonstrated that some of these changes are at least in part explained by gene expression modifications. We concluded that calyx junction dismantlement and synaptic uncoupling are early events in the mouse vestibular sensory epithelium during sub-chronic IDPN ototoxicity.
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Hartman BH, Bӧscke R, Ellwanger DC, Keymeulen S, Scheibinger M, Heller S. Fbxo2 VHC mouse and embryonic stem cell reporter lines delineate in vitro-generated inner ear sensory epithelia cells and enable otic lineage selection and Cre-recombination. Dev Biol 2018; 443:64-77. [PMID: 30179592 DOI: 10.1016/j.ydbio.2018.08.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/24/2018] [Accepted: 08/25/2018] [Indexed: 12/12/2022]
Abstract
While the mouse has been a productive model for inner ear studies, a lack of highly specific genes and tools has presented challenges. The absence of definitive otic lineage markers and tools is limiting in vitro studies of otic development, where innate cellular heterogeneity and disorganization increase the reliance on lineage-specific markers. To address this challenge in mice and embryonic stem (ES) cells, we targeted the lineage-specific otic gene Fbxo2 with a multicistronic reporter cassette (Venus/Hygro/CreER = VHC). In otic organoids derived from ES cells, Fbxo2VHC specifically delineates otic progenitors and inner ear sensory epithelia. In mice, Venus expression and CreER activity reveal a cochlear developmental gradient, label the prosensory lineage, show enrichment in a subset of type I vestibular hair cells, and expose strong expression in adult cerebellar granule cells. We provide a toolbox of multiple spectrally distinct reporter combinations for studies that require use of fluorescent reporters, hygromycin selection, and conditional Cre-mediated recombination.
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Affiliation(s)
- Byron H Hartman
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, United States.
| | - Robert Bӧscke
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Department of Otolaryngology, Head and Neck Surgery, University of Lübeck, Lübeck, Germany
| | - Daniel C Ellwanger
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Sawa Keymeulen
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Program in Human Biology, Stanford University School of Humanities and Sciences, Stanford, CA 94305, United States
| | - Mirko Scheibinger
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Stefan Heller
- Department of Otolaryngology - Head&Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, United States.
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47
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Rossi ML, Rubbini G, Martini M, Canella R, Fesce R. Pre- and Postsynaptic Effects of Glutamate in the Frog Labyrinth. Neuroscience 2018; 385:198-214. [PMID: 29913242 DOI: 10.1016/j.neuroscience.2018.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/06/2018] [Accepted: 06/08/2018] [Indexed: 11/20/2022]
Abstract
The role of glutamate in quantal release at the cytoneural junction was examined by measuring mEPSPs and afferent spikes at the posterior canal in the intact frog labyrinth. Release was enhanced by exogenous glutamate, or dl-TBOA, a blocker of glutamate reuptake. Conversely, drugs acting on ionotropic glutamate receptors did not affect release; the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) blocker CNQX decreased mEPSP size in a dose-dependent manner; the NMDA-R blocker d-AP5 at concentrations <200 µM did not affect mEPSP size, either in the presence or absence of Mg and glycine. In isolated hair cells, glutamate did not modify Ca currents. Instead, it systematically reduced the compound delayed potassium current, IKD, whereas the metabotropic glutamate receptor (mGluR)-II inverse agonist, (2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl)propanoic acid (LY341495), increased it. Given mGluR-II decrease cAMP production, these finding are consistent with the reported sensitivity of IKD to protein kinase A (PKA)-mediated phosphorylation. LY341495 also enhanced transmitter release, presumably through phosphorylation-mediated facilitation of the release machinery. The observed enhancement of release by glutamate confirms previous literature data, and can be attributed to activation of mGluR-I that promotes Ca release from intracellular stores. Glutamate-induced reduction in the repolarizing IKD may contribute to facilitation of release. Overall, glutamate exerts both a positive feedback action on mGluR-I, through activation of the phospholipase C (PLC)/IP3 path, and the negative feedback, by interfering with substrate phosphorylation through Gi/0-coupled mGluRs-II/III. The positive feedback prevails, which may explain the increase in overall rates of release observed during mechanical stimulation (symmetrical in the excitatory and inhibitory directions). The negative feedback may protect the junction from over-activation.
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Affiliation(s)
- Maria Lisa Rossi
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy.
| | - Gemma Rubbini
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Marta Martini
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Rita Canella
- Dipartimento di Scienze della Vita e Biotecnologie, Ferrara University, Ferrara, Italy
| | - Riccardo Fesce
- Centre of Neuroscience, DISTA, Insubria University, Varese, Italy
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Requena T, Gallego-Martinez A, Lopez-Escamez JA. Bioinformatic Integration of Molecular Networks and Major Pathways Involved in Mice Cochlear and Vestibular Supporting Cells. Front Mol Neurosci 2018; 11:108. [PMID: 29674954 PMCID: PMC5895758 DOI: 10.3389/fnmol.2018.00108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 03/19/2018] [Indexed: 12/18/2022] Open
Abstract
Background: Cochlear and vestibular epithelial non-hair cells (ENHCs) are the supporting elements of the cellular architecture in the organ of Corti and the vestibular neuroepithelium in the inner ear. Intercellular and cell-extracellular matrix interactions are essential to prevent an abnormal ion redistribution leading to hearing and vestibular loss. The aim of this study is to define the main pathways and molecular networks in the mouse ENHCs. Methods: We retrieved microarray and RNA-seq datasets from mouse epithelial sensory and non-sensory cells from gEAR portal (http://umgear.org/index.html) and obtained gene expression fold-change between ENHCs and non-epithelial cells (NECs) against HCs for each gene. Differentially expressed genes (DEG) with a log2 fold change between 1 and -1 were discarded. The remaining genes were selected to search for interactions using Ingenuity Pathway Analysis and STRING platform. Specific molecular networks for ENHCs in the cochlea and the vestibular organs were generated and significant pathways were identified. Results: Between 1723 and 1559 DEG were found in the mouse cochlear and vestibular tissues, respectively. Six main pathways showed enrichment in the supporting cells in both tissues: (1) "Inhibition of Matrix Metalloproteases"; (2) "Calcium Transport I"; (3) "Calcium Signaling"; (4) "Leukocyte Extravasation Signaling"; (5) "Signaling by Rho Family GTPases"; and (6) "Axonal Guidance Si". In the mouse cochlea, ENHCs showed a significant enrichment in 18 pathways highlighting "axonal guidance signaling (AGS)" (p = 4.37 × 10-8) and "RhoGDI Signaling" (p = 3.31 × 10-8). In the vestibular dataset, there were 20 enriched pathways in ENHCs, the most significant being "Leukocyte Extravasation Signaling" (p = 8.71 × 10-6), "Signaling by Rho Family GTPases" (p = 1.20 × 10-5) and "Calcium Signaling" (p = 1.20 × 10-5). Among the top ranked networks, the most biologically significant network contained the "auditory and vestibular system development and function" terms. We also found 108 genes showing tonotopic gene expression in the cochlear ENHCs. Conclusions: We have predicted the main pathways and molecular networks for ENHCs in the organ of Corti and vestibular neuroepithelium. These pathways will facilitate the design of molecular maps to select novel candidate genes for hearing or vestibular loss to conduct functional studies.
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Affiliation(s)
- Teresa Requena
- Otology & Neurotology Group CTS495, Department of Genomic Medicine-Centro de Genómica e Investigación Oncológica-Pfizer/Universidad de Granada/Junta de Andalucía (GENYO), Granada, Spain
| | - Alvaro Gallego-Martinez
- Otology & Neurotology Group CTS495, Department of Genomic Medicine-Centro de Genómica e Investigación Oncológica-Pfizer/Universidad de Granada/Junta de Andalucía (GENYO), Granada, Spain
| | - Jose A Lopez-Escamez
- Otology & Neurotology Group CTS495, Department of Genomic Medicine-Centro de Genómica e Investigación Oncológica-Pfizer/Universidad de Granada/Junta de Andalucía (GENYO), Granada, Spain.,Department of Otolaryngology, Instituto de Investigación Biosanitaria, ibs.GRANADA, Hospital Virgen de las Nieves, Universidad de Granada, Granada, Spain.,Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg
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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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Spaiardi P, Tavazzani E, Manca M, Milesi V, Russo G, Prigioni I, Marcotti W, Magistretti J, Masetto S. An allosteric gating model recapitulates the biophysical properties of I K,L expressed in mouse vestibular type I hair cells. J Physiol 2017; 595:6735-6750. [PMID: 28862328 PMCID: PMC5663832 DOI: 10.1113/jp274202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 08/30/2017] [Indexed: 12/11/2022] Open
Abstract
Key points Vestibular type I and type II hair cells and their afferent fibres send information to the brain regarding the position and movement of the head. The characteristic feature of type I hair cells is the expression of a low‐voltage‐activated outward rectifying K+ current, IK,L, whose biophysical properties and molecular identity are still largely unknown. In vitro, the afferent nerve calyx surrounding type I hair cells causes unstable intercellular K+ concentrations, altering the biophysical properties of IK,L. We found that in the absence of the calyx, IK,L in type I hair cells exhibited unique biophysical activation properties, which were faithfully reproduced by an allosteric channel gating scheme. These results form the basis for a molecular and pharmacological identification of IK,L.
Abstract Type I and type II hair cells are the sensory receptors of the mammalian vestibular epithelia. Type I hair cells are characterized by their basolateral membrane being enveloped in a single large afferent nerve terminal, named the calyx, and by the expression of a low‐voltage‐activated outward rectifying K+ current, IK,L. The biophysical properties and molecular profile of IK,L are still largely unknown. By using the patch‐clamp whole‐cell technique, we examined the voltage‐ and time‐dependent properties of IK,L in type I hair cells of the mouse semicircular canal. We found that the biophysical properties of IK,L were affected by an unstable K+ equilibrium potential (VeqK+). Both the outward and inward K+ currents shifted VeqK+ consistent with K+ accumulation or depletion, respectively, in the extracellular space, which we attributed to a residual calyx attached to the basolateral membrane of the hair cells. We therefore optimized the hair cell dissociation protocol in order to isolate mature type I hair cells without their calyx. In these cells, the uncontaminated IK,L showed a half‐activation at –79.6 mV and a steep voltage dependence (2.8 mV). IK,L also showed complex activation and deactivation kinetics, which we faithfully reproduced by an allosteric channel gating scheme where the channel is able to open from all (five) closed states. The ‘early’ open states substantially contribute to IK,L activation at negative voltages. This study provides the first complete description of the ‘native’ biophysical properties of IK,L in adult mouse vestibular type I hair cells. Vestibular type I and type II hair cells and their afferent fibres send information to the brain regarding the position and movement of the head. The characteristic feature of type I hair cells is the expression of a low‐voltage‐activated outward rectifying K+ current, IK,L, whose biophysical properties and molecular identity are still largely unknown. In vitro, the afferent nerve calyx surrounding type I hair cells causes unstable intercellular K+ concentrations, altering the biophysical properties of IK,L. We found that in the absence of the calyx, IK,L in type I hair cells exhibited unique biophysical activation properties, which were faithfully reproduced by an allosteric channel gating scheme. These results form the basis for a molecular and pharmacological identification of IK,L.
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Affiliation(s)
- Paolo Spaiardi
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
| | - Elisa Tavazzani
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
| | - Marco Manca
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
| | - Veronica Milesi
- Instituto de Estudios Inmunológios y Fisiopatológicos (IIFP) - CONICET, Universidad Nacional de La Plata, La Plata, 1900, Argentina
| | - Giancarlo Russo
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
| | - Ivo Prigioni
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jacopo Magistretti
- Department of Biology and Biotechnology, University of Pavia, Pavia, 27100, Italy
| | - Sergio Masetto
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, 27100, Italy
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