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Wu S, Zhang YF, Gui Y, Jiang T, Zhou CM, Li JY, Suo JL, Li YN, Jin RL, Li SL, Cui JY, Tan BH, Li YC. A detection method for neuronal death indicates abnormalities in intracellular membranous components in neuronal cells that underwent delayed death. Prog Neurobiol 2023; 226:102461. [PMID: 37179048 DOI: 10.1016/j.pneurobio.2023.102461] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 03/20/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023]
Abstract
Acute neuronal degeneration is always preceded under the light and electron microscopes by a stage called microvacuolation, which is characterized by a finely vacuolar alteration in the cytoplasm of the neurons destined to death. In this study, we reported a method for detecting neuronal death using two membrane-bound dyes, rhodamine R6 and DiOC6(3), which may be associated with the so-called microvacuolation. This new method produced a spatiotemporally similar staining pattern to Fluoro-Jade B in kainic acid-damaged brains in mice. Further experiments showed that increased staining of rhodamine R6 and DiOC6(3) was observed only in degenerated neurons, but not in glia, erythrocytes, or meninges. Different from Fluoro-Jade-related dyes, rhodamine R6 and DiOC6(3) staining is highly sensitive to solvent extraction and detergent exposure. Staining with Nile red for phospholipids and filipin III for non-esterified cholesterol supports that the increased staining of rhodamine R6 and DiOC6(3) might be associated with increased levels of phospholipids and free cholesterol in the perinuclear cytoplasm of damaged neurons. In addition to kainic acid-injected neuronal death, rhodamine R6 and DiOC6(3) were similarly useful for detecting neuronal death in ischemic models either in vivo or in vitro. As far as we know, the staining with rhodamine R6 or DiOC6(3) is one of a few histochemical methods for detecting neuronal death whose target molecules have been well defined and therefore may be useful for explaining experimental results as well as exploring the mechanisms of neuronal death. (250 words).
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Affiliation(s)
- Shuang Wu
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Yan-Feng Zhang
- Department of Pediatric Neurology, First Hospital of Jilin University, Changchun, Jilin Province 130021, PR China
| | - Yue Gui
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Tian Jiang
- Department of Emergency and Critical Care Medicine, The Second Hospital of Jilin University, Jilin Province 130041, PR China
| | - Cheng-Mei Zhou
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Jing-Yi Li
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Jia-Le Suo
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Yong-Nan Li
- Department of Neurology, Fourth Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province 150001, PR China
| | - Rui-Lin Jin
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Shu-Lei Li
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Jia-Yue Cui
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Bai-Hong Tan
- Laboratory Teaching Center of Basic Medicine, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China
| | - Yan-Chao Li
- Department of Histology and Embryology, College of Basic Medical Sciences, Norman Bethune Health Science Center of Jilin University, Jilin Province 130021, PR China.
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Raphael RM. Outer Hair Cell Electromechanics as a Problem in Soft Matter Physics: Prestin, the Membrane and the Cytoskeleton. Hear Res 2021; 423:108426. [DOI: 10.1016/j.heares.2021.108426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 11/28/2022]
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3
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Bell A. Detection without deflection? A hypothesis for direct sensing of sound pressure by hair cells. J Biosci 2008; 32:385-404. [PMID: 17435329 DOI: 10.1007/s12038-007-0037-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
It is widely thought that organisms detect sound by sensing the deflection of hair-like projections, the stereocilia, at the apex of hair cells. In the case of mammals, the standard interpretation is that hair cells in the cochlea respond to deflection of stereocilia induced by motion generated by a hydrodynamic travelling wave. But in the light of persistent anomalies, an alternative hypothesis seems to have some merit: that sensing cells (in particular the outer hair cells) may, at least at low intensities, be reacting to a different stimulus - the rapid pressure wave that sweeps through the cochlear fluids at the speed of sound in water. This would explain why fast responses are sometimes seen before the peak of the travelling wave. Yet how could cells directly sense fluid pressure? Here, a model is constructed of the outer hair cell as a pressure vessel able to sense pressure variations across its cuticular pore, and this 'fontanelle' model, based on the sensing action of the basal body at this compliant spot, could explain the observed anomalies. Moreover, the fontanelle model can be applied to a wide range of other organisms, suggesting that direct pressure detection is a general mode of sensing complementary to stereociliar displacement.
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Affiliation(s)
- Andrew Bell
- Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia.
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4
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Ning Y, Suo–qiang Z, Shi–ming Y, Dong–yi H, Hong–bo Z. Distribution of Prestin on Outer Hair Cell Basolateral Surface. J Otol 2008. [DOI: 10.1016/s1672-2930(08)50020-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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5
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Jensen-Smith H, Hallworth R. Lateral wall protein content mediates alterations in cochlear outer hair cell mechanics before and after hearing onset. ACTA ACUST UNITED AC 2007; 64:705-17. [PMID: 17615570 PMCID: PMC1992524 DOI: 10.1002/cm.20217] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Specialized outer hair cells (OHCs) housed within the mammalian cochlea exhibit active, nonlinear, mechanical responses to auditory stimulation termed electromotility. The extraordinary frequency resolution capacity of the cochlea requires an exquisitely equilibrated mechanical system of sensory and supporting cells. OHC electromotile length change, stiffness, and force generation are responsible for a 100-fold increase in hearing sensitivity by augmenting vibrational input to non-motile sensory inner hair cells. Characterization of OHC mechanics is crucial for understanding and ultimately preventing permanent functional deficits due to overstimulation or as a consequence of various cochlear pathologies. The OHCs' major structural assembly is a highly-specialized lateral wall. The lateral wall consists of three structures; a plasma membrane highly-enriched with the motor-protein prestin, an actin-spectrin cortical lattice, and one or more layers of subsurface cisternae. Technical difficulties in independently manipulating each lateral wall constituent have constrained previous attempts to analyze the determinants of OHCs' mechanical properties. Temporal separations in the accumulation of each lateral wall constituent during postnatal development permit associations between lateral wall structure and OHC mechanics. We compared developing and adult gerbil OHC axial stiffness using calibrated glass fibers. Alterations in each lateral wall component and OHC stiffness were correlated as a function of age. Reduced F-actin labeling was correlated with reduced OHC stiffness before hearing onset. Prestin incorporation into the PM was correlated with increased OHC stiffness at hearing onset. Our data indicate lateral wall F-actin and prestin are the primary determinants of OHC mechanical properties before and after hearing onset, respectively.
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Affiliation(s)
- Heather Jensen-Smith
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska 68178, USA.
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6
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Grant L, Slapnick S, Kennedy H, Hackney C. Ryanodine receptor localisation in the mammalian cochlea: an ultrastructural study. Hear Res 2006; 219:101-9. [PMID: 16889917 DOI: 10.1016/j.heares.2006.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 06/05/2006] [Accepted: 06/12/2006] [Indexed: 10/24/2022]
Abstract
Calcium-induced calcium release (CICR) in the mammalian cochlea has been suggested to enhance neurotransmitter release from inner hair cells and facilitate the efferent response in outer hair cells. Light microscopic evidence exists for the presence of ryanodine receptors in the organ of Corti but there is so far no information about their ultrastructural localisation. We have therefore used post-embedding immunogold labeling with antibodies that predominantly recognise ryanodine receptor isoforms 1 (RyR1) and 2 (RyR2) to investigate their distribution in rat cochleae. In inner hair cells, the highest levels of labeling were observed over an area of rough endoplasmic reticulum that lies in the cytoplasmic region beneath the nucleus; in outer hair cells, the cytoplasmic region above the nucleus displayed most labeling. Labeling was also associated with the subsurface cisternae adjacent to the lateral membranes of both types of hair cell, with the efferent terminals on the outer hair cells and was observed in adjacent supporting cells. Labeling in outer hair cells was significantly higher than that in inner hair cells or in the supporting cells. Our results support the presence of RyR1 in the cochlea but do not rule out the presence of other isoforms. CICR may be involved in the control of calcium levels in the base of the inner hair cells and supporting cells, and in the cholinergic efferent response and motile behaviour of the outer hair cells.
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Affiliation(s)
- Lisa Grant
- Department of Physiology, University of Bristol, Bristol, UK.
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7
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He DZZ, Zheng J, Kalinec F, Kakehata S, Santos-Sacchi J. Tuning in to the amazing outer hair cell: membrane wizardry with a twist and shout. J Membr Biol 2006; 209:119-34. [PMID: 16773497 DOI: 10.1007/s00232-005-0833-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Indexed: 11/29/2022]
Affiliation(s)
- D Z Z He
- Hair Cell Biophysics Laboratory, Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
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8
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Yu N, Zhu ML, Zhao HB. Prestin is expressed on the whole outer hair cell basolateral surface. Brain Res 2006; 1095:51-8. [PMID: 16709400 PMCID: PMC2548272 DOI: 10.1016/j.brainres.2006.04.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 04/03/2006] [Accepted: 04/03/2006] [Indexed: 10/24/2022]
Abstract
Prestin has been identified as a motor protein responsible for outer hair cell (OHC) electromotility. Previous experiments revealed that OHC electromotility and its associated nonlinear capacitance resided in the OHC lateral wall and was not detected at the apical cuticular plate and basal region. In this experiment, the distribution of prestin in adult mouse, rat, and guinea pig OHCs was re-examined by use of immunofluorescent staining and confocal microscopy. We found that prestin labeling was located at the whole OHC basolateral wall, including the basal plasma membrane. However, staining at the basal membrane was weak. As compared with the intensity at the lateral wall, the intensities of prestin labeling at the membrane at the nuclear level and basal pole were 80.5% and 61.1%, respectively. Prestin labeling was not found at the cuticular plate and stereocilia. The prestin labeling was also absent in the cytoplasm and nuclei. The OHC lateral wall above the nuclear level is composed of the plasma membrane, cortical lattice, and subsurface cisternae. By co-staining with di-8-ANEPPS, prestin labeling was found at the outer layer of the OHC lateral wall, which was further evidenced by use of a hypotonic challenge to separate the plasma membrane from the underlying subsurface cisternae. The data revealed that prestin is expressed at the whole OHC basolateral membrane. Prestin in the basal plasma membrane may provide a reservoir on the OHC surface for prestin-recycling and may also facilitate performing its hypothesized transporter function.
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Affiliation(s)
| | | | - Hong-Bo Zhao
- Corresponding author. Fax: +1 859 257 5096., E-mail address: (H.-B. Zhao)
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9
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Griesinger CB, Richards CD, Ashmore JF. Apical endocytosis in outer hair cells of the mammalian cochlea. Eur J Neurosci 2004; 20:41-50. [PMID: 15245477 DOI: 10.1111/j.0953-816x.2004.03452.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Outer hair cells (OHCs), the sensory-motor cells of the mammalian cochlea, contain an endocytic tubulovesicular compartment below their apical stereocilia. We have used two-photon imaging of FM1-43 in the intact epithelium to show that these cells take up membrane in a Ca(2+)-dependent manner from a distinct apical site. The uptake rate was 0.8 microm(2)/s and internalized membrane was trafficked rapidly to a compartment along the lateral wall and distinct intracellular compartments. Double labelling with FM1-43 and DiOC(6), an endoplasmic reticulum (ER) marker, showed that these compartments are part of the tubulovesicular endoplasmic reticulum of OHCs. Labelling with a lysosomal marker showed that OHC lysosomes are restricted to the apex. Using the protein marker wheat germ agglutinin (WGA-FITC) we demonstrate that apical protein internalization and trafficking is about eight times slower than membrane internalization. Using double labelling with FM1-43 and WGA-FITC, we show that membrane and protein internalization are apically colocalized but that patterns of protein and membrane traffic differ. Protein was targeted only to the most apical third of the lateral wall. In control conditions, OHCs displayed only weak WGA-FITC surface labelling at the site of endocytosis. Lowering the rate of apical endocytosis increased this surface signal. The results suggest that OHCs endocytose membrane and membrane proteins with a high turnover rate and that these cells may use apical endocytosis to sort proteins via an indirect pathway to the lateral membrane.
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Affiliation(s)
- C B Griesinger
- Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK.
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10
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Abstract
The role of the cochlea is to transduce complex sound waves into electrical neural activity in the auditory nerve. Hair cells of the organ of Corti are the sensory cells of hearing. The inner hair cells perform the transduction and initiate the depolarization of the spiral ganglion neurons. The outer hair cells are accessory sensory cells that enhance the sensitivity and selectivity of the cochlea. Neural feedback loops that bring efferent signals to the outer hair cells assist in sharpening and amplifying the signals. The stria vascularis generates the endocochlear potential and maintains the ionic composition of the endolymph, the fluid in which the apical surface of the hair cells is bathed. The mechanical characteristics of the basilar membrane and its related structures further enhance the frequency selectivity of the auditory transduction mechanism. The tectorial membrane is an extracellular matrix, which provides mass loading on top of the organ of Corti, facilitating deflection of the stereocilia. This review deals with the structure of the normal mature mammalian cochlea and includes recent data on the molecular organization of the main cell types within the cochlea.
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Affiliation(s)
- Yehoash Raphael
- Kresge Hearing Research Institute, The University of Michigan, MSRB 3, Rm 9303, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0648, USA.
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11
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Abstract
The inner ear is structurally complex. A molecular description of its architecture is now emerging from the use of contemporary methods of cell and molecular biology, and from studies of ontogenetic development. With the application of clinical and molecular genetics, it has now become possible to identify genes associated with inherited, non-syndromic deafness and balance dysfunction in humans and in mice. This work is providing new insights into how the tissues of the inner ear are built to perform their tasks, and into the pathogenesis of a range of inner ear disorders.
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Affiliation(s)
- Andrew Forge
- UCL Centre for Auditory Research and Institute of Laryngology & Otology, University College London, UK
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12
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Abstract
Endocytosis in cochlear hair cells was investigated by staining with the vital fluorescent dye FM 1-43, that partitions reversibly into membranes and is trapped in vesicles during endocytosis. The temporal development and spatial distribution of FM 1-43 induced fluorescence was investigated using confocal laser-scanning microscopy. FM 1-43 rapidly and intensely stained cochlear hair cells, leaving the supporting cells unstained. For short application (0.2-30 s), only the infracuticular region of outer hair cells (OHCs) was labeled, whereas for long application (30-60 s), the OHCs were also labeled in the infranuclear zone and along a central strand extending from the infracuticular zone down to the nucleus, as well as along the entire cell membrane. Except for the cell membrane, the infracuticular zone, directly below the cuticular plate, showed the most rapid and intense staining, and in most cases staining was spherically shaped with a diameter of 3-7 microm. Localization and size of this infracuticular staining coincided with Hensen's body, a specialized variant of the endoplasmic reticulum. In contrast to the OHCs, apical fluorescence of inner hair cells presented a homogeneous distribution. When OHCs were incubated in FM 1-43 for longer than 1 min, many points of contact between the central strand, the infracuticular zone and the lateral cell membrane were observed. Since Hensen's bodies are a specialty of OHCs and the fluorescent staining pattern of these cells was unique, it is proposed that Hensen's body is involved in the turnover of OHC-specific proteins, such as those involved in the molecular machinery of the motor action of the plasma membrane.
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Affiliation(s)
- J Meyer
- Department of Otolaryngology, Section of Physiological Acoustics and Communication, University of Tübingen, Germany
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Kalinec F, Zhang M, Urrutia R, Kalinec G. Rho GTPases mediate the regulation of cochlear outer hair cell motility by acetylcholine. J Biol Chem 2000; 275:28000-5. [PMID: 10862776 DOI: 10.1074/jbc.m004917200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Outer hair cells are the mechanical effectors of the cochlear amplifier, an active process that improves the sensitivity and frequency discrimination of the mammalian ear. In vivo, the gain of the cochlear amplifier is regulated by the efferent neurotransmitter acetylcholine through the modulation of outer hair cell motility. Little is known, however, regarding the molecular mechanisms activated by acetylcholine. In this study, intracellular signaling pathways involving the small GTPases RhoA, Rac1, and Cdc42 have been identified as regulators of outer hair cell motility. Changes in cell length (slow motility) and in the amplitude of electrically induced movement (fast motility) were measured in isolated outer hair cells patch clamped in whole-cell mode, internally perfused through the patch pipette with different inhibitors and activators of these small GTPases while being externally stimulated with acetylcholine. We found that acetylcholine induces outer hair cell shortening and a simultaneous increase in the amplitude of fast motility through Rac1 and Cdc42 activation. In contrast, a RhoA- and Rac1-mediated signaling pathway induces outer hair cell elongation and decreases fast motility amplitude. These two opposing processes provide the basis for a regulatory mechanism of outer hair cell motility.
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Affiliation(s)
- F Kalinec
- Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, California 90057, USA.
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14
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Abstract
Micropipette aspiration was used to study the lateral wall stiffness of isolated guinea pig outer hair cells (OHCs) perfused with a sodium salicylate solution. Salicylate treatment significantly decreased lateral wall stiffness as measured by a stiffness parameter (S) compared to cells perfused with a standard bathing solution (S = 0.68 +/- 0.26 vs. S= 1.09 +/- 0.25, P < 0.05). The effect was reversible cells treated with salicylate and then with bathing solution exhibited a lateral wall stiffness similar to control cells (S = 1.10 +/- 0.40. P=0.94). Salicylate perfusion diminishes electromotile responses in isolated OHCs and physiologic doses of salicylate produce hearing loss and tinnitus in human subjects. The OHC lateral wall, the locus of electromotility, consists of three concentric layers: (1) an outermost plasma membrane, (2) a cytoskeletal network of actin and spectrin called the cortical lattice and (3) an innermost collection of flattened membranes called the subsurface cisternae (SSC). Ultrastructural studies have shown that salicylate treatment dilates and vesiculates the lateral wall subsurface cisternae (SSC) in guinea pig OHCs. In addition, salicylate causes an outward curvature of plasma membranes in human erythrocytes. The reversible, salicylate induced increase in lateral wall compliance may result from a direct action on the SSC and/or the plasma membrane.
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Affiliation(s)
- A J Lue
- Baylor College of Medicine, Bobby R. Alford Department of Otorhinolaryngology and Communicative Sciences, Houston, TX 77030, USA.
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15
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Tolomeo JA, Steele CR, Holley MC. Mechanical properties of the lateral cortex of mammalian auditory outer hair cells. Biophys J 1996; 71:421-9. [PMID: 8804625 PMCID: PMC1233493 DOI: 10.1016/s0006-3495(96)79244-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mammalian auditory outer hair cells generate high-frequency mechanical forces that enhance sound-induced displacements of the basilar membrane within the inner ear. It has been proposed that the resulting cell deformation is directed along the longitudinal axis of the cell by the cortical cytoskeleton. We have tested this proposal by making direct mechanical measurements on outer hair cells. The resultant stiffness modulus along the axis of whole dissociated cells was 3 x 10(-3) N/m, consistent with previously published values. The resultant axial and circumferential stiffness moduli for the cortical lattice were 5 x 10(-4) N/m and 3 x 10(-3) N/m, respectively. Thus the cortical lattice is a highly orthotropic structure. Its axial stiffness is small compared with that of the intact cell, but its circumferential stiffness is within the same order of magnitude. These measurements support the theory that the cortical cytoskeleton directs electrically driven length changes along the longitudinal axis of the cell. The Young's modulus of the circumferential filamentous components of the lattice were calculated to be 1 x 10(7) N/m2. The axial cross-links, believed to be a form of spectrin, were calculated to have a Young's modulus of 3 x 10(6) N/m2. Based on the measured values for the lattice and intact cell cortex, an estimate for the resultant stiffness modulus of the plasma membrane was estimated to be on the order of 10(-3) N/m. Thus, the plasma membrane appears to be relatively stiff and may be the dominant contributor to the axial stiffness of the intact cell.
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Affiliation(s)
- J A Tolomeo
- Department of Physiology, University of Bristol, England
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Dodson HC, Piper TA, Clarke JD, Quinlivan RM, Dickson G. Dystrophin expression in the hair cells of the cochlea. JOURNAL OF NEUROCYTOLOGY 1995; 24:625-32. [PMID: 7595670 DOI: 10.1007/bf01257377] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dystrophin is normally expressed in a number of tissues including muscle, brain and the outer plexiform layer of the retina. In Duchenne and Becker muscular dystrophy abnormal or deficient dystrophin expression leads to muscle degeneration and has been implicated in mental retardation and a form of night blindness. We have examined the expression of dystrophin immunoreactivity in cochlear tissues of normal guinea-pig and mouse, and whether expression is perturbed in the cochlea of the dystrophic MDX mouse. A single band of approximately 427 kDa, corresponding to a full-length isoform of dystrophin was detected in guinea-pig and normal mouse but was absent from the MDX mouse. Cochleae from guinea-pig, normal and MDX mouse also showed a second dystrophin isoform of 116 kDa molecular weight with the C-terminal specific antibody. Immunostained guinea pig cochlear half turns were examined by laser scanning confocal microscopy. Dystrophin was localized in both inner and outer hair cells with staining patterns which were qualitatively similar with both antibodies. In the outer hair cells labelling of the lateral wall was especially distinctive. The synaptic region of both hair cell types was also strongly labelled.
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Affiliation(s)
- H C Dodson
- Institute of Laryngology and Otology, University College London, UK
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19
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Lenoir M, Ripoll C, Vago P. Structural and ultrastructural aspects of isolated immature cochlear outer hair cells maintained in short-term culture. Hear Res 1995; 88:169-80. [PMID: 8575992 DOI: 10.1016/0378-5955(95)00110-p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Immature outer hair cells (OHCs), isolated from developing rat cochlea without using proteolytic enzymes, were maintained in short-term culture in a clot of coagulated plasma. Cell viability was assessed by a laser scanning image cytometer, using double-fluorescent labeling. Light and transmission electron microscopy was used to study the morphology of isolated cells. Ten to 60 healthy OHCs were obtained from one cochlea, either as single isolated cells or clusters containing 2-10 cells from the same row. Although dead cells were observed only 1 h after dissociation, there were still viable cells after 6 h. Isolated OHCs were not perfectly cylindrical, due to the immaturity of their cortical structures. One hour after dissociation the ultrastructural organization of the isolated cells was generally well preserved, but this was followed by dilatation of the Golgi apparatus and endoplasmic reticulum. Specific changes in isolated OHCs were also observed at the subsurface cisternae and cuticular plate. Although degenerating OHCs generally showed a classic pattern of necrosis, certain morphological features reminiscent of apoptosis were also observed. This study emphasises the difficulty involved in investigating isolated immature OHCs in vitro and provides a basis for future research into the physiological requirements of isolated immature OHCs.
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Affiliation(s)
- M Lenoir
- INSERM U254, Montpellier, France
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20
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Abstract
Many features of cochlear anatomy vary systematically radially and longitudinally within the organ of Corti. There is limited evidence that along the longitudinal axis of the cochlea the thickness of the subsurface cisternal system in the outer hair cells (OHCs) changes. Similarly a radial gradient may exist. The thickness of the subsurface cisternal system in OHCs was measured in gerbils to determine if there are differences between the three rows of OHCs and in OHCs in different locations along the length of the organ of Corti. The results suggest that there is a longitudinal as well as a radial gradient of subsurface cisternal system thickness. These gradients are the inverse to those for efferent innervation of OHCs. It is possible that these differences may contribute to the increased susceptibility to trauma and ototoxic compounds characteristic of the innermost and basalmost OHCs.
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Affiliation(s)
- C Lutz
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, KY 40292, USA
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21
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Holley MC, Richardson GP. Monoclonal antibodies specific for endoplasmic membranes of mammalian cochlear outer hair cells. JOURNAL OF NEUROCYTOLOGY 1994; 23:87-96. [PMID: 8195814 DOI: 10.1007/bf01183864] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Monoclonal antibodies were raised in vitro against an antigen associated with the lateral cisternal membranes of outer hair cells. Two of the antibodies were class IgM and one of these retained its specific reactivity in tissue fixed with aldehydes and embedded in the resin LR White. Immunogold labelling for electron microscopy showed that the antigen was closely associated with the membranes rather than the cytoplasmic or lumenal regions of the cisternae. The third antibody was an IgG. All three weakly labelled a protein band with an apparent molecular weight of about 60 kD on a Western blot. The antibodies did not cross-react with any other cell in the organ of Corti, including the inner hair cells. Furthermore, they showed no cross-reactivity with skeletal muscle, kidney, gut, brain, skin, blood or retina from the guinea pig. The results suggest that the lateral cisternae in outer hair cells may be functionally different from those of inner hair cells. The antibodies may provide useful markers for outer hair cells in studies of hair cell regeneration.
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Affiliation(s)
- M C Holley
- Department of Physiology, School of Medical Sciences, University Walk, Bristol, UK
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22
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Abstract
We examined the properties of outer hair cell (OHC) lateral wall membranes by application of 2 fluorescent membrane probes. The markers, C6-NBD-Ceramide and DiOC6, have been used in other cell types to label Golgi apparatus and endoplasmic reticulum, respectively. In living isolated OHCs NBD-Ceramide demonstrated uninterrupted fluorescence along the OHC lateral wall, while DiOC6 labeling proved punctate and notably less uniform in this region. In aldehyde-fixed isolated OHCs both probes exhibited distinct, continuous lateral wall fluorescence. Fixed preparations of the organ of Corti labeled with each probe demonstrated diffuse fluorescence throughout the inner hair cell cytoplasm unlike the uniform, circumferential lateral wall fluorescence seen in OHCs. OHCs exposed to salicylate following NBD-Ceramide labeling displayed patchy, less distinct labeling along the OHC lateral wall. The thickness of lateral wall fluorescence in salicylate exposed cells was 49% greater than control OHCs. We interpreted the salicylate induced change in lateral wall labeling as a fluorescent representation of previously described ultrastructural dilatation and vesiculation of the subsurface cisternae. The distribution of these 2 fluorescent probes along OHC lateral wall membranes suggests that the OHC's subsurface cisternae are neither Golgi nor ER, but share characteristics of both.
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Affiliation(s)
- P A Pollice
- Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196
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