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Tian C, Yang Y, Li Y, Sun F, Qu J, Zha D. Expression and localization of α 2A-adrenergic receptor in the rat post-natal developing cochlea. Eur J Histochem 2023; 67:3748. [PMID: 37548252 PMCID: PMC10476538 DOI: 10.4081/ejh.2023.3748] [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: 04/11/2023] [Accepted: 07/22/2023] [Indexed: 08/08/2023] Open
Abstract
Lots of adrenergic receptors (ARs) are widely present across the auditory pathways and are positioned to affect auditory and vestibular functions. However, noradrenergic regulation in the cochlea has not been well characterized. In this study, a rat model of noise-induced hearing loss was developed to investigate the expression of α2A-adrenergic receptor (AR) after acoustic trauma, then, we investigated the expression of α2A-AR in the developing rat cochlea using immunofluorescence, qRT-PCR, and Western blotting. We found that the expression of α2A-AR significantly increased in rats exposed to noise compared with controls. Immunofluorescence analysis demonstrated that α2A-AR is localized on hair cells (HCs), spiral ganglion neurons (SGNs), and the stria vascularis (SV) in the postnatal developing cochlea from post-natal day (P) 0 to P28. Furthermore, we observed α2A-AR mRNA reached a maximum level at P14 and P28 when compared with P0, while no significant differences in α2A-AR protein levels at the various stages when compared with P0. This study provides direct evidence for the expression of α2A-AR in HCs, SGNs, and the SV of the cochlea, indicating that norepinephrine might play a vital role in hearing function within the cochlea through α2A-AR.
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Affiliation(s)
- Chaoyong Tian
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
| | - Yang Yang
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
| | - Yao Li
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
| | - Fei Sun
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
| | - Juan Qu
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
| | - Dingjun Zha
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Air Force Medical University, Xi'an, Shannxi Province.
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Ishii M, Ishiyama G, Ishiyama A, Kato Y, Mochizuki F, Ito Y. Relationship Between the Onset of Ménière's Disease and Sympathetic Hyperactivity. Front Neurol 2022; 13:804777. [PMID: 35370896 PMCID: PMC8970286 DOI: 10.3389/fneur.2022.804777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/21/2022] [Indexed: 12/03/2022] Open
Abstract
Objective The pathogenesis of Ménière's disease is still largely unknown; however, it is known to be strongly associated with stress. Excessive stress can cause hyperactivity of the sympathetic autonomic nervous system. With the aim of understanding changes in sympathetic hyperactivity before and after Ménière's disease, we compared autonomic nervous function in patients in a stable phase of Ménière's disease and that in healthy adults. We also gathered data over about 10 years on autonomic nervous function immediately before a Ménière's attack. Study Design Prospective study. Patients Autonomic nervous function was analyzed in 129 patients in a stable phase of Ménière's disease 31 healthy adult volunteers. In nine patients, autonomic nervous function was also measured immediately before and after treatment of a vertigo attack. Main Outcome Measure Power spectrum analysis of heart rate variability (HRV) of EEG/ECG and an infrared electronic pupillometer were used. Sympathetic and parasympathetic nervous function was measured. Results There were no statistically significant differences in autonomic nervous function determined by HRV and electronic pupillometry between patients in a stable phase of Ménière's disease and healthy adults. Sympathetic function as measured by electronic pupillometry parameters VD and T5 showed no difference between the affected and unaffected sides in the baseline data measured in the stable phase (VD: affected side is 31.02 ± 6.16 mm/sec, unaffected side is 29.25 ± 5.73 mm/sec; T5: affected side is 3.37 ± 0.43 msec, unaffected side is 3.25 ± 0.39 msec). In contrast, all nine patients whose HRV data had been obtained just before an attack showed marked suppression of the parasympathetic nervous system and activation of the sympathetic nervous system. Electronic pupillometry also revealed an overactivation of the sympathetic nervous system on the affected side, just before the attacks. Analysis of sequential changes after the onset of an attack revealed that overactivation on the affected side was reduced after treatment, and no difference between affected and unaffected sides was observed 3 days after treatment. Conclusion Detailed analysis of autonomic nervous function showed that immediately before an attack of Ménière's disease, the sympathetic nervous system on the affected side was strongly overactivated.
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Affiliation(s)
- Masanori Ishii
- Department of Otorhinolaryngology, Japan Community Health Care Organization (JCHO) Tokyo Shinjuku Medical Center, Tokyo, Japan
- Department of Otorhinolaryngology and Head & Neck Surgery, The Jikei University School of Medicine, Tokyo, Japan
- *Correspondence: Masanori Ishii
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Akira Ishiyama
- Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Yujin Kato
- Department of Otorhinolaryngology and Head & Neck Surgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Fumihiro Mochizuki
- Department of Otorhinolaryngology, St. Marianna University School of Medicine, Kanagawa, Japan
| | - Yusuke Ito
- Department of Otorhinolaryngology, St. Marianna University School of Medicine, Kanagawa, Japan
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Tian C, Zha D. Sympathetic Nervous System Regulation of Auditory Function. Audiol Neurootol 2021; 27:93-103. [PMID: 34407531 DOI: 10.1159/000517452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 05/26/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The auditory system processes how we hear and understand sounds within the environment. It comprises both peripheral and central structures. Sympathetic nervous system projections are present throughout the auditory system. The function of sympathetic fibers in the cochlea has not been studied extensively due to the limited number of direct projections in the auditory system. Nevertheless, research on adrenergic and noradrenergic regulation of the cochlea and central auditory system is growing. With the rapid development of neuroscience, auditory central regulation is an extant topic of focus in research on hearing. SUMMARY As such, understanding sympathetic nervous system regulation of auditory function is a growing topic of interest. Herein, we review the distribution and putative physiological and pathological roles of sympathetic nervous system projections in hearing. Key Messages: In the peripheral auditory system, the sympathetic nervous system regulates cochlear blood flow, modulates cochlear efferent fibers, affects hair cells, and influences the habenula region. In central auditory pathways, norepinephrine is essential for plasticity in the auditory cortex and affects auditory cortex activity. In pathological states, the sympathetic nervous system is associated with many hearing disorders. The mechanisms and pathways of sympathetic nervous system modulation of auditory function is still valuable for us to research and discuss.
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Affiliation(s)
- Chaoyong Tian
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Dingjun Zha
- Department of Otolaryngology Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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4
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Wung D, Goderie T, van Wier MF, Stam M, Kramer SE. Association of beta blocker use and hearing ability in adults: a cross-sectional study. Int J Audiol 2021; 61:102-107. [PMID: 34057380 DOI: 10.1080/14992027.2021.1915508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVES To investigate the potential association between beta blocker use and hearing ability in adults and to discern whether this effect is dose-dependent. DESIGN Cross-sectional analyses. Multiple linear regression was performed with hearing ability as the dependent variable and beta blocker use as the independent variable. The independent variable was classified into three dose categories for secondary analysis. Adjustments were made for age, gender, educational level, and tobacco smoking status. STUDY SAMPLE 1636 adults, 75 of whom reported being on beta blockers, from the internet-based Netherlands Longitudinal Study on Hearing (NL-SH). RESULTS No significant association was found between beta blocker use and hearing ability in noise. In the adjusted regressions, beta blocker use changed the speech reception threshold in noise (SRT) by -0.04 dB signal-to-noise ratio (SNR) (95%CI [-0.67 to 0.58], p = 0.890). Medium dose beta blocker use changed SRT by -0.42 dB SNR (95%CI [-1.38 to 0.71], p = 0.433), while a high dose changed it by -0.26 dB SNR (95%CI [-1.74 to 1.4], p = 0.767). CONCLUSIONS No evidence was found for beta blocker-induced changes in hearing ability. Future studies on this topic should favour case-control and cohort study designs, while focussing on a hypertensive population to minimise confounding by indication.
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Affiliation(s)
- Deanna Wung
- Ecole des Hautes Etudes en Santé Publique, Rennes, France
| | - Thadé Goderie
- Department of Otolaryngology-Head and Neck Surgery, Ear and Hearing, Amsterdam Public Health Research Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Marieke F van Wier
- Department of Otolaryngology-Head and Neck Surgery, Ear and Hearing, Amsterdam Public Health Research Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Mariska Stam
- Department of Otolaryngology-Head and Neck Surgery, Ear and Hearing, Amsterdam Public Health Research Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,National Health Care Institute, Diemen, The Netherlands
| | - Sophia E Kramer
- Department of Otolaryngology-Head and Neck Surgery, Ear and Hearing, Amsterdam Public Health Research Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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Al-Ghamdi BS, Rohra DK, Abuharb GAI, Alkofide HA, AlRuwaili NS, Shoukri MM, Cahusac PMB. Use of beta blockers is associated with hearing loss. Int J Audiol 2017; 57:213-220. [DOI: 10.1080/14992027.2017.1405162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Bandar Saeed Al-Ghamdi
- Department of Cardiology, Heart Centre, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia,
- Department of Medicine, Alfaisal University, Riyadh, Saudi Arabia,
| | - Dileep Kumar Rohra
- Department of Pharmacology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia,
| | - Gheid Ali Ibrahim Abuharb
- Clinical Audiology, Department of Otolaryngology, Head & Neck Surgery and Communication Sciences, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia,
| | - Hala Abdulrahman Alkofide
- Clinical Audiology, Department of Otolaryngology, Head & Neck Surgery and Communication Sciences, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia,
| | - Nadiah Salem AlRuwaili
- Department of Cardiology, Heart Centre, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia,
| | - Mohamed M. Shoukri
- Department of Cell Biology and the National Biotechnology Centre, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia, and
| | - Peter M. B. Cahusac
- Department of Pharmacology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia,
- Department of Comparative Medicine, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
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Masuda M, Kanzaki S, Minami S, Kikuchi J, Kanzaki J, Sato H, Ogawa K. Correlations of inflammatory biomarkers with the onset and prognosis of idiopathic sudden sensorineural hearing loss. Otol Neurotol 2013; 33:1142-50. [PMID: 22872174 DOI: 10.1097/mao.0b013e3182635417] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS We investigated whether inflammatory biomarkers and stress are involved in the pathophysiology of idiopathic sensorineural hearing loss (ISHL). STUDY DESIGN Individual cohort study. SETTING Two tertiary centers. PATIENTS Forty-three ISHL and 10 non-ISHL patients seen in our ENT departments from 2004 to 2010 within a week from the onset of new symptoms and without steroid administration before visiting our departments. INTERVENTION Multiple audiologic evaluations, blood tests including leukocyte counts, natural killer cell activity (NKCA), interleukin 6 (IL-6), tumor necrosis factor, high-sensitivity CRP (hCRP), and the General Health Questionnaire were used to evaluate the systemic stress and inflammatory response. MAIN OUTCOME MEASURES Correlations between biomarkers and ISHL severity and prognosis were evaluated by statistical analysis. RESULTS In the ISHL patients, a neutrophil count above the reference range was associated with severe hearing loss and poor prognosis, and was accompanied by low NKCA and high IL-6. In the non-ISHL patients, these associations were not present. The abnormal neutrophil count was independent of preexisting vascular diseases. The abnormal counts responded to treatment and decreased into the reference range. CONCLUSION Neutrophil counts above the reference range of a facility will be a useful indicator of poor prognosis of ISHL. Synchronism of different types of NF-κB activation pathways could be required to cause severe ISHL. An NKCA decrease, an acute neutrophil count increase, and an IL-6 increase can induce NF-κB activation in the cochlea and cause severe ISHL. Further epidemiologic surveys should be conducted to evaluate whether stressful life events increase the risk of severe ISHL onset.
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Affiliation(s)
- Masatsugu Masuda
- Department of Otolaryngology, School of Medicine, Keio University, Tokyo, Japan.
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7
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Kanzaki J, Masuda M. Correlation between stress and acute sensorineural hearing loss: stress and sudden deafness. ACTA ACUST UNITED AC 2013. [DOI: 10.4295/audiology.56.137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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8
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Maison SF, Le M, Larsen E, Lee SK, Rosowski JJ, Thomas SA, Liberman MC. Mice lacking adrenergic signaling have normal cochlear responses and normal resistance to acoustic injury but enhanced susceptibility to middle-ear infection. J Assoc Res Otolaryngol 2010; 11:449-61. [PMID: 20503062 DOI: 10.1007/s10162-010-0220-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 05/04/2010] [Indexed: 12/17/2022] Open
Abstract
The vasculature and neurons of the inner ear receive adrenergic innervation from the cervical sympathetic chain, and adrenergic receptors may be expressed by cells of the organ of Corti and stria vascularis, despite a lack of direct sympathetic innervation. To assess the functional role of adrenergic signaling in the auditory periphery, we studied mice with targeted deletion of the gene for dopamine beta-hydroxylase (DBH), which catalyzes the conversion of dopamine to noradrenaline; thus, these mutant mice have no measurable adrenaline or noradrenaline. Dbh (-/-) mice were more susceptible to spontaneous middle-ear infection than their control littermates, consistent with a role for sympathetics in systemic and/or local immune response. At 6-8 weeks of age, cochlear thresholds and suprathreshold responses assessed by auditory brainstem responses and distortion product otoacoustic emissions, as well as light-microscopic morphology, were indistinguishable from controls, if ears with conductive hearing loss were eliminated. Dbh (-/-) mice were no more susceptible to acoustic injury than controls, despite prior reports that sympathectomy reduces noise damage. Dbh (-/-) mice showed enhancement of shock-evoked olivocochlear suppression of cochlear responses, which may arise from the loss of adrenergic inputs to olivocochlear neurons in the brainstem. However, adrenergic modulation of olivocochlear efferents does not mediate the protective effect of contralateral cochlear destruction on ipsilateral response to acoustic overexposure.
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Affiliation(s)
- Stéphane F Maison
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA.
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9
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Stria vascularis and vestibular dark cells: characterisation of main structures responsible for inner-ear homeostasis, and their pathophysiological relations. The Journal of Laryngology & Otology 2008; 123:151-62. [DOI: 10.1017/s0022215108002624] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThe regulation of inner-ear fluid homeostasis, with its parameters volume, concentration, osmolarity and pressure, is the basis for adequate response to stimulation. Many structures are involved in the complex process of inner-ear homeostasis. The stria vascularis and vestibular dark cells are the two main structures responsible for endolymph secretion, and possess many similarities. The characteristics of these structures are the basis for regulation of inner-ear homeostasis, while impaired function is related to various diseases. Their distinct morphology and function are described, and related to current knowledge of associated inner-ear diseases. Further research on the distinct function and regulation of these structures is necessary in order to develop future clinical interventions.
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10
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Wangemann P. Supporting sensory transduction: cochlear fluid homeostasis and the endocochlear potential. J Physiol 2006; 576:11-21. [PMID: 16857713 PMCID: PMC1995626 DOI: 10.1113/jphysiol.2006.112888] [Citation(s) in RCA: 330] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 07/14/2006] [Indexed: 12/13/2022] Open
Abstract
The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endocochlear potential and requires a highly specialized environment that enables and sustains sensory function. Disturbance of cochlear homeostasis is the cause of many forms of hearing loss including the most frequently occurring syndromic and non-syndromic forms of hereditary hearing loss, Pendred syndrome and Cx26-related deafness. The occurrence of these and other monogenetic disorders illustrates that cochlear fluid homeostasis and the generation of the endocochlear potential are poorly secured by functional redundancy. This review summarizes the most prominent aspects of cochlear fluid homeostasis. It covers cochlear fluid composition, the generation of the endocochlear potential, K(+) secretion and cycling and its regulation, the role of gap junctions, mechanisms of acid-base homeostasis, and Ca(2+) transport.
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Affiliation(s)
- Philine Wangemann
- Anatomy & Physiology Department, 205 Coles Hall, Kansas State University, Manhattan, 66506, USA.
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11
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Khan KM, Sarfaraz N, Siddiqui S, Nawaz H. Immunohistochemical localization of G protein betagamma subunits in the lateral wall of the rat cochlea. J Anat 2006; 208:205-18. [PMID: 16441565 PMCID: PMC2100195 DOI: 10.1111/j.1469-7580.2006.00526.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The role of G protein-mediated signal transduction in the production of endolymph, an extracellular fluid of unusual ionic composition, is beginning to be understood. The identity of Galpha subunits in the stria vascularis and the spiral ligament of the lateral wall of the cochlear duct is well established. However, little is known about the presence of betagamma subunits. This study used immunohistochemistry to investigate the distribution of G protein betagamma subunits in the lateral wall of the cochlea. Temporal bones of 6- to 8-week-old rats were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde and processed for embedding in paraffin wax. The dewaxed, midmodiolar sections of the cochlea were incubated with subunit-specific polyclonal antibodies. The results show that the pattern of immunoreactivity varies for the G protein beta1-4 and gamma1-3, 5 and 7 subunits in the stria vascularis and spiral ligament. In the stria vascularis, immunoreactivity was detected for beta2, beta3, beta4, gamma1, gamma2 and gamma7 subunits. All five types of fibrocytes in the spiral ligament exhibited positive staining for gamma2 and gamma7. However, immunoreactivity for beta1-4 subunits was variable. Immunoreactivity for gamma3 and gamma5 subunits was not detected in the lateral cochlear wall. The expression pattern of G protein betagamma subunits in lateral wall provides a basis for interpreting the functions of G protein-coupled receptors in cochlear fluid homeostasis.
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Affiliation(s)
- Khalid M Khan
- Department of Biological & Biomedical Sciences, Faculty of Health Sciences, The Aga Khan University, Karachi, Pakistan.
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12
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Fauser C, Schimanski S, Wangemann P. Localization of beta1-adrenergic receptors in the cochlea and the vestibular labyrinth. J Membr Biol 2005; 201:25-32. [PMID: 15635809 PMCID: PMC2020520 DOI: 10.1007/s00232-004-0703-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Sympathetic activation in a "fight or flight reaction" may put the sensory systems for hearing and balance into a state of heightened alert via beta1-adrenergic receptors (beta1-AR). The aim of the present study was to localize beta1-AR in the gerbil inner ear by confocal immunocytochemistry, to characterize beta1-AR by Western immunoblots, and to identify beta1-AR pharmacologically by measurements of cAMP production. Staining for beta1-AR was found in strial marginal cells, inner and outer hair cells, outer sulcus, and spiral ganglia cells of the cochlea, as well as in dark, transitional and supporting cells of the vestibular labyrinth. Receptors were characterized in microdissected inner ear tissue fractions as 55 kDa non-glycosylated species and as 160 kDa high-mannose-glycosylated complexes. Pharmacological studies using isoproterenol, ICI-118551 and CGP-20712A demonstrated beta1-AR as the predominant adrenergic receptor in stria vascularis and organ of Corti. In conclusion, beta1-AR are present and functional in inner ear epithelial cells that are involved in K+ cycling and auditory transduction, as well as in neuronal cells that are involved in auditory transmission.
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Affiliation(s)
- C Fauser
- Cell Physiology Laboratory, Anatomy & Physiology Department, Kansas State University, Manhattan, KS 66506, USA
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13
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Khan KM, Sarfaraz N, Siddiqui S, Malik ZA, Salim Z. Expression of G protein alpha subunits in the lateral wall of the rat cochlea. J Anat 2003; 202:293-301. [PMID: 12713269 PMCID: PMC1571081 DOI: 10.1046/j.1469-7580.2003.00159.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/17/2002] [Indexed: 11/20/2022] Open
Abstract
Expression of five G protein alpha subunits was investigated in the rat cochlea by reverse transcription-polymerase chain reaction (RT-PCR) in order to understand their role in the cochlear signal transduction mechanisms. Immunohistochemical techniques were employed to study their distribution in the lateral wall of the cochlea. Total RNA was extracted with guanidine thiocyanate from cochleas and brains of 14-21-day-old rats. The extract was treated with DNase to degrade genomic DNA. After RT, the resulting cDNA was amplified by PCR using primers specific for the nucleotide sequences representing alpha subunits of heterotrimeric G proteins. The results indicated that mRNA for all five alpha subunits was expressed in the brain and cochlear samples. For immunohistochemical localization, temporal bones of 6-week-old rats were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde and processed for embedding in paraffin wax. The dewaxed, midmodiolar sections of the cochlea were incubated with subunit-specific polyclonal antibodies. The pattern of immunoreactivity varied for the five G protein alpha subunits studied in the stria vascularis and spiral ligament. The significance of these findings and the role of G protein alpha subunits in cochlear fluid homeostasis are discussed.
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Affiliation(s)
- Khalid M Khan
- Department of Biological & Biomedical Sciences, Faculty of Health Sciences, The Aga Khan University, Karachi, Pakistan.
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14
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Carlin RW, Lee JH, Marcus DC, Schultz BD. Adenosine stimulates anion secretion across cultured and native adult human vas deferens epithelia. Biol Reprod 2003; 68:1027-34. [PMID: 12604657 DOI: 10.1095/biolreprod.102.009381] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Experiments were conducted to determine the responsiveness of human vas deferens epithelial cell monolayers to adenosine and related agonists. Human abdominal vas deferens epithelial cells have been isolated from adult tissues and grown to confluence on permeable supports. All cells exhibit intense ZO-1 and cytokeratin immunoreactivity. Cultured cell monolayers exhibit high electrical resistance with a lumen-negative potential difference and short circuit current (I(sc)) indicative of anion secretion and/or cation absorption. A portion of the basal I(sc) is inhibited by amiloride. Amiloride-sensitive I(sc) is enhanced by exposure to glucocorticoids and is Na(+) dependent, indicating the presence of epithelial sodium channel-mediated Na(+) absorption. Epithelial anion secretion and intracellular generation of cAMP are acutely stimulated by adenosine and the adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine (NECA), with these effects being fully blocked by 8-phenyltheophylline. Adenosine receptors are localized to the apical membrane of the epithelial cells, as basolateral adenosine is without effect. Freshly excised human vas deferens recapitulate observations made on cultured epithelia when evaluated with the self-referencing vibrating probe: amiloride inhibition of basal ion transport, stimulation by adenosine, and inhibition by 8-phenyltheophyline. These results demonstrate that adult human vas deferens epithelium actively transports ions to generate the luminal environment of the deferent duct. Thus, vas deferens epithelium likely plays an active role in male fertility, and interventions that modulate epithelial function might be exploited to treat male-factor infertility or in contraception.
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Affiliation(s)
- Ryan W Carlin
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66502-5802, USA
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Milhaud PG, Pondugula SR, Lee JH, Herzog M, Lehouelleur J, Wangemann P, Sans A, Marcus DC. Chloride secretion by semicircular canal duct epithelium is stimulated via beta 2-adrenergic receptors. Am J Physiol Cell Physiol 2002; 283:C1752-60. [PMID: 12388054 DOI: 10.1152/ajpcell.00283.2002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ductal epithelium of the semicircular canal forms much of the boundary between the K+-rich luminal fluid and the Na+-rich abluminal fluid. We sought to determine whether the net ion flux producing the apical-to-basal short-circuit current (I(sc)) in primary cultures was due to anion secretion and/or cation absorption and under control of receptor agonists. Net fluxes of 22Na, 86Rb, and 36Cl demonstrated a basal-to-apical Cl- secretion that was stimulated by isoproterenol. Isoproterenol and norepinephrine increased I(sc) with an EC50 of 3 and 15 nM, respectively, and isoproterenol increased tissue cAMP of native canals with an EC50 of 5 nM. Agonists for adenosine, histamine, and vasopressin receptors had no effect on I(sc). Isoproterenol stimulation of I(sc) and cAMP was inhibited by ICI-118551 (IC50 = 6 microM for I(sc)) but not by CGP-20712A (1 microM) in primary cultures, and similar results were found in native epithelium. I(sc) was partially inhibited by basolateral Ba2+ (IC50 = 0.27 mM) and ouabain, whereas responses to genistein, glibenclamide, and DIDS did not fully fit the profile for CFTR. Our findings show that the canal epithelium contributes to endolymph homeostasis by secretion of Cl- under beta 2 adrenergic control with cAMP as second messenger, a process that parallels the adrenergic control of K+ secretion by vestibular dark cells. The current work points to one possible etiology of endolymphatic hydrops in Meniere's disease and may provide a basis for intervention.
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Affiliation(s)
- Pierre G Milhaud
- Institut National de la Santé et de la Recherche Médicale Unité 432 Vestibular Neurobiology, Université Montpellier II, 34095 Montpellier, France
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16
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Wangemann P. K(+) cycling and its regulation in the cochlea and the vestibular labyrinth. Audiol Neurootol 2002; 7:199-205. [PMID: 12097719 DOI: 10.1159/000063736] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Potassium (K(+)) plays a very important role in the cochlea. K(+) is the major cation in endolymph and the charge carrier for sensory transduction and the generation of the endocochlear potential. The importance of K(+) handling in the cochlea is marked by the discovery of several forms of hereditary deafness that are due to mutations of K(+) channels. Deafness results from mutations of KCNQ4, a K(+) channel in the sensory hair cells, as well as from mutations of the gap junction proteins GJB2, GJB3 and GJB6 that may facilitate cell-to-cell movements of K(+). Deafness results also from mutations of KCNQ1 or KCNE1, subunits of a K(+) channel that carries K(+) from strial marginal cells and vestibular dark cells into endolymph. Further, deafness results from mutations of KCNJ10, a K(+) channel that generates the endocochlear potential in conjunction with the high K(+) concentration in strial intermediate cells and the low K(+) concentration in the intrastrial fluid spaces. This review details recent advances in the understanding of K(+) transport and its regulation in the cochlea and the vestibular labyrinth.
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Affiliation(s)
- Philine Wangemann
- Cell Physiology Laboratory, Anatomy and Physiology Department, Kansas State University, Manhattan, Kans 66506, USA.
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