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Pan X, Huang C, Peng A, Zhang Z. Immunohistochemical localisation of aquaporin 2 and vasopressin type 2 receptor in the human endolymphatic sac. J Laryngol Otol 2023; 137:1340-1344. [PMID: 36502818 DOI: 10.1017/s0022215122002444] [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] [Indexed: 12/14/2022]
Abstract
OBJECTIVE This study aimed to determine the distribution and subcellular localisation of aquaporin 2 and vasopressin type 2 receptor in the human endolymphatic sac. METHODS Ten samples of human endolymphatic sac were collected during acoustic neurinoma removal using the translabyrinthine approach. Immunohistochemistry and immunofluorescence were performed using aquaporin 2 and vasopressin type 2 receptor monoclonal antibodies. RESULTS Confocal microscopy demonstrated that vasopressin type 2 receptor labelling was expressed in both the apical and basolateral plasma membranes, and in the cytoplasm of the endolymphatic sac epithelium, whereas aquaporin 2 was strongly expressed at the basolateral site of the endolymphatic sac epithelium, in both the intraosseous and extraosseous parts of the endolymphatic sac. CONCLUSION Both aquaporin 2 and vasopressin type 2 receptor were detected in the epithelial cells of the human endolymphatic sac, suggesting that this channel may be involved in inner-ear fluid homeostasis. However, strong basolateral expression of aquaporin 2 in endolymphatic sac epithelium suggested that the function of aquaporin 2 may differ between the endolymphatic sac and kidney.
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Affiliation(s)
- X Pan
- Department of Otolaryngology - Head and Neck Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - C Huang
- Department of Otolaryngology - Head and Neck Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - A Peng
- Department of Otolaryngology - Head and Neck Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Z Zhang
- Department of Otolaryngology - Head and Neck Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
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Calvillo-Robledo A, Ramírez-Farías C, Valdez-Urias F, Huerta-Carreón EP, Quintanar-Stephano A. Arginine vasopressin hormone receptor antagonists in experimental autoimmune encephalomyelitis rodent models: A new approach for human multiple sclerosis treatment. Front Neurosci 2023; 17:1138627. [PMID: 36998727 PMCID: PMC10043225 DOI: 10.3389/fnins.2023.1138627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/27/2023] [Indexed: 03/18/2023] Open
Abstract
Multiple sclerosis (MS) is a chronic demyelinating and neurodegenerative disease that affects the central nervous system. MS is a heterogeneous disorder of multiple factors that are mainly associated with the immune system including the breakdown of the blood-brain and spinal cord barriers induced by T cells, B cells, antigen presenting cells, and immune components such as chemokines and pro-inflammatory cytokines. The incidence of MS has been increasing worldwide recently, and most therapies related to its treatment are associated with the development of several secondary effects, such as headaches, hepatotoxicity, leukopenia, and some types of cancer; therefore, the search for an effective treatment is ongoing. The use of animal models of MS continues to be an important option for extrapolating new treatments. Experimental autoimmune encephalomyelitis (EAE) replicates the several pathophysiological features of MS development and clinical signs, to obtain a potential treatment for MS in humans and improve the disease prognosis. Currently, the exploration of neuro-immune-endocrine interactions represents a highlight of interest in the treatment of immune disorders. The arginine vasopressin hormone (AVP) is involved in the increase in blood−brain barrier permeability, inducing the development and aggressiveness of the disease in the EAE model, whereas its deficiency improves the clinical signs of the disease. Therefore, this present review discussed on the use of conivaptan a blocker of AVP receptors type 1a and type 2 (V1a and V2 AVP) in the modulation of immune response without completely depleting its activity, minimizing the adverse effects associated with the conventional therapies becoming a potential therapeutic target in the treatment of patients with multiple sclerosis.
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A Perspective for Ménière’s Disease: In Silico Investigations of Dexamethasone as a Direct Modulator of AQP2. Biomolecules 2022; 12:biom12040511. [PMID: 35454100 PMCID: PMC9028334 DOI: 10.3390/biom12040511] [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: 03/03/2022] [Revised: 03/21/2022] [Accepted: 03/24/2022] [Indexed: 12/04/2022] Open
Abstract
Ménière’s disease is a chronic illness characterized by intermittent episodes of vertigo associated with fluctuating sensorineural hearing loss, tinnitus and aural pressure. This pathology strongly correlates with a dilatation of the fluid compartment of the endolymph, so-called hydrops. Dexamethasone is one of the therapeutic approaches recommended when conventional antivertigo treatments have failed. Several mechanisms of actions have been hypothesized for the mode of action of dexamethasone, such as the anti-inflammatory effect or as a regulator of inner ear water homeostasis. However, none of them have been experimentally confirmed so far. Aquaporins (AQPs) are transmembrane water channels and are hence central in the regulation of transcellular water fluxes. In the present study, we investigated the hypothesis that dexamethasone could impact water fluxes in the inner ear by targeting AQP2. We addressed this question through molecular dynamics simulations approaches and managed to demonstrate a direct interaction between AQP2 and dexamethasone and its significant impact on the channel water permeability. Through compartmentalization of sodium and potassium ions, a significant effect of Na+ upon AQP2 water permeability was highlighted as well. The molecular mechanisms involved in dexamethasone binding and in its regulatory action upon AQP2 function are described.
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Kunelskaya NL, Kryukov AI, Baibakova EV, Yanyushkina ES, Larionova EV. [Labyrinth hydrops and its diagnosis]. Vestn Otorinolaringol 2020; 85:83-87. [PMID: 33140941 DOI: 10.17116/otorino20208505183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The article deals with the basic theories of maze and labyrinth hydrops, which are often used in clinical practice for its diagnosis according to the world literature. Tonal threshold, suprathreshold audiometry, broadband thympanometry, ultrasound tests, test for determination of lateralization of loud sounds, dehydration test, extra-timbanical electrocochleography, method of registration of evoked vestibular myogenic potentials, study of vestibular function (video pulse test, caloric sample), CT of temporal bones with gadolinium, MRI, and other methods are considered. None of these study methods gives an accurate confirmation of the presence of maze hydrops. Only taking into account the history, complaints of the patient, clinical manifestations of the disease and a comprehensive evaluation of the results of all the above methods of study can we speak with confidence about hydropse.
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Affiliation(s)
- N L Kunelskaya
- L.I. Sverzhevsky Scientific Research Clinical Institute of Otorhinolaryngology, Moscow, Russia.,N.I. Pirogov Russian National Research Medical University, Moscow, Russia
| | - A I Kryukov
- L.I. Sverzhevsky Scientific Research Clinical Institute of Otorhinolaryngology, Moscow, Russia.,N.I. Pirogov Russian National Research Medical University, Moscow, Russia
| | - E V Baibakova
- L.I. Sverzhevsky Scientific Research Clinical Institute of Otorhinolaryngology, Moscow, Russia
| | - E S Yanyushkina
- L.I. Sverzhevsky Scientific Research Clinical Institute of Otorhinolaryngology, Moscow, Russia
| | - E V Larionova
- L.I. Sverzhevsky Scientific Research Clinical Institute of Otorhinolaryngology, Moscow, Russia
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A Micro-CT and Synchrotron Imaging Study of the Human Endolymphatic Duct with Special Reference to Endolymph Outflow and Meniere's Disease. Sci Rep 2020; 10:8295. [PMID: 32427861 PMCID: PMC7237694 DOI: 10.1038/s41598-020-65110-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/27/2020] [Indexed: 12/22/2022] Open
Abstract
Meniere’s disease remains enigmatic, and has no treatment with sufficient evidence. The characteristic histopathological finding is endolymphatic hydrops, suggesting either an overproduction or decreased reabsorption of endolymph in the human inner ear. This study presents the first analysis of the vascular plexus around the human endolymphatic duct using micro computed tomography and coherent synchrotron radiation with phase contrast imaging. Using a software program, data were processed by volume-rendering with scalar opacity mapping to create transparent three-dimensional reconstructions. A rich vascular plexus was discovered around the endolymphatic duct that drained into collecting channels, linked to the vestibular venous outflow system. This network is believed to make up the principal route for endolymph outflow, and its associated malfunction may result in endolymphatic hydrops and Meniere’s disease.
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Xu LH, Yang Y, Liu HX, Xiao SF, Qiu WX, Wang JX, Zhao CC, Gui YH, Liu GZ, Peng B, Li X, Wang GH, Zhou X, Jiang ZL. Inner Ear Arginine Vasopressin-Vasopressin Receptor 2-Aquaporin 2 Signaling Pathway Is Involved in the Induction of Motion Sickness. J Pharmacol Exp Ther 2020; 373:248-260. [PMID: 32165443 DOI: 10.1124/jpet.119.264390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/24/2020] [Indexed: 11/22/2022] Open
Abstract
It has been identified that arginine vasopressin (AVP), vasopressin receptor 2(V2R), and the aquaporin 2 (AQP2) signaling pathway in the inner ear play important roles in hearing and balance functions through regulating the endolymph equilibrium; however, the contributions of this signaling pathway to the development of motion sickness are unclear. The present study was designed to investigate whether the activation of the AVP-V2R-AQP2 signaling pathway in the inner ear is involved in the induction of motion sickness and whether mozavaptan, a V2R antagonist, could reduce motion sickness. We found that both rotatory stimulus and intraperitoneal AVP injection induced conditioned taste aversion (a confirmed behavioral index for motion sickness) in rats and activated the AVP-V2R-AQP2 signaling pathway with a responsive V2R downregulation in the inner ears, and AVP perfusion in cultured epithelial cells from rat endolymphatic sacs induced similar changes in this pathway signaling. Vestibular training, V2R antagonist mozavaptan, or PKA inhibitor H89 blunted these changes in the V2R-AQP2 pathway signaling while reducing rotatory stimulus- or DDAVP (a V2R agonist)-induced motion sickness in rats and dogs. Therefore, our results suggest that activation of the inner ear AVP-V2R-AQP2 signaling pathway is potentially involved in the development of motion sickness; thus, mozavaptan targeting AVP V2Rs in the inner ear may provide us with a new application option to reduce motion sickness. SIGNIFICANCE STATEMENT: Motion sickness affects many people traveling or working. In the present study our results showed that activation of the inner ear arginine vasopressin-vaspopressin receptor 2 (V2R)-aquaporin 2 signaling pathway was potentially involved in the development of motion sickness and that blocking V2R with mozavaptan, a V2R antagonist, was much more effective in reducing motion sickness in both rat and dog; therefore, we demonstrated a new mechanism to underlie motion sickness and a new candidate drug to reduce motion sickness.
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Affiliation(s)
- Li-Hua Xu
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Yao Yang
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Hong-Xia Liu
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Shui-Feng Xiao
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Wen-Xia Qiu
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Jin-Xing Wang
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Chen-Chen Zhao
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Yuan-Hong Gui
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Gui-Zhu Liu
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Bin Peng
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Xia Li
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Guo-Hua Wang
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Xin Zhou
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Zheng-Lin Jiang
- Department of Neurophysiology and Neuropharmacology, Institute of Special Environmental Medicine, Institute of Nautical Medicine and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
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Dong SH, Kim SS, Kim SH, Yeo SG. Expression of aquaporins in inner ear disease. Laryngoscope 2019; 130:1532-1539. [PMID: 31593306 DOI: 10.1002/lary.28334] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 09/05/2019] [Accepted: 09/10/2019] [Indexed: 12/22/2022]
Abstract
The inner ear is responsible for hearing and balance and consists of a membranous labyrinth within a bony labyrinth. The balance structure is divided into the otolith organ that recognizes linear acceleration and the semicircular canal that is responsible for rotational movement. The cochlea is the hearing organ. The external and middle ear are covered with skin and mucosa, respectively, and the space is filled with air, whereas the inner ear is composed of endolymph and perilymph. The inner ear is a fluid-filled sensory organ composed of hair cells with cilia on the upper part of the cells that convert changes in sound energy and balance into electric energy through the hair cells to transmit signals to the auditory nerve through synapses. Aquaporins (AQPs) are a family of transmembrane proteins present in all species that can be roughly divided into three subfamilies according to structure and function: 1) classical AQP, 2) aquaglyceroporin, and 3) superaquaporin. Currently, the subfamily of mammalian species is known to include 13 AQP members (AQP0-AQP12). AQPs have a variety of functions depending on their structure and are related to inner ear diseases such as Meniere's disease, sensorineural hearing loss, and presbycusis. Additional studies on the relationship between the inner ear and AQPs may be helpful in the diagnosis and treatment of inner ear disease. Laryngoscope, 130:1532-1539, 2020.
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Affiliation(s)
- Sung Hwa Dong
- Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School, Kyung Hee University, Seoul, South Korea
| | - Sung Su Kim
- Medical Research Center for Bioreaction to Reactive Oxygen Species and Biomedical Science Institute, School of Medicine, Graduate School, Kyung Hee University, Seoul, South Korea
| | - Sang Hoon Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School, Kyung Hee University, Seoul, South Korea
| | - Seung Geun Yeo
- Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School, Kyung Hee University, Seoul, South Korea.,Medical Research Center for Bioreaction to Reactive Oxygen Species and Biomedical Science Institute, School of Medicine, Graduate School, Kyung Hee University, Seoul, South Korea
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JIANG LY, CHEN XX, HE JJ, CHEN HD. Effects of electroacupuncture on cochlear morphology and expression of aquaporins in rats with AVP-induced endolymphatic hydrops. WORLD JOURNAL OF ACUPUNCTURE-MOXIBUSTION 2019. [DOI: 10.1016/j.wjam.2019.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Murofushi T, Tsubota M, Kitao K, Yoshimura E. Simultaneous Presentation of Definite Vestibular Migraine and Definite Ménière's Disease: Overlapping Syndrome of Two Diseases. Front Neurol 2018; 9:749. [PMID: 30250448 PMCID: PMC6139324 DOI: 10.3389/fneur.2018.00749] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 08/17/2018] [Indexed: 01/01/2023] Open
Abstract
Objectives: To review the clinical records of patients that exhibited the clinical features of both vestibular migraine (VM) and Ménière's disease (MD) during each episodic vertigo attack and to discuss the possible pathophysiology of such combination of symptoms. Subjects: Ten patients that were selected according to criteria based on a combination of the diagnostic criteria for definite MD and VM (9 females and one male, age: 22–54 years) were enrolled. They were required to show features of both diseases in each vertigo attack. Methods: The patients' medical histories and pure-tone audiometry, cervical vestibular evoked myogenic potential (cVEMP), video head-impulse test (vHIT), and caloric test results were examined. cVEMP was recorded using 500 and 1,000 Hz short tone bursts (125dBSPL, air-conducted), 500 Hz-1,000 Hz cVEMP slope, an index of endolymphatic hydrops in the saccule was calculated using normalized amplitudes of p13-n23. For performing vHIT, each subject was seated 1.5 m in front of a target and asked to keep watching it as their head was passively rotated by the examiner. Their eye movements were evaluated using video-oculography while their head movements were recorded using inertial sensors. Results: The patients were predominantly female. On average, the onset of migrainous headaches occurred 9 years earlier than the onset of vertigo attacks. All of the patients but one had migraines with auras. Five of the 10 patients had a family history of vertigo attacks accompanied by both migrainous and auditory symptoms. The patients mainly displayed hearing loss at low frequencies. Nine patients exhibited 500–1,000 Hz cVEMP slope < −19.9, which was suggestive of endolymphatic hydrops. None of the patients who underwent vHIT showed abnormal canal function. One patient showed unilaterally decreased caloric responses. Conclusions: These patients presented with simultaneous MD and VM signs/symptoms might be referred to “VM/MD overlapping syndrome (VM/MD-OS)” as a new clinical syndrome.
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Affiliation(s)
- Toshihisa Murofushi
- Department of Otolaryngology, Teikyo University School of Medicine Mizonokuchi Hospital, Kawasaki, Japan
| | - Masahito Tsubota
- Department of Otolaryngology, Teikyo University School of Medicine Mizonokuchi Hospital, Kawasaki, Japan
| | - Kyoko Kitao
- Department of Otolaryngology, Teikyo University School of Medicine Mizonokuchi Hospital, Kawasaki, Japan
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Asmar MH, Gaboury L, Saliba I. Ménière’s Disease Pathophysiology: Endolymphatic Sac Immunohistochemical Study of Aquaporin-2, V2R Vasopressin Receptor, NKCC2, and TRPV4. Otolaryngol Head Neck Surg 2018; 158:721-728. [DOI: 10.1177/0194599818756829] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Objectives Endolymphatic sac (ELS) pathophysiology in Ménière’s disease (MD) remains poorly understood. We identified from the literature a group of proteins expressed on the ELS and involved in endolymph volume regulation: aquaporin-2 (AQP2), vasopressin receptor V2R, sodium potassium chloride cotransporter 2 (NKCC2), and transient receptor potential cation channel V4 (TRPV4). Our objective was to determine whether their ELS expression was altered in MD, to better understand the pathophysiology of endolymphatic hydrops. Study Design Prospective case-control study. Setting Tertiary care center. Subjects Twenty-four patients with definite MD undergoing endolymphatic duct blockage surgery were recruited, as well as 23 controls with no history of MD undergoing surgery for vestibular schwannoma (VS). Methods ELS biopsies and blood samples for plasma arginine vasopressin (AVP) were obtained. Immunohistochemistry for AQP2, V2R, NKCC2, and TRPV4 was performed. Slides were scanned digitally for highly sensitive pixel density analysis by specialized software (VIS; Visiopharm). Results Global scores generated by the software represent total and relative protein expression density of 3 staining intensity levels, exclusively on ELS epithelium. AQP2 expression density was significantly elevated in MD compared to VS ( P = .003). There was no significant difference in plasma AVP, V2R, NKCC2, and TRPV4 expression. Conclusion This original study evaluates simultaneous in situ expression of AQP2, V2R, NKCC2, and TRPV4 on the human ELS in MD, with a control group. Our results show only AQP2 upregulation on the ELS of patients with MD. We suggest a constitutively increased expression of AQP2 in MD, independent of its regulatory axis (AVP-V2R). Acquired regulator sequence mutations could support this model.
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Affiliation(s)
- Marc-Henri Asmar
- University of Montreal Hospital Centre Research Centre (CRCHUM), Montreal, QC, Canada
| | - Louis Gaboury
- University of Montreal Hospital Centre Research Centre (CRCHUM), Montreal, QC, Canada
- Department of Pathology and Cell Biology, University of Montreal Hospital Centre (CHUM), Montreal, QC, Canada
| | - Issam Saliba
- University of Montreal Hospital Centre Research Centre (CRCHUM), Montreal, QC, Canada
- Division of Otolaryngology–Head & Neck Surgery, University of Montreal Hospital Centre (CHUM), Montreal, QC, Canada
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Abstract
HYPOTHESIS A review of the most recent literature will provide clinicians with an update of secondary endolymphatic hydrops, aiding in diagnosis and treatment of affected patients. BACKGROUND Secondary endolymphatic hydrops is a pathologic finding of the inner ear resulting in episodic vertigo and intermittent hearing loss. It is a finding for which extensive research is being performed. METHODS A review of the most recent literature on secondary endolymphatic hydrops was performed using PubMed literature search. RESULTS Recent investigation of secondary endolymphatic hydrops has brought attention to traumatic and inflammatory insults as causes for secondary endolymphatic hydrops. Such etiologies, including postsurgical effects of cochlear implantation and endolymphatic sac ablation; otosclerosis and its operative intervention(s); acoustic and mechanical trauma; medications; and systemic inflammatory processes, have been determined as causes of secondary lymphatic hydrops. Histopathological slides for many of the etiologies of secondary endolymphatic hydrops are presented. CONCLUSION Through an understanding of the pathophysiology and etiologies of secondary endolymphatic hydrops, clinicians will gain a better understanding of this complex disease process, which will aid in treatment of patients with this disease process.
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Affiliation(s)
- Ashley P. O’Connell Ferster
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, USA
| | - Sebahattin Cureoglu
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota, USA
| | - Nevra Keskin
- Department of Internal Medicine of Ankara University, Ankara, Turkey
- Department of Otolaryngology, Otopathology Laboratory, University of Minnesota, Minneapolis, USA
| | | | - Huseyin Isildak
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, USA
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12
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Runggaldier D, Pradas LG, Neckel PH, Mack AF, Hirt B, Gleiser C. Claudin expression in the rat endolymphatic duct and sac - first insights into regulation of the paracellular barrier by vasopressin. Sci Rep 2017; 7:45482. [PMID: 28374851 PMCID: PMC5379655 DOI: 10.1038/srep45482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/28/2017] [Indexed: 12/13/2022] Open
Abstract
Hearing and balance functions of the inner ear rely on the homeostasis of the endolymphatic fluid. When disturbed, pathologic endolymphatic hydrops evolves as observed in Menière’s disease. The molecular basis of inner ear fluid regulation across the endolymphatic epithelium is largely unknown. In this study we identified the specific expression of the tight junction (TJ) molecules Claudin 3, 4, 6, 7, 8, 10, and 16 in epithelial preparations of the rat inner ear endolymphatic duct (ED) and endolymphatic sac (ES) by high-throughput qPCR and immunofluorescence confocal microscopy. Further we showed that Claudin 4 in the ES is a target of arginine-vasopressin (AVP), a hormone elevated in Menière’s disease. Moreover, our transmission-electron microscopy (TEM) analysis revealed that the TJs of the ED were shallow and shorter compared to the TJ of the ES indicating facilitation of a paracellular fluid transport across the ED epithelium. The significant differences in the subcellular localization of the barrier-forming protein Claudin 3 between the ED and ES epithelium further support the TEM observations. Our results indicate a high relevance of Claudin 3 and Claudin 4 as important paracellular barrier molecules in the ED and ES epithelium with potential involvement in the pathophysiology of Menière’s disease.
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Affiliation(s)
- Daniel Runggaldier
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Lidia Garcia Pradas
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Peter H Neckel
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Corinna Gleiser
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
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Beitz E, Golldack A, Rothert M, von Bülow J. Challenges and achievements in the therapeutic modulation of aquaporin functionality. Pharmacol Ther 2015; 155:22-35. [PMID: 26277280 DOI: 10.1016/j.pharmthera.2015.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aquaporin (AQP) water and solute channels have basic physiological functions throughout the human body. AQP-facilitated water permeability across cell membranes is required for rapid reabsorption of water from pre-urine in the kidneys and for sustained near isosmolar water fluxes e.g. in the brain, eyes, inner ear, and lungs. Cellular water permeability is further connected to cell motility. AQPs of the aquaglyceroporin subfamily are necessary for lipid degradation in adipocytes and glycerol uptake into the liver, as well as for skin moistening. Modulation of AQP function is desirable in several pathophysiological situations, such as nephrogenic diabetes insipidus, Sjögren's syndrome, Menière's disease, heart failure, or tumors to name a few. Attempts to design or to find effective small molecule AQP inhibitors have yielded only a few hits. Challenges reside in the high copy number of AQP proteins in the cell membranes, and spatial restrictions in the protein structure. This review gives an overview on selected physiological and pathophysiological conditions in which modulation of AQP functions appears beneficial and discusses first achievements in the search of drug-like AQP inhibitors.
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Affiliation(s)
- Eric Beitz
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany.
| | - André Golldack
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Monja Rothert
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Julia von Bülow
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
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Vasopressin induces endolymphatic hydrops in mouse inner ear, as evaluated with repeated 9.4 T MRI. Hear Res 2015; 330:119-24. [PMID: 26048336 DOI: 10.1016/j.heares.2015.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/09/2015] [Accepted: 05/25/2015] [Indexed: 11/24/2022]
Abstract
From histopathological specimens, endolymphatic hydrops has been demonstrated in association with inner ear disorders. Recent studies have observed findings suggestive of hydrops using MRI in humans. Previous studies suggest that vasopressin may play a critical role in endolymph homeostasis and may be involved in the development of Ménière's disease. In this study we evaluate the effect of vasopressin administration in vivo in longitudinal studies using two mouse strains. High resolution MRI at 9.4 T in combination with intraperitoneally delivered Gadolinium contrast, was performed before and after chronic subcutaneous administration of vasopressin via mini-osmotic pumps in the same mouse. A development of endolymphatic hydrops over time could be demonstrated in C57BL6 mice (5 mice, 2 and 4 weeks of administration) as well as in CBA/J mice (4 mice, 2 weeks of administration; 6 mice, 3 and 4 weeks of administration). In most C57BL6 mice hydrops developed first after more than 2 weeks while CBA/J mice had an earlier response. These results may suggest an in vivo model for studying endolymphatic hydrops and corroborates the future use of MRI as a tool in the diagnosis and treatment of inner ear diseases, such as Ménière's disease. MRI may also be developed as a critical tool in evaluating inner ear homeostasis in genetically modified mice, to augment the understanding of human disease.
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Naganuma H, Kawahara K, Tokumasu K, Satoh R, Okamoto M. Effects of arginine vasopressin on auditory brainstem response and cochlear morphology in rats. Auris Nasus Larynx 2014; 41:249-54. [DOI: 10.1016/j.anl.2013.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 12/01/2013] [Accepted: 12/09/2013] [Indexed: 11/27/2022]
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Juul KV, Bichet DG, Nielsen S, Nørgaard JP. The physiological and pathophysiological functions of renal and extrarenal vasopressin V2 receptors. Am J Physiol Renal Physiol 2014; 306:F931-40. [PMID: 24598801 DOI: 10.1152/ajprenal.00604.2013] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The arginine vasopressin (AVP) type 2 receptor (V2R) is unique among AVP receptor subtypes in signaling through cAMP. Its key function is in the kidneys, facilitating the urine concentrating mechanism through the AVP/V2 type receptor/aquaporin 2 system in the medullary and cortical collecting ducts. Recent clinical and research observations strongly support the existence of an extrarenal V2R. The clinical importance of the extrarenal V2R spans widely from stimulation of coagulation factor in the endothelium to as yet untested potential therapeutic targets. These include V2R-regulated membranous fluid turnover in the inner ear, V2R-regulated mitogensis and apoptosis in certain tumor tissues, and numerous other cell types where the physiological role of V2Rs still requires further research. Here, we review current evidence on the physiological and pathophysiological functions of renal and extrarenal V2Rs. These functions of V2R are important, not only in rare diseases with loss or gain of function of V2R but also in relation to the recent use of nonpeptide V2R antagonists to treat hyponatremia and possibly retard the growth of cysts and development of renal failure in autosomal dominant polycystic kidney disease. The main functions of V2R in principal cells of the collecting duct are water, salt, and urea transport by modifying the trafficking of aquaporin 2, epithelial Na(+) channels, and urea transporters and vasodilation and stimulation of coagulation factor properties, mainly seen with pharmacological doses of 1-desamino-8-D-AVP. The AVPR2 gene is located on the X chromosome, in a region with high probability of escape from inactivation; this may lead to phenotypic sex differences, with females expressing higher levels of transcript than males.
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Affiliation(s)
- Kristian Vinter Juul
- Medical Science Urology, Ferring Pharmaceuticals, 11 Kay Fiskers Plads, Copenhagen S DK-2300, Denmark.
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Abstract
Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen aquaporins have been characterized. They are distributed wildly in specific cell types in multiple organs and tissues. Each AQP channel consists of six membrane-spanning alpha-helices that have a central water-transporting pore. Four AQP monomers assemble to form tetramers, which are the functional units in the membrane. Some of AQPs also transport urea, glycerol, ammonia, hydrogen peroxide, and gas molecules. AQP-mediated osmotic water transport across epithelial plasma membranes facilitates transcellular fluid transport and thus water reabsorption. AQP-mediated urea and glycerol transport is involved in energy metabolism and epidermal hydration. AQP-mediated CO2 and NH3 transport across membrane maintains intracellular acid-base homeostasis. AQPs are also involved in the pathophysiology of a wide range of human diseases (including water disbalance in kidney and brain, neuroinflammatory disease, obesity, and cancer). Further work is required to determine whether aquaporins are viable therapeutic targets or reliable diagnostic and prognostic biomarkers.
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Water channel proteins in the inner ear and their link to hearing impairment and deafness. Mol Aspects Med 2012; 33:612-37. [DOI: 10.1016/j.mam.2012.06.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/11/2012] [Accepted: 06/17/2012] [Indexed: 11/24/2022]
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Takumida M, Kakigi A, Egami N, Nishioka R, Anniko M. Localization of aquaporins 1, 2, and 3 and vasopressin type 2 receptor in the mouse inner ear. Acta Otolaryngol 2012; 132:807-13. [PMID: 22768909 DOI: 10.3109/00016489.2012.662718] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION It is suggested that aquaporins (AQPs) 1, 2, and 3, and vasopressin type 2 receptors (V2Rs) in the fluid transporting cells, such as stria vascularis, vestibular dark and transitional cells, and endolymphatic sac epithelial cells, have an important role in fluid transport in the inner ear, while those in the sensory and ganglion cells may play a functional role in the sensory cell transduction system. OBJECTIVE To analyze expression of AQP1, AQP2, and AQP3 as well as V2Rs in the normal mouse inner ear. METHODS CBA/J mice were used in this study. Localization of AQP1, AQP2, AQP3, and V2Rs in the inner ear, i.e. cochlea, vestibular end organs, and endolymphatic sac, was investigated by immunohistochemistry. RESULTS The results show that AQP1, AQP2, AQP3, and V2Rs are abundantly distributed in many inner ear structures, i.e. stria vascularis, inner and outer hair cells, spiral ganglion cells, vestibular sensory and ganglion cells, vestibular dark and transitional cells, and the endolymphatic sac.
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Affiliation(s)
- Masaya Takumida
- Department of Otolaryngology, Hiroshima University Hospital, Japan.
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Hirt B, Gleiser C, Eckhard A, Mack A, Müller M, Wolburg H, Löwenheim H. All functional aquaporin-4 isoforms are expressed in the rat cochlea and contribute to the formation of orthogonal arrays of particles. Neuroscience 2011; 189:79-92. [DOI: 10.1016/j.neuroscience.2011.05.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 05/13/2011] [Accepted: 05/14/2011] [Indexed: 11/25/2022]
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Salt AN, Plontke SK. Endolymphatic hydrops: pathophysiology and experimental models. Otolaryngol Clin North Am 2010; 43:971-83. [PMID: 20713237 DOI: 10.1016/j.otc.2010.05.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is well established that endolymphatic hydrops plays a role in Ménière disease, even though the precise role is not fully understood and the presence of hydrops in the ear does not always result in symptoms of the disease. It nevertheless follows that a scientific understanding of how hydrops arises, how it affects the function of the ear, and how it can be manipulated or reversed could contribute to the development of effective treatments for the disease. Measurements in animal models in which endolymphatic hydrops has been induced have given numerous insights into the relationships between hydrops and other pathologic and electrophysiological changes, and how these changes influence the function of the ear. The prominent role of the endolymphatic sac in endolymph volume regulation, and the cascade of histopathological and electrophysiological changes that are associated with chronic endolymphatic hydrops, have now been established. An increasing number of models are now available that allow specific aspects of the interrelationships to be studied. The yclical nature of Ménière symptoms gives hope that treatments can be developed to maintain the ear in permanent state of remission, possibly by controlling endolymphatic hydrops, thereby avoiding the rogressive damage and secondary pathologic changes that may also contribute to the patient's symptoms.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Avenue, St Louis, MO 63110, USA.
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Holt NF, Haspel KL. Vasopressin: A Review of Therapeutic Applications. J Cardiothorac Vasc Anesth 2010; 24:330-47. [DOI: 10.1053/j.jvca.2009.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Indexed: 01/03/2023]
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Nishioka R, Takeda T, Kakigi A, Okada T, Takebayashi S, Taguchi D, Nishimura M, Hyodo M. Expression of aquaporins and vasopressin type 2 receptor in the stria vascularis of the cochlea. Hear Res 2010; 260:11-9. [DOI: 10.1016/j.heares.2009.09.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 09/21/2009] [Accepted: 09/23/2009] [Indexed: 10/20/2022]
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Marshall AF, Jewells VL, Kranz P, Lee YZ, Lin W, Zdanski CJ. Magnetic resonance imaging of guinea pig cochlea after vasopressin-induced or surgically induced endolymphatic hydrops. Otolaryngol Head Neck Surg 2010; 142:260-5. [DOI: 10.1016/j.otohns.2009.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 10/01/2009] [Accepted: 10/02/2009] [Indexed: 10/19/2022]
Abstract
Objective: To investigate the ability to detect the in vivo cochlear changes associated with vasopressin-induced and surgically induced endolymphatic hydrops using MRI at 3 tesla (T). Study Design: Prospective, animal model. Setting: Animal laboratory. Subjects and Methods: In group 1, five guinea pigs underwent post–gadolinium temporal bone MRI before and after seven and 14 days of chronic systemic administration of vasopressin by osmotic pump. In group 2, five guinea pigs underwent temporal bone MRI eight weeks after unilateral surgical ablation of the endolymphatic sac. Three-tesla high-resolution T1-weighted sequences were acquired pre- and postcontrast administration. Region of interest signal intensities of the perilymph and endolymph were analyzed manually. Quantitative evaluation of hydrops was measured histologically. Results: Gadolinium preferentially concentrated in the perilymph, allowing for distinction of cochlear compartments on 3.0-T MRI. The T1-weighted contrast MRI of vasopressin-induced hydropic cochlea showed significant increases in signal intensity of the endolymph and perilymph. Surgically induced unilateral hydropic cochlea also showed increased signal intensity, compared with the control cochlea of the same animal, but less of an increase than the vasopressin group. The histological degree of hydrops induced in the vasopressin group was comparable to previous studies. Conclusions: In vivo postcontrast MRI of the inner ear demonstrated cochlear changes associated with chronic systemic administration of vasopressin and surgical ablation of the endolymphatic sac. Understanding the MRI appearance of endolymphatic hydrops induced by various methods contributes to the future use of MRI as a possible tool in the diagnosis and treatment of Ménière's disease.
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Affiliation(s)
- Allen F. Marshall
- Department of Otolaryngology–Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Valerie L. Jewells
- Department of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Peter Kranz
- Department of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Yeuh Z. Lee
- Department of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Weili Lin
- Department of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Carlton J. Zdanski
- Department of Otolaryngology–Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, NC
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Nishimura M, Kakigi A, Takeda T, Okada T, Doi K. Time course changes of vasopressin-induced enlargement of the rat intrastrial space and the effects of a vasopressin type 2 antagonist. Acta Otolaryngol 2009; 129:709-15. [PMID: 18836965 DOI: 10.1080/00016480802419115] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
CONCLUSION The intrastrial space was enlarged remarkably at 20 min after vasopressin (VP) injection, and this enlargement of the intrastrial space was reduced by administration of OPC-31260 before VP injection. These results suggest that VP increases the influx of water from the perlymph to the basal cells via aquaporin (AQP) 2 and causes the formation of endolymphatic hydrops. OBJECTIVES To investigate a time course of changes of the stria vascularis after VP injection and the influence of OPC-31260 on experimentally induced enlargement of the intrastrial space caused by VP injection. MATERIALS AND METHODS In the time course study, Wistar rats were injected with 50 microg/kg of VP subcutaneously. The stria vascularis specimens were harvested at 10, 20, 30, and 60 min after VP injection. For OPC-31260 administration, animals were administered 100 mg/kg of OPC-31260 orally 1 h before receiving 50 microg/kg of VP subcutaneously. The specimens were harvested 20 min after VP injection. These specimens were observed using transmission electron microscopy. RESULTS In the time course study, the incidence of intrastrial space enlargement was 50%, 100%, 25%, and 0% for 10, 20, 30, and 60 min, respectively. In the study with OPC-31260 administration, the stria vascularis showed no morphological changes.
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Abstract
The homeostasis of water in the inner ear is essential for maintaining function of hearing and equilibrium. Since the discovery of aquaporin water channels, it has become clear that these channels play a crucial role in inner ear fluid homeostasis. Indeed, proteins or mRNAs of AQP1, AQP2, AQP3, AQP4, AQP5, AQP6, AQP7 and AQP9 are expressed in the inner ear. Many of them are expressed mainly in the stria vascularis and the endolymphatic sac, which are the main sites of secretion and/or absorption of endolymph. Vasopressin type2 receptor is also expressed there. Water homeostasis of the inner ear is regulated in part via the arginine vasopressin-AQP2 system in the same fashion as in the kidney, and endolymphatic hydrops, a morphological characteristic of Meniere's disease, is thought to be caused by mal-regulation of this system. Therefore, aquaporins appear to be important for the development of novel drug therapies for Meniere's disease and related disorders.
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Les aquaporines présentes dans le rein. Nephrol Ther 2008; 4:562-7. [DOI: 10.1016/j.nephro.2008.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Revised: 03/28/2008] [Accepted: 03/29/2008] [Indexed: 11/15/2022]
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Taguchi D, Takeda T, Kakigi A, Okada T, Nishioka R, Kitano H. Expression and immunolocalization of aquaporin-6 (Aqp6) in the rat inner ear. Acta Otolaryngol 2008; 128:832-40. [PMID: 18607959 DOI: 10.1080/00016480701765691] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
CONCLUSION Since aquaporin-6 (Aqp6) protein was located in the membrane of intracellular vesicles of the stria vascularis, endolymphatic sac, and vestibule, Aqp6 might be involved in some distinct physiological function of acid-base metabolism and water balance in endolymphatic fluid homeostasis. However, its lack of expression on the plasma membrane indicates that Aqp6 does not have a direct role in water flux via the plasma membrane. OBJECTIVE To evaluate the expression and immunolocalization of Aqp6 in the rat inner ear. MATERIALS AND METHODS Wistar rats were used. Aqp6 mRNA expression in the rat inner ear was investigated in the vestibulum as well as in the cochlea and endolymphatic sac using the reverse transcription-polymerase chain reaction (RT-PCR) method, and detailed immunolocalization of Aqp6 in the rat inner ear was investigated using immunohistochemical methods including immunofluorescence microscopy and immunoelectron microscopy. RESULTS We obtained novel data showing that not just Aqp6 mRNA but also Aqp6 protein is expressed in the cochlea, endolymphatic sac, and vestibule. Immunoelectron microscopic studies revealed that the immunolabelled gold was diffusely seen in the intracellular area of the stria vascularis, endolymphatic sac, and vestibule, but never in the plasma membranes.
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Kakigi A, Nishimura M, Takeda T, Taguchi D, Nishioka R. Expression of aquaporin1, 3, and 4, NKCC1, and NKCC2 in the human endolymphatic sac. Auris Nasus Larynx 2008; 36:135-9. [PMID: 18606512 DOI: 10.1016/j.anl.2008.04.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 03/21/2008] [Accepted: 04/13/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To locate aquaporin (AQP) 1, 3, and 4, Na-K-2Cl cotransporter (NKCC) 1 and 2 in the human endolymphatic sac (ES). METHODS A sample of human ES was harvested during the removal of vestibular schwannoma via the translabyrinthine approach. The sample was immediately fixed in 4% paraformaldehyde and embedded in OCT compound. Immunohistochemistry was performed with AQP1, 3, and 4, NKCC1, and NKCC2 polyclonal antibodies. RESULTS AQP1, AQP3, and NKCC2 were strongly expressed in the epithelial layer of the ES. AQP4 and NKCC1 were weakly expressed in the epithelial layer of the ES. CONCLUSIONS As it is impossible to perform quantitative analysis based on the fluorescence intensity of each immunoreactivity, we have presented the existence of AQP1, 3, and 4, NKCC1, and NKCC2 in the ES. The expression of NKCC1 and 2 indicated that the ES may have both secretory and adsorptive functions to maintain the homeostasis of endolymph.
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Affiliation(s)
- Akinobu Kakigi
- Department of Otolaryngology, Kochi Medical School, Nankoku, Japan.
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Abstract
Arginine-vasopressin is a hormone that plays an important part in circulatory and water homoeostasis. The three arginine-vasopressin-receptor subtypes--V1a, V1b, and V2--all belong to the large rhodopsin-like G-protein-coupled receptor family. The vaptans are orally and intravenously active non-peptide vasopressin receptor antagonists that are in development. Relcovaptan is a selective V1a-receptor antagonist, which has shown initial positive results in the treatment of Raynaud's disease, dysmenorrhoea, and tocolysis. SSR-149415 is a selective V1b-receptor antagonist, which could have beneficial effects in the treatment of psychiatric disorders. V2-receptor antagonists--mozavaptan, lixivaptan, satavaptan, and tolvaptan--induce a highly hypotonic diuresis without substantially affecting the excretion of electrolytes (by contrast with the effects of diuretics). These drugs are all effective in the treatment of euvolaemic and hypervolaemic hyponatraemia. Conivaptan is a V1a/V2 non-selective vasopressin-receptor antagonist that has been approved by the US Food and Drug Administration as an intravenous infusion for the inhospital treatment of euvolaemic or hypervolaemic hyponatraemia.
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Affiliation(s)
- Guy Decaux
- Department of Internal Medicine, Erasmus University Hospital, Brussels, Belgium.
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Taguchi D, Takeda T, Kakigi A, Takumida M, Nishioka R, Kitano H. Expressions of Aquaporin-2, Vasopressin Type 2 Receptor, Transient Receptor Potential Channel Vanilloid (TRPV)1, and TRPV4 in the Human Endolymphatic Sac. Laryngoscope 2007; 117:695-8. [PMID: 17415141 DOI: 10.1097/mlg.0b013e318031c802] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To localize aquaporin (AQP)2, vasopressin type 2 receptor (V2-R), and transient receptor potential channel vanilloid subfamily 1, 4 (TRPV1, TRPV4) in the human endolymphatic sac (ES). METHODS Three samples of human ES were sampled during the removal of vestibular schwannoma by way of the translabyrinthine approach. The samples were immediately fixed in 4% paraformaldehyde and embedded in OCT compound; immunohistochemistry was performed with AQP2, V2-R, TRPV1, and TRPV4 polyclonal antibodies. RESULTS AQP2, V2-R, TRPV1, and TRPV4 proteins were detected in the epithelial layer of the ES but were not observed in connective tissue around the ES. TRPV1 was also expressed in blood vascular endothelial cells of the connective tissue of ES. CONCLUSIONS AQP2, V2-R, and TRPV4 were expressed in the luminal epithelium of human ES. The same characteristic distribution of water and ion channels is seen in the kidney, where a significant amount of fluid is filtrated and resorbed. ES probably plays an active role in the homeostasis of the endolymph.
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Affiliation(s)
- Daizo Taguchi
- Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan.
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Abstract
PURPOSE OF REVIEW Review of the role of aquaporins in inner ear homeostasis and potential role in the pathogenesis of Meniere's disease. RECENT FINDINGS Recent findings include the immunolocalization of aquaporins in the inner ear of mouse, rat, and human to cell types that are likely to undergo high ionic perturbances (e.g. potassium flux) and to putative areas of endolymph resorption or cycling. SUMMARY The expression of aquaporins and related proteins in the human cochlea and vestibular periphery resembles the distribution found in animal models, suggesting a critical role of aquaporins in inner ear water homeostasis and their potential role in the pathogenesis of Meniere's disease.
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Affiliation(s)
- Gail Ishiyama
- Department of Neurology, Division of Head and Neck Surgery, David Geffen School of Medicine at the University of California, Los Angeles 90095, USA.
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Kakigi A, Takeda T, Sawada S, Taguchi D. Antidiuretic Hormone and Osmolality in Isosorbide Therapy and Glycerol Test. ORL J Otorhinolaryngol Relat Spec 2006; 68:279-82. [PMID: 16699291 DOI: 10.1159/000093299] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Accepted: 03/17/2006] [Indexed: 11/19/2022]
Abstract
Changes in plasma antidiuretic hormone (p-ADH) and plasma osmolality (p-Osm) levels were studied in 63 patients with Ménière's disease before and after isosorbide administration and a glycerol test. Increments in both p-ADH and p-Osm levels were observed after isosorbide administration and the glycerol test. The p-ADH secretion appeared to be secondarily stimulated by an increase in the p-Osm level. This p-ADH level increase affects cochlear fluid homeostasis. Based on these results, we must consider both the p-Osm and p-ADH levels when treating patients with Ménière's disease by osmotic diuretics.
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Affiliation(s)
- Akinobu Kakigi
- Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan.
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Abstract
OBJECTIVES/HYPOTHESIS We examined whether sufficient water intake is effective in the long-term control of vertigo and hearing activity in patients with Meniere disease (MD) for whom conventional therapy has proven unsuccessful. STUDY DESIGN The authors conducted a time-series study with historical control. METHODS Eighteen patients with MD in group 1 drank 35 mL/kg per day of water for 2 years. Twenty-nine patients with MD treated with the conventional dietary and diuretic therapy for more than 2 years during 1992 to 1999 at the same hospital were enrolled in a historical control of group 2. RESULTS Patients in group 1 dramatically relieved vertigo and significantly improved in the hearing of the worst pure-tone average of three frequencies (0.125, 0.25, and 0.5 kHz) (low PTA) during the last 6 months of the study period. In contrast, patients in group 2 became worse in both the four- (0.5, 1, 2, and 4 kHz) frequency PTA and the low PTA, although their vertigo did improve. The number of patients whose hearing were improved, unchanged, and worse were 4, 12, and 2 in group 1 and 2, 11, and 16 in group 2, respectively. CONCLUSION Deliberate modulation of the intake of water may be the simplest and most cost-effective medical treatment for patients with MD. Larger studies will be needed to confirm these results in a larger patient cohort.
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Affiliation(s)
- Hideaki Naganuma
- Department of Otorhinolaryngology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555, Japan.
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Takeda T, Takeda S, Kakigi A, Okada T, Nishioka R, Taguchi D. A comparison of dehydration effects of V2-antagonist (OPC-31260) on the inner ear between systemic and round window applications. Hear Res 2006; 218:89-97. [PMID: 16781097 DOI: 10.1016/j.heares.2006.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 04/28/2006] [Accepted: 05/01/2006] [Indexed: 10/24/2022]
Abstract
V2-antagonist (OPC-31260 (OPC)) application to the scala tympani reduced endolymphatic hydrops. In the present study, we investigated whether systemic administration or local infusion via the round window (RW application) of OPC would be more suitable for clinical use. In Experiment 1, the increase ratios of the cross-sectional area of the scala media of experimentally induced endolymphatic hydrops were quantitatively assessed among four groups of non-OPC application, RW application of xanthan gum, systemic application of OPC and RW application of OPC. In Experiment 2, the effects of systemic and RW applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM) were investigated. In Experiment 3, endocochlear DC potential (EP) was measured in guinea pigs with the RW application of OPC. Electron microscopic observations of the stria vascularis and the hair cells were also made. Both systemic and RW applications of OPC significantly reduced endolymphatic hydrops. However, systemic application resulted in the distension of the Reissner's membrane in the non-operated ear, which seemed to be caused by elevated p-VP levels resulting from the systemic application of OPC. In contrast, RW application of OPC produced no apparent toxic effects in the inner ear, as indicated electrophysiological or morphological changes. Thus, drug delivery via the round window is more useful for the clinical application of OPC for medical decompression.
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Affiliation(s)
- Taizo Takeda
- Department of Otolaryngology, Kochi Medical School, Kohasu, Kochi 783-8505, Japan.
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Couloigner V, Sterkers O, Ferrary E. What's new in ion transports in the cochlea? Pflugers Arch 2006; 453:11-22. [PMID: 16773381 DOI: 10.1007/s00424-006-0103-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 05/02/2006] [Indexed: 11/26/2022]
Abstract
Recent advances in the field of the physiology of inner ear fluids permitted the characterization of the molecular mechanisms involved in critical processes such as the absorption of K(+) through cochlear sensory hair cells (mechanoelectrical transduction) or the secretion of K(+) by marginal cells of the stria vascularis. In addition, new pathways for ion circulations were evidenced. Mutations of transporters involved in some of these pathways, especially in K(+) recycling through gap junction systems, and in local pH regulation, are among the most frequent etiologies of genetic deafness in humans.
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Affiliation(s)
- Vincent Couloigner
- Inserm EMI U-0112, Faculté Xavier Bichat, 16, rue Henri Huchard, Paris 75018, France.
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Semaan MT, Alagramam KN, Megerian CA. The basic science of Meniere's disease and endolymphatic hydrops. Curr Opin Otolaryngol Head Neck Surg 2006; 13:301-7. [PMID: 16160525 DOI: 10.1097/01.moo.0000186335.44206.1c] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW Meniere's disease is characterized by the triad of fluctuating hearing loss, episodic vertigo, and tinnitus and by endolymphatic hydrops found on post-mortem examination. The cause of Meniere's disease remains unclear. Numerous factors play a role in the development of hydrops and in the pathogenesis of related cochleovestibular dysfunction. This review highlights recent advances in the understanding of the pathophysiology of symptom development in Meniere's disease by detailing the role of genetics, autoimmunity, endolymphatic fluid homeostasis, excitotoxicity, oxidative stress, and cellular apoptosis. Emphasis is placed on reviewing the newly described animal models that exhibit endolymphatic hydrops. RECENT FINDINGS Recent evidence suggests that hearing loss might be explained in part by apoptosis of spiral ganglion neurons and that hydrops could represent an epiphenomenon rather than an initiating factor. In addition, the accepted guinea pig model described by Kimura has certain limitations. An animal model that would supplement and in some cases replace the surgically induced model is currently being sought. SUMMARY These recent advances have expanded our understanding and will allow for the development of targeted therapeutic interventions aimed at preventing the progression oochleovestibular deterioration.
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Affiliation(s)
- Maroun T Semaan
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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Fukushima K, Takeda T, Kakigi A, Takeda S, Sawada S, Nishioka R, Azuma H, Taguchi T. Effects of lithium on endolymph homeostasis and experimentally induced endolymphatic hydrops. ORL J Otorhinolaryngol Relat Spec 2005; 67:282-8. [PMID: 16374061 DOI: 10.1159/000089409] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is evidence to suggest that water homeostasis in the inner ear is regulated via the vasopressin (VP)-aquaporin 2 (AQP2) system in the same fashion as in the kidney. The VP-AQP2 system in the kidney is well known to be inhibited by lithium, resulting in polyuria due to a decrease in reabsorption of water in the collecting duct of the kidney. Therefore, lithium is also likely to inhibit the VP-AQP2 system in the inner ear, and consequently exert some influence on inner ear fluid homeostasis. In this study, we investigated the effects of lithium on AQP2 expression in the rat inner ear, and on the cochlear fluid volume in hydropic ears of guinea pigs. A quantitative PCR study revealed that lithium reduced AQP2 mRNA expression in the cochlea and endolymphatic sac. Lithium application also decreased the immunoreactivity of AQP2 in the cochlea and endolymphatic sac. In a morphological study, lithium intake significantly reduced endolymphatic hydrops dose-dependently. These results indicate that lithium acts on the VP-AQP2 system in the inner ear, consequently producing a dehydratic effect on the endolymphatic compartment.
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Affiliation(s)
- K Fukushima
- Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan
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Abstract
Water homeostasis during fetal development is of crucial physiologic importance. It depends upon maternal fetal fluid exchange at the placenta and fetal membranes, and some exchange between fetus and amniotic fluid can occur across the skin before full keratinization. Lungs only grow and develop normally with fluid secretion, and there is evidence that cerebral spinal fluid formation is important in normal brain development. The aquaporins are a growing family of molecular water channels, the ontogeny of which is starting to be explored. One question that is of particular importance is how well does the rodent (mouse, rat) fetus serve as a model for long-gestation mammals such as sheep and human? This is particularly important for organs such as the lung and the kidney, whose development before birth is very much less in rodents than in the long-gestation species.
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Affiliation(s)
- Huishu Liu
- Guangzhou Obstetric and Gynecology Institute, Second Municipal Hospital of Guangzhou, Guangzhou Medical College, Guangzhou, PR China
| | - E Marelyn Wintour
- Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
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Horner KC, Cazals Y. Stress hormones in Ménière's disease and acoustic neuroma. Brain Res Bull 2005; 66:1-8. [PMID: 15925138 DOI: 10.1016/j.brainresbull.2005.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Revised: 04/01/2005] [Accepted: 04/07/2005] [Indexed: 02/04/2023]
Abstract
Stress has been postulated to trigger or contribute to inner ear pathologies but there is little objective evidence. We investigated stress hormones in Ménière's patients and patients with acoustic neuroma. Data were compared with those from a control group of patients with facial spasm. We assayed classic stress hormones including adrenocorticotropic hormone, cortisol, growth hormone and prolactin. We found a strong positive correlation between cortisol and adrenocorticotropic hormone in Ménière patients and patients with acoustic neuroma but no correlation in patients with facial spasm. The data also revealed in female patients with Ménière's disease or with acoustic neuroma an unexpected significant positive correlation between cortisol and prolactin. The data showed the expected negative correlation or no correlation between cortisol and prolactin associated with males and females in the other patient groups. Both cortisol and prolactin increases are known to represent alternative strategies to cope with stress, and our data point to prolactin being possibly more dominant in Ménière's disease and cortisol in acoustic neuroma. These data provide further evidence for modification of different stress hormones in audiovestibular pathologies, which might provide a valuable diagnostic or prognostic tool in the future.
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Affiliation(s)
- Kathleen C Horner
- Laboratoire de Physiologie Neurovégétative, Cnrs UMR 6153, 1147 INRA, Université Paul Cézanne, Faculté des Sciences St. Jérôme, Cases 351-352, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France.
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Valk WL, Wit HP, Segenhout JM, Dijk F, van der Want JJL, Albers FWJ. Morphology of the endolymphatic sac in the guinea pig after an acute endolymphatic hydrops. Hear Res 2005; 202:180-7. [PMID: 15811710 DOI: 10.1016/j.heares.2004.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Accepted: 10/21/2004] [Indexed: 11/25/2022]
Abstract
The role of the endolymphatic sac (ES) in endolymph volume homeostasis is speculative. The present study investigates changes of the ES's epithelia and luminal filling after induction of an acute endolymphatic hydrops. After microinjection of 1.1 mul artificial endolymph into scala media of the cochlea, guinea pigs were terminated immediately (n = 6) or after different time intervals ; 1/2 h (n = 3), 1 h (n = 4) and 2 h (n = 4). Inner ear specimens were processed for light and/or transmission electron microscopy. The non-injected contralateral ear served as a histological control. Correct injection was confirmed by detection of microspheres in the endolymphatic compartment after the same microinjection procedure. In all specimens, ribosome rich cells and intraluminal macrophages appeared to be actively involved in degradation of homogeneous substance (HS) by secreting lytic enzymes and digestion, respectively. Amazingly, in our study no ES differences were found between injected and non-injected ears and no distinct changes were observed in guinea pigs terminated after different time intervals. The ES's luminal HS was always present and often to a large extent. This is in contrast with [Hear. Res. 138, 81] dramatic changes were observed. Endolymph volume homeostasis is a complex mechanism, in which the role of HS remains obscure.
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Affiliation(s)
- W L Valk
- Department of Otorhinolaryngology, University Hospital Groningen, Netherlands.
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Affiliation(s)
- H Löwenheim
- Universitäts-Hals-Nasen-Ohren-Klinik Tübingen.
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Abstract
PURPOSE OF REVIEW Meniere disease has long been postulated to be a disorder of intralabyrinthine fluid dynamics. RECENT FINDINGS More recent developments in this field indicate that the control of fluid movement may be at a cellular level and that hormonal influence may be important. SUMMARY The control of fluid and ion movements through aquaporins and gap junctions in the cell membranes are creating new perspectives in the mechanism of development of endolymphatic hydrops as well as potential methods for treatment. Intralabyrinthine fluid dynamics also play a role in the ability to locally deliver drugs to the inner ear through the middle ear.
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Affiliation(s)
- James C Andrews
- Division of Head and Neck Surgery, Sepulveda-UCLA Veterans Administration Hospital, 16111 Plummer Street, Sepulveda, CA 91343, USA.
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Couloigner V, Berrebi D, Teixeira M, Paris R, Florentin A, Bozorg Grayeli A, Cluzeaud F, Sterkers O, Peuchmaur M, Ferrary E. Aquaporin-2 in the human endolymphatic sac. Acta Otolaryngol 2004; 124:449-53. [PMID: 15224873 DOI: 10.1080/00016480310000700a] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To detect and localize aquaporin-2 (AQP-2), a water channel regulated by the antidiuretic hormone, in human endolymphatic sac. MATERIAL AND METHODS Human endolymphatic sacs were sampled during removal of vestibular schwannomas via a translabyrinthine approach. Samples were immediately fixed in 10% formalin (24 h) and embedded in paraffin; in situ hybridization and immunohistochemistry were performed with an AQP-2-specific probe and a polyclonal antibody. RESULTS Both AQP-2 mRNA and protein were detected in the epithelium of the endolymphatic sac. AQP-2 immunostaining was mainly cytoplasmic, suggesting that most AQP-2 was located in intracellular pools. CONCLUSIONS In the endolymphatic sac, AQP-2 probably participates in the homeostasis of endolymph; the possibility of reducing the volume of endolymph by inhibiting its expression and membranous insertion using an antidiuretic hormone inhibitor represents a new therapeutic approach for the treatment of Ménière's disease.
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