1
|
Jang CH, Cho YB, Choi CH, Um JY, Wang PC, Pak SC. The effect of topically administered latanoprost on the cochlear blood flow and hearing. Int J Pediatr Otorhinolaryngol 2013; 77:981-5. [PMID: 23611671 DOI: 10.1016/j.ijporl.2013.03.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 03/19/2013] [Accepted: 03/22/2013] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The application of intratympanic latanoprost (PGF2α analog) has been recently used to alleviate vertigo, disequilibrium and to improve hearing in Meniere's disease patients. However, there is no known report on the effect of topically applied latanoprost on hearing and cochlear hemodynamic parameters including cochlear blood flow (CBF) and vascular conductance. Our goal was to assess the influence of topically applied latanoprost on cochlear blood flow (CBF) and hearing. MATERIALS AND METHODS Twenty male Sprague-Dawley rats were randomly divided into the group A, 50 μl of latanoprost (1 ml containing 50 μg, n=10) and group B, 100 μl (1 ml containing 50 μg, n=10). Topical application of latanoprost was performed at the right side, and the left side was applied with phosphate buffered saline (PBS) as a negative control. Five rats at each group were used to measure cochlear blood flow (CBF). And the others at each group were used for hearing test by auditory brainstem response (ABR). After physiological examination, bullas were extracted. The changes of cochlear hair cells were observed by performing the field emission-scanning electron microscopy (FE-SEM). RESULTS The CBF of both groups was found to be decreased compared to the PBS applied left side. Significant decrement of CBF was observed in group B compared to the group A. Significant elevation of hearing threshold at high frequencies was observed in both groups compared to the PBS applied group. However, inner and outer hair cells were intact. CONCLUSION Topically administered latanoprost decreased the CBF and impaired hearing. Based on our findings, additional studies are required to evaluate the side effects of intratympanic latanoprost before its use in clinical practice.
Collapse
Affiliation(s)
- Chul Ho Jang
- Department of Otoalaryngology, Chonnam National University Medical School, Gwangju, South Korea.
| | | | | | | | | | | |
Collapse
|
2
|
Liu J, Yu P, Lin Y, Zhou N, Li T, Ma F, Mao L. In vivo electrochemical monitoring of the change of cochlear perilymph ascorbate during salicylate-induced tinnitus. Anal Chem 2012; 84:5433-8. [PMID: 22703231 DOI: 10.1021/ac301087v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
As one of the most important neurochemicals in biological systems, ascorbate plays vital roles in many physiological and pathological processes. In order to understand the roles of ascorbate in the pathological process of tinnitus, this study demonstrates an in vivo method for real time monitoring of the changes of ascorbate level in the cochlear perilymph of guinea pigs during the acute period of tinnitus induced by local microinfusion of salicylate with carbon fiber microelectrodes (CFMEs) modified with multiwalled carbon nanotubes (MWNTs). To accomplish in vivo electrochemical monitoring of ascorbate in the microenvironment of the cochlear perilymph, the MWNT-modified CFME is used as working electrode, a microsized Ag/AgCl is used as reference electrode, and Pt wire is used as counter electrode. Three electrodes are combined together around a capillary to form integrated capillary-electrodes. The integrated capillary-electrode is carefully implanted into the cochlear perilymph of guinea pigs and used both for externally microinfusing of salicylate into the cochlear perilymph and for real time monitoring of the change of ascorbate levels. The in vivo voltammetric method based on the integrated capillary-electrodes possesses a high selectivity and a good linearity for ascorbate determination in the cochlear perilymph of guinea pigs. With such a method, the basal level of cochlear perilymph ascorbate is determined to be 45.0 ± 5.1 μM (n = 6). The microinfusion of 10 mM salicylate (1 μL/min, 5 min) into the cochlear decreases the ascorbate level to 28 ± 10% of the basal level (n = 6) with a statistical significance (P < 0.05), implying that the decrease in ascorbate level in the cochlear may be associated with salicylate-induced tinnitus. This study essentially offers a new method for in vivo monitoring of the cochlear perilymph ascorbate following the salicylate-induced tinnitus and can thus be useful for investigation on chemical essences involved in tinnitus.
Collapse
Affiliation(s)
- Junxiu Liu
- Department of Otorhinolaryngology, Peking University Third Hospital, Beijing 100083, P. R. China
| | | | | | | | | | | | | |
Collapse
|
3
|
Role of PGE-type receptor 4 in auditory function and noise-induced hearing loss in mice. Neuropharmacology 2011; 62:1841-7. [PMID: 22198478 DOI: 10.1016/j.neuropharm.2011.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/16/2011] [Accepted: 12/07/2011] [Indexed: 12/18/2022]
Abstract
This study explored the physiological roles of PGE-type receptor 4 (EP4) in auditory function. EP4-deficient mice exhibited slight hearing loss and a reduction of distortion-product otoacoustic emissions (DPOAEs) with loss of outer hair cells (OHCs) in cochleae. After exposure to intense noise, these mice showed significantly larger threshold shifts of auditory brain-stem responses (ABRs) and greater reductions of DPOAEs than wild-type mice. A significant increase of OHC loss was confirmed morphologically in the cochleae of EP4-deficient mice. Pharmacological inhibition of EP4 had a similar effect to genetic deletion, causing loss of both hearing and OHCs in C57BL/6 mice, indicating a critical role for EP4 signaling in the maintenance of auditory function. Pharmacological activation of EP4 significantly protected OHCs against noise trauma, and attenuated noise-induced hearing loss in C57BL/6 mice. These findings suggest that EP4 signaling is necessary for the maintenance of cochlear physiological function and for cochlear protection against noise-induced damage, in particular OHCs. EP4 might therefore be an effective target for cochlear disease therapeutics.
Collapse
|
4
|
Abstract
Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature.
Collapse
Affiliation(s)
- Xiaorui Shi
- Oregon Hearing Research Center (NRC04), Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
| |
Collapse
|
5
|
Nakagawa T. Roles of prostaglandin E2 in the cochlea. Hear Res 2011; 276:27-33. [PMID: 21295127 DOI: 10.1016/j.heares.2011.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 01/15/2011] [Accepted: 01/19/2011] [Indexed: 12/20/2022]
Abstract
Prostaglandins are one of the major groups of chemical mediators in the mammalian body. Among prostaglandins, prostaglandin E2 (PGE2) is the most abundant prostanoid in humans and involved in regulating many different fundamental biological functions. PGE2 signaling is mediated by four distinct E-prostanoid receptors (EPs) namely EP1-4. Recently, accumulating evidence indicates critical, but complex roles of EP signaling in the pathogenesis of neuronal diseases depending on the context of neuronal injury. Four distinct EPs are expressed in the stria vascularis, spiral ligament, spiral ganglion and organ of Corti, indicating an involvement of EP signaling in the cochlear function. Activation of EP4 in cochleae significantly attenuates noise-induced damage in cochleae, and activation of EP2 or EP4 induces the formation of vascular endothelial growth factor in cochleae. These findings strongly suggest that individual EP signaling may be involved in the maintenance of the cochlear sensory system similarly to the central nervous system. This review highlights recent findings on EP signaling in the central nervous system, and presents its possible roles in regulation of blood flow, protection of sensory cells and immune responses in cochleae.
Collapse
Affiliation(s)
- Takayuki Nakagawa
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyoku, Kyoto 606-8507, Japan.
| |
Collapse
|
6
|
Heinrich UR, Selivanova O, Schmidtmann I, Feltens R, Brieger J, Mann WJ. Noise exposure alters cyclooxygenase 1 (COX-1) and 5-lipoxygenase (5-LO) expression in the guinea pig cochlea. Acta Otolaryngol 2010. [DOI: 10.3109/00016480903168066] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
7
|
Hori R, Nakagawa T, Sugimoto Y, Sakamoto T, Yamamoto N, Hamaguchi K, Ito J. Prostaglandin E receptor subtype EP4 agonist protects cochleae against noise-induced trauma. Neuroscience 2009; 160:813-9. [DOI: 10.1016/j.neuroscience.2009.03.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 02/02/2009] [Accepted: 03/08/2009] [Indexed: 12/19/2022]
|
8
|
Suzuki H, Fujimura T, Shiomori T, Ohbuchi T, Kitamura T, Hashida K, Udaka T. Prostaglandin E1 versus steroid in combination with hyperbaric oxygen therapy for idiopathic sudden sensorineural hearing loss. Auris Nasus Larynx 2008; 35:192-7. [PMID: 17826927 DOI: 10.1016/j.anl.2007.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2007] [Revised: 04/29/2007] [Accepted: 06/04/2007] [Indexed: 10/22/2022]
Abstract
OBJECTIVE We conducted a controlled retrospective analysis of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) in order to investigate the effect of prostaglandin E1 (PGE1) plus hyperbaric oxygen (HBO) therapy in comparison with that of steroid plus HBO therapy. METHODS One hundred and ninety-six consecutive patients with ISSNHL (hearing levels > or ==40dB; time from the onset of hearing loss to the start of treatment < or ==30 days) were enrolled. Ninety-five patients underwent PGE1 plus HBO therapy (PG group) and 101 underwent steroid administration plus HBO therapy (steroid group). Hearing recovery was evaluated by grade assessment and by the improvement in hearing compared to the unaffected contralateral ear. RESULTS The hearing levels after treatment were 52.2+/-3.0 and 47.5+/-2.8dB, the hearing gains were 31.3+/-2.2 and 27.2+/-2.3dB, the cure rates were 28.4% and 28.7%, the recovery rates were 54.7% and 53.5%, and the hearing improvement rates were 48.4+/-5.1% and 53.9+/-4.2% in the PG and steroid groups, respectively. There were no significant differences between the two groups. CONCLUSION We concluded that PGE1 and a steroid are equally effective in the treatment of ISSNHL when used together with HBO therapy. PGE1 plus HBO therapy can be one of the potential alternative treatments for ISSNHL, particularly in steroid-intolerant patients such as those with severe diabetes mellitus, an active peptic ulcer, or viral hepatitis.
Collapse
Affiliation(s)
- Hideaki Suzuki
- Department of Otorhinolaryngology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
| | | | | | | | | | | | | |
Collapse
|
9
|
Suzuki H, Fujimura T, Ikeda K, Shiomori T, Udaka T, Ohbuchi T, Nagatani G. Prostaglandin E1 in combination with hyperbaric oxygen therapy for idiopathic sudden sensorineural hearing loss. Acta Otolaryngol 2008; 128:61-5. [PMID: 17851957 DOI: 10.1080/00016480701387082] [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: 10/22/2022]
Abstract
CONCLUSIONS Prostaglandin E1 (PGE1) is less effective than stellate ganglion block (SGB) in the treatment of idiopathic sudden sensorineural hearing loss (ISSNHL) patients with severe hearing losses when used together with hyperbaric oxygen (HBO) therapy. In contrast with the systemic action of intravenous PGE1, SGB's localized vasodilating action may explain its advantage over intravenous PGE1. OBJECTIVES To investigate the effect of PGE1 plus HBO therapy on ISSNHL in comparison with that of SGB plus HBO therapy. PATIENTS AND METHODS We retrospectively analyzed 205 consecutive patients with ISSNHL (hearing levels > or = 40 dB; time from the onset of hearing loss to the start of treatment < or = 30 days). Ninety-five patients underwent intravenous PGE1 plus HBO therapy (PG group) and 110 underwent SGB plus HBO therapy (SGB group). Hearing recovery was evaluated by grade assessment and by hearing improvement compared to that in the unaffected contralateral ear. RESULTS The overall hearing outcome was not statistically different between the two groups. For patients with initial hearing levels <80 dB, the groups had roughly equivalent hearing outcomes, whereas in patients with initial hearing levels > or = 80 dB, the hearing improvement rate was significantly higher in the SGB group than in the PG group (53.0 +/- 5.0% vs 35.3 +/- 6.8%; p <0.05).
Collapse
Affiliation(s)
- Hideaki Suzuki
- Department of Otorhinolaryngology, School of Medicine, University of Occupational and Environmental Health, Yahatanishi-ku, Kitakyushu, Japan.
| | | | | | | | | | | | | |
Collapse
|
10
|
Tariq M, Khan HA, Siddiquei MM, Al Moutaery K, Al Deeb S. Protective effect of hydrocortisone on iminodipropionitrile-induced neurotoxicity in rats. Basic Clin Pharmacol Toxicol 2007; 100:176-81. [PMID: 17309521 DOI: 10.1111/j.1742-7843.2006.00037.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Occupational and environmental exposure of synthetic nitriles is of potential relevance to human health. Iminodipropionitrile (IDPN), a prototype nitrile toxin, has been shown to produce dyskinetic syndrome in rodents. This study reports the effect of concomitant exposure of rats to hydrocortisone and IDPN on behavioural abnormalities namely excitation, circling and chorea (ECC) syndrome. Four groups of female Wistar rats were given hydrocortisone (0, 10, 30 and 60 mg/kg, gavage, for 10 days) 30 min. before IDPN (100 mg/kg, intraperitoneally for 8 days). Two additional groups of rats were treated with either saline (control group) or 60 mg/kg of hydrocortisone (drug alone group). The animals were observed for neurobehavioural abnormalities including dyskinetic head movement, circling, tail hanging, air righting reflex and contact inhibition of righting reflex. After behavioural studies, the animals were killed, and the discrete brain regions and temporal bones were collected for biochemistry and inner ear histopathology, respectively. Hydrocortisone significantly and dose dependently attenuated the incidence and severity of IDPN-induced behavioural syndrome. Administration of hydrocortisone (60 mg/kg) alone significantly increased glutathione (GSH) levels in olfactory bulb and striatum, whereas IDPN alone significantly reduced GSH levels in olfactory bulb, striatum and hippocampus. Hydrocortisone (60 mg/kg) significantly compensated IDPN-induced depletions of GSH in different brain regions. Hydrocortisone also protected the animals against IDPN-induced vestibular hair cell degeneration. The protective effect of hydrocortisone may be attributed to its anti-inflammatory and antioxidant properties.
Collapse
Affiliation(s)
- Mohammad Tariq
- Neuroscience Research Group, Armed Forces Hospital, Riyadh, Saudi Arabia.
| | | | | | | | | |
Collapse
|
11
|
Tominaga M, Yamamoto H, Sone M, Teranishi MA, Nakashima T. Response of cochlear blood flow to prostaglandin E1 applied topically to the round window. Acta Otolaryngol 2006; 126:232-6. [PMID: 16618646 DOI: 10.1080/00016480500316803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONCLUSIONS The increase in cochlear blood flow (CBF) after administration of prostaglandin E1 (PGE1) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA). OBJECTIVES To evaluate the response of CBF to PGE1 applied topically to the round window, and to investigate the origin of blood flow changes after this topical application. MATERIAL AND METHODS The response of CBF to topically applied PGE1 was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats. In rats, the CBF response to PGE1 administration was investigated after occlusion of the AICA or stapedial artery. RESULTS CBF increased following PGE1 administration in both guinea pigs and rats. In rats, CBF increased from 100% to 132%+/-10% (mean+/-SD) after the topical application of 0.5 microl of a 0.014% PGE1 solution. CBF decreased after occlusion of the AICA or stapedial artery but did not increase after PGE1 administration during occlusion of the AICA. The CBF response to PGE1 administration was similar before and after occlusion of the stapedial artery.
Collapse
Affiliation(s)
- Mitsuo Tominaga
- Department of Otorhinolaryngology, Nagoya University School of Medicine, Nagoya, Japan
| | | | | | | | | |
Collapse
|
12
|
Heinrich UR, Brieger J, Selivanova O, Feltens R, Eimermacher A, Schäfer D, Mann WJ. COX-2 expression in the guinea pig cochlea is partly altered by moderate sound exposure. Neurosci Lett 2005; 394:121-6. [PMID: 16289316 DOI: 10.1016/j.neulet.2005.10.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 09/27/2005] [Accepted: 10/05/2005] [Indexed: 11/16/2022]
Abstract
The cyclooxygenase-2 isoform (COX-2) was found recently to be constitutively expressed in the guinea pig inner ear. To gain knowledge about its role in sound perception, alterations in the COX-2 level of moderate noise-stimulated cochleae were determined. Staining intensities were quantified in different regions using an immunohistochemical staining procedure and computer-assisted system. After 70 dB and 90 dB noise exposure for 1 h at 8000 Hz, COX-2 downregulation was observed in the organ of Corti, which was most prominent in Deiters' cells near Hensen cells and outer hair cells. In pillar cells, COX-2 levels were only slightly reduced after 70 dB but strongly diminished after 90 dB exposure. In Hensen cells, COX-2 was downregulated after 70 dB stimulation, revealing a decreasing COX-2 content from the third to the first turn of the cochlea and a homogeneously reduced enzyme expression in all three turns after 90 dB. The COX-2 content in inner hair cells was nearly identical to unexposed cochleae after 70 dB exposure but significantly reduced after 90 dB stimulation. In spiral ganglion cells, stria vascularis, spiral ligament and limbus, COX-2 expression was unchanged after 70 dB and 90 dB. We suggest that alterations in COX-2 expression might contribute to diminished sensitivity at the cochlea after noise exposure to reduce subsequent noise distress, termed sound conditioning.
Collapse
Affiliation(s)
- Ulf-Rüdiger Heinrich
- Department of Otolaryngology - Head and Neck Surgery, Johannes Gutenberg University Medical School, Mainz, Germany.
| | | | | | | | | | | | | |
Collapse
|
13
|
Stjernschantz J, Wentzel P, Rask-Andersen H. Localization of prostanoid receptors and cyclo-oxygenase enzymes in Guinea pig and human cochlea. Hear Res 2004; 197:65-73. [PMID: 15504605 DOI: 10.1016/j.heares.2004.04.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 04/29/2004] [Indexed: 11/16/2022]
Abstract
Endogenous production of prostaglandins has been demonstrated in the cochlea, but no information is available on the distribution of the cyclo-oxygenase (COX) enzymes, or prostanoid receptors in the cochlea. The purpose of the present study was to investigate the localization of the FP, EP(1) and EP(3) prostanoid receptors as well as the COX-1 and COX-2 enzymes in the cochlea of guinea pig and man. Cochleas were processed for immunohistochemistry using routine techniques. Appropriate controls comprised incubation with specific blocking peptides, or incubation without primary antibodies. Both in guinea pig and man the FP prostanoid receptor was abundantly distributed in the cochlea, e.g., in stria vascularis, the spiral ligament, spiral ganglion, and organ of Corti. The immunohistochemical staining of the EP(1) and EP(3) receptors in the same structures was significantly weaker and sometimes lacking altogether (e.g., EP(3) receptor in human cochlea). Weak, but mostly consistent immunostaining of the COX-1 enzyme was found in the cochlear structures. The COX-2 enzyme appeared to be lacking. The abundant distribution of the FP receptor in several important cochlear structures both in guinea pig and man suggests a physiological function for PGF(2alpha) in the cochlea. The COX-1 enzyme seems to be constitutively expressed in the cochlea in contrast to COX-2.
Collapse
Affiliation(s)
- Johan Stjernschantz
- Department of Neuroscience, Unit of Pharmacology, Uppsala University, SE-751 24 Uppsala, Sweden.
| | | | | |
Collapse
|
14
|
Sone M, Hayashi H, Yamamoto H, Tominaga M, Nakashima T. A comparative study of intratympanic steroid and NO synthase inhibitor for treatment of cochlear lateral wall damage due to acute otitis media. Eur J Pharmacol 2004; 482:313-8. [PMID: 14660037 DOI: 10.1016/j.ejphar.2003.09.051] [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: 10/26/2022]
Abstract
We studied the damage to the cochlear lateral wall induced by otitis media and the therapeutic effects of intratympanic administration of steroid and nitric oxide (NO) synthase inhibitor. In Sprague-Dawley rats, right middle ear cavities were inoculated with lipopolysaccharide, followed after 30 min by intratympanic administration of dexamethasone, NOS-inhibitor or PBS. Twenty-four hours after lipopolysaccharide inoculation, cochlear blood flow was measured by laser-Doppler flowmetry. Prostaglandin E(1) was topically applied to the round window membrane of the right ear and changes in cochlear blood flow were calculated. Changes of cochlear blood flow were significantly different among the three groups. Increases in cochlear blood flow following PGE(1) application were higher in the group that received NOS-inhibitor. Electron microscopic examination revealed that changes in the stria vascularis were less severe in rats treated with dexamethasone or NOS-inhibitor. Our results show the effectiveness of intratympanic dexamethasone or NOS-inhibitor in treating cochlear lateral wall damage caused by otitis media.
Collapse
Affiliation(s)
- Michihiko Sone
- Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa, Nagoya 466-8550, Japan.
| | | | | | | | | |
Collapse
|
15
|
Ziegler EA, Brieger J, Heinrich UR, Mann WJ. Immunohistochemical Localization of Cyclooxygenase Isoforms in the Organ of Corti and the Spiral Ganglion Cells of Guinea Pig Cochlea. ACTA ACUST UNITED AC 2004; 66:297-301. [PMID: 15668527 DOI: 10.1159/000081885] [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] [Received: 12/11/2003] [Accepted: 07/22/2004] [Indexed: 12/13/2022]
Abstract
Prostaglandins have been used in experimental models and clinical studies for the therapy of sudden hearing loss and tinnitus with conflicting results. However, little is known about the rate-limiting enzymes of prostaglandin synthesis in the inner ear, the generally constitutively expressed cyclooxygenase 1 (COX-1) and the distress-inducible cyclooxygenase 2 (COX-2). To extend our knowledge concerning the physiological expression and localization of these two enzymes, immunohistochemical stainings of the guinea pig cochlea were performed. Light microscopical analysis revealed a homogenous distribution of COX-1 within nearly all cell types of the organ of Corti, but no COX-1 expression in the cuticular plates of pillar cells. COX-2 was found to be expressed in all cell types, with much stronger expression in Hensen cells, neighboring Deiters cells and cuticular plates of outer hair cells. Both COX-1 and COX-2 immunoreactions were also found in the spiral ganglion. We conclude that both COX subtypes are expressed in the guinea pig cochlea under physiological conditions. The prominent expression of the distress-inducible COX-2 isoform in cell types under mechanical stress during noise reception might support the hypothesis of a cytoprotective function of COX products in hearing and in cellular stress situations like intense noise exposure.
Collapse
Affiliation(s)
- E A Ziegler
- Department of Otorhinolaryngology, Head and Neck Surgery, Johannes Gutenberg University Medical School, Mainz, Germany
| | | | | | | |
Collapse
|
16
|
Ohinata Y, Miller JM, Altschuler RA, Schacht J. Intense noise induces formation of vasoactive lipid peroxidation products in the cochlea. Brain Res 2000; 878:163-73. [PMID: 10996147 DOI: 10.1016/s0006-8993(00)02733-5] [Citation(s) in RCA: 193] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study investigates the correlation between the formation of reactive oxygen species (ROS) and auditory damage in noise-induced hearing loss. The noise exposure (4-kHz octave band, 115 dB SPL, 5 h) created permanent threshold shifts at frequencies from 2 to 20 kHz. The lipid peroxidation product, 8-isoprostane, was determined biochemically and histochemically as an indicator of ROS. Noise exposure increased 8-isoprostane levels in the cochlea in a time-dependent manner. After 5 h of exposure, 8-isoprostane levels were more than 30-fold greater than baseline, and decreased rapidly after the termination of noise. The immunoreactivity to 8-isoprostane was increased in the stria vascularis, spiral ganglion cells and the organ of Corti. In the organ of Corti, immunostaining was restricted to the second turn in a region 10-12 mm from the apex. This region sustained most of the permanent hair cell damage as revealed in surface preparations. Outer hair cells were more heavily immunostained than inner hair cells while Hensen's cells showed still less immunostain. These data are consistent with the view that ROS are involved in noise-induced damage. However, the relationship between ROS formation and tissue damage appears complex. In the organ of Corti, the pattern of noise-induced lipid peroxidation correlates well with subsequent morphological damage. The stria vascularis, however, does not sustain permanent damage despite intense lipid peroxidation. Differences in endogenous antioxidant levels and commitment to different apoptotic or survival pathways may underlie such differential responses.
Collapse
Affiliation(s)
- Y Ohinata
- Kresge Hearing Research Institute, The University of Michigan, 1301 East Ann Street, Ann Arbor, MI 48109-0506, USA
| | | | | | | |
Collapse
|