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Tan HT, Smith PF, Zheng Y. Time-dependent effects of acoustic trauma and tinnitus on extracellular levels of amino acids in the inferior colliculus of rats. Hear Res 2024; 443:108948. [PMID: 38219615 DOI: 10.1016/j.heares.2024.108948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/19/2023] [Accepted: 01/02/2024] [Indexed: 01/16/2024]
Abstract
Chronic tinnitus is a debilitating condition with very few management options. Acoustic trauma that causes tinnitus has been shown to induce neuronal hyperactivity in multiple brain areas in the auditory pathway, including the inferior colliculus. This neuronal hyperactivity could be attributed to an imbalance between excitatory and inhibitory neurotransmission. However, it is not clear how the levels of neurotransmitters, especially neurotransmitters in the extracellular space, change over time following acoustic trauma and the development of tinnitus. In the present study, a range of amino acids were measured in the inferior colliculus of rats during acoustic trauma as well as at 1 week and 5 months post-trauma using in vivo microdialysis and high-performance liquid chromatography. Amino acid levels in response to sound stimulation were also measured at 1 week and 5 months post-trauma. It was found that unilateral exposure to a 16 kHz pure tone at 115 dB SPL for 1 h caused immediate hearing loss in all the animals and chronic tinnitus in 58 % of the animals. Comparing to the sham condition, extracellular levels of GABA were significantly increased at both the acute and 1 week time points after acoustic trauma. However, there was no significant difference in any of the amino acid levels measured between sham, tinnitus positive and tinnitus negative animals at 5 months post-trauma. There was also no clear pattern in the relationship between neurochemical changes and sound frequency/acoustic trauma/tinnitus status, which might be due to the relatively poorer temporal resolution of the microdialysis compared to electrophysiological responses.
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Affiliation(s)
- Huey Tieng Tan
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand
| | - Paul F Smith
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand
| | - Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand.
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2
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Zimdahl JW, Rodger J, Mulders WHAM. Acoustic trauma increases inhibitory effects of amygdala electrical stimulation on thalamic neurons in a rat model. Hear Res 2023; 439:108891. [PMID: 37797476 DOI: 10.1016/j.heares.2023.108891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/25/2023] [Accepted: 09/20/2023] [Indexed: 10/07/2023]
Abstract
Acoustic trauma (AT) induced hearing loss elicits plasticity throughout the central auditory pathway, including at the level of the medial geniculate nucleus (MGN). Hearing loss also results in altered neuronal responses in the amygdala, which is involved in sensory gating at the level of the MGN. However, whether these altered responses in the amygdala affect sensory gating at the level of the MGN requires further evaluation. The current study aimed to investigate the effects of AT-induced hearing loss on the functional connectivity between the amygdala and the MGN. Male Sprague-Dawley rats were exposed to either sham (n = 5; no sound) or AT (n = 6; 16 kHz, 1 h, 124 dB SPL) under full anaesthesia. Auditory brainstem response (ABR) recordings were made to determine hearing thresholds. Two weeks post-exposure, extracellular recordings were used to assess the effect of electrical stimulation of the amygdala on tone-evoked (sham n = 22; AT n = 30) and spontaneous (sham n = 21; AT n = 29) activity of single neurons in the MGN. AT caused a large temporary and small permanent ABR threshold shift. Electrical stimulation of the amygdala induced differential effects (excitatory, inhibitory, or no effect) on both tone-evoked and spontaneous activity. In tone-evoked activity, electrical stimulation at 300 µA, maximum current, caused a significantly larger reduction in firing rate in AT animals compared to sham, due to an increase in the magnitude of inhibitory effects. In spontaneous activity, there was also a significantly larger magnitude of inhibitory effects following AT. The findings confirm that activation of the amygdala results in changes in MGN neuronal activity, and suggest the functional connectivity between the amygdala and the MGN is significantly altered following AT and subsequent hearing loss.
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Affiliation(s)
- Jack W Zimdahl
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia.
| | - Jennifer Rodger
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia; School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia; Perron Institute for Neurological and Translational Research, Crawley, WA 6009, Australia
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Domarecka E, Szczepek AJ. Universal Recommendations on Planning and Performing the Auditory Brainstem Responses (ABR) with a Focus on Mice and Rats. Audiol Res 2023; 13:441-458. [PMID: 37366685 DOI: 10.3390/audiolres13030039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/17/2023] [Accepted: 05/29/2023] [Indexed: 06/28/2023] Open
Abstract
Translational audiology research aims to transfer basic research findings into practical clinical applications. While animal studies provide essential knowledge for translational research, there is an urgent need to improve the reproducibility of data derived from these studies. Sources of variability in animal research can be grouped into three areas: animal, equipment, and experimental. To increase standardization in animal research, we developed universal recommendations for designing and conducting studies using a standard audiological method: auditory brainstem response (ABR). The recommendations are domain-specific and are intended to guide the reader through the issues that are important when applying for ABR approval, preparing for, and conducting ABR experiments. Better experimental standardization, which is the goal of these guidelines, is expected to improve the understanding and interpretation of results, reduce the number of animals used in preclinical studies, and improve the translation of knowledge to the clinic.
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Affiliation(s)
- Ewa Domarecka
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 10117 Berlin, Germany
| | - Agnieszka J Szczepek
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, 10117 Berlin, Germany
- Faculty of Medicine and Health Sciences, University of Zielona Gora, 65-046 Zielona Gora, Poland
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Pak S, Choi G, Roy J, Poon CH, Lee J, Cho D, Lee M, Lim LW, Bao S, Yang S, Yang S. Altered synaptic plasticity of the longitudinal dentate gyrus network in noise-induced anxiety. iScience 2022; 25:104364. [PMID: 35620435 PMCID: PMC9127171 DOI: 10.1016/j.isci.2022.104364] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/31/2022] [Accepted: 05/03/2022] [Indexed: 12/20/2022] Open
Abstract
Anxiety is characteristic comorbidity of noise-induced hearing loss (NIHL), which causes physiological changes within the dentate gyrus (DG), a subfield of the hippocampus that modulates anxiety. However, which DG circuit underlies hearing loss-induced anxiety remains unknown. We utilize an NIHL mouse model to investigate short- and long-term synaptic plasticity in DG networks. The recently discovered longitudinal DG-DG network is a collateral of DG neurons synaptically connected with neighboring DG neurons and displays robust synaptic efficacy and plasticity. Furthermore, animals with NIHL demonstrate increased anxiety-like behaviors similar to a response to chronic restraint stress. These behaviors are concurrent with enhanced synaptic responsiveness and suppressed short- and long-term synaptic plasticity in the longitudinal DG-DG network but not in the transverse DG-CA3 connection. These findings suggest that DG-related anxiety is typified by synaptic alteration in the longitudinal DG-DG network. Traumatic noise-induced hearing loss enhances anxiety-like behaviors The longitudinal DG-DG network displays robust synaptic efficacy and plasticity Abnormal anxiety is associated with synaptic alterations of the DG-DG network DG-related brain disorders might stem from dysfunctional DG-DG networks
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Metabolic changes in the brain and blood of rats following acoustic trauma, tinnitus and hyperacusis. PROGRESS IN BRAIN RESEARCH 2021; 262:399-430. [PMID: 33931189 DOI: 10.1016/bs.pbr.2020.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It has been increasingly recognized that tinnitus is likely to be generated by complex network changes. Acoustic trauma that causes tinnitus induces significant changes in multiple metabolic pathways in the brain. However, it is not clear whether those metabolic changes in the brain could also be reflected in blood samples and whether metabolic changes could discriminate acoustic trauma, hyperacusis and tinnitus. We analyzed brain and serum metabolic changes in rats following acoustic trauma or a sham procedure using metabolomics. Hearing levels were recorded before and after acoustic trauma and behavioral measures to quantify tinnitus and hyperacusis were conducted at 4 weeks following acoustic trauma. Tissues from 11 different brain regions and serum samples were collected at about 3 months following acoustic trauma. Among the acoustic trauma animals, eight exhibited hyperacusis-like behavior and three exhibited tinnitus-like behavior. Using Gas chromatography-mass spectrometry and multivariate statistical analysis, significant metabolic changes were found in acoustic trauma animals in both the brain and serum samples with a number of metabolic pathways significantly perturbated. Furthermore, metabolic changes in the serum were able to differentiate sham from acoustic trauma animals, as well as sham from hyperacusis animals, with high accuracy. Our results suggest that serum metabolic profiling in combination with machine learning analysis may be a promising approach for identifying biomarkers for acoustic trauma, hyperacusis and potentially, tinnitus.
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Narwani V, Bourdillon A, Nalamada K, Manes RP, Hildrew DM. Does cannabis alleviate tinnitus? A review of the current literature. Laryngoscope Investig Otolaryngol 2020; 5:1147-1155. [PMID: 33364406 PMCID: PMC7752070 DOI: 10.1002/lio2.479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/07/2020] [Accepted: 10/10/2020] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES Endocannabinoid pathways have been proposed to affect the underlying pathophysiology of tinnitus. The aim of this study is to evaluate the scope and findings of existing literature on the relationship between cannabis and cannabinoid pathways and tinnitus. METHODS We conducted a review of animal, clinical and survey studies investigating the relationship between the use of cannabis-derived agents and tinnitus. Using pertinent keywords and MeSH terms on PubMed, relevant studies were identified, yielding four animal studies, two large cross-sectional survey studies, one clinical cross-over study, and one case report. RESULTS Animal studies revealed that cannabinoid receptor expression in the cochlear nucleus varied with tinnitus symptomatology and the use of cannabinoid agents either increased or had no effect on tinnitus-related behavior. Survey studies yielded conflicting results between cannabis use and tinnitus in the general population. Clinical data is largely lacking, although a small cohort study showed a dose-dependent relationship between tetrahydrocannabinol consumption and frequency of tinnitus episodes in patients receiving treatment for cancer. CONCLUSION While animal studies have revealed that cannabinoid receptors likely have a role in modulating auditory signaling, there is no compelling data either from animal or human studies for the use of cannabinoids to alleviate tinnitus. Further research is necessary to elucidate their precise role to guide development of therapeutic interventions. LEVEL OF EVIDENCE NA.
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Affiliation(s)
- Vishal Narwani
- Division of Otolaryngology – Head and Neck Surgery, Department of SurgeryYale University School of MedicineNew HavenConnecticutUSA
| | | | - Keerthana Nalamada
- Department of NeurologyUniversity of ConnecticutFarmingtonConnecticutUSA
| | - R. Peter Manes
- Division of Otolaryngology – Head and Neck Surgery, Department of SurgeryYale University School of MedicineNew HavenConnecticutUSA
| | - Douglas M. Hildrew
- Division of Otolaryngology – Head and Neck Surgery, Department of SurgeryYale University School of MedicineNew HavenConnecticutUSA
- Division of Otolaryngology – Head and Neck Surgery, Department of SurgeryVA Connecticut Healthcare SystemWest HavenConnecticutUSA
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Domarecka E, Olze H, Szczepek AJ. Auditory Brainstem Responses (ABR) of Rats during Experimentally Induced Tinnitus: Literature Review. Brain Sci 2020; 10:brainsci10120901. [PMID: 33255266 PMCID: PMC7760291 DOI: 10.3390/brainsci10120901] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/16/2020] [Accepted: 11/21/2020] [Indexed: 12/31/2022] Open
Abstract
Tinnitus is a subjective phantom sound perceived only by the affected person and a symptom of various auditory and non-auditory conditions. The majority of methods used in clinical and basic research for tinnitus diagnosis are subjective. To better understand tinnitus-associated changes in the auditory system, an objective technique measuring auditory sensitivity-the auditory brainstem responses (ABR)-has been suggested. Therefore, the present review aimed to summarize ABR's features in a rat model during experimentally induced tinnitus. PubMed, Web of Science, Science Direct, and Scopus databanks were searched using Medical Subject Heading (MeSH) terms: auditory brainstem response, tinnitus, rat. The search identified 344 articles, and 36 of them were selected for the full-text analyses. The experimental protocols and results were evaluated, and the gained knowledge was synthesized. A high level of heterogeneity between the studies was found regarding all assessed areas. The most consistent finding of all studies was a reduction in the ABR wave I amplitude following exposure to noise and salicylate. Simultaneously, animals with salicylate-induced but not noise-induced tinnitus had an increased amplitude of wave IV. Furthermore, the present study identified a need to develop a consensus experimental ABR protocol applied in future tinnitus studies using the rat model.
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Affiliation(s)
- Ewa Domarecka
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (E.D.); (H.O.)
| | - Heidi Olze
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (E.D.); (H.O.)
| | - Agnieszka J. Szczepek
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (E.D.); (H.O.)
- Faculty of Medicine and Health Sciences, University of Zielona Gora, 65-046 Zielona Gora, Poland
- Correspondence:
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Abstract
Tinnitus is a common symptom. Standard therapies aim at improving the quality of life and reducing the psychological stress associated with tinnitus. Most interventions have little or no effect on the main symptom. Those affected subjects, however, want such a change and prefer a specific solution, such as pharmacologic therapy to other modalities. Scientific efforts have not yet led to significant improvement in the range of therapies. This article outlines existing efforts and develops ideas on how research for improved tinnitus therapy might look in the future.
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Affiliation(s)
- Tobias Kleinjung
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 24, Zurich CH 8091, Switzerland.
| | - Berthold Langguth
- Department of Psychiatry and Psychotherapy, Interdisciplinary Tinnitus Center, University of Regensburg, Universitätsstrasse 84, Regensburg D 93053, Germany
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9
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Winne J, Boerner BC, Malfatti T, Brisa E, Doerl J, Nogueira I, Leão KE, Leão RN. Anxiety-like behavior induced by salicylate depends on age and can be prevented by a single dose of 5-MeO-DMT. Exp Neurol 2020; 326:113175. [PMID: 31923390 DOI: 10.1016/j.expneurol.2020.113175] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/23/2019] [Accepted: 01/06/2020] [Indexed: 11/16/2022]
Abstract
Salicylate intoxication is a cause of tinnitus and comorbidly associated with anxiety in humans. In a previous work, we showed that salicylate induces anxiety-like behavior and hippocampal type 2 theta oscillations (theta2) in mice. Here we investigate if the anxiogenic effect of salicylate is dependent on age and previous tinnitus experience. We also tested whether a single dose of DMT can prevent this effect. Using microwire electrode arrays, we recorded local field potential in young (4-5- month-old) and old (11-13-month-old) mice to study the electrophysiological effect of tinnitus in the ventral hippocampus (vHipp) and medial prefrontal cortex (mPFC) in an open field arena and elevated plus maze 1h after salicylate (300mg/kg) injection. We found that anxiety-like behavior and increase in theta2 oscillations (4-6 Hz), following salicylate pre-treatment, only occurs in young (normal hearing) mice. We also show that theta2 and slow gamma oscillations increase in the vHipp and mPFC in a complementary manner during anxiety tests in the presence of salicylate. Finally, we show that pre-treating mice with a single dose of the hallucinogenic 5-MeO-DMT prevents anxiety-like behavior and the increase in theta2 and slow gamma oscillations after salicylate injection in normal hearing young mice. This work further support the hypothesis that anxiety-like behavior after salicylate injection is triggered by tinnitus and require normal hearing. Moreover, our results show that hallucinogenic compounds can be effective in treating tinnitus-related anxiety.
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Affiliation(s)
- Jessica Winne
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil; Developmental Genetics Unit, Department of Neuroscience, Uppsala University, Husarg 3, Uppsala 75234, Sweden
| | - Barbara C Boerner
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil
| | - Thawann Malfatti
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil
| | - Elis Brisa
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil
| | - Jhulimar Doerl
- Neural Development and Environment Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal, RN, Brazil
| | - Ingrid Nogueira
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil
| | - Katarina E Leão
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil
| | - Richardson N Leão
- Neurodynamics Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal/RN, Brazil; Neural Development and Environment Lab, Brain Institute, Federal University of the Rio Grande do Norte, Av. Nascimento de Castro 2155, 59560-450 Natal, RN, Brazil.
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10
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Zheng Y, McTavish J, Smith PF. Pharmacological Evaluation of Drugs in Animal Models of Tinnitus. Curr Top Behav Neurosci 2020; 51:51-82. [PMID: 33590458 DOI: 10.1007/7854_2020_212] [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: 12/24/2022]
Abstract
Despite the pressing need for effective drug treatments for tinnitus, currently, there is no single drug that is approved by the FDA for this purpose. Instead, a wide range of unproven over-the-counter tinnitus remedies are available on the market with little or no benefit for tinnitus but with potential harm and adverse effects. Animal models of tinnitus have played a critical role in exploring the pathophysiology of tinnitus, identifying therapeutic targets and evaluating novel and existing drugs for tinnitus treatment. This review summarises and compares the studies on pharmacological evaluation of tinnitus treatment in different animal models based on the pharmacological properties of the drug and provides insights into future directions for tinnitus drug discovery.
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Affiliation(s)
- Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand. .,Brain Research New Zealand, Auckland, New Zealand. .,Brain Health Research Centre, University of Otago, Dunedin, New Zealand. .,Eisdell Moore Centre for Hearing and Balance Research, University of Auckland, Auckland, New Zealand.
| | - Jessica McTavish
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Research New Zealand, Auckland, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Eisdell Moore Centre for Hearing and Balance Research, University of Auckland, Auckland, New Zealand
| | - Paul F Smith
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Research New Zealand, Auckland, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Eisdell Moore Centre for Hearing and Balance Research, University of Auckland, Auckland, New Zealand
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11
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Zhang J. Blast-induced tinnitus: Animal models. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3811. [PMID: 31795642 DOI: 10.1121/1.5132551] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Blast-induced tinnitus is a prevalent problem among military personnel and veterans, as blast-related trauma damages the vulnerable microstructures within the cochlea, impacts auditory and non-auditory brain structures, and causes tinnitus and other disorders. Thus far, there is no effective treatment of blast-induced tinnitus due to an incomplete understanding of its underlying mechanisms, necessitating development of reliable animal models. This article focuses on recent animal studies using behavioral, electrophysiological, imaging, and pharmacological tools. The mechanisms underlying blast-induced tinnitus are largely similar to those underlying noise-induced tinnitus: increased spontaneous firing rates, bursting, and neurosynchrony, Mn++ accumulation, and elevated excitatory synaptic transmission. The differences mainly lie in the data variability and time course. Noise trauma-induced tinnitus mainly originates from direct peripheral deafferentation at the cochlea, and its etiology subsequently develops along the ascending auditory pathways. Blast trauma-induced tinnitus, on the other hand, results from simultaneous impact on both the peripheral and central auditory systems, and the resultant maladaptive neuroplasticity may also be related to the additional traumatic brain injury. Consequently, the neural correlates of blast-induced tinnitus have different time courses and less uniform manifestations of its neural correlates.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, 4201 Saint Antoine, Detroit, Michigan 48201, USA
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12
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Holt AG, Kühl A, Braun RD, Altschuler R. The rat as a model for studying noise injury and otoprotection. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3681. [PMID: 31795688 DOI: 10.1121/1.5131344] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A major challenge for those studying noise-induced injury pre-clinically is the selection of an animal model. Noise injury models are particularly relevant in an age when people are constantly bombarded by loud noise due to occupation and/or recreation. The rat has been widely used for noise-related morphological, physiological, biochemical, and molecular assessment. Noise exposure resulting in a temporary (TTS) or permanent threshold shift (PTS) yields trauma in peripheral and central auditory related pathways. While the precise nature of noise-related injuries continues to be delineated, both PTS and TTS (with or without hidden hearing loss) result in homeostatic changes implicated in conditions such as tinnitus and hyperacusis. Compared to mice, rats generally tolerate exposure to loud sounds reasonably well, often without exhibiting other physical non-inner ear related symptoms such as death, loss of consciousness, or seizures [Skradski, Clark, Jiang, White, Fu, and Ptacek (2001). Neuron 31, 537-544; Faingold (2002). Hear. Res. 168, 223-237; Firstova, Abaimov, Surina, Poletaeva, Fedotova, and Kovalev (2012). Bull Exp. Biol. Med. 154, 196-198; De Sarro, Russo, Citraro, and Meldrum (2017). Epilepsy Behav. 71, 165-173]. This ability of the rat to thrive following noise exposure permits study of long-term effects. Like the mouse, the rat also offers a well-characterized genome allowing genetic manipulations (i.e., knock-out, viral-based gene expression modulation, and optogenetics). Rat models of noise-related injury also provide valuable information for understanding mechanistic changes to identify therapeutic targets for treatment. This article provides a framework for selection of the rat as a model for noise injury studies.
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Affiliation(s)
- Avril Genene Holt
- Department of Ophthalmology, Visual, and Anatomical Sciences (OVAS), School of Medicine, Wayne State University, 550 East Canfield Avenue, 454 Lande Building, Detroit, Michigan 48201, USA
| | - André Kühl
- Department of Ophthalmology, Visual, and Anatomical Sciences (OVAS), School of Medicine, Wayne State University, 550 East Canfield Avenue, 454 Lande Building, Detroit, Michigan 48201, USA
| | - Rod D Braun
- Department of Ophthalmology, Visual, and Anatomical Sciences (OVAS), School of Medicine, Wayne State University, 550 East Canfield Avenue, 454 Lande Building, Detroit, Michigan 48201, USA
| | - Richard Altschuler
- Department of Otolaryngology; Cell and Developmental Biology, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA
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13
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Langguth B, Elgoyhen AB, Cederroth CR. Therapeutic Approaches to the Treatment of Tinnitus. Annu Rev Pharmacol Toxicol 2019; 59:291-313. [DOI: 10.1146/annurev-pharmtox-010818-021556] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tinnitus is a highly prevalent condition that is associated with hearing loss in most cases. In the absence of external stimuli, phantom perceptions of sounds emerge from alterations in neuronal activity within central auditory and nonauditory structures. Pioneering studies using lidocaine revealed that tinnitus is susceptible to pharmacological interventions. However, lidocaine is not effective in all patients, and no other drug has been identified with clear efficacy for the long-term treatment of tinnitus. In this review, we present recent advances in tinnitus research, including more detailed knowledge of its pathophysiology and involved neurotransmitter systems. Moreover, we summarize results from animal and clinical treatment studies as well as from studies that identified tinnitus as a side effect of pharmacological treatments. Finally, we focus on challenges in the development of pharmacological compounds for the treatment of tinnitus, namely the limitations of available animal models and of standardized clinical research methodologies.
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Affiliation(s)
- Berthold Langguth
- Department of Psychiatry and Psychotherapy, and Interdisciplinary Tinnitus Clinic, University of Regensburg, 93053 Regensburg, Germany
| | - Ana Belen Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres,” Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires, Argentina
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, 1121 Buenos Aires, Argentina
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Swords GM, Nguyen LT, Mudar RA, Llano DA. Auditory system dysfunction in Alzheimer disease and its prodromal states: A review. Ageing Res Rev 2018; 44:49-59. [PMID: 29630950 DOI: 10.1016/j.arr.2018.04.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 01/15/2023]
Abstract
Recent findings suggest that both peripheral and central auditory system dysfunction occur in the prodromal stages of Alzheimer Disease (AD), and therefore may represent early indicators of the disease. In addition, loss of auditory function itself leads to communication difficulties, social isolation and poor quality of life for both patients with AD and their caregivers. Developing a greater understanding of auditory dysfunction in early AD may shed light on the mechanisms of disease progression and carry diagnostic and therapeutic importance. Herein, we review the literature on hearing abilities in AD and its prodromal stages investigated through methods such as pure-tone audiometry, dichotic listening tasks, and evoked response potentials. We propose that screening for peripheral and central auditory dysfunction in at-risk populations is a low-cost and effective means to identify early AD pathology and provides an entry point for therapeutic interventions that enhance the quality of life of AD patients.
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Affiliation(s)
| | - Lydia T Nguyen
- Neuroscience Program, University of Illinois at Urbana-Champaign, United States; Department of Speech and Hearing Science, University of Illinois at Urbana-Champaign, United States
| | - Raksha A Mudar
- Neuroscience Program, University of Illinois at Urbana-Champaign, United States; Department of Speech and Hearing Science, University of Illinois at Urbana-Champaign, United States
| | - Daniel A Llano
- University of Illinois College of Medicine, United States; Neuroscience Program, University of Illinois at Urbana-Champaign, United States; Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, United States; Beckman Institute for Advanced Science and Technology, Urbana, IL, United States.
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15
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Behavioral Animal Model of the Emotional Response to Tinnitus and Hearing Loss. J Assoc Res Otolaryngol 2017; 19:67-81. [PMID: 29047013 DOI: 10.1007/s10162-017-0642-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 09/28/2017] [Indexed: 12/28/2022] Open
Abstract
Increased prevalence of emotional distress is associated with tinnitus and hearing loss. The underlying mechanisms of the negative emotional response to tinnitus and hearing loss remain poorly understood, and it is challenging to disentangle the emotional consequences of hearing loss from those specific to tinnitus in listeners experiencing both. We addressed these questions in laboratory rats using three common rodent anxiety screening assays: elevated plus maze, open field test, and social interaction test. Open arm activity in the elevated plus maze decreased substantially after one trial in controls, indicating its limited utility for comparing pre- and post-treatment behavior. Open field exploration and social interaction behavior were consistent across multiple sessions in control animals. Individual sound-exposed and salicylate-treated rats showed a range of phenotypes in the open field, including reduced entries into the center in some subjects and reduced locomotion overall. In rats screened for tinnitus, less locomotion was associated with higher tinnitus scores. In salicylate-treated animals, locomotion was correlated with age. Sound-exposed and salicylate-treated rats also showed reduced social interaction. These results suggest that open field exploratory activity is a selective measure for identifying tinnitus distress in individual animals, whereas social interaction reflects the general effects of hearing loss. This animal model will facilitate future studies of the structural and functional changes in the brain pathways underlying emotional distress associated with hearing dysfunction, as well as development of novel interventions to ameliorate or prevent negative emotional responses.
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16
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Ouyang J, Pace E, Lepczyk L, Kaufman M, Zhang J, Perrine SA, Zhang J. Blast-Induced Tinnitus and Elevated Central Auditory and Limbic Activity in Rats: A Manganese-Enhanced MRI and Behavioral Study. Sci Rep 2017; 7:4852. [PMID: 28687812 PMCID: PMC5501813 DOI: 10.1038/s41598-017-04941-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 04/27/2017] [Indexed: 02/06/2023] Open
Abstract
Blast-induced tinitus is the number one service-connected disability that currently affects military personnel and veterans. To elucidate its underlying mechanisms, we subjected 13 Sprague Dawley adult rats to unilateral 14 psi blast exposure to induce tinnitus and measured auditory and limbic brain activity using manganese-enhanced MRI (MEMRI). Tinnitus was evaluated with a gap detection acoustic startle reflex paradigm, while hearing status was assessed with prepulse inhibition (PPI) and auditory brainstem responses (ABRs). Both anxiety and cognitive functioning were assessed using elevated plus maze and Morris water maze, respectively. Five weeks after blast exposure, 8 of the 13 blasted rats exhibited chronic tinnitus. While acoustic PPI remained intact and ABR thresholds recovered, the ABR wave P1-N1 amplitude reduction persisted in all blast-exposed rats. No differences in spatial cognition were observed, but blasted rats as a whole exhibited increased anxiety. MEMRI data revealed a bilateral increase in activity along the auditory pathway and in certain limbic regions of rats with tinnitus compared to age-matched controls. Taken together, our data suggest that while blast-induced tinnitus may play a role in auditory and limbic hyperactivity, the non-auditory effects of blast and potential traumatic brain injury may also exert an effect.
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Affiliation(s)
- Jessica Ouyang
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Edward Pace
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Laura Lepczyk
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Michael Kaufman
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Jessica Zhang
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Shane A Perrine
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Jinsheng Zhang
- Department of Otolaryngology and Head and Neck Surgery, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
- Department of Communication Sciences & Disorders, Wayne State University College of Liberal Arts and Sciences, Detroit, MI, 48201, USA.
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17
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Elgoyhen AB, Langguth B, De Ridder D, Vanneste S. Tinnitus: perspectives from human neuroimaging. Nat Rev Neurosci 2015; 16:632-42. [DOI: 10.1038/nrn4003] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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18
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Zhang J, Luo H, Pace E, Li L, Liu B. Psychophysical and neural correlates of noised-induced tinnitus in animals: Intra- and inter-auditory and non-auditory brain structure studies. Hear Res 2015; 334:7-19. [PMID: 26299842 DOI: 10.1016/j.heares.2015.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 08/04/2015] [Accepted: 08/17/2015] [Indexed: 12/19/2022]
Abstract
Tinnitus, a ringing in the ear or head without an external sound source, is a prevalent health problem. It is often associated with a number of limbic-associated disorders such as anxiety, sleep disturbance, and emotional distress. Thus, to investigate tinnitus, it is important to consider both auditory and non-auditory brain structures. This paper summarizes the psychophysical, immunocytochemical and electrophysiological evidence found in rats or hamsters with behavioral evidence of tinnitus. Behaviorally, we tested for tinnitus using a conditioned suppression/avoidance paradigm, gap detection acoustic reflex behavioral paradigm, and our newly developed conditioned licking suppression paradigm. Our new tinnitus behavioral paradigm requires relatively short baseline training, examines frequency specification of tinnitus perception, and achieves sensitive tinnitus testing at an individual level. To test for tinnitus-related anxiety and cognitive impairment, we used the elevated plus maze and Morris water maze. Our results showed that not all animals with tinnitus demonstrate anxiety and cognitive impairment. Immunocytochemically, we found that animals with tinnitus manifested increased Fos-like immunoreactivity (FLI) in both auditory and non-auditory structures. The manner in which FLI appeared suggests that lower brainstem structures may be involved in acute tinnitus whereas the midbrain and cortex are involved in more chronic tinnitus. Meanwhile, animals with tinnitus also manifested increased FLI in non-auditory brain structures that are involved in autonomic reactions, stress, arousal and attention. Electrophysiologically, we found that rats with tinnitus developed increased spontaneous firing in the auditory cortex (AC) and amygdala (AMG), as well as intra- and inter-AC and AMG neurosynchrony, which demonstrate that tinnitus may be actively produced and maintained by the interactions between the AC and AMG.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA; Department of Communication Sciences & Disorders, Wayne State University, College of Liberal Arts & Sciences, 60 Farnsworth St., Detroit, MI 48202, USA.
| | - Hao Luo
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
| | - Edward Pace
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
| | - Liang Li
- Department of Psychology, McGovern Institute for Brain Research at PKU, Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing, 100080, China
| | - Bin Liu
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
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19
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Zheng Y, Smithies H, Aitken P, Gliddon C, Stiles L, Darlington CL, Smith PF. Cell proliferation in the cochlear nucleus following acoustic trauma in rat. Neuroscience 2015; 303:524-34. [PMID: 26192094 DOI: 10.1016/j.neuroscience.2015.07.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/08/2015] [Accepted: 07/10/2015] [Indexed: 01/21/2023]
Abstract
Our previous studies have suggested that surgical lesions of the rat cochlea induce cell proliferation in the cochlear nucleus (CN) that may be related to neurogenesis. The aim of the present study was to further investigate the nature of cell proliferation in the CN, following acoustic trauma that has previously been shown to induce tinnitus in rats. Rats were subjected either to a unilateral acoustic trauma (16-kHz pure tone, 115dB for 1h under anesthesia) or a sham procedure. Bromodeoxyuridine (BrdU) immunohistochemistry was used to measure cell proliferation and newborn cell survival; an antibody to interleukin-6 was used to investigate inflammatory responses; and double immunolabeling for BrdU and Ki-67, BrdU and CD-11b, and BrdU and doublecortin (DCX), was used to investigate the origin of the proliferating cells. There was a time-dependent increase in the number of BrdU(+ve) cells in the CN following acoustic trauma; however, the number of BrdU(+ve) cells that survived was comparable to that of control animals at 4 weeks post-trauma. Cell proliferation was unlikely to be due to proliferating inflammatory cells as a result of a trauma-induced inflammatory response as the IL-6 expression level was comparable between sham and exposed groups. Immunolabeling revealed the BrdU(+ve) cells to co-express Ki-67 and DCX, but not CD-11b. However, there was no difference in DCX expression between sham and exposed animals. The results suggest that DCX-expressing cells in the CN may proliferate in response to acoustic trauma; however, the proportion of cells proliferating and the survival rate of the newborn cells may not support functional neurogenesis in the CN.
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Affiliation(s)
- Y Zheng
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
| | - H Smithies
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - P Aitken
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - C Gliddon
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - L Stiles
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - C L Darlington
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - P F Smith
- Dept. of Pharmacology and Toxicology, School of Medical Sciences and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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20
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Han L, Zhaohui L, Fei Y, Pengfei Z, Ting L, Cheng D, Zhenchang W. Disrupted neural activity in unilateral vascular pulsatile tinnitus patients in the early stage of disease: evidence from resting-state fMRI. Prog Neuropsychopharmacol Biol Psychiatry 2015; 59:91-99. [PMID: 25645870 DOI: 10.1016/j.pnpbp.2015.01.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/20/2015] [Accepted: 01/23/2015] [Indexed: 02/07/2023]
Abstract
Numerous studies have shown that neurological changes are important findings of tinnitus patients. Previous studies on tinnitus have indicated that patients with pulsatile tinnitus (PT) often show altered baseline brain activity in the resting state. This study used resting-state functional magnetic resonance imaging (rs-fMRI) to investigate changes in spontaneous brain activity among patients with unilateral pulsatile tinnitus in the early stage of disease (less than forty-eight months) and determined the relationship of these changes with clinical data. The PT patients (n=34) and matched normal control subjects (n=34) were enrolled in this study. Spontaneous brain activity was revealed by the regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) values. Compared with normal controls, the patients with PT had significantly increased ReHo and ALFF in the posterior cingulate cortex, right inferior parietal lobule (IPL) and right cerebellum posterior lobe. The PT group showed increased ReHo in the posterior cingulate cortex (PCC), precuneus, right IPL, right superior frontal gyrus, some occipital areas and part of the right cerebellum posterior lobe. For ALFF, the increased clusters were in the PCC and precuneus and in some areas of the cerebellum posterior lobe, bilateral IPL and inferior frontal gyrus (IFG). Increased PT duration was correlated with increased ALFF in the bilateral inferior frontal gyrus (IFG) and precuneus. An increased THI score was correlated with ReHo and ALFF values in the precuneus. Taken together, the combined study of ReHo and ALFF measurements may yield a more comprehensive neurological pathophysiology framework for PT patients in the early stage of the disease.
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Affiliation(s)
- Lv Han
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Liu Zhaohui
- Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Yan Fei
- Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Zhao Pengfei
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Li Ting
- Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Dong Cheng
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Wang Zhenchang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
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21
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Zheng Y, McPherson K, Reid P, Smith PF. The anti-inflammatory selective melanocortin receptor subtype 4 agonist, RO27-3225, fails to prevent acoustic trauma-induced tinnitus in rats. Eur J Pharmacol 2015; 761:206-10. [PMID: 25977231 DOI: 10.1016/j.ejphar.2015.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/06/2015] [Accepted: 05/11/2015] [Indexed: 10/23/2022]
Abstract
In preliminary studies we have observed a massive microglial activation in the cochlear nucleus following acoustic trauma-induced tinnitus in rats, which suggests that inflammatory responses within the central auditory system may be involved in the development and maintenance of tinnitus. Recently, the anti-inflammatory properties of melanocortins (MCs), have gained increasing interest in pharmacology due to their promising therapeutic potential in the treatment of inflammatory-mediated diseases. Among the five subtypes of the MC receptor, MC3 and MC4 receptors are the predominant brain receptors and are thought to play an important role in brain inflammation and neuroprotection. Importantly, MC4 receptors have been found in the mouse and rat central auditory systems. In this study we investigated whether the MC4 receptor agonist, RO27-3225, injected s.c at a dose of 90 or 180µg/kg, 30min before acoustic trauma and then every 12h for 10 days, could prevent the development of acoustic trauma-induced tinnitus in rats, using a conditioned behavioural suppression model. Although evidence of tinnitus developed in the exposed-vehicle group compared to the sham-vehicle group (P≤0.03), in response to a 32kHz tone, there were no significant drug effects from treatment with RO27-3225, indicating that it did not confer any protection against the development of tinnitus in this animal model. This result suggests that the anti-inflammatory effects of MC4 receptor agonists may not be sufficient to prevent tinnitus.
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Affiliation(s)
- Yiwen Zheng
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
| | - Kate McPherson
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Peter Reid
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Paul F Smith
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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22
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Zheng Y, Reid P, Smith PF. Cannabinoid CB1 Receptor Agonists Do Not Decrease, but may Increase Acoustic Trauma-Induced Tinnitus in Rats. Front Neurol 2015; 6:60. [PMID: 25852639 PMCID: PMC4364172 DOI: 10.3389/fneur.2015.00060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/05/2015] [Indexed: 11/13/2022] Open
Abstract
Tinnitus has been suggested to arise from neuronal hyperactivity in auditory areas of the brain, and anti-epileptic drugs are sometimes used to provide relief from tinnitus. Recently, the anti-epileptic properties of the cannabinoid drugs have gained increasing interest; however, the use of cannabinoids as a form of treatment for tinnitus is controversial. In this study, we tested whether a combination of delta-9-tetrahydrocannabinol (delta-9-THC) and cannabidiol (CBD), delivered in a 1:1 ratio, could affect tinnitus perception in a rat model of acoustic trauma-induced tinnitus. Following sham treatment or acoustic trauma, the animals were divided into the following groups: (1) sham (i.e., no acoustic trauma) with vehicle treatment; (2) sham with drug treatment (i.e., delta-9-THC + CBD); (3) acoustic trauma-exposed exhibiting tinnitus, with drug treatment; and (4) acoustic trauma-exposed exhibiting no tinnitus, with drug treatment. The animals received either the vehicle or the cannabinoid drugs every day, 30 min before the tinnitus behavioral testing. Acoustic trauma caused a significant increase in the auditory brainstem response (ABR) thresholds in the exposed animals, indicating hearing loss; however, there was a partial recovery over 6 months. Acoustic trauma did not always result in tinnitus; however, among those that did exhibit tinnitus, some of them had tinnitus at multiple frequencies while others had it only at a single frequency. The cannabinoids significantly increased the number of tinnitus animals in the exposed-tinnitus group, but not in the sham group. The results suggest that cannabinoids may promote the development of tinnitus, especially when there is pre-existing hearing damage.
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Affiliation(s)
- Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago , Dunedin , New Zealand ; Brain Health Research Centre, School of Medical Sciences, University of Otago , Dunedin , New Zealand
| | - Peter Reid
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago , Dunedin , New Zealand ; Brain Health Research Centre, School of Medical Sciences, University of Otago , Dunedin , New Zealand
| | - Paul F Smith
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago , Dunedin , New Zealand ; Brain Health Research Centre, School of Medical Sciences, University of Otago , Dunedin , New Zealand
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23
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Heeringa AN, Agterberg MJH, van Dijk P. Spontaneous behavior in noise and silence: a possible new measure to assess tinnitus in Guinea pigs. Front Neurol 2014; 5:207. [PMID: 25360130 PMCID: PMC4197645 DOI: 10.3389/fneur.2014.00207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 09/30/2014] [Indexed: 12/20/2022] Open
Abstract
This study describes two experiments that were conducted in search for a behavioral paradigm to test for tinnitus in guinea pigs. Conditioning paradigms are available to determine the presence of tinnitus in animals and are based on the assumption that tinnitus impairs their ability to detect silent intervals in continuous noise. Guinea pigs have not been subjected to these paradigms yet; therefore, we investigated whether guinea pigs could be conditioned in the two-way shuttle-box paradigm to respond to silent intervals in noise. Even though guinea pigs could be trained relatively easy to respond to the presence of a noise interval, training guinea pigs to silent intervals in noise was unsuccessful. Instead, it appeared that they became immobile when the continuous stimulus was suddenly stopped. This was confirmed by the next experiment, in which we subjected guinea pigs to alternating intervals of noise and silence with a random duration between 30 and 120 s. Indeed, guinea pigs were significantly longer immobile during silence compared to during noise. By interpreting immobility as a signature of perceiving silence, we hypothesized that the presence of tinnitus would reduce immobility in silence. Therefore, we unilaterally exposed one group of guinea pigs to an 11-kHz tone of 124 dB sound pressure level for 1 h. A subset of the exposed animals was significantly more active in silence, but also more active in noise, as compared to the control group. The increased mobility during silent intervals might represent tinnitus. However, the increased mobility in noise of this group implies that the observed behavior could have derived from, e.g., an overall increase in activity. Therefore, conducting validation experiments is very important before implementing this method as a new screening tool for tinnitus. Follow-up experiments are discussed to further elucidate the origin of the increased mobility in both silence and noise.
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Affiliation(s)
- Amarins N Heeringa
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen , Groningen , Netherlands ; Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen , Groningen , Netherlands
| | - Martijn J H Agterberg
- Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre , Nijmegen , Netherlands ; Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen , Nijmegen , Netherlands
| | - Pim van Dijk
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen , Groningen , Netherlands ; Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen , Groningen , Netherlands
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24
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The effects of acute stress-induced sleep disturbance on acoustic trauma-induced tinnitus in rats. BIOMED RESEARCH INTERNATIONAL 2014; 2014:724195. [PMID: 25162023 PMCID: PMC4137606 DOI: 10.1155/2014/724195] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/03/2014] [Indexed: 11/18/2022]
Abstract
Chronic tinnitus is a debilitating condition and often accompanied by anxiety, depression, and sleep disturbance. It has been suggested that sleep disturbance, such as insomnia, may be a risk factor/predictor for tinnitus-related distress and the two conditions may share common neurobiological mechanisms. This study investigated whether acute stress-induced sleep disturbance could increase the susceptibility to acoustic trauma-induced tinnitus in rats. The animals were exposed to unilateral acoustic trauma 24 h before sleep disturbance being induced using the cage exchange method. Tinnitus perception was assessed behaviourally using a conditioned lick suppression paradigm 3 weeks after the acoustic trauma. Changes in the orexin system in the hypothalamus, which plays an important role in maintaining long-lasting arousal, were also examined using immunohistochemistry. Cage exchange resulted in a significant reduction in the number of sleep episodes and acoustic trauma-induced tinnitus with acoustic features similar to a 32 kHz tone at 100 dB. However, sleep disturbance did not exacerbate the perception of tinnitus in rats. Neither tinnitus alone nor tinnitus plus sleep disturbance altered the number of orexin-expressing neurons. The results suggest that acute sleep disturbance does not cause long-term changes in the number of orexin neurons and does not change the perception of tinnitus induced by acoustic trauma in rats.
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Abstract
Tinnitus is one of the major audiological diseases, affecting a significant portion of the ageing society. Despite its huge personal and presumed economic impact there are only limited therapeutic options available. The reason for this deficiency lies in the very nature of the disease as it is deeply connected to elementary plasticity of auditory processing in the central nervous system. Understanding these mechanisms is essential for developing a therapy that reverses the plastic changes underlying the pathogenesis of tinnitus. This requires experiments that address individual neurons and small networks, something usually not feasible in human patients. However, in animals such invasive experiments on the level of single neurons with high spatial and temporal resolution are possible. Therefore, animal models are a very critical element in the combined efforts for engineering new therapies. This review provides an overview over the most important features of animal models of tinnitus: which laboratory species are suitable, how to induce tinnitus, and how to characterize the perceived tinnitus by behavioral means. In particular, these aspects of tinnitus animal models are discussed in the light of transferability to the human patients.
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Combining transcranial direct current stimulation and tailor-made notched music training to decrease tinnitus-related distress--a pilot study. PLoS One 2014; 9:e89904. [PMID: 24587113 PMCID: PMC3934956 DOI: 10.1371/journal.pone.0089904] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 01/25/2014] [Indexed: 11/19/2022] Open
Abstract
The central auditory system has a crucial role in tinnitus generation and maintenance. Curative treatments for tinnitus do not yet exist. However, recent attempts in the therapeutic application of both acoustic stimulation/training procedures and electric/magnetic brain stimulation techniques have yielded promising results. Here, for the first time we combined tailor-made notched music training (TMNMT) with transcranial direct current stimulation (tDCS) in an effort to modulate TMNMT efficacy in the treatment of 32 patients with tonal tinnitus and without severe hearing loss. TMNMT is characterized by regular listening to so-called notched music, which is generated by digitally removing the frequency band of one octave width centered at the individual tinnitus frequency. TMNMT was applied for 10 subsequent days (2.5 hours of daily treatment). During the initial 5 days of treatment and the initial 30 minutes of TMNMT sessions, tDCS (current strength: 2 mA; anodal (N = 10) vs. cathodal (N = 11) vs. sham (N = 11) groups) was applied simultaneously. The active electrode was placed on the head surface over left auditory cortex; the reference electrode was put over right supra-orbital cortex. To evaluate treatment outcome, tinnitus-related distress and perceived tinnitus loudness were assessed using standardized tinnitus questionnaires and a visual analogue scale. The results showed a significant treatment effect reflected in the Tinnitus Handicap Questionnaire that was largest after 5 days of treatment. This effect remained significant at the end of follow-up 31 days after treatment cessation. Crucially, tDCS did not significantly modulate treatment efficacy - it did not make a difference whether anodal, cathodal, or sham tDCS was applied. Possible explanations for the findings and functional modifications of the experimental design for future studies (e.g. the selection of control conditions) are discussed.
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27
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Zheng Y, McPherson K, Smith PF. Effects of early and late treatment with L-baclofen on the development and maintenance of tinnitus caused by acoustic trauma in rats. Neuroscience 2013; 258:410-21. [PMID: 24291770 DOI: 10.1016/j.neuroscience.2013.11.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 11/01/2013] [Accepted: 11/18/2013] [Indexed: 10/26/2022]
Abstract
Subjective tinnitus is a chronic neurological disorder in which phantom sounds are perceived. Recent evidence supports the hypothesis that tinnitus is related to neuronal hyperactivity in auditory brain regions, and consequently drugs that increase GABAergic neurotransmission in the CNS, such as the GABA(B) receptor agonist L-baclofen, may be effective as a treatment. The aim of this study was to investigate the effects of early (5 mg/kg s.c., 30 min and then every 24 h for 5 days following noise exposure) and late treatment (3 mg/kg/day s.c. for 4.5 weeks starting at 17.5 weeks following noise exposure) with l-baclofen on the psychophysical attributes of tinnitus in a conditioned lick suppression model following acoustic trauma in rats. Acoustic trauma (a 16-kHz, 115-dB pure tone presented unilaterally for 1h) resulted in a significant decrease in the suppression ratio (SR) compared to sham controls in response to 20-kHz tones at 2, 10 and 17.5 weeks post-exposure (P ≤ 0.009, P ≤ 0.02 and P ≤ 0.03, respectively). However, l-baclofen failed to prevent the development of tinnitus when administered during the first 5 days following the acoustic trauma and also failed to reverse it when treatment was carried out every day for 4.5 weeks. We also found that treatment with L-baclofen did not alter the expression of the GABA(B)-R2 subunit in the cochlear nucleus of noise-exposed animals.
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Affiliation(s)
- Y Zheng
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - K McPherson
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - P F Smith
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
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Pace E, Zhang J. Noise-induced tinnitus using individualized gap detection analysis and its relationship with hyperacusis, anxiety, and spatial cognition. PLoS One 2013; 8:e75011. [PMID: 24069375 PMCID: PMC3771890 DOI: 10.1371/journal.pone.0075011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 08/10/2013] [Indexed: 01/12/2023] Open
Abstract
Tinnitus has a complex etiology that involves auditory and non-auditory factors and may be accompanied by hyperacusis, anxiety and cognitive changes. Thus far, investigations of the interrelationship between tinnitus and auditory and non-auditory impairment have yielded conflicting results. To further address this issue, we noise exposed rats and assessed them for tinnitus using a gap detection behavioral paradigm combined with statistically-driven analysis to diagnose tinnitus in individual rats. We also tested rats for hearing detection, responsivity, and loss using prepulse inhibition and auditory brainstem response, and for spatial cognition and anxiety using Morris water maze and elevated plus maze. We found that our tinnitus diagnosis method reliably separated noise-exposed rats into tinnitus(+) and tinnitus(−) groups and detected no evidence of tinnitus in tinnitus(−) and control rats. In addition, the tinnitus(+) group demonstrated enhanced startle amplitude, indicating hyperacusis-like behavior. Despite these results, neither tinnitus, hyperacusis nor hearing loss yielded any significant effects on spatial learning and memory or anxiety, though a majority of rats with the highest anxiety levels had tinnitus. These findings showed that we were able to develop a clinically relevant tinnitus(+) group and that our diagnosis method is sound. At the same time, like clinical studies, we found that tinnitus does not always result in cognitive-emotional dysfunction, although tinnitus may predispose subjects to certain impairment like anxiety. Other behavioral assessments may be needed to further define the relationship between tinnitus and anxiety, cognitive deficits, and other impairments.
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Affiliation(s)
- Edward Pace
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Communication Sciences & Disorders, Wayne State University College of Liberal Arts & Sciences, Detroit, Michigan, United States of America
- * E-mail:
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Zheng Y, McNamara E, Stiles L, Darlington CL, Smith PF. Evidence that Memantine Reduces Chronic Tinnitus Caused by Acoustic Trauma in Rats. Front Neurol 2012; 3:127. [PMID: 23015804 PMCID: PMC3449490 DOI: 10.3389/fneur.2012.00127] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/25/2012] [Indexed: 01/24/2023] Open
Abstract
Subjective tinnitus is a chronic neurological disorder in which phantom sounds are perceived. Increasing evidence suggests that tinnitus is caused by neuronal hyperactivity in auditory brain regions, either due to a decrease in synaptic inhibition or an increase in synaptic excitation. One drug investigated for the treatment of tinnitus has been the uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, memantine, although the evidence relating to it has been unconvincing to date. We re-investigated the effects of memantine on the behavioral manifestations of tinnitus induced by acoustic trauma (a 16-kHz, 110-dB pure tone presented unilaterally for 1 h) in rats. We used a conditioned lick suppression model in which lick suppression was associated with the perception of high frequency sound resembling tinnitus and a suppression ratio (SR) was calculated by comparing the number of licks in the 15-s period preceding the stimulus presentation (A) and the 15-s period during the stimulus presentation (B), i.e., SR = B/(A + B). Acoustic trauma resulted in a significant increase in the auditory brainstem-evoked response (ABR) threshold in the affected ear (P ≤ 0.0001) and a decrease in the SR compared to sham controls in response to 32 kHz tones in five out of eight acoustic trauma-exposed animals. A 5-mg/kg dose of memantine significantly reduced the proportion of these animals which exhibited tinnitus-like behavior (2/5 compared to 5/5; P ≤ 0.006), suggesting that the drug reduced tinnitus. These results suggest that memantine may reduce tinnitus caused by acoustic trauma.
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Affiliation(s)
- Yiwen Zheng
- Department of Pharmacology and Toxicology, Brain Health Research Centre, School of Medical Sciences, University of Otago Dunedin, New Zealand
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Yu–guang N, Doolittle L, Rong–guang W, Wei S. Tinnitus and hyperacusis in children: clinic reports and basic research. J Otol 2012. [DOI: 10.1016/s1672-2930(12)50004-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Zheng Y, Vagal S, McNamara E, Darlington CL, Smith PF. A dose-response analysis of the effects of L-baclofen on chronic tinnitus caused by acoustic trauma in rats. Neuropharmacology 2011; 62:940-6. [PMID: 22005094 DOI: 10.1016/j.neuropharm.2011.09.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/20/2011] [Accepted: 09/22/2011] [Indexed: 11/19/2022]
Abstract
Subjective tinnitus is a chronic neurological disorder in which phantom sounds are perceived. Drugs that increase GABAergic neurotransmission in the CNS are sometimes used as a treatment. One such drug is the GABA(B) receptor agonist L-baclofen. The aim of this study was to investigate the effects of L-baclofen on the psychophysical attributes of tinnitus in rats.The effects of 1, 3 or 5 mg/kg L-baclofen (s.c.) on the psychophysical attributes of tinnitus were investigated using a conditioned lick suppression model, following acoustic trauma (a 16 kHz, 110 dB pure tone presented unilaterally for 1 h) in rats. In pre-drug testing, acoustic trauma resulted in a significant increase in the auditory brainstem-evoked response (ABR) threshold in the affected ear (P < 0.008) and a significant decrease in the suppression ratio (SR) compared to sham controls in response to the 20 kHz tones, but not the broadband noise or the 10 kHz tones (P < 0.002). The 3 and 5 mg/kg doses of L-baclofen significantly reversed the frequency-specific decrease in the SR in the acoustic trauma group, indicating that the drug reduced tinnitus. Following washout from the 3 mg/kg dose, but not the 5 mg/kg dose, the significant decrease in the SR for the acoustic trauma group returned, suggesting a return of the tinnitus. These results suggest that L-baclofen should be reconsidered as a drug treatment for tinnitus. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, P.O. Box 913, Dunedin, New Zealand
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