Parvane Mahdi, A. Pourbakht, V. Mahabadi, A. Yazdi, M. Anari, M. Kamali
{"title":"Cochlear Synaptopathy Following Noise Exposure in Guinea Pigs:\nIts Electrophysiological and Histological Assessments","authors":"Parvane Mahdi, A. Pourbakht, V. Mahabadi, A. Yazdi, M. Anari, M. Kamali","doi":"10.32604/sv.2020.09880","DOIUrl":null,"url":null,"abstract":"Exposure to high level of noise, may cause the permanent cochlear synaptic degeneration. In present study, a model of noise induced cochlear synaptopathy was established and the electrophysiological and histological metrics for its assessment was designed. 6 guinea pigs were subjected to a synaptopathic noise (octave band of 4 kHz at 104 dB SPL, for 2-h). The amplitude growth curve of Auditory Brainstem Response (ABR) wave-I and wave-III latency shift in presence of noise were calculated. These indexes were considered in pre-exposure, 1 day post exposure (1DPE), 1 week post exposure (1WPE) and 1 month post exposure (1MPE) to noise. Finally, the samples were histologically analyzed. ABR wave-I amplitude was different between pre and 1DPE (p-value ≤ 0.05). However, at 1WPE, it was recovered at low intensities but at 70 dB SPL and above, the differences persisted even till 1MPE. In masked ABR, the latency shift of wave-III was different between pre and 3 post exposure assessments (p-value ≤ 0.05). Electro-microscopic analysis confirmed the synaptic degeneration, as the ribbons were larger than normal, hollow inside, and spherical and irregular in shape, also, the post synaptic density was abnormally thick and missed its flat orientation. These data revealed that noise at level below that can produce permanent hearing loss, can incur synaptic injury. So, noise is considered to be more damaging than previously thought. Accordingly, designing tools for clinical assessment of synaptopathy is beneficial in comprehensive auditory evaluation of those with history of noise exposure and also in hearing protection planning.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":"19 1","pages":""},"PeriodicalIF":0.9000,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Sound and Vibration","FirstCategoryId":"1089","ListUrlMain":"https://doi.org/10.32604/sv.2020.09880","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ACOUSTICS","Score":null,"Total":0}
引用次数: 0
Abstract
Exposure to high level of noise, may cause the permanent cochlear synaptic degeneration. In present study, a model of noise induced cochlear synaptopathy was established and the electrophysiological and histological metrics for its assessment was designed. 6 guinea pigs were subjected to a synaptopathic noise (octave band of 4 kHz at 104 dB SPL, for 2-h). The amplitude growth curve of Auditory Brainstem Response (ABR) wave-I and wave-III latency shift in presence of noise were calculated. These indexes were considered in pre-exposure, 1 day post exposure (1DPE), 1 week post exposure (1WPE) and 1 month post exposure (1MPE) to noise. Finally, the samples were histologically analyzed. ABR wave-I amplitude was different between pre and 1DPE (p-value ≤ 0.05). However, at 1WPE, it was recovered at low intensities but at 70 dB SPL and above, the differences persisted even till 1MPE. In masked ABR, the latency shift of wave-III was different between pre and 3 post exposure assessments (p-value ≤ 0.05). Electro-microscopic analysis confirmed the synaptic degeneration, as the ribbons were larger than normal, hollow inside, and spherical and irregular in shape, also, the post synaptic density was abnormally thick and missed its flat orientation. These data revealed that noise at level below that can produce permanent hearing loss, can incur synaptic injury. So, noise is considered to be more damaging than previously thought. Accordingly, designing tools for clinical assessment of synaptopathy is beneficial in comprehensive auditory evaluation of those with history of noise exposure and also in hearing protection planning.
暴露在高水平的噪音中,可能导致永久性的耳蜗突触变性。本研究建立了噪声性耳蜗突触病模型,并设计了评价噪声性耳蜗突触病的电生理和组织学指标。将6只豚鼠置于突触病变噪声(4 kHz, 104 dB SPL,倍频带)下2小时。计算噪声存在下听觉脑干反应(ABR)波i和波iii潜伏期移位的振幅增长曲线。这些指标分别在噪声暴露前、暴露后1天(1DPE)、暴露后1周(1WPE)和暴露后1个月(1MPE)进行考虑。最后,对样本进行组织学分析。ABR波i幅值与dpe前后存在差异(p值≤0.05)。然而,在1WPE时,它在低强度下恢复,但在70 dB SPL及以上,差异甚至持续到1MPE。在隐蔽性ABR中,暴露前和暴露后3次评估中,iii波的潜伏期移位有差异(p值≤0.05)。电镜分析证实突触变性,突触带比正常大,内部空心,形状呈球形不规则,突触后密度异常增厚,失去了其平面取向。这些数据表明,低于这个水平的噪音会导致永久性听力丧失,会导致突触损伤。因此,噪音被认为比之前认为的更具破坏性。因此,设计突触病的临床评估工具,有利于噪声暴露史患者的综合听觉评估和听力保护规划。
期刊介绍:
Sound & Vibration is a journal intended for individuals with broad-based interests in noise and vibration, dynamic measurements, structural analysis, computer-aided engineering, machinery reliability, and dynamic testing. The journal strives to publish referred papers reflecting the interests of research and practical engineering on any aspects of sound and vibration. Of particular interest are papers that report analytical, numerical and experimental methods of more relevance to practical applications.
Papers are sought that contribute to the following general topics:
-broad-based interests in noise and vibration-
dynamic measurements-
structural analysis-
computer-aided engineering-
machinery reliability-
dynamic testing