Uran S L, Gómez-Casati M E, Guelman L R
1(a) Cátedra de Farmacología, Facultad de Medicina, UBA, CEFYBO-CONICET, Buenos Aires, Argentina.
Instituto de Investigaciones en Ingeniería Genética y Biologia Molecular INGEBI-CONICET, Buenos Aires, Argentina; 3(a) Cátedra de Farmacología, Facultad de Medicina, UBA, Buenos Aires, Argentina.
Int J Dev Neurosci. 2014 Oct;37:41-51. doi: 10.1016/j.ijdevneu.2014.06.002. Epub 2014 Jun 6.
Sound is an important part of man's contact with the environment and has served as critical means for survival throughout his evolution. As a result of exposure to noise, physiological functions such as those involving structures of the auditory and non-auditory systems might be damaged. We have previously reported that noise-exposed developing rats elicited hippocampal-related histological, biochemical and behavioral changes. However, no data about the time lapse of these changes were reported. Moreover, measurements of auditory pathway function were not performed in exposed animals. Therefore, with the present work, we aim to test the onset and the persistence of the different extra-auditory abnormalities observed in noise-exposed rats and to evaluate auditory pathway integrity. Male Wistar rats of 15 days were exposed to moderate noise levels (95-97 dB SPL, 2 h a day) during one day (acute noise exposure, ANE) or during 15 days (sub-acute noise exposure, SANE). Hippocampal biochemical determinations as well as short (ST) and long term (LT) behavioral assessments were performed. In addition, histological and functional evaluations of the auditory pathway were carried out in exposed animals. Our results show that hippocampal-related behavioral and biochemical changes (impairments in habituation, recognition and associative memories as well as distortion of anxiety-related behavior, decreases in reactive oxygen species (ROS) levels and increases in antioxidant enzymes activities) induced by noise exposure were almost completely restored by PND 90. In addition, auditory evaluation shows that increased cochlear thresholds observed in exposed rats were re-established at PND 90, although with a remarkable supra-threshold amplitude reduction. These data suggest that noise-induced hippocampal and auditory-related alterations are mostly transient and that the effects of noise on the hippocampus might be, at least in part, mediated by the damage on the auditory pathway. However, we cannot exclude that a different mechanism might be responsible for the observed hippocampal-related changes.
声音是人类与环境接触的重要组成部分，在其整个进化过程中一直是生存的关键手段。由于接触噪音，涉及听觉和非听觉系统结构的生理功能可能会受到损害。我们之前曾报道，暴露于噪音中的发育中大鼠会引发与海马体相关的组织学、生化和行为变化。然而，当时并未报告这些变化的时间间隔数据。此外，也未对暴露动物的听觉通路功能进行测量。因此，在本研究中，我们旨在测试在暴露于噪音的大鼠中观察到的不同听觉外异常的起始和持续情况，并评估听觉通路的完整性。15日龄的雄性Wistar大鼠在一天内（急性噪音暴露，ANE）或15天内（亚急性噪音暴露，SANE）暴露于中等噪音水平（95 - 97 dB SPL，每天2小时）。进行了海马体生化测定以及短期（ST）和长期（LT）行为评估。此外，还对暴露动物的听觉通路进行了组织学和功能评估。我们的结果表明，噪音暴露引起的与海马体相关的行为和生化变化（习惯化、识别和联想记忆受损以及焦虑相关行为扭曲、活性氧（ROS）水平降低和抗氧化酶活性增加）在出生后第90天几乎完全恢复。此外，听觉评估表明，暴露大鼠中观察到的耳蜗阈值升高在出生后第90天恢复正常，尽管超阈值幅度显著降低。这些数据表明，噪音诱导的海马体和听觉相关改变大多是短暂的，并且噪音对海马体的影响可能至少部分是由听觉通路损伤介导的。然而，我们不能排除不同的机制可能导致观察到的与海马体相关的变化。
