McFadden S L, Campo P, Ding D, Quaranta N
Center for Hearing and Deafness, Department of Communicative Disorders, University at Buffalo, NY 14214-3007, USA.
Hear Res. 1998 Mar;117(1-2):81-96. doi: 10.1016/s0378-5955(98)00013-6.
Like many aging humans, the aging chinchilla tends to lose high-frequency sensitivity at a faster rate than low-frequency sensitivity. This feature, combined with its excellent low-frequency hearing, makes the chinchilla attractive as an animal model for studying the relationship between noise-induced hearing loss (NIHL) and age-related hearing loss (AHL). In the present study, we examined susceptibility to noise in 15 aged (10-15 years old) and 15 young chinchillas. Two levels of noise were used, with the aim of determining whether age-related differences exist in the magnitude and rate of recovery from temporary threshold shifts produced by a moderate-level (95 dB) noise exposure, or in susceptibility to permanent threshold shifts and cochlear damage caused by a high-level (106 dB) noise exposure. Thresholds and response amplitudes at 0.5, 1, 2, 4, 8 and 16 kHz were determined from evoked potentials recorded from the inferior colliculus. Cochlear histology was performed on animals exposed to high-level noise. The results suggest that older animals are equally vulnerable to moderate-level noise, but may be slightly more vulnerable to high-level noise. For moderate-level exposures, there appears to be a simple additive relationship (in dB) between AHL and NIHL. For high-level exposures, the relationship may be more complex.
与许多衰老的人类一样，衰老的毛丝鼠高频敏感度的丧失速度往往比低频敏感度更快。这一特征，再加上其出色的低频听力，使得毛丝鼠成为研究噪声性听力损失（NIHL）与年龄相关性听力损失（AHL）之间关系的极具吸引力的动物模型。在本研究中，我们检测了15只老年（10 - 15岁）和15只幼年毛丝鼠对噪声的易感性。使用了两种噪声水平，目的是确定在中等强度（95分贝）噪声暴露产生的暂时阈移的恢复幅度和恢复速率方面，或者在高强度（106分贝）噪声暴露导致的永久性阈移和耳蜗损伤的易感性方面，是否存在与年龄相关的差异。从下丘记录的诱发电位确定了0.5、1、2、4、8和16千赫处的阈值和反应幅度。对暴露于高强度噪声的动物进行了耳蜗组织学检查。结果表明，老年动物对中等强度噪声同样易感，但可能对高强度噪声稍更易感。对于中等强度暴露，AHL和NIHL之间似乎存在简单的相加关系（以分贝计）。对于高强度暴露，这种关系可能更为复杂。
