Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Exp Gerontol. 2012 Dec;47(12):966-73. doi: 10.1016/j.exger.2012.09.001. Epub 2012 Sep 12.
The behavioral consequences of age-related changes in the auditory system were studied in Fischer 344 (F344) rats as a model of fast aging and in Long Evans (LE) rats as a model of normal aging. Hearing thresholds, the strength of the acoustic startle responses (ASRs) to noise and tonal stimuli, and the efficiency of the prepulse inhibition (PPI) of ASR were assessed in young-adult, middle-aged, and aged rats of both strains. Compared with LE rats, F344 rats showed larger age-related hearing threshold shifts, and the amplitudes of their startle responses were mostly lower. Both rat strains demonstrated a significant decrease of startle reactivity during aging. For tonal stimuli, this decrease occurred at an earlier age in the F344 rats: middle-aged F344 animals expressed similar startle reactivity as aged F344 animals, whereas middle-aged LE animals had similar startle reactivity as young-adult LE animals. For noise stimuli, on the other hand, a similar progression of age-related ASR changes was found in both strains. No significant relationship between the hearing thresholds and the ASR amplitudes was found within any age group. Auditory PPI was less efficient in F344 rats than in LE rats. An age-related reduction of the PPI of ASR was observed in rats of both strains; however, a significant reduction of PPI occurred only in aged rats. The results indicate that the ASR may serve as an indicator of central presbycusis.
以快速老化模型 Fischer 344（F344）大鼠和正常老化模型 Long Evans（LE）大鼠为研究对象，研究了听觉系统与年龄相关变化的行为后果。评估了两个品系的青年、中年和老年大鼠的听力阈值、对噪声和音调刺激的声发射反应（ASR）强度以及 ASR 的前脉冲抑制（PPI）效率。与 LE 大鼠相比，F344 大鼠表现出更大的与年龄相关的听力阈值变化，其 ASR 幅度大多较低。两种大鼠品系在衰老过程中均表现出明显的 ASR 反应性下降。对于音调刺激，F344 大鼠的这种下降发生在更早的年龄：中年 F344 动物的 ASR 反应与老年 F344 动物相似，而中年 LE 动物的 ASR 反应与青年 LE 动物相似。对于噪声刺激，另一方面，两种品系的 ASR 随年龄变化的进展相似。在任何年龄组内，听力阈值与 ASR 幅度之间均未发现显著相关性。F344 大鼠的听觉 PPI 效率低于 LE 大鼠。在两种大鼠品系中均观察到 ASR 的 PPI 随年龄的降低；然而，仅在老年大鼠中才观察到 PPI 的显著降低。结果表明，ASR 可作为中枢性 presbycusis 的指标。
