Effect of aging on ultrasonic vocalizations and laryngeal sensorimotor neurons in rats
Effect of aging on ultrasonic vocalizations and laryngeal sensorimotor neurons in rats
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DOI：
10.1007/s00221-012-3096-6
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发表时间：
2012-06-01
影响因子：
2
通讯作者：
Ciucci, Michelle R.
中科院分区：
文献类型：
--
作者：
Basken, Jaime N.;Connor, Nadine P.;Ciucci, Michelle R.
虽然发声质量下降在老龄化人口中普遍存在，但导致年龄相关性发音困难的潜在神经生物学机制尚不清楚，很难在人类中进行研究。发展动物模型似乎是研究这一问题的关键。使用已建立的衰老大鼠模型，我们评估了10，32个月大的Fischer 344/Brown挪威大鼠与10，9个月大(年轻)大鼠的50 kHz超声波发声是否有所不同。将逆行示踪剂--贝塔霍乱毒素注射到甲状旁肌，以确定疑核运动神经元的丢失是否与年龄有关。结果表明，老年大鼠发声的声学复杂性降低，表现为带宽、强度和峰值频率降低，这些变化取决于50 kHz发声的类型。老年大鼠的简单叫声降低了带宽、峰值频率和强度，而老年大鼠的调频叫声降低了带宽和强度。令人惊讶的是，在老年大鼠中，一种叫声类型--步骤叫声--的持续时间延长了。这些发现反映了在老年人身上观察到的发音变化。我们还在老年大鼠的疑核中发现了显著的运动神经元丢失，这表明运动神经元的丢失可能是导致超声发声的复杂性和质量降低的一个因素。这些发现表明，大鼠超声发声模型可能有助于研究在人类中观察到的与年龄相关的发声变化。
While decline in vocal quality is prevalent in an aging population, the underlying neurobiological mechanisms contributing to age-related dysphonia are unknown and difficult to study in humans. Development of an animal model appears critical for investigating this issue. Using an established aging rat model, we evaluated if 50-kHz ultrasonic vocalizations in 10, 32-month-old (old) Fischer 344/Brown Norway rats differed from those in 10, 9-month-old (young adult) rats. The retrograde tracer, Cholera Toxin beta, was injected to the thyroarytenoid muscle to determine if motoneuron loss in the nucleus ambiguus was associated with age. Results indicated that older rats had vocalizations with diminished acoustic complexity as demonstrated by reduced bandwidth, intensity, and peak frequency, and these changes were dependent on the type of 50-kHz vocalization. Simple calls of old rats had reduced bandwidth, peak frequency, and intensity while frequency-modulated calls of old rats had reduced bandwidth and intensity. Surprisingly, one call type, step calls, had increased duration in the aged rats. These findings reflect phonatory changes observed in older humans. We also found significant motoneuron loss in the nucleus ambiguus of aged rats, which suggests that motoneuron loss may be a contributing factor to decreased complexity and quality of ultrasonic vocalizations. These findings suggest that a rat ultrasonic phonation model may be useful for studying age-related changes in vocalization observed in humans.