Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois.
Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
J Comp Neurol. 2019 Oct 1;527(14):2302-2316. doi: 10.1002/cne.24682. Epub 2019 Mar 25.
Compared to many other rodent species, naked mole rats (Heterocephalus glaber) have elevated auditory thresholds, poor frequency selectivity, and limited ability to localize sound. Because the cochlea is responsible for encoding and relaying auditory signals to the brain, we used immunofluorescence and quantitative image analysis to examine cochlear innervation in mature and developing naked mole rats compared to mice (Mus musculus), gerbils (Meriones unguiculatus), and Damaraland mole rats (Fukomys damarensis), another subterranean rodent. In comparison to mice and gerbils, we observed alterations in afferent and efferent innervation as well as their patterns of developmental refinement in naked and Damaraland mole rats. These alterations were, however, not always shared similarly between naked and Damaraland mole rats. Most conspicuously, in both naked and Damaraland mole rats, inner hair cell (IHC) afferent ribbon density was reduced, whereas outer hair cell afferent ribbon density was increased. Naked and Damaraland mole rats also showed reduced lateral and medial efferent terminal density. Developmentally, naked mole rats showed reduced and prolonged postnatal reorganization of afferent and efferent innervation. Damaraland mole rats showed no evidence of postnatal reorganization. Differences in cochlear innervation specifically between the two subterranean rodents and more broadly among rodents provides insight into the cochlear mechanisms that enhance frequency sensitivity and sound localization, maturation of the auditory system, and the evolutionary adaptations occurring in response to subterranean environments.
与许多其他啮齿动物物种相比，裸鼹鼠（Heterocephalus glaber）的听觉阈值较高，频率选择性差，定位声音的能力有限。由于耳蜗负责编码和将听觉信号传递到大脑，我们使用免疫荧光和定量图像分析来检查成熟和发育中的裸鼹鼠与小鼠（Mus musculus）、沙鼠（Meriones unguiculatus）和达马拉兰鼹鼠（Fukomys damarensis）的耳蜗神经支配，达马拉兰鼹鼠是另一种地下啮齿动物。与小鼠和沙鼠相比，我们观察到在裸鼹鼠和达马拉兰鼹鼠中，传入和传出神经支配及其发育精细模式发生了改变。然而，这些变化并不总是在裸鼹鼠和达马拉兰鼹鼠之间相似地共享。最明显的是，在裸鼹鼠和达马拉兰鼹鼠中，内毛细胞（IHC）传入纤维带密度降低，而外毛细胞传入纤维带密度增加。裸鼹鼠和达马拉兰鼹鼠的外侧和内侧传出终端密度也降低。在发育过程中，裸鼹鼠的传入和传出神经支配的后期组织减少且延长。达马拉兰鼹鼠没有表现出出生后的神经支配重组。两种地下啮齿动物之间以及更广泛的啮齿动物之间的耳蜗神经支配差异提供了有关增强频率敏感性和声音定位、听觉系统成熟以及对地下环境发生的进化适应的耳蜗机制的见解。
