Department of Neurobiology, Harvard Medical School, Boston, United States.
Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, Bethesda, United States.
Elife. 2023 Mar 6;12:e83855. doi: 10.7554/eLife.83855.
Brainstem olivocochlear neurons (OCNs) modulate the earliest stages of auditory processing through feedback projections to the cochlea and have been shown to influence hearing and protect the ear from sound-induced damage. Here, we used single-nucleus sequencing, anatomical reconstructions, and electrophysiology to characterize murine OCNs during postnatal development, in mature animals, and after sound exposure. We identified markers for known medial (MOC) and lateral (LOC) OCN subtypes, and show that they express distinct cohorts of physiologically relevant genes that change over development. In addition, we discovered a neuropeptide-enriched LOC subtype that produces Neuropeptide Y along with other neurotransmitters. Throughout the cochlea, both LOC subtypes extend arborizations over wide frequency domains. Moreover, LOC neuropeptide expression is strongly upregulated days after acoustic trauma, potentially providing a sustained protective signal to the cochlea. OCNs are therefore poised to have diffuse, dynamic effects on early auditory processing over timescales ranging from milliseconds to days.
脑桥橄榄耳蜗神经元（OCN）通过向耳蜗的反馈投射来调节听觉处理的最早阶段，并且已被证明可以影响听力并保护耳朵免受声音引起的损伤。在这里，我们使用单核 RNA 测序、解剖重建和电生理学技术，在出生后发育、成熟动物和声音暴露后，对小鼠 OCN 进行了特征描述。我们鉴定了已知的内侧（MOC）和外侧（LOC）OCN 亚型的标记物，并表明它们表达了在发育过程中发生变化的不同生理相关基因群。此外，我们发现了一种富含神经肽的 LOC 亚型，它除了其他神经递质外，还产生神经肽 Y。在整个耳蜗中，两种 LOC 亚型的树突都在广泛的频率范围内延伸。此外，LOC 神经肽表达在声创伤后数天内强烈上调，可能为耳蜗提供持续的保护信号。因此，OCN 有可能在从毫秒到数天的时间范围内对早期听觉处理产生弥散的、动态的影响。
