Institute for Biology 2, RWTH Aachen University, Aachen, D-52074, Germany.
Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Kresge Hearing Research Institute, Ann Arbor, Michigan, 48109.
J Comp Neurol. 2018 Jul 1;526(10):1647-1661. doi: 10.1002/cne.24433. Epub 2018 Apr 1.
Principal neurons in the ventral cochlear nucleus (VCN) receive powerful ascending excitation and pass on the auditory information with exquisite temporal fidelity. Despite being dominated by ascending inputs, the VCN also receives descending cholinergic connections from olivocochlear neurons and from higher regions in the pontomesencephalic tegmentum. In Mongolian gerbils, acetylcholine acts as an excitatory and modulatory neurotransmitter on VCN neurons, but the anatomical structure of cholinergic innervation of gerbil VCN is not well described. We applied fluorescent immunohistochemical staining to elucidate the development and the cellular localization of presynaptic and postsynaptic components of the cholinergic system in the VCN of the Mongolian gerbil. We found that cholinergic fibers (stained with antibodies against the vesicular acetylcholine transporter) were present before hearing onset at P5, but innervation density increased in animals after P10. Early in development cholinergic fibers invaded the VCN from the medial side, spread along the perimeter and finally innervated all parts of the nucleus only after the onset of hearing. Cholinergic fibers ran in a rostro-caudal direction within the nucleus and formed en-passant swellings in the neuropil between principal neurons. Nicotinic and muscarinic receptors were expressed differentially in the VCN, with nicotinic receptors being mostly expressed in dendritic areas while muscarinic receptors were located predominantly in somatic membranes. These anatomical data support physiological indications that cholinergic innervation plays a role in modulating information processing in the cochlear nucleus.
腹侧耳蜗核（VCN）中的主要神经元接收强大的上行兴奋，并以极高的时间精度传递听觉信息。尽管主要由上行输入支配，但 VCN 还接收来自橄榄耳蜗神经元和桥脑被盖中部更高区域的下行胆碱能连接。在蒙古沙鼠中，乙酰胆碱作为 VCN 神经元的兴奋性和调制性神经递质发挥作用，但沙鼠 VCN 的胆碱能支配的解剖结构尚未得到很好的描述。我们应用荧光免疫组织化学染色来阐明蒙古沙鼠 VCN 中胆碱能系统的突触前和突触后成分的发育和细胞定位。我们发现，在 P5 之前，即听力出现之前，就存在对囊泡乙酰胆碱转运体有反应的胆碱能纤维（用针对该蛋白的抗体染色），但在 P10 之后，支配密度增加。在发育早期，胆碱能纤维从内侧侵入 VCN，沿着周边扩散，仅在听力出现后才支配核的所有部分。胆碱能纤维在核内呈前后向运行，并在主要神经元之间的神经间质中形成经过性肿胀。VCN 中表达了不同的烟碱型和毒蕈碱型受体，烟碱型受体主要在树突区表达，而毒蕈碱型受体主要位于体细胞膜上。这些解剖学数据支持生理指标表明，胆碱能支配在调节耳蜗核中的信息处理中发挥作用。
