Institute of Anatomy and Cell Biology, Ludwig-Maximilians-Universität, Munich, Germany.
German Center for Vertigo and Balance Disorders, Klinikum Grosshadern, Ludwig-Maximilians Universität, Munich, Germany.
Invest Ophthalmol Vis Sci. 2018 Jun 1;59(7):2944-2954. doi: 10.1167/iovs.18-24322.
To further chemically characterize palisade endings in extraocular muscles in rhesus monkeys.
Extraocular muscles of three rhesus monkeys were studied for expression of the calcium-binding protein calretinin (CR) in palisade endings and multiple endings. The complete innervation was visualized with antibodies against the synaptosomal-associated protein of 25 kDa and combined with immunofluorescence for CR. Six rhesus monkeys received tracer injections of choleratoxin subunit B or wheat germ agglutinin into either the belly or distal myotendinous junction of the medial or inferior rectus muscle to allow retrograde tracing in the C-group of the oculomotor nucleus. Double-immunofluorescence methods were used to study the CR content in retrogradely labeled neurons in the C-group.
A subgroup of palisade and multiple endings was found to express CR, only in the medial and inferior rectus muscle. In contrast, the en plaque endings lacked CR. Accordingly, within the tracer-labeled neurons of the C-group, a subgroup expressed CR.
The study indicates that two different neuron populations targeting nontwitch muscle fibers are present within the C-group for inferior rectus and medial rectus, respectively, one expressing CR, one lacking CR. It is possible that the CR-negative neurons represent the basic population for all extraocular muscles, whereas the CR-positive neurons giving rise to CR-positive palisade endings represent a specialized, perhaps more excitable type of nerve ending in the medial and inferior rectus muscles, being more active in vergence. The malfunction of this CR-positive population of neurons that target nontwitch muscle fibers could play a significant role in strabismus.
进一步对恒河猴眼外肌的栅栏状终末进行化学表征。
对 3 只恒河猴的眼外肌进行钙结合蛋白 calretinin（CR）在栅栏状终末和多终末中的表达研究。使用针对突触相关蛋白 25kDa 的抗体对完整的神经支配进行可视化，并与 CR 的免疫荧光结合。6 只恒河猴将霍乱毒素亚单位 B 或麦胚凝集素注射到内侧或下直肌的腹部或远肌肌腱连接处，以便在动眼神经核的 C 群中进行逆行示踪。使用双免疫荧光方法研究 C 群中逆行标记神经元中的 CR 含量。
发现一小部分栅栏状和多终末表达 CR，仅在内侧和下直肌中。相比之下，斑块状终末缺乏 CR。因此，在 C 群的示踪标记神经元中，有一小部分表达 CR。
该研究表明，C 群中分别针对下直肌和内直肌的非抽搐肌纤维存在两个不同的神经元群体，一个表达 CR，一个缺乏 CR。CR 阴性神经元可能代表所有眼外肌的基本群体，而产生 CR 阳性栅栏状终末的 CR 阳性神经元代表内直肌和下直肌中一种特殊的、可能更兴奋的神经末梢类型，在会聚中更活跃。靶向非抽搐肌纤维的 CR 阳性神经元群体的功能障碍可能在斜视中发挥重要作用。
