Department of Morphological Neuroscience, Division of Neuroscience, Gifu University Graduate School of Medicine, Yanagido 1-1, Gifu 501-1194, Japan.
Neurosci Res. 2010 Oct;68(2):103-6. doi: 10.1016/j.neures.2010.06.012. Epub 2010 Jul 3.
The ganglion-cells in the mesencephalic trigeminal nucleus (Me5) process proprioceptive signals from the masticatory muscles and the periodontal ligaments, and are considered to regulate the rhythm of biting and bite strength. The locus coeruleus (LC) is the major source of noradrenergic projections in the brain and plays an important role in stressful situations and aggressive behavior. The two nuclei are adjacently located to each other in the lateral part of the periaqueductal gray matter of the fourth ventricle. In the present study, a small number of neurons were labeled in the LC with a neuronal tracer biotinylated dextran amine. The labeled single axons were traced from the labeled LC neuronal somata to the ipsilateral Me5 region where they produced terminal-like swellings. Some of the swellings appeared to make contact with the ganglion-cells of the Me5. These results suggest that the LC regulates the bite strength by modifying the ganglion-cell activity in the Me5. Additionally, these findings shed light on the enigma of why the main part of the Me5 at the level of pons is located at the lateral end of the gray matter ventral to the fourth ventricle, instead of at the trigeminal ganglion.
中脑三叉神经核（Me5）中的神经节细胞处理来自咀嚼肌和牙周韧带的本体感觉信号，被认为可以调节咀嚼的节奏和咬合力。蓝斑核（LC）是脑中去甲肾上腺素能投射的主要来源，在应激状态和攻击性行为中发挥重要作用。这两个核在第四脑室外侧的导水管周围灰质的相邻部位彼此相邻。在本研究中，使用神经元示踪剂生物素化葡聚糖胺对 LC 中的少数神经元进行了标记。标记的单轴突从标记的 LC 神经元胞体追踪到同侧 Me5 区，在那里它们产生末端样膨体。一些膨体似乎与 Me5 的神经节细胞接触。这些结果表明，LC 通过改变 Me5 中的神经节细胞活动来调节咬合力。此外，这些发现揭示了为什么 Me5 的主要部分在桥脑水平位于第四脑室腹侧灰质的外侧末端，而不是在三叉神经节的谜底。
