Division of Oral Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan.
Neurosci Lett. 2011 Jan 20;488(2):173-7. doi: 10.1016/j.neulet.2010.11.023. Epub 2010 Nov 13.
The acid-sensing ion channel 3 (ASIC3), a member of the epithelial sodium channel/degenerin (ENaC/DEG) superfamily, has been reported to participate in acid sensing, mechanosensation, and nociception. However, no information is available regarding the precise localization and function of this molecule in the periodontal ligament, which contains abundant sensory nerves originating from the trigeminal ganglion. The present study examined the expression of ASIC3 in the lingual periodontal ligament of mouse incisors by immunohistochemistry. Furthermore, the expression of ASIC3 in the trigeminal ganglion - which innervates the periodontal ligament - was investigated at protein (immunohistochemistry and quantitative analysis) and mRNA levels (RT-PCR technique and in situ hybridization histochemistry). Immunohistochemistry for ASIC3 was able to demonstrate dendritic profiles of the periodontal Ruffini endings in the mouse incisors. No thin fibers terminating as nociceptive free nerve endings exhibited ASIC3 immunoreactivity. Double immunofluorescent staining revealed ASIC3 immunoreaction in the axoplasm but not in the ordinary Schwann cells - including the associated terminal Schwann cells. Observation of the trigeminal ganglia showed variously sized neurons expressing ASIC3 immunoreaction; the most intense immunopositivity was found in the small and medium-sized neurons, as confirmed by in situ hybridization histochemistry using a specific cRNA probe. Quantitative analysis on trigeminal ganglion neurons showed that 38.0% of ASIC3 neurons could be categorized as medium-sized neurons which mediate mechanotransduction. These findings suggest that ASIC3 functions as a molecule for mechanosensation in the periodontal Ruffini endings.
酸敏感离子通道 3（ASIC3）是上皮钠通道/退行性（ENaC/DEG）超家族的成员，据报道，它参与酸感应、机械感觉和伤害感受。然而，关于这个分子在牙周韧带中的精确定位和功能，尚无信息。牙周韧带含有丰富的感觉神经，源自三叉神经节。本研究通过免疫组织化学检查了 ASIC3 在小鼠切牙舌侧牙周韧带中的表达。此外，还在三叉神经节（支配牙周韧带的神经节）中研究了 ASIC3 的蛋白（免疫组织化学和定量分析）和 mRNA 水平（RT-PCR 技术和原位杂交组织化学）的表达。ASIC3 的免疫组织化学能够显示出小鼠切牙牙周韧带的 Ruffini 末梢的树突状形态。没有表现出 ASIC3 免疫反应的终止为伤害性游离神经末梢的细纤维。双重免疫荧光染色显示 ASIC3 免疫反应位于轴突浆中，而不在普通施万细胞中，包括相关的终末施万细胞。观察三叉神经节显示表达 ASIC3 免疫反应的大小不一的神经元；原位杂交组织化学使用特异性 cRNA 探针证实，最强烈的免疫阳性位于小和中型神经元中。三叉神经节神经元的定量分析表明，38.0%的 ASIC3 神经元可归类为介导机械转导的中型神经元。这些发现表明 ASIC3 作为牙周韧带 Ruffini 末梢的机械感觉分子发挥作用。
