Morphology & Physiology of Solitary Chemoreceptor Cells

描述(申请人提供)：小鼠和大鼠的鼻三叉神经化疗敏感性部分是由鼻上皮中的孤立化学感受器细胞(SCCs)介导的。SCCs除了表达包括PLCp2、Trpm5和T2R在内的“苦味”信号级联的其他元件外，还表达G蛋白a-gustducin。许多有毒物质在口腔中会引起苦味的感觉，但在鼻腔中会刺激或疼痛。拟议的实验分为两个目的：第一，描述支配SCCs的三叉神经伤害感受性纤维的类型。我们将利用免疫细胞化学来检测支配SCCs的神经纤维的神经肽含量、与异凝素B4结合的能力以及P2X3和海人藻酸受体的表达，这两种受体通常由伤害性纤维表达。其次，我们将调查SCC反应的哪一部分是由Trpm5介导的。TrpMS是T2R介导的味觉细胞反应的必需成分，而Trpm5-KO小鼠缺乏对T2R配体的味觉反应。我们将使用钙成像来可视化SCC对来自一组经典苦味和三叉神经刺激的测试刺激的反应。野生型和Trpm5-KO小鼠的干细胞将记录反应，以区分Trpm5和非Trpm5介导的反应。

DESCRIPTION (provided by applicant): Nasal trigeminal chemosensitivity in mice and rats is mediated in part by solitary chemoreceptor cells (SCCs) in the nasal epithelium. SCCs express the G-protein a-gustducin in addition to other elements of the "bitter"- taste signaling cascade including PLCp2, TrpM5 and T2R "bitter"-taste receptors. Many noxious substances elicit the sensation of bitter taste in the oral cavity but are irritating or painful in the nasal cavity. The proposed experiments fall into 2 aims: first to describe what type of trigeminal nociceptive fibers innervate SCCs. We will utilize immunocytochemistry to assay nerve fibers innervating SCCs for neuropeptide content, the ability to bind isolectin B4, and the expression of P2X3 and kainate receptors, both of which are commonly expressed by nociceptive fibers. Second, we will investigate which part of the SCC response is TrpM5-mediated. TrpMS is an obligatory component of T2R-mediated responses in taste cells and TrpM5- KO mice lack taste responses to T2R ligands. We will use calcium imaging to visualize SCC responses to test stimuli from a panel of classic bitter and trigeminal stimuli. Responses will be recorded in SCCs from both wild type and TrpM5-KO mice to separate TrpM5 and non-TrpM5-mediated responses.