Morphology & Physiology of Solitary Chemoreceptor Cells

描述（由申请人提供）：小鼠和大鼠的鼻三叉神经化学敏感性部分由鼻上皮中的孤立化学受体细胞（SCCs）介导。SCCs除了表达“苦味”信号级联的其他元件外，还表达g蛋白a-gustducin，包括PLCp2， TrpM5和T2R“苦味”受体。许多有害物质在口腔中引起苦味的感觉，但在鼻腔中引起刺激或疼痛。提出的实验有两个目的：第一，描述什么类型的三叉神经伤害纤维支配SCCs。我们将利用免疫细胞化学检测支配SCCs的神经纤维的神经肽含量、结合分离素B4的能力以及P2X3和kainate受体的表达，这两种受体通常由伤害性纤维表达。其次，我们将研究SCC反应的哪一部分是trpm5介导的。TrpM5- KO小鼠缺乏对T2R配体的味觉反应。我们将使用钙显像来观察SCC对经典苦刺激和三叉神经刺激的反应。将在野生型和TrpM5- ko小鼠的SCCs中记录应答，以分离TrpM5和非TrpM5介导的应答。

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.