Neuropeptide Modulation of Taste Signals

描述（由申请人提供）：作用于下丘脑核团的许多神经活性肽是通过肠-（血）-脑轴的食物摄入的至关重要的中枢调节剂。催产素是一种有效的促催产素肽，在调节食欲、饱腹感和摄取的下丘脑和后脑中心起关键作用。口味强烈影响食物的选择。然而，味觉的作用还没有被整合到食欲和饱腹感的模型中。这个应用的前提是，催产素，除了它的中枢作用，也调制外周味觉信号。催产素敲除小鼠表现出味觉敏感性和偏好的改变，特别是对甜味剂。我们的初步数据表明，催产素（OxtR）的膜受体表达在味蕾内的细胞的离散子集，并响应生理浓度的催产素。基于已发表的报告和我们的初步数据，我们假设催产素作用于味蕾内的胶质样细胞，并其次改变味蕾的甜味选择敏感性和输出。我们将通过以下具体目的来验证这一假设：1：哪些味觉细胞表达催产素受体？使用单细胞基因表达谱和免疫细胞化学，我们将测试这一点，因为细胞类型对功能有影响。我们将在野生型和转基因小鼠、PLC 22-GFP、GAD-GFP和OxtR-YFP中进行这些分析。2：OxtR在味蕾中是否起作用，它是否影响味觉诱发反应？我们将扩展我们的初步Ca 2+成像实验的味细胞从OxtR-YFP报告小鼠。使用激光扫描共聚焦钙离子成像的舌片制备，我们将引起反应的味道化合物，并询问催产素是否调制甜（或其他）味觉诱发的反应。我们还将检查，如果味觉诱发的传入递质，ATP的分泌，调制暴露于催产素。这些实验将在来自OxtR-YFP和PLC 22-GFP的味觉组织上进行。所有为实现这些目标而提出的方法，尽管技术性很强，但都是在我们的实验室中进行的，并在我们的出版物中进行。这就保证了项目的可行性。我们打算利用这一探索性研究补助金（R21）启动一个新的调查领域，可能会产生重大的翻译影响。了解肽（特别是那些参与饱腹感中枢通路的肽）如何影响外周味觉信号，可能会为解决饮食失调提供新的途径。 公共卫生相关性：大脑和肠道中的几种肽调节食物摄入，并进行了深入研究。它们的功能障碍导致暴饮暴食或肥胖行为，和/或体重变化。具有讽刺意味的是，进食最直观的驱动力，味觉，还没有被研究为食欲调节的贡献者。我们提出的证据，并建议进一步研究，味觉系统可能是如何调制的至少两个相同的肽，控制饱腹感在大脑中。这种理解将提出新的药理学可能性，以解决饮食失调。

DESCRIPTION (provided by applicant): Many neuroactive peptides, acting at hypothalamic nuclei, are critically important central regulators of food intake via the gut-(blood)-brain axis. Oxytocin is a potent anorexigenic peptide that plays a key role at hypothalamic and hindbrain centers that regulate appetite, satiety and ingestion. Taste strongly influences food selection. Yet, the role of taste has not been integrated into models of appetite and satiety. The premise of this application is that oxytocin, in addition to its central effects, also modulates the peripheral taste signal. Oxytocin knockout mice show altered taste sensitivity and preference, specifically for sweeteners. Our preliminary data show that a membrane receptor for Oxytocin (OxtR) is expressed in a discrete subset of cells within the taste bud, and responds to physiological concentrations of Oxytocin. Based on published reports and our preliminary data, we hypothesize that oxytocin acts on glial-like cells within taste buds, and secondarily alters the sweet-selective sensitivity and output of taste buds. We will test this hypothesis through the following Specific Aims: 1: Which taste cells express oxytocin receptor? Using single cell gene expression profiling and immunocytochemistry, we will test this because cell type has implications for function. We will conduct these analyses in wild-type and transgenic mice, PLC22-GFP, GAD-GFP and OxtR-YFP. 2: Is OxtR functional in taste buds and does it influence taste-evoked responses? We will extend our preliminary Ca2+ imaging experiments on taste cells from OxtR-YFP reporter mice. Using laser scanning confocal Ca2+ imaging on a lingual slice preparation, we will evoke responses to taste compounds, and ask whether oxytocin modulates sweet (or other) taste evoked responses. We will also examine if taste-evoked secretion of the afferent transmitter, ATP, is modulated by exposure to oxytocin. These experiments will be carried out on taste tissue from OxtR-YFP and PLC22-GFP. All proposed methodologies to achieve these aims, although highly technical, are routinely performed in our laboratories, and are in our publications. This assures the feasibility of the project. We intend to use this Exploratory Research grant (R21) to launch a new area of investigation that may have significant translational impact. Understanding how peptides (especially those implicated in central pathways for satiety) influence the peripheral taste signal may suggest new avenues to address eating disorders. PUBLIC HEALTH RELEVANCE: Several peptides in the brain and gut regulate food intake and are intensely researched. Their malfunction results in overeating or anorexic behaviors, and/or changes in body weight. Ironically, the most intuitive driver of feeding, taste, has not been investigated as a contributor to appetite regulation. We present evidence and propose to study further, how the taste system may be modulated by at least two of the same peptides that control satiety in the brain. This understanding would suggest new pharmacological possibilities to address eating disorders.