Neuropeptide Modulation of Taste Signals

描述（由申请人提供）：许多作用于下丘脑核的神经活性肽是通过肠-（血）-脑轴调节食物摄入的至关重要的中枢调节剂。催产素是一种有效的厌氧肽，在调节食欲、饱腹感和摄入的下丘脑和后脑中枢起着关键作用。口味强烈地影响着食物的选择。然而，味觉的作用还没有被整合到食欲和饱腹感的模型中。这种应用的前提是催产素，除了它的中枢作用，也调节外围味觉信号。催产素敲除小鼠表现出味觉敏感度和偏好的改变，尤其是对甜味剂的偏好。我们的初步数据表明，催产素的膜受体（OxtR）在味蕾内的一个离散细胞亚群中表达，并对催产素的生理浓度做出反应。根据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，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标来验证这一假设：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PLC22-GFP、GAD-GFP和OxtR-YFP中进行这些分析。2: OxtR是否在味蕾中起作用，是否影响味觉诱发反应？我们将在OxtR-YFP报告小鼠的味觉细胞上扩展我们的初步Ca2+成像实验。使用激光扫描共聚焦Ca2+成像舌片制备，我们将唤起对味觉化合物的反应，并询问催产素是否调节甜味（或其他）味觉诱发反应。我们还将研究味觉诱发的传入递质ATP的分泌是否受到催产素的调节。这些实验将在OxtR-YFP和PLC22-GFP的味觉组织上进行。所有提出的实现这些目标的方法，虽然技术性很强，但都在我们的实验室例行执行，并在我们的出版物中。这保证了项目的可行性。我们打算利用这一探索性研究基金（R21）来启动一个可能具有重大转化影响的新研究领域。了解肽（尤其是那些与饱腹感中枢通路有关的肽）如何影响外周味觉信号，可能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多肽调节食物摄入，并得到了深入研究。它们的功能失调会导致暴饮暴食或厌食行为，和/或体重变化。具有讽刺意味的是，进食最直观的驱动因素——味觉，并没有作为食欲调节的贡献者被研究过。我们提出证据并建议进一步研究，味觉系统如何被至少两种控制大脑饱腹感的相同肽调节。这一认识将为解决饮食失调提供新的药理可能性。

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.