Gustatory coding in brainstem nuclei using a novel c-Fos-tau-LacZ mouse model

描述（由申请人提供）：肥胖是一个主要的健康问题，大约三分之二的美国人口被认为超重，三分之一的人被归类为肥胖。过度食用高热量食物对肥胖的发展有很大的影响。因此，识别影响食物选择的因素对于开发有效的肥胖治疗方法非常重要。在这方面，味觉对食物偏好有直接影响。因此，参与大脑如何代表味觉的神经通路有助于我们理解肥胖的病因。最有效和广泛使用的方法来确定的神经基板，味觉的基础是可视化的空间模式的表达的活动依赖性标记，c-Fos的。 最近，开发了Fos-tau-LacZ转基因小鼠系，其中c-Fos基因的活化导致tau连接的2-半乳糖苷酶（2-gal）在活化细胞的细胞质中表达;从而能够检查c-Fos阳性细胞的形态。此外，2-gal在这些转基因小鼠中的持续时间比c-Fos蛋白本身长得多;刺激后24小时可以在脑干中观察到2-gal，而c-Fos蛋白持续1-3小时，c-Fos mRNA在刺激后30分钟达到峰值。2-gal和mRNA持续时间之间的这种时间差异使得能够在同一动物内观察响应于时间上分开的两种刺激的c-Fos表达（例如2-gal表达和c-Fos mRNA表达）。因此，我可以评估单个细胞是否对多种味觉刺激做出反应。 目前的建议将使用Fos-tau-LacZ转基因小鼠来量化脑干味觉核中细胞活化（例如2-gal表达和c-Fos mRNA）的形态和空间差异，以响应不同形式（甜、“鲜味”/咸和苦）和不同味觉快感（食欲与厌恶）的刺激。此外，该提案还将评估通过删除T1 R3受体（检测这些品质的强制性亚基）而丧失甜味和鲜味特异性感觉输入后这种中枢味觉表征的变化。从这个建议获得的数据将提供有价值的洞察力的空间和形态组织内的孤束核的味觉表征。 公共卫生相关性：味觉在营养选择和肥胖的发展中起着重要作用。了解味觉如何在大脑中表现以及这种表现在感觉丧失后如何变化，对于开发有效的肥胖治疗方法以帮助患者减少食物摄入至关重要。拟议的研究将确定味觉如何在大脑中表现，以及味觉的丧失如何导致大脑的重组。

DESCRIPTION (provided by applicant): Obesity is a major health issue with approximately two thirds of the U.S. population considered overweight and a third of those classified as obese. Overconsumption of high calorie foods contributes significantly to the development of obesity. Thus, identification of factors that influence food choice is important for the development of effective obesity treatments. In this regard, the sense of taste has a direct impact on food preference. Therefore, the neural pathways involved in how the brain represents taste can contribute to our understanding of the etiology of obesity. One of the most effective and widely-used methods to determine the neural substrate that underlies sensation of taste is visualization of the spatial patterns of expression of the activity-dependent marker, c-Fos. Recently, the Fos-tau-LacZ transgenic mouse line was developed in which activation of the c-Fos gene results in expression of tau-linked 2-galactosidase (2-gal) in the cytoplasm of activated cells; thereby enabling the examination of the morphology of c-Fos positive cells. Furthermore, the perdurance of 2-gal in these transgenic mice is much longer than c-Fos protein itself; 2-gal can be seen up to 24 hours post stimulation in the brainstem, whereas c-Fos protein lasts 1-3 hours and c-Fos mRNA peaks 30 min. post stimulation. This difference in timing between 2-gal and mRNA purdurance enables visualization of c-Fos expression in response to two stimuli, separated temporally, within the same animal (e.g. 2-gal) expression and c-Fos mRNA expression). Accordingly, I can assess whether individual cells respond to multiple taste stimuli. The current proposal will use Fos-tau-LacZ transgenic mice to quantify morphological and spatial differences in cellular activation (e.g. 2-gal expression and c-Fos mRNA) in brainstem taste nuclei in response to stimuli of different modalities (sweet, 'umami'/savory and bitter) and different taste hedonics (appetitive vs. aversive). Moreover, the proposal will also assess changes in this central taste representation following loss of sweet- and umami- specific sensory input via deletion of the T1R3 receptor, an obligatory subunit for the detection of these qualities. The data obtained from this proposal will provide valuable insight into the spatial and morphological organization of taste representation within the nucleus of the solitary tract. PUBLIC HEALTH RELEVANCE: The sense of taste plays an important role in nutrient selection and the development of obesity. Understanding how the sense of taste is represented in the brain and how this representation changes following sensory loss is essential in developing effective obesity treatments to help patients decrease their food intake. The proposed studies will determine how taste sensation is represented in the brain and how loss of taste sensation leads to reorganization in the brain.