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

描述(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被认为超重，三分之一的人被归类为肥胖者。过度食用高热量食物极大地促进了肥胖的发展。因此，确定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，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。确定味觉背后的神经底物的最有效和最广泛使用的方法之一是可视化活动依赖标记物c-Fos的空间表达模式。最近，Fos-tau-lacZ转基因小鼠品系被建立，其中c-Fos基因的激活导致激活细胞胞浆中tau连接的2-半乳糖苷酶(2-Gal)的表达，从而使c-Fos阳性细胞的形态观察成为可能。此外，在这些转基因小鼠中，2-半乳糖的耐受性比c-Fos蛋白本身要长得多，刺激后24小时脑干中可见2-半乳糖的存在，而c-Fos蛋白持续1-3小时，c-Fos信使核糖核酸在30分钟内达到高峰。刺激后。2-半乳糖和信使核糖核酸持续时间上的这种差异使得c-Fos的表达能够对同一动物中时间上分离的两个刺激做出反应(例如，2-半乳糖的表达和c-Fos的信使核糖核酸的表达)。因此，我可以评估单个细胞是否对多种味觉刺激做出反应。目前的提议将使用Fos-tau-LacZ转基因小鼠来量化脑干味觉核团细胞激活的形态和空间差异(例如，2-Gal表达和c-Fos mRNA)，以响应不同形式(甜味、鲜味/可口和苦味)和不同味觉享乐者(胃口与厌恶)的刺激。此外，该提案还将评估甜味和鲜味特有的感觉输入由于T1R3受体的缺失而失去后中央味觉表征的变化，T1R3受体是检测这些品质的必需亚单位。本研究获得的数据将对孤束核内味觉表征的空间和形态组织提供有价值的见解。 公共卫生相关性：味觉在营养选择和肥胖症的发展中起着重要作用。了解味觉在大脑中是如何表现的，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量是至关重要的。这项拟议的研究将确定味觉如何在大脑中表现出来，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.