RUI: Monosodium Glutamate and Amino Acid Tastes

RUI：谷氨酸钠和氨基酸味道

• 批准号: 0549167
• 负责人: Eugene Delay
• 金额: $ 39.49万
• 依托单位: University of Vermont & State Agricultural College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-28 至 2009-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0549167&HistoricalAwards=false
• 关键词: RUI; Monosodium; Glutamate; Amino; Acid

How food tastes greatly influences eating behavior. The tastes of monosodium glutamate (MSG), other amino acids, and sweet stimuli signal general food types and influence dietary intake. MSG, an amino acid that occurs naturally in foods such as vegetables and meats, elicits a taste called "umami" that increases the palatability of food and, thus, food intake. Unlike other primary tastes, sweet, sour, salty, and bitter, the biological mechanisms for detecting umami are not well understood. Although MSG has a prototypical umami quality, it has multiple perceptual qualities, possibly by stimulation of several taste receptors. Behavioral studies have shown that MSG also elicits taste qualities similar to sweet stimuli when the sodium taste is minimized. MSG is detected in part by a glutamate receptor called "taste-mGluR4". In rats, behavioral studies show that MSG and L-AP4 (an mGluR4 agonist) have nearly identical tastes. Nerve fiber recordings reveal that some fibers respond synergistically to mixtures of L-AP4 and sweet stimuli but, curiously, only fibers that respond weakly to sucrose alone. These same fibers do not show synergy to mixtures of MSG and sweet stimuli, suggesting that L-AP4 evokes a sweet taste through mGluR4 receptors. Molecular studies report that another potential umami receptor, T1R1/T1R3, responds broadly to L-amino acids, including MSG, but not to sweet stimuli. Together, these data suggest that there are multiple taste receptors for MSG and at least some L-amino acids but critical behavioral data are lacking. Using rats, Dr. Delay will combine pharmacological antagonism of specific receptors with behavioral methods, such as conditioned taste aversion (in which rats attend to perceptual similarities) and discrimination (in which rats attend to differences), to address three important questions: 1) Are taste-mGluR4 receptors involved in the sweet taste of MSG? 2) Does L-AP4 have a sweet quality and do taste-mGluR4 receptors contribute to this quality? 3) Is the taste of glutamate similar to other L-amino acids? Knowledge gained from these studies will help identify the taste receptors responsible for the perception of glutamate and amino acids. The project will provide opportunities for undergraduate students to gain knowledge and experience about research and scientific processes, and prepare for careers in science. The results may also help improve dietary intake of people who have deficiencies as a result of not eat well, e.g., elderly, chemotherapy patients, etc.

食物的味道在很大程度上影响着饮食行为。味精(MSG)、其他氨基酸和甜味刺激的味道标志着一般食物类型，并影响饮食摄入量。味精是一种天然存在于蔬菜和肉类等食物中的氨基酸，它会产生一种名为“鲜味”的味道，从而增加食物的适口性，从而增加食物的摄入量。与其他主要口味不同，甜味、酸味、咸味和苦味，检测鲜味的生物学机制还没有被很好地理解。虽然味精具有典型的鲜味品质，但它具有多种感知品质，可能是通过刺激几个味觉感受器。行为学研究表明，当钠的味道降到最低时，味精也会产生类似于甜味刺激的味道。味精部分是通过一种叫做“味觉-mGluR4”的谷氨酸受体来检测的。在大鼠身上，行为学研究表明，味精和L-AP4(一种mGluR4激动剂)的味道几乎相同。神经纤维记录显示，一些纤维对L-ap4和甜味刺激的混合物有协同反应，但奇怪的是，只有对蔗糖单独反应弱的纤维。这些相同的纤维对味精和甜味刺激的混合物没有表现出协同作用，这表明L-AP4通过mGluR4受体唤起甜味。分子研究表明，另一个潜在的鲜味受体T1R1/T1R3对L的氨基酸(包括味精)有广泛的反应，但对甜味刺激不起作用。综上所述，这些数据表明味精和至少一些L氨基酸有多种味觉感受器，但关键的行为数据缺乏。在大鼠身上，Delay博士将把特定受体的药理拮抗与行为方法相结合，如条件味觉厌恶(大鼠注意知觉的相似之处)和辨别(大鼠注意差异)，以解决三个重要问题：1)味觉-mGluR4受体是否参与味精的甜味？2)L-AP4是否具有甜味，味觉-mGluR4受体是否参与这种品质？3)谷氨酸的味道与其他L-氨基酸相似吗？从这些研究中获得的知识将有助于识别负责感知谷氨酸和氨基酸的味觉受体。该项目将为本科生提供获得有关研究和科学过程的知识和经验的机会，并为从事科学工作做准备。这一结果还可能有助于改善因饮食不佳而导致营养不良的人的饮食摄入量，例如老年人、化疗患者等。