ROLE OF TRANSPORTERS IN RECOGNITION OF AMINO ACID STATUS

这项研究的长期目标是确定包括人类在内的杂食性动物识别大脑中不可或缺的氨基酸(IAA)稳态破坏的机制。其具体目的是：1)确定IAA转运蛋白是否能在体外激活神经元；2)通过大鼠的体内喂养研究，在体外分子水平和使用适当的转运蛋白抑制剂在功能水平上表征这些IAA转运蛋白。IAA营养和代谢紊乱是严重的人类健康问题，通常会导致衰弱的厌食症。这项工作对人类健康很重要，因为确定细胞对IAA营养中断的反应可以为医学干预提供建议。对饮食中IAA不成比例的摄食(厌食)反应已经被很好地研究了，但还不知道大脑如何在这一认识中起作用。我们假设神经细胞膜上的IAA离子交换改变了膜电位并激活了神经元，从而提供了一个快速的信号转导系统来调节IAA状态的检测。首先，将缺乏或充足的细胞在体外暴露于IAA浓度不足、不平衡或过高的培养液中，然后使用既定的方案进行运输研究。在体内，大鼠将被给予体外研究中确定的运输系统的抑制剂。逆转IAA诱导的大鼠厌食症将验证该系统在提供IAA状态识别的机制中的作用。

The long-term goals of this research are to determine the mechanisms in the brain with which disruptions of indispensable amino acid (IAA) homeostasis are recognized by omnivores, including humans. The specific aims are 1) to determine if IAA transport can activate neurons in vitro, and 2) to characterize these IAA transporters at the molecular level in vitro, and at the functional level, using appropriate transport inhibitors, via in vivo feeding studies in the rat. Disorders of IAA nutrition and metabolism are serious human health concerns, and often cause debilitating anorexia. This work is important for human health in that determination of the cellular responses to disruptions of IAA nutrition can lead to suggestions for medical intervention. The feeding (anorectic) responses to dietary IAA disproportion have been well studied, but it is not known how the brain acts in this recognition. We hypothesize that exchange of ions for IAA at the neuronal cell membrane alters the membrane potential and activates neurons, to provide a rapid transduction system mediating the detection of IAA status. First, deficient or replete cells will be exposed in vitro to media having deficient, imbalanced or excess IAA concentrations, and then subjected to transport studies, using established protocols. In vivo, rats will be given inhibitors of the transport systems determined in the in vitro studies. Reversal of IAA-induced anorexia in the rats will validate that system's role in the mechanism that provides recognition of IAA status.