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动物在大脑中识别必需氨基酸（IAA）稳态破坏的机制。具体目的是1)确定IAA转运是否可以在体外激活神经元，2)通过大鼠体内喂养研究，在体外分子水平和功能水平上表征这些IAA转运蛋白，并使用适当的转运抑制剂。IAA营养和代谢紊乱是严重的人类健康问题，经常导致衰弱性厌食症。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导致医疗干预的建议。进食（厌食）对饮食中IAA比例失调的反应已经得到了很好的研究，但人们还不知道大脑是如何识别这种反应的。我们假设IAA离子在神经元细胞膜上的交换改变了膜电位并激活了神经元，从而提供了一个介导IAA状态检测的快速转导系统。首先，将缺乏或充满的细胞在体外暴露于IAA浓度不足、不平衡或过量的培养基中，然后使用既定的方案进行转运研究。在体内，大鼠将被给予在体外研究中确定的运输系统抑制剂。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.