Neurobiology for Lac-Phe Hypophagia

项目摘要 有规律的身体活动是一种强有力的干预措施，可以减少肥胖， 肥胖相关的代谢性疾病。其机制尚不完全清楚，但很可能 而不仅仅是与活动相关的能量消耗增加。我们最近发现了一个 称为N-乳酰-苯丙氨酸（“Lac-Phe”）的乳酸盐衍生代谢物是最显著升高的 在激烈的运动回合后血浆中的代谢物。我们进一步证明了药理学 升高血浆Lac-Phe以模拟运动训练可以有力地抑制肥胖小鼠的进食， 重复Lac-Phe方案导致慢性食欲减退、体重减轻和肥胖减少，与 改善葡萄糖耐量。虽然这些发现提高了Lac-Phe可以用作药物的可能性， 尽管Lac-Phe是一种抗肥胖剂，但Lac-Phe食欲减退的神经生物学机制仍不清楚。我们 初步的研究发现，Agouti-related peptide（AgRP）表达神经元位于丘脑弓状核， 下丘脑（ARH）是Lac-Phe作用的直接靶点之一，并介导其下吞反应。一 目的是研究Lac-Phe和运动对AgRP神经元传入突触的影响， 从AgRP神经元到其突触靶的传出输出。我们的数据还表明，Lac-Phe抑制 AgRP神经元通过增加外向钾电流，即KATP电流而产生食欲。因此第二 目的是使用CRISPR-Cas9方法在基因上破坏KATP通道亚基的表达， AgRP神经元，并使用这些模型来确定KATP通道在Lac-Phe诱导的 AgRP抑制和食欲减退。最后，我们还观察到Lac-Phe激活了其他四个大脑中的神经元， 区域，外侧隔（LS），下丘脑室旁核（PVH），臂旁核 孤束核（NTS）。因此，我们将联合收割机与 活性群体（TRAP）方法与电生理学，化学遗传学和scRNA-Seq，以确定 Lac-Phe是否直接或间接刺激这些神经元，这些神经元是否在功能上参与 在Lac-Phe诱导的食欲减退中，这些Lac-Phe激活的神经元的神经化学特性是什么。 这些拟议的实验将揭示Lac-Phe摄食不足的神经生物学基础，这可能会识别出 Lac-Phe或相关途径作为体重管理的目标。

PROJECT SUMMARY Regular physical activity is a powerful intervention that reduces obesity and confers protection against obesity-associated metabolic diseases. The mechanisms responsible are incompletely understood but are likely to extend beyond activity-associated increases in energy expenditure alone. We recently identified a lactate-derived metabolite called N-lactoyl-phenylalanine (“Lac-Phe”) as the most significantly elevated metabolite in blood plasma after an intense exercise bout. We further demonstrated that pharmacological elevation of plasma Lac-Phe to mimic exercise training can robustly suppress feeding in obese mice, and repeated Lac-Phe regimen results in chronic hypophagia, weight loss, and reduced adiposity, associated with improved glucose tolerance. While these findings raise the possibility that Lac-Phe could be used as an anti-obesity agent, the neurobiological mechanisms underlying Lac-Phe hypophagia remains unknown. Our preliminary studies identified Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus of the hypothalamus (ARH) as one direct target of Lac-Phe action and mediate its hypophagic response. One objective is to examine effects of Lac-Phe and exercise on afferent synaptic inputs to AgRP neurons, and efferent outputs from AgRP neurons to their synaptic targets. Our data also suggest that Lac-Phe inhibits orexigenic AgRP neurons via increasing an outward potassium current, namely KATP current. Thus, the second objective is to use the CRISPR-Cas9 approach to genetically disrupt the expression of KATP channel subunits in AgRP neurons, and use these models to determine the functional relevance of KATP channel in Lac-Phe-induced AgRP inhibition and hypophagia. Finally, we also observed that Lac-Phe activates neurons in four other brain regions, the lateral septum (LS), the paraventricular nucleus of the hypothalamus (PVH), the parabrachial nucleus (PBN), and the nucleus of solitary tract (NTS). Thus, we will combine the Targeted Recombination in Active Populations (TRAP) approach with electrophysiology, chemogenetics and scRNA-Seq to determine whether Lac-Phe stimulates these neurons directly or indirectly, whether these neurons functionally participate in the Lac-Phe-induced hypophagia, and what are neurochemical identities of these Lac-Phe-activated neurons. These proposed experiments will reveal the neurobiological basis for Lac-Phe hypophagia, which may identify Lac-Phe or the associated pathways as targets for weight management.