Hypothalamic leptin and insulin signals aligning metabolic state and fertility

描述（由申请人提供）：美国儿童和青少年肥胖症的急剧增加对下一代的健康造成严重后果。沿着众所周知的健康风险，儿童肥胖症损害生殖健康和发育。事实上，女孩肥胖的早期发病，特别是在青春期，有利于月经不规则，慢性无排卵，不孕症和PCOS在成年期的发展。虽然这种关系的主要原因是不确定的，对胰岛素和瘦素的中枢抵抗，肥胖的循环标志物，似乎抑制生殖轴。然而，代谢系统和生殖系统之间的关键通信点仍然不清楚。 该提案旨在推进我们阐明代谢性不孕症的分子和遗传决定因素的长期目标。我们假设瘦素和胰岛素直接作用于下丘脑POMC和NPY/AgRP神经元，这些神经元为GnRH神经元提供输入。这一假说基于以下发现：POMC和NPY/AgRP神经元对瘦素和胰岛素的反应活性改变似乎依赖于磷脂酰肌醇3-激酶（PI 3 K）细胞内信号通路。此外，先前的研究表明，脑特异性瘦素受体和胰岛素受体敲除对生殖轴有显著影响，但通过非PI 3 K途径阻止瘦素受体信号传导不会损害生育能力。因此，我们的研究将确定胰岛素和瘦素信号通过PI 3 K是否需要正常的（1）能量稳态和（2）生殖功能和POMC神经元和/或NPY/AgRP神经元。 为了实现这些目标，我们将使用cre/lox系统遗传靶向关键神经元。具体来说，我们将研究缺乏胰岛素和瘦素受体或功能性PI 3 K的小鼠的代谢和生殖表型，仅在POMC神经元和仅在NPY/AgRP神经元。然后，我们将使用电生理学和一种新的方法可视化Akt信号在体外，以确定PI 3 K缺失对神经元功能的影响。总的来说，这些数据可能为治疗和预防肥胖相关不孕症的治疗进展提供新的靶点。 项目叙述：希尔博士在生殖和代谢的不同领域的背景，是唯一有资格进行这些研究。在她的博士后研究期间组装的新的遗传方法将是调查相互作用的下丘脑代谢和生殖途径的未充分研究领域的有力工具。通过为她向研究独立过渡提供一个工具，该提案为专注于生殖健康的研究计划奠定了基础，并发现了治疗营养和肥胖相关不孕症的新方法。

DESCRIPTION (provided by applicant): The dramatic increases in childhood and adolescent obesity in the U.S. have serious consequences for the health of the next generation. Along with its well-known health risks, childhood obesity impairs reproductive health and development. Indeed, early onset of obesity in girls, particularly during adolescence, favors the development of menses irregularities, chronic anovulation, infertility, and PCOS in adulthood. While the primary cause of this relationship is uncertain, central resistance to insulin and leptin, circulating markers of adiposity, appears to inhibit the reproductive axis. The key sites of communication between the metabolic and reproductive systems, however, remain unclear. This proposal is designed to advance our long-term goal of elucidating the molecular and genetic determinants of metabolic infertility. We hypothesize that leptin and insulin act directly on hypothalamic POMC and NPY/AgRP neurons that provide input to GnRH neurons. This hypothesis rests on findings that altered activity of POMC and NPY/AgRP neurons in response to leptin and insulin appear to depend on the phosphatidylinositol 3-kinase (PI3K) intracellular signaling pathway. In addition, previous studies have shown that brain-specific leptin receptor and insulin receptor knockouts have dramatic effects on the reproductive axis, but preventing leptin receptor signaling through non-PI3K pathways does not impair fertility. Thus, our studies will determine if insulin and leptin signaling through PI3K is required for normal (1) energy homeostasis and (2) reproductive functioning and in POMC neurons and/or in NPY/AgRP neurons. To accomplish these goals, we will genetically target the critical neurons using the cre/lox system. Specifically, we will examine the metabolic and reproductive phenotype of mice lacking insulin and leptin receptors or functional PI3K only in POMC neurons and only in NPY/AgRP neurons. We will then use electrophysiology and a novel method of visualizing Akt signaling in vitro to determine the impact of PI3K deletion on neuronal function. Collectively, these data may provide a new target for therapeutic advances in the treatment and prevention of obesity-related infertility. Project Narrative: With a background in the diverse fields of reproduction and metabolism, Dr. Hill is uniquely qualified to undertake these studies. The novel genetic approaches assembled during her post-doctoral fellowship will be powerful tools for investigating the understudied area of interacting hypothalamic metabolic and reproductive pathways. By providing a vehicle for her transition to research independence, this proposal lays the groundwork for a research program focused on reproductive health and the discovery of new approaches for treating nutritional and obesity-related infertility.