Beta Endorphin Neurons and the Control of Homeostasis

描述（由申请人提供）：拟议研究的长期目标是阐明下丘脑神经元中17 -雌二醇（E2）信号控制体内平衡的机制。研究表明，E2在中枢神经系统（CNS）中的所有作用都是由经典雌激素受体ER和ER以及可能不同的剪接变体通过快速和长期的基因组机制起作用的。然而，我们的研究表明，一种新的膜E2受体（mER）参与了一个快速的信号级联反应，导致下丘脑proopiomelanocortin （POMC）神经元的兴奋性增加和新基因转录。我们开发了一种mER选择性配体STX， E2和STX在雌激素受体和GPR30敲除小鼠中都是完全有效的。此外，作为原理证明，在体内用STX治疗，类似于E2，减轻低雌激素雌性豚鼠的体重增加。虽然已知瘦素和胰岛素对POMC和神经肽Y （NPY）神经元的输入对能量稳态很重要，但E2在缺氧POMC和缺氧NPY神经元中调节瘦素和胰岛素信号的细胞机制相对未被探索。mER与POMC神经元中其他激素信号通路的串扰及其在调节参与能量稳态控制的下丘脑（NPY）神经元兴奋性中的作用有待进一步研究。因此，我们目前的工作重点是下丘脑弓状POMC和NPY神经元，E2通过多个信号级联起作用。我们的多学科方法结合了一系列独特的细胞和分子工具以及我们的综合专业知识（即电生理学，化学，分子生物学，组织化学和全动物生理学）。我们的工作假设是E2的厌食作用部分是由于POMC和NPY神经元中除ER（和ER）外的mER的激活，最终上调POMC并下调NPY兴奋性和基因表达。此外，我们假设雌激素信号通路与瘦素和胰岛素信号通路在这些厌氧和厌氧神经元中协同作用。因此，我们的具体目的是：(1)阐明E2和STX对POMC神经元中瘦素信号传导的影响；(2)研究E2和STX对NPY神经元胰岛素和瘦素信号传导的影响；(3)阐明POMC对NPY神经元的输入；(4)研究豚鼠卵泡早期和晚期卵泡期POMC和NPY神经元中瘦素和胰岛素信号的变化。了解E2的这些新作用将为了解E2在绝经期的基本作用提供关键的见解，并允许进一步开发新的雌激素化合物，专门针对参与控制体内平衡的这些关键脑回路。

DESCRIPTION (provided by applicant): The long-range goal of the proposed research is to elucidate the mechanism (s) by which 17 -estradiol (E2) signals in hypothalamic neurons to control homeostasis. It has been suggested that the classical estrogen receptors ER and ER, and possibly different splice variants, acting through rapid and long term genomic mechanisms are responsible for all of the actions of E2 in the central nervous system (CNS). However, our studies indicate that a novel membrane E2 receptor (mER) is involved in a rapid signaling cascade that leads to increased excitability and new gene transcription in hypothalamic proopiomelanocortin (POMC) neurons. We have developed a mER selective ligand STX, and both E2 and STX are fully efficacious in estrogen receptor , and GPR30 knockout mice. Moreover as proof of principle, in vivo treatment with STX, similar to E2, attenuates the weight gain in hypo-estrogenic female guinea pigs. Although it is known that leptin and insulin inputs to POMC and neuropeptide Y (NPY) neurons are important for energy homeostasis, the cellular mechanism (s) by which E2 modulates leptin and insulin signaling in anorexigenic POMC and orexigenic NPY neurons is relatively unexplored. Further studies are needed to characterize the cross-talk of the mER with other hormone signaling pathways in POMC neurons and its role in modulating the excitability of other hypothalamic (NPY) neurons involved in the control of energy homeostasis. Therefore, our current work focuses on hypothalamic arcuate POMC and NPY neurons in which E2 acts through multiple signaling cascades. Our multidisciplinary approach incorporates a unique range of cellular and molecular tools and our combined expertise (i.e., electrophysiology, chemistry, molecular biology, histochemistry and whole animal physiology). Our working hypothesis is that the anorexic effects of E2 are due, in part, to the activation of a mER in addition to ER (and ER) in POMC and NPY neurons that ultimately up regulates POMC and down-regulates NPY excitability and gene expression. In addition, we hypothesize that estrogen signaling pathways act in concert with leptin and insulin signaling pathways in these anorexigenic and orexigenic neurons. Therefore, our specific aims are the following: (1) to elucidate the effects of E2 and STX on leptin signaling in POMC neurons; (2) to characterize the effects of E2 and STX on insulin and leptin signaling in NPY neurons; (3) to elucidate the POMC input to NPY neurons; and (4) to characterize leptin and insulin signaling in guinea pig POMC and NPY neurons during the early and late follicular phases of the ovulatory cycle. Understanding these novel actions of E2 will provide critical insight into the fundamental role of E2 withdrawal in menopausal states and allow the further development of new estrogenic compounds specifically targeting these critical brain circuits involved in the control of homeostasis.