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）信号控制稳态的机制。已经表明，经典的雌激素受体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，负责E2在中枢神经系统（CNS）中的所有作用。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，导致下丘脑阿黑皮素原（POMC）神经元的兴奋性增加和新的基因转录。我们已经开发了mER选择性配体STX，并且E2和STX在雌激素受体和GPR 30敲除小鼠中完全有效。此外，作为原理证明，与E2类似，用STX进行体内处理可减弱低雌激素雌性豚鼠的体重增加。虽然已知瘦素和胰岛素输入到POMC和神经肽Y（NPY）神经元对于能量稳态是重要的，但是E2调节促食欲POMC和促食欲NPY神经元中瘦素和胰岛素信号传导的细胞机制相对未被探索。需要进一步的研究来表征的串扰的mER与其他激素信号通路在POMC神经元和它的作用，在调节其他下丘脑（NPY）神经元参与控制能量稳态的兴奋性。因此，我们目前的工作集中在下丘脑弓状POMC和NPY神经元，其中E2通过多个信号级联反应。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、组织化学和整体动物生理学）。我们的工作假设是，E2的兴奋作用部分是由于除了POMC和NPY神经元中的ER（和ER）外，还激活了mER，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促食欲和促食欲神经元中协同作用。因此，我们的具体目标是：（1）阐明E2和STX对POMC神经元瘦素信号的影响;（2）表征E2和STX对NPY神经元胰岛素和瘦素信号的影响;（3）阐明POMC对NPY神经元的输入;以及（4）在排卵周期的早期和晚期卵泡阶段，在豚鼠POMC和NPY神经元中表征瘦素和胰岛素信号传导。了解E2的这些新作用将为E2在绝经状态中的基本作用提供重要的见解，并允许进一步开发新的雌激素化合物，特别是针对这些参与控制稳态的关键脑回路。

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.