Role of neuroestradiol in regulation of the GnRH surge

摘要/概要 本提案的总体目标是研究促性腺激素释放激素的调节 （GnRH）神经元在非人类灵长类动物。促性腺激素释放激素从下丘脑释放， 生殖功能通过垂体促性腺激素。拟议的研究旨在揭示 促性腺激素释放激素高峰中的神经雌二醇。 多年来已经证明，从卵巢释放的循环E2促进学习和记忆， 保护神经元免于神经元细胞死亡，并调节生殖功能。然而，最近，一个新的 关于E2的作用的概念，在大脑中局部合成和释放，作为神经调节剂， 功能，已经出现。事实上，我们的初步数据表明E2在茎中合成和释放- 下丘脑的正中隆起（S-ME）似乎是促性腺激素完全激增所必需的。的 苯甲酸雌二醇（EB）诱导的卵巢切除（OVX）雌猴LH峰显著减弱 在芳香酶阻断剂来曲唑的存在下。芳香化酶是合成E2所必需的酶， 雄激素和来曲唑是芳香酶合成的常用竞争性阻断剂。拟议 项目，我们将测试的中心假设，神经雌二醇，合成和释放在下丘脑 在排卵前GnRH释放的调节中起关键作用。提出了三个具体目标。目标1将 检验神经雌二醇是雌激素正反馈影响的一个组成部分这一假设， GnRH释放在目标1中，我们将评估EB诱导的LH峰期间神经雌二醇增加的时间 使用来曲唑注射液作为工具，并测量LH释放的变化。目标2将检验以下假设： 在EB诱导的GnRH激增过程中，神经雌二醇增加是持续性GnRH释放的基础机制。 促性腺激素释放激素的升高。在目标2中，我们将测量雌二醇和GnRH的释放以及循环LH 和E2在EB处理的OVX猴中使用微透析方法和连续血液采样， 用液相色谱-质谱法（LC/MS/MS）和RIA分析。目标3将检验假设 下丘脑芳香化酶活性在体内排卵前GnRH激增期间增加。可视化 芳香化酶，我们将使用正电子发射断层扫描（PET），以11 C-标记的西曲唑作为标记物。 这项研究有很大的潜力证明下丘脑合成的E2增加， 体内排卵前促性腺激素激增期间。反过来，这一发现将修改目前公认的 卵巢起源的E2单独控制下丘脑-垂体-性腺轴的教条。

Abstract/Summary The overall objective of this proposal is to investigate the regulation of gonadotropin-releasing hormone (GnRH) neurons in the non-human primate. GnRH is released from the hypothalamus and controls reproductive function through pituitary gonadotropins. The proposed studies are designed to uncover the role of neuroestradiol in the preovulatory GnRH surge. It has been shown for many years that circulating E2 released from the ovaries facilitates learning and memory, protects neurons from neuronal cell death, and regulates reproductive function. However, more recently, a new concept regarding the role of E2, synthesized and released locally in the brain, as a neuromodulator of neural functions, has emerged. In fact, our preliminary data indicate that E2 synthesized and released in the stalk- median eminence (S-ME) of the hypothalamus appears to be necessary for the full gonadotropin surge. That is, estradiol benzoate (EB)-induced LH surge in ovariectomized (OVX) female monkeys was greatly attenuated in the presence of the aromatase blocker letrozole. Aromatase is the enzyme necessary for E2 synthesis from androgens and letrozole is a commonly used competitive blocker for aromatase synthesis. In the proposed project, we will test the central hypothesis that neuroestradiol, synthesized and released in the hypothalamus plays a critical role in regulation of preovulatory GnRH release. Three Specific Aims are proposed. Aim 1 will test the hypothesis that neuroestradiol is an integral part of the estrogen's positive feedback influence on GnRH release. In Aim 1, we will assess the timing of neuroestradiol increases during the EB-induced LH surge using letrozole injection as a tool and measuring the changes in LH release. Aim 2 will test the hypothesis that neuroestradiol increases during the EB-induced GnRH surge are an underling mechanism of the sustained elevation of GnRH release. In Aim 2 we will measure release of estradiol and GnRH as well as circulating LH and E2 in EB treated OVX monkeys using a microdialysis method and serial blood sampling followed by analysis with liquid chromatography-mass spectrometry (LC/MS/MS) and RIA. Aim 3 will test the hypothesis that aromatase activity in the hypothalamus increases during the preovulatory GnRH surge in vivo. To visualize aromatase we will use positron emission tomography (PET) scan with 11C-labeled cetrozole as a marker. The proposed study has great potential to demonstrate that E2 synthesized in the hypothalamus increases during the preovulatory gonadotropin surge in vivo. In turn, this finding will modify the presently accepted dogma that E2 of ovarian origin solely controls the hypothalamo-pituitary-gonadal axis.