Estrogen Influences on Fetal Adrenocorticotropin

描述（由申请人提供）：在本实验室进行的实验的总体目标是确定控制胎羊下丘脑-垂体-肾上腺（HPA）轴活动的机制。更全面地了解下丘脑轴的活动将是理解胎儿应激、体内平衡和（在绵羊和其他物种中）分娩控制的关键。在过去的几年里，我们研究了几种控制绵羊胎儿HPA轴活性的生理和内分泌机制。最近，我们报道了雌激素能有效刺激胎儿HPA轴的活动。目前的建议是更全面地研究这种内分泌相互作用：阐明脑前列腺素作为这种相互作用的介质的作用。具体来说，我们提出了两个总体目标：1)阐明发育和内源性雌激素对脑前列腺素的自发（预备）作用；2)阐明外源性雌激素对脑类前列腺素的影响：阐明雌激素对胎儿中枢神经系统前列腺素内过氧化物合成酶（PGHS）同工型的影响，证明雌激素刺激的前列腺素合成介导了雌激素对胎儿ACTH分泌的影响。为了实现这些目标，我们将使用体内、生化和分子技术来研究前列腺素生物合成系统在mRNA、蛋白质和翻译后加工水平上的作用。所有的实验都将基于对慢性导尿胎羊HPA轴控制的研究。为第一个目标设计的实验将包括测量胚胎羊在雌激素处理下脑PGHS-1和PGHS-2丰度和脑前列腺素产生的变化，以及其他实验，将测试内源性雌激素合成阻断对HPA控制、PGHS异构体表达和脑内前列腺素生成的影响。为第二个目的设计的实验将揭示雌激素刺激HPA功能所需的天数。为第二个目的设计的实验将研究外源性（生理）雌激素管理对PGHS-1和PGHS-2表达、翻译后加工以及与任一已知形式的雌激素受体共定位的影响。

DESCRIPTION (provided by applicant): The overall goal of the experiments performed in this laboratory are to identify the mechanisms controlling the activity of the hypothalamus-pituitary-adrenal (HPA) axis in fetal sheep. Providing a more complete understanding of the activity of the HPA axis will be key to understanding fetal stress, homeostasis, and (in sheep and perhaps in other species) the control of parturition. In past years, we have investigated several of the physiological and endocrine mechanisms controlling the activity of the ovine fetal HPA axis. Recently, we have reported that estrogen potently stimulates the activity of the fetal HPA axis. The present proposal is to investigate this endocrine interaction more completely: to elucidate the role of brain prostanoids as mediators of this interaction. Specifically, we propose two general aims: 1) to elucidate the spontaneous (preparturient) effects of development and endogenous estrogens on brain prostanoids; and 2) to elucidate the effects of exogenous estrogen on brain prostanoids: to elucidate the influence of estrogen on prostaglandin endoperoxide synthase (PGHS) isoforms in the fetal central nervous system and to demonstrate that estrogen-stimulated prostaglandin synthesis mediates the effect of estrogen on fetal ACTH secretion. To achieve these aims, we will perform experiments using in vivo, biochemical, and molecular techniques designed to study the prostaglandin biosynthesis system at the mRNA, protein, and posttranslational processing levels. All of the experiments will be based on the study of the HPA axis control in chronically-catheterized fetal sheep. Experiments designed for the first aim will include the measurement of brain PGHS-1 and PGHS-2 abundance and brain prostanoid production in response to estrogen treatment of fetal sheep, and other experiments which will test the effect of blockade of endogenous estrogen synthesis on HPA control, expression of PGHS isoforms and generation of prostaglandins within the brain. Experiments designed for the second aim will reveal the number of days required for estrogen stimulation of HPA function. Experiments designed for the second aim will investigate the effect of exogenous (physiological) estrogen administration on PGHS-1 and PGHS-2 expression, posttranslational processing, and colocalization with either known forms of the estrogen receptor.