STEROIDS /VASCULAR REACTIVITY /NITRIC OXIDE PRODUCTION

描述(改编自申请者的描述)：这些项目的总体目标 研究的目的是检验这样一种假设，即 肾上腺皮质类固醇分泌增加和肾上腺皮质激素分泌增加 孕期雌激素是控制正常血压所必需的 在围产期。对怀孕、皮质醇减退母羊和 妊娠合并肾上腺皮质功能减退症的临床经验提示 妊娠晚期正常血压控制需要增加肾上腺皮质 分泌物。皮质醇供应不足导致迅速而深刻的 低血压，母亲和胎儿的发病率和死亡率都增加了。 这个方案中的实验将直接测试一个假设 雌激素增加时皮质醇减少会导致更大的 血管对苯肾上腺素的反应性降低，这与 中国一个或多个地点的一氧化氮产量增加 尸体。将对四组母羊进行研究：去肾上腺、去卵巢 去肾上腺的母羊，去卵巢的母羊用雌二醇，肾上腺- 完整去卵巢的母羊和肾上腺完整的去卵巢的母羊 加了雌二醇。所有切除肾上腺的母羊都将接受醛固酮和 术后一周服用皮质醇，然后使用肾上腺类固醇 输液将被停止，以产生肾上腺皮质功能低下状态。动物将会是 在肾上腺切除雌激素的时间点(8小时)进行研究 经过处理的动物血压较低，但去肾上腺的母羊没有 雌二醇治疗并不明显降低血压。实验将测试 4组母羊对苯肾上腺素反应的血管反应性 检验雌激素可降低血管反应性的假说 在去肾上腺的母羊身上。实验还将确定血浆中的 硝酸盐和亚硝酸盐与血管紧张素转换酶抑制剂L的输注能力 一氧化氮合酶(NOS)，以增加血管的反应性 去肾上腺的母羊，用雌二醇治疗。实验还将测试 CGMP浓度以及iNOS、eNOS和nNOS蛋白水平的测定 主动脉、子宫动脉、肠系膜组织的RT-PCR和Western分析及基因表达 动脉、肾动脉、肾小叶间动脉、肾髓质和肾皮质 骨骼肌，取自相同4个实验组的动物。这些 实验将确定皮质醇的缺乏是否会导致脑内一氧化氮合酶的增加 这些网站中的一个或多个。组织样本也将通过 免疫组织化学以更准确地识别细胞群体 在这些母羊体内含有iNOS、eNOS或nNOS。因此，这些实验将 描述皮质醇改变一氧化氮合酶的异构体(S)以及在哪些细胞中 停药，要么单独停药，要么合并雌激素增加。这 这些信息将成为未来实验的基础，以确定 雌激素和皮质醇相互作用控制NO和 孕期血压的调节。因此，这些研究将 增加了我们对怀孕期间正常血压控制的理解， 以及足月肾上腺皮质功能减退症的病理生理学。这些研究将 也有助于我们理解增加的平衡效应 皮质醇和雌激素升高在正常血压控制中的作用 怀孕了。

DESCRIPTION (Adapted from applicant's description): The overall goal of these studies is to test the hypothesis that there is an interaction between increased secretion of adrenal corticosteroids and increased secretion of estrogen during pregnancy which is necessary for normal blood pressure control in the peripartal period. Studies in pregnant, hypocorticoid ewes and clinical experience in pregnant women with hypoadrenocorticism suggest that normal blood pressure control in late pregnancy requires increased adrenal secretion. Insufficient supply of cortisol results in rapid and profound hypotension, with increased morbidity and mortality in both mother and fetus. The experiments in this proposal will directly test the hypothesis that a decrease in cortisol at a time of increased estrogen results in a greater decrease in vascular reactivity to phenylephrine and that this correlates with increased production of nitric oxide production in one or more sites in the body. Four groups of ewes will be studied: adrenalectomized, ovariectomized ewes, adrenalectomized ovariectomized ewes treated with estradiol, adrenal- intact ovariectomized ewes, and adrenal-intact ovariectomized ewes treated with estradiol. All adrenalectomized ewes will be treated with aldosterone and cortisol for one week following surgery, and then the adrenal steroid infusions will be stopped to produce the hypoadrenal state. Animals will be studied at a time point (8 hours) in which the adrenalectomized estrogen treated animals are hypotensive, but the adrenalectomized ewes without estradiol treatment are not overtly hypotensive. Experiments will test vascular reactivity in response to phenylephrine in all 4 groups of ewes to test the hypothesis that estrogen administration decreases vascular reactivity in adrenalectomized ewes. Experiments will also determine plasma levels of nitrates and nitrites and the ability of infusion of L-NAME, an inhibitor of nitric oxide synthase (NOS), to increase vascular reactivity in adrenalectomized ewes with estradiol treatment. Experiments will also test the concentrations of cGMP, and levels of iNOS, eNOS, and nNOS protein measured by Western analysis and mRNA by RT-PCR in aorta, uterine artery, mesenteric artery, renal artery, renal interlobular artery, renal medulla and cortex, and skeletal muscle, taken from animals in the same 4 experimental groups. These experiments will determine if absence of cortisol results in increased NOS in one or more of these sites. Samples of tissue will also be examined by immunohistochemistry to more precisely identify the cell populations containing iNOS, eNOS or nNOS in these ewes. These experiments will therefore describe which isoform(s), and in which cells, NOS is altered by cortisol withdrawal, either alone or in combination with increased estrogen. This information will form the basis of future experiments to determine the mechanism of the interaction of estrogen and cortisol in control of NO and regulation of blood pressure during pregnancy. These studies will therefore add to our understanding of normal blood pressure control during pregnancy, and of the pathophysiology of hypoadrenocorticism at term. These studies will also to our understanding of the counterbalancing effects of increased cortisol and increased estrogens in control of normal blood pressure in normal pregnancy.