STEROIDS /VASCULAR REACTIVITY /NITRIC OXIDE PRODUCTION

描述（改编自申请人的描述）：这些的总体目标 研究的目的是检验以下假设： 肾上腺皮质激素分泌增加， 怀孕期间的雌激素是控制正常血压所必需的 在围产期。 在妊娠、皮质激素过少母羊和 在患有肾上腺皮质功能减退症的孕妇中的临床经验表明， 正常的血压控制在怀孕后期需要增加肾上腺 分泌物皮质醇供应不足导致快速和深刻的 低血压，母亲和胎儿的发病率和死亡率增加。 本提案中的实验将直接检验以下假设： 在雌激素增加的同时皮质醇减少会导致更大的 降低血管对苯肾上腺素的反应性，这与 增加的一氧化氮产生在一个或多个位点中， 身体 将研究四组母羊：肾上腺切除组、卵巢切除组 母羊，肾上腺切除卵巢切除母羊，雌二醇，肾上腺- 完整卵巢切除母羊和肾上腺完整卵巢切除母羊 雌二醇所有切除肾上腺的母羊将接受醛固酮治疗， 皮质醇一周后手术，然后肾上腺类固醇 将停止输液以产生肾上腺功能减退状态。动物将 研究的时间点（8小时），其中肾上腺切除雌激素 治疗的动物是肿胀的，但肾上腺切除母羊没有 雌二醇治疗不是明显的过度治疗。实验将测试 在所有4组母羊中， 检验雌激素给药降低血管反应性的假设 在切除肾上腺的母羊中。实验还将测定血浆中 硝酸盐和亚硝酸盐和L-NAME的输注能力， 一氧化氮合酶（NOS），以增加血管反应性， 肾上腺切除母羊与雌二醇治疗。实验还将测试 cGMP的浓度，以及iNOS、eNOS和nNOS蛋白的水平， 主动脉、子宫动脉、肠系膜中的Western分析和RT-PCR mRNA 动脉、肾动脉、肾小叶间动脉、肾髓质和皮质，以及 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NOS的增加， 一个或多个这样的网站。组织样本也将由 免疫组化以更精确地鉴定细胞群 在这些母羊中含有iNOS、eNOS或nNOS。因此，这些实验将 描述皮质醇改变NOS的亚型和细胞 戒断，单独或与增加的雌激素组合。这 这些信息将构成未来实验的基础，以确定 雌激素和皮质醇相互作用控制NO和 怀孕期间的血压调节。这些研究将 增加了我们对怀孕期间正常血压控制的理解， 以及足月时肾上腺皮质功能减退的病理生理学。这些研究将 也有助于我们理解， 皮质醇和增加雌激素控制正常血压 怀孕

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.