ALTERATIONS IN ESTROGEN METABOLISM CAUSED BY EXPOSURE TO PCBS

这项研究的广泛、长期的目标是确定 在第一阶段和第二阶段接触多氯联苯 17β-雌二醇在肝脏和肝外组织中的代谢。 人类接触多氯联苯可能导致不同的终点，如损害 智力发展和生育率下降。更改的内容 暴露于多氯联苯的雌激素代谢是一种机制，通过这种机制 外源生物可能改变生育力、繁殖力和神经内分泌发育 通过破坏正常的雌激素信号转导。我们 假设，以同类物质特有的方式，多氯联苯将增加 肝脏和雌激素靶区的雌二醇羟化和结合速率 组织，在某些情况下，雌激素代谢异常会导致 氧化应激。 我们的具体目标是： (1)确定接触多氯联苯的影响(Aroclor 1248和几个 单个同系物)对细胞色素P450催化羟化的速率 雌二醇组。从多氯联苯的肝、肾、子宫和脑中制备的微生物体- 暴露的女性比率和来自人类来源的乳房、肝脏、肾脏和 体外暴露于多氯联苯的子宫细胞将用于E2代谢 学习。 (2)确定接触多氯联苯对第二阶段的影响 E2在肝脏和肝外组织中的代谢。雌激素 葡萄糖醛酸基转移酶、T3和T4葡萄糖醛酸基转移酶与雌激素 用制备的微粒体法测定磺基转移酶的活性 从暴露于多氯联苯的雌性大鼠的组织中分离出人类来源的细胞 体外培养。将确定雌激素和甲状腺激素是否， T3和T4是相同结合酶的底物。 (3)确定暴露于PCGs后对其表达的影响。 细胞色素P450与新近发现的细胞色素P1B基因 子族。免疫化学技术、RNA印迹和反向 将使用转录酶-聚合酶链式反应来表征基因 在雌性大鼠体内组织和人乳房中表达， 肾脏和体外培养的子宫内膜细胞。 (4)确定多氯联苯暴露和多氯联苯诱导的雌激素的影响 氧化应激在雌性大鼠和人组织中的代谢 乳房细胞的体外培养。过氧化脂质，DNA链断裂，以及 DNA中8-羟基鸟嘌呤的存在将被测量为 氧化应激。

The broad, long-term objective of this research is to determine the effects of exposure to polychlorinated biphenyls (PCBs) on the phase I and phase II metabolism of 17beta-estradiol (E2) in liver and extrahepatic tissues. Human exposure to PCBs may result in diverse endpoints such as impairment of intellectual development and reduced fertility. The alteration of estrogen metabolism by exposure to PCBs is a mechanism by which these xenobiotics may alter fertility, fecundity, and neuroendocrine development through disruption of normal estrogenic signal transduction. We hypothesize that, in a congener-specific manner, PCBs will increase the rates of E2 hydroxylation and conjugation in liver and in estrogen target tissues, and under some conditions aberrant estrogen metabolism will cause oxidative stress. Our Specific Aims are: (1) To determine the effects of exposure to PCBs (Aroclor 1248 and several individual congeners) on the rates cytochrome P450-catalyzed hydroxylation of E2. Microsomes prepared from liver, kidney,uterus, and brain of PCB- exposed female rates and from human-derived breast, liver, kidney, and uterine cells exposed to PCBs in vitro will be used for the E2 metabolism studies. (2) To determine the effects of exposure to PCBs on the phase II metabolism of E2 in liver and extrahepatic tissues. Estrogen glucuronsyltransferase, T3 and T4 glucuronosyltransferase, and estrogen sulfotransferase activities will be determined with microsomes prepared from tissues of PCB-exposed female rats and with human-derived cells in vitro. It will be determined whether estrogens and the thyroid hormones, T3 and T4, are substrates for the same conjugating enzymes. (3) To determine the effects of exposure to PCGs on the expression of cytochrome P450s of the CYP1A and the recently discovered CYP1B gene subfamilies. Immunochemical techniques, RNA blots, and the reverse transcriptase-polymerase chain reaction will be used to characterize gene expression in tissues of the female rat in vivo and in human breast, kidney, and endometrial cells in vitro. (4) To determine the effects of PCB exposure and PCB-induced estrogen metabolism on oxidative stress in tissues of the female rat and in human breast cells in vitro. Lipid peroxides, DNA strand breaks, and the presence of 8-hydroxyguanine in DNA will be measured as evidence of oxidative stress.