ALTERATIONS IN ESTROGEN METABOLISM CAUSED BY EXPOSURE TO PCBS

这项研究的广泛的长期目标是确定 第一阶段和第二阶段的多氯联苯（PCBs）接触情况 17 β-雌二醇（E2）在肝脏和肝外组织中的代谢。 人类接触多氯联苯可能会导致不同的终点， 智力发展和生育能力下降的影响。 的改变 暴露于多氯联苯的雌激素代谢是一种机制， 外源性物质可改变生育力、生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，在一个同源特定的方式，多氯联苯将增加 肝脏和雌激素靶点中E2羟基化和结合率 组织，在某些情况下，异常的雌激素代谢会导致 氧化应激 我们的具体目标是： (1)为了确定暴露于多氯联苯（Aroclor 1248和几种 单个同系物）对细胞色素P450催化的羟基化速率的影响 的E2。 从多氯联苯的肝、肾、子宫和脑中制备微粒体， 女性暴露率和来自人源性乳腺、肝脏、肾脏和 体外暴露于PCB的子宫细胞将用于E2代谢 问题研究 (2)确定接触多氯联苯对第二阶段的影响， E2在肝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和雌激素 将用制备的微粒体测定磺基转移酶活性 从暴露于多氯联苯的雌性大鼠的组织中提取的细胞， 体外 将确定雌激素和甲状腺激素， T3和T4是相同缀合酶的底物。 (3)为了确定暴露于PCGs对表达的影响， CYP 1A的细胞色素P450和最近发现的CYP 1B基因 亚家族 免疫化学技术，RNA印迹，以及相反的 转录酶-聚合酶链反应将用于表征基因 在雌性大鼠体内组织和人乳腺中的表达， 肾和子宫内膜细胞。 (4)确定PCB暴露和PCB诱导的雌激素的影响 代谢对雌性大鼠和人体组织中氧化应激的影响 体外培养乳腺细胞 脂质过氧化物，DNA链断裂， 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.