| 题名 | 相同和不同作用机制雌激素系统干扰物的联合毒性 |
| 作者 | 杨蓉 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 马梅 ; 王子健 |
| 关键词 | 雌激素，抗雌激素，浓度加和，作用方式，模型预测，Estrogens Antiestrogens Concentration addition Mode of action Model prediction |
| 其他题名 | Combined Effects of Estrogenic and Antiestrogenic Pollutants with the Same or Different Mechanisms of Action |
| 学位专业 | 环境科学 |
| 中文摘要 | 环境内分泌干扰物是一类可干扰生物生殖、成长、行为及体内维持平衡所需的激素的合成、分泌、运输、结合、作用及消除过程的外源性物质。数量和种类众多的内分泌干扰物通过各种途径进入环境，在低浓度下即可对暴露其中的生物体产生不良影响，还产生由加和或相互作用导致的联合效应。因此，环境内分泌干扰物联合作用的描述和预测就显得尤为重要。本研究利用两种高通量离体生物测试，从受体结合、细胞增殖和基因表达水平干扰等不同层次评价了环境内分泌干扰物中最受关注的雌激素受体干扰物的联合作用，并比较了混合物毒性研究中两个重要模型——浓度加和和效应加和的预测能力。 受体结合是雌激素受体干扰物重要的作用方式之一。在受体结合层面上，针对雌激素和类雌激素的联合效应，利用等毒性配比设计和随机混合设计配制了31个最多含九种雌激素物质组分的混合物，通过重组基因双杂交酵母测试评价其联合毒性，并比较浓度加和模型和效应加和模型的预测结果。结果表明，针对具有单一作用方式的双杂交酵母测试，浓度加和模型和衍生的雌二醇当量法可以 较精确地描述混合物的联合作用，且不受混合物组成、组分浓度和作用强度的影响。针对雌激素和抗雌激素的联合效应，配制 15个由三种雌激素和三种抗雌激素遵循固定比例设计的混合物。通过添加其亚最大效应浓度的标准雌激素17β-雌二醇进行拮抗效应检测，发现抗雌激素混合物的联合效应可由浓度加和模型和他莫昔芬当量这一概念描述和表征。当雌激素和抗雌激素共同作用时，抗雌激素 的存在可降低雌激素响应，造成毒性评价中生物测试对雌激素效应的低估，但此影响可以通过公式修正和策略选择基本消除。 在细胞增殖层面上，由于雌激素受体干扰物可通过多种作用方式导致增殖，联合作用的表现可能与受体结合不同。因此，利用对雌激素暴露敏感的人乳腺癌细胞MCF-7进行雌激素混合物的联合效应研究。结果表明，17β-雌二醇和双酚A通过等毒性配比获得的二元混合物诱导MCF-7细胞增殖呈现拮抗效应，这与E2和BPA通过不同的作用方式刺激增殖有关。另一方面，基因表达水平测试发现，E2和 BPA在影响增殖有关的不同基因表达上有不同的作用强度和偏好，这也说明了细胞水平上联合毒性研究的复杂性。将反映整体效应的测试终点细化到特定的一个或数个作用方式上是一种深入研究的思路，基于此进行实验设计、模型建立和效应预测也是未来的发展方向之一。 |
| 英文摘要 | Endocrine disrupting chemicals (EDCs) are a class of exogenous compounds that can interfere with the endocrine (or hormone) system in mammals at certain dose, and their reproductive and developmental toxicities after the long-term exposure to environmental observed concentrations aggravate the worries about the impacts on human health. A variety of EDCs are emitted from different sources and seldem exist individually in any environmental compartment, leading to the combined adverse effects on organisms. In this study, the combined effects of the estrogen receptor (ER) disrutping chemicals - which are of the of special concern among EDCs - on different biological levels are assessed by using two high-throughput in vitro bioassays, as well as the predictive abilities of two classic model in mixture toxicity research:concentration addition (CA) and response addition (RA). Receptor-binding is one of the most important modes of action (MoA) of ER disrupting chemicals. For the combined effects of estrogens and estrogenic compounds,31 mixtures containing up to 9 estrogenic components were perpared following both the equivalent effect design and randomly mixed principle. Their mixture toxicities were evaluated through the two-hybrid recombinant yeast assay, and the predictive performances of CA and RA were compared. The results showed that for the yeast assay providing only one MoA, CA model and the derived estradiol equivalent approach can discribe the combined effects well, which was independent on the composition, concentration levels and potencies of mixture components. For estrogens and antiestrogens, 3 estrogens and 3 antiestrogens were used to creat 15 mixtures by fixed-ratio design. In the antagonistic activity test when setting the concentration of model estrogen to its sub-maximal effect concentration, it was found that the the effects of antiestrogenic mixtures can be predicted by the CA model and tamoxifen equivalent concept. If the estrogens and antiestrogens coexist, the presence of antiestrogens decreases the response to estrogen, causing misestimation of the estrogen quantity. On the level of cell proliferation, ER disrupting chemicals can induce proliferation of the human breast cancer cell MCF-7 cell via multiple MoAs, leading to the different outcome of combined effects from the previous receptor-binding activity. Therefore, the joint toxicity of estrogenic mixtures were assessed by using MCF-7 cell, which was sensitive to the exposure of estrogens. According to the results, the mixture containing equal-effective doses of 17β-estradiol and Bisphenol A showed a antagonistic manner on MCF-7 proliferation, and this is due to the different pathways through which 17β- estradiol and Bisphenol A act on the cell. On the other hand, the gene expression test found that 17β-estradiol and Bisphenol A showed distinct patterns on the expression of key gene related to cell proliferation. This suggests the complexity of mixture research on cell level. Hereby, separating the endpoint of 'whole effect' into one or several MoAs gives us a possible hint for further research, and it will be a research direction to conduct experimental design and effect prediction accordingly in the future. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34457]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 杨蓉. 相同和不同作用机制雌激素系统干扰物的联合毒性[D]. 北京. 中国科学院研究生院. 2015. |
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