Characterizing the effect of bisphenol-A on the metabolism of maternally derived

描述（由申请人提供）：所有脊椎动物胚胎都是在母体衍生的类固醇存在下发育的，越来越多的证据表明这些类固醇受胚胎代谢的影响。这种代谢通常被认为是调节胚胎暴露于母体类固醇的“缓冲”。最近的研究表明，母源性雌二醇在发育早期转化为雌酮硫酸盐，而内分泌干扰化学物质双酚a抑制这种转化，这促使人们进一步研究双酚a是如何破坏类固醇代谢的，以及这种破坏的长期后果。本研究利用野生海龟模型，为评估母体类固醇、内分泌干扰和代谢之间的相互作用提供了一个很好的系统，因为：(1)类固醇和类固醇原酶在脊椎动物中是保守的；(2)海龟胚胎非常适合实验操作；(3)海龟的性别决定对类固醇和内分泌干扰化学物质敏感，这为评估内分泌干扰提供了一个诊断工具。该提案的第一个目的是确定双酚a是否是一种普遍存在的类固醇磺化抑制剂。这一目标将描述孕酮、睾酮和皮质酮在早期发育过程中的代谢命运，并验证BPA广泛抑制胚胎类固醇代谢的假设。为了实现这一目标，外源性类固醇和双酚a操作将用于确定早期发育过程中的代谢物形成。该提案的第二个目的是确定双酚a对母体衍生雌二醇的卵内代谢的抑制作用。这一目的将检验正常胚胎类固醇代谢的抑制对由此产生的幼仔具有表型后果的假设。为了实现这一目标，还将采用外源操作来评估这些操作对后代性别的影响。这项工作的结果将为内分泌干扰提供重要的新信息，这些信息可能超出了双酚a的影响，并揭示了内分泌干扰物活性的非受体介导途径的潜在机制。

DESCRIPTION (provided by applicant): All vertebrate embryos develop in the presence of maternally derived steroids and accumulating evidence suggests that these steroids are subject to prolific embryonic metabolism. This metabolism is frequently thought of as a "buffer" that regulates embryonic exposure to maternal steroids. The recent demonstration that maternally derived estradiol is converted to estrone sulfate early in development and that the endocrine disrupting chemical bisphenol-A inhibits this conversion has prompted further investigation to understand how bisphenol-A disrupts steroid metabolism and the long-term consequences of this disruption. The proposed research utilizes a wild turtle model that provides an excellent system for evaluating the interaction between maternal steroids, endocrine disruption, and metabolism because: (1) steroids and steroidogenic enzymes are conserved across vertebrates, (2) turtle embryos are very amenable to experimental manipulation, and (3) sex determination in turtles is sensitive to steroids and endocrine disrupting chemicals which provides a diagnostic tool for assessing endocrine disruption. The first aim of the proposal will determine if bisphenol-A is a ubiquitous inhibitor of steroid sulfonation. This aim will characterie the metabolic fate of progesterone, testosterone, and corticosterone during early development and test the hypothesis that BPA is broadly capable of inhibiting embryonic metabolism of steroids. To accomplish this aim, exogenous steroid and bisphenol-A manipulations will be used to determine metabolite formation during early development. The second aim of the proposal will determine the inhibiting effects of bisphenol-A on the in ovo metabolism of maternally derived estradiol. This aim will test the hypothesis that inhibition of normal embryonic steroid metabolism has phenotypic consequences for the resulting hatchling. To accomplish this aim, exogenous manipulations will also be employed to assess the effects of these manipulations on offspring sex. The results from this work will provide important new information on endocrine disruption that may extend beyond the effects of bisphenol-A, and shed light on an underlying mechanism for non-receptor mediated pathways for endocrine disruptor activity.