AhR- and ER-Regulated Genes in Brain Development

描述(由申请人提供)：我们的长期目标是确定发育过程中暴露于二恶英和其他普遍存在的芳烃受体(AhR)配体改变成年后生殖功能的机制。我们最近发现，发育过程中暴露于强大的AhR配体2，3，7，8-四氯二苯并-对二恶英(TCDD)，干扰了雌激素依赖性的男性前腹侧脑室周围核(AVPV)的性别分化。AVPV控制着雌性黄体生成素(LH)的释放模式；因此，暴露于TCDD的雄性动物具有类似雌性的AVPV结构，他们在成年期表现出雌性的黄体生成素释放周期模式。考虑到胎儿产生睾酮所产生的雌二醇(E2)负责性别分化过程，我们假设TCDD干扰了发育过程中一组基因的E2调节。为了验证这一假设，我们将使用Affymetrix微阵列和聚类分析来识别受E2和TCDD调控的性别特异基因。我们将使用“冗余模型”，测试我们的假设所预测的不同动物治疗方法，以针对同一组基因。我们将使用RT-QPCR、原位杂交组织化学、发育个体发育研究、剂量反应研究和启动子分析来验证我们的微阵列结果。我们的发现对于确定二恶英和其他普遍存在的AhR配体对生殖毒性的潜在影响，以及对围产期TCDD暴露以性别特异性方式破坏的其他神经功能的潜在影响将是重要的。这些发现将对基于机制的风险评估以及预防神经毒性的药物干预措施的开发具有重要意义。

DESCRIPTION (provided by applicant): Our long-term objective is to determine the mechanisms by which developmental exposure to dioxins and other ubiquitous arylhydrocarbon receptor (AhR) ligands alters reproductive functions in adulthood. We recently showed that a single developmental exposure to the potent AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), interferes with estrogen-dependent sexual differentiation of the male anteroventral periventricular nucleus (AVPV). The AVPV controls the female pattern of luteinizing hormone (LH) release; therefore, TCDD-exposed males have a female-like AVPV structure and they show the female, cyclic pattern of LH release in adulthood. Considering that estradiol (E2) derived from fetal production of testosterone is responsible for the sexual differentiation process, we hypothesize that TCDD interferes with E2 regulation of a set of genes during development. To test this hypothesis, we will use Affymetrix microarrays and cluster analysis to identify sex-specific genes that are regulated by E2 and TCDD. We will use a "redundancy model", testing different animal treatments predicted by our hypothesis to target the same set of genes. We will validate our microarray findings using RT-QPCR, in situ hybridization histochemistry, developmental ontogeny studies, dose response studies and promoter analysis. Our findings will be important for identifying genes underlying effects of dioxins and other ubiquitous AhR ligands on reproductive toxicity, as well as on other neural functions disrupted by perinatal TCDD exposure in a sex-specific manner. Such findings will be important for mechanism-based risk assessment, as well as for development of pharmaceutical interventions to prevent neurotoxicity.