MECHANISMS OF TOXICITY OF DIOXIN-LIKE COMPOUNDS TO OVARIAN CELLS

越来越多的证据表明，环境污染物是引起卵巢毒性内分泌紊乱的重要原因。二恶英如TCDD是一种强有力的生殖毒物，已知会影响实验室动物和人类的类固醇水平。这一建议扩展了该小组以前的研究，进入TCDD的作用机制。最近的结果从人类颗粒黄体细胞培养（hGLCC）已经证明，TCDD通过不同的显着的转导途径，诱导特定的酶在hGLCC中表达的翻译后修饰的激素分泌有差异的影响。我们对TCDD对类固醇合成的影响的研究已经显著扩展，并且如何包括TCDD不仅对参与类固醇合成的类固醇底物的利用的影响的研究，而且还包括对17 α羟化酶/17，20-裂解酶复合物的P450和还原酶组分的研究，以及支持雌激素合成的还原当量的可用性。这些研究将确定导致雌激素合成抑制的分子病变，伴随着体内TCDD暴露后胎儿丢失。我们将比较在体外和体内的二恶英对卵巢细胞功能的影响，获得卵巢细胞从猕猴体内处理TCDD在项目II。这些细胞将用于验证体外研究中证实的细胞功能特异性扰动也存在于体内处理动物的细胞中。由于我们的研究结果表明，TCDD也改变了滋养层细胞在体内和体外产生的生物活性和免疫反应性hCG的量，我们将进一步表征如何改变TCDD诱导的hCG亚型影响hGLCC功能。最后，基于TCDD对17，20-裂解酶活性的体外抑制作用，研究将扩展到灵长类动物的卵泡期卵巢细胞。这些联合实验应该产生一个全面的了解机制的行动二恶英对灵长类动物卵巢功能与不孕症和早期胎儿丢失。

Accumulating evidence incriminates environmental pollutants as a significant cause of endocrine disruption involving ovarian toxicity. Dioxins like TCDD are potent reproductive toxicants known to affect steroid levels in laboratory animals and humans. This proposal expands previous studies by this group into mechanisms of action of TCDD. Recent results from human granulosa lutein cell culture (hGLCC) have demonstrated that TCDD has differential effects on hormone secretion through distinct significant transduction pathways that induce -post-translational modifications of specific enzymes expressed in hGLCC. Our studies of the effect of TCDD on steroidogenesis have been significantly expanded and how include studies on TCDD effects on not only utilization of steroid substrates involved in steroid synthesis, but also investigations on P450 and reductase components of 17a hydroxylase /17,20-lyase enzyme complex and the availability of reducing equivalents to support estrogen synthesis. These studies will identify molecular lesions leading to inhibition of estrogen synthesis that accompany fetal loss after in vivo TCDD exposure. We will compare in vitro and in vivo effects of dioxins on ovarian cell function by obtaining ovarian cells from macaques treated in vivo with TCDD in Project II. These cells will be used to validate that the specific perturbations in cellular functions demonstrated in the in vitro studies are also present in cells from in vivo treated animals. Since our results show that TCDD also alters the amounts of bioactive and immunoreactive hCG produced by trophoblasts in vivo and in vitro, we will further characterize how altered isoforms of hCG induced by TCDD affect hGLCC function. Finally, studies will be extended to include follicular phase ovarian cells in primates, based on the TCDD inhibition of 17,20-lyase activity in vitro. These combined experiments should produce a comprehensive understanding of the mechanism of action of dioxin on primate ovarian function associated with infertility and early fetal loss.