School of Biological Sciences, Campus Box 4120, Illinois State University, Normal, IL 61790-4120, USA.
Gen Comp Endocrinol. 2010 Apr 1;166(2):217-21. doi: 10.1016/j.ygcen.2009.11.011. Epub 2009 Nov 20.
During development, embryos utilize steroid signals to direct sexual differentiation of tissues necessary for reproduction. Disruption of these signals by exogenous substances (both natural and synthetic) frequently produce phenotypic effects that can persist into adulthood and influence reproduction. This paper reviews the evidence that during embryonic development, progesterone metabolites and xenobiotic-sensing nuclear receptors may interact to increase the expression of numerous enzymes responsible for steroid metabolism in oviparous and placental amniotes. In these groups, embryonic development is characterized by (1) elevated progesterone concentrations, (2) 5 beta reduction being the primary metabolic pathway of progesterone, (3) the presence of xenobiotic-sensing nuclear receptors that can bind 5 beta metabolites of progesterone, and (4) increased expression of a suite of enzymes responsible for the metabolism of multiple steroids. We propose that xenobiotic-sensing nuclear receptors initially evolved to buffer the developing embryo from the potentially adverse effects of various maternal steroids on sexual differentiation.
在胚胎发育过程中，胚胎利用类固醇信号来指导生殖所必需的组织的性别分化。外源性物质（天然和合成）对这些信号的干扰经常产生表型效应，这些效应可以持续到成年期并影响生殖。本文综述了以下证据：在胚胎发育过程中，孕激素代谢物和外源物质感应核受体可能相互作用，增加许多负责卵生动物和胎盘羊膜动物类固醇代谢的酶的表达。在这些动物中，胚胎发育的特征是：（1）孕激素浓度升高；（2）5β还原是孕激素的主要代谢途径；（3）存在可以结合孕激素 5β代谢物的外源物质感应核受体；（4）负责多种类固醇代谢的一系列酶的表达增加。我们提出，外源物质感应核受体最初的进化是为了缓冲发育中的胚胎免受各种母体类固醇对性别分化的潜在不利影响。
