A Model System for the Development of Behavior

9309422哺乳动物生殖行为的性别差异不仅由成年时产生的基因和激素决定，而且还由围产期性腺分泌的类固醇激素决定。虽然已知睾丸雄激素在围产期发育中起重要作用，但雄激素在中枢神经系统靶细胞内被代谢成雌激素。确定一种雄激素或它的雌激素代谢物是否是分化激素是很复杂的，因为胎盘哺乳动物的胎儿实际上有保护他们免受母体雌激素伤害的系统。因此，将雌激素注入胎儿，并量化作用于胎儿的雌激素的数量是极其重要的，但几乎不可能实现。法德姆博士开发了一个有袋类动物模型来研究雌激素的作用。这些新生儿出生的发育阶段相当于13天的胎鼠或8周的人类胚胎。因此，大部分胎儿的发育都发生在母亲的身体之外，这使得这些哺乳动物能够接触到胎儿的环境。法德姆博士将操纵新生有袋类动物的荷尔蒙环境。她将评估这些早期操作对成年后生殖和攻击性行为、形态和生理的影响。这些研究的结果将有助于更好地理解各种人类疾病，这些疾病是由于性分化期间激素暴露不足或过多造成的。***

9309422 Fadem Sex differences in reproductive behavior in mammals are determined not only by the genes and by hormones produced in adulthood, but also by steroid hormones secreted by the gonads during perinatal development. Although it is known that testicular androgens play an important role during perinatal development, androgens are metabolized into estrogens within CNS target cells. Determining whether an androgen or its estrogenic metabolite is the differentiating hormone is complicated since placental mammalian fetuses have systems which actually "protect" them from maternal estrogen. Thus, getting estrogen to the fetus and quantifying the amount of estrogen acting on the fetus is extremely important yet almost impossible to achieve. Dr. Fadem has developed a marsupial model to examine the role of estrogen. The newborns are born at a developmental stage equivalent to that of a 13-day fetal rat or 8-week human embryo. Hence, much of the fetal development occurs outside the body of the mother, making the fetal environment accessible in these mammals. Dr. Fadem will manipulate the hormonal environment of the newborn marsupials. She will assess the effects of these early manipulations on reproductive and aggressive behavior, morphology and physiology in adulthood. The results from these studies will contribute to a better understanding of various human disorders that result from insufficient or excess hormone exposure during sexual differentiation. ***