Developmental Effect of Endocrine Disruptors on Fish and Mice

双酚A(BPA)是一种雌激素化学物质，给怀孕的小鼠和日本猴进行了经胎盘转运的研究。小鼠胎脑、肝脏等脏器在30min内即可检测到BPA，猴体内1h可检测到BPA，提示BPA很容易通过胎盘进入胎盘。双酚A和合成雌激素己烯雌酚(DES)被给予怀孕的小鼠，并研究了雌性后代的生育能力和各种异常。DES可导致不孕症、卵巢多卵泡形成和阴道上皮持续复层，但不影响BPA。胎儿期DES下调苗勒管Hoxa-9和a-10基因表达，提示DES与子宫变化密切相关。为研究双酚A的低剂量问题，在妊娠第10~17天分别给予2和20μg/kg体重的双酚A和0.02~2μg/kg的双酚A。在20μ、g双酚A和所有DES暴露的雌性后代中，与对照组相比，雌性后代的阴道开放时间明显提前，体重明显减轻。这一结果表明，双酚A存在低剂量效应，但其机制尚不清楚。新生小鼠经DES处理后，阴道下部可见尿路与阴道腔融合，可见细胞凋亡。产后7天为诱导尿路下裂的关键期。为研究雌激素类药物对鱼类发育的影响，将雌二醇暴露于雌鼠胚胎中，观察双酚A(150μg)对雌性小鼠持续发情和卵巢非依赖性阴道改变的影响。雌二醇可引起包括性别比改变在内的各种畸形。克隆雌激素受体α和β，分析雌激素受体在胚胎发育过程中的表达。Fundulus中也克隆了FTZ-F1基因。斑马鱼的性腺在孵化后20天左右发育到卵巢，然后有一半的鱼从卵巢发育出睾丸。在睾丸形成过程中，卵巢内出现卵母细胞的凋亡。

Bisphenol-A (BPA), an estrogenic chemical, was given to pregnant mice and Japanese monkey and studied transplacental transfer. BPA was foun in fetal brain, liver and other organs in 30 min in mice and 1 h in monkey suggesting that BPA can be easily cross the placenta. BPA and a synthetic estrogen, diethylstilbestrol (DES), were given to pregnant mice and studied fertility and various abnormalities in female offspring. DES induced sterility, polyovular follicles in ovary and persistent stratification of vaginal epithelium, but not BPA.Hoxa-9 and a-10 genes in Mullerian duct were downregulated by DES in the fetal period suggesting the close correlation to uterine changes in DES-exposed mice. In order to study low dose issue of BPA, 2 and 20μg/kg body weight of BPA and 0.02-2μg/kg of DES were given to day 10 to 17 of pregnancy. In 20μg BPA-and all DES-exposed female offspring showed significantly early vaginal opening and lower body weight as compared to controls. This results suggest that there is a low dose effect of BPA, however, the mechanism underlie is still unclear. Neonatal DES treatment induced hypospadias in female mice, fusion of urethra and vaginal lumen at lower position of vagina, where apoptosis was observed. The critical period in induction of hypospadias was 7 days after birth. Neonatally BPA (150μg) treated female mice showed persistent estrus, and ovary-independent vaginal changes.In order to study estrogenic agents on development of fish, Fundulus heteroclitus embryos were exposed to estradiol. Various malformations, including sex ratio change were induced by estradiol. Estrogen receptor α and β were cloned and ER expression during development were analysed. FTZ-F1 gene was also cloned from Fundulus. In zebrafish, gonad develops to ovary by ca 20 days after hatching then a half of fish develop testis from the ovary. During testis formation, apoptosis of oocytes occurred in the ovary.