Developmental Effect of Endocrine Disruptors on Fish and Mice

双酚a （BPA）是一种雌激素化学物质，被给予怀孕的老鼠和日本猴子，并研究了胎盘移植。BPA在小鼠和猴体内分别于30分钟和1小时内进入胎儿的大脑、肝脏和其他器官，表明BPA可以很容易地穿过胎盘。研究人员将双酚a和合成雌激素己烯雌酚（DES）喂给怀孕的老鼠，研究雌性后代的生育能力和各种异常情况。双酚a不能诱导不育、卵巢多卵泡和阴道上皮持续分层。DES在胎儿期下调缪勒管Hoxa-9和a-10基因，提示DES暴露小鼠子宫变化密切相关。为了研究BPA的低剂量问题，在妊娠第10 ~ 17天给予2、20μg/kg体重的BPA和0.02 ~ 2μg/kg的DES。与对照组相比，暴露于20μg双酚a和所有des的雌性后代阴道开口明显提前，体重明显下降。这一结果表明BPA存在低剂量效应，但其机制尚不清楚。新生儿DES治疗导致雌性小鼠尿道下裂，阴道下部尿道腔与阴道腔融合，并观察到细胞凋亡。尿道下裂诱导的关键期为出生后7天。新生儿BPA （150μg）处理的雌性小鼠表现出持续的发情，以及与卵巢无关的阴道变化。为了研究雌性激素对鱼类发育的影响，将异交底泥胚胎暴露于雌二醇中。雌二醇引起各种畸形，包括性别比改变。克隆了雌激素受体α和β，分析了发育过程中雌激素受体ER的表达。FTZ-F1基因也从眼底克隆得到。斑马鱼在孵化后大约20天性腺发育到卵巢，然后一半的鱼从卵巢发育成睾丸。在睾丸形成过程中，卵巢内的卵母细胞发生凋亡。

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.