Effects of 2,3,7,8-TeCDD during pregnancy on the neurodevelopment of rat fetuses and off-springs

本实验观察了妊娠期9 ~ 19天的孕鼠经口给予2，3，7，8-TeCDD（TeCDD）或玉米油对仔鼠运动发育和学习过程的影响<th><th>。暴露组和对照组仔鼠出生后可自由采食母乳，断奶后可自由采食食物和水。进行了以下实验并获得了实验结果. TeCDD对胎仔脑的影响：妊娠第19天，将6只TeCDD组胎仔和5只对照组胎仔从子宫内取出。从胎儿中收集脑，并分为三个部分：大脑、小脑和下丘脑。TeCDD组下丘脑/全脑比率显著高于对照组. TeCDD对仔鼠的影响：仔鼠出生后4 <th>~ 14天<th>，测量在斜坡上转身的时间，检测运动发育。在7 ~ 11天内，TeCDD组的潜伏期显著长于对照<th><th>组。出生后31 <th>~ 44天<th>，每天在穿梭箱中用音调和电击条件化后检查回避行为的表现。与对照组相比，TeCDD组大鼠逃避率和逃避潜伏期的改善延迟。在TeCDD暴露的雄性大鼠中也观察到较低的自发活动。在行为学检查后的解剖学研究中，TeCDD组大鼠下丘脑/全脑的比率也有所增加，提示妊娠期暴露TeCDD会影响子代生长期的神经发育，尤其是雄性大鼠。

The effects of 2,3,7,8-TeCDD (TeCDD) during pregnancy on motor development and learning processes of rat off-springs were investigated in this study.TeCDD or corn oil was orally administered to pregnant rats during the 9^<th> - 19^<th> day of pregnancy. Both of exposed and control off-springs were fed with ad libitum access to maternal breast milk after birth, and to food and water after weaning. The following experiments were conducted and obtained the results.1. Effects of TeCDD on fetus brain : On day 19 of gestation, fetuses of 6 TeCDD group and 5 controls were removed from the uterus. Brains were collected from the fetuses and divided into three parts : the cerebrum, cerebellum, and hypothalamus. The rates of hypothalamus per whole brain of TeCDD group were significantly higher than those of controls.2. Effects of TeCDD on off-springs : From the 4^<th> to 14^<th> day after birth, measurement the time of turning around on the slope was performed to test motor development. The latent time of TeCDD group was significantly longer than that of controls during the 7^<th> to 11^<th> day in both sexes. Every day from the 31^<th> to 44^<th> day after birth, performance of avoidance behavior in a shuttle box was examined after conditioning with a tone and electric shock. Improvement of escape rates and escape latent periods during these days was delayed in TeCDD group as compared with that of controls in male rats. Also lower spontaneous activity was observed in TeCDD exposed male rats. The increased rates of hypothalamus per whole brain of TeCDD group were also recognized in anatomical investigations after behavior examinations.These results suggest that TeCDD exposure during pregnancy affect neurodevelopment of off-springs during growth period, especially in male rats.