不同胎龄大鼠的组织铅分布

为研究不同胎龄胚胎／胎儿的组织铅分布规律，本研究用大鼠作动物模型，观察了４种染毒剂量下不同胎龄大鼠组织中的铅分布。将断乳２周的雌性Ｗｉｓｔａｒ大鼠１２０只，随机分为４组，分别饮含Ｐｂ２＋浓度为０、１０、５０和２００ｍｇ／Ｌ的饮水，１０周后与正常雄鼠交配，将各组孕鼠再随机分为４个亚组，于妊娠第１０、１４、１７、２０天时处死，测孕、胎鼠组织的铅含量。结果胎鼠脑铅含量随胎龄增长而增加，但脑铅浓度保持不变；胎鼠体铅含量随胎龄增长呈增加趋势，但胎龄１０天大鼠的体铅浓度高于１４天者。胎鼠体铅含量于妊娠后期较前期明显增加；胎鼠铅含量随胎龄的增加可能与妊娠后期胎鼠体内不断出现新的铅结合位点，特别是骨骼钙化有关。

Distribution of lead in fetal rat tissue at different days of pregnancy

In order to reveal the mechanism of the transplacental transfer of lead from mothers to fetus, tissues lead content of fetal rat at different days of pregnancy were determined and compared. Lead was administered to four groups of 4 week old female Wistar rats for 50 days. The doses of lead were 0,10,50 and 200 mg/L in drinking water respectively. Rats were mated with non lead treated male rats. The pregnant rats in each group were then divided into four sub groups by random. The pregnant rats in four sub group of each group were sacrificed in turn at 10,14,17 and 20 days of gestation (dg). Blood lead of pregnant rats, lead burden of whole fetus, lead conentration of fetal brain, fetal liver and placenta were determined. Results indicated that lead concentration in fetal brain kept unchanged during the period of gestation, but lead content in whole fetus and fetal brain were increased with the days of gestation. But the lead concentration in fetus at 10 dg was higher than that at 14dg. It seemed that higher lead absorption by the fetus was related to the newly emerged lead bonding site in fetus, especially during the calcification of bones.