妊娠期低水平铅暴露时胎盘组织中金属硫蛋白的表达

Expression and significance of metallothionein in the placenta of women with low level lead exposure during pregnancy

目的 探讨孕期低水平铅暴露时胎盘组织中金属硫蛋白的定位与表达.方法从青岛市立医院2005年3月到2006年3月住院分娩的孕妇中随机选择血铅水平在1.5～4.8 μmol/L之间的孕妇67例,其中35例血铅水平低于2.9 μmol/L（A组）,32例血铅水平高于2.9 μmol/L（B组）.应用免疫组化链霉菌抗生物素蛋白-过氧化物酶连接法检测两组胎盘组织中金属硫蛋白的定位与表达.结果 （1）67例孕妇中血铅水平最高为4.7 μmol/L,最低为1.6 μmol/L.其中,A组孕妇血铅水平平均为（1.7±0.3） μmol/L;B组孕妇血铅水平平均为（3.1±0.4） μmol/L,两组比较,差异有统计学意义（P＜0.05）.（2）金属硫蛋白主要表达于细胞质中,在胎盘组织中的蜕膜细胞、滋养细胞及血管内皮细胞呈弥漫性或散在分布.（3）A、B组金属硫蛋白在胎盘组织中的阳性表达率分别为74%（26/35）和91%（29/32）,两组比较,差异有统计学意义（P＜0.05）.（4）母体血铅水平与胎盘组织中金属硫蛋白的表达强度呈剂量-效应关系.结论血中低水平铅可诱导胎盘组织中金属硫蛋白的表达,并呈剂量-效应关系.金属硫蛋白主要定位于胎盘组织中的蜕膜细胞、滋养细胞及血管内皮细胞,提示对胎盘组织结构的完整性和功能发挥具有重要作用.

Objective To investigate the significance of metallothionein （MT） expression in the placenta of women exposed to low level lead during pregnancy. Methods Sixty-seven pregnant women with blood lead level ranging from 1.5 μmol/L to 4. 8 χμmol/L were randomly selected from the Department of Obstetrics of Qingdao Municipal Hospital between Mar 2005 and Mar 2006. Among them, 35 were with blood lead level less than 2.9 χμmol/L （group A） and 32 more than 2.9 χμmol/L （group B）. Immunohistochemical streptavidin-peroxidase-biotin methods were used to observe the expression of MT in the placental tissue. Results （ 1 ） Among the 67 pregnant women, the highest level of blood lead was 4. 7 μmol/L , and the lowest level was 1.6 χμmol/L . The blood lead level of groups A and B was （ 1.7 ± 0. 3 ） μmol/L, and （ 3.1 ± 0.4 ） μmol/L, with a significant difference between them （ P 〈 0.05 ） . （ 2 ） The positive expression of MT was mainly cytoplastic in the cytotrophoblast, decidual cell and small vascular endothelial cells. The positive cell staining was diffuse or scattered. （3） The positive staining of MT was 91% （29/32） and 74% （26/35） in the placental tissue of groups A and B, respectively, with a significant difference between them（ P 〈 0.05 ）. （4） The blood lead level of pregnant women was correlated with the expression of MT of placenta. Conclusions Lead can induce the expression of MT in the placental tissue in a dose-dependent manner. MT is mainly located in the cytotrophoblast, decidual cell and small vascular endothelial cells of the placenta. MT expression in the placenta is important to the structural integrity and function of the placenta.