妊娠不同时期铅暴露对大鼠胎盘细胞凋亡的影响

目的 观察妊娠不同时期铅暴露对大鼠胎盘细胞凋亡的影响。方法 研究共分为4组，每组27只Wistar大鼠，雌性18只，雄性9只。雌雄2:1合笼，以发现雌鼠阴栓次日为妊娠第0天。妊娠期全程铅暴露组大鼠妊娠期全程（妊娠1～20 d）饮服o.025％醋酸铅溶液染毒，妊娠甲.期铅暴露组大鼠妊娠早期（妊娠1～10 d）饮服0.025％醋酸铅溶液染毒，妊娠晚期铅暴露组大鼠妊娠晚期（妊娠11～20 d）饮服0.025％醋酸铅溶液染毒，对照组大鼠妊娠期全程饮服蒸馏水。原子吸收光谱法测定妊娠末期（妊娠19～21 d）血铅水平；Hoechst染色法和脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术检测胎盘细胞凋亡并计算凋亡指数。各组间比较采用单因素方差分析，两两比较采用q检验。 结果妊娠末期血铅水平在妊娠期全程铅暴露组(1.74±0.19) μmol/L]、妊娠早期铅暴露组（1.27±0.26） μmol/L.]、妊娠晚期铅暴露组（0.60±0.11）μmol/L]和对照组(0.04±0.01) μmol/L]依次降低，差异均有统计学意义（F=12.10，P＜0.01）。Hoechst染色法显示，铅暴露组胎盘滋养层凋亡细胞核浓染，部分核内可见致密块状荧光颗粒，对照组凋亡细胞呈散在分布。脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术检测显示，铅暴露组大鼠胎盘滋养层凋亡细胞核呈棕黄色，部分核中有棕黄色颗粒。凋亡细胞核较正常增大，呈椭圆形或不规则形，核内染色质聚集于边缘处。2种凋亡检测方法均显示各铅暴露组胎舷细胞凋亡指数均高于对照组，且妊娠期全程铅暴露组高于妊娠早期和妊娠晚期铅暴露组（P均＜0.05）。 结论 妊娠期铅暴露大鼠血铅水平升高，促进胎盘细胞凋亡的发生。

Lead exposure during different periods of pregnancy in placental apoptosis in rats

Objective To investigate the effects of lead exposure on rat placental apoptosis during different periods of pregnancy. Methods All Wistar rats were randomly divided into four groups with 27 for each group with the sex ratio of 2 : 1 (female : male). The groups with lead exposure consumed water with 0. 025％ lead acetate during the entire, early or late period of pregnancy. Controls were given distilled water without lead. Blood lead levels were determined by atomic absorption spectrophotometry at the end of pregnancy. Placental apoptosis were assessed by both Hoechst staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay. Data were assessed by one-way analysis of variance, and differences between groups were compared by q-test. Results Blood lead levels at the end of pregnancy of the groups with lead exposure (entire, early or late pregnancy) and the control group were (1. 74±0. 19) μmol/L,(1.27±0.26) μmol/L, (0.60±0. 11) μmol/L and (0.04±0.01) μmol/L respectively(F= 12. 10,P＜0.01). In the groups with lead exposure, Hoechst staining showed hyperchromatic nuclei in placental trophoblast apoptotic cells and compact fluorescent particles in some nucleus； TUNEL assay showed brown-staining apoptotic cells nuclei with some nuclei particles staining brown. Two assays showed the same results: the apoptotic index of the groups with lead exposure were higher than that of the control group; the apoptosis index of the group with lead exposure during entire pregnancy was higher than that of the group with lead exposure during early and late pregnancy (P ＜ 0. 05).Conclusions Lead exposure during pregnancy could elevate the blood levels of lead and the degree of placental apoptosis.