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目的探讨胎盘对低剂量镉(cadmium,Cd)暴露的屏障作用及相关作用蛋白。方法模拟职业人群的暴露水平,建立连续低剂量Cd(1 mg/kg·bw·d)暴露的大鼠生殖毒性试验模型(44 d),通过石墨炉原子吸收光谱法和DIGE(differential in-gel electrophoresis)荧光标记蛋白质组学方法观察低剂量Cd通透胎盘的比例及可能的作用蛋白。结果与容易透过胎盘的重金属铅(lead,Pb)相比,Cd通过胎盘的比例明显降低。其中染毒44 d母鼠血Cd浓度(16.70±4.77)μg/L,胎鼠脐血Cd浓度(1.40±1.17)μg/L,脐血Cd/母血Cd约为8.38%,与对照组相比差异无统计学意义(P>0.05);母鼠血Pb浓度为(284.95±149.49)μg/L,胎鼠脐血Pb浓度为(165.73±52.17)μg/L,脐血Pb/母血Pb约为58.20%(P<0.05)。蛋白质组学分析发现了13个差异表达的蛋白,根据蛋白的表达模式及生物学功能,筛选出3个差异蛋白进一步分析,分别为内质网应激蛋白Grp94(heat shock protein 90 k Da beta member 1,Grp94)、内质网应激蛋白Grp78(heat shock 70 k Da protein 5,Grp78)和抑制素(prohibitin,PHB)。结论胎盘对低剂量Cd(1 mg/kg·bw·d)暴露有明显的屏障作用,Grp94、Grp78和PHB蛋白可能参与该作用的发挥,具体的转运机制有待深入探讨。
Objective To investigate the barrier function of placenta to cadmium (Cd) exposure and its related proteins. Methods The reproductive toxicity model of rats exposed to continuous low dose Cd (1 mg / kg · bw · d) was established by simulating the exposure of occupational groups. The model was established by graphite furnace atomic absorption spectrometry (DIGE) and differential in-gel electrophoresis) fluorescent labeling proteomics method to observe the proportion of low-dose Cd-permeable placenta and the possible role of protein. As a result, the proportion of Cd that passed through the placenta was significantly lower than that of lead (Pb), which is easily transmitted through the placenta. The concentration of Cd in fetal rat blood was (16.70 ± 4.77) μg / L and the concentration of Cd in fetal rat cord was (1.40 ± 1.17) μg / L and that of cord blood Cd / maternal serum was 8.38% (284.95 ± 149.49) μg / L, Pb concentration in fetal umbilical cord blood was (165.73 ± 52.17) μg / L, umbilical cord blood Pb / maternal blood Pb About 58.20% (P <0.05). Proteomic analysis revealed 13 differentially expressed proteins. Three different proteins were screened for further analysis according to the protein expression patterns and biological functions, namely, the heat shock protein 90 kDa beta member 1, Grp94), Grp78 (heat shock 70 kDa protein 5, Grp78) and prohibitin (PHB). Conclusion The placenta has obvious barrier function to low dose Cd exposure (1 mg / kg · bw · d). The Grp94, Grp78 and PHB proteins may be involved in this effect. The specific transport mechanism remains to be further explored.