镉、汞、锌3种重金属的雌激素样作用

Estrogenic Activity of Cadmium, Mercury,and Zinc

为探讨镉、汞、锌3种重金属的雌激素样作用,采用双杂交酵母法测定了醋酸镉、氯化汞、醋酸锌单独作用时对重组基因酵母β-半乳糖苷酶诱导活性的EC50值.实验结果表明,醋酸镉浓度为1.0×10-5mol·L-（1实验浓度范围10-7~10-2mol·L-1）,氯化汞浓度为5.0×10-7mol·L-（1实验浓度范围10-9~10-5mol·L-1）,醋酸锌浓度为1.0×10-4mol·L-（1实验浓度范围10-9~10-2mol·L-1）时对酵母β-半乳糖苷酶诱导活性最大,分别达到1.3、0.95和1.1U.不能求出镉、汞、锌单独作用时对β-半乳糖苷酶诱导活性的EC50值.一味计算EC50值不仅难以评价重金属的雌激素活性,而且限制重组受体基因酵母法的普遍运用.一些重金属通过MCF-7细胞法（E-screen）呈阳性,通过重组hERα酵母法YES检测呈阴性,有可能是重金属通过与ERβ作用而产生效应.若构建出含ERβ基因的双杂交酵母菌株,与现有的方法互补将能完善环境雌激素的体外测评系统.

In order to explore the estrogenic activity of cadmium, mercury, and zinc, the activity of β-galactosidase of the recombinant human estrogen receptor -α （hERα）gene yeast induced by mercuric chloride, cadmium acetate, and zinc acetate was determined. Results show that the activity of β -galactosidase of this yeast reaches the maximum at the concentration of 5.0×10-7mol·L-1 for mercuric chloride （concentration range： 10 -9~10 -5mol·L -1）, 1.0 ×10 -5mol·L -1 for cadmium acetate（concentration range： 10-7~10-2mol·L-1）and 1.0×10-4mol·L-1 for zinc acetate （concentration range： 10-9~ 10-2mol·L-1）, and the activities are 0.95, 1.3, and 1.1U, respectively. EC50 values of single cadmium, mercury, and zinc to β-galactosidase cannot be calculated. If we estimate the estrogenic activity of the heavy metal just by the EC50 value, then it’s hard to estimate the estrogenic activity of the heavy metal and the wide use of the recombinant yeast estrogen screen will be impeded. Some heavy metals show positive by E -screen, but negative by YES, likely because they bind to the ERβ. So the environmental estrogens assay in vitro will be improving if the recombinant human estrogen receptor -β （hERβ）gene yeast could be constructed.