经口镉染毒大鼠前列腺中金属硫蛋白基因表达水平的变化

Effects of oral cadmium exposure on expression of metallothionein-Ⅰ and metallothionein-Ⅱ mRNA in rat prostate

目的 观察经口镉染毒对大鼠前列腺组织中锌、镉含量以及金属硫蛋白 (MT)基因表达水平的影响。方法 4 8只大鼠随机分成 8组 ,每组 6只 ,其中设对照组和 5 0、10 0、2 0 0mg/kg镉染毒组各 2组。大鼠通过饮水给予氯化镉 ,并分别在染毒 1个和 6个月后分批 (每批 4组 )处死大鼠。大鼠前列腺组织中锌、镉含量的测定采用原子吸收光谱法 ,而金属硫蛋白基因 (MT Ⅰ和MT Ⅱ )表达水平的测定采用RT PCR的方法。结果 在镉染毒的第 1个月和第 6个月 ,随着镉染毒剂量的增加 ,锌在大鼠前列腺腹叶中的含量呈逐渐降低的趋势。其中在镉染毒 1个月和 6个月后 ,2 0 0mg/kg镉染毒组大鼠前列腺腹叶中锌的含量分别为 9.5、8.5 μg/g湿重 ,明显低于对照组的 17.0、18.9μg/g湿重 ,差异有显著性 (P <0 .0 5 )。与锌相反 ,各染毒组大鼠前列腺腹叶和背侧叶中镉的含量均明显高于对照组 ,尤以背侧叶增高的幅度更明显。MT Ⅰ和MT Ⅱ在前列腺腹叶的表达水平随着镉染毒剂量的增大而呈逐渐降低趋势 ;在染毒第 1个月和第 6个月 ,2 0 0mg/kg镉染毒组的MT Ⅰ基因相对表达丰度为0 .4 10和 0 .339,MT Ⅱ基因相对表达丰度为 0 .10 0和 0 .112 ,均明显低于对照组MT Ⅰ (0 .76 0 ,0 .830 )和MT Ⅱ (0 .4 2 9,0 .4 39)相对表达丰度 。

Objective To investigate the possible effects of oral cadmium(Cd) exposure on the expression levels of metallothionein-Ⅰ and metallothionein-Ⅱ(MT-Ⅰ and MT-Ⅱ) mRNA and the distribution of zinc(Zn) and Cd in rat prostate. Methods Cadmium was given to rats at doses of 50,100,and 200 mg/kg in drinking water.The contents of Zn and Cd in prostate were measured by atomic absorption spectrometry(AAS),and the levels of MTs mRNA were determined by RT-PCR. Results After Cd administration,the content of Zn was decreased in both the ventral and the dorsolateral lobes of rat prostate.In 200 mg/kg Cd group,the contents of Zn in ventral prostate were 9.5 and 8.5 μg/g wet weight respectively after one month and six months,which were significantly lower than those of control(17.0 and 18.9 μg/g wet weight).In contrast,the contents of Cd in both ventral and dorsolateral lobes of prostate significantly increased with the increasing dose and time of Cd administration.It was also noted that Cd administration resulted in a significant down-regulation of the expression of MT-Ⅰ and MT-Ⅱ mRNA in rat ventral prostate.In 200 mg/kg Cd group after one and six months,the relative expression levels of MT-Ⅰ(0.410,0.339 respectively) and MT-Ⅱ(0.100,0.112 respectively) were significantly lower than those of MT-Ⅰ(0.760,0.830 respectively) and MT-Ⅱ(0.429,0.439 respectively) in control group. Conclusion Oral Cd exposure could influence the distribution of Zn and the expression levels of MTs mRNA in rat prostate.