微量镉对胎鼠睾丸超微结构及P450scc表达的影响

Effect of Maternal Exposure to Trace Cadmium on Ultrastructure and P450scc Expression in Fetal Testicles

目的研究孕期微量镉暴露对胎鼠睾丸超微结构的损伤及细胞色素P450胆固醇侧链裂解酶(P450scc)表达的影响,探讨镉对雄性子代生殖发育的干扰作用。方法成熟雌性SD大鼠12只,随机分为2个镉染毒组[1.2、1.5 mg/(kg·d)]和对照组,于孕期第9、11、13天腹腔注射氯化镉,对照组给予等体积生理盐水。妊娠第18天行剖宫产取雄性胎鼠睾丸作光镜、电镜观察及P450scc免疫组化分析。结果光镜下1.5 mg/(kg·d)镉染毒组睾丸精曲小管内支持细胞排列紊乱,间质异常增生,1.2mg/(kg·d)镉染毒组无明显改变。电镜下两个镉染毒组均见支持细胞、精原细胞及间质细胞内线粒体肿胀、内质网扩张,间质细胞内脂滴堆积,尤以支持细胞和间质细胞损伤最为明显。镉染毒组间质细胞中P450scc阳性产物表达均显著低于对照组(P<0.01)。结论孕期微量镉暴露可致性分化期胎鼠睾丸超微结构损伤,降低睾酮合成关键酶的活力。

Objective To investigate the effects of maternal exposure to trace cadmium （Cd） on fetal testicles uhrastructure and cholesterol side-chain cleavage enzyme P450 （P450scc）. Methods Twelve pregnant SD rats were randomly divided into the control group and two CdCl, treated groups. On the 9th, 11th, 13th day during the pregnant period respectively, through intraperitoneal injection, the control group was treated with equivalent normal saline, the other two groups were treated with 1.2, 1.5 mg/（kg.d） CdCl2. On the 18th day during the pregnant, cesarean section was conducted to get fetus, the testes were collected for immunohistochemistry of P450scc, light microscope and ultrastructure examination. Results Sertoli＇ s cells arranged disorder in 1.5 mg/（kg, d） CdCl2 group, whereas 1.2 mg/（kg, d） CdCl2 group had no obvious changes compared with the control group. Abnormal ultrastrueture changes of contorted seminiferous tubules and Leydig cells were also observed in two CdCl2 groups. Swollen mitochondria and expanded endoplasmic reticulum were seen in Sertoli＇ s cells, gonocyte and Leydig cells. Moreover, lipid droplets were cumulated in Leydig cells. The positive products of P450scc significantly decreased in CdCl2 groups compared with the control group （P〈0.01）. Conclusion During the critical period of male sexual differentiation, exposure to trace cadmium （Cd） may lead a significant ultrastrueture damage in fetal testes, and can reduce the activity of key enzyme of testosterone synthesis.