镉暴露小鼠生精细胞DNA损伤与Bcl-2和Bax表达率及超微结构改变

目的研究镉暴露对小鼠睾丸生精细胞DNA的损伤作用、bcl-2和Bax蛋白表达率及超微结构的变化。方法取24只雄性ICR小鼠随机分为4组，每组6只，分别以1、5、10μmol／kg氯化镉腹腔注射，每天1次，连续5d，设阴性对照生理盐水组。于第6天用单细胞凝胶电泳（single-cell gel electrophoresis，SCGE）技术检测生精细胞DNA损伤情况，免疫组化法测定生精细胞Bcl-2和Bax蛋白表达阳性率，透射电镜观察生精细胞超微结构变化。结果腹腔注射1、5、10μmol／kg氯化镉组小鼠睾丸生精细胞DNA损伤率（分别为35．00％、61．25％、82．50％）明显高于对照组（14．75％），差异有统计学意义（P〈0．01），Bcl-2蛋白表达阳性细胞率明显低于对照组，差异有统计学意义（P〈0．01），5μmol/kg组Bax蛋白表达细胞阳性率明显高于对照组和1、10μmol／kg组。透射电镜观察显示，3种剂量处理组生精细胞核染色质、核膜、线粒体和内质网超微结构发生不同程度的病理改变，并随着处理浓度的升高，超微结构改变程度加重。结论小鼠镉暴露可导致生精细胞DNA断裂，Bcl-2和Bax蛋白表达率发生变化，细胞超微结构发生病理性改变。

DNA damage, Bcl-2 、Bax expression and ultrastructure change in spermatogenic cell of mice exposed to cadmium

OBJECTIVE: To study DNA damage, Bcl-2 and Bax expression, and ultrastructure change in spermatogenic cell of mice by cadmium exposure. METHODS: Twenty-four male mice were divided into 4 groups: 3 groups treated with cadmium chloride of 1, 5, 10 micromol x kg(-1) x d(-1) i.p. respectively for 5 days, and one normal saline control group. The DNA damage of spermatogenic cell by single-cell gel electrophoresis technology was detected. The expression positive rate of Bcl-2, Bax protein in spermatogenic cell by the immunohistochemical method was assayed, and the ultrastructural change of spermatogenic cell by the transmission electron microscope was observed. RESULTS: DNA damage rates of of spermatogenic cell in 1, 5, 10 micromol/kg cadmium chloride groups were higher than that of normal group (P < 0.001). Bcl-2 protein expression positive rates were lower than that of normal group (P < 0.001). Bax protein positive expression rate in 5 micromol/kg group was higher than those in normal group, and 1, 10 micromol/kg groups. The ultrastructure of karyotin, karyotheca, mitochondria, endoplasmic reticulum in three treated groups had different degree of damage and the degree of ultrastructural change was increasing with rising concentration of cadmium. CONCLUSION: Cadmium exposure will cause the DNA break, Bcl-2 and Bax protein abnormal expression and ultrastructural change in spermatogenic cell.