亚硝酸盐暴露致雄性小鼠生殖毒性的探讨

目的 探讨亚硝酸盐暴露对雄性小鼠生殖毒性的分子机制。 方法 36只2月龄健康雄性小鼠，随机分为对照组(生理盐水）、低剂量组（60 mg/kg）和高剂量组（120 mg/kg），每组12只进行亚硝酸盐灌胃3个月，观察小鼠的生长状况，HE染色法观察睾丸组织病理变化，免疫荧光和Western blotting方法分析检测睾丸组织细胞增殖与凋亡情况及DNA甲基化、组蛋白去乙酰化相关酶的表达情况。 结果 亚硝酸盐暴露组小鼠较对照组小鼠体重增加缓慢，睾丸指数降低（P<0.01），形态发生病理性改变；亚硝酸盐暴露组小鼠睾丸组织细胞增殖较对照组明显减少，细胞凋亡较对照组明显增加（P<0.01）；同时DNA甲基化和组蛋白去乙酰化水平高于对照组（P<0.01），且均具有剂量依赖性。 结论 亚硝酸盐暴露通过抑制雄性小鼠生长发育及睾丸生精细胞增殖，诱导睾丸生精细胞凋亡，造成雄性生殖毒性；DNA甲基化及组蛋白去乙酰化水平升高，提示表观遗传学可能参与了亚硝酸盐暴露对雄性生殖系统的损伤过程及调控机制。

Reproduction toxicity in male mice after nitrite exposure

Objective To investigate the reproduction toxicity and molecular mechanisms in male mice after nitrite exposure.Methods Thirty six healthy 2-month-old male mice were divided into control group,low-dose group (60 mg/kg) and high-dose group (120 mg/kg),12 mice each group.Each mouse was treated with saline or different doses of nitrite by peros once per day for a total of 3 months,and the condition of the mice was monitored every week.The tissue of testis was harvested and the pathological changes of testis were analyzed by HE staining.Immunofluorescence and Western blotting analysis were used to detect the proliferation and apoptosis of testicle cells,DNA methylation and histone deacetylation.Results The body weight of the mice in nitrite treated group increased slowly compared with that in the control group.The coefficients of testicular significant decreased (P ＜ 0.01) and the morphology of testis also changed after nitrite exposure.In addition,the proliferation of testis cells was elevated dramatically while the apoptosis of testis cells reduced markedly compared with vehicle.The enzyme expressions of both DNA methylation and histone deacetylation were increased in a dose dependent manner after nitrite treatment (P ＜ 0.01).Conclusion Nitrite exposure can inhibit mouse growth and spermatogenic cell proliferation,and induce spermatogenic cell apoptosis,leading to reproductive toxicity in male.The increased DNA methylation and histone deacetylation level indicate that epigenetics may be involved in the process of male reproductive system damage and regulatory mechanism by nitrite exposure.