Effects of bisphenol A exposure on DNA integrity and protamination of mouse spermatozoa
Effects of bisphenol A exposure on DNA integrity and protamination of mouse spermatozoa
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双酚 A 暴露对小鼠精子 DNA 完整性和延长的影响
DOI：
10.1111/andr.12694
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发表时间：
2019-09-05
期刊：
影响因子：
4.5
通讯作者：
Xie, M.
中科院分区：
文献类型：
--
作者：
Pan, D.;Feng, D.;Xie, M.
背景双酚A广泛用于聚碳酸酯塑料的制造，其对精子发生的潜在不利影响已引起越来越多的关注。然而，双酚A对精子发生的影响尚不清楚。目的探讨双酚A是否对生精细胞DNA完整性和变性有不良影响。材料与方法新生雄性小鼠从出生后第1天至35天每天皮下注射双酚A(0.1，5 mg/kg体重，n=15)或硬币油(对照组，n=20)。在出生后第70天，采集附睾尾精子和睾丸。分析精子数、精子活动率和精子形态。精子染色质结构分析检测精子DNA片段化。用末端脱氧核苷酸转移酶dUTP缺口末端标记法(TUNEL)检测生精细胞的凋亡。在透射电子显微镜下观察睾丸切片的超微结构特征。用Western印迹和RT-PCR方法检测小鼠睾丸组织中过渡蛋白(TNP)1和Tnp2、鱼精蛋白(Prm)1和Prm2蛋白及其mRNA的表达水平。结果双酚A可显著降低精子数，降低精子活力，增加精子畸形率。暴露于双酚A的小鼠精子染色质完整性差，TUNEL阳性生精细胞增多。睾丸超微结构分析显示，暴露于双酚A可导致染色质不完全凝聚、残留细胞质滞留和顶体异常形成。此外，双酚A组小鼠睾丸组织中Tnp2和Prm2的相对表达水平显著降低。讨论与结论新生鼠暴露于双酚A可能对成年小鼠的精子质量产生负面影响。从机理上讲，我们发现双酚A降低了精子染色质的完整性，同时增加了DNA损伤，这可能是由于精子的污染不良所致。
Background Bisphenol A is widely used in the manufacture of polycarbonate plastics and has caused increasing concern over its potential adverse impacts on spermatogenesis. However, the effect of bisphenol A on spermiogenesis is yet to be explored. Objectives To evaluate whether bisphenol A has adverse effects on DNA integrity and protamination of spermatogenic cell. Materials and methods Newborn male mice were subcutaneously injected with bisphenol A (0.1, 5 mg/kg body weight, n = 15) or coin oil (control group, n = 20) daily from post-natal day 1 until 35. At post-natal day 70, epididymis caudal spermatozoa and testes were collected. Sperm count, sperm motility, and sperm morphology were analyzed. The sperm chromatin structure assay was performed to examine the sperm DNA fragmentation. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method was used to assess apoptosis of spermatogenic cells. The ultrastructural features of testicular sections were examined under a transmission electron microscope. Western blot and RT-PCR were used to detect the expression levels of transition protein (Tnp) 1 and Tnp2, protamine (Prm) 1 and Prm2 protein, and mRNA in mice testes. Results Bisphenol A significantly reduced sperm counts, impaired sperm motility, and increased the percentage of malformed spermatozoa. Poor sperm chromatin integrity and increased TUNEL-positive spermatogenic cells were also observed in mice exposed to bisphenol A. Ultrastructural analysis of testes showed that bisphenol A exposure caused incomplete chromatin condensation, retention of residual cytoplasm, and abnormal acrosome formation. In addition, the relative expression levels of Tnp2 and Prm2 in mice testes decreased significantly in bisphenol A groups. Discussion and conclusion Our findings identified that neonatal bisphenol A exposure may negatively contribute to the sperm quality in adult mice. Mechanistically, we showed that bisphenol A reduced sperm chromatin integrity along with increased DNA damage, which may be due to poor protamination of spermatozoa.