【作者】 洪蓉；

【导师】 翁恩琪； 刘赟；

【作者基本信息】 华东师范大学 ， 环境生物学， 2004， 硕士

【摘要】 近年来，极低频电磁场(ELF EMFs)是否影响人类生殖健康的问题日益引起关注。流行病学以及实验研究表明ELF EMFs可能与雄性生育能力相关，但有限的实验研究没有得出明确的结论。本工作在雄性小鼠上给予0.2～6.4mT，50Hz2周或4周电磁场间断暴露，采用形态学、生物化学以及细胞学的方法和手段，研究ELF EMFs对雄性小鼠生殖的影响并探讨其可能的作用机制。结果如下： 1．ELF EMFs导致小鼠睾丸重量、体积下降，且暴露4周的效应大于2周。电磁场暴露各组睾丸组织学无明显改变。精子数量、精子活动率下降，精子头部畸形率上升。 2．ELF EMFs暴露导致小鼠睾丸、附睾SOD、GSH—Px酶活下降。附睾组抗·OH能力上升，MDA含量下降，NO含量上升。 3．采用单细胞凝胶电泳检测小鼠睾丸细胞DNA受损程度，显示DNA迁移细胞数和彗尾长度上升。 4．采用流式细胞术检测了睾丸不同倍体细胞的百分比、DNA含量以及各时相的细胞百分比。显示6.4mT电磁场暴露2周组1C细胞百分比显著下降，4周组2C细胞百分比显著上升；4周暴露组的1C细胞显著高于2周组，2C细胞显著低于2周组。6.4mT 4周组1C、2C以及4C峰的DNA含量显著下降。6.4mT 2周组S期细胞百分比明显增加。 5．采用流式细胞精子染色质结构方法检测DNA变性精子的数量，结果显示DNA变性精子的数量(COMPαT)增多。 以上结果表明： 1．ELF EMFs导致雄性小鼠睾丸的重量和体积下降，精子数量、活动率下降，头部畸形率上升，从而影响了雄性小鼠的生育能力。 2．ELF EMFs引起雄性生殖能力损害可以由ROS所致性腺氧化损伤得到解释。ELF EMFs可以改变性腺组织的抗氧化能力。与睾丸相比，附睾的氧化还原平衡更易受到影响。 3．ELF EMFs造成ROS的积累，进而引起生殖细胞DNA损伤，引发细胞周期改变和精子染色质结构的HPRR不完全，干扰了精子发生，这可能是导致雄性小鼠生育能力下降的途径之一。 4.较长时间ELF EMFs暴露对雄性小鼠的生精过程以及精子产生不利影响。 5.ELF EMFs造成的生物效应具组织特异性。 本工作使我们得以从ROS所致性腺组织的氧化损伤乃至精子发生紊乱的侧面就ELF EMFs对雄性小鼠生殖的影响做出可能的解释，从而深化了我们对ELFEMFs影响雄性生殖的认识。ELF EMFs可能是导致雄性生育能力下降的物理性危险因子，建议加强对其监测并对长时间电磁场暴露下育龄男性给予防护措施。更多还原

【Abstract】 In recent years, growing attention has been focused on the possible effect of extremely low frequency electromagnetic fields (ELF EMFs) on human reproductive health. Some epidemiological and experimental studies have suggested that ELF EMFs is associated with male infertility. However limited experimental studies have not come at an exact conclusion. Present experiments were performed on healthy adult male mice. Male reproductive effects induced by exposure of 0.2~6.4mT 50Hz ELF EMFs for 2 or 4 weeks were observed through morphological, biochemical and cell-biological methods and approaches.The results are as follows:1. The testis weight and volume were decreased after EMFs exposure, and the effect of 4week EMFs exposure is more obvious than that of 2week exposure; No significant histopathological changes were observed in the testis of exposed mice. Sperm count and sperm motility were decreased and incidence of teratospermia was increased after EMFs exposure.2. After EMFs exposure, SOD and GSH-px activity were decreased. Anti OH capacity ,NO content were increased and MDA content was decreased in the epididymis.3. DMA damage were detected by single-cell gel electrophoresis assay. After exposure the relative tail length of the comets and cells with DNA migration were increased.4. The percentages and DNA content in different testis cell regions and percentages of testis cells in different cell phases were estimated by flow cytometry (FCM) . After 6.4mT exposure for 2 weeks, the percentage of 1C testis cells was significantly decreased. And the percentage of 2C cells was significantly increased after 4 weeks exposure. The percentage of 1C and 2C cells were significant increased and decreased respectively for 4 week exposure compared with 2week exposure. DNA content of the mice exposed to 6.4 mT for 4 weeks was significantly decreased. The cell percentage in Sphase was increased after 6 4mT exposure for 2 weeks. 5. The influence of ELF EMFs on sperm chromatin structure is detected bysperm chromatin structure assay. Spermatozoa with denatured DNA (cellsoutside the main population, COMP T) were increased after all EMFsexposure for 4 weeks. These results indicated that: 1 50Hz EMFs exposure induced the decreases in adult mice testis weight, testisvolume, sperm count and sperm motility, and the increases in the incidence ofteratospermia in mice. As a result, 50Hz EMFs may have the potential toimpair male fertility.2. 50Hz EMFs could interfere the balance between cellular oxidative and anti-oxidative processes in male gonad tissue and thereby induce oxidative damage The findings also suggest that epididymis may be more susceptible to the oxidative stress induced by EMFs.3. The oxidative damage could be one of the mechanisms by which EMFs caused adverse effects on male reproduction in mice. The accumulated reactive oxygen species could attack DNA, disturb sperm chromatin structure and cell cycle of spermatogenesis.4. The biological effects of ELF EMFs could be organ- and tissue-specific.5 Long-term exposure to EMFs may have adverse effects on spermatogenesis.To sum up, this study provides an insight into the possible adverse effects and potential mechanism of the ELF EMFs on male reproduction in mice It is suggested that ELF EMFs could cause oxidative stress in testis and epididymis tissue, damage DNA and chromatin structure, interfere cell cycle and as a consequence disturb spermatogenesis. While EMFs may act as a physical agent to impair male reproduction, environmental supervision as well as prevention and protective measure should be intensified on fertile male population.更多还原