Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-75007 Uppsala, Sweden.
Aquat Toxicol. 2010 Oct 1;100(1):30-7. doi: 10.1016/j.aquatox.2010.07.010. Epub 2010 Jul 13.
The bromophenol 2,4,6-tribromophenol (TBP) is widely used as an industrial chemical, formed by degradation of tetrabromobisphenol-A, and it occurs naturally in marine organisms. Concentrations of TBP in fish have been related to intake via feed, but little is known about effects on fish health after oral exposure. In this study, we exposed adult male and female zebrafish (Danio rerio) to TBP via feed in nominal concentrations of 33, 330, and 3300 μg/g feed (or control feed) for 6 weeks to assess the effects of TBP on reproductive output, gonad morphology, circulatory vitellogenin levels, and early embryo development. The aim was also to investigate the extent to which TBP was metabolised to 2,4,6-tribromoanisole (TBA) in dietary exposed zebrafish, and the amounts of TBP and TBA found in offspring. After 6 weeks of exposure, we found about 3% of the daily dose of TBP in adult fish and the mean concentration of TBA was 25-30% of the TBP concentration. TBP and TBA were detected in offspring with wet weight-based egg/fish concentration ratios well below one. Exposure to TBP significantly reduced the fertilization success and disturbed the gonad morphology, i.e. fewer spermatid cysts in males and increased presence of atretic follicles and oocytes with decreased vitellogenesis in females. In females, the disturbed gonad morphology was accompanied by increased levels of circulating vitellogenin. Significant effects were observed at 3300 μg/g feed. Offspring early development was not significantly affected, but yolk-sac oedema tended to increase in frequency in exposed groups with time. Our results show that dietary exposure to TBP, at concentrations found in marine organisms that are part of the natural diet of wild fish, can interfere with reproduction in zebrafish. We also observed low accumulation from feed of TBP in zebrafish and biotransformation of TBP to TBA. This is the first paper showing gonadal histopathological changes and effects on fertility in TBP exposed fish.
2,4,6-三溴苯酚（TBP）是一种广泛应用的工业化学品，由四溴双酚 A 降解形成，也存在于海洋生物体内。鱼类中 TBP 的浓度与通过饲料摄入有关，但关于口服暴露后对鱼类健康的影响知之甚少。在这项研究中，我们通过饲料以 33、330 和 3300μg/g 饲料（或对照饲料）的名义浓度将成年雄性和雌性斑马鱼（Danio rerio）暴露于 TBP 中 6 周，以评估 TBP 对生殖输出、性腺形态、循环卵黄蛋白原水平和早期胚胎发育的影响。我们的目的还在于研究 TBP 在膳食暴露的斑马鱼中代谢为 2,4,6-三溴苯甲醚（TBA）的程度，以及在后代中发现的 TBP 和 TBA 的量。暴露 6 周后，我们发现成年鱼中每天剂量的 TBP 约为 3%，TBA 的平均浓度为 TBP 浓度的 25-30%。TBP 和 TBA 都存在于幼鱼中，其湿重基础上的卵/鱼浓度比远低于 1。TBP 暴露显著降低了受精成功率并扰乱了性腺形态，即雄性精囊内的精子数量减少，而雌性的闭锁卵泡和卵母细胞增多，卵黄生成减少。在雌性中，扰乱的性腺形态伴随着循环卵黄蛋白原水平的升高。在 3300μg/g 饲料的浓度下观察到显著的影响。幼鱼早期发育没有受到显著影响，但随着时间的推移，暴露组的卵黄囊水肿频率增加。我们的结果表明，在海洋生物中发现的浓度下通过饲料暴露 TBP，而这些浓度是野生鱼类自然饮食的一部分，会干扰斑马鱼的繁殖。我们还观察到 TBP 在斑马鱼中的低积累和 TBP 向 TBA 的生物转化。这是第一篇显示 TBP 暴露鱼类性腺组织病理学变化和对生育能力影响的论文。
