Pocar P, Perazzoli F, Luciano A M, Gandolfi F
Department of Anatomy of Domestic Animals, University of Milan, Italy.
Mol Reprod Dev. 2001 Apr;58(4):411-6. doi: 10.1002/1098-2795(20010401)58:4<411::AID-MRD8>3.0.CO;2-R.
Polychlorinated biphenyls (PCBs) are one of the most persistent and widespread group of endocrine disrupting compounds in the ecosystem. High concentrations of these substances are known to be present in sewage sludge from industrial, agricultural, and domestic origin that is spread in increasing amounts on arable land and pasture as fertilizer and is found in water, representing an increasing risk for the reproductive health of farm animals. Objective of this study was to determine the impact of PCBs on maturation and developmental competence of cattle oocytes. Since PCBs are a family of 209 molecules present in the environment as a mixture, Aroclor-1254, a pool of more than 60 congeners, was used in these experiments as its composition is considered to be environmentally relevant. Cumulus-oocytes complexes were exposed during IVM to serial concentrations of Aroclor-1254 (between 1 microg/ml and 0.0001 microg/ml) and compared with control groups. Aroclor decreased the percentage of oocytes that reached metaphase II stage after 24 hr, at doses as low as 0.01 microg/ml. Groups treated with 0.001 microg/ml or above, showed an impaired fertilization rate and a dramatic increase of polyspermy. Moreover, exposure during maturation resulted in a reduced proportion of oocytes that cleaved and developed until blastocyst stage although no differences in embryo cell numbers were observed. The present study indicates that very low PCBs concentrations are sufficient to disrupt bovine oocyte maturation, its fertilization, and developmental competence. These results also provide a set of reference data for the assessment of the risk posed by these substances to animal reproductive health, though further work will be necessary to equate in vitro doses to in vivo exposures.
多氯联苯（PCBs）是生态系统中最持久、分布最广泛的一类内分泌干扰化合物。已知来自工业、农业和家庭的污水污泥中含有高浓度的这些物质，这些污泥作为肥料越来越多地施用于耕地和牧场，并且在水中也有发现，这对农场动物的生殖健康构成了越来越大的风险。本研究的目的是确定多氯联苯对牛卵母细胞成熟和发育能力的影响。由于多氯联苯是环境中以混合物形式存在的209种分子组成的家族，实验中使用了Aroclor - 1254（一种包含60多种同系物的混合物），因为其成分被认为与环境相关。卵丘 - 卵母细胞复合体在体外成熟（IVM）过程中暴露于一系列浓度的Aroclor - 1254（1微克/毫升至0.0001微克/毫升之间），并与对照组进行比较。低至0.01微克/毫升的剂量下，Aroclor降低了24小时后达到中期II期的卵母细胞百分比。用0.001微克/毫升及以上剂量处理的组，受精率受损，多精受精显著增加。此外，成熟过程中的暴露导致卵裂并发育至囊胚阶段的卵母细胞比例降低，尽管未观察到胚胎细胞数量的差异。本研究表明，极低浓度的多氯联苯就足以破坏牛卵母细胞的成熟、受精和发育能力。这些结果也为评估这些物质对动物生殖健康构成的风险提供了一组参考数据，不过还需要进一步的工作来使体外剂量与体内暴露量相等。
