PAEs通过干扰胎盘甲状腺素转运介导神经发育毒性的作用机制

Phthalates exposure during pregnancy may result in the neurodevelopmental disorders in offspring by interfering with the placental transportation of maternal thyroid hormones (THs). First, nested in the Ma’anshan Birth Cohort (MABC) study, the THs transport system related protein levels in the placenta will be detected by suspension liquid protein chip, to investigate the associations between phthalates exposure and the THs transport system related protein and the delayed development of childhood cognition and executive function. Secondly, to explore the mechanisms of the placental THs transport system mediating the relationship between phthalates exposure and the neurodevelopmental toxicity, phthalates will be administered to female mice during the period from the neural tube closure to the thyroid hormone beginning to synthesize. We will detect the capacity of the placenta to transport T4, and the mRNA and protein levels of placental THs transport system. The nerve cell proliferation and migration will be labeled with BrdU. The learning and memory of mice pups will be measured using the Morris maze. Furthermore, we will estimate the uptake and transport of the fluorescence tracer-labeled transthyretin in human placental trophoblast cells, and verify the effect of phthalates exposure on the transcription and translation of THs transport related proteins. Finally, a nested case-control study will be conducted to demonstrate the hypothesis of the transcriptional expression mechanism, and further to clarify the fact that phthalates exposure resulting in the delayed development of childhood cognition and executive function is through interfering with the placental transportation of maternal THs. This study will provide the scientific evidence and new clues for exploring the target of prevention and control nerve damage in offspring induced by prenatal phthalates exposure.

孕期PAEs暴露可能通过干扰母体甲状腺素经胎盘转运导致子代神经发育障碍。本项目将依托马鞍山优生优育队列，液相蛋白悬浮芯片检测胎盘甲状腺素转运相关蛋白，解析PAEs暴露、甲状腺素转运相关蛋白与儿童认知和执行功能发育迟缓间关系；在胚胎神经管闭合至甲状腺素开始合成期间PAEs染毒母鼠，检测胎盘转运T4能力，分析胎盘甲状腺素转运体系mRNA和蛋白水平，BrdU标记神经细胞增殖迁移，水迷宫测试仔鼠学习记忆，揭示PAEs干扰甲状腺素经胎盘转运致神经发育毒性机制；利用人胎盘滋养细胞，观察荧光标记甲状腺素运载蛋白摄取转运，验证PAEs对甲状腺素转运相关蛋白转录和翻译的影响；再用巢式病例对照研究设计，验证转录表达机制结果，阐明孕期PAEs暴露干扰胎盘甲状腺素转运体系引起儿童认知和执行功能发育迟缓的机制。为探索孕期PAEs暴露诱发子代神经损害防控靶标提供理论依据和新线索。

邻苯二甲酸酯类（PAEs）是广泛存在的环境内分泌干扰物，可干扰性激素和甲状腺素（THs），孕期暴露可能会影响子代神经发育，胎盘在其中可能起到重要中介作用。本项目采用人群与实验室研究相结合，体内与体外实验研究相结合的方法，研究孕期暴露PAEs对子代神经发育的不良影响及持续效应，胎盘和脑的甲状腺素转运及功能系统在其中的作用；社区老年人群PAEs暴露水平及其与肥胖、抑郁的关联，以及炎症因子的中介效应。实验研究发现：在孕第9天至16天进口灌胃染毒DEHP，在不影响母鼠一般状况和THs的剂量条件下，羊水及胎盘中DEHP代谢物含量随着DEHP剂量增加而增加，子代神经发育受到影响，表现为雌性子代自幼年期即开始出现焦虑样行为，到成年期还出现抑郁样行为；雄性子代自幼年期即开始出现学习记忆能力下降；老年期雌雄子代均出现明显的学习记忆能力受损。虽然母鼠THs未受影响，但是胎盘和羊水中THs水平明显下降，胎盘和胎脑中THs转运体MCT8、脱碘酶2（Dio2）和THs受体的表达下调，而脱碘酶3（Dio3）的表达上调。DEHP可下调人胎盘滋养层细胞HTR-8/SVneo细胞甲状腺素转运蛋白TTR表达，抑制TTR内吞。人群研究发现：社区老年人PAEs体内负荷与全身肥胖正相关，且MBP 水平升高与男性腹型肥胖正相关；高水平MEHP、MBzP 和 MBP与老年抑郁评分升高相关，而慢性抑制可能起到部分中介作用。还发现，老年人Sr（锶）和Ba（钡）的体内负荷均与老年抑郁症状风险正相关。研究结果提示PAEs的神经（发育）毒性发展隐匿，影响持久，应予以重视。