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题名	多溴二苯醚在胚胎和脑中的富集及传输规律研究
作者	赵亚娴
学位类别	博士
答辩日期	2014-05
授予单位	中国科学院研究生院
授予地点	北京
导师	郑明辉，秦占芬
关键词	多溴二苯醚 胚胎 富集 血脑屏障 体外模型 Polybrominated diphenyl ethers fetus bioaccumulation blood brain barrier in vitro model
其他题名	Bioaccumulation and transport of polybrominated diphenyl ethers (PBDEs) in the fetus and brain
学位专业	环境科学
中文摘要	多溴二苯醚（PBDEs）作为一类持久性有机污染物，其对神经发育的影响备受关注。但是目前关于PBDEs的胎儿早期暴露和脑中富集及血脑传输规律的认识还很有限。围绕这三个问题，本论文开展了以下研究： 1. PBDEs的胎儿早期暴露：胎儿发育早期对化学污染物的损伤最为敏感，关于此阶段的PBDEs暴露还少有报道。本研究以浙江台州电子垃圾拆解区周边区域为研究现场，采集配对早期流产胚胎（孕龄：10 ~ 13周）、早期胎盘以及母亲静脉血等人体样品，开展了PBDEs在早期胚胎中的富集及血胎传输研究。结果发现，所有样品中均有PBDEs的存在，且胚胎中含量显著低于母血含量，显示妊娠早期PBDEs即可进入胎儿体内。胚胎、胎盘和母血配对样品中PBDEs含量显著相关，显示通过母血中PBDEs含量可估算早期胚胎中PBDEs的暴露负荷。由PBDEs同类物在胚胎、胎盘以及母血中的分布特征分析妊娠早期血胎传输，发现低溴代物较高溴代物更易透过胎盘屏障进入胎儿体内富集，而高溴代物更易被胎盘组织滞留。 2. PBDEs在动物脑中富集：鉴于目前有关PBDEs脑中富集和血脑传输规律认识的缺乏，尤其是人脑材料的不可获得性，本研究采集台州地区一个电子垃圾拆解点的野生鱼、蛙、鸡、鸭以及家鼠等生物样品，开展了PBDEs在不同生物脑中的富集研究。结果发现除鱼外，其他生物脑中PBDEs的含量均显著低于肝脏和肌肉组织中含量，这一规律可能与血脑屏障（BBB）的屏障作用有关。进一步用PBDEs浓度的脑肝比粗略表征PBDEs通过BBB在脑中富集的能力，发现鱼脑富集PBDEs的能力最强，蛙脑次之，鸡、鸭和家鼠的脑最弱。从不同同类物的脑肝比来看，较高等生物种的低溴代物比高溴代物更易在脑中富集，这一规律在家鼠中最为明显，显示较高等生物的BBB对高溴代物的屏障作用可能强于对低溴代物的屏障作用。 3. 血脑屏障体外模型：为验证以上关于PBDEs血脑传输规律的推测，并为更多有机污染物的血脑传输研究提供一种有效的手段，本研究借鉴药物血脑传输研究的模型，在本实验室建立起Sprague-Dawley（SD）大鼠原代脑微血管内皮细胞（BMECs）和星形胶质细胞（Astrocytes）在transwell小室中的细胞共培养BBB模型。通过检测细胞形态、紧密连接、跨膜电阻值以及指示物荧光素钠和FD-40S的渗透系数等指标对模型的质量进行鉴定，结果显示该模型在屏障完整性和渗透功能等方面保留了良好的在体BBB特性，可以用于有机污染物的血脑传输研究。 4. PBDEs血脑传输规律：利用建立的体外BBB模型，首次对PBDEs的血脑传输规律开展研究，发现四溴-十溴取代PBDEs的渗透系数范围为3.86 × 10-7 ~ 3.27 × 10-6 cm/s，整体上渗透系数随溴原子取代数目的增加而降低。相关性分析结果显示，同类物渗透系数与其分子量、Log Kow、分子极性、分子极性表面积（SAG）、分子体积、qBr+和qO-呈显著负相关，与Ehomo、Elumo呈显著正相关。最后，利用QSAR模型建立了PBDEs透过BBB的单因素（DP02）预测方程。       综上所述，本研究获得了人体早期胚胎PBDEs暴露和生物体脑组织PBDEs富集及传输的数据，可为胎儿PBDEs暴露风险及发育神经毒性研究提供支持。同时，借鉴药物传输的BBB体外模型，实验室研究了PBDEs的血脑传输规律，与现场监测获得的结果基本吻合。这是利用体外BBB模型研究有机污染物血脑传输规律的首次尝试，为研究有机污染物的神经暴露风险提供了一个新的思路。
英文摘要	Polybrominated diphenyl ethers (PBDEs), one class of persistent organic pollutants, have aroused great attention due to developmental neurotoxicity. However, the current understanding of their prenatal exposure, accumulation in the brain, and transport across the blood brain barrier (BBB) is very limited. In this dissertation, the following studies were carried out: 1. Prenatal exposure to PBDEs: Fetal development is sensitive to chemicals during the early pregrancy, but data concerning prenatal exposure to PBDEs have been limited. PBDEs were analyzed in matched aborted fetuses, placentas, and maternal blood samples (10 ~ 13 weeks gestation) from a hospital located near electronic waste (e-waste) recycling sites in Taizhou. PBDEs were detected in all human samples, and the concentrations of PBDE in early fetuses were significantly lower than those in maternal blood, indicating that PBDEs can enter the fetus during the first trimester. Significant correlations were found between ΣPBDE concentrations in the matched matrices, suggesting that the fetus exposure level to PBDEs can be estimated by the concentrations in maternal blood. PBDE congener profiles indicated that low brominated congeners could cross the placenta more easily than high brominated congeners, while high brominated congeners tended to accumulate in the placenta. 2. PBDE accumulation in the brain: Given the difficulty in obtaining human brain tissue, we analyzed PBDEs in fish, frogs, chickens, ducks, and mice collected in one e-waste recycling site in Taizhou to investigate PBDE accumulation in the brain and BBB transfer. It was found that PBDE levels in brain tissues were significantly lower than liver and muscle tissues in all animals except fish. BBB may prevent PBDEs from entering into the brain tissues. Brain/liver concentration ratios(B/L) were used to evaluate bioaccumulation in the brain and the transfer efficiency across BBB. The results show that PBDEs has the highest bioaccumulation in the fish brain, followed by frogs, chickens, ducks, and mice. The different B/L ratios among PBDE congeners show that the BBB in high level species (in particular mice) might prevent high brominated congeners from entering the brain tissue more efficiently than it does low brominated congeners. 3. Establishment of in vitro BBB model in our laboratory: To verify the above speculation of PBDE transport across the BBB, and to provide an effective tool for organic pollutant research, an in vitro BBB model is needed. Co-culture model of BMECs and astrocytes from Sprague Dawley (SD) rats in the transwell chamber, which has been used for pharmaceuticals, was established in our laboratory. The physical integrity and permeability functions of BBB were verified by cellular morphology, tight junction, TEER values, and the permeability of sodium fluorescein and FD-40S. The results demonstrate that the in vitro BBB model we established can be used to study the transport of organic pollutant across the BBB. 4. PBDE transfer across the BBB: PBDE transport across the BBB was investigated for the first time using the in vitro co-culture model. The BBB permeability coefficients of PBDE congener (from tetra-BDEs to deca-BDEs) ranged from 3.86 × 10-7 to 3.27 × 10-6 cm/s. The permeability coefficients tended to decrease as the number of bromine atoms increase. Significant negative correlations were observed between PBDE permeability coefficients and molecular weights, Log Kow, molecular polarizability, SAG, molecular volume, qBr+, and qO-. In addition, significant positive correlations were found between the PBDE permeability coefficients and the energy of the occupied molecular orbital (Ehomo and Elumo). Finally, QSAR models were used for describing the quantitative relationship between the structure factor (DP02) and transport of PBDEs across the BBB.       In summary, data on human prenatal exposure and PBDE bioaccumulation in the brain were obtained, providing a support for fetal exposure risk and developmental neurotoxicity. Meanwhile, PBDE transport across the BBB was investigated using the co-culture in vitro BBB model, and the findings agreed with the observations from the field monitor. This is the first attempt to study the transport of organic pollutants across BBB using an in vitro model, and it provides a new view for neurotoxicity assessment of organic pollutants.
公开日期	2015-07-07
内容类型	学位论文
源URL	[http://ir.rcees.ac.cn/handle/311016/15622]
专题	生态环境研究中心_环境化学与生态毒理学国家重点实验室
推荐引用方式 GB/T 7714	赵亚娴. 多溴二苯醚在胚胎和脑中的富集及传输规律研究[D]. 北京. 中国科学院研究生院. 2014.

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