PBC EFFECTS ON UTERINE MUSCLE

本研究的总体目标是了解多氯联苯（PCBs）如何改变子宫收缩，以提高对PCBs对孕妇及其后代的潜在风险的认识。多氯联苯暴露与妇女妊娠期缩短有关。在动物体内，多氯联苯会增加、减少或对妊娠期长短没有影响，这取决于其同系物或混合物。介导多氯联苯对分娩影响的机制尚不清楚。这项建议是研究选定的多氯联苯，表现出急性刺激或抑制活动，在怀孕的子宫。此外，还将研究雌激素多氯联苯对子宫活动的长期影响。我们提出了以下假设和具体目标：（1）子宫收缩性PCB抑制K+通道，从而使细胞膜去极化，然后激活电压操纵的钙通道，促进细胞内钙浓度增加和收缩使用膜片钳程序和细胞内探针的荧光检测。(2)子宫收缩性多氯联苯通过选择性地作用于子宫平滑肌细胞亚群来刺激收缩频率，子宫平滑肌细胞可能是子宫的起搏器。这一目标将分离出缺乏起搏器样细胞的细胞和子宫组织，以研究PCB对离子通道活性的选择性作用。将使用细胞分离和解剖策略从大鼠子宫中分离推定的起搏标记和非起搏细胞和组织。肠起搏细胞缺陷的突变小鼠将被用作子宫起搏器缺陷的潜在来源。(3)抑制性多氯联苯通过氧化应激介导的子宫肌层缝隙连接的抑制，降低子宫收缩的力，促进子宫收缩的去平滑肌化。这一目标将使用生物化学和组织化学的方法来衡量多氯联苯诱导产生的氧化应激，超氧化物和间隙连接蛋白的氧化。(4)雌激素多氯联苯通过雌激素受体依赖性机制增加催产素受体和间隙连接的表达，从而促进长期接触的子宫收缩。这一目标将通过蛋白质印迹法测量多氯联苯诱导的催产素受体和间隙连接蛋白丰度的变化。多氯联苯是孕妇可能接触到的广泛传播的环境污染物。通过增加我们对多氯联苯在怀孕子宫中作用的了解，这些实验的结果将有助于改善对孕妇风险的评估，并可能解释以前的报告，即多氯联苯改变分娩。

The overall objective of this research is to understand how polychlorinated biphenyls (PCBs) alter uterine contraction, in order to improve knowledge of the potential risks of PCBs to pregnant women and their offspring. PCB exposure is associated with decreased gestation length in women. In animals, PCBs increase, decrease or have no effect on gestation length depending on the congener or mixture. The mechanism(s) that mediate PCB effects on parturition are unknown. This proposal is to study selected PCBs that exhibit acute stimulatory or inhibitory activity in the pregnant uterus. Also, estrogenic PCBs will be studied for long-term effects on uterine activity. We propose the following hypotheses and specific aims: (1) Uterotonic PCBs inhibit K+ channels and thereby depolarize the cell membrane, which then activates voltage-operates calcium channels to promote increased intracellular calcium concentration and contractions using patch clamp procedures and fluorescence detection of intracellular probes. (2) Uterotonic PCBs stimulate contraction frequency by selectively acting on a subpopulation of uterine smooth muscle cells that may be the pacemarkers of the uterus. This aim will isolate cells and uterine tissues that are deficient in pacemaker-like cells to investigate selective PCB actions on ion channel activities. Cell isolation and dissection strategies will be used to separate putative pacemarker and non-pacemaker cells and tissue from rat uterus. Mutant mice deficient in pacemaker cells of the intestine will be used a potential source of uteri deficient in uterine pacemakers. (3) Inhibitory PCBs decrease the force the promote desynchronization of uterine contractions of uterine contractions by oxidative stress-mediated inhibition of myometrial gap junctions. This aim will use biochemical and histochemical approaches to measure PCB-induced generation of oxidative stress, superoxide, and oxidation of gap junction proteins. (4) Estrogenic PCBs promote uterine contraction with long-term exposure by increasing expression of oxytocin receptors and gap junctions through an estrogen receptor-dependent mechanism. This aim will measure by western blot PCB-induced changes in abundance of oxytocin receptors and gap junction proteins. PCBs are wide spread environmental contaminants to which pregnant women may be exposed. By increasing our understanding of PCB actions in the pregnant uterus, the results from these experiments will contribute to improved assessment of risk to pregnant women and may explain previous reports that PCBs alter parturition.