PBC EFFECTS ON UTERINE MUSCLE

本研究的总体目的是了解多氯联苯（PCBs）如何改变子宫收缩，以提高对多氯联苯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。在动物中，多氯联苯对妊娠期长短的影响取决于同系物或混合物。介导多氯联苯对分娩影响的机制尚不清楚。这项建议是研究选择的多氯联苯，表现出急性刺激或抑制活性在怀孕子宫。此外，将研究雌激素多氯联苯对子宫活动的长期影响。我们提出以下假设和具体目的：(1)子宫强张性多氯联苯抑制K+通道，从而使细胞膜去极化，然后激活电压操作的钙通道，通过膜片钳程序和细胞内探针的荧光检测促进细胞内钙浓度增加和收缩。(2)子宫强直性多氯联苯通过选择性作用于子宫平滑肌细胞亚群来刺激收缩频率，这些细胞可能是子宫的起搏器。本研究将分离缺乏起搏器样细胞的细胞和子宫组织，以研究多氯联苯对离子通道活性的选择性作用。细胞分离和解剖策略将用于从大鼠子宫中分离假定的起搏器和非起搏器细胞和组织。肠道起搏器细胞缺陷的突变小鼠将被用作子宫起搏器子宫缺陷的潜在来源。(3)抑制性多氯联苯通过氧化应激介导的子宫肌间隙连接抑制，降低了子宫收缩的力量，促进子宫收缩的非同步性。该目标将使用生化和组织化学方法来测量多氯联苯诱导的氧化应激、超氧化物和间隙连接蛋白的氧化。(4)雌激素性多氯联苯通过雌激素受体依赖机制，通过增加催产素受体和间隙连接的表达，促进子宫收缩。该目的将通过western blot测量pcb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存在的环境污染物。通过增加我们对多氯联苯在怀孕子宫中的作用的了解，这些实验的结果将有助于改进对孕妇的风险评估，并可能解释先前关于多氯联苯改变分娩的报道。

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.