摘要
随着辅助生殖技术的开展，高功率阴道超声广泛用于卵泡监测、取卵及多胎妊娠减胎术等过程中。阴道超声辐照对生殖细胞及胚胎潜在的生物效应需受到重视。深入理解超声生物效应的产生机制将有利于更谨慎地临床应用。关于孕早期接受阴道超声辐照对人体胚胎及其发育环境可能的分子生物效应及其相应的信号转导途径，国内外尚未见报道。本研究的目的是探讨阴道超声辐照对人早孕绒毛细胞凋亡的影响及其信号转导路径。选择拟行人工流产的24例健康早孕妇女，随机分为四组：空白照射组(0-min)、照射10-min、20-min和30-min组。应用探头频率5.0-MHz的阴道诊断超声，按不同时间固定持续照射孕囊。照射后4小时取绒毛。琼脂糖凝胶电泳检测DNA降解片段。Western blot定量分析Caspase-3的激活和线粒体cytochrome C的释放。在阴道超声辐照10-min，20-min，30-min组，琼脂糖凝胶电泳显示特征性DNA降解片段。与0-min和10-min组比较，阴道超声辐照20-min和30-min组，绒毛细胞Caspase-3活性片段P17／P10的表达和cytochrome C的释放明显增加 (P＜0.01)。阴道
浙江大学医学院 博士学位论文
超声辐照诱导的细胞凋亡增加具有时间依赖性，以30Inin组最为明显。以
上结果表明，阴道超声辐照后，激活凋亡执行蛋白Caspase－3介导的人早
孕绒毛细胞凋亡级联反应。线粒体内源性死亡路径参与阴道超声辐照诱导
的人早孕绒毛细胞凋亡。为孕早期阴道超声的谨慎使用提供了分子学理论
依据。
In assisted reproductive technologies, high-power transvaginal ultrasonography is increasingly used to observe follicle growth or multifetal pregnancy reduction in the early stages of genesis. Its potential bioeffects for conceptus should be paid more attention. An understanding of mechanism by which bioeffect of ultrasound is produced is indispensable for prudent use. However, little is known about bioeffects of transvaginal ultrasound on early conceptus and the mechanism by which biological effects are produced. Our objective is to investigate the effect of exposure of human chorionic villi to transvaginal ultrasound in the first trimester of pregnancy on apoptosis and the underlying signal transduction pathway. 24 healthy women hi the first-trimester pregnancy were randomly divided into four groups: control group (0-min), experimental groups (10-min, 20-min, 30-min). According to different times, the site of the attached embryo was exposed to a fixed beam from transvaginal ultrasound with a 5.0-MHz trandu
cer. The chorionic villi
obtained 4h after exposure. DNA fragmentation was measured by 1.5% agarose gel electrophoresis. Activation of caspase-3 and cytochrome C release were analyzed by western blotting. Clean bands represented DNA fragmentation occurred after transvaginal ultrasound exposure in 10-min, 20-min and 30-min groups. In contrast with the Omin- and lOmin- groups, cleavage products of active caspase-3 and cytochrome C release significantly increased in 20-min and 30-min groups in a time-dependent manner. We show that exposure to transvaginal ultrasound activates effector caspase-3 mediated apoptotic cascade of chorionic villi in the first-trimester pregnancy. This occurs through the intrinsic death pathway involving in mitochondria! cytochrome c release. Our findings provide a molecular rationale for discriminate use of transvaginal ultrasound at the early stage of pregnancy.
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