中文摘要：

目的：建立孕期苯巴比妥暴露所致的IUGR模型,观察胎肾上腺胆固醇供应关键基因——清道夫受体B类I型（scavenger receptor class B type I,SR-BI）与乙酰乙酰辅酶A合成酶（acetoacetyl-CoA synthetase,AACS）的表达与DNA甲基化修饰改变,验证此关键基因的DNA高甲基化作为胎肾上腺化合物发育毒性评价标志物的可能性。方法：健康Wistar孕鼠于受孕第7~17天灌胃给予50 mg·kg-1·d-1苯巴比妥或等量生理盐水,孕第17天处死,记录胎鼠体质量与胎盘重量,计算宫内发育迟缓（intrauterine growth retardation,IUGR）发生率。收集胎肾上腺用于透射电镜、荧光实时定量反转录PCR（reverse-transcription PCR,RTPCR）及亚硫酸氢盐测序PCR（bisulfite sequencing PCR,BSP）检测。结果：与对照组相比,苯巴比妥暴露组胎鼠体质量与胎盘重量均降低（P〈0.01）,IUGR发生率升高（P〈0.01）;透射电镜结果显示,胎肾上腺皮质细胞表现出线粒体水肿、胞浆内空泡等现象;RT-PCR检测结果显示,SR-BI与AACS表达降低（P〈0.05,P〈0.01）;BSP结果显示,SR-BI与AACS近端启动子区DNA甲基化频率升高（P〈0.01）。结论：孕期苯巴比妥暴露所致IUGR模型中,胎肾上腺组织结构受损,胆固醇供应关键基因SR-BI与AACS的mRNA表达改变,SR-BI与AACS的DNA高甲基化可作为潜在的化合物发育毒性评价标志物。

英文摘要：

OBJECTIVE To establish intrauterine growth retardation （IUGR） model induced by prenatal phenobarbital expo- sure,investigate changed expression and DNA methylation of scavenger receptor class B type I （SR-BI） and acetoacetyl-CoA synthetase （AACS）, key genes about cholesterol supply in fetal adrenals, and verify roles of these genes in evaluating com- pound-induced developmental toxicity on fetal adrenals. METHODS Pregnant Wistar rats were intragastrically treated with 50 mg/kg d phenobarbital or the same volume of saline from gestational day （GD） 7 to 17. On GD17, pregnant rats were sacri- ficed. Fetal body weights and placenta weights were recorded, and IUGR rates were calculated. Fetal adrenals were collected for analysis of transmission electron microscope （EM）, real-time reverse-transcription PCR （RT-PCR）, and bisulfite sequencing PCR （BSP）. RESULTS Compared with controls, fetal body weight and placenta weights were significantly lower in nicotine group （P〈0. 01 ）, and IUGR rates were significantly higher （P〈0. 01 ）. EM results revealed that phenobarbital-treated adreno- cortical cells showed mitochondrial edema and intracytoplasmic vacuoles. RT-PCR results displayed that expression of SR-BI and AACS were decreased （P〈0. 05 ,P〈0. 01）. BSP results showed that methylation rates of SR-BI and AACS proximal pro- moter were increased （P〈0. 01）. CONCLUSION There are histological changes and decreased mRNA expression of SR-BI and AACS,key genes about cholesterol supply, in fetal adrenals of prenatal phenobarbital exposure induced IUGR. In addition, increased DNA methylation of SR-BI and AACS can be potential markers evaluating compound induced developmental toxicity on fetal adrenals.