Ethinylestradiol administration selectively alters liver sinusoidal membrane lipid fluidity and protein composition.
Ethinylestradiol administration selectively alters liver sinusoidal membrane lipid fluidity and protein composition.
复制标题
炔雌醇给药选择性地改变肝窦膜脂质流动性和蛋白质组成。
DOI：
10.1021/bi00411a008
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Simon,FR
中科院分区：
文献类型：
--
作者：
Rosario,J;Sutherland,E;Zaccaro,L;Simon,FR
1987年12月4日收到的修订稿摘要：大剂量给药可降低胆汁流量、Na，K-ATPase比活性和肝脏质膜流动性。用高纯度的肝窦和胆小管膜组分，观察了乙炔雌二醇对质膜组分的蛋白质、脂肪组成和流动性的影响。在正弦部分，乙炔雌二醇(EE)降低Na，K-ATPase活性(32%)，增加碱性磷酸酶(254%)、镁ATPase(155%)和160 kDa多肽(10倍)的活性。采用稳态和动态荧光偏振法研究膜脂结构。二苯基己三烯(DPH)在小管中的稳态极化显著高于正弦膜组分。乙炔雌二醇(每天5 mg/kg，连续5天)选择性增加正弦偏振值。探针2-和12-二甲氧基硬脂酸酯也表现出类似的变化。时间分辨荧光偏振测量表明，给予EE 5天并没有改变DPH寿命，但增加了有序分量(/“)，降低了旋转率(R)。但给药后第1天和第3天，低剂量(每天10-100 mg/kg，连续5天)，Na，K-ATPase、胆汁流量和顺序成分均发生改变，但旋转速度不变。用EE处理的大鼠的总肝窦膜脂制备的囊泡和磷脂囊泡显示DPH极化增加，完整的质膜部分也是如此。肝质膜组分的游离胆固醇和胆固醇/磷脂摩尔比没有变化，而酯化胆固醇含量在高剂量组增加，但不能增加低剂量的乙烯雌二醇。大剂量的乙烯雌二醇处理后，磷脂的极头基团和脂肪酸发生了轻微的变化，但鞘磷脂/磷脂酰胆碱的比值和饱和脂肪酸的百分比都没有改变。综上所述，低剂量和高剂量的乙烯雌二醇治疗可以选择性地增加肝窦状质膜有序成分。这种结构变化是由于极化脂成分的变化，而不是中性脂成分的变化。这些结果表明，雌激素可以选择性地改变质膜脂质和蛋白质结构域，这些变化可能是肝内胆汁淤积症发病机制中的一个组成部分。17α-乙炔基雌二醇(EE)是一种通常用于避孕药的雌激素类固醇，其给药与人和动物的肝内胆汁淤积有关(Plaa&Priestly，1977；Schreiber&Simon，1983；Metreau&Dhumeaux，1972)。在大鼠中，高剂量的EE减少胆汁流量和肝脏排泄有机阴离子的最大能力，如胆盐、胆红素和溴磺化邻苯二甲酸(Kaplowitz等人，1986；Simon&Arias，1973；Gumucio&Vadieso，1971)。先前使用电子自旋共振和荧光偏振技术的研究已经报道，服用EE后，肝脏质膜流动性降低(Davis等人，1979；Keefe等人，1979；Storch&Schachter，1984)。造成这种变化的脂质成分被不同地归因于胆固醇和/或胆固醇酯的增加(Davis等人，1979；Keefe等人，1979；Simon等人，1980)。对这一模型的研究主要集中在肝脏表面膜，特别是胆汁分泌衰竭发病机制中主要异常部位的管状区(Simon&Arias，1973)。然而，其他观察表明，…是正弦的
Revised Manuscript Received December 4, 1987 abstract: Administration of high-dose ethinylestradiol to rats decreases bile flow, Na, K-ATPase specific activity, and liver plasma membrane fluidity. By use of highly purified sinusoidal and bile canalicular membrane fractions, the effect of ethinylestradiol administration on the protein and lipid composition and fluidity of plasma membrane fractions was examined. In sinusoidal fractions, ethinylestradiol (EE) ad-ministration decreased Na, K-ATPase activity (32%) and increased activities of alkaline phosphatase (254%), Mg2+-ATPase (155%), and a 160-kDa polypeptide (10-fold). Steady-state and dynamic fluorescence polarization was used to study membrane lipid structure. Steady-state polarization of diphenylhexatriene (DPH) was significantly higher in canalicular compared to sinusoidal membrane fractions. Ethinylestradiol (5 mg/kg per day for 5 days) selectively increased sinusoidal polarization values. Similar changes were demonstrated with the probes 2-and 12-anthroyloxystearate. Time-resolved fluorescence polarization measurements indicatedthat EE administration for 5 days did notchange DPH lifetime but increased the order component (/„) and decreased the rotation rate (R). However, 1 and 3 days after EE administration and with low doses (10-100 Mg/kg per day for 5 days) the Na, K-ATPase, bile flow, and order component were altered, but the rotation rate was unchanged. Vesicles prepared from total sinusoidal membrane lipids of EE-treated rats, as well as phospholipid vesicles, demonstrated increased DPH polarization, as did intact plasma membrane fractions. Liver plasma membrane fractions showed no change in free cholesterol or cholesterol/phospholipid molar ratio, while esterified cholesterol content was increased with high-dose but not low-dose ethinylestradiol. High-dose ethinylestradiol treatment produced minor changes in phospholipid polar head groups and fatty acids; however, neither the sphingomyelin/phosphatidylcholine ratio nor the percent of saturated fatty acids was altered. In summary, the sinusoidal liver plasma membrane order component was selectively increased with low-and high-dose ethinylestradiol treatment. This structural change is due to changes in polarrather than neutral lipid composition. These results indicate estrogens may selectively alter plasma membrane lipid and protein domains, and these changes may be integral to the pathogenesis of intrahepatic cholestasis..^^. dministration of 17a-ethinylestradiol (EE), 1 an estrogenic steroid commonly used in birth control pills, is associated with intrahepatic cholestasis in man and animals (Plaa & Priestly, 1977; Schreiber & Simon, 1983; Metreau & Dhumeaux, 1972). In rats, high doses of EE reduce bile flow and the liver’s maximum capacityto excrete organic anions such as bile salts, bilirubin, and bromosulfophthalein (Kaplowitz et al., 1986; Simon & Arias, 1973; Gumucio & Vadivieso, 1971). Previous studies, using both electron spin resonance and fluorescence polarization techniques, have reported that liver plasma membrane fluidity is reduced following EE administration (Davis et al., 1979; Keefe et al., 1979; Storch & Schachter, 1984). The lipid components responsible for thischange have been variously attributed to increases in cholesterol and/or cholesterol esters (Davis et al., 1979; Keefe et al., 1979; Simon et al., 1980). Examination of this model has focused attention on the liver surface membrane and, in particular, the canal-icular domain as the primary site of abnormalities in the pathogenesis of bile secretory failure (Simon & Arias, 1973). However, other observations suggest the sinusoidal …