Effects of Ethinylestradiol-Induced Cholestasis on Bile Flow and Biliary Excretion of Estradiol and Estradiol Glucuronide by the Rat

Abstract

The phenolic steroid hormones estrone and estradiol, are excreted in bile and undergo an enterohepatic circulation in the rat and in man. I t has been shown that high doses of exogenous estrogen may impair hepatic excretory function in human females and in the rat (1, 2 ) . There is also evidence that endogenous hormones may cause abnormalities of liver function or cholestasis during late pregnancy (3)(4)(5), and that in those individuals who have suffered from cholestatic jaundice of pregnancy or pruritus gravidarum, moderate or low dose of estrogen administered in the nonpregnant state will reproduce the symptoms and liver function test abnormalities that occurred during pregnancy (4, 5 ) . The present study was carried out to determine whether administered estrogen impairs bile flow and biliary excretion of labeled estrogen in the rat.Methods and Materials. Female Sprague-Dawley rats, weighing from 150 to 180 g were fed ethinylestradiol (0.5 mg in saline suspension, by oral tube) daily, for 9 days. Litter-mate control animals were similarly saline sham-fed. On the tenth experimental day common bile duct cannulation and femoral vein catheterization were performed with the rats under light ether anesthesia. Each animal was then confined to a modified plastic restraining cage. Constant intravenous hydration with 5% dextrose and saline solution administered by a Harvard infusion apparatus at a rate of 0.0764 ml/min, and constant room temperature conditions, 25-26', were maintained throughout the entire study. Public Health Service F2 A.M. -30,036.On the eleventh experimental day, 18-20 hr after surgery and 40-48 hr after the last dose of ethinylestradiol, a tracer dose of radioactive estrogen (estradiol or estradiol glucuronide) and bromsulfophthalein ( 10 mg) were administered intravenously via the femoral catheter, in 0.4 ml of 50% ethanolsaline solution, followed by a 1.0-ml saline flush. Bile was collected in 10-min fractions during the first hour, 15-min fractions during the second hour, 30-min fractions during the next 2 hr, and at 1-or 2-hr intervals up to a total of 9 hr. At the end of the collection periods, the animals were killed, the livers were examined grossly and under light microscopy with hematoxylin and eosin sections.Radioisotopes, estradiol-l7p-6, 7-3H, 5.6 Ci/mmole, istradiol-1 7P-4J4C, 8.18 mCi/ mmole and estradiol-6, 7-3H, 1 7/3-~-glucuronide, 1.0 Ci/mmole, were obtained from the New England Nuclear Corporation and were repurified by paper chromatography prior to use. The activity of the radioactive estrogen solutions to be administered was measured a t the time of each injection. Bile samples were measured for volume. Qualitative analysis for the appearance of bromsulfophthalein in the bile was made in all control and estrogentreated animals. Aliquots were taken for measurement of radioactivity. To each bile aliquot, 50 pl or less, was added 2 ml of ethanol and 10 ml of toluene-POPOP phosphor solution. Quench correction was carried out by the addition of an appropriate internal standard to ...

Profiling lipid metabolites yields unique information on sex- and time-dependent responses of fathead minnows (Pimephales promelas) exposed to 17α-ethynylestradiol

“…This includes alterations in cholesterol homeostasis. Effects on cholesterol can be elicited through a number of mechanisms including: increased low-density lipoprotein uptake (Kovanen et al 1979), altered bile acid synthesis and secretion (Gumucio and Valdivieso 1971;Kreek et al 1969), esterification reactions (Davis and Kern 1976), or changes in de novo synthesis (Fewster et al 1967;Humber et al 1962;Mukherje and Bhose 1968;Wade et al 1984). In contrast to the extensive number of studies conducted to determine the effects of estrogens on cholesterol metabolism in mammals, only a handful of studies have investigated the effects of estrogens on cholesterol homeostasis in fish (Khanna and Singh 1983;Samuelsson et al 2006;Sharpe and MacLatchy 2007;Wallaert and Babin 1992).…”

The effect of estrogen on bile formation in the rat

“…Kreek et al (14) have reported that in rats ethinyl estradiol profoundly delays the appearance of BSP at the common duct. In the experiments reported here the initial appearance of BSP was somewhat later in estrone-treated rats than in controls, but this change was too small to be verified statistically and much less than that reported by Kreek. In any event, a more reliable index of the time relationships is provided by the mean excretory transit time, i.e., the average time taken by BSP to traverse the liver cells and the biliary tree.…”

“…Scattered reports (6)(7)(8)(9) of cholestasis following the use of oral contraceptives have heightened this suspicion as have recent suggestions (10)(11)(12), that impaired hepatic excretion in the newborn may reflect, at least in part, a deleterious effect of maternal estrogen on the fetus. However one regards the circumstantial evidence implicating sex hormones in these clinical situations, it is clear that large doses of estrogen regularly impair BSP excretion in both rats (13,14) and people (10,15). Among a variety of natural and synthetic estrogens which share this capacity in the rat, estrone is reported to be most active (13).…”

Reversal of Ethinyl Estradiol-induced Bile Secretory Failure with Triton WR-1339

“…The causes(s) of bile secretorv failure (cholestasis) is unknown, but these agents have focused attentioIn oIn abnormalities in the hepatocyte. Ethinyl estradiol, a synthetic estrogen, has been extensively studiedl as a dcrug whiclh produces bile secretory failure characterized by (lecreases in the bile salt independent component of bile flow (2)(3)(4), the maximumti capacity to excrete organic anions such as bile acids (5), bilirubin (6), and bromosulfophthalein (4, 7) and decreased hepatic Na+-K+-ATPase activity (8,9). It has been suggested that this diffuse abnormality in biliary secretory processes is primarily the result of changes in membrane lipid structure (9).…”