Estradiol Glucuronide Research Articles

Biliary excretion of estrone metabolites in the rat

We previously reported that sulfobromophthalein infusion inhibited the biliary excretion of estradiol glucuronides, whereas dibromosulfophthalein had no effect. In the present study, we examined the biliary excretion of estrone metabolites in rats. Biliary excretion of a tracer dose of intravenously injected [ 3H]estrone to control rats or EHBR and effects of the infusion of sulfobromophthalein and dibromosulfophthalein were studied. Biliary excretion of estrone metabolites was delayed in EHBR. Analysis of the biliary estrone metabolites revealed a marked decrease of the glucuronides in EHBR. Sulfobromophthalein and dibromosulfophthalein infusion (0.2 μmol/min/100 g b.wt.) inhibited the biliary excretion of estrone metabolites. However, the decrease in biliary excretion of the glucuronides was observed only with sulfobromophthalein that is excreted mainly as the glutathione conjugate. These findings indicate that glucuronides of estrone and its metabolites are partly excreted into bile by a canalicular organic anion carrier for sulfobromophthalein-glutathione, but not for dibromosulfophthalein.

Similarities and differences in the glucuronidation of estradiol and estrone by UDP-glucuronosyltransferase in liver microsomes from male and female rats

In this study, we evaluated the effects of pH, in vitro enzyme inhibitors, in vivo enzyme inducers, age, and sex on the glucuronidation of estradiol and estrone by rat liver microsomes. Although the pH dependence curves for the glucuronidation of estradiol and estrone were similar, the pH dependence curves for these estrogens by liver microsomes from adult male rats were very different from those by liver microsomes from adult female rats. These results suggest that liver microsomes from adult male and female rats have different estrogen glucuronosyltransferases. Liver microsomes from immature or adult female rats catalyzed the glucuronidation of estrone and estradiol more rapidly than liver microsomes from age-matched male rats. Intraperitoneal injection of sodium phenobarbital (75 mg/kg/day) or dexamethasone (75 mg/kg/day) into immature or adult male or female rats for 3–4 days resulted in a 33–58% increase in liver microsomal glucuronosyltransferase activity for estradiol, but there was little or no stimulatory effect on glucuronosyltransferase activity for estrone. Treatment of immature or adult male or female rats with 3-methylcholanthrene (25 mg/kg/day) for 3–4 days did not stimulate liver microsomal glucuronosyltransferase activity for estradiol or estrone, but the glucuronidation of 4-nitrophenol was stimulated several-fold. The in vitro addition of testosterone had a strong inhibitory effect on the glucuronidation of estradiol and estrone by liver microsomes from both adult male and female rats, whereas the in vitro addition of 4-nitrophenol had a slightly greater inhibitory effect on the glucuronidation of estradiol and estrone by adult male liver microsomes than by adult female liver microsomes. In conclusion, our results suggest that male and female rat livers have different estrogen glucuronosyltransferases and that the glucuronidation of estradiol, estrone, and 4-nitrophenol is catalyzed by different glucuronosyltransferases that are under different regulatory control.

Determination of pregnancy and estimation of litter size in gilts based on concentration of estrone glucuronide and estradiol glucuronide in plasma

Three experiments were conducted to determine the concentration of estradiol glucuronide (E 2G), and estrone glucuronide (E 1G) in the blood of gilts after mating (Day 0). Blood samples were taken from 20 mated gilts at weekly intervals from Day 14 to Day 34 and analyzed by radioimmunoassay (RIA) for concentration of E 2G and E 1G. The concentrations of both hormones rose from about Day 19 to a peak at Day 26 and then declined. The concentration of E 2G rose to 1700 pg ml −1 and E 1G rose to 8000 pg ml −1 at Day 26. Eleven mated gilts in a second study were bled on Days 20, 22, and 24 and plasma analyzed for E 2G and E 1G. At slaughter on Days 29–35, gilts with more than 100 pg ml −1 of E 2G or more than 1000 pg ml −1 of E 1G on Day 20 or later were pregnant. In a third study, 31 gilts were bled at 48 h intervals from Day 20 to 28 and plasma was analyzed for concentration of E 2G and E 1G. All gilts with over 100 pg ml −1 of E 2G and 30 of 31 with over 1000 pg ml −1 of E 1G were pregnant when killed at Days 30–35. When gilts were classified according to the concentration of E 2G at Day 20, 86% of gilts with over 200 pg ml −1 had eight fetuses or more and at Day 24, 77% of gilts with over 1100 pg ml −1 had eight or more fetuses. When gilts were sorted on the basis of over 1500 pg ml −1 on Day 20 and on Day 22 for over 3400 pg ml −1 of E 1G, the percentages of correct classification for eight or more fetuses were 87% and 81% respectively. Concentration of E 2G or E 1G from Day 20 to 28 after mating can be used to detect pregnancy and estimate litter size at the time of analysis.

Serum and urinary concentrations of sex hormones and genital swelling during the menstrual cycle of the gibbon

The relationship between sex hormone concentrations and female genital swelling during the menstrual cycle in the monogamous gibbon was comparable with that of polygamous female primates, such as the chimpanzee, which live in multimale groups and have larger swellings. The data, therefore, support the hypothesis proposed by C. R. Carpenter more than 50 years ago, that the gibbon's genital swelling, like that of other female primates, reflects basic physiological processes associated with progress of the menstrual cycle. Genital swelling increased during the follicular phase with increasing concentrations of oestradiol and oestrone glucuronide, reached maximal swelling in association with the mid-cycle peaks in the oestrogens and LH and began detumescence with the initial increases in progesterone during the luteal phase. The data also suggest that the menstrual cycle of the gibbon is shorter than previously reported, since cycles of 19-22 days exhibited hormone patterns that are consistent with ovulation. The genital swelling of the female gibbon is a useful marker for monitoring progress of the menstrual cycle and the presumptive time of ovulation.

Can urinary pyridinium crosslinks and urinary oestrogens predict bone mass and rate of bone loss after the menopause?

We measured urinary pyridinoline and deoxy-pyridinoline by high performance liquid chromatography, and urinary oestrogens by radioimmunoassay, in 68 healthy postmenopausal women to evaluate these assays for the prediction soon after the menopause of the risk of developing osteoporotic fractures in later life. Change in forearm bone mineral content was assessed by single photon absorptiometry over 4 years. Although there was no significant correlation between the pyridinium crosslinks and urinary oestrogens, we found that up to 58% of the variation in the rate of loss of bone mineral content in women soon after the menopause could be explained by pyridinoline and oestradiol glucuronide assays together with body mass index. Measurement of the urinary pyridinium crosslinks and oestradiol glucuronide may make a significant contribution to a biochemical screening procedure for future osteoporotic fracture.

Potential value of urinary oestrogen assays in the identification of fast bone losers after the menopause.

We determined the rate of change of bone mineral content (BMC) in the distal forearm of 89 healthy postmenopausal women by single-photon absorptiometry. The BMC measurements were taken at 6- or 12-monthly intervals for up to 4 years. Urinary oestrogen excretion and anthropometry were assessed at the time of the first BMC measurement. Urinary oestradiol glucuronide (E2G) excretion was related to the rate of change of 'proximal' BMC in women 1-7 years past the menopause (r = 0.52, p less than 0.01). Body mass index was less highly correlated with the rate of change of BMC in these women (r = 0.41, p less than 0.05). We conclude that urinary E2G excretion could contribute to a screening procedure for the assessment in women soon after the menopause of the risk of osteoporotic fracture in later life.

Determination of Nonconjugated and Conjugated Steroid Levels in Plasma and Prostate after Separation on C‐18 Columns

An accurate method is described for analysis of C-21, C-19, and C-18 steroids as well as steroid conjugates, namely, androstane-3 alpha,17 beta-diol glucuronide, androsterone glucuronide, estradiol glucuronide, and estrone glucuronide as well as dehydroepiandrosterone sulfate and androst-5-ene-3 beta,17 beta-diol sulfate. This technique involves an extraction step, aimed at solubilizing the nonconjugated steroids as well as the steroid sulfates and glucuronides, C-18 column chromatography, permitting the separation of nonconjugated steroids and the conjugated group followed by specific hydrolysis of the glucuronide and, finally, solvolysis of the steroid sulfates. Our data indicated that using 1 ml of plasma or 1 g of prostate, good recovery of the three groups of steroids was obtained. Moreover, an accurate determination of steroids could be achieved. The plasma levels of steroids in normal adult women and men found using our technique were within the range of those previously reported by us and other authors.

Unconjugated and Glucuronide Steroid Levels in Human Breast Cyst Fluid

The present report deals with the concentrations of C-21, C-19 and C-18 steroids as well as steroid glucuronides, namely androstane-3 alpha,17 beta-diol glucuronide, androsterone glucuronide, estradiol glucuronide, and estrone glucuronide (E1-G) in breast cyst fluid (BCF). The concentration of the gross breast cystic disease protein 15 (GCDFP-15) was also measured and its value was correlated with concentrations of unconjugated steroids as well as steroid conjugates. The present data indicate that for a large number of unconjugated steroids (namely pregnenolone, progesterone, dehydroepiandrosterone (DHEA), androsterone, androstane-3 alpha,17 beta-diol, estrone and estradiol) there is an important accumulation in BCF. Our data permit us to demonstrate a statistical relationship between the concentrations of DHEA and its metabolites (namely, androstenedione [4-ene-Dione]), thus suggesting an activity of the enzyme 3 beta-hydroxysteroid dehydrogenase-4-ene-5-ene-isomerase in the breast tissue. Further examination of the relationship between the concentrations of 4-ene-Dione and its metabolites, namely testosterone and 5 alpha-reduced steroid metabolites, as well as their glucuronide derivatives, strongly suggests that the metabolism of androgens in the breast tissue occurs mainly via 5 alpha-reductase and glucuronyl transferase activities. The concentration of GCDFP-15 in BCF found in the present investigation was 2745 +/- 234 micrograms/ml and we have shown that a negative relationship exists in the BCF between E1-G and GCDFP-15 levels.

Species comparison of steroid UDP-glucuronyl transferase: Correlation to TCDD sensitivity

Estradiol glucuronidation via steroid UDP-glucuronyl transferase (sUDPGT) was examined in 2,3,7,8-te trachlorodibenzo- p-dioxin (TCDD) sensitive and resistant species and strains. Steroid UDPGT was not induced by treatment with TCDD or estradiol. The most sensitive species to TCDD lethality, the guinea pig, had relatively high steroid UDPGT activity, while the hamster, the most resistant species, and rats had low levels of activity; no differences in sUDPGT activities were observed between mouse or rat strains differing in susceptibility to TCDD intoxication. These results suggest a role for differences in steroid physiology in the determination of species susceptibility to TCDD, but also demonstrate that other factors are involved.

Steroids and steroid glucuronides in the ovarian fluid of the African catfish,Clarias gariepinus, between ovulation and oviposition

As part of a series of experiments concerning a possible pheromonal function of steroids and steroid glucuronides excreted by the sex organs of the African catfish,Clarias gariepinus, qualitative and quantitative studies, using GCMS, were carried out to examine the presence of the steroids, that can be synthesized by the ovary during oocyte maturation and ovulation, and of the corresponding steroid glucuronides, in the fluid surrounding the eggs in the ovarian cavity shortly after ovulation.Full mass spectra were obtained of 5β-pregnane-3α,17α-diol-20-one, 5β-pregnane-3α,17α,20α-triol, 5β-pregnane-3α,6α,17α-triol-20-one, 5β-pregnane-3α,6α,17α,20β-tetrol, 5β-androstane-3α,17β-diol and 5β-androstane-3α,17β-diol-11-one. After selected ion monitoring the following steroids could be detected by the presence of at least two characteristic ions at the expected retention time: 5β-pregnane-3α, 17α,20β-triol, etiocholanolone, 5β-dihydrotestosterone, 5β-androstane-3α,11β-diol-17-one, testosterone and estradiol. After treatment with β-glucuronidase the following steroids could be determined in a similar way: 5β-pregnane-3α,17α-diol-20-one, 5β-pregnane-3α,17α,20α-triol, 5β-pregnane-3α,17α,20β-triol, 5β-pregnane-3α,6α,17α-triol-20-one, 5β-pregnane,3α,6α,17α,20β-tetrol, 5β-androstane-3α,17β-diol, etiocholanolone, 5β-dihydrotestosterone, testosterone and estradiol.The free steroids 5β-pregnane-3α,6α,17α,20β-tetrol and 5β-pregnane-3α,6α,17α-triol-20-one and the steroid glucuronides of testosterone, 5β-dihydrotestosterone and estradiol appeared to be the most abundant of these compounds. The results indicate that very polar steroids and steroid glucuronides, synthesized in the ovary, can be excreted via the ovarian fluid shortly before and during oviposition, and possibly function as sex attractants, inducing reproductive behaviour in male conspecifics.

Androgen and estrogen dynamics in the female baboon ( Papio anubis)

Androgen and estrogen dynamics were studied in 5 female baboons ( Papio anubis) using constant infusions of [ 3H]androstenedione/[ 14C]estrone and [ 3H]testosterone/[ 14C]estradiol. Blood samples were obtained prior to the infusions and both blood and plasma was used for measurements of androstenedione (A), testosterone (T), dihydrotestosterone (DHT), estrone (E 1), estradiol (E 2). Plasma was used for measurements of sex-hormone binding globulin (SHBG), and the percents of T and E 2 free, bound to SHBG, and to albumin. Blood samples obtained during the infusions were analyzed for radioactivity as purified androgens and estrogens. Metabolic clearance rates (MCR), and transfer factors ([ρ] BB; fraction of steroid infused which is converted to and measured in blood as product) and blood production rates were calculated from whole blood data. All urine was collected for 96 h and an aliquot analyzed for radioactivity as the glucuronides of estrone and estradiol and the % peripheral aromatization calculated. The MCR's, calculated in whole blood, of A, E 1, E 2 and T were 53 ± 6 I/day/kg, 39.3 ± 31/day/kg, 29.9 ± 5.21/day/kg and 10.1 ± 2.31/day/kg, respectively. Each MCR was different ( P < 0.05) from the others. The P b of E 1 was 15± 2μg/day and was not different from that of E 2 (12 ± 3 μg/day). The P B of A, 231 ± 55μg/day, was greater than that of T, 13± 5μg/day. The interconversions of both the androgens (18.9 ± 3.4% vs 3.9 ± 1.0%) and the estrogens (48.8 ± 10.7% vs 4.0 ± 0.8%) favored the oxidative pathway, i.e. conversion of 17-OH to 17-oxo steroids. The conversion ratio of A to DHT was greater than that of T to DHT (16.4 ± 2.1% vs 5.3 ± 0.7%), and A is a more important source of DHT than is T. The percent of T bound to SHBG (80.7 ± 0.9%) was greater than percent of E 2 (36.9 ± 9.8%) and inversely the percents of T bound to albumin and free (17.5 ± 0.8% and 1.65 ± 0.16%) were less than the respective percents for estradiol (60.5 ± 9.5% and 2.40 ± 0.27%). The mean SHBG concentration was 54 ± 6 nM. The peripheral aromatization of androstenedione, 1.36 ± 0.05%, was greater than of testosterone, 0.18 ± 0.02%. This difference is, in part, due to the lack of SHBG-binding of androstenedione. The general pattern of androgen and estrogen dynamics is similar to that in women. This similarity is due, in part, to the presence of SHBG in both baboons and women.

Formation of estrogen glucuronides by human granulosa-luteal cells isolated from human menopausal gonadotropin-stimulated cycles for in vitro fertilization.

The formation of steroid glucuronides by human granulosa cells isolated from human menopausal gonadotropin (hMG)/human chorionic gonadotropin (hCG)-stimulated cycles for in vitro fertilization was studied. From granulosa cells in suspension, 5 x 10(-7) M androstenedione was converted into estradiol (2.50 +/- 0.21 ng/ml), estrone (1.84 +/- 0.16 ng/ml), estradiol glucuronide (0.38 +/- 0.07 ng/ml), as well as estrone glucuronide (0.24 +/- 0.04 ng/ml). When 5 x 10(-7) M estradiol was incubated, estrone (15.5 +/- 0.9 ng/ml) and estradiol glucuronide (0.12 +/- 0.05 ng/ml) were detected in medium. Using the same preparation of granulosa cells, we have observed that androsterone could uniquely be transformed into androstane-3 alpha, 17 beta-diol (1.42 +/- 0.56 ng/ml), and only low amounts of steroid glucuronides could be detected. Since the formation of steroid glucuronides was extremely small when granulosa cells in suspension were used, we subsequently studied granulosa cells in culture. When 5 x 10(-7) M estradiol was added, estrone (7.8 +/- 1.3 ng/ml) and estradiol glucuronide (0.68 +/- 0.08 ng/ml) were formed. The addition of follicle-stimulating hormone did not cause a further increase in estrone or estradiol glucuronide levels. As observed with granulosa cells in suspension, incubation with androsterone led to the formation of androstane-3 alpha, 17 beta-diol (24.2 +/- 0.07 ng/ml). Our data demonstrated the presence of glucuronyltransferase in human granulosa cells obtained from preovulatory follicles of hMG/hCG-treated women. In addition, since the conversion of androsterone into C-19 steroid glucoronide was relatively small, the present finding also indicates that the glucoronyltransferase enzymatic activity in granulosa-luteal cells preferentially conjugated estrogens.

Inhibition of peripheral aromatization in baboons by an enzyme-activated aromatase inhibitor (MDL 18,962).

The peripheral aromatization ([rho]BM) of androstenedione (A) and testosterone (T) was measured before and after administration of the aromatase inhibitor 10-(2 propynyl)estr-4-ene-3,17-dione (MDL-18,962) to five mature female baboons, Papio annubis. The measurements were made by infusing [3H]androstenedione/[14C]estrone or [3H]testosterone/[14C]estradiol for 3.5 h and collecting blood samples during the infusions and all urine for 96 h from the start of the infusion. Blood samples were analyzed for radioactivity as infused and product steroids, and the data were used to calculate MCRs. An aliquot of the pooled urine was analyzed for the glucuronides of estrone and estradiol and used to calculate the [rho]BM. MDL-18,962 was administered as a pulse in polyethylene glycol-400 (1-5 ml) either iv or via gastric tube 30 min before administration of the radiolabeled steroids. Control studies were done with and without polyethylene glycol-400 administration. When MDL-18,962 was given iv at 4 mg/kg, the aromatization of A was decreased 91.8 +/- 0.9% from the control value of 1.23 +/- 0.13% to 0.11 +/- 0.01%. At the same dose, aromatization of T was decreased 82.0 +/- 7.1%, from a control value of 0.20 +/- 0.03% to 0.037 +/- 0.018%. When MDL-18,962 was given iv at doses of 0.4, 0.1, 0.04, and 0.01 mg/kg, the values for aromatization of A were 0.16 +/- 0.03%, 0.18 +/- 0.06%, 0.37 +/- 11%, and 0.65 +/- 0.09%, respectively. The administration of MDL-18,962 via gastric tube at 4 mg/kg as a pulse decreased the aromatization of A from 1.35 +/- 0.06% to 0.43 +/- 0.12%, an inhibition of 67.2 +/- 10.7%. When administered via gastric tube daily for 5 days at 4 mg/kg, the aromatization of A fell from 1.35 +/- 0.06% to 0.063 +/- 0.003%, an inhibition of 84.4 +/- 0.5%. The MCRs of A and estrone were not altered by any dose of MDL-18,962 regardless of the mode of administration, but there was an increase in the MCRs of T and estradiol at the only dose (4 mg/kg, iv) at which these steroids were infused. The interconversions between the androgens and between the estrogens were not altered by the administration of MDL-18,962 at 4 mg/kg, iv. The enzyme-activated inhibitor MDL-18,962 is an effective inhibitor of [rho BM] in female baboons and could prove to be a useful therapeutic agent in treating estrogen-dependent breast cancer.

Characterization of antibodies to a rabbit hepatic UDP-glucuronosyltransferase and the identification of an immunologically similar enzyme in human liver

An antibody to a UDP-glucuronosyltransferase (UDPGT) isoenzyme which catalyzes the glucuronidation of p-nitrophenol (PNP) in rabbit liver was raised in sheep and used to identify immunologically similar UDPGTs in rabbit and human livers. Immunoblotting experiments showed that the antisera specifically recognized PNP UDPGT but not estrone UDPGT purified from rabbit liver. Sheep anti-rabbit liver PNP UDPGT IgG immunoprecipitated PNP, 1-naphthol, and 4-methylumbelliferone glucuronidation activities in rabbit and human liver microsomal preparations. In rabbit liver microsomes the antibody did not immunoprecipitate estrone or estradiol glucuronidation activities. In human liver microsomes, 4-aminobiphenyl but not estriol glucuronidation activities were immunoprecipitated, suggesting that the antibody recognizes a specific UDPGT (p I 6.2) in human liver microsomes.

The effects of l-thyroxine and dexamethasone on steroid dynamics in male cynomologous monkeys

Male cynomologous monkeys ( M. fascicularis) were infused with [ 3H]androgens, [ 14C]estrogens and [ 3H]cortisol before and after the administration of l-thyroxine, ( l-T 4) 150 μg/day for 6 wk, dexamethasone 8 mg every 8 h for 3 doses and dexamethasone 1.0 mg/day for 8 days. Blood samples were obtained before each of the infusions and analyzed for endogenous T, A, E 1, E 2 and F concentrations, % free T and % free E 2, sex hormone-binding globulin (SHBG) and cortisol binding globulin (CBG) capacity. When l-T 4 was being administered, T 4 and triiodothyronine (T 3) concentrations were also measured. Blood samples were obtained during the infusions and analyzed for radioactivity as testosterone (T), androstenedione (A), dihydrotestosterone (DHT), estradiol (E 1), estrone (E 2), and cortisol (F). All urine was collected for 96 h and an aliquot of the pooled urine was analyzed for radioactivity as estrone and estradiol glucuronide. The administration of l-T 4 for 6 wk to 3 monkeys resulted in a marked rise in T 4 and T 3 levels, from 4.8 ± 0.4 μg/dl to 24.8 ± 0.8 μg/dl and from 136 ± 6 to 515 ± 71 ng/dl, respectively. MCR T, MCR E 2 and MCR E 1 did not change, but MCR A values increased slightly and MCR F increased 2–3-fold. [ϱ] T,E 2 did not change but [ϱ] BM A,E 1 showed a slight but significant increase. The inter-conversions between the androgens and between the estrogens were not altered. There was a 2–3-fold increase in SHBG and a decrease in %FT but no change in %FE 2 or CBG. The concentrations of T, A and DHT rose but there was no trend in the levels of the estrogens. The administration of dexamethasone 8 mg every 8 h for 3 doses or 1 mg/day for 8 days caused no changes in the MCRs for T, A, E 1 and E 2 but did not cause a significant decrease in MCR F. Measurement of splanchnic and peripheral tissue extractions before and after acute dexamethasone administration in 1 monkey showed that the decrease in MCR F was the result of a marked decrease, 11-2%, in splanchnic extraction of F. The extractions of T and E 2 were relatively unaffected. The concentrations of T and F fell but E 2 remained the same. % FT and % FE 2 rose slightly and the concentrations of SHBG and CBG were unchanged. The androgen interconversions and estrogen interconversions were not affected but [ϱ] BM T,E 2 and [ϱ] BM A,E 1 showed slight decreases. The changes in steroid dynamics as a result of l-T 4 are caused in part by increases in SHBG and tissue blood flow which for T and E 2 act as opposing forces to maintain their dynamics relatively normal, but for A, E 1 and especially F the effects of increases in tissue blood flow are dominat. Dexamethasone, acutely and chronically, decreases T and F concentration, but only MCR F is decreased. The decrease in MCR F is associated with a marked decrease in the hepatic extractions of F. Peripheral aromatization is decreased by both treatments, but more so by the longer treatment.

Effects of ethanol on the levels of unconjugated and conjugated androgens and estrogens in plasma of men

The concentrations in plasma of estradiol, estrone, testosterone and 4-androstene-3,17-dione and their monosulphates and glucuronides were determined after oral administration of 0.3 g ethanol per kg body weight to four men. The levels of the unconjugated steroids did not change in a consistent way. In contrast, the concentrations of estradiol monosulphate and estradiol glucuronide increased markedly. The increase paralleled the blood alcohol concentrations and control levels were reached 3 h after the ethanol intake. A coupling of ethanol oxidation with reduction of dehydroepiandrosterone sulphate has previously been established, and it is suggested that the ethanol-induced change of the hepatic redox level affects the interconversion of conjugated forms of estradiol and estrone resulting in elevated levels of conjugated estradiol. This could have a feminizing effect and affect the feed-back regulation of gonadal hormone production.

The metabolism of estradiol; oral compared to intravenous administration

We administered [6,7- 3H]estradiol p.o. and [4- 14C]estradiol i.v. simultaneously to 5 women 22–35 years of age. Fourteen blood samples were collected over 480 min, and all urine was collected for 96 h. The blood samples were analyzed for radioactivity as estradiol, estrone, estrone-sulfate and estradiol glucuronide. The urine samples were analyzed for radioactivity as the glucuronide and pH 1 hydrolyzable conjugates of estradiol, estrone, estriol, 16α-hydroxy-estrone, 2-hydroxy-estrone, 2-hydroxy-estradiol, 2-methoxy-estradiol and 2-methoxy-estrone. The major circulating estrogen, after either estradiol, p.o. or i.v. administration, was estrone sulfate; ~ 50% of estradiol administered by either route being converted to and measured as estrone sulfate in the blood. Following oral administration about twice as much estradiol was converted to and measured as estradiol glucuronide in the blood as after i.v. administration. Of the estradiol administered p.o., only 10% was absorbed into the blood as estradiol the rest being metabolized prior to absorption. After estradiol, p.o., the major radioactive compounds in the urine were the glucuronides of estrone and estradiol, but after estradiol, i.v., the conjugates of estrone, estradiol and estriol were present to about the same extent as the conjugates of the 2-oxygenated compounds. Following p.o., considerable metabolism of estradiol administration occurs in the splanchnic tissue, much of it in the intestinal wall.

Hormonal changes during induced ovulation of the carp, Cyprinus carpio

The changes in plasma concentrations of eight steroids (testosterone, testosterone glucuronide, estradiol, estradiol glucuronide, 17-hydroxyprogesterone, 17,20β-dihydroxy-4-pregnen-3-one (17,20βP), deoxycorticosterone, and cortisol) have been followed in three individual carp, Cyprinus carpio, during ovulation induced by carp pituitary extract. Deoxycorticosterone and estradiol glucuronide were not detectable and small amounts of 17,20βP were found only in one fish. A priming injection of pituitary extract, administered 24 hr before ovulation, stimulated an increase in testosterone 3–6 hr later, followed by an increase in estradiol. The second injection of pituitary extract given 12 hr after the priming dose, resulted in a second peak of testosterone which was accompanied by a peak of testosterone glucuronide, a conjugate which was usually formed in only small amounts following the priming dose. A sharp peak of 17-hydroxyprogesterone followed the second stimulation and it is suggested that this, rather than 17,20βP, may be the natural inducer of maturation in carp. Although cortisol levels showed large variations, they appeared to be stimulated by the priming dose of pituitary extract. Levels of all steroids, except for cortisol, fell rapidly after ovulation.

Effect of taurocholate (TC) or dehydrocholate (DHC) in the reversal of estradiol-17β-glucuronide (E-17G) cholestasis in the isolated perfused rat liver (IPRL)

Effect of taurocholate (TC) or dehydrocholate (DHC) in the reversal of estradiol-17β-glucuronide (E-17G) cholestasis in the isolated perfused rat liver (IPRL)

Steroid D-ring glucuronides: a new class of cholestatic agents

The inhibitory effects of estrogens on hepatic exretory function are well known. Recent studies suggest that these efects may be mediated by certain estrogen metabolites, the D-ring glucuronide conjugates. Although glucuronide onide conjugates have long been thought to be non-toxic end product of drug metabolism, Mary Vore and William Slikker discuss the evidence thatthe potent cholestatic activity of the D-ring glucuronides of estradiol, estriol and ethynylestradiol in animal models indicates that this metabolic pathway may be responsible for some of the hepatic toxicities seen in pregnancy and with oral contraceptive use.