Higher Estradiol Concentrations Research Articles

Influence of follicular atresia on LH-induced cAMP and steroid synthesis by bovine thecae interna

The aim of the present study was to examine the interrelationships between the luteinizing hormone (LH) receptor, the LH-induced changes in adenosine cyclic 3', 5'-monophosphate (cAMP) and steroid synthesis in theca interna tissue of large antral follicles (> 8 mm diameter) from oestrous cycling cows. Three distinct types of theca interna were identified (types I, II and III), all of which contained an LH receptor: type I was capable of secreting increased amounts of cAMP dehydroepiandrosterone, androstenedione and testosterone when exposed to LH; type II was capable of secreting increased amounts of cAMP and progesterone but not the androgens when exposed to LH; type III was incapable of cAMP or steroid synthesis when exposed to LH. Follicles with type I thecae contained: (a) a full complement of granulosa cells; (b) high intrafollicular concentrations of oestradiol; and (c) granulosa cells with a high capacity to metabolise testosterone to oestradiol. These follicles were considered to be non-atretic structures. Follicles with types III thecae contained: (a) fewer granulosa cells; (b) low intrafollicular concentrations of oestradiol; and (c) granulosa cells with a low capacity to metabolise testosterone to oestradiol. Moreover, follicles with type III thecae contained the highest concentrations of progesterone and the lowest concentrations of androstenedione and testosterone. These follicles were considered to be severely atretic structures. Follicles with type II thecae contained granulosa cell populations and progesterone, and androgen concentrations which were intermediate between those with thecae of types I and III. These follicles were considered to be at an intermediate stage of atresia. Collectively the data suggest that during follicular atresia the LH receptor characteristics in theca interna remain unchanged while the tissue first loses its capacity to respond to LH to synthesize androgens and then loses its ability to respond to LH to synthesize cAMP.

Estrogen and progesterone receptor and hormone levels in human myometrium and placenta in term pregnancy

Estradiol and progesterone receptors in the myometrium, decidua, placenta, chorion, and amnion of eight women who underwent elective cesarean section at term were determined by means of an exchange assay. The hormone levels in the peripheral plasma and cytosol of these tissues were measured by radioimmunoassays. Maternal plasma and the placenta had high concentrations of estradiol and progesterone, with the placenta having 12 times more progesterone than in maternal plasma but only half the concentrations of estradiol in maternal plasma. The decidua and placenta had detectable levels of cytosol and nuclear estradiol receptors, but the myometrium had no measurable cytosol estradiol receptors, whereas the chorion and amnion had neither cytosol nor nuclear estradiol receptors. However, the chorion and amnion had significantly higher concentrations of estradiol in the cytosol than those in the decidua and myometrium. Only the decidua and myometrium had cytosol and nuclear progesterone receptors, but the placenta, amnion, and chorion had neither cytosol nor nuclear progesterone receptors. In contrast, progesterone hormone levels were significantly higher in the placenta, amnion, and chorion than in the decidua and myometrium. The findings indicate that, in the term pregnant uterus, (1) the placenta, amnion, and chorion are rich in progesterone, estradiol, and nuclear estradiol receptors but have no progesterone receptors, (2) the decidua and myometrium have nuclear estradiol and progesterone receptors, and (3) the myometrium has a higher progesterone/estradiol ratio than that of the peripheral plasma, thus suggesting a highly progesterone-dominated uterus.

The endogenous concentration of estradiol and estrone in normal human postmenopausal endometrium

The endogenous estrone (E 1) and estradiol (E 2) levels (pg/g tissue) were measured in 54 postmenopausal, atrophic endometria and compared with the E 1 and E 2 levels in plasma (pg/ml). The results from the tissue levels of both steroids showed large variations and there was no significant correlation with their plasma levels. The mean E 2 concentration in tissue was 420 pg/g, 50 times higher than in plasma and the E 1 concentration of 270 pg/g was 9 times higher. The E 2/E 1 ratio in tissue of 1.6, was higher than the corresponding E 2/E 1 ratio in plasma, being 0.3. We conclude that normal postmenopausal atrophic endometria contain relatively high concentrations of estradiol and somewhat lower estrone levels. These tissue levels do not lead to histological effects.

The antiproliferative effect of tamoxifen in breast cancer cells: mediation by the estrogen receptor

The effects of tamoxifen (Tam) and its 4-hydroxylated metabolite (OH-Tam) on the growth of two human breast cancer cell lines (MCF7 and BT20) were evaluated by fluorometric DNA assay. The effects of the antiestrogens were dependent upon their concentrations and the nature of the cells. At concentrations below 4 μM, the degree of inhibition was related to their relative affinities for the estrogen receptor and was totally reversed by estradiol in MCF7 cells. No inhibition was observed in the estrogen receptor negative cell line BT20. This supports and extends the idea that the antiproliferative effect of Tam at these concentrations is mediated by the estrogen receptor even in the absence of measurable estradiol concentration. At concentrations greater than 4 μM, Tam was cytotoxic on MCF 7 and BT20 mammary cell lines within 2 days of treatment. The cytotoxic effect was irreversible and was not prevented by occupation of the estrogen receptor with estradiol, suggesting that it was not mediated by the estrogen receptor. The cytotoxicity of the triphenylethylene drugs, however, has some specificity since it was not observed in a fibroblast rat cell line (49F) or in the two mammary cell lines with similar high concentrations of estradiol and diethylstilbestrol.

Estradiol and progesterone receptors in gynecologic sarcomas.

We report the concentrations of estradiol and progesterone receptors found in the tumor tissue of 5 patients with leiomyosarcoma, 4 of uterine and one of ventricular origin, and of 5 patients with uterine or ovarian carcinosarcoma. Steroid receptor positive and negative tumors were present in both groups of sarcoma. One uterine leiomyosarcoma had a high concentration of estradiol and progesterone receptors, 37 fmoles/mg protein and 156 fmoles/mg protein, respectively. We suggest that steroid receptors should be analysed in all gynecologic sarcomas.

Distinguishing the steroidogenic roles of granulosa and theca cells of the dominant ovarian follicle and corpus luteum.

In order to determine the relative contribution of granulosa cells and follicular fluid of the preovulatory follicle to ovarian and peripheral vein levels of principal steroids in the late follicular phase, as well as the importance of granulosa cells and theca cells in subsequent corpus luteum function, 32 rhesus and cynomolgus monkeys were studied. In group one (n = 10), they were bled from the femoral vein daily throughout the cycle and sera assayed for FSH, LH, estradiol, and progesterone. In addition, they were laparotomized in the late follicular phase when serum estradiol (by rapid assay) had exceeded 150 pg/ml for about 24 h. Ovarian vein blood was taken ipsilateral to the dominant follicle, followed by aspiration of follicular contents and rinsing of the antrum to remove as many granulosa cells as possible without disturbing the thecal layers. Also, blood from the contralateral ovarian vein was obtained, as well as a second collection from the ipsilateral ovarian vein 15 min after follicular aspiration; a second peripheral sample was obtained immediately thereafter. Ovarian vein asymmetry of estradiol, progesterone, and androstenedione, but not 17-OH progesterone, was noted in every case (i.e. higher steroid levels were associated with the putative dominant follicle). After follicular aspiration, high concentrations of estradiol, progesterone, and androstenedione in ovarian venous effluent fell (P less than 0.001) by nearly 70% from preaspiration levels; concurrently, peripheral levels of estradiol and progesterone were reduced by about 40%. Conversely, 17-OH progesterone was unaffected. Integrated progesterone levels throughout the subsequent luteal phase, but not serum estradiol, were significantly (P less than 0.001) less in the experimental monkeys (after aspirating/rinsing) compared to controls, although luteal phase length was unchanged (14.33 vs. 14.83 days). Groups two (n = 7) and three (n = 15) were employed to assess the influence of vascular trauma caused by either continuous cannulation or serial (up to six insults) venipuncture, on the concentrations of the principal ovarian steroids in ovarian vein blood.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of combination chemotherapy on ovarian function in women treated for Hodgkin's disease.

Ovarian function has been studied in 44 adult females who previously received quadruple chemotherapy (MVPP) for Hodgkin's disease. The median age at treatment was 23 years, and the length of time between completion of treatment and study ranged from 6 months to 10 years (median, 30 months). Seventeen women maintained regular menses, 10 developed oligomenorrhea, and 17 developed amenorrhea. At treatment, the 17 women who subsequently developed amenorrhea were significantly older (median, 30 years) than those who maintained regular menses (median, 22 years) or developed oligomenorrhea (median, 23 years). All patients older than 36 years at the start of treatment stopped menstruating during chemotherapy. The cause of the menstrual disturbance in these patients was chemotherapy-induced ovarian damage characterized by high serum gonadotrophin and low serum estradiol concentrations. After completion of treatment there were 17 pregnancies, which resulted in 9 normal infants, 3 terminations, and 4 spontaneous abortions. Nine patients took the combination oral contraceptive pill throughout chemotherapy; however, subsequently 4 developed amenorrhea and 3 oligomenorrhea, suggesting that these patients had not been protected from chemotherapy-induced ovarian damage. Estrogen replacement therapy was of definite benefit in the symptomatic patients with premature ovarian failure.

High Fetal Estrogen Concentrations: Correlation with Increased Adult Sexual Activity and Decreased Aggression in Male Mice

In the house mouse (Mus musculus), fetuses may develop in utero next to siblings of the same or opposite sex. The amniotic fluid of the female fetuses contains higher concentrations of estradiol than that of male fetuses. Male fetuses that developed in utero between female fetuses had higher concentrations of estradiol in their amniotic fluid than males that were located between other male fetuses during intrauterine development. They were also more sexually active as adults, less aggressive, and had smaller seminal vesicles than males that had developed between other male fetuses in utero. These findings raise the possibility that during fetal life circulating estrogens may interact with circulating androgens both in regulating the development of sex differences between males and females and in producing variation in phenotype among males and among females.

Development of nonovulatory antral follicles in heifers: changes in steroids in follicular fluid and receptors for gonadotropins.

The objective of this study was to examine changes in steroid concentrations in follicular fluid (FF) and in gonadotropin receptors in nonovulatory follicles that develop after ovulation in heifers. Six groups of six to seven heifers were ovariectomized on days 3, 5, 7, 9, 11, and 13 of an estrous cycle. Follicles 6 mm or more in diameter were separated into two classes, estrogen-active (E-A) and estrogen-inactive (E-I). E-A follicles had higher concentrations of estradiol than progesterone and androgens in FF and a low incidence of atresia. E-I follicles had higher concentrations of progesterone or androgens than estradiol in FF and a high incidence of atresia. Diameters, numbers of granulosa cells, and capacities of granulosa cells and thecal tissue to bind [125I]iodo-hCG increased in E-A follicles from days 3-7. During this time, diameters, numbers of granulosa cells, concentrations of estradiol, and capacities of granulosa cells and thecal tissue to bind gonadotropins were greater in E-A than E-I follicles. On days 9, 11, and 13, each heifer had only a single E-I follicle. Compared with E-A follicles on day 7, E-I follicles on days 9, 11, and 13 were smaller and had less granulosa cells, less estradiol in FF, and a lower capacity to bind [125I]iodo-hCG. After day 7, E-A follicles were not observed until day 13. We conclude that at least two periods of growth and atresia of follicles occur between days 3-13 of an estrous cycle in heifers. One is during days 3-7 when a single E-A follicle 6 mm or more in diameter develops and all other E-I follicles regress. The other is between days 7 and 13 when the E-A follicle from day 7 becomes an E-I follicle and regresses, and another E-A follicle develops.

Development of antral follicles in cattle after prostaglandin-induced luteolysis: changes in serum hormones, steroids in follicular fluid, and gonadotropin receptors.

Changes in growth, concentrations of steroids in follicular fluid, and numbers of gonadotropin receptors in follicles 6 mm or more in diameter were examined 12, 24, 36, 48, 60, and 72 h after prostaglandin (PG)-induced luteolysis in heifers. Follicles with higher concentrations of estradiol than progesterone and androgens in follicular fluid (FF) were classified as estrogen active (E-A). Follicles with higher concentrations of progesterone or androgens than estradiol in follicular fluid were classified as estrogen inactive (E-I). Although E-A and E-I follicles were similar in size 12-72 h after PG treatment, before the preovulatory surge of LH, numbers of granulosa cells, estradiol concentrations, and capacities of follicles to specifically bind gonadotropins were markedly lower in E-I follicles. Most E-I follicles had histological signs of atresia, whereas E-A follicles did not. Sizes, concentrations of steroids in FF, and specific binding of gonadotropins to follicle cells did not change in E-A or E-I follicles 12-72 h after PG treatment but before the preovulatory surge of LH. However, diameters of E-A follicles were highly correlated with concentrations of estradiol and progesterone in FF and with capacities of granulosa and thecal cells to specifically bind [125I] iodo-hCG. In contrast, diameters of E-A follicles were highly negatively correlated with concentrations of testosterone in FF and with capacities of granulosa cells to specifically bind [125I] iodobovine FSH. We conclude that E-I follicles are atretic and E-A follicles are potentially ovulatory follicles. In addition, after a single injection of PG during an estrous cycle in heifers, the growth the differentiation of ovulatory follicles were not synchronized.

Effects of oestradiol on sex hormone binding globulin.

Sex hormone binding globulin (SHBG) levels were studied for possible effects of oestradiol-17 beta on SHBG. No change in SHBG plasma was recorded during normal menstrual cycles or during treatment with oestradiol-17 beta to menopausal women. However, gonadotrophin treatment to amenorrhoeic women to induce ovulation resulted in high oestradiol concentrations and a pronounced increase in SHBG was found during the luteal phase of these cycles. A marked increase of SHBG was also recorded in a woman with pronounced fluctuations of oestradiol during treatment with levonorgestrel sc implants for contraception. In conclusion, effects on SHBG were only found when extraordinarily high levels of plasma oestradiol were recorded.

Regulation of ovarian follicular and luteal function during treatment with exogenous gonadotropins in anovulatory infertility

The dosage, duration of treatment, and plasma hormone levels were analyzed statistically between and within groups of treatment cycles with (n = 46) and without (n = 10) ovulation. A significant difference was observed in the dosage of human menopausal gonadotropins (hMG) over various days of treatment, but not in the mean dosage of hMG and human chorionic gonadotropin (hCG) administered per cycle. Follicle-stimulating hormone (FSH):luteinizing hormone (LH) ratios, prolactin (PRL) levels, and the magnitude and the duration of the estradiol response were greater in the ovulatory cycles. Additionally, in the ovulatory cycles, the dose of hMG correlated with the plasma levels of estradiol, FSH, and LH, while in the anovulatory cycles, hMG dosage correlated only with the LH concentrations. After administration of hCG, the mean plasma concentrations of its beta subunit peaked within 1 day and remained detectable for up to 10 days thereafter. In the ovulatory cycles, the mean progesterone level was maximal 6 days following hCG administration. In these cycles, luteal phase progesterone levels correlated positively with the preovulatory estradiol and inversely with concentrations of the beta subunit of hCG. The data demonstrate that, in contrast to anovulatory follicles, ovulatory follicles were exposed to a relative “dominance” of FSH over LH, with higher concentrations of estradiol and PRL for several days before hCG was administered. Apart from hMG dosage, the endogenous discharge of LH appeared to be an important determinant of the ovarian response. A single 10,000 IU dose of hCG was adequate for inducing ovulation and maintaining luteal function.

Uterine estrogen receptor assayed by the controlled pore glass (CPG) method in adult rat after steroid administration.

The interaction of estrogen and androgen was studied at the estrogen receptor level of adult rat uterus by the in vivo experiment. Both the free and total estrogen receptor in the cytosol and nucleus were assayed by the controlled pore glass beads method [2]. Testosterone was given by daily injection for 5 days to the rats treated with estradiol dipropionate (long-acting estradiol) 3 or 5 days before. In the estradiol dipropionate-treated rats the plasma estradiol concentration remained at an extremely high level for 7 days and then decreased to 5-fold of that of proestrus control by the 14th day. There was no significant change in the uterine estrogen receptor of the adult rat with a high estradiol concentration induced by testosterone.

An oestrone-releasing vaginal ring in the treatment of climacteric women

Post-menopausal patients were treated with a new form of oestrogen administration by using two types of oestrone-containing vaginal rings. It was observed that oestrone was absorbed from the vagina as demonstrated by elevated plasma concentrations of oestrone (E 1) and oestradiol (E 2). In 3 out of 4 patients the ratio of E 1/E 2 was 4–5 in the first plasma samples collected after the initiation of the treatment. After the first week of treatment this ratio had dropped to 0.8–1.5, which indicates an increase and stabilization in the conversion of oestrone to oestradiol within 1 wk of treatment. The high levels of plasma oestrogens were associated with a decrease of plasma gonadotrophins and the disappearance of climacteric symptoms. The first type of ring tested resulted in a high initial burst of oestrone release, as evidenced by high concentrations of oestrone and oestradiol during the first 2 wk. In the second type of vaginal ring the high initial oestrone release was not present and the plasma oestrone and oestradiol levels were stable. The patients tolerated the treatment well, and after gaining experience, easily accepted this route of self-administration. It seems that the vaginal silastic ring is an effective steroid-delivery system in post-menopausal women. As judged by plasma oestrone and oestradiol profiles, it seems that the second type of ring was preferable to the first one as an intravaginal releasing device.

Effect of an intra-uterine device on intracellular relationships of the uterine oestrogen receptor, particularly during pregnancy.

The presence of an intra-uterine device in the rat results in a lower nuclear concentration of the oestrogen receptor in the treated horn at pro-oestrus when it is compared with the contralateral control horn. This effect was also seen after the administration of hyperphysiological doses of oestradiol and when the horn was exposed in vitro to high concentrations of oestradiol. The cyclic changes during the oestrous cycle in the activity of the oestrogen-induced enzyme peroxidase were similar in the treated and control horns. These observations have discounted the possibility that the relatively lower nuclear receptor content in the treated horn at pro-oestrus was due to a decreased exposure to oestrogen. A significantly lower nuclear content was also observed in the treated horn on days 4 and 5 of pregnancy. This was not associated with a deficiency in cytosol receptor content which increased concurrently with that of the control horn in the 6 days of pregnancy that were studied. The proportional content of the putative cytosol factor implicated in receptor translocation was similar in both horns, increasing on days 4 and 6 in concert with reported changes in 'induced protein' synthesis. There appeared to be reduced levels of nuclear receptor at a time when blastocyst implantation normally occurs.

HORMONAL EFFECTS ON RAT MAMMARY GLAND IN VITRO

The mammogenic and lactogenic effect of various hormones on rat mammary gland has been studied in vitro using an organ culture technique. The effects have been assessed mainly by light microscopy. The study has been confined mainly to the effects and interactions of the lactogenic protein hormones, corticosteroids and progesterone. It establishes the importance of the presence of insulin and serum and of the type of serum for the hormonal effects in vitro. These effects have been studied mainly on the explants obtained from 13 days pregnant rats. In addition explants from non-pregnant rats and at various stages of pregnancy and lactation were studied.

Effect of endometrial damage and prostaglandin F2α on experimental cystic ovarian follicles in the cow

Injection of increasing doses of testosterone during the follicular phase of the oestrous cycle resulted in the cystic ovarian condition in experimental cows. Peak concentrations of oestradiol in daily plasma samples varied between 25 and 35 pg/ml, although values as low as 6 pg/ml were noted. Progesterone values were generally less than 2 ng/ml. The appearance of the endometrium was characteristic of cows with high oestradiol concentrations. By scanning electron microscopy (SEM) the luminal surface was uneven and oedeniatous with numerous cilia and microvilli present. Both SEM and light microscopy (LM) revealed dilated uterine gland openings filled with secretory products. As previously reported, the induced cyst underwent spontaneous atresia between days 13 and 17 in the presence of a healthy uterus. In four instances, damage to the endometrium by intrauterine injection of Lugol’s iodine solution or of a culture of Escherichia coli organisms resulted in persistence of the cystic follicle. By SEM, exfoliated epithelial cells, inflammatory cells and fibrin with areas of necrosis were seen. Necrosis was also observed by LM and uterine glands were distorted and contained inflammatory exudate. After cessation of iodine injection or following antibiotic treatment, endometrial repair occurred shown by regenerating epithelial cells with cilia and microvilli. During this repair the persistent cysts underwent atresia, accompanied by a marked decline in oestradiol values. Cystic atresia was observed in six instances after intrauterine injection on two successive days with 6 mg of prostaglandin F2α (PGF2α during endometrial damage with iodine solution. In the first two instances, cyclic ovarian activity did not resume during the 30 day post-treatment period. An intramuscular injection of progesterone was therefore given at the time of PGF2α treatment in an attempt to facilitate a return in ovarian activity. When 1 g of depot progesterone was injected, values of 2 ng/ml in plasma for up to 10 days were achieved but with no return in ovarian activity after cystic atresia. In contrast, injection of 1 g of progesterone in oil resulted in a brief peak of 5 to 6 ng/ml in plasma progesterone values and new follicular growth with ovulation occurred within 10 days of cystic atresia. Similarly, when progesterone in oil was administered with PGF2α to three cows with spontaneously occurring cystic follicles, cystic atresia was followed by new follicular growth and ovulation.

ESTROGEN EFFECT ON CALCIUM UPTAKE BY BONE

Cord blood plasma has high concentrations of estrone (E1), estradiol (E2) and estriol (E3). E2 causes hypocalcemia in newborn rats and in parathyroidectomized (PTX) adults. Since kidney and intestine have been excluded as sites of this action, bone is the presumptive locus of calcium (Ca) sequestration. Uniform discs from the calvaria of newborn rats and young mice were incubated in Krebs' solution. The addition of E2 to the medium or prior E2 injection of the donors increased Ca uptake by 60-100%. Nitromiphene, a competitive blocker of estradiol, prevented this effect and eliminated hypocalcemia after E2 in vivo. Discs from donors injected with parathyroid extract (PTE) showed decreased Ca uptake; when both PTE and E2 were given, uptake equalled that of uninjected controls. Since E2 lowers Ca in PTX rats. Its effect on bone must be independent of, as well as opposite to, that of parathyroid hormone. E1, thought to be active only after hepatic conversion to E2, caused hypocalcemia in vivo but not in vitro. E3 was inert both in vivo and in vitro. These findings suggest that the high plasma estrogen concentrations present in the neonate may contribute to hypocalcemia through a direct effect on bone.

Relationship between the endocrine environment within the Graafian follicle and the subsequent rate of progesterone secretion by human granulosa cells in vitro.

The steroidogenic potential of granulosa cells harvested from human Graafian follicles containing varying concentrations of pituitary and steroid hormones was examined. The mitotic activity and production of progesterone by granulosa cells in vitro was found to be correlated with their hormonal environment at the time of harvesting. Only cells from follicles containing some FSH and high concentrations of oestradiol underwent spontaneous mitosis in vitro. However, mitosis could be induced by adding FSH and high concentrations of oestradiol to the culture, provided that the concentration of LH was low. Cells harvested from follicles containing LH, FSH and high concentrations of oestradiol secreted significantly more progesterone than cells from follicles which did not contain all three hormones. It is suggested that after the initiation of follicular development by FSH, a long period of exposure (8-10 Days) to both FSH and oestradiol is necessary before the maximum biosynthetic capacity of granulosa cells is achieved; this synthetic potential is then only realized under the influence of LH and prolactin. Premature exposure to LH inhibits both the mitotic activity and the steroidogenic potential of these cells.

Concentration of oestrone and oestradiol in follicular fluid and ovarian venous blood of women.

The concentrations of oestrone and oestradiol as measured by a double isotope derivative method in fluid from Graafian follicles at different phases of the menstrual cycle were compared to the corresponding concentrations in ovarian and peripheral venous plasma collected simultaneously. In follicular fluid the concentration of oestradiol was much greater than that of oestrone. The concentrations of oestrogens were similar in fluid collected from small follicles at all phases of the cycle. The concentration of oestradiol in large follicles (greater than 1 cm diameter) was much higher in the mid-late follicular phase of the cycle (mean = 5390 plus or minus 1330 nmol/l) than in large or small follicles at other phases of the cycle. In the mid-late follicular phase of the cycle large follicles were invariably associated with high concentrations of oestradiol in venous plasma draining the corresponding ovary (mean 49 plus or minus 12 nmol/l). The mean ratio of oestradiol/oestrone in fluid from large follicles in which the concentration of oestradiol was greater than 1400 nmol/l (18.0 plus or minus 1.0, n = 10) was significantly higher than the ratio in corresponding samples of ovarian venous plasma (10.7 plus or minus 1.4, n = 11). These findings suggest that when the concentration of oestradiol in a Graafian follicle exceeds 3500 nmol/l it is likely to be functionally active.