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PubMed1994

An alpha 1 adrenergic mechanism mediates estradiol stimulation of LHRH mRNA synthesis and estradiol inhibition of POMC mRNA synthesis in the hypothalamus of the prepubertal female rat.

We showed previously that the surge of luteinizing hormone-releasing hormone (LHRH) induced by estradiol-17 beta (E2) in the female rat can be blocked by an alpha 1 adrenergic antagonist. The aim of the present study was to determine whether this was due to a direct action of E2 on noradrenergic projections to LHRH neurons or whether it also involved other systems such as the arcuate pro-opiomelanocortin (POMC) neurons which are thought to inhibit LHRH biosynthesis and release. The experimental preparation was the prepubertal female rat in which an LHRH surge is induced by pregnant mare serum gonadotropin. Prazosin was used as a specific alpha 1 adrenergic antagonist and LHRH and POMC mRNA concentrations and cell numbers, in the medial preoptic area and rostral arcuate nucleus, respectively, were determined by in situ hybridization. Prazosin significantly reduced the total number of LHRH mRNA expressing cells, and increased the total number of POMC mRNA expressing cells and the concentration of POMC mRNA per cell. These results suggest that the inhibition of E2-stimulated LHRH biosynthesis and release by alpha 1 adrenergic blockade may be mediated by two mechanisms; (i) increased POMC synthesis leading to inhibition of LHRH neurons and (ii) direct inhibition of a stimulatory alpha 1 adrenergic/LHRH mechanism.

Animals↗
PubMed2001

Open, multicenter comparison of efficacy, cycle control, and tolerability of a 23-day oral contraceptive regimen with 20 microg ethinyl estradiol and 75 microg gestodene and a 21-day regimen with 20 microg ethinyl estradiol and 150 microg desogestrel.

This prospective, open, randomized study was conducted to compare the contraceptive reliability, cycle control, and tolerability of a 23-day regimen with 20 microg ethinyl estradiol (EE) and 75 microg gestodene (GSD) and a 21-day regimen with 20 microg EE and 150 microg desogestrel (DSG). Participants took either 23 tablets with active substances plus 5 placebo tablets (23-day EE/GSD) or 21 tablets with active substances followed by 7 days without pill-taking (21-day EE/DSG). Contraceptive efficacy, cycle control, and tolerability were evaluated over a period of seven cycles. Efficacy data gathered from 5967 treatment cycles (23-day EE/GSD: 2975 cycles; 21-day EE/DSG: 2992 cycles) were obtained from 890 participants (445 in each group). Both preparations proved to be effective contraceptives and provided good cycle control. No pregnancy during treatment was recorded. This resulted in a study Pearl Index of 0.0 for both treatments. For 23-day EE/GSD, 32.4% of participants reported at least one intracyclic bleeding episode during Cycles 2-4 (primary target) compared to 31.5% for 21-day EE/DSG. In the 23-day EE/GSD group, intracyclic bleeding episodes were reported by 48.8% of the participants in Cycle 1 but in only 15.1% in Cycle 7, and in the 21-day regimen group by 43.4% in Cycle 1 and only 14.2% in Cycle 7. Overall, intracyclic bleeding was reported in 20.9% of cycles for both treatments.A greater number of 23-day EE/GSD participants had shorter withdrawal bleeding periods than with 21-day EE/DSG. In significantly (p <0.0001) more cycles in the 23-day EE/GSD group participants reported withdrawal bleeding periods that lasted only 1-4 days compared to the 21-day EE/DSG group. For the majority of the treatment cycles, the median number of bleeding days in the 23-day EE/GSD group was 4 days and in the 21-day EE/DSG group 5 days. Both preparations were well tolerated and showed a similar adverse events pattern. The discontinuation rate because of adverse events was low (23-day EE/GSD: 6.1%; 21-day EE/DSG: 5.6%). No serious vascular adverse events were reported. More than 82% in the 23-day EE/GSD group and 79% in the 21-day EE/DSG group either lost more than 2 kg of weight or did not gain weight during the study. The treatment effect on blood pressure was negligible. There were no appreciable changes in mean laboratory values over the course of the study compared to baseline.

Adolescent↗
PubMed1999

Clinical comparison of triphasic norgestimate/35 micrograms ethinyl estradiol and monophasic norethindrone acetate/20 micrograms ethinyl estradiol. Cycle control, lipid effects, and user satisfaction.

This six-cycle, multicenter, open-label, randomized study compared the clinical experience of two low-dose oral contraceptives (OC): a triphasic OC containing norgestimate (NGM) and 35 micrograms ethinyl estradiol (EE) (Ortho Tri-Cyclen) and a monophasic OC containing norethindrone acetate (NETA) and 20 micrograms EE (Loestrin Fe 1/20). Cycle control, lipid and androgen profiles, and user satisfaction were studied in new-start OC users (i.e., no prior use within 60 days). Breakthrough bleeding or breakthrough spotting (BTB/BTS) occurred in a significantly smaller percentage of NGM/EE users than NETA/EE users during each of six cycles (p < or = 0.002). The incidence of BTB/BTS ranged from 3.7% to 13.5% for NGM/EE users and from 23.5% to 49.7% for NETA/EE users. Significantly fewer NGM/EE users than NETA/EE users experienced absence of menses at cycles 2 through 6 (p < or = 0.003). The percentages of women having no menses at each cycle ranged from 0.9% to 4.7% for NGM/EE users and from 10.3% to 21.3% for NETA/EE users. NGM/EE users reported a significantly (p < 0.001) higher level of satisfaction with their OC at the end of six cycles than did NETA/EE users, but there was no significant difference in compliance, discontinuation rates, or adverse events between the two groups. NGM/EE produced a significantly (p < or = 0.001) greater beneficial effect on HDL-C, HDL2, and apo A-I than did NETA/EE. No statistically significant treatment differences were found for total cholesterol, LDL-C, triglycerides, or apo-B. Both OC increased sex hormone binding globulin and decreased free testosterone, but NGM/EE had a significantly greater effect (p < 0.009).

Androgens↗
PubMed1999

Salivary estradiol and progesterone levels in conception and nonconception cycles in women: evaluation of a new assay for salivary estradiol.

OBJECTIVE: To determine the usefulness of salivary E2 and progesterone for noninvasive assessment of ovarian function. DESIGN: Prospective study of salivary hormone levels in women planning a pregnancy. SETTING: Department of Obstetrics and Gynecology at Northwestern University Medical School in Chicago, Illinois. PATIENT(S): Fourteen women aged 23-39 years with regular menstrual cycles who were planning a pregnancy. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Salivary estradiol and progesterone concentrations. RESULT(S): The sensitivity of the E2 assay is 2.0 pmol/L; the interassay coefficient of variation was 5.2% (mean value 17 pmol/L). Recovery of E2 added to saliva was 106%. The correlation with simultaneous serum samples was 0.71. Menstrual cycle patterns contained a preovulatory depression and a midcycle surge. By comparison with nonconception cycles, the luteal phases of conception cycles had significantly elevated salivary E2 within the first 5 days after ovulation. Salivary progesterone was significantly elevated but not until 10 days after ovulation. CONCLUSION(S): Salivary measurements of E2 and progesterone can be used as noninvasive methods for assessment of ovarian function. Salivary specimens can be collected at home and brought to the laboratory for analysis, obviating the need for frequent phlebotomy. The sensitivity and precision of the salivary E2 assay make it comparable with assays of serum E2 for assessing changes in hormone levels.

Adult↗
PubMed1999

A randomized controlled trial of four doses of transdermal estradiol for preventing postmenopausal bone loss. Transdermal Estradiol Investigator Group.

OBJECTIVE: To determine the effects of four doses of a 7-day transdermal 17beta-estradiol (E2) delivery system, including 0.025 mg/day, on bone loss in postmenopausal women. METHODS: This was a multicenter, double-masked, randomized, placebo-controlled study of the effects of transdermal E2 at doses of 0.025, 0.05, 0.06, and 0.1 mg/day for the prevention of postmenopausal osteoporosis. Efficacy was evaluated from bone mineral density of lumbar vertebrae L2-L4, radius, proximal femur, and total hip measured with dual-energy x-ray absorptiometry. Serum osteocalcin and urinary pyridinoline and deoxypyridinoline concentrations were measured. RESULTS: At 24 months, E2 doses of 0.025, 0.05, 0.06, and 0.1 mg/day resulted in mean increases in bone mineral density of the lumbar spine of 2.37%, 4.09%, 3.28%, and 4.70%, respectively, and increased bone mineral density of the total hip by 0.26%, 2.85%, 3.05%, and 2.03%, respectively. All increases were statistically significantly greater than placebo, which decreased bone mineral density by 2.49% at the spine and 2.04% at the hip. Consistent and significant improvements in biochemical markers of bone turnover also were noted at various intervals in all treatment groups. The most frequent adverse events were local reactions from the transdermal drug-delivery system, effects of estrogen, and menopausal symptoms. CONCLUSION: Transdermal E2 at doses of 0.025, 0.05, 0.06, and 0.1 mg/day effectively prevented bone loss in postmenopausal women.

Administration, Cutaneous↗
PubMed2000

Effects on serum lipid profiles of continuous 17beta-estradiol, intermittent norgestimate regimens versus continuous combined 17beta-estradiol/norethisterone acetate hormone replacement therapy.

OBJECTIVE: To compare the effects of a daily oral 1-mg dose of continuous 17beta-estradiol (E2) plus intermittent (3 days off, 3 days on) norgestimate (NGM) 90 microg (n = 221), an oral 2-mg dose of continuous E2 plus intermittent NGM 180 microg (n = 219), and an oral 2-mg dose of continuous E2 plus continuous norethisterone acetate (NETA) 1 mg (n = 217) on blood lipids and lipoproteins in postmenopausal women. BACKGROUND: The present study was undertaken because some progestins have adverse effects on lipid profiles, thereby negating the favorable effects of estrogens. METHODS: This was a multicenter, randomized, parallel-group trial that focused primarily on the 2 marketed regimens--E2 1 mg/NGM 90 microg and E2/NETA. Both subjects and investigators were blinded to the intermittent regimens; the continuous combined regimen was administered open-label. After a minimum 12-hour overnight fast, blood samples were collected at baseline and during months 7 and 12 to determine lipid and lipoprotein concentrations using validated methods. RESULTS: E2 1 mg/NGM 90 microg was associated with significant (ie, the 95% CI did not include 0) increases in high-density lipoprotein cholesterol (HDL-C) (6.8% [95% CI = 4.7%, 9.0%] and 4.8% [2.3%, 7.2%] at months 7 and 12, respectively) and high-density lipoprotein 2 cholesterol (HDL2-C) (10.8% [6.2%, 15.3%] and 24.1% [18.9%, 29.4%]) concentrations, and decreases in total cholesterol (-7.7% [-9.0%, -6.3%] and -9.2% [-10.5%, -7.9%]), low-density lipoprotein cholesterol (-14.3% [-16.3%, -12.4%] and -14.9% [-16.7%, -13.2%]), and lipoprotein(a) (-30.6% [-41.4%, -20.0%] at month 12) concentrations. A significant difference (P < 0.001 by analysis of variance) between the E2 1-mg/NGM 90-microg and NETA regimens was seen for HDL-C and HDL2-C concentrations, which were elevated in subjects receiving E2 1 mg/NGM 90 microg but reduced (-9.1% [-11.1%, -7.1%] and -12.3% [-14.3%, -10.3%] for HDL-C at months 7 and 12, respectively; -14.2% [-18.0%, -10.4%] and -2.5% [-7.8%, +2.8%] for HDL2-C at months 7 and 12, respectively) in those receiving E2/NETA. CONCLUSIONS: In the present study, continuous E2 1 mg/NGM 90 microg was associated with beneficial effects on lipids and lipoproteins in healthy postmenopausal women, effects that were greater at least for HDL-C and HDL2-C than those observed with continuous combined E2/NETA. The applicability of the study results to women with preexisting cardiovascular disease or dyslipidemia, or those who are overweight, remains to be investigated.

Administration, Oral↗
PubMed2001

Examination of estradiol effects on the rapid estradiol mediated increase in hippocampal synaptic transmission in estrogen receptor alpha knockout mice.

Hippocampal slices from rats exhibit a rapid increase in basal synaptic transmission following 17 beta-estradiol (E(2)) application. In the current study we examined the role of the classic genomic receptor, estrogen receptor alpha (ER alpha), in mediating E(2) effects on synaptic transmission. E(2) (100 pM) increased the extracellular synaptic response in hippocampal slices from gonadectomized male and female mice lacking a functional ER alpha knockout (ER alpha KO) and wild-type (WT) littermates. No sexually dimorphic differences were observed, however, the increase in the field potential was more pronounced in WT mice. ER antagonists did not block E(2) mediated growth of the synaptic response in ER alpha KO mice. The results suggest that the rapid effect of E(2) on synaptic transmission is not mediated by ER alpha, however, ER alpha appears to modulate non-genomic influences on synaptic transmission.

Animals↗
PubMed2002

Intermittent progestin administration as part of hormone replacement therapy: long-term comparison between estradiol 1 mg combined with intermittent norgestimate and estradiol 2 mg combined with constant norethisterone acetate.

BACKGROUND: To decrease exposure to progestin during hormone replacement therapy (HRT), a novel oral regimen consisting of constant 17beta-estradiol (E2) daily plus intermittent norgestimate (NGM) has been developed. METHODS: A multicenter study compared the safety and efficacy of E2 1 mg daily plus intermittent NGM 90 micro g (3 days off, 3 days on) (n = 150) vs. a continuous oral dose of E2 2 mg plus norethisterone acetate (NETA) 1 mg (n = 172) daily, for a period of 2 years. Endometrial biopsies were performed at 1 and 2 years. Subjects recorded the occurrence of vasomotor symptoms, uterine bleeding, and adverse events on diary cards. RESULTS: At 2 years' follow-up, no subject had developed endometrial hyperplasia or cancer. Endometrial atrophy was seen in 75% of subjects using the intermittent NGM regimen and in 78% of women using the constant NETA regimen. Both groups maintained a 96% reduction in vasomotor symptoms up to 2 years. The rates of bleeding and/or spotting showed no difference between the groups, and at 2 years' follow-up, 73% of women in the intermittent NGM group and 83% of subjects in the constant NETA group were amenorrheic. There was a lower incidence of progestin-associated side-effects, such as abdominal discomfort, edema, painful bleeding episodes, and breast symptoms, with the intermittent progestin regimen vs. the constant progestin regimen. Intermittent NGM use was associated with an elevation in HDL- and HDL2-cholesterol, whereas constant NETA reduced these lipoproteins. CONCLUSIONS: The intermittent administration of a progestin, such as NGM, provides a new, well-tolerated regimen to achieve endometrial safety, an adequate rate of amenorrhea, and effective reduction of vasomotor symptoms in postmenopausal women.

Adult↗
PubMed2005

Bleeding profile and endometrial safety of continuous combined regimens 1 mg 17beta-estradiol/trimegestone versus 1 or 2 mg 17beta-estradiol/norethisterone acetate in postmenopausal women.

OBJECTIVE: To compare the bleeding profile and endometrial safety of continuous combined 1 mg 17beta-estradiol (17beta-E2) and 0.125 mg trimegestone (TMG) with those of two continuous combined 17beta-E2 and norethisterone acetate (NETA) regimens. STUDY DESIGN: This was a double-blind, randomized, multicenter study conducted in 12 European countries and Israel over a 2-year period. Healthy postmenopausal women with an intact uterus were given either 1 mg 17beta-E2/0.125 mg TMG, 2 mg 17beta-E2/1 mg NETA or 1 mg 17beta-E2/0.5 mg NETA for up to 26 cycles, each of 28 days. RESULTS: The percentage of amenorrheic women was greater in most cycles up to cycle 13 in the 1 mg 17beta-E2/0.125 mg TMG group than in the comparator groups. The mean number of bleeding days was similar in the 1 mg 17beta-E2/0.125 mg TMG and the 1 mg 17beta-E2/0.5 mg NETA groups, but greater in the 2 mg 17beta-E2/1 mg NETA group. No endometrial hyperplasia was observed for any group. CONCLUSION: Continuous combined 1 mg 17beta-E2/0.125 mg TMG exhibits a more favorable bleeding profile than 1 mg 17beta-E2/0.5 mg NETA up to 1 year, while providing an adequate protective effect on the endometrium.

Double-Blind Method↗
PubMed1979

Estrogen receptor assay of mammary carcinomas. Effects of testosterone-estradiol-binding globulin (TeBG) and serum estradiol-17 beta.

To test the hypothesis that the serum sex steroid-binding protein, TeBG, might contaminate mammary carcinoma cytosols sufficiently to interfere with assay for estrogen receptor (ER), studies of tritiated estradiol-17 beta (3H-E2) binding were done following saturation with steroid hormones or after heat treatment of cytosol. Cytosols with appreciable 3H-E2 binding consistently showed a high degree of saturability with nonradioactive E2 and diethylstilbestrol (DES), and much less saturability with 5 alpha-dihydrotestosterone (DHT). Furthermore, they manifested heat-lability of 3H-E2 binding. These characteristics indicated that little, if any, TeBG was being detected in most cytosols, and that the amounts of TeBG present were not sufficient to interfere with the ER assay. Study of the relationship between serum E2 concentration at time of removal of the carcinoma and results of ER assay confirmed the need to interpret negative ER assays obtained for premenopausal women cautiously when serum E2 levels exceed approximately 300 pg/ml.

Adult↗
PubMed2002

Percentile curves of serum estradiol levels during controlled ovarian stimulation in 905 cycles stimulated with recombinant FSH show that high estradiol is not detrimental to IVF outcome.

BACKGROUND: High, normal and poor responders are usually defined by reference to subjectively selected estradiol E2 levels at days 4-6 and the day of hCG administration (d-hCG). The purpose of this study was to use E2 percentile curves from day 5 until d-hCG to determine high, normal and poor responders, and to predict IVF outcome. METHODS: In this retrospective study, 762 patients underwent 905 cycles with a GnRH agonist/recombinant FSH short protocol. They were divided into three groups according to their age. Percentile E2 curves according to E2 levels were plotted. High responders were those patients with E2 levels above the 90th percentile, normal responders had E2 between the 10th and 90th percentiles, and poor responders had E2 below the 10th percentile. RESULTS: IVF outcome, expressed as number of oocytes, total embryos obtained and number of high grade embryos, was significantly better for patients with E2 above the 90th percentile at d-hCG for the three age groups and at day 5 for group A (<35 years). Pregnancy rates were higher for high responders, but the difference did not reach statistical significance. CONCLUSIONS: Percentile curves can be useful in controlled ovarian stimulation cycles to define high, normal and poor responders, and also to predict IVF outcome.

Adult↗
PubMed2002

Development of a physiologically based pharmacokinetic model for estradiol in rats and humans: a biologically motivated quantitative framework for evaluating responses to estradiol and other endocrine-active compounds.

A physiologically based pharmacokinetic (PBPK) model for estradiol (E2) in rats and humans (male and female) was developed to provide a quantitative tool for evaluating the importance of physiological parameters on E2 blood and tissue concentration time-course and for predicting blood and tissue concentrations in rats and humans. A hepatic extraction model was developed to evaluate the significance of plasma protein binding on the hepatic extraction of E2 and the approach was integrated into the E2 model. Sufficient data was available to parameterize and validate oral and iv routes. The E2 model simulations of E2 blood and tissue concentrations compared well to experimental values. Estrogen receptor content strongly impacts distribution and elimination kinetics of E2 as well as tissue concentrations. The prolonged terminal elimination phase seen after iv bolus administration reflects the slow release of receptor bound E2 from tissues. E2 uptake behavior in the ovariectomized, but not intact rat uterus, was best described as diffusion-limited. Simulations with the hepatic extraction model predicted extensive binding of E2 to albumin (rat) and SHBG (sex-hormone binding globulin humans), although hepatic extraction does not appear to be restricted to the unbound fraction, implying that the total plasma E2 concentration is important when considering hepatic uptake. Important determinants of E2 disposition are tissue ER content and binding affinity, nonreceptor binding proteins, vascular permeability, partition coefficients, hepatic blood flow, and extrahepatic metabolism. As an integral part of a research program, the quantitative framework developed for E2 can be extended to other endocrine-active compounds (EACs) and used to evaluate the biological activity of EACs.

Algorithms↗
PubMed1988

Aging and chronic estradiol exposure impair estradiol-induced cornification but not proliferation of vaginal epithelium in C57BL/6J mice.

Long-term exposure of adult female rodents to estrogen has many deleterious effects on reproductive neuro-endocrine structure and function, but its effects on peripheral target tissues are not well known. This study was designed to determine whether chronic exposure of young mice to estradiol (E2) alters the response of the vagina to E2, and if so, whether aging potentiates this alteration. Eight-week-old mice were ovariectomized (ovx) and given subcutaneous Silastic or polyethylene (PE) implants containing E2. Silastic implants produced supra-physiologic E2 levels, while E2 levels in PE-implanted mice were within the physiologic range. Initially all E2-exposed mice showed vaginal cornification (CORN). However, CORN soon began to decline and was virtually absent 3-5 mo after implantation, despite evidence of continued, albeit reduced, release of E2 from the implants. Mice were reimplanted with new E2 implants to determine whether the loss of CORN resulted from an altered response to E2 or from a decreased release of E2 from the implants. Vaginas of mice previously exposed to either Silastic (high E2) or PE (low E2) implants failed to cornify in response to new E2 implants, whereas vaginas of mice that had been initially exposed to implants without E2 cornified in response to identical E2 implants. When old (23 mo) acutely ovx mice were given E2-containing Silastic implants, the peak level and duration of CORN were only one-third and one-fifth, respectively, of that seen in young mice. Non-cornifying epithelia from both young and old chronically E2-exposed mice were as hyperplastic and active mitotically as cornifying epithelia, indicating that the loss of CORN was not a result of decreased epithelial proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Estradiol influences on pattern of gonadotropin secretion in bovine males during the period of changed responses to estradiol feedback in age-matched females.

When ovaries are removed prior to puberty, administration of exogenous 17 beta-estradiol (E2) decreases concentrations of luteinizing hormone (LH) below that of ovariectomized heifers receiving no E2. Subsequent to the time age-matched intact heifers reach puberty, exogenous E2 increases secretion of LH in ovariectomized heifers above that of ovariectomized heifers receiving no E2. The hypothesis that E2 would inhibit gonadotropin secretion in bovine males during the time E2 no longer inhibited gonadotropin secretion in age-matched bovine females was tested. Males (n = 12) and females (n = 12) were gonadectomized at 241 +/- 3 days of age, and half of each sex (6 males and 6 females) were administered a 27-cm E2 implant. An additional group of males (n = 6) and females (n = 6) remained intact and served as controls. Blood samples were collected (to quantify LH and follicle-stimulating hormone [FSH]) from all animals at 15-min intervals for 24 h at 1, 7, 13, 17, 21, 25, 29, 33, 37, and 43 wk after gonadectomy. Additional blood samples were collected twice weekly from control females to monitor progesterone and onset of corpus luteum function (451 days of age). E2 inhibited frequency of pulses of LH (p less than 0.01) and decreased mean concentration of LH and FSH (p less than 0.01) at Week 1 in gonadectomized males treated with E2 compared to gonadectomized males not administered E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Estradiol modulation of growth hormone secretion in the ewe: no growth hormone-releasing hormone neurons and few somatotropes express estradiol receptor alpha.

Evidence suggests that estrogen modulates growth hormone (GH) release and that GH plays an important role in follicular and ovulatory processes. How estradiol affects GH secretion is unclear. Having verified that there is a coincident surge of GH at the time of the preovulatory LH surge, immunocytochemical studies incorporating high-temperature antigen retrieval were used to determine whether GH-releasing hormone (GHRH) neurons, somatotropes, or both, expressed estrogen receptor alpha (ER), in the ewe. Although GHRH neurons were surrounded by many ER cells, they did not express immunocytochemically detectable ERs. In contrast to gonadotropes, in which the majority expressed ERs, few somatotropes were estrogen receptive. These data suggest that estrogen does not act directly on GHRH neurons to influence GH secretion, and any direct effect on pituitary GH release, through the ERalpha, may be small.

Animals↗
PubMed2005

Oral hormone therapy with 17beta-estradiol and 17beta-estradiol in combination with norethindrone acetate in the prevention of bone loss in early postmenopausal women: dose-dependent effects.

OBJECTIVE: A 2-year multicenter, double-blind, randomized, placebo-controlled study examined the efficacy and safety of different doses of 17beta-estradiol (E(2)) alone and continuous-combined oral formulations of E(2) and norethindrone acetate (NETA) versus placebo in the prevention of bone loss in newly menopausal women. DESIGN: Patients were randomized to one of seven groups: placebo, E(2) 0.25 mg, E2 0.5 mg, E(2) 1 mg, E(2) 1 mg/NETA 0.25 mg, E(2) 1 mg/NETA 0.5 mg, or E(2) 2 mg/NETA 1 mg. Treatment was a once-daily tablet taken for 26 months. The primary efficacy endpoint was the change in bone mineral density (BMD) at the lumbar spine, measured by dual-energy x-ray absorptiometry, at screening and at 13, 19, and 26 months. BMD changes at the femoral neck and trochanter were also assessed. Biochemical markers of bone metabolism were measured at baseline, and at 3, 6, 13, 19, and 26 months. Histological diagnoses of endometrial samples were tabulated for each treatment group. RESULTS: A total of 327 women were randomized and 189 women completed the 2-year trial. BMD at the lumbar spine decreased 2.3% in the placebo group. The lowest dose of unopposed E(2) prevented bone loss at the spine and hip. Significant increases in spine BMD compared with placebo occurred in all groups of treatment with E(2) and were more pronounced in the combination groups. Compared with placebo, women receiving active treatment experienced greater reductions in bone resorption markers. The effects were evident by 6 months and generally remained stable thereafter. Adverse events, primarily associated with the endometrium, were the most common reasons for discontinuation. CONCLUSIONS: There is a dose-dependent effect of E(2) on BMD. The addition of NETA seems to enhance the response in BMD observed with E(2). Low doses of E(2) (1 mg and lower) can be considered for the prevention of osteoporosis, while titrating the hormone dose to individual patient's needs.

Administration, Oral↗
PubMed1985

Measurement and characterization of swine uterine estradiol receptors: the effects of puberty induction on estradiol receptors and corpus luteum function.

Two types of cytoplasmic 17 beta-estradiol (E2) binding activity were identified and characterized in the uteri of pregnant, cycling and prepubertal, cycle-induced (400 IU pregnant mare's serum gonadotrophin (PMS) + 200 IU human chorionic gonadotrophin (hCG)) gilts. Overall, type I affinity and capacity were Kd 1.94 +/- 0.51 nM and 5.410 +/- 1.09 pmol/mg protein, respectively; type II apparent dissociation constant and capacity were Kd 21.34 +/- 6.83 nM and 62.58 +/- 15.96 pmol/mg protein, respectively. Cytoplasmic luteal E2 receptors were undetectable in all groups. Uterine E2 receptor activity was eluted from diethylaminoethyl columns by a 0.05-0.15 M KCl gradient. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated a molecular weight of 70 400-79 000. Excluding gilts with cystic ovarian follicles (16.67%), prepubertal gilts treated with PMS + hCG versus cycling sows had lower serum progesterone on days 6 and 9-13 of the estrous cycle and lower 13,14-dihydro-15-keto prostaglandin F2 alpha levels on days 0-9 and 13-17 of the cycle. Implants, containing 200 mg estrone inserted subcutaneously on days 12-19 after PMS + hCG treatment in gilts, had no discernible effects on these parameters. These results indicate that the diminished reproductive capacity of the gilt, in which cycle activity is induced by PMS + hCG, is likely due to decreased luteal progesterone secretion. Preliminary data also suggest that the lack of E2 receptors may contribute to the low reproductive performance in gilts with cystic ovarian follicles.

Animals↗
PubMed1983

Anovulation in female rats induced by neonatal administration of the catechol estrogens, 2-hydroxy-estradiol and 4-hydroxy-estradiol.

The effects of estradiol (E2) and its 2- and 4-hydroxylated metabolites on gonadotrophin regulation in the female rat brain were examined. Neonatal female rats were injected from day 1 through 5 with E2, 2-OHE2 and 4-OHE2, at doses of 0.1, 1 and 10 micrograms/day. At 2, 6 and 24 h after the last estrogen injection, some animals from each treatment group were killed and the concentration of estrogen receptors (ERn) in their brain cell nuclei determined. The remaining animals were allowed to mature. Their vaginal smear patterns were examined from 7 to 9 and from 15 to 17 weeks of age. They were then ovariectomized and tested for their capacity to exhibit a luteinizing hormone (LH) surge in response to estrogen and progesterone injections. In a parallel series of experiments, the affinities of the three test estrogens for alpha-fetoprotein (AFP) were determined from in vitro competition studies with fetal rat serum. All three estrogens increased brain cell nuclear ERn concentrations, measured at 2 h after the final injection. E2 was more potent in this respect than either 4-OHE2 or 2-OHE2. E2 and 4-OHE2 competed for binding to AFP to an approximately equal extent. 2-OHE2, however, was a much weaker competitor for AFP than either of the other two compounds. The neonatal E2 and 4-OHE2 treatments reduced the number of animals showing regular cyclic vaginal smears, at all three doses tested. In contrast, 2-OHE2 significantly affected vaginal cyclicity only at a dose of 10 micrograms/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗