Anti-implantation activity of antiestrogens and mifepristone

To develop a better postcoital contraceptive, the following antiestrogens were tested for their anti-implantation activity in the rat: anordrin, anordiol, tamoxifen, ICI 182,780, and RU 39411. The compounds were administered orally or subcutaneously (s.c.) to female rats on days 1, 2, and 3 of pregnancy. All the antiestrogens tested were 100% effective in preventing blastocyst implantation. The lowest effective doses when administered orally were 10, 1.25, 0.062, 6.0 (partially effective), and 0.01 mg/kg/day, respectively. The estimated median effective doses (ED50) were 5.60, 0.40, 0.035, 5.40, and 0.0074 mg/kg/day, respectively. When administered s.c., the minimum effective doses in preventing blastocyst implantation in all animals were 2.0, 0.1, 0.1, 0.1, and 0.01 mg/kg/day, respectively. Anordrin, anordiol, and ICI 182,780 were more potent when administered s.c.; whereas tamoxifen and RU 39411 were effective at similar doses when administered parenterally or orally. RU 39411 was the most potent among the antiestrogens tested and should be evaluated as a potential postcoital contraceptive. The administration of mifepristone, an antiprogestin, at a dose of 8 mg/kg/day blocked blastocyst implantation in all treated animals; whereas at a dose of 4 mg/kg/day or lower, the drug was ineffective. These findings confirm that estradiol and progesterone are essential for blastocyst implantation in the rat. The capacity of mifepristone to potentiate the anti-implantation activity of the antiestrogens was also determined. The combination of a non-effective dose of each of the antiestrogens (anordrin, anordiol, and tamoxifen), and RU 39411, with mifepristone at a non-effective dose, prevented pregnancy, demonstration that an antiprogestin and antiestrogen act synergistically in blocking blastocyst implantation in the rat. The antiestrogen compounds whose anti-implantation activities were potentiated by mifepristone were found to possess significant estrogenic activity, when assayed by measuring the increase in the uterine weights of ovariectomized rats. The only exception was ICI 182,780, which showed no estrogenic activity in the uterine weight bioassay and did not act synergistically with mifepristone in blocking blastocyst implantation. Estradiol was effective in preventing pregnancy at a dose of 1 microgram/kg/day. The combination of non-effective doses of estradiol and mifepristone did not prevent pregnancy. The findings that mifepristone potentiates the anti-implantation activity suggests that the synergistic effect may be a unique property of this class of antiestrogens.

Intracervical 17 beta-oestradiol before induction of second-trimester abortion with a prostaglandin E1 analogue

28 consecutive patients (17.5 weeks pregnant, range 15-21 weeks) referred for therapeutic termination of pregnancy were randomized for pretreatment overnight with either intracervical gel containing 50 mg 17 beta-oestradiol or placebo gel. The induction-abortion time with pessaries containing 16,16-dimethyl-trans-delta 2-prostaglandin E1 methyl ester was significantly reduced in the oestrogen group (median value of 11.5 versus 15 hours). The beneficial effect of oestradiol priming was primarily caused by a reduction of the number of women with high cervical resistance and prolonged induction-abortion time (90 percentiles of 15.5 and 34 hours). Thus, oestrogen pretreatment might reduce the cervical trauma due to the prostaglandins as well as the incidence of cervical incompetence in later pregnancies.

Transdermal delivery of steroids

The advantages of delivering drugs through the skin for systemic therapy have been widely recognized and represent a growing sector in drug development. Transdermal delivery of steroids is also a rapidly expanding field and in various clinical situations where hormonal replacement therapy is needed this route of administration is a real breakthrough, considering the relative toxicity of some steroids when given orally. Various transdermal systems have been designed, all of them aimed at achieving a constant release rate of the molecules contained in their reservoir through the intact skin. The skin itself, and especially the outermost layer, the stratum corneum, can play the roles of a reservoir and a rate-controlling membrane. So far, estradiol, progesterone and testosterone have been demonstrated to be good candidates for transdermal delivery. The effectiveness and the acceptability of transdermal delivery of estradiol in postmenopausal women have been demonstrated. The efficacy of topical administration of progesterone in patients with benign breast disease has also been proved. More recently, the high rate of acceptability and efficacy of transdermal testosterone in male hypogonadism has been demonstrated. The transdermal delivery of steroids is therefore expected to make a significant impact on the quality of patient care both in men and in women.

New natural oestradiol/cyproterone acetate oral contraceptive for pre-menopausal women

Fifty (50) healthy ovulating women aged between 35 and 47 yr (mean age 39) were randomly allocated to one of two groups treated with biphasic formulations of either oestradiol valerate/cyproterone acetate (Group A) or oestradiol valerate/norethisterone (Group B). A double-blind design was used during the first 6 mth of treatment. In Group A, 21 out of 26 women (81%), and in Group B, 16 out of 24 (67%) completed the first year of treatment. No pregnancies occurred. The mid-cycle serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) peaks were suppressed, but there were no differences between the pretreatment serum oestradiol values and those observed during the treatment cycles. The serum progesterone values indicated that only one ovulatory cycle occurred during the first year in Group A, while there were 11 in Group B. Ultrasonic studies revealed follicular growth during treatment in both groups, most follicles becoming atretic or persistent without ovulation. No significant changes were observed in 11 coagulation factors studied in 16 women in Group A. Serum total cholesterol decreased by about 10% in both groups. In Group A bleeding became scantier and dysmenorrhoea disappeared. The incidence of spotting varied between 30% and 40%, but it is important to note that the total number of bleeding days per cycle fell. The oestradiol valerate/cyproterone acetate combination was thus found to inhibit ovulation, provide tolerable cycle control and to be free from adverse metabolic side effects.

Contraception in hypertensive women using a vaginal ring delivering estradiol and levonorgestrel

Contraception with a vaginal ring (CVR) that delivers estradiol and levonorgestrel was used during a mean of 15.6 menstrual cycles in 12 hypertensive women. Blood pressure (BP) was measured 5 times on each visit during 2 pretreatment control cycles; during the 1st, 2nd, 4th, 6th, and from the 9th to 12th cycles of CVR use; and again after a 1-month recovery period. No significant change in BP occurred during CVR use in any of the subjects. Plasma renin substrate and antithrombin III activity did not vary significantly, which suggests the utility of administering natural estradiol via the vagina, thus avoiding the first pass effect that occurs with oral contraceptives. Significant decreases in plasma sex hormone-binding globulin, cholesterol, high density lipoprotein cholesterol, phospholipids, and triglycerides occurred, indicating an androgenic effect of levonorgestrel. We conclude that the CVR is a method of contraception that does not elevate BP in hypertensive women.

[Contraception in the hypertensive woman using a vaginal ring delivering estradiol and norgestrel]

A long term prospective study of contraceptive vaginal rings (CVR) that deliver estradiol and D-Norgestrel was conducted in 12 hypertensive women. Blood pressure was measured five times by an oscillometric automatic device during two control cycles, at the 1st, 2nd, 4th, 6th and 9th to 12th cycle of CVR use, and again after a one month recovery period. No significant change in blood pressure was noted during CVR usage and this method of contraception appeared safe in hypertensive women. Plasma renin substrate and plasma antithrombin III were non affected by the treatment. These observations are in marked contrast with the dramatic increase and decrease in these proteins that are respectively observed during oral estroprogestative contraception; and confirm the utility of a way of hormone administration that bypass the liver. The significant decrease in sex binding protein, HDL cholesterol, phospholipids and triglycerides that were observed under CVR treatment could be interpreted as reflecting the androgenic potency of D-Norgestrel.

Effects of two estradiol/norgestrel combinations on the ovulatory pattern and on sex hormone binding globulin capacity in women around forty years of age

Thirteen women aged 36-46 years (mean 43) who were seeking contraceptive advice, were monitored for 3 months with basal body temperature (BBT) and were then treated for 3 months with CyclabilR (11 tablets of 2 mg estradiol valerate (E2) followed by 10 tablets of 2 mg E2 + 0.5 mg norgestrel). This treatment was immediately followed by another 3 months with CyclabilR + 2 mg E2. BBT revealed a spontaneous ovulatory rate of 89%. Cyclabil reduced the ovulatory rate, as measured with repeated serum progesterone analyses, to 37%, and Cyclabil + 2 mg E2 resulted in a marked reduction in the number of ovulations (3%). Both types of hormonal combination resulted in relatively small changes in Sex Hormone Binding Globulin Capacity. It is concluded that the addition of 2 mg E2 to CyclabilR causes a decrease in ovulation rate to such an extent that women using this combination run a relatively small risk of conceiving. One advantage over contraceptive steroids may be that the present combination contains a natural estrogen at a relatively low concentration.

Apparent oral contraceptive failure associated with antibiotic administration

The concomitant use of antibiotics and oral contraceptives should be included in the assessment of contraceptive failure. A case of unwanted adolescent pregnancy during the use of a semisynthetic penicillin and an oral contraceptive is presented and discussed. Advising a different contraceptive method or an additional contraceptive modality may be indicated in adolescents taking long-term antibiotic medication.

Somatic tissue responses of male rhesus monkeys treated with a contraceptive steroid formulation

Rhesus monkeys (Macaca mulatta) were treated with testosterone (100 micrograms/kg/day) plus estradiol (0.5 micrograms/kg/day) via subcutaneous polydimethylsiloxane (PDS; Silastic) implants for thirteen months. This steroid regimen inhibited dramatically spermatogenesis. Gross and histopathological examination of the musculoskeletal, circulatory, endocrine (excluding the testis), central nervous, gastrointestinal and respiratory systems failed to uncover any untoward effects of the long-term exposure due to the contraceptive formulation. Similarly, no remarkable effects were observed in the ionic, chemical and formed elements of blood or secondary sex structures. Failure to detect secondary complications attributed to the steroid treatment offers further justification for evaluating a contraceptive strategy based on administering naturally occurring steroids at sustained rates approximating those at which they are produced endogenously in the human male.

Testis function in rhesus monkeys treated with a contraceptive steroid formulation

Rhesus monkeys (Macaca mulatta) were treated with testosterone (100 micrograms/kg/day) plus estradiol (0.5 micrograms/kg/day) via subcutaneous polydimethylsiloxane (PDS;Silastic) implants for thirteen months. This steroid regimen inhibited LH but not FSH secretion by the anterior pituitary, inhibited testicular testosterone and estradiol production and drastically reduced the numbers of vigorously motile spermatozoa in the ejacula. Importantly, these effects on testis function were achieved at dosages of testosterone and estradiol which approximate the amount of these two steroids produced daily in normal rhesus males.

Effects of oestradiol and levonorgestrel on lipoprotein lipids and postheparin plasma lipase activities in normolipoproteinaemic women

The effects of oestradiol and levonorgestrel on plasma lipoprotein cholesterol (Chol) and triglyceride (Tg) levels and on postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activity were studied in 52 normolipoproteinaemic women. The androgen-derived progestin levonorgestrel increased postheparin plasma hepatic lipase (PH-HL) activity and decreased plasma high-density lipoprotein (HDL) lipid concentrations in a manner opposite to that of oestradiol. The relationships between PH-HL activity and HDL lipids suggest an important role for this enzyme as a mediator of sex hormone action on HDL.

Development of a vaginal ring for achieving physiologic levels of 17 beta-estradiol in hypoestrogenic women

The ability of polysiloxane vaginal rings containing 17 beta-Estradiol (E2) to deliver E2 into the systemic circulation at a steady rate over long periods of time was evaluated in castrate and postmenopausal volunteers. Standard laminar designs, used to release contraceptive gestagens, deliver low levels of E2 (about 50 pg/ml) and only for 1 month. With a modified design, E2 levels of 109 to 159 pg/ml were maintained for at least 3 months, and circulating gonadotropins were suppressed to values approaching the premenopausal range. This homogeneous design provides for physiologic replacement of E2 as well as a practical research tool for studying chronic effects of E2 in human subjects.

Effects of different progestogens on lipoproteins during postmenopausal replacement therapy

To study the effects of different types of progestogens on lipoprotein metabolism, we treated three groups of postmenopausal women (six subjects each) for three weeks with estradiol valerate, 2 mg per day, and continued the treatment with different sequential estradiol-progestogen regimens as follows: Group A received norethindrone acetate, 10 mg per day, from Day 15 to Day 24 of the cycle; Group B, medroxyprogesterone acetate, 10 mg per day; and Group C, norgestrel, 0.5 mg per day. These regimens were followed by two consecutive cycles. Total cholesterol decreased in all groups by 10 to 18 per cent from the base-line values (P < 0.05). High-density-lipoprotein (HDL) cholesterol decreased by 20 per cent from the base-line level during treatment with both the estradiol-norethindrone acetate (P < 0.05) and estradiol-norgestrel (P < 0.01) regimens, whereas estradiol with medroxyprogesterone acetate was not associated with a significant change in HDL cholesterol. Our results suggest that the androgenic progestogens of the 19-nortestosterone series reverse the beneficial effect of postmenopausal estrogen treatment on HDL cholesterol, whereas the hydroxyprogesterone derivative medroxyprogesterone acetate has no such effect.

17 beta-estradiol levels in blood and cerebrospinal fluid after ocular and nasal administration in women and female rhesus monkeys (Macaca mulatta)

17 beta-estradiol was applied ocularly to menstruating and postmenopausal women. The absorption by blood was measured. A rapid increase of both estradiol and estrone was seen with higher plasma levels in the menstruating group, possibly due to a better conjunctival circulation. Twenty-one rhesus monkeys were given estradiol suspension or solution ocularly or nasally. The absorption by blood and cerebrospinal fluid was measured and compared to intravenous injection of 0.5 mg estradiol. Estradiol increased in plasma after 1'. Maxima were reached at 15'. Estradiol solution gave higher plasma levels than estradiol suspension. At 5' they amounted to the levels found after i.v. injection. The estradiol levels in cerebrospinal fluid never exceeded the corresponding plasma levels and were generally low. The increase in cerebrospinal fluid was thought to be secondary to the raised plasma levels.

Endometrial effects of levonorgestrel and estradiol: A Scanning electron microscopic study of the luminal epithelium

Fertile women in the follicular phase possessed an uterine luminal surface with many ciliated cells and with non-ciliated cells, which carried numerous, fairly long microvilli. A moderate number of the non-ciliated cells had an irregular surface with small apical protrusions. Postmenopausal women had an endometrial surface containing rather flat cells. Ciliated cells were seldon encountered, and the non-ciliated cells possessed mostly only few short microvilli. When menopausal women had been wearing estradiol-containing intravaginal rings for three weeks, the uterine surface had developed many ciliated cells, and the non-ciliated cells now possessed many long microvilli. This appearance resembles that appearing during the follicular phase. Fertile women with levonorgestrel-containing subdermal implants or intravaginal rings showed a surface epithelium with few ciliated cells and with non-ciliated cells possessing short and irregular microvilli; that is, an epithelium less developed than that from a cyclic women. Adding estradiol to the levonorgestrel-containing intravaginal rings resulted in an estrogen response with an increase in number and length of the microvilli and an appearance of a few small apical protrusions.

A comparison of the pharmacokinetic properties of three estradiol esters

In order to assess the pharmacokinetics properties of estradiol cypionate, valerate and benzoate, the daily plasma levels of estradiol and estrone were analysed in groups of 10, 9 and 10 subjects, respectively, before and during 3 weeks after the intramuscular administration of a single dose of 5.0 mg in 1.0 ml arachis oil. In order to minimize the contribution of endogenous estrogens to the plasma levels, all subjects were receiving a combined oral contraceptive consisting of levonorgestrel (150 micrograms) and ethinyl estradiol (30 micrograms) for three months prior to the study and during the study period. The administration of estradiol cypionate gave significantly lower peak levels of estradiol and estrone than that of the valerate and benzoate. Peak plasma levels of estradiol and estrone were reached in approximately 4 days following the administration of estradiol cypionate and in a significantly shorter time (approximately 2 days) following the administration of both the valerate and benzoate. One hour after the injection of the esters, the average percentage increases in plasma estradiol and estrone levels were significantly higher in the valerate and benzoate groups compared to the subjects receiving estradiol cypionate. The average duration of elevated estrogen levels was shortest in the benzoate group (4-5 days) followed by the valerate (7-8 days) and cypionate (approximately 11 days). In none of the subjects studied were elevated estradiol and/or estrone levels encountered 2 weeks after the injection of the various esters. The data suggests that among the three esters studied, the valerate provides the most predictable pharmacokinetic behaviour.

Effect of natural oestrogens on tryptophan metabolism: evidence for interference of oestrogens with kynureninase

Urinary excretion of metabolites of the tryptophan-nicotinic acid ribonucleotide pathway, urinary excretion of 4-pyridoxic acid and blood concentrations of oestradiol and pyridoxal phosphate were studied in groups of post-menopausal women before or during treatment with natural oestrogens, i.e. oestradiol and oestriol, before and after loading doses of 9800 mumol L-tryptophan or 700 mumol L-kynurenine sulphate. Natural oestrogens induced abnormalities of tryptophan metabolism similar to those induced by synthetic oestrogens, and there was a dose related increase in urinary excretion of metabolites of the tryptophan-nicotinic acid ribonucleotide pathway before the kynureninase step. The increase in urinary excretion of these metabolites also after a loading dose of 700 mumol L-kynurenine indicates an inhibitory effect of oestrogens on kynureninase in vivo. Evidence is presented that this inhibition is an effect mediated through decreased availability of vitamin B6, the coenzyme of kynureninase, although the possibility of a direct effect of oestrogens on kynureninase can not be excluded.

[Administration route of natural sex steroids (estradiol, progesterone, testosterone) (author's transl)]

The natural sex steroids (E2, T, P) may be used in therapeutics. Estradiol and testosterone esters (decanoate and undecanoate) may be administered orally. A local effect always follows the percutaneous application of sex steroids, and this is usually accompanied by a systemic effect. But because of the very important metabolism of progesterone by the skin, it is necessary to administer it by other routes (intravaginal, intrarectal) in order to obtain a systemic effect.

Pharmacokinetic studies on low dose estradiol 17 beta administered orally to postmenopausal women

Peripheral plasma from four postmenopausal women was analysed for estrone, estradiol, lutenizing hormone and follicle stimulating hormone during 24 hours following an oral intake of a single dose of 1.0 mg micronized estradiol, on the first day of therapy and after one month. A similar study was carried out with another four postmenopausal patients, who received 0.2 mg estradiol three times daily. The measurements were performed by radioimmunoassay (RIA). It is concluded that the plasma concentrations of estrone and estradiol are higher and those of FSH lower after one month of therapy than on the first treatment day, while plasma LH remains unchanged. Micronized estradiol is rapidly absorbed from the gastrointestinal tract and converted to estrone, and the plasma profiles of estrone during the day are more constant with a divided daily dose than with a single higher dose. The divided daily dose results in an equally good clinical effect even though the total administration of estradiol is lower.

Interaction of estrogen and histamine during ovum implantation in the rat

The relationship between estrogen and histamine in the initiation of ovum implantation in the rat was studied. Histamine was found to augment the implantation response to suboptimal doses of estradiol in the ovariectomized pregnant rat maintained with Depo-Provera. The effect of histamine was found to involve both H1- and H2-receptors and to be inhibited by treatment with a combination of mepyramine and metiamide. Treatment with this combination of histamine antagonists during early pregnancy in the intact rat did not modify blastocyst attachment. It was concluded that the effect of histamine on the implantation response to exogenous estradiol was due to increased uterine blood flow and/or estrogen uptake but that such histamine-mediated effects were not essential for blastocyst attachment during normal pregnancy.

Serum lipids and lipoproteins during treatment with oral contraceptives containing natural and synthetic oestrogens. A controlled double-blind investigation

Increases in serum triglycerides, cholesterol and pre-β- and β-lipoproteins have been considered as significant pathogenic factors regarding the possible thrombotic side-effect of treatment with oral contraceptives of the combined type containing synthetic oestrogen. With the purpose of investigating the influence of natural oestrogen (oestradiol-17β + oestriol/norethisterone acetate) versus synthetic oestrogen (ethinyloestradiol/norethisterone acetate) on serum lipids and lipoproteins in young women compared to independent and individual controls, as controlled double-blind investigation was performed in 33 women in a total material and 18 women in a selected group. The significant changes were as follows: quantitative increases in serum triglycerides (P < 0.001) and β-lipoproteins (P < 0.01) during treatment with synthetic oestrogen, while in contrast no such change was observed in subjects on natural oestrogen, which was found to decrease serum cholesterol (P < 0.05), phospholipids (P < 0.05) and α-lipoprotein (P < 0.05). Quantitative estimation of serum lipoproteins was found to be more valuable than the relative estimation by electrophoresis. It is concluded that oral contraceptives containing natural oestrogens induce less significant and, qualitatively, more benign changes in serum lipids and lipoproteins than preparations containing synthetic oestrogen do.

The effect of prostaglandins and other vasoactive substances on uterine blood flow and myometrial activity

The effects of prostaglandins (PG's), bradykinin, and adenosine on uterine blood flow (UBF) and intrauterine pressure (IUP) were investigated in conscious oophorectomized ewes. PGE1 and adenosine increased UBF to levels comparable to those induced by estradiol-17beta, whereas PGE2 and PGA1 achieved only 20 and 36 per cent of peak estradiol-induced levels, respectively. PGE1, PGE2, and adenosine all caused transient increases in IUP while PGA1 had no effect on myometrial activity. Bradykinin increased UBF to 60 per cent of peak estradiol-induced levels, with concomitant increases in IUP tonus. PGE2 and PGF2alpha decreased peak estrogen-induced UBF by 50 and 70 per cent, respectively, while inducing related increases in IUP. When compared with oxytocin, the effects of PGE2 at high flow appeared to be mediated only my myometrial activity, whereas PGF2alpha apparently caused vasoconstriction as well. These findings support the concept that PGE1 could play a role in mediating estrogen-induced uterine vasodilatation.

Sex hormones and the immune response. II. Perturbation of antibody production by estradiol 17beta

The administration of 75 microgram/kg of estradiol 17beta at successively later stages in the immune response of female guinea pigs to penicilloyl-coupled cavian globulins showed that this steroid reduces the rate of attainment of the maximum titer, the magnitude of the titer achieved, and the rate of titer decay. Control titers maximized at the third experimental week and diminished to one third the peak value by the 6th week. When steroid treatment was begun coincidentally with inoculation (week 0), the peak titer was delayed by 3 weeks, and by 2 weeks when hormone priming was begun at week 1 or 2. The highest antibody titers achieved in the presence of estrogen were 25-30% lower than those of sesame oil controls. The greatest immunosuppressive effect was observed when estradiol was given at the peak of the immune response, the titer dropping by 50% and remaining at that level for the next 4 weeks in spite of continued antigen inoculation and steroid treatment. Titer decay after the end of the inoculation course was prevented by estradiol but not by progesterone, CHP, or these same oil vehicle.

Effects of aging on the hypothalamic-hypophyseal-gonadal axis in female rats

The failure of reproductive function in aged rats could be due to deficiencies at the level of the ovary, pituitary, hypothalamus, or higher brain centers. The classic explanation that the ovary is depleted of follicles does not receive adequate support on the basis of histologic studies of aged ovaries. Basal serum gonadotropin levels change with increasing age in female rats. Serum follicle-stimulating hormone (FSH) levels rise while serum luteinizing hormone (LH) levels fall. Likewise, the characteristic response to castration is markedly altered in aged female rats with a reduced secretion of FSH and a minimal elevation of LH. However, the pituitaires of these animals are still caapable of responding to exogenous LH-releasing hormone with a delayed LH response whose magnitude simulates that seen in younger female animals. With increasing age there is decreased pituitary and/or hypothalamic sensitivity to the feedback action of estradiol. These data are consistent with the postulation that there is an altered hypothalamic-hypophyseal function in aged rats.

Dynamic testing of hypothalamic-pituitary function in abnormalities of ovulation

A review of 26 unusual patients indicates that a combined luteinizing hormone-releasing hormone (LRH)-clomiphene test in conjunction with an estrogen provocation test not only was helpful in identifying underlying pathophysiology of anovulation but also proved useful in the clinical management of the patients. Dynamic testing per se does not establish a diagnosis but, in conjunction with history and other laboratory findings, it does make possible further subdivisions of groups of patients who otherwise appear similar, both clinically and from routine laboratory evaluations. It, therefore, tends to pinpoint a lesion and establish the area in which further tests should be made. It is concluded that the value of such investigations will be more evident as gynecologic endocrinology moves into investigation of the supratentorial control of hypothalamic function and as hypothalamic LRH becomes available as a therapeutic agent.

Luteinizing hormone-releasing hormone, ovariectomy, and silastic vaginal rings in the Rhesus monkey

The interaction of estradiol and luteinizing hormone-releasing hormone (LRH) may be a critical physiologic mechanism regulating the occurrence of ovulation in many species. These studies were conducted to assess (1) the effects of intramuscular injections of LRH in the intact female rhesus monkey and (2) the effects of estradiol in a Silastic delivery system in ovariectomized female rhesus monkeys. No changes in blood levels of luteinizing hormone (LH) were detected in response to 200 micrograms of LRH. Ovulation did not occur 48 hours after treatment. Ovariectomy decreased estradiol, increased LH, and had no effect on prolactin concentrations in sera. Insertion of a vaginal ring containing 10% estradiol increased blood estradiol levels 100-fold. Serum prolactin levels were unaffected; however, LH concentrations were altered in a multiphasic fashion. After the ring had been in place for 15 days, vaginal blood similar to menstrual flow was observed following removal.

Mechanism of oestrogen and progesterone effects on lipid and carbohydrate metabolism: alteration in the insulin: glucagon molar ratio and hepatic enzyme activity

As in women receiving oestrogens the administration of 17beta-oestradiol to ovariectomized female rats caused a rise in fasting plasma triglycerides and a fall in plasma glucose. Progesterone, on the other hand, had no significant effects. In the oestradiol treated rats, the portal vein basal insulin levels were slightly reduced. Oestradiol, however, had a marked suppressive effect on the alpha cells of the pancreas resulting in a greater reduction in basal glucagon and impaired glucagon response to alanine infusions. The relative insulin to glucagon (I/G) molar concentration ratio in portal vein blood was increased. Oestradiol also produced a dose dependent increase in the activity of the liver lipogenic enzymes, acetyl CoA carboxylase and fatty acid synthetase. On the other hand, the activity of the gluconeogenic rate limiting enzyme phosphoenol-pyruvate carboxykinase (PEPCK) was inhibited. The cross-over pattern of gluconeogenic intermediates confirmed inhibition of gluconeogenesis at this step, an effect which is similar to that induced by relative insulin 'excess'. Progesterone produced an increase in the portal vein insulin concentrations. Both the basal and the alanine-stimulated glucagon levels were also increased. The I/G molar ratio in portal vein blood of progesterone treated rats remained unaltered and the hepatic lipogenic and gluconeogenic enzyme activities were similar to control animals. These data suggest that insulin activity is increased relative to glucagon in the liver of oestradiol-treated rats due to the rise in portal vein I/G ratio. The changes in liver lipogenic and gluconeogenic enzymes and the alterations in fasting plasma triglycerides and glucose in response to oestrogens could be secondary to this effect.

The interaction of clomiphene, estradiol, and progesterone in the control of rat uterine glycogen metabolism

Uterine glycogen accumulation was studied in ovariectomized rats treated with all combinations of clomiphene citrate (0.25 mg/kg) estradiol (1.0 micron g) and progesterone (5.0 mg). The rats were given three consecutive daily dosages and killed 24 hours after the final dosage. Based on biochemical data, either estradiol or clomiphene increased uterine glycogen concentration and total glycogen, but progesterone did not. Progesterone significantly suppressed both the estradiol and clomiphene-induced glycogen increases. Based on the histochemical results, progesterone also suppressed the estradiol and clomiphene-induced glycogen responses, but the tissue affected differed. Clomiphene markedly increased luminal epithelial glycogen whereas estradiol induced primarily myometrial glycogenesis. Progesterone completely suppressed the clomiphene-induced epithelial effect and partially suppressed the estradiol-induced myometrial effect. Clomiphene also suppressed the estradiol-induced myometrial response. The results indicate that progesterone does have a significant interaction with clomiphene in the control of uterine morphology and biochemistry. The results also stress the importance of correlated histochemical and biochemical studies in the study of clomiphene-induced uterine glycognesis.

Effects of exogenous progesterone and oestradiol on prostaglandin F and 13,14-dihydro-15-oxo prostaglandin F2alpha concentrations in uteri and plasma of ovariectomized ewes

The control of prostaglandin (PG) production by steroid hormones has been investigated in non-pregnant bilaterally ovariectomized sheep, prepared with indwelling utero-ovarian venous catheters and treated with physiological amounts of oestradiol and progesterone. Oestradiol treatment alone (2 × 15 μg/day for 9 days) had no effect on the prostaglandin F (PGF) concentration in uterine caruncles or intercaruncular tissue, on the release of PGF or of 13,14-dihydro-15-oxo PGF (PGFM) from these tissues during incubation in vitro, or on the concentrations of PGF in the utero-ovarian vein or PGFM in the jugular vein. However, oestradiol did accumulate in the uterine tissues. Progesterone treatment alone (2 × 10 mg/day for 9 days) provoked a significant increase in the concentration of PGF in the caruncles, a significant increase in the release of PGF from the caruncles during incubation with arachidonic acid and increased mean concentrations of PGFM in the jugular vein. When oestradiol was superimposed on a progesterone-primed system, there was a further marked increase in the PGF content of the caruncles, release of PGF into the utero-ovarian vein, and increased concentrations of PGFM in the jugular vein. The caruncles always contained more PGF than the intercaruncular area, and released more PGF and PGFM during incubation in vitro. In the progesterone+oestradiol group, there was good correlation between the PGF concentrations in simultaneous samples from the right and left utero-ovarian veins, and for all groups there was a high correlation between utero-ovarian PGF and peripheral PGFM concentrations. The caruncular epithelium of the progesterone-treated animals contained more lipid droplets than those of the other groups.

These data are consistent with a requirement for progesterone in activating 'prostaglandin synthetase' activity, and promoting PGF production, largely from the caruncles. After progesterone priming, the synthesis of PGF by the caruncles and PG release into the vascular system was increased further by oestradiol treatment, whereas oestradiol alone was without effect.

Oestrogenic activity of oestradiol-decanoate after oral administration to rodents

Oestradiol-decanoate, dissolved in arachis oil and orally administered to rodents, produces oestrogenic effects. Compared on a molecular basis the ester has 0.1-1.0 times the activity of ethinyl oestradiol, dependent on the species and the parameter studied. The effects of oestradiol-decanoate are less or absent when the oil is omitted. It is likely that absorption of the steroid ester takes place via the intestinal lymphatics in conjunction with the oil.

Fertility of norgestomet treated dairy heifers

Four studies are described involving 2573 Friesian heifers treated with norgestomet and oestradiol valerate to control the ovarian cycle. All treated animals were inseminated at fixed times following treatment. In study 1 insemination 48 and/or 60 hours after treatment resulted in a non-significant greater proportion of heifers becoming pregnant than at 48 X 72 hours. Large variations in fertility among farms were recorded in field trials of norgestomet (Searle) and oestradiol valerate. In study III the effect on fertility of nutrition, weight and body condition was studied. In section IV a pregnancy rate to fixed time insemination of 66-8 per cent of 500 heifers inseminated at 48 and 60 or at 48 and 72 hours after norgestomet/oestradiol valerate treatment was obtained. Heifers in study IV were fed a balanced ration designed to provide a predicted daily liveweight gain of 0-7 kg for a 12-week period starting six weeks prior to the date of insemination. The range of fertility was from 59-0 per cent to 85-7 per cent.

Effect of indomethacin on estrogen-induced luteolysis in the ewe

Three groups of 6 ewes were laparotomized on day 9 of an estrous cycle (estrus = day 0) and the corporà lutea (CL) were marked with India ink. Indwelling cannulae were inserted into the uterine horn adjacent to the CL in groups 2 and 3. Group 1 was injected intramuscularly (i.m.) with corn oil twice daily on day 9. Group 2 received 750 microng 17beta-estradiol (E2) i.m. twice daily on day 9 plus intrauterine injections of indomethacin (INDO) vehicle on days 9 through 13. Group 3 received in the same estrogen treatment plus the injection of 20 mg INDO twice daily on days 9 through 13. Jugular venous samples were taken once daily on days 9 through 14 for progesterone analysis. At re-laparotmy on day 14, the ovaries were examined for new ovulations, and the ovary bearing the marked CL was removed. Results showed that E2 induced premature luteal regression as indicated by decreased CL weights and plasma progesterone levels. INDO when given in conjunction with E2 effectively blocked the luteolytic action of E2. These results suggest that the luteolytic action of E2 is mediated via increased prostaglandin secretion and release from the uterus.

Morphology, growth characteristics and oestrogen-binding capacity of DMBA-induced mammary tumours from ovariectomized rats

The morphology of 20 mammary adenocarcinomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) in Sprague-Dawley rats was compared with their growth characteristics and oestrogen-binding capacity following ovariectomy. The capacity to bind (3H)oestradiol-17B did not appear to be related to the growth characteristics, time of appearance after DMBA administration, or time between ovariectomy and assay for specific oestrogen-binding proteins. Furthermore, different tumours appeared to have oestrogen-binding capacities unrelated to the percentage of neoplastic cells within the tumour, amount of inflammation, mast cell infiltration, or the presence of fluid-filled cysts. The only morphological features which appeared to be correlated with oestrogen-binding capacity were the number of mitoses and the lipid content of the tumour; that is, the oestrogen-binding capacity tended to be lower in tumours with moderate or large numbers of mitoses and in tumours with much lipid in the epithelial cells. Six of the 19 adenocarcinomas found prior to sacrifice either continued growing or remained static following ovariectomy, while the others underwent regression. In 5 of the regressing tumours a new growth phase was observed, usually beginning 2 months after ovariectomy. Tumours other thus osteosarcoma as well as fibroadenomas and Zymbal-gland tumours.

Binding of [3-H]estradiol by brain cell nuclei and female rat sexual behavior: inhibition by antiestrogens

The antiestrogens MER-25, CI-628, and nafoxidine inhibit the uptake of [3H]-estradiol in whole homogenates and isolated cell nuclei tissues and the pituitary, and inhibit estradiol-induced female sexual behavior. The antiestrogens were injected intraperitoneally 2 h prior to an intravenous injection of [3H]estradiol, and the animals were killed 2 h after the estradiol. CI-628 reduces radioactivity in whole homogenates and isolated cell nuclei of cerebral cortex, hypothalamus, preoptic area -septum and pituitary. Nafoxidine reduces uptake in cell nuclei of the hypothalamus, preoptic area-septum and pituitary. In this paradigm, MER-25 inhibited uptake only in the pituitary. In the analogous behavioral experiments, with antiestrogens injected 2 h prior to an intravenous injection of unesterified estradiol, CI-628 and nafoxidine totally inhibited lordosis responding. MER-25 shows no inhibition of behavior in this paradigm. However, when MER-25 is injected 12 h prior to the estradiol, it inhibits retention of [3H]estradiol at 2 h in brain and pituitary cell nuclei, and lordosis responding is also inhibited. Additionally, the antiestrogens can apparently displace previously bound [3H]estrdiol. When the antiestrogens are injected 2 h prior to an injection of [3H]estradiol, MER-25, CI-628 and nafoxidine all show greater inhibition of nuclear estradiol retention at 12 h after the [3H]estradiol injection than 2 h. Analogously, when CI-628 is injected 2 h after an intravenous injection of [3H]estradiol, it displaces most of the radioactivity present in hypothalamic-preoptic area nuclei at 12 h after the estradiol injection. These results indicate that antiestrogens can prevent or reverse the nuclear concentration of estradiol in brain cells and are consistent with a role of the cell nucleus in the induction of estrous behavior by estradiol.

Potent inhibitory effect of a new antiestrogen (RU 16117) on the growth of 7,12-dimethylbenz[a]anthracene-induced rat mammary tumors

At the daily dose of 24 mug for a period of 4 weeks, RU 16117 (11alpha-methoxyethinyl estradiol), a new antiestrogen, led to 65% reduction of the number of already established dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in female Sprague-Dawley rats. Not only the tumor number but also the tumor size was reduced by RU 16117 in a manner similar to that seen after ovariectomy. The absence of an inhibitory effect of doses of 0.1 to 12.5 mug 17beta-estradiol (E2) per day, a dose-range which covers the low estrogenic activity of the RU 16117 doses used, suggested that the inhibitory effect of RU 16117 was not due to its estrogenic activity. Decreased levels of receptors for E2, progesterone, and prolactin were found in the tumors remaining after ovariectomy; treatment with the dose of RU 16117 sufficient to inhibit tumor growth (24 mug) had a similar inhibitory effect on the levels of E2 and prolactin receptors. These data suggested that a reduction of hormone receptor levels in the tumor tissue could be a mechanism by which RU 16117 acts as a potent inhibitor of the growth of DMBA-induced mammary carcinoma.

Implantation of pure crystalline pellets of estradiol for conception control

Estradiol pellet implantation for contraception offers another alternative in conception control. The occurrence of only two pregnancies in 1,668 cycles (Pearl index: 1,42) reflects its efficacy. The advantages over oral contraceptives are: (1) absence of gastrointestinal symptoms, (2) minimal untoward effects, (3) no patient failure, and (4) convenience. Progressive stepdown in dose reduces the total amount of steroid used in long-term contraception. Contraceptive effect may not occur during the first month of implantation; adequate precaution should be taken. Because of the efficacy, minimal untoward side effects, and excellent patient acceptability, this regimen may be considered for contraception in developing countries and when other modalities are contraindicated.