The agonistic-antagonistic properties of clomiphene: a review

Infertility, ovulation induction treatments and the incidence of breast cancer--a historical prospective cohort of Israeli women

CONTEXT

Ovulation induction drugs may be associated with increased breast cancer risk. Results so far have been inconclusive.

OBJECTIVE

To evaluate the association between infertility, exposure to ovulation induction drugs and the incidence of breast cancer.

DESIGN

Historical prospective cohort and nested case-control study.

SETTING

Institutional practice

PATIENTS

About 5,788 women attending five infertility centers in Israel between 1964 and 1984.

INTENTION

Abstracting of medical records and telephone interviews.

MAIN OUTCOME MEASURE

Breast cancer incidence was determined through linkage with the National Cancer Registry database. Standardized incidence ratios (SIRs) and 95% confidence intervals were computed by comparing the observed to the expected cancer rates in the general population. In addition, a nested case-control study within the cohort was performed with interviews of breast cancer cases and two matched controls.

RESULTS

The study cohort included 120,895 women years of follow-up. Compared to 115.2 expected breast cancer cases, 131 cases were observed (SIR = 1.1; 95% CI 0.9-1.4). Risk for breast cancer was significantly higher for women treated with clomiphene citrate (SIR = 1.4; 95% CI 1.0-1.8). Similar results were noted when comparisons were carried out between treated and untreated women, and when multivariate models were applied. In the nested case-control study, higher cycle index (OR = 2.2; 95% CI 1.0-4.8) and treatment with clomiphene citrate (OR=2.7; 95% CI 1.3-5.7) were associated with higher risk for breast cancer.

CONCLUSION

Infertility and usage of infertility drugs in general are not associated with increased risk for breast cancer. However, for infertile women treated with clomiphene citrate, breast cancer risk is elevated.

Time of initiation of clomiphene citrate and pregnancy rate in polycystic ovarian syndrome

OBJECTIVE

To investigate whether the timing of clomiphene citrate (CC) administration affects hormonal levels, follicular growth, endometrial thickness, and ovulation and pregnancy rates in women with polycystic ovarian syndrome (PCOS).

METHODS

Of the 78 infertile women with PCOS who participated in this prospective, double-blind, randomized clinical trial, 37 collectively underwent 71 cycles of CC (100 mg/day) on days 1 through 5 of the menstrual cycle (group 1) and 41 collectively underwent 73 cycles of CC at the same concentration on days 5 through 9 (group 2). Hormonal levels, follicular growth, endometrial thickness, and ovulation and pregnancy rates were compared.

RESULTS

The mean number of follicles and the maximum follicular size were greater in group 2. However, ovulation rates were 72.8% in group 1 and 70.8% in group 2 (P=.78), and pregnancy rates were 40.5% in group 1 and 19.5% in group 2 (P=.04).

CONCLUSION

Treatment with CC is associated with higher rates of pregnancy if started early (days 1-5) in the menstrual cycle.

Estradiol protects clomiphene citrate–induced apoptosis in ovarian follicular cells and ovulated cumulus–oocyte complexes

OBJECTIVE

To determine whether clomiphene citrate (CC) reduces E(2) level in the ovary and circulation and induces apoptosis in ovarian follicular cells and ovulated cumulus-oocyte complexes (COCs). If yes, to determine whether E(2) coadministration could protect against these adverse effects of CC.

DESIGN

A controlled prospective study.

SETTING

Laboratory research setting.

ANIMAL(S)

Ninety sexually immature female rats that were 24-25 days of age.

INTERVENTION(S)

The immature female rats were injected with a single dose of 10 IU of pregnant mare serum gonadotropin. After 48 hours, 10 IU of hCG along with 10 mg of CC per kilogram of body weight, with or without 2.0 mg of E2 per kilogram of body weight were coadministered. After 16 hrs, the rats were killed; COCs were collected from oviduct and ovaries were isolated.

MAIN OUTCOME MEASURE(S)

Number of superovulated COCs, oocyte morphology, E2 level in ovary and serum, histology of ovary, DNA fragmentation, and bax protein expression in ovary and COCs.

RESULT(S)

The number of COCs and E2 level in ovary and serum were reduced, whereas membrane blebbing in oocytes, bax protein expression, and DNA fragmentation in ovarian follicular cells and ovulated COCs were induced after CC treatment. These adverse effects of CC were protected against if animals were coadministered with E2.

CONCLUSION(S)

Clomiphene citrate-induced apoptosis in ovarian follicular cells (probably granulosa cells), thereby reducing E2 level in ovary and circulation that might have resulted in poor development and maturation of oocytes leading to reduced ovulation.

Psychological side-effects of clomiphene citrate and human menopausal gonadotrophin

OBJECTIVE

This study evaluated the psychological side-effects of clomiphene citrate (CC) and hMG in women undergoing fertility treatment.

METHOD

This study was a cross-sectional, self-report survey of 454 women at various stages of treatment for infertility. At the time of study, 139 women had not taken fertility drugs and 315 women had taken one or more cycles of CC or hMG. All subjects were asked to complete the State-Trait Anxiety Inventory (STAI). Women taking CC or hMG were also asked to complete a self-administered questionnaire on the side-effects of their medications.

RESULT(S)

In the CC group (n = 162) and hMG group (n = 153), 77.8% (126 of 162) and 94.8% (145 of 153) reported at least one side-effect, respectively. Irritability, mood swings, feeling down, and bloating had high frequencies in both CC and hMG groups, with a higher mean number of side effects reported in the hMG group (4.4 +/- 3.7 for the CC group and 6.8 +/- 3.7 for the hMG group, p < 0.001). There was no significant difference among the CC, hMG and no medication groups for mean state and trait anxiety scores. However, there were significant differences among the three side-effect groups (those who reported 1 to 4, 5 to 7, and more than 7 side-effects) for the mean scores of state (df = 2, F = 8.7, p < 0.001) and trait (df = 2, F = 11.9, p < 0.001) anxiety in women taking fertility drugs.

CONCLUSION(S)

Women taking CC or hMG reported high frequencies of psychological side-effects, and should be advised of these before treatment.

Differential expression of endometrial integrins and progesterone receptor during the window of implantation in normo-ovulatory women treated with clomiphene citrate

OBJECTIVE

To assess the effect of clomiphene citrate (CC) on endometrial epithelial integrins and P receptors (PR) during the window of implantation.

DESIGN

Controlled, prospective, clinical study.

SETTING

Teaching hospital and university research laboratory.

PATIENT(S)

Thirty-one fertile, normo-ovulatory women participated in this trial. Thirteen women exhibited a CC-stimulated cycle with 50 mg on days 5-9, and 18 women with spontaneous menstrual cycles served as controls.

INTERVENTION(S)

Endometrial biopsies in the midluteal phase.

MAIN OUTCOME MEASURE(S)

Immunohistochemical determination and endometrial cellular localization of alpha1, alpha v, beta3, and alpha4 epithelial integrins and PR during the window of implantation. The staining intensity was assessed by a semiquantitative index (HSCORE) and compared by nonparametric Mann-Whitney test.

RESULT(S)

Higher plasma levels of P and E2 and delayed histologic dating of the endometrium (38%) were features of CC-treated women. In addition, a low epithelial beta3 integrin expression and persistent PR were observed in glandular epithelial cells of "out-of-phase" endometrial biopsies from CC-treated women. In contrast, in "in-phase" biopsies, neither epithelial PR nor beta3 integrin were different from spontaneous control cycles. There was no difference in the expression of alpha1, alpha v, and alpha4 between the groups studied.

CONCLUSION(S)

The administration of clomiphene produces aberrant endometrial beta3 integrin expression in conjunction with a failure in the down-regulation of PR during the window of implantation in a significant number of normo-ovulatory women, notwithstanding the higher plasma P levels. Therefore, CC might affect the expression of endometrial receptivity markers.

Monitoring plasma concentrations to individualize treatment with clomiphene citrate

OBJECTIVE

Recent reports have indicated that a number of individual patient characteristics are responsible for the success or failure of clomiphene citrate treatment. However, a priori individualization of doses in different patients has not been investigated. We examined the thesis that wide variability in the metabolism of the active component (zuclomiphene) contributes to variability in response.

METHODS

The dose-response relationship of clomiphene was established from a meta-analysis of data from 13 published reports. Limited data relating plasma drug concentrations to treatment outcome were examined to determine whether insufficient systemic exposure at a fixed dosage might contribute to therapeutic failure.

RESULTS

A fixed-dosage regimen of 50 mg clomiphene per day is likely to cause ovulation in only 46% of patients; subsequent increment in dosage increases the number of responders but at the expense of considerable delay in individualization of treatment. Case reports indicated that dosage based on plasma drug concentration monitoring could improve patient management, and an algorithm is proposed to facilitate treatment.

CONCLUSIONS

Prospective studies of clomiphene citrate should be performed to confirm the hypothesis that the monitoring of plasma zuclomiphene concentrations can significantly accelerate dose individualization and improve the therapeutic outcome with this "orphan" drug.

Embryo/fetal toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in rats and rabbits

BACKGROUND

The purpose of this study was to evaluate the effects of lasofoxifene, a selective estrogen receptor modulator (SERM), on rat and rabbit fetal development.

METHODS

Lasofoxifene was administered orally to rats (1, 10, 100 mg/kg) between gestation days (GD) 6-17, and in rabbits (0.1, 1, 3 mg/kg) between GD 6-18. Maternal body weight and food consumption were monitored throughout pregnancy. Fetuses were delivered by Cesarean section on GD 21 in rats, and GD 28 in rabbits, to evaluate fetal viability, weight, and morphology. Drug concentrations in maternal plasma were measured in a separate cohort of animals at several time points commencing on GD 17 (rats) and 18 (rabbits). On GD 18 (rat) and GD 19 (rabbit) drug concentrations were measured in maternal plasma and in fetal tissue 2 hr post dosing to determine the fetal to maternal drug ratio.

RESULTS

In rats, there were dose-related declines in maternal weight gain and food consumption. Post implantation loss was significantly increased at dosages of 10 and 100 mg/kg, and the number of viable fetuses was decreased at 100 mg/kg. The placental weights increased, whereas fetal weights decreased in a dose-dependent manner. Lasofoxifene-related teratologic findings were noted at 10 and 100 mg/kg and included imperforate anus with hypoplastic tails, dilatation of the ureters and renal pelvis, misaligned sternebrae, hypoflexion of hindpaw, wavy ribs, and absent ossification of sternebrae. In rabbits, neither maternal weight gain nor food consumption were affected during treatment. Between GD 26-28, there was a dose-dependent increased incidence of red discharge beneath the cages. At 1 and 3 mg/kg, resorptions and post-implantation loss increased. There were no significant external or visceral effects, but 3 mg/kg there was an increased incidence of supernumerary ribs. Although the maternal plasma Cmax and AUC(0-24) were dose-dependent, the exposures in the rat were many orders of magnitude greater than in the rabbit even for the same 1 mg/kg dose. The single time point fetal/maternal drug ratio was higher in the rat (1.3-0.78) than in the rabbit (0.21-0.16).

CONCLUSION

In general, both maternal and fetal effects of lasofoxifene were similar to those reported with other SERMs. Although the incidence or severity of these effects was, in some instances, greater in the rat than in the rabbit, the doses and the resultant maternal and fetal exposures were many orders of magnitude higher in the rat, suggesting the rabbit to be more sensitive to the toxicological effects of lasofoxifene.

Reproductive toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in female rats

BACKGROUND

Lasofoxifene is a nonsteroidal selective estrogen receptor modulator (SERM). With high affinity to the alpha and beta human estrogen receptors and greater potency than other SERMs, lasofoxifene is potentially a superior treatment for postmenopausal osteoporosis. In light of the known effects of estrogen-modulating compounds on female reproductive indices, two studies were conducted to evaluate the effects of lasofoxifene on female rat cyclicity, reproduction, and parturition.

METHODS

One study evaluated effects of lasofoxifene on estrous cyclicity, and the second study assessed effects on implantation and parturition. In the cyclicity study, lasofoxifene was administered to female rats at doses of 0.1, 0.3, and 1.0 mg/kg/day for 14 consecutive days. After treatment, there was a 3-week reversibility phase followed by a mating phase. In the implantation study, lasofoxifene was administered to pregnant female rats at doses of 0.01, 0.03, and 0.1 mg/kg/day for 7 consecutive days (gestation day [GD] 0-6). Some animals were euthanized on GD 21, and the remainder of the group was allowed to deliver the F1 generation. Several developmental indices were evaluated in the F1 pups through post-natal day (PND) 21.

RESULTS

In the cyclicity study, all lasofoxifene-treated females were anestrous by Study Day 7 (1.0 mg/kg) or 9 (0.3 and 0.1 mg/kg). The reversibility phase resulted in restoration of normal estrous cycles by the end of 1 (0.1 mg/kg) or 2 weeks (0.3 and 1.0 mg/kg). During the mating phase, no adverse effects occurred in pregnancy success or reproductive parameters. In the implantation study, all doses of lasofoxifene increased pre- and post-implantation losses, increased gestation length, and reduced litter size. None of the developmental parameters measured on the F1 generation was adversely affected.

CONCLUSION

Lasofoxifene reversibly altered the estrous cycle and inhibited implantation, consistent with what would be expected from a member of the SERM class.

Clomiphene citrate in the twenty-first century

Clomiphene citrate is the drug most commonly prescribed for ovulation induction. It is the first choice medication in normogonadotrophic oligo/amenorrhoeic infertility (WHO group 2), essentially associated with polycystic ovaries. Anovulatory women who are responsive to clomiphene citrate should be treated for at least six cycles and the treatment should probably be limited to a maximum of 12 cycles. It is necessary to monitor at least the first cycle with ultrasonography because of the risk of multiple pregnancy and the variable response of patients to different doses of clomiphene. In addition, the risk of ovarian hyperstimulation syndrome should not be underestimated. More triplets and higher order pregnancies result from ovulation induction than from in vitro fertilization, and multiple pregnancy has many risks for both mother and babies. The role of empirical clomiphene in the treatment of unexplained infertility is debatable and the present data are inconclusive. Obesity, hyperandrogenaemia and insulin resistance are important factors in clomiphene-resistant patients. Failure to ovulate in response to clomiphene has been approached by either medical or surgical treatment. An effective alternative medical treatment is gonadotrophin injections. Treatment with metformin and the new generation of insulin-sensitizing drugs is under evaluation. The most widely used surgical treatment today is laparoscopic ovarian drilling, which appears to be as effective as gonadotrophin therapy.

Use of an aromatase inhibitor for induction of ovulation in patients with an inadequate response to clomiphene citrate

OBJECTIVE

To use aromatase inhibition for induction of ovulation in women in whom clomiphene citrate (CC) treatment was unsuccessful.

DESIGN

Prospective trial in infertility patients treated with CC.

SETTING

Two tertiary-referral infertility clinics associated with the Division of Reproductive Sciences, University of Toronto.

PATIENT(S)

Twelve patients with anovulatory polycystic ovary syndrome (PCOS) and 10 patients with ovulatory infertility, all of whom had previously received CC with an inadequate outcome (no ovulation and/or endometrial thickness of < or =0.5 cm).

INTERVENTION(S)

The aromatase inhibitor letrozole was given orally in a dose of 2.5 mg on days 3-7 after menses.

MAIN OUTCOME MEASURE(S)

Occurrence of ovulation, endometrial thickness, and pregnancy rates.

RESULT(S)

With CC treatment in patients with PCOS, ovulation occurred in 8 of 18 cycles (44.4%), and all ovulatory cycles for the women included in this study had endometrial thickness of < or =0.5 cm. In 10 ovulatory patients, 15 CC cycles resulted in a mean number of 2.5 mature follicles, but all cycles had endometrial thickness of < or =0.5 cm on the day of hCG administration. With letrozole treatment in the same patients with PCOS, ovulation occurred in 9 of 12 cycles (75%) and pregnancy was achieved in 3 patients (25%). In the 10 patients with ovulatory infertility, letrozole treatment resulted in a mean number of 2.3 mature follicles and mean endometrial thickness of 0.8 cm. Pregnancy was achieved in 1 patient (10%).

CONCLUSION(S)

Oral administration of the aromatase inhibitor letrozole is effective for ovulation induction in anovulatory infertility and for increased follicle recruitment in ovulatory infertility. Letrozole appears to avoid the unfavorable effects on the endometrium frequently seen with antiestrogen use for ovulation induction.

Cyclic changes in serum levels of insulin-like growth factor binding protein-1 in women treated with clomiphene citrate and tamoxifen

In order to investigate the cyclic changes of serum insulin-like growth factor-I (IGF-I), IGF binding protein-1 (IGFBP-1) and IGFBP-3 levels in menstrual cycles treated with or without antiestrogens (clomiphene citrate and tamoxifen), we treated 24 young women having irregular menstrual cycles with either clomiphene citrate (100 mg/day) (n = 12) or tamoxifen (60 mg/day) (n = 12) from the 5th to the 9th day of the menstrual cycle. Without antiestrogens, 12 women with regular menstrual cycles were recruited as controls. There was a preovulatory (day 13) peak of circulating IGFBP-1 in women treated with or without antiestrogens. A significant concomitant increase in serum estradiol was also observed on day 13 of the menstrual cycle in subjects treated with clomiphene citrate and in controls. However, no significant elevation in preovulatory estradiol was detected in women treated with tamoxifen. In clomiphene citrate and control groups, a significant positive correlation was found between circulating IGFBP-1 and estradiol, and between serum levels of IGFBP-1 and inhibin A at the preovulatory stage (on day 13). In contrast, no such association was observed in the tamoxifen group. Unlike cyclic changes in circulating IGFBP-1, serum concentrations of IGF-I and IGFBP-3 remained unchanged throughout the menstrual cycle in all groups. In conclusion, the preovulatory peak of circulating IGFBP-1 can be induced in cycles treated with both clomiphene citrate and tamoxifen. In addition, a significant positive correlation between estradiol, inhibin A and IGFBP-1 at the preovulatory stage indicates that IGFBP-1 may also reflect follicular development and may further be used as an additional indicator to monitor folliculogenesis under clomiphene citrate treatment.

Clomiphene citrate-induced perturbations during meiotic maturation and cytogenetic abnormalities in mouse oocytes in vivo and in vitro

OBJECTIVE

To determine if clomiphene citrate induces temporal perturbations during meiotic maturation and aneuploidy in mouse oocytes.

DESIGN

A controlled dose study involving mouse oocytes in vivo and in vitro.

SETTING

Clinical and academic research setting in a university medical center.

INTERVENTION(S)

Oocytes were obtained after superovulation and from mature follicles.

MAIN OUTCOME MEASURE(S)

Cytogenetic analysis of oocytes for aneuploidy, premature centromere separation, premature anaphase, and single chromatids, and the frequencies of metaphase I and diploid oocytes.

RESULT(S)

Clomiphene citrate resulted in a decrease in the number of ovulated oocytes and a significant (P<.05) increase in hyperploidy at 100 mg/kg in vivo. In vitro, 5.0 microg/mL of clomiphene citrate significantly (P<.05) increased hyperploidy and reduced the proportion of metaphase I oocytes.

CONCLUSION(S)

These findings suggest that clomiphene citrate has the potential for inducing aneuploidy in mouse oocytes both in vivo and in vitro and that the rate of oocyte maturation is altered after clomiphene exposure in vitro. Additional data are needed to support the results of this study.

Clomiphene-induced severe hypertriglyceridemia and pancreatitis

Clomiphene has been available for clinical use since 1960 and has been successfully used to aid fertility in women with certain anovulatory disorders. It is a synthetic estrogen analog, of the triphenylethylene derivative group, and its biochemical structure is similar to that of tamoxifen. Estrogen and tamoxifen lower total and low-density lipoprotein cholesterol and increase triglyceride and high-density lipoprotein cholesterol levels. In patients with baseline hypertriglyceridemia, these agents can induce severe hypertriglyceridemia and pancreatitis. The actions of clomiphene on lipid metabolism have not been studied, and to our knowledge, no cases of severe hypertriglyceridemia related to the use of clomiphene have been described. We report the case of a woman who developed 2 episodes of clomiphene-induced hypertriglyceridemia and pancreatitis while receiving this drug for treatment of infertility. Given the striking structural similarity between clomiphene and tamoxifen, it is likely that clomiphene is capable of inducing severe hypertriglyceridemia in patients with certain underlying lipid disorders by a mechanism similar to that of tamoxifen.

Expression of glucosamine trisaccharides on the rat uterine surface is altered by clomiphene citrate

We have studied histochemically the effects of clomiphene citrate on the expression of oligosacchrides on the apical plasma membrane of uterine epithelial cells using the lectin Phytolacca americana. Ovariectomized sexually mature rats were given a single injection of either clomiphene in two concentrations or estradiol 17 beta or progesterone and were killed 24 hr later. Uterine tissue was labeled with Phytolacca americana conjugated with avidin and subsequently labeled with biotinalyted ferritin and prepared for transmission electron microscopy. Our results indicate that clomiphene and to a lesser degree progesterone significantly increased lectin binding. However, the increase was not as large as that observed with a single dose of estrodiol 17 beta. When the proportion of lectin positivity in relation to total membrane length was analyzed, treatment with clomiphene and progesterone did not have significantly different effects. Low dose clomiphene did not have a significant effect as compared with controls. Our data show that clomiphene has a dose-dependent adverse effect on lectin binding as compared with ovarian hormones. We suggest that these effects contribute to low pregnancy rates with clomiphene use.

Studies of protein binding to nonpolar solutes by using zonal elution and high-performance affinity chromatography: interactions of cis- and trans-clomiphene with human serum albumin in the presence of beta-cyclodextrin

High-performance affinity chromatography and zonal elution studies were used to examine the binding that takes place between the drug clomiphene and the protein human serum albumin (HSA). Equations were derived to describe the behavior of zonal elution experiments in which a solubilizing agent is present in the mobile phase to aid in the dissolution of a competing agent or injected analyte. These equations were then used to determine the association equilibrium constants for the clomiphene/HSA system, with beta-cyclodextrin being used as a complexation agent to improve the water solubility of cis- and trans-clomiphene without affecting the nature of their binding to HSA. It was found in these studies that both cis- and trans-clomiphene have 1:1 interactions at a common binding region on HSA (association constants at pH 7.4 and 37 degrees C: cis, 7.5 x 10(6) M-1; trans, 1.3 x 10(6) M-1). Further competition experiments between cis- or trans-clomiphene and various site-selective probes indicated that the clomiphene-binding region is the same as the proposed tamoxifen site of HSA. The approach and equations used within this report are general ones that can be applied to zonal elution studies of other solute-ligand systems in which one or more of the test components have limited solubility in the desired mobile phase.

The selective estrogen receptor modulator, raloxifene: segment II studies in rats and rabbits

Raloxifene is a nonsteroidal, selective estrogen receptor modulator developed by Eli Lilly and Company primarily as a therapeutic agent for postmenopausal osteoporosis. Two Segment II studies were conducted that examined maternal reproductive parameters and fetal outcome following gestational exposure to raloxifene. Pregnant CD rats (25/group) and New Zealand white rabbits (20/group) were dosed once daily by oral gavage with 0, 0.1, 1, or 10 mg/kg on Gestation Days (GD) 6 through 17 and 7 through 19, respectively. Maternal body weight and food consumption were monitored throughout pregnancy. Caesarean sections were performed on GD 20 and GD 28 for rats and rabbits, respectively, to evaluate fetal viability, weight, and morphology. In rats, maternal body weight, body weight gain, and food consumption were reduced in all raloxifene treatment groups. Fetal viability was depressed in the 10-mg/kg group and was often associated with signs of hemorrhaging from the vagina. Fetal growth retardation was indicated in the 1- and/or 10-mg/kg groups by increased incidences of fetal runts and the developmental deviations, wavy ribs and kidney cavitation. There was no evidence of treatment-related malformations in rat fetuses. In rabbits, depressions in body weight gain and food consumption occurred in the 10-mg/kg group, and a single abortion occurred in the 1-mg/kg group. Fetal viability and weights were not affected in any of the raloxifene treatment groups. The overall proportions of fetuses with malformations, deviations, or variations were not affected by treatment with raloxifene; however, one fetus each from the 0.1-, 1-, and 10-mg/kg groups had incomplete closure of the interventricular septum. Therefore, maternal and fetal no-effect levels were not obtained in this study of raloxifene.

The selective estrogen receptor modulator, raloxifene: a segment II/III delivery study in rats

Raloxifene is a nonsteroidal, selective estrogen receptor modulator developed by Eli Lilly and Company as a therapeutic agent for postmenopausal osteoporosis. Raloxifene was administered orally by gavage at doses of 0, 0.1, 1, or 10 mg/kg/d to female CD rats (25/group) on Gestation Day 6 (GD 6) through Postpartum Day 20 (PD 20). Females were allowed to deliver and maintain their progeny until PD 21. All dead pups and pups culled on PD 1 were given internal and external examinations. One pup/sex/litter was assigned to each of the following assessment groups: 1) the primary pair for the F1 generation study, in which survival, growth, development, behavior, indicators of sexual maturation, and reproductive performance were evaluated; 2) terminal necropsy evaluations at PD 21; 3) terminal necropsy evaluations at 60 d of age; and 4) assessments of immune function at 5 to 6 weeks of age. At termination on PD 21, 60, or approximately 140, a necropsy was performed; crown rump and tibia lengths were measured; pituitary weights were taken; and a portion of the anterior pituitary was retained for growth hormone, luteinizing hormone, and prolactin content determinations (control and 10-mg/kg groups only). The remainder of the pituitary and reproductive tissues were retained for histologic evaluations. Dose-related depressions in maternal body weight and food consumption occurred during gestation. Mean gestation length was increased at 1 and 10 mg/kg. Delayed, extended, and/or disrupted parturition occurred in dams given 10 mg/kg, which resulted in a high incidence of maternal morbidity and/or death, increased numbers of dead pups, and the survival of only 66% of live pups to PD 21. Progeny body weights were not decreased at birth, but were depressed progressively in a dose-related manner during the 3-week lactation period. Negative geotaxis and incisor eruption were apparently accelerated in the 1- and 10-mg/kg groups, but eye opening was delayed at 10 mg/kg. Postweaning activity levels, auditory startle, and passive avoidance performance were not affected in the raloxifene groups. Dose-related decreases in spleen cellularity and thymus weights occurred in both sexes, but immune system function, as measured by splenic natural killer cell activity and antibody response to sheep red blood cells, was not affected. Postweaning body weights and growth parameters, as well as pituitary hormone content, were affected in both an age- and sex-specific manner. Preputial separation was not affected, but vaginal patency occurred ca 2 d earlier than controls in females from the 10-mg/kg group. Estrous cycles of the F1 females were not affected during the first two weeks after vaginal opening, but were disrupted at 12 to 14 weeks of age in the 10-mg/kg group. These females showed poorer mating and fertility indices, and litter size was reduced in the two females that were pregnant. Histologically, reproductive organs were not affected in males at any age or in females at PD 21. At PD 60, vaginal mucification occurred in females from the 0.1- and 1-mg/kg groups. At PD 140, the only finding was a high rate of uterine hypoplasia in the 10-mg/kg group, and this finding occurred in the absence of any concomitant ovarian or vaginal changes. These reproductive and developmental findings are consistent with estrogen antagonist activity of raloxifene.

E-cadherin and its messenger ribonucleic acid in periimplantation phase human endometrium in normal and clomiphene-treated cycles

OBJECTIVE

The purpose of this investigation was to determine whether treatment with clomiphene citrate, which is estrogenic and antiestrogenic, affects the expression of the cell adhesion molecule E-cadherin in human periimplantation phase endometrium.

STUDY DESIGN

Five healthy women were studied for two cycles each, a control and a treated (clomiphene 50 mg daily, days 5 through 9) cycle. A biopsy specimen of endometrial tissue was studied (8 to 10 days post luteinizing hormone surge) for immunohistochemical localization, Western analysis of E-cadherin with use of a highly specific monoclonal antibody to human E-cadherin, and determination of messenger ribonucleic acid for E-cadherin by reverse transcription-polymerase chain reaction by use of oligonucleotide primers specific to E-cadherin and amplifying a 432 bp fragment.

RESULTS

Luteal phase plasma progesterone levels were significantly higher in clomiphene cycles. E-cadherin was immunocytochemically present in endometrium of control and treated cycles with no apparent difference in staining intensity. Western blots revealed the presence of E-cadherin. It was relatively more abundant in clomiphene-treated than control cycles but not significantly different. The message for E-cadherin gene is expressed in endometrium of control (n = 5) and clomiphene cycles (n = 4).

CONCLUSIONS

E-cadherin and its gene transcripts are expressed in periimplantation phase endometrium and are not significantly affected by clomiphene treatment.

The selective estrogen receptor modulator, raloxifene: reproductive assessments following premating exposure in female rats

Raloxifene HCl is a nonsteroidal, selective estrogen receptor modulator developed as a therapeutic agent for postmenopausal osteoporosis. Two studies were conducted that examined the effects of premating exposure to raloxifene HCl. In the first study, adult female CD rats (20/group) were given diets containing 0, 0.01, or 0.1% raloxifene (providing an average of 0, 6, or 63 mg/kg/d, respectively) for 2 weeks, after which the treated diets were replaced with control diet. Following a 2-week period without treatment, each female that had displayed at least three conversions in vaginal cytology from cornified cells to leukocytes was cohabited for 1 to 2 d with an untreated male as she entered proestrus. Females were killed at midgestation and examined for evidence of pregnancy. In the second study, adult female CD rats (40/group) were given oral gavage doses of raloxifene (0, 0.1, 1, or 10 mg/kg/d) for 4 weeks. Immediately or following a 2-week period without treatment, 20 females/group were cohabited with untreated males (1:1) for up to 3 weeks. The females were allowed to deliver and rear their offspring until Postpartum Day 21. Progeny survival, growth, and development were evaluated. Maternal body weight, body weight gain, and food consumption were depressed in all raloxifene treatment groups. Doses > or =1 mg/kg caused disruptions in estrous cycles. In Study 1, 90% of the females treated with raloxifene resumed normal cycling, and fertility was not significantly affected. Although there were no statistically significant differences in time-to-mating, fertility, or liveborn indices in Study 2, females in the 10-mg/kg immediate-cohabitation group had slightly increased gestation lengths and smaller litter sizes. Progeny from these litters were larger on Postpartum Day 1 and had advanced incisor eruption and eye opening. In addition, slight delays were seen in physical landmark appearance in the 0.1- and 1-mg/kg immediate-cohabitation groups and in the 1- and 10-mg/kg delayed-cohabitation groups. Progeny viability, growth, and negative geotactic performance were not adversely affected. In these studies of maternal premating exposure to raloxifene, findings were consistent with established pharmacologic activity of the test chemical. Reproductive effects (disrupted estrous cycles and decreased litter size) occurred at doses > or =1 mg/kg and were generally reversible. Effects on offspring were seen at doses > or =0.1 mg/kg, were of minor importance, and were resolved during the lactation period.

Oestrogenic effects of ICI 182,780, a putative anti-oestrogen, on the secretion of oxytocin and prostaglandin F2 alpha during oestrous cycle in the intact ewe

The effect of ICI 182,780, oestrogen antagonist, on the concentration of oxytocin and uterine PGF2 alpha was investigated in intact Border Leicester Merino cross ewes during the late oestrous cycle. Twelve cyclic ewes (n = 6 per group) were randomly assigned to receive, at 6 h intervals, intra-muscular injection of either peanut oil or ICI 182,780 (1.5 mg kg-1 day-1) in oil for 2 days, starting at 1900 h on day 13 until 1300 h on day 15 post-oestrus. Hourly blood samples were collected via a jugular catheter from 0800 h on day 14 for 37 h and then daily over days 16, 17 and 18 post-oestrus. Peripheral plasma concentrations of oxytocin, the metabolite of prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, (PGFM) and progesterone were measured by radioimmunoassay. All ewes treated with ICI 182,780 exhibited functional luteal regression as indicated by a marked reduction in plasma progesterone concentrations to less than 1000 pg/ml over the period of 18-36 h during sampling period on days 14 and 15 of the oestrous cycle. In five of six vehicle-treated ewes, progesterone concentrations declined between day 16 and day 18 post-oestrus. In the remaining control ewe, progesterone concentrations reach less than 1000 pg/ml within 36 h of the commencement of the sampling period. During the frequent sampling period, the number of oxytocin pulses in the ICI 182,780 treated ewes was significantly higher compared to control ewes (2.7 +/- 0.3 vs. 0.8 +/- 0.3). The mean amplitude of oxytocin pulses observed was also greater (70.4 +/- 19.5 pg/ml) in ewes treated with ICI 182,780, but was not significantly different from the control ewes (33.5 +/- 12.9 pg/ml). Oxytocin pulses may however have occurred following the initial two ICI 182,780 injections but before commencing blood sampling. The oxytocin pulses were detected at a mean of 3.2 +/- 0.2 h following each injection with ICI 182,780 during blood sampling. In the ICI 182,780-treated ewes, the pulsatile pattern of plasma PGFM in jugular blood samples over the 37 h sampling period on days 14 and 15 post-oestrus had a higher amplitude (512.9 +/- 158.9 vs 121.7 +/- 78.7 pg/ml) and pulse area (618.1 +/- 183.3 vs 151.5 +/- 102.9 (ph/ml)tau) compared to the vehicle-treated ewes (P < 0.05) respectively.. The average number of PGFM pulses observed per ewe was 3.0 +/- 0.7 in the ICI 182,780-treated group and was significantly (P < 0.02) higher than the number of pulses (0.5 +/- 0.3) observed in ewes treated with vehicle alone. The PGFM pulses were detected at 4.2 +/- 0.6 h following each injection with ICI 182,780 during blood sampling. The percentage of PGFM pulses that occurred coincidently with significant elevation of oxytocin concentrations was 44.4% in ICI 182,780-treated compared to 66.6% in control ewes. We conclude that administration of oestrogen antagonist ICI 182,780 accelerated development of the luteolytic mechanism by enhancing pulsatile secretion of oxytocin and PGFM which suggests that ICI 182,780 acts as an agonist for oxytocin and prostaglandin f2 alpha release in intact ewes when administered at 1.5 mg/kg/day over day 13 to 15 post-oestrus.

Clinical uses of antiestrogens

An antiestrogen is a compound that blocks the action of estrogen. Most synthetic antiestrogens have agonistic or antagonistic activity depending on the tissue and the endogenous estrogen mileu. The triphenylethylene derivatives, clomiphene and tamoxifen, are the antiestrogens in greatest clinical use. Their biologic effects, clinical indications, and risks are reviewed. Novel antiestrogens which are beginning to be studied clinically include the benzothiophene derivative, raloxifene and the "pure" antiestrogens such as ICI 182,780. New clinical indications for existing compounds as well as the development of novel antiestrogens may lead to better treatment options for endocrine-dependent conditions.

Mechanisms of action of endocrine treatment in breast cancer

Endocrine treatment plays an important role in the therapy of breast cancer. While the basic mechanisms are understood, additional mechanisms may be of importance to their action and they may also contribute to the mechanism(s) of acquired resistance. Currently, several novel drugs are entering into clinical trials. Observations of the absence or presence of cross resistance to novel 'pure' steroidal antiestrogens and the non-steroidal tamoxifen may add important information to our understanding of the mechanisms of action of both classes of drugs. Similarly, exploration of different aromatase inhibitors in sequence or concert, as well as the combining of different endocrine treatment options may be warranted. Additionally, alterations in different biochemical parameters such as growth factors should not only be carefully explored in relation to treatment options but should also be followed during the course of treatment to asess alterations over time and in relation to the development of drug resistance.

The luteinizing hormone surge--the final stage in ovulation induction: modern aspects of ovulation triggering

OBJECTIVE

To compile updated information regarding gonadotropin secretion, specifically the physiology of the midcycle LH surge, in natural cycles and under various ovulation induction protocols.

DATA IDENTIFICATION AND SELECTION

Studies that deal with the clinical aspects of LH surge manipulation or substitution were identified through literature and Medline searches.

RESULTS

Three major regulatory factors have been identified as participants in the induction of the midcycle gonadotropin surge. These are hypothalamic GnRH secretion, ovarian and adrenal steroids, and less well-characterized ovarian peptide hormones. Gonadotropin-releasing hormone pulsatility is regulated by a complex mechanism that integrates multiple neurotransmitters and sex steroids. Estradiol plays a central role in the pituitary secretion of LH, which also is influenced by P concentrations. Gonadotropin surge attenuating factor also has been implicated in the regulation of timing and amplitude of the LH surge. Human chorionic gonadotropin is used extensively as a LH surrogate, but its use is associated with a number of disadvantages. Induction of an endogenous LH surge through use of the flare effect of GnRH analogues has been examined more recently and has been found to have several advantages. Recombinant human LH is in the final stages of clinical testing.

CONCLUSION

Although much is known about the physiology of the midcycle LH surge and its variations under different clinical conditions, new approaches to the induction or substitution of the LH surge currently are being examined and learned. The introduction of recombinant gonadotropins into clinical practice is likely to influence ovulation induction and IVF practice to a significant degree in the near future.

Adverse effects of fertility drugs

Ovulation-induction agents are commonly used in the treatment of infertility in patients with or without ovulatory disturbances. These agents include clomifene, bromocriptine, gonadotrophin preparations and gonadotrophin-releasing hormone (GnRH) and its analogues. Each agent is associated with its own specific adverse effects. Although many of these adverse effects are benign and self-limited, some, in particular those effects associated with gonadotrophins, may be life-threatening. Commonly noted adverse effects encountered with the use of pharmacological agents to treat infertility include the following. Clomifene has been associated with hot flushes, multiple gestation, visual disturbances, cervical mucus abnormalities and luteal phase deficiency. Similarly, most of the adverse symptoms associated with bromocriptine are short-lived, such as nausea and postural hypotension. On the other hand, gonadotrophin therapy, even when used appropriately, may lead to the ovarian hyperstimulation syndrome (which is occasionally life-threatening) and a high incidence of multiple gestation. Pulsatile GnRH therapy maybe accompanied by similar adverse effects to those of gonadotrophins, but with a far lower incidence. With regards to the long term safety of these medications, the relationship between fertility drugs and epithelial ovarian cancer is controversial, and causality has yet to be proven. Indeed, a working knowledge of the many adverse effects associated with these medications is essential to any physician prescribing ovulation induction agents, in order to ensure maximum patient safety, compliance and understanding.

Effect of anordiol on ovarian hormone secretion, ovulation, and uterine and vaginal responses in the immature rat

The purpose of this investigation was to determine the estrogenic and antiestrogenic activities of the potential contraceptive agent anordiol in the immature rat. A dose of 2.45 mumol of anordiol (AD), estradiol (E2), clomiphene citrate (CC), tamoxifen (TA), or the vehicle alone was administered to rats on the 25th and 29th days of age. Serum hormones were measured between 16:00 and 17:00 on days 30, 31, and 32; organ weights were determined on day 32. Anordiol and estradiol treatments significantly increased ovarian and uterine weight and serum LH concentrations, but CC and TA had no effect on these parameters. Vaginal cornification occurred before day 32 in all rats receiving anordiol or estradiol and in 3/5 and 4/5 rats receiving CC and TA, respectively, but not in control rats. Based on serum progesterone levels, ovulation was induced only in rats receiving anordiol or estradiol. All of the compounds tested significantly increased serum testosterone above levels in control animals, but both AD and E2 induced ovulation without a further increase in serum testosterone. We conclude that in the immature rat anordiol produces estrogenic responses in the vagina, uterus and in the hypothalamic-pituitary-ovarian axis, whereas TA and CC are estrogenic only on the vaginal and uterine epithelium.

The mechanism of action of steroid hormones: a new twist to an old tale

Steroid hormones, vitamins, and thyroid hormone are potent chemical messengers that exert dramatic effects on cell differentiation, homeostasis, and morphogenesis. These molecules, though diverse in structure, share a mechanistically similar mode of action. The effector molecules diffuse across cellular membranes and bind to specific high affinity receptors in the target cell nuclei. This interaction results in the conversion of an inactive receptor to one that can interact with the regulatory regions of target genes and modulate the rate of transcription of specific gene sets. The recent cloning and characterization of the functional receptors for these hormones has been enlightening as to the individual steps involved in steroid signal transduction. In addition, emerging evidence suggests that receptor function can be influenced by cell and promoter context indicating that it may be possible to develop tissue specific or tissue-restricted drugs. The concept that a single receptor can modulate gene transcription in a cell-specific manner is of great medical and pharmaceutical importance. The focus of this review is to highlight the recent developments in the steroid receptor field and to illustrate the novel approaches been undertaken to identify novel pharmaceuticals.

A clomiphene citrate and tamoxifen citrate combination therapy: a novel therapy for ovulation induction

OBJECTIVE

To assess the efficacy of a clomiphene citrate (CC) and tamoxifen citrate (CC/tamoxifen) combination therapy in ovulation induction by comparing with a CC alone therapy.

DESIGN

A randomized cross-over study with CC alone and CC/tamoxifen combination therapies for 20 normoprolactinemic anovulatory women. Randomly selected 10 of the 20 women (group A) underwent a CC alone therapy (100 mg CC during cycle days 5 to 9) for the initial three consecutive treatment cycles and a CC/tamoxifen combination therapy (50 mg CC and 20 mg tamoxifen during cycle days 5 to 9) for the subsequent three consecutive treatment cycles. The remaining 10 (group B) were treated similarly but with the inverse sequence. Ovulation was documented when a high BBT phase persisted for 11 days or more, when midluteal serum P levels exceeded 7 ng/mL (22.3 nmol/L), or when pregnancy ensued.

RESULTS

The rates of ovulatory/treated, pregnant/treated, and pregnant/ovulatory cycles were 42 of 56 (75.0%), 3 of 47 (6.4%), and 3 of 35 (8.6%) for CC/tamoxifen, respectively. Those were 25 of 57 (43.9%), 1 of 48 (2.1%), and 1 of 21 (4.8%) for CC, respectively. Clomiphene citrate/tamoxifen was more effective in ovulation induction than CC. All the pregnancies were normal and single. None of the treatments was accompanied by any remarkable side effects.

CONCLUSION

Clomiphene citrate/tamoxifen is a novel treatment modality of ovulation induction with high efficacy.

Preovulatory administration of clomiphene citrate to mice causes fetal growth retardation and neural tube defects (exencephaly) by an indirect maternal effect

Clomiphene citrate was administered to female mice at different doses and different times prior to ovulation, in the preimplantation period after ovulation, and after implantation. Pregnancy outcome was determined on day 15 of gestation, when the number of implantations and resorptions were calculated relative to the number of ovulations, and fetuses were assessed for size and stage of development and morphological abnormalities. Preovulatory administration of clomiphene citrate caused decreased implantation rates and growth retardation of surviving fetuses, the degree of the effect being dependent on the dose and the time of drug injection relative to ovulation. The implantation rate was lowest, and the degree of fetal growth retardation highest, when clomiphene citrate was administered immediately before ovulation. An increased incidence of exencephaly was found in the fetuses of females injected with clomiphene citrate prior to ovulation. Transfer of blastocysts from treated mice to untreated fosters showed the effect of clomiphene citrate on implantation and fetal growth to be predominantly mediated through the female reproductive tract, rather than a direct effect on the embryo itself. Administration of clomiphene citrate in the preimplantational period resulted in complete inhibition of implantation, while the only effect when administration was after implantation was a slight reduction in fetal weight. These results indicate that preovulatory clomiphene citrate impairs uterine function, which has an indirect effect on the growth and development of the postimplantation embryo.

Morphometric characteristics of endometrial biopsies after different types of ovarian stimulation for infertility treatment

OBJECTIVE

To investigate whether various types of ovarian stimulation induce differences in endometrial development at the midluteal phase in infertile women.

DESIGN

Assessment of stromal and glandular compartments in endometrial biopsies using morphometric criteria.

SETTING

Institute for Hormone and Fertility Research, Hamburg, Germany.

PATIENTS

The study included 18 women after treatment with human menopausal gonadotropin (hMG)/human chorionic gonadotropin (hCG) (group I), 23 women after clomiphene citrate (CC)/hMG/hCG treatment (group II), and 12 women after CC stimulation (group III).

INTERVENTIONS

Endometrial biopsies and blood samples were taken simultaneously in the early to midluteal phase. To assess the time of ovulation, hormone analysis and regular checks by ultrasonography were performed.

MAIN OUTCOME MEASURES

Morphometric evaluation of glandular and stromal structures revealed an impaired endometrial development after various treatment protocols.

CONCLUSION

Ovarian stimulation in infertile women results in most cases in an elevation of steroid levels; however, the occurrence of an inadequate endometrial development might have an unfavorable influence on the outcome of implantation. Therefore, these findings may be of importance to the choice of treatment for infertility.

Effects of antiestrogens on adult and neonatal mouse reproductive organs

Estrogenic potencies of various antiestrogens, including keoxifene (Kx) and trifluoperazine (Tfp), on reproductive tracts of ovariectomized adult mice, and effects of neonatal Kx and Tfp on reproductive organs were studied in C57BL/Tw mice. In adult ovariectomized mice, weight, DNA, and protein of the uterus and vagina were increased by 3 daily injections of 100 micrograms clomiphene, tamoxifen (Tx), and nafoxidine, and of 1 microgram estradiol-17 beta (E), but not by Kx. Antiestrogenic potency of Kx was studied in adult mice given injections of E. Kx significantly suppressed the E-induced increase in weight, DNA, and protein in the uterus and vagina. Tfp (20 micrograms), known as a tranquilizer and an antiestrogen, had no estrogenic effect on either organ. Male and female mice given 5 daily injections of Kx or Tfp from the day of birth were examined at 30, 40, and 60 days of age. Weights of testis, epididymis, and seminal vesicle in neonatally Kx-treated mice were significantly lower than in controls at 30 and 40 days. Spermatozoa were not formed in the seminiferous tubules of Kx-treated mice, although spermatogenesis occurred at 60 days. In neonatally Kx-treated females, weight of the uterus at 60 days and of the vagina at 40 and 60 days was significantly lower than in controls. Corpora lutea were absent from the ovaries of Kx-treated females. In neonatally Tfp-treated mice of both sexes at all ages examined, no differences were found in organ weights or histology, other than lower spermatogenic indices at 40 and 60 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of clomiphene citrate and its Zu or En isomers on the reproductive system of the immature male rat

The effect of clomiphene citrate (CC) and of its Zuclomiphene (ZuC) and Enclomiphene (EnC) isomers on the reproductive organs of immature male rats under different experimental conditions is reported. CC, ZuC, and EnC were administered daily to groups of either intact or castrated rats between the age of 21-44 d. This led to inhibition of weight increase of testis and accessory glands in the intact group. Spermatogenesis was arrested at the stage of primary spermatocyte following CC and ZuC treatment, and at the stage of young spermatids by EnC treatment. In the castrated group clomiphenes significantly stimulated weight increase of seminal vesicles (SV) compared with castrated control animals, but the former group were unable to achieve organ weight gain comparable to that in normal controls. Administration of human Chorionic Gonadotropin (hCG) together with CC or each of its isomers to intact animals, abolished the drug effect on spermatogenesis and on reproductive organ growth. Administration of CC, ZuC, and EnC together with testosterone to castrated animals, abolished the drug effect on growth inhibition of accessory glands. In intact treated rats LH and testosterone secretion were suppressed by all forms of clomiphenes. In the castrated group ZuC proved to be the most potent inhibitor of LH secretion. Therefore, it is inferred that ZuC and EnC have different potencies as far as their biological activity in the immature male rat is expressed.

Determination of estrogenic/antiestrogenic potential of antifertility substances using rat uterine peroxidase assay

The effect of three compounds (clomiphene citrate, centchroman, embelin) and plant-derived methanolic extracts (Abutilon indicum and Butea monosperma) was studied on uterotropic and uterine peroxidase activities in ovariectomized rats. It was observed that these two parameters were highly correlated in response to treatment with these test materials and also to estradiol. It was suggested that the uterine peroxidase assay could be utilized as a biochemical parameter in the screening of new antifertility agents for their estrogenic/antiestrogenic properties.

Effects of long-term treatment with estradiol or clomiphene citrate on bone maintenance, and pituitary and uterine weights in ovariectomized rats

Long-term estrogen replacement therapy in postmenopausal women can bring relief to hot flushes and reduce loss of bone mass due to osteoporosis, however, such treatment often can cause uterine hyperplasia and other undesirable effects. This study compared changes in bone mineral content (BMC), uterine weight, pituitary weight and pituitary gonadotropin content in the ovariectomized rat model following treatment with estradiol (E2) or two levels of clomiphene citrate (CC), an estrogen agonist/antagonist. Groups (n = 8-12) of adult ovariectomized (OVX) rat were implanted with E2 pellets (5 micrograms/day) or injected subcutaneously with CC at 1 mg/kg body wt (CC-1) or 5 mg/kg body wt (CC-5) twice weekly for 12 months. Placebo implanted OVX and intact (INT) female rats served as negative and positive controls, respectively. Following treatment, the uterus, pituitary gland and right femur were collected from each animal. E2 treatment increased (P less than 0.05) uterine weight compared to all other treatment groups, while both CC doses increased uterine weight over the OVX group only (E2, 0.24 +/- 0.03; INT, 0.14 +/- 0.01; CC-1, 0.06 +/- 0.01; CC-5, 0.07 +/- 0.01; and OVX, 0.02 +/- 0.01 g per 100 g body wt). Pituitary weight was increased 15-fold (P less than 0.05) by E2 treatment over all other treatment groups (E2, 65.7 +/- 13.9; INT, 4.0 +/- 0.5; CC-1, 3.3 +/- 0.03; CC-5, 2.7 +/- 0.02; and OVX, 2.9 +/- 0.02 mg per 100 g body wt). Both E2 and CC treatments reduced pituitary luteinizing hormone and follicle stimulating hormone content (micrograms/pit) to INT levels and were lower (P less than 0.05) than OVX levels. Mean BMC of E2, CC-1- or CC-5-treated rats was greater (P less than 0.05) than that of either the INT or OVX groups, while INT animals had a higher BMC compared to OVX animals (E2, 0.027 +/- 0.003; CC-1, 0.026 +/- 0.001; CC-5, 0.028 +/- 0.001; INT, 0.021 +/- 0.001; and OVX, 0.017 +/- 0.001 g/cm per 100 g body wt). These data indicate that CC has the potential to reduce bone mineral loss without causing other undesirable effects, including uterine hyperstimulation, and thus needs to be further investigated.