Embryo toxicity of clomiphene citrate on mouse embryos fertilized in vitro and in vivo

Effects of metformin and clomiphene citrate on ovarian vascularity in patients with polycystic ovary syndrome

OBJECTIVE

To evaluate the effects of metformin and of clomiphene citrate (CC) on the ovarian blood perfusion and on perifollicular and peri-corpus luteum (CL) vascularity in anovulatory women with polycystic ovary syndrome (PCOS).

DESIGN

Prospective cohort study.

SETTING

University "Magna Graecia" of Catanzaro.

PATIENT(S)

Forty anovulatory nonobese patients with PCOS who ovulated under treatment with metformin (850 mg twice daily) plus placebo (metformin group) and 38 under placebo plus CC (150 mg for 5 days; CC group). Another 30 healthy normal cycled women (control group).

INTERVENTION(S)

Serial transvaginal ultrasonographic examinations.

MAIN OUTCOME MEASURE(S)

Ovary artery blood flow impedance, dimensions, and vascularization of the dominant follicle and of the CL.

RESULT(S)

No difference was observed in all parameters in metformin ovulating cycles in comparison with healthy controls. In CC ovulating cycles, ovarian artery impedance, and perifollicular and peri-CL vascularization the results were significantly different from the metformin and control groups. After grouping the stimulated cycles for reproductive outcomes, perifollicular vascularization alone ended up being significantly lower only in CC-stimulated cycles with unfavorable outcome.

CONCLUSION(S)

In patients with PCOS who ovulate under treatment with metformin, the ovarian blood flows are similar to those observed in healthy women, whereas CC administration reduces the ovarian and, specifically, the perifollicular vascularization.

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.

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.

A comparison of clomiphene citrate and human menopausal gonadotropin for use in conjunction with intrauterine insemination

OBJECTIVE

To compare the outcome of superovulation using clomiphene citrate (CC) versus hMG in conjunction with IUI.

DESIGN

Sequentially assigned, observational study. Couples initially were assigned to receive either CC or hMG for three cycles.

SETTING

The Clinical Outpatient Department of the Dartmouth-Hitchcock Medical Center.

PATIENT(S)

Eighty-three infertile couples.

INTERVENTION(S)

IUI with hMG use.

MAIN OUTCOME MEASURE(S)

Conception rate, term pregnancy rate (PR), and pregnancy complications, such as spontaneous miscarriage and multiple gestation.

RESULT(S)

Of 83 couples who underwent at least one treatment cycle, 29 (35%) conceived during the study period. The relative rate of conception for hMG versus CC was 2.08 (95% confidence interval [CI], 0.93 to 4.68). The relative term PR was 2.10 (95% CI, 0.77 to 5.73) for hMG versus CC. There was no difference in the miscarriage rate for hMG versus CC.

CONCLUSION(S)

Both the conception rate and the term PR were higher using hMG, compared with CC, in combination with IUI, and showed a trend toward statistical significance.

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.

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.

The effect of clomiphene citrate on human preovulatory oocyte maturation in vivo

Sixty-four infertile women underwent diagnostic laparoscopy in the periovulatory period at time-bracketed intervals following their endogenous luteinizing hormone (LH) surge. Forty-eight of these women were studied during natural cycles and 16 had mild oligoovulation and were administered clomiphene citrate (CC) to regulate their cycles. No patient received human chorionic gonadotropin. No patient was undergoing either in vitro fertilization (IVF) or gamete intrafallopian transfer (GIFT). Follicle puncture was performed and the oocytes were observed immediately for stage of maturation. Oocytes obtained from follicles exposed to CC were found to require an increased interval of time to reach metaphase I compared to oocytes obtained from natural cycles (27.75 +/- 2.2 vs 22.5 hr; mean +/- SE). Furthermore, the interval of time required for metaphase I oocytes to achieve metaphase II was statistically significantly shortened for CC cycles (2.4 hr for CC vs 10 hr for natural cycles. Nevertheless, there was no difference between natural and CC cycles in the time interval between LH surge onset and ovulation. These in vivo findings suggest a direct effect of CC on human oocyte maturation and may help explain the well-established discrepancy between the relatively high ovulation rate and the relatively low conception rate in clomiphene-induced cycles.

Supplementation of Ham's F10 culture medium with three different sera in the culturing of baboon oocytes

1. Ten female baboons (Papio ursinus) were stimulated for a total of 20 cycles with 3 ovulation induction agents. 2. Oocytes obtained were randomly allocated to Ham's F10 culture medium supplemented with human fetal cord serum, primate serum or commercial fetal bovine serum respectively. 3. Fertilization occurred (38.1-45.5%) in all 3 supplements, but cleavage and embryo development was more successful in culture medium supplemented with fetal bovine serum. 4. Eight embryos were cultured and 6 (75%) of these were cultured in fetal bovine serum supplemented medium.

Effect of clomiphene citrate on in vitro ovulated ova

The effect of clomiphene citrate (CC) on developmental capacity of ovulated ova was studied with isolated in vitro perfused rabbit ovaries. Fifty-two ovulated ova were recovered from ovaries perfused with human chorionic gonadotropin (hCG) in a medium containing CC and 45 ova from ovaries perfused with hCG in a CC-free medium. Ova were cultured and inseminated with capacitated sperm and observed serially for evidence of fertilization and stage of development. CC did not affect the fertilization of ovulated ova. However, the percentage of ova which had reached the morula stage by 60 hours was significantly reduced in the CC-treated (15.4%) group, compared with the control group of ovaries (48.9%). A significant percentage of inseminated ova from CC-treated ovaries (65.4%) showed evidence of degeneration, as compared with control ovaries (37.8%). Thus, a partial loss of developmental capacity may explain the discrepancy observed between the rate of successful ovulation induction and the establishment of pregnancy associated with CC administration in humans.