Embryo implantation and GnRH antagonists: ovarian actions of GnRH antagonists

The association between treatment parameters on the day of gonadotropin-releasing hormone antagonist initiation during a flexible protocol and oocyte maturation rate

This study aimed to evaluate the effects of different treatment parameters on the day of GnRH antagonist initiation on oocyte maturation rate. We performed a retrospective cohort study of women aged ≤ 38 who underwent their first IVF-ICSI treatment using a flexible GnRH antagonist protocol in a single university-affiliated medical center during 2005-2015. Treatment parameters of three groups of oocyte maturation rates (<60%, 60-90%,>90%) were compared. Multivariate analysis was conducted to detect an association between treatment parameters on the day of GnRH antagonist initiation and oocyte maturation rate. The cohort included 458 patients, of whom 180 (39%) had a high oocyte maturation rate (≥90%), 211 (46%) had an oocyte maturation rate between 60-90% and 67 (15%) had a low maturation rate (≤60%). Women with a high maturation rate had longer duration of treatment (10.3 ± 2.9 days vs. 9.6 ± 2.5 vs. 9.5 ± 3.2, P = 0.019), lower levels of estradiol (1985 ± 1357 vs. 2406 ± 1666 vs. 2325 ± 1811, P = 0.027) and lower estradiol/maximal follicular diameter ratio on the day of GnRH antagonist initiation (137 ± 89 vs. 165 ± 103 vs. 163 ± 125, P = 0.019) as compared to women with medium and low maturation rates, respectively. Using linear regression multivariate analysis, lower estradiol and lower estradiol/maximal follicular diameter ratio on GnRH antagonist initiation day were associated with higher oocyte maturation rate. Further prospective studies to determine the best timing for GnRH antagonist initiation are needed.

The use of gonadotropin-releasing hormone antagonist post-ovulation trigger in ovarian hyperstimulation syndrome

The purpose of this paper is to assimilate all data pertaining to the use of gonadotropin-releasing hormone (GnRH) antagonists in in vitro fertilization cycles after ovulation trigger to reduce the symptoms of ovarian hyperstimulation syndrome (OHSS). A systematic review of the literature was performed to identify all studies performed on the use of a GnRH antagonist in IVF cycle post-ovulation trigger with patients at high risk for OHSS. Ten studies were identified and reviewed. Descriptions of the studies and their individual results are presented in the following manuscript. Due to significant heterogeneity among the studies, it was not possible to perform a group analysis. The use of GnRH antagonists post-ovulation trigger for treatment of OHSS has been considered for almost 20 years, though research into its use is sparse. Definitive conclusions and recommendations cannot be made at this time, though preliminary data from these trials demonstrate the potential for GnRH antagonists to play a role in the treatment of OHSS in certain patient populations.

Can steroidal ovarian suppression during the luteal phase after oocyte retrieval reduce the risk of severe OHSS?

Background

Ovarian stimulation in IVF cycle results in luteal supraphysiological steroid concentrations especially for high response patients. The aim of this study was to evaluate the efficacy of ovarian steroid hormone suppression in luteal phase after oocyte retrieval for preventing severe ovarian hyperstimulation syndrome (OHSS) in high-risk patients with embryo cryopreservation.

Methods

281 patients with high risk of OHSS were enrolled in this study among 4735 infertile women undergoing their first IVF treatment. The subjects were allocated into treatment and control group. The treatment group (n = 161) received letrozole (n = 43), mifepristone (n = 51), cetrotide (n = 39) and three-drug combinations (n = 28) during the luteal phase after oocyte retrieval, respectively. The control group (n = 120) received no medicine. Fertilization rate, good embryo rate, serum steroid concentration, clinical outcome, and incidence of severe OHSS were compared between the two groups.

Results

On days 2, 5 and 8 after oocyte retrieval, serum estradiol levels in the letrozole and three-drug combination therapy group were significantly lower than in the other three groups at the same time (P < 0.001, respectively). There were no significantly difference of serum luteinizing hormone concentration on days 2, 5 and 8 and progesterone concentration on day 8 after oocyte retreival among the five groups (P > 0.05, respectively). Compared with the control group, the incidence of severe OHSS, the paracentesis rate, the duration of hospitalization and the days of luteal phase in each subgroup of treatment groups was not significantly decreased (P > 0.05, respectively).

Conclusions

Our findings indicate that steroidal ovarian suppression in luteal phase after oocyte retrieval seems to be unable to prevent severe OHSS in high-risk patients with embryo cryopreservation.

Cetrotide administration in the early luteal phase in patients at high risk of ovarian hyperstimulation syndrome: A controlled clinical study

The aim of the present pilot study was to assess the feasibility and efficacy of Cetrotide administration in the early luteal phase in patients at high risk of ovarian hyperstimulation syndrome (OHSS), undergoing embryo cryopreservation following superovulation. A total of 135 patients at high risk of OHSS and undergoing embryo cryopreservation were divided into two groups. In the treatment group (n=39), the patients received daily subcutaneous injections of 0.25 mg Cetrotide between days 1 and 5 following ooctye retrieval, and volume expansion and symptomatic treatment were also provided. In the control group (n=96), the patients received routine treatments, including volume expansion therapy. The serum steroid hormone concentrations of the patients were measured on days 2, 5 and 8 following ooctye retrieval, while the incidence of moderate or severe OHSS, self-evaluated clinical symptoms and various clinical indicators were recorded. The serum estradiol (E₂), luteinizing hormone and progesterone levels in the treatment group on days 2, 5 and 8 following oocyte retrieval were not found to differ significantly when compared with the patients in the control group (P>0.05). The incidence of severe OHSS did not differ significantly between the two groups (P>0.05). The average length of hospital stay and length of luteal phase were not found to be significantly different between the treatment and control groups (P>0.05). In conclusion, Cetrotide injections in the early luteal phase did not alter the serum steroid levels of patients at high risk of OHSS undergoing embryo cryopreservation, and were unable to reduce the incidence of severe early OHSS. However, further randomized studies are required to evaluate the effectiveness of Cetrotide in the prevention of OHSS.

The role of GnRH antagonists in assisted reproduction

The different schemes of application of gonadotrophin-releasing hormone (GnRH) antagonists in ovarian stimulation protocols for assisted reproduction are reviewed. Starting from the initial schemes of single and/or multiple doses, the efficacy of GnRH antagonists in 'soft' protocols of ovarian stimulation has been evaluated in natural cycles, and the possibility of inducing the final oocyte maturation under antagonists either with native luteinizing hormone-releasing hormone or with GnRH agonists. The largest clinical studies carried out with cetrorelix or with ganirelix and published to date were analysed. Apart from the benefits of reducing the duration of the treatment, gonadotrophin requirements and ovarian hyperstimulation syndrome incidence, there is still a serious debate on the potential deleterious effect of GnRH antagonists on implantation and pregnancy rates. More specific aspects such as cycle programming, application of GnRH antagonists in protocols for poor responders etc., were also reviewed in this survey.

Treatment of ovarian hyperstimulation syndrome using gonadotropin releasing hormone antagonist: a pilot study

OBJECTIVE

This novel study describes an effective outpatient treatment for ovarian hyperstimulation syndrome (OHSS) that results in rapid normalization of symptoms.

STUDY DESIGN

A total of twenty-seven infertile women undergoing assisted reproductive technique with early-onset OHSS were enrolled in this non-randomized clinical trial in an academic infertility center. In all patients, after complete desensitization with long-term protocol ovarian stimulation with gonadotropins was commenced. Final oocyte maturation was triggered with human chorionic gonadotrophin. Oocytes were collected 36-38 h later using transvaginal-guided follicle aspiration under general anaesthesia. All embryos were frozen and study group patients received two consecutive doses of GnRH antagonist (Cetrotide) and the control group received daily dose of cabergoline for a week.

RESULTS

The research revealed that moderate and severe OHSS, hospitalization or acute care for OHSS and ascites tap were significantly lower in the antagonist (Cetrotide) group. The Patients' satisfaction with Cetrotide was noticeable. No side effect was reported in either group.

CONCLUSION

GnRH antagonists seem to be an effective outpatient treatment with rapid onset activity and minimal side effects for the management of early OHSS.

The effect of GnRH analogues for pituitary suppression on ovarian response in repeated ovarian stimulation cycles

INTRODUCTION

Ovarian stimulation is employed in assisted reproduction techniques in order to obtain as many oocytes as possible. The early rise in oestradiol levels may lead to the premature end of the respective cycle. In order to avoid such an effect, pituitary suppression has been employed. The aim of this study was to evaluate whether maintenance or replacement of the type of GnRH analogue (i.e., agonist or antagonist) employed for pituitary suppression in the consecutive intracytoplasmic sperm injection (ICSI) cycle would negatively influence oocyte quality and ICSI outcome.

MATERIAL AND METHODS

A retrospective observational study was conducted including 181 women with primary infertility. Patients were divided into four different groups according to the GnRH analogue used for pituitary suppression in the first and consecutive cycle.

RESULTS

When a GnRH agonist was employed for pituitary suppression in the first cycle, the consecutive cycle showed comparable outcomes when performed with either a GnRH agonist or a GnRH antagonist. When the first cycle was performed with a GnRH antagonist, the use of the GnRH agonist in the successive cycle led to an increased number of oocytes retrieved (7.5% vs. 10.3%, p = 0.032) and the production of a higher number of embryos (4.5% vs. 6.3%, p = 0.036).

CONCLUSIONS

When the first cycle is carried out with a GnRH antagonist, the use of a GnRH agonist in the successive cycle would lead to increased numbers of oocytes collected and embryos produced.

Follicular growth and oocyte maturation in GnRH agonist and antagonist protocols for in vitro fertilisation and embryo transfer

BACKGROUND

The aim of this study was to evaluate the response to treatment in a group of patients undergoing IVF and randomised to receive GnRH-antagonist or the GnRH-agonist. The endpoints were the pattern of follicular growth, the maturity of the oocytes collected, the embryo quality and the pregnancy outcome.

METHODS

A total of 136 patients undergoing IVF were included. Sixty-seven patients were allocated to the GnRH antagonist and 69 patients to the GnRH agonist. GnRH antagonist was administered when the leading follicle reached a diameter of 12-14 mm. GnRH agonist was administered in a long luteal protocol.

RESULTS

The mean numbers of oocytes retrieved and mature oocytes were significantly higher in the agonist than in the antagonist group (p < 0.02 and p < 0.01, respectively). Embryo quality, implantation rate, clinical pregnancy rates, ongoing pregnancy rate and miscarriage rate were similar in both groups.

CONCLUSIONS

Better follicular growth and oocyte maturation are achieved with GnRH agonist treatment. However, both regimens seem to have similar efficacy in terms of implantation and pregnancy rates. Further studies clarifying the effect of the GnRH antagonist on ovarian function are needed, as well as a clear definition of the best period of the follicular phase for the GnRH antagonist administration.

Follicular growth and development under continuous gonadotropin-releasing hormone antagonist administration

OBJECTIVE

Ovarian follicle and cyst formation have been recognized as an advance phenomenon associated with GnRH agonist administration. With the use of GnRH antagonists, pituitary suppression is immediate and no flare effect and follicle growth are expected. We describe two patients who developed a dominant follicle and presumably ovulated in response to hCG triggering under continuous sole administration of a GnRH antagonist.

DESIGN

Case report.

SETTING

An IVF unit at a university hospital.

PATIENT(S)

Two young healthy female patients undergoing IVF because of male-factor infertility.

INTERVENTION(S)

Continuous daily administration of a GnRH antagonist from menstruation with the aim of achieving ovarian suppression.

MAIN OUTCOME MEASURE(S)

Endocrine and ultrasound characteristics of follicular growth.

RESULT(S)

Both patients developed a dominant follicle under sole administration of a GnRH antagonist, accompanied by a gradual rise in serum estradiol and endometrial thickness which culminated in a spontaneous LH surge. Ovulation was triggered by hCG and mid-luteal progesterone levels were suggestive of ovulation.

CONCLUSION(S)

We describe for the first time the development of a dominant follicle and presumable ovulation under continuous administration of a GnRH antagonist. Serum gonadotropin concentrations indicate that the pituitary failed to suppress in both patients. The exact mechanism of this phenomenon remains to be elucidated.

Cryopreserved blastocyst transfer: impact of gonadotropin-releasing hormone agonist versus antagonist in the previous oocyte retrieval cycles

OBJECTIVE

To assess any detrimental effect of gonadotropin-releasing hormone (GnRH) antagonists on oocyte quality and embryo development by comparing the outcome of cryopreserved-thawed blastocyst transfers for cycles using a GnRH agonist or GnRH antagonist protocol for the controlled ovarian stimulation in the oocyte retrieval cycle.

DESIGN

Retrospective comparative study.

SETTING

Private IVF center.

PATIENT(S)

Seventy-seven women who underwent cryopreserved-thawed blastocyst transfer.

INTERVENTION(S)

The patients were divided into two groups based on whether they had been treated using a GnRH agonist long protocol (n = 44) or a GnRH antagonist multiple-dose protocol (n = 33) during the previous oocyte retrieval cycle. Cryopreserved-thawed blastocysts were transferred after endometrial preparation without pituitary suppression using a GnRH agonist.

MAIN OUTCOME MEASURE(S)

Implantation and clinical pregnancy rates.

RESULT(S)

The postthaw survival rate and numbers of good quality blastocysts transferred were similar for the GnRH agonist and GnRH antagonist groups. Implantation and pregnancy rates for cryopreserved-thawed blastocyst transfer for the GnRH agonist group versus the GnRH antagonist group were 21.0% (25 of 119) versus 29.0% (27 of 93) and 38.6% (17 of 44) versus 51.5% (17 of 33), respectively, which was not statistically significantly different.

CONCLUSION(S)

No difference was found in terms of implantation and pregnancy rates when a GnRH agonist or GnRH antagonist was used in the previous oocyte retrieval cycle. Our results suggest that GnRH antagonists do not have a detrimental effect on oocyte quality or embryo development.

Role of gonadotropin-releasing hormone antagonists in poor responders

OBJECTIVE

To evaluate the role of GnRH antagonists in poor-responder protocols.

DESIGN

Literature review.

CONCLUSION(S)

The optimum stimulation protocol for poor responders is unknown. Although many IVF programs currently use GnRH antagonists for poor responders, there have been only four prospective, randomized trials comparing GnRH antagonists to alternate protocols. None of these studies had sufficient power to evaluate a difference in pregnancy rates (PRs), and in all four cases, IVF outcomes were comparable. Nevertheless, interest in the use of GnRH antagonists in poor responders has continued. GnRH antagonists may be associated with simpler stimulation protocols, lower gonadotropin requirements, reduced patient costs, and shorter downtimes between consecutive cycles. However, the greatest advantage of GnRH antagonists may lie in the ability to assess ovarian reserves immediately prior to deciding whether or not to initiate gonadotropin stimulation. The ability to respond to cycle-to-cycle variation in antral follicle counts may allow the optimization of oocyte yield and reduce cycle cancellation rates. It remains to be seen if this approach (initiating gonadotropins only in cycles where an adequate antral follicle count is present) also translates into higher clinical PRs for poor responders.

Impact of estradiol patterns in clomiphene citrate/human menopausal gonadotropin/cetrorelix protocol

The importance of serum estradiol changes associated with gonadotropin-releasing hormone antagonists is not clear. The purpose of the present study was to analyze the impact of estradiol changes after cetrorelix injection on the outcome of intracytoplasmic sperm injection (ICSI) cycles. This was a prospective observational study. One hundred and thirteen women with male-factor infertility who were undergoing first ICSI cycles were reviewed for this study. Excluding seven cycles with incomplete data, 106 cycles were included in the analysis. The women were stimulated with clomiphene citrate and human menopausal gonadotropin (hMG). Cetrorelix acetate (2.5 mg) was given when the leading follicles reached 14 mm. After cetrorelix administration, serum estradiol rose in 48 cycles (45.3%), plateaued in 26 cycles (24.5%) and dropped in 32 cycles (30.2%). Mean age and day-3 follicle-stimulating hormone, luteinizing hormone and estradiol levels were similar among the three groups. The mean ampoules of hMG used, estradiol levels on the day of human chorionic gonadotropin injection and the clinical outcomes, including numbers of oocytes retrieved and fertilization, implantation and pregnancy rates, were similar in all three groups regardless of the trend of estradiol. In conclusion, estradiol patterns after cetrorelix injection show no correlation with clinical outcome and ovarian reserve, and falling estradiol is not associated with adverse outcome.

Cetrorelix in the treatment of female infertility and endometriosis

The use of cetrorelix within ovarian-stimulation protocols demonstrates several advantages compared with gonadotropin-releasing hormone (GnRH) agonist-containing protocols, which include, for example, significantly less time for analogue treatment and a reduction in the amount of gonadotropins needed. Furthermore, fewer side effects can be expected. There is no difference regarding endometrium quality and hormone profiles, and the results of assisted reproduction cycles are comparable. Cetrorelix also seems to be useful in the treatment of endometriosis which, in most cases, is an estrogen-dependent disease. Furthermore, fewer side effects occur with this agent (e.g., postmenopausal symptoms) and no estradiol add-back is needed. In the future, new nonpeptic GnRH antagonists are expected to be available for oral administration. Although they are still under investigation, these agents have the potential to improve patients' comfort and compliance.

Luteal phase characteristics following GnRH antagonist or agonist treatment - a comparative study

Due to inherent differences between gonadotrophin-releasing hormone (GnRH) antagonists and agonists, their late effect on ovarian steroidal production during the luteal phase of IVF cycles may differ. The aim of this study was to characterize and compare the luteal phase hormonal profile after the use of GnRH antagonists or agonists in ovarian stimulation protocols for IVF, in non-conception cycles, to avoid the effect of human chorionic gonadotrophin (HCG) during the luteal phase in conception cycles. Seventy-eight normo-ovulatory patients <35 years old, undergoing IVF due to male or tubal infertility were randomly allocated either to a GnRH antagonist (study group) or GnRH agonist treatment (control group). Similar standard luteal support was given to all patients, using vaginal micronized progesterone. In non-conception cycles, no statistically significant differences were found comparing luteal phase. oestradiol or progesterone levels in the study and control groups. No statistically significant differences were found comparing the hormonal profile dynamics, the mid-luteal (HCG day +8) oestradiol/progesterone ratio and the percentage of mid-luteal oestradiol decline between the study and control groups. In conclusion, similar characteristics and dynamics of luteal phase oestradiol and progesterone were demonstrated comparing ovarian stimulation for IVF using GnRH agonist or antagonists, under similar luteal support.

Long-term suppression of reproductive function by a single dose of gonadotropin-releasing hormone antagonists in a sheep model

OBJECTIVE

To determine the effect of single long-acting doses of GnRH antagonists on reproductive function in a sheep model.

DESIGN

Observational, model study.

SETTING

University-affiliated research unit.

ANIMAL(S)

Nine intact mature Merino sheep in experiment 1 and 12 mature Merino-crossed ewes with the ovary autotransplanted to the neck in experiment 2.

INTERVENTION(S)

Synchronization of estrous cycle either with intravaginal progestins or prostaglandin F2alpha analogues and treatment with a single dose of GnRH antagonist; evaluation of reproductive activity, plasma sampling, and ovarian ultrasonography.

MAIN OUTCOME MEASURE(S)

Determination of estrus behavior; plasma concentrations of P, FSH, LH, and inhibin A; and number and size of ovarian follicles.

RESULT(S)

In both experiments, the concentrations of FSH and LH were suppressed when compared with those in control ewes. In experiment 1, the ovulatory cycles were suppressed for > or = 55 days in treated sheep. In experiment 2, there were no follicles sized > or = 5 mm in treated ewes for 50 days.

CONCLUSION(S)

The suppression of the development of large follicles for > or = 30 days after a single injection of a long-acting GnRH antagonist provides a novel convenient method of pretreatment before COS.

Ovarian stimulation with GnRH agonist, but not GnRH antagonist, partially restores the expression of endometrial integrin 3 and leukaemia-inhibitory factor and improves uterine receptivity in mice

BACKGROUND

The impact of different ovarian stimulation (OS) protocols on endometrial receptivity remains controversial. In this study, the effects of different OS on the expression of endometrial integrin beta3 subunit and leukaemia-inhibitory factor (LIF) during the implantation window and the implantation rate in mice were investigated.

METHODS

Three OS protocols were used, involving either pregnant mare's serum gonadotrophin (PMSG) alone, PMSG plus GnRH agonist or PMSG plus GnRH antagonist. Uterus samples were collected at 48 h after OS or ovulation and were detected with immunohistochemistry, Western blot and RT-PCR analyses. Normal embryos at gestation day 4 were transferred into the uteri of mice in the control and OS groups.

RESULTS

All OS groups showed a significant decrease in the expression of both the endometrial integrin beta3 subunit and LIF during the implantation window and the implantation rate. Among the three OS groups, GnRH agonist-treated mice showed a higher endometrial integrin beta3 subunit and LIF expression and a higher implantation rate. No significant difference was found in the measured indices between the GnRH antagonist and PMSG groups.

CONCLUSIONS

OS may inhibit the expression of endometrial integrin beta3 subunit and LIF and impair endometrial receptivity in mice. OS with GnRH agonist, but not GnRH antagonist, may partially restore the endometrial physiological secretion and improve uterine receptivity.

Comparison of follicular fluid IGF-I, IGF-II, IGFBP-3, IGFBP-4 and PAPP-A concentrations and their ratios between GnRH agonist and GnRH antagonist protocols for controlled ovarian stimulation in IVF-embryo transfer patients

BACKGROUND

Insulin-like growth factors (IGF) and their binding proteins (IGFBP) play a major role in the autocrine and paracrine regulation of folliculogenesis. This is the first study that has compared follicular fluid (FF) IGF-I, IGF-II, IGFBP-3, IGFBP-4 and pregnancy-associated plasma protein (PAPP)-A concentrations, and their ratios, to investigate whether there was any difference in the intrafollicular microenvironment between the GnRH agonist (GnRHa) and antagonist (GnRHant) protocols for controlled ovarian stimulation (COS).

METHODS

A total of 68 IVF cycles were included in this study; two groups were studied: GnRHa long protocol group (n = 36) and the flexible GnRHant multiple-dose protocol group (n = 32). FF was obtained from dominant follicles during oocyte retrieval and stored at -70 degrees C until assayed. IGF-I, IGF-II and IGFBP-3 concentrations were measured by radioimmunoassay and IGFBP-4 and PAPP-A by enzyme-linked immunosorbent assay.

RESULTS

The duration of COS was significantly longer, and total dose of gonadotrophins used, serum estradiol (E(2)) levels on hCG day and the number of oocytes retrieved were significantly higher in the GnRHa long protocol group. The concentrations of FF IGF-II and IGFBP-4 were significantly higher, and the ratio of IGF-I/IGFBP-4 was significantly lower in the GnRHa long protocol group. Serum E(2) levels per mature follicle were not different between the two groups.

CONCLUSIONS

Our data may indicate a difference of intrafollicular microenvironment between cycles using GnRHa long protocols and those using GnRHant protocols. However, the difference in microenvironment does not appear to result in a difference in clinical outcome.

Effect of gonadotropin-releasing hormone agonist and antagonist on proliferation and apoptosis of human luteinized granulosa cells

The GnRH agonist leuprolide acetate (LA) inhibited DNA synthesis in epidermal growth factor-stimulated human granulosa luteinized cell cultures. This effect was blocked by the prior addition of a GnRH antagonist antide (ANT), and this compound per se was able to produce a stimulatory effect of DNA synthesis on basal conditions. Leuprolide acetate produced an increase in the percentage of apoptotic cells, and when these two factors were co-incubated, ANT blocked the apoptotic effect produced by LA.

Levels of apoptosis in human granulosa cells seem to be comparable after therapy with a gonadotropin-releasing hormone agonist or antagonist

OBJECTIVE

To compare levels of apoptosis in granulosa cells from women treated with the gonadotropin-releasing hormone (GnRH) agonist triptorelin or the GnRH antagonist cetrorelix.

DESIGN

Randomized, prospective study.

SETTING

University hospital.

PATIENT(S)

Thirty-two women undergoing assisted reproduction techniques after ovulation induction with recombinant follicle-stimulating hormone (FSH) plus GnRH agonist or antagonist.

INTERVENTION(S)

Granulosa cells were isolated from follicular aspirates after oocyte removal.

MAIN OUTCOME MEASURE(S)

Apoptosis was assessed with Annexin V binding assay, terminal deoxynucleotidyl transferase (TdT)-mediated nick-end labeling (TUNEL) assay, flow cytometric analysis of DNA, and ultrastructural analysis of cell morphology in transmission electron microscopy. Serum and follicular hormonal levels were also determined.

RESULT(S)

Annexin V binding and TUNEL assays revealed comparable percentages of apoptosis in the two groups under investigation. Analysis of DNA histograms revealed a similar cell cycle distribution in the two groups. Ultrastructural analysis only occasionally displayed patterns of chromatin margination in apoptotic cells. The mean concentrations of all the follicular fluid steroid hormones evaluated (E2, T, and P) were significantly lower in the GnRH antagonist-treated group.

CONCLUSION(S)

Therapy with a GnRH agonist or antagonist is associated with comparable levels of apoptosis in granulosa cells.

Comparison of embryo implantation in Wistar rats that underwent ovarian stimulation using exogenous gonadotropins associated with cetrorelix acetate or leuprolide acetate

OBJECTIVE

To compare embryo implantation in Wistar rats submitted to ovarian stimulation using recombinant FSH (rFSH) with cetrorelix acetate or leuprolide acetate.

DESIGN

Experimental study.

SETTING

Faculty of medicine animal facility.

PATIENT(S)

Fifty-six female Wistar rats with normal estrus cycles and 30 male.

INTERVENTION(S)

Ovarian stimulation and laparotomy (by the day 13 of gestation).

MAIN OUTCOME MEASURE(S)

Embryo implantation.

RESULT(S)

The female rats were subdivided into four groups: group 1, medicated with rFSH, hCG, and cetrorelix acetate; group 2, medicated with rFSH, hCG, and leuprolide acetate; group 3, medicated with rFSH and hCG; and group 4, in which only saline solution was administered. The female rats were mated with fertile male rats on the day of hCG administration with copulation confirmed through cytologic vaginal analysis. The females were killed on the 13th day of gestation. After laparotomy, comparison and identification was done regarding the numbers of corpora lutea and embryo implantations and gestation rates. Group 1 presented lower numbers of corpora lutea and embryo implantations in comparison to the other groups (P<.05). A difference was not found in the gestation rates between the groups.

CONCLUSION(S)

The number of embryo implantations in Wistar rats medicated with rFSH and cetrorelix acetate is lower than that of rats medicated with rFSH and leuprolide acetate.

Precycle administration of GnRH antagonist and microdose HCG decreases clinical pregnancy rates without affecting embryo quality and blastulation

The outcome of a novel protocol utilizing precycle gonadotrophin-releasing hormone (GnRH) antagonist administration and LH activity support with microdose recombinant human chorionic gonadotrophin (HCG) was compared to GnRH agonist long protocol used in patients undergoing their first ICSI (n=707) or IVF (n=571) cycles, which had resulted in one or two blastocyst transfers. In GnRH antagonist cycles, cetrorelix acetate (3 mg) was administered s.c. 4 days before FSH stimulation and a repeat dose was given when the lead follicular diameter was 13-14 mm. LH support was provided by recombinant HCG (2.5 microg). Embryo progression and blastulation were evaluated using embryo progression indices and blastocyst quality scores. The tested protocol demonstrated reduced implantation and clinical pregnancy rates as compared with GnRH agonist long protocol, although the embryo progression and blastulation parameters and blastocyst quality were comparable among the groups. Logistic regression models further supported the significant negative impact of GnRH antagonist/microdose HCG protocol on clinical pregnancy rates in both ICSI and IVF patients. Assisted reproduction cycles with fresh blastocyst transfers utilizing precycle GnRH antagonist administration and microdose HCG support resulted in lower implantation and clinical pregnancy rates as compared with GnRH agonist cycles, although the embryo progression and blastulation parameters were comparable.

The role of aromatase inhibitors in ameliorating deleterious effects of ovarian stimulation on outcome of infertility treatment

Clinical utilization of ovulation stimulation to facilitate the ability of a couple to conceive has not only provided a valuable therapeutic approach, but has also yielded extensive information on the physiology of ovarian follicular recruitment, endometrial receptivity and early embryo competency. One of the consequences of the use of fertility enhancing agents for ovarian stimulation has been the creation of a hyperestrogenic state, which may influence each of these parameters. Use of aromatase inhibitors reduces hyperestrogenism inevitably attained during ovarian stimulation. In addition, the adjunct use of aromatase inhibitors during ovarian stimulation reduces amount of gonadotropins required for optimum stimulation. The unique approach of reducing hyperestrogenism, as well as lowering amount of gonadotropins without affecting the number of mature ovarian follicles is an exciting strategy that could result in improvement in the treatment outcome by ameliorating the deleterious effects of the ovarian stimulation on follicular development, endometrial receptivity, as well as oocyte and embryo quality.

GnRH antagonists in IVF

The present review summarizes existing knowledge on the use of gonadotropin releasing hormone (GnRH) antagonists based on experience gathered after the completion of phase III comparative trials with GnRH agonists. Available data suggest that prolongation of the follicular phase significantly decreases the probability of pregnancy. Moreover, patients with elevated progesterone at initiation of stimulation have significantly fewer chances of achieving an ongoing pregnancy. Luteal support remains mandatory, while the replacement of human chorionic gonadotrophin by GnRH agonist does not appear to be feasible. Although not conclusive, existing data are not in favour of increasing the starting dose of gonadotrophins, of LH supplementation or of using a flexible antagonist protocol.

Clinical suppression of precocious puberty with cetrorelix after failed treatment with GnRH agonist in a girl with gonadotrophin-independent precocious puberty

This report presents the case of a 7-year-old girl with gonadotrophin-independent precocious puberty treated with cetrorelix [gonadotrophin-releasing hormone (GnRH) antagonist] after poor response to GnRH agonist therapy was observed in the endocrinology outpatient clinic. Uterine and ovarian morphology returned to within the normal prepubertal range after GnRH antagonist was injected subcutaneously. Vaginal bleeding stopped completely. The effects of GnRH antagonist treatment were comparable to those of GnRH agonist. The potential advantage of GnRH antagonists would be a clinically significant direct effect on the ovary, if it exists, and GnRH antagonists should be available for use in such children.

Extrapituitary effects of GnRH antagonists in assisted reproduction: a review

GnRH antagonists are used to prevent premature LH surges in assisted reproduction. The pregnancy rates obtained in several studies have been similar to those obtained in the long protocol with gonadotrophin-releasing hormone (GnRH) agonists. However, lower oestrogen serum concentrations have been observed and fewer oocytes retrieved using GnRH antagonists. Thus, potential effects at extrapituitary GnRH receptors in the ovary and the endometrium have been claimed. The article reviews the currently available data from the literature as well as current investigations with respect to effects of cetrorelix on the ovary and the endometrium. No evidence was found to support the hypothesis of extrapituitary effects of GnRH antagonists such as cetrorelix at doses used in assisted reproduction.

Exaggerated 17-hydroxyprogesterone response to intravenous infusions of recombinant human LH in women with polycystic ovary syndrome

Studies using pharmacological gonadotropin stimulation suggest that ovarian steroidogenesis is abnormal in the polycystic ovary syndrome (PCOS). We assessed ovarian steroid secretion in response to near-physiological gonadotropin stimuli in 12 ovulatory controls and 7 women with PCOS. A gonadotropin-releasing hormone-receptor antagonist (ganirelix, 2 mg sc) was given to block endogenous LH secretion, followed by dexamethasone (0.75 mg orally) to suppress adrenal androgen secretion. After ganirelix injection (12 h), intravenous infusions of recombinant human LH (0, 10, 30, 100, and 300 IU; each over 8 min) were administered at 4-h intervals in a pseudorandomized (highest dose last) manner. Plasma LH, 17-hydroxyprogesterone (17-OHP), androstenedione, and testosterone were measured concurrently. LH dose-steroid response relationships (mean sex-steroid concentration vs. mean LH concentration over 4 h postinfusion) were examined for each subject. Linear regression of 17-OHP on LH yielded a higher (mean +/- SE) slope in PCOS (0.028 +/- 0.010 vs. 0.005 +/- 0.005, P < 0.05), whereas extrapolated 17-OHP at zero LH was similar. The slopes of other regressions did not differ from zero in either PCOS or controls. We conclude that near-physiological LH stimulation drives heightened 17-OHP secretion in patients with PCOS, suggesting abnormalities of early steps of ovarian steroidogenesis. With the exception of 17-OHP response in PCOS, no acute LH dose-ovarian steroid responses were observed in controls or PCOS. Defining the precise mechanistic basis of heightened precursor responsiveness to LH in PCOS will require further clinical investigation.

Duration of gonadotropin-releasing hormone antagonist administration does not affect the outcome of subsequent frozen-thawed cycles

The duration of administration of GnRH antagonist in cycles stimulated with recombinant FSH for IVF/intracytoplasmic sperm injection does not affect the probability of blastocyst replacement and of achieving an ongoing pregnancy in subsequent frozen-thawed cycles.

Gonadotropin-releasing hormone and reproductive medicine

The hypothalamic gonadotropin-releasing hormone (GnRH) is a key regulator of the reproductive system, mainly through its effects on pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. Gonadotropin-releasing hormone analogues are modifications of the natural decapeptide, being either agonists (GnRHa) or antagonists. GnRHa may imitate the native hormone and induce an endogenous LH surge; however, sustained treatment with GnRHa results in complete refractoriness of LH and FSH production. This aspect of GnRHa action is the main application of the GnRHa in reproduction today. The hypogonadotropic hypogonadal state that results from the sustained treatment is the basis for additional applications of the GnRHa. The agonists appear to be effective, to some extent, for the treatment of endometriosis and were proved to be beneficial prior to surgery for fibroma uteri. GnRHa is used in assisted reproduction for both induction of an endogenous LH surge and for induction of ovulation, and its capacity to cause refractoriness of the pituitary may be used to avoid a premature LH surge. It is suggested that the GnRHa have a direct effect on ovarian steroidogenesis, which is independent of its action on the pituitary. This unwanted effect and other possible drawbacks of the agonists are thought to be eliminated with the use of the antagonists. The mechanism of action of these antagonists is through competitive blocking of the GnRH receptor, which results in a rapid but reversible suppression of gonadotropin secretion. As for GnRHa, GnRH antagonists have been proven effective to prevent the LH surge and to reduce the incidence of severe ovarian hyperstimulation syndrome in controlled ovarian stimulation cycles.

Gonadotropin-releasing-hormone-receptor antagonists

Pulsatile gonadotropin-releasing hormone (GnRH) stimulates the pituitary secretion of both luteinising hormone (LH) and follicle-stimulating hormone (FSH) and thus controls the hormonal and reproductive function of the gonads. Blockade of GnRH effects may be wanted for a variety of reasons-eg, to prevent untimely luteinisation during assisted reproduction or in the treatment of sex-hormone-dependent disorders. Selective blockade of LH/FSH secretion and subsequent chemical castration have previously been achieved by desensitising the pituitary to continuously administered GnRH or by giving long-acting GnRH agonists. Only recently have GnRH-receptor antagonists, that immediately block GnRH's effects, been developed for clinical use with acceptable pharmacokinetic, safety, and commercial profiles. In assisted reproduction, these compounds seem to be as effective as established therapy but with shorter treatment times, less use of gonadotropic hormones, improved patient acceptance, and fewer follicles and oocytes. All current indications for GnRH-agonist desensitisation may prove to be indications for a GnRH antagonist, including endometriosis, leiomyoma, and breast cancer in women, benign prostatic hypertrophy and prostatic carcinoma in men, and central precocious puberty in children. However, the best clinical evidence so far has been in assisted reproduction and prostate cancer.

Gonadotrophin-releasing hormone antagonists for assisted conception

BACKGROUND

Over the last two decades, a long protocol of Gonadotrophin-releasing hormone agonist (GnRHa) to prevent premature LH surges has been the standard treatment for ovarian stimulation in assisted reproduction. In the long protocols (with GnRHa started either in the mid luteal phase or in the early follicular phase of the preceding cycle) gonadotrophin administration is delayed until pituitary desensitization has been achieved, which usually takes 2-3 weeks. Gonadotrophin-releasing hormone antagonists produce immediate suppression of gonadotrophin secretion, hence, they can be given after starting gonadotrophin administration. This will result in dramatic reduction in the duration of treatment cycle and will avoid estrogen deprivation symptoms associated with GnRH agonist induced down-regulation. Assuming comparable clinical outcome, these benefits would justify a change from the standard long protocol of GnRH agonists to the new GnRH antagonist regimens.

OBJECTIVES

To compare the efficacy of gonadotrophin-releasing hormone (GnRH) antagonists with the standard long protocol of GnRH agonists for controlled ovarian hyperstimulation in assisted conception.

SEARCH STRATEGY

Search strategies included on-line searching of the MEDLINE and EMBASE databases and the Cochrane Menstrual Disorders and Subfertility Group's Specialised Register from 1982 to 2001, and hand searching of bibliographies of relevant publications and reviews, and abstracts of scientific meetings.

SELECTION CRITERIA

Only randomised controlled studies comparing different protocols of GnRH antagonists with GnRH agonists in assisted conception cycles were included in this review.

DATA COLLECTION AND ANALYSIS

Data were extracted into 2 x 2 tables. For the primary outcomes, clinical pregnancy per woman randomised and prevention of premature LH surge, the overall common odds ratio (OR) and the risk difference with 95% confidence interval (CI) were calculated after verifying the presence of homogeneity of treatment effect across all trials. Secondary outcomes considered were the number of oocytes retrieved, clinical pregnancy per oocyte retrieval and per embryo transfer, spontaneous abortion, incidence of severe ovarian hyperstimulation syndrome and the amount of gonadotrophins used. Where relevant data were missing or unclear the authors were consulted.

MAIN RESULTS

Five trials comparing the new fixed protocol of GnRH antagonist to the long protocol of GnRH agonist fulfilled the inclusion criteria and were included. In four studies, the multiple low-dose (0.25 mg) antagonist regimen was applied and in one study, the single high-dose (3 mg) antagonist regimen was investigated. In all trials, reference treatment included a long protocol of GnRHa (buserelin, leuprorelin or triptorelin) starting in the mid-luteal phase of the preceding cycle. In comparison to the long protocol of GnRHa, the overall OR for the prevention of premature LH surges was 1.76 (95% CI 0.75, 4.16), which is not statistically significant. There was a significantly fewer clinical pregnancies in those treated with GnRH antagonists (OR 0.78, 95% CI 0.62, 0.97). The absolute treatment effect (ATE) was calculated to be 5%. The number needed to treat (NNT) was 20. There was a statistically significant reduction in incidence of severe ovarian hyperstimulation syndrome, (RR 0.36, 95% CI 0.16, 0.80) using antagonist regimens as compared to the long GnRHa protocol.

REVIEWER'S CONCLUSIONS

The new fixed GnRH antagonist protocol (i.e. with antagonist start fixed on day 6 of gonadotrophin stimulation) is a short and simple protocol with a significant reduction in incidence of severe OHSS but a lower pregnancy rate compared to the GnRH agonist long protocol. There is a non significant difference between both protocols regarding prevention of premature LH surge. The clinical outcome may be further improved by developing more flexible antagonist regimens taking into account individual patient characteristics. The GnRH antagonist flexible regimen should be the area of research in the near future.