An overview of GnRH antagonists in infertility treatments. Introduction

Effects of macrophage depletion on characteristics of cervix remodeling and pregnancy in CD11b-dtr mice

To test the hypothesis that macrophages are essential for remodeling the cervix in preparation for birth, pregnant homozygous CD11b-dtr mice were injected with diphtheria toxin (DT) on days 14 and 16 postbreeding. On day 15 postbreeding, macrophages (F4/80+) were depleted in cervix and kidney, but not in liver, ovary, or other non-reproductive tissues in DT-compared to saline-treated dtr mice or wild-type controls given DT or saline. Within 24 h of DT-treatment, the density of cell nuclei and macrophages declined in cervix stroma in dtr mice versus controls, but birefringence of collagen, as an indication of extracellular cross-linked structure, remained unchanged. Only in the cervix of DT-treated dtr mice was an apoptotic morphology evident in macrophages. DT-treatment did not alter the sparse presence or morphology of neutrophils. By day 18 postbreeding, macrophages repopulated the cervix in DT-treated dtr mice so that the numbers were comparable to that in controls. However, at term, evidence of fetal mortality without cervix ripening occurred in most dtr mice given DT-a possible consequence of treatment effects on placental function. These findings suggest that CD11b+ F4/80+ macrophages are important to sustain pregnancy and are required for processes that remodel the cervix in preparation for parturition.

Leuprolide acetate reduces both in vivo and in vitro ovarian steroidogenesis in infertile women undergoing assisted reproduction

Despite the probable inhibitory effects of GnRH analogues on ovarian steroidogenesis in vitro, their association with assisted reproduction protocols shows favorable results. This suggests that there are important differences in the behaviors of these drugs when administered in vivo versus in vitro. To clarify these differences, this study was designed to analyze the effect of leuprolide acetate (LA) on ovarian steroidogenesis in women undergoing In Vitro Fertilization (IVF). A prospective, randomized open label study was conducted on 14 women (26-35 years): seven receiving only gonadotrophins (Group 1) and seven receiving gonadotrophin plus LA at 1mg/day (Group 2). The LA in vivo effect was determined with serum and follicular fluid (FF) samples and via luteinized granulosa cell cultivation (GCC), where cells were obtained during oocyte retrieval after ovarian hyperstimulation. In vitro analysis was performed via addition of LA to GCC only for Group 1 (without LA) at progressively higher concentrations (0, 10(-12), 10(-9) and 10(-6)M). In vivo, the main observation was a reduction in androgen production in Group 2, represented by lower androstenedione production in FF (G1=6479+/-3458; G2=3021+/-1119 ng/ml; p=0.04) and a lower testosterone peak in GC at 96h (G1=0.64+/-0.12 ng/ml; G2=0.50+/-0.19 ng/ml; P=0.02), but a higher fertilization rate (G1=67%; G2=83%; p=0.009). In vitro, testosterone, estradiol and progesterone were also reduced by LA, even though this reduction occurred for progesterone only at the highest LA dosage (10(-6)M; 606.0+/-114.3 ng/ml versus 1524.0+/-246.5 ng/ml; p=0.02). Results show that LA reduces ovarian steroidogenesis in vivo by essentially inhibiting androgen synthesis; whereas, in vitro, ovarian steroidogenesis is reduced overall.

The effects of GnRH antagonist on the endometrium of normally menstruating women

PURPOSE

To study the effects of GnRH antagonist (ganirelix-Orgalutran) on the endometrium of regularly menstruating women.

MATERIALS AND METHODS

Prospective, self-controlled study. The thirty-five volunteers were studied for two cycles: one as a control and the other, GnRH antagonist-treated cycles in which ganirelix 0.25 mg/d was given daily for 3 days, starting when the largest follicle reached 15 mm. In both cycles, serum estradiol, LH and endometrial thickness were measured when the largest follicle was > or =18 mm. Endometrial biopsy was performed on day 6 after ovulation for histological dating and morphometric study.

RESULTS

No statistical differences between histological dating and the endometrial thickness in the control and GnRH antagonist-treated cycles. All morphometric parameters were also not different. Serum estradiol and LH levels were significantly lower in GnRH antagonist-treated cycles.

CONCLUSION

GnRH antagonist has no effect on the endometrium of regularly menstruating women as assessed by either histological dating or morphometric analysis.

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.

Emerging drugs in assisted reproduction

Infertility affects approximately 15% of couples of reproductive age. In assisted reproductive technology (ART), medications play a crucial role in stimulating ovaries to produce several oocytes and prepare the endometrium to be receptive after replacing one or more embryos into the uterine cavity. The availability of recombinant human follicle stimulating hormone, luteinising hormone and human chorionic gonadotrophin; of gonadotrophin-releasing hormone (GnRH) agonists and antagonists; and of luteal supplementation with progesterone have allowed the tailoring of several stimulation schemes, which have enhanced the pregnancy outcome after ART treatment. However, the remaining risk of ovarian hyperstimulation syndrome, the still low implantation rates, the unacceptably high rates of multiple pregnancies and the daily parenteral administration of medications do not constitute the features of a patient-friendly procedure. Therefore, a number of molecules with gonadotrophin-like activity, inhibition of GnRH receptor ability, or endometrium receptivity enhancement properties are currently under active investigation. Orally bioactive therapeutic preparations, in particular, may revolutionize in vitro fertilisation (IVF) treatment in the near future. Nevertheless, the implementation of mild ovarian stimulation protocols with single embryo transfer policy and further development of oocyte in vitro maturation techniques may lead to a less drug orientated IVF treatment.

Ganirelix acetate use in normal- and poor-prognosis patients and the impact of estradiol patterns

OBJECTIVE

To evaluate cycle outcomes in patients with either poor or normal prognosis undergoing IVF treatment with a GnRH antagonist (ganirelix acetate) for LH suppression.

DESIGN

Nonrandomized, noncontrolled, retrospective review.

PATIENT(S)

204 patients, aged 23-41 years, undergoing IVF.

INTERVENTION(S)

Patients completed 225 consecutive cycles of IVF with a GnRH antagonist (Antagon; Organon, Roseland, NJ) for LH surge prevention. Sixty cycles were conducted in patients with a known poor prognosis, whereas 165 were conducted in patients with a normal IVF prognosis.

MAIN OUTCOME MEASURE(S)

Pregnancy rate (PR), for the series as a whole and according to prognosis, and serum E2 patterns.

RESULT(S)

The PR per initiated cycle for the series as a whole was 33.3%. The pregnancy rate was 42.1% per ET for the entire series, with a cycle cancellation rate of 21%. When evaluated by prognosis, the poor-prognosis patients had PRs of 8.3% per attempt and 15% per transfer, whereas the normal-prognosis patients had PRs of 40% per attempt and 45% per transfer. Pregnancy rate did not vary by E2 pattern (drop, plateau, or rise). Oral contraceptive pretreatment was noted to be associated with high cancellation rates in the group of known poor responders, whereas for the group as a whole, cycle outcome was unaffected by the use of oral contraceptives.

CONCLUSION(S)

Use of GnRH antagonists in patients with an a priori poor IVF prognosis results in predictably poor outcomes. Patients without factors predicting poor outcome have acceptable PRs. The pattern of E2 rise immediately after initiation of GnRH antagonists does not predict cycle outcome. Oral contraceptives can be successfully used to schedule antagonist-based IVF cycles but might increase the risk of cycle cancellation in some patient populations.