Effects of a gonadotropin releasing hormone agonist on oocyte maturation, fertilization, and embryonal development of mice

Effects of luteal estradiol pre-treatment on the outcome of IVF in poor ovarian responders

BACKGROUND

In view of the discrepancies about the luteal estradiol treatment before stimulation protocols having some potential advantages compared with the standard protocols in poor ovarian responders undergoing IVF, a meta-analysis of the published data was performed to compare the efficacy of the luteal estradiol pre-treatment protocols in IVF poor response patients.

METHODS

We searched for all published articles. The searches yielded 32 articles, from which seven studies met the inclusion criteria. We performed this meta-analysis involving 450 IVF patients in luteal estradiol pre-treatment protocol group and 606 patients in standard protocol group.

RESULTS

The luteal estradiol protocol resulted in a significantly higher duration of stimulation compared with the standard protocol. In addition, the number of oocytes retrieved and mature oocytes retrieved were significantly higher in the luteal estradiol protocols than those in the standard protocols. The cycle cancellation rate (CCR) in the luteal estradiol protocols was lower than the standard protocols. Moreover, no significant difference was found in the clinical pregnancy rate (CPR).

CONCLUSIONS

The addition of the estradiol in the luteal phase preceding IVF in poor responders improved IVF cycle outcomes, including increasing the number of oocytes retrieved and mature oocytes retrieved and decreasing the CCR.

In vitro fertility rate of 129 strain is improved by buserelin (gonadotropin-releasing hormone) administration prior to superovulation

The 129 mice are well recognized for their low fertility and it is speculated that this lack of fertility may be due to the oocyte condition. In this study we investigated superovulation regimens for the 129S1/SvImJ mouse strain to improve the oocyte quality and fertility rate of in vitro fertilization (IVF). Female mice were divided into four groups based on hormone and timing of injection. Group 1 received pregnant mare serum gonadotropin (PMSG) and 48 h later human chorionic gonadotropin (hCG); using the same dose, group 2 received hCG 52 h post-PMSG and group 3, 55 h post-PMSG. Group 4 received buserelin (gonadotropin-releasing hormone agonist [GnRH]) followed 24 h later by PMSG and then hCG 55 h post-PMSG. IVF was performed using 129S1/SvImJ oocytes and sperm; C57BL/6J sperm with 129S1/SvImJ oocytes was used as fertility control. The IVF fertility rate was 1% (Groups 1 and 2), 17% (Group 3) and 55% (Group 4) for 129 oocytes fertilized with 129 sperm. For 129 oocytes fertilized with C57BL/6J sperm, the fertility rate was 5% (Group 1), 10% (Group 2), 40% (Group 3) and 59% (Group 4). These results suggest that extending the interval time between PMSG and hCG and giving GnRH in addition to the standard PMSG and hCG treatments can improve IVF fertility rate of 129S1/SvImJ mouse strains significantly.

Effect of estrogen priming through luteal phase and stimulation phase in poor responders in in-vitro fertilization

PURPOSE

To verify whether a novel protocol administering E(2) during the luteal phase of the preceding cycle and during ovarian stimulation in GnRH antagonist cycle could enhance follicular response and hence improve outcomes in poor responders.

METHODS

In this retrospective analysis, a total of 155 poor responder patients subjected to IVF/ICSI were analyzed. All the patients had history of more than one prior IVF cycle failure with poor response (less than 5 oocytes retrieved and/or maximal E₂ level less than 500 pg/mL) by using conventional long agonist or antagonist protocol. In luteal E2 treatment protocol (n = 86), oral estradiol valerate 4 mg/day was initiated on luteal day 21 and either stopped at menstrual cycle day 3 (Protocol A, n = 28) or continued during the period of ovarian stimulation until the day of hCG injection (Protocol B, n = 58). IVF parameters and pregnancy outcome of luteal E2 treatments group were compared with a standard GnRH antagonist protocol (n = 69) which the patients received no hormonal pretreatment.

RESULTS

Compared to standard GnRH antagonist protocol, cancellation rate was lower with luteal E2 group (15.1% vs 37.7%, p < 0.01). Moreover, patients treated with luteal estrogen resulted in an increased number of oocytes retrieved (4.5 ± 2.9 vs 3.2 ± 1.9; p < 0.01). A trend toward increase in number of normally fertilized embryos (2.9 ± 2.1vs 2.3 ± 1.9; p = 0.043), and increased prevalence of good quality embryos (51.2% vs 25%; p = 0.047) were noted. Comparing protocol A and B, there were no significant difference between embryologic data, however there were slight increase in ongoing pregnancy rate in protocol B compared to A (27.1% vs 20%, p = 0.357), although statistical significance was not achieved.

CONCLUSION

Estrogen priming through luteal phase and stimulation phase improved ovarian responsiveness and this may lead to an increase in pregnancy rate in poor responders with failed cycle.

Endocrine, morphological, and cytological effects of a depot GnRH agonist in bovine

The present study was conducted to assess effects of the gonadotropin-releasing hormone agonist (GnRHa) triptorelin in dairy heifers. The peptide was released from a commercial 4-week depot formulation (Decapeptyl Depot) administered at animals' estrus (day 0). First experiment (EXP I, n=5), which was aimed to explore the availability of peptide, detected a maximum of triptorelin concentration between day 2 and 5 after depot injection, and the peptide remained detectable by RIA in peripheral blood for about 3 weeks. In further experiments, the peptide release was terminated on day 9 (EXP II, n=16) or day 21 (EXP III, n=47). Treatment effects were studied on follicular development, the characteristics of cumulus-oocyte complexes (COCs) (EXP II; EXP IIIa) and secretions of LH and progesterone (EXP IIIb). Results showed that the occurrence of the pre-ovulatory LH surge was more uniform in treated heifers than that in controls. The duration of ovulation periods was similar amongst the heifers of EXP II, but more compact amongst those of EXP III each compared with the respective controls. Post-ovulatory, the number of LH pulses was significantly reduced by treatment, whereas both basal LH and progesterone concentrations were elevated on a few days. Follicular growth was reduced only by the prolonged influence of the GnRHa. There were increased proportions of both degenerated COCs and immature oocytes from small follicles (<3mm in diameter), and meiotic configuration and quality of oocytes isolated from follicles 3-5mm were changed after the prolonged, 21-day treatment. These results indicate that a continuous influence of a GnRHa over more than 1 week may increasingly impair the development of bovine follicles and oocytes. This may have some significance for the development of novel GnRH-based techniques in regulating the reproductive function in cattle.

Gonadotropin-releasing hormone induces actin cytoskeleton remodeling and affects cell migration in a cell-type-specific manner in TSU-Pr1 and DU145 cells

GnRH was first identified as the hypothalamic decapeptide that promotes gonadotropin release from pituitary gonadotropes. Thereafter, direct stimulatory and inhibitory effects of GnRH on cell proliferation were demonstrated in a number of types of primary cultured cells and established cell lines. Recently, the effects of GnRH on cell attachment, cytoskeleton remodeling, and cell migration have also been reported. Thus, the effects of GnRH on various cell activities are of great interest among researchers who study the actions of GnRH. In this study, we demonstrated that GnRH induces actin cytoskeleton remodeling and affects cell migration using two human prostatic carcinoma cell lines, TSU-Pr1 and DU145. In TSU-Pr1, GnRH-I and -II induced the filopodia formation of the cells and promoted cell migration, whereas in DU145, GnRH-I and -II induced the formation of the cells with stress fiber and inhibited cell migration. In our previous studies, we reported the stimulatory and inhibitory effects of GnRH on the cell proliferation of TSU-Pr1 and DU145 cells. This study provides the first evidence for the effects of GnRH on actin cytoskeleton remodeling and cell migration of cells in which cell proliferation was affected by GnRH at the same time. Moreover, we also demonstrated that the same human GnRH receptor subtype, human type I GnRH receptor, is essential for the effects of GnRH-I and -II on actin cytoskeleton remodeling and cell migration in both TSU-Pr1 and DU145 cells using the technique of gene knock-down by RNA interference.

The role of gonadotropin-releasing hormone (GnRH) and its receptor in development of porcine preimplantation embryos derived from in vitro fertilization

This study was performed to investigate the expression of embryo-derived gonadotropin-releasing hormone (GnRH) and its receptor, and to determine the role of GnRH in porcine preimplantation embryos. In Experiment 1, porcine blastocysts derived from in vitro fertilization (IVF) and cultured in North Carolina State University (NCSU)-23 medium were subjected to reverse transcription polymerase chain reaction (RT-PCR) amplification with specific primers for GnRH and its receptor. The results showed that GnRH and its receptor were expressed in porcine IVF blastocysts. In order to investigate the role of GnRH in embryo development, porcine IVF embryos were cultured in NCSU-23 supplemented with different concentrations (0, 0.1, 1, or 10 microM) of a GnRH agonist (leuprolide, Experiment 2) or GnRH antagonist (antide, Experiment 3). Supplementing the culture medium with 0.1 or 1 microM leuprolide increased the rate of blastocyst formation (28.5 or 27.6% versus 20.2%) and mean total cell number (129 versus 104) compared to the control group. In contrast, antide significantly decreased the rate of blastocyst formation [12.6% (0.1 microM), 10.2% (1.0 microM), or 8.9% (10.0 microM) versus 22.8% (control)] and total cell number [69 (1 microM) or 68 (10 microM) versus 104 (control)]. In Experiment 4, porcine IVF embryos were cultured in NCSU-23 medium containing 1 microM antide plus 1 microM leuprolide. The embryotrophic effect of GnRH agonist was reversed by co-supplementing with GnRH antagonist. In conclusion, the present study demonstrated that supplementing a culture medium with GnRH agonist can improve blastocyst formation and the quality of porcine IVF embryos, and that this action was mediated through GnRH receptors.

Effects of a GnRH agonist on oocyte number and maturation in mice superovulated with eCG and hCG

The objective was to investigate the effects of a gonadotropin-releasing hormone agonist (GnRH) on ovulation rate and the number and maturation of oocytes in mice superovulated with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG). Thirty 3-month-old BALB/C female mice (weight: 25-30 g) were assigned to three experimental groups: control, superovulated, and superovulated with GnRH pretreatment (n=10 per group). Control mice received an i.p. injection of 0.1 ml physiological saline solution. Superovulation was induced with 5 IU eCG (i.p.) and 5 IU hCG 48 h later. Mice in the superovulated with GnRH pretreatment group were given GnRH (20 mg/kg Fertirelin, i.m.), 24 h before superovulation. Thirteen hours after hCG administration, mice were sacrificed by cervical dislocation and blood samples were collected to determine serum progesterone concentration (by radioimmunoassay). Ovaries and oviducts were also harvested to enumerate corpora lutea and cumulus-enclosed oocytes. Progesterone concentrations were not significantly different among groups. The oocyte number and the maturation, ovulation rate, and the number of corpora lutea were higher in GnRH-treated mice than both controls and superovulated mice. In conclusion, GnRH given 24 h before superovulation with eCG-hCG increased the number and maturation of oocytes and the rate of ovulation in mice.

Improvement of IVF outcome in poor responders by discontinuation of GnRH analogue during the gonadotropin stimulation phase--a function of improved embryo quality

PURPOSE

To assess the efficacy of a protocol involving the discontinuation of the GnRH analogue at the mid-phase of ovarian stimulation for IVF in patients with a previous poor response.

METHODS

Prospective case-control evaluation compared with same patient's previous performance. Thirty-six patients enrolled in an IVF program were treated in two consecutive cycles. The first with a standardized protocol utilizing midluteal administration of Nafarelin (N) 600 mcg/d continued throughout the stimulation phase with human menopausal gonadotropin (hMG) until follicles of 20 mm were identified by transvaginal ultrasound (Standard group). Patients with a poor response in the Standard cycle were treated in the subsequent cycle with N and hMG initially in a similar manner, then N was stopped after 5 days of hMG stimulation (N-stop group). All clinical and laboratory aspects of treatment were done in a similar fashion in both cycles, each patient acting as her own control.

RESULTS

Results were analyzed by paired t test. The change in each parameter in the N-stop cycle was expressed as the percent change as compared with the standard protocol cycle for each patient. Peak estradiol (E2) and number of aspirated oocytes were increased in the N-stop cycle (+16.9% and +28%, respectively), but insignificantly so. The percent of cleaving embryos was significantly increased by 27.9% (p = 0.03) in the N-stop cycle, as embryo morphology was improved by 22% (p = 0.02). The efficacy of gonadotropin treatment was enhanced in the N-stop cycle, as expressed by a 32.5% increase in oocytes retrieved per hMG ampoule administered (p = 0.04). Three cycles of 36 were cancelled during the N-stop cycle, whereas only one was cancelled in the standard protocol cycle. Of the 36 patients, 7 conceived in the N-stop protocol and 5 are ongoing pregnancies.

CONCLUSION

Discontinuation of GnRH-a during ovarian stimulation for IVF has a beneficial, but not statistically significant, effect on both E2 and oocyte production. Embryo cleavage rates and morphology were significantly improved, this may be due to improved oocyte quality, which may have been responsible for achieving pregnancies. The efficacy of gonadotropin treatment was enhanced when GnRH-a was discontinued. These results hint that GnRH-a may have a direct negative effect on folliculogenesis and oocytes, which is apparent especially in poor responder patients.

The role of gonadotropin-releasing hormone in murine preimplantation embryonic development

Previous studies have established the presence of an extrahypothalamic GnRH in a variety of tissues. GnRH receptor is known to be present in the placenta, which produces and secretes the decapeptide from the very early stages of placentation. We hypothesized that GnRH may play a role in the preimplantation development of embryos. To examine this hypothesis, we assessed GnRH and GnRH receptor messenger RNA (mRNA; RT-PCR) and protein expression (Immunohistochemistry) in preimplantation murine embryos at various developmental stages. Furthermore, preimplantation murine embryos were cultured with GnRH agonist and antagonist in vitro to assess the influence of GnRH analogs on embryo development. GnRH is expressed in the developing mouse embryo from morula to hatching blastocyst stages at the mRNA and protein levels. GnRH receptor mRNA is also present in the developing embryos studied. Preimplantation embryonic development was significantly enhanced by incubation with increasing concentrations of GnRH agonist and is significantly decreased by GnRH antagonist compared with that in the control group. Moreover, GnRH antagonist (5 and 10 microM) was able to completely block embryo development. The deleterious effect of GnRH antagonist on embryo development was reversed by increasing concentrations of the agonist, as determined by the number of embryos reaching the blastocyst stage.