GnRH analogues: applications in assisted reproductive techniques

GnRH agonists: Updating fixed-time artificial insemination protocols in sows

Protocols for fixed-time artificial insemination (FTAI) in swine reproduction can help increase genetic improvement and production efficiency. Different gonadotropin-releasing hormone (GnRH) agonists have been developed to gain better control of follicular development, timing, and ovulation quality; therefore, they have been extensively used in FTAI protocols. This literature review resumes the most important characteristics of the physiology of follicular development and ovulation in sows, followed by a discussion about the hormonal alternatives available to induce ovulation (human chorionic gonadotropin, hCG; porcine luteinizing hormone, LH and GnRH agonists). Also, ovulation induction failures with GnRH agonists are described. Finally, current FTAI protocols with GnRH agonists are resumed and discussed. FTAI with GnRH agonists has proven to be an efficient, successful reproductive protocol that can be implemented in pig farms due to better knowledge of an endocrine system that regulates follicular development and ovulation and increased availability of several GnRH agonists that allow more efficient reproductive swine programs.

The LH endocrine profile in gonadotropin-releasing hormone analogue cycles

Research question: What does the evolution of serum luteinizing hormone (LH) levels look like throughout the follicular phase of cycles in which gonadotrophins and gonadotropin-releasing hormone (GnRH) analogues in the context of ovarian stimulation for assisted reproduction technologies (ART) were used?Design: This was a retrospective, observational cohort study in a tertiary infertility clinic. 1303 patients aged between 18 and 43 years of age were included with a total of 2200 cycles for ART, using GnRH-analogues for pituitary down-regulation stimulated with human menopausal gonadotropin (hMG) or recombinant follicle stimulating hormone (rec-FSH). Follicular evolution of LH during ovarian stimulation in different treatment protocols was modeled as repeated measures.Results: LH evolution showed a significant decrease in antagonist/hMG cycles of 0.17 IU/L per day (95% CI [-0.20, -0.12]) and 0.26 IU/L per day in rec-FSH cycles (95% CI [-0.29, -0.22]). This decrease was significantly stronger in rec-FSH cycles than in hMG cycles (estimated difference of 0.09 IU/L per day, 95% CI [0.04, 0.15]). Short agonist/hMG cycles showed a significant increase in LH of 0.04 IU/L per day (95% CI [0.01, 0.08]), while the increase of 0.01 IU/L per day in cycles with rec-FSH was not significant (95% CI [-0.08, 0.10]).Conclusion: Follicular evolution of LH during controlled ovarian stimulation differs between different GnRH analogue cycles. A statistically significant decrease in LH was shown in GnRH antagonist cycles being more pronounced with rec-FSH compared to hMG. This decrease in LH in antagonist cycles and the potential impact on estradiol levels and follicle growth needs further examination.

Luteinizing hormone supplementation in women with hypogonadotropic hypogonadism seeking fertility care: Insights from a narrative review

The management of infertile women affected by hypogonadotropic hypogonadism (HH) or conditions mimicking it is particularly challenging. In the present narrative review, we aimed to synthesize the available evidence on the benefit (if any) of exogenous luteinizing hormone (LH) supplementation in this group of patients. Available data support LH supplementation in women with organic or functional HH. On the contrary, the benefit of exogenous LH on reproductive outcomes both in advanced maternal age patients and in cases of depletion of FSH and LH levels induced by GnRH analogues has not been demonstrated. unfortunately, the inhomogeneous study populations as well as the methodological heterogeneity between studies focused on women affected by conditions mimicking HH do not allow reliable conclusions to be drawn.

Dydrogesterone versus medroxyprogesterone acetate co-treatment ovarian stimulation for IVF: a matched cohort study of 236 freeze-all-IVF cycles

This matched cohort study was retrospectively performed, with cycles extracted from freeze-all-IVF treatments performed between March and November 2019, to compare the efficacy of flexible-start dydrogesterone (DYG) co-treatment ovarian stimulations (OS) with flexible-start medroxyprogesterone acetate (MPA) co-treatment OS. DYG cycles were matched 1:1 with MPA cycles using female age and antral follicle count, resulting in 236 matched cycles. OS durations and total FSH doses were similar in DYG and MPA OS cycles. The numbers of mature oocytes retrieved were similar; however, the mature oocyte retrieval rate was significantly lower (66.7 vs. 78.2%; p = .001) and the cycle cancellation rates were higher (29.2 vs. 21.2%; p = .056) in DYG co-treatments. A linear regression selected OS co-treatment protocol (0.53 DYG (0.356-0.776), p = .001) into the final model to predict a ≥ 80% mature oocyte retrieval rate. The per transfer (47.2 vs. 49.7; p = .721) and per treatment ongoing pregnancy rates (32.2 vs. 38.1%, p = .210) were similar in the two co-treatment groups. Flexible-start DYG co-treatment OS was as effective in blastocyst freeze-all-IVF cycles as MPA co-treatment, with similar ongoing pregnancy rates; however, mature oocyte retrieval was significantly decreased and cycle cancellation increased in DYG cycles.Impact statementWhat is already known on this subject? Progestin (i.e. artificial progesterone) co-treatment has long been known to be a feasible alternative to conventional GnRH-analogue co-treatment in OS for IVF, because of the long-standing evidence that progestin formulations have in oral contraceptive therapies. The recent evolution of effective freeze-all-IVF (in which high mid-cycle progesterone levels is not of concern because of the postponement of embryo transfer) has now made it possible to investigate progestin co-treatment OS in IVF.What do the results of this study add? Ongoing pregnancy rates from blastocyst frozen embryo transfers in flexible-start dydrogesterone (DYG) co-treatment ovarian stimulation (OS) cycles were similar to rates in flexible-start medroxyprogesterone acetate (MPA) co-treatment OS cycles. The mature oocyte retrieval rate was significantly lower and the cycle cancellation rate higher in DYG than in MPA cycles.What are the implications of these findings for clinical practice and/or further research? The evidence suggests that MPA co-treatment should be preferred in OS for IVF. Further investigation is required to refine progestin co-treatment protocols, because of their potential to reduce the number of viable blastocysts.

Medroxyprogesterone acetate used in ovarian stimulation is associated with reduced mature oocyte retrieval and blastocyst development: a matched cohort study of 825 freeze-all IVF cycles

PURPOSE

To compare the effectivity of flexible-start medroxyprogesterone acetate (MPA) co-treatment ovarian stimulations (OS) with flexible-start gonadotropin-releasing hormone antagonist (GnRH-ant) co-treatment OS, in blastocyst freeze-all IVF cycles.

METHOD

This matched cohort study was performed at a single IVF center. Study cycles were extracted from freeze-all IVF cycles performed between February 2015 and June 2018 with cycles grouped according to the co-treatment protocol (MPA and GnRH-ant groups) used. MPA cycles were matched 1:1 using antral follicle count, female age, infertility duration, and female body mass index, with GnRH-ant cycles, resulting in 825 matched cycles. MPA or CET co-treatment was started when leading follicles reached 11-12 mm.

RESULTS

Duration of OS was significantly longer, and total FSH dose was significantly higher in the MPA group. Numbers of mature oocytes retrieved were similar; however, the mature oocyte retrieval rate (83.8 vs. 97.1%; p < 0.001), number of blastocysts, blastocyst rate (36.4 vs. 41.4%; p < 0.001) and > 2 viable blastocyst rate were all significantly lower in the MPA group. The live birth (LB) per transfer rates (51.6 vs. 55.7%; p = 0.155) were similar; however, the LB rate per treatment was significantly lower (40.9 vs. 45.8%; p = 0.05). A linear regression included the OS co-treatment protocol (GnRH-ant; 1.4 (1.07-1.81); p = 0.013) in the final model to predict having > 2 viable blastocysts.

CONCLUSION

Flexible-start MPA co-treatment OS was as effective in freeze-all IVF cycles as GnRH-ant co-treatment, with similar LB per transfer rates; however, increased cycle cancellation and reduced blastocyst numbers reduced LB per treatment rates significantly.

Recent advancements in the hormonal stimulation of ovulation in swine

Induction of ovulation for controlled breeding is available for use around the world, and conditions for practical application appear promising. Many of the hormones available, such as human chorionic gonadotropin (hCG), gonadotropin-releasing hormone (GnRH) and its analogs, as well as porcine luteinizing hormone (pLH), have been shown to be effective for advancing or synchronizing ovulation in gilts and weaned sows. Each of the hormones has unique attributes with respect to the physiology of its actions, how it is administered, its efficacy, and approval for use. The timing for induction of ovulation during the follicle phase is critical as follicle maturity changes over time, and the success of the response is determined by the stage of follicle development. Female fertility is also a primary factor affecting the success of ovulation induction and fixed time insemination protocols. Approximately 80%-90% of female pigs will develop mature follicles following weaning in sows and synchronization of estrus in gilts. However, those gilts and sows with follicles that are less developed and mature, or those that develop with abnormalities, will not respond to an ovulatory surge of LH. To address this problem, some protocols induce follicle development in all females, which can improve the overall reliability of the ovulation response. Control of ovulation is practical for use with fixed time artificial insemination and should prove highly advantageous for low-dose and single-service artificial insemination and for use with frozen-thawed and sex-sorted sperm.

Comparison of pregnancy rates in beef cattle after a fixed-time AI with once- or twice-used controlled internal drug release devices

The use of fixed-time artificial insemination (FTAI) provides producers with numerous benefits including the use of superior genetics, shorter breeding and calving seasons, and a more uniform calf crop. However, the cost of implementing FTAI protocols is one of the several drawbacks hindering their use in the beef industry. Potential injection-site lesions from intramuscular injections of the hormones necessary for estrus synchronization are also a cause of concern for carcass quality. The objectives of this experiment were to (1) determine whether or not a twice-used controlled internal drug release (CIDR) device would be effective in an FTAI protocol without adversely affecting pregnancy rate and (2) whether or not the subcutaneous administration of PGF2α affects pregnancy rate. Nulliparous females (n = 99) between 13 and 27 months of age and multiparous cows (n = 43) between 48 and 74 months of age were synchronized for estrus using the 7-day CO-Synch + CIDR protocol. The females were randomly assigned to one of the two treatments: (1) a once-used CIDR (control) or (2) a twice-used CIDR device (treatment) incorporated into their synchronization protocol. The females were also randomly assigned to have their injection of PGF2α administered either intramuscularly or subcutaneously. Blood was taken in a random subset of nulliparous females (n = 52) just before device removal and assayed for concentration of progesterone. The concentration of progesterone was higher (P = 0.01) in the animals that received once-used CIDR devices than that in those received twice-used CIDR devices (3.4 ± 0.5 and 1.4 ± 0.5 ng/mL, respectively). There was no significant effect of parity (P = 0.82), artificial insemination technician (P = 0.60), PGF2α administration (P = 0.83), or treatment (P = 0.67) on pregnancy rates to artificial insemination which were 75.4 ± 6.0% and 71.7 ± 6.4%, for animals that received once- and twice-used CIDR devices, respectively. This study provides evidence that although concentration of progesterone is decreased in animals treated with a twice-used CIDR device, there is still a sufficient release of progesterone from the device to effectively synchronize estrus without adversely affecting the fertility of a herd.

A biomimetic approach for enhancing the in vivo half-life of peptides

The tremendous therapeutic potential of peptides has not yet been realized, mainly due to their short in vivo half-life. While conjugation to macromolecules has been a mainstay approach for enhancing the half-life of proteins, the steric hindrance of macromolecules often harms the binding of peptides to target receptors, compromising the in vivo efficacy. Here we report a new strategy for enhancing the in vivo half-life of peptides without compromising their potency. Our approach involves endowing peptides with a small-molecule that binds reversibly to the serum protein, transthyretin. Although there are few reversible albumin-binding molecules, we are unaware of designed small molecules that bind reversibly to other serum proteins and are used for half-life extension in vivo. We show here that our strategy was indeed effective in enhancing the half-life of an agonist for GnRH receptor while maintaining its binding affinity, which was translated into superior in vivo efficacy.

Folliculogenesis Is Not Fully Inhibited during GnRH Analogues Treatment in Mice Challenging Their Efficiency to Preserve the Ovarian Reserve during Chemotherapy in This Model

As many chemotherapy regimens induce follicular depletion, fertility preservation became a major concern in young cancer patients. By maintaining follicles at the resting stage, gonadotropin-releasing hormone analogues (GnRHa) were proposed as an ovarian-protective option during chemotherapy. However, their efficacy and mechanisms of action remain to be elucidated. Mice were dosed with cyclophosphamide (Cy, 100–500mg/kg i.p) to quantify follicular depletion and evaluate apoptosis at different times. We observed a dose-dependent depletion of the follicular reserve within 24 hours after Cy injection with a mean follicular loss of 45% at the dose of 200mg/kg. Apoptosis occurs in the granulosa cells of growing follicles within 12 hours after Cy treatment, while no apoptosis was detected in resting follicles suggesting that chemotherapy acutely affects both resting and growing follicles through different mechanisms. We further tested the ability of both GnRH agonist and antagonist to inhibit oestrus cycles, follicular growth and FSH secretion in mice and to protect ovarian reserve against chemotherapy. Although GnRHa were efficient to disrupt oestrus cycles, they failed to inhibit follicular development, irrespective of the doses and injection sites (sc or im). Around 20% of healthy growing follicles were still observed during GnRHa treatment and serum FSH levels were not reduced either by antagonist or agonist. GnRHa had no effect on Cy-induced follicular damages. Thus, we showed that GnRHa were not as efficient at inhibiting the pituitary-gonadal axis in mice as in human. Furthermore, the acute depletion of primordial follicles observed after chemotherapy does not support the hypothesis that the ovary may be protected by gonadotropin suppression.

Medical treatment for adenomyosis and/or adenomyoma

Uterine adenomyosis and/or adenomyoma is characterized by the presence of heterotopic endometrial glands and stroma within the myometrium, >2.5 mm in depth in the myometrium or more than one microscopic field at 10 times magnification from the endometrium-myometrium junction, and a variable degree of adjacent myometrial hyperplasia, causing globular and cystic enlargement of the myometrium, with some cysts filled with extravasated, hemolyzed red blood cells, and siderophages. Hysterectomy is a "gold standard" and definitive therapy for uterine adenomyosis, and many cases of adenomyosis have been diagnosed by pathological review retrospectively. As such, the diagnosis of adenomyosis is difficult, and this subsequently results in difficulty in the management of these patients, especially those who are symptomatic but have a strong desire to preserve their uterus. In our previous review, we found that the use of uterine-sparing surgery in the management of uterine adenomyosis and/or adenomyoma is still controversial, although some data support its feasibility. Conservative treatment is still needed in the group of patients that requires preservation of fertility and improvement of quality of life. However, studies focusing on the topic of medical treatment for adenomyosis are rare. In this article, current knowledge regarding the use of medical therapy for uterine adenomyosis, partly based on the understanding of endometriosis, is reviewed.

Is measurement of progesterone level prior to FSH stimulation useful in GnRH-antagonist cycles?

AIM

To reduce patient inconvenience during in vitro fertilization (IVF) cycles, some protocols delay intensive monitoring until mid-follicular stimulation. Others assess hormone levels prior to follicle-stimulating hormone (FSH) administration, not commencing stimulation until baseline progesterone (P4) levels (< 5 nmol/l) are achieved. Higher P4 levels (> 4.8 nmol/L) on the day of FSH trigger have been implicated in poorer pregnancy rates. This study evaluates the association of P4 levels at day 1-2 in gonadotrophin-releasing hormone (GnRH)-antagonist cycles with pre-trigger P4 levels and clinical pregnancy rates (CPRs).

METHOD

All fresh GnRH-antagonist IVF cycles between June 2011 and June 2012, in which pre-FSH P4 levels were not routinely performed (group 1), were retrieved from the IVF Australia database and compared with controls (group 2).

RESULTS

There were 163 cycles in each group. P4 levels on the day of trigger were significantly higher in group 1 (3.75 vs. 2.77, p < 0.05). The incidence of pre-trigger P4 levels >4.8 nmol/l was significantly higher in group 1 (30 vs. 16, p < 0.05). The number of oocytes retrieved was higher in group 1 (11.1 vs. 9, p < 0.05), however fertilization rates were significantly lower in that group (53.6% vs. 61.2%, p < 0.05); CPRs were similar between the two groups (27.8% vs. 31.8%, p = ns). Overall, pregnancy rates were lower in cycles with pre-trigger P4 level of > 4.8 nmol/L compared with those with lower levels (15% vs. 32.5%, p < 0.05).

CONCLUSION

We found that measurement of P4 level at early follicular phase was associated with significantly lower pre-trigger levels. However, this did not translate into a difference in CPR between the monitored and unmonitored groups. We have confirmed that elevation in pre-trigger P4 level is associated with halving of the CPR, indicating that the most important P4 measurements are those in the late follicular/pre-trigger phase.

Milestones in contraceptive vaccines development and hurdles in their application

Contraceptive vaccines have been proposed for controlling the growing human population and wildlife population management. Multiple targets such as gonadotropin releasing hormone (GnRH), luteinizing hormone, follicle stimulating hormone, gonadotropin receptors, sperm-specific proteins and zona pellucida glycoproteins have been exploited to develop contraceptive vaccine and their efficacy investigated and shown in various experimental animal models. Vaccines based on GnRH have found application in immuno-castration of male pigs for prevention of boar-taint. Vaccines based on zona pellucida glycoproteins have shown promising results for population management of wild horses and white-tailed deer. Phase II clinical trials in women with β-human chorionic gonadotropin (β-hCG)-based contraceptive vaccine established proof of principle that these can be developed for human application. Block in fertility by β-hCG contraceptive vaccine was reversible. Further research inputs are required to establish the safety of contraceptive vaccines, improve their immunogenicity and to develop novel vaccine delivery platforms for providing long lasting immunity.

Estrus synchronization and ovarian hyper-stimulation treatments have negligible effects on cumulus oocyte complex gene expression whereas induction of ovulation causes major expression changes

The effects of exogenous hormones, used for estrus synchronization and ovarian hyper stimulation, on cumulus oocyte complexes (COCs) gene expression in sexually mature rats were determined using microarrays. Gene expression in COCs collected from GnRH (G(trt)), GnRH + eCG (G + E(trt)), and GnRH + eCG + hCG (G + E + H(trt)) treatments were compared to COCs from naturally cycling (NC) rats before the preovulatory luteninizing hormone surge. There was no significant difference in gene expression among NC, G(trt), and G + E(trt); however, over 2,600 genes were significantly different between NC and G + E + H(trt) (P < 0.05). Genes upregulated in G + E + H(trt) encode for: proteins that are involved in prostaglandin synthesis (Ptgs2, Pla2g4a, and Runx1) and cholesterol biosynthesis (Hmgcr, Sc4mol, and Dhcr24); receptors that allow cholesterol uptake (Ldlr and Scarb1), regulate progesterone synthesis (Star), and inactivate estrogen (Sult1e1); and downstream effectors of LH signal (Pgr, Cebpb, Creb3l1, Areg, Ereg, and Adamts1). Conversely, G + E + H(trt) downregulated genes encoding proteins involved in: DNA replication and cell cycle progression (Ccne2, Orc5l, Rad50, and Mcm6); reproductive developmental process; and granulosa cell expansion (Gdf9, Bmp15, Amh, Amhr2, Bmpr1b, Tgfb2, Foxl2, Pde3a, Esr2, Fshr, Ybx2, Ccnd2, Ccnb1ip1, and Zp3); maternal effect genes required for embryo development (Zar1, Npm2, Nlrp5, Dnmt1, H1foo, and Zfp57); amino acid degradation; and ketogenesis (Hmgcs2, and Cpt1b). These results from the rat show that hormones used for estrus synchronization (G(trt)) and ovarian hyper stimulation (G + E(trt)) had minimal effects on gene expression, whereas induction of ovulation (G + E + H(trt)) caused major changes in gene expression of rat COCs. This study provides comprehensive information about regulated genes during late follicle development and ovulation induction.

Cumulus cells gene expression profiling in terms of oocyte maturity in controlled ovarian hyperstimulation using GnRH agonist or GnRH antagonist

In in vitro fertilization (IVF) cycles controlled ovarian hyperstimulation (COH) is established by gonadotropins in combination with gonadotropin-releasing hormone (GnRH) agonists or antagonists, to prevent premature luteinizing hormone (LH) surge. The aim of our study was to improve the understanding of gene expression profile of cumulus cells (CC) in terms of ovarian stimulation protocol and oocyte maturity. We applied Affymetrix gene expression profiling in CC of oocytes at different maturation stages using either GnRH agonists or GnRH antagonists. Two analyses were performed: the first involved CC of immature metaphase I (MI) and mature metaphase II (MII) oocytes where 359 genes were differentially expressed, and the second involved the two GnRH analogues where no differentially expressed genes were observed at the entire transcriptome level. A further analysis of 359 differentially genes was performed, focusing on anti-Müllerian hormone receptor 2 (AMHR2), follicle stimulating hormone receptor (FSHR), vascular endothelial growth factor C (VEGFC) and serine protease inhibitor E2 (SERPINE2). Among other differentially expressed genes we observed a marked number of new genes connected to cell adhesion and neurotransmitters such as dopamine, glycine and γ-Aminobutyric acid (GABA). No differential expression in CC between the two GnRH analogues supports the findings of clinical studies where no significant difference in live birth rates between both GnRH analogues has been proven.

Influence of estrogen levels on thermal perception, pain thresholds, and pain tolerance: studies on women undergoing in vitro fertilization

We examined the relationship between estrogen and pain in women undergoing in vitro fertilization (IVF). Quantitative sensory tests (QST) were performed twice during the IVF-regimen: once during hormonal down-regulation and once during hormonal up-regulation. A group of healthy men and a group of women using monophasic contraceptives were also examined, to control for session-to-session effects. Among the women undergoing IVF, serum 17β-estradiol levels differed strongly between treatments as expected, and increased from 65.7 (SD = 26) pmol/L during the down-regulation phase, to 5,188 (SD = 2,524) pmol/L during the up-regulation phase. Significant outcomes in the QST were only seen for temperature perception thresholds (1.7 °C versus 2.2 °C; P = .003) and cold pain threshold (11.5 °C versus 14.5 °C; P = .04). A similar change in cold pain threshold was also seen in the 2 control groups, however, and statistical analysis suggested that this change was due to a session-to-session effect rather than being the result of hormonal modulation. Heat pain thresholds, heat tolerance, pressure pain thresholds, and the cold pressor test showed no significant differences between sessions. These data demonstrate that pain perception and pain thresholds in healthy women show little, if any, changes even with major variations in serum estradiol levels.

PERSPECTIVE

This study shows that pain perception and tolerance in women undergoing in vitro fertilization do not vary, despite the dramatic changes in 17β-estradiol levels induced by the treatment regimen. The result thus suggests that in humans, contrary to experimental animals, changes in estrogen levels have little influence on pain sensitivity.

Association of controlled ovarian hyperstimulation treatment with down-regulation of key regulators involved in embryonic implantation in mice

The debate exists whether or not gonadotropin-releasing hormone (GnRH) analogs used in controlled ovarian hyperstimulation (COH) impair endometrial receptivity. Homeobox A11 (Hoxa11), Meis homeobox 1 (Meis1), cadherin 1 (Cdh1), and catenin beta 1 (Ctnnb1) are well known to be involved in successful implantation. In this study, the endometrial expression of Hoxa11, Meis1, Cdh1, and Ctnnb1 during the peri-implantation period was investigated in an in vitro fertilization (IVF) mouse model by real-time RT-PCR and Western blot to evaluate the relationship between Hoxa11, Meis1, Cdh1, and Ctnnb1 expression and the impact of the COH on endometrial receptivity. The mimic COH protocols included GnRH agonist plus human menopausal gonadotropin (HMG) (GnRH agonist group), GnRH antagonist plus HMG (GnRH antagonist group), and HMG alone (HMG group). The expression levels of Hoxa11, Meis1, Cdh1, and Ctnnb1 mRNA and protein were decreased in all of the COH groups. The expression levels of Hoxa11 and Ctnnb1 were the lowest in the GnRH agonist group, and those of Meis1 and Cdh1 were lower in the GnRH analog groups than the HMG group. There were positive correlations between the expression of Hoxa11 and Ctnnb1, as well as the expression of Meis1 and Cdh1 among all the groups. In conclusion, the COH protocols, particularly with GnRH analogs, suppressed Hoxa11, Meis1, Ctnnb1 and Cdh1 expression, in mouse endometrium during the peri-implantation period. Our data reveal a novel molecular mechanism by which the COH protocols might impair endometrial receptivity.

Role of gender in multiple sclerosis: clinical effects and potential molecular mechanisms

Multiple sclerosis (MS) is more prevalent in females than males, and this female predominance is increasing as time goes by. Additionally, gender appears to play critical roles in development, progression and treatment of MS, and is therefore an aspect that should always be considered in the design and interpretation of research and clinical trials for MS. In this review, factors that could potentially explain the gender-biased observations in MS are discussed. These include sex-specific differences between the male and female immune systems and nervous systems, genetic and epigenetic or environmental-related effects, the effects of gonadal hormones, and materno-fetal interactions.

Observational Study to Assess the Therapeutic Value of Four Ovarian Hyperstimulation Protocols in IVF After Pituitary Suppression with GnRH Antagonists in Normally Responding Women

Objective

To compare the clinical results of four different protocols of COH for IVF-ICSI in normovulatory women, using in all cases pituitary suppression with GnRH antagonists.

Materials/methods

A single center, open label, parallel-controlled, prospective, post-authorization study under the approved conditions for use where 305 normal responders women who were candidates to COH were assigned to r-FSH +hp-hMG (n = 51, Group I), hp-hMG (n = 61, Group II), fixed-dose r-FSH (n = 118, Group III), and r-FSH with potential dose adjustment (n = 75, Group IV) to subsequently undergo IVF-ICSI.

Results

During stimulation, Group IV needed significantly more days of stimulation as compared to Group II [8.09 ± 1.25 vs. 7.62 ± 1.17; P < 0.05], but was the group in which more oocytes were recovered [Group I: 9.43 ± 4.99 vs. Group II: 8.96 ± 4.82 vs. Group III: 8.78 ± 3.72 vs. Group IV: 11.62 ± 5.80; P < 0.05]. No significant differences were seen between the groups in terms of clinical and ongoing pregnancy, but among patients in whom two embryos with similar quality parameters (ASEBIR) were transferred, the group treated with hp-hMG alone achieved a significantly greater clinical pregnancy rate as compared to all other groups [Group I: 31.6%, Group II: 56.4%, Group III: 28.7%, Group IV: 32.7%; P < 0.05].

Conclusions

Although randomized clinical trials should be conducted to achieve a more reliable conclusion, these observations support the concept that stimulation with hp-hMG could be beneficial in normal responders women undergoing pituitary suppression with GnRH antagonists.

Milder is better? Advantages and disadvantages of "mild" ovarian stimulation for human in vitro fertilization

In the last decades, several steps have been made aiming at rendering human IVF more successful on one side, more tolerable on the other side. The "mild" ovarian stimulation approach, in which a lower-than-average dose of exogenous gonadotropins is given and gonadotropin treatment is started from day 2 to 7 of the cycle, represents a significant step toward a more patient's friendly IVF. However, a clear view of its virtues and defects is still lacking, because only a few prospective randomized trials comparing "mild" vs. conventional stimulation exist, and they do not consider some important aspects, such as, e.g., thawing cycles. This review gives a complete panorama of the "mild" stimulation philosophy, showing its advantages vs. conventional ovarian stimulation, but also discussing its disadvantages. Both patients with a normal ovarian responsiveness to exogenous gonadotropins and women with a poor ovarian reserve are considered. Overall, we conclude that the level of evidence supporting the use of "mild" stimulation protocols is still rather poor, and further, properly powered prospective studies about "mild" treatment regimens are required.

The impact of ovarian stimulation for IVF on the developing embryo

The use of assisted reproductive technologies (ART) has been increasing over the past three decades, and, in developed countries, ART account for 1-3% of annual births. In an attempt to compensate for inefficiencies in IVF procedures, patients undergo ovarian stimulation using high doses of exogenous gonadotrophins to allow retrieval of multiple oocytes in a single cycle. Although ovarian stimulation has an important role in ART, it may also have detrimental effects on oogenesis, embryo quality, endometrial receptivity and perinatal outcomes. In this review, we consider the evidence for these effects and address possible underlying mechanisms. We conclude that such mechanisms are still poorly understood, and further knowledge is needed in order to increase the safety of ovarian stimulation and to reduce potential effects on embryo development and implantation, which will ultimately be translated into increased pregnancy rates and healthy offspring.

GnRH antagonist, cetrorelix, for pituitary suppression in modern, patient-friendly assisted reproductive technology

BACKGROUND

Gonadotropin-releasing hormone (GnRH) analogues are used routinely to prevent a premature luteinizing hormone (LH) surge in women undergoing assisted reproductive technology (ART) treatments. In contrast to GnRH agonists, antagonists produce rapid and reversible suppression of LH with no initial flare effect.

OBJECTIVE

To review the role of cetrorelix, the first GnRH antagonist approved for the prevention of premature LH surges during controlled ovarian stimulation in modern ART.

METHOD

A review of published literature on cetrorelix.

RESULTS

Both multiple- and single-dose cetrorelix protocols were shown to be at least as effective as long GnRH agonist regimens for pituitary suppression in Phase II/III clinical trials. Furthermore, cetrorelix co-treatment resulted in similar live birth rates but a shorter duration of gonadotropin stimulation, a lower total gonadotropin dose requirement and lower incidence of ovarian hyperstimulation syndrome compared with long agonist regimens. A single-dose cetrorelix protocol further decreased the number of injections required. Preliminary studies have also produced promising data on the use of cetrorelix in modified ART protocols, such as frozen embryo transfer and donor oocyte recipient cycles.

CONCLUSION

Cetrorelix offers a potential therapeutic alternative to GnRH agonists during controlled ovarian stimulation and has become an integral part of modern, patient-friendly reproductive medicine.

Synthesis of chemically modified bioactive peptides: recent advances, challenges and developments for medicinal chemistry

Although not complying with Lipinski’s rule, peptides are to an increasing extent being developed into new active pharmaceutical ingredients. This is mainly due to novel application routes, formulations and chemical modifications, which confer on the peptides improved uptake and increased metabolic stability. A brief survey of currently approved peptide drugs and the present scope of the application of peptides as drugs is provided. Cyclic peptides are emerging as an interesting class of peptides with conformational rigidity and homogeneity, high receptor affinity and selectivity, increased metabolic stability and – in special cases – even oral availability. Challenges and new methodology for the synthesis of cyclic peptides are outlined and an overview of approaches toward the design of peptide conformation and peptide modification by nonproteinogenic building blocks is given.