Facilitation or inhibition of the oestradiol-induced gonadotrophin surge in the immature female rat by progesterone: effects on pituitary responsiveness to gonadotrophin-releasing hormone (GnRH), GnRH self-priming and pituitary mRNAs for the progesterone receptor A and B isoforms

Comparison of progesterone protocol versus gonadotropin-releasing hormone antagonist protocol in terms of preventing premature LH surge and assisted reproductive technology outcome in infertile women: a randomized controlled trial

INTRODUCTION

Progesterone can be used instead of GnRH agonists and antagonists in order to avert a premature LH surge during controlled ovarian stimulation (COS) protocol. Nonetheless, there is limited knowledge regarding its utilization. Thus, this study compared the effects of progesterone and GnRH antagonists (GnRH-ant) on premature LH surges and assisted reproductive technology (ART) results in infertile women undergoing ART.

MATERIALS AND METHODS

In this clinical trial, the progesterone protocol (study group) and GnRH-ant protocol (control group) were tested in 300 infertile individuals undergoing IVF/ICSI. The main outcome was the number of oocytes retrieved. The secondary outcomes included premature LH rise/surge, the quantity of follicles measuring ≥ 10 and 14 mm, oocyte maturity and fertilization rate, the number of viable embryos, high-quality embryo rate and pregnancy outcomes.

RESULTS

The study group exhibited a statistically significant increase in the number of retrieved oocytes, follicles measuring 14 mm or greater, and viable embryos compared to the control group (P < 0.05). The study group also increased oocyte maturity, chemical pregnancy rate, and clinical pregnancy rate (P < 0.05). Both groups had similar mean serum LH, progesterone, and E2 levels on trigger day. The control group had more premature LH rise than the study group, although this difference was not statistically significant.

CONCLUSION

In conclusion, it can be stated that the progesterone protocol and the GnRH-ant protocol exhibit similar rates of sudden premature LH surge in infertile patients. However, it is important to note that the two regiments differ in their outcomes in ART.

TRIAL REGISTRATION

This study was retrospectively registered in the Iranian website ( www.irct.ir ) for clinical trials registration ( http://www.irct.ir : IRCT-ID: IRCT20201029049183N, 2020-11-27).

Comparison of Cumulative Live Birth Rates between Flexible and Conventional Progestin-Primed Ovarian Stimulation Protocol in Poor Ovarian Response Patients According to POSEIDON Criteria: A Cohort Study

RESEARCH QUESTION

To compare the cumulative live birth rate (CLBR) per oocyte retrieval cycle of a conventional progestin-primed ovarian stimulation (cPPOS) regimen with a flexible progestin-primed ovarian stimulation (fPPOS) regimen in poor ovarian response patients, according to POSEIDON criteria.

DESIGN

Poor ovarian response women, according to POSEIDON criteria, who underwent the first PPOS protocol for in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) between January 2018 and December 2020 were included. The fPPOS group involved 113 participants, and the cPPOS group included 1119 participants. In the cPPOS group, medroxyprogesterone acetate (MPA) (10 mg/d) was administrated on the gonadotropin injection the same day as gonadotropin injections in the cPPOS group, while MPA was started either on the day when the leading follicle with mean diameter > 12mm was present and/or serum E2 was >300 pg/mL in the fPPOS protocol group. The primary outcome was CLBR.

RESULTS

The fPPOS protocol had higher CLBR per oocyte retrieval cycle compared to the cPPOS group, even without a statistically significant difference (29.6% vs. 24.9%, p = 0.365). The fPPOS group had fewer numbers of retrieved oocytes (2.87 ± 2.03 vs. 3.76 ± 2.32, p < 0.001) but a higher MII oocyte rate (89.8% vs. 84.7%, p = 0.016). In addition, the number of available embryos in the two groups was comparable (1.37 ± 1.24 vs. 1.63 ± 1.38, p = 0.095). There were five women in the fPPOS group, and 86 women in the cPPOS group had a premature LH surge (4.2% vs. 6.8%, p = 0.261). In the fPPOS group, there was one instance of premature ovulation, while in the cPPOS group, there were six occurrences of premature ovulation (0.8 vs. 0.5%, p = 1.000).

CONCLUSION(S)

The novel fPPOS protocol appears to achieve higher CLBR even without significant differences and with MPA consumption compared with cPPOS protocol in low-prognosis patients.

Progestin-Primed Ovarian Stimulation Protocol for Patients in Assisted Reproductive Technology: A Meta-Analysis of Randomized Controlled Trials

Objectives

Progestin-primed ovarian stimulation (PPOS) is a new ovarian stimulation protocol that can block the luteinizing hormone (LH) surge through progesterone instead of traditional down regulating or gonadotropin-releasing hormone (GnRH) antagonist, and in order to achieve multi-follicle recruitment. This paper aims to investigate the effectiveness of PPOS and its suitability for infertile patients with different ovarian reserve functions.

Methods

We searched published randomized controlled trials (RCTs) about PPOS on Cochrane Library, PubMed, Embase, and Web of Science. The search period spanned from January 1, 2015 to November 16, 2020. The data were extracted, and the meta-analysis was performed on ovarian stimulation as well as embryological and clinical outcomes. The outcomes were pooled by a random effects model, and the risk of heterogeneity was evaluated. Subgroup analysis was performed for different ovarian reserve patients.

Results

The clinical pregnancy rates and live birth or ongoing pregnancy rates with the PPOS protocol were not different from those with the control group. In the diminished ovarian reserve (DOR) subgroup, the PPOS protocol had a lower rate of premature LH surge [RR = 0.03, 95% CI = 0.01 to 0.13, p < 0.001]. The PPOS protocol had a lower rate of ovarian hyperstimulation syndrome (OHSS) [RR = 0.52, 95% CI = 0.36 to 0.76, p < 0.001, I2 = 0.00%]. The secondary outcomes showed that the number of oocytes retrieved, MII oocytes, and viable embryos was higher than that of the control protocol in DOR patients [(MD = 0.33, 95% CI = 0.30 to 0.36, p < 0.001), (MD = 0.30, 95% CI = 0.27 to 0.33, p < 0.001), (MD = 0.21, 95% CI = 0.18 to 0.24, p < 0.001)] and normal ovarian reserve (NOR) patients [(MD = 1.41, 95% CI = 0.03 to 2.78, p < 0.001), (MD = 1.19, 95% CI = 0.04 to 2.35, p < 0.001), (MD = 1.01, 95% CI = 0.21 to 1.81, p = 0.01)].

Conclusion

The findings suggest that PPOS is an effective ovarian stimulation protocol and is beneficial for patients with different ovarian reserve functions, which needs to be validated in more RCTs with larger samples.

Progestin vs. Gonadotropin-Releasing Hormone Antagonist for the Prevention of Premature Luteinizing Hormone Surges in Poor Responders Undergoing in vitro Fertilization Treatment: A Randomized Controlled Trial

Objective: Progestin was recently used as an alternative of gonadotropin-releasing hormone (GnRH) analog for preventing premature luteinizing hormone (LH) surge with the aid of vitrification techniques, however, limited data were available about the potential of progestin in poor responders undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment. We performed a randomized parallel controlled trial to investigate the difference of progestin and GnRH antagonist in poor responders. Methods: A total of 340 poor responders who met with Bologna criteria were randomly allocated into the progestin-primed ovarian stimulation (PPOS) group and GnRH antagonist group. Fresh embryo transfer was preferred in the GnRH antagonist group and freeze-all was performed in the PPOS group. The primary outcome was the incidence of premature LH surge, secondary outcomes were the number of retrieved oocytes, the number of viable embryos and the pregnancy outcomes. Results: The results showed that the incidence of premature LH surge in PPOS group was lower than that in antagonist group (0 vs. 5.88%, P < 0.05). In PPOS group, the average numbers of oocytes and viable embryos were comparable to those in GnRH antagonist group (3.7 ± 2.6 vs. 3.4 ± 2.4; 1.6 ± 1.7 vs. 1.4 ± 1.3, P > 0.05), the live birth rate was similar between the two groups (21.8 vs. 18.2%, RR 1.25 (95% confidence interval 0.73, 2.13), P > 0.05). Conclusions: The study demonstrated that PPOS had a more robust control for preventing premature LH rise than GnRH antagonist in poor responders, but PPOS in combination with freeze-all did not significantly increase the probability of pregnancy than GnRH antagonist protocol for poor responders.

Gonadotropin-releasing hormone antagonist versus progestin for the prevention of premature luteinising hormone surges in poor responders undergoing in vitro fertilisation treatment: study protocol for a randomised controlled trial

BACKGROUND

Progress in vitrification techniques has allowed reproductive physicians to consider new strategies for using progestin as an alternative to a GnRH analogue to improve in vitro fertilisation (IVF). However, the role of progestin in blocking luteinising hormone (LH) surges and its potential in clinical practice are unclear, especially for poor responders. We designed a prospective randomised controlled trial (RCT) to compare the efficacy of a gonadotropin-releasing hormone (GnRH) antagonist and progestin in blocking LH surges and premature ovulation in poor responders.

METHODS/DESIGN

Poor responders who meet the Bologna criteria will be randomised to one of two stimulation regimens-gonadotropin-releasing hormone (GnRH) antagonist or progestin-primed ovarian stimulation (PPOS)-using a computer-generated random number. Fresh embryos were transferred in the GnRH antagonist group and frozen embryos were transferred in the PPOS group. The primary outcome is the incidence of premature LH surges. Secondary outcomes include the number of oocytes retrieved, the number of embryos available for transfer, implantation rates and clinical pregnancy. The sample size for this trial is estimated as 340 participants, with 170 participants in each group. The data analysis will be by intention to treat.

DISCUSSION

To our knowledge, this is the first RCT to examine the efficacy of administering progestin orally to block LH surges and premature ovulation compared with the GnRH antagonist protocols in poor responders undergoing IVF treatment.

TRIAL REGISTRATION

www.chictr.org.cn . ChiCTR-IPR-17010906 . Registered on 18 March 2017.

60 YEARS OF NEUROENDOCRINOLOGY: MEMOIR: Harris' neuroendocrine revolution: of portal vessels and self-priming

Geoffrey Harris, while still a medical student at Cambridge, was the first researcher (1937) to provide experimental proof for the then tentative view that the anterior pituitary gland was controlled by the CNS. The elegant studies carried out by Harris in the 1940s and early 1950s, alone and in collaboration with John Green and Dora Jacobsohn, established that this control was mediated by a neurohumoral mechanism that involved the transport by hypophysial portal vessel blood of chemical substances from the hypothalamus to the anterior pituitary gland. The neurohumoral control of anterior pituitary secretion was proved by the isolation and characterisation of the 'chemical substances' (mainly neuropeptides) and the finding that these substances were released into hypophysial portal blood in a manner consistent with their physiological functions. The new discipline of neuroendocrinology - the way that the brain controls endocrine glands and vice versa - revolutionised the treatment of endocrine disorders such as growth and pubertal abnormalities, infertility and hormone-dependent tumours, and it underpins our understanding of the sexual differentiation of the brain and key aspects of behaviour and mental disorder. Neuroendocrine principles are illustrated in this Thematic Review by way of Harris' major interest: hypothalamic-pituitary-gonadal control. Attention is focussed on the measurement of GnRH in hypophysial portal blood and the role played by the self-priming effect of GnRH in promoting the onset of puberty and enabling the oestrogen-induced surge or pulses of GnRH to trigger the ovulatory gonadotrophin surge in humans and other spontaneously ovulating mammals.

Understanding the regulation of pituitary progesterone receptor expression and phosphorylation

Administration of human FSH (hFSH) during the diestrus phase in cyclic rats is followed by a reduction in the preovulatory LH surge. This inhibitory action of FSH involves a decrease in the stimulatory effect of gonadotrope progesterone receptor (PR) activation, in a ligand-dependent (progesterone) and -independent (GNRH) manner. PR activation and action are mandatory for LH surge, and are dependent on the phosphorylation of serine (Ser) residues. Together with this post-translational modification, PR is marked for downregulation by proteasome machinery. These experiments used the western blotting technique to measure pituitary expression of PR-A and PR-B isoforms and phosphorylation levels of Ser294 and Ser400 PR-B in rats bearing i) hFSH treatment or ii) PR downregulation. Treatment with hFSH reduced LH secretion and increased that of estradiol in proestrus afternoon. hFSH injections, without altering PR-A and PR-B content or ratio, caused a reduction in phosphorylation of Ser294 and Ser400 but only when pituitaries were previously challenged with progesterone or GNRH for 2 h. However, while pSer294 levels increased after 2 h of pituitary incubation with progesterone or GNRH, those of pSer400 were not modified by thesein vitrotreatments. Finally, progesterone had a biphasic effect: in 2-h incubations increased pituitary PR-A and PR-B content, but after 8 h caused downregulation and altered PR-A:PR-B ratio. The results provide a potential mechanism through which LH levels are decreased by hFSH administration and better understanding of the control of PR expression and phosphorylation in rat pituitaries.

Estrous behavior in dairy cows: identification of underlying mechanisms and gene functions

Selection in dairy cattle for a higher milk yield has coincided with declined fertility. One of the factors is reduced expression of estrous behavior. Changes in systems that regulate the estrous behavior could be manifested by altered gene expression. This literature review describes the current knowledge on mechanisms and genes involved in the regulation of estrous behavior. The endocrinological regulation of the estrous cycle in dairy cows is well described. Estradiol (E2) is assumed to be the key regulator that synchronizes endocrine and behavioral events. Other pivotal hormones are, for example, progesterone, gonadotropin releasing hormone and insulin-like growth factor-1. Interactions between the latter and E2 may play a role in the unfavorable effects of milk yield-related metabolic stress on fertility in high milk-producing dairy cows. However, a clear understanding of how endocrine mechanisms are tied to estrous behavior in cows is only starting to emerge. Recent studies on gene expression and signaling pathways in rodents and other animals contribute to our understanding of genes and mechanisms involved in estrous behavior. Studies in rodents, for example, show that estrogen-induced gene expression in specific brain areas such as the hypothalamus play an important role. Through these estrogen-induced gene expressions, E2 alters the functioning of neuronal networks that underlie estrous behavior, by affecting dendritic connections between cells, receptor populations and neurotransmitter releases. To improve the understanding of complex biological networks, like estrus regulation, and to deal with the increasing amount of genomic information that becomes available, mathematical models can be helpful. Systems biology combines physiological and genomic data with mathematical modeling. Possible applications of systems biology approaches in the field of female fertility and estrous behavior are discussed.

Estrogen regulation of gene expression in GnRH neurons

Estrogen plays an essential role in the regulation of the female reproductive hormone axis, and specifically is a major regulator of GnRH neuronal function in the female brain. GnRH neuronal cell lines were used to explore the direct effects of estradiol on gene expression in GnRH neurons. The presence of estrogen receptor (ER) binding sites was established by a receptor-binding assay, and estrogen receptor alpha and beta mRNA were identified in GN11 cells and ERbeta in GT1-7 cells using RT-PCR analysis of mRNA. ERalpha was more abundantly expressed in GN11 cells than ERbeta as assessed by real-time PCR. Additionally, GN11 cells expressed significantly more of both ERalpha and beta than GT1-7 cells. Functional studies in GN11 and GT1-7 demonstrated estrogen down regulation of endogenous mouse GnRH mRNA levels using quantitative real-time PCR (qRT-PCR). Correspondingly, estradiol also reduced secretion of GnRH from both the GN11 and GT1-7 cell lines. Since estradiol has been shown to regulate progesterone receptor (PR) expression; similar studies were performed demonstrating an estradiol mediated increase in PR in both cell lines. Estradiol regulation of ER expression was also explored and these studies indicated that estradiol decreased ERalpha and ERbeta mRNA levels in a dose-dependent manner in GN11 and GT1-7 cells. These effects were blocked by the addition of the estrogen receptor antagonist ICI 182,780. Both PPT, a specific ERalpha agonist, and DPN, a specific ERbeta agonist, inhibited GnRH gene expression in GN11 cells, but only DPN inhibited GnRH gene expression in GT1-7 cells, consistent with their undetectable levels of ERalpha expression. These studies characterize a direct inhibitory effect of estradiol on GnRH in GnRH neurons, and a direct stimulatory effect of estradiol on PR gene expression. In addition, the agonist studies indicate that there is a functional overlap of ERalpha and ERbeta regulation in GnRH neurons. These studies may give insight into the molecular regulation of estrogen negative feedback in the central reproductive axis.