Is GnRH self-priming an obligatory feature of the reproductive cycle?

Determining the optimal follicle size at trigger in patients undergoing ovarian stimulation with a clomiphene citrate plus gonadotropin and GnRH antagonist protocol for in vitro fertilization

OBJECTIVE

Determine the optimal follicle size at trigger in clomiphene citrate-based IVF protocols.

STUDY DESIGN

This is a retrospective cohort study performed in at a single academic institution that included first IVF cycles with clomiphene citrate-based protocols at our center between 01/01/2013-03/31/2019. Patients were dichotomized by whether they had ≥2 follicles >20 mm on trigger day. Group A consisted of patients with <2 follicles >20 mm on trigger day and Group B consisted of patients with ≥2 follicles >20 mm on trigger day. The primary outcome was the number of mature oocytes retrieved. Secondary outcomes included pregnancy and live birth rates.

RESULTS

A total of 635 patients were included: (Group A = 399 patients and Group B = 236 patients). The median (IQR) diameter of the largest follicle was 20.0 mm (19.0-21.0) in Group A and 22.7 mm (21.8-24.0) in Group B (p < 0.001). Among the entire cohort, mean number of oocytes retrieved was significantly higher in Group B (9.9 ± 6.5; RR 1.08 (95% CI 1.03-1.14)) compared to Group A (9.2 ± 6.3). In a subgroup analysis of patients in the upper quartile for age (≥41.7 years), Group B had significantly more oocytes retrieved (8.1 ± 5.9 vs. 6.7 ± 4.5; RR 1.23 (95% CI 1.10-1.38)), more mature oocytes retrieved (6.0 ± 4.0 vs. 5.2 ± 3.4; RR 1.16 (95% CI 1.02-1.33)), and more zygotes (4.7 ± 3.5 vs. 3.6 ± 2.8; RR 1.32 (95% CI 1.13-1.55)). In the secondary analysis, pregnancy and live birth rates after fresh transfer were similar between groups.

CONCLUSIONS

In clomiphene citrate-based IVF protocols, administering the ovulatory trigger at larger follicle sizes yielded more total oocytes retrieved without a significant difference in mature oocyte number. In older patients, larger follicle sizes at trigger yielded more mature oocytes and zygotes per retrieval. Based on these results, in older patients it may be advantageous to administer the ovulatory trigger in clomiphene-based IVF cycles when two or more follicles measures >20 mm. However, this benefit was not observed when assessed among all ages combined.

Female Reproductive Behavior

Reproductive behavior is the behavior related to the production of offspring and includes all aspects from the establishment of mating systems, courtship, sexual behavior, and parturition to the care of young. In this chapter, I outline the hormonal regulation of the estrous cycle, followed by a description of the neural regulation of female sexual behavior. Ovarian hormones play an important role in the induction of ovulation and behavioral estrus, in which they interact closely with several neurotransmitters and neuropeptides to induce sexual behavior. This chapter discusses the latest research on the role of estrogen, progesterone, serotonin, dopamine, noradrenaline, oxytocin, and GABA in female mating behavior. In addition, the most relevant brain areas, such as the preoptic area and the ventromedial nucleus of the hypothalamus, in which these regulations take place, are discussed.

A New Dawn for Intrauterine Insemination: Efficient and Prudent Practice will Benefit Patients, the Fertility Industry and the Healthcare Bodies

This review addresses the misplaced facts about the IUI procedure within a lucrative fertility industry. Evidence suggests IUI must be a first-line treatment option for most couples except in cases of bilateral tubal blockage and severe oligozoospermia. We introduce the concept of using 'consecutive ejaculation' in men with subfertility and one which can radically alter the male infertility definition, thereby providing a new approach to examining and managing male factor infertility. The review also explores various aspects affecting the IUI procedure, its determinants of success, risks and areas for future improvements. Areas such as choice of patients, clinical management of patients, the type of stimulation regime, timing and the management of sperm usage have significant bearing to whether IUI will succeed. The paper asserts that IUI should be the first choice of fertility treatment.

Gonadotropin surge-inhibiting/attenuating factors: a review of current evidence, potential applications, and future directions for research

Animal studies in the 1980s suggested the existence of an ovarian hormone, termed gonadotropin surge-inhibiting/attenuating factor (GnSIF/AF), that modulates pituitary secretion of luteinizing hormone (LH). Given the importance of identifying regulatory factors of the hypothalamic-pituitary-ovarian axis and the accumulating data suggesting its existence, we conducted a comprehensive literature search using PubMed, Web of Science, Scopus, and Embase to identify articles related to GnSIF/AF. The search generated 161 publications, of which 97 were included in this study. Several attempts have been made to identify and characterize this hormone and several candidates have been identified, but the protein sequences of these putative GnSIF/AF factors differ widely from one study to another. In addition, while the RF-amide RFRP-3 is known foremost as a neuropeptide, some research supports an ovarian origin for this non-steroidal hormone, thereby suggesting a role for RFRP-3 either as a co-modulator of GnSIF/AF or as a gonadotropin-inhibiting factor in the hypothalamus (GnIH). Discovery of the KNDy neurons that modulate GnRH secretion, on the other hand, further encourages the search for substance(s) that modulate their activity and that indirectly affect LH secretion and the hypothalamic-pituitary-ovarian axis. While it has remained an elusive hormone, GnSIF/AF holds many potential applications for contraception, in vitro fertilization, and/or cancer as well as for understanding polycystic ovary syndrome, metabolic diseases, and/or pubertal development. In this review, we rigorously examine the available evidence regarding the existence of GnSIF/AF, previous attempts at its identification, limitations to its discovery, future directions of research, and potential clinical applications.

Exogenous leptin administered intramuscularly induces sex hormone disorder and Ca loss via downregulation of Gnrh and PI3K expression

Obesity is a public health problem that increases the risk of metabolic disease, infertility, and other chronic health problems. The present study aimed to develop a new rat model for sex hormone disorder with overweight and Ca loss by intramuscular injection of exogenous leptin (LEP). Thirty female Sprague-Dawley (SD) rats (40 days old) were injected thrice intramuscularly with LEP or keyhole limpet hemocyanin immunogen. The following analyses were performed to determine the development of appetite, overweight, reproductive related-hormones, and calcium (Ca)/phosphorus (Pi) in SD rats: measurement of Lee’s index, body weight, food intake; serum Ca, Pi, and hormone tests by enzyme-linked immunosorbent analysis; histological analysis of abdominal fat; real-time polymerase chain reaction analysis of neuropeptide Y, pro-opiomelanocortin, gonadotropin-releasing hormone (Gnrh) mRNA, and gonadotropin-releasing hormone receptor (Gnrhr) mRNA expression; and western blotting analysis of enzyme phosphatidylinositol-3-kinase (PI3K). Rats injected with LEP immunogen displayed significantly increased body weight, food intake, Lee’s index, serum LEP, serum cortisol, fat deposition in the abdomen, and decreased hormones including follicle stimulating hormone, luteinizing hormone, estradiol, cholecystokinin, and Ca. Exogenous LEP administered intramuscularly also downregulate Gnrh and PI3K. In conclusion, exogenous LEP administered intramuscularly is a novel animal model for sex hormones disorder with overweight and Ca loss in SD rats. The downregulation of PI3K and Gnrh may be involved in the development of this animal model.

Human follicular fluid from superovulated women inhibits progesterone receptor-dependent gonadotropin-releasing hormone self-priming in an estrous cycle-dependent manner in the rat

These experiments investigated the involvement of gonadotrope progesterone receptor (PR) in the effects of the putative gonadotropin surge-attenuating factor (GnSAF) on gonadotropin (LH and FSH) secretion. Human follicular fluids (hFF) used in this study were aspirated from follicles in gonadotropin-treated women for in vitro fertilization. Samples were subjected to two-fold charcoal extraction of steroid hormones and two-fold inhibin immunoprecipitation. Gonadotropin secretion parameters were assessed by specific radioimmunoassays. In the first experiment, the effects of hFF on both basal and GnRH-stimulated gonadotropin secretion and GnRH self-priming were studied in incubated hemipituitaries from rats on each day of the 4-day estrous cycle. hFF inhibited only GnRH self-priming in pituitaries from rats in diestrus. In the second experiment, immunohistochemical PR expression and action were evaluated in pituitaries from rats in diestrus. PR-positive (PR10A9 antibody) gonadotropes were detected (4-5/field 40x), and antiprogestins added to the incubation media blocked the ligand-independent (GnRH) activation of PR effects on GnRH selfpriming. Finally, the third experiment evaluated the effects of hFF on P-induced potentiation of GnRH-stimulated LH secretion. GnSAF bioactivity, as evidenced by inhibition of PR-induced potentiation of GnRH-stimulated LH secretion, was found in diestrous pituitaries incubated with hFF. The results indicate that GnSAF attenuated GnRH-dependent LH secretion in diestrus through the inhibition of PR-dependent GnRH self-priming.

Why does ovarian surgery in PCOS help? Insight into the endocrine implications of ovarian surgery for ovulation induction in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex disorder with heterogeneity of clinical and endocrine features. Ovarian surgery for ovulation induction has been used in the management of clomiphene citrate-resistant anovulatory women with PCOS. Various types of ovarian surgery have been employed (wedge resection, electrocautery, laser vaporization, multiple ovarian biopsies and others) and all procedures result in an altered endocrine profile after surgery. The mechanism behind the reversal of endocrinological dysfunction in PCOS after ovarian surgery remains incompletely understood. This review scans the literature systematically to identify the endocrine changes after ovarian surgery in PCOS, in order to glean some knowledge of the mechanism involved. After ovarian surgery in PCOS, a rapid reduction in serum levels of all ovarian hormones is seen, in combination with increased serum levels of pituitary hormones. Folliculogenesis is then initiated and ovarian hormone production increases, synchronically with a reduction of pituitary hormones. Continuation of follicle growth in subsequent cycles after ovarian surgery occurs in an environment with less androgens and lower LH and FSH levels compared with pretreatment levels. The endocrine changes found after ovarian surgery in PCOS women seem to be governed by the ovaries themselves. Rapid reduced secretion of all ovarian hormones restores feedback to the hypothalamus and pituitary, resulting in appropriate gonadotrophin secretion. Initiation of follicular development seems to be induced by increasing FSH levels following a reduction of the follicle excess and (intra-ovarian) androgen levels. Additionally, anti-Müllerian hormone and gonadotrophin surge attenuating factor probably have a role in the endocrine changes.

Protein kinase C cross-talk with gonadotrope progesterone receptor is involved in GnRH-induced LH secretion

In the absence of progesterone (P), the anti-P at the receptor RU486 reduces basal and GnRH-stimulated LH secretion both in vivo and in vitro, demonstrating the existence of a ligand-independent activation of progesterone receptor (LIAPR). The aim of the present study was to determine which component of the intracellular LH secretory pathway activated by GnRH is responsible for LIAPR. To do this, anterior pituitary dispersed cells from female rats in proestrus, cultured in the presence of 17beta-estradiol, were incubated with activators or inhibitors of PKC, cAMP-PKA signalling pathways or intracellular calcium (Ca2+) traffic, in the presence or absence of RU486. Results showed that RU486 reduced both GnRH- and the PKC activator PMA-induced LH secretion. In GnRH-stimulated cells incubated with the PKC inhibitor BIS-I or treated with PMA "overnight", RU486 had no effect on reduced LH secretion, nor on stimulated LH secretion elicited by the Ca2+ ionophore ionomycin. Moreover, when GnRH- or PMA-treated cells were co-incubated with 1 microM of the L-type Ca2+ channel blocker nifedipine or the intracellular Ca2+ chelator BAPTA-AM, RU486 potentiated the expected inhibition of these drugs on LH secretion. Activation (forskolin, 8-Br-cAMP) or inhibition (MDL-12,330A) of the cAMP-PKA signalling cascade affected neither the GnRH- and PMA-induced increase of LH secretion nor the reduction of LH secretion due to RU486. Taken together, the data point to the existence of a Ca2+ -independent PKC-PR cross-talk mechanism as part of the intracellular signalling of GnRH-stimulated LH secretion.

Gonadotropin-releasing hormone (GnRH) and its natural analogues: a review

The pivotal role of gonadotropin-releasing hormone (GnRH) during the hormonal regulation of reproductive processes is indisputable. Likewise, many factors are known to affect reproductive function by influencing either GnRH release from hypothalamus or pituitary gland responsiveness to GnRH. In veterinary medicine, GnRH and its agonists (GnRHa) are widely used to overcome reduced fertility by ovarian dysfunction, to induce ovulation, and to improve conception rate. GnRHa are, moreover, integrative part of other pro-fertility treatments, e.g. for synchronization of the estrous cycle or stimulation for embryo transfer. Additionally, continuous GnRH which shows desensitizing effects of the pituitary-ovarian axis has been recommended for implementation in anti-fertility treatments like inhibition of ovulation or reversible blockade of the estrous cycle. Just as much, another group of GnRH analogues, antagonists, are now in principle disposable for use. For a few decades, GnRH was thought to be a unique structure with a primary role in regulation gonadotropins. However, it became apparent that other homologous ligands of the GnRH receptor (GnRHR) exist. In the meantime, more than 20 natural variants of the mammalian GnRH have been identified in different species which may compete for binding and/or have their own receptors. These GnRH forms (GnRHs) have apparently common and divergent functions. More studies on GnRHs should contribute to a better understanding of reproductive processes in mammals and interactions between reproduction and other physiological functions. Increased information on GnRHs might raise expectations in the application of these peptides in veterinary practice. It is the aim of this review to discuss latest results from evolutionarily based studies as well as first experimental tests and to answer the question how realistic might be the efforts to develop effective and animal friendly practical applications for endogenous GnRHs and synthetic analogues.

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.

Expression of human serum albumin (HSA) mRNA in human granulosa cells: potential correlation of the 95 amino acid long carboxyl terminal of HSA to gonadotrophin surge-attenuating factor

INTRODUCTION

According to previous studies, gonadotrophin surge-attenuating factor (GnSAF), which is assumed to be produced in human granulosa cells, has a homology with the carboxyl terminal of the human serum albumin (HSA) protein. In an attempt to validate these findings, whole or partial expression of the HSA gene was studied by RT-PCR analysis in human granulosa cells from women undergoing IVF treatment.

METHODS

RT-PCR analysis of HSA RNA transcripts in luteinized granulosa cells was done in order to investigate the possible expression of the HSA gene. To ensure the specificity of PCR products, restriction enzyme and sequence analysis were performed. Western blot analysis was carried out to detect the possible expression of the albumin gene in granulosa cells.

RESULTS

RT-PCR analysis and sequencing analysis of cDNA from granulosa cells revealed bands identical with those from the positive control for the amino as well as the carboxyl terminal corresponding to HSA gene at the cytoplasmic level.

CONCLUSION

We have demonstrated that human granulosa cells express the carboxyl and amino terminal part of the HSA gene in levels comparable to those found in human hepatocytes. It is suggested that the coding gene for GnSAF may be a result of an alternative expression of HSA gene.

No Evidence for Pituitary Priming to Gonadotropin-Releasing Hormone in Relation to Luteinizing Hormone (LH) Secretion Prior to the Preovulatory LH Surge in Ewes1

The purpose of this study was to determine the occurrence of and the regulatory mechanisms involved in priming of the pituitary to GnRH before the preovulatory LH surge in sheep. Experiment 1: Forty-two ewes had progestagen devices removed after 14 days and were assigned to luteal (Lut) or follicular (Foll) groups. Fifteen days later, blood sampling was initiated either immediately or 36 h after induced luteolysis in groups Lut and Foll, respectively. After 4 h, ewes were administered either saline (n = 5) or 250 ng (n = 8) or 10 microg (n = 8) of GnRH. Five ewes per treatment group were killed 1 h later, while remaining animals were blood sampled for a further 7 h. Experiment 2: Eighteen ewes were allocated to Lut and Foll groups (described above). Blood samples were collected from 2 h before GnRH (10 microg) treatment until 7 h after. Despite up-regulated GnRH-R mRNA levels in Foll ewes, pituitary content and plasma levels of LH and LHbeta mRNA levels were similar between groups. Mean FSHbeta mRNA and plasma FSH levels were elevated in Lut ewes but declined after GnRH treatment. Inversely, plasma estradiol and inhibin-A concentrations were higher in Foll ewes and declined after GnRH treatment. Fewer LH(+ve)/secretogranin II(-ve) (SgII(-ve)) granules were present in gonadotropes of Foll ewes, coincident with increased basal LH levels. Fewer smaller sized granules were present after GnRH treatment. In conclusion, there was no evidence of self-priming before onset of the preovulatory LH surge. Constitutive release of LH(+ve)/SgII(-ve) granules may maintain basal LH levels while smaller sized, presumably mature granules may be preferentially released after GnRH stimulation.

Gonadotrophin stimulation reduces VEGF(120) expression in the mouse uterus during the peri-implantation period

BACKGROUND

Ovarian stimulation by gonadotrophin treatment exerts negative effects on implantation and embryonic development. We investigated whether gonadotrophin treatment affects VEGF(120) mRNA expression during the peri-implantation period.

METHODS

Two groups of adult female CD1 mice were used: the hormone-treated group was injected i.p. with urinary human FSH (5 IU in 0.1 ml saline) and urinary HCG (5 IU in 0.1 ml saline). Spontaneously ovulating mice served as controls and received saline injections. The pregnant mice were killed on embryonic development (ED) days 0, 3, 4, 5 and 6 (day of vaginal plug detection is considered as ED0). The uteri with the implanted embryos were processed for in-situ hybridization for VEGF(120). A separate group of control and hormone-treated pregnant mice were allowed to give birth. Litter size, birthweight and length of gestational period were noted.

RESULTS

Gonadotrophin treatment decreased VEGF(120) mRNA levels, delayed implantation, reduced the size of the embryo implantation site on ED5 and ED6 and prolonged the gestational period.

CONCLUSIONS

Gonadotrophin treatment reduces VEGF(120) expression which may have serious consequences for normal embryonic development. The present data cannot establish whether this effect is a cause or consequence of delayed implantation.