Stimulatory and inhibitory effects of progesterone on follicular development in the hypophysectomized follicle-stimulating hormone/luteinizing hormone-treated hamster

Multi-omics reveal the metabolic patterns in mouse cumulus cells during oocyte maturation

Bi-directional communication between cumulus cells and the surrounded oocytes is important for the development and functions of both compartments. However, the metabolic framework in cumulus cells has not been systematically described. In the present study, cumulus cells from cumulus-oocyte complexes (COCs) at three key time points were isolated (arrested GV stage, post-hCG 0h; meiotic resumption GVBD stage, post-hCG 3h; and metaphase II stage, post-hCG 12h), and the temporal metabolomic and proteomic profiling were performed. Integrated multi-omics analysis reveals the global metabolic patterns in cumulus cells during mouse oocyte maturation. In particular, we found the active hyaluronic acid metabolism, steroid hormone synthesis, and prostaglandin E2 (PGE2) production in cumulus cells. Meanwhile, accompanying the oocyte maturation, a progressive increase in nucleotide and amino acid metabolism was detected in the surrounding cumulus cells. In sum, the data serve as a valuable resource for probing metabolism during terminal differentiation of ovarian granulosa cells, and provide the potential biomarkers for improving and predicting oocyte quality.

Progestin Primed Ovarian Stimulation (PPOS) protocol yields lower euploidy rate in older patients undergoing IVF

BACKGROUND

To explore if exogenous progestin required for progestin primed ovarian stimulation (PPOS) protocol compromises the euploidy rate of patients who underwent preimplantation genetic testing cycles when compared to those who received the conventional gonadotropin-releasing hormone (GnRH) antagonist protocol.

METHODS

This retrospective cohort study analyzed 128 preimplantation genetic testing for aneuploidy (PGT-A) cycles performed from January 2018 to December 2021 in a single university hospital-affiliated fertility center. Infertile women aged 27 to 45 years old requiring PGT-A underwent either PPOS protocol or GnRH-antagonist protocol with in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) for fertilization. Frozen embryo transfers were performed following each PGT-A cycle. Data regarding the two groups were analyzed using the Statistical Package for Social Sciences (SPSS) version 22.0 (SPSS Inc., Chicago, IL).

RESULTS

Patients who underwent PPOS treatment had significantly reduced blastocyst formation rate and euploidy rate compared to those who received the GnRH antagonist protocol. Subgroup-analysis was performed by stratifying patients' age into elder and young subgroups (elder: ≥ 38-year-old, young: < 38-year-old). In the elder sub-population, the blastocyst formation rate of the PPOS group was significantly lower than that of the GnRH-antagonist group (45.8 ± 6.1% vs. 59.9 ± 3.8%, p = 0.036). Moreover, the euploidy rate of the PPOS group was only about 20% of that of  the GnRH-antagonist group (5.4% and 26.7%, p = 0.006). In contrast, no significant differences in blastocyst formation rate (63.5 ± 5.7% vs. 67.1 ± 3.2%, p = 0.45) or euploidy rate (30.1% vs. 38.5%, p = 0.221) were observed in the young sub-population. Secondary outcomes, which included implantation rate, biochemical pregnancy rate, clinical pregnancy rate, live birth rate, and miscarriage rate, were comparable between the two treatment groups, regardless of age.

CONCLUSION

When compared to the conventional GnRH-antagonist approach, PPOS protocol could potentially reduce the euploidy rate in aging IVF patients. However, due to the retrospective nature of this study, the results are to be interpreted with caution. Before the PPOS protocol is widely implemented, further studies exploring its efficacy in larger populations are needed to define the optimal patient selection suitable for this method.

TRIAL REGISTRATION

Human Investigation and Ethical Committee of Chang Gung Medical Foundation (202200194B0).

Progesterone Signaling and Mammalian Ovarian Follicle Growth Mediated by Progesterone Receptor Membrane Component Family Members

How progesterone influences ovarian follicle growth is a difficult question to answer because ovarian cells synthesize progesterone and express not only the classic nuclear progesterone receptor but also members of the progestin and adipoQ receptor family and the progesterone receptor membrane component (PGRMC) family. Which type of progestin receptor is expressed depends on the ovarian cell type as well as the stage of the estrous/menstrual cycle. Given the complex nature of the mammalian ovary, this review will focus on progesterone signaling that is transduced by PGRMC1 and PGRMC2 specifically as it relates to ovarian follicle growth. PGRMC1 was identified as a progesterone binding protein cloned from porcine liver in 1996 and detected in the mammalian ovary in 2005. Subsequent studies focused on PGRMC family members as regulators of granulosa cell proliferation and survival, two physiological processes required for follicle development. This review will present evidence that demonstrates a causal relationship between PGRMC family members and the promotion of ovarian follicle growth. The mechanisms through which PGRMC-dependent signaling regulates granulosa cell proliferation and viability will also be discussed in order to provide a more complete understanding of our current concept of how progesterone regulates ovarian follicle growth.

Progesterone affects clinic oocyte yields by coordinating with follicle stimulating hormone via PI3K/AKT and MAPK pathways

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Progesterone reduced oocyte yields in clinic. Yields were rescued by the higher dose of hMG.

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Progesterone downregulated follicle growth and consequently reduced oocyte yields.

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Progesterone inhibited granular cell proliferation via MAPK and PI3K/AKT pathways.

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Progesterone and FSH coordinated follicle growth via signalling crosstalk in granular cells.

Introduction

As an effective inhibitor of premature ovulation, progestin was introduced to a novel ovarian stimulation regimen for infertility treatment. However, the local action of progestin on the ovary and its effect on clinical outcomes have not been described.

Objectives

The influence of progesterone administration on clinical oocyte outcomes and the mechanisms involved in the coordination of progesterone and follicle stimulating hormone (FSH) on follicle growth and oocyte yields were investigated.

Methods

Clinical outcomes of patients undergoing ovarian stimulation for in vitro fertilization were analyzed. The murine ovarian stimulation model and follicle culture system were used to evaluate the effects of progesterone on oocyte yield, follicle development, granular cell proliferation, and hormone secretion. Phospho-specific protein microarrays were used to explore involved signaling pathways.

Results

Progesterone decreased clinical oocyte yields, and yields were rescued with an increased dose of human menopausal gonadotropin. Administration of progesterone inhibited murine granular cell proliferation and reduced the growth rate of follicles; both of which were rescued by FSH. The phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT) and mitogen-activated protein kinase (MAPK) were identified as pivotal signaling pathways to integrate progesterone into the FSH signaling network in granular cells.

Conclusion

Progesterone inhibited granular cell proliferation and antral follicle growth during ovarian stimulation, and subsequently influenced oocyte outcomes in the clinical setting. Progesterone coordinated with FSH to regulate follicle growth through PI3K/AKT and MAPK signaling pathways. These findings advance our knowledge regarding the ovarian response to gonadotropins during progestin-primed ovarian stimulation and create an opportunity to manipulate individual oocyte yields.

The flavonoid, kaempferol-3-O-apiofuranosyl-7-O-rhamnopyranosyl, as a potential therapeutic agent for breast cancer with a promoting effect on ovarian function

It is widely known that breast cancer cells eventually develop resistance to hormonal drugs and chemotherapies, which often compromise fertility. This study aimed to investigate the effect of the flavonoid, kaempferol-3-O-apiofuranosyl-7-O-rhamnopyranosyl (KARP), on 1) the viability of MCF-7 breast cancer cells and 2) ovarian function in rats. A dose-dependent decrease in MCF-7 cell survival was observed, and the IC50 value was found to be 48 μg/ml. Cells in the control group or those exposed to increasing concentrations of KARP experienced a similar generation of reactive oxygen species and induction of apoptosis. For the rats, estradiol levels correlated negatively to KARP dosages, although a recovery was obtained at administration of 30 mg/kg per day. Noteworthily, when compared against the control, this dosage led to significant increases in mRNA levels for CYP19, CYP17a, CCND2, GDF9, and INSL3 among the treatment groups, and ER1 and ER2 mRNA levels decreased in a dose-dependent manner. KARP shows great promise as an ideal therapy for breast cancer patients since it induced apoptosis and autophagy in cancerous cells without harming fertility in our animal model. Future investigations on humans are necessary to substantiate these findings and determine its efficacy as a general line of treatment.

Assessing recrudescence of photoregressed Siberian hamster ovaries using in vitro whole ovary culture

In vitro culture has been used to study different aspects of ovarian function; however, this technique has not been applied to study recrudescence, or the return of ovarian function in seasonally breeding species. In Siberian hamsters, exposure to inhibitory photoperiods induces declines in ovarian function, which are restored with photostimulation. Because these changes are mediated by changes in systemic gonadotropin (GT) secretion, we hypothesized that culturing photoregressed ovaries with GT would restore aspects of function and induce expression of key folliculogenic factors. Adult female Siberian hamsters were exposed to either long-day (LD; 16L:8D) or short-day (SD; 8L:16D) photoperiods for 14 weeks to maintain in vivo cyclicity or induce gonadal regression, respectively. Isolated ovaries were then cultured for 10 days with or without GT. Ovarian mass and messenger RNA (mRNA) expression of mitotic marker Pcna were increased in cultured SD ovaries (cSD) ovaries with GT as compared to without GT, with no changes noted among cultured LD (cLD) ovaries. Media estradiol and progesterone concentrations increased in both cLD and cSD ovaries cultured with GT as compared to without GT. No differences in follicle numbers or incidence of apoptosis were noted across groups. In addition, differential mRNA expression of folliculogenic growth factors ( Bmp-4, Ntf-3, Inh-α, Gdf-9, Igf-1, Has-2, and Cox-2) was observed in cSD treated with or without GT. Together, these results suggest that this in vitro model could be a useful tool to (a) study the return of function in photoregressed ovaries, and (b) to identify the specific roles folliculogenic factors play in ovarian recrudescence.

Relationship between time post-ovulation and progesterone on oocyte maturation and pregnancy in canine cloning

Canine oocytes ovulated at prophase complete meiosis and continue to develop in presence of a high progesterone concentration in the oviduct. Considering that meiotic competence of canine oocyte is accomplished in the oviductal environment, we postulate that hormonal milieu resulting from the circulating progesterone concentration may affect oocyte maturation and early development of embryos. From 237 oocyte donors, 2620 oocytes were collected and their meiotic status and morphology were determined. To determine optimal characteristics of the mature oocytes subjected to nuclear transfer, a proportion of the meiotic status of the oocytes were classified in reference to time post-ovulation as well as progesterone (P4) level. A high proportion of matured oocytes were collected from >126h (55.5%) post-ovulation or 40-50ngmL^-1 (46.4%) group compared to the other groups. Of the oocyte donors that provided mature oocytes in vivo, there was no correlation between serum progesterone of donors and time post ovulation, however, time post-ovulation were significantly shorter for <30ng/mL group (P<0.05). Using mature oocytes, 1161 cloned embryos were reconstructed and transferred into 77 surrogates. In order to determine the relationship between pregnancy performance and serum progesterone level, embryos were transferred into surrogates showing various P4 serum levels. The highest pregnancy (31.8%) and live birth cloning efficacy (2.2%) rates were observed when the embryos were transferred into surrogates with circulating P4 levels were from 40 to 50ngmL^-1. In conclusion, measurement of circulating progesterone of female dog could be a suitable an indicator of the optimal time to collect quality oocyte and to select surrogates for cloning.

Expression of progesterone receptor membrane component-2 within the immature rat ovary and its role in regulating mitosis and apoptosis of spontaneously immortalized granulosa cells

Progesterone receptor membrane component 2 (Pgrmc2) mRNA was detected in the immature rat ovary. By 48 h after eCG, Pgrmc2 mRNA levels decreased by 40% and were maintained at 48 h post-hCG. Immunohistochemical studies detected PGRMC2 in oocytes and ovarian surface epithelial, interstitial, thecal, granulosa, and luteal cells. PGRMC2 was also present in spontaneously immortalized granulosa cells, localizing to the cytoplasm of interphase cells and apparently to the mitotic spindle of cells in metaphase. Interestingly, PGRMC2 levels appeared to decrease during the G1 stage of the cell cycle. Moreover, overexpression of PGRMC2 suppressed entry into the cell cycle, possibly by binding the p58 form of cyclin dependent kinase 11b. Conversely, Pgrmc2 small interfering RNA (siRNA) treatment increased the percentage of cells in G1 and M stage but did not increase the number of cells, which was likely due to an increase in apoptosis. Depleting PGRMC2 did not inhibit cellular (3)H-progesterone binding, but attenuated the ability of progesterone to suppress mitosis and apoptosis. Taken together these studies suggest that PGRMC2 affects granulosa cell mitosis by acting at two specific stages of the cell cycle. First, PGRMC2 regulates the progression from the G0 into the G1 stage of the cell cycle. Second, PGRMC2 appears to localize to the mitotic spindle, where it likely promotes the final stages of mitosis. Finally, siRNA knockdown studies indicate that PGRMC2 is required for progesterone to slow the rate of granulosa cell mitosis and apoptosis. These findings support a role for PGRMC2 in ovarian follicle development.

Non-canonical progesterone signaling in granulosa cell function

It has been known for over 3 decades that progesterone (P4) suppresses follicle growth. It has been assumed that P4 acts directly on granulosa cells of developing follicles to slow their development, as P4 inhibits both mitosis and apoptosis of cultured granulosa cells. However, granulosa cells of developing follicles of mice, rats, monkeys, and humans do not express the A or B isoform of the classic nuclear receptor for P4 (PGR). By contrast, these granulosa cells express other P4 binding proteins, one of which is referred to as PGR membrane component 1 (PGRMC1). PGRMC1 specifically binds P4 with high affinity and mediates P4's anti-mitotic and anti-apoptotic action as evidenced by the lack of these P4-dependent effects in PGRMC1-depleted cells. In addition, mice in which PGRMC1 is conditionally depleted in granulosa cells show diminished follicle development. While the mechanism through which P4 activation of PGRMC1 affects granulosa cell function is not well defined, it appears that PGRMC1 controls granulosa cell function in part by regulating gene expression in T-cell-specific transcription factor/lymphoid enhancer factor-dependent manner. Clinically, altered PGRMC1 expression has been correlated with premature ovarian failure/insufficiency, polycystic ovarian syndrome, and infertility. These collective studies provide strong evidence that PGRMC1 functions as a receptor for P4 in granulosa cells and that altered expression results in compromised reproductive capacity. Ongoing studies seek to define the components of the signal transduction cascade through which P4 activation of PGRMC1 results in the regulation of granulosa cell function.

Progesterone receptor membrane component 1 and its role in ovarian follicle growth

Progesterone (P4) is synthesized in the ovary and acts directly on granulosa cells of developing ovarian follicles to suppress their rate of mitosis and apoptosis. Granulosa cells do not express nuclear progesterone receptor (PGR) but rather progesterone receptor membrane component-1 (PGRMC1). PGRMC1 binds P4 and mediates P4's actions, as evidenced by PGRMC1 siRNA studies. PGRMC1 acts by binding plasminogen activator inhibitor 1 RNA-binding protein and regulating gene expression. Specifically, PGRMC1 suppresses some genes that promote cell death (i.e., Bad, Caspase-3, Caspase-4). P4 regulates gene expression in part by inhibiting PGRMC1 binding to Tcf/Lef transcription sites, thereby reducing Tcf/Lef transcriptional activity. Since Tcf/Lef transcription sites are located within the promoters of genes that initiate mitosis and/or apoptosis (i.e., c-jun and c-myc), P4-PGRMC1 mediated suppression of these Tcf/Lef regulated genes could account for P4's actions. PGRMC1 expression is also altered in women with polycystic ovarian syndrome, premature ovarian failure and infertility. Collectively, these observations support a role for PGRMC1 in regulating human ovarian follicle development.

Multiplicity of Progesterone's Actions and Receptors in the Mammalian Ovary1

This minireview summarizes the role that progesterone (P4) plays in regulating granulosa and luteal cell function. These actions include the stimulation of P4 synthesis and the inhibition of estrogen synthesis, mitosis, and apoptosis. P4 also plays a key role in the ovulatory process. Although P4's actions are well documented, the mechanism or mechanisms that mediate all of these actions have not been defined. In addition to P4-induced gene transcription that is mediated by the nuclear P4 receptors (PGR-A and PGR-B), three other receptor/signal transduction pathways could account for P4's intraovarian actions. These pathways could be mediated by 1) the PGR localizing at or near the plasma membrane and activating SRC family kinases, 2) a membrane progestin receptor that responds to P4 by lowering intracellular cAMP and increasing MAPK 3/1 activity, and 3) a membrane receptor complex composed of serpine 1 mRNA binding protein (also known as PAIRBP1 or RDA288) and progesterone receptor membrane component 1. Ligand activation of this complex likely leads to an increase in protein kinase G activity, the maintenance of low basal intracellular free calcium, and the inhibition of granulosa and luteal cell mitosis and apoptosis. Given the complexity of P4's actions within the ovary, it is likely that all of these receptor/signal transduction pathways influence some aspect of ovarian function with the specific P4 response dependent on 1) the expression pattern of these putative P4 receptors, 2) the P4 binding affinity of each receptor system, and 3) the amount of available P4.

Localization of the progesterone receptor in the porcine ovary

Regulation of progesterone receptor (PR) expression has been studied in many species. However, precise studies have not yet been performed in the porcine ovary. We have examined the localization of PR in follicles and corpora lutea of the porcine ovary at different stages of their development. The effects of LH and FSH on PR expression in granulosa cells of small antral follicles was also studied. Immunohistochemistry was applied to determine the distribution of PR while immunoblot analysis showed that two isoforms A and B were present. Early antral follicles contained PR in the granulosa layer. In granulosa cells of small and medium antral follicles PR was not detected whereas it was present in the theca layer. Before ovulation, PR was found in both granulosa and theca cells of large follicles and the staining intensity was very strong. FSH or LH treatment of small follicles (100 ng/ml) induced changes in cellular distribution patterns of PR. In both cases, PR was expressed in granulosa cells. PR was detected in corpora lutea in all 3 stages of the luteal phase. Our data show that in the pig ovary changes in PR localization are stage-specific and suggest that expression of PR is positively regulated by both LH and FSH.

Dynamics of ovarian follicular development in cattle following hysterectomy and during early pregnancy

Three experiments were conducted to evaluate ovarian follicular dynamics and functional activity during pregnancy in cattle. In 11 pregnant Charolais cows of Experiment I, size of largest follicle, number of follicles and accumulated follicle size were reduced by day 27 of pregnancy on the ovary bearing the corpus luteum (CL) but not on the non-CL bearing ovary. In experiment II, local attenuation of ovarian follicular development on the CL bearing ovary of seven pregnant heifers was evident compared to the contralateral ovary without the CL. However, in four hysterectomized heifers, follicular development was sustained on both the CL- and non-CL bearing ovaries when CL maintenance was achieved without presence of the uterus or conceptus. In Experiment III, steroidogenic characteristics of the largest and second largest follicles at 17 d postestrus were evaluated for seven pregnant and six cyclic cattle. Follicle by physiological status interactions were detected for both aromatase activity of the follicle and follicular fluid concentrations of estradiol and progesterone. In cyclic cows, the largest follicle had appreciably more aromatase activity than did the second largest follicle; whereas, aromatase activity of the largest follicle from pregnant cows was less than that of cyclic cows. However, in pregnant cows the second largest follicle became the estrogen-active follicle, and this follicle occurred with a higher frequency on the ovary contralateral to the CL-bearing ovary. These changes in aromatase activity were reflected by parallel changes in estrogen concentrations of follicular fluid. The higher progesterone concentration in follicular fluid of the largest follicle in pregnant cows provided further confirmation of their atretic status. In conclusion, during early pregnancy the conceptus and/or uterus ipsilateral to the conceptus appear to secrete compounds which alter local follicular steroidogenic activity and attenuate subsequent follicular growth between 17 to 34 d of pregnancy on the CL-bearing ovary. This local mechanism acting within the ovary may contribute to the antiluteolytic effects of early pregnancy in cattle.

Immunohistochemical localization of oestrogen receptors and progesterone receptors in the human ovary throughout the menstrual cycle

Immunohistochemistry was used to determine the distribution of oestrogen receptors (ER) and progesterone receptors (PR) in the human ovary during folliculogenesis. Primordial and preantral follicles did not contain ER or PR. The granulosa cells of antral follicles had ER, but negligible PR, before the LH surge. In contrast, at the time of LH surge, these cells of the dominant follicle contained PR, but not ER. On the other hand, granulosa cells of the non-dominant follicles had ER, but not PR. After ovulation, the PR persisted in the luteinized granulosa cells and in the corpus luteum during early pregnancy. The theca interna and surrounding stromal cells were ER-negative and PR-positive throughout the menstrual cycle. Thus, the results show that ER and PR are not expressed simultaneously in the granulosa cells, the thecal cells, or the stromal cells during folliculogenesis. Mechanisms controlling the expression of steroid receptors during the normal menstrual cycle and in early pregnancy are discussed.

Histological assessment of follicular development and its applicability to risk assessment

The objective of this article is to describe histological methods currently used to study ovarian physiology that may have applicability to reproductive toxicology. Histologic techniques are, for the most part, inexpensive and easy to perform. Many of these techniques require little equipment and can be readily implemented in small laboratories. The resulting histological preparations are permanent, can be used over again for several different types of analyses, and provide objective, quantifiable endpoints. These techniques have been extremely useful for studying the ovary.