Pharmacologic production of luteinized unruptured follicles by prostaglandin synthetase inhibitors

New insights into the ovulatory process in the human ovary

BACKGROUND

Successful ovulation is essential for natural conception and fertility. Defects in the ovulatory process are associated with various conditions of infertility or subfertility in women. However, our understanding of the intra-ovarian biochemical mechanisms underlying this process in women has lagged compared to our understanding of animal models. This has been largely due to the limited availability of human ovarian samples that can be used to examine changes across the ovulatory period and delineate the underlying cellular/molecular mechanisms in women. Despite this challenge, steady progress has been made to improve our knowledge of the ovulatory process in women by: (i) collecting granulosa cells across the IVF interval, (ii) creating a novel approach to collecting follicular cells and tissues across the periovulatory period from normally cycling women, and (iii) developing unique in vitro models to examine the LH surge or hCG administration-induced ovulatory changes in gene expression, the regulatory mechanisms underlying the ovulatory changes, and the specific functions of the ovulatory factors.

OBJECTIVE AND RATIONALE

The objective of this review is to summarize findings generated using in vivo and in vitro models of human ovulation, with the goal of providing new insights into the mechanisms underlying the ovulatory process in women.

SEARCH METHODS

This review is based on the authors' own studies and a search of the relevant literature on human ovulation to date using PubMed search terms such as 'human ovulation EGF-signaling', 'human ovulation steroidogenesis', 'human ovulation transcription factor', 'human ovulation prostaglandin', 'human ovulation proteinase', 'human ovulation angiogenesis' 'human ovulation chemokine', 'human ovulatory disorder', 'human granulosa cell culture'. Our approach includes comparing the data from the authors' studies with the existing microarray or RNA-seq datasets generated using ovarian cells obtained throughout the ovulatory period from humans, monkeys, and mice.

OUTCOMES

Current findings from studies using in vivo and in vitro models demonstrate that the LH surge or hCG administration increases the expression of ovulatory mediators, including EGF-like factors, steroids, transcription factors, prostaglandins, proteolytic systems, and other autocrine and paracrine factors, similar to those observed in other animal models such as rodents, ruminants, and monkeys. However, the specific ovulatory factors induced, their expression pattern, and their regulatory mechanisms vary among different species. These species-specific differences stress the necessity of utilizing human samples to delineate the mechanisms underlying the ovulatory process in women.

WIDER IMPLICATIONS

The data from human ovulation in vivo and in vitro models have begun to fill the gaps in our understanding of the ovulatory process in women. Further efforts are needed to discover novel ovulatory factors. One approach to address these gaps is to improve existing in vitro models to more closely mimic in vivo ovulatory conditions in humans. This is critically important as the knowledge obtained from these human studies can be translated directly to aid in the diagnosis of ovulation-associated pathological conditions, for the development of more effective treatment to help women with anovulatory infertility or, conversely, to better manage ovulation for contraceptive purposes.

REGISTRATION NUMBER

N/A.

Follicular fluid and plasma lipidome profiling and associations towards embryonic development outcomes during ART treatment

Introduction

It is well acknowledged that lipids assume a critical role in oocyte maturation and early embryonic metabolism, this study aimed to evaluate the relationship between the lipid composition of plasma and follicular fluid (FF), and the consequences of embryonic development. This study compared the lipidomic profiles of paired plasma and FF samples obtained from sixty-five Chinese women who underwent assisted reproductive technology (ART) treatments.

Methods

Non-targeted lipidomics analysis.

Result

Results not only indicated similarities in lipid composition between these biofluids, but also revealed a number of unique differences. The biomatrix distinction was found to be primarily driven by lipids belonging to the lysophosphatidylcholines (LPC), phosphatidylethanolamines (PE), ether PE, and triglyceride (TG) classes. In addition, specific species from these subclasses were discovered to be correlated with embryo development outcomes during ART. Notably, the composition of the fatty acyl chains appeared to play a crucial role in these associations. Furthermore, thirteen plasma lipid variables were identified, represented by Phosphatidylcholine 18:014:0 and PE P-18:020:1, which correlated with successful blastocyst formation (BF).

Discussion

The present study demonstrated that FF has a distinctive lipid composition, setting it apart from plasma; and the association observed with embryonic development underscored an important role of lipid composition in the healthy development of oocytes.

Effect of intrafollicular administration of PGE2 or PGF2α in early estrus on ovulation, hemorrhagic anovulatory follicles formation, progesterone secretion and pregnancy outcome in the mare

This experiment was performed to evaluate whether intrafollicular treatment of PGE2 or PGF2α administered in early estrus would induce normal ovulation, progesterone production (Experiment 1) and pregnancy (Experiment 2). In Experiment 1, mares in estrus after 2 days of endometrial edema were injected in all largest dominant follicles (28-35 mm in diameter) with 0.5 mL of sterile water containing 500 μg PGE2 (n = 6), 125 μg PGF2α (n = 6) or placebo (n = 7) (Hour 0). Ultrasound examinations were performed daily, until ovulation or anovulation was detected, and daily blood samples were taken for 8 days. In Experiment 2, mares with a dominant follicle ≥35 mm after at least three days of slight-to-moderate endometrial edema, were injected with 500 μg PGE2 diluted in 0.5 mL of sterile water for injection in the follicle (PGE2 group; n = 9 mares and 11 dominant follicles). No puncture was performed in the control group (n = 9 mares and 11 dominant follicles). Mares from both groups were inseminated. In Experiment 1, all mares (6/6) in the PGE2 group ovulated within 24 h of treatment. The mean interval from intrafollicular injection to ovulation was shorter (P < 0.001) in PGE2 mares (24 ± 0 h) than in control mares (77 ± 9 h). Mares from the PGF2α group developed hemorrhagic anovulatory follicles (HAF) more often (7/7) than control mares (2/7); P < 0.05). The progesterone concentration in mares from the PGF2α group was lower (P < 0.004) than control mares in the early post-ovulatory period. The first significant increase in post-ovulatory progesterone concentration occurred earlier (P < 0.05) in mares from the control group than in mares from the PGF2α and PGE2 groups. In Experiment 2, more mares from the control group (7/9, 78 %) became pregnant than from the PGE2 group (2/9, 22 %) (P = 0.015). In conclusion, PGE2 alone induced follicle collapse in all treated mares within 24 h of administrations, while PGF2α blocked ovulation and induced formation of HAFs. However, the post-ovulatory rise in progesterone production was delayed and the fertility reduced in mares with ovulation induced by PGE2 compared to control mares.

Ibuprofen delays ovulation by several hours: prospective controlled study in natural cycles with HCG-triggered ovulation

RESEARCH QUESTION

Does ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), delay ovulation?

DESIGN

Two-stage, proof-of-concept, controlled study, assessing the percentage of non-ovulated follicles 42 h after HCG injection in patients taking ibuprofen. The intervention group consisted of women undergoing natural cycle IVF treatment taking ibuprofen 3 × 400 mg per day. The control group consisted of women undergoing timed sexual intercourse or intrauterine insemination. The proportion of patients with non-ovulated follicles in the ibuprofen group was first compared against a reference of 50% using a one-sample binomial test, and second against the proportion observed in the control group using an adjusted logistic regression.

RESULTS

A total of 26 women were recruited in the ibuprofen intervention group. Twenty-five patients were recruited in the control group. The proportion of patients with delayed ovulation observed (22/26 [84.6%]; 95% CI 65.1% to 95.6%) was significantly higher than the reference of 50% (P < 0.001). In the control group, the proportion of patients with delayed ovulation was 20.0% ([5/25], 95% CI 6.8% to 40.7%). Compared with the ibuprofen group, a significantly increased probability of a delayed ovulation was found in the ibuprofen intervention group (adjusted OR 22.72, 95% CI 5.77 to 115; P < 0.001). Of the 22 women with delayed ovulation, oocytes were retrieved in 20 women (90.9%) and all oocytes were mature (metaphase II).

CONCLUSIONS

Women trying to conceive should avoid non-selective NSAIDs around the time of ovulation. Ibuprofen or other NSAID can be used to delay ovulation for several hours in assisted reproductive technology and other infertility treatments if required.

Hypoxia, NSAIDs, and autism: A biocultural analysis of stressors in gametogenesis

Cultural and generational trends have increasingly favored "anti-inflammatory" action, innovating a new class of analgesic, non-steroidal anti-inflammatory drugs (NSAIDs) in the 20th century. The modern human body has been molded over evolutionary time and while acknowledging inflammation can be pathologically entwined, it also serves an important role in healthy folliculogenesis and ovulation, shaping cues that drive needed vascular change. This review argues that because of anti-inflammatory action, the cultural invention of NSAIDs represents a particular stressor on female reproductive-age bodies, interacting with natural, underlying variation and placing limits on healthy growth and development in the follicles, creating potential autism risk through hypoxia and mutagenic or epigenetic effects. Since testes are analogs to ovaries, the biological grounding extends naturally to spermatogenesis. This review suggests the introduction of over-the-counter NSAIDs in the 1980s failed to recognize the unique functioning of reproductive-age bodies, challenging the cyclical inflammation needed for healthy gamete development. NSAIDs are framed as one (notable) stressor in an anti-inflammatory era focused on taming the risks of inflammation in modern human life.

Clinical outcomes of frozen-thawed embryo transfer in natural cycles with luteinized unruptured follicles

OBJECTIVE

To assess the effect of luteinized unruptured follicles (LUF) on frozen-thawed embryo transfer cycles performed in natural cycles (FET-NC).

METHODS

Retrospective cohort study, held in a university hospital with 3415 cycles for frozen-thawed embryo transfer, performed between June 2019 and September 2022. Using propensity score matching, 242 patients with a diagnosis of LUF (LUF group) were matched with 484 ovulated patients (ovulation group). Stratified by the type of embryo transferred, the LUF group included 168 blastocyst transfer patients (blastocyst group) and 74 cleavage-stage embryo transfer patients (cleavage-embryo group). The ovulation group included 324 patients with blastocyst transfer (blastocyst group) and 160 patients with transferred cleavage-stage embryos. Clinical pregnancy rate was retrospectively analyzed between the LUF and ovulation groups, as well as between each subgroup.

RESULTS

After using propensity score matching, the general characteristics of the LUF and ovulation groups were similar. The implantation and clinical pregnancy rates in the LUF group were not significantly different from those in the ovulation group (44.98 % vs. 45.29 %, p = 0.93; 53.72 % vs. 52.48 %, p = 0.75). The implantation and pregnancy rates of transferred cleavage-stage embryos in the LUF group were also not significantly different from those in the ovulation group (32.39 % vs. 36.40 %, p = 0.42; 47.30 % vs. 47.50 %, p = 0.98). The implantation and pregnancy rates of transferred blastocysts in the LUF group were also not significantly different from those in the ovulation group (53.11 % vs. 52.03 %, p = 0.82; 56.55 % vs. 54.94 %, p = 0.73). There was also no significant difference in the miscarriage rate between the groups.

CONCLUSION

In the natural cycle, LUF does not affect the clinical pregnancy outcomes of FET. If adequate luteal support is given, the clinical pregnancy outcomes were similar between the LUF group and ovulation group.

Validation of urinary reproductive hormone measurements using a novel smartphone connected reader

Home use tests to monitor hormone trends during the menstrual cycle have been available over-the-counter for a long time. However, these tests often depend upon manual readouts and hence may lead to false analysis. Furthermore, a lot of these tests are also not quantitative. The aim of this study was to evaluate the accuracy of the quantitative home-based fertility monitor, Inito Fertility Monitor (IFM) and to use it to identify novel hormone trends in natural menstrual cycles. There were two aspects to our analysis: (i) Evaluating the efficacy of Inito Fertility Monitor in the measurement of urinary Estrone-3-glucuronide (E3G), Pregnanediol glucuronide (PdG) and Luteinizing hormone (LH), and (ii) A retrospective study of patients' hormone profiles using IFM. To evaluate the efficacy, the recovery percentage of the three hormones from IFM was evaluated using standard spiked solutions, the accuracy of measurement was calculated and the correlation between reproducible values from IFM and ELISA was established. During the validation of IFM, novel hormone trends were also observed. In order to reinforce the observations, a second group of 52 women was recruited. Assessment of the accuracy of IFM and evaluation of the volunteer urine samples was performed in a laboratory. Home assessment of hormone analysis was carried out using IFM. For the validation study, 100 women aged 21-45 years with cycle lengths ranging from 21 to 42 days were recruited. The participants had no previously diagnosed infertility conditions and their cycle lengths did not vary for more than 3 days from the expected cycle length. Daily first morning urine samples were collected from these 100 women. For the second group, 52 women were selected meeting the same criteria set for the validation study and IFM was provided to these women for testing at home. Coefficient of variation and recovery percentage of IFM with respect to laboratory based ELISA. Percentage occurrence of novel hormone trends and AUC analysis of a novel criteria identified for confirming ovulation. We observed that with all three hormones, IFM had an accurate recovery percentage. We found that the assay has an average CV of 5.05% in PdG measurement, 4.95% in E3G measurement and 5.57% in LH measurement. Furthermore, in predicting the concentration of E3G, PdG and LH in urine samples, we show that IFM has a high correlation with ELISA. In this study, we could also reproduce hormones trends across the menstrual cycle that have been observed by previous studies. We also identified a novel criterion for earlier confirmation of ovulation which could accurately distinguish ovulatory from anovulatory cycles with 100% specificity and had an area under the ROC curve of 0.98. In addition, we identified a new hormone trend which could be observed in 94.5% of the ovulatory cycles. The Inito Fertility Monitor is an effective tool for calculating the urinary concentrations of E3G, PdG and LH and can also be used to provide accurate fertility scores and confirm ovulation. We show that certain hormone trends associated with urinary E3G, PdG and LH could be accurately captured using IFM. In addition, we report a novel criterion for earlier confirmation of ovulation compared to existing criteria. Finally, we present a novel hormone pattern associated with most of the menstrual cycles by examining hormone profiles from the volunteers recruited for the clinical trial.Trial registration: The trial is registered at the current controlled trials ISRCTN registry #ISRCTN15534557.

ABCC4 is a PGE2 efflux transporter in the ovarian follicle: A mediator of ovulation and a potential non-hormonal contraceptive target

The role of prostaglandins (PGs) in the ovulatory process is known. However, the role of the ATP binding cassette subfamily C member 4 (ABCC4), transmembrane PG carrier protein, in ovulation remains unknown. We report herein that ABCC4 expression is significantly upregulated in preovulatory human granulosa cells (GCs). We found that PGE2 efflux in cultured human GCs is mediated by ABCC4 thus regulating its extracellular concentration. The ABCC4 inhibitor probenecid demonstrated effective blocking of ovulation and affects key ovulatory genes in female mice in vivo. We postulate that the reduction in PGE2 efflux caused by the inhibition of ABCC4 activity in GCs decreases the extracellular concentration of PGE2 and its ovulatory effect. Treatment of female mice with low dose of probenecid as well as with the PTGS inhibitor indomethacin or Meloxicam synergistically blocks ovulation. These results support the hypothesis that ABCC4 has an important role in ovulation and might be a potential target for non-hormonal contraception, especially in combination with PGE2 synthesis inhibitors. These findings may fill the gap in understanding the role of ABCC4 in PGE2 signaling, enhance the understanding of ovulatory disorders, and facilitate the treatment and control of fertility.

Granulosa cell proliferation is inhibited by PGE2 in the primate ovulatory follicle

Prostaglandin E2 (PGE2) is a key paracrine mediator of ovulation. Few specific PGE2-regulated gene products have been identified, so we hypothesized that PGE2 may regulate the expression and/or activity of a network of proteins to promote ovulation. To test this concept, Ingenuity Pathway Analysis (IPA) was used to predict PGE2-regulated functionalities in the primate ovulatory follicle. Cynomolgus macaques underwent ovarian stimulation. Follicular granulosa cells were obtained before (0 h) or 36 h after an ovulatory dose of human chorionic gonadotropin (hCG), with ovulation anticipated 37–40 h after hCG. Granulosa cells were obtained from additional monkeys 36 h after treatment with hCG and the PTGS2 inhibitor celecoxib, which significantly reduced hCG-stimulated follicular prostaglandin synthesis. Granulosa cell RNA expression was determined by microarray and analyzed using IPA. No granulosa cell mRNAs were identified as being significantly up-regulated or down-regulated by hCG + celecoxib compared with hCG only. However, IPA predicted that prostaglandin depletion significantly regulated several functional pathways. Cell cycle/cell proliferation was selected for further study because decreased granulosa cell proliferation is known to be necessary for ovulation and formation of a fully-functional corpus luteum. Prospective in vivo and in vitro experiments confirmed the prediction that hCG-stimulated cessation of granulosa cell proliferation is mediated via PGE2. Our studies indicate that PGE2 provides critical regulation of granulosa cell proliferation through mechanisms that do not involve significant regulation of mRNA levels of key cell cycle regulators. Pathway analysis correctly predicted that PGE2 serves as a paracrine mediator of this important transition in ovarian structure and function.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

Detection of ovulation, a review of currently available methods

The ability to identify the precise time of ovulation is important for women who want to plan conception or practice contraception. Here, we review the current literature on various methods for detecting ovulation including a review of point‐of‐care device technology. We incorporate an examination of methods to detect ovulation that have been developed and practiced for decades and analyze the indications and limitations of each—transvaginal ultrasonography, urinary luteinizing hormone detection, serum progesterone and urinary pregnanediol 3‐glucuronide detection, urinary follicular stimulating hormone detection, basal body temperature monitoring, and cervical mucus and salivary ferning analysis. Some point‐of‐care ovulation detection devices have been developed and commercialized based on these methods, however previous research was limited by small sample size and an inconsistent standard reference to true ovulation.

Low-Dose Aspirin and Sporadic Anovulation in the EAGeR Randomized Trial

CONTEXT

Among women with a single, recent pregnancy loss, daily preconception low-dose aspirin (LDA) increased the live birth rate with no effect on pregnancy loss. Ovulation is a potential mechanism underlying this effect.

OBJECTIVE

We estimated the effect of LDA on the per-cycle risk of anovulation among eumenorrheic women.

DESIGN

Multicenter, randomized, double-blind, placebo-controlled trial of daily LDA on reproductive outcomes. Preconception follow-up lasted 1 to 6 menstrual cycles (ClinicalTrials.gov, NCT00467363).

SETTING

Four US medical centers during 2007 to 2011.

PATIENTS OR OTHER PARTICIPANTS

Healthy women (n = 1214), age 18 to 40, were attempting pregnancy, had regular menstrual cycles (21 to 42 days), and had a history of 1 to 2 documented pregnancy losses, ≤2 live births, and no infertility. All participants completed at least 1 menstrual cycle of follow-up; none withdrew due to adverse events.

INTERVENTION

Aspirin (81 mg) daily for 1 to 6 menstrual cycles.

MAIN OUTCOME MEASURE

Per-cycle risk of anovulation, defined as the absence of both a positive spot-urine pregnancy test and a luteinizing hormone (LH) peak (2.5-fold increase in daily urinary LH). Hypothesis formulation preceded data collection.

RESULTS

Among 4340 cycles, LDA was not associated with anovulation (LDA: 13.4%, placebo: 11.1%; risk ratio = 1.16, 95% confidence interval, 0.88 to 1.52). Results were similar among women with a single, recent loss.

CONCLUSIONS

Daily LDA had no effect on anovulation among women with a history of 1 to 2 pregnancy losses. LDA may affect fertility via other pathways, and these warrant further study.

A single dose of allopregnanolone affects the ovarian morphology and steroidogenesis

Allopregnanolone, a progesterone metabolite, is one of the best characterized neurosteroids. In a dose that mimics serum levels during stress, allopregnanolone inhibits sexual receptivity and ovulation and induces a decrease in luteinizing hormone levels. The aim of this work was to examine the effect of an intracerebroventricular administration of allopregnanolone on ovarian morphophysiology, serum and tissue levels of progesterone and estrogen, and enzymatic activity of 3β-hydroxysteroid dehydrogenase, 20α-hydroxysteroid dehydrogenase and 3α-hydroxysteroid oxido-reductase in the ovary and in the medial basal hypothalamus on the morning of estrus. Ovarian morphology was analyzed under light microscopy. The hormone assays were performed by radioimmunoassay. The enzymatic activities were measured by spectrophotometric analysis. The morphometric analysis revealed that, in allopregnanolone-treated animals, the number of secondary and Graafian follicles was decreased while that of atretic follicles and cysts was significantly increased. Some cysts showed luteinized unruptured follicles. There were no differences in the number of tertiary follicles or corpora lutea in comparison with the corresponding control groups. In allopregnanolone-treated animals, progesterone serum levels were increased, while ovarian progesterone levels were decreased. Moreover, 3β-HSD and 3α-HSOR enzymatic activities were increased in the medial basal hypothalamus while ovarian levels were decreased. The enzyme 20α-hydroxysteroid dehydrogenase showed the opposite profile. The results of this study showed that allopregnanolone interferes on ovarian steroidogenesis and ovarian morphophysiology in rats, providing a clear evidence for the role of this neurosteroid in the control of reproductive function under stress situations.

Granulocyte colony-stimulating factor as a potential inducer of ovulation in infertile women with luteinized unruptured follicle syndrome

Luteinized unruptured follicle (LUF) syndrome is one of the intractable ovulation disorders that are commonly observed during cycles of treatment with ovulation inducers, for which no effective therapy other than assisted reproductive technology is available. Here, we investigated whether granulocyte colony-stimulating factor (G-CSF) could prevent the onset of LUF syndrome. We analyzed the effects of G-CSF in 68 infertile women with LUF syndrome who received ovulation induction (clomiphene + human chorionic gonadotropin [hCG] therapy or follicle-stimulating hormone + hCG therapy). G-CSF (lenograstim, 100 μg) was administered subcutaneously. Onsets of LUF syndrome were compared between the cycle during which G-CSF was given in combination with the ovulation inducer (ie, the G-CSF treatment cycle) and the subsequent cycle during which only the ovulation inducer was given (ie, the G-CSF nontreatment control cycle). The results showed that LUF syndrome recurred in only 3 cycles during the G-CSF treatment cycle (4.4% [3/68 cycles]), whereas LUF syndrome recurred in 13 cycles during the subsequent G-CSF nontreatment control cycle (19.1% [13/68 cycles]). The additional use of G-CSF significantly prevented the onset of LUF syndrome during ovulation induction (P = 0.013, McNemar test). No serious adverse reactions because of the administration of G-CSF were observed. In conclusion, our findings indicate that G-CSF may become a useful therapy for LUF syndrome.

The mare as a model for luteinized unruptured follicle syndrome: intrafollicular endocrine milieu

Luteinized unruptured follicle (LUF) syndrome is a recurrent anovulatory dysfunction that affects up to 23% of women with normal menstrual cycles and up to 73% with endometriosis. Mechanisms underlying the development of LUF syndrome in mares were studied to provide a potential model for human anovulation. The effect of extended increase in circulating LH achieved by administration of recombinant equine LH (reLH) or a short surge of LH and decrease in progesterone induced by prostaglandin F2α (PGF2α) on LUF formation (Experiment 1), identification of an optimal dose of COX-2 inhibitor (flunixin meglumine, FM; to block the effect of prostaglandins) for inducing LUFs (Experiment 2), and evaluation of intrafollicular endocrine milieu in LUFs (Experiment 3) were investigated. In Experiment 1, mares were treated with reLH from Day 7 to Day 15 (Day 0=ovulation), PGF2α on Day 7, or in combination. In Experiment 2, FM at doses of 2.0 or 3.0 mg/kg every 12 h and human chorionic gonadotropin (hCG) (1500 IU) were administered after a follicle ≥32 mm was detected. In Experiment 3, FM at a dose of 2.0 mg/kg every 12 h plus hCG was used to induce LUFs and investigate the intrafollicular endocrine milieu. No LUFs were induced by reLH or PGF2α treatment; however, LUFs were induced in 100% of mares using FM. Intrafollicular PGF2α metabolite, PGF2α, and PGE2were lower and the ratio of PGE2:PGF2α was higher in the induced LUF group. Higher levels of intrafollicular E2 and total primary sex steroids were observed in the induced LUF group along with a tendency for higher levels of GH, cortisol, and T; however, LH, PRL, VEGF-A, and NO did not differ between groups. In conclusion, this study reveals part of the intrafollicular endocrine milieu and the association of prostaglandins in LUF formation, and indicates that the mare might be an appropriate model for studying the poorly understood LUF syndrome.

Novel contraceptive targets to inhibit ovulation: the prostaglandin E2 pathway

BACKGROUND

Prostaglandin E2 (PGE2) is an essential intrafollicular regulator of ovulation. In contrast with the one-gene, one-protein concept for synthesis of peptide signaling molecules, production and metabolism of bioactive PGE2 requires controlled expression of many proteins, correct subcellular localization of enzymes, coordinated PGE2 synthesis and metabolism, and prostaglandin transport in and out of cells to facilitate PGE2 action and degradation. Elevated intrafollicular PGE2 is required for successful ovulation, so disruption of PGE2 synthesis, metabolism or transport may yield effective contraceptive strategies.

METHODS

This review summarizes case reports and studies on ovulation inhibition in women and macaques treated with cyclooxygenase inhibitors published from 1987 to 2014. These findings are discussed in the context of studies describing levels of mRNA, protein, and activity of prostaglandin synthesis and metabolic enzymes as well as prostaglandin transporters in ovarian cells.

RESULTS

The ovulatory surge of LH regulates the expression of each component of the PGE2 synthesis-metabolism-transport pathway within the ovulatory follicle. Data from primary ovarian cells and cancer cell lines suggest that enzymes and transporters can cooperate to optimize bioactive PGE2 levels. Elevated intrafollicular PGE2 mediates key ovulatory events including cumulus expansion, follicle rupture and oocyte release. Inhibitors of the prostaglandin-endoperoxide synthase 2 (PTGS2) enzyme (also known as cyclooxygenase-2 or COX2) reduce ovulation rates in women. Studies in macaques show that PTGS2 inhibitors can reduce the rates of cumulus expansion, oocyte release, follicle rupture, oocyte nuclear maturation and fertilization. A PTGS2 inhibitor reduced pregnancy rates in breeding macaques when administered to simulate emergency contraception. However, PTGS2 inhibition did not prevent pregnancy in monkeys when administered to simulate monthly contraceptive use.

CONCLUSION

PTGS2 inhibitors alone may be suitable for use as emergency contraceptives. However, drugs of this class are unlikely to be effective as monthly contraceptives. Inhibitors of additional PGE2 synthesis enzymes or modulation of PGE2 metabolism or transport also hold potential for reducing follicular PGE2 and preventing ovulation. Approaches which target multiple components of the PGE2 synthesis-metabolism-transport pathway may be required to effectively block ovulation and lead to the development of novel contraceptive options for women. Therapies which target PGE2 may also impact disorders of the uterus and could also have benefits for women's health in addition to contraception.

Production of Sry knockout mouse using TALEN via oocyte injection

Recently developed transcription activator-like effector nuclease (TALEN) technology has enabled the creation of knockout mice, even for genes on the Y chromosome. In this study, we generated a knockout mouse for Sry, a sex-determining gene on the Y chromosome, using microinjection of TALEN RNA into pronuclear stage oocytes. As expected, the knockout mouse had female external and internal genitalia, a female level of blood testosterone and a female sexually dimorphic nucleus in the brain. The knockout mouse exhibited an estrous cycle and performed copulatory behavior as females, although it was infertile or had reduced fertility. A histological analysis showed that the ovary of the knockout mouse displayed a reduced number of oocytes and luteinized unruptured follicles, implying that a reduced number of ovulated oocytes is a possible reason for infertility and/or reduced fertility in the KO mouse.

Developmental programming: postnatal estradiol amplifies ovarian follicular defects induced by fetal exposure to excess testosterone and dihydrotestosterone in sheep

Excess of prenatal testosterone (T) induces reproductive defects including follicular persistence. Comparative studies with T and dihydrotestosterone (DHT) have suggested that follicular persistence is programmed via estrogenic actions of T. This study addresses the androgenic and estrogenic contributions in programming follicular persistence. Because humans are exposed to estrogenic environmental steroids from various sources throughout their life span and postnatal insults may also induce organizational and/or activational changes, we tested whether continuous postnatal exposure to estradiol (E) will amplify effects of prenatal steroids on ovarian function. Pregnant sheep were treated with T, DHT, E, or ED (E and DHT) from days 30 to 90 of gestation. Postnatally, a subset of the vehicle (C), T, and DHT females received an E implant. Transrectal ultrasonography was performed in the first breeding season during a synchronized cycle to monitor ovarian follicular dynamics. As expected, number of ≥8 mm follicles was higher in the T versus C group. Postnatal E reduced the number of 4 to 8 mm follicles in the DHT group. Percentage of females bearing luteinized follicles and the number of luteinized follicles differed among prenatal groups. Postnatal E increased the incidence of subluteal cycles in the prenatal T-treated females. Findings from this study confirm previous findings of divergences in programming effects of prenatal androgens and estrogens. They also indicate that some aspects of follicular dynamics are subject to postnatal modulation as well as support the existence of an extended organizational period or the need for a second insult to uncover the previously programmed event.

The COX-2 inhibitor meloxicam prevents pregnancy when administered as an emergency contraceptive to nonhuman primates

OBJECTIVE

Cyclooxygenase-2 (COX-2) inhibitors reduce prostaglandin synthesis and disrupt essential reproductive processes. Ultrasound studies in women demonstrated that oral COX-2 inhibitors can delay or prevent follicle collapse associated with ovulation. The goal of this study was to determine if oral administration of a COX-2 inhibitor can inhibit reproductive function with sufficient efficacy to prevent pregnancy in primates.

STUDY DESIGN

The COX-2 inhibitor meloxicam (or vehicle) was administered orally to proven fertile female cynomolgus macaques using one emergency contraceptive model and three monthly contraceptive models. In the emergency contraceptive model, females were bred with a proven fertile male once 2±1 days before ovulation, returned to the females' home cage, and then received 5 days of meloxicam treatment. In the monthly contraceptive models, females were co-caged for breeding with a proven fertile male for a total of 5 days beginning 2±1 days before ovulation. Animals received meloxicam treatment (1) cycle days 5-22, or (2) every day, or (3) each day of the 5-day breeding period. Female were then assessed for pregnancy.

RESULTS

The pregnancy rate with meloxicam administration using the emergency contraception model was 6.5%, significantly lower than the pregnancy rate of 33.3% when vehicle without meloxicam was administered. Pregnancy rates with the three monthly contraceptive models (75%-100%) were not consistent with preventing pregnancy.

CONCLUSIONS

Oral COX-2 inhibitor administration can prevent pregnancy after a single instance of breeding in primates. While meloxicam may be ineffective for regular contraception, pharmacological inhibition of COX-2 may be an effective method of emergency contraception for women.

IMPLICATIONS

COX-2 inhibitors can interfere with ovulation, but the contraceptive efficacy of drugs of this class has not been directly tested. This study, conducted in nonhuman primates, is the first to suggest that a COX-2 inhibitor may be effective as an emergency contraceptive.

Delay of Ovulation by Meloxicam in Healthy Cycling Volunteers: A Placebo-Controlled, Double-blind, Crossover Study

This study aimed to assess the effect of meloxicam on female ovulation. Twenty consented fertile females were monitored for 4 menstrual cycles: a baseline cycle, 2 treatment cycles, and a washout cycle between treatment cycles. In the first cycle visit, transvaginal ultrasound was performed, a blood sample for progesterone and meloxicam analysis was withdrawn, and volunteers were given a luteinizing hormone (LH) urine test kit and meloxicam or placebo. Volunteers started the treatment on the following day and asked to return the day the LH kit was positive to detect the dominant follicle. At subsequent visits, transvaginal ultrasound and progesterone and meloxicam levels were investigated. Compared to placebo, a 5-day delay in follicle rupture, a 55.7% increase in the mean maximum follicle diameter, and 33.5% decrease of plasma progesterone level were observed in the meloxicam-treated group. Such demonstrated meloxicam effects were reversed in participants who were randomized to meloxicam first and then placebo. Only minor side effects were reported by volunteers during the course of treatment. It is concluded that meloxicam resulted in a reversible delay of ovulation, an increase in follicular diameter, and a decrease in plasma progesterone level.

Inhibition of prostaglandin biosynthesis during postluteolysis and effects on CL regression, prolactin, and ovulation in heifers

The beginning of postluteolysis (progesterone, <1 ng mL(-1)) in heifers was targeted by using 8 h after ultrasonic detection of a 25% decrease in CL area (cm2) and was designated Hour 0. Flunixin meglumine (FM; n=10) to inhibit PGF2α secretion or vehicle (n=9) were given intramuscularly at Hours 0, 4, 8, 16, 24, 32, and 40. The dose of FM was 2.5 mg/kg at each treatment. Blood sampling and measurement of the CL and dominant follicle were done every 8 h beginning 14 days postovulation in each group. Blood samples for detection of pulses of PRL and pulses of a metabolite of PGF2α (PGFM) were obtained every hour for 24 h beginning at Hour 0. Pulse concentrations of both PGFM and PRL were lower in the FM group than in the vehicle group. Concentration of PRL was greatest at the peak of a PGFM pulse. Neither CL area (cm2) nor progesterone concentration differed between groups during Hours 0 to 48 (postluteolysis). Ovulation occurred in nine of nine heifers in the vehicle group and in three of 10 heifers in the FM group. The anovulatory follicles in the FM group grew to 36.2±2.9 mm, and the wall became thickened from apparent luteinization. The hypothesis that PGF2α was involved in the continued P4 decrease and structural CL regression during postluteolysis was not supported. However, the hypotheses that pulses of PGFM and PRL were temporally related and that systemic FM treatment induced an anovulatory follicle were supported.

Contraception by induction of luteinized unruptured follicles with short-acting low molecular weight FSH receptor agonists in female animal models

During recent decades minor innovative drugs have been developed for the female contraceptive market and they all contain steroidal progestagens (and estrogens) that act centrally and have side effects that can be attributed to this central action. In this study, we present an innovative tissue-specific approach for female contraception by low molecular weight (LMW) FSH receptor (FSHR) agonists, which interact with the FSHR that is dominantly expressed in the granulosa cells. The oral administration of LMW FSHR agonists with a short circulation time, induced formation of luteinized unruptured follicles (LUFs) from the Graafian follicles, thereby preventing the release of the oocyte. The short-acting LMW FSHR compounds were fully agonistic to FSHR (EC50=4–5 nM). In an isolated mouse follicle culture, a short incubation period (2 h) resulted in inhibition of follicular rupture, where continuous incubation induced follicle growth. Pharmacokinetics after oral administration showed a surge-like exposure in rats and monkeys. Oral administration of short-acting LMW FSHR agonists inhibited ovulation at 10 mg/kg in rats and guinea pigs by generating LUFs without affecting cyclicity. Also, inhibition of follicular rupture was shown to be reversible within one cycle. Finally, LUFs were induced without affecting the hormonal cyclicity in cynomolgus monkeys, a mono-ovulatory species. In healthy women LUF formation occurs naturally, with a LUF acting as corpus luteum that produces enough progesterone to ensure normal menstrual cyclicity. Together with the presented data this indicates that the innovative approach with short-acting LMW FSHR agonists could lead to oral contraception for females at the ovarian level.

Ultrasound characteristics of experimentally induced luteinized unruptured follicles (LUF) and naturally occurring hemorrhagic anovulatory follicles (HAF) in the mare

The development of hemorrhagic anovulatory follicles (HAF) involves luteinization and hemorrhage of the follicle. This is observed on ultrasound as an increase in the echogenicity of the granulosa layer and formation of echoic particles in the antrum. The inhibition of prostaglandin synthesis with flunixin meglumine (FM) during the periovulatory period induces ovulatory failure with development of luteinized unruptured follicles (LUF). These two types of anovulatory follicles appear to share similar ultrasound features but they have not been compared critically. The following endpoints: follicle diameter, follicular contents score, interval from hCG administration to beginning of follicular hemorrhage, interval from hemorrhage to organization of follicular contents, and cycle length were studied and compared in mares with HAF (n = 11) and LUF (n = 13). The objective of this study was to elucidate whether these two unruptured follicles have a consistent clinical pattern of development and therefore can be considered as part of the same anovulatory syndrome. None of the endpoints analyzed differed significantly between HAF and LUF. However, there was a greater individual variation in HAF as compared with LUF in regards to interval from hCG to hemorrhage, follicular diameter at the administration of hCG, and beginning of hemorrhage. In conclusion, HAF share a similar cascade of ultrasound characteristics with the experimentally induced LUF. This finding may provide new insights in elucidating the pathogenesis of HAF.

The effect of treatment with flunixin meglumine at different times relative to hCG administration on ovulation failure and luteal function in mares

Flunixin meglumine (FM), a prostaglandin synthetase inhibitor, causes ovulatory failure in the mare. However, the effect of the FM treatment relative to the time of hCG administration on the ovulation failure has not been determined nor has its effect on the luteal function of treated mares. Estrous mares with a follicle ≥32 mm (range of 32-38 mm) were treated with 1.7 mg/kg b.w. of FM iv at zero, 12, 24 and 36 h (n=6), at 24 and 36 h (n=6), at 28 and 36 h (n=6), at 24h (n=6) or at 30 h (n=6) after treatment with 1500 IU hCG. One group received no FM (control, n=6). Progesterone concentrations were determined using RIA. Mares treated with FM 0-36 h and 24-36 h had higher (P<0.05) incidence of ovulatory failure (83 and 80%, respectively) than mares treated twice at 28 and 36 h, or once at 24 or at 30 h after hCG (16.7, 0 and 0%, respectively). The anovulatory follicles of FM treated mares luteinized and produced progesterone (>2 ng/ml). The progesterone concentration was lower in mares treated with FM at zero to 36 h and at 24-36 h after hCG than in the other groups. In conclusion, the FM administration was effective in blocking ovulation only when the treatment began ≤24 h after hCG and was continued every 12 h until ≥36 h. In addition, the FM-induced anovulatory follicles underwent luteinization of follicular cells with active production of progesterone.

[Comparison between two analgesic protocols on IVF success rates]

OBJECTIVES

Analgesic protocols administered before a follicular puncture under local anesthesia are well tolerated when using NSAIDs, but we still do not know their possible impacts on in vitro fertilization (IVF) outcomes.

MATERIAL AND METHODS

A retrospective monocentric study using two consecutive temporal cohorts of patients was conducted to compare two analgesic protocols: paracetamol/alprazolam (P/A), then nefopam/ketoprofen (N/K).

RESULTS

We demonstrated that biochemical pregnancy rate and the others outcomes of IVF are not significantly influenced by the type of analgesic protocol used.

CONCLUSION

The protocol N/K enhances patient comfort without jeopardizing the IVF success rates.

Migraine therapy during pregnancy and lactation

IMPORTANCE OF THE FIELD

Migraine affects about 25% of women during childbearing years but few data are available about the risks connected with most antimigraine drugs during pregnancy.

AREAS COVERED IN THIS REVIEW

In this report, we review the available data, mainly obtained from published studies, toxicology databases and clinical guidelines, on migraine treatment during pregnancy and lactation.

WHAT THE READER WILL GAIN

The following drugs should be preferred for the treatment of acute migraine attacks in pregnant women: paracetamol, NSAIDs and sumatriptan. Migraine prophylaxis should be undertaken when patients experience at least three prolonged severe attacks a month that are particularly incapacitating or unresponsive to symptomatic therapy and likely to result in complications. Non-pharmacologic approaches should be preferred, but if they are not effective, preventive treatment should include low doses of β-blockers and amitriptyline.

TAKE HOME MESSAGE

Migraine treatment is often necessary because maternal and fetal risks related to acute attacks may be more harmful than the therapy itself, especially if they are frequent, severe and associated with nausea, anorexia, vomiting, hypotension or dehydration. If non-pharmacologic treatments do not alleviate migraine symptoms, only few drugs can be used during pregnancy and lactation.

Maturation and fertilization of nonhuman primate oocytes are compromised by oral administration of a cyclooxygenase-2 inhibitor

OBJECTIVE

To determine if oral administration of a cyclooxygenase-2 (COX2) inhibitor affects oocyte nuclear maturation and fertilization in nonhuman primates.

DESIGN

Laboratory research study.

SETTING

Medical school.

ANIMAL(S)

Adult female cynomolgus monkeys (Macaca fascicularis).

INTERVENTION(S)

Monkeys received gonadotropins to stimulate multiple follicular development. An ovulatory dose of hCG was administered either alone or with oral celecoxib, a COX2 inhibitor. Oocytes were retrieved 36 hours later and exposed to sperm in vitro.

MAIN OUTCOME MEASURE(S)

Oocytes were assessed for nuclear status at retrieval, resumption of meiosis in vitro, and success of in vitro fertilization.

RESULT(S)

Treatment with hCG alone yielded oocytes that were primarily (72.9%) at the meiosis II (MII) stage of nuclear maturation; few oocytes were obtained at the germinal vesicle and germinal vesicle breakdown stages. Treatment with hCG and celecoxib yielded fewer mature (MII) oocytes (35.6%) and more oocytes at less mature stages compared with oocytes from monkeys treated with hCG alone. The majority (68.3 ± 15.9%) of MII oocytes from monkeys treated with hCG alone fertilized in vitro, compared with only 11.0 ± 5.9% of MII oocytes from monkeys treated with hCG and celecoxib.

CONCLUSION(S)

Oral administration of a COX2 inhibitor reduced the rate of oocyte nuclear maturation and the success of in vitro fertilization. Drugs of this class may block multiple essential steps in female reproduction and be effective contraceptives for women.

The 9-cis retinoic acid signaling pathway and its regulation of prostaglandin-endoperoxide synthase 2 during in vitro maturation of pig cumulus cell-oocyte complexes and effects on parthenogenetic embryo production

The addition of 9-cis retinoic acid to the oocyte maturation culture medium has a beneficial effect on in vitro fertilized embryos. However, the mechanism of this activity is not known. Therefore, this study was done to elucidate the effect of 9-cis retinoic acid on parthenogenetic embryo production and its signaling pathway and molecular function during in vitro maturation of porcine cumulus cell-oocyte complexes (COCs). Concentrations of 0, 5, 50, and 500 nM 9-cis retinoic acid were added to the in vitro maturation medium, and the embryos were assessed after parthenogenetic activation. Cumulus cells and oocytes from the in vitro matured COCs were separated and subjected to RT-PCR and real-time RT-PCR for detecting retinoic acid receptors and measuring expression of prostaglandin-endoperoxide synthase1 and 2. The addition of 5 nM 9-cis retinoic acid to the maturation medium was beneficial for parthenogenetic embryo production. The effect of 9-cis retinoic acid was exerted directly through the oocytes via the retinoic acid receptor alpha and retinoid X receptor gamma signaling pathways and indirectly through the cumulus cells by the retinoic acid receptor beta and gamma and retinoid X receptor alpha and beta signaling pathways. The addition of 5 nM 9-cis retinoic acid-stimulated cumulus cells reaches full expansion by suppressing their excessive expression of prostaglandin-endoperoxide synthase 2. This study shows that 9-cis retinoic acid can exert its beneficial effect on parthenogenetic embryo production in pigs by multidimensional pathways affecting oocyte maturation.

A nonhormonal model for emergency contraception: prostaglandin synthesis inhibitor effects on luteal function and lifespan, a pilot study

OBJECTIVES

The purpose of this study is to determine if the use of a specific prostaglandin endoperoxide-2 inhibitor will prevent luteal development in women.

STUDY DESIGN

Ovulatory reproductive-aged women not using or needing hormonal contraception were prospectively followed for three menstrual cycles. Women were randomized into two groups using a crossover design [Group 1: control cycle, placebo cycle, active drug (celecoxib 400 mg orally) cycle; Group 2: control cycle, celecoxib cycle, placebo cycle]. Study drug was dosed daily until the onset of the next menses. Demographics, menstrual cycle length and twice-weekly progesterone (P) levels during the placebo and active drug cycles were recorded. End points included the change in luteal phase P levels and menstrual cycle length (days) during active drug exposure.

RESULTS

A total of 11 women completed the study (Group 1, n=7; Group 2, n=4). No demographic differences were found between groups [age, race, body mass index (BMI), control cycle length]. A comparison of the control and active drug cycles for all participants demonstrated a trend toward a longer menstrual cycle with active drug exposure [control, 27.2 days (SD, 2.4); study drug, 28.5 days (SD, 2.5), p=.09]. Five women had a delay in the rise of their luteal phase P levels, two women had lower peak P levels and two women had no elevation of luteal phase P levels during active drug cycle as compared to placebo cycle.

CONCLUSION

Daily administration of a prostaglandin synthesis inhibitor may delay the timing of luteal events and, therefore, fertility in women. PTGS2 inhibitors may hold potential as an emergency contraceptive.

Family planning: today and in the future

This review covers the state of contraceptive development noting new entries in the clinic (mainly steroidal and different delivery methods) and novel leads for nonsteroidal female- and male-methods in the pipeline. The time taken to market and the absence of partnerships with industry are stressed as major factors for the slow progress in their development.

[Pregnancy results in in vitro fertilization in one case of luteinized-unruptured-follicle syndrome]

Luteinized unruptured follicle syndrome can explain female infertility. The precise mechanism by which the ovulatory follicle fails to rupture is unclear. The following case reports a pregnancy result in in vitro fertilization (IVF). The first stimulation, a long IVF protocol with low FSH dose, was successful. Different methods used for detection and treatment are discussed.

Angiogenesis and antiangiogenic therapy in endometriosis

Endometriosis, the presence of endometrium-like tissue outside of the uterine cavity, is a common disease among women of reproductive age. Typical symptoms include abdominal pain and painful menstruation. In addition, endometriosis is associated with reduced fertility. Current treatment modalities, the surgical removal of endometriotic lesions and the hormonal suppression of estrogen are associated with significant morbidity, side-effects and recurrence rates. Despite uncertainties about the pathophysiology of the disease it has recently become apparent that angiogenesis plays a pivotal role in endometriosis. This review focuses on a multitude of factors involved in the angiogenic phenotype of endometriosis demonstrating that many biological systems such as the immune system and steroid hormones are closely connected to angiogenic pathways in this disease. In addition, experimental and clinical data are discussed that concentrate on the inhibition of angiogenesis as a novel therapeutic approach for endometriosis.

The rodent estrous cycle: characterization of vaginal cytology and its utility in toxicological studies

While an evaluation of the estrous cycle in laboratory rodents can be a useful measure of the integrity of the hypothalamic-pituitary-ovarian reproductive axis, it can also serve as a way of insuring that animals exhibiting abnormal cycling patterns are disincluded from a study prior to exposure to a test compound. Assessment of vaginal cytology in regularly cycling animals also provides a means to establish a comparable endocrine milieu for animals at necropsy. The procedure for obtaining a vaginal smear is relatively non-invasive and is one to which animals can become readily accustomed. It requires few supplies, and with some experience the assessments can be easily performed in fresh, unstained smears, or in fixed, stained ones. When incorporated as an adjunct to other endpoint measures, a determination of a female's cycling status can contribute important information about the nature of a toxicant insult to the reproductive system. In doing so, it can help to integrate the data into a more comprehensive mechanistic portrait of the effect, and in terms of risk assessment, may provide some indication of a toxicant's impact on human reproductive physiology.

Regulation, action and transport of prostaglandins during the periovulatory period in cattle

Follicular production of prostaglandins (PGs) is essential for mammalian ovulation, but the factors that mediate production and the cell-specific action(s) of PGE and PGF2alpha during the ovulatory cascade remain largely unknown. The aims of these experiments were: (1) to investigate the potential role of oxytocin (OT) in ovulatory PG production, (2) to determine cellular and temporal patterns of expression of mRNA for specific PG receptors during the periovulatory interval, (3) to determine cell-specific effects of PGE2 on progesterone secretion, and (4) to investigate the potential for an active transport mechanism that may regulate the effect of PGs during the ovulatory cascade, using cattle as the animal model. Heifers were treated sequentially with PGF2alpha and GnRH to induce luteal regression, a follicular phase and the LH/FSH surge (ovulation occurs approximately 30 h after GnRH). In experiment 1, OT increased the secretion of PGE and PGF2alpha by granulosa cells collected from preovulatory follicles (before the LH/FSH surge) and OT production by pieces of follicle wall from periovulatory follicles (after the LH/FSH surge) was regulated by progesterone acting through the progesterone receptor. In experiment 2, levels of mRNA for the PGF2alpha receptor and three PGE receptor subtypes were determined by semi-quantitative RT-PCR in theca interna and granulosa cells from pre- and periovulatory follicles collected at 0, 6, 12, 18 and 24 h post-GnRH. Time- and cell-specific patterns of change in mRNA for PG receptors were observed, suggesting multiple effects of both PGE and PGF2alpha in both theca interna and granulosa cells throughout the ovulatory cascade. Cell-specificity of PG action was confirmed in experiment 3; PGE2 increased the secretion of progesterone by theca interna but not granulosa cells collected from late periovulatory follicles. The results of experiment 4 revealed the expression of mRNA for the bovine PG transporter in theca interna and granulosa cells and its regulation during the periovulatory period, thus revealing the presence of a potential transport mechanism that could regulate cellular distribution of PGs throughout the ovulatory cascade. Taken together, these results provide new insight into mechanisms that regulate the production, distribution and site of action of PGE and PGF2alpha during the ovulatory cascade.