Features of natural and gonadotropin-releasing hormone antagonist-induced corpus luteum regression and effects of in vivo human chorionic gonadotropin

Functional role of autophagy in testicular and ovarian steroidogenesis

Autophagy is an evolutionarily conserved cellular recycling process that maintains cellular homeostasis. Despite extensive research in endocrine contexts, the role of autophagy in ovarian and testicular steroidogenesis remains elusive. The significant role of autophagy in testosterone production suggests potential treatments for conditions like oligospermia and azoospermia. Further, influence of autophagy in folliculogenesis, ovulation, and luteal development emphasizes its importance for improved fertility and reproductive health. Thus, investigating autophagy in gonadal cells is clinically significant. Understanding these processes could transform treatments for endocrine disorders, enhancing reproductive health and longevity. Herein, we provide the functional role of autophagy in testicular and ovarian steroidogenesis to date, highlighting its modulation in testicular steroidogenesis and its impact on hormone synthesis, follicle development, and fertility therapies.

A matter of new life and cell death: programmed cell death in the mammalian ovary

BACKGROUND

The mammalian ovary is a unique organ that displays a distinctive feature of cyclic changes throughout the entire reproductive period. The estrous/menstrual cycles are associated with drastic functional and morphological rearrangements of ovarian tissue, including follicular development and degeneration, and the formation and subsequent atrophy of the corpus luteum. The flawless execution of these reiterative processes is impossible without the involvement of programmed cell death (PCD).

MAIN TEXT

PCD is crucial for efficient and careful clearance of excessive, depleted, or obsolete ovarian structures for ovarian cycling. Moreover, PCD facilitates selection of high-quality oocytes and formation of the ovarian reserve during embryonic and juvenile development. Disruption of PCD regulation can heavily impact the ovarian functions and is associated with various pathologies, from a moderate decrease in fertility to severe hormonal disturbance, complete loss of reproductive function, and tumorigenesis. This comprehensive review aims to provide updated information on the role of PCD in various processes occurring in normal and pathologic ovaries. Three major events of PCD in the ovary-progenitor germ cell depletion, follicular atresia, and corpus luteum degradation-are described, alongside the detailed information on molecular regulation of these processes, highlighting the contribution of apoptosis, autophagy, necroptosis, and ferroptosis. Ultimately, the current knowledge of PCD aberrations associated with pathologies, such as polycystic ovarian syndrome, premature ovarian insufficiency, and tumors of ovarian origin, is outlined.

CONCLUSION

PCD is an essential element in ovarian development, functions and pathologies. A thorough understanding of molecular mechanisms regulating PCD events is required for future advances in the diagnosis and management of various disorders of the ovary and the female reproductive system in general.

The role of estrogen metabolites in human ovarian function

Estrogens produced by the ovary play diverse roles in controlling physiological changes in the function of the female reproductive system. Although estradiol acts through classical nuclear receptors, its metabolites (EMs) act by alternative pathways. It has been postulated that EMs act through paracrine-autocrine pathways to regulate key processes involved in normal follicular growth, corpus luteum (CL) development, function, and regression. The present review describes recent advances in understanding the role of EMs in human ovarian physiology during the menstrual cycle, including their role in anovulatory disorders and their action in other target tissues.

Apoptosis, autophagic cell death, and necroptosis: different types of programmed cell death in bovine corpus luteum regression

In mammals, the corpus luteum (CL) is a transient organ that secretes progesterone (P4). In the absence of pregnancy, the CL undergoes regression (luteolysis), which is a crucial preparation step for the next estrous cycle. Luteolysis, initiated by uterine prostaglandin F_2α (PGF) in cattle, is usually divided into two phases, namely functional luteolysis characterized by a decline in P4 concentration and structural luteolysis characterized by the elimination of luteal tissues from the ovary. Programmed cell death (PCD) of luteal cells, including luteal steroidogenic cells (LSCs) and luteal endothelial cells (LECs), plays a crucial role in structural luteolysis. The main types of PCD are caspase-dependent apoptosis (type 1), autophagic cell death (ACD) via the autophagy-related gene (ATG) family (type 2), and receptor-interacting protein kinase (RIPK)-dependent programmed necrosis (necroptosis, type 3). However, these PCD signaling pathways are not completely independent and interact with each other. Over the past several decades, most studies on luteolysis have focused on apoptosis as the principal mode of bovine luteal cell death. Recently, ATG family members were reported to be expressed in bovine CL, and their levels increased during luteolysis. Furthermore, the expression of RIPKs, which are crucial mediators of necroptosis, is reported to increase in bovine CL during luteolysis and is upregulated by pro-inflammatory cytokines in bovine LSCs and LECs. Therefore, apoptosis, ACD, and necroptosis may contribute to bovine CL regression. In this article, we present the recent findings regarding the mechanisms of the three main types of PCD and the contribution of these mechanisms to luteolysis.

Autophagy in hypoxic ovary

Oxygen deprivation affects human health by modulating system as well as cellular physiology. Hypoxia generates reactive oxygen species (ROS), causes oxidative stress and affects female reproductive health by altering ovarian as well as oocyte physiology in mammals. Hypoxic conditions lead to several degenerative changes by inducing various cell death pathways like autophagy, apoptosis and necrosis in the follicle of mammalian ovary. The encircling somatic cell death interrupts supply of nutrients to the oocyte and nutrient deprivation may result in the generation of ROS. Increased level of ROS could induce granulosa cells as well as oocyte autophagy. Although autophagy removes damaged proteins and subcellular organelles to maintain the cell survival, irreparable damages could induce cell death within intra-follicular microenvironment. Hypoxia-induced autophagy is operated through 5' AMP activated protein kinase-mammalian target of rapamycin, endoplasmic reticulum stress/unfolded protein response and protein kinase C delta-c-junN terminal kinase 1 pathways in a wide variety of somatic cell types. Similar to somatic cells, we propose that hypoxia may induce granulosa cell as well as oocyte autophagy and it could be responsible at least in part for germ cell elimination from mammalian ovary. Hypoxia-mediated germ cell depletion may cause several reproductive impairments including early menopause in mammals.

Coherent apoptotic and autophagic activities involved in regression of chicken postovulatory follicles

After ovulation in mammals, rupture of mature follicles is reorganized into the corpus luteum that secrets progesterone (P₄) to stimulate endometrial development. The situation in birds differs considerably. Beyond ovulation the ruptured avian follicle forms a postovulatory follicle (POF) that is not considered analogous to mammalian corpus luteum. The function and regression mechanisms of avian POFs remain poorly understood. Here we investigated the changes in apoptotic and autophagic activities that were involved during POF degradation. Results showed that the structure and secretory function of POF3 manifested the most apparent deterioration during whole processes of regression. A TUENL assay revealed that the granulosa layer maintained longer viability than the theca layer. Importantly, mitochondrial apoptosis and endoplasmic reticulum (ER) stress-associated genes and proteins reached their highest levels in the granulosa cells of POF3. Beclin1 was distributed mainly in theca cells and coupled with LC3β-II accumulation, Sequestosome-1 (p62) degradation and Beclin1 elevation confirmed that autophagic activity had increased dramatically in the theca layer of POFs. These results indicate that the apoptosis of the granulosa cells from POFs occurs by mitochondrial apoptosis and ER stress and that a coherence of Beclin1-induced autophagy and caspase-induced apoptosis results in regression of theca layers of avian POFs.

AG 205, a progesterone receptor membrane component 1 antagonist, ablates progesterone's ability to block oxidative stress-induced apoptosis of human granulosa/luteal cells†

The present studies were designed to determine whether progesterone (P4)-progesterone receptor membrane component 1 (PGRMC1) signaling is able to attenuate the apoptotic effects of oxidative stress induced by hydrogen peroxide (H2O2). To achieve this goal, freshly isolated human granulosa/luteal cells were maintained in culture. After several passages, the cells were treated with H2O2, which induced apoptosis within 2.5 h, while simultaneous treatment with P4 attenuated the apoptotic action of H2O2. AG 205, a PGRMC1 antagonist, eliminated P4's ability to prevent H2O2-induced apoptosis. AG 205 neither affected PGRMC1's cytoplasmic localization nor its interaction with PGRMC2, but appeared to reduce its presence within the nucleus. AG 205 also (1) increased the monomeric and decreased the higher molecular weight forms of PGRMC1 (i.e., dimers/oligomers) and (2) altered the expression of several genes involved in apoptosis. The most dramatic change was an approximate 8-fold increase in Harakiri (Hrk) mRNA. However, AG 205 did not induce apoptosis in the absence of H2O2. Taken together, these observations suggest that the higher molecular weight forms of PGRMC1 likely account in part for PGRMC1's ability to suppress the expression of Hrk. Harakiri is a BH-3 only member of the B-cell lymphoma 2 (BCL2) family that promotes apoptosis by binding to and antagonizing the antiapoptotic action of BCL2- and BCL2-like proteins. It is likely then that PGRMC1's ability to suppress Hrk is part of the mechanism through which P4-PGRMC1 signaling preserves the viability of human granulosa/luteal cells.

PGRMC1 localization and putative function in the nucleolus of bovine granulosa cells and oocytes

Progesterone receptor membrane component-1 (PGRMC1) is a highly conserved multifunctional protein that is found in numerous systems, including reproductive system. Interestingly, PGRMC1 is expressed at several intracellular locations, including the nucleolus. The aim of this study is to investigate the functional relationship between PGRMC1 and nucleolus. Immunofluorescence experiments confirmed PGRMC1's nucleolar localization in cultured bovine granulosa cells (bGC) and oocytes. Additional experiments conducted on bGC revealed that PGRMC1 co-localizes with nucleolin (NCL), a major nucleolar protein. Furthermore, small interfering RNA (RNAi)-mediated gene silencing experiments showed that when PGRMC1 expression was depleted, NCL translocated from the nucleolus to the nucleoplasm. Similarly, oxidative stress induced by hydrogen peroxide (H2O2) treatment, reduced PGRMC1 immunofluorescent signal in the nucleolus and increased NCL nucleoplasmic signal, when compared to non-treated cells. Although PGRMC1 influenced NCL localization, a direct interaction between these two proteins was not detected using in situ proximity ligation assay. This suggests the involvement of additional molecules in mediating the co-localization of PGRMC1 and nucleolin. Since nucleolin translocates into the nucleoplasm in response to various cellular stressors, PGRMC1's ability to regulate its localization within the nucleolus is likely an important component of mechanism by which cells response to stress. This concept is consistent with PGRMC1's well-described ability to promote ovarian cell survival and provides a rationale for future studies on PGRMC1, NCL and the molecular mechanism by which these two proteins protect against the adverse effect of cellular stressors, including oxidative stress.

Early transcriptome responses of the bovine midcycle corpus luteum to prostaglandin F2α includes cytokine signaling

In ruminants, prostaglandin F2alpha (PGF2α)-mediated luteolysis is essential prior to estrous cycle resumption, and is a target for improving fertility. To deduce early PGF2α-provoked changes in the corpus luteum a short time-course (0.5-4 h) was performed on cows at midcycle. A microarray-determined transcriptome was established and examined by bioinformatic pathway analysis. Classic PGF2α effects were evident by changes in early response genes (FOS, JUN, ATF3) and prediction of active pathways (PKC, MAPK). Several cytokine transcripts were elevated and NF-κB and STAT activation were predicted by pathway analysis. Self-organizing map analysis grouped differentially expressed transcripts into ten mRNA expression patterns indicative of temporal signaling cascades. Comparison with two analogous datasets revealed a conserved group of 124 transcripts similarly altered by PGF2α treatment, which both, directly and indirectly, indicated cytokine activation. Elevated levels of cytokine transcripts after PGF2α and predicted activation of cytokine pathways implicate inflammatory reactions early in PGF2α-mediated luteolysis.

The significance of estradiol metabolites in human corpus luteum physiology

The human corpus luteum (CL) is a temporary endocrine gland derived from the ovulated follicle. Its formation and limited lifespan is critical for steroid hormone production required to support menstrual cyclicity, endometrial receptivity for successful implantation, and the maintenance of early pregnancy. Endocrine and paracrine-autocrine molecular mechanisms associated with progesterone production throughout the luteal phase are critical for the development, maintenance, regression, and rescue by hCG which sustains CL function into early pregnancy. However, the signaling systems driving the regression of the primate corpus luteum in non-conception cycles are not well understood. Recently, there has been interest in the functional roles of estradiol metabolites (EMs), mostly in estrogen-producing tissues. The human CL produces a number of EMs, and it has been postulated that the EMs acting via paracrine-autocrine pathways affect angiogenesis or LH-mediated events. The present review describes advances in understanding the role of EMs in the functional lifespan and regression of the human CL in non-conception cycles.

Gonadotropin releasing hormone antagonist administration for treatment of early type severe ovarian hyperstimulation syndrome: a case series

Objective

To report an efficacy of gonadotropin releasing hormone (GnRH) antagonist administration after freezing of all embryos for treatment of early type ovarian hyperstimulation syndrome (OHSS).

Methods

In 10 women who developed fulminant early type OHSS after freezing of all embryos, GnRH antagonist (cetrorelix 0.25 mg per day) was started at the time of hospitalization and continued for 2 to 4 days. Fluid therapy and drainage of ascites was performed as usual.

Results

Early type OHSS was successfully treated without any complication. At hospitalization, the median (95% confidence interval [CI]) of the right and the left ovarian diameter was 10.0 cm (7.6 to 12.9 cm) and 8.5 cm (7.5 to 12.6 cm). After completion of GnRH antagonist administration, it was decreased to 7.4 cm (6.2 to 10.7 cm) (P=0.028) and 7.8 cm (5.7 to 12.2 cm) (P=0.116), respectively. The median duration of hospital stay was 6 days (3 to 11 days). Trans-abdominal drainage of ascites was performed in 2 women and drainage of ascites by percutaneous indwelling catheter was performed in 4 women. No side effect of GnRH antagonist was noted.

Conclusion

GnRH antagonist administration appears to be safe and effective for women with fulminant early type OHSS after freezing all embryos. Optimal dose or duration of GnRH antagonist should be further determined.

Regulation of endothelial permeability in the primate corpora lutea: implications for ovarian hyperstimulation syndrome

In a developing human corpus luteum, a closely regulated cellular communication system exists between the luteal steroidogenic cells and endothelial cells. This system guaranties the vascularization process during luteal formation. The process is combined with rapid release of large amounts of progesterone into the bloodstream. The regulation of endothelial proliferation and permeability by LH and human chorionic gonadotropin (hCG) is integral to this process. On the cellular level, endothelial permeability is regulated by intercellular junctions, such as adherens junctions (AJ) and tight junctions (TJ), which act as zipper-like structures between interacting endothelial cells. Several cell junctional proteins are localized to the corpus luteum, including Occludin, Nectin 2, Claudin 1, and Claudin 5, as well as, vascular endothelial (VE)-Cadherin. It has been assumed that regulation of AJ- and TJ-proteins is of particular importance for permeability, and accordingly, for the functionality of the corpus luteum in early pregnancy, because treatment with hCG induces downregulation of juntional proteins in the luteal vessels. The effect of hCG on the adhesive molecules is mediated by VE growth factor (VEGF). On a functional level, the hCG-dependent and VEGF-mediated decrease in junctional proteins causes a decrease in the density of cell-cell closure and, accordingly, an increase in endothelial permeability. In doing so, the different junctional proteins are not only directly influenced by VEGF but also interact among themselves and influence each other reciprocally. Disturbances in this strictly, regulated interactions may explain the development of pathologies with increased vascular permeability, such as the ovarian hyperstimulation syndrome.

Autophagy in the endocrine glands

Autophagy is an important cellular process involving the degradation of intracellular components. Its regulation is complex and while there are many methods available, there is currently no single effective way of detecting and monitoring autophagy. It has several cellular functions that are conserved throughout the body, as well as a variety of different physiological roles depending on the context of its occurrence in the body. Autophagy is also involved in the pathology of a wide range of diseases. Within the endocrine system, autophagy has both its traditional conserved functions and specific functions. In the endocrine glands, autophagy plays a critical role in controlling intracellular hormone levels. In peptide-secreting cells of glands such as the pituitary gland, crinophagy, a specific form of autophagy, targets the secretory granules to control the levels of stored hormone. In steroid-secreting cells of glands such as the testes and adrenal gland, autophagy targets the steroid-producing organelles. The dysregulation of autophagy in the endocrine glands leads to several different endocrine diseases such as diabetes and infertility. This review aims to clarify the known roles of autophagy in the physiology of the endocrine system, as well as in various endocrine diseases.

Regulation of Endothelial Permeability in the Corpus Luteum: A Review of the Literature

The development of the human corpus luteum (yellow body) is dictated by a strictly controlled system of mutually communicating cells, the luteal steroid hormone-producing cells and endothelial cells. This cell-to-cell communication facilitates control of neoangiogenesis which is a prerequisite for the development of the corpus luteum and its function, the rapid release of large amounts of progesterone into the blood-vascular system. Preconditions for this process are the hormonal regulation of endothelial cell proliferation as well as of vascular permeability through LH and hCG. The morphological correlates of endothelial permeability are cell-to-cell adhesion molecules such as adherens junctions (AJ) and tight junctions (TJ) that open and close the gaps between mutually interacting, neighbouring endothelial cells like a "zip fastener". Various types of cell adhesion molecules have been detected in the corpus luteum such as occludin, claudin 1 and claudin 5 as well as VE-cadherin. It may be assumed that the regulation of AJ and TJ proteins is of particular importance for the permeability and thus for the function of the corpus luteum in early pregnancy since hCG treatment leads to a down-regulation of cell adhesion molecules in the luteal vessels. This effect is apparently mediated by VEGF. From a functional point of view, the hCG-dependent and VEGF-mediated down-regulation of cell adhesion molecules leads to a reduced transmissibility of cell-to-cell contacts and thus to an increased endothelial permeability. In this process the various cell adhesion molecules are not only directly regulated by VEGF but they also mutually interact and thus influence one another.

Normal and tumour cervical cells respond differently to vaginal lactobacilli, independent of pH and lactate

Cervical cancer is a human papilloma virus (HPV)-related cancer, but most HPV infections are transient or intermittent and resolve spontaneously. Thus, other factors, such as cervical microflora, which are dominated by lactobacilli, must be involved in invasive cervical carcinoma development after HPV infection. Previous studies have demonstrated that lactobacilli have antitumour effects, and it is possible that vaginal lactobacilli prevent cervical cancer. Here we examined the proliferative and apoptotic responses of normal and tumour cervical cells to common vaginal lactobacilli components by investigating human normal fibroblast-like cervical (normal cervical) and HeLa (cervical tumour) cell responses to Lactobacillus gasseri and Lactobacillus crispatus. The effects of different lactobacilli components, such as culture supernatants, cytoplasmic extracts, cell-wall extracts and live cells, were determined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, trypan blue staining, lactate dehydrogenase assay and colorimetric caspase-3 activity assay. Changes in caspase-3 and human chorionic gonadotropin β (hCGβ) expression were analysed by quantitative RT-PCR. Tumour cell growth inhibition by culture supernatants was higher than that by pH- and lactate-adjusted controls. However, the effects of the supernatants on normal cells were similar to those of lactate-adjusted controls. Apoptosis was inhibited by supernatants, which was consistent with higher hCGβ expression since hCG inhibits apoptosis. Our study demonstrated that common vaginal lactobacilli exert cytotoxic effects on cervical tumour cells, but not on normal cells, and that this cytotoxicity is independent of pH and lactate. Our results encourage further studies on the interaction between lactobacilli and cervical cells, and administration of common vaginal lactobacilli as probiotics.

Large animal models for the study of ovarian follicular dynamics in women

Initial studies of the ovaries were based on postmortem anatomic descriptions, followed by histologic and endocrine approaches. The introduction of high-resolution ultrasonography provided a long-awaited tool to image the reproductive tissues in situ in both animals and humans. Critical studies of the characteristics and control of ovarian follicular and luteal dynamics in nonhuman primates, rodents, and domestic farm animals have involved frequent (i.e., daily or multiple times a day) blood sampling and ultrasonography. Studies of this nature in women are difficult, and often unethical to conduct. Differences in antral folliculogenesis between humans and animals appear to be more in detail rather than in essence, and may reflect differences in intrinsic physiology or merely differences in our ability to detect changes in a given species. In women, the presence of endometrial shedding and symmetric luteal and follicular phases are different from that observed during the estrous cycles of domestic farm animals but despite these differences, general similarities in antral follicular dynamics exist. A continuous pattern of antral follicle development was originally proposed in domestic livestock species; however, the use of frequent serial ultrasonography and simultaneous endocrine profiling in these animal species has resulted in a broad understanding of follicular wave dynamics. Follicular waves have now been described in every species in which this approach has been used, including humans. The relatively large diameters of antral follicles in cows and mares, compared with monkeys, sheep, and rodents provide greater feasibility for characterizing antral follicular dynamics ultrasonographically. While the use of large animal models has increased our understanding of ovarian function and provides the hypothetical basis for studies in women, differences in vocabulary, culture, and research methodologies has hampered knowledge translation. These differences represent a systemic impediment to a broad understanding of ovarian function and limits progress and innovation in the development of safer and more efficacious treatments for infertility and contraception.

Five different phenotypes of endothelial cell cultures from the bovine corpus luteum: present outcome and role of potential dendritic cells in luteolysis

Progress in understanding the background of structural luteolysis depends on insights into the physiological function of innate immunity (INIM), in particular the presence of dendritic cells (DCs) in the corpus luteum (CL). For this reason, the cultures of five endothelial cell-like phenotypes derived from the bovine CL and their long-lasting analysis (morphology, function, and origin) become important. Types 1 and 2 represent microvascular endothelial cells with cytokeratin (CK) expression, assumed to be danger-sensing cells. Types 3 and 4 express features of common endothelial cells. Type 5 indicates a steroidogenic cell type, which could be derived from steroidogenic CK(+) cells in the CL of development after loss of CK expression. Type 5 is a promising candidate to become a mature DC. It might act with the microvascular CK(+) cell/type 1 like a luteovascular unit, which connects INIM with adaptive/cell-mediated immunity (ADIM) in structural luteolysis.

Human chorionic gonadotropin up-regulates expression of myeloid cell leukemia-1 protein in human granulosa-lutein cells: implication of corpus luteum rescue and ovarian hyperstimulation syndrome

CONTEXT

The corpus luteum is a dynamic endocrine structure with periodic development and regression during menstrual cycles. Its lifespan can be prolonged by human chorionic gonadotropin (hCG). However, the signal mechanisms of this phenomenon remain unclear.

OBJECTIVE

Our objective was to investigate the molecular mechanisms of hCG in the maintenance of the viability of granulosa-lutein cells.

DESIGN

Granulosa-lutein cells were obtained from women undergoing in vitro fertilization. We examined the effects of hCG on the survival of cultured granulosa-lutein cells. The signal pathway inducing antiapoptotic protein was investigated.

RESULTS

hCG enhanced viability of granulosa-lutein cells through antiapoptosis but not proliferation, because the apoptotic marker of annexin V was decreased, but the proliferative markers of Ki67 and proliferating cell nuclear antigen were not increased. Myeloid cell leukemia-1 (Mcl-1) protein, but not B-cell lymphoma protein-2 or B-cell lymphoma protein-xL, was significantly induced by hCG and LH. The granulosa-lutein cells secreted vascular endothelial growth factor that induced endothelial permeability. Mcl-1 small interfering RNA increased DNA fragmentation and diminished the antiapoptotic effect of hCG. hCG induced Mcl-1 expression through the LH/hCG receptor, adenylate cyclase, protein kinase A, and cAMP response element-binding protein signal pathway. Flavopiridol inhibited Mcl-1 production, released cytochrome c, and induced apoptosis of granulosa-lutein cells.

CONCLUSIONS

We first demonstrate that hCG prevents apoptosis of granulosa-lutein cells through the induction of Mcl-1 protein via the LH/hCG receptor and a cAMP response element-binding protein-dependent pathway. We may have found the molecular mechanism for luteal rescue during early pregnancy. Mcl-1 prevents apoptosis and increases cell viability but not proliferation as mechanisms for luteal rescue. Mcl-1 is a key molecule of hCG signaling.

Human corpus luteum physiology and the luteal-phase dysfunction associated with ovarian stimulation

The human corpus luteum is a temporary endocrine gland that develops after ovulation from the ruptured follicle during the luteal phase. It is an important contributor of steroid hormones, particularly progesterone, and is critical for the maintenance of early pregnancy. Luteal-phase dysfunction can result in premature regression of the gland, with a subsequent shift to an infertile cycle. Understanding the mechanism of steroidogenesis during corpus luteum growth and regression is crucial for evaluating the normal physiology and pathophysiology of reproductive cycles. The rate-limiting step in corpus luteum steroidogenesis is the transport of cholesterol to the site of steroid production. Steroidogenic acute regulatory protein is a key player in this process and is positively correlated with progesterone concentrations throughout the early and mid-luteal phase. Changes in the endocrine environment brought on by the gonadotrophins used for ovarian stimulation are thought to underlie the corpus luteum dysfunction associated with IVF cycles. While ovarian hyperstimulation syndrome is associated with human chorionic gonadotrophin (HCG), studies suggest that exogenous progesterone provides necessary luteal support in patients undergoing IVF. The current trend towards simple stimulation protocols and the use of single-embryo transfers provide further opportunity to revisit HCG administration as luteal support.

Genome-wide gene expression analysis reveals a dynamic interplay between luteotropic and luteolytic factors in the regulation of corpus luteum function in the bonnet monkey (Macaca radiata)

Although LH is essential for survival and function of the corpus luteum (CL) in higher primates, luteolysis occurs during nonfertile cycles without a discernible decrease in circulating LH levels. Using genome-wide expression analysis, several experiments were performed to examine the processes of luteolysis and rescue of luteal function in monkeys. Induced luteolysis with GnRH receptor antagonist (Cetrorelix) resulted in differential regulation of 3949 genes, whereas replacement with exogenous LH (Cetrorelix plus LH) led to regulation of 4434 genes (1563 down-regulation and 2871 up-regulation). A model system for prostaglandin (PG) F(2alpha)-induced luteolysis in the monkey was standardized and demonstrated that PGF(2alpha) regulated expression of 2290 genes in the CL. Analysis of the LH-regulated luteal transcriptome revealed that 120 genes were regulated in an antagonistic fashion by PGF(2alpha). Based on the microarray data, 25 genes were selected for validation by real-time RT-PCR analysis, and expression of these genes was also examined in the CL throughout the luteal phase and from monkeys treated with human chorionic gonadotropin (hCG) to mimic early pregnancy. The results indicated changes in expression of genes favorable to PGF(2alpha) action during the late to very late luteal phase, and expressions of many of these genes were regulated in an opposite manner by exogenous hCG treatment. Collectively, the findings suggest that curtailment of expression of downstream LH-target genes possibly through PGF(2alpha) action on the CL is among the mechanisms underlying cross talk between the luteotropic and luteolytic signaling pathways that result in the cessation of luteal function, but hCG is likely to abrogate the PGF(2alpha)-responsive gene expression changes resulting in luteal rescue crucial for the maintenance of early pregnancy.

Ovarian stimulation to cryopreserve fertilized oocytes in cancer patients can be started in the luteal phase

OBJECTIVE

To analyze if oocytes can be obtained in all patients before cancer treatment within 2 weeks by initiating ovarian stimulation during the follicular or luteal phase.

DESIGN

Prospective controlled multicenter trial.

SETTING

Four university-based centers.

PATIENT(S)

Forty cancer patients before chemotherapy.

INTERVENTION(S)

Twenty-eight patients were stimulated with gonadotropins in the follicular phase (group I). In 12 patients (group II), ovarian stimulation was initiated in the luteal phase, and these received GnRH antagonists and recombinant FSH. In 14 patients, 143 oocytes were further processed for fertilization by intracytoplasmic sperm injection (ICSI).

MAIN OUTCOME MEASURE(S)

Number of oocytes aspirated after ovarian stimulation, cumulative FSH/hMG dosage, viability and maturity of oocytes, and fertilization rate by ICSI.

RESULT(S)

Patients in group I (age 27.6 +/- 4.9 yrs) were stimulated on average for 10.6 days, and patients in group II (age 31.2 +/- 5.7 yrs) for 11.4 days. Total amount of FSH was on average 2,255 IU (I) and 2,720 IU (II) per patient. Average and median numbers of aspirated oocytes were, respectively, 13.1 and 11.5 (I) versus 10.0 and 8.5 (II); 83.7% (I) and 80.4% (II) of the oocytes were mature and viable and could be treated by ICSI. Fertilization rate was 61.0% (I) versus 75.6% (II).

CONCLUSION(S)

This pilot study suggests that oocytes can be obtained before cancer treatment efficiently irrespective of the phase of the menstrual cycle.

Activation of Cl- channels by human chorionic gonadotropin in luteinized granulosa cells of the human ovary modulates progesterone biosynthesis

Chloride permeability pathways and progesterone (P4) secretion elicited by human chorionic gonadotropin (hCG) in human granulosa cells were studied by electrophysiological techniques and single-cell volume, membrane potential and Ca2+i measurements. Reduction in extracellular Cl(-) and equimolar substitution by the membrane-impermeant anions glutamate or gluconate significantly increased hCG-stimulated P4 accumulation. A similar result was achieved by exposing the cells to hCG in the presence of a hypotonic extracellular solution. Conversely, P4 accumulation was drastically reduced in cells challenged with hCG exposed to a hypertonic solution. Furthermore, conventional Cl(-) channel inhibitors abolished hCG-mediated P4 secretion. In contrast, 25-hydroxycholesterol-mediated P4 accumulation was unaffected by Cl(-) channel blockers. In human granulosa cells, hCG triggered the activation of a tamoxifen-sensitive outwardly rectifying Cl(-) current comparable to the volume-sensitive outwardly rectifying Cl(-) current. Exposure of human granulosa cells to hCG induced a rapid 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid-sensitive cell membrane depolarization that was paralleled with an approximately 20% decrease in cell volume. Treatment with hCG evoked oscillatory and nonoscillatory intracellular Ca2+ signals in human granulosa cells. Extracellular Ca2+ removal and 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid abolished the nonoscillatory component while leaving the Ca2+ oscillations unaffected. It is concluded that human granulosa cells express functional the volume-sensitive outwardly rectifying Cl(-) channels that are activated by hCG, which are critical for plasma membrane potential changes, Ca2+ influx, and P4 production.