Autophagy in the corpus luteum correlates with tissue growth in pregnant rats.

The developmental activation of the corpus luteum (CL) structurally and functionally is critical for the temporally regulated establishment, maintenance, and termination of pregnancy in rats. In this study, we have investigated the possible involvement of autophagy in the regulation of the CL during pregnancy in rats. The expression ratio of microtubule-associated protein light chain 3 (LC3)-II/-I, a widely used indicator of autophagic activity, in the CL remained relatively stable until day 15 of pregnancy. Subsequently, it progressively increased until day 21, and then declined until day 3 postpartum. This fluctuation was closely associated with the tissue weight of the CL rather than progesterone (P4) production activity. Light and electron microscopy revealed the presence of immunoreactive LC3 aggregates and irregularly shaped autolysosome-like microstructures in the cytoplasm of luteal cells during late pregnancy. Notably, a bolus intrabursal injection of the autophagy inhibitor bafilomycin A1 on day 15 of pregnancy resulted in a significant reduction in luteal cell size and disrupted the normal alteration of circulating P4 levels. Consequently, treatment with this inhibitor increased the likelihood of the varied timing (both advanced and delayed) of delivery and led to reduced body weight in neonates when compared with the vehicle-treated control group. Our findings suggest that autophagy in the rat CL contributes to luteal tissue growth, influences P4 production, and thereby fine-tunes the regulation of gestation length in rats.

Unraveling the role of lipid droplets and perilipin 2 in bovine luteal cells.

Steroidogenic tissues contain cytosolic lipid droplets that are important for steroidogenesis. Perilipin 2 (PLIN2), a structural coat protein located on the surface of lipid droplets in mammalian cells, plays a crucial role in regulating lipid droplet formation and contributing to various cellular processes such as lipid storage and energy homeostasis. Herein, we examine the role that PLIN2 plays in regulating progesterone synthesis in the bovine corpus luteum. Utilizing gene array databases and Western blotting, we have delineated the expression pattern of PLIN2 throughout the follicular to luteal transition. Our findings reveal the presence of PLIN2 in both ovarian follicular and steroidogenic luteal cells, demonstrating an increase in its levels as follicular cells transition into the luteal phase. Moreover, the depletion of PLIN2 via siRNA enhanced progesterone production in small luteal cells, whereas adenovirus-mediated overexpression of both PLIN2 and Perilipin 3 (PLIN3) induced an increase in cytosolic lipid droplet accumulation and decreased hormone-induced progesterone synthesis in these cells. Lastly, in vivo administration of the luteolytic hormone prostaglandin F2α resulted in an upregulation of PLIN2 mRNA and protein expression, accompanied by a decline in serum progesterone. Our findings highlight the pivotal role of PLIN2 in regulating progesterone synthesis in the bovine corpus luteum, as supported by its dynamic expression pattern during the follicular to luteal transition and its responsiveness to luteotropic and luteolytic hormones. We suggest PLIN2 as a potential therapeutic target for modulating luteal function.

The regulation of the expression of prokineticin 1 and its receptors and its mechanism of action in the porcine corpus luteum.

Prokineticin 1 (PROK1) is an important factor in pregnancy establishment in pigs, acting at the embryo-maternal interface and the corpus luteum (CL). Estradiol-17ß (E2) is the primary pregnancy recognition signal in pigs, and its effects are augmented by luteotropic prostaglandin E2 (PGE2). On the contrary, prostaglandin F2α (PGF2α) exerts mainly a luteolytic effect. The present study aimed to elucidate whether E2, PGE2, and PGF2α regulate the expression of PROK1 and its receptors in the porcine CL and to determine the PROK1 effect on luteal endothelial cells and pathways that may be involved in this regulation. The effects of E2, PGE2, and PGF2α on the expressions of PROK1 and its receptors in the CL were studied using an in vitro model of ultrathin luteal tissue explants model. Additionally, the effects of E2 and PGE2 on the PROK1 system were determined using an in vivo approach, in which the hormones were administered into the uterine lumen to imitate their secretion by embryos. Endothelial cell proliferation was measured using the colorimetric method. E2 acting via estrogen receptors simulated the mRNA and protein expressions of PROK1 and PROKR1 in CL explants in vitro (p < 0.05). The simultaneous action of E2 with PGE2 enhanced the expression of luteal PROK1 mRNA in vitro (p < 0.05). Estradiol-17ß acting alone significantly increased PROK1 mRNA levels in vivo, whereas E2 simultaneously administered with PGE2 significantly elevated the PROK1 mRNA expression and PROKR1 mRNA and protein contents in CLs adjacent to uterine horns receiving hormonal infusion compared with CLs adjacent to placebo-treated uterine horns (p < 0.01). The PROK1 protein expression was significantly higher in the CLs of pigs treated with E2, PGE2, and E2 together with PGE2 than in the control group. PGF2α increased the PROK1 mRNA content in CLs on days 12 and 14 of the estrous cycle (p < 0.05). The expression of PROKR2 at the mRNA and protein levels remained unchanged in response to in vitro and in vivo treatments. PROK1 stimulated the proliferation of luteal endothelial cells by activating the MAPK, AKT, and mTOR pathways (p < 0.05). In summary, the luteal expressions of PROK1 and PROKR1 in early pregnancy are regulated by E2 and PGE2. PROK1 stimulates luteal angiogenesis by activating the MAPK, AKT, and mTOR pathways. The regulation of luteal PROK1 expression by PGF2α indicates PROK1's putative role during luteolysis. We conclude that PROK1-PROKR1 signaling supports luteal function during CL rescue in pregnancy in pigs.

Interferon-tau infusion into the ovine corpus luteum delays luteolysis.

Conceptus-derived interferon-tau (IFNT) initiates maternal recognition of pregnancy in ewes by paracrine actions on the endometrium and endocrine action on the corpus luteum (CL). To examine the effect of IFNT on the CL without inducing IFN stimulated genes (ISGs) in the endometrium, recombinant ovine IFNT (roIFNT) or bovine serum albumin (BSA) was delivered directly into CLs via osmotic pumps at a rate of 10, 50 or 100 ng/h from days 9 to 12 of the estrous cycle. Endometrial and CL samples were collected on day 12. Fifty ng/h of roIFNT induced ISG15 in the CL on day 12 without affecting endometrial ISG15 concentrations. In a second experiment, roIFNT (50 ng/h) was infused into the CL from days 10 to 17 of the estrous cycle and serum samples were collected daily. Serum progesterone concentrations were significantly higher on days 15 to 17 in roIFNT-infused ewes compared to controls. Levels of LHCGR, STAR, CYP11A1, HSL, OPA1 and PKA mRNA and proteins were higher in the roIFNT-infused CLs compared to the controls. Levels of ISG15 and MX1 mRNA increased in the CLs of roIFNT-infused ewes but not in the endometrium. Endometrial ESR1 mRNA and protein concentrations were higher in the controls compared to roIFNT-infused ewes. In conclusion, intra-luteal delivery of roIFNT induced ISGs, stabilized steroidogenesis in the CL and delayed luteolysis without inducing endometrial ISGs. Inhibition of ESR1 in the endometrium of roIFNT-infused ewes was observed suggesting that direct delivery of IFNT to the CL has an additional anti-luteolytic effect on the endometrium.

Expression and localization of anti-Müllerian hormone and its receptors in bovine corpus luteum.

Although anti-Müllerian hormone (AMH) is involved in the regulation of granulosa cell function in female animals, its role in tissues other than ovarian follicles remains poorly understood. It has also been suggested that cows with high circulating AMH concentrations have increased fertility; however, the mechanism has not been elucidated. This study was conducted to identify the presence of the AMH-signaling system and its target cells in the bovine corpus luteum formed from an ovulated follicle. Immunoblotting revealed that the proteolytically cleaved C-terminal region in AMH (AMHC), a biologically active peptide, was present in trace amounts in the early corpus luteum and significantly increased during the mid to regressed stages. AMHC and cleaved N-terminal region (AMHN) in AMH generate a noncovalent isoform that improves the activity of AMH signaling. An immunohistochemical analysis revealed that AMHC, AMHN, and type II AMH receptor (AMHR2) were localized to luteal cells during the entire estrous cycle. AMH in the corpus luteum seemed to be newly synthesized since AMH expression was detected. These findings suggest that AMH signaling is involved in the regulation of luteal cell function through an autocrine and post-translational processing mechanism. The level of AMHR2 and mRNA expression of AMHR2 and type I AMH receptors (activin-like kinase 2, 3, and 6) were highest in the mid stage. Thus, AMH signaling in the corpus luteum may also be regulated by changes in the receptor levels. Since the transforming growth factor-beta superfamily, to which AMH belongs, is a multifunctional polypeptide growth factor, further studies are needed to evaluate whether AMH signaling has a role in facilitating or inhibiting luteal cell functions.

Risk assessment of hypertensive disorders of pregnancy and other adverse pregnancy outcomes after frozen embryo transfers following an artificial cycle: A retrospective cohort study.

OBJECTIVES: The primary aim was to investigate if frozen embryo transfer (FET) without a corpus luteum increases the risk of hypertensive disorders of pregnancy (HDP). The secondary aim was to investigate other adverse maternal and perinatal outcomes. METHODS: This was a retrospective cohort study of 1168 singleton pregnancies and live births following a FET with either an artificial cycle (AC-FET) (n = 631) or a natural/modified natural/stimulated cycle (CL-FET) (n = 537) between 2012 and 2020. The data were collected from patient records. The primary outcome was HDP. Secondary outcomes included cesarean sections, placental retention problems, postpartum hemorrhage (PPH), the duration of pregnancy, birth weight, low birth weight, macrosomia, length of gestation, preterm birth, small for gestational age, and large for gestational age. RESULTS: In the AC-FET group, there was an increased incidence of pre-eclampsia, gestational hypertension, cesarean sections, PPH over 500 and 1000 mL, and retained placental tissue, compared with the CL-FET group. These associations remained significant in logistic regression analyses with clinically relevant adjustments. CONCLUSION: The risk of HDP and several other maternal complications seems to be increased after AC-FET compared with CL-FET. Our findings support most earlier studies regarding HDP and add to the knowledge on other maternal and perinatal risks involved in AC-FET, including an increased risk of milder forms of placental retention. More studies are needed to confirm these findings.

Exposure to a Low-Oxygen Environment Causes Implantation Failure and Transcriptomic Shifts in Mouse Uteruses and Ovaries.

Hypoxia is a condition in which tissues of the body do not receive sufficient amounts of oxygen supply. Numerous studies have elucidated the intricate roles of hypoxia and its involvement in both physiological and pathological conditions. This study aimed to clarify the impact of a forced low-oxygen environment in early pregnancy by exposing mice to low-oxygen conditions for 24-72 h after fertilization. The treatment resulted in the complete failure of blastocyst implantation, accompanied by vascular hyperpermeability in the uterus. A transcriptome analysis of the uterus revealed remarkable alterations in gene expression between control normoxic- and hypoxic-treatment groups. These alterations were characterized by the differentially expressed genes categorized into the immune responses and iron coordination. Furthermore, exposure to a low-oxygen environment caused apoptosis in the corpus luteum within the ovary and a reduction in progesterone secretion. Consequently, diminished plasma progesterone levels were considered to contribute to implantation failure in combination with the activation of the hypoxic pathway in the uterus. Additionally, previous studies have demonstrated the impact of hypoxic reactions on blastocyst development and the pre-implantation process in the endometrium. Our findings suggest that the corpus luteum exhibits elevated susceptibility to hypoxia, thereby elucidating a critical aspect of its physiological response.

Is prolonged luteal phase a problem in lactating Holstein cows?

In this study, the main objective was to assess if long luteal phases could have other causes than pregnancy losses. We enrolled Holstein dairy cows ≥50 d in milk (DIM) from a commercial herd in Brazil from October 2016 to August 2017. All cows received an estradiol-based synchronization protocol, and, on the day of insemination (d 0), were randomly assigned either an artificial insemination (AI) or a placebo insemination (PBO) in a 3:1 ratio. An ultrasound was used to assess the presence of a CL on d17, 24, and 31, which, combined to the information from patches for the detection of estrus, was used to determine the length of the luteal phase following AI or PBO. Pregnancy was assessed by ultrasound on d 31 and cows that were pregnant were excluded from the analyses. The length of the estrous cycles was categorized as short (<17 d), normal (17-23 d), long (24-30 d), and very long (≥31 d). We compared the proportion of cows in each category between the AI and PBO groups using a cumulative ordinal mixed model. We define prolonged luteal phase as estrous cycles ≥24 d and tested its association with potential risk factors (parity, season, DIM, uterine size and position score, milk production, body condition score, and the presence of a corpus luteum (CL) at enrollment to the synchronization protocol) using mixed logistic regression models. Results are presented as odds ratio (OR) and 95% credible intervals (BCI). Data from 876 inseminations (AI: n = 616, PBO: n = 260) was collected. Overall, 12% of estrous cycles were short, 31% were normal, 19% were long, and 38% were very long. There was no difference in the odds of being in longer estrous cycle categories for the AI compared with the PBO group (OR = 0.92, 95% BCI = 0.76-1.10). Season and presence of a CL at enrollment were associated with prolonged luteal phase. In the AI group, there was a possible effect of early pregnancy losses on the lifespan of the CL, but not the PBO group, which led us to conclude that long and very long estrous cycles were not all caused by the embryonic loss. In fact, the high prevalence of cows with an extended CL lifespan in the present study suggests this could be an under- or miss-reported characteristic of high-producing lactating Holstein cows. This finding may have important repercussions in the understanding of the CL function physiology of lactating Holstein cows.

Symptomatic corpus luteum hemorrhage in adolescent females with ITP.

Patients with immune thrombocytopenia (ITP) usually present with minor mucocutaneous bleeding. Corpus luteum hemorrhage (CLH) is generally asymptomatic but may, rarely, lead to severe intraperitoneal bleeding, mostly in patients with coagulation disorders. CLH causing intraperitoneal bleeding has only been described in few individuals with ITP. The objective of this retrospective observational study was to assess the clinical course and incidence of symptomatic CLH in adolescent females with newly diagnosed or chronic ITP. Additionally, a comprehensive literature review was conducted to scrutinize cases of pediatric female patients with ITP, complicated by CLH. We identified three patients with ITP and hemoperitoneum secondary to CLH. They presented with acute abdominal pain, had severe thrombocytopenia (platelet counts below 20 × 109/L), and required blood transfusions as well as ITP-directed therapy. All the patients were hemodynamically stable and did not require emergency surgical intervention.  Conclusion: CLH could potentially pose a significant complication in the context of adolescent females with ITP, requiring a strong index of suspicion to direct expedient therapy. What is Known: • Immune thrombocytopenia is typically associated with minor bleeding tendency. • Corpus luteum hemorrhage is generally asymptomatic; however, in women with bleeding disorders, it has the potential to result in substantial intra-abdominal bleeding. What is New: • Corpus luteum hemorrhage leading to intra-abdominal bleeding is a potential severe complication of immune thrombocytopenia in adolescent females.

Clinical features of preeclampsia and hypertensive disorders in pregnancies after different frozen embryo transfer regimens.

OBJECTIVES: To compare whether the clinical features of preeclampsia (PE) or gestational hypertension (GH) were different in pregnancies after a frozen embryo transfer (FET), depending on the FET regimen used. STUDY DESIGN: A retrospective study including 58 pregnancies with PE and 64 pregnancies with GH, all with singleton live births. Pregnancies were stratified according to the presence or absence of a corpus luteum (CL). MAIN OUTCOME MEASURES: Clinical characteristics of PE and GH, maternal background factors, postpartum hemorrhage (PPH), key perinatal outcomes. RESULTS: Among PE patients, no difference was found in the clinical characteristics and in the maternal background factors, when comparing women with a CL to women without a CL. PE patients in the group without a CL had a hemorrhage of > 500 mL or > 1000 mL significantly more often than patients with a CL. Multivariable analyses confirmed this risk. Perinatal outcomes were similar. Among GH patients, there was no difference in the clinical features and maternal background factors, when comparing CL cycles to cycles without a CL. The amount of PPH was higher among the patients without a CL, but the frequency of a > 500 mL or > 1000 mL hemorrhage was similar between groups. No risk increase was seen in multivariable analyses. CONCLUSIONS: Among FET patients with PE, the risk of PPH wasincreased in pregnancies after cycles without a CL, compared to cycles with a CL. The presence or absence of a CL did noteffectthe severity of PE and GH, the duration of pregnancy or blood pressure levels.

Adropin may regulate ovarian functions by improving antioxidant potential in adult mouse.

The corpus luteum (CL) is a temporary endocrine gland that synthesizes progesterone. The luteal progesterone plays a central role in the regulation of the estrous cycle as well as the implantation and maintenance of pregnancy. Our previous study showed the expression of adropin and its receptor, GPR19, in the luteal cells and its significant role in luteinization. The aim of the present study was to investigate the in vitro effect of adropin on hCG-induced ovarian functions in adult mice. We also evaluated the effect of exogenous treatment with adropin on ovarian steroidogenesis and anti-oxidant parameters, with special emphasis on CL function. Our results demonstrated that adropin acts synergistically with hCG to promote ovarian steroidogenesis and survival by increasing the expression of StAR, 3ß-HSD, and aromatase proteins and decreasing the BAX/BCL2 ratio. Exogenous adropin treatment increased progesterone production by increasing the expression of GPR19, StAR and 3ß-HSD enzymes in the mouse ovary. Also, adropin inhibited the luteal oxidative stress by increasing nuclear translocation of NRF-2 in CL, which resulted in increased HO-1 expression and SOD, catalase activity. Decreased oxidative stress might inhibit the translocation of NF-κB into the nucleus of luteal cells, resulting into increased survival and decreased apoptosis, as evident by decreased lipid peroxidation, BAX/BCL2 ratio, caspase 3, active caspase 3 expression, and TUNEL-positive cells in adropin treated mice. Our findings suggest that adropin can be a promising candidate that can enhance the survivability of the CL.

Exposure to atrazine stimulates progesterone secretion and induces oxidative stress, inflammation, and apoptosis in the ovary of pseudopregnant rats.

Atrazine (ATR) is one of the most commonly used herbicides worldwide. As an endocrine disruptor, it causes ovarian dysfunction, but the mechanism is unclear. We hypothesized that ATR could affect ovarian steroidogenesis, oxidative stress, inflammation, and apoptosis. In the current study, rats aged 28 days were treated with PMSG and HCG to obtain amounts of corpora lutea. Then, rats were injected with ATR (50 mg/kg/day) or saline (0.9%) for 7 days. Sera were collected to detect biochemical indices and progesterone (P4) level, ovaries were collected for antioxidant status, HE, qPCR, and WB analysis. Results showed that ATR exposure affected growth performance as well as serum TP, GLB, and ALB levels, increased serum P4 level and ovarian mRNA and protein levels of StAR, CYP11A1, and HSD3B. ATR treatment increased ovarian mRNA and protein levels of CREB but not PKA expression. ATR treatment increased ovarian mRNA abundances of Nrf-2 and Nqo1, MDA level, and decreased SOD, GST, and T-AOC levels. ATR exposure increased the mRNA abundances of pro-inflammatory cytokines including Tnf-α, Il-1ß, Il-6, Il-18, and Inos. ATR exposure increased the mRNA and protein level of Caspase 3 and the ratio of BAX/BCL-2. In conclusion, NRF-2/NQO1 signaling pathway and CREB might be involved in the regulation of ATR in luteal steroidogenesis, oxidative stress, inflammation, and apoptosis in rat ovary.

Angiogenesis and Apoptosis: Data Comparison of Similar Microenvironments in the Corpus Luteum and Tumors.

The corpus luteum is a temporary endocrine gland formed in the ovary after ovulation, and it plays a critical role in animal reproductive processes. Tumors rely on the development of an adequate blood supply to ensure the delivery of nutrients and oxygen and the removal of waste products. While angiogenesis occurs in various physiological and pathological contexts, the corpus luteum and tumors share similarities in terms of the signaling pathways that promote angiogenesis. In the corpus luteum and tumors, apoptosis plays a crucial role in controlling cell numbers and ensuring proper tissue development and function. Interestingly, there are similarities between the apoptotic-regulated signaling pathways involved in apoptosis in the corpus luteum and tumors. However, the regulation of apoptosis in both can differ due to their distinct physiological and pathological characteristics. Thus, we reviewed the biological events of the corpus luteum and tumors in similar microenvironments of angiogenesis and apoptosis.

Effects of Mixed Pasture Legume Phytoestrogens on Superovulatory Response and Embryo Quality in Angus Cows.

Ovulation and artificial insemination rates have been observed to decrease in sheep and cows when exposed to dietary phytoestrogens at concentrations greater than 25 mg/kg DM. A grazing trial was undertaken to investigate the effects of coumestrol and other key phytoestrogens on the superovulatory response, embryo numbers and quality in beef cows grazing legume pastures. A 7-week controlled grazing trial was conducted with legume and ryegrass pasture treatments, with cows exposed to legumes at two timed treatments, 4 and 7 weeks. Twenty Angus cows were subjected to a conventional estrus synchronization and superovulation protocol. Embryos were recovered via conventional uterine body flushing 7 days post artificial insemination (AI). Numerous phytoestrogens were identified in both pasture and plasma samples, including coumestrol and formononetin. Concentrations of phytoestrogens in the pasture ranged from 0.001 to 47.5 mg/kg DM and 0 to 2.6 ng/mL in plasma. Approximately 50% of cows produced viable embryos 7 days post AI. A significant interaction between the effect of treatment groups on the embryo stage was observed (p < 0.05). The results suggest that concentrations of >25 mg/kg DM of phytoestrogens less than 20 days preceding AI may negatively affect oocyte developmental competence, reduce progesterone production and thus contribute to early embryonic loss.

Investigation of luteal HCG supplementation in GnRH-agonist-triggered fresh embryo transfer cycles: a randomized controlled trial.

RESEARCH QUESTION: Does splitting the human chorionic gonadotrophin (HCG) support in IVF cycles triggered by a gonadotrophin-releasing hormone agonist result in a better progesterone profile? DESIGN: Randomized controlled three-arm study, performed at the Fertility Clinic, Odense University Hospital, Denmark. Patients with 12-25 follicles ≥12 mm were randomized into three groups: Group 1 - ovulation triggered with 6500 IU HCG; Group 2 - ovulation triggered with 0.5 mg GnRH agonist, followed by 1500 IU HCG on the day of oocyte retrieval (OCR); and Group 3 - ovulation triggered with 0.5 mg GnRH agonist, followed by 1000 IU HCG on the day of OCR and 500 IU HCG on OCR + 5. All groups received 180 mg vaginal progesterone. Progesterone concentrations were analysed in eight blood samples from each patient. RESULTS: Sixty-nine patients completed the study. Baseline and laboratory data were comparable. Progesterone concentration peaked on OCR + 4 in Groups 1 and 2, and peaked on OCR + 6 in Group 3. On OCR + 6, the progesterone concentration in Group 2 was significantly lower compared with Groups 1 and 3 (P = 0.003 and P < 0.001, respectively). On OCR + 8, the progesterone concentration in Group 3 was significantly higher compared with the other groups (both P<0.001). Progesterone concentrations were significantly higher in Group 3 from OCR + 6 until OCR + 14 compared with the other groups (all P ≤ 0.003). Four patients developed ovarian hyperstimulation syndrome in Group 3. CONCLUSION: Sequential HCG support after a GnRH agonist trigger provides a better progesterone concentration in the luteal phase.

Pathologic maternal and neonatal outcomes associated with programmed embryo transfer: potential etiologies and strategies for prevention.

PURPOSE: In the first of two companion papers, we comprehensively reviewed the recent evidence in the primary literature, which addressed the increased prevalence of hypertensive disorders of pregnancy, late-onset or term preeclampsia, fetal overgrowth, postterm birth, and placenta accreta in women conceiving by in vitro fertilization. The preponderance of evidence implicated frozen embryo transfer cycles and, specifically, those employing programmed endometrial preparations, in the higher risk for these adverse maternal and neonatal pregnancy outcomes. Based upon this critical appraisal of the primary literature, we formulate potential etiologies and suggest strategies for prevention in the second article. METHODS: Comprehensive review of primary literature. RESULTS: Presupposing significant overlap of these apparently diverse pathological pregnancy outcomes within subjects who conceive by programmed autologous FET cycles, shared etiologies may be at play. One plausible but clearly provocative explanation is that aberrant decidualization arising from suboptimal endometrial preparation causes greater than normal trophoblast invasion and myometrial spiral artery remodeling. Thus, overly robust placentation produces larger placentas and fetuses that, in turn, lead to overcrowding of villi within the confines of the uterine cavity which encroach upon intervillous spaces precipitating placental ischemia, oxidative and syncytiotrophoblast stress, and, ultimately, late-onset or term preeclampsia. The absence of circulating corpus luteal factors like relaxin in most programmed cycles might further compromise decidualization and exacerbate the maternal endothelial response to deleterious circulating placental products like soluble fms-like tyrosine kinase-1 that mediate disease manifestations. An alternative, but not mutually exclusive, determinant might be a thinner endometrium frequently associated with programmed endometrial preparations, which could conspire with dysregulated decidualization to elicit greater than normal trophoblast invasion and myometrial spiral artery remodeling. In extreme cases, placenta accreta could conceivably arise. Though lower uterine artery resistance and pulsatility indices observed during early pregnancy in programmed embryo transfer cycles are consistent with this initiating event, quantitative analyses of trophoblast invasion and myometrial spiral artery remodeling required to validate the hypothesis have not yet been conducted. CONCLUSIONS: Endometrial preparation that is not optimal, absent circulating corpus luteal factors, or a combination thereof are attractive etiologies; however, the requisite investigations to prove them have yet to be undertaken. Presuming that in ongoing RCTs, some or all adverse pregnancy outcomes associated with programmed autologous FET are circumvented or mitigated by employing natural or stimulated cycles instead, then for women who can conceive using these regimens, they would be preferable. For the 15% or so of women who require programmed FET, additional research as suggested in this review is needed to elucidate the responsible mechanisms and develop preventative strategies.

Enhancement of progesterone biosynthesis via kisspeptin stimulation: Upregulation of steroidogenic transcripts and phosphorylated extracellular signal-regulated kinase (p-ERK1/2) expression in the buffalo luteal cells.

The presence of Kisspeptin (Kp) and its receptors in the corpus luteum (CL) of buffalo has recently been demonstrated. In this study, we investigated the role of Kp in the modulation of progesterone (P4) synthesis in vitro. The primary culture of bubaline luteal cells (LCs) was treated with 10, 50, and 100 nM of Kp and Kp antagonist (KpA) alongside a vehicle control. The combined effect of Kp and KpA was assessed at 100 nM concentration. Intracellular response to Kp treatment in the LCs was assessed by examining transcript profiles (LHR, STAR, CYP11A1, HSD3B1, and ERK1/2) using quantitative polymerase chain reaction (qPCR). In addition, the immunolocalization of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the LCs was studied using immunocytochemistry. Accumulation of P4 from the culture supernatant was determined using enzyme-linked immunosorbent assay (ELISA). The results indicated that LCs had a greater p-ERK1/2 expression in the Kp treatment groups. A significant increase in the P4 concentration was recorded at 50 nM and 100 nM Kp, while KpA did not affect the basal concentration of P4. However, the addition of KpA to the Kp-treated group at 100 nM concentration suppressed the Kp-induced P4 accumulation into a concentration similar to the control. There was significant upregulation of ERK1/2 and CYP11A1 expressions in the Kp-treated LCs at 100 nM (18.1 and 37fold, respectively, p < 0.01). However, the addition of KpA to Kp-treated LCs modulated ERK1/2, LHR, STAR, CYP11A1, and HSD3B1 at 100 nM concentration. It can be concluded that Kp at 100 nM stimulated P4 production, while the addition of KpA suppressed Kp-induced P4 production in the buffalo LCs culture. Furthermore, an increment in p-ERK1/2 expression in the LCs indicated activation of the Kp signaling pathway was associated with luteal steroidogenesis.

Visfatin Affects the Transcriptome of Porcine Luteal Cells during Early Pregnancy.

Visfatin/NAMPT (VIS), the hormone exerting a pleiotropic effect, is also perceived as an important factor in the regulation of reproductive processes and pregnancy maintenance. Previous studies confirmed its involvement in the control of porcine pituitary and ovary function. In this study, we hypothesized that VIS may affect the global transcriptome of luteal cells and thus regulate the functioning of the ovaries. Illumina's NovaSeq 6000 RNA sequencing was performed to investigate the differentially expressed genes (DEGs) and long non-coding RNAs (DELs) as well as the occurrence of differential alternative splicing events (DASs) in the porcine luteal cells exposed to VIS (100 ng/mL) during the implantation period. The obtained results revealed 170 DEGs (99 up- and 71 downregulated) assigned to 45 functional annotations. Moreover, we revealed 40 DELs, of which 3 were known and 37 were described for the first time. We identified 169 DASs events. The obtained results confirmed a significant effect of VIS on the transcriptome and spliceosome of luteal cells, including the genes involved in the processes crucial for successful implantation and pregnancy maintenance as angiogenesis, steroidogenesis, inflammation, cell development, migration, and proliferation.

Bovine FRAS1: mRNA Expression Profile, Genetic Variations, and Significant Correlations with Ovarian Morphological Traits, Mature Follicle, and Corpus Luteum.

The amelioration of bovine fertility caused by a multi-factorial problem has always been a hot topic, among which the detection of available target genes is the most crucial. It was hypothesized that the Fraser extracellular matrix complex subunit 1 (FRAS1) gene detected by GWAS is involved in physiological activities such as ovarian development. Herein, unilateral ovaries from 2111 cows were used to examine the mRNA expression profile and polymorphisms of bovine FRAS1 and their associations with fertility-related characteristics. Firstly, it was confirmed that FRAS1 gene transcripts are expressed in various bovine tissues. Then, among five potential insertion-deletion (indel) loci, the 20 bp (named P3-D20-bp) and 15 bp (P4-D15-bp) deletion mutations were confirmed to be polymorphic with linkage equilibrium. Secondly, the P3-D20-bp polymorphism was significantly associated with ovarian weight and corpus luteum diameter in the metaestrus phase and ovarian length in the dioestrum stage. Additionally, both ovarian length and mature follicle diameter in metaestrus are significantly correlated with different genotypes of P4-D15-bp. Thirdly, the transcriptional expression of the FRAS1 gene in groups with a minimum value of ovarian weight or volume was significantly higher than the expression in groups with a maximum value. Instead of that, the more corpus luteum and mature follicles there are, the higher the transcription expression of the FRAS1 gene is. Furthermore, FRAS1 expression in cows with a heterozygous genotype (ID) of P3-D20-bp was significantly higher than others. Eventually, P3-D20-bp deletion could disturb the binding efficiency of WT1-I and Sox2 to FRAS1 sequence according to binding prediction, indicating that mutation may affect gene expression and traits by influencing the binding of transcription factors. Overall, the polymorphisms of P3-D20-bp and P4-D15-bp of the bovine FRAS1 gene significantly correlated to follicle or ovarian traits that could be applied in optimizing female fertility in cow MAS breeding programs.