Differential Effects of Oxytocin Receptor Antagonists, Atosiban and Nolasiban, on Oxytocin Receptor-Mediated Signaling in Human Amnion and Myometrium

Comparison of Intratympanic Oxytocin and Dexamethasone in Cisplatin Ototoxicity: An Experimental Study

Although it is widely used, there is still no valid treatment for ototoxicity caused by the antineoplastic drug cisplatin. In this study, we aimed to investigate the efficacy of intratympanic resveratrol and intratympanic dexamethasone treatment in cisplatin-induced ototoxicity. We also compared intratympanic atosiban (oxytocin antagonist) and oxytocin in cisplatin ototoxicity. In this study, 30 rats (60 ears) were used by separating into 5 groups. Cisplatin, oxytocin, dexamethasone, atosiban and 0.9% NaCl were administered intraperitoneally to all groups separately. Auditory Brainstem Response and Distortion Product Otoacoustic Emission tests were performed on all groups before and 72 h after the procedure. Pre-treatment values were higher than post-treatment values in all groups (p < 0.001). There was no significant prolongation of the post-treatment Auditory Brainstem Response I-IV interval in the oxytocin and dexamethasone groups (p > 0.05). There was no significant decrease in the frequencies of 2832 and 4004 after treatment in the oxytocin and dexamethasone group compared to pre-treatment in Distortion Product Otoacoustic Emission. As a result, it has been shown that intratympanic oxytocin may be an option that can be used in the treatment, although it is not as effective as dexamethasone in preventing cisplatin ototoxicity.

Bryophyllum pinnatum Inhibits Oxytocin and Vasopressin Signaling in Myometrial Cells

The medicinal plant Bryophyllum pinnatum was previously shown to block oxytocin (OT)-induced signals in myometrial cells, consistent with its tocolytic effect observed in patients. OT activates not only OT receptors but also V1A receptors, two receptors with high receptor homology that are both expressed in the myometrium and play a crucial role in myometrial contraction signaling. We aimed to study the molecular pharmacology of B. pinnatum herbal preparations using specific receptor ligands, the human myometrial cell line hTERT-C3, and cell lines expressing recombinant human OT and V1A receptors.We found that press juice from B. pinnatum (BPJ) inhibits both OT- and vasopressin (AVP)-induced intracellular calcium increases in hTERT-C3 myometrial cells. In additional assays performed with cells expressing recombinant receptors, BPJ also inhibited OT and V1A receptor-mediated signals with a similar potency (IC50 about 0.5 mg/mL). We further studied endogenous OT- and AVP-sensitive receptors in hTERT-C3 cells and found that OT and AVP stimulated those receptors with similar potency (EC50 of ~ 1 nM), suggesting expression of both receptor subtypes. This interpretation was corroborated by the antagonist potencies of atosiban and relcovaptan that we found. However, using qPCR, we almost exclusively found expression of OT receptors suggesting a pharmacological difference between recombinant OT receptors and native receptors expressed in hTERT-C3 cells.In conclusion, we show that B. pinnatum inhibits both OT and AVP signaling, which may point beyond its tocolytic effects to other indications involving a disbalance in the vasopressinergic system.

Transcriptomic analysis of the human placenta reveals trophoblast dysfunction and augmented Wnt signalling associated with spontaneous preterm birth

Preterm birth (PTB) is the leading cause of death in under-five children. Worldwide, annually, over 15 million babies are born preterm and 1 million of them die. The triggers and mechanisms of spontaneous PTB remain largely unknown. Most current therapies are ineffective and there is a paucity of reliable predictive biomarkers. Understanding the molecular mechanisms of spontaneous PTB is crucial for developing better diagnostics and therapeutics. To address this need, we conducted RNA-seq transcriptomic analysis, qRT-PCR and ELISA on fresh placental villous tissue from 20 spontaneous preterm and 20 spontaneous term deliveries, to identify genes and signalling pathways involved in the pathogenesis of PTB. Our differential gene expression, gene ontology and pathway analysis revealed several dysregulated genes (including OCLN, OPTN, KRT7, WNT7A, RSPO4, BAMBI, NFATC4, SLC6A13, SLC6A17, SLC26A8 and KLF8) associated with altered trophoblast functions. We identified dysregulated Wnt, oxytocin and cellular senescence signalling pathways in preterm placentas, where augmented Wnt signalling could play a pivotal role in the pathogenesis of PTB due to its diverse biological functions. We also reported two novel targets (ITPR2 and MYLK2) in the oxytocin signalling pathways for further study. Through bioinformatics analysis on DEGs, we identified four key miRNAs, - miR-524-5p, miR-520d-5p, miR-15a-5p and miR-424-5p - which were significantly downregulated in preterm placentas. These miRNAs may have regulatory roles in the aberrant gene expressions that we have observed in preterm placentas. We provide fresh molecular insight into the pathogenesis of spontaneous PTB which may drive further studies to develop new predictive biomarkers and therapeutics.

Is oxytocin receptor antagonist administration around embryo transfer associated with IVF treatment success? A systematic review and meta-analysis

A systematic literature review and meta-analysis was conducted to evaluate whether the administration of an oxytocin receptor antagonist (OTR-a) around embryo transfer is associated with live birth and pregnancy achievement in IVF treatment. Multiple databases were searched for randomized controlled trials (RCT) comparing the outcome of IVF treatment with administration of an OTR-a before, during or after embryo transfer versus administration of placebo/nil. The literature search identified 11 eligible RCT. The active compound was intravenous atosiban (n = 7), subcutaneous barusiban (n = 1) and oral nolasiban (n = 3). Clinical pregnancy rate was significantly higher in women receiving an OTR-a around embryo transfer (relative risk [RR] 1.31, 95% confidence interval [CI] 1.13-1.51, P = 0.0002, I² = 61%, n = 11 studies, n = 3611); however, live birth rate was not statistically significantly affected (RR 1.09, 95% CI 0.98-1.20, P = 0.11, I² = 25%, n = 5 studies, n = 2765). A sensitivity analysis on low risk of bias studies likewise indicates a higher clinical pregnancy chance (RR 1.11, 95% CI 1.01-1.22, P = 0.03, I² = 5%, n = 5 RCT, n = 2765). OTR-a administration in IVF treatment has the potential to increase IVF efficacy, although the treatment effects observed so far are small and have not been sufficiently corroborated.

Effects of atosiban on uterine peristalsis following frozen embryo transfer: A randomized controlled trial

OBJECTIVES

To compare the effects of atosiban (oxytocin antagonist) on uterine peristalsis and pregnancy outcomes in the frozen embryo transfer (FET) cycle.

SETTING

Srinagarind Hospital, a university hospital, Khon Kaen, Thailand.

DESIGN

A randomized, double-blinded, controlled trial.

METHODS

Fifty infertile women were randomized into the atosiban (n = 25) and placebo group (n = 25). Women in the study group received intravenous atosiban 6.75 mg, 30 min before embryo transfer, and continued infusion at 18 mg/h for 1 h. The dose was reduced to 6 mg/h for another 2 h. Saline solution was applied in the placebo group. The uterine peristalsis frequency was measured by transvaginal ultrasound 30 min before and 3 h after the embryo transfer.

RESULTS

The respective mean baseline uterine peristalsis frequency (time) in the atosiban and placebo group was 10.3 ± 2.4 and 9.2 ± 3.4. The respective duration of uterine peristalsis in the atosiban and placebo group after receiving the intervention was reduced to 7.9 ± 2.1 and 6.9 ± 2.7. The implantation rate and clinical pregnancy rate were not statistically significant different between atosiban group and placebo group (37.5% versus 31.0%, RR 1.21, 95%CI: 0.60-2.44 and 44% versus 36%, RR 1.22, 95%CI: 0.62-2.42, respectively). Subgroup analysis indicated that the clinical pregnancy rate in those >35 years of age was not significantly different between both groups (31.6% and 18.8 %, RR 1.68, 95%CI: 0.50-5.68).

CONCLUSION

Adding atosiban in FET did not reduce uterine peristalsis but may benefit the advanced age group.

Effect of the oxytocin receptor antagonist nolasiban on pregnancy rates in women undergoing embryo transfer following IVF: analysis of three randomised clinical trials

STUDY QUESTION

Does a single oral dose of nolasiban 900 mg administered 4 h before embryo transfer (ET) increase pregnancy rates in women undergoing IVF?

SUMMARY ANSWER

In an individual patient data (IPD) meta-analysis of three clinical trials, a single oral dose of nolasiban 900 mg was associated with an increased ongoing pregnancy rate of an absolute 5% (relative 15%).

WHAT IS KNOWN ALREADY

Several clinical studies have shown that blocking activation of oxytocin receptors by an oxytocin receptor (OTR) antagonist has the potential to decrease uterine contractions, increase endometrial perfusion and enhance endometrial decidualisation and other parameters of endometrial receptivity. It has been hypothesised that antagonism of oxytocin receptors could improve the likelihood of successful embryo implantation and thus increase pregnancy and live birth rates following ET.

STUDY DESIGN, SIZE, DURATION

This is an analysis of three randomised, double-blind, placebo-controlled trials, which randomised 1836 subjects between 2015 and 2019. We describe the results of a meta-analysis of individual participant data (IPD) from all three trials and the pre-specified analyses of each individual trial.

PARTICIPANT/MATERIAL, SETTING, METHODS

Participants were patients undergoing ET following IVF/ICSI in 60 fertility centres in 11 European countries. Study subjects were below 38 years old and had no more than one previously failed cycle. They were randomised to a single oral dose of nolasiban 900 mg (n = 846) or placebo (n = 864). In IMPLANT 1, additional participants were also randomised to nolasiban 100 mg (n = 62) or 300 mg (n = 60). Fresh ET of one good quality embryo (except in IMPLANT 1 where transfer of two embryos was allowed) was performed on Day 3 or Day 5 after oocyte retrieval, approximately 4 h after receiving the study treatment. Serum hCG levels were collected at 14 days post oocyte retrieval (Week 2) and for women with a positive hCG result, ultrasound was performed at Week 6 post-ET (clinical pregnancy) and at Week 10 post-ET (ongoing pregnancy). Pregnant patients were followed for maternal (adverse events), obstetric (live birth, gestational age at delivery, type of delivery, incidence of twins) and neonatal (sex, weight, height, head circumference, Apgar scores, congenital anomalies, breast feeding, admission to intensive care and specific morbidities e.g. jaundice, respiratory distress syndrome) outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

In an IPD meta-analysis of the clinical trials, a single oral dose of nolasiban 900 mg was associated with an absolute increase of 5.0% (95% CI 0.5, 9.6) in ongoing pregnancy rate and a corresponding increase of 4.4% (95% CI -0.10, 8.93) in live birth rate compared to placebo. Similar magnitude increases were observed for D3 or D5 transfers but were not significantly different from the placebo. Population pharmacokinetics (PK) demonstrated a correlation between higher exposures and pregnancy.

LIMITATIONS, REASON FOR CAUTION

The meta-analysis was not a pre-specified analysis. While the individual trials did not show a consistent significant effect, they were not powered based on an absolute increase of 5% in ongoing pregnancy rate. Only a single dose of up to 900 mg nolasiban was administered in the clinical trials; higher doses or extended regimens have not been tested. Only fresh ET has been assessed in the clinical trials to date.

WIDER IMPLICATIONS OF THE FINDINGS

The finding support the hypothesis that oxytocin receptor antagonism at the time of ET can increase pregnancy rates following IVF. The overall clinical and population PK data support future evaluation of higher doses and/or alternate regimens of nolasiban in women undergoing ET following IVF.

STUDY FUNDING/COMPETING INTERESTS

The trials were designed, conducted and funded by ObsEva SA. A.H., O.P., E.G., E.L. are employees and stockholders of ObsEva SA. E.L. is a board member of ObsEva SA. G.G. reports honoraria and/or non-financial support from ObsEva, Merck, MSD, Ferring, Abbott, Gedeon-Richter, Theramex, Guerbet, Finox, Biosilu, Preglem and ReprodWissen GmbH. C.B. reports grants and honoraria from ObsEva, Ferring, Abbott, Gedeon Richter and MSD. P.P. reports consulting fees from ObsEva. H.T. reports grants and or fees from ObsEva, Research Fund of Flanders, Cook, MSD, Roche, Gedeon Richter, Abbott, Theramex and Ferring. H.V. reports grants from ObsEva and non-financial support from Ferring. P.T. is an employee of Cytel Inc., who provides statistical services to ObsEva. J.D. reports consulting fees and other payments from ObsEva and, Scientific Advisory Board membership of ObsEva.

TRIAL REGISTRATION NUMBERS

ClinicalTrials.gov: NCT02310802, NCT03081208, NCT03758885.

TRIAL REGISTRATION DATES

December 2014 (NCT02310802), March 2017 (NCT03081208), November 2018 (NCT03758885).

FIRST PATIENT’S ENROLMENT

January 2015 (NCT02310802), March 2017 (NCT03081208), November 2018 (NCT03758885).

Uterine contractions in rodent models and humans

Aberrant uterine contractions can lead to preterm birth and other labour complications and are a significant cause of maternal morbidity and mortality. To investigate the mechanisms underlying dysfunctional uterine contractions, researchers have used experimentally tractable small animal models. However, biological differences between humans and rodents change how researchers select their animal model and interpret their results. Here, we provide a general review of studies of uterine excitation and contractions in mice, rats, guinea pigs, and humans, in an effort to introduce new researchers to the field and help in the design and interpretation of experiments in rodent models.

Confirmation of the cardiac safety of nolasiban in a randomised cohort of healthy female volunteers

Nolasiban is an orally active oxytocin receptor antagonist being developed to increase the efficiency of assisted reproductive technologies. This study evaluated the pharmacokinetics, pharmacodynamics, and cardiac safety of nolasiban in 45 healthy women of child-bearing age. Nolasiban was administered in a fasted state with a standardised lunch served 4.5 h post-dose. Concentration-effect modelling was used to assess the effect of two dosages of nolasiban (900 mg and 1800 mg) on QTc following single-dose administration. We found no significant change in QTc at all tested dosages. Two-sided 90% confidence intervals of geometric mean C_max for estimated QTc effects of nolasiban were below the threshold of regulatory concern. The sensitivity of the assay to detect small changes in QTc was confirmed by a significant shortening of QTc between 2 and 4 h after consumption of a meal, which served to validate the model. Independent of the nolasiban assessment, this study also explored the effects of sex hormones on ECG parameters, especially QT subintervals. We found a significant relationship between JTpc and oestradiol. Heart rate was negatively correlated with progesterone. This study confirms the cardiovascular safety of nolasiban and describes relationships of sex hormones and ECG parameters.

The mechanism of action of oxytocin antagonist nolasiban in ART in healthy female volunteers

RESEARCH QUESTION

What are the effects of the oxytocin receptor (OTR) antagonist nolasiban on uterine contractions, endometrial perfusion and endometrial mRNA expression?

DESIGN

Randomized, double-blind, parallel-group, mechanism-of-action study with nolasiban. Forty-five healthy, pre-menopausal women were treated with placebo, 900 mg or 1800 mg nolasiban on the day corresponding to blastocyst transfer. Ultrasonographic uterine contraction frequency and endometrial perfusion were assessed, and endometrial biopsies analysed by next-generation sequencing.

RESULTS

Both doses of nolasiban showed decreased contraction frequency and increased endometrial perfusion depending on the time point assessed. At 1800 mg, 10 endometrial genes (DPP4, CNTNAP3, CNTN4, CXCL12, TNXB, CTSE, OLFM4, KRT5, KRT6A, IDO2) were significantly differentially expressed (adjusted P < 0.05). Of these, OLFM4, DPP4 and CXCL12 were regulated in the same direction as genes involved in implantation during the window of implantation. In addition, three genes (DPP4, CXCL12 and IDO2) were associated with decidualization and endometrial receptivity.

CONCLUSIONS

These data expand our knowledge of the mechanism of action of nolasiban in increasing pregnancy rates after embryo transfer. The results suggest more marked effects of nolasiban 1800 mg compared with the 900 mg dose, supporting testing at higher doses in IVF patients.

Differential Expression of Circular RNAs in Polytocous and Monotocous Uterus during the Reproductive Cycle of Sheep

Simple Summary

The uterus is an important reproductive organ that provides nutrition and place for embryonic development. In this study, we identified circular RNAs by deep sequencing and analyzed their expression in the uteri of polytocous and monotocous sheep (FecB++) during follicular and luteal phases. Gene Ontology (GO) and KEGG enrichment analyses revealed that the source genes of these differential circular RNAs (circRNAs) were mainly enriched in reproductive hormone- and energy metabolism-related pathways. These results provide information on the molecular mechanisms of sheep prolificacy.

Abstract

CircRNA plays important roles in cell proliferation, differentiation, autophagy and apoptosis during development. However, there are few reports on circRNAs related to livestock reproduction. In this study, we identified circRNAs by deep sequencing and analyzed their expression in the uteri of polytocous and monotocous sheep (FecB++) during follicular and luteal phases. There were 147 and 364 circRNAs with differential expression in the follicular and luteal phases, respectively. GO and KEGG enrichment analysis was performed for the host genes of the circRNAs to predict the functions of differentially expressed circRNAs. These source genes were mainly involved in the estrogen signaling pathway, TGFβ signaling pathway, GnRH signaling pathway, oxytocin signaling pathway, pentose phosphate pathway, and starch and sucrose metabolism related to reproduction and energy metabolism. CircRNA expression patterns were validated by RT-qPCR. Our findings provide a solid foundation for the identification and characterization of key important circRNAs involved in reproduction.

Effects of exogenous oxytocin and atosiban antagonist on GABA in different region of brain

Gamma amino butyric acid (GABA) is the primary inhibitory neurotransmitter in the vertebral central nervous system. It functions by altering the membrane conductance of Cl- ions, maintaining the membrane potential close to the resting potential. The hormone oxytocin (OT) has a central action where it acts as a neuromodulatory peptide and exerts its action depending upon the distribution of OT receptors (OTR) in the target site. OTRs are G-protein-coupled receptors (GPCRs) comprising different subunits (Gq, Gi, and Gs). The G- protein isoforms have the ability to activate different pathways, but specific agonists and antagonists may show different affinities to OTRs, depending on the specific G-protein isoform to which they are coupled. It is well documented that OTR distribution varies with age and species and in regions of the brain. In this study, we attempted to observe the impact of OT and atosiban (OTA), an OT antagonist, on GABA levels in different regions of the brain. Study animals were exposed intraperitoneally (i.p.) to normal saline (0.89%), OT 0.0116 mg/kg, and OTA 1 mg/kg in different combinations, for 30days. It was observed that OT and OTA administration modulated GABA levels in different regions of brain, while normal saline had no effect. It may be due to OTR receptor expression in different regions of the brain. This is significant because region-specific expression of different receptors could be important in the development of new drugs targeting specific neuropsychiatric disorders.

Oxytocin Receptor Antagonists, Atosiban and Nolasiban, Inhibit Prostaglandin F2α-induced Contractions and Inflammatory Responses in Human Myometrium

Oxytocin receptor antagonists (OTR-A) have been developed as tocolytics for the management of preterm labour due to the significant role of oxytocin (OT) in the onset of both term and preterm labour. Similar to OT, prostaglandins (PGs) play key roles in myometrial contractility and cervical ripening. Inhibition of PG synthesis/activity is used to delay preterm birth. Thus, targeting the PG pathway in combination with an OTR-A may be an effective strategy for delaying preterm delivery. In this study, we examined the effects of atosiban and nolasiban on PGF_2α-induced contractions and pro-inflammatory responses in human pregnant myometrium. Both OTR-As, atosiban and nolasiban, inhibited PGF_2α-induced contractions in a dose-dependent manner (p < 0.001 and p < 0.01, respectively). These inhibitory effects involved the suppression of PGF_2α-mediated increase in intracellular calcium levels. In addition, the OTR-As significantly suppressed PGF_2α-induced activation of pro-inflammatory pathways such as NF-κB and mitogen activated protein kinases (MAPKs), and the subsequent expression of contraction-associated-protein, COX-2. We have demonstrated that atosiban and nolasiban not only inhibit contractions elicited by OT, but also inhibit contractions and inflammation induced by PGF_2α. This suggests a possible crosstalk between OTR and PG receptor signalling and highlights the importance of understanding G protein-coupled receptor interactions/crosstalk in the development of future tocolytics.

In silico profiling the interaction mechanism of 2,5-diketopiperazine derivatives as oxytocin antagonists

Oxytocin plays a vital role in the occurrence of preterm birth by interacting with oxytocin receptor (OTR), and thus OTR antagonists provide effective approaches for the treatment of early birth. Presently, for purpose of exploring the structural traits affecting the antagonism potency, the up-to-date largest set of 121 2,5-diketopiperazine derivatives as OTR antagonists was subjected to ligand-based three-dimensional quantitative structure-activity (3D-QSAR) analysis applying comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods. The resultant optimal CoMSIA model displays proper validity and predictability with cross-validated correlation coefficient Q² = 0.614, non-cross-validated correlation coefficient R²_ncv = 0.969 and predicted correlation coefficient R²_pre = 0.912 for the test set of compounds, respectively. In addition, docking study was carried out for further elucidating the binding modes of OTR antagonists. The final docking cavity was located among the TM2-TM7 helices of the target protein and proved to be the same as described by other scholars' researches of other type of OTR antagonists. The major amino acids forming the cavity are Q92, Q96, K116, Q119, V120, M123, G196, I201, Q295, W288, F311 and M315. Representative compound 118 forms two H-bonds with Q119 and two H-bonds with Q295, with also a π - π stacking effect with F311, respectively. Meanwhile, as a supplementary tool to study the antagonists' conformation in the binding cavity, molecular dynamics (MD) simulation was also performed to further elucidate the changes in the ligand-receptor complex. We hope that the obtained models and information may help to provide an insight into the interaction mechanism of OTR antagonists and facilitate the design and optimization of novel antagonists for preventing premature birth.

Oxidative Stress in Women Treated with Atosiban for Impending Preterm Birth

Preterm birth is defined as delivery before 37 completed weeks of pregnancy, and it is the leading cause of neonatal morbidity and mortality. Oxidative stress is recognized as an important factor in the pathogenesis of premature labor. We conducted this analysis to investigate the safety of administration of the tocolytic drug Atosiban—a reversible, competitive antagonist of the oxytocin receptor in the treatment of preterm birth and its impact on the level of oxidative stress in pregnant women after 48 hours of tocolytic treatment. This prospective study was conducted between March 2016 and August 2017 at the Obstetric Clinic of the Polish Mother's Memorial Hospital Research Institute. Total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) values as well as 3-nitrotyrosine, carbonyl, and thiol group levels were measured using an ELISA test in serum and plasma of 56 pregnant women before and after 48 hours of continuous administration of Atosiban. We found that TAS levels decreased almost twice after the 48-hour drug administration (0.936 ± 0.360 mmol/L vs. 0.582 ± 0.305 mmol/L, P < 0.001) while TOS increased from 18.217 ± 16.093 μmol/L to 30.442 ± 30.578 μmol/L (P < 0.001). We also found a significant increase in OSI index—almost a threefold increase from 0.022 ± 0.022 to 0.075 ± 0.085, P < 0.001. In addition, statistically significant differences in the level of carbonyl groups were found. It increased from 65.358 ± 31.332 μmol/L to 97.982 ± 38.047 μmol/L (P < 0.001), which indicates increased oxidation of plasma proteins. Furthermore, patients who gave birth prematurely had higher levels of TOS after a 48-hour drug administration than the second group with labor after 37 weeks of pregnancy (42.803 ± 34.683 μmol/L vs. 25.792 ± 27.821 μmol/L, P < 0.031). The obtained results clearly indicate that pregnant women during tocolytic treatment with Atosiban are in a state of increased oxidative stress and occurrence of preterm birth can be associated with this phenomenon. This trial is registered with NCT03570294.

Systematic review of p38 mitogen-activated kinase and its functional role in reproductive tissues

Oxidative stress (OS) plays a role in uterine tissue remodeling during pregnancy and parturition. While p38 MAPK is an OS-response kinase, a precise functional role is unknown. Therefore, we conducted a systematic review of literature on p38 MAPK expression, activation, and function in reproductive tissues throughout pregnancy and parturition, published between January 1980 and August 2017, using four electronic databases (Web of Science, PubMed, Medline, and CoCHRANE). We identified 418 reports; 108 were selected for full-text evaluation and 74 were included in final review. p38 MAPK was investigated using feto-maternal primary or immortalized cells, tissue explants, and animal models. Western blot was most commonly used to report phosphorylated (active) p38 MAPK. Human placenta (27), chorioamniotic membranes (14), myometrium (13), decidua (8), and cervix (1) were the studied tissues. p38 MAPK's functions were tissue and gestational age dependent. Isoform specificity was hardly reported. p38 MAPK activity was induced by ROS or proinflammatory cytokines to promote cell signaling linked to cell fate, primed uterus, ripened cervix, and proinflammatory cytokine/chemokine production. In 35 years, reports on p38 MAPK's role during pregnancy and parturition are scarce and current literature is insufficient to provide a comprehensive description of p38 MAPK's mechanistic role during pregnancy and parturition.

Serum oxytocin profiles in patients with repeated implantation failure during IVF cycles

OBJECTIVE

The objective of this study is to investigate the association between oxytocin (OT) levels and repeated implantation failure (RIF) during in vitro fertilization-embryo transfer (IVF-ET) cycles.

METHODS

Blood samples were collected from 108 women undergoing IVF-ET treatment at the following time points: gonadotrophin (Gn) administration day (Gn Day 0), hCG administration day (hCG Day 0), ET administration day (ET Day 0), and 5 d after ET (ET Day 5). Serum OT and steroid profiles were measured and compared among three groups: Group A included 38 women with a history of RIF, Group B included 41 women who became pregnant following the first fresh ET, and Group C included 29 women who did not become pregnant following the first fresh ET.

RESULTS

The OT levels of the three groups at different time points were not significantly different. Serum OT levels were significantly higher on hCG Day 0, ET Day 0, and ET Day 5 than on Gn Day 0, and they were significantly correlated with the estradiol concentration on ET Day 0.

CONCLUSIONS

RIF patients do not have elevated serum OT levels during IVF-ET cycles.

Oxytocin and cancer: An emerging link

The neuropeptide hormone oxytocin, which is released from the posterior pituitary gland, is involved in a number of physiological processes. Understanding of its effects is gradually increasing due to new research in this area. While mostly recognized as a reproductive system hormone, oxytocin also regulates other organ systems such as the brain and cardiovascular system. Recently, research has focused on unraveling its involvement in cancer, and emerging evidence suggests a potential role for oxytocin as a cancer biomarker. This review summarizes observations linking oxytocin and cancer, with a special emphasis on prostate cancer, where it may promote cell proliferation. Research suggests that oxytocin effects may depend on cell type, concentration of the hormone, its interactions with other hormones in the microenvironment, and the precise localization of its receptor on the cell membrane. Future research is needed to further elucidate the involvement of oxytocin in cancer, and whether it could be a clinical cancer biomarker or therapeutic target.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.