Proteomic studies of VEGFR2 in human placentas reveal protein associations with preeclampsia, diabetes, gravidity, and labor.

VEGFR2 (Vascular endothelial growth factor receptor 2) is a central regulator of placental angiogenesis. The study of the VEGFR2 proteome of chorionic villi at term revealed its partners MDMX (Double minute 4 protein) and PICALM (Phosphatidylinositol-binding clathrin assembly protein). Subsequently, the oxytocin receptor (OT-R) and vasopressin V1aR receptor were detected in MDMX and PICALM immunoprecipitations. Immunogold electron microscopy showed VEGFR2 on endothelial cell (EC) nuclei, mitochondria, and Hofbauer cells (HC), tissue-resident macrophages of the placenta. MDMX, PICALM, and V1aR were located on EC plasma membranes, nuclei, and HC nuclei. Unexpectedly, PICALM and OT-R were detected on EC projections into the fetal lumen and OT-R on 20-150 nm clusters therein, prompting the hypothesis that placental exosomes transport OT-R to the fetus and across the blood-brain barrier. Insights on gestational complications were gained by univariable and multivariable regression analyses associating preeclampsia with lower MDMX protein levels in membrane extracts of chorionic villi, and lower MDMX, PICALM, OT-R, and V1aR with spontaneous vaginal deliveries compared to cesarean deliveries before the onset of labor. We found select associations between higher MDMX, PICALM, OT-R protein levels and either gravidity, diabetes, BMI, maternal age, or neonatal weight, and correlations only between PICALM-OT-R (p < 2.7 × 10-8), PICALM-V1aR (p < 0.006), and OT-R-V1aR (p < 0.001). These results offer for exploration new partnerships in metabolic networks, tissue-resident immunity, and labor, notably for HC that predominantly express MDMX.

No impairment of contextual fear memory consolidation by oxytocin receptor antagonism in male rats.

Oxytocin is a peptide released into brain regions associated with the processing of aversive memory and threat responses. Given the expression of oxytocin receptors across this vigilance surveillance system of the brain, we investigated whether pharmacological antagonism of the receptor would impact contextual aversive conditioning and memory. Adult male rats were conditioned to form an aversive contextual memory. The effects of peripheral administration of either the competitive antagonist Atosiban or noncompetitive antagonist L-368,899 were compared to saline controls. Oxytocin receptor antagonism treatment did not significantly impact the consolidation of aversive contextual memory in any of the groups. We conclude that peripheral antagonism of oxytocin signalling did not impact the formation of aversive memory.

Validation of two immunoassays for oxytocin measurements in human saliva.

The objective of this research was to develop and validate two immunoassays for oxytocin measurement in human saliva, one using a monoclonal and the other a polyclonal antibody against oxytocin, whose affinity for oxytocin was tested by an antibody mapping epitope analysis. These assays were analytically validated and used to compare oxytocin concentrations with those obtained with a commercial kit before and after the extraction or reduction/alkylation (R/A) treatments to saliva samples. The assays were also used to evaluate changes in salivary oxytocin concentrations following a physical effort and an induced psychological stress, which have previously been described as situations that cause an increase in salivary oxytocin. Both assays showed to be precise and accurate in the validation studies, and the antibodies used showed a defined binding region in case of the monoclonal antibody, whereas the polyclonal antibody showed binding events through all the oxytocin sequence. Although the monoclonal and polyclonal assays showed a positive correlation, they give results in a different range of magnitude. Both assays showed significant increases in oxytocin concentrations when applied after the physical effort and the psychological stress. This study shows that a variability in the reported values of oxytocin can occur depending on the assay and indicates that the use of different types of antibodies can give a different range of values when measuring oxytocin in saliva.

An evolutionary timeline of the oxytocin signaling pathway.

Oxytocin is a neuropeptide associated with both psychological and somatic processes like parturition and social bonding. Although oxytocin homologs have been identified in many species, the evolutionary timeline of the entire oxytocin signaling gene pathway has yet to be described. Using protein sequence similarity searches, microsynteny, and phylostratigraphy, we assigned the genes supporting the oxytocin pathway to different phylostrata based on when we found they likely arose in evolution. We show that the majority (64%) of genes in the pathway are 'modern'. Most of the modern genes evolved around the emergence of vertebrates or jawed vertebrates (540 - 530 million years ago, 'mya'), including OXTR, OXT and CD38. Of those, 45% were under positive selection at some point during vertebrate evolution. We also found that 18% of the genes in the oxytocin pathway are 'ancient', meaning their emergence dates back to cellular organisms and opisthokonta (3500-1100 mya). The remaining genes (18%) that evolved after ancient and before modern genes were classified as 'medium-aged'. Functional analyses revealed that, in humans, medium-aged oxytocin pathway genes are highly expressed in contractile organs, while modern genes in the oxytocin pathway are primarily expressed in the brain and muscle tissue.

Exogenous oxytocin increases gaze to humans in male cats.

Although oxytocin (OT) plays a role in bonding between heterospecifics and conspecifics, the effects of OT on the formation of such interspecific social behavior have only been investigated between humans and dogs (Canis familiaris). In this study, for comparative evaluation of the effects of OT between dog-human and cat-human social interaction, we investigated the effects of exogenous OT on the behavior of domestic cats (Felis silvestris catus) toward humans. We intranasally administered OT or saline to 30 cats using a nebulizer and recorded their behavior (gaze, touch, vocalization, and proximity). The results showed an interaction between the administration condition and sex for gaze duration. Post hoc analyses revealed a significant increase in gaze in the OT condition in male cats but not in females. There were no significant differences in gaze toward owners and strangers in any condition or sex. The male-specific OT-mediated increase in gaze toward humans observed in this study differs from previous research on dogs wherein such effects were observed only in females. These findings suggest an overall effect of exogenous OT on cats' social relationship with humans as well as the possibility of different mechanisms between cat-human and dog-human relationships.

Continued versus discontinued oxytocin stimulation in the active phase of labour (CONDISOX): individual management based on artificial intelligence - a secondary analysis.

BACKGROUND: Current guidelines regarding oxytocin stimulation are not tailored to individuals as they are based on randomised controlled trials. The objective of the study was to develop an artificial intelligence (AI) model for individual prediction of the risk of caesarean delivery (CD) in women with a cervical dilatation of 6 cm after oxytocin stimulation for induced labour. The model included not only variables known when labour induction was initiated but also variables describing the course of the labour induction. METHODS: Secondary analysis of data from the CONDISOX randomised controlled trial of discontinued vs. continued oxytocin infusion in the active phase of induced labour. Extreme gradient boosting (XGBoost) software was used to build the prediction model. To explain the impact of the predictors, we calculated Shapley additive explanation (SHAP) values and present a summary SHAP plot. A force plot was used to explain specifics about an individual's predictors that result in a change of the individual's risk output value from the population-based risk. RESULTS: Among 1060 included women, 160 (15.1%) were delivered by CD. The XGBoost model found women who delivered vaginally were more likely to be parous, taller, to have a lower estimated birth weight, and to be stimulated with a lower amount of oxytocin. In 108 women (10% of 1060) the model favoured either continuation or discontinuation of oxytocin. For the remaining 90% of the women, the model found that continuation or discontinuation of oxytocin stimulation affected the risk difference of CD by less than 5% points. CONCLUSION: In women undergoing labour induction, this AI model based on a secondary analysis of data from the CONDISOX trial may help predict the risk of CD and assist the mother and clinician in individual tailored management of oxytocin stimulation after reaching 6 cm of cervical dilation.

Group differences in OXT methylation between patients with Major Depressive Disorder and healthy controls: A pre-registered replication study.

Depression is linked to stress which leaves traces in the epigenetic signature of genes. The oxytocin system is implicated in allostatic processes promoting adaption to environmental stressors. Interactions of the oxytocin system with the environment, e.g., methylation of the gene coding for oxytocin (OXT), are candidates for the investigation of the biological underpinnings of depression. Recently, we found hypomethylation of OXT in patients with Major Depressive Disorder (MDD) compared to healthy controls (HC). Since the replicability of findings is a key point of criticism in (epi­)genetic research, we aimed to confirm our previous findings in a pre-registered study (data was stored in a database prior to pre-registration) within a new sample of n = 85 patients with MDD and n = 85 HC. We investigated OXT DNA-methylation in peripheral blood samples, stressful life events and depression severity. In accordance with our previous study, we found hypomethylation of OXT in patients with MDD compared to HC. Methylation was not associated with stressful life events. Patients reported significantly more stressful life events compared to HC. Our study revealed that hypomethylation of OXT can be demonstrated in a reproducible fashion and provides further evidence for the involvement of the oxytocin system in depression.

Are there sex differences in oxytocin and vasopressin V1a receptors ligand binding affinities?

BACKGROUND: There is substantial evidence for sex differences in the functioning of one of the most common receptor systems; G protein-coupled receptors (GPCRs). There are many points along the GPCR-mediated molecular signaling pathway at which males and females may differ, one of the first of which, chronologically, is in the stability of the interaction between the ligand and the receptor, or its binding affinity. Here we investigate the binding affinities of oxytocin (OT) and vasopressin (AVP) at the oxytocin receptor (OTR) and the vasopressin V1a receptor (V1aR), both of which are present in numerous in brain regions associated with social behavior. METHOD: In order to investigate sex- and estrous cycle-dependent differences in ligand-receptor binding affinity, male (n = 6) Syrian hamsters (Mesocricetus auratus), females on the day of estrus (E females, n = 6), and females on the second day of diestrus (D2 females n = 6) were chosen for study. Brains from hamsters were mounted on slides and competition and saturation binding assays were conducted. RESULTS: We report a remarkable similarity in the binding affinities of OT and AVP in males and females. Small differences were detected, however, in receptor and ligand specificity in females depending on whether they were in the estrous or diestrous stage of their ovulatory cycle. CONCLUSION: These data suggest that sex differences in binding affinity are not a likely source of the many sex differences that have been observed in the effects of OT and AVP in hamsters and other species.

Patterns of neural activity in response to threatening faces are predictive of autistic traits: modulatory effects of oxytocin receptor genotype.

Autistic individuals generally demonstrate impaired emotion recognition but it is unclear whether effects are emotion-specific or influenced by oxytocin receptor (OXTR) genotype. Here we implemented a dimensional approach using an implicit emotion recognition task together with functional MRI in a large cohort of neurotypical adult participants (N = 255, male = 131, aged 17-29 years) to establish associations between autistic traits and neural and behavioral responses to specific face emotions, together with modulatory effects of OXTR genotype. A searchlight-based multivariate pattern analysis (MVPA) revealed an extensive network of frontal, basal ganglia, cingulate and limbic regions exhibiting significant predictability for autistic traits from patterns of responses to angry relative to neutral expression faces. Functional connectivity analyses revealed a genotype interaction (OXTR SNPs rs2254298, rs2268491) for coupling between the orbitofrontal cortex and mid-cingulate during angry expression processing, with a negative association between coupling and autistic traits in the risk-allele group and a positive one in the non-risk allele group. Overall, results indicate extensive emotion-specific associations primarily between patterns of neural responses to angry faces and autistic traits in regions processing motivation, reward and salience but not in early visual processing. Functional connections between these identified regions were not only associated with autistic traits but also influenced by OXTR genotype. Thus, altered patterns of neural responses to threatening faces may be a potential biomarker for autistic symptoms although modulatory influences of OXTR genotype need to be taken into account.

A dog's life: Early life histories influence methylation of glucocorticoid (NR3C1) and oxytocin (OXTR) receptor genes, cortisol levels, and attachment styles.

Early life deprivation and stress can contribute to life-long, problematic consequences, including epigenetic variations related to behavior and health. Domestic dogs share human environments and social-cognitive traits, making them a promising comparative model to examine developmental plasticity. We examined 47 owner-dog dyads, including dogs rescued from abusive or neglectful environments, and matched control dogs for changes in DNA methylation of glucocorticoid (NR3C1) and oxytocin (OXTR) receptor genes previously shown to be affected by early life stress in other species including humans. We used an attachment paradigm, which included a separation event to examine cortisol levels and owner-dog attachment styles. Overall, dogs with adverse histories had different NR3C1 methylation patterns as a function of age and less OXTR methylation than comparison dogs. Dogs with adverse histories did not differ in their cortisol change from baseline to poststressor from comparison dogs, but the change in cortisol was associated with NR3C1 methylation. In addition, dogs with a history of early life stress had more insecure attachment styles; for every unit increase of OXTR methylation, the odds increased for insecure attachment style. This study demonstrates that adverse life histories lead to methylation differences, resulting in the hypothalamic-pituitary-adrenal (HPA) axis's dysregulation and differences in behavioral phenotypes.

Impact of intrapartum oxytocin administration on neonatal sucking behavior and breastfeeding.

This study aimed to examine the effect of intrapartum oxytocin administration on neonatal sucking behavior and breastfeeding. A total of 64 pairs (29 in the group treated with intrapartum oxytocin and 35 in the control group) of normal infants within 24-48 h of birth and their mothers were recruited. Sucking ability was evaluated by measuring Non-Nutritive Sucking (NNS) for 5 min. Data on the rate of exclusive breastfeeding at 1 month postpartum were collected. In the adjusted multiple regression models, intrapartum oxytocin exposure was significantly associated with fewer total NNS bursts (95% confidence interval (CI), -7.02 to -0.22), longer pause times (95% CI, 1.33 to 10.21), and greater pause-time variability (95% CI, 3.63 to 63.92). Effects estimated using structural equation modeling revealed that intrapartum oxytocin exposure had a significant negative and direct effect on the practice of exclusive breastfeeding 1 month postpartum (ß = -0.238, p = 0.047). However, no NNS-mediated indirect effects were observed. This report demonstrates that infants born to mothers who receive intrapartum oxytocin may have impaired sucking ability for at least the first 48 h after birth, and breastfeeding support should be provided.

Oxytocin Modifies the Excitability and the Action Potential Shape of the Hippocampal CA1 GABAergic Interneurons.

Oxytocin (OT) is a neuropeptide that modulates social-related behavior and cognition in the central nervous system of mammals. In the CA1 area of the hippocampus, the indirect effects of the OT on the pyramidal neurons and their role in information processing have been elucidated. However, limited data are available concerning the direct modulation exerted by OT on the CA1 interneurons (INs) expressing the oxytocin receptor (OTR). Here, we demonstrated that TGOT (Thr4,Gly7-oxytocin), a selective OTR agonist, affects not only the membrane potential and the firing frequency but also the neuronal excitability and the shape of the action potentials (APs) of these INs in mice. Furthermore, we constructed linear mixed-effects models (LMMs) to unravel the dependencies between the AP parameters and the firing frequency, also considering how TGOT can interact with them to strengthen or weaken these influences. Our analyses indicate that OT regulates the functionality of the CA1 GABAergic INs through different and independent mechanisms. Specifically, the increase in neuronal firing rate can be attributed to the depolarizing effect on the membrane potential and the related enhancement in cellular excitability by the peptide. In contrast, the significant changes in the AP shape are directly linked to oxytocinergic modulation. Importantly, these alterations in AP shape are not associated with the TGOT-induced increase in neuronal firing rate, being themselves critical for signal processing.

Postpartum Oxytocin Treatment via the Mother Reprograms Long-Term Behavioral Disorders Induced by Early Life Stress on the Plasma and Brain Metabolome in the Rat.

The rat model of perinatal stress (PRS), in which exposure of pregnant dams to restraint stress reduces maternal behavior, is characterized by a metabolic profile that is reminiscent of the "metabolic syndrome". We aimed to identify plasma metabolomic signatures linked to long-term programming induced by PRS in aged male rats. This study was conducted in the plasma and frontal cortex. We also investigated the reversal effect of postpartum carbetocin (Cbt) on these signatures, along with its impact on deficits in cognitive, social, and exploratory behavior. We found that PRS induced long-lasting changes in biomarkers of secondary bile acid metabolism in the plasma and glutathione metabolism in the frontal cortex. Cbt treatment demonstrated disease-dependent effects by reversing the metabolite alterations. The metabolomic signatures of PRS were associated with long-term cognitive and emotional alterations alongside endocrinological disturbances. Our findings represent the first evidence of how early life stress may alter the metabolomic profile in aged individuals, thereby increasing vulnerability to CNS disorders. This raises the intriguing prospect that the pharmacological activation of oxytocin receptors soon after delivery through the mother may rectify these alterations.

In vitro inhibition of uterine contractions using electrospun nanofibers loaded with nifedipine and ML7.

OBJECTIVE: To formulate a nanofiber-based controlled drug delivery system that could be effective in preventing uterine contractions and can be used for the treatment of preterm labor. PATIENTS AND METHODS: We utilized uterine tissue samples obtained from ten pregnant women who underwent cesarean section at term to investigate the effect of nanofibers on spontaneous and induced myometrial contractions. We prepared nifedipine and ML7-loaded nanofibers using the electrospinning method with Poly(D,L-lactide-co-glycolide) (PLGA) polymer, resulted in seven groups of nanofibers, including a control group. Group I served as the control, Group II was non-drug loaded nanofiber, Group III was nifedipine (10-5 M) loaded nanofiber, Group IV was ML7 (3x10-5 M) loaded nanofiber, Group V was ML7 (3x10-5 M) and nifedipine (10-5 M) nanofiber, Group VI was ML7 (3x10-5 M) and nifedipine (3x10-5 M) nanofiber, and Group VII was ML7 (3x10-5 M) and nifedipine (10-4 M) nanofiber. To evaluate the contractile response, the nanofibers loaded with different doses of ML7 and nifedipine were applied onto the tissue strips, and in vitro organ bath experiments were performed. Full-thickness uterine samples were cleared of the serosa and surrounding tissues, and eight strips (3x10 mm) were prepared from each sample. The seven different nanofiber formulations were gently placed and sutured onto the strips, with one strip always kept as the time control. We recorded spontaneous, KCl-induced, and stimulated cumulative oxytocin-induced contractions from all samples in all groups. After completing all experiments, the viability of the strips was checked, and weight measurement was recorded. RESULTS: The administration of drug-loaded polymers resulted in a significant decrease in both the frequency and intensity of spontaneous and induced contractions in all groups (p<0.01). No significant difference was observed between the control group and the non-drug-loaded nanofiber group in post hoc analysis (p=0.704). In terms of amplitude and frequency of contractions, the most significant decrease was observed in group VII at cumulative oxytocin doses compared to the control and non-drug-loaded nanofiber groups (p<0.05). Moreover, group VI also showed a significant decrease in contraction intensity and frequency compared to the control and non-drug-loaded nanofiber groups (p<0.05). While the use of nifedipine and/or ML7-loaded nanofibers decreased both intensity and frequency of contraction, this attenuation was not significant compared to the control and empty polymer groups. However, a more significant inhibition was observed when ML7 was used with nifedipine at doses of 3x10-5 M and 10-4 M. CONCLUSIONS: The results indicate that human uterine contractions can be inhibited using calcium channel blocker (nifedipine) and myosin light chain kinase inhibitor (ML7) loaded nanofibers in uterine tissue strips. These results strongly suggested the potential for the development of locally effective and safe controlled drug release systems to prevent premature birth.

Methods for the induction of labor: efficacy and safety.

This review assessed the efficacy and safety of pharmacologic agents (prostaglandins, oxytocin, mifepristone, hyaluronidase, and nitric oxide donors) and mechanical methods (single- and double-balloon catheters, laminaria, membrane stripping, and amniotomy) and those generally considered under the rubric of complementary medicine (castor oil, nipple stimulation, sexual intercourse, herbal medicine, and acupuncture). A substantial body of published reports, including 2 large network meta-analyses, support the safety and efficacy of misoprostol (PGE1) when used for cervical ripening and labor induction. Misoprostol administered vaginally at doses of 50 µg has the highest probability of achieving vaginal delivery within 24 hours. Regardless of dosing, route, and schedule of administration, when used for cervical ripening and labor induction, prostaglandin E2 seems to have similar efficacy in decreasing cesarean delivery rates. Globally, although oxytocin represents the most widely used pharmacologic agent for labor induction, its effectiveness is highly dependent on parity and cervical status. Oxytocin is more effective than expectant management in inducing labor, and the efficacy of oxytocin is enhanced when combined with amniotomy. However, prostaglandins administered vaginally or intracervically are more effective in inducing labor than oxytocin. A single 200-mg oral tablet of mifepristone seems to represent the lowest effective dose for cervical ripening. The bulk of the literature assessing relaxin suggests this agent has limited benefit when used for this indication. Although intracervical injection of hyaluronidase may cause cervical ripening, the need for intracervical administration has limited the use of this agent. Concerning the vaginal administration of nitric oxide donors, including isosorbide mononitrate, isosorbide, nitroglycerin, and sodium nitroprusside, the higher incidence of side effects with these agents has limited their use. A synthetic hygroscopic cervical dilator has been found to be effective for preinduction cervical ripening. Although a pharmacologic agent may be administered after the use of the synthetic hygroscopic dilator, in an attempt to reduce the interval to vaginal delivery, concomitant use of mechanical and pharmacologic methods is being explored. Combining the use of a single-balloon catheter with dinoprostone, misoprostol, or oxytocin enhances the efficacy of these pharmacologic agents in cervical ripening and labor induction. The efficacy of single- and double-balloon catheters in cervical ripening and labor induction seems similar. To date, the combination of misoprostol with an intracervical catheter seems to be the best approach when balancing delivery times with safety. Although complementary methods are occasionally used by patients, given the lack of data documenting their efficacy and safety, these methods are rarely used in hospital settings.

Differential changes in maternal proinflammatory IL6 plasmalevels as a putatively surrogate marker of candidacy andclinical utility during mid- and late pregnancy hyperglycemia:interventional impact of clinical pharmacist on maternal andneonatal outcomes in a randomized clinical trial / Cambios diferenciales en los niveles plasmáticos de IL6 proinflamatoria materna como un marcador supuestamente sustituto de candidatura y utilidad clínica durante la hiperglucemia a mitad y final del embarazo: impacto intervencionista del farmacéutico clínico en los resultados maternos y neonatales en un ensayo clínico aleatorizado

Background/methods: The impact of clinical pharmacist on undiagnosed pregnancy hyperglycemia (PHG) in mid- and late- pregnancy as a major preventable cause of maternal and neonatal (M/N) complications is investigated. This longitudinal randomized controlled study of changes in plasma levels of predictive/prognostic/diagnostic biomarkers of oxytocin, thrombospondin, MCP1, IL6, MIF, insulin and LAR and undesirable M/N pregnancy outcomes in women with/out PHG (pregnancy normoglycemia; PNG) following the implementation of clinical pharmacist interventions were investigated. Results: A total of 68 PHG (36 intervention vs. 32 non-intervention) vs. 21 PNG participants were enrolled at 20–28 weeks and followed up till delivery. BMI of intervention PHG (unlike non-intervention) was greater (p=0.036) compared to PNG’s. LAR and insulin, oxytocin, thrombospondin1, adiponectin and MCP1 plasma levels and their differences between 2nd and 3rd pregnancy trimesters lacked discrepancies in participants. Both PHG groups in mid pregnancy had substantially greater HbA1c %, FPG and IL6 levels vs. PNG, while PHG non-intervention’ leptin was greater than PNG’s. In late pregnancy, greater SBP, IL6 and MIF levels between either PHG groups vs. PNG’s were observed. Unlike PHG non-intervention and PNG; IL6 level in PHG intervention group decreased (-2.54±6.61; vs. non-intervention PHG’s 4.26±5.28; p<0.001 and vs. PNG’s 2.30±4.27; p=0.023). None of the assessed M/N outcomes was found of differential significance between any of the three study groups. Conclusions: Proinflammatory IL6 as a robust and generalizable cardiometabolic risk-based and related pharmacotherapy biomarker in mid and late hyperglycemic pregnancy with likely implications of novel therapeutic targets was delineated by clinical pharmacist interventions.(AU)

Binding Affinity, Selectivity, and Pharmacokinetics of the Oxytocin Receptor Antagonist L-368,899 in the Coyote (Canis latrans).

L-368,899 is a selective small-molecule oxytocin receptor (OXTR) antagonist originally developed in the 1990s to prevent preterm labor. Although its utility for that purpose was limited, L-368,899 is now one of the most commonly used drugs in animal research for the selective blockade of neural OXTR after peripheral delivery. A growing number of rodent and primate studies have used L-368,899 to evaluate whether certain behaviors are oxytocin dependent. These studies have improved our understanding of oxytocin's function in the brains of rodents and monkeys, but very little work has been done in other mammals, and only a single paper in macaques has provided any evidence that L-368,899 can be detected in the CNS after peripheral delivery. The current study sought to extend those findings in a novel species: coyotes ( Canis latrans ). Coyotes are ubiquitous North American canids that form long-term monogamous pair-bonds. Although monogamy is rare in rodents and primates, all wild canid species studied to date exhibit social monogamy. Coyotes are therefore an excellent model organism for the study of oxytocin and social bonds. Our goal was to determine whether L-368,899 is a viable candidate for future use in behavioral studies in coyotes. We used captive coyotes at the USDA National Wildlife Research Center's Predator Research Facility to evaluate the pharmacokinetics of L-368,899 in blood and CSF during a 90-min time course after intramuscular injection. We then characterized the binding affinity and selectivity of L-368,899 to coyote OXTR and the structurally similar vasopressin 1a receptor. We found that L-368,899 peaked in CSF at 15 to 30 min after intramuscular injection and slowly accumulated in blood. L-368,899 was 40 times more selective for OXTR than vasopressin 1a receptors and bound to the coyote OXTR with an affinity of 12 nM. These features of L-368,899 support its utility in future studies to probe the oxytocin system of coyotes.

Maternal oxytocin treatment at birth increases epigenetic age in male offspring.

Exogenous oxytocin (OT) is widely used to induce or augment labor with little understanding of the impact on offspring development. In rodent models, including the prairie vole (Microtus ochrogaster), it has been shown that oxytocin administered to mothers can affect the nervous system of the offspring with long lasting behavioral effects especially on sociality. Here, we examined the hypothesis that perinatal oxytocin exposure could have epigenetic and transcriptomic consequences. Prairie voles were exposed to exogenous oxytocin, through injections given to the mother just prior to birth, and were studied at the time of weaning. The outcome of this study revealed increased epigenetic age in oxytocin-exposed animals compared to the saline-exposed group. Oxytocin exposure led to 900 differentially methylated CpG sites (annotated to 589 genes), and 2 CpG sites (2 genes) remained significantly different after correction for multiple comparisons. Differentially methylated CpG sites were enriched in genes known to be involved in regulation of gene expression and neurodevelopment. Using RNA-sequencing we also found 217 nominally differentially expressed genes (p<0.05) in nucleus accumbens, a brain region involved in reward circuitry and social behavior; after corrections for multiple comparisons 6 genes remained significantly differentially expressed. Finally, we found that maternal oxytocin administration led to widespread alternative splicing in the nucleus accumbens. These results indicate that oxytocin exposure during birth may have long lasting epigenetic consequences. A need for further investigation of how oxytocin administration impacts development and behavior throughout the lifespan is supported by these outcomes.

Third stage of labor: evidence-based practice for prevention of adverse maternal and neonatal outcomes.

The third stage of labor is defined as the time period between delivery of the fetus through delivery of the placenta. During a normal third stage, uterine contractions lead to separation and expulsion of the placenta from the uterus. Postpartum hemorrhage is a relatively common complication of the third stage of labor. Strategies have been studied to mitigate the risk of postpartum hemorrhage, leading to the widespread implementation of active management of the third stage of labor. Initially, active management of the third stage of labor consisted of a bundle of interventions including administration of a uterotonic agent, early cord clamping, controlled cord traction, and external uterine massage. However, the effectiveness of these interventions as a bundle has been questioned, leading to abandonment of some components in recent years. Despite this, upon review of selected international guidelines, we found that the term "active management of the third stage of labor" was still used, but recommendations for and against individual interventions were variable and not necessarily supported by current evidence. In this review, we: (1) examine the physiology of the third stage of labor, (2) present evidence related to interventions that prevent postpartum hemorrhage and promote maternal and neonatal health, (3) review current global guidelines and recommendations for practice, and (4) propose future areas of investigation. The interventions in this review include pharmacologic agents to prevent postpartum hemorrhage, cord clamping, cord milking, cord traction, cord drainage, early skin-to-skin contact, and nipple stimulation. Treatment of complications of the third stage of labor is outside of the scope of this review. We conclude that current evidence supports the use of effective pharmacologic postpartum hemorrhage prophylaxis, delayed cord clamping, early skin-to-skin contact, and controlled cord traction at delivery when feasible. The most effective uterotonic regimens for preventing postpartum hemorrhage after vaginal delivery include oxytocin plus ergometrine; oxytocin plus misoprostol; or carbetocin. After cesarean delivery, carbetocin or oxytocin as a bolus are the most effective regimens. There is inconsistent evidence regarding the use of tranexamic acid in addition to a uterotonic compared with a uterotonic alone for postpartum hemorrhage prevention after all deliveries. Because of differences in patient comorbidities, costs, and availability of resources and staff, decisions to use specific prevention strategies are dependent on patient- and system-level factors. We recommend that the term "active management of the third stage of labor" as a combined intervention no longer be used. Instead, we recommend that "third stage care" be adopted, which promotes the implementation of evidence-based interventions that incorporate practices that are safe and beneficial for both the woman and neonate.

The physiology and pharmacology of oxytocin in labor and in the peripartum period.

Oxytocin is a reproductive hormone implicated in the process of parturition and widely used during labor. Oxytocin is produced within the supraoptic nucleus and paraventricular nucleus of the hypothalamus and released from the posterior pituitary lobe into the circulation. Oxytocin is released in pulses with increasing frequency and amplitude in the first and second stages of labor, with a few pulses released in the third stage of labor. During labor, the fetus exerts pressure on the cervix of the uterus, which activates a feedforward reflex-the Ferguson reflex-which releases oxytocin. When myometrial contractions activate sympathetic nerves, it decreases oxytocin release. When oxytocin binds to specific myometrial oxytocin receptors, it induces myometrial contractions. High levels of circulating estrogen at term make the receptors more sensitive. In addition, oxytocin stimulates prostaglandin synthesis and release in the decidua and chorioamniotic membranes by activating a specific type of oxytocin receptor. Prostaglandins contribute to cervical ripening and uterine contractility in labor. The oxytocin system in the brain has been implicated in decreasing maternal levels of fear, pain, and stress, and oxytocin release and function during labor are stimulated by a social support. Moreover, studies suggest, but have not yet proven, that labor may be associated with long-term, behavioral and physiological adaptations in the mother and infant, possibly involving epigenetic modulation of oxytocin production and release and the oxytocin receptor. In addition, infusions of synthetic oxytocin are used to induce and augment labor. Oxytocin may be administered according to different dose regimens at increasing rates from 1 to 3 mIU/min to a maximal rate of 36 mIU/min at 15- to 40-minute intervals. The total amount of synthetic oxytocin given during labor can be 5 to 10 IU, but lower and higher amounts of oxytocin may also be given. High-dose infusions of oxytocin may shorten the duration of labor by up to 2 hours compared with no infusion of oxytocin; however, it does not lower the frequency of cesarean delivery. When synthetic oxytocin is administered, the plasma concentration of oxytocin increases in a dose-dependent way: at infusion rates of 20 to 30 mIU/min, plasma oxytocin concentration increases approximately 2- to 3-fold above the basal level. Synthetic oxytocin administered at recommended dose levels is not likely to cross the placenta or maternal blood-brain barrier. Synthetic oxytocin should be administered with caution as high levels may induce tachystole and uterine overstimulation, with potentially negative consequences for the fetus and possibly the mother. Of note, 5 to 10 IU of synthetic oxytocin is often routinely given as an intravenous or intramuscular bolus administration after delivery to induce uterine contractility, which, in turn, induces uterine separation of the placenta and prevents postpartum hemorrhage. Furthermore, it promotes the expulsion of the placenta.