Maternal and newborn plasma oxytocin levels in response to maternal synthetic oxytocin administration during labour, birth and postpartum – a systematic review with implications for the function of the oxytocinergic system

BackgroundThe reproductive hormone oxytocin facilitates labour, birth and postpartum adaptations for women and newborns. Synthetic oxytocin is commonly given to induce or augment labour and to decrease postpartum bleeding.AimTo systematically review studies measuring plasma oxytocin levels in women and newborns following maternal administration of synthetic oxytocin during labour, birth and/or postpartum and to consider possible impacts on endogenous oxytocin and related systems.MethodsSystematic searches of PubMed, CINAHL, PsycInfo and Scopus databases followed PRISMA guidelines, including all peer-reviewed studies in languages understood by the authors. Thirty-five publications met inclusion criteria, including 1373 women and 148 newborns. Studies varied substantially in design and methodology, so classical meta-analysis was not possible. Therefore, results were categorized, analysed and summarised in text and tables.ResultsInfusions of synthetic oxytocin increased maternal plasma oxytocin levels dose-dependently; doubling the infusion rate approximately doubled oxytocin levels. Infusions below 10 milliunits per minute (mU/min) did not raise maternal oxytocin above the range observed in physiological labour. At high intrapartum infusion rates (up to 32 mU/min) maternal plasma oxytocin reached 2-3 times physiological levels.Postpartum synthetic oxytocin regimens used comparatively higher doses with shorter duration compared to labour, giving greater but transient maternal oxytocin elevations. Total postpartum dose was comparable to total intrapartum dose following vaginal birth, but post-caesarean dosages were higher.Newborn oxytocin levels were higher in the umbilical artery vs. umbilical vein, and both were higher than maternal plasma levels, implying substantial fetal oxytocin production in labour. Newborn oxytocin levels were not further elevated following maternal intrapartum synthetic oxytocin, suggesting that synthetic oxytocin at clinical doses does not cross from mother to fetus.ConclusionsSynthetic oxytocin infusion during labour increased maternal plasma oxytocin levels 2-3-fold at the highest doses and was not associated with neonatal plasma oxytocin elevations. Therefore, direct effects from synthetic oxytocin transfer to maternal brain or fetus are unlikely. However, infusions of synthetic oxytocin in labour change uterine contraction patterns. This may influence uterine blood flow and maternal autonomic nervous system activity, potentially harming the fetus and increasing maternal pain and stress

Metabolomic analysis of white and yellow seminal plasma in turkeys (Meleagris gallopavo)1

Numerous studies have indicated that yellow semen syndrome (YSS) of turkey is associated with the production of low semen quality, resulting in reduced fertility and hatchability. It is unknown at present if the etiology of YSS also could be linked to low-molecular weight metabolites. The aim of this study was to examine the metabolome of white and yellow seminal plasma of turkeys. Two different metabolomics approaches, shotgun (direct infusion) and liquid chromatography-mass spectrometry (LC-MS), were employed to identify metabolites differentially abundant in yellow seminal plasma. Significant changes in the levels of 1549 and 2093 metabolites were detected in yellow vs. white seminal plasma using shotgun and LC-MS, respectively. Of these, 354 metabolites (189 increased and 165 decreased) after shotgun and 936 metabolites (363 increased and 573 decreased) after LC-MS were putatively identified using the Human Metabolome Database. Significantly differentiated metabolites were subjected to Ingenuity Pathway Analysis. Lipid metabolism, molecular transport, and nucleic acid metabolism were the top pathways that differentiated white and yellow seminal plasma. These data strongly suggest that disturbance of carbohydrate and lipid metabolism is characteristic for YSS. The abnormal metabolism of lipids may contribute to the numerous lipid vacuoles previously observed in the reproductive tracts of YSS males. An increased level of riboflavin in YSS may be responsible for yellow turkey semen pigmentation. A disturbance in thyroid hormone metabolism visible at protein and metabolic levels may be involved in YSS in turkey. The low quality of YSS may be linked with the presence of drug residues in the reproductive tract. [Abstract copyright: © 2017 Poultry Science Association Inc.