The substitution of glutamine by threonine in position 4 of oxytocin, deamino-oxytocin, deamino-1-carba-oxytocin, and deamino-6-carba-oxytocin was found to increase the elimination rate of all analogs examined from the uterine receptor compartment in rat. However, this substitution was without any effect on the time course of uterotonic response in the case of vasotocin and deamino-vasotocin. T...

Luteolysis in sheep is associated with uterine secretion of pulses of prostaglandin F2 alpha (PGF2 alpha) due to the action of luteal oxytocin on endometrial oxytocin receptors. For pregnancy to become established inhibition of oxytocin receptors is important as an antiluteolytic mechanism. The maternal recognition of pregnancy in cattle and sheep involves production, by the trophoblast, of a t...

BACKGROUND Oxytocin receptor desensitization has been shown to occur in humans at biomolecular level and in isolated rat myometrium; however, its effect on human myometrial contractility has not been demonstrated. The objective of this in vitro study was to investigate the contractile response of human pregnant myometrium to oxytocin after pretreatment with different concentrations of oxytocin ...

Administration of the dopamine receptor agonist apomorphine causes a dose-dependent increase in plasma oxytocin concentrations and dose-specific behavioral changes in rodents. To investigate whether dopamine receptor agonists will elicit similar neuroendocrine and behavioral effects in primates, we administered graded doses of apomorphine and the respective dopamine D1 and D2 receptor agonists,...

BACKGROUND It has been shown that the neurohypophyseal peptide oxytocin is present in the human thymus and in vitro it can mimic interleukin (IL)-2 action in the induction of interferon-gamma production. In the present study, we tested the capacity of oxytocin to modulate the response of peripheral blood mononuclear cells (PBMCs) to phytohemagglutinin (PHA) and its ability to change the membran...

Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the ins...

The aim of this study was to investigate the molecular changes associated with the transition of the human oxytocin receptor from its inactive to its active states. Mutation of the conserved arginine of the glutamate/aspartate-arginine-tyrosine motif located in the second intracellular domain gave rise to the first known constitutively active oxytocin receptor (R137A), whereas mutation of the a...

, fetal human oxytocin at birth is of fetal origin, because its concentrations are higher in the umbilical artery than in the umbilical vein, and oxytocin is completely absent in cord blood of anencephalic new-borns (Chard et al., 1971). Parturition is a very complex process and oxytocin has its role particularly in contractility of myocytes (Smith, 2007). Exogenous oxytocin administration to p...

Vasopressin and oxytocin are synthesised in the hypothalamus and released to the blood stream via the posterior lobe of the hypophysis. Research during later years has shown that these peptides are also produced in other parts of the brain. The secretion to plasma is stimulated by oestrogen, an effect which is counteracted by progestagen. During delivery the fetus can also produce substantial a...