Oxytocin Receptors and Human Parturition: A Dual Role for Oxytocin in the Initiation of Labor

Abstract

The concentration of oxytocin receptors increased in the myometrium of pregnant women and reached maximum levels in early labor. Concentrations of oxytocin receptors were also high in the decidua and reached a maximum at parturition. In vitro, prostaglandin production by the decidua, but not by the myometrium, was increased by the addition of oxytocin. Oxytocin may therefore stimulate uterine contractions by acting both directly on the myometrium and indirectly on decidual prostaglandin production. Oxytocin receptors are probably crucial for the onset of human labor, and the stimulus for the increase in uterine prostaglandins may be oxytocin originating from the fetus.

Advances in the role of oxytocin receptors in human parturition

“…This was first described in rats [13], and subsequently demonstrated in rabbits and humans [12,31]. In both species, OTRs are present in the endometrium as well as the myometrium, chorio-decidua and amnion [12,32]. This increase in OTR is one of the most consistent findings in the study of parturition in several species, which introduces the possibility that changes in the expression or the function of the OTRs are important for the onset of labour.…”

“…The key prolabour responses induced by OT are indistinguishable to that of normal spontaneous labour and OT is one of the strongest uterotonins available to stimulate uterine contractions for labour induction or augmentation. Moreover, there is significant increase in uterine sensitivity to OT via upregulation of OTR in both rats and humans during the onset of labour [12][13][14]. Additionally studies in rats [15][16][17], non-human primates [18][19][20] and in humans [21,22] reported that OT antagonists can inhibit late gestational uterine contractions and the process of parturition.…”

“…This is associated with an upregulation of OTR mRNA levels and a strong increase in the density of myometrial OTRs reaching a peak during early labour [30]. This was first described in rats [13], and subsequently demonstrated in rabbits and humans [12,31]. In both species, OTRs are present in the endometrium as well as the myometrium, chorio-decidua and amnion [12,32].…”

Common Oxytocin Receptor Gene Polymorphisms and the Risk for Preterm Birth

“…In the myometrium oxytocin activates phospholipase C, which increases the intracellular calcium concentration and thus intensifies uterine contractions. Mediated by activation of the OXTR, oxytocin additionally seems to assist cervical ripening by stimulating the synthesis of prostaglandins in the chorion, decidua, and amnion [7,12].…”

Avaliação hormonal sérica e estereológica da membrana corioalantóide a termo de éguas: influência no desenvolvimento e nos parâmetros clínicos e metabólicos do potro

“…Essas alterações são iniciadas pelo declínio dos progestágenos e aumento das concentrações de estradiol próximo ao termo (FUCHS et al, 1982).…”