The role of oxytocin in parturition

Abstract

Oxytocin and the oxytocin receptor have two important roles in labour. Evidence in all mammalian species suggests that neurohypophysical oxytocin plays a role in the expulsive phase and, although there are less supporting data, a role for oxytocin in the initiation of labour is likely. The initiation of labour may be mediated in women and rhesus monkeys by paracrine rather than endocrine mechanisms. Although initial characterisation of the oxytocin knockout mouse suggested that oxytocin is not important in this species, subsequent investigations have demonstrated that oxytocin is important for the precise timing of the onset of labour. Studies in knockout mice also confirm important interrelationships between oxytocin and prostaglandins. Oxytocin stimulates prostaglandin release in many species, mainly in the decidua/uterine epithelium. The effects of oxytocin are mediated by tissue-specific oxytocin receptor expression, which leads directly to contraction in the myometrium and prostaglandin formation in the decidua. There is a dramatic increase in oxytocin receptor expression in these tissues in late pregnancy and pharmacological inhibition delays delivery, which suggests that, in contrast to oxytocin, the oxytocin receptor is essential for normal labour.

Oxytocin is associated with infant-care behavior and motivation in cooperatively breeding marmoset monkeys

“…OT levels in the pre-partum week and early post-partum period were highest in female breeders, consistent with the general role of OT in parturition (Blanks and Thornton, 2003) and lactation (Uvnäs-Moberg et al, 2001). However, the post-partum OT increase in fathers and non-reproductive helpers suggests that the role of OT extends beyond maternal reproduction and is also linked to infant-care, in both parents and alloparents.…”

“…Its ancient functions in female reproduction, related to cervix and uterus distension during labor (Blanks and Thornton, 2003;Kendrick and Keverne, 1989;Landgraf et al, 1983;Nissen et al, 1995), milk injection during lactation (Uvnäs-Moberg et al, 2001), and the regulation of maternal behavior (Feldman, 2007;Kendrick, 2000;Kendrick et al, 1987;Pedersen et al, 1994;Uvnäs-Moberg, 1996), probably formed the basis for derived OT functions in non-maternal social contexts (Broad et al, 2006;Kendrick, 2000;Lim and Young, 2006). However, less is known about the role of OT in alloparental care, i.e.…”

“…Crockford et al (2014) review and discuss the relevance of peripheral OT measures for studying the dynamics of social interactions and relationships with particular emphasis on urinary OT. Besides its effects in social bonding and affiliation in mammals (Lim and Young, 2006), peripheral OT is involved in female reproduction (labor and milk letdown: Blanks and Thornton, 2003;Uvnäs-Moberg et al, 2001) and anxiety reduction (Olff et al, 2013). A broadening body of evidence indicates that these central and peripheral OT pathways can be coordinated (Carson et al, 2014;Carter et al, 2007;O'Byrne et al, 1990;Ross and Young, 2009;Wotjak et al, 1998) and may exert crosslinked effects (Ayers et al, 2011;Madden and Clutton-Brock, 2011;Witt et al, 1990).…”

High-risk pregnancy management in women with hypopituitarism

“…38 In the uterine smooth muscle oxytocin has a direct uterotonic effect, whereas in the choriodecidual tissue it releases prostaglandins PGE 2 and PGF 2a . 39 Membrane-bound oxytocin receptor (OT-R) transduces the oxytocin effect. 40 OT-R density within the myometrium increases towards term.…”

“…Accordingly, it has been postulated that oxytocin from different sources contributes to the various stages of labor, with uterine oxytocin supporting the initiation of parturition and pituitary oxytocin the expulsive phase. 39 In the postpartum course, pituitary oxytocin is involved in uterine involution, whereas the relevance of locally produced oxytocin in puerperium is unknown. Abbreviations: A, adenoma; AG, agalactosis; APH, antepartum hemorrhage; C, cortisone; CP, craniopharyngioma; CD, cesarean delivery; CDr, controlled drinking; D, desmopressin; ECD, emergency cesarean delivery; EP, estrogen-progestin combination; F, female; FSH, follicle stimulating hormone; G, germinoma; GA, gestational age; GH, growth hormone; GnRH, gonadotropin-releasing hormone; HCG, human chorionic gonadotropin; HMG, human menopausal gonadotropin; HPG, human pituitary gonadotropin; IOL, induction of labor; IUFD, intrauterine fetal demise; L, lymphocytic hypophysis; LA, lactation; L-T4, L-thyroxine; M, male; NR, not reported; NVD, normal vaginal delivery; P, prolactinoma; PIH, pregnancyinduced hypertension; PPH, postpartum hemorrhage; PROM, premature rupture of membranes; PTL, preterm labor; rS, recurrent surgery; Rx, radiotherapy; S, pituitary surgery; Sh, Sheehan's syndrome; T, tuberculoma; TAH, total abdominal hysterectomy; V, arg-vasopressin.…”