Plasma Oxytocin Concentrations in Men, Nonpregnant Women, and Pregnant Women before and during Spontaneous Labor*

Leake, Rosemary D.; Weitzman, Richard E.; Glatz, Theodore H.; Fisher, Delbert A.

doi:10.1210/jcem-53-4-730

Cited by 153 publications

(71 citation statements)

References 20 publications

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“…2) found in this study are within the range of the low predelivery values found in most recent studies (Leake et al 1981, Fuchs et al 1991, Thornton et al 1992, OT plasma levels seem to rise only during delivery by an increase in pulse frequency and duration. Np-OT, measured in this study, was determined by subtraction assay and is considered to be an index of endogenous oestrogens (Legros & Grau 1973).…”

Section: Discussionsupporting

confidence: 90%

Vasopressin and oxytocin levels during normal pregnancy: effects of chronic dietary sodium restriction

Post

Buul²,

Hart³

et al. 1997

Journal of Endocrinology

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Neurohypophysial hormones are thought to be involved in alterations in fluid balance during pregnancy and delivery. In the course of normal pregnancy intravascular volume is increased whereas sodium restriction is thought to reduce plasma volume and cardiac output. In the present study, we measured the effect of long-term severe sodium restriction on vasopressin (AVP) and oxytocin (OT) levels during normal pregnancy and after delivery.Fifty-nine healthy nulliparous women were randomized either for a low sodium diet (20 mmol sodium daily) or for a normal diet from week 12 of pregnancy onwards, Circulating plasma levels and urinary excretion of AVP and OT, their neurophysins (Np-AVP and Np-OT) and AVP bound to platelets were determined at regular intervals during pregnancy and after delivery. After com pletion of the study, women on a sodium-restricted diet were compared with control women on a normal diet using repeated measurement ANOVA with adjustment for potentially confounding variables.After randomization, a reduction in urinary sodium excretion of, on average, 40-82% was found. In general, no effect of sodium restriction could be demonstrated on the various parameters (0*53< P < 0*98) with the exception of a significantly lower 24-h urinary AVP excretion by non-smokers with sodium restriction compared with non-smokers having a normal diet (P=0'018). For all parameters, clear changes were found in the course of pregnancy and puerperium (P<0*0001 to P<0'005). Platelet-bound AVP decreased and N p -O T increased during pregnancy. After birth, free plasma AVP, plateletbound AVP, O T, osmolality, sodium and potassium increased, while Np-AVP and N p -O T decreased.Although elevated Np-AVP and N p-O T levels during pregnancy seem to indicate increased release of neuro hypophysial hormones, pregnancy up to 36 weeks of gestation is accompanied by low circulating AVP and O T levels.Long-term severe sodium restriction diminishes urinary AVP excretion in (non-smoking) pregnant women, with out changing circulating levels of AVP and OT, despite the known reduction in circulating volume. The reduced circulating (plat el et-bound) AVP levels during pregnancy, whether or not in combination with severe sodium restriction, support the absence of significant non-osmotic stimulation of AVP during pregnancy.

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Section: Discussionsupporting

confidence: 90%

Vasopressin and oxytocin levels during normal pregnancy: effects of chronic dietary sodium restriction

Post

Buul²,

Hart³

et al. 1997

Journal of Endocrinology

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show abstract

“…Although in rodents, OT is believed to play a significant role in the initiation and maintenance of parturition [13,23], in humans, circulating OT does not seem to be essential for the initiation and maintenance of labour [24]. Normal parturition has been observed in the absence of OT in mice [24] as well as in cases of clinical pituitary gland dysfunction [25] and the concentrations of maternal or fetal OT does not increase with the onset of or during labour [26].…”

Section: Previously Established Roles Of Ot/otr Systemmentioning

confidence: 99%

Advances in the role of oxytocin receptors in human parturition

Kim

Bennett

Terzidou

2017

Molecular and Cellular Endocrinology

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“…Nevertheless, the pituitary may provide the source of oxytocin since a basal level of oxytocin was measurable in human serum throughout pregnancy (Leake et al 1981) and a low pulsatile secretion of oxytocin was also found in pregnant cows (Fuchs et al 1986).…”

Section: Figurementioning

confidence: 99%

Regulation of oxytocin receptor in the placentome capsule throughout pregnancy in the ewe: the possible role of oestradiol receptor, progesterone receptor and aromatase

Leung

Reynolds²,

Wathes³

1998

Journal of Endocrinology

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The hormonal regulation of uterine oxytocin receptors (OTR) during the establishment of pregnancy and at parturition has been studied extensively, but little information is available during mid-pregnancy. This study investigated the localisation of OTR mRNA in the ovine placentome throughout gestation and related this to expression patterns for the putative regulatory agents aromatase, oestradiol receptor, progesterone receptor and oxytocin. Placentomes were collected at regular intervals throughout pregnancy for in situ hybridisation analysis and immunocytochemistry (oestradiol receptor only). Results were quantified by optical density measurements of autoradiographs. Progesterone receptor mRNA was localised to the caruncular tissues on day 30 but became undetectable by day 34. Aromatase mRNA appeared in the fetal villi at days 34-40, with concentrations peaking at days 52-55 and again at days 132-137. Oestradiol receptor mRNA was localised to the caruncular tissues from days 13 to 30 and found in the maternal villi and placentome capsule from days 45 to 70. Oestradiol receptor protein was barely detectable in either tissue. OTR mRNA was localised to the placentome capsule at days 34-40, remaining high at day 45 and declining to basal levels by days 132-137. Oxytocin mRNA was not detected in the placentome. In conclusion: (1) progesterone acting via its receptor may suppress the expression of aromatase and OTR in early pregnancy; (2) the up-regulation of OTR expression in the capsule may not involve the oestradiol receptor; (3) there is a differential regulation between different regions of the uterus as the increase in the placentome capsule occurs at a time when concentrations in the rest of the endometrium and myometrium remain low; (4) oestradiol receptor expression in the placentome may be regulated at the translational level; and (5) there is no local production of oxytocin in the sheep placenta. The role of OTRs in the capsule during mid-pregnancy remains to be determined.

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Plasma Oxytocin Concentrations in Men, Nonpregnant Women, and Pregnant Women before and during Spontaneous Labor*

Cited by 153 publications

References 20 publications

Vasopressin and oxytocin levels during normal pregnancy: effects of chronic dietary sodium restriction

Vasopressin and oxytocin levels during normal pregnancy: effects of chronic dietary sodium restriction

Advances in the role of oxytocin receptors in human parturition

Regulation of oxytocin receptor in the placentome capsule throughout pregnancy in the ewe: the possible role of oestradiol receptor, progesterone receptor and aromatase

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