Regulation of Oxytocin Secretion

Centre for Integrative Physiology, The University of Edinburgh College of Medicine and Veterinary Sciences, Edinburgh EH8 9XD, United Kingdom.
Vitamins & Hormones (Impact Factor: 2.04). 02/2005; 71:27-58. DOI: 10.1016/S0083-6729(05)71002-5
Source: PubMed

ABSTRACT A baby sucks at a mother's breast for comfort and, of course, for milk. Milk is made in specialized cells of the mammary gland, and for a baby to feed, the milk must be released into a collecting chamber from where it can be extracted by sucking. Milk "let-down" is a reflex response to the suckling and kneading of the nipple--and sometimes in response to the sight, smell, and sound of the baby--and is ultimately affected by the secretion of oxytocin. Oxytocin has many physiological roles, but its only irreplaceable role is to mediate milk let-down: oxytocin-deficient mice cannot feed their young; the pups suckle but no milk is let down, and they will die unless cross-fostered. Most other physiological roles of oxytocin, including its role in parturition, are redundant in the sense that the roles can be assumed by other mechanisms in the absence of oxytocin throughout development and adult life. Nevertheless, physiological function in these roles can be altered or impaired by acute interventions that alter oxytocin secretion or change the actions of oxytocin. Here we focus on the diverse stimuli that regulate oxytocin secretion and on the apparent diversity of the roles for oxytocin.

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    • "Moreover, women's plasma oxytocin concentrations during both early pregnancy and the early postpartum period showed significant positive correlations with maternal behavior (Feldman et al., 2007). These correlational findings in macaques and women must be interpreted cautiously, however, in view of the possible dissociation between peripheral and central oxytocin concentrations, the failure of peripheral oxytocin to penetrate into the brain, and the acute effects of suckling bouts on circulating oxytocin levels (Leng et al., 2005; Neumann, 2008). "
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    ABSTRACT: In nonhuman primates and humans, similar to other mammals, hormones are not strictly necessary for the expression of maternal behavior, but nevertheless influence variation in maternal responsiveness and parental behavior both within and between individuals. A growing number of correlational and experimental studies have indicated that high circulating estrogen concentrations during pregnancy increase maternal motivation and responsiveness to infant stimuli, while effects of prepartum or postpartum estrogens and progestogens on maternal behavior are less clear. Prolactin is thought to play a role in promoting paternal and alloparental care in primates, but little is known about the relationship between this hormone and maternal behavior. High circulating cortisol levels appear to enhance arousal and responsiveness to infant stimuli in young, relatively inexperienced female primates, but interfere with the expression of maternal behavior in older and more experienced mothers. Among neuropeptides and neurotransmitters, preliminary evidence indicates that oxytocin and endogenous opioids affect maternal attachment to infants, including maintenance of contact, grooming, and responses to separation. Brain serotonin affects anxiety and impulsivity, which in turn may affect maternal behaviors such as infant retrieval or rejection of infants' attempts to make contact with the mother. Although our understanding of the neuroendocrine correlates of primate maternal behavior has grown substantially in the last two decades, very little is known about the mechanisms underlying these effects, e.g., the extent to which these mechanisms may involve changes in perception, emotion, or cognition.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 09/2010; 35(5):1192-204. DOI:10.1016/j.pnpbp.2010.09.017 · 3.69 Impact Factor
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    • "Until recently, oxytocin, the neurohypophysial neuropeptide , has been known for its pivotal role in the progress of parturition and initiation of milk ejection (Russell et al. 2003; Leng et al. 2005). The regulatory spectrum of oxytocin is now known to be substantially wider. "
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    ABSTRACT: The present study was aimed at determining the role of centrally released oxytocin in regulation of blood pressure and heart rate (HR) under resting conditions and during an acute air-jet stress in rats with a myocardial infarction and controls infarcted. Four weeks after ligation of a coronary artery or sham surgery, conscious Sprague Dawley rats were subjected to one of the following intracerebroventricular (ICV) infusions: (1) 0.9% NaCl (control), (2) oxytocin, (3) oxytocin receptor antagonist {desGly-NH(2)-d(CH(2))(5)[D-Tyr(2)Thr(4)]OVT}(OXYANT). Resting arterial blood pressure and HR were not affected by any of the ICV infusions either in the infarcted or sham-operated rats. In the control experiments, the pressor and tachycardic responses to the air jet of infarcted rats were significantly greater than in the sham-operated rats. OXYANT significantly enhanced the cardiovascular responses to stress only in the sham-operated rats whereas oxytocin significantly attenuated both responses in the infarcted but not in the sham-operated rats. The results suggest that centrally released endogenous oxytocin significantly reduces the cardiovascular responses to the acute stressor in control rats. This buffering function of the brain-oxytocin system is not efficient during the post-myocardial infarction state, however it may be restored by central administration of exogenous oxytocin.
    Stress (Amsterdam, Netherlands) 11/2009; 12(6):517-25. DOI:10.3109/10253890802687688 · 2.72 Impact Factor
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