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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Between 60 and 90% of female house mice spontaneously kill unrelated young. A previous report indicated that subcutaneous administration of oxytocin significantly reduced the frequency of infanticide by virgin and pregnant females. However, in this study a distinction could not be made between an action of oxytocin on the CNS versus a secondary effect such as an enhanced release of prolactin by oxytocin. In the current experiment, oxytocin administered intracerebroventricularly was equally as effective at inhibiting infanticide as sc oxytocin. There was no difference in the effectiveness of oxytocin between groups of infanticidal females that were gonadally intact, ovariectomized, or estrogen treated. Pretreatment of infanticidal females with the prolactin inhibitors, bromocriptine and cysteamine, was also without effect on the ability of oxytocin to inhibit infanticide. Last, prolactin-inhibiting drugs had no significant effect on spontaneous parenting behavior by female mice. These data suggest that oxytocin acts directly on the CNS to alter behavior toward pups and that prolactin may not play a role in the maternal behavior of the house mouse.
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PMID:Oxytocin inhibits infanticide in female house mice (Mus domesticus). 222 49

We studied the mechanism of normal lactation, especially the roles of prolactin (PRL) and oxytocin (OXT) in the initiation of lactation, the lactation in the women complicated with endocrinological disorders, and medical therapies for stimulation and suppression of lactation. The level of serum PRL increases as pregnancy progresses, and reaches to a peak on the day of delivery. Despite high PRL level, milk secretion does not appear during pregnancy, because the sex steroid hormones suppress binding of PRL to the receptor in the mammary gland. The initiation of milk secretion in puerperal women seems to be closely related to an increase in PRL levels induced by adequate suckling. In the mechanism of suckling-induced PRL increase, OXT from posterior pituitary seems to have an important role. Furthermore, the poor response of PRL to suckling was due to insufficient stimulation to the nipples by suckling because the size of nipples were relatively small in these mothers. The other mechanism involved in lactation is suckling-induced OXT secretion. OXT stimulates milk ejection. Anxiety or fear may inhibit the OXT release. We demonstrated that the number of pulsatile release of OXT by nursing was significantly decreased by the psychological stress induced by mental calculation. In the puerperal women with prolactinomas after surgery, the serum PRL level did not increase during pregnancy and milk secretion in puerperium was poor. In the puerperal women with diabetes mellitus, milk secretion was also poor. One of the causes may be related to the low PRL response to suckling stimuli. PRL stimulates milk yield in the mammary gland, but is not commercially available.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Hormonal control of lactation]. 223 Apr 14

The aim of the present study was to examine suckling-related plasma levels of oxytocin and prolactin in early and established lactation and to correlate hormone profiles to success of lactation performance. Fifty-five primiparous women participated in the study. From each, 18 blood samples were drawn in connection with breast-feeding on day 4 post partum and after 3-4 months. Oxytocin and prolactin levels were determined with radio-immunoassay. Basal levels of both hormones were significantly higher 4 days post partum than 3-4 months later and after weaning. Basal prolactin levels fell significantly within 24 h of weaning. Oxytocin and prolactin levels rose in response to breast-feeding--an effect which persisted during the lactation period. The suckling-induced release of prolactin--but not that of oxytocin--was related to basal hormone levels. Basal as well as stimulated oxytocin levels obtained 4 days and 3-4 months post partum correlated significantly, indicating that each woman has an individual, characteristic level of this hormone. Milk yield did not correlate with oxytocin or prolactin levels, but prolactin levels recorded 3-4 months post partum did correlate with the remaining period of breast-feeding. In addition, mothers who breast-fed exclusively 3-4 months post partum had significantly higher oxytocin and prolactin levels than those who gave supplementary feed. There was a significant correlation between oxytocin levels at 4 days and birth weight of the infant.
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PMID:Oxytocin and prolactin levels in breast-feeding women. Correlation with milk yield and duration of breast-feeding. 224 61

The development of the human breast is dependent on the presence of ovarian steroids. The basic secretory units--the alveoli--continue to respond to steroids throughout the reproductive years. Lactogenesis is triggered by a rapid and drastic fall in progesterone at delivery and maintained by prolactin while the actual expulsion of milk from the breast depends on oxytocin. The composition of milk is very variable but is adequate to provide the sole source of nutrients for up to the first 6 months of life. Lactation suppresses ovarian activity probably through a disturbance in the pulsatile pattern of LH secretion but the degree of suppression depends on infant feeding patterns and perhaps on maternal nutritional status. Breastfeeding therefore confers a degree of protection against pregnancy but some artificial methods of contraception are appropriate for use during lactation. It is still not clear whether breastfeeding protects significantly against breast cancer.
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PMID:Physiology of lactation. 224 1

The roles of oxytocin and vasopressin on prolactin secretion were studied. Adult female Sprague-Dawley rats ovariectomized for two weeks and treated with a long-acting estrogen, polyestradiol phosphate for one week were used. Hormone administration and serial blood sampling were accomplished through indwelling intra-atrial catheters which were implanted two days before the experiment. Both oxytocin (20 micrograms/rat) and vasopressin (5 micrograms/rat) stimulated prolactin secretion within 10 min after injection and the effects were diminished by 30 min. In animals pretreated with a small dose of dopamine antagonist, sulpiride (1 microgram/rat), the effect of TRH on prolactin secretion was repeatedly shown to be potentiated. Same pretreatments with two different time intervals (30 and 60 min) between sulpiride and oxytocin/vasopressin administration, however, had no effect on oxytocin- or vasopressin-stimulated prolactin secretion. A vasopressin analog, 1-deamino-[D-Arg8]-vasopressin (dDAVP), with antidiuretic but no vasopressor activity was also used in the study. It was found that unlike vasopressin, dDAVP had no effect on prolactin secretion. In conclusion, both oxytocin and vasopressin can have a stimulatory effect on prolactin secretion when given in vivo. Unlike TRH, however, the action of oxytocin or vasopressin was not augmented by pretreatments of dopamine antagonist. The action of vasopressin on prolactin secretion may be a side effect of its vasopressor activity.
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PMID:Dopamine antagonism does not potentiate the effects of oxytocin and vasopressin on prolactin secretion. 226 68

Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treatments applied in vitro to endometrium from cyclic (CYC), pregnant (PREG) and estradiol-induced pseudopregnant (PSP) gilts. In Exp. 1, treatments (in 25 microliters .1 M NaHCO3) were 1) control (NaHCO3), 2) 125 ng oxytocin, 3) .25 micrograms prolactin, 4) 2.5 micrograms prolactin and 5) 5 micrograms pig conceptus secretory proteins (pCSP). Basal IP turnover on d 14 (estrus = d 0) for CYC was 3.9 to 5.0-fold greater than for PREG gilts and .6 to 1.1-fold greater than for PSP gilts (P less than .05). Oxytocin increased IP turnover 23 to 42% in CYC gilts (P less than .05), but not in PREG or PSP gilts. The treatment x reproductive status interaction (P less than .05) indicated that pCSP increased IP turnover 74 to 140% in PREG gilts but decreased it 18 to 22% in CYC and 17 to 50% in PSP gilts. In Exp. 2, treatments were applied in a 2 x 2 x 2 arrangement: 1) 0 or 125 ng oxytocin; 2) 0 or 2.5 micrograms prolactin and 3) 0 or 5 micrograms pCSP. Basal IP turnover on d 14 was 3.3 to 5.4-fold greater (P less than .05) in CYC than in PSP gilts and was affected by interaction (P less than .05) of pCSP and prolactin. Inositol phosphate turnover was increased by prolactin (12 to 22%) and by pCSP (7 to 34%) but, when combined, the stimulatory effects of each were eliminated.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Endometrial inositol phosphate turnover in pigs is reduced during pregnancy and estradiol-induced pseudopregnancy. 228 69

Circulating concentrations of 13,14-dihydro-15-keto PGF2 alpha (DHKF2 alpha), luteinizing hormone (LH) and prolactin (PRL) have been measured in cyclic ewes treated with continuous infusions of oxytocin, in order to investigate the mechanism by which the treatment delays luteal regression. Continuous infusion of oxytocin reduced prostaglandin F2 alpha (PGF2 alpha) secretion but had no detectable direct effect on LH or PRL. Oxytocin (3 nmol h-1 i.v.) given from Day 12 or 13 until Day 18 after oestrus delayed luteolysis, eight out of nine treated ewes not returning to behavioural oestrus until Day 29.1 +/- 3.2 (mean +/- s.e.m.; cycle length of control ewes 16.7 +/- 0.3 days). In the ewe in which oxytocin failed to prevent luteolysis, luteal regression had commenced before oxytocin treatment was started. In three ewes undergoing delayed luteolysis (cycle lengths, 21, 24 and 25 days) basal concentrations of PGF2 alpha (measured as DHKF2 alpha) were unchanged, but there was only one episode of PGF2 alpha secretion compared with 20 episodes in three control ewes. Prolactin secretion was pulsatile during oxytocin infusion, and levels were low following infusion in ewes with cycle length greater than 25 days while the corpora lutea were maintained. Circulating PRL concentrations were high in ewes undergoing delayed luteolysis but there was not discrete episode of PRL secretion associated with the pre-ovulatory LH surge in these animals. To investigate the possibility that the pattern of PGF2 alpha secretion was affected by depletion of oxytocin from corpora lutea, ewes previously treated with oxytocin to delay luteolysis were given a luteolytic dose of cloprostenol on Day 21 after oestrus. The amount of oxytocin secreted in response to cloprostenol was less than 10% of that seen in ewes similarly treated on Days 11-13 after oestrus. Low levels of luteal oxytocin may therefore reduce PGF2 alpha secretion in ewes undergoing delayed luteolysis.
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PMID:Effect of continuous infusion of oxytocin on prostaglandin F2 alpha secretion and luteolysis in the cyclic ewe. 233 92

Pantethine, a cysteamine precursor, depletes somatostatin in the cerebral cortex and hypothalamus and prolactin in the anterior pituitary and hypothalamus. This study investigated the effect of pantethine on oxytocin and arginine vasopressin content in the posterior pituitary and hypothalamus. Male Long-Evans rats were injected intraperitoneally with escalating doses of pantethine (i.e., 146.7 mg, 293.4 mg and 586.6 mg/100 gm body weight). Hormone content was determined by radioimmunoassay. Three hours after pantethine treatment, the oxytocin content in the posterior pituitary and the hypothalamus was markedly reduced with all doses of the drug. Vasopressin content in the posterior pituitary and hypothalamus was decreased but to a lesser extent than oxytocin and only with the highest dose of pantethine. Pantethine may act to reduce oxytocin and vasopressin content through intracellular conversion to cysteamine. The exact mechanism of action of pantethine on oxytocin and vasopressin remains to be elucidated.
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PMID:Changes in oxytocin and vasopressin content in posterior pituitary and hypothalamus following pantethine treatment. 240 77

An immunocytochemical analysis with 33 antisera was undertaken to investigate the localization of 25 different neurotransmitter-related antigens in the hypothalamic suprachiasmatic nucleus in the rat. To obtain estimates of relative densities of immunoreactive axons a stereological approach was used involving counting of intersections of immunoreactive axons with a superimposed semi-circle test grid. All neurotransmitter-related antigens found in perikarya within the suprachiasmatic nucleus, including those stained with antisera against bombesin, gastrin-releasing peptide, neurophysin, vasopressin, somatostatin, gamma-aminobutyrate, glutamate decarboxylase and vasoactive intestinal polypeptide were also found in axons within the nucleus. A greater number of these immunoreactive axons was found within the nucleus than in the adjacent anterior hypothalamus. The size of all immunoreactive axons in the suprachiasmatic nucleus was consistently small; immunoreactive axons were found ramifying widely in the nucleus, often ending with terminal boutons near perikarya immunoreactive for the same antigen. All neurotransmitter-related substances found in perikarya of the suprachiasmatic nucleus were also found in axons crossing over the midline to innervate the contralateral nucleus, providing an anatomical substrate for a high degree of communication between the paired nuclei. Axons immunoreactive for other putative transmitters including serotonin arising outside the nucleus were also found in high densities within the nucleus and crossing over the midline between the nuclei. Immunoreactivity for some transmitters was found in axons of similar densities within and outside the nucleus, including antisera against tyrosine hydroxylase; a small number of dopamine beta-hydroxylase and a few phenylethanolamine N-methyltransferase-immunoreactive axons were found in the SCN, suggesting that dopamine, norepinephrine and epinephrine may occur in a limited number of axons in the nucleus. Small numbers of axons immunoreactive with antisera raised against cholecystokinin, prolactin, substance P, thyrotropin-releasing hormone and choline acetyltransferase were found within the suprachiasmatic nucleus. Axons immunoreactive for luteinizing hormone-releasing hormone, adrenocorticotropic hormone, alpha-melanocyte-stimulating hormone and neurotensin were rarely found within the suprachiasmatic nucleus; axons immunoreactive for luteinizing hormone-releasing hormone, adrenocorticotropic hormone, cholecystokinin and tyrosine hydroxylase were found in both horizontal and coronal sections in the area between the left and right suprachiasmatic nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Neurotransmitters of the hypothalamic suprachiasmatic nucleus: immunocytochemical analysis of 25 neuronal antigens. 241 88

The relative levels of mRNAs for relaxin, prolactin, inhibin and oxytocin have been measured in porcine granulosa as well as luteal cells by hybridisation to single-stranded synthetic DNA. The likelihood of a paracrine function of oxytocin and prolactin in the porcine ovary was inferred from the in vitro effects of both hormones on progesterone secretion of ovarian cells. Both hormones were found to inhibit progesterone secretion of luteal cells. In contrast, only prolactin but not oxytocin stimulated progesterone secretion in granulosa cells.
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PMID:Demonstration of mRNAs for oxytocin and prolactin in porcine granulosa and luteal cells. Effects of these hormones on progesterone secretion in vitro. 242 59


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