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

Oxytocin (OT) release within the brain is thought to play a major role in inducing maternal behaviour in a number of mammalian species but little is known about the sites of release which are important in this respect. We have investigated whether the paraventricular nucleus of the hypothalamus (PVN) is a site of OT action on maternal behaviour in the sheep. In vivo microdialysis and retrodialysis was used to determine whether OT is released in the region of the PVN during the post-partum induction of maternal behaviour and if its release at this site can stimulate maternal behaviour in non-pregnant animals. In vivo sampling showed that OT concentrations increased significantly in the region of PVN at birth. When OT was retrodialysed bilaterally into the PVN (1 or 10 microM) of multiparous ewes treated with progesterone and oestradiol to stimulate lactation, maternal behaviour was induced in a significant number of animals (1 microM, 6/8 and 10 microM, 5/8) compared with controls (0/8 ewes). Similar infusions of the ring structure of OT, tocinoic acid (TOC-10 microM), also induced maternal behaviour in a significant proportion of animals (5/6 ewes) as did intracerebroventricular (ICV) OT (6/8 ewes) and artificial stimulation of the vagina and cervix (VCS, 8/9 ewes). On the other hand, vasopressin (AVP) 1 microM did not induce maternal behaviour in any ewes and a 10 microM dose only induced it in 2/8 animals. The neurochemical changes accompanying the above treatments were also investigated. Noradrenaline concentrations increased in the PVN after the retrodialysis administration of OT 1 microM and 10 microM, TOC 10 microM and AVP 1 microM, OT ICV and VCS. Dopamine concentrations were also increased by OT 10 microM, TOC 10 microM, AVP 1microM and OT ICV. Aspartate and glutamate concentrations were significantly reduced by retrodialysis infusions of OT 1 microM and AVP 1 and 10 microM but not by any other treatment. Finally, the retrodialysis infusion of OT and TOC, as well as ICV OT, significantly increased plasma OT release whereas AVP infusions did not. These results provide evidence that OT is released in the PVN during parturition and is important for the induction of maternal behaviour. It seems probable that OT release at this site has a positive feedback effect on both parvocellular and magnocellular OT neurons to facilitate co-ordinated OT release both in central OT terminal regions (to facilitate maternal behaviour) and peripherally into the blood (to facilitate uterine contractions/milk let down). The potential functional roles for the actions of OT on monoamine and amino acid transmitter release in the PVN are discussed.
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PMID:The role of oxytocin release in the paraventricular nucleus in the control of maternal behaviour in the sheep. 873 Jun 50

Mesotocin (MT), the oxytocin-like peptide of the tammar wallaby (Macropus eugenii) is important for delivery of live young. The tammar mesotocin receptor (MTR) was first characterized using the iodinated oxytocin receptor antagonist [125I]d(CH2)5 [Tyr(Me)2, Tyr4, Orn8, Tyr-NH(2)9]-vasotocin. MTR concentrations were then measured in matched samples of gravid and nongravid myometrium and median vagina at different stages of the 26-day pregnancy. MTR concentrations in both the gravid and nongravid myometrium changed significantly (ANOVA, p < 0.01) during pregnancy. There was no difference in MTR concentrations between uteri on Days 8-22. From Day 23 of pregnancy, MTR concentrations in the gravid myometrium increased (615.8 +/- 144.0 fmol/mg protein), whereas in the nongravid myometrium, they remained unchanged (248.6 +/- 65.5 fmol/mg protein). Receptor concentrations were high in the gravid myometrium during the last 3 days of pregnancy but decreased significantly in the nongravid myometrium. In the median vagina, MTR concentrations were low compared with myometrial tissues and did not increase at term. Changes in MTR concentrations paralleled changes in uterine responsiveness to exogenous MT in vitro. Our data show that MTR concentrations and the responsiveness to MT differ between the gravid and nongravid myometrium during pregnancy. The increase in MTRs in the gravid myometrium and the decrease in the nongravid suggest that different factors influence these receptors in the separate uteri, independent of systemic influence.
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PMID:Evidence for a local fetal influence on myometrial oxytocin receptors during pregnancy in the tammar wallaby (Macropus eugenii). 900 50

A systematic search for neuroendocrine (NE) cells in the urogenital organs of the pig was carried out by means of Linder's argyrophil method and immunohistochemical techniques. The occurrence, distribution and immunohistochemical character of NE cells (paraneurons) were studied in the vaginal vestibulum, vagina, uterus, oviduct, ovary, urethra, urinary bladder and ureter. In the vestibular glands paraneurons were found to be the most numerous, while a moderate number of these cells occurred in the uterine horn and in the urethra. A distinctly smaller number of paraneurons was present in the oviduct and only occasional NE cells were observed in the urinary bladder. Immunohistochemistry was performed by using the peroxidase-antiperoxidase procedure. Different subpopulations of paraneurons were distinguishable. Chromogranin A-positive paraneurons were found in the vestibular glands, uterine horns, oviducts, urethra and urinary bladder. Somatostatin positivity was observed in NE cells of the vestibular gland, uterine horn, oviduct and urethra. The subpopulation of serotonin-positive paraneurons was present in the vestibular gland and urethra. Bombesin, vasoactive intestinal polypeptide, cholecystokinin, substance P, nitric oxide synthase, beta-endorphin, insulin, adrenocorticotropic hormone, oxytocin and thyroid-stimulating hormone antibodies gave negative reactions in the studied NE cells.
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PMID:Neuroendocrine cells in the female urogenital tract of the pig, and their immunohistochemical characterization. 909 38

Induction of immediate-early genes (IEGs), such as c-fos, has been widely used to mark the activation of brain regions following different types of sexual stimulation and behavior. A relatively common set of hormone-concentrating basal forebrain and midbrain structures in female and male rodents is activated by copulatory stimulation, in particular, stimulation of sensory nerves that innervate the penis or vagina/cervix, olfactory or pheromonal stimuli, and conditioned sexual incentives. These regions include the preoptic area, lateral septum, bed nucleus of the stria terminalis, paraventricular hypothalamus, ventromedial hypothalamus, medial amygdala, ventral premammillary nuclei, ventral tegmentum, central tegmental field, mesencephalic central gray, and peripeduncular nuclei. Regions that do not contain classic intracellular steroid receptors, such as the ventral and dorsal striatum or cortex, are also activated. IEGs have also been colocalized with cytoplasmic proteins like GnRH and oxytocin, and have been used in conjunction with retrograde tracers to reveal functional pathways associated with different sexual behaviors. Steroid hormones can also alter the ability of sexual stimulation to induce IEGs. Despite the many similarities, some differences in IEG induction between sexes have also been found. We review these findings and raise the question of what IEG induction in the brain actually means for sexual behavior, that is, whether it indicates the perception of sexual stimulation, commands for motor output, or the stimulation of a future behavioral or neuroendocrine event related to the consequences of sexual stimulation. To understand the role of a particular activated region, the behavioral or neuroendocrine effects of lesions, electrical stimulation, drug or hormone infusions, must also be known.
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PMID:Implications of immediate-early gene induction in the brain following sexual stimulation of female and male rodents. 937 Feb 4

Mestocin receptor concentrations in membrane preparations from reproductive tissues of the tammar Macropus eugenii throughout gestation and lactation were assessed using [3H]-oxytocin as the ligand. There was a single binding site which bound both mesotocin and oxytocin with high and similar affinities. Mesotocin receptor concentrations in the myometrium were low (708 +/- 199 fmol mg-1 protein) in early and middle gestation but increased significantly on day 23 of pregnancy of the 26-day gestation period to 1921 +/- 552 fmol mg-1 protein. Myometrial receptors reached a peak of 2483 +/- 575 fmol mg-1 protein on days 25 and 26 of gestation, but returned to basal levels about an hour after birth. Receptor concentrations in the contralateral non-gravid uterus were much lower (605 +/- 75 fmol mg-1) and did not significantly increase throughout the period of gestation but dropped one day before birth. Mesotocin receptors were undetectable in the endometrium, the yolk sac placenta and the lateral, median and anterior vagina of all animals tested. In the lactating mammary gland after birth mesotocin receptors were initially high (588 +/- 38 fmol mg-1) but decreased after 200 days and by late lactation were 224 +/- 55 fmol mg-1 protein on day 240, close to the time of weaning. Mesotocin receptors in the ipsilateral non-lactating gland were also high in early lactation (430 +/- 153 fmol mg-1) and declined in late lactation (62 +/- 20 fmol mg-1). The changing concentrations of mesotocin receptors in pregnancy and lactation demonstrate that they are specifically regulated in tammar reproductive tissues. The increase in mesotocin receptors in gravid, but not in the non-gravid myometrium three days before birth may make the uterus responsive to the surge of mesotocin at birth. Since this rise is unilateral and only occurs in the gravid myometrium it must be due to local effects from the ipsilateral ovary or the feto-placental unit. Likewise, the down-regulation of mesotocin receptors in the contralateral, non-gravid myometrium may be due to its proximity to the developing follicle. The changing concentrations in the lactating and the adjacent, non-lactating mammary gland also reflect a differential regulation of mesotocin receptors, probably mediated via the sucking stimulus. Thus, local influences appear to be of primary importance in the regulation of mesotocin receptors during reproduction in this marsupial.
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PMID:Mesotocin receptors during pregnancy, parturition and lactation in the tammar wallaby. 967 70

The balloon catheter method has been described as an effective method for cervical ripening hitherto used exclusively before rupture of the membranes. We found it of interest to perform a pilot study of the balloon catheter method after rupture of the membranes. In 18 nulliparous women, with an unripe cervix (Bishop score < or = 5) 48 h after prelabor rupture of the membranes at term, cervical ripening was performed using a 26-gauge balloon catheter. Seventy six percent of these women delivered vaginally. Clinical and neonatal outcome data did not differ as compared with term pregnant women who entered labor spontaneously or had a ripe cervix (Bishop score >5) and labor induced with oxytocin within 48 h after prelabor rupture of the membranes. Despite visualization of a pool of amniotic fluid in the vagina on speculum examination on admission, there was a high proportion of patients with an intact forebag observed during the birth process. This preliminary report indicates that the balloon catheter method might be a well-tolerated, safe, and effective method for induction of labor after rupture of the membranes at term.
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PMID:Balloon catheter for induction of labor in nulliparous women with prelabor rupture of the membranes at term. A preliminary report. 969 32

A particular failure of the milk-ejection reflex in dairy cows is described on the base of own experiences in farms and reports from literature. Four cases are reported more in detail. Quantity and fat content of cisternal, alveolar and residual milk fractions, oxytocin content in blood serum, milk-ejection after manual teat stimulation, after massage of the clitoris or rectal stimulation of the vagina and cervix were investigated. This failure of the milk-ejection is observed mostly in primiparous cows and always at the begin of the lactation period. It is complete and permanent unless successfully treated, and seems to be based on an central inhibition of the oxytocin release. Treatment consists of thorough udder stimulation and milking followed by an i.v. application of oxytocin in order to remove the residual milk portion. The condition has a good prognosis, if the treatment is carried out regularly for some days and even weeks. Acute Mastitis is the main differential diagnosis.
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PMID:[Failure of milk ejection reflex in primiparous cows from the differential diagnostic and therapeutic aspects]. 969 50

Adenomyosis of the uterus is a serious problem for women of reproductive age because of its possible consequence of infertility. We present the case of a woman who had adenomyosis of the uterus, a successful spontaneous pregnancy, and delayed and tenacious postpartum hemorrhage that did not respond to conservative treatment. The 26-year-old woman, gravida 1, para 1, suffered from fulminating vaginal bleeding and associated shock 20 days after the delivery of a 3,450-g female by Cesarean section. Conservative treatment included uterine compression and massage, blood transfusion, intravenous administration of high-dosage estrogen, oxytocin and sulprostone (prostaglandin E analogue), and gauze packing from the vagina into the uterine cavity. Despite treatment, the patient went into shock due to persistent vaginal bleeding. Emergency exploratoric assessment laparotomy was performed, followed by a stotal hysterectomy. Pathology revealed extensive adenomyosis of the uterus without other significant abnormality. The potential dangers of adenomyosis in pregnancy should not be overlooked when patients seek treatment for infertility.
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PMID:Delayed postpartum hemorrhage in adenomyosis: a case report. 974 67

Arginine vasopressin is the main hormone involved in the regulation of body fluid osmolality. The hormone is released by the posterior pituitary whenever water deprivation causes an increased plasma osmolality or whenever the cardiovascular system is challenged by hypovolaemia and/or hypotension. The main site of action of this hormone is the renal collecting duct, but vasopressin is also a potent vasopressor and neurotransmitter, it has a role in the secretion of corticotrophin, in the regulation of the cardiovascular system, temperature and other visceral functions. Vasopressin also promotes the release of coagulation factors by vascular endothelium and increases platelet aggregability. In addition to its classical contractile effect on uterine myometrial and mammary glandular myoepithelial cells, oxytocin acts as neurotransmitter, stimulates endometrial prostaglandin production, pituitary prolactin secretion, luteolysis, sperm transport and natriuresis, and may play a role in immune function. Sensorial stimuli arising from the cervix and vagina as well as stimulation of the breast can induce secretion of oxytocin from the posterior pituitary. There are many vasopressin and oxytocin analogues (agonists and antagonists) that are synthetized with the goal of increasing duration of action and selectivity for the receptor subtypes, while non-peptide antagonists are orally active. The oxytocin and the vasopressin V1a, V1b and V2 receptors have recently been cloned and shown to form a sub-family within the large superfamily of G-protein-linked receptors. Renal V2 receptors mediate vasopressin-induced water reabsorption via induction of intracellular cAMP production in collecting duct cells. Most remaining actions of vasopressin on blood vessel constriction, liver glycogenolysis, platelet adhesion, adrenal angiotensin II secretion and certain brain functions are mediated via V1a-type receptors that are coupled to a Gq/11 protein. V1 receptor activation leads to stimulation of phospholipases C, D and A2, and an increase in intracellular calcium. Vasopressin stimulates pituitary corticotrophin release via a third vasopressin receptor type (V1b) which is present in corticotrophs. Oxytocin induces myometrial contraction, endometrial prostaglandin F2a production, mammary gland milk ejection, renal natriuresis and specific sexual, affilitative and maternal behaviours via oxytocin receptors which are also coupled to a G1/11 protein. Although only one oxytocin receptor type has been cloned so far, recent binding studies indicate that uterine endometrial oxytocin receptors may constitute a distinct receptor subtype. Expression of oxytocin receptors have relevant up- and down-regulation by oestrogens and progesterone.
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PMID:[Hormones of the posterior region of the hypophyseal gland]. 986 66

Eleven light-breed pregnant mares (335 to 347 d gestaton) were used to evaluate the use of prostaglandin E2 as a cervical ripening agent prior to induction of parturition during the months of April and May. Six hours prior to induction, each mare's cervix was examined per vagina for softness and dilation. Each mare was then assigned to 1 of 2 treatment groups: Group PGE mares (n = 7) received 2.0 to 2.5 mg prostaglandin E2 deposited intracervically; Group SAL mares (n = 4) received 0.5 mL of sterile NaCl deposited intracervically. Six hours later, the mares were readied for parturition by wrapping the tail, scrubbing and rinsing the perineum and udder, and examining the cervix as previously described. Each mare was then administered 15 U, i.v. oxytocin at 15-min intervals until the chorioallantois ruptured. Intervals from initial oxytocin injection until rupture of the chorioallantois, from initial oxytocin injection until delivery of the foal, from delivery of the foal until the foal stood unassisted, and from delivery of the foal until the foal suckled were recorded. Mean cervical dilation immediately prior to induction of parturition tended to be greater in Group PGE mares (3.9 +/- 1.7 cm) than in Group SAL mares (1.9 +/- 1.9 cm; P = 0.10). Mean change in cervical dilation over the 6-h period prior to induction (3.4 +/- 1.9 cm vs 1.5 +/- 2.1 cm), mean number of injections of oxytocin required until the chorioallantois ruptured (1.9 +/- 0.7 vs 2.5 +/- 1.0), and mean intervals from initial injection of oxytocin to rupture of the chorioallantois (20 +/- 10 min vs 28 +/- 19 min) and delivery of the foal (28 +/- 7 min vs 34 +/- 22 min) were not different between Group PGE and SAL mares, respectively (P > 0.10). The proportion of foals that stood within 1 h of birth also did not differ between Group PGE foals (6/7; 86%) and Group SAL foals (3/4; 75%; Chi-square = 0.17; P > 0.10). The proportion of foals that nursed within 2 h of birth was higher in Group PGE foals (6/7; 86%) than in Group SAL foals (1/4; 25%; Chi-square = 4.02; P < 0.05). Premature separation requiring manual rupture of the chorioallantois at the vulvar labia occurred in 1 Group PGE mare (cervical dilation of 1.5 cm at time of induction) and 1 Group SAL mare (cervix closed and firm at time of induction). Foals born from the 2 mares with premature placental separation had the longest intervals from initial oxytocin injection to delivery, delivery to ability to stand unassisted, and delivery to suckling within their respective treatment groups. In summary, it appears that cervical ripening prior to induction of parturition favors shorter deliveries and foal vigor. Intracervical administration of prostaglandin E2 may prove useful for ripening the cervix of the mare prior to induction of parturition. Further studies are indicated to determine optimal dosage and method of administration of prostaglandin E2.
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PMID:Use of prostaglandin E2 to ripen the cervix of the mare prior to induction of parturition. 1073 62


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