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

When Rana cancrivora were collected from fresh water and dehydrated (weight loss 4-10%) by exposure to saline, the plasma titre of hydro-osmotic activity, measured by amphibian bladder assay, was increased three-to fourfold. This activity, which was abolished by thioglycollate and by incubation with tyrosinase or trypsin, was ascribed to vasotocin. The plasma vasotocin activities (hydrated and dehydrated frogs respectively) were estimated to be 0-03-0-5 and 0-15-0-25 mug/1; if referred to oxytocin as a standard the equivalent values were 10 and 30-60 mu./ml. Assuming that the increase represented released pituitary hormone, the amount of vasotocin released by osmotic dehydration was calculated to be of the order of 1 ng. Pituitary glands of hydrated and dehydrated frogs were estimated to have 0.15 and 0-18 mug vasotocin/gland respectively. The possible physiological function of released vasotocin in promoting reabsorption of urea from the urinary bladder is discussed in relation to the euryhaline ability of R. cancrivora.
J Endocrinol 1975 Sep
PMID:Vasotocin-like activity in the plasms of the euryhaline frog (Rana cancrivora) after transfer from fresh water to saline. 81 47

Plasma levels of prolactin and TSH were determined by radioimmunoassay in urethaneanaesthetized lactating rats during suckling. Oxytocin release was monitored by recording intramammary pressure. Application of ten pups, 3 h after administration of urethane (1-1 g/kg, i.p.), evoked a parallel rise in prolactin and TSH concentrations which reached a maximum during the 3rd hour of suckling and then declined. Peak hormone concentrations represented a 25-fold increase in prolactin and a ten-fold increase in TSH. Suckling also elicited a pulsatile (every 5-10 min) release of 0-5--1-0 mu. oxytocin. The gradual rise in prolactin and TSH occurred between the 1st and 20th oxytocin pulses. Intravenous injection of thyrotrophin-releasing hormone (TRH) into unsuckled, anaesthetized lactating rats resulted in a 7- to 30-fold increase in TSH concentration, whereas prolactin levels showed no substantial change. These results indicate that suckling releases TSH as well as prolactin in the urethaneanaesthetized rat. However, the absence of prolactin release after injections of TRH makes it unlikely that both endocrine responses are regulated solely by the actions of this one releasing hormone.
J Endocrinol 1976 Sep
PMID:Plasma concentrations of prolactin and thyrotrophin during suckling in urethane-anaesthetized rats. 82 93

2 cases of undiagnosed abdominal pregnancy observed in a 1-year period are reported. Both were complications of 2nd-trimester induced abortion. In case 1, a 25-year old black woman (gravida 5, para 2), multiple attempts at amniocentesis resulted only in bloody fluid. Intramuscular methyl-prostaglandin F2alpha (PGF2alpha) was administered and hypertonic saline was infused, but neither uterine cramping nor rupture of the membranes followed. PGE2 vaginal suppositories produced no change. Laparotomy revealed a large abdominal mass superimposed on the fundus, extending posterior to the uterus in the cul-de-sac. The amniotic sac contained a 15 ounce stillborn fetus. In case 2, a 33-year old black woman (gravida 2, para 1), bloody fluid was again obtained on amniocentesis. Intravaginal PGE2 suppositories and oxytocin were given, but dilation did not proceed despite uterine cramping. Examination revealed a cystic mass to the right of the uterus and fixed to the cul-de-sac. Laparotomy resulted in removal of a 45 gm macerated fetus. There appeared to be a rent in the right tube from which the gestation had been extruded with secondary implantation upon the abdominal viscera. A 3rd abdominal pregnancy observed in that time period resulted in a live birth at 41.5 weeks of gestation. Clinically, the diagnosis of abdominal pregnancy can be made by sounding the uterus. Laparoscopy will differentiate between abdominal and cornual pregnancy. Sonography is an additional diagnostic aid. When 2nd trimester abortion patients are given PGE2 as a vaginal suppository, 97% abort within 36 hours. Side effects such as vomiting, diarrhea, temperature elevation, and facial flush indicate adequate absorption. When these signs are present but expulsion of fetal tissue or membrane rupture do not occur, extrauterine gestation should be considered.
Am J Obstet Gynecol 1977 Sep 01
PMID:Undiagnosed abdominal pregnancy with inadvertent prostaglandin administration. 90 Jan 63

1. In conscious lactating goats a significant correlation was found between blood-milk potential difference (p.d.) and milk [lactose] such that in goats with a lower milk [lactose], milk was more negative with respect to blood.2. When mannose was substituted for glucose in the substrate mixture of isolated perfused goat mammary glands, milk yield and milk [lactose] fell while milk [Na] and [K] increased; in parallel experiments the blood-milk p.d. changed such that milk became more negative with respect to blood. These changes were reversed following the addition of glucose.3. When milk was made hypertonic by the addition of hyperosmotic sucrose or lactose solutions, water entered milk osmotically and milk became electrically less negative or even positive with respect to blood in goats, cows and guinea-pigs.4. No effect on p.d. was apparent following the addition of isosmotic sucrose to milk in goats.5. When milk was held in the teat of goats by a pneumatic cuff around the base of the teat, no effect on p.d. was apparent when hyperosmotic sucrose was introduced into this teat pouch.6. It is suggested that waterflow-induced potentials (the streaming potential and the transport number effect) can be induced across the mammary epithelium.7. In goats exogenous oxytocin lowered milk [lactose] and blood-milk p.d. became less negative with respect to blood.8. In non-lactating and mastitic glands of goats the blood-milk p.d. was within 0.5-2.5 mV of zero.9. The effects of oxytocin, and the low p.d. in non-lactating and mastitic glands, are compatible with the view that in such circumstances there is a paracellular pathway across the mammary epithelium which partially short-circuits the two sides.10. It is suggested that, with water being drawn osmotically into milk to dilute newly formed lactose, waterflow-induced potentials may be responsible for establishing the normal p.d. across the apical membrane of the secretary cell, thereby keeping milk [K] and [Na] lower than in intracellular fluid.
J Physiol 1977 Sep
PMID:Mechanism of milk secretion: milk composition in relation to potential difference across the mammary epithelium. 90 3

Termination of pregnancy in missed abortion and intra-uterine fetal death was accomplished using vaginal suppositories of 20 mg PGE2 in 31 cases and the results were compared with oxytocin induction (with or without estrogen pre-treatment) in 17 cases at the doses routinely used in our hospital. The PG suppositories proved much more superior (96.7%) than oxytocin (47.7%), but induced a higher rate of side effects. The latter were not serious and were generally tolerated by the patients. There was a positive correlation between duration of fetal retention in utero and the induction expulsion time. The over all patient acceptance of the method was quite favourable and the approach appears to be a definite advance towards management of these cases.
Prostaglandins 1977 Sep
PMID:Management of missed abortion and fetal death in utero. 90 80

The uptake of the RNA precursor [3H] orotic acid by 18 brain regions of male rats was measured after intracarotid injection and a survival time of 15 s. Ocytocin added to the injected solutions (final concentrations: 1 to 1000 mU/ml) caused a dose-dependent enhancement of tracer uptake by 11 areas. Some of these regions (e.g. hippocampus) are thought to be involved in the behavioral effects of vasopressin and other peptide hormones (Van Wimersma Greidanus et al., 1975 a). Results of experiments in which the net uptake of tritiated water was used as a measure of relative blood flow led us to the conclusion that the blood-brain barrier permeability to [3H] orotic acid rather than the cerebral blood flow is changed by ocytocin. The present results support the assumption that the enhanced precursor supply caused by ocytocin might contribute to the influence of this peptide hormone on memory consolidation.
Endokrinologie 1977 Sep
PMID:[Effect of oxytocin on regional 3H-orotic acid uptake in rat brain]. 92 28

Bovine neurophysin I and neurophysin II (bNpI and bNpII) have been assayed by radioimmunoassay in the jugular venous blood of cows during parturition. In general, low bNpI levels were detected on the day before labour began and during the first stage of labour. Neurophysin I was present in appreciable quantities in blood taken during the second stage of labour and in most cows the concentrations rose to a maximum during the expulsive stage. After delivery, the concentration of bNpI in the blood diminished. This pattern of release is similar to that reported for oxytocin at parturition in cows. As with bNpI, maximum levels of bNpII occurred during the expulsive stage of labour in some animals. In others, bNpII concentrations were very low or absent. Low concentrations of bNpII were found at the other stages of labour. Examination of the results from individual animals indicated that the release of the two neurophysins can be independent.
J Endocrinol 1977 Sep
PMID:Release of neurophysins I and II during and after parturition in cows. 92 73

In attempting to design an antagonist of the antidiuretic response to arginine-vasopressin (AVP) [1-deaminopenicillamine,4-valine,8-D-arginine]vasopressin (dPVDAVP) was synthesized by the solid-phase method and assayed for antidiuretic, vasopressor, and oxytocic activities. dPVDAVP has an antidiuretic potency of 123 +/- 22 units/mg, one-tenth that of its parent [deamino,4-valine,8-D-arginine]vasopressin (dVDAVP). Like dVDAVP its antidiuretic effect in conscious diabetes insipidus rats is greatly prolonged when compared to AVP. dPVDAVP causes a prolonged inhibition of vasopressor responses to AVP but not to norepinephrine or angiotensin II. It has an antivasopressor pA2 value of 7.82 +/- 0.05 when tested against AVP. Thus the penicillamine substitution at position 1 in dVDAVP increased its antivasopressor activity sixfold (dVDAVP has a pA2 value of 7.03 +/- 0.11). dPVDAVP is thus the most potent vasopressor antagonist yet reported. dPVDAVP was also found to be a potent inhibitor of the in vitro oxytocic response to oxytocin (pA2 value = 7.23 +/- 0.04). dPVDAVP with its potent and specific ability to antagonize the vasopressor effects of AVP should be a useful pharmacological tool with which to explore the possible participation of AVP's potent vasoconstrictor properties in cardiovascular regulation in physiological and pathological states.
J Med Chem 1977 Sep
PMID:[1-deaminopenicillamine,4-valine]-8-D-arginine-vasopressin, a highly potent inhibitor of the vasopressor response to arginine-vasopressin. 92 26

Serial blood samples were obtained from 97 women in spontaneous labor, and oxytocin levels were determined by a sensitive and highly specific radioimmunoassay. The following observations were made: (1) The hormone is released in a series of "spurts"; (2) the peak levels achieved are usually 2 to 5 muU per milliliter and never exceed 12.5 muU per milliliter; (3) the frequency of spurt release increases as labor progresses, reaching a maximum in the second stage; (4) the frequency of spurt release is reduced during intravenous infusion of alcohol at levels which produce no obvious effect on uterine activity.
Am J Obstet Gynecol 1976 Sep 15
PMID:Observations on maternal oxytocin release during human labor and the effect of intravenous alcohol administration. 96 64

Neurohypophyseal dispersions and fractions enriched for neurosecretosomes and pituicytes were prepared from rats subjected to 6 days of water deprivation and 9-10 days of lactation as stimuli of the hypothalamo-neurohypophyseal system (HNS). After water deprivation the content of the fractions changed in such a way that the neurosecretosomes, and to a lesser extent also the pituicytes, accumulated at a lower density within the gradient used for separation. Stimulation by means of lactation did not show such changes when a comparison was made with dioestrus. Microchemical and histochemical tests for acid phosphatase showed that most of the activity in the controls was present in the neurosecretosomes. A rough calculation, which takes into account the different yields for the dispersion elements, showed a rather equal distribution for acid phosphatase activity between axonal and pituicytic compartments of the intact neurohypophysis. The known acid phosphatase activity response of the neural lobe after HNS stimulation, which was also detectable in the dispersion, resulted histochemically in an increased staining intensity for both neurosecretosomes and pituicytes, but with microassay it was distributed along a gradient similar to oxytocin. It was therefore concluded that this lysosomal enzyme response within the neurophypophysis is preferentially localized in the neurohypophysis is preferentially localized in the neurosecretory axons.
Brain Res 1976 Sep 17
PMID:Acid phosphatase in rat neurohypophyseal dispersions and its fractions enriched for neurosecretosomes and pituicytes after water deprivation and lactation. 96 51


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