Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Frequent blood samples were removed from a utero-ovarian vein, a jugular vein and a femoral artery of 5 ewes during luteolysis. Analysis of these samples for oxytocin-associated neurophysin revealed a significant venous-arterial difference across the ovary and uterus but not across the head. This occurred during the pulsatile surges as well as when levels were basal and confirms the corpus luteum as a major source of the pulsatile surges of oxytocin-associated neurophysin and oxytocin that occur during CL regression and also of the elevated luteal phase concentrations of both hormones. The pulsatile surges of oxytocin-associated neurophysin measured in the utero-ovarian vein were accompanied by the release of an approximately equimolar amount of oxytocin. The concentration of PGF-2 alpha in the utero-ovarian vein samples began to increase before the levels of oxytocin and oxytocin-associated neurophysin started to increase. This suggests that uterine PGF-2 alpha initiates the release of ovarian oxytocin and oxytocin-associated neurophysin during luteolysis in the ewe.
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PMID:Evidence for the pulsatile release of PGF-2 alpha inducing the release of ovarian oxytocin during luteolysis in the ewe. 345 54

In Exp. I, 0.5 mg oestradiol or vehicle (0.5 ml absolute ethanol + 0.5 ml 0.9% NaCl) was injected i.v. at 08:00 h on Day 14 (onset of oestrus = Day 0). Blood samples were obtained via a jugular catheter at 30 and 1 min before oestradiol and every 30 min for 10 h afterwards. Plasma was obtained and assayed for 15-keto-13,14-dihydro-PGF-2 alpha (PGFM) by radioimmunoassay. Before oestradiol, PGFM basal values were higher (P less than 0.01) in pregnant (N = 10) than nonpregnant (N = 6) ewes (193 +/- 30 vs 67 +/- 8 pg/ml). However, at 4-10 h after oestradiol, pregnant ewes (N = 5) had less variable (P less than 0.01) PGFM values than did nonpregnant ewes (N = 5). In Exp II, conceptus secretory proteins (CSP) were obtained by pooling medium from cultures of Day-16 sheep conceptuses (N = 40). Ewes received 750 micrograms CSP + 750 micrograms plasma protein (N = 6) or 1500 micrograms plasma protein (N = 6) per uterine horn at 08:00 h and 18:00 h on Days 12-14. All ewes received 0.5 mg oestradiol at 08:00 h on Day 14 and blood samples were collected as in Exp. I and assayed for PGFM. On Day 15, 3 ewes in each group received 10 i.u. oxytocin and 3 received saline i.v. at 08:00 h and blood samples were taken continuously from 10 min before to 60 min after treatment. Mean PGFM response to oestradiol was suppressed (P = 0.05) in CSP- vs plasma protein-treated ewes (371 +/- 129 vs 1188 +/- 139 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Proteins secreted by the sheep conceptus suppress induction of uterine prostaglandin F-2 alpha release by oestradiol and oxytocin. 345 55

Systemic intravenous infusion of physiological concentrations of PGF-2 alpha and its major metabolite, 13, 14-dihydro-15-keto-PGF-2 alpha (PGFM) into non-pregnant ewes possessing a corpus luteum induced the release of oxytocin-neurophysin. These results suggest that, during luteolysis, endogenous release of uterine PGF-2 alpha would be able to stimulate the release of ovarian oxytocin and oxytocin-neurophysin from the ovary.
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PMID:Effect of systemic intravenous infusion of PGF-2 alpha and 13,14-dihydro-15-keto-PGF-2 alpha on the release of oxytocin-associated neurophysin from the ovary in the ewe. 347 14

To observe the changes in endogenous oxytocics during spontaneous and induced labor, the plasma concentrations of oxytocin, prostaglandin E1 (PGE1) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured during labor in 9 cases of spontaneous labor (group 1), 10 of PGE2-induced labor (group 2), and 7 of PGF2 alpha-induced labor (group 3). Unextracted samples were used for radioimmunoassay of oxytocin. PGE and PGF were extracted and separated for radioimmunoassays of PGE1 and PGFM. Although oxytocin levels in groups 1 and 3 did not change during labor or slightly increased toward delivery, those in group 2 decreased as labor progressed. The mean oxytocin in group 2 was significantly lower at the times of established labor (15.3 +/- 3.2 microU/ml, mean +/- SE) and crowing of the fetal head (10.8 +/- 2.0 microU/ml) than before labor (52.7 +/- 14.8 microU/ml). Plasma PGE1 levels in groups 1 and 3 were low and did not change during labor. Plasma PGFM levels in groups 1 and 2 gradually rose toward delivery. These results suggest that exogenous PGE2 suppresses oxytocin secretion during labor and stimulates endogenous PGF2 alpha production, that endogenous PGE1 may not play an important role in the progress of spontaneous and PGF2 alpha-induced labor, and that endogenous PGF2 alpha may participate in the promotion of all kinds of labor.
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PMID:Changes in plasma oxytocin, prostaglandin E1, and 13,14-dihydro-15-keto-prostaglandin F2 alpha during labor induced by prostaglandin E2 or F2 alpha and spontaneous labor. 347 3

From a group of 11 cyclic mares, blood samples were collected at 3-min intervals for 2 h and at 15-min intervals for an additional 6 h during four stages of the oestrous cycle. Mean plasma oxytocin concentrations (pg/ml, LSM +/- se) were greater on Day 15 after ovulation (169.9 +/- 17.6) than on Day 0 (82.6 +/- 17.6; P less than 0.01), Day 3 (97.2 +/- 20.4, P less than 0.01) and Day 7 after ovulation (104.0 +/- 25.0, P less than 0.05). Oxytocin was secreted in a pulsatile manner throughout the oestrous cycle, with short (0-29 min), medium (30-89 min) and long (greater than 90 min) duration rhythms. No differences in pulse frequencies were observed throughout the oestrous cycle. Pulse amplitudes for rhythms of short and medium duration were greater on Day 7 after ovulation than on Day 0 (P less than 0.01 for short and P less than 0.05 for medium rhythms), Day 3 (P less than 0.01) and Day 15 after ovulation (P less than 0.05 for short rhythms). Fluctuations in baseline values for oxytocin over the 8-h sampling period were indicative of a possible circadian rhythm. These results are consistent with previous observations for the mare and other species that oxytocin is secreted in a pulsatile manner and may be involved in the regulation of the oestrous cycle by promoting luteolysis via the synthesis and release of uterine PGF-2 alpha.
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PMID:Patterns of oxytocin secretion during the oestrous cycle of the mare. 347 79

Conceptuses produce steroids, prostaglandins, proteins and possibly other unidentified agents which may play a role in the establishment and maintenance of pregnancy. A key event in this process is protection of the corpus luteum (CL) from the luteolytic activity of prostaglandin (PG) F-2 alpha of uterine origin. Oestrogens produced by the pig conceptuses between Days 11 and 16 appear to exert an antiluteolytic effect resulting in the sequestering of PGF-2 alpha within the uterine lumen. Failure of the pregnant uterus to release PGF-2 alpha in an endocrine fashion, therefore, allows for maintenance of CL function. Conceptuses of sheep and cattle produce proteins which, when introduced into the uterine lumen of nonpregnant ewes and cows, suppress the ability of oestradiol and oxytocin to stimulate uterine production of PGF-2 alpha. These conceptus secretory proteins appear to exert an antiluteolytic effect by inhibiting uterine production of luteolytic amounts of PGF-2 alpha. The horse conceptus produces both oestrogens and proteins during early pregnancy when uterine production of PGF-2 alpha is suppressed. Co-culture of horse endometrium and conceptus inhibits endometrial production of PGF-2 alpha. Conceptuses of pigs, sheep and cattle undergo elongation to achieve apposition between trophectoderm and endometrium but the horse embryo migrates rapidly and consistently throughout the uterus to achieve endometrial contact.
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PMID:Role of conceptus secretory products in establishment of pregnancy. 351 18

Active immunization against oxytocin significantly prolonged the oestrous cycle in 3 out of 4 goats; the mean (+/- s.e.m.) cycle length was 29.1 +/- 1.7 days (n = 12) compared to 19.4 +/- 0.6 days (n = 9) in control animals. During Days 10-21 of the cycle in the 3 responsive goats, peripheral plasma concentrations of progesterone and oxytocin were steady and those of 13,14-dihydro-15-keto-prostaglandin F-2 alpha were very low (50-100 pg X ml-1) with no marked pulsatile activity. The major effect of immunization would appear to be suppression of the synthesis of the uterine luteolysin PGF-2 alpha, thus confirming that endogenous oxytocin has a facilitatory role in luteolysis via prostaglandin production.
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PMID:Suppression of prostaglandin F-2 alpha release and delay of luteolysis after active immunization against oxytocin in the goat. 386 68

Corpora lutea from cyclic ewes were dissociated by collagenase and trypsin/EGTA treatments, and enriched fractions of small and large luteal cells were prepared on gradients of Ficoll. These fractions were incubated separately or remixed before incubation. Colchicine, cytochalasin B and the calcium channel-blocker verapamil significantly reduced progesterone production by both small and large luteal cell fractions, while isoprenaline stimulated an increase in progesterone production by large luteal cell fractions only. When fractions of small and large luteal cells were remixed, no more and no less progesterone was produced than would have been predicted from equivalent fractions incubated separately. There was therefore no evidence of synergism between small and large luteal cells in the production of progesterone. Prostaglandin F-2 alpha, which can inhibit LH-stimulated progesterone production by ovine luteal tissue in vitro, had no effect on LH-stimulated progesterone production by small luteal cell fractions, but significantly inhibited that by enriched fractions of large luteal cells. Since large luteal cell fractions were contaminated with small luteal cells, which are probably responsible for the progesterone-secretory response of these fractions to LH, it was concluded that the inhibition of LH-stimulated progesterone production by small luteal cells is dependent on the presence of large luteal cells. Oxytocin added to large and small luteal cell fractions did not affect progesterone production by either fraction. It was therefore concluded that the inhibitory action of PGF-2 alpha on LH-stimulated progesterone production may require the interaction of large and small luteal cells, but that oxytocin is not likely to be an intermediary in this interaction.
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PMID:Do small and large luteal cells of the sheep interact in the production of progesterone? 386 69

This is a review from the literature dealing with the physiology of prostaglandins (PGs). PGs E and F are biosynthesized from straight chain C-20 fatty acids, arachidonic acid being the precursor of 2 of the series and dihomo-linolenic acid the precursor of the other series. Availability of certain cofactors during synthesis probably determines which PG is formed. The amounts of PGs in the tissues are very low, indicating that they are biosynthesized immediately before hormone-stimulated release. PGs seem to be metabolized by all body tissues. PGE and PGF cannot act as circulating hormones since they are 95-99% deactivated by 1 passage of the blood through the lungs. The following roles of PGs in the reproductive process are discussed: 1) present in semen, they may aid in fertilization; 2) they may function as mediators between luteinizing hormone and cyclic AMP during ovulation; 3) they may facilitate release of anterior pituitary hormones; 4) they act to stimulate progesterone secretion; 5) they act in some species as the uterine luteolytic hormone; and 6) they sensitize the uterus to oxytocin during delivery. Since every body tissue appears to be able to synthesize PGs, they also have other physiological functions.
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PMID:The physiology of prostaglandins. 435 87

This letter comments on a previously published article (August 17, p. 428) relating to the use of prostaglandins for midtrimester abortion. It is estimated that prostaglandin PGF-2-alpha given by the i ntrauterine route has been used in over 5000 patients; 13 cases of cervi cal rupture have been reported. Most ruptrues have occurred in primigravidae. All but 1 of them (who received PGE-2) were given PGF-2-alpha intraamniotically. Periods of gestation have been 15-22 weeks. Large doses of prostaglandins have been used and often supplemented by other oxytocics such as urea or oxytocin. No reported cervical ruptures have followed use of PGE-2 alone, possibly because of its relaxant effect on the cervix. Previous gradual dilatation of the cervix with laminaria tents or with some synthetic prostaglandin analogue is being studied. In first trimester pregnancies prostaglandin analogues given as a single extraamniotic dose 12 or more hours prior to termination has been shown to effect gradual dilatation of the cervix. Of 88 such cases, only 3 required mechanical dilatation of the cervix. It is felt that prostaglandins offer an attractive alternative to hysterotomy or hypertonic saline for terminating second trimester pregnancies when overstimulation of the uterus by large doses is avoided.
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PMID:Letter: Mid-trimester termination. 441 98


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