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

1. The actions of angiotensin II, bradykinin, oxytocin, arginine vasopressin, relaxin, serotonin and the prostaglandins E2 and F2 alpha were examined on preparations of costo-uterine muscle from stilboestrol-treated rats. 2. All the agonists, except relaxin, when used in concentrations which contract the rat uterus, also produced contractions of costo-uterine muscles. Concentration-response curves were steep and maximal responses to the agonists were comparable. The negative log molar EC50 values were: serotonin, 6.5; angiotensin II, 8.8; bradykinin, 8.4; PGE2, 8.3; PGF2 alpha, 7.1. The EC50 values (units/L) for oxytocin and vasopressin were 4.4 and 2.7 respectively. 3. Indomethacin (2.8 or 5 mumol/L) did not decrease the contractile effects of the peptides or serotonin. The effects of serotonin were reduced, but not reversed, by methysergide (0.94 mumol/L). 4. Porcine relaxin inhibited field stimulation-induced contractions of costo-uterine muscle and uterine horns from immature rats pretreated with oestradiol cypionate and from stilboestrol-treated mature rats. It was much less potent, and its effects were less clearly concentration-related, on costo-uterine muscle. 5. The inhibitory effects of relaxin on the uterus were unaffected by propranolol (1 mumol/L), confirming that on this tissue relaxin acts independently of the release of catecholamines. Progesterone (30 mumol/L) was also without effect on the action of relaxin on the uterus. 6. These results taken together indicate that the costo-uterine muscle of the rat: (i) contracts in response to serotonin and the peptides angiotensin II, arginine vasopressin, bradykinin and oxytocin independently of the release of the contractile prostaglandins F2 alpha and E2; and (ii) in contrast to the uterus, may lack a significant population of receptors for relaxin.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Actions of some autacoids and peptides, including relaxin, on costo-uterine muscle from rats. 257 64

Two mares received PGF-2 alpha twice daily until abortion and 2 mares received a combined treatment with oestradiol benzoate and oxytocin. The mares were about 150 days pregnant. The PG-treated animals aborted after 37 and 61 h, respectively, and the fetuses were expelled in intact fetal membranes. The other 2 mares aborted 13 and 27 h after the first oxytocin injection, respectively, and showed strong uterine contractions and expelled the fetuses in disrupted fetal membranes. Concentrations of 15-ketodihydro-PGF-2 alpha increased both after PG and oxytocin injections and in association with the abortion, but after the PG-induced abortion there was an immediate return to basal levels and after the oxytocin-induced abortion there was a large increase in the concentrations, indicating damage of the uterus. Progesterone and relaxin concentrations followed the placental function and decreased in association with the abortions. Oestrone sulphate values differed in the two groups; the oxytocin-treated animals showed a rapid decrease while the mares treated with PG showed first a marked increase and then a decrease. Concentrations of PMSG appeared to be unaffected by the abortions.
 ...
PMID:Hormonal changes associated with induced late abortions in the mare. 282 69

Five new concepts concerning the control of corpus luteum function in the cow have been developed in recent years. Prostacyclin (PGI-2) plays a luteotrophic role. Conversely, products of the lipoxygenase pathway of arachidonic acid metabolism, particularly 5 hydroxyeicosatetraenoic acid (5-HETE), play luteolytic roles. Luteal cells arise from two sources. The small luteal cells are all of theca cell origin; the large cells found early in the cycle (Days 2-6) are mainly of granulosa cell origin. However, a population of large cells found after Day 10 of the cycle are of theca cell origin. Oxytocin of luteal cell origin plays a role in development of the corpus luteum and possibly in its regression. The recently described Ca2+-polyphosphoinositol-protein kinase C second messenger system, as well as the LH-cAMP system, is involved in control of progesterone synthesis in the bovine corpus luteum. Progesterone synthesis in the small theca-derived luteal cells is primarily controlled by the cAMP system. However, elevated intracellular calcium diminishes cAMP-mediated progesterone synthesis in these cells. These findings modify our current concepts of the mechanisms of control of progesterone secretion by the corpus luteum and suggest several new lines of research.
 ...
PMID:Hammond memorial lecture. New concepts of the control of corpus luteum function. 302 24

Twenty ovariectomized ewes were used in an experiment designed to examine the interaction of progesterone, estradiol, and oxytocin in the regulation of uterine secretion of prostaglandin F2 alpha (PGF2 alpha). All ewes underwent a steroid pretreatment that mimicked the changes in progesterone and estradiol which occur during the six days immediately prior to estrus. After pretreatment, ewes were randomly assigned to 1 of 4 treatment groups: 1) control (n = 4); 2) estradiol-17 beta (n = 6); 3) progesterone (n = 4); and 4) progesterone and estradiol-17 beta (n = 6). Progesterone was injected twice daily for 15 days. The dose of progesterone varied with day postestrus in a manner designed to simulate endogenous luteal secretion of progesterone. Estradiol-17 beta was administered in s.c. Silastic implants. The implants maintained circulating concentrations of estradiol at 3 pg/ml. On Days 5, 10, and 15 of treatment, ewes were injected with oxytocin (10 IU in 1.0 ml saline, i.v.). Jugular venous blood samples were collected beginning one-half hour prior to and continuing for 2 hours post-oxytocin injection for quantification of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM). No changes in concentration of PGFM following injection of oxytocin were observed on Day 5 or 10 in any treatment group. Concentrations of PGFM increased following injection of oxytocin on Day 15 only in groups receiving progesterone. Both the area under the PGFM response curve (p = 0.08) and peak response (p = 0.06) were greater in ewes treated with progesterone and estradiol-17 beta than in those receiving progesterone alone.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of progesterone and estradiol-17 beta on uterine secretion of prostaglandin F2 alpha in response to oxytocin in ovariectomized ewes. 316 88

The production of luteal oxytocin in ewes, resulting from the intrajugular injection of 200 micrograms of PGF2 alpha, could be determined by the increase in intramammary pressure. This simple indirect method of measuring the activity of the corpus luteum enabled easy detection of renewed post-partum ovulation or the onset of pregnancy. The response was monitored every two days between Days 0 and 25, then every 4 days between Days 25 and 59 in: 9 cyclic ewes (group B); 9 cyclic ewes treated with three daily intramuscular injections of 25 mg of Trilostane, a steroid synthesis inhibitor, between Days 7 and 25 (group A); 11 pregnant ewes (group C). Progesterone levels were determined each day from blood sampled in the jugular vein. Trilostane produced a decrease in plasma progesterone, not a total suppression (fig. 3), but did not significantly modify the intramammary pressure variations resulting from PGF2 alpha injections. These were identical in both cyclic and pregnant ewes during the first 15 days: they increased from D0 to D7 and decreased between D12 and D15 (fig. 4). After D15, the increase in intramammary pressure progressively weakened and became 0 at D17 in the cyclic ewes, whereas in the pregnant animals there was a renewed increase in intramammary pressure until D20; this regressed progressively afterwards and disappeared towards D45. This transitory, renewed activity between D15 and D20 might be an indirect or direct result of the message delivered by the embryo to maintain the corpus luteum. Several hypotheses are discussed with a view to explaining this phenomenon.
 ...
PMID:PGF2 alpha-induced milk ejection in ewes having cyclic or pregnant corpora lutea. 316 39

A double-blind, placebo-controlled clinical trial of epostane, a progesterone synthesis inhibitor, as an adjunct to early mid-trimester abortion by extraamniotic PGE2 was conducted. 5 primigravidae 13-18 weeks pregnant received 100 mg epostane 3 times daily for 3 days, and 5 women received identical placebos. Then they were given exponentially increased doses of oxytocin from 2 to 64 mu/min. In 1 hour 1.5 mg PGE2 in 6% Tylose gel was injected extraamniotically, followed by oxytocin at 100 mu/min 6 hours later. The average interval between PGE2 and abortion was 490 min in the epostane group, compared to 1432 min in controls. The treated women required 1 injection of narcotic analgesic, compared to 2 or 3 in controls. Uterine activity, recorded transcervically, was significantly greater during the baseline recording (p0.05) and the PGE2 infusion (p0.001) phases in the treated group, but not during oxytocin infusion. Progesterone had fallen 74% after epostane treatment. This priming technique has potential benefits for women in less pain, lower PGE2 doses, shorter abortion interval and hospital stay. Possibly by maximizing dose and timing, a day-case mid-trimester abortion or even a medical induction of mid-trimester abortion may be possible in the future.
 ...
PMID:Progesterone inhibition in mid-trimester termination of pregnancy: physiological and clinical effects. 332 76

Previously, we have demonstrated the presence of substances reacting like arginine vasopressin (AVP) and oxytocin (OXT) in acid extracts of corpora lutea (CL) of pigs by RIA. The present study examined purified extracts of CL by using HPLC. The results of these experiments show that CL of nonpregnant sows contain AVP and OXT. Little is known about possible auto- and paracrine effects of AVP and OXT in the ovary. Therefore, we investigated the influence of AVP and OXT on progesterone, estradiol, and androstenedione secretion in porcine luteal cell cultures from nonpregnant sows. Progesterone and androstenedione secretion increased significantly (P less than 0.05) in the presence of ovine LH (oLH), whereas no change in basal estradiol levels could be observed under the same conditions. When AVP or OXT was added to the culture system a dose-dependent inhibition of basal as well as oLH-stimulated progesterone secretion was measured. Under basal conditions, a dose of 1 pg AVP/ml decreased progesterone secretion significantly (P less than 0.05), but to reach the same effect in the presence of OXT a dose of 100 ng/ml was necessary. In the presence of oLH the addition of as little as 0.01 pg AVP/ml inhibited progesterone secretion significantly (P less than 0.05). On the other hand, 10 ng OXT/ml or higher doses were needed to decrease oLH-stimulated progesterone release. In the presence of specific peptide antagonists the inhibitory effect on progesterone release was abolished. These results suggest that AVP and OXT effects are mediated through specific receptors. OXT and AVP also inhibited androstenedione secretion, but had no effect on estradiol secretion. Calculation of the ED50 data from dose-response curves of both peptides show that AVP is about 10(4)-fold more active than OXT in inhibiting in vitro progesterone and androstenedione secretion. This suggests that AVP as well as OXT may play an important role in the regulation of ovarian function.
 ...
PMID:Inhibitory effect of oxytocin and vasopressin on steroid release by cultured porcine luteal cells. 335 63

Membrane fractions prepared from the uterine endometrium of untreated ovariectomized sheep contained a 41 x 10(3) Mr protein that was [32P]ADP-ribosylated by pertussis toxin in the presence of [32P]NAD. Progestin and progestin plus oestrogen treatment in vivo increased the concentration of this protein 2.7- and 3.6-fold respectively. Endometrial extracts from untreated or progestin-treated sheep also contained proteins of Mr 69 x 10(3) and 120 x 10(3) which were ADP-ribosylated in the absence of pertussis toxin; these proteins were not ADP-ribosylated in sheep receiving oestrogen. Incubation of endometrial slices from progestin plus oestrogen-treated sheep with oxytocin in vitro increased phosphoinositide hydrolysis 11-fold. This effect was not altered by prior incubation with pertussis toxin, although toxin treatment reduced by 64% subsequent labelling of the 41 x 10(3) Mr protein when membrane fractions prepared from pretreated slices were incubated with pertussis toxin and [32P]NAD. Thus the endometrium contains a pertussis toxin-sensitive protein which is induced by steroid treatment, but this protein is not involved in the phosphoinositide response to oxytocin.
 ...
PMID:Pertussis toxin-catalysed ADP-ribosylation of endometrial proteins in sheep. 339 97

The effects of oestradiol, oxytocin, progesterone and hydrocortisone in vitro on prostaglandin (PG) output from guinea-pig endometrium, removed on days 7 and 15 of the oestrous cycle and maintained in tissue culture for 3 days, have been investigated. Oestradiol (3.7 to 3700 nM) and oxytocin (2 to 200 pM) did not stimulate endometrial PGF2 alpha output, thus not confirming the findings of a previous report (Leaver & Seawright, 1982), nor did they stimulate the outputs of PGE2 and 6-keto-PGF1 alpha. In fact, oestradiol (3700 nM) inhibited the outputs of PGF2 alpha, PGE2 and, to a lesser extent, 6-keto-PGF1 alpha. Progesterone (3.2 to 3200 nM) inhibited the outputs of PGF2 alpha and PGE2; hydrocortisone (2.8 to 2800 nM) had no effect on endometrial PG output. These findings indicate that the inhibitory effect of progesterone on endometrial PG synthesis and release in the guinea-pig is not due to progesterone having a glucocorticoid-like action. Furthermore, progesterone had no effect on 6-keto-PGF1 alpha output, suggesting that the mechanisms controlling endometrial PGI2 synthesis (as reflected by measuring 6-keto-PGF1 alpha) are different from those controlling endometrial PGF2 alpha and PGE2 synthesis.
 ...
PMID:Effects of oestradiol, progesterone, hydrocortisone and oxytocin on prostaglandin output from the guinea-pig endometrium maintained in tissue culture. 343 57

Corpora lutea were collected from sheep on Days 6, 10, and 15 of the oestrous cycle and Day 25 of pregnancy and dissociated into single cell suspensions. Purified preparations of large and small luteal cells were prepared by elutriation on all days except Day 6. Basal progesterone production by large cells was 6-8-fold higher than by small cells (36-65 vs 6-9 fg/cell/min). Oxytocin secretion was maximal on Day 6 (1.0 fg/cell/min) and declined thereafter. The number of receptors for LH increased between Day 6 and Day 10 and the two cell types had an equal number of receptors on Days 10 and 15 (19,000-23,000). Large cells on Day 25 of pregnancy had fewer receptors (12,000) than did small cells (26,000). Progesterone secretion by small luteal cells from all days examined was stimulated by LH (0.01-1000 ng/ml) in a dose-dependent manner; maximum sensitivity to LH occurred on Day 10. Despite the presence of receptors for LH on large cells, LH failed to stimulate progesterone production. Basal production of progesterone by large and small cells, and the response of small cells to LH, was not influenced by day examined. Re-combinations of large and small cells from Day 10 synergized to increase progesterone secretion. Prostaglandin E-2 (0.1-1000 ng/ml) did not stimulate progesterone secretion by large or small cells.
 ...
PMID:Progesterone production, LH receptors, and oxytocin secretion by ovine luteal cell types on days 6, 10 and 15 of the oestrous cycle and day 25 of pregnancy. 357 85


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>