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)

The maternal administration of meclofenamic acid (a prostaglandin synthetase inhibitor) to pregnant sheep prevented the dexamethasone-induced delivery of live lambs and delayed delivery after foetal death in utero. Administration of meclofenamic acid had no effect on the changes in the levels of progesterone and oestrogen in the plasma which occur before lambing in response to foetal glucocorticoid. Despite normal maternal endocrine changes, increased uterine activity did not occur at the expected time, although it could be elicited by vaginal distension or by administration of oxytocin. The rates of cervical ripening and dilatation were reduced by meclofenamic acid and lambing was frequently associated with some degree of cervical dystocia. Withdrawal of meclofenamic acid did not immediately result in an increase in the level of prostaglandin F in the plasma despite the appearance of co-ordinated uterine contractions; the concentration of prostaglandin in the plasma was not raised until vaginal passage of the lambs. It is concluded that the synthesis or release of prostaglandins mediates the effects of changes in the levels of steroids in the maternal plasma on uterine contractility in sheep.
 ...
PMID:Use of meclofenamic acid to investigate the role of prostaglandin biosynthesis during induced parturition in sheep. 56 81

Treatment of pregnant rats with 1 mg indomethacin/kg twice daily i.m. beginning on Day 20 delayed the onset of parturition by about 21 hr and prolonged the duration of spontaneous parturition by 4 hr. Plasma progesterone and oestradiol levels were determined in daily samples of peripheral blood, and uterine contractions were recorded before and during parturition by means of small, chronically implanted intrauterine balloons which were connected to pressure transducers via fluid-filled catheters. Indomethacin treatment did not inhibit or suppress spontaneous or oxytocin-induced contractions, which were of the same intensity in indomethacin-treated as in control rats. Parturition was induced with oxytocin in the same proportion of treated and control rats, but its induction was not successful in treated rats until 1 day later than in control rats, but its induction was not successful in treated rats until 1 day later than in controls. The onset of parturition was always related to the plasma progesterone level, which declined at a slower rate in indomethacin-treated than in control rats, reaching baseline values approximately 1 day later in the treated animals. The appearance of 20alpha-hydroxysteroid dehydrogenase in the CL of pregnant rats normally occurs on Day 21 of gestation, but activity was not observed until about 1 (0-3) day later in the indomethacin-treated rats, indicating that luteolysis was retarded. Prostaglandin F-2alpha infusions given on Day 21 reversed the effects of indomethacin treatment on plasma progesterone, luteal 20alpha-hydroxysteroid dehydrogenase activity and the timing and duration of parturition, and reduced the high perinatal mortality associated with indomethacin treatment, suggesting that the effects of indomethacin were related to its inhibitory action on prostaglandin synthetase activity. It is concluded that, in rats, indomethacin exerts its effects on parturition through inhibition of luteal regression which was significantly retarded but not prevented, and that indomethacin does not have a direct effect on myometrial contractility.
 ...
PMID:The effect of indomethacin on uterine contractility and luteal regression in pregnant rats at term. 103 79

In this study, we examined whether the mechanisms mediating the induction of grooming behavior by oxytocin (OT) is similar to mechanisms mediating the effects of OT on uterine contractility. Sprague-Dawley strain female rats were injected intracerebroventricularly (ICV) with OT or OT analogues and then were observed for grooming behaviors 25 minutes later for 30 minutes. The uterotonic analogue deamino-OT injected ICV at equimolar doses to 1 microgram OT significantly elevated grooming scores although less than did OT. Other agonist analogues were not effective in inducing an increase in grooming behavior. The simultaneous ICV injection of the analogue [Pen1, Phe2, Thr4, delta 3, 4Pro7, Orn8]-OT, which blocked the effects of OT on uterine contractility, also blocked the effect of OT on grooming behavior. Injection of the same dose of this antagonist analogue did not effect the increased grooming behavior after AVP injection. Pretreatment with 5 mg/kg of the prostaglandin synthetase inhibitor indomethacin significantly inhibited OT-induced grooming. We have concluded from these data that the mechanism underlying the effect of OT on grooming is similar to its effects on uterine contractility in some respects. However, observations that the OT antagonist analogue blocked OT- but not AVP-induced grooming may suggest that more than one receptor or mechanism exists by which nonapeptides initiate excessive grooming.
 ...
PMID:Is oxytocin-induced grooming mediated by uterine-like receptors? 302 Apr 70

Experiments were conducted to determine the effects of infusing indomethacin, a prostaglandin synthetase inhibitor, into the uterine lumen on the development and function of the bovine corpus luteum in the presence and absence of concurrently administered oxytocin. Each treatment was given twice daily on d 4, 5 and 6 of the estrous cycle. Treatments (six heifers/group) and resulting estrous cycle lengths were as follows: (1) untreated controls, 20.6 +/- .4 d; (2) .2 M phosphate buffer vehicle infused into the uterine lumen, 21.0 +/- .6 d; (3) 40 mg indomethacin infused into the body of the uterus, 16.5 +/- 1.0 d; (4) 150 USP units oxytocin injected sc, 10.0 +/- 1.2 d and (5) a combination of oxytocin and indomethacin as in treatments 3 and 4, 14.1 +/- 1.3 d. Plasma concentrations of progesterone were lower (P less than .05) in each treatment group from d 7 onward, when compared with untreated and vehicle-treated controls. Indomethacin alone effectively inhibited the development and function of the corpus luteum, and was without effect on oxytocin-induced inhibition of luteal function. In summary, it appears that a prostaglandin of either uterine or ovarian origin, or both, is required for the normal development and function of the bovine corpus luteum.
 ...
PMID:Inhibition of bovine luteal function by indomethacin. 403 10

1. Indomethacin and meclofenamate, both of which are potent inhibitors of prostaglandin synthetase, antagonized the contractor effects of oxytocin on the isolated uterus from the non-pregnant rat. Contractions induced by acetylcholine or prostaglandin F(2a) were not antagonized.2. Uteri from rats 17-22 days pregnant exhibited intermittent spontaneous contractions when used as isolated preparations. They also released prostaglandin-like activity (mainly similar to F(2a)) into the bathing fluid. Both the prostaglandin release and the uterine activity were abolished by indomethacin. Activity could be restored by addition of low concentrations of prostaglandin E(2) or F(2a).3. The release of prostaglandin F(2a)-like activity by the uteri increased dramatically on the expected day of delivery (day 22).4. The results add force to the hypothesis that the spontaneous activity of some isolated organs is due to an intramural prostaglandin generation, and that increased uterine prostaglandin production contributes to the expulsion of the foetus.
 ...
PMID:The contribution of prostaglandin production to contractions of the isolated uterus of the rat. 478 6

Synthetic bovine parathyroid hormone containing the 1-34 NH2 terminal amino acids [bPTH-(1-34)] is capable of inhibiting stimulated uterine contraction. The purpose of the present investigation is to determine whether the inhibitory action of bPTH-(1-34) is a direct action of the hormone fragment. The effect of different synthetic preparations of bPTH-(1-34), salmon calcitonin, corticotropin-inhibiting peptide and bovine serum albumin on oxytocin-stimulated uterine contraction was determined. In addition, the effects of atropine, propranolol, phentolamine, pyrilamine, cimetidine and the prostaglandin synthetase inhibitor indomethacin on the inhibitory action of bPTH-(1-34) on uterine contraction was determined. Both synthetic preparations of bPTH-(1-34) inhibited oxytocin-initiated contractions similarly. Salmon calcitonin, corticotropin-inhibiting peptide, and bovine serum albumin did not alter oxytocin-stimulated uterine contractions. The salmon calcitonin also did not alter the ability of bPTH-(1-34) to exert its inhibitory effect on uterine contraction. Cholinergic, alpha and beta adrenergic, histaminergic (H1 and H2) and prostaglandin synthetase inhibitors did not alter the action of bPTH-(1-34). These results suggest that the action of bPTH-(1-34) is 1) not due to the presence of a contaminant in the synthetic hormone preparation and 2) that the effect could be due to a direct action effect of the hormone fragment on uterine tissue.
 ...
PMID:Direct effect of parathyroid hormone on rat uterine contraction. 608 71

The existing data on the hormonal factors involved in human parturition indicate that the steroid hormones, progesterone and the oestrogens, play only a facilitatory role in the initiation of labour. A definite role for fetal adrenal steroids in this process has yet to be established, and they too may serve only a facilitating function. The stimulation of the uterine muscle during labour results from an interaction of oxytocin and prostaglandin (PG) F2 alpha. Recent evidence suggests that oxytocin is most important for the initial phase of labour, whereas increased synthesis of PGF2 alpha is essential for the progression of labour. The role of PGE2 remains unclear, but this PG may play an important role in the ripening of the cervix which in turn is essential for successful parturition. The finding of maximal oxytocin receptor concentrations in the myometrium in labour adds strong support to the notion that oxytocin is the trigger for uterine contractions. The factors which control oxytocin receptor formation are therefore important; this may be one of the processes where the steroids play a crucial role. Oxytocin is also one of the stimuli that increase uterine PG synthesis; the coupling of oxytocin receptor occupancy and PG synthetase activity in uterine tissues may be another crucial factor in the mechanism of labour. The formation of gap junctions between the myometrial cells also seems essential for the synchronization and progression of myometrial activity. We propose, therefore, that the co-ordinating of oxytocin receptor formation, PG synthesis and gap junction formation is a key to the initiation and maintenance of human labour. The fetus may fulfil such a co-ordinating role through its influence on placental oestrogen production, through mechanical distention of the uterus, and through its secretion of neuro-hypophysial hormones and other stimulators of PG synthesis.
 ...
PMID:Endocrinology of human parturition: a review. 609 29

Luteolysis in the goat was characterised by the pulsatile appearance of both oxytocin and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), the primary pulmonary metabolite of prostaglandin (PG) F2 alpha, in the peripheral circulation. The episodic, surge release of oxytocin was superimposed on declining levels which paralleled the fall in progesterone concentrations. Daily subcutaneous administration of the prostaglandin synthetase inhibitor indomethacin (10 mg kg-1) between days 11 and 16, delayed luteolysis and suppressed both the decline in oxytocin concentrations and the pulsatile appearance of both oxytocin and PGFM in the peripheral circulation. Although there was little evidence of the release of the two hormones being synchronised, the results suggest that PGF2 alpha may stimulate pulsatile oxytocin release at luteolysis.
 ...
PMID:Delayed luteolysis and suppression of the pulsatile release of oxytocin after indomethacin treatment in the goat. 653 94

The effect of oxytocin and indomethacin on luteal function during the estrous cycle in goats was investigated. Daily subcutaneous administration of oxytocin given on days 12-15 of the estrous cycle had no effect on length of the cycle or concentrations of progesterone and estradiol-17 beta. Oxytocin given on days 3-6 shortened the cycle and decreased concentrations of progesterone, but increased the estradiol-17 beta to levels similar to seen at estrus. These changes caused by oxytocin were prevented by indomethacin, a prostaglandin synthetase inhibitor, although indomethacin given alone did not affect luteal function. These results suggest that luteal function affected by prostaglandin in the early luteal phase of goats may be different from that in cattle.
 ...
PMID:Effect of oxytocin and indomethacin on the estrous cycle of goats. 799 78

Merino ewes were given a prostaglandin synthetase inhibitor, Finadyne (50 mg flunixin meglumine ml-1), on days 14-16 of the oestrous cycle (day of oestrus = day 0), Finadyne on days 14-16 plus PGF2 alpha on days 15-16, or progesterone on days 14-17 plus PGF2 alpha on days 15-16. Blood samples were taken once a day on days 10-14 and three times a day on days 15-16 for progesterone measurement. The concentrations of oxytocin receptors were measured in the endometrial (pooled caruncular and intercaruncular) tissues collected on day 17. Treatment of ewes with Finadyne resulted in the maintenance of high plasma concentrations of progesterone and a small, but nonsignificant, reduction in the concentrations of endometrial oxytocin receptors. Co-administration of PGF2 alpha reversed this effect of Finadyne. Treatment with both progesterone and PGF2 alpha increased the concentrations of progesterone in plasma and significantly reduced the concentrations of endometrial oxytocin receptors compared with those in the control ewes. These data indicate that withdrawal of progesterone from the circulation as a result of spontaneous luteolysis or by a PGF2 alpha-induced luteolysis caused an increase in the concentrations of oxytocin receptors. However, maintenance of plasma progesterone concentrations over the period of normal luteolysis only partially inhibited the concentrations of endometrial oxytocin receptors. There results suggest that the increase in the concentrations of oxytocin receptors at luteolysis in the naturally cycling ewes may be due to the loss of the inhibitory effects of progesterone on uterine oxytocin receptors.
 ...
PMID:Role of progesterone in the control of endometrial oxytocin receptors at luteolysis in sheep. 839 29


1 2 Next >>